TWI777980B - Polyimide film, laminate, and surface material for display - Google Patents

Abstract

A polyimide film comprising a polyimide that contains silicon atoms, wherein a light transmittance measured in accordance with JIS K7361-1 is 85% or more; wherein a tensile modulus of elasticity at 25℃ obtained by measuring a 15 mm × 40 mm specimen at a tensile rate of 10 mm/min and a chuck distance of 20 mm in accordance with JIS K7127, is 1.8 GPa or more; and wherein both one surface and the other surface contain silicon atoms; a silicon atom concentration of one surface and that of the other surface are different; and a silicon atom concentration of a surface with a relatively high silicon atom concentration is 10.0 atom% or less.

Description

Polyimide film, laminate, and surface material for display

Embodiments of the present invention relate to a polyimide film, a laminate, and a surface material for a display.

Thinner plate glass is excellent in hardness, heat resistance, etc., but has the following disadvantages: it is difficult to bend, it is easy to break when dropped, and there are problems in processability, and it is heavier than plastic products. Therefore, in recent years, from the viewpoint of workability and weight reduction, resin products such as resin substrates and resin films have been used to replace glass products, and research has been conducted on resin products that become glass replacement products.

For example, with the rapid progress of electronic devices such as displays such as liquid crystal and organic EL, and touch panels, thinning, weight reduction, and flexibility of the devices are required. Conventionally, in these devices, various electronic components, such as thin transistors and transparent electrodes, are formed on a relatively thin plate glass. By changing the thin plate glass into a resin film, it is possible to realize the durability of the panel itself. Impact enhancement, flexibility, thinning or lightening.

The polyimide resin is generally a resin with high heat resistance obtained by subjecting polyamic acid obtained by the condensation reaction of an aromatic tetracarboxylic anhydride and an aromatic diamine to a dehydration ring-closure reaction. However, since polyimide resins are generally colored in yellow or brown, it is difficult to use them in fields requiring transparency, such as display applications and optical applications. Therefore, the case where the transparency-improved polyimide is applied to a display member has been studied. For example, in Patent Document 1, as a polyimide resin having high heat resistance, high transparency, and low water absorption, a polyimide resin selected from the group consisting of 1,2,4,5-ring is disclosed. At least one acyl group-containing compound selected from the group consisting of hexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic dianhydride and reactive derivatives thereof and represented by a specific formula It is obtained by reacting at least one imine group-forming compound among the compounds having at least one phenylene group and isopropylidene group, and it is described that the polyimide resin is suitable for substrate materials such as flat panel displays and mobile phones.

In Patent Document 2, as a polyimide film used for a substrate of a flexible device, a polyimide film is disclosed which is colorless and transparent, has low residual stress with an inorganic film, and is mechanically A polyimide film with excellent physical and thermal properties, using a specific fluorine-based aromatic diamine and a polysiloxane compound having a siloxane skeleton with 3 to 200 silicon atoms as monomer components The polyimide precursor is imidized. In Patent Document 2, after forming a polyimide film with an inorganic film (SiN film) using the above-mentioned polyimide precursor, no cracks or peeling were observed after repeated bending test 10 times. It was described as (◯), and when cracks were observed, it was described as (Δ).

On the other hand, as a water-repellent polyimide film, Patent Document 3 discloses a polyimide film obtained by coating a polyimide solution containing polyimide siloxane with The film is imidized, or the surface atomic concentration of silicon atoms is set to 1% or more by imidization after forming a coating of a polyimide siloxane solution on a coating of a polyimide solution.

Patent Document 1: Japanese Patent Laid-Open No. 2006-199945

Patent Document 2: International Publication No. 2014/098235

Patent Document 3: Japanese Patent Application Laid-Open No. 10-110032

The inventors considered that a laminate of a polyimide film and various functional layers containing a resin is effective as a resin product that can be used as a substitute for glass, and made efforts to study it. One of the subjects is to improve the performance of the polyimide film to the resin containing layer. Adhesion. According to the study by the inventors, it was found that a polyimide film appropriately containing silicon atoms improves the adhesion to the resin-containing layer, but there are problems such as the following problems. When peeling from the support, it was difficult to peel, and defects such as wrinkles, cracks, and streaks occurred in the film, or the film was broken. Therefore, in the case of the polyimide film, both the peelability from the support during the production process and the adhesiveness when other layers are laminated are required to be taken into consideration.

In addition, even if it is a polyimide film containing silicon atoms, if it is the water-repellent polyimide film described in Patent Document 3, the light transmittance is low, and it is difficult to use it in fields such as display applications and optical applications that require transparency .

Furthermore, the conventional polyimide film containing polysiloxane has the following situations: insufficient elastic modulus, low surface hardness and easy damage, or transmission of impact to the light-emitting panel or circuit, and insufficient function as a protective film.

In view of the above circumstances, a resin film is required which has both the peelability from the support during the production process and the adhesiveness in the case of laminating other layers, and has sufficient transparency as a transparent film, and has sufficient transparency as a protective film. Surface hardness.

The present invention has been made in view of the above-mentioned problems, and its main object is to provide a polyimide film having improved adhesiveness on one side, suppressed defects caused by peeling from a support on the other side, and reduced transparency and surface hardness. decrease is suppressed.

Moreover, the objective of this invention is to provide the laminated body which has the said polyimide film, and the surface material for displays which are the said polyimide film or the said laminated body.

One embodiment of the present invention provides a polyimide film, which contains polyimide containing silicon atoms, the total light transmittance measured according to JIS K7361-1 is more than 85%, and the stretching speed is set according to JIS K7127. The tensile modulus of elasticity at 25°C measured on a 15mm×40mm test piece at 10mm/min and the distance between the chucks is set to 20mm is 1.8GPa or more. Silicon atoms are contained on one side and the other side, but one side is The concentration of silicon atoms is different from the concentration of silicon atoms on the other side, and the concentration of silicon atoms on the side where the concentration of silicon atoms is relatively high is 10.0 atomic % or less.

One embodiment of the present invention provides a polyimide film containing polyimide containing silicon atoms, and containing silicon atoms in a ratio of 0.2 mass % or more and 4.1 mass % or less in the total polyimide, according to JIS The total light transmittance measured by K7361-1 was 85% or more, and the yellowness calculated according to JIS K7373-2006 was 30 or less. The tensile modulus of elasticity at 25°C measured on a 15mm×40mm test piece is above 1.8GPa. Both sides contain silicon atoms, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side. The silicon atom concentration of the surface with relatively high concentration is 10.0 atomic % or less.

One embodiment of the present invention provides a polyimide film containing polyimide having a structure represented by the following general formula (1-1), and the total light transmittance measured according to JIS K7361-1 is 85% Above, the yellowness calculated according to JIS K7373-2006 is 30 or less, and the tensile speed is 10mm/min and the distance between the chucks is 20mm according to JIS K7127. The test piece of 15mm×40mm is measured at 25°C. The tensile modulus of elasticity is above 1.8GPa, and both sides contain silicon atoms, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side. %the following.

(In general formula (1-1), R ^1' represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ^2' represents a divalent group of a diamine residue, R 2.5 mol % or more and 50 mol % or less of the total amount of ^2' are diamine residues having silicon atoms in the main chain, and 50 mol % or more and 97.5 mol % are those which do not have silicon atoms and are aromatic Diamine residue of ring or aliphatic ring; n' represents the number of repeating units).

One embodiment of the present invention provides a polyimide film comprising a polyimide having a structure represented by the following general formula (1), and the total light transmittance measured according to JIS K7361-1 is 85% or more, The yellowness calculated according to JIS K7373-2006 is 30 or less, and the tensile speed at 10mm/min and the distance between the chucks are set to 20mm according to JIS K7127, and the tensile strength at 25°C is measured on a test piece of 15mm×40mm The elastic modulus is 1.8GPa or more, and silicon atoms are contained on one side and the other side, but the silicon atom concentration on one side is different from that on the other side, and the silicon atom concentration on at least one side is 1.0 atomic % or more.

(In general formula (1), R ¹ represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group of a diamine residue, and the total amount of R ² 10 mol% or more and 50 mol% or less are diamine residues with 1 or 2 silicon atoms in the main chain, 50 mol% or more and 90 mol% or less are no silicon atoms and aromatic Diamine residue of ring or aliphatic ring; n represents the number of repeating units).

In one embodiment of the present invention, there is provided a polyimide film, wherein the polyimide contains an aromatic ring and contains a group selected from (i) a fluorine atom, (ii) an aliphatic ring, and (iii) At least one of the group consisting of a structure in which aromatic rings are linked by a sulfonyl group or a fluorine-substituted alkylene group.

In one embodiment of the present invention, there is provided a polyimide film in which R ¹ in the above-mentioned general formula (1-1) in the polyimide having the structure represented by the above-mentioned general formula (1-1) is provided ^' and R in the above-mentioned general formula (1) in the polyimide having the structure represented by the above-mentioned general formula ( ¹ ) are respectively selected from cyclohexanetetracarboxylic dianhydride residues, cyclopentanetetracarboxyl Acid dianhydride residues, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride residues, cyclobutanetetracarboxylic dianhydride residues, pyrometic acid dianhydride residues, 3 ,3',4,4'-biphenyltetracarboxylic dianhydride residue, 2,2',3,3'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylene base) diphthalic anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene)diphthalic acid At least one tetravalent group selected from the group consisting of a formic anhydride residue, a 4,4'-oxydiphthalic anhydride residue, and a 3,4'-oxydiphthalic anhydride residue.

In one embodiment of the present invention, there is provided a polyimide film, wherein R ² in the above general formula (1-1) in the polyimide having the structure represented by the above general formula (1-1) In the above-mentioned diamine residue having an aromatic ring or an aliphatic ring in ^' , and in the polyimide having the structure represented by the above-mentioned general formula (1), the above-mentioned in R ² in the above-mentioned general formula (1) has The diamine residue of aromatic ring or aliphatic ring is selected from the group consisting of trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4' - diaminodiphenyl residues, 3,4'-diaminodiphenyl residues, 2,2-bis(4-aminophenyl)propane residues, 2,2-bis(4 -Aminophenyl) hexafluoropropane residue, and at least one kind of divalent group in the group consisting of a divalent group represented by the following general formula (2).

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or a perfluoroalkyl group).

In one embodiment of the present invention, a polyimide film is provided, which uses a surface with a relatively large concentration of silicon atoms as a close contact surface with a resin-containing layer containing a radically polymerizable compound and a cationic polymerized layer. A polymer of at least one of the sexual compounds.

An embodiment of the present invention provides a laminate in which the polyimide film of the above-described embodiment of the present invention and a resin-containing layer containing a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound are located in adjacent location.

In one embodiment of the present invention, there is provided a layered product in which the radically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule, and the cationically polymerizable compound is A compound having at least one of two or more epoxy groups and an oxetanyl group in a molecule.

An embodiment of the present invention provides a surface material for a display, which is the polyimide film of the above-described embodiment of the present invention or the laminate of the above-described embodiment of the present invention.

An embodiment of the present invention provides a surface material for a flexible display, which is the polyimide film of the above-described embodiment of the present invention or the laminate of the above-described embodiment of the present invention.

According to the embodiment of the present invention, there can be provided a polyimide film in which the adhesiveness of one side is improved, the defect caused by peeling from the support on the other side is suppressed, and the decrease in transparency and the decrease in surface hardness are suppressed. .

Moreover, embodiment of this invention can provide the laminated body which has the said polyimide film, and the surface material for displays which are the said polyimide film or the said laminated body.

Fig. 1 is a diagram for explaining the method of the static bending test.

1. Polyimide film

The first embodiment of the polyimide film of the present invention is a polyimide film containing polyimide containing silicon atoms, and the total light transmittance measured according to JIS K7361-1 is 85% or more, according to According to JIS K7127, the tensile modulus of elasticity at 25°C is 1.8GPa or more when the tensile speed is set to 10mm/min and the distance between the chucks is set to 20mm. It contains silicon atoms, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side.

The second embodiment of the polyimide film of the present invention is a polyimide film containing a silicon atom-containing polyimide in an amount of 0.2 mass % or more and 4.1 mass % or less in the total polyimide. The ratio contains silicon atoms, the total light transmittance measured according to JIS K7361-1 is 85% or more, the yellowness calculated according to JIS K7373-2006 is 30 or less, the tensile speed is set to 10mm/min according to JIS K7127, the chuck The distance is set to 20mm, and the tensile modulus of elasticity at 25°C measured on a 15mm×40mm test piece is more than 1.8GPa. One side and the other side contain silicon atoms, but the concentration of silicon atoms on one side is different from that on the other side. The atomic concentration is different, and the silicon atomic concentration of the surface with relatively high silicon atomic concentration is 10.0 atomic % or less.

In the above-mentioned second embodiment, in the above-mentioned first embodiment, silicon atoms are contained in a ratio of 0.2 mass % or more and 4.1 mass % or less in the total polyimide, and it is easy to improve the adhesion of one surface of the polyimide film. , and the form of peelability on the other side.

The third embodiment of the polyimide film of the present invention is a polyimide film containing a polyimide having a structure represented by the following general formula (1-1), measured in accordance with JIS K7361-1 The total light transmittance is 85% or more, the yellowness calculated according to JIS K7373-2006 is 30 or less, and the tensile speed is 10mm/min and the distance between the chucks is 20mm according to JIS K7127. The tensile modulus of elasticity measured at 25°C is above 1.8GPa, and both sides contain silicon atoms, but the silicon atom concentration on one side is different from the silicon atom concentration on the other side, and the silicon atom concentration is relatively large. The concentration of silicon atoms is 10.0 atomic % or less.

(In general formula (1-1), R ^1' represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ^2' represents a divalent group of a diamine residue, R 2.5 mol % or more and 50 mol % or less of the total amount of ^2' are diamine residues having silicon atoms in the main chain, and 50 mol % or more and 97.5 mol % are those which do not have silicon atoms and are aromatic Diamine residue of ring or aliphatic ring; n' represents the number of repeating units).

The above-mentioned third embodiment uses the polyimide having the structure represented by the above general formula (1-1) as the silicon atom-containing polyimide in the above-mentioned first embodiment, and it is easy to improve the polyimide film. The form of adhesion on one side and peelability on the other side.

The fourth embodiment of the polyimide film of the present invention is a polyimide film containing a polyimide having a structure represented by the following general formula (1), and the total light measured in accordance with JIS K7361-1 The transmittance is 85% or more, and the yellowness calculated according to JIS K7373-2006 is 30 or less. According to JIS K7127, the tensile speed is set to 10mm/min, and the distance between the chucks is set to 20mm, and the test piece of 15mm×40mm is measured. The tensile modulus of elasticity at 25°C is above 1.8GPa, and silicon atoms are contained on one side and the other side, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side, and the concentration of silicon atoms on at least one side is 1.0 atomic% above.

(In general formula (1), R ¹ represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group of a diamine residue, and the total amount of R ² 10 mol% or more and 50 mol% or less are diamine residues with 1 or 2 silicon atoms in the main chain, 50 mol% or more and 90 mol% or less are no silicon atoms and aromatic Diamine residue of ring or aliphatic ring; n represents the number of repeating units).

In the above-mentioned fourth embodiment, in the above-mentioned first embodiment, a polyimide having a structure represented by the above-mentioned general formula (1) is used as the polyimide containing silicon atoms, and the concentration of silicon atoms on at least one side is 1.0 atomic % or more. The polyimide film is a form that can easily improve the adhesion of one side of the polyimide film and the peelability of the other side. In the above-mentioned fourth embodiment, by using the polyimide having the structure represented by the above-mentioned general formula (1), the silicon atom concentration of the surface having a relatively large silicon atom concentration can be set to 10.0 atomic % or less.

The total light transmittance of the polyimide film of the present invention measured in accordance with the above-mentioned JIS K7361-1 is 85% or more. In this way, since the transmittance is high, the transparency is good, and it can be used as a substitute for glass. The total light transmittance of the polyimide film of the present invention measured in accordance with the above-mentioned JIS K7361-1 is further preferably 88% or more, more preferably 89% or more, and still more preferably 90% or more.

The polyimide film of the present invention preferably has a total light transmittance of 85% or more, more preferably 88% or more, and more preferably 89% or more when the thickness is 5 μm or more and 100 μm or less measured in accordance with the above-mentioned JIS K7361-1. , preferably more than 90%.

In addition, when the polyimide film of the present invention has a thickness of 50 μm±5 μm, the total light transmittance measured according to the above-mentioned JIS K7361-1 is 85% or more, more preferably 88% or more, more preferably 89% or more, More preferably, it is 90% or more.

The total light transmittance measured according to JIS K7361-1 can be measured by, for example, a haze meter (for example, HM150 manufactured by Murakami Color Technology Laboratory). Furthermore, according to the measured value of the total light transmittance of a certain thickness, the total light transmittance of different thicknesses can be calculated by the Lambert-Beer law, and the converted value can be used.

Moreover, it is preferable that the yellowness (YI value) of the polyimide film of this invention calculated based on the said JIS K7373-2006 is 30 or less. In this way, since the yellowness is low, the coloring of the yellow tint is suppressed, the light transmittance is improved, and it can be used as a glass substitute material. Among the yellowness (YI value) calculated based on the above-mentioned JIS K7373-2006, 20 or less is preferable, 15 or less is more preferable, and 10 or less is more preferable.

When the thickness of the polyimide film of the present invention is 5 μm or more and 100 μm or less, the yellowness (YI value) calculated according to the above-mentioned JIS K7373-2006 is preferably 30 or less, more preferably 20 or less, more preferably 15 or less, especially Preferably it is 10 or less.

Further, when the polyimide film of the present invention has a thickness of 50 μm±5 μm, the yellowness (YI value) calculated according to the above-mentioned JIS K7373-2006 is preferably 10 or less, more preferably 7 or less, and more preferably 5 or less.

Furthermore, the yellowness (YI value) can be calculated based on the transmittance, which is based on the above-mentioned JIS K7373-2006, using an ultraviolet-visible-near-infrared spectrophotometer (for example, V-7100 of Nippon Shoko Co., Ltd.) by JIS Measured by the spectrophotometric method specified in Z8722.

Furthermore, the yellowness of different thicknesses can be calculated and used based on the measured value of the yellowness of a certain thickness and the conversion value of each transmittance at each wavelength of different thicknesses, and the conversion value is for a sample of a specific film thickness. The transmittance at each wavelength between 380 nm or more and 780 nm or less measured at intervals of 5 nm is obtained by the Lambert-Beer law in the same manner as the above-mentioned total light transmittance.

Moreover, regarding the polyimide film of the present invention, the tensile elasticity at 25° C. was measured on a test piece of 15 mm×40 mm in accordance with JIS K7127 with a tensile speed of 10 mm/min and a distance between chucks of 20 mm. The modulus is 1.8GPa or more. In this way, since the tensile modulus of elasticity at 25°C (room temperature) is high, the surface hardness enough to be used as a protective film can be maintained at room temperature, and it can be used as a surface material. Among the above-mentioned tensile elastic modulus, 2.0 GPa or more is preferable, and 2.4 GPa or more is more preferable. On the other hand, from the viewpoint of improving the bending resistance, the tensile modulus of elasticity is preferably 5.2 GPa or less. In terms of improving the bending resistance, the tensile modulus of elasticity may be 4.0 GPa or less, or 3.5 GPa or less.

The above tensile modulus of elasticity can be measured by using a tensile testing machine (such as Shimadzu: Autograph AG-X 1N, load cell: SBL-1KN) to cut a test piece of width 15mm x length 40mm from the polyimide film, and then The measurement was performed at 25° C. with a tensile speed of 10 mm/min and a distance between chucks of 20 mm. The thickness of the polyimide film when the above tensile modulus of elasticity is determined is preferably 50 μm±5 μm.

In addition, the polyimide films of the first, second and third embodiments of the present invention contain silicon atoms on one side and the other side, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side, and the concentration of silicon atoms is relatively The silicon atom concentration of the larger surface is 10.0 atomic % or less.

In addition, the polyimide film of the fourth embodiment of the present invention contains silicon atoms on one side and the other side, but the silicon atom concentration on one side is different from the silicon atom concentration on the other side, and the silicon atom concentration on at least one side is 1.0 atom. %above.

Furthermore, in the present invention, the value of atomic % of each atom is the value rounded to the first decimal place in the measurement value according to the rule B of JIS Z8401:1999. For example, the silicon atomic concentration of 1.0 atomic % or more means that the silicon atomic concentration is included as long as the silicon atomic concentration is 0.950 atomic % or more.

The silicon atom concentration of at least one side of the polyimide film of the present invention is 1.0 atomic % or more, and the silicon atom concentration of the side with a relatively large silicon atom concentration is 10.0 atomic % or less. In this case, the adhesion, peelability, and It is preferable in terms of surface hardness.

The absolute value of the difference between the concentration of silicon atoms on one side and the concentration of silicon atoms on the other side is preferably 0.1 atomic % or more, more preferably 0.4 atomic %, in terms of improving the adhesion on one side and the peelability on the other side, respectively. % or more, more preferably 0.8 atomic % or more.

In addition, the silicon atom concentration on the surface where the silicon atom concentration is relatively high is preferably 1.2 atomic % or more, more preferably 1.6 atomic % or more, more preferably 2.0 atomic % or more, in terms of adhesion. In terms of adhesion and surface hardness, it is preferably 8.0 atomic % or less, and more preferably 5.0 atomic % or less.

The silicon atom concentration on the surface where the silicon atom concentration is relatively small is preferably 4.0 atomic % or less, more preferably 2.0 atomic % or less, more preferably 1.5 atomic % or less, in terms of releasability, in terms of bending resistance On the other hand, it is preferably 0.1 atomic % or more, more preferably 0.2 atomic % or more, more preferably 0.5 atomic % or more.

In addition, the silicon atom concentration on the surface where the silicon atom concentration is relatively high is 1.6 atomic % or more and 10.0 atomic % or less, and the absolute value of the difference between the silicon atom concentration on one side and the silicon atom concentration on the other surface is 0.8 atomic % or more. In this case, it is preferable in that both adhesiveness and releasability are taken into consideration, and in particular, the adhesiveness of the surface having a relatively large silicon atom concentration is excellent.

When the silicon atom concentration on the side with the relatively small silicon atom concentration is 1.5 atomic % or less, and the absolute value of the difference between the silicon atom concentration on one side and the silicon atom concentration on the other side is 0.8 atomic % or more, both adhesion is achieved. And peelability, especially the aspect which is excellent in peelability of the surface with a relatively small silicon atom density|concentration is preferable.

In addition, when the silicon atom concentration of the surface with a relatively large silicon atom concentration is 1.6 atomic % or more and 10.0 atomic % or less, and the silicon atom concentration of the surface with a relatively small silicon atom concentration is 1.5 atomic % or less, the increase is increased. Both adhesiveness and peelability are preferable.

Furthermore, in the present invention, each atomic concentration on the surface of the polyimide film can be determined by X-ray photoelectron spectroscopy (XPS) using an X-ray photoelectron spectroscopy device (eg, Theta Probe of Thermo Scientific Corporation) under the following conditions The value of atomic % of each atom measured was obtained.

˙ Incident X-ray: monochromatic Al Kα ray (monochromatic X-ray, hν=1486.6eV)

˙X-ray irradiation area (measurement area): 400μm

˙X-ray output: 100W (15kV˙6.7mA)

˙Photoelectron swept-in angle: 53° (wherein, the sample normal is set to 0°)

˙Static neutralization conditions: electron neutralization gun (+6V, 0.05mA), low acceleration Ar ⁺ ion irradiation

˙Measurement peaks: Si2p, Cls, Nls, Ols, Fls

˙Quantitative: The background value is obtained by Shirley method, and the atomic ratio is calculated by the relative sensitivity coefficient method from the obtained peak area.

According to the present invention, the polyimide contained in the polyimide film contains silicon atoms, has the above-mentioned specific total light transmittance, and the above-mentioned specific tensile elastic modulus, and contains silicon atoms on one side and the other side, but The concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side. The concentration of silicon atoms on the side where the silicon atom concentration is relatively high is less than 10.0 atomic %. By making such a polyimide film, the following polyimide film can be provided. In the film, the adhesiveness of one side is improved, and the defect caused by peeling from the support of the other side is suppressed, and the decrease of transparency and the decrease of surface hardness are suppressed.

The reason for this is presumed as follows.

The inventors of the present invention have focused on polyimide as a resin used as a glass replacement product. Polyimide is known to be excellent in heat resistance due to its chemical structure. Moreover, the present inventors discovered that the adhesiveness of resin containing layers, such as a polyimide film and a hard-coat layer, improves by introducing a silicon atom into polyimide. The reason for this is presumed that by introducing silicon atoms into the polyimide, when the resin-containing laminate layer is formed, the mixing of the polyimide film and the resin-containing layer is moderately excellent.

On the other hand, it was confirmed that the polyimide film in which silicon atoms were introduced into polyimide was difficult to peel off from the support during the production process, and defects such as wrinkles, cracks, and streaks occurred, or the film was broken. situation. However, as described above, it is considered that the adhesiveness and peelability of the resin film are opposite characteristics, and it is difficult to achieve both the adhesiveness and the peelability in the simple substance of the polyimide film which does not have a multilayer structure.

On the other hand, the present inventors found that when a polyimide containing silicon atoms is used, there is a situation in which the silicon atoms in the polyimide film are easily distributed unevenly, and the produced polyimide film has The concentration of silicon atoms on the surface is different from each other on the front and back sides. Furthermore, it was found that in such polyimide films in which the concentration of silicon atoms in the front and back sides were different from each other, the silicon atom concentration of the surface with a relatively large silicon atom concentration was 10.0 atomic % or less, and the tensile elastic mode at room temperature was The polyimide film with a total light transmittance of 1.8 GPa or more and a total light transmittance of 85% or more can take into account both the adhesion and the peelability from the support during the production process, and maintain the surface hardness sufficient as a protective film. Transparency of transparent resin film. The polyimide film of the present invention has a relatively high silicon atom concentration on the side, and the adhesiveness with the resin-containing layer such as a hard coat layer is improved, and on the relatively low silicon atom concentration side, when peeled off from the support during the manufacturing process The peelability is improved. The reason why the concentration of silicon atoms on the front and back sides of the polyimide film of the present invention is assumed to be different from each other is that the molecular chains are arranged so that the amounts of silicon atoms exposed on the front and back sides are different. Although the reason why the molecular chain of the polyimide resin is configured in this way is not clear, it is considered that the polyimide resin contains silicon atoms, and the polyimide film is manufactured by appropriately adjusting the pre-stripping before peeling off the support. In the drying step, the molecular chains are arranged in such a way that silicon atoms are exposed on the surface compared to the surface in contact with the air and the surface in contact with the support. Moreover, it is presumed that the silicon atoms are more likely to be exposed on the surface in contact with the air by drying by increasing the temperature stepwise in the drying step before peeling off the support. Specifically, first, drying is performed at a low temperature of less than 70°C. At this stage, since the solvent is sufficiently present in the film, the silicon atoms in the coating film are presumably present in the film almost equally. It is presumed that if it is heated at a temperature of 70° C. or higher and then dried, the site containing silicon atoms tends to aggregate on the film surface. Moreover, as in Comparative Example 2 below, when the concentration of silicon atoms on the surface of the polyimide film is too large, the adhesiveness with the resin-containing layer becomes insufficient. The reason for the decrease in adhesion is presumed to be that the surface of the polyimide film was excessively dissolved due to the solvent in the resin-containing layer-forming composition used for forming the resin-containing layer, and when the resin-containing layer-forming composition was hardened , the dissolved part of the surface of the polyimide film is hardened again. During this process, the interface between the polyimide film and the resin-containing layer is fragile due to aggregation of wrinkles or cracks. On the other hand, it is considered that the polyimide film according to the first, second and third embodiments of the present invention has a silicon atom concentration of 10.0 atomic % or less on the surface where the silicon atom concentration is relatively high, so that such adhesion can be improved. decrease is suppressed.

In addition, the polyimide film of the present invention is excellent in releasability from the support during the production process, so in the case of thermal imidization, it can be peeled off from the support in the state of the coating film before imidization. Therefore, when the polyimide film of the present invention is produced, the stretching treatment can be performed in the state of the coating film before imidization, whereby the shrinkage of the produced polyimide film can be suppressed and the elastic modulus can be improved. In addition, in the case of peeling the support after thermal imidization on the support, the following problems occur: during thermal imidization, the polyimide film shrinks on the support, so the The part lifts up from the support to cause curling or cracking. On the other hand, in the present invention, since the coating film can be peeled off from the support in the state before imidization, it is possible to produce a highly elastic polyimide film in which the occurrence of curling and cracking is suppressed.

In addition, if the strength of the coating film before imidization is insufficient, the following defects are likely to occur: when peeling from the support, the coating film is stretched due to the peeling stress, resulting in streaks, or the stretched coating film is not imidized. folds after shrinking. The concentration of silicon atoms on the casting surface of the polyimide film of the present invention is relatively low, and the pre-imidation coating film used to form the polyimide film with a tensile elastic modulus of 1.8 GPa or more has sufficient strength, so streaks or wrinkles can be suppressed.

On the other hand, in the case where imidization is performed by chemical imidization without thermal imidization, high-temperature heat treatment as in thermal imidization can be avoided, so that thermal effects can be suppressed. caused the shrinkage of the membrane. However, even in the case of chemical imidization, if the strength of the polyimide resin coating film peeled from the support itself is insufficient, it is easy to cause the coating film to stretch due to peeling stress when peeled from the support. Defective peeling such as streaks occurs. The concentration of silicon atoms on the casting surface of the polyimide film of the present invention is relatively low, and the polyimide resin coating film used to form the polyimide film having a tensile modulus of elasticity of 1.8 GPa or more has sufficient strength, so that peeling defects can be suppressed.

In addition, as in Comparative Examples 1 and 2 below, it was confirmed that when the tensile modulus of elasticity of the film is small, the surface hardness becomes insufficient. In contrast, the polyimide film of the present invention has a tensile modulus of elasticity at room temperature of 1.8 GPa or more, thereby suppressing the decrease in surface hardness at room temperature and maintaining sufficient performance even at room temperature. The surface hardness of the protective film. Therefore, the polyimide film of the present invention is excellent in scratch resistance to prevent surface damage, and also excellent in impact resistance to prevent breakage of the member located below it.

Moreover, since the polyimide film of this invention can be set as a single-layer structure, it becomes easy to improve transparency. The polyimide film of the present invention can achieve the above-mentioned problems with a single-layer structure, and therefore has high productivity.

Hereinafter, the polyimide film of the present invention will be described in detail.

The polyimide film of the present invention contains polyimide containing silicon atoms, and has the above-mentioned specific characteristics. In the range which does not impair the effect of this invention, other components may be further contained, and another structure may be sufficient.

1. Polyimide

The polyimide is obtained by reacting a tetracarboxylic acid component and a diamine component. It is preferable to obtain a polyamic acid by the polymerization of a tetracarboxylic acid component and a diamine component, and to carry out imidization. The imidization can be performed by thermal imidization or chemical imidization. In addition, it can also be produced by using the method of thermal imidization and chemical imidization in combination.

The polyimide used in the polyimide film of the present invention contains polyimide containing silicon atoms.

The content ratio (mass %) of silicon atoms in the total polyimide contained in the polyimide film of the present invention is not particularly limited. Atom % or less and the silicon atom concentrations in the front and back of the polyimide film are made different from each other, the adhesion and peelability of the polyimide film are taken into consideration, and the bending resistance and surface hardness are taken into consideration. Preferably it is 0.2 mass % or more and 4.1 mass % or less, More preferably, it is 0.5 mass % or more and 4.1 mass % or less.

Here, the content ratio (mass %) of the silicon atom in the total polyimide contained in the polyimide film can be calculated|required from the molecular weight added at the time of manufacture of polyimide. In addition, the content ratio (mass %) of silicon atoms in the total polyimide contained in the polyimide film can be determined by using high performance liquid chromatography, gas chromatography mass spectrometer for the decomposition product of polyimide. , NMR, elemental analysis, XPS/ESCA and TOF-SIMS.

In addition, the polyimide used in the present invention may contain one kind or two or more kinds.

As a polyimide containing a silicon atom, the polyimide containing any one of a tetracarboxylic-acid residue which has a silicon atom, and a diamine residue which has a silicon atom is mentioned, for example. Among them, it is easier to make the concentration of silicon atoms different from each other on the front and back of the polyimide film, the adhesiveness and peelability of the polyimide film are taken into consideration, and the bending resistance and surface hardness are taken into consideration. The polyimide containing the diamine residue which has a silicon atom is preferable, and the polyimide which contains the diamine residue which has a silicon atom in a main chain is more preferable.

Here, the tetracarboxylic acid residue refers to a residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and represents the same structure as a residue obtained by removing an acid dianhydride structure from a tetracarboxylic dianhydride. In addition, the diamine residue refers to a residue obtained by removing two amine groups from diamine.

In the polyimide containing diamine residues having silicon atoms, it is easy to compare the concentration of silicon atoms with respect to the ratio of diamine residues having silicon atoms in 100 mol% of the total amount of diamine residues. The silicon atom concentration of the large surface is 10.0 atomic % or less, and the silicon atom concentration is different on the front and back sides of the polyimide film, and the adhesion and peelability of the polyimide film are taken into consideration. In terms of resistance and surface hardness, it is preferably 2.5 mol % or more and 50 mol % or less.

As the polyimide containing a silicon atom, among them, a polyimide having a structure represented by the following general formula (1-1) is preferable.

(In general formula (1-1), R ^1' represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ^2' represents a divalent group of a diamine residue, R 2.5 mol % or more and 50 mol % or less of the total amount of ^2' are diamine residues having silicon atoms in the main chain, and 50 mol % or more and 97.5 mol % are those which do not have silicon atoms and are aromatic Diamine residue of ring or aliphatic ring; n' represents the number of repeating units)

It is considered that the polyimide having the structure represented by the above general formula (1-1) has a soft molecule having a silicon atom in the main chain of a specific amount introduced between the molecular skeletons containing an aromatic ring or an aliphatic ring. Due to the specific structure of the skeleton, it is easy to arrange molecular chains in a way that silicon atoms are exposed on the surface. Since the silicon atoms in the polyimide film are more likely to be unevenly distributed, the adhesion and peeling of the polyimide film can be further considered. sex. Furthermore, the polyimide having the structure represented by the above-mentioned general formula (1-1) has a high tensile elastic modulus and is excellent in surface hardness by having a molecular skeleton containing an aromatic ring or an aliphatic ring.

The tetracarboxylic acid residue in R ^1' of the general formula (1-1) can be a residue obtained by removing an acid dianhydride structure from a tetracarboxylic dianhydride having an aromatic ring, or a residue having an aliphatic ring The residue obtained by removing the acid dianhydride structure from the tetracarboxylic dianhydride.

As the tetracarboxylic dianhydride having an aromatic ring, for example, pyromic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3, 3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2 ,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether bis Anhydride, bis(3,4-dicarboxyphenyl) stilbene dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methanedi Anhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride , 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis[(3,4-dicarboxy)benzene Formyl]phthalic anhydride, 1,4-bis[(3,4-dicarboxy)benzyl]phthalic anhydride, 2,2-bis{4-[4-(1,2-dicarboxy) Phenoxy]phenyl}propane dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}propanedianhydride, bis{4-[4-(1 ,2-Dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, 4,4'-bis[ 4-(1,2-Dicarboxy)phenoxy]biphthalic anhydride, 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphthalic anhydride, bis{4-[ 4-(1,2-Dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4 -[4-(1,2-Dicarboxy)phenoxy]phenyl}stilbene dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}stilbene dianhydride, bis {4-[4-(1,2-Dicarboxy)phenoxy]phenyl}thioether dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}thioether Dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride Fluoroisopropylidene) diphthalic anhydride, 4,4'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 2,3,6,7-naphthalenetetracarboxylate Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3 , 4,9,10-perylene tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, etc.

Examples of tetracarboxylic dianhydrides having an aliphatic ring include cyclohexane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, and bicyclohexane-3,4,3',4'-tetra Carboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, etc.

These can be used individually or in mixture of 2 or more types.

The diamine residue having a silicon atom in the main chain in R ^2' of the above general formula (1-1) can be a residue obtained by removing two amine groups from the diamine having a silicon atom in the main chain.

As a diamine residue which has a silicon atom in a main chain, the diamine represented by following general formula (A) is mentioned, for example.

(In the general formula (A), L each independently represents a direct bond or -O- bond, and R ¹⁰ each independently represents one of 1 or more and 20 or less carbon atoms which may have a substituent and may contain an oxygen atom or a nitrogen atom. valent hydrocarbon group; R ¹¹ each independently represents a divalent hydrocarbon group with a carbon number of 1 or more and 20 or less, which may have a substituent and may contain an oxygen atom or a nitrogen atom; k is a number of 0 or more and 200 or less; a plurality of L, R ¹⁰ and R ¹¹ may be the same or different respectively)

Examples of the monovalent hydrocarbon group represented by R ¹⁰ include an alkyl group having 1 to 20 carbon atoms, an aryl group, and a combination thereof. The alkyl group may be any of linear, branched and cyclic, and may also be linear or a combination of branched and cyclic.

The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and specific examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isopropyl Butyl, tertiary butyl, pentyl, hexyl, etc. As the cyclic alkyl group, a cycloalkyl group having 3 or more and 10 or less carbon atoms is preferred, and specific examples thereof include a cyclopentyl group, a cyclohexyl group, and the like. The aryl group is preferably an aryl group having 6 or more carbon atoms and 12 or less carbon atoms, and specific examples thereof include a phenyl group, a tolyl group, a naphthyl group, and the like. Moreover, as a monovalent hydrocarbon group represented by R10, an aralkyl group may be ^sufficient , for example, a benzyl group, a phenylethyl group, a phenylpropyl group, etc. are mentioned.

Examples of the hydrocarbon group which may contain an oxygen atom or a nitrogen atom include, for example, a divalent hydrocarbon group below which is bonded to at least one of an ether bond, a carbonyl bond, an ester bond, an amide bond, and an imino bond (-NH-). The above-mentioned monovalent hydrocarbon groups are bonded together.

The substituent which the monovalent hydrocarbon group represented by R ¹⁰ may have is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include halogen atoms such as a fluorine atom and a chlorine atom, and a hydroxyl group.

The monovalent hydrocarbon group represented by R ¹⁰ is preferably an alkyl group having 1 or more and 3 or less carbon atoms, or an aryl group having 6 or more and 10 or less carbon atoms, in terms of both improvement in bending resistance and surface hardness. As the alkyl group having 1 or more and 3 or less carbon atoms, a methyl group is more preferred, and as the aryl group having 6 or more and 10 or less carbon atoms, a phenyl group is more preferred.

Examples of the divalent hydrocarbon group represented by R ¹¹ include an alkylene group having 1 to 20 carbon atoms, an aryl group, and a combination of these groups. The alkylene group may be any of linear, branched and cyclic, and may also be linear or a combination of branched and cyclic.

The alkylene group having 1 to 20 carbon atoms is preferably an alkylene group having 1 to 10 carbon atoms, for example, methylene group, ethylidene group, various propylidene groups, various butylene groups, A combination of a linear or branched alkylene group such as a cyclohexyl group and a cyclic alkylene group, etc.

The above-mentioned aryl-extended group is preferably an aryl-extended group having 6 to 12 carbon atoms, and the aryl-extended group includes a phenyl-extended group, a biphenyl-extended group, a naphthyl-extended group, and the like, and may further have the following para-aromatic ring the substituent.

As a divalent hydrocarbon group which may contain an oxygen atom or a nitrogen atom, at least one of ether bond, carbonyl bond, ester bond, amide bond, and imino bond (-NH-) can be exemplified by combining the above-mentioned divalent hydrocarbon groups with each other. The basis for bonding.

The substituent which the divalent hydrocarbon group represented by R ¹¹ may have may be the same as the substituent which the monovalent hydrocarbon group represented by R ¹⁰ may have.

The divalent hydrocarbon group represented by R ¹¹ is preferably an alkylene group having 1 or more and 6 or less carbon atoms, or an alkylene group having 6 or more and 10 or less carbon atoms, in terms of both improvement in bending resistance and surface hardness. The group is further preferably an alkylene group having 2 or more and 4 or less carbon atoms.

In the above general formula (A), k is a number of 0 or more and 200 or less, among them, preferably 0 or more and 20 or less, and more preferably 0 or 1. That is, among the diamine residues having a silicon atom in the main chain in R ^2' of the above general formula (1-1), a diamine residue having one or two silicon atoms in the main chain is preferable. Examples of the diamine residue having one or two silicon atoms in the main chain include the same diamine residues having one or two silicon atoms in the main chain in R ² of the following general formula (1) By.

The molecular weight of the diamine residue having a silicon atom in the main chain is preferably 3,000 or less, more preferably 2,000 or less, more preferably 1,000, in terms of suppressing the mobility of molecules and imparting bending resistance, and also in terms of surface hardness. Hereinafter, it is more preferably 800 or less, more preferably 500 or less, and still more preferably 300 or less.

The diamine residue having a silicon atom in the main chain may be used alone or in combination of two or more.

The diamine residue that does not have a silicon atom and has an aromatic ring in R ^2' of the above general formula (1-1) can be set to remove 2 amine groups from the diamine that does not have a silicon atom and has an aromatic ring the resulting residue.

As a diamine having no silicon atom and having an aromatic ring, for example, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, and 3,3'-diaminodiphenyl can also be used. base ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diamine diphenyl sulfide, 4,4'-diamino diphenyl sulfide, 3,3,-diamino diphenyl sulfide, 3,4'-diamino diphenyl sulfide, 4,4 '-Diaminodiphenyl benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4 ,4'-diaminobenzylaniline, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2, 2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2-(3-aminophenyl)-2-(4-aminophenyl)propane , 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1 ,3.3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 1,1 -Bis(3-aminophenyl)-1-phenylethane, 1,1-bis(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1- (4-Aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4 -Bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzyl)benzene, 1,3- Bis(4-aminobenzyl)benzene, 1,4-bis(3-aminobenzyl)benzene, 1,4-bis(4-aminobenzyl)benzene, 1,3 -Bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3 -Amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(3-amino- α,α-Di-trifluoromethylbenzyl)benzene, 1,3-bis(4-amino-α,α-di-trifluoromethylbenzyl)benzene, 1,4-bis(3-amine base-α,α-di-trifluoromethylbenzyl)benzene, 1,4-bis(4-amino-α,α-di-trifluoromethylbenzyl)benzene, 2,6-bis(3 -aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, N,N'-bis(4-aminophenyl)terephthalamide, 9, 9-Bis(4-aminophenyl) phenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis-trifluoromethyl-4,4'- Diaminobiphenyl, 3,3'-dichloro-4,4,-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3' -Dimethyl-4,4'-diaminobiphenyl, 4,4'-bis(3-aminophenoxy base) biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy) Phenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4 -(3-Aminophenoxy)phenyl] bis[4-(4-aminophenoxy)phenyl] bis[4-(3-aminophenoxy)phenyl]ether , bis[4-(4-aminophenoxy)phenyl]ether, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-( 4-Aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis[4-(3-amino) Phenoxy)benzyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzyl]benzene, 1,4-bis[4-(3-aminophenoxy) base)benzyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzyl]benzene, 1,3-bis[4-(3-aminophenoxy) -α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4 -(3-Aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl] ] Benzene, 4,4'-bis[4-(4-aminophenoxy)benzyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α- Dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylene, 4 ,4'-bis[4-(4-aminophenoxy)phenoxy]diphenylene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3 ,3'-diamino-4,4'-diphenyloxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino -4-Biphenoxybenzophenone, 6,6,-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindene alkane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirodiindane, etc., and use selected from fluoro, A diamine obtained by substituting a part or all of the hydrogen atoms on the aromatic ring of the above-mentioned diamine with a substituent in a methyl group, a methoxy group, a trifluoromethyl group, or a trifluoromethoxy group.

These can be used individually or in mixture of 2 or more types.

The diamine residue that does not have a silicon atom and has an aliphatic ring in R ^2' of the above general formula (1-1) can be set to remove 2 amine groups from the diamine that does not have a silicon atom and has an aliphatic ring the resulting residue.

As the diamine having no silicon atom and having an aliphatic ring, for example, trans-cyclohexanediamine, trans-1,4-bismethylenecyclohexanediamine, 2,6-bis( aminomethyl)bicyclo[2,2,1]heptane, 2,5-bis(aminomethyl)bicyclo[2,2,1]heptane, and the like.

These can be used individually or in mixture of 2 or more types.

In the polyimide having the structure represented by the above general formula (1-1), in terms of improving the adhesiveness with the resin-containing layer when producing a laminate with the resin-containing layer of the hard coat layer described below, The ratio of the diamine residues having a silicon atom in the main chain is preferably 10 mol % or more of the total amount of R ^2' , more preferably 15 mol % or more, more preferably more than 15 mol %, especially preferred is more than 20 mol%. On the other hand, in R ^2' of the above-mentioned general formula (1-1), in terms of improving the peelability from the support in the manufacturing process of the polyimide film and improving the surface hardness and light transmittance, in The diamine residue having a silicon atom in the main chain is preferably less than 50 mol % of the total amount of R ^2' , more preferably 45 mol % or less, and still more preferably 40 mol % or less.

Furthermore, if 2.5 mol% or more and 50 mol% or less of the total amount of R ^2' is satisfied, it is a diamine residue having a silicon atom in the main chain, and 50 mol% or more of the total amount of R ² ' is satisfied and 97.5 mol% or less are diamine residues that do not have a silicon atom and have an aromatic ring or aliphatic ring, it does not prevent R ^2' of the above general formula (1-1) from containing a silicon atom in the main chain. A diamine residue and other diamine residues different from those having no silicon atom and having an aromatic ring or an aliphatic ring. The other diamine residues are preferably 10 mol% or less of the total amount of R ^2' , more preferably 5 mol% or less, more preferably 3 mol% or less, particularly preferably 1 mol% or less. As this other diamine residue, the diamine residue etc. which do not have a silicon atom and do not have an aromatic ring or an aliphatic ring are mentioned, for example. Moreover, it is preferable not to contain the diamine residue which has 3 or more silicon atoms in a main chain from the viewpoint of improving the tensile modulus of elasticity and improving the surface hardness.

Among them, it is preferable that 2.5 mol % or more and 50 mol % or less of the total amount of R ^2' is a diamine residue having a silicon atom in the main chain, and the total amount of R ^2' (100 mol %) Among them, the remainder (100%-x%) of the above-mentioned molar % (x mol %) of the diamine residues having silicon atoms in the main chain is 50 mol % or more and 97.5 mol % or less does not have silicon atoms And have an aromatic ring or aliphatic ring diamine residue.

As the polyimide containing a silicon atom, a polyimide having a structure represented by the following general formula (1) is also preferred.

(In general formula (1), R ¹ represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group of a diamine residue, and the total amount of R ² 10 mol% or more and 50 mol% or less are diamine residues with 1 or 2 silicon atoms in the main chain, 50 mol% or more and 90 mol% or less are no silicon atoms and aromatic Diamine residue of ring or aliphatic ring; n represents the number of repeating units).

As the tetracarboxylic acid residue in R ¹ of the above-mentioned general formula (1), the same ones as the tetracarboxylic acid residue in R ^1' of the above-mentioned general formula (1-1) can be mentioned.

The diamine residue having 1 or 2 silicon atoms in the main chain in R ² of the above general formula (1) can be set to remove 2 amines from the diamine having 1 or 2 silicon atoms in the main chain residues obtained from the base. By introducing a specific amount of soft molecular skeleton with 1 or 2 silicon atoms in the main chain between the molecular skeleton containing an aromatic ring or an aliphatic ring, which is the main component of the polyimide film, the alignment is easily suppressed, The concentration of silicon atoms on the front and back sides of the polyimide film can be easily made different from each other, and further, the birefringence can easily be reduced. In addition, when the polyimide has the above-mentioned molecular skeleton, the elasticity of the polyimide film can be suppressed by introducing a specific amount of the above-mentioned specific soft molecular skeleton with short main chain into the rigid molecular skeleton. The modulus decreases at room temperature, so the surface hardness sufficient as a protective film can be maintained even at room temperature. Furthermore, when the polyimide has the molecular skeleton as described above, the bending resistance can be improved, and not only the resilience after repeated bending of the film, that is, the dynamic bending resistance, but also the long-term durability of the film can be improved. The resilience after the folded state, that is, the static bending resistance, can be used more suitably for flexible displays.

As a diamine which has one silicon atom in a main chain, the diamine represented by the following general formula (A-1) in which k=0 among the diamines represented by the said general formula (A) is mentioned, for example. Moreover, as a diamine which has two silicon atoms in a main chain, the diamine represented by the following general formula (A-2) in which k=1 in the diamine represented by the said general formula (A) is mentioned, for example.

(In general formula (A-1) and general formula (A-2), L is each independently a direct bond or -O- bond, and R ¹⁰ each independently represents that it may have a substituent and may contain an oxygen atom or a nitrogen atom The carbon number of 1 to 20 is a monovalent hydrocarbon group; R ¹¹ independently represents a divalent hydrocarbon group with a carbon number of 1 or more and 20 or less, which may have a substituent and may contain an oxygen atom or nitrogen atom; a plurality of L, R ¹⁰ and R ¹¹ may be the same or different, respectively).

The molecular weight of the diamine residue having 1 or 2 silicon atoms in the main chain is preferably 1 in terms of bending resistance and surface hardness, and in terms of easily uneven distribution of silicon atoms in the polyimide film. 1000 or less, more preferably 800 or less, more preferably 500 or less, particularly preferably 300 or less.

The diamine residue having one or two silicon atoms in the main chain may be used alone or in combination of two or more.

Examples of the diamine residue having no silicon atom and having an aromatic ring and the diamine residue having no silicon atom and having an aliphatic ring in R ² of the above general formula (1) include those of the general formula (1). The same diamine residue as described in R ^2' of 1-1).

In R ² of the above general formula (1), 10 mol % or more and 50 mol % or less of the total amount of R ² are diamine residues having 1 or 2 silicon atoms in the main chain, and R ² is More than 50 mol % and less than 90 mol % of the total amount are diamine residues that do not have silicon atoms and have aromatic or aliphatic rings, whereby silicon atoms in the polyimide film are easily distributed unevenly , it is easy to make the concentration of silicon atoms in the front and back sides different from each other, and can have sufficient bending resistance for flexible display applications and sufficient surface hardness as a protective film. R 2 in the above general formula (1) has one or two R ² in the main chain from the viewpoint of improving the adhesiveness with the resin-containing layer when producing a laminate with the resin-containing layer of the hard coat layer as described below. The diamine residue of the silicon atom is preferably more than 10 mol % of the total amount of R ² , more preferably 15 mol % or more, more preferably more than 15 mol %, and still more preferably 20 mol % or more . On the other hand, with respect to R ² of the above-mentioned general formula (1), in terms of improving the peelability from the support in the production process of the polyimide film, and improving the surface hardness and light transmittance, the main chain The diamine residue having one or two silicon atoms is preferably less than 50 mol % of the total amount of R ² , more preferably 45 mol % or less, and still more preferably 40 mol % or less.

Furthermore, if 10 mol% or more and 50 mol% or less of the total amount of R ² are satisfied, it is a diamine residue having 1 or 2 silicon atoms in the main chain, and 50 mol % of the total amount of R ² % or more and 90 mol % or less are diamine residues that do not have a silicon atom and have an aromatic ring or an aliphatic ring, it does not prevent R ² in the general formula (1) from containing one or more in the main chain. Diamine residues having 2 silicon atoms and other diamine residues having no silicon atoms and having different diamine residues having an aromatic ring or an aliphatic ring. The other diamine residue is preferably 10 mol % or less of the total amount of R ² , more preferably 5 mol % or less, more preferably 3 mol % or less, particularly preferably 1 mol % or less. As this other diamine residue, the diamine residue etc. which do not have a silicon atom and do not have an aromatic ring or an aliphatic ring are mentioned, for example. Moreover, it is preferable not to contain the diamine residue which has 3 or more silicon atoms in a main chain from the viewpoint of improving the tensile modulus of elasticity and improving the surface hardness.

Among them, it is preferable that more than 10 mol % and less than 50 mol % of the total amount of R ² are diamine residues having 1 or 2 silicon atoms in the main chain, and the total amount of R ² (100 mol % %), the remainder (100%-x%) of the above-mentioned diamine residues having 1 or 2 silicon atoms in the main chain of the molar % (x mol %) is 50 mol % or more and 90 mol % % or less are diamine residues that do not have a silicon atom and have an aromatic ring or an aliphatic ring.

The polyimide used in the present invention preferably contains an aromatic ring and is selected from the group consisting of (i) a fluorine atom and (ii) an aliphatic ring in terms of improving light transmittance and improving surface hardness. , and (iii) at least one polyimide of the group consisting of a structure in which a sulfonyl group or a fluorine-substituted alkylene group is used to connect aromatic rings to each other. When the polyimide used in the present invention contains at least one selected from the group consisting of a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, the molecular skeleton becomes rigid and the orientation is improved, and The surface hardness increases, but the rigid aromatic ring skeleton tends to extend the absorption wavelength to long wavelengths, and the transmittance in the visible light region tends to decrease.

When the (i) fluorine atom is contained in the polyimide, since the electron state in the polyimide skeleton can be made difficult to transfer charge, the light transmittance is improved.

When the polyimide contains (ii) an aliphatic ring, the transfer of charges in the skeleton can be inhibited by cutting off the conjugation of π electrons in the skeleton of the polyimide, so that the light transmittance is improved.

If the polyimide contains a structure in which aromatic rings are connected to each other by a sulfonyl group or an alkylene group which can be substituted with fluorine, the π electrons in the polyimide skeleton can be cut off by cutting off the structure. Conjugation hinders the transfer of charges in the skeleton, so the light transmittance is improved.

Among the polyimides used in the present invention, those containing fluorine atoms are preferably used in terms of improving the light transmittance and surface hardness, and in terms of improving the peelability of the coating film from the support. Polyimide. Moreover, when the polyimide which has the structure represented by the said General formula (1) contains a fluorine atom, there exists a tendency for the adhesiveness of a polyimide film and a resin containing layer to improve further.

Regarding the content ratio of fluorine atoms, the ratio (F/C) of the number of fluorine atoms (F) to the number of carbon atoms (C) obtained by measuring the surface of the polyimide by X-ray photoelectron spectroscopy (F/C) is preferably 0.01 or more, More preferably, it is 0.05 or more, and more preferably 0.1 or more. On the other hand, if the content ratio of fluorine atoms is too high, the inherent heat resistance of polyimide, etc. may be lowered. Therefore, the ratio of the number of fluorine atoms (F) to the number of carbon atoms (C) (F/C) ) is preferably 1.0 or less, more preferably 0.8 or less.

Here, the above ratio measured by X-ray photoelectron spectroscopy (XPS) can be obtained from the atomic % value of each atom measured using an X-ray photoelectron spectroscopy apparatus (eg, Theta Probe of Thermo Scientific Corporation).

Moreover, regarding the polyimide used in the present invention, in terms of improving the surface hardness, when the total of the tetracarboxylic acid residues and the diamine residues is 100 mol %, the polyimide has an aromatic ring. The total of the tetracarboxylic acid residue and the diamine residue having an aromatic ring is preferably 50 mol % or more, more preferably 60 mol % or more, and more preferably 75 mol % or more.

In addition, it is preferable that the polyimide used in the present invention contains at least one of a tetracarboxylic acid residue and a diamine residue which do not have a silicon atom, in terms of improving surface hardness and light transmittance. The aromatic ring and the fluorine atom, and more preferably both the tetracarboxylic acid residue and the diamine residue which do not have a silicon atom contain an aromatic ring and a fluorine atom.

Regarding the polyimide used in the present invention, in terms of improving surface hardness and light transmittance, when the total of tetracarboxylic acid residues and diamine residues is 100 mol %, it is preferably The total of the tetracarboxylic acid residues having an aromatic ring and a fluorine atom and the diamine residues having an aromatic ring and a fluorine atom is 50 mol % or more, more preferably 60 mol % or more, more preferably 75 mol % ear % or more.

In addition, as for the polyimide used in the present invention, it is preferable to use 50% of the hydrogen atoms bonded to the carbon atoms contained in the polyimide in terms of improving the light transmittance and improving the surface hardness. The above are polyimides directly bonded to hydrogen atoms of aromatic rings. The ratio of the hydrogen atoms (number) directly bonded to the aromatic ring among all the hydrogen atoms (number) bonded to the carbon atoms contained in the polyimide is further preferably 60% or more, more preferably 70% %above.

In the case of polyimide in which more than 50% of the hydrogen atoms bonded to carbon atoms contained in the polyimide are directly bonded to the hydrogen atoms of the aromatic ring, even after a heating step in the atmosphere, such as Extending at 200° C. or higher is preferable in that there is little change in optical properties, especially total light transmittance or yellowness YI value. In the case of polyimide in which 50% or more of hydrogen atoms bonded to carbon atoms contained in polyimide are directly bonded to hydrogen atoms of an aromatic ring, it is presumed that the reactivity with oxygen is low. Therefore, the chemical structure of polyimide is not easily changed. Polyimide film utilizes its high heat resistance and is often used in equipment that requires processing steps accompanied by heating, and more than 50% of hydrogen atoms bonded to carbon atoms contained in polyimide are direct bonds. In the case of the polyimide bonded to the hydrogen atom of the aromatic ring, there is an advantage in that it is not necessary to carry out the subsequent steps in an inactive environment to maintain transparency, so that the cost of equipment and the cost of environmental control can be suppressed.

Here, the ratio of the hydrogen atoms (number) directly bonded to the aromatic ring among all the hydrogen atoms (number) bonded to the carbon atoms contained in the polyimide can be used for the decomposition product of the polyimide. It was calculated|required using the high performance liquid chromatography, the gas chromatography mass spectrometer, and NMR. For example, the sample is decomposed with an alkaline aqueous solution or supercritical methanol, the obtained decomposed product is separated by high performance liquid chromatography, and each peak of the separation is characterized by gas chromatography mass spectrometer and NMR. The ratio of hydrogen atoms (number) directly bonded to the aromatic ring among all hydrogen atoms (number) contained in the polyimide can be obtained by analyzing and quantifying by high performance liquid chromatography .

Regarding R ^1' of the polyimide having the structure represented by the above general formula (1-1), and R ¹ of the polyimide having the structure represented by the above general formula (1), among them, the light transmittance From the aspect, the aspect of bending resistance and surface hardness, and the aspect that the silicon atoms in the film are easily distributed unevenly, it is preferably selected from the group consisting of cyclohexanetetracarboxylic dianhydride residues, cyclopentanetetracarboxylic dianhydride Residues, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride residues, cyclobutanetetracarboxylic dianhydride residues, pyromic acid dianhydride residues, 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, 2,2',3,3'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylidene)di Phthalic anhydride residues, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residues, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride residues At least one tetravalent group in the group consisting of a 4,4'-oxydiphthalic anhydride residue, and a 3,4'-oxydiphthalic anhydride residue.

In the above-mentioned R ^1' and the above-mentioned R ¹ , it is preferable that these suitable residues are contained in a total of 50 mol% or more, more preferably 70 mol% or more, and more preferably 90 mol% or more.

In particular, in terms of a good balance between light transmittance and surface hardness, R ^1' in the above general formula (1-1) and R ¹ in the above general formula (1) are more preferably selected from 4,4' -(hexafluoroisopropylidene)diphthalic anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene) propyl) at least 1 of the group consisting of diphthalic anhydride residues, 4,4'-oxydiphthalic anhydride residues, and 3,4'-oxydiphthalic anhydride residues A tetravalent base.

As R ^1' in the above-mentioned general formula (1-1) and R ¹ in the above-mentioned general formula (1), for example, a residue of pyromelic acid dianhydride, a 3,3',4,4'-linked A group of tetracarboxylic acid residues suitable for improving rigidity ( Group A) with groups such as those selected from the group consisting of cyclohexanetetracarboxylic dianhydride residues, cyclopentanetetracarboxylic dianhydride residues, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride Residues, Residues of Cyclobutane Tetracarboxylic Dianhydride, Residues of 4,4'-(Hexafluoroisopropylidene) Diphthalic Anhydride, Residues of 3,4'-(Hexafluoroisopropylidene) Di Phthalic anhydride residues, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride residues, 4,4'-oxydiphthalic anhydride residues, and 3,4' It is also preferable that at least one of the tetracarboxylic acid residue group (group B) suitable for improving light transmittance is mixed and used among the group consisting of -oxydiphthalic anhydride residues. In this case, the content ratio of the above-mentioned tetracarboxylic acid residue group (group A) suitable for improving rigidity and tetracarboxylic acid residue group (group B) suitable for improving light transmittance is relative to that suitable for The tetracarboxylic acid residue group (group B) for improving light transmittance is 1 mol, and the above-mentioned tetracarboxylic acid residue group (group A) suitable for improving rigidity is preferably 0.05 mol or more and 9 mol or less, More preferably, it is 0.1 mol or more and 5 mol or less, and more preferably 0.3 mol or more and 4 mol or less.

Among them, as the above-mentioned group B, it is preferable to use a fluorine atom-containing 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue from the viewpoint of improving surface hardness and light transmittance at least one of 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residues.

Regarding the diamine residue having an aromatic ring or an aliphatic ring in R ^2' in the above general formula (1-1), and the diamine residue having an aromatic ring or aliphatic ring in R ² in the above general formula (1) The diamine residue of the ring is preferably selected from trans-cyclohexanedicarbonate in terms of light transmittance, bending resistance and surface hardness, and the fact that silicon atoms in the film tend to be unevenly distributed. Amine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenyl residues, 3,4'-diaminodiphenyl residues Residue, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane residue, and divalent group represented by the following general formula (2) At least one kind of divalent group in the formed group is further preferably selected from the group consisting of 4,4'-diaminodiphenyl residues, 3 , 4'-diaminodiphenyl residue, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane residue, and the following At least one kind of divalent group in the group consisting of the divalent group represented by the general formula (2). As a divalent group represented by the following general formula (2), it is more preferable that R ³ and R ⁴ are perfluoroalkyl groups.

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or a perfluoroalkyl group).

In addition, about the diamine residue having a silicon atom in the main chain of R ^2' in the above general formula (1-1), and the R ² in the above general formula (1) having one or more in the main chain The diamine residue of 2 silicon atoms is preferably one having 2 silicon atoms in terms of light transmittance, bending resistance and surface hardness, and the point that the silicon atoms in the film are liable to be unevenly distributed. A diamine residue, and further, from the viewpoints of availability, light transmittance and surface hardness, 1,3-bis(3-aminopropyl)tetramethyldisiloxane residues are preferred, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, 1,3-bis(5-aminopentyl)tetramethyldisiloxane, etc.

n' in the structure represented by the above general formula (1-1) and n in the structure represented by the above general formula (1) respectively represent the number of repeating units, and are 1 or more.

In order to exhibit the following preferable glass transition temperature, the number of repeating units in the polyimide is preferably appropriately selected according to the structure, and is not particularly limited.

The average number of repeating units is usually 10 to 2000, more preferably 15 to 1000.

In addition, the polyimide used in the present invention may have a structure represented by the above-mentioned general formula (1-1) and the above-mentioned general formula (1) in a part thereof within a range not to impair the effect of the present invention. A structure that represents a different structure. In the polyimide used in the present invention, the structure represented by the general formula (1-1) or the structure represented by the general formula (1) is preferably the total repeating unit of the polyimide used in the present invention 95% or more of the number, more preferably 98% or more, more preferably 100%.

As a structure different from the structure represented by the above-mentioned general formula (1-1) and the structure represented by the above-mentioned general formula (1), for example, when a tetracarboxylic acid residue having no aromatic ring or aliphatic ring is contained, etc. etc., polyamide structure can be mentioned.

Examples of the polyamide structure that can be contained include a polyamide imide structure containing a tricarboxylic acid residue such as 1,2,4-tricarboxylic acid anhydride, or a dicarboxylic acid residue such as terephthalic acid. based on the polyamide structure.

The polyimide used in the present invention preferably has a glass transition temperature in a temperature range of 150°C or higher and 400°C or lower. Since the said glass transition temperature is 150 degreeC or more, it is excellent in heat resistance, and it is more preferable that it is 200 degreeC or more. Moreover, since the glass transition temperature is 400°C or lower, the baking temperature can be lowered, and further, it is preferably 380°C or lower.

In addition, the polyimide used in the present invention preferably does not have the peak of the tanδ curve in the temperature range of -150°C or higher and 0°C or lower, whereby the stretching of the polyimide film at room temperature can be improved. Modulus of elasticity, which can improve surface hardness. In addition, the polyimide used in the present invention may have a peak of the tanδ curve in a temperature range exceeding 0°C and less than 150°C, but it is easy to improve the tensile modulus of elasticity and the bending resistance. In other words, it is preferable to have the apex of the peak of the tanδ curve only in the temperature region of 150°C or higher. In the above-mentioned tanδ curve, if the apex of the wave peak exists below 150°C, there is a concern that the molecular chain of polyimide is likely to move, plastic deformation is likely to occur, and the bending resistance is deteriorated. When the apex of the wave peak does not exist at a temperature lower than 150°C, the mobility of the molecular chain is suppressed, plastic deformation is less likely to occur, and bending resistance is easily improved.

The glass transition temperature of the polyimide used in the present invention can be measured in the same manner as the glass transition temperature of the polyimide film described below.

2. Additives

In addition to the above-mentioned polyimide, the polyimide film of the present invention may further contain additives as necessary. Examples of the above-mentioned additives include inorganic particles, silica fillers for smooth winding, and surfactants for improving film-forming properties and defoaming properties.

3. Characteristics of polyimide film

The polyimide film of the present invention preferably has the above-mentioned specific total light transmittance, the above-mentioned specific tensile modulus of elasticity, and the above-mentioned specific yellowness. Furthermore, the polyimide film of the present invention preferably has the following properties.

In the polyimide film of the present invention, the pencil hardness is preferably 2B or more, more preferably B or more, and more preferably HB or more.

The pencil hardness of the above-mentioned polyimide film can be measured by using the test specified in JIS-S-6006 after adjusting the humidity of the measurement sample at a temperature of 25°C and a relative humidity of 60% for 2 hours. The pencil hardness test (0.98N load) specified in JIS K5600-5-4 (1999) was performed on the film surface with a pencil, and the highest pencil hardness without damage was evaluated. For example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

In terms of light transmittance, the haze value of the polyimide film of the present invention is preferably 10 or less, more preferably 8 or less, and more preferably 5 or less. The haze value can preferably be achieved when the thickness of the polyimide film is 5 μm or more and 100 μm or less.

The above-mentioned haze value can be measured by a method according to JIS K-7105, for example, can be measured by a haze meter HM150 manufactured by Murakami Color Technology Laboratory.

Furthermore, in the polyimide film of the present invention, when the adhesiveness test is performed on the surface having a relatively large silicon atom concentration according to the following adhesiveness test method, the adhesiveness between the polyimide film and the resin-containing layer is determined. It is preferable that peeling of a coating film does not generate|occur|produce in the aspect of the property and the aspect of the surface hardness of the laminated body which adjoins the polyimide film pre-lamination resin containing layer.

[Adhesion test method]

1-Hydroxy-cyclohexyl-phenyl-ketone was added to a 40% by weight solution of neotaerythritol triacrylate in methyl isobutyl ketone in an amount of 10 parts by weight based on 100 parts by weight of neotaerythritol triacrylate. A resin composition for adhesion evaluation was prepared, and the resin composition was coated on a test piece cut into a polyimide film of 10 cm × 10 cm, and was cured by irradiating ultraviolet rays at an exposure amount of 200 mJ/cm ² under nitrogen flow. , thereby forming a cured film with a thickness of 10 μm. The cured film was subjected to the cross-cut test in accordance with JIS K 5600-5-6, and the peeling operation with the tape was repeatedly performed 5 times, and then the presence or absence of peeling of the coating film was observed.

In the polyimide film of the present invention, in terms of excellent bending resistance, in the case of performing a static bending test according to the following static bending test method, the inner angle measured by the test is preferably 120° or more, More preferably, it is 125° or more.

[Static bending test method]

Bend the test piece cut into a 15mm×40mm polyimide film at the position of half of the long side, and clamp a metal sheet with a thickness of 6mm (100mm×30mm) from the top and bottom of the two ends of the long side of the test piece. ×6mm), and in a state where the two ends of the test piece and the overlapping parts of the upper and lower sides of the metal sheet are respectively 10mm with adhesive tape, use a glass plate (100mm × 100mm × 0.7 mm) was clamped from the top and bottom, and the test piece was fixed in a state of being bent with an inner diameter of 6 mm. At this time, a dummy test piece was sandwiched between the metal sheet and the glass plate where the test piece did not exist, and was fixed with an adhesive tape so that the glass plates were parallel. After the test piece fixed in a bent state in this way was allowed to stand for 24 hours in an environment of 60±2°C and 93±2% relative humidity (RH), the glass plate and the fixing tape were removed, and the application to the The power of this test piece. Then, one end of the test piece was fixed, and the inner angle of the test piece was measured 30 minutes after the force applied to the test piece was released.

In addition, in the polyimide film of the present invention, in terms of excellent bending resistance, dynamic bending was performed in an environment of 60±2° C. and 93±2% relative humidity (RH) according to the following dynamic bending test method. In the case of a bending test, the inner angle of the test piece is preferably 155° or more, and more preferably 160° or more. Furthermore, in the polyimide film of the present invention, in terms of excellent bending resistance, dynamic bending was performed in an environment of 25±2° C. and 50±2% relative humidity (RH) according to the following dynamic bending test method. In the case of a bending test, the inner angle of the test piece is preferably 170° or more, and more preferably 175° or more.

[Dynamic bending test method]

Use tape to fix the test piece of polyimide film cut into a size of 20mm×100mm in a constant temperature and humidity test system (DMX-FS, a plane-shaped unloaded U-shaped expansion test fixture manufactured by YUASA SYSTEM). After setting the test piece in the same bending state as in the above static bending test, that is, the distance between the two ends of the long side of the test piece in the bending state is 6 mm (fixed in a state of bending with an inner diameter of 6 mm), the test piece is set at 60±2 Under the environment of ℃, 93±2% relative humidity (RH), or under the environment of 25±2℃, 50±2% relative humidity (RH), repeatedly bend 200,000 times with 90 bending times in 1 minute.

Then, the test piece was taken out, one end of the obtained test piece was fixed, and the inner angle of the test piece 30 minutes after being repeatedly bent 200,000 times was measured.

In terms of heat resistance, the polyimide film of the present invention preferably has a glass transition temperature in a temperature range of 150°C or higher and 400°C or lower, and more preferably 200°C or higher, so that the baking temperature can be lowered. Specifically, it is preferably 380°C or lower.

In addition, the above-mentioned glass transition temperature is obtained from the peak temperature of the temperature-tanδ (tanδ = loss elastic modulus (E")/storage elastic modulus (E')) curve obtained by dynamic viscoelasticity measurement. The glass transition temperature of the polyimide film refers to the peak temperature where the maximum value of the peak is the maximum when there are multiple peaks of the tanδ curve.

The dynamic viscoelasticity measurement can be performed, for example, with a dynamic viscoelasticity measuring apparatus RSA III (TA Instruments Japan Co., Ltd.), with a measurement range of -150° C. to 400° C., a frequency of 1 Hz, and a temperature increase rate of 5° C./min. In addition, the sample width can be set to 5 mm, and the distance between the chucks can be set to 20 mm, and can be measured.

In the present invention, the so-called peak of the tanδ curve refers to an inflection point with a maximum value and the peak width between the concave part and the concave part of the wave peak is 3°C or more, and the slight up and down fluctuations caused by measurement such as noise are not considered. Interpreted as the above peaks.

Moreover, it is preferable that the polyimide film of this invention does not have the peak of a tan delta curve in the temperature range of -150 degreeC or more and 0 degreeC or less. In the case of a diamine residue having a long siloxane bond in the main chain, there is a peak of the tanδ curve in such a low temperature region, and a polymer such as a diamine residue having a long siloxane bond in the main chain Compared with the imide film, the lowering of the tensile modulus of elasticity at room temperature is suppressed, and the surface hardness sufficient as a protective film can be maintained.

In addition, the polyimide film of the present invention preferably has the apex of the peak of the tanδ curve only in the temperature region of 150° C. or higher, in terms of easily improving the tensile modulus of elasticity and bending resistance.

Moreover, in the polyimide film of the present invention, the birefringence in the thickness direction at the wavelength of 590 nm is preferably 0.020 or less from the viewpoint of reducing optical strain. Thereby, when the polyimide film of the present invention is used as a surface material for a display, the deterioration of the display quality of the display can be suppressed. The birefringence in the thickness direction at the wavelength of 590 nm is preferably smaller, preferably 0.015 or less, more preferably 0.010 or less, and more preferably less than 0.008.

Furthermore, the birefringence in the thickness direction of the polyimide film of the present invention at the wavelength of 590 nm can be determined as follows.

First, using a retardation measuring device (for example, Oji Scientific Instruments Co., Ltd., product name "KOBRA-WR"), the retardation value (Rth) in the thickness direction of the polyimide film with light at 25°C and a wavelength of 590 nm is used. Take measurements. The thickness direction retardation value (Rth) is measured by the retardation value of 0-degree incidence and the retardation value of 40-degree oblique incidence, and the thickness direction retardation value Rth is calculated from these retardation values. The retardation value of the above-mentioned 40-degree oblique incidence was measured by making light having a wavelength of 590 nm incident on the retardation film from a direction inclined by 40 degrees with respect to the normal line of the retardation film.

The birefringence in the thickness direction of the polyimide film can be obtained by substituting it into the formula: Rth/d. The above d represents the film thickness (nm) of the polyimide film.

Furthermore, the retardation value in the thickness direction is based on the refractive index of the slow axis direction in the in-plane direction of the film (the direction in which the refractive index in the in-plane direction of the film is the largest) as nx, and the fast axis direction in the in-plane direction of the film ( When the refractive index in the in-plane direction of the film with the smallest refractive index) is set as ny, and the refractive index in the thickness direction of the film is set as nz, it can be expressed as Rth[nm]={(nx+ny)/2- nz}×d.

As another preferred form, the ratio (F/C) of the number of fluorine atoms (F) to the number of carbon atoms (C) on the surface of the polyimide film measured by X-ray photoelectron spectroscopy is preferably 0.01 or more and 1.0 or less, more preferably 0.05 or more and 0.8 or less, more preferably 0.1 or more and 0.8 or less. Moreover, it is preferable that these conditions are satisfied on both surfaces of the polyimide film.

In addition, the ratio (F/N) of the number of fluorine atoms (F) to the number of nitrogen atoms (N) on the film surface of the polyimide film measured by X-ray photoelectron spectroscopy is preferably 0.1 or more and 20 or less. , and more preferably 0.5 or more and 15 or less.

In addition, the ratio (F/Si) of the number of fluorine atoms (F) to the number of silicon atoms (Si) on the film surface of the polyimide film measured by X-ray photoelectron spectroscopy is preferably 1 or more and 50 or less , and more preferably 3 or more and 30 or less.

4. Composition of polyimide film

The thickness of the polyimide film of the present invention may be appropriately selected according to the application, and is preferably 1 μm or more, more preferably 5 μm or more, and more preferably 10 μm or more. On the other hand, it is preferably 200 μm or less, more preferably 150 μm or less, and more preferably 100 μm or less.

When the thickness is thin, the strength decreases and it is easy to break, and when the thickness is thick, the difference between the inner diameter and the outer diameter at the time of bending increases, the load on the film increases, and the bending resistance decreases.

Furthermore, the polyimide film of the present invention may be subjected to surface treatments such as saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet treatment, and flame treatment.

5. Manufacturing method of polyimide film

The method for producing the polyimide film of the present invention is not particularly limited as long as it is a method capable of producing the above-mentioned polyimide film of the present invention. For example, the first production method includes a polyimide film comprising the following steps. A method for producing an amine film: preparing a polyimide precursor resin composition containing a silicon atom-containing polyimide precursor and an organic solvent (hereinafter, referred to as the step of preparing the polyimide precursor resin composition); The above-mentioned polyimide precursor resin composition is coated on the support and dried to form a polyimide precursor resin coating film (hereinafter, referred to as the polyimide precursor resin coating film forming step); the The above-mentioned polyimide precursor resin coating film is peeled off from the above-mentioned support (hereinafter, referred to as a peeling step); And by heating the above-mentioned polyimide precursor resin coating film, the above-mentioned polyimide precursor The imidization (hereinafter, referred to as the imidization step).

In the above-mentioned first production method, a step of coating the above-mentioned polyimide precursor resin coating film after the above-mentioned peeling step and imidizing the above-mentioned polyimide precursor resin coating film may be further included. After imidization, at least one of the coating films is extended (hereinafter, referred to as an extension step). In particular, in terms of suppressing the shrinkage of the polyimide film and increasing the tensile modulus of elasticity, it is preferable to have a step of extending the polyimide precursor resin coating film after the peeling step.

In the above-mentioned 1st manufacturing method, the peelability of the surface of the above-mentioned polyimide precursor resin coating film in contact with the above-mentioned support is good, so the above-mentioned polyimide precursor resin coating film can be easily removed from the above-mentioned support. The body is peeled off, and it is not easy to produce defects. In the polyimide precursor resin coating film formed by the polyimide precursor resin coating film forming step, the silicon atom concentration is smaller than the surface that is in contact with the above-mentioned support and the surface that is in contact with the air, Therefore, it is easy to peel off the support.

Hereinafter, each step will be described in detail.

(1) Preparation steps of polyimide precursor resin composition

The polyimide precursor resin composition prepared in the above-mentioned first production method contains a polyimide precursor containing silicon atoms, an organic solvent, and optionally an additive.

The polyimide precursor is a polyimide obtained by the polymerization of a tetracarboxylic acid component and a diamine component. In the said 1st manufacturing method, as a precursor of the polyimide containing a silicon atom, the polyimide which becomes the said polyimide containing a silicon atom by an imidization reaction is used.

The polyimide which becomes the polyimide having the structure represented by the above general formula (1-1) by the imidization reaction is a polyimide having the structure represented by the following general formula (1-1') Amine precursors.

(In the general formula (1-1'), R ^1' , R ^2' and n' are the same as the above-mentioned general formula (1-1)).

The polyimide precursor represented by the above-mentioned general formula (1-1') is obtained by combining the tetracarboxylic acid component that becomes the tetracarboxylic acid residue in R ^1' of the above-mentioned general formula (1-1') with the above-mentioned general formula. Polyamic acid obtained by polymerization of the diamine component of the diamine residue in R ^2' of formula (1-1').

Here, R ^1' , R ^2' and n' of the above general formula (1-1') can be used as R ^1' and R ² of the above general formula (1-1) described in the above polyimide ^' and n' are the same.

The polyimide precursor which becomes the polyimide having the structure represented by the above-mentioned general formula (1) by the imidization reaction is a polyimide precursor having the structure represented by the following general formula (1').

(In the general formula (1'), R ¹ , R ² and n are the same as the above-mentioned general formula (1)).

The polyimide precursor represented by the above-mentioned general formula (1') is obtained by combining the tetracarboxylic acid component that becomes the tetracarboxylic acid residue in R ¹ of the above-mentioned general formula (1') with the above-mentioned general formula (1') The polyamide acid obtained by the polymerization of the diamine component of the diamine residue in R ² .

Here, R ^{1 , R 2 and n of the above general formula (1′) can be used for the same ones as R 1 , R 2 and n} of the above general formula (1) described in the above-mentioned polyimide.

The polyimide precursor represented by the above general formula (1-1') and the polyimide precursor represented by the above general formula (1') are preferably the quantity in terms of strength at the time of film formation At least one of the average molecular weight or the weight average molecular weight is 10,000 or more, more preferably 20,000 or more. On the other hand, if the average molecular weight is too large, the viscosity will be high, and the workability of filtration and the like may be lowered.

The number-average molecular weight of the polyimide precursor can be determined by NMR (eg, AVANCE III manufactured by BRUKER). For example, after coating the polyimide precursor solution on a glass plate and drying at 100° C. for 5 minutes, 10 mg of the solid content is dissolved in 7.5 ml of dimethyl sulfoxide-d6 solvent, and NMR measurement is performed. The number average molecular weight was calculated from the peak intensity ratio of the hydrogen atoms of the aromatic ring.

The weight average molecular weight of the polyimide precursor can be measured by gel permeation chromatography (GPC). For example, the polyimide precursor is prepared as an N-methylpyrrolidone (NMP) solution with a concentration of 0.5 wt %, and the developing solvent is a 10 mmol% LiBr-NMP solution with a water content of 500 ppm or less, and a solution manufactured by Tosoh is used. A GPC apparatus (HLC-8120, using a column: GPC LF-804 manufactured by SHODEX) was measured under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL/min, and 40°C. The weight-average molecular weight was determined on the basis of a polystyrene standard sample having the same concentration as the sample.

The said polyimide precursor solution is obtained by making the said tetracarboxylic dianhydride and the said diamine react in a solvent. The solvent used in the synthesis of the polyimide precursor (polyimide) is not particularly limited as long as it can dissolve the above-mentioned tetracarboxylic dianhydride and diamine. For example, an aprotic polar solvent or a water-soluble solvent can be used. Alcohol-based solvents, etc. In the present invention, it is particularly preferable to use N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylidene Nitrogen-containing organic solvents such as phosphoramide, 1,3-dimethyl-2-imidazolidinone, etc.; γ-butyrolactone, etc. Wherein, when the above-mentioned polyimide precursor solution (polyimide solution) is directly used in the preparation of the polyimide precursor resin composition, it is preferable to use an organic solvent containing nitrogen atoms, wherein, It is preferred to use N,N-dimethylacetamide, N-methyl-2-pyrrolidone or a combination of these. In addition, the so-called organic solvent means a solvent containing a carbon atom.

In addition, the above-mentioned polyimide precursor solution is prepared by combining at least two kinds of diamines, and acid dianhydrides may be added to the mixed solution of at least two kinds of diamines to synthesize polyimide, or at least two kinds of diamines may be combined The amine component is added stepwise to the reaction liquid at an appropriate molar ratio, and the order in which each raw material is incorporated into the polymer chain is controlled to a certain extent.

For example, by adding 0.5 equivalent molar ratio of acid dianhydride to the diamine having a silicon atom in the main chain into a reaction solution in which the diamine having a silicon atom in the main chain is dissolved and reacting it, the acid Both ends of the dianhydride are synthesized from a diamine having a silicon atom in the main chain to react with the aramidic acid, all or a part of the remaining diamine is put into the solution, and acid dianhydride is added to polymerize the polyamic acid. When polymerizing by this method, the diamine which has a silicon atom in a main chain is introduce|transduced into a polyamide acid in the form connected by one acid dianhydride.

It is preferable to use this method to polymerize polyamide in terms of specifying the positional relationship of amides having silicon atoms in the main chain to some extent, maintaining surface hardness, and easily obtaining a film excellent in bending resistance. .

When the molar number of diamine in the above-mentioned polyimide precursor solution (polyamide acid solution) is set to X and the molar number of tetracarboxylic dianhydride to Y, it is preferable to set Y/X It is 0.9 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less, still more preferably 0.97 or more and 1.03 or less, and still more preferably 0.99 or more and 1.01 or less. The molecular weight (polymerization degree) of the polyamic acid obtained by setting it as such a range can be adjusted suitably.

The order of the polymerization reaction can be appropriately selected from a known method and used, and is not particularly limited.

In addition, the polyimide precursor solution obtained by the synthesis reaction can be used as it is, and other components can be mixed with it as needed, or the solvent of the polyimide precursor solution can be dried and dissolved in other solvents for use.

In terms of forming a uniform coating film and polyimide film, the viscosity of the polyimide precursor solution at 25° C. is preferably 500 cps or more and 200,000 cps or less.

The viscosity of the polyimide precursor solution can be measured at 25°C using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.).

The above-mentioned polyimide precursor resin composition may also contain additives as required. As the above-mentioned additives, for example, inorganic particles, silica fillers for smooth winding, surfactants for improving film-forming properties and defoaming properties, etc., can be used as described in the above-mentioned polyimide film the same additives.

The organic solvent used in the above-mentioned polyimide precursor resin composition is not particularly limited as long as it can dissolve the above-mentioned polyimide precursor. For example, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphamide, 1 , 3-dimethyl-2-imidazolidinone and other organic solvents containing nitrogen atoms; γ-butyrolactone and the like, among which, organic solvents containing nitrogen atoms are preferably used.

In terms of forming a polyimide film having a uniform coating film and a strength capable of being handled, the content of the polyimide precursor in the above-mentioned polyimide precursor resin composition is preferably in the resin composition. The solid content of the composition is 50% by weight or more, more preferably 60% by weight or more, and the upper limit may be appropriately adjusted according to the contained components.

In terms of forming a uniform coating film and polyimide film, the organic solvent in the above-mentioned polyimide precursor resin composition is preferably 40% by weight or more in the resin composition, and more preferably 50% by weight. % by weight or more, and preferably 99% by weight or less.

In addition, the polyimide precursor resin composition preferably has a water content of 1000 ppm or less in terms of good storage stability and improved productivity. When a large amount of water is contained in the polyimide precursor resin composition, the polyimide precursor may be easily decomposed.

In addition, the water content of a polyimide precursor resin composition can be calculated|required using a Karl Fischer moisture meter (for example, the trace moisture measuring apparatus CA-200 type|mold by Mitsubishi Chemical Co., Ltd.).

The method for preparing the above-mentioned polyimide precursor resin composition is not particularly limited, but in order to make the water content 1000 ppm or less as described above, it is preferable to dehydrate the organic solvent used, or to use a water content manager, and Handle in an environment with humidity below 5%.

In terms of forming a uniform coating film and polyimide film, the viscosity of the polyimide precursor resin composition at 25° C. is preferably 500 cps or more and 100,000 cps or less.

The viscosity of the polyimide precursor resin composition can be measured using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.) at 25° C. with a sample amount of 0.8 ml.

(2) Polyimide Precursor Resin Coating Film Formation Step

As a support used in the step of coating the above-mentioned polyimide precursor resin composition on a support to form a polyimide precursor resin coating film, any support that has a smooth surface and has heat resistance and solvent resistance There are no special restrictions on the materials. For example, inorganic materials, such as a glass plate, and the metal plate whose surface was mirror-finished, etc. are mentioned. In addition, the shape of the support body is selected according to the coating method, and for example, it may be a plate shape, a cylindrical shape, a belt shape, a sheet shape that can be wound into a roll, or the like.

The above-mentioned coating means is not particularly limited as long as it is a method capable of coating with a target film thickness. For example, a die coater, a notch coater, a roll coater, and a gravure coater can be used. , curtain coater, spray coater, die lip coater and other well-known ones.

Coating can be performed by a single-sheet type coating device, or by a roll-to-roll type coating device.

After the polyimide precursor resin composition is coated on the support, the solvent in the coating film is dried. By setting the drying temperature of the solvent to be 150° C. or lower, the imidization of the polyamic acid can be suppressed.

The drying temperature and time may be appropriately adjusted according to the film thickness of the polyimide precursor resin coating film, the type of the solvent, and the like. The drying temperature is preferably 150°C or lower, more preferably 30°C or higher and 120°C or lower.

Moreover, it is preferable to carry out the said drying, raising a temperature step by step, and it is preferable to perform it while raising a temperature step by step at least in two stages. Moreover, it is preferable to perform the said drying for 10 minutes or more in total, and it is more preferable to perform it for 20 minutes or more. It is presumed that the silicon atoms in the coating film tend to be unevenly distributed, and the difference in the concentration of silicon atoms on the front and back surfaces tends to increase. As the above drying method, specifically, for example, the following method can be preferably used: after drying at 40°C or higher and less than 70°C, more preferably at 40°C or higher and 65°C or lower for 5 to 60 minutes, then drying at 70°C for 5 to 60 minutes. ℃ or higher and 140°C or lower, more preferably 80°C or higher and 140°C or lower, and drying at a temperature higher than the previous drying by 30°C or higher for 5 minutes to 60 minutes.

If drying is performed at a high temperature from the beginning in the two stages, or drying is performed at a high temperature in the first stage for a short period of time, it may be difficult for the silicon atoms to be unevenly distributed, and there is a possibility that the film thickness unevenness of the film or the occurrence of The case of bubbles.

The drying method of the solvent is not particularly limited as long as the solvent can be dried at the above-mentioned temperature, and for example, an oven, a drying furnace, a hot plate, and infrared heating can be used.

In the case where high management of optical properties is required, the environment in which the solvent is dried is preferably an inert gas environment. In an inert gas atmosphere, preferably in a nitrogen atmosphere, the oxygen concentration is preferably 100 ppm or less, and more preferably 50 ppm or less. If the heat treatment is performed in the atmosphere, the film may be oxidized, colored, or deteriorated in performance.

(3) Peeling step

The said polyimide precursor resin coating film is peeled from the said support body after drying.

The method of peeling the above-mentioned polyimide precursor resin coating film from the above-mentioned support is not particularly limited, and a general peeling method can be used. In the present invention, since the peelability of the surface in contact with the above-mentioned support of the above-mentioned polyimide precursor resin coating film is excellent, the above-mentioned polyimide precursor resin coating film can be removed from the above-mentioned support by stretching the above-mentioned polyimide precursor resin coating film. Peel off easily.

The peeling conditions in the peeling step are not particularly limited. For example, the peeling strength of the support and the polyimide precursor resin coating film can be set to 0.05N/25mm or more and 2.0N/25mm or less, and the peeling speed can be set to 100 mm/min or more and 1,000 mm/min or less, and the peeling angle shall be 135° or more and 180° or less. The above-mentioned peeling can be carried out in the following manner, that is, starting from the open end of the support and the polyimide precursor resin coating film, and separating along the longitudinal direction of the polyimide precursor resin coating film. A virtually constant speed peel.

Moreover, in the above-mentioned first production method, in the above-mentioned peeling step, the residual solvent amount in the above-mentioned polyimide precursor resin coating film is preferably 40% by weight or less in terms of easy peeling of the support, More preferably, it is 30% by weight or less. In addition, in terms of suppressing uneven film thickness of the polyimide film and making the surface texture uniform, the amount of the residual solvent in the polyimide precursor resin coating film in the peeling step may be 10 wt. %above.

Furthermore, the residual solvent amount in the above-mentioned polyimide precursor resin coating film during the peeling step can be measured by the following method, that is, the above-mentioned polyimide precursor resin coating film immediately after the peeling step is performed. , and the integrated intensity ratio of the hydrogen atoms derived from the polyimide precursor and the hydrogen atoms derived from the solvent was obtained using ¹ H-NMR.

Moreover, in the above-mentioned first production method, in the above-mentioned peeling step, the imidization rate of the polyimide precursor resin coating film is preferably 1% or more in terms of easy peeling of the support and 50% or less, more preferably 5% or more and 30% or less.

In addition, the measurement of the imidization rate can be performed by the analysis etc. of the spectrum using infrared measurement (IR).

(4) imidization step

In the said 1st manufacturing method, the said polyimide precursor is imidized by heating the said polyimide precursor resin coating film.

Moreover, in the above-mentioned first manufacturing method, it is preferable to have an extension step, and in the case of having the above-mentioned extension step, the imidization step can be used for the polymerization of the polyimide precursor resin coating film before the extension step. The polyimide precursor can be carried out on the polyimide precursor in the above-mentioned polyimide precursor resin coating film after the extension step, or the above-mentioned polyimide precursor resin coating film before the stretching step. Both the polyimide precursor in and the polyimide precursor present in the film after the extension step were performed.

The imidization temperature may be appropriately selected according to the structure of the polyimide precursor.

Usually, it is preferable to set temperature increase starting temperature to 30 degreeC or more, and it is more preferable to set it to 100 degreeC or more. On the other hand, it is preferable to set temperature increase completion temperature to 250 degreeC or more.

The heating rate is preferably appropriately selected according to the film thickness of the obtained polyimide film, and when the film thickness of the polyimide film is relatively thick, the heating rate is preferably reduced.

It is preferable to set it as 5 degreeC/min or more from the point of the manufacturing efficiency of a polyimide film, and it is more preferable to set it as 10 degreeC/min or more. On the other hand, the upper limit of the temperature increase rate is usually 50°C/min, preferably 40°C/min or less, and more preferably 30°C/min or less. It is preferable to set it as the said temperature rise rate from the point which can suppress the defect of an external appearance of a film, fall in intensity|strength, control the whitening accompanying an imidization reaction, and improve light transmittance.

The temperature rise may be carried out continuously or in steps, but it is preferably carried out continuously in terms of suppressing poor appearance and strength reduction of the film and controlling whitening accompanying the imidization reaction. Moreover, in the said total temperature range, the temperature increase rate may be fixed, and may be changed in the middle.

The environment at the time of raising the temperature of the imidization is preferably an inert gas environment. As an inert gas atmosphere, preferably a nitrogen atmosphere, the oxygen concentration is preferably 500 ppm or less, more preferably 200 ppm or less, and still more preferably 100 ppm or less. If the heat treatment is performed in the atmosphere, the film may be oxidized, colored, or deteriorated in performance.

However, in the case where more than 50% of the hydrogen atoms bonded to carbon atoms contained in the polyimide are hydrogen atoms directly bonded to the aromatic ring, the influence of oxygen on the optical properties is small, even if inactive is not used. In the gas environment, polyimide with high light transmittance can also be obtained.

The heating method for imidization is not particularly limited as long as the temperature can be raised at the above-mentioned temperature. For example, an oven, a heating furnace, infrared heating, electromagnetic induction heating, or the like can be used.

In order to obtain the final polyimide film, it is preferable to carry out the reaction until the imidization is 90% or more, further 95% or more, and further 100%.

In order to carry out the reaction until the imidization of 90% or more, and further to 100%, it is preferable to hold the temperature at the end of temperature rise for a certain period of time. The holding time is usually 1 minute to 180 minutes, and more preferably 5 minutes to 5 minutes. 150 minutes.

(5) Extension step

The above-mentioned first production method may include extending at least one of the above-mentioned polyimide precursor resin coating film and the imidized post-imide coating film obtained by imidizing the above-mentioned polyimide precursor resin coating film extension step. Among them, in terms of suppressing the shrinkage of the polyimide film and improving the tensile modulus of elasticity, it is preferable to include the polyimide precursor resin after the peeling step and before the imidization step. The extension step of extending the coating film. Moreover, it is also preferable to further include the step of extending|stretching the coating film after imidization from the viewpoint of the surface hardness of a polyimide film.

In the said 1st manufacturing method, it is preferable to carry out the process of extending|stretching 101% or more and 10000% or less, when making the initial dimension before extending|stretching 100%, heating at 80 degreeC or more.

The heating temperature during elongation is preferably within the range of ±50°C of the glass transition temperature of the polyimide or the polyimide precursor, and more preferably within the range of ±40°C of the glass transition temperature. If the stretching temperature is too low, the film may not be deformed and the orientation may not be sufficiently induced. On the other hand, if the stretching temperature is too high, there is a concern that the alignment obtained by the stretching is moderated by the temperature and a sufficient alignment is not obtained.

The extension step can also be performed concurrently with the imidization step. When the imidized coating film is stretched with an imidization rate of 80% or more, further 90% or more, further 95% or more, and especially substantially 100%, the improvement is improved. The surface hardness of the polyimide film is preferable.

Regarding the stretching ratio of the polyimide film, the final stretching ratio is preferably 101% or more and 10000% or less, and more preferably 101% or more and 500% or less. By extending in the above-mentioned range, the shrinkage of the obtained polyimide film can be suppressed, and the tensile modulus of elasticity and the surface hardness can be further improved.

The fixing method of the polyimide film during stretching is not particularly limited, and can be selected according to the type of the stretching device. In addition, the stretching method is not particularly limited, and for example, it can be stretched while passing through a heating furnace using a stretching device having a conveying device such as a tenter. The polyimide film can be stretched only in one direction (longitudinal stretching or lateral stretching), and can also be stretched in two directions by simultaneous biaxial stretching, successive biaxial stretching, and oblique stretching. Among them, in terms of suppressing the shrinkage of the polyimide film and increasing the tensile modulus of elasticity, it is preferable to coat the polyimide precursor resin on the polyimide precursor resin after the peeling step and before the imidization step. The film is stretched in two directions.

Moreover, as the manufacturing method of the polyimide film of the present invention, the manufacturing method of the polyimide film comprising the following steps can be mentioned as the second manufacturing method: preparing a polyimide containing a silicon atom and an organic solvent. Polyimide resin composition (hereinafter, referred to as polyimide resin composition preparation step); the above-mentioned polyimide resin composition is coated on a support and the solvent is dried to form a polyimide resin coating film (hereinafter, referred to as a polyimide resin coating film forming step); and peeling the above-mentioned support from the polyimide resin coating film (hereinafter, referred to as a peeling step).

In the above-mentioned 2nd manufacturing method, because the peelability of the surface contacting with the above-mentioned support of the above-mentioned polyimide resin coating film is good, the above-mentioned polyimide resin coating film can be easily peeled off from the above-mentioned support, and it is difficult to Defects caused by peeling occur. In the polyimide resin coating film formed by the polyimide resin coating film forming step, the silicon atom concentration is smaller than the above-mentioned surface in contact with the support and the surface in contact with the air, so that the support is easily peeled off.

When the polyimide used in the present invention is satisfactorily dissolved in the organic solvent, not only the polyimide precursor resin composition but also the above-mentioned polyimide dissolved in the organic solvent can be suitably used. And optionally contain a polyimide resin composition of additives.

When the polyimide used in the present invention has a solvent solubility of 5% by weight or more in an organic solvent at 25°C, the second production method described above can be suitably used.

In the preparation step of the polyimide resin composition, the polyimide containing silicon atoms can be selected from the same polyimide as described in the above-mentioned polyimide film having the above-mentioned solvent solubility. Amines are used. As a method for carrying out imidization, it is preferable to use chemical imidization using a chemical imidizing agent instead of thermal dehydration for the dehydration ring-closure reaction of the polyimide precursor. In the case of chemical imidization, known dehydration catalysts such as amines such as pyridine and β-picolinic acid, carbodiimides such as dicyclohexylcarbodiimide, and acid anhydrides such as acetic anhydride can also be used. compound. The acid anhydride is not limited to acetic anhydride, and examples thereof include propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like, and are not particularly limited. In addition, in this case, a tertiary amine such as pyridine or β-picolinic acid may be used in combination. However, if these amines remain in the film, the optical properties, especially the yellowness (YI value), will be lowered, so it is not necessary to directly cast the reaction solution from the precursor to the polyimide to form the film. Preferably, it is purified by reprecipitation or the like, and the components other than the polyimide are respectively removed to 100 ppm or less of the total weight of the polyimide, and then the film is formed.

As the organic solvent used in the preparation step of the polyimide resin composition, the same organic solvent as described in the preparation step of the polyimide precursor resin composition in the above-mentioned first production method can be used.

The above-mentioned polyimide resin composition may also contain additives as needed. As the above-mentioned additives, the same additives as those described in the above-mentioned preparation step of the polyimide precursor resin composition in the above-mentioned first production method can be used.

In addition, as a method for setting the water content of the polyimide resin composition to be 1000 ppm or less in the second method, the same method as the process for preparing the polyimide precursor resin composition in the first method can be used. The method described in the same method.

In addition, in the polyimide resin coating film forming step in the above-mentioned second production method, the support or the coating method can be used in the polyimide precursor resin coating film forming step in the above-mentioned first production method. The same support or coating method as described.

In the polyimide resin coating film forming step in the second production method described above, the drying temperature is preferably 80° C. or higher and 150° C. or lower under normal pressure. It is preferable to set it as the range of 10 degreeC or more and 100 degrees C or less under reduced pressure.

Moreover, it is preferable to perform the drying of the polyimide resin coating-film formation process in the said 2nd manufacturing method, raising temperature stepwise in at least two stages. Moreover, it is preferable to perform the said drying for 10 minutes or more in total, and it is more preferable to perform it for 20 minutes or more. It is presumed that the silicon atoms in the coating film tend to be unevenly distributed, and the difference in the concentration of silicon atoms on the front and back surfaces tends to increase. As the drying method, the drying method preferably used in the first production method described above can also be preferably used in the second production method described above. Moreover, as a drying method of the solvent in the said 2nd manufacturing method, the method similar to the method used in the said 1st manufacturing method is mentioned.

In addition, the peeling method and peeling conditions of the peeling process in the said 2nd manufacturing method can be the same as that of the peeling process of the said 1st manufacturing method.

In the above-mentioned second production method, in terms of the ease of peeling of the support, in the above-mentioned peeling step, the residual solvent amount in the above-mentioned polyimide resin coating film is preferably 40% by weight or less, more preferably 30% by weight or less. Furthermore, in terms of suppressing uneven film thickness of the polyimide film and making the surface texture uniform, the amount of residual solvent in the polyimide resin coating film in the peeling step may be 10% by weight or more. .

Furthermore, the residual solvent amount in the above-mentioned polyimide resin coating film during the peeling step can be measured by using ¹ H for the above-mentioned polyimide resin coating film immediately after the peeling step. -NMR The integral intensity ratio of the hydrogen atom derived from polyimide and the hydrogen atom derived from a solvent was calculated|required.

Moreover, the said 2nd manufacturing method may have the extending|stretching process of extending|stretching a polyimide resin coating film after the said peeling process. The stretching step may be the same as the stretching step in the above-mentioned first manufacturing method.

Moreover, the said 2nd manufacturing method may further have the drying process for removing the residual solvent in the said polyimide resin coating film. The drying temperature and time in the drying step are not particularly limited as long as they are appropriately adjusted according to the film thickness of the polyimide resin coating film, the type of solvent, and the like, but are preferably 100°C or higher and 400°C or lower, minutes or more and 180 minutes or less. In addition, the drying step is preferably in an inert gas atmosphere from the viewpoint of suppressing the decrease in the optical properties of the polyimide film. In an inert gas atmosphere, preferably in a nitrogen atmosphere, the oxygen concentration is preferably 100 ppm or less, and more preferably 50 ppm or less.

6. Use of polyimide film

The application of the polyimide film of the present invention is not particularly limited, and it can be used as a base material or a surface material used in conventional glass products such as thin plate glass. The polyimide film of the present invention can improve bending resistance, has sufficient surface hardness as a protective film, and reduce optical strain, so it can be particularly suitably used as a display surface material that can cope with curved surfaces.

Specifically, the polyimide film of the present invention can be suitably used for, for example, thin and curved flexible organic EL displays, mobile terminals such as smartphones and watch-type terminals, display devices in automobiles, watches, and the like. Use flexible panels, etc. In addition, the polyimide film of the present invention can also be applied to components for image display devices such as liquid crystal display devices and organic EL display devices, or components for touch panels, flexible printed boards, surface protection films, or solar panels such as substrate materials. Components for cell panels, components for optical waveguides, and other semiconductor-related components.

In addition, the polyimide film of the present invention is excellent in adhesion to the surface having a relatively large concentration of silicon atoms, especially with a resin-containing layer containing a polymer containing at least one of a radically polymerizable compound and a cationically polymerizable compound. Excellent adhesion. Therefore, in the polyimide film of the present invention, the surface having a relatively large concentration of silicon atoms can be suitably used as the close contact surface with the resin-containing layer.

The resin-containing layer can be the same as the resin-containing layer used in the laminates described below, so the description here is omitted.

II. Laminate

Lamination System of the Present Invention A laminate in which the polyimide film of the present invention and a resin-containing layer containing a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound are located adjacent to each other.

In the laminate of the present invention, the adhesiveness between the polyimide film and the resin-containing layer can be improved by adhering the resin-containing layer to the surface of the polyimide film of the present invention where the silicon atom concentration is relatively high, thereby improving the adhesion between the polyimide film and the resin-containing layer. The surface hardness can also be further increased. Furthermore, since the above-mentioned polyimide film of the present invention is used in the laminate system of the present invention, the failure of the polyimide film can be suppressed, and the quality of the laminate can be suppressed from deteriorating.

Furthermore, since the polyimide film of the present invention is used in the laminate system of the present invention, the decrease in transparency can be suppressed, and further, optical strain can be reduced. Therefore, when the layered product of the present invention is used as a surface material for a display, the deterioration of the display quality of the display can be suppressed. Furthermore, since the polyimide film of the present invention is used in the laminate system of the present invention, bending resistance can be improved, and it can be suitably used for flexible displays.

1. Polyimide film

As the polyimide film used in the layered product of the present invention, the polyimide film of the present invention can be used, so the description here is omitted.

2. Resin-containing layer

The resin-containing layer used in the layered product of the present invention may contain a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound, and may further contain a polymerization initiator and other additives as necessary.

As said resin containing layer, the functional layer etc. which are used for a display are mentioned, for example, Specifically, a hard-coat layer etc. are mentioned, for example.

(1) Radically polymerizable compound

The radically polymerizable compound refers to a compound having a radically polymerizable group. The radically polymerizable group possessed by the above-mentioned radically polymerizable compound is not particularly limited as long as it is a functional group capable of generating a radical polymerization reaction, and examples thereof include a carbon-carbon unsaturated double bond-containing group, and the like. For example, vinyl group, (meth)acryloyl group, etc. are mentioned. In addition, when the said radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be respectively the same or different.

From the viewpoint of increasing the hardness of the resin-containing layer, the number of radically polymerizable groups contained in one molecule of the radically polymerizable compound is preferably 2 or more, and more preferably 3 or more.

Among the above-mentioned radically polymerizable compounds, those having a (meth)acryloyl group are preferred in terms of high reactivity, and further, in terms of the adhesiveness between the polyimide film and the resin-containing layer, and In terms of light transmittance and surface hardness, a compound having two or more (meth)acryloyl groups in one molecule is preferred. For example, a compound called a polyfunctional acrylate monomer having 2 to 6 (meth)acryloyl groups in one molecule or a compound called urethane (meth)acrylate can be preferably used. )acrylate), polyester (meth)acrylate, epoxy (meth)acrylate are oligomers with several (meth)acryloyl groups in the molecule and the molecular weight is hundreds to thousands.

In addition, in this specification, a (meth)acryloyl group refers to each of an acryl group and a methacryloyl group, and the so-called (meth)acrylate refers to each of an acrylate and a methacrylate. .

Specific examples of the radically polymerizable compound include: vinyl compounds such as divinylbenzene; ethylene glycol di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, 9, 9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]phenyl, alkylene oxide modified bisphenol A di(meth)acrylate (for example, ethoxylate) alkylated (ethylene oxide modified) bisphenol A di(meth)acrylate, etc.), trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, Neotaerythritol tri(meth)acrylate, Neotaerythritol tetra(meth)acrylate, Dipivalerythritol tri(meth)acrylate, Dipivalerythritol tetra(meth)acrylate, Polyalcohol polyacrylates such as Dipiveaerythritol penta(meth)acrylate, Dipiveaerythritol hexa(meth)acrylate, Diacrylate of Bisphenol A Diglycidyl Ether, Hexylene Glycol Epoxy acrylates such as diacrylates of diglycidyl ether, acrylates obtained by the reaction of polyisocyanates with hydroxyl-containing acrylates such as hydroxyethyl acrylate, and the like.

(2) Cationic polymerizable compound

The cationically polymerizable compound refers to a compound having a cationically polymerizable group. The cationically polymerizable group of the cationically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a cationic polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. In addition, when the said cationically polymerizable compound has two or more cationically polymerizable groups, these cationically polymerizable groups may be respectively the same or different.

From the viewpoint of improving the hardness of the resin-containing layer, the number of cationically polymerizable groups contained in one molecule of the cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more.

In addition, among the above-mentioned cationically polymerizable compounds, compounds having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group are preferable in terms of the adhesion between the polyimide film and the resin-containing layer. In terms of light transmittance and surface hardness, a compound having at least one of two or more epoxy groups and oxetanyl groups in one molecule is more preferable. A cyclic ether group such as an epoxy group and an oxetanyl group is preferable in terms of small shrinkage accompanying the polymerization reaction. In addition, the compound having the epoxy group in the cyclic ether group has the following advantages: it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained resin-containing layer, and is easy to control and radically polymerize the compound. compatibility. In addition, the oxetanyl group in the cyclic ether group has the following advantages compared with the epoxy group: the degree of polymerization is high, the toxicity is low, and when the obtained resin-containing layer is combined with the compound having an epoxy group , to speed up the formation speed of the network structure obtained by the cationic polymerizable compound in the coating film, even in the area where it is mixed with the free radical polymerizable compound, the unreacted monomer will not remain in the film, forming an independent network. like structure.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ether of a polyol having an alicyclic ring, or a cyclohexene ring-containing , Alicyclic epoxy resins obtained by epoxidizing compounds of cyclopentene rings; polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts, polypropylene oxides of aliphatic long-chain polyacids Aliphatic epoxy resins such as homopolymers and copolymers of esters, glycidyl (meth)acrylates; epoxy resins made of bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A Glycidyl ethers produced by the reaction of derivatives such as alkyl adducts and caprolactone adducts with epichlorohydrin, and glycidyl ethers derived from bisphenols such as novolak epoxy resins epoxy resin etc.

As said alicyclic epoxy resin, 3, 4- epoxy cyclohexyl methyl-3, 4- epoxy cyclohexane carboxylate (UVR-6105, UVR-6107, UVR-6110), hexane Diacid bis-3,4-epoxycyclohexyl methyl ester (UVR-6128) (above, the trade name in parentheses is the product of Dow Chemical).

Moreover, as said glycidyl ether type epoxy resin, sorbitol polyglycidyl ether (DENACOL EX-611, DENACOL EX-612, DENACOL EX-614, DENACOL EX-614B, DENACOL EX-622 ), polyglycerol polyglycidyl ether (DENACOL EX-512, DENACOL EX-521), neotaerythritol polyglycidyl ether (DENACOL EX-411), diglycerol polyglycidyl ether (DENACOL EX-421), glycerol polyglycidyl ether (DENACOL EX-313, DENACOL EX-314), trimethylolpropane polyglycidyl ether (DENACOL EX-321), resorcinol Diglycidyl Ether (DENACOL EX-201), Neopentyl Glycol Diglycidyl Ether (DENACOL EX-211), 1,6 Hexanediol Diglycidyl Ether (DENACOL EX-212), Hydrogen Dibisphenol A Diglycidyl Ether (DENACOL EX-252), Ethylene Glycol Diglycidyl Ether (DENACOL EX-810, DENACOL EX-811), Polyethylene Glycol Diglycidyl Ether (DENACOL EX-850, DENACOL EX-851, DENACOL EX-821), propylene glycol glycidyl ether (DENACOL EX-911), polypropylene glycol glycidyl ether (DENACOL EX-941, DENACOL EX-920), allyl glycidyl ether (DENACOL EX-111), 2-ethylhexyl glycidyl ether (DENACOL EX-121), phenyl glycidyl ether (DENACOL EX-141), phenol glycidyl ether ( DENACOL EX-145), Butyl phenyl glycidyl ether (DENACOL EX-146), Diglycidyl phthalate (DENACOL EX-721), Hydroquinone diglycidyl ether (DENACOL EX-203), diglycidyl terephthalate (DENACOL EX-711), glycidyl phthalimide (DENACOL EX-731), dibromophenylglycidyl ether (DENACOL EX-147), dibromoneopentyl glycol diglycidyl ether (DENACOL EX-221) (above, the trade name in parentheses is the product of Nagase ChemteX).

Moreover, as other commercially available epoxy resins, Epikote 825, Epikote 827, Epikote 828, Epikote 828EL, Epikote 828XA, Epikote 834, Epikote 801, Epikote 801P, Epikote 802, Epikote 815, Epikote 815XA, Epikote 816A、Epikote 819、Epikote 834X90、Epikote 1001B80、Epikote 1001X70、Epikote 1001X75、Epikote 1001T75、Epikote 806、Epikote 806P、Epikote 807、Epikote 152、Epikote 154、Epikote 871、Epikote 191P、Epikote YX310、Epikote DX255、Epikote YX8000 , Epikote YX8034, etc. (the above are trade names, manufactured by Japan Epoxy Resins).

Examples of the cationically polymerizable compound having an oxetane group include 3-ethyl-3-hydroxymethyloxetane (OXT-101), 1,4-bis-3-ethyloxetane Cyclobutan-3-ylmethoxymethylbenzene (OXT-121), bis-1-ethyl-3-oxetanyl methyl ether (OXT-221), 3-ethyl-3-2 -Ethylhexyloxymethyloxetane (OXT-212), 3-ethyl-3-phenoxymethyloxetane (OXT-211) (above, the trade names in brackets and manufactured by Toagosei), or trade names Etanacol EHO, Etanacol OXBP, Etanacol OXTP, Etanacol OXMA (the above are trade names, manufactured by Ube Industries).

(3) Polymerization initiator

The polymer of at least one of the radically polymerizable compound and the cationically polymerizable compound contained in the resin-containing layer used in the present invention can be obtained, for example, by polymerizing the radically polymerizable compound and the cationic polymerizable compound described above. A polymerization initiator may be added to at least one of the synthetic compounds as needed, and a polymerization reaction is carried out by a known method.

As the above-mentioned polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and a cationic polymerization initiator, etc. can be appropriately selected and used. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations to perform radical polymerization and cationic polymerization.

衍生物等，更具體而言，可列舉：1,3-二(三級丁基二氧基羰基)二苯甲酮、3,3',4,4'-四(三級丁基二氧基羰基)二苯甲酮、3-苯基-5-異

唑啉酮、2-巰基苯并咪唑、雙(2,4,5-三苯基)咪唑、2,2-二 甲氧基-1,2-二苯基乙烷-酮(商品名Irgacure651，Ciba Japan股份有限公司製造)、1-羥基-環己基-苯基-酮(商品名Irgacure184，Ciba Japan股份有限公司製造)、2-苄基-2-二甲胺基-1-(4-(N-

啉基)苯基)-丁烷-1-酮(商品名Irgacure369，Ciba Japan股份有限公司製造)、雙(η5-2,4-環戊二烯-1-基)-雙(2,6-二氟-3-(1H-吡咯-1-基)-苯基)鈦)(商品名Irgacure784、Ciba Japan股份有限公司製造)等，但並不限定於該等。 The radical polymerization initiator should just be capable of releasing a substance that initiates radical polymerization by at least one of light irradiation and heating. For example, as photoradical polymerization initiators, imidazole derivatives, biimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, and aluminate complexes can be mentioned. , organic peroxides, N-alkoxypyridinium salts, 9-oxysulfur

Derivatives and the like, more specifically, 1,3-bis(tertiary butyldioxycarbonyl)benzophenone, 3,3',4,4'-tetrakis(tertiary butyldioxycarbonyl) carbonyl) benzophenone, 3-phenyl-5-iso

oxazolinone, 2-mercaptobenzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethan-one (trade name Irgacure651, Manufactured by Ciba Japan Co., Ltd.), 1-hydroxy-cyclohexyl-phenyl-one (trade name Irgacure184, manufactured by Ciba Japan Co., Ltd.), 2-benzyl-2-dimethylamino-1-(4-( N-

Lino)phenyl)-butan-1-one (trade name Irgacure369, manufactured by Ciba Japan Co., Ltd.), bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6- Difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium) (trade name Irgacure784, manufactured by Ciba Japan Co., Ltd.) etc., but not limited to these.

In addition to the above, commercially available products may also be used, and specific examples include Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, Irgacure 1870, Irgacure OXE01, DAROCUR TPO, DAROCUR, manufactured by Ciba Japan Co., Ltd. 1173. Speedcure MBB, Speedcure PBZ, Speedcure ITX, Speedcure CTX, Speedcure EDB, Esacure ONE, Esacure KIP150, Esacure KTO46 manufactured by Nihon SiberHegner Co., Ltd., KAYACURE DETX-S, KAYACURE CTX, KAYACURE manufactured by Nihon Kayaku Co., Ltd. BMS, KAYACURE DMBI, etc.

Moreover, the cationic polymerization initiator should just be able to release the substance which starts cationic polymerization by at least any one of light irradiation and heating. Examples of the cationic polymerization initiator include: sulfonic acid ester, imidate sulfonic acid ester, dialkyl-4-hydroxy perionate, arylsulfonic acid-p-nitrobenzyl ester, silanol-aluminum complex, (η ⁶ -benzene)(η ⁵ -cyclopentadienyl) iron (II), etc., more specifically, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N -Tosyl phthalimide, etc., but not limited to these.

化合物、芳茂鐵(iron arene)錯合物等，更具體而言，可列舉：二苯基錪、二甲苯基錪、雙(對三級丁基苯基)錪、雙(對氯苯基)錪等錪之氯化物、溴化物、氟硼酸鹽、六氟磷酸鹽、六氟銻酸鹽等錪鹽；三苯基鋶、4-三級丁基三苯基鋶、三(4-甲基苯基)鋶等鋶之氯化物、溴化物、氟硼酸鹽、六氟磷酸鹽、六氟銻酸鹽等鋶鹽；2,4,6-三(三氯甲基)-1,3,5-三

、2-苯基-4,6-雙(三氯甲基)-1,3,5-三

、2-甲基-4,6-雙(三氯甲基)-1,3,5-三

等2,4,6-取代-1,3,5三

化合物等，但並不限定於該等。 As a radical polymerization initiator and a cationic polymerization initiator, aromatic iodonium salts, aromatic periconium salts, aromatic diazonium salts, aromatic phosphonium salts, triazonium salts,

Compounds, iron arene complexes, etc., more specifically, diphenyl iodonium, xylyl iodonium, bis(p-tertiary butylphenyl) iodonium, bis(p-chlorophenyl) ) iodonium salts such as iodonium chloride, bromide, fluoroborate, hexafluorophosphate, hexafluoroantimonate and other iodonium salts; 2,4,6-Tris(trichloromethyl)-1,3, 2,4,6-tris(trichloromethyl)-1,3, 5-Three

, 2-phenyl-4,6-bis(trichloromethyl)-1,3,5-tri

, 2-methyl-4,6-bis(trichloromethyl)-1,3,5-tri

etc. 2,4,6-substituted-1,3,5-tri

compounds, etc., but are not limited to these.

(4) Additives

The resin-containing layer used in the present invention may also contain additives such as antistatic agents, antiglare agents, antifouling agents, inorganic or organic fine particles for improving hardness, leveling agents, various sensitizers, etc. .

As the particles for increasing the hardness, inorganic fine particles such as silicon oxide particles are suitably used, and when silicon oxide particles are used, it is preferable to improve the adhesion between the polyimide film and the resin-containing layer.

3. The composition of the laminate

In the laminate system of the present invention, the polyimide film and the resin-containing layer are located adjacent to each other, and the polyimide film is preferably the polyimide film and the resin-containing layer in terms of adhesion between the polyimide film and the resin-containing layer. The surface of the imide film having a relatively large concentration of silicon atoms is formed by being in close contact with the resin-containing layer.

In addition to the above-mentioned polyimide film and the above-mentioned resin-containing layer, the layered product of the present invention may be further layered with a gel containing urethane, acrylic resin, etc., as long as the effect of the present invention is not impaired. The layer may have a multilayer structure in which the resin-containing layer has two or more layers. In addition, in the laminate of the present invention, the above-mentioned resin-containing layer or the above-mentioned other layers may be laminated on the surface side of the polyimide film whose silicon atom concentration is relatively small.

The overall thickness of the layered product of the present invention may be appropriately selected according to the application, and in terms of strength, it is preferably 10 μm or more, and more preferably 40 μm or more. On the other hand, in terms of bending resistance, it is preferably 300 μm or less, and more preferably 250 μm or less.

Moreover, in the layered product of the present invention, the thickness of each resin-containing layer may be appropriately selected according to the application, and is preferably 2 μm or more and 80 μm or less, and more preferably 3 μm or more and 50 μm or less. Moreover, from the viewpoint of preventing curling, a resin-containing layer may be formed on both surfaces of the polyimide film.

4. Characteristics of laminated body

The pencil hardness of the resin-containing layer side surface of the layered product of the present invention is preferably H or more, more preferably 2H or more, and still more preferably 3H or more. Furthermore, in the case of a laminate having resin-containing layers on both surfaces, it is preferable that at least one surface has the aforementioned pencil hardness.

The pencil hardness of the laminate of the present invention can be measured in the same manner as the pencil hardness of the polyimide film described above.

The total light transmittance of the laminate of the present invention measured in accordance with JIS K7361-1 is preferably 85% or more, more preferably 88% or more, and more preferably 90% or more. Since the transmittance is so high, it has good transparency and can be used as a substitute for glass.

The above-mentioned total light transmittance of the laminate of the present invention can be measured in the same manner as the total light transmittance measured in accordance with JIS K7361-1 of the above-mentioned polyimide film.

The yellowness (YI value) of the layered product of the present invention calculated based on JIS K7373-2006 is preferably 30 or less, more preferably 20 or less, more preferably 15 or less, particularly preferably 10 or less.

The yellowness (YI value) of the laminate of the present invention can be measured in the same manner as the yellowness (YI value) of the polyimide film calculated based on JIS K7373-2006.

The haze value of the layered product of the present invention is preferably 10 or less, more preferably 8 or less, more preferably 5 or less in terms of light transmittance.

The haze value of the laminate of the present invention can be measured in the same manner as the haze value of the polyimide film described above.

The birefringence in the thickness direction of the laminate of the present invention at a wavelength of 590 nm is preferably 0.020 or less, more preferably 0.015 or less, more preferably 0.010 or less, and more preferably less than 0.008.

The above-mentioned birefringence of the laminate of the present invention can be measured in the same manner as the birefringence in the thickness direction of the above-mentioned polyimide film at a wavelength of 590 nm.

5. Use of laminates

The use of the laminate of the present invention is not particularly limited, and for example, it can be used for the same use as the use of the polyimide film of the present invention described above.

6. Manufacturing method of laminated body

As a production method of the layered product of the present invention, for example, a production method comprising the steps of forming a radically polymerizable compound and a cationically polymerizable compound on the surface of the polyimide film of the present invention where the silicon atom concentration is relatively large is formed. A coating film of the composition for forming a layer containing at least one resin of the compound; and curing the above coating film.

The said composition for resin containing layer formation contains at least 1 type of a radically polymerizable compound and a cationically polymerizable compound, and may further contain a polymerization initiator, a solvent, an additive, etc. as needed.

Here, the radically polymerizable compounds, cationically polymerizable compounds, polymerization initiators, and additives contained in the composition for forming the resin-containing layer may be the same as those described in the above-mentioned resin-containing layer, and the solvent may be freely disclosed. A known solvent is appropriately selected and used.

As a method of forming the coating film of the composition for forming the resin-containing layer on the surface of the polyimide film having a relatively large concentration of silicon atoms, for example, the surface of the polyimide film having a relatively large concentration of silicon atoms can be exemplified. The method of applying the composition for forming the resin-containing layer described above by a known application means.

The above-mentioned coating means is not particularly limited as long as it is a method capable of coating with a target film thickness, and examples thereof include the same means as those for coating the above-mentioned polyimide precursor resin composition on the support.

The solvent is removed by drying the coating film of the composition for forming a resin-containing layer as necessary. Examples of the drying method include drying under reduced pressure, drying under heating, and a method of combining these dryings. Moreover, when drying under normal pressure, it is preferable to perform drying at 30 degreeC or more and 110 degrees C or less.

The coating film obtained by applying the above-mentioned composition for forming a resin-containing layer and drying it as necessary may be subjected to light irradiation and a cationic polymerizable compound according to the polymerizable groups of the radically polymerizable compound and the cationically polymerizable compound contained in the composition. At least any one of heating hardens the coating film, thereby forming a polymer containing at least one of a radically polymerizable compound and a cationically polymerizable compound on the surface of the polyimide film where the silicon atom concentration is relatively large. The resin contains Floor.

As the light irradiation, ultraviolet rays, visible light, electron beams, ionizing radiation, and the like are mainly used. In the case of ultraviolet curing, ultraviolet rays emitted from ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arcs, xenon arcs, metal halide lamps, etc. are used. The irradiation dose of the energy ray source is about 50~5000mJ/cm ² in terms of the cumulative exposure dose when the ultraviolet wavelength is 365nm.

In the case of heating, the treatment is usually performed at a temperature of 40°C or higher and 120°C or lower. In addition, the reaction can also be carried out by standing at room temperature (25° C.) for 24 hours or more.

III. Surface Materials for Displays

The surface material for a display of the present invention is the polyimide film of the present invention or the laminate of the present invention.

The surface material for displays of this invention is arrange|positioned and used so that it may be located on the surface of various displays. Like the polyimide film of the present invention and the laminate of the present invention, the surface material for a display of the present invention can improve bending resistance and has surface hardness sufficient as a protective film, so it can be used particularly suitably as a flexible display use. Furthermore, the surface material for a display of the present invention has sufficient transparency as a transparent film like the above-mentioned polyimide film of the present invention and the laminate of the present invention, and can reduce optical strain, so that the display quality of the display can be suppressed. reduce.

The surface material for a display of the present invention can be used for various known displays without particular limitation. For example, it can be used for the displays described in the application of the polyimide film of the present invention.

Furthermore, when the surface material for a display of the present invention is the above-mentioned laminate of the present invention, the outermost surface after being disposed on the surface of the display may be the surface on the side of the polyimide film, or may be a resin containing On the surface on the layer side, when a hard coat layer is used as the resin-containing layer, it is preferable to arrange the surface material for a display of the present invention so that the surface on the side of the hard coat layer becomes the surface. Moreover, the surface material for displays of this invention may have an anti-fingerprint adhesion layer on the outermost surface.

Moreover, it does not specifically limit as a method to arrange|position the surface material for displays of this invention on the surface of a display, For example, the method of passing through an adhesive layer, etc. are mentioned. As said adhesive layer, the conventionally well-known adhesive layer which can be used for the adhesiveness of the surface material for displays can be used.

Example

[Evaluation method]

Hereinafter, among the surfaces of the polyimide film, the surface contacting the support in the drying step may be referred to as a casting surface, and the surface opposite to the casting surface may be referred to as an environmental surface.

<Weight Average Molecular Weight of Polyimide Precursor>

The weight-average molecular weight of the polyimide precursor is obtained by preparing the polyimide precursor into a N-methylpyrrolidone (NMP) solution with a concentration of 0.5% by weight, and using 10mmol% LiBr-NMP with a water content of 500ppm or less The solution was measured as a developing solvent using a GPC apparatus (HLC-8120 manufactured by Tosoh, using a column: GPC LF-804 manufactured by SHODEX) under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL/min, and 40°C. The weight average molecular weight of the polyimide precursor was determined based on a polystyrene standard sample having the same concentration as the sample.

<Viscosity of polyimide precursor solution>

The viscosity of the polyimide precursor solution was measured using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.) at 25° C. with a sample amount of 0.8 ml.

<weight average molecular weight of polyimide>

The weight-average molecular weight of polyimide is obtained by preparing polyimide as a N-methylpyrrolidone (NMP) solution with a concentration of 0.2 wt%, and using a 30 mmol% LiBr-NMP solution with a water content of 500 ppm or less as a developing solvent , using a GPC device (Tosoh, HLC-8120, using a column: GPC LF-804 manufactured by SHODEX), the sample injection volume was 50 μL, the solvent flow rate was 0.4 mL/min, and the measurement was performed at 40°C. The weight-average molecular weight of polyimide was determined on the basis of a polystyrene standard sample having the same concentration as the sample.

<Viscosity of Polyimide Solution>

The viscosity of the polyimide solution was measured using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.) at 25° C. with a sample amount of 0.8 ml.

<Silicon atom content ratio (mass %) of polyimide>

The silicon atom content ratio (mass %) of polyimide is calculated from the added molecular weight.

For example, 1 mole of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) as the acid dianhydride component is used as the diamine component in the polyimide of Example 8. 2,2'-bis(trifluoromethyl)benzidine (TFMB) 0.9 mol and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) 0.1 mol can be calculated as follows.

Regarding the molecular weight of 1 mole of polyimide repeating unit, from 6FDA: (C) 12.01×19+(F)19.00×6+(O)16.00×4+(H)1.01×6=412.25

From TFMB: {(C)12.01×14+(F)19.00×6+(N)14.01×2+(H)1.01×6}×0.9=284.60

From AprTMOS: {(C)12.01×10+(O)16.00×1+(N)14.01×2+(Si)28.09×2+(H)1.01×24}×0.1=24.45, which is 412.25+ 284.60+24.45=721.30.

The silicon atom content ratio (mass %) in 1 mole of the polyimide repeating unit was calculated as (28.09×2×0.1)/721.30×100=0.8 (mass %).

Furthermore, for the two-terminal amine-modified diphenyl polysiloxane oil of Comparative Example 2 (manufactured by Shin-Etsu Chemical Co., Ltd.: X22-1660B-3, side-chain phenyl type, number average molecular weight 4400), if it is assumed that the amine group passes through - (CH ₂ ) ₃ - is bound to polysiloxane, the number of repeating units of diphenylsiloxane is calculated to be 19.7 on average from the number average molecular weight of 4400, and it is calculated that 1 molecule contains an average of 21.7 silicon atoms.

<Total light transmittance>

According to JIS K7361-1, the measurement was performed with a haze meter (HM150 manufactured by Murakami Color Technology Laboratory).

Also, for example, the total light transmittance when the thickness is 100 μm can be converted by the Lambert-Beer law.

Specifically, according to the Lambert-Beer law, the transmittance T is given by Log ₁₀ (1/T)=kcb

(k=constant inherent in matter, c=concentration, b=optical path length).

In the case of the transmittance of the film, if it is assumed that the density is constant even if the film thickness changes, c is also a constant, so the above formula can be expressed as Log ₁₀ (1/T)=fb using the constant f

(f=kc). Here, if the transmittance at a certain film thickness is known, the intrinsic constant f of each substance can be obtained. Therefore, if using T=1/10 ^f. By substituting the intrinsic constant into f, and substituting the target film thickness into ^b , the transmittance at the required film thickness can be obtained.

<YI value (yellowness)>

The YI value is calculated based on the transmittance measured by the spectrophotometric method specified in JIS Z8720 using an ultraviolet-visible-near-infrared spectrophotometer (Nippon Shoko Co., Ltd., V-7100) in accordance with JIS K7373-2006 .

Also, for example, regarding the YI value when the thickness is 100 μm, the transmittance at each wavelength obtained by measuring the sample with a certain film thickness at intervals of 5 nm between 380 nm and 780 nm can be compared with the above-mentioned total light transmittance. Similarly, the conversion value of each transmittance at each wavelength with different thicknesses was obtained by Lambert-Beer's law, and the YI value was calculated and used based on the conversion value.

<Haze value>

According to JIS K-7105, the measurement was performed with a haze meter (HM150 manufactured by Murakami Color Institute).

<Birefringence>

The retardation value (Rth) in the thickness direction of the polyimide film was measured using a retardation measuring device (manufactured by Oji Scientific Instruments Co., Ltd., product name "KOBRA-WR") with light at 25° C. and a wavelength of 590 nm. The thickness direction retardation value (Rth) measures the retardation value of 0-degree incidence and the retardation value of 40-degree oblique incidence, and calculates the thickness direction retardation value Rth from these retardation values. The retardation value of the above-mentioned 40-degree oblique incidence was measured by making light having a wavelength of 590 nm incident on the retardation film from a direction inclined by 40 degrees with respect to the normal line of the retardation film.

The birefringence of the polyimide film was substituted into the formula: Rth/d (film thickness (nm) of the polyimide film) to obtain.

<Glass transition temperature>

Using a dynamic viscoelasticity measuring device RSA III (TA Instruments Japan Co., Ltd.), the measurement range was set to -150°C to 400°C, the frequency was 1 Hz, the heating rate was 5°C/min, the sample width was set to 5 mm, and the gap between the chucks was set to 5 mm. The dynamic viscoelasticity was measured with a distance of 20 mm, and the glass transition temperature (Tg) was determined from the peak temperature of tan δ (tan δ = loss elastic modulus (E")/storage elastic modulus (E')).

<tensile elastic modulus>

The test piece cut into a polyimide film of 15mm×40mm was adjusted for 2 hours at a temperature of 25°C and a relative humidity of 60%, and the tensile speed was set to 10mm/min according to JIS K7127, and the gap between the chucks was adjusted for 2 hours. The distance was set to 20 mm and the tensile modulus of elasticity at 25°C was measured. A tensile tester was used (Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN).

<Static bending test>

Hereinafter, the method of the static bending test will be described with reference to FIG. 1 .

Bend the test piece 1 cut into a polyimide film of 15mm×40mm at the position of half of the long side, and clamp the metal sheet 2 (100mm thick) with the thickness of 6mm from the top and bottom of the two ends of the long side of the test piece 1. × 30 mm × 6 mm) were arranged, and the two ends of the test piece 1 and the upper and lower surfaces of the metal sheet 2 overlapped with each other by 10 mm, and were fixed with adhesive tapes. The metal sheet 2 to which the test piece 1 is fixed is clamped by glass plates (100 mm×100 mm×0.7 mm) 3a and 3b from the top and bottom, and the test piece 1 is fixed in a state of bending with an inner diameter of 6 mm. At this time, dummy test pieces 4 a and 4 b are sandwiched between the parts of the metal sheet 2 where the test piece 1 does not exist, and the glass plates 3 a and 3 b are fixed with tape so that the glass plates 3 a and 3 b are parallel.

After the test piece fixed in a bent state in this way is allowed to stand for 24 hours in an environment of 60±2°C and 93±2% relative humidity (RH), remove the glass plate and the tape for fixing the test piece, and release the application. To the power of the test piece. Thereafter, one end of the test piece was fixed, and 30 minutes after the force applied to the test piece was released, the inner angle of the test piece was measured.

Furthermore, when the film is completely restored without being affected by the static bending test, the above-mentioned inner angle is 180°.

<Dynamic bending test>

Use tape to fix the test piece cut into a size of 20mm×100mm in a constant temperature and humidity test system (DMX-FS, a U-shaped extension test fixture made by YUASA SYSTEM). After setting the test piece in the same folded state as in the static bending test described above, that is, the distance between the two ends of the long side of the test piece in the folded state becomes 6 mm, the test piece was heated at 60±2°C and 93±2% relative humidity (RH). ), or 200,000 times of repeated bending at 25℃±2℃ and 50±10% relative humidity (RH) with 90 times of bending in 1 minute.

Then, 30 minutes after the test piece was taken out, one end of the obtained test piece was fixed, and the inner angle of the test piece was measured.

Furthermore, when the film is completely restored without being affected by the dynamic bending test, the above-mentioned inner angle is 180°.

<Pencil Hardness>

It is carried out by the following method: After the measurement sample is subjected to humidity adjustment at a temperature of 25°C and a relative humidity of 60% for 2 hours, a test pencil specified in JIS-S-6006 is used, and a test pencil manufactured by Toyo Seiki Co., Ltd. is used. Pencil scratch coating film hardness tester performs the pencil hardness test (0.98N load) specified by JIS K5600-5-4 (1999) on the environmental surface of the film, and evaluates the highest pencil hardness without damage.

<Evaluation of Peelability>

The polyimide film was visually observed, and the peelability from the support at the time of production was evaluated according to the following evaluation criteria.

A: Since the peelability from the support was good, no wrinkles, cracks, streaks, or breaks were generated on the film.

B: A few streaks and wrinkles were generated on the film due to peeling from the support, but the film was practically usable.

C: Defective peeling. There are obvious stripes and wrinkles on the membrane, which is the degree of partial rupture of the membrane.

In addition, a stripe means the pattern which arises in the transversal direction (TD direction) by the peeling stress which spreads the film unevenly. The wrinkle refers to a wrinkle generated in the longitudinal direction when the film is stretched and then shrunk when peeled from the support.

<Atomic concentration measurement>

Under the following measurement conditions, each atomic concentration of the environmental surface and the casting surface of the polyimide film was measured by X-ray photoelectron spectroscopy (XPS). The average value of n=2 is shown in Table 2. Furthermore, the measured value to the second decimal place is displayed in parentheses together with the value rounded to the first decimal place according to JIS Z8401:1999.

˙ Device used: Theta-Probe (XPS device manufactured by Thermo Scientific)

˙ Incident X-ray: monochromatic Al Ka line (monochromatic X-ray, hν=1486.6eV)

˙X-ray irradiation area (measurement area): 400μm

˙X-ray output: 100W (15kV˙6.7mA)

˙Photoelectron swept-in angle: 53° (wherein, the sample normal is set to 0°)

˙Static neutralization conditions: electron neutralization gun (+6V, 0.05mA), low acceleration Ar ⁺ ion irradiation

˙Measuring peaks: Si2p, Cls, Nls, Ols, Fls

˙Quantitative: The background value is obtained by Shirley method, and the atomic ratio is calculated from the obtained peak area by the relative sensitivity coefficient method.

(Synthesis Example 1)

In a 500ml separable flask, 302.0g of dehydrated dimethylacetamide and 3.735g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) ( 15mmol) dissolved in the solution was controlled to a liquid temperature of 30°C, and then slowly added 2.22g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) so that the temperature rose by 2°C or less (5 mmol) and stirred with a mechanical stirrer for 4 hours. To this, 27.2 g (85 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added, and after confirming complete dissolution, 4,4'- (Hexafluoroisopropylidene)diphthalic anhydride (6FDA) 42.0 g (94.5 mmol) to synthesize a polyimide precursor solution 1 in which the polyimide precursor 1 was dissolved (solid content: 20 wt. %). The molar ratio of TFMB and AprTMOS used in the polyimide precursor 1 was 85:15. The viscosity of the polyimide precursor solution 1 (solid content 20% by weight) at 25° C. was 17770 cps, and the weight average molecular weight of the polyimide precursor 1 measured by GPC was 117,000.

(Synthesis Examples 2 to 8)

According to the procedure of the above-mentioned synthesis example 1, the reaction was carried out so as to obtain the raw material and solid content concentration described in Table 1, and the polyimide precursor solutions 2 to 8 were prepared.

(Comparative Synthesis Example 1)

In a 500ml separable flask, 345.3g of dehydrated dimethylacetamide and 49.7g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) ( 200 mmol) dissolved in the solution was controlled to have a liquid temperature of 30°C, and then 88.4 g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was slowly added so that the temperature rose by 2°C or less. (199 mmol) to synthesize the comparative polyimide precursor solution 1 (solid content 40% by weight) in which the comparative polyimide precursor 1 was dissolved. The viscosity of the comparative polyimide precursor solution 1 (solid content 40% by weight) at 25° C. was 3900 cps, and the weight average molecular weight of the comparative polyimide precursor 1 measured by GPC was 42,000.

(Comparative Synthesis Example 2)

Two-terminal amine-modified dimethylphenyl polysiloxane oil (manufactured by Shin-Etsu Chemical Co., Ltd.: X22-1660B-3 (number average molecular weight 4400) was added to a 3L separable flask equipped with an oil bath with a stirring bar while introducing nitrogen gas. ) 12.25g, N-methyl-2-pyrrolidone (NMP) 3432g, then 6FDA222.12g (0.5 mol) was added, and it stirred at room temperature for 30 minutes. Then, 152.99 g (0.478 mol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added to confirm the dissolution, and then the mixture was stirred at room temperature for 3 hours, then heated to 80° C. and stirred for 4 hours. , then the oil bath was removed and returned to room temperature to obtain a comparative polyimide precursor solution 2 (solid content 10% by weight). The viscosity of the comparative polyimide precursor solution 2 (solid content 10% by weight) at 25°C was 89 cps, and the weight average molecular weight of the comparative polyimide precursor 2 measured by GPC was 66900.

(Synthesis Example 9 (chemical imidization))

In a 500 mL separable flask, dehydrated dimethylacetamide (367.1 g), and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) ( 2.33 g, 9.4 mmol) was dissolved in the solution after the liquid temperature was controlled to 30°C, and then slowly poured into 4,4'-(hexafluoroisopropylidene) diphthalic anhydride ( 6FDA) (2.08 g, 4.7 mmol) and stirred with a mechanical stirrer for 1 hour. 2,2'-bis(trifluoromethyl)benzidine (TFMB) (57.07 g, 178.2 mmol) was added to this, and after confirming complete dissolution, 4,4 was gradually added in several portions so that the temperature rose by 2°C or less. '-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) (80.83 g, 182.0 mmol), thereby synthesizing a polyimide precursor solution 1' in which the polyimide precursor 1' was dissolved ( Solid content 28% by weight).

The above solution was lowered to room temperature, dehydrated dimethylacetamide (202.2 g) was added and stirred until homogeneous. Next, pyridine (59.05 g, 0.747 mmol) and acetic anhydride (76.22 g, 0.747 mol) were added as catalysts, and the mixture was stirred at room temperature for 24 hours to synthesize a polyimide solution. A portion (692.2 g) of the obtained polyimide solution was transferred to a 5 L separable flask, and butyl acetate (471.1 g) was added and stirred until uniform. Next, methanol (1046 g) was slowly added to obtain a slightly cloudy solution. To the slightly cloudy solution, methanol (2443 kg) was added in one go to obtain a white slurry. The above slurry was filtered and washed with methanol five times to obtain polyimide 1 (104.7 g). The weight average molecular weight of polyimide 1 measured by GPC was 180,000.

Polyimide 1 was dissolved in a mixed solvent of butyl acetate and PGMEA (8:2, volume ratio) to prepare polyimide solution 1 with a solid content of 25% by mass. The viscosity of the polyimide solution 1 (solid content: 25% by weight) at 25°C was 58500 cps.

Hereinafter, the abbreviations in the table are as follows.

TFMB: 2,2'-bis(trifluoromethyl)benzidine

AprTMOS: 1,3-bis(3-aminopropyl)tetramethyldisiloxane

6FDA: 4,4'-(hexafluoroisopropylidene) diphthalic anhydride

[Production of Polyimide Film]

(Examples 1 to 8, Comparative Examples 1 to 2)

By using the polyimide precursor solutions 1 to 8 and the comparative polyimide precursor solutions 1 to 2 to carry out the procedures of the following (1) to (4), respectively, polyimide with the thickness shown in Table 2 was produced. Amine film.

(1) Each polyimide precursor solution was coated on a steel support, dried at 40° C. for 60 minutes in a circulating oven, and then dried at 100° C. for 30 minutes to form a coating film.

(2) Peeling the coating film from the support (peeling strength 0.1 N/25 mm, peeling speed 200 mm/min, peeling angle 180°).

(3) After peeling, the outer periphery of the coating film is fixed to a frame-shaped metal jig.

(4) Under nitrogen flow (oxygen concentration below 100 ppm), the temperature was raised to 350°C at a heating rate of 10°C/min and kept at 350°C for 1 hour, then cooled to room temperature and removed from the frame-shaped metal jig to obtain Each polyimide film.

(Example 9)

A polyimide film having the thickness shown in Table 2 was produced by carrying out the following procedures (1) to (4) using the polyimide solution 1 obtained in Synthesis Example 9.

(1) The polyimide solution 1 was coated on a steel support, dried at 40° C. for 60 minutes in a circulating oven, and then dried at 100° C. for 30 minutes to form a coating film.

(2) Peeling the coating film from the support (peeling strength 0.1 N/25 mm, peeling speed 200 mm/min, peeling angle 180°).

(3) After peeling, the outer periphery of the coating film is fixed to a frame-shaped metal jig.

(4) Under nitrogen flow (oxygen concentration below 100 ppm), the temperature was raised to 250°C at a heating rate of 10°C/min and kept at 250°C for 1 hour, then cooled to room temperature and removed from the frame-shaped metal jig to obtain Polyimide film.

Each of the obtained polyimide films was evaluated using the above evaluation method. The evaluation results are shown in Table 2.

[Production of laminated body]

1-hydroxy-cyclohexyl-phenyl-ketone ( manufactured by BASF, Irgacure 184), and a resin composition for forming a resin-containing layer was prepared.

The polyimide film obtained above was cut into 10 cm × 10 cm, and the resin composition for forming the resin-containing layer was coated on the environmental surface, and was irradiated with ultraviolet rays at an exposure amount of 200 mJ/cm ² under nitrogen flow to harden it. The resin containing layer of the cured film with a film thickness of 10 micrometers was formed, and the laminated body was produced.

<Evaluation of Adhesion>

Regarding the adhesion of the resin-containing layers of the obtained laminates, a cross-cut test in accordance with JIS K5600-5-6 was performed, and the peeling operation with the tape was repeated 5 times. The evaluation was performed according to the following evaluation criteria. The evaluation results are shown in Table 2.

A: Peeling of the resin-containing layer did not occur even after the peeling operation with the tape was repeated 5 times.

B: No peeling of the resin-containing layer occurred after the peeling operation with the tape was performed once, but peeling of the resin-containing layer occurred when the peeling operation with the tape was repeated five times.

C: After the peeling operation with the tape was carried out once, the resin-containing layer was completely peeled off along the cut edge.

<Pencil Hardness>

About the resin containing layer side surface of each obtained laminated body, the pencil hardness evaluation was performed by the same method as the polyimide film. The evaluation results are shown in Table 2.

According to Table 2, the polyimide films of Examples 1 to 9, which are equivalent to the polyimide films of the present invention, contain silicon atoms on both the environmental surface and the casting surface, but the concentration of silicon atoms on the environmental surface is higher, and the environmental surface The silicon atom concentration is 10.0 atomic % or less, and the tensile modulus of elasticity is 1.8 GPa or more, thereby improving the adhesion of the resin-containing layer to the environment, and the peelability of the casting surface from the support is good. The resulting defects are suppressed. Moreover, the polyimide films of Examples 1 to 9 showed that the decrease in transparency and the decrease in surface hardness were suppressed, and the bending resistance was improved. Moreover, in Examples 1-9, the laminated body which improved the adhesiveness of a polyimide film and a resin containing layer was obtained.

Moreover, the pencil hardness of the laminated bodies of Examples 1-5 was high compared with the laminated bodies of Examples 6-9. It is presumed that the reason for this is that the concentration of silicon atoms on the surface of the polyimide film is moderately higher in the laminates of Examples 1 to 5 compared with the laminates of Examples 6 to 9, and the adhesion between the polyimide film and the hard coat layer is high. Excellent sex.

The polyimide film of Comparative Example 1 had a defect due to peeling from the support. The reason for this is presumed to be that the polyimide contains a large amount of silicon atoms, the Si concentration on the front and back of the film is substantially the same, the Si concentration on the casting surface is too large, and the strength of the coating film when the support is peeled off is insufficient. In addition, the tensile modulus of elasticity of the polyimide film of Comparative Example 1 did not reach 1.8 GPa, the result of the static bending test was 0 degrees, the film was still in the bending state of the static bending test and did not recover at all, and the bending resistance was poor. Pencil hardness is extremely poor.

The polyimide film of Comparative Example 2 had a defect caused by peeling from the support. The reason for this is presumed that the strength of the coating film was insufficient when the support was peeled off. The tensile modulus of elasticity of the polyimide film of Comparative Example 2 did not reach 1.8 GPa, the static bending resistance was poor, and the pencil hardness was extremely poor. Moreover, the adhesiveness of the polyimide film and the resin containing layer of the laminated body of the comparative example 2 was inferior. The reason for this is considered to be that in Comparative Example 2, the concentration of silicon atoms on the environmental surface exceeded 10 atomic %, so that the surface of the polyimide film was excessively dissolved by the solvent in the composition for forming a resin-containing layer, and thus the polyimide film was dissolved in the polyimide film. The interface between the imine film and the resin-containing layer produces a fragile portion.

Claims (17)

A polyimide film comprising a polyimide having a structure represented by the following general formula (1-1), the total light transmittance measured according to JIS K7361-1 is 85% or more, according to JIS K7373-2006 The calculated yellowness was 30 or less, and the tensile modulus at 25°C was 1.8 when measured on a 15mm×40mm test piece according to JIS K7127 with a tensile speed of 10mm/min and a distance between chucks of 20mm. Above GPa, silicon atoms are contained on one side and the other side, but the silicon atom concentration on one side is different from that on the other side.

(In general formula (1-1), R ^1' represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ^2' represents a divalent group of a diamine residue, R 2.5 mol % or more and 50 mol % or less of the total amount of ^2' are diamine residues having silicon atoms in the main chain, and 50 mol % or more and 97.5 mol % are those which do not have silicon atoms and are aromatic Diamine residue of ring or aliphatic ring, n' represents the number of repeating units). The polyimide film of claim 1, wherein, in the polyimide having the structure represented by the general formula (1-1), R ^1' in the general formula (1-1) is Selected from cyclohexanetetracarboxylic dianhydride residue, cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride residue, cyclobutane Tetracarboxylic dianhydride residues, pyromic acid dianhydride residues, 3,3',4,4'-biphenyltetracarboxylic dianhydride residues, 2,2',3,3'-biphenyltetrakis Carboxylic dianhydride residues, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residues, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residues , 3,3'-(hexafluoroisopropylidene)diphthalic anhydride residue, 4,4'-oxydiphthalic anhydride residue, and 3,4'-oxydiphthalic anhydride At least one tetravalent group in the group consisting of acid anhydride residues. The polyimide film of claim 1 or 2 of the claimed scope, wherein, in the polyimide having the structure represented by the general formula (1-1), R ² in the general formula (1-1) The diamine residue with aromatic ring or aliphatic ring in ^' is selected from the group consisting of trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4'-diaminodiphenyl residue, 3,4'-diaminodiphenyl residue, 2,2-bis(4-aminophenyl)propane residue, 2,2 -bis(4-aminophenyl)hexafluoropropane residue, and at least one divalent group in the group consisting of a divalent group represented by the following general formula (2),

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or a perfluoroalkyl group). A polyimide film comprising a polyimide having a structure represented by the following general formula (1), the total light transmittance measured according to JIS K7361-1 is 85% or more, calculated according to JIS K7373-2006 The yellowness is 30 or less, and the tensile modulus of elasticity at 25°C is 1.8 GPa or more when measured on a test piece of 15 mm × 40 mm with a tensile speed of 10 mm/min and a distance between chucks of 20 mm in accordance with JIS K7127. , contains silicon atoms on one side and the other side, but the concentration of silicon atoms on one side is different from the concentration of silicon atoms on the other side, and the concentration of silicon atoms on at least one side is 1.0 atomic % or more,

(In general formula (1), R ¹ represents a tetravalent group of a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, R ² represents a divalent group of a diamine residue, and the total amount of R ² 10 mol% or more and 50 mol% or less are diamine residues with 1 or 2 silicon atoms in the main chain, 50 mol% or more and 90 mol% or less are no silicon atoms and aromatic Diamine residue of ring or aliphatic ring, n represents the number of repeating units). The polyimide film of claim 4, wherein, in the polyimide having the structure represented by the general formula (1), R ¹ in the general formula (1) is selected from cyclohexane Tetracarboxylic dianhydride residue, cyclopentane tetracarboxylic dianhydride residue, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride residue, cyclobutane tetracarboxylic dianhydride Residues, Pyromic acid dianhydride residues, 3,3',4,4'-biphenyltetracarboxylic dianhydride residues, 2,2',3,3'-biphenyltetracarboxylic dianhydride residues base, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3' -(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4'-oxydiphthalic anhydride residue, and 3,4'-oxydiphthalic anhydride residue at least one tetravalent group in the group. The polyimide film of claim 4 or 5 of the scope of the application, wherein, in the polyimide having the structure represented by the general formula (1), the R ² in the general formula (1) has the The diamine residue of aromatic ring or aliphatic ring is selected from the group consisting of trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4'- Diaminodiphenyl residue, 3,4'-diaminodiphenyl residue, 2,2-bis(4-aminophenyl)propane residue, 2,2-bis(4- aminophenyl) hexafluoropropane residue, and at least one divalent group in the group consisting of a divalent group represented by the following general formula (2),

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group or a perfluoroalkyl group). The polyimide film of claim 1 or 4 of the scope of the application, wherein the polyimide contains an aromatic ring, and contains a group selected from (i) fluorine atoms, (ii) aliphatic rings, and (iii) utilization Sulfur At least one of the group consisting of an acyl group or a fluorine-substituted alkylene group that connects aromatic rings to each other. For the polyimide film according to claim 1 or 4, the surface with a relatively large concentration of silicon atoms is used as the close contact surface with the resin-containing layer, and the resin-containing layer contains a radically polymerizable compound and a cationically polymerizable compound. A polymer of at least one of the compounds. For the polyimide film of claim 7 of the scope of the application, the surface with a relatively large concentration of silicon atoms is used as the close contact surface with the resin-containing layer, and the resin-containing layer contains a mixture of a radical polymerizable compound and a cationically polymerizable compound. at least one polymer. A layered product in which the polyimide film of claim 1 or 4 and a resin-containing layer containing a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound are located adjacent to each other. The layered product according to claim 10, wherein the radically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule, and the cationically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule. A compound of at least one of two or more epoxy groups and oxetanyl groups. A surface material for a display, which is the polyimide film of item 1 or 4 of the scope of the patent application, or the polyimide film and a polymer containing at least one of a radically polymerizable compound and a cationically polymerizable compound The resin-containing layer is located adjacent to the laminate. For example, the surface material for display according to claim 12 of the patented scope is used for a flexible display. A layered product in which the polyimide film of claim 8 and a resin-containing layer containing a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound are located adjacent to each other. The layered product according to claim 14, wherein the radically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule, and the cationically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule. A compound of at least one of two or more epoxy groups and oxetanyl groups. A surface material for a display, which is the polyimide film of item 8 of the scope of the patent application, or a resin of the polyimide film and a polymer containing at least one of a radically polymerizable compound and a cationically polymerizable compound A laminate in which layers are located adjacent to each other. For example, the surface material for display according to claim 16 of the patented scope is used for flexible displays.

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