TWI855132B - Polyimide resin composition, polyimide varnish, and polyimide film - Google Patents

Abstract

The present invention provides a polyimide resin composition including a polyimide resin (X) containing a repeating unit represented by formula (1) shown below and a repeating unit represented by formula (2) shown below, and a fluorine-containing polymer (Y). (In formula (1), R¹ to R⁴ each independently represent a monovalent aliphatic group or a monovalent aromatic group, Z¹ and Z² each independently represent a divalent aliphatic group or a divalent aromatic group, r represents a positive integer, and R⁵ represents a tetravalent alicyclic group of 4 to 39 carbon atoms. In formula (2), R⁶ represents a tetravalent alicyclic group of 4 to 39 carbon atoms, and ϕ represents a divalent aliphatic group, alicyclic group, aromatic group, or a combination of these groups, with a total of 2 to 39 carbon atoms, which may have at least one linking group selected from the group consisting of -O-, -SO₂ -, -CO-, -CH₂ -, -C(CH₃ )₂ -, -C₂ H₄ O- and -S-.)

Description

Polyimide resin composition, polyimide varnish, and polyimide film

The present invention relates to a polyimide resin composition, a polyimide varnish, and a polyimide film.

Since polyimide resin has excellent mechanical properties and heat resistance, various uses have been explored in the field of electrical and electronic components. For example, it is expected that the glass substrate used in image display devices such as liquid crystal displays and OLED displays will be replaced with a polyimide film substrate, and polyimide resins with satisfactory performance as optical materials are being developed. For example, Patent Document 1 discloses a polyimide copolymer obtained by reacting an acid dianhydride composed of hexahydropyromellitic anhydride and an aromatic acid dianhydride, and a diamine having an organic group such as a polycyclic aromatic group or a siloxane-containing group, in order to use it as an optical part or a peripheral component of an optical element.

Such a polyimide film is usually produced by applying a varnish containing polyimide and a solvent onto a smooth metal belt, etc., and peeling it off after drying. If the peeling property from the belt is poor, the thickness of the film may be uneven or the surface of the film may be damaged. Therefore, research is conducted to improve the peeling property. For example, Patent Document 2 discloses a method for producing an aromatic polyimide film by casting an aromatic polyamide solution containing a specific phosphate ester on a substrate to form a film, and then applying heat and post-heating the film in order to easily peel it off from a substrate of a self-supporting film. In addition, Patent Document 3 discloses a method for manufacturing an extremely thin polyimide film, which includes a step of applying a polyimide resin precursor solution containing a release agent on a substrate, a drying step, a thermal curing step, and a peeling step. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2017-222745 [Patent Document 2] Japanese Patent Publication No. 60-244507 [Patent Document 3] Japanese Patent Publication No. 2009-226632

[The problem that the invention wants to solve]

As mentioned above, polyimide film is obtained by peeling from a support such as a smooth metal belt, but in the image display device application that requires high transparency and smoothness, slight damage during peeling will become a problem. Among them, the polyimide resin with a low elastic modulus and softness used in flexible devices tends to have poor peeling properties from supports such as belts during film formation, and high peeling properties are particularly required. Although the above-mentioned patent documents 2 and 3 improve the peeling properties by using a release agent, it may be reactive with the resin, and especially in a high temperature and high humidity environment, it will cause problems such as a decrease in the molecular weight of the resin. In addition, a polyimide resin composition is required to have high colorless transparency required for optical materials even when using additives such as release agents. Therefore, the subject of the present invention is to provide a polyimide resin composition that can form a film that has excellent releasability from a support such as a belt, suppresses molecular weight reduction in a high temperature and high humidity environment, and has excellent colorless transparency. [Means for solving the problem]

The inventors of the present invention have found that a composition containing a polyimide resin containing specific repeating units and a fluorine-containing polymer can solve the above-mentioned problems, and thus the invention has been completed.

That is, the present invention relates to the following [1] to [14]. [1] A polyimide resin composition comprising: a polyimide resin (X) comprising repeating units represented by the following formula (1) and repeating units represented by the following formula (2), and a fluorine-containing polymer (Y). [Chemical 1] In formula (1), R ¹ to R ⁴ are independently a monovalent aliphatic group or a monovalent aromatic group, Z ¹ and Z ² are independently a divalent aliphatic group or a divalent aromatic group, r is a positive integer, and R ⁵ is a tetravalent alicyclic group having 4 to 39 carbon atoms. In formula (2), R ⁶ is a tetravalent alicyclic group having 4 to 39 carbon atoms, Φ is a group consisting of a divalent aliphatic group, an alicyclic group, an aromatic group, or a combination thereof having a total carbon number of 2 to 39, and may have at least one selected from the group consisting of -O-, -SO ₂ -, -CO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C ₂ H ₄ O-, and -S- as a bonding group. [2] The polyimide resin composition as described in [1], wherein the content of the fluorinated polymer (Y) is 0.01 to 1 part by mass based on 100 parts by mass of the polyimide resin (X). [3] The polyimide resin composition as described in [1] or [2], wherein the fluorinated polymer (Y) is a fluorinated acrylic polymer. [4] The polyimide resin composition as described in any one of [1] to [3], wherein the ratio of the repeating units represented by the above formula (1) in the polyimide resin (X) is 10 to 50 mol%. [5] A polyimide resin composition as described in any one of [1] to [4], wherein the repeating unit represented by the aforementioned formula (1) is composed of a constituent unit (A-1) derived from a compound represented by the following formula (a-1) and a constituent unit (B-1) derived from a compound represented by the following formula (b-1). [Chemical 2] In formula (b-1), R ¹ to R ⁴ are each independently a monovalent aliphatic group or a monovalent aromatic group, Z ¹ and Z ² are each independently a divalent aliphatic group or a divalent aromatic group, and r is a positive integer. [6] A polyimide resin composition as described in any one of [1] to [5], wherein the repeating unit represented by the aforementioned formula (2) is composed of a structural unit (A-1) derived from a compound represented by the following formula (a-1), and a structural unit (B-2-1) derived from a compound represented by the following formula (b-2-1), a structural unit (B-2-2) derived from a compound represented by the following formula (b-2-2), and a structural unit (B-2-3) derived from a compound represented by the following formula (b-2-3). [Chemistry 3] [7] The polyimide resin composition as described in [5] or [6], wherein the ratio of the constituent units (A-1) in the constituent units derived from tetracarboxylic dianhydride constituting the polyimide resin (X) is 50 mol% or more. [8] The polyimide resin composition as described in any one of [5] to [7], wherein the ratio of the constituent units (B-1) in the constituent units derived from diamine constituting the polyimide resin (X) is 10 to 50 mol%. [9] The polyimide resin composition as described in any one of [6] to [8], wherein the ratio of the constituent units (B-2) in the constituent units derived from diamine constituting the polyimide resin (X) is 50 to 90 mol%. [10] A polyimide resin composition as described in any one of [6] to [9], wherein the constituent unit (B-2) is a constituent unit (B-2-1). [11] A polyimide resin composition as described in any one of [6] to [9], wherein the constituent unit (B-2) is a constituent unit (B-2-2). [12] A polyimide resin composition as described in any one of [6] to [9], wherein the constituent unit (B-2) is a constituent unit (B-2-3). [13] A polyimide varnish, which is prepared by dissolving a polyimide resin composition as described in any one of [1] to [12] in an organic solvent. [14] A polyimide film comprising a polyimide resin composition as described in any one of [1] to [12]. [Effects of the Invention]

According to the present invention, a polyimide resin composition can be provided which can form a film having excellent releasability from a support such as a belt, in which molecular weight reduction is suppressed even in a high temperature and high humidity environment, and which is also excellent in colorlessness and transparency.

[Polyimide resin composition] The polyimide resin composition of the present invention comprises: a polyimide resin (X) comprising a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), and a fluorine-containing polymer (Y). [Chemical 4] In formula (1), R ¹ to R ⁴ are independently a monovalent aliphatic group or a monovalent aromatic group, Z ¹ and Z ² are independently a divalent aliphatic group or a divalent aromatic group, r is a positive integer, and R ⁵ is a tetravalent alicyclic group having 4 to 39 carbon atoms. In formula (2), R ⁶ is a tetravalent alicyclic group having 4 to 39 carbon atoms, Φ is a group consisting of a divalent aliphatic group, an alicyclic group, an aromatic group, or a combination thereof having a total carbon number of 2 to 39, and may have at least one selected from the group consisting of -O-, -SO ₂ -, -CO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C ₂ H ₄ O-, and -S- as a bonding group.

<Polyimide resin (X)> The polyimide resin (X) contained in the polyimide resin composition of the present invention comprises a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2). In formula (1), R1 ^{to R4} are independently a monovalent aliphatic group or a monovalent aromatic group, ^Z1 and ^Z2 are independently a divalent aliphatic group or a divalent aromatic group, r is a positive integer, and ^R5 is a tetravalent alicyclic group having 4 to 39 carbon atoms. In formula (2), ^R6 is a tetravalent alicyclic group having 4 to 39 carbon atoms, and Φ is a group consisting of a divalent aliphatic group, an alicyclic group, an aromatic group, or a combination thereof having a total carbon number of 2 to 39, and may have at least one selected from the group consisting of -O-, _-SO2- , -CO-, _-CH2- , -C( _CH3 ) _2- , _-C2H4O- , and -S- as a _bonding group.

(Repeating units represented by formula (1)) The polyimide resin (X) comprises the repeating units represented by the above formula (1) from the viewpoint of colorless transparency and flexibility. In the above formula (1), ^R1 , ^R2 , ^R3 and ^R4 are each independently a monovalent aliphatic group or a monovalent aromatic group, and at least a part of the hydrogen atoms in these groups may be substituted by fluorine atoms. Examples of the monovalent aliphatic group include: a monovalent saturated alkyl group, a monovalent unsaturated alkyl group, a monovalent alkyloxy group, etc. Examples of the monovalent saturated alkyl group include: an alkyl group having 1 to 22 carbon atoms, for example, a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated alkyl group include: an alkenyl group having 2 to 22 carbon atoms, for example, a vinyl group and a propenyl group. Examples of monovalent alkoxy groups include: alkoxy groups having 1 to 22 carbon atoms, such as monovalent groups formed by bonding oxygen atoms to the alkyl groups exemplified above. Examples of monovalent aromatic groups include: aryl groups having 6 to 24 carbon atoms, aralkyl groups having 7 to 24 carbon atoms, aryloxy groups having 6 to 24 carbon atoms, and examples thereof include phenyl and phenoxy groups. ^R1 , ^R2 , ^R3 , and ^R4 are preferably methyl groups or phenyl groups. ^Z1 and ^Z2 are independently divalent aliphatic groups or divalent aromatic groups, and at least a part of hydrogen atoms in these groups may be substituted with fluorine atoms. Examples of divalent aliphatic groups include: divalent saturated alkyl groups or divalent unsaturated alkyl groups. Examples of divalent saturated alkyl groups include alkylene groups having 1 to 22 carbon atoms, such as methylene, ethylene, propylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, and dodecamethylene. Examples of divalent unsaturated alkyl groups include unsaturated carbon hydrogen groups having 2 to 22 carbon atoms, such as vinylene, propyleneene, and alkylene groups having an unsaturated double bond at the terminal. Examples of divalent aromatic groups include arylene groups having 6 to 24 carbon atoms, arylalkylene groups having 7 to 24 carbon atoms, and aryloxy groups having 6 to 24 carbon atoms. At least a portion of the hydrogen atoms constituting the aromatic ring in these groups may be substituted with an alkyl group. Specific examples of arylene groups having 6 to 24 carbon atoms in ^Z1 and ^Z2 include o-phenylene, m-phenylene, p-phenylene, 4,4'-biphenylene, 2,6-naphthylene, etc. Specific examples of arylene alkyl groups having 7 to 24 carbon atoms include benzylene, phenylethylene, etc. Specific examples of aryleneoxy groups having 6 to 24 carbon atoms include divalent groups formed by bonding an oxygen atom to the arylene groups exemplified above. ^Z1 and ^Z2 are preferably propylene, trimethylene, tetramethylene, p-phenylene, benzylene, and more preferably trimethylene, tetramethylene, p-phenylene. In addition, r is a positive integer, preferably an integer of 2 to 50. When r is 2 or more, multiple ^R1 and ^R2 may be the same or different from each other. ^R5 is a tetravalent alicyclic group having 4 to 39 carbon atoms, preferably a tetravalent alicyclic group having 4 to 8 carbon atoms, more preferably a tetravalent alicyclic group having 4 to 6 carbon atoms, and even more preferably a tetravalent alicyclic group having 6 carbon atoms.

The ratio of the repeating units represented by the above formula (1) in the polyimide resin (X) is preferably 10 to 50 mol %, more preferably 10 to 40 mol %, even more preferably 15 to 30 mol %, and particularly preferably 15 to 25 mol %.

In view of colorless transparency and flexibility, the polyimide resin (X) preferably has a repeating unit represented by the above formula (1) composed of a constituent unit (A-1) derived from a compound represented by the following formula (a-1) and a constituent unit (B-1) derived from a compound represented by the following formula (b-1). [Chemistry 6] In formula (b-1), R ¹ to R ⁴ are each independently a monovalent aliphatic group or a monovalent aromatic group, Z ¹ and Z ² are each independently a divalent aliphatic group or a divalent aromatic group, and r is a positive integer.

The compound represented by formula (a-1) is 1,2,4,5-cyclohexanetetracarboxylic dianhydride. The polyimide resin (X) contributes to the improvement of the colorless transparency of the film by including the constituent unit (A-1).

R ¹ to R ⁴ , Z ¹ , Z ² and r in formula (b-1) have the same meanings as R ¹ to R ⁴ , Z ¹ , Z ² and r in the aforementioned formula (1), respectively.

The compounds represented by formula (b-1) include: 1,3-bis(3-aminopropyl)-1,1,2,2-tetramethyldisiloxane, 1,3-bis(3-aminobutyl)-1,1,2,2-tetramethyldisiloxane, 1,3-bis(4-aminophenoxy)tetramethyldisiloxane, 1,1,3,3-tetramethyl-1,3-bis(4-aminophenyl)disiloxane, 1,1,3,3-tetraphenoxy-1,3-bis(2-aminoethyl)disiloxane, 1,1,3,3-tetraphenyl-1,3-bis(2 -aminoethyl) disiloxane, 1,1,3,3-tetraphenyl-1,3-bis(3-aminopropyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis(2-aminoethyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis(3-aminopropyl) disiloxane, 1,1,3,3-tetramethyl-1,3-bis(4-aminobutyl) disiloxane, 1,3-dimethyl-1,3-dimethoxy-1,3-bis(4-aminobutyl) disiloxane, 1,1,3,3,5,5-hexadecene Methyl-1,5-bis(4-aminophenyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetraphenyl-3,3-dimethoxy-1,5-bis(5-aminopentyl)trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(2-aminoethyl)trisiloxane, 1, 1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(4-aminobutyl)trisiloxane, 1,1,5,5-tetramethyl-3,3-dimethoxy-1,5-bis(5-aminopentyl)trisiloxane, 1,1,3,3,5,5-hexamethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexaethyl-1,5-bis(3-aminopropyl)trisiloxane, 1,1,3,3,5,5-hexapropyl-1,5-bis(3-aminopropyl)trisiloxane, etc. The compound represented by formula (b-1) may be used alone or in combination of two or more. As for the compounds represented by formula (b-1) that can be obtained in the form of commercial products, there are: "X-22-9409", "X-22-1660B", "X-22-161AS", "X-22-161A", "X-22-161B" and the like manufactured by Shin-Etsu Chemical Co., Ltd. The polyimide resin (X) contributes to the low elastic modulus of the film by including the constituent unit (B-1).

(Repeating units represented by formula (2)) The polyimide resin (X) comprises the repeating units represented by the aforementioned formula (2). In the aforementioned formula (2), ^R6 is a tetravalent alicyclic group having 4 to 39 carbon atoms, preferably a tetravalent alicyclic group having 4 to 8 carbon atoms, more preferably a tetravalent alicyclic group having 4 to 6 carbon atoms, and even more preferably a tetravalent alicyclic group having 6 carbon atoms. Φ is a group composed of a divalent aliphatic group, an alicyclic group, an aromatic group, or a combination thereof having a total carbon number of 2 to 39, preferably a group having an aromatic group. Furthermore, Φ may have at least one selected from the group consisting of -O-, -SO ₂ -, -CO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C ₂ H ₄ O-, and -S- as a bonding group, and preferably has -O- as a bonding group.

In view of colorless transparency, the polyimide resin (X) preferably has a repeating unit represented by the aforementioned formula (2) composed of a constituent unit (A-1) derived from a compound represented by the aforementioned formula (a-1), and a constituent unit (B-2) derived from at least one selected from the group consisting of a constituent unit (B-2-1) derived from a compound represented by the following formula (b-2-1), a constituent unit (B-2-2) derived from a compound represented by the following formula (b-2-2), and a constituent unit (B-2-3) derived from a compound represented by the following formula (b-2-3). [Chemistry 7]

The compound represented by formula (b-2-1) is 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. The compound represented by formula (b-2-2) is 2,2-bis[4-(4-aminophenoxy)phenyl]propane. The compound represented by formula (b-2-3) is 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-5-amine. In the present invention, the polyimide resin (X) can improve the glass transition temperature of the film by including the constituent unit (B-2). In particular, the constituent unit (B-1) contributes to the low elastic modulus of the film, but on the other hand, it also has a negative effect of lowering the glass transition temperature. Therefore, by including the constituent unit (B-2), the decrease in the glass transition temperature caused by the constituent unit (B-1) can be reduced, and the glass transition temperature of the film can be controlled. In addition, from the perspective of obtaining a film having excellent colorless transparency, the polyimide resin (X) also preferably includes the constituent unit (B-2).

The constituent unit (B-2) may be only the constituent unit (B-2-1), only the constituent unit (B-2-2), or only the constituent unit (B-2-3). Furthermore, the constituent unit (B-2) may be a combination of the constituent unit (B-2-1) and the constituent unit (B-2-2), a combination of the constituent unit (B-2-2) and the constituent unit (B-2-3), or a combination of the constituent unit (B-2-1) and the constituent unit (B-2-3). Furthermore, the constituent unit (B-2) may be a combination of the constituent unit (B-2-1), the constituent unit (B-2-2), and the constituent unit (B-2-3).

(Ratio of each constituent unit and other constituent units) The ratio of constituent unit (A-1) in the constituent unit derived from tetracarboxylic dianhydride (hereinafter also referred to as "constituent unit A") constituting the polyimide resin (X) is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the ratio of constituent unit (A-1) is not particularly limited, that is, 100 mol%. Constituent unit A may also be composed of constituent unit (A-1) alone.

The constituent unit A may include constituent units other than the constituent unit (A-1). The tetracarboxylic dianhydride providing such a constituent unit is not particularly limited, and examples thereof include: aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride; alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (but excluding compounds represented by formula (a-1)); and aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride. In addition, in this specification, aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more alicyclic rings and no aromatic ring, and aliphatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing neither an aromatic ring nor an alicyclic ring. The constituent units other than the constituent unit (A-1) arbitrarily contained in the constituent unit A may be one type or two or more types. In addition, one embodiment of the polyimide resin (X) may be a polyimide resin in which the constituent unit A does not contain a constituent unit derived from 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride.

The ratio of the constituent unit (B-1) in the constituent unit derived from diamine (hereinafter also referred to as "constituent unit B") constituting the polyimide resin (X) is preferably 10 to 50 mol%, more preferably 10 to 40 mol%, even more preferably 15 to 30 mol%, and particularly preferably 15 to 25 mol%. The ratio of the constituent unit (B-2) in the constituent unit B is preferably 50 to 90 mol%, more preferably 60 to 90 mol%, even more preferably 70 to 85 mol%, and particularly preferably 75 to 85 mol%. The total ratio of the constituent unit (B-1) and the constituent unit (B-2) in the constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total ratio of the constituent units (B-1) and (B-2) is not particularly limited, and is 100 mol %. The constituent unit B may be composed only of the constituent units (B-1) and (B-2).

Constituent unit B may also include constituent units other than constituent units (B-1) and (B-2). The diamines that provide such constituent units are not particularly limited, and examples thereof include: 1,4-phenylenediamine, p-phenylenediamine, 3,5-diaminobenzoic acid, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 4,4'-diaminobenzanilide, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, N,N'-bis(4-aminophenyl)-1,4-diisopropylbenzene, Aromatic diamines such as bis(4-aminophenyl)diphenylamine, 4,4'-bis(4-aminophenoxy)biphenyl, and 9,9-bis(4-aminophenyl)fluorene (but excluding compounds represented by formula (b-1), compounds represented by formula (b-2-1), compounds represented by formula (b-2-2), and compounds represented by formula (b-2-3)); alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane and 1,4-bis(aminomethyl)cyclohexane; and aliphatic diamines such as ethylenediamine and hexamethylenediamine (but excluding compounds represented by formula (b-1)). In addition, in this specification, aromatic diamine means a diamine containing one or more aromatic rings, alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic ring, and aliphatic diamine means a diamine containing neither an aromatic ring nor an alicyclic ring. The constituent units other than the constituent units (B-1) and (B-2) arbitrarily contained in the constituent unit B may be one type or two or more types.

(Characteristics of polyimide resin (X)) The number average molecular weight of polyimide resin (X) is preferably 5,000 to 100,000 from the viewpoint of the mechanical strength of the obtained polyimide film. In addition, the number average molecular weight of polyimide resin can be obtained, for example, by using the standard polymethyl methacrylate (PMMA) conversion value measured by gel filtration analysis.

By using the polyimide resin (X), a colorless and highly transparent film can be formed. The ideal physical properties of the film obtained by using the polyimide resin (X) are as follows.

The tensile modulus of the polyimide resin (X) is preferably 2.1 GPa or less, more preferably 2.0 GPa or less, and even more preferably 1.8 GPa or less. When the tensile modulus falls within this range, a polyimide film having high flexibility and suitable for flexible displays can be obtained. The tensile strength is preferably 40 MPa or more, more preferably 50 MPa or more, and even more preferably 60 MPa or more. The tensile modulus and tensile strength are values measured in accordance with JIS K7127, and can be measured, for example, using a tensile tester "STROGRAPH VG-1E" manufactured by Toyo Seiki Co., Ltd. The total light transmittance is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more when a film having a thickness of 30 μm is prepared. When a film having a thickness of 30 μm is prepared, the haze is preferably 1.0% or less, preferably 0.5% or less, and more preferably 0.3% or less. When a film having a thickness of 30 μm is prepared, the yellowness index (YI) is preferably 6.0 or less, preferably 3.0 or less, and more preferably 1.5 or less. The total light transmittance, haze, and yellowness index (YI) can be specifically measured by the method described in the embodiment. When a film having a thickness of 30 μm is prepared, the absolute value of the thickness retardation (Rth) is preferably 100 nm or less, preferably 50 nm or less, and more preferably 30 nm or less. The glass transition temperature (Tg) is preferably 150~300°C, preferably 150~280°C, and more preferably 150~250°C.

(Production method of polyimide resin (X)) The polyimide resin (X) can be produced by reacting a tetracarboxylic acid component containing a compound providing a repeating unit represented by the aforementioned formula (1) with a diamine component and a tetracarboxylic acid component containing a compound providing a repeating unit represented by the aforementioned formula (2) with a diamine component. Among them, it is more preferable to produce by reacting a tetracarboxylic acid component containing a compound providing a constituent unit (A-1) with a diamine component containing a compound providing a constituent unit (B-1) and a compound providing a constituent unit (B-2).

The compound providing the constituent unit (A-1) may be a compound represented by formula (a-1), but is not limited thereto and may be a derivative thereof within the scope of providing the same constituent unit. The derivative may be a tetracarboxylic acid corresponding to the tetracarboxylic dianhydride represented by formula (a-1) (i.e., 1,2,4,5-cyclohexanetetracarboxylic acid) and an alkyl ester of the tetracarboxylic acid. The compound providing the constituent unit (A-1) is preferably a compound represented by formula (a-1) (i.e., dianhydride).

The tetracarboxylic acid component preferably contains more than 50 mol% of the compound providing the constituent unit (A-1), more preferably more than 70 mol%, more preferably more than 90 mol%, and particularly preferably more than 99 mol%. The upper limit of the content of the compound providing the constituent unit (A-1) is not particularly limited, that is, 100 mol%. The tetracarboxylic acid component may also consist only of the compound providing the constituent unit (A-1).

The tetracarboxylic acid component may also contain compounds other than the compound providing the constituent unit (A-1), and the compounds may include the above-mentioned aromatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aliphatic tetracarboxylic dianhydride, and their derivatives (tetracarboxylic acids, alkyl esters of tetracarboxylic acids, etc.). The compounds other than the compound providing the constituent unit (A-1) arbitrarily contained in the tetracarboxylic acid component may be one or more.

The compound providing the constituent unit (B-1) may be a compound represented by formula (b-1), but is not limited thereto and may be a derivative thereof within the scope of providing the same constituent unit. The derivative may be a diisocyanate corresponding to the diamine represented by formula (b-1). The compound providing the constituent unit (B-1) is preferably a compound represented by formula (b-1) (i.e., a diamine).

The compound providing the constituent unit (B-2) is at least one selected from the group consisting of a compound providing the constituent unit (B-2-1), a compound providing the constituent unit (B-2-2), and a compound providing the constituent unit (B-2-3). The compound providing the constituent unit (B-2-1), the compound providing the constituent unit (B-2-2), and the compound providing the constituent unit (B-2-3) can be respectively listed as: a compound represented by formula (b-2-1), a compound represented by formula (b-2-2), and a compound represented by formula (b-2-3), but it is not limited to these, and they may also be derivatives thereof within the scope of providing the same constituent unit. The derivatives include: diisocyanates corresponding to diamines represented by compounds of formula (b-2-1), diisocyanates corresponding to diamines represented by compounds of formula (b-2-2), and diisocyanates corresponding to diamines represented by compounds of formula (b-2-3). The compound providing the constituent unit (B-2-1), the compound providing the constituent unit (B-2-2), and the compound providing the constituent unit (B-2-3) are preferably the compound represented by formula (b-2-1) (i.e., diamine), the compound represented by formula (b-2-2) (i.e., diamine), and the compound represented by formula (b-2-3) (i.e., diamine), respectively.

The compound providing the constituent unit (B-2) may be only the compound providing the constituent unit (B-2-1), only the compound providing the constituent unit (B-2-2), or only the compound providing the constituent unit (B-2-3). In addition, the compound providing the constituent unit (B-2) may be a combination of a compound providing the constituent unit (B-2-1) and a compound providing the constituent unit (B-2-2), a combination of a compound providing the constituent unit (B-2-2) and a compound providing the constituent unit (B-2-3), or a combination of a compound providing the constituent unit (B-2-1) and a compound providing the constituent unit (B-2-3). Furthermore, the compound providing the constitutional unit (B-2) may be a combination of a compound providing the constitutional unit (B-2-1), a compound providing the constitutional unit (B-2-2), and a compound providing the constitutional unit (B-2-3).

The diamine component preferably contains 10 to 50 mol% of the compound providing the constituent unit (B-1), preferably 10 to 40 mol%, more preferably 15 to 30 mol%, and particularly preferably 15 to 25 mol%. The diamine component preferably contains 50 to 90 mol% of the compound providing the constituent unit (B-2), preferably 60 to 90 mol%, more preferably 70 to 85 mol%, and particularly preferably 75 to 85 mol%. In the diamine component, the total of the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2) preferably contains 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, and particularly preferably 99 mol% or more. The upper limit of the total content of the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2) is not particularly limited, that is, 100 mol%. The diamine component may also be composed only of the compound providing the constituent unit (B-1) and the compound providing the constituent unit (B-2).

The diamine component may also contain compounds other than the compounds providing the constituent unit (B-1) and the compounds providing the constituent unit (B-2), and the compounds may include the above-mentioned aromatic diamines, alicyclic diamines, and aliphatic diamines, and their derivatives (diisocyanates, etc.). The compounds other than the compounds providing the constituent unit (B-1) and the compounds providing the constituent unit (B-2) arbitrarily contained in the diamine component may be one or more.

In the present invention, the feed ratio of the tetracarboxylic acid component to the diamine component used in the preparation of the polyimide resin (X) is preferably 0.9-1.1 mol of the diamine component to 1 mol of the tetracarboxylic acid component.

Furthermore, in the present invention, in order to manufacture the polyimide resin (X), in addition to using the aforementioned tetracarboxylic acid component and diamine component, an end-capping agent may also be used. The end-capping agent is preferably a monoamine or a dicarboxylic acid. The amount of the introduced end-capping agent is preferably 0.0001 to 0.1 mole, and is particularly preferably 0.001 to 0.06 mole relative to 1 mole of the tetracarboxylic acid component. Monoamine end-capping agents are recommended, for example: methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc. Among them, benzylamine and aniline can be used ideally. The dicarboxylic acid end-capping agent is preferably a dicarboxylic acid, and a portion thereof may also be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. Among them, phthalic acid and phthalic anhydride are preferably used.

The method for reacting the tetracarboxylic acid component and the diamine component is not particularly limited, and a known method can be used. Specific reaction methods include: (1) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are fed into a reactor, stirred at room temperature to 80°C for 0.5 to 30 hours, and then the temperature is raised to carry out an imidization reaction; (2) a method in which a diamine component and a reaction solvent are fed into a reactor and dissolved, and then a tetracarboxylic acid component is fed, and stirred at room temperature to 80°C for 0.5 to 30 hours as needed, and then the temperature is raised to carry out an imidization reaction; (3) a method in which a tetracarboxylic acid component, a diamine component, and a reaction solvent are fed into a reactor, and the temperature is immediately raised to carry out an imidization reaction, etc.

The reaction solvent used in the production of the polyimide resin (X) may be any solvent that does not hinder the imidization reaction and can dissolve the generated polyimide, for example, aprotic solvents, phenolic solvents, etheric solvents, carbonate solvents, etc.

Specific examples of aprotic solvents include: amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactone, 1,3-dimethylimidazolidinone, and tetramethylurea; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphatamide and hexamethylphosphotriamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and cyclobutane sulfone; ketone solvents such as acetone, cyclohexanone, and methylcyclohexanone; amine solvents such as picolinyl and pyridine; ester solvents such as 2-methoxy-1-methylethyl acetate, etc.

Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, etc. Specific examples of etheric solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, 1,4-dioxane, etc. Moreover, specific examples of carbonate-based solvents include diethyl carbonate, ethyl methyl carbonate, ethyl carbonate, propyl carbonate, etc. Among the above reaction solvents, amide solvents or lactone solvents are preferred. The above reaction solvents may be used alone or in combination of two or more.

The imidization reaction is preferably carried out using a Dean-Stark apparatus or the like, while removing water generated during the production. By carrying out such an operation, the degree of polymerization and the imidization rate can be further increased.

In the above-mentioned imidization reaction, a known imidization catalyst can be used. The imidization catalyst can be a base catalyst or an acid catalyst. The base catalyst can be: pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-dipicoline, 2,6-dipicoline, trimethylamine, triethylamine, tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, N,N-diethylaniline and other organic base catalysts; potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate and other inorganic base catalysts. In addition, the acid catalyst can be exemplified by: crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, etc. The above imidization catalyst can be used alone or in combination of two or more. Among the above, considering the operability, it is preferable to use an alkaline catalyst, and it is more preferable to use an organic alkaline catalyst, and it is even more preferable to use triethylamine, and it is particularly preferable to use a combination of triethylamine and triethylenediamine.

The temperature of the imidization reaction is preferably 120 to 250° C., more preferably 160 to 200° C., from the viewpoint of reaction rate and inhibition of gelation. The reaction time is preferably 0.5 to 10 hours after the distillation of generated water begins.

<Fluorine-containing polymer (Y)> The fluorine-containing polymer (Y) in the present invention is preferably a polymer having a constituent unit derived from a fluorine-containing monomer, and more preferably a polymer having a constituent unit derived from a fluorinated alkyl group-containing monomer. The fluorine-containing polymer (Y) in the present invention is preferably a fluorine-containing acrylic polymer.

The fluorine-containing acrylic polymer preferably includes constituent units derived from fluorine-containing acrylic monomers, and more preferably includes constituent units derived from fluorine-containing acrylic monomers and constituent units derived from acrylic monomers having a hydrophilic group.

The fluorine-containing acrylic monomer is preferably a monomer having a perfluoroalkyl group. Examples of acrylic monomers having a hydrophilic group include acrylic acid, methacrylic acid, hydroxyalkyl (meth)acrylate, polyalkylene glycol (meth)acrylate, acrylamide, methacrylamide, etc. The fluorine-containing acrylic polymer may also include an acrylic monomer having a hydrophobic group. Examples of acrylic monomers having a hydrophobic group include alkyl (meth)acrylate, polysilicone-containing (meth)acrylate, aryl (meth)acrylate, etc. Here, "(meth)acrylate" means "acrylate or methacrylate". Other monomers having a vinyl group may also be copolymerized in the fluorine-containing acrylic monomer. By using a fluorine-containing polymer in the polyimide resin composition of the present invention, even if a polyimide having a polysiloxane portion that is easily hydrolyzed in a high temperature and high humidity environment and has flexibility is used in the polyimide skeleton, there is almost no molecular weight reduction, and the peeling property from a support such as a belt is also good. In addition, the transparency of the obtained film is also excellent.

Commercially available products of the fluorine-containing polymer (Y) include LE-605, LE-607, LE-605DM, LE-607DM, etc. manufactured by Kyoei Chemical Co., Ltd.

In the polyimide resin composition of the present invention, the content of the fluorine-containing polymer (Y) is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.9 parts by mass, more preferably 0.1 to 0.8 parts by mass, and even more preferably 0.2 to 0.7 parts by mass, relative to 100 parts by mass of the polyimide resin (X).

<Characteristics of polyimide resin composition> By using the polyimide resin composition of the present invention, a film can be formed which has excellent releasability from a support such as a belt, suppresses molecular weight reduction in a high temperature and high humidity environment, and has excellent colorless transparency. The ideal physical property values of the film obtained by using the polyimide resin composition of the present invention are as follows.

When a film with a thickness of 30 μm is made, the total light transmittance is preferably 85% or more, preferably 88% or more, and even more preferably 90% or more. When a film with a thickness of 30 μm is made, the haze is preferably 1.0% or less, preferably 0.5% or less, and even more preferably 0.3% or less. When a film with a thickness of 30 μm is made, the yellowness index (YI) is preferably 6.0 or less, preferably 3.0 or less, and even more preferably 1.5 or less. The total light transmittance, haze, and yellowness index (YI) can be specifically measured by the method described in the embodiment. When a film with a thickness of 30 μm is made, the absolute value of the thickness retardation (Rth) is preferably 100 nm or less, preferably 50 nm or less, and even more preferably 30 nm or less. The glass transition temperature (Tg) is preferably 150-300°C, more preferably 150-280°C, and even more preferably 150-250°C. In addition, the tensile modulus is preferably 2.1 GPa or less, more preferably 2.0 GPa or less, and even more preferably 1.8 GPa or less. When the tensile modulus is within this range, a polyimide film having high flexibility and suitable for flexible displays, etc. can be produced. The tensile strength is preferably 40 MPa or more, more preferably 50 MPa or more, and even more preferably 60 MPa or more. The tensile modulus and tensile strength are values measured in accordance with JIS K7127, and can be measured, for example, using a tensile testing machine "STROGRAPH VG-1E" manufactured by Toyo Seiki Co., Ltd.

[Polyimide varnish] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin composition of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin composition of the present invention and an organic solvent, and the polyimide resin composition is dissolved in the organic solvent. The organic solvent is not particularly limited as long as it can dissolve the polyimide resin (X) and the fluorine-containing polymer (Y). It is preferable to use the above-mentioned reaction solvent compound used for the production of the polyimide resin alone or in combination of two or more. The polyimide varnish of the present invention may be a polyimide solution obtained by dissolving a polyimide resin (X) obtained by a polymerization method in a reaction solvent, or may be a polyimide solution obtained by adding a diluting solvent.

The polyimide resin composition of the present invention has solvent solubility, so a stable high-concentration varnish can be prepared at room temperature. The polyimide varnish of the present invention preferably contains 5-40% by mass of the polyimide resin (X), and preferably contains 10-30% by mass. In addition, the fluorine-containing polymer (Y) preferably contains 0.003-0.3% by mass, preferably 0.015-0.3% by mass, more preferably 0.03-0.25% by mass, and even more preferably 0.08-0.2% by mass relative to 100% by mass of the polyimide resin (X). The viscosity of the polyimide varnish is preferably 1-200 Pa･s, and preferably 5-150 Pa･s. The viscosity of the polyimide varnish is a value measured at 25°C using an E-type viscometer.

Furthermore, the polyimide varnish of the present invention may also contain various additives such as inorganic fillers, adhesion promoters, flame retardants, ultraviolet absorbers, surfactants, leveling agents, defoaming agents, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitizers within the range that the properties required of the polyimide film are not impaired. The method for preparing the polyimide varnish of the present invention is not particularly limited, and a known method can be used.

Any appropriate ultraviolet absorber can be used as the ultraviolet absorber exemplified in the above-mentioned additives. Specific examples thereof include: benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, benzoate ultraviolet absorbers, tris(II) ultraviolet absorbers, hindered amine ultraviolet absorbers, inorganic particle ultraviolet absorbers, and other organic ultraviolet absorbers such as oxalylaniline ultraviolet absorbers and malonate ultraviolet absorbers. Only one ultraviolet absorber can be used, or two or more ultraviolet absorbers can be used in combination. Among them, benzotriazole ultraviolet absorbers and tris(II) ultraviolet absorbers are preferred, and benzotriazole ultraviolet absorbers are more preferred.

The amount of the ultraviolet absorber added to the resin composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.5 to 4 parts by mass relative to 100 parts by mass of the polyimide resin (X). If the amount of the ultraviolet absorber is large, the properties of the polyimide resin such as optical properties and heat resistance may be reduced, or the film may produce haze. In the present invention, the ultraviolet absorber is a compound that can achieve the effect of the ultraviolet absorber in the resin composition. Therefore, the compound added as the ultraviolet absorber can maintain its structure and exist in the resin composition, or it can be modified into a modified compound that still has the effect of ultraviolet absorption after heat treatment. In addition, the ultraviolet absorber is preferably uniformly mixed with the polyimide resin (X) in the resin composition.

[Polyimide film] The polyimide film of the present invention contains the polyimide resin composition of the present invention. Therefore, the polyimide film of the present invention has excellent colorless transparency, and the molecular weight does not decrease even in a high temperature and humid environment, so the storage stability is also excellent. The ideal physical property values of the polyimide film of the present invention are shown in <Characteristics of the polyimide resin composition>.

The method for producing the polyimide film of the present invention is not particularly limited, and a known method can be used. For example, the polyimide varnish of the present invention is applied to a smooth support such as a glass plate, a metal plate, or a plastic, or formed into a film, and then the organic solvents such as the reaction solvent and the dilution solvent contained in the varnish are removed by heating, and then the film is peeled off from the support. Industrially, it is preferable to apply the polyimide varnish to a metallic belt, and then remove the organic solvent contained in the varnish by heating, and then peel it off from the belt. As for the organic solvent, it is preferable to evaporate the organic solvent at a temperature below 120°C, and then peel it off from the support after forming a self-supporting film. The polyimide resin composition of the present invention has excellent peeling property from the support, so even if the obtained self-supporting film is soft, it can be peeled without damaging the film. Then, the end of the self-supporting film peeled from the support is preferably fixed, and dried at a temperature above the boiling point of the organic solvent used to produce the polyimide film. In addition, it is suitable to dry in a nitrogen environment. The pressure of the drying environment can be any of reduced pressure, normal pressure, and pressurized. There is no special restriction on the heating temperature when drying the self-supporting film to produce the polyimide film, and it is preferably 200~400℃.

The thickness of the polyimide film of the present invention can be appropriately selected according to the application, etc., preferably 1 to 250 μm, more preferably 5 to 100 μm, and even more preferably 10 to 80 μm. If the thickness is 1 to 250 μm, it is possible to use it as a self-supporting film. The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish.

The polyimide film of the present invention can be ideally used as a film for various components such as color filters, flexible displays, semiconductor parts, optical components, etc. The polyimide film of the present invention can be particularly ideally used as a substrate for image display devices such as liquid crystal displays and OLED displays. [Example]

The present invention is specifically described below using examples. However, the present invention is not limited to these examples. The solid content concentration of the polyimide varnish obtained in the examples and comparative examples and the various physical properties of the polyimide film are measured using the methods shown below, and various evaluations of the polyimide film are performed.

(1) Solid content concentration The solid content concentration was calculated by heating the sample at 320°C for 120 min using a small electric furnace "MMF-1" manufactured by AS ONE Co., Ltd. and calculating the mass difference between the sample before and after heating. (2) Film thickness The film thickness was measured using a micrometer manufactured by Mitutoyo Corporation. (3) Peelability As described in each embodiment and comparative example, a polyimide varnish was applied to a SUS substrate processed with #1000 and kept at 100°C for 20 minutes to allow the solvent to evaporate, thereby obtaining a primary dried film. Whether the primary dried film could be peeled off from the SUS substrate was evaluated. In Table 1, peelable was 0 and non-peelable was ×. Here, "unpeelable" refers to those in which the adhesion between the SUS substrate and the film is strong and a portion of the primary drying film is destroyed during peeling. (4) Logarithmic viscosity of polyimide film The logarithmic viscosity of polyimide film is obtained by preparing a solution in which the polyimide film is uniformly dissolved in N-methyl-2-pyrrolidone at a concentration of 0.5 g/dL, and measuring the solution viscosity of the solution and the solvent at 30°C using a Cannon-Fenske viscometer. The viscosity is then calculated using the following formula. Logarithmic viscosity = [ln (viscosity of polyimide film preparation solution / viscosity of solvent)] / concentration of solution (5) Wet and hot environment test (evaluation of molecular weight change) The polyimide film was treated in a constant temperature and humidity machine at a temperature of 60°C and a humidity of 90%RH for 120 hours. Thereafter, the logarithmic viscosity after the wet and hot environment test was measured in the same way as the logarithmic viscosity of the polyimide film (4). The difference in logarithmic viscosity before and after the wet and hot environment test of the polyimide film obtained in this way was calculated to evaluate the molecular weight change. The smaller the difference in logarithmic viscosity before and after the wet and hot environment test, the more the molecular weight reduction was suppressed. (6) Total light transmittance, yellowness index (YI) and haze Total light transmittance, YI and haze were measured using the color-turbidity simultaneous measuring instrument "COH400" manufactured by Nippon Denshoku Industries Co., Ltd. The measurement of total light transmittance and YI was carried out in accordance with JIS K7361-1:1997, and the measurement of haze was carried out in accordance with JIS K7136:2000.

The tetracarboxylic acid component and diamine component used as raw materials of the polyimide resin in the examples and comparative examples and their abbreviations are as follows. <Tetracarboxylic acid component> HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (manufactured by Mitsubishi Gas Chemical Co., Ltd.; compound represented by formula (a-1)) <Diamine component> X-22-9409: Silicone oil "X-22-9409" with amino groups modified at both ends (manufactured by Shin-Etsu Chemical Co., Ltd.; compound represented by formula (b-1)) HFBAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (manufactured by SEIKA Co., Ltd.; compound represented by formula (b-2-1))

<Example 1> In a 0.3L 5-necked glass round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet pipe, a Dean-Stark apparatus equipped with a cooling tube, a thermometer, and glass end caps, 29.034g (0.056 mol) of HFBAPP, 18.76g (0.014 mol) of X-22-9409, 50g of γ-butyrolactone (Mitsubishi Chemical Co., Ltd.), and 0.039g of triethylenediamine (Tokyo Chemical Industry Co., Ltd.) as a catalyst and 3.54g of triethylamine (Kanto Chemical Co., Ltd.) were stirred at 200rpm under a nitrogen environment to obtain a solution. After adding 15.692g (0.070 mol) of HPMDA and 13.5g of γ-butyrolactone (Mitsubishi Chemical Co., Ltd.) to the solution at once, the temperature in the reaction system was raised to 200°C in about 20 minutes using a mantle heater. The exuded components were collected and the temperature in the reaction system was maintained at 200°C for 3 hours. After adding 78.76g of N,N-dimethylacetamide (Mitsubishi Gas Chemical Co., Ltd.), the mixture was stirred at about 100°C for about 1 hour to obtain a uniform polyimide solution with a solid content concentration of 30% by mass. To the obtained polyimide solution, 0.5 parts by mass (effective fraction conversion) of a fluorine-containing polymer (LE-607DM, manufactured by Kyoeisha Chemical Co., Ltd., 30% dimethylacetamide solution) was added relative to 100 parts by mass of the polyimide resin to obtain a polyimide varnish.

Then, by applying the obtained polyimide varnish on a SUS substrate processed with #1000, and keeping it at 100°C for 20 minutes to allow the solvent to evaporate, a self-supporting colorless and transparent once-dried film is obtained. When the polyimide film is peeled off from the SUS plate, the aforementioned peeling evaluation is carried out. The film is then fixed on a stainless steel frame and dried for 2 hours in a nitrogen environment at 230°C to remove the solvent, obtaining a film with a thickness of 66μm. The FT-IR analysis of the obtained film confirms the disappearance of the raw material peak and the appearance of the peak from the imide skeleton. The peeling evaluation results and the evaluation results of the polyimide film are shown in Table 1.

<Example 2> A polyimide film with a thickness of 54 μm was obtained by the same method as in Example 1 except that 0.1 mass part (effective fraction conversion) of LE-607DM (fluorine-containing polymer, manufactured by Kyoei Chemical Co., Ltd.) of Example 1 was added to 100 mass parts of polyimide resin. The evaluation results are shown in Table 1.

<Comparative Example 1> Example 1 LE-607DM (fluorine-containing polymer, manufactured by Kyoei Chemical Co., Ltd.) was replaced with 0.2 parts by mass of phosphate-based release agent JP-502 (manufactured by Chengbei Chemical Industry Co., Ltd., diethyl phosphonate: monoethyl phosphonate = 1:1 (molar ratio)) relative to 100 parts by mass of polyimide resin. In addition, a polyimide film with a thickness of 47 μm was obtained by the same method as Example 1. The evaluation results are shown in Table 1.

<Comparative Example 2> A polyimide film with a thickness of 60 μm was obtained by the same method as in Example 1 except that LE-607DM (fluorine-containing polymer, manufactured by Kyoei Chemical Co., Ltd.) was not added. The evaluation results are shown in Table 1.

[Table 1] Embodiment 1 Embodiment 2 Comparison Example 1 Comparison Example 2 Polyimide resin composition (polyimide film) Polyimide resin (X) Tetracarboxylic acid component [mol%] HPMDA 100 100 100 100 Diamine component [mol%] X-22-9409 20 20 20 20 HFBAPP 80 80 80 80 Fluorinated polymer (Y) [weight]*1 LE-607DM 0.5 0.1 - - Phosphate-based release agent [weight] * 1 JP-502 - - 0.2 - Polyimide Film Evaluation Film thickness [μm] 66 54 47 60 Separability ○ ○ ○ × Logarithmic viscosity [dL/g] 0.796 0.821 0.790 0.932 Logarithmic viscosity after wet and hot environment test [dL/g] 0.787 0.811 0.686 0.901 Logarithmic viscosity difference before and after the wet and hot environment test [dL/g] (evaluation of molecular weight change) 0.009 0.010 0.104 0.031 Total light transmittance[%] 90.4 90.5 90.5 90.5 YI 1.7 1.1 1.2 1.3 Fog[%] 0.2 0.1 0.2 0.1 *1: Amount relative to 100 parts by mass of polyimide resin

As shown in Table 1, the polyimide film of the embodiment formed by the polyimide resin composition of the present invention has excellent releasability, the molecular weight reduction is still suppressed in a high temperature and high humidity environment, and the colorless transparency is also excellent.

Claims (11)

A polyimide resin composition comprising: a polyimide resin (X) comprising a repeating unit consisting of a constituent unit (A-1) derived from a compound represented by the following formula (a-1) and a constituent unit (B-1) derived from a compound represented by the following formula (b-1) and a constituent unit (A-1) derived from a compound represented by the following formula (a-1) and a constituent unit selected from a compound represented by the following formula (b-2-1) a fluorine-containing polymer (Y); wherein the fluorine-containing polymer (Y) is a fluorine-containing acrylic polymer;

In formula (b-1), R ¹ to R ⁴ are independently a monovalent aliphatic group or a monovalent aromatic group, Z ¹ and Z ² are independently a divalent aliphatic group or a divalent aromatic group, and r is a positive integer;

The polyimide resin composition of claim 1, wherein the content of the fluorine-containing polymer (Y) is 0.01 to 1 part by mass relative to 100 parts by mass of the polyimide resin (X). A polyimide resin composition as claimed in claim 1 or 2, wherein the ratio of the repeating units represented by the formula (1) in the polyimide resin (X) is 10 to 50 mol%. A polyimide resin composition as claimed in claim 1 or 2, wherein the ratio of the constituent unit (A-1) in the constituent units derived from tetracarboxylic dianhydride constituting the polyimide resin (X) is 50 mol% or more. A polyimide resin composition as claimed in claim 1 or 2, wherein the ratio of the constituent unit (B-1) in the constituent unit derived from diamine constituting the polyimide resin (X) is 10 to 50 mol%. A polyimide resin composition as claimed in claim 1 or 2, wherein the ratio of the constituent unit (B-2) in the constituent unit derived from diamine constituting the polyimide resin (X) is 50 to 90 mol%. The polyimide resin composition of claim 1 or 2, wherein the constituent unit (B-2) is the constituent unit (B-2-1). The polyimide resin composition of claim 1 or 2, wherein the constituent unit (B-2) is the constituent unit (B-2-2). The polyimide resin composition of claim 1 or 2, wherein the constituent unit (B-2) is the constituent unit (B-2-3). A polyimide varnish is prepared by dissolving a polyimide resin composition as described in any one of claims 1 to 9 in an organic solvent. A polyimide film comprising a polyimide resin composition as described in any one of claims 1 to 9.