CN111566151B - Black polyimide film and preparation method thereof - Google Patents

Abstract

The present invention provides a polyimide film, which comprises: 100 parts by weight of polyimide resin; 1 to 5 parts by weight of a first shielding filler with an average particle size of 0.1 μm to 1 μm; and 0.3 parts by weight to 1 part by weight of the second shielding filler, the average particle diameter relative to the horizontal direction is 5 μm to 15 μm, the average particle diameter relative to the vertical direction is 1 nm to 10 nm, and the light transmittance in the visible light region is 7%. Hereinafter, the modulus (modulus) measured in the machine direction (MD) and/or transverse direction (TD) of the polyimide film is 3 GPa or more, and the thickness of the polyimide film is 8.0 μm or less.

Description

Black polyimide film and preparation method thereof

technical field

The invention relates to a black polyimide film and a preparation method thereof.

Background technique

Generally, polyimide (PI) resin refers to the solution polymerization of aromatic dianhydride and aromatic diamine or aromatic diisocyanate to prepare polyamic acid derivatives, dehydration by ring closure at high temperature, and acyl High temperature resistant resin made by imidization.

Polyimide resins are usually composed of aromatic dianhydrides, such as pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA), and aromatic diamine components, such as 4,4'-diphenylamine oxide (ODA), 3,4'-oxidized diphenylamine, p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), methylene dianiline (MDA), bisaminophenylhexafluoro Propane (HFDA) etc. polymerized.

Polyimide resin is an insoluble and non-melting super heat-resistant resin, and has excellent characteristics such as thermal oxidation resistance, heat resistance, radiation resistance, low temperature characteristics, chemical resistance, etc., so it is widely used in Thermal high-tech materials, such as automotive materials, aviation materials, spacecraft materials, etc., and electronic materials, such as insulating coating agents, insulating films, semiconductors, electrode protection films for TFT-LCD, etc.

Recently, it is widely used as a coverlay for portable electronic devices and communication devices.

Cover films are used to protect electronic components such as printed wiring boards and lead frames of semiconductor integrated circuits. Cover films are required not only to secure insulation to a certain degree but also to require mechanical properties to make them thinner and thinner. Recently, in order to obtain Optical characteristics such as shielding properties are also required for safety and visual effects of electronic parts or mounted parts.

On the other hand, with respect to the polyimide resin as described above, it is known as a method for securing optical properties such as shielding properties by dispersing a colored filler such as carbon black in a precursor solution. method for forming thin films.

However, as the content of filler in the film increases, the light transmittance of the polyimide film decreases to improve shielding, but the dielectric constant tends to increase due to the filler.

That is, with respect to the polyimide films prepared by these methods, although the shielding properties are improved as the content of the filler increases, the insulating properties of the polyimide films are reduced, making them unsuitable for use in electronic devices.

Not only that, as the content of the filler in the film increases, the mechanical properties of the polyimide film will decrease, or the film-forming process itself cannot be performed.

Therefore, there is a great need for technologies that can fundamentally solve these problems.

Contents of the invention

The technical problem to be solved by the invention

The object of the present invention is to provide black polyimide film, specifically, provide a kind of following black polyimide film, promptly take the polyimide resin of 100 weight parts as benchmark, described polyimide film Contain 1 to 5 parts by weight of the first shielding filler and 0.3 to 1 part by weight of the second shielding filler, so that even if a small amount of filler is included, the light transmittance can be reduced to improve the shielding property and improve the modulus To ensure mechanical stability while minimizing the dielectric constant.

Means used to solve technical problems

In order to achieve this purpose, the present invention provides a polyimide film, which comprises: 100 parts by weight of polyimide resin; 1 to 5 parts by weight of a first barrier filler, with an average particle size of 0.1 μm to 1 μm; and 0.3 to 1 part by weight of a second shielding filler with an average particle diameter of 5 to 15 μm relative to the horizontal direction and an average particle diameter of 1 to 10 nm relative to the vertical direction, light transmission in the visible light region The ratio is 7% or less, the modulus (modulus) measured in the longitudinal direction (machine direction, MD) and/or transverse direction (transverse direction, TD) of the polyimide film is 3 GPa or more, and the thickness of the polyimide film is 8.0 μm the following.

For the polyimide film according to the present invention, although there is a light transmittance below the required level, the mechanical stability will not be reduced, and the dielectric constant below the required level can be ensured simultaneously, so preferably, it can be used in Used as a cover film in portable electronic and communication equipment.

Embodiments of the present invention will be described in detail below in order of the "polyimide film" and the "preparation method of the polyimide film" according to the present invention.

Until then, the terms or words used herein and in the claims of the invention should not be construed as limited to ordinary or dictionary meanings, but should be based on principles such as the concept that the inventor can properly define the term in order to best explain his invention. , interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Therefore, it should be understood that the structure of the embodiments described herein is only an embodiment of the preferred embodiments of the present invention, and does not represent all technical spirits of the present invention, so as far as the application is concerned, various Equivalent substitutions and modifications.

As used herein, singular forms include plural forms unless the context clearly dictates otherwise. It should be understood that in this document, the terms "comprising", "having" or "having" etc. are intended to specify the presence of implemented features, numbers, steps, structural elements or combinations thereof, and do not exclude one or more other features or Presence or addition of numbers, steps, structural elements or combinations thereof.

polyimide film

As mentioned above, the polyimide film according to the present invention is characterized in that it comprises: 100 parts by weight of polyimide resin; 1 to 5 parts by weight of the first barrier filler, with an average particle diameter of 0.1 μm to 1 μm; and 0.3 parts by weight to 1 part by weight of the second shielding filler, the average particle diameter relative to the horizontal direction is 5 μm to 15 μm, the average particle diameter relative to the vertical direction is 1 nm to 10 nm, and the light transmission in the visible light region The ratio is 7% or less, the modulus (modulus) measured in the longitudinal direction (MD) and/or transverse direction (TD) of the polyimide film is 3 GPa or more, and the thickness of the polyimide film is 8.0 μm or less.

The first shielding filler may be a colored filler, which is used to ensure the shielding of the polyimide film. Specifically, the first shielding filler may be a spherical filler with a sphericity of 0.8 or more. More specifically, the The first barrier filler may be carbon black.

Wherein the spherical filler can be defined as that the shape of the filler is spherical or close to spherical, and the ratio of the average particle diameter to the average short diameter is 1 or close to 1, that is, the degree of sphericity (the short diameter of the filler particle/the particle diameter of the filler particle) is Above 0.8.

In this case, when the content or the average particle size of the first barrier filler is smaller than the above-mentioned range, it is difficult to secure a desired level of barrier properties, which is not preferable.

On the contrary, when the content or the average particle size of the first shielding filler is greater than the above range, the dispersibility will be reduced when mixed with polyamic acid in the preparation process, the filler will protrude from the surface of the film, and the appearance will be poor, and the polyamic acid will have poor appearance. Since the dielectric constant of the imide thin film increases, it is not preferable.

On the other hand, the second shielding filler may be a platy filler for ensuring the shielding of the polyimide film, which satisfies the average particle size relative to the horizontal direction of 5 μm to 15 μm, and the average particle size relative to the vertical direction The particle size is 1 nm to 10 nm. Specifically, the second shielding filler may be graphene.

Among them, the plate-like filler can be defined as a filler whose shape is plate-like or scale-like, and whose average thickness is sufficiently smaller than the average particle diameter or average short diameter of the surface portion, that is, the sphericity (the particle diameter of the filler particles relative to the vertical direction). diameter or short diameter/particle diameter or short diameter relative to the horizontal direction of filler particles) is 0.1 or less.

When forming a polyimide film, such platy fillers can more effectively exhibit light-blocking characteristics according to the orientation or arrangement of the filler particles in the film, so that even a small amount of filler can significantly reduce the Light transmittance of amine films.

In addition, according to the arrangement or orientation of the second shielding filler, the modulus (modulus) measured in the MD and/or TD direction is 3 GPa or more, which can sufficiently ensure mechanical stability, specifically, the modulus measured in the MD direction When the amount is 3 GPa or more, the modulus of elasticity can be increased.

In this case, when the content of the first barrier filler or the average particle size in the horizontal or vertical direction is smaller than the above range, it is difficult to secure a desired level of barrier properties, which is not preferable.

On the contrary, when the content of the second shielding filler, the average particle size in the horizontal direction or the vertical direction is greater than the above range, it is the same as the case of the first shielding filler, and it is mixed with the polyamide during the preparation process. The degree of dispersion decreases when the acid is mixed, so it is difficult to form a film due to a decrease in mechanical properties, and even if a film is produced, poor appearance such as filler protruding from the film surface occurs, so it is not preferable.

In addition, regarding the second shielding filler, when forming a polyimide film, since the dielectric constant of the polyimide film increases rapidly depending on the orientation or arrangement of filler particles in the film, it is not suitable for use as an insulating film. Not preferred.

Preferably, the polyimide film may have a dielectric constant of 5 or less measured at a frequency of 1.1 GHz.

Moreover, the ratio of the content of the second shielding filler to the content of the first shielding filler may be 100% to 1600% by weight, specifically, the content of the second shielding filler relative to A content ratio of the first barrier filler may be 200% to 1,000% by weight, more specifically, may be 300% to 800%.

Therefore, when the polyimide film is applied to a cover film, an insulating film, a semiconductor, etc., not only can the product be made thinner, but also the aesthetics can be improved, and the inner shape and the charging part can be blocked from the external view, thereby effectively Good for security.

Preparation method of polyimide film

The invention provides a method for preparing a polyimide film, comprising: step (a), polymerizing polyamic acid from dianhydride and diamines; step (b), using a grinder to prepare the first film with an average particle size of 0.1 μm to 1 μm. A shielding filler, and a second shielding filler with an average particle diameter of 5 μm to 15 μm relative to the horizontal direction and an average particle diameter of 1 nm to 10 nm relative to the vertical direction; and step (c), the first shielding filler The polyamic acid is mixed with a protective filler and a second shielding filler, and a film is formed on a carrier and heat-treated for imidization.

That is, the polyimide film of the present invention is obtained from a solution of polyamic acid as a precursor of polyimide.

Specifically, the polyamic acid solution can be derived from dianhydride monomers and diamine monomers, and the dianhydride monomers can be selected from pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), At least one or more of the group consisting of oxydiphthalic anhydride (ODPA) and benzophenone tetracarboxylic dianhydride (BTDA), but not limited thereto.

And, the diamine monomer can be selected from 1,4-phenylenediamine (PPD), 4,4'-oxidized diphenylamine (ODA), 3,4'-oxidized diphenylamine, 2,2-bis[ 4'-(4-aminophenoxy)phenyl]propane (BAPP), 4,4'-malondialdehyde (MDA) and 1,3-bis(4-aminophenoxy)benzene (TPE-R) More than one of the group formed, but not limited thereto.

On the other hand, the polyamic acid solution is prepared by mixing an aromatic diamine monomer and an aromatic dianhydride monomer in the monomer compound so as to have substantially equimolar amounts, and dissolving the monomer mixture in an organic solution , at a controlled temperature, the mixed solution is mixed and stirred until the polymerization of the aromatic dianhydride monomer and the aromatic diamine monomer is completed.

The solid content of the polyamic acid solution is usually 5% by weight to 35% by weight, preferably 10% by weight to 30% by weight.

In this concentration range, the polyamic acid solution obtains proper molecular weight and solution viscosity.

The solvent used for synthesizing the polyamic acid solution is not particularly limited, and any solvent that can dissolve the polyamic acid can be used, but an amide solvent is preferred.

Specifically, the solvent may be an organic polar solvent, specifically an aprotic polar solvent, for example, may be selected from N,N'-dimethylformamide (DMF), N,N' - More than one of the group consisting of dimethylacetamide, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL), diglyme (Diglyme), but not limited thereto, can Use alone or in combination of two or more as needed.

In one example, preferably, especially N,N-dimethylformamide and N,N-dimethylacetamide may be used as the solvent.

On the other hand, the particle size of the first barrier filler and the second barrier filler can be controlled by using a bead mill, and these grinding processes allow fillers with relatively low particle size dispersion to be properly mixed with the polyamic acid solution and Dispersion, thereby maintaining the light transmittance evenly on the entire polyimide film prepared, and finally and further reducing the light transmittance.

In addition, in order to improve the dispersibility of the first barrier filler and the second barrier filler and stabilize the dispersed state, a dispersant, a thickener, etc. may be used within the range that does not affect the physical properties of the film.

On the other hand, the catalyst may be further added to the polyamic acid solution, the first barrier filler and the second barrier filler, and then coated on the carrier.

As the catalyst, a dehydration catalyst composed of anhydrous acids such as acetic anhydride and tertiary amines such as isoquinoline, β-picoline, pyridine, etc. can be used, and a mixture of anhydrous acids/amines can be used or in the form of anhydrous acid/amine/solvent mixtures.

The amount of anhydrous acid added can be calculated based on the molar ratio of the o-carboxylamide functional group in the polyamic acid solution, 1.0 to 5.0 moles can be used, and the amount of tertiary amine added can be determined by the polyamic acid solution The molar ratio of the o-carboxamide functional group in the middle is calculated, specifically, 0.2 moles to 3.0 moles can be added.

In addition, in the step of gelling by heat-treating the polyamic acid solution coated on the carrier, the gelling temperature condition may be 100°C to 250°C.

As the carrier, a glass plate, aluminum foil, a circulating stainless steel belt, a stainless steel drum, or the like can be used.

The treatment time required for gelation may be 5 minutes to 30 minutes, but is not limited thereto, and may vary according to gelation temperature, type of carrier, coating amount of polyamic acid solution, and catalyst mixing conditions.

After separating the gelled film from the carrier, heat treatment is performed to complete drying and imidization.

The heat treatment temperature may be 100°C to 500°C, and the heat treatment time may be 1 minute to 30 minutes. The gelled membrane may be fixed on a fixable support such as a pin-type frame or a clip-type support for heat treatment when heat-treated.

On the other hand, in order to realize an ultra-thin film below 8 μm, when the polyamic acid is coated (discharged) on the carrier in the present invention, process conditions such as discharge volume, speed and pressure should be controlled.

Specifically, the polyamic acid solution should be discharged from the T-Die to the endless belt and the vibration at the time of film-like landing should be minimized, for this reason, when the discharge film is formed, it can be used at a low temperature. Air is supplied under the pressure used when preparing a conventional polyimide film, for example, at a pressure of 10 mmH2O to 40 mmH2O.

Now, the amount discharged from the T-die and the speed of the endless belt can satisfy the following formula, for example, the amount discharged from the T-die can be 150kg/hour to 300kg/hour, and the speed of the endless belt can be 15mpm to 300kg/hour. 25mpm.

[formula]

The amount discharged from the T-die/the time of discharge from the T-die=the specific gravity of the film*(the cross-sectional area of the T-die)*(the speed of the annular belt)

At the laboratory level, ultra-thin thickness polyimide films can be obtained by adjusting the casting thickness, however, in the mass production process, when the stated range is met, ultra-thin thicknesses below 8 μm can be achieved.

Specifically, the polyimide film according to the present invention may have a thickness of 7.5 μm or less, specifically, 3 μm to 7.5 μm, more specifically, 5 μm to 7.5 μm.

Also, when heat treatment is performed by using equipment such as a dryer after being fixed to a pin-shaped frame, in order to prevent the film from cracking during the heat treatment process, it can be lower than the maximum heat treatment when producing a yellow polyimide film of the same thickness. The heat treatment is carried out at a temperature of 50°C to 150°C according to the temperature standard.

In addition, at a temperature of 20° C. to 30° C., the imidized thin film can be thinned by cooling treatment.

The present invention can also provide a coverlay including the polyimide thin film, and an electronic device including the coverlay.

Detailed ways

Hereinafter, the present invention will be described in more detail through specific examples and comparative examples. The following examples are used to illustrate the present invention more specifically, but the present invention is not limited to the following examples.

<Example 1>

Preparation Example 1: Polymerization of Polyamic Acid

As a polyamic acid solution polymerization process, 407.5 g of dimethylformamide (DMF) was added as a solvent in a 1 L reactor under a nitrogen atmosphere.

After setting the temperature to 25° C., add 35.1 g of ODA, 6.3 g of PPD as a diamine monomer, and stir for about 30 minutes. After confirming that the monomer is dissolved, add 51.0 g of PMDA as a dianhydride monomer, and in Add after adjusting the final addition amount so that the final viscosity is 250,000 centipoise to 300,000 centipoise.

After the addition was complete, the temperature was maintained while stirring for 1 hour to polymerize the amic acid solution to a final viscosity of 260,000 centipoise.

Preparation Example 2: Preparation of Black Preparation Solution Containing Barrier Fillers

After the carbon black of 10g, the graphene of 3g are mixed with the DMF of 86g and the dispersant BYK-430 of 1g, utilize grinder to prepare and comprise the carbon black that average particle diameter is 0.5 μ m, the average particle diameter with respect to horizontal direction is A black preparation solution of graphene having a diameter of 10 μm and an average particle diameter of 2 nm in the vertical direction.

Preparation Example 3: Preparation of Polyimide Film

The 20g polyamic acid solution prepared in the preparation example 1 is mixed with the black preparation solution of 4.628g prepared in the preparation example 2, and the isoquinoline (IQ) of 0.65g, the acetic anhydride (AA) of 4.78g, and 0.57g of DMF as a catalyst, uniformly mixed, using a scraper to flow on a stainless steel (SUS) plate (100SA, produced by Sweden Sandvik (Sandvik) company) to 70 μm, and then within the temperature range of 100 ° C to 200 ° C to dry.

Then, the film was peeled from the SUS sheet and fixed on a pin-type frame, and then transferred to a high-temperature tenter.

The film was heated from 200°C to 600°C on a high-temperature tenter, cooled at a temperature of 25°C, and then separated from the pin frame to prepare a polyimide resin containing 100 parts by weight, 3 parts by weight A 7.5 μm thick polyimide film with carbon black as the first barrier filler and 1 part by weight of graphene as the second barrier filler.

<Example 2>

Except mixing the carbon black of 3.5g, the graphene of 0.5g in preparation example 2, make the polyimide resin of 100 parts by weight be a benchmark, comprise the carbon black of 3.5 parts by weight and the graphene of 0.5 parts by weight , A polyimide film was prepared in the same manner as in Example 1.

<Example 3>

In addition to mixing the carbon black of 3.7g and the graphene of 0.3g in Preparation Example 2, so that it is based on the polyimide resin of 100 parts by weight, the carbon black of 3.7 parts by weight and the graphene of 0.3 parts by weight are included , A polyimide film was prepared in the same manner as in Example 1.

<Example 4>

In addition to mixing the carbon black of 5g and the graphene of 1g in Preparation Example 2 so that it is based on the polyimide resin of 100 parts by weight, except that the carbon black of 5 parts by weight and the graphene of 1 part by weight are included, A polyimide film was prepared in the same manner as in Example 1.

<Example 5>

Except that the carbon black of 1g, the graphene of 0.3g are mixed in Preparation Example 2, so that the polyimide resin of 100 parts by weight is used as a benchmark, and the carbon black of 1 weight part and the graphene of 0.3 parts by weight are included, A polyimide film was prepared in the same manner as in Example 1.

<Example 6>

In preparation example 2, carbon black with an average particle size of 1 μm is used instead of carbon black with an average particle size of 0.5 μm, and graphite with an average particle size of 15 μm relative to the horizontal direction and 2 nm relative to the vertical direction. A polyimide film was prepared in the same manner as in Example 1, except that graphene having an average particle diameter in the horizontal direction of 10 μm and an average particle diameter in the vertical direction of 2 nm was mixed.

<Example 7>

In Preparation Example 2, the carbon black with an average particle diameter of 0.1 μm is used instead of the carbon black with an average particle diameter of 0.5 μm, and the average particle diameter with respect to the horizontal direction is 5 μm, and the average particle diameter with respect to the vertical direction is 2 nm. Graphene was mixed instead of graphene having an average particle diameter of 10 μm in the horizontal direction and 2 nm in the vertical direction, and a polyimide film was prepared in the same manner as in Example 1. .

<Comparative example 1>

A polyimide film was prepared in the same manner as in Example 1, except that 4 g of carbon black was separately mixed in Preparation Example 2 so that the polyimide film contained 4 parts by weight of carbon black.

<Comparative example 2>

Except in preparation example 2 with the carbon black of 2g, the graphene of 2g is mixed, so that polyimide film comprises the carbon black of 2 weight parts and the graphene of 2 weight parts, with the method identical with embodiment 1 Polyimide films were prepared.

<Comparative example 3>

Except in preparation example 2 with the carbon black of 1g, the graphene of 3g is mixed, so that polyimide film comprises the carbon black of 1 weight part and the graphene of 3 weight parts, with the method identical with embodiment 1 Polyimide films were prepared.

<Comparative example 4>

In addition to the carbon black of 3.9g in preparation example 2, the graphene of 0.1g is mixed, so that polyimide film comprises the carbon black of 3.9 parts by weight and the graphene of 0.1 part by weight, with the same as embodiment 1 The polyimide film was prepared by the method.

<Comparative example 5>

In addition to the carbon black of 0.5g in preparation example 2, the graphene of 3.5g is mixed, so that polyimide film comprises the carbon black of 0.5 weight part and the graphene of 3.5 weight parts, with embodiment 1 identical The polyimide film was prepared by the method.

<Comparative example 6>

Except in preparation example 2 with the carbon black of 8g, the graphene of 1g is mixed, so that polyimide film comprises the carbon black of 8 weight parts and the graphene of 1 weight part, with the method identical with embodiment 1 Polyimide films were prepared.

<Comparative example 7>

In addition to the carbon black of 0.5g in preparation example 2, the graphene of 0.1g is mixed, so that polyimide film comprises the carbon black of 0.5 weight part and the graphene of 0.1 weight part, with embodiment 1 identical The polyimide film was prepared by the method.

<Comparative example 8>

In Preparation Example 2, carbon black with an average particle size of 2 μm is used instead of carbon black with an average particle size of 0.5 μm, and graphite with an average particle size of 20 μm relative to the horizontal direction and 2 nm relative to the vertical direction. A polyimide film was prepared in the same manner as in Example 1, except that graphene having an average particle diameter in the horizontal direction of 10 μm and an average particle diameter in the vertical direction of 2 nm was mixed.

<Comparative example 9>

In Preparation Example 2, the carbon black with an average particle diameter of 0.01 μm is used instead of the carbon black with an average particle diameter of 0.5 μm, and the average particle diameter with respect to the horizontal direction is 3 μm and the average particle diameter with respect to the vertical direction is 2 nm. Graphene was mixed instead of graphene having an average particle diameter of 10 μm in the horizontal direction and a graphene having an average particle diameter of 2 nm in the vertical direction, and a polyimide film was prepared in the same manner as in Example 1. .

Experimental example 1: evaluation of light transmittance

For the polyimide films prepared respectively in <Example 1> to <Example 7> and <Comparative Example 1> to <Comparative Example 9>, using transmittance measuring equipment, (model: ColorQuesetXE, manufacturer: U.S. The transmittance was measured by ASTM D1003 in the visible region by HunterLab, and the results are shown in Table 1 below.

Table 1

Referring to Table 1, in the case of the polyimide films of Examples 1 to 7, including 1 to 5 parts by weight of the first barrier filler, the average particle size is 0.1 μm to 1 μm and 0.3 parts by weight to 1 part by weight of the second shielding filler has an average particle diameter of 5 μm to 15 μm in the horizontal direction, and an average particle diameter of 1 nm to 10 nm in the vertical direction. The light transmittance of Comparative Example 1 is relatively low.

And, can confirm, comparative example 4, the polyimide film of 5 and comparative example 7 to 9, with respect to embodiment 1 to embodiment 7, light transmittance is very high, shows that according to the barrier of the polyimide film of the present invention Relatively excellent.

From these results, it can be known that, as shown in Comparative Examples 4, 5 and Comparative Examples 7 to 9, when the content of the first barrier filler and/or the second barrier filler exceeds the scope of the present invention, or the first barrier filler When the particle size of the polyimide film and the particle diameter of the second shielding filler exceed the scope of the present invention, the shielding performance of the polyimide film is obviously reduced.

Experimental Example 2: Elastic Modulus Evaluation

For the polyimide films prepared respectively in <Example 1> to <Example 7> and <Comparative Example 1> to <Comparative Example 9>, use the Instron 5564 model to measure the MD direction and TD with the ASTM D 882 method Directional moduli, the results of which are shown in Table 2 below.

Table 2

Referring to Table 2, in the case of the polyimide films of Examples 1 to 7, including: 1 to 5 parts by weight of a first barrier filler with an average particle size of 0.1 to 1 μm and 0.3 parts by weight To 1 part by weight of the second barrier filler, the average particle diameter relative to the horizontal direction is 5 μm to 15 μm, and the average particle diameter relative to the vertical direction is 1 nm to 10 nm, so that it can be confirmed that the second barrier filler does not contain Unlike Comparative Example 1, the modulus measured in the MD direction was 3 GPa or more.

And, it can be confirmed that the modulus of the polyimide films of Comparative Example 4 and Comparative Examples 7 to 9 in the MD direction is less than 3 GPa, which is lower than that of Examples 1 to 7, which can indicate that the polyimide films according to the present invention The mechanical stability of the amine film is relatively excellent.

From these results, it can be known that, as in Comparative Example 4 and Comparative Examples 7 to 9, when the content of the first shielding filler and/or the second shielding filler exceeds the scope of the present invention, or the first shielding filler and the second shielding filler When the particle size of the permanent filler exceeds the scope of the present invention, the mechanical stability of the polyimide film is obviously reduced.

Experimental Example 3: Evaluation of Dielectric Constant

With respect to <embodiment 1> to <embodiment 7> and <comparative example 1> to the polyimide film prepared respectively in <comparative example 9>, utilize the SPDR measuring instrument of Keysight company to measure the dielectric under 1.1GHz frequency constant, the results are shown in Table 3 below.

Referring to Table 3, in the case of the polyimide films of Examples 1 to 7, it can be confirmed that, with respect to Comparative Examples 2, 3 and 5 in which the content of the second barrier filler exceeds the content range according to the present invention, The dielectric constant is relatively low, and the insulation of the finally prepared polyimide film is relatively excellent.

Therefore, it can be confirmed in Tables 1 to 3 that, for these comparative examples, at least one of the physical properties of shielding, mechanical stability, and insulation does not satisfy the scope of the present invention. On the contrary, these examples are all The physical properties are met.

Although the above has been described in detail with reference to the embodiments of the present invention, those skilled in the art to which the present invention pertains can make various applications and modifications within the scope of the present invention based on the above-mentioned contents.

industrial availability

As mentioned above, the object of the present invention is to provide a black polyimide film, specifically, configured to include 1 to 5 parts by weight of the first barrier filler and 0.3 parts by weight in the polyimide film To 1 part by weight of the second shielding filler, so that even a small amount of the filler can reduce light transmittance to improve shielding, improve modulus to ensure mechanical stability, and can minimize the dielectric constant.

Claims (9)

1. A polyimide film, comprising:

100 parts by weight of a polyimide resin;

1 to 5 parts by weight of a first shielding filler having an average particle diameter of 0.1 to 1 μm; and

0.3 to 1 part by weight of a second shielding filler having an average particle diameter of 5 to 15 μm with respect to a horizontal direction and an average particle diameter of 1 to 10nm with respect to a vertical direction,

a light transmittance in a visible light region of 7% or less, a modulus of the polyimide film measured in the longitudinal direction and/or the transverse direction of 3GPa or more, a thickness of the polyimide film of 8.0 [ mu ] m or less,

the first shielding filler is carbon black,

the second shielding filler is graphene.

2. The polyimide film according to claim 1, wherein the first shielding filler has a sphericity of 0.8 or more.

3. The polyimide film according to claim 1, wherein a ratio of a content of the second shielding filler to a content of the first shielding filler is 100% to 1600%.

4. The polyimide film according to claim 1, wherein the polyimide film has a modulus of 3GPa or more as measured in the longitudinal direction.

5. The polyimide film according to claim 1, wherein the polyimide film has a dielectric constant of 5 or less as measured at a frequency of 1.1 Ghz.

6. The polyimide film according to claim 1, wherein the thickness of the polyimide film is 3 μm to 7.5 μm.

7. A method for producing a polyimide film according to claim 1, comprising:

step (a) of polymerizing polyamic acid from dianhydride and diamine;

a step (b) of preparing a first shielding filler having an average particle diameter of 0.1 to 1 μm and a second shielding filler having an average particle diameter of 5 to 15 μm with respect to a horizontal direction and an average particle diameter of 1 to 10nm with respect to a vertical direction by using a grinder; and

and (c) mixing the first shielding filler and the second shielding filler with the polyamic acid, forming a film on a support, and performing heat treatment to perform imidization.

8. A coverlay film comprising the polyimide film according to claim 1.

9. An electronic device comprising the cover film according to claim 8.