JP7367214B2 - Polyimide film manufacturing method and polyimide film manufactured thereby - Google Patents

Description

The present invention relates to a method for producing a polyimide film and a polyimide film produced thereby. More specifically, the present invention relates to a method for producing a polyimide film having a low elastic modulus, high yield point and yield strength, high transmittance and low haze, and the polyimide film produced thereby.

Flexible displays, such as curved, bendable, foldable, rollable, etc., are the next generation of displays that have recently received interest from both academia and industry. Among the various types of materials that make up flexible displays, functional film/coating materials are important polymer substrate materials that make up flexible displays, and are essential for the successful realization and development of flexible displays. Polyimide is attracting attention as a core material.

Polyimide is a polymer characterized by having a heteroimide ring in its main chain.In addition to its excellent heat resistance, polyimide has excellent mechanical properties, flame retardancy, chemical resistance, and low dielectric constant, and is used as a coating material, It is applied to a wide range of applications such as molding materials and composite materials.

The most important physical property required of polymer substrates for flexible displays is flexibility. In particular, such a polymer substrate must not only not be damaged during the carving, bending, folding, rolling, and stretching processes in which flexible displays are repeatedly deformed, but also must not lose various initial physical properties.

On the other hand, polymer substrates for flexible displays are required to be transparent for various purposes, and for this reason, they often have optical properties such as high light transmittance and low haze. be requested.

The object of the present invention is to provide a method for producing polyimide films with low elastic modulus and high yield point and yield strength.

Another object of the present invention is to provide a method for producing a polyimide film with high transmittance and low haze.

Still another object of the present invention is to provide a polyimide film produced by the above-described polyimide film production method.

1. According to one aspect, a step of producing a polyamic acid by reacting a dianhydride monomer and a diamine monomer; and a polyimide precursor solution including the polyamic acid, an imidization catalyst, a dehydrating agent, a filler, and a solvent. and a step of producing a polyimide film by imidizing the polyamic acid, wherein the imidization catalyst is used in an amount per mole of amic acid groups in the polyamic acid. The dehydrating agent is contained in a molar ratio of about 0.8 mol to about 2.5 mol, and the dehydrating agent is contained in a molar ratio of about 2.0 mol to about 4.0 mol per 1 mol of amic acid groups in the polyamic acid. The average particle size (D ₅₀ ) of the filler is about 1.6 μm or less, and the polyimide film has a modulus of about 2.5 GPa to about 4.0 GPa. be done.

2. In the first embodiment, biphenyltetracarboxylic dianhydride (BPDA) is included in an amount of about 10 mol % to about 90 mol % based on the total molar amount of dianhydride monomers.

3. In the first or second embodiment, pyromellitic dianhydride (PMDA) is further included in an amount of about 10 mol % to about 90 mol % based on the total molar amount of dianhydride monomers.

4. In any one of the first to third embodiments, the diamine monomer is m-tolidine (m-TD), 4,4'-oxydianiline (ODA), 1,3-bis(4 -aminophenoxy)benzene (TPE-R), 2,2-bis(4-[4-aminophenoxy]-phenyl)propane (BAPP), or combinations thereof.

5. According to another aspect, there is provided a polyimide film produced by the production method described in any one of the first to fourth embodiments.

6. In the fifth embodiment, the polyimide film may have a yield point of about 2.3% to about 2.8%.

7. In the fifth or sixth embodiment, the polyimide film may have a yield strength of about 55 MPa to about 80 MPa.

8. In any one of the fifth to seventh embodiments, the polyimide film may have a transmittance of about 43% or more in the visible light region.

9. In any one of the fifth to eighth embodiments, the polyimide film may have a haze of about 7.5% or less.

The present invention is effective in providing a method for producing a polyimide film having a low elastic modulus, high yield point and yield strength, high transmittance and low haze, and a polyimide film produced therefrom.

In describing the present invention, if it is determined that detailed description of such known techniques may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

When "including", "having", "becoming", etc. mentioned in this specification are used, other parts can be added as long as "only" is not used. When a component is expressed in the singular, it also includes the plural unless there is an explicit statement.

In addition, when interpreting the constituent elements, they shall be interpreted to include a margin of error even if there is no other explicit statement.

In this specification, "~" in "a to b" indicating a numerical range is defined as ≧a and ≦b.

The inventor of the present invention discovered that when producing a polyimide film from polyamic acid, the content of the imidization catalyst and dehydrating agent and the average particle diameter (D ₅₀ ) of the filler were controlled to produce a polyimide film of about 2. We have demonstrated that it is possible to produce a polyimide film that has a high yield point and yield strength even with a low modulus of 0 GPa to about 4.0 GPa, has a low degree of damage even after repeated deformation, and has high transmittance and low haze. This discovery led to the completion of the present invention. The present invention will be explained in more detail below.

Method for manufacturing a polyimide film According to one aspect, a method for manufacturing a polyimide film is provided. The method for producing a polyimide film includes the steps of producing a polyamic acid by reacting a dianhydride monomer and a diamine monomer, and a polyimide precursor containing the polyamic acid, an imidization catalyst, a dehydrating agent, a filler, and a solvent. the step of producing a body solution, and the step of producing a polyimide film by imidizing the polyamic acid, wherein the imidization catalyst is about 0.8 mol per mol of amic acid group in the polyamic acid. The dehydrating agent is contained in a molar ratio of about 2.0 mol to about 4.0 mol per 1 mol of amic acid groups in the polyamic acid, and the dehydrating agent is contained in a molar ratio of about 2.0 mol to about 4.0 mol, The filler may have an average particle size (D ₅₀ ) of about 1.6 μm or less, and the polyimide film may have a modulus of about 2.5 GPa to about 4.0 GPa. Each step will be explained in more detail below.

First, a polyamic acid can be produced by reacting a dianhydride monomer and a diamine monomer. More specifically, a dianhydride monomer and a diamine monomer can be polymerized in a solvent to produce a polyamic acid solution. At this time, all the monomers may be added at once, or each monomer may be added sequentially, and in this case, partial polymerization between the monomers may occur.

The type of dianhydride monomer is not particularly limited, and can be selected from a wide variety within a range that does not adversely affect the effects of the present invention. For example, dianhydride monomers can include biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), and the like, which can be used alone or in combination.

According to one embodiment, the dianhydride monomer is about 10 mol% to about 90 mol% (e.g., 10 mol%, 15 mol%, 20 mol%) based on the total molar amount of dianhydride monomers. %, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol%, 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, or 90 mol%) of biphenyltetracarboxylic dianhydride (BPDA). In this case, it is possible to produce polyimide films with high yield point and yield strength at low elastic modulus, high transmittance and low haze. For example, the dianhydride monomer may be about 15 mole % to about 85 mole %, based on the total molar amount of dianhydride monomers, as another example about 20 mole % to about 80 mole %, and even other Examples include, but are not limited to, about 30 mol% to about 70 mol%.

According to one embodiment, the dianhydride monomers can include biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA). In this case, it is possible to produce polyimide films with high yield point and yield strength at low elastic modulus, high transmittance and low haze. Biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) may be mixed, for example, in a ratio of about 10:90 to about 90:10 (e.g., 10:90, 15:85, 20:80, 25: 75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, or 90:10), other examples include, but are not limited to, molar ratios of about 20:80 to about 80:20, and yet other examples of molar ratios of about 30:70 to about 70:30. . According to one embodiment, the dianhydride monomers exceed about 10 mole percent of biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, based on the total molar amount of dianhydride monomers. About 100 mol% (e.g., 11 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, 55 mol%, 60 mol% , 65 mol%, 70 mol%, 75 mol%, 80 mol%, 85 mol%, 90 mol%, 95 mol%, or 100 mol%), but are not limited to It's not a thing.

The type of diamine monomer is not particularly limited, and can be selected from a variety of types within a range that does not adversely affect the effects of the present invention. For example, diamine monomers include m-tolidine (m-TD), 4,4'-oxydianiline (ODA), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 2,2 -bis(4-[4-aminophenoxy]-phenyl)propane (BAPP), etc., and these can be used alone or in combination of two or more. According to one embodiment, the diamine monomer can include m-tolidine (m-TD) or 4,4'-oxydianiline (ODA). According to other embodiments, the diamine monomer comprises m-tolidine (m-TD) and 4,4'-oxydianiline (ODA) in a range of about 1:99 to about 99:1 (e.g., 1:99 , 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65 :35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5 or 99:1), for example from about 1:99 to about 50:50, for other examples about 1 :99 to about 30:70, and further examples include, but are not limited to, about 5:95 to about 20:80.

The organic solvent is not particularly limited as long as it can dissolve polyamic acid, and may be, for example, an aprotic polar organic solvent. Non-limiting examples of aprotic polar organic solvents include amide solvents such as N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), p-chlorophenol, o-chlorophenol. Examples include phenolic solvents such as N-methylpyrrolidone (NMP), gamma-butyrolactone (GBL), and Diglyme, which can be used alone or in combination of two or more. Optionally, auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol, water, etc. may be used to adjust the solubility of the polyamic acid. In one embodiment, the organic solvent may be an amide solvent, such as, but not limited to, N,N-dimethylformamide or N,N-dimethylacetamide.

According to one embodiment, the polyamic acid is about 5% to about 35% by weight (e.g., 5%, 10%, 15%, 20%, 25% by weight, based on the total weight of the polyamic acid solution). %, 30%, or 35% by weight). Within the above range, the polyamic acid solution may have a molecular weight and solution viscosity suitable for forming a film. Based on the total weight of the polyamic acid solution, the polyamic acid may include, for example, from about 10% to about 30% by weight, and in other examples from about 15% to about 25% by weight, but is not limited thereto. do not have.

Thereafter, a polyimide precursor solution containing a polyamic acid, an imidization catalyst, a dehydrating agent, a filler, and a solvent can be produced. More specifically, the polyimide precursor solution can be prepared by adding an imidization catalyst, a dehydrating agent, a filler, and optionally an additional solvent to the polyamic acid solution. The additional solvent can be understood with reference to the explanation regarding the solvent used during the production of the polyamic acid solution.

The imidization catalyst can mean a component that has the effect of promoting the ring-closing reaction of polyamic acid, and examples thereof include tertiary amine compounds, more specifically, aliphatic tertiary amines, aromatic tertiary amines, and aromatic tertiary amines. amines, heterocyclic tertiary amines, and the like. Among them, heterocyclic tertiary amines can be used from the viewpoint of reactivity as a catalyst, and examples thereof include quinoline, isoquinoline, β-picoline, and pyridine, and these can be used alone or in combination. Can be used in combination.

The imidization catalyst is used in a molar ratio of about 0.8 mol to about 2.5 mol (for example, 0.8 mol, 0.9 mol, 1.0 mol, 1 mol) per 1 mol of amic acid groups in the polyamic acid. .1 mol, 1.2 mol, 1.3 mol, 1.4 mol, 1.5 mol, 1.6 mol, 1.7 mol, 1.8 mol, 1.9 mol, 2.0 mol, 2 .1 mole, 2.2 mole, 2.3 mole, 2.4 mole, or 2.5 mole molar ratio). When the content of the imidization catalyst is below the above range, it is difficult to form a film, and when the content of the imidization catalyst is above the above range, the modulus becomes excessively large (for example, exceeding about 4.0 GPa), There is a problem of low transmittance. Therefore, in the above range, it is possible to produce a polyimide film with a low elastic modulus, high yield point and yield strength, high transmittance and low haze. For example, the imidization catalyst is contained in a molar ratio of about 0.8 mol to about 2.4 mol per 1 mol of amic acid groups in the polyamic acid, but is not limited thereto.

The dehydrating agent can mean an agent that promotes the ring-closing reaction by dehydrating polyamic acid, and includes, for example, aliphatic acid anhydrides, aromatic acid anhydrides, N,N'-dialkylcarbodiimides, lower aliphatic halogens, etc. halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, thionyl halides, etc., and these can be used alone or in combination of two or more. Among these, aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and lactic anhydride can be used alone or in combination of two or more from the viewpoint of availability and cost.

The dehydrating agent is used in a molar ratio of about 2.0 mol to about 4.0 mol (for example, 2.0 mol, 2.1 mol, 2.2 mol, 2.0 mol) per 1 mol of amic acid groups in the polyamic acid. 3 mol, 2.4 mol, 2.5 mol, 2.6 mol, 2.7 mol, 2.8 mol, 2.9 mol, 3.0 mol, 3.1 mol, 3.2 mol, 3. 3 mol, 3.4 mol, 3.5 mol, 3.6 mol, 3.7 mol, 3.8 mol, 3.9 mol, or 4.0 mol). In this range, it is possible to produce polyimide films with low elastic modulus, high yield point and yield strength, high transmittance and low haze. For example, the dehydrating agent is included in a molar ratio of about 2.5 mol to about 3.3 mol per 1 mol of amic acid groups in the polyamic acid, but is not limited thereto.

According to one embodiment, the molar ratio of imidization catalyst to dehydrating agent (imidization catalyst: dehydrating agent) is from about 1:1 to about 1:10 (e.g., 1:1, 1:1.1, 1: 1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10). In this range, it is possible to produce polyimide films with low elastic modulus, high yield point and yield strength, high transmittance and low haze. For example, the molar ratio of imidization catalyst to dehydrating agent is about 1:1.2 to about 1:6, in other examples about 1:1.3 to about 1:5, and in still other examples about 1:1. The ratio may be from .3 to about 1:4, but is not limited thereto.

Fillers can impart roughness to polyimide films, and examples thereof include inorganic fillers, more specifically, dibasic calcium phosphate, barium sulfate, calcium carbonate, spherical silica, etc. It can be used alone or in combination of two or more.

The filler can have an average particle size (D ₅₀ ) of about 1.6 μm or less, specifically greater than 0 μm to about 1.6 μm. In this range, it is possible to produce polyimide films with low elastic modulus, high yield point and yield strength, high transmittance and low haze. For example, the average particle diameter (D ₅₀ ) of the filler is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm. , 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, or 1.6 μm, other examples include, but are not limited to, about 0.5 μm to about 1.6 μm. It's not something you can do.

The filler content is not particularly limited, but is about 0.05% by weight to about 0.5% by weight (for example, 0.05% by weight, 0.1% by weight, 0.15% by weight, based on the total weight of the polyimide film). (wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, or 0.5 wt%); In the range, it is possible to produce polyimide films with high yield point and yield strength at low elastic modulus, high transmittance and low haze. For example, the filler content may be about 0.1% to about 0.3% by weight, but is not limited thereto.

In one embodiment, the polyimide precursor solution may contain various additives within a range that does not adversely affect the effects of the present invention. Examples of such additives include antioxidants, light stabilizers, antistatic agents, heat stabilizers, flame retardants, etc., and these can be used alone or in combination of two or more.

Thereafter, the polyamic acid can be imidized to produce a polyimide film. For example, a polyimide film can be produced by casting a polyimide precursor solution on a support, drying it to produce a gel film, and heat-treating the gel film to imidize it.

According to one embodiment, the step for forming a gel film includes a polyimide precursor solution cast on a support (e.g., glass plate, aluminum foil, endless stainless steel belt, stainless steel drum, etc.) for about 400 ml of polyimide precursor solution. The gel film is dried at a temperature ranging from 100°C to about 300°C, for example from about 80°C to about 200°C, in another example from about 100°C to about 180°C, and in still another example from about 100°C to about 130°C. Obtainable. This causes partial curing and/or drying to form a gel film. The gel film is an intermediate step in the curing of polyamic acid to polyimide and can be self-supporting.

In some cases, a step of stretching the gel film may be included in order to adjust the thickness and size of the final polyimide film and improve orientation, and the stretching may be performed in the machine transport direction (MD). and in at least one of the transverse direction (TD) with respect to the machine transport direction.

The volatile content of the gel film may be, but is not limited to, about 5% to about 500% by weight, such as about 5% to about 200% by weight, and other examples from about 5% to about 200% by weight. The amount may be 150% by weight, and within the above range, it is effective to avoid defects such as film breakage, color staining, and property fluctuation during the process of heat treatment to obtain a polyimide film later. Here, the volatile content of the gel film can be calculated using the following formula 2, where A is the weight of the gel film and B is the weight after heating the gel film at 450°C for 20 minutes. means.

<Formula 1>
(A-B)*100/B

According to one embodiment, the step of heat treating the gel film includes heating the gel film at a temperature in the range of about 50°C to about 700°C, such as about 150°C to about 600°C, and other examples, about 200°C to about 600°C. A polyimide film can be obtained by heat-treating at a variable temperature to remove solvents remaining in the gel film and imidizing most of the remaining amic acid groups.

In some cases, the polyimide film obtained as described above may be heat-finished at a temperature of about 400° C. to about 650° C. for about 5 seconds to about 400 seconds to further cure the polyimide film, or the polyimide film obtained as described above may be further cured. This may be done under a certain tension in order to relieve any internal stresses that may remain in the film.

Polyimide film According to another aspect, a polyimide film manufactured by the above-described manufacturing method is provided. The polyimide film produced by the above-mentioned production method has a low elastic modulus, a high yield point, and a high transmittance.

The polyimide film has a pressure of about 2.5 to about 4.0 GPa (for example, 2.5 GPa, 2.6 GPa, 2.7 GPa, 2.8 GPa, 2.9 GPa, 3 GPa, 3.1 GPa, 3.2 GPa, 3.3 GPa, 3.4 GPa, 3.5 GPa, 3.6 GPa, 3.7 GPa, 3.8 GPa, 3.9 GPa, or 4 GPa). According to one embodiment, the modulus of the polyimide film may be from about 2.7 GPa to about 3.7 GPa, but is not limited thereto.

According to one embodiment, the polyimide film is about 2.3% to about 2.8% (e.g., 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, or 2.8%). For example, the polyimide film may have a yield point of about 2.4% to about 2.7%, but is not limited thereto.

According to one embodiment, the polyimide film has a pressure of about 55 MPa to about 80 MPa (e.g., 55 MPa, 56 MPa, 57 MPa, 58 MPa, 59 MPa, 60 MPa, 61 MPa, 62 MPa, 63 MPa, 64 MPa, 65 MPa, 66 MPa, 67 MPa, 68 MPa, 69 MPa, 70 MPa). Pa , 71 MPa, 72 MPa, 73 MPa, 74 MPa, 75 MPa, 76 MPa, 77 MPa, 78 MPa, 79 MPa, or 80 MPa). For example, the yield strength of the polyimide film may be, but is not limited to, about 55 MPa to about 75 MPa, as another example, about 60 MPa to about 80 MPa, and still another example, about 60 MPa to about 75 MPa. .

According to one embodiment, the polyimide film can have a transmittance of about 43% or more (eg, about 43% to about 100%) in the visible light region, eg, wavelengths from about 380 nm to about 780 nm. For example, the transparency of the polyimide film may be from about 43% to about 90%, and as another example, from about 45% to about 80%, but is not limited thereto.

According to one embodiment, the polyimide film can have a thickness of about 5 μm to about 100 μm. The thickness of the polyimide film may be, for example, but not limited to, about 10 μm to about 80 μm, another example about 20 μm to about 70 μm, and still another example about 25 μm to about 60 μm. .

Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and is not to be construed as limiting the present invention in any way.

Example 1
In 326 g of dimethylformamide (DMF), 17 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 23 g of pyromellitic dianhydride as dianhydride monomers, and diamine monomer. 4 g of m-tolidine (m-TD) and 30 g of 4,4'-oxydianiline (ODA) were mixed and polymerized to produce a polyamic acid solution with a solid content of 18.5% by weight. .

To the thus produced polyamic acid solution, 1.0 molar ratio of isoquinoline as an imidization catalyst and 2.5 molar ratio of acetic anhydride as a dehydrating agent were added per mole of amic acid group, and the total amount of polyimide film was Dibasic calcium phosphate (D ₅₀ =1.5 μm) was added as a filler so that the amount was 0.2% by weight based on the weight, and 57 g of DMF was added to prepare a polyimide precursor solution.

The polyimide precursor solution was cast onto a SUS plate (100SA, Sandvik) using a doctor blade, and dried at 110° C. for 10 minutes to prepare a gel film. After the gel film was separated from the SUS plate, it was heat-treated at 400° C. for 10 minutes to produce a polyimide film having a thickness of 50 μm.

Examples 2 to 6 and Comparative Examples 1 to 6
A polyimide film was produced using the same method as in Example 1, except that the content of the imidization catalyst, the dehydrating agent, and the average particle size of the filler were changed as shown in Table 1.

However, in the case of Comparative Examples 4 and 5, it was impossible to form a polyimide film.

Physical property evaluation method (1) Modulus (unit: GPa), yield point (unit: %), yield strength (unit: Mpa): The produced polyimide film was cut into 15 mm x 50 mm to produce a test piece, and the test pieces were tested according to ASTM D882 standards. Based on this, the modulus, yield point, and yield strength were measured at room temperature using a tensile tester (Instron 5564, Instron) at a tensile speed of 200 mm/min, and the results are shown in Table 1 below. .

(2) Transmittance (unit: %), haze (unit: %): Based on the ASTM D1003 standard, transmittance and haze values were measured at room temperature using a haze meter (HM-150, MURAKAMI), and the results were are shown in Table 1 below.

As can be confirmed from Table 1, in Examples 1 to 6, where the imidization catalyst content, dehydrating agent content, and filler average particle size are within the range of the present invention, the modulus of the polyimide film is low and It is found that it has a high yield point, high transmittance and low haze.

On the other hand, in Comparative Examples 1 and 2 in which the average particle diameter of the filler deviates from the range of the present invention, the haze of the polyimide film was as high as 9.2% or more. In the case of Comparative Example 3, in which the content of the imidization catalyst exceeds the range of the present invention, the modulus of the polyimide film is high at 4.1 GPa, the permeability is low at 40% or less, and the content of the imidization catalyst is within the range of the present invention. In the case of Comparative Example 4, which did not reach this level, it was impossible to form a film. In the case of Comparative Example 5, in which the content of the dehydrating agent is outside the scope of the present invention, it is impossible to form a film, and in the case of Comparative Example 6, in which the content of the dehydrating agent is outside the scope of the present invention, the permeability was low.

Simple variations and modifications of the present invention can be readily effected by those skilled in the art, and all such variations and modifications are within the scope of the present invention.

Claims (6)

producing a polyamic acid by reacting a dianhydride monomer and a diamine monomer;
producing a polyimide precursor solution containing the polyamic acid, an imidization catalyst, a dehydrating agent, a filler, and a solvent;
A method for producing a polyimide film, the method comprising: producing a polyimide film by imidizing the polyamic acid,
The dianhydride monomer includes biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA),
The proportion of the biphenyltetracarboxylic dianhydride (BPDA) is 10 mol% to 90 mol% based on the total molar amount of the dianhydride monomers,
The proportion of the pyromellitic dianhydride (PMDA) is 10 mol% to 90 mol% based on the total molar amount of the dianhydride monomer,
The diamine monomer includes m-tolidine (m-TD),
The amount of the imidization catalyst is 0.00% per mole of the amic acid group in the polyamic acid. 8 moles to 2 . Contained in a molar ratio of 5 moles,
The amount of the dehydrating agent is 2.0% per mole of the amic acid group in the polyamic acid. 0 mole to 4 . Contained in a molar ratio of 0 mol,
The average particle diameter (D ₅₀ ) of the filler is 1 . 6 μm or less,
The modulus of the polyimide film is 2 . 5GPa ~4 . A method for producing a polyimide film having a pressure of 0 GPa. The diamine monomer further includes 4,4'-oxydianiline (ODA), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 2,2-bis(4-[4-amino The method for producing a polyimide film according to claim 1 , comprising phenoxy]-phenyl)propane (BAPP), or a combination thereof. A polyimide film produced by the production method according to claim 1 or 2 ,
The polyimide film has a transmittance in the visible light range of 43% or more and 80% or less . The polyimide film has a yield point of 2 . 3% ~2 . 4. The polyimide film according to claim 3 , wherein the polyimide film has a content of 8%. The polyimide film according to claim 3 or 4 , wherein the polyimide film has a yield strength of 55 MPa to 80 MPa. The polyimide film has a haze of 7 . The polyimide film according to any one of claims 3 to 5 , which has a content of 5% or less.