JP2022516281A - A method for producing a polyamic acid composition, a polyamic acid composition, a method for producing a polyimide film using the same, and a polyimide film produced by the method for producing the same. - Google Patents

Abstract

The present invention relates to a method for producing a polyamic acid composition, a polyamic acid composition, a method for producing a polyimide film using the same, and a polyimide film produced by the method for producing the same, and more specifically, a hetero atom and a halogen atom are used. It is produced by a method for producing a polyamic acid composition containing the introduced diamine compound and acid dianhydride compound and capable of improving optical properties, a polyamic acid composition, a method for producing a polyimide film using the same, and a method for producing the same. Regarding polyimide film.

Description

The present invention relates to a method for producing a polyamic acid composition, a polyamic acid composition, a method for producing a polyimide film using the same, and a polyimide film produced by the method for producing the polyimide film, more specifically, a hetero atom. A method for producing a polyamic acid composition capable of improving optical properties by containing a diamine compound into which a halogen atom has been introduced and an acid dianhydride compound, a polyamic acid composition, a method for producing a polyimide film using the same, and a method thereof. The present invention relates to a polyimide film manufactured by a manufacturing method.

The substrate material of a flexible display, which is attracting attention as a next-generation display device, is required to be light, not torn, flexible, and have no form restrictions due to easy processability. In addition to being lighter than the glass substrate currently used as a display substrate material, polymer materials that are not torn, are easy to manufacture, and can produce thin film films are attracting attention as the optimum material for realizing flexible displays. Has been done.

Conventionally, a flexible device generally uses an organic light emitting diode (OLED) display and uses a TFT process at a high process temperature (300 to 500 ° C.). Polymer materials that can withstand such high process temperatures are extremely limited. For this reason, recently, as a candidate for a plastic substrate for a transparent flexible display, the use of a polyimide resin having excellent heat resistance and dimensional stability is increasing.

In addition, due to the continuous development of organic light emitting diode technology, it will have a broad portfolio of flexible tablet PCs, wearable devices, etc., and is positioned as a next-generation display. At the same time, it is expanding its application to lighting due to its unique and excellent color quality of white light. In the field of lighting applications, there is increasing interest in polymer resins having excellent optical characteristics and high refractive index in order to reproduce the realization of a highly efficient light source by efficient light extraction.

On the other hand, in many cases, a polymer substrate material having a high refractive index (n = 1.7 or more) is required for use in organic light emitting diode lighting applications. The difference in the refractive index between the light source and the polymer capsule material induces total internal reflection when light passes through the light source and passes through the capsule material at a specific incident angle, which reduces the light extraction efficiency of the device. In particular, excellent optical characteristics and a high refractive index are required for application to advanced optical equipment, but since ordinary polyimide has a low refractive index in the range of about 1.3 to 1.6, There is a problem that the light extraction efficiency is lowered.

Korean Registered Patent No. 10-1704010 relates to a diamine compound having an aromatic ring substituent containing a hetero atom and a halogen atom introduced therein, and the polyamic acid and polyimide produced thereby, and has a high refractive index and a low refractive index. Although a transparent film having a double refractive index is provided, there is a limit in providing a film having an improved heat resistance and morphological stability while satisfying a high refractive index of 1.7 or more. there were.

Challenges to solve the challenges

The present invention is for solving the above-mentioned problems, and a specific object thereof is as follows.

In the present invention, a highly heat-resistant polyimide having a high refractive index and excellent optical and heat-resistant properties is invented by combining a diamine compound containing a halogen atom having a high atomic refractive index and a hetero atom and an acid dianhydride. There is a purpose to do.

According to the present invention, the diamine compound comprises one selected from the group consisting of a diamine compound, an acid dianhydride compound, and a combination thereof, wherein the diamine compound is a first diamine monomer; and chlorine, brom, iodine, cyanide. , A second diamine monomer comprising one group selected from the group consisting of trifluoromethyls and combinations thereof;

The first diamine monomer may be one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer, and a combination thereof.

The first diamine monomer is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 4,4'-oxydianiline (ODA), 4,4'-methylene. Dianiline (MDA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMADA), p-cyclohexanediamine (pCHDA), p- Xylenediamine (pXDA), m-xylenediamine (mXDA), m-cyclohexanediamine (mXDA), 4,4'-diaminodiphenylsulfone (DDS), 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane (BAFP), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2'-bis (3-) Amino-4-methylphenyl) Hexafluoropropane (BAMF), 2,2'-bis (3-aminophenyl) -hexafluoropropane (BAPF), 3,5-diaminobenzotrifluoride (DABF), 2,2' -Bis (trifluoromethyl) -4,4'-diaminodiphenyl ether (BTDE), 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof are selected from the group. Can include one.

The second diamine monomer can contain at least one of the following chemical formula 1 and chemical formula 2.

(Chemical formula 1)

(Chemical formula 2)

(In the above chemical formula 1, R1 contains one selected from the group consisting of chlorine, brom, iodine, cyanide, trifluoromethyl and combinations thereof, and in the above chemical formula 2, R2 is chlorine, brom, iodine, cyanide. , Trifluoromethyl and one selected from the group consisting of combinations thereof.)

The acid dianhydride compound may be one selected from the group consisting of fluorinated aromatic acid dianhydrides, non-fluorinated aromatic acid dianhydrides and combinations thereof.

The fluorinated aromatic acid dianhydride is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (4,4'-(Hexafluoroisopropylide) diphthalic anhydride, 6FDA)), 4,4'-(4, From the group consisting of 4'-hexafluoroisopropylidenediphenoxy) bis- (phthalic anhydride) (4,4'-(4,4'-Hexafluoroisopropylidenediphenoxy) bis- (phthalic anhydride, 6-FDDPA) and combinations thereof. Can include one chosen.

The non-fluorinated aromatic acid dianhydride is pyromerlitic dianhydride (PMDA), 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3'4,4'). -Biphenylterracarboxicid dianhydride, BPDA), 3,3', 4,4'-benzophenonetetracarboxylic dianhydride (3,3', 4,4'-benzophenonetracarboxylic dianhydride, BTDA, BTDA) (4,4'-oxydiphysical anhydride, ODPA), 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propaneanhydride (2,2-Bis [4- (3,4-dicarboxyphenyloxy) ) Phenyl] propane dianhydride, BPADA), 3,3', 4,4'-diphenylsulfone tetracarboxylic acid anhydride, ethylene glycol bis (4-trimericate anhydride) (3,3', 4,4'-Diphenyl sufone) teracarboxylic dianhydride (DSDA), cyclobutanetetracarboxylic hydride (CBDA), 4- (2,5-dioxotetrachloride-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid Dianhydride (TDA), pyromellitic acid dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), bicyclo [2.2.2] Oct-7-ene. -Selected from the group consisting of 2,3,5,6-tetracarboxylic acid dianhydride (BTDA), 3,3', 4,4-biphenyltetracarboxylic acid dianhydride (s-BPDA) and combinations thereof. Can include one.

The second diamine monomer can be contained in an amount of 50 to 80 mol% based on the diamine compound.

Any one of the polyamic acids may have a viscosity of 1,000 to 10,000 cp at 23 ° C.

According to the present invention, there is provided a polyimide film comprising any one of the above polyamic acids.

When the thickness of the polyimide film is 10 to 15 μm, the refractive index is 1.7 or more, the yellowness (Yellow Index, YI.) is 10 or less, and the coefficient of thermal expansion is 100 to 250 ° C. , CTE) may be 15 ppm / ° C. or lower, the glass transition temperature may be 300 ° C. or higher, and the permeability at the 550 nm wavelength may be 88% or higher.

According to the present invention, the diamine compound comprises a step of mixing a diamine compound and a solvent to produce a mixture; and a step of adding an acid dianhydride compound to the mixture and polymerizing the mixture to produce a polyamic acid solution. , A first diamine monomer comprising one selected from the group consisting of fluorinated aromatic diamine monomers, non-fluorinated aromatic diimine monomers and combinations thereof; and chlorine, brom, iodine, cyanide, tri. Provided is a method for producing a polyamic acid, which comprises a second diamine monomer containing one selected from the group consisting of fluoromethyl and a combination thereof.

In the step of producing the mixture, the solvent is selected from the group consisting of a polar solvent, a low boiling point solvent, a low water absorption solvent, a spreading solvent and a combination thereof, and the polar solvent is m-cresol, N-methyl-. 2-Pyrrolidone (NMP), N, N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), diethyl acetate (DEA), 3-methoxy-N, N-dimethylpropanamide (DMPA), Selected from the group consisting of N, N-dimethylpropionamide (DPA), N, N-dimethyllactoamide (DML) and combinations thereof, the low boiling point solvent is tetrahydrofuran (THF), trichloromethane (chloroform, TCM). And the combination thereof, the low water-absorbent solvent is gamma-butyrolactone (GBL), 3-methoxy-N, N-dimethylpropanamide (DMPA), N, N-dimethylpropionamide (DPA). , N, N-dimethyllactoamide (DML), N-methyl-2-pyrrolidone (NMP) and combinations thereof are selected, and the spreading solvent is ethylene glycol monobutyl ether (EGBE), ethylene glycol dimethyl ether. (EGME), ethylene glycol diethyl ether (EGDE), ethylene glycol dipropyl ether (EGDPE), ethylene glycol dibutyl ether (EGDBE) and combinations thereof may be selected from the group.

The first low water-absorbent solvent mixture containing 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N-methyl-2-pyrrolidone as the low water-absorbent solvent, gamma-butyrolactone 30 to 70 mol% and N, N- Second low water absorption solvent mixture containing 30-70 mol% dimethylpropionamide, third low water absorption containing 30-70 mol% gamma-butyrolactone and 30-70 mol% 3-methoxy-N, N-dimethylpropanamide. It can contain a solvent mixture, 100 mol% N, N-dimethylpropionamide or 100 mol% 3-methoxy-N, N-dimethylpropanamide.

The solvent is a group consisting of ethylene glycol monobutyl ether (EGBE), ethylene glycol dimethyl ether (EGME), ethylene glycol diethyl ether (EGDE), ethylene glycol dipropyl ether (EGDPE), ethylene glycol dibutyl ether (EGDBE) and combinations thereof. Can include one spreading solvent selected from:

In the step of producing the mixture, the second diamine monomer can be contained in an amount of 50 to 80 mol% based on the diamine compound.

In the step of producing the mixture, the mixing may be carried out in a nitrogen atmosphere and a temperature of 25-30 ° C. for 30-60 minutes.

At the stage of producing a polyamic acid solution, one further selected from the group consisting of a plasticizer, an antioxidant, a flame retardant, a dispersant, a viscosity modifier, a leveling agent and a combination thereof is further added to the mixture. Can be done.

In the step of producing the polyamic acid solution, the polymerization may be carried out at a temperature of 10 to 70 ° C. for 6 to 48 hours.

At the stage of producing the polyamic acid solution, the diamine compound and the acid dianhydride compound constitute the solid content of the polyamic acid solution, and the content of the solid content is 10 to 40% by weight based on the polyamic acid solution. May be.

In the step of producing the polyamic acid solution, the acid dianhydride compound can contain 100 to 105 mol parts by weight (parts by mole weight) based on the diamine compound.

According to the present invention, in any one of the above-mentioned methods for producing a polyamic acid, a step of coating the polyamic acid solution on a substrate to form a transparent coating layer; and a step of heat-treating the transparent coating layer; are further included. Provided is a method for producing a polyimide film, which comprises performing the heat treatment at a temperature of 100 to 450 ° C. for 30 to 120 minutes.

According to the present invention, it is possible to produce a polyimide film which is transparent but has a high refractive index.

According to the present invention, a polyimide film having an improved yellowness can be produced.

According to the present invention, a polyimide film having a low coefficient of thermal expansion can be manufactured.

According to the present invention, it is possible to provide a polyimide film having improved optical characteristics, which can be applied to any device for the purpose of realizing a high-efficiency light source.

The effects of the present invention are not limited to the effects mentioned above. It should be understood that the effects of the present invention include any effects that can be inferred from the following description.

Comparative Example 1
In the composition shown in Table 1 below, 39.790 g (0.24 mole) of TFMB as a diamine compound was dissolved in 444.08 g of DMPA as a solvent, and the mixture was dissolved at room temperature in a nitrogen atmosphere for 30 minutes. Then, 37.872 g (0.129 mole) of BPDA, which is an acid dianhydride compound, was added, and then the mixture was stirred and polymerized for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30 ° C., and the solid content was maintained so as to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measurement with a viscosity measuring device (Blockfield DV2T, SC4-27), the viscosity was 4,800 cp.

Comparative Example 2
In the composition shown in Table 1 below, as the diamine compound, 41.148 g (0.120 mole) of the compound of the following chemical formula 3 which is a second diamine monomer is dissolved in 444.08 g of DMPA which is a solvent, and the atmosphere is nitrogen. It was allowed to dissolve at room temperature for 30 minutes. Then, 36.514 g (0.124 mole) of BPDA, which is an acid dianhydride compound, was added, and the mixture was stirred and polymerized for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30 ° C., and the solid content was maintained so as to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measurement with a viscosity measuring device (Blockfield DV2T, SC4-27), the viscosity was 4,300 cp.

(Chemical formula 3)

Comparative Example 3
In the composition shown in Table 1 below, as the diamine compound, 41.148 g (0.120 mole) of the compound of the following chemical formula 4, which is a second diamine monomer, is dissolved in 444.08 g of DMPA, which is a solvent, to create a nitrogen atmosphere. It was allowed to dissolve at room temperature for 30 minutes. Then, 36.514 g (0.124 mole) of BPDA, which is an acid dianhydride compound, was added, and the mixture was stirred and polymerized for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30 ° C., and the solid content was maintained so as to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measurement with a viscosity measuring device (Blockfield DV2T, SC4-27), the viscosity was 4,700 cp.

(Chemical formula 4)

Example 1
In the composition shown in Table 1 below, as the diamine compound, 7.728 g (0.024 mole) of TFMB which is the first diamine monomer and 33.156 g of the compound of the following chemical formula 3 which is the second diamine monomer ( 0.097 mole) was dissolved in 440.08 g of DMPA as a solvent, and the mixture was dissolved at room temperature in a nitrogen atmosphere for 30 minutes. Then, 36.778 g (0.125 mole) of BPDA, which is an acid dianhydride compound, was added, and the mixture was stirred and polymerized for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30 ° C., and the solid content was maintained so as to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measurement with a viscosity measuring device (Blockfield DV2T, SC4-27), the viscosity was 4,800 cp.

(Chemical formula 3)

Example 2
In the composition shown in Table 1 below, in Example 2, 19.532 g (0.061 mole) of TFMB, which is the first diamine monomer, and 20.949 g of the compound of chemical formula 3 which is the second diamine monomer. (0.061 mole) is dissolved in a solvent, and 37.180 g (0.126 mole) of BPDA, which is an acid dianhydride compound, is added so that the viscosity of the finally produced polyamic acid solution becomes 4,500 cp. It was carried out in the same manner as in Example 1 except that it was adjusted.

Example 3
In the composition shown in Table 1 below, Example 3 contains 11.634 g (0.036 mole) of TFMB as the first diamine monomer and 29.117 g of the compound of Chemical Formula 3 as the second diamine monomer (2). 0.085 mole) was dissolved in a solvent, and 36.911 g (0.125 mole) of BPDA, which is an acid dianhydride compound, was added to adjust the viscosity of the finally produced polyamic acid solution to 4,600 cp. Except for the above, the same procedure as in Example 1 was carried out.

Example 4
In the composition shown in Table 1 below, in Example 4, 33.156 g (0.097 mole) of the compound of the following chemical formula 4 as a second diamine monomer was dissolved in a solvent to obtain BPDA, which is an acid dianhydride compound. The same procedure as in Example 1 was carried out except that 36.778 g (0.125 mole) was added to adjust the viscosity of the finally produced polyamic acid solution to 4,700 cp.

(Chemical formula 4)

Example 5
In the composition shown in Table 1 below, in Example 5, TFMB 19.532 g (0.061 mole), which is the first diamine monomer, and 20.949 g, which is the compound of the chemical formula 4 which is the second diamine monomer, are used. 0.061 mole) was dissolved in a solvent, and 37.180 g (0.126 mole) of BPDA, which is an acid dianhydride compound, was added to adjust the viscosity of the finally produced polyamic acid solution to 4,600 cp. Except for the above, the same procedure as in Example 4 was carried out.

Example 6
In the composition shown in Table 1 below, in Example 6, TFMB 11.634 g (0.036 mole), which is the first diamine monomer, and 29.117 g, which is the compound of Chemical Formula 4 which is the second diamine monomer, are used. 0.085 mole) was dissolved in a solvent, and 36.911 g (0.125 mole) of BPDA, which is an acid dianhydride compound, was added to adjust the viscosity of the finally produced polyamic acid solution to 4,600 cp. Except for the above, the same procedure as in Example 4 was carried out.

Experimental Example (1) Evaluation of white turbidity phenomenon of polyamic acid solution Drop the polyamic acid solution prepared in Examples 1 to 6 and Comparative Examples 1 to 3 on a glass plate and use a spin coater to a certain thickness (solid content 15%). As a reference, when the thickness of the solution was 100 μm, 15 μm) was formed after the heat treatment, and the solution was left in an atmosphere at a temperature of 25 ° C. and a humidity of 90% or more for 30 minutes, and then a cloudiness phenomenon was observed. The cloudiness phenomenon occurrence level was quantified from 0 to 5 and evaluated. (0: No occurrence, 5: Serious occurrence)

(2) Evaluation of Physical Properties of Polyimide Film The polyamic acid solutions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were coated on a glass plate using a spin coater, and then heat-treated in a high-temperature convection oven. The heat treatment was carried out in a nitrogen atmosphere to obtain a final film under temperature and time conditions of 100 ° C./30 min and 350 ° C./30 min. The physical properties of the polyimide films produced in each were measured by the following methods, and the results are shown in Table 2 below.

(A) Transparency
Transmittance was measured at 550 nm using a UV-Vis NIR spectrophotometer (Shimadsu, UV-1800).

(B) Refractive index (Refractive Index)
It was measured in TE (Transverse Elictric) mode at 540 nm using a refractive index measuring device (Prism Coupler 2010M, Tricon).

(C) Yellowness (Yellowness Index, YI)
It was measured using a colorimeter (LabScan XE).

(D) Turbidity (haze)
The measurement was performed using a haze meter (TOYOSEIKI, HAZE-GARD).

(D) Thermal properties The glass transition temperature (Tg) and the coefficient of thermal expansion (CTE) of the film were measured using TMA 402 F3 manufactured by Netzsch. The force of the tension mode is set to 0.05N, and the measurement temperature is raised from 30 ° C. to 350 ° C. at a rate of 5 ° C./min as an average value in the range of 100 to 250 ° C. The coefficient of linear thermal expansion was measured. The pyrolysis temperature (Td, 1%) was measured using TG 209 F3 manufactured by Netzsch.

As shown in Table 2, when the diamine monomers having the structures of Chemical Formulas 3 and 4 are appropriately used, they can have excellent optical properties and at the same time have a high refractive index. By using DMPA, which is a low water absorption solvent, it can be confirmed that the white turbidity phenomenon did not occur during the waiting for curing after coating.

Therefore, the polyamic acid solution produced by the present invention has a coefficient of thermal expansion of 17 ppm or less in the range of 100 to 250 ° C. and a refractive index of 1.75 or more at a wavelength of 540 nm based on a film thickness of 10 to 15 μm. It can be provided as a transparent polyimide film having a transmittance of 88% or more and a yellowness (Yellow Index, YI) of 8 or less at the wavelength of.

Therefore, the polyimide film produced by the present invention satisfies high refractive index, excellent light transmittance and heat resistance characteristics, and is an OLED display, a liquid crystal element display, a TFT substrate, a flexible printing circuit substrate, and a flexible OLED surface. It is widely applicable to flexible display substrates and protective films such as lighting substrates and electronic paper substrate materials.

[Embodiment of the Invention]
The above objectives, other objectives, features and advantages of the present invention will be readily understood from the following preferred embodiments relating to the accompanying drawings. However, the present invention is not limited to the examples described herein, and may be embodied in other embodiments. On the contrary, the examples presented herein are provided to ensure that the content of the disclosure is thorough and complete, and to fully convey the ideas of the present invention to ordinary engineers.

Similar reference numerals are used for similar components in the description of each drawing. In the accompanying drawings, the dimensions of the structure are shown larger than they really are for the sake of clarity of the invention. Terms such as first and second can be used to describe various components, but the components should not be limited by the terms. These terms are used only to distinguish one component from the other. For example, the first component may be named the second component without departing from the scope of rights of the present invention, and similarly, the second component may be named the first component. The singular representation also includes multiple representations, unless otherwise stated in the context.

As used herein, terms such as "include" or "have" are intended to specify the existence of features, numbers, stages, actions, components, parts or combinations thereof described herein. And should be understood as not preliminarily excluding the presence or addition of one or more other features, numbers, stages, actions, components, parts or combinations thereof. Also, if parts such as layers, membranes, regions, plates, etc. are "above" other parts, this is not only "directly above" other parts, but also other parts in between. Including the case where there is. Conversely, if parts such as layers, membranes, regions, plates, etc. are "below" other parts, this is "just below" other parts, and there are other parts in between. Including some cases.

Unless otherwise noted, all numbers, values and / or representations of the ingredients, reaction conditions, polymer compositions and formulations used herein are essentially different. It should be understood that in all cases it is modified by the term "about" as it is an approximation that reflects the various uncertainties in the measurements that occur in obtaining such values from objects. .. Further, when a numerical range is disclosed in this description, such a range is continuous, and unless otherwise specified, all values from the minimum value to the maximum value including the maximum value in such a range are included. including. Further, when such a range refers to an integer, all integers including the minimum value to the maximum value including the maximum value are included unless otherwise specified.

As used herein, when a range is described for a variable, this variable should be understood as including all values within the stated range, including the stated end points within the range. For example, the range "5-10" includes values of 5, 6, 7, 8, 9, and 10 as well as any subrange such as 6-10, 7-10, 6-9, 7-9. Includes, including any value between valid integers within the stated range, such as 5.5, 6.5, 7.5, 5.5-8.5, 6.5-9, etc. Will be understood as a thing. Further, for example, the range of "10% to 30%" includes values such as 10%, 11%, 12%, and 13%, all integers including up to 30%, and 10% to 15% and 12%. Between reasonable integers within the range described as 10.5%, 15.5%, 25.5%, etc., including any subrange such as ~ 18%, 20% ~ 30%. It will be understood as including any value of.

The present invention relates to a method for producing a polyamic acid composition, a polyamic acid composition, a method for producing a polyimide film using the same, and a polyimide film produced by the method for producing the same, and includes the polyamic acid composition. The polyimide film, the polyamic acid composition, and the method for producing the polyimide film will be described separately.

Polyamic Acid Composition The polyamic acid of the present invention contains one selected from the group consisting of a diamine compound, an acid dianhydride compound and a combination thereof, and the diamine compound is a first diamine monomer; and a second diamine. It is characterized by containing a monomer;

Each component constituting the polyamic acid will be described.

Diamine Compound The diamine compound of the present invention is characterized by containing a first diamine monomer and a second diamine monomer.

The first diamine monomer includes one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer, and a combination thereof.

The fluorinated aromatic diamine monomer is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 2,2-bis [4- (4-aminophenoxy) phenyl]. -1,1,1,3,3,3-hexafluoropropane (BAFP), 2,2'-bis (3-amino-4-methylphenyl) hexafluoropropane (BAMF), 2,2'-bis (2,2'-bis ( 3-Aminophenyl) -Hexafluoropropane (BAPF), 3,5-diaminobenzotrifluoride (DABF), 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether (BTDE), 2, It is preferable to use one selected from the group consisting of 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof.

The non-fluorinated aromatic diamine monomer is 4,4'-oxydianiline (ODA), 4,4'-methylenedianiline (MDA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA). ), P-Methylenedianiline (pMDA), m-methylenedianiline (mMADA), p-cyclohexanediamine (pCHDA), p-xylenediamine (pXDA), m-xylenediamine (mXDA), m-cyclohexanediamine (mXDA). ), 4,4'-Diaminodiphenylsulfone (DDS), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) and combinations thereof. preferable.

The second diamine monomer contains at least one of the following chemical formula 1 and chemical formula 2.

(Chemical formula 1)

(Chemical formula 2)

At this time, in the chemical formula 1, R1 contains one selected from the group consisting of chlorine, brom, iodine, cyanide, trifluoromethyl and combinations thereof, and in the chemical formula 2, R2 is chlorine, brom, iodine. , Cyan, trifluoromethyl and one selected from the group consisting of combinations thereof.

The second diamine monomer is characterized by containing 50 to 80 mol% based on the total diamine compound. At this time, if it is less than 50 mol%, there is a limit to the improvement of the refractive index characteristic, and if it exceeds 80 mol%, there is a limit due to the deterioration of the optical characteristic.

Acid dianhydride compound The acid dianhydride compound of the present invention is characterized by containing one selected from the group consisting of fluorinated aromatic acid dianhydride, non-fluorinated aromatic acid dianhydride and combinations thereof. And.

The fluorinated aromatic acid dianhydride is an aromatic acid dianhydride having a fluorine substituent introduced therein, and is, for example, 4,4'-(hexafluoroisopropylidene) diphthalic acid anhydride (4,4'-. (Hexafluoroisopropylidene) diphthalic anhydrate, 6FDA), 4,4'-(4,4'-hexafluoroisopropylidene phenoxy) bis- (phthalic anhydride) (4,4'-(4,4'-Hexafluoroisopropyliden) It may be one selected from the group consisting of bis- (phthalic anhydride, 6-FDPDA) and combinations thereof.

The non-fluorinated aromatic acid dianhydride is an aromatic acid dianhydride in which a fluorine substituent is not introduced, and is, for example, pyromellitic dianhydride (PMDA), 3, 3', 4, 4'-biphenyltetracarboxylic acid dianhydride (3,3'4,4'-biphenyltellacarboxicid dianhydride, BPDA), 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (3,3', 4,4'-benzophenonetracarboxylic dianhydride, BTDA), 4,4'-oxydiphthalic anhydride (ODPA), 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl ] Propane Anhydride (2,2-Bis [4- (3,4-dicarboxyphenoxy) phenyl] ropane dianhydride, BPADA), 3,3', 4,4'-diphenylsulfonetetracarboxylic acid anhydride, ethylene glycol bis ( 4-Trimericate Anhydride) (3,3', 4,4'-Diphenyl sufone terracarboxylic dianhydride, DSDA), Cyclobutanetetracarboxylic Acid Dianhydride (CBDA), 4- (2,5-dioxotetrahydride-3-yl) )-1,2,3,4-Tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride (TDA), pyromellitic acid dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride. Anhydride (ODPA), Bicyclo [2.2.2] Oct-7-en-2,3,5,6-Tetracarboxylic acid dianhydride (BTDA), 3,3', 4,4-biphenyltetracarboxylic It may be one selected from the group consisting of acid dianhydride (s-BPDA) and combinations thereof.

Preferably, when the diamine compound of the present invention contains a second diamine monomer, the acid dianhydride is 4,4'-(hexafluoroisopropylidene) diphthalic acid anhydride, 4,4'-(4,). 4'-Hexafluoroisopropyridendiphenoxy) bis- (phthalic acid anhydride), cyclobutanetetracarboxylic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, bicyclo [2.2] .2] Oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 4- (2,5-dioxotetratetra-3-yl) -1,2,3,4-tetrahydronaphthalene It contains one selected from the group consisting of -1,2-dicarboxylic acid dianhydride, pyromellitic acid dianhydride, benzophenone tetracarboxylic acid dianhydride, oxydiphthalic acid dianhydride and combinations thereof.

The polyamic acid of the present invention containing the diamine compound and the acid dianhydride compound is characterized by having a viscosity of 1,000 to 10,000 cp at 23 ° C. At this time, when the viscosity of the polyamic acid is less than 1,000 cp, it is difficult to obtain an appropriate level of film thickness when producing a polyimide film, and when it exceeds 10,000 cp, uniform coating and effective solvent removal are performed. There is a problem that it cannot be done.

Method for Producing Polyamic Acid Composition When describing the method for producing the polyamic acid composition of the present invention, some of the matters overlapping with the characteristics of the composition already described in the above composition of the polyamic acid composition will be explained. do.

In order to obtain the polyimide film of the present invention, a polyamic acid (which is the same expression as a polyamic acid solution) is produced. Specifically, the polyamic acid production method is to mix a diamine compound and a solvent to prepare a mixture. It is characterized by comprising a step of producing; and a step of adding and polymerizing an acid dianhydride compound to the mixture to produce a polyamic acid solution.

Step of producing a mixture This is a step of adding a diamine compound to a prepared solvent and mixing it to form a mixture.

The diamine compound is a first diamine monomer including one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer and a combination thereof; and chlorine, brom, iodine. , A second diamine monomer comprising one selected from the group consisting of cyanide, trifluoromethyl and combinations thereof;

The fluorinated aromatic diamine monomer is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 2,2-bis [4- (4-aminophenoxy) phenyl]. It is preferable to use one selected from the group consisting of -1,1,1,3,3,3-hexafluoropropane (BAFP) and combinations thereof.

The non-fluorinated aromatic diamine monomer is 4,4'-oxydianiline (ODA), 4,4'-methylenedianiline (MDA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA). ), P-Methylenedianiline (pMDA), m-methylenedianiline (mMADA), p-cyclohexanediamine (pCHDA), p-xylenediamine (pXDA), m-xylenediamine (mXDA), m-cyclohexanediamine (mXDA). ), 4,4'-Diaminodiphenylsulfone (DDS), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) and combinations thereof. preferable.

Specifically, the second diamine monomer contains one monomer selected from the group consisting of the following chemical formula 1, chemical formula 2, and combinations thereof.

(Chemical formula 1)

(Chemical formula 2)

At this time, in the chemical formula 1, R1 contains one selected from the group consisting of chlorine, brom, iodine, cyanide, trifluoromethyl and combinations thereof, and in the chemical formula 2, R2 is chlorine, brom, iodine. , Cyan, trifluoromethyl and one selected from the group consisting of combinations thereof.

The mixing is carried out in a nitrogen atmosphere at a temperature of 25 to 30 ° C. for 30 to 60 minutes.

The second diamine monomer is preferably adjusted to be 30 to 80 mol%, preferably 50 to 80 mol% based on the entire diamine compound.

The solvent into which the diamine compound is charged may be selected from the group consisting of a polar solvent, a low boiling point solvent, a low water absorption solvent, a spreading solvent, and a combination thereof. A more specific example will be described below (however, among the following solvents, a solvent containing two or more characteristics may be described in duplicate).

The polar solvents are m-cresol, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), diethyl acetate (DEA), 3-. It may be selected from the group consisting of methoxy-N, N-dimethylpropanamide (DMPA), N, N-dimethylpropionamide (DPA), N, N-dimethyllactoamide (DML) and combinations thereof.

The low boiling point solvent can be selected from the group consisting of tetrahydrofuran (THF), trichloromethane (chloroform, TCM) and combinations thereof. Since the low boiling point solvent has high volatility, the solvent can be easily removed at the time of film production, which makes it possible to improve the physical characteristics of the produced film.

The low water absorption solvent is gamma-butyrolactone (GBL), 3-methoxy-N, N-dimethylpropanamide (DMPA), N, N-dimethylpropionamide (DPA), N, N-dimethyllactoamide (DML). , N-Methyl-2-pyrrolidone (NMP) and combinations thereof.

The low water-absorbent solvent minimizes water absorption during film production and plays an important role in improving the white turbidity phenomenon. In order to improve the white turbidity phenomenon during solution casting at room temperature, gamma-butyrolactone (GBL) and N- First low water absorption solvent mixture of methyl-2-pyrrolidone (NMP), second low water absorption solvent mixture of gamma-butyrolactone (GBL) and N, N-dimethylpropionamide (DPA), gamma-butyrolactone (GBL) and Select a third low water absorption solvent mixture of 3-methoxy-N, N-dimethylpropanamide (DMPA) or 3-methoxy-N, N-dimethylpropanamide (DMPA) and N, N-dimethylpropionamide. It is preferable to select (DPA) individually.

When a mixture of gamma-butyrolactone and N-methyl-2-pyrrolidone is used as the low water absorption solvent, gamma-butyrolactone 30 to 70 mol% and N-methyl-2-pyrrolidone 30 to 70 mol% should be used. Is preferable. More preferably, 50 to 70 mol% of gamma-butyrolactone and 30 to 50 mol% of N-methyl-2-pyrrolidone are used.

When a mixture of the gamma-butyrolactone and N, N-dimethylpropionamide is used as the low water absorption solvent, 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N, N-dimethylpropionamide are used. Preferably, 50 to 70 mol% of gamma-butyrolactone and 30 to 50 mol% of N, N-dimethylpropionamide are used.

When a mixture of the gamma-butyrolactone and 3-methoxy-N, N-dimethylpropanamide is used as the low water absorption solvent, gamma-butyrolactone 30 to 70 mol% and 3-methoxy-N, N-dimethylpropanamide 30 are used. It is preferable to use ~ 70 mol%. More preferably, 50 to 70 mol% of gamma-butyrolactone and 30 to 50 mol% of 3-methoxy-N, N-dimethylpropanamide are used.

When the N, N-dimethylpropionamide alone or the 3-methoxy-N, N-dimethylpropanamide alone is selected as the low water absorption solvent, 100 mol% can be used alone without the addition of other solvents. preferable.

Examples of the spreading solvent include ethylene glycol monobutyl ether (EGBE), ethylene glycol dimethyl ether (EGME), ethylene glycol diethyl ether (EGDE), ethylene glycol dipropyl ether (EGDPE), ethylene glycol dibutyl ether (EGDBE), and combinations thereof. One selected from the group consisting of can be used.

The spreadable solvent plays an important role in improving the wetting property, but it improves the spreadability of the solution during solution casting, prevents the solution from shrinking, and obtains a film having excellent uniformity. To. Therefore, 10 to 40 mol%, preferably 10 to 30 mol% of ethylene glycol monobutyl ether can be used.

Step of producing a polyamic acid solution This is a step of adding an acid dianhydride compound to the produced mixture and producing a polyamic acid solution by a polymerization reaction.

The acid dianhydride compound to be charged may include one selected from the group consisting of fluorinated aromatic acid dianhydrides, non-fluorinated aromatic acid dianhydrides and combinations thereof. The example is omitted because it overlaps with the content described in the above-mentioned polyamic acid composition.

In the present invention, the diamine compound and the acid dianhydride compound constitute a solid content in the polyamic acid solution, and at this time, the content of the solid content is preferably 10 to 40% by weight based on the polyamic acid solution. .. More preferably, the solid content is 10 to 25% by weight. At this time, if the solid content is less than 10% by weight, there is a limit to increasing the thickness of the film during the production of the polyimide film, and if the solid content exceeds 40% by weight, the polyamic acid solution is used. There is a problem that there is a limit to adjusting the viscosity of the film.

The diamine compound and the acid dianhydride compound constituting the solid content contain 95 to 100 mol% of the diamine compound and 100 to 105 mol by weight of the acid dianhydride compound (parts by mole weight). It has been.

The polymerization is preferably carried out at a temperature of 10 to 70 ° C. for 6 to 48 hours.

At this stage, in addition to the acid dianhydride, a catalyst can be further added to enhance the reactivity. At this time, any catalyst can be used that does not defeat the object of the present invention and can improve the reactivity within a range that does not significantly impair the effect. For example, it may be selected from the group consisting of trimethylamine, xylene, pyridine, quinoline and combinations thereof. In the present invention, in addition to the catalyst, any one selected from the group consisting of plasticizers, antioxidants, flame retardants, dispersants, viscosity modifiers, leveling agents and combinations thereof may be further included. However, this can also be selected and used as necessary within a range that does not significantly impair the object and effect of the present invention.

Method for Producing Polyimide Film The polyimide film of the present invention can be produced by coating the produced polyamic acid solution on a substrate to form a transparent coating layer and heat-treating the transparent coating layer.

To specifically explain the method for producing the polyimide film of the present invention, the polyamic acid solution of the present invention having a specific viscosity is coated on a prepared base material such as glass, but the coating method used at this time is particularly limited. Not done. As an example, it may be selected from the group consisting of spin coating, dip coating, solvent casting, slot die coating, spray coating and combinations thereof.

The heat treatment can be performed by a convection method using a general oven, but the heat treatment conditions are 100 to 450 ° C. for 30 to 120 minutes. Preferably, the heat treatment can be performed under temperature and time conditions of 100 ° C. for 30 minutes and 350 ° C. for 30 minutes. This is a condition that can maximize the characteristics of the polyimide film of the present invention used as an optical film at the same time as removing an appropriate solvent.

Polyimide film The polyamic acid composition of the present invention optimizes the composition of a novel specific diamine compound and acid dianhydride and a solvent (organic solvent) that does not cause white turbidity, and the amount used thereof, and has heat resistance properties, optical properties, and refraction. It is characterized by providing a polyimide film having excellent rate characteristics and high transparency. Specifically, the polyimide film of the present invention is produced by the method for producing a polyimide film, and the polyimide film has a refractive index of 1.7 or more and a yellowness (Yellow Index) when the thickness is 10 to 15 μm. , YI) is 10 or less, the thermal expansion coefficient (CTE) is 15 ppm / ° C or less at 100 to 250 ° C, the glass transition temperature is 300 ° C or more, and transmission at 550 nm wavelength. The degree is 85% or more, and it is characterized by having high transparency. At this time, the transmittance of the polyimide film of the present invention is more preferably 88% or more, and the yellowness can have a value of 8 or less.

The polyimide film of the present invention can be used in various fields, but in particular, flexible devices, tablet PCs, wearable devices and flexible OLED lighting that require the realization of a high-efficiency light source that requires high transparency and high refractive index characteristics. It can be usefully used as a substrate material.

Claims (15)

Includes one selected from the group consisting of diamine compounds, acid dianhydride compounds and combinations thereof.
The diamine compound is a first diamine monomer including one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer and a combination thereof; and chlorine, brom, iodine. , A second diamine monomer comprising one group selected from the group consisting of cyanide, trifluoromethyl and combinations thereof; polyamic acid. The first diamine monomer is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 4,4'-oxydianiline (ODA), 4,4'-methylene. Dianiline (MDA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMADA), p-cyclohexanediamine (pCHDA), p- Xylenediamine (pXDA), m-xylenediamine (mXDA), m-cyclohexanediamine (mXDA), 4,4'-diaminodiphenylsulfone (DDS), 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane (BAFP), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2'-bis (3-) Amino-4-methylphenyl) Hexafluoropropane (BAMF), 2,2'-bis (3-aminophenyl) -hexafluoropropane (BAPF), 3,5-diaminobenzotrifluoride (DABF), 2,2' -Bis (trifluoromethyl) -4,4'-diaminodiphenyl ether (BTDE), 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof are selected from the group. The polyamic acid according to claim 1, which comprises one. The polyamic acid according to claim 1, wherein the second diamine monomer contains at least one of the following chemical formula 1 and chemical formula 2.
(Chemical formula 1)

(Chemical formula 2)

(In the above chemical formula 1, R1 contains one selected from the group consisting of chlorine, brom, iodine, cyanide, trifluoromethyl and combinations thereof, and in the above chemical formula 2, R2 is chlorine, brom, iodine, cyanide. , Trifluoromethyl and one selected from the group consisting of combinations thereof.) The first aspect of the present invention is characterized in that the acid dianhydride compound contains one selected from the group consisting of a fluorinated aromatic acid dianhydride, a non-fluorinated aromatic acid dianhydride, and a combination thereof. The polyamic acid described. The fluorinated aromatic acid dianhydride is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (4,4'-(Hexafluoroisopropylide) diphthalic anhydride, 6FDA)), 4,4'-(4, From the group consisting of 4'-hexafluoroisopropylidenediphenoxy) bis- (phthalic anhydride) (4,4'-(4,4'-Hexafluoroisopropylidenediphenoxy) bis- (phthalic anhydride, 6-FDPDA) and combinations thereof. The polyamic acid according to claim 4, which comprises one selected. The non-fluorinated aromatic acid dianhydride is pyromerlitic dianhydride (PMDA), 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3'4,4'). -Biphenylterracarboxicid dianhydride, BPDA), 3,3', 4,4'-benzophenonetetracarboxylic dianhydride (3,3', 4,4'-benzophenonetracarboxylic dianhydride, BTDA, BTDA) (4,4'-oxydiphysical anhydride, ODPA), 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propaneanhydride (2,2-Bis [4- (3,4-dicarboxyphenyloxy) ) Phenyl] propane dianhydride, BPADA), 3,3', 4,4'-diphenylsulfone tetracarboxylic acid anhydride, ethylene glycol bis (4-trimericate anhydride) (3,3', 4,4'-Diphenyl sufone) teracarboxylic dianhydride (DSDA), cyclobutanetetracarboxylic hydride (CBDA), 4- (2,5-dioxotetrachloride-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid Dianhydride (TDA), pyromellitic acid dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), bicyclo [2.2.2] Oct-7-ene. -Selected from the group consisting of 2,3,5,6-tetracarboxylic acid dianhydride (BTDA), 3,3', 4,4-biphenyltetracarboxylic acid dianhydride (s-BPDA) and combinations thereof. The polyamic acid according to claim 4, which comprises one. A step of mixing a diamine compound and a solvent to produce a mixture; and a step of adding an acid dianhydride compound to the mixture and polymerizing the mixture to produce a polyamic acid solution;
The diamine compound is a first diamine monomer including one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer and a combination thereof; and chlorine, brom, iodine. , A second diamine monomer comprising one selected from the group consisting of cyanide, trifluoromethyl and combinations thereof; a method for producing a polyamic acid. In the stage of producing a mixture, the solvent is selected from the group consisting of polar solvents, low boiling point solvents, low water absorption solvents, spreadable solvents and combinations thereof.
The polar solvents are m-cresol, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), diethyl acetate (DEA), 3-. Selected from the group consisting of methoxy-N, N-dimethylpropanamide (DMPA), N, N-dimethylpropionamide (DPA), N, N-dimethyllactoamide (DML) and combinations thereof.
The low boiling point solvent is selected from the group consisting of tetrahydrofuran (THF), trichloromethane (chloroform, TCM) and combinations thereof.
The low water absorption solvent is gamma-butyrolactone (GBL), 3-methoxy-N, N-dimethylpropanamide (DMPA), N, N-dimethylpropionamide (DPA), N, N-dimethyllactoamide (DML). , N-Methyl-2-pyrrolidone (NMP) and combinations thereof.
The spreading solvent is from ethylene glycol monobutyl ether (EGBE), ethylene glycol dimethyl ether (EGME), ethylene glycol diethyl ether (EGDE), ethylene glycol dipropyl ether (EGDPE), ethylene glycol dibutyl ether (EGDBE) and combinations thereof. The polyamic acid production method according to claim 7, wherein the method is selected from the above group. The first low water-absorbent solvent mixture containing 30 to 70 mol% of gamma butyrolactone and 30 to 70 mol% of N-methyl-2-pyrrolidone as the low water-absorbent solvent, gamma-butyrolactone 30 to 70 mol% and N, N- Second low water absorption solvent mixture containing 30-70 mol% dimethylpropionamide, third low water absorption containing 30-70 mol% gamma-butyrolactone and 30-70 mol% 3-methoxy-N, N-dimethylpropanamide. The method for producing a polyamic acid according to claim 8, wherein the solvent mixture contains 100 mol% of N, N-dimethylpropionamide or 100 mol% of 3-methoxy-N, N-dimethylpropanamide. The solvent is a group consisting of ethylene glycol monobutyl ether (EGBE), ethylene glycol dimethyl ether (EGME), ethylene glycol diethyl ether (EGDE), ethylene glycol dipropyl ether (EGDPE), ethylene glycol dibutyl ether (EGDBE) and combinations thereof. The method for producing polyamic acid according to claim 7, further comprising one spreading solvent selected from the above. The method for producing a polyamic acid according to claim 7, wherein the second diamine monomer is contained in an amount of 50 to 80 mol% based on the diamine compound in the stage of producing the mixture. In the step of producing the mixture, the mixing is carried out in a nitrogen atmosphere at a temperature of 25 to 30 ° C. for 30 to 60 minutes, and the polymerization is carried out at a temperature of 10 to 70 ° C. for 6 to 48 hours. The method for producing a polyamic acid according to claim 7. At the stage of producing the polyamic acid solution, the diamine compound and the acid dianhydride compound constitute the solid content of the polyamic acid solution, and the content of the solid content is 10 to 40% by weight based on the polyamic acid solution. The method for producing a polyamic acid according to claim 7, wherein the method is characterized by the above. The method for producing a polyamic acid according to claim 7, wherein the acid dianhydride compound contains 100 to 105 mol parts by weight (parts by mole weight) based on the diamine compound in the step of producing the polyamic acid solution. .. In the method for producing a polyamic acid according to claim 7,
Further comprising: coating the substrate with the polyamic acid solution to form a transparent coating layer; and heat treating the transparent coating layer;
The polyimide film manufacturing method, wherein the heat treatment is performed at a temperature of 100 to 450 ° C. for 30 to 120 minutes.