KR102260540B1 - manufacturing method of polyamic acid composition, polyamic acid composition, manufacturing method of polyimide film using the polyamic acid composition and polyimide film using 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 through the method, more precisely a diamine compound having a hetero atom and a halogen atom introduced therein; The present invention relates to a method for preparing a polyamic acid composition capable of improving optical properties including an acid dianhydride compound, a polyamic acid composition, a method for preparing a polyimide film using the same, and a polyimide film prepared through the method.

Description

A method of manufacturing a polyamic acid composition, a polyamic acid composition, a method of manufacturing a polyimide film using the same, and a polyimide film manufactured through the manufacturing method. {manufacturing method of polyamic acid composition, polyamic acid composition, manufacturing method of polyimide film using the polyamic acid composition and polyimide film using the same}

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 through the method, more precisely a diamine compound having a hetero atom and a halogen atom introduced therein; The present invention relates to a method for preparing a polyamic acid composition capable of improving optical properties including an acid dianhydride compound, a polyamic acid composition, a method for preparing a polyimide film using the same, and a polyimide film prepared through the method.

The substrate material of a flexible display, which is attracting attention as a next-generation display device, should be light, unbreakable, bendable, and have no shape restrictions due to easy processability. A polymer material capable of manufacturing a thin film because it is lighter than a glass substrate currently used as a display substrate material, does not break, and is easy to manufacture, is attracting attention as the most suitable material for realizing a flexible display.

Conventional flexible devices generally use an organic light emitting diode (OLED) display, and a TFT process with a high process temperature (300 to 500° C.) is used. Polymeric materials that can withstand these high processing temperatures are extremely limited. Therefore, in recent years, as a candidate for a plastic substrate for a transparent flexible display, the use of polyimide resin having excellent heat resistance and dimensional stability is increasing.

In addition, with the continuous development of organic light emitting diode technology, the company has a wide portfolio such as flexible tablet PCs and wearable devices, thereby establishing itself as a next-generation display. At the same time, it is expanding into lighting applications with its unique excellent white light color quality. In order to reproduce the realization of a high-efficiency light source through efficient light extraction in the field of lighting applications, interest in polymer resins with excellent optical properties and high refractive index is also increasing.

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 an organic light emitting diode lighting application. The difference in refractive index between the light source and the polymer capsule material causes total internal reflection when light passes through the light source at a specific angle of incidence and passes through the capsule material, thereby lowering the light extraction efficiency of the device. In particular, excellent optical properties and high refractive index are required for application to advanced optical devices. Since conventional polyimide has a low refractive index in the range of about 1.3 to 1.6, light extraction efficiency is reduced.

Korean Patent Registration No. 10-1704010 relates to a diamine compound having a substituent of an aromatic ring containing a hetero atom and a halogen atom introduced therein, and a polyamic acid and polyimide prepared thereby, having a high refractive index and a low birefringence. Although a transparent film is provided, there is a limit to providing a film having excellently improved heat resistance and shape stability while satisfying a high refractive index of 1.7 or more.

Korean Patent No. 10-1704010

The present invention is intended to solve the above problems, and its specific purpose is as follows.

In the present invention, it is an object of the present invention to invent a high heat-resistant polyimide having a high refractive index and excellent optical and heat resistance properties through a combination of a diamine compound containing a halogen atom and a hetero atom having a high atom intrinsic refractive index and an acid dianhydride.

According to the present invention, a diamine compound, an acid dianhydride compound, and one selected from the group consisting of combinations thereof, wherein the diamine compound is a first diamine monomer; and a second diamine monomer comprising one group selected from the group consisting of chlorine, bromine, iodine, cyan, trifluoromethyl, and combinations thereof; provides a polyamic acid comprising a.

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 combinations 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 (mMDA), p-cyclohexanediamine (pCHDA) , p-xylylenediamine (pXDA), m-xylylenediamine (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- It may include one selected from the group consisting of hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof.

The second diamine monomer may include one monomer selected from the group consisting of the following Chemical Formulas 1 and 2, and combinations thereof.

[Formula 1]

[Formula 2]

(In Formula 1, R1 includes one selected from the group consisting of chlorine, bromine, iodine, cyan, trifluoromethyl, and combinations thereof, and R2 in Formula 2 is chlorine, bromine, iodine, cyan, trifluoro and one selected from the group consisting of methyl and 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'-(Hexafluoroisopropylidene)diphthalic anhydride, 6FDA)), 4,4'-(4,4'- One selected from the group consisting of hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride)(4,4'-(4,4'-Hexafluoroisopropylideenediphenoxy)bis-(phthalic anhydride, 6-FDPDA) and combinations thereof may include.

The non-fluorinated aromatic acid dianhydride is pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3'4,4'-biphenyltetracarboxylic acid) dianhydride, BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride, BTDA), 4,4'-oxydiphthalic anhydride ( 4,4′-oxydiphthalic anhydride, ODPA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane anhydride (2,2-Bis[4-(3,4-dicarboxyphenoxy)phenyl ]propane dianhydride, BPADA), 3,3',4,4'-diphenyl sulfone tetracarboxylic anhydride, ethylene glycol bis(4-trimellitate anhydride) (3,3',4,4'-Diphenyl sufone) tetracarboxylic dianhydride, DSDA), cyclobutanetetracarboxylic dianhydride (CBDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1, 2-dicarboxylic dianhydride (TDA), pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), bicyclo[2.2.2]oct -7ene-2,3,5,6-tetracarboxylic dianhydride (BTDA), 3,3',4,4-bipheniretracarboxylic dianhydride (s-BPDA), and combinations thereof It may include one selected from the group consisting of.

The second diamine monomer may be included 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 polyamic acids.

The polyimide film has a thickness of 10 to 15 μm, a refractive index of 1.7 or more, a yellowness (YI) of 10 or less, a coefficient of thermal expansion (CTE) at 100 to 250° C. of 15 ppm/° C. or less, glass The transition temperature may be 300° C. or more and transmittance at a wavelength of 550 nm may be 88% or more.

According to the present invention, preparing a mixture by mixing a diamine compound and a solvent; and preparing a polyamic acid solution by adding and polymerizing an acid dianhydride compound to the mixture, wherein the diamine compound is one selected from the group consisting of a fluorinated aromatic diamine monomer, a non-fluorinated aromatic diamine monomer, and a combination thereof A first diamine monomer comprising; and a second diamine monomer comprising one selected from the group consisting of chlorine, bromine, iodine, cyan, trifluoromethyl, and combinations thereof.

In the step of preparing 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 spreadable 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), diethylacetate (DEA), 3-methoxy-N,N-dimethyl propanamide (DMPA) ), N,N-dimethyl propinoamide (DPA), N,N-dimethyllactamide (DML), and combinations thereof, and the low boiling point solvent is tetrahydrofuran (THF), trichloromethane (chloroform, TCM) and combinations thereof, and the low water absorption solvent is gamma-butyrolactone (GBL), 3-methoxy-N,N-dimethylpropanamide (DMPA), N,N- It is selected from the group consisting of dimethyl propinoamide (DPA), N,N-dimethyllactamide (DML), N-methyl-2-pyrrolidone (NMP), and combinations thereof, and the spreadable solvent is ethylene glycol mono Selected from the group consisting of butyl 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 be

A first low water absorption solvent mixture comprising 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N-methyl-2-pyrrolidone as the low water absorption solvent, 30 to 70 mol% of gamma-butyrolactone, and A second low water absorption solvent mixture comprising 30 to 70 mol% of N,N-dimethyl propinoamide, 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol of 3-methoxy-N,N-dimethyl propanamide % of a third low absorption solvent mixture, 100 mol% of N,N-dimethyl propinoamide or 100 mol% of 3-methoxy-N,N-dimethyl propanamide.

The 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 It may include one spreadable solvent selected from the group consisting of.

In the step of preparing the mixture, the second diamine monomer may be included in an amount of 50 to 80 mol% based on the diamine compound.

In the step of preparing the mixture, the mixing may be performed in a nitrogen atmosphere and at a temperature of 25 to 30° C. for 30 to 60 minutes.

In the step of preparing the polyamic acid solution, one 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 may be further added to the mixture.

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

In the step of preparing the polyamic acid solution, the diamine compound and the acid dianhydride compound may constitute a solid content of the polyamic acid solution, and the content of the solid content may be 10 to 40 wt% based on the polyamic acid solution.

In the step of preparing the polyamic acid solution, the acid dianhydride compound may include 100 to 105 mol% based on the diamine compound.

According to the present invention, in any one of the polyamic acid manufacturing methods, the method comprising: coating the polyamic acid solution on a substrate to form a transparent coating layer; and heat-treating the transparent coating layer; further comprising, wherein the heat treatment is performed at a temperature of 100 to 450° C. for 30 to 120 minutes.

According to the present invention, it is possible to manufacture a transparent polyimide film having a high refractive index.

According to the present invention, it is possible to manufacture a polyimide film with improved yellowness.

According to the present invention, it is possible to manufacture a polyimide film having a low coefficient of thermal expansion.

According to the present invention, it is possible to provide a polyimide film with improved optical properties that can be applied to all devices for the purpose of realizing a high-efficiency light source.

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

The above objects, other objects, features and advantages of the present invention will be easily understood through the following preferred embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged than the actual size for clarity of the present invention. Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, when a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" another part, but also the case where there is another part in between. Conversely, when a part, such as a layer, film, region, plate, etc., is "under" another part, this includes not only cases where it is "under" another part, but also cases where another part is in the middle.

Unless otherwise specified, all numbers, values, and/or expressions expressing quantities of ingredients, reaction conditions, polymer compositions and formulations used herein, contain all numbers, values and/or expressions in which such numbers essentially occur in obtaining such values, among others. Since they are approximations reflecting various uncertainties in the measurement, it should be understood as being modified by the term “about” in all cases. Also, where this disclosure discloses numerical ranges, such ranges are continuous and inclusive of all values from the minimum to the maximum inclusive of the range, unless otherwise indicated. Furthermore, when such ranges refer to integers, all integers inclusive from the minimum to the maximum inclusive are included, unless otherwise indicated.

In this specification, when a range is described for a variable, the variable will be understood to include all values within the stated range including the stated endpoints of the range. For example, a range of “5 to 10” includes the values of 5, 6, 7, 8, 9, and 10, as well as any subranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc. It will be understood to include any value between integers that are appropriate for the scope of the recited range, such as 5.5, 6.5, 7.5, 5.5 to 8.5 and 6.5 to 9, and the like. Also for example, a range of "10% to 30%" includes values such as 10%, 11%, 12%, 13%, and all integers up to and including 30%, as well as 10% to 15%, 12% to It will be understood to include any subrange, such as 18%, 20% to 30%, etc., as well as any value between reasonable integers within the scope of the recited range, such as 10.5%, 15.5%, 25.5%, and the like.

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 prepared through the method for producing the same, and the polyamic acid composition and a polyimide film and polyamide comprising the same The mixed acid composition and the manufacturing method of the polyimide film will be described separately.

polyamic acid composition

The polyamic acid of the present invention includes 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 monomer.

Each component constituting the polyamic acid will be described.

diamine compound

The diamine compound of the present invention is characterized in that it comprises 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 combinations 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 ( 3-Aminophenyl)-hexafluoropropane (BAPF), 3,5-diaminobenzotrifluoride (DABF), 2,2'-bis(trifluoromethyl)-4,4'-diaminodi It is preferable to use one selected from the group consisting of phenyl ether (BTDE), 2,2-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 (mMDA), p-cyclohexanediamine (pCHDA), p-xylylenediamine (pXDA), m-xylylenediamine (mXDA), m-cyclohexanediamine ( mXDA), 4,4'-diaminodiphenylsulfone (DDS), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and combinations thereof desirable.

The second diamine monomer includes one monomer selected from the group consisting of the following Chemical Formulas 1 and 2, and combinations thereof.

[Formula 1]

[Formula 2]

In this case, in Formula 1, R1 includes one selected from the group consisting of chlorine, bromine, iodine, cyan, trifluoromethyl, and combinations thereof, and R2 in Formula 2 is chlorine, bromine, iodine, cyan, trifluoro and one selected from the group consisting of romethyl and combinations thereof.

The second diamine monomer is characterized in that it contains 50 to 80 mol% based on the total diamine compound. In this case, when it is less than 50 mol%, there is a limit to the improvement of the refractive index characteristic, and when it is more than 80 mol%, there is a limit according to the deterioration of the optical characteristic.

acid dianhydride compounds

The acid dianhydride compound of the present invention is characterized in that it comprises 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 an aromatic acid dianhydride introduced with a fluorine substituent, for example, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (4,4'-(Hexafluoroisopropylidene)diphthalic anhydride, 6FDA )), 4,4'-(4,4'-hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride)(4,4'-(4,4'-Hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride, 6-FDPDA) and combinations thereof may be selected from the group consisting of.

The non-fluorinated aromatic acid dianhydride is an aromatic acid dianhydride into which a fluorine substituent is not introduced, for example, pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxyl Acid dianhydride (3,3'4,4'-biphenyltetracarboxylic acid dianhydride, BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (3,3',4,4'-benzophenonetetracarboxylic 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]propane dianhydride, BPADA), 3,3',4,4'-diphenyl sulfone tetracarboxylic acid anhydride, ethylene glycol bis(4-trimellitate anhydride) (3,3',4,4'-Diphenyl sufone tetracarboxylic dianhydride, DSDA), cyclobutanetetracarboxylic dianhydride (CBDA), 4-(2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride (TDA), pyromellitic acid dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), oxydip talic dianhydride (ODPA), bicyclo[2.2.2]oct-7ene-2,3,5,6-tetracarboxylic dianhydride (BTDA), 3,3',4,4-bipheniretra It may be one selected from the group consisting of carboxylic acid dihydrate (s-BPDA) and combinations thereof.

Preferably, when the second diamine monomer is included as the diamine compound of the present invention, the acid dianhydride is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-(4,4'- Hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride), cyclobutanetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, bicyclo[2.2. 2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetra and one selected from the group consisting of hydronaphthalene-1,2-dicarboxylic acid dianhydride, pyromellitic acid dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic dianhydride, and combinations thereof.

The viscosity of the polyamic acid of the present invention comprising the diamine compound and the acid dianhydride compound is characterized in that 1,000 to 10,000cp at 23 ℃. At this time, if the viscosity of the polyamic acid is less than 1,000cp, it may be difficult to obtain a film thickness of an appropriate level when manufacturing the polyimide film, and if it exceeds 10,000cp, there is a problem that uniform coating and effective solvent removal cannot be achieved.

Method for preparing polyamic acid composition

In the description of the method for preparing the polyamic acid composition of the present invention, the description will be made by excluding some of the features overlapping with the characteristics of the composition previously described in the composition of the polyamic acid composition.

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 prepared. Specifically, the polyamic acid production method includes preparing a mixture by mixing a diamine compound and a solvent; and preparing a polyamic acid solution by adding and polymerizing an acid dianhydride compound to the mixture.

preparing the mixture

In this step, the diamine compound is added to the prepared solvent and mixed to form a mixture.

The diamine compound may include 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 a second diamine monomer comprising one selected from the group consisting of chlorine, bromine, iodine, cyan, 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 (mMDA), p-cyclohexanediamine (pCHDA), p-xylylenediamine (pXDA), m-xylylenediamine (mXDA), m-cyclohexanediamine ( mXDA), 4,4'-diaminodiphenylsulfone (DDS), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and combinations thereof desirable.

The second diamine monomer specifically includes one monomer selected from the group consisting of the following Chemical Formulas 1 and 2, and combinations thereof.

[Formula 1]

[Formula 2]

In this case, in Formula 1, R1 includes one selected from the group consisting of chlorine, bromine, iodine, cyan, trifluoromethyl, and combinations thereof, and R2 in Formula 2 is chlorine, bromine, iodine, cyan, trifluoro and one selected from the group consisting of romethyl and combinations thereof.

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

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 to which the diamine compound is added may be selected from the group consisting of a polar solvent, a low boiling point solvent, a low water absorption solvent, a spreadable solvent, and combinations thereof. A more specific example will be described below. (However, in the case of a solvent containing two or more characteristics among the solvents listed below, the description may be overlapped.)

The polar solvent is m-cresol, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), diethyl acetate ( DEA), 3-methoxy-N,N-dimethyl propanamide (DMPA), N,N-dimethyl propinoamide (DPA), N,N-dimethyllactamide (DML), and combinations thereof. can

The low boiling point solvent may be selected from the group consisting of tetrahydrofuran (THF), trichloromethane (chloroform, TCM), and combinations thereof. The low boiling point solvent is highly volatile, and thus it is easy to remove the solvent during film production, which improves the physical properties of the prepared film.

The low absorption solvent is gamma-butyrolactone (GBL), 3-methoxy-N,N-dimethylpropanamide (DMPA), N,N-dimethyl propinoamide (DPA), N,N-dimethyllactamide ( DML), N-methyl-2-pyrrolidone (NMP), and combinations thereof.

The low water absorption solvent plays an important role in improving cloudiness by minimizing water absorption during film production. In order to improve cloudiness when casting a solution at room temperature, gamma-butyrolactone (GBL) and N-methyl-2-p A first low absorption solvent mixture of rolidone (NMP), a second low absorption solvent mixture of gamma-butyrolactone (GBL) and N,N-dimethyl propinoamide (DPA), gamma-butyrolactone (GBL) and Choose a third low absorption solvent mixture of 3-methoxy-N,N-dimethyl propanamide (DMPA), or 3-methoxy-N,N-dimethyl propanamide (DMPA) and N,N-dimethyl propino It is preferred to select each of the amides (DPA) alone.

When the mixture of gamma-butyrolactone and N-methyl-2-pyrrolidone is used as the low water absorption solvent, 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N-methyl-2-pyrrolidone It is preferred to use mole %. 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 gamma-butyrolactone and N,N-dimethyl propinoamide is used as the low water absorption solvent, 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N,N-dimethyl propinoamide use Preferably, 50 to 70 mol% of gamma-butyrolactone and 30 to 50 mol% of N,N-dimethyl propinoamide are used.

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

When selecting N,N-dimethyl propinoamide alone or 3-methoxy-N,N-dimethyl propanamide alone as the low water absorption solvent, it is preferable to use 100 mol% alone without adding another solvent.

Examples of the spreadable 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 these One selected from the group consisting of combinations of can be used.

The spreadable solvent plays an important role in improving wetting, and improves the spreadability of the solution when casting the solution, prevents the solution from shrinking, and makes it possible to obtain a film with excellent uniformity. For this, 10 to 40 mol% of ethylene glycol monobutyl ether may be used, preferably 10 to 30 mol%.

Preparing a polyamic acid solution

It is a step of preparing a polyamic acid solution by adding an acid dianhydride compound to the prepared mixture and polymerization reaction.

The input acid dianhydride compound may include one selected from the group consisting of a fluorinated aromatic acid dianhydride, a non-fluorinated aromatic acid dianhydride, and a combination thereof, and specific examples are omitted because they overlap with those already described in the polyamic acid composition. let it do

In the present invention, the diamine compound and the acid dianhydride compound constitute a solid content in the polyamic acid solution, wherein the content of the solid content is preferably 10 to 40 wt% based on the polyamic acid solution. More preferably, the solid content is included in an amount of 10 to 25% by weight. At this time, when the content of the solid content is less than 10% by weight, there is a limit in increasing the thickness of the film when manufacturing the polyimide film, and when the content of the solid content is more than 40% by weight, there is a problem in that there is a limit in controlling the viscosity of the polyamic acid solution.

In the case of the diamine compound and the acid dianhydride compound constituting the solid content, the diamine compound is contained in an amount of 95 to 100 mol%, and the acid dianhydride compound is contained in an amount of 100 to 105 mol%.

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

In this step, a catalyst other than the acid dianhydride may be further added to increase reactivity. In this case, the catalyst used is not particularly limited as long as the reactivity can be improved in a range that does not violate the purpose of the present invention and 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, which also significantly improves the object and effect of the present invention It can be selected and used as needed within the range that does not damage.

Manufacturing method of polyimide film

The polyamic acid solution prepared above may be coated on a substrate to form a transparent coating layer, and the transparent coating layer may be heat-treated to prepare the polyimide film of the present invention.

Looking specifically at the manufacturing method of the polyimide film of the present invention, the polyamic acid solution of the present invention having a specific viscosity is coated on a prepared substrate such as glass, and the coating method used in this case is not particularly limited. For 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 may be performed in a convection manner through a general oven, and the heat treatment conditions are performed at 100 to 450° C. for 30 to 120 minutes. Preferably, the heat treatment may be performed under temperature and time conditions at 100° C. for 30 minutes and at 350° C. for 30 minutes. This is a condition capable of maximizing the properties of the polyimide film of the present invention used as an optical film at the same time as removal of an appropriate solvent.

polyimide film

The composition of the polyamic acid of the present invention is a novel specific diamine compound and acid dianhydride and a solvent (organic solvent) that does not cause cloudiness, and the composition and usage thereof are optimized to provide excellent heat resistance, optical properties, and refractive index properties. It is characterized by providing a polyimide film having transparency. Specifically, the polyimide film of the present invention is manufactured through the method for manufacturing the polyimide film. When the polyimide film has a thickness of 10 to 15 μm, a refractive index of 1.7 or more and a yellowness index (YI) of 10 or less , a coefficient of thermal expansion (CTE) of 15ppm/℃ or less at 100 to 250℃, a glass transition temperature of 300℃ or more, and a transmittance of 85% or more at a wavelength of 550nm, and is characterized by high transparency. In this case, the transmittance of the polyimide film of the present invention is more preferably 88% or more, and the yellowness may have a value of 8 or less.

The polyimide film of the present invention can be used in various fields. In particular, it is usefully used as a flexible device, tablet PC, wearable device, and flexible OLED lighting substrate material that requires a high-efficiency light source that requires high transparency and high refractive index characteristics. can be

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Comparative Example 1

As 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 dissolved at room temperature in a nitrogen atmosphere for 30 minutes. Thereafter, 37.872 g (0.129 mole) of BPDA, an acid dianhydride compound, was added, followed by stirring and polymerization for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30° C., and the solid content was maintained to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measuring with a viscosity measuring device (Brookfield DV2T, SC4-27), the viscosity was 4,800 cp.

Comparative Example 2

As the composition shown in Table 1 below, as the diamine compound, 41.148 g (0.120 mole) of the compound of Formula 3, which is a second diamine monomer, was dissolved in 444.08 g of DMPA as a solvent, and dissolved at room temperature in a nitrogen atmosphere for 30 minutes. Thereafter, 36.514 g (0.124 mole) of BPDA, an acid dianhydride compound, was added, followed by stirring and polymerization for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30° C., and the solid content was maintained to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measuring with a viscosity measuring device (Brookfield DV2T, SC4-27), the viscosity was 4,300 cp.

[Formula 3]

Comparative Example 3

As the composition shown in Table 1 below, as the diamine compound, 41.148 g (0.120 mole) of a compound of Formula 4 below, which is a second diamine monomer, was dissolved in 444.08 g of DMPA as a solvent and dissolved at room temperature in a nitrogen atmosphere for 30 minutes. Thereafter, 36.514 g (0.124 mole) of BPDA, an acid dianhydride compound, was added, followed by stirring and polymerization for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30° C., and the solid content was maintained to be 15% by weight based on the total weight of the polyamic acid solution. At this time, the viscosity was 4,700 cp as a result of measuring with a viscosity measuring device (Brookfield DV2T, SC4-27).

[Formula 4]

Example 1

As the composition shown in Table 1 below, as the diamine compound, 7.728 g (0.024 mole) of TFMB as the first diamine monomer and 33.156 g (0.097 mole) of the compound of Formula 3 as the second diamine monomer were dissolved in 440.08 g of DMPA as a solvent to dissolve nitrogen It was dissolved at room temperature in the atmosphere for 30 minutes. Thereafter, 36.778 g (0.125 mole) of BPDA, an acid dianhydride compound, was added thereto, followed by stirring and polymerization for 24 hours to prepare a polyamic acid solution. The polymerization temperature was maintained at 30° C., and the solid content was maintained to be 15% by weight based on the total weight of the polyamic acid solution. At this time, as a result of measuring with a viscosity measuring device (Brookfield DV2T, SC4-27), the viscosity was 4,800cp.

[Formula 3]

Example 2

As the composition shown in Table 1 below, Example 2 is prepared by dissolving 19.532 g (0.061 mole) of TFMB as the first diamine monomer and 20.949 g (0.061 mole) of the compound of Formula 3 as the second diamine monomer in a solvent, and an acid dianhydride compound Phosphorus BPDA was added in the same manner as in Example 1, except that the viscosity of the finally prepared polyamic acid solution was adjusted to 4,500 cp by adding 37.180 g (0.126 mole).

Example 3

As a composition shown in Table 1 below, Example 3 is obtained by dissolving 11.634 g (0.036 mole) of TFMB, a first diamine monomer, and 29.117 g (0.085 mole), of a compound of Formula 3, which is a second diamine monomer, in a solvent, and an acid dianhydride compound It was carried out in the same manner as in Example 1, except that 36.911 g (0.125 mole) of phosphorus BPDA was added to adjust the viscosity of the finally prepared polyamic acid solution to be 4,600 cp.

Example 4

As the composition shown in Table 1 below, Example 4 was obtained by dissolving 33.156 g (0.097 mole) of a compound of Formula 4 below as a second diamine monomer in a solvent, and finally adding 36.778 g (0.125 mole) of BPDA, an acid dianhydride compound, to the final composition. It was carried out in the same manner as in Example 1, except that the viscosity of the polyamic acid solution prepared as 4,700cp was adjusted.

[Formula 4]

Example 5

As a composition shown in Table 1 below, Example 5 is prepared by dissolving 19.532 g (0.061 mole) of TFMB, a first diamine monomer, and 20.949 g (0.061 mole), of a compound of Formula 4, which is a second diamine monomer, in a solvent, and an acid dianhydride compound Phosphorus BPDA was added in the same manner as in Example 4, except that the viscosity of the finally prepared polyamic acid solution was adjusted to 4,600 cp by adding 37.180 g (0.126 mole).

Example 6

As the composition shown in Table 1 below, Example 6 is prepared by dissolving 11.634 g (0.036 mole) of TFMB as the first diamine monomer and 29.117 g (0.085 mole) of the compound of Formula 4 as the second diamine monomer in a solvent, and an acid dianhydride compound It was carried out in the same manner as in Example 4, except that 36.911 g (0.125 mole) of phosphorus BPDA was added to adjust the viscosity of the finally prepared polyamic acid solution to be 4,600 cp.

division Example comparative example One 2 3 4 5 6 One 2 3 composition acid dianhydride *BPDA 100 100 100 100 100 100 100 100 100 diamine *TFMB 20 50 70 20 50 70 100 - - *Formula 3 80 50 30 - - - - 100 - *Formula 4 - - - 80 50 30 - - 100 menstruum
(Unit: mole %) DMPA = 100 *BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-biphenyltetracarboxylic dianhydride)
*TFMB: 2,2'-bis(trifluoromethyl)-benzidine (2,2'-bis(trifluoromethyl)benzidine)
*Formula 3: 2,2'-dibromo-4,4'-diaminophenyl (2,2'-Dibromo-4,4'-diaminobiphenyl)
*Formula 4: 2,2'-diamino-4,4'-dibromophenyl (2,2'-Dimino-4,4'-dibromobiphenyl)

Experimental example

(1) Polyamic acid solution cloudiness evaluation

By dropping the polyamic acid solution prepared in Examples 1 to 6 and Comparative Examples 1 to 3 on a glass plate and using a spin coater to form a predetermined thickness (based on solid content of 15%, when the thickness of the solution is 100 μm, 15 μm after heat treatment), After leaving it for 30 minutes in an atmosphere with a temperature of 25° C. and a humidity of 90% or more, cloudiness was observed. The level of occurrence of cloudiness was numerically evaluated from 0 to 5. (0: no occurrence, 5: occurrence of sweating)

(2) Polyimide film property evaluation

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 under a nitrogen atmosphere, and a final film was obtained at a temperature and time conditions of 100°C/30min and 350°C/30min. The physical properties of the polyimide films prepared in each were measured in the following manner, and the results are shown in Table 2 below.

(a) Transmittance

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

(b) Reflective Index

It was measured in TE (Transverse Elictric) mode at 540 nm using a refractometer (Metricon, Prism Coupler 2010M).

(c) Yellowness Index (YI)

Measurements were made using a colorimeter (LabScan XE).

(d) haze

It was measured using a haze meter (TOYOSEIKI, HAZE-GARD).

(d) thermal properties

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

physical property measurement target value Example comparative example One 2 3 4 5 6 One 2 3 Properties
Measure Viscosity
(cp, 23℃) 1000
~
7000 4800 4500 4600 4700 4600 4600 4800 4300 4700 level of cloudiness
(Room temperature, RH>90%) 0 0 0 0 0 0 0 0 0 0 Thickness (㎛) 10 10 10 10 10 10 10 10 10 10 Transmittance (%, @550nm) >85 86 88 90 87 89 90 91 84 88 Haze <1 0.98 0.90 0.53 0.84 0.66 0.58 0.53 0.89 0.78 Y.I. <10 8 7 6 7 7 7 6 10 7 Refractive Index (@540nm) <1.70 1.83 1.80 1.75 1.77 1.75 .75 1.74 1.71 1.88 CTE
(100 ~
250℃) ppm/℃ <30 9 11 13 17 17 16 14 8 17 Td 1% ℃ >400 461 459 460 451 453 452 459 463 453

As shown in Table 2, when the diamine monomers having the structures of Chemical Formulas 3 and 4 are appropriately used, excellent optical properties and high refractive index can be obtained. In addition, it can be confirmed that cloudiness did not occur when waiting for curing after coating by using DMPA, which is a low water absorption solvent.

Thus, the polyamic acid solution prepared by the present invention has a thermal expansion coefficient of 17 ppm or less in a range of 100 to 250 ° C., a refractive index of 1.75 or more at a wavelength of 540 nm, and 550 nm based on a film thickness of 10 to 15 μm. It may be provided as a transparent polyimide film having a transmittance at a wavelength of 88% or more and a Yellow Index (YI) of 8 or less.

Therefore, the polyimide film manufactured according to the present invention satisfies high refractive index, excellent light transmittance and heat resistance, and thus, displays for OLED, displays for liquid crystal devices, TFT substrates, flexible printed circuit boards, flexible OLED surface lighting substrates, and electronics. It can be widely applied to a substrate and a protective film for a flexible display such as a substrate material for paper.

Claims (22)

Containing one selected from the group consisting of diamine compounds, acid dianhydride compounds, and combinations thereof,
The diamine compound is a first diamine monomer; and
a second diamine monomer comprising bromine; and
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 (mMDA), p-cyclohexanediamine (pCHDA) , p-xylylenediamine (pXDA), m-xylylenediamine (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- containing one selected from the group consisting of hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof,
The second diamine monomer includes a monomer of Formula 2 below,
The acid dianhydride compound includes one selected from the group consisting of fluorinated aromatic acid dianhydrides, non-fluorinated aromatic acid dianhydrides, and combinations thereof,
The second diamine monomer is included in an amount of 50 to 80 mol% based on the diamine compound,
The acid dianhydride compound is polyamic acid, characterized in that it contains 100 to 105 mol% based on the diamine compound.
[Formula 2]

(R2 in Formula 2 includes bromine.) delete delete delete delete According to claim 1,
The fluorinated aromatic acid dianhydride is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (4,4'-(Hexafluoroisopropylidene)diphthalic anhydride, 6FDA)), 4,4'-(4,4'- One selected from the group consisting of hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride)(4,4'-(4,4'-Hexafluoroisopropylidenediphenoxy)bis-(phthalic anhydride, 6-FDPDA) and combinations thereof Polyamic acid comprising a. According to claim 1,
The non-fluorinated aromatic acid dianhydride is pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3'4,4'-biphenyltetracarboxylic acid) dianhydride, BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride, BTDA), 4,4'-oxydiphthalic anhydride ( 4,4′-oxydiphthalic anhydride, ODPA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane anhydride (2,2-Bis[4-(3,4-dicarboxyphenoxy)phenyl ]propane dianhydride, BPADA), 3,3',4,4'-diphenyl sulfone tetracarboxylic anhydride, ethylene glycol bis(4-trimellitate anhydride) (3,3',4,4'-Diphenyl sufone) tetracarboxylic dianhydride, DSDA), cyclobutanetetracarboxylic dianhydride (CBDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1, 2-dicarboxylic dianhydride (TDA), pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), bicyclo[2.2.2]oct -7ene-2,3,5,6-tetracarboxylic dianhydride (BTDA), 3,3',4,4-bipheniretracarboxylic dianhydride (s-BPDA), and combinations thereof Polyamic acid comprising one selected from the group consisting of. delete According to claim 1,
The polyamic acid has a viscosity of 1,000 to 10,000cp at 23 ℃ polyamic acid, characterized in that. A polyimide film comprising the polyamic acid of any one of claims 1, 6, 7 and 9. 11. The method of claim 10,
When the polyimide film has a thickness of 10 to 15 μm,
refractive index of 1.7 or more,
Yellow Index (YI) 10 or less,
Coefficient of thermal expansion (CTE) 15ppm/℃ or less at 100 to 250 ℃,
A glass transition temperature of 300°C or higher and
A polyimide film having a transmittance of 88% or more at a wavelength of 550 nm. preparing a mixture by mixing a diamine compound and a solvent; and
Including; preparing a polyamic acid solution by adding and polymerizing an acid dianhydride compound to the mixture;
The diamine compound may include 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
a second diamine monomer comprising bromine; and
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 (mMDA), p-cyclohexanediamine (pCHDA) , p-xylylenediamine (pXDA), m-xylylenediamine (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- containing one selected from the group consisting of hydroxyphenyl) hexafluoropropane (BAHH) and combinations thereof,
The second diamine monomer includes a monomer of Formula 2 below,
The acid dianhydride compound includes one selected from the group consisting of fluorinated aromatic acid dianhydrides, non-fluorinated aromatic acid dianhydrides, and combinations thereof,
In the step of preparing the mixture, the second diamine monomer is included in an amount of 50 to 80 mol% based on the diamine compound,
In the step of preparing the polyamic acid solution, the acid dianhydride compound is a polyamic acid production method, characterized in that it contains 100 to 105 mol% based on the diamine compound.
[Formula 2]

(R2 in Formula 2 includes bromine.) 13. The method of claim 12,
In the step of preparing 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 spreadable solvent, and combinations thereof,
The polar solvent is m-cresol, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), diethyl acetate ( DEA), 3-methoxy-N,N-dimethyl propanamide (DMPA), N,N-dimethyl propinoamide (DPA), N,N-dimethyllactamide (DML), and combinations thereof become,
The low boiling point solvent is selected from the group consisting of tetrahydrofuran (THF), trichloromethane (chloroform, TCM), and combinations thereof,
The low absorption solvent is gamma-butyrolactone (GBL), 3-methoxy-N,N-dimethylpropanamide (DMPA), N,N-dimethyl propinoamide (DPA), N,N-dimethyllactamide ( DML), N-methyl-2-pyrrolidone (NMP), and combinations thereof,
Examples of the spreadable 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 these A method for producing polyamic acid, characterized in that it is selected from the group consisting of a combination of 14. The method of claim 13,
A first low water absorption solvent mixture comprising 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol% of N-methyl-2-pyrrolidone, 30 to 70 mol% of gamma-butyrolactone, and A second low water absorption solvent mixture comprising 30 to 70 mol% of N,N-dimethyl propinoamide, 30 to 70 mol% of gamma-butyrolactone and 30 to 70 mol of 3-methoxy-N,N-dimethyl propanamide % of the third low-absorbency solvent mixture, 100 mol% of N,N-dimethyl propinoamide or 100 mol% of 3-methoxy-N,N-dimethyl propanamide. 13. The method of claim 12,
The 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 A polyamic acid production method comprising one spreadable solvent selected from the group consisting of. delete 13. The method of claim 12,
In the step of preparing the mixture, the mixing is performed in a nitrogen atmosphere at a temperature of 25 to 30° C. for 30 to 60 minutes. 13. The method of claim 12,
In the step of preparing the polyamic acid solution, one 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. 13. The method of claim 12,
In the step of preparing the polyamic acid solution, the polymerization is performed at a temperature of 10 to 70° C. for 6 to 48 hours. 13. The method of claim 12,
In the step of preparing the polyamic acid solution, the diamine compound and the acid dianhydride compound constitute the solid content of the polyamic acid solution,
The content of the solid content is a polyamic acid production method, characterized in that 10 to 40% by weight based on the polyamic acid solution. delete The method for preparing the polyamic acid according to any one of claims 12 to 15 and 17 to 20,
forming a transparent coating layer by coating the polyamic acid solution on a substrate; and
Further comprising; heat-treating the transparent coating layer;
The heat treatment method for producing a polyimide film, characterized in that the heat treatment is carried out at a temperature of 100 to 450 ℃ 30 to 120 minutes.