阅读说明：本技术 聚酰亚胺系组合物及聚酰亚胺系膜 (Polyimide composition and polyimide film ) 是由 安民石 裵珉英 朴势周 车荣哲 郑载勋 赵英云 金东敏 尹赫敏 赵泰杓 金炳郁 于 2019-06-05 设计创作，主要内容包括：本发明提供用于显示器的聚酰亚胺系组合物及利用其制备的紫外线稳定性优秀的聚酰亚胺系膜。提供一种聚酰亚胺系膜,其包含：上述聚酰亚胺或聚酰胺-酰亚胺共聚物；以及选自由2-羟基苯基苯并三唑衍生物、2-羟基苯基三嗪衍生物、受阻胺衍生物及它们的混合物组成的组中的一种以上的光稳定剂,相对于100重量份的聚酰亚胺或聚酰胺-酰亚胺共聚物,上述光稳定剂为0.01至6重量份。(The invention provides a polyimide composition for a display and a polyimide film prepared by using the same and having excellent ultraviolet stability. Provided is a polyimide-based film comprising: the above polyimide or polyamide-imide copolymer; and one or more light stabilizers selected from the group consisting of 2-hydroxyphenylbenzotriazole derivatives, 2-hydroxyphenyltriazine derivatives, hindered amine derivatives, and mixtures thereof, in an amount of 0.01 to 6 parts by weight per 100 parts by weight of the polyimide or polyamide-imide copolymer.)

1. A polyimide-based film, comprising:

A polyimide or polyamide-imide copolymer; and

A light stabilizer selected from the group consisting of 2-hydroxyphenylbenzotriazole derivatives, 2-hydroxyphenyltriazine derivatives, hindered amine derivatives and mixtures thereof,

The light stabilizer is 0.01 to 6 parts by weight with respect to 100 parts by weight of the polyimide or the polyamide-imide copolymer.

2. The polyimide-based film according to claim 1,

The 2-hydroxyphenylbenzotriazole derivative is selected from the group consisting of a compound represented by the following chemical formula 2a, a compound represented by the chemical formula 2b, and a mixture thereof,

Chemical formula 2a

In the chemical formula 2a, R₁To R₈each independently containing a hydrogen, oxygen, nitrogen, halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms,

Chemical formula 2b

in the chemical formula 2b, R₁To R₈each independently comprises hydrogen, oxygen, nitrogen, a halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms.

3. the polyimide-based film according to claim 2,

the 2-hydroxyphenylbenzotriazole derivative represented by the chemical formula 2a is selected from the group consisting of compounds represented by the following chemical formulae 2a-1 to 2a-7,

Chemical formula 2a-1Chemical formula 2a-2Chemical formula (II)2a-3Chemical formula 2a-4Chemical formula 2a-5Chemical formula 2a-6chemical formula 2a-7

4. The polyimide-based film according to claim 2,

The 2-hydroxyphenylbenzotriazole derivative represented by the chemical formula 2b is a compound represented by the following chemical formula 2b-1,

Chemical formula 2b-1

5. The polyimide-based film according to claim 1,

The 2-hydroxyphenyltriazine derivative is a compound represented by the following chemical formula 2c,

Chemical formula 2c

In the chemical formula 2c, R₁To R₆Each independently comprises hydrogen, oxygen, nitrogen, a halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms.

6. The polyimide-based film according to claim 5,

The 2-hydroxyphenyltriazine derivative represented by the chemical formula 2c is selected from the group consisting of compounds represented by the following chemical formulae 2c-1 to 2c-5,

chemical formula 2c-1Chemical formula 2c-2

Chemical formula 2c-3Chemical formula 2c-4

Chemical formula 2c-5

7. The polyimide-based film according to claim 1,

The hindered amine derivative includes a structure represented by the following chemical formula 3,

Chemical formula 3

8. The polyimide-based film according to claim 7,

The hindered amine derivative is selected from compounds represented by the following chemical formula 3-1 to chemical formula 3-7,

Chemical formula 3-1n is an integer of 1 to 100,

Chemical formula 3-2n is an integer of 1 to 100,

Chemical formula 3-3

chemical formula 3-4n is an integer of 1 to 100,

Chemical formula 3-5n is an integer of 10 to 19,

Chemical formula 3-6n is an integer of 1 to 100, chemical formula 3-7

9. The polyimide-based film according to claim 1, wherein the polyimide-based film has a yellow index of 5 or less, a change rate of the yellow index after ultraviolet irradiation of 60% or less, an elongation of 5% or more, and a change rate of the elongation after ultraviolet irradiation of 50% or less.

10. the polyimide-based film according to claim 1,

The polyamide-imide copolymer is represented by the following chemical formula 1a,

Chemical formula 1a

In the chemical formula 1a, X is a 4-valent group having 4 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, Y1 and Y2 are 2-valent groups having 6 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, Z is a 2-valent group having 6 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, n is an integer of 10 to 10000, and m is an integer of 10 to 10000.

11. the polyimide-based film according to claim 1, wherein the light stabilizer is at least one selected from the group consisting of a 2-hydroxyphenylbenzotriazole derivative or a 2-hydroxyphenyltriazine derivative, a hindered amine derivative, and a mixture thereof.

12. A polyimide-based composition, comprising:

100 parts by weight of a polyimide or polyamide-imide copolymer;

0.01 to 6 parts by weight of a light stabilizer with respect to 100 parts by weight of the polyimide or polyamide-imide copolymer; and

The balance of the organic solvent is the organic solvent,

The light stabilizer is more than one selected from the group consisting of 2-hydroxyphenylbenzotriazole derivatives, 2-hydroxyphenyltriazine derivatives, hindered amine derivatives and mixtures thereof,

The viscosity of the polyimide-based composition is 100 to 10000 cP.

13. The polyimide-based composition according to claim 12, wherein the solvent is selected from the group consisting of: an amide solvent selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, 3-methoxy-N, N-dimethylpropionamide, N-ethylpyrrolidone and mixtures thereof; a ketone-based solvent selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and mixtures thereof; an ether-based solvent selected from the group consisting of tetrahydrofuran, 1, 3-dioxolane, 1, 4-dioxane, and a mixture thereof; an ester-based solvent selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate, gamma-butyrolactone, alpha-caprolactone, beta-propiolactone, delta-valerolactone, and mixtures thereof; a symmetric glycol diether system solvent selected from the group consisting of methyl monoglyme (1, 2-dimethoxyethane), methyl diglyme (bis (2-methoxyethyl) ether), methyl triglyme (1, 2-bis (2-methoxyethoxy) ethane), methyl tetraglyme (bis [2- (2-methoxyethoxyethyl) ] ether), ethyl monoglyme (1, 2-diethoxyethane), ethyl diglyme (bis (2-ethoxyethyl) ether), butyl diglyme (bis (2-butoxyethyl) ether), and mixtures thereof, or selected from the group consisting of dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-propyl ether, propylene glycol phenyl ether, methyl diglyme, bis (2-methoxyethyl) ether, methyl triglyme (1, ethers in the group consisting of dipropylene glycol dimethyl ether, 1, 3-dioxolane, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol monoethyl ether and mixtures thereof; and mixtures thereof.

14. The polyimide-based composition according to claim 12, wherein the light stabilizer comprises a hindered amine derivative and one or more selected from the group consisting of a 2-hydroxyphenylbenzotriazole derivative, a 2-hydroxyphenyltriazine derivative, and mixtures thereof.

Technical Field

the present invention relates to a polyimide-based composition and a polyimide-based film having excellent ultraviolet stability prepared therefrom, and more particularly, to a polyimide-based composition used in a flexible display and a polyimide-based film having excellent ultraviolet stability prepared therefrom.

Background

As the trend of displays is shifted from the conventional Rigid (Rigid) form to the flexible form, the conventional glass substrate is replaced with the plastic substrate. For use as a flexible display substrate, it must be transparent like glass and have little dimensional change under high temperature conditions. Further, excellent mechanical properties that are not easily broken and easily bent are required.

Recently, in order to realize a curved display, a conventional glass substrate has been replaced with a polyimide film. In general, in the case of a display, a polyimide substrate may be exposed to ultraviolet rays during a manufacturing process or a process in which a user uses a product. In general, polyimide has excellent heat resistance and mechanical properties, but has the following problems: when exposed to ultraviolet rays, optical properties and mechanical properties are degraded, and in this case, display properties in bending may be degraded, and transmittance may be low due to formation of a strong Charge Transfer Complex (Charge Transfer Complex) within a molecule or between molecules.

Korean patent No. 10-2015-0190313 discloses a polyamide-imide copolymer for improving the optical properties and mechanical properties of a polyimide film. The substrate may be exposed to ultraviolet rays during a manufacturing process of the flexible display or a process of using a product by a user. In general, polyamide-imide copolymer films are difficult to use as flexible display substrate materials when they are degraded in optical properties and mechanical properties when exposed to ultraviolet light for a long period of time.

Disclosure of Invention

Problems to be solved

Accordingly, an object of the present invention is to provide a polyimide-based composition having improved ultraviolet stability.

Another object of the present invention is to provide a polyimide-based film suitable for a flexible display.

Means for solving the problems

In order to achieve the above object, the present invention provides a polyimide-based film comprising: a polyimide or polyamide-imide copolymer; and one or more light stabilizers selected from the group consisting of 2-hydroxyphenylbenzotriazole derivatives, 2-hydroxyphenyltriazine derivatives, hindered amine derivatives, and mixtures thereof, in an amount of 0.01 to 6 parts by weight per 100 parts by weight of the polyimide or polyamide-imide copolymer.

Also, the present invention provides a polyimide-based composition comprising: 100 parts by weight of a polyimide or polyamide-imide copolymer; 0.01 to 6 parts by weight of a light stabilizer relative to 100 parts by weight of the above polyimide or polyamide-imide copolymer; and the balance of organic solvent, the light stabilizer is selected from more than one of the group consisting of 2-hydroxyphenyl benzotriazole derivatives, 2-hydroxyphenyl triazine derivatives, hindered amine derivatives and their mixture, and the viscosity of the polyimide-based composition is 100 to 10000 cP.

effects of the invention

The polyimide-based composition and the polyimide-based film having excellent ultraviolet stability prepared therefrom according to the present invention have the following effects: not only is excellent in elongation and yellowness index, but also has a low rate of change in elongation and yellowness index even when exposed to ultraviolet rays.

Detailed Description

the present invention will be described in more detail below.

The present invention provides a polyimide composition and a polyimide film having excellent ultraviolet stability, the polyimide film comprising: 100 parts by weight of a polyimide or polyamide-imide copolymer; 0.01 to 6 parts by weight of a light stabilizer, which is one or more selected from the group consisting of a 2-hydroxyphenylbenzotriazole derivative, a 2-hydroxyphenyltriazine derivative, a hindered amine derivative, and a mixture thereof, per 100 parts by weight of the polyimide or polyamide-imide copolymer.

The present invention includes a polyamide-imide copolymer represented by the following chemical formula 1a as a polyimide or polyimide copolymer represented by the following chemical formula 1.

Chemical formula 1

In chemical formula 1, X is a 4-valent group having 4 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, and Y is a 2-valent group having 6 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure.

chemical formula 1a

In chemical formula 1a, X is a 4-valent group having 4 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, Y1 and Y2 are 2-valent groups having 6 to 30 carbon atoms and having an aromatic ring or aliphatic ring structure, and Y1 and Y2 may have the same structure. Z is a 2-valent group having 6 to 30 carbon atoms and having an aromatic or aliphatic ring structure, specifically including para-Phenyl (para-Phenyl), meta-Phenyl (meta-Phenyl), biphenyl (Bi-Phenyl), etc., preferably having a para-Phenyl (para-Phenyl) structure in terms of high-temperature dimensional stability, and preferably having a meta-Phenyl (meta-Phenyl) structure in order to achieve a low yellow index. N is an integer of 10 to 10000, and m is an integer of 10 to 10000.

The polyimide compound can form a Charge Transfer Complex (Charge Transfer Complex) having a strong intramolecular or intermolecular Charge Transfer property, and thus has high heat resistance and excellent mechanical properties as compared with conventional polyesters, polypropylenes, and polyamides.

The polyamide-imide copolymer can be obtained by copolymerizing monomers containing a Diamine (Diamine) and a dianhydride (Dianhy anhydride). The Diamine (Diamine) monomer is 2,2'-Bis (trifluoromethyl) benzidine (2,2' -Bis (trifluoromethyl) benzidine), 3 '-sulfonyldiphenylamine (3,3' -sulfobenzidine), 4'-diaminodiphenyl sulfone (4,4' -diaminodiphenyl sulfone), Bis [4- (4-aminophenoxy) phenyl ] sulfone (Bis [4- (4-aminophenoxy) phenyl ] sulfone), 3,4'-Oxydianiline (3,4' -Oxydianiline), 4'- (1,3-Phenylenedioxy) diphenylamine (4,4' - (1,3-Phenylenedioxy) dianiline), or the like.

The Dianhydride is 2,2-Bis (3, 4-dicarboxyphenyl) hexafluoropropane Dianhydride (2,2-Bis (3, 4-anhydrophenylhexahydro) hexafluoro propane Dianhydride), 3',4,4' -Biphenyltetracarboxylic Dianhydride (3,3',4,4' -Biphenyltetracarboxylic Dianhydride), 3',4,4' -diphenylsulfonetetracarboxylic Dianhydride (3,3',4,4' -diphenylsulfonecarboxylic Dianhydride), 3',4,4' -Benzophenonetetracarboxylic Dianhydride (3,3',4,4' -Benzophenonetetracarboxylic Dianhydride), or the like.

The present invention may include a light stabilizer containing a 2-hydroxyphenylbenzotriazole derivative selected from the group consisting of compounds represented by the following chemical formula 2a and compounds represented by the chemical formula 2b, and mixtures thereof.

Chemical formula 2a

In the above chemical formula 2a, R₁To R₈Which may be the same or different, R₁to R₈Each independently comprises hydrogen, oxygen, nitrogen, a halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms.

Chemical formula 2b

In the above chemical formula 2b, R₁To R₈which may be the same or different, R₁To R₈Each independently comprises hydrogen, oxygen, nitrogen, a halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms.

the 2-hydroxyphenylbenzotriazole derivatives represented by the above chemical formula 2a include derivatives represented by the following chemical formulae 2a-1 to 2 a-7.

Chemical formula 2a-1Chemical formula 2a-2Chemical formula 2a-3Chemical formula 2a-4Chemical formula 2a-5chemical formula 2a-6chemical formula (II)2a-7

The 2-hydroxyphenylbenzotriazole derivative represented by the above chemical formula 2b includes derivatives represented by the following chemical formula 2 b-1.

Chemical formula 2b-1

the light stabilizer may further include a 2-hydroxyphenyltriazine (2-hydroxyphenyl triazine) derivative represented by the following chemical formula 2 c.

Chemical formula 2c

In the above chemical formula 2c, R₁To R₆Which may be the same or different, R₁To R₆each independently comprises hydrogen, oxygen, nitrogen, a halogen atom, or a linear or branched hydrocarbon group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms.

the 2-hydroxyphenyltriazine (2-Hydroxy phenyl triazine) derivative represented by the above chemical formula 2c includes derivatives represented by the following chemical formulae 2c-1 to 2 c-5.

chemical formula 2c-1Chemical formula 2c-2

Chemical formula 2c-3Chemical formula 2c-4

Chemical formula 2c-5

The content of the above-mentioned 2-hydroxyphenylbenzotriazole derivative or 2-hydroxyphenyltriazine derivative may be 0.01 to 6 parts by weight relative to 100 parts by weight of the polyimide or polyamide-imide copolymer. When the content is less than the above range, there is a problem that the change rate of the yellowness index and the elongation upon the exposure to ultraviolet rays sharply increases, and when the content exceeds the above range, there is a problem that the initial yellowness index of the film increases.

Further, the light stabilizer may contain one or more compounds composed of a 2-hydroxyphenylbenzotriazole (2-hydroxyphenylbenzotriazole) derivative or a 2-hydroxyphenyltriazine derivative.

The light stabilizer comprising the above-mentioned 2-hydroxyphenylbenzotriazole derivative or 2-hydroxyphenyltriazine derivative absorbs ultraviolet rays to be thermally released. Specifically, when a 2-hydroxyphenylbenzotriazole derivative is added to a polyamide-imide copolymer, the derivative converts ultraviolet rays into heat, whereby decomposition of the copolymer by ultraviolet rays can be reduced.

in the present invention, the light stabilizer includes a Hindered amine (Hindered amine) derivative containing a structure represented by the following chemical formula 3.

Chemical formula 3

specifically, derivatives represented by the following chemical formula 3-1 to chemical formula 3-7 are included.

Chemical formula 3-1(n is an integer of 1 to 100), chemical formula 3-2(n is an integer of 1 to 100.),

Chemical formula 3-3

Chemical formula 3-4(n is an integer of 1 to 100.),

Chemical formula 3-5(n is an integer of 10 to 19),

chemical formula 3-6(n is an integer of 1 to 100.),

Chemical formula 3-7

The content of the above hindered amine derivative may be 0.01 to 6 parts by weight with respect to 100 parts by weight of the polyimide or polyamide-imide copolymer as a whole. When the content is less than the above range, there is a problem that the change rate of the yellowness index and the elongation upon the exposure to ultraviolet rays sharply increases, and when the content exceeds the above range, there is a problem that the initial yellowness index of the film increases.

the Hindered amine (Hindered amine) derivative can reduce decomposition of the polyamide-imide copolymer by removing radicals generated by ultraviolet rays.

The present invention may comprise one or more light stabilizers selected from the group consisting of the above-mentioned 2-hydroxyphenylbenzotriazole (2-hydroxyphenylbenzotriazole) derivative, 2-hydroxyphenyltriazine (2-hydroxyphenyltriazine) derivative, hindered amine derivative, and mixtures thereof, preferably may comprise two light stabilizers, more preferably may comprise one or more hindered amine derivatives, and further may comprise one or more light stabilizers selected from the group consisting of 2-hydroxyphenylbenzotriazole and 2-hydroxyphenyltriazine derivatives, whereby light stability may be more improved. The above light stabilizer may be contained in an amount of 0.01 to 6 parts by weight in total, relative to 100 parts by weight of the polyimide or polyamide-imide copolymer. When the content is less than the above range, there is a problem that the change rate of the yellowness index and the elongation upon the exposure to ultraviolet rays sharply increases, and when the content exceeds the above range, there is a problem that the initial yellowness index of the film increases.

When the hindered amine derivative and one or more of the 2-hydroxyphenylbenzotriazole or 2-hydroxyphenyltriazine derivatives are contained together, the weight ratio of them may be 3: 7 to 7: 3 (hindered amine derivative: 2-hydroxyphenylbenzotriazole or 2-hydroxyphenyltriazine derivative), but is not limited thereto. When the weight ratio is deviated from the above-mentioned one, there is a problem that initial yellow index characteristics and the like of the film are deteriorated.

The polyimide-based film of the present invention comprises the above polyimide or polyamide-imide copolymer and at least one light stabilizer selected from the group consisting of a 2-hydroxybenzotriazole derivative, a 2-hydroxyphenyltriazine derivative, a hindered amine derivative, and a mixture thereof.

The polyimide film has a yellowness index of 10 or less, preferably 5 or less, and a YI change rate of 60% or less, preferably 30% or less, after ultraviolet irradiation. When the Yellow Index (YI) is out of the range, there is a problem that it is difficult to use as a display substrate due to yellowish color.

the elongation (Strain) of the film is 3% or more, preferably 7% or more, and the change rate of the elongation (Strain) after ultraviolet irradiation is 50% or less, preferably less than 40%. When the elongation (Strain) is out of the above range, the film is fragile and the flexibility is lowered.

The present invention provides a polyimide-based composition comprising: 100 parts by weight of a polyimide or polyamide-imide copolymer; 0.01 to 6 parts by weight of a light stabilizer with respect to 100 parts by weight of the polyimide or the polyamide-imide copolymer; and the balance of solvent, the light stabilizer is selected from more than one of the group consisting of 2-hydroxyphenyl benzotriazole derivatives, 2-hydroxyphenyl triazine derivatives, hindered amine derivatives and their mixture, and the viscosity of the polyimide-based composition is 100 to 10000 cP.

The polyimide or polyamide-imide copolymer and the light stabilizer are the same as those described in the polyimide-based film, and therefore, the description thereof is omitted.

The solvent used in the present invention is not particularly limited, and may include amide solvents such as Dimethylformamide (DMF), Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP), 3-methoxy-N, N-dimethylpropionamide (M3DMPA), N-Dimethylpropionamide (DMPA), and N-ethylpyrrolidone (NEP); ketone solvents such as acetone, Methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone; ether solvents such as Tetrahydrofuran (THF), 1, 3-dioxolane, and 1, 4-dioxane; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, γ -butyrolactone, α -caprolactone, β -propiolactone and δ -valerolactone; methyl monoglyme (1, 2-dimethoxyethane), methyl diglyme (bis (2-methoxyethyl) ether), methyl triglyme (1, 2-bis (2-methoxyethoxy) ethane), methyl tetraglyme (bis [2- (2-methoxyethoxyethyl) ] ether), ethyl monoglyme (1, 2-diethoxyethane), ethyl diglyme (bis (2-ethoxyethyl) ether), butyl diglyme (bis (2-butoxyethyl) ether) and other symmetric glycol diether solvents or dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-propyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, Organic solvents such as ethers including 1, 3-dioxolane, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and ethylene glycol monoethyl ether. The content of the above solvent may be a content in which the viscosity of the composition can exhibit 100 to 10000 cP.

If the solvent content is excessive or insufficient and the viscosity of the composition is out of the above range, there is a possibility that the film cannot be smoothly coated in the production of a polyimide film, which may cause a problem of spots or the like.

the invention comprises the following steps: a step of adding at least one light stabilizer selected from the group consisting of a 2-hydroxybenzotriazole derivative, a 2-hydroxyphenyltriazine derivative, a hindered amine derivative, and a mixture thereof to the polyimide or polyamide-imide copolymer to prepare a polyimide-based composition; and a step of applying the composition prepared above to a glass substrate to prepare a polyimide-based film. Specifically, the above polyimide or polyamide-imide copolymer can be prepared by polymerizing a diamine and a dianhydride, without being particularly limited thereto.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

Preparation example 1: synthesis of polyimide precursor

After dimethyl acetamide was charged at normal temperature while nitrogen was passed through a temperature-adjustable stirred reactor connected to a nitrogen injection device and a dropping funnel, 1 mol% of a fluorine-based Diamine monomer (2,2' -Bis (trifluoromethyl) benzidine) was dissolved. After 0.8 mol% of 2,2-Bis (3, 4-dicarboxyphenyl) -hexafluoropropane dianhydride (2,2-Bis (3, 4-anhydroxyphenyl) -hexafluoro monomer was charged therein and reacted as an Anhydride (Anhydride) monomer, 0.2 mol% of 4,4 '-Oxydiphthalic Anhydride (ODPA, 4,4' -Oxydiphthalic Anhydride) was added thereto and stirred for a predetermined time after a predetermined time.

Preparation example 2: synthesis of polyimide copolymer

Pyridine (pyridine) and Acetic Anhydride (Acetic Anhydride) are added as a catalyst and a dehydrating agent to the polyimide precursor solution synthesized above, and then the temperature is raised to 70 ℃, followed by reaction for 1 hour, and then cooling to room temperature. The precipitate was solidified after being mixed with methanol (MeOH) and distilled water (3: 1). After thorough washing in MeOH, it was thoroughly dried in an 80-degree vacuum oven for 6 hours. The obtained polyimide solid was dispersed in a dimethylacetamide solution. Stirring was carried out sufficiently to avoid remaining solid components, and then filtration was carried out to remove foreign matters and unreacted phases. The filtrate was dried thoroughly in an oven to obtain a white solid. Finally, the white solid was dissolved in dimethylacetamide at a concentration of 13 weight percent.