WO2019073970A1

WO2019073970A1 - Polyimide resin composition, and polyimide film and production method therefor

Info

Publication number: WO2019073970A1
Application number: PCT/JP2018/037601
Authority: WO
Inventors: 翔人番家; 康孝近藤; 裕之後; 多和田　誠
Original assignee: 株式会社カネカ
Priority date: 2017-10-11
Filing date: 2018-10-09
Publication date: 2019-04-18

Abstract

A polyimide film comprising a polyimide resin and a triazine-based compound. The triazine-based compound is a 2,4,6-triphenyl-1,3,5-triazine derivative in which only one of the three benzene rings bonded to the triazine ring has a hydroxyl group. The polyimide film is produced from a polyimide resin composition which comprises a polyimide resin, the triazine-based compound, and a solvent. Since the polyimide resin composition contains the given triazine compound, the polyimide film is highly transparent and has little warpage.

Description

Polyimide resin composition, polyimide film and method for producing the same

The present invention relates to a polyimide resin composition containing a soluble polyimide, a transparent polyimide film, and a method for producing the same.

With the rapid progress of electronic devices such as displays, touch panels, and solar cells, thinner, lighter, and more flexible devices are required. In response to these requirements, replacement of glass materials used for substrates, cover windows, etc. with plastic film materials is being considered. In particular, in applications where high heat resistance, dimensional stability at high temperature, and high mechanical strength are required, application of a polyimide film as a glass substitute material is being studied.

Common polyimides are colored in yellow or brown and show no solubility in organic solvents. As a method for imparting visible light transparency and solubility to polyimide, introduction of an alicyclic structure, introduction of a bent structure, introduction of a fluorine substituent, and the like are known. By using such a polyimide, a transparent, less colored polyimide film can be obtained.

A polyimide film is generally produced by a method in which a polyamide acid solution, which is a polyimide precursor, is applied in the form of a film on a substrate, the solvent is removed by heating, and the polyamic acid is dehydrated and cyclized to be imidized ( For example, Patent Document 1). A soluble polyimide can also be manufactured by the method of apply | coating a polyimide resin on a board | substrate and removing a solvent (for example, patent document 2).

In the case of performing imidization of polyamic acid together with film formation in the production of a polyimide film, an imidization catalyst and a dehydrating agent for imidization, water generated by dehydration of polyamic acid, and the like easily remain in the film. Since heat treatment at a high temperature is required for imidization, the film tends to be colored yellow even when a highly transparent polyimide resin material is used.

In the case of producing a polyimide film using a polyimide resin solution, first, an imidization catalyst and a dehydrating agent are added to a polyamic acid solution to carry out imidization to isolate the polyimide resin. The isolated polyimide resin has a small amount of residual imidization catalyst, dehydrating agent, unreacted monomer component and the like. Impurities can be further reduced by washing the isolated resin. Since a solution obtained by dissolving the isolated polyimide resin in a solvent is applied in the form of a film on a substrate, high temperature heating for imidization is not required, and a film with high transparency and little coloration can be obtained.

WO2015 / 125895 JP 2004-258544 A

From the above viewpoint, a method using a polyimide resin solution is preferable for producing a transparent polyimide film. However, when the imidation is performed by adding an imidation catalyst and a dehydrating agent to the polyamic acid solution, the viscosity of the solution may be rapidly increased to cause gelation. Therefore, even when the polyimide resin itself is soluble, isolation of the polyimide resin from the polyamic acid solution is not easy, and a method of performing imidization after applying the polyamic acid solution in a film form as described in Patent Document 1 is It may be adopted.

That is, for the production of a film using a polyimide resin solution, in addition to the fact that the polyimide resin itself has solubility in a solvent, it is required that gelation does not occur upon imidation from a polyamic acid solution, It is necessary to design molecules in light of such characteristics. Patent Document 2 shows an example in which a transparent polyimide film (retardation film) having a thickness of 7 μm is formed on a substrate using a fluorine-containing aromatic polyimide resin. However, there are few examples of producing a transparent polyimide film having a large film thickness applicable to a substrate, a cover window, etc. by a film forming method from a polyimide resin solution.

When a thick transparent polyimide film is produced using a soluble polyimide resin that does not cause gelation during imidization from a polyamic acid solution, the film may be warped or curled. In particular, when a polyimide resin solution is applied onto a substrate and the film after drying removal of the solvent is peeled off from the substrate, warpage or curl of the film tends to be large, and handling may be difficult. Moreover, when the thickness of a polyimide film becomes large, it is easy to produce coloring accompanying increase of light absorption.

In view of the said subject, this invention aims at provision of the transparent polyimide film with small curvature and little coloring.

The present invention is based on the finding that, by adding a specific triazine compound to a polyimide resin, the warp of the polyimide film can be suppressed, and a polyimide film having high transparency and little coloring can be obtained.

The polyimide resin composition of the present invention comprises a solvent-soluble polyimide resin, a triazine compound represented by the following general formula (I), and a solvent.

R is any substituent other than a hydroxyl group, and a plurality of R may be the same or different. p is an integer of 0 to 4, and q and r are each independently an integer of 0 to 5.

The polyimide resin composition preferably contains 0.1 to 10 parts by weight of the above triazine compound with respect to 100 parts by weight of the polyimide resin. As a solvent of a polyimide resin composition, a ketone system solvent is used, for example.

The polyimide resin has an acid dianhydride-derived structure and a diamine-derived structure. The polyimide resin preferably contains an alicyclic acid dianhydride as an acid dianhydride component, and more preferably contains a fluorine-containing aromatic acid dianhydride in addition to the alicyclic acid dianhydride. The polyimide resin preferably contains a sulfonyl group-containing diamine as a diamine component, and more preferably contains a fluorine-containing aromatic diamine in addition to the sulfonyl group-containing diamine. As the sulfonyl group-containing diamine, for example, 3,3'-diaminodiphenyl sulfone is used.

A polyimide film is obtained by apply | coating said resin composition to a film form on a board | substrate, and removing a solvent by heating. The thickness of the polyimide film is, for example, 20 μm or more. The degree of yellowness of the polyimide film is preferably 3.5 or less. In the polyimide film, the ratio A ₃₈₀ / A ₄₀₀ of the absorbance A ₄₀₀ at a wavelength of ₄₀₀ nm to the absorbance A ₃₈₀ at a wavelength of 380 nm is preferably 3 or more. The absorbance at a wavelength of 400 nm of the polyimide film is preferably 0.3 or less per 100 μm of thickness. In applications such as a front window of a display, the pencil hardness of the polyimide film is preferably 3 H or more.

By using the polyimide resin composition of this invention, curvature of a polyimide film can be suppressed and productivity and the handleability of the film by roll to roll can be improved. The triazine-based compound contained in the polyimide resin composition has ultraviolet absorptivity and little absorption of visible light. Therefore, according to the present invention, a polyimide film with small warpage, high transparency and little coloring can be obtained.

[Polyimide resin composition]
A polyimide resin composition is used for preparation of a transparent polyimide film. The polyimide resin composition contains a solvent-soluble polyimide resin and an additive in a solvent.

The solvent solubility of a polyimide refers to the solubility at the time of imidation by dehydrating cyclization of polyamic acid, and the solubility to the solvent of polyimide resin itself. Having solubility at the time of imidization means that no solid matter or turbidity occurs when imidation is performed by adding a dehydrating agent, an imidation catalyst and the like to a polyamic acid solution. The solubility of the polyimide resin itself means that no solid or turbidity occurs when the polyimide resin is dissolved in a solvent used for preparation of a solution (dope) for film formation. The soluble polyimide resin has the above characteristics when the solid content concentration of the polyamic acid solution and the polyimide solution is preferably 10% by weight or more, more preferably 15% by weight or more, and still more preferably 20% by weight or more.

<Polyimide resin>
A polyimide resin is generally obtained by dehydrating and cyclizing a polyamic acid obtained by condensation of a tetracarboxylic acid dianhydride (hereinafter may be simply referred to as "acid dianhydride") with a diamine. That is, the polyimide has an acid dianhydride-derived structure and a diamine-derived structure. The polyimide resin showing transparency and solvent solubility preferably contains an alicyclic structure or a fluorine atom in at least one of acid dianhydride and diamine, and more preferably, it is fat in both acid dianhydride and diamine. It contains a cyclic structure or a fluorine atom.

The weight average molecular weight of the polyimide is preferably 5,000 to 500,000, more preferably 10,000 to 300,000, and still more preferably 30,000 to 200,000. When the weight average molecular weight is within this range, sufficient mechanical properties are likely to be obtained. The molecular weight in the present specification is a value in terms of polyethylene oxide (PEO) by gel permeation chromatography (GPC). The molecular weight can be adjusted by the molar ratio of diamine to acid dianhydride, reaction conditions, and the like.

(Acid dianhydride)
The solvent-soluble and transparent polyimide preferably contains, as an acid dianhydride component, a cycloaliphatic acid dianhydride and / or a fluorine-containing aromatic acid dianhydride. In order to obtain a highly transparent and less colored polyimide film, it is preferable to use a cycloaliphatic acid dianhydride as the acid dianhydride.

As alicyclic acid dianhydride, 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentane tetracarboxylic acid dianhydride, 1,2,4,5 1-cyclohexanetetracarboxylic acid dianhydride, 1,1'-bicyclohexane-3,3 ', 4,4'-tetracarboxylic acid-3,4,3', 4'-dianhydride. Among them, since a polyimide excellent in transparency and mechanical strength can be obtained, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and / or 1,2,4,5-cyclohexanetetra can be used as the acid dianhydride. Preference is given to using carboxylic acid dianhydrides, particular preference to 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride.

As the fluorine-containing aromatic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3,3,3-hexafluoropropane dianhydride etc. are mentioned. By using a fluorine-containing aromatic acid dianhydride as the acid dianhydride component in addition to the alicyclic acid dianhydride, the solubility of the polyimide resin is improved, and in particular, the gelation at the time of imidization is suppressed Tend.

The polyimide resin may contain components other than the alicyclic acid dianhydride and the fluorine-containing aromatic acid dianhydride as the acid dianhydride component. As acid dianhydrides other than alicyclic acid dianhydrides and fluorine-containing aromatic acid dianhydrides, pyromellitic dianhydride, 1,2,5,6-naphthalene tetracarboxylic acid dianhydride, 2, Aromatic tetracarboxylic acid dianhydrides in which four carbonyls are bonded to one aromatic ring such as 3,6,7-naphthalenetetracarboxylic acid dianhydride; 2,2-bis [4- (3,4-) Dicarboxyphenoxy) phenyl] propane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] hexafluoropropane dianhydride, 2,2-bis (4-hydroxyphenyl) propane dihydrate Benzoate-3,3 ', 4,4'-tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic acid Acid dianhydride 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride, 3,4'-oxydiphthalic anhydride, 4,4'- Aromatic tetracarboxylic acid dianhydrides in which two carbonyl groups are bonded to different aromatic rings such as oxydiphthalic anhydride and 3,3 ', 4,4'-diphenyl sulfone tetracarboxylic acid dianhydride Be

From the viewpoint of transparency and solvent solubility of the polyimide resin, the total of the alicyclic acid dianhydride and the fluorine-containing aromatic acid dianhydride is at least 60 mol% in the total 100 mol% of the acid dianhydride component. preferable. The total of the alicyclic acid dianhydride and the fluorine-containing aromatic acid dianhydride out of the total 100 mol% of the acid dianhydride component is at least 65 mol%, at least 70 mol%, at least 75 mol%, 80 mol %, 85 mol% or more, 90 mol% or more, or 95 mol% or more. As an acid dianhydride component, in addition to a cycloaliphatic acid dianhydride and / or a fluorine-containing aromatic acid dianhydride, an aromatic tetracarboxylic acid dicarbonyl in which two carbonyl groups are bonded to different aromatic rings By using the anhydride, heat resistance and mechanical strength may be able to be improved without impairing the transparency and solubility of the polyimide resin.

From the viewpoint of achieving both the transparency and the solvent solubility of the polyimide resin, the content of the alicyclic acid dianhydride is preferably 20 to 95% by mole in the total 100% by mole of the acid dianhydride component. The content of the alicyclic acid dianhydride in the total 100 mol% of the acid dianhydride component is 25 mol% or more, 30 mol% or more, 35 mol% or more, 40 mol% or more, 45 mol% or more or It may be 50 mol% or more. The content of the alicyclic dianhydride in the total 100 mol% of the acid dianhydride component is 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, Or 65 mol% or less. The content of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride is preferably in the above range, since a polyimide resin having excellent transparency and mechanical strength and excellent solubility can be obtained.

From the viewpoint of solubility of the polyimide resin, the content of the fluorine-containing aromatic acid dianhydride is at least 5 mol%, at least 10 mol%, at least 15 mol%, of the total 100 mol% of the acid dianhydride component It may be 20 mol% or more, or 25 mol% or more. Containing 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride because a polyimide resin excellent in solubility and transparency can be obtained The amount is preferably in the above range.

(Diamine)
It is preferable that the polyimide which has solvent solubility and transparency contains a fluorine-containing aromatic diamine as a diamine component.

As the fluorine-containing aromatic diamine, 1,4-diamino-2-fluorobenzene, 1,4-diamino-2,3-difluorobenzene, 1,4-diamino-2,5-difluorobenzene, 1,4- Diamino-2,6-difluorobenzene, 1,4-diamino-2,3,5-trifluorobenzene, 1,4-diamino, 2,3,5,6-tetrafluorobenzene, 1,4-diamino-2 -(Trifluoromethyl) Hensen, 1,4-diamino-2,3-bis (trifluoromethyl) benzene, 1,4-diamino-2,5-bis (trifluoromethyl) benzene, 1,4-diamino- 2,6-Bis (trifluoromethyl) benzene, 1,4-diamino-2,3,5-tris (trifluoromethyl) benzene, 1,4-diamino-2,3,5,6- Trakis (trifluoromethyl) benzene, 2-fluorobenzidine, 3-fluorobenzidine, 2,3-difluorobenzidine, 2,5-difluorobenzidine, 2,6-difluorobenzidine, 2,3,5-trifluorobenzidine, 2 , 3,6-trifluorobenzidine, 2,3,5,6-tetrafluorobenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2,3'-difluorobenzidine, 2,2 ', 3-trifluorobenzidine, 2,3,3'-trifluorobenzidine, 2,2 ', 5-trifluorobenzidine, 2,2', 6-trifluorobenzidine, 2,3 ', 5-trifluorobenzidine, 2,3 ', 6, -Trifluorobenzidine, 2,2', 3,3'-tetrafluorobenzidine, 2,2 ′, 5,5′-tetrafluorobenzidine, 2,2 ′, 6,6′-tetrafluorobenzidine, 2,2 ′, 3,3 ′, 6,6′-hexafluorobenzidine, 2,2 ′ , 3,3 ′, 5,5 ′, 6,6′-octafluorobenzidine, 2- (trifluoromethyl) benzidine, 3- (trifluoromethyl) benzidine, 2,3-bis (trifluoromethyl) benzidine, 2,5-bis (trifluoromethyl) benzidine, 2,6-bis (trifluoromethyl) benzidine, 2,3,5-tris (trifluoromethyl) benzidine, 2,3,6-tris (trifluoromethyl) Benzidine, 2,3,5,6-tetrakis (trifluoromethyl) benzidine, 2,2'-bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoro) (Methyl) benzidine, 2,3'-bis (trifluoromethyl) benzidine, 2,2 ', 3-bis (trifluoromethyl) benzidine, 2,3,3'-tris (trifluoromethyl) benzidine, 2,2 ', 5-tris (trifluoromethyl) benzidine, 2,2', 6-tris (trifluoromethyl) benzidine, 2,3 ', 5-tris (trifluoromethyl) benzidine, 2,3', 6,- Tris (trifluoromethyl) benzidine, 2,2 ', 3,3'-tetrakis (trifluoromethyl) benzidine, 2,2', 5,5'-tetrakis (trifluoromethyl) benzidine, 2,2 ', 6 , 6′-tetrakis (trifluoromethyl) benzidine and the like. From the viewpoint of obtaining a polyimide excellent in transparency and mechanical strength, as the fluorine-containing aromatic diamine, fluoroalkyl-substituted benzidine is preferable. Among them, bis (trifluoromethyl) benzidine such as 2,2'-bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoromethyl) benzidine and the like is preferable, and 2,2'-bis (trifluoromethyl) Benzidine is particularly preferred.

By using a sulfonyl group-containing diamine as the diamine component in addition to the fluorine-containing aromatic diamine, the mechanical strength of the polyimide resin tends to be improved. As the sulfonyl group-containing diamine, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4 4- (4-aminophenoxy) phenyl] sulfone, 4,4'-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenyl sulfone, 4,4'-bis [4- (4- (4-amino-α) Diphenyl sulfone derivatives such as amino phenoxy) phenoxy] diphenyl sulfone. Among them, 3,3'-diaminodiphenyl sulfone is particularly preferable because the mechanical strength can be improved without impairing the transparency and solubility of the polyimide resin.

The polyimide resin may contain components other than the fluorine-containing aromatic diamine and the sulfonyl group-containing diamine as a diamine component. Diamines in which two amino groups are bonded to one aromatic ring such as p-phenylenediamine, m-phenylenediamine and o-phenylenediamine as diamines other than fluorine-containing aromatic diamine and sulfonyl group-containing diamine; diaminodiphenyl ether , Aromatic diamines to which amino groups of different aromatic rings such as diaminodiphenyl sulfide, diaminobenzophenone, diaminodiphenylalkane, bis (aminobenzoyl) benzene and the like are bonded; alicyclic diamines such as diaminocyclohexane and isophorone diamine can be mentioned. .

From the viewpoint of transparency and solvent solubility of the polyimide resin, the content of the fluorine-containing aromatic diamine is 25 mol% or more, 30 mol% or more, 35 mol% or more, and 40 mol% of the total 100 mol% of the diamine component It may be 45 mol% or more, 50 mol% or more, 55 mol% or more, or 60 mol% or more. The content of 2,2'-bis (trifluoromethyl) benzidine is preferably in the above range, since a polyimide resin having excellent solubility and transparency can be obtained.

From the viewpoint of improving the transparency and mechanical strength of the polyimide resin, the content of the sulfonyl group-containing diamine is preferably 10 to 75% by mole in the total 100% by mole of the diamine component of the polyimide. The content of the sulfonyl group-containing diamine in the total 100 mol% of the diamine component of the polyimide may be 15 mol% or more, 20 mol% or more, or 25 mol% or more. The content of the sulfonyl group-containing diamine in the total 100 mol% of the diamine component of the polyimide is 70 mol% or less, 65 mol% or less, 60 mol% or less, 55 mol% or less, 50 mol% or less, 45 mol% or less , 40 mol% or less or 35 mol% or less. In particular, the content of 3,3'-diaminodiphenyl sulfone is preferably in the above range.

From the viewpoint of transparency and solubility of the polyimide resin, the total of the fluorine-containing aromatic diamine and the sulfonyl group-containing diamine is preferably 60 mol% or more in 100 mol% of the total of the diamine component. The total of the fluorine-containing aromatic diamine and the sulfonyl group-containing diamine in the total 100 mol% of the diamine component is at least 65 mol%, at least 70 mol%, at least 75 mol%, at least 80 mol%, at least 85 mol%, 90 It may be mol% or more, or 95 mol% or more.

(Synthesis of polyamic acid)
The polyamic acid is obtained, for example, by reacting an acid dianhydride with a diamine in an organic solvent. The acid dianhydride and the diamine are preferably used in approximately equimolar amounts (molar ratio of 95: 100 to 105: 100). In order to suppress the ring opening of acid dianhydride, after dissolving a diamine in a solvent, the method of adding acid dianhydride is preferable. In the case of adding a plurality of diamines or a plurality of acid dianhydrides, one may be added at once, or two or more divided additions may be added. The polyamic acid solution is usually obtained at a concentration of 5 to 35% by weight, preferably 10 to 30% by weight.

For the polymerization of the polyamic acid, diamines and acid dianhydrides as raw materials, and an organic solvent capable of dissolving the polyamic acid which is a polymerization product can be used without particular limitation. Specific examples of the organic solvent include urea solvents such as methyl urea and N, N-dimethylethyl urea; sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone and tetramethyl sulfone; N, N-dimethyl acetamide, N, N- Amide solvents such as dimethylformamide, N, N'-diethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone and hexamethylphosphoric acid triamide; halogenated alkyl solvents such as chloroform and methylene chloride; benzene, toluene and the like And aromatic solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, p-cresol methyl ether and the like. Among these, dimethylacetamide, dimethylformamide or N-methylpyrrolidone is preferably used because of excellent polymerization reactivity and solubility of polyamic acid.

(Imidation)
Polyimide is obtained by dehydrating cyclization of polyamic acid. For imidation with a solution, a chemical imidation method in which a dehydrating agent, an imidation catalyst and the like are added to a polyamic acid solution is suitable. The polyamic acid solution may be heated to accelerate the imidization process.

A tertiary amine is used as the imidization catalyst. Among them, heterocyclic tertiary amines such as pyridine, picoline, quinoline and isoquinoline are preferable. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic acid anhydride, butyric acid anhydride, benzoic acid anhydride, trifluoroacetic acid anhydride and the like are used. The addition amount of the imidization catalyst is preferably 0.5 to 5.0 molar equivalents, more preferably 0.6 to 2.5 molar equivalents, and more preferably 0.7 to 2.0 moles with respect to the amide group of the polyamic acid. An equivalent is more preferred. The amount of the dehydrating agent added is preferably 0.5 to 10.0 molar equivalents, more preferably 0.7 to 7.0 molar equivalents, and 1.0 to 5.0 molar equivalents with respect to the amide group of the polyamic acid. Is more preferred.

Even when the polyimide resin after imidization itself shows solubility in a solvent, the solution viscosity may be rapidly increased during chemical imidization of the polyamic acid solution, and gelation may occur. When the above-mentioned acid dianhydride component and diamine component are used, since the solubility at the time of imidization is high, gelation can be suppressed.

(Deposition of polyimide resin)
The polyimide solution obtained by the imidization of the polyamic acid can be used as it is as a film forming dope, but it is preferable to temporarily precipitate the polyimide resin as a solid. By depositing the polyimide resin as a solid, impurities and residual monomer components generated during polymerization of the polyamic acid, and the dehydrating agent and the imidation catalyst can be washed and removed. Therefore, a polyimide film excellent in transparency and mechanical properties can be obtained.

A polyimide resin precipitates by mixing a polyimide solution and a poor solvent. The poor solvent is preferably a poor solvent for a polyimide resin, which is miscible with the solvent in which the polyimide resin is dissolved, and includes water, alcohols and the like. Examples of alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol, triethylene glycol, 2-butyl alcohol, 2-hexyl alcohol, cyclopentyl alcohol, cyclohexyl alcohol, phenol, t-butyl alcohol and the like. Alcohols such as isopropyl alcohol, 2-butyl alcohol, 2-pentyl alcohol, phenol, cyclopentyl alcohol, cyclohexyl alcohol, t-butyl alcohol and the like are preferable, and isopropyl alcohol is particularly preferable, because ring opening of the polyimide hardly occurs.

Before mixing the polyimide resin solution and the poor solvent, the solid content concentration of the polyimide solution may be adjusted. The solid content concentration of the polyimide solution is preferably about 3 to 30% by weight. As a method of mixing the polyimide resin solution and the poor solvent, a method of putting the polyimide solution into the poor solvent solution, a method of putting the poor solvent into the polyimide solution, a method of simultaneously mixing the poor solvent and the polyimide solution, etc. It can be mentioned. The amount of the poor solvent is preferably equal to or more than that of the polyimide resin solution, more preferably 1.5 or more times by volume, and still more preferably 2 or more times by volume. Since a small amount of imidation catalyst, a dehydrating agent, etc. may remain in the deposited polyimide resin, it is preferable to wash with a poor solvent. It is preferable to remove the poor solvent by vacuum drying, hot air drying or the like after the deposition and washing.

<Triazine-based compounds>
The resin composition of the present invention contains a 2,4,6-triphenyl-1,3,5-triazine derivative represented by the following general formula (I) in addition to a soluble polyimide resin.

In the general formula (I), R is an optional substituent other than a hydroxyl group, and a plurality of R may be the same or different. p is an integer of 0 to 4, and q and r are each independently an integer of 0 to 5. In other words, the triazine compound used as an additive has a hydroxyl group at the 2-position of one benzene ring among the three benzene rings bonded to the 2-, 4- and 6-positions of the triazine ring, Is a triazine compound having no hydroxyl group on the two benzene rings of

Specific examples of the substituent R include an alkyl group, an alkoxy group, an alkoxyalkyl group, a hydroxyalkyl group, a hydroxyalkoxy group, a phenyl group and the like. The carbon number of these substituents is 1 to 20. The substituent may be linear or branched. These substituents may be those in which some or all of the alkyl or alkylene hydrogen atoms are halogen-substituted.

Specific examples of the above triazine compounds include 2,6-diphenyl-4- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine (commercially available as "TINUVIN 1577" manufactured by BASF), 2- (2-hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine (commercially available as BASF "TINUVIN 479" ), 2- [4,6-bis (1,1′-biphenyl-4-yl) -1,3-5-triazin-2-yl] -5- (2-ethylhexyl) oxy] phenol (as a commercial product) BASF “Tinuvin 1600”), 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-n-octyloxyphenyl) -1,3,5-Triazine (commercially available, "KEMISORB 102" manufactured by Chemipro Chemical, and "CYASORB UV-1164" manufactured by Sun Chemical Co., Ltd.), 2- (4,6-bis (2,4-dimethylphenyl) -1 Of 3,5-triazin-2-yl) -5-hydroxyphenyl and [(C _10-16 alkyloxy) methyl] oxirane (commercially available as BASF “TINUVIN 400”), 2- (2 Reaction product of 2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine with (2-ethylhexyl) -glycidic ester (commercially available as BASF Manufactured by "TINUVIN 405", and the like.

The above triazine compound is excellent in compatibility with the transparent polyimide resin. When the polyimide resin composition contains the above-mentioned triazine compound, warpage and curl of the polyimide film tend to be reduced. Therefore, the handling property at the time of manufacture of the polyimide film by roll to roll can be improved, and the productivity and the yield of a film can be improved. Moreover, since the curvature and curl of a polyimide film are small, the handling property at the time of formation of the element on a polyimide film, and the incorporation to a device improves.

Of the three benzene rings linked to the triazine ring, 2,4,6-triphenyl-1,3,5-triazine derivatives having a hydroxyl group on only one benzene ring have ultraviolet absorption and are visible The light absorptivity of the light short wavelength is small. Therefore, by adding the above-mentioned triazine compound to the polyimide resin, it is possible to manufacture a transparent polyimide film having a small degree of yellowness and little coloring, with high productivity. Moreover, since the above-mentioned triazine type compound also acts as an ultraviolet absorber, the polyimide film which is excellent in ultraviolet absorptivity can be obtained.

The addition amount of the triazine compound is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the polyimide resin, from the viewpoint of achieving both suppression of film warpage and maintenance of transparency. The content of the triazine compound with respect to 100 parts by weight of the polyimide resin is 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, It may be 0.7 parts by weight or more. The content of the triazine compound with respect to 100 parts by weight of the polyimide resin is 7 parts by weight, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2.5 parts by weight or less, or 2 parts by weight or less or 1.5 parts It may be less than part.

<Solvent>
A polyimide resin composition (solution) is prepared by dissolving the above-described polyimide resin and additives in a suitable solvent. The solvent is not particularly limited as long as it dissolves and dissolves the above-mentioned polyimide resin and additives, and, for example, urea solvents, sulfone solvents and amide solvents exemplified as organic solvents used for polymerization of polyamic acid And halogenated alkyl solvents, aromatic hydrocarbon solvents, ether solvents and the like. In addition to these, ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone and methyl cyclohexanone are also preferably used as a solvent for the polyimide resin composition. .

Among these, amide solvents, aromatic hydrocarbon solvents, or ketone solvents are preferable. Among them, ketone solvents are preferable because they have high solubility in both the polyimide resin and the triazine compound, low boiling point, and can improve the production efficiency of the polyimide film. The solvent of the polyimide resin composition preferably contains a ketone solvent. The amount of the ketone-based solvent is preferably 50 parts by weight or more, more preferably 70 parts by weight or more, and still more preferably 80 parts by weight or more in 100 parts by weight of the total amount of the solvent.

<Other ingredients>
The polyimide resin composition may contain resin components other than polyimide and additives other than triazine compounds. Examples of the additive include a crosslinking agent, a dye, a surfactant, a leveling agent, a plasticizer, and fine particles. The content of the polyimide resin is preferably 60 parts by weight or more, more preferably 70 parts by weight or more, and still more preferably 80 parts by weight or more based on 100 parts by weight of the solid content of the polyimide resin composition.

The solid content concentration and viscosity of the polyimide solution may be appropriately set according to the molecular weight of the polyimide, the thickness of the film, the film forming environment, and the like. The solids concentration is preferably 5 to 30% by weight, more preferably 8 to 25% by weight, and still more preferably 10 to 21% by weight. The viscosity at 25 ° C. is preferably 0.5 Pa · s to 60 Pa · s, more preferably 2 Pa · s to 50 Pa · s, and still more preferably 5 Pa · s to 40 Pa · s.

[Polyimide film]
<Method for producing polyimide film>
As a method of producing a polyimide film, a method of coating a substrate with a polyamic acid solution in a film form, drying and removing the solvent and imidizing the polyamic acid, and applying the polyimide resin solution in a film form on a substrate And the like. Since the polyimide resin used in the present invention is soluble, any method can be adopted. The latter method is preferable from the viewpoint of obtaining a highly transparent polyimide film with few residual impurities. In the latter method, the above-mentioned polyimide resin composition is used.

The thickness of the polyimide film is not particularly limited, and may be appropriately set according to the application. The thickness of the polyimide film is, for example, 5 μm or more. The thickness of the polyimide film is preferably 20 μm or more, more preferably 25 μm or more, and still more preferably 30 μm or more, from the viewpoint of imparting a self-supporting property to the polyimide film after peeling from the support. In applications where strength is required, such as a cover window material of a display, the thickness of the polyimide film may be 40 μm or more or 50 μm or more. The upper limit of the thickness of the polyimide film is not particularly limited, but from the viewpoint of flexibility and transparency, 200 μm or less is preferable, 150 μm or less is more preferable, and 100 μm or less is more preferable.

As a support which apply | coats film forming dope, a glass substrate, metal substrates, such as SUS, a metal drum, a metal belt, a plastic film etc. can be used. From the viewpoint of improving productivity, it is preferable to produce a film by roll-to-roll using an endless support such as a metal drum or a metal belt, a long plastic film, or the like as a support. When a plastic film is used as a support, a material which does not dissolve in a solvent for film formation dope may be appropriately selected, and as the plastic material, polyethylene terephthalate, polycarbonate, polyacrylate, polyethylene naphthalate or the like is used.

The polyimide resin composition is applied on a support, and the solvent is removed by drying to obtain a polyimide film. It is preferable to heat at the time of drying of a solvent. The heating temperature is not particularly limited, and is appropriately set at about room temperature to 250 ° C. The heating temperature may be raised stepwise.

The film after removal of the solvent by heating and drying the solution on the support has thermal history, residual stress and residual solvent amount on the A side of the film (air interface during application) and B side (substrate side during application). There is a difference in Peeling the film from the support releases the holding power of the support and tends to cause warpage or curling due to the difference in properties between the front and back of the film. In particular, when the thickness of the film is increased, the difference in the characteristics of the front and back is large, so the warp and the curl tend to be increased. If the film is warped or curled, conveyance by roll-to-roll becomes difficult, and the productivity and the handling property may be reduced. By using a resin composition containing a polyimide resin and the above-mentioned triazine compound, warpage and curl of the polyimide film tend to be reduced. Therefore, the productivity and the yield of the film by roll to roll can be improved.

<Characteristics of polyimide film>
It is preferable that the polyimide film used for a display etc. has low yellowness degree (YI). 3.5 or less is preferable and, as for the yellowness degree of a polyimide film, 3.0 or less is more preferable. The absorbance A _{400 at} a wavelength of 400 nm of the polyimide film is preferably 0.25 or less, more preferably 0.2 or less, and still more preferably 0.15 or less. The absorbance A _{400 at} a wavelength of 400 nm of the polyimide film is preferably 0.3 or less, more preferably 0.25 or less, and even more preferably 0.2 or less per 100 μm of thickness. When the polyimide film is required to have an ultraviolet shielding property, the absorbance A _{380 at} a wavelength of 380 nm is preferably 0.3 or more, more preferably 0.35 or more, still more preferably 0.4 or more, and particularly preferably 0.45 or more. The absorbance A _{380 at} a wavelength of 380 nm of the polyimide film is preferably 0.4 or more, more preferably 0.45 or more, and still more preferably 0.5 or more per 100 μm of thickness.

The light transmittance at a wavelength of 400 m of the polyimide film is preferably 55% or more, more preferably 60% or more, further preferably 65% or more, and particularly preferably 70% or more. When ultraviolet shielding properties are required for the polyimide film, the light transmittance at a wavelength of 380 nm is preferably 50% or less, more preferably 40% or less, still more preferably 35% or less, and particularly preferably 30% or less.

In the polyimide film, the ratio A ₃₈₀ / A ₄₀₀ of the absorbance A ₄₀₀ at a wavelength of ₄₀₀ nm to the absorbance A ₃₈₀ at a wavelength of 380 nm is preferably 3 or more, more preferably 3.5 or more, and 3.8 or more It is more preferably present, and particularly preferably 4 or more.

As described above, by using a predetermined triazine compound as an additive, it is possible to obtain a polyimide film having a high visible light transmittance, an excellent ultraviolet ray absorptivity, and suppressed warpage and curl. The content of the above triazine compound in the polyimide film is preferably 0.1 to 10% by weight. The content of the above triazine compound in the polyimide film is 0.2% by weight or more, 0.3% by weight or more, 0.4% by weight or more, 0.5% by weight or more, 0.6% by weight or more, or 0 .7% by weight or more. The content of the above-mentioned triazine compound in the polyimide film is 7 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2.5 wt% or less or 2 wt% or less or 1.5 wt% It may be

The total light transmittance of the polyimide film is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more. 1.5% or less is preferable and, as for the haze of a polyimide film, 1% or less is more preferable.

The pencil hardness of the polyimide film is preferably HB or more, more preferably F or more, from the viewpoint of preventing damage to the film due to contact with the roll during roll-to-roll conveyance or contact between the films during winding. When the polyimide film is used as a cover window of a display or the like, the pencil hardness of the polyimide film is preferably 2H or more, more preferably 3H or more, since abrasion resistance to external contact is required. The mechanical strength of the polyimide film tends to be improved by using a diphenyl sulfone derivative such as 3,3'-diaminodiphenyl sulfone as the diamine component of the polyimide.

From the viewpoint of heat resistance, the glass transition temperature of the polyimide film is preferably 200 ° C. or more, more preferably 250 ° C. or more, and still more preferably 300 ° C. or more. The glass transition temperature is a temperature at which the loss tangent shows a maximum in dynamic viscoelastic analysis (DMA).

The polyimide film preferably has a small warpage. Specifically, 10 mm or less is preferable, 5 mm or less is more preferable, and 3 mm or less is the warp of the film which has been cut into a size of 10 cm × 10 cm and left to stand at 23 ° C. 55% RH for 1 day. More preferable.

<Use of polyimide film>
The polyimide film of the present invention is suitably used as a display material because of its small yellowness and high transparency. In particular, a polyimide film having high mechanical strength is used as a surface member such as a cover window of a display. The polyimide film containing the above-mentioned triazine-based compound has an ultraviolet shielding property, so when used as a cover window, the amount of ultraviolet rays reaching display materials such as organic EL elements and polarizing plates is reduced to increase the height of the display. Contribute to durability and long life. In practical use, the polyimide film of the present invention may be provided with an antistatic layer, an easily adhesive layer, a hard coat layer, an antireflective layer and the like on the surface.

Hereinafter, the present invention will be more specifically described based on examples and comparative examples. The present invention is not limited to the following examples.

[Polyimide synthesis]
Synthesis Example 1
In a 500 mL separable flask, 137.76 g of N, N-dimethylformamide (DMF) was charged, and the mixture was stirred under a nitrogen atmosphere. There, 13.04 g of 2,2'-bis (trifluoromethyl) benzidine (TFMB), 4.33 g of 3,3'-diaminodiphenyl sulfone (3,3'-DDS), 1,2,3,4- 5.70 g of cyclobutanetetracarboxylic acid dianhydride (CBDA), 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride (6FDA) 12.92 g and 26.24 g of acetic acid are sequentially added, and reacted by stirring under nitrogen atmosphere for 5 hours to give a solid content concentration of 18% and a viscosity of 200 poise at 23 ° C. of a polyamic acid (polyimide precursor) solution I got

13.81 g of pyridine as an imidization catalyst was added to the polyimide precursor solution and stirred, 17.82 g of acetic anhydride was added, stirred at 120 ° C. for 2 hours, and cooled to room temperature to obtain a polyimide solution. While stirring the solution, 1 L of isopropyl alcohol (IPA) was added at a rate of 2 to 3 drops / sec to precipitate the polyimide. After that, suction filtration was performed using a Kiriyama funnel, and washing was performed with 500 g of IPA. After washing with IPA was repeated three times, it was dried in an oven set at 120 ° C. for 12 hours to obtain a white polyimide powder (polyimide resin 1).

Synthesis Example 2
The raw materials and charges in the synthesis of polyamic acid are changed to DMF 137.76, TFMB 18.00 g, CBDA 5.51 g, 6FDA 12.49 g, and acetic acid 26.24 g, the amount of pyridine in imidization is 13.34 g, acetic anhydride The amount was changed to 17.22 g. A white polyimide powder (polyimide resin 2) was obtained in the same manner as in Synthesis Example 1 except for the above.

Synthesis Example 3
The raw materials and charges in the synthesis of polyamic acid are changed to DMF 137.60, TFMB 15.08 g, 6FDA 20.92 g, and acetic acid 26.24 g, the amount of pyridine in imidization is 11.18 g, and the amount of acetic anhydride is 14. It was changed to 42g. A white polyimide powder (polyimide resin 3) was obtained in the same manner as in Synthesis Example 1 except for the above.

The compositions (molar ratios of acid dianhydride and diamine) of the polyimide resins 1 to 3 obtained in Synthesis Examples 1 to 3 are shown in Table 1.

[Preparation of polyimide film]
(Preparation of polyimide solution)
The polyimide resins and additives obtained in Synthesis Examples 1 to 3 were dissolved in methyl ethyl ketone with the composition shown in Table 2 to obtain solutions (compositions 1 to 18) having a polyimide resin concentration of 16% by weight. The details of the additives in Table 2 are as follows.

Kemisorb 102 (manufactured by Chemipro Chemical Industries): 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-n-octyloxyphenyl) -1,3,5-triazine;

Tinuvin 1600 (manufactured by BASF): 2- [4,6-bis (1,1'-biphenyl-4-yl) -1,3-5-triazin-2-yl] -5- (2-ethylhexyl) oxy] phenol ;

Tinuvin 460 (manufactured by BASF): 2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3-5-triazine;

SEESORB 151 (manufactured by Cipro Chemical Industries): 1,4-bis (4-benzoyl-3-hydroxyphenyl) -butane;
SEESORB 706 (manufactured by Cipro Chemical Industries): 2- [2-hydroxy-3- (4,5,6,7-tetrahydro-1,3-dioxo-1H-isoindol-2-ylmethyl) -5-methylphenyl] -2H -Benzotriazole;
KEMISORB 279 (manufactured by Chemipro Chemical Industries): 2,2′-methylenebis [6- (benzotriazol-2-yl) -4-t-octylphenol].

(Production of film)
The above solution is applied to an alkali free glass plate using a comma coater, and sequentially dried at 40 ° C. for 10 minutes, 50 ° C. for 20 minutes, 70 ° C. for 10 minutes, 150 ° C. for 30 minutes, and 170 ° C. for 30 minutes Then, it was peeled from the non-alkali glass plate to obtain a polyimide film having a thickness of 80 μm. Incidentally, for the compositions 8 to 10, film formation was not carried out because a clear solution could not be obtained.

[Evaluation]
(Warpage of film)
The polyimide film was cut into a square of 10 cm square, and was allowed to stand in an environment of 23 ° C. and 55% RH for 1 day to control the humidity. The film is placed on a horizontal table with the B side of the film (the surface on the glass plate side at the time of application) facing up, and the maximum value of the warp (distance from the table to the film) is measured by a height gauge made by MITUTOYO. It measured using HDS-H30C.

(Light transmittance and absorbance at wavelengths of 380 nm and 400 nm)
The transmission spectrum at 200 to 800 nm was measured using an ultraviolet visible near infrared spectrophotometer (V-650) manufactured by JASCO Corporation, and the transmittance and the absorbance at 380 nm and 400 nm were determined. The absorbance A and the transmittance T (%) have a relationship of A = −log ₁₀ T.

(Total light transmittance and haze)
It was measured by a method described in JIS K 7105-1981 using an integrating sphere-type haze meter 300A manufactured by Nippon Denshoku Kogyo.

(Yellow)
It measured by the method of JISK7373-2006 using HANDY COLORIMETER NR-3000 made from Nippon Denshoku Industries.

(Pencil hardness)
The pencil hardness of the film was measured by the "8.4.1 pencil scratching test" of JIS K-5400-1990.

(Glass-transition temperature)
Dynamic viscoelasticity measurement was performed with a measuring jig interval of 20 mm and a frequency of 5 Hz using DMS-200 manufactured by Seiko Instruments Inc., and the temperature at which the loss tangent (tan δ) became a maximum was taken as the glass transition temperature.

The composition of the polyimide resin composition and the evaluation results of the characteristics of the film are shown in Table 2.

The film produced from the solution (composition 7) of the polyimide resin 1 containing no additive had a warp of 20 mm, whereas the composition 1 to 6 using the solution to which the triazine compound was added caused the film to warp Was reduced to 3 mm. Also in the compositions 11 to 14 using the polyimide resin 2 and the compositions 15 to 18 using the polyimide resin 3, the warpage of the film was reduced by the addition of the triazine compound.

In the composition 8 using the benzophenone type compound as the additive, and the composition 9 and the composition 10 using the benzotriazole type compound, the compatibility between the additive and the solvent and / or the resin is insufficient, and a transparent film is obtained. It was not done.

By using a triazine compound as an additive, the transmittance at a wavelength of 380 nm of the polyimide film tends to decrease (absorbance increases). In the compositions 1 to 4, as the addition amount of the triazine compound is larger, the transmittance at 380 nm is smaller. From these results, it is understood that addition of the triazine compound to the polyimide resin can impart ultraviolet absorptivity in addition to the reduction of the warpage of the film.

Composition 6, Composition 13 using Tinuvin 460 (2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3-5-triazine) as an additive In the composition 17, the transmittance at a wavelength of 400 nm was significantly reduced. On the other hand, when Kemisorb 102 (2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-n-octyloxyphenyl) -1,3,5-triazine) is used as an additive. , And Tinuvin 1600 (2- [4,6-bis (1,1′-biphenyl-4-yl) -1,3-5-triazin-2-yl] -5- (2-ethylhexyl) oxy] phenol) When used, the decrease in transmittance at a wavelength of 400 nm was slight. From these results, it is suggested to add a 2,4,6-triphenyl-1,3,5-triazine derivative having a hydroxyl group only on one of three benzene rings bonded to a triazine ring to a polyimide resin. Thus, it can be seen that a transparent polyimide film having small warpage, little coloring, and ultraviolet absorption is obtained.

In particular, a film using Resin 1 containing an alicyclic dianhydride and a fluorine-containing aromatic acid dianhydride as an acid dianhydride component and containing a sulfonyl group-containing diamine and a fluorine-containing aromatic diamine as a diamine component is In addition to high pencil hardness and high transparency, mechanical strength is also excellent, and application as a transparent member disposed on the surface of a device such as a cover window can be expected.

Claims

Polyimide resin composition comprising a solvent-soluble polyimide resin, a triazine compound represented by the following general formula (I), and a solvent:

R is an arbitrary substituent other than a hydroxyl group, and a plurality of Rs may be the same or different; p is an integer of 0 to 4; q and r are each independently an integer of 0 to 5;
The polyimide resin composition according to claim 1, wherein the polyimide resin has an acid dianhydride-derived structure and a diamine-derived structure, and contains an alicyclic acid dianhydride as the acid dianhydride.
The polyimide resin composition according to claim 2, wherein the polyimide resin further contains a fluorine-containing aromatic acid dianhydride as the acid dianhydride.
The polyimide resin composition according to claim 2, wherein the polyimide resin contains a sulfonyl group-containing diamine as the diamine.
The polyimide resin composition according to claim 4, wherein the sulfonyl group-containing diamine is 3,3'-diaminodiphenyl sulfone.
The polyimide resin composition according to claim 4 or 5, further comprising a fluorine-containing aromatic diamine as the diamine.
The polyimide resin composition according to any one of claims 1 to 6, which contains 0.1 to 10 parts by weight of the triazine compound with respect to 100 parts by weight of the polyimide resin.
The polyimide resin composition according to any one of claims 1 to 7, wherein the solvent comprises a ketone solvent.
A method for producing a polyimide film, comprising applying the polyimide resin composition according to any one of claims 1 to 8 in the form of a film on a substrate and removing the solvent by heating.
A polyimide film comprising a polyimide resin and a triazine compound represented by the following general formula (I), having a thickness of 20 μm or more and a yellowness of 3.5 or less:

R is an arbitrary substituent other than a hydroxyl group, and a plurality of Rs may be the same or different; p is an integer of 0 to 4; q and r are each independently an integer of 0 to 5;
The polyimide film according to claim 10, wherein the polyimide resin has an acid dianhydride-derived structure and a diamine-derived structure, and contains an alicyclic acid dianhydride as the acid dianhydride.
The polyimide film according to claim 11, wherein the polyimide resin further contains a fluorine-containing aromatic acid dianhydride as the acid dianhydride.
The polyimide film according to claim 11, wherein the polyimide resin contains a sulfonyl group-containing diamine as the diamine.
The polyimide film according to claim 13, wherein the sulfonyl group-containing diamine is 3,3'-diaminodiphenyl sulfone.
The polyimide film according to claim 13, further comprising a fluorine-containing aromatic diamine as the diamine.
The polyimide film according to any one of claims 10 to 15, wherein 0.1 to 10 parts by weight of the triazine compound is contained with respect to 100 parts by weight of the polyimide resin.
The polyimide film according to any one of claims 10 to 16, wherein the ratio A 380 / A 400 of the absorbance A 400 at a wavelength of 400 nm and the absorbance A 380 at a wavelength of 380 nm is 3 or more.
The polyimide film according to any one of claims 10 to 17, wherein the absorbance at a wavelength of 400 nm is 0.3 or less per 100 μm of thickness.
The polyimide film according to any one of claims 10 to 18, which has a pencil hardness of 3H or more.