KR20220016917A - Polyimide resin and manufacturing method thereof, and polyimide film and manufacturing method thereof - Google Patents

Abstract

일반식 (1)에 있어서, R¹ 내지 R⁸은 각각 독립적으로, 수소 원자, 탄소 원자수 1 내지 20의 알킬기, 또는 탄소 원자수 1 내지 20의 퍼플루오로알킬기이며, R¹ 내지 R⁴ 중 하나 이상 및 R⁵ 내지 R⁸ 중 하나 이상은, 탄소 원자수 1 내지 20의 알킬기, 또는 탄소 원자수 1 내지 20의 퍼플루오로알킬기이다.The polyimide resin has an acid dianhydride-derived structure and a diamine-derived structure, and contains, as the diamine, 40 mol% or more and 100 mol% or less of fluoroalkyl-substituted benzidine with respect to 100 mol% of the diamine total amount, and as the acid dianhydride, the acid dianhydride total amount 100 mol % contains 40 mol% or more and 85 mol% or less of the acid dianhydride represented by the general formula (1), and 15 mol% or more and 60 mol% or less of the acid dianhydride having a cyclobutane structure.

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a perfluoroalkyl group having 1 to 20 carbon atoms, and among R ¹ to R ⁴ At least one and at least one of R ⁵ to R ⁸ is an alkyl group having 1 to 20 carbon atoms or a perfluoroalkyl group having 1 to 20 carbon atoms.

Description

Polyimide resin and manufacturing method thereof, and polyimide film and manufacturing method thereof

The present invention relates to a polyimide resin and a method for producing the same, a polyimide solution, and a polyimide film and a method for producing the same.

For weight reduction and flexibility of display devices, such as smartphones, the application of a polyimide film as a substitute material for glass conventionally used as a board|substrate or a surface protection material is examined. Common polyimides are colored yellow or brown and do not exhibit solubility in organic solvents, but polyimides of low color can be obtained by introducing an alicyclic structure or a fluoroalkyl group (for example, Patent Document 1).

Japanese Patent Laid-Open 2006-282884

The polyimide film obtained from the polyimide resin of patent document 1 does not have enough mechanical strength to use for the cover window etc. arrange|positioned on the outer surface of a device. An object of the present invention is to provide a polyimide resin and polyimide film that is soluble in a low-boiling solvent such as dichloromethane and is excellent in transparency and mechanical strength.

The polyimide resin according to an embodiment of the present invention has an acid dianhydride-derived structure and a diamine-derived structure, and as an acid dianhydride, an acid dianhydride represented by the general formula (1) and an acid dianhydride having a cyclobutane structure and fluoroalkyl substituted benzidine as the diamine.

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a perfluoroalkyl group having 1 to 20 carbon atoms, and among R ¹ to R ⁴ At least one and at least one of R ⁵ to R ⁸ is an alkyl group having 1 to 20 carbon atoms or a fluoroalkyl group having 1 to 20 carbon atoms.

As for the quantity of the acid dianhydride represented by General formula (1), 40-85 mol% is preferable with respect to 100 mol% of acid dianhydride whole quantity. As for the quantity of the acid dianhydride which has a cyclobutane structure, 15-60 mol% is preferable with respect to 100 mol% of acid dianhydride whole quantity. As for the quantity of fluoroalkyl-substituted benzidine, 40-100 mol% is preferable with respect to 100 mol% of diamine whole quantity.

As a specific example of the acid dianhydride represented by General formula (1), the compound represented by Formula (2) is mentioned.

Specific examples of the cyclobutane structure-containing acid dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride. Specific examples of the fluoroalkyl-substituted benzidine include 2,2'-bis(trifluoromethyl)benzidine.

The polyimide may contain the acid dianhydride component and the diamine component other than the above. As examples of acid dianhydrides other than the above, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3 ,3,3-hexafluoropropane dianhydride. Examples of diamines other than the above include diaminodiphenylsulfone.

A polyimide film is obtained by dissolving polyimide resin in a solvent, preparing a polyimide solution, apply|coating a polyimide solution on a base material, and removing a solvent. As a solvent which melt|dissolves a polyimide, low boiling point solvents, such as dichloromethane, are preferable.

40 micrometers or more may be sufficient as the thickness of a polyimide film. 3.0 or less may be sufficient as the yellowness of a polyimide film, 5.0 GPa or more may be sufficient as a tensile elasticity modulus, and H or more may be sufficient as pencil hardness.

The polyimide resin of the present invention is soluble in a low boiling point solvent such as dichloromethane, and since heating at a high temperature is not required to reduce the residual solvent, a polyimide film with high transparency is obtained. The polyimide resin of the present invention is soluble in a low boiling point solvent such as dichloromethane, and since heating at a high temperature is not required to reduce the residual solvent, a polyimide film with high transparency is obtained. Since the polyimide film of the present invention has high mechanical strength and high transparency even when the film thickness is large, it can be used as a substrate material for a display, a cover window material, or the like.

[Polyimide resin]

A polyimide is generally obtained by dehydrating and cyclizing the polyamic acid obtained by reaction of tetracarboxylic dianhydride (Hereinafter, it may simply describe "acid dianhydride") and diamine. That is, the polyimide has an acid dianhydride-derived structure and a diamine-derived structure. The polyimide resin of the present invention contains, as an acid dianhydride component, an acid dianhydride containing an ester group (bis anhydride trimellitic acid ester) and an acid dianhydride having an alicyclic structure, and contains a fluoroalkyl-substituted benzidine as a diamine component do.

<Acid dianhydride>

The polyimide of the present invention includes an ester group-containing acid dianhydride represented by the following general formula (1) as an acid dianhydride, and an alicyclic acid dianhydride having a cyclobutane structure.

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms. At least one of R ¹ to R ⁴ is a substituent other than a hydrogen atom, and at least one of R ⁵ to R ⁸ is a substituent other than a hydrogen atom (ie, an alkyl group having 1 to 20 carbon atoms or a fluoro group having 1 to 20 carbon atoms) roalkyl group).

(Ester group-containing acid dianhydride)

Content of the acid dianhydride represented by the said General formula (1) in 100 mol% of total amount of an acid dianhydride component is 40-85 mol%, 40-80 mol% is preferable, 40-75 mol% is more preferable, 45-70 mol% % or 50 to 65 mol% may be sufficient.

When content of the acid dianhydride represented by General formula (1) is in the said range, while being able to suppress remarkable thickening, gelatinization, etc. at the time of the polymerization reaction of polyamic acid or imidation reaction in a solution, polyimide resin solubility in low-boiling solvents of Moreover, when content of the acid dianhydride represented by General formula (1) exists in the said range, there exists a tendency for the mechanical strength of a polyimide film to improve.

The acid dianhydride represented by the general formula (1) is an ester of trimellitic anhydride and a biphenol having a substituent. Since the acid dianhydride represented by the general formula (1) has a biphenyl structure, the UV-resistant properties of the polyimide are high, and the decrease in transparency (increase in yellowness YI) accompanying UV irradiation tends to be suppressed.

Substituents R ¹ to R ⁸ in the general formula (1) are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, cyclobutyl group, n-pentyl group, isopentyl group, neopentyl group, cyclo A pentyl group, n-hexyl group, a cyclohexyl group, etc. are mentioned. Examples of the fluoroalkyl group include a monofluoromethyl group, a difluoromethyl group, a trifluoromethyl group, and a pentafluoroethyl group. Among the fluoroalkyl groups, perfluoroalkyl groups such as trifluoromethyl group and pentafluoroethyl group are preferable.

In the general formula (1), at least one of R ¹ to R ⁴ is a substituent other than a hydrogen atom, and at least one of R ⁵ to R ⁸ is a substituent other than a hydrogen atom. At least one of R ² and R ³ and at least one of R ⁶ and R ⁷ are preferably a substituent other than a hydrogen atom. If these are substituents other than hydrogen atoms, the bond between the two benzene rings of the biphenyl is twisted due to steric hindrance, and the planarity of the π-conjugation is lowered. .

In general formula (1), it is preferable that R< ² > and R< ⁶ > are a methyl group, and R< ³ > and R< ⁷ > are hydrogen atoms. Among them, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) represented by the following formula (2) wherein R ¹ , R ⁴ , R ⁵ and R ⁸ are methyl groups 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl (TAHMBP) is preferred.

(acid dianhydride containing cyclobutane structure)

Content of the acid dianhydride which has a cyclobutane structure in 100 mol% of whole quantity of an acid dianhydride component is 15-60 mol%, 15-50 mol% is preferable, and 15-40 mol% is more preferable. When the content of the acid dianhydride having a cyclobutane structure is 15 mol% or more, the mechanical strength of the polyimide film tends to improve, and when it is 60 mol% or less, the solubility of the polyimide resin in a low-boiling solvent or the like tends to improve. .

Specific examples of the acid dianhydride having a cyclobutane structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride. , 1,4-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride water, 1,3-dipropyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,4-dipropyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride; Cyclobutane-1,2:3,4-bis(tetramethylene)-1,2,3,4-tetracarboxylic dianhydride etc. are mentioned. Among them, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) is preferable.

(other acid dianhydrides)

You may use together acid dianhydride components other than the above in the range which does not impair the solubility with respect to low boiling point solvents, such as dichloromethane, and does not impair characteristics, such as transparency and mechanical strength. Examples of the acid dianhydride other than the above include 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2, 3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} and fluorine-containing aromatic acid dianhydrides such as -1,1,1,3,3,3-hexafluoropropane dianhydride. Examples of other acid dianhydrides include 3,3',4,4'-biphenyltetracarboxylic dianhydride, p-phenylenebistrimellitic dianhydride, 9,9-bis(3,4-dicarboxyphenyl) Fluorene dianhydride, ethylene tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid Acid dianhydride, 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic acid-3,4:3',4'-dianhydride, 3,3',4,4 '-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2, 2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis( 2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,3-bis[(3,4 -dicarboxy)benzoyl]benzene dianhydride, 1,4-bis[(3,4-dicarboxy)benzoyl]benzene dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy Cy]phenyl}propane dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride, bis{4-[4-(1,2-dicarboxy) ) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4'-bis [4- (1,2-dicarboxy) ) phenoxy] biphenyl dianhydride, 4,4'-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy Cy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy] Phenyl}sulfone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} sulfide dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenoxy cy]phenyl}-1,1, 1,3,3,3-propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7 -Anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, etc. are mentioned.

For example, as the acid dianhydride, in addition to the acid dianhydride represented by the general formula (1) and the acid dianhydride having a cyclobutane structure, 2,2-bis(3,4-dicarboxyphenyl)-1,1; By using 1,3,3,3-hexafluoropropane dianhydride (6FDA) or 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), it can be dissolved in a low boiling point solvent such as dichloromethane. There is a tendency for the mechanical strength of the polyimide film to increase while maintaining the solubility to the polyimide film. In particular, when 6FDA is used, the transparency of the polyimide film tends to improve. 5 mol% or more is preferable, as for content of 6FDA in 100 mol% of whole quantity of an acid dianhydride component, 10 mol% or more is more preferable, and 15 mol% or more may be sufficient. 5 mol% or more, 10 mol% or more, or 15 mol% or more may be sufficient as content of BPDA in 100 mol% of whole quantity of an acid dianhydride component.

In 100 mol% of the total amount of the acid dianhydride component, 40 mol% or less is preferable for content of acid dianhydrides other than the acid dianhydride represented by General formula (1) and the acid dianhydride which has a cyclobutane structure. 25 mol% or less is preferable in content of 6FDA in 100 mol% of whole quantity of an acid dianhydride component, and, as for content of BPDA, 25 mol% or less is preferable.

<Diamine>

(fluoroalkyl substituted benzidine)

The polyimide of the present invention contains a fluoroalkyl-substituted benzidine as a diamine component. Content of fluoroalkyl-substituted benzidine is 40-100 mol% in total 100 mol% of a diamine component, 60 mol% or more is preferable, and 70 mol% or more is more preferable. When content of a fluoroalkyl-substituted benzidine is 40 mol% or more, while coloring of a polyimide film is suppressed, there exists a tendency for pencil hardness and elasticity modulus to become high.

Examples of the fluoroalkyl substituted benzidine include 2,2'-dimethylbenzidine, 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(tri Fluoromethyl)benzidine, 2,3,6-tris(trifluoromethyl)benzidine, 2,3,5,6-tetrakis(trifluoromethyl)benzidine, 2,2'-bis(trifluoromethyl) )benzidine, 3,3'-bis(trifluoromethyl)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, etc. are mentioned.

Among them, fluoroalkyl-substituted benzidine having a fluoroalkyl group at the 2-position of biphenyl is preferable, and 2,2'-bis(trifluoromethyl)benzidine (hereinafter referred to as "TFMB") is particularly preferable. By having a fluoroalkyl group at the 2-position and the 2'-position of the biphenyl, in addition to the decrease in the π electron density due to the electron withdrawing property of the fluoroalkyl group, the steric hindrance of the fluoroalkyl group results in a difference between the two benzene rings of the biphenyl. Since the bond is twisted and the planarity of the ?-conjugated is lowered, the absorption edge wavelength is shifted to a shorter wavelength, and the coloration of the polyimide can be reduced.

(other diamines)

You may use together diamines other than the above in the range which does not impair the solubility with respect to low boiling point solvents, such as dichloromethane, and does not impair characteristics, such as transparency and mechanical strength. Examples of diamines other than fluoroalkyl-substituted benzidine include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether , 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3, 3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 9,9-bis(4-aminophenyl)fluorene, 3,3'- Diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4 '-Diaminodiphenylmethane, 2,2-di(3-aminophenyl)propane, 2,2-di(4-aminophenyl)propane, 2-(3-aminophenyl)-2-(4-aminophenyl) ) Propane, 1,1-di(3-aminophenyl)-1-phenylethane, 1,1-di(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1-(4 -Aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy) Benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene, 1,3-bis(4-aminobenzoyl)benzene, 1,4-bis(3- Aminobenzoyl)benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α -Dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 2,6-bis( 3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy) C)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide , bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4 -(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether Le, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4-(3) -Aminophenoxy)benzoyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,4 -bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-( 4-Aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-( 4-Aminophenoxy)-α,α-dimethylbenzyl]benzene, 4,4'-bis[4-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4- Amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4′-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, 4,4′-bis[ 4-(4-aminophenoxy)phenoxy]diphenylsulfone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxy Cybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3 ,3,3',3'-tetramethyl-1,1'-spirobindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1, 1'-spirobindane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl) Polydimethylsiloxane, α,ω-bis(3-aminobutyl)polydimethylsiloxane, bis(aminomethyl)ether, bis(2-aminoethyl)ether, bis(3-aminopropyl)ether, bis(2-aminomethyl) Toxy)ethyl]ether, bis[2-(2-aminoethoxy)ethyl]ether, bis[2-(3-aminopropoxy)ethyl]ether, 1,2-bis(aminomethoxy)ethane, 1, 2-bis(2-aminoethoxy)ethane, 1,2-bis[2-(aminomethoxy)ethoxy]ethane, 1,2-bis[2-(2-aminoethoxy)ethoxy]ethane; Ethylene glycol bis(3-aminopropyl) ether, diethylene glycol bis(3-aminopropyl) ether, triethylene glycol bis(3-aminopropyl) Phil) ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8 -Diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1 ,3-diaminocyclohexane, 1,4-diaminocyclohexane, trans-1,4-diaminocyclohexane, 1,2-di(2-aminoethyl)cyclohexane, 1,3-di(2- aminoethyl)cyclohexane, 1,4-di(2-aminoethyl)cyclohexane, bis(4-aminocyclohexyl)methane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 2, 5-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,4-diamino-2-fluorobenzene, 1,4-diamino-2,3-difluorobenzene, 1,4-dia mino-2,5-difluorobenzene, 1,4-diamino-2,6-difluorobenzene, 1,4-diamino-2,3,5-trifluorobenzene, 1,4-dia mino-2,3,5,6-tetrafluorobenzene, 1,4-diamino-2-(trifluoromethyl)benzene, 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 and 1,4-diamino-2,3,5,6-tetrakis(trifluoromethyl)benzene.

For example, by using diaminodiphenylsulfone in addition to fluoroalkyl-substituted benzidine as diamine, the solubility and transparency with respect to the solvent of polyimide resin may improve. Among the diaminodiphenylsulfones, 3,3'-diaminodiphenylsulfone (3,3'-DDS) and 4,4'-diaminodiphenylsulfone (4,4'-DDS) are preferable. You may use 3,3'-DDS and 4,4'-DDS together.

3 mol% or more is preferable, as for content of diaminodiphenyl sulfone with respect to 100 mol% of diamine whole quantity, 5 mol% or more is more preferable, 8 mol% or more, or 10 mol% or more may be sufficient. From a viewpoint of the mechanical strength of polyimide resin, 40 mol% or less is preferable and, as for content of diaminodiphenyl sulfone with respect to 100 mol% of diamine whole quantity, 30 mol% or less is more preferable.

<Composition of polyimide>

As described above, the polyimide of the present invention includes, as an acid dianhydride component, an acid dianhydride represented by the general formula (1) and an acid dianhydride having a cyclobutane structure, and includes a fluoroalkyl-substituted benzidine as a diamine. do. The acid dianhydride represented by the general formula (1) is preferably TAHMBP represented by the formula (2), the cyclobutane structure-containing acid dianhydride is preferably CBDA, and the fluoroalkyl-substituted benzidine is preferably TFMB. The polyimide may further contain 6FDA and/or BPDA as an acid dianhydride component, and may further contain 3,3'-DDS and/or 4,4'-DDS as a diamine component.

As for the quantity of TAHMBP, 40-85 mol% is more preferable in 100 mol% of whole quantity of an acid dianhydride component, and, as for the quantity of CBDA, 15-60 mol% is preferable. Moreover, it is preferable to contain 25 mol% or less of 6FDA and/or BPDA, respectively as an acid dianhydride component from a viewpoint of the solubility improvement of a polyimide resin, or a transparency improvement of a film.

In 100 mol% of diamine component whole quantity, 40-100 mol% is preferable and, as for the quantity of TFMB, 70-95 mol% is more preferable. Moreover, it is preferable to contain 5-30 mol% of 3,3'-DDS or 4,4'-DDS as a diamine component.

Since the polyimide having the above composition has high solubility in low boiling point solvents such as dichloromethane, the amount of residual solvent in the polyimide film can be easily reduced, and a polyimide film having high transmittance, low yellowness, and high mechanical strength is prepared. can be produced

[Method for producing polyimide resin]

Although the manufacturing method of a polyimide resin is not specifically limited, The method of making diamine and acid dianhydride react in a solvent to prepare the polyamic acid which is a polyimide precursor, and the method of imidation by dehydration cyclization of a polyamic acid is preferable. For example, a polyimide solution is obtained by adding an imidation catalyst and a dehydrating agent to a polyamic acid solution, and dehydrating and ring-closing a polyamic acid. A polyimide resin is obtained by mixing a polyimide solution and the poor solvent of a polyimide, depositing polyimide resin, and carrying out solid-liquid separation.

<Preparation of polyamic acid>

A polyamic acid solution is obtained by making an acid dianhydride and diamine react in a solvent. For polymerization of polyamic acid, an organic solvent capable of dissolving diamine and acid dianhydride as raw materials and polyamic acid as a polymerization product can be used without particular limitation. Specific examples of the organic solvent include urea solvents such as methylurea and N,N-dimethylethylurea; sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone and tetramethyl sulfone; Amides such as N,N-dimethylacetamide, N,N-dimethylformamide, N,N'-diethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, and hexamethylphosphoric acid triamide system solvent; halogenated alkyl solvents such as chloroform and dichloromethane; and ether solvents such as aromatic hydrocarbon solvents such as benzene and toluene, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These solvents may be used independently and may be used combining 2 or more types suitably. Among these, N,N-dimethylacetamide, N,N-dimethylformamide, or N-methylpyrrolidone is preferably used from the viewpoint of excellent polymerization reactivity and solubility of polyamic acid.

Polyamic acid polymerization proceeds by dissolving diamine and acid dianhydride in an organic solvent. The solid content concentration of the polyamic acid solution (the concentration of diamine and acid dianhydride in the reaction solution) is usually about 5 to 40% by weight, and preferably 10 to 30% by weight. The acid dianhydride and diamine are preferably used in equimolar amounts (95:105 to 105:95). When either component becomes excessive, the molecular weight of a polyamic acid and a polyimide may not become large enough, but the mechanical strength of a polyimide film may fall.

Although reaction temperature is not specifically limited, 0 degreeC or more and 80 degrees C or less are preferable, and 20 degreeC or more and 45 degrees C or less are more preferable. By setting it as 0 degreeC or more, the fall of the reaction rate can be suppressed and a polymerization reaction can be performed in a comparatively short time. Moreover, by setting it as 80 degrees C or less, the fall of the polymerization degree by ring-opening of an acid dianhydride component, etc. can be suppressed.

The order of addition of the diamine and acid dianhydride to the organic solvent (reaction system) in the polymerization of polyamic acid is not specifically limited. The arrangement of the monomer components (acid dianhydride-derived structure and diamine-derived structure) in the polyamic acid and polyimide may be random or may be a block.

A random polyamic acid is obtained by dissolving either the whole amount of the diamine or the total amount of the acid dianhydride in an organic solvent or dispersing it in a slurry form, and then adding the other one. For example, what is necessary is just to melt|dissolve or disperse|distribute diamine in an organic solvent in the form of a slurry, to set it as a diamine solution, and just to add an acid dianhydride to a diamine solution. You may add diamine to the solution which melt|dissolved the acid dianhydride in the organic polar solvent. A plurality of types of acid dianhydrides and diamines may be added at once, or may be added in portions in multiple times. The diamine and acid dianhydride may be added in a solid state, or may be added in a state dissolved or dispersed in an organic solvent in the form of a slurry.

Various physical properties of the polyimide obtained can also be controlled by adjusting the order of addition of the monomer. For example, (A) of a plurality of types of acid dianhydrides and diamines, by first reacting a specific acid dianhydride with a diamine, a segment (oligomer) having a structural unit (repeating unit) bonded with a specific acid dianhydride and diamine is formed do. After adjusting the oligomer (B) by adding the remainder of diamine and acid dianhydride to further advance the reaction (post polymerization), polyamic acid having a block structure in its molecule is obtained. By imidating this polyamic acid, the polyimide which contains in the molecular structure the block in which the structural unit which the specific diamine and the specific acid dianhydride couple|bonded is continuous is obtained. When polyimide has a block structure, there exists a tendency for the mechanical strength and heat resistance of a polyimide film to improve.

In the said process (A), the oligomer of an acid anhydride terminal or an amine terminal is formed by making either an acid dianhydride and a diamine in an excess amount and making it react. The amount of the acid dianhydride and diamine to be charged in the preparation of the oligomer is preferably 70 to 95 mol%, more preferably 75 to 90 mol%, based on the total amount of the input (the sum of the amounts of (A) and (B)).

Preparation of the oligomer WHEREIN: When the input amount of diamine is made larger than the input amount of acid dianhydride, an amine-terminal oligomer is produced|generated. In the case of preparing an amine-terminal oligomer, 1.01 to 1.25 times are preferable, 1.03 to 1.2 times are more preferable, 1.05 to 1.18 times are still more preferable in molar ratio with respect to the input amount of acid dianhydride. As the ratio of both is closer to 1, the molecular weight of the oligomer tends to increase.

In the preparation of the oligomer, a fluoroalkyl-substituted benzidine such as TFMB is contained as a diamine, and an acid dianhydride represented by the general formula (1) such as TAHMBP as an acid dianhydride and a cyclobutane structure-containing acid dianhydride such as CBDA It is preferable to include In particular, preference is given to using only fluoroalkyl-substituted benzidines as diamines. By adjusting the composition of the oligomer, that is, the structure of the block, the mechanical strength of the polyimide film tends to be improved.

In step (B), the balance of diamine and acid dianhydride is added so that the total amount of diamine and acid dianhydride is equimolar (95:105 to 105:95), whereby the oligomer prepared in step (A) is The terminal reacts with the monomer added in the step (B) to obtain a polyamic acid having an alternating block structure. By imidating this polyamic acid, the polyimide which contains in the molecular structure the block in which the structural unit which the specific diamine and the specific acid dianhydride couple|bonded is continuous is obtained.

In a process (B), the acid dianhydride and diamine of the remainder may be added simultaneously, and may be added sequentially. You may add the oligomer which made the remainder acid dianhydride and diamine react previously to the solution of the oligomer prepared by (A).

<Imidization>

Polyimide is obtained by dehydration cyclization of polyamic acid. For imidation in solution, a chemical imidization method in which a dehydrating agent, an imidization catalyst, or the like is added to a polyamic acid solution is suitable. In order to accelerate advancing of imidation, you may heat the polyamic-acid solution.

A tertiary amine is used as the imidation catalyst. As the tertiary amine, a heterocyclic tertiary amine is preferable. Specific examples of the heterocyclic tertiary amine include pyridine, picoline, quinoline and isoquinoline. As the dehydrating agent, carboxylic acid anhydride is used, and specific examples thereof include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like. The amount of the imidization catalyst added is preferably 0.5 to 5.0 molar equivalents, more preferably 0.7 to 2.5 molar equivalents, and still more preferably 0.8 to 2.0 molar equivalents with respect to the amide group of the polyamic acid. The amount of the dehydrating agent to be added is preferably 0.5 to 10.0-fold molar equivalent, more preferably 0.7 to 5.0-fold molar equivalent, and still more preferably 0.8 to 3.0-fold molar equivalent with respect to the amide group of the polyamic acid.

<Precipitation of polyimide resin>

Although the polyimide solution obtained by imidation of a polyamic acid can also be used as dope for film forming as it is, it is preferable to make polyimide resin precipitate as a solid thing once. By precipitating the polyimide resin as a solid substance, impurities generated during polymerization of polyamic acid, residual monomer components, dehydrating agent, imidization catalyst, and the like can be washed and removed. Therefore, a polyimide film excellent in transparency and mechanical properties is obtained.

By mixing a polyimide solution and a poor solvent, polyimide resin is precipitated. A poor solvent is a poor solvent of polyimide resin, It is preferable to be miscible with the solvent in which the polyimide resin is melt|dissolving, Water, alcohol, etc. are mentioned. 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, and t-butyl alcohol. . Since ring-opening of polyimide is less likely to occur, alcohols such as isopropyl alcohol, 2-butyl alcohol, 2-pentyl alcohol, phenol, cyclopentyl alcohol, cyclohexyl alcohol and t-butyl alcohol are preferable, and isopropyl alcohol This is particularly preferred.

[Polyimide Film]

A polyimide film can be manufactured by apply|coating the polyimide solution (dope for film forming) which melt|dissolved the polyimide resin in the organic solvent on a base material, and drying-removing the solvent.

As an organic solvent in which polyimide resin is dissolved, if the said polyimide resin is a thing soluble in dissolution, it will not specifically limit. Since the solvent can be easily removed by drying and the amount of residual solvent of the polyimide film can be reduced, low-boiling solvents such as dichloromethane, methyl acetate, tetrahydrofuran, acetone, and 1,3-dioxolane are preferable, and among them, Dichloromethane is particularly preferred. As described above, by setting the composition ratio of the acid dianhydride component and the diamine component to a predetermined range, a polyimide exhibiting high solubility in a low boiling point solvent such as dichloromethane can be obtained.

What is necessary is just to set the solid content concentration of a polyimide solution suitably according to the molecular weight of a polyimide, the thickness of a film, film forming environment, etc. 5 to 30 weight% is preferable and, as for solid content concentration, 8 to 20 weight% is more preferable.

The polyimide solution may contain resin components and additives other than a polyimide. As an additive, a ultraviolet absorber, a crosslinking agent, dye, surfactant, a leveling agent, a plasticizer, microparticles|fine-particles, etc. are mentioned. 60 weight part or more is preferable, as for content of polyimide resin with respect to 100 weight part of solid content of a polyimide solution (film forming dope), 70 weight part or more is more preferable, 80 weight part or more is still more preferable.

As a method of apply|coating a polyimide solution to a base material, a well-known method can be used, For example, it can apply|coat with a bar coater or a comma coater. As a base material to which a polyimide solution is apply|coated, a glass substrate, metal substrates, such as SUS, a metal drum, a metal belt, a plastic film, etc. can be used. From a viewpoint of productivity improvement, it is preferable to use endless supports, such as a metal drum, a metal belt, or a long plastic film, etc. as a support body, and to manufacture a film by roll-to-roll. When using a plastic film as a support body, what is necessary is just to select suitably the material which does not melt|dissolve in the solvent of film forming dope, As a plastic material, polyethylene terephthalate, polycarbonate, polyacrylate, polyethylene naphthalate, etc. are used.

It is preferable to heat when drying a solvent. Although heating temperature is not specifically limited, From a viewpoint of suppressing coloring, 200 degrees C or less is preferable, and 180 degrees C or less is more preferable. In drying the solvent, the heating temperature may be raised stepwise. You may dry a solvent under reduced pressure. Since the said polyimide resin is soluble in low-boiling-point solvents, such as dichloromethane, it can reduce the residual solvent easily also in heating at 200 degrees C or less.

1.5 % or less is preferable and, as for the amount of residual solvent (mass of the solvent contained in a film with respect to the mass of a film) of a polyimide film, 1.0 % or less is more preferable. There exists a tendency for the mechanical strength of a polyimide film to improve that the amount of residual solvent is this range.

The thickness of a polyimide film is not specifically limited, What is necessary is just to set suitably according to a use. The thickness of a polyimide film is about 5-100 micrometers, for example. In applications requiring impact resistance, such as a cover window material for a display, the thickness of the polyimide film is preferably 30 µm or more, more preferably 35 µm or more, and still more preferably 40 µm or more. The polyimide film of the present invention has excellent transparency even when the film thickness is as thick as 40 µm or more. From a viewpoint of maintaining the outstanding transparency, 90 micrometers or less are preferable and, as for the thickness of a polyimide film, 85 micrometers or less are more preferable.

[Characteristics of polyimide film]

3.0 or less are preferable and, as for yellowness (YI) of a polyimide film, 2.5 or less are more preferable. When the degree of yellowness is 3.0 or less, the film is not colored yellow and can be suitably used as a film for displays or the like.

80 % or more is preferable and, as for the total light transmittance of a polyimide film, 85 % or more is more preferable. Moreover, 35 % or more is preferable and, as for the light transmittance in wavelength 400nm of a polyimide film, 40 % or more is more preferable. 4.9 GPa or more is preferable, as for the tensile modulus of elasticity of a polyimide film, 5.0 GPa or more are more preferable, and 5.2 GPa or more are still more preferable.

From the viewpoint of preventing the occurrence of scratches on the film due to the contact with the roll during roll-to-roll conveyance or the contact between the films during winding, the pencil hardness of the polyimide film is preferably HB or more, and more preferably F or more. . When a polyimide film is used for a cover window of a display, etc., since abrasion resistance with respect to contact from the outside is calculated|required, it is preferable that the pencil hardness of a polyimide film is H or more.

[Use of polyimide film]

The polyimide film of the present invention has a small degree of yellowness and high transparency, and is suitably used as a display material. In particular, a polyimide film having high mechanical strength can be applied to a surface member such as a cover window of a display. In the case of practical use, the polyimide film of this invention may provide an antistatic layer, an easily bonding layer, a hard-coat layer, an antireflection layer, etc. on the surface.

Example

Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples. In addition, the present invention is not limited to the following examples.

[Preparation of polyamic acid solution]

<Polymerization of random bodies: Examples 3, 10 to 12, Comparative Examples 1, 7, 8>

N,N-dimethylformamide as a solvent was put into a separable flask, and while stirring under a nitrogen atmosphere, diamine and acid dianhydride in the molar ratios shown in Composition A of Table 1 were added, and stirred for 5 hours under a nitrogen atmosphere to achieve solid content concentration An 18% polyamic acid solution was obtained.

<Polymerization of block: Examples 1, 2, 4 to 9, Comparative Examples 2 to 6>

N,N-dimethylformamide as a solvent was added to a separable flask, and while stirring under a nitrogen atmosphere, diamine and acid dianhydride in the molar ratios shown in composition A in Table 1 were added, and stirred under a nitrogen atmosphere for 10 hours to obtain an oligomer synthesized. Thereafter, diamine and acid dianhydride were added in the molar ratios shown in composition B in Table 1, followed by stirring under nitrogen atmosphere for a period of time to perform post-polymerization to obtain a polyamic acid solution having a solid content concentration of 18%.

The abbreviations of the raw material monomers shown in Table 1 are as follows.

TMHQ: p-phenylenebistrimellitic dianhydride

TAHMBP: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)2,2',3,3',5,5'-hexamethylbiphenyl-4,4 '-Dail

6FDA: 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

TFMB: 2,2'-bis(trifluoromethyl)benzidine

3,3'-DDS: 3,3'-diaminodiphenylsulfone

4,4'-DDS: 4,4'-diaminodiphenylsulfone

[Imidation, isolation of polyimide resin, and preparation of polyimide solution]

To 100 g of the polyamic acid solution, 5.5 g of pyridine as an imidation catalyst was added and completely dispersed, and then 8 g of acetic anhydride was added thereto, followed by stirring at 90°C for 3 hours to perform imidization. With respect to that in which the solution did not gel, 100 g of 2-propyl alcohol (hereinafter referred to as "IPA") was dripped at a rate of 2-3 drops/sec while stirring the solution cooled to room temperature to precipitate polyimide. Furthermore, 150 g of IPA was added, and after stirring for about 30 minutes, suction filtration was performed using the Kiriyama funnel. The obtained solid was washed with 100 g of IPA. After repeating a washing|cleaning operation 6 times, it was made to dry in the vacuum oven set to 120 degreeC for 8 hours, and the polyimide resin was obtained. Moreover, in Comparative Examples 1-5, since the solution viscosity rapidly increased and gelatinized in the middle of imidation, a polyimide solution was not obtained. Therefore, in these comparative examples, subsequent operation and evaluation were not implemented.

DCM solubility of the polyimide resin was evaluated by adding 9 g of dichloromethane (DCM) to 1 g of the polyimide resin obtained above, stirring at room temperature for 12 hours, and then visually confirming the presence or absence of a dissolved substance. What was visually clear solution was made DCM "soluble", and what was confirmed as a solid content which melted and remained was made DCM "insoluble". In addition, about the thing gelled at the time of imidation, Table 1 describes as "gelatinization".

[Production of polyimide film]

Polyimide resin was melt|dissolved in dichloromethane (henceforth "DCM"), and the polyimide solution of 10 weight% of solid content concentration was obtained. The polyimide solution is applied to an alkali-free glass plate using a bar coater, and the solvent is removed by heating at 40 ° C. for 60 minutes, 80 ° C. for 30 minutes, 150 ° C. for 30 minutes, and at 170 ° C. for 30 minutes, in an atmospheric atmosphere. The polyimide film of the thickness shown in Table 1 was obtained. In addition, since the polyimide resin of Comparative Example 8 did not melt|dissolve in DCM, the polyimide solution which melt|dissolved the polyimide resin in methyl ethyl ketone (MEK) was used and the film was produced.

[Evaluation of polyimide film]

(Tensile Modulus)

"AUTOGRAPH AGS-X" manufactured by Shimadzu Corporation was used for the measurement under the following conditions. sample measurement range; width 10 mm, gripping tool distance 100 mm, tensile speed; 20.0 mm/min, measurement temperature; 23°C. As the sample, one in which humidity was controlled by leaving still at 23°C/55%RH for 1 day was used.

(yellow degree)

The yellowness (YI) was measured with the spectrophotometer "SC-P" manufactured by Suga Industrial Co., Ltd. using a sample having a square size of 3 cm on one side.

(pencil hardness)

According to JISK-5600-5-4 "pencil scratch test", the pencil hardness of the film was measured.

(transmittance at 400 nm)

The light transmittance in 300-800 nm of the film was measured using the ultraviolet-visible spectrophotometer "V-560" by the Nippon Bunko Corporation, and the light transmittance in the wavelength of 400 nm was read.

(total light transmittance)

It measured by the method of JISK7361-1 using the haze meter "HZ-V3" manufactured by Suga Industrial Co., Ltd.

(Residual solvent amount)

Using about 8.9 g of 1,3-dioxolane as a solvent, about 0.1 g of a polyimide film and about 1 g of diethylene glycol butylmethyl ether (DEGBME) as an internal standard were dissolved to prepare a measurement sample. This solution was measured using a gas chromatograph apparatus (GC, manufactured by Shimadzu Corporation), and the amount of residual solvent (DCM or MEK) contained in the polyimide film was determined from the GC peak area and the preparation concentration.

Composition (molar ratio of acid dianhydride and diamine input amount in polymerization of polyamic acid) of the polyimide resins of Examples and Comparative Examples, solubility in DCM, solvent used for film formation, and evaluation results of polyimide films is shown in Table 1.

As shown in Table 1, in Examples 1 to 12, the polyimide showed DCM solubility, and the polyimide film showed a tensile modulus of 5 GPa or more, indicating that excellent mechanical strength and transparency were compatible.

In Comparative Example 1 in which the amount of CBDA with respect to the total amount of acid dianhydride was 10 mol%, the solvent solubility of the polyimide was low, and the polyimide resin could not be isolated because the solution gelled during imidization. In Comparative Example 2 without CBDA, Comparative Example 3 in which the amount of TAHMBP was 35 mol%, and Comparative Example 4 in which the amount of TAHMBP was 25 mol%, gelation occurred during imidization as in Comparative Example 1.

As the acid dianhydride, in Comparative Example 5 using TMHQ, which is a trimellitic acid dianhydride ester, gelation occurred during imidization. From the comparison between Example 6 and Comparative Example 5, it can be seen that the polyimide having a structure derived from TAHMBP, which is an acid dianhydride having a substituent on the benzene ring of biphenyl, has excellent solvent solubility.

In Comparative Example 8 using a combination of CBDA and 6FDA as the acid dianhydride, gelation did not occur upon imidization, but the isolated polyimide did not show DCM solubility. Although the polyimide film of Comparative Example 8 formed into a film using MEK as a solvent exhibited excellent transparency, the tensile modulus of elasticity was 4.1 GPa, and the mechanical strength was inferior compared with the Example. Moreover, in Comparative Example 8, the amount of residual solvent in MEK was 2.8%, and the amount of residual solvent was large compared to the other examples in which DCM was used. In Comparative Example 8, since DCM, which is a low boiling point solvent, cannot be used, it is difficult to obtain a polyimide film with a small amount of residual solvent. this is difficult

In Comparative Examples 6 and 7, CBDA was not used as the acid dianhydride, but since the introduction ratio of TAHMBP and 6FDA was increased, a polyimide resin soluble in DCM was obtained. However, the polyimide films of Comparative Examples 6 and 7 had a tensile modulus of less than 5 GPa and had insufficient mechanical strength.

From the above results, fluoroalkyl-substituted benzidine as a diamine component, an ester of trimellitic acid dianhydride with a biphenol having a substituent on the benzene ring as an acid dianhydride, and an acid dianhydride having a cyclobutane structure in a predetermined ratio Since polyimide is soluble in low boiling point solvents, such as DCM, it can be seen that a film with a small amount of residual solvent can be easily produced, and mechanical properties and transparency of a polyimide film are compatible.

From the comparison between Examples 1 and 2 and Example 3 and the comparison between Examples 8 and 9 and Example 10, it can be seen that the polyimide having a block structure exhibits a higher modulus of elasticity than the polyimide having a random structure of the same composition. can In particular, in Examples 1 and 8 in which a block containing only TFMB as a diamine component was formed, a tendency for the tensile modulus of polyimide film to improve was observed.

Claims (16)

It is a polyimide resin having an acid dianhydride-derived structure and a diamine-derived structure,
As the diamine, 40 to 100 mol% or less of fluoroalkyl-substituted benzidine is included with respect to 100 mol% of the total amount of the diamine,
As the acid dianhydride, 40 to 85 mol% of the acid dianhydride represented by the general formula (1) and 15 to 60 mol% or less of the acid dianhydride having a cyclobutane structure with respect to 100 mol% of the total amount of the acid dianhydride,
Polyimide resin:

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a perfluoroalkyl group having 1 to 20 carbon atoms, and among R ¹ to R ⁴ At least one and at least one of R ⁵ to R ⁸ is an alkyl group having 1 to 20 carbon atoms or a fluoroalkyl group having 1 to 20 carbon atoms. The polyimide resin according to claim 1, wherein the acid dianhydride represented by the general formula (1) is a compound represented by the formula (2).

The polyimide resin according to claim 1 or 2, wherein the acid dianhydride having a cyclobutane structure is 1,2,3,4-cyclobutanetetracarboxylic dianhydride. The polyimide resin according to any one of claims 1 to 3, wherein the fluoroalkyl substituted benzidine is 2,2'-bis(trifluoromethyl)benzidine. 5. The acid dianhydride according to any one of claims 1 to 4, further comprising 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexa A polyimide resin comprising fluoropropane dianhydride. The polyimide resin according to any one of claims 1 to 5, further comprising 3,3'-4,4'-biphenyltetracarboxylic dianhydride as the acid dianhydride. The polyimide resin according to any one of claims 1 to 6, further comprising 5 to 40 mol% of diaminodiphenylsulfone as the diamine. A method for producing the polyimide resin according to any one of claims 1 to 7, comprising:
A polyamic acid solution is prepared by reacting the diamine and the acid dianhydride in a solvent,
A method for producing a polyimide resin, wherein the polyamic acid is imidized by adding a dehydrating agent and an imidization catalyst to the polyamic acid solution. The method for producing a polyimide resin according to claim 8, further comprising mixing a polyimide solution in which the polyimide is dissolved in an organic solvent and a poor solvent of the polyimide to precipitate the polyimide resin. 10. The method according to claim 8 or 9, in the preparation of the polyamic acid solution,
(A) by reacting either one of an acid dianhydride and diamine in an excess amount to adjust an acid anhydride terminal or an amine terminal oligomer;
(B) performing post-polymerization by adding the remainder of diamine and acid dianhydride so that the total amount of diamine and the total amount of acid dianhydride are equimolar;
A method for producing a polyimide resin. 10. The method according to claim 8 or 9, in the preparation of the polyamic acid solution,
After dissolving or dispersing one of the total amount of the diamine and the total amount of the acid dianhydride in an organic solvent, the other is added,
A method for producing a polyimide resin. The polyimide film containing the polyimide resin in any one of Claims 1-7. The polyimide film according to claim 12, wherein the tensile modulus is 5.0 GPa or more. The polyimide film according to claim 12 or 13, wherein the pencil hardness is H or more. 15. The polyimide film according to any one of claims 12 to 14, wherein the degree of yellowness is 3.0 or less. A method for producing a polyimide film, wherein a polyimide solution in which the polyimide resin according to any one of claims 1 to 7 is dissolved in a solvent containing dichloromethane is applied to a substrate, and the solvent is removed.