TW202106764A - Polyimide resin and method for producing same, and polyimide film and method for producing same - Google Patents

Abstract

This polyimide resin has an acid dianhydride-derived structure and a diamine-derived structure, contains 40-100 mol% of a fluoroalkyl-substituted benzidine, as a diamine, with respect to a total of 100 mol% of the diamine, and contains, as an acid dianhydride, 40-85 mol% of an acid dianhydride represented by general formula (1) and 15-60 mol% of an acid dianhydride having a cyclobutane structure, with respect to a total of 100 mol% of the acid dianhydride. In general formula (1), R1-R8 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a perfluoro alkyl group having 1 to 20 carbon atoms, and at least one among R1-R4 and at least one among R5-R8 are an alkyl group having 1 to 20 carbon atoms, or a perfluoro alkyl group having 1 to 20 carbon atoms.

Description

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

The invention relates to a polyimide resin and a manufacturing method thereof, a polyimide solution, a polyimide film and a manufacturing method thereof.

In order to achieve lightweight or flexible display devices such as smart phones, research and application of polyimide film as a replacement material for glass previously used as substrates or surface protection materials. General polyimide is colored yellow or brown, and does not show solubility in organic solvents, but by introducing an alicyclic structure or fluoroalkyl group, a low-color polyimide can be obtained (for example, Patent Document 1) . [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2006-282884

[The problem to be solved by the invention]

The polyimide film obtained from the polyimide resin of Patent Document 1 has insufficient mechanical strength for a cover window or the like arranged on the outer surface of a device. The object of the present invention is to provide a polyimide resin and polyimide film which are dissolved in a low-boiling solvent such as methylene chloride and are excellent in transparency and mechanical strength. [Technical means to solve the problem]

The polyimide resin of one embodiment of the present invention has a structure derived from an acid dianhydride and a structure derived from a diamine. As the acid dianhydride, it includes the acid dianhydride represented by the general formula (1) and the one having a cyclobutane structure Acid dianhydride, as a diamine, includes benzidine substituted with a fluoroalkyl group.

[化1]

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, or a perfluoroalkyl group with 1 to 20 carbon atoms, and one of R ¹ to R ⁴ One or more and one or more of R ⁵ to R ⁸ are alkyl groups having 1 to 20 carbon atoms or fluoroalkyl groups having 1 to 20 carbon atoms.

The amount of the acid dianhydride represented by the general formula (1) is 100 mol% of the total amount of the acid dianhydride, preferably 40 to 85 mol%. The amount of the acid dianhydride having a cyclobutane structure is 100 mol% relative to the total amount of the acid dianhydride, preferably 15-60 mol%. The amount of benzidine substituted by the fluoroalkyl group is 100 mol% of the total amount of diamine, preferably 40-100 mol%.

As a specific example of the acid dianhydride represented by general formula (1), the compound represented by formula (2) can be mentioned.

[化2]

As a specific example of the acid dianhydride containing a cyclobutane structure, 1,2,3,4-cyclobutane tetracarboxylic dianhydride can be mentioned. As a specific example of benzidine substituted with a fluoroalkyl group, 2,2'-bis(trifluoromethyl)benzidine can be cited.

Polyimine may also contain acid dianhydride components or diamine components other than the above. Examples of acid dianhydrides other than the above include 3,3',4,4'-biphenyltetracarboxylic dianhydride and 2,2-bis(3,4-dicarboxyphenyl)-1,1 ,1,3,3,3-hexafluoropropane dianhydride. As examples of diamines other than the above, diaminodiphenyl sulfonium can be cited.

The polyimide resin is dissolved in a solvent to prepare a polyimide solution, the polyimide solution is coated on the substrate, and the solvent is removed, thereby obtaining a polyimide film. As a solvent for dissolving polyimide, a low boiling point solvent such as methylene chloride is preferred.

The thickness of the polyimide film can be 40 μm or more. The yellowness of the polyimide film can be 3.0 or less, the tensile elastic modulus can be 5.0 GPa or more, and the pencil hardness can be H or more. [Effects of Invention]

The polyimide resin of the present invention is soluble in low-boiling solvents such as dichloromethane, and reduces residual solvents without heating at high temperatures, so a polyimide film with higher transparency can be obtained. The polyimide resin of the present invention is soluble in low-boiling solvents such as dichloromethane, and reduces residual solvents without heating at high temperatures, so a polyimide film with higher transparency can be obtained. The polyimide film of the present invention has high mechanical strength and high transparency even when the film thickness is large, so it can be used as a substrate material for a display or a cover window material.

[Polyimide resin] Polyimines are generally obtained by dehydrating and cyclizing polyimidic acid obtained by the reaction of tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid dianhydride") and diamine. That is, polyimide has a structure derived from acid dianhydride and a structure derived from diamine. The polyimide resin of the present invention contains ester group-containing acid dianhydride (bistrimellitic acid anhydride ester) and acid dianhydride having an alicyclic structure as the acid dianhydride component, and contains benzidine substituted by fluoroalkyl group as the two Amine component.

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

[化3]

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 (that is, an alkyl group with 1 to 20 carbon atoms or an alkyl group with 1 carbon atom). ～20 fluoroalkyl).

(Ester-containing dianhydride) In 100 mol% of the total amount of acid dianhydride components, the content of the acid dianhydride represented by the general formula (1) is 40 to 85 mol%, preferably 40 to 80 mol%, more preferably 40 to 75 mol% It can also be 45-70 mol% or 50-65 mol%. When the content of the acid dianhydride represented by the general formula (1) is within the above range, it can inhibit significant thickening or gelation during the polymerization reaction of polyamide acid or the imidization reaction in the solution Etc., and can ensure the solubility of polyimide resin to low boiling point solvents. Moreover, when the content of the acid dianhydride represented by the general formula (1) is within the above range, the mechanical strength of the polyimide film tends to be improved.

The acid dianhydride represented by the general formula (1) is an ester of trimellitic anhydride and a substituted biphenol. Since the acid dianhydride represented by the general formula (1) has a biphenyl structure, the UV resistance of polyimide is improved, and the decrease in transparency (increase in yellowness YI) accompanying ultraviolet irradiation tends to be suppressed.

^{The substituents R 1} to R ⁸ in the general formula (1) are each independently a hydrogen atom, an alkyl group having 1 to 20 carbons, or a fluoroalkyl group having 1 to 20 carbons. Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, cyclobutyl, n-pentyl, isopentyl, and neopentyl. Group, cyclopentyl, n-hexyl, cyclohexyl, etc. Examples of the fluoroalkyl group include monofluoromethyl, difluoromethyl, trifluoromethyl, and pentafluoroethyl. Among the fluoroalkyl groups, perfluoroalkyl groups such as trifluoromethyl and pentafluoroethyl are preferred.

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. It is preferable that ^{at least one of R 2} and R ³ and at least one of R ⁶ and R ⁷ is a substituent other than a hydrogen atom. If these are substituents other than the hydrogen atom, the bond between the two benzene rings of biphenyl is twisted by steric hindrance to reduce the flatness of π-conjugation, so there is a short wavelength shift in the absorption end wavelength. The tendency of polyimide to decrease its coloration.

In the general formula (1), it is preferable that R ² and R ⁶ are methyl groups, and R ³ and R ⁷ are hydrogen atoms. Among them, the bis(1,3-dioxy-1,3-dihydroisobenzofuran) represented by the following formula (2) in which ^{R 1} , R ⁴ , R ⁵ and R ^{8 are methyl groups are preferred} -5-carboxylic acid) 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diester (TAHMBP).

[化4]

(Acid dianhydride containing cyclobutane structure) In 100 mol% of the total amount of the acid dianhydride components, the content of the acid dianhydride having a cyclobutane structure is 15-60 mol%, preferably 15-50 mol%, more preferably 15-40 mol%. When the content of the acid dianhydride with the cyclobutane structure is 15 mol% or more, the mechanical strength of the polyimide film tends to be improved, and the content of the acid dianhydride with the cyclobutane structure is less than 60 mol% , There is a tendency for the solubility of polyimide resins to increase in low boiling point solvents.

Specific examples of acid dianhydrides having a cyclobutane structure include 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-ring Butane tetracarboxylic dianhydride, 1,4-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3 ,4-Cyclobutane tetracarboxylic dianhydride, 1,3-dipropyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,4-dipropyl-1,2,3 ,4-Cyclobutane tetracarboxylic dianhydride, cyclobutane-1,2:3,4-bis(tetramethylene)-1,2,3,4-tetracarboxylic dianhydride, etc. Among them, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) is preferred.

(Other acid dianhydrides) The acid dihydrate components other than the above can also be used in combination within the range that does not impair the solubility to low-boiling solvents such as methylene chloride and does not impair the properties such as transparency or mechanical strength. Examples of acid dianhydrides 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}-1,1,1,3,3,3-hexafluoropropane dianhydride and other fluorinated aromatic acid dianhydrides. Examples of other acid dianhydrides include 3,3',4,4'-biphenyltetracarboxylic dianhydride, p-phenylene bistrimellitic dianhydride, 9,9-bis(3,4-dicarboxyl (Phenyl) dianhydride, ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-ring Hexanetetracarboxylic dianhydride, 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic acid-3,4:3',4'-dianhydride, 3,3',4 ,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic 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) bismuth Anhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride Anhydride, 1,3-bis[(3,4-dicarboxy)benzoyl]phthalic anhydride, 1,4-bis[(3,4-dicarboxy)benzoyl]phthalic anhydride, 2, 2-bis{4-[4-(1,2-dicarboxy)phenoxy]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)benzene Oxy]phenyl)ketone dianhydride, 4,4'-bis[4-(1,2-dicarboxy)phenoxy]biphthalic anhydride, 4,4'-bis[3-(1,2- Dicarboxyl)phenoxy]biphenyl dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2- Dicarboxyl)phenoxy]phenyl)ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfuric anhydride, bis{4-[3-(1, 2-Dicarboxyl)phenoxy]phenyl}sulfuric dianhydride, bis{4-[4-(1,2-dicarboxyl)phenoxy]phenyl}sulfide dianhydride, bis{4-[3- (1,2-Dicarboxyl)phenoxy]phenyl)sulfide dianhydride, 2,2-bis{4-[3-(1,2-dicarboxyl)phenoxy]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 acid Dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, etc.

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, 1,1,3,3,3-hexafluoropropane dianhydride (6FDA) or 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) to keep the dichloromethane and other low The solubility of boiling point solvents and the tendency of the mechanical strength of polyimide membranes to increase. In particular, when 6FDA is used, the transparency of the polyimide film tends to increase. In 100 mol% of the total amount of acid dianhydride components, the content of 6FDA is preferably 5 mol% or more, more preferably 10 mol% or more, or 15 mol% or more. In 100 mol% of the total amount of acid dianhydride, the content of BPDA can be 5 mol% or more, 10 mol% or more, or 15 mol% or more.

In 100 mol% of the total amount of acid dianhydride components, the content of acid dianhydrides other than the acid dianhydride represented by the general formula (1) and the acid dianhydride having a cyclobutane structure is preferably 40 mol% or less. In 100 mol% of the total amount of acid dianhydride components, the content of 6FDA is preferably 25 mol% or less, and the content of BPDA is preferably 25 mol% or less.

＜Diamine＞ (Benzidine substituted with fluoroalkyl) The polyimide of the present invention contains benzidine substituted with a fluoroalkyl group as a diamine component. Among the total 100 mol% of the diamine components, the content of benzidine substituted with fluoroalkyl groups is 40-100 mol%, preferably 60 mol% or more, and more preferably 70 mol% or more. If the content of benzidine substituted with a fluoroalkyl group is more than 40 mol%, the coloration of the polyimide film is suppressed, and the pencil hardness or elastic modulus tends to increase.

Examples of benzidine substituted with a fluoroalkyl group 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'-Trifluoro Benzidine, 2,2',5-trifluorobenzidine, 2,2',6-trifluorobenzidine, 2,3',5-trifluorobenzidine, 2,3',6,-trifluorobenzidine Aniline, 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 (Methyl)benzidine, 2,3,5-tris(trifluoromethyl)benzidine, 2,3,6-tris(trifluoromethyl)benzidine, 2,3,5,6-tetra(trifluoromethyl)benzidine (Methyl)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 Aniline, 2,2',6-tris(trifluoromethyl)benzidine, 2,3',5-tris(trifluoromethyl)benzidine, 2,3',6,-tris(trifluoromethyl) ) Benzidine, 2,2',3,3'-Tetra(trifluoromethyl)benzidine, 2,2',5,5'-Tetra(trifluoromethyl)benzidine, 2,2',6 , 6'-Tetra(trifluoromethyl)benzidine, etc.

Among them, preferred is a fluoroalkyl substituted benzidine having a fluoroalkyl group at the 2-position of biphenyl, and particularly preferred is 2,2'-bis(trifluoromethyl)benzidine (hereinafter referred to as "TFMB") . Because biphenyl has a fluoroalkyl group at the 2 and 2'positions, in addition to the decrease in the π electron density caused by the electron withdrawing property of the fluoroalkyl group, the steric hindrance of the fluoroalkyl group makes the two biphenyl groups The bond between the benzene rings is twisted to reduce the planarity of the π conjugation, so the absorption end wavelength has a short wavelength shift, which can reduce the coloring of polyimide.

(Other diamines) Diamines other than the above can also be used in combination within the range that does not impair the solubility to low-boiling solvents such as dichloromethane, and does not impair the properties such as transparency or mechanical strength. Examples of diamines other than benzidine substituted with fluoroalkyl groups 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'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 9, 9-bis(4-aminophenyl) benzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone Ketone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl) )Propane, 2,2-bis(4-aminophenyl)propane, 2-(3-aminophenyl)-2-(4-aminophenyl)propane, 1,1-bis(3-amine Phenyl)-1-phenylethane, 1,1-bis(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1-(4-aminophenyl) Yl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-amine Phenyloxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzyl)benzene, 1,3-bis(4-amino) Benzoyl)benzene, 1,4-bis(3-aminobenzyl)benzene, 1,4-bis(4-aminobenzyl)benzene, 1,3-bis(3-amine -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) Biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy) Yl)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-( 4-aminophenoxy) phenyl] sulfide, bis[4-(3-aminophenoxy)phenyl] ether, bis[4-(4-aminophenoxy)phenyl] ether, 2 ,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis[4 -(3-Aminophenoxy)benzyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzyl]benzene, 1,4-bis[4-( 3-aminophenoxy)benzyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzyl]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)benzyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-α ,α-Dimethylbenzyl)phenoxy]diphenyl sulfide, 4,4'-bis[4-(4-aminophenoxy)phenoxy]diphenyl sulfide, 3,3'-diamine -4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-diphenyloxybenzophenone, 3,3'-diamino-4 -Phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3 ',3'-tetramethyl-1,1'-spirobiindene, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1, 1'-Spirobiindene, 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-aminomethoxy)ethyl]ether, bis[2-(2-aminoethoxy) Ethyl]ether, bis[2-(3-aminopropoxy)ethyl]ether, 1,2-bis(aminomethoxy)ethane, 1,2-bis(2-aminoethoxy) Yl)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) ether, ethylene diamine, 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 -Bis(2-aminoethyl)cyclohexane, 1,3-bis(2-aminoethyl)cyclohexane, 1,4-bis(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-diamino-2,5-difluorobenzene, 1,4-diamine 2,6-difluorobenzene, 1,4-diamino-2,3,5-trifluorobenzene, 1,4-diamino-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, 1,4-diamino-2,3,5,6-tetra(trifluoromethyl)benzene.

For example, as the diamine, in addition to benzidine substituted with a fluoroalkyl group, diaminodiphenyl sulfide is used, whereby the solubility or transparency of the polyimide resin to the solvent may be improved. Among the diaminodiphenyl sulfides, 3,3'-diaminodiphenyl sulfides (3,3'-DDS) and 4,4'-diaminodiphenyl sulfides (4,4' -DDS). 3,3'-DDS and 4,4'-DDS can also be used together.

The content of diaminodiphenyl sulfide relative to 100 mol% of the total amount of diamine is preferably 3 mol% or more, more preferably 5 mol% or more, and may also be 8 mol% or more or 10 mol% or more. From the viewpoint of the mechanical strength of the polyimide resin, the content of diaminodiphenyl sulfide relative to 100 mol% of the total amount of diamine is preferably 40 mol% or less, more preferably 30 mol% or less.

＜The composition of polyimide＞ As described above, the polyimide of the present invention includes the acid dianhydride represented by the general formula (1) and the acid dianhydride having a cyclobutane structure as the acid dianhydride component, and includes benzidine substituted with a fluoroalkyl group as the two amine. The acid dianhydride represented by the general formula (1) is preferably TAHMBP represented by the formula (2), and the acid dianhydride containing a cyclobutane structure is preferably CBDA, as the benzidine substituted by a fluoroalkyl group , Preferably TFMB. Polyimide may further include 6FDA and/or BPDA as the acid dianhydride component, and may further include 3,3'-DDS and/or 4,4'-DDS as the diamine component.

In 100 mol% of the total amount of acid dianhydride components, the amount of TAHMBP is more preferably 40 to 85 mol%, and the amount of CBDA is preferably 15 to 60 mol%. Furthermore, from the viewpoint of improving the solubility of the polyimide resin or the transparency of the film, it is preferable to each contain 25 mol% or less of 6FDA and/or BPDA as the acid dianhydride component.

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

The polyimide of the above composition has high solubility in low-boiling solvents such as dichloromethane, so it can easily reduce the amount of residual solvent in the polyimide film, and can produce high transmittance, low yellowness, and Polyimide film with high mechanical strength.

[Manufacturing method of polyimide resin] The production method of polyimide resin is not particularly limited. It is preferable to react diamine and acid dianhydride in a solvent to prepare polyimide as a precursor of polyimide, by dehydration of polyimide The method of cyclization and imidization. For example, an imidization catalyst and a dehydrating agent are added to the polyimide solution to dehydrate and close the polyimide ring, thereby obtaining a polyimide solution. The polyimide solution and the poor solvent for polyimine are mixed to precipitate the polyimide resin, and the solid-liquid separation is performed, thereby obtaining the polyimide resin.

＜Preparation of polyamide acid＞ By reacting acid dianhydride and diamine in a solvent, a polyamide acid solution is obtained. For the polymerization of polyamide acid, an organic solvent that can dissolve the diamine and acid dianhydride as the raw material and the polyamide acid as the polymerization product can be used without particular limitation. Specific examples of organic solvents include urea-based solvents such as methyl urea and N,N-dimethyl ethyl urea; sulfide-based solvents such as dimethyl sulfide, diphenyl sulfide, and tetramethyl sulfide; N,N -Dimethylacetamide, N,N-dimethylformamide, N,N'-diethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, hexamethyl Amine-based solvents such as triamine phosphate; halogenated alkane-based solvents such as chloroform and dichloromethane; aromatic hydrocarbon-based solvents such as benzene and toluene, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxolane, etc. Ether solvents such as alkane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These solvents may be used alone, or two or more of them may be appropriately combined and used. Among them, since the polymerization reactivity and the solubility of polyamic acid are excellent, it is preferable to use N,N-dimethylacetamide, N,N-dimethylformamide, or N- Methylpyrrolidone.

By dissolving diamine and acid dianhydride in an organic solvent, the polymerization of polyamide acid proceeds. The solid content concentration of the polyamide acid solution (the added concentration of diamine and acid dianhydride in the reaction solution) is usually about 5-40% by weight, preferably 10-30% by weight. The acid dianhydride and diamine are preferably used in equal molar amounts (95:105 to 105:95). If a certain component is excessive, the molecular weight of polyimide and polyimide may not be sufficiently increased, and the mechanical strength of the polyimide film may decrease.

The reaction temperature is not particularly limited, but is preferably 0°C or higher and 80°C or lower, more preferably 20°C or higher and 45°C or lower. By setting it to 0°C or higher, the reduction in the reaction rate can be suppressed and the polymerization reaction can be carried out in a relatively short time. In addition, by setting it to 80°C or less, it is possible to suppress a decrease in the degree of polymerization caused by ring opening of the acid dianhydride component.

The order of addition of the diamine and acid dianhydride to the organic solvent (reaction system) in the polymerization of polyamide acid is not particularly limited. The arrangement of the monomer components (structure derived from acid dianhydride and structure derived from diamine) in polyamide acid and polyimine can be random or block.

After either the total amount of diamine or the total amount of acid dianhydride is dissolved or dispersed in an organic solvent in a slurry form, the other is added to obtain a random polyamide acid. For example, the diamine is dissolved or dispersed in an organic solvent in the form of a slurry to prepare a diamine solution, and the acid dianhydride is added to the diamine solution. Diamine can also be added to the solution which melt|dissolved acid dianhydride in an organic polar solvent. Multiple acid dianhydrides and diamines can be added at one time or added in multiple times. Diamine and acid dianhydride can be added in a solid state, and can also be added in a state of being dissolved or dispersed in an organic solvent in the form of a slurry.

By adjusting the order of monomer addition, various physical properties of the obtained polyimide can also be controlled. For example, in (A) a plurality of acid dianhydrides and diamines, a specific acid dianhydride and diamine are first reacted to form a structural unit (repeating unit) formed by bonding the specific acid dianhydride and diamine The segment (oligomer). After adjusting the oligomer, (B) add the remaining part of the diamine and the acid dianhydride, and then perform the reaction (post-polymerization), thereby obtaining a polyamide acid containing a block structure in the molecule. The polyimide is obtained by imidizing the polyimide to obtain a polyimide containing a continuous block of structural units formed by bonding a specific diamine and a specific acid dianhydride in the molecular structure. When the polyimide has a block structure, the mechanical strength or heat resistance of the polyimide film tends to increase.

In the above step (A), an excess of either the acid dianhydride and the diamine is allowed to react, thereby forming an oligomer at the acid anhydride terminal or the amine terminal. The addition amount of acid dianhydride and diamine in the preparation of oligomer relative to the total addition amount (the total addition amount of (A) and (B)) is preferably 70 to 95 mol%, more preferably 75 to 90 mol%.

In the preparation of oligomers, if the addition amount of diamine is greater than the addition amount of acid dianhydride, an amine-terminated oligomer is formed. In the case of preparing amine-terminated oligomers, the amount of diamine added relative to the amount of acid dianhydride added is preferably 1.01 to 1.25 times in molar ratio, more preferably 1.03 to 1.2 times, and even more preferably 1.05 ~ 1.18 times. The closer the ratio of the two is to 1, the larger the molecular weight of the oligomer tends to be.

In the preparation of oligomers, it is preferable to include benzidine substituted with fluoroalkyl groups such as TFMB as the diamine, acid dianhydrides represented by general formula (1) such as TAHMBP, and acids containing cyclobutane structure such as CBDA The dianhydride is used as the acid dianhydride. In particular, it is preferable to use only benzidine substituted with a fluoroalkyl group as the diamine. 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 remaining part of diamine and acid dianhydride is added in such a way that the total addition amount of diamine and the total addition amount of acid dianhydride is equal to the molar amount (95:105～105:95) , The end of the oligomer prepared in step (A) above reacts with the monomer added in step (B) to obtain polyamide acid with an alternating block structure. The polyimide is obtained by imidizing the polyimide to obtain a polyimide containing a continuous block of structural units formed by bonding a specific diamine and a specific acid dianhydride in the molecular structure.

In step (B), the remaining part of the acid dianhydride and diamine can be added simultaneously or sequentially. It is also possible to add the oligomer obtained by reacting the remaining part of the acid dianhydride with the diamine in advance to the solution of the oligomer prepared in (A).

＜Iimidization＞ Polyimide is obtained by dehydration and cyclization of polyamide. The chemical imidization method of adding a dehydrating agent and an imidization catalyst to the polyamide solution is suitable for imidization in the solution. In order to promote the progress of the imidization, the polyamide acid solution can also be heated.

As the imidization catalyst, tertiary amines can be used. As the tertiary amine, a heterocyclic tertiary amine is preferred. Specific examples of heterocyclic tertiary amines include pyridine, picoline, quinoline, isoquinoline, and the like. As the dehydrating agent, carboxylic anhydride can be used, and specifically, acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, etc. can be mentioned. The addition amount of the imidization catalyst relative to the amide group of the polyamide acid is preferably 0.5 to 5.0 times molar equivalent, more preferably 0.7 to 2.5 times molar equivalent, and still more preferably 0.8 to 2.0 times molar equivalent Molar equivalent. The amount of the dehydrating agent added is preferably 0.5 to 10.0 molar equivalents, more preferably 0.7 to 5.0 molar equivalents, and still more preferably 0.8 to 3.0 molar equivalents relative to the amide group of the polyamide acid.

＜Precipitation of polyimide resin＞ The polyimide solution obtained by the imidization of polyimide acid can also be directly used as a coating for film formation, but it is preferable to temporarily precipitate the polyimide resin in the form of a solid substance. By precipitating the polyimide resin as a solid substance, it is possible to clean and remove impurities or residual monomer components generated during the polymerization of polyimide acid, as well as dehydrating agents and imidization catalysts. Therefore, a polyimide film excellent in transparency and mechanical properties can be obtained.

By mixing the polyimide solution with the poor solvent, the polyimide resin is precipitated. The poor solvent is a poor solvent for the polyimide resin, and is preferably mixed with a solvent that dissolves the polyimide resin, and examples thereof include water, alcohols, and the like. Examples of alcohols include methanol, ethanol, isopropanol, ethylene glycol, triethylene glycol, 2-butanol, 2-hexanol, cyclopentanol, cyclohexanol, phenol, and tertiary butanol. As far as the ring opening of polyimine is difficult to occur, alcohols such as isopropanol, 2-butanol, 2-pentanol, phenol, cyclopentanol, cyclohexanol, and tert-butanol are preferred, and particularly preferred It is isopropanol.

[Polyimide film] A polyimide solution (film-forming coating) prepared by dissolving polyimide resin in an organic solvent is coated on a substrate, and the solvent is dried and removed, thereby producing a polyimide film.

The organic solvent for dissolving the polyimide resin is not particularly limited as long as it can dissolve the above-mentioned polyimide resin. As the solvent is easily removed by drying and can reduce the amount of residual solvent in the polyimide film, low boiling point solvents such as dichloromethane, methyl acetate, tetrahydrofuran, acetone, and 1,3-dioxolane are preferred Among them, dichloromethane is particularly preferred. As described above, by setting the composition ratio of the acid dianhydride component and the diamine component within a predetermined range, a polyimide showing high solubility in low-boiling solvents such as dichloromethane can be obtained.

The solid content concentration of the polyimide solution can be appropriately set according to the molecular weight of the polyimide, the thickness of the film, or the film forming environment. The solid content concentration is preferably 5 to 30% by weight, more preferably 8 to 20% by weight.

The polyimide solution may also contain resin components or additives other than polyimine. Examples of additives include ultraviolet absorbers, crosslinking agents, dyes, surfactants, leveling agents, plasticizers, fine particles, and the like. The content of the polyimide resin relative to 100 parts by weight of the solid content of the polyimide solution (film coating) is preferably 60 parts by weight or more, more preferably 70 parts by weight or more, and still more preferably 80 parts by weight the above.

As a method of applying the polyimide solution to the substrate, a known method can be used, for example, the coating can be carried out by a bar coater or a chipped wheel coater. As the base material for coating the polyimide solution, glass substrates, metal substrates such as SUS (Steel Use Stainless, stainless steel), metal rollers, metal belts, plastic films, etc. can be used. From the viewpoint of improving productivity, it is preferable to use an endless support such as a metal roller or a metal belt, or a long plastic film as a support, and to manufacture a film by roll-to-roll. When a plastic film is used as a support, it is sufficient to appropriately select a material that does not dissolve in the solvent of the film-making coating. As the plastic material, polyethylene terephthalate, polycarbonate, polyacrylate, and polycarbonate can be used. Ethylene naphthalate and so on.

It is preferable to heat when drying the solvent. The heating temperature is not particularly limited, but from the viewpoint of suppressing coloration, it is preferably 200°C or lower, and more preferably 180°C or lower. During the drying of the solvent, the heating temperature can also be increased stepwise. The solvent can also be dried under reduced pressure. The above-mentioned polyimide resin is soluble in low-boiling solvents such as dichloromethane, so even under heating at 200°C or less, the residual solvent can be easily reduced.

The residual solvent amount of the polyimide film (the mass of the solvent contained in the film relative to the mass of the film) is preferably 1.5% or less, more preferably 1.0% or less. If the residual solvent amount is in this range, the mechanical strength of the polyimide film tends to increase.

The thickness of the polyimide film is not particularly limited, and can be appropriately set according to the application. The thickness of the polyimide film is, for example, about 5 to 100 μm. In applications requiring impact resistance such as cover window materials for displays, 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 40 μm or more. From the viewpoint of maintaining excellent transparency, the thickness of the polyimide film is preferably 90 μm or less, more preferably 85 μm or less.

[Characteristics of Polyimide Film] The yellowness (YI) of the polyimide film is preferably 3.0 or less, more preferably 2.5 or less. When the yellowness is 3.0 or less, the film is not colored yellow and can be preferably used as a film for displays and the like.

The total light transmittance of the polyimide film is preferably 80% or more, more preferably 85% or more. In addition, the light transmittance of the polyimide film at a wavelength of 400 nm is preferably 35% or more, and more preferably 40% or more. The tensile elastic modulus of the polyimide film is preferably 4.9 GPa or more, more preferably 5.0 GPa or more, and still more preferably 5.2 GPa or more.

From the viewpoint of preventing damage to the film caused by contact with the roll during roll-to-roll transport, or contact between the films during winding, the pencil hardness of the polyimide film is preferably HB or higher, more preferably Above F. When the polyimide film is used in the cover window of a display, etc., since the scratch resistance to contact from the outside is required, the pencil hardness of the polyimide film is preferably H or higher.

[Use of polyimide film] The polyimide film of the present invention has low yellowness and high transparency, and can be preferably used as a display material. In particular, the polyimide film with higher mechanical strength can be applied to surface members such as cover windows of displays. In practical applications, the polyimide film of the present invention can be provided with an antistatic layer, an easy bonding layer, a hard coating layer, an anti-reflection 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 polyamide acid solution] <The polymerization of random bodies: Examples 3, 10-12, Comparative Examples 1, 7, and 8> Put N,N-dimethylformamide as a solvent in a separable flask, while stirring under a nitrogen atmosphere, put the molar ratio of diamine and acid dianhydride shown in the composition A of Table 1 into the nitrogen atmosphere while stirring. Stir in the atmosphere for 5 hours to obtain a polyamide acid solution with a solid content of 18%.

<Block polymerization: Examples 1, 2, 4-9, Comparative Examples 2-6> Put N,N-dimethylformamide as a solvent in a separable flask, while stirring under a nitrogen atmosphere, put the molar ratio of diamine and acid dianhydride shown in the composition A of Table 1 into the nitrogen atmosphere while stirring. Stir under the atmosphere for 10 hours to synthesize oligomers. After that, diamine and acid dianhydride were added in the molar ratio shown in composition B of Table 1, stirred for a predetermined time under a nitrogen atmosphere, and then polymerized to obtain a polyamide acid solution with a solid content of 18%.

The abbreviations of the raw monomers shown in Table 1 are as follows. TMHQ: p-phenylene bistrimellitic dianhydride TAHMBP: Bis (1,3-di-side oxy-1,3-dihydroisobenzofuran-5-carboxylic acid) 2,2',3,3',5,5'-hexamethylbiphenyl- 4,4'-diester 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-cyclobutane tetracarboxylic dianhydride TFMB: 2,2'-bis(trifluoromethyl)benzidine 3,3'-DDS: 3,3'-diaminodiphenyl sulfide 4,4'-DDS: 4,4'-diaminodiphenyl sulfide

[Preparation of imidization, isolation of polyimide resin, and polyimide solution] 5.5 g of pyridine as an imidization catalyst was added to 100 g of the polyamide acid solution to completely disperse it, and then 8 g of acetic anhydride was added, and the mixture was stirred at 90°C for 3 hours to perform imidization. If the solution is not gelled, while stirring the solution cooled to room temperature, add 100 g of 2-propanol (hereinafter referred to as "IPA") dropwise at a rate of 2 to 3 drops/sec to precipitate the polyimide . Furthermore, 150 g of IPA was added, and after stirring for about 30 minutes, a Kiriyama funnel was used for suction filtration. The obtained solid was washed with 100 g of IPA. After the washing operation was repeated 6 times, it was dried in a vacuum oven set at 120°C for 8 hours to obtain a polyimide resin. Furthermore, in Comparative Examples 1 to 5, the viscosity of the solution increased sharply during the imidization and gelled, so that the polyimide solution could not be obtained. Therefore, in these comparative examples, subsequent operations and evaluations are not implemented.

9 g of dichloromethane (DCM) was added to 1 g of the polyimide resin obtained above, and after stirring for 12 hours at room temperature, the presence or absence of the dissolved residue was visually confirmed to determine the effect of the polyimide resin The solubility of DCM was evaluated. The one that obtained a transparent solution under visual observation was set as DCM "soluble", and the one that was confirmed to dissolve the residue in the form of solid content was set as DCM "insoluble". In addition, in the case where gelation occurs during imidization, it is described as "gelation" in Table 1.

[Production of polyimide film] The polyimide resin was dissolved in dichloromethane (hereinafter referred to as "DCM") to obtain a polyimide solution with a solid content concentration of 10% by weight. Use a bar coater to coat the polyimide solution on an alkali-free glass plate, and heat it at 40°C for 60 minutes, 80°C for 30 minutes, 150°C for 30 minutes, and at 170°C in the atmosphere. Heat at ℃ for 30 minutes to remove the solvent, and obtain a polyimide film with the thickness shown in Table 1. Furthermore, since the polyimide resin of Comparative Example 8 was not dissolved in DCM, a polyimide solution obtained by dissolving the polyimide resin in methyl ethyl ketone (MEK) was used to produce a film.

[Evaluation of Polyimide Film] (Tensile modulus of elasticity) The measurement uses "AUTOGRAPH AGS-X" manufactured by Shimadzu Corporation under the following conditions. Sample measurement range: width 10 mm, distance between clamps 100 mm, stretching speed: 20.0 mm/min, measurement temperature: 23°C. The sample is obtained by standing for 1 day at 23℃/55%RH and adjusting the humidity.

(Yellowness) Using a sample with a size of 3 cm square, the yellowness (YI) was measured with a spectrophotometer "SC-P" manufactured by Suga Test Instruments.

(Pencil hardness) Measure the pencil hardness of the film by JIS K-5600-5-4 "Pencil Scratch Test".

(Transmittance at 400 nm) Use the UV-Vis spectrophotometer "V-560" manufactured by JASCO Corporation to measure the light transmittance of the film at 300-800 nm, and read the light transmittance at the wavelength of 400 nm.

(Total light transmittance) The haze meter "HZ-V3" manufactured by Suga Test Instruments was used to measure by the method described in JIS K7361-1.

(Amount of remaining solvent) Using about 8.9 g of 1,3-dioxolane as a solvent, dissolving about 0.1 g of a polyimide film and about 1 g of diethylene glycol butyl methyl ether (DEGBME) as an internal standard material, and preparing the measurement Sample. The solution was measured using a gas chromatography device (GC, manufactured by Shimadzu Corporation), and the amount of residual solvent (DCM or MEK) contained in the polyimide membrane was determined from the GC peak area and preparation concentration.

The composition of the polyimide resin of the above-mentioned examples and comparative examples (the molar ratio of the acid dianhydride and diamine in the polymerization of polyamide acid), the solubility to DCM, and the film formation of the film The solvents used and the evaluation results of the polyimide film are shown in Table 1.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Comparative example 8 Polymer sequence Block Block Random Block Block Block Block Block Block Random Random Random Random Block Block Block Block Block Random Random composition A Diamine TFMB 90 90 90 90 90 90 90 90 90 90 100 70 100 90 90 60 90 100 100 70 3,3'-DDS - 3.3 10 - - - - - 3.3 10 - 30 - - - - - - - 30 Acid dianhydride TAHMBP 50 50 50 50 45 50 50 40 40 40 70 70 50 50 35 25 - 45 100 - TMHQ - - - - - - - - - - - - - - - - 50 - - - BPDA - - - - 15 15 15 20 20 20 15 15 40 30 30 25 15 25 - CBDA 30 30 30 30 20 15 15 20 20 20 15 15 10 - 15 - 15 - - 60 6FDA - - 20 - - - - - - 20 40 B Diamine TFMB - - - - - - - - 10 10 10 - 3,3'-DDS 10 6.7 - 10 10 - 10 6.7 - - 30 10 - 4,4'-DDS - - 10 - - 10 - - - - - - - Acid dianhydride 6FDA 20 20 20 20 20 20 20 20 20 20 50 20 30 DCM solubility Soluble Soluble Soluble Soluble Soluble Soluble Soluble Soluble Soluble Soluble Soluble Soluble Gelation Gelation Gelation Gelation Gelation Soluble Soluble Insoluble Solvent for film making DCM DCM DCM DCM DCM DCM DCM DCM DCM DCM DCM DCM DCM DCM MEK Membrane characteristics Film thickness mm 56 54 50 50 50 49 51 50 50 50 54 55 54 50 49 Tensile modulus of elasticity GPa 5.7 5.5 5.1 5.6 5.2 5.4 5.2 5.6 5.2 5.0 5.3 5.0 4.6 4.8 4.1 Pencil hardness - 4H 4H 4H 4H 4H 4H 4H 4H 4H 3H 4H 3H 3H 4H 3H YI - 2.3 2.3 2.1 2.3 2.2 2.5 2.4 2.3 2.3 2.2 2.8 2.7 2.7 2.6 1.9 Transmittance at 400 nm % 58.2 60.3 62.1 60.4 52.5 51.9 51.1 50.0 51.1 51.7 45.7 46.6 45.1 51.2 81.7 Total light transmittance % 89.5 89.8 89.5 89.5 89.5 89.3 89.3 89.2 89.2 89.3 89.1 88.8 89.1 89.2 91.0 Residual solvent volume % ND ND 0.1 0.2 ND ND 0.2 ND 0.1 0.2 ND 0.1 0.6 0.1 2.8

As shown in Table 1, it can be seen that in Examples 1-12, the polyimide exhibits DCM solubility, and the polyimide film exhibits a tensile modulus of 5 GPa or more, which can have both excellent mechanical strength and transparency.

In Comparative Example 1 where the amount of CBDA relative to the total amount of acid dianhydride is 10 mol%, the solvent solubility of polyimine is low, and the solution gels during imidization, so the polyimide cannot be made Amine resin is isolated. In Comparative Example 2 without CBDA, Comparative Example 3 in which the amount of TAHMBP is 35 mol%, and Comparative Example 4 in which the amount of TAHMBP is 25 mol%, the same as in Comparative Example 1, occurs during imidization Gelation.

In Comparative Example 5 in which TMHQ, which is trimellitic dianhydride ester, was used as acid dianhydride, gelation also 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 the combination of CBDA and 6FDA as the acid dianhydride, although gelation did not occur during imidization, the isolated polyimid did not show DCM solubility. Although the polyimide film of Comparative Example 8 obtained by forming a film using MEK as a solvent showed excellent transparency, the tensile modulus of elasticity was 4.1 GPa, which was inferior in mechanical strength compared with the examples. In addition, in Comparative Example 8, the residual solvent amount of MEK was 2.8%, which was larger than that of other examples using DCM. In Comparative Example 8, since DCM as a low boiling point solvent cannot be used, it is not easy to obtain a polyimide film with a small amount of residual solvent. To reduce the amount of residual solvent, it is necessary to extend the heating time, and the productivity of the polyimide film is not easy to improve. .

In Comparative Example 6 and Comparative Example 7, although CBDA was not used as the acid dianhydride, the introduction ratio of TAHMBP and 6FDA was increased, thereby obtaining a polyimide resin soluble in DCM. However, the tensile elastic modulus of the polyimide films of Comparative Examples 6 and 7 was lower than 5 GPa, and the mechanical strength was insufficient.

From the above results, it can be seen that the diamine component contains benzidine substituted with a fluoroalkyl group, the ester of biphenol with a substituent on the benzene ring and trimellitic dianhydride, and a cyclobutane structure. The acid dianhydride as the polyimide of the acid dianhydride is soluble in low-boiling solvents such as DCM, so it can easily produce a film with a small amount of residual solvent, and it can have both the mechanical properties and transparency of the polyimide film .

From the comparison of Examples 1 and 2 with Example 3, and the comparison between Examples 8, 9 and Example 10, it can be seen that the polyimide with block structure is compared with the polyimide with random structure of the same composition , Showing a higher modulus of elasticity. In particular, in Examples 1 and 8 in which blocks containing only TFMB as the diamine component were formed, the tensile elastic modulus of the polyimide film tends to increase.

Claims (16)

A polyimide resin having a structure derived from acid dianhydride and a structure derived from diamine, and as the above-mentioned diamine, relative to the total amount of diamine 100 mol%, it contains benzidine substituted by fluoroalkyl group 40 ～100 mol% or less, as the above-mentioned acid dianhydride, relative to 100 mol% of the total amount of acid dianhydride, containing 40 to 85 mol% or less of the acid dianhydride represented by the general formula (1), and an acid having a cyclobutane structure Less than 15～60 mol% of dianhydride, [Chemical 1]

In the general formula (1), R ¹ to R ⁸ are each independently a hydrogen atom, an alkyl group with 1 to 20 carbon atoms, or a perfluoroalkyl group with 1 to 20 carbon atoms, and one of R ¹ to R ⁴ One or more and one or more of R ⁵ to R ⁸ are alkyl groups having 1 to 20 carbon atoms or fluoroalkyl groups having 1 to 20 carbon atoms. The polyimide resin of claim 1, wherein the acid dianhydride represented by the general formula (1) is a compound represented by the formula (2), [化2]

. The polyimide resin of 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 above-mentioned benzidine substituted with a fluoroalkyl group is 2,2'-bis(trifluoromethyl)benzidine. The polyimide resin according to any one of claims 1 to 4, wherein as the above-mentioned acid dianhydride, it further comprises 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3, 3,3-hexafluoropropane dianhydride. The polyimide resin according to any one of claims 1 to 5, which further contains 3,3',4,4'-biphenyltetracarboxylic dianhydride as the above-mentioned acid dianhydride. The polyimide resin according to any one of claims 1 to 6, wherein as the above-mentioned diamine, it further contains 5-40 mol% of diaminodiphenyl sulfide. A method for manufacturing a polyimide resin, which is the method for manufacturing a polyimide resin according to any one of claims 1 to 7, and The above-mentioned diamine and the above-mentioned acid dianhydride are reacted in a solvent to prepare a polyamide acid solution, A dehydrating agent and an imidization catalyst are added to the polyamide acid solution, so that the polyamide acid is imidized. Such as claim 8 of the manufacturing method of polyimide resin, wherein the polyimide solution in which polyimide is dissolved in an organic solvent is mixed with the poor solvent of polyimide to precipitate the polyimide resin . Such as claim 8 or 9 of the manufacturing method of polyimide resin, wherein In the preparation of the above polyamide acid solution, (A) Make any one of acid dianhydride and diamine excessively react to adjust the oligomer of acid anhydride terminal or amine terminal, (B) The remaining part of the diamine and the acid dianhydride is added so that the total addition amount of the diamine and the total addition amount of the acid dianhydride are equal molar amounts to perform post-polymerization. Such as claim 8 or 9 of the manufacturing method of polyimide resin, wherein In the preparation of the above polyamide acid solution, After dissolving or dispersing any 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 polyimide film comprising the polyimide resin according to any one of claims 1 to 7. For example, the polyimide film of claim 12 has a tensile elastic modulus of 5.0 GPa or more. For example, the polyimide film of claim 12 or 13 has a pencil hardness of H or higher. For example, the polyimide film of any one of claims 12 to 14 has a yellowness of 3.0 or less. A method for manufacturing a polyimide film, which is to coat a polyimide solution obtained by dissolving the polyimide resin of any one of claims 1 to 7 in a solvent containing dichloromethane on a base Material, and remove the above solvent.