CN118215713A - Resin composition, molded article and film - Google Patents

Abstract

The resin composition includes polyimide and an acrylic resin. The polyimide contains fluorine-containing aromatic tetracarboxylic dianhydride and fluorine-free aromatic tetracarboxylic dianhydride as tetracarboxylic dianhydride components, and fluoroalkyl-substituted benzidine as diamine component. The amount of the fluorine-containing aromatic tetracarboxylic dianhydride is preferably 30 to 90 mol% and the amount of the fluorine-free aromatic tetracarboxylic dianhydride is preferably 10 to 70 mol% based on the total amount of the tetracarboxylic dianhydride component of the polyimide. The amount of fluoroalkyl-substituted benzidine is preferably 25 mol% or more relative to the total amount of diamine components of the polyimide.

Description

Resin composition, molded article and film

Technical Field

The present invention relates to a resin composition and a molded article such as a film.

Background

In display devices such as liquid crystal, organic EL (Electroluminescence), and electronic paper, and in electronic devices such as solar cells and touch panels, there is a demand for thickness reduction, weight reduction, and flexibility. By replacing the glass material used in these devices with a thin film material, flexibility, thickness, and weight can be achieved. As a glass substitute material, a transparent polyimide film has been developed, and is used for a substrate for a display, a cover film, or the like.

The usual polyimide film can be obtained by: the polyamic acid solution as a polyimide precursor is applied as a film on a support, and subjected to a high-temperature treatment to remove the solvent, while performing thermal imidization. However, the high heating temperature (for example, 300 ℃ or higher) used for thermal imidization tends to cause coloration (increase in yellowness) due to heating, and is difficult to apply to applications requiring high transparency such as a cover film for a display.

As a method for producing a polyimide film having high transparency, a method has been proposed in which a polyimide resin which is soluble in an organic solvent and does not require imidization at a high temperature after film formation is used. For example, patent document 1 describes that polyimide containing bis (trimellitic anhydride) esters as tetracarboxylic dianhydride components is soluble in a low boiling point solvent such as methylene chloride and is excellent in transparency and mechanical strength.

Prior art literature

Patent literature

Patent document 1: international publication No. 2020/004236

Disclosure of Invention

Problems to be solved by the invention

When a polyimide is introduced into a rigid structure, the mechanical strength is improved, but the solubility in an organic solvent or the transparency is reduced, and it is difficult for conventional transparent polyimide resins to have both transparency and high mechanical strength while maintaining the transparency. In view of the above problems, an object of the present invention is to provide a molded article such as a film having high transparency and sufficient mechanical strength, and a resin composition for producing the same.

Solution for solving the problem

The present inventors have found that a polyimide having a specific chemical structure exhibits compatibility with an acrylic resin, and that a resin composition containing the polyimide and the acrylic resin can be used to produce a film having high transparency without impairing the excellent mechanical strength of the polyimide, thereby solving the above-mentioned problems.

One embodiment of the present invention relates to a film and a resin composition each comprising a polyimide resin and an acrylic resin. The resin composition may contain a polyimide resin and an acrylic resin in a weight ratio ranging from 98:2 to 2:98.

The polyimide contains fluorine-containing aromatic tetracarboxylic dianhydride and fluorine-free aromatic tetracarboxylic dianhydride as tetracarboxylic dianhydride components, and fluoroalkyl-substituted benzidine as diamine component.

As a preferred example of the fluorine-containing aromatic tetracarboxylic dianhydride, 4' - (hexafluoroisopropylidene) diphthalic anhydride (6 FDA) is mentioned. As a preferred example of fluoroalkyl-substituted benzidine, 2' -bis (trifluoromethyl) benzidine can be cited.

Preferable examples of the fluorine-free tetracarboxylic dianhydride include: pyromellitic dianhydride (PMDA), trimellitic dianhydride (MPDA), 3', 4' -biphenyl tetracarboxylic dianhydride (BPDA), 4' -oxydiphthalic anhydride (ODPA), 3',4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 4' - (4, 4' -isopropylidenediphenoxy) diphthalic anhydride (BPADA), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), and bis (trimellitic anhydride) esters.

The amount of the fluorine-containing aromatic tetracarboxylic dianhydride is preferably 30 to 90 mol% and the amount of the fluorine-free aromatic tetracarboxylic dianhydride is preferably 10 to 70 mol% based on the total amount of the tetracarboxylic dianhydride component of the polyimide. The amount of fluoroalkyl-substituted benzidine is preferably 25 mol% or more relative to the total amount of diamine components of the polyimide.

The film according to one embodiment of the present invention has a thickness of 5 [ mu ] m to 300 [ mu ] m, a total light transmittance of 85% to 10%, a haze of 3.0 or less, a tensile elastic modulus of 3.0GPa to F, and a yellowness of F.

ADVANTAGEOUS EFFECTS OF INVENTION

Since the polyimide resin contained in the resin composition exhibits compatibility with the acrylic resin, a transparent film having a small haze can be obtained. Further, since the polyimide resin and the acrylic resin exhibit compatibility, coloring can be reduced without significantly deteriorating excellent mechanical strength of polyimide, and a transparent film suitable for a cover film of a display or the like can be produced.

Detailed Description

[ Resin composition ]

One embodiment of the present invention is a compatible resin composition comprising a polyimide resin and an acrylic resin.

< Polyimide >

The polyimide is obtained by: the polyamic acid obtained by the addition polymerization of a tetracarboxylic dianhydride (hereinafter, sometimes referred to as "acid dianhydride") and a diamine is subjected to dehydrative ring closure. That is, polyimide is a polycondensate of tetracarboxylic dianhydride and diamine, and has a structure derived from acid dianhydride (acid dianhydride component) and a structure derived from diamine (diamine component).

In addition to the method in which the polyimide is synthesized from the acid dianhydride and the diamine through the polyamic acid, the polyimide may be synthesized by condensation or the like of diisocyanate and the acid dianhydride due to decarbonation, and in any of the synthetic methods, the polyimide obtained has a structure derived from the acid dianhydride from which 4 carboxyl groups have been removed from the tetracarboxylic dianhydride (tetracarboxylic dianhydride residue) and a structure derived from the diamine from which 2 amino groups have been removed from the diamine (diamine residue). Therefore, when the starting material for synthesizing the polyimide is not acid dianhydride or diamine, the structure corresponding to the tetracarboxylic dianhydride residue contained in the polyimide is also referred to as "acid dianhydride component", and the structure corresponding to the diamine residue is referred to as "diamine component".

The polyimide used in the present embodiment is preferably soluble in an organic solvent, and is preferably dissolved in N, N-Dimethylformamide (DMF) at a concentration of 1 wt% or more. Polyimide is particularly preferably polyimide which is soluble in a non-amide solvent other than an amide solvent such as DMF.

(Acid dianhydride)

The polyimide used in the present embodiment contains a fluorine-containing aromatic tetracarboxylic dianhydride as a structure derived from a tetracarboxylic dianhydride, and further contains at least 1 fluorine-free aromatic tetracarboxylic dianhydride as a structure derived from a tetracarboxylic dianhydride. The fluorine-containing tetracarboxylic dianhydride and the fluorine-free aromatic tetracarboxylic dianhydride may each contain 2 or more.

By containing a fluorine-containing aromatic tetracarboxylic dianhydride as an acid dianhydride component, the transparency of polyimide and the solubility in an organic solvent tend to be improved. By containing an aromatic tetracarboxylic dianhydride which does not contain fluorine as an acid dianhydride component, the mechanical strength of the polyimide can be improved. In addition, the compatibility of polyimide with acrylic resin is improved according to the kind of fluorine-free aromatic tetracarboxylic dianhydride.

The fluorine-containing aromatic tetracarboxylic dianhydride includes: 4,4' - (hexafluoroisopropylidene) diphthalic anhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, 1, 4-difluoro pyromellitic dianhydride, 1, 4-bis (trifluoromethyl) pyromellitic dianhydride, 4-trifluoromethyl pyromellitic dianhydride, 3, 6-bis [3',5' -bis (trifluoromethyl) phenyl ] pyromellitic dianhydride, 1- (3 ',5' -bis (trifluoromethyl) phenyl) pyromellitic dianhydride, and the like. Among them, 4' - (hexafluoroisopropylidene) diphthalic anhydride (6 FDA) is particularly preferred from the viewpoint of both transparency and mechanical strength of polyimide.

Examples of the fluorine-free aromatic tetracarboxylic dianhydride include: acid dianhydrides having 2 acid anhydride groups bonded to 1 benzene ring such as pyromellitic dianhydride and trimellitic dianhydride; acid dianhydrides having 2 acid anhydride groups bonded to 1 condensed polycyclic ring such as 2,3,6, 7-naphthalene tetracarboxylic acid 2,3:6, 7-dianhydride, naphthalene-1, 4,5, 8-tetracarboxylic acid dianhydride, and terphenyl tetracarboxylic acid dianhydride; bis (trimellitic anhydride) ester, 3',4' -biphenyltetracarboxylic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride, 3',4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4' - (4, 4' -isopropylidenediphenoxy) diphthalic anhydride, 5' -dimethylmethylenebis (phthalic anhydride), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, 11-dimethyl-1H-difluoro [3,4-b:3',4' -i ] xanthene-1, 3,7,9 (11H) -tetraone, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 4- (2, 5-dioxotetrahydrofuran-3-yl) -1,2,3, 4-tetrahydronaphthalene-1, 2-dicarboxylic acid dianhydride, ethylene glycol bis (trimellitic anhydride), N ' - (9H-fluoren-9-ylidenedi-4, 1-phenylene) bis [1, 3-dihydro-1, 3-dioxo-5-isobenzofuran carboxamide ], N ' - [ [2, 2-trifluoro-1- (trifluoromethyl) ethylidene ] bis (6-hydroxy-3, 1-phenylene) ] bis [1, 3-dihydro-1, 3-dioxo-5-isobenzofuran carboxamide ], 2-bis (4-hydroxyphenyl) propane dibenzoate-3, 3', acid dianhydrides having acid anhydride groups bonded to different aromatic rings such as 4,4' -tetracarboxylic dianhydride.

Among them, from the viewpoints of transparency and solubility of polyimide and compatibility with acrylic resin, pyromellitic dianhydride (PMDA), trimellitic dianhydride (MPDA), 3',4,4' -biphenyltetracarboxylic dianhydride (BPDA), 4' -oxydiphthalic anhydride (ODPA), 3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 4' - (4, 4' -isopropylidenediphenoxy) diphthalic anhydride (BPADA), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (BPAF), bis (trimellitic anhydride) ester.

The bis (trimellitic anhydride) ester is represented by the following general formula (1).

X in the general formula (1) is any divalent organic group, and carboxyl groups are bonded to carbon atoms of X at both ends of X. The carbon atom bonded to the carboxyl group may form a ring structure. Specific examples of the divalent organic group X include the following (A) to (K).

R ¹ in the formula (A) is a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and m is an integer of 0 to 4. The group represented by the formula (A) is a group obtained by removing 2 hydroxyl groups from a hydroquinone derivative which may have a substituent on the benzene ring. Examples of hydroquinone having a substituent on the benzene ring include: tertiary butyl hydroquinone, 2, 5-di-tertiary amyl hydroquinone, and the like. In the general formula (1), when X is (a) and m=0 (i.e., there is no substituent on the benzene ring), the bis (trimellitic anhydride) ester is p-phenylene bis (trimellitic anhydride) (abbreviated as TAHQ).

R ² in the formula (B) is a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and n is an integer of 0 to 4. The group represented by the formula (B) is a group obtained by removing 2 hydroxyl groups from biphenol which may have a substituent on the benzene ring. Examples of the diphenol derivative having a substituent on the benzene ring include: 2,2' -dimethylbiphenyl-4, 4' -diol, 3',5,5' -tetramethylbiphenyl-4, 4' -diol, 2', 3', 5' -hexamethylbiphenyl-4, 4' -diol, and the like.

The group represented by the formula (C) is a group obtained by removing 2 hydroxyl groups from 4,4' -isopropylidenediphenol (bisphenol A). The group represented by the formula (D) is a group obtained by removing 2 hydroxyl groups from resorcinol.

P in the formula (E) is an integer of 1 to 10. The group represented by the formula (E) is a group obtained by removing 2 hydroxyl groups from a linear diol having 1 to 10 carbon atoms. Examples of the linear diol having 1 to 10 carbon atoms include: ethylene glycol, 1, 4-butanediol, and the like.

The group represented by the formula (F) is a group obtained by removing 2 hydroxyl groups from 1, 4-cyclohexanedimethanol.

R ³ in the formula (G) is a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and q is an integer of 0 to 4. The group represented by the formula (G) is a group obtained by removing 2 hydroxyl groups from bisphenol fluorene having a substituent on a benzene ring which may have a phenolic hydroxyl group. Examples of bisphenol fluorene derivatives having a substituent on a benzene ring having a phenolic hydroxyl group include bisphenol fluorene and the like.

The bis (trimellitic anhydride) ester is preferably an aromatic ester. As X, among the above-mentioned (A) to (K), preferred are (A) (B) (C) (D) (G) (H) (I). Among them, (a) to (D) are preferable, and (B) is particularly preferable. When X is a group represented by the general formula (B), X is preferably 2,2', 3',5 '-hexamethylbiphenyl-4, 4' -diyl represented by the following formula (B1) from the viewpoint of solubility of polyimide in an organic solvent.

The acid dianhydride in which X in the general formula (1) is a group represented by the formula (B1) is bis (1, 3-dioxo-1, 3-dihydroisobenzofuran-5-carboxylic acid) -2,2', 3',5 '-hexamethylbiphenyl-4, 4' -diyl ester (abbreviated as TAHMBP) represented by the following formula (3).

The content of the fluorine-containing aromatic tetracarboxylic dianhydride is preferably 30 to 90 mol%, more preferably 35 to 80 mol%, and even more preferably 40 to 75 mol% relative to 100 mol% of the total amount of the acid dianhydride component, from the viewpoint of improving the compatibility of the polyimide resin with the acrylic resin and having both the transparency and the mechanical strength of the molded article such as a film formed from the resin composition. From the same viewpoint, the content of the fluorine-free aromatic tetracarboxylic dianhydride is preferably 10 to 70 mol%, more preferably 20 to 65 mol%, and even more preferably 25 to 60 mol% relative to 100 mol% of the total amount of the acid dianhydride component.

As described above, the aromatic tetracarboxylic dianhydride not containing fluorine is preferably PMDA, MPDA, BPDA, ODPA, BTDA, BPADA, BPAF or bis (trimellitic anhydride) ester, and the total amount thereof is preferably 10 to 70 mol%, more preferably 20 to 65 mol%, and further preferably 25 to 60 mol%.

The amount of the fluorine-free aromatic tetracarboxylic dianhydride required for compatibility with the acrylic resin and mechanical strength may vary depending on the kind of the acid dianhydride. For example, PMDA has a rigid structure, and thus contributes significantly to the improvement of mechanical strength even in a small amount, but if the amount of PMDA exceeds 70 mol%, the solubility of polyimide in an organic solvent or the compatibility with an acrylic resin tends to be lowered. On the other hand, BPADA has a structure in which 2 benzene rings to which an acid anhydride group is bonded are bonded via 4,4' -isopropylidenediphenoxy, and the flexibility of the molecular chain is high, so that even when the amount of BPADA is large, the solubility or compatibility in an organic solvent is not easily lowered. By using PMDA and BPADA in combination as the fluorine-free aromatic tetracarboxylic dianhydride, the mixture of the polyimide resin and the acrylic resin can also exhibit compatibility in a low boiling point solvent such as methylene chloride. Further, molded articles such as films made of polyimide resins containing PMDA and BPADA as fluorine-free aromatic tetracarboxylic dianhydrides and mixtures of acrylic resins are also excellent in mechanical strength.

From the viewpoint of obtaining a polyimide having both of solubility in an organic solvent and compatibility with an acrylic resin, the total content of fluorine-containing aromatic tetracarboxylic dianhydride and fluorine-free aromatic tetracarboxylic dianhydride, i.e., the content of aromatic tetracarboxylic dianhydride is preferably 80 mol% or more, more preferably 85 mol% or more, or may be 90 mol% or more, 95 mol% or more, or 100%, with respect to 100 mol% of the total amount of acid dianhydride components. The total content of 6FDA, PMDA, MPDA, BPDA, ODPA, BTDA, BPADA, BPAF and bis (trimellitic anhydride) ester is preferably 80 mol% or more, more preferably 85 mol% or more, and may be 90 mol% or more, 95 mol% or more, or 100% relative to 100 mol% of the total amount of the acid dianhydride component. As bis (trimellitic anhydride) esters, TAHQ and TAHMBP are preferable, and TAHMBP is particularly preferable.

The polyimide may contain a non-aromatic tetracarboxylic dianhydride as a structure derived from the tetracarboxylic dianhydride. Examples of the non-aromatic tetracarboxylic dianhydride include alicyclic tetracarboxylic dianhydrides.

Examples of the alicyclic tetracarboxylic dianhydride include: 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 1,2,3, 4-cyclopentane tetracarboxylic dianhydride, 1,2,4, 5-cyclohexane tetracarboxylic dianhydride, 1 '-dicyclohexyl-3, 3',4 '-tetracarboxylic acid-3, 4,3',4 '-dianhydride, norbornane-2-spiro-alpha-cyclopentanone-alpha' -spiro-2 '-norbornane-5, 5',6,6 '-tetracarboxylic dianhydride, 2' -bisnorbornane-5, 5', 6' tetracarboxylic dianhydride, etc. From the viewpoints of transparency and mechanical strength of polyimide, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 1,2,3, 4-cyclopentane tetracarboxylic dianhydride, or 1,2,4, 5-cyclohexane tetracarboxylic dianhydride is preferable, and 1,2,3, 4-cyclobutane tetracarboxylic dianhydride is particularly preferable.

Examples of the tetracarboxylic dianhydride other than the above include: ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, and the like.

(Diamine)

The polyimide used in the present embodiment contains fluoroalkyl-substituted benzidine as a diamine component.

Examples of fluoroalkyl-substituted benzidine include: 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' -difluorobenzidine, 3' -difluorobenzidine, 2', 3-trifluorobenzidine, 2,3' -trifluorobenzidine, 2', 5-trifluorobenzidine, 2', 6-trifluorobenzidine, 2,3', 5-trifluorobenzidine, 2,3', 6-trifluorobenzidine, 2', 3' -tetrafluorobenzidine, 2', 5' -tetrafluorobenzidine, 2', 6' -tetrafluorobenzidine, 2', 3',6,6' -hexafluorobenzidine, 2', 3', 5',6,6' -octafluorobiphenyl amine, 2- (trifluoromethyl) benzidine, 3- (trifluoromethyl) benzidine, 2, 3-bis (trifluoromethyl) benzidine, 2, 5-bis (trifluoromethyl) benzidine, 2, 6-bis (trifluoromethyl) benzidine, 2,3, 5-tris (trifluoromethyl) benzidine, 2,3, 6-tris (trifluoromethyl) benzidine, 2,3,5, 6-tetrakis (trifluoromethyl) benzidine, 2' -bis (trifluoromethyl) benzidine, 3' -bis (trifluoromethyl) benzidine, 2', 3-tris (trifluoromethyl) benzidine, 2,3' -tris (trifluoromethyl) benzidine, 2,2', 5-tris (trifluoromethyl) benzidine, 2', 6-tris (trifluoromethyl) benzidine, 2,3', 5-tris (trifluoromethyl) benzidine, 2,3',6, tris (trifluoromethyl) benzidine, 2', 3' -tetrakis (trifluoromethyl) benzidine, 2',5,5' -tetrakis (trifluoromethyl) benzidine, 2', 6' -tetrakis (trifluoromethyl) benzidine, and the like.

In the fluoroalkyl-substituted benzidine, the fluoroalkyl group of the fluoroalkyl-substituted benzidine is preferably a perfluoroalkyl group from the viewpoint of both the solubility and transparency of the polyimide. As the perfluoroalkyl group, trifluoromethyl is preferable. Among them, from the viewpoints of solubility of polyimide in an organic solvent and compatibility with an acrylic resin, perfluoroalkyl-substituted benzidine having a perfluoroalkyl 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 trifluoromethyl groups at the 2-and 2' -positions of biphenyl, pi electron density is reduced due to electron withdrawing property of trifluoromethyl groups, and pi conjugation planarity is reduced due to bond torsion between 2 benzene rings of biphenyl due to steric hindrance of trifluoromethyl groups, so that short wavelength shift of absorption end wavelength occurs, and coloring of polyimide can be reduced.

The content of fluoroalkyl-substituted benzidine is preferably 25 mol% or more, more preferably 30 mol% or more, further preferably 40 mol% or more, particularly preferably 50 mol% or more, and may be 60 mol% or more, 70 mol% or more, 80 mol% or more, 85 mol% or more, or 90 mol% or more, based on 100 mol% of the total diamine component. When the fluoroalkyl-substituted benzidine content is high, coloring of the film tends to be suppressed, and mechanical strength such as pencil hardness and elastic modulus tends to be high.

The polyimide may contain a diamine other than fluoroalkyl-substituted benzidine as a diamine-derived structure. Examples of diamines other than fluoroalkyl-substituted benzidine include: 2, 4-diaminotoluene, 2, 5-diaminotoluene, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3 '-diaminodiphenyl ether, 3,4' -diaminodiphenyl ether, 4 '-diaminodiphenyl ether, 3' -diaminodiphenyl sulfide, and 3,4 '-diaminodiphenyl sulfide, 4' -diaminodiphenyl sulfide, 3 '-diaminodiphenyl sulfone, 3,4' -diaminodiphenyl sulfone, 4 '-diaminodiphenyl sulfone, 9-bis (4-aminophenyl) fluorene, 3' -diaminobenzophenone, 4,4 '-diaminobenzophenone, 3' -diaminodiphenylmethane, 4 '-diaminodiphenylmethane, 3,4' -diaminodiphenylmethane, 2-bis (3-aminophenyl) propane, 2-bis (4-aminophenyl) propane, and 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 1-bis (3-aminophenyl) -1-phenylethane, 1-bis (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 '-bis (3-aminophenoxy) biphenyl, 4' -bis (4-aminophenoxy) 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, 2, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 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 '-bis [4- (4-aminophenoxy) benzoyl ] diphenyl ether, 4' -bis [4- (4-amino- α, α -dimethylbenzyl) phenoxy ] benzophenone, 4 '-bis [4- (4-amino- α, α -dimethylbenzyl) phenoxy ] diphenyl sulfone, 4' -bis [4- (4-aminophenoxy) phenoxy ] diphenyl sulfone, 3 '-diamino-4, 4' -diphenoxybenzophenone, 3,3 '-diamino-4, 4' -biphenoxybenzophenone, 3 '-diamino-4-phenoxybenzophenone, 3' -diamino-4-biphenoxybenzophenone, 6 '-bis (3-aminophenoxy) -3, 3',3 '-tetramethyl-1, 1' -spirobiindane, 6 '-bis (4-aminophenoxy) -3, 3',3 '-tetramethyl-1, 1' -spirobiindane, 1, 3-bis (3-aminopropyl) tetramethyl disiloxane, 1, 3-bis (4-aminobutyl) tetramethyl disiloxane, alpha, omega-bis (3-aminopropyl) polydimethylsiloxane, Alpha, omega-bis (3-aminobutyl) polydimethylsiloxanes, bis (aminomethyl) ethers, bis (2-aminoethyl) ethers, bis (3-aminopropyl) ethers, bis (2-aminomethoxy) ethyl ] ethers, bis [2- (2-aminoethoxy) ethyl ] ethers, bis [2- (3-aminopropoxy) ethyl ] ethers, 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, ethyleneglycol bis (3-aminopropyl) ethers, diethyleneglycol bis (3-aminopropyl) ethers, Triethylene glycol bis (3-aminopropyl) 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-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-diamino-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-tetrakis (trifluoromethyl) benzene.

For example, in addition to fluoroalkyl-substituted benzidine, diaminodiphenyl sulfone is used as a diamine, so that the solubility or transparency of polyimide in an organic solvent may be improved. Among the diaminodiphenyl sulfones, 3 '-diaminodiphenyl sulfone (3, 3' -DDS) and 4,4 '-diaminodiphenyl sulfone (4, 4' -DDS) are preferable. A combination of 3,3'-DDS and 4,4' -DDS may be used.

The diaminodiphenyl sulfone content may be 1 to 40 mole%, 3 to 30 mole%, or 5 to 25 mole% relative to 100 mole% of the total diamine.

(Preparation of polyimide)

The polyamic acid as a polyimide precursor can be obtained by the reaction of an acid dianhydride with a diamine, and the polyimide can be obtained by the dehydrative cyclization (imidization) of the polyamic acid. The composition of the polyimide, i.e., the kinds and ratios of the acid dianhydride and the diamine, is adjusted as described above, so that the polyimide has transparency and solubility in an organic solvent, and exhibits compatibility with an acrylic resin.

The method for producing the polyamic acid is not particularly limited, and various known methods can be applied. For example, a polyamic acid solution can be obtained by dissolving an acid dianhydride and a diamine in an organic solvent in approximately equal molar amounts (molar ratio of 95:100 to 105:100) and stirring the solution. The concentration of the polyamic acid solution is usually 5 to 35% by weight, preferably 10 to 30% by weight. If the concentration is in this range, the polyamic acid obtained by polymerization has an appropriate molecular weight, and the polyamic acid solution has an appropriate viscosity.

In the polymerization of the polyamic acid, a method of adding an acid dianhydride to a diamine is preferable in order to inhibit the ring opening of the acid dianhydride. When adding a plurality of diamines or a plurality of acid dianhydrides, the diamines or the acid dianhydrides may be added at one time or may be added in a plurality of times. By adjusting the order of addition of the monomers, the physical properties of the polyimide can be controlled.

The organic solvent used for polymerization of the polyamic acid is not particularly limited as long as it does not react with the diamine and the acid dianhydride and dissolves the polyamic acid. The organic solvents include: urea solvents such as methyl urea and N, N-dimethylethyl urea; sulfoxide or sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethylsulfone; amide solvents such as N, N-dimethylacetamide (DMAc), N-Dimethylformamide (DMF), N' -diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ -butyrolactone, and hexamethylphosphoric triamide; halogenated alkyl solvents such as chloroform and methylene chloride; aromatic hydrocarbon solvents such as benzene and toluene; ether solvents such as tetrahydrofuran, 1, 3-dioxolane, 1, 4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. In general, these solvents may be used alone or in combination of 2 or more kinds as appropriate. From the viewpoints of solubility of polyamic acid and polymerization reactivity, DMAc, DMF, NMP and the like are preferably used.

Polyimide can be obtained by dehydrative cyclization of polyamic acid. As a method for producing polyimide from a polyamic acid solution, there is a method in which a dehydrating agent, an imidization catalyst, or the like is added to a polyamic acid solution, and imidization is performed in the solution. The polyamic acid solution may be heated to promote the imidization. By mixing a solution containing polyimide produced by imidization of polyamic acid with a poor solvent, polyimide resin is precipitated as a solid. By separating the polyimide resin as a solid, impurities, residual dehydrating agents, imidization catalysts, and the like generated during the synthesis of the polyamic acid can be removed by washing with a poor solvent, and coloring of the polyimide, an increase in yellowness, and the like can be prevented. In addition, when a solution for producing a film is prepared by separating a polyimide resin as a solid, a solvent suitable for film formation such as a low boiling point solvent can be used.

The molecular weight of the polyimide (weight average molecular weight in terms of polyethylene oxide as measured by Gel Permeation Chromatography (GPC)) is preferably 10,000 ～ 300,000, more preferably 20,000 ～ 250,000, and further preferably 40,000 ～ 200,000. When the molecular weight is too small, the strength of the film is sometimes insufficient. When the molecular weight is too large, compatibility with the acrylic resin is sometimes poor.

The polyimide resin is preferably soluble in a non-amide solvent such as a ketone solvent or a halogenated alkyl solvent. The polyimide resin exhibiting solubility in a solvent means that the polyimide resin is dissolved at a concentration of 5% by weight or more. In one embodiment, the polyimide resin exhibits solubility in methylene chloride. Since methylene chloride has a low boiling point, it is easy to remove the residual solvent when producing a thin film, and thus, it is expected to improve the productivity of the thin film by using a polyimide resin which is soluble in methylene chloride.

Polyimide is preferably low in reactivity from the viewpoints of thermal stability and light stability of the resin composition and the film. The acid value of the polyimide is preferably 0.4mmol/g or less, more preferably 0.3mmol/g or less, and still more preferably 0.2mmol/g or less. The acid value of the polyimide may be 0.1mmol/g or less, 0.05mmol/g or less, or 0.03mmol/g or less. From the viewpoint of making the acid value smaller, polyimide is preferred to have a higher imidization rate. By making the acid value smaller, the stability of the polyimide tends to be improved, and the compatibility with the acrylic resin tends to be improved.

< Acrylic resin >

The acrylic resin may be: poly (meth) acrylates such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, methyl methacrylate- (meth) acrylic acid ester copolymers, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymers, methyl (meth) acrylate-styrene copolymers, and the like. The acrylic resin may be modified to incorporate a glutarimide structural unit or a lactone ring structural unit. The stereoregularity of the polymer is not particularly limited, and may be any of isotactic, syndiotactic and atactic.

From the viewpoints of transparency and compatibility with polyimide, and mechanical strength of molded articles such as films, the acrylic resin preferably contains methyl methacrylate as a main structural unit. The amount of methyl methacrylate in the acrylic resin is preferably 60 wt% or more, but may be 70 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, or 95 wt% or more, based on the total amount of the monomer components. The acrylic resin may be a homopolymer of methyl methacrylate.

As described above, the acrylic resin may have a glutarimide structure or a lactone ring structure introduced therein. Such a modified polymer is preferably one in which a glutarimide structure or a lactone ring structure is introduced into an acrylic polymer having a methyl methacrylate content within the above range. That is, in the acrylic resin modified by introducing the glutarimide structure or the lactone ring structure, the total amount of the methyl methacrylate and the modified structure of the methyl methacrylate is preferably 60% by weight or more, but may be 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The modified polymer may have a glutarimide structure or a lactone ring structure introduced into a homopolymer of methyl methacrylate.

By introducing a glutarimide structure or a lactone ring structure into an acrylic polymer such as methyl methacrylate, the glass transition temperature of the acrylic resin tends to be increased. In addition, since the glutarimide modified acrylic resin contains an imide structure, compatibility with polyimide may be improved.

The acrylic resin having a glutarimide structure is obtained by, for example, heating and melting a polymethyl methacrylate resin and treating the resin with an imidizing agent as described in JP-A2010-261025. When the acrylic polymer has a glutarimide structure, the glutarimide content may be 3 wt% or more, 5 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, or 50 wt% or more.

The glutarimide content was calculated as follows: the introduction rate (imidization rate) of the glutarimide structure was determined from ¹ H-NMR spectrum of the acrylic resin, and the imidization rate was converted into weight. For example, in methyl methacrylate having a glutarimide structure introduced therein, the imidization ratio im=b/(a+b) is obtained from the area a of the peak (in the vicinity of 3.5 to 3.8 ppm) of the O-CH ₃ proton derived from methyl methacrylate and the area B of the peak (in the vicinity of 3.0 to 3.3 ppm) of the N-CH ₃ proton derived from glutarimide.

The glass transition temperature of the acrylic resin is preferably 90℃or higher, more preferably 100℃or higher, still more preferably 110℃or higher, and may be 115℃or higher or 120℃or higher, from the viewpoint of heat resistance of the film.

From the viewpoints of solubility in an organic solvent, compatibility with the polyimide, and film strength, the weight average molecular weight (in terms of polystyrene) of the acrylic resin is preferably 5,000 ～ 500,000, more preferably 10,000 ～ 300,000, and further preferably 15,000 ～ 200,000.

From the viewpoints of thermal stability and photostability of the resin composition and the film, the acrylic resin preferably has a small content of reactive functional groups such as an ethylenically unsaturated group and a carboxyl group. The iodine value of the acrylic resin is preferably 10.16g/100g (0.4 mmol/g) or less, more preferably 7.62g/100g (0.3 mmol/g) or less, and still more preferably 5.08g/100g (0.2 mmol/g) or less. The iodine value of the acrylic resin may be 2.54g/100g (0.1 mmol/g) or less or 1.27g/100g (0.05 mmol/g) or less. The acid value of the acrylic resin is preferably 0.4mmol/g or less, more preferably 0.3mmol/g or less, and still more preferably 0.2mmol/g or less. The acid value of the acrylic resin may be 0.1mmol/g or less, 0.05mmol/g or less, or 0.03mmol/g or less. By making the acid value smaller, the stability of the acrylic resin tends to be improved, and the compatibility with polyimide tends to be improved.

< Preparation of resin composition >

The polyimide resin is mixed with an acrylic resin to prepare a resin composition. The polyimide resin and the acrylic resin may exhibit compatibility at an arbitrary ratio, and thus the ratio of the polyimide resin and the acrylic resin in the resin composition is not particularly limited. The mixing ratio (weight ratio) of the polyimide resin to the acrylic resin may be 98:2 to 2:98, 95:5 to 10:90, or 90:10 to 15:85. The higher the ratio of the polyimide resin, the higher the elastic modulus and pencil hardness of the film, and the more excellent the mechanical strength tends to be. The higher the ratio of the acrylic resin, the less the coloring of the film and the higher the transparency tend to be. In order to sufficiently exhibit the transparency-improving effect by mixing the polyimide resin and the acrylic resin, the ratio of the acrylic resin to the total of the polyimide resin and the acrylic resin is preferably 10% by weight or more, but may be 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 35% by weight or more, 40% by weight or more, 45% by weight or more, 50% by weight or more, 60% by weight or 70% by weight or more.

Polyimide is a polymer having a specific molecular structure, generally has low solubility in an organic solvent, and does not exhibit compatibility with other polymers. In this embodiment, the polyimide contains a fluoroalkyl-substituted benzidine as a diamine component and also contains an aromatic acid dianhydride other than fluorine as an acid dianhydride component, whereby the polyimide resin exhibits high solubility in an organic solvent and compatibility with an acrylic resin, and further exhibits excellent mechanical strength.

The resin composition comprising the polyimide resin and the acrylic resin preferably has a single glass transition temperature in Differential Scanning Calorimetry (DSC) and/or dynamic viscoelasticity (DMA). When the resin composition has a single glass transition temperature, it can be considered that the polyimide resin is fully compatible with the acrylic resin. The film comprising the polyimide resin and the acrylic resin also preferably has a single glass transition temperature.

The resin composition may be a mixed solution containing a polyimide resin and an acrylic resin. The method for mixing the resin is not particularly limited, and may be carried out in a solid state or in a liquid state to prepare a mixed solution. The polyimide resin solution and the acrylic resin solution may be separately prepared, and the two may be mixed to prepare a mixed solution of the polyimide resin and the acrylic resin.

The solvent of the solution containing the polyimide resin and the acrylic resin is not particularly limited as long as it is a solvent that exhibits solubility to both the polyimide resin and the acrylic resin. Examples of the solvent include: amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether solvents such as tetrahydrofuran and 1, 4-dioxane; ketone solvents such as acetone, methyl ethyl ketone, methyl acetone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; halogenated alkyl solvents such as chloroform, 1, 2-dichloroethane, 1, 2-tetrachloroethane, chlorobenzene, dichlorobenzene, and methylene chloride.

From the viewpoints of the solubility of the polyimide resin and the compatibility of the polyimide resin with the acrylic resin in solution, an amide-based solvent is preferable. On the other hand, from the viewpoint of solvent removability in producing molded articles such as films, a low-boiling non-amide solvent is preferable, and a ketone solvent and a halogenated alkyl solvent are preferable from the viewpoint of excellent solubility in both polyimide resin and acrylic resin, low boiling point, and easy removal of residual solvents in producing films. The resin composition has high compatibility between the polyimide resin and the acrylic resin, and thus can exhibit compatibility even in a low-boiling non-amide solvent such as a ketone solvent and a halogenated alkyl solvent.

In particular, when polyimide contains a fluorine-free aromatic tetracarboxylic dianhydride in which 2 acid anhydride groups are bonded to 1 aromatic ring, such as PMDA or MPDA, as an acid dianhydride component, compatibility with an acrylic resin tends to be excellent in a low-boiling non-amide solvent. The polyimide in the resin composition may have PMDA and/or MPDA as the acid dianhydride component. The total amount of PMDA and MPDA may be 5 to 65 wt%, 10 to 60 wt%, 15 to 55 wt%, or 20 to 50 wt% relative to the total amount of the acid dianhydride component of the polyimide.

As described above, the polyimide in the resin composition may contain PMDA and BPADA as fluorine-free aromatic tetracarboxylic dianhydride components. The total amount of PMDA and BPADA relative to the total amount of acid dianhydride component of the polyimide may be 30 to 70 wt%, 40 to 65 wt% or 45 to 60 wt%. The amount of BPADA may be 5 to 50 mol%, 10 to 40 mol%, 15 to 35 mol%, or 20 to 30 mol% with respect to the total amount of the acid dianhydride component of the polyimide.

For the purpose of improving the processability of the film, imparting various functions, and the like, an organic or inorganic low-molecular compound, a high-molecular compound (for example, an epoxy resin), and the like may be blended in the resin composition (solution). The resin composition may contain flame retardants, ultraviolet absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, microparticles, sensitizers, and the like. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, and inorganic fine particles such as colloidal silica, carbon and layered silicate, and may have a porous or hollow structure. The fiber reinforcement includes carbon fiber, glass fiber, aromatic polyamide fiber, and the like.

[ Molded article and film ]

The above composition can be used to form various shaped bodies. The molding method includes: injection molding, transfer molding, compression molding, blow molding, inflation molding, calender molding, melt extrusion molding, and other melt processes. The resin composition containing the polyimide resin and the acrylic resin tends to have a lower melt viscosity than polyimide alone, and is excellent in moldability such as injection molding, transfer molding, compression molding, and melt extrusion molding.

In addition, the solution of the resin composition containing the polyimide resin and the acrylic resin tends to have a lower solution viscosity than a single solution of the polyimide resin having the same solid content concentration. Therefore, the solution is excellent in handling properties such as conveyance and the like, and the coatability is high, which is advantageous in reducing thickness unevenness of the film.

In one embodiment, the shaped body is a film. The method for forming the film may be either a melt method or a solution method, and from the viewpoint of producing a film excellent in transparency and uniformity, the solution method is preferable. In the solution method, a film can be obtained by applying the solution containing the polyimide resin and the acrylic resin to a support and drying and removing the solvent.

As a method of applying the resin solution to the support, a known method using a bar coater or comma coater or the like can be applied. As the support, a glass substrate, a metal substrate such as SUS, a metal roller, a metal belt, a plastic film, or the like can be used. From the viewpoint of improving productivity, it is preferable to manufacture a film by roll-to-roll using a metal roll, an endless support such as a metal belt, or a long plastic film as a support. When a plastic film is used as the support, a material which is insoluble in a solvent to be doped for film formation can be appropriately selected.

The solvent is preferably heated when drying. The heating temperature is not particularly limited as long as the solvent is removable and the resulting film is inhibited from being colored, and the temperature is appropriately set at about room temperature to 250 ℃, preferably 50 to 220 ℃. The heating temperature may be raised stepwise. In order to improve the solvent removal efficiency, the resin film may be peeled off from the support and dried after a certain degree of drying. In order to facilitate the removal of the solvent, heating may be performed under reduced pressure.

Acrylic films sometimes have low toughness, but by using a compatible system of polyimide resins and acrylic resins, the strength of the film may be improved.

The thickness of the film is not particularly limited and may be appropriately set according to the application. The thickness of the film is, for example, 5 to 300. Mu.m. From the viewpoint of producing a film having both self-supporting property and flexibility and high transparency, the thickness of the film is preferably 20 μm to 100 μm, or may be 30 μm to 90 μm, 40 μm to 85 μm, or 50 μm to 80 μm. The thickness of the film used as a cover film for a display is preferably 50 μm or more.

The haze of the film is preferably 10% or less, more preferably 5% or less, further preferably 4% or less, and may be 3.5% or less, 3% or less, 2% or less, or 1% or less. The lower the haze of the film, the more preferred. As described above, since the polyimide resin and the acrylic resin exhibit compatibility, a film having low haze and high transparency can be obtained. The resin composition containing the polyimide resin and the acrylic resin preferably has a haze of 10% or less when formed into a film having a thickness of 50. Mu.m.

The light transmittance of the film at a wavelength of 400nm is preferably 45% or more, more preferably 50% or more, still more preferably 55% or more, and may be 60% or more, 65% or more, or 70% or more. The Yellowness (YI) of the film is preferably 3.0 or less, more preferably 2.5 or less, and may be 2.0 or less, 1.5 or less, or 1.0 or less. As described above, by mixing the polyimide resin with the acrylic resin, a film having less coloration, higher light transmittance at 400nm, and smaller YI can be obtained as compared with the case of using the polyimide resin alone.

From the viewpoint of strength, the tensile elastic modulus of the film is preferably 3.0GPa or more, more preferably 3.3GPa or more, still more preferably 3.4GPa or more, and may be 3.5GPa or more, 3.6GPa or more, 3.7GPa or more, 3.8GPa or more, 3.9GPa or more, or 4.0GPa or more. The pencil hardness of the film is preferably F or more, but may be H or more or 2H or more. In a compatible system of a polyimide resin and an acrylic resin, pencil hardness is not easily lowered even if the ratio of the acrylic resin is increased. Therefore, a film having excellent transparency, which is less colored without significantly deteriorating excellent mechanical strength peculiar to polyimide, can be provided.

Films formed from resin compositions comprising polyimide resins and acrylic resins are suitable for use as display materials because of their low coloration and high transparency. In particular, a film having high mechanical strength can be applied to surface members such as a cover window of a display. In practical application, the film of the invention can be provided with an antistatic layer, an easy-to-adhere layer, a hard coating layer, an anti-reflection layer and the like on the surface.

Examples

Hereinafter, embodiments of the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

[ Production example of polyimide resin ]

Dimethylformamide was put into a separable flask, and stirred under a nitrogen atmosphere. Diamine and acid dianhydride were added thereto in the ratios (mol%) shown in tables 1 and 2, and the mixture was stirred under a nitrogen atmosphere for 5 to 10 hours to react, thereby obtaining a polyamic acid solution having a solid content concentration of 18% by weight.

6.0G of pyridine was added to 100g of the polyamic acid solution as an imidization catalyst, and after complete dispersion, 8g of acetic anhydride was added thereto, and the mixture was stirred at 90℃for 3 hours. After cooling to room temperature, 100g of 2-propanol (hereinafter referred to as IPA) was charged at a rate of 2 to 3 drops/sec while stirring the solution, and the polyimide resin was precipitated. Further, 150g of IPA was added thereto, and after stirring for about 30 minutes, suction filtration was performed using a Tung mountain funnel (kiriyama funnel). After the obtained solid was washed with IPA, it was dried in a vacuum oven set to 120 ℃ for 12 hours to obtain a polyimide resin.

[ Film production example ]

Example 1 ]

Polyimide (PI) having a composition of 6 FDA/PMDA/tfmb=70/30/100 obtained in the above production example, and a commercially available polymethyl methacrylate resin (commercially available from kohl corporation, "PARAPET HM1000", glass transition temperature: 120 ℃, acid value: 0.0mmol/g, hereinafter referred to as "acrylic resin 1") were mixed at a ratio of 50: 50% by weight was dissolved in Methyl Ethyl Ketone (MEK) to prepare a solution having a resin component of 11% by weight. The solution was applied to an alkali-free glass plate, and dried under an atmosphere at 60℃for 15 minutes, at 90℃for 15 minutes, at 120℃for 15 minutes, at 150℃for 15 minutes, at 180℃for 15 minutes, and at 200℃for 15 minutes, to prepare a film having a thickness of about 50. Mu.m.

< Examples 2 to 14, comparative examples 1 to 11>

Films were produced under the same conditions as described above except that the polyimide compositions were changed as shown in tables 1 and 2, and methylene chloride (DCM) or N, N-Dimethylformamide (DMF) was used as a solvent instead of Methyl Ethyl Ketone (MEK) as shown in tables 1 and 2.

< Examples 15 to 20>

Films were produced under the same conditions as described above, except that the following acrylic resins 2 to 4 were used instead of the acrylic resin 1.

Acrylic resin 2: methyl methacrylate/methyl acrylate (monomer ratio 87/13) copolymer (Kagaku Kogyo "parapet G-1000", glass transition temperature 109 ℃ C., acid value 0.0 mmol/g)

Acrylic resin 3: acrylic resin having glutarimide ring (glutarimide content 4% by weight, glass transition temperature 125 ℃ C., acid value 0.4 mmol/g) produced in accordance with "acrylic resin production example" of Japanese patent application laid-open No. 2018-70710

Acrylic resin 4: acrylic resin having glutarimide ring (glutarimide content 70% by weight, glass transition temperature 146 ℃ C., acid value 0.1 mmol/g) produced in accordance with "acrylic resin production example" of Japanese patent application laid-open No. 2018-70710

< Reference examples 1 to 4>

A MEK solution of a polyimide resin was prepared in referential example 1, a DMF solution of a polyimide resin was prepared in referential example 3, and a film having a thickness of about 50 μm was produced under the same conditions as described above. In reference examples 2 and 4, a film having a thickness of about 50 μm was produced under the same conditions as described above except that the methylene chloride solutions of the acrylic resins 1 and 3 were prepared and the heating conditions during drying were changed to 30 minutes at 60 ℃,30 minutes at 80 ℃,30 minutes at 100 ℃, and 30 minutes at 110 ℃.

[ Evaluation of compatibility ]

A film having a thickness of about 50 μm was produced in the same manner as in the above examples by dissolving the mixture of the polyimide resin and the acrylic resin shown in tables 1 and 2 in DMF and DCM so that the resin component was 11% by weight, and the haze of the film was measured. The haze of 20% or less was judged to be compatible (o), and the haze of more than 20% was judged to be incompatible (x). It was determined that there was no compatibility between the case where the clear cloudiness of the solution was visually confirmed and the case where the solution was separated into 2 phases, without producing a film (x).

[ Evaluation of film ]

< Haze and Total light transmittance >

The film was cut into 3cm squares, and haze and total light transmittance (TT) were measured in accordance with JIS K7136 and JIS K7361-1 using Suga Test Instruments Co., ltd. Haze meter "HZ-V3". The following measurement of yellowness, tensile elastic modulus and pencil hardness was not performed for haze exceeding 20%.

< Light transmittance at 400nm >

The transmittance of the film at 300 to 800nm was measured by using an ultraviolet-visible spectrophotometer "V-770" manufactured by Japanese spectroscopic company, and the transmittance at 400nm was read.

< Yellow color >

The film was cut into 3cm squares, and the Yellowness (YI) was measured according to JIS K7373 using Suga Test Instruments Co., ltd. Spectrocolorimeter "SC-P".

< Tensile elastic modulus >

The film was cut into short strips having a width of 10mm, left standing at 23℃and 55% RH for 1 day to adjust the humidity, and then the tensile modulus was measured using "AUTOGRAPH AGS-X" manufactured by Shimadzu corporation under the following conditions.

Distance between clamps: 100mm of

Stretching speed: 20.0mm/min

Measuring temperature: 23 DEG C

< Pencil hardness >

The pencil hardness of the film was measured in accordance with JIS K5600-5-4 "pencil scratch test".

< Bending resistance >

The film was cut into a short strip of 20mm×100mm, and the film was bent 180 ° at the center in the longitudinal direction, and the film which was not broken was marked "o", and the film which was broken was marked "x".

[ Evaluation results ]

The evaluation results of the resin composition (polyimide composition, acrylic resin type, and blend ratio) and the film are shown in tables 1 and 2.

In tables 1 and 2, the compounds are described by the following abbreviations.

< Acid dianhydride >

6FDA 4,4' - (hexafluoroisopropylidene) diphthalic anhydride

PMDA pyromellitic dianhydride

MPDA, phenyltrimellitic acid dianhydride

BPDA 3,3', 4' -Biphenyltetracarboxylic dianhydride

BPADA 4,4'- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride

BTDA 3,3', 4' -benzophenone tetracarboxylic dianhydride

ODPA 4,4' -Oxyphthalic anhydride

BPAF 9, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride

TAHQ p-phenylene bis (trimellitic anhydride)

TAHMBP bis (1, 3-dioxo-1, 3-dihydroisobenzofuran-5-carboxylic acid) -2,2', 3',5 '-hexamethylbiphenyl-4, 4' -diyl ester

< Diamine >

TFMB 2,2' -bis (trifluoromethyl) benzidine

DDS 3,3' -diaminodiphenyl sulfone

ODA 3,4' -diaminodiphenyl ether

M-PDA m-phenylenediamine

BAPP 2,2' -bis [4- (4-aminophenoxy) phenyl ] propane

HFBAPP 2,2' -bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane

TABLE 1

TABLE 2

The polyimide film of reference example 1, which was produced using only a polyimide resin, had a high tensile elastic modulus and excellent mechanical properties, but YI exceeding 2 was insufficient in transparency. The acrylic film of reference example 2 produced using only acrylic resin 1 has a low tensile elastic modulus, a pencil hardness of HB, and insufficient mechanical strength. In addition, the acrylic film of reference example 2 also had insufficient bending resistance.

In example 1, a resin composition in which the same polyimide resin and acrylic resin 1 as in reference example 1 were mixed was used, and the total light transmittance of the film and the light transmittance at a wavelength of 400nm were higher, YI was smaller, coloration was less, and transparency was improved, as compared with the polyimide film of reference example 1. The film of example 1 had a higher mechanical strength than the acrylic film of reference example 2, and had a tensile elastic modulus and pencil hardness equivalent to those of the polyimide film of reference example 1.

In examples 2 to 14 using a polyimide resin different from that of example 1, the haze of the film was small, YI was small, and the mechanical strength was improved as compared with the acrylic film of reference example 2, similarly to example 1. The films of examples 15 and 16, which correspond to the acrylic resin of example 14, also have excellent mechanical strength and transparency, and example 17, which corresponds to the ratio of the polyimide resin to the acrylic resin of example 16, also has excellent mechanical strength and transparency. The films of examples 18 to 20 also have excellent mechanical strength and transparency by using the acrylic resin 4 having a higher glutarimylation ratio than the acrylic resin 3.

As is clear from the comparison of the polyimide film of reference example 3 and the acrylic film of reference example 4 with the film of example 17, the resin films in which the polyimide resin and the acrylic resin are mixed are superior in mechanical strength to those in the case of the acrylic resin alone, and are improved in transparency to those in the case of the polyimide alone, as in the comparison of reference examples 1 and 2 with example 1.

From the comparison of reference example 3, example 17, example 16, and reference example 4, it is seen that the YI decreases linearly and the light transmittance increases linearly as the ratio of the acrylic resin increases. That is, it is known that the transparency of the film is improved by increasing the ratio of the acrylic resin. On the other hand, regarding the mechanical strength, it was found that the tensile elastic modulus tended to decrease as the ratio of the acrylic resin increased, and the tensile elastic modulus was the same for reference example 3 containing no acrylic resin and example 17 where the ratio of the acrylic resin was 30%. From these results, it is found that the transparency can be improved with little decrease in mechanical strength of the film when the ratio of the acrylic resin is low.

The film of comparative example 1, which uses a polyimide resin containing only fluorine-containing aromatic tetracarboxylic dianhydride, i.e., 6FDA as the tetracarboxylic dianhydride, and containing no fluorine-free aromatic tetracarboxylic dianhydride, has excellent transparency, but has a tensile elastic modulus of 3.3GPa and lower mechanical strength than the film of example 1 and the like. In comparative example 2 in which a film was produced by dissolving the same resin composition as in comparative example 1 in methylene chloride, the polyimide resin and the acrylic resin did not show compatibility, and the haze was remarkably increased.

The compositions of comparative examples 4 and 5, in which the diamine type of the polyimide of comparative example 1 was changed, also showed no compatibility between the polyimide resin and the acrylic resin in DMF. The same applies to comparative examples 10 and 11.

Comparative examples 3, 6 to 8, in which the diamine type of the polyimide of comparative example 1 was changed, were lower in mechanical strength than comparative example 1. In addition, the films of comparative examples 6 and 8 have a large YI and insufficient transparency. The film of comparative example 9, in which the ratio of fluorine-containing aromatic tetracarboxylic dianhydride (6 FDA) was small, had lower mechanical strength than examples 10 and 11.

The films of examples 4 to 6 have the tensile elastic modulus equivalent to that of comparative example 1, but have the following advantages: polyimide resins have high compatibility with acrylic resins, and exhibit excellent compatibility with non-amide solvents such as methylene chloride, so that films having high transparency can be obtained. The compositions of examples 2, 3, 18, 19 exhibited compatibility in methylene chloride and had excellent mechanical strength. The composition of example 1 showed no compatibility in methylene chloride, but compatibility in methyl ethyl ketone as a non-amide solvent.

In examples 1 to 6 and examples 18 and 19, it is considered that the fluorine-free tetracarboxylic dianhydride in which 2 acid anhydride groups are bonded to 1 benzene ring, i.e., PMDA and MPDA, contributes to improving the compatibility of the polyimide resin with the acrylic resin. In examples 2 to 4, 18 and 19, BPADA was also considered to contribute to improvement of compatibility.

From the above results, it was found that a polyimide containing a specific amount of fluorine-containing aromatic tetracarboxylic dianhydride and fluorine-free aromatic tetracarboxylic dianhydride as tetracarboxylic dianhydride components and containing fluoroalkyl-substituted benzidine as diamine component exhibited compatibility with an acrylic resin, and a resin composition containing these components was used to obtain a film having high transparency and excellent mechanical strength.

Claims (10)

1. A resin composition comprising a polyimide and an acrylic resin,

The polyimide contains fluorine-containing aromatic tetracarboxylic dianhydride and fluorine-free aromatic tetracarboxylic dianhydride as tetracarboxylic dianhydride components, and fluoroalkyl-substituted benzidine as diamine component,

The amount of fluorine-containing aromatic tetracarboxylic dianhydride is 30 to 90 mol% relative to the total amount of tetracarboxylic dianhydride components of the polyimide, the amount of fluorine-free aromatic tetracarboxylic dianhydride is 10 to 70 mol%,

The amount of fluoroalkyl-substituted benzidine is 25 mol% or more based on the total amount of diamine components of the polyimide.

2. The resin composition according to claim 1, wherein the fluorine-free tetracarboxylic dianhydride comprises a compound selected from the group consisting of pyromellitic dianhydride, trimellitic dianhydride, 3', 4' -biphenyl tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride, 3', more than 1 of 4,4' -benzophenone tetracarboxylic dianhydride, 4' - (4, 4' -isopropylidenediphenoxy) diphthalic anhydride, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, and bis (trimellitic anhydride) ester.

3. The resin composition according to claim 1 or 2, wherein the fluorine-containing aromatic tetracarboxylic dianhydride is 4,4' - (hexafluoroisopropylidene) diphthalic anhydride.

4. The resin composition according to claim 1 or 2, wherein the fluoroalkyl-substituted benzidine is 2,2' -bis (trifluoromethyl) benzidine.

5. The resin composition according to claim 1 or 2, wherein the total amount of methyl methacrylate and the modified structure of methyl methacrylate in the acrylic resin is 60 wt% or more based on the total amount of the monomer components.

6. The resin composition according to claim 1 or 2, wherein the glass transition temperature of the acrylic resin is 90 ℃ or higher.

7. The resin composition according to claim 1 or 2, comprising the polyimide and the acrylic resin in a weight ratio in the range of 98:2 to 2:98.

8. A molded article comprising the resin composition according to claim 1 or 2.

9. A film comprising the resin composition of claim 1 or 2.

10. The film according to claim 9, which has a thickness of 5 μm or more and 300 μm or less, a total light transmittance of 85% or more, a haze of 10% or less, a yellowness of 3.0 or less, a tensile elastic modulus of 3.0GPa or more, and a pencil hardness of F or more.