JP2023086071A - Resin composition and film - Google Patents

Abstract

To provide a transparent film that has high transparency and sufficient mechanical strength, and to provide a resin composition that is used for producing the same.SOLUTION: Provided is a resin composition, which is a resin composition containing polyimide and acrylic resin, and in which the polyimide has a structure derived from tetracarboxylic dianhydride and a structure derived from diamine and in which fluoroalkyl-substituted benzidine is included in the structure derived from diamine and pyromellitic acid dianhydride and/or mellophanic acid dianhydride is included in the structure derived from tetracarboxylic acid dianhydride, and that is soluble in amide-based solvent.SELECTED DRAWING: None

Description

The present invention relates to resin compositions and films.

BACKGROUND ART In display devices such as liquid crystal, organic EL, and electronic paper, and in electronic devices such as solar cells and touch panels, thinning, weight reduction, and flexibility are required. By replacing the glass material used in these devices with a film material, flexibility, thinness, and weight reduction can be achieved. A transparent polyimide film has been developed as a substitute material for glass and is used for display substrates, cover films, and the like.

A normal polyimide film is obtained by coating a polyamic acid solution, which is a polyimide precursor, on a support in the form of a film, and subjecting it to a high temperature treatment to remove the solvent and perform thermal imidization at the same time. However, the heating temperature for thermal imidization is high (for example, 300 ° C. or higher), and coloring (increase in yellowness) due to heating is likely to occur, making it difficult to apply to applications requiring high transparency such as cover films for displays. Have difficulty.

As a method for producing a highly transparent polyimide film, a method using a polyimide resin that is soluble in an organic solvent and does not require high-temperature imidization after film formation has been proposed. For example, Patent Document 1 proposes a method for producing a polyimide containing a bis-trimmellitic anhydride as a tetracarboxylic dianhydride component, and the polyimide obtained by this method is dissolved in a low boiling point solvent such as dichloromethane. It is described as being soluble and having excellent transparency and mechanical strength.

WO2020/004236

Introducing a rigid structure into polyimide improves its mechanical strength, but it also causes a decrease in its solubility in organic solvents and transparency. It's not easy to have. In view of such problems, an object of the present invention is to provide a transparent film that is highly transparent, can reduce coloring, and has sufficient mechanical strength, and a resin composition that is used for producing the transparent film.

As a result of intensive studies, the present inventors have found that the above problems can be solved by using the following resin composition. The present invention has the following configurations.

1). A resin composition containing polyimide and acrylic resin,
The polyimide has a structure derived from tetracarboxylic dianhydride and a structure derived from diamine,
Including a fluoroalkyl-substituted benzidine in the structure derived from the diamine,
Including pyromellitic dianhydride and / or merophanic dianhydride in the structure derived from the tetracarboxylic dianhydride,
A resin composition that is soluble in an amide solvent.

2). The structure derived from the tetracarboxylic dianhydride further includes 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride, bis(trimellitic anhydride) ester, 9,9-bis(3, 4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 5,5'-dimethylmethylenebis(phthalic anhydride), 3, 3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3′,4,4′-tetracarboxylic dianhydride, 4 ,4'-(hexafluoroisopropylidene)diphthalic anhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride.

3). The resin composition according to 2), wherein the bis(trimellitic anhydride) ester is represented by the following general formula (1).
(However, X in general formula (1) is a divalent organic group selected from (A) to (K) below.)

4). The resin composition according to any one of 1) to 3), wherein the amount of pyromellitic dianhydride and/or melophanic dianhydride is 10 mol% to 50 mol%.

5). The resin composition according to any one of 1) to 4), wherein the fluoroalkyl-substituted benzidine is 2,2'-bis(trifluoromethyl)benzidine.

6). The resin composition according to any one of 1) to 5), wherein the amount of fluoroalkyl-substituted benzidine in the diamine-derived structure of the polyimide is 50 mol% or more.

7). The resin composition according to any one of 1) to 6), wherein the diamine-derived structure is a condensation structure of 2,2'-bis(trifluoromethyl)benzidine and dicarboxylic acid.

8). 7), wherein the dicarboxylic acid is one or more selected from terephthalic acid, isophthalic acid and biphenyl-4,4'-dicarboxylic acid.

9). The resin composition according to 7) or 8), wherein the condensed structure of 2,2'-bis(trifluoromethyl)benzidine and dicarboxylic acid accounts for 10 to 100 mol% of the diamine-derived structure.

10). pyromellitic dianhydride and/or merophanic dianhydride and 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride in the tetracarboxylic dianhydride-derived structure of the polyimide; bis(trimellitic anhydride) ester, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride, 5,5′-dimethylmethylenebis(phthalic anhydride), 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3 ,3′,4,4′-tetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride. The resin composition according to any one of 1) to 9), wherein the total of one or more types of

11). The resin composition according to any one of 1) to 10), wherein the acrylic resin contains 60% by weight or more of methyl methacrylate with respect to the total amount of monomer components.

12). The resin composition according to any one of 1) to 11), wherein the acrylic resin has a glass transition temperature of 80°C or higher.

13). The resin composition according to any one of 1) to 12), which contains the polyimide and the acrylic resin in a weight ratio ranging from 98:2 to 2:98.

14). A film comprising the resin composition according to any one of 1) to 13).

15). The film according to 14), which has a thickness of 5 μm or more and 300 μm or less.

16). When the thickness is 50 μm, the total light transmittance is 85% or more, the haze is 10% or less, the yellowness is 5.0 or less, the tensile modulus is 3.5 GPa or more, and the pencil hardness is F or more. 14) or 15 ).

Since the polyimide resin and the acrylic resin contained in the resin composition show compatibility, a transparent film with a small haze can be obtained. In addition, since polyimide resin and acrylic resin show compatibility, it has high transparency and can reduce coloring without significantly reducing the excellent mechanical strength of polyimide, making it suitable for display cover films, etc. Film can be made.

[Resin composition]
One embodiment of the present invention is a compatible resin composition containing a polyimide resin and an acrylic resin, wherein the polyimide has a structure derived from a tetracarboxylic dianhydride and a structure derived from a diamine, A resin comprising a fluoroalkyl-substituted benzidine in a diamine-derived structure, a pyromellitic dianhydride and/or merophanic dianhydride in the tetracarboxylic dianhydride-derived structure, and being soluble in an amide solvent. composition. 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride as the structure derived from tetracarboxylic dianhydride, 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride, 5,5′-dimethylmethylenebis(phthalic acid anhydride), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid 2,3:6,7-dianhydride, 11 ,11-dimethyl-1H-difuro[3,4-b:3′,4′-i]xanthene-1,3,7,9(11H)-tetrone, terphenyltetracarboxylic dianhydride, 1,4 -bis(3,4-dicarboxyphenoxy)benzene dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2- dicarboxylic dianhydride, ethylene glycol bis(trimellitic anhydride), naphthalene-1,4,5,8-tetracarboxylic dianhydride, N,N'-(9H-fluorene-9-ylidene di-4, 1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], N,N'-[[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] bis(6-hydroxy-3,1-phenylene)]bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], 2,2-bis(4-hydroxyphenyl)propane dibenzoate-3 , 3′,4,4′-tetracarboxylic dianhydride.

Soluble in an amide solvent is selected from N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP) 5% by weight or more of the polyimide at 25° C. in the amide-based solvent.

Hereinafter, compounds are described by the following abbreviations.
6FDA (4,4'-(hexafluoroisopropylidene)diphthalic anhydride)
PMDA (pyromellitic dianhydride),
MPDA (melophane dianhydride),
BTDA (3,3′,4,4′-benzophenonetetracarboxylic dianhydride or 2,2′,3,3′-benzophenonetetracarboxylic dianhydride),
ODPA (4,4'-oxydiphthalic anhydride or 3,4'-oxydiphthalic anhydride),
DSDA (3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride),
BPADA (4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride),
6HDA (5,5′-dimethylmethylenebis(phthalic anhydride)),
BPAF (9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride),
NTDA (2,3,6,7-naphthalenetetracarboxylic acid 2,3:6,7-dianhydride),
6HCDA (11,11-dimethyl-1H-diflo[3,4-b:3′,4′-i]xanthene-1,3,7,9(11H)-tetrone),
TerPDA (terphenyltetracarboxylic dianhydride),
HQDEA (1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride),
TDA (4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride),
TMEG (ethylene glycol bis(trimellitic anhydride)),
NADA (naphthalene-1,4,5,8-tetracarboxylic dianhydride),
FDA-ATA (N,N'-(9H-fluorene-9-ylidenedi-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide]),
6FAP-ATA(N,N'-[[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis(6-hydroxy-3,1-phenylene)]bis[1,3-dihydro- 1,3-dioxo-5-isobenzofurancarboxamide]),
ESDA (2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride)

ポリイミドとは、一般式（２）のような構造を有するものをいい、ジアミンとテトラカルボン酸二無水物（以下、「酸二無水物」と記載する場合がある）との付加重合により得られるポリアミド酸の脱水環化や、ジイソシアネートと酸二無水物との脱炭酸による縮合などによって合成することができる。但し、一般式（２）中のＸは４価の有機基、Ｙは２価の有機基を表す。 <Polyimide>

Polyimide refers to those having a structure such as the general formula (2), obtained by addition polymerization of diamine and tetracarboxylic dianhydride (hereinafter sometimes referred to as "acid dianhydride") It can be synthesized by cyclodehydration of polyamic acid, condensation by decarboxylation of diisocyanate and acid dianhydride, and the like. However, X in general formula (2) represents a tetravalent organic group and Y represents a divalent organic group.

本件発明では、ポリイミドを合成する出発原料が、酸二無水物でない場合でも、イミド一般式（３）中の直線で囲まれた部分に相当する構造を有すれば、酸二無水物由来構造とする。また、ポリイミドを合成する出発原料が、ジアミンでない場合でも、一般式（３）中の点線で囲まれた部分に相当する構造を有すれば、ジアミン由来構造と表現する。但し、一般式（３）中のＸは４価の有機基、Ｙは２価の有機基を表す。

In the present invention, even if the starting material for synthesizing the polyimide is not an acid dianhydride, if it has a structure corresponding to the portion surrounded by straight lines in the imide general formula (3), it is an acid dianhydride-derived structure. do. Even if the starting material for polyimide synthesis is not diamine, if it has a structure corresponding to the portion surrounded by the dotted line in general formula (3), it is expressed as a diamine-derived structure. However, X in general formula (3) represents a tetravalent organic group, and Y represents a divalent organic group.

(diamine)
The polyimide used in this embodiment contains a fluoroalkyl-substituted benzidine as a diamine-derived structure. Having a fluoroalkyl-substituted benzidine in the diamine-derived structure tends to achieve both the solubility and transparency of the polyimide resin.

Examples of fluoroalkyl-substituted benzidines include 2-(trifluoromethyl)benzidine, 3-(trifluoromethyl)benzidine, 2,3-bis(trifluoromethyl)benzidine, 2,5-bis(trifluoromethyl)benzidine , 2,6-bis(trifluoromethyl)benzidine, 2,3,5-tris(trifluoromethyl)benzidine, 2,3,6-tris(trifluoromethyl)benzidine, 2,3,5,6-tetrakis (trifluoromethyl)benzidine, 2,2′-bis(trifluoromethyl)benzidine, 3,3′-bis(trifluoromethyl)benzidine, 2,3′-bis(trifluoromethyl)benzidine, 2,2′ ,3-tris(trifluoromethyl)benzidine, 2,3,3′-tris(trifluoromethyl)benzidine, 2,2′,5-tris(trifluoromethyl)benzidine, 2,2′,6-tris( trifluoromethyl)benzidine, 2,3′,5-tris(trifluoromethyl)benzidine, 2,3′,6,-tris(trifluoromethyl)benzidine, 2,2′,3,3′-tetrakis(tri fluoromethyl)benzidine, 2,2′,5,5′-tetrakis(trifluoromethyl)benzidine, 2,2′,6,6′-tetrakis(trifluoromethyl)benzidine and the like.

Among them, fluoroalkyl-substituted benzidine having a fluoroalkyl group at the 2-position of biphenyl is preferred, and 2,2'-bis(trifluoromethyl)benzidine (hereinafter referred to as "TFMB") is particularly preferred. By having fluoroalkyl groups at the 2- and 2′-positions of biphenyl, in addition to the reduction in π electron density due to the electron-withdrawing property of the fluoroalkyl groups, the steric hindrance of the fluoroalkyl groups results in the separation of two benzene rings of biphenyl. Since the interbonds are twisted and the planarity of the π-conjugation is lowered, the absorption edge wavelength is shifted to a shorter wavelength, and coloring of the polyimide can be reduced.

Even when the structure derived from diamine contains a condensed structure of fluoroalkyl-substituted benzidine and dicarboxylic acid, the structure derived from diamine contains fluoroalkyl-substituted benzidine.

（４）
General formula (4) can be exemplified as a preferable example of the diamine containing the condensed structure of the fluoroalkyl-substituted benzidine and dicarboxylic acid. provided that R ¹ and R ² in general formula (4) are independently halogen, methyl group, or trifluoromethyl group, m is an integer of 0 to 3, and either R ¹ or R ² m is not 0. R ³ is an unsubstituted benzene ring or biphenyl, or a benzene ring or biphenyl substituted with halogen, methyl group or trifluoromethyl group.

(4)

In general formula (4), the structure of a diamine obtained by condensing two fluoroalkyl-substituted benzidines and one dicarboxylic acid is exemplified. Even with a diamine in which four are condensed with three dicarboxylic acids, a diamine in which five fluoroalkyl-substituted benzidines and four dicarboxylic acids are condensed, the resulting polyimide tends to exhibit high elasticity and high transparency. It is preferable because

A structure corresponding to general formula (4) may also be introduced into a polyimide by a method of condensing a fluoroalkyl-substituted benzidine-terminated polyamic acid oligomer or a fluoroalkyl-substituted benzidine-terminated polyimide oligomer with a dicarboxylic acid or a dichloride of a dicarboxylic acid. can be done.

From the viewpoint of exhibiting transparency and high elasticity, the general formula (4) is preferably a condensation structure of 2,2'-bis(trifluoromethyl)benzidine and a dicarboxylic acid, and the dicarboxylic acid is terephthalic acid or Biphenyl-4,4'-dicarboxylic acid is more preferred because it exhibits a higher elastic modulus.

From the viewpoint of exhibiting solubility in a solvent, the dicarboxylic acid is preferably isophthalic acid.

The content of diamine containing a condensed structure of fluoroalkyl-substituted benzidine and dicarboxylic acid is preferably 10 to 100 mol%, more preferably 10 to 80 mol%, and even more preferably 10 to 50 mol% with respect to 100 mol% of the total diamine component. . A high content of diamine containing a condensation structure of fluoroalkyl-substituted benzidine and dicarboxylic acid tends to suppress coloration of the film and increase mechanical strength such as pencil hardness and elastic modulus. Although general formula (4) has two fluoroalkyl-substituted benzidines, when calculating the content of fluoroalkyl-substituted benzidines with respect to 100 mol % of the total amount of diamine components, it is calculated as one diamine.

The content of the fluoroalkyl-substituted benzidine relative to 100 mol% of the total amount of the diamine component is preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more, 45 mol% or more, 50 mol% or more, or 60 mol% or more. It may be mol% or more. A high content of the fluoroalkyl-substituted benzidine tends to suppress the coloring of the film and increase mechanical strength such as pencil hardness and elastic modulus. Although general formula (4) has two fluoroalkyl-substituted benzidines, when calculating the content of fluoroalkyl-substituted benzidines with respect to 100 mol % of the total amount of diamine components, it is calculated as one diamine.

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-fluorobenzidine, 3-fluorobenzidine, 2,3-difluorobenzidine, 2,5-difluorobenzidine, 2,6-difluorobenzidine, 2,3,5-trifluorobenzidine. fluorobenzidine, 2,3,6-trifluorobenzidine, 2,3,5,6-tetrafluorobenzidine, 2,2′-difluorobenzidine, 3,3′-difluorobenzidine, 2,3′-difluorobenzidine, 2 ,2′,3-trifluorobenzidine, 2,3,3′-trifluorobenzidine, 2,2′,5-trifluorobenzidine, 2,2′,6-trifluorobenzidine, 2,3′,5- trifluorobenzidine, 2,3′,6,-trifluorobenzidine, 2,2′,3,3′-tetrafluorobenzidine, 2,2′,5,5′-tetrafluorobenzidine, 2,2′,6 ,6'-tetrafluorobenzidine, 2,2',3,3',6,6'-hexafluorobenzidine, 2,2',3,3',5,5',6,6'-octafluorobenzidine , 2,4-diaminotoluene, 2,5-diaminotoluene, 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 sulfone, 3,4'-diaminodiphenyl sulfone, 4 ,4'-diaminodiphenylsulfone, 9,9-bis(4-aminophenyl)fluorene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'- Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di(3-aminophenyl)propane, 2,2-di(4-aminophenyl)propane, 2-(3- aminophenyl)-2-(4-aminophenyl)propane, 1,1-di(3-aminophenyl)-1-phenylethane, 1,1-di(4-aminophenyl)-1-phenylethane, 1- (3-aminophenyl)-1-(4-aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4 -bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene, 1,3-bis(4-aminobenzoyl)benzene, 1 , 4-bis(3-aminobenzoyl)benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis( 4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene , 2,6-bis(3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4′-bis(3-aminophenoxy)biphenyl, 4,4′-bis(4 -aminophenoxy)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, 2,2-bis[4-(4-aminophenoxy) Phenyl]propane, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,4-bis[4-(3 -aminophenoxy)benzoyl]benzene, 1,4-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-aminophenoxy)-α,α-dimethylbenzyl]benzene, 1, 4-bis[4-(4-aminophenoxy)-α,α-dimethylbenzyl]benzene, 4,4′-bis[4-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4′-bis[4- (4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4′-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, 4,4′-bis[4 -(4-aminophenoxy)phenoxy]diphenylsulfone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 3,3'-diamino -4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'- Spirobindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 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(amino methyl)ether, bis(2-aminoethyl)ether, bis(3-aminopropyl)ether, bis(2-aminomethoxy)ethyl]ether, bis[2-(2-aminoethoxy)ethyl]ether, bis[2 -(3-aminoprotoxy)ethyl]ether, 1,2-bis(aminomethoxy)ethane, 1,2-bis(2-aminoethoxy)ethane, 1,2-bis[2-(aminomethoxy)ethoxy] Ethane, 1,2-bis[2-(2-aminoethoxy)ethoxy]ethane, ethylene glycol bis(3-aminopropyl) ether, diethylene glycol bis(3-aminopropyl) ether, triethylene glycol bis(3-aminopropyl) ) ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9 -diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, trans-1,4 -diaminocyclohexane, 1,2-di(2-aminoethyl)cyclohexane, 1,3-di(2-aminoethyl)cyclohexane, 1,4-di(2-aminoethyl)cyclohexane, bis(4-aminocyclohe xyl)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, by using diaminodiphenylsulfone as the diamine in addition to the fluoroalkyl-substituted benzidine, the solubility in the solvent and the transparency of the polyimide resin may be improved. Among diaminodiphenylsulfones, 3,3'-diaminodiphenylsulfone (3,3'-DDS) and 4,4'-diaminodiphenylsulfone (4,4'-DDS) are preferred. 3,3'-DDS and 4,4'-DDS may be used in combination.

The content of diaminodiphenylsulfone relative to 100 mol % of the total amount of diamine may be 1 to 40 mol %, 3 to 30 mol %, or 5 to 25 mol %.

(Acid dianhydride)
The polyimide used in this embodiment contains pyromellitic dianhydride and/or merophanic dianhydride as a structure derived from tetracarboxylic dianhydride. Further structures derived from tetracarboxylic dianhydride include 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride, bis(trimellitic anhydride) ester, 9,9-bis(3,4 -dicarboxyphenyl)fluorene dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 5,5'-dimethylmethylenebis(phthalic anhydride), 3,3 ',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 4, It may contain one or more selected from 4′-(hexafluoroisopropylidene)diphthalic anhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride.
When the structure derived from tetracarboxylic dianhydride has pyromellitic dianhydride and/or merophanic dianhydride, compatibility with acrylic resin tends to be improved.

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

X in general formula (1) is a divalent organic group selected from the following (A) to (K).

R ¹ in formula (A) is a hydrogen atom, 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 1 to 4. The group represented by formula (A) is a group obtained by removing two hydroxyl groups from a hydroquinone derivative having a substituent on the benzene ring. Hydroquinones having a substituent on the benzene ring include tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone and the like.

R ² in formula (B) is a hydrogen atom, 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 0-4. The group represented by formula (B) is a group obtained by removing two hydroxyl groups from biphenol which may have a substituent on the benzene ring. Biphenol derivatives having a substituent on the benzene ring include 2,2′-dimethylbiphenyl-4,4′-diol, 3,3′-dimethylbiphenyl-4,4′-diol, 3,3′,5, 5'-tetramethylbiphenyl-4,4'-diol, 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diol and the like.

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

p in formula (E) is an integer of 1-10. The group represented by formula (E) is a straight-chain diol having 1 to 10 carbon atoms from which two hydroxyl groups have been removed. Examples of linear diols having 1 to 10 carbon atoms include ethylene glycol and 1,4-butanediol.

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

R ³ in formula (G) is a hydrogen atom, 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 0-4. The group represented by formula (G) is a group obtained by removing two hydroxyl groups from bisphenolfluorene which may have a substituent on the benzene ring having a phenolic hydroxyl group. Examples of the bisphenol fluorene derivative which may have a substituent on the benzene ring having a phenolic hydroxyl group include biscresol fluorene.

When X is a group represented by the general formula (B), from the viewpoint of the solubility of the polyimide resin, X is represented by the following formula (B1) 2,2',3,3',5, 5'-Hexamethylbiphenyl-4,4'-diyl is preferred.

An acid dianhydride in which X is a group represented by the formula (B1) in the general formula (1) has the following formula (5
Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2′,3,3′,5,5′-hexamethylbiphenyl-4,4′diyl represented by (abbreviation: TAHMBP).

The polyimide may contain a tetracarboxylic dianhydride other than the above tetracarboxylic dianhydride as a structure derived from the tetracarboxylic dianhydride. Examples of these tetracarboxylic dianhydrides include fluorine-containing aromatic tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

Fluorine-containing aromatic tetracarboxylic dianhydrides include 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride and 1,4-difluoropyromellitic dianhydride. , 1,4-bis(trifluoromethyl)pyromellitic dianhydride, 4-(trifluoromethyl)-1H,3H-benzo[1,2-c:4,5-c′]difuran-1,3 ,5,7-tetrone, 3,6-di[3′,5′-bis(trifluoromethyl)phenyl]pyromellitic dianhydride, 1-(3′,5′-bis(trifluoromethyl)phenyl) pyromellitic dianhydride and the like.

The alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,1'- Bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4,3',4'-dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2″- norbornane-5,5'',6,6''-tetracarboxylic dianhydride, 2,2'-binorbornane-5,5',6,6'tetracarboxylic dianhydride, and the like. From the viewpoint of transparency and mechanical strength of polyimide, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, or 1,2,4 ,5-cyclohexanetetracarboxylic dianhydride is preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is particularly preferred.

The content of pyromellitic dianhydride and/or merophanic dianhydride with respect to 100 mol% of the total amount of the acid dianhydride component is preferably 10 mol% or more, and 15 mol% from the viewpoint of compatibility with the acrylic resin. The above is more preferable, and 20 mol % or more is even more preferable. Further, the content of pyromellitic dianhydride and/or merophanic dianhydride with respect to 100 mol% of the total amount of the acid dianhydride component is preferably 50 mol% or less from the viewpoint of solubility in organic solvents, and 45 mol. % or less is more preferable, and 40 mol % or less is even more preferable.

From the viewpoint of obtaining a polyimide resin having both solubility in an organic solvent and compatibility with an acrylic resin, pyromellitic dianhydride and/or merophanic dianhydride with respect to 100 mol% of the total amount of the acid dianhydride component , 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride, bis(trimellitic anhydride) ester, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 5,5'-dimethylmethylenebis(phthalic anhydride), 3,3',4,4'-diphenylsulfonetetracarboxylic Acid dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid The content of one or more selected from anhydrides is preferably 50 mol% or more, more preferably 60 mol% or more, further preferably 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% Above, it may be 90 mol % or more, or 95 mol % or more.

The polyimide may contain an acid dianhydride other than the above as an acid dianhydride component. Examples of acid dianhydrides other than the above include ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3' ,4,4′-biphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride bis(3,4-dicarboxyphenyl)ether dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride , bis(3,4-dicarboxyphenyl)methane dianhydride, 1,3-bis[(3,4-dicarboxy)benzoyl]benzene dianhydride, 1,4-bis[(3,4-dicarboxy ) benzoyl]benzene dianhydride, 2,2-bis[4-(3,4-dicarboxy)phenoxy]phenylpropane dianhydride, 2,2-bis(4-(2,3-dicarboxy)phenoxy] phenyl}propane dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl} Ketone dianhydride, 4,4'-bis[4-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphenyl anhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride , bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfone dianhydride, bis {4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, 1,2 ,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6 ,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid)-1 , 4-phenylene esters.

(Preparation of polyimide)
A polyamic acid is obtained as a polyimide precursor by reacting an acid dianhydride and a diamine, and a polyimide is obtained by cyclodehydration (imidization) of the polyamic acid. As described above, by adjusting the composition of the polyimide, that is, the type and ratio of the acid dianhydride and the diamine, the polyimide has transparency and solubility in organic solvents, and compatibility with the acrylic resin. show.

A method for preparing polyamic acid is not particularly limited, and any known method can be applied. For example, acid dianhydride and diamine are dissolved in approximately equimolar amounts (molar ratio of 95:100 to 105:100) in an organic solvent and stirred to obtain a polyamic acid solution. The concentration of the polyamic acid solution is usually 5-35% by weight, preferably 10-30% by weight. When the concentration is within 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 polyamic acid, it is preferable to add the acid dianhydride to the diamine in order to suppress the ring opening of the acid dianhydride. When adding multiple types of diamines or multiple types of acid dianhydrides, they may be added at once or may be added in multiple batches. Various physical properties of the polyimide can also be controlled by adjusting the addition order of the monomers.

The organic solvent used for polyamic acid polymerization is not particularly limited as long as it does not react with diamines and acid dianhydrides and can dissolve polyamic acid. Examples of organic solvents include urea-based solvents such as methylurea and N,N-dimethylethylurea; sulfoxide or sulfone-based solvents such as dimethylsulfoxide, diphenylsulfone, and tetramethylsulfone; N,N-dimethylacetamide (DMAc); N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, amide solvents such as hexamethylphosphoric triamide, halogenation such as chloroform and methylene chloride Examples include alkyl solvents, aromatic hydrocarbon solvents such as benzene and toluene, and ether solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether and p-cresol methyl ether. These solvents are usually used alone or in combination of two or more as needed. DMAc, DMF, NMP and the like are preferably used from the viewpoint of the solubility and polymerization reactivity of polyamic acid.

Polyimides are obtained by cyclodehydration of polyamic acid. As a method for preparing a polyimide from a polyamic acid solution, there is a method in which a dehydrating agent, an imidization catalyst, etc. are added to the polyamic acid solution and imidization proceeds in the solution. The polyamic acid solution may be heated to accelerate imidization. By mixing a solution containing polyimide produced by imidization of polyamic acid with a poor solvent, the polyimide resin is precipitated as a solid matter. By isolating the polyimide resin as a solid, impurities generated during the synthesis of polyamic acid, residual dehydrating agent, imidization catalyst, etc. can be washed and removed with a poor solvent, resulting in polyimide coloration and yellowness. etc. can be prevented. In addition, by isolating the polyimide resin as a solid, a solvent suitable for film formation, such as a low boiling point solvent, can be applied when preparing a solution for producing a film.

The molecular weight of the polyimide (polyethylene oxide equivalent weight average molecular weight measured by gel filtration chromatography (GPC)) is preferably 10,000 to 300,000, more preferably 20,000 to 250,000, and 40,000 to 200,000 is more preferred. If the molecular weight is too small, the strength of the film may be insufficient. If the molecular weight is too large, the compatibility with the acrylic resin may be poor.

From the viewpoint of the thermal stability and light stability of the resin composition and film, the polyimide preferably has a low acid value and a high imidization rate. The acid value of polyimide is preferably 0.4 mmol/g or less, more preferably 0.3 mmol/g or less, and even more preferably 0.2 mmol/g or less. The acid value of the polyimide may be 0.1 mmol/g or less, 0.05 mmol/g or less, or 0.03 mmol/g or less. The imidization rate of the polyimide is preferably 95% or higher, more preferably 96% or higher, still more preferably 97% or higher, and may be 98% or higher and 99% or higher. A low acid value and a high imidization ratio tend to enhance the stability of the polyimide and improve the compatibility with the acrylic resin.

<Acrylic resin>
Examples of acrylic resins include poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylic acid ester copolymer, methyl methacrylate- Acrylic acid ester-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer and the like. The acrylic resin may be modified to introduce a glutarimide structural unit or a lactone ring structural unit.

From the viewpoint of transparency and compatibility with polyimide, the acrylic resin preferably has methyl methacrylate as a main structural unit. The amount of methyl methacrylate relative to the total amount of monomer components in the acrylic resin is preferably 60% by weight or more, and may be 70% by weight or more, 80% by weight or more, or 90% by weight or more. The acrylic resin may be a homopolymer of methyl methacrylate.

From the viewpoint of heat resistance of the film, the glass transition temperature of the acrylic resin is preferably 80°C or higher, preferably 90°C or higher, preferably 100°C or higher, and 105°C or higher, 110°C or higher, 115°C or higher, or 120°C or higher. There may be.

From the viewpoint of solubility in organic solvents, compatibility with the polyimide, and film strength, the weight average molecular weight (in terms of polystyrene) of the acrylic resin is preferably 5,000 to 500,000, preferably 10,000 to 300, 000 is more preferred, and 15,000 to 200,000 is even more preferred.

From the viewpoint of the thermal stability and light stability of the resin composition and film, the acrylic resin preferably contains a small amount of reactive functional groups such as ethylenically unsaturated groups and carboxyl groups. The iodine value of the acrylic resin is preferably 10.16 g/100 g (0.4 mmol/g) or less, more preferably 7.62 g/100 g (0.3 mmol/g) or less, and 5.08 g/100 g (0.2 mmol/g). /g) or less is more preferable. The iodine value of the acrylic resin may be 2.54 g/100 g (0.1 mmol/g) or less or 1.27 g/100 g (0.05 mmol/g) or less. The acid value of the acrylic resin is preferably 0.4 mmol/g or less, more preferably 0.3 mmol/g or less, and even more preferably 0.2 mmol/g or less. The acid value of the acrylic resin may be 0.1 mmol/g or less, 0.05 mmol/g or less, or 0.03 mmol/g or less. A low acid value tends to increase the stability of the acrylic resin and improve the compatibility with polyimide.

<Preparation of resin composition>
A resin composition is prepared by mixing the polyimide resin and the acrylic resin. Since the polyimide resin and the acrylic resin can exhibit compatibility at any ratio, 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 and the acrylic resin may be 98:2-2:98, 95:5-10:90, or 90:10-15:85. The higher the proportion of the polyimide resin, the higher the elastic modulus and pencil hardness of the film, which tends to be excellent in mechanical strength. The higher the proportion of the acrylic resin, the less the film is colored and the more transparent it tends to be. In order to fully exhibit the effect of improving transparency by mixing polyimide and acrylic resin, the ratio of acrylic resin to the total of polyimide and acrylic resin is preferably 10% by weight or more, 15% by weight or more, It may be 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, or 50% by weight or more.

The resin composition containing polyimide and acrylic resin preferably has a single glass transition temperature in differential scanning calorimetry (DSC) and/or dynamic viscoelasticity measurement (DMA). When the resin composition has a single glass transition temperature, it can be considered that the polyimide and the acrylic resin are completely compatible. Films containing polyimide and acrylic resins also preferably have a single glass transition temperature.

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

The solvent for the solution containing the polyimide resin and the acrylic resin is not particularly limited as long as it exhibits solubility in both the polyimide resin and the acrylic resin. Examples of solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidone; ether solvents such as tetrahydrofuran and 1,4-dioxane; acetone, methyl ethyl ketone, ketone solvents such as methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, methyl cyclohexanone; chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, Examples thereof include halogenated alkyl solvents such as dichlorobenzene and methylene chloride. Among these, amide-based solvents, ketone-based solvents, and halogenated alkyl-based solvents are preferred because they have excellent solubility in both polyimide resins and acrylic resins.

A resin composition containing polyimide and an acrylic resin has a solution viscosity lower than that of polyimide alone when compared at the same solid content concentration. By lowering the viscosity of the mixed solution containing the polyimide resin, the acrylic resin and the solvent, there are advantages such as less unevenness in the thickness of the film and easier film formation. Moreover, since the melt viscosity of the resin composition is lower than that of polyimide alone, there is an advantage that it can be used for transfer molding, compression molding, and injection molding.

An organic or inorganic low-molecular-weight or high-molecular-weight compound may be added to the resin composition (solution) for the purpose of improving the workability of the film, imparting various functions, or the like. Examples of polymer compounds include epoxy resins. The resin composition may contain flame retardants, ultraviolet absorbers, cross-linking agents, dyes, pigments, surfactants, leveling agents, plasticizers, fine particles, fiber reinforcements, sensitizers and the like. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, inorganic fine particles such as colloidal silica, carbon, and layered silicate, and the like, and may have a porous or hollow structure. Fiber reinforcements include carbon fibers, glass fibers, aramid fibers, and the like.

[the film]
A film is obtained by applying a solution containing the above polyimide resin and acrylic resin onto a support and removing the solvent by drying.

As a method for applying the resin solution onto the support, a known method using a bar coater, a comma coater, or the like can be applied. As the support, a glass substrate, a metal substrate such as SUS, a metal drum, a metal belt, a plastic film, or the like can be used. From the viewpoint of improving productivity, it is preferable to use an endless support such as a metal drum, a metal belt, or a long plastic film as the support and to produce the film by roll-to-roll. When a plastic film is used as the support, a material that does not dissolve in the solvent of the film-forming dope may be appropriately selected.

It is preferable to heat when drying the solvent. The heating temperature is not particularly limited as long as the solvent can be removed and the coloration of the resulting film can be suppressed. The heating temperature may be increased stepwise. In order to increase the removal efficiency of the solvent, the resin film may be peeled off from the support and dried after drying has progressed to some extent. Heating under reduced pressure may be used to facilitate solvent removal.

Acrylic films may have low toughness, but the use of a compatible system of polyimide and acrylic resin may improve the strength of the film. The film may be stretched in one direction or in multiple directions for the purpose of improving the mechanical strength of the film. When the film is stretched, the polymer chains are oriented in the stretching direction, so that the strength in the direction perpendicular to the stretching direction is improved, and the film tends to be prevented from breaking or cracking. From the viewpoint of increasing the strength in any in-plane direction, it is preferable to biaxially stretch the film.

The thickness of the film is not particularly limited, and may be appropriately set according to the application. The thickness of the film can be, for example, 5-300 μm. From the viewpoint of achieving both self-supporting property and flexibility and making a highly transparent film, the thickness of the film is preferably 20 μm to 100 μm, and 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 displays is preferably 50 μm or more.

The haze of the film is preferably 10% or less, more preferably 5% or less, still more 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 better. As described above, since polyimide and acrylic resin exhibit compatibility, a film with low haze and high transparency can be obtained. The resin composition obtained by mixing polyimide and acrylic resin preferably has a haze of 10% or less when a film having a thickness of 50 μm is produced.

The total light transmittance (TT) of the film when the thickness is 50 μm is preferably 85% or more, more preferably 87% or more, still more preferably 89% or more, particularly preferably 90% or more, and 91% or more. good too. The higher the TT of the film, the better. As described above, since polyimide and acrylic resin exhibit compatibility, a film with high TT and high transparency can be obtained. The resin composition obtained by mixing polyimide and acrylic resin preferably has a TT of 85% or more when a film having a thickness of 50 μm is produced. The transmittance of the film at 400 nm is preferably 50% or higher, more preferably 70% or higher, even more preferably 80% or higher, particularly preferably 85% or higher, and may be 90% or higher.

The yellowness index (YI) of the film when the thickness is 50 μm is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, particularly preferably 3.0 or less, and 2.5 or less. Alternatively, it may be 2.0 or less. As described above, by mixing the polyimide resin and the acrylic resin, a film with less coloring and a smaller YI can be obtained than when the polyimide resin is used alone. The resin composition obtained by mixing polyimide and acrylic resin preferably has a YI of 5.0 or less when a film having a thickness of 50 μm is produced.

From the viewpoint of strength, the tensile elastic modulus of the film with a thickness of 50 μm is preferably 3.0 GPa or more, and may be 3.2 GPa or more. The pencil hardness of the film having a thickness of 50 μm is preferably F or higher, and may be H or higher or 2H or higher. In a compatible system of polyimide and acrylic resin, the pencil hardness is less likely to decrease even if the proportion of acrylic resin is increased. Furthermore, it tends to be higher than the pencil hardness of polyimide alone. Therefore, it is possible to provide a film with little coloration and excellent transparency without greatly deteriorating the excellent mechanical strength peculiar to polyimide.

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

[Production example of polyimide resin]
N,N-dimethylformamide (DMF) was put into a separable flask and stirred under a nitrogen atmosphere. Diamine, acid dianhydride, and/or dicarboxylic acid compound are added thereto at the ratio (mol%) shown in Table 1, and stirred for 5 to 10 hours under a nitrogen atmosphere to react, and the solid content concentration is 18. A weight percent polyamic acid solution was obtained.

To 100 g of the polyamic acid solution, 6.0 g of pyridine was added as an imidization catalyst and dispersed completely, then 8 g of acetic anhydride was added and stirred at 90° C. for 3 hours. After cooling to room temperature, 100 g of 2-propyl alcohol (hereinafter referred to as IPA) was added at a rate of 2 to 3 drops/second while stirring the solution to precipitate polyimide. Further, 150 g of IPA was added, and after stirring for about 30 minutes, suction filtration was performed using a Kiriyama funnel. After washing the obtained solid with IPA, it was dried in a vacuum oven set at 120° C. for 12 hours to obtain a polyimide resin.

[Film production example]
<Examples 1 to 8, Comparative Examples 1 to 7>
In methylene chloride, the polyimide (PI) obtained in the above production example and a commercially available polymethyl methacrylate resin ("Parapet HM1000" manufactured by Kuraray Co., Ltd., glass transition temperature: 120 ° C., acid value: 0.0 mmol / g, Hereinafter, "acrylic resin 1") was mixed at the ratio shown in Table 1 to prepare a methylene chloride solution with a resin content of 11% by weight. This solution is applied to an alkali-free glass plate, dried by heating in an air atmosphere at 60°C for 15 minutes, 90°C for 15 minutes, 120°C for 15 minutes, 150°C for 15 minutes, and 180°C for 15 minutes, A film with a thickness of about 50 μm was produced.

<Reference example 1>
In Reference Example 1, a methylene chloride solution of acrylic resin 1 was prepared, and dried by heating in an air atmosphere at 60°C for 30 minutes, 80°C for 30 minutes, 100°C for 30 minutes, and 110°C for 30 minutes. A 50 μm film was produced.

[evaluation]
<Haze and total light transmittance>
The film was cut into 3 cm squares, and the haze and total light transmittance (TT) were measured according to JIS K7136 and JIS K7361-1 using a haze meter "HZ-V3" manufactured by Suga Test Instruments. For those with haze exceeding 15%, total light transmittance, transmittance at 400 nm, yellowness, tensile modulus and pencil hardness were not measured (denoted as ND in Table 1).

<Transmittance>
The film was cut into 3 cm squares, and the light transmittance was measured using a UV-visible spectrophotometer (V-770) manufactured by JASCO Corporation.

<Yellowness>
The film was cut into a 3 cm square, and the yellowness index (YI) was measured according to JIS K7373 using a spectrophotometer "SC-P" manufactured by Suga Test Instruments.

<Tensile modulus>
Cut the film into strips with a width of 10 mm, leave it at 23 ° C./55% RH for 1 day to condition the humidity, and then use Shimadzu's "AUTOGRAPH AGS-X" to measure the tensile modulus under the following conditions. It was measured.
Distance between grips 100mm
Tensile speed; 20.0mm/min
Measurement temperature; 23°C

<Pencil hardness>
The pencil hardness of the film was measured according to JIS K5600-5-4 “Pencil Scratch Test”.

<Bending resistance>
The film was cut into strips of 20 mm x 100 mm and bent 180° at the center in the length direction.

<Polyamide Solvent Solubility>
DMF was added to the polyimide resin so that the solid content concentration was 10 wt %, the mixture was stirred at room temperature for 72 hours, and the solution was visually confirmed. When solid content could be confirmed, it was regarded as insoluble.

[Evaluation results]
Table 1 shows the resin composition (polyimide composition, type of acrylic resin, and mixing ratio) and evaluation results of the film.

In Table 1, compounds are described by the following abbreviations.
<Acid dianhydride>
PMDA: pyromellitic dianhydride MPDA: melophanic dianhydride ODPA: 4,4'-oxydiphthalic anhydride TMHMBP: bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)- 2,2′,3,3′,5,5′-Hexamethylbiphenyl-4,4′diyl BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene diacid anhydride BPADA: 4,4 '-(4,4'-isopropylidenediphenoxy) diphthalic anhydride 6FDA: 4,4'-(hexafluoroisopropylidene) diphthalic anhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride Thing <diamine>
TFMB: 2,2'-bis(trifluoromethyl)benzidine 3,3'-DDS: 3,3'-diaminodiphenylsulfone <dicarboxylic acid compound>
TPC: terephthalic acid chloride

Polyimide resin and acrylic resin 1 containing fluoroalkyl-substituted benzine in the diamine-derived structure, PMDA or MPDA in the tetracarboxylic dianhydride-derived structure, and at least one or more from ODPA, TAHMBP, BPAF, BPADA, and 6FDA In Examples 1 to 8 using the resin composition mixed with, the increase in haze was suppressed as compared to Comparative Examples 1 to 4. In Examples 1 to 8, compared with Reference Example 1, the tensile modulus, pencil hardness and bending resistance were improved.

The acrylic film of Reference Example 1 produced using only acrylic resin 1 had a low tensile modulus, a pencil hardness of HB, and insufficient mechanical strength.

In Comparative Examples 1 to 4 using a resin composition obtained by mixing a polyimide resin that does not contain PMDA and/or MPDA with acrylic resin 1, the haze of the film is greatly increased, and the bending resistance is insufficient. there were. This is probably because the polyimide resin and the acrylic resin did not exhibit compatibility.

In Examples 2 and 3, which are films containing a polyimide resin and an acrylic resin, yellowness, transmittance, and pencil hardness were improved as compared with Reference Examples 2 and 3, which were films made only of a polyimide resin.

Since the polyimide resins shown in Comparative Examples 5 and 6 are insoluble in DMF, they could not be mixed with the acrylic resin.

From the above results, a polyimide containing a fluoroalkyl-substituted benzidine in a diamine-derived structure, containing PMDA and/or MPDA in a tetracarboxylic dianhydride-derived structure, and soluble in an amide solvent is an acrylic resin. It can be seen that by using a resin composition in which these are mixed, a film having high transparency and excellent mechanical strength can be obtained.

Claims (17)

A resin composition containing polyimide and acrylic resin,
The polyimide has a tetracarboxylic dianhydride-derived structure and a diamine-derived structure, and the diamine-derived structure contains a fluoroalkyl-substituted benzidine,
Including pyromellitic dianhydride and / or merophanic dianhydride in the structure derived from the tetracarboxylic dianhydride,
A resin composition that is soluble in an amide solvent. The structure derived from the tetracarboxylic dianhydride further includes 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride, bis(trimellitic anhydride) ester, 9,9-bis(3, 4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 5,5'-dimethylmethylenebis(phthalic anhydride), 3, 3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3′,4,4′-tetracarboxylic dianhydride, 4 ,4'-(hexafluoroisopropylidene)diphthalic anhydride and 1,2,3,4-cyclobutanetetracarboxylic dianhydride, the resin composition according to claim 1. .
3. The resin composition according to claim 2, wherein the bis(trimellitic anhydride) ester is represented by the following general formula (1).
(However, X in general formula (1) is a divalent organic group selected from (A) to (K) below.)

2. The resin composition according to claim 1, wherein the amount of pyromellitic dianhydride and/or melophanic dianhydride is 10 mol % to 50 mol %. 2. The resin composition according to claim 1, wherein said fluoroalkyl-substituted benzidine is 2,2'-bis(trifluoromethyl)benzidine. 2. The resin composition according to claim 1, wherein the amount of fluoroalkyl-substituted benzidine in the diamine-derived structure of said polyimide is 50 mol % or more. 2. The resin composition according to claim 1, wherein the diamine-derived structure is a condensation structure of 2,2'-bis(trifluoromethyl)benzidine and dicarboxylic acid. 8. The resin composition according to claim 7, wherein the dicarboxylic acid is one or more selected from terephthalic acid, isophthalic acid and biphenyl-4,4'-dicarboxylic acid. The resin composition according to claim 7, wherein the condensed structure of 2,2'-bis(trifluoromethyl)benzidine and dicarboxylic acid accounts for 10 to 100 mol% of the diamine-derived structure. The resin composition according to claim 8, wherein the condensed structure of 2,2'-bis(trifluoromethyl)benzidine and dicarboxylic acid accounts for 10 to 100 mol% of the diamine-derived structure. pyromellitic dianhydride and/or merophanic dianhydride and 4,4′-oxydiphthalic anhydride or 3,4′-oxydiphthalic anhydride in the tetracarboxylic dianhydride-derived structure of the polyimide; bis(trimellitic anhydride) ester, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride, 5,5′-dimethylmethylenebis(phthalic anhydride), 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3 ,3′,4,4′-tetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride. 2. The resin composition according to claim 1, wherein the total amount of the one or more types is 50 mol % or more. 2. The resin composition according to claim 1, wherein the acrylic resin contains 60% by weight or more of methyl methacrylate with respect to the total amount of monomer components. The resin composition according to claim 1, wherein the acrylic resin has a glass transition temperature of 80°C or higher. 2. The resin composition according to claim 1, comprising said polyimide and said acrylic resin in a weight ratio ranging from 98:2 to 2:98. A film comprising the resin composition according to any one of claims 1 to 14. 16. The film according to claim 15, having a thickness of 5 μm or more and 300 μm or less. 16. When the thickness is 50 μm, the total light transmittance is 85% or more, the haze is 10% or less, the yellowness is 5.0 or less, the tensile modulus is 3.2 GPa or more, and the pencil hardness is F or more. Film as described.