JP7833331B2 - Resin compositions, molded articles, and films - Google Patents

Description

This invention relates to resin compositions and films.

Display devices such as liquid crystal displays (LCDs), organic EL displays (OLEDs), and electronic paper, as well as electronic devices such as solar cells and touch panels, are required to be thinner, lighter, and more flexible. Replacing the glass materials used in these devices with film materials can achieve flexibility, thinning, and weight reduction. Transparent polyimide film has been developed as a glass substitute and is used in display substrates and cover films.

Conventional polyimide films are obtained by coating a polyamic acid solution, a polyimide precursor, onto a support in a film-like manner and then subjecting it to high-temperature treatment, thereby removing the solvent and simultaneously performing thermal imidization. However, the heating temperature required for thermal imidization is high (e.g., 300°C or higher), and discoloration (increase in yellowness) is likely to occur due to heating, making it difficult to apply to applications requiring high transparency, such as display cover films.

As a method for producing highly transparent polyimide films, a method using a polyimide resin that is soluble in organic solvents and does not require high-temperature imidation after film formation has been proposed. For example, Patent Document 1 describes a polyimide containing bis-trimellitic anhydride esters as a tetracarboxylic dianhydride component, which exhibits excellent solubility in organic solvents, as well as excellent transparency and mechanical strength.

International Publication No. 2020/004236

While introducing a rigid structure to polyimide improves its mechanical strength, it also reduces its solubility in organic solvents and can cause discoloration. Therefore, achieving both transparency and high mechanical strength with polyimide alone is not easy. In view of these challenges, the present invention aims to provide a resin composition that can achieve both excellent mechanical strength and transparency.

One aspect of the present invention relates to a resin composition comprising a polyimide and an acrylic resin. The resin composition may contain the polyimide and the acrylic resin in a weight ratio in the range of 98:2 to 2:98. Preferably, the polyimide and acrylic resin in the resin composition are miscible in dimethylformamide. The resin composition may also be miscible in solvents other than dimethylformamide.

The polyimide has a diamine-derived structure represented by general formula (IIa) and a tetracarboxylic dianhydride-derived structure represented by general formula (IIIa), wherein at least one of the diamine-derived structure and the tetracarboxylic dianhydride-derived structure has a fluoroalkyl group. Preferably, the diamine-derived structure includes a structure derived from a diamine having a fluoroalkyl group.

Y is a divalent organic group and is a diamine residue. X is a tetravalent organic group and is a tetracarboxylic dianhydride residue.

Polyimides may contain structures derived from diamines and tetracarboxylic dianhydrides, as well as structures derived from dicarboxylic acids represented by the general formula (Va).

Z is a divalent organic group, specifically a dicarboxylic acid residue.

Preferably, the polyimide includes, as a diamine-derived structure, a structure derived from a diamine having a fluoroalkyl group, and as a tetracarboxylic dianhydride-derived structure, one or more selected from the group consisting of a structure derived from a tetracarboxylic dianhydride having a fluoroalkyl group, a structure derived from a bis(trimellitic anhydride) ester, and a structure derived from a tetracarboxylic dianhydride having an ether linkage.

Examples of diamines having a fluoroalkyl group include fluoroalkyl-substituted benzidines such as 2,2'-bis(trifluoromethyl)benzidine. Examples of tetracarboxylic dianhydrides having a fluoroalkyl group include 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride. Examples of bis(trimellitic anhydride) esters include compounds represented by formula (3).

The ratio of structures derived from diamines having fluoroalkyl groups to the total amount of diamine-derived structures in the polyimide is preferably 50 mol% or more. The total ratio of structures derived from tetracarboxylic dianhydrides having fluoroalkyl groups, structures derived from bis(trimellitic anhydride) esters, and structures derived from tetracarboxylic dianhydrides having ether links to the total amount of tetracarboxylic dianhydride-derived structures in the polyimide is preferably 40 mol% or more.

Because the polyimide and acrylic resin contained in the resin composition are compatible, molded articles such as films with low haze and high transparency can be produced.

This diagram shows the protocol in BIOVIA Pipeline Pilot Polymer Properties.

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

<Polyimide>
Polyimide is a polymer having a structural unit represented by general formula (I), and is obtained by dehydrating and cyclizing polyamic acid, which is obtained by addition polymerization of tetracarboxylic dianhydride (hereinafter sometimes referred to as "acid dianhydride") and diamine. In other words, polyimide is a polycondensate of tetracarboxylic dianhydride and diamine, and has an acid dianhydride-derived structure (acid dianhydride component) and a diamine-derived structure (diamine component). Polyimide can also be synthesized by decarboxylation condensation of diisocyanate and acid dianhydride.

In general formula (I), Y is a divalent organic group, and X is a tetravalent organic group. Y is a diamine residue, an organic group obtained by removing two amino groups from the diamine represented by general formula (II) below. Note that when synthesizing polyimide using diisocyanate, Y is a diisocyanate residue, an organic group obtained by removing two isocyanate groups from the diisocyanate compound. X is a tetracarboxylic dianhydride residue, an organic group obtained by removing two anhydride carboxyl groups from the tetracarboxylic dianhydride represented by general formula (III) below.

In other words, polyimide contains structural units represented by the following general formula (IIa) and structural units represented by the following general formula (IIIa). The diamine-derived structure (IIa) and the tetracarboxylic dianhydride-derived structure (IIIa) form imide bonds, resulting in the structural unit represented by general formula (I).

Polyimides may contain not only the imide structural units represented by general formula (I), but also structural units represented by general formula (IV) below (amide structural units). Polyimides containing amide structural units in addition to imide structural units are also called polyamideimides.

In general formula (IV), Y and Z are divalent organic groups. Y is a diamine residue, similar to general formula (I). Z is a dicarboxylic acid residue, an organic group obtained by removing two carboxyl groups from a dicarboxylic acid represented by general formula (V) below. In the synthesis of polyamide-imides, dicarboxylic acid dichlorides represented by general formula (V') are preferably used instead of dicarboxylic acids. Dicarboxylic acid anhydrides may also be used instead of dicarboxylic acids.

The amide structural unit represented by general formula (V) is formed when the diamine-derived structure represented by the above general formula (IIa) and the dicarboxylic acid-derived structure represented by the following general formula (Va) form an amide bond. That is, polyamide-imide contains a diamine-derived structure (IIa), a tetracarboxylic dianhydride-derived structure (IIIa), and a dicarboxylic acid-derived structure (Va).

Furthermore, polyamide-imides contain the structure shown in the following general formula (VI), in which a dicarboxylic acid-derived structure (Va) is bonded to both ends of a diamine-derived structure (IIa).

In general formula (VI), _Y1 and _Y2 are diamine residues, and _Z1 is a dicarboxylic acid residue. If we consider the portion [ _-Y1 -NH-CO- _Z1 -CO-NH- _Y2- ] in general formula (VI) as a single divalent organic group, this divalent organic group can be considered as diamine residue Y containing two amide bonds. That is, in general formula (I), a polyimide in which diamine residue Y contains an amide bond is a polyamideimide, and polyamideimide can be said to be a type of polyimide. Hereafter, unless otherwise specified, the term "polyimide" includes "polyamideimide".

As mentioned above, polyimides contain a diamine-derived structure (diamine component) and an acid dianhydride-derived structure (acid dianhydride component). The polyimide used in this embodiment has at least one of the diamine-derived structure and the tetracarboxylic dianhydride-derived structure having a fluoroalkyl group. That is, the monomer components constituting the polyimide include a diamine having a fluoroalkyl group and/or an acid dianhydride having a fluoroalkyl group.

(Diamines containing fluoroalkyl groups)
Examples of diamines having a fluoroalkyl group include fluoroalkyl-substituted benzidines. Specific 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, and 2,3'-bis(trifluoro Examples include methyl(benzidine), 2,2',3-bis(trifluoromethyl)benzidine, 2,3,3'-tris(trifluoromethyl)benzidine, 2,2',5-tris(trifluoromethyl)benzidine, 2,2',6-tris(trifluoromethyl)benzidine, 2,3',5-tris(trifluoromethyl)benzidine, 2,3',6-tris(trifluoromethyl)benzidine, 2,2',3,3'-tetrakis(trifluoromethyl)benzidine, 2,2',5,5'-tetrakis(trifluoromethyl)benzidine, and 2,2',6,6'-tetrakis(trifluoromethyl)benzidine.

Among these, fluoroalkyl-substituted benzidines having a fluoroalkyl group at the 2-position of biphenyl are preferred, and 2,2'-bis(trifluoromethyl)benzidine (hereinafter referred to as "TFMB") is particularly preferred. Having fluoroalkyl groups at the 2- and 2' positions of biphenyl reduces the π-electron density due to the electron-withdrawing properties of the fluoroalkyl group. Furthermore, the steric hindrance of the fluoroalkyl group causes the bond between the two benzene rings of biphenyl to twist, reducing the planarity of the π-conjugation. This shifts the absorption edge wavelength to a shorter wavelength, reducing the coloration of the polyimide and tending to improve its solubility in organic solvents.

Examples of diamines having fluoroalkyl groups other than fluoroalkyl-substituted benzidines include diamines having aromatic rings to which fluoroalkyl groups are bonded, such as 1,4-diamino-2-(trifluoromethyl)benzene, 1,4-diamino-2,3-bis(trifluoromethyl)benzene, 1,4-diamino-2,5-bis(trifluoromethyl)benzene, 1,4-diamino-2,6-bis(trifluoromethyl)benzene, 1,4-diamino-2,3,5-tris(trifluoromethyl)benzene, and 1,4-diamino, 2,3,5,6-tetrakis(trifluoromethyl)benzene; and diamines having fluoroalkyl groups not directly bonded to the aromatic ring, such as 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

As the diamine, a diamine containing a condensation structure of a diamine with a fluoroalkyl group and a dicarboxylic acid may be used. As described above, the amide formed by bonding diamines to both ends of a dicarboxylic acid contains the structure of general formula (IV) and has amino groups at both ends, so it can also be considered a diamine containing an amide structure. Therefore, a condensate of a diamine with a fluoroalkyl group and a dicarboxylic acid can also be considered a type of diamine containing a fluoroalkyl group.

While general formula (VI) shows a structure in which one dicarboxylic acid and two diamines are condensed, it may also be a structure in which two dicarboxylic acids and three diamines are condensed, or a structure in which three or more dicarboxylic acids and four or more diamines are condensed.

Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-oxybisbenzoic acid, biphenyl-4,4'-dicarboxylic acid, and 2-fluoroterephthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid and 2,5-franzicarboxylic acid. In the preparation of compounds containing a condensation structure of a diamine and a dicarboxylic acid, dicarboxylic acid dichlorides or dicarboxylic acid anhydrides may be used instead of dicarboxylic acids.

Specific examples of diamines containing a condensation structure of a diamine with a fluoroalkyl group and a dicarboxylic acid include condensates of fluoroalkyl-substituted benzidines such as TFMB and dicarboxylic acids. Terephthalic acid and/or isophthalic acid are particularly preferred as the dicarboxylic acid. For example, a diamine in which TFMB is condensed at both ends of terephthalic acid has the structure of formula (4) below.

(Acid dianhydrides containing fluoroalkyl groups)
Examples of tetracarboxylic dianhydrides having a fluoroalkyl group include 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}-1,1,1,3,3,3-hexafluoropropane dianhydride, 1,4-bis(trifluoromethyl)pyromellitic acid dianhydride, and 4-trifluoromethylpyromellitic acid di Examples include anhydrides, 3,6-di[3',5'-bis(trifluoromethyl)phenyl]pyromellitic dianhydride, 1-[3',5'-bis(trifluoromethyl)phenyl]pyromellitic dianhydride, N,N'-[[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis(6-hydroxy-3,1-phenylene)]bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], etc. Among these, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (hereinafter referred to as "6FDA") is particularly preferred.

(Other diamines)
Polyimides may contain diamines without fluoroalkyl groups as diamine components. Examples of diamine components without fluoroalkyl groups that exhibit excellent compatibility with acrylic resins include diamines having an alicyclic structure, diamines having a fluorene structure, diamines having a sulfone group, and diamines having a fluorine-containing group other than a fluoroalkyl group.

Examples of diamines having an alicyclic structure include isophorone diamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornene, 4,4'-methylenebis(cyclohexylamine), bis(4-aminocyclohexyl)methane, 4,4'-methylenebis(2-methylcyclohexylamine), adamantane-1,3-diamine, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, and 1,1-bis(4-aminophenyl)cyclohexane.

An example of a diamine having a fluorene structure is 9,9-bis(4-aminophenyl)fluorene.

Examples of diamines having a sulfone group include 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, bis[4-(3-aminophenoxy)phenyl] sulfone, bis[4-(4-aminophenoxy)phenyl] sulfone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy] diphenyl sulfone, and 4,4'-bis[4-(4-aminophenoxy)phenoxy] diphenyl sulfone. Among these, diaminodiphenyl sulfones such as 3,3'-diaminodiphenyl sulfone and 4,4'-diaminodiphenyl sulfone are preferred.

Examples of fluorine-containing diamines 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, 2,2'-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, and 2,3',6-trifluorobenzidine. Examples include din, 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, 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, and 2,2'-dimethylbenzidine.

Examples of diamines other than those listed above include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, p-xylenediamine, m-xylenediamine, o-xylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, and 3,3'-diaminoben Zophenone, 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)bis(4-aminophenoxy) Phenyl, 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]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, 3,3'-diamino-4,4' Examples of aromatic diamines include -diphenoxybenzophenone, 3,3'-diamino-4,4'-diviphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobidane, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobidane.

Diamines include bis(aminomethyl) ether, bis(2-aminoethyl) ether, bis(3-aminopropyl) ether, bis(2-aminomethoxy)ethyl ether, bis[2-(2-aminoethoxy)ethyl] ether, bis[2-(3-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 Chain-like diamines such as rubis(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, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, and α,ω-bis(3-aminobutyl)polydimethylsiloxane can also be used.

(Other acid dianhydrides)
Polyimide may contain an acid dianhydride without a fluoroalkyl group as an acid dianhydride component. Among acid dianhydrides without a fluoroalkyl group, bis(trimellitic anhydride) ester is an example of an acid dianhydride with excellent compatibility with acrylic resins. Bis(trimellitic anhydride) ester is represented by the following general formula (1).

In general formula (1), Q is any divalent organic group, with carboxyl groups bonded to the carbon atoms of Q at both ends. The carbon atoms bonded to the carboxyl groups may form a ring structure. Specific examples of divalent organic group Q are listed below (A) to (K).

In formula (A), ^R1 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 from 1 to 4. The group represented by formula (A) is a hydroquinone derivative having substituents on a benzene ring, with two hydroxyl groups removed. Examples of hydroquinones having substituents on a benzene ring include tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and 2,5-di-tert-amylhydroquinone. When ^R1 is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester corresponds to a tetracarboxylic dianhydride having a fluoroalkyl group.

In formula (B), ^R2 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 from 0 to 4. The group represented by formula (B) is a biphenol which may have substituents on the benzene ring, with two hydroxyl groups removed. Examples of biphenol derivatives having substituents 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, and 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diol. When ^R2 is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester corresponds to a tetracarboxylic dianhydride having a fluoroalkyl group.

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

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

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

In formula (G), ^R3 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 from 0 to 4. The group represented by formula (G) is a group obtained by removing two hydroxyl groups from bisphenol fluorene, which may have substituents on a benzene ring having phenolic hydroxyl groups. Examples of bisphenol fluorene derivatives having substituents on a benzene ring having phenolic hydroxyl groups include biscresol fluorene. When ^R3 is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester corresponds to a tetracarboxylic dianhydride having a fluoroalkyl group.

The bis(trimellitic anhydride) ester is preferably an aromatic ester, and among (A) to (K) above, (A), (B), (C), (D), (G), (H), and (I) are preferred as Q. Of these, (A) to (D) are preferred, and (B) and (C) are particularly preferred. When Q is a group represented by general formula (B), from the viewpoint of polyimide solubility, Q is preferably 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl represented by the following formula (B1).

In general formula (1), the acidic dianhydride in which Q is the group represented by formula (B1) is bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'diyl (abbreviation: TAHMBP), represented by the following formula (3).

In addition to the above, examples of acid dianhydride components with excellent compatibility with acrylic resins include alicyclic tetracarboxylic dianhydrides, acid dianhydrides having ether bonds, and aromatic acid dianhydrides. Alicyclic tetracarboxylic dianhydrides only need to have at least one alicyclic structure, and may have both alicyclic and aromatic rings in a single molecule. The alicyclic ring may be polycyclic and may have a spiro structure.

Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, meso-butane-1,2,3,4-tetracarboxylic dianhydride, and 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic-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, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride, bicyclo[2.2.2]octa-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, cyclohexane-1,4-diylbis(methylene)bis(1,3-dioxy So-1,3-dihydroisobenzofuran-5-carboxylate), 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 5,5'-[cyclohexyllidenebis(4,1-phenyleneoxy)]bis-1,3-isobenzofranion, 5-isobenzofurancarboxylic acid, 1,3-dihydro-1,3-dioxo-,5,5'-[1,4-cyclohexanediylbis(methylene)]ester, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid dianhydride, 3 Examples include 5,6-tricarboxynorbornane-2-acetic acid 2,3:5,6-dianhydride, decahydro-1,4,5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid dianhydride, tricyclo[6.4.0.0(2,7)]dodecane-1,8:2,7-tetracarboxylic acid dianhydride, octahydro-1H,3H,8H,10H-biphenyleno[4a,4b-c:8a,8b-c']difuran-1,3,8,10-tetron, ethylene glycol bis(hydrogenated trimellitic anhydride) ester, decahydro[2]benzopyrano[6,5,4,-def][2]benzopyran-1,3,6,8-tetron, etc.

Among alicyclic tetracarboxylic dianhydrides, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA), or 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic-3,4:3',4'-dianhydride (H-BPDA) are preferred from the viewpoint of polyimide transparency and mechanical strength, with 1,2,3,4-cyclobutanetetracarboxylic dianhydride being particularly preferred.

Examples of acid dianhydrides having ether bonds that exhibit excellent compatibility with acrylic resins include 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride. Among these ether-bonded acid dianhydrides, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride is preferred from the viewpoint of compatibility with acrylic resins.

Aromatic acid anhydrides that have excellent compatibility with acrylic resins as acid dianhydrides include pyromellitic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 5,5'-dimethylmethylenebis(phthalic acid anhydride), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, terphenyltetracarboxylic acid dianhydride, Examples include 9,9-bis(3,4-dicarboxyphenyl)fluorenodioanhydride, N,N'-(9H-fluorene-9-ylidenedi-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 11,11-dimethyl-1H-difluoro[3,4-b:3',4'-i]xanthene-1,3,7,9(11H)-tetron, and 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride.

Examples of aromatic acid dianhydrides other than those listed above include 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, and 1,3-bis[(3,4-dicarboxy)benzoyl]be Benzene dianhydride, 1,4-bis[(3,4-dicarboxy)benzoyl]benzene dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride, 2,2-bis{4-[4-(3,4-dicarboxy)phenoxy]phenyl}propane dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl} Ketone dianhydride, 4,4'-bis[4-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]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 Examples include {4-[4-(1,2-dicarboxy)phenoxy]phenyl} sulfide dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl} sulfide dianhydride, 1,2,3,4-benzenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracenetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, and bis(1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid)-1,4-phenylene ester. As the acid dianhydride, chain-like aliphatic acid dianhydrides such as ethylenetetracarboxylic acid dianhydride and butanetetracarboxylic acid dianhydride may also be used.

(Dicarboxylic acid)
As mentioned above, polyimides may also be polyamide-imides containing structures derived from dicarboxylic acids represented by the general formula (Va). Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-oxybisbenzoic acid, biphenyl-4,4'-dicarboxylic acid, and 2-fluoroterephthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, and 1,3-cyclopentanedicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid and 2,5-franzicarboxylic acid. As the dicarboxylic acid, terephthalic acid and/or isophthalic acid are preferred, and terephthalic acid is particularly preferred.

In the preparation of polyamide-imides (polyimides containing structures derived from dicarboxylic acids), it is preferable to use dicarboxylic acid dichlorides as monomers. Alternatively, as described above, polyimides may be prepared using compounds obtained by condensing dicarboxylic acids (or derivatives such as dicarboxylic acid dichlorides) with diamines as monomers.

(Composition of polyimide)
As described above, the polyimide used in this embodiment contains a fluoroalkyl group in at least one of the diamine and the dianhydride. Both a diamine containing a fluoroalkyl group and a dianhydride containing a fluoroalkyl group may be used. The inclusion of a fluoroalkyl group in at least one of the dianhydride and the diamine tends to improve solubility in organic solvents and compatibility with acrylic resins.

In particular, because it exhibits compatibility with acrylic resins in a variety of solvents, polyimides preferably contain a diamine having a fluoroalkyl group as the diamine component, and preferably contain a fluoroalkyl-substituted benzidine such as TFMB. The ratio of the diamine having a fluoroalkyl group to the total amount of the diamine component in the polyimide is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, and may be 80 mol% or more, 85 mol% or more, or 90 mol% or more. The amount of fluoroalkyl-substituted benzidine is preferably within the above range, and the amount of TFMB is particularly preferably within the above range.

When polyimide contains a diamine without a fluoroalkyl group as a diamine component, preferred diamines without a fluoroalkyl group include diamines with an alicyclic structure, diamines with an ether structure, diamines with a fluorine structure, diamines with a sulfone group, and diamines with a fluorine-containing group other than a fluoroalkyl group. Diamines with an alicyclic structure, diamines with an ether structure, diamines with a fluorine-containing group other than a fluoroalkyl group, and diamines with a fluorine structure are not necessarily included, and their presence may be 10 mol% or more, 30 mol% or more, 50 mol% or 70 mol% or more, or 100 mol% or more, respectively, relative to the total amount of diamine components in the polyimide. Diamines with a sulfone group are preferably present in amounts of 40 mol% or less, preferably 30 mol% or less, and may be present in amounts of 20 mol% or 10 mol% or less, or may not be present at all, relative to the total amount of diamine components in the polyimide. If the molar ratio of diamines with a sulfone group is too high, the compatibility with acrylic resin may deteriorate.

If the polyimide does not contain a diamine having a fluoroalkyl group as its diamine component, it is necessary to include an acid dianhydride having a fluoroalkyl group as the acid dianhydride component to ensure compatibility with acrylic resins. In this case, the ratio of acid dianhydride having a fluoroalkyl group to the total amount of acid dianhydride component in the polyimide is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and may be 70 mol% or more, 80 mol% or more, or 90 mol% or more. Among these, it is particularly preferable that the amount of 6FDA be within the above range.

If the polyimide contains a diamine having a fluoroalkyl group as the diamine component, it does not need to contain an acid dianhydride having a fluoroalkyl group as the acid dianhydride component. Even if the polyimide contains a diamine having a fluoroalkyl group as the diamine component, it may still contain an acid dianhydride having a fluoroalkyl group as the acid dianhydride component. Furthermore, if the acid dianhydride component does not contain an acid dianhydride having a fluoroalkyl group, it is preferable that the acid dianhydride component contains a bis(trimellitic anhydride) ester or an acid dianhydride having an ether structure. That is, it is preferable that the polyimide contains at least one of the following as the acid dianhydride component: an acid dianhydride having a fluoroalkyl group, a bis(trimellitic anhydride) ester, and an acid dianhydride having an ether structure. As mentioned above, 6FDA is preferred as the acid dianhydride having a fluoroalkyl group, TAHMBP is preferred as the bis(trimellitic anhydride) ester, and BPADA is preferred as the acid dianhydride having an ether bond.

The ratio of the total amount of tetracarboxylic acid dianhydrides having a fluoroalkyl group, bis(trimellitic anhydride) esters, and ether-structured dianhydrides to the total amount of acid dianhydride components in the polyimide is preferably 40 mol% or more, more preferably 50 mol% or more, and may be 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more.

When the polyimide contains acid dianhydrides other than acid dianhydrides having a fluoroalkyl group, bis(trimellitic anhydride) esters, and acid dianhydrides having an ether structure as acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides and the aforementioned aromatic tetracarboxylic acid dianhydrides are preferred as acid dianhydride components with excellent compatibility with acrylic resins. The total amount of acid dianhydrides having a fluoroalkyl group, bis(trimellitic anhydride) esters, acid dianhydrides having an ether structure, alicyclic tetracarboxylic acid dianhydrides, and the aforementioned aromatic tetracarboxylic acid dianhydrides is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and may be 95 mol% or more or 100 mol% based on the total amount of acid dianhydride components in the polyimide.

When the polyimide contains a dicarboxylic acid-derived structure represented by general formula (Va), i.e., a polyamide-imide, the amount of the dicarboxylic acid-derived structure may be 10 moles or more, 20 moles or more, 30 moles or more, or 40 moles or more per 100 moles of the tetracarboxylic dianhydride-derived structure represented by general formula (IIIa). Preferably, the amount of the dicarboxylic acid-derived structure is 250 moles or less, more preferably 200 moles or less, and may also be 100 moles or less, 80 moles or less, 60 moles or less, or 50 moles or less per 100 moles of the tetracarboxylic dianhydride-derived structure.

As the proportion of dicarboxylic acid-derived structures increases, solubility in organic solvents tends to improve. On the other hand, if the proportion of dicarboxylic acid-derived structures is excessively high, it may lead to decreased compatibility with acrylic resins and reduced heat resistance of the resin composition.

(Preparation of polyimide)
Polyamic acid, a precursor to polyimide, is obtained by the reaction of an acidic dianhydride with a diamine, and polyimide is obtained by dehydration cyclization (imidization) of the polyamic acid. The method for preparing polyamic acid is not particularly limited, and any known method can be applied. For example, a polyamic acid solution can be obtained by dissolving a diamine and a tetracarboxylic dianhydride in approximately equimolar amounts (molar ratio of 95:100 to 105:100) in an organic solvent and stirring.

When preparing polyamide-imides, polyamide-imides can be prepared using diamines and tetracarboxylic dianhydrides, along with dicarboxylic acids or their derivatives (dicarboxylic acid dichlorides, dicarboxylic acid anhydrides, etc.) as monomers. In this case, the amounts of each monomer should be adjusted so that the total amount of tetracarboxylic dianhydrides and dicarboxylic acids or their derivatives is approximately equivalent to the amount of diamine.

The concentration of the polyamic acid solution is typically 5 to 35% by weight, preferably 10 to 30% by weight. Within this concentration 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 acids, it is preferable to add the dianhydride to the diamine to suppress ring-opening of the dianhydride. When adding multiple types of diamines or dianhydrides, they may be added all at once or in multiple stages. The properties of the polyimide can also be controlled by adjusting the order of monomer addition.

The organic solvent used for polymerization of polyamic acid is not particularly limited, as long as it does not react with diamines and acidic 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 dimethyl sulfoxide, diphenyl sulfone, and tetramethylsulfone; amide-based solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, and hexamethylphosphate triamide; alkyl halogenated solvents such as chloroform and dichloromethane; aromatic hydrocarbon solvents such as benzene and toluene; and ether-based solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, and p-cresol methyl ether. These solvents are usually used individually or in appropriate combinations of two or more as needed. From the viewpoint of polyamic acid solubility and polymerization reactivity, DMAc, DMF, NMP, etc., are preferably used.

Polyimides are obtained by the dehydration and cyclization of polyamic acids. One method for preparing polyimides from a polyamic acid solution involves adding a dehydrating agent, an imidation catalyst, etc., to the polyamic acid solution and allowing imidation to proceed in the solution. The polyamic acid solution may be heated to accelerate the imidation process. By mixing the solution containing the polyimide produced by the imidation of polyamic acid with a poor solvent, the polyimide precipitates as a solid. Isolating the polyimide as a solid allows for the washing and removal of impurities generated during the synthesis of polyamic acid, as well as residual dehydrating agents and imidation catalysts, using a poor solvent, thus preventing discoloration and increased yellowness of the polyimide. Furthermore, isolating the polyimide as a solid allows for the application of solvents suitable for film formation, such as low-boiling point solvents, when preparing solutions for producing molded articles such as films.

The molecular weight of the polyimide (weight-average molecular weight in terms of polyethylene oxide, measured by gel filtration chromatography (GPC)) is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, and even more preferably 40,000 to 300,000. If the molecular weight is excessively low, the film strength may be insufficient. If the molecular weight is excessively high, compatibility with acrylic resins may be poor, and film-forming properties may be poor.

From the viewpoint of thermal and photostability of the resin composition and film, polyimide is preferably low in reactivity. 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 polyimide may also be 0.1 mmol/g or less, 0.05 mmol/g or less, or 0.03 mmol/g or less. From the viewpoint of reducing the acid value, polyimide is preferably high in imidization rate. A low acid value tends to improve the stability of polyimide and enhance its compatibility with acrylic resins.

<Acrylic resin>
Examples of acrylic resins include poly(meth)acrylic acid esters 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, and (meth)acrylic acid-styrene copolymers. The acrylic resin may also be an acrylic polymer in which a glutarimide structure or a lactone ring structure has been introduced into an acrylic polymer having a methyl methacrylate content within the above range.

Introducing a glutarimide structure into acrylic polymers such as methyl methacrylate tends to improve the glass transition temperature of the acrylic resin. Furthermore, because the acrylic resin contains an imide structure, its compatibility with polyimides may improve. For example, a particular polyimide resin may not be compatible with polymethyl methacrylate, but may be compatible with an acrylic resin containing a glutarimide structure. An acrylic resin containing a glutarimide structure can be obtained, for example, by heating and melting a polymethyl methacrylate resin and treating it with an imidizing agent, as described in Japanese Patent Application Publication No. 2010-261025.

When an acrylic polymer has a glutarimide structure, the glutarimide content may be 3% by weight or more, 10% by weight or more, 20% by weight or more, 30% by weight or more, or 50% by weight or more. The glutarimide content can be calculated from the ^1H -NMR spectrum of the acrylic resin, determining the imidation rate Im = B/(A + B) from the area A of the peak derived from the O- _CH3 proton of methyl methacrylate and the area B of the peak derived from the N- _CH3 proton of glutarimide, and then converting the imidation rate to weight. By introducing a glutarimide structure into an acrylic resin, improved compatibility with polyimide and improved elastic modulus of the resulting molded article can be expected.

From the viewpoint of heat resistance of the resin composition and molded article, the glass transition temperature of the acrylic resin is preferably 100°C or higher, more preferably 110°C or higher, and may also be 115°C or higher or 120°C or higher.

From the viewpoint of solubility in organic solvents, compatibility with the above-mentioned polyimide, and strength of the molded article, the weight-average molecular weight (polystyrene equivalent) of the acrylic resin is preferably 5,000 to 5,000,000, more preferably 10,000 to 2,000,000, and may also be 30,000 to 1,000,000 or 50,000 to 500,000. If the molecular weight of the acrylic resin is too low, the durability of the resulting film may decrease. If the molecular weight of the acrylic resin is too high, the film-forming properties may be poor.

From the viewpoint of thermal and photostability of the resin composition and molded article, it is preferable that the acrylic resin has a low content 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 even more preferably 5.08 g/100 g (0.2 mmol/g) or less. The iodine value of the acrylic resin may also 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 also be 0.1 mmol/g or less, 0.05 mmol/g or less, or 0.03 mmol/g or less. A low acid value enhances the stability of acrylic resins and tends to improve their compatibility with polyimides.

<Preparation of resin composition>
A resin composition is prepared by mixing the above-mentioned polyimide with an acrylic resin. The ratio of polyimide to acrylic resin in the resin composition is not particularly limited. The mixing ratio (by weight) of polyimide to acrylic resin may be 98:2 to 2:98, 95:5 to 10:90, or 90:10 to 15:85. The higher the proportion of polyimide, the higher the mechanical strength of the molded article, such as a film. The higher the proportion of acrylic resin, the less coloration the molded article, such as a film, tends to have, and the higher the transparency.

To fully realize the effect of improving transparency through mixing polyimide and acrylic resin, the ratio of acrylic resin to the total amount of polyimide and acrylic resin is preferably 10% by weight or more, and may also 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, or 50% by weight or more.

Polyimide is a polymer with a special molecular structure and generally exhibits low solubility in organic solvents and poor compatibility with other polymers. In this embodiment, by using a specific polyimide, high solubility in organic solvents and compatibility with acrylic resins are achieved. Whether polyimide and acrylic resin are compatible is confirmed by dissolving the resin composition in dimethylformamide (DMF) to a solid content concentration of 10% by weight. If the DMF solution is transparent and does not undergo phase separation, it is determined that the polyimide and acrylic resin are compatible in the resin composition. If the DMF solution separates into two or more phases or is cloudy, it is determined that the polyimide and acrylic resin are not compatible. The haze of the solution containing polyimide and acrylic resin, measured at a path length of 1 cm, is preferably 10% or less, more preferably 5% or less, even more preferably 2% or less, and particularly preferably 1% or less.

Resin compositions containing polyimide and acrylic resins preferably have a single glass transition temperature in suggested scanning calorimetry (DSC) and/or dynamic viscoelasticity measurement (DMA). When a resin composition has a single glass transition temperature, the polyimide and acrylic resin can be considered to be perfectly miscible. Molded articles containing polyimide and acrylic resins also preferably have a single glass transition temperature.

As mentioned above, polyimides exhibit compatibility with acrylic resins due to the presence of fluoroalkyl groups in their diamine-derived and/or acid dianhydride-derived structures. Whether or not a polyimide exhibits compatibility with an acrylic resin depends on the type and content of the fluoroalkyl group-containing monomer, the types and content of other monomers, and the type of acrylic resin.

The solubility parameter (SP value) can be used as an indicator to predict whether polyimide and acrylic resins are compatible. The SP value of a polymer is calculated using the Fedors method (atomic group contribution method). The Fedors method assumes that both the cohesive energy density E _coh and the molecular volume V depend on the type and number of atomic groups, and calculates the solubility parameter δ as δ = [ΣE _coh / ΣV] ^1/2 . If the molecular structure of the polymer is known, the SP value can be estimated relatively easily.

The smaller the difference in SP values between polyimide and the solvent and acrylic resin, the higher the solubility and compatibility tend to be. The SP value of polymethyl methacrylate calculated by the Fedors method is 20.15 (J/ ^cm³ ) ^1/2 , and the SP value tends to increase when a glutarimide structure is introduced. For example, the SP value of glutarimide-modified polymethyl methacrylate with a glutarimide content of 30% by weight is 20.9 (J/ ^cm³ ) ^1/2 .

Generally, polyimide has a higher SP value than acrylic resin. Therefore, the smaller the SP value of polyimide, the better its compatibility with acrylic resin tends to be. From the viewpoint of compatibility with acrylic resin, the SP value of polyimide is preferably 25.0 (J/ ^cm³ ) ^1/2 or less, more preferably 24.0 (J/ ^cm³ ) ^1/2 or less, and even more preferably 23.2 (J/ ^cm³ ) ^1/2 .

On the other hand, the SP value of DMF is 24.6 (J/ ^cm³ ) ^1/2 , and if the SP value of polyimide is small, its solubility in DMF decreases, which may result in low compatibility with acrylic resins in DMF. From the viewpoint of compatibility with acrylic resins in DMF, the SP value of polyimide is preferably 22.0 (J/ ^cm³ ) ^1/2 or higher, more preferably 22.1 (J/ ^cm³ ) ^1/2 or higher, and even more preferably 22.18 (J/ ^cm³ ) ^1/2 or higher.

The resin composition may simply be a mixture of polyimide and acrylic resin precipitated as solid components, or it may be a mixture of polyimide and acrylic resin. Alternatively, when precipitating the polyimide resin by mixing the polyimide solution with a poor solvent, the acrylic resin may be mixed into the solution, resulting in the precipitation of a resin composition containing both polyimide and acrylic resin as a solid (powder).

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

Examples of solvents for solutions containing polyimide and acrylic resins include DMF. As described above, the resin composition of this embodiment exhibits compatibility in DMF. The solvent is not limited to DMF, as long as it is soluble in both polyimide and acrylic resins. Examples include amide solvents such as N,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 propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and alkyl halogen solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and dichloromethane.

The resin composition may contain organic or inorganic low-molecular-weight compounds, high-molecular-weight compounds (e.g., epoxy resins), etc. The resin composition may also contain flame retardants, UV absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, fine particles, sensitizers, etc. Fine particles may include organic fine particles such as polystyrene and polytetrafluoroethylene, and inorganic fine particles such as colloidal silica, carbon, and layered silicates, and may have a porous or hollow structure. Fiber reinforcing materials may include carbon fibers, glass fibers, aramid fibers, etc.

[Molded articles and films]
The above composition can be used to form various molded articles. Molding methods include injection molding, transfer molding, press molding, blow molding, inflation molding, calendering, and melt extrusion. Resin compositions containing polyimide and acrylic resins tend to have a lower melt viscosity than polyimide alone and exhibit excellent moldability in injection molding, transfer molding, press molding, and melt extrusion.

Furthermore, solutions of resin compositions containing polyimide and acrylic resins tend to have lower viscosity than solutions of polyimide alone at the same solid content concentration. Therefore, they offer superior handling advantages, such as easier transport, higher coating properties, and are advantageous in reducing film thickness variations.

In one embodiment, the molded body is a film. The film can be formed by either a melting method or a solution method, but the solution method is preferred from the viewpoint of producing a film with excellent transparency and uniformity. In the solution method, a film is obtained by coating a solution containing the above-mentioned polyimide and acrylic resin onto a support and drying off the solvent.

As a method for applying the resin solution onto the support, known methods using bar coaters, comma coaters, etc., can be applied. As the support, glass substrates, metal substrates such as SUS, metal drums, metal belts, plastic films, etc., can be used. From the viewpoint of improving productivity, it is preferable to use an endless support such as a metal drum or metal belt, or a long plastic film, and manufacture the film by roll-to-roll. When using a plastic film as the support, a material that does not dissolve in the film-forming doping solvent should be appropriately selected.

Heating is preferable during solvent drying. The heating temperature is not particularly limited as long as it can remove the solvent and suppress discoloration of the resulting film; it can be appropriately set between room temperature and approximately 250°C, with 50°C to 220°C being preferred. The heating temperature may be increased in stages. To improve the efficiency of solvent removal, the resin film may be peeled from the support and dried after a certain degree of drying has occurred. Heating under reduced pressure may be performed to accelerate solvent removal.

Acrylic films may have low toughness, but their strength can be improved by using a compatible system of polyimide and acrylic resin. Stretching in one or more directions may be performed to improve the mechanical strength of the film. Stretching the film causes the polymer chains to orient in the stretching direction, improving the in-plane strength and tending to suppress cracking and fracture.

In particular, in compatible systems of polyimide and acrylic resins, the tensile modulus in the stretching direction increases, and consequently, the flexibility tends to improve. The higher the proportion of methyl methacrylate in the monomer components of the acrylic resin, the more pronounced the increase in the tensile modulus in the stretching direction becomes.

For example, films used as cover films or substrate materials for foldable displays require high mechanical strength in the direction perpendicular to the bending axis, as they are repeatedly folded along the same bending axis at the same point. Therefore, by arranging the film's stretching direction perpendicular to the bending axis, cracks and fractures are less likely to occur at the bending point even after repeated folding, providing a device with high bending resistance.

The stretching conditions for the film are not particularly limited. For example, the stretching temperature is approximately ±40°C of the film's glass transition temperature, and may be around 120-300°C, 150-250°C, or 180-230°C. The stretching ratio is approximately 1-200%, and may be 5-150%, 10-120%, or 20-100%. A larger stretching ratio tends to result in a higher tensile modulus in the stretching direction. On the other hand, if the stretching ratio is excessively high, the mechanical strength in the direction perpendicular to the stretching direction tends to decrease, which may reduce the film's handling properties.

From the viewpoint of increasing strength in any direction within the plane, the film may be biaxially stretched. Biaxial stretching may be simultaneous or sequential. In biaxial stretching, the stretching ratio in one direction and the stretching ratio in the direction perpendicular to it may be the same or different. When there is a difference in stretching ratios, the mechanical strength tends to be relatively higher in the direction with the larger stretching ratio. When using a biaxially oriented film with anisotropic stretching ratios in a foldable device, it is preferable to position the direction with the larger stretching ratio perpendicular to the folding axis.

The film thickness is not particularly limited and can be set appropriately according to the application. For example, the film thickness is 5 to 300 μm. From the viewpoint of achieving both self-supporting properties and flexibility, and high transparency, the film thickness is preferably 20 μm to 200 μm, and may also be 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 80 μm. For use as a cover film for displays, a film thickness of 10 μm or more is preferred. When stretching the film, it is preferable that the thickness after stretching is within the above range.

The haze of the film is preferably 10% or less, more preferably 5% or less, even more preferably 4% or less, and may also be 3.5% or less, 3% or less, 2% or less, or 1% or less. A lower haze is preferable. As described above, because 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 with a thickness of 10 μm is produced.

The total light transmittance of the film is preferably 85% or higher, and preferably 90% or higher. The resin composition, obtained by mixing polyimide and acrylic resin, preferably has a total light transmittance of 85% or higher when a film with a thickness of 10 μm is produced.

The yellowness (YI) of the film is preferably 5.0 or less, but may also be 4.0 or less, 3.0 or less, 2.0 or less, 1.5 or less, or 1.0 or less. The resin composition obtained by mixing polyimide and acrylic resin preferably has a yellowness of 5.0 or less when a film with a thickness of 10 μm is produced. As described above, by mixing polyimide and acrylic resin, a film with less coloration and a lower YI can be obtained compared to when polyimide is used alone.

From the viewpoint of strength, the tensile modulus of the film is preferably 3.5 GPa or higher, and may be 4.0 GPa or higher. As described above, the tensile modulus may be anisotropic, and the tensile modulus in at least one direction may be 4.5 GPa or higher, 5.0 GPa or higher, 5.5 GPa or higher, 6.0 GPa or higher, 6.5 GPa or higher, or 7.0 GPa or higher. The pencil hardness of the film 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 does not easily decrease even if the ratio of acrylic resin is increased. Therefore, it is possible to provide a film with less coloration and excellent transparency without significantly reducing the excellent mechanical strength characteristic of polyimide.

Films formed from resin compositions containing polyimide and acrylic resins are suitable for use as display materials due to their low coloration and high transparency. In particular, films with high mechanical strength can be applied to surface components such as display cover windows. For practical use, the film of the present invention may be provided with an antistatic layer, an easy-adhesion layer, a hard coat layer, an anti-reflective layer, etc., on its surface.

The embodiments of the present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following embodiments.

[Preparation of polyimide resin]
Dimethylformamide (hereinafter referred to as DMF) was placed in a separable flask and stirred under a nitrogen atmosphere. Diamine and tetracarboxylic dianhydride were then added 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 obtain a polyamic acid solution with a solid content of 18% by weight. Pyridine was added to the polyamic acid solution as an imidization catalyst and dispersed completely, then acetic anhydride was added and the mixture was stirred at 90°C for 3 hours. After cooling to room temperature, 2-propyl alcohol (hereinafter referred to as IPA) was added dropwise while stirring the solution to precipitate the polyimide resin. Further IPA was added and stirred for about 30 minutes, then suction filtration was performed using a Kiriyama funnel. The obtained solid was washed with IPA and dried in a vacuum oven set to 120°C for 12 hours to obtain polyimide resins 1 to 46. Note that polyimide resin 42, which uses BTBA as the diamine, has an amide bond and therefore belongs to the polyamide-imide category, but is described here as a polyimide resin.

[Preparation of polyamide-imide resin]
Diamine, tetracarboxylic dianhydride, and dicarboxylic acid dichloride were added in the proportions (mol%) shown in Table 3. Otherwise, polymerization (preparation of polyamic acid solution), imidization, resin precipitation, washing, and drying were carried out in the same manner as for the preparation of polyimide resin to obtain polyamide-imide resins 101 to 113.

[Preparation of polyamide resin]
Diamine (TFMB) and dicarboxylic acid dichlorides (TPC and IPC) were added to DMF in the ratios (mol%) shown in Table 3 and reacted under a nitrogen atmosphere to obtain a polyamide solution. IPA was added dropwise to this solution to precipitate the polyamide resin. Subsequently, washing and drying were performed in the same manner as for the preparation of polyimide resin to obtain polyamide resin 114.

[Calculation of solubility parameters]
The solubility parameter (SP) was calculated for the resin prepared above using the Fedors method. The calculation was performed using BIOVIA Notebook and BIOVIA Pipeline Pilot Polymer Properties. Specifically, the protocol shown in Figure 1 was created in BIOVIA Pipeline Pilot Polymer Properties, and this protocol was retrieved from BIOVIA Notebook to calculate the solubility parameter based on the structure after the polymerization and imidization reactions had completely proceeded. For example, for polyimide resin 2 (TFMB//6FDA/CBDA = 100//95/5), the calculation was performed for a polymer having the following structures X1 to X3 in a ratio of X1:X2:X3 = 0.5:0.475:0.025. The calculations for polyimide resin 101 (TFMB//6FDA/TPC = 100//70/30) were performed for a polymer having the following structures X1, X2, and X4 in the ratio X1:X2:X4 = 0.5:0.35:0.15.

[Preparation of resin composition (solution) and production of film]
<Resin composition of polyimide and PMMA>
A DMF solution with a solid content of 10% by weight was prepared by adding the above-mentioned resin and a commercially available polymethyl methacrylate resin (Kuraray's "Parapet HM1000", glass transition temperature: 120°C, hereinafter referred to as "Acrylic 1") in a weight ratio of 50:50 to DMF.

The above solution was applied to an alkali-free glass plate and heated and dried in an atmospheric environment to produce a film approximately 10 μm thick. The film was peeled from the glass plate, cut into 3 cm squares, and the haze was measured using a Suga Test Instruments HZ-V3 haze meter according to JIS K7136. A haze of less than 5% was marked with a circle (○), and a haze exceeding 5% was marked with a cross (×).

<Resin composition of polyimide and glutarimide-modified acrylic resin>
Instead of Acrylic 1, a glutarimide-modified acrylic resin (hereinafter referred to as "Acrylic 2") with a glutarimide content of 33% by weight and a glass transition temperature of 131°C, prepared according to "Acrylic Resin Production Example 3" of Japanese Patent Application Publication No. 2018-70710, was used. The DMF solution was prepared and a film was made in the same manner as described above, and the haze of the film was measured.

[Evaluation Results]
Tables 1 to 3 show the composition and SP value of the polyimide, as well as the evaluation results of the transparency of films made from mixed resin compositions with acrylic resin.

In Tables 1-3, the compounds are indicated by the following abbreviations.
<Diamine>
TFMB: 2,2'-bis(trifluoromethyl)benzidine HFBAAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane BAFL: 9,9-bis(4-aminophenyl)fluorene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane m-PDA: m-phenylenediamine m-XDA: m-xylenediamine 33DDS: 3,3'-diaminodiphenylsulfone 14CHDA: 1,4-cyclohexanediamine 13CHDA: 1,3-cyclohexanediamine BAMC: 1,3-bis(aminomethyl)cyclohexane BAMN: bis(aminomethyl)norbornane ISO: Isophoronediamine BTBA: Condensate of TFMB and TPC represented by the following formula (4)

<Tetracarboxylic acid dianhydride>
6FDA: 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride PMDA: pyromellitic anhydride ODPA: 4,4'-oxydiphthalic acid dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride a-BPDA: 2,3,3',4'-biphenyltetracarboxylic acid dianhydride BTDA: 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride TMHQ: p-phenylenebis(trimellitic acid monoester acid anhydride)
BP-TME: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'diyl BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride TAHMBP: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'diyl CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride H-PMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride H-BPDA: 1,1'-bicyclohexane-3,3',4,4'tetracarboxylic acid-3,4:3',4'-dianhydride 22BZ: 4,4'-diamino-2,2'-dimethylbiphenyl

<Dicarboxylic acid dichloride>
TPC: Terephthalic acid dichloride IPC: Isophthalic acid dichloride H-TPC: 1,4-Cyclohexanedicarboxylic acid dichloride BPC: 4,4'-Biphenyldicarboxylic acid dichloride OBC: 4,4'-Oxybis(benzoyl chloride)

The results above indicate that polyimides with specific structures exhibit compatibility with acrylic resins, making it possible to produce low-haze films.

Claims (15)

A resin composition comprising polyimide and an acrylic resin,
The polyimide has a structure derived from a diamine represented by general formula (IIa) and a structure derived from a tetracarboxylic dianhydride represented by general formula (IIIa).
Y is a divalent organic group, a diamine residue, and X is a tetravalent organic group, a tetracarboxylic dianhydride residue.
The polyimide satisfies at least one of the following (A) and (B):
(A) The ratio of structures derived from diamines having fluoroalkyl groups to the total amount of the diamine-derived structures is 70 mol% or more;
(B) The ratio of the structure derived from the tetracarboxylic dianhydride having a fluoroalkyl group to the total amount of the structure derived from the tetracarboxylic dianhydride is 70 mol% or more.
The aforementioned acrylic resin is polymethyl methacrylate or polymethyl methacrylate having a glutarimide structure.
The polyimide and the acrylic resin are contained in a weight ratio in the range of 98:2 to 2:98.
A resin composition in which the polyimide and the acrylic resin are compatible in dimethylformamide. The resin composition according to claim 1 , wherein the polyimide satisfies (A) . The resin composition according to claim 2, wherein the diamine having a fluoroalkyl group comprises a fluoroalkyl-substituted benzidine. The resin composition according to claim 3, wherein the fluoroalkyl-substituted benzidine is 2,2'-bis(trifluoromethyl)benzidine. The resin composition according to claim 2, wherein the polyimide comprises one or more structures selected from the group consisting of a structure derived from a tetracarboxylic dianhydride having a fluoroalkyl group, a bis(trimellitic anhydride) ester, and a structure derived from a tetracarboxylic dianhydride having an ether structure, as the tetracarboxylic dianhydride-derived structure. The resin composition according to claim 5 , wherein the tetracarboxylic dianhydride having the fluoroalkyl group comprises 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride. The resin composition according to claim 5 , wherein the bis(trimellitic anhydride) ester comprises a compound represented by formula (3).
The resin composition according to claim 5, wherein the polyimide has a total ratio of 40 mol% or more of the structure derived from the tetracarboxylic dianhydride having a fluoroalkyl group, the structure derived from the bis(trimellitic anhydride) ester , and the structure derived from the tetracarboxylic dianhydride having an ether structure , relative to the total amount of the structure derived from the tetracarboxylic dianhydride. The resin composition according to claim 1, wherein the polyimide satisfies (B). The resin composition according to claim 9 , wherein the tetracarboxylic dianhydride having the fluoroalkyl group comprises 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride. The polyimide further comprises a dicarboxylic acid-derived structure represented by the general formula (Va),
Z is a divalent organic group, a dicarboxylic acid residue.
The resin composition according to any one of claims 1 to 10 . The resin composition according to any one of claims 1 to 10 , wherein the solubility parameter of the polyimide calculated by the Fedors method is 21.8 to 23.2. A molded article comprising the resin composition according to any one of claims 1 to 10 . A film comprising the resin composition according to any one of claims 1 to 10 . The film according to claim 14, wherein the total light transmittance is 85% or more, the haze is 10% or less, and the yellowness is 5.0 or less.