Polyamide-imide, resin composition, molded article, and film

Abstract

The present invention relates to a polyamideimide, and a resin composition comprising a polyamideimide and an acrylic resin. The polyamide-imide has a diamine component, a tetracarboxylic acid dianhydride component, and a polybasic acid component, and contains, as the diamine component, a diamine having one or more structures selected from the group consisting of CF3-O-,-(CF2-O) n-, and-O-(CF2-CF2-O) n-(where n is an integer of 1-20), and preferably, as the diamine, 2, 2 '-bis (trifluoromethoxy) benzidine, 3, 3'-bis (trifluoromethoxy) benzidine, or 2, 3 '-bis (trifluoromethoxy) benzidine. And 3, 3 '-bis (trifluoromethoxy) benzidine and the like.

Description

Polyamide-imide, resin composition, molded article and film Technical Field

[0001] The present invention relates to polyamide-imide, resin compositions comprising the polyamide-imide, and molded articles such as films. Background Technology

[0002] Thinness, lightweight, and flexibility are required in display devices such as liquid crystal displays (LCDs), organic EL displays, and electronic paper, as well as in electronic devices such as solar cells and touch panels. These properties can be achieved by replacing the glass materials used in these devices with thin-film materials. Transparent polyimide films have been developed as glass alternatives and are used in display substrates and cover films. Patent Document 1 proposes a method using polyamide-imide as a cover film material for flexible displays.

[0003] As a method for manufacturing highly transparent polyamide-imide films, a method has been proposed that uses a polyamide-imide resin soluble in organic solvents and requiring no high-temperature imidization after film formation. From the viewpoint of achieving a balance between transparency and mechanical properties, such soluble polyamide-imides use fluorinated compounds as the diamine and / or tetracarboxylic dianhydride belonging to the monomer. For example, the polyamide-imide in Patent Document 1 uses 2,2'-bis(trifluoromethyl)benzidine (TFMB) as the diamine and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) as the tetracarboxylic dianhydride.

[0004] Patent document 2 describes a method for improving the transparency of a film by mixing soluble polyamide-imide with an acrylic resin.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2013 / 048126

[0008] Patent Document 2: International Publication No. 2023 / 132310 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In recent years, the environmental residues of organofluorine compounds (PFAS) have become a concern. Typically, the carbon-fluorine bonds in PFAS have high bond energies, making them difficult to break down in the environment. In particular, PFAS containing structures with trifluoromethyl groups bonded to carbon atoms (-C-CF3) or structures with carbon atoms bonded to both ends of difluoromethylene groups (-C-CF2-C-) have low environmental decomposition rates and have been identified as having potential health effects.

[0011] In view of the above-mentioned issues, the object of the present invention is to provide a polyamide-imide with excellent environmental safety, solubility in organic solvents, and excellent transparency, a resin composition comprising the polyamide-imide, and molded articles such as films.

[0012] Solution for solving the problem

[0013] This invention relates to polyamide-imides and resin compositions comprising polyamide-imides and acrylic resins. The polyamide-imides contain components selected from CF3-O- and -(CF2-O). n - and -O- (CF2-CF2-O) n - A diamine containing one or more fluorine atoms (a specific diamine) as the diamine component. - (CF2-O) n - and -O- (CF2-CF2-O) n In the -, n is an integer from 1 to 20.

[0014] Preferred examples of specific diamines that are diamines containing fluorine atoms include 2,2'-bis(trifluoromethoxy)benzidine, 3,3'-bis(trifluoromethoxy)benzidine and 2,3'-bis(trifluoromethoxy)benzidine.

[0015] The polyamide imide preferably contains one or more tetracarboxylic dianhydrides (specific acid dianhydrides) selected from the group consisting of tetracarboxylic dianhydrides having ether bonds, tetracarboxylic dianhydrides having fluorene structures, tetracarboxylic dianhydrides having xanthine structures, and bis(triphenyl esters) esters as the tetracarboxylic dianhydride component.

[0016] Preferred examples of specific acid dianhydrides include 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 3,4'-oxodiphthalic anhydride, 4,4'-oxodiphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 5,5'-(9H-fluorene-9-idene bis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate], spiro[fluorene-9,9'-xanthine]-2 ',3',6',7'-tetracarboxylic acid dianhydride, 5,5'-spiro[9H-fluorene-9,9'-[9H]xanton]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylic acid ester), p-phenylenebis(trimethicone monoester anhydride), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-dimethyl ester and bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-dimethyl ester.

[0017] Polyamide imide may contain a diamine other than a specific diamine as a diamine component, or it may contain a tetracarboxylic dianhydride other than a specific acid dianhydride as a tetracarboxylic dianhydride component.

[0018] Examples of tetracarboxylic dianhydrides other than specific acid dianhydrides include 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 1,2,3,4-phenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride.

[0019] Tetracarboxylic dianhydrides, other than specific acid dianhydrides, can also be alicyclic tetracarboxylic dianhydrides. Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, and 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydride. The amount of alicyclic tetracarboxylic dianhydride can be 1 to 80 mol relative to the total amount of tetracarboxylic dianhydride in the polyamide imide.

[0020] For polyamide imide, preferably, the amount of diamine having a structure in which CF3- or -C(CF3)2- is directly bonded to the carbon atom of the aromatic ring is less than 0.5 mol% relative to the total amount of diamine component, and the amount of tetracarboxylic dianhydride having a structure in which CF3- or -C(CF3)2- is directly bonded to the carbon atom of the aromatic ring is less than 0.5 mol% relative to the total amount of tetracarboxylic dianhydride component.

[0021] Polyamide-imide is preferably soluble in dimethylformamide at 23°C.

[0022] The resin composition of the present invention comprises the above-described polyamide and acrylic resin. The resin composition may comprise polyamide-imide and acrylic resin in a weight ratio ranging from 98:2 to 2:98.

[0023] The above-mentioned polyamide-imide and resin composition can be applied to molded articles such as films.

[0024] The effects of the invention

[0025] Polyamide-imides containing a specific diamine as a diamine component exhibit excellent solubility and transparency in organic solvents. Furthermore, compared to organofluorine compounds such as fluoroalkyl-substituted benzidines, the specific diamine has lower environmental residue, thus the polyamide-imide of this invention demonstrates excellent environmental safety. Detailed Implementation

[0026] [Polyamide imide]

[0027] Polyamide imide is a polymer having an imide structural unit as shown in general formula (I), an amide structural unit as shown in general formula (II), and / or an amide imide structural unit as shown in general formula (III).

[0028]

[0029] In general formulas (I) to (III), X is a tetravalent organic group, Y and Z are divalent organic groups, and W is a trivalent organic group. Y is a diamine residue, which is an organic group obtained by removing two amino groups from the diamine shown in general formula (V). X is a tetracarboxylic dianhydride (hereinafter sometimes referred to as "acid dianhydride") residue, which is an organic group obtained by removing two carboxyl anhydrides from the tetracarboxylic dianhydride shown in general formula (IV). Z is a dicarboxylic acid residue, which is an organic group obtained by removing two carboxyl groups from the dicarboxylic acid shown in general formula (VI). W is a tricarboxylic acid anhydride residue, which is an organic group obtained by removing the carboxyl anhydride and carboxyl groups from the tricarboxylic acid anhydride shown in general formula (VII).

[0030]

[0031] In other words, polyamide-imide comprises a structure derived from a diamine as shown in general formula (Va) and a structure derived from a tetracarboxylic dianhydride as shown in general formula (IVa), and further comprises one or more structures selected from the group consisting of a structure derived from a dicarboxylic acid as shown in general formula (VIa) and a structure derived from a tricarboxylic anhydride as shown in general formula (VIIa). An imide structural unit of general formula (I) is formed by forming an imide bond between the structure derived from a diamine (Va) and the structure derived from a tetracarboxylic dianhydride (IVa); an amide structural unit of general formula (II) is formed by forming an amide bond between the structure derived from a diamine (Va) and the structure derived from a dicarboxylic acid (VIa); and an amide-imide structural unit of general formula (III) is formed by forming an imide bond and an amide bond between the carboxyl anhydride portion and the carboxyl portion of the structure derived from a tricarboxylic anhydride (VIIa) and the structure derived from a diamine (Va), respectively.

[0032]

[0033] Polyamide imide can contain a variety of diamine residues Y, a variety of tetracarboxylic acid dianhydride residues X, a variety of dicarboxylic acid residues Z, and a variety of tricarboxylic acid dianhydride residues W.

[0034] As described below, polyamide-imides are typically obtained as follows: polyamic acid is synthesized from polyacid derivatives such as diamines, tetracarboxylic dianhydrides, dicarboxylic dianhydrides, and tricarboxylic anhydride acyl chlorides as monomers; and the amic acid at the bonded portion of the tetracarboxylic or tricarboxylic acid to the diamine is dehydrated and cyclized to obtain the polyamide-imide. Polyacid derivatives such as dicarboxylic dianhydrides and tricarboxylic anhydride acyl chlorides can be used as starting materials, but the resulting polyamide-imide has a structure Z (dicarboxylic acid residue) formed by removing two carboxyl groups from a dicarboxylic acid or a structure W formed by removing three carboxyl groups from a tricarboxylic acid. Regardless of the type of starting material (monomer) used in the synthesis of polyamide-imides, the structure corresponding to tetracarboxylic dianhydride residue X in the polyamide-imide is described as the "tetracarboxylic dianhydride component," the structure corresponding to diamine residue Y is described as the "diamine component," and the structure corresponding to dicarboxylic acid residue Z and the structure corresponding to tricarboxylic anhydride residue W are described as the "polyacid component."

[0035] The following examples illustrate the diamine, tetracarboxylic acid dianhydride, and polybasic acid components that constitute polyamide-imide monomers.

[0036] <Diamine>

[0037] (Specific diamine)

[0038] The polyamide-imide of the present invention comprises having a composition selected from CF3-O-, -(CF2-O). n - and -O- (CF2-CF2-O) n - One or more diamines with the specified structure are designated as diamine components. n is an integer from 1 to 20. Hereinafter, these diamines will be referred to as "specific diamines".

[0039] In certain diamines, the carbon atoms of the trifluoromethyl group (-CF3) or the difluoromethylene group (-CF2-) are bonded to oxygen atoms. Compared to structures where the trifluoromethyl group is bonded to a carbon atom (-C-CF3) or where carbon atoms are bonded to both ends of the difluoromethylene group (-C-CF2-C-), these diamines tend to have higher decomposability and lower environmental residue. Therefore, polyamide-imides containing specific diamines as diamine components exhibit superior environmental safety compared to conventional soluble polyamide-imides containing organofluorine compounds such as fluoroalkyl-substituted benzidines as diamine components.

[0040] Among specific diamines, from the perspective of not belonging to the "specific fluorine structure" described later, it is preferable to have CF3-O- or -(CF2-O). nFrom the viewpoint of the polymerizability and mechanical strength of polyamide-imide, diamines having a trifluoromethoxy group (CF3-O-) are preferred, wherein the oxygen atom of the trifluoromethoxy group is preferably bonded to a carbon atom of the aromatic ring. From the viewpoint of reactivity, diamines with the trifluoromethoxy group bonded to a carbon atom of the aromatic ring preferably do not have a fluorine atom directly bonded to the aromatic ring to which the trifluoromethoxy group is bonded, and are particularly preferred to not contain any fluorine atoms other than the trifluoromethoxy group. Examples of specific diamines with the trifluoromethoxy group bonded to a carbon atom of the aromatic ring include trifluoromethoxy-substituted benzidine and trifluoromethoxy-substituted phenylenediamine.

[0041] Examples of trifluoromethoxy-substituted benzidines include 2-(trifluoromethoxy)benzidine, 3-(trifluoromethoxy)benzidine, 2,3-bis(trifluoromethoxy)benzidine, 2,5-bis(trifluoromethoxy)benzidine, 2,6-bis(trifluoromethoxy)benzidine, 2,3,5-tris(trifluoromethoxy)benzidine, 2,3,6-tris(trifluoromethoxy)benzidine, 2,3,5,6-tetra(trifluoromethoxy)benzidine, 2,2'-bis(trifluoromethoxy)benzidine (TFMOB), 3,3'-bis(trifluoromethoxy)benzidine, and 2,3 '-bis(trifluoromethoxy)benzidine, 2,2',3-tris(trifluoromethoxy)benzidine, 2,3,3'-tris(trifluoromethoxy)benzidine, 2,2',5-tris(trifluoromethoxy)benzidine, 2,2',6-tris(trifluoromethoxy)benzidine, 2,3',5-tris(trifluoromethoxy)benzidine, 2,3',6-tris(trifluoromethoxy)benzidine, 2,2',3,3'-tetra(trifluoromethoxy)benzidine, 2,2',5,5'-tetra(trifluoromethoxy)benzidine, 2,2',6,6'-tetra(trifluoromethoxy)benzidine, etc.

[0042] Examples of trifluoromethoxy-substituted phenylenediamines include 1,2-diamino-4-(trifluoromethoxy)benzene, 1,3-diamino-4-(trifluoromethoxy)benzene, 1,4-diamino-2-(trifluoromethoxy)benzene, 1,4-diamino-2,3-bis(trifluoromethoxy)benzene, 1,4-diamino-2,5-bis(trifluoromethoxy)benzene, 1,4-diamino-2,6-bis(trifluoromethoxy)benzene, 1,4-diamino-2,3,5-tris(trifluoromethoxy)benzene, and 1,4-diamino-2,3,5,6-tetra(trifluoromethoxy)benzene.

[0043] From the viewpoint of the polymerizability and mechanical strength of polyamide-imide, trifluoromethoxy-substituted benzidine is preferred as a specific diamine. Specifically, from the viewpoint of the solubility of the polyamide-imide resin in organic solvents and its compatibility with other resins, the presence of a trifluoromethoxy group at the 2 or 3 position of biphenyl is preferred, more preferably 2,2'-bis(trifluoromethoxy)benzidine (hereinafter referred to as "TFMOB"), 3,3'-bis(trifluoromethoxy)benzidine, and 2,3'-bis(trifluoromethoxy)benzidine, with TFMOB being particularly preferred. By having a trifluoromethoxy group at the 2 or 3 position of biphenyl, in addition to the reduction in π-electron density caused by the electron-withdrawing property of the trifluoromethoxy group, the steric hindrance of the trifluoromethoxy group also hinders the π-π stacking of the benzene rings, resulting in a short wavelength shift at the absorption end, which can reduce the coloration of the polyamide-imide. In addition, due to the steric hindrance of the trifluoromethoxy groups at the 2 and 2' positions of biphenyl, the bond between the two benzene rings of biphenyl is twisted, and the planarity of π-conjugation is reduced. Therefore, the absorption wavelength undergoes a short wavelength shift, which can reduce the coloring of polyamide imide.

[0044] The amount of a specific diamine relative to the total amount of diamine is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and can be 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more, or even 100 mol%. This range is particularly preferred for the amount of trifluoromethoxy-containing diamine, and especially preferred for the amount of trifluoromethoxy-substituted benzidine. A higher ratio of the specific diamine helps suppress coloration, and sometimes improves the mechanical strength of the film, such as pencil hardness, elastic modulus, tensile strength, and elongation at break.

[0045] (Diamines other than certain diamines)

[0046] Polyamide-imides may contain diamines other than specific diamines as diamine components. From the viewpoint of the environmental safety of polyamide-imides, it is preferable that they do not contain -C-CF3 and -C-CF2-C-, and particularly preferable that they do not contain fluorine atoms.

[0047] Examples of diamines that do not contain fluorine atoms include 2,2'-dimethylbenzidine, 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'-diaminodiphenyl sulfone, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 3,3'-diaminobenzophenone, and 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-dimethylbenzene), 1,3-bis(4-amino-α,α-dimethylbenzene), 1,4-bis(3-amino-α,α-dimethylbenzene), 1,4-bis(4-amino-α,α-dimethylbenzene), 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]one, bis[4-(4-aminophenoxy)phenyl]one, 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]diphenyl sulfone, 4,4'-bis[4-( 4-Aminophenoxy)phenoxy]diphenyl sulfone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4,4'-diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α,ω - bis(3-aminobutyl)polydimethylsiloxane, bis(aminomethyl) ether, bis(2-aminoethyl) ether, bis(3-aminopropyl) ether, bis(2-aminomethoxy)ethyl] ether, bis[2-(2-aminoethoxy)ethyl] ether, bis[2-(3-aminopropoxy)ethyl] ether, 1,2-bis(aminomethoxy)ethane, 1,2-bis(2-aminoethoxy)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-aminocyclohexyl)methane, isophorone diamine, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, etc.

[0048] As a diamine, in addition to specific diamines, the solubility and transparency of polyamide-imide resins can sometimes be improved by using diaminodiphenyl sulfone. Among diaminodiphenyl sulfones, 3,3'-diaminodiphenyl sulfone (3,3'-DDS) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS) are preferred, and they can also be used in combination.

[0049] When diaminodiphenyl sulfone is used in addition to a specific diamine, the amount of diaminodiphenyl sulfone may be 1 to 80 mol%, 3 to 60 mol%, or 5 to 30 mol relative to the total amount of diamine.

[0050] As diamines, in addition to specific diamines, the solubility, transparency, and mechanical strength of polyamide-imide resins are sometimes improved by using diamines with a fluorene structure. 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and 9,9-bis(4-amino-3-methylphenyl)fluorene are preferred as fluorene-containing diamines, and they can also be used in combination.

[0051] When a diamine with a fluorene structure is used in addition to a specific diamine, the amount of the diamine with a fluorene structure may be 1 to 80 mol%, 3 to 60 mol%, or 5 to 30 mol% relative to the total amount of diamine components.

[0052] As a diamine, in addition to certain diamines, the transparency of polyamide-imide is sometimes improved by using alicyclic diamines. Among alicyclic diamines, isophorone diamine and 1,4-diaminocyclohexane are preferred, and they can also be used in combination.

[0053] When alicyclic diamine is used in addition to a specific diamine, the amount of alicyclic diamine may be 1-70 mol%, 3-50 mol%, 5-40 mol%, 10-30 mol%, or 12-25 mol% relative to the total amount of diamine component.

[0054] The total amount of specific diamine, diaminodiphenyl sulfone, diamine having a fluorene structure and alicyclic diamine relative to the total amount of diamine component of polyamide imide 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 99 mol% or more, or may be 100 mol%.

[0055] Polyamide-imide may contain fluorine-containing diamines other than a specific diamine as its diamine component. However, from the viewpoint of the environmental safety of polyamide-imide, the amount of fluorine-containing diamines other than the specific diamine is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, and can be 5 mol% or less, 1 mol% or less, or 0.5 mol% or less. Polyamide-imide may also not contain fluorine-containing diamines other than the specific diamine as its diamine component.

[0056] Among fluorine-containing diamines, those with a trifluoromethyl group bonded to a carbon atom (-C-CF3) and / or a structure with carbon atoms bonded to both ends of a difluoromethylene group (-C-CF2-C-) have low decomposability, raising concerns about environmental safety. From the viewpoint of improving the transparency and solvent solubility of polyamide-imides, conventional soluble polyamide-imides typically include diamines with a structure having CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring (e.g., trifluoromethoxy-substituted benzidines such as 2,2'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane) as diamine components. However, from the viewpoint of the environmental safety of polyamide-imides, it is preferable to substantially exclude these diamines. Relative to the total amount of diamine components in polyamide-imide, the amount of diamines with CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring is preferably less than 0.5 mol%, and can be less than 0.3 mol%, less than 0.1 mol%, or less than 0.05 mol%, or even 0.

[0057] Tetracarboxylic dianhydride

[0058] (Specific acid dianhydrides)

[0059] The dianhydride component of polyamide-imide is not particularly limited. From the viewpoint of improving environmental safety and having solubility in organic solvents, it is preferable that the dianhydride component includes one or more acid dianhydrides selected from the group consisting of acid dianhydrides having ether bonds, bis(triphenylamine) esters, acid dianhydrides having fluorene structures, and acid dianhydrides having xanthones. Hereinafter, these acid dianhydrides will be referred to as "specific acid dianhydrides".

[0060] Examples of acid dianhydrides containing ether bonds include those formed by the bonding of two phthalic anhydrides via an ether bond (-O-) or a functional group containing an ether bond. Examples of acid dianhydrides formed by the bonding of two phthalic anhydrides via an ether bond include 3,4'-oxobisphthalic anhydride (a-ODPA) and 4,4'-oxobisphthalic anhydride (s-ODPA).

[0061] As a functional group containing an ether bond, bisphenol derivative structures can be cited. As an acid dianhydride formed by the bonding of two phthalic anhydrides via a bisphenol derivative structure, compounds represented by the following general formula (5) can be cited.

[0062]

[0063] In general formula (5), A is any divalent organic group, and p is 1 or 2. 1a R 1b R 2a and R 2b Each can be any substituent independently, m1 and m2 are each an integer from 0 to 3, and n1 and n2 are each an integer from 0 to 4.

[0064] Examples of divalent organic groups A include (a), (b), and (c) below. In (a), R... 3a and R 3b Each is independently a hydrogen atom or an alkyl or phenyl group having 1 to 10 carbon atoms. (b) R 4 For alkyl groups with 1 to 10 carbon atoms, k is an integer from 0 to 10. When k is 2 or higher, multiple R groups are considered. 4 They can be the same or different.

[0065]

[0066] As a substituent R 1a and R 1b and substituent R 2a and R 2b Examples include alkyl groups with 1 to 10 carbon atoms, alkoxy groups with 1 to 10 carbon atoms, phenyl groups, and halogens.

[0067] From the viewpoint of the solubility of polyamide-imide resins, the acid dianhydride with ether bonds is preferably the acid dianhydride shown in general formula (1), of which 4,4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride (BPADA) is particularly preferred.

[0068] The bis(triphenyltrihydride) ester is represented by the following general formula (1).

[0069]

[0070] In general formula (1), X is any divalent organic group, with carboxyl groups bonded to carbon atoms at both ends of X. The carbon atoms bonded to the carboxyl groups can form a ring structure. Specific examples of divalent organic groups X include (A) to (K) below.

[0071]

[0072] R in equation (A) 1 The group is an alkyl or fluorine atom with 1 to 20 carbon atoms, and m is an integer from 0 to 4. The group shown in formula (A) is obtained by removing two hydroxyl groups from hydroquinones that have optional substituents on the benzene ring. Examples of hydroquinone derivatives with substituents on the benzene ring include tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, and 2,5-di-tert-pentylhydroquinone.

[0073] R in equation (B) 2 The group is an alkyl or fluorine atom with 1 to 20 carbon atoms, and n is an integer from 0 to 4. The group shown in formula (B) is obtained by removing two hydroxyl groups from a biphenol that optionally has substituents on the benzene ring. Examples of biphenol derivatives with 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, 2,2',3,3', 5,5'-hexamethylbiphenyl-4,4'-diol, etc.

[0074] The group shown in formula (C) is obtained by removing two hydroxyl groups from 4,4'-isopropylidene diphenol (bisphenol A). The group shown in formula (D) is obtained by removing two hydroxyl groups from resorcinol.

[0075] In formula (E), p is an integer from 1 to 10. The group shown in formula (E) is obtained by removing two hydroxyl groups from a straight-chain diol with 1 to 10 carbon atoms. Examples of straight-chain diols with 1 to 10 carbon atoms include ethylene glycol and 1,4-butanediol.

[0076] The group shown in formula (F) is obtained by removing two hydroxyl groups from 1,4-cyclohexanediethanol.

[0077] R in equation (G) 3 The group is an alkyl group with 1 to 20 hydrogen atoms, fluorine atoms, and carbon atoms, and q is an integer from 0 to 4. The group shown in formula (G) is obtained by removing two hydroxyl groups from bisphenol fluorene, which has optional 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 X has the structure of formula (G), it is equivalent to both acid dianhydrides with a fluorene structure and bis(triphenyl anhydride) esters, but as a classification of specific acid dianhydrides, it is denoted as a bis(triphenyl anhydride) ester. In addition, X in formula (1) is a compound with the structure of formula (J), which is equivalent to any one of acid dianhydrides with a fluorene structure, acid dianhydrides with a thallium structure, and bis(triphenyl anhydride) esters, but as a classification of specific acid dianhydrides, it is denoted as a bis(triphenyl anhydride) ester.

[0078] The bis(triphenylamine) ester is preferably an aromatic ester. As X, among (A) to (K) above, (A), (B), (C), (D), (G), (H), and (I) are preferred. Among these, (A) to (D) are preferred, and (B) having a biphenyl skeleton is particularly preferred. When X is a group represented by general formula (B), from the viewpoint of the solubility of the polyamide-imide resin, X is preferably biphenylene or 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl as shown in formula (B1) below.

[0079]

[0080] In general formula (1), X is the dianhydride of a biphenylene group, which is bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-dimethyl ester. In general formula (1), X is the dianhydride of a group represented by formula (B1), which is bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-dimethyl ester (TAHMBP) as shown in formula (3).

[0081]

[0082] As X in general formula (1) is a bis(triphenyltrihydride) ester with a structure other than formula (B), preferably p-phenylene bis(triphenyltrihydride) monoester anhydride (TMHQ), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-diyl ester (OCBP-TME), 5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylic acid ester) (BP-TME), tert-butylhydroquinone bis(triphenyltrihydride) ester (TA.BHQ), and trimethylhydroquinone bis(triphenyltrihydride) ester (TA.TMHQ).

[0083] From the viewpoint of polyamide-imide solubility, TMHQ, THAHMBP, and OCBP-TME are particularly preferred as bis(triphenylamine) esters.

[0084] Examples of fluorene-containing dianhydrides include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA), N,N'-(9H-fluorene-9-idene di-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxamide] (FDA-ATA), and 5,5'-(9H-fluorene-9-idene di(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate] (TBIS.MPN). From the viewpoint of polyamide-imide solubility, BPAF, BPF-PA, or TBIS.MPN are preferred, with BPAF or BPF-PA being particularly preferred among these.

[0085] Examples of acid dianhydrides with a xanthonium structure include 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthonium]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate (TBIS.RXN) and spiro[fluorene-9,9'-xanthonium]-2',3',6',7'-tetracarboxylic acid dianhydride (SFDA). These example compounds contain both xanthonium and fluorene structures, but are referred to as acid dianhydrides with a xanthonium structure as a specific classification of acid dianhydrides.

[0086] Polyamide-imides containing the aforementioned specific diamine as a diamine component and the specific acid dianhydride as an acid dianhydride component exhibit solubility in organic solvents and tend to have high transparency and mechanical strength.

[0087] From the viewpoint of solubility and transparency in organic solvents, among specific acid dianhydrides, 4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride (BPADA), 3,4'-oxobisphthalic anhydride (a-ODPA), 4,4'-oxobisphthalic anhydride (s-ODPA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA), and 5,5'-(9H-fluorene-9-idene bis(2-methyl-4,1-phenylene)bis[1,3-dihydro]fluorene dianhydride are preferred. [1,3-dioxo-5-isobenzofuran carboxylate] (TBIS.MPN), spiro[fluorene-9,9'-xanthan]-2',3',6',7'-tetracarboxylic acid dianhydride (SFDA), p-phenylene bis(trimethoxymonoester anhydride) (TMHQ), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-diyl ester (OCBP-TME), and bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester (TAHMBP).

[0088] From the viewpoint of UV resistance of polyamide-imide, acid dianhydrides with ether bonds, fluorene structures, and xanthones are preferred among specific acid dianhydrides. From the viewpoint of solvent solubility and mechanical strength, BPADA, a-ODPA, s-ODPA, BPAF, BPF-PA, and SFDA are particularly preferred. These acid dianhydrides do not have ester bonds and do not undergo Fries rearrangement induced by UV light, thus reducing the likelihood of coloration of polyamide-imide when exposed to UV light. Furthermore, from the viewpoint of compatibility with acrylic resins described later, acid dianhydrides with ether bonds, fluorene structures, and xanthones are also preferred as specific acid dianhydrides.

[0089] From the viewpoint of making polyamide-imide soluble in organic solvents, the total amount of a specific acid dianhydride relative to the total amount of the acid dianhydride component is preferably 15 mol% or more, more preferably 20 mol% or more, and even more preferably 25 mol% or more, and can be 30 mol% or more, 35 mol% or more, 40 mol% or more, 45 mol% or more, or 50 mol% or more. The total amount of a specific acid dianhydride relative to the total amount of the acid dianhydride component can be 100 mol%, or it can be 95 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, or 70 mol% or less.

[0090] (Acid dianhydrides other than specific acid dianhydrides)

[0091] Polyamide-imides may contain dianhydrides other than specific acid dianhydrides as dianhydride components. Examples of such dianhydrides include alicyclic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. From the viewpoint of the environmental safety of polyamide-imides, it is preferable that they do not contain -C-CF3 and -C-CF2-C-, and particularly preferable that they do not contain fluorine atoms.

[0092] Alicyclic tetracarboxylic dianhydrides only require having at least one alicyclic structure, and can contain both alicyclic and aromatic rings in a single molecule. The alicyclic ring can be polycyclic or spirocyclic. Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydrides, 1,2,3,4-cyclopentanetetracarboxylic dianhydrides, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydrides, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydrides, 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydrides, and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5 '',6,6''-tetracarboxylic acid dianhydride, 2,2'-bisnorbornene-5,5',6,6'-tetracarboxylic acid dianhydride, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid-1,4:2,3-dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, cyclohexane-1,4-diylbis(methylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester), 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5,5'-[cyclohexylidene bis(4,1-phenyleneoxy)]bis-1,3-isobenzofurandione, 5-isobenzofuran carboxylic acid, 1,3-dihydro-1,3-dioxo-5,5'-[1,4-cyclohexanediylbis(methylene)] ester, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 3,5,6-tricarboxylated norbornane- 2-Acetic acid 2,3:5,6-dianhydride, decahydro-1,4,5,8-dimethylbridged naphthalene-2,3,6,7-tetracarboxylic acid dianhydride, tricyclic [6.4.0.0(2,7)]dodecane-1,8:2,7-tetracarboxylic acid dianhydride, octahydro-1H,3H,8H,10H-biphenyl[4a,4b-c:8a,8b-c']difuran-1,3,8,10-tetraone, ethylene glycol bis(hydrogenated trimellitic anhydride) ester, decahydro[2]benzopyrano[6,5,4,-def][2]benzopyran-1,3,6,8-tetraone, etc. By including alicyclic tetracarboxylic acid dianhydride as an acid dianhydride component in addition to specific acid dianhydrides, there is a tendency to improve the mechanical strength of polyamide imides. In addition, by including alicyclic tetracarboxylic dianhydride as the acid dianhydride component in polyamide-imide, there is a tendency for polyamide-imide to have higher compatibility with acrylic resins.

[0093] From the viewpoint of transparency and mechanical strength, the following alicyclic tetracarboxylic dianhydrides are preferred among polyamide-imides: 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride (TDA-100), bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BEDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride (BODA), and 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydride (H-BPDA). From the viewpoint of mechanical strength, tetracarboxylic anhydrides with two anhydride groups bonded to one alicyclic ring are preferred, and CBDA is particularly preferred.

[0094] When alicyclic tetracarboxylic dianhydride is used in addition to a specific acid dianhydride, the amount of alicyclic tetracarboxylic dianhydride can be 1 mol% or more, 3 mol% or more, 5 mol% or more, 10 mol% or more, 12 mol% or more, or 15 mol% or more relative to the total amount of acid dianhydride. There is a tendency that the higher the amount of alicyclic tetracarboxylic dianhydride, the higher the mechanical strength. From the viewpoint of ensuring the solubility of polyamide-imide in organic solvents, the amount of alicyclic tetracarboxylic dianhydride is preferably 80 mol% or less relative to the total amount of acid dianhydride, more preferably 60 mol% or less, and even more preferably 50 mol% or less, and can be 40 mol% or less, 30 mol% or less, or 20 mol% or less. Furthermore, polyamide-imides with alicyclic tetracarboxylic dianhydride as the acid dianhydride component within the above range tend to have excellent compatibility with acrylic resins.

[0095] Examples of aromatic tetracarboxylic dianhydrides other than specific acid dianhydrides include pyromellitic dianhydride (PMDA), 1,2,3,4-benzenetetracarboxylic dianhydride (MPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA). The aromatic tetracarboxylic dianhydrides include α-BPDA, s-BPDA, i-BPDA, PMDA, MPDA, and DSDA. Among these, α-BPDA, s-BPDA, i-BPDA, PMDA, MPDA, and DSDA are preferred from the perspective of improving mechanical strength.

[0096] When aromatic tetracarboxylic dianhydrides other than the specific acid dianhydride are used, the amount of aromatic tetracarboxylic dianhydrides other than the specific acid dianhydride can be 1 mol% or more, 3 mol% or more, 5 mol% or more, 10 mol% or more, 12 mol% or more, or 15 mol% or more relative to the total amount of acid dianhydride. From the viewpoint of ensuring the solubility of polyamide-imide in organic solvents, the amount of aromatic tetracarboxylic dianhydrides other than the specific acid dianhydride is preferably 80 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, and can be 40 mol% or less, 30 mol% or less, or 20 mol% or less.

[0097] Polyamide imides may contain chain aliphatic tetracarboxylic dianhydrides such as ethylene tetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, and meso-butane-1,2,3,4-tetracarboxylic dianhydride as acid dianhydride components.

[0098] The amount of fluorine-containing dianhydride relative to the total amount of dianhydride in polyamide-imide is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, and can be 5 mol% or less, 1 mol% or less, or 0.5 mol% or less. Polyamide-imide may not contain fluorine-containing dianhydride as its dianhydride component.

[0099] Among fluorine-containing dianhydrides, those with a trifluoromethyl group bonded to a carbon atom (-C-CF3) and / or with carbon atoms bonded to both ends of a difluoromethylene group (-C-CF2-C-) exhibit low decomposability, raising concerns about environmental safety. In particular, dianhydrides with a structure having CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring (e.g., 4,4'-(hexafluoroisopropylidene)phthalic anhydride, 9,9-bis(trifluoromethyl)xanthentetracarboxylic anhydride, 9-trifluoromethylxanthentetracarboxylic anhydride) exhibit low environmental decomposability. Therefore, from the viewpoint of the environmental safety of polyamide-imide, it is preferable to have dianhydrides that are substantially free of these dianhydrides. Relative to the total amount of dianhydride in polyamide-imide, the amount of dianhydride with CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring is preferably less than 0.5 mol%, and can be less than 0.3 mol%, less than 0.1 mol%, or less than 0.05 mol%, or even 0.

[0100] (polyacids)

[0101] As mentioned above, in addition to diamines and tetracarboxylic acid dianhydrides, dicarboxylic acids and / or tricarboxylic acid anhydrides are used as polyacid components, thereby obtaining polyamide imides containing structures derived from dicarboxylic acids as shown in general formula (VIa) and / or structures derived from tricarboxylic acid anhydrides as shown in general formula (VIIa).

[0102] Examples of dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, octanoic acid, azelaic acid, sebacic acid, and dodecanoic 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'-hydroxydibenzoic acid, 4,4'-biphenyl 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, 1,3-cyclopentanedicarboxylic acid, and di(cyclohexyl)-4,4'-dicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophene dicarboxylic acid and 2,5-furan dicarboxylic acid.

[0103] Examples of tricarboxylic acid anhydrides include trimellitic anhydride derivatives such as 2-fluorotriphenyltrimellitic anhydride, 5-fluorotriphenyltrimellitic anhydride, 6-fluorotriphenyltrimellitic anhydride, 2,5-difluorotriphenyltrimellitic anhydride, 2,6-difluorotriphenyltrimellitic anhydride, 5,6-difluorotriphenyltrimellitic anhydride, and 2,5,6-trifluorotriphenyltrimellitic anhydride.

[0104] From the viewpoint of the solubility of polyamide-imide, aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and trimellitic anhydride are preferred as polybasic acids, with aromatic dicarboxylic acids being particularly preferred. Among aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, 4,4'-biphenyl dicarboxylic acid, and 4,4'-hydroxybenzoic acid are preferred, with terephthalic acid and isophthalic acid being the most preferred, and terephthalic acid being particularly preferred. Among alicyclic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and di(cyclohexyl)-4,4'-dicarboxylic acid are preferred, with 1,4-cyclohexanedicarboxylic acid being particularly preferred.

[0105] In the preparation of polyamide imide and polyamic acid as its precursor, polyacid derivatives such as dicarboxylic acid diacyl chloride, dicarboxylic acid ester, dicarboxylic anhydride, and tricarboxylic anhydride acyl chloride can be used to replace polyacids.

[0106] <Ratio of amide structures in polyamide-imide>

[0107] In the polyamide-imide, the total amount of the structures derived from tetracarboxylic dianhydrides (IVa), dicarboxylic acids (VIa), and tricarboxylic anhydrides (VIIa) relative to 100 moles of the diamine-derived structure shown in general formula (Va) is preferably 90 to 110 moles. The total amount of the structures in general formula (IVa), (VIa), and (VIIa) relative to 100 moles of the structure in general formula (Va) can be 93 to 107 moles, 95 to 105 moles, 97 to 103 moles, or 99 to 101 moles.

[0108] The ratio of the total number of structures of general formula (VIa) and general formula (VIIa) to the total number of structures of general formula (IVa) and general formula (VIa) and general formula (VIIa) is 1 to 99 mol%. The ratio of the structure of general formula (IVa) to the structure of general formula (VIa) is approximately equal to the ratio of the imide structure of general formula (I) to the amide structure of general formula (II), and the ratio of the structure of general formula (IVa) to the structure of general formula (VIIa) is approximately equal to the ratio of the imide structure of general formula (I) to the amide-imide structure of general formula (III). The ratio of the total of the structures of general formula (VIa) and general formula (VIIa) to the total of the structures of general formula (IVa) and general formula (VIa) and general formula (VIIa) can be 5 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, or it can be less than 80 mol%, less than 75 mol%, less than 70 mol%, less than 65 mol%, or less than 60 mol%.

[0109] The higher the ratio of the structures of general formula (VIa) and (VIIa), that is, the higher the ratio of amide structures, the more the polyamide imide is soluble in organic solvents.

[0110] In this embodiment, the amount of polyacid relative to diamine component in the polyamide-imide, i.e., the total ratio of structural units of general formula (VI) and general formula (VII) to structural units of general formula (V), can be 5 mol% or more, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, or 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, or 60 mol% or less.

[0111] <Content of specific fluorine structures in polyamide-imide>

[0112] As described above, it includes components selected from CF3-O- and -(CF2-O). n - and -O- (CF2-CF2-O) n Polyamide-imide containing one or more diamines (specific diamines) as diamine components does not substantially contain structures such as -C-CF3, -C-CF2-C-, and exhibits solubility in organic solvents.

[0113] To reduce the environmental residue of fluorinated compounds, polyamide-imide preferably uses a small amount of monomers having a specific fluorine structure. A specific fluorine structure refers to the structure excluding those containing only the constituent elements of the following structural formula (i) from those containing trifluoromethyl (CF3-), and the structure excluding those containing only the constituent elements of the following structural formula (ii) from those containing difluoromethylene (-CF2-).

[0114] CF3-X (i)

[0115] X-CF2-X' (ii)

[0116] In equations (i) and (ii), X is either -OR or -NRR', and in equation (ii), X' is any one of -H, -CH3, aromatic, -C(O)-, -OR'', -SR'', and NR''R'''. R, R', R'', and R''' are each independently any one of -H, -CH3, -CH2-, aromatic, and -C(O)-.

[0117] From the viewpoint of improving environmental decomposability, the amount of fluorine atoms contained in a specific fluorine structure in 1 kg of polyamide-imide is preferably less than 500 mg, more preferably less than 300 mg, even more preferably less than 100 mg, and particularly preferably less than 50 mg.

[0118] <Preparation of Polyamide Imide>

[0119] There are no particular limitations on the preparation method of polyamide-imide. Generally, polyamic acid, as a precursor of polyamide-imide, is prepared by reacting a diamine with a tetracarboxylic dianhydride and a polybasic acid or its derivative. The polyamic acid is then dehydrated and cyclized (imidized) to obtain the polyamide-imide. As described above, by adjusting the composition of the monomers constituting the polyamide-imide, namely the type and ratio of the dianhydride, polybasic acid or its derivative, and diamine, polyamide-imide with solubility and transparency in organic solvents can be obtained.

[0120] There are no particular limitations on the preparation method of polyamic acid, and all known methods can be used. For example, a polyamic acid solution is obtained by dissolving the dianhydride and a polybasic acid or its derivative in an organic solvent in a molar ratio approximately equimolar to that of the diamine (90:100 to 110:100 molar ratio) and stirring. The concentration of the polyamic acid solution is typically 5 to 35% by weight, preferably 10 to 30% by weight. At concentrations within this range, the polyamic acid obtained by polymerization has a suitable molecular weight, and the polyamic acid solution has a suitable viscosity.

[0121] During the polymerization of polyamic acid, to suppress ring-opening of the dianhydride, it is preferable to add the dianhydride to the diamine. When adding multiple diamines and multiple dianhydrides, they can be added all at once or in multiple stages. By adjusting the order of monomer addition, the various properties of the polyamide-imide can also be controlled.

[0122] There are no particular limitations on the organic solvents used in the polymerization of polyamic acid, as long as they do not react with diamines and dianhydrides and can dissolve polyamic acid. Examples of organic solvents include urea solvents such as methylurea and N,N-dimethylethylurea; sulfoxide or sulfone solvents such as dimethyl sulfoxide, diphenyl sulfone, and tetramethyl sulfone; amide solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, and hexamethylphosphotriamide; haloalkyl solvents such as chloroform and dichloromethane; 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 appropriate combinations as needed. From the perspective of the solubility and polymerization reactivity of polyamic acid, DMAc, DMF, NMP, etc. are preferred.

[0123] Polyamide-imide is obtained by dehydration and cyclization of polyamic acid. Examples of methods for preparing polyamide-imide from a polyamic acid solution include adding a dehydrating agent and an imidization catalyst to the polyamic acid solution and performing imidization in solution. To promote imidization, the polyamic acid solution can be heated. By mixing the solution containing the polyamide-imide generated from the imidization of polyamic acid with a poor solvent, the polyamide-imide resin precipitates as a solid. By separating the polyamide-imide resin as a solid, impurities, residual dehydrating agents, and imidization catalysts generated during the synthesis of polyamic acid can be cleaned / removed using the poor solvent, preventing coloration and an increase in the yellow index of the polyamide-imide. Furthermore, by separating the polyamide-imide resin as a solid, solvents suitable for film formation, such as low-boiling-point solvents, can be used when preparing solutions for film fabrication.

[0124] The molecular weight of the polyamide-imide (weight-average molecular weight converted from polyethylene oxide by gel permeation chromatography (GPC)) is preferably 10,000 to 1,000,000, more preferably 20,000 to 500,000, and even more preferably 40,000 to 300,000. If the molecular weight is too small, the film strength may be insufficient. If the molecular weight is too large, the polyamide-imide resin may have poor solubility and compatibility with other resins.

[0125] Polyamide-imide is preferably soluble in organic solvents. Specifically, polyamide-imide is preferably dissolved in dimethylformamide (DMF) at a concentration of 1% by weight or more at 23°C. In addition to being soluble in amide solvents such as DMF, polyamide-imide is also preferably soluble in non-amide solvents. Examples of non-amide solvents include ketone solvents such as acetone and methyl ethyl ketone, haloalkyl solvents such as chloroform and dichloromethane, and ester solvents such as ethyl acetate and γ-butyrolactone. Compared to amide solvents, non-amide solvents have lower boiling points, making it easier to remove residual solvents during film production. Therefore, an increase in the production rate of polyamide-imide films soluble in non-amide solvents is expected. Polyamide-imide is particularly preferably soluble in dichloromethane.

[0126] [Resin Composition]

[0127] The polyamide-imide of the present invention exhibits solubility in organic solvents and compatibility with other resins. The polyamide-imide of the present invention is particularly compatible with acrylic resins and can be used in the form of resin compositions comprising polyamide-imide and acrylic resins.

[0128] <Acrylic Resins>

[0129] Examples of acrylic resins include poly(meth)acrylates such as polymethyl methacrylate, methyl methacrylate-(meth)acrylate copolymers, methyl methacrylate-(meth)acrylate copolymers, methyl methacrylate-acrylate-(meth)acrylate copolymers, and methyl methacrylate-styrene copolymers. The stereoregularity of the polymer is not particularly limited; it can be any of the isotactic, syndiotactic, or atactic configurations.

[0130] From the viewpoints of transparency, compatibility with polyamide-imide, and mechanical strength of molded products such as films, acrylic resins preferably use methyl methacrylate (MMA) as the main structural unit. The amount of MMA relative to the total monomer content in the acrylic resin is preferably 60% by weight or more, but can be 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The acrylic resin can be a homopolymer of MMA.

[0131] Acrylic resins can be resins incorporating imide or lactone ring structures. Such modified polymers are preferably acrylic polymers in which imide or lactone ring structures have been introduced into the methyl methacrylate content within the aforementioned range. That is, in acrylic resins modified by introducing imide or lactone ring structures, the total amount of methyl methacrylate and the modified methyl methacrylate structure is preferably 60% by weight or more, and can be 70% by weight or more, 80% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The modified polymer can be a homopolymer of methyl methacrylate incorporating imide or lactone ring structures.

[0132] By introducing an imide structure into acrylic polymers such as methyl methacrylate, there is a tendency to increase the glass transition temperature of acrylic resins. Furthermore, since acrylic resins contain an imide structure, their compatibility with polyamide-imides is sometimes improved. For example, certain polyamide-imide resins can exhibit compatibility with acrylic resins having a glutarimide structure even when they do not show compatibility with polymethyl methacrylate.

[0133] Acrylic resins with a glutarimide structure, such as those described in Japanese Patent Application Publication No. 2010-261025, are obtained by heating and melting polymethyl methacrylate resin and treating it with an imidizing agent. Commercially available products such as "PLEXIMID TT70" and "PLEXIMID 8805" manufactured by EVONIK can also be used as imide-modified polymethyl methacrylates.

[0134] When acrylic resins have a glutarimide structure, the glutarimide content can be 3% or more by weight, 10% or more by weight, 20% or more by weight, 30% or more by weight, or 50% or more by weight. The glutarimide content is determined by the acrylic resin... 1 The imidization rate (introduction rate) of the glutarimide structure is determined by ¹H-NMR spectroscopy and then calculated by weight conversion. For example, in methyl methacrylate with the introduced glutarimide structure, the imidization rate Im = B / (A+B) is calculated from the area A of the peak of the O-CH3 protons derived from methyl methacrylate (around 3.5~3.8 ppm) and the area B of the peak of the N-CH3 protons derived from glutarimide (around 3.0~3.3 ppm).

[0135] From the viewpoint of the heat resistance of the resin composition and the molded article, the glass transition temperature of the acrylic resin is preferably 100°C or higher, more preferably 110°C or higher, and can be 115°C or higher or 120°C or higher.

[0136] From the viewpoints of solubility in organic solvents, compatibility with the aforementioned polyamide-imide, and strength of the molded article, the weight-average molecular weight (converted to polystyrene) of the acrylic resin is preferably 5,000 to 5,000,000, more preferably 10,000 to 2,000,000, and can 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 be reduced. If the molecular weight of the acrylic resin is too high, the film-forming properties may be poor.

[0137] From the viewpoint of thermal and light stability of the resin composition and film, acrylic resins preferably have low contents of reactive functional groups such as olefinic unsaturated groups and carboxyl groups. The iodine value of the acrylic resin is preferably 10.16 g / 100g (0.4 mmol / g) or less, more preferably 7.62 g / 100g (0.3 mmol / g) or less, and even more preferably 5.08 g / 100g (0.2 mmol / g) or less. The iodine value of the acrylic resin can be 2.54 g / 100g (0.1 mmol / g) or less or 1.27 g / 100g (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 can be 0.1 mmol / g or less, 0.05 mmol / g or less, or 0.03 mmol / g or less. By lowering the acid value, there is a tendency to improve the stability of acrylic resins and their compatibility with polyamide-imide.

[0138] Preparation of resin compositions comprising polyamide-imide and acrylic resins

[0139] A resin composition is prepared by mixing the above-mentioned polyamide-imide resin with an acrylic resin. The polyamide-imide resin and acrylic resin exhibit compatibility in any ratio; therefore, the ratio of polyamide-imide resin to acrylic resin in the resin composition is not particularly limited. The mixing ratio (by weight) of polyamide-imide resin to acrylic resin can be 98:2~2:98, 95:5~10:90, or 90:10~15:85. A higher proportion of polyamide-imide resin tends to result in a higher elastic modulus and superior mechanical strength of the film. A higher proportion of acrylic resin tends to result in less coloring and higher transparency of the film.

[0140] In order to fully utilize the effect of improved transparency brought about by the mixing of polyamide-imide and acrylic resin, the ratio of acrylic resin to the total amount of polyamide-imide and acrylic resin is preferably 10% by weight or more, and can 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.

[0141] Polyamide-imide is a polymer with a special molecular structure. It usually has low solubility in organic solvents and does not show compatibility with other polymers. However, as mentioned above, polyamide-imide containing specific diamine and dianhydride components shows high solubility in organic solvents and compatibility with acrylic resins.

[0142] Resin compositions comprising polyamide-imide resins and acrylic resins preferably have a single glass transition temperature in differential scanning calorimetry (DSC) and / or dynamic viscoelasticity assays (DMA). When a resin composition has a single glass transition temperature, the polyamide-imide resin and the acrylic resin can be considered completely compatible. Films comprising polyamide-imide resins and acrylic resins also preferably have a single glass transition temperature.

[0143] The resin composition can be a simple mixture of polyamide-imide resin precipitated as a solid component and acrylic resin, or it can be a compounded mixture of polyamide-imide and acrylic resin. Alternatively, when precipitating polyamide-imide resin by mixing a polyamide-imide solution with a poor solvent, acrylic resin can be mixed in the solution, causing the resin composition containing the polyamide-imide and acrylic resin to precipitate as a solid (powder).

[0144] The resin composition can be a mixed solution comprising polyamide-imide resin and acrylic resin. The method of mixing the resins is not particularly limited; they can be mixed in a solid state or in a liquid state to form a mixed solution. A polyamide-imide resin solution and an acrylic resin solution can be prepared separately, and then mixed to prepare a mixed solution of polyamide-imide resin and acrylic resin.

[0145] As a solvent for solutions containing polyamide-imide resins and acrylic resins, there are no particular limitations as long as the solvent demonstrates solubility for both polyamide-imide resins and acrylic resins. 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; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone; and haloalkyl solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and dichloromethane.

[0146] From the viewpoint of the solubility of polyamide-imide and the compatibility of polyamide-imide in solution with acrylic resins, amide-based solvents are preferred. On the other hand, from the viewpoint of solvent removal when manufacturing films and other molded articles, low-boiling-point non-amide-based solvents are preferred. From the perspective of excellent solubility for both polyamide-imide and acrylic resins, low boiling point, and easy removal of residual solvents when manufacturing films, ketone-based solvents and haloalkyl-based solvents are preferred.

[0147] The resin composition may contain organic or inorganic low-molecular-weight compounds and high-molecular-weight compounds (such as epoxy resin). The resin composition may also contain flame retardants, ultraviolet absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, microparticles, sensitizers, etc. Microparticles may include organic microparticles such as polystyrene and polytetrafluoroethylene, and inorganic microparticles such as colloidal silica, carbon, and layered silicates; these can be porous or hollow structures. Fiber-reinforced materials may include carbon fibers, glass fibers, and aramid fibers.

[0148] Resin compositions containing polyamide-imide and acrylic resins tend to have lower melt viscosity compared to polyamide-imide alone, resulting in excellent formability in injection molding, transfer molding, compression molding, and melt extrusion. Furthermore, solutions of resin compositions containing polyamide-imide and acrylic resins tend to have lower solution viscosity compared to solutions of polyamide-imide alone with the same solids concentration. Therefore, they offer excellent processability such as solution transport and high coatability, which is advantageous in reducing film thickness unevenness.

[0149] Molded articles formed from a solution of a resin composition containing polyamide-imide and acrylic resin have a lower glass transition temperature compared to molded articles formed from a solution of the same polyamide-imide alone. Therefore, when processed under the same heating conditions, there is a tendency for lower residual solvent content in the molded article. In particular, when using amide-based high-boiling-point solvents, high-temperature heating above 250°C or 300°C is sometimes required to remove the solvent. As a result, the transparency of the obtained molded article is sometimes reduced. However, if a resin composition containing polyamide-imide and acrylic resin is used, the residual solvent content can be reduced with a shorter heating time. Therefore, coloration during heating is suppressed, and molded articles with high transparency are easily obtained.

[0150] [molded articles and films]

[0151] The aforementioned polyamide-imide, and resin compositions comprising polyamide-imide and acrylic resins, can be used to form various molded articles. Examples of molding methods include injection molding, transfer molding, compression molding, blow molding, blow forming, calendering, melt extrusion, and other melt methods.

[0152] In one embodiment, the molded body is a thin film. The film can be formed by either a melt method or a solution method, but from the viewpoint of producing a film with excellent transparency and uniformity, a solution method is preferred. In the solution method, a solution containing the aforementioned polyamide-imide is coated onto a support, and the solvent is dried to remove it, thereby obtaining the film. The aforementioned polyamide-imide and acrylic resin exhibit compatibility in solution; therefore, if polyamide-imide and acrylic resin are used together, a film with high transparency can be produced by the solution method.

[0153] As a method for coating the resin solution onto the support, known methods using rod coaters, comma coaters, etc., can be applied. As the support, glass substrates, metal substrates such as SUS, metal rollers, metal strips, plastic films, etc., can be used. From the viewpoint of improving productivity, annular supports such as metal rollers or metal strips, or long strips of plastic film, are preferred as the support, and the film is manufactured by roll-to-roll. When using plastic film as the support, a material that is insoluble in the solvent of the film-forming resin can be appropriately selected.

[0154] Heating is preferably performed during solvent drying. There are no particular limitations on the heating temperature, as long as it is sufficient to remove the solvent and suppress coloration of the resulting film; it can be appropriately set from room temperature to approximately 250°C, preferably from 50°C to 220°C. The heating temperature can be increased in stages. To improve solvent removal efficiency, the resin film can be peeled off from the support and dried after a certain degree of drying. To further promote solvent removal, heating can be performed under reduced pressure.

[0155] To improve the mechanical strength of the film, it can be stretched in one or more directions. When the film is stretched, the polymer chains align along the stretching direction, thus tending to increase the in-plane strength of the film and suppress the rupture and crack formation.

[0156] As a foldable display device (foldable display), the film used for the cover film and the substrate material is repeatedly bent along the bending axis at the same location, thus requiring high mechanical strength in the direction orthogonal to the bending axis. Therefore, by arranging the film in a manner where the stretching direction is orthogonal to the bending axis, even with repeated bending, it is not easy for the film to break or crack at the bending point, thus providing a device with high bending resistance.

[0157] There are no particular limitations on the stretching conditions of the film. For example, the stretching temperature is approximately ±40°C of the glass transition temperature of the film. The stretching temperature can be approximately 120~300°C, 150~250°C, or 180~230°C.

[0158] The stretch ratio is approximately 1-200%, specifically 5-150%, 10-120%, and 20-100%. The stretch ratio (%) is expressed as 100 × (L1-L0) / L0, where L0 is the length of the film in the stretching direction before stretching (original length), and L1 is the length of the film in the stretching direction after stretching. There is a tendency for a larger stretch ratio to result in a larger tensile modulus in the stretching direction. In particular, in compatible systems of polyamide-imide and acrylic resins, the increased tensile modulus in the stretching direction tends to lead to improved flexural strength. The higher the proportion of methyl methacrylate in the monomer component of the acrylic resin, the more significant the increase in tensile modulus in the stretching direction. Excessive stretch ratios tend to reduce mechanical strength in directions orthogonal to the stretching direction, sometimes reducing the film's workability.

[0159] From the viewpoint of improving strength in any direction within a plane, thin films can be biaxially stretched. Biaxial stretching can be simultaneous or sequential. In biaxial stretching, the stretch ratio in one direction can be the same as or different from the stretch ratio in the orthogonal direction. If the stretch ratios are set differently, there is a tendency for the mechanical strength to be relatively greater in the direction with the larger stretch ratio. When using biaxially stretched thin films with anisotropic stretch ratios for foldable devices, it is preferable to arrange them with the direction of the larger stretch ratio orthogonal to the bending axis.

[0160] The thickness of the film is not particularly limited and can be appropriately set according to the application. For example, the film thickness is 5 to 300 μm. From the viewpoint of producing a film that balances self-support, flexibility, and high transparency, the film thickness is preferably 20 μm to 200 μm, and can be 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 80 μm. For films used as cover films for displays, the thickness is preferably 10 μm or more. When the film is stretched, the thickness after stretching is preferably within the above range.

[0161] The haze of the film is not particularly limited, but is preferably 10% or less, more preferably 5% or less, and even more preferably 4% or less. It can be 3.5% or less, 3% or less, 2% or less, or 1% or less. The lower the haze of the film, the more preferred. As mentioned above, since polyamide-imide exhibits compatibility with acrylic resins, films containing both polyamide-imide and acrylic resins, like films containing polyamide-imide alone, have low haze and excellent transparency.

[0162] The total light transmittance of the film is not particularly limited, but is preferably 87% or higher, more preferably 88% or higher, and can be 89% or higher or 90% or higher. Films containing polyamide-imide and acrylic resins have higher total light transmittance than films containing polyamide-imide alone, and can exhibit a total light transmittance of 90% or higher.

[0163] The yellowness index (YI) of the film is not particularly limited, but is preferably 10 or less, more preferably 5.0 or less, and can be 4.0 or less, 3.0 or less, 2.0 or less, 1.5 or less, or 1.0 or less. Films containing polyamide-imide and acrylic resins have a lower YI than films containing polyamide-imide alone, where the YI sometimes exceeds 10. By employing a mixture system with acrylic resins, the YI can be reduced. Films containing polyamide-imide and acrylic resins can achieve a low YI of 1.0 or less.

[0164] From a strength perspective, the tensile modulus of the film is preferably 2.5 GPa or higher, more preferably 3.0 GPa or higher, even more preferably 3.5 GPa or higher, and can also be 4.0 GPa or higher. The pencil hardness of the film is preferably 6B or higher, more preferably 4B or higher, and even more preferably B or higher, and can be H or higher, 2H or higher, or 3H or higher. In the compatibility system of polyamide-imide and acrylic resin, there is a tendency that the pencil hardness does not easily decrease even when the ratio of acrylic resin is increased. Therefore, it is possible to provide a film with minimal coloring and excellent transparency without significantly reducing the excellent mechanical strength characteristic of polyamide-imide.

[0165] Films containing the polyamide-imide of this invention are suitable for use as display materials due to their low coloring content and high transparency. In particular, films with high mechanical strength can be applied to surface components such as display cover windows. Furthermore, polyamide-imide is substantially free of specific fluorine structures, resulting in high biodegradability and excellent environmental safety. In practical applications, the films of this invention can be coated with antistatic layers, easy-to-adhere layers, hard coatings, anti-reflective layers, etc.

[0166] Example

[0167] The following embodiments illustrate implementations of the present invention in more detail. It should be noted that the present invention is not limited to the following embodiments.

[0168] [Preparation of polyamide-imide resin]

[0169] N,N-dimethylacetamide (DMAc) was added to a detachable flask and stirred under a nitrogen atmosphere. Diamine, tetracarboxylic acid dianhydride, and polyacid derivatives were then added in the mixture at the ratios shown in Tables 1 and 2, and the mixture was stirred under a nitrogen atmosphere for 5–10 hours to allow the reaction to proceed, yielding a polyamic acid solution with a solid content of 10% by weight.

[0170] Add 5.5 g of pyridine as an imidization catalyst to 100 g of polyamic acid solution, and after complete dispersion, add 8 g of acetic anhydride. Stir at 90 °C for 3 hours to carry out imidization. In Comparative Examples 1-4 in Table 2, the polyamide imide had low solubility in DMAc and gelled or precipitated during imidization. Therefore, the subsequent operation was not performed.

[0171] After cooling the imidized solution to room temperature, 100g of 2-propanol (hereinafter referred to as IPA) was added at a rate of 2-3 drops / second while stirring to precipitate the polyamide-imide. Another 150g of IPA was added, and after stirring for approximately 30 minutes, the mixture was filtered using a Kiriyama funnel. The resulting solid was washed with IPA and then dried in a vacuum oven set to 120°C for 12 hours to obtain the polyamide-imide resin.

[0172] [Preparation of polyamide-imide films]

[0173] The above-mentioned polyamide-imide resin was dissolved in dimethylformamide (DMF) to prepare a polyamide-imide solution with a solid content of 10% by weight. The polyamide-imide solution was coated onto an alkali-free glass plate and dried at 60°C for 15 minutes, 90°C for 15 minutes, 120°C for 15 minutes, 150°C for 15 minutes, 180°C for 15 minutes, and 200°C for 15 minutes under atmospheric atmosphere to prepare a film with a thickness of approximately 50 μm.

[0174] [Evaluation of Thin Films]

[0175] <Haze and Total Transmittance>

[0176] The film was cut into 3cm squares, and the haze and total transmittance (TT) were measured using a haze meter "HZ-V3" manufactured by Suga Test Instruments Co., Ltd., according to JIS K7136 and JIS K7361-1.

[0177] Total transmittance

[0178] The film was cut into 3cm squares, and the total transmittance (TT) was measured using a haze meter "HZ-V3" manufactured by Suga Test Instruments Co., Ltd., according to JIS K7136 and JIS K7361-1.

[0179] Yellow Index

[0180] The film was cut into 3cm squares, and the yellow index (YI) was determined using a spectrophotometer "SC-P" manufactured by Suga Test Instruments Co., Ltd., according to JIS K7373.

[0181] Tensile modulus

[0182] The film was cut into strips 10 mm wide and allowed to stand at 23°C / 55%RH for one day to adjust the humidity. The tensile modulus was then measured using the "AUTOGRAPH AGS-X" manufactured by Shimadzu Corporation under the following conditions.

[0183] Fixture spacing: 100mm

[0184] Stretching speed: 20.0 mm / min

[0185] Measurement temperature: 23℃

[0186] [Evaluation Results]

[0187] The composition of the polyamide-imides in the examples and comparative examples, as well as the evaluation results of the polyamide-imide films in the examples, are shown in Tables 1 and 2. In Comparative Examples 1 to 4, solvent-soluble polyamide-imides were not obtained, therefore only the composition is shown in Table 2.

[0188] In Tables 1, 2 and 3 described below, the composition of polyamide-imide (diamine, tetracarboxylic dianhydride and polyacid derivatives) is expressed as a molar ratio of the total amount of tetracarboxylic dianhydride to the total amount of polyacid derivatives, which is set to 100 molar parts. The compounds are referred to by the following abbreviations.

[0189] <Diamine>

[0190] TFMOB: 2,2'-bis(trifluoromethoxy)benzidine

[0191] 2,2-Bz: 2,2'-Dimethylbenzidine

[0192] 3,3'-DDS: 3,3'-Diaminodiphenylsulfone

[0193] BAFL: 9,9-bis(4-aminophenyl)fluorene

[0194] m-Tol: 4,4'-Diamino-2,2'-Dimethylbiphenyl

[0195] <Acid dianhydride>

[0196] BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride

[0197] s-ODPA: 4,4'-O-diphthalic anhydride

[0198] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydride

[0199] BPF-PA: 9,9-Bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dihydride

[0200] TBIS.MPN: 5,5'-(9H-fluorene-9-imidene bis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate]

[0201] TBIS.RXN: 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthan]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate)

[0202] TAHMBP: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-dimethyl ester

[0203] CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

[0204] PMDA: Pyromellitic dianhydride

[0205] BPDA: 3,3',4,4'-Biphenylcarboxylic acid dianhydride

[0206] <Polybasic acid derivatives>

[0207] TPC: Terephthaloyl chloride

[0208] TMAC: Trimeric triglyceride acyl chloride

[0209] [Table 1]

[0210]

[0211] [Table 2]

[0212]

[0213] The polyamide-imides of Examples 1-22, which contain a specific diamine as a diamine component, are soluble in organic solvents and can be used to make transparent films. On the other hand, the polyamide-imides of Comparative Examples 1-4, which do not contain the specific diamine, are insoluble in organic solvents.

[0214] These results show that by using a specific diamine without a specific fluorine structure as the diamine component, polyamide-imide with high environmental safety and excellent solubility and transparency in organic solvents can be obtained.

[0215] [Preparation of resin compositions of polyamide-imide and acrylic resins]

[0216] The polyamide-imide and glutarimide-modified acrylic resin of Example 1 (prepared according to "Aryl Resin Manufacturing Example 3" in Japanese Patent Application Publication No. 2018-70710; glutarimide content 33% by weight, glass transition temperature 131°C, hereinafter referred to as "HGI") were dissolved in DMF at a weight ratio of 50:50 to prepare a solution with a solid content concentration of 10% by weight. The polyamide-imide of Examples 3, 9-14, 16, 18, 21, and 22 and commercially available polymethyl methacrylate resin ("PARAPET HM1000" manufactured by KURARAY CO.,LTD., glass transition temperature: 120°C, acid value: 0.0 mmol / g, hereinafter referred to as "HM") were dissolved in DMF at a weight ratio of 50:50 to prepare a solution with a solid content concentration of 10% by weight. In all examples, the mixed resin solution was transparent, and the polyamide-imide and acrylic resin showed compatibility.

[0217] [Thin Film Production and Evaluation]

[0218] The above mixed resin solution was coated on an alkali-free glass plate and dried at 60°C for 15 minutes, 90°C for 15 minutes, 120°C for 15 minutes, 150°C for 15 minutes, 180°C for 15 minutes, and 200°C for 15 minutes under atmospheric conditions to produce a film with a thickness of about 50 μm.

[0219] The obtained films were evaluated in the same manner as the polyamide-imide films described above. The composition of the polyamide-imide, the type of acrylic resin, and the evaluation results of the films are shown in Table 3.

[0220] [Table 3]

[0221]

[0222] The films of Examples 101, 103, 109-114, 116, 118, 121, and 122, which are mixed resin films of polyamide-imide and acrylic resins, have the same mechanical strength (tensile modulus) as the films of Examples 1, 3, 9-14, 16, 18, 21, and 22, which are polyamide-imide films alone. Compared with polyamide-imide films alone, they show a tendency to improve transparency. For example, the polyamide-imide film of Example 12 has a YI greater than 10, while the film of Example 112 has a YI reduced to 4.2, with a total transmittance exceeding 90%, showing a significant improvement in transparency. In other examples, it is known that the mixed resin films of polyamide-imide and acrylic resins also have a smaller YI and higher total transmittance compared to polyamide-imide films alone, exhibiting excellent transparency.

[0223] These results show that polyamide-imide using a specific diamine as the diamine component exhibits solubility in organic solvents and excellent compatibility with acrylic resins, resulting in highly transparent films.

Claims

1. A polyamide-imide comprising a diamine component, a tetracarboxylic dianhydride component, and a polybasic acid component, wherein, As a diamine component, it contains substances selected from CF3-O- and -(CF2-O). n - and -O- (CF2-CF2-O) n - a diamine containing fluorine atoms of one or more structures, where n is an integer from 1 to 20.

2. The polyamide-imide according to claim 1, wherein, The fluorine-containing diamine is 2,2'-bis(trifluoromethoxy)benzidine, 3,3'-bis(trifluoromethoxy)benzidine, or 2,3'-bis(trifluoromethoxy)benzidine.

3. The polyamide-imide according to claim 1, wherein, As a tetracarboxylic dianhydride component, it includes one or more tetracarboxylic dianhydrides selected from the group consisting of tetracarboxylic dianhydrides having ether bonds, tetracarboxylic dianhydrides having fluorene structures, tetracarboxylic dianhydrides having xanthine structures, and bis(triphenyl esters).

4. The polyamide-imide according to claim 3, wherein, The tetracarboxylic dianhydride selected from the group consisting of tetracarboxylic dianhydrides with ether bonds, tetracarboxylic dianhydrides with fluorene structures, tetracarboxylic dianhydrides with xanthine structures, and bis(triphenylene oxide) esters is selected from 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 3,4'-oxodiphthalic anhydride, 4,4'-oxodiphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 5,5'-(9H-fluorene-9-idene bis(2-methyl-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isophenylene] It is one or more of the group consisting of [1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylic acid ester], spiro[9H-fluorene-9,9'-[9H]xanton]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylic acid ester, p-phenylene bis(trimethicone monoester anhydride), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-diyl ester and bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester].

5. The polyamide-imide according to claim 3, further comprising one or more tetracarboxylic dianhydrides selected from the group consisting of 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 1,2,3,4-phenyltetracarboxylic dianhydride and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride as the tetracarboxylic dianhydride component.

6. The polyamide-imide according to claim 1, comprising alicyclic tetracarboxylic dianhydride as a tetracarboxylic dianhydride component, wherein the amount of alicyclic tetracarboxylic dianhydride is 1 to 80 moles relative to the total amount of tetracarboxylic dianhydride component.

7. The polyamide-imide according to claim 6, wherein, The alicyclic tetracarboxylic dianhydride is selected from one or more of the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, and 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydride.

8. The polyamide-imide according to claim 1, wherein, The amount of diamine having a structure with CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring is less than 0.5 mol% relative to the total amount of diamine. The amount of tetracarboxylic dianhydride having a structure with CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring is less than 0.5 mol% relative to the total amount of tetracarboxylic dianhydride.

9. The polyamide-imide according to claim 1, which is soluble in dimethylformamide at 23°C.

10. A molded article comprising the polyamide-imide according to any one of claims 1 to 9.

11. A film comprising the polyamide-imide according to any one of claims 1 to 9.

12. A resin composition comprising the polyamide-imide according to any one of claims 1 to 9 and an acrylic resin.

13. The resin composition according to claim 12, wherein the polyamide-imide and the acrylic resin are contained in a weight ratio ranging from 98:2 to 2:

98.

14. A molded article comprising the resin composition of claim 12.

15. A film comprising the resin composition of claim 12.

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