Resin composition, molded body, and film

Abstract

The resin composition contains a polyamide-imide and a polyester. The polyester has a weight average molecular weight of more than 10,000. The polyamide-imide contains a diamine having a fluorene structure as a diamine component, and contains one or more selected from the group consisting of a bisphenol-type tetracarboxylic dianhydride, a bis(trimellitic anhydride) ester, and a tetracarboxylic dianhydride having a fluorene structure as a tetracarboxylic dianhydride component. Since the polyamide-imide and the polyester show compatibility, a molded body such as a film formed from the resin composition has high transparency.

Description

Technical Field

[0001] This invention relates to resin compositions, molded articles, and films. Background Technology

[0002] In display devices such as liquid crystal displays (LCDs), organic EL displays (OLEDs), and electronic paper displays, as well as electronic devices such as solar cells and touch panels, there is a demand for thinner, lighter, and more flexible designs. 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 the material for the cover film of a flexible display.

[0003] Polyimide and polyamide-imide exhibit superior heat resistance compared to general-purpose transparent resins, but higher transparency is required when used in applications such as cover films for displays. As a method to improve the transparency of polyamide-imide films, a resin composition made by mixing polyamide-imide with other resins has been proposed. Patent Document 2 discloses a resin composition made by mixing polyamide-imide with an acrylic resin, and Patent Document 3 discloses a resin composition made by mixing polyamide-imide with polycarbonate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2013 / 048126

[0007] Patent Document 2: International Publication No. 2023 / 132310

[0008] Patent Document 3: Japanese Patent Application Publication No. 2023-159875 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] Patent documents 1-3 describe solvent-soluble polyamide-imides that use fluoroalkyl-substituted benzidines, such as 2,2'-bis(trifluoromethyl)benzidine (TFMB), as diamines. Polyamide-imides using fluorinated compounds as diamines and / or tetracarboxylic dianhydrides exhibit excellent transparency and solvent solubility.

[0011] On the other hand, the environmental residues of organofluorine compounds (PFAS) have become a problem in recent years. Typically, the carbon-fluorine bonds in PFAS have high bond energies, making them difficult to decompose 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 degradability and have been identified as having potential health risks.

[0012] In view of the above-mentioned problems, the object of the present invention is to provide: a molded article such as a film containing polyamide-imide with excellent environmental safety and high transparency, and a resin composition used in the manufacture thereof.

[0013] Solution for solving the problem

[0014] This invention relates to resin compositions comprising polyamide-imide and polyester, and molded articles such as films comprising the resin compositions. The polyamide-imide comprises a diamine having a fluorene structure as a diamine component, and one or more tetracarboxylic dianhydrides (specific acid dianhydrides) selected from the group consisting of bisphenol-type tetracarboxylic dianhydrides, bis(triphenylamine) esters, and tetracarboxylic dianhydrides having a fluorene structure as a tetracarboxylic dianhydride component.

[0015] The ratio of the diamine having a fluorene structure to the total amount of the structure derived from the diamine (diamine component) in the polyamide-imide is preferably 50 mol% or more. The ratio of the specific acid dianhydride of the polyamide-imide to the total amount of the structure derived from the tetracarboxylic acid dianhydride (acid dianhydride component) is preferably 50 mol% or more.

[0016] 9,9-bis(4-aminophenyl)fluorene is a preferred example of a diamine having a fluorene structure.

[0017] Preferred examples of specific acid dianhydrides include 4,4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride, 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), 2,2',3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), bisphenol Z bis(triphenylene anhydride), 5,5'-[cyclododecylidene bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate), and 5,5'-spirobis(2-methyl-4,1-phenylene)). [9H-fluorene-9,9'-[9H]xanthon]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 5,5'-[9H-fluorene-9-imide-bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride and spiro[11H-difuran[3,4-b:3',4'-i]xanthon-11,9'-fluorene]-1,3,7,9-tetraone.

[0018] In polyamide-imide, preferably, the proportion of diamines containing fluorine atoms is less than 10 mol% relative to the total amount of diamine components, the proportion of tetracarboxylic acid dianhydrides containing fluorine atoms is less than 10 mol% relative to the total amount of acid dianhydrides, and the proportion of structures derived from polybasic acids containing fluorine atoms is less than 10 mol% relative to the total amount of structures derived from polybasic acids.

[0019] The polyester has a weight-average molecular weight greater than 10,000. The polyester preferably comprises one or more diols selected from the group consisting of alkylene glycols having 3 or more carbon atoms, alkenylene glycols having 3 or more carbon atoms, polyalkylene glycols, and diols having a cyclic structure, wherein the alkylene glycols having 3 or more carbon atoms are optionally branched, and the alkenylene glycols having 3 or more carbon atoms are optionally branched.

[0020] Of the aforementioned diols, diols having a fluorene structure and diols having a bisphenol derivative structure are preferred. Examples of diols having a bisphenol derivative structure include bisphenol EO adducts, bisphenol PO adducts, and other bisphenol epoxide adducts.

[0021] The resin composition may contain polyamide-imide and polyester in a weight ratio ranging from 98:2 to 2:98.

[0022] The above composition can be used to form molded articles such as thin films. The thin film can be a stretched thin film stretched along at least one direction. The in-plane birefringence ΔN and the thickness birefringence ΔP of the thin film can be less than 0.02. The thin film can have anisotropy in its in-plane tensile modulus.

[0023] The effects of the invention

[0024] The films and other molded articles formed from the resin compositions of the present invention have high light transmittance and excellent transparency. In addition, the polyamide-imide contains specific diamines and specific tetracarboxylic acid dianhydrides, and substantially does not use monomers containing fluorine atoms. The polyamide-imide exhibits compatibility with polyesters, thus resulting in low environmental residue and excellent environmental safety. Detailed Implementation

[0025] [Resin Composition]

[0026] One embodiment of the present invention is a resin composition comprising a compatible system of polyamide-imide and polyester. Due to the compatibility of the polyamide-imide and polyester, molded articles such as films formed from the resin composition exhibit transparency.

[0027] [Polyamide imide]

[0028] 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).

[0029]

[0030] 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 anhydride groups 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 anhydride and carboxyl groups from the tricarboxylic acid anhydride shown in general formula (VII).

[0031]

[0032] 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, respectively, between the anhydride group and the carboxyl group of the structure derived from a tricarboxylic anhydride (VIIa) and the structure derived from a diamine (Va).

[0033]

[0034] 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.

[0035] As described below, polyamide-imides are typically obtained as follows: polyamic acid is synthesized using polyacid derivatives such as diamines, tetracarboxylic dianhydrides, dicarboxylic dianhydrides, and tricarboxylic anhydride acyl chlorides as monomers; the amic acid at the bonded portion of the tetracarboxylic or tricarboxylic acid to the diamine is then 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. 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 is referred to as the "tetracarboxylic dianhydride component," the structure corresponding to diamine residue Y is referred to as the "diamine component," and the structure corresponding to dicarboxylic acid residue Z and tricarboxylic anhydride residue W is referred to as the "polyacid component."

[0036] The following examples illustrate the diamine, tetracarboxylic acid dianhydride, and polybasic acid components that constitute polyamide imide.

[0037] <Diamine>

[0038] (Diamine with a fluorene structure)

[0039] The polyamide-imide in embodiments of the present invention comprises a diamine having a fluorene structure as the diamine component. A diamine having a fluorene structure is a compound having a fluorene structure between two amino groups. Specific examples of diamines having a fluorene structure include the diamines shown in group (A) below.

[0040]

[0041] R in group (A) 1a R 1b R 2a R 2b R 5a and R 5b Each of the substituents can be any number of substituents, and from the viewpoint of the solubility of polyamide-imide, alkyl, phenyl, alkoxy, or halogen groups with 1 to 10 carbon atoms are preferred. m1, m2, n1, n2, k1, and k2 are each an integer from 0 to 4.

[0042] R 3a and R 3b It is an alkylene group, R 3a and R 3b They can be the same or different. p1 and p2 are each independently 0 or 1. R 6 The carbonyl group is represented by q1 and q2, which are each independently 0 or 1.

[0043] In group (A), considering the advantages of small molecular weight, relatively high proportion of fluorene backbone, solubility and transparency of polyamide-imide, and improved compatibility with polyester, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, 9,9-bis(4-amino-3-hydroxyphenyl)fluorene, and 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene are preferred, among which 9,9-bis(4-aminophenyl)fluorene (BAFL) is particularly preferred.

[0044] The amount of diamine with a fluorene structure relative to the total amount of diamine in polyamide-imide is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, particularly preferably 70 mol% or more, and can be 80 mol% or more, 90 mol% or more, or 100 mol%. The higher the proportion of diamine with a fluorene structure, the higher the mechanical strength of polyamide-imide and its compatibility with polyester.

[0045] (Other diamines)

[0046] Polyamide-imides may also contain diamines without a fluorene structure as diamine components. From the viewpoint of the environmental safety of polyamide-imides, those without -C-CF3 and -C-CF2-C- are preferred, and those without fluorine atoms are particularly preferred. Examples of diamines that are fluorine-free and can balance excellent mechanical strength and transparency include alicyclic diamines, diamines with sulfonic acid groups, diaminodiphenyl ethers, aromatic diamines, and chain aliphatic diamines.

[0047] Examples of alicyclic diamines 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), 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.

[0048] When an alicyclic diamine is used in addition to a diamine having a fluorene structure, the amount of the alicyclic diamine relative to the total amount of diamine components 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, preferably 70 mol% or less, more preferably 50 mol% or less, and can be 30 mol% or less or 20 mol% or less.

[0049] Examples of diamines containing sulfonic acid groups 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. From the viewpoint of mechanical strength, 3,3'-diaminodiphenyl sulfone (3,3'-DDS) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS) are preferred. A combination of 3,3'-DDS and 4,4'-DDS can also be used.

[0050] When a diamine with a sulfonic acid group is used in addition to a diamine with a fluorene structure, the amount of the diamine with a sulfonic acid group relative to the total amount of diamine components 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. From the viewpoint of the solubility of polyamide imide, it is preferably 50 mol% or less, more preferably 30 mol% or less, and can be 20 mol% or less or 10 mol% or less.

[0051] Examples of diaminodiphenyl ethers include 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether. When diaminodiphenyl ether is used in addition to diamines having a fluorene structure, the amount of diaminodiphenyl ether relative to the total amount of diamine 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. From the viewpoint of the solubility of polyamide-imide, it is preferably 50 mol% or less, and can be 40 mol% or less, 30 mol% or less, 20 mol% or less, or 10 mol% or less.

[0052] The total amount of diamine components in polyamide-imide is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, and may be 95 mol% or more, 99 mol% or more, or 100 mol% or more, relative to the total amount of diamine components in polyamide-imide.

[0053] Examples of aromatic diamines other than those mentioned above include 2,2'-dimethylbenzidine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminobenzoylaniline, 3,4'-diaminobenzoylaniline, 4,4'-diaminobenzoylaniline, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'-di(3-)-diphenylbenzidine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminobenzidine, 3,4'-diaminodiphenylmethane, 3,2'-di(3-)-diphenylbenzidine, 3,4'-diaminodiphenylmethane ...phenylbenzidine, 3,4'-diaminodiphenylmethane, 3,2'-diphenylbenzidine, 3,4'-diphenylbenzidine, 3,4'-diphenylbenzidine, 3,4'-diphenylbenzidine, 3,4'-diphenylbenzidine, 1,1-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, 1,2-Di(4-aminophenyl)ethane, 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(3-aminobenzoyl)benzene Benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis(4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 2,6-bis(3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]one, bis[4-(4-aminophenoxy)phenyl]one, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]thioether [4-(3-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'-diphenoxybenzophenone, 3 3'-Diamino-4,4'-Diphenyloxybenzophenone, 3,3'-Diamino-4-phenoxybenzophenone, 3,3'-Diamino-4-Biphenyloxybenzophenone, 6,6'-Bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirodiindane, 6,6'-Bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirocyclic diindane, etc.

[0054] Examples of chain-like aliphatic 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-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, and tri... Ethylene 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, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α,ω-bis(4-aminobutyl)polydimethylsiloxane, etc.

[0055] From the viewpoint of the environmental safety of polyamide-imide, the amount of fluorine-containing diamine is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and may also be 0.5 mol% or less or 0.1 mol% or less, relative to the total amount of diamine component in polyamide-imide. Polyamide-imide may also not contain fluorine-containing diamine as a 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 degradability, raising concerns about environmental safety. From the viewpoint of improving the transparency and solubility of polyamide-imides in solvents, 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 polyamide-imide in embodiments of the present invention comprises one or more tetracarboxylic dianhydrides selected from the group consisting of bisphenol-type tetracarboxylic dianhydrides, bis(triphenylamine) esters, and tetracarboxylic dianhydrides having a fluorene structure as acid dianhydrides. Hereinafter, these tetracarboxylic dianhydrides will be referred to as "specific acid dianhydrides".

[0060] Bisphenol-type tetracarboxylic acid dianhydrides are compounds represented by the following general formula (1), which can be obtained, for example, by reacting the two hydroxyl groups of bisphenols with iodobenzofuran-1,3-dione, etc.

[0061]

[0062] In general formula (1), A is any divalent organic group, with phenyl groups bonded to the carbon atoms of A at both ends. p is 1 or 2. R 1a R 1b R 2a and R 2b Each substituent can be any number of substituents, and from the viewpoint of the solubility of polyamide-imide, alkyl, phenyl, alkoxy, or halogen groups with 1 to 10 carbon atoms are preferred. m1 and m2 are each independently integers from 0 to 3, and n1 and n2 are each independently integers from 0 to 4.

[0063] Examples of divalent organic groups A include (a), (b), and (c) below. In (a), R... 3a and R 3bEach 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.

[0064]

[0065] From the viewpoint of the solubility of polyamide imide, 4,4'-(4,4'-isopropylidene diphenoxy) phthalic anhydride (BPADA) is particularly preferred as a bisphenol type tetracarboxylic acid dianhydride.

[0066] The bis(triphenyltrihydride) ester is represented by the following general formula (2).

[0067]

[0068] In general formula (2), B is any divalent organic group, with carboxyl groups bonded to carbon atoms of B at both ends. Specific examples of divalent organic groups B can be given below (i) to (x).

[0069]

[0070] The groups represented by formulas (i) to (x) are groups obtained by removing two hydroxyl groups from diols. For example, the group represented by formula (i) is a group obtained by removing two hydroxyl groups from a hydroquinone derivative that optionally has substituents on the benzene ring.

[0071] In equations (i) and (ii), R 1 R 2a and R 2b Each is independently an alkyl, alkoxy, or halogen group having 1 to 4 carbon atoms, and m, n1, and n2 are each independently an integer from 0 to 4. In formulas (iii) to (vii), R 3a R 3b R 5a R 5b R 6a and R 6b Each substituent can be any number of substituents, preferably alkyl, phenyl, alkoxy, or halogen groups having 1 to 10 carbon atoms, from the viewpoint of the solubility of polyamide-imide. k1, k2, i1, and i2 are each independently integers from 0 to 4, and h1 and h2 are each independently integers from 0 to 4. In formula (iii), R... 4 It is an alkyl, alkoxy, or halogen, and j is an integer from 0 to 10. In formula (viii), p is an integer from 1 to 10.

[0072] The bis(triphenyltrihydride) ester is preferably an aromatic ester, as B in general formula (2), and in the above (i) to (x), (i) to (vii) are preferred, of which (i) to (vi) are preferred, and (i) and (ii) are particularly preferred.

[0073] When B is a group represented by general formula (i), from the viewpoint of the mechanical properties of the resin composition, the bis(triphenylamine) ester of general formula (2) is preferably 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester) (TMHQ) represented by the following formula (2-1).

[0074]

[0075] When B is a group represented by formula (ii), from the viewpoint of the solubility of polyamide imide, the bis(triphenylamine) ester of general formula (2) is preferably 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-dimethylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester) (TAHMBP) represented by formula (2-2).

[0076]

[0077] When B is a group as shown in formula (iii), from the viewpoint of the solubility of polyamide imide, the bis(triphenylamine) ester of general formula (2) is preferably bisphenol Z bis(triphenylamine) (BPZ-TME) as shown in formula (2-3).

[0078]

[0079] When B is a group as shown in formula (iv), from the viewpoint of the solubility of polyamide imide, the bis(triphenylamine) ester of general formula (2) is preferably 5,5'-[cyclododecylidene bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate) (TBIS-DMPN) as shown in formula (2-4).

[0080]

[0081] When B is a group represented by formula (v), from the viewpoint of the solubility of polyamide imide, the bis(triphenylamine) ester of general formula (2) is preferably 5,5'-[9H-fluorene-9-idexylbis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate) (TBIS-MPN) represented by formula (2-5).

[0082]

[0083] When B is a group represented by formula (vi), from the viewpoint of the solubility of polyamide imide, the bis(triphenyl benzoic anhydride) ester of general formula (2) is preferably 5,5'-spiro[9H-fluorene-9,9'-[9H]xanton]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate) (TBIS-RXN) represented by formula (2-6).

[0084]

[0085] A tetracarboxylic dianhydride with a fluorene structure is a compound having a fluorene structure between two anhydride groups. Specifically, when the bisphenol-type tetracarboxylic dianhydride of the above general formula (1) has a fluorene structure, the dianhydride is treated as a bisphenol-type tetracarboxylic dianhydride. Similarly, when the bis(triphenylamine) ester of the above general formula (2) has a fluorene structure, the dianhydride is treated as a bis(triphenylamine) ester.

[0086] Examples of tetracarboxylic acid dianhydrides with a fluorene structure include the acid dianhydride shown in group (B) below, N,N'-(9H-fluorene-9-idene di-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxamide].

[0087]

[0088] (B) R 1a R 1b R 2a R 2b R 3a R 3b R 4a and R 4b Each substituent can be any number of times it is alkyl, phenyl, alkoxy, or halogen with 1 to 10 carbon atoms, from the viewpoint of the solubility of polyamide-imide. m1 and m2 are each independently integers from 0 to 3. n1 and n2 are each independently integers from 0 to 4. k1 and k2 are each independently integers from 0 to 2. j1 and j2 are each independently integers from 0 to 4.

[0089] R 5a and R 5b It is an alkylene group, R 5a and R 5b They can be the same or different. p1 and p2 are each independently 0 or 1. R 6 The carbonyl group is represented by q1 and q2, which are each independently 0 or 1.

[0090] In group (B), considering factors such as small molecular weight, relatively high proportion of fluorene structure, improved solubility and transparency of polyamide imide, and improved compatibility with polyester, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, and spiro[11H-difurano[3,4-b:3',4'-i]xanthon-11,9'-fluorene]-1,3,7,9-tetraone are preferred as tetracarboxylic dianhydrides with fluorene structure.

[0091] Polyamide-imides containing a diamine with a fluorene structure as the diamine component and a specific acid dianhydride as the acid dianhydride component exhibit solubility in organic solvents and tend to have high transparency and compatibility with polyesters.

[0092] From the viewpoint of solubility in organic solvents, transparency, and compatibility with polyesters, among specific acid dianhydrides, 4,4'-(4,4'-isopropylidene diphenoxy)phthalic anhydride (BPADA), 1,4-phenylene bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TMHQ), 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (TAHMBP), bisphenol Z bis(triphenylene anhydride) (BPZ-TME), and 5,5'-[cyclododecylidene bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran-carboxylate) (TBIS- DMPN), 5,5'-[9H-fluorene-9-idexylbis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate) (TBIS-MPN), 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthone]-3',6'-diylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran) 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA), and spiro[11H-difurano[3,4-b:3',4'-i]xanthon-11,9'-fluorene]-1,3,7,9-tetraone (SFDA).

[0093] From the viewpoint of UV resistance of polyamide-imide, bisphenol-type tetracarboxylic dianhydrides and dianhydrides with fluorene structures (except for dianhydrides with ester structures) are preferred among specific acid dianhydrides. These acid dianhydrides do not have ester bonds and do not undergo Fries rearrangement induced by UV light, thus making it difficult for polyamide-imide to color when exposed to UV light. From the viewpoint of compatibility between polyamide-imide and polyester, bisphenol-type tetracarboxylic dianhydrides and bis(triphenylamine) esters are preferred. From the perspective of both excellent UV resistance and compatibility with polyester, bisphenol-type tetracarboxylic dianhydrides are preferred, among which BPADA is particularly preferred.

[0094] From the viewpoint of the solubility of polyamide-imide in organic solvents and its compatibility with polyesters, the total amount of a specific acid dianhydride relative to the total amount of the acid dianhydride component is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, particularly preferably 70 mol% or more, and can be 80 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol%. The total amount of a specific acid dianhydride relative to the total amount of the acid dianhydride component 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.

[0095] (Tetracarboxylic dianhydrides other than specific acid dianhydrides)

[0096] Polyamide-imides may contain dianhydrides other than specific acid dianhydrides as dianhydride components. From the viewpoint of the environmental safety of polyamide-imides, those that do not contain -C-CF3 and -C-CF2-C- are preferred, and those that do not contain fluorine atoms are particularly preferred. Examples of such dianhydrides include alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and chain aliphatic tetracarboxylic dianhydrides.

[0097] Alicyclic tetracarboxylic dianhydrides only require 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-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydrides, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydrides, 1,2,4,5-cyclohexanetetracarboxylic dianhydrides, and 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydrides. Norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid dianhydride, 2,2'-bisnorbornane-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 anhydride, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic anhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic anhydride, 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 dianhydride, tricyclic [6.4.0.0(2,7)]dodecane-1,8:2,7-tetracarboxylic dianhydride, octahydro-1H,3H,8H,10H-biphenylenzo[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 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 an acid dianhydride component in polyamide imides, the compatibility of polyamide imides with polyesters is sometimes improved.

[0098] From the viewpoint of transparency and mechanical strength, the following are preferred 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), and 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic-3,4:3',4'-dianhydride (H-BPDA).

[0099] 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 transparency. From the viewpoint of ensuring the solubility of polyamide-imide in organic solvents, the amount of alicyclic tetracarboxylic dianhydride is preferably 50 mol% or less relative to the total amount of acid dianhydride, more preferably 40 mol% or less, and may also be 30 mol% or less or 20 mol% or less.

[0100] Examples of aromatic tetracarboxylic dianhydrides other than specific acid dianhydrides include: pyromellitic dianhydride, benzo[a]phthalic acid dianhydride, 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, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,4'-oxophthalic anhydride (3,4'-ODPA), 4,4'-oxophthalic anhydride... 4,4'-ODPA, 3,3'-O-diphthalic anhydride (3,3'-ODPA), 5,5'-Dimethylmethylenebis(phthalic anhydride), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, terphenyltetracarboxylic dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4 4'-Tetracarboxylic acid dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane Dihydric anhydride, 1,3-bis(3,4-dicarboxybenzoyl)phenyl dianhydride, 1,4-bis(3,4-dicarboxybenzoyl)phenyl dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracitetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, etc.

[0101] Among these aromatic tetracarboxylic dianhydrides, from the viewpoint of polyamide imide solubility, 3,4'-oxobisphthalic anhydride and 4,4'-oxobisphthalic anhydride are preferred, and from the viewpoint of mechanical strength, pyromellitic dianhydride and benzoyltetracarboxylic anhydride are preferred, with pyromellitic dianhydride being particularly preferred.

[0102] 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 50 mol% or less, more preferably 40 mol% or less, and may also be 30 mol% or less or 20 mol% or less relative to the total amount of acid dianhydride.

[0103] Examples of chain-like aliphatic tetracarboxylic dianhydrides include ethylene tetracarboxylic dianhydride, 1,2,3,4-butane tetracarboxylic dianhydride, and meso-butane-1,2,3,4-tetracarboxylic dianhydride.

[0104] From the perspective of the environmental safety of polyamide-imide, the amount of fluorine-containing dianhydride is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and may also be 0.5 mol% or less or 0.1 mol% or less, relative to the total amount of dianhydride in polyamide-imide. Polyamide-imide may not contain fluorine-containing dianhydrides as its dianhydride component.

[0105] 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 degradability, 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, 2,2'-bis(trifluoromethyl)-4,4',5,5'-biphenyltetracarboxylic anhydride) exhibit low environmental degradability. 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.

[0106] <Polybasic acids>

[0107] 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).

[0108] 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'-oxobisbenzoic 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 bis(cyclohexyl)-4,4'-dicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophene dicarboxylic acid and 2,5-furan dicarboxylic acid.

[0109] Examples of tricarboxylic anhydrides include trimellitic anhydride and its derivatives.

[0110] 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'-oxobisbenzoic acid are preferred, with terephthalic acid and isophthalic 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.

[0111] The total amount of terephthalic acid, isophthalic acid, 4,4'-biphenyl dicarboxylic acid, 4,4'-oxobisbenzoic acid, 1,4-cyclohexanedicarboxylic acid, bis(cyclohexyl)-4,4'-dicarboxylic acid, and trimellitic anhydride relative to the total amount of polyamide-imide is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, and can be 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more. The total amount of terephthalic acid and isophthalic acid relative to the total amount of polyamide-imide can be 50 mol% or more, 60 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, and the amount of terephthalic acid can also be within this range.

[0112] From the viewpoint of the environmental safety of polyamide-imide, the amount of fluorine-containing polyacid as a dianhydride component is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and may also be 0.5 mol% or less or 0.1 mol% or less. Polyamide-imide may not contain fluorine-containing polyacids as its dianhydride component.

[0113] Among fluorine-containing polybasic acids, those with a structure in which CF3- or -C(CF3)2- is directly bonded to the carbon atom of the aromatic ring have low degradability, raising concerns about environmental safety. Therefore, polyamide-imide is preferably substantially free of these polybasic acids. The amount of polybasic acids with CF3- or -C(CF3)2- directly bonded to the carbon atom of the aromatic ring is preferably less than 0.5 mol% relative to the total amount of polybasic acids in the polyamide-imide; it can be less than 0.3 mol%, less than 0.1 mol%, less than 0.05 mol%, or even 0.

[0114] 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.

[0115] <Ratio of amide structures in polyamide-imide>

[0116] 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.

[0117] 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), general formula (VIa), and general formula (VIIa) is 1 to 99 mol%. The ratio of the structures of general formula (IVa) to 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 structures of general formula (IVa) to 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), 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% or less, 75 mol% or less, 65 mol% or less or 60 mol% or less.

[0118] 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.

[0119] 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.

[0120] <Content of specific fluorine structures in polyamide-imide>

[0121] As described above, polyamide-imides containing a diamine with a fluorene structure as the diamine component and a specific acid dianhydride as the acid dianhydride component substantially do not contain fluorine-containing monomers, exhibiting solubility in organic solvents and compatibility with polyesters.

[0122] To reduce the environmental residue of fluorinated compounds, polyamide-imide preferably uses monomers (diamines, dianhydrides, and polybasic acids) with specific fluorine structures in small amounts. Specific fluorine structures refer to structures excluding those containing only the constituent elements of structural formula (i) from those containing trifluoromethyl (CF3-), and structures excluding those containing only the constituent elements of structural formula (ii) from those containing difluoromethylene (-CF2-).

[0123] CF3-X (i)

[0124] X-CF2-X' (ii)

[0125] 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)-.

[0126] From the viewpoint of improving environmental degradability, the amount of fluorine atoms contained in a specific fluorine structure per 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. From the viewpoint of excellent environmental degradability, the amount of fluorine atoms in per 1 kg of polyamide-imide is preferably within the above-mentioned range.

[0127] <Preparation of Polyamide Imide>

[0128] 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. There are no particular limitations on the preparation method of polyamic acid; all known methods can be used. For example, a polyamic acid solution can be obtained by dissolving the diamine in an organic solvent at approximately an equimolar ratio (90:100 to 110:100 molar ratio) of the total amount of the dianhydride and the polybasic acid or its derivative, and stirring.

[0129] The concentration of the polyamic acid solution is typically 5–35% by weight, preferably 10–30% by weight. At concentrations within this range, the polyamic acid obtained by polymerization has an appropriate molecular weight, and the polyamic acid solution has an appropriate viscosity.

[0130] 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 or 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.

[0131] 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, dianhydrides, and polybasic acids or their derivatives 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 hexamethylphosphoric triamine; haloalkane 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.

[0132] Polyamide-imide is obtained by dehydration and cyclization of polyamic acid. One method for preparing polyamide-imide from a polyamic acid solution includes 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. The solution containing the polyamide-imide generated by imidization of polyamic acid is mixed with a poor solvent, thereby precipitating the polyamide-imide resin 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.

[0133] The molecular weight of the polyamide-imide (weight-average molecular weight converted from polystyrene 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 low, the film strength may be insufficient. If the molecular weight is too high, the solubility and compatibility of the polyamide-imide with the polyester may be inconsistent.

[0134] 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, haloalkane 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, and residual solvents are easier to remove during film production. Therefore, polyamide-imide soluble in non-amide solvents is expected to improve film production efficiency. Polyamide-imide is particularly preferably soluble in dichloromethane.

[0135] [Polyester]

[0136] Polyesters are condensates of dicarboxylic acids and diols, possessing structures derived from both dicarboxylic acids and diols. From the viewpoint of ensuring the mechanical strength of molded articles such as films formed from the resin composition, polyesters with a weight-average molecular weight (Mw, converted to polystyrene) greater than 10,000 are used as polyesters. The weight-average molecular weight of the polyester is preferably 15,000 or more, more preferably 20,000 or more, and may also be 30,000 or more. From the viewpoint of ensuring compatibility with polyamide-imide and the moldability of the resin composition when molded into films, the weight-average molecular weight of the polyester is preferably 200,000 or less, more preferably 150,000 or less, further preferably 100,000 or less, and may be 80,000 or less.

[0137] Polyethylene terephthalate (PET), a representative polyester, is a condensation product of ethylene glycol and terephthalic acid. It has high crystallinity and low solubility in organic solvents. In this embodiment, a polyester soluble in organic solvents is used. The polyester is preferably soluble in organic solvents common to polyamide-imide, and particularly preferably has solubility in highly polar solvents such as amide solvents.

[0138] Polyesters only need to have a weight-average molecular weight greater than 10,000 and be soluble in organic solvents; there are no particular limitations on the dicarboxylic acid and diol components. From the viewpoint of solubility in organic solvents, amorphous materials are preferred.

[0139] <diol>

[0140] From the viewpoint of enabling polyester to be soluble in organic solvents, the diol component of the polyester preferably includes a diol having a branched alkylene group having 3 or more carbon atoms, a diol having a branched alkenylene group having 3 or more carbon atoms, a polyalkylene diol, or a diol having a cyclic structure. Hereinafter, these diols will be referred to as "specific diols".

[0141] Examples of diols having a branched alkylene group having 3 or more carbon atoms include propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentanediol, and 1,6-hexanediol. Among these, diols having a branched alkylene group having 5 or more carbon atoms are preferred, and neopentanediol and other diols having a branched alkylene group are particularly preferred. Examples of diols having a branched alkenylene group having 3 or more carbon atoms include 2-buten-1,4-diol.

[0142] Examples of polyalkylene glycols include diethylene glycol, triethylene glycol, dipropylene glycol, and polytetramethylene ether glycol.

[0143] Examples of diols with cyclic structures include 1,4-cyclohexanediol and 1,4-cyclohexanediethanol, which have cycloalkylene-like structures; isosorbide and other diols with cyclic ether structures; diols with fluorene structures; and diols with bisphenol derivative structures.

[0144] Among these, from the viewpoint of polyester solubility and compatibility with polyamide-imide, butanediol, neopentyl glycol, polytetramethylene ether glycol, diols having a fluorene structure, and diols having a bisphenol derivative structure are preferred.

[0145] Diols with a fluorene structure are diols with a fluorene skeleton between two hydroxyl groups, represented by the following general formula (3).

[0146]

[0147] In general formula (3), Ar1 and Ar2 are aromatic hydrocarbon rings. 1a and R 1b Each is an alkyl or phenyl group having 1 to 10 carbon atoms, and n1 and n2 are each an integer greater than or equal to 0. R 2a and R 2b Each is an alkyl or phenyl group with 1 to 10 carbon atoms, and n1 and n2 are each an integer from 0 to 4. R 3a and R 3b It is an alkylene group, R 5a and R 5b They can be the same or different. p1 and p2 are each an independent integer greater than or equal to 0. q1 and q2 are both 1.

[0148] Specific examples of diols represented by general formula (3) include 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis[4-(2-hydroxypropoxy)phenyl]fluorene, 9,9-bis[4-[2-(2-hydroxyethoxy)ethoxy]phenyl]-9H-fluorene, 2,2'-[(9H-fluorene-9,9-diyl)bis(naphthalene-6,2-diyloxy)]diethanol, 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene, 9,9-bis[4-(2-hydroxypropoxy)-3-phenylphenyl]fluorene, 9,9-bis{4-[2-(2-hydroxyethoxy)ethoxy]-3-phenylphenyl}fluorene, etc. Among these, from the viewpoint of improving heat resistance, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis[4-(2-hydroxypropoxy)phenyl]fluorene and 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene are preferred.

[0149] Diols with bisphenol derivative structures are diols with epoxides added to the two phenolic hydroxyl groups of bisphenol (bisphenol epoxide adducts), preferably ethylene oxide (EO) adducts and propylene oxide (PO) adducts of bisphenol. It should be noted that the diols with fluorene structures in the above general formula (3) include diols with bisphenol derivative structures, but diols with fluorene skeletons are treated as diols with fluorene structures even if they have bisphenol derivative structures.

[0150] Examples of bisphenols that do not have a fluorene skeleton include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (bisphenol AP), 2,2-bis(4-hydroxyphenyl)butane (bisphenol B), bis(4-hydroxyphenyl)diphenylmethane (bisphenol BP), 2,2-bis(3-methyl-4-hydroxyphenyl)propane (bisphenol C), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol E), bis(4-hydroxyphenyl)methane (bisphenol F), and 2,2-bis(4-hydroxy-3-methyl-4-hydroxyphenyl)propane (bisphenol C), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol E), bis(4-hydroxyphenyl)methane (bisphenol F), and 2,2-bis(4-hydroxy-3-methyl-4-hydroxyphenyl)propane (bisphenol C). 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene (bisphenol M), bis(4-hydroxyphenyl)sulfone (bisphenol S), 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene (bisphenol P), 5,5'-(1-methylethoxy)-bis[1,1'(biphenyl)-2-ol]propane (bisphenol PH), 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC), 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), etc.

[0151] From the viewpoint of polyester solubility, ethylene oxide adducts of bisphenol A, bisphenol S, and bisphenol Z are preferred among bisphenol alkyl oxide adducts.

[0152] Polyesters may contain diols other than the specific diols mentioned above as diol components. Ethylene glycol is an example of a diol other than the specific diol. When using a specific diol and ethylene glycol in combination, from the viewpoint of compatibility between the polyester and polyamide-imide, the molar ratio of the specific diol to ethylene glycol is preferably 90:10 to 10:90, but can also be 80:20 to 20:80, or 60:40 to 40:60. In other words, the amount of the specific diol relative to the total amount of the diol component is preferably 10 mol% or more, but can also be 20 mol% or more, or 40 mol% or more.

[0153] Dicarboxylic acid

[0154] There are no particular limitations on the dicarboxylic acid composition of polyesters; various aromatic and aliphatic dicarboxylic acids can be used. Aliphatic and aromatic dicarboxylic acids can be used in combination as dicarboxylic acids.

[0155] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, and biphenyl dicarboxylic acid. Other examples of aromatic dicarboxylic acids include 9,9-bis(carboxymethyl)fluorene and 9,9-bis(2-carboxyethyl)fluorene, which have a fluorene structure.

[0156] From the viewpoint of improving the solubility and mechanical strength of polyester, terephthalic acid and isophthalic acid are preferred. Terephthalic acid and isophthalic acid can be used alone or in combination. When terephthalic acid and isophthalic acid are used in combination, from the viewpoint of polyester solubility, the molar ratio of terephthalic acid to isophthalic acid is preferably 90:10 to 10:90, and can be 25:75 to 75:25 or 60:40 to 40:60. From the viewpoint of polyester solubility and mechanical strength, relative to the total amount of dicarboxylic acid in the polyester, the total amount of terephthalic acid and isophthalic acid is preferably 30 mol% or more, more preferably 40 mol% or more, further preferably 60 mol% or more, and can also be 80 mol% or more.

[0157] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and tetrahydrophthalic acid.

[0158] By including aliphatic dicarboxylic acids as the dicarboxylic acid component in the polyester, the compatibility between the polyester and polyamide-imide is sometimes improved. From the viewpoint of improving compatibility with polyamide-imide, aliphatic dicarboxylic acids with 6 to 12 carbon atoms, particularly 6 to 10 carbon atoms, are preferred. Among these, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid are preferred from the perspective of also contributing to improved solubility of the polyester.

[0159] <Other Ingredients>

[0160] As monomer components constituting the polyester, monomers other than diols and dicarboxylic acids may be used without impairing the effects of the present invention. Examples of monomers other than diols and dicarboxylic acids include polyols having three or more hydroxyl groups (e.g., trimethylolpropane, glycerol), monohydric alcohols (e.g., octanol, decanol, lauryl alcohol, myristol, cetyl alcohol, stearyl alcohol, 2-phenoxyethanol), polycarboxylic acids having three or more carboxyl groups (e.g., 1,3,4-phenyltricarboxylic acid, 1,2,4,5-phenyltetracarboxylic acid, pyromellitic acid, trimellitic acid, tetrahydrophthalic acid), monocarboxylic acids (e.g., lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid), and hydroxycarboxylic acids (e.g., lactic acid, glycolic acid, 2-hydroxybutyric acid). Compounds having one or more hydroxyl groups and / or one or more carboxyl groups, such as 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyisobutyric acid, 2-hydroxy-2-methylbutyric acid, 2-hydroxyvalerate, 3-hydroxyvalerate, 4-hydroxyvalerate, 5-hydroxyvalerate, 6-hydroxyhexanoic acid, 10-hydroxystearic acid, 4-hydroxyphenylstearic acid, 4-(β-hydroxy)ethoxybenzoic acid), lactones (e.g., β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerate, ε-caprolactone), epoxides (e.g., ethylene oxide), etc., and compounds that generate one or more hydroxyl groups and / or one or more carboxyl groups through hydrolysis.

[0161] <Preparation of Polyester>

[0162] There are no particular limitations on the polymerization method of polyesters. Various known methods can be used, such as transesterification, direct esterification followed by melt polymerization of oligomers, or further solid-state polymerization. In polyester polymerization, dicarboxylic acid derivatives such as acid anhydrides can be used as the dicarboxylic acid component.

[0163] From the viewpoint of the heat resistance and moldability of the resin composition and the molded article, the glass transition temperature (Tg) of the polyester is preferably -25 to 200°C, more preferably 15 to 180°C, even more preferably 40 to 150°C, and can be around 60 to 130°C.

[0164] Commercially available polyester resins can also be used as polyesters. Examples of commercially available polyester resins that contain diols with fluorene structures as diol components include OKP4HT (manufactured by Osaka Gas Chemicals Co., Ltd., Mw: 38,000, Tg: 142°C) and OKP4 (manufactured by Osaka Gas Chemicals Co., Ltd., Mw: 40,000, Tg: 121°C). Examples of commercially available polyester resins containing diols with bisphenol derivative structures as diol components include Elitel UE3600 (manufactured by UNITIKA LTD., Mw: 60,000, Tg: 75°C), Elitel UE3690 (manufactured by UNITIKA LTD., Mw: 46,000, Tg: 90°C), Elitel UE9100 (manufactured by UNITIKA LTD., Mw: 77,000, Tg: 19°C), and Vylon 290 (manufactured by Toyobo, Mw: 61,000, Tg: 72°C).

[0165] Examples of commercially available polyester resins containing specific diols other than those mentioned above as diol components include: Elitel UE3200G (manufactured by UNITIKA LTD., Mw: 43,000, Tg: 65℃), Elitel UE3210 (manufactured by UNITIKA LTD., Mw: 62,000, Tg: 45℃), Elitel UE3240 (manufactured by UNITIKA LTD., Mw: 50,000, Tg: 40℃), Elitel UE3500 (manufactured by UNITIKA LTD., Mw: 83,000, Tg: 15℃), Elitel UE3510 (manufactured by UNITIKA LTD., Mw: 63,000, Tg: -25℃), Elitel UE9200 (manufactured by UNITIKA LTD., Mw: 39,000, Tg: 65℃), and Elitel UE9800 (manufactured by UNITIKA LTD.). LTD. (Mw: 40,000, Tg: 85℃), Vylon 200 (Toyobo, Mw: 42,000, Tg: 67℃), Vylon 240 (Toyobo, Mw: 35,000, Tg: 60℃), Vylon 600 (Toyobo, Mw: 38,000, Tg: 47℃).

[0166] [Preparation of Resin Composition]

[0167] The above-mentioned polyamide-imide is mixed with polyester to prepare a resin composition. Polyamide-imide generally does not show compatibility with other polymers, but as mentioned above, polyamide-imide containing a specific diamine as a diamine component shows compatibility with solvent-soluble polyesters.

[0168] Whether a specific polyamide-imide is compatible with a specific polyester is determined by fabricating a 10 μm thick film containing both polyamide-imide and polyester. If the film is transparent and has a haze of less than 10%, the polyamide-imide and polyester are considered to be compatible; if the haze of the film exceeds 10%, the polyamide-imide and polyester are considered not to be compatible.

[0169] There is no particular limitation on the ratio of polyamide-imide to polyester in the resin composition. The composition ratio (by weight) of polyamide-imide to polyester can be 2:98~98:2, 10:90~90:10, 25:75~75:25, or 40:60~60:40. A higher proportion of polyamide-imide tends to result in higher mechanical strength in molded products such as films. A higher proportion of polyester tends to result in less coloring and higher transparency in molded products such as films.

[0170] In order to fully utilize the effect of improved transparency brought about by the mixing of polyamide-imide and polyester, the ratio of polyester to the total amount of polyamide-imide and polyester 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.

[0171] The resin composition can be a simple mixture of polyamide-imide resin precipitated in solid form and polyester resin, or it can be a mixture of polyamide-imide resin and polyester resin. Alternatively, when precipitating polyamide-imide resin by mixing a polyamide-imide solution with a poor solvent, polyester resin can also be mixed in the solution, causing the resin composition containing the polyamide-imide and polyester to precipitate in solid form (powder).

[0172] The resin composition can be a mixed solution containing polyamide-imide and polyester. The method of mixing the resin is not particularly limited; it can be mixed in a solid state or in a liquid state to prepare a mixed solution. Alternatively, polyamide-imide solutions and polyester solutions can be prepared separately and then mixed to prepare a mixed solution of polyamide-imide and polyester.

[0173] As a solvent for solutions containing polyamide-imide and polyester, there are no particular limitations on any solvent that exhibits solubility for both polyamide-imide and polyester. 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 haloalkane solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and dichloromethane.

[0174] Generally, polyamide-imides have low solubility in solvents, mostly dissolving only in highly polar solvents. Therefore, from the viewpoint of the solubility of polyamide-imides and the compatibility of polyamide-imides in solution with polyesters, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred. On the other hand, from the viewpoint of solvent removal when manufacturing molded articles such as films, low-boiling-point non-amide solvents are preferred. From the perspective of excellent solubility for both polyamide-imides and polyesters, low boiling point, and easy removal of residual solvents when manufacturing films, ketone solvents and haloalkane solvents are preferred.

[0175] 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.

[0176] [Molded articles and films]

[0177] The above composition can be used to form various molded articles. Examples of molding methods include injection molding, transfer molding, compression molding, blow molding, blow forming, calendering, and melt extrusion. Resin compositions containing polyamide-imide and polyester tend to have lower melt viscosity compared to polyamide-imide alone, exhibiting excellent moldability in injection molding, transfer molding, compression molding, melt extrusion, and other similar processes.

[0178] Furthermore, solutions containing resin compositions of polyamide-imide and polyester tend to have lower viscosity compared to solutions of polyamide-imide alone with the same solids concentration. Therefore, these solutions exhibit excellent processability, such as transportability, and high coatability, which is advantageous in reducing film thickness unevenness.

[0179] 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, the solution method is preferred. In the solution method, the above-mentioned solution containing polyamide-imide and polyester is coated onto a support, and the solvent is dried and removed, thereby obtaining the film.

[0180] As a method for coating the resin solution onto the support, known methods such as rod coaters or comma coaters can be used. The support can be a glass substrate, a metal substrate such as SUS, a metal roller, a metal strip, or a plastic film. From the viewpoint of improving productivity, it is preferable to use annular supports such as metal rollers or metal strips, or long strips of plastic film, to manufacture the film by roll-to-roll. When using a plastic film as the support, it is acceptable to select a material that is insoluble in the solvent used to prepare the film adhesive.

[0181] 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.

[0182] Resin compositions containing polyamide-imide and polyester have a lower glass transition temperature compared to polyamide-imide alone, as the polyamide-imide and polyester are compatible systems. This allows for low-temperature molding and processing, and reduces the coloring of molded bodies such as films.

[0183] 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 film rupture and crack formation. In the polyamide-imide-polyester compatibility system, there is a tendency for the tensile modulus of elasticity to increase in the stretching direction, resulting in improved bending resistance.

[0184] For example, in foldable display devices (foldable displays), the film used as a cover film and 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 with its stretching direction orthogonal to the bending axis, even with repeated bending, it is less likely for the film to crack or break at the bending point, thus providing a device with high bending resistance.

[0185] There are no particular limitations on the stretching conditions of the film. As stretching methods, free-end stretching, fixed-end stretching, free-end shrinkage, fixed-end shrinkage, etc., can be applied. From the viewpoint of orienting the molecules of the film in one direction, free-end stretching, represented by the method of stretching the film in the conveying direction by utilizing the difference in circumferential speed of the clamping rollers before and after the film (so-called longitudinal stretching), is preferred; or, fixed-end stretching, represented by the method of stretching the film in the conveying direction in a direction orthogonal to the conveying direction by using a tenter frame clamping device (so-called transverse stretching), is preferred.

[0186] From the viewpoint of improving strength in any direction within a plane, 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 films with anisotropic stretch ratios in foldable devices, it is preferable to arrange them with the direction of the larger stretch ratio orthogonal to the bending axis.

[0187] The stretching temperature is approximately ±40°C of the film's glass transition temperature, and can be around 120~300°C, 150~250°C, or 180~230°C. The stretching ratio is approximately 1~200%, and can be 5~150%, 10~120%, or 20~100%. There is a tendency for a larger stretching ratio to result in a greater tensile modulus in the stretching direction. On the other hand, when the stretching ratio is too large, there is a tendency for a decrease in mechanical strength in the direction orthogonal to the stretching direction, and sometimes the film's operability is reduced.

[0188] 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 10 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, a thickness of 10 μm or more is preferred. When the film is stretched, the thickness after stretching is preferably within the above range.

[0189] The haze of the film is preferably 5% or less, more preferably 4% or less, and can be 3.5% or less, 3% or less, 2% or less, or 1% or less. As mentioned above, polyamide-imide and polyester exhibit compatibility, thus a film with low haze and high transparency can be obtained. The resin composition formed by mixing polyamide-imide and polyester preferably has a haze of 5% or less when producing a film with a thickness of 30 μm.

[0190] The total light transmittance of the film is preferably 85% or more, more preferably 86% or more, even more preferably 87% or more, particularly preferably 88% or more, and can be 89% or more or 90% or more. The resin composition formed by mixing polyamide-imide and polyester preferably has a total light transmittance of 85% or more when producing a film with a thickness of 30 μm.

[0191] The yellow index (YI) of the film is not particularly limited, but is preferably 20.0 or less, more preferably 10.0 or less, and even more preferably 5.0 or less. It can be 4.0 or less, 3.0 or less, 2.0 or less, 1.0 or less, or 0.0 or less. The resin composition formed by mixing polyamide-imide with polyester preferably has a yellow index of 20.0 or less when producing a film with a thickness of 30 μm. As described above, by mixing polyamide-imide with polyester, a film with less coloring and a lower YI can be obtained compared to using polyamide-imide alone.

[0192] The tensile modulus of elasticity of the film is not particularly limited. From the viewpoint of strength, the tensile modulus of elasticity of the film at room temperature is preferably 2.0 GPa or higher, more preferably 3.0 GPa or higher, and even more preferably 4.0 GPa or higher. The tensile modulus of elasticity can be anisotropic, and the tensile modulus of elasticity in at least one direction can be 4.0 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.

[0193] The in-plane tensile modulus of elasticity of a film can be anisotropic. As described above, by stretching the film, the tensile modulus of elasticity can be made anisotropic. The difference between the tensile modulus of elasticity in the direction with the largest in-plane tensile modulus (first direction) and the tensile modulus of elasticity in the direction orthogonal to the first direction (second direction) can be 5% or more. When the difference between the tensile modulus of elasticity in the first direction and the tensile modulus of elasticity in the second direction is large, mechanical properties such as bending resistance and pencil hardness may sometimes be improved due to the orientation of polymer chains.

[0194] The pencil hardness of the film is preferably 6B or higher, more preferably 4B or higher, and can be 2B or higher, F or higher, or 2H or higher. In the polyamide-imide-polyester compatibility system, the pencil hardness does not easily decrease even when the polyester ratio 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.

[0195] The in-plane birefringence ΔN of the thin film is preferably less than 0.020, more preferably less than 0.015, even more preferably less than 0.010, and particularly preferably less than 0.006. The thickness-direction birefringence ΔP of the thin film is preferably less than 0.020, more preferably less than 0.015, even more preferably less than 0.010, and particularly preferably less than 0.006.

[0196] In-plane birefringence ΔN is the refractive index n along the direction of maximum refractive index within the plane (slow axis direction). x The refractive index n in the direction orthogonal to the slow axis (fast axis direction) within the plane y The difference, multiplied by the film thickness, is the frontal retardation of the film, obtained by multiplying the in-plane birefringence ΔN. The birefringence ΔP in the thickness direction is the refractive index n in the slow axis direction. x Refractive index n along the fast axis y The average refractive index n in the thickness direction z The difference: (n) x +n y ) / 2-n z The thickness phase difference of the thin film is obtained by multiplying the birefringence ΔP in the thickness direction by the thickness of the thin film. There is a tendency for smaller birefringence ΔN and ΔP of the thin film to improve visibility when applied to displays.

[0197] Films formed from resin compositions comprising polyamide-imide and polyester 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. Even when stretched, films formed from the aforementioned resin compositions comprising polyamide-imide and polyester exhibit low birefringence, thus possessing high transparency and balancing high strength with low birefringence. In practical applications, the films of this invention can be coated with antistatic layers, easy-to-adhere layers, hard coatings, anti-reflective layers, etc.

[0198] Example

[0199] 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.

[0200] [Preparation of polyamide-imide resin]

[0201] <Preparation of Polyamic Acid>

[0202] Dimethylformamide (DMF) was added to a separable flask and stirred under a nitrogen atmosphere. Diamine, tetracarboxylic acid dianhydride, and polyacid derivatives were added to the mixture in the proportions (mol%) shown in Table 1, followed by acetic acid. The mixture was then 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 13% by weight.

[0203] <Imidification and Separation of Polyamide-Imide Resins>

[0204] Pyridine was added to a polyamic acid solution and allowed to disperse completely. Acetic anhydride was then added, and the mixture was stirred at 90°C for 3 hours to induce imidization. The imidized solution was cooled to room temperature, and 2-propanol (IPA) was added dropwise while stirring to precipitate the polyamide-imide resin. Further addition of IPA and stirring for approximately 30 minutes resulted in filtration 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 the polyamide-imide resin.

[0205] [Preparation of resin composition (solution) and fabrication of thin films]

[0206] <Reference Example: Fabrication of Polyamide-Imide Film>

[0207] The polyamide-imide resin obtained above was dissolved in DMF to prepare a polyamide-imide solution with a solid content concentration of 10% by weight. The polyamide-imide solution was coated onto an alkali-free glass plate and dried under atmospheric atmosphere at 60°C, 90°C, 120°C, 150°C, 180°C, and 200°C for 15 minutes at each temperature to produce the films shown in Reference Examples 1, 3, and 4 in Table 2.

[0208] <Examples and Comparative Examples: Preparation of Resin Compositions of Polyamide-Iimide (PAI) and Polyesters (PEs) and Fabrication of Films>

[0209] Dissolve the polyamide-imide resins No. 1 to 15 of Table 1 and the commercially available polyester resins described below in DMF at a weight ratio of 1:1 to prepare a resin solution with a solid content of 10% by weight.

[0210] PEs1: Elitel UE9200 (a polyester containing neopentyl glycol as a diol component; manufactured by UNITIKA LTD., weight-average molecular weight 39,000, glass transition temperature: 65°C)

[0211] PEs2: Elitel UE3600 (a polyester containing bisphenol epoxide adduct as a diol component; manufactured by UNITIKALTD., weight average molecular weight 60,000, glass transition temperature 75°C)

[0212] PEs3: OKP4HT (a polyester containing a diol with a fluorene structure as the diol component; manufactured by Osaka Gas Chemicals Co., Ltd., weight average molecular weight 38,000, glass transition temperature 142°C)

[0213] The weight-average molecular weight of the polyester resin was determined using a gel permeation chromatograph manufactured by Tosoh (corresponding to the HLC-8220GPC product) under the following conditions.

[0214] Eluent: LiBr (30mM) + H3PO4 (30mM) DMF solution

[0215] Sample concentration: 0.15% by weight

[0216] Flow rate: 0.6 mL / min

[0217] Column composition: From upstream, the columns are TSK Super AW-H, TSK gel AWM-H, and TSK gel AWM-H.

[0218] Column temperature: 40℃

[0219] Detection conditions: RI, UV

[0220] Molecular weight standard: Polystyrene (Tosoh Corporation)

[0221] The above resin solution was coated onto an alkali-free glass plate and dried under atmospheric pressure at 60°C, 90°C, 120°C, 150°C, 180°C, and 200°C for 15 minutes at each temperature to produce the films shown in Table 2. In Comparative Examples 15-1 and 15-2, the films were observed to be cloudy by visual inspection, therefore the following evaluation was not performed.

[0222] [Determination of haze, total transmittance, and yellowness index]

[0223] The films from the reference examples and embodiments were cut into 3 cm squares as test samples. 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. Yellow index (YI) was measured using a spectrophotometer “SC-P” manufactured by Suga Test Instruments Co., Ltd., according to JIS K7373.

[0224] [Evaluation Results]

[0225] The composition of polyamide-imide is shown in Table 1. The types and amounts of polyamide-imide resins and polyester resins, solvents, film thickness, haze, total transmittance, and yellowness index in the reference examples, examples, and comparative examples are shown in Table 2. In Tables 1, 2, and Table 3 (described later), the compounds are referred to by the following abbreviations.

[0226] <Diamine>

[0227] BAFL: 9,9-bis(4-aminophenyl)fluorene

[0228] 3,3'-DDS: 3,3'-Diaminodiphenylsulfone

[0229] 3,4'-ODA: 3,4'-Diaminodiphenyl ether

[0230] 4,4'-ODA: 4,4'-Diaminodiphenyl ether

[0231] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0232] Tetracarboxylic dianhydride

[0233] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydride

[0234] BPF-PA: 9,9-Bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dihydride

[0235] BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)phthalic anhydride

[0236] THAHMBP: 2,2',3,3',5,5'-Hexamethylbiphenyl-4,4'-dimethylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester)

[0237] TMHQ: 1,4-Phenylidenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid ester)

[0238] TBIS-RXN: 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthan]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate)

[0239] TBIS-MPN: 5,5'-[9H-fluorene-9-imidene bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate)

[0240] TBIS-DMPN: 5,5'-[cyclododecylidene bis(2-methyl-4,1-phenylene)]bis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate)

[0241] CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

[0242] 4,4'-ODPA: 4,4'-O-diphthalic anhydride

[0243] BT-100: 1,2,3,4-Butanetetracarboxylic acid dianhydride

[0244] PMDA: Pyromellitic dianhydride

[0245] [Table 1]

[0246]

[0247] [Table 2]

[0248]

[0249] It is known that polyamide imides No. 1 to 14, which contain BPAF (a diamine with a fluorene structure) as the diamine component and specific acid dianhydrides as the acid dianhydride component, are soluble in organic solvents and compatible with polyester resins, and can form transparent films with a haze of less than 5% and a total transmittance (TT) of more than 80%.

[0250] A comparison of Reference Example 1 and Example 1-1 shows that by mixing polyamide-imide with polyester, the transparency is improved compared to films with polyamide-imide alone, resulting in films with high total transmittance and low yellow index. The same trend was observed in comparisons of Reference Example 3 with Examples 3-1-3, and Reference Example 4 with Examples 4-1-3. These results indicate that by employing a compatible system of polyamide-imide and polyester, films with high total transmittance and excellent transparency can be obtained compared to the case of polyamide-imide alone.

[0251] [Preparation of stretched film]

[0252] Similar to the examples described above, films were prepared from a mixed solution of polyamide-imide resin and polyester resin, and fixed-end stretching was performed at the stretching temperature and stretching ratio listed in Table 3 to obtain the stretched films of Examples 51-54. Polyimide films (Reference Example 56) were prepared using a polyimide resin with TFMB as the diamine component and BPADA as the dianhydride component. Films were prepared using polyimide with the same composition as in Reference Example 56, and fixed-end stretching was performed under the conditions shown in Table 3 to obtain the stretched film of Comparative Example 55.

[0253] [evaluate]

[0254] Glass transition temperature

[0255] Strips measuring 25 mm in length and 5 mm in width were cut from the unstretched film. Using a dynamic viscoelasticity measuring apparatus (UBM Rheogel-E4000), in stretching mode, with an initial chuck spacing of 15 mm, a frequency of 10 Hz, and a heating rate of 10 °C / min, dynamic viscoelasticity was measured while simultaneously increasing the temperature from 30 °C to 300 °C. The loss tangent (tanδ) was measured. The temperature at which tanδ reached its maximum value relative to temperature was taken as the glass transition temperature (Tg).

[0256] <Tension Modulus>

[0257] The film was cut into strips 10 mm wide with the stretching direction (first direction) as the long side. After conditioning at 23°C / 55%RH for 1 day, a tensile test was conducted using Shimadzu's "AUTOGRAPH AGS-X" under the following conditions, with the stretching direction as the stretching direction, and the tensile modulus of elasticity in the first direction was measured. Using a sample cut into strips with the direction orthogonal to the stretching direction (second direction) as the long side, a tensile test was conducted with the second direction as the stretching direction, and the tensile modulus of elasticity in the second direction was also measured.

[0258] Fixture spacing: 100mm

[0259] Stretching speed: 20.0 mm / min

[0260] Measurement temperature: 23℃

[0261] Birefringence

[0262] The frontal retardation R0 and thickness retardation Rth were measured using a KOBRA phase difference measuring device manufactured by Oji Measuring Instruments. The thickness phase difference retardation was calculated using the program provided with the device, based on the retardation value measured at a tilt angle of 40°, the value of R0, the film thickness, and the average refractive index measured using prism coupling. The values ​​obtained by dividing the frontal retardation R0 and the thickness retardation Rth by the film thickness, respectively, were taken as birefringence ΔN and ΔP.

[0263] Table 3 shows the types and amounts of polyamide-imide (or polyimide) resin and polyester resin, the types of solvents, the thickness of the film, the glass transition temperature, and the evaluation results of the film.

[0264] [Table 3]

[0265]

[0266] The polyimide film of Comparative Example 55 had a frontal birefringence ΔN as small as 0.0003 before stretching (refer to Example 56), but ΔN increased significantly due to stretching. In addition, the polyimide film of Comparative Example 55 had a large birefringence ΔP in the thickness direction before stretching, and ΔP increased further due to stretching.

[0267] On the other hand, although the films of Examples 51-54, which contain polyamide-imide and polyester, were stretched such that the difference in in-plane tensile modulus was 5% or more, the in-plane birefringence ΔN and the birefringence ΔP in the thickness direction of the stretched films were both less than 0.02, indicating low birefringence. Furthermore, the films of the examples maintained high transparency (low haze and high light transmittance) after stretching.

[0268] These results show that films containing polyamide-imide and polyester can improve the tensile modulus in the stretching direction while maintaining high transparency and low birefringence, thus improving mechanical strength.

Claims

1. A resin composition comprising polyamide-imide and polyester, The polyester has a weight-average molecular weight greater than 10,000. The polyamide-imide has a structure derived from diamine, a structure derived from tetracarboxylic dianhydride, and a structure derived from polybasic acid. The diamine comprises a diamine having a fluorene structure. The tetracarboxylic dianhydride comprises one or more of the group consisting of tetracarboxylic dianhydrides of general formula (1), tetracarboxylic dianhydrides of general formula (2), and tetracarboxylic dianhydrides having a fluorene structure. In general formula (1), A is any divalent organic group, and at both ends of A, the phenyl group is bonded to the carbon atoms of A, p is 1 or 2, and R 1a R 1b R 2a and R 2b Each can be an arbitrary substituent, m1 and m2 are each an integer from 0 to 3, and n1 and n2 are each an integer from 0 to 4. In general formula (2), B is any divalent organic group, and at both ends of B, the carboxyl group is bonded to the carbon atom of B.

2. The resin composition according to claim 1, wherein, The polyamide imide has a ratio of at least 50 mol% derived from diamines having a fluorene structure relative to the total amount of diamine-derived structures.

3. The resin composition according to claim 1, wherein, In the polyamide-imide, the total number of structures derived from tetracarboxylic acid dianhydrides of general formula (1), tetracarboxylic acid dianhydrides of general formula (2), and tetracarboxylic acid dianhydrides having fluorene structures relative to the total number of structures derived from tetracarboxylic acid is 50 mol% or more relative to the total number of structures derived from tetracarboxylic acid.

4. The resin composition according to claim 1, wherein, The diamine having the fluorene structure is 9,9-bis(4-aminophenyl)fluorene.

5. The resin composition according to claim 1, wherein, The tetracarboxylic dianhydride selected from the group consisting of tetracarboxylic dianhydride of general formula (1), tetracarboxylic dianhydride of general formula (2), and tetracarboxylic dianhydride having a fluorene structure is selected from the group consisting of one or more of the following substances: 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-dimethylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), bisphenol Z bis(triphenylene anhydride), 5,5'-[cyclododecylidene bis(2-methyl-4,1-phenylene)]bis(1 3-Dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 5,5'-spiro[9H-fluorene-9,9'-[9H]xanthon]-3',6'-dimethylbis(1,3-dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 5,5'-[9H-fluorene-9-imidelbis(2-methyl-4,1-phenylene)]bis( 1,3-Dihydro-1,3-dioxo-5-isobenzofuran carboxylate), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride and spiro[11H-difuran[3,4-b:3',4'-i]xanthon-11,9'-fluorene]-1,3,7,9-tetraone.

6. The resin composition according to claim 1, wherein, In the polyamide imide The ratio of structures derived from diamines containing fluorine atoms to the total number of structures derived from diamines is less than 10 mol%. The ratio of structures derived from tetracarboxylic dianhydrides containing fluorine atoms to the total amount of structures derived from tetracarboxylic dianhydrides is less than 10 mol%. The ratio of structures derived from polybasic acids containing fluorine atoms to the total number of structures derived from polybasic acids is less than 10 moles.

7. The resin composition according to claim 1, wherein, The polyester has a structure derived from dicarboxylic acid and a structure derived from diol. The diol comprises one or more selected from the group consisting of diols having 3 or more carbon atoms in a chain-like alkylene group, diols having 3 or more carbon atoms in a chain-like alkenyl group, polyalkylene diols, and diols having a cyclic structure, wherein the chain-like alkylene group having 3 or more carbon atoms may optionally have branches, and the chain-like alkenyl group having 3 or more carbon atoms may optionally have branches.

8. The resin composition according to claim 1, wherein, The polyester has a structure derived from dicarboxylic acid and a structure derived from diol. The diol comprises one or more selected from the group consisting of diols having a fluorene structure and diols having a bisphenol derivative structure.

9. The resin composition according to claim 1, wherein, The polyester has a structure derived from dicarboxylic acid and a structure derived from diol. The diol comprises a bisphenol epoxide adduct.

10. The resin composition according to claim 1, wherein, The polyamide-imide and the polyester are contained in a weight ratio ranging from 2:98 to 98:

2.

11. A molded article comprising the resin composition according to any one of claims 1 to 10.

12. A film comprising the resin composition according to any one of claims 1 to 10.

13. The film according to claim 12, wherein it is a stretched film stretched in at least one direction.

14. The thin film according to claim 12, wherein the in-plane birefringence ΔN and the thickness birefringence ΔP are both less than 0.

02.

15. The thin film according to claim 12, wherein, The difference between the tensile modulus of elasticity in the first direction, in which the elastic modulus is greatest within the film plane, and the tensile modulus of elasticity in the second direction, in which the elastic modulus is orthogonal to the first direction, is greater than 5%.

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