Resin composition, molded article and film

Abstract

The resin composition contains a solvent-soluble polyimide and a solvent-soluble polyester resin. The polyester resin contains a dicarboxylic acid component and a diol component, and satisfies at least one of (A) and (B): (A) contains, as the diol component, a diol having 4 or more carbon atoms between two hydroxyl groups; (B) contains an aliphatic dicarboxylic acid as a dicarboxylic acid component. The polyimide satisfies at least one of (1) and (2): (1) at least one of the diamine component and the tetracarboxylic dianhydride component has a fluorene skeleton; (2) The diamine component has a fluoroalkyl group, and the tetracarboxylic dianhydride component has an ester bond.

Description

Technical Field

[0001] The present invention relates to a resin composition, a molded body and a film. Background Art

[0002] In display devices such as liquid crystal, organic EL, electronic paper, solar cells, touch panels and other electronic devices, thinning, lightness and flexibility are required. By replacing the glass material used in these devices with a film material, flexibility, thinning and lightness can be achieved. As a glass substitute material, a transparent polyimide film has been developed for display substrates, cover films, etc. (for example, Patent Document 1). In addition, it is also proposed to use a polyimide having an amide structure (i.e., "polyamide-imide") as a material for a cover film (for example, Patent Document 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-6933

[0006] Patent Document 2: International Publication No. 2013 / 048126 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] Transparent polyimide has better heat resistance than general-purpose transparent resins, but requires higher transparency when used in cover films for displays, etc. In view of this problem, an object of the present invention is to provide a film having excellent transparency and a resin composition for producing the film.

[0009] Solutions for solving problems

[0010] One embodiment of the present invention relates to a resin composition comprising a solvent-soluble polyimide and a solvent-soluble polyester resin. The resin composition may contain the polyimide and the polyester resin at a weight ratio in the range of 98:2 to 2:98.

[0011] The solvent-soluble polyester resin has a condensation structure of a dicarboxylic acid component and a diol component and satisfies at least one of the following (A) and (B).

[0012] (A) containing a diol having 4 or more carbon atoms between two hydroxyl groups as a diol component;

[0013] (B) contains an aliphatic dicarboxylic acid as a dicarboxylic acid component.

[0014] The polyimide has a diamine component and a tetracarboxylic dianhydride component. The polyimide may be a polyamideimide having a dicarboxylic acid component in addition to the diamine component and the tetracarboxylic dianhydride component.

[0015] Examples of the solvent-soluble polyimide that is compatible with the polyester resin include: (1) a polyimide in which at least one of the diamine component and the tetracarboxylic acid component has a fluorene skeleton; and (2) a polyimide in which the diamine component has a fluoroalkyl group and the tetracarboxylic dianhydride component has an ester bond.

[0016] In the polyimide of (1), the ratio of tetracarboxylic dianhydride having a fluorene skeleton to the total amount of tetracarboxylic dianhydride components may be 20 mol % or more, and the ratio of diamine having a fluorene skeleton to the total amount of diamine components may be 20 mol % or more.

[0017] The polyimide may contain a diamine having a fluoroalkyl group as a diamine component and tetracarboxylic dianhydride having a fluorene skeleton as a structure derived from tetracarboxylic dianhydride. The polyimide may contain a diamine having a fluorene skeleton as a diamine component and tetracarboxylic dianhydride having a fluoroalkyl group as a tetracarboxylic dianhydride component.

[0018] In the polyimide of (1), as the tetracarboxylic dianhydride having an ester bond, bis(trimellitic anhydride) ester is preferred, and the ratio of bis(trimellitic anhydride) ester to the total amount of the tetracarboxylic dianhydride component is preferably 10 mol% or more. As a preferred example of bis(trimellitic anhydride) ester, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester can be cited.

[0019] When the polyimide contains a diamine having a fluoroalkyl group as a diamine component, the ratio of the diamine having a fluoroalkyl group to the total diamine component is preferably 20 mol% or more. Preferred examples of the diamine having a fluoroalkyl group include fluoroalkyl-substituted benzidine such as 2,2'-bis(trifluoromethyl)benzidine.

[0020] One embodiment of the present invention is a molded article comprising the resin composition, and an example of the molded article is a film. The film according to one embodiment of the present invention has a total light transmittance of 85% or more, a haze of 10% or less, and a yellowness of 5.0 or less.

[0021] Effects of the Invention

[0022] A molded product such as a film formed from the resin composition of the present invention has high light transmittance and excellent transparency. DETAILED DESCRIPTION

[0023] [Resin composition]

[0024] One embodiment of the present invention is a compatibilized resin composition comprising a polyimide resin and a polyester resin. The polyimide resin and the polyester resin are both soluble in solvents, and by making the two compatible, a film formed from the resin composition exhibits transparency.

[0025] <Polyimide>

[0026] As a polyimide showing compatibility with the polyester resin, a polyimide soluble in an organic solvent is preferred. The organic solvent-soluble polyimide is preferably soluble in N,N-dimethylformamide (DMF) at a concentration of 1% by weight or more. In addition to amide solvents such as DMF, the polyimide is particularly preferably soluble in non-amide solvents.

[0027] Polyimide is a polymer having a structural unit shown in general formula (I), and is obtained by dehydrating and cyclizing a polyamic acid obtained by addition polymerization of tetracarboxylic dianhydride (hereinafter, sometimes described as "acid dianhydride") and diamine. That is, polyimide is a polycondensate of tetracarboxylic dianhydride and diamine, and has a structure derived from acid dianhydride (acid dianhydride component) and a structure derived from diamine (diamine component). It should be noted that polyimide can also be synthesized by condensation caused by decarboxylation of diisocyanate and acid dianhydride.

[0028]

[0029] In the general formula (I), Y is a divalent organic group, and X is a tetravalent organic group. Y is a diamine residue, which is an organic group obtained by removing two amino groups from a diamine represented by the following general formula (II). X is a tetracarboxylic dianhydride residue, which is an organic group obtained by removing two anhydride groups from a tetracarboxylic dianhydride represented by the following general formula (III).

[0030]

[0031] In other words, the polyimide includes a structural unit represented by the following general formula (IIa) and a structural unit represented by the following general formula (IIIa), and has a structural unit represented by the general formula (I) by forming an imide bond between the structure (IIa) derived from a diamine and the structure (IIIa) derived from a tetracarboxylic dianhydride.

[0032]

[0033] The polyimide may contain a structural unit (amide structural unit) represented by the following general formula (IV) in addition to the imide structural unit represented by the general formula (I). A polyimide containing an amide structural unit in addition to the imide structural unit is also called a polyamideimide.

[0034]

[0035] In the general formula (IV), Y and Z are divalent organic groups. Y is a diamine residue as in the general formula (I). Z is a dicarboxylic acid residue, which is an organic group obtained by removing two carboxyl groups from a dicarboxylic acid represented by the following general formula (V). It should be noted that in the synthesis of polyamide-imide, it is preferred to use a diacyl chloride represented by the general formula (V') instead of a dicarboxylic acid. A dicarboxylic anhydride may also be used instead of a dicarboxylic acid.

[0036]

[0037] The amide structural unit represented by the general formula (V) is formed by forming an amide bond between the diamine-derived structure represented by the general formula (IIa) and the dicarboxylic acid-derived structure represented by the following general formula (Va). That is, the polyamide-imide includes the diamine-derived structure (IIa), the tetracarboxylic dianhydride-derived structure (IIIa), and the dicarboxylic acid-derived structure (Va).

[0038]

[0039] In addition, polyamideimide has the structure of the following general formula (VI) in which the structure (IIa) derived from a diamine is bonded to both ends of the structure (Va) derived from a dicarboxylic acid.

[0040]

[0041] In the general formula (VI), Y1 and Y2 are diamine residues, and Z1 is a dicarboxylic acid residue. When the part [-Y1-NH-CO-Z1-CO-NH-Y2-] in the general formula (VI) is regarded as a divalent organic group, the divalent organic group can be a diamine residue Y containing two amide bonds. That is, in the general formula (I), the diamine residue Y is a polyimide containing an amide bond, which is a polyamideimide, and the polyamideimide can be said to be a type of polyimide. Hereinafter, unless otherwise specified, the description of "polyimide" includes "polyamideimide".

[0042] As mentioned above, polyimide can be synthesized by condensation caused by decarboxylation of tetracarboxylic dianhydride and diamine, except for the method of synthesizing by tetracarboxylic dianhydride and diamine through polyamic acid, and in any synthesis method, the obtained polyimide has: the structure (tetracarboxylic dianhydride residue) X derived from acid dianhydride removing 4 carboxyl groups from tetracarboxylic dianhydride and the structure (diamine residue) Y derived from diamine removing 2 amino groups from diamine. Therefore, even if the starting raw material used in the synthesis of polyimide is not tetracarboxylic dianhydride or diamine, the structure equivalent to tetracarboxylic dianhydride residue contained in polyimide is expressed as "acid dianhydride component", and the structure equivalent to diamine residue is expressed as "diamine component". In addition, in the synthesis of polyamide-imide, dicarboxylic acid derivatives such as diacyl chlorides and dicarboxylic anhydride are used, and the obtained polyamide-imide has the structure Z (dicarboxylic acid residue) of removing 2 carboxyl groups from dicarboxylic acid. Therefore, even if the starting raw material used in the synthesis of polyimide is a dicarboxylic acid derivative, the structure equivalent to dicarboxylic acid residue is expressed as "dicarboxylic acid component".

[0043] The polyimide may contain a plurality of diamine residues Y, a plurality of tetracarboxylic dianhydride residues X, and a plurality of dicarboxylic acid residues Z.

[0044] Examples of polyimides that are compatible with polyester resins include: (1) polyimides in which at least one of the diamine component and the acid dianhydride component has a fluorene skeleton; and (2) polyimides in which the diamine component has a fluoroalkyl group and the acid dianhydride component has an ester structure. The following describes examples of diamine components and tetracarboxylic dianhydride components as monomer units constituting polyimide, and dicarboxylic acid components when the polyimide is polyamideimide.

[0045] <Diamine>

[0046] (Diamine having a fluorene skeleton)

[0047] The diamine having a fluorene skeleton is a compound in which two amino groups are bonded to a diamine residue Y having one or more fluorene skeletons. When the diamine component of the polyimide contains a fluorene skeleton, there is a tendency that the transparency and solubility of the polyimide in an organic solvent are improved, and the compatibility with the polyester resin is improved. Specific examples of the diamine having a fluorene skeleton include the diamines shown in the following (A) group.

[0048]

[0049] In each general formula of the above group (A), R is an alkyl group having 1 to 5 carbon atoms, a perfluoroalkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen group, and n is an integer of 0 to 4. In the group (A), since the smaller the molecular weight, the larger the proportion of the fluorene skeleton, the preferred diamine having a fluorene skeleton is 9,9-bis(4-aminophenyl)fluorene.

[0050] (Diamine having a fluoroalkyl group)

[0051] Examples of the diamine having a fluoroalkyl group include fluoroalkyl-substituted benzidine. Specific examples of the fluoroalkyl-substituted benzidine include 2-(trifluoromethyl)benzidine, 3-(trifluoromethyl)benzidine, 2,3-bis(trifluoromethyl)benzidine, 2,5-bis(trifluoromethyl)benzidine, 2,6-bis(trifluoromethyl)benzidine, 2,3,5-tris(trifluoromethyl)benzidine, 2,3,6-tris(trifluoromethyl)benzidine, 2,3,5,6-tetrakis(trifluoromethyl)benzidine, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2 ... 2,2',3-bis(trifluoromethyl)benzidine, 2,3,3'-tris(trifluoromethyl)benzidine, 2,2',5-tris(trifluoromethyl)benzidine, 2,2',6-tris(trifluoromethyl)benzidine, 2,3',5-tris(trifluoromethyl)benzidine, 2,3',6,-tris(trifluoromethyl)benzidine, 2,2',3,3'-tetrakis(trifluoromethyl)benzidine, 2,2',5,5'-tetrakis(trifluoromethyl)benzidine, 2,2',6,6'-tetrakis(trifluoromethyl)benzidine, and the like.

[0052] Among them, fluoroalkyl-substituted benzidine having a fluoroalkyl group at the 2-position of biphenyl is preferred, and 2,2'-bis(trifluoromethyl)benzidine (hereinafter referred to as "TFMB") is particularly preferred. By having a fluoroalkyl group at the 2-position and the 2'-position of biphenyl, the electron-withdrawing property of the fluoroalkyl group leads to a decrease in the π electron density, and the steric hindrance of the fluoroalkyl group leads to a distortion of the bond between the two benzene rings of the biphenyl, thereby reducing the planarity of the π conjugation. Therefore, the absorption end wavelength shifts to a shorter wavelength, and there is a tendency that the coloring of the polyimide is reduced and the solubility in an organic solvent is improved.

[0053] Examples of diamines having a fluoroalkyl group other than fluoroalkyl-substituted benzidine include diamines having an aromatic ring to which a fluoroalkyl group is bonded, such as 2-(trifluoromethyl)-1,4-phenylenediamine, 2,3-bis(trifluoromethyl)-1,4-phenylenediamine, 2,5-bis(trifluoromethyl)-1,4-phenylenediamine, 2,6-bis(trifluoromethyl)-1,4-phenylenediamine, 2,3,5-tris(trifluoromethyl)-1,4-phenylenediamine, and 2,3,5,6-tetrakis(trifluoromethyl)-1,4-phenylenediamine; and diamines having a fluoroalkyl group not directly bonded to an aromatic ring, such as 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane.

[0054] (Other diamines)

[0055] The polyimide may contain diamines other than those mentioned above as diamine components. From the viewpoint of obtaining a polyimide having high solubility in an organic solvent and high compatibility with a polyester resin, preferred examples of diamines other than those mentioned above (i.e., diamines not having either a fluorene skeleton or a fluoroalkyl group) include: diamines having an alicyclic structure, diamines having a sulfonic group, and diamines having a fluorine-containing group other than a fluoroalkyl group.

[0056] Examples of the diamine having an alicyclic structure include isophoronediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornene, 4,4′-methylenebis(cyclohexylamine), bis(4-aminocyclohexyl)methane, 4,4′-methylenebis(2-methylcyclohexylamine), 1,3-adamantanediamine, 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.

[0057] Examples of diamines having a sulfonic group include 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenyl sulfone, and 4,4'-bis[4-(4-aminophenoxy)phenoxy]diphenyl sulfone. By using a diamine having a sulfonic group, the solubility and transparency of the polyimide in an organic solvent may be improved, or mechanical properties such as elastic modulus and toughness may be improved. Among diaminodiphenyl sulfones, 3,3'-diaminodiphenyl sulfone (3,3'-DDS) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS) are preferred. 3,3'-DDS and 4,4'-DDS may be used in combination.

[0058] Examples of the fluorine-containing diamines include 2-fluorobenzidine, 3-fluorobenzidine, 2,3-difluorobenzidine, 2,5-difluorobenzidine, 2,6-difluorobenzidine, 2,3,5-trifluorobenzidine, 2,3,6-trifluorobenzidine, 2,3,5,6-tetrafluorobenzidine, 2,2'-difluorobenzidine, 3,3'-difluorobenzidine, 2,3'-difluorobenzidine, 2,2',3-trifluorobenzidine, 2,3,3'-trifluorobenzidine, 2,2',5-trifluorobenzidine, 2,2',6-trifluorobenzidine, 2,3',5-trifluorobenzidine, and 2,3',6-trifluorobiphenyl. Amine, 2,2',3,3'-tetrafluorobenzidine, 2,2',5,5'-tetrafluorobenzidine, 2,2',6,6'-tetrafluorobenzidine, 2,2',3,3',6,6'-hexafluorobenzidine, 2,2',3,3',5,5',6,6'-octafluorobenzidine, 2-fluoro-1,4-phenylenediamine, 2,3-difluoro-1,4-phenylenediamine, 2,5-difluoro-1,4-phenylenediamine, 2,6-difluoro-1,4-phenylenediamine, 2,3,5-trifluoro-1,4-phenylenediamine, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, 2,2'-dimethylbenzidine, etc.

[0059] Examples of diamines other than the above include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2-(3-aminophenyl)propane, and 2-(4-aminophenyl)propane. 1,1-bis(3-aminophenyl)-1-phenylethane, 1,1-bis(4-aminophenyl)-1-phenylethane, 1-(3-aminophenyl)-1-(4-aminophenyl)-1-phenylethane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminobenzoyl)benzene, 1,3-bis(4-aminobenzoyl)benzene, 1,4-bis(3-aminobenzoyl)benzene, 1,4-bis(4-aminobenzoyl)benzene, 1,3-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,3-bis( 4-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(3-amino-α,α-dimethylbenzyl)benzene, 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene, 2,6-bis(3-aminophenoxy)benzonitrile, 2,6-bis(3-aminophenoxy)pyridine, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]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-phenyloxybenzophenone, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane and other aromatic diamines.

[0060] As diamines, 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 di(3-aminopropyl)ether, diethylene glycol di(3-aminopropyl)ether, ether, triethylene glycol di(3-aminopropyl) ether, ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 1,3-bis(4-aminobutyl)tetramethyldisiloxane, α,ω-bis(3-aminopropyl)polydimethylsiloxane, α,ω-bis(3-aminobutyl)polydimethylsiloxane and other chain diamines.

[0061] (Diamine having an amide bond)

[0062] As the diamine component of the polyimide, a diamine having an amide bond can be used. For example, an amide formed by bonding a diamine to the carboxyl groups at both ends of a dicarboxylic acid is represented by the general formula (VII).

[0063]

[0064] In general formula (VII), Y is a diamine residue, and Z is a dicarboxylic acid residue. General formula (VII) shows a structure in which one dicarboxylic acid is condensed with two diamines, but two dicarboxylic acids may be condensed with three diamines, or three or more dicarboxylic acids may be condensed with four or more diamines.

[0065] As a diamine component, a polyimide containing a diamine having an amide structure represented by general formula (VII) further contains an amide bond in addition to an imide bond, and is therefore equivalent to a polyamideimide. In the synthesis of polyamideimide, a polyimide containing a structure represented by general formula (IV) (i.e., polyamideimide) can also be synthesized by using an amine-terminated amide oligomer instead of a dicarboxylic acid derivative as a monomer. A dicarboxylic acid derivative and an amine-terminated amide oligomer can be used in combination.

[0066] The dicarboxylic acid in the diamine having an amide structure represented by the general formula (VII) is not particularly limited, and various aliphatic dicarboxylic acids, aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and heterocyclic dicarboxylic acids used in the synthesis of polyamide-imide can be applied. The details of the dicarboxylic acid component will be described later. In the preparation of a compound having a condensation structure of a diamine and a dicarboxylic acid, a dicarboxylic acid derivative such as a diacyl chloride or a dicarboxylic anhydride can be used instead of a dicarboxylic acid.

[0067] As an example of a diamine having a structure represented by general formula (VII), a condensate of TFMB and a dicarboxylic acid can be cited. As the dicarboxylic acid, terephthalic acid and / or isophthalic acid are particularly preferred. For example, a diamine in which TFMB is condensed at both ends of terephthalic acid has a structure represented by the following formula (4).

[0068]

[0069] <Tetracarboxylic dianhydride>

[0070] (Acid dianhydride having a fluorene skeleton)

[0071] The acid dianhydride having a fluorene skeleton is a compound having two acid anhydride groups bonded to a tetracarboxylic dianhydride residue X having one or more fluorene skeletons. When the acid dianhydride component of the polyimide contains a fluorene skeleton, there is a tendency that the transparency and solubility of the polyimide in an organic solvent are improved, and the compatibility with the polyester resin is improved. As specific examples of the acid dianhydride having a fluorene skeleton, tetracarboxylic dianhydride shown in the following (B) group, N,N'-(9H-fluorene-9-ylidene-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide] can be cited.

[0072]

[0073] In each general formula of the above group (B), R is an alkyl group having 1 to 5 carbon atoms, a perfluoroalkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen group, and n is an integer of 0 to 4. In the group (B), the smaller the molecular weight, the larger the proportion of the fluorene skeleton is. Therefore, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride and Spiro-[11H-Difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]-fluorene]1,3,7,9-tetrone are preferred.

[0074] (Acid dianhydride having ester bond)

[0075] As the tetracarboxylic dianhydride having an ester bond, bis(trimellitic anhydride) esters represented by the following general formula (1) are mentioned.

[0076]

[0077] Q in the general formula (1) is an arbitrary divalent organic group, and carboxyl groups are bonded to carbon atoms of Q at both ends of Q. The carbon atom bonded to the carboxyl group may form a ring structure. Specific examples of the divalent organic group Q include the following (A) to (K).

[0078]

[0079] R in formula (A) 1 is a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and m is an integer of 1 to 4. The group represented by formula (A) is a group obtained by removing two hydroxyl groups from a hydroquinone derivative having a substituent on the benzene ring. Examples of hydroquinone having a substituent on the benzene ring include tert-butyl hydroquinone, 2,5-di-tert-butyl hydroquinone, and 2,5-di-tert-amyl hydroquinone. It should be noted that R 1 When the bis(trimellitic anhydride) ester is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester is equivalent to a tetracarboxylic dianhydride having a fluoroalkyl group. In the general formula (1), when Q is (A) and m=0 (i.e., there is no substituent on the benzene ring), the bis(trimellitic anhydride) ester is p-phenylene bis(trimellitic acid ester) dianhydride (abbreviation: TAHQ).

[0080] R in formula (B) 2is a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and n is an integer of 0 to 4. The group represented by formula (B) is a substituent obtained by removing two hydroxyl groups from a biphenol optionally having a substituent on a benzene ring. Examples of biphenol derivatives having a substituent on a benzene ring include 2,2'-dimethyl-4,4'-biphenol, 3,3'-dimethyl-4,4'-biphenol, 3,3',5,5'-tetramethyl-4,4'-biphenol, and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol. It should be noted that R 2 When it is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester corresponds to a tetracarboxylic dianhydride having a fluoroalkyl group.

[0081] The group represented by formula (C) is a group obtained by removing two hydroxyl groups from 4,4'-isopropylidene bisphenol (bisphenol A). The group represented by formula (D) is a group obtained by removing two hydroxyl groups from resorcinol.

[0082] p in formula (E) is an integer of 1 to 10. The group represented by formula (E) is a group obtained by removing two hydroxyl groups from a linear diol having 1 to 10 carbon atoms. Examples of the linear diol having 1 to 10 carbon atoms include ethylene glycol and 1,4-butanediol.

[0083] The group represented by the formula (F) is a group obtained by removing two hydroxyl groups from 1,4-cyclohexanedimethanol.

[0084] R in formula (G) 3 is a hydrogen atom, a fluorine atom, an alkyl group having 1 to 20 carbon atoms, or a fluoroalkyl group having 1 to 20 carbon atoms, and q is an integer of 0 to 4. The group represented by formula (G) is a group obtained by removing two hydroxyl groups from bisphenol fluorene optionally having a substituent on a benzene ring having a phenolic hydroxyl group. Examples of bisphenol fluorene derivatives having a substituent on a benzene ring having a phenolic hydroxyl group include methyl bisphenol fluorene. It should be noted that R 3 When it is a fluoroalkyl group having 1 to 20 carbon atoms, the bis(trimellitic anhydride) ester corresponds to a tetracarboxylic dianhydride having a fluoroalkyl group.

[0085] The bis(trimellitic anhydride) ester is preferably an aromatic ester, and as Q, among the above (A) to (K), preferably (A)(B)(C)(D)(G)(H)(I). Among them, (A) to (D) are preferred, and (B) and (C) are particularly preferred. When Q is a group represented by the general formula (B), from the viewpoint of the solubility of the polyimide, Q is preferably 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl represented by the following formula (B1).

[0086]

[0087] In the general formula (1), the acid dianhydride wherein Q is a group represented by the formula (B1) is bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester (abbreviation: TahmbP) represented by the following formula (3).

[0088]

[0089] Examples of tetracarboxylic dianhydrides having an ester bond other than bis(trimellitic anhydride) esters include 1,3-dihydro-1,3-dioxo-5,5′-[1,4-cyclohexanediylbis(methylene)] ester and ethylene glycol bis(hydrogenated trimellitic anhydride) ester.

[0090] (Other acid dianhydrides)

[0091] The polyimide may contain an acid dianhydride other than the above as an acid dianhydride component. From the viewpoint of obtaining a polyimide having high solubility in an organic solvent and high compatibility with a polyester resin, preferred examples of acid dianhydrides other than the above (i.e., an acid dianhydride not having any one of a fluorene skeleton and an ester bond) include: an acid dianhydride having a fluoroalkyl group, an alicyclic tetracarboxylic dianhydride, an acid dianhydride having an ether bond, and an aromatic acid dianhydride.

[0092] Examples of the tetracarboxylic dianhydride having a fluoroalkyl group include 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}-1,1,1,3,3,3-hexafluoropropane dianhydride, 1,4-bis(trifluoromethyl)pyromellitic acid dianhydride, 4-trifluoromethylpyromellitic acid dianhydride, Anhydride, 3,6-bis[3',5'-bis(trifluoromethyl)phenyl]pyromellitic dianhydride, 1-[3',5'-bis(trifluoromethyl)phenyl]pyromellitic dianhydride, N,N'-[[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis(6-hydroxy-3,1-phenylene)]bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxamide], etc. Among them, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (hereinafter referred to as "6FDA") is particularly preferred.

[0093] The alicyclic tetracarboxylic dianhydride may have at least one alicyclic structure, and may have both an alicyclic ring and an aromatic ring in one molecule. The alicyclic ring may be polycyclic or may have a spirocyclic structure.

[0094] Specific examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, meso-butane-1,2,3,4-tetracarboxylic dianhydride, 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic Acid-3,4:3',4'-dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride, 2,2'-bi-norbornane-5,5',6,6'tetracarboxylic 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 dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride , cyclohexane-1,4-diylbis(methylene)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5,5'-[cyclohexylidenebis(4,1-phenyleneoxy)]bis-1,3-isobenzofurandione, 5-isobenzofurancarboxylic acid, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, 3,5, 6-tricarboxynorbornane-2-acetic acid 2,3:5,6-dianhydride, decahydro-1,4,5,8-dimethylnaphthalene-2,3,6,7-tetracarboxylic dianhydride, tricyclo[6.4.0.0(2,7)]dodecane-1,8:2,7-tetracarboxylic dianhydride, octahydro-1H,3H,8H,10H-biphenylene[4a,4b-c:8a,8b-c']difuran-1,3,8,10-tetraone, decahydro[2]benzopyranyl[6,5,4,-def][2]benzopyran-1,3,6,8-tetraone, etc.

[0095] Among alicyclic tetracarboxylic dianhydrides, from the viewpoint of transparency and mechanical strength of the polyimide, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA) or 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic acid-3,4:3',4'-dianhydride (H-BPDA) is preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is particularly preferred.

[0096] Examples of the acid dianhydride having an ether bond include 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride, etc. Among the acid dianhydrides having an ether bond, 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride is preferred from the viewpoint of compatibility with the polyester resin.

[0097] From the viewpoint of obtaining a polyimide having high solubility in an organic solvent and high compatibility with a polyester resin, useful aromatic acid anhydrides include pyromellitic dianhydride, 1,2,3,4-pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 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 dianhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3,3',4,4'-tetracarboxylic dianhydride, 11,11-dimethyl-1H-difluoro[3,4-b:3',4'-i]xanthene-1,3,7,9(11H)-tetraone, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic dianhydride, etc. Among these, pyromellitic dianhydride and 1,2,3,4-pyromellitic dianhydride are particularly preferred as aromatic acid dianhydrides from the viewpoint of compatibility between polyimide and polyester resin.

[0098] Examples of aromatic acid dianhydrides other than the above include 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,3-bis(2,3-dicarboxyphenyl)ethane dianhydride, [(3,4-dicarboxy)benzoyl]phthalic anhydride, 1,4-bis[(3,4-dicarboxy)benzoyl]phthalic anhydride, 2,2-bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride, 2,2-bis{4-[4-(3,4-dicarboxy)phenoxy]phenyl}propane dianhydride, 2,2-bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}propane dianhydride 4,4'-bis[4-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, 4,4'-bis[3-(1,2-dicarboxy)phenoxy]biphenyl dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, bis{4-[3-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl} ketone dianhydride, As the acid dianhydride, a chain aliphatic acid dianhydride such as ethylenetetracarboxylic dianhydride and butanetetracarboxylic dianhydride may be used.

[0099] <Dicarboxylic acid>

[0100] As described above, the polyimide may be a polyamideimide including a dicarboxylic acid-derived structure represented by the general formula (Va). In the preparation of the polyamideimide, a dicarboxylic acid or a dicarboxylic acid derivative is used. Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-biphenyldicarboxylic 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 4,4'-bicyclohexanedicarboxylic acid; and heterocyclic dicarboxylic acids such as 2,5-thiophenedicarboxylic acid and 2,5-furandicarboxylic acid.

[0101] As the dicarboxylic acid derivative, dicarboxylic acid derivatives such as dicarboxylic acid chlorides, dicarboxylic acid esters and dicarboxylic acid anhydrides are used. Among them, dicarboxylic acid chlorides are preferred because of their high reactivity.

[0102] From the viewpoint of solubility of polyamide-imide and compatibility with polyester resin, as dicarboxylic acid, aromatic dicarboxylic acid and alicyclic dicarboxylic acid are preferred, and aromatic dicarboxylic acid is particularly preferred. Among aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, 4,4'-biphenyl dicarboxylic acid, and 4,4'-diphenyl ether dicarboxylic acid are preferred, among which terephthalic acid and isophthalic acid are preferred, and terephthalic acid is particularly preferred.

[0103] <Composition of polyimide>

[0104] As described above, for the polyimide used in the present embodiment, (1) at least one of the diamine component and the acid dianhydride component has a fluorene skeleton, or (2) the diamine component has a fluoroalkyl group and the acid dianhydride component has an ester bond. The preferred compositions of (1) the polyimide having a fluorene skeleton and (2) the polyimide having a fluoroalkyl group and an ester bond are described in detail below.

[0105] (1) The polyimide having a fluorene skeleton may contain both a diamine having a fluorene skeleton and an acid dianhydride having a fluorene skeleton.

[0106] When the diamine component has a fluorene skeleton, the diamine having a fluorene skeleton is preferably 9,9-bis(4-aminophenyl)fluorene. The ratio of the diamine having a fluorene skeleton relative to the total amount of the diamine component of the polyimide is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, and can be 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 100 mol%, and the amount of 9,9-bis(4-aminophenyl)fluorene is preferably within the above range.

[0107] When the polyimide contains a diamine having a fluorene skeleton and a diamine not having a fluorene skeleton as diamine components, the diamine not having a fluorene skeleton is preferably a diamine having a fluoroalkyl group, a diamine having an alicyclic structure, a diamine having an ether structure, a diamine having a sulfonic group, or a diamine having a fluorine-containing group other than a fluoroalkyl group, and among them, a diamine having a fluoroalkyl group such as TFMB is particularly preferred from the viewpoint of solubility and compatibility with a polyester resin. The amount of the diamine not having a fluorene skeleton may be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, or 70 mol% or more relative to the total amount of the diamine component.

[0108] When the diamine component has a fluorene skeleton, it is preferred to include an acid dianhydride having a fluoroalkyl group such as 6FDA as the acid dianhydride component. The ratio of the acid dianhydride having a fluoroalkyl group can be 10 mol% or more, 30 mol% or more, 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol% relative to the total amount of the acid dianhydride component of the polyimide.

[0109] As the acid dianhydride having no fluoroalkyl group, alicyclic tetracarboxylic dianhydride, acid dianhydride having an ether structure, acid dianhydride having a fluorene skeleton, aromatic tetracarboxylic dianhydride, and the like are preferable.

[0110] When the acid dianhydride component has a fluorene skeleton, as the acid dianhydride having a fluorene skeleton, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride is preferably used. Relative to the total amount of the acid dianhydride component of the polyimide, the ratio of the acid dianhydride having a fluorene skeleton is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, and can be 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more or 100 mol%, and the amount of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride is preferably within the above range.

[0111] When the polyimide contains an acid dianhydride having a fluorene skeleton and an acid dianhydride not having a fluorene skeleton as an acid dianhydride component, the acid dianhydride not having a fluorene skeleton is preferably an acid dianhydride having a fluoroalkyl group, an alicyclic tetracarboxylic dianhydride, an acid dianhydride having an ether structure, an acid dianhydride having a fluorene skeleton, an acid dianhydride having an ester bond, and an aromatic tetracarboxylic dianhydride, wherein, from the viewpoint of solubility and compatibility with a polyester resin, an acid dianhydride having a fluoroalkyl group such as 6FDA is particularly preferred. The amount of the acid dianhydride not having a fluorene skeleton can be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, or 70 mol% or more relative to the total amount of the diamine component.

[0112] When the acid dianhydride component has a fluorene skeleton, it is preferred to include a diamine having a fluoroalkyl group such as TFMB as the diamine component. The ratio of the diamine having a fluoroalkyl group to the total amount of the diamine component of the polyimide may be 10 mol% or more, 30 mol% or more, 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%.

[0113] As the diamine not having a fluoroalkyl group, a diamine having an alicyclic structure, a diamine having an ether structure, a diamine having a sulfone group, a diamine having a fluorine-containing group other than a fluoroalkyl group, a diamine having a fluorene skeleton, and the like are preferable.

[0114] In a polyimide having a fluorene skeleton as a diamine component and / or an acid dianhydride component, when the ratio of a diamine having a sulfonic group as a diamine component is high, there is a tendency that the compatibility with the polyester resin deteriorates. Therefore, the ratio of the diamine having a sulfonic group is preferably 20 mol% or less, more preferably 10 mol% or less, and can be 5 mol% or less or 0, relative to the total amount of the diamine component of the polyimide.

[0115] The polyimide with a high ratio of an acid dianhydride component with an ester bond, such as bis(trimellitic anhydride) ester, has a tendency to have poor UV resistance. From the viewpoint of UV resistance, relative to the total amount of the acid dianhydride component of the polyimide, the ratio of the acid dianhydride with an ester bond is preferably 40 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, and can be 5 mol% or less or 0. Even if the polyimide having a fluorene skeleton in which the diamine component and / or the acid dianhydride component do not include an acid dianhydride component with an ester bond, it also shows compatibility with the polyester resin, and is therefore useful from the viewpoint of improving the UV resistance of molded bodies such as resin compositions and films.

[0116] (2) The polyimide having a fluoroalkyl group and an ester bond contains a diamine having a fluoroalkyl group as a diamine component, and the acid dianhydride component contains an acid dianhydride having an ester bond.

[0117] From the viewpoint of solubility of polyimide and compatibility with polyester resin, fluoroalkyl-substituted benzidine such as TFMB is preferred as the diamine having a fluoroalkyl group. The ratio of the diamine having a fluoroalkyl group is preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more, and may be 80 mol% or more, 85 mol% or more, or 90 mol% or more relative to the total amount of diamine components of the polyimide. The amount of fluoroalkyl-substituted benzidine is preferably within the above range, and the amount of TFMB is particularly preferably within the above range.

[0118] When the polyimide contains a diamine having a fluoroalkyl group and a diamine not having a fluoroalkyl group as diamine components, the diamine not having a fluoroalkyl group is preferably a diamine having an alicyclic structure, a diamine having an ether structure, a diamine having a fluorene skeleton, a diamine having a sulfonic group, or a diamine having a fluorine-containing group other than a fluoroalkyl group.

[0119] When the ratio of the diamine having a sulfonic group as the diamine component is high, there is a tendency that the compatibility with the polyester resin deteriorates. Therefore, the ratio of the diamine having a sulfonic group is preferably 20 mol% or less, more preferably 10 mol% or less, and can be 5 mol% or less or 0, relative to the total amount of the diamine components of the polyimide.

[0120] From the viewpoint of solubility of polyimide and compatibility with polyester resin, bis(trimellitic anhydride) ester is preferred as the acid dianhydride with ester bond, wherein TahmbP is particularly preferred. Relative to the total amount of acid dianhydride components of polyimide, the ratio of acid dianhydride with ester bond is preferably 10 mol% or more, more preferably 20 mol% or more, and can be 30 mol% or more, 50 mol% or more, 60 mol% or more or 75 mol% or more. Preferably, the amount of bis(trimellitic anhydride) ester is within the above range, and particularly preferably, the amount of TahmbP is within the above range.

[0121] When the polyimide contains an acid dianhydride having an ester bond and an acid dianhydride without an ester bond as the acid dianhydride component, the acid dianhydride without an ester bond is preferably an acid dianhydride having a fluoroalkyl group, an alicyclic tetracarboxylic dianhydride, an acid dianhydride having an ether structure, or an aromatic tetracarboxylic dianhydride. The total amount of bis(trimellitic anhydride) ester, an acid dianhydride having a fluoroalkyl group, an acid dianhydride having an ether structure, an alicyclic tetracarboxylic dianhydride, and the aforementioned aromatic tetracarboxylic dianhydride is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and can be 95 mol% or more or 100 mol%.

[0122] As described above, (1) the polyimide having a fluorene skeleton and (2) the polyimide having a fluoroalkyl group and an ester bond may be a polyamide-imide comprising a dicarboxylic acid-derived structure represented by the general formula (Va). The amount of the dicarboxylic acid-derived structure in the polyamide-imide may be 10 or more mol parts, 20 or more mol parts, 30 or more mol parts, or 40 or more mol parts relative to 100 mol parts of the structure derived from tetracarboxylic dianhydride represented by the general formula (IIIa). The amount of the dicarboxylic acid-derived structure is preferably 250 or less mol parts, more preferably 200 or less mol parts, and may be 100 or less mol parts, 80 or less mol parts, 60 or less mol parts, or 50 or less mol parts relative to 100 mol parts of the structure derived from tetracarboxylic dianhydride.

[0123] The higher the ratio of the dicarboxylic acid-derived structure of the general formula (Va), that is, the higher the ratio of the amide structure, the higher the solubility of the polyamide-imide in the organic solvent tends to be. On the other hand, if the ratio of the dicarboxylic acid-derived structure is too large, the compatibility with the polyester resin may be reduced, and the heat resistance of the resin composition may be reduced.

[0124] <Preparation of polyimide>

[0125] The polyamic acid as a polyimide precursor is obtained by the reaction of an acid dianhydride and a diamine, and the polyimide is obtained by dehydration of the polyamic acid into a ring (imidization). The preparation method of the polyamic acid is not particularly limited, and all known methods can be applied. For example, a polyamic acid solution is obtained by dissolving a diamine and a tetracarboxylic dianhydride in an organic solvent in an approximate molar amount (a molar ratio of 90:100 to 110:100) and stirring.

[0126] When preparing polyamideimide, dicarboxylic acid or its derivative (diacid chloride, dicarboxylic acid anhydride, etc.) can be used as monomers to prepare polyamideimide on the basis of diamine and tetracarboxylic dianhydride. In this case, the amount of each monomer can be adjusted so that the total amount of tetracarboxylic dianhydride and dicarboxylic acid or its derivative is substantially equal to the molar amount of diamine.

[0127] The concentration of the polyamic acid solution is usually 5 to 35% by weight, preferably 10 to 30% by weight. When the concentration is within this range, the polyamic acid obtained by polymerization has an appropriate molecular weight, and the polyamic acid solution has an appropriate viscosity.

[0128] In the polymerization of polyamic acid, in order to suppress the ring opening of acid dianhydride, it is preferred to add acid dianhydride to diamine. In the case of adding multiple diamines or multiple acid dianhydrides, they can be added at one time or in multiple times. By adjusting the order of adding monomers, various physical properties of polyimide can be controlled.

[0129] The organic solvent used in the polymerization of polyamic acid is not particularly limited as long as it is a solvent that does not react with diamine and acid dianhydride and can dissolve polyamic acid. As an organic solvent, urea solvents such as methyl urea, N, N-dimethylethyl urea, sulfoxides such as dimethyl sulfoxide, diphenyl sulfone, tetramethyl sulfone or sulfone solvents, N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), N, N'-diethylacetamide, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, amide solvents such as hexamethylphosphoryl triamide, chloroform, halogenated alkane solvents such as dichloromethane, aromatic hydrocarbon solvents such as benzene and toluene, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, ether solvents such as methyl paracresol methyl ether can be listed. Usually these solvents are used alone or in combination as needed. From the viewpoint of the solubility and polymerization reactivity of polyamic acid, DMAc, DMF, NMP, etc. are preferably used.

[0130] Polyimide is obtained by dehydration ring formation of polyamic acid. As a method for preparing polyimide from polyamic acid solution, it can be listed as follows: add a dehydrating agent, an imidization catalyst, etc. to a polyamic acid solution, thereby carrying out an imidization method in a solution. In order to promote the progress of imidization, the polyamic acid solution can be heated. By mixing a solution containing a polyimide generated by the imidization of polyamic acid with a poor solvent, the polyimide is precipitated in the form of a solid substance. By separating the polyimide in the form of a solid substance, impurities, residual dehydrating agents and imidization catalysts generated during the synthesis of polyamic acid can be cleaned / removed using a poor solvent, and the coloring of the polyimide, the rise of yellowness, etc. can be prevented. In addition, by separating the polyimide in the form of a solid substance, when preparing a solution for preparing a molded body such as a film, a solvent suitable for thin filmization such as a low boiling point solvent can be applied.

[0131] The molecular weight of the polyimide (weight average molecular weight in terms of polyethylene oxide measured by gel permeation chromatography (GPC)) is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, and further preferably 40,000 to 300,000. When the molecular weight is too small, the strength of the film may be insufficient. When the molecular weight is too large, the compatibility with the polyester resin may be poor and the film forming property may be poor.

[0132] From the viewpoint of thermal stability and light stability of the resin composition and the film, the polyimide preferably has low reactivity. The acid value of the polyimide is preferably 0.4mmol / g or less, more preferably 0.3mmol / g or less, and further preferably 0.2mmol / g or less. The acid value of the polyimide may be 0.1mmol / g or less, 0.05mmol / g or less, or 0.03mmol / g or less. From the viewpoint of the acid value becoming smaller, the polyimide preferably has a high imidization rate. Due to the small acid value, there is a tendency to improve the stability of the polyimide and improve the compatibility with the polyester resin.

[0133] <Polyester resin>

[0134] Polyester resins are condensates of dicarboxylic acids and diols. Polyethylene terephthalate (PET), a representative polyester, is a condensate of ethylene glycol and terephthalic acid, has high crystallinity, and low solubility in organic solvents. In this embodiment, polyester resins soluble in organic solvents are used.

[0135] Examples of the polyester soluble in an organic solvent include components whose crystallinity is reduced or amorphous by using (A) a diol having 4 or more carbon atoms between two hydroxyl groups as a diol component and (B) an aliphatic dicarboxylic acid as a dicarboxylic acid component.

[0136] Examples of the diol having 4 or more carbon atoms between two hydroxyl groups include 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, neopentyl glycol, isosorbide, polycarbonate diol, 4,4'-isopropylidenebis(2-phenoxyethanol), 4,4'-isopropylidenebis(3-phenoxyethanol), and 4,4'-isopropylidenebis(4-phenoxyethanol).

[0137] Among these, from the viewpoint of improving the solubility of the polyester resin, the carbon number between the two hydroxyl groups is preferably 5 or more, and among them, the alkylene group between the two hydroxyl groups is preferably bulky because it has a branched or alicyclic structure.

[0138] As the diol component, a diol having 4 or more carbon atoms between two hydroxyl groups and a diol having 3 or less carbon atoms between two hydroxyl groups can be used in combination. A typical example of the diol having 3 or less carbon atoms between two hydroxyl groups is ethylene glycol, and others include 1,3-propylene glycol and 1,2-propylene glycol.

[0139] The polyester may contain trifunctional or higher functional polyols as a polyol component on the basis of diols, for example, glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, and the like.

[0140] Examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and tetrahydrophthalic acid.

[0141] As the dicarboxylic acid component, an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid may be used in combination. A typical example of the aromatic dicarboxylic acid is terephthalic acid, and other examples thereof include isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and biphenyl dicarboxylic acid.

[0142] In the polymerization of polyester, dicarboxylic acid derivatives such as acid anhydrides can be used as dicarboxylic acid components. Polyesters can contain trifunctional or higher polyacids as acid components, for example: trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, trimellitic acid, ethylene glycol bis (trimellitic anhydride), propylene glycol tris (trimellitic anhydride), 1,2,3,4-butanetetracarboxylic acid, etc. In addition, polyesters can contain fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and other fatty acids, and their ester-forming derivatives; high-boiling monocarboxylic acids such as benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid, and 4-hydroxyphenylstearic acid; high-boiling monohydric alcohols such as stearyl alcohol and 2-phenoxyethanol; hydroxycarboxylic acids such as ε-caprolactone, lactic acid, β-hydroxybutyric acid, and p-hydroxybenzoic acid, etc. as acid components.

[0143] The polymerization method of the polyester is not particularly limited, and various known methods can be employed, such as a method of obtaining an oligomer by an ester exchange reaction method or a direct esterification method and then performing melt polymerization or solid phase polymerization.

[0144] From the viewpoint of heat resistance of the resin composition and the molded body, the glass transition temperature of the polyester resin is preferably -40°C or higher, more preferably 20°C or higher, more preferably 40°C or higher, and may be 60°C or higher, 80°C or higher, or 100°C or higher.

[0145] The weight average molecular weight (polystyrene equivalent) of the polyester resin is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, and may be 5,000 to 40,000 or 10,000 to 30,000 from the viewpoint of solubility in organic solvents, compatibility with the polyimide and strength of the molded product.

[0146] Commercially available products of solvent-soluble polyester resins include "elitel" manufactured by UNITIKA LTD. and "VYLON" manufactured by TOYOBO CO. LTD. More specifically, "elitel" manufactured by UNITIKA LTD. includes model UE3200 (weight average molecular weight 16,000, Tg: 65°C, copolymer of terephthalic acid, isophthalic acid, neopentyl glycol, and ethylene glycol), UE3201 (weight average molecular weight 20,000, Tg: 65°C), UE3203 (weight average molecular weight 20,000, Tg: 60°C), UE3210 (weight average molecular weight 40,000, Tg: 45°C, copolymer of isophthalic acid, adipic acid, neopentyl glycol, and ethylene glycol), UE3215 (weight average molecular weight 20,000, Tg: 60°C), and UE3220 (weight average molecular weight 20,000, Tg: 60°C). UE3216 (weight average molecular weight 16,000, Tg: 45°C), UE3240 (weight average molecular weight 18,000, Tg: 40°C), UE3250 (weight average molecular weight 18,000, Tg: 40°C), UE3500 (weight average molecular weight 30,000, Tg: 35°C), UE3620 (weight average molecular weight 16,000, Tg: 42°C), UE9200 (weight average molecular weight 15,000, Tg: 65°C); TOYOBO CO.LTD. "VYLON" model UR4800 (weight average molecular weight 25,000, Tg: 105°C), UR8300 (weight average molecular weight 30,000, Tg: 23°C), etc.

[0147] <Preparation of resin composition>

[0148] The above-mentioned polyimide is mixed with a polyester resin to prepare a resin composition. The ratio of the polyimide to the polyester resin in the resin composition is not particularly limited. The mixing ratio (weight ratio) of the polyimide to the polyester resin can be 98:2 to 2:98, 95:5 to 10:90 or 90:10 to 15:85. The higher the ratio of the polyimide, the higher the mechanical strength of the molded body such as a film. The higher the ratio of the polyester resin, the less coloring of the molded body such as a film and the higher the transparency.

[0149] In order to fully exert the effect of improving transparency by mixing polyimide and polyester resin, the ratio of polyester resin to the total of polyimide and polyester resin is preferably 10 weight % or more, and can be 15 weight % or more, 20 weight % or more, 25 weight % or more, 30 weight % or more, 35 weight % or more, 40 weight % or more, 45 weight % or more or 50 weight % or more.

[0150] Polyimide is a polymer having a special molecular structure, and generally has low solubility in organic solvents and is not compatible with other polymers. In addition, as described above, polyethylene terephthalate, which is a representative example of polyester resins, has high crystallinity and is not soluble in organic solvents. In this embodiment, by using a polyimide and a polyester resin that are soluble in specific organic solvents, the polyimide and the polyester are highly soluble in organic solvents and are compatible.

[0151] Whether the polyimide and the polyester resin show compatibility in the solution state is confirmed by dissolving the resin composition in dimethylformamide (DMF) at a solid content concentration of 10% by weight. If the DMF solution does not phase separate and is transparent, it is judged that the polyimide and the polyester resin show compatibility in the resin composition. In the case where the DMF solution is separated into two or more phases and becomes turbid, it is judged that the polyimide and the polyester resin do not show compatibility. The haze of the solution containing the polyimide and the polyester resin measured at an optical path length of 1 cm is preferably 10% or less, more preferably 5% or less, further preferably 2% or less, and particularly preferably 1% or less.

[0152] The resin composition comprising polyimide and polyester resin preferably has a single glass transition temperature in a solid state in differential scanning calorimetry (DSC) and / or dynamic viscoelasticity measurement (DMA). When the resin composition has a single glass transition temperature, it can be considered that the polyimide and polyester resin are completely compatible. The molded body comprising polyimide and polyester resin also preferably has a single glass transition temperature.

[0153] The resin composition may be a composition obtained by mixing only the polyimide and the polyester resin separated as solid components, or a composition obtained by kneading the polyimide and the polyester resin. In addition, when the polyimide solution is mixed with a poor solvent to separate the polyimide resin, the polyester resin may be mixed in the solution, so that the resin composition mixed with the polyimide and the polyester resin is separated in the form of a solid substance (powder).

[0154] The resin composition may be a mixed solution containing polyimide and polyester resin. The resin mixing method is not particularly limited, and the resins may be mixed in a solid state or in a liquid to form a mixed solution. A polyimide solution and a polyester resin solution may also be prepared separately and mixed to prepare a mixed solution of polyimide and polyester resin.

[0155] The solvent of the solution containing polyimide and polyester resin is not particularly limited as long as it is a solvent that shows solubility in both polyimide and polyester resin. Examples of the solvent 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 halogenated alkane solvents such as chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, and dichloromethane.

[0156] Generally, polyimide has low solubility in solvents and is often dissolved only in highly polar solvents. Therefore, from the viewpoint of the solubility of polyimide resin and the compatibility of polyimide resin and polyester resin in solution, 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 the removability of solvents during film manufacturing, low-boiling non-amide solvents such as ketone solvents and alkyl halide solvents are preferred.

[0157] The resin composition may be mixed with organic or inorganic low molecular weight compounds, high molecular weight compounds (e.g., epoxy resins), etc. The resin composition may contain flame retardants, ultraviolet absorbers, crosslinking agents, dyes, pigments, surfactants, leveling agents, plasticizers, microparticles, sensitizers, etc. The microparticles include organic microparticles such as polystyrene and polytetrafluoroethylene, inorganic microparticles such as colloidal silica, carbon, and layered silicates, etc., and may be porous or hollow structures. Fiber-reinforced materials include carbon fibers, glass fibers, aramid fibers, etc.

[0158] [Molded articles and films]

[0159] The above composition can be used to form various molded bodies. As molding methods, there can be listed: injection molding, transfer molding, compression molding, blow molding, inflation molding, calendaring molding, melt extrusion molding and other melting methods. Compared with polyimide monomers, the resin composition containing polyimide and polyester resin tends to have a lower melt viscosity, so it is excellent in moldability such as injection molding, transfer molding, compression molding, melt extrusion molding, etc.

[0160] In addition, the solution of the resin composition containing polyimide and polyester resin tends to have a lower solution viscosity than the solution of polyimide monomer with the same solid content concentration. Therefore, the solution has excellent handling properties such as transportation and high coating properties, which is advantageous in reducing uneven thickness of the film.

[0161] In one embodiment, the molded body is a film. The film can be formed by a melting method or a solution method. From the perspective of producing a film with excellent transparency and uniformity, the solution method is preferred. In the solution method, the film is obtained by coating the solution containing the polyimide and the polyester resin on a support and removing the solvent by drying.

[0162] As a method for coating the resin solution on a support, a known method using a rod coater, a comma coater, etc. can be applied. As a support, a glass substrate, a metal substrate such as SUS, a metal roller, a metal belt, a plastic film, etc. can be used. From the viewpoint of improving productivity, as a support, an annular support such as a metal roller, a metal belt, or a long plastic film, etc. is preferably used, and a film is manufactured by roll-to-roll. When a plastic film is used as a support, a material that is insoluble in the solvent of the film-forming coating can be appropriately selected.

[0163] It is preferred to heat the solvent during drying. The heating temperature is not particularly limited as long as it is a temperature that can remove the solvent and suppress the coloring of the obtained film, and can be appropriately set to about room temperature to 250°C, preferably 50°C to 220°C. The heating temperature can be increased in a stepwise manner. In order to improve the removal efficiency of the solvent, after drying to a certain extent, the resin film can be peeled off from the support and dried. In order to promote the removal of the solvent, heating can be performed under reduced pressure.

[0164] The film may be stretched in one direction or in multiple directions for the purpose of improving the mechanical strength of the film. If the film is stretched, the polymer chains are oriented in the stretching direction, so the strength of the film in the in-plane direction is improved, and there is a tendency to suppress the rupture and cracking of the film. In a compatible system of polyimide and polyester resin, as the tensile elastic modulus in the stretching direction increases, there is a tendency to improve the bending resistance.

[0165] For example, a film used as a cover film or substrate material of a foldable display device (foldable display) requires high mechanical strength in a direction perpendicular to the bending axis because the film is repeatedly bent along the bending axis at the same position. Therefore, by arranging the stretching direction of the film to be perpendicular to the bending axis, a device with high bending resistance can be provided in which the film is unlikely to break or crack at the bending position even if it is repeatedly bent.

[0166] The stretching conditions of the film are not particularly limited. For example, the stretching temperature is about ±40°C of the glass transition temperature of the film, and can be about 120 to 300°C, 150 to 250°C, or 180 to 230°C. The stretching ratio is about 1 to 200%, and can be 5 to 150%, 10 to 120%, or 20 to 100%. The larger the stretching ratio, the greater the tendency of the tensile elastic modulus in the stretching direction. On the other hand, when the stretching ratio is too large, there is a tendency for the mechanical strength in the direction orthogonal to the stretching direction to decrease, and sometimes the handleability of the film is reduced.

[0167] From the viewpoint of improving the strength in any direction within the plane, the film can be biaxially stretched. Biaxial stretching can be simultaneous biaxial stretching or sequential biaxial stretching. In biaxial stretching, the stretching ratio in one direction can be the same as or different from the stretching ratio in the orthogonal direction. If a difference is set for the stretching ratio, there is a tendency for the mechanical strength in the direction with a large stretching ratio to become relatively large. In the case of using a biaxially stretched film with anisotropic stretching ratio for a foldable device, it is preferably configured in a manner that the direction with a large stretching ratio is orthogonal to the bending axis.

[0168] The thickness of the film is not particularly limited and can be appropriately set according to the purpose. The thickness of the film is, for example, 5 to 300 μm. From the viewpoint of manufacturing a film that is both self-supporting and flexible and has high transparency, the thickness of the film is preferably 20 μm to 200 μm, and can be 30 μm to 150 μm, 40 μm to 100 μm, or 50 μm to 80 μm. The thickness of the film used as a cover film for a display is preferably 10 μm or more. In the case of a stretched film, the thickness after stretching is preferably in the above range.

[0169] The haze of the film is preferably 10% or less, more preferably 5% or less, further preferably 4% or less, and can be 3.5% or less, 3% or less, 2% or less, or 1% or less. The haze of the film is preferably low. As described above, polyimide and polyester resin show compatibility, so a film with low haze and high transparency is obtained. For a resin composition mixed with polyimide and polyester resin, the haze when manufacturing a film with a thickness of 10 μm is preferably 10% or less.

[0170] The total light transmittance of the film is preferably 85% or more, preferably 90% or more. The total light transmittance of the resin composition containing a mixture of polyimide and polyester resin when a film having a thickness of 10 μm is produced is preferably 85% or more.

[0171] The yellowness index (YI) of the film is preferably 5.0 or less, and can be 4.0 or less, 3.0 or less, 2.0 or less, 1.5 or less, or 1.0 or less. For the resin composition mixed with polyimide and polyester resin, the yellowness index when manufacturing a film with a thickness of 10 μm is preferably 5.0 or less. As described above, by mixing polyimide and polyester resin, a film with less coloring and a small YI is obtained compared with the case of using polyimide alone.

[0172] From the viewpoint of strength, the tensile modulus of the film at room temperature is preferably 2.0 GPa or more, more preferably 3.0 GPa or more. As described above, 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 more, 5.0 GPa or more, 5.5 GPa or more, 6.0 GPa or more, 6.5 GPa or more, or 7.0 GPa or more. The pencil hardness of the film is preferably 6B or more, preferably 4B or more, and can be 2B or more, F or more, or 2H or more. In the compatible system of polyimide and polyester resin, it is difficult to reduce the pencil hardness even if the ratio of polyester resin is increased. Therefore, a film with excellent mechanical strength peculiar to polyimide, less coloring and excellent transparency can be provided without significantly reducing it.

[0173] From the viewpoint of heat resistance, the tensile modulus of the film at 150° C. is preferably 1.0 MPa or more, more preferably 10.0 MPa or more, and further preferably 100 MPa or more. A high elastic modulus at high temperatures is preferred because deformation of the molded article is small under high temperature environments and long-term use environments.

[0174] The film formed by the resin composition containing polyimide and polyester resin has little coloration and high transparency, and is therefore suitable for use as a display material. In particular, the film with high mechanical strength can be applied to surface components such as cover windows of displays. When the film of the present invention is actually used, an antistatic layer, an easy-adhesion layer, a hard coating layer, an antireflection layer, etc. can be provided on the surface.

[0175] Example

[0176] Hereinafter, the embodiments of the present invention will be described in more detail with reference to Examples. It should be noted that the present invention is not limited to the following Examples.

[0177] [Preparation of polyimide resin]

[0178] Dimethylformamide (DMF) was added to a removable flask and stirred under a nitrogen atmosphere. Diamine and tetracarboxylic dianhydride were added thereto at the ratio (mol %) shown in Table 1, and acetic acid was further added, and the mixture was stirred for 5 to 10 hours under a nitrogen atmosphere to react to obtain a polyamic acid solution having a solid content concentration of 13% by weight. Pyridine was added to the polyamic acid solution as an imidization catalyst, and after it was completely dispersed, acetic anhydride was added and stirred at 90°C for 3 hours. After cooling to room temperature, 2-propanol (IPA) was added dropwise while stirring the solution to precipitate a polyimide resin. After further adding IPA and stirring for about 30 minutes, suction filtration was performed using a Kiriyama funnel. After washing the obtained solid with IPA, it was dried in a vacuum oven set at 120°C for 12 hours to obtain a polyimide resin.

[0179] [Preparation of polyamide-imide resin]

[0180] Dimethylacetamide (DMAc) was added to a detachable flask and stirred under a nitrogen atmosphere. Diamine, tetracarboxylic dianhydride and acid chloride were added thereto at the ratio (mol %) shown in Table 2, and stirred for 5 to 10 hours under a nitrogen atmosphere to react to obtain a polyamic acid solution having a solid content concentration of 9 wt %. Thereafter, imidization, resin precipitation, washing and drying were performed in the same manner as in the preparation of polyimide resin to obtain a polyamide-imide resin.

[0181] [Reference Example: Production of polyimide film]

[0182] The polyimide or polyamide-imide resin is dissolved in DMF to prepare a DMF solution having a solid content of 10 wt%. The solution is applied to an alkali-free glass plate, and heated and dried under the conditions of 15 minutes at 60° C., 30 minutes at 150° C., and 15 minutes at 200° C. in an atmospheric atmosphere to produce a film-coated glass plate having a film having a thickness of about 10 μm laminated on the glass plate.

[0183] [Examples 1 to 17 and Comparative Examples 1 to 15: Preparation of resin compositions and production of films]

[0184] The above-mentioned polyimide or polyamide-imide resin and a solvent-soluble polyester resin ("elitel UE-3200G" manufactured by UNITIKA LTD., glass transition temperature: 65°C, a copolymer of terephthalic acid, isophthalic acid, neopentyl glycol and ethylene glycol; hereinafter "Polyester 1") were dissolved in DMF at a weight ratio of 1:1 to prepare a DMF solution having a solid content of 10% by weight, and a film having a thickness of about 10 μm was prepared in the same manner as above. It should be noted that in Example 2, as the polyester resin, an amorphous polyester resin having a glass transition temperature of 75°C, which is a copolymer of terephthalic acid, isophthalic acid, 4,4'-isopropylidenebis(2-phenoxyethanol) and ethylene glycol; hereinafter "Polyester 2") was used instead of Polyester 1.

[0185] [Evaluation of transparency]

[0186] The film-coated glass obtained by laminating the films having a thickness of about 10 μm obtained in the examples and comparative examples was used as the measurement sample. The haze and total light transmittance (TT) were measured using a haze meter "HZ-V3" manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K7136 and JIS K7361-1, and the yellowness (YI) was measured using a spectrophotometer "SC-P" manufactured by Suga Test Instruments Co., Ltd. in accordance with JIS K7373.

[0187] [Evaluation results]

[0188] The resin compositions (compositions of polyimide and types of polyester resin) and film evaluation results of Examples 1 to 13 and Comparative Examples 1 to 10 are shown in Table 1. The resin compositions (compositions of polyamide-imide and types of polyester resin) and film evaluation results of Examples 14 to 17 and Comparative Examples 11 to 15 are shown in Table 2. Tables 1 and 2 summarize the measurement results of the total light transmittance of the films of the reference examples, which were produced using the same polyimide resin and polyamide-imide resin as used in the examples.

[0189] In Tables 1 and 2, the compounds are described using the following abbreviations.

[0190] <Tetracarboxylic dianhydride>

[0191] TAAMBP: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester

[0192] BP-TME: Bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid)-biphenyl-4,4'-diyl ester BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride

[0193] 6FDA: 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride

[0194] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0195] PMDA: Pyromellitic anhydride

[0196] ODPA: 4,4'-oxydiphthalic anhydride

[0197] CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

[0198] H-PMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride

[0199] H-BPDA: 1,1'-bicyclohexane-3,3',4,4'-tetracarboxylic acid-3,4:3',4'-dianhydride

[0200] <Diacyl chloride>

[0201] TPC: Terephthaloyl chloride

[0202] BPC: 4,4'-biphenyl dichloride

[0203] <Diamine>

[0204] TFMB: 2,2'-bis(trifluoromethyl)benzidine

[0205] BAFL: 9,9-bis(4-aminophenyl)fluorene

[0206] DDS: 3,3'-Diaminodiphenyl sulfone

[0207] ISO: Isophorone diamine

[0208] BAMC: 1,3-bis(aminomethyl)cyclohexane

[0209] BAMN: bis(aminomethyl)norbornane

[0210] [Table 1]

[0211]

[0212] [Table 2]

[0213]

[0214] The alloy films of polyimide and polyester resin of Examples 1 to 13 showed a higher total light transmittance (TT) than the polyimide film of the reference example (PI only) produced using only polyimide. The alloy films of polyamideimide and polyester resin of Examples 14 to 17 also showed a higher total light transmittance (TT) than the film of the reference example produced using only polyamideimide.

[0215] In Comparative Examples 1 to 10, the compatibility between polyimide and polyester resin was insufficient, so the haze of the film was high and the transparency was insufficient. In Comparative Examples 11 to 15, the compatibility between polyamide-imide and polyester resin was insufficient, so the haze of the film was high and the transparency was insufficient. It should be noted that in these comparative examples, the total light transmittance could not be accurately measured due to the high haze, so the measured value of the total light transmittance was not recorded.

[0216] The above results show that the polyimide having a specific composition is compatible with the solvent-soluble polyester resin, and a highly transparent film can be obtained by mixing the polyimide and the polyester resin.

Claims

1. A resin composition comprising a solvent-soluble polyimide and a solvent-soluble polyester resin, The polyester resin has a condensation structure of a dicarboxylic acid component and a diol component and satisfies at least one of the following (A) and (B): (A) containing a diol having 4 or more carbon atoms between two hydroxyl groups as a diol component; (B) contains an aliphatic dicarboxylic acid as a dicarboxylic acid component, The polyimide has a diamine-derived structure represented by the general formula (IIa) and a tetracarboxylic dianhydride-derived structure represented by the general formula (IIIa). Y is a diamine residue as a divalent organic group, X is a tetracarboxylic dianhydride residue as a tetravalent organic group, The polyimide satisfies at least one of the following (1) and (2): (1) at least one of the structure derived from diamine and the structure derived from tetracarboxylic dianhydride has a fluorene skeleton; (2) The structure derived from diamine has a fluoroalkyl group, and the structure derived from tetracarboxylic dianhydride has an ester bond.

2. The resin composition according to claim 1, wherein The polyimide includes a structure derived from a diamine having a fluoroalkyl group as the structure derived from the diamine, and includes a structure derived from a tetracarboxylic dianhydride having a fluorene skeleton as the structure derived from the tetracarboxylic dianhydride.

3. The resin composition according to claim 1 or 2, wherein In the polyimide, a ratio of the structure derived from tetracarboxylic dianhydride having a fluorene skeleton is 20 mol% or more relative to the total amount of the structure derived from tetracarboxylic dianhydride.

4. The resin composition according to claim 1, wherein The polyimide includes a structure derived from a diamine having a fluorene skeleton as the structure derived from a diamine, and includes a structure derived from a tetracarboxylic dianhydride having a fluoroalkyl group as the structure derived from a tetracarboxylic dianhydride.

5. The resin composition according to claim 1 or 4, wherein In the polyimide, a ratio of the structure derived from the diamine having a fluorene skeleton is 20 mol% or more relative to the total amount of the structure derived from the diamine.

6. The resin composition according to claim 1, wherein The polyimide includes a structure derived from a diamine having a fluoroalkyl group as the structure derived from a diamine, The diamine having a fluoroalkyl group is a fluoroalkyl-substituted benzidine.

7. The resin composition according to claim 6, wherein The fluoroalkyl-substituted benzidine is 2,2'-bis(trifluoromethyl)benzidine.

8. The resin composition according to any one of claims 1, 2, 4, 6 and 7, wherein In the polyimide, a ratio of the structure derived from the diamine having a fluoroalkyl group is 20 mol% or more relative to the total amount of the structure derived from the diamine.

9. The resin composition according to any one of claims 1, 6 and 7, wherein The polyimide includes a structure derived from tetracarboxylic dianhydride having an ester bond as the structure derived from tetracarboxylic dianhydride, and the tetracarboxylic dianhydride having an ester bond is a bis(trimellitic anhydride) ester.

10. The resin composition according to claim 9, comprising a compound represented by general formula (1) as the bis(trimellitic anhydride) ester: Q in the general formula (1) is an arbitrary divalent organic group. Carboxyl groups are bonded to carbon atoms of Q at both ends of Q, and the carbon atoms bonded to the carboxyl groups may form a ring structure.

11. The resin composition according to claim 9, comprising a compound represented by formula (3) as the bis(trimellitic anhydride) ester, 12. The resin composition according to claim 9, wherein In the polyimide, a ratio of a structure derived from bis(trimellitic anhydride) ester is 10 mol% or more relative to the total amount of the structure derived from tetracarboxylic dianhydride.

13. The resin composition according to any one of claims 1, 2, 4, 6 and 7, wherein The polyimide further comprises a dicarboxylic acid-derived structure represented by the general formula (Va): Z is a dicarboxylic acid residue which is a divalent organic group.

14. The resin composition according to any one of claims 1, 2, 4, 6 and 7, wherein The polyimide and the polyester-based resin are contained in a weight ratio within a range of 98:2 to 2:

98. 15 . A molded body comprising the resin composition according to claim 1 . 16 . A film comprising the resin composition according to claim 1 .

17. The film according to claim 16, which has a total light transmittance of 85% or more, a haze of 10% or less, and a yellowness of 5.0 or less.

Images