Polyimide, resin composition, polyimide film, and method for manufacturing the same

Abstract

Provided is a resin composition including: a polyamide acid-imide copolymer containing a structural unit L represented by the following general formula (1) and having a structure represented by the following general formula (A-1) as X2 in general formula (1); an organic solvent; and, at least one imidization catalyst selected from the group consisting of pyridine, triethylamine, 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, benzimidazole, and N-tert-butoxycarbonylimidazole (N-Boc-imidazole).{In the formula, X1 to X4, n, m, l, R1 to R2, a to b, and * are as defined in the specification}.

Description

Technical Field

[0001] The present invention relates to polyamic acid-imide and resin compositions comprising the same, polyimide resin films, resin films and methods thereof, used, for example, in manufacturing substrates for flexible devices. Background Technology

[0002] Polyimide resin films are typically used as resin films in applications requiring high heat resistance. Conventional polyimide resins are high-heat-resistant resins manufactured by solution polymerization of an aromatic carboxylic acid dianhydride and an aromatic diamine to produce a polyimide precursor, followed by thermal imidization at high temperatures or chemical imidization using a catalyst.

[0003] Polyimide resin is an insoluble, infusible, and ultra-heat-resistant resin with excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low-temperature resistance, and chemical resistance. Therefore, polyimide resin is used in a wide range of fields, including electronic materials. Examples of applications of polyimide resin in electronic materials include insulating coating materials, insulating films, semiconductors, and electrode protective films for thin-film transistor liquid crystal displays (TFT-LCDs). Recently, research has also been conducted on using lightweight and flexible polyimide resin as a flexible substrate to replace the glass substrates previously used in display materials.

[0004] When polyimide resin is used as a flexible substrate, a widely used process involves coating a varnish containing polyimide resin or its precursor and other components onto a suitable support such as a glass substrate, drying it to form a thin film, forming components, circuits, etc. on the film, and then peeling the film off the glass substrate. However, when manufacturing laminates containing polyimide resin, heat treatment at temperatures above 250°C is performed to dry and imidize the polyimide precursor. This heat treatment causes residual stress in the laminate, leading to serious problems such as warping and peeling. This is because polyimide has a larger coefficient of linear expansion than the material constituting the support.

[0005] To reduce residual stress in the aforementioned laminates, the use of polyimide resins with a coefficient of thermal expansion as low as that of glass is being investigated. As a polyimide material with a low coefficient of thermal expansion, polyimides formed from 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA) and p-phenylenediamine are most well-known. It has been reported that, although dependent on film thickness and manufacturing conditions, this polyimide exhibits a very low coefficient of linear thermal expansion (Non-Patent Literature 1).

[0006] However, conventional polyimide resins, including those described in the aforementioned literature, are colored brown or yellow due to their high electron density, resulting in low transmittance in the visible light region. Therefore, it is difficult to achieve a low yellowness (YI value) sufficient for applications requiring transparency. Furthermore, polyimides with low coefficients of linear expansion are known to have high molecular orientation, making laminates prone to turbidity and fogging, thus contributing to deterioration of transmittance (Patent Document 2).

[0007] Generally, regarding yellowness (YI value), it is known that polyimides that are solvent-soluble, for example, using a diamine containing trifluoromethyl groups or polyimides that use alicyclic tetracarboxylic dianhydrides or diamines, exhibit extremely low yellowness (YI value) and residual stress (Patent Documents 3 and 4).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2005 / 113647

[0011] Patent Document 2: Japanese Patent No. 6443579

[0012] Patent Document 3: International Publication No. 2019 / 211972

[0013] Patent Document 4: International Publication No. 2020 / 138360

[0014] Patent Document 5: Japanese Patent No. 4303623

[0015] Patent Document 6: Japanese Patent No. 5595381

[0016] Patent Document 7: Japanese Patent No. 6073528

[0017] Patent Document 8: Japanese Patent Application Publication No. 63-101424

[0018] Patent Document 9: Japanese Patent Application Publication No. 63-110219

[0019] Non-patent literature

[0020] Non-patent document 1: "Latest Polyimide-Basic Application-", compiled by the Japan Polyimide Research Association Summary of the Invention

[0021] The problem the invention aims to solve

[0022] As mentioned above, in order to use polyimide resins as colorless and transparent flexible substrates, it is necessary to balance the seemingly contradictory properties of excellent thermal properties and transparency. In particular, recently, with the shift of TFT device types to LTPS (low-temperature polycrystalline silicon), there is a desire to develop polyimide resins that also exhibit excellent transparency over thermal processes exceeding previous levels.

[0023] While the polyimide resin described in Patent Document 1, a conventional polyimide, exhibits a low coefficient of linear thermal expansion, its transparency is insufficient when used in LTPS processes at temperatures above 400°C. Furthermore, although the polyimide described in Patent Document 2 is reported to have excellent coefficient of linear thermal expansion (CTE) and transparency due to the use of specific tetracarboxylic dianhydride and diamine, the laminate exhibits turbidity and fogging during heating above 400°C, resulting in insufficient haze (HAZE value) when used as a transparent substrate.

[0024] Furthermore, as a known technical concept, methods for achieving transparency are known to include: using alicyclic dianhydrides or diamines without aromatic rings, as described in Patent Document 3; or using diamines with large functional groups that can cause intramolecular distortion (e.g., 2,2'-bis(trifluoromethyl)benzidine, hereinafter also referred to as TFMB), thereby suppressing intramolecular charge transfer (CT) transitions. However, these polyimides with excellent transparency do not have sufficient heat resistance and thermal properties in the polyamic acid state. To obtain high transparency, it is necessary to obtain a solvent-soluble polyimide resin that has undergone imidization during solution polymerization. However, these polyimides have a large coefficient of linear expansion when made into films, lack thermal stability in high-temperature regions above 430°C, and their solubility in solvents is not sufficient.

[0025] To balance these opposing properties, heat-sensitive characteristics, and transparency, the mixing or copolymerization of polyimide and polyamic acid has been studied. However, it is known that even simple mixing of these resins results in phase separation during molding, making them unsuitable as transparent substrates (Patent Document 5). This is believed to be because heat-resistant polyimide has high planarity and a rigid skeleton, making it difficult to be compatible with soluble polyimide with flexible groups during film formation, leading to phase separation.

[0026] Patent Document 4 discloses that by locally coexisting imide and amide structures within the molecule, storage stability and molding processability can be improved. However, the present inventors have confirmed that the polyamic acid-imide resin composition described in Patent Document 4 lacks heat resistance, and its yellowness (YI value) and haze significantly deteriorate during the thermal process of LTPS at temperatures above 430°C. The main reason for this is that since the monomer skeletons of polyimide and polyamic acid are common, a higher ratio of common monomer skeletons between polyimide and polyamic acid can better suppress the generation of haze caused by phase separation, but on the other hand, it is difficult to achieve a balance between the opposing properties of thermal properties and transparency.

[0027] Furthermore, Patent Document 6 discloses that by locally coexisting imide and ammonium acid structures within the molecule and using an alicyclic diamine, flexural strength and transparency can be improved. However, the present inventors have confirmed that the block polyimide described in Patent Document 6 exhibits significantly deteriorated yellowness (YI value) and haze during the LTPS process at temperatures above 430°C. The main reason for this is that, while alicyclic diamines offer excellent flexural strength, they decompose during thermal processes above 430°C, making it difficult to achieve a balance between heat resistance and flexural strength.

[0028] Furthermore, conventional polyimide resins, including the polyimides described in the aforementioned patent documents 7 to 9, are colored brown or yellow due to their high electron density, resulting in low light transmittance in the visible light region, making them unsuitable for applications requiring transparency.

[0029] It has also been learned that when using conventional resin compositions to form polyimide resin films, the resin composition does not flow sufficiently during the curing process (heating to about 400°C), resulting in insufficient in-plane uniformity of the polyimide resin film in terms of film thickness.

[0030] Therefore, conventional polyimide resin films do not meet the required characteristics, such as in-plane uniformity of film thickness and yellowness (YI value), when used as colorless transparent substrates for displays.

[0031] The present invention was made in view of the above-mentioned situation and in order to solve the aforementioned problems. The object is to provide a polyamic acid-imide copolymer resin composition that balances transparency and heat resistance by block copolymerizing a polyamic acid with excellent thermal properties, in which an aromatic ester diamine is used as the main component, with a polyimide with excellent transparency; or, by block copolymerizing a polyimide with excellent bending resistance and transparency with a polyamic acid with excellent heat resistance, a polyamic acid-imide copolymer resin composition that balances transparency and heat resistance, and further balances bending resistance. The polyimide or polyimide copolymer thereof; or, a resin composition comprising a polyamic acid or a polyamic acid-imide copolymer using 4-aminobenzoic acid-3-fluorophenyl ester (APAB) capable of reducing defects in the polyimide film during infrared (IR) curing; or, a resin composition or polyimide resin film capable of obtaining a polyimide resin film with excellent in-plane uniformity of film thickness and low yellowness (YI value); and, methods for manufacturing them or methods for manufacturing displays, laminates and flexible devices.

[0032] Solution for solving the problem

[0033] To address the aforementioned issues, the inventors conducted in-depth research and repeated experiments. The results showed that polyimide films obtained by curing a resin composition containing a polyamic acid-imide copolymer with a specific structure exhibit excellent transparency, haze, heat resistance, and coefficient of linear expansion, as well as low residual stress and flexural strength, or reduced defects in polyimide films cured by infrared (IR). Furthermore, by including an aprotic polar substance with a boiling point of 250°C to 350°C in the resin composition, the resin becomes soft and fluid, improving the in-plane uniformity of film thickness and reducing YI when producing polyimide resin films. Based on these insights, the present invention was completed. That is, the invention is as follows.

[0034] <1>

[0035] A resin composition characterized in that it comprises: a polyamic acid-imide copolymer containing structural units of the following general formula (1), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is at least one selected from the group consisting of imidazole compounds, pyridine compounds, and tertiary amine compounds.

[0036]

[0037] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, n, m, and l are positive integers, and...

[0038] As X2 in the above general formula (1), it includes the structure shown in the following general formula (A-1).

[0039]

[0040] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents the bonding part)}.

[0041] <2>

[0042] According to the resin composition of Project 1, wherein the imidazole compound is at least one selected from the group consisting of 1-methylimidazolium, N-tert-butoxycarbonylimidazolium (N-Boc-imidazolium), 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, 2-ethyl-4-methylimidazolium, 4-ethyl-2-methylimidazolium, 4-methyl-2-phenylimidazolium, 2-undecylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1H-imidazolium, and 1,2-dimethylimidazolium.

[0043] The aforementioned pyridine compound is at least one selected from the group consisting of 4-dimethylaminopyridine, 2,2'-bipyridine, nicotinic acid, isoquinoline, pyridine, and 2-methylpyridine, and / or

[0044] The aforementioned tertiary amine compound is at least one selected from the group consisting of 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, and triethylamine.

[0045] <3>

[0046] The resin composition according to item 1 or 2, wherein the imidization catalyst described above (e) is the imidazole compound described above.

[0047] <4>

[0048] The resin composition according to any one of items 1 to 3, wherein the content of the imidization catalyst (e) is 5 parts by mass or more relative to 100 parts by mass of the polyamic acid-imide copolymer.

[0049] <5>

[0050] A resin composition comprising: a polyamic acid-imide copolymer containing structural units of the following general formula (1) and (d) an organic solvent, wherein the polyamic acid-imide copolymer has a weight-average molecular weight of 170,000 or more.

[0051]

[0052] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, n, m, and l are positive integers, and...

[0053] As X2 in the above general formula (1), it includes the structure shown in the following general formula (A-1).

[0054]

[0055] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents the bonding part)}.

[0056] <6>

[0057] The resin composition according to any one of items 1 to 4, wherein the weight-average molecular weight of the polyamic acid-imide copolymer is 170,000 or more.

[0058] <7>

[0059] A resin composition comprising: a polyamic acid containing a structural unit of the following general formula (3), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is at least one selected from the group consisting of 1-methylimidazolium, N-tert-butoxycarbonylimidazolium (N-Boc-imidazolium), 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, 2-ethyl-4-methylimidazolium, 4-ethyl-2-methylimidazolium, 4-methyl-2-phenylimidazolium, 2-undecylimidazolium, 1-benzyl-2-methylimidazolium, 1H-imidazolium, 4-dimethylaminopyridine, 2,2'-bipyridine, nicotinic acid, isoquinoline, pyridine, 2-methylpyridine, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, and triethylamine.

[0060]

[0061] In the formula, X1 represents a tetravalent organic group, X2 represents a divalent organic group, and n is a positive integer.

[0062] As X2 in the above general formula (3), it includes the structure shown in the following general formula (A-1).

[0063]

[0064] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents the bonding part)}.

[0065] <8>

[0066] A resin composition comprising: a polyamic acid containing a structural unit of the following general formula (3), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is an imidazole compound, and the content of the (e) imidization catalyst is 5 parts by mass or more relative to 100 parts by mass of the polyamic acid.

[0067]

[0068] In the formula, X1 represents a tetravalent organic group, X2 represents a divalent organic group, and n is a positive integer.

[0069] As X2 in the above general formula (3), it includes the structure shown in the following general formula (A-1).

[0070]

[0071] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents the bonding part)}.

[0072] <9>

[0073] A resin composition comprising: a polyamic acid containing a structural unit of the following general formula (3), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is an imidazole compound, and the polyamic acid has a weight-average molecular weight of 170,000 or more.

[0074]

[0075] In the formula, X1 represents a tetravalent organic group, X2 represents a divalent organic group, and n is a positive integer.

[0076] As X2 in the above general formula (3), it includes the structure shown in the following general formula (A-1).

[0077]

[0078] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents the bonding part)}.

[0079] <10>

[0080] The resin composition according to item 7 or 8, wherein the weight-average molecular weight of the polyamic acid is 170,000 or more.

[0081] <11>

[0082] The resin composition according to any one of items 1 to 10, wherein the content of the imidization catalyst (e) is 10 parts by mass or more relative to 100 parts by mass of the polyamic acid-imide copolymer or 100 parts by mass of the polyamic acid.

[0083] <12>

[0084] The resin composition according to any one of items 1 to 11, wherein the imidization catalyst described above (e) is an imidazole compound comprising N-tert-butoxycarbonyl imidazole (N-Boc-imidazole) and / or 1-methylimidazole.

[0085] <13>

[0086] The resin composition according to any one of items 1 to 12, wherein the weight average molecular weight of the polyamic acid-imide copolymer or the polyamic acid is 220,000 or more.

[0087] <14>

[0088] The resin composition according to any one of items 1 to 13 further comprises an aprotic polar substance having a boiling point of 250°C to 350°C.

[0089] <15>

[0090] According to the resin composition of Project 14, the aforementioned aprotic polar substance is sulfolane.

[0091] <16>

[0092] According to any one of items 1 to 15, in the resin composition, X4 in general formula (1) or X2 in general formula (3) is at least one selected from the group consisting of the structures shown in general formula (A-4), general formula (A-5) and general formula (A-6).

[0093]

[0094] In the formula, R8~R 11 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4, Z2 represents a linking group, and * represents a bonding part.

[0095]

[0096] In the formula, R 12 and R 13 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * represents the bonding part.

[0097]

[0098] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and ο are each an integer from 0 to 4, and * represents the bonding part.

[0099] <17>

[0100] According to any one of items 1 to 6 and 11 to 16, the resin composition wherein X3 in the above general formula (1) is selected from at least one of the following general formula (A-3), a structure derived from 4,4'-oxyphthalic anhydride (ODPA), a structure derived from 4,4'-(hexafluoroisopropyl)phthalic anhydride (6FDA), a structure derived from biphenyl tetracarboxylic acid dianhydride (BPDA), and a structure derived from 4,4'-biphenyl bis(triphenyl phthalate monoester anhydride) (TAHQ).

[0101]

[0102] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}.

[0103] <18>

[0104] The resin composition according to any one of items 1 to 6 and 11 to 17, wherein the content of the imidization catalyst (e) is in the range of 0.02 to 0.15 mol% relative to 1 mole of the repeating unit of the polyamic acid-imide copolymer.

[0105] <19>

[0106] A polyamic acid-imide copolymer, characterized in that it comprises the structural unit L represented by the following general formula (1),

[0107]

[0108] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n, m, and l are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M.

[0109] When X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate, it does not include the following components 1 and 2:

[0110] 1. When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), X2 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and

[0111] 2.X3 is a group derived from norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2”-norcamphene-5,5”,6,6”-tetracarboxylic acid dianhydride.

[0112] and,

[0113] As described above, X2 has the structure shown in the following general formula (A-1) or the following general formula (A-2).

[0114]

[0115] {In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b are each independent integers from 0 to 4, and * represents the bonding part}

[0116]

[0117] {In the formula, R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, and c is an integer from 0 to 4. * indicates a bonding part}.

[0118] <20>

[0119] According to the polyamic acid-imide copolymer of Project 19, wherein X3 in the above general formula (1) is selected from at least one of the following general formula (A-3), a structure derived from 4,4'-oxyphthalic anhydride (ODPA), and a structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0120]

[0121] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}.

[0122] <21>

[0123] According to the polyamic acid-imide copolymer of item 19 or 20, wherein X4 in the above general formula (1) is selected from at least one of the structures shown in the following general formulas (A-4), (A-5), and (A-6).

[0124]

[0125] In the formula, R8~R 11 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4, Z2 represents a linking group, and * represents a bonding part.

[0126]

[0127] In the formula, R 12 and R 13 Each of the above-mentioned groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * denotes a bonding part, except where X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF) and the above-mentioned general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone.

[0128]

[0129] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and ο are each an integer from 0 to 4, and * represents the bonding part.

[0130] <22>

[0131] A polyamic acid-imide copolymer, characterized in that it comprises the structural unit L represented by the following general formula (1),

[0132]

[0133] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n, m, and l are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M.

[0134] X4 does not include groups derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine.

[0135] and,

[0136] As described above, X3 comprises at least one structure selected from the group consisting of the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0137]

[0138] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}.

[0139] <23>

[0140] According to the polyamic acid-imide copolymer of Project 22, wherein X4 in the above general formula (1) is selected from at least one of the structures shown in the following general formulas (A-4), (A-5), and (A-6).

[0141]

[0142] In the formula, R8~R 11 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4, Z2 represents a linking group, and * represents a bonding part.

[0143]

[0144] In the formula, R 12 and R 13 Each of the above-mentioned groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, i and j are each independently integers from 0 to 4, and * represents a bonding part, except when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF) and the above-mentioned general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone.

[0145]

[0146] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and ο are each an integer from 0 to 4, and * represents the bonding part.

[0147] <24>

[0148] According to any one of items 19 to 23, the polyamic acid-imide copolymer, wherein the diamine component constituting X2 in the above general formula (1) is different from the diamine composition or diamine type constituting X4.

[0149] <25>

[0150] According to any one of items 19 to 24, the polyamic acid-imide copolymer, wherein X1 in the above general formula (1) is selected from at least one of the following groups: a structure derived from biphenyl tetracarboxylic acid dianhydride (BPDA), a structure derived from 4,4'-oxophthalic acid dianhydride (ODPA), and a structure derived from 4,4'-biphenyl bis(triphenyl ester anhydride) (TAHQ).

[0151] <26>

[0152] The polyamic acid-imide copolymer according to any one of items 19 to 25, wherein the molar ratio (X2 / X1) of X2 to X1 contained in the above general formula (1) is 0.84 to 1.00, and the molar ratio (X4 / X3) of X4 to X3 contained in the above general formula (1) is 1.01 to 2.00.

[0153] <27>

[0154] According to any one of items 19 to 26, the polyamic acid-imide copolymer, wherein the molar ratio (number of moles of structural unit N of the polyamic acid composed of X1 and X2 to the molar ratio (number of moles of structural unit N: number of moles of structural unit M of the polyimide composed of X3 and X4) of the above general formula (1) is in the range of 60:40 to 95:5.

[0155] <28>

[0156] A resin composition comprising, as described in any one of items 19 to 27, a polyamic acid-imide copolymer and (d) an organic solvent.

[0157] <29>

[0158] According to the resin composition of Project 28, the ratio of polyamic acid structural units N composed of X1 and X2 in all polymers contained in the resin composition is 60 to 95 mol%.

[0159] <30>

[0160] The resin composition according to item 28 or 29 further comprises (e) an imidization catalyst.

[0161] <31>

[0162] A polyimide copolymer, characterized in that it comprises structural units represented by the following general formula (2),

[0163]

[0164] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n and m are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M.

[0165] When X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate, it does not include the following components 1 and 2:

[0166] 1. When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), X2 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and

[0167] 2.X3 is a group derived from norcamphene-2-spiro-α-cyclopentanone α-α'-spiro-2”-norcamphene-5,5”,6,6”-tetracarboxylic acid dianhydride.

[0168] and,

[0169] As described above, X2 has the structure shown in the following general formula (A-1) or the following general formula (A-2).

[0170]

[0171] {In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b are each independent integers from 0 to 4, and * represents the bonding part}

[0172]

[0173] {In the formula, R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, c is an integer from 0 to 4, and * represents the bonding part}.

[0174] <32>

[0175] According to the polyimide copolymer of Project 31, wherein X3 in the above general formula (2) is selected from at least one of the following general formula (A-3), a structure derived from 4,4'-oxyphthalic anhydride (ODPA), and a structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0176]

[0177] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}.

[0178] <33>

[0179] A polyimide copolymer, characterized in that it comprises structural units represented by the following general formula (2):

[0180]

[0181] In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, n and m are positive integers, the structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M.

[0182] X4 does not include groups derived from 4,4'-diaminodiphenyl sulfone or 2,2'-bis(trifluoromethyl)benzidine.

[0183] and,

[0184] As described above, X3 comprises at least one structure selected from the group consisting of the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0185]

[0186] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}.

[0187] <34>

[0188] According to the polyimide copolymer described in Project 33, wherein X4 in the above general formula (2) is selected from at least one of the structures shown in the following general formulas (A-4), (A-5), and (A-6).

[0189]

[0190] In the formula, R8~R 11 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4, Z2 represents a linking group, and * represents a bonding part.

[0191]

[0192] In the formula, R 12 and R 13Each of the above-mentioned groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * represents a bonding part, except when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF) and the above-mentioned general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone.

[0193]

[0194] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and ο are each an integer from 0 to 4, and * represents the bonding part.

[0195] <35>

[0196] According to any one of items 31 to 34, the polyimide copolymer, wherein X1 in the above general formula (2) is selected from at least one of the following groups: a structure derived from biphenyl tetracarboxylic acid dianhydride (BPDA), a structure derived from 4,4'-oxophthalic acid dianhydride (ODPA), and a structure derived from 4,4'-biphenyl bis(triphenyl phthalic acid monoester anhydride) (TAHQ).

[0197] <36>

[0198] The polyimide copolymer according to any one of items 31 to 35, wherein the molar ratio (X2 / X1) of X2 included in the above general formula (2) is 0.84 to 1.00, and the molar ratio (X4 / X3) of X4 included in the above general formula (2) is 1.01 to 2.00.

[0199] <37>

[0200] According to any one of items 31 to 36, the polyimide copolymer wherein the molar ratio (number of moles of structural unit N: number of moles of structural unit M) of the polyimide composed of X1 and X2 in the above general formula (2) is in the range of 60:40 to 95:5.

[0201] <38>

[0202] A resin composition characterized by having a polyimide precursor of general formula (I) or having a polyimide precursor backbone of general formula (I) and a polyimide backbone of general formula (II), wherein the resin composition comprises an aprotic polar substance having a boiling point of 250°C to 350°C.

[0203]

[0204] {In the formula, P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer}

[0205]

[0206] {In the formula, P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer}.

[0207] <39>

[0208] A resin composition comprising a polyimide of general formula (II), a solvent, and an aprotic polar substance having a boiling point of 250°C to 350°C.

[0209]

[0210] {In the formula, P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer}.

[0211] The effects of the invention

[0212] According to the present invention, a polyamic acid-imide copolymer and a resin composition comprising the thereof that combine transparency and heat resistance can be provided. Furthermore, a polyimide film with excellent transparency, haze, heat resistance, and coefficient of linear expansion, and a method for manufacturing the same, can also be provided. Alternatively, a block copolymer of polyimide with excellent bending resistance and transparency using an aromatic acid dianhydride having a fluorene backbone as the main component and polyamic acid with excellent heat resistance can be provided. Furthermore, a polyamic acid-imide copolymer resin composition, polyimide, or polyimide film, and a method for manufacturing the same, that combines transparency and heat resistance, and consequently low residual stress and bending resistance, can also be provided. Additionally, a resin composition comprising polyamic acid or a polyamic acid-imide copolymer using 4-amino-3-fluorophenyl-4-aminobenzoate (APAB) that can reduce defects in polyimide films during infrared (IR) curing can also be provided. Furthermore, a defect-reduced polyimide film and a method for manufacturing the same, can also be provided. In addition, according to the present invention, a resin composition capable of obtaining a polyimide resin film with excellent in-plane uniformity of film thickness and low yellowness (YI value) can also be provided, as well as a method for manufacturing a polyimide resin film, a method for manufacturing a display, a method for manufacturing a laminate, and a method for manufacturing a flexible device. Attached Figure Description

[0213] Figure 1 This is a schematic diagram illustrating the structure above the polyimide substrate of a top-emitting flexible organic EL display, which is an example of a display according to one embodiment of the present invention. Detailed Implementation

[0214] The following provides a detailed description of exemplary embodiments of the present invention (hereinafter referred to as "embodiments"). It should be noted that the present invention is not limited to the following embodiments and can be implemented with various modifications within its scope. Furthermore, unless otherwise stated, the characteristic values ​​described in this disclosure refer to values ​​measured by the methods described in the [Examples] section or by methods equivalent to those understood by those skilled in the art.

[0215] <Resin Composition>

[0216] The resin composition provided by one aspect of the present invention comprises: (c) a polyamic acid-imide copolymer, polyimide, or polyamic acid containing (a) polyamic acid and / or (b) polyimide; and (d) an organic solvent, optionally containing (e) an imidization catalyst and other components as desired.

[0217] The following sections will explain each component in turn.

[0218] <First Implementation>

[0219] (A) Polyamic acid-imide copolymer

[0220] The first embodiment of this disclosure provides a polyamic acid-imide copolymer, characterized in that it comprises a structural unit L represented by the following general formula (1).

[0221]

[0222] {In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, n, m, and l are positive integers, and the structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M}

[0223] Furthermore, X2 has the structure shown in the following general formula (A-1) or the following general formula (A-2).

[0224]

[0225] {In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b are each independent integers from 0 to 4, and * represents the bonding part}

[0226]

[0227] {In the formula, R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, c is an integer from 0 to 4, and * represents the bonding part}

[0228] In addition, as a specific example of the structure shown in general formula (A-2), the following general formula (A-2a) can be listed.

[0229]

[0230] {In the formula, R3, c, and * are as defined in general formula (A-2)}

[0231] The polyamic acid-imide copolymer of the first embodiment can be used as a polyimide precursor. When used to form a polyimide film, it exhibits a low coefficient of linear expansion, low residual stress, and low haze and yellowness (YI) values. Furthermore, regarding the polyamic acid-imide copolymer of the first embodiment, when used to form a polyimide film, it exhibits low yellowness (YI) and low haze in high-temperature regions. From this perspective, the weight-average molecular weight of the polyamic acid-imide copolymer of the first embodiment is preferably 170,000 or more, and / or, when X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate, it is preferable that it does not include the following components 1 and 2:

[0232] When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), X2 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and

[0233] The 2.X3 group is derived from norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2”-norcamphene-5,5”,6,6”-tetracarboxylic acid dianhydride.

[0234] <Second Implementation>

[0235] The second embodiment of this disclosure provides a polyamic acid-imide copolymer, characterized in that it comprises structural unit L as shown in the above general formula (1), and as X1 and / or X3, it comprises at least one selected from the group consisting of the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA), the structure derived from biphenyl tetracarboxylic acid dianhydride (BPDA), and the structure derived from 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ).

[0236]

[0237] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}

[0238] The polyamic acid-imide precursor of the second embodiment exhibits low coefficient of linear expansion, low residual stress, excellent bending resistance, and low haze and yellowness (YI) values ​​when used to form polyimide films. Furthermore, the polyamic acid-imide copolymer of the second embodiment exhibits low yellowness (YI) and low haze (YI) values ​​in high-temperature regions when used to form polyimide films. From the viewpoint of the second embodiment, X3 preferably comprises at least one of the following: a structure selected from the group consisting of the structure shown in general formula (A-3), a structure derived from ODPA, and a structure derived from 6FDA. And / or, when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), X4 preferably does not include groups derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine.

[0239] <Third Implementation Method>

[0240] In a third embodiment of this disclosure, the resin composition is characterized by having a polyimide precursor as shown in general formula (I), or having a polyimide precursor backbone as shown in general formula (I) and a polyimide backbone as shown in general formula (II), and containing an aprotic polar substance with a boiling point of 250°C to 350°C; or, the resin composition is characterized by containing a polyimide as shown in general formula (II), a solvent, and an aprotic polar substance with a boiling point of 250°C to 350°C.

[0241] (Polyimide precursor)

[0242]

[0243] In the formula, P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer.

[0244] (Polyimide resin)

[0245]

[0246] In the formula, P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer.

[0247] The polyimide of the third embodiment is obtained by thermally imidizing a polyimide precursor, or it may be chemically imidized. From the viewpoint of the transparency of the resulting polyimide film, thermal imidization is preferred. Furthermore, the resin composition may contain an imidization accelerator.

[0248] The resin composition of the third embodiment contains an aprotic polar substance with a boiling point of 250°C to 350°C. During the curing process (heating process), the aprotic polar substance acts as a plasticizer at a high temperature of, for example, above 250°C, making the resin soft and fluid. When a polyimide resin film (hereinafter also referred to as a polyimide film) is made, the in-plane uniformity of the film thickness is improved, and YI can also be reduced.

[0249] It should be noted that the resin composition of the third embodiment may further include a solvent, such as an aprotic solvent. This aprotic solvent should be different from the aforementioned aprotic polar substances with a boiling point of 250°C to 350°C.

[0250] Here, the P2 group in formulas (I) and (II) is an anhydride residue, which may be the same or different. Additionally, the P1 group in formulas (I) and (II) is a diamine residue, which may be the same or different.

[0251] <Fourth Implementation>

[0252] (B) Polyamic acid

[0253] The fourth embodiment of this disclosure provides a polyamic acid, or a polyamic acid-imide copolymer containing structural units derived therefrom, characterized in that it is a polyamic acid containing structural units represented by the following general formula (3) or a polyamic acid-imide copolymer containing structural units derived therefrom, which is compounded with a specific (e)imidization catalyst or the polyamic acid has a weight-average molecular weight of 170,000 or more. The polyamic acid of the fourth embodiment, or the polyamic acid-imide copolymer containing structural units derived therefrom, can reduce defects in polyimide films during infrared (IR) curing.

[0254]

[0255] In the formula, X1 represents a tetravalent organic group, X2 represents a divalent organic group, and n is a positive integer.

[0256] As X2 in the above general formula (3), it includes the structure shown in the following general formula (A-1).

[0257]

[0258] (In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b are each independent integers from 0 to 4, and * represents the bonding part)}

[0259] The features of the first, second, third, and fourth embodiments can be combined or interchanged. The common configurations and preferred configurations of the first, second, third, and fourth embodiments will be described below.

[0260] (a) <Implementation of the polyamic acid portion>

[0261] The polyamic acid portion constituting the polyamic acid-imide copolymer of the present invention is the portion represented by structural unit N in the above general formula (1).

[0262] In the above general formula (1), X1 is a tetravalent organic group, and the multiple X1s present in the polyimide precursor may be chosen to be the same or different from each other. As X1, a tetravalent organic group derived from the following tetracarboxylic dianhydride can be exemplified.

[0263] Examples of tetracarboxylic dianhydrides include aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms, aliphatic tetracarboxylic dianhydrides with 6 to 50 carbon atoms, and alicyclic tetracarboxylic dianhydrides with 6 to 36 carbon atoms. Among these, aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms are preferred from the viewpoint of yellowness in the high-temperature region. The number of carbon atoms referred to here also includes the number of carbon atoms contained in the carboxyl group.

[0264] Examples of aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms include 4,4'-(hexafluoroisopropyl)diphthalic anhydride (hereinafter also referred to as 6FDA), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic anhydride, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride. Carboxylic acid dianhydride (hereinafter also abbreviated as DSDA), 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, methylene-4,4-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride, 2,2-propylidene-4,4'-diphthalic acid dianhydride, 1,2-ethylidene-4,4'-diphthalic acid dianhydride, 1,3-trimethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene-4,4'-diphthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic acid dianhydride, 4,4'-oxophthalic acid dianhydride (hereinafter also abbreviated as ODPA), p-phenylene 1,3-bis(3,4-dicarboxyphenyl) phthalic anhydride (hereinafter also abbreviated as TAHQ), thio-4,4'-diphthalic anhydride, sulfonyl-4,4'-diphthalic anhydride, 1,3-bis(3,4-dicarboxyphenyl)phthalic anhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phthalic anhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phthalic anhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4 ...methane dianhydr Examples of dianhydrides include: 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracitetetracarboxylic acid dianhydride, and 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride.

[0265] Examples of aliphatic tetracarboxylic dianhydrides with 6 to 50 carbon atoms include ethylene tetracarboxylic dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride.

[0266] Examples of alicyclic tetracarboxylic acid dianhydrides with 6 to 36 carbon atoms include 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, cyclopentanetetracarboxylic acid dianhydride, cyclohexane-1,2,3,4-tetracarboxylic acid dianhydride, cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, cyclopentanone dispironolanetetracarboxylic acid dianhydride (hereinafter also abbreviated as CPODA), 3,3',4,4'-dicyclohexyltetracarboxylic acid dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4'-bis(cyclohexane-12-dicarboxylic acid) dianhydride, 1,2-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, and 2,2-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride. Propyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, REL-[1S,5R,6R]-3-oxabicyclo[3,2]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, ethylene glycol-bis-3,4-dicarboxylic acid anhydride (phenyl) ether, etc.

[0267] In a preferred embodiment, X1 is derived from at least one selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxophthalic anhydride (ODPA), and cyclopentanone bisspironolborneol tetracarboxylic dianhydride (CPODA).

[0268] From the viewpoint of balancing the coefficient of linear expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in the high-temperature region, PMDA, BPDA, DSDA, TAHQ, ODPA, and CPODA are preferred, with BPDA, TAHQ, and ODPA being more preferred.

[0269] For polyamic acid-imide copolymers, dicarboxylic acids can be used as polyimide precursors, for example, without compromising their properties, in addition to the aforementioned tetracarboxylic acid dianhydrides. By using such precursors, the mechanical elongation, glass transition temperature, and yellowness of the resulting film can be improved, and various properties can be adjusted. Examples of such dicarboxylic acids include aromatic dicarboxylic acids and alicyclic dicarboxylic acids. At least one compound selected from the group consisting of aromatic dicarboxylic acids with 8 to 36 carbon atoms and alicyclic dicarboxylic acids with 6 to 34 carbon atoms is particularly preferred. The number of carbon atoms referred to here also includes the number of carbon atoms contained in the carboxyl group. Among these, dicarboxylic acids with aromatic rings are preferred.

[0270] As dicarboxylic acids, specific examples include isophthalic acid, terephthalic acid, 4,4'-biphenyl dicarboxylic acid, 3,4'-biphenyl dicarboxylic acid, 3,3'-biphenyl dicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3,4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid, 4,4'-oxobisbenzoic acid, 3,4'-oxobisbenzoic acid, 3,3'-oxobisbenzoic acid, 2,2-bis(4-carboxyphenyl)propane, 2,2-bis(3- Carboxyphenyl)propane, 2,2'-dimethyl-4,4'-biphenyl dicarboxylic acid, 3,3'-dimethyl-4,4'-biphenyl dicarboxylic acid, 2,2'-dimethyl-3,3'-biphenyl dicarboxylic acid, 9,9-bis(4-(4-carboxyphenoxy)phenyl)fluorene, 9,9-bis(4-(3-carboxyphenoxy)phenyl)fluorene, 4,4'-bis(4-carboxyphenoxy)biphenyl, 4,4'-bis(3-carboxyphenoxy)biphenyl, 3,4'-bis(4-)biphenyl, 3,3'-bis(4-)biphenyl (Carboxyphenoxy)biphenyl, 3,3'-bis(3-carboxyphenoxy)biphenyl, 4,4'-bis(4-carboxyphenoxy)-p-terphenyl, 4,4'-bis(4-carboxyphenoxy)-m-terphenyl, 3,4'-bis(4-carboxyphenoxy)-p-terphenyl, 3,3'-bis(4-carboxyphenoxy)-p-terphenyl, 3,4'-bis(4-carboxyphenoxy)-m-terphenyl, 4,4'-bis(3-carboxyphenoxy)-p-terphenyl, 4,4'-bis(3-carboxyphenoxy)-m-terphenyl Benzene, 3,4'-bis(3-carboxyphenoxy)-p-terphenyl, 3,3'-bis(3-carboxyphenoxy)-p-terphenyl, 3,4'-bis(3-carboxyphenoxy)-m-terphenyl, 3,3'-bis(3-carboxyphenoxy)-m-terphenyl, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 1,3-phenylene diacetic acid, 1,4-phenylene diacetic acid, etc.; and 5-aminoisophthalic acid derivatives as described in International Publication No. 2005 / 068535, etc. When these dicarboxylic acids are actually copolymerized in polymers, they can be used in the form of acyl chlorides derived from thionyl chloride, active esters, etc.

[0271] In the above general formula (1), X2 is a divalent organic group. Preferably, it is a structure shown in general formula (A-1), general formula (A-4), general formula (A-5), general formula (A-6), or a structure derived from a diamine shown in general formula (B-1), or a structure derived from BAFL, BFAF, BAOFL, 44DAS, 33DAS, 44ODA, 34ODA, etc. As X2, from the viewpoint of yellowness (YI value) in the high-temperature region, a structure derived from 4-aminophenyl-4-aminobenzoic acid ester is preferred. From the viewpoint of haze (HAZE value), at least one structure derived from 4-amino-3-fluorophenyl-4-aminobenzoic acid ester (APAB), p-phenylenediamine (pPD), BAFL, and BFAF is preferred.

[0272] In one approach, the structure of X2 in general formula (1) is as shown in the following general formula (A-1).

[0273]

[0274] {In the formula, R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b are each independent integers from 0 to 4, and * represents the bonding part}

[0275] Here, R1 and R2 are not limited to being a monovalent organic group having 1 to 20 carbon atoms, hydrogen (in the case where a and / or b = 0), or a halogen. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, and alkoxy groups such as methoxy and ethoxy. When a and / or b = 0, it can be hydrogen, or fluorine can be an example of a halogen. From the viewpoint of yellowness (YI value) in the high-temperature region, hydrogen and / or phenyl are preferred, and from the viewpoint of haze (Haze value), at least one of the groups consisting of hydrogen, methyl, and fluorine is preferred.

[0276] Here, a and b are not limited to integers from 0 to 4. However, from the viewpoint of yellowness (YI value) and residual stress, integers from 0 to 2 are preferred, and from the viewpoint of yellowness (YI value) in the high-temperature region, 0 is particularly preferred.

[0277] In one approach, the structure of X2 in general formula (1) is as shown in the following general formula (A-6).

[0278]

[0279] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and o are each an integer from 0 to 4, and * represents the bonding part.

[0280] Here, R 14 and R 15 There are no limitations on whether the organic group is a monovalent organic group having 1 to 20 carbon atoms, hydrogen (in the case where n and o = 0), or a halogen. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, alkoxy groups such as methoxy and ethoxy, etc. When n and o = 0, it can be hydrogen, or fluorine can be an example of a halogen. From the viewpoint of yellowness (YI value) in the high-temperature region, hydrogen and / or phenyl are preferred, and from the viewpoint of haze (Haze value), at least one of the following groups is preferred: hydrogen, methyl, and fluorine.

[0281] Here, n and o are not limited to integers from 0 to 4. From the viewpoint of yellowness (YI value) and residual stress, integers from 0 to 2 are preferred, and from the viewpoint of yellowness (YI value) in the high-temperature region, 0 is particularly preferred.

[0282] In one approach, the structure of X2 in general formula (1) is as shown in the following general formula (A-2).

[0283]

[0284] {In the formula, R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, c is an integer from 0 to 4, and * represents the bonding part}

[0285] Here, R3 is not limited to any single organic group having 1 to 20 carbon atoms, hydrogen (in the case of c=0), or halogen. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, and alkoxy groups such as methoxy and ethoxy. When c=0, it can be hydrogen, or fluorine can be an example of a halogen. From the viewpoint of yellowness (YI value) in the high-temperature region, hydrogen is preferred, and from the viewpoint of haze (Haze value), methyl and / or fluorine are preferred.

[0286] Here, c is not limited to any integer from 0 to 4. However, from the viewpoint of yellowness (YI value) and residual stress, an integer from 0 to 2 is preferred, and from the viewpoint of yellowness (YI value) in the high-temperature region, 0 is particularly preferred.

[0287] In one approach, the structural unit represented by general formula (A-1) is derived from the diamine represented by general formula (B-1) below.

[0288]

[0289] {In the formula, R1, R2, a, and b are defined in the same way as in general formula (A-1)}

[0290] As a diamine represented by general formula (B-1), more specifically, examples include 4-aminophenyl-4-aminobenzoate (hereinafter also referred to as APAB), 2-methyl-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 2Me-APAB), 3-methyl-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 3Me-APAB), 2-fluoro-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 2F-APAB), 3-fluoro-4-aminophenyl-4-aminobenzoate (hereinafter also referred to as 3F-APAB), and 3-methyl-4-aminophenyl-3-methyl-4-aminobenzoate (hereinafter also referred to as 3,3Me-APAB). From the viewpoint of yellowness (YI value) in the high-temperature region, APAB is preferred, and from the viewpoint of reducing haze (Haze value), APAB, 3Me-APAB, and 3F-APAB are preferred.

[0291] In one approach, the structural unit represented by general formula (A-2) is derived from the diamine represented by general formula (B-2) below.

[0292]

[0293] {In the formula, R3 and c are defined in the same way as in general formula (A-2)}

[0294] As a diamine represented by the general formula (B-2), more specifically, examples include p-phenylenediamine (pPD), m-phenylenediamine, 3,5-diaminobenzoic acid, etc. From the viewpoint of heat resistance at high temperatures, pPD is preferred.

[0295] Polyamic acid, polyimide, polyamic acid-imide copolymer and polyimide copolymer can use other diamines based on the diamines shown in the above general formulas (B-1) and (B-2) without impairing yellowness, haze, residual stress, etc., or can use other diamines instead of the diamines shown in general formulas (B-1) and (B-2).

[0296] Other diamines include, for example, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 4 The diamines used are preferably selected from one or more of the following: 4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl)hexafluoropropane, and 1,4-bis(3-aminopropyldimethylsilyl)benzene. The content of the other diamines in all diamines is preferably 20 mol% or less, and particularly preferably 10 mol% or less. On the other hand, from the viewpoint of heat resistance at high temperatures, it is preferable that the diamine used does not contain organosilicon-based diamines. Examples include "X-22-9409" and "X-22-1660B-3" manufactured by Shin-Etsu Chemical Industry Co., Ltd., which are commercially available organosilicon-based diamines.

[0297] In the polyamic acid portion of the above general formula (1), the molar ratio (X2 / X1) of X2 to X1 is preferably 0.84 to 1.00 or 0.85 to 1.2, more preferably 0.90 to 1.1, and even more preferably 0.92 to 1.00. When X1 / X2 is 0.84 or more or 0.85 or more, the residual stress is low and YI is reduced. When X1 / X2 is 1.2 or less or 1.00 or less, the mechanical properties such as elongation and breaking strength are excellent.

[0298] The weight-average molecular weight (Mw) of the polyamic acid and the polyamic acid portion is preferably 1,000 or more, more preferably 1,000 to 300,000 or 2,639 to 300,000, even more preferably 10,000 to 200,000 or 10,000 to 250,000, and particularly preferably 30,000 to 200,000. When the weight-average molecular weight is 1,000 or more, the mechanical properties such as elongation and tensile strength are excellent, the residual stress is low, and the YI is reduced. When the weight-average molecular weight is 300,000 or less, the weight-average molecular weight is easy to control during the synthesis of polyamic acid, and a resin composition with suitable viscosity can be obtained, resulting in good coatability of the resin composition. Furthermore, when the Mw of the polyamic acid and the polyamic acid portion is 170,000 or more, there is a tendency for excellent transparency, haze, heat resistance, and coefficient of linear expansion. Therefore, an Mw of 220,000 or more is preferred, and even more preferred. This tendency is more pronounced when X2 in general formula (1) has the structure shown in the above general formula (A-1). In this disclosure, the weight-average molecular weight is a value obtained using gel permeation chromatography (hereinafter also referred to as GPC) in the form of a standard polystyrene conversion value.

[0299] (b) <Implementation of the polyimide portion>

[0300] The polyimide portion constituting the polyamic acid-imide copolymer of the present invention is the portion shown by structural unit M in the above general formula (1).

[0301] In the above general formula (1), X3 is a tetravalent organic group, preferably a structure shown in the following general formula (A-3) or a structure derived from at least one of 4,4'-oxophthalic dianhydride (ODPA) and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). A tetravalent organic group derived from the tetracarboxylic acid dianhydride described in the above <Examples of Polyamic Acid Section> can be used. In addition, the plurality of X3 present in the polyamic acid-imide copolymer that can be used as a polyimide precursor may be identical or different from each other, and may be identical or different from each other with X1.

[0302] As for X3, from the viewpoint of yellowness (YI value) in the high-temperature region, a structure derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF) is preferred, and from the viewpoint of residual stress, a structure derived from ODPA is preferred.

[0303] Examples of tetracarboxylic dianhydrides that can be used in conjunction with or replace BPAF, ODPA, and 6FDA include aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms, aliphatic tetracarboxylic dianhydrides with 6 to 50 carbon atoms, and alicyclic tetracarboxylic dianhydrides with 6 to 36 carbon atoms. From the viewpoint of yellowness in the high-temperature region, aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms are preferred. The carbon number referred to here also includes the number of carbons contained in the carboxyl group.

[0304] Examples of aromatic tetracarboxylic dianhydrides with 8 to 36 carbon atoms include 4,4'-(hexafluoroisopropyl)diphthalic anhydride (hereinafter also referred to as 6FDA), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic anhydride, pyromellitic dianhydride (hereinafter also referred to as PMDA), 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA), and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride. Carboxylic acid dianhydride (hereinafter also abbreviated as DSDA), 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, methylene-4,4-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride, 2,2-propylidene-4,4'-diphthalic acid dianhydride, 1,2-ethylidene-4,4'-diphthalic acid dianhydride, 1,3-trimethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene-4,4'-diphthalic acid dianhydride, 1,5-pentamethylene-4,4'-diphthalic acid dianhydride, 4,4'-oxophthalic acid dianhydride (hereinafter also abbreviated as ODPA), p-phenylene 1,3-bis(3,4-dicarboxyphenyl) phthalic anhydride (hereinafter also abbreviated as TAHQ), thio-4,4'-diphthalic anhydride, sulfonyl-4,4'-diphthalic anhydride, 1,3-bis(3,4-dicarboxyphenyl)phthalic anhydride, 1,3-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,4-bis(3,4-dicarboxyphenoxy)phthalic anhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phthalic anhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phthalic anhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4 ...methane dianhydr Examples of dianhydrides include: 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracitetetracarboxylic acid dianhydride, and 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride.

[0305] Examples of aliphatic tetracarboxylic dianhydrides with 6 to 50 carbon atoms include ethylene tetracarboxylic dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride.

[0306] Examples of alicyclic tetracarboxylic acid dianhydrides with 6 to 36 carbon atoms include 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, cyclopentanetetracarboxylic acid dianhydride, cyclohexane-1,2,3,4-tetracarboxylic acid dianhydride, cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, cyclopentanone dispironolanetetracarboxylic acid dianhydride (hereinafter also abbreviated as CPODA), 3,3',4,4'-dicyclohexyltetracarboxylic acid dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4'-bis(cyclohexane-12-dicarboxylic acid) dianhydride, 1,2-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, and 2,2-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride. Propyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, REL-[1S,5R,6R]-3-oxabicyclo[3,2]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid anhydride, ethylene glycol-bis-3,4-dicarboxylic acid anhydride (phenyl) ether, etc.

[0307] In a preferred embodiment, X1 or X3 is derived from at least one selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxophthalic anhydride (ODPA), and cyclopentanone bisspironolborneol tetracarboxylic dianhydride (CPODA).

[0308] From the viewpoint of balancing the coefficient of linear expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in the high-temperature region, PMDA, BPDA, DSDA, TAHQ, and CPODA are preferred, with BPDA and TAHQ being more preferred.

[0309] For polyamic acid-imide copolymers, for example, as a polyimide precursor, a dicarboxylic acid can be used in addition to the aforementioned tetracarboxylic acid dianhydride without compromising its properties. By using such a precursor, the mechanical elongation of the obtained film is improved, the glass transition temperature is increased, and the yellowness is reduced, thus adjusting various properties. Examples of such dicarboxylic acids include aromatic dicarboxylic acids and alicyclic dicarboxylic acids. At least one compound selected from the group consisting of aromatic dicarboxylic acids with 8 to 36 carbon atoms and alicyclic dicarboxylic acids with 6 to 34 carbon atoms is particularly preferred. The number of carbon atoms referred to here also includes the number of carbon atoms contained in the carboxyl group. Among these, dicarboxylic acids with aromatic rings are preferred.

[0310] As dicarboxylic acids, specific examples include isophthalic acid, terephthalic acid, 4,4'-biphenyl dicarboxylic acid, 3,4'-biphenyl dicarboxylic acid, 3,3'-biphenyl dicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-sulfonylbisbenzoic acid, 3,4'-sulfonylbisbenzoic acid, 3,3'-sulfonylbisbenzoic acid, 4,4'-oxobisbenzoic acid, 3,4'-oxobisbenzoic acid, 3,3'-oxobisbenzoic acid, 2,2-bis(4-carboxyphenyl)propane, 2,2-bis(3- Carboxyphenyl)propane, 2,2'-dimethyl-4,4'-biphenyl dicarboxylic acid, 3,3'-dimethyl-4,4'-biphenyl dicarboxylic acid, 2,2'-dimethyl-3,3'-biphenyl dicarboxylic acid, 9,9-bis(4-(4-carboxyphenoxy)phenyl)fluorene, 9,9-bis(4-(3-carboxyphenoxy)phenyl)fluorene, 4,4'-bis(4-carboxyphenoxy)biphenyl, 4,4'-bis(3-carboxyphenoxy)biphenyl, 3,4'-bis(4-)biphenyl, 3,3'-bis(4-)biphenyl (Carboxyphenoxy)biphenyl, 3,3'-bis(3-carboxyphenoxy)biphenyl, 4,4'-bis(4-carboxyphenoxy)-p-terphenyl, 4,4'-bis(4-carboxyphenoxy)-m-terphenyl, 3,4'-bis(4-carboxyphenoxy)-p-terphenyl, 3,3'-bis(4-carboxyphenoxy)-p-terphenyl, 3,4'-bis(4-carboxyphenoxy)-m-terphenyl, 4,4'-bis(3-carboxyphenoxy)-p-terphenyl, 4,4'-bis(3-carboxyphenoxy)-m-terphenyl Benzene, 3,4'-bis(3-carboxyphenoxy)-p-terphenyl, 3,3'-bis(3-carboxyphenoxy)-p-terphenyl, 3,4'-bis(3-carboxyphenoxy)-m-terphenyl, 3,3'-bis(3-carboxyphenoxy)-m-terphenyl, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 1,3-phenylene diacetic acid, 1,4-phenylene diacetic acid, etc.; and 5-aminoisophthalic acid derivatives as described in International Publication No. 2005 / 068535, etc. When these dicarboxylic acids are actually copolymerized in polymers, they can be used in the form of acyl chlorides derived from thionyl chloride, active esters, etc.

[0311] In one manner, the structure of X3 in general formula (1) or general formula (2) described below is as shown in general formula (A-3) or derived from 4,4'-oxophthalic anhydride (ODPA) and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0312]

[0313] {In the formula, R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part}

[0314] Here, R6 to R9 are not limited to being a monovalent organic group with 1 to 20 carbon atoms, hydrogen (in the case of d to g = 0), or a halogen. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, and alkoxy groups such as methoxy and ethoxy. When d to g = 0, it can be hydrogen, or fluorine can be a halogen. From the viewpoint of yellowness (YI value) in the high-temperature region, hydrogen is preferred, and from the viewpoint of haze (Haze value), fluorine is preferred.

[0315] Here, Z1 can be exemplified by single bonds, methylene, ethylene, ethers, ketones, etc. Among these, from the viewpoint of YI in the high-temperature region, single bonds are more preferred, and from the viewpoint of residual stress, single bonds and ethers are preferred.

[0316] Here, d to g are not limited to integers from 0 to 4. However, from the viewpoint of yellowness (YI value) and residual stress, integers from 0 to 2 are preferred, and from the viewpoint of yellowness (YI value) in the high-temperature region, 0 is particularly preferred.

[0317] In one approach, the structural unit represented by general formula (A-3) is derived from the acid dianhydride represented by general formula (B-3) below.

[0318]

[0319] {In the formula, R4~R7, d~g and Z1 are defined in the same way as in general formula (A-3), d and e are each preferably integers from 0 to 3, and f and g are each preferably integers from 0 to 4.}

[0320] As an acid dianhydride represented by general formula (B-3), more specifically, examples include 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA). From the viewpoint of reducing haze and high-temperature regions, BPAF is preferred, and from the viewpoint of residual stress, BPAF and BPF-PA are preferred.

[0321] In general formula (1) or general formula (2) described below, X4 is a divalent organic group, preferably a structure shown in at least one of the following general formulas (A-4) to (A-6), and a divalent organic group derived from the diamine described in the above <Examples of Polyamic Acid Section> can be used. In addition, the plurality of X4 present in the polyimide or the polyimide section may be chosen to be the same or different from each other. From the viewpoint of taking into account both opposite properties when making polyimide, it is preferable that they are different from X2, and more preferably the diamine component constituting X2 and the diamine component constituting X4 are different in either diamine composition or diamine type.

[0322] In one approach, the structure of X4 in general formula (1) or general formula (2) described later is as shown in general formula (A-4) below.

[0323]

[0324] In the formula, R8~R 11 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms; h to k are each independently an integer from 0 to 4; Z2 represents a linking group; and * represents a bonding part.

[0325] Here, R8~R 11 There are no limitations on whether the organic group is a monovalent organic group with 1 to 20 carbon atoms, hydrogen (in the case of h to k = 0), or a halogen. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, and alkoxy groups such as methoxy and ethoxy. When h to k = 0, it can be hydrogen, or fluorine can be used as a halogen. Among these, hydrogen is preferred from the viewpoint of yellowness (YI value) in the high-temperature region, and fluorine is preferred from the viewpoint of haze (Haze value).

[0326] Here, h to k are not limited to integers from 0 to 4. However, from the viewpoint of yellowness (YI value) and residual stress, integers from 0 to 2 are preferred, and from the viewpoint of yellowness (YI value) in the high-temperature region, 0 is particularly preferred.

[0327] Examples of Z2 include single bonds, methylene, ethylene, ethers, and ketones. Among these, single bonds are preferred from the perspective of YI in the high-temperature region.

[0328] In one approach, the structure of X4 in general formula (1) or general formula (2) described later is as shown in general formula (A-5) below.

[0329]

[0330] In the formula, R 12 and R 13Each of the above general formulas (A-5) independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, l and m are each an integer from 0 to 4, and * represents a bonding part. In general formula (A-5), when X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate and X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), general formula (A-5) does not include 4,4'-diaminodiphenyl sulfone or a group derived therefrom.

[0331] Here, R 12 R 13 There are no limitations if each of the organic groups is a monovalent organic group having 1 to 20 carbon atoms or a halogen such as fluorine. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl, halogen-containing groups such as trifluoromethyl, aryl groups such as phenyl and naphthyl, and alkoxy groups such as methoxy and ethoxy. Among these, methyl is preferred from the viewpoint of YI in the high-temperature region.

[0332] Here, l and m are not limited to integers from 0 to 4. However, from the viewpoint of YI and residual stress, integers from 0 to 2 are preferred, and from the viewpoint of YI in the high-temperature region, 0 is particularly preferred.

[0333] In one approach, the structure of X4 in general formula (1) or general formula (2) described later is as shown in general formula (A-6) below.

[0334]

[0335] In the formula, R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and o are each an integer from 0 to 4, and * represents the bonding part.

[0336] Here, R 14 and R 15 There is no limitation if each organic group is a monovalent organic group having 1 to 20 carbon atoms. Examples of such organic groups include alkyl groups such as methyl, ethyl, and propyl; halogen-containing groups such as trifluoromethyl; aryl groups such as phenyl and naphthyl; alkoxy groups such as methoxy and ethoxy; etc. Among these, methyl and phenyl are preferred from the viewpoint of YI in the high-temperature region. Here, n and 0 are not limited if they are integers from 0 to 4. Among these, integers from 0 to 2 are preferred from the viewpoint of YI and residual stress, and 0 is particularly preferred from the viewpoint of YI in the high-temperature region.

[0337] In one approach, the structural unit represented by general formula (A-4) is derived from the diamine represented by general formula (B-4) below.

[0338]

[0339] In the formula, R8~R 11 And h~k are defined in the same way as in general formula (A-4)}

[0340] As a diamine represented by general formula (B-4), more specifically, examples include 9,9-bis(4-aminophenyl)fluorene (BAFL), 9,9-bis(3-fluoro-4-aminophenyl)fluorene (BFAF), and 9,9-bis(4-(aminophenoxy)phenyl)fluorene (BAOFL). From the viewpoint of yellowness (YI value) at high temperature, BFAF is preferred, and from the viewpoint of reducing haze (Haze value), BAFL is preferred.

[0341] In another embodiment, the structural unit represented by general formula (A-5) is derived from diamines represented by general formula (B-5-1) or general formula (B-5-2) below.

[0342]

[0343] In the formula, R 12 and R 13 l and m are defined in the same way as in general formula (A-5).

[0344] As diamines represented by general formulas (B-5-1) and (B-5-2), more specifically, examples include 4,4'-diaminodiphenyl sulfone (44DAS) and 3,3'-diaminodiphenyl sulfone (33DAS). Other diamines, more specifically, include bis[4-(4-aminophenoxy)phenyl]sulfone and bis[4-(3-aminophenoxy)phenyl]sulfone. From the viewpoint of yellowness (YI value) at high temperatures, 44DAS is preferred, and from the viewpoint of reducing residual stress, 33DAS is preferred.

[0345] In one approach, the structural unit represented by general formula (A-6) is derived from diamines, etc., represented by general formula (B-6) below.

[0346]

[0347] In the formula, R 14 and R 15 , n and ο are defined in the same way as in general formula (A-6)}

[0348] More specifically, examples of diamines represented by the general formula (B-6) include 4,4'-diaminodiphenyl ether (44ODA), 3,4'-diaminodiphenyl ether (34ODA), and 2,3'-diaminodiphenyl ether. From the viewpoint of yellowness (YI value) at high temperatures, 44ODA is preferred, and from the viewpoint of reducing residual stress, 34ODA is preferred.

[0349] The weight-average molecular weight (Mw) of the polyimide or the polyimide portion is preferably 1,000 to 100,000, more preferably 2,000 to 80,000 or 2,639 to 80,000, and particularly preferably 5,000 to 60,000. When the weight-average molecular weight is 1,000 or higher, mechanical properties such as elongation and tensile strength are excellent, residual stress is low, and YI is reduced. When the weight-average molecular weight is 100,000 or lower, phase separation is suppressed when forming polyamic acid-imide copolymer films, and haze value is reduced. In this disclosure, the weight-average molecular weight is a value obtained using gel permeation chromatography (hereinafter also referred to as GPC) in the form of a standard polystyrene conversion value.

[0350] Regarding polyimide or its structural units, the molar ratio (X4 / X3) of X4 to X3 in the above general formula (1) is preferably 0.85 to 2.0 or 1.01 to 2.00, more preferably 0.95 to 1.5, and even more preferably 1.01 to 1.25. When the molar ratio is 0.85 or higher or 1.01 or higher, the heat resistance in the high-temperature region is excellent, and the YI value is reduced. When the molar ratio is 2.00 or lower, the reactivity with the polyamic acid portion is increased, the strength when the film is formed is increased, and therefore the mechanical properties such as elongation and tensile strength are excellent.

[0351] The content of polyimide or polyimide fraction molecules with a molecular weight of less than 1,000 relative to the total amount of polyimide precursor or polyamic acid-imide copolymer is preferably less than 5% by mass, more preferably less than 1% by mass, and even more preferably less than 0.1% by mass. Polyimide films formed from resin compositions using such polyimide or polyimide fractions exhibit low residual stress and reduced haze. The content of molecules with a molecular weight of less than 1,000 relative to the total amount of polyimide or polyimide fraction can be calculated from the peak area obtained by GPC determination using a solution in which the polyimide is dissolved.

[0352] In one embodiment of this disclosure, the polyimide precursor may use other diamines or substitute for the diamines shown in general formulas (B-1) to (B-2) and (B-4) to (B-6) without impairing elongation, strength, stress, yellowness, etc. Other diamines include, for example, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 4 The following are preferred: 4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl)hexafluoropropane, 1,4-bis(3-aminopropyldimethylsilyl)benzene, etc.

[0353] The content of the other diamines mentioned above in all diamines is preferably 20 mol% or less, particularly preferably 10 mol% or less. From the viewpoint of heat resistance at high temperatures, X4 and the diamine constituting it are also preferably free of organosilicon diamines, and more preferably of aromatic diamines, just like X2.

[0354] (c) <Implementation of polyamic acid-imide copolymer>

[0355] The polyamic acid-imide copolymer of the present invention comprises a structural unit L, which is shown in the above general formula (1) and contains a structural unit M as a polyamic acid portion and a structural unit N as a polyimide portion. Specific embodiments thereof are shown below.

[0356] The diamine (X2) in the polyamic acid portion and the diamine (X4) in the polyimide portion can have the same composition or diamine type, or they can have different compositions or diamine types. "Same composition" means that when the polyamic acid portion uses one or more diamines, the diamine in the polyimide portion has the same composition. Conversely, "different composition" means that when the polyamic acid portion uses one or more diamines, the diamine in the polyimide portion does not have the same composition, but is composed of different diamines, or even if the same diamine is used, the ratio is different.

[0357] As one aspect of the present invention, the role of the polyamic acid portion is to provide high thermal stability and excellent dimensional stability in high-temperature regions, preferably with a skeleton that has high molecular planarity and high heat resistance at high temperatures when the polyimide is formed.

[0358] As shown in (a) <Embodiments of the polyamic acid portion>, the dianhydride (X1) is derived from at least one selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyl tetracarboxylic dianhydride (BPDA), 4,4'-biphenyl bis(triphenyl ester anhydride) (TAHQ), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxophthalic anhydride (ODPA), and cyclopentanone bisspironolane tetracarboxylic dianhydride (CPODA).

[0359] From the viewpoint of balancing the coefficient of linear expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in the high-temperature region, PMDA, BPDA, DSDA, TAHQ, ODPA, and CPODA are preferred, with BPDA, TAHQ, and ODPA being more preferred. As X1, in addition to the acid dianhydrides mentioned above, it can also be obtained by using a dicarboxylic acid based on the aforementioned tetracarboxylic dianhydrides without impairing its performance. Furthermore, other tetracarboxylic dianhydrides can be added, but those derived from the skeleton of aromatic tetracarboxylic dianhydrides or aromatic dicarboxylic acids are preferred. Additionally, the ratio of other acid dianhydrides to dicarboxylic acids in X1 is preferably 20 mol% or less, more preferably 10 mol% or less.

[0360] The diamine (X2) of the polyamic acid portion is preferably selected from at least one of the group consisting of (4-aminophenyl-4-aminobenzoate (APAB), 2-methyl-4-aminophenyl-4-aminobenzoate, 3-methyl-4-aminophenyl-4-aminobenzoate, 2-fluoro-4-aminophenyl-4-aminobenzoate (2F-APAB), 3-fluoro-4-aminophenyl-4-aminobenzoate (3F-APAB), 3-methyl-4-aminophenyl-3-methyl-4-aminobenzoate and (2-phenyl-4-aminophenyl)-4-aminobenzoate (ph-APAB), with a coefficient of linear expansion (C From the perspective of balancing TE (transition temperature), chemical resistance, glass transition temperature (Tg), and yellowness in the high-temperature region, APAB, 2F-APAB, 3F-APAB, and Ph-APAB are preferred, with APAB being more preferred. As X2, in addition to the acid dianhydrides described above, other diamines may be added within a range that does not impair its performance, but it is preferable to be an aromatic diamine that does not contain a cyclohexane or cyclopentane ring. The ratio of other diamines in X2 is preferably 20 mol% or less, more preferably 10 mol% or less. That is, the diamine (X4) as the imide moiety described above preferably does not contain the structure shown above, but this is not a limitation if the composition is not exactly the same.

[0361] As one aspect of the present invention, the role of the imide portion is to provide high thermal stability, excellent optical properties, and high solubility in solvents in high-temperature regions. Preferably, it is a framework with excellent optical properties and high solubility in solvents, or a framework that can impart bending resistance when forming a thin film.

[0362] As the dianhydride (X3) of the polyimide portion, as shown in (b) <Embodiments of the Polyimide Portion>, a tetravalent organic group derived from a tetracarboxylic acid dianhydride can be used. Furthermore, the plurality of X3s present in the polyimide precursor or the polyamic acid-imide copolymer may be identical or different from each other, and may be identical or different from each other with X1. As X3, from the viewpoint of excellent yellowness (YI value) and haze (Haze value) in the high-temperature region, a structure derived from BPAF is preferred; from the viewpoint of residual stress, a structure derived from ODPA is preferred. When using a BPAF-derived skeleton, a skeleton selected from PMDA, BPDA, DSDA, TAHQ, ODPA, and CPODA can be used simultaneously to improve thermal stability in the high-temperature region. Among these, a skeleton selected from BPDA, TAHQ, and ODPA is more preferred. The BPAF ratio in X3 is preferably 40 mol% or more, more preferably 50 mol% or more, further preferably 70 mol% or more, and can be 100 mol%. From the viewpoint of excellent flexural strength when producing polyimide films, a higher BPAF ratio is more preferred.

[0363] As the diamine of the aforementioned imide portion, as shown in (b) <Embodiments of the Polyimide Portion>, a divalent organic group derived from the diamine can be used. Furthermore, the plurality of X4s present in the polyimide precursor or the polyamic acid-imide copolymer may be optionally the same or different from each other, and may be optionally the same or different from each other as X2s, but not all of them may be the same. As X4, it is preferably at least one selected from the group consisting of 44BAFL, 33BAFL, BFAF, BAOFL, BAHF, 33DAS, and 44DAS. From the viewpoint of balancing the coefficient of linear expansion (CTE), chemical resistance, glass transition temperature (Tg), and yellowness in the high-temperature region, 44BAFL, 33BAFL, BFAF, BAOFL, 33DAS, 44DAS, 44ODA, and 34ODA are more preferred.

[0364] The polyamic acid-imide copolymer comprises a polyamic acid portion consisting of X1 and X2 and a polyimide portion consisting of X3 and X4. The upper limit of the molar ratio (number of moles of structural unit N: number of moles of structural unit M) between the structural units of the polyamic acid and the polyimide is 95:5, 90:10, 85:15, or 80:20. From the viewpoint of residual stress and haze value, 95:5 is preferred, and from the viewpoint of yellowness (YI value), 80:20 is more preferred. The lower limit of the molar ratio (number of moles of structural unit N: number of moles of structural unit M) between the structural units of the polyamic acid and the polyimide is 30:70, 40:60, 50:50, or 60:40. From the viewpoint of balancing residual stress and yellowness (YI value), 40:60 or 60:40 is preferred.

[0365] The weight-average molecular weight (Mw) of the polyamic acid-imide copolymer (structural unit L) is preferably 2,639 or higher, more preferably 2,639 to 300,000 or 10,000 to 300,000, even more preferably 20,000 to 250,000, and particularly preferably 40,000 to 200,000. When the weight-average molecular weight is 2,639 or higher, the mechanical properties such as elongation and tensile strength are excellent, the residual stress is low, and the YI is reduced. When the weight-average molecular weight is 300,000 or lower, the viscosity and concentration of the polyamic acid-imide copolymer varnish are well balanced, the processability is good, and the film unevenness during coating is reduced. Furthermore, when the weight-average molecular weight (Mw) of the polyamic acid-imide copolymer is 170,000 or more, it tends to have excellent transparency, haze, heat resistance, and coefficient of linear expansion. Therefore, a Mw of 220,000 or more is preferred, and this tendency is more pronounced when the structure shown in the above general formula (A-1) is X2 in general formula (1). Moreover, from the viewpoint of evaluating IR (infrared) curing defects and degassing, the weight-average molecular weight (Mw) of the polyamic acid-imide copolymer is preferably 170,000 or more, and more preferably 220,000 or more.

[0366] In this disclosure, the weight-average molecular weight is a value obtained using gel permeation chromatography (hereinafter also referred to as GPC) in the form of a standard polystyrene equivalent.

[0367] <(B) Implementation methods of polyamic acid>

[0368] Regarding the fourth embodiment of the polyamic acid containing the structural unit shown in general formula (3) and having the structure shown in general formula (A-1) as X2, in general formula (3), X1 is a tetravalent organic group, and the plurality of X1 present in the polyimide precursor may be identical or different from each other. As X1, a tetravalent organic group derived from tetracarboxylic dianhydride may be exemplified, which is the same as the tetracarboxylic dianhydride exemplified with respect to the polyamic acid-imide copolymer in (A) above.

[0369] In one embodiment of polyamic acid, in the above general formula (3), X2 is a divalent organic group, and the plurality of X2 present in the polyimide precursor may be optionally the same or different from each other. As X2, a divalent organic group derived from a diamine may be exemplified, which is the same as the diamine exemplified with respect to the above (A) polyamic acid-imide copolymer.

[0370] Regarding polyamic acid, the structural unit shown in general formula (A-1) is the same as that exemplified with respect to the above-mentioned polyamic acid-imide copolymer (A-1).

[0371] In the fourth embodiment, the weight-average molecular weight (Mw) of the polyamic acid is preferably 3,000 or more, more preferably 10,000 to 300,000, even more preferably 20,000 to 250,000, and particularly preferably 40,000 to 200,000. When the weight-average molecular weight is 3,000 or more, the mechanical properties such as elongation and tensile strength are excellent, the residual stress is low, and the YI is reduced. When the weight-average molecular weight is 300,000 or less, the viscosity and concentration of the polyamic acid-imide copolymer varnish are well balanced, the processability is good, and the film unevenness during coating is reduced.

[0372] Furthermore, from the viewpoints of evaluating IR (infrared) curing defects and degassing, the weight-average molecular weight (Mw) of the polyamic acid in the fourth embodiment is preferably 170,000 or more, and more preferably 240,000 or more. In this disclosure, the weight-average molecular weight is a value obtained using gel permeation chromatography (hereinafter also referred to as GPC) in the form of a standard polystyrene conversion value.

[0373] (Diamine)

[0374] Examples of diamines containing a P1 group in general formulas (I) and (II) include 4,4'-diaminodiphenyl sulfone (4,4'-DAS), 3,4'-diaminodiphenyl sulfone (3,4'-DAS), 3,3'-diaminodiphenyl sulfone (3,3'-DAS), p-phenylenediamine (PDA), m-phenylenediamine, 3,5-diaminobenzoic acid (DABA), 2,2'-dimethylbenzidine (mTB), 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminobenzoyl Tanilide (DABAN), 9,9-bis(4-aminophenylfluorene) (BAFL), 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 4-aminobenzoic acid-4-aminophenyl ester (APAB), 2-(4-aminophenyl)-5-aminobenzoxazole, 4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy) Benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4-bis(4-aminophenoxy)biphenyl (BAPB), 4,4-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 9,10-bis(4-aminophenyl)anthracene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)]hexafluoropropane, Diamines include 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 1,4-bis(3-aminopropyldimethylsilyl)benzene, 1,3-bis[1-(4-aminophenyl)-1-methylethyl]benzene (BiSAM), 1,4-cyclohexanediamine (CHDA), 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (TFOMB), and 2,2”-bis(trifluoromethyl)[1,1':4',1”-terphenyl]-4,4”-diamine, etc. These diamines can be used alone or in combination of two or more.

[0375] In the above general formulas (I) and (II), P1 preferably contains at least one structural unit derived from the diamines shown in the following general formulas (3) to (12).

[0376]

[0377]

[0378] The content of structures derived from the above-mentioned diamine compounds in all diamines (excluding compounds in general formula (13) where L1 and L2 are amino groups) may be 20 mol% or more, 40 mol% or more, 50 mol% or more, 70 mol% or more, 90 mol% or more, or 95 mol% or more.

[0379] (acid dianhydride)

[0380] Examples of acid dianhydrides containing the P2 group in general formulas (I) and (II) include pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic anhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, methylene-4, 4'-Diphthalic anhydride, 1,1-Ethylene-4,4'-Diphthalic anhydride, 2,2-Propylene-4,4'-Diphthalic anhydride, 1,2-Ethylene-4,4'-Diphthalic anhydride, 1,3-Trimethylene-4,4'-Diphthalic anhydride, 1,4-Tetramethylene-4,4'-Diphthalic anhydride, 1,5-Pentamethylene-4,4'-Diphthalic anhydride, 4,4'-Oxyphthalic anhydride (ODPA), p-Phenylidene bis(triphenylene anhydride), Thio-4,4'-Diphthalic anhydride, Sulfonyl-4,4'-Diphthalic anhydride, 1,3-Bis(3,4-dicarboxyphenylene) 1,3-bis(3,4-dicarboxyphenoxy)phenyl dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phenyl dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phenyl dianhydride, 1,4-bis[2-(3,4-dicarboxyphenyl)-2-propyl]phenyl dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride Examples of dianhydrides include 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracitetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride (CpODA), 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride (HPMDA), and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA). These dianhydrides can be used alone or in combination of two or more.

[0381] <Silicon-containing compounds>

[0382] The polyamic acid, polyamic acid-imide copolymer, polyimide copolymer, polyimide precursor or polyimide resin described above may contain the structure shown in the following general formula (14).

[0383]

[0384] {In the formula, when there are multiple R1 and R2, each independently represents a monovalent aliphatic hydrocarbon group with 1 to 5 carbon atoms or a monovalent aromatic group with 6 to 10 carbon atoms, and m represents an integer from 1 to 200}.

[0385] When the structure includes the general formula (14), the resulting polyimide film has good Rth and residual stress, and is therefore preferred.

[0386] In order for the resin to have the structure of general formula (14), X1 to X4 in general formulas (1) and (2) above or P1 or P2 in general formulas (I) and (II) above may contain structural units derived from silicon-containing compounds shown in general formula (13) below.

[0387]

[0388] {In the formula, R1 is independently a single bond or a divalent organic group having 1 to 10 carbon atoms; R2 and R3 are independently monovalent organic groups having 1 to 10 carbon atoms, and at least one is a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms; R4 and R5 are independently monovalent organic groups having 1 to 10 carbon atoms, and at least one is a monovalent aromatic group having 6 to 10 carbon atoms; R6 and R7 are independently monovalent organic groups having 1 to 10 carbon atoms; L1 and L2 are independently amino, anhydride, isocyanate, carboxyl, ester, acyl halide, hydroxyl, epoxy, or mercapto groups; i is an integer from 1 to 200; j and k are independently integers from 0 to 200; 0 ≤ j / (i+j+k) ≤ 0.50; and the functional group equivalent is 800 or more.}

[0389] In the resin composition, when the diamine is set to 100 mol%, the silicon-containing compound represented by the above general formula (13) is 20 mol% or less; or, when the acid dianhydride is set to 100 mol%, the silicon-containing compound represented by the above general formula (13) is 20 mol% or less. When the silicon-containing compound is within the above range, it is preferable from the viewpoint of the filterability of the obtained polyimide precursor or polyimide resin composition. From the viewpoint of further improving filterability, when all the diamine or all the acid dianhydride in the resin composition is set to 100 mol%, the silicon-containing compound is more preferably 20.0 mol% or less, 19.0 mol% or less, 18.0 mol% or less, 17.0 mol% or less, 16.0 mol% or less, 15.0 mol% or less, or 14.0 mol% or less. When all the diamine or all the acid dianhydride in the resin composition is set to 100 mol%, the silicon-containing compound may exceed 0 mol%.

[0390] In formula (13), R1 is each independently a single bond or a divalent organic group having 1 to 10 carbon atoms. The divalent organic group having 1 to 10 carbon atoms can be any of straight-chain, cyclic, or branched, and can be saturated or unsaturated. Examples of divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms include, for example, methylene, methylene-propylene, isopropylene, n-butylene, sec-butylene, tert-butylene, n-pentylene, neopentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decyl, etc., which are straight-chain or branched alkylene groups; and cycloalkylene groups such as cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, etc. As a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, at least one of the group consisting of ethylene, n-propylene, and isopropylene is preferred.

[0391] In formula (13), R2 and R3 are each an organic group with 1 to 10 carbon atoms and a monovalent organic group, and at least one of them is an aliphatic hydrocarbon group with 1 to 5 carbon atoms and a monovalent organic group.

[0392] Organic groups with 1 to 10 carbon atoms and a monovalent charge can be any of the following: straight-chain, cyclic, or branched; and can be saturated or unsaturated. Examples of monovalent organic groups with 1 to 10 carbon atoms include straight-chain or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; and aromatic groups such as phenyl, tolyl, xylyl, α-naphthyl, and β-naphthyl.

[0393] The monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms can be any of the following: straight-chain, cyclic, or branched; and can be saturated or unsaturated. Examples of monovalent aliphatic hydrocarbon groups having 1 to 5 carbon atoms include straight-chain or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, and neopentyl; and cycloalkyl groups such as cyclopropyl, cyclobutyl, and cyclopentyl. Preferably, at least one aliphatic hydrocarbon group having 1 to 5 carbon atoms is selected from the group consisting of methyl, ethyl, and n-propyl.

[0394] In formula (13), R4 and R5 are each independently a monovalent organic group having 1 to 10 carbon atoms, and at least one is a monovalent aromatic group having 6 to 10 carbon atoms. The monovalent organic group having 1 to 10 carbon atoms can be any of the following: linear, cyclic, or branched, and can be saturated or unsaturated. For example, examples of monovalent organic groups having 1 to 10 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; and aromatic groups such as phenyl, tolyl, xylyl, α-naphthyl, and β-naphthyl. Examples of monovalent aromatic groups with 6 to 10 carbon atoms include phenyl, tolyl, xylyl, α-naphthyl, β-naphthyl, etc., with phenyl, tolyl or xylyl being preferred.

[0395] In formula (13), R6 and R7 are each independently a monovalent organic group having 1 to 10 carbon atoms, and at least one is preferably an organic group having an unsaturated aliphatic hydrocarbon group. The monovalent organic group having 1 to 10 carbon atoms can be any of straight-chain, cyclic, or branched. Examples of monovalent organic groups having 1 to 10 carbon atoms include straight-chain or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl; and aromatic groups such as phenyl, tolyl, xylyl, α-naphthyl, and β-naphthyl. Preferably, at least one of the group consisting of methyl, ethyl, and phenyl is selected as the monovalent organic group having 1 to 10 carbon atoms.

[0396] The organic group having an unsaturated aliphatic hydrocarbon group can be an unsaturated aliphatic hydrocarbon group having 3 to 10 carbon atoms, and can be any of straight-chain, cyclic, or branched. Examples of unsaturated aliphatic hydrocarbon groups having 3 to 10 carbon atoms include vinyl, allyl, 1-propenyl, 3-butenyl, 2-butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, octenyl, nonenyl, decenyl, ethynyl, propynyl, butynyl, penynyl, and hexynyl. Preferably, at least one of the groups consisting of vinyl, allyl, and 3-butenyl is selected as the unsaturated aliphatic hydrocarbon group having 3 to 10 carbon atoms.

[0397] In formula (13), some or all of the hydrogen atoms of R1 to R7 can be replaced by substituents such as halogen atoms such as F, Cl, and Br, or they can remain unsubstituted.

[0398] In formula (13), L1 and L2 are each independently a monovalent organic group (also called an anhydride group), amino, isocyanate group, carboxyl group, alkoxy carbonyl group, halocarbonyl group, hydroxyl group, epoxy group or mercapto group containing an anhydride structure.

[0399] Examples of monovalent organic groups containing an anhydride structure include, for example, 2,5-dioxatetrahydrofuran-3-yl, as shown in the following formula.

[0400]

[0401] In the above formula, "*" represents an atomic bond.

[0402] Among these, amino and anhydride groups are preferred, and amino groups are more preferred from the viewpoint of viscosity stability of the resin composition.

[0403] The alkoxy group in the alkoxy carbonyl group can be an alkoxy group with 1 to 6 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, etc.

[0404] The halogen atom in the halogenated carbonyl group is preferably a halogen atom other than a fluorine atom, and more preferably a chlorine atom or an iodine atom.

[0405] From the viewpoint of the filterability of the resin composition, the functional group equivalent of the silicon-containing compound shown in formula (13) is preferably 800 or more, more preferably 1000 or more, and even more preferably 1500 or more. On the other hand, when the functional group equivalent is 500 or less, the filterability may sometimes deteriorate. Here, the functional group equivalent refers to the molecular weight (unit: g / mol) of the silicon-containing compound per mol of functional groups. The functional group equivalent can be determined by known methods according to existing standards, etc. In addition, when the functional group equivalent of the silicon-containing compound is 800 or more, the residual stress of the polyimide film under a nitrogen atmosphere is small, which is therefore preferred. This is because when the functional group equivalent is above a certain value, the number of organosilicon structural domains increases, resulting in stress relaxation.

[0406] In equation (13), i is an integer from 1 to 200, preferably an integer from 2 to 100, more preferably an integer from 4 to 80, and even more preferably an integer from 8 to 40. j and k are each independently an integer from 0 to 200. j can be an integer from 1 to 200, and j and k are preferably integers from 0 to 50, more preferably integers from 0 to 20, and even more preferably integers from 0 to 50.

[0407] When the resin in the resin composition has a structure derived from formula (13), the residual stress of the polyimide film measured under a nitrogen atmosphere is good (small), and therefore preferred. The reason for measuring under a nitrogen atmosphere is that in the process of display manufacturing, there are cases where inorganic films such as SiO and SiN are exposed to a nitrogen atmosphere when forming on the polyimide film, and it is necessary to have low residual stress under a nitrogen atmosphere.

[0408] From the perspectives of monomer type, cost, and molecular weight of the resulting polyimide precursor, L1 and L2 in general formula (13) are each preferably amino groups. That is, the silicon-containing compound of general formula (13) is preferably a silanediamine. As a silanediamine, for example, a diamino (poly)siloxane represented by the following general formula (15) is preferred.

[0409]

[0410] {In the formula, P5 independently represents a divalent hydrocarbon group, which may be the same or different; P3 and P4 are the same as R2 and R3 as defined in general formula (13); and l represents an integer from 1 to 200.}

[0411] Preferred structures for P3 and P4 in the above general formula (15) include methyl, ethyl, propyl, butyl, and phenyl. Among these, methyl is preferred.

[0412] In the above general formula (15), l is an integer from 1 to 200. From the viewpoint of the heat resistance of polyimide obtained by using the silicon-containing diamine shown in formula (15), an integer from 3 to 200 is preferred.

[0413] The preferred range of functional group equivalents of the compounds represented by general formula (15) is the same as that of the silicon-containing compounds represented by general formula (13) above.

[0414] When the total mass of all monomers (polyimide precursor / total mass of polyimide) is set to 100% by mass, the content (copolymerization ratio) of the silicon-containing compound shown in general formula (13) is preferably 0.5% by mass or more and 20% by mass or less.

[0415] When the silicon-containing compound content is 0.5% by mass or more, the residual stress generated between the silicon-containing compound and the support can be effectively reduced. When the silicon-containing compound content is 20% by mass or less, the resulting polyimide film has good transparency (especially low haze), which is preferred from the viewpoint of achieving high total light transmittance and high glass transition temperature.

[0416] Silicon-containing compounds used as precursors / monomers in polyimides can be synthesized using the technical knowledge available at the time of application, as described above, or commercially available products can be used. Examples of commercially available products include: amine-terminated methylphenyl silicone oil (Shin-Etsu Chemical Co., Ltd.: X22-1660B-3 (functional equivalent 2200), X22-9409 (functional equivalent 670)); anhydride-terminated methylphenyl silicone oil (Shin-Etsu Chemical Co., Ltd.: X22-168-P5-B (functional equivalent 2100)); and epoxy-terminated methylphenyl silicone oil (Shin-Etsu Chemical Co., Ltd.: X22-2000). (functional group equivalent 620)), two-terminated amino-modified dimethyl organosilicon (Shin-Etsu Chemical Co., Ltd.: PAM-E (functional group equivalent 130), X22-161A (functional group equivalent 800), X22-161B (functional group equivalent 1500), KF8012 (functional group equivalent 2200), Toray Dow Corning Co., Ltd.: BY16-853U (functional group equivalent 450), JNC Co., Ltd.: Silaplane Among these, FM3311 (number average molecular weight 1000), two-terminated epoxy-modified dimethyl silicone oils (Shin-Etsu Chemical Co., Ltd.: X-22-163A (functional group equivalent 1750), two-terminated alicyclic epoxy-modified dimethyl silicone oils (Shin-Etsu Chemical Co., Ltd.: X-22-169B (functional group equivalent 1700)), two-terminated hydroxyl-modified dimethyl silicone oils (Shin-Etsu Chemical Co., Ltd.: KF-6000), two-terminated mercapto-modified dimethyl silicone oils (Shin-Etsu Chemical Co., Ltd.: X-22-167B (functional group equivalent 1700)), and two-terminated anhydride-modified dimethyl silicone oils (Shin-Etsu Chemical Co., Ltd.: X-22-168A (functional group equivalent 1000)) are preferred, considering price, improved chemical resistance, and increased Tg.

[0417] (d) Organic solvents

[0418] (d) There are no particular limitations on the organic solvent, as long as it can dissolve (a) polyamic acid, (b) polyimide, (c) polyamic acid-imide copolymer, and other optional components. Specific examples of such (d) organic solvents include, for example, aprotic solvents, phenolic solvents, ether and glycol solvents.

[0419] From the viewpoint of improving the in-plane uniformity of film thickness and reducing the YI value, the aprotic solvent is preferably polar and / or preferably has a boiling point of 250°C to 350°C, for example, it can be an aprotic polar substance with a boiling point of 250°C to 350°C as described later.

[0420] Examples of nonprotic solvents include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N-methylcaprolactam, 1,3-dimethylimidazolinone, tetramethylurea, and amide solvents of the following general formulas; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphonic triamide; sulfur-containing solvents or compounds containing sulfone structures such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as cyclohexanone and methylcyclohexanone; tertiary amine solvents such as methylpyridine and pyridine; and ester solvents such as (2-methoxy-1-methylethyl) acetate.

[0421]

[0422] In the formula, R 12 =Methyl 3-methoxy-N,N-dimethylpropionamide (manufactured by KJ CHEMICALS, trade name: Examid M100) and R 12 =3-Butoxy-N,N-Dimethylpropionamide (manufactured by KJ CHEMICALS, trade name: Examid B100) as shown by n-butyl

[0423] Among these, the aprotic polar solvent preferably includes one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, 3-methoxy-N,N-dimethylpropionamide, γ-butyrolactone, γ-valerolactone, and sulfolane, more preferably sulfolane.

[0424] Examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Examples of ether and glycol solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane.

[0425] From the viewpoint of the solubility of polyamic acid, polyimide and polyamic acid-imide copolymer, (d) the organic solvent preferably includes at least one selected from NMP, GBL, DMF and DMAc.

[0426] [Other ingredients]

[0427] In addition to the components (a), (b), (c) and (d) above, the resin composition may also contain (e) an imidization catalyst, an aprotic polar substance, a surfactant, and an alkoxysilane compound.

[0428] (e) imidization catalyst)

[0429] In the process of obtaining a polyimide resin film by imidization of a resin composition, an imidization catalyst may be added to the resin composition.

[0430] In this resin composition, 0.01 to 0.5 mol% of imidizing catalyst may be contained per mole of repeating unit (c) of polyamic acid-imide copolymer. The imidizing catalyst content is 0.01 mol% or more per mole of repeating unit of polyamic acid-imide copolymer, thereby suppressing the yellowness (YI value) of the film. Furthermore, from the viewpoint of the storage stability of the resin composition, the imidizing catalyst content is preferably 0.5 mol% or less. The imidizing catalyst content is preferably 0.015 to 0.5 mol% per mole of repeating unit of polyamic acid-imide copolymer, more preferably 0.02 to 0.5 mol%, and particularly preferably 0.02 to 0.15 mol%.

[0431] From the viewpoint of the effect of the present invention, (e) the content of the imidization catalyst is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, relative to 100 parts by mass of the polyamic acid-imide copolymer or polyamic acid described above.

[0432] As an imidization catalyst, there are no particular limitations, and examples include pyridine, triethylamine, 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, benzimidazole, N-tert-butoxycarbonylimidazole (N-Boc-imidazole), etc. Furthermore, from the viewpoint of the effectiveness of the present invention, imidization catalysts preferably include imidazole compounds such as 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, 2-phenylimidazole, imidazole, benzimidazole, or N-tert-butoxycarbonylimidazole (N-Boc-imidazole), more preferably 1,2-dimethylimidazole, 1-methylimidazole, 2-methylimidazole, imidazole, etc., even more preferably 1,2-dimethylimidazole, N-tert-butoxycarbonylimidazole (N-Boc-imidazole), 1-methylimidazole, etc., and even more preferably imidazole compounds containing N-tert-butoxycarbonylimidazole (N-Boc-imidazole) and / or 1-methylimidazole. From the viewpoint of storage stability, N-Boc-imidazole is particularly preferred, and from the viewpoint of yellowness (YI value) at high temperature, 1-methylimidazole is particularly preferred.

[0433] In addition, there are no particular limitations on imidization catalysts; nitrogen-containing compounds can be listed, specifically imidazole compounds, pyridine compounds, tertiary amine compounds, etc.

[0434] Examples of imidazole compounds include 1-methylimidazolium, N-tert-butoxycarbonylimidazolium (N-Boc-imidazolium), 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, 2-ethyl-4-methylimidazolium, 4-ethyl-2-methylimidazolium, 4-methyl-2-phenylimidazolium, 2-undecylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1H-imidazolium, and 1,2-dimethylimidazolium.

[0435] Examples of pyridine compounds include 4-dimethylaminopyridine, 2,2'-bipyridine, nicotinic acid, isoquinoline, pyridine, and 2-methylpyridine.

[0436] Examples of tertiary amine compounds include 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, and triethylamine.

[0437] These compounds can also be used in combination of two or more.

[0438] From the perspective of evaluating IR (infrared) curing defects and degassing, as described later, 1-methylimidazole, N-tert-butoxycarbonylimidazole (N-Boc-imidazole), 2-methylimidazole, 2-phenylimidazole, benzimidazole, 2-ethyl-4-methylimidazole, 4-ethyl-2-methylimidazole, 4-methyl-2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 4-dimethylaminopyridine as a pyridine compound, 2,2'-bipyridine, nicotinic acid, isoquinoline, 2-methylpyridine, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane and N-methylmorpholine are preferred, and 1-methylimidazole and N-tert-butoxycarbonylimidazole (N-Boc-imidazole) are more preferred.

[0439] Regarding the content of the imidization catalyst, from the perspective of IR (infrared) curing defect evaluation and degassing evaluation, it is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, relative to 100 parts by mass of polyamic acid-imide copolymer or polyamic acid.

[0440] The evaluation of IR (infrared) curing defects described below can be improved by employing any one or more of the following: a. to c.

[0441] a. Using an imidization catalyst as an additive;

[0442] b. Use non-protic polar substances with a boiling point of 250-350°C as additives;

[0443] c. Increasing the molecular weight of polyamic acid-imide copolymers / polyamic acid.

[0444] The mechanism for improving the curing process is not yet determined, but it is believed to be related to the promotion of imidization. Specifically, the cause of IR curing defects is considered to be the formation of oligomers, which are related to their decomposition due to infrared radiation. It is believed that imidization is promoted by methods a. and b., while oligomer formation is inhibited. Furthermore, regarding method c., it is believed that increasing the molecular weight results in the inhibition of oligomer formation.

[0445] Furthermore, the degassing evaluation described below can be improved by employing any one or more of the following a. to c.:

[0446] a. Using an imidization catalyst as an additive;

[0447] b. Use non-protic polar substances with a boiling point of 250-350°C as additives;

[0448] c. Increasing the molecular weight of polyamic acid-imide copolymers / polyamic acid.

[0449] The mechanism for improvement is not yet determined, but it is believed to be related to the promotion of imidization. Specifically, the degassing is thought to be related to the presence of low molecular weight components / oligomers in the polyimide film after curing, which is attributed to the promotion of imidization and the inhibition of low molecular weight components / oligomer formation through methods a. and b. Furthermore, regarding c., it is believed that increasing the molecular weight would result in the suppression of low molecular weight component / oligomer residue.

[0450] (f) Non-protic polar substances with boiling points of 250-350℃

[0451] One aspect of the resin composition disclosed herein comprises an aprotic polar substance having a boiling point of 250°C to 350°C. Preferably, the aprotic polar substance having a boiling point of 250°C to 350°C is a compound having a boiling point of 250°C to 350°C, and is free of OH, NH2, NH, and SH groups, and has at least one chemical structure (functional group) selected from ketones, esters, carbonates, amides, nitriles, sulfoxides, and sulfones.

[0452] If we specifically list the preferred compounds, for example, compounds with a ketone structure and a boiling point of 250°C to 350°C, we can list benzophenone, methyl benzophenone, dimethyl benzophenone, dodecanedione, etc.

[0453] Examples of compounds with an ester structure and a boiling point of 250℃~350℃ include dibutyl sebacate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, 2-phenoxyethyl acetate, butyl benzoate, isoamyl benzoate, dibutyl maleate, ethyl cinnamate, diethylene glycol diacetate, and diethyl adipate.

[0454] Examples of compounds with carbonate structures and boiling points of 250℃ to 350℃ include diphenyl carbonate, etc.

[0455] Examples of compounds with an amide structure that have a boiling point of 250℃ to 350℃ include benzamide, N,N-dimethylbenzamide, and adipamide.

[0456] Examples of compounds with a nitrile structure that have a boiling point of 250℃ to 350℃ include adiponitrile, etc.

[0457] Examples of compounds with a sulfoxide structure and a boiling point of 250℃~350℃ include dibutyl sulfoxide and diphenyl sulfoxide.

[0458] Examples of compounds with a sulfone structure and a boiling point of 250℃ to 350℃ include sulfolane, 3-methylsulfolane, dibutyl sulfone, and benzenesulfonamide.

[0459] Among these compounds, sulfolane and 3-methylsulfolane are preferred.

[0460] Adding an aprotic polar substance with a boiling point of 250°C to 350°C, either alone or together with a solvent, to a polyamic acid-imide copolymer or a polyamide precursor during coating / curing (heating) can improve the evaluation of IR curing defects and degassing. This effect is particularly significant when the amount of (solvent mass + aprotic polar substance mass) is set to 100 wt%, and the addition amount is 5 wt% or more. As an upper limit for the amount of aprotic polar substance added, when (solvent mass + aprotic polar substance mass) is set to 100 wt%, the upper limit is 100 wt%, and a more preferred addition amount is 30 wt% or less.

[0461] (Aprotic polar substances with a boiling point of 250℃~350℃)

[0462] The resin composition preferably contains an aprotic polar substance with a boiling point of 250°C to 350°C.

[0463] The preferred aprotic polar substance with a boiling point of 250℃ to 350℃ is a compound with a boiling point of 250℃ to 350℃ that does not contain OH, NH2, NH, or SH groups and has at least one chemical structure (functional group) selected from ketones, esters, carbonates, amides, nitriles, sulfoxides, and sulfones. The aprotic polar substance can be used in conjunction with the aprotic solvents described above, provided its boiling point is between 250℃ and 350℃.

[0464] If we specifically list the preferred compounds, for example, compounds with a ketone structure and a boiling point of 250°C to 350°C, we can list benzophenone, methyl benzophenone, dimethyl benzophenone, dodecanedione, etc.

[0465] Examples of compounds with an ester structure and a boiling point of 250℃~350℃ include dibutyl sebacate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, 2-phenoxyethyl acetate, butyl benzoate, isoamyl benzoate, dibutyl maleate, ethyl cinnamate, diethylene glycol diacetate, and diethyl adipate.

[0466] Examples of compounds with carbonate structures and boiling points of 250℃ to 350℃ include diphenyl carbonate, etc.

[0467] Examples of compounds with an amide structure that have a boiling point of 250℃ to 350℃ include benzamide, N,N-dimethylbenzamide, and adipamide.

[0468] Examples of compounds with a nitrile structure that have a boiling point of 250℃ to 350℃ include adiponitrile, etc.

[0469] Examples of compounds with a sulfoxide structure and a boiling point of 250℃~350℃ include dibutyl sulfoxide and diphenyl sulfoxide.

[0470] Examples of compounds with a sulfone structure and a boiling point of 250℃ to 350℃ include sulfolane, 3-methylsulfolane, dibutyl sulfone, and benzenesulfonamide.

[0471] Among these compounds, sulfolane and 3-methylsulfolane are preferred.

[0472] When a non-protic polar substance with a boiling point of 250℃~350℃ is added to a polyamide precursor, or a resin having a polyamide precursor and a polyimide structure, or a solvent-soluble polyimide, alone or together with a solvent, and then coated / cured (heated), the in-plane film thickness uniformity of the cured film can be improved and the YI can be reduced compared to when no substance is added. When (mass of solvent + mass of non-protic polar substance) is set to 100wt%, the effect is particularly significant when more than 5wt% is added.

[0473] Aprotic polar substances with boiling points of 250℃ to 350℃ remain in the film even at temperatures above 250℃ during the curing process of polyimide (heating to around 400℃), acting as plasticizers at high temperatures. Therefore, it is believed that in the temperature range above 250℃ during the curing process, the resin is soft, maintains fluidity, improves the in-plane uniformity of film thickness, and reduces YI. On the other hand, when the amount of aprotic polar substances with boiling points of 250℃ to 350℃ is large, they cannot all volatilize during curing, leaving a small amount in the cured film. In the manufacturing process of flexible displays, the following situation exists: an inorganic film such as silicon nitride is formed on the cured film using CVD, etc., and an amorphous silicon or low-temperature polycrystalline silicon layer is formed on top of it. The same temperature as the curing temperature is then applied again (a re-annealing process). When the cured film contains residual aprotic polar substances with boiling points of 250℃ to 350℃, they volatilize during re-annealing, causing the inorganic film formed on the film to bulge. To prevent this, the residual amount of this substance in the film needs to be suppressed to below 1000 ppm.

[0474] Therefore, as the upper limit for the amount of aprotic polar substance added, in the case of polyimide precursors or resins having both a polyimide precursor backbone and a polyimide backbone, the upper limit is 100 wt% when (mass of solvent + mass of aprotic polar substance) is set to 100 wt%.

[0475] In the case of solvent-soluble polyimides containing a solvent in addition to the polyimide precursor or a resin having a polyimide precursor backbone and a polyimide backbone, the upper limit is 50 wt% when (mass of solvent + mass of aprotic polar substance) is set to 100 wt%.

[0476] In the case of polyimide precursors or resins having both a polyimide precursor backbone and a polyimide backbone, and in the case of solvent-soluble polyimides, the addition amount is further preferably 30 wt% or less.

[0477] Among aprotic polar substances, sulfolane and 3-methylsulfolane exhibit excellent effects in improving the in-plane uniformity of the cured film and reducing YI. Although other substances also show similar effects, the effect is more pronounced when using sulfolane and 3-methylsulfolane.

[0478] When the boiling point of aprotic polar substances is below 250°C, they do not show any effect in improving the in-plane uniformity of the cured film or reducing YI. When the boiling point is above 350°C, although they show an effect, the residue in the cured film exceeds 1000 ppm, which is not preferred from the perspective of degassing.

[0479] (surfactant)

[0480] By adding surfactants to the resin composition, the coatability of the resin composition can be improved. Specifically, it can prevent streaks from forming in the coated film.

[0481] Examples of such surfactants include silicone surfactants, fluorinated surfactants, and other nonionic surfactants. Examples of silicone surfactants include organosiloxane polymers such as KF-640, 642, 643, KP341, X-70-092, X-70-093 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.); SH-28PA, SH-190, SH-193, SZ-6032, SF-8428, DC-57, DC-190 (trade name, manufactured by Toray Dow Corning Silicones Co., Ltd.); SILWETL-77, L-7001, FZ-2105, FZ-2120, FZ... -2154, FZ-2164, FZ-2166, L-7604 (trade name, manufactured by Unicharm Japan); DBE-814, DBE-224, DBE-621, CMS-626, CMS-222, KF-352A, KF-354L, KF-355A, KF-6020, DBE-821, DBE-712 (Gelest), BYK-307, BYK-310, BYK-378, BYK-333 (trade name, manufactured by BYK-Chemie Japan); GRANOL (trade name, manufactured by Kyoei Chemical Co., Ltd.), etc. Examples of fluorinated surfactants include Megafac F171, F173, and R-08 (manufactured by Dai Nippon Ink Chemical Industry Co., Ltd., trade name); Fluorad FC4430 and FC4432 (Sumitomo 3M Co., Ltd., trade name), etc. Other examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octylphenol ether, etc.

[0482] Among these surfactants, from the viewpoint of improving the coatability of the resin composition (suppressing streaks), silicone-based surfactants and fluorinated surfactants are preferred. From the viewpoint of reducing the influence of oxygen concentration during the curing process on the YI value and total light transmittance, silicone-based surfactants are preferred. When using surfactants, the amount of surfactant mixed is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, relative to 100 parts by weight of the polyimide precursor in the resin composition.

[0483] (Alkoxysilane compounds)

[0484] When a polyimide film obtained from a resin composition is used in a flexible substrate or the like, from the viewpoint of achieving good adhesion between the support and the polyimide film during the manufacturing process, the resin composition may contain 0.01 to 20 parts by mass of an alkoxysilane compound relative to 100 parts by mass of the polyimide precursor. By making the content of the alkoxysilane compound 0.01 parts by mass or more relative to 100 parts by mass of the polyimide precursor, good adhesion between the support and the polyimide film can be achieved. Furthermore, from the viewpoint of the storage stability of the resin composition, the content of the alkoxysilane compound is preferably 20 parts by mass or less. The content of the alkoxysilane compound relative to 100 parts by mass of the polyimide precursor is preferably 0.02 to 15 parts by mass, more preferably 0.05 to 10 parts by mass, and even more preferably 0.1 to 8 parts by mass. By using alkoxysilane compounds, the coating properties of the resin composition are improved (suppressing uneven streaks) in addition to the improved adhesion. Furthermore, the effect of oxygen concentration during curing on the YI value of the polyimide film is also reduced.

[0485] Examples of alkoxysilane compounds include, for example, 3-ureidopropyltriethoxysilane, bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltripropoxysilane, γ-aminopropyltributoxysilane, γ-aminoethyltriethoxysilane, γ-aminoethyltripropoxysilane, γ-aminoethyltributoxysilane, γ-aminobutyltriethoxysilane, γ-aminobutyltrimethoxysilane, γ-aminobutyltripropoxysilane, γ-aminobutyltributoxysilane, phenylsilanetriol, trimethoxyphenylsilane, trimethoxy(p-tolyl)silane, diphenylsilanediol, dimethoxydiphenylsilane, diethoxydiphenylsilane, dimethoxydi-p-tolylsilane, triphenylsilanol, and alkoxysilane compounds with the structures shown below.

[0486]

[0487] Alkoxysilane compounds can be used alone or in combination of two or more.

[0488] [Manufacturing method of polyamic acid-imide copolymer]

[0489] The polyamic acid, polyimide, and polyamic acid-imide copolymer of the present invention can be synthesized by a manufacturing method comprising the following steps. For example, the manufacturing method of the polyamic acid-imide copolymer includes steps 1 to 3 as follows:

[0490] Step 1: A step of reacting the tetracarboxylic acid dianhydride component (X3) constituting the polyamic acid portion of the above general formula (1) with the diamine component (X4) to obtain a solvent-soluble polyimide solution;

[0491] Step 2: The step of dissolving the diamine (X2) of the polyamic acid portion of the above general formula (1) in the polyimide obtained in Step 1; and

[0492] Step 3: A step of reacting the tetracarboxylic acid dianhydride component (X1) constituting the polyamic acid portion of the above general formula (1) with the solution obtained in step 2 to obtain a polyamic acid-imide copolymer.

[0493] First, specific embodiments will be described sequentially starting from step 1. Step 1 is the step of synthesizing the polyimide portion of the above general formula (1). It can be synthesized by polycondensation reaction of the diamine (e.g., 44BAFL) of the polyimide portion of the above general formula (1) with a tetracarboxylic acid dianhydride (e.g., BPAF). This reaction is preferably carried out in a reaction vessel in which water generated during imidization can be removed, and in a solvent capable of dissolving the monomer and purifying the polyimide. Specifically, the following method can be used as an example: a predetermined amount of BAFL and NMP are added to a detachable flask equipped with a reflux tube and a Dean-Stock tube, and after the BAFL is completely dissolved, a predetermined amount of BPAF and toluene as an azeotropic solvent for water are added, and the mixture is heated to 180°C and stirred. The water generated during heating at 180°C and the toluene as an azeotropic solvent are preferably appropriately drained out of the container.

[0494] Regarding the molar ratio (tetracarboxylic dianhydride to diamine) in the synthesis of the aforementioned polyimide precursor, from the viewpoint of controlling the coefficient of thermal expansion, residual stress, elongation, and yellowness (hereinafter also referred to as YI) of the obtained resin film within the desired range, it is preferably set to a range of tetracarboxylic dianhydride:diamine = 100:85 to 100:200 (0.85 to 2.00 moles of diamine relative to 1 mole of tetracarboxylic dianhydride), more preferably a range of 100:101 to 100:125 (1.01 to 1.25 moles of diamine relative to 1 mole of tetracarboxylic dianhydride). Setting it to the above range is preferred from the perspective of easier reaction with polyamic acid and reduced haze.

[0495] From the viewpoint of balancing imidization and water removal, a reaction temperature of 140°C or higher is preferred, and 160°C is more preferred. Furthermore, from the viewpoint of suppressing coloration caused by solvent decomposition and reaction with monomers, a reaction temperature of 200°C or lower is preferred, and 190°C or lower is more preferred. After the reaction is complete, the temperature is preferably rapidly reduced to 100°C or lower.

[0496] From the viewpoint of increasing molecular weight, a reaction time of 2 hours or more, preferably 3 hours or more, is preferred. On the other hand, from the viewpoint of suppressing coloration caused by solvent decomposition and reaction with monomers, a reaction time of 12 hours or less, more preferably 6 hours or less, is preferred.

[0497] Next, step 2 will be described. Step 2 is a step of dissolving the polyamic acid portion of the polyimide obtained in step 1 above into the diamine (X2) of the above general formula (1). After the polyimide is synthesized in step 1, a specified amount of diamine (e.g., APAB) and NMP are added and stirred thoroughly to dissolve the diamine. From the viewpoint of controlling the coefficient of thermal expansion, residual stress, elongation, and yellowness (hereinafter also referred to as YI) of the final polyimide copolymer film within the desired range, it is preferable to set the ratio of the component derived from tetracarboxylic dianhydride in the polyimide portion (X3) to the components derived from diamine in the polyimide portion and the polyamic acid portion (X2 and X4) in the diamine portion to the polyimide portion to the diamine portion to the polyamic acid portion to the polyimide portion to the diamine ... By setting the reaction within the above range, the reaction uniformity is improved when tetracarboxylic acid dianhydride reacts in step 3, resulting in a polyamic acid-imide copolymer with a low ratio of oligomers with a molecular weight distribution close to 2.00 and a molecular weight below 1,000. This improves the thermal stability in high-temperature regions when the film is made.

[0498] From the viewpoint of improving the solubility and uniformity of the diamine, a temperature of 40°C or higher is preferred, and more preferably 60°C or higher. On the other hand, from the viewpoint of suppressing coloration caused by side reactions with the solvent, a temperature of 120°C or lower is preferred, and more preferably 100°C or lower.

[0499] Next, step 3 will be explained. In step 3, the solution obtained by dissolving polyimide and diamine in step 2 above is added to the tetracarboxylic acid dianhydride of the polyamic acid part in the above general formula (1) to carry out a polycondensation reaction, thereby synthesizing a polyamic acid-imide copolymer.

[0500] As a method for manufacturing polyamic acid-imide copolymers that includes steps different from those described in steps 1 to 3 above, a manufacturing method described in International Publication No. 2020 / 138360 is known. Specifically, the imidization step in step 1 above includes a step of simultaneously imidizing diamine compounds equivalent to X2 and X4, and diamine compounds commonly used in X2 and X4 can be used.

[0501] However, the inventors have confirmed that when using the same manufacturing method as that described in International Publication No. 2020 / 138360, specifically when using diamines of general formula (B-1) or (B-2) as raw materials in the imide synthesis of step 1, the molecular weight cannot be sufficiently increased, and an evaluable polyamic acid-imide copolymer cannot be obtained. This is believed to be because the diamines represented by general formulas (B-1) and (B-2) are highly reactive and lack thermal stability in high-temperature solvents. When heated at high temperatures (approximately 180°C) with an excess of amine relative to acid, the diamines become deactivated due to reactions with solvents or oxygen, thus failing to sufficiently increase the molecular weight in subsequent steps for the synthesis of polyamic acid-imide copolymers.

[0502] Specifically, a reproduction test was conducted under the same conditions as the examples in International Publication No. 2020 / 138360, resulting in an NMP solution (hereinafter also referred to as varnish) of the polyimide-polyamic acid copolymer. The results confirmed that the obtained polyamic acid-imide copolymer had a weight-average molecular weight (Mw) of 2,638 and a number-average molecular weight (Mn) of 1,326. Therefore, from the viewpoint of the copolymer's molecular weight, the manufacturing method including steps 1 to 3 described above is preferred over the manufacturing method described in International Publication No. 2020 / 138360.

[0503] Regarding the molar ratio (X2 / X1) of the tetracarboxylic dianhydride component (X1) to the diamine component (X2) in the synthesis of the above-mentioned polyamic acid-imide copolymer, from the viewpoint of controlling the coefficient of thermal expansion, residual stress, elongation, and YI of the obtained resin film within the desired range, it is preferably 0.85 to 1.2, more preferably 0.90 to 1.1, and even more preferably 0.92 to 1.00. Setting it to the above range is preferable in terms of facilitating the reaction with polyimide and reducing haze.

[0504] Furthermore, regarding the molar ratio (X4 / X3) of the tetracarboxylic dianhydride component (X3) to the diamine component (X4) in the polyimide portion during the synthesis of the aforementioned polyamic acid-imide copolymer, from the viewpoint of controlling the coefficient of thermal expansion, residual stress, elongation, and YI of the obtained resin film within a desired range, a range of 0.85 to 2.0 is preferred, a range of 0.95 to 1.5 is more preferred, and a range of 1.01 to 1.25 is even more preferred. By setting these ranges, heat resistance at high temperatures is improved, decomposition reactions during heating are suppressed, and it is preferable in terms of reducing yellowness (YI value) and haze (Haze value).

[0505] Furthermore, regarding the molar ratio ((moles of X2 + moles of X4) / (moles of X1 + moles of X3) of the tetracarboxylic dianhydride components (X1 and X3) and diamine components (X2 and X4) during the synthesis of the aforementioned polyamic acid-imide copolymer, from the viewpoint of controlling the coefficient of thermal expansion, residual stress, elongation, and YI of the obtained resin film within the desired range, it is preferably set to a range of 0.92 to 1.05, more preferably to a range of 0.94 to 1.00. By setting it to the above range, the molecular weight of the polyamic acid-imide copolymer can be easily increased, the processability of the resin composition is improved, uneven coating during film production can be suppressed, and it is preferred from the viewpoint of reducing haze (YI value). In addition, in the above range, the terminal amines of the polyamic acid-imide copolymer are reduced, the decomposition reaction during heating is suppressed, the thermal stability in the high-temperature region is improved, and the yellowness (YI value) is reduced.

[0506] In the synthesis of polyamic acid-imide copolymers, the molecular weight can be controlled by adjusting the ratio of tetracarboxylic dianhydride to diamine and by adding a capping agent. The closer the ratio of tetracarboxylic dianhydride to diamine is to 1:1 and the less capping agent is used, the greater the molecular weight of the polyimide can be.

[0507] High-purity products are recommended for use as both the tetracarboxylic dianhydride and diamine components. Their purity is preferably 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.5% by mass or more, respectively. When multiple dianhydride or diamine components are used in combination, the above-mentioned purity is sufficient when considering the total purity of the dianhydride or diamine components; it is preferable that all types of dianhydride and diamine components used each have the above-mentioned purity.

[0508] The solvents shown in (d) above as organic solvents can be used as the solvent for the reaction, but are not limited thereto.

[0509] Other components may be the compounds described in (e) imidization catalysts above, but are not limited thereto.

[0510] The solvent used in the synthesis of polyimide preferably has a boiling point of 60°C to 300°C at normal pressure, more preferably 140°C to 280°C, and particularly preferably 170°C to 270°C. When the boiling point of the solvent is higher than 300°C, the drying process requires a longer time. On the other hand, when the boiling point of the solvent is lower than 60°C, the surface of the resin film becomes rough and air bubbles are mixed into the resin film during the drying process, sometimes resulting in a non-uniform film.

[0511] As described above, the preferred solvent has a boiling point of 170°C to 270°C at normal pressure. From the viewpoint of solubility and edge bounce during coating, a solvent with a vapor pressure of 250 Pa or less at 20°C is more preferred. More specifically, one or more solvents selected from the group consisting of N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF) are preferred, and solvents described in item "(d) Organic Solvents" above may be used appropriately. The water content in the solvent is preferably 3000 ppm by mass or less. These solvents can be used alone or in mixtures of two or more.

[0512] [Manufacturing method of polyamic acid]

[0513] The polyamic acid in the fourth embodiment of the present invention is not limited, and for example, it can be manufactured by the method described in International Publication No. 2017 / 051827.

[0514] <Polyimide copolymer>

[0515] As another aspect of this disclosure, a film is provided that is formed from a polyimide copolymer, said polyimide copolymer being formed by imidizing (c) the polyamic acid-imide copolymer contained in the above-described resin composition. More specifically, a polyimide copolymer may be provided, characterized in that it comprises structural units shown in the following general formula (2), and, as X2, has the structure shown in the above general formula (A-1) or the above general formula (A-2).

[0516]

[0517] {In the formula, X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n and m are positive integers}

[0518] From the viewpoint that polyimide films containing polyimide copolymers exhibit excellent transparency, haze, heat resistance, and coefficient of linear expansion, the polyimide copolymers preferably satisfy any of the following:

[0519] • The diamine component constituting X2 in general formula (2) is a compound in which two * are replaced by -NH2 in the structure shown in general formula (A-1) or general formula (A-2);

[0520] • X3 in general formula (2) is selected from at least one of the following groups: the structure shown in the above general formula (A-3), the structure derived from ODPA, and the structure derived from 6FDA;

[0521] • In general formula (2), X1 is selected from at least one of the following groups: structures derived from BPDA, structures derived from ODPA, and structures derived from TAHQ;

[0522] • The molar ratio (X2 / X1) of X2 to X1 contained in general formula (2) is 0.84 to 1.00;

[0523] • The molar ratio of X4 to X3 (X4 / X3) in general formula (2) is 1.01 to 2.00; and

[0524] • The molar ratio (number of moles of structural unit N: number of moles of structural unit M) of polyimide structural units composed of X1 and X2 to polyimide structural units composed of X3 and X4 in general formula (2) is in the range of 60:40 to 95:5;

[0525] • X1 or X3 is selected from at least one of the following groups: the structure shown in the above general formula (A-3), the structure derived from 4,4'-oxophthalic dianhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA);

[0526] X4 is selected from at least one of the groups consisting of the structures shown in the above general formulas (A-4), (A-5) and (A-6).

[0527] From the viewpoint that polyimide films containing polyimide copolymers have excellent transparency, haze, heat resistance, and coefficient of linear expansion, it is preferable that the following components 1 and 2 are not included when X2 in the general formula (2) of the polyimide copolymer is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate:

[0528] When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), X4 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and

[0529] The 2.X3 group is derived from norcamphene-2-spiro-α-cyclopentanone α-α'-spiro-2”-norcamphene-5,5”,6,6”-tetracarboxylic acid dianhydride.

[0530] From the viewpoints of transparency, heat resistance, low residual stress and bending resistance, the polyimide copolymer is preferably: when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorenidine (BPAF), X4 in general formula (2) does not include groups derived from 4,4'-diaminodiphenyl sulfone or 2,2'-bis(trifluoromethyl)benzidine.

[0531] <Resin compositions containing polyamic acid>

[0532] As another aspect of this disclosure, a resin composition is provided comprising: a polyamic acid containing a structural unit of the following general formula (3), an organic solvent described above (d), and an imidization catalyst (e), characterized in that the imidization catalyst is an imidazole compound containing N-tert-butoxycarbonyl imidazole (N-Boc-imidazole) and / or 1-methylimidazole, or characterized in that the imidization catalyst is an imidazole compound, and the content of the imidization catalyst is 5 parts by mass or more relative to 100 parts by mass of the polyamic acid.

[0533]

[0534] {In the formula, X1 represents a tetravalent organic group, X2 represents a divalent organic group, and n is a positive integer}

[0535] In the resin composition comprising the structural unit shown in general formula (3), N-tert-butoxycarbonyl imidazole (N-Boc-imidazole) and 1-methylimidazole are preferably included as the (e) imidization catalyst. Furthermore, the content of the (e) imidization catalyst is preferably in the range of 0.02 to 0.15 moles of repeating units of the polyamic acid having the structural unit shown in general formula (3).

[0536] X1, X2, and n in general formula (3) can be as defined for general formula (1) or (2) above. As X1, it is preferably selected from at least one of the following groups: the structure shown in general formula (A-3), the structure derived from 4,4'-oxophthalic dianhydride (ODPA), the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA), the structure derived from biphenyl tetracarboxylic dianhydride (BPDA), and the structure derived from 4,4'-biphenyl bis(triphenyl phthalic acid monoester anhydride) (TAHQ). As X2, it is preferably selected from at least one of the following groups: the structure shown in general formula (A-1), general formula (A-2), general formula (A-4), general formula (A-5), and general formula (A-6), and more preferably the structure shown in general formula (A-1).

[0537] The weight-average molecular weight (Mw) of polyamic acid is preferably 2,639 or more, more preferably 2,639 to 300,000 or 10,000 to 300,000, even more preferably 20,000 to 250,000, and particularly preferably 40,000 to 200,000. When the weight-average molecular weight is 2,639 or more, the mechanical properties such as elongation and tensile strength are excellent, the residual stress is low, and the YI is reduced. When the weight-average molecular weight is 300,000 or less, the viscosity and concentration of the varnish containing polyamic acid are well balanced, the processability is good, and the film unevenness during coating is reduced. In addition, when the Mw of polyamic acid is 170,000 or more, it tends to have excellent transparency, haze, heat resistance and coefficient of linear expansion. Therefore, a Mw of 220,000 or more is preferred, and this tendency is more pronounced when the structure shown in the above general formula (A-1) is X2 in general formula (3). In this disclosure, the weight-average molecular weight is a value obtained using gel permeation chromatography (hereinafter also referred to as GPC) in the form of a standard polystyrene equivalent.

[0538] <Polyimide>

[0539] As another aspect of this disclosure, a polyimide comprising a structural unit M as shown in general formula (3) below, or a polyimide having a structure as shown in general formula (16) below, is provided.

[0540]

[0541] {In the formula, X3 represents a tetravalent organic group, X4 represents a divalent organic group, and m is a positive integer}

[0542]

[0543] {In the formula, P1 and P2 are the same as P1 and P2 in general formula (I) or (II), and m is a positive integer.}

[0544] The polyimide is characterized in that X3 in general formula (3) comprises at least one of the following: a structure selected from the structure shown in the above-described general formula (A-3), a structure derived from 4,4'-oxophthalic dianhydride (ODPA), and a structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA).

[0545] X4 in general formula (3) is as described as X4 in general formula (1) or (2) above. From the same point of view as X4 in general formula (1) or (2) above, the diamine component constituting X4 in general formula (3) is preferably different from any of the diamine composition or types, more preferably an aromatic diamine composition or type, and even more preferably X4 in general formula (3) is at least one of the group consisting of the structures shown in general formula (A-4), general formula (A-5) and general formula (A-6) described above.

[0546] The preferred P1 and P2 in formula (I) or (II) are also preferred in polyimides of formula (16) for the same reason. The number of repeating units m in formula (16) is not particularly limited and can be an integer from 2 to 150.

[0547] It should be noted that the polyimide obtained from the resin composition preferably does not contain substantially any aprotic polar substances with a boiling point of 250°C to 350°C contained in the resin composition, and may contain less than 1000 ppm.

[0548] Methods for manufacturing resin compositions

[0549] The method for manufacturing the resin composition described above is not particularly limited, and may be based on, for example, the following methods.

[0550] <Purification of Silicon-Containing Compounds>

[0551] The resin composition can be manufactured by subjecting a polycondensation reaction of a polycondensation component comprising an acid dianhydride, a diamine, and a silicon-containing compound. As a method to reduce the total amount of cyclic silicon-containing compounds in the resin composition, examples include purifying the silicon-containing compound before the polycondensation reaction to reduce the total amount of cyclic silicon-containing compounds. Alternatively, the resin composition can be purified after the polycondensation reaction to reduce the total amount of cyclic silicon-containing compounds.

[0552] One method for purifying silicon-containing compounds includes, for example, stripping the compound by blowing an inert gas, such as nitrogen, into it in any container. The stripping temperature is preferably 200°C or higher and 300°C or lower, more preferably 220°C or higher and 300°C or lower, and even more preferably 240°C or higher and 300°C or lower. The lower the vapor pressure, the more preferred; preferably 1000 Pa or lower, more preferably 300 Pa or lower, even more preferably 200 Pa or lower, and even more preferably 133.32 Pa (1 mmHg). Pa The stripping time is preferably 4 hours or more and 12 hours or less, more preferably 6 hours or more and 10 hours or less. By adjusting to the above conditions, monocyclic silicon-containing compounds can be effectively removed, and the total amount of cyclic silicon-containing compounds can be controlled within a preferred range.

[0553] <Synthesis of Polyimide / Polyimide Precursors>

[0554] Polyimide precursors can be synthesized by subjecting a polycondensation reaction of a polycondensation component comprising an acid dianhydride, a diamine, and a silicon-containing compound. Regarding the synthesis of polyimide / polyimide precursors, a method for manufacturing a resin composition, for example including any of the following steps, is provided.

[0555] • A process of providing a polyimide precursor and / or polyimide by performing a polycondensation reaction on at least one compound selected from the above-mentioned diamine compounds, at least one compound selected from the above-mentioned acid dianhydride compounds, and other compounds;

[0556] • A process of providing a polyimide precursor and / or polyimide by performing a polycondensation reaction on at least one compound selected from the above-mentioned diamine compounds, at least one compound selected from the above-mentioned acid dianhydride compounds, a silicon-containing compound represented by general formula (13) and other compounds.

[0557] Furthermore, the silicon-containing compound is preferably the substance obtained through the above purification process. In a preferred embodiment, the polycondensation component is formed from an acid dianhydride, a diamine, and a silicon-containing compound. The polycondensation reaction is preferably carried out in a suitable solvent. Specifically, examples include: after dissolving a specified amount of the diamine component and the silicon-containing compound in a solvent, adding a specified amount of acid dianhydride to the resulting diamine solution and stirring. The imidization during the synthesis of polyimides can be thermal imidization or chemical imidization using an imidization catalyst.

[0558] Regarding the molar ratio of dianhydride to diamine in the synthesis of polyimide / polyimide precursors, from the viewpoint of increasing the molecular weight of the polyimide precursor resin and the slot coating characteristics of the resin composition, the preferred range is dianhydride:diamine = 100:90 to 100:110 (0.90 to 1.10 molar parts of diamine relative to 1 molar part of dianhydride), and more preferably 100:95 to 100:105 (0.95 to 1.05 molar parts of diamine relative to 1 molar part of dianhydride).

[0559] The molecular weight of polyimide / polyimide precursors can be controlled by adjusting the types of acid dianhydride, diamine, and silicon-containing compounds, the molar ratio of acid dianhydride to diamine, the addition of end-capping agents, and the reaction conditions. The closer the molar ratio of acid dianhydride to diamine is to 1:1, and the less end-capping agent is used, the more likely the polyimide precursor will have a higher molecular weight.

[0560] High-purity products are recommended for use as both the dianhydride and diamine components. Preferably, their purity is 98% by mass or more, more preferably 99% by mass or more, and even more preferably 99.5% by mass or more, respectively. High purity can also be achieved by reducing the water content in both the dianhydride and diamine components. When using multiple dianhydride components and / or multiple diamine components, it is preferable that both the dianhydride and diamine components have the above-mentioned purity, and more preferably, all types of dianhydride and diamine components used have the above-mentioned purity.

[0561] The solvent used in the reaction is not particularly limited as long as it can dissolve the acid dianhydride and diamine components, as well as the generated polyimide / polyimide precursor, and can yield a high molecular weight polymer. Examples of such solvents include aprotic solvents, phenolic solvents, ether and glycol solvents, etc.

[0562] Examples of nonprotic solvents include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N-methylcaprolactam, 1,3-dimethylimidazolinone, tetramethylurea, and amide solvents of the following general formulas; lactone solvents such as γ-butyrolactone and γ-valerolactone; phosphorus-containing amide solvents such as hexamethylphosphoramide and hexamethylphosphinetriamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as cyclohexanone and methylcyclohexanone; tertiary amine solvents such as methylpyridine and pyridine; and ester solvents such as (2-methoxy-1-methylethyl) acetate.

[0563]

[0564] In the formula, R 12 =Methyl Equamid M100 (trade name: KJ CHEMICALS) and R 12 =Equamid B100 (product name: KJ CHEMICALS) as shown in the figure.

[0565] Examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol.

[0566] Examples of ether and glycol solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane.

[0567] These solvents can be used alone or in combination of two or more.

[0568] The solvent used in the synthesis of polyimide / polyimide precursor preferably has a boiling point of 60–300°C, more preferably 140–280°C, and even more preferably 170–270°C at atmospheric pressure. By making the boiling point of the solvent less than 300°C, the drying process is shortened. If the boiling point of the solvent is 60°C or higher, roughness of the resin film surface and the incorporation of air bubbles into the resin film are less likely to occur during the drying process, resulting in a more uniform film. In particular, from the viewpoint of solubility and reducing edge abnormalities during coating, it is preferable to use a solvent with a boiling point of 170–270°C and / or a vapor pressure of 250 Pa or less at 20°C. More specifically, it is preferable to select one or more from the group consisting of N-methyl-2-pyrrolidone (NMP), γ-butyrolactone (GBL), and compounds represented by the above general formula (6).

[0569] For optimal polycondensation reaction, the water content in the solvent is preferably 3,000 ppm by mass or less. The content of molecules with a molecular weight less than 1,000 in the resin composition is preferably less than 5% by mass. The presence of molecules with a molecular weight less than 1,000 in the resin composition is considered to be related to the water content of the solvent and raw materials (acid dianhydride, diamine) used in the synthesis. Specifically, this can be attributed to the fact that some of the acid dianhydride monomers undergo hydrolysis due to water content in the anhydride group, forming carboxyl groups, and thus do not increase in molecular weight, but remain in a low-molecular-weight state. Therefore, the lower the water content of the solvent used in the above-mentioned polycondensation reaction, the better. The water content of the solvent is preferably 3,000 ppm by mass or less, more preferably 1,000 ppm by mass or less. Similarly, the water content in the raw materials is also preferably 3,000 ppm by mass or less, more preferably 1,000 ppm by mass or less.

[0570] It can be considered that the water content of the solvent is related to the solvent grade used (dehydration grade, general grade, etc.), solvent container (bottle, 18L tank, small can, etc.), solvent storage conditions (whether it is sealed with rare gas, etc.), and the time from opening to use (whether it is used immediately after opening or after a certain period of time, etc.). It can also be considered related to the rare gas replacement of the reactor before synthesis and whether rare gas is circulated during synthesis. Therefore, it is recommended that when synthesizing polyimide precursors, high-purity products be used as raw materials, solvents with low water content be used, and measures be taken to prevent moisture from the environment from being introduced into the system before and during the reaction.

[0571] When dissolving the various polycondensation components in the solvent, heating may be performed as needed. From the viewpoint of obtaining a polyimide precursor with a high degree of polymerization, the reaction temperature for synthesizing the polyimide precursor is preferably 0°C to 120°C, 40°C to 100°C, or 60°C to 100°C, and the polymerization time is preferably 1 to 100 hours or 2 to 10 hours. By setting the polymerization time to 1 hour or more, a polyimide precursor with a uniform degree of polymerization is formed; by setting it to 100 hours or less, a polyimide precursor with a high degree of polymerization can be obtained.

[0572] In addition to the polyimide / polyimide precursor described above, the resin composition may contain other additional polyimide precursors. However, from the viewpoint of reducing the oxygen dependence of the YI value and total light transmittance of the polyimide film, the mass percentage of the additional polyimide / polyimide precursor relative to the total amount of polyimide / polyimide precursor in the resin composition is preferably 30% by mass or less, and more preferably 10% by mass or less.

[0573] A portion of the polyimide precursor may be imidized (partially imidized). Partial imidization of the polyimide precursor improves the viscosity stability during storage of the resin composition. From the viewpoint of achieving a balance between the solubility of the polyimide precursor in the resin composition and the storage stability of the solution, the imidization rate is preferably 5% or more, more preferably 8% or more, and preferably 80% or less, more preferably 70% or less, and even more preferably 50% or less. This partial imidization is achieved by heating the polyimide precursor and dehydrating and ring-closing it. This heating can be performed at a temperature preferably 120–200°C, more preferably 150–185°C, and even more preferably 150–180°C, preferably for 15 minutes to 20 hours, and more preferably for 30 minutes to 10 hours.

[0574] As a polyimide precursor, a substance can be obtained by adding N,N-dimethylformamide dimethyl acetal or N,N-dimethylformamide diethyl acetal to a polyimide / polyimide precursor obtained by the above reaction and heating it to esterify part or all of the carboxylic acid. Esterification can improve viscosity stability during storage. These ester-modified polyamic acids can also be obtained by reacting the above-mentioned dianhydride component sequentially with a monohydric alcohol in an equivalent amount relative to the dianhydride group, and a dehydrating condensing agent such as thionyl chloride or dicyclohexylcarbodiimide, followed by a condensation reaction with a diamine component.

[0575] Synthesis of Polyimide

[0576] As a more preferred method, polyimide varnish can be manufactured by dissolving the acid dianhydride component and the diamine component in a solvent, such as an organic solvent, adding an azeotropic solvent such as toluene, and removing the water generated during imidization from the system, thereby producing a polyimide solution containing polyimide and solvent (also called polyimide varnish). Here, the reaction conditions are not particularly limited; for example, the reaction temperature is 0°C to 180°C, and the reaction time is 3 to 72 hours. To ensure sufficient reaction with the sulfonated diamine, a heating reaction at 180°C for approximately 12 hours is preferred. Furthermore, an inert atmosphere such as argon or nitrogen is preferred during the reaction.

[0577] <Preparation of Resin Compositions>

[0578] When the solvent used in synthesizing the polyimide precursor is the same as the solvent contained in the resin composition, the synthesized polyimide / polyimide precursor solution can be directly used as the resin composition. Alternatively, the resin composition can be prepared by adding one or more of a further solvent and additional components to the polyimide precursor at a temperature range of room temperature (25°C) to 80°C, followed by stirring and mixing. This stirring and mixing can be performed using suitable equipment such as a Three One Motor (manufactured by Shin-To Chemical Co., Ltd.) equipped with stirring blades, or a rotary stirrer. The resin composition can be heated to 40°C to 100°C as needed.

[0579] On the other hand, if the solvent used in the synthesis of the polyimide / polyimide precursor is different from the solvent contained in the resin composition, the polyimide / polyimide precursor can be separated by removing the solvent from the synthesized polyimide precursor solution through appropriate methods such as reprecipitation or solvent distillation. Then, by adding the desired solvent and any additional components as needed to the separated polyimide precursor at a temperature range of room temperature (25°C) to 80°C, and by stirring and mixing, a resin composition can also be prepared.

[0580] In particular, during the preparation of the resin composition, it is especially preferable to add an aprotic polar substance with a boiling point of 250°C to 350°C as a final step after the synthesis of the polyimide / polyimide precursor. This improves the in-plane uniformity of the thickness of the resulting polyimide resin film and reduces its yellowness (YI value).

[0581] After preparing the resin composition as described above, a portion of the polyimide precursor can be dehydrated and imidized (partially imidized) to the extent that polymer precipitation does not occur by heating the resin composition at, for example, 130–200°C for, for example, 5 minutes to 2 hours. By controlling the heating temperature and heating time, the imidization rate can be controlled. Partial imidization of the polyimide precursor can improve the viscosity stability of the resin composition during storage.

[0582] From the viewpoint of slit coating performance, the solution viscosity of the resin composition is preferably 500–100,000 mPa·s, more preferably 1,000–50,000 mPa·s, and even more preferably 3,000–20,000 mPa·s. Specifically, from the viewpoint of minimizing leakage from the slit nozzle, a viscosity of 500 mPa·s or higher is preferred, more preferably 1,000 mPa·s or higher, and even more preferably 3,000 mPa·s or higher. From the viewpoint of minimizing clogging of the slit nozzle, a viscosity of 100,000 mPa·s or lower is preferred, more preferably 50,000 mPa·s or lower, and even more preferably 20,000 mPa·s or lower.

[0583] Regarding the solution viscosity of the resin composition used in the synthesis of polyimide / polyimide precursors, if it exceeds 200,000 mPa·s, it may cause problems with stirring during synthesis. However, even if the solution reaches a high viscosity during synthesis, a resin composition with good handleability can be obtained by adding solvent and stirring after the reaction is complete. The solution viscosity of the resin composition is the value measured using an E-type viscometer (e.g., VISCONICEHD, manufactured by Toki Sangyo Co., Ltd.) at 23°C.

[0584] From the viewpoint of viscosity stability when storing the resin composition, the water content of the resin composition is preferably 3,000 ppm by mass or less, more preferably 2,500 ppm by mass or less, even more preferably 2,000 ppm by mass or less, even more preferably 1,500 ppm by mass or less, particularly preferably 1,000 ppm by mass or less, particularly preferably 500 ppm by mass or less, particularly preferably 300 ppm by mass or less, and particularly preferably 100 ppm by mass or less.

[0585] Polyimide Resin Films and Their Manufacturing Methods

[0586] Using the resin composition described above, a polyimide resin film (hereinafter also referred to as a polyimide film) can be provided. The method for manufacturing the polyimide film described above includes the following steps: a coating step of coating a resin composition onto the surface of a support; a film-forming step of heating the resin composition to form a polyimide resin film; and a peeling step of peeling the polyimide resin film off the support.

[0587] Coating process

[0588] In the coating process, a resin composition is coated onto the surface of the support. The support is not particularly limited as long as it is heat-resistant to the heating temperature in the subsequent film-forming process (heating process) and has good peelability in the peeling process. Examples of supports include, for instance, glass substrates, such as alkali-free glass substrates; silicon wafers; resin substrates such as PET (polyethylene terephthalate), OPP (extended polypropylene), polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyamide-imide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylene sulfone, and polyphenylene sulfide; and metal substrates such as stainless steel, alumina, copper, and nickel.

[0589] When forming a thin-film polyimide molded body, a glass substrate or silicon wafer is preferred. When forming a thick-film or sheet-like polyimide molded body, a support formed of PET (polyethylene terephthalate) or OPP (extended polypropylene) is preferred.

[0590] Coating methods typically include blade coaters, air knife coaters, roller coaters, spin coaters, flow coaters, die coaters, and bar coaters; spin coating, spray coating, and dip coating; and printing technologies such as screen printing and gravure printing. The resin composition is preferably coated using slot coating. The coating thickness should be appropriately adjusted based on the desired thickness of the resin film and the content of the polyimide precursor in the resin composition, preferably around 1 to 1,000 μm. The temperature during the coating process can be room temperature; however, to reduce viscosity and improve workability, the resin composition can be heated to, for example, 40°C to 80°C.

[0591] <Optional drying process>

[0592] The drying process can be performed immediately after the coating process, or the drying process can be omitted and proceed directly to the subsequent film-forming process (heating process). The drying process is performed to remove organic solvents from the resin composition. When performing the drying process, suitable equipment such as heating plates, box dryers, or conveyor belt dryers can be used. The temperature of the drying process is preferably 80°C to 200°C, more preferably 100°C to 150°C. The duration of the drying process is preferably 1 minute to 10 hours, more preferably 3 minutes to 1 hour. By operating as described above, a coating film containing the polyimide precursor is formed on the support.

[0593] <Film Forming Process>

[0594] Next, a film-forming process (heating process) is performed. The heating process involves removing the organic solvents contained in the coating and performing an imidization reaction of the polyimide precursor in the coating to obtain a polyimide resin film. This heating process can be performed using equipment such as an inert gas oven, a heating plate, a box dryer, or a belt dryer. This process can be performed simultaneously with the drying process, or the two processes can be performed sequentially.

[0595] The heating process can be performed in an air atmosphere, but from the viewpoint of obtaining safety and good transparency, low thickness retardation (Rth), and low YI value of the resulting polyimide film, it is preferable to perform it in an inert gas atmosphere. Examples of inert gases include nitrogen and argon. The heating temperature can be appropriately set according to the type of polyimide precursor and the type of solvent in the resin composition, preferably 250°C to 550°C, more preferably 300°C to 450°C. If the temperature is above 250°C, imidization is well performed, and if the temperature is below 550°C, adverse conditions such as reduced transparency and deterioration of heat resistance of the resulting polyimide film can be avoided. The heating time is preferably about 0.1 hours to 10 hours.

[0596] In particular, when the resin composition contains aprotic polar substances with a boiling point of 250°C to 350°C, these substances will remain in the film even at temperatures above 250°C during the polyimide heating process, acting as plasticizers at high temperatures. Therefore, the resin remains soft and fluid, resulting in improved in-plane uniformity of the polyimide resin film thickness and reduced YI.

[0597] In this embodiment, from the viewpoint of the transparency and YI value of the obtained polyimide film, the oxygen concentration of the surrounding atmosphere in the above-mentioned heating process is preferably 2,000 ppm by mass or less, more preferably 100 ppm by mass or less, and even more preferably 10 ppm by mass or less. By heating in an atmosphere with an oxygen concentration of 2,000 ppm by mass or less, the YI value of the obtained polyimide film can be set to 30 or less.

[0598] <Stripping Process>

[0599] In the peeling process, the polyimide resin film on the support is cooled to, for example, room temperature (25°C) to about 50°C before peeling. Examples of this peeling process include (1) to (4) below.

[0600] (1) After fabricating a structure containing a polyimide resin film / support by the above method, a laser is irradiated from the support side of the structure to abrade the interface between the support and the polyimide resin film, thereby peeling off the polyimide resin. Examples of laser types include solid-state (YAG) lasers and gas (UV excimer) lasers. A wavelength of 308 nm or similar is preferred (see Japanese Patent Publication No. 2007-512568, Japanese Patent Publication No. 2012-511173, etc.).

[0601] (2) A method for forming a release layer on a support before coating a resin composition onto a support, thereby obtaining a composition comprising a polyimide resin film / release layer / support, and then peeling off the polyimide resin film. Examples of release layers include PARYLENE (registered trademark, manufactured by PARYLENE Co., Ltd., Japan) and tungsten oxide. Release agents such as vegetable oil-based, silicone-based, fluorine-based, and alkyd-based release agents can also be used (see Japanese Patent Application Publication No. 2010-067957, Japanese Patent Application Publication No. 2013-179306, etc.).

[0602] Laser irradiation using method (2) and method (1) can also be used in combination.

[0603] (3) A method for obtaining a polyimide resin film by etching a metal substrate that can be etched as a support, after obtaining a structure containing a polyimide resin film / support, by etching the metal with an etchant. For example, copper (specifically, electrolytic copper foil "DFF" manufactured by Mitsui Metals & Mining Co., Ltd.), aluminum, etc., can be used as the metal. For the etchant, ferric chloride, etc., can be used for copper, and dilute hydrochloric acid, etc., can be used for aluminum.

[0604] (4) After obtaining a constituent body containing a polyimide resin film / support by the above method, an adhesive film is pasted on the surface of the polyimide resin film, the adhesive film / polyimide resin film is separated from the support, and then the polyimide resin film is separated from the adhesive film.

[0605] Among these peeling methods, from the viewpoint of the difference in refractive index, YI value, and elongation of the resulting polyimide resin film, method (1) or (2) is preferred. From the viewpoint of the difference in refractive index of the resulting polyimide resin film, method (1), namely, the irradiation process of irradiating the support side with a laser before the peeling process, is more preferred. It should be noted that when copper is used as the support in method (3), a tendency is observed that the YI value of the resulting polyimide resin film increases and the elongation decreases. This can be attributed to the influence of copper ions.

[0606] The thickness of the resulting polyimide film is not limited, but is preferably 1 to 200 μm, more preferably 5 to 100 μm.

[0607] <Polyimide film>

[0608] Another aspect of this disclosure provides a polyimide film, characterized in that, when measured at a film thickness of 10 μm, the tensile modulus at 25°C is 6 GPa or more, the tensile modulus at 350°C is 0.5 GPa or more, and the yellowness (YI value) is 12 or less.

[0609] The polyimide film is preferably prepared using the polyamic acid-imide copolymer and / or polyimide copolymer described above as raw materials. From the viewpoint of obtaining a balance between transparency, heat resistance, and coefficient of linear expansion, the haze value of the polyimide film is preferably less than 0.5%, and / or, from the viewpoint of obtaining a balance between haze value, heat resistance, and coefficient of linear expansion, the rate of change of yellowness (YI value) of the polyimide film after being held at 430°C for 1 hour is preferably less than 20%.

[0610] Resin films manufactured using the polyamic acid-imide copolymer, polyamic acid, polyimide, and resin composition described above can be used not only as semiconductor insulating films, TFT-LCD insulating films, and electrode protective films, but also as substrates, particularly suitable for use in the manufacture of flexible devices. Examples of flexible devices that can utilize resin films and laminates include flexible displays, flexible solar cells, flexible touch panel electrode substrates, flexible lighting, and flexible batteries.

[0611] Applications of Polyimide Films

[0612] The polyimide film obtained from the resin composition described above can be used as, for example, a semiconductor insulating film, a thin-film transistor liquid crystal display (TFT-LCD) insulating film, an electrode protective film, and can also be used as a transparent substrate for display devices such as liquid crystal displays, organic electroluminescent displays, field emission displays, and electronic paper.

[0613] In particular, polyimide films can be suitably used as flexible substrates for thin-film transistor (TFT) substrates, color filter substrates, touch panel substrates, and transparent conductive films (ITO, Indium Thin Oxide) in the manufacture of flexible devices. Examples of flexible devices that can use polyimide films include TFT devices for flexible displays, flexible solar cells, flexible touch panels, flexible lighting, flexible batteries, flexible printed circuit boards, flexible color filters, and surface-covered lenses for smartphones.

[0614] Typically, the process of forming TFTs on a flexible substrate using a polyimide film is carried out at temperatures ranging from 150°C to 650°C. Specifically, in the case of fabricating TFT devices using amorphous silicon, a process temperature of 250°C to 350°C is usually required, and the polyimide film needs to be able to withstand this temperature. Therefore, it is necessary to appropriately select a polymer structure with a glass transition temperature and thermal decomposition start temperature above the process temperature.

[0615] When fabricating TFT devices using metal oxide semiconductors (IGZO, etc.), a process temperature of 320°C to 400°C is typically required. The polyimide film needs to be able to withstand this temperature. Therefore, it is necessary to appropriately select a polymer structure with a glass transition temperature and thermal decomposition start temperature that are above the highest temperature of the TFT fabrication process.

[0616] In the fabrication of TFT devices using low-temperature polycrystalline silicon (LTPS), a process temperature of 380°C to 520°C is typically required. The polyimide film must be able to withstand this temperature; therefore, it is necessary to appropriately select a glass transition temperature and thermal decomposition initiation temperature above the highest temperature in the TFT fabrication process. On the other hand, due to these thermal processes, there is a tendency for the optical properties of the polyimide film (especially light transmittance, retardation characteristics, and YI value) to decrease the higher the temperature of the process. However, polyimides derived from polyimide precursors retain good optical properties even after undergoing thermal processes.

[0617] The following describes a method for manufacturing displays and laminates, using polyimide films as examples of applications.

[0618] <Manufacturing Method of Display>

[0619] In one aspect of this disclosure, the method for manufacturing a display includes the following steps: a coating step of coating a resin composition onto the surface of a support; a film-forming step of heating the resin composition to form a polyimide film (polyimide resin film); an element-forming step of forming elements on the polyimide film; and a peeling step of peeling the polyimide film with the formed elements from the support.

[0620] Manufacturing examples of flexible organic EL displays

[0621] Figure 1 This is a schematic diagram illustrating the structure of a top-emitting flexible organic EL display, an example of a display as one embodiment of this disclosure, located above the polyimide substrate. (For...) Figure 1The organic EL structure 25 will be described below. For example, organic EL elements 250a (emitting red light), 250b (emitting green light), and 250c (emitting blue light) are arranged in a matrix as one unit, and the light-emitting area of ​​each organic EL element is divided by partition walls (dams) 251. Each organic EL element is composed of a lower electrode (anode) 252, a hole transport layer 253, a light-emitting layer 254, and an upper electrode (cathode) 255. On the lower layer 2a, which represents a CVD multilayer film (multilayer barrier layer) formed of silicon nitride (SiN) and silicon oxide (SiO), a plurality of TFTs 256 (selected from low-temperature polycrystalline silicon (LTPS), metal oxide semiconductor (IGZO, etc.)) for driving the organic EL elements, an interlayer insulating film 258 with contact holes 257, and a lower electrode 259 are provided. The organic EL elements are sealed by a sealing substrate 2b, and a hollow portion 261 is formed between each organic EL element and the sealing substrate 2b.

[0622] The manufacturing process of flexible organic EL displays includes: fabricating a polyimide film on a glass substrate support, and fabricating a... Figure 1 The process described includes: the process of manufacturing the organic EL substrate; the process of manufacturing the sealing substrate; the assembly process of bonding the two substrates together; and the peeling process of peeling the organic EL display fabricated on the polyimide film from the glass substrate support. The organic EL substrate manufacturing process, the sealing substrate manufacturing process, and the assembly process can utilize known manufacturing processes. One example is given below, but it is not a limitation. The peeling process is the same as the polyimide film peeling process described above.

[0623] For example, if referring to Figure 1 First, a polyimide film is fabricated on a glass substrate support using the method described above. Then, a multilayer barrier layer composed of silicon nitride (SiN) and silicon oxide (SiO) is fabricated on top of the film using CVD and sputtering methods. Figure 1 In the lower substrate 2a), a metal wiring layer for driving TFTs is fabricated on its upper surface using a photoresist or similar agent. An active buffer layer such as SiO is fabricated on its upper surface using CVD, and a TFT device such as metal-oxide-semiconductor (IGZO) or low-temperature polycrystalline silicon (LTPS) is fabricated on its upper surface. Figure 1 (TFT 256 in the example). After fabricating the TFT substrate for a flexible display, an interlayer insulating film 258 with contact holes 257 is formed using a photosensitive acrylic resin or the like. An ITO film is formed using a sputtering method or the like, and a lower electrode 259 is formed in a manner that pairs with the TFT.

[0624] Next, after forming a separator (dam) 251 using photosensitive polyimide or the like, a hole transport layer 253 and a light-emitting layer 254 are formed within each space defined by the separator. An upper electrode (cathode) 255 is then formed to cover the light-emitting layer 254 and the separator (dam) 251. Subsequently, using a fine metal mask or the like as a mask, an organic EL material emitting red light (and...) is deposited using a known method. Figure 1 The organic EL element 250a that emits red light corresponds to the organic EL element that emits green light (and the organic EL material that emits green light). Figure 1 The organic EL element 250b that emits green light corresponds to the organic EL element that emits blue light (and the organic EL material that emits blue light). Figure 1 (corresponding to the blue-light-emitting organic EL element 250c), thereby fabricating an organic EL substrate. This is achieved by utilizing sealing films, etc. Figure 1 The organic EL substrate is sealed with a sealing substrate 2b), and the device positioned above the polyimide substrate is peeled off from the glass substrate support using a known peeling method such as laser peeling, thereby enabling the fabrication of a top-emitting flexible organic EL display. When using polyimide according to one aspect of this disclosure, a see-through flexible organic EL display can be fabricated. Bottom-emitting flexible organic EL displays can also be fabricated using known methods.

[0625] A flexible liquid crystal display can be manufactured using a polyimide film according to one aspect of this disclosure. Specifically, a polyimide film is fabricated on a glass substrate support using the method described above, and a TFT substrate formed from, for example, amorphous silicon, metal oxide semiconductor (IGZO, etc.), or low-temperature polycrystalline silicon is fabricated using the same method. Separately, according to a coating and film-forming process according to one aspect of this disclosure, a polyimide film is fabricated on a glass substrate support, and a color filter glass substrate (CF substrate) having the polyimide film is fabricated using a known method and a color photoresist, etc. On one of the TFT substrate and the CF substrate, a sealing material including thermosetting epoxy resin is screen-printed into a frame-like pattern representing a partial defect in the liquid crystal injection port. On the other substrate, maintaining a diameter equivalent to the thickness of the liquid crystal layer, spherical spacers formed of plastic or silicon dioxide are distributed.

[0626] Next, the TFT substrate and the CF substrate are bonded together, and the sealing material is cured. Then, liquid crystal material is injected into the space surrounded by the TFT substrate, the CF substrate, and the sealing material using a decompression method. A thermosetting resin is applied to the liquid crystal injection port, and the liquid crystal material is sealed by heating, thereby forming a liquid crystal layer. Finally, the glass substrates on the CF side and the TFT side are peeled off at the interface between the polyimide film and the glass substrate using methods such as laser lift-off, thereby enabling the fabrication of a flexible liquid crystal display.

[0627] <Method for manufacturing laminates>

[0628] One method of manufacturing a laminate according to the present disclosure includes the following steps: a coating step of coating a resin composition onto the surface of a support; a film-forming step of heating the resin composition to form a polyimide film (polyimide resin film); and an element-forming step of forming an element on the polyimide film.

[0629] Examples of components in a laminate, exemplified for the manufacture of flexible devices such as flexible displays, can be cited.

[0630] For example, a glass substrate can be used as the support. The preferred specific steps of the coating and film-forming processes are the same as those described in the method for manufacturing the polyimide film. In the element-forming step, the aforementioned element is formed on the polyimide resin film, which serves as a flexible substrate and is formed on the support. Then, optionally in the peeling step, the polyimide resin film with the element formed and the element can be peeled off from the support.

[0631] In addition, one method of manufacturing a flexible device according to the present disclosure includes the step of manufacturing a laminate using the above-described method for manufacturing laminates.

[0632] The embodiments of the present invention have been described above, but the present invention is not limited thereto and may be appropriately modified without departing from the spirit of the invention.

[0633] Example

[0634] The present invention will be described in more detail below based on embodiments, but these are for illustrative purposes only and the scope of the invention is not limited to the following embodiments.

[0635] The various evaluations in the examples and comparative examples are as follows.

[0636] <Determination of weight-average molecular weight and number-average molecular weight>

[0637] Weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by gel permeation chromatography (GPC) under the following conditions.

[0638] As a solvent, N,N-dimethylformamide (manufactured by Fujifilm and Koden Chemical Co., Ltd., for high-performance liquid chromatography) was used. 24.8 mmol / L lithium bromide monohydrate (manufactured by Fujifilm and Koden Chemical Co., Ltd., 99.5% purity) and 63.2 mmol / L phosphoric acid (manufactured by Fujifilm and Koden Chemical Co., Ltd., for high-performance liquid chromatography) were added and dissolved just before the determination. A standard curve for calculating the weight-average molecular weight was prepared using standard polystyrene (Easy Type PS-1, manufactured by Agilent Technologies).

[0639] Device: HLC-8220GPC (manufactured by Tosoh Corporation)

[0640] Columns: 2 TSK gel Super HM-H (manufactured by Tosoh Corporation)

[0641] Flow rate: 0.5 mL / min

[0642] Column temperature: 40℃

[0643] Detector: UV-8220 (UV-VIS: Ultraviolet-Vis Spectrophotometer, manufactured by Tosoh Corporation)

[0644] <Evaluation of Glass Transition Temperature (Tg)>

[0645] For the determination of the glass transition temperature (Tg) in the temperature range of 50–500 °C, polyimide films were cut into 3 mm × 20 mm pieces as test specimens, and thermomechanical analysis was performed. As the measuring apparatus, a Seiko Instruments Inc. (EXSTAR 6000) was used. Tensile measurements of the test specimens in the temperature range of 50–500 °C were performed under the conditions of a tensile load of 49 mN, a heating rate of 10 °C / min, and a nitrogen gas flow (flow rate 100 mL / min). The glass transition temperature of the polyimide film (10 μm thick) was determined from the inflection point of the obtained curve. For those in the 50–500 °C range where no inflection point was observed, the Tg was considered to be above 500 °C, and was sometimes shown in the table below in the form of "-".

[0646] <Evaluation of Residual Stress>

[0647] On a 6-inch silicon wafer with a pre-determined warpage thickness of 625 μm ± 25 μm, various resin compositions were coated using a spin coater and pre-baked at 100°C for 7 minutes. Subsequently, the oxygen concentration in the chamber was adjusted to be below 10 ppm by mass, and a heat curing process (curing process) was performed at 430°C for 1 hour to produce a silicon wafer with a cured polyimide resin film of 10 μm thickness.

[0648] The warpage of the wafer was measured using a residual stress measuring device (Tencor, model name: FLX-230) to evaluate the residual stress generated between the silicon wafer and the resin film.

[0649] S: Residual stress exceeds -5 MPa but is below 15 MPa (residual stress is rated as "excellent").

[0650] A: Residual stress exceeding 15 MPa but below 25 MPa (residual stress evaluation is "good")

[0651] B: Residual stress exceeds 25 MPa (residual stress is rated as "poor").

[0652] <Evaluation of Yellowness (YI value) and Haze (Haze value)>

[0653] On a 100 mm square (0.7 mm thick) EAGLE XG glass substrate, various resin compositions were applied using a spin coater and pre-baked at 80°C for 30 minutes. Then, the oxygen concentration in the substrate was adjusted to below 10 ppm by mass, and a heat curing treatment was performed at 430°C for 1 hour to produce a glass substrate with a 10 μm thick polyimide resin film after curing. For the obtained polyimide-coated glass substrate, the yellowness (YI value) was measured using a Spectotometer (SE6000) manufactured by Nippon Denshoku Kogyo Co., Ltd. with a D65 light source, and the haze (Haze value) was measured using a Konica Minolta Spectrophotometer (CM-3600A) manufactured by Konica Minolta Co., Ltd. with a D65 light source.

[0654] S: YI value is 8 or higher and below 12 (YI value is rated as "S").

[0655] A: YI value is 12 or higher but below 15 (YI value is rated "A").

[0656] B: YI value is 15 or above (YI value is rated "B").

[0657] S: Haze value below 0.2% (Haze value is rated "S")

[0658] A: Haze score between 0.2% and 0.5% (Haze score is rated "A")

[0659] B: Haze score exceeds 0.5% (Haze score is rated "B")

[0660] <Evaluation of bending resistance>

[0661] On a 6-inch silicon wafer pre-sputtered with approximately 100 nm of aluminum (Al) to a thickness of 625 μm ± 25 μm, various resin compositions were coated using a spin coater and pre-baked at 100°C for 7 minutes. Subsequently, the oxygen concentration in the chamber was adjusted to below 10 ppm by mass, and a heat curing treatment was performed at 430°C for 1 hour (curing treatment) to produce a silicon wafer with an Al sputtered film and a cured polyimide resin film with a thickness of 10 μm. The prepared sample was immersed in a 10% hydrochloric acid aqueous solution for 1 day, and the polyimide resin film was peeled off from the silicon wafer. The peeled polyimide film was cut into 15 mm × 100 mm pieces as test pieces.

[0662] Using an MIT-type repetitive bending testing machine (MIT-DA, Toyo Seiki), 100,000 repetitive bending tests were conducted on the prepared test pieces under the conditions of a 250g load, a bending radius (R) of 2mm, a bending angle of 135°, and a speed of 90 cycles / minute. After the test, the samples were removed from the device. Those without scratches were recorded as A, and those with scratches were recorded as B.

[0663] <Evaluation of preservation stability>

[0664] The resin composition was stored at 23°C for 1 week. After that, glass substrates with polyimide resin films were made using the same evaluation method as <Yellowness (YI value) and Haze (Haze value)>. Those with a haze (Haze value) of less than 0.5% were designated as "A", and those with a haze (Haze value) of more than 0.5% were designated as "B".

[0665] <Evaluation of Elastic Modulus>

[0666] In the determination of elastic modulus, polyimide films were cut into 3mm × 20mm pieces as test specimens and subjected to thermomechanical analysis. A Seiko Instruments Inc. (EXSTAR6000) instrument was used as the measuring apparatus. Under a nitrogen atmosphere and with the set temperature fixed at 25°C or 350°C, an initial tensile load of 20mN was applied, with the load varying at a rate of 100mN / min, up to a maximum of 1200mN, and the elongation was measured. The elastic modulus of the polyimide film (10μm thick) was determined from the slope of the resulting curve. Films that were brittle and broke during the test, or those with low Tg and broke midway, were marked "B" in Table 4. The evaluation criteria are as follows.

[0667] Elastic modulus at 25℃

[0668] S: Elastic modulus is above 6 GPa (Evaluation of elastic modulus "S")

[0669] B: YI value below 6 GPa (Evaluation of elastic modulus "B")

[0670] Elastic modulus at 350℃

[0671] S: Elastic modulus is above 0.5 GPa (Evaluation of elastic modulus "S")

[0672] B: YI value below 0.5 GPa (Evaluation of elastic modulus "B")

[0673] <Sputtering Reheating Test>

[0674] An aluminum (Al) film of approximately 100 nm is sputtered onto a glass substrate with a polyimide resin film, prepared using the same method as described above for the evaluation of yellowness (YI value) and haze (Haze value). The Al film is formed on the polyimide film.

[0675] The prepared samples were adjusted to have an oxygen concentration in the chamber below 10 ppm by mass, and then subjected to a heat treatment at 430°C for 1 hour to obtain a glass substrate with a polyimide resin film of 10 μm thickness. For the resulting Al-sputtered glass substrates with polyimide, those without visual expansion or cracking were rated "S", and those with cracking or expansion were rated "B".

[0676] <Evaluation of the 430℃ reheat test>

[0677] The evaluation was conducted using a glass substrate and device with a polyimide resin film, which were prepared using the same method as described above for the evaluation of yellowness (YI value) and haze (Haze value).

[0678] The YI value (YI(A)) of a glass substrate with polyimide obtained by heat curing at 430°C was measured using a Spectotometer (SE6000) manufactured by Nippon Denshoku Kogyo Co., Ltd. with a D65 light source. The substrate was then adjusted to have an oxygen concentration of less than 10 ppm by mass and subjected to a heat treatment at 430°C for 1 hour to obtain a glass substrate with a polyimide resin film with a thickness of 10 μm.

[0679] For the obtained polyimide-coated glass substrate, the YI value (YI(B)) was measured again using a D65 light source on a Nippon Denshoku Kogyo Co., Ltd. spectrophotometer (SE6000) to evaluate the rate of change of the YI value relative to that before heating. The YI value (rate of change) was calculated by the following formula.

[0680] Rate of change of YI value: ((YI(B)-YI(A)) / YI(A)×100(%))

[0681] S: The rate of change of the YI value is greater than 0% and less than 10% (the evaluation of the YI value (rate of change) is "S").

[0682] A: The rate of change of the YI value is greater than 10% but less than 20% (the evaluation of the YI value (rate of change) is "A").

[0683] B: The rate of change of the YI value exceeds 20% (the evaluation of the YI value (rate of change) is "B").

[0684] <IR Curing Defect Evaluation>

[0685] This evaluation assesses the number of defects on the surface of the polyimide film when the resin composition is continuously subjected to IR (infrared) heating and curing (curing) under the assumption of mass production.

[0686] On an alkali-free glass substrate (hereinafter referred to as "glass substrate" or simply "substrate") measuring 100 mm in length, 100 mm in width, and 0.5 mm in thickness, the resin compositions of the examples and comparative examples were coated with a cured film thickness of 10 μm in an inner region 5 mm from the end of the glass substrate. Coating was performed using a slit coater (LC-R300G, manufactured by SCREEN Finetech Solutions Co., Ltd.). The resulting coated glass substrates were then dried using a vacuum dryer (manufactured by Tokyo Ohka Kogyo) at 80°C, 100 Pa, for 30 minutes to remove the solvent, yielding coated film samples.

[0687] Subsequently, using an AMK-1707 IR curing oven (light source: ceramic heater, oven volume 50L, manufactured by AMK), 10 coated film samples of the same resin composition were prepared and heated at 120°C for 10 minutes in a nitrogen atmosphere, followed by a temperature increase of 10°C / min to 430°C for 60 minutes. This was considered one batch, and five batches of the same resin composition were heat-treated (10 pieces * 5 batches, for a total of 50 pieces). It should be noted that when treating other compositions, the IR curing oven was preheated at 500°C for at least 5 hours, and the delivery pipes and other piping were cleaned before use. Then, using the fifth polyimide resin film from the top of the fifth batch, the surface defects of the polyimide resin film were evaluated using a defect inspection device (LCF-5505XU, manufactured by TAKANO). The number of defects larger than 10μm was detected. The evaluation was conducted according to the following criteria.

[0688] Fewer than 25 defects: A (Excellent)

[0689] The number of defects is 25 or more but less than 50: B (Excellent)

[0690] The number of defects is more than 50 but less than 100: C (Good)

[0691] The number of defects is more than 100 but less than 200: D (Acceptable)

[0692] Number of defects 200 or more: E (Defective)

[0693] <Degassing Evaluation>

[0694] When a polyimide resin film is used as the substrate for a TFT, an inorganic film (e.g., SiN) is formed on the obtained polyimide resin film, and the inorganic film is then annealed. Degassing during this annealing process results in a defective sample; therefore, a higher degassing initiation temperature is preferable. This degassing initiation temperature is evaluated using the method described below.

[0695] On an alkali-free glass substrate (hereinafter referred to as "glass substrate" or simply "substrate") measuring 100 mm in length, 100 mm in width, and 0.5 mm in thickness, the resin compositions of the examples and comparative examples were coated with a cured film thickness of 10 μm in an inner region 5 mm from the end of the glass substrate. Coating was performed using a slit coater (LC-R300G, manufactured by SCREEN Finetech Solutions Co., Ltd.). For the resulting coated glass substrate, the solvent was removed using a vacuum dryer (manufactured by Tokyo Ohka Kogyo) at 80°C, 100 Pa, and 30 minutes to obtain coated film samples. Then, five coated film samples of the resin composition were prepared and heated in an IR curing oven AMK-1707 (light source: ceramic heater, oven volume 50L, manufactured by AMK) at 120°C under a nitrogen atmosphere for 10 minutes, followed by a temperature increase of 10°C / min to 430°C for 60 minutes to obtain a polyimide resin film formed on the glass substrate.

[0696] A 100 nm thick SiN film was formed on the obtained polyimide resin film using plasma CVD. The glass substrate with the SiN / polyimide resin film laminate was then heat-treated in an IR curing oven AMK-1707 under the following conditions.

[0697] a. After heating at 120°C for 10 minutes in a nitrogen atmosphere, increase the temperature by 10°C / min and heat at 480°C for 60 minutes.

[0698] b. After heating at 120°C for 10 minutes in a nitrogen atmosphere, increase the temperature by 10°C / min and heat at 470°C for 60 minutes.

[0699] c. After heating at 120°C for 10 minutes in a nitrogen atmosphere, increase the temperature by 10°C / min and heat at 460°C for 60 minutes.

[0700] d. After heating at 120°C for 10 minutes in a nitrogen atmosphere, increase the temperature by 10°C / min and heat at 450°C for 60 minutes.

[0701] e. After heating at 120°C for 10 minutes in a nitrogen atmosphere, increase the temperature by 10°C / min and heat at 440°C for 60 minutes.

[0702] Then, assess whether degassing has occurred using the following benchmarks:

[0703] Under the conditions described in a. above, does the SiN film expand / not expand: A (Excellent)

[0704] Under the conditions described in b. above, the SiN film expands: B (preferably).

[0705] Under the conditions described in c above, the SiN film expands: C (Good)

[0706] Under the conditions described in d. above, the SiN film expands: D (possibly)

[0707] Under the conditions described in e. above, the SiN film expands: E (defective).

[0708] [Synthesis Examples 1 and 2] (Synthesis Example 1-1-1)

[0709] After purging a 500 ml four-necked flask equipped with a reflux tube and a Dean-Stocker tube with nitrogen, 20 g of N-methyl-2-pyrrolidone (NMP) and 22.22 mmol of 9,9-bis(4-aminophenyl)fluorene (44BAFL) were added, and the mixture was stirred until the 44BAFL dissolved. Then, 20.00 mmol of 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), 11.41 g of N-methyl-2-pyrrolidone (NMP), and 21.76 g of toluene were added at 40 °C, and the polymerization reaction was carried out at 180 °C for 4 hours under a nitrogen atmosphere. One hour after reaching 180 °C, a mixture of water and toluene was removed from the Dean-Stocker tube. After 4 hours of reaction, the imide had a weight-average molecular weight (Mw) of 19,178 and a number-average molecular weight (Mn) of 8,283.

[0710] After a 4-hour reaction, the mixture was cooled to an internal temperature of 80°C, and 82.82 mmol of 4-aminophenyl-4'-aminobenzoate (APAB) and 100 g of NMP were added. The APAB was stirred until completely dissolved. After visual confirmation of complete APAB dissolution, 86.17 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added. The mixture was stirred for 1 hour under a nitrogen atmosphere at 80°C, then stirred for 2 hours at 60°C, and finally allowed to polymerize overnight at room temperature. The NMP was then added to adjust the solids content to 12% by mass, thus obtaining an NMP solution of the polyimide-polyamic acid copolymer (hereinafter also referred to as a varnish). The resulting polyamic acid-imide copolymer had a weight-average molecular weight (Mw) of 155,382 and a number-average molecular weight (Mn) of 64,063.

[0711] (Synthesis example 1-1-2)

[0712] (a) Polyimide synthesis

[0713] After purging a 500 ml four-necked flask equipped with a reflux tube and a Dean-Stocker tube with nitrogen, 20 g of N-methyl-2-pyrrolidone (NMP) and 22.22 mmol of 9,9-bis(4-aminophenyl)fluorene (44BAFL) were added, and the mixture was stirred until the 44BAFL dissolved. Then, 20.00 mmol of 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF), 11.41 g of N-methyl-2-pyrrolidone (NMP), and 21.76 g of toluene were added at 40 °C, and the polymerization reaction was carried out at 180 °C for 4 hours under a nitrogen stream. One hour after reaching 180 °C, a mixture of water and toluene was removed from the Dean-Stocker tube. After 4 hours of reaction, the imide had a weight-average molecular weight (Mw) of 19,804 and a number-average molecular weight (Mn) of 8,886. After a 4-hour reaction, the mixture is cooled to an internal temperature of 80°C, and NMP is added to obtain an NMP solution of polyimide with a concentration of 20% by mass (hereinafter also referred to as polyimide varnish).

[0714] (b) Synthesis of polyamic acid

[0715] After purging a 500 ml four-necked flask with nitrogen, 82.82 mmol of 4-aminophenyl-4'-aminobenzoate (APAB) and 100 g of NMP were added, and the APAB was completely dissolved while stirring. After visually confirming complete dissolution of APAB, 86.17 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added. The mixture was stirred for 5 hours under a nitrogen atmosphere at 80°C, and then allowed to polymerize overnight at room temperature. The NMP was then added to adjust the solids content to 20% by mass, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as polyamic acid varnish). The obtained polyamic acid had a weight-average molecular weight (Mw) of 73,044 and a number-average molecular weight (Mn) of 34,917.

[0716] (c) Synthesis of polyamic acid-imide copolymer

[0717] The polyimide varnish obtained in (a) and the polyamic acid varnish obtained in (b) were mixed and stirred at room temperature for 24 hours to obtain an NMP solution of polyamic acid-imide copolymer.

[0718] (Synthesis Example 1-12)

[0719] After purging a 500 ml four-necked flask equipped with a reflux tube and a Dean-Stocker tube with nitrogen, 20 g of N-methyl-2-pyrrolidone (NMP) and 22.22 mmol of 9,9-bis(4-aminophenyl)fluorene (44BAFL) were added, and the mixture was stirred until 44BAFL dissolved. Then, at 40 °C, 10.00 mmol of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), 10.00 mmol of biphenyltetracarboxylic acid dianhydride, 11.41 g of N-methyl-2-pyrrolidone (NMP), and 21.76 g of toluene were added, and the polymerization reaction was carried out at 180 °C for 4 hours under a nitrogen atmosphere. One hour after reaching 180 °C, a mixture of water and toluene was removed from the Dean-Stocker tube. After a 4-hour reaction, the imide had a weight-average molecular weight (Mw) of 19,342 and a number-average molecular weight (Mn) of 9,242.

[0720] After a 4-hour reaction, the mixture was cooled to an internal temperature of 80°C, and 82.82 mmol of 4-aminophenyl-4'-aminobenzoate (APAB) and 100 g of NMP were added. The APAB was stirred until completely dissolved. After visual confirmation that the APAB was completely dissolved, 86.17 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added, and polymerization was carried out at 80°C for 1 hour under a nitrogen atmosphere. Then, the NMP was added to adjust the solids content to 12% by mass, thus obtaining an NMP solution of the polyimide-polyamic acid copolymer (hereinafter also referred to as a varnish). The resulting polyamic acid-imide copolymer had a weight-average molecular weight (Mw) of 40,578 and a number-average molecular weight (Mn) of 19,128.

[0721] (Synthetic Examples 1-2 to 1-11 and 1-13 to 1-30)

[0722] In the above-mentioned synthesis example 1-1-1, the types and amounts of raw materials were changed as described in Table 1, and the process was otherwise the same as in synthesis example 1-1-1 to obtain polyamic acid-imide copolymer varnish.

[0723] (Synthesis example 1-1-3)

[0724] Add 0.04 moles of 1-methylimidazole to the NMP solution synthesized in Synthesis Example 1-1-1 above, relative to 1 mole of the repeating unit of the polyimide-polyamic acid copolymer, to obtain a polyamic acid-imide copolymer varnish.

[0725] (Synthesis example 1-1-4)

[0726] Add 0.13 moles of 1-methylimidazole to the NMP solution synthesized in Synthesis Example 1-1-1 above, relative to 1 mole of the repeating unit of the polyimide-polyamic acid copolymer, to obtain a polyamic acid-imide copolymer varnish.

[0727] (Synthesis example 1-1-5)

[0728] To the NMP solution synthesized in Synthesis Example 1-1-1 above, 0.13 moles of N-Boc-imidazole were added relative to 1 mole of the repeating unit of the polyimide-polyamic acid copolymer to obtain a polyamic acid-imide copolymer varnish.

[0729] (Synthesis example 1-1-6)

[0730] To the NMP solution synthesized in Synthesis Example 1-1-1 above, 0.04 mol of 1-methylimidazole and 0.04 mol of N-Boc-imidazole were added relative to 1 mol of the repeating unit of the polyimide-polyamic acid copolymer to obtain a polyamic acid-imide copolymer varnish.

[0731] (Synthesis example 2-1)

[0732] After purging a 500 ml four-necked flask with nitrogen, 49.50 mmol of 4-aminophenyl-4'-aminobenzoate (APAB) and 80 g of NMP were added, and the APAB was completely dissolved while stirring. After visually confirming complete dissolution of APAB, 50.00 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added. The mixture was stirred for 5 hours under a nitrogen atmosphere at 80°C, and then allowed to polymerize overnight at room temperature. The NMP was then added to adjust the solids content to 12% by mass, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as polyamic acid varnish). The resulting polyamic acid had a weight-average molecular weight (Mw) of 63,353 and a number-average molecular weight (Mn) of 29,472.

[0733] (Synthesis example 2-2)

[0734] After purging a 500 ml four-necked flask with nitrogen, 31.68 mmol of 4-aminophenyl-4'-aminobenzoate (APAB), 7.92 mmol of 9,9-bis(aminophenyl)fluorene (BAFL), and 70 g of NMP were added, stirring until APAB and BAFL were completely dissolved. After visually confirming complete dissolution of APAB and BAFL, 32.00 mmol of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 8.00 mmol of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), and 22.29 g of NMP were added. The mixture was stirred for 5 hours under a nitrogen atmosphere at 80°C, and then allowed to polymerize overnight at room temperature. The NMP was then added to adjust the solids content to 12% by mass, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as polyamic acid varnish). The obtained polyamic acid had a weight-average molecular weight (Mw) of 72,118 and a number-average molecular weight (Mn) of 33,741.

[0735] (Synthesis example 2-3)

[0736] A polyamic acid-imide copolymer varnish was synthesized using the same method as in Example 1 of International Publication No. 2020 / 138360.

[0737] (Synthesis example 2-4)

[0738] Polyimide varnish was synthesized using the same method as in Example 1 of International Publication No. 2019 / 188305.

[0739] The abbreviations for the components in the table below have the following meanings.

[0740] BPDA: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride

[0741] ODPA: 4,4'-O-diphthalic anhydride

[0742] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene anhydride

[0743] TAHQ: p-Phenylidene bis(triphenyltriglyceride)

[0744] BPF-PA: 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene anhydride

[0745] 6FDA: 4,4'-(hexafluoroisopropylidene)phthalic anhydride

[0746] APAB: 4-Aminophenyl-4'-aminobenzoate

[0747] pPD: p-phenylenediamine

[0748] 44BAFL: 9,9-bis(4-aminophenyl)fluorene

[0749] 33BAFL: 9,9-bis(3-aminophenyl)fluorene

[0750] BFAF: 9,9-bis(3-fluoro-4-aminophenyl)fluorene

[0751] 33DAS: 3,3'-Diaminodiphenylsulfone

[0752] 44DAS: 4,4'-Diaminodiphenylsulfone

[0753] 44ODA: 4,4'-Diaminodiphenyl ether

[0754] 34ODA: 3,4'-Diaminodiphenyl ether

[0755] BAOFL: 9,9-bis[4-(aminophenoxy)phenyl]fluorene

[0756] BAHF: 9,9-bis[3-amino-4-hydroxyphenyl]fluorene

[0757] NMP: N-methyl-2-pyrrolidone

[0758] DMF: N,N-dimethylformamide

[0759] <Implementation Method I>

[0760] The varnishes obtained in each synthesis example were used directly as resin compositions and evaluated according to the methods described above. The synthesis results are shown in Table 1, and the evaluation results are shown in Tables 2 to 4.

[0761] As shown in Tables 1 and 2, the polyimide film composed solely of structural unit N (polyamic acid) (Comparative Example 1-1) exhibits excellent residual stress, but its YI and Haze values ​​are high. Furthermore, the polyimide film obtained from polyamic acid synthesized according to the same composition as the polyamic acid-imide copolymer described in Comparative Examples 1-2 (the molar ratio of monomers constituting X1 to X4 is the same) exhibits excellent YI and Haze values, but its residual stress is high, failing to demonstrate performance suitable for use as a substrate for optical displays.

[0762] Furthermore, polyimide films (Comparative Examples 1-3) obtained from polyamic acid-imide copolymers obtained by the method described in Example 1 of International Publication No. 2020 / 138360, without using general formula (A-1) or (A-2) as X2 in structural unit N, turned yellow during the 430°C heat treatment process, exhibiting high YI and Haze values. In contrast, polyimide films (Comparative Examples 1-4) obtained from polyimides composed solely of structural unit M (polyimide), obtained by the method described in Example 1 of International Publication No. 2019 / 188305, suppressed yellowing during the 430°C heat treatment process; however, they exhibited high residual stress and did not demonstrate performance suitable for use as substrates for optical displays.

[0763] On the other hand, the polyimide films obtained from polyamic acid-imide copolymers comprising structural units shown in general formula (1) and structures shown in general formulas (A-1) or (A-2) as X2, as described in Examples 1-1 to 1-30, exhibit a yellowness (YI value) as low as 15 or less and a haze (Haze value) as low as 0.5%, possessing performance sufficient for use as substrates for optical displays. Furthermore, the residual stress is as low as 25 MPa or less, and the mechanical properties are also sufficient. From the above results, it can be confirmed that the polyimide resin film obtained from the resin composition of the present invention is a resin film with low yellowness, low haze, and low residual stress.

[0764] Specifically, the present invention yields resin films with residual stress below 25 MPa, yellowness below 15, and haze below 0.5%.

[0765] Alternatively, after synthesizing polyamic acid and polyimide separately as in Synthesis Example 1-1-2, mixing them yields a polyamic acid-imide copolymer varnish obtained through reaction. The polyimide film obtained from this varnish, as shown in Example 1-1-2, exhibits the same properties as in Example 1-1-1. This demonstrates that by mixing and reacting synthesized (a) polyamic acid and (b) polyimide in a specified molar ratio, (c) a polyamic acid-imide copolymer can be obtained.

[0766] In addition, in Examples 1-8, where the molar ratio of polyamic acid structural unit N composed of X1 and X2 to polyimide structural unit M composed of X3 and X4 in Table 2 is 60:40 (number of moles of structural unit N: number of moles of structural unit M), transparent films with excellent yellowness and haze were obtained, the residual stress was as low as 25 MPa or less, and the mechanical properties were also sufficient.

[0767] Furthermore, as shown in Examples 1-6, 1-14, and 1-15 of Table 2, when the X4 / X3 ratio is 1.01 to 2, i.e., the ratio of diamine to acid dianhydride is increased, the proportion of polyimide terminal amines increases. This increases the reactivity of polyamic acid with polyimide during reaction, resulting in good dispersion of polyimide particles when forming a film. Therefore, a transparent film with excellent yellowness (YI value) and haze (Haze value) is obtained. Additionally, as shown in Examples 1-6, 1-14, and 1-15, the composition with an X4 / X3 ratio of 1.11 has a low yellowness (YI value) and is particularly preferred.

[0768] Furthermore, as shown in Examples 2-2 to 2-5 in Table 3, the films obtained from polyimide-polyamic acid copolymers containing 1-methylimidazolium or N-Boc-imidazolium as imidization catalysts have low yellowness (YI value) and can be preferably used as substrates for displays.

[0769] In addition, as shown in Comparative Example 2-1 (Synthesis Example 2-1) in Table 4, the polyimide film obtained from polyamic acid containing only structural unit N has a high elastic modulus at 25°C and 350°C, and does not expand or crack after being reheated at 430°C after sputtering Al. However, it has a high YI value, which is insufficient for use as a substrate for optical displays.

[0770] Furthermore, as shown in Comparative Example 2-2 (Synthetic Example 2-2) in Table 4, when the elastic modulus at 350°C is low, expansion or cracking occurs when Al is sputtered and then reheated at 430°C. This is believed to be because the polyimide content is high and the elastic modulus at high temperatures is low, thus increasing the difference in shrinkage force between Al and polyimide in the high-temperature region above 350°C, leading to cracking or expansion.

[0771] On the other hand, when the elastic modulus at 350°C is 0.5 GPa or higher, even in high-temperature regions, the film does not rupture or expand due to its high strength, making it a preferred substrate for displays. Furthermore, as shown in Examples 3-1 to 3-3 in Table 4, films with high elastic modulus at 350°C and a haze value of 0.5% or less that do not undergo phase separation exhibit a small rate of change in YI value during reheating at 430°C, making them a preferred substrate for displays.

[0772] Specifically, the present invention yields resin films with an elastic modulus of 6 GPa or more at 25°C, an elastic modulus of 0.5 GPa or more at 350°C, and a haze of 0.5% or less.

[0773] [Table 1]

[0774]

[0775] [Table 2]

[0776]

[0777] [Table 3]

[0778]

[0779] [Table 4]

[0780]

[0781] <Implementation Method IV>

[0782] (Synthesis Example 1-31)

[0783] The amount of APAB in Synthesis Example 1-1-1 was changed to 83.02 mmol, and the process was otherwise the same as in Synthesis Example 1-1-1. The weight-average molecular weight (Mw) of the resulting polyamic acid-imide copolymer was 173,000.

[0784] (Synthesis example 1-32)

[0785] The BAFL in Synthesis Example 1-1-1 was changed to 33DAS, and the amount of APAB was changed to 83.02 mmol. Otherwise, the process was the same as in Synthesis Example 1-1-1. The weight-average molecular weight (Mw) of the resulting polyamic acid-imide copolymer was 171,000.

[0786] (Synthesis Example 1-33)

[0787] The amount of APAB in Synthesis Example 1-1-1 was changed to 83.45 mmol, and the process was otherwise the same as in Synthesis Example 1-1-1. The weight-average molecular weight (Mw) of the resulting polyamic acid-imide copolymer was 224,000.

[0788] (Synthesis Example 1-34)

[0789] The BAFL in Synthesis Example 1-1-1 was changed to 33DAS, and the amount of APAB was changed to 83.45 mmol. Otherwise, the process was the same as in Synthesis Example 1-1-1. The weight-average molecular weight (Mw) of the resulting polyamic acid-imide copolymer was 221,000.

[0790] (Synthesis example 3-1)

[0791] To a 5L detachable flask purged with nitrogen, add an amount equivalent to 25wt% of the solid content of a freshly opened 18L can of N-methyl-2-pyrrolidone (NMP) (250 ppm water), along with 180.77 g (800 mmol) of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Junryu Pharmaceutical Co., Ltd., Japan), and stir until APAB is dissolved. Then, add 235.38 g (792 mmol) of biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA, 99.5% purity, manufactured by Manac Incorporated.), and proceed with the polymerization reaction for 5 hours under a nitrogen flow, at 70°C, and with stirring. The mixture is then cooled to room temperature and allowed to stand for 8 days under a nitrogen flow. The viscosity of the solution is adjusted to 10,000 mPa·s by adding the aforementioned NMP, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 152,000.

[0792] (Synthesis example 3-2)

[0793] To a 5L detachable flask purged with nitrogen, add an amount equivalent to 25wt% of the solid content of a freshly opened 18L can of N-methyl-2-pyrrolidone (NMP) (250 ppm water), along with 181.69 g (800 mmol) of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Junryu Pharmaceutical Co., Ltd., Japan), and stir until APAB is dissolved. Then, add 235.38 g (796 mmol) of biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA, 99.5% purity, manufactured by Manac Incorporated.), and proceed with the polymerization reaction for 5 hours under a nitrogen flow, at 70°C, and with stirring. The mixture is then cooled to room temperature and allowed to stand for 8 days under a nitrogen flow. The viscosity of the solution is adjusted to 10,000 mPa·s by adding the aforementioned NMP, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as a varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 175,000.

[0794] (Synthesis example 3-3)

[0795] To a 5L detachable flask purged with nitrogen, add an amount equivalent to 25wt% of the solids content of a freshly opened 18L can of N-methyl-2-pyrrolidone (NMP) (250 ppm water), 145.35 g (637 mmol) of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Junryu Pharmaceutical Co., Ltd., Japan) and 39.53 g (159 mmol) of 4,4'-diaminodiphenyl sulfone (4,4'-DAS, 99.5% purity, SEIKA CORP) and stir until APAB and 4,4'-DAS are dissolved. Then, add 235.38 g (800 mmol) of biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA, 99.5% purity, manufactured by Manac Incorporated.) and carry out a polymerization reaction for 5 hours under a nitrogen atmosphere, at 70°C, and with stirring. Then, it was cooled to room temperature and allowed to stand for 8 days under a nitrogen atmosphere. The viscosity of the solution was adjusted to 10,000 mPa·s by adding the above-mentioned NMP, thereby obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 173,000.

[0796] (Synthesis Example 3-4)

[0797] To a 5L detachable flask purged with nitrogen, add an amount equivalent to 25wt% of the solid content of a freshly opened 18L can of N-methyl-2-pyrrolidone (NMP) (250 ppm water), along with 181.69 g (800 mmol) of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Junryu Pharmaceutical Co., Ltd., Japan), and stir until APAB is dissolved. Then, add 235.38 g (796 mmol) of biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA, 99.5% purity, manufactured by Manac Incorporated.), and proceed with the polymerization reaction for 5 hours under a nitrogen flow, at 70°C, and with stirring. The mixture is then cooled to room temperature and allowed to stand for 8 days under a nitrogen flow. The viscosity of the solution is adjusted to 10,000 mPa·s by adding the aforementioned NMP, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as a varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 242,000.

[0798] (Synthesis Example 3-5)

[0799] To a nitrogen-purged 5L detachable flask, add an amount equivalent to 25 wt% of the solid content of a freshly opened 18L can of N-methyl-2-pyrrolidone (NMP) (250 ppm water), along with 182.42 g (800 mmol) of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Junryu Pharmaceutical Co., Ltd., Japan), and stir until APAB is dissolved. Then, add 235.38 g (799 mmol) of biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA, 99.5% purity, manufactured by Manac Incorporated.), and proceed with the polymerization reaction for 5 hours under a nitrogen flow, at 70°C, and with stirring. The mixture is then cooled to room temperature and allowed to stand for 8 days under a nitrogen flow. The viscosity of the solution is adjusted to 10,000 mPa·s by adding the aforementioned NMP, thus obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 241,000.

[0800] (Synthesis Example 3-6)

[0801] To a 1L detachable flask purged with nitrogen, add an amount equivalent to 25wt% of freshly opened 18L canisters of N-methyl-2-pyrrolidone (NMP) (250 ppm water), along with 80 mmol of 4-aminophenyl-4-aminobenzoate (APAB, 99.5% purity, manufactured by Nippon Junryu Pharmaceutical Co., Ltd.), and stir until APAB is dissolved. Then, add 79.6 mmol of bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 2,2',3,3',5,5'-hexamethylbiphenyl-4,4'-diyl ester (manufactured by Honshu Chemical Industry Co., Ltd.), and proceed with the polymerization reaction for 5 hours under a nitrogen atmosphere, at 70°C, and with stirring. Then, cool to room temperature and allow to stand for 8 days under a nitrogen atmosphere. The solution viscosity was adjusted to 10,000 mPa·s by adding the aforementioned NMP, thereby obtaining an NMP solution of polyamic acid (hereinafter also referred to as varnish). The weight-average molecular weight (Mw) of the obtained polyamic acid was 172,000.

[0802] (Refer to Example 4-1)

[0803] The above-mentioned IR curing defect evaluation and degassing evaluation were performed using NMP solution of the polyimide-polyamic acid copolymer (hereinafter also referred to as PAI) synthesized in Synthesis Example 1-1-1. The results are recorded in Table 6.

[0804] (Example 4-1)

[0805] Using the NMP solution of the polyimide-polyamic acid copolymer synthesized in Synthetic Examples 1-32, 1 part by mass of imidization catalyst 1 (1-methylimidazole) as described in Table 6 was added relative to 100 parts by mass of the polyimide-polyamic acid copolymer. The mixture was stirred at room temperature for 24 hours to obtain a polyamic acid-imide copolymer varnish. The varnish was used to evaluate the above-mentioned IR curing defects and degassing. The results are recorded in Table 6.

[0806] (Examples 4-2 to 30)

[0807] Using the NMP solution of the polyimide-polyamic acid copolymer described in Table 6, the imidization catalyst described in Table 5 was added in the amounts described in Table 6, and the process was otherwise identical to that in Example 4-1 to obtain a polyamic acid-imide copolymer varnish. The obtained varnish was then used to perform the aforementioned IR curing defect evaluation and degassing evaluation. The results are recorded in Table 6.

[0808] (Example 4-31)

[0809] Using the NMP solution of the polyimide-polyamic acid copolymer as described in Table 6, the imidization catalyst as described in Table 5 was added in the amounts described in Table 6. Furthermore, 20 parts by mass of sulfolane, an aprotic polar substance with a boiling point of 250-350°C, were added relative to 100 parts by mass of NMP. Otherwise, the process was the same as in Example 4-1 to obtain a polyamic acid-imide copolymer varnish. The obtained varnish was used for the aforementioned IR curing defect evaluation and degassing evaluation. The results are recorded in Table 6.

[0810] (Comparative Example 5-1)

[0811] The above-mentioned IR curing defect evaluation and degassing evaluation were performed using NMP solution of polyamic acid (hereinafter also referred to as PAA) synthesized in Synthesis Example 3-1. The results are recorded in Table 7.

[0812] (Example 5-1)

[0813] Using the NMP solution of polyamic acid synthesized in Synthesis Example 3-2, 1 part by mass of imidization catalyst 1 (1-methylimidazole) as described in Table 5 was added relative to 100 parts by mass of the polyamic acid copolymer. The mixture was stirred at room temperature for 24 hours to obtain a polyamic acid varnish. The varnish was then used to evaluate the above-mentioned IR curing defects and degassing. The results are recorded in Table 7.

[0814] (Examples 5-2 to 29, Comparative Example 5-2)

[0815] Using the NMP solution of polyamic acid as described in Table 7, the imidization catalyst as described in Table 5 was added in the amounts described in Table 7, and the process was otherwise identical to that in Example 5-1 to obtain a polyamic acid varnish. The obtained varnish was then used for the aforementioned IR curing defect evaluation and degassing evaluation. The results are shown in Table 7.

[0816] (Examples 5-30)

[0817] Using the NMP solution of polyamic acid as described in Table 7, the imidization catalyst described in Table 5 was added in the amounts described in Table 7. Furthermore, 20 parts by mass of sulfolane, an aprotic polar substance with a boiling point of 250-350°C, were added relative to 100 parts by mass of NMP. Otherwise, the process was the same as in Example 5-1 to obtain a polyamic acid varnish. The obtained varnish was used to perform the aforementioned IR curing defect evaluation and degassing evaluation. The results are recorded in Table 7.

[0818] [Table 5]

[0819] Imidization catalyst Compound Name 1 1-Methylimidazole 2 N-Boc-imidazole 3 2-Methylimidazole 4 2-Phenylidene 5 benzimidazole 6 2-Ethyl-4-methylimidazolium 7 4-Ethyl-2-methylimidazolium 8 4-Methyl-2-phenylimidazole 9 2-Undecylimidazol 10 1-Benzyl-2-methylimidazolium 11 1-Benzyl-2-phenylimidazolium 12 1H-Imidazole 13 1,2-Dimethylimidazole 14 4-Dimethylaminopyridine 15 2,2'-Bipyridine 16 Nicotinic acid-pyridinecarboxylic acid 17 Isoquinoline 18 Pyridine 19 2-Methylpyridine 20 1,8-diazabicyclo[5.4.0]-7-undecene 21 1,4-Diazabicyclo[2.2.2]octane 22 N-Methylmorpholine 23 Triethylamine

[0820] [Table 6]

[0821] Table 6

[0822]

[0823] [Table 7]

[0824] Table 7

[0825]

[0826] <Implementation Method II>

[0827] The varnishes obtained in each synthesis example were used directly as resin compositions and evaluated according to the methods described above. The synthesis results are shown in Table 8, and the evaluation results are shown in Tables 9 and 10.

[0828] As shown in Tables 8 and 9, the polyimide film composed solely of structural unit N (polyamic acid) (Comparative Example II-1-1) exhibits excellent residual stress, but its YI and Haze values ​​are high. Furthermore, the polyimide film obtained from polyamic acid synthesized according to the same composition as the polyamic acid-imide copolymer described in Example II-1-1 (the molar ratio of monomers constituting X1 to X4 is the same) also exhibits excellent YI and Haze values, but its residual stress is high. Neither of these materials demonstrates performance sufficient for use as a substrate for optical displays.

[0829] Furthermore, the polyimide film (Comparative Example II-1-3) obtained from the polyamic acid-imide copolymer obtained by the method described in Example 1 of International Publication No. 2020 / 138360, which does not use general formula (A-1) or (A-2) as X2 in structural unit N, turns yellow during the 430°C heat treatment process, and has high YI and Haze values. On the other hand, the polyimide film (Comparative Example II-1-4) obtained from the polyimide obtained by the method described in Example 1 of International Publication No. 2019 / 188305, which consists only of structural unit M (polyimide), suppresses yellowing during the 430°C heat treatment process, but has high residual stress and does not exhibit performance suitable for use as a substrate for optical displays.

[0830] On the other hand, as shown in Example II-1-1-1, the polyimide film obtained from a polyamic acid-imide copolymer comprising at least one of the following as X3: a structure selected from the group consisting of the structure shown in general formula (A-1), a structure derived from 4,4'-oxyphthalic anhydride (ODPA), and a structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). This polyimide film exhibits a yellowness (YI value) as low as 15 or less and a haze (Haze value) as low as 0.5%, thus possessing performance sufficient for use as a substrate for optical displays. Furthermore, the residual stress is as low as 25 MPa or less, and it also exhibits excellent bending resistance and sufficient mechanical properties. From the above results, it can be confirmed that the polyimide resin film obtained from the resin composition of the present invention is a resin film with low yellowness, low haze, and low residual stress.

[0831] Specifically, the present invention yields a resin film with residual stress below 25 MPa, yellowness below 15, haze below 0.5%, and excellent bending resistance.

[0832] Alternatively, after synthesizing polyamic acid and polyimide separately as in Synthesis Example 1-1-2, mixing them yields a polyamic acid-imide copolymer varnish obtained through reaction. The polyimide film obtained from this varnish, as shown in Example II-1-1-2, exhibits the same properties as in Example II-1-1-1. This demonstrates that by mixing and reacting synthesized (b) polyamic acid and (a) polyimide in a specified molar ratio, (c) polyamic acid-imide copolymer can be obtained.

[0833] On the other hand, as shown in Comparative Example II-1-1 in Table 9, the polyimide film obtained from polyamic acid containing only structural unit N exhibits excellent residual stress, but its bending resistance is insufficient. This is believed to be because the polyimide film containing only structural unit N is very rigid, thus in-plane crystallization propagates during bending tests, resulting in scratches. Therefore, the polyimide copolymer film obtained from polyamic acid-imide copolymers containing both structural units N and M exhibits excellent yellowness and haze, low residual stress, and excellent bending resistance.

[0834] Furthermore, as shown in Examples II-1-6, II-1-12, and II-1-13, when the X4 / X3 ratio is 1.01 to 2, i.e., the ratio of diamine to acid dianhydride is increased, the proportion of polyimide terminal amines increases. This increases the reactivity of polyamic acid with polyimide during reaction, resulting in good dispersion of polyimides when forming a film. Therefore, a transparent film with excellent yellowness (YI value), haze (Haze value), and flexural strength is obtained. Additionally, as shown in Examples II-1-6, II-1-12, and II-1-13, a composition with an X4 / X3 ratio of 1.11 has a low yellowness (YI value) and is particularly preferred.

[0835] Furthermore, as shown in Examples II-2-1 to II-2-5 in Table 10, the films obtained from polyimide-polyamic acid copolymers containing 1-methylimidazolium or N-Boc-imidazolium as imidization catalysts have low yellowness (YI value) and can be preferably used as substrates for displays.

[0836] [Table 8]

[0837]

[0838] [Table 9]

[0839]

[0840] [Table 10]

[0841]

[0842] <Implementation Method III>

[0843] [Example III-1]

[0844] The 500ml detachable flask was purged with nitrogen. An amount of freshly opened 18L can of N-methylpyrrolidone (NMP: 250ppm water) as a solvent, equivalent to 15wt% of the solid content, was added to the detachable flask. 15.69g (49.0mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added and stirred until the TFMB was dissolved. Then, 9.27 g (42.5 mmol) of pyromellitic dianhydride (PMDA) and 3.33 g (7.5 mmol) of 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) were added. The mixture was stirred for 4 hours under a nitrogen atmosphere at 80°C. After cooling to room temperature, sulfolane, an aprotic polar substance with a boiling point of 250°C to 350°C, was added at a ratio of 100 wt% (mass of solvent + mass of sulfolane) to 3 wt%. The mixture was stirred for another hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0845] The varnish was spin-coated onto a 6-inch silicon wafer and a 10cm square EAGLE glass plate using a MIKASA coater. After pre-baking on a hot plate at 100°C for 6 minutes, it was placed in an oven and cured at 380°C for 1 hour under a nitrogen atmosphere to obtain a polyimide resin film. For the polyimide resin film formed on the silicon wafer, the film thickness at 39 locations in the plane was measured using a Lambda ACE. The value obtained by dividing [(film thickness with the largest deviation from the average) - (average film thickness)] by the average film thickness (hereinafter also referred to as in-plane film thickness uniformity) was 6.0%.

[0846] For the polyimide resin film formed on EAGLE glass, YI was measured using a haze meter, and the result was converted to 7.9 based on a film thickness of 10 μm.

[0847] In addition, the polyimide resin film formed on the EAGLE glass was reheated to 400°C, and the gas composition generated was analyzed by GCMS. Sulfolane was not detected.

[0848] [Example III-2]

[0849] In Example III-1, the amount of sulfolane added was changed from 3 wt% to 20 wt%, and the polyamic acid solution was obtained in the same manner as in Example III-1. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 2.0%, 7.3%, and 0 ppm, respectively.

[0850] [Example III-3]

[0851] A 500ml detachable flask was purged with nitrogen. An 18L container of freshly opened N-methylpyrrolidone (NMP: 250ppm water) was added as a solvent, with a solid content equivalent to 15wt%. 15.69g (49.0mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added, and the mixture was stirred until the TFMB dissolved. Then, 9.27g (42.5mmol) of pyromellitic dianhydride (PMDA) and 3.33g (7.5mmol) of 4,4'-(hexafluoroisopropylidene)phthalic dianhydride (6FDA) were added. The mixture was stirred at 80°C for 4 hours under a nitrogen atmosphere. After cooling to room temperature, the solution was added dropwise to 6 times its volume of water while stirring, causing the polymer to precipitate. The polymer was filtered off and then vacuum dried at 40°C for 24 hours. The polymer was then dissolved in sulfolane at a concentration of 15 wt% to obtain a polyamic acid solution. This varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, yielding results of 2.0%, 7.3%, and 600 ppm, respectively.

[0852] [Comparative Example III-1]

[0853] In Example III-1, sulfolane was not added, but otherwise a solution of polyamic acid was obtained in the same manner as in Example III-1. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 8.1%, and 0 ppm, respectively.

[0854] [Example III-4]

[0855] In Example III-2, sulfolane was replaced with 3-methylsulfolane, and the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 2.0%, 7.6%, and 0 ppm, respectively.

[0856] [Example III-5]

[0857] In Example III-2, sulfolane was replaced with benzophenone, and otherwise the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 4.2%, 7.4%, and 0 ppm, respectively.

[0858] [Example III-6]

[0859] In Example III-2, sulfolane was replaced with 2-phenoxyethyl acetate, and the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 3.3%, 7.6%, and 0 ppm, respectively.

[0860] [Example III-7]

[0861] In Example III-2, sulfolane was replaced with diphenyl carbonate, and otherwise the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 3.0%, 7.5%, and 0 ppm, respectively.

[0862] [Example III-8]

[0863] In Example III-2, sulfolane was replaced with adipamide, and otherwise a polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 4.1%, 7.6%, and 0 ppm, respectively.

[0864] [Example III-9]

[0865] In Example III-2, sulfolane was replaced with adiponitrile, and otherwise a polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 4.0%, 7.5%, and 0 ppm, respectively.

[0866] [Example III-10]

[0867] In Example III-2, sulfolane was replaced with dibutyl sulfoxide, and otherwise the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 3.0%, 7.6%, and 0 ppm, respectively.

[0868] [Comparative Example III-2]

[0869] In Example III-2, sulfolane was replaced with dimethyl sulfone, and otherwise the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 8.1%, and 0 ppm, respectively.

[0870] [Comparative Example III-3]

[0871] In Example III-2, sulfolane was replaced with diphenyl sulfone, and otherwise the polyamic acid solution was obtained in the same manner as in Example III-2. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 4.0%, 7.5%, and 1500 ppm, respectively.

[0872] [Example III-11]

[0873] A 500 ml detachable flask was purged with nitrogen. An 18 L can of freshly opened N-methylpyrrolidone (NMP: 250 ppm water) was added as a solvent, equivalent to 20 wt% of the solid content. 8.95 g (39.2 mmol) of 4-aminobenzoic acid (APAB) and 2.43 g (9.8 mmol) of 4,4'-diaminophenyl sulfone (4,4'-DAS) were then added and stirred until dissolved. Next, 14.71 g (50 mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) was added. The mixture was stirred for 4 hours under a nitrogen atmosphere at 80°C. After cooling to room temperature, sulfolane was added at a concentration of 20 wt% when (solvent mass + sulfolane mass) was 100 wt%. The mixture was stirred for another hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0874] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.2%, 12.6%, and 0 ppm, respectively.

[0875] [Comparative Example III-4]

[0876] In Example 11, sulfolane was not added, and the polyamic acid solution was obtained in the same manner as in Example III-11. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 11.0%, 13.5%, and 0 ppm, respectively.

[0877] [Example III-12]

[0878] A 500ml detachable flask was purged with nitrogen. 22.2g of freshly opened 18L can of N-methylpyrrolidone (NMP: 250ppm water) and 2.61g (10.53mmol) of 3,3'-diaminophenyl sulfone (3,3'-DAS) were added to the flask as solvent. After stirring to dissolve, 2.94g (9.47mmol) of 4,4'-oxophthalic dianhydride (ODPA) and 20g of toluene were added. A reflux tube and a Dean-Stocker tube were installed on the flask. The reaction was carried out under a nitrogen atmosphere at 180°C for 2 hours, while the water produced was extracted from the Dean-Stocker tube. The mixture was then heated at 180°C for 1 hour, and all the added toluene was extracted from the Dean-Stocker tube. Then, the reaction solution was cooled to room temperature, and 81.96 g of freshly opened N-methylpyrrolidone (NMP: 250 ppm water), 11.77 g (40 mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), and 8.72 g (38.2 mmol) of 4-aminobenzoic acid (APAB) were added as solvents and stirred until dissolved. The reaction was then carried out under a nitrogen atmosphere at 80°C for 4 hours. After cooling to room temperature, sulfolane was added at a concentration of 20 wt% when (mass of solvent + mass of sulfolane) was 100 wt%, and the mixture was stirred for another hour to obtain a polyamic acid-soluble polyimide solution (hereinafter also referred to as varnish).

[0879] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.3%, 12.9%, and 0 ppm, respectively.

[0880] [Comparative Example III-5]

[0881] In Example III-12, sulfolane was not added, but otherwise a polyamic acid-soluble polyimide solution was obtained in the same manner as in Example III-12. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 13.6%, and 0 ppm, respectively.

[0882] [Example III-13]

[0883] A 500 ml detachable flask was purged with nitrogen. An amount of freshly opened 18 L N-methylpyrrolidone (NMP: 250 ppm water) was added as a solvent, equivalent to 20 wt% of the solid content. 17.07 g (49 mmol) of 9,9-bis(4-aminophenyl)fluorene (BAFL) was added, and the mixture was stirred until the BAFL dissolved. Then, 22.92 g (50 mmol) of 9,9-bis(3,4-dicarboxyphenyl)fluorenic dianhydride (BPAF) was added, and the mixture was stirred at 80°C for 4 hours under a nitrogen atmosphere. After cooling to room temperature, sulfolane was added at a concentration of 20 wt% when (mass of solvent + mass of sulfolane) was 100 wt%. The mixture was stirred for another hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0884] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.1%, 12.8%, and 0 ppm, respectively.

[0885] [Comparative Example III-6]

[0886] In Examples III-13, sulfolane was not added, but otherwise the polyamide-imide solution was obtained in the same manner as in Example III-13. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 13.5%, and 0 ppm, respectively.

[0887] [Example III-14]

[0888] A 300 ml detachable flask was purged with nitrogen. Dimethylacetamide (DMAc) as a solvent, in an amount equivalent to 26 wt% of the solid content, was added to the flask. 2.27 g (10 mmol) of 4,4'-diaminobenzoylaniline (DABAN) was added, and the mixture was stirred until the DABAN dissolved. Then, 3.84 g (10 mmol) of norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2'-norcamphene-5,5',6,6'-tetracarboxylic acid dianhydride (CpODA) was added. After stirring for 12 hours at room temperature under a nitrogen atmosphere, 3-methylcyclobutane was added in such a way that (mass of solvent + mass of 3-methylcyclobutane) equals 20 wt% when 100 wt%. The mixture was stirred further for 1 hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0889] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.4%, 1.5%, and 0 ppm, respectively.

[0890] [Comparative Example III-7]

[0891] In Examples III-14, 3-methylcyclobutanesulfone was not added, but otherwise a solution of polyamic acid was obtained in the same manner as in Example III-14. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 11.0%, 2.3%, and 0 ppm, respectively.

[0892] [Example III-15]

[0893] A 500 ml detachable flask was purged with nitrogen. An amount of freshly opened 18 L N-methylpyrrolidone (NMP: 250 ppm water) was added as solvent, equivalent to 15 wt% of the solid content. 5.6 g (49 mmol) of 1,4-cyclohexanediamine (1,4-CHDA) was added, and the mixture was stirred until dissolved. Then, 13.8 g (47.5 mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and 0.7 g (1.5 mmol) of p-phenylene bis(triphenylene)trimethylammonium dianhydride (TMHQ) were added. The mixture was stirred for 1 hour under a nitrogen atmosphere at 80°C. After stirring at room temperature for 5 hours, sulfolane was added at a concentration of 20 wt% when (mass of solvent + mass of sulfolane) was 100 wt%. The mixture was stirred for another hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0894] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.2%, 1.6%, and 0 ppm, respectively.

[0895] [Example III-16]

[0896] A 500 ml detachable flask was purged with nitrogen. An 18 L container of freshly opened N-methylpyrrolidone (NMP: 250 ppm water) was added as a solvent, equivalent to 15 wt% of the solid content. 5.6 g (49 mmol) of 1,4-cyclohexanediamine (1,4-CHDA) was added, and the mixture was stirred until dissolved. Then, 13.8 g (47.5 mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and 0.7 g (1.5 mmol) of p-phenylene bis(triphenylene) dianhydride (TMHQ) were added. The mixture was stirred at 80°C for 1 hour under a nitrogen atmosphere and at room temperature for 5 hours. Then, the solution was added dropwise to 6 times its volume of water while stirring, causing the polymer to precipitate. After filtering out the polymer, it was vacuum dried at 40°C for 24 hours. The polymer was then dissolved in sulfolane at 15 wt% to obtain a polyamic acid solution. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.2%, 1.6, and 600 ppm, respectively.

[0897] [Comparative Example III-8]

[0898] In Examples III-15, sulfolane was not added, but otherwise a polyamic acid solution was obtained in the same manner as in Example III-15. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 2.3%, and 0 ppm, respectively.

[0899] [Example III-17]

[0900] Add 168 g of γ-butyrolactone (GBL) and 15.2 g (100 mmol) of 3,5-diaminobenzoic acid (DABA) to a 500 ml detachable flask. After stirring to dissolve, add 38.4 g (100 mmol) of norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2'-norcamphene-5,5',6,6'-tetracarboxylic acid dianhydride (CpODA) and 30 g of toluene. Attach a reflux tube and a Dean-Stocker tube to the flask. Under a nitrogen atmosphere at 180 °C, remove the water produced from the Dean-Stocker tube while reacting for 2 hours. Then heat at 180 °C for 1 hour, removing all the added toluene from the Dean-Stocker tube. Sulfolane was added in such a way that (mass of solvent + mass of sulfolane) was 100 wt% to become 20 wt%, and the mixture was stirred for another hour to obtain a solution of soluble polyimide (hereinafter also referred to as varnish).

[0901] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.5%, 1.4%, and 0 ppm, respectively.

[0902] [Example III-18]

[0903] In Example III-17, the amount of sulfolane added was changed from 20 wt% to 50 wt%, and the polyamic acid solution was obtained in the same manner as in Example III-17. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 2.5%, 1.4, and 600 ppm, respectively.

[0904] [Comparative Example III-9]

[0905] Add 168 g of γ-butyrolactone (GBL) and 15.2 g (100 mmol) of 3,5-diaminobenzoic acid (DABA) to a 500 ml detachable flask. After stirring to dissolve, add 38.4 g (100 mmol) of norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2'-norcamphene-5,5',6,6'-tetracarboxylic acid dianhydride (CpODA) and 30 g of toluene. Attach a reflux tube and a Dean-Stocker tube to the flask. Under a nitrogen atmosphere at 180 °C, remove the generated water from the Dean-Stocker tube while reacting for 2 hours. Then heat at 180 °C for 1 hour, removing all added toluene from the Dean-Stocker tube. Next, while stirring, add the solution dropwise to 6 times its volume of water to precipitate the polymer. After filtering the polymer, vacuum dry it at 40 °C for 24 hours. The polymer was then dissolved in sulfolane at a concentration of 15 wt% to obtain a solution of soluble polyimide. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 2.5%, 1.4%, and 1500 ppm, respectively.

[0906] [Comparative Example III-10]

[0907] In Example III-17, sulfolane was not added, but otherwise a polyamic acid solution was obtained in the same manner as in Example III-17. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.6%, 2.2%, and 0 ppm, respectively.

[0908] [Example III-19]

[0909] Add 130 g of N-methylpyrrolidone (NMP: 250 ppm water) and 32.858 g (97.7 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA) to a 500 ml detachable flask. After stirring to dissolve, add 22.936 g (60 mmol) of norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2'-norcamphene-5,5',6,6'-tetracarboxylic acid dianhydride (CpODA) and 30 g of toluene. Attach a reflux tube and a Dean-Stocker tube to the flask. Under a nitrogen atmosphere at 180 °C, remove the water produced from the Dean-Stocker tube while reacting for 2 hours. Then heat at 180 °C for 1 hour, removing all the added toluene from the Dean-Stocker tube. After cooling the solution to 50°C, 25 g of NMP and 11.704 g (40 mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) were added. The mixture was stirred at 50°C for 4 hours, cooled to room temperature, and then 2 mmol (2 g) of organosilicon diamine X-22-1660-B-32 (Shin-Etsu Chemical) was added. The mixture was stirred for 1 hour. Then, sulfolane was added at a concentration of 20 wt% when (mass of solvent + mass of sulfolane) was 100 wt%, and the mixture was stirred for another hour to obtain a polyamic acid-soluble polyimide solution (hereinafter also referred to as varnish).

[0910] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.2%, 1.3%, and 0 ppm, respectively.

[0911] [Example III-20]

[0912] Add 130 g of N-methylpyrrolidone (NMP: 250 ppm water) and 32.858 g (97.7 mmol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA) to a 500 ml detachable flask. After stirring to dissolve, add 22.936 g (60 mmol) of norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2'-norcamphene-5,5',6,6'-tetracarboxylic acid dianhydride (CpODA) and 30 g of toluene. Attach a reflux tube and a Dean-Stocker tube to the flask. Under a nitrogen atmosphere at 180 °C, remove the water produced from the Dean-Stocker tube while reacting for 2 hours. Then heat at 180 °C for 1 hour, removing all the added toluene from the Dean-Stocker tube. After cooling the solution to 50°C, 25g of NMP and 11.704g (40mmol) of 4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) were added. The mixture was stirred at 50°C for 4 hours, cooled to room temperature, and then 27.723g (2mmol) of organosilicon diamine X-22-1660-B-37.723g (2mmol) from Shin-Etsu Chemical Co., Ltd. was added. The mixture was stirred for 1 hour. Then, the solution was added dropwise to 6 times its volume of water while stirring, causing the polymer to precipitate. After filtering out the polymer, it was vacuum dried at 40°C for 24 hours. The polymer was then dissolved in sulfolane at 15wt% to obtain a polyamic acid-soluble polyimide solution. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, yielding results of 2.2%, 1.3%, and 500ppm, respectively.

[0913] [Comparative Example III-11]

[0914] In Example III-19, sulfolane was not added, but otherwise a polyamic acid-soluble polyimide solution was obtained in the same manner as in Example III-19. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.0%, 2.2%, and 0 ppm, respectively.

[0915] [Example III-21]

[0916] The 500ml detachable flask was purged with nitrogen. An amount of freshly opened 18L can of N-methylpyrrolidone (NMP: 250ppm water) as solvent, equivalent to 15wt% of the solid content, was added to the detachable flask. 3.4576g (30.3mmol) of 1,4-cyclohexanediamine (1,4-CHDA) and 26.0326g (70.7mmol) of 4,4'-bis(aminophenoxy)biphenyl (BAPB) were added and stirred until dissolved. Then, 30.5098 g (100.9 mmol) of decahydro-1,4:5,8-dimethylnaphthalene-2,3,6,7-tetracarboxylic acid dianhydride (DNDA) was added. After stirring at room temperature under a nitrogen atmosphere for one night, sulfolane was added in such a way that (mass of solvent + mass of sulfolane) equals 20 wt% when 100 wt%. The mixture was stirred for another hour to obtain a polyamic acid solution (hereinafter also referred to as varnish).

[0917] The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured. The results were 2.1%, 1.8%, and 0 ppm, respectively.

[0918] [Comparative Example III-12]

[0919] In Examples III-21, sulfolane was not added, but otherwise a polyamic acid-soluble polyimide solution was obtained in the same manner as in Examples III-21. The varnish was cured in the same manner as in Example III-1, and the in-plane film thickness uniformity, YI, and degassing amount upon reheating of the polyimide resin film were measured, with results of 12.2%, 2.9%, and 0 ppm, respectively.

[0920] The results of the above embodiments and comparative examples are summarized in Tables 11 to 13.

[0921] [Table 11]

[0922]

[0923] [Table 12]

[0924]

[0925] [Table 13]

[0926]

[0927] As described above, compared with the comparative example, the resin composition of the embodiment is softer, maintains fluidity, and when made into a polyimide resin film, the in-plane uniformity of film thickness is improved and the YI is reduced, resulting in excellent properties required for display applications.

[0928] Explanation of reference numerals in the attached figures

[0929] 2a lower base plate

[0930] 2b Sealed Substrate

[0931] 25 Organic EL Structure

[0932] 250A organic EL element emitting red light

[0933] 250b organic EL element emitting green light

[0934] Organic EL element emitting blue light at 250°C

[0935] 251 partition wall (dam)

[0936] 252 Lower Electrode (Anode)

[0937] 253 Hole Transport Layer

[0938] 254 light-emitting layers

[0939] 255 Upper Electrode (Cathode)

[0940] 256TFT

[0941] 257 contact hole

[0942] 258 interlayer insulation film

[0943] 259 Lower Electrode

[0944] 261 Hollow Section

Claims

1. A resin composition, characterized in that, It comprises: a polyamic acid-imide copolymer containing structural units of the following general formula (1), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is at least one selected from the group consisting of imidazole compounds, pyridine compounds, and tertiary amine compounds, and the polyamic acid-imide copolymer is a block copolymer. In formula (1), X1 and X3 represent tetravalent organic groups derived from aromatic tetracarboxylic acid dianhydrides with 8 to 36 carbon atoms, X2 and X4 represent divalent organic groups, n, m, and l are positive integers, and, As X2 in the general formula (1), it includes the structure shown in the following general formula (A-1). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents a bonding part.

2. The resin composition according to claim 1, wherein, The imidazole compound is at least one selected from the group consisting of 1-methylimidazolium, N-tert-butoxycarbonylimidazolium (N-Boc-imidazolium), 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, 2-ethyl-4-methylimidazolium, 4-ethyl-2-methylimidazolium, 4-methyl-2-phenylimidazolium, 2-undecylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1H-imidazolium, and 1,2-dimethylimidazolium. The pyridine compound is at least one selected from the group consisting of 4-dimethylaminopyridine, 2,2'-bipyridine, nicotinic acid, isoquinoline, pyridine, and 2-methylpyridine, and / or The tertiary amine compound is at least one selected from the group consisting of 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, and triethylamine.

3. The resin composition according to claim 1 or 2, wherein, The imidization catalyst (e) is the imidazole compound.

4. The resin composition according to claim 1 or 2, wherein, The content of the imidization catalyst (e) is 5 parts by mass or more relative to 100 parts by mass of the polyamic acid-imide copolymer.

5. A resin composition comprising: a polyamic acid-imide copolymer containing structural units of the following general formula (1) and (d) an organic solvent, wherein the polyamic acid-imide copolymer has a weight-average molecular weight of 170,000 or more, and the polyamic acid-imide copolymer is a block copolymer. In formula (1), X1 and X3 represent tetravalent organic groups derived from aromatic tetracarboxylic acid dianhydrides with 8 to 36 carbon atoms, X2 and X4 represent divalent organic groups, n, m, and l are positive integers, and, As X2 in the general formula (1), it includes the structure shown in the following general formula (A-1). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents a bonding part.

6. The resin composition according to claim 1 or 2, wherein, The polyamic acid-imide copolymer has a weight-average molecular weight of 170,000 or higher.

7. A resin composition comprising: a polyamic acid containing a structural unit of the following general formula (3), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is selected from 1-methylimidazolium, N-tert-butoxycarbonylimidazolium (N-Boc-imidazolium), 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, 2-ethyl-4-methylimidazolium, 4-ethyl-2-methylimidazolium, 4-methyl-2-phenylimidazolium, 2-decyl... The polyamic acid comprises at least one of the following groups: monoalkyl imidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1H-imidazole, 4-dimethylaminopyridine, 2,2'-bipyridine, nicotinic acid, isoquinoline, pyridine, 2-methylpyridine, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,4-diazabicyclo[2.2.2]octane, N-methylmorpholine, and triethylamine, wherein the polyamic acid has a weight-average molecular weight of 170,000 or more. In formula (3), X1 represents a tetravalent organic group derived from an aromatic tetracarboxylic acid dianhydride with 8 to 36 carbon atoms, X2 represents a divalent organic group, and n is a positive integer. As X2 in the general formula (3), it includes the structure shown in the following general formula (A-1). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents a bonding part.

8. A resin composition comprising: a polyamic acid containing a structural unit of the following general formula (3), (d) an organic solvent, and (e) an imidization catalyst, wherein the (e) imidization catalyst is an imidazole compound, and the content of the (e) imidization catalyst is 5 parts by mass or more relative to 100 parts by mass of the polyamic acid, wherein the polyamic acid has a weight-average molecular weight of 170,000 or more. In formula (3), X1 represents a tetravalent organic group derived from an aromatic tetracarboxylic acid dianhydride with 8 to 36 carbon atoms, X2 represents a divalent organic group, and n is a positive integer. As X2 in the general formula (3), it includes the structure shown in the following general formula (A-1). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * represents a bonding part.

9. The resin composition according to claim 1 or 7, wherein, The content of the imidization catalyst in (e) is 10 parts by mass or more relative to 100 parts by mass of the polyamic acid-imide copolymer or 100 parts by mass of the polyamic acid.

10. The resin composition according to claim 1 or 7, wherein, The (e) imidization catalyst is an imidazole compound comprising N-tert-butoxycarbonyl imidazole (N-Boc-imidazole) and / or 1-methylimidazole.

11. The resin composition according to claim 1 or 7, wherein, The polyamic acid-imide copolymer or the polyamic acid has a weight-average molecular weight of 220,000 or more.

12. The resin composition according to claim 11, wherein, The weight-average molecular weight is a value obtained using gel permeation chromatography in the form of a standard polystyrene equivalent.

13. The resin composition according to claim 1 or 7, further comprising an aprotic polar substance having a boiling point of 250°C to 350°C.

14. The resin composition according to claim 13, wherein, The aprotic polar substance is sulfolane.

15. The resin composition according to claim 1 or 7, wherein, In the general formula (1), X4 or in the general formula (3), X2 is selected from at least one of the following general formulas (A-4), (A-5), and (A-6) which consist of the structures shown below. In formula (A-4), R8~R 11 Each of these groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4. Z2 represents a linking group, and * represents a bonding part. In equation (A-5), R 12 and R 13 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * denotes a bonding part. In equation (A-6), R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and о are each an integer from 0 to 4, and * represents a bonding part.

16. The resin composition according to claim 1, wherein, In the general formula (1), X3 is selected from at least one of the following groups: the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxophthalic dianhydride (ODPA), the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA), the structure derived from biphenyl tetracarboxylic dianhydride (BPDA), and the structure derived from 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ). In formula (A-3), R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part.

17. The resin composition according to claim 1, wherein, The content of the imidization catalyst in (e) is in the range of 0.02 to 0.15 mol% relative to 1 mole of the repeating unit of the polyamic acid-imide copolymer.

18. A polyamic acid-imide copolymer, characterized in that, The polyamic acid-imide copolymer comprises the structural unit L shown in the following general formula (1), wherein the polyamic acid-imide copolymer is a block copolymer. In formula (1), X1 and X3 represent tetravalent organic groups derived from aromatic tetracarboxylic acid dianhydrides with 8 to 36 carbon atoms, X2 and X4 represent divalent organic groups, and n, m, and l are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M. When X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate, it does not include the following components 1 and 2:

1. When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorenic anhydride (BPAF), X4 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and 2. X3 is composed of a group derived from norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2''-norcamphene-5,5'',6,6''-tetracarboxylic acid dianhydride. and, As X2, it has the structure shown in the following general formula (A-1) or the following general formula (A-2). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen having 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * denotes a bonding part. In formula (A-2), R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, and c is an integer from 0 to 4, and * represents the bonding part.

19. The polyamic acid-imide copolymer according to claim 18, wherein, The diamine constituting X2 in the general formula (1) and the diamine constituting X4 do not contain organosilicon diamines.

20. The polyamic acid-imide copolymer according to claim 18, wherein, In the general formula (1), X3 is selected from at least one of the following groups: the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). In formula (A-3), R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part.

21. The polyamic acid-imide copolymer according to any one of claims 18 to 20, wherein, In the general formula (1), X4 is selected from at least one of the following general formulas (A-4), (A-5), and (A-6) structures. In formula (A-4), R8~R 11 Each of these groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4. Z2 represents a linking group, and * represents a bonding part. In equation (A-5), R 12 and R 13 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * denotes a bonding part, except where X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) and the general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone. In equation (A-6), R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and о are each an integer from 0 to 4, and * represents a bonding part.

22. A polyamic acid-imide copolymer, characterized in that, The polyamic acid-imide copolymer comprises the structural unit L shown in the following general formula (1), wherein the polyamic acid-imide copolymer is a block copolymer. In formula (1), X1 and X3 represent tetravalent organic groups derived from aromatic tetracarboxylic acid dianhydrides with 8 to 36 carbon atoms, X2 and X4 represent divalent organic groups, and n, m, and l are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M. X4 does not include groups derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine. and, As X3, it comprises at least one structure selected from the group consisting of the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). In formula (A-3), R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part.

23. The polyamic acid-imide copolymer according to claim 22, wherein, In the general formula (1), X4 is selected from at least one of the following general formulas (A-4), (A-5), and (A-6) structures. In formula (A-4), R8~R 11 Each of these groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4. Z2 represents a linking group, and * represents a bonding part. In equation (A-5), R 12 and R 13 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, i and j are each independently integers from 0 to 4, and * represents a bonding part, except when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) and the general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone. In equation (A-6), R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and о are each an integer from 0 to 4, and * represents a bonding part.

24. The polyamic acid-imide copolymer according to claim 18, wherein, The diamine component constituting X2 in the general formula (1) is not the same as the diamine composition or diamine type constituting X4.

25. The polyamic acid-imide copolymer according to claim 18, wherein, In the general formula (1), X1 is selected from at least one of the following groups: a structure derived from biphenyltetracarboxylic acid dianhydride (BPDA), a structure derived from 4,4'-oxophthalic acid dianhydride (ODPA), and a structure derived from 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ).

26. The polyamic acid-imide copolymer according to claim 18, wherein, The molar ratio (X2 / X1) of X2 in the general formula (1) is 0.84 to 1.00, and the molar ratio (X4 / X3) of X4 in the general formula (1) is 1.01 to 2.

00.

27. The polyamic acid-imide copolymer according to claim 18, wherein, The molar ratio (X2 / X1) of X2 and X1 contained in the general formula (1) is 0.85 to 1.2, and the molar ratio (X4 / X3) of X4 and X3 contained in the general formula (1) is 0.95 to 1.

5.

28. The polyamic acid-imide copolymer according to claim 18, wherein, The molar ratio (X2 / X1) of X2 in the general formula (1) is 0.92 to 1.00, and the molar ratio (X4 / X3) of X4 in the general formula (1) is 1.01 to 1.

25.

29. The polyamic acid-imide copolymer according to claim 18, wherein, The molar ratio (number of moles of structural unit N: number of moles of structural unit M) of polyamic acid composed of X1 and X2 in the general formula (1) is in the range of 60:40 to 95:

5.

30. The polyamic acid-imide copolymer according to claim 29, wherein, The molar ratio (number of moles of structural unit N: number of moles of structural unit M) of polyamic acid composed of X1 and X2 to polyimide composed of X3 and X4 in the general formula (1) is in the range of 60:40 to 80:

20.

31. A resin composition comprising the polyamic acid-imide copolymer of any one of claims 18 to 30 and (d) an organic solvent.

32. The resin composition according to claim 31, wherein, The ratio of polyamic acid structural units N, consisting of X1 and X2, in all polymers contained in the resin composition is 60 to 95 moles.

33. The resin composition according to claim 31 or 32, further comprising (e) an imidization catalyst.

34. A polyimide copolymer, characterized in that, It includes the structural unit shown in the following general formula (2), In equation (2), X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n and m are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M. When X2 is a group derived from 4-amino-3-fluorophenyl-4-aminobenzoate, it does not include the following components 1 and 2:

1. When X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorenidine (BPAF), X4 is a group derived from 4,4'-diaminodiphenyl sulfone and / or 2,2'-bis(trifluoromethyl)benzidine; and 2. X3 is composed of a group derived from norcamphene-2-spiro-α-cyclopentanone-α'-spiro-2''-norcamphene-5,5'',6,6''-tetracarboxylic acid dianhydride. and, As X2, it has the structure shown in the following general formula (A-1) or the following general formula (A-2). In formula (A-1), R1 and R2 each independently represent a monovalent organic group or halogen having 1 to 20 carbon atoms, a and b each independently represent integers from 0 to 4, and * denotes a bonding part. In formula (A-2), R3 represents a monovalent organic group or halogen with 1 to 20 carbon atoms, c is an integer from 0 to 4, and * represents the bonding part. The polyimide copolymer is formed by imidization of the polyamic acid-imide copolymer of claim 18.

35. The polyimide copolymer according to claim 34, wherein, In the general formula (2), X3 is selected from at least one of the following groups: the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). In formula (A-3), R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part.

36. A polyimide copolymer, characterized in that, It includes the structural unit shown in the following general formula (2): In equation (2), X1 and X3 represent tetravalent organic groups, X2 and X4 represent divalent organic groups, and n and m are positive integers. The structural unit composed of X1 and X2 is called structural unit N, and the structural unit composed of X3 and X4 is called structural unit M. X4 does not include groups derived from 4,4'-diaminodiphenyl sulfone or 2,2'-bis(trifluoromethyl)benzidine. and, As X3, it comprises at least one structure selected from the group consisting of the structure shown in the following general formula (A-3), the structure derived from 4,4'-oxyphthalic anhydride (ODPA), and the structure derived from 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA). In formula (A-3), R4 to R7 each independently represent a monovalent organic group or halogen with 1 to 20 carbon atoms, d to g each independently represent an integer from 0 to 4, Z1 represents a linking group, and * represents a bonding part. The polyimide copolymer is formed by imidization of the polyamic acid-imide copolymer of claim 22.

37. The polyimide copolymer according to claim 36, wherein, In the general formula (2), X4 is selected from at least one of the following general formulas (A-4), (A-5), and (A-6) structures. In formula (A-4), R8~R 11 Each of these groups independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, and h to k are each an integer from 0 to 4. Z2 represents a linking group, and * represents a bonding part. In equation (A-5), R 12 and R 13 Each of the following independently represents a monovalent organic group or halogen having 1 to 20 carbon atoms, where l and m are each an integer from 0 to 4, and * denotes a bonding portion, except when X3 is a group derived from 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydric anhydride (BPAF) and the general formula (A-5) is a group derived from 4,4'-diaminodiphenyl sulfone. In equation (A-6), R 14 and R 15 Each of the following independently represents a monovalent organic group or halogen with 1 to 20 carbon atoms, where n and о are each an integer from 0 to 4, and * represents a bonding part.

38. The polyimide copolymer according to any one of claims 34 to 37, wherein, In the general formula (2), X1 is selected from at least one of the following groups: a structure derived from biphenyltetracarboxylic acid dianhydride (BPDA), a structure derived from 4,4'-oxophthalic acid dianhydride (ODPA), and a structure derived from 4,4'-biphenyl bis(triphenylamine monoester anhydride) (TAHQ).

39. The polyimide copolymer according to claim 34, wherein, The molar ratio (X2 / X1) of X2 and X1 contained in the general formula (2) is 0.84 to 1.00, and the molar ratio (X4 / X3) of X4 and X3 contained in the general formula (2) is 1.01 to 2.

00.

40. The polyimide copolymer according to claim 34, wherein, The molar ratio (number of moles of structural unit N: number of moles of structural unit M) of polyimide composed of X1 and X2 in the general formula (2) is in the range of 60:40 to 95:

5.

41. A resin composition, characterized in that, The resin composition comprises a polyimide precursor having the following general formula (I), or a polyimide precursor backbone having the following general formula (I) and a polyimide backbone having the following general formula (II), wherein the resin composition contains an aprotic polar substance having a boiling point of 250°C to 350°C, and wherein the amount of the aprotic polar substance is 5 wt% or more when the sum of the mass of the solvent and the mass of the aprotic polar substance is set to 100 wt%. In formula (I), P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer. In formula (II), P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer. In formulas (I) and (II), P1 contains a structural unit derived from at least one of the diamines represented by the general formulas (3) to (12) below. 。 42. A resin composition comprising a polyimide of general formula (II), a solvent, and an aprotic polar substance having a boiling point of 250°C to 350°C, wherein the amount of the aprotic polar substance is 5 wt% or more when the sum of the mass of the solvent and the mass of the aprotic polar substance is set to 100 wt%. In formula (II), P1 represents a divalent organic group, P2 represents a tetravalent organic group, and p represents a positive integer. In formula (II), P1 contains a structural unit derived from at least one of the diamines represented by the following general formulas (3) to (12). 。

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