Polyamic acid, polyimide, and thin films for forming highly transparent, low dielectric substrates

Abstract

To provide a polyamic acid which enables manufacture of a heat resistant coating, an insulation coating, a coating agent, a thin film, an insulation film, a heat resistant film, a base material for tape automation bonding, a protective film of a semiconductor element, an interlayer insulation film of an integrated circuit, a flexible heat resistant substrate, a flexible insulation substrate, and a wire coating material, a polyimide-based resin composition containing the polyamic acid, and a polyimide film and a substrate which are formed using the composition and are excellent in heat resistance, transparency and low dielectric properties.SOLUTION: A polyamic acid is obtained by reacting a tetracarboxylic acid dianhydride represented by (1) with a raw material containing diamine.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyimide (polyimide resin) having high transparency and low dielectric properties.

[0002] The present invention relates to a polymer made from a tetracarboxylic dianhydride represented by formula (1), a varnish containing the polymer and a solvent, and a heat-resistant paint, insulating paint, coating agent, thin film, insulating film, heat-resistant film, substrate for tape automation bonding, protective film for semiconductor elements, interlayer insulating film for integrated circuits, flexible heat-resistant substrate, flexible insulating substrate, and wire coating material formed from the varnish. [Background technology]

[0003] In the field of displays, such as liquid crystal display elements and organic electroluminescence display elements, inorganic glass is widely used as a transparent substrate that constitutes the panel, but the high specific gravity and brittleness of inorganic glass are problems. Therefore, a transparent material with a low specific gravity that can replace glass is required, but when forming a transparent electrode made of ITO on a transparent substrate, a high temperature of 200°C or more is required to obtain high conductivity, so a material with further heat resistance is required.

[0004] Polyimide resins are known to have high heat resistance among polymer films, and are widely used as electronic materials such as protective materials and insulating materials in display elements and semiconductors. However, aromatic polyimide resin films are generally colored yellow or brown due to the absorption of visible light resulting from the formation of intramolecular or intermolecular charge transfer complexes. For this reason, they are unsuitable for optical applications such as transparent substrate materials for flat panel displays, optical fibers, and optical waveguides.

[0005] Acrylic resins, which have been used as optical plastics, have low birefringence and colorless transparency, but lack heat resistance, making them unusable for the above applications. Polycarbonate has a high glass transition temperature, but does not have satisfactory heat resistance to coloration. As a method for solving such problems, several reports have been made on transparent polyimide films.

[0006] Polyimide resins have also been used in the past for printed wiring boards, interlayer insulating films, etc. The polyimide resins used for these applications are aromatic, and typically, the dielectric constant of these aromatic polyimides is said to be 3.0 to 4.0 (see Non-Patent Document 1).

[0007] However, in recent years, in the development of large-scale integrated circuits (LSIs), wiring has become finer in order to increase the speed of calculations, and although the interlayer insulating films used for these applications require even higher insulation properties, conventional polyimide resins have a high dielectric constant and cannot be used.

[0008] Therefore, studies have been made to reduce the dielectric constant of polyimide resins while maintaining their heat resistance. One of these methods involves the introduction of atoms with low molar polarizability, typically fluorine atoms (see Non-Patent Document 2). However, there are problems with the availability of raw materials and the cost in industrially producing polyimide resins with fluorine atoms introduced.

[0009] In addition, polyimide resins generally have low solubility in solvents. For this reason, they are usually applied as a solution in the form of their precursor, polyamic acid, and then converted to polyimide by heating at high temperatures. This limits processability, and there are problems with its use, particularly when the area where polyimide is to be applied is susceptible to irreversible damage caused by heat. Furthermore, shrinkage usually occurs when the film is cooled after high-temperature treatment, and the thermal stress generated during this process often causes serious problems such as peeling or cracking of the film.

[0010] In light of this situation, several proposals have been made for colorless, transparent, low-dielectric polyimide resins that maintain heat resistance. One of these methods involves producing a polyimide resin using a tetracarboxylic dianhydride or diamine that has an aliphatic group rather than an aromatic ring. For example, a polyimide resin has been proposed that uses a tetracarboxylic dianhydride that has a structure in which alicyclic skeletons are continuously condensed as a raw material (Patent Document 1). However, the birefringence of this polyimide resin is not necessarily sufficient, and the synthesis of the raw material is complicated and involves multiple steps, making industrial production problematic.

[0011] In addition, a polyimide resin made from 1,2,4,5-cyclohexanetetracarboxylic dianhydride has been proposed as a substrate material for thin-film transistors (Patent Document 2). However, according to the examples described therein, although the obtained polyimide resin has high transparency, it is colored light brown, and therefore cannot be used in applications that require high colorless transparency. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2003-96070 A [Patent Document 2] JP 2003-168800 A [Non-patent literature]

[0013] [Non-Patent Document 1] 54th (2005) Polymer Symposium Proceedings 2Pc095 [Non-Patent Document 2] Macromolecules, 27, 5964 (1994). Summary of the Invention [Problem to be solved by the invention]

[0014] The object of the present invention is to provide a polyamic acid capable of producing a heat-resistant paint, an insulating paint, a coating agent, a thin film, an insulating film, a heat-resistant film, a substrate for tape automation bonding, a protective film for a semiconductor element, an interlayer insulating film for an integrated circuit, a flexible heat-resistant substrate, a flexible insulating substrate, and a wire coating material, a polyimide-based resin composition containing the polyamic acid, and a polyimide film or substrate formed using the composition, which has excellent heat resistance, transparency, and low dielectric properties. The polyimide film or substrate obtained by the present invention also has excellent adhesion and flexibility. [Means for solving the problem]

[0015] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that a polyamic acid obtained from a tetracarboxylic dianhydride represented by formula (1) and a diamine has high transparency and low dielectric properties even when heated to 200°C or higher in air during film production, thereby completing the present invention. Examples of aspects of the present invention are shown below. Effect of the Invention

[0016] By using the polyamic acid of the present invention, it is possible to provide polyimide films and substrates having excellent transparency and low dielectric properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention includes the following items. [1] A polyamic acid obtained by reacting a raw material containing a tetracarboxylic dianhydride represented by formula (1) with a diamine. TIFF0007658242000001.tif2454

[0018] [2] The polyamic acid according to item [1], wherein the diamine has an aromatic ring.

[0019] [3] The polyamic acid according to item [2], wherein the diamine is at least one selected from the group of compounds represented by formulae (A-1) to (A-3): TIFF0007658242000002.tif52107 In the formulae (A-1) to (A-3), at least one hydrogen atom on the benzene ring of the compound may be replaced by methyl, and X and Y are independently a single bond, —O—, —N═N—, —CO—, —S—, or —SO 2 -, branched alkylene having 2 to 6 carbon atoms, or linear alkylene having 1 to 6 carbon atoms.

[0020] [4] The polyamic acid according to any one of items [1] to [3], wherein the raw material further contains at least one acid component selected from the group consisting of the following (a) to (c): (a) a dianhydride or a dicarboxylic acid monoanhydride corresponding to a tetracarboxylic acid represented by any one of formulas (2) to (12); TIFF0007658242000003.tif110169 (b) a tricarboxylic acid selected from the group consisting of 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,3-cyclohexanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,3-cyclopentanetricarboxylic acid, and 1,2,4-cyclopentanetricarboxylic acid, or the corresponding carboxylic acid monoanhydride; (c) a dicarboxylic acid represented by formula (13) or the corresponding monoanhydride; TIFF0007658242000004.tif1649 In formula (13), Z is 1,2-phenylene, 1,2-naphthyl, 2,3-naphthyl, ethylene, propylene, or 1,2-cyclohexylene, and at least one hydrogen on the aromatic ring of these groups may be replaced by methyl, ethyl, or phenyl.

[0021] [5] A polyimide obtained by a dehydration reaction of the polyamic acid according to any one of items [1] to [4].

[0022] [6] A varnish containing the polyamic acid according to any one of items [1] to [4] and a solvent.

[0023] [7] A varnish comprising the polyamic acid according to any one of items [1] to [4], a polyimide derived from the polyamic acid, and a solvent.

[0024] [8] A thin film formed from the varnish according to item [6] or [7].

[0025] [9] The polyimide according to item [5] or the thin film according to item [8], having a transmittance of 60% or more at 400 nm.

[0026]

[10] The polyimide according to item [5] or the thin film according to item [8], having a dielectric constant of 3.3 or less.

[0027]

[11] A heat-resistant paint, insulating paint, or coating agent formed from a varnish according to paragraph [6] or [7].

[0028]

[12] An insulating film, a heat-resistant film, a substrate for tape automation bonding, a protective film for a semiconductor element, or an interlayer insulating film for an integrated circuit, formed from the thin film according to item [8].

[0029] The polyamic acid, resin solution composition, polyimide resin, polyimide film, and uses thereof according to the present invention will be described in detail below. <Varnish (resin solution composition)> The varnish of the present invention is a resin solution composition containing a polyamic acid or polyimide resin obtained by reacting a compound represented by formula (1) (hereinafter also referred to as "compound (1)") with a diamine.

[0030] <Diamine> Diamines include 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 3,5-diaminobenzotrifluoride, 2,5-diaminobenzotrifluoride, 3,5-diamino-1,6-dimethoxybenzene, 3,5-diamino-1,6-dimethoxytoluene, 4,4'-binaphthylamine, 4,4'-diaminobenzanilide, 1,5-diamino Naphthalene, diaminonaphthalene, benzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, diphenyl-4,4'-diaminodiphenyl, dimethyl-4,4'-diaminodiphenyl Phenyl, dialkyl-4,4'-diaminodiphenyl, dimethoxy-4,4'-diaminodiphenyl, diethoxy-4,4'-diaminodiphenyl, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-methylaniline), 4,4'-methylenebis(2- ethylaniline), 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-methylenebis(2,6-diethylaniline), 2,2-diaminodiphenylpropane, bis(3,5-diethyl-4-aminophenyl)methane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,4'-Diaminodiphenyl sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 2,4'-diaminodiphenyl sulfide, 4,4'-bis(4-aminophenyl)sulfide, 4,4'-benzophenonediamine, 3,3'-benzophenonediamine, 9, 10-bis(4-aminophenyl)anthracene, 1,4-bis(4-aminophenyl)benzene, 1,4-terphenylenediamine, 1,1,1,3,3,3-hexafluoro-2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(4-(3-aminophenoxy)phenyl)propane, bis(4-aminophenoxy)pentane, 1,3-bis(4-amino-3-methylphenoxy)benzene, 1,3-bis(4-aminophenoxy)phenyl 1,3-bis(4-aminophenoxy)-5-methylbenzene, 1,3-bis(4-aminophenoxy)-5-decylbenzene, 1,3-bis(4-aminophenoxy)-5-eicosylbenzene, 1,3-bis(4-amino-3-dodecylphenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)-5-cyanobenzene, 1,3-bis(4-aminophenoxy)-5-chlorobenzene, 1,3-bis(4-aminophenoxy) -5-Methoxybenzene, 1,3-bis(4-aminophenoxy)-5-vinylbenzene, 1,3-bis(4-aminophenoxy)-5-allylbenzene, 1,3-bis(4-aminophenoxy)-5-carboxybenzene, 1,3-bis(4-aminophenoxy)-5-cyclopropylbenzene, 1,3-bis(4-aminophenoxy)-5-cyclohexylbenzene, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-amino-4-methylphenoxy)benzene, 1,3-bis(3-aminophenoxy)-5-methylbenzene, 1,3-bis(3-aminophenoxy)-5-decylbenzene, 1,3-bis(3-aminophenoxy)-5-eicosylbenzene, 1,3-bis(3-amino-4-dodecylphenoxy)benzene, 1,3-bis(3-aminophenoxy)-5-cyanobenzene, 1,3-bis(3-aminophenoxy)-5-chlorobenzene, 1,3-bis(3-aminophenoxy)-5-methoxybenzene, 1,3-bis(3-aminophenoxy)-5-vinylbenzene, 1,3-bis(3-aminophenoxy)-5-allylbenzene, 1,3-bis(3-aminophenoxy)-5-allylbenzene, 1,3-bis(3-aminophenoxy)-5-carboxybenzene, 1,3-bis(3-aminophenoxy)-5-cyclopropylbenzene, 1,3-bis(3-aminophenoxy)-5-cyclohexylbenzene, 4,4'-bis(4-aminophenoxy)biphenyl, 3,7-diamino-dimethyldibenzothiophene-5,5-dioxide, 1,3-bis(4-aminophenoxy)propane, 1,4-bis(4-aminophenoxy)butane, 1,5-bis(4-aminophenoxy)pentane, 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, 1,2-bis[2-( 4-aminophenoxy)ethoxy]ethane, 9,9-bis(4-aminophenyl)fluorene, 5(6)-amino-1-(4-aminomethyl)-1,3,3-trimethylindane, 1,2-tolidine, 1,3-tolidine, 2,2'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 3,3'-bistrifluoromethyl-4,4'-diaminobiphenyl, 3,3'-bistrifluoromethyl-5,5'-diaminobiphenyl, bis(trifluoromethyl)-4,4'-diaminodiphenyl phenyl, bis(fluorinated alkyl)-4,4'-diaminodiphenyl, bis(fluorinated alkoxy)-4,4'-diaminodiphenyl, 4,4'-bis(4-aminotetrafluorophenoxy)tetrafluorobenzene, 4,4'-bis(4-aminotetrafluorophenoxy)octafluorobiphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-(3-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-(4-amino-2-trifluoromethylphenoxy)phenyl)hexafluoropropane, 2,2-bis(4-(3-amino-5-trifluoromethylphenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 4,4'-bis(4-aminophenoxy)octafluorobiphenyl, 2,2'-trifluoromethyl-4,4'-diaminobiphenyl, dichloro-4,4'-diaminodiphenyl, dibromo-4,4'-diaminodiphenyl, 2,6-diaminopyridine, 2,4-diaminopyridine, 2,4-diamino-s-triazine, 2,7-diaminobenzofuran, 2,7-diaminocarbazole, 3,4-diaminopyridine, 4,4-diamino-s-triazine ... ,7-Diaminophenothiazine, 2,5-Diamino-1,3,4-thiadiazole, 2,4-Diamino-6-phenyl-s-triazine, 4-Aminobenzoic acid-4-aminophenyl ester, 2-(4-aminophenyl)aminobenzoxazole, 5,5'-methylene-bis-(anthranilic acid), 3,5-Diaminobenzoic acid, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl-6,6'-disulfonic acid, 4,4'-bis(4 -aminophenoxy)biphenyl-3,3'-disulfonic acid, 4,4'-bis(3-aminophenoxy)biphenyl, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 4,6-dihydroxy-1,3-phenylenediamine, 3,3',4,4'-tetraaminobiphenyl, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 2,2'-bis(3-sulfopropoxy)-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and the like.

[0031] <Acid components (a) to (c), etc.> When obtaining the polyamic acid or polyimide of the present invention, other acid dianhydrides or tetracarboxylic acids may be mixed in addition to the tetracarboxylic acid compound of the present invention and copolymerized with diamine. In this case, the acid dianhydrides that can be used are not particularly limited, but examples thereof include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4 ,5,8-Naphthalenetetracarboxylic dianhydride, 2,3,6,7-Naphthalenetetracarboxylic dianhydride, 2,3,6,7-Anthracenetetracarboxylic dianhydride, 1,2,5,6-Anthracenetetracarboxylic dianhydride, Bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-Bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-Bis(2,3-dicarboxyphenyl)propane dianhydride, 3,3' ,4,4'-Benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-oxydiphthalic anhydride, bis(2,3-dicarboxyphen Examples include bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)hexafluoropropane dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride.

[0032] On the other hand, examples of alicyclic acid anhydrides that can be used in addition include cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride, cyclohexyl tetracarboxylic acid dianhydride, 3,3',4,4'-bicyclohexyl tetracarboxylic acid dianhydride, 1,2,3,4-butane tetracarboxylic acid dianhydride, ethylene tetracarboxylic acid dianhydride, 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic acid dianhydride, 1,2,4,5-cyclopentane tetracarboxylic acid dianhydride, 1,2,3,4-cyclopentane tetracarboxylic acid dianhydride, 1,2,4,5-cyclohexane tetracarboxylic acid dianhydride, and the like. Examples of the dianhydride include tetracarboxylic dianhydrides having an alicyclic structure, such as 2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalenesuccinic dianhydride, bicyclo[3,3,0]octane-2,4,6,8-tetracarboxylic dianhydride, 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic-2,6:3,5-dioic anhydride, and 4-phenylethynylphthalic anhydride.

[0033] The ratio of the acid dianhydride to the tetracarboxylic acid compound of the present invention used can be set arbitrarily depending on the physical properties of the resin to be obtained, but the amount of the compound (1) of the present invention used is preferably 30 mol % or more, more preferably 50 mol % or more, and is preferably 99 mol % or less, and more preferably 90 mol % or less.

[0034] <Additives> The resin solution composition containing the polyamic acid of the present invention may contain other additives to improve properties such as surface smoothness, within a range that does not impair the effects of the present invention. Examples of such additives include polymer compounds, epoxy compounds, acrylic resins, surfactants, antistatic agents, coupling agents, epoxy curing agents, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, reduction inhibitors, evaporation promoters, chelating agents, and water-soluble polymers.

[0035] <Solvent> The solvent used for the varnish is preferably an organic polar solvent. The organic polar solvent is not particularly limited, but examples thereof include γ-butyrolactone, N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, dimethylsulfoxide, hexamethylphosphoramide, p-chlorophenol, m-cresol, tetramethylenesulfone, and propylene carbonate. Two or more of these solvents may be mixed and used. In addition, cyclic ethers such as tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane, chain ethers such as diethylene glycol methyl ethyl ether, and cyclic ketones such as cyclohexanone and cyclopentanone may be used in combination, as long as the solubility of the resulting resin is not reduced. In addition, in order to improve the uniformity of the coating film, solvents having low surface tension such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, methyl lactic acid ester, ethyl lactic acid ester, n-propyl lactic acid ester, n-butyl lactic acid ester, and isoamyl lactic acid ester can also be used. These solvents may be used alone or in combination.

[0036] <Method of producing polyamic acid> The polyamic acid contains, as raw materials, a tetracarboxylic dianhydride represented by formula (1) and a diamine. The method for producing the polyamic acid from these raw materials is not particularly limited, but may be, for example, a method in which the diamine is dissolved in a solvent, and then an acid anhydride is added at about 5°C to room temperature, followed by stirring at about room temperature to 160°C for 30 to 120 minutes, and then further stirring at about room temperature for 60 minutes.

[0037] <Polyimide> The polyimide resin can be obtained by heating the polyamic acid in a solution to imidize it. The method for producing the polyimide resin in the reaction system is not particularly limited, but for example, a method of dissolving a diamine in a solvent, adding compound (1), and refluxing the resulting solution for 4 hours can be used. The solvent can be the same as that used in the production method of polyamic acid.

[0038] Since the polyimide resin of the present invention has excellent heat resistance and transparency, it is suitable for optical applications such as transparent substrate materials for flat panel displays and mobile telephone devices, optical fibers, optical waveguides, and optical adhesives.

[0039] <Film> The method for producing the polyimide film of the present invention is preferably a method including a step of applying the resin solution composition of the present invention onto a substrate and removing the solvent in the coating film by evaporation in air. A preferred embodiment of this method will be described below, but the method for producing the polyimide film of the present invention is not limited to this method.

[0040] The substrate to which the resin solution composition of the present invention is applied is not particularly limited, but examples thereof include inorganic material substrates such as aluminum substrates, glass substrates, and stainless steel substrates, and organic material substrates such as polyimide. The method for applying the resin solution composition of the present invention is not particularly limited, but examples thereof include a method of casting the composition on a substrate using an applicator or spin coater.

[0041] After forming a coating film on the substrate, the coating is pre-dried on a hot plate or in a drying oven at a temperature of 60 to 120°C for about 1 to 60 minutes. Then, the coating is heat-treated at a temperature of 150 to 250°C for about 20 to 120 minutes using a heat circulation oven to obtain a polyimide film. EXAMPLES

[0042] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way. (1) Abbreviations for the names of raw materials and solvents The abbreviations for the names of raw materials and solvents used in the examples and comparative examples are shown below.

[0043] <Tetracarboxylic acid dianhydride> OH-NTCDA: 1,2,3,4,5,6,7,8-octahydro-2,3,6,7-naphthalenetetracarboxylic acid 2,3:6,7-dianhydride PMDA: Pyromellitic dianhydride CMDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride <Diamine> DDM: 4,4'-diaminodiphenylmethane <Solvent> NMP: N-methyl-2-pyrrolidone

[0044] Synthesis Examples, Examples and Comparative Examples <Example 1> A magnetic stirrer was placed in a 100 mL reaction vessel, and 5.5 g of OH-NTCDA, 1.1 g of PMDA, 5.0 g of DDM, and 40 g of NMP were charged and stirred at room temperature for 90 minutes using a magnetic stirrer. Then, 25 g of NMP was added and stirred at room temperature for an additional 60 minutes to obtain a pale yellow 18% (w / w) NMP solution of polyamic acid.

[0045] <Comparative Example 1> A magnetic stirrer was placed in a 100 mL reaction vessel, and 4.0 g of MMDA, 1.1 g of PMDA, 5.0 g of DDM, and 40 g of NMP were charged and stirred at room temperature for 90 minutes using a magnetic stirrer. Then, 25 g of NMP was added, and the mixture was stirred at room temperature for an additional 60 minutes to obtain a pale yellow 16% (w / w) NMP solution of polyamic acid.

[0046] <Comparative Example 2> A magnetic stirrer was placed in a 100 mL reaction vessel, and 5.5 g of PMDA, 5.0 g of DDM, and 40 g of NMP were added and stirred at room temperature for 90 minutes using a magnetic stirrer. Then, 25 g of NMP was added and stirred at room temperature for an additional 60 minutes to obtain a pale yellow 16% (w / w) NMP solution of polyamic acid.

[0047] (2) Evaluation method The preparation of films from each polyamic acid solution and the evaluation of their physical properties were carried out by the methods described below. <Adhesion and flexibility evaluation> The polyamic acid solutions prepared in the Examples and Comparative Examples were applied onto an aluminum foil having a thickness of 0.1 mm, and then baked at 220° C. for 40 minutes to obtain a polyimide film. This film was wrapped around a round bar having a diameter of 5 mm or 1 mm, and the presence or absence of cracks or peeling was confirmed.

[0048] <Thermoplasticity evaluation> The polyimide film prepared in the same manner as in the evaluation of adhesion and flexibility was placed on a hot plate and reheated to evaluate its thermoplasticity.

[0049] <Solubility evaluation> Similarly to the evaluation of adhesion and flexibility, individual pieces of the polyimide prepared were immersed in NMP and stirred with a stirrer to confirm the solubility.

[0050] <Transmittance> The transmittance at 400 nm of the polyimide film (thickness 10 μm) prepared in the same manner as in the evaluation of adhesion and flexibility was measured using a spectrophotometer "V-660" manufactured by JASCO Corporation.

[0051] <Dielectric constant and dielectric loss tangent> The polyamic acid solutions prepared in the examples and comparative examples were applied onto Kapton 300H (manufactured by DuPont-Toray Co., Ltd.; registered trademark) (75 μm), dried at 120° C. for 30 minutes, and then baked in air at 220° C. for 40 minutes to form a 60 μm film. A sample cut into a 50 mm square from this film was measured for the shift and attenuation of the resonance frequency using a cavity resonator (TE mode 10 GHz) manufactured by AET Co., Ltd. connected to a vector network analyzer (Anritsu MS46522B-043), and the relative dielectric constant was calculated using the company's software. In addition, since the measured values ​​were for a two-layer structure consisting of Kapton 300H and a newly applied and cured cured film, the dielectric constant of the cured film alone was calculated using the company's calculation sheet using the values ​​measured for the polyimide film alone. In order to reduce the effect of the moisture content in the strips when comparing data, the strips were formed the day before the measurement, and the evaluation of the dielectric constant was started after leaving the samples to stand for more than 60 minutes in a laboratory with an air conditioner at 20°C.

[0052] Table 1. Evaluation results 1 TIFF0007658242000005.tif41136

[0053] Table 2. Evaluation results 2 TIFF0007658242000006.tif47147

[0054] In Comparative Example 2, since a film could not be formed, evaluation was impossible. It was found that Example 1 was a polyamic acid having superior performance, with higher plasticity and solubility, lower relative dielectric constant and dielectric loss tangent than Comparative Example 1. [Industrial Applicability]

[0055] By using the polyamic acid of the present invention, it is possible to provide a polyimide-based resin composition that can be used to produce a heat-resistant paint, an insulating paint, a coating agent, a thin film, an insulating film, a heat-resistant film, a substrate for tape automation bonding, a protective film for a semiconductor element, an interlayer insulating film for an integrated circuit, a flexible heat-resistant substrate, a flexible insulating substrate, and a wire coating material, as well as a polyimide film or substrate that is formed using the composition and has excellent heat resistance, transparency, and low dielectric properties.

Claims

1. A polyamic acid obtained by reacting a raw material containing a tetracarboxylic dianhydride represented by formula (1) with a diamine.

2. The polyamic acid according to claim 1 , wherein the diamine has an aromatic ring.

3. 3. The polyamic acid according to claim 2, wherein the diamine is at least one selected from the group of compounds represented by formulas (A-1) to (A-3). In the formulae (A-1) to (A-3), at least one hydrogen atom on the benzene ring of the compound may be replaced by methyl, and X and Y each independently represent a single bond, —O—, —N═N—, —CO—, —S—, or —SO ２ -, branched alkylene having 2 to 6 carbon atoms, or linear alkylene having 1 to 6 carbon atoms.

4. The polyamic acid according to any one of claims 1 to 3, wherein the raw material further contains at least one acid component selected from the group consisting of the following (a) to (c): (a) a dianhydride or a dicarboxylic acid monoanhydride corresponding to a tetracarboxylic acid represented by any one of formulas (2) to (12); (b) a tricarboxylic acid selected from the group consisting of 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,3-cyclohexanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,3-cyclopentanetricarboxylic acid, and 1,2,4-cyclopentanetricarboxylic acid, or a corresponding carboxylic acid monoanhydride; (c) a dicarboxylic acid represented by formula (13) or the corresponding monoanhydride; In formula (13), Z is 1,2-phenylene, 1,2-naphthyl, 2,3-naphthyl, ethylene, propylene, or 1,2-cyclohexylene, and at least one hydrogen atom on the aromatic ring of these groups may be replaced by methyl, ethyl, or phenyl.

5. A polyimide obtained by a dehydration reaction of the polyamic acid according to any one of claims 1 to 4.

6. A varnish comprising the polyamic acid according to any one of claims 1 to 4 and a solvent.

7. A varnish comprising the polyamic acid according to any one of claims 1 to 4, a polyimide derived from the polyamic acid, and a solvent.

8. A thin film formed from the varnish according to claim 6 or 7.

9. The polyimide according to claim 5 or the thin film according to claim 8, which has a transmittance of 60% or more at 400 nm.

10. The polyimide according to claim 5 or the thin film according to claim 8, which has a dielectric constant of 3.3 or less.

11. A heat-resistant paint, insulating paint, or coating agent formed from the varnish according to claim 6 or 7.

12. 9. An insulating film, a heat-resistant film, a substrate for tape automation bonding, a protective film for a semiconductor element, or an interlayer insulating film for an integrated circuit, which is formed from the thin film according to claim 8.

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