Polyamic acid composition, and polyimide film

Abstract

To provide a colored or black-colored polyamic acid composition, and a polyimide film having light absorption property of a long wave length side, capable of contributing to development of a carbon neutral and sustainable product, and high in safety.SOLUTION: A polyamic acid composition includes: (a) a polyamic acid having an acid anhydride residue derived from a tetracarboxylic dianhydride constituent, and a diamine residue derived from a diamine constituent; and (b) an organic solvent which includes dihydro-levoglucosenone. A polyimide film of the polyamic acid composition is also provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polyamic acid composition and a polyimide film obtained by imidizing the polyamic acid composition.

Background Art

[0002] In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, there has been an increasing demand for flexible printed circuit boards (FPCs) that are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Since FPCs enable three-dimensional and high-density mounting even in limited space, their applications are expanding, for example, to the wiring of movable parts of electronic devices such as HDDs, DVDs, and smartphones, and to components such as cables and connectors. Many FPCs are manufactured by forming a circuit on the metal layer of a metal-clad laminate obtained by laminating a metal layer using a metal foil or the like and an insulating resin substrate (insulating resin layer).

[0003] By the way, in electronic devices using FPCs, reflected light from the surface of the coverlay film for protecting the wiring portion of the FPC or transmitted light through the FPC may adversely affect the performance of the electronic devices. Therefore, there are cases where the FPC or the coverlay film is required to have light-shielding properties. In addition, when identifying a plurality of wirings inside an electronic device or when the housing of the electronic device is transparent, it is convenient to color the FPC or the coverlay film, and there are cases where design properties are required.

[0004] Conventionally, polyimide films having both heat resistance and insulation properties have been preferably used for the insulating resin layer and the coverlay film in FPCs. And in order to impart light-shielding properties and design properties to the polyimide film, it has been carried out to contain pigments and the like.

[0005] For example, in Patent Document 1, a novel anthraquinone derivative tetraamine monomer with a high molar extinction coefficient is mixed with a diamine monomer and reacted with an acid anhydride monomer to obtain a black polyamic acid solution and a true black polyimide obtained by imidizing it. Further, in Patent Document 2, a black heat-resistant light-shielding film using a black resin film containing a black pigment or the like in a heat-resistant resin such as polyimide, and an optical member obtained by processing the same have been proposed. Furthermore, in Patent Document 3, a single-layer polymer film containing polyimide, a matting agent, and a black coloring agent has been proposed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, since the anthraquinone derivative tetraamine monomer as described in Patent Document 1 has a complex structure, its synthetic route is complex, and adopting it as a monomer of polyimide will lead to high costs. Further, in the methods using black pigments and black colorants such as carbon black as described in Patent Documents 2 and 3, additional steps such as a dispersion step are required to disperse these in the resin, and it is necessary to use an apparatus such as a high-shear rotor-stator mixer, which leads to an increase in cost and a risk of poor quality. Furthermore, in the method of incorporating such a polyimide monomer and black pigment or black colorant into polyimide, the originally required polyimide monomer is relatively reduced, and further, since the content of the resin component itself is relatively reduced, there is a risk that the flexibility and toughness of the resin cured film will decrease. There is also concern that it will significantly affect properties such as the heat resistance and insulation properties that polyimide originally has. Therefore, the methods as described in Patent Documents 1 to 3 are hardly practical methods for imparting light-shielding properties and design properties to polyimide.

[0008] By the way, in recent years, against the backdrop of problems such as global warming and depletion of oil resources, the demand for environmentally friendly materials using bio-based raw materials such as plants has been increasing globally. The use of bio-based raw materials can significantly contribute to carbon neutrality in terms of reducing the use of fossil resources such as oil, and can also contribute to the formation of a sustainable society. Among them, the demand for sustainable product development is also increasing.

[0009] Considering that solvents account for the majority of waste in the organic synthesis of chemical substances, the reduction of their selection and usage amount is an important issue. Regarding this point, for organic solvents such as N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylacetamide (DMAc) that have been conventionally used in the production of polyimide, although the safety during production and use has been fully noted so far, further measures such as minimizing their use are required for further improvement of safety.

[0010] However, in the development of insulating resin layers and polyimide as coverlay films, especially in FPCs, sufficient consideration has not been given to such points.

[0011] Therefore, as a result of the inventors of the present application earnestly studying such problems, quite unexpectedly, it has been found that by using dihydrolevoglucosenone (trademark: Cyrene) obtained from bio-based raw materials as an organic solvent for preparing a composition of polyamic acid which is a precursor of polyimide and the polyimide obtained therefrom, the problem can be solved. That is, by using dihydrolevoglucosenone as an organic solvent, it is possible to impart light absorption characteristics on the long wavelength side to the resulting composition of polyamic acid and polyimide without using polyimide monomers having a complex structure, black pigments, black colorants, etc. That is, it has been found that a composition of polyamic acid and a polyimide film which are colored or blackened can be obtained, and the present invention has been completed.

[0012] Accordingly, an object of the present invention is to provide a composition of polyamic acid and a polyimide film which are colored or blackened and have light absorption characteristics on the long wavelength side without using polyimide monomers having a complex structure, black pigments, black colorants, etc. Another object of the present invention is to provide a composition of polyamic acid and a polyimide film which can contribute to the development of carbon neutral and sustainable products and have high safety.

[0013] In the prior art, a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor and a polyimide and dihydrolevoglucosenone (Cyrene) as a solvent component has been proposed (Patent Document 4). However, it merely discloses the use, and actually, it teaches to improve the coatability by using dihydrolevoglucosenone (Cyrene) as a solvent for dissolving polyimide powder (soluble polyimide). Therefore, for this use, an alicyclic acid anhydride is preferably used as the polyimide monomer, and it is understood that those with relatively few aromatic groups are preferred. Thus, imparting light absorption characteristics on the long-wavelength side, coloring, or the development of blackening, such as those that are problems of the present invention, could not be expected. And Patent Document 4 has no teaching regarding such characteristics that are problems of the present invention.

Means for Solving the Problems

[0014] That is, the present invention is as follows. [1] The following components (a) and (b); (a) A polyamic acid having an acid anhydride residue derived from a tetracarboxylic dianhydride component and a diamine residue derived from a diamine component, (b) An organic solvent, A polyamic acid composition containing, Component (b) is characterized by containing dihydrolevoglucosenone. [2] In component (a), the total of the aromatic acid dianhydride residue derived from an aromatic tetracarboxylic dianhydride component and the aromatic diamine residue derived from an aromatic diamine component is more than 50 mol% in the acid anhydride residue and the diamine residue. The polyamic acid composition according to [1]. [3] Component (b) is characterized by containing 60% by mass or more of a polar aprotic organic solvent. The polyamic acid composition according to [1]. [4] Component (b) is characterized by containing 10% by mass or more of dihydrolevoglucosenone. The polyamic acid composition according to [1]. The polyamic acid composition according to [1], characterized in that the solid content concentration of the component [5] (a) is in the range of 7 to 20% by mass. [6] The light transmittance at 500 nm is 90% or less, and the lightness L * is 95 or less, which is the polyamic acid composition according to [1]. [7] A polyimide film obtained by imidizing the polyamic acid composition according to any one of [1] to [6], at a film thickness of 5 to 15 μm, the light transmittance at 500 nm is 80% or less, and the lightness L * is 90 or less, which is a polyimide film. [8] The total of the aromatic dianhydride residue derived from the aromatic tetracarboxylic dianhydride component and the aromatic diamine residue derived from the aromatic diamine component exceeds 50 mol% in the acid anhydride residue and the diamine residue, which is the polyimide film according to [7].

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a colored or blackened polyamic acid composition and a polyimide film having light absorption characteristics on the long wavelength side without using a polyimide monomer having a complex structure, a black pigment, a black colorant, etc. The polyamic acid composition and the polyimide film according to the present invention are manufactured using an organic solvent obtained from bio-based raw materials, so that they can contribute to carbon neutral and sustainable product development and have high safety.

Brief Description of the Drawings

[0016]

Figure 1

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described.

[0018] [Polyamic Acid Composition] As described above, the polyamic acid composition of the present invention contains (a) a polyamic acid having an acid anhydride residue derived from a tetracarboxylic dianhydride component and a diamine residue derived from a diamine component, and (b) an organic solvent. Hereinafter, the former may be simply referred to as "(a) polyamic acid" or "(a) component". Also, the latter may be referred to as "(b) component". The (a) component and the (b) component will be specifically described.

[0019] <(a) polyamic acid> The (a) polyamic acid used in the present invention is a precursor of polyimide, and is composed of an acid anhydride residue which is a tetravalent group derived from a tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid anhydride") component, and a diamine residue which is a divalent group derived from a diamine compound (hereinafter sometimes simply referred to as "diamine") component. When these constituent components are connected and regarded as one repeating unit, it is composed of a polymer of the repeating unit. The structure can be controlled by adjusting the charged amounts (molar ratio) of the acid anhydride component and the diamine component. The preferred charged amount (molar ratio), as the acid anhydride component / diamine component (molar ratio), is preferably 0.990 to 1.01, more preferably 0.995 to 1.005.

[0020] In the synthesis of the (a) polyamic acid, only one kind of the acid anhydride component and the diamine component may be used respectively, or two or more kinds may be used in combination. By selecting the types of the acid anhydride component and the diamine component, and the respective molar ratios in the case of using two or more kinds of acid anhydride components or diamine components, for example, physical properties such as the optical properties, thermal conductivity, thermal expansion, adhesiveness, glass transition temperature, tear propagation resistance, end crack resistance, and tensile elongation of the polyimide can be controlled.

[0021] In addition, for the (a) polyamic acid used in the present invention, a terminal capping agent may be used. As the terminal capping agent, monoamines or dicarboxylic acids are preferred. The charged amount of the introduced terminal capping agent is preferably in the range of 0.0001 mol or more and 0.1 mol or less, particularly preferably in the range of 0.001 mol or more and 0.05 mol or less, per 1 mol of the acid anhydride component. Examples of the monoamine terminal capping agent include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, aniline, 4-methylaniline, etc. Among these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal capping agent, dicarboxylic acids are preferred, and a part of them may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. are recommended. Among these, phthalic acid and phthalic anhydride can be preferably used.

[0022] In addition, although there is no limitation, the (a) polyamic acid preferably has a viscosity in the range of 100 to 100,000 cP by adjusting the concentration and the weight average molecular weight Mw. A more preferable viscosity is 1,000 to 50,000. When the viscosity is high, it may be diluted by adding a solvent. The weight average molecular weight Mw is preferably in the range of, for example, 1,000 or more and 500,000 or less, more preferably in the range of 5,000 or more and 500,000 or less. When the weight average molecular weight is less than 1,000, the strength of the obtained polyimide film tends to decrease and it tends to become brittle. On the other hand, when the weight average molecular weight exceeds 500,000, the viscosity increases excessively and uneven thickness, streaks, etc. tend to occur easily during the coating operation.

[0023] (Acid anhydride component) Here, as the acid anhydride component used in the present invention, known ones generally used for the synthesis of polyamic acid and polyimide can be used without limitation, but aromatic tetracarboxylic dianhydride is preferred. Further, anhydrides of tetracarboxylic acids having an aliphatic skeleton may be used. For example, aliphatic chain-like tetracarboxylic dianhydrides such as ethylene tetracarboxylic dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride, or anhydrides of alicyclic tetracarboxylic acids may be used. For example, alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, fluorenylidene bisanhydrophthalic acid, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and cyclopentanone bisspironorbornane tetracarboxylic dianhydride can be mentioned.

[0024] Examples of the aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), p-phenylenebis(trimellitate anhydride), 4,4'-oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4'-(paraphenylenedicarbonyl)diphthalic anhydride, 4,4'-(metaphenylenedicarbonyl)diphthalic anhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxydiphenyl ether dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}diphenyl ether dianhydride, bis{3,5-di(trifluoromethyl)phenoxy}pyromellitic dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}benzene dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}, bis(dicarboxyphenoxy)trifluoromethylbenzene dianhydride, bis(dicarboxyphenoxy)bis(trifluoromethyl)benzene dianhydride, bis(dicarboxyphenoxy)tetrakis(trifluoromethyl)benzene dianhydride, 2,2-bis{(4-(3,4-dicarboxyphenoxy)phenyl}hexafluoropropane dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}biphenyl dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}bis(trifluoromethyl)biphenyl dianhydride, bis(dicarboxyphenoxy)bis(trifluoromethyl)biphenyl dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3'',4,4''-p-terphenyltetracarboxylic dianhydride, 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,3,3'',4''-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-diphenylsulfonetetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfonetetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, (trifluoromethyl)pyromellitic dianhydride, di(trifluoromethyl)pyromellitic dianhydride, di(heptafluoropropyl)pyromellitic dianhydride, pentafluoroethylpyromellitic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybiphenyl dianhydride, 2,2',5,5'-tetrakis(trifluoromethyl)-3,3',4,4'-tetracarboxybiphenyl dianhydride, 5,Examples include 5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybenzophenone dianhydride, trifluoromethylbenzene dianhydride, etc.,

[0025] (Diamine component) As the diamine component used in the present invention, generally known ones used in the synthesis of polyamic acid and polyimide can be used without limitation, but aromatic diamine compounds are preferred. Also, diamine compounds having an aliphatic skeleton may be used., For example, 4,4'-diaminodiphenyl ether (4,4’-DAPE), 3,4’-diaminodiphenyl ether, bis(p-β-amino-t-butylphenyl) ether, 1,3-bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene (TPE-Q), bis[4-(4-aminophenoxy)phenyl] ether, 3,4’-diaminodiphenylmethane, 3,4’-diaminodiphenylpropane, 3,4’-diaminodiphenyl sulfide, 3,4’-diaminobenzophenone, (3,3’-bisamino)diphenylamine, 3-[4-(4-aminophenoxy)phenoxy]benzeneamine, 3-[3-(4-aminophenoxy)phenoxy]benzeneamine, 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benz anilide, 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4’-[oxybis(3,1-phenyleneoxy)]bisaniline, bis[4-(4-aminophenoxy)phenyl] ketone (BAPK), bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, 2,2-bis(4-aminophenoxyphenyl)propane (BAPP), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), bis[4-(aminophenoxy)phenyl] sulfone (BAPS), 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,5,3',5'-tetramethyl-4,4'-Diaminodiphenylmethane, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis(4-aminophenoxyphenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, benzidine, 3,3'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4"-diamino-p-terphenyl, 3,3"-diamino-p-terphenyl, bis(p-aminocyclohexyl)methane, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 4-(1H,1H,11H-eicosaf luoroundecanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro-1-butanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro-1-heptanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro-1-octanoxy)-1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4-(2,3,5,6-tetrafluorophenoxy)-1,3-Diaminobenzene, 4-(4-fluorophenoxy)-1,3-diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1-hexanoxy)-1,3-diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1-dodecanoxy)-1,3-diaminobenzene, (2,5)-diaminobenzotrifluoride, diaminotetra(trifluoromethyl)benzene, diaminopentafluoroethylbenzene, 2,5-diamino(perfluorohexyl)benzene, 2,5-diamino(perfluorobutyl)benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, octafluorobenzidine, 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,3-bis(anilino)hexafluoropropane, 1,4-bis(anilino)octafluorobutane, 1,5-bis(anilino)decafluoropentane, 1,7-bis(anilino)tetradecafluoroheptane, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3',5,5'-tetrakis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3'-bis(trifluoromethyl)-4,4'-diaminobenzophenone, 4,4'-diamino-p-terphenyl, 1,4-bis(p-aminophenyl)benzene, p-(4-amino-2-trifluoromethylphenoxy)benzene, bis(aminophenoxy)bis(trifluoromethyl)benzene, bis(aminophenoxy)tetrakis(trifluoromethyl)benzene, 2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(3-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(2-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(4-aminophenoxy)-3,5-dimethylphenyl}hexafluoropropane, 2,2-bis{4-(4-aminophenoxy)-3,5-ditrifluoromethylphenyl}hexafluoropropane, 4,Aromatic diamines derived from 4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-3-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-2-trifluoromethylphenoxy)diphenyl sulfone, 4,4'-bis(3-amino-5-trifluoromethylphenoxy)diphenyl sulfone, 2,2-bis{4-(4-amino-3-trifluoromethylphenoxy)phenyl}hexafluoropropane, bis{(trifluoromethyl)aminophenoxy}biphenyl, bis〔{(trifluoromethyl)aminophenoxy}phenyl〕hexafluoropropane, bis{2-〔(aminophenoxy)phenyl〕hexafluoroisopropyl}benzene, 4,4'-bis(4-aminophenoxy)octafluorobiphenyl, etc. are included. Also, aliphatic diamines such as dimer diamine, hexamethylenediamine, pentamethylenediamine, etc. are included.,

[0026] Among these acid anhydride components and diamine components, in the (a) polyamic acid used in the present invention, it is preferable that the total of the aromatic acid dianhydride residue derived from the aromatic tetracarboxylic dianhydride component and the aromatic diamine residue derived from the aromatic diamine component exceeds 50 mol% among all the acid anhydride residues and diamine residues. More preferably, it is 60 mol% or more, still more preferably 70 mol% or more, even more preferably 80 mol% or more, and most preferably 90 mol% or more. When the total of the aromatic acid dianhydride residue and the aromatic diamine residue is within the above range, it is presumed that the conjugated system spreads due to the large number of aromatic rings, and the charge transfer interaction is likely to be strengthened. Combined with the use of dihydrolevoglucosenone as the (b) organic solvent described later, light absorption is likely to occur up to the long wavelength side. Here, the aromatic acid dianhydride residue and the aromatic diamine residue may have not only aromatic groups but also aliphatic groups and alicyclic groups other than aromatic groups, but are excluded when they do not contain aromatic groups. In the present invention, it is preferable that the aromatic group refers to the aromatic group derived from the above-mentioned aromatic tetracarboxylic dianhydride or aromatic diamine compound.

[0027] (Synthesis of polyamic acid) (a) Polyamic acid can be produced by reacting the above-mentioned acid anhydride component and diamine component in an organic solvent. For example, the above-mentioned acid anhydride component and diamine component are dissolved in an organic solvent in approximately equimolar amounts, and then stirred at a temperature in the range of usually 0°C to 100°C for a range of 30 minutes to 24 hours to carry out a polymerization reaction. In the reaction, it is preferable that the resulting precursor is within the range of 5 to 30% by mass in the organic solvent, and more preferably, the reaction components are dissolved so as to be within the range of 7 to 20% by mass. Examples of the organic solvent used in the polymerization reaction include the component (b) described below.

[0028] The synthesized (a) polyamic acid generally has excellent solvent solubility, so it is usually advantageous to use it as a reaction solvent solution. However, if necessary, it can be concentrated, diluted, or replaced with another organic solvent.

[0029] <(b) Organic solvent> The organic solvent of the component (b) used in the present invention can be used for the polymerization reaction of the acid anhydride component and diamine component, which are the raw materials of the above-mentioned (a) polyamic acid, and is not limited as long as it can dissolve the polyamic acid prepared therefrom well, but it is essential to contain dihydrolevoglucosenone (trademark: Cyrene). Dihydrolevoglucosenone has the following chemical structure. [Chemical formula]

[0030] Since dihydrolevoglucosenone can be synthesized from renewable cellulose waste, which is a bio-based raw material, it is a carbon-neutral solvent with high safety and low environmental impact. In addition to such properties, it has physical properties similar to those of bipolar aprotic organic solvents, so it also has high versatility as an organic solvent. For the dihydrolevoglucosenone used in the present invention, commercially available products can be used.

[0031] In the present invention, it has been found that by using dihydrolevoglucosenone as an essential component in (a) the polymerization reaction solvent of polyamic acid or an organic solvent added after synthesizing polyamic acid, the property of light absorption occurring up to the long wavelength side is imparted. That is, it has been found that the obtained polyamic acid (polyamic acid composition) and polyimide are colored or blackened. Although the detailed mechanism is not clear, as can be confirmed in the examples described later, it is a property confirmed not only as the solvent during the polymerization reaction of polyamic acid but also when used as the solvent added to the polyamic acid obtained after the polymerization reaction. Therefore, it is presumed that dihydrolevoglucosenone causes a change in the higher-order structure of polyamic acid and polyimide by interacting with polyamic acid and polyimide. Here, regarding the speculation of such a mechanism of the present invention, even if in the future, explanations different from these speculations are given or different facts are found, it will not become an obstacle to the interpretation of the technical scope of the present invention or the implementation of the invention. The same applies to other descriptions in this specification.

[0032] Dihydrolevoglucosenone is preferably contained in an organic solvent at 10% by mass or more. More preferably, it is 20% by mass or more, and even more preferably 50% by mass or more. In order to reduce the amount of other organic solvents used and to express the above-mentioned properties, it is preferable to use more dihydrolevoglucosenone. Although it can be used at 100% by mass in component (b), it is preferable to appropriately adjust the amount used based on the compatibility with the acid anhydride component, diamine component, etc. used and the reactivity of the polymerization reaction.

[0033] Here, as the (b) organic solvent other than dihydrolevoglucosenone, known organic solvents used in the polymerization reaction of polyamic acid can be used. For example, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, γ-butyrolactone, etc. can be mentioned. These other organic solvents can be used alone or in combination of two or more.

[0034] Also, as the (b) organic solvent, it is preferable that the polar aprotic organic solvent is 60% by mass or more, more preferably 80% by mass or more, including dihydrolevoglucosenone. By using the polar aprotic organic solvent in such a range, the solubility of polyamic acid increases, and a composition excellent in coatability and film-forming property is obtained, which is preferable. As the polar aprotic organic solvent other than dihydrolevoglucosenone, it is more preferable to use N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP).

[0035] Furthermore, such (b) organic solvent preferably has a boiling point higher than that of water, more preferably, the boiling point (at normal pressure) is 120 °C or higher. When such an organic solvent with a high boiling point is used, problems such as the organic solvent volatilizing prior to water and polyamic acid precipitating when forming a film using the polyamic acid composition can be suppressed, which is preferable.

[0036] The content of the (b) organic solvent in the polyamic acid composition is not particularly limited, but it is preferably in the range of 5 to 30% by mass, more preferably in the range of 7 to 20% by mass, as the solid content concentration of the (a) polyamic acid.

[0037] (Other components) The polyamic acid composition of the present invention may contain, as necessary, fillers such as silicon dioxide, aluminum oxide, boron nitride, magnesium oxide, beryllium oxide, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphoric acids, etc., colorants such as organic pigments, inorganic pigments or dyes, and other components, as long as the object of the present invention is not inhibited. These components are usually preferably used in an amount of 10% by mass or less in the polyamic acid composition. These components can be used alone or in combination of two or more.

[0038] <Properties of polyamic acid composition> Regarding the polyamic acid composition of the present invention, (a) By containing dihydrolevoglucosenone during the polymerization of polyamic acid or in the subsequent composition, the property of light absorption up to the long wavelength side is imparted, and it is preferably more clearly colored or black. In that case, as confirmed in the examples described later, the light transmittance at 500 nm is 90% or less, and the lightness L * is preferably 95 or less. The more preferable light transmittance at 500 nm is 70% or less, and the more preferable lightness L * is 92 or less. By having such properties, when a polyimide film is formed, light-shielding property, concealing property, design property, etc. can be effectively exhibited. In addition, regarding such light transmittance and L * properties, it is a more preferable embodiment of the polyamic acid composition of the present invention that they are satisfied when the colorant as the other component and other specific compounds (for example, anthraquinone derivative tetraamine monomer described in Patent Document 1) or components contributing to coloring are not included.

[0039] Also, the polyamic acid composition of the present invention is not limited, but preferably has a solid content in the range of 5 to 30% by mass, more preferably in the range of 7 to 20% by mass.

[0040] Although the suitable range of the polyamic acid composition of the present invention can be appropriately selected depending on the solid content and the use, the viscosity is preferably in the range of 100 to 100,000 cP, and the more preferable viscosity is 1,000 to 50,000.

[0041] [Polyimide film] The polyimide film of the present invention is obtained by imidizing the polyamic acid composition having the above-described configuration as a precursor. The method of imidizing the polyamic acid composition is not particularly limited, and for example, heat treatment by heating within a temperature range of 80°C or higher and 400°C or lower for several minutes to 24 hours is preferably employed. In the present invention, when referring to "polyimide", resins composed of polymers having imide groups in their molecular structures, such as polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, polybenzimidazoleimide, etc., in addition to polyimide, may be included.

[0042] The polyimide film of the present invention is obtained by reacting an acid anhydride component and a diamine component in the same manner as the above-mentioned (a) polyamic acid, and contains an acid anhydride residue and a diamine residue. The charged amount (molar ratio) of the raw material components is the same as that of the (a) polyamic acid.

[0043] And the polyimide film of the present invention has the property of light absorption up to the long wavelength side in the same manner as the above-mentioned (a) polyamic acid, and is colored or blackened. Similarly to the above, such properties are exhibited even when the colorant as the other component and other specific compounds contributing to coloring (for example, anthraquinone derivative tetraamine monomers described in Patent Document 1) and components are not included, and are derived from dihydrolevoglucosenone contained in the (b) organic solvent used in the formation process of the polyimide film. Although the mechanism is considered to be as described above, in the polyimide film, in particular, it is presumed that due to the closer proximity of the molecular chains by imidization, the charge transfer interaction due to the specific higher-order structure formed by dihydrolevoglucosenone is strengthened, and in the expression of such properties, the light absorption at a longer wavelength is strengthened, resulting in a black polyimide film.

[0044] Regarding the above characteristics of the polyimide film, as will be confirmed in the examples described later, depending on the film thickness formed, the light transmittance at 500 nm and the brightness L * are found to decrease. In particular, when the film thickness is 15 μm or more, it can be seen that the decrease in light transmittance and brightness L * becomes significant. Although the details are not clear, it is presumed that the interaction between the two changes depending on the type and blending ratio of the polyamide monomer used, or the amount of dihydrolevoglucosenone used, etc., and the higher-order structure of the obtained polyimide film changes.

[0045] Here, the polyimide film of the present invention preferably has a light transmittance at 500 nm of 80% or less, more preferably 60% or less, and still more preferably 40% or less at a film thickness of 5 to 15 μm, and the brightness L * is preferably 90 or less, more preferably 80 or less, and still more preferably 70 or less. Also, at a film thickness of 15 to 25 μm, the light transmittance at 500 nm is preferably 70% or less, more preferably 50% or less, still more preferably 30% or less, and even more preferably 20% or less, and the brightness L * is preferably 90 or less, more preferably 70 or less, and still more preferably 55 or less. Further, at a film thickness of 25 to 50 μm, the light transmittance at 500 nm is preferably 60% or less, more preferably 40% or less, still more preferably 20% or less, and even more preferably 10% or less, and the brightness L * is preferably 90 or less, more preferably 70 or less, and even more preferably 50 or less. Depending on the application and purpose to be applied, the light transmittance at 500 nm and the brightness L * can be appropriately adjusted and used. By having such light transmittance and brightness, for example, in the applications of the insulating resin layer of FPC and the coverlay film, light-shielding properties, concealment properties, design properties, etc. can be effectively exhibited.

[0046] Also, in order to have such characteristics, in the polyimide film as well, the total of the aromatic dianhydride residues derived from the aromatic tetracarboxylic dianhydride component and the aromatic diamine residues derived from the aromatic diamine component is preferably more than 50 mol% among all the anhydride residues and diamine residues. More preferably, it is 60 mol% or more, still more preferably 70 mol% or more, even more preferably 80 mol% or more, and most preferably 90 mol% or more. The reason is considered to be the same as described above.

[0047] Regarding the characteristics other than the light transmittance and lightness of the polyimide film of the present invention, there are no particular limitations, and it may generally have the characteristics of a polyimide film (for example, optical properties, insulation properties, heat resistance, thermal conductivity, thermal expansion properties, adhesiveness, glass transition temperature, mechanical properties, etc.), or it may not have any or all of these characteristics, or it may have them at a level below the general level. Regarding the characteristics other than the light transmittance and lightness, it is preferably adjusted appropriately according to the use and purpose.

[0048] The thickness of the polyimide film of the present invention is not limited, but for example, it is preferably in the range of 2 to 100 μm, and more preferably in the range of 5 to 50 μm. If the thickness is less than 2 μm, problems such as wrinkles forming in the metal foil in the conveying process when manufacturing, for example, a metal-clad laminate, are likely to occur. On the contrary, if the thickness exceeds 100 μm, it may be suitable in terms of light shielding properties and concealment properties, but there is a risk of being disadvantageous in terms of other characteristics (such as the manifestation of thermal conductivity and toughness / flexibility).

[0049] [Method for forming polyimide film] As a method for forming a polyimide film, a known method can be adopted. For example, [1] a method of manufacturing a polyimide film by applying and drying a solution of a polyamic acid composition on a support substrate (e.g., a glass plate, a metal layer, a resin film, etc.) and then imidizing it (hereinafter referred to as the casting method), [2] a method of manufacturing a polyimide film by applying and drying a solution of a polyamic acid composition on a support substrate, peeling off the gel film of the polyamic acid from the support substrate, and then imidizing it. Further, when obtaining a film composed of a plurality of polyimide layers, as an embodiment of the manufacturing method, for example, [3] a method of repeating the application and drying of a solution of a polyamic acid composition on a support substrate a plurality of times and then performing imidization (hereinafter referred to as the sequential coating method), [4] a method formed by applying and drying a laminated structure of a polyamic acid composition simultaneously by multilayer extrusion on a support substrate and then performing imidization (hereinafter referred to as the multilayer extrusion method), etc. From the viewpoints of controlling the stability and dimensional stability of the film, or the adhesiveness to the support substrate, etc., it is preferable to form the polyimide film by the casting method or the sequential coating method. Particularly from the viewpoint of the stability of the film, it is good to obtain it as a laminate in which a polyimide film is laminated on a support substrate.

[0050] The method for applying a solution of a polyamic acid composition (or a polyimide solution) on a substrate is not particularly limited, and it can be applied, for example, with a coater such as a comma, die, knife, lip, etc. When forming a multilayer polyimide film, a method of repeating the operations of applying and drying a solution of a polyamic acid composition (or a polyimide solution) on a substrate is preferable. The polyimide film in the present invention may be a single layer or may be composed of a plurality of layers.

[0051] The polyimide film of the present invention can be a metal-clad laminate using a metal layer as a support substrate, and can also be made into a circuit board by processing the metal layer of the metal-clad laminate into a pattern by a conventional method to form a wiring layer. In that case, for the metal-clad laminate and the circuit board, known methods, forming procedures, circuit processing methods, etc. can be used without limitation.

Examples

[0052] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, various measurements and evaluations are as follows.

[0053] [Measurement of Viscosity] The viscosity at 25 °C was measured using an E-type viscometer (manufactured by Brookfield, trade name; DV-II+Pro). The rotation speed was set so that the torque was 10% to 90%, and after 2 minutes had elapsed since the start of the measurement, the value when the viscosity became stable was read.

[0054] [Measurement of Weight-Average Molecular Weight (Mw)] The weight-average molecular weight was measured by gel permeation chromatography (manufactured by Tosoh Corporation, trade name; HLC-8420GPC). Polystyrene was used as the standard substance, and N,N-dimethylacetamide (DMAc) was used as the developing solvent.

[0055] [Measurement of Light Transmittance, Calculation of Luminance L * of The transmittance was measured at each wavelength from 300 to 800 nm using a spectrophotometer (UV-3600 Plus manufactured by Shimadzu Corporation) (the transmittance at 500 nm at this time was designated as T500). The luminance L * was measured from the X, Y, Z values measured with the same apparatus, and L * = 116 (Y / Y n ) 1 / 3 - 16 was calculated from the formula. Y n represents the tristimulus values of a perfect diffusing reflecting surface, and when Y / Y n is 0.008856 or less, L * = 903.29 (Y / Y n ) was calculated from the formula. In the case of a solution of the polyamic acid composition (hereinafter sometimes referred to as the "polyamic acid solution"), the solution was placed in a 10 mm square quartz cell and measured using pure water as a reference. In the case of a polyimide film, it was measured using the same glass substrate as a reference in the state of being coated on the glass substrate.

[0056] The abbreviations used in this example represent the following compounds. BPDA: 3,3’,4,4’-Biphenyltetracarboxylic dianhydride PMDA: Pyromellitic dianhydride 6FDA: 2,2’-Bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride m-TB: 2,2’-Dimethyl-4,4’-diaminobiphenyl TPE-Q: 1,4-Bis(4-aminophenoxy)benzene 4,4’-DAPE: 4,4’-Diaminodiphenyl ether TFMB: 2,2’-Bis(trifluoromethyl)-4,4’-diaminobiphenyl DMAc: N,N-Dimethylacetamide Cyrene: Dihydrolevoglucosenone

[0057] (Example 1) <Preparation of Polyamic Acid Solution A> 3.9645 g of m-TB and 0.9630 g of TPE-Q were placed in a 300 ml separable flask and dissolved in 45 g of DMAc. Subsequently, 3.7931 g of PMDA was added to this solution and stirred, followed by the addition of 1.2794 g of BPDA. Then, 45 g of Cyrene was added to make the solid content 10% by mass, and the mixture was stirred at room temperature for 5 hours to carry out the polymerization reaction, obtaining Polyamic Acid Solution A. The viscosity of Polyamic Acid Solution A was 6,906 cp, and the molecular weight Mw was 110,015.

[0058] <Preparation of Polyimide Film A> The Polyamic Acid Solution A obtained above was applied onto a glass substrate with a thickness of 0.7 mm so that the film thickness after heat treatment was 5 - 15, 15 - 25, 25 - 50 μm. After heating and drying at 90 - 130 °C, stepwise heat treatment was carried out from 150 °C to 360 °C for 10 minutes to complete imidization, preparing Polyimide Film A with a glass substrate.

[0059] (Example 2) <Preparation of Polyamic Acid Solution B> 8.5170 g of TFMB was placed in a 300 ml separable flask and dissolved in 42.5 g of DMAc. Subsequently, 5.0208 g of PMDA was added to this solution and stirred, followed by the addition of 1.4623 g of 6FDA. Then, 42.5 g of Cyrene was added to make the solid content 15% by mass, and the mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining a polyamic acid solution B. The viscosity of the polyamic acid solution B was 7,025 cp, and the molecular weight Mw was 81,440.

[0060] A polyimide film B with a glass substrate was prepared in the same manner as in Example 1, except that the polyamic acid solution was used as B.

[0061] (Example 3) <Preparation of polyamic acid solution C> 3.1270 g of TFMB was placed in a 300 ml separable flask and dissolved in 30.0 g of Cyrene. Subsequently, 4.3730 g of 6FDA was added to this solution, and 12.5 g of Cyrene was added to make the solid content 15% by mass. Then, the mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining a polyamic acid solution C. The viscosity of the polyamic acid solution C was 7,509 cp, and the molecular weight Mw was 52,936.

[0062] A polyimide film C with a glass substrate was prepared in the same manner as in Example 1, except that the polyamic acid solution was used as C.

[0063] (Example 4) <Preparation of polyamic acid solution D> 7.2152 g of 4,4'-DAPE was placed in a 300 ml separable flask and dissolved in 42.5 g of DMAc. Subsequently, 7.7848 g of PMDA was added to this solution, and 42.5 g of Cyrene was added to make the solid content 15% by mass. Then, the mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining a polyamic acid solution D. The viscosity of the polyamic acid solution D was 1,508 cp, and the molecular weight Mw was 46,535.

[0064] A polyimide film D with a glass substrate was prepared in the same manner as in Example 1, except that the polyamic acid solution was used as D.

[0065] (Comparative Example 1) (Preparation of Polyamic Acid Solution E) 5.9471 g of m-TB and 1.4445 g of TPE-Q were placed in a 300 ml separable flask and dissolved in 45 g of DMAc. Next, 5.6895 g of PMDA was added to this solution and stirred, followed by the addition of 1.9190 g of BPDA. 40 g of DMAc was added to make the solid content 15% by mass, and the mixture was stirred at room temperature for 5 hours to carry out a polymerization reaction, obtaining polyamic acid solution E. The viscosity of polyamic acid solution E was 24,964 cp and the molecular weight Mw was 115,815.

[0066] A polyimide film E on a glass substrate was prepared in the same manner as in Example 1, except that polyamic acid solution E was used.

[0067] (Example 5) (Preparation of Polyamic Acid Solution F) 10 g of the polyamic acid solution E obtained in Comparative Example 1 was collected in a 100 ml plastic container, and 8.5 g of Cyrene was added so that the content ratio of DMAc and Cyrene became 1:1. After stirring with a medicine spoon until uniform, it was left standing in a cool and dark place for 1 day to obtain polyamic acid solution F. The viscosity of polyamic acid solution F was 3,540 cp.

[0068] A polyimide film F on a glass substrate was prepared in the same manner as in Example 1, except that polyamic acid solution F was used.

[0069] (Example 6) (Preparation of Polyamic Acid Solution G) 10 g of the polyamic acid solution E obtained in Comparative Example 1 was collected in a 100 ml plastic container, and 2.125 g of Cyrene was added so that the content ratio of DMAc and Cyrene became 4:1. After stirring with a medicine spoon until uniform, it was left standing in a cool and dark place for 1 day to obtain polyamic acid solution G. The viscosity of polyamic acid solution G was 15,161 cp.

[0070] A polyimide film G on a glass substrate was prepared in the same manner as in Example 1, except that polyamic acid solution G was used.

[0071] (Comparative Example 2) <Preparation of Polyamic Acid Solution H> 5.9437 g of TFMB was placed in a 300 ml separable flask and dissolved in 30.0 g of DMAc. Next, 3.5286 g of PMDA was added to this solution and stirred, and then 1.0277 g of 6FDA was added. Subsequently, 29.5 g of DMAc was added so that the solid content became 15% by mass, and the mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining polyamic acid solution H. The viscosity of polyamic acid solution H was 10,890 cp, and the molecular weight Mw was 148,927.

[0072] A polyimide film H with a glass substrate was prepared in the same manner as in Example 1, except that polyamic acid solution H was used.

[0073] (Comparative Example 3) <Preparation of Polyamic Acid Solution I> 6.2648 g of TFMB was placed in a 300 ml separable flask and dissolved in 45.0 g of DMAc. Next, 8.7352 g of 6FDA was added to this solution, and 40.0 g of DMAc was added so that the solid content became 15% by mass. The mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining polyamic acid solution I. The viscosity of polyamic acid solution I was 1,639 cp, and the molecular weight Mw was 134,449.

[0074] A polyimide film I with a glass substrate was prepared in the same manner as in Example 1, except that polyamic acid solution I was used.

[0075] (Comparative Example 4) <Preparation of Polyamic Acid Solution J> 7.2152 g of 4,4'-DAPE was placed in a 300 ml separable flask and dissolved in 45.0 g of DMAc. Next, 7.7848 g of PMDA was added to this solution, and 40.0 g of DMAc was added so that the solid content became 15% by mass. The mixture was stirred at room temperature for 5 hours to conduct a polymerization reaction, obtaining polyamic acid solution J. The viscosity of polyamic acid solution J was 7,488 cp, and the molecular weight Mw was 139,049.

[0076] A polyimide film J on a glass substrate was prepared in the same manner as in Example 1, except that the polyamic acid solution was designated as J.

[0077] The light transmittance characteristics of the obtained polyamic acid and the polyimide film on the glass substrate are shown in Table 1.

[0078]

Table 1

[0079] It was found that the polyamic acid containing Cyrene gave a polyamic acid solution with a decreased light transmittance at 500 nm and colored. Also, the polyimide film had a greatly decreased light transmittance at 500 nm, and a black polyimide film with a greatly reduced brightness was obtained. In Example 5, even when Cyrene was added later to the polyamic acid solution in which polymerization had sufficiently proceeded with DMAc, the same effect of coloring or blackening was obtained. Also, from Example 6, it was confirmed that the effect of coloring or blackening was obtained even when the amount of Cyrene was less than that of DMAc.

[0080] As described above, the embodiments of the present invention have been described in detail for illustrative purposes, but the present invention is not limited to the above embodiments.

Claims

1. The following components (a) and (b); (a) A polyamic acid having an acid anhydride residue derived from a tetracarboxylic dianhydride component and a diamine residue derived from a diamine component, (b) An organic solvent, A polyamic acid composition containing the same, The component (b) is characterized in that it contains dihydrolevoglucosenone. The polyamic acid composition.

2. The component (a) is characterized in that the total of the aromatic acid dianhydride residue derived from the aromatic tetracarboxylic dianhydride component and the aromatic diamine residue derived from the aromatic diamine component exceeds 50 mol% in the acid anhydride residue and the diamine residue. The polyamic acid composition according to Claim 1.

3. The component (b) is characterized in that it contains 60% by mass or more of a polar aprotic organic solvent. The polyamic acid composition according to Claim 1.

4. The component (b) is characterized in that it contains 10% by mass or more of dihydrolevoglucosenone. The polyamic acid composition according to Claim 1.

5. The polyamic acid composition according to Claim 1, characterized in that the solid content concentration of the component (a) is in the range of 7 to 20% by mass.

6. The light transmittance at 500 nm is 90% or less, and the lightness L ＊ The polyamic acid composition according to claim 1, characterized in that it is 95 or less.

7. A polyimide film obtained by imidizing the polyamic acid composition according to any one of Claims 1 to 6, In the film thickness range of 5 to 15 μm, the light transmittance at 500 nm is 80% or less, and the lightness L ＊ is 90 or less. The polyimide film is characterized by this.

8. The total of the aromatic acid dianhydride residue derived from the aromatic tetracarboxylic dianhydride component and the aromatic diamine residue derived from the aromatic diamine component exceeds 50 mol% in the acid anhydride residue and the diamine residue. The polyimide film according to Claim 7.

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