Polyamic acid composition, polyimide, polyimide film, laminate, electronic device, and method for producing polyamic acid composition

Abstract

The polyamide acid composition comprises polyamide acid, an organic solvent, aminophenol and methyl aminobenzoate. The polyamic acid has a 4-aminobenzoic acid 4-aminobenzoate residue as a diamine residue. The content of 4-aminobenzoic acid 4-aminobenzoic acid 4-aminobenzoic acid ester residues is 70 mol% or more with respect to all diamine residues constituting the polyamic acid. Using a sample obtained by diluting the polyamic acid composition to a polyamic acid concentration of 1 mass%, the content of aminophenol as determined by gas chromatography-mass spectrometry is 1-30 ppm by mass (inclusive) relative to the total amount of the sample. Using a sample obtained by diluting the polyamic acid composition to a polyamic acid concentration of 1 mass%, the content of methyl aminobenzoate obtained by gas chromatography-mass spectrometry is 0.01-0.10 ppm by mass (inclusive) with respect to the total amount of the sample.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyamic acid composition, a polyimide, a polyimide film, a laminate, an electronic device, and a method for producing a polyamic acid composition. The present application also relates to an electronic device material using a polyimide, a thin film transistor (TFT) substrate, a flexible display substrate, a color filter, a printed matter, an optical material, an image display device (more specifically, a liquid crystal display device, an organic EL, electronic paper, etc.), a 3D display, a solar cell, a touch panel, a transparent conductive film substrate, and a substitute material for a member currently using glass. BACKGROUND

[0002] With rapid progress of electronic devices such as liquid crystal displays, organic ELs, electronic paper, etc., solar cells, touch panels, etc., the devices are being increasingly developed in terms of thinness, lightness, and flexibility. In these devices, polyimides are used as a substrate material instead of glass substrates.

[0003] In these devices, various electronic elements such as thin film transistors, transparent electrodes, etc. are formed on the substrates, and the formation of these electronic elements requires high-temperature processes. Polyimides have sufficient heat resistance to adapt to high-temperature processes, and the coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic elements, so that internal stress is less likely to occur, and polyimides are suitable as a substrate material for flexible displays, etc.

[0004] Generally, aromatic polyimides are colored brown by intramolecular conjugation and formation of charge transfer (CT) complexes, but in top-emission type organic ELs, etc., light is extracted from the opposite side of the substrate, so that the substrate is not required to be transparent, and conventional aromatic polyimides have been used. However, in cases where light emitted from display elements passes through the substrate, such as in transparent displays, bottom-emission type organic ELs, liquid crystal displays, and in cases where sensors, camera modules, etc. are arranged on the back surface of the substrate in order to make a smart phone, etc. into a full-surface display (without gaps), the substrate is also required to have high optical properties (more specifically, transparency, etc.).

[0005] From such a background, a material having heat resistance equivalent to that of conventional aromatic polyimides and excellent in coloration reduction and transparency is required.

[0006] In order to reduce the coloration of polyimides, a technique of using aliphatic monomers to suppress the formation of CT complexes (Patent Documents 1 and 2), a technique of improving transparency by using monomers having fluorine atoms (Patent Document 3), and a technique of improving transparency by using monomers having a fluorene structure (Patent Document 4) are known.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT DOCUMENTS

[0009] Patent Literature 1: Japanese Patent Application Publication No. 2016-29177

[0010] Patent Literature 2: Japanese Patent Application Publication No. 2012-41530

[0011] Patent Literature 3: Chinese Patent Application Publication No. 201713726

[0012] Patent Literature 4: International Publication No. 2019 / 195148 SUMMARY

[0013] PROBLEMS TO BE SOLVED BY THE INVENTION

[0014] The present inventors conducted verification, and as a result, it was ascertained that if the polyamic acid composition described in Patent Literatures 1 to 4 is applied to a support, and the polyamic acid is subjected to imidization, there is a tendency that internal stress generated at the interface of the polyimide film and the support becomes large. Hereinafter, the internal stress generated at the interface of the polyimide film and the support is sometimes simply referred to as “internal stress”. If the internal stress becomes large, it can be difficult to apply to electronic devices.

[0015] In addition, the technology described in Patent Literatures 1 to 4 has room for improvement in terms of improving the transparency of the polyimide.

[0016] The present invention was completed in view of the above-described actual circumstances, and aims to provide a polyimide having reduced internal stress and excellent transparency, and a polyimide film, a laminate, and an electronic device each containing the polyimide. In addition, the present invention also aims to provide a polyamic acid composition containing a polyamic acid as a precursor of the polyimide, and a method for producing the same.

[0017] SOLUTION TO PROBLEM

[0018] <Embodiments of the Invention>

[0019] The present invention includes the following embodiments.

[0020] [1] A polyamic acid composition comprising a polyamic acid, an organic solvent, an aminophenol, and methyl aminobenzoate,

[0021] The aforementioned polyamic acid has a 4-aminophenyl 4-aminobenzoate residue as a diamine residue,

[0022] The aforementioned 4-aminophenyl 4-aminobenzoate residue has a content of 70 mol% or more with respect to all diamine residues constituting the aforementioned polyamic acid,

[0023] The content of the aminophenol obtained by gas chromatography mass spectrometry is 1 mass ppm or more and 30 mass ppm or less with respect to the total amount of the sample obtained by diluting the aforementioned polyamic acid composition to a polyamic acid concentration of 1 mass %,

[0024] The content of the methyl aminobenzoate obtained by gas chromatography mass spectrometry is 0.01 mass ppm or more and 0.10 mass ppm or less with respect to the total amount of the sample obtained by diluting the aforementioned polyamic acid composition to a polyamic acid concentration of 1 mass %.

[0025] [2] The polyamic acid composition according to the aforementioned [1], wherein the Gardner color and the Hunter color measured in a 1 cm light path length cuvette using a sample obtained by diluting the aforementioned polyamic acid composition to a polyamic acid concentration of 1 mass % are 0.3 or less and 10 or less, respectively.

[0026] [3] The polyamic acid composition according to the aforementioned [1] or [2], wherein the polyamic acid has one or more selected from the group consisting of a 4-valent organic group represented by the following Chemical Formula (1), a 4-valent organic group represented by the following Chemical Formula (2), a 4-valent organic group represented by the following Chemical Formula (3), a 4-valent organic group represented by the following Chemical Formula (4), a 4-valent organic group represented by the following Chemical Formula (5), a 4-valent organic group represented by the following Chemical Formula (6), a 4-valent organic group represented by the following Chemical Formula (7), a 4-valent organic group represented by the following Chemical Formula (8), a 4-valent organic group represented by the following Chemical Formula (9), and a 4-valent organic group represented by the following Chemical Formula (10) as a tetracarboxylic dianhydride residue.

[0027]

[0028] [4] A polyimide which is an imidized product of the aforementioned polyamic acid contained in the polyamic acid composition according to any one of the aforementioned [1] to [3].

[0029] [5] A polyimide film comprising the polyimide according to the aforementioned [4].

[0030] [6] The polyimide film according to the aforementioned [5], wherein the yellowness is 20 or less.

[0031] [7] The polyimide film according to the aforementioned [5] or [6], wherein the transmittance of light having a wavelength of 400 nm is 8% or more.

[0032] [8] A laminate having a support and the polyimide film according to any one of the aforementioned [5] to [7].

[0033] [9] The laminate according to the preceding [8], wherein the support is a glass substrate,

[0034] The internal stress between the aforementioned polyimide film and the aforementioned glass substrate is 30 MPa or less.

[0035]

[10] An electronic device having the polyimide film according to any one of the preceding [5] to [7] and an electronic element disposed on the polyimide film.

[0036]

[11] A method for producing the polyamic acid composition according to any one of the preceding [1] to [3],

[0037] which has a step S1 of reacting a diamine with a tetracarboxylic dianhydride in an organic solvent,

[0038] the aforementioned diamine includes 4-aminophenyl 4-aminobenzoate,

[0039] the content of the aforementioned 4-aminophenyl 4-aminobenzoate is 70 mol% or more relative to the total amount of the aforementioned diamine,

[0040] the aforementioned 4-aminophenyl 4-aminobenzoate is supplied to the aforementioned step S1 in the form of a raw material monomer containing impurities,

[0041] the aforementioned impurities include aminophenol and methyl 4-aminobenzoate,

[0042] the Gardner color and the Hunter color of a 1 mass% N-methyl-2-pyrrolidone solution of the aforementioned raw material monomer, measured in a cuvette with an optical path length of 1 cm, are 3.0 or less and 200 or less, respectively.

[0043]

[12] The method for producing the polyamic acid composition according to the preceding

[11] , wherein the content of the aforementioned aminophenol in the aforementioned raw material monomer is 0.60 mass% or less relative to the total amount of the aforementioned 4-aminophenyl 4-aminobenzoate,

[0044] the content of the aforementioned methyl 4-aminobenzoate in the aforementioned raw material monomer is 0.60 mass% or less relative to the total amount of the aforementioned 4-aminophenyl 4-aminobenzoate.

[0045] Effects of the Invention

[0046] According to the present application, it is possible to provide a polyimide having reduced internal stress and excellent transparency, and a polyimide film, a laminate, and an electronic device containing the same. In addition, according to the present application, it is also possible to provide a polyamic acid composition containing a polyamic acid as a precursor of the polyimide and a method for producing the same. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. Furthermore, all academic and patent documents described in this specification are incorporated herein by reference.

[0048] First, the terms used in this specification will be explained. “Structural unit” refers to a repeating unit that constitutes a polymer. “Polyamic acid” is a polymer that contains a structural unit represented by the following general formula (11) (hereinafter sometimes referred to as “structural unit (11)”).

[0049]

[0050] In general formula (11), A 1 Indicates a tetracarboxylic dianhydride residue (derived from a tetravalent organic group of tetracarboxylic dianhydride), A 2 It represents a diamine residue (a divalent organic group derived from a diamine).

[0051] The content of structural unit (11) relative to all structural units constituting polyamic acid is, for example, 50 mol% or more and 100 mol% or less, preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, further preferably 80 mol% or more and 100 mol% or less, and even more preferably 90 mol% or more and 100 mol% or less, and can be 100 mol%.

[0052] Hereinafter, the term "system" is sometimes added after the compound name to collectively refer to the compound and its derivatives. Additionally, when "system" is added after the compound name to indicate the polymer name, unless otherwise specified, it means that the repeating unit of the polymer originates from the compound or its derivatives. Furthermore, tetracarboxylic dianhydrides are sometimes written as "acid dianhydrides".

[0053] Unless otherwise specified, the ingredients and functional groups exemplified in this instruction manual may be used alone or in combination with two or more.

[0054] <Preferred Embodiments of the Invention>

[0055] The polyamic acid composition of this embodiment comprises polyamic acid (hereinafter, sometimes referred to as "specific polyamic acid"), an organic solvent, aminophenol, and methyl aminobenzoate. The specific polyamic acid has a 4-aminobenzoic acid 4-aminophenyl ester residue as a diamine residue. In the specific polyamic acid, the content of the 4-aminobenzoic acid 4-aminophenyl ester residue is 70 mol% or more relative to all diamine residues (100 mol%) constituting the specific polyamic acid. Using a sample obtained by diluting the polyamic acid composition of this embodiment to a concentration of 1 wt% of the specific polyamic acid, the content of aminophenol obtained by gas chromatography-mass spectrometry is 1 ppm or more and 30 ppm or less relative to the total amount of the sample. Using a sample obtained by diluting the polyamic acid composition of this embodiment to a concentration of 1 wt% of the specific polyamic acid, the content of methyl aminobenzoate obtained by gas chromatography-mass spectrometry is 0.01 ppm or more and 0.10 ppm or less relative to the total amount of the sample.

[0056] As a diluting solvent for preparing the above-mentioned sample (specifically, the sample used when determining the content of aminophenol and the content of methyl aminobenzoate), an example of an organic solvent of the same kind as the organic solvent contained in the polyamic acid composition can be cited.

[0057] Hereinafter, gas chromatography-mass spectrometry will sometimes be referred to as "GC / MS analysis". Additionally, when using a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass, the content of aminophenol (relative to the total amount of the sample) obtained by GC / MS analysis is sometimes abbreviated as "content of aminophenol in the polyamic acid composition". Similarly, when using a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass, the content of methyl aminobenzoate (relative to the total amount of the sample) obtained by GC / MS analysis is sometimes abbreviated as "content of methyl aminobenzoate in the polyamic acid composition". The methods for determining the content of aminophenol in the polyamic acid composition and the methods for determining the content of methyl aminobenzoate in the polyamic acid composition are the same as or based on the methods described in the examples below. Furthermore, 4-aminobenzoic acid 4-aminophenyl ester is sometimes referred to as "4-BAAB".

[0058] Polyimides obtained from polyamic acids containing 4-BAAB residues have a rigid structure due to the 4-BAAB residues, resulting in a low CTE and thus reducing internal stress. Specific polyamic acids contain 4-BAAB residues at a content of 70 mol% or more relative to all diamine residues; therefore, polyimides obtained using the polyamic acid compositions of this embodiment can reduce internal stress.

[0059] In addition, 4-BAAB, due to the electron-withdrawing properties of the carbonyl group in the ester bond, can suppress the formation of CT complexes, making it suitable as a monomer component for polyimides with excellent transparency.

[0060] On the other hand, commercially available 4-BAAB (raw material monomer) used for the synthesis of polyamic acid typically contains aminophenol and methyl aminobenzoate as impurities. Examples of aminophenol include one or more selected from the group consisting of p-aminophenol, m-aminophenol, and o-aminophenol. Examples of methyl aminobenzoate include one or more selected from the group consisting of methyl 2-aminobenzoate, methyl 3-aminobenzoate, and methyl 4-aminobenzoate.

[0061] Hereinafter, a raw material (usually in powder form) containing 4-BAAB for synthesizing polyamic acid and impurities will sometimes be referred to as a "4-BAAB composition". The aminophenol and methyl aminobenzoate in the polyamic acid composition of this embodiment are, for example, residual components of the impurities in the 4-BAAB composition. According to the inventors' research, if a 4-BAAB composition containing a large amount of impurities is dissolved in a polymerization solvent, the solution is colored yellow or brown, and the transparency of the polymerized polyimide film decreases.

[0062] Based on the results of GC / MS analysis of the 4-BAAB composition containing a large number of impurities, impurities considered to be the cause of the aforementioned discoloration include aminotoluene, aminophenol (specifically, p-aminophenol, etc.), 2,4,4-trimethyl-1,3-pentanediol-1-isobutyrate, methyl aminobenzoate (specifically, methyl 4-aminobenzoate, etc.), ethyl aminobenzoate (specifically, ethyl 4-aminobenzoate, etc.), 4-aminobenzoylhydrazine, 4-(1H-benzimidazole-2- (estimated molecular weight 209), p-aminobenzoic acid, 4-aminophenol derivatives (estimated molecular weight 213), 4-amino-N-(2-ethoxyphenyl)benzamide derivatives (estimated molecular weight 256), 4-(dimethylamino)-N-(2-ethoxyphenyl)benzamide derivatives (estimated molecular weight 256), N-(4-{[2-(3-phenylpropionyl)hydrazino]carbonyl}phenyl)propionamide derivatives (estimated molecular weight 284), and their similar structures, etc.

[0063] The inventors conducted in-depth research and found that as the content of monoamines as impurities increases, the transparency of the obtained polyimide film decreases. In particular, when the amount of aminophenol and methyl aminobenzoate in the 4-BAAB composition increases, the transparency of the obtained polyimide film decreases significantly.

[0064] In this embodiment, the content of aminophenol in the polyamic acid composition is less than 30 ppm by mass, and the content of methyl aminobenzoate in the polyamic acid composition is less than 0.10 ppm by mass. Therefore, the decrease in transparency of the obtained polyimide film can be suppressed, and the original function of 4-BAAB (the function of improving transparency by inhibiting the formation of CT complexes) can be fully utilized. Therefore, the polyimide obtained using the polyamic acid composition of this embodiment has excellent transparency.

[0065] It should be noted that if the content of aminophenol in the polyamic acid composition is in the range of 1 ppm by mass or more and 30 ppm by mass or less, then trace amounts of aminophenol tend to function as an accelerator for the imidization reaction. Additionally, if the content of methyl aminobenzoate in the polyamic acid composition is in the range of 0.01 ppm by mass or more and 0.10 ppm by mass or less, then trace amounts of methyl aminobenzoate tend to function as an accelerator for the imidization reaction.

[0066] In this embodiment, in order to obtain a polyimide with further reduced internal stress and better transparency, the content of 4-BAAB residues is preferably 80 mol% or more, more preferably 90 mol% or more, more preferably 95 mol% or more, and may also be 100 mol% relative to all diamine residues constituting the specific polyamic acid.

[0067] In this embodiment, to obtain a polyimide with better transparency, the content of aminophenol in the polyamic acid composition is preferably 28 ppm by mass or less, more preferably 25 ppm by mass or less. Furthermore, in this embodiment, to obtain a polyimide with better transparency, the content of methyl aminobenzoate in the polyamic acid composition is preferably 0.08 ppm by mass or less, more preferably 0.05 ppm by mass or less.

[0068] The content of aminophenol and methyl aminobenzoate in the polyamic acid composition can both be adjusted by the preparation conditions of the 4-BAAB composition. Specifically, this can be adjusted by changing at least one of the purification methods for the 4-BAAB raw material (4-nitrobenzoic acid 4-nitrobenzene) (specifically, recrystallization, activated carbon treatment, etc.) and the purification methods for the obtained 4-BAAB composition (specifically, activated carbon treatment, recrystallization, etc.). Furthermore, when multiple purification methods are used, the aforementioned content can also be adjusted by changing the order in which the purification methods are performed. It should be noted that activated carbon treatment is effective in reducing aminophenol. On the other hand, recrystallization is effective in reducing methyl aminobenzoate.

[0069] In this embodiment, to obtain polyimide with superior transparency, a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass using a specific polyamic acid is used. The Gardner colorimetry measured in a cuvette with an optical path length of 1 cm is preferably 0.3 or less, more preferably 0.2 or less. Furthermore, in this embodiment, to obtain polyimide with superior transparency, a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass using a specific polyamic acid is used. The Hassen colorimetry measured in a cuvette with an optical path length of 1 cm is preferably 10 or less, more preferably 8 or less.

[0070] Hereinafter, the Hassen color number will sometimes be referred to as "APAH". Additionally, when a sample obtained by diluting a polyamic acid composition to a concentration of 1% by mass is used, the Gardner colorimetric value measured in a cuvette with an optical path length of 1 cm will be abbreviated as "Galdner colorimetric value of the polyamic acid composition". Furthermore, when a sample obtained by diluting a polyamic acid composition to a concentration of 1% by mass is used, the APAH measured in a cuvette with an optical path length of 1 cm will be abbreviated as "APAH of the polyamic acid composition". As a diluting solvent used to prepare the above-mentioned sample (specifically, the sample used to determine the Gardner colorimetric value and APAH of the polyamic acid composition), an organic solvent of the same type as the organic solvent contained in the polyamic acid composition can be cited as an example.

[0071] The methods for determining the Gardner color and the APAH of the polyamic acid composition are the same as or based on the methods described in the examples below. There is a tendency that the lower the content of aminophenol and methyl aminobenzoate in the polyamic acid composition, the lower the Gardner color and APAH of the polyamic acid composition. There are no lower limits for the Gardner color and the APAH of the polyamic acid composition; both can be 0.

[0072] The specific polyamic acid contained in the polyamic acid composition of this embodiment has tetracarboxylic dianhydride residues and diamine residues.

[0073] In the synthesis of specific polyamic acids, dianhydrides (monomers) that can be used include, for example: pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (hereinafter, sometimes referred to as "s-BPDA"), 2,3,3',4'-biphenyltetracarboxylic dianhydride (hereinafter, sometimes referred to as "a-BPDA"), 2,2',3,3'-biphenyltetracarboxylic dianhydride (hereinafter, sometimes referred to as "i-BPDA"), p-phenylene bis(triphenylene ester anhydride), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1 2,5,6-Naphthalenetetracarboxylic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4'-oxophthalic anhydride (hereinafter, sometimes referred to as "ODPA"), 3,4'-oxophthalic anhydride (hereinafter, sometimes referred to as "a-ODPA"), spiro[11H-difluoro[3,4-b:3',4'-i]xanthon-11,9'-[9H]fluorene]-1,3,7,9-tetraone (hereinafter, sometimes referred to as "SFDA"), 9,9-bis(3,4-dicarboxyphenyl) Fluorene dianhydride (hereinafter sometimes referred to as "BPAF"), dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2'-oxodispiro[bicyclo[2.2.1]heptane-2,1'-cyclopentane-3',2''-bicyclo[2.2.1]heptane]-5,6:5'',6''-tetracarboxylic dianhydride, 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic acid-5,5',6,6 '-Dianhydride (hereinafter, sometimes referred to as "BNBDA"), decahydro-1H,3H-4,10:5,9-dimethylbridgednaphtho[2,3-c:6,7-c']difuran-1,3,6,8-tetraone (hereinafter, sometimes referred to as "DNDA"), norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid dianhydride (hereinafter, sometimes referred to as "CpODA"), and their derivatives, which may be used alone or in combination.

[0074] To obtain polyimides that further reduce internal stress and have better transparency, the specific polyamic acid preferably has one or more of the following as tetracarboxylic dianhydride residues: s-BPDA residue, a-BPDA residue, i-BPDA residue, ODPA residue, a-ODPA residue, SFDA residue, BPAF residue, DNDA residue, BNBDA residue, and CpODA residue. More preferably, it has one or more of the following as tetracarboxylic dianhydride residues: s-BPDA residue, a-BPDA residue, SFDA residue, BPAF residue, and ODPA residue.

[0075] The s-BPDA residue is a tetravalent organic group represented by the following chemical formula (1). The a-BPDA residue is a tetravalent organic group represented by the following chemical formula (2). The i-BPDA residue is a tetravalent organic group represented by the following chemical formula (3). The ODPA residue is a tetravalent organic group represented by the following chemical formula (4). The a-ODPA residue is a tetravalent organic group represented by the following chemical formula (5). The SFDA residue is a tetravalent organic group represented by the following chemical formula (6). The BPAF residue is a tetravalent organic group represented by the following chemical formula (7). The DNDA residue is a tetravalent organic group represented by the following chemical formula (8). The BNBDA residue is a tetravalent organic group represented by the following chemical formula (9). The CpODA residue is a tetravalent organic group represented by the following chemical formula (10).

[0076]

[0077] To obtain a polyimide capable of further reducing internal stress, the specific polyamic acid preferably has s-BPDA residues as tetracarboxylic dianhydride residues. To obtain a polyimide capable of further reducing internal stress, the content of s-BPDA residues relative to all tetracarboxylic dianhydride residues constituting the specific polyamic acid (100 mol%) is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and may also be 100 mol%.

[0078] To obtain polyimides with superior transparency, the specific polyamic acid preferably has one or more of the tetracarboxylic dianhydride residues selected from the group consisting of α-BPDA residues, SFDA residues, BPAF residues, and ODPA residues. To obtain polyimides with even better transparency, the content of one or more residues selected from the group consisting of α-BPDA residues, SFDA residues, BPAF residues, and ODPA residues is preferably 1 mol% or more and 50 mol% or less, more preferably 5 mol% or more and 40 mol% or less, and even more preferably 10 mol% or more and 30 mol% or less, relative to all tetracarboxylic dianhydride residues constituting the specific polyamic acid (100 mol%).

[0079] To obtain polyimide with further reduced internal stress and further improved transparency, the content of one or more residues selected from the group consisting of s-BPDA residues, a-BPDA residues, SFDA residues, BPAF residues and ODPA residues is preferably 60 mol% or more, more preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and may also be 100 mol% relative to all tetracarboxylic dianhydride residues (100 mol%) constituting the specific polyamic acid.

[0080] When synthesizing specific polyamic acids, diamine monomers other than 4-BAAB can also be used. Examples of diamines (monomers) that can be used besides 4-BAAB include: p-phenylenediamine, 1,3-bis(3-aminopropyl)tetramethyldisiloxane (hereinafter sometimes referred to as "PAM-E"), 9,9-bis(4-aminophenyl)fluorene, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzoylaniline, m-phenylenediamine, and 4,4'-oxodiphenylene. Amines, 3,4'-oxodiphenylamine, N,N'-bis(4-aminophenyl)terephthalamide, meta-toluidine, o-toluidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexaneamine), and their derivatives, which may be used alone or in combination.

[0081] To improve the adhesion between the obtained polyimide film and the substrate, PAM-E is preferably used as the diamine (monomer). To further improve the adhesion between the obtained polyimide film and the substrate, the content of PAM-E residues is preferably 0.01 mol% or more and 1 mol% or less relative to all diamine residues constituting the specific polyamic acid (100 mol%).

[0082] In order to improve the adhesion between the polyimide film and the substrate in high-temperature processes by suppressing the generation of hydrogen fluoride in a high-temperature atmosphere, the content of fluorine atoms in a specific polyamic acid is preferably less than 5% by mass, more preferably less than 1% by mass, and even more preferably less than 0.5% by mass relative to the total amount (100% by mass) of the specific polyamic acid.

[0083] The weight-average molecular weight of a particular polyamic acid also depends on its application, preferably in the range of 10,000 or more and 1,000,000 or less, more preferably in the range of 20,000 or more and 500,000 or less, and even more preferably in the range of 30,000 or more and 200,000 or less. If the weight-average molecular weight is 10,000 or more, the viscosity of the polyamic acid composition can be easily adjusted to a range suitable for coating (e.g., 0.5 Pa·s or more and 10 Pa·s or less). On the other hand, if the weight-average molecular weight is 1,000,000 or less, it exhibits sufficient solubility in solvents, thus allowing the use of the polyamic acid composition to obtain a coated film or polyimide film with a smooth surface and uniform thickness. The weight-average molecular weight used herein refers to the polyethylene oxide equivalent value determined using gel permeation chromatography (GPC).

[0084] In addition, in order to shorten the heating time and improve the properties, the polyamic acid composition of this embodiment may also contain an imidization accelerator and / or a dehydration catalyst.

[0085] There are no particular limitations on the imidization promoters described above, and tertiary amines can be used. Heterocyclic tertiary amines are preferred. Specific examples of preferred heterocyclic tertiary amines include pyridine, methylpyridine, quinoline, isoquinoline, and imidazoles. Specific examples of preferred dehydration catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, and trifluoroacetic anhydride.

[0086] From the viewpoints of shortening heating time and exhibiting good properties, the amount of imidization accelerator relative to 100 parts by weight of a specific polyamic acid is preferably 0.1 parts by weight or more and 20 parts by weight or less, more preferably 0.5 parts by weight or more and 20 parts by weight or less. Furthermore, from the viewpoints of shortening heating time and exhibiting good properties, the amount of dehydration catalyst relative to 100 parts by weight of a specific polyamic acid is preferably 0.1 parts by weight or more and 10 parts by weight or less, more preferably 0.5 parts by weight or more and 5 parts by weight or less.

[0087] Imidazoles are preferred as imidization accelerators. It should be noted that, in this specification, imidazoles refer to compounds having a 1,3-diazole ring (1,3-diazole ring structure). There are no particular limitations on the imidazoles that can be added to the polyamic acid composition of this embodiment; examples include: 1H-imidazolium, 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecanylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, etc. Among these, 1,2-dimethylimidazolium, 1-benzyl-2-methylimidazolium, and 1-benzyl-2-phenylimidazolium are preferred, and 1,2-dimethylimidazolium and 1-benzyl-2-methylimidazolium are more preferred.

[0088] Relative to 1 mole of the amide group in a specific polyamic acid, the content of imidazole is preferably 0.005 moles or more and 0.1 moles or less, more preferably 0.01 moles or more and 0.08 moles or less, and even more preferably 0.015 moles or more and 0.050 moles or less. By containing 0.005 moles or more of imidazole, the film strength and transparency of the polyimide can be improved. By setting the imidazole content to 0.1 moles or less, the storage stability of the specific polyamic acid can be maintained, and the heat resistance can be improved. It should be noted that, in this specification, "amide group of the specific polyamic acid" refers to the amide group generated through the polymerization reaction of a diamine and a tetracarboxylic dianhydride.

[0089] There are no particular limitations on the method of mixing the specific polyamic acid with imidazoles. From the viewpoint of ease of controlling the molecular weight of the specific polyamic acid, it is preferable to add imidazoles to the polymerized specific polyamic acid. At this time, the imidazoles can be added directly to the specific polyamic acid, or the imidazoles can be dissolved in a solvent beforehand and the solution can be added to the specific polyamic acid; there are no particular limitations on the method of addition. The polyamic acid composition of this embodiment can also be prepared by adding imidazoles to the polymerized solution containing the specific polyamic acid (the solution after reaction).

[0090] In the polyamic acid composition of this embodiment, various organic or inorganic low-molecular-weight compounds or high-molecular-weight compounds may also be incorporated as additives. Examples of additives include plasticizers, antioxidants, dyes, surfactants, leveling agents, organosilicones, microparticles, and sensitizers. Microparticles include organic microparticles formed from polystyrene, polytetrafluoroethylene, etc., and inorganic microparticles formed from colloidal silica, carbon, layered silicates, etc., which may have porous or hollow structures. Furthermore, the function and morphology of the microparticles are not particularly limited; for example, they may be pigments, fillers, or fibrous particles.

[0091] In addition, to exhibit proper adhesion to the support, the polyamic acid composition of this embodiment may contain a silane coupling agent. Known silane coupling agents can be used without particular limitation. To exhibit good adhesion to the support, compounds containing amino groups are preferred as usable silane coupling agents; more preferably, one or more compounds selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-(ethoxydimethylsilyl)propylamine, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane are preferred; even more preferably, one or more compounds selected from the group consisting of 3-aminopropyltriethoxysilane and 3-aminopropyldiethoxymethylsilane are preferred; and 3-aminopropyltriethoxysilane is particularly preferred.

[0092] The mixing ratio of the silane coupling agent to 100 parts by weight of a specific polyamic acid is preferably 0.01 parts by weight or more and 0.50 parts by weight or less, more preferably 0.01 parts by weight or more and 0.30 parts by weight or less, and even more preferably 0.01 parts by weight or more and 0.20 parts by weight or less. By setting the mixing ratio of the silane coupling agent to 0.01 parts by weight or more, the peeling inhibition effect on the support can be fully utilized. By setting the mixing ratio of the silane coupling agent to 0.50 parts by weight or less, the decrease in molecular weight of the specific polyamic acid can be suppressed, thereby suppressing the embrittlement of the polyimide film.

[0093] In order to obtain polyimide with further reduced internal stress and further improved transparency, the polyamic acid composition of this embodiment preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and even more preferably satisfies the following condition 3.

[0094] Condition 1: The specific polyamic acid has one or more residues selected from the group consisting of s-BPDA residues, a-BPDA residues, SFDA residues, BPAF residues and ODPA residues, and the content of one or more residues selected from the group consisting of s-BPDA residues, a-BPDA residues, SFDA residues, BPAF residues and ODPA residues is more than 80 mol% and less than 100 mol% relative to all tetracarboxylic dianhydride residues (100 mol%) constituting the specific polyamic acid.

[0095] Condition 2: The above condition 1 is met, and the content of 4-BAAB residues is more than 80 mol% and less than 100 mol% relative to all diamine residues (100 mol%) constituting the specific polyamic acid.

[0096] Condition 3: The above condition 2 is met, and the Gardner color of the polyamic acid composition and the APAH of the polyamic acid composition are 0.3 or less and 10 or less, respectively.

[0097] The method for manufacturing the polyamic acid composition of this embodiment includes a step S1 of reacting a diamine with a tetracarboxylic acid dianhydride in an organic solvent. In addition to satisfying conditions A to F as shown below, the method for reacting the diamine with the tetracarboxylic acid dianhydride in an organic solvent can also employ known conventional methods. The specific method for reacting the diamine with the tetracarboxylic acid dianhydride in an organic solvent is described below.

[0098] Condition A: Use at least 4-BAAB as the diamine (monomer).

[0099] Condition B: The content of 4-BAAB in the diamine (monomer) is more than 70 mol% relative to the total amount of diamine (100 mol%).

[0100] Condition C: 4-BAAB is supplied as a raw material (4-BAAB composition) containing impurities in process S1.

[0101] Condition D: Impurities in the 4-BAAB composition include aminophenol and methyl aminobenzoate.

[0102] Condition E: The Gardner colorimetry measured in a cuvette with an optical path length of 1 cm using a 1% NMP solution of the 4-BAAB composition is below 3.0.

[0103] Condition F: The APAH value measured in a cuvette with an optical path length of 1 cm using a 1% NMP solution of the 4-BAAB composition is below 200.

[0104] By satisfying conditions A to F above, the polyamic acid composition of this embodiment can be easily manufactured.

[0105] Hereinafter, the Gardner colorimetry measured using a 1% NMP solution of the 4-BAAB composition in a cuvette with a 1 cm optical path length will sometimes be abbreviated as "Gardner colorimetry of the 4-BAAB composition". Additionally, the APAH measured using a 1% NMP solution of the 4-BAAB composition in a cuvette with a 1 cm optical path length will sometimes be abbreviated as "APAH of the 4-BAAB composition". The methods for determining the Gardner colorimetry and APAH of the 4-BAAB composition are the same as or based on the methods described in the examples below. There is a tendency that the lower the content of aminophenol and methyl aminobenzoate in the 4-BAAB composition, the lower the Gardner colorimetry and APAH of the 4-BAAB composition. There are no lower limits for the Gardner colorimetry and APAH of the 4-BAAB composition; both can be 0.

[0106] In order to obtain polyimide with further reduced internal stress and better transparency, the manufacturing method of the polyamic acid composition of this embodiment preferably satisfies conditions G and H as shown below.

[0107] Condition G: The content of aminophenol in the 4-BAAB composition is less than 0.60% by mass relative to the total amount of 4-BAAB (100% by mass).

[0108] Condition H: The content of methyl aminobenzoate in the 4-BAAB composition is less than 0.60% by mass relative to the total amount of 4-BAAB (100% by mass).

[0109] Hereinafter, the content of aminophenol in the 4-BAAB composition relative to the total amount of 4-BAAB is sometimes abbreviated as "content of aminophenol in the 4-BAAB composition". Additionally, the content of methyl aminobenzoate in the 4-BAAB composition relative to the total amount of 4-BAAB is sometimes abbreviated as "content of methyl aminobenzoate in the 4-BAAB composition". The methods for determining both "content of aminophenol in the 4-BAAB composition" and "content of methyl aminobenzoate in the 4-BAAB composition" are the same as or based on the methods described in the examples below.

[0110] To obtain a polyimide with further reduced internal stress and improved transparency, the aminophenol content in the 4-BAAB composition is preferably 0.05% by mass or more and 0.60% by mass or less, more preferably 0.10% by mass or more and 0.58% by mass or less, and even more preferably 0.15% by mass or more and 0.56% by mass or less.

[0111] In order to obtain polyimide with further reduced internal stress and further improved transparency, the content of methyl aminobenzoate in the 4-BAAB composition is preferably 0.01% by mass or more and 0.60% by mass or less, more preferably 0.02% by mass or more and 0.40% by mass or less, and even more preferably 0.03% by mass or more and 0.20% by mass or less.

[0112] To obtain a polyimide with further reduced internal stress and improved transparency, the content of ethyl aminobenzoate in the 4-BAAB composition relative to the total amount of 4-BAAB (100% by mass) is preferably 0.15% by mass or less, more preferably 0.01% by mass or more and 0.15% by mass or less, even more preferably 0.02% by mass or more and 0.10% by mass or less, and particularly preferably 0.02% by mass or more and 0.05% by mass or less.

[0113] An example of a method (synthetic method) for reacting a diamine with a tetracarboxylic dianhydride in an organic solvent will be described. First, as a first method, a diamine solution is prepared by dissolving the diamine in an organic solvent or dispersing it in a slurry form in an inert gas atmosphere such as argon or nitrogen. Then, the tetracarboxylic dianhydride is added to the diamine solution either in a dissolved state or in a slurry form, or in a solid state. Alternatively, as a second method, a tetracarboxylic dianhydride solution is prepared by dissolving the tetracarboxylic dianhydride in an organic solvent or dispersing it in a slurry form in an inert gas atmosphere such as argon or nitrogen. Then, the diamine is added to the tetracarboxylic dianhydride solution either in a dissolved state or in a slurry form, or in a solid state.

[0114] When synthesizing a specific polyamic acid using diamines and tetracarboxylic dianhydrides, the desired specific polyamic acid (a polymer of diamine and tetracarboxylic dianhydrides) can be obtained by adjusting the amount of diamine (or the amount of each diamine when using multiple diamines) and the amount of tetracarboxylic dianhydrides (or the amount of each tetracarboxylic dianhydride when using multiple tetracarboxylic dianhydrides). The molar fraction of each residue in the specific polyamic acid is, for example, consistent with the molar fraction of each monomer used in the synthesis of the specific polyamic acid (the molar fraction of each monomer corresponding to each residue). Alternatively, a specific polyamic acid containing multiple tetracarboxylic dianhydride residues and multiple diamine residues can also be obtained by blending two polyamic acids. The temperature conditions for the reaction of the diamine with the tetracarboxylic dianhydride, i.e., the synthesis reaction of the specific polyamic acid, are not particularly limited, but are, for example, in the range of 20°C to 150°C. The reaction time for the synthesis reaction of the specific polyamic acid is, for example, in the range of 10 minutes to 30 hours.

[0115] One method for controlling the molecular weight of a specific polyamic acid is to use an excess of either the dianhydride or the diamine; another method is to quench the reaction by reacting it with a monofunctional anhydride or amine such as phthalic anhydride or aniline. When polymerization is carried out with an excess of either the dianhydride or the diamine, a polyimide film with sufficient strength can be obtained if their molar ratio is between 0.95 and 1.05. It should be noted that the above molar ratio is the ratio of the total amount of diamine used in the synthesis of the specific polyamic acid to the total amount of dianhydride used in the synthesis of the specific polyamic acid (total amount of diamine / total amount of dianhydride). Furthermore, by using phthalic anhydride, maleic anhydride, aniline, etc. for end-capping, the coloring of the polyimide obtained using the specific polyamic acid can be further reduced.

[0116] The organic solvent used in the synthesis of a specific polyamic acid is preferably a solvent capable of dissolving the tetracarboxylic acid dianhydride and diamine used, and more preferably a solvent capable of dissolving the specific polyamic acid produced. Examples of organic solvents used in the synthesis of a specific polyamic acid include: urea solvents such as N,N-dimethylethylurea; sulfoxide solvents such as dimethyl sulfoxide; sulfone solvents such as tetramethyl sulfone; amide solvents such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), N-butyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide (MPA), and hexamethylphosphoric triamine; ester solvents such as γ-butyrolactone; haloalkyl solvents such as chloroform; aromatic hydrocarbon solvents such as toluene; phenolic solvents such as phenol; ketone solvents such as cyclopentanone; and ether solvents such as tetrahydrofuran. These solvents are usually used alone, but two or more can be used in combination as needed. The organic solvent used in the synthesis of a specific polyamic acid is preferably one or more solvents selected from the group consisting of amide solvents, ketone solvents, ester solvents, and ether solvents, and more preferably amide solvents (more specifically, DMF, DMAC, NMP, MPA, etc.). Furthermore, the synthesis reaction of the specific polyamic acid is preferably carried out under an inert gas atmosphere such as argon or nitrogen.

[0117] When obtaining a specific polyamic acid using the above method, the reaction solution (the solution after the reaction) itself can also be used as the polyamic acid composition of this embodiment. In this case, the organic solvent in the polyamic acid composition is the organic solvent used in the synthesis reaction. Alternatively, the specific polyamic acid obtained by removing the solvent from the reaction solution can be dissolved in an organic solvent to prepare the polyamic acid composition of this embodiment.

[0118] The concentration of a specific polyamic acid in the polyamic acid composition of this embodiment is not particularly limited, but is, for example, 5% or more and 40% or less relative to the total amount of the polyamic acid composition (100% by mass), preferably 8% or more and 30% or less by mass.

[0119] The polyimide of this embodiment is an imide of the specific polyamic acid described above. The polyimide of this embodiment can be obtained by known methods, and its manufacturing method is not particularly limited. Hereinafter, an example of a method for obtaining the polyimide of this embodiment by imidizing a specific polyamic acid will be described. Imidization is performed by dehydrating and ring-closing the specific polyamic acid. This dehydration and ring-closing can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Furthermore, the imidization from the specific polyamic acid to the polyimide can be performed in any proportion of 1% or more and 100% or less. That is, a portion of the imidized specific polyamic acid can be synthesized. Partially, when imidization is performed by heating, the ring-closing reaction from the specific polyamic acid to the polyimide occurs simultaneously with the hydrolysis of the specific polyamic acid. The molecular weight of the polyimide produced may be lower than the molecular weight of the specific polyamic acid. Therefore, from the viewpoint of improving mechanical properties, it is preferable to pre-imidize a portion of the specific polyamic acid in the polyamic acid composition before forming the polyimide film described later. In this specification, some imidized polyamic acids are sometimes also referred to as "polyamic acid".

[0120] The dehydration and ring-closure of a specific polyamic acid can be achieved simply by heating the specific polyamic acid. There are no particular limitations on the method of heating the specific polyamic acid; for example, after coating the polyamic acid composition of this embodiment onto a support such as a glass substrate, metal plate, or PET film (polyethylene terephthalate film), heat treatment of the specific polyamic acid can be performed at a temperature between 40°C and 500°C. According to this method, a laminate of this embodiment having a support and a polyimide film (specifically, a polyimide film containing an imide compound of the specific polyamic acid) disposed on the support can be obtained. Alternatively, the polyamic acid composition can be directly placed in a container that has undergone a demolding treatment such as coating with a fluorinated resin, and the polyamic acid composition can be heated and dried under reduced pressure to achieve the dehydration and ring-closure of the specific polyamic acid. Polyimides can be obtained by using these methods to achieve the dehydration and ring-closure of the specific polyamic acid. It should be noted that the heating time for each of the above treatments varies depending on the amount of polyamic acid composition to be dehydrated and closed-loop and the heating temperature. It is generally preferred to set the heating time to be more than 1 minute and less than 300 minutes after the treatment temperature reaches the maximum temperature.

[0121] The polyimide film of this embodiment (more specifically, a polyimide film containing an imide compound of a specific polyamic acid) is colorless and transparent with low yellowness and has a glass transition temperature (heat resistance) capable of withstanding TFT fabrication processes, thus making it suitable as a transparent substrate material for flexible displays. The content of polyimide (specifically, an imide compound of a specific polyamic acid) in the polyimide film of this embodiment is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and may also be 100% by mass, relative to the total amount of the polyimide film. Other components in the polyimide film besides polyimide include, for example, the aforementioned additives (more specifically, microparticles, etc.).

[0122] The electronic device (more specifically, a flexible device, etc.) of this embodiment has a polyimide film of this embodiment and electronic components disposed directly or indirectly on the polyimide film. In manufacturing the electronic device of this embodiment as a flexible display, firstly, an inorganic substrate such as glass is used as a support, and a polyimide film is formed on it. Then, electronic components such as TFTs are disposed (formed) on the polyimide film, thus forming the electronic device on the support. The TFT formation process is typically performed in a wide temperature range of 150°C to 650°C, but in practice, to achieve the desired performance, sometimes an oxide semiconductor layer or an a-Si layer is formed at 300°C or higher, and depending on the situation, the a-Si layer is further crystallized using a laser or the like.

[0123] At this point, if the thermal decomposition temperature of the polyimide film is low, exhaust gas may be generated during the formation of electronic components, which may adhere to the oven in the form of sublimation, causing contamination inside the oven. Alternatively, inorganic films (barrier films, etc., described later) formed on the polyimide film or electronic components may peel off. Therefore, the 1% weight loss temperature of the polyimide is preferably 500°C or higher. The higher the upper limit of the 1% weight loss temperature of the polyimide, the better, for example, 600°C. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues with rigid structures (more specifically, s-BPDA residues, etc.). More specifically, before TFT formation, inorganic films such as silicon oxide films (SiOx films) and silicon nitride films (SiNx films) are formed on the polyimide film as barrier films. At this point, if the polyimide has low heat resistance, imidization is incomplete, or there is a lot of residual solvent, the polyimide may peel off from the inorganic film during the high-temperature process after the inorganic film is laminated due to volatile components such as decomposition gases of the polyimide. Therefore, it is preferable that the polyimide film and the inorganic film do not peel off when the laminate after the inorganic film is formed is held at a temperature of 400°C for 1 hour. For TFTs, the higher the processing temperature, the higher the performance. Therefore, it is preferable that the polyimide film and the inorganic film do not peel off when the laminate after the inorganic film is formed is held at a temperature of 430°C for 1 hour, and it is even more preferable that the polyimide film and the inorganic film do not peel off when the laminate after the inorganic film is formed is held at a temperature of 470°C for 1 hour.

[0124] Furthermore, if the glass transition temperature (Tg) of polyimide is significantly lower than the process temperature, positional shifts may occur during the formation of electronic components. Therefore, the Tg of polyimide is preferably 400°C or higher, more preferably 420°C or higher, even more preferably 430°C or higher, and even more preferably 450°C or higher. A higher upper limit for the Tg of polyimide is preferable, for example, 500°C. Additionally, generally, the coefficient of thermal expansion of the glass substrate is smaller than that of the resin, thus generating internal stress between the glass substrate and the polyimide film. If the internal stress of the laminate containing the glass substrate used as a support, the electronic components, and the polyimide film is high, the laminate containing the polyimide film will expand during the high-temperature TFT formation process and then shrink upon cooling to room temperature, causing problems such as warping and breakage of the glass substrate, and peeling of the polyimide film from the glass substrate. Therefore, in the laminate having a glass substrate (support) and a polyimide film (the laminate of this embodiment), the internal stress between the polyimide film and the glass substrate is preferably 30 MPa or less, more preferably 20 MPa or less, and even more preferably 10 MPa or less. The lower the lower limit of the internal stress, the better; it can also be 0 MPa. The method for measuring the internal stress is the same as that described in the embodiments below or a method based on that method.

[0125] The polyimide of this embodiment is suitable for use as a material for display substrates such as TFT substrates and touch panel substrates. When using polyimide for the above-mentioned applications, the method described above is generally used: after forming electronic devices on a support (more specifically, electronic devices on which electronic components are formed on a polyimide film), the polyimide film is peeled off from the support. Furthermore, alkali-free glass is preferably used as the material for the support. Hereinafter, an example of a method for manufacturing a laminate of polyimide film and support will be described in detail.

[0126] First, the polyamic acid composition of this embodiment is coated (cast) onto a support to form a laminate containing a coated film, which is composed of a coated film containing a specific polyamic acid and a support. Next, the laminate containing the coated film is heated at a temperature of, for example, 40°C or higher and 200°C or lower. The heating time is, for example, 3 minutes or more and 120 minutes or less. It should be noted that a multi-stage heating process can be provided, such as heating the laminate containing the coated film at 50°C for 30 minutes, then at 100°C for 30 minutes, etc. Next, in order to promote the imidization of the specific polyamic acid in the coated film, the laminate containing the coated film is heated at a maximum temperature of, for example, 200°C or higher and 500°C or lower. The heating time (heating time at the maximum temperature) is, for example, 1 minute or more and 300 minutes or less. It is preferable to gradually increase the temperature from a low temperature to the maximum temperature. The heating rate is preferably 2°C / min or more and 10°C / min or less, more preferably 4°C / min or more and 10°C / min or less. Furthermore, the maximum temperature is preferably in the range of 250°C or more and 450°C or less. If the maximum temperature is 250°C or more, imidization is sufficiently carried out; if the maximum temperature is 450°C or less, thermal degradation and coloring of the polyimide can be suppressed. Alternatively, the temperature can be maintained at any temperature for any time before reaching the maximum temperature. The imidization reaction can be carried out in air, under reduced pressure, or in an inert gas such as nitrogen, but to exhibit higher transparency, it is preferable to carry it under reduced pressure or in an inert gas such as nitrogen. Additionally, known devices such as hot air ovens, infrared ovens, vacuum ovens, inert ovens, and heating plates can be used as heating devices. Through these processes, the specific polyamic acid in the coated film is imidized, resulting in a laminate of a support and a polyimide film (a film containing an imide of the specific polyamic acid) (i.e., the laminate of this embodiment).

[0127] Known methods can be used to peel the polyimide film from the obtained laminate of the support and the polyimide film. For example, it can be peeled by hand or by mechanical devices such as drive rollers or robots. Alternatively, a method can be used to provide a release layer between the support and the polyimide film, or a method can be used to peel the polyimide film by forming a silicon oxide film on a substrate with multiple grooves, using the silicon oxide film as a base layer to form the polyimide film, and then allowing an etching solution of silicon oxide to wet between the substrate and the silicon oxide film. Another method can be used to separate the polyimide film by laser irradiation.

[0128] The transparency of the polyimide film can be evaluated, for example, using the total transmittance (TT) according to JIS K7361-1:1997 and the haze according to JIS K7136-2000. When using a polyimide film in applications requiring high transparency, the total transmittance of the polyimide film is preferably 75% or more, more preferably 80% or more. Furthermore, when using a polyimide film in applications requiring high transparency, the haze of the polyimide film is preferably 1.5% or less, more preferably 1.2% or less, further preferably 1.0% or less, and can also be 0%. In applications requiring high transparency, the polyimide film is required to have high transmittance across the entire wavelength range; however, polyimide films tend to absorb light from shorter wavelengths, and the film itself is mostly colored yellow. To use polyimide films in applications requiring high transparency, it is preferable to reduce the coloring of the polyimide film. Specifically, for applications requiring high transparency, the yellowness (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, and can also be 0. YI can be measured according to JIS K7373-2006. YI can be adjusted, for example, by changing the content of aminophenol and methyl aminobenzoate in the polyamic acid composition. In this way, the polyimide film, with reduced coloration and improved transparency, is suitable for transparent substrates used as glass replacements, and substrates with sensors or camera modules mounted on the back side.

[0129] Furthermore, in applications requiring transparency, high transmittance of blue light (light with a wavelength around 470 nm) is particularly desirable from the viewpoint of color reproduction, and practically, high transmittance of light with a wavelength of 400 nm (400 nm transmittance) is required. From the viewpoint of color reproduction, the 400 nm transmittance of the polyimide film is preferably 8% or higher. There is no particular upper limit to the 400 nm transmittance of the polyimide film, and it can be 100%. The 400 nm transmittance can be adjusted, for example, by changing the content of aminophenol and methyl aminobenzoate in the polyamic acid composition.

[0130] Furthermore, in the light extraction methods of flexible displays, there are two types: top-emission, which extracts light from the surface side of the TFT, and bottom-emission, which extracts light from the back side of the TFT. In the top-emission method, since the light is not blocked by the TFT, it is easy to increase the aperture ratio and obtain high-resolution image quality. The bottom-emission method is easy to align the TFT and pixel electrodes and is easy to manufacture. If the TFT is transparent, the aperture ratio can be increased even in the bottom-emission method, so there is a tendency to use the easily manufactured bottom-emission method for large displays. The polyimide film of this embodiment has low YI and excellent heat resistance, so it can also be applied to either of the above-mentioned light extraction methods.

[0131] Furthermore, in intermittent device fabrication processes such as coating a polyamic acid composition onto a support like a glass substrate, heating it to imidize it, forming electronic components, and then peeling off the polyimide film, excellent adhesion between the support and the polyimide film is preferable. Here, adhesion refers to adhesion strength. In fabrication processes where electronic components are formed on the polyimide film on the support, and the polyimide film with the formed electronic components is peeled off from the support, excellent adhesion between the polyimide film and the support allows for more accurate formation or mounting of the electronic components. In manufacturing processes where electronic components are placed on the support with the polyimide film in between, from the viewpoint of improving productivity, higher peel strength between the support and the polyimide film is better. Specifically, the peel strength is preferably 0.05 N / cm or more, more preferably 0.1 N / cm or more.

[0132] In the manufacturing process described above, the polyimide film is usually peeled off from the support and polyimide film laminate by laser irradiation. In this case, the polyimide film needs to absorb the laser, therefore the cutoff wavelength of the polyimide film is required to be longer than the wavelength of the laser used for peeling. Laser peeling mostly uses XeCl excimer lasers with a wavelength of 308 nm, so the cutoff wavelength of the polyimide film is preferably 312 nm or more, more preferably 330 nm or more. On the other hand, if the cutoff wavelength is long, there is a tendency for the polyimide film to be colored yellow, so the cutoff wavelength of the polyimide film is preferably 390 nm or less. From the viewpoint of balancing transparency (low yellowness) and processability of laser peeling, the cutoff wavelength of the polyimide film is preferably 320 nm or more and 390 nm or less, more preferably 330 nm or more and 390 nm or less. It should be noted that the cutoff wavelength in this specification refers to the wavelength with a transmittance of 0.1% or less as measured by a UV-Vis spectrophotometer.

[0133] The polyamic acid composition and polyimide of this embodiment can be used directly in coating or molding processes for manufacturing articles or components, or as materials for further coating or other treatments on molded articles formed into thin films. For use in coating or molding processes, the polyamic acid composition or polyimide can be dissolved or dispersed in an organic solvent as needed, and then mixed with photocurable components, thermocurable components, non-polymerizable adhesive resins, and other components as needed to prepare a composition containing a specific polyamic acid or polyimide.

[0134] Various inorganic thin films, such as metal oxide films and transparent electrodes, can also be formed on the surface of the polyimide film in this embodiment. There are no particular limitations on the methods for forming these inorganic thin films; examples include sputtering, vacuum evaporation, ion plating, and other PVD and CVD methods.

[0135] In addition to its heat resistance, low thermal expansion, and transparency, the polyimide film of this embodiment exhibits low internal stress when laminated with a glass substrate, ensuring excellent adhesion to inorganic materials during high-temperature processes. Therefore, it is preferably used in fields and products where these properties are considered effective. For example, the polyimide film of this embodiment is preferably used in image display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as printed materials, color filters, flexible displays, optical thin films, 3D displays, touch panels, transparent conductive film substrates, and solar cells, and is even more preferably used as a replacement material for parts currently using glass. In these applications, the thickness of the polyimide film is, for example, 1 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less. The thickness of the polyimide film can be measured using a laser hologram.

[0136] Furthermore, the polyamic acid composition of this embodiment can be suitably used in a method for manufacturing a polyimide film in which the polyamic acid composition is coated onto a support, imidized by heating, and then the polyimide film is peeled off from the support. Additionally, the polyamic acid composition of this embodiment can be suitably used in an intermittent device fabrication process in which the polyamic acid composition is coated onto a support, imidized by heating, electronic components or the like are formed on the resulting polyimide film, and then the polyimide film with the electronic components or the like is peeled off from the support. Therefore, this embodiment also includes a method for manufacturing an electronic device comprising the steps of coating a polyamic acid composition onto a support, imidizing by heating, and forming electronic components or the like on a polyimide film formed on a support. Furthermore, this method for manufacturing an electronic device may also include a step of peeling off the polyimide film with the electronic components or the like from the support.

[0137] Example

[0138] The following describes embodiments of the present invention, but the scope of the present invention is not limited to the following embodiments. It should be noted that, hereinafter, compounds and reagents are referred to by the following abbreviations.

[0139] NMP: N-methyl-2-pyrrolidone

[0140] s-BPDA: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride

[0141] a-BPDA: 2,3,3',4'-Biphenyltetracarboxylic acid dianhydride

[0142] SFDA: Spiro[11H-difuran[3,4-b:3',4'-i]xanton-11,9'-[9H]fluorene]-1,3,7,9-tetraone

[0143] BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorene dihydride

[0144] ODPA: 4,4'-O-diphthalic anhydride

[0145] 4-BAAB: 4-Aminobenzoic acid, 4-aminophenyl ester

[0146] <Methods for Determining Physical Properties>

[0147] First, the methods for determining the physical properties of the 4-BAAB composition, the polyamic acid composition, and the polyimide (polyimide film) are explained.

[0148] Gardner Chroma

[0149] First, using a petroleum product colorimeter (NECOLOR OME-2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.), based on ISO 4630, the Gardner colorimetry of distilled water was measured in a cuvette with a 1 cm optical path length, and the measured value was confirmed to be 0.0. Next, the Gardner colorimetry of each sample (a 1% NMP solution of each 4-BAAB composition, or each polyamic acid composition diluted with NMP to a 1% NMP concentration of polyamic acid) was measured using the same method as for distilled water. It should be noted that the Gardner colorimetry of the NMP itself was measured using the same method as for distilled water, and the Gardner colorimetry of the NMP was confirmed to be 0.0.

[0150] [APAH]

[0151] First, using a petroleum product colorimetric tester (NEDS "OME-2000" manufactured by Nippon Denshoku Kogyo Co., Ltd.), based on ISO 2211, the APAH of distilled water was measured in a cuvette with a 1 cm optical path length, and the measured value was confirmed to be 0. Next, the APAH of each sample (a 1% NMP solution of each 4-BAAB composition, or each polyamic acid composition diluted with NMP to a 1% NMP concentration) was measured using the same method as for distilled water. It should be noted that the APAH of the NMP itself was measured using the same method as for distilled water, and the APAH of the NMP was confirmed to be 0.

[0152] [Internal Stress]

[0153] On a Corning glass substrate (trade name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) manufactured by Corning (warpage pre-measured), the polyamic acid compositions prepared in the examples and comparative examples described below were coated using a spin coater. After heating in air at 120°C for 30 minutes, the substrate was then heated at 430°C for 30 minutes under a nitrogen atmosphere to obtain a laminate with a 10 μm thick polyimide film on the glass substrate. To eliminate the influence of water absorption by the polyimide film, the laminate was dried at 120°C for 10 minutes, and the warpage of the laminate under a nitrogen atmosphere at 25°C was measured using a thin film stress measuring device (KLA-Tencor "FLX-2320-S"). Then, based on the warpage of the glass substrate before polyimide film formation and the warpage of the laminate, the internal stress generated between the glass substrate and the polyimide film was calculated using the Stony formula. When the internal stress is below 30 MPa, it is evaluated as "able to reduce internal stress". On the other hand, when the internal stress exceeds 30 MPa, it is evaluated as "unable to reduce internal stress".

[0154] [Yellowness (YI)]

[0155] For the polyimide films in each laminate obtained in the examples and comparative examples described later, the transmittance of light with wavelengths of 200 nm and above to 800 nm was measured using a UV-Vis-NIR spectrophotometer (Nippon Spectrophotometer, "V-650"). The yellowness (YI) of the polyimide film was calculated according to the formula described in JIS K7373-2006. When YI is 20 or below, it is evaluated as "excellent transparency". On the other hand, when YI is above 20, it is evaluated as "not excellent transparency".

[0156] [400nm transmittance and 450nm transmittance]

[0157] For the polyimide films in each laminate obtained in the examples and comparative examples described later, the transmittance of light at a wavelength of 400 nm (400 nm transmittance) and the transmittance of light at a wavelength of 450 nm (450 nm transmittance) were measured using a UV-Vis-NIR spectrophotometer (V-650 manufactured by Nippon Spectrophotometer Co., Ltd.).

[0158] [GC / MS Analysis of 4-BAAB Composition]

[0159] For each sample (a 1% NMP solution of each 4-BAAB composition), GC / MS analysis was performed using a GC / MS analytical apparatus combining a gas chromatograph (Agilent Technologies "6890N") and a mass spectrometer (Agilent Technologies "5975inert"), under the following conditions. Based on the obtained GC / MS spectra, the area S1 of the peak with a retention time (RT) of 11.405–11.603 min (derived from aminophenol), the area S2 of the peak with a RT of 13.196–13.256 min (derived from methyl aminobenzoate), the area S3 of the peak with a RT of 13.652–13.704 min (derived from ethyl aminobenzoate), and the area S4 of the peak with a RT of 18.303–18.803 min (derived from 4-BAAB) were calculated. Then, the content of aminophenol in the 4-BAAB composition (in mass%) is calculated based on the formula "100×S1 / S4", the content of methyl aminobenzoate in the 4-BAAB composition (in mass%) is calculated based on the formula "100×S2 / S4", and the content of ethyl aminobenzoate in the 4-BAAB composition (in mass%) is calculated based on the formula "100×S3 / S4".

[0160] (Conditions for GC / MS analysis)

[0161] Column: DB-5MS manufactured by Agilent Technologies (0.25mm ID × 30m, film thickness 0.25μm)

[0162] Carrier gas: Helium (1 mL / min)

[0163] Oven temperature: Set to 40℃, increase to 320℃ at a rate of 20℃ / minute.

[0164] Inlet temperature: 280℃

[0165] Interface temperature: 280℃

[0166] Ionization chamber temperature: 250℃

[0167] EM voltage: 1500eV

[0168] Measurement range: m / z = 29~800

[0169] Injected sample: 2 w / v acetonitrile solution of the sample (1 wt% NMP solution of 4-BAAB composition) (acetonitrile solution containing 2 g of sample in a total volume of 100 mL).

[0170] Sample injection volume: 1 μL

[0171] [GC / MS Analysis of Polyamic Acid Compositions]

[0172] For each sample (each polyamic acid composition diluted with NMP to a polyamic acid concentration of 1% by mass), a 2 w / v acetonitrile solution diluted with NMP to a polyamic acid concentration of 1% by mass was used as the injected sample. Otherwise, GC / MS analysis of each polyamic acid composition was performed using the same method as described above for [GC / MS analysis of 4-BAAB compositions]. The content of each impurity relative to the total amount of each sample was calculated (unit: ppm by mass) based on the peak area values ​​of the obtained GC / MS spectra.

[0173] <Preparation method of 4-BAAB composition>

[0174] The preparation methods of the 4-BAAB compositions M1 to M7 used in the examples and comparative examples are described below. It should be noted that the 4-nitrobenzoic acid 4-nitrophenyl ester, the starting material, is synthesized by the method shown below.

[0175] [Synthetic method of 4-nitrobenzene 4-nitrobenzoic acid]

[0176] In a round three-necked flask, 14 g of 4-nitrophenol (manufactured by Tokyo Chemical Industry Co., Ltd., "NO220") was dissolved in 300 mL of methyl ethyl ketone, and then 15.5 mL of triethylamine was added to obtain solution S. ph Additionally, 18.6 g of 4-nitrobenzyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd., "N0176") was dissolved in 150 mL of 1,4-dioxane to obtain solution S. be Next, the solution S in the flask... ph After cooling to 0°C, stir the solution S. ph One side takes 1 hour to add solution S ph Add solution S dropwise beNext, under an atmosphere at 23°C, the contents of the flask were stirred for 3 hours, and the precipitated salt was filtered off to obtain a homogeneous solution. Then, the solvent was removed from the obtained solution by distillation using an evaporator to obtain a powder. The obtained powder was then washed twice with a 5% (w / w) sodium bicarbonate aqueous solution, followed by two washes with distilled water. It was then dried under reduced pressure at 80°C for 12 hours to obtain 4-nitrobenzene 4-nitrobenzene acid.

[0177] [Preparation of 4-BAAB composition M7]

[0178] In a round three-necked flask, 15 g of FeSO4 heptahydrate, 30 g of methanol, and 30 g of distilled water were added. After stirring the contents of the flask, 5 g of 4-nitrobenzoic acid (4-nitrophenyl ester) was added. Then, under an atmosphere of 100°C, the contents of the flask were refluxed while stirring for 30 minutes. Next, 25 g of KOH (potassium hydroxide) was added to the flask, and the contents were stirred further for 30 minutes. The contents of the flask were then transferred to a separatory funnel, and 100 g of toluene was added to the funnel to extract the organic layer. This operation was repeated three times. After the toluene in the obtained organic layer was evaporated, the mixture was dried under reduced pressure at 70°C for 12 hours to obtain powder P1. Powder P1 was recrystallized using a mixed solvent of chloroform and ethanol (mass ratio: chloroform / ethanol = 70 / 30). The precipitate was then washed with ethanol and dried under reduced pressure at 70°C for 12 hours to obtain 4-BAAB composition M7.

[0179] [Preparation of 4-BAAB composition M5]

[0180] After obtaining powder P1 using the same method as described above for [Preparation of 4-BAAB Composition M7], the powder P1 was dissolved in dimethylacetamide in a round three-necked flask. Next, a small amount of activated carbon was added to the resulting dimethylacetamide solution (solid content concentration: 10% by mass), and the contents of the flask were stirred for 3 hours under an atmosphere at 50°C. Then, after filtering the activated carbon from the contents of the flask, the solvent was removed by distillation from the resulting dimethylacetamide solution, and the solution was dried under reduced pressure at 70°C for 12 hours to obtain 4-BAAB composition M5.

[0181] [Preparation of 4-BAAB composition M6]

[0182] The 4-BAAB composition M5 obtained in the above steps was recrystallized using a mixed solvent of chloroform and ethanol (mass ratio: chloroform / ethanol = 70 / 30). The resulting precipitate was then washed with ethanol and dried under reduced pressure at 70°C for 12 hours to obtain the 4-BAAB composition M6.

[0183] [Preparation of 4-BAAB composition M4]

[0184] 4-Nitrobenzoic acid (4-nitrophenyl ester) was dissolved in dimethylacetamide in a round three-necked flask. Then, a small amount of activated carbon was added to the resulting dimethylacetamide solution (solid concentration: 10% by mass), and the contents of the flask were stirred for 3 hours at 50°C. Next, the activated carbon was filtered out from the flask contents, and the solvent was removed by distillation from the resulting dimethylacetamide solution. The solution was then dried under reduced pressure at 70°C for 12 hours to obtain powder P2. Next, 15 g of FeSO4 heptahydrate, 30 g of methanol, and 30 g of distilled water were added to a round three-necked flask. After stirring the contents of the flask, 5 g of powder P2 was added to the flask. Then, under an atmosphere of 100°C, the contents of the flask were refluxed while stirring for 30 minutes. Finally, 25 g of KOH (potassium hydroxide) was added to the flask, and the contents of the flask were stirred further for 30 minutes. Next, the contents of the flask were transferred into a separatory funnel, and 100g of toluene was added to the funnel. The organic layer was extracted, and this operation was repeated three times. After the toluene in the obtained organic layer was evaporated, it was dried under reduced pressure at 70°C for 12 hours to obtain the 4-BAAB composition M4.

[0185] [Preparation of 4-BAAB composition M3]

[0186] The 4-BAAB composition M4 obtained in the above steps was recrystallized using a mixed solvent of chloroform and ethanol (mass ratio: chloroform / ethanol = 70 / 30). The resulting precipitate was then washed with ethanol and dried under reduced pressure at 70°C for 12 hours to obtain the 4-BAAB composition M3.

[0187] [Preparation of 4-BAAB composition M2]

[0188] 4-Nitrophenyl benzoate was recrystallized using a mixed solvent of chloroform and ethanol (mass ratio: chloroform / ethanol = 70 / 30). The precipitate was then washed with ethanol and dried under reduced pressure at 70°C for 12 hours to obtain powder P3. Powder P3 was then dissolved in dimethylacetamide in a round three-necked flask. A small amount of activated carbon was added to the resulting dimethylacetamide solution (solid concentration: 10% by mass), and the contents of the flask were stirred for 3 hours at 50°C. The activated carbon was then filtered out from the flask contents, and the solvent was removed by distillation from the resulting dimethylacetamide solution. The solution was then dried under reduced pressure at 70°C for 12 hours to obtain powder P4. 15 g of FeSO4 heptahydrate, 30 g of methanol, and 30 g of distilled water were added to a round three-necked flask. After stirring the contents of the flask, 5 g of powder P4 was added to the flask. Next, under an atmosphere of 100°C, the contents of the flask were refluxed while stirring for 30 minutes. Then, 25g of KOH (potassium hydroxide) was added to the flask, and the contents were stirred further for 30 minutes. The contents were then transferred to a separatory funnel, and 100g of toluene was added to the funnel to extract the organic layer. This operation was repeated three times. After the toluene in the obtained organic layer was evaporated, the mixture was dried under reduced pressure at 70°C for 12 hours to obtain the 4-BAAB composition M2.

[0189] [Preparation of 4-BAAB composition M1]

[0190] 4-Nitrobenzoic acid (4-nitrophenyl ester) was dissolved in dimethylacetamide in a round three-necked flask. A small amount of activated carbon was then added to the resulting dimethylacetamide solution (solid content concentration: 10% by mass), and the contents of the flask were stirred for 3 hours at 50°C. The activated carbon was then filtered out from the flask contents, and the solvent was removed by distillation from the resulting dimethylacetamide solution. The solution was then dried under reduced pressure at 70°C for 12 hours to obtain powder P5. Powder P5 was then recrystallized using a mixed solvent of chloroform and ethanol (mass ratio: chloroform / ethanol = 70 / 30). The precipitate was then washed with ethanol and dried under reduced pressure at 70°C for 12 hours to obtain powder P6. 15 g of FeSO4 heptahydrate, 30 g of methanol, and 30 g of distilled water were added to a round three-necked flask. After stirring the contents of the flask, 5 g of powder P6 was added to the flask. Next, under an atmosphere of 100°C, the contents of the flask were refluxed while stirring for 30 minutes. Then, 25g of KOH (potassium hydroxide) was added to the flask, and the contents were stirred further for 30 minutes. The contents were then transferred to a separatory funnel, and 100g of toluene was added to the funnel to extract the organic layer. This operation was repeated three times. After the toluene in the obtained organic layer was evaporated, the mixture was dried under reduced pressure at 70°C for 12 hours to obtain the 4-BAAB composition M1.

[0191] For 4-BAAB compositions M1 to M7, the Gardner color, APAH, content of aminophenol in the 4-BAAB composition, content of methyl aminobenzoate in the 4-BAAB composition, and content of ethyl aminobenzoate in the 4-BAAB composition are shown in Table 1.

[0192] [Table 1]

[0193]

[0194] <Fabrication of Polyimide Film>

[0195] The following describes the methods for manufacturing the polyimide films (laminates) of the examples and comparative examples. It should be noted that the preparation of the polyamic acid compositions used in the manufacturing of the polyimide films was carried out under a nitrogen atmosphere.

[0196] [Example 1]

[0197] 56.6 g of NMP was added as the organic solvent for polymerization to a 300 mL glass flask equipped with a stirrer with a stainless steel stirring rod and a nitrogen inlet tube. Next, while stirring the contents of the flask, 4.393 g of the 4-BAAB composition M1 was added to the flask and dissolved. Then, 5.607 g of s-BPDA was added to the contents of the flask, and the contents were stirred for 24 hours at 23°C to obtain a polyamic acid composition. The obtained polyamic acid composition was coated onto a Corning glass substrate (trade name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater. After heating in air at 80°C for 30 minutes, it was heated at 430°C for 30 minutes under a nitrogen atmosphere to obtain a laminate with a 10 μm thick polyimide film on the glass substrate (the laminate of Example 1).

[0198] [Examples 2-7 and Comparative Examples 1-6]

[0199] As shown in Table 2, the types and proportions of the dianhydrides used, as well as the types and proportions of the 4-BAAB composition used, were varied. Otherwise, the laminates of Examples 2-7 and Comparative Examples 1-6 were obtained using the same method as in Example 1. It should be noted that in Examples 2-7 and Comparative Examples 1-6, the total amount of dianhydrides used in preparing the polyamic acid compositions was the same as the total amount of dianhydrides used in preparing the polyamic acid compositions in Example 1.

[0200] Regarding Examples 1-7 and Comparative Examples 1-6, the types and proportions of the acid dianhydrides used, and the types and proportions of the 4-BAAB compositions used are shown in Table 2. Furthermore, regarding Examples 1-7 and Comparative Examples 1-6, the Gardner color of the polyamic acid compositions used, the APAH of the polyamic acid compositions used, the content of aminophenol in the polyamic acid compositions used, the content of methyl aminobenzoate in the polyamic acid compositions used, the content of ethyl aminobenzoate in the polyamic acid compositions used, the YI of the polyimide film, the 400nm and 450nm transmittance of the polyimide film, and the internal stress are shown in Table 3.

[0201] It should be noted that in Table 2, "-" indicates that the component was not used. Similarly, in Table 3, "-" indicates that it was not measured. Furthermore, in Table 2, the values ​​in the "Acid Dihydric Anhydride" column represent the content (in mol%) of each acid dianhydride relative to the total amount (100 mol%) of the acid dianhydride used. Additionally, in Table 2, the values ​​in the "4-BAAB Composition" column represent the feed ratio (in mol%) of 4-BAAB in the 4-BAAB composition relative to the total amount (100 mol%) of the acid dianhydride used. Furthermore, for any of Examples 1-7 and Comparative Examples 1-6, the molar fraction of each residue of polyamic acid in the prepared polyamic acid composition is consistent with the molar fraction of each monomer (corresponding to each residue) used in the synthesis of polyamic acid.

[0202] [Table 2]

[0203]

[0204] [Table 3]

[0205]

[0206] In Examples 1-7, the content of 4-BAAB residues in the polyamic acid compositions used was 70 mol% or more relative to all diamine residues constituting the polyamic acid. As shown in Table 3, in Examples 1-7, the content of aminophenol in the polyamic acid compositions used was 1 ppm or more and 30 ppm or less by mass. In Examples 1-7, the content of methyl aminobenzoate in the polyamic acid compositions used was 0.01 ppm or more and 0.10 ppm or less by mass.

[0207] As shown in Table 3, in Examples 1-7, YI was 20 or less. Therefore, the polyimide films obtained in Examples 1-7 exhibited excellent transparency. In Examples 1-7, the internal stress was 30 MPa or less. Therefore, the laminates obtained in Examples 1-7 could reduce internal stress.

[0208] As shown in Table 3, in Comparative Examples 3-6, the content of aminophenol in the polyamic acid compositions used exceeded 30 ppm by mass. In Comparative Examples 1 and 2, the content of methyl aminobenzoate in the polyamic acid compositions used exceeded 0.10 ppm by mass.

[0209] As shown in Table 3, in Comparative Examples 1-6, YI exceeds 20. Therefore, the transparency of the polyimide films obtained in Comparative Examples 1-6 is not excellent.

[0210] The results above indicate that, according to the present invention, a polyamic acid composition can be provided that can manufacture polyimides with reduced internal stress and excellent transparency.

Claims

1. A polyamic acid composition comprising polyamic acid, an organic solvent, aminophenol, and methyl aminobenzoate. The polyamic acid has a 4-aminobenzoic acid 4-aminophenyl ester residue as a diamine residue. The content of the 4-aminobenzoic acid 4-aminophenyl ester residue is more than 70 mol% relative to all diamine residues constituting the polyamic acid. Using a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass, the content of aminophenol, as determined by gas chromatography-mass spectrometry, is 1 ppm or more and 30 ppm or less relative to the total amount of the sample. Using a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass, the content of methyl aminobenzoate obtained by gas chromatography-mass spectrometry is 0.01 ppm by mass or more and 0.10 ppm by mass relative to the total amount of the sample.

2. The polyamic acid composition according to claim 1, wherein, Using a sample obtained by diluting the polyamic acid composition to a concentration of 1% by mass, the Gardner colorimetry and Hassen colorimetry measured in a cuvette with an optical path length of 1 cm were less than 0.3 and less than 10, respectively.

3. The polyamic acid composition according to claim 1, wherein, The polyamic acid has one or more of the following as tetracarboxylic acid dianhydride residues: a tetravalent organic group selected from the group consisting of a tetravalent organic group represented by chemical formula (1), a tetravalent organic group represented by chemical formula (2), a tetravalent organic group represented by chemical formula (3), a tetravalent organic group represented by chemical formula (4), a tetravalent organic group represented by chemical formula (5), a tetravalent organic group represented by chemical formula (6), a tetravalent organic group represented by chemical formula (7), a tetravalent organic group represented by chemical formula (8), a tetravalent organic group represented by chemical formula (9), and a tetravalent organic group represented by chemical formula (10). 。 4. A polyimide, which is an imide of the polyamic acid contained in any one of claims 1 to 3.

5. A polyimide film comprising the polyimide of claim 4.

6. The polyimide film according to claim 5, wherein the yellowness is below 20.

7. The polyimide film according to claim 5, wherein, The transmittance of light with a wavelength of 400nm is over 8%.

8. A laminate having a support and the polyimide film of claim 5.

9. The laminate according to claim 8, wherein, The support is a glass substrate. The internal stress between the polyimide film and the glass substrate is below 30 MPa.

10. An electronic device having the polyimide film of claim 5 and electronic components disposed on the polyimide film.

11. A method for manufacturing the polyamic acid composition according to any one of claims 1 to 3, It includes step S1, which involves reacting a diamine with a tetracarboxylic acid dianhydride in an organic solvent. The diamine comprises 4-aminobenzoic acid, specifically 4-aminophenyl ester. The content of 4-aminobenzoic acid 4-aminophenyl ester is more than 70 mol% relative to the total amount of the diamine. The 4-aminobenzoic acid 4-aminophenyl ester is supplied in step S1 in the form of a raw material monomer containing impurities. The impurities include aminophenol and methyl aminobenzoate. The Gardner color and Hassen color, measured in a cuvette with an optical path length of 1 cm using a 1% by mass solution of the aforementioned raw material monomer, were below 3.0 and below 200, respectively.

12. The method for manufacturing the polyamic acid composition according to claim 11, wherein, The content of aminophenol in the raw material monomer is less than 0.60% by mass relative to the total amount of 4-aminobenzoic acid 4-aminophenyl ester. The content of methyl aminobenzoate in the raw material monomer is less than 0.60% by mass relative to the total amount of 4-aminobenzoic acid 4-aminophenyl ester.

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