Polyamide acid composition, method for producing polyimide, method for producing laminate, and method for producing electronic device

Abstract

The polyamic acid composition includes a polyamic acid and an organic solvent. The organic solvent contains a compound represented by general formula (1) and a compound represented by general formula (2). In general formula (1), R1 represents a monovalent organic group having 2 or more carbon atoms. In general formula (2), R2 represents a monovalent organic group having 1 or more carbon atoms or a hydrogen atom. The content of the compound represented by general formula (2) is from 1 ppm by mass to 150 ppm by mass (inclusive) with respect to the total amount of the organic solvent.

Description

Technical Field

[0001] The present invention relates to a polyamic acid composition, a method for producing a polyimide, a method for producing a laminate, and a method for producing an electronic device. The present invention also relates to electronic device materials, thin-film transistor (TFT) substrates, flexible display substrates, color filters, printed materials, optical materials, image display devices (more specifically, liquid crystal display devices, organic EL, electronic paper, etc.), 3D displays, solar cells, touch panels, transparent conductive film substrates, and alternative materials for components currently using glass, all of which use polyimides. Background Art

[0002] With the rapid advancement of electronic devices such as liquid crystal displays, organic EL, and electronic paper displays, solar cells, and touch panels, devices are becoming increasingly thinner, lighter, and more flexible. In these devices, polyimide is being used as a substrate material instead of glass.

[0003] In these devices, various electronic components, such as thin-film transistors and transparent electrodes, are formed on substrates. The formation of these electronic components requires high-temperature processes. Polyimide has sufficient heat resistance to withstand high-temperature processes, and its coefficient of thermal expansion (CTE) is close to that of glass substrates and electronic components. Therefore, it is less likely to generate internal stress, making it a suitable substrate material for flexible displays and other applications.

[0004] The above-mentioned substrate material is produced by applying a solution (polyamic acid composition) in which polyamic acid is dissolved on a support, imidizing the polyamic acid to form a polyimide film, and laminating electronic components thereon.

[0005] As solvents for dissolving polyamic acid, amide-based solvents with relatively small carbon numbers, such as N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylacetamide (DMAC), are generally used. However, from the perspective of the impact on the environment and the human body, there is a demand for switching to safer solvents.

[0006] As the preparation example of the polyamic acid composition using a safe solvent, it is known that water is used as a solvent by utilizing polyamic acid salt (patent documentation 1 etc.). In addition, it is known that alkoxy-N-substituted propionamide is used as a low solvent for synthesizing polyamic acid with a low concern about teratogenicity (patent documentation 2 and patent documentation 3 etc.).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-36382

[0010] Patent Document 2: Japanese Patent Application No. 2017-517582

[0011] Patent Document 3: International Publication No. 2022 / 054850 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] The present inventors have verified that: if the polyamic acid composition described in patent documentation 1 to patent documentation 3 is applied to a support and polyamic acid is imidized, there is a tendency that poor adhesion is easily produced between the obtained polyimide film and the support, and the internal stress generated at the interface of the polyimide film and the support becomes larger. Hereinafter, the internal stress generated at the interface of the polyimide film and the support is sometimes referred to as "internal stress". If the internal stress becomes larger, it is likely to be difficult to be applied to electronic devices.

[0014] Furthermore, the present inventors have conducted verification and found that polyimides obtained from the polyamic acid compositions described in Patent Documents 1 to 3 have lower heat resistance than polyimides obtained using an amide solvent having a relatively small number of carbon atoms, such as NMP.

[0015] The present invention has been completed in view of the above-mentioned actual situation, and its purpose is to provide a polyamic acid composition, a method for producing a polyimide using the polyamic acid composition, a method for producing a laminate, and a method for producing an electronic device. The polyamic acid composition uses a highly safe solvent and can produce a polyimide that has excellent heat resistance and can reduce internal stress.

[0016] Solutions for solving problems

[0017] <Modes of the Invention>

[0018] The present invention includes the following aspects.

[0019] [1] A polyamic acid composition comprising polyamic acid and an organic solvent,

[0020] The organic solvent includes a compound represented by the following general formula (1) and a compound represented by the following general formula (2).

[0021] The content of the compound represented by the following general formula (2) is 1 mass ppm or more and 150 mass ppm or less relative to the total amount of the organic solvent.

[0022]

[0023] In the above general formula (1), R 1 represents a monovalent organic group having 2 or more carbon atoms,

[0024] In the above general formula (2), R 2 It represents a monovalent organic group having 1 or more carbon atoms or a hydrogen atom.

[0025] [2] The polyamic acid composition according to [1], wherein the compound represented by the general formula (1) is one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-n-octyl-2-pyrrolidone and 1-cyclohexyl-2-pyrrolidone.

[0026] [3] The polyamic acid composition according to [1] or [2], wherein the polyamic acid has a 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue as the tetracarboxylic dianhydride residue,

[0027] The content of the 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue is 50 mol% or more relative to all tetracarboxylic dianhydride residues constituting the polyamic acid.

[0028] [4] The polyamic acid composition according to any one of [1] to [3], wherein the polyamic acid has a p-phenylenediamine residue as a diamine residue,

[0029] The content of the p-phenylenediamine residue is 50 mol% or more relative to all diamine residues constituting the polyamic acid.

[0030] [5] A method for producing a polyimide, comprising heating the polyamic acid composition according to any one of [1] to [4] to imidize the polyamic acid.

[0031] [6] A method for producing a laminate comprising a support and a polyimide film,

[0032] In the production method, the polyamic acid composition according to any one of [1] to [4] is applied onto a support to form a coating film containing the polyamic acid, and the coating film is heated to imidize the polyamic acid.

[0033] [7] A method for manufacturing an electronic device, comprising:

[0034] Step Sa, heating the polyamic acid composition described in any one of [1] to [4] to imidize the polyamic acid;

[0035] In step Sb, electronic components are arranged on the polyimide film obtained in the above-mentioned step Sa.

[0036] Effects of the Invention

[0037] According to the present invention, there are provided a polyamic acid composition, which uses a highly safe solvent and can produce a polyimide having excellent heat resistance and reduced internal stress, a method for producing a polyimide, a method for producing a laminate, and a method for producing an electronic device using the polyamic acid composition. DETAILED DESCRIPTION

[0038] Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited thereto. In addition, all academic documents and patent documents described in this specification are cited as references in this specification.

[0039] First, the terms used in this specification are explained. "Constitutional unit" refers to a repeating unit that constitutes a polymer. "Polyamic acid" is a polymer containing a structural unit represented by the following general formula (3) (hereinafter sometimes referred to as "structural unit (3)").

[0040]

[0041] In the general formula (3), A 1 represents a tetracarboxylic dianhydride residue (a tetravalent organic group derived from tetracarboxylic dianhydride), A 2 represents a diamine residue (a divalent organic group derived from a diamine).

[0042] The content of the structural unit (3) relative to all the structural units constituting the polyamic acid is, for example, 50 mol% to 100 mol%, preferably 60 mol% to 100 mol%, more preferably 70 mol% to 100 mol%, further preferably 80 mol% to 100 mol%, further more preferably 90 mol% to 100 mol%, and can be 100 mol%.

[0043] The "1% weight loss temperature" is the temperature at which the weight of the polyimide at a measurement temperature of 150°C decreases by 1% relative to the weight of the polyimide (100% by weight). The 1% weight loss temperature is measured using the same method as in the examples described below or a method based thereon.

[0044] Hereinafter, "" may be appended after a compound name to collectively refer to a compound and its derivatives. Furthermore, when "" is appended after a compound name to indicate a polymer name, unless otherwise specified, this means that the repeating units of the polymer are derived from the compound or its derivatives. Furthermore, tetracarboxylic dianhydride may also be referred to as "acid dianhydride."

[0045] Unless otherwise specified, the components, functional groups, etc. exemplified in this specification may be used alone or in combination of two or more.

[0046] <Preferred Embodiments of the Invention>

[0047] The polyamic acid composition of the present embodiment comprises polyamic acid and an organic solvent. The organic solvent comprises a compound represented by the following general formula (1) and a compound represented by the following general formula (2). In the present embodiment, the content of the compound represented by the following general formula (2) is greater than or equal to 1 mass ppm and less than or equal to 150 mass ppm relative to the total amount of the organic solvent.

[0048]

[0049] In the general formula (1), R 1 represents a monovalent organic group having 2 or more carbon atoms. In the general formula (2), R 2 It represents a monovalent organic group having 1 or more carbon atoms or a hydrogen atom.

[0050] Hereinafter, the compound represented by the general formula (1) may be described as a "specific pyrrolidone-based compound". In addition, the compound represented by the general formula (2) may be described as a "specific primary amine". In addition, the content of the specific primary amine relative to the total amount of the organic solvent may be simply described as "the content of the specific primary amine". The method for measuring the content of the specific primary amine is the same method as in the examples described below or a method based on this method.

[0051] Generally, polyamic acid compositions use relatively small carbon amide solvents such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, and N,N-dimethylacetamide to improve solubility and properties. However, these solvents are considered harmful to health. In contrast, specific pyrrolidone compounds have minimal impact on the environment and the human body and are therefore highly safe.

[0052] On the other hand, N-substituted pyrrolidone-based solvents having a relatively large number of carbon atoms, such as specific pyrrolidone-based compounds, generally contain specific primary amines as impurities at a content of 500 ppm by mass or more.

[0053] Specific primary amine can hinder the molecular chain accumulation of the polyimide using the polyamic acid composition to manufacture, causes the increase of the internal stress produced at the interface of polyimide film and support, or because when polyimide film is formed, remains in film and thermal decomposition temperature is reduced.In contrast, in the polyamic acid composition of the present embodiment, the containing ratio of specific primary amine is made as below 150 mass ppm, therefore can obtain excellent heat resistance and the polyimide that can reduce internal stress.It should be noted that, if the containing ratio of specific primary amine is more than 1 mass ppm and the scope below 150 mass ppm, then the specific primary amine of minute amount exists the tendency of functioning as the accelerator of imidization reaction.

[0054] In order to obtain a polyimide with better heat resistance and further reduced internal stress, the content of the specific primary amine is preferably 120 mass ppm or less, more preferably 100 mass ppm or less, further preferably 80 mass ppm or less, further more preferably 50 mass ppm or less, and may also be 40 mass ppm or less, 30 mass ppm or less, 20 mass ppm or less, or 10 mass ppm or less. The content of the specific primary amine can be adjusted by changing the conditions of the organic solvent purification method. As the organic solvent purification method, for example, it can be appropriately selected from known methods such as precision distillation and methods using an adsorbent, without particular limitation.

[0055] In order to improve safety, R in the general formula (1) 1 , preferably a monovalent organic group having 3 or more carbon atoms, more preferably a monovalent organic group having 4 or more carbon atoms, and further preferably a monovalent organic group having 4 or more and 8 or less carbon atoms.

[0056] In addition, in order to obtain a polyimide with improved safety, better heat resistance, and further reduced internal stress, the specific pyrrolidone-based compound is preferably one or more selected from 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-n-octyl-2-pyrrolidone, and 1-cyclohexyl-2-pyrrolidone, and more preferably 1-butyl-2-pyrrolidone.

[0057] The structure of the specific primary amine tends to depend on the organic group bonded to the nitrogen atom of the specific pyrrolidone-based compound used. For example, the organic group bonded to the nitrogen atom (R 2 -CH2-) and the organic group (R 1 The same as the monovalent organic group shown).

[0058] The polyamic acid composition of the present embodiment may contain one pyrrolidone compound as the specific pyrrolidone compound, or may contain two or more pyrrolidone compounds. In addition, the polyamic acid composition of the present embodiment may contain one specific primary amine as the specific primary amine, or may contain two or more specific primary amines as the specific primary amine.

[0059] In order to obtain a polyimide with improved safety, better heat resistance, and further reduced internal stress, the polyamic acid composition of the present embodiment preferably contains only one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-n-octyl-2-pyrrolidone and 1-cyclohexyl-2-pyrrolidone as specific pyrrolidone-based compounds, and more preferably contains only 1-butyl-2-pyrrolidone. That is, in this embodiment, in order to obtain a polyimide that has improved safety and better heat resistance and can further reduce internal stress, the organic solvent preferably contains only one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-n-octyl-2-pyrrolidone and 1-cyclohexyl-2-pyrrolidone, and a specific primary amine, and more preferably contains only 1-butyl-2-pyrrolidone and a specific primary amine.

[0060] The polyamic acid (hereinafter, sometimes referred to as “polyamic acid (1)”) contained in the polyamic acid composition of the present embodiment has a tetracarboxylic dianhydride residue and a diamine residue.

[0061] In order to obtain a polyimide having better heat resistance and further reduced internal stress, the polyamic acid (1) preferably has a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue as the tetracarboxylic dianhydride residue. 3,3',4,4'-biphenyltetracarboxylic dianhydride may be referred to as "BPDA" hereinafter.

[0062] In order to obtain a polyimide having further excellent heat resistance and capable of further reducing internal stress, the content of the BPDA residue relative to the total tetracarboxylic dianhydride residues (100 mol%) constituting the polyamic acid (1) is preferably 50 mol% or more, more preferably 50 mol% or more and 100 mol% or less, further preferably 60 mol% or more and 99 mol% or less, and may be 80 mol% or more and 99 mol% or more, or 90 mol% or more and 99 mol% or less.

[0063] In order to obtain a polyimide having better heat resistance and further reduced internal stress, the polyamic acid (1) preferably has a p-phenylenediamine residue as a diamine residue. Hereinafter, p-phenylenediamine may be referred to as "PDA".

[0064] In order to obtain a polyimide having further excellent heat resistance and capable of further reducing internal stress, the content of the PDA residue relative to the total diamine residues (100 mol%) constituting the polyamic acid (1) is preferably 50 mol% or more, more preferably 50 mol% or more and 100 mol% or less, further preferably 60 mol% or more and 99.9 mol% or less, further preferably 70 mol% or more and 99.9 mol% or less, and may be 80 mol% or more and 99.9 mol% or less, or 90 mol% or more and 99.9 mol% or less.

[0065] In order to obtain a polyimide having better heat resistance and further reduced internal stress, the polyamic acid (1) preferably has a BPDA residue as a tetracarboxylic dianhydride residue and a PDA residue as a diamine residue. The polyamic acid (1) containing a BPDA residue and a PDA residue has a rigid structure and can therefore reduce internal stress.

[0066] On the other hand, when a polyimide film is formed from a polyamic acid composition comprising a polyamic acid (1) having a rigid structure and a specific primary amine, there is a tendency for internal stress to increase. In contrast, in the present embodiment, the content of the specific primary amine is set to 150 mass ppm or less, thereby obtaining a polyimide capable of reducing internal stress.

[0067] When synthesizing the polyamic acid (1), examples of acid dianhydrides (monomers) that can be used in addition to BPDA include spiro[11H-difuran[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetraone (hereinafter sometimes referred to as "SFDA"), 4,4'-oxydiphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, pyromellitic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3, 6,7-naphthalenetetracarboxylic dianhydride, p-phenylenebis(trimellitic anhydride), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 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 and derivatives thereof; these may be used alone or in combination of two or more.

[0068] In order to improve the transparency of the polyimide, it is preferred to use SFDA as the acid dianhydride (monomer). That is, the polyamic acid (1) preferably has an SFDA residue as the tetracarboxylic dianhydride residue. It should be noted that the SFDA residue is a tetravalent organic group represented by the following chemical formula (4).

[0069]

[0070] In the synthesis of polyamic acid (1), examples of diamines (monomers) that can be used in addition to PDA include 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'-diaminobenzanilide, m-phenylenediamine, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminobenzanilide. Aniline, 3,4'-oxydianiline, N,N'-bis(4-aminophenyl)terephthalamide, m-tolidine, o-tolidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexylamine), and derivatives thereof, which may be used alone or in combination of two or more.

[0071] In order to improve the adhesion between the obtained polyimide film and the substrate, it is preferable to use PAM-E as the diamine (monomer).

[0072] In order to obtain a polyimide having better heat resistance and further reduced internal stress, the polyamic acid composition of the present embodiment preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and even more preferably satisfies the following condition 3.

[0073] Condition 1: The polyamic acid (1) contains a BPDA residue and a PDA residue, and the organic solvent contains 1-butyl-2-pyrrolidone as the specific pyrrolidone-based compound.

[0074] Condition 2: The above-mentioned condition 1 is satisfied, and the content of the PDA residue is 70 mol% or more and 99.9 mol% or less relative to all diamine residues (100 mol%) constituting the polyamic acid (1).

[0075] Condition 3: The above-mentioned condition 2 is satisfied, and the content of the BPDA residue is 70 mol% or more and 99 mol% or less relative to all tetracarboxylic dianhydride residues (100 mol%) constituting the polyamic acid (1).

[0076] Polyamic acid (1) can be synthesized using a known general method, for example, it can be obtained by reacting diamine with tetracarboxylic dianhydride in an organic solvent. An example of a specific synthesis method of polyamic acid (1) is described. First, as a first method, the following method can be cited: in an inert gas atmosphere such as argon or nitrogen, diamine is dissolved in an organic solvent or dispersed in a slurry to prepare a diamine solution. Then, tetracarboxylic dianhydride is made to be dissolved in an organic solvent or dispersed in a slurry, or added to the above-mentioned diamine solution in a solid state. In addition, as a second method, the following method can be cited: in an inert gas atmosphere such as argon or nitrogen, tetracarboxylic dianhydride is made to be dissolved in an organic solvent or dispersed in a slurry to prepare a tetracarboxylic dianhydride solution. Then, diamine is made to be dissolved in an organic solvent or dispersed in a slurry, or added to the above-mentioned tetracarboxylic dianhydride solution in a solid state.

[0077] When polyamic acid (1) is synthesized using diamine and tetracarboxylic dianhydride, the desired polyamic acid (1) (polymer of diamine and tetracarboxylic dianhydride) can be obtained by adjusting the amount of diamine (the amount of each diamine when multiple diamines are used) and the amount of tetracarboxylic dianhydride (the amount of each tetracarboxylic dianhydride when multiple tetracarboxylic dianhydrides are used). The molar fraction of each residue in polyamic acid (1) is consistent with the molar fraction of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of polyamic acid (1). In addition, by blending two polyamic acids, polyamic acid (1) containing multiple tetracarboxylic dianhydride residues and multiple diamine residues can also be obtained. The temperature conditions for the reaction of diamine and tetracarboxylic dianhydride, that is, the synthesis reaction of polyamic acid (1) are not particularly limited, and are, for example, in the range of 20°C or more and 150°C or less. The reaction time for the synthesis reaction of polyamic acid (1) is, for example, in the range of 10 minutes or more and 30 hours or less.

[0078] The organic solvent used in the synthesis of polyamic acid (1) is preferably a solvent that can dissolve the tetracarboxylic dianhydride and diamine used, and more preferably a solvent that can dissolve the generated polyamic acid (1). As the organic solvent used in the synthesis of polyamic acid (1), from the perspective of safety, the above-mentioned specific pyrrolidone-based compound is preferably used. In addition, in the synthesis of polyamic acid (1), organic solvents other than the specific pyrrolidone-based compound may also be used. Examples of organic solvents other than specific pyrrolidone compounds include urea solvents such as tetramethylurea and N,N-dimethylethylurea; sulfoxide solvents such as dimethyl sulfoxide; sulfone solvents such as diphenylsulfone and tetramethylsulfone; amide solvents other than specific pyrrolidone compounds such as N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and hexamethylphosphoric acid triamide; ester solvents such as γ-butyrolactone; alkyl halide solvents such as chloroform and dichloromethane; aromatic hydrocarbon solvents such as benzene and toluene; phenolic solvents such as phenol and cresol; ketone solvents such as cyclopentanone; and ether solvents such as tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, dimethyl ether, diethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and p-cresol methyl ether. These solvents are generally used alone, but two or more may be used in combination as needed. Furthermore, the synthesis reaction of the polyamic acid (1) is preferably performed under an inert gas atmosphere such as argon or nitrogen.

[0079] The polyamic acid composition of the present embodiment comprises polyamic acid (1) and an organic solvent. When the above method is used to obtain polyamic acid (1), the reaction solution (reacted solution) itself can also be used as the polyamic acid composition of the present embodiment. When the reaction solution itself is used as the polyamic acid composition of the present embodiment, the organic solvent used in the synthesis of polyamic acid (1) is preferably the above-mentioned specific pyrrolidone-based compound. In addition, the solid polyamic acid (1) obtained by removing the solvent from the reaction solution can be dissolved in the specific pyrrolidone-based compound to prepare the polyamic acid composition of the present embodiment.

[0080] The polyamic acid composition of the present embodiment may also include an organic solvent other than the specific pyrrolidone compound. However, from the perspective of safety, the containing rate of the specific pyrrolidone compound in the polyamic acid composition of the present embodiment is preferably more than 70 weight % relative to the total amount of the organic solvent in the polyamic acid composition, more preferably more than 80 weight %, and then preferably more than 90 weight %, and particularly preferably the remainder other than the specific primary amine in the organic solvent is all specific pyrrolidone compound. It should be noted that the containing rate of the polyamic acid (1) in the polyamic acid composition of the present embodiment is not particularly limited, for example, is more than 1 weight % and less than 80 weight % relative to the polyamic acid composition total amount.

[0081] The weight average molecular weight of the polyamic acid (1) also depends on its use, and is 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 further 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, sufficient solubility to a solvent is exhibited, and thus a coated film or a polyimide film having a smooth surface and uniform thickness can be obtained using the polyamic acid composition. The weight average molecular weight used herein refers to a polyethylene oxide-converted value measured using gel permeation chromatography (GPC).

[0082] In addition, as a method of controlling the molecular weight of the polyamic acid (1), a method of making either of the acid dianhydride and the diamine in excess, and a method of quenching the reaction by reacting with a monofunctional anhydride such as phthalic anhydride, aniline, and the like can be given. When either of the acid dianhydride and the diamine is made in excess for polymerization, if the molar ratio of the raw materials thereof is between 0.95 and 1.05, a polyimide film having sufficient strength can be obtained. Note that the above molar ratio of the raw materials is the ratio of the total amount of substance of the diamines used in the synthesis of the polyamic acid (1) to the total amount of substance of the acid dianhydrides used in the synthesis of the polyamic acid (1) (total amount of substance of diamines / total amount of substance of acid dianhydrides). In addition, by end-capping with phthalic anhydride, maleic anhydride, aniline, and the like, coloring of the polyimide obtained using the polyamic acid (1) can be further reduced.

[0083] In addition, in order to shorten the heating time and exhibit the properties, the polyamic acid composition of the present embodiment can also contain an imidization accelerator and / or a dehydration catalyst.

[0084] As the above imidization accelerator, there is no particular limitation, and a tertiary amine can be used. As the tertiary amine, a heterocyclic tertiary amine is preferred. As preferred specific examples of the heterocyclic tertiary amine, pyridine, methylpyridine, quinoline, isoquinoline, imidazole, and the like can be given. As the above dehydration catalyst, as preferred specific examples, acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, and the like can be given.

[0085] From the viewpoint of shortening the heating time and developing the properties, the amount of the imidization accelerator is preferably from 0.1 parts by weight to 20 parts by weight, more preferably from 0.5 parts by weight to 20 parts by weight, relative to 100 parts by weight of the polyamic acid (1). Furthermore, from the viewpoint of shortening the heating time and developing the properties, the amount of the dehydration catalyst is preferably from 0.1 parts by weight to 10 parts by weight, more preferably from 0.5 parts by weight to 5 parts by weight, relative to 100 parts by weight of the polyamic acid (1).

[0086] As an imidization accelerator, imidazoles are preferred. It should be noted that in this specification, imidazoles refer to compounds with 1,3-oxadiazole rings (1,3-oxadiazole ring structures). As the imidazoles that can be added in the polyamic acid composition of the present embodiment, there is no particular limitation, for example, 1H-imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, etc. Among them, preferably 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, more preferably 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole.

[0087] Relative to 1 mole of the amide group of polyamic acid (1), the content of imidazoles is preferably more than 0.005 mole and less than 0.1 mole, more preferably more than 0.01 mole and less than 0.08 mole, further preferably more than 0.015 mole and less than 0.050 mole. By containing more than 0.005 mole of imidazoles, the film strength and the transparency of polyimide can be improved, by setting the content of imidazoles to less than 0.1 mole, the storage stability of polyamic acid (1) can be maintained, and heat resistance is improved. It should be noted that, in this specification, "amide group of polyamic acid (1)" refers to the amide group generated by the polymerization reaction of diamine and tetracarboxylic dianhydride.

[0088] There is no particular restriction on the mixing method of polyamic acid (1) and imidazoles. From the viewpoint of the ease of controlling the molecular weight of polyamic acid (1), it is preferred to add imidazoles to the polyamic acid (1) after polymerization. At this time, imidazoles can be directly added to polyamic acid (1), or imidazoles can be dissolved in a solvent in advance and the solution can be added to polyamic acid (1). The adding method is not particularly limited. The polyamic acid composition of the present embodiment can also be prepared by adding imidazoles to a solution (reacted solution) containing polyamic acid (1) after polymerization.

[0089] In the polyamic acid composition of the present embodiment, also various organic or inorganic low molecular compounds or macromolecular compounds can be mixed as additives.As additives, for example, plasticizers, antioxidants, dyes, surfactants, leveling agents, organosilicon, microparticles, sensitizers etc. can be used.Comprise the organic microparticles formed by polystyrene, polytetrafluoroethylene etc., the inorganic microparticles formed by colloidal silicon dioxide, carbon, layered silicates etc. in the microparticles, and they can be porous structures, hollow structures.In addition, the function and form of microparticles are not particularly limited, for example, can be pigments, can also be fillers, can also be fibrous particles.

[0090] In addition, in order to show the suitable adhesion with support, the polyamic acid composition of the present embodiment can contain silane coupling agent.Silane coupling agent can use known silane coupling agent without particular restriction.In order to show the good adhesion with support, as spendable silane coupling agent, preferably contain amino compound, more preferably selected from the group consisting of 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl diethoxymethyl silane, 3-(ethoxydimethylsilyl) propylamine, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl methyl dimethoxysilane and N-phenyl-3-aminopropyl trimethoxysilane, further preferably selected from the group consisting of 3-aminopropyl triethoxysilane and 3-aminopropyl diethoxymethyl silane, particularly preferably 3-aminopropyl triethoxysilane.

[0091] The blending ratio of the silane coupling agent to 100 parts by weight of the polyamic acid (1) 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 blending ratio of the silane coupling agent to 0.01 parts by weight or more, the effect of suppressing peeling from the support can be fully exerted, and by setting the blending ratio of the silane coupling agent to 0.50 parts by weight or less, the decrease in the molecular weight of the polyamic acid (1) can be suppressed, thereby suppressing embrittlement of the polyimide film.

[0092] The production method of the polyimide of the present embodiment includes a step of imidizing the polyamide acid composition of the present embodiment by heating. As the method of imidizing the polyamide acid (1), there is no particular limitation, and a known method can be employed. Hereinafter, an example of the method of imidizing the polyamide acid (1) will be described. The imidization is performed by dehydration and ring closure of the polyamide acid (1). This dehydration and ring closure can be performed by an azeotropic method using an azeotropic solvent, a thermal method, or a chemical method. Alternatively, the polyamide acid composition can be directly put into a container in which a release treatment such as coating with a fluorine-based resin has been performed, and the polyamide acid composition can be heated and dried under reduced pressure, whereby the dehydration and ring closure of the polyamide acid (1) can be performed. By the dehydration and ring closure of the polyamide acid (1) using these methods, a polyimide can be obtained. Note that the heating time of each of the above treatments varies depending on the amount of the polyamide acid composition subjected to the dehydration and ring closure and the heating temperature, and is preferably set to a range of 1 minute or more and 300 minutes or less after the temperature of the treatment reaches the maximum temperature.

[0093] In addition, the imidization of the polyamide acid (1) to a polyimide can be performed at an arbitrary ratio of 1% or more and 100% or less. That is, a part of the polyamide acid (1) can be synthesized to be imidized. In particular, in the case where the imidization is performed by heating, the ring closure reaction of the polyamide acid (1) to a polyimide is simultaneously performed with the hydrolysis of the polyamide acid (1), and the molecular weight of the polyimide produced can be lower than the molecular weight of the polyamide acid (1), and thus, from the viewpoint of improving the mechanical properties, it is preferable to imidize a part of the polyamide acid (1) in the polyamide acid composition in advance before forming a polyimide film described later. In this specification, the polyamide acid that is partially imidized is sometimes referred to as a "polyamide acid".

[0094] The production method of the laminate of the present embodiment is a production method of a laminate having a support and a polyimide film (in detail, a polyimide film containing an imidization product of the polyamide acid (1)). In the production method of the laminate of the present embodiment, the polyamide acid (1) is imidized by dehydration and ring closure of the polyamide acid (1) by heating. The method of heating the polyamide acid (1) is not particularly limited, and for example, a method in which a coating film containing the polyamide acid (1) is formed by coating the above-described polyamide acid composition of the present embodiment on a support, and the obtained coating film is subjected to heat treatment at a temperature of, for example, 40°C or higher and 500°C or lower can be exemplified. As the support, a glass substrate, a metal plate, a PET film (polyethylene terephthalate film), a glass substrate with a sacrificial layer on which an amorphous silicon layer (a-Si layer) is laminated, and the like can be given. According to this method, a laminate having a support and a polyimide film (in detail, a polyimide film containing an imidization product of the polyamide acid (1)) disposed on the support can be obtained.

[0095] The content of the polyimide in the polyimide film formed by the above method is, for example, 70 wt % or more, preferably 80 wt % or more, more preferably 90 wt % or more, and may be 100 wt % relative to the total amount of the polyimide film. As components other than the polyimide in the polyimide film, for example, the above-mentioned additives (more specifically, microparticles, etc.) may be mentioned.

[0096] The method for producing an electronic device (more specifically, a flexible device, etc.) of the present embodiment comprises: a step Sa of heating the polyamic acid composition of the present embodiment to imidize the polyamic acid (1); and a step Sb of arranging an electronic component on the polyimide film obtained in the step Sa. The step Sa is, for example, the same as the method for producing a laminate of the present embodiment described above. In the step Sb, for example, an electronic component (such as a TFT) is directly or indirectly arranged on the polyimide film obtained in the step Sa.

[0097] When manufacturing electronic devices for flexible displays, a polyimide film is first formed on an inorganic substrate such as glass as a support. Electronic components such as TFTs are then arranged (formed) on the polyimide film, forming the electronic device on the support. The TFT formation process is typically performed over a wide temperature range of 150°C to 650°C. However, in practice, to achieve desired performance, oxide semiconductor layers and a-Si layers are sometimes formed at temperatures above 300°C, and the a-Si layer is then crystallized using a laser or other method.

[0098] At this time, if the thermal decomposition temperature of the polyimide film is low, there is a possibility that outgassing will be generated during the formation of electronic components and adhere to the oven in the form of sublimates, causing contamination in the oven, or that the inorganic film (barrier film, etc., described later) or the electronic component formed on the polyimide film will peel off. Therefore, the 1% weight loss temperature of the polyimide is preferably above 500°C, more preferably above 550°C, and even more preferably above 560°C. The upper limit of the 1% weight loss temperature of the polyimide is preferably as high as possible, for example, 600°C. The 1% weight loss temperature can be adjusted, for example, by changing the content of residues having a rigid structure (more specifically, BPDA residues, PDA residues, etc.). More specifically, before TFT formation, an inorganic film such as a silicon oxide film (SiOx film) or a silicon nitride film (SiNx film) is formed on the polyimide film as a barrier film. If the polyimide has low heat resistance, imidization is not fully progressed, or there is a large amount of residual solvent, the polyimide and the inorganic film may be separated during the high-temperature process after the inorganic film is laminated due to volatile components such as decomposition gas of the polyimide. Therefore, it is desirable that the weight loss rate of the polyimide when isothermally maintained at a temperature within the range of 400°C to 450°C is less than 1%, while the 1% weight loss temperature of the polyimide is 500°C or higher.

[0099] In addition, when the glass transition temperature (Tg) of the polyimide is significantly lower than the process temperature, positional offset may occur during the formation of the electronic component. Therefore, the Tg of the polyimide is preferably 300°C or higher, more preferably 350°C or higher, further preferably 400°C or higher, and further preferably 420°C or higher. The higher the upper limit of the Tg of the polyimide, the better, for example, 470°C. In addition, in general, the thermal expansion coefficient of the glass substrate is smaller than that of the resin, so internal stress is generated between the glass substrate and the polyimide film. If the internal stress of the laminate of the glass substrate, the electronic component and the polyimide film used as the support is high, the laminate containing the polyimide film will shrink when it is cooled to room temperature after expanding in the high-temperature TFT formation process, resulting in problems such as warping and breakage of the glass substrate and peeling of the polyimide film from the glass substrate. Therefore, in a laminate comprising a support and a polyimide film, the internal stress between the polyimide film and the support is preferably 30 MPa or less, more preferably 20 MPa or less, even more preferably 10 MPa or less, and even more preferably 9 MPa or less. The lower limit of the internal stress is preferably as low as possible and may be 0 MPa. The internal stress can be measured using the same method as described in the Examples below or a method based on that method.

[0100] The polyimide obtained by the manufacture method of the present embodiment can be suitably used as a material for display substrates such as TFT substrates and touch panel substrates. When polyimide is used for the above-mentioned purposes, most of them adopt the method of peeling the polyimide film from the support after forming an electronic device (specifically, an electronic device having an electronic component formed on a polyimide film) on the support as described above. In addition, as the material of the support, alkali-free glass is preferably used. Below, an example of the manufacture method of the laminate of a polyimide film and a support is described in detail.

[0101] First, the polyamic acid composition of the present embodiment is coated (cast) on a support to form a laminate containing a coating film composed of a coating film containing polyamic acid (1) and a support. Then, the laminate containing the coating film is heated under conditions such as a temperature of 40°C or more and 200°C or less. The heating time at this time is, for example, 3 minutes or more and 120 minutes or less. In addition, a multi-stage heating process may be provided, such as heating the laminate containing the coating film at a temperature of 50°C for 30 minutes and then heating it at a temperature of 100°C for 30 minutes. Then, in order to promote the imidization of the polyamic acid (1) in the coating film, the laminate containing the coating film is heated under conditions such as a maximum temperature of 200°C or more and 500°C or less. The heating time at this time (heating time at the maximum temperature) is, for example, 1 minute or more and 300 minutes or less. At this time, it is preferred to gradually heat 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. In addition, the maximum temperature is preferably in the range of 250°C or more and 480°C or less. If the maximum temperature is 250°C or more, imidization proceeds fully, and if the maximum temperature is 480°C or less, thermal degradation and coloration of the polyimide can be suppressed. In addition, it is also possible to maintain an arbitrary temperature for an arbitrary 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 in order to exhibit higher transparency, it is preferably carried out under reduced pressure or in an inert gas such as nitrogen. In addition, as a heating device, a well-known device such as a hot air oven, an infrared oven, a vacuum oven, an inert oven, a hot plate, etc. can be used. After these steps, the polyamic acid (1) in the coating film is imidized, and a laminate of a support and a polyimide film (a film containing an imide compound of polyamic acid (1)) can be obtained.

[0102] The method for peeling off the polyimide film from the laminated body of the support body and the polyimide film obtained can use a known method.For example, it can be peeled off by hand, or it can be peeled off using mechanical devices such as drive rollers and robots. Furthermore, it is also possible to adopt a method in which a peeling layer is provided between the support body and the polyimide film, or a silicon oxide film is formed on a substrate having a plurality of grooves, and the silicon oxide film is used as a base layer to form the polyimide film, so that the etching solution of silicon oxide is infiltrated between the substrate and the silicon oxide film, thereby the method for peeling off the polyimide film. In addition, it is also possible to adopt a method in which the polyimide film is separated by irradiation of a laser.

[0103] The transparency of a polyimide film can be evaluated using the total light transmittance (TT) according to JIS K7361-1:1997 and the haze according to JIS K7136-2000. When a polyimide film is used in applications requiring high transparency, the total light transmittance of the polyimide film is preferably 75% or more, more preferably 80% or more. In addition, when a polyimide film is used 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 may also be 0%. In applications requiring high transparency, the polyimide film is required to have high transmittance over the entire wavelength range, but the polyimide film has a tendency to easily absorb light on the short wavelength side, and the film itself is often colored yellow. In order to use the polyimide film in applications requiring high transparency, it is preferred to reduce the coloring of the polyimide film. Specifically, in order to use the polyimide film in applications requiring high transparency, the yellowness index (YI) of the polyimide film is preferably 25 or less, more preferably 20 or less, and may be 0. YI can be measured in accordance with JIS K7373-2006. Thus, the polyimide film with reduced coloration and enhanced transparency is suitable for transparent substrates for glass replacement applications, etc., and substrates with sensors or camera modules provided on the back surface.

[0104] In addition, on supports such as glass substrates, be coated with polyamic acid composition, heat and imidize, after forming electronic component etc., polyimide film is peeled off in such intermittent device manufacturing process, preferably the adhesion between support and polyimide film is excellent.Herein said adhesion refers to sealing strength.After forming electronic component etc. on the polyimide film on support, from support, peel off in the manufacturing process of the polyimide film formed with electronic component etc., if polyimide film and the adhesion of support are excellent, then electronic component etc. can be formed or installed more accurately.On support, across in the manufacturing process of polyimide film configuration electronic component etc., consider from the viewpoint of improving productivity, the peel strength between support and polyimide film is preferably more than 0.05N / cm, more preferably more than 0.1N / cm.

[0105] In the manufacturing process as described above, when the polyimide film is peeled off from the laminate of the support and the polyimide film, the polyimide film is mostly peeled off from the support by laser irradiation. In this case, it is necessary to make the polyimide film absorb the laser, so the cut-off wavelength of the polyimide film is required to be a wavelength longer than the wavelength of the laser used for peeling. Laser peeling mostly uses a XeCl excimer laser with a wavelength of 308nm, so the cut-off wavelength of the polyimide film is preferably above 312nm, more preferably above 330nm. On the other hand, if the cut-off wavelength is a long wavelength, there is a tendency for the polyimide film to be colored yellow, so the cut-off wavelength of the polyimide film is preferably below 390nm. From the viewpoint of both transparency (low yellowness) and the processability of laser peeling, the cut-off wavelength of the polyimide film is preferably above 320nm and below 390nm, more preferably above 330nm and below 380nm. It should be noted that the cut-off wavelength in this specification refers to the wavelength with a transmittance of 0.1% or less as measured by an ultraviolet-visible spectrophotometer.

[0106] The polyamic acid composition of this embodiment and the polyimide obtained by the production method of this embodiment can be used directly in a coating or molding process for manufacturing products or components, or can be used as a material for further coating or other treatment of a film-shaped formed article. In order to use in a coating or molding process, the polyamic acid composition or polyimide can be dissolved or dispersed in an organic solvent as needed, and then a photocurable component, a thermosetting component, a non-polymerizable binder resin, and other components can be added as needed to prepare a composition containing polyamic acid (1) or polyimide.

[0107] Various inorganic thin films such as metal oxide thin films and transparent electrodes can also be formed on the surface of the polyimide film obtained by the manufacturing method of this embodiment. There are no particular limitations on the film-forming methods of these inorganic thin films, and examples thereof include PVD methods such as sputtering, vacuum evaporation, and ion plating, and CVD methods.

[0108] The polyimide film obtained by the manufacture method of the present embodiment has, in addition to heat resistance, a small internal stress generated when forming a laminate with a glass substrate, and can ensure adhesion to inorganic materials in high temperature processes, and is therefore preferably used in fields and products where these characteristics are considered to be effective. For example, the polyimide film obtained by the manufacture method of the present embodiment is preferably used in image display devices such as liquid crystal display devices, organic EL, electronic paper, printed matter, color filters, flexible displays, optical films, 3D displays, touch panels, transparent conductive film substrates, solar cells, and more preferably as an alternative material for the part currently using glass. In these uses, the thickness of the polyimide film is, for example, more than 1 μm and less than 200 μm, preferably more than 5 μm and less than 100 μm. The thickness of the polyimide film can be measured using a laser hologram.

[0109] In addition, the polyamic acid composition of the present embodiment can be suitably used for the manufacture method of following polyimide film: on a support, apply the polyamic acid composition, heat and imidize, and peel off the polyimide film from the support. In addition, the polyamic acid composition of the present embodiment can be suitably used for the device manufacturing process of following intermittent type: on a support, apply the polyamic acid composition, heat and imidize, and after forming electronic component etc. on the formed polyimide film, peel off the polyimide film that is formed with electronic component etc. from the support. Therefore, the manufacture method of the electronic device involved in the present embodiment can also include peeling off the operation of the polyimide film that is formed with electronic component etc. from the support.

[0110] Example

[0111] Hereinafter, examples of the present invention will be described, but the scope of the present invention is not limited to the following examples.

[0112] <Measurement Methods of Physical Properties>

[0113] First, a method for measuring the physical properties of polyimide (polyimide film) will be described.

[0114] [Internal stress]

[0115] On a glass substrate (trade name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) manufactured by Corning Inc., the amount of warpage was measured in advance, each polyamic acid composition prepared in the embodiments and comparative examples described later was applied using a spin coater, and after heating at 120 ° C for 30 minutes in air, the laminate having a polyimide film having a thickness of 10 μm was obtained at 460 ° C under a nitrogen atmosphere. In order to eliminate the influence of water absorption of the polyimide film, the laminate was dried at 120 ° C for 10 minutes, and then the warpage of the laminate under a nitrogen atmosphere at a temperature of 25 ° C was measured using a thin film stress measuring device (" FLX-2320-S" manufactured by KLA-Tencor). Then, according to the warpage of the glass substrate before the polyimide film is formed and the warpage of the laminate, the internal stress generated between the glass substrate and the polyimide film was calculated using the Stoney formula. When the internal stress was 9 MPa or less, it was evaluated as “the internal stress could be reduced.” On the other hand, when the internal stress exceeded 9 MPa, it was evaluated as “the internal stress could not be reduced.”

[0116] [1% weight loss temperature (TD1)]

[0117] Polyimide films sampled from each of the laminates obtained in the Examples and Comparative Examples described below (specifically, polyimide films sampled to a weight of 10 mg) were used as test samples. Using a differential thermal and thermogravimetric analyzer ("TG / DTA7200" manufactured by Hitachi High-Tech Science Co., Ltd.), the temperature was raised from 25°C to 650°C at 20°C / minute in a nitrogen atmosphere. The 1% weight loss temperature (TD1) was defined as the temperature at which the sample weight at a measurement temperature of 150°C decreased by 1% by weight relative to this reference. A TD1 of 560°C or higher was evaluated as "excellent heat resistance." On the other hand, a TD1 of less than 560°C was evaluated as "poor heat resistance."

[0118] [Butylamine content]

[0119] For the organic solvents S1 to S6 used in the Examples and Comparative Examples described below, gas chromatography-mass spectrometry (GC / MS analysis) was performed using a gas chromatograph-mass spectrometer ("GC-2025" manufactured by Shimadzu Corporation) under the following conditions. The content of butylamine (specific primary amine) relative to the total amount of the organic solvent was calculated from the peak area values ​​in the resulting GC / MS chart. It should be noted that no primary amines other than butylamine were detected in any of the organic solvents.

[0120] (GC / MS analysis conditions)

[0121] Column temperature: 40℃~280℃

[0122] Carrier gas: Helium (2.19 mL / min)

[0123] <Production of Polyimide Film>

[0124] Hereinafter, the preparation method of the polyimide film (laminate) of embodiment and comparative example is described.It should be noted that, below, compound and reagent are described with following abbreviation.In addition, the preparation of the polyamic acid composition used in the production of polyimide film is all carried out under nitrogen atmosphere.

[0125] NBP: 1-Butyl-2-pyrrolidone

[0126] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0127] SFDA: Spiro[11H-difuro[3,4-b:3',4'-i]xanthene-11,9'-[9H]fluorene]-1,3,7,9-tetraone

[0128] PDA: p-phenylenediamine

[0129] PAM-E: 1,3-bis(3-aminopropyl)tetramethyldisiloxane

[0130] [Preparation of organic solvent]

[0131] First, NBP manufactured by Tokyo Chemical Industry Co., Ltd. (butylamine content: 1740 mass ppm, hereinafter referred to as "organic solvent S6") was prepared. Next, organic solvent S6 was distilled using a distillation apparatus whose interior was purged with nitrogen, and the fractions were fractionated to obtain five organic solvents S1 to S5 having different butylamine contents. The butylamine contents of organic solvents S1 to S5 are as follows.

[0132] Butylamine content in organic solvent S1: 10 ppm by mass

[0133] Butylamine content in organic solvent S2: 100 mass ppm

[0134] Butylamine content in organic solvent S3: 500 ppm by mass

[0135] Butylamine content in organic solvent S4: 1000 mass ppm

[0136] Butylamine content in organic solvent S5: 1500 ppm by mass

[0137] [Example 1]

[0138] 56.6 g of organic solvent S1 was added to a 300 mL glass separable flask equipped with a stirrer equipped with a stainless steel stirring rod and a nitrogen inlet tube as an organic solvent for polymerization. Next, while stirring the contents of the flask, 0.152 g of SFDA was placed in the flask and dissolved. Next, 2.669 g of PDA, 0.031 g of PAM-E, and 7.148 g of BPDA were added to the flask contents, and the flask contents were stirred for 5 hours at a temperature of 90° C. to obtain a polyamic acid composition. The obtained polyamic acid composition was applied to a glass substrate manufactured by Corning Incorporated (trade name: Eagle XG, material: alkali-free glass, thickness: 0.7 mm, size: 100 mm × 100 mm) using a spin coater, and then heated at 80°C in air for 30 minutes, and then heated at 460°C for 20 minutes in a nitrogen atmosphere to obtain a laminate having a polyimide film with a thickness of 10 μm on the glass substrate (the laminate of Example 1).

[0139] [Example 2 and Comparative Examples 1 to 4]

[0140] Except that the organic solvent for polymerization was changed to the solvent shown in Table 1, the same method as in Example 1 was used to obtain laminated bodies of Example 2 and Comparative Examples 1 to 4, respectively.

[0141] With respect to Example 1, Example 2 and Comparative Examples 1 to 4, the organic solvent used, the content of butylamine in the organic solvent used, the acid dianhydride and diamine used, as well as the internal stress and TD1 are shown in Table 1. It should be noted that, in Table 1, “-” means that the polyimide film formed is brittle and therefore cannot be measured. In addition, in Table 1, the numerical value of the “acid dianhydride” column is the content rate (unit: mole %) of each acid dianhydride relative to the total amount (100 mol %) of the diamine used. In addition, in Table 1, the numerical value of the “diamine” column is the content rate (unit: mole %) of each diamine relative to the total amount (100 mol %) of the diamine used. In addition, with respect to any one of Example 1, Example 2 and Comparative Examples 1 to 4, the mole fraction of each residue of polyamic acid in the prepared polyamic acid composition is consistent with the mole fraction of each monomer (diamine and tetracarboxylic dianhydride) used in the synthesis of polyamic acid.

[0142] [Table 1]

[0143]

[0144] As shown in Table 1, the content of the specific primary amine (butylamine) in the organic solvent used in Examples 1 and 2 was 1 ppm by mass or more and 150 ppm by mass or less relative to the total amount of the organic solvent. In Examples 1 and 2, the internal stress was 9 MPa or less. Therefore, the laminates obtained in Examples 1 and 2 had reduced internal stress. In Examples 1 and 2, TD1 was 560°C or higher. Therefore, the polyimide films obtained in Examples 1 and 2 had excellent heat resistance.

[0145] As shown in Table 1, the content of the specific primary amine (butylamine) in the organic solvent used in Comparative Examples 1 to 4 exceeded 150 mass ppm relative to the total amount of the organic solvent. In Comparative Examples 1 to 3, the internal stress exceeded 9 MPa. Therefore, the laminates obtained in Comparative Examples 1 to 3 could not reduce the internal stress. In Comparative Examples 1 to 3, TD1 was lower than 560°C. Therefore, the heat resistance of the polyimide films obtained in Comparative Examples 1 to 3 was not excellent. In Comparative Example 4, the polyimide film formed was brittle, so the internal stress and TD1 could not be measured.

[0146] The above results indicate that the present invention can provide a polyamic acid composition capable of producing a polyimide having excellent heat resistance and reduced internal stress using a highly safe solvent.

Claims

1. A polyamic acid composition comprising polyamic acid and an organic solvent, The organic solvent comprises: a compound represented by the following general formula (1) and a compound represented by the following general formula (2), The content of the compound represented by the following general formula (2) is 1 mass ppm or more and 150 mass ppm or less relative to the total amount of the organic solvent, In the general formula (1), R 1 represents a monovalent organic group having 2 or more carbon atoms, In the general formula (2), R 2 It represents a monovalent organic group having 1 or more carbon atoms or a hydrogen atom.

2. The polyamic acid composition according to claim 1, wherein The compound represented by the general formula (1) is one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-n-octyl-2-pyrrolidone and 1-cyclohexyl-2-pyrrolidone.

3. The polyamic acid composition according to claim 1, wherein The polyamic acid has a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue as a tetracarboxylic dianhydride residue, The content of the 3,3′,4,4′-biphenyltetracarboxylic dianhydride residue is 50 mol% or more relative to all tetracarboxylic dianhydride residues constituting the polyamic acid.

4. The polyamic acid composition according to claim 1, wherein The polyamic acid has a p-phenylenediamine residue as a diamine residue, The content of the p-phenylenediamine residue is 50 mol% or more based on all diamine residues constituting the polyamic acid.

5. A method for producing a polyimide, wherein: The polyamic acid composition according to claim 1 is heated to imidize the polyamic acid.

6. A method for producing a laminate comprising a support and a polyimide film. In the production method, the polyamic acid composition according to claim 1 is applied onto a support to form a coating film containing the polyamic acid, and the coating film is heated to imidize the polyamic acid.

7. A method for manufacturing an electronic device, comprising: Step Sa, heating the polyamic acid composition according to claim 1 to imidize the polyamic acid; and In step Sb, electronic components are arranged on the polyimide film obtained in step Sa.

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