Solvent for resin synthesis and method for producing synthetic resin using the same

Abstract

[Problem] The present invention provides a solvent for use in the synthesis of synthetic resins such as polyimide resins, polyurethane resins, etc., which enables the synthesis of polymers with high molecular weight in a short time, and which has high transparency and storage stability, with the reaction solution being neither turbid during the reaction nor after the reaction.[Solution] A solvent (C) for resin synthesis, containing 10 to 99.9999 mass% of an amide-based solvent (A), and 0.0001 to 5 mass% of a reaction accelerator (B) which is an aliphatic or aromatic tertiary amine compound having one or more tertiary amino groups in the molecule.

Description

Technical Field

[0001] This invention relates to a solvent for synthesizing synthetic resins such as polyimide resin, polyamide-imide resin, and polyurethane resin, and a method for manufacturing synthetic resins using the solvent. Background Technology

[0002] Polyimides (including polyimides, polyamide-imides, polyester-imides, and polyether-imides) not only possess a robust molecular structure and excellent heat resistance, but also exhibit mechanical and chemical properties not found in other resins. As high-performance plastics, they are widely used in films, coatings, protective films, electrical insulation materials, bearings, heat-resistant coatings, heat-insulating shafts, heat-insulating trays, electronic components, automotive parts, and various other fields. Aromatic polyimides, in particular, synthesized from aromatic diamines and aromatic tetracarboxylic dianhydrides, possess a robust molecular structure and strong intermolecular forces, making them widely recognized as super engineering plastics with the highest levels of thermal, mechanical, and chemical properties among synthetic resins. Polyimides are typically infusible and insoluble, and are therefore synthesized by reacting diamines or diisocyanates with acid dianhydrides in an organic solvent at a low temperature (around room temperature) to synthesize polyamic acid as a precursor. The resulting precursor solution is then processed into a membrane or similar material, followed by dehydration and cyclization (imidization) via heating or a chemical reaction. Alternatively, when synthesizing polyimides or thermoplastic polyimides soluble in organic solvents, imidization can be performed by heating in the same solvent after synthesizing the polyimide precursor. For various polyimides, to obtain high-performance products, it is necessary to stably synthesize high-molecular-weight precursor solutions (varnishes), and the resulting precursor solutions need to possess excellent storage stability (solution stability). Research related to the synthesis of these precursors has also attracted attention.

[0003] The appropriate solvent (good solvent) varies depending on the chemical structure of the polyimide, but the synthesis of polyimide precursors often uses organic polar solvents such as amide solvents. Amide solvents are known to have the following characteristics: excellent solubility, high boiling or ignition point, and thermal and chemical stability. However, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAC), commonly used in the synthesis of polyimide precursors, can easily cause inflammation upon contact with skin or eyes, and may have carcinogenic or teratogenic effects, posing a problem for human health. NMP, in particular, also presents environmental, toxicological, and / or administrative issues (REACH; Registration, Evaluation, Authorization and Restriction of Chemicals Act) (Patent Document 1 and Patent Document 2).

[0004] To address the issues of low safety associated with amide solvents such as NMP and DMF, N-butyl-2-pyrrolidone (NBP) and 3-methoxy-N,N-dimethylpropionamide (KJCMPA (registered trademark)), both amide solvents with high safety and solubility, have recently attracted attention as solvents for the synthesis of polyimides, including polyimide precursors (Patent Documents 3 and 4). However, these prior art technologies only aim to use NBP or KJCMPA as solvents to replace NMP, thus only requiring the same level of solubility as existing NMP, without solving the various problems associated with existing NMP, such as: difficulty in increasing the molecular weight of polyimide precursors, low solution stability of polyimide precursors (easily causing turbidity), easy whitening during polyimide film formation, and easy generation of surface inhomogeneity (mura). On the other hand, to address the whitening or surface unevenness issues during polyimide film formation, there are reports of using KJCMPA or 3-butoxy-N,N-dimethylpropionic acid (KJCBPA (registered trademark)) (Patent Documents 5 to 7). However, these solvents must be used in combination with a non-polar organic solvent or alcohol and water. However, the introduction of large amounts of alcohol or water with active hydrogen can lead to side reactions such as hydrolysis of dianhydrides or the hydrolysis of polyamic acid, which is the precursor of the polyimide. This can easily cause problems such as the inability to avoid whitening of the polyimide precursor solution and the inability to achieve high molecular weight polyimide precursors.

[0005] Furthermore, although polyurethane is a plastic material, it is as soft as rubber and possesses excellent tensile strength, abrasion resistance, elasticity, and oil resistance. It is used in a wide range of industrial products, from athletic shoe soles and clothing to soundproofing, insulation, and adhesives, as well as automotive materials such as bumpers and headrests. The synthesis of polyurethanes can be achieved through various methods depending on their structure and intended use. Since urethane esterification is an exothermic reaction, most thermoplastic polyurethanes are stably synthesized by solution polymerization. Especially for high molecular weight polyurethanes, DMF is often used as a polar solvent that can uniformly dissolve the resulting polyurethane. However, as mentioned earlier, the safety concerns associated with DMF remain a concern.

[0006] As described above, the solvent described below is not yet known. This solvent is suitable for synthesizing polyimide precursors, polyamide-imide precursors, and other polyamic acids, polyimides, polyamide-imides, polyurethanes, etc. It can efficiently and stably synthesize high molecular weight polymers. The reaction solution does not become cloudy during or after the reaction, has high transparency and storage stability, and can obtain synthetic resins with excellent adhesion to the substrate.

[0007] [Existing Technical Documents]

[0008] [Patent Literature]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2016-194025.

[0010] [Patent Document 2] Japanese Patent Application Publication No. 2013-023583.

[0011] [Patent Document 3] Japanese Patent Publication No. 2017-517582.

[0012] [Patent Document 4] Japanese Patent Application Publication No. 2015-511935.

[0013] [Patent Document 5] Japanese Patent Application Publication No. 2017-149796.

[0014] [Patent Document 6] Japanese Patent Application Publication No. 2017-061603.

[0015] [Patent Document 7] Japanese Patent Application Publication No. 2017-052877. Summary of the Invention

[0016] [The technical problem the invention aims to solve]

[0017] The technical problem to be solved by the present invention is to provide a solvent and a method for manufacturing the synthetic resin using the solvent. The solvent can efficiently and stably synthesize high molecular weight polymers. The reaction solution does not turn cloudy during and after the reaction, has high transparency and storage stability, and can obtain synthetic resins with excellent adhesion to substrates. It is suitable for synthesizing polyimide precursors, polyamide-imide precursors, and other polyamic acids, polyimides, polyamide-imides, polyurethanes, etc.

[0018] [Methods used to solve problems]

[0019] In order to solve the aforementioned technical problem, the inventors of this case conducted repeated and dedicated research, and as a result, discovered a resin synthesis solvent (C) containing an amide solvent (A) and a reaction promoter (B), thus completing this invention.

[0020] That is, the present invention provides the following invention.

[0021] (1) A solvent (C) for resin synthesis, comprising 10% by mass to 99.9999% by mass of an amide solvent (A) and 0.0001% by mass to 5% by mass of a reaction promoter (B), wherein the reaction promoter (B) is an aliphatic or aromatic tertiary amine compound having one or more tertiary amino groups in its molecule.

[0022] (2) The resin synthesis solvent (C) as described in (1), wherein the amide solvent (A) is an alkoxy-N-substituted propionamide of general formula (1).

[0023] [Chemistry 1]

[0024]

[0025] (In the formula, R1 to R3 independently represent straight-chain alkyl groups with 1 to 22 carbon atoms, branched alkyl groups with 3 to 22 carbon atoms, alkyl ether groups with 2 to 22 carbon atoms, alicyclic hydrocarbon groups with 3 to 22 carbon atoms, and aromatic hydrocarbon groups with 6 to 22 carbon atoms, respectively, and R4 represents a hydrogen atom or a methyl group. In addition, the following cases are included: R2 and R3 are each independently hydrogen atoms (excluding the case where they are both hydrogen atoms), or together with the nitrogen atom carrying R2 and R3, they form a saturated 5-membered ring to a 7-membered ring (including the case of a ring with an oxygen atom)).

[0026] (3) The solvent (C) for resin synthesis as described in (1) or (2), wherein the reaction promoter (B) is an aliphatic or aromatic tertiary amine compound of general formula (2), having one or more tertiary amino groups in the molecule, and further having one or more functional groups selected from ether, ester and amide groups in the molecule.

[0027] (In the formula, A, B, and C independently represent straight-chain alkyl groups with 1 to 22 carbon atoms, branched alkyl or alkyl ether groups with 3 to 22 carbon atoms, alkyl ester groups, alkyl amide groups, alicyclic hydrocarbon groups with 3 to 22 carbon atoms, and aromatic hydrocarbon groups with 6 to 22 carbon atoms, substituents with ether groups represented by general formula (3), substituents with ester groups represented by general formula (4), and substituents with amide groups represented by general formula (5). (In the formula, R5, R7, and R9 represent straight-chain alkylene groups with 1 to 22 carbon atoms, branched alkylene groups or alkylene ether groups with 3 to 22 carbon atoms, alicyclic hydrocarbon groups with 3 to 22 carbon atoms, and aromatic hydrocarbon groups with 6 to 22 carbon atoms, respectively. R6, R8, R 10 and R 11 This refers to straight-chain alkyl groups having 1 to 22 carbon atoms, branched alkyl or alkyl ether groups having 3 to 22 carbon atoms, alkyl ester groups, alkyl amide groups, alicyclic hydrocarbon groups having 3 to 22 carbon atoms, and aromatic hydrocarbon groups having 6 to 22 carbon atoms. Additionally, R... 10 With R 11 Each can be independently a hydrogen atom, R 10 With R 11 It can also be used with R-carrying 10 With R 11 The nitrogen atoms together form saturated 5-membered to 7-membered rings (including rings with oxygen atoms).

[0028] [Chemistry 2]

[0029]

[0030] [Chemistry 3]

[0031] -R5-O-R6 General formula (3)

[0032] [Chemistry 4]

[0033]

[0034] [Chemistry 5]

[0035]

[0036] (4) The resin synthesis solvent (C) as described in any one of (1) to (3), wherein the resin synthesis solvent (C) further contains a stabilizer (D) and / or an ionic liquid, said stabilizer (D) being a compound having active hydrogen in its molecule.

[0037] (5) The resin synthesis solvent (C) as described in any one of (1) to (4) is used to synthesize polyimide precursors, polyamide-imide precursors, polyester-imide precursors, polyether-imide precursors, polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins, polyimide copolymers composed of any two or more precursors selected from the various resins, polyamide resins, polyurethane resins, polyester resins, polyacrylic resins, and fluoropolymers.

[0038] (6) A method for manufacturing a polyimide precursor, a polyamide-imide precursor and a method for manufacturing a polyimide by heating and imidizing the precursors, wherein an acid dianhydride is mixed with a diamine and / or a diisocyanate and polymerized using a resin synthesis solvent (C) as described in any one of (1) to (5).

[0039] (7) A method for manufacturing a polyurethane and a method for manufacturing a polyurethane dispersion in water, wherein a polyol and a diisocyanate are mixed and polymerized using a resin synthesis solvent (C) as described in any one of (1) to (5).

[0040] (8) A polyurethane dispersion containing a resin synthesis solvent (C) as described in any one of (1) to (5).

[0041] (9) A resin varnish selected from any one of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluororesin varnish, containing a resin synthesis solvent (C) as described in any one of (1) to (5).

[0042] (10) An adhesive resin comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluororesin varnish.

[0043] (11) An ink composition comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

[0044] (12) A photosensitive resin composition comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluororesin varnish.

[0045] (13) An adhesive resin composition comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

[0046] (14) A resin composition for lubricating coating, comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluororesin varnish.

[0047] (15) A heat-resistant coating comprising: a resin synthesis solvent (C) as described in any one of (1) to (5); and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, and fluoropolymer varnish.

[0048] [Invention Effects]

[0049] The resin synthesis solvent of the present invention contains an amide solvent (A) and a reaction promoter (B). By using this synthesis solvent as a reaction solvent in the synthesis of polyimide precursors, polyamide-imide precursors, etc., from acid dianhydrides with diamines and / or diisocyanates, various high-molecular-weight precursors (polyamic acids) can be obtained while these reactions proceed at a controllable high rate. The resulting polyamic acid solution exhibits excellent transparency, does not become cloudy even after long-term storage, and has good storage stability. Polyimide films, heat-resistant coatings, etc., with high transparency, high smoothness, and excellent mechanical strength can be easily manufactured using these various polyamic acid solutions. Furthermore, the resin synthesis solvent of the present invention can also be suitably used in the urethane esterification reaction of polyols and diisocyanates, enabling the acquisition of high-molecular-weight and high-performance polyurethanes while proceeding at a controllable high rate. Detailed Implementation

[0050] The embodiments of the present invention are described in detail below.

[0051] An embodiment of the present invention provides a resin synthesis solvent (C) containing an amide solvent (A) and a reaction promoter (B). The amide solvent (A) is a compound having one or more amide groups within its molecule, and the content of the amide solvent (A) relative to the resin synthesis solvent (C) is from 10% by mass to 99.9999% by mass. The amide solvent (A) is preferably a compound that does not have active hydrogen and / or functional groups that react with active hydrogen within its molecule. Furthermore, when the content of the amide solvent (A) is 80% by mass or more, in order to maintain the fluidity of the resin synthesis solvent (C) at the reaction temperature, it is more preferable that the amide solvent (A) is a liquid in a temperature range of 0°C to 140°C.

[0052] The amide solvent (A) is not particularly limited, but is preferably a compound with low risk or harm to human health, ecology or environment, and more preferably a highly safe compound that has no impact on human health, ecology or environment. Examples of such compounds include: N-alkyl (4 or more carbons)-2-pyrrolidone (N-butyl-2-pyrrolidone, N-hexyl-2-pyrrolidone, etc.), N-alkyl (1 or more carbons) alkyl (2 or more carbons) amides (N-ethylhexylamide, N-butylbutyramide, etc.), N,N-dialkyl (1 or more carbons) alkyl (2 or more carbons) amides (N,N-dimethylbutyramide, N,N-diethylbutyramide, N,N-dimethyloctylamide, etc.), alkoxy (1 or more carbons)-N-alkyl ((1 or more carbons) alkyl (2 or more carbons) amides (ethoxy-N-methylpropionamide, hexoxy-N-ethylbutyramide, etc.), alkoxy (1 or more carbons)-N,N-dialkyl ((1 or more carbons) alkyl (2 or more carbons) amides (methoxy-N, N-Dimethylpropionamide, ethoxy-N,N-dimethylbutyramide, lauroxy-N,N-dimethylpropionamide, phenoxy-N,N-methylethylpropionamide, etc.), alkanoyl (2 or more carbons) morpholines (propionylmorpholine, butyrylmorpholine, hexanoylmorpholine, octanoylmorpholine, etc.), alkanoyl (1 or more carbons) alkanoyl (2 or more carbons) morpholines (methoxyacetylmorpholine, 4-(3-methoxypropionyl)morpholine, etc.), N,N-dialkyl (2 or more carbons) acetamides (N,N-diethylacetamide, N,N-dipropylacetamide, N,N-diisopropylacetamide, N,N-dibutylacetamide, N,N-diisobutylacetamide, N,N-dihexylacetamide, etc.). These amide solvents (A) can be used alone, or in combination of two or more.

[0053] The amide solvent (A) is preferably alkoxy-N-substituted propionamide and alkoxy-N,N-disubstituted propionamide as shown in the following general formula (1) (where R1 to R3 independently represent a straight-chain alkyl group having 1 to 22 carbon atoms, a branched alkyl group having 3 to 22 carbon atoms, an alkyl ether group having 2 to 22 carbon atoms, an alicyclic hydrocarbon group having 3 to 22 carbon atoms, or an aromatic hydrocarbon group having 6 to 22 carbon atoms, respectively, and R4 represents a hydrogen atom or a methyl group. Additionally, it includes cases where R2 and R3 are each independently hydrogen atoms (excluding cases where both are hydrogen atoms), or where they form a saturated 5-membered to 7-membered ring (including cases with an oxygen atom) together with the nitrogen atom carrying R2 and R3). This is because alkoxy-N-substituted propionamide and alkoxy-N,N-disubstituted propionamide are industrially manufactured and further possess both ether and amide groups within the molecule, resulting in excellent solubility for various synthetic resins and the raw materials for these synthetic resins.

[0054] [Chemistry 6]

[0055]

[0056] The alkoxy-N-substituted propionamides and alkoxy-N,N-disubstituted propionamides are compounds formed by any combination of the functional groups represented by R1, R2, and R3. Examples include: methoxy-N-methylpropionamide (where R1 and R2 are methyl and R3 is a hydrogen atom), methoxy-N,N-dimethylpropionamide (where all R1, R2, and R3 are methyl), 3-methoxy-N,N-diethylpropionamide (where R1 is methyl and R2 and R3 are ethyl), butoxy-N,N-dimethylpropionamide (where R1 is butyl and R2 and R3 are methyl), lauroxy-N,N-dimethylpropionamide (where R1 is lauryl and R2 and R3 are methyl), stearoxy-N-ethylpropionamide (where R1 is stearyl, R2 is a hydrogen atom, and R3 is ethyl), and phenoxy-N,N-methylethylpropionamide (where R1 is phenyl, R2 is methyl, and R3 is ethyl). (The following are examples of different types of propionamide): ethoxy-N-phenylpropionamide (R1 is ethyl, R2 is hydrogen, R3 is phenyl), methoxy-N-cyclohexylpropionamide (R1 is methyl, R2 is cyclohexyl, R3 is hydrogen), isooctoxy-N-ethoxyethylpropionamide (R1 is isooctyl, R2 is hydrogen, R3 is ethoxyethyl), cyclohexyloxy-N,N-methylpropionamide (R1 is cyclohexyl, R2 is methyl, R3 is phenyl). Examples include oleyl (9Z)-octadec-9-en-1-yl (9Z)-octadec-9-en-1-yl), 3-isopropoxy-N,N-dimethylpropionamide (where R1 is isopropyl and R2 and R3 are methyl), and 4-(3-methoxypropionyl)morpholine (where R1 is methyl and R2 and R3 together with the nitrogen atom carrying R2 and R3 form a saturated 6-membered ring with an oxygen atom). These compounds can be used alone or in combination with two or more.

[0057] In addition, alkoxy-N-substituted propionamide and alkoxy-N,N-disubstituted propionamide are of general formula (6) (where R 12 R represents a straight-chain alkyl group having 1 to 18 carbon atoms or a branched alkyl group having 3 to 18 carbon atoms. 13 and R 14 Each of the following independently represents a hydrogen atom, or a straight-chain alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 3 to 6 carbon atoms (excluding cases where both are hydrogen atoms), R 15 In the case of compounds represented by hydrogen atoms or methyl groups, inexpensive industrial raw materials are readily available, and because they have a low steric hindrance structure, they can be industrially manufactured in high yields, thus making them preferred. Furthermore, methoxy-N,N-dimethylpropionamide and butoxy-N,N-dimethylpropionamide are highly safe for workers and the environment and are usually treated as industrial products, therefore they are particularly preferred.

[0058] [Chemistry 7]

[0059]

[0060] The reaction promoter (B) in this invention is a compound having one or more tertiary amino groups within its molecule. The substituents of the amino group in the reaction promoter (B) are not particularly limited; they can be aliphatic or aromatic, and can be chain-like or cyclic, with or without unsaturated groups. Furthermore, when the reaction promoter (B) does not have hydrogen atoms bonded to heteroatoms within its molecule, it does not undergo side reactions with acid dianhydrides or isocyanate compounds used as raw materials for synthesizing resins, thus enabling the production of high molecular weight synthetic resins in a short time, which is preferred. When using a resin synthesis solvent (C) for the resin synthesis reaction, choosing a reaction promoter (B) with a boiling point higher than the reaction temperature ensures that it does not volatilize during the reaction and can efficiently promote the reaction, which is also preferred. Examples of reaction promoters (B) include: trialkyl (one or more carbon atoms, which may be the same or different) amines, dialkyl (one or more carbon atoms, which may be the same or different) cyclohexylamines, tricyclohexylamines, and other aliphatic tertiary amines; dialkyl (one or more carbon atoms, which may be the same or different) aniline, dialkyl (one or more carbon atoms, which may be the same or different) 2,4,6-trimethylaniline, N-methyldiphenylamine, triphenylamines, and other aromatic tertiary amines; and N,N-dimethylbenzylamine, N-methyldibenzylamine, and other aliphatic tertiary amines having aromatic substituents. These reaction promoters (B) may be used alone or in combination with two or more.

[0061] The reaction promoter (B) is more preferably to have one or more functional groups selected from ether, ester, and amide groups within its molecule. By having these functional groups, there is a tendency for the reaction promoter (B) to have a greater promoting effect on the reaction (increased reaction rate and / or increased molecular weight of the resulting polymer). While the mechanism related to these effects is unclear, the inventors speculate that the reason lies in the increased polarity of the reaction promoter (B) due to the coexistence of ether, ester, or amide groups.

[0062] The reaction promoter (B) containing an ether group within the molecule (hereinafter also referred to as "reaction promoter (b1)" or simply "b1") is not particularly limited, as long as it has one or more ether groups among any substituents present in the tertiary amino group. Furthermore, these ether groups can be formed in a chain structure or a cyclic structure. Examples include: (methoxyethyl)diethylamine, N,N-dimethyldimethoxymethylamine, (ethoxyethyl)dibutylamine, (methoxyhexyl)ethylhexylamine, (methoxyethyl)diphenylamine, di(methoxyethyl)cyclohexylamine, tri(butoxymethyl)amine, etc. These reaction promoters (b1) can be used alone, or in combination of two or more.

[0063] The reaction promoter (B) containing an ester group within the molecule (hereinafter also referred to as "reaction promoter (b2)" or simply "b2") is not particularly limited, as long as it has one or more ester groups among any of the substituents present in the tertiary amino group. Furthermore, these ester groups can be formed in a chain structure or a cyclic structure. Examples include: methyl 3-methoxypropionate, methyl dimethylaminopropionate, butyl dimethylaminopropionate, methyl dibutylaminopropionate, butyl dibutylaminopropionate, ethyl diethylaminobutyrate, butyl ethylhexylaminoacetate, isopropyl morpholinopropionate, ethyl methylbenzylaminolaurate, etc. These reaction promoters (b2) can be used alone, or in combination of two or more.

[0064] Reaction promoters (B) containing an amide group (hereinafter also referred to as "reaction promoter (b3)" or simply "b3") exclude amide solvents (A) and are not particularly limited, as long as they have one or more amide groups among any substituents of the tertiary amino group. Furthermore, these amide groups can be formed in a chain structure or a cyclic structure. Examples include: dimethylamino-N,N-dimethylpropionamide, dimethyl-N,N-dibutylaminopropionamide, dibutylamino-N,N-dimethylpropionamide, dibutylamino-N,N-dibutylpropionamide, diethylamino-N,N-dimethylbutyramide, ethylhexylamino-N,N-diethylacetamide, morpholinopropionic acid morpholide, methylbenzylamino-N,N-dimethyllauramide, N,N-dimethylpropionamide, etc. These reaction promoters (b3) can be used alone or in combination with two or more.

[0065] The reaction promoters (b1) having an ether group, (b2) having an ester group, and (b3) having an amide group can be used individually or in combination with one or more of these reaction promoters.

[0066] The resin synthesis solvent (C) of this embodiment contains an amide solvent (A), and the content of the amide solvent (A) is from 10% by mass to 99.9999% by mass relative to the total amount of the resin synthesis solvent (C). The content of the amide solvent (A) is preferably from 20% by mass to 99.99% by mass, more preferably from 30% by mass to 99.8% by mass. If the resin synthesis solvent (C) contains 10% by mass or more of the amide solvent (A), it has sufficient solubility for various resin synthesis raw materials and the resulting synthetic resin, which is therefore preferred. Furthermore, when the amide solvent (A) contains 99.9999% by mass or less, it may contain 0.0001% by mass or more of a reaction promoter (B), which is an essential component of the resin synthesis solvent (C), and the reaction-promoting effect brought about by the reaction promoter (B) can be confirmed, which is therefore preferred.

[0067] The resin synthesis solvent (C) of this embodiment contains a reaction promoter (B) in addition to an amide solvent (A). The content of the reaction promoter (B) is 0.0001% to 5% by mass relative to the total content of the resin synthesis solvent (C). If the resin synthesis solvent (C) contains 0.0001% or more of the reaction promoter (B), it can promote the resin synthesis reaction, which is therefore preferred. On the other hand, if the content of the reaction promoter (B) exceeds 5% by mass relative to the total content of the synthesis solvent (C), it may be difficult to control the reaction rate, which is not preferred. The reaction promoter (B) has a tertiary amino group, and therefore readily forms a neutral salt with the carboxyl group generated during resin synthesis. By protecting the carboxyl group of polyamic acid, which is a polyimide precursor and a polyamide-imide precursor, in the form of a neutral salt, the transparency and storage stability of these precursor solutions are improved. This neutralizing salt can evaporate during the heating and imidization of the precursor, and high molecular weight polyimide resins and polyamide-imide resins are obtained through the imidization reaction of the deprotected carboxylate group. In view of these points, the content of the reaction promoter (B) is preferably 0.001% to 2% by mass, more preferably 0.01% to 1% by mass, relative to the total amount of solvent (C) used in resin synthesis.

[0068] Furthermore, regarding the content of the reaction accelerators (b1), (b2), and (b3) that may be contained in the reaction accelerator (B), since b1, b2, and b3 can be used individually, their content relative to the total solvent (C) for resin synthesis is 0.0001% to 5% by mass, respectively. However, when two or more of b1, b2, and b3 are mixed, the total content of these reaction accelerators relative to the total solvent (C) for resin synthesis does not exceed 5% by mass.

[0069] The reaction promoter (B) is preferably a reaction promoter (b3) containing an amide group within the molecule. It can be considered that by having one or more amino groups and one or more amide groups, the overall polarity of the molecule is increased, and the promoting effect of the amino group on the reaction is enhanced due to the influence of the amide group. Alternatively, through the interaction between the amide group and the amino group within the molecule of b3, the promoting effect of the amide group on the reaction is generated in addition to the amino group. Furthermore, depending on the type of raw materials or products used in resin synthesis, the feed ratio of various raw materials, reaction temperature, or reaction time, and further according to the desired molecular weight of the synthesized resin, b3 can be mixed with a reaction promoter (b2) containing an ester group, or b3 can be mixed with a reaction promoter (b1) containing an ether group, or b3 can be mixed with both b2 and b1.

[0070] As one embodiment of the solvent (C) for resin synthesis, an amide solvent (A) can be used in conjunction with other solvents. Examples of other solvents include: aromatic hydrocarbon solvents such as xylene, solvent naphtha, toluene, ethylbenzene, and tetrahydronaphthalene; urea solvents containing urea groups such as 1,3-dimethylurea, 1,3-diethylurea, 1,3-diphenylurea, 1,3-dicyclohexylurea, tetramethylurea, tetraethylurea, 2-imidazolinone, propylene urea, 1,3-dimethyl-2-imidazolinone, and N,N-dimethylpropylene urea; lactone solvents such as β-propiolactone, γ-butyrolactone, α-acetyl-γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone; and dibutyl ether, diethylene glycol monomethyl ether, and diethylene glycol. Ether solvents, ketone solvents, and ester solvents such as monoethyl ether, ethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 1,4-dioxane, 2-methyltetrahydrofuran, cyclopentylmethyl ether, 4-methyltetrahydropiperanone, acetophenone, acetylacetone, butyl acetate, ethyl benzoate, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, ethyl acetoacetate, isoamyl acetate, n-amyl acetate, and ethyl propionate; and general-purpose solvents such as 1,3-dioxolane, dimethyl sulfoxide, and nitrobenzene. These solvents can be used alone as other solvents, or in combination with two or more.

[0071] The content of other solvents relative to the total solvent (C) for resin synthesis is 89.9999% by mass or less, preferably 5% to 50% by mass, and more preferably 10% to 30% by mass. In the case of containing 89.9999% or less of other solvents, it may contain 10% or more of an amide solvent (A) as an essential component of the solvent (C) for resin synthesis, and 0.0001% or more of a reaction promoter (B). This allows for confirmation of the high solubility of the amide solvent (A) for various raw materials used in resin synthesis and the resulting synthetic resin, as well as the reaction-promoting effect of the reaction promoter (B), and is therefore preferred.

[0072] In one embodiment, the boiling point of the amide solvent (A) and other solvents is preferably between 80°C and 400°C at atmospheric pressure. Furthermore, the boiling point of these solvents is more preferably between 100°C and 350°C at atmospheric pressure, and particularly preferably between 180°C and 280°C. If the boiling point of the solvent is less than 80°C, and the reaction is carried out at a temperature above 80°C during the resin manufacturing process, the concentration of the reaction solution changes due to solvent evaporation, making it difficult to reproduce the molecular weight and solution viscosity of the resulting resin precursor or synthetic resin. On the other hand, if the boiling point of the solvent exceeds 400°C, in the manufacturing process of forming a polyamic acid solution on a substrate such as a metal and then performing staged imidization at a temperature of 100°C to 500°C, sometimes the solvent does not completely evaporate and remains in large quantities in the resulting polyimide film or other products, or carbonizes in the product, resulting in reduced transparency, strength, elongation, heat resistance, and chemical resistance of the product.

[0073] As one embodiment of the solvent (C) for resin synthesis, an amide solvent (A) and an ionic liquid can be used together. Alternatively, the solvent (C) for resin synthesis can be used in combination with an amide solvent (A), other solvents, and an ionic liquid. In this invention, the ionic liquid is a salt composed of anions and cations, and is liquid in a temperature range of 0°C to 150°C. The ionic liquid has high polarity and excellent solubility for poorly soluble synthetic resins; therefore, by containing the ionic liquid, solutions of polyamic acid with higher transparency and stability can be obtained. Furthermore, the ionic liquid is non-volatile, flame-retardant, and has high thermal and chemical stability, high ionic conductivity, or excellent electrochemical properties. Therefore, it does not cause adverse effects in the high-temperature imidization reaction of polyamic acid. By containing trace amounts of the ionic liquid in products such as polyimide films, the products can be given softness, imidization reactions can be carried out at temperatures above the glass transition temperature, and heat resistance is further improved.

[0074] Ionic liquids can be classified according to the cations that form their basic framework, including: imidazolium salts, pyrrolidineonium salts, pyridinium salts, piperidinium salts, ammonium salts, and phosphonium salts. Furthermore, various ionic liquids can be selected by changing the type of anion in these salts, or by changing the substituents such as alkyl groups present in the cations and anions. Among these, imidazolium salts, pyrrolidineonium salts, pyridinium salts, piperidinium salts, and ammonium salts are preferred because they contain nitrogen atoms and exhibit basicity. This is likely because most amide solvents contained in the resin synthesis solvent (C) are neutral to weakly basic, and basic ionic liquids have good compatibility with amide solvents. Additionally, imidazolium salts and ammonium salts are readily available in high-purity industrial grades, making them even more preferred. These ionic liquids can be used individually or in combination of two or more.

[0075] The content of the ionic liquid is 20% by mass or less relative to the total solvent (C) used for resin synthesis, preferably 0.001% by mass to 10% by mass, and more preferably 0.01% by mass to 5% by mass. If the content of the ionic liquid exceeds 20% by mass, a large amount of ionic liquid will remain in the final product such as the polyimide film obtained by directly heating the polyamic acid solution. Furthermore, even if the polyamic acid solution is temporarily precipitated before imidization, there is a concern that a small amount of ionic liquid may remain in the final product, adversely affecting the quality of the product. On the other hand, by containing 0.001% by mass or more of ionic liquid, the final product such as the polyimide film can be provided with flexibility, elongation, and electrochemical properties, and is therefore preferred.

[0076] The solvent (C) for resin synthesis in this embodiment may further contain a stabilizer (D). The stabilizer (D) referred to in this specification is a compound containing active hydrogen in its molecule, specifically including water, alcohols, and amines. Because the stabilizer (D) contains active hydrogen in its molecule, it protects the reactive groups of these compounds by reacting with dianhydrides or diisocyanates used as raw materials for resin synthesis. This allows for the slowing down of the resin synthesis reaction rate or the prevention of turbidity or the formation of insoluble substances (gelling) in the reaction solution, enabling more precise control of the resin synthesis reaction rate, the molecular weight of the resin, and the stability of the resin solution. Especially in multi-stage reactions where the reaction conditions, such as temperature, are varied, the combined use of a reaction promoter (B) and a stabilizer (D) allows for smooth reaction over a wide temperature range, resulting in high molecular weight resins or resin solutions with high transparency and storage stability.

[0077] From the viewpoint of easy deprotection, the stabilizer (D) is preferably water, an alcohol with a boiling point below 140°C, or an amine with a boiling point below 140°C (rejected (B)). Furthermore, from the viewpoint of being easily removed from the reaction solution by distillation, the stabilizer (D) is more preferably water, an alcohol with a boiling point below 120°C, or an amine with a boiling point below 120°C (rejected (B)), and particularly preferably an alcohol with a boiling point below 100°C or an amine with a boiling point below 100°C (rejected (B)). One stabilizer (D) may be used alone, or two or more may be used in combination.

[0078] The alcohol used as stabilizer (D) is not particularly limited, as long as it contains a hydroxyl group. Monofunctional alcohols with only one hydroxyl group, difunctional alcohols with two hydroxyl groups, and polyfunctional alcohols with three or more hydroxyl groups can be used. Monofunctional alcohols are preferred because both protecting and deprotecting reactions are relatively easy to perform. Examples of monofunctional alcohols include methanol, ethanol, isopropanol, tert-butanol, 9-decen-1-ol, 1-octacosanol, diethylene glycol monomethyl ether, propylene glycol-1-monomethyl ether, 4-dimethylamino-1-butanol, cyclohexanol, and benzyl alcohol, which contain one primary or secondary hydroxyl group. Methanol, ethanol, n-propanol, isopropanol, n-butanol, and tert-butanol have boiling points below 120°C at normal pressure, allowing for deprotection at low temperatures, and are therefore more preferred. These alcohols can be used alone or in combination of two or more.

[0079] The amine used as stabilizer (D) is not particularly limited to primary or secondary amines that exclude the reactive promoter (B) from having an intramolecular amino group. Secondary amines are preferred because both protecting and deprotecting reactions are relatively easy to perform. Examples of secondary amines include dimethylamine, ethylmethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, dicyclohexylamine, diallylamine, piperidine, pyrrolidine, morpholine, N-methylbenzylamine, and dibenzylamine. Dimethylamine, ethylmethylamine, diethylamine, dipropylamine, diisopropylamine, diallylamine, piperidine, and pyrrolidine have boiling points below 120°C at ambient pressure, allowing for deprotection at low temperatures, and are therefore more preferred. These amines can be used alone or in combination of two or more.

[0080] Stabilizer (D) may be used alone or in combination with any one of the groups consisting of water, the various alcohols and the various amines mentioned above.

[0081] When using stabilizer (D), its mechanism of action is presumably different depending on the type of stabilizer (D) and the types of raw materials used in the resin synthesis reaction. For example, in the synthesis of polyimide precursors and polyimide resins from dianhydrides and diamines, the dianhydrides and diamines are first subjected to a ring-opening polyaddition reaction in a solvent to obtain polyamic acid (containing carboxyl and amide groups) as a polyimide precursor. Then, heating induces an intramolecular dehydration cyclization reaction of the polyamic acid (forming an imide group through the dehydration of the carboxyl and amide groups) to obtain polyimide. If water is present in the reaction system, one carboxyl anhydride group of the dianhydride will be hydrolyzed to generate two carboxyl groups, increasing the number of functional groups that can react with the amino group. The stoichiometry between the added diamine and the dianhydride is disrupted, and the degree of polymerization of the polyamic acid does not increase. Ultimately, high molecular weight polyimide resins cannot be obtained. Therefore, adding water as a stabilizer is not preferred. On the other hand, if an alcohol or amine is present in the reaction system, a carboxylic anhydride group reacts with the alcohol to generate a carboxylate group and a carboxylate ester group, or a carboxylic anhydride group reacts with the amine to generate a carboxylate group and a carboxylate amide group. The number of functional groups reacting with the amino group remains unchanged, resulting in polyamic acid with a high degree of polymerization that is partially substituted with amamide ester groups or partially substituted with amamide amide groups. Compared with the corresponding polyamic acid, polyamic esters and polyamamides have higher solution stability. Therefore, by adding alcohols or amines as stabilizers to the solvent used for resin synthesis, highly transparent and highly stable polyimide precursor solutions can be obtained. In addition, polyamic esters and polyamamides are imidized by heating, accompanied by the desorption of alcohols or amines, ultimately yielding high molecular weight polyimide resins. Therefore, in the case of synthesizing polyimide precursors and polyimide resins from dianhydrides and diamines, it is preferable to add alcohols or amines as stabilizers to the solvent.

[0082] Furthermore, when using stabilizer (D) to synthesize polyamide-imide precursors and polyamide-imide resins from acid dianhydrides and diisocyanates, the acid anhydride groups are hydrolyzed by the presence of a small amount of water in the reaction system to obtain carboxylate groups. The resulting carboxylate groups react with the isocyanate groups of the diisocyanate to generate amide groups. The degree of polymerization of the polyamic acid, which is the polyamide-imide precursor, does not decrease; instead, the reaction rate and molecular weight (degree of polymerization) increase. Additionally, if an alcohol or amine is present in the reaction system, the same effect as with the polyamide precursor reaction system is observed. Furthermore, alcohols or amines have a protective effect on the isocyanate groups; therefore, by protecting or deprotecting as needed, polyamide precursor solutions and polyamide-imide resins with higher transparency, higher stability, and higher molecular weight can be obtained. Therefore, when synthesizing polyamide-imide precursors and polyamide-imide resins from acid dianhydrides and diisocyanates, it is preferable to add water, alcohol, or amine as stabilizers to the solvent.

[0083] The content of stabilizer (D) can be appropriately varied depending on the type of resin synthesis reaction and the type of reaction accelerator (B) or stabilizer (D) used. It is preferably 10% to 500% by mass relative to the total amount of reaction accelerator (B). Within this range, the reaction rate within a predetermined temperature range can be easily controlled in the synthesis of precursors such as polyamide-imide and polyimide precursors, as well as in the synthesis of polyurethane. Furthermore, the content of stabilizer (D) is more preferably 20% to 300% by mass relative to reaction accelerator (B), and particularly preferably 50% to 200% by mass.

[0084] The solvent (C) for resin synthesis in this embodiment can be suitably used to synthesize polyimide precursors, polyamide-imide precursors, polyester-imide precursors, polyether-imide precursors, polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins, polyimide copolymers composed of any two or more of the above-mentioned resin precursors, polyamide resins, polyurethane resins, polyester resins, polyacrylic resins, and fluoropolymers.

[0085] Examples of acid dianhydrides used as precursors for polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins, and any of these include: pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, and 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride. Aliphatic tetracarboxylic anhydrides include dianhydrides such as bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-oxobisphthalic anhydride, 1,2,5,6-naphthalenetetracarboxylic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 9,9-bis(4-(3,4-dicarboxyphenoxy)phenyl)fluorene dianhydride, 2,3,6,7-naphthalenetetracarboxylic anhydride, 2,3,5,6-pyridinetetracarboxylic anhydride, 3,4,9,10-perylenetetracarboxylic anhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, and butanetetracarboxylic anhydride; and aliphatic tetracarboxylic anhydrides containing cyclic aliphatic groups such as 1,2,3,4-cyclopentanetetracarboxylic anhydride. These dianhydrides can be used alone, or in combination with two or more.

[0086] Examples of diamine compounds used as precursors to polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins, and any of these include: 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, benzidine, m-phenylenediamine, p-phenylenediamine, 1,5-naphthylenediamine, 2,6-naphthylenediamine, bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)ether, 1,4-bis(4-aminophenoxy)benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-di... Aromatic diamines include methyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2',3,3'-tetramethyl-4,4'-diaminobiphenyl, 3,3',4,4'-tetramethyl-4,4'-diaminobiphenyl, 2,2'-di(trifluoromethyl)-4,4'-diaminobiphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,2'-bis(trifluoromethyl)-5,5'-dihydroxybenzidine, 3,5-diaminobenzoic acid, 3,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, and compounds in which at least a portion of the hydrogen atoms of the aromatic ring are substituted with alkyl or halogen atoms; aliphatic diamines containing cyclic aliphatic groups, such as cyclohexyldiamine and methylene dicyclohexylamine. These diamine compounds can be used alone or in combination with two or more.

[0087] Diisocyanates used as raw materials for polyamide-imide resins or their precursors, and as raw materials for polyurethane resins, include, for example, aliphatic diisocyanates, aromatic diisocyanates, and aromatic aliphatic diisocyanates. These diisocyanate compounds can be used alone, or in combination of two or more.

[0088] Examples of aliphatic diisocyanates include: ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, 2,2'-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, decamethylene diisocyanate, butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 1,6,11-undecylene triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanoxymethyloctane, 2,5 Aliphatic diisocyanates include 7-trimethyl-1,8-diisocyanate-5-isocyanoxymethyl octane, bis(isocyanoxyethyl) carbonate, bis(isocyanoxyethyl) ether, 1,4-butanediol dipropyl ether-ω,ω'-diisocyanate, lysine isocyanoxymethyl ester, lysine triisocyanate, 2-isocyanoxyethyl-2,6-diisocyanate hexanoate, 2-isocyanoxypropyl-2,6-diisocyanate hexanoate, bis(4-isocyanate-n-butylene) pentaerythritol, and methyl 2,6-diisocyanate hexanoate.

[0089] In addition, examples of alicyclic diisocyanates with cyclic structures include: isophorone diisocyanate (IPDI), 1,3-bis(isocyanoxymethyl)cyclohexane or 1,4-bis(isocyanoxymethyl)cyclohexane or mixtures thereof (bis(isocyanoxymethyl)cyclohexane (H6XDI)), 4,4'-dicyclohexylmethane diisocyanate or 2,4'-dicyclohexylmethane diisocyanate or 2,2'-dicyclohexylmethane diisocyanate or mixtures thereof (H12MDI), 1,3-cyclohexylmethane diisocyanate, etc. Alkane diisocyanate or 1,4-cyclohexane diisocyanate or mixtures thereof, 1,3-bis(isocyanoxyethyl)cyclohexane or 1,4-bis(isocyanoxyethyl)cyclohexane, methylcyclohexane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, dimer acid diisocyanate, 2,5-diisocyanoxymethylbicyclo-[2,2,1]heptane or 2,6-diisocyanoxymethylbicyclo-[2,2,1]heptane 2-Isocyanoxymethyl-2-(3-isocyanoxypropyl)-5-isocyanoxymethylbicyclo-[2,2,1]-heptane, 2-isocyanoxymethyl-2-(3-isocyanoxypropyl)-6-isocyanoxymethylbicyclo-[2,2,1]-heptane, 2-isocyanoxymethyl-3-(3-isocyanoxypropyl)-5-(2-isocyanoxyethyl)-bicyclo-[2,2,1]-heptane, 2-isocyanoxy... Alicyclic diisocyanates such as methyl-3-(3-isocyanoxypropyl)-6-(2-isocyanoxyethyl)-bicyclo-[2,2,1]-heptane, 2-isocyanoxymethyl-2-(3-isocyanoxypropyl)-5-(2-isocyanoxyethyl)-bicyclo-[2,2,1]-heptane, and 2-isocyanoxymethyl-2-(3-isocyanoxypropyl)-6-(2-isocyanoxyethyl)-bicyclo-[2,2,1]-heptane.

[0090] Examples of aromatic diisocyanates include, for example, 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and mixtures of isomers of these toluene diisocyanates (TDI; tolylene diisocyanate), 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate, and any mixtures of isomers of these diphenylmethane diisocyanates (MDI; diphenylmethane diisocyanate), toluidine diisocyanate (TODI; toluidine diisocyanate), terephthalene diisocyanate, naphthalene diisocyanate (NDI; naphthalene diisocyanate), and other aromatic diisocyanates.

[0091] Examples of aromatic aliphatic diisocyanates include: 1,3-xylylene diisocyanate or 1,4-xylylene diisocyanate or mixtures thereof (XDI; xylylene diisocyanate), 1,3-tetramethylxylylene diisocyanate or 1,4-tetramethylxylylene diisocyanate or mixtures thereof (TMXDI; tetramethylxylylenediisocyanate), etc.

[0092] Specific examples of polyols used as raw materials for polyurethane resins include: polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, silicone polyols, fluorinated polyols, and vinyl monomer-modified polyols. These polyols can be used individually or in combination of two or more.

[0093] The resin synthesis solvent (C) of this embodiment exhibits excellent solubility for polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins and their precursors, as well as polyurethane resins, polyamide resins, polyacrylic acid resins, fluoropolymers, etc., and is therefore suitable as a solvent for the manufacture and dissolution of various resins. Furthermore, by using the resin synthesis solvent (C) of this embodiment, the synthesis reactions of the various resins can be completed in a short time. The reactions are easily carried out even at low temperatures and can be easily controlled even at high temperatures, resulting in resins with high molecular weight, high transparency, and good heat resistance and mechanical properties.

[0094] When using a resin synthesis solvent (C) to synthesize various resins, the synthesis can be carried out under known reaction conditions. That is, the reaction apparatus, raw materials and their feed ratio, the method of feeding the raw materials, the reaction temperature, the reaction time, the purification method, etc., are the same as in the prior art. In addition, regarding the reaction temperature, when synthesizing polyimide precursors, polyamide-imide precursors (hereinafter also referred to as polyamic acid), and polyurethanes, the reaction can be completed at even lower temperatures compared to the prior art. On the other hand, the dehydration imidization reaction of various precursors can be carried out at higher temperatures compared to the prior art, and resin products such as polyimides and polyamide-imides with higher heat resistance and higher chemical resistance can be obtained.

[0095] In the reaction for synthesizing polyimide precursors from acid dianhydride and diamine using the resin synthesis solvent (C) of one embodiment, the reaction temperature is -20°C to 80°C, preferably 0°C to 70°C, and more preferably 10°C to 60°C. In the reaction for synthesizing polyamide-imide precursors from acid dianhydride and diisocyanate, the reaction temperature is 40°C to 140°C, preferably 60°C to 130°C, and more preferably 80°C to 120°C. Regarding the synthesis of these precursors, if the reaction temperature is above the respective lower limit temperature, the reaction can proceed at a sufficiently high rate and be completed in a short time, thus resulting in good productivity. Furthermore, when the reaction temperature is below the respective upper limit temperature, the intramolecular imidization reaction of the generated polyamic acid is suppressed, the transparency of the polyamic acid solution improves, and there is no turbidity or precipitation of gel-like insoluble matter over time, resulting in good storage stability. Moreover, the reaction time for these reactions varies depending on the reaction temperature, typically ranging from 1 hour to 24 hours.

[0096] In the reaction of synthesizing polyurethane from polyol and diisocyanate using the resin synthesis solvent (C) of one embodiment, the reaction temperature is typically 20°C to 150°C, preferably 30°C to 120°C, and more preferably 40°C to 110°C. Because of the presence of a reaction promoter (B), the urethane esterification reaction can proceed even at a low temperature of around 20°C, and high molecular weight polyurethane can be obtained. Furthermore, if an alcohol or amine is present as a stabilizer, the isocyanate groups of the diisocyanate are protected, suppressing the self-polymerization of diisocyanate caused by heating (uretidione formation or isocyanurate esterification, etc.) and the side reactions of diisocyanate with amide solvents at high temperatures, thus obtaining an ungelled high molecular weight polyurethane solution. The resulting polyurethane solution has low viscosity and can be suitable for use as an adhesive resin in coating agents, inks, adhesives, etc.

[0097] A polyurethane resin solution containing the synthesis solvent (C) prepared in one embodiment is added to water to disperse the polyurethane resin in the water, thereby producing polyurethane dispersions (PUDs). PUDs are widely used in environmentally friendly, low-VOC (Volatile Organic Compounds) water-based coatings, adhesives, inks, and coating agents. Since the organic solvents contained in PUDs require water solubility and excellent safety, the resin synthesis solvent (C) is considered the most suitable solvent for synthesizing polyurethane resins for PUDs. In PUDs containing the resin synthesis solvent (C), the isocyanate groups are protected by a stabilizer (D), resulting in excellent storage stability. Even during long-term storage, no second-layer separation or formation of insoluble substances (gelling) occurs, and it can be stored in a wide temperature range from -20°C to 80°C. Furthermore, the amide groups of the amide solvent (A) in the resin synthesis solvent (C) exhibit excellent adhesion to various substrates ranging from rubber and plastics to metals. Therefore, PUDs are suitable as steel plate treatment agents for various steel plates, such as molten galvanized steel plates, electro-galvanized steel plates, hot-rolled steel plates, and cold-rolled steel plates; suitable as rubber coating agents; and suitable as coating agents and primers for films and substrates made of polyethylene terephthalate, polycarbonate, polyacrylic acid, polyvinyl chloride, and polyamide. The polyurethane resin manufactured by this invention can be polymerized, and the viscosity of PUDs prepared from this polyurethane resin can be adjusted arbitrarily according to the purpose. It can be applied to various printing methods such as inkjet printing, screen printing, flexographic printing, and gravure printing, and can be used as a binder for printing inks on fabrics (dyeing), films, and sheets.

[0098] The polyimide precursor solution (also known as polyamic acid solution or resin varnish) manufactured using the resin synthesis solvent (C) of this embodiment exhibits good stability during long-term storage (transportation or storage) or use (manufacturing of polyimide molded articles). The polyimide precursor solution obtained using the resin synthesis solvent (C) can be used as an adhesive resin in coatings for forming polyimide molded articles or polyamide-imide molded articles, inks, insulating protective films, conductive inks, photosensitive resins, heat-resistant coatings, etc. In addition, the coating liquid for forming polyimide molded bodies can be used to form a coating of the required thickness on a metal or glass substrate by conventional film-forming methods (spin coating, dip coating, solvent casting, slot die coating, spraying, roller coating, etc.), and then be used for forming polyimide films, polyimide sheets, polyamide-imide heat-resistant coatings, lubricating coatings, metal bonding adhesives, liquid crystal alignment films, and other molded bodies by staged heating and imidization.

[0099] The resin synthesis solvent (C) of this embodiment can be used to manufacture polyimide films. The manufacturing method is not particularly limited, but examples include: forming a coating on a metal or glass substrate using a polyimide varnish (polyimide precursor solution, partially imidized polyimide precursor solution) or a polyimide resin solution (solution of soluble polyimide resin) synthesized using the resin synthesis solvent (C), followed by imidization through staged heat treatment at a temperature of 100°C to 500°C using a high-temperature convection oven or similar equipment. The heat treatment is performed in an inert gas atmosphere such as nitrogen at 100°C to 300°C for 10 to 60 minutes, at 300°C to 400°C for 30 to 60 minutes, and at 400°C to 500°C for 5 to 30 minutes. Preferably, the heat treatment is performed at 100°C to 150°C for 10 to 30 minutes, at 220°C to 250°C for 10 to 30 minutes, at 350°C for 30 minutes, and at 450°C for 10 minutes. Polyimide films heat-treated at these temperatures and times can completely remove the solvent in stages, exhibiting high transparency and high heat resistance.

[0100] Polyimide particles can be manufactured using the resin synthesis solvent (C) of this embodiment. The manufacturing method is not particularly limited, but examples include: imidization by stirring and periodically heating the polyimide varnish (polyimide precursor solution, partially imidized polyimide precursor solution) synthesized using the resin synthesis solvent (C) at a temperature of 50°C to 300°C to disperse and precipitate insoluble polyimide particles; and imidization by adding the polyimide varnish synthesized using the resin synthesis solvent (C) to a high-boiling-point non-polar solvent (unfavorable solvent), and imidizing it by ultrasonic irradiation or by stirring and periodically heating it at a temperature of 50°C to 300°C to disperse and precipitate insoluble polyimide particles. Examples of high-boiling-point non-polar solvents include xylene, acetophenone, ethyl benzoate, benzyl benzoate, and tetrahydronaphthalene. Here, the term "staged heating from 50°C to 300°C" refers to heating at 50°C to 200°C for 30 to 120 minutes, at 200°C to 300°C for 10 to 60 minutes, preferably at 70°C for 60 minutes, at 120°C for 60 minutes, and at 240°C for 30 minutes. The polyimide particles produced by these methods are preferably further heat-treated at 350°C for 120 minutes after being pulverized by centrifugation or vacuum drying.

[0101] The polyimide particles obtained by the manufacturing method of this invention, like polyimide resin, possess high heat resistance, solvent resistance (chemical resistance), and excellent electrical insulation properties, and are widely used in high-tech industries such as electrical and electronic technology fields, and aerospace technology fields. For example, it is anticipated that they will be used in composite materials such as powder toner additives for image forming, coatings for electrically insulating parts, fillers for molding, spacers for liquid crystals, and additives for heat-resistant coatings or lubricants.

[0102] By using the resin synthesis solvent (C) of the present invention, high-quality polyimide varnishes, polyamide-imide varnishes, polyester-imide varnishes, polyether-imide varnishes, polyurethane resin varnishes, polyamide resin varnishes, polyacrylic resin varnishes, and fluoropolymer varnishes can be obtained. Furthermore, by appropriately heat-treating and molding these varnishes, high-quality polyimide, polyamide-imide, polyester-imide, polyether-imide, polyurethane, polyamide, polyacrylic, and fluoropolymer resins, films, particles, etc., can be obtained. These resins, films, particles, and other molded bodies can be suitable for use as polyimide films or polyimide sheets, insulating films, heat-resistant films, IC (Integrated Circuit) packages, adhesive films, liquid crystal alignment films, resist films, planarization films, microlens array films, wire coating films, optical fiber coating films, etc., as well as belt components for use in electrophotographic image forming apparatuses (e.g., intermediate transfer belts, transfer belts, fixing belts, transport belts, etc.).

[0103] [Example]

[0104] The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these examples. Furthermore, unless otherwise specified, "parts", "%", and " / " in the following text refer to mass.

[0105] The materials used in the embodiments and comparative examples are as follows.

[0106] (A) Amide solvents

[0107] A-1: N-Butyl-2-pyrrolidone

[0108] A-2: 3-Methoxy-N,N-Dimethylpropionamide (manufactured by KJ Chemicals, registered trademark "KJCMPA")

[0109] A-3: 3-Butoxy-N,N-Dimethylpropionamide (manufactured by KJ Chemical Company, registered trademark "KJCBPA")

[0110] A-4: 3-Lauryloxy-N,N-Dimethylpropionamide

[0111] A-5: 3-Methoxy-N,N-Diethylpropionamide

[0112] A-6: 3-Ethoxy-N-phenylpropionamide

[0113] A-7: 3-Methoxy-N-cyclohexylpropionamide

[0114] A-8: N,N-Diethylbutyramide

[0115] A-9: N-propionylmorpholine

[0116] A-10: 4-(3-Methoxypropionyl)morpholine

[0117] A-11: N,N-Diisopropylacetamide

[0118] A-12: 3-Isopropoxy-N,N-Dimethylpropionamide

[0119] (B) Reaction Accelerator

[0120] B-1: Tributylamine

[0121] B-2: Triethylenediamine

[0122] b1-1: (Methoxyethyl)diphenylamine

[0123] b1-2: N,N-Dimethyldimethoxymethylamine

[0124] b2-1: Methyl dimethylaminopropionate

[0125] b2-2: Butyl dibutylaminopropionate

[0126] b2-3: Methyl 3-methoxypropionate

[0127] b3-1: Dibutylamino-N,N-dimethylpropionamide

[0128] b3-2: Morpholinylpropionylmorpholin

[0129] b3-3: Dimethylamino-N,N-dimethylpropionamide

[0130] b3-4: N,N-Dimethylpropionamide

[0131] (D) Stabilizer

[0132] D-1: Water

[0133] D-2: Methanol

[0134] D-3: Isopropanol

[0135] D-4: Diethylamine

[0136] D-5: Pyrrolidine

[0137] (E) Ionic liquids

[0138] E-1: Tetrabutylammonium trifluoromethanesulfonate

[0139] E-2: 1-Methyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide

[0140] (F) Other solvents

[0141] F-1: 1,3-Dimethyl-2-imidazolinone

[0142] F-2: Dimethyl sulfoxide

[0143] F-3: γ-valerolactone

[0144] F-4: γ-Butyrolactone

[0145] F-5: N-Formylmorpholine

[0146] F-6: 4-Acetylmorpholine

[0147] F-7: Dipropylene glycol dimethyl ether

[0148] F-8: 4-Methyltetrahydropiperanone

[0149] F-9: Cyclopentylmethyl ether

[0150] F-10: Xylene

[0151] Example 1 (Synthesis and Evaluation of Polyimide Precursor Solution)

[0152] In a 1000 mL four-necked flask equipped with a stir bar, thermometer, dropping funnel, and nitrogen inlet tube, 350 g of C-1 (shown in Table 1) as solvent and 25.0 g (125 mmol) of 4,4'-diaminodiphenyl ether (ODA; oxydianiline) as a diamine compound were added. The solution was stirred at room temperature for 30 minutes while passing nitrogen gas through it. After obtaining a colorless and transparent solution, the temperature of the solution was raised to 80 °C, and while maintaining the temperature at 80 °C, 37.8 g (128 mmol) of 3,3',4,4'-biphenyl tetracarboxylic diandhydride (BPDA) as an acid dianhydride was slowly added. After further stirring at 80 °C for 1 hour, the solution was cooled to room temperature, and solvent C-1 (5 g) was added at a solids concentration of 15% by mass to obtain a colorless, transparent, viscous polyimide precursor solution (varnish). The transparency and presence of color in the obtained varnish were observed visually. Viscosity was measured and the number-average molecular weight of the polyimide precursor was analyzed using the methods described below. The results are shown in Table 1. Furthermore, the viscosity of the obtained varnish was measured after storage at 40°C for 30 days. The viscosity change over time was calculated using the following formula. The viscosity after storage and the viscosity change over time are shown in Table 1.

[0153] Viscosity change rate over time (%) = (Viscosity after 30 days - Initial viscosity) / Initial viscosity × 100%

[0154] [Viscosity Measurement]

[0155] The viscosity of the varnish was measured at 25°C using a cone-plate viscometer (RE550 model, manufactured by Toki Sangyo Co., Ltd.) according to JIS (Japanese Industrial Standards) K5600-2-3.

[0156] [Number Average Molecular Weight]

[0157] A Hitachi L6000 high-performance liquid chromatography (HPLC) system and a Hitachi ATT-8 data analysis unit were used. Two Gelpack GL-S300MDT-5 columns were used. The mobile phase was a solvent prepared by dissolving 0.06M phosphoric acid and 0.06M lithium bromide in a 1 / 1 (L / L) mixture of DMF and THF. The determination was performed at a sample concentration of 0.2% and a flow rate of 1.0 mL / min. The number-average molecular weight was calculated using a calibration curve based on polystyrene standard samples.

[0158] Fabrication and evaluation of polyimide films

[0159] The obtained polyimide precursor solution (varnish) was coated onto a glass substrate and subjected to heat treatment in a hot air dryer under nitrogen flow at 120°C for 10 minutes, 250°C for 10 minutes, and 350°C for 30 minutes. The laminate of the polyimide film and the glass substrate was immersed in water for 10 minutes, and the polyimide film was peeled off from the glass substrate and dried in a hot air dryer at 80°C for 10 minutes to obtain a colorless, transparent polyimide film with a thickness of approximately 10 μm. The appearance, light transmittance, strength, elongation, and coefficient of linear thermal expansion of the obtained polyimide film were evaluated using the following methods, and the results are shown in Table 1.

[0160] [Appearance of the polyimide film]

[0161] The obtained polyimide film is visually observed to confirm the occurrence of defects such as foaming or cracking, and the following criteria are used for evaluation.

[0162] ◎: It is pale yellow and transparent, and there is no foaming or cracking.

[0163] ○: Pale yellow to yellow, transparent, slightly bubbly or cracked.

[0164] △: Yellow or translucent, with several bubbles or ruptures.

[0165] ×: Yellow to brown or opaque, with many bubbles or cracks.

[0166] Transparency

[0167] The obtained polyimide film was left to stand overnight at 23°C and 50% relative humidity, and then the light transmittance was measured. The measurement was performed using a haze meter (NDH-2000, manufactured by Nippon Denshoku Kogyo) according to JIS K7105. Higher light transmittance indicates better transparency of the polyimide film.

[0168] [Tensile strength and tensile elongation]

[0169] The obtained polyimide film was cut into sample pieces with a length of 100 mm and a width of 10 mm. After standing for 24 hours at a temperature of 23°C and a relative humidity of 50%, a tensile testing machine (manufactured by ORIENTEC, Tensilon RTA-100) was used, with a clamp spacing of 50 mm, a tensile speed of 50 mm / min, and n=5. The higher the tensile strength, the higher the strength of the polyimide film. In addition, the higher the elongation, the higher the elongation of the polyimide film.

[0170] [Coefficient of linear thermal expansion]

[0171] The obtained polyimide film was cut into sample pieces with a length of 20 mm and a width of 2 mm. After standing overnight at 23°C and 50% relative humidity, the samples were measured using a thermomechanical analysis apparatus (SII Nano-Technology, EXSTAR6000) under a nitrogen flow. The measurement method was as follows: the temperature was increased from room temperature to 220°C at a rate of 5°C / min, then decreased from 220°C to room temperature, and then increased a second time at a rate of 5°C / min. The average coefficient of linear expansion was measured from 50°C to 200°C. The lower the average coefficient of linear expansion, the higher the heat resistance or dimensional stability.

[0172] Examples 2 to 12 and Comparative Examples 1 to 6

[0173] In Examples 2 to 12, except for the diamine, dianhydride, solvent (C-2 to C-12), and other components described in Tables 1 and 2, a polyimide precursor solution (varnish) with a solids concentration of 15% by mass was synthesized in the same manner as in Example 1, and a polyimide film was further prepared. The varnish and film obtained in the same manner as in Example 1 were evaluated, and the results are shown in Tables 1 and 2. In Comparative Examples 1 to 6, the diamine, dianhydride, solvent, and other components described in Table 3 were used to synthesize the polyimide precursor solution (varnish) and prepare the polyimide film in the same manner as in Example 1. The varnish and film obtained in the same manner as in Example 1 were evaluated, and the results are shown in Table 3.

[0174] [Table 1]

[0175]

[0176] ODA: 4,4′-Diaminodiphenyl ether

[0177] PDA: p-phenylenediamine

[0178] DACH: 1,4-Diaminocyclohexane

[0179] BPDA: 3,3′,4,4′-Biphenyltetracarboxylic dianhydride

[0180] ODPA: 4,4′-O-diphthalic anhydride

[0181] PMDA: Pyromellitic dianhydride

[0182] [Table 2]

[0183]

[0184] ODA: 4,4′-Diaminodiphenyl ether

[0185] PDA: p-phenylenediamine

[0186] DACH: 1,4-Diaminocyclohexane

[0187] BPDA: 3,3′,4,4′-Biphenyltetracarboxylic dianhydride

[0188] ODPA: 4,4′-O-diphthalic anhydride

[0189] PMDA: Pyromellitic dianhydride

[0190] [Table 3]

[0191]

[0192] ODA: 4,4′-Diaminodiphenyl ether

[0193] BPDA: 3,3′,4,4′-Biphenyltetracarboxylic dianhydride

[0194] *1: The resulting polyimide film is brittle and cannot be cut into pieces.

[0195] As shown in Tables 1 to 3, the results of the examples and comparative examples reveal that the resin synthesis solvent (C) of the embodiments of the present invention, by containing an amide solvent (A) and a reaction promoter (B), enables the reaction of the diamine compound with the acid dianhydride to proceed rapidly and stably, and can produce a highly transparent, colorless, low-viscosity polyimide precursor solution (varnish). Furthermore, the viscosity of the resulting varnish exhibits extremely low viscosity change over time, making it suitable for long-term storage or transportation. It has also been found that the polyimide film obtained using these varnishes possesses high transparency, high light transmittance, low colorfastness, and excellent strength, elongation, heat resistance, and dimensional stability. The effects of the present invention result from the excellent dissolving power of the amide solvent (A), a component of the resin synthesis solvent (C), and the synergistic effect of the reaction promoter (B) on promoting the reaction, and are not solely obtained by combining the amide solvent (A) or the reaction promoter (B) with other solvents.

[0196] Example 13 (Synthesis of polyamide-imide precursor solution)

[0197] In a 3L four-necked flask equipped with a stirrer, condenser, thermometer, and nitrogen inlet, 117.6 g (0.6 mol) of trimellitic anhydride (TMA), 128.8 g (0.4 mol) of diphenylsulfone tetracarboxylic dianhydride (DSDA), 250.2 g (1.0 mol) of 4,4'-diphenylmethane diisocyanate (MDI), and 500 g of solvent C-13 (as shown in Table 4) were fed in. The mixture was stirred and heated to 120°C, and reacted at 120°C for 6 hours. After the reaction was completed, the reaction solution was cooled to 80°C and diluted with solvent C-13 (660 g) to a solids concentration of 30% by mass, yielding a polyamide-imide precursor solution (varnish) as a colorless and transparent solution. The viscosity of the obtained precursor solution and the number-average molecular weight of the precursor were determined using the same method described above. The results are shown in Table 4.

[0198] Examples 14 to 24 and Comparative Examples 7 to 12

[0199] In Examples 14 to 24, the polyamide-imide precursor solution was synthesized in the same manner as in Example 13, except that the dianhydride, diisocyanate, solvent (C-14 to C-24), and other components described in Tables 4 and 5 were used. Similarly, in Comparative Examples 7 to 12, the polyamide-imide precursor solution was synthesized in the same manner as in Example 13, using the dianhydride, diisocyanate, solvent, and other components described in Table 6. The viscosity of the various precursor solutions and the number-average molecular weight of the precursors were measured using the same method described above, and the results are shown in Tables 4 to 6.

[0200] Coating preparation and evaluation

[0201] The obtained polyamide-imide precursor solution (varnish) was used as the test coating and applied to an aluminum substrate or copper foil with a thickness of 1.0 mm to form a dry film thickness of approximately 5 μm. The film was pre-dried at 80°C for 20 minutes and then calcined at 400°C for 10 minutes to obtain the coating film. The resulting coating film was used to evaluate its adhesion, flexural strength, acid resistance, alkali resistance, and steam resistance. The results are shown in Tables 4 to 6.

[0202] [Tightness]

[0203] A checkerboard pattern of 1 mm was created in the coating according to JIS-K5600, and a peel test was conducted using adhesive tape. The number of remaining checkerboard patterns was counted, and the adhesion was evaluated according to the following criteria.

[0204] ◎: 100 unstripped

[0205] ○: 95 to 99 not stripped

[0206] △: 70 to 94 not stripped

[0207] ×: 0 to 69 unpeeled

[0208] [Bending resistance]

[0209] When bending with the coated side (with attached aluminum plate) as the outside, the aluminum plate used for coating is clamped in the bending part, and the bending resistance is evaluated according to the number of plates that are clamped when cracks appear in the bending part, as per the following criteria.

[0210] ◎: 0 pieces

[0211] ○: 1 to 2 tablets

[0212] △: 3 to 5 pieces

[0213] ×: 6 pieces or more

[0214] [Acid Resistance]

[0215] The uncoated sample piece (with attached aluminum plate) was immersed in a 5% sulfuric acid solution and left to stand at room temperature for one week. The condition of the coating was then visually observed, and the acid resistance was evaluated according to the following criteria.

[0216] ○: No change

[0217] △: Bubbling is visible

[0218] ×: Coating peeling

[0219] [Alkali resistance]

[0220] The uncoated sample piece (with attached aluminum plate) was immersed in a 5% sodium hydroxide solution and left to stand at room temperature for one week. The condition of the coating was then observed visually, and the alkali resistance was evaluated according to the following criteria.

[0221] ○: No change

[0222] △: Bubbling is visible

[0223] ×: Coating peeling

[0224] [Steam resistance]

[0225] The coating (with the aluminum plate attached) was placed in an autoclave and exposed to steam at 120°C and pressurized to 2 atm for 100 hours. The adhesion was then evaluated in the same manner as above. The higher the adhesion, the higher the steam resistance.

[0226] [Table 4]

[0227]

[0228] TMA: Trimeric tricarboxylic anhydride

[0229] BTDA: 3,3′,4,4′-benzophenone tetracarboxylic dianhydride

[0230] DSDA: 3,3′,4,4′-Diphenylsulfone tetracarboxylic dianhydride

[0231] MDI: Diphenylmethane-4,4′-diisocyanate

[0232] TDI: Toluene diisocyanate

[0233] [Table 5]

[0234]

[0235] TMA: Trimeric tricarboxylic anhydride

[0236] BTDA: 3,3′,4,4′-benzophenone tetracarboxylic dianhydride

[0237] DSDA: 3,3′,4,4′-Diphenylsulfone tetracarboxylic dianhydride

[0238] MDI: Diphenylmethane-4,4′-diisocyanate

[0239] TDI: Toluene diisocyanate

[0240] [Table 6]

[0241]

[0242] TMA: Trimeric tricarboxylic anhydride

[0243] MDI: Diphenylmethane-4,4′-diisocyanate

[0244] *1: The varnish has hardened or precipitated, so evaluation experiments cannot be performed.

[0245] As shown in Tables 4 to 6, the results of the examples and comparative examples indicate that the resin synthesis solvent (C) of the embodiments of the present invention, by containing an amide solvent (A) and a reaction promoter (B), enables the reaction of diisocyanate compounds with acid dianhydrides to proceed stably and at a high reaction rate, and can produce a highly transparent, colorless, low-viscosity polyamide-imide precursor solution (varnish). Furthermore, the viscosity of the resulting varnish exhibits extremely low viscosity change over time, enabling it to withstand long-term storage or transportation. Moreover, by applying these varnishes to a metal substrate and sintering them at high temperatures of 300°C to 550°C, a high-performance coating film with excellent adhesion, flexural strength, acid resistance, alkali resistance, and vapor resistance can be obtained. The effects of the present invention are due to the excellent solubility of the amide solvent (A), a component of the resin synthesis solvent (C), and the synergistic effect of the reaction promoter (B) on promoting the reaction, and are not solely obtained by combining the amide solvent (A) or the reaction promoter (B) with other solvents. The coating thus obtained has heat resistance above the sintering temperature, therefore the various polyamide-imide precursor solutions (varnishes) obtained by the present invention can be suitably used as heat-resistant coatings.

[0246] Example 25 (Synthesis of polyurethane resin solution)

[0247] In a 2L four-necked flask equipped with a stirrer, condenser, and thermometer, 150.0 g (0.05 mol) of polypropylene glycol (PPG), 100.0 g (0.05 mol) of polyester polyol (PEs), 62.6 g (0.25 mol) of 4,4'-diphenylmethane diisocyanate (MDI), and 800 g of solvent C-25 (shown in Table 7) were added. The mixture was stirred and heated to 70°C, and reacted at 70°C for 2 hours to obtain a prepolymer. Then, 9.3 g (0.15 mol) of ethylene glycol (EG) was added, and the reaction was carried out at 60°C for 3 hours. The reaction solution was cooled to room temperature and diluted with solvent C-25 (490 g) to a solids (polyurethane resin) concentration of 25.0% by mass, yielding a polyurethane resin solution as a colorless and transparent solution. The viscosity of the obtained resin solution and the number-average molecular weight of the resin were determined using the same method described above, and are shown in Table 7.

[0248] Examples 26 to 36 and Comparative Examples 13 to 18

[0249] Except for the conditions described in Tables 7 to 9, the synthesis of polyurethane resins in Examples 26 to 36 and Comparative Examples 13 to 18 was carried out in the same manner as in Example 25. The viscosity of the various resin solutions and the number-average molecular weight of the resins were determined using the same method, and are shown in Tables 7 to 9.

[0250] Using the obtained polyurethane resin solution, a coating was prepared by the following method. The tensile strength (breaking strength) and elongation (breaking elongation) of the coating were determined by the same tensile test as described above, and are shown in Tables 7 to 9.

[0251] [Moisture permeability test and water pressure resistance test]

[0252] The obtained polyurethane resin solution was applied to nylon taffeta fabric that had undergone water-repellent treatment using a roll-on-knife coater to a thickness of 40 μm after drying, and then solidified in water for 2 minutes. The fabric was further washed by immersion in warm water at 50°C for 3 minutes and dried at 150°C for 1 minute to obtain a breathable and waterproof fabric with a polyurethane resin film. The moisture permeability of the obtained breathable and waterproof fabric was measured according to JIS L-1099 (A-1 method), and the water pressure resistance was measured according to JIS L-1092. These test results are shown in Tables 7 to 9.

[0253] [Table 7]

[0254]

[0255] PPG: Polypropylene glycol (number average molecular weight 3000, glycol type)

[0256] PEs: Polyester polyol (number average molecular weight 2000, diol type, P-2010 manufactured by Kuraray Co., Ltd.)

[0257] PC: Polycarbonate diol (number average molecular weight 2000, diol type, manufactured by Kuraray Co., Ltd., C-2090)

[0258] MDI: Diphenylmethane-4,4′-diisocyanate

[0259] TDI: Toluene diisocyanate

[0260] EG: Ethylene glycol

[0261] BD: 1,4-Butanediol

[0262] [Table 8]

[0263]

[0264] PPG: Polypropylene glycol (number average molecular weight 3000, glycol type)

[0265] PEs: Polyester polyols (number average molecular weight 2000, diol type, P-2010 manufactured by Kuraray Co., Ltd.)

[0266] PC: Polycarbonate diol (number average molecular weight 2000, diol type, manufactured by Kuraray Co., Ltd., C-2090)

[0267] MDI: Diphenylmethane-4,4′-diisocyanate

[0268] TDI: Toluene diisocyanate

[0269] EG: Ethylene glycol

[0270] BD: 1,4-Butanediol

[0271] [Table 9]

[0272]

[0273] PPG: Polypropylene glycol (number average molecular weight 3000, glycol type)

[0274] PEs: Polyester polyols (number average molecular weight 2000, diol type, P-2010 manufactured by Kuraray Co., Ltd.)

[0275] PC: Polycarbonate diol (number average molecular weight 2000, diol type, manufactured by Kuraray Co., Ltd., C-2090)

[0276] MDI: Diphenylmethane-4,4′-diisocyanate

[0277] TDI: Toluene diisocyanate

[0278] EG: Ethylene glycol

[0279] BD: 1,4-Butanediol

[0280] *1: Because a coating cannot be formed, evaluation experiments cannot be performed.

[0281] As shown in Tables 7 to 9, the resin synthesis solvent (C) of the embodiments of the present invention, by containing an amide solvent (A) and a reaction promoter (B), enables the reaction between polyol and diisocyanate to proceed stably, and the resulting polyurethane resin has a high molecular weight, enabling the manufacture of highly transparent, colorless polyurethane resin solutions. Furthermore, the viscosity of the resulting polyurethane resin solution exhibits extremely low viscosity change over time, enabling it to withstand long-term storage or transportation. Moreover, by coating these polyurethane resin solutions onto release paper or plastic sheets, high-strength and high-elongation coatings can be obtained; and by coating them onto nylon fabrics, water-resistant products such as breathable and water-resistant breathable waterproof fabrics can be manufactured. The effects of the present invention are due to the excellent solubility of the amide solvent (A), a component of the resin synthesis solvent (C), and the synergistic effect of the reaction promoter (B) on promoting the reaction, and are not solely obtained by combining the amide solvent (A) or the reaction promoter (B) with other solvents. In addition, the polyurethane resin system obtained by the present invention has excellent water resistance, so various polyurethane dispersions (PUDs) can be manufactured by dispersing it in water.

[0282] Examples 37 to 46 (lubricating coatings) and Comparative Examples 19 to 24

[0283] Various varnishes (polyimide precursor solutions, polyamide-imide precursor solutions) obtained in Examples 1 to 24 and Comparative Examples 1 to 12 were mixed with the solid lubricants and additives shown in Tables 10 and 11, and diluted with solvents used for each varnish to achieve a solids concentration of 15% by mass to prepare lubricating coatings. The coating properties and coatability of the prepared lubricating coatings were evaluated using the methods described below, and the results are shown in Table 10. Furthermore, a lubricating film was prepared from the lubricating coating using the methods described below, and the wear resistance and adhesion were evaluated, and the results are shown in Tables 10 and 11. In the tables, "MoS2" represents molybdenum disulfide (manufactured by Sumitomo Lubricants Co., Ltd., Molypowder PS, density 4.8 g / cm³). 3 "PTFE" indicates polytetrafluoroethylene (manufactured by Central Glass Co., Ltd., Cefral Lube), and "graphite" indicates flake graphite W-5 (manufactured by Ito Graphite Industry Co., Ltd., density 2.2 g / cm³). 3 “Epoxy resin” refers to phenolic varnish-type epoxy resin (manufactured by Shell Oil & Chemical Company, EPIKOTE 152).

[0284] Paintability

[0285] For the prepared lubricating coating, the dispersion state of the solid lubricant and the presence of agglomeration of the resin varnish (polyimide varnish, polyamide-imide varnish) are visually confirmed and evaluated according to the following criteria.

[0286] ◎: No agglomerates were observed in the mixing process and the prepared lubricating coating; the resin varnish dissolved and became homogeneous (practical level).

[0287] ○: Although the solid lubricant was not uniformly dispersed during the mixing process, there were no agglomerates in the final lubricating coating, and the varnish resin dissolved and became homogeneous (practical level).

[0288] ×: The varnish resin in the lubricating coating during the mixing process or after preparation may gel due to coagulation.

[0289] [Paintability]

[0290] Using the prepared lubricating coating, a 10 μm thick film was applied to the surface of a SUS316 disk (100 mm in diameter, 5 mm thick) by spray coating. The condition of the coated surface was visually confirmed and evaluated according to the following criteria.

[0291] ○: The coating is uniform and of good quality (practical level).

[0292] ×: The coating surface is uneven, with bumps and irregularities.

[0293] [Sliding properties (wear resistance)]

[0294] The prepared lubricating coating was sprayed onto the surface of a preheated SUS316 disk (100 mm in diameter, 5 mm thick) to a thickness of 10 μm. The coating was then dried at 100 °C for 10 minutes, at 200 °C for 10 minutes, and further heated at 400 °C for 1 hour to obtain a coating sample. A reciprocating sliding wear test was conducted using a steel ball (SUJ2) as the test material. The sliding test conditions were set at 15 mm / s and 100 cycles. After the sliding test, the wear depth of the coating was measured and evaluated according to the following criteria.

[0295] ◎: The wear depth of the part with the greatest consumption is less than 3μm (practical level).

[0296] ○: The wear depth of the part with the greatest consumption is more than 3μm to less than 5μm (practical level).

[0297] △: The wear depth of the part with the greatest consumption is more than 5μm to less than 7μm (practical level).

[0298] ×: The wear depth of the part with the greatest consumption is more than 7μm.

[0299] [Tightness]

[0300] The prepared lubricating coating was sprayed onto the surface of a SUS316 board (50mm diameter × 50mm, 5mm thickness) with a fixed coating thickness of 10μm. The coated surface was dried at 100°C for 10 minutes, at 200°C for 10 minutes, and then heated at 400°C for 1 hour to form a coating film. One hundred 1mm checkerboard patterns were created on the coating film according to JIS-K5600, and a peel test was performed using adhesive tape. The number of remaining checkerboard patterns was counted, and the adhesion was evaluated according to the following criteria.

[0301] ◎: 100 unstripped

[0302] ○: 95 to 99 not stripped

[0303] △: 70 to 94 not stripped

[0304] ×: 0 to 69 unpeeled

[0305] [Table 10]

[0306]

[0307] [Table 11]

[0308]

[0309] Examples 47 to 52 (adhesives) and Comparative Examples 25 to 28

[0310] Using a benchtop coating machine (TC-1, manufactured by Mitsui Electric Machinery Co., Ltd.), various varnishes (polyimide precursor solutions, polyamide-imide precursor solutions) obtained in Examples 1 to 24 and Comparative Examples 1 to 12 were applied to one side of a polyimide film (manufactured by RDS Corporation #15) with a dried thickness of 35 μm using a doctor blade coater. The film was then dried at 100°C for 10 minutes and at 200°C for 10 minutes to produce a cover lay film with an adhesive layer thickness of 35 μm. The obtained coating film (adhesive layer side) is placed on the copper foil on which the rust-proof metal layer has been removed (polyimide film / adhesive layer / copper foil), and pressed at a temperature of 400℃, a pressure of 1MPa, and a time of 1 minute. Then, it is heated in an oven at a temperature of 400℃ for 24 hours to obtain a laminate consisting of three layers: polyimide film / adhesive layer / copper foil.

[0311] To prepare a printed circuit board with a wiring width / spacing (L / S) of 1 mm / 1 mm, a polyimide copper-clad laminate (manufactured by Nippon Steel Chemical Co., Ltd., Espanex MC18-25-00FRM) is formed by circuit processing. The aforementioned cover film (adhesive layer side) is placed on the circuit surface of the printed circuit board (polyimide film / adhesive layer / printed board / adhesive layer / polyimide film), and pressed at a temperature of 400°C, a pressure of 1 MPa, and a time of 1 minute. Then, it is heated in an oven at a temperature of 400°C for 24 hours to obtain a wiring board with a cover film (a laminate consisting of five layers: polyimide film / adhesive layer / printed board / adhesive layer / polyimide film).

[0312] The adhesion strength of the obtained laminate was measured by the following method and evaluated according to the following criteria. The results are shown in Table 12. In addition, the heat resistance (dry and moisture resistance) of the solder on the obtained wiring board was evaluated by the following method. The results are shown in Table 12.

[0313] [Next intensity]

[0314] The laminate was cut into specimens with a width of 10 mm and a length of 100 mm. Using a tensile testing machine (manufactured by Toyo Seiki Co., Ltd., Strograph-M1), the polyimide film and copper foil were peeled off at a speed of 50 mm / min in the 180° direction. The peel strength was taken as the adhesion strength and evaluated according to the following criteria.

[0315] ◎: Above 0.35kN / m

[0316] ○: Above 0.2kN / m but below 0.35kN / m

[0317] ×: Not reaching 0.2kN / m

[0318] [Solder heat resistance (drying)]

[0319] After placing the obtained wiring board in a constant temperature and humidity bath at 105°C and 50% relative humidity for 1 hour, immerse it in a heated solder bath for 10 seconds, observe the bonding status, and confirm whether there are any defects such as foaming, bulging, or peeling. Evaluate according to the following criteria.

[0320] ○: Even at a solder bath temperature of 300℃, there were no defects such as foaming, bulging, or peeling.

[0321] ×: Defects such as foaming, bulging, and peeling may occur if the solder bath temperature does not reach 300℃.

[0322] [Solder heat resistance (moisture resistance)]

[0323] After placing the obtained wiring board in a constant temperature and humidity bath at 85°C and 85% relative humidity for 24 hours, immerse it in a heated solder bath for 10 seconds and observe the bonding status to confirm whether there are any defects such as foaming, bulging, or peeling.

[0324] ○: Even at a solder bath temperature of 280℃, there were no defects such as foaming, bulging, or peeling.

[0325] ×: If the solder bath temperature does not reach 280℃, defects such as foaming, bulging, and peeling may occur.

[0326] [Table 12]

[0327]

[0328] Examples 53 to 58 (photosensitive resin) and Comparative Examples 29 to 32

[0329] The various varnishes (polyimide precursor solutions) obtained in Examples 1 to 12 and Comparative Examples 1 to 6 were measured in solids of 10 g. 1.6 g of α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene 1,2-naphthoquinone diazide-5-sulfonate (manufactured by Toyo Synthetic Industries, TS150-A) as a quinone diazide compound and 0.42 g of WPAG-567 (manufactured by Fuji Film & Photonics Co., Ltd.) as a photoacid generator were added to obtain a photosensitive polyimide precursor composition. The obtained photosensitive polyimide precursor composition was coated onto a 6-inch silicon wafer with a pre-baked film thickness of 14 μm to 16 μm. Pre-baking was performed at 120°C for 2 minutes using a hot plate (a Mark-7 coating and developing apparatus manufactured by Tokyo Electron Co., Ltd.) to obtain a photosensitive resin film. Subsequently, a patterned, truncated reticle was set up in an exposure machine (GCA DSW-8000 i-ray stepper), and the exposure time was varied at an intensity of 365 nm. The resulting photosensitive resin film was exposed using i-rays (365 nm) from a mercury lamp. Using a Mark-7 developing apparatus manufactured by Tokyo Gosei Corporation, a 2.38% aqueous solution of tetramethylammonium hydroxide was sprayed onto the exposed film at 50 rpm for 10 seconds. Then, the film was allowed to stand at 0 rpm for 40 seconds, sprayed again for 10 seconds, and allowed to stand for 40 seconds. After that, the film was rinsed with water at 400 rpm and spun dry at 3000 rpm for 10 seconds to obtain the developed photosensitive resin film. The developed photosensitive resin film was heat-treated at 140°C for 30 minutes under a nitrogen flow (oxygen concentration below 20 ppm) using an inert oven INH-21CD manufactured by Koyo Thermo Systems. Then, the temperature was increased to 350°C for 1 hour and heat-treated at 350°C for 1 hour to produce a cured film.

[0330] The storage stability, sensitivity and resolution during patterning, shrinkage of film thickness before and after heat treatment, and adhesion characteristics of the obtained photosensitive polyimide precursor composition were evaluated by the following methods. The results are shown in Table 13.

[0331] [Maintain stability]

[0332] The absolute value of the difference between the optimal exposure time for patterning immediately after preparing the photosensitive polyimide precursor composition and the optimal exposure time for patterning after two weeks at 23°C was calculated and evaluated according to the following criteria.

[0333] ◎: The absolute value of the difference is less than 100 msec

[0334] ○: The absolute value of the difference is greater than 100 msec but less than 200 msec.

[0335] ×: The absolute value of the difference exceeds 200 msec

[0336] [Sensitivity]

[0337] Determine the optimal exposure time (1L / 1S) at which the width of the 50μm line and space pattern (1L / 1S) forms a 1:1 ratio after exposure and development, and evaluate it according to the following criteria. The shorter the optimal exposure time, the higher the sensitivity.

[0338] ◎: The optimal exposure time is below 700 msec.

[0339] ○: The optimal exposure time is between 700msec and 800msec.

[0340] ×: Optimal exposure time exceeds 800 msec

[0341] [Resolution]

[0342] The minimum pattern size at the optimal exposure time after exposure and development is determined and evaluated according to the following criteria. The smaller the minimum pattern size, the higher the resolution.

[0343] ◎: Minimum pattern size is 5μm or less

[0344] ○: Minimum pattern size is between 5μm and 10μm.

[0345] ×: Minimum pattern size exceeds 10μm

[0346] [Shrinkage rate]

[0347] Using a Lambda Ace STM-602 manufactured by Dainippon Screen Mfg, the film thickness (refractive index 1.629) of the developed photosensitive resin film and the film thickness (refractive index 1.773) of the cured film were measured. The shrinkage rate of the film thickness was calculated according to the following formula, and the film was evaluated according to the following criteria.

[0348] Shrinkage rate (%) = (film thickness after development - film thickness after curing) ÷ film thickness after development × 100

[0349] ◎: Shrinkage rate is below 25%

[0350] ○: Shrinkage rate is more than 25% but less than 30%

[0351] ×: Shrinkage rate exceeds 30%

[0352] [Continue with characteristics]

[0353] A photosensitive polyimide precursor composition was coated onto a silicon substrate with a pre-baked film thickness of 10 μm. Pre-baking was performed at 120°C for 2 minutes using a heating plate (Mark-7 coating and developing apparatus manufactured by Tokyo Gosei Corporation). Then, the film was heat-treated at 170°C for 30 minutes in air and then at 350°C for 1 hour to obtain a polyimide film. The polyimide film was subjected to a pressure cooker test (PCT) at 121°C and 2 atmospheres for 400 hours. One hundred 2 mm checkerboard patterns were then fabricated, and a peel test was performed using adhesive tape. The number of peeled checkerboard patterns was counted, and the adhesion properties were evaluated according to the following criteria.

[0354] ○: The number of peeled pieces is less than 30

[0355] ×: The number of peeling particles is 30 or more.

[0356] [Table 13]

[0357]

[0358] Examples 59 to 64 (ink compositions) and Comparative Examples 33 to 36

[0359] Various varnishes (polyimide precursor solutions, polyamide-imide precursor solutions) obtained in Examples 1 to 24 and Comparative Examples 1 to 12 were used directly as ink compositions. The warpage, solvent resistance, plating resistance, flame retardancy, and printability after printing (coating, drying) were evaluated by the following methods and are shown in Table 14.

[0360] [Warping]

[0361] Various varnishes were applied to a copper foil with a length × width × thickness of 50 mm × 50 mm × 13 μm after drying. The foil was then dried in an oven at 400°C for 30 minutes to obtain a laminate with a polyimide resin layer or a polyamide-imide resin layer stacked on the copper foil (substrate). The average warpage at the four corners of the laminate was calculated and evaluated according to the following criteria.

[0362] ◎: The average warpage is less than 1mm.

[0363] ○: The average warpage is more than 1mm but less than 2mm.

[0364] ×: Average warpage exceeds 2mm

[0365] [Soluble Resistance Test]

[0366] The laminates (substrate: copper foil) obtained in the above (warpage) test were immersed in the solvents shown in Table 14 for 5 minutes at room temperature, and the surface (resin layer) condition was observed visually and evaluated according to the following criteria.

[0367] ◎: No change

[0368] ○: Roughness or dissolution is visible on part of the surface.

[0369] ×: Dissolve

[0370] [Coating Resistance]

[0371] The laminates (substrate: copper foil) obtained in the above (warpage) test were subjected to electroless gold plating treatment according to the steps shown below to obtain test specimens. Specifically, the laminates were sequentially immersed in the baths of each step and then dried. The surface condition of the obtained test specimens was visually observed and evaluated according to the following criteria.

[0372] (Electrolytic gold plating process)

[0373] Degreasing (acidic degreasing = acid treatment), water washing, soft etching, water washing, desmear treatment, palladium chloride catalysis, nickel plating (nickel nitrate), gold plating (potassium gold cyanide), water washing, drying.

[0374] (Evaluation Criteria)

[0375] ◎: No change

[0376] ○: Damage is present near the end.

[0377] ×: The surface is covered with granular plating.

[0378] [Flame Retardancy]

[0379] Various varnishes were applied to a polyimide film (Toray DuPont, Kapton 100H, 25μm thickness) to achieve a dried film thickness of 10μm. The film was then dried in an oven at 400°C for 30 minutes to obtain a laminate (substrate: polyimide film) with a polyimide resin layer or a polyamide-imide resin layer stacked on the polyimide film (substrate). The flame retardancy of the resulting laminate was evaluated according to the UL94 Vertical Testing of Thin Materials (VTM) flammability classification as described below.

[0380] ◎:V-0

[0381] ○: V-1

[0382] ×:V-2

[0383] [Printability]

[0384] Various varnishes were applied to a polyimide film (manufactured by Toray DuPont, Kapton 100H, 25μm thick) to print a pattern of lines and gaps with a line width of 500μm and a spacing of 500μm, separated by a 100μm thick stainless steel metal shield. Specifically, printing was performed by placing the metal shield tightly on the polyimide film, spreading various varnishes on the metal shield, filling the openings of the metal shield with liquid using a fluoropolymer squeegee, scraping off excess liquid, and slowly removing the metal shield. After printing, the film was quickly held in a constant temperature and humidity bath at approximately 100% humidity and 50°C for 8 minutes, and then further heated in an oven at 400°C for 30 minutes to obtain a laminate (substrate: polyimide film) with a polyimide resin layer or polyamide-imide resin layer of 15μm to 20μm thickness stacked on the polyimide film (substrate). The printability of the obtained laminate was evaluated according to the following criteria.

[0385] ◎: The pattern has no color bleeding or whitening.

[0386] ○: Although the pattern is recognizable, there is slight bleeding or whitening.

[0387] ×: There is bleeding or whitening of color to an extent that cannot be determined.

[0388] [Table 14]

[0389]

[0390] As shown in Tables 10 to 14, the results of the examples and comparative examples indicate that the polyimide precursors and polyamide-imide precursors synthesized using the resin synthesis solvent (C) containing an amide solvent (A) and a reaction promoter (B), which are embodiments of the present invention, have high molecular weights and can yield precursor solutions (resin varnishes) with low viscosity, high transparency, and high stability. Such resin varnishes are suitable as various adhesive resins and can be used as lubricating coatings (lubricating paints), adhesives, photosensitive resins, and ink compositions.

[0391] [Industry Applicability]

[0392] As explained above, the resin synthesis solvent (C) of the embodiment of the present invention contains an amide solvent (A) and a reaction promoter (B), and can be suitably used to synthesize polyimides, polyamide-imides, polyesterimides, precursors of any of these and / or polyimide copolymers composed of two or more precursors selected from these, as well as polyurethane resins. Resin varnishes such as polyimide varnish, polyamide-imide varnish, and polyurethane resin varnish, manufactured using the resin synthesis solvent described in embodiments of the present invention, are suitable as adhesive resins for various applications. Furthermore, the polyimide films obtained through molding and processing exhibit excellent physical properties and can be suitable as surface protective films or interlayer insulating films for semiconductor components, insulating layers or spacer layers for organic EL (electroluminescence) components, planarization films for thin-film transistor substrates, insulating films for organic transistors, flexible printed circuit boards, flexible device substrates or liquid crystal display substrates, organic EL display substrates, electronic paper substrates, thin-film solar cell substrates, and substrates for light-receiving devices. They are also suitable as adhesives for electrodes in lithium-ion secondary batteries and adhesives for semiconductors. In addition, the polyimide pre-system manufactured using the resin synthesis solvent described in embodiments of the present invention exhibits excellent solubility in soluble polyimides, and is therefore suitable for manufacturing liquid crystal alignment agents.

Claims

1. A solvent (C) for resin synthesis, comprising 10% to 99.9999% by mass of an amide solvent (A) and 0.0001% to 5% by mass of a reaction promoter (B), wherein the reaction promoter (B) is an aliphatic or aromatic tertiary amine compound having one or more tertiary amino groups within its molecule. The solvent (C) for resin synthesis further contains a stabilizer (D) and / or 0.001% to 20% by mass of an ionic liquid, wherein the stabilizer (D) is a compound having active hydrogen in its molecule. The content of the stabilizer (D) relative to the total amount of the reaction promoter (B) is from 10% by mass to 500% by mass.

2. The resin synthesis solvent (C) as described in claim 1, wherein the amide solvent (A) is an alkoxy-N-substituted propionamide of general formula (1); [Chemistry 1] In general formula (1), R1 to R3 independently represent straight-chain alkyl groups having 1 to 22 carbon atoms, branched alkyl groups having 3 to 22 carbon atoms, alkyl ether groups having 2 to 22 carbon atoms, alicyclic hydrocarbon groups having 3 to 22 carbon atoms, and aromatic hydrocarbon groups having 6 to 22 carbon atoms, respectively; R4 represents a hydrogen atom or a methyl group; and may include the following cases: R2 and R3 are each independently hydrogen atoms, but exclude the case where they are both hydrogen atoms; or the case where they form a saturated 5-membered ring to 7-membered ring together with the nitrogen atom carrying said R2 and R3, wherein the 5-membered ring to 7-membered ring may include the case where there is an oxygen atom.

3. The solvent (C) for resin synthesis as described in claim 1 or 2, wherein the reaction promoter (B) is an aliphatic or aromatic tertiary amine compound of general formula (2), wherein the aliphatic or aromatic tertiary amine compound has one or more tertiary amino groups in the molecule, and further has one or more functional groups selected from ether groups, ester groups and amide groups in the molecule; In general formula (2), A, B, and C independently represent straight-chain alkyl groups having 1 to 22 carbon atoms, branched alkyl or alkyl ether groups having 3 to 22 carbon atoms, alkyl ester groups, alkyl amide groups, alicyclic hydrocarbon groups having 3 to 22 carbon atoms, and aromatic hydrocarbon groups having 6 to 22 carbon atoms, respectively; substituents with ether groups represented by general formula (3), substituents with ester groups represented by general formula (4), and substituents with amide groups represented by general formula (5); R5, R7, and R9 in general formulas (3) to (5) represent straight-chain alkylene groups having 1 to 22 carbon atoms, branched alkylene groups or alkylene ether groups having 3 to 22 carbon atoms, alicyclic hydrocarbon groups having 3 to 22 carbon atoms, and aromatic hydrocarbon groups having 6 to 22 carbon atoms, respectively; R6, R8, R 10 and R 11 This refers to straight-chain alkyl groups having 1 to 22 carbon atoms, branched alkyl or alkyl ether groups having 3 to 22 carbon atoms, alkyl ester groups, alkyl amide groups, alicyclic hydrocarbon groups having 3 to 22 carbon atoms, and aromatic hydrocarbon groups having 6 to 22 carbon atoms; additionally, R 10 With R 11 Each can be independently a hydrogen atom, R 10 With R 11 It can also be used with the R carried by 10 and R 11 The nitrogen atoms together form saturated 5-membered to 7-membered rings, which may include cases with oxygen atoms; [Chemistry 2] [Chemistry 3] [Chemistry 4] [Chemistry 5] 。 4. The resin synthesis solvent (C) as described in claim 1 or 2, used for synthesizing polyimide precursors, polyamide-imide precursors, polyester-imide precursors, polyether-imide precursors, polyimide resins, polyamide-imide resins, polyester-imide resins, polyether-imide resins, polyimide copolymer resins composed of any two or more of the various precursors selected from the aforementioned precursors, polyamide resins, polyurethane resins, polyester resins, polyacrylic resins, and fluoropolymers.

5. A method for manufacturing a polyimide precursor, comprising mixing and polymerizing an acid dianhydride with a diamine and / or a diisocyanate using a resin synthesis solvent (C) as described in any one of claims 1 to 4.

6. A method for manufacturing a polyamide-imide precursor, comprising mixing and polymerizing an acid dianhydride with a diamine and / or a diisocyanate using a resin synthesis solvent (C) as described in any one of claims 1 to 4.

7. A method for manufacturing a polyimide by heating and imidizing a polyimide precursor, comprising using a resin synthesis solvent (C) as described in any one of claims 1 to 4 to mix and polymerize an acid dianhydride with a diamine and / or a diisocyanate.

8. A method for manufacturing a polyamide-imide by heating a polyamide-imide precursor, comprising using a resin synthesis solvent (C) as described in any one of claims 1 to 4 to mix and polymerize an acid dianhydride with a diamine and / or a diisocyanate.

9. A method for manufacturing a polyurethane, comprising using a resin synthesis solvent (C) as described in any one of claims 1 to 4 to mix and polymerize a polyol with a diisocyanate.

10. A method for manufacturing a polyurethane dispersion in water, comprising mixing and polymerizing a polyol with a diisocyanate using a resin synthesis solvent (C) as described in any one of claims 1 to 4.

11. A polyurethane dispersion containing a resin synthesis solvent (C) as described in any one of claims 1 to 4.

12. A resin varnish selected from any one of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluororesin varnish, containing a resin synthesis solvent (C) as described in any one of claims 1 to 4.

13. An adhesive resin comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from any one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

14. An ink composition comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

15. A photosensitive resin composition comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

16. An adhesive resin composition comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

17. A resin composition for lubricating coatings, comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, polyurethane resin varnish, polyamide resin varnish, polyacrylic resin varnish, and fluoropolymer varnish.

18. A heat-resistant coating comprising: a resin synthesis solvent (C) as described in any one of claims 1 to 4; and a resin varnish selected from one or more of polyimide varnish, polyamide-imide varnish, polyester-imide varnish, polyether-imide varnish, and fluoropolymer varnish.

19. A method for manufacturing a polyimide film, comprising forming a coating film on a substrate using a coating liquid containing a resin synthesis solvent (C) as described in any one of claims 1 to 4 and a polyimide varnish or a polyimide resin solution, followed by staged heating imidization.

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