Para-type wholly aromatic polyamide solution, and method for producing the same

Abstract

To provide a para-type wholly aromatic polyamide solution by selectively dissolving para-type wholly aromatic polyamide from a compound molding containing a para-type wholly aromatic polyamide molding and a molding comprising another polymer, and to provide the para-type wholly aromatic polyamide molding having high strength, high elastic modulus, high heat resistance, and high dimension stability.SOLUTION: A compound molding is dissolved using an ion liquid containing a cation having no hydrogen adjacent to a polar atom or no π-electron-type hydrogen, and at least one anion selected from the group consisting of carboxylates, carbonates, halides, phosphates, and phosphonates.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solution obtained by dissolving a para-type wholly aromatic polyamide in an ionic liquid, and a method for producing the same. [Background technology]

[0002] Wholly aromatic polyamides (aramids) are polyamides containing an aromatic structure, and include para-type wholly aromatic polyamides (hereinafter sometimes referred to as para-aramids or para-type aramids) and meta-type wholly aromatic polyamides (hereinafter sometimes referred to as meta-aramids or meta-type aramids).

[0003] Examples of para-type wholly aromatic polyamide fibers include polyparaphenylene terephthalamide fibers (DuPont's "Kevlar" (registered trademark), Twaron (registered trademark) manufactured by Teijin), and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (Teijin's "Technora" (registered trademark)). Para-type wholly aromatic polyamide fibers exhibit high heat resistance, high dimensional stability, high strength, and elastic modulus.

[0004] On the other hand, examples of meta-type wholly aromatic polyamide fibers include polymetaphenylene isophthalamide fibers ("Nomex" (registered trademark) manufactured by DuPont, and "Teijinconex" (registered trademark) manufactured by Teijin), and meta-type wholly aromatic polyamide fibers exhibit high elongation and high flame retardancy.

[0005] A known method for forming para-type wholly aromatic polyamide into a fibrous form is to dissolve it in a solvent such as concentrated sulfuric acid, but these solvents also dissolve other polymers such as meta-type wholly aromatic polyamide, so there have been challenges in producing a para-type wholly aromatic polyamide solution from a fibrous structure containing para-type wholly aromatic polyamide and other polymers.

[0006] Furthermore, Patent Documents 1 to 3 disclose a method of dissolving the polymer in a solvent prepared by dissolving an inorganic salt such as lithium chloride or calcium chloride in an aprotic polar organic solvent such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), or hexamethylphosphoramide (HMPA). However, this method also has the problem of dissolving other polymers such as meta-type wholly aromatic polyamides. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 52-46982 [Patent Document 2] Japanese Patent Application Publication No. 04-226533 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-241624 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to solve the problems of the prior art and to provide a para-type wholly aromatic polyamide solution by selectively dissolving a para-type wholly aromatic polyamide from, for example, a composite molding containing a para-type wholly aromatic polyamide molding and a molding made of another polymer, thereby providing a para-type wholly aromatic polyamide molding that maintains high strength, high elastic modulus, high heat resistance, and high dimensional stability. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by using an ionic liquid containing a cation that does not have hydrogen adjacent to a polar atom or hydrogen in a π-electron system, and at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate, and have thus completed the present invention.

[0010] That is, according to the present invention, 1. A para-type wholly aromatic polyamide polymer, an ionic liquid containing a cation having no hydrogen atom adjacent to a polar atom and no hydrogen atom in a π-electron system, and at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate; a para-type wholly aromatic polyamide solution comprising: 2. The para-type wholly aromatic polyamide solution according to the above item 1, wherein the cation contained in the ionic liquid is at least one cation selected from the group consisting of tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, alkylmorpholinium, trialkylsulfonium, and trialkylsulfoquinium. 3. The para-type wholly aromatic polyamide solution according to 1 or 2 above, wherein the content of the para-type wholly aromatic polyamide polymer is 0.01 to 30 mass% based on the total mass of the para-type wholly aromatic polyamide solution. 4. A composite molding containing a para-type wholly aromatic polyamide molding, a method for producing a para-type wholly aromatic polyamide solution, the method comprising dissolving the para-type wholly aromatic polyamide in an ionic liquid containing a cation having no hydrogen atom adjacent to a polar atom and no hydrogen atom in a π-electron system, and at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate, and then removing insoluble matter; and, 5. The method for producing a para-type wholly aromatic polyamide solution according to 4 above, wherein the cation contained in the ionic liquid is at least one cation selected from the group consisting of tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, alkylmorpholinium, trialkylsulfonium, and trialkylsulfoquinium. is provided. [Effects of the Invention]

[0011] According to the present invention, a para-type wholly aromatic polyamide solution can be provided from a composite molding containing, for example, a para-type wholly aromatic polyamide molding and another molding such as a meta-type wholly aromatic polyamide, thereby providing a para-type wholly aromatic polyamide molding that maintains high strength, high elastic modulus, high heat resistance, and high dimensional stability, thereby making it possible to reuse these composite moldings. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below.

[0013] <Para-type wholly aromatic polyamide> The wholly aromatic polyamide of the present invention is a polymer in which one or more types of divalent or higher aromatic groups are directly linked by amide bonds. The aromatic groups have benzene rings bonded to them at the para or meta positions, and these divalent or higher aromatic groups may contain lower alkyl groups such as methyl or ethyl, halogen groups such as methoxy or chlorine, or cyano groups.

[0014] Further, wholly aromatic polyamides are classified into para-type and meta-type, and para-type wholly aromatic polyamides are wholly aromatic polyamides whose main component is a para-type wholly aromatic polyamide consisting of a para-type aromatic dicarboxylic acid chloride component and a para-type aromatic diamine component, where the main component refers to a polyamide in which the total repeating units account for 50 mol% or more.

[0015] The para-type wholly aromatic polyamide also includes a para-type wholly aromatic copolyamide, which is a copolymer. That is, the para-type wholly aromatic copolyamide also includes a para-type wholly aromatic polyamide copolymerized with one or more selected from aromatic dicarboxylic acid chlorides or aromatic diamines in addition to a para-type aromatic dicarboxylic acid chloride component as a first component and a para-type aromatic diamine component as a second component.

[0016] [Raw material for para-type wholly aromatic polyamide] (aromatic carboxylic acid chloride component) Examples of aromatic carboxylic acid chloride components used in the wholly aromatic polyamides include isophthalic acid chloride, terephthalic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, 2,5-furandicarboxylic acid chloride, 3,4-furandicarboxylic acid chloride, pyridine-2,6-dicarboxylic acid chloride, 1,3,5-benzenedicarboxylic acid dichloride, 2,2'-bis(5-chloroformyl-2-furyl)propane, 2-pyrone-4,6-dicarboxylic acid dichloride, etc. Derivatives of these compounds having a substituent on the aromatic ring such as a halogen, an alkoxy group having 1 to 3 carbon atoms, a sulfonic acid group, or a sodium sulfonate group, for example, 3-chloroisophthalic acid chloride, 3-methoxyisophthalic acid chloride, etc., may also be used.

[0017] (aromatic amine component) Examples of aromatic amine components used in the above-mentioned wholly aromatic polyamides include metaphenylenediamine, paraphenylenediamine, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 1,8-diaminonaphthalene, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 2,5-bis(aminomethyl)furan, 1,3,5-benzenetriamine, 2,2'-bis(trifluoromethyl)benzidine, 3,5-diaminobenzoic acid, methyldivanillylamine, and 5-amino-2-(4-aminophenyl)benzimidazole. Furthermore, derivatives having a substituent such as a halogen, an alkoxy group having 1 to 3 carbon atoms, a sulfonic acid group, or a sodium sulfonate group on the aromatic ring, such as 2,4-toluylenediamine, 2,6-toluylenediamine, 2,4-diaminochlorobenzene, or 2,6-diaminochlorobenzene, may also be used.

[0018] <Method of producing para-type wholly aromatic polyamide> The para-type wholly aromatic polyamide can be produced by a conventional method, for example, by reacting an aromatic dicarboxylic acid dichloride (hereinafter also referred to as "acid chloride") component with an aromatic diamine component in an aprotic polar amide organic solvent by solution polymerization or interfacial polymerization.

[0019] (Polymerization solvent) Examples of polymerization solvents used in the production of para-type wholly aromatic polyamides include the aprotic organic solvents described below. These solvents can be used alone or in combination. Organic solvents derived from animals or plants can also be used as polymerization solvents.

[0020] In the case of solution polycondensation, from the viewpoint of the solubility of the para-type wholly aromatic polyamide after polymerization, an aprotic organic polar solvent is preferred, and from the viewpoint of reactivity, an amide organic solvent is more preferred. For example, N-methylformamide, N-methylacetamide, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dipropylformamide, N,N-diisopropylformamide, N,N-dibutylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N,N-dipropylacetamide, N,N-diisopropylacetamide, N,N-dibutylacetamide, N,N-dimethylacetoacetamide, N,N-diethylacetoacetamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N,N-dimethyloctanamide, N,N-dimethyldecanamide, N,N-diethylhexanamide, N,N-diethylbenzamide, N,N-diethyl-3-methylbenzamide, malonamide, pyrrolidine, N-acetyl-2-pyrrolidine, 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), 1-(2-hydroxyethyl)-2-pyrrolidone, 1-propylpyrrolidin-2-one, N-isopropyl N-Alkyl-2-pyrrolidones such as N-isobutyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, and 1-n-octyl-2-pyrrolidone, N-vinylpyrrolidone, 3-bromo-N-methylpyrrolidone, 3-hydroxy-N-methylpyrrolidone, 5-hydroxy-N-methylpyrrolidone, 5-methyl-2-pyrrolidone, and 1,5-dimethyl-2-pyrrolidone. -pyrrolidone, 5-methyl-N-ethylpyrrolidone, 5-methyl-N-hydroxyethylpyrrolidone, 5-methyl-N-propylpyrrolidone, 5-methyl-N-isopropylpyrrolidone, 5-methyl-N-butylpyrrolidone, 5-methyl-N-isobutylpyrrolidone, 5-methyl-N-cyclohexylpyrrolidone, 5-methyl-N-phenylpyrrolidone, 5-ethyl-2-pyrrolidone, 5-propyl-2-pyrrolidone, piperidine, 2,2,6,6- Examples of suitable solvents include tetramethylpiperidine, 2-piperidone, 4-piperidone, N-methyl-2-piperidone, N-methyl-4-piperidone, N-ethyl-4-piperidone, 1,3-dimethyl-2-piperidone, 1,5-dimethyl-2-piperidone, 1,3-dimethyl-4-piperidone, ε-caprolactam, N-methyl-ε-caprolactam, N-vinyl-ε-caprolactam, 1-methylimidazole, and 1,3-dimethyl-2-imidazolidinone. Mixtures of strong organic bases such as DBU and DBN, or aprotic organic solvents such as tetrahydrofuran and 2-methyltetrahydrofuran may also be used.

[0021] [Other polymerization conditions, etc.] The terminals of the resulting wholly aromatic polyamide can also be blocked. When blocking the terminals with a terminal blocking agent, for example, phthalic acid chloride and its substituted derivatives, aniline and its substituted derivatives, etc. can be used as the terminal blocking agent. Furthermore, an aliphatic or aromatic amine can be used in combination to capture the generated acid such as hydrogen chloride.

[0022] The polymer solution obtained by the above-mentioned method for producing a para-type wholly aromatic polyamide can be immersed in a poor solvent such as water and coagulated (wet coagulation), or dried to remove the solvent and coagulate the polymer (dry coagulation), to obtain a molded para-type wholly aromatic polyamide. It is also possible to obtain a powder, fibrid, fibrous, or film-like molded product by wet or dry coagulation. The polymer solution obtained by the above-mentioned method for producing a wholly aromatic polyamide can also be used as is.

[0023] The molecular weight of the polymer used in the present invention is not particularly limited as long as it is sufficient to form molded products such as fibers, films, sheets, coatings, porous films, and particles, but is preferably about 10,000 to 1,000,000. Molecular weights of less than 10,000 are undesirable because the strength of the polymer molded product is low. On the other hand, molecular weights of 1,000,000 or more are undesirable because not only is the solubility in solvents low, but the handleability of the polymer solution is also poor.

[0024] <Composite molding containing para-type wholly aromatic polyamide> The composite molded article containing the para-type wholly aromatic polyamide of the present invention is a molded article containing the above-mentioned molded article made of the para-type wholly aromatic polyamide and a molded article made of another polymer. The shape of the molded article is not particularly limited, and examples thereof include the above-mentioned fibers, films, and sheets, as well as the woven fabric described in JP-A-2008-517181, the pulp described in WO-A-2007 / 075575, and the separator described in WO-A-2019 / 176421.

[0025] Examples of composite moldings containing para-type wholly aromatic polyamides include composite moldings containing a para-type wholly aromatic polyamide molding and at least one molding selected from the group consisting of meta-type wholly aromatic polyamides, polyamides other than wholly aromatic polyamides, polyesters, ultra-high molecular weight polyethylenes, high-density polyethylenes, low-density polyethylenes, polypropylenes, polyvinylidene fluoride, polyamideimides, aromatic polyamideimides, polyimides, cellulose, cellulose acetate, polyacrylonitrile, and polyparaphenylene benzobis oxazole (hereinafter sometimes referred to as PBO).

[0026] Preferably, the composite molding contains a para-type wholly aromatic polyamide and at least one molding selected from the group consisting of a meta-type wholly aromatic polyamide, a polyamide other than a wholly aromatic polyamide, polyester, cellulose, and polyparaphenylene benzobis oxazole.

[0027] More preferably, the composite molded article contains at least one molded article selected from the group consisting of polyparaphenylene terephthalamide, copolyparaphenylene-3.4'-oxydiphenylene terephthalamide, copolyparaphenylene-4.4'-oxydiphenylene terephthalamide, and copolymerized aramid polymers containing metaphenylene terephthalamide units and / or metaphenylene isophthalamide units and paraphenylene terephthalamide units and / or paraphenylene isophthalamide units, and at least one molded article selected from the group consisting of meta-type wholly aromatic polyamides, polyamides other than wholly aromatic polyamides, polyesters, cellulose, and polyparaphenylene benzobis oxazole (hereinafter sometimes referred to as PBO).

[0028] Particularly preferred is a composite molding containing copolyparaphenylene-3,4'-oxydiphenylene terephthalamide and at least one molding selected from the group consisting of meta-type wholly aromatic polyamides, polyamides other than wholly aromatic polyamides, polyesters, cellulose, and polyparaphenylene benzobis oxazole (hereinafter sometimes referred to as PBO).

[0029] The content of the para-type wholly aromatic polyamide molded product in the composite molded product is not particularly limited, but is preferably 10 to 100% by mass. If the content is less than 10% by mass, the effects of the present invention are difficult to obtain, which is not preferable.

[0030] <Ionic liquids (ionic liquids)> Ionic liquids are compounds formed by ionic bonds between an anion derived from an acid and a cation derived from a base. Ionic liquids are also salts with a melting point below 100°C. Examples of types of ionic liquids include aprotic ionic liquids, protic ionic liquids, chelate ionic liquids, metal complex ionic liquids, inorganic ionic liquids, and zwitterionic liquids.

[0031] Examples of cations of ionic liquids include pyrrolium, imidazolium, pyrazolium, pyridinium, pyrimidinium, pyridazinium, pyrazinium, oxazolinium, thiazolium, triazolium, ammonium, cholinium, pyrrolidinium, piperidinium, morpholinium, phosphonium, sulfonium, sulfoquinium, guanidinium, amidinium, protonated amine, protonated amidine, and protonated guanidine.

[0032] The anions in ionic liquids include halides, hydroxides, and alkoxides (ROI) of F, Cl, Br, I, etc. - ), alkyl carboxylates such as acetate and ethanol (RCOO - ), amino acid anions such as glycinate, alaninate, and valinate, alkyl carbonates such as carbonate, methyl carbonate, and ethyl carbonate (ROCOO- ), PF6 - phosphates such as dimethyl phosphate, diethyl phosphate, dibutyl phosphate, etc., alkyl phosphates ((RO)2PO2 - ), alkyl phosphonates such as methyl methylphosphonate, sulfonates such as methanesulfonate, trifluoromethanesulfonate, dodecylbenzenesulfonate, and tosylate (RSO3 - ), hydrogen sulfate, methyl sulfate, etc. sulfate (ROSO3 - ), trifluoromethanesulfonate, bis(fluorosulfonyl)imide, bis(trifluoromethylsulfonyl)imide and other imide anions, dicyanamide, tricyanomethanide, tetrafluoroborate, trifluoro(trifluoromethyl)borate, nitrate, thiocyanate, tetrachloroferrate, hexafluoroanitimonate, and the like can be exemplified.

[0033] In the present invention, it is essential to use, as the cation of the ionic liquid, a cation that does not have hydrogen adjacent to a polar atom or hydrogen in a π-electron system, that is, a cation that has low hydrogen bond donating ability.

[0034] Preferred examples of such cations include tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, alkylmorpholinium, trialkylsulfonium, and trialkylsulfoquinium.

[0035] More preferred examples include tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, and alkylmorpholinium, and particularly preferred examples include tetraalkylammonium having an alkyl group of 1 to 8 carbon atoms, tetraalkylphosphonium having an alkyl group of 1 to 8 carbon atoms, dialkylpyrrolidinium having an alkyl group of 1 to 8 carbon atoms, dialkylpiperidinium having an alkyl group of 1 to 8 carbon atoms, and alkylmorpholinium having an alkyl group of 1 to 8 carbon atoms.

[0036] In the present invention, it is essential to use at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate as the anion of the ionic liquid.

[0037] These anions have high hydrogen bond accepting properties, and specific examples thereof include acetate, propionate, butanoate, bicarbonate, methyl carbonate, ethyl carbonate, propyl carbonate, chloride, dialkyl phosphates having an alkyl group with 1 to 4 carbon atoms, and phosphonates having an alkyl group with 1 to 4 carbon atoms. Particularly preferred examples include acetate, propionate, butanoate, chloride, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, methyl phosphonate, and methylmethyl phosphonate.

[0038] The content ratio of the ionic liquid to the total solvent is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass. If the solvent ratio is less than 50% by mass, the solubility of the para-type wholly aromatic polyamide decreases, which is not preferable.

[0039] Solubility parameters can be used to determine the solubility of a solvent in an ionic liquid, and the Kamlet-Taft solubility parameter is preferably used. The Kamlet-Taft solubility parameter indicates the hydrogen bond donor properties (α), hydrogen bond acceptor properties (β), and dipolarity / polarizability (π*) of the solvent.

[0040] The ionic liquid used in the present invention preferably has a hydrogen bond donating ability α<0.60, a hydrogen bond accepting ability β>0.80, and a polarity / dipolarity π* of 0.40 to 1.20, and more preferably has a hydrogen bond donating ability α<0.40, a hydrogen bond accepting ability β>1.00, and a polarity / dipolarity π* of 0.40 to 1.20.

[0041] <Salt> The above salts include inorganic salts and organic salts. Inorganic salts are salts in which a cation and anion derived from an inorganic compound are ionically bonded. Examples of inorganic salts include combinations of cations such as alkali metal ions, alkaline earth metal ions, rare earth metal ions, and ammonium ions, and anions such as halide ions, sulfate ions, hydrogen sulfate ions, silicate ions, nitrate ions, and phosphate ions. Specific examples include lithium chloride, calcium chloride, potassium nitrate, and potassium sulfate.

[0042] On the other hand, organic salts are those in which either the acid or base is derived from an organic compound, such as lithium acetate, ammonium acetate, potassium propionate, tetramethylammonium chloride, tetrabutylammonium fluoride, tetrabutylammonium bromide, and choline chloride.

[0043] <Solvent> In the present invention, other solvents than the above-mentioned ionic liquids may be used as long as the object of the present invention is not impaired. The solvent used in the present invention is a component other than the polymer that constitutes the polymer solution, such as an aprotic organic solvent, a protic solvent, a eutectic mixture, etc. The solvent ratio in the present invention refers to the mass % of each solvent (aprotic organic solvent, protic solvent, salt, ionic liquid, eutectic mixture) relative to the total solvent in the polymer solution.

[0044] (Aprotic organic solvent) Aprotic organic solvents that can be used in the present invention are solvents that do not have a proton-donating group such as a hydroxyl group and are made of an organic compound, and examples thereof include ethyl carbonate, propyl carbonate, ethyl fluorocarbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, 1,2-butylene carbonate, dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, dipropyl sulfone, sulfolane, dimethyl sulfide, diethyl sulfide, diisopropyl sulfide, dimethyl sulfoxide, diethyl sulfoxide, diethyl ether, propyl ether, isopropyl ether, and dibutylene. ether, diisobutyl ether, cyclopentyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, dioxane, dihydrolevoglucosenone, α-angelicalactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-heptanolactone, γ-octanolactone, γ-nonalactone, γ-decanolactone, δ-valerolactone, δ-hexanolactone, δ-octanolactone, δ-decanolactone, δ-tetradecanolactone, ε-caprolactone, ε-decanolactone dimethyl isosorbide, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, tert-butyl acetate, lauryl acetate, methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, isobutyl acetoacetate, tert-butyl acetoacetate, lauryl acetoacetate, methyl levulinate, ethyl levulinate, propyl levulinate, isopropyl levulinate, Butyl levulinate, isobutyl levulinate, tert-butyl levulinate, dimethyl succinate, diethyl succinate, acetonitrile, succinonitrile, cumene, limonene, methylcyclohexane, N-methylformamide, N-methylacetamide, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dipropylformamide, N,N-diisopropylformamide, N,N-dibutylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N,N-dipropylacetamide, N,N-Diisopropylacetamide, N,N-Dibutylacetamide, N,N-Dimethylacetoacetamide, N,N-Diethylacetoacetamide, 3-Methoxy-N,N-dimethylpropanamide, 3-Butoxy-N,N-dimethylpropanamide, N,N-Dimethyloctanamide, N,N-Dimethyldecanamide, N,N-Diethylhexanamide, N,N-Diethylbenzamide, N,N-Diethyl-3-methylbenzamide, Malonamide, Pyrrolidine, N-Acetyl-2-pyrrolidine, 2-Pyrrolidine N-Alkyl-2-pyrrolidones such as N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), 1-(2-hydroxyethyl)-2-pyrrolidone, 1-propylpyrrolidin-2-one, N-isopropyl-2-pyrrolidone, 1-butylpyrrolidin-2-one, N-isobutyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, and 1-n-octyl-2-pyrrolidone, N-vinylpyrrolidone, 3-bromo-N-methylpyrrolidone, 3- Hydroxy-n-methylpyrrolidone, 5-hydroxy-N-methylpyrrolidone, 5-methyl-2-pyrrolidone, 1,5-dimethyl-2-pyrrolidone, 5-methyl-N-ethylpyrrolidone, 5-methyl-N-hydroxyethylpyrrolidone, 5-methyl-N-propylpyrrolidone, 5-methyl-N-isopropylpyrrolidone, 5-methyl-N-butylpyrrolidone, 5-methyl-N-isobutylpyrrolidone, 5-methyl-N-cyclohexylpyrrolidone, 5-methyl-N-phenylpyrrolidone, 5-ethyl-2-pyrrolidone propyl-2-pyrrolidone, piperidine, 2,2,6,6-tetramethylpiperidine, 2-piperidone, 4-piperidone, N-methyl-2-piperidone, N-methyl-4-piperidone, N-ethyl-4-piperidone, 1,3-dimethyl-2-piperidone, 1,5-dimethyl-2-piperidone, 1,3-dimethyl-4-piperidone, ε-caprolactam, N-methyl-ε-caprolactam, N-vinyl-ε-caprolactam, 1-methylimidazole, 1,3-dimethyl-2-imidazolidinone, N,Examples of suitable amines include N-dimethylpropylene urea, tetramethyl urea, morpholine, 4-methylmorpholine, 4-ethylmorpholine, 4-propylmorpholine, 4-formylmorpholine, 4-acetylmorpholine, 1,4-diacetylpiperazine, N,N-dimethylglycine, N,N-diacetylglycine, pyridine, 2-hydroxypyridine, 2-methylpyridine, 4-methylpyridine, 3,4-dimethylpyridine, 2,6-lutidine, 4-dimethylaminopyridine, 1-methyl-2-pyridone, quinoline, 1-methyl-2-quinoline, and hexamethylphosphoric triamide.

[0045] The content of the aprotic ionic liquid in the entire solvent is preferably 0 to 20% by mass. If it exceeds 20% by mass, other compositions such as meta-type wholly aromatic polyamide tend to dissolve, which is not preferable.

[0046] (protic solvents) The protic solvent that can be used in the present invention is a solvent that has a hydroxyl group and can act as a proton donor, and examples thereof include water, alcohols, amino acids, carboxylic acids, sulfonic acids, and sugars.

[0047] Examples of the solvent include, but are not limited to, water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butyl alcohol, 1-pentanol, 1-hexanol, 2-ethylhexanol, cyclohexanol, 1-octanol, 2-methoxyethanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, glycerin, diacetone alcohol, and glycerol 1,2-carbonate. Examples of suitable saccharides include formic acid, acetic acid, propionic acid, 3-hydroxypropionic acid, butanoic acid, isobutyric acid, 3-hydroxybutanoic acid, caproic acid, lactic acid, succinic acid, levulinic acid, glycolic acid, oxalic acid, methyl lactate, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, 2-ethylhexyl lactate, and diformylxylose; amino acids such as glycine, alanine, valine, leucine, isoleucine, methionine, tyrosine, tryptophan, phenylalanine, asparagine, cytosine, glutamine, serine, threonine, and serine; and maleimide and N-hydroxysuccinimide.

[0048] More preferred examples include water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butyl alcohol, 1-pentanol, 1-hexanol, 2-ethylhexanol, cyclohexanol, 1-octanol, 2-methoxyethanol, ethylene glycol, glycerin, formic acid, acetic acid, propionic acid, 3-hydroxypropionic acid, glycine, alanine, valine, leucine, isoleucine, methionine, tyrosine, tryptophan, phenylalanine, asparagine, cytosine, glutamine, serine, threonine, amino acids such as serine, maleimide, and N-hydroxysuccinimide.

[0049] The solvent of the present invention can be added to the solvent for the purpose of lowering the melting point and reducing the viscosity. The content ratio of the above protic solvent to the total solvent is preferably 0 to 50% by mass. If it exceeds 50% by mass, it is not preferable because the para-type wholly aromatic polyamide becomes difficult to dissolve. These strong organic bases, aprotic organic solvents and protic solvents can be used either individually or as a mixture of two or more.

[0050] In addition, protic solvents, aprotic organic solvents, and strong organic bases derived from plants and animals can also be used in the present invention. The protic solvents and aprotic organic solvents derived from plants and animals in the present invention refer to organic compounds synthesized from plant-derived raw materials (such as sugar / starch biomass and lignocellulosic biomass containing cellulose, hemicellulose, and lignin) and natural products produced by plants and animals or microorganisms. There is no difference in physical properties, such as molecular weight and thermal properties (melting point, boiling point), between organic solvents derived from plants and animals and organic solvents derived from fossils. Therefore, biomass degree is generally used to distinguish between them.

[0051] Biomass degree is the radiocarbon ( 14 This is a value that measures the amount of carbon derived from biomass by measuring the carbon content (C, half-life 5730 years). 14 N 14 C, which is converted into carbon dioxide in the atmosphere. 14 Carbon dioxide is fixed in plants as carbohydrates through photosynthesis, so plants contain 14 On the other hand, fossil-derived petroleum contains the same amount of C. 14 Since carbon is substantially absent, plant-derived carbon can be distinguished from fossil-derived carbon. Generally, ASTM D6866 and the like are known as methods for measuring biomass ratio. Therefore, organic solvents derived from animals and plants according to the present invention can also be distinguished by extracting the organic solvent in the polymer solution and then measuring the biomass ratio.

[0052] Specific examples of the organic solvent of animal or plant origin that can be used in the present invention include, but are not limited to, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, glycerin, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, formic acid, acetic acid, 3-hydroxypropionic acid, butanoic acid, 3-hydroxybutanoic acid, lactic acid, succinic acid, levulinic acid, glycolic acid, acrylic acid, oxalic acid, dimethyl sulfone, dimethyl sulfoxide, diethyl ether, propyl ether, and isopropyl ether. , dibutyl ether, diisobutyl ether, cyclopentyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, dihydrolevoglucosenone, diformylxylose, γ-butyrolactone, γ-valerolactone, δ-valerolactone, δ-decanolactone, ε-caprolactone, dimethyl isosorbide, acetone, cyclopentanone, ethyl acetate, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, 2-ethylhexyl lactate, methyl levulinate, ethyl levulinate, propyl levulinate, propyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, vinylethylene carbonate, 1,2-butylene carbonate, glycerol 1,2-carbonate, acetonitrile, succinonitrile, N,N-Alkyl-2-pyrrolidones such as N-dimethylacetamide (DMAc), 2-pyrrolidone, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), 1-(2-hydroxyethyl)-2-pyrrolidone, 1-propylpyrrolidin-2-one, 1-isopropylpyrrolidin-2-one, 1-butylpyrrolidin-2-one, 1-isobutylpyrrolidin-2-one, 1-pentylpyrrolidin-2-one, 1-isopentylpyrrolidin-2-one, and 1-n-octyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, 5-methyl-2-pyrrolidone, and 1,5-dimethyl Examples of the hydroxybenzoates include 2-pyrrolidone, 5-methyl-N-ethylpyrrolidone, 5-methyl-N-hydroxyethylpyrrolidone, 5-methyl-N-propylpyrrolidone, 5-methyl-N-isopropylpyrrolidone, 5-methyl-N-butylpyrrolidone, 5-methyl-N-isobutylpyrrolidone, 5-methyl-N-cyclohexylpyrrolidone, 5-methyl-N-phenylpyrrolidone, N-methylcaprolactam, 2,6-lutidine, glycine, alanine, valine, leucine, isoleucine, methionine, tyrosine, tryptophan, phenylalanine, asparagine, cytosine, glutamine, serine, threonine, and amino acids such as serine.

[0053] <Para-type wholly aromatic polyamide solution> The para-type wholly aromatic polyamide solution of the present invention can be obtained by dissolving the para-type wholly aromatic polyamide molded product or a composite molded product containing the para-type wholly aromatic polyamide in the ionic liquid, and then removing insoluble matter.

[0054] As mentioned above, the shape of the molded product when dissolving a para-type wholly aromatic polyamide molded product or a composite molded product containing a para-type wholly aromatic polyamide in an ionic liquid can be exemplified as nanofiber, granule, fibrid, fiber, film, porous membrane, etc., but in order to improve solubility, nanofiber, granule, fibrid, or a molded product with a maximum side of 40 mm or less is preferred.

[0055] When dissolving a para-type wholly aromatic polyamide molded product or a composite molded product containing a para-type wholly aromatic polyamide, heating may be performed before or during dissolution to improve solubility. The heating temperature is not particularly limited as long as it is within the range of the melting point, boiling point, or decomposition point of the ionic liquid used, but is preferably -30 to 200°C, and more preferably 25 to 150°C. A heating temperature below -30°C is undesirable because it reduces the cleanability of polymer residues. On the other hand, a heating temperature above 200°C increases operational hazards and makes the product difficult to handle.

[0056] Furthermore, when dissolving a para-type wholly aromatic polyamide molded product or a composite molded product containing a para-type wholly aromatic polyamide, it is preferable to use a mixer to improve solubility and homogenize the para-type wholly aromatic polyamide solution. Known mixers can be used. Examples include a butterfly mixer, a CDM twin-shaft mixer, a BDM twin-shaft mixer, a ribbon mixer, a planetary mixer, a homomixer, and a homogenizer. A shaker or an ultrasonic generator may also be used when dissolving the para-type wholly aromatic polyamide.

[0057] Furthermore, when dissolving a para-type wholly aromatic polyamide molded product or a composite molded product containing a para-type wholly aromatic polyamide, the dissolution may be carried out under a high-pressure gas of 0.10 MPa or more, such as an inert gas (nitrogen, helium, neon, argon, krypton, xenon, or radon), carbon dioxide, hydrogen sulfide, sulfur dioxide, or carbon disulfide.

[0058] A para-type wholly aromatic polyamide solution is obtained by dissolving a para-type wholly aromatic polyamide molded product or a composite molded product containing a para-type wholly aromatic polyamide in an ionic liquid and then filtering off the insoluble matter. Filtration can be performed using a wire mesh filter, nonwoven fabric filter, or the like. The filtration accuracy of the filter is not particularly limited, but is preferably 1 to 500 μm, and more preferably 5 to 100 μm. A filtration accuracy of less than 1 μm is undesirable because the filter tends to clog. On the other hand, a filtration accuracy of 500 μm or more is undesirable because the strength of the composition obtained from the para-type wholly aromatic polyamide solution decreases.

[0059] The concentration of the para-type wholly aromatic polyamide polymer in the para-type wholly aromatic polyamide solution of the present invention is not particularly limited, but is preferably 0.01 to 30% by mass. It is more preferably 1 to 15% by mass. A polymer concentration of less than 0.01% by mass is undesirable because it becomes difficult to mold into a fiber or film. A polymer concentration of more than 30% by mass is also undesirable because it reduces the handleability of the polymer solution or the polymer does not completely dissolve and precipitates.

[0060] Furthermore, the para-type wholly aromatic polyamide solution of the present invention and the molded article made therefrom may contain additives such as flame retardants, colorants, delustering agents, light resistance agents, and conductive agents in order to improve performance.

[0061] <Method for spinning fibers and film molding from a solution of para-type wholly aromatic polyamide> The para-type wholly aromatic polyamide solution of the present invention can also be used for fiber spinning and film molding. The fiber spinning and film molding methods can be carried out according to conventionally known methods, such as dry coagulation and wet coagulation.

[0062] In the case of wet coagulation, the liquid composition of the coagulation liquid must be a poor solvent for the polymer solution. The composition of the coagulation liquid does not necessarily have to be a single one. Although not particularly limited, specific compositions of the coagulation liquid in the present invention include, for example, water, alcohol, carboxylic acid, and a mixed solution containing the solvent of the present invention and at least one of water, alcohol, and carvone. From the viewpoint of solvent recovery efficiency, a mixed solution containing the solvent of the present invention and at least one of water, alcohol, and carvone is preferred.

[0063] The fibrous polymer or film-like polymer formed by coagulation may be washed with water to remove residual solvent, etc. Examples of the solvent include, but are not limited to, water, alcohol, a mixed solution of water and the solvent of the present invention, or a mixed solution of alcohol and the solvent of the present invention. From the viewpoint of solvent recovery efficiency, examples of the solvent include a mixed solution of water and the solvent of the present invention, or a mixed solution of alcohol and the solvent of the present invention.

[0064] After washing with water, the polymer is dried at a temperature of 80° C. or higher. The drying temperature is preferably 80 to 200° C. After drying, the fibrous polymer or film-like polymer may be cut or used as is. The fibrous polymer or film-like polymer after coagulation, or the fibrous polymer or film-like polymer after water washing and drying, can be stretched and heat-treated before use. [Example]

[0065] The present invention will be described in detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to the following examples and comparative examples. In addition, each physical property in the examples was measured by the following methods.

[0066] (1) Solubility of the molded product in solvents 0.2 g of a composite molding containing a para-type wholly aromatic polyamide molding was placed in a solvent containing 10.0 g of ionic liquid, and the solution was stirred at 80°C using a magnetic stirrer for approximately 3 hours. The transparency and uniformity of the solution were then visually evaluated.

[0067] (2) Thickness of the molded product (film) The film thickness was measured according to a method in accordance with JIS C 2151. The formed film was punched out to a size of 100 mm x 100 mm, and measurements were taken at nine equally spaced points, and the average value was calculated to determine the film thickness.

[0068] (3) Heat shrinkage rate of molded product (film) The film was punched out to a size of 10 cm x 10 cm, and marks were made to indicate 8 cm lengths in two directions, parallel to the substrate feeding direction (MD) and perpendicular to the substrate feeding direction (TD), as shown in Figure 2. This sample piece was sandwiched between glass cloths and placed in a dryer set to a temperature of 150°C for 60 minutes, and the thermal shrinkage rate was measured from the dimensional change of the marked 8 cm length before and after heat drying. The thermal shrinkage rate was calculated as the average value in the MD and TD directions.

[0069] (4) Heat resistance of the molded product (film) Thermogravimetric measurements were carried out using a Pyris1 TGA (PerkinElmer) under N2 at a temperature increase rate of 10°C / min from room temperature to 600°C, and the heat resistance was determined at the temperature at which the sample weight decreased by 5%.

[0070] <Comparative Example 1> [Dissolution of polymer] A protective garment containing 93% by mass of meta-type wholly aromatic polyamide fiber (Teijinconex (registered trademark) manufactured by Teijin), 5% by mass of para-type wholly aromatic polyamide fiber (Technora (registered trademark) manufactured by Teijin), and 2% by mass of cellulose fiber (lyocell fiber) was used as the composite molding. 1-Ethyl-3-methylimidazolium acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the composite molding and stirred at 80°C for 3 hours to conduct a solubility test.

[0071] Of the composite moldings, the para-type wholly aromatic polyamide fibers dissolved, but the meta-type wholly aromatic polyamide fibers and cellulose fibers also dissolved, so a para-type wholly aromatic polyamide solution was not obtained.

[0072] <Comparative Example 2> [Dissolution of polymer] Comparative Example 1 was repeated except that the ionic liquid was changed from 1-ethyl-3-methylimidazolium acetate to choline acetate (2-hydroxyethyl(trimethyl)ammonium acetate, manufactured by IoLiTec).

[0073] Of the composite moldings, meta-type wholly aromatic polyamide fibers were partially dissolved, but para-type wholly aromatic polyamide fibers and cellulose fibers did not dissolve, so a para-type wholly aromatic polyamide solution was not obtained.

[0074] Example 1 [Dissolution of polymer] Comparative Example 1 was repeated except that the ionic liquid was changed from 1-ethyl-3-methylimidazolium acetate to tetrabutylammonium acetate (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0075] Among the composite moldings, the para-type wholly aromatic polyamide fibers dissolved, but the meta-type wholly aromatic polyamide fibers and cellulose fibers did not. Therefore, when tetrabutylammonium acetate is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained.

[0076] <Example 2> [Dissolution of polymer] Comparative Example 1 was repeated except that the ionic liquid was changed from 1-ethyl-3-methylimidazolium acetate to tetrabutylammonium chloride (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0077] Among the composite moldings, the para-type wholly aromatic polyamide fibers dissolved, but the meta-type wholly aromatic polyamide fibers and cellulose fibers did not. Therefore, when tetrabutylammonium chloride is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained.

[0078] Example 3 [Dissolution of polymer] Comparative Example 1 was repeated except that the ionic liquid was changed from 1-ethyl-3-methylimidazolium acetate to tetrabutylammonium benzoate (manufactured by Sigma-Aldrich).

[0079] Among the composite moldings, the para-type wholly aromatic polyamide fibers dissolved, but the meta-type wholly aromatic polyamide fibers and cellulose fibers did not. Therefore, when tetrabutylammonium benzoate is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained.

[0080] Example 4 [Dissolution of polymer] The same procedure as in Example 1 was carried out, except that the composite molding was changed to a protective garment containing 70 mass% of para-type wholly aromatic polyamide fiber (Teijin's "Technora" (registered trademark)) and 30 mass% of polyethylene terephthalate fiber (Teijin's "Tetoron" (registered trademark)).

[0081] In the composite molding, the para-type wholly aromatic polyamide fiber dissolved, but the polyethylene terephthalate fiber did not. Therefore, when tetrabutylammonium acetate is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained.

[0082] <Example 5> [Dissolution of polymer] The same procedure as in Example 1 was carried out, except that the composite molding was changed to a protective garment containing 98 mass% of para-type wholly aromatic polyamide fiber (Teijin's "Technora" (registered trademark)) and 2 mass% of polyparaphenylene benzobis oxazole fiber (PBO fiber).

[0083] Among the composite moldings, the para-type wholly aromatic polyamide fiber dissolved, but the polyparaphenylene benzobis oxazole fiber (PBO fiber) did not. Therefore, when tetrabutylammonium acetate is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained. The results of Comparative Examples 1 and 2 and Examples 1 to 5 are shown in Table 1.

[0084] [Table 1]

[0085] <Reference example 1> [Polymerization and isolation of meta-type wholly aromatic polyamides] Meta-phenylenediamine and isophthalic acid chloride were polymerized by a known method (interfacial polymerization, JP-B 47-10863) to obtain a meta-type wholly aromatic polyamide (polymetaphenylene isophthalamide) powder.

[0086] [Molding (film) of meta-type wholly aromatic polyamide] The meta-type wholly aromatic polyamide powder was dissolved in 1-methyl-2-pyrrolidone (NMP) to obtain a meta-type wholly aromatic polyamide solution with a polymer concentration of 6.0% by mass. The meta-type wholly aromatic polyamide solution was molded into a film, dried in a steam dryer at 120°C for 2 hours, and then solidified and washed with distilled water to obtain a film-like molded product. The film-like molded product had a film thickness of 10.1 μm and a heat resistance of 427°C.

[0087] <Reference example 2> [Polymerization of para-type wholly aromatic polyamides] 94.0 g of N-methyl-2-pyrrolidone (NMP) with a moisture content of less than 100 ppm, 0.540 g of paraphenylenediamine, and 1.001 g of 3,4'-diaminodiphenyl ether were placed in a reaction vessel at room temperature and dissolved under a nitrogen atmosphere. 2.030 g of terephthaloyl chloride was then added with stirring. Polymerization was then carried out at 60°C, yielding a clear, viscous polymer solution. Next, 3.293 g of a 22.5% NMP slurry of calcium hydroxide was added to neutralize the polymerization, yielding a solution of para-type wholly aromatic polyamide (copolyparaphenylene-3,4'-oxydiphenylene-terephthalamide).

[0088] [Molding (film) of para-type wholly aromatic polyamide solution] A 3.0% polymer solution of copolyparaphenylene·3,4'-oxydiphenylene·terephthalamide was cast into a film, dried in a steam dryer at 120°C for 2 hours, and then solidified and washed with distilled water to obtain a film-like molded product. The film-like molded product had a film thickness of 10.1 μm and a heat resistance of 464°C.

[0089] <Comparative Example 3> A polymer solution containing a known para-type wholly aromatic polyamide and a known meta-type wholly aromatic polyamide (para-type wholly aromatic polyamide content: 40% by mass; JP2019 / 176421A) was molded by a known method to obtain a polymer molded product A containing a film-like para-type wholly aromatic polyamide.

[0090] The obtained film-like molding A was cut to a maximum side of 3 mm or less, and 10.0 g of 1-ethyl-3-methylimidazolium acetate was added to 1.00 g of the cut film-like molding, followed by stirring at 80°C for 3 hours and then filtering through a wire mesh filter with a filtration accuracy of 77 μm to obtain a polymer solution.

[0091] The undissolved matter collected on the wire mesh filter was washed with NMP and water, then dried and weighed. The undissolved matter was 0.08 g, and the polymer concentration calculated from the mass of the added polymer molded product and the mass of the undissolved matter was 8.4 mass%. The filtered polymer solution was molded into a film by a known method. The obtained film-shaped molded product B had a film thickness of 10.9 μm and a heat resistance of 435° C.

[0092] Of the polymer molding A containing the para-type wholly aromatic polyamide and the meta-type wholly aromatic polyamide, both the para-type wholly aromatic polyamide and the meta-type wholly aromatic polyamide dissolved, so a para-type wholly aromatic polyamide solution was not obtained. Therefore, the film-like molded product B obtained from the above solution merely had heat resistance equivalent to that of the meta-type wholly aromatic polyamide molded product of Reference Example 1.

[0093] Example 6 A polymer solution was obtained in the same manner as in Comparative Example 3, except that 10.0 g of tetrabutylammonium acetate was added to 1.00 g of the cut film-like molded product A.

[0094] The undissolved matter collected on the wire mesh filter was washed with NMP and water, then dried and weighed. The undissolved matter was 0.65 g, and the polymer concentration calculated from the mass of the added polymer molded product and the mass of the undissolved matter was 2.5 mass%. The filtered polymer solution was molded into a film by a known method. The obtained film-shaped molded product C had a film thickness of 9.8 μm and a heat resistance of 463°C.

[0095] In this example, of the film-like molded product A containing a para-type wholly aromatic polyamide and a meta-type wholly aromatic polyamide, the para-type wholly aromatic polyamide dissolved, but the meta-type wholly aromatic polyamide did not. Therefore, when tetrabutylammonium acetate is used as the ionic liquid, the para-type wholly aromatic polyamide can be selectively dissolved, and a para-type wholly aromatic polyamide solution can be obtained.

[0096] Furthermore, the film-like molded product C obtained from the above solution has physical properties equivalent to those of the para-type wholly aromatic polyamide molded product of Reference Example 2. The results of Comparative Example 3 and Example 6 are shown in Table 2.

[0097] [Table 2] [Industrial Applicability]

[0098] According to the present invention, a para-type wholly aromatic polyamide solution can be provided from a composition containing a para-type wholly aromatic polyamide and another polymer such as a meta-type wholly aromatic polyamide, and a para-type wholly aromatic polyamide composition that maintains high strength, high elastic modulus, and high heat resistance can be provided. In addition, the composition containing the para-type wholly aromatic polyamide and another polymer such as a meta-type wholly aromatic polyamide can be reused.

Claims

1. a para-type wholly aromatic polyamide polymer; an ionic liquid containing a cation having no hydrogen atom adjacent to a polar atom and no hydrogen atom in a π-electron system, and at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate; A para-type wholly aromatic polyamide solution comprising:

2. The para-type wholly aromatic polyamide solution according to claim 1, wherein the cation contained in the ionic liquid is at least one cation selected from the group consisting of tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, alkylmorpholinium, trialkylsulfonium, and trialkylsulfoquinium.

3. 3. The para-type wholly aromatic polyamide solution according to claim 1, wherein the content of the para-type wholly aromatic polyamide polymer is 0.01 to 30% by mass based on the total mass of the para-type wholly aromatic polyamide solution.

4. A composite molding containing a para-type wholly aromatic polyamide molding, A method for producing a para-type wholly aromatic polyamide solution, comprising dissolving the polyamide in an ionic liquid containing a cation that does not have a hydrogen atom adjacent to a polar atom or a hydrogen atom in a π-electron system, and at least one anion selected from the group consisting of carboxylate, carbonate, halide, phosphate, and phosphonate, and then removing insoluble matter.

5. The method for producing a para-type wholly aromatic polyamide solution according to claim 4, wherein the cation contained in the ionic liquid is at least one cation selected from the group consisting of tetraalkylammonium, tetraalkylphosphonium, dialkylpyrrolidinium, dialkylpiperidinium, alkylmorpholinium, trialkylsulfonium, and trialkylsulfoquinium.

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