Resin composition, nonwoven fabric and textile product using the same, separator for electric storage element, secondary battery and electric double layer capacitor

Abstract

The present invention addresses the problem of providing a resin composition suitable for spinning, especially electrospinning, and of providing heat-resistant nonwoven fabric having excellent strength and a method for producing the heat-resistant nonwoven fabric. The resin composition comprises (a) at least one heat-resistant resin or a precursor thereof, the resin being selected from the group consisting of nitrogen-atom-containing heat-resistant resins and heat-resistant resins each having a main chain containing a group selected from the group consisting of ether, ketone, sulfone, and sulfide groups, (b) a solvent, and (c) a surfactant having a fluoroalkyl group. The resin composition is used to form nonwoven fabric by an electrospinning method.

Description

[Technical Field]

[0001] The present invention relates to a resin composition for forming a nonwoven fabric by electrospinning, a nonwoven fabric, and a textile product, a separator for an electric storage element, a secondary battery, and an electric double layer capacitor using the nonwoven fabric. [Background technology]

[0002] In recent years, electronic devices have required lower dielectric constants, which has led to a demand for porous, heat-resistant materials. Heat-resistant nonwoven fabrics that can withstand soldering processes are a promising candidate for the substrate of such materials. Furthermore, by metal-plating heat-resistant nonwoven fabrics, they can be used in a variety of applications, including lightweight and excellent electromagnetic wave shielding materials, heat-resistant bag filters for removing dust from combustion gases emitted from factories, gas and water separation membranes, and separators for lithium-ion batteries and electric double-layer capacitors. For these applications, metal-plated heat-resistant nonwoven fabrics have attracted attention as materials with excellent ion permeability, high mechanical strength, and heat resistance.

[0003] Furthermore, in aircraft applications, there is an increasing demand for heat-insulating and sound-absorbing materials with many voids that are highly reliable in high-temperature and low-temperature environments.

[0004] As a method for obtaining the above-described nonwoven fabric, Patent Document 1 discloses a polyimide composition having a specific structure suitable for electrospinning and a method for producing a nonwoven fabric using the same, which is used as a bag filter or a combustion exhaust gas filter used at high temperatures.

[0005] Patent Document 2 discloses that a polyimide solution is ejected from a nozzle and then exposed to a high-speed air current that crosses the solution to obtain polyimide fibers, which are then used in applications such as heat-resistant bag filters, heat-insulating sound-absorbing materials, and heat-resistant clothing.

[0006] Patent Document 3 discloses a separator for lithium-ion secondary batteries that uses a resin solution obtained by reacting polyamic acid with an alkoxysilane partial condensate containing an epoxy group. Plating adhesion is improved by silane-modifying the polyamic acid. Furthermore, during spinning, an airflow heated to 50 to 350°C is applied to the solution discharged from the spinneret, promoting imidization and sol-gel reactions while collecting the thread.

[0007] Patent Document 4 discloses polyamide, polyimide, and polyamideimide resins in which alkyl groups and fluoroalkyl groups are bonded to the polymer terminals, as well as nonwoven fabrics and separators using solutions of these resins. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-132611 [Patent Document 2] International Publication No. 2009 / 054349 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-251287 [Patent Document 4] International Publication No. 2019 / 009037 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the compositions disclosed in these patent documents suffer from poor spinning stability. For example, they can develop "beads," which are nodular defects where the fiber diameter suddenly increases, or the charge repulsion during spinning can become unstable, causing the fiber to lose its shape and deposit on the substrate as round droplets. These problems can lead to a decrease in the strength of the nonwoven fabric.

[0010] An object of the present invention is to provide a resin composition suitable for spinning, particularly electrospinning, and a heat-resistant nonwoven fabric having excellent strength and a method for producing the same. [Means for solving the problem]

[0011] The present invention provides a resin composition for forming a nonwoven fabric by electrospinning, comprising: (a) at least one heat-resistant resin or a precursor thereof selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain; (b) a solvent; and (c) a surfactant having a fluoroalkyl group. (c) a resin composition in which the surfactant having a fluoroalkyl group has at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen. is.

[0012] The present invention also provides a nonwoven fabric comprising: (a) at least one heat-resistant resin or a precursor thereof selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain; and (c) a surfactant having a fluoroalkyl group. (c) a nonwoven fabric in which the surfactant having a fluoroalkyl group has at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen. is. [Effects of the Invention]

[0013] According to the present invention, the generation of beads during spinning can be suppressed, and threads with a stable diameter can be obtained. In particular, in electrospinning, the splitting of the resin liquid due to charge repulsion during spinning is not hindered, and a nonwoven fabric without the accumulation of droplets can be obtained. Furthermore, according to the present invention, a heat-resistant nonwoven fabric with excellent strength can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the resin composition, nonwoven fabric, nonwoven fabric manufacturing method, textile product, separator, secondary battery, and electric double layer capacitor according to the present invention will be described in detail below. However, the present invention is not limited to these embodiments.

[0015] <Resin composition> The resin composition according to an embodiment of the present invention comprises, as the resin of component (a), i) Heat-resistant resin containing nitrogen atoms ii) a heat-resistant resin having, in its main chain, a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group; iii) a precursor of the heat-resistant resin of i) above; iv) a precursor of the heat-resistant resin of ii) above; One or more of these may be used.

[0016] The resin composition of the present invention further contains at least (b) a solvent and (c) a surfactant having a fluoroalkyl group, in addition to the resin component (a).

[0017] Here, the term "heat-resistant resin" as used herein refers to a resin whose 5% weight loss temperature is 200°C or higher. Also, the term "heat-resistant resin precursor" refers to a substance that provides a heat-resistant resin by being subjected to thermal or chemical treatment such as crosslinking, thermal ring closure, or chemical ring closure, without relying on an addition reaction.

[0018] The 5% weight loss temperature is the temperature at which the weight W2 of the resin during heating becomes W2 / W1=0.95 when the resin is heated to 150°C at a heating rate of 10°C / min in a nitrogen stream to remove adsorbed water, then cooled to room temperature and the weight W1 is measured, and the resin is then heated again at a heating rate of 10°C / min.

[0019] (a-1) Heat-resistant resin containing nitrogen atoms A heat-resistant resin containing a nitrogen atom refers to a resin that has a nitrogen atom-containing group, such as an amide group or a urea group, or a nitrogen atom-containing heterocycle, such as an imide ring or an oxazole ring, in the repeating structure of the polymer, and has a 5% weight loss temperature of 200°C or higher.

[0020] Examples of heat-resistant resins containing nitrogen atoms include polyimide, polyamide, polyurea, polyamideimide, and polyazoles (polybenzimidazole, polybenzoxazole, and polybenzothiazole).

[0021] More preferably, the heat-resistant resin containing a nitrogen atom is specifically a resin having a structure represented by at least one selected from the following general formulas (1) to (5).

[0022] [ka]

[0023] In general formula (1), R 1 represents a divalent group having 2 to 50 carbon atoms. 2 represents a tetravalent group having 4 to 50 carbon atoms. m1 represents an integer of 1 to 10,000.

[0024] [ka]

[0025] In general formula (2), R 3 represents a divalent group having 2 to 50 carbon atoms. 4 represents a trivalent group having 4 to 50 carbon atoms. m2 represents an integer of 1 to 10,000.

[0026] [ka]

[0027] In general formula (3), R 5 represents a divalent group having 2 to 50 carbon atoms. 6 represents a divalent group having 2 to 50 carbon atoms. m3 represents an integer of 1 to 10,000.

[0028] [ka]

[0029] In general formula (4), R 7 represents a divalent group having 2 to 50 carbon atoms. 8 represents a divalent group having 2 to 50 carbon atoms. m4 represents an integer of 1 to 10,000.

[0030] [ka]

[0031] In general formula (5), R 9 represents a divalent group having 2 to 50 carbon atoms. 10 represents a tetravalent group having 4 to 50 carbon atoms. X represents a divalent group selected from -O-, -S-, -NH-, and -C(=O)O-. m5 represents an integer from 1 to 10,000.

[0032] In addition, R 1 ~R 10 is typically a residue of an aliphatic hydrocarbon, an aromatic hydrocarbon, or a nitrogen-containing aromatic hydrocarbon, and also includes those in which these are bonded together via a linking group such as a single bond, an ether bond, a thioether bond, an ester bond, a ketone bond, or a sulfone bond, and those in which some of the hydrogen atoms have been substituted with a monovalent functional group such as an alkyl group, a halogenated alkyl group, an oxyalkyl group, an oxyaryl group, a nitro group, a cyano group, or a halogen.

[0033] The structure represented by general formula (1) is a structural unit of polyimide. 1represents a diamine residue. Amine components that provide the diamine residue include carboxyl group-containing diamines such as 3,5-diaminobenzoic acid and 3-carboxy-4,4'-diaminodiphenyl ether, sulfonic acid-containing diamines such as 3-sulfonic acid-4,4'-diaminodiphenyl ether, bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(3-amino-4-hydroxyphenyl)sulfone, bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)methane, bis(3-amino-4-hydroxyphenyl) bis(4-amino-3-hydroxyphenyl) ether, bis(3-amino-4-hydroxy)biphenyl, bis(3-amino-4-hydroxyphenyl)fluorene, bis(4-amino-3-hydroxyphenyl)hexafluoropropane, bis(4-amino-3-hydroxyphenyl)sulfone, bis(4-amino-3-hydroxyphenyl)propane, bis(4-amino-3-hydroxyphenyl)methane, bis(4-amino-3-hydroxyphenyl) ether, bis(4-amino-3-hydroxy)biphenyl, bis(4-amino-3-hydroxyphenyl)fluorene, etc. Any hydroxyl-containing diamine or amine in which the hydroxyl group is replaced by a thiol group, an amino group, or a carboxyl group, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy)benzene, m-phenylenediamine p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis(4-aminophenoxyphenyl)sulfone, bis(3-aminophenoxyphenyl)sulfone, 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'-dimethyl-4,Examples of suitable amines include, but are not limited to, 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, compounds in which some of the hydrogen atoms in the aromatic rings of these amines have been substituted with alkyl groups or halogen atoms, and aliphatic diamines such as cyclohexyldiamine and methylenebiscyclohexylamine. These amines can be used alone or in combination of two or more.

[0034] In general formula (1), R 2represents a tetracarboxylic acid residue. Acid components that give rise to tetracarboxylic acid residues include pyromellitic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 2,2',3,3'-benzophenonetetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 2,2-bis(2,3-dicarboxyphenyl)hexafluoropropane, 1,1-bis(3,4-dicarboxyphenyl)ethane, 1,1-bis(2,3-dicarboxyphenyl)ethane, bis(3,4-dicarboxyphenyl)methane, bis(2,3-dicarboxyphenyl)methane, and bis(3,4-dicarboxyphenyl). Examples of suitable tetracarboxylic acids include, but are not limited to, sulfones, bis(3,4-dicarboxyphenyl)ether, aromatic tetracarboxylic acids such as 1,2,5,6-naphthalenetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,3,5,6-pyridinetetracarboxylic acid, and 3,4,9,10-perylenetetracarboxylic acid, and aliphatic tetracarboxylic acids such as cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, cyclohexanetetracarboxylic acid, bicyclo[2.2.1]heptanetetracarboxylic acid, bicyclo[3.3.1]tetracarboxylic acid, bicyclo[3.1.1]hept-2-enetetracarboxylic acid, bicyclo[2.2.2]octanetetracarboxylic acid, and adamantanetetracarboxylic acid. These acids can be used alone or in combination.

[0035] The structure represented by general formula (2) is a structural unit of polyamideimide. The structure represented by general formula (3) is a structural unit of polyamide. The structure represented by general formula (4) is a structural unit of polyurea. The structure represented by general formula (5) is a structural unit of polyazole.

[0036] In general formula (2) and general formula (4), R 3 , R 7 represents a diamine residue. The amine component that gives the diamine residue is R1 The same can be mentioned as in the description of

[0037] In general formula (2), R 4 represents a tricarboxylic acid residue. Examples of acid components that provide the tricarboxylic acid residue include, but are not limited to, trimellitic acid, trimesic acid, diphenyl ether tricarboxylic acid, and biphenyl tricarboxylic acid. These acids can be used alone or in combination of two or more.

[0038] In general formula (4), R 8 represents a diisocyanate residue, and represents a divalent group having 2 to 50 carbon atoms. The diisocyanate component that gives the diisocyanate residue is R 1 Examples of the diisocyanate include a structure in which the amino group of the diamine in the description of (1) is replaced with an isocyanate group. These diisocyanates can be used alone or in combination of two or more.

[0039] In general formula (5), R 10 represents a diamine residue in which a group represented by XH is bonded to the ortho position relative to the amino group. X represents a unit selected from -O-, -S-, -NH-, and -C(=O)O-. By arranging it in the ortho position, a polyazole can be obtained by dehydration ring closure. -R 20Diamine components that give diamine residues with the structure (XH)2- include bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(3-amino-4-hydroxyphenyl)sulfone, bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)methylene, bis(3-amino-4-hydroxyphenyl)ether, bis(3-amino-4-hydroxy)biphenyl, bis(3-amino-4-hydroxyphenyl)fluorene, and bis(4-amino-3-hydroxyphenyl)hexafluoropropane. Examples of suitable amines include, but are not limited to, hydroxyl group-containing diamines such as fluoropropane, bis(4-amino-3-hydroxyphenyl)sulfone, bis(4-amino-3-hydroxyphenyl)propane, bis(4-amino-3-hydroxyphenyl)methylene, bis(4-amino-3-hydroxyphenyl)ether, bis(4-amino-3-hydroxy)biphenyl, and bis(4-amino-3-hydroxyphenyl)fluorene, as well as amines in which the hydroxyl groups are replaced with thiol groups, amino groups, or carboxyl groups. These amines can be used alone or in combination of two or more.

[0040] In general formula (3), R 5 represents a diamine residue. The amine component that gives the diamine residue is R 1 The same things can be mentioned as in the explanation of R 10 This does not include diamine residues in which the group represented by XH is bonded at the ortho position relative to the amino group, as shown below.

[0041] In general formula (3) and general formula (5), R 6 , R 9represents a dicarboxylic acid residue. Examples of acid components that provide the dicarboxylic acid residue include, but are not limited to, terephthalic acid, isophthalic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl thioether dicarboxylic acid, biphenyl dicarboxylic acid, 2,2'-bis(4-carboxy)hexafluoropropane, 2,2'-bis(4-carboxy)propane, and diphenyl ketone dicarboxylic acid. These acids can be used alone or in combination of two or more.

[0042] From the viewpoints of minimizing deterioration of the resin composition when stored at room temperature and minimizing the effect on spinning properties even when stored at room temperature for a long period of time, the most preferred heat-resistant resin containing nitrogen atoms is a resin having a polyamideimide structure represented by general formula (2). Having both an amide structure and an imide structure improves compatibility with (b) solvents and (c) surfactants having a fluoroalkyl group, and has the advantage of suppressing bead formation even after long-term storage of the composition at room temperature.

[0043] In a more preferred embodiment, R 3 has a residue of 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfide, or 4,4'-diaminodiphenyl sulfide, or a structure represented by the following general formula (6) or general formula (7).

[0044] Since fine fibers can be obtained during spinning, R in general formula (1) 1 , R in general formula (2) 3 , R in general formula (3) 5 , R in general formula (3) 6 , R in general formula (4) 7 , R in general formula (4) 8 and R in general formula (5) 9It is preferable that 30 mol % or more, more preferably 50 mol % or more of them have a structure represented by the following general formula (6) or general formula (7), and typically, a structure represented by general formula (6) or general formula (7).

[0045] [ka]

[0046] In general formula (6), R 11 represents a monovalent group having 1 to 6 carbon atoms, and is located in the ortho position relative to the polymer main chain. n1 represents an integer of 1 to 4, and is preferably 1 or 2.

[0047] [ka]

[0048] In general formula (7), R 12 and R 13 each independently represents a monovalent group having 1 to 6 carbon atoms and is located in the ortho position relative to the polymer main chain. n2 and n3 each independently represent an integer of 1 to 4, preferably 1 or 2. X2 represents at least one selected from a single bond, -O-, -S-, -CH2-, -C(CH3)2-, and -C(CF3)2-.

[0049] R 11 ~R 13 Preferred examples of include, but are not limited to, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a cyclohexyl group. More preferred are a methyl group and an ethyl group.

[0050] More preferred specific examples of the structure represented by general formula (6) or (7) include the structures shown below.

[0051] [ka]

[0052] [ka]

[0053] Resins having structures represented by these general formulas (1) to (5) do not require high-temperature heating for dehydration and cyclization, which prevents yarn shrinkage due to dehydration and cyclization, and allows for the production of nonwoven fabrics with higher shape stability.

[0054] Resins having structures represented by general formulas (1) to (5) can be obtained by reacting a diamine, a diisocyanate that yields a similar diamine residue, or a trimethylsilylated diamine that yields a similar diamine residue with a tetracarboxylic acid derivative, a tricarboxylic acid derivative, a dicarboxylic acid derivative, or a diisocyanate in a known dipolar solvent such as N-methylpyrrolidone or dimethylacetamide. The reaction temperature is appropriately selected from -5 to 80°C for resins having a structure represented by general formula (3) or (4). Furthermore, the reaction temperature is appropriately selected from -5 to 250°C for resins having a structure represented by general formula (1), (2), or (5).

[0055] The organic solvent used as the reaction solvent is not particularly limited as long as it dissolves the resin, but aprotic polar solvents are generally preferred, such as diphenyl sulfone, dimethyl sulfoxide, sulfolane, dimethyl sulfone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylisobutyramide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-methyl-2-pyrrolidone, diethyl sulfone, diethyl sulfoxide, 1,4-dimethylbendazolidinone, hexamethyltriamide, and 1,3-dimethylimidazolidinone. In addition, ketone solvents with a high boiling point such as cyclohexanone, ether solvents such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol methyl ethyl ether, and dipropylene glycol diethyl ether, and aromatic hydrocarbon solvents such as toluene and xylene, and ester solvents such as propylene glycol monomethyl ether acetate and methyl-methoxybutanol acetate can also be added to these.

[0056] The amount of solvent used in polycondensation is preferably 50 parts by weight or more, more preferably 100 parts by weight or more, based on 100 parts by weight of the total monomers. By using a solvent amount of 50 parts by weight or more based on the total monomer weight, operations such as stirring are facilitated, and the polycondensation reaction tends to proceed smoothly. On the other hand, a solvent amount of 500 parts by weight or less is preferred, more preferably 250 parts by weight or less. By using a solvent amount of 500 parts by weight or less, the monomer concentration in the solvent increases and the polymerization rate improves, making it easy to obtain a high molecular weight polymer with a weight average molecular weight of 10,000 or more.

[0057] The weight-average molecular weight of the resin in the present invention is preferably in the range of 5,000 to 300,000, and particularly preferably in the range of 10,000 to 200,000. The weight-average molecular weight in the present invention refers to a value calculated using a standard polystyrene calibration curve after measuring the molecular weight of the resin by gel permeation chromatography (GPC) using a mixed solvent of NMP / H3PO4 to which 1 M lithium chloride has been added.

[0058] (a-2) Precursor of heat-resistant resin containing nitrogen atoms Preferable examples of the nitrogen atom-containing heat-resistant resin precursor include a polyimide precursor, a polyamideimide precursor, a polyazole precursor, etc. When using these precursors, a heat treatment at 120 to 500°C is required after spinning to dehydrate and close the ring.

[0059] Specifically, it is a resin having a structure represented by the following general formulas (8) to (10).

[0060] [ka]

[0061] In general formula (8), R 14 represents a divalent group having 2 to 50 carbon atoms. 15 represents a tetravalent group having 4 to 50 carbon atoms. 16 OH, OR 17 and O - R 18+ R represents at least one of the following: 17 represents a monovalent group having 1 to 10 carbon atoms. 18+ represents a monovalent metal cation or an ammonium ion, and m6 represents an integer of 1 to 10,000.

[0062] [ka]

[0063] In general formula (9), R 19 represents a divalent group having 2 to 50 carbon atoms.20 represents a trivalent group having 4 to 50 carbon atoms. 21 OH, OR 22 and O - R 23+ R represents at least one of the following: 22 represents a monovalent group having 1 to 10 carbon atoms. 23+ represents a monovalent metal cation or an ammonium ion, and m7 represents an integer of 1 to 10,000.

[0064] [ka]

[0065] In general formula (10), R 24 represents a divalent group having 2 to 50 carbon atoms. 25 represents a trivalent group having 4 to 50 carbon atoms. m8 represents an integer of 1 to 10,000.

[0066] In addition, R 14 , R 15 , R 17 , R 19 , R 20 , R 22 , R 24 and R 25 are typically residues of aliphatic hydrocarbons, aromatic hydrocarbons, and nitrogen-containing aromatic hydrocarbons, and also include those in which these are bonded together via a linking group such as a single bond, an ether bond, a thioether bond, an ester bond, a ketone bond, or a sulfone bond, and those in which some of the hydrogen atoms have been substituted with a monovalent functional group such as an alkyl group, a halogenated alkyl group, an oxyalkyl group, an oxyaryl group, a nitro group, a cyano group, or a halogen.

[0067] The structure represented by general formula (8) is a structural unit of a polyimide precursor. The structure represented by general formula (9) is a structural unit of a polyamideimide precursor. The structure represented by general formula (10) is a structural unit of a polyazole precursor.

[0068] In general formula (8) and general formula (9), R 14 , R 19represents a diamine residue. The amine component that gives the diamine residue is R 1 The same can be mentioned as in the description of

[0069] In general formula (10), R 24 represents a diamine residue. The amine component that gives the diamine residue is R 10 The same can be mentioned as in the description of

[0070] In general formula (8), R 15 represents a tetracarboxylic acid residue. The acid component that gives the tetracarboxylic acid residue is R 2 The same can be mentioned as in the description of

[0071] In general formula (9), R 20 represents a tricarboxylic acid residue. The acid component that gives the tricarboxylic acid residue is R 4 The same can be mentioned as in the description of

[0072] In general formula (10), R 25 represents a dicarboxylic acid residue. The acid component that gives the dicarboxylic acid residue is R 9 The same can be mentioned as in the description of

[0073] In general formula (8) and general formula (9), R 17 , R 22 From the viewpoint of suppressing cracking of the yarn due to shrinkage during dehydration ring closure, preferred are, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, cyclohexyl, etc. These groups can be used alone or in combination of two or more.

[0074] In general formula (8) and general formula (9), R 18+ , R 23+Specific examples of the metal cations include, but are not limited to, sodium ions, potassium ions, and lithium ions. Specific examples of ammonium ions include, but are not limited to, hydrogenated trialkylamines such as trimethylamine, triethylamine, and triisopropanolamine; hydrogenated heterocycle-containing monoamines such as pyridine, imidazole, and piperidine; and quaternary ammonium ions such as tetramethylammonium and tetrabutylammonium. These metal cations and ammonium ions can be used alone or in combination of two or more.

[0075] Since fine fibers can be obtained during spinning, R in general formula (8) 14 , R in general formula (9) 19 , R in general formula (10) 24 It is also preferable that 30 mol % or more, more preferably 50 mol % or more of them have a structure represented by the general formula (6) or general formula (7), typically a group selected from the structure represented by the general formula (6) or general formula (7).

[0076] (a-3) A heat-resistant resin having a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain. A heat-resistant resin having a group selected from a ketone group, a sulfone group, and a sulfide group in its main chain refers to a resin in which aromatic rings such as phenyl groups or naphthyl groups, or heterocycles are connected by these linking groups to form a polymer main chain, and which has a 5% weight loss temperature of 200°C or higher.

[0077] Preferred examples of the heat-resistant resin having at least one linking group selected from a ketone group, a sulfone group, and a sulfide group in the main chain include polyether ketone, polyether ether ketone, polyether sulfone, and polyphenylene sulfide.

[0078] (a-4) A precursor of a heat-resistant resin having a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain. Preferable examples of the heat-resistant resin precursor having a group selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain include a polyether ketone precursor, a polyether ether ketone precursor, a polyether sulfone precursor, a polyphenylene sulfide precursor, etc. When using each of these precursors, after spinning, they can be converted into the corresponding heat-resistant resin by heat treatment at 120 to 500°C for dehydration and ring closure.

[0079] (b) Solvent The solvent (b) used in the resin composition of the present invention is not particularly limited as long as it can dissolve the resin (a). The solvent used as the reaction solvent in producing the resin can also be used as is.

[0080] In this case, in addition to the reaction solvent described above, a poor solvent may be contained to the extent that the resin does not precipitate. Examples of the solvent that can be used in this case include ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether; ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propyl acetate, and butyl acetate; Examples of suitable solvents include, but are not limited to, ester solvents such as acetone, isobutyl acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl lactate, ethyl lactate, and butyl lactate; ketones such as acetylacetone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, cyclopentanone, and 2-heptanone; alcohols such as butyl alcohol, isobutyl alcohol, pentanol, 4-methyl-2-pentanol, 3-methyl-2-butanol, 3-methyl-3-methoxybutanol, and diacetone alcohol; aromatic hydrocarbons such as toluene and xylene; and water. These can be used alone or in combination.

[0081] (c) Surfactants having fluoroalkyl groups The resin composition of the present invention contains (c) a surfactant having a fluoroalkyl group, which reduces the surface tension of the resin composition and stabilizes spinning, thereby suppressing the occurrence of "beads," which are lump-like defects in which the fiber diameter suddenly increases.

[0082] The fluoroalkyl group is a group containing a perfluoro group, and the number of carbon atoms in the perfluoro group is preferably 3 or more, more preferably 4 or more, from the viewpoint of increasing the effect of reducing surface tension. Furthermore, from the viewpoint of generating appropriate charge repulsion during electrospinning and adjusting the fiber system to a more preferred range, the number of carbon atoms is preferably 12 or less, more preferably 8 or less.

[0083] The number of fluoroalkyl groups contained in one molecule of the surfactant compound is preferably 1 to 3, and more preferably 1 to 2.

[0084] From the viewpoint of further suppressing bead formation, it is preferable to use (c) a surfactant having a fluoroalkyl group that has at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen. These groups are thought to contribute to stabilization during spinning by interacting with the carbonyl groups and nitrogen of the resin.

[0085] Specific examples of preferred oxyethylene and oxypropylene groups are those in which n4 and n5 in the structures represented by the following general formulae (11) and (12) are 2 to 20, and more preferably 2 to 11.

[0086] [ka]

[0087] [ka]

[0088] Examples of the group containing a quaternary nitrogen include a quaternary ammonium structure and an amine oxide structure. From the viewpoint of reducing beads, the amine oxide structure is more preferred.

[0089] Furthermore, in terms of electrospinning, from the viewpoint of promoting liquid splitting due to charge repulsion during spinning and contributing to fiber thinning, it is preferable to use (c) a surfactant having a fluoroalkyl group that has at least one structure selected from a carboxyl group, a sulfonic group, a hydroxyl group, a carboxylate, a sulfonic acid salt, and a phenolic hydroxyl salt, and more preferably, (c) a surfactant having a fluoroalkyl group that has at least one structure selected from a carboxyl group and a hydroxyl group.

[0090] A surfactant having a fluoroalkyl group having at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen, and a surfactant having a fluoroalkyl group having at least one structure selected from a carboxyl group, a sulfonic group, a hydroxyl group, a carboxylate, a sulfonic acid salt, and a phenolic hydroxyl salt, can be preferably used in combination.

[0091] In addition, from the viewpoint of further reducing beads, it is preferable that (c) the surfactant having a fluoroalkyl group does not have a structure in which repeating units containing a fluoroalkyl group are linked.

[0092] Here, the structure in which repeating units containing a fluoroalkyl group are linked refers to a structure obtained by linking five or more fluoroalkyl group-containing compounds as monomers through a polymerization reaction such as addition polymerization or polycondensation. Examples of such structures include oligomers or polymers in which five or more repeating units having a fluoroalkyl group in the side chain are repeated, as shown in the following formula:

[0093] [ka]

[0094] On the other hand, for example, those containing multiple fluoroalkyl groups in one molecule rather than as repeating units, as shown in the following formula, or those containing repeating structures in one molecule but not containing fluoroalkyl groups, are not considered to be structures in which repeating units containing fluoroalkyl groups are linked.

[0095] [ka]

[0096] [ka]

[0097] (c) Preferred examples of the surfactant having a fluoroalkyl group include the compounds shown below.

[0098] [ka]

[0099] In general formula (13), R 26 represents a monovalent group having 1 to 6 carbon atoms. n6 represents an integer of 1 to 15, n7 represents an integer of 1 to 4, and n8 represents an integer of 2 to 10,000.

[0100] [ka]

[0101] In the general formula (14), n9 represents an integer of 1 to 15, 10 represents an integer of 1 to 4. Y1 represents a group selected from a carboxyl group, a sulfonic acid group, a hydroxyl group, a carboxylate structure, a sulfonate structure, and a phenolic hydroxyl salt structure.

[0102] [ka]

[0103] In general formula (15), n 11 represents an integer from 1 to 15, and n 12 represents an integer from 1 to 4, and n 13 represents an integer of 1 to 20. Y2 represents a group selected from a carboxyl group, a sulfonic acid group, and a hydroxyl group, including metal salts thereof such as alkali metal salts and alkaline earth metal salts.

[0104] [ka]

[0105] In general formula (16), n 14 and n18 each independently represents an integer of 1 to 15, and n15 and n 17 each independently represents an integer of 1 to 4, and n 16 represents an integer from 1 to 20.

[0106] [ka]

[0107] In general formula (17), n 19 and n 21 each independently represents an integer of 1 to 15, and n20 and n 22 each independently represents an integer of 1 to 4, and n 23 represents an integer of 1 to 20. Y3 represents a direct bond, an ether group, or a thioether group. Y4 represents a group selected from a carboxyl group, a sulfonic acid group, and a hydroxyl group, including metal salts thereof such as alkali metal salts and alkaline earth metal salts.

[0108] [ka]

[0109] In general formula (18), n 24 represents an integer from 1 to 15, and n 25 represents an integer from 1 to 4, and n 26 represents an integer of 1 to 8. Y5 represents a direct bond, an ether group, or a thioether group. Y6 represents a group selected from a carboxyl group, a sulfonic acid group, and a hydroxyl group, including metal salts thereof such as alkali metal salts and alkaline earth metal salts.

[0110] [ka]

[0111] In general formula (19), R 27 and R 28 R each independently represents a divalent group having 1 to 6 carbon atoms. 29 and R 30each independently represents a monovalent group having 1 to 6 carbon atoms; Y7 represents a direct bond, an ether group, a thioether group, -NH-, or -NR 31 - represents a group selected from R 31 represents a monovalent group having 1 to 6 carbon atoms. 27 represents an integer from 1 to 15.

[0112] In general formulas (13) to (19), n6, n9, n 11 , n 14 , n 18 , n 19 , n 21 , n 24 and n 27 From the viewpoint of increasing the effect of reducing surface tension, the number is preferably 3 or more, and more preferably 4 or more. From the viewpoint of thinning the fiber diameter, the number is preferably 12 or less, and more preferably 8 or less.

[0113] In general formulas (13) to (18), n7, n 10 , n 12 , n 15 , n 17 , n 20 , n22 and n 25 is preferably 2 from the viewpoint of the effect of reducing surface tension.

[0114] In general formula (18), n 26 is preferably 2 to 4 from the viewpoint of the effect of reducing the surface tension.

[0115] In general formulas (15) to (17), n 13 , n 16 and n 23 is preferably 2 to 15, and even more preferably 2 to 11, from the viewpoint of reducing beads.

[0116] In the general formulae (14), (15), (17) and (18), Y1, Y2, Y4 and Y6 are preferably groups selected from a carboxyl group and a hydroxyl group from the viewpoint of thinning the fiber diameter.

[0117] In general formula (19), R 27 and R 28From the viewpoint of the effect of reducing the surface tension, R is preferably a group having 1 to 4 carbon atoms. 27 is more preferably a group having 1 to 4 carbon atoms and containing a hydroxyl group or a carboxyl group in the side chain.

[0118] In general formula (19), R 29 , R 30 and R 31 From the viewpoint of the effect of reducing surface tension, is preferably a group having 1 to 3 carbon atoms. Preferred examples include a methyl group, an ethyl group, and an isopropyl group.

[0119] In addition, R 26 ~R 31 is typically a residue of an aliphatic hydrocarbon, an aromatic hydrocarbon, or a nitrogen-containing aromatic hydrocarbon, and also includes those in which these are bonded together via a linking group such as a single bond, an ether bond, a thioether bond, an ester bond, a ketone bond, or a sulfone bond, and those in which some of the hydrogen atoms have been substituted with a monovalent functional group such as an alkyl group, an oxyalkyl group, an oxyaryl group, a nitro group, or a cyano group.

[0120] Particularly preferred examples of (c) surfactants having a fluoroalkyl group are the compounds shown below.

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] In the composition of the present invention for forming a nonwoven fabric by electrospinning, the content of (c) the surfactant having a fluoroalkyl group in the composition is preferably 0.3 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1 to 3% by mass. When this content is equal to or greater than the lower limit, the frequency of nodular defects occurring in the fiber during electrospinning can be further reduced. Furthermore, when this content is equal to or less than the upper limit, charge repulsion during electrospinning falls within an appropriate range, making it easier to obtain threads with a small fiber diameter.

[0127] <Nonwoven fabric> The nonwoven fabric of the present invention comprises (a) at least one heat-resistant resin or a precursor thereof selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having at least one group selected from ether groups, ketone groups, sulfone groups, and sulfide groups in the main chain, and (c) a surfactant having a fluoroalkyl group, where the details of components (a) and (c) are as described above.

[0128] Furthermore, when a nonwoven fabric is made from a precursor of a heat-resistant resin, it can be converted into a heat-resistant resin by further undergoing thermal or chemical treatment such as crosslinking, thermal ring closure, or chemical ring closure.

[0129] The inclusion of component (c) in the nonwoven fabric enhances the bonding between the fibers due to the hydrophobic interaction of the fluoroalkyl groups unevenly distributed on the fiber surfaces, thereby improving the toughness of the nonwoven fabric. Furthermore, when the nonwoven fabric is subjected to heat treatment after formation, the bonding between the polymer fibers is further strengthened through the fusion of the fluoroalkyl groups.

[0130] Such a nonwoven fabric can be obtained, for example, by spinning a resin composition containing (a) at least one heat-resistant resin selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having at least one group selected from an ether group, a ketone group, a sulfone group, and a sulfide group in the main chain, or a precursor thereof, (b) a solvent, and (c) a surfactant having a fluoroalkyl group, which is melted or dissolved in a solvent.

[0131] As a spinning method, electrospinning is preferably used because the liquid is split during spinning, resulting in a nonwoven fabric made of fibers with a finer fiber diameter. That is, it is preferable to form a nonwoven fabric by spinning the above-mentioned resin composition by electrospinning.

[0132] The electrospinning method used here is a spinning method in which a high voltage is applied to a polymer solution and the charged polymer solution is sprayed onto a grounded counter electrode to obtain ultrafine fibers. The electrospinning device used in the present invention is not particularly limited, but examples include a device that ejects a polymer solution from a protruding nozzle like a syringe, and a device that ejects ultrafine fibers from a discharge section by charging a thin film of polymer solution formed on a rotating roller or ball. The liquid is ejected while applying a voltage to the discharge section, and a nonwoven fabric is deposited on the substrate by attaching aluminum foil or release paper to the grounded counter electrode.

[0133] Furthermore, nonwoven fabrics formed from resin compositions containing the above general formulas (1) to (5) do not require heat treatment for dehydration and ring closure after spinning, and nonwoven fabrics with excellent heat resistance and mechanical properties can be obtained extremely easily.

[0134] On the other hand, when a nonwoven fabric is formed using a precursor of a heat-resistant resin, the precursor of the heat-resistant resin usually has a high affinity for a solvent and therefore has excellent spinnability, and by utilizing this property, a nonwoven fabric with a fineness can be obtained. Furthermore, by converting the precursor of the heat-resistant resin into a heat-resistant resin, a nonwoven fabric with excellent heat resistance and mechanical properties can be obtained.

[0135] A nonwoven fabric with excellent mechanical strength is resistant to breakage and will not break even when the volume of the electrode changes during battery assembly or charging / discharging. From this perspective, the tensile strength of the nonwoven fabric is preferably 1.0 N / cm or more, more preferably 1.5 N / cm or more, even more preferably 2.0 N / cm or more, and particularly preferably 2.5 N / cm or more. There is no particular upper limit to the tensile strength, but it is preferably 5.0 N / cm or less.

[0136] The fiber diameter in the nonwoven fabric is preferably 3 μm or less, more preferably 1.5 μm or less, and even more preferably 1 μm or less. The smaller the fiber diameter, the more the nonwoven fabric can be kept dense and strong, while improving the porosity and ensuring high breathability and liquid permeability.

[0137] The fiber diameter referred to here is determined by observing the nonwoven fabric under a scanning electron microscope (SEM) at an appropriate magnification (for example, 10,000x), randomly selecting 30 fibers within the field of view, measuring their widths, and then calculating the arithmetic mean.

[0138] <Applications of nonwoven fabric> The nonwoven fabric according to the embodiment of the present invention can be suitably used for textile products such as separators for electric storage devices such as secondary batteries or electric double layer capacitors, sound absorbing materials, electromagnetic wave shielding materials, separation filters, heat-resistant bag filters, etc. In particular, when used as a separator for an electric storage device, the nonwoven fabric can improve the safety of the electric storage device as a separator with high heat resistance.

[0139] The secondary battery or electric double layer capacitor according to the embodiment of the present invention has the above-described separator between the positive electrode and the negative electrode. Such a secondary battery or electric double layer capacitor can be obtained by stacking a plurality of electrodes with the above-described separator interposed therebetween, placing them together with an electrolyte in an exterior material such as a metal case, and sealing the stack. [Example]

[0140] The present invention will be described below with reference to examples and techniques, but the present invention is not limited to these examples.

[0141] Synthesis Example 1 (Polyethersulfone solution) In a 500 mL flask equipped with a Dean-Stark trap, 22.8 g (0.1 mol) of bisphenol A (Tokyo Chemical Industry Co., Ltd.), 28.7 g (0.1 mol) of bis(4-chlorophenyl)sulfone (Tokyo Chemical Industry Co., Ltd.), 17.3 g (0.125 mol) of potassium carbonate (Tokyo Chemical Industry Co., Ltd.), 150 g of N,N-dimethylacetamide (Tokyo Chemical Industry Co., Ltd., DMAc), and 80 g of toluene (Tokyo Chemical Industry Co., Ltd.) were added under a dry nitrogen stream and refluxed for 6 hours with stirring to remove water. The excess toluene was then removed under reduced pressure, and the remaining mixture was stirred at 160°C for 12 hours. The reaction mixture was then cooled to 100°C, and 100 g of chlorobenzene (Tokyo Chemical Industry Co., Ltd.) was added. The precipitate was then filtered off. The filtrate was neutralized with acetic acid (Tokyo Chemical Industry Co., Ltd.) and then poured into 3 L of a 1 / 1 (mass ratio) solution of pure water and methanol (Tokyo Chemical Industry Co., Ltd.) to precipitate the polymer, which was then filtered off. The precipitate was further dispersed in 3 L of a 1 / 1 (mass ratio) solution of pure water and methanol, filtered, then dispersed in 3 L of pure water, filtered, and finally refluxed in boiling water for 1 hour. The powder filtered out after reflux was dried under reduced pressure at 100°C for 72 hours, and 14 g of the dried polymer solid was dissolved in 26 g of DMAc to obtain a 35% polyethersulfone solution (PES-01).

[0142] Synthesis Example 2 (Polyimide precursor solution) Under a dry nitrogen stream, 10.8 g (0.1 mol) of paraphenylenediamine (PDA, manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 50 g of DMAc in a 200 mL flask. 27.9 g (0.095 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA, manufactured by Tokyo Chemical Industry Co., Ltd.) was added together with 21.9 g of DMAc. The mixture was stirred at 60°C for 5 hours and then cooled to room temperature to obtain a polyimide precursor solution (PAA-01) with a polymer concentration of 35% by mass.

[0143] Synthesis Example 3 (Polyimide solution) Under a dry nitrogen stream, 33.0 g (0.09 mol) of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BAHF, manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 100 g of N-methyl-2-pyrrolidone (NMP, manufactured by Tokyo Chemical Industry Co., Ltd.) in a 300 mL flask. 31.0 g (0.1 mol) of 3,3',4,4'-diphenylethertetracarboxylic acid dianhydride (ODPA, manufactured by Tokyo Chemical Industry Co., Ltd.) was added together with 12.8 g of NMP and stirred at 40°C for 2 hours. After stirring at 200°C for 6 hours, the temperature was lowered to room temperature to obtain a polyimide solution (PI-01) with a polymer concentration of 35% by mass.

[0144] Synthesis Example 4 (Polyamideimide precursor solution) Under a dry nitrogen stream, 20.0 g (0.1 mol) of diaminodiphenyl ether (DAE, manufactured by Tokyo Chemical Industry Co., Ltd.) and 11.1 g (0.11 mol) of triethylamine (TEA, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 100 g of NMP in a 300 mL flask. To this solution, 20.0 g (0.095 mol) of trimellitic anhydride chloride (TMC, manufactured by Tokyo Chemical Industry Co., Ltd.) was added along with 20 g of NMP and stirred at 0 °C for 5 hours. After stirring, the triethylamine hydrochloride that had precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The precipitated polymer solid was collected by filtration. The polymer solid was washed three times with 2 L of water and then dried in a vacuum dryer at 50 °C for 72 hours. 7 g of the dried polymer solid was dissolved in 13 g of DMAc to obtain a polyamideimide precursor solution (PAIA-01) with a polymer concentration of 35% by mass.

[0145] Synthesis Example 5 (Polyamideimide solution) Under a dry nitrogen stream, 5.23 g (0.03 mol) of 2,4-toluene diisocyanate (Tokyo Chemical Industry Co., Ltd., TDI) and 17.5 g (0.07 mol) of diphenylmethane diisocyanate (Tokyo Chemical Industry Co., Ltd., MDI) were dissolved in 55 g of DMAc in a 300 mL flask. To this was added 18.3 g (0.095 mol) of trimellitic anhydride (Tokyo Chemical Industry Co., Ltd., TMA) along with 5.67 g of DMAc, and the mixture was stirred at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain a polyamideimide solution (PAI-01) with a polymer concentration of 35% by mass.

[0146] Synthesis Example 6 (Polyamide Solution) Under a dry nitrogen stream, 22.2 g (0.1 mol) of isophorone diisocyanate (IHDI, manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 50 g of NMP in a 200 mL flask. 16.6 g (0.1 mol) of isophthalic acid (IPA, manufactured by Tokyo Chemical Industry Co., Ltd.) was added together with 5.71 g of NMP, and the mixture was stirred at 200°C for 6 hours. After stirring, the mixture was cooled to room temperature, yielding a polyamide solution (PA-01) with a polymer concentration of 35% by mass.

[0147] Synthesis Example 7 (Polyurea solution) Under a dry nitrogen stream, 10.8 g (0.1 mol) of PDA was dissolved in 50 g of DMAc in a 200 mL flask. 21.3 g (0.096 mol) of IHDI was added together with 9.61 g of DMAc, and the mixture was stirred at 40°C for 6 hours. After stirring, the mixture was cooled to room temperature to obtain a polyurea solution (PU-01) with a polymer concentration of 35% by mass.

[0148] Synthesis Example 8 (Polybenzoxazole precursor solution) Under a dry nitrogen stream, 36.6 g (0.1 mol) of BAHF and 21.2 g (0.21 mol) of TEA were dissolved in 150 g of NMP in a 500 mL flask. To this solution, 28.3 g (0.096 mol) of 4,4'-diphenyl ether dicarboxylic acid chloride (DEDC, Tokyo Chemical Industry Co., Ltd.) was added along with 44.7 g of NMP and stirred at 5°C for 6 hours. The triethylamine hydrochloride that precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The polymer solid precipitate was collected by filtration. The polymer solid was washed three times with 2 L of water and then dried in a vacuum oven at 50°C for 72 hours. 14 g of the dried polymer solid was dissolved in 26 g of DMAc to obtain a 35% polybenzoxazole precursor solution (PBOA-01).

[0149] Synthesis Example 9 (Polybenzoxazole solution) Under a dry nitrogen stream, 36.6 g (0.1 mol) of BAHF and 21.2 g (0.21 mol) of TEA were dissolved in 200 g of NMP in a 500 mL flask. 37.7 g (0.096 mol) of 2,2'-bis(4-carboxyphenyl)hexafluoropropane (Tokyo Chemical Industry Co., Ltd., 6FDC) was added along with 22.9 g of NMP and stirred at 40 °C for 2 hours. After stirring, triethylamine hydrochloride precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The polymer solid precipitate was collected by filtration. The polymer solid was washed three times with 2 L of water and then dried in a vacuum oven at 50 °C for 72 hours. 28 g of the dried polymer solid was dissolved in 52 g of NMP and stirred at 200 °C for 6 hours. The mixture was then cooled to room temperature to obtain a polybenzoxazole solution (PBO-01) with a polymer concentration of 35% by mass.

[0150] Synthesis Example 10 (Polybenzothiazole precursor solution) Under a dry nitrogen stream, 24.5 g (0.1 mol) of 2,5-dimercapto-1,4-phenylenediamine dihydrochloride (Tokyo Chemical Industry Co., Ltd., SHPDA) and 41.4 g (0.41 mol) of TEA were dissolved in 100 g of NMP in a 300 mL flask. 28.3 g (0.096 mol) of DEDC was added along with 58.4 g of NMP and the mixture was stirred at 5°C for 6 hours. The triethylamine hydrochloride precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The polymer solid precipitate was collected by filtration. The polymer solid was washed three times with 2 L of water and then dried in a vacuum oven at 50°C for 72 hours. 14 g of the dried polymer solid was dissolved in 26 g of DMAc to obtain a polybenzothiazole precursor solution (PBTA-01) with a polymer concentration of 35% by mass.

[0151] Synthesis Example 11 (Polybenzimidazole precursor solution) Under a dry nitrogen stream, 21.4 g (0.1 mol) of 3,3'-diaminobenzidine (Tokyo Chemical Industry Co., Ltd., DABZ) and 21.2 g (0.21 mol) of TEA were dissolved in 100 g of NMP in a 300 mL flask. To this solution, 28.3 g (0.096 mol) of DEDC was added along with 49.1 g of NMP, and the mixture was stirred at 5°C for 6 hours. The triethylamine hydrochloride that precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The polymer solid precipitate was collected by filtration. The polymer solid was washed three times with 2 L of water, and the collected polymer solid was dried in a vacuum oven at 50°C for 72 hours. 14 g of the dried polymer solid was dissolved in 26 g of DMAc to obtain a 35% by weight polybenzimidazole precursor solution (PBIA-01).

[0152] Synthesis Example 12 (Polyimide precursor solution) Under a dry nitrogen stream, 14.0 g (0.07 mol) of DAE and 3.67 g (0.03 mol) of 2,4-diaminotoluene (TDA, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 70 g of DMAc in a 200 mL flask. 27.9 g (0.095 mol) of BPDA was added together with 14.6 g of DMAc, and the mixture was stirred at 60°C for 5 hours and then cooled to room temperature to obtain a polyimide precursor solution (PAA-02) with a polymer concentration of 35% by mass.

[0153] Synthesis Example 13 (Polyimide precursor solution) In a 200 mL flask, 10.0 g (0.05 mol) of DAE and 10.6 g (0.05 mol) of o-tolidine (o-TODA, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 70 g of DMAc under a dry nitrogen stream. 20.7 g (0.095 mol) of pyromellitic anhydride (PMDA, manufactured by Tokyo Chemical Industry Co., Ltd.) was added together with 6.70 g of DMAc. The mixture was stirred at 60°C for 5 hours and then cooled to room temperature to obtain a polyimide precursor solution (PAA-03) with a polymer concentration of 35% by mass.

[0154] Synthesis Example 14 (Polyimide Solution) Under a dry nitrogen stream, 9.54 g (0.045 mol) of m-tolidine (manufactured by Tokyo Chemical Industry Co., Ltd., m-TODA) and 11.2 g (0.045 mol) of 3,3-diaminodiphenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd., 3-DDS) were dissolved in 80 g of NMP in a 300 mL flask. 31.0 g (0.1 mol) of ODPA was added together with 10.1 g of NMP, and the mixture was stirred at 40°C for 2 hours. After further stirring at 200°C for 6 hours, the mixture was cooled to room temperature to obtain a polyimide solution (PI-02) with a polymer concentration of 35% by mass.

[0155] Synthesis Example 15 (Polyimide Solution) In a 300 mL flask, 12.7 g (0.045 mol) of 4,4'-methylenebis(2-ethyl-6-methylaniline) (Tokyo Chemical Industry Co., Ltd., MEDX) and 3- 11.2 g (0.045 mol) of DDS was dissolved in 80 g of NMP. 10.9 g (0.05 mol) of PMDA and 16.1 g (0.05 mol) of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA, manufactured by Tokyo Chemical Industry Co., Ltd.) were added together with 8.51 g of NMP, and the mixture was stirred at 40°C for 2 hours. After stirring at 200°C for 6 hours, the mixture was cooled to room temperature to obtain a polyimide solution (PI-03) with a polymer concentration of 35% by mass.

[0156] Synthesis Example 16 (Polyimide Solution) Under a dry nitrogen stream, 14.9 g (0.06 mol) of 3-DDS and 3.67 g (0.03 mol) of TDA were dissolved in 80 g of NMP in a 300 mL flask. 31.0 g (0.1 mol) of ODPA was added together with 6.04 g of NMP, and the mixture was stirred at 40°C for 2 hours. After stirring at 200°C for 6 hours, the mixture was cooled to room temperature to obtain a polyimide solution (PI-04) with a polymer concentration of 35% by mass.

[0157] Synthesis Example 17 (Polyamideimide precursor solution) Under a dry nitrogen stream, 10.0 g (0.05 mol) of DAE, 10.6 g (0.05 mol) of m-TODA, and 11.1 g (0.11 mol) of triethylamine (TEA, manufactured by Tokyo Chemical Industry Co., Ltd.) were dissolved in 100 g of NMP in a 300 mL flask. To this solution, 20.0 g (0.095 mol) of TMC was added along with 21.8 g of NMP, and the mixture was stirred at 0°C for 5 hours. After stirring, the triethylamine hydrochloride that had precipitated in the solution was filtered off, and the filtrate was poured into 2 L of water. The precipitated polymer solid was collected by filtration. The polymer solid was washed three times with 2 L of water, and the collected polymer solid was dried in a vacuum dryer at 50°C for 72 hours. 7 g of the dried polymer solid was dissolved in 13 g of DMAc to obtain a 35 wt% polyamideimide precursor solution (PAIA-02).

[0158] Synthesis Example 18 (Polyamideimide Solution) Under a dry nitrogen stream, 13.2 g (0.05 mol) of o-tolidine diisocyanate (Tokyo Chemical Industry Co., Ltd., TODI) and 12.5 g (0.05 mol) of MDI were dissolved in 60 g of DMAc in a 300 mL flask. 18.3 g (0.095 mol) of TMA was added along with 6.19 g of DMAc, and the mixture was stirred at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain a polyamideimide solution (PAI-02) with a polymer concentration of 35% by mass.

[0159] Synthesis Example 19 (Polyamideimide Solution) Under a dry nitrogen stream, 25.0 g (0.1 mol) of MDI was dissolved in 60 g of DMAc in a 300 mL flask. 18.3 g (0.095 mol) of TMA was added together with 4.89 g of DMAc, and the mixture was stirred at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours. After stirring, the mixture was cooled to room temperature to obtain a polyamideimide solution (PAI-03) with a polymer concentration of 35% by mass.

[0160] Synthesis Example 20 (Polyamide Solution) Under a dry nitrogen stream, 15.5 g (0.07 mol) of IHDI and 5.23 g (0.03 mol) of TDI were dissolved in 45 g of NMP in a 200 mL flask. 16.6 g (0.1 mol) of IPA was added along with 7.98 g of NMP, and the mixture was stirred at 200 °C for 6 hours. After stirring, the mixture was cooled to room temperature to obtain a polyamide solution (PA-02) with a polymer concentration of 35% by mass.

[0161] Synthesis Example 21 (Polyamide Solution) Under a dry nitrogen stream, 11.1 g (0.05 mol) of IHDI and 8.71 g (0.05 mol) of TDI were dissolved in 45 g of NMP in a 200 mL flask. 16.6 g (0.1 mol) of IPA and 6.28 g of NMP were added, and the mixture was stirred at 200 °C for 6 hours. After stirring, the temperature was lowered to room temperature, yielding a polyamide solution (PA-03) with a polymer concentration of 35% by mass.

[0162] Synthesis Example 22 (Polyurea solution) Under a dry nitrogen stream, 14.0 g (0.07 mol) of DAE and 3.67 g (0.03 mol) of TDA were dissolved in 60 g of DMAc in a 200 mL flask. 21.3 g (0.096 mol) of IHDI was added along with 12.4 g of DMAc, and the mixture was stirred at 40°C for 6 hours. After stirring, the mixture was cooled to room temperature, yielding a polyurea solution (PU-02) with a polymer concentration of 35% by mass.

[0163] Synthesis Example 23 (Polyurea solution) Under a dry nitrogen stream, 5.4 g (0.05 mol) of PDA and 10.6 g (0.05 mol) of o-TODA were dissolved in 60 g of DMAc in a 200 mL flask. 21.3 g (0.096 mol) of IHDI was added along with 9.27 g of DMAc, and the mixture was stirred at 40°C for 6 hours. After stirring, the mixture was cooled to room temperature, yielding a polyurea solution (PU-03) with a polymer concentration of 35% by mass.

[0164] Synthesis Example 24 (Surfactant A: having a structure in which repeating units containing fluoroalkyl groups are linked together) 150 g of xylene was placed in a 500 ml flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel, and the liquid temperature was maintained at 110°C. Under a nitrogen atmosphere, a mixed solution of 60 g (0.18 mol) of 2-(perfluorobutyl)ethyl methacrylate (Fujifilm Wako Chemical Co., Ltd.), 2 g (0.02 mol) of methyl methacrylate (Tokyo Chemical Industry Co., Ltd.), 38 g (0.2 mol) of n-butoxyethyl methacrylate (Tokyo Chemical Industry Co., Ltd.), and 1 g of Perocta O (NOF Corporation) was added dropwise to the xylene over approximately 1 hour. The mixture was allowed to react at 110°C for 2 hours, yielding Compound A shown below.

[0165] [ka]

[0166] Synthesis Example 25 (Surfactant B: containing a fluoroalkyl group and an oxyethylene group) In a 200 ml flask equipped with a stirrer and a dropping funnel, 26.4 g (0.1 mol) of 1H,1H,2H,2H-nonafluoro-1-hexanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 16.0 g (0.05 mol) of bis(2-(2-(2-chloroethoxy)ethoxy)ethyl)ether (manufactured by Tokyo Chemical Industry Co., Ltd.) were added dropwise at room temperature to a mixture of 19.3 g (0.1 mol) of a 28% sodium methoxide methanol solution. The mixture was further heated and stirred at 80°C for 5 hours. After the reaction was completed, 300 ml of ethyl acetate was added, and the organic layer was washed three times with 150 ml of 20% brine. After drying over 30.0 g of anhydrous magnesium sulfate, the solvent was evaporated under reduced pressure to obtain the following compound B.

[0167] [ka]

[0168] Synthesis Example 26 (Surfactant C: containing a fluoroalkyl group, an oxyethylene group, and a hydroxyl group) In a 200 ml flask equipped with a stirrer and a dropping funnel, 46.4 g (0.1 mol) of 1H,1H,2H,2H-heptadecafluoro-1-decanol (Tokyo Chemical Industry Co., Ltd.) and 16.9 g (0.1 mol) of 2-(2-(2-chloroethoxy)ethoxy)ethanol (Tokyo Chemical Industry Co., Ltd.) were added dropwise at room temperature to a mixture of 19.3 g (0.1 mol) of 28% sodium methoxide in methanol. The mixture was then heated and stirred at 80°C for 5 hours. After the reaction was completed, 300 ml of ethyl acetate was added, and the organic layer was washed three times with 150 ml of 20% brine. After drying over 30.0 g of anhydrous magnesium sulfate, the solvent was removed by distillation under reduced pressure to obtain the following compound C.

[0169] [ka]

[0170] Synthesis Example 27 (Surfactant D: containing a fluoroalkyl group, an oxyethylene group, and a hydroxyl group) A 200 ml flask equipped with a stirrer and a Dean-Stark trap was charged with 26.4 g (0.1 mol) of 1H,1H,2H,2H-nonafluoro-1-hexanol, 6.7 g (0.05 mol) of malic acid (Tokyo Chemical Industry Co., Ltd.), 5.0 g of concentrated sulfuric acid, and 100 ml of toluene. The mixture was heated under reflux until the theoretical amount of water (1.8 g) was removed. After cooling to 60 °C, 4 g of hydrated lime was added and the mixture was stirred at the same temperature for 30 minutes. After filtration, the toluene was removed by distillation under reduced pressure to obtain the diester [malic acid di-(1H,1H,2H,2H-nonafluoro-1-hexyl) ester] as a transparent yellow viscous liquid.

[0171] In a 200 ml flask equipped with a stirrer and a dropping funnel, 19.3 g (0.1 mol) of a 28% sodium methoxide methanol solution was added dropwise at room temperature to a mixture of 31.3 g (0.1 mol) of the diester obtained above and 16.9 g (0.1 mol) of 2-(2-(2-chloroethoxy)ethoxy)ethanol. The mixture was further heated and stirred at 80°C for 5 hours. After the reaction was completed, 300 ml of ethyl acetate was added, and the organic layer was washed three times with 150 ml of 20% brine. After drying with 30.0 g of anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to obtain the following compound D.

[0172] [ka]

[0173] Synthesis Example 28 (Surfactant E: containing a fluoroalkyl group and a carboxyl group) In a 1L flask equipped with a stirrer, reflux condenser, and dropping funnel, 57.4g (0.1 mol) of 1H,1H,2H,2H-heptadecafluorodecyl iodide (Tokyo Chemical Industry Co., Ltd.), 27.6g of anhydrous potassium carbonate, and 400ml of acetone were added and mixed, and then 16.0g (0.12 mol) of 2-mercaptopropionic acid ethyl ester (Tokyo Chemical Industry Co., Ltd.) was added dropwise over 10 minutes, followed by stirring at room temperature for 5 hours to allow the reaction to proceed. The resulting reaction mixture was filtered, and the acetone was distilled off. After further distillation under reduced pressure to remove raw materials, 1H,1H,2H,2H-heptadecafluorodecyl mercaptopropionic acid ethyl ester was obtained.

[0174] In a 300 ml flask equipped with a stirrer, a reflux condenser, and a thermometer, 22.0 g (0.38 mol) of the obtained 1H,1H,2H,2H-heptadecafluorodecyl mercaptopropionic acid ethyl ester, 1.35 g of lithium hydroxide, and 50 ml of water were added, and the mixture was heated at 80° C. for 4 hours. The mixture was stirred for 1 hour to allow the reaction to proceed. The reaction mixture was acidified with 1N hydrochloric acid, and then 300 ml of ethyl acetate was added to extract the organic layer. The extracted organic layer was washed three times with 150 ml of 20% brine. After drying with 30.0 g of anhydrous magnesium sulfate, the solvent was distilled off under reduced pressure to obtain the following compound E.

[0175] [ka]

[0176] Synthesis Example 29 (Surfactant F: containing a fluoroalkyl group and a sulfonate structure) Into a 2 L flask equipped with a stirrer, a reflux condenser, and a thermometer, 480.2 g (1 mol) of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanethiol (Sigma-Aldrich) and 149.8 g (1.1 mol) of 1,4-butanesultone (Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was stirred under a nitrogen atmosphere. The mixture was stirred at 120°C for 4 hours, then cooled to 25°C, and 10% by weight of lithium hydroxide was added to the reaction mixture. 460 g of an aqueous solution of ammonium hydroxide was added. After stirring at 25°C for 30 minutes, water was distilled off under reduced pressure. The resulting compound was recrystallized from methanol to obtain the following compound F.

[0177] [ka]

[0178] Synthesis Example 30 (Surfactant G: containing a fluoroalkyl group, an amine oxide group, and a hydroxyl group) A 100 ml flask was charged with 47.6 g (0.1 mol) of 1,2-epoxy-1H,1H,2H,3H,3H-heptadecafluoroundecane (Fujifilm Wako Chemical Co., Ltd.) and 20.4 g (0.2 mol) of dimethylaminopropylamine (Tokyo Chemical Industry Co., Ltd.), and the mixture was heated to 60°C to react and then aged for 16 hours. Subsequently, excess amine was distilled off under reduced pressure at 80°C to obtain 55.8 g of the following compound.

[0179] [ka]

[0180] A 100 ml flask was charged with 9.79 g (0.0169 mol) of the above compound, 35 g of ethanol, and 5 g of ion-exchanged water, and the temperature was raised to 65° C. 2.68 g (0.0237 mol) of 30 wt % hydrogen peroxide solution was added dropwise thereto, and the mixture was aged at the same temperature for 4 hours to obtain the following compound G.

[0181] [ka]

[0182] Synthesis Example 31 (Surfactant H: Silicone Compound) A 1-L flask equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen gas inlet was charged with 100 g of cyclohexanone and heated to 110°C under a nitrogen gas atmosphere. While maintaining the cyclohexanone temperature at 110°C, a mixture of 90 g (0.91 mol) of N,N-dimethylacrylamide (Tokyo Chemical Industry Co., Ltd.), 10 g (0.01 mol) of Silaplane FM-0711 (JNC Corporation), 1 g of tert-butylperoxy-2-ethylhexanoate, 2 g of dodecyl mercaptan, and 200 g of cyclohexanone was added dropwise at a constant rate over 2 hours using the dropping funnel to prepare a monomer solution. After the addition was complete, the monomer solution was heated to 115°C and reacted for 2 hours to synthesize a copolymer, yielding the following compound H.

[0183] [ka]

[0184] Synthesis Example 32 (Surfactant I: Acrylic Compound) A 1-L flask equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen gas inlet was charged with 100 g of octanol and heated to 100°C under a nitrogen gas atmosphere. While maintaining the octanol temperature at 100°C, a mixture of 180 g (0.96 mol) of ethoxydiethylene glycol acrylate (Tokyo Chemical Industry Co., Ltd.), 120 g (0.65 mol) of 2-ethylhexyl acrylate (Tokyo Chemical Industry Co., Ltd.), 1 g of tert-butylperoxy-2-ethylhexanoate, and 100 g of octanol was added dropwise at a constant rate over 2 hours using the dropping funnel to synthesize a monomer solution. After the addition was completed, the monomer solution was heated to 115°C and reacted for 2 hours to synthesize a copolymer. The mixture was then diluted with octanol to a residual concentration of 50%, yielding Compound I below.

[0185] [ka]

[0186] Synthesis Example 33 (Surfactant J: Oxypropylene Compound) A 3 L flask equipped with a stirring blade, a nitrogen inlet tube, a thermocouple, a condenser, and an oil-water separator was charged with 700 g of xylitol (Tokyo Chemical Industry Co., Ltd.), 1291 g of 2,2-dimethoxypropane (Tokyo Chemical Industry Co., Ltd.), and 27 mg of paratoluenesulfonic acid monohydrate, and the reaction system was maintained at 60 to 90°C for 2 hours. After completion of the reaction, the by-product methanol and excess 2,2-dimethoxypropane were removed to obtain the following compound.

[0187] [ka]

[0188] 235 g of the above compound and 15.5 g of potassium hydroxide were charged into an autoclave, and the air in the autoclave was replaced with dry nitrogen. The catalyst was then completely dissolved at 140°C with stirring. Next, 2900 g of butylene oxide (Tokyo Chemical Industry Co., Ltd.) was added dropwise using a dropping device, and the mixture was stirred for 2 hours. The reaction mixture was then removed from the autoclave, neutralized with hydrochloric acid to a pH of 6 to 7, and subjected to reduced pressure treatment at 100°C for 1 hour to remove contained water. Finally, the mixture was filtered to remove salt, yielding the following compound.

[0189] [ka]

[0190] A 1-L flask equipped with a stirring blade, nitrogen inlet, thermocouple, and condenser was charged with 700 g of the above compound, 70 g of water, and 10 g of 36% hydrochloric acid. The deketalization reaction was carried out in a sealed state at 80°C for 2 hours, after which the water and acetone were distilled out of the system by nitrogen bubbling. The pH was then adjusted to 6-7 with a 10% aqueous potassium hydroxide solution, and the mixture was subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. After further treatment, filtration was carried out to remove the salt formed, yielding the following compound J.

[0191] [ka]

[0192] Example 2、4~6、9~15、17~23、25~34、36~ 40, Comparative Examples 1 to 16 , Reference examples 1 to 7 The evaluation was carried out according to the following procedure.

[0193] (1) Preparation of nonwoven fabric and observation during spinning To 20 g of the polymer solution obtained in each synthesis example, with a resin concentration of 35% by mass, 0.47 g of surfactant was added to obtain the composition shown in Tables 1 to 3. The composition was then diluted with the same solvent as the polymer solution to obtain a resin concentration of 30% by mass. The prepared compositions are shown in Tables 1 to 3.

[0194] The resin solution was discharged at 40 μL / min using an electrospinning device (NEU nanofiber electrospinning unit, manufactured by Kato Tech Co., Ltd.) and coated onto aluminum foil at a basis weight of 5 g / m. 2 The nonwoven fabric was formed so that the resin solution was uniformly dispersed. An 18-gauge (0.94 mm inner diameter) non-beveled needle was used for the nozzle, and the distance to the collector was 15 cm. When setting the voltage, the tip of the nozzle was visually inspected for each sample to ensure that the resin solution maintained a stable conical (Taylor cone) shape at the tip of the nozzle. The resulting nonwoven fabric on aluminum foil was vacuum dried at 150°C to remove residual solvent.

[0195] The whitening of the yarn during electrospinning was confirmed by visual observation, and yarns that did not show whitening were rated as passing. The results are shown in Tables 1 to 3.

[0196] (2) Observation of nonwoven fabric The nonwoven fabric obtained by the electrospinning method was observed with a scanning electron microscope (SEM). The accelerating voltage was 5 kV and the magnification was 2000 times. It was confirmed by observation that the nonwoven fabric was deposited in a fibrous form, not in a droplet form, within the field of view. Those that were deposited in a fibrous form were considered to be acceptable. Furthermore, the number of beads was counted, and those with less than 50 were considered to be acceptable.

[0197] The composition prepared in (1) was left to stand at room temperature for another month, and then a nonwoven fabric was prepared again by the method described in (1), and the number of beads was counted in the same manner. The results are shown in Tables 1 to 3.

[0198] (3) Measurement of fiber diameter The nonwoven fabric obtained by electrospinning was sputtered with gold and observed under a scanning electron microscope (SEM). The accelerating voltage was 5 kV and the magnification was 10,000 times. 30 fibers were randomly selected within the field of view, and their widths were measured. The arithmetic mean was calculated to determine the fiber diameter. The results are shown in Tables 1 to 3.

[0199] (4) Method for measuring the tensile strength of nonwoven fabrics implementation Example 1 3~15, 18, 21, 23, 25, 28 and 32 , Reference Examples 2, 3 and 7,The strength of the nonwoven fabric was measured in Comparative Examples 1, 3, 5, 7, 9, 11, 13, and 15. Note that, since Examples 2 and 6 consisted of precursor polymer solutions, an inert oven (CLH-21CD-S; manufactured by Koyo Thermo Systems Co., Ltd.) was used to heat the nonwoven fabric at an oxygen concentration of 20 ppm or less, raising the temperature to 280°C at a rate of 5°C / min, and then the nonwoven fabric was heat-treated at 280°C for 1 hour, followed by cooling to 50°C at a rate of 5°C / min, before the following measurements were carried out.

[0200] (1) In the same manner as above, remove the residual solvent ( Reference Examples 2 and 3 The nonwoven fabric that had been subjected to the process up to (for example, the subsequent heat treatment) was separated from the aluminum foil and its thickness was measured with a micrometer. By adjusting the electrospinning time, a nonwoven fabric with a thickness of 20 μm was produced.

[0201] This nonwoven fabric was cut into strips 1 cm wide and approximately 5 cm long to serve as specimens for strength measurement. Tensilon (RTM-100; manufactured by Orientec) was used to measure the tensile strength, and the average of the top five measurements was calculated as the tensile strength. The results are shown in Tables 1 to 3. <Tensile strength measurement conditions> Temperature: 23℃ Humidity: 45%RH Load full scale: 25N Crosshead speed: 50mm / min Break detection sensitivity: 1.0%.

[0202] (5) Measurement of the 5% weight loss temperature of the resin The polymer solutions of Synthesis Examples 1 to 23 were spin-coated onto an 8-inch silicon wafer and then baked for 3 minutes on a hot plate (Coating and Developing Apparatus Act-8; manufactured by Tokyo Electron Ltd.) at 120° C. to obtain a resin film.

[0203] This resin film was heated in an inert oven (CLH-21CD-S; manufactured by Koyo Thermo Systems Co., Ltd.) at an oxygen concentration of 20 ppm or less. (A) Synthesis Examples 2, 4, 8, 10 to 13, and 17 Heat up to 280°C at 5°C / min and heat at 280°C for 1 hour (B) Synthesis Examples 3, 5, 6, 7, 9, 14 to 16, and 18 to 23 Heat up to 150°C at 5°C / min and heat at 150°C for 1 hour After this, the substrate was cooled to 50°C at a rate of 5°C / min. The film was then immersed in hydrofluoric acid for 1 to 4 minutes to peel it off from the substrate, and air-dried to obtain a heat-treated coating. The rotation speed during spin coating was adjusted so that the resin film thickness after heat treatment would be 10 μm. The film thickness was measured using an optical interference film thickness measuring device (Lambda Ace STM-602; manufactured by Dainippon Screen Mfg. Co., Ltd.).

[0204] The coating was placed in a thermogravimetric analyzer (TGA-50; manufactured by Shimadzu Corporation) and heated to 150°C at a rate of 10°C / min to remove the adsorbed water. The temperature was then lowered to room temperature and the weight W1 was measured. The resin was then heated again at a rate of 10°C / min. The temperature at which the weight W2 of the resin during heating reached W2 / W1 = 0.95 was defined as the 5% weight loss temperature. The results are shown in Table 4.

[0205] [Table 1]

[0206] [Table 2]

[0207] [Table 3]

[0208] [Table 4]

Claims

1. A resin composition for forming a nonwoven fabric by electrospinning, comprising: (a) at least one heat-resistant resin or a precursor thereof selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having a group in the main chain selected from the group consisting of ether groups, ketone groups, sulfone groups, and sulfide groups; (b) a solvent; and (c) a surfactant having a fluoroalkyl group, wherein the surfactant having a fluoroalkyl group has at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen.

2. 2. The resin composition according to claim 1, wherein the surfactant (c) having a fluoroalkyl group is a compound having a group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a hydroxyl group, or an alkali metal salt or alkaline earth metal salt thereof.

3. The resin composition according to claim 1 or 2, wherein the surfactant (c) having a fluoroalkyl group does not have a structure in which repeating units containing a fluoroalkyl group are linked together.

4. 4. The resin composition according to claim 1, wherein the heat-resistant resin of component (a) is a resin selected from the group consisting of polyimide, polyamideimide, polyamide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyurea, polyether ketone, polyether ether ketone, polyether sulfone, and polyphenylene sulfide.

5. The resin composition according to any one of claims 1 to 4, wherein the heat-resistant resin of the component (a) has a structure represented by at least one selected from the following general formulas (1) to (5): 【Chemistry 1】 (In general formula (1), R １ represents a divalent group having 2 to 50 carbon atoms. ２ represents a tetravalent group having 4 to 50 carbon atoms. １ represents an integer from 1 to 10,000. 【Chemistry 2】 (In general formula (2), R ３ represents a divalent group having 2 to 50 carbon atoms. ４ represents a trivalent group having 4 to 50 carbon atoms. ２ represents an integer from 1 to 10,000. 【Transformation 3】 (In general formula (3), R ５ represents a divalent group having 2 to 50 carbon atoms. ６ represents a divalent group having 2 to 50 carbon atoms. ３ represents an integer from 1 to 10,000. 【Chemistry 4】 (In general formula (4), R ７ represents a divalent group having 2 to 50 carbon atoms. ８ represents a divalent group having 2 to 50 carbon atoms. ４ represents an integer from 1 to 10,000. 【Transformation 5】 (In general formula (5), R ９ represents a divalent group having 2 to 50 carbon atoms. １０ represents a tetravalent group having 4 to 50 carbon atoms. X represents a divalent group selected from -O-, -S-, -NH-, and -C(=O)O-. m ５ represents an integer from 1 to 10,000.

6. R in general formula (1) １ , R in general formula (2) ３ , R in general formula (3) ５ , R in general formula (3) ６ , R in general formula (4) ７ , R in general formula (4) ８ and R in general formula (5) ９ The resin composition according to claim 5, wherein 30 mol % or more of the above-mentioned formulas have a structure represented by the following general formula (6) or (7): 【Transformation 6】 (In general formula (6), R １１ represents a monovalent group having 1 to 6 carbon atoms, and is located in the ortho position relative to the polymer main chain. １ represents an integer of 1 to 4.) 【Transformation 7】 (In general formula (7), R １２ and R １３ each independently represents a monovalent group having 1 to 6 carbon atoms, and is located in the ortho position relative to the polymer main chain. ２ and n ３ each independently represents an integer of 1 to 4. ２ is a single bond, -O-, -S-, -CH ２ -, -C(CH ３ ) ２ -, -C(CF ３ ) ２ represents at least one selected from

7. A nonwoven fabric comprising: (a) at least one heat-resistant resin or a precursor thereof selected from the group consisting of heat-resistant resins containing nitrogen atoms and heat-resistant resins having a group in the main chain selected from the group consisting of an ether group, a ketone group, a sulfone group, and a sulfide group; and (c) a surfactant having a fluoroalkyl group, wherein the surfactant having a fluoroalkyl group has at least one group selected from an oxyethylene group, an oxypropylene group, and a group containing quaternary nitrogen.

8. 8. The nonwoven fabric according to claim 7, wherein (c) the surfactant having a fluoroalkyl group is a compound having a group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a hydroxyl group, or an alkali metal salt or alkaline earth metal salt thereof.

9. 9. The nonwoven fabric according to claim 7, wherein the surfactant (c) having a fluoroalkyl group does not have a structure in which repeating units containing a fluoroalkyl group are linked together.

10. 10. The nonwoven fabric according to claim 7, wherein the heat-resistant resin of component (a) is a resin selected from the group consisting of polyimide, polyamideimide, polyamide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyurea, polyether ketone, polyether ether ketone, polyether sulfone, and polyphenylene sulfide.

11. 11. The nonwoven fabric according to claim 7, wherein the heat-resistant resin of component (a) has a structure represented by at least one selected from the following general formulas (1) to (5): 【Transformation 8】 (In general formula (1), R １ represents a divalent group having 2 to 50 carbon atoms. ２ represents a tetravalent group having 4 to 50 carbon atoms. １ represents an integer from 1 to 10,000) 【Chemistry 9】 (In general formula (2), R ３ represents a divalent group having 2 to 50 carbon atoms. ４ represents a trivalent group having 4 to 50 carbon atoms. ２ represents an integer from 1 to 10,000) 【Chemistry 10】 (In general formula (3), R ５ represents a divalent group having 2 to 50 carbon atoms. ６ represents a divalent group having 2 to 50 carbon atoms. ３ represents an integer from 1 to 10,000) 【Chemistry 11】 (In general formula (4), R ７ represents a divalent group having 2 to 50 carbon atoms. ８ represents a divalent group having 2 to 50 carbon atoms. ４ represents an integer from 1 to 10,000) 【Chemistry 12】 (In general formula (5), R ９ represents a divalent group having 2 to 50 carbon atoms. １０ represents a tetravalent group having 4 to 50 carbon atoms. X represents a divalent group selected from -O-, -S-, -NH-, and -C(=O)O-. m ５ represents an integer from 1 to 10,000)

12. R in general formula (1) １ , R in general formula (2) ３ , R in general formula (3) ５ , R in general formula (3) ６ , R in general formula (4) ７ , R in general formula (4) ８ and R in general formula (5) ９ The nonwoven fabric according to claim 11, wherein 30 mol % or more of the above-mentioned formulas have a structure represented by the following general formula (6) or (7): 【Chemistry 13】 (In general formula (6), R １１ represents a monovalent group having 1 to 6 carbon atoms, and is located in the ortho position relative to the polymer main chain. １ represents an integer of 1 to 4.) 【Chemistry 14】 (In general formula (7), R １２ and R １３ each independently represents a monovalent group having 1 to 6 carbon atoms, and is located in the ortho position relative to the polymer main chain. ２ and n ３ each independently represents an integer of 1 to 4. ２ is a single bond, -O-, -S-, -CH ２ -, -C(CH ３ ) ２ -, -C(CF ３ ) ２ represents at least one selected from

13. A method for producing a nonwoven fabric, comprising electrospinning a resin composition according to any one of claims 1 to 6 to form a nonwoven fabric.

14. A textile product comprising the nonwoven fabric according to any one of claims 7 to 12.

15. A separator for an electric storage element, comprising the nonwoven fabric according to any one of claims 7 to 12.

16. A secondary battery comprising the separator according to claim 15.

17. An electric double layer capacitor comprising the separator according to claim 15.

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