Organic solvent solution of styrenesulfonate and method for producing the same, and use thereof

Abstract

To provide a method that markedly enhances solubility of ammonium styrenesulfonate in organic solvents, which has been a conventional issue, and thus allows use of ammonium styrenesulfonate in polymer substrate modification employing graft polymerization and in manufacture of electrolyte membranes, which were previously difficult.SOLUTION: Solubility of ammonium styrenesulfonate is increased by adding a specific base when preparing an organic solvent solution of ammonium styrenesulfonate. In one aspect, an organic solvent solution of styrenesulfonate includes an organic solvent, ammonium styrenesulfonate, and a base in an amount of 10.0 mol% to 120.0 mol% relative to ammonium styrenesulfonate, wherein the concentration of styrenesulfonate at 25°C, in terms of ammonium styrenesulfonate, is 9.0 wt.% to 45.0 wt.% relative to the total amount of the solution.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an organic solvent solution of a styrene sulfonate salt, a method for producing the same, and uses thereof. [Background technology]

[0002] Styrene sulfonate or its polymer is a strong acid-type water-soluble monomer or polymer that has excellent heat resistance and chemical stability. It has long been used as a reactive emulsifier or dispersant, and is also used as a raw material for graft-modifying polymer substrates and as a raw material for cation exchange membranes.

[0003] Among styrene sulfonates, sodium styrene sulfonate (hereinafter abbreviated as NaSS) is widely used industrially, but its applications are limited due to its poor solubility in organic solvents and the inclusion of an alkali metal. For example, a method for imparting functions such as hydrophilicity, antifouling properties, proton conductivity, and ion exchange capacity to a hydrophobic polymer substrate such as polyolefin involves graft polymerization of a strong acid vinyl monomer or polymer onto the substrate (e.g., Non-Patent Document 1, Patent Document 1, etc.). However, because NaSS dissolves only in water or specific aprotic polar organic solvents, graft polymerization onto the above-mentioned hydrophobic polymer substrates is considered difficult (for example, Patent Document 2, Non-Patent Document 2, etc.). This is because NaSS, which is too hydrophilic, is unlikely to come into contact at the molecular level with radicals present on the surface of the hydrophobic polymer.

[0004] Therefore, in order to graft polymerize NaSS, methods such as first graft polymerizing amphiphilic acrylic acid and then graft polymerizing NaSS, or graft polymerization using a water / methanol solution of NaSS have been investigated, but the grafting efficiency of NaSS remains insufficient (e.g., Non-Patent Document 1, Patent Document 2, etc.). Another known method involves graft polymerizing an oil-soluble styrene sulfonate ester derived from styrene sulfonate using an organic solvent solution, followed by hydrolysis of the sulfonate ester group to convert it to a sulfo group (e.g., Patent Documents 3 to 5, etc.). Another known method involves graft polymerizing an oil-soluble 2-propanol solution of α-methylstyrene and methacrylonitrile, followed by sulfonation of the graft polymer chain (e.g., Patent Document 5).

[0005] However, styrene sulfonate esters have issues with their manufacturing process and the resulting high costs, preventing their mass production. Furthermore, after graft polymerization of styrene sulfonate esters, an additional step is required, such as alkaline hydrolysis of the ester groups. Furthermore, the method of graft copolymerizing α-methylstyrene and methacrylonitrile followed by sulfonation requires toxic and dangerous raw materials, such as halogenated solvents and sulfonating agents, and generates large amounts of waste liquid.

[0006] Another known styrene sulfonate is lithium styrene sulfonate (hereinafter abbreviated as LiSS). Although it is an alkali metal salt, it dissolves in polar organic solvents such as N-methylpyrrolidone, and it is known that by copolymerizing it with an oil-soluble cross-linkable vinyl monomer such as divinylbenzene, electrolyte membranes such as cation exchange membranes can be easily produced (see, for example, Patent Document 7). However, LiSS has not yet been mass-produced due to the high raw material cost and issues with the manufacturing process.

[0007] Furthermore, because styrene sulfonate has a strong acidic group and a high carbon density, it is expected to be used as a raw material for photoresist polymers in addition to the above applications (for example, Patent Documents 8 to 10). The polymer is applied to a semiconductor substrate as a solution, and propylene glycol monomethyl ether or propylene glycol monomethyl ether acetate is preferably used as the organic solvent. These solvents are used in the process of producing the polymer or in the process of producing a solution of the obtained polymer, but styrene sulfonate is insoluble in these solvents and therefore cannot be used directly as is.

[0008] In light of the above-mentioned background, there has been a strong demand for an organic solvent solution of a styrene sulfonate that is mass-producible and inexpensive, and that is useful for the graft modification of polymer substrates and the production of electrolyte membranes and various polymers. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 7292742 [Patent Document 2] Japanese Patent Application Publication No. 2017-186712 [Patent Document 3] Patent No. 6663647 [Patent Document 4] Patent No. 5836028 [Patent Document 5] Patent No. 5314148 [Patent Document 6] Patent No. 4664609 [Patent Document 7] Patent No. 7386705 [Patent Document 8] International Publication No. WO2014 / 109186 [Patent Document 9] Patent No. 5382321 [Patent Document 10] International Publication No. WO2023 / 017728 [Patent Document 11] Japanese Patent Application Laid-Open No. 2008-248181 [Non-patent literature]

[0010] [Non-Patent Document 1] Kyoichi Saito, Revolutionizing Polymer Adsorbents through Graft Polymerization, pp. 8-10, Maruzen Publishing, 2014 [Non-patent document 2] NHV Corporation website: https: / / www.nhv.jp / blog / post723 / ("Electron Beam Graft Polymerization Part 2: Factors Affecting Graft Polymerization") [Non-patent document 3] Oriental Soda Research Report, Vol. 24, No. 1, 1980, pp. 3-11 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above background and problems, and an object of the present invention is to provide an organic solvent solution containing a styrene sulfonate and a simple method for producing the same. The present invention also provides a method for producing a graft-modified polymer substrate using the organic solvent solution containing the styrene sulfonate, and a method for producing an electrolyte membrane. [Means for solving the problem]

[0012] The present inventors conducted a detailed study of the solubility of ammonium styrenesulfonate (AmSS) in organic solvents and found that the solubility of AmSS in a specific organic solvent can be significantly increased by adding a specific base, which led to the completion of the present invention.

[0013] That is, the present invention relates to the following inventions. [1] an organic solvent; Ammonium styrene sulfonate, 10.0 mol % to 120.0 mol % of a base relative to ammonium styrenesulfonate; An organic solvent solution of styrene sulfonate comprising: A solution of styrene sulfonate in an organic solvent, wherein the concentration of the styrene sulfonate at 25°C is 9.0% by weight to 45.0% by weight, calculated as ammonium styrene sulfonate, relative to the total amount of the solution. [2] The solution of item [1], wherein 80% by weight or more of the organic solvent is one or more organic solvents selected from the group consisting of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, acetone, methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, propylene glycol monomethyl ether, dioxane, tetrahydrofuran, acetonitrile, 2-butanone, ethyl acetate, and toluene. [3] The organic solvent solution of item [2], wherein the organic solvent is one or more selected from the group consisting of acetone, methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, propylene glycol monomethyl ether, dioxane, and tetrahydrofuran. [4] The organic solvent solution according to item [1], wherein the base is at least one selected from the group consisting of amines, lithium hydroxide, and tetraalkylammonium hydroxide. [5] The organic solvent solution according to item [4], wherein the amines are aliphatic amines having 9 or less carbon atoms. [6] The organic solvent solution according to item [4], wherein the amines are one or more selected from the group consisting of 1-azabicyclo[2.2.2.]octane, 2-amino-2-methyl-1-propanol, ethylamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]-5-nonene, diisopropanolamine, diethanolisopropanolamine, diethylamine, diethanolamine, diethanolisopropanolamine, N,N-diethylethanolamine, 2-[(2-dimethylamino)ethoxy]ethanol, N,N-dimethylethanolamine, N,N-dimethylcyclohexylamine, triethylamine, 2-hydroxyethylamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, and monoisopropanolamine. [7] Put the organic solvent into the container. To this, ammonium styrenesulfonate and 10.0 mol % to 120.0 mol % of a base relative to the ammonium styrenesulfonate are added, Stir to dissolve, or Put ammonium styrene sulfonate into a container, To this, 10.0 mol % to 120.0 mol % of a base relative to ammonium styrenesulfonate is added, and then Add organic solvent, Stir to dissolve, A method for producing a styrene sulfonate organic solvent solution. [8] A method for producing a graft-modified polymer substrate, comprising: bringing a polymer substrate, on the surface of which radicals have been generated by irradiation, into contact with an organic solvent solution of the styrene sulfonate salt according to any one of items [1] to [6], and polymerizing the polymer substrate. [9] A monomer solution containing an organic solvent solution of the styrene sulfonate salt according to any one of items [1] to [6], a crosslinkable monomer, and a polymerization initiator, Coating or impregnation onto a support and polymerizing; A method for manufacturing an electrolyte membrane. [Effects of the Invention]

[0014] According to the present invention, by adding a specific base when dissolving ammonium styrenesulfonate in a specific organic solvent, the solubility of ammonium styrenesulfonate in the organic solvent can be significantly increased, and therefore it is possible to provide an organic solvent solution containing a high concentration of styrenesulfonate, which has been difficult to achieve in the past, and a method for producing the same. Furthermore, the present invention makes it possible to apply ammonium styrenesulfonate in the modification of hydrophobic polymer substrates and the production of electrolyte membranes by graft polymerization, which has been difficult to do in the past due to its insufficient solubility in organic solvents. [Brief explanation of the drawings]

[0015] [Figure 1] This figure shows the relationship between the amount of base added to the acetone solution of AmSS described in Example 1 and the AmSS-equivalent concentration of the supernatant. The horizontal axis represents the mole percentage of N,N-dimethylcyclohexylamine (indicated as DMCHA in the figure) relative to AmSS, and the vertical axis represents the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt%) in acetone at 25°C. [Figure 2] This figure shows the relationship between the amount of base added to the acetone solution of AmSS described in Example 2 and the AmSS-equivalent concentration of the supernatant, with the horizontal axis representing the mole percent of N,N-dimethyl-2-ethanolamine (represented as DMAE in the figure) relative to AmSS, and the vertical axis representing the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt% (weight %)) in acetone at 25°C. In the figure, the values ​​indicated by circles (●) represent the solubility at 25°C, and the values ​​indicated by triangles (▲) represent the solubility at 40°C. [Figure 3] This figure shows the relationship between the amount of base added and the AmSS-equivalent concentration of the supernatant in the propylene glycol monomethyl ether solution of AmSS described in Example 3. The horizontal axis represents the mole percent of N,N-dimethylaminoethanol (indicated as DMAE in the figure) relative to AmSS, and the vertical axis represents the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt% (weight %)) in propylene glycol monomethyl ether at 25°C. In the figure, the values ​​indicated by circles (●) represent the solubility at 25°C, and the values ​​indicated by triangles (▲) represent the solubility at 40°C. [Figure 4]This figure shows the relationship between the amount of base added to the N-methylpyrrolidone solution of AmSS described in Example 4 and the AmSS-equivalent concentration of the supernatant, with the horizontal axis representing the mole percent of lithium hydroxide monohydrate (denoted as LiOH in the figure) relative to AmSS, and the vertical axis representing the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt% (weight %)) in N-methylpyrrolidone at 25°C. In the figure, the values ​​indicated by circles (●) represent the solubility at 25°C, and the values ​​indicated by triangles (▲) represent the solubility at 40°C. [Figure 5] This figure shows the relationship between the amount of base added to the ethanol solution of AmSS described in Example 5 and the AmSS-equivalent concentration of the supernatant. The horizontal axis represents the mole percent of lithium hydroxide monohydrate (indicated as LiOH in the figure) relative to AmSS, and the vertical axis represents the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt%) in ethanol at 25°C. [Figure 6] This figure shows the relationship between the amount of base added to the acetone solution of AmSS described in Example 6 and the AmSS-equivalent concentration of the supernatant. The horizontal axis represents the mole percent of triethylamine (indicated as TEA in the figure) relative to AmSS, and the vertical axis represents the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt% (weight %)) in acetone at 25°C. [Figure 7] This figure shows the relationship between the amount of base added to the methanol solution of AmSS described in Example 7 and the AmSS-equivalent concentration of the supernatant. The horizontal axis represents the mole percent of N,N-dimethyl-2-ethanolamine (indicated as DMAE in the figure) relative to AmSS, and the vertical axis represents the AmSS-equivalent concentration of the supernatant, i.e., the solubility (wt%) in methanol at 25°C. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below. The organic solvent solution containing a styrene sulfonate of the present invention contains a specific organic solvent, ammonium styrene sulfonate, and a specific base as shown below.

[0017] Known styrene sulfonates include sodium styrene sulfonate (hereinafter abbreviated as NaSS), lithium styrene sulfonate (hereinafter abbreviated as LiSS), and ammonium styrene sulfonate (hereinafter abbreviated as AmSS) (see, for example, Non-Patent Document 3). Of these, only NaSS is mass-produced and widely used. However, it has problems such as poor solubility, particularly in organic solvents, and a high concentration of alkali metals.

[0018] LiSS has far superior solubility to NaSS in certain solvents, such as N-methylpyrrolidone, and is therefore used as a raw material for electrolyte membranes, such as the cation exchange membranes mentioned above. However, the high cost of the raw materials and manufacturing process has hindered market expansion. Furthermore, the types of solvents in which LiSS can dissolve are limited, and it has not been used for the graft modification of polymer substrates mentioned above.

[0019] However, AmSS has significant issues with its manufacturing method and storage stability, preventing its commercialization. However, the inventors continued to study the physical properties of AmSS and manufacturing methods suitable for mass production, and discovered an inexpensive method for manufacturing AmSS with good storage stability. A detailed investigation of the solubility of AmSS anhydrous with improved storage stability revealed that, like LiSS, it is soluble in highly polar, high-boiling organic solvents such as N-methylpyrrolidone, but its solubility is not necessarily sufficient for producing dense electrolyte membranes. Furthermore, it is practically insoluble in other organic solvents with relatively low boiling points.

[0020] As mentioned above, when graft polymerizing styrene sulfonate or a monomer or polymer convertible to styrene sulfonate onto a hydrophobic polymer substrate, an organic solvent solution of the monomer or polymer is used. The organic solvent used in the solution is an inexpensive organic solvent with a relatively low boiling point and good wettability with the hydrophobic polymer, such as acetone, methanol, ethanol, propanol, dioxane, acetate, or toluene (see, for example, Patent Document 1 and Patent Documents 3 to 5). As mentioned above, propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate, which are less harmful, are preferably used as organic solvents for producing polymer solutions for photoresists. However, AmSS has poor solubility, particularly in acetone, ethanol, propanol, dioxane, toluene, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate, making it difficult to apply it to the above-mentioned uses.

[0021] The present inventors therefore investigated methods for dissolving AmSS in organic solvents at as high a concentration as possible and found that the solubility of AmSS can be significantly increased by adding a specific base when preparing an AmSS solution using an organic solvent.

[0022] The organic solvent used in the present invention is an organic solvent that is preferably used in the above-mentioned applications, and is one or more organic solvents selected from the group consisting of aprotic polar solvents such as N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and 1,3-dimethyl-2-imidazolidinone; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, and 1-methoxy-2-propanol; ethers such as propylene glycol monomethyl ether, dioxane, tetrahydrofuran, and dihydrolevoglucosenone; ketones such as acetone and 2-butanone; acetate esters such as methyl acetate, ethyl acetate, and propyl acetate; acetonitrile; and toluene. In the solution containing the organic solvent of the present invention, it is preferable that 80% by weight or more of the total amount of the organic solvent is the above-mentioned organic solvent.

[0023] Among these, in consideration of the applicability to the above-mentioned uses, the removability after use, the recyclability of the solvent, and the like, solvents having a relatively low boiling point and viscosity are preferred, and for example, acetone, methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, propylene glycol monomethyl ether, dioxane, tetrahydrofuran, and toluene are preferred.

[0024] The organic solvent may contain less than 20% by weight of a solvent other than those mentioned above in order to further increase the solubility of AmSS or to dissolve a comonomer or the like.

[0025] The solvent other than those mentioned above is not particularly limited as long as it dissolves in the AmSS solution, and may include, for example, water, alcohol-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, aliphatic hydrocarbon-based solvents, and aromatic hydrocarbon-based solvents. However, an increase in the proportion of water may decrease the grafting efficiency of AmSS or the solubility of comonomers and AmSS copolymers, so the proportion of water is preferably 10% by weight or less, and more preferably 5% by weight or less.

[0026] The specific base is one that dissolves or disperses in an organic solvent solution of AmSS, and more specifically, is a base such as an amine, lithium hydroxide, or tetraalkylammonium hydroxide. Examples of amines include 1-azabicyclo[2.2.2.]octane, 2-amino-2-methyl-1-propanol, ethylamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]-5-nonene, diisopropanolamine, diethanolisopropanolamine, diethylamine, diethanolamine, diethanolisopropanolamine, N,N-diethyl-2-hydroxyethylamine, 2-[(2-dimethylamino)ethoxy]ethanol, N,N-dimethyl-2-hydroxyethylamine, N,N -dimethylcyclohexylamine, 2,2'-dimorpholinodiethyl ether, triethylamine, triethanolamine, triethylenediamine, 2-hydroxyethylamine, piperidine, bis(2-dimethylaminoethyl)ether, N-methylethanolamine, N-methyl-N,N-diethanolamine, N-methylpiperazine, N-methylpiperidine, N-methylmorpholine, morpholine, monoisopropanolamine, tris(2-ethylhexyl)amine, monooctylamine, dilauryl monomethylamine, and trioctylamine.

[0027] Among these, aliphatic amines having 9 or less carbon atoms are preferred in consideration of the coloring of the organic solvent solution of AmSS and the effect of improving solubility per added weight. Among aliphatic amines having 9 or less carbon atoms, amines having an acid dissociation constant pKa of more than 9.25 are more preferred in consideration of the effect of improving solubility per added weight, such as 1-azabicyclo[2.2.2.]octane, 2-amino-2-methyl-1-propanol, ethylamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]- Examples of such an amine include 5-nonene, diisopropanolamine, diethanolisopropanolamine, diethylamine, diethanolamine, diethanolisopropanolamine, N,N-diethylethanolamine, 2-[(2-dimethylamino)ethoxy]ethanol, N,N-dimethylethanolamine, N,N-dimethylcyclohexylamine, triethylamine, 2-hydroxyethylamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, and monoisopropanolamine. Examples of lithium hydroxide include anhydrous lithium hydroxide and lithium hydroxide monohydrate, and examples of tetraalkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0028] The amount of base added to AmSS is 10.0 mol% to 120.0 mol%, and generally, the more moles added, the higher the solubility, but if the amount is too high, the salting-out effect may actually decrease the solubility. Also, considering the safety and odor of the AmSS organic solvent solution, the smaller the excess amount of base, the better, so 20.0 mol% to 110.0 mol%, and more preferably 20.0 mol% to 100.0 mol%, is preferred. The appropriate amount of base to add varies depending on the strength of the base, molecular weight, valence, solubility, or dispersibility, making it difficult to generalize. However, the amount can be determined based on the intended use. For example, adding 1 mole of base to 1 mole of AmSS is 100 mole %. The solubility of AmSS in acetone at 25°C is 0.03 wt% (weight %), but depending on the type and amount of base added, the concentration in AmSS terms can increase to over 35 wt%.

[0029] For example, if a certain amount of N,N-dimethyl-2-ethanolamine is added to a slurry consisting of AmSS and an organic solvent at a concentration exceeding the solubility limit and stirred, AmSS gradually dissolves to form a clear solution. This is thought to be because the undissolved AmSS is converted to the N,N-dimethyl-2-ethanolamine salt of styrenesulfonic acid. Therefore, the ammonium salt of styrenesulfonic acid and the N,N-dimethyl-2-ethanolamine salt coexist in the organic solvent solution as an equilibrium mixture, and their ratio changes depending on the amount of N,N-dimethyl-2-ethanolamine added. The above-mentioned concentration in terms of AmSS means a concentration in which all of these styrene sulfonates are regarded as AmSS (molecular weight 201.25 g / mol).

[0030] The base is contained in an amount of 10.0 mol % to 120.0 mol % based on AmSS, etc. The concentration of styrene sulfonate in the organic solvent solution at 25°C is 9.0 wt % to 45.0 wt % in terms of AmSS based on the total amount of the organic solvent solution. When preparing an organic solvent solution of AmSS, the method for dissolving AmSS is not particularly limited.

[0031] Furthermore, the method for producing the ammonium styrenesulfonate organic solvent solution of the present invention includes the following steps: A method in which an organic solvent is placed in a suitable reactor, dissolution tank, or other container, and ammonium styrenesulfonate and a base in an amount of 10.0 mol% to 120.0 mol% relative to the ammonium styrenesulfonate are added, stirred, and dissolved. Or, Ammonium styrene sulfonate is placed in a suitable reactor or dissolution tank, and a base is added in an amount of 10.0 mol% to 120.0 mol% based on the ammonium styrene sulfonate. An organic solvent is then added, and the mixture is stirred and dissolved. Examples include:

[0032] The dissolution temperature can be room temperature, but heating can be used to shorten the dissolution time. Taking into consideration the natural polymerization of AmSS (also known as spontaneous polymerization or catalyst-free polymerization), the temperature is usually between 0°C and 60°C. When dissolving by heating or storing for a long period of time, air can be introduced or a small amount of polymerization inhibitor can be added to prevent natural polymerization.

[0033] Furthermore, when preparing or after preparing an organic solvent solution of AmSS, if additives such as a polymerization inhibitor, a chain transfer agent, a monomer other than AmSS, and a polymerization initiator, which will be described below, are added, a solvent other than the above may be added to dissolve them. There are no particular limitations on the solvent, as long as it does not interfere with the dissolution of AmSS and the above additives.

[0034] There are no limitations on the polymerization inhibitor as long as it dissolves in the organic solvent solution of AmSS and inhibits polymerization, and examples of the polymerization inhibitor that can be used include phenol-based polymerization inhibitors, stable nitroxyl radicals, and phenothiazine.

[0035] Examples of phenol-based polymerization inhibitors include 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-ethylphenol, 4-sec-butyl-2,6-di-tert-butylphenol, 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, and 2,5-dimethoxyphenol. , 2,6-dimethoxyphenol, 4-tert-butylcatechol, hydroquinone, methylhydroquinone, 2-methoxyhydroquinone, 4,4'-methylenebis(2,6-di-tert-butylphenol), 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene, 2,2',6,6'-tetra-tert-butyl-4,4'-dihydroxybiphenyl, methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3-(3,5-di-tert-butyl-4 -hydroxyphenyl)octadecylpropionate, 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide, bis[3-(3,5-di-tert- Examples of stable nitroxyl radicals include 2,2,6,6-tetramethylpiperidine 1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl.Examples include 6-tetramethylpiperidine 1-oxyl, 4-(2-hydroxypropoxy-3-(2-hydroxyethoxy))-2,2,6,6-tetramethylpiperidin-1-ol, and 4-(3-hydroxypropoxy-2-(2-hydroxyethoxy))-2,2,6,6-tetramethylpiperidin-1-ol.

[0036] In addition to the above, bromine compounds such as lithium bromide, sodium bromide, and ammonium bromide, which have a polymerization inhibitory effect on styrene sulfonate, albeit weakly, can be used.

[0037] The amount to be added varies depending on the strength of the effect of the polymerization inhibitor and cannot be generalized, but is usually 1.0 mol% or less based on AmSS. Taking into consideration the inhibition of polymerization during graft polymerization and polymer production, the amount is preferably 0.20 mol% or less, and more preferably 0.10 mol%.

[0038] The organic solvent solution of AmSS obtained by the above method has a high concentration and is useful for the modification of polymer substrates using graft polymerization methods and for the production of electrolyte membranes such as cation exchange membranes.

[0039] The graft-modified polymer of the present invention can be produced by some known methods, such as irradiating the polymer substrate with radiation such as alpha rays, beta rays, gamma rays, electron beams, or ultraviolet rays, or by subjecting the polymer substrate to plasma treatment or corona discharge treatment to generate radicals on the polymer surface, and then contacting the polymer with an organic solvent solution of deoxygenated AmSS for polymerization (see, for example, Patent Documents 1 to 4 and 11).

[0040] The polymer substrate may be a film, porous hollow fiber membrane, porous sheet, fiber, nonwoven fabric, particle, or the like, made of polyolefin, fluorinated polyolefin, polyester, polyamide, or aromatic engineering plastic, without any particular limitation. For example, after irradiating the polymer substrate with gamma rays under an inert gas atmosphere, the substrate is immersed in a previously degassed organic solvent solution of AmSS to graft polymerize AmSS at a predetermined temperature for a predetermined time. The polymer substrate is then removed and washed with an organic solvent or water, allowing for the simple introduction of sulfo groups into the polymer substrate. This eliminates the need for a hydrolysis step (also called a deprotection step) such as alkali treatment, which is required when using sulfonic acid esters.

[0041] The electrolyte membrane of the present invention can be produced by coating or impregnating a support with a monomer solution containing the above-mentioned AmSS in an organic solvent, a crosslinkable monomer, and a polymerization initiator for radical polymerization, etc. Other known methods can also be used for some of the electrolyte membrane production methods (see, for example, Patent Document 7).

[0042] For example, an electrolyte membrane can be easily produced by adding an oil-soluble crosslinkable monomer such as divinylbenzene and an oil-soluble polymerization initiator such as an azo compound, an organic peroxide, or a photoinitiator to an organic solvent solution of AmSS to prepare a curable composition, applying the composition to a support or impregnating a porous support with the composition, and then subjecting the composition to radical polymerization while heating or irradiating with radiation.

[0043] Any support may be used as long as it is suitable for the purpose of the present invention, including, for example, paper, nonwoven fabric, plastics such as polyolefins and aromatic polyamides, and porous inorganic materials, which can be polymerized after being coated or impregnated with a composition containing an AmSS organic solvent solution, a crosslinking agent, and an initiator.

[0044] During polymerization such as radical polymerization, chain transfer agents (also called molecular weight regulators) can be added to suppress rapid and uneven polymerization reactions and to adjust the length of the polymer chains.

[0045] The chain transfer agent is not particularly limited as long as it is soluble in the monomer solution, and examples thereof include thioglycolic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, thiomalonic acid, dithiosuccinic acid, thiomaleic acid, thiomaleic anhydride, dithiomaleic acid, thioglutaric acid, cysteine, homocysteine, 5-mercaptotetrazoleacetic acid, 3-mercapto-1-propanesulfonic acid, 3-mercaptopropane-1 ,2-diol, mercaptoethanol, 1,2-dimethylmercaptoethane, 2-mercaptoethylamine hydrochloride, 6-mercapto-1-hexanol, 2-mercapto-1-imidazole, 3-mercapto-1,2,4-triazole, mercaptans such as cysteine, N-acylcysteine, glutathione, N-butylaminoethanethiol, N,N-diethylaminoethanethiol, diisopropyl xanthogen disulfide, diethyl xanthogen disulfide, diethylthiuram disulfide, 2,2 Disulfides such as '-dithiodipropionic acid, 3,3'-dithiodipropionic acid, 4,4'-dithiodibutanoic acid, and 2,2'-dithiobisbenzoic acid, halogenated hydrocarbons such as iodoform, benzyl dithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, 4-cyano-4-(thiobenzoylthio)pentanoic acid, 4-cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanoic acid, S,S-dibenzyltrithiocarbonate, 3-((((1-carboxyethyl)thio)carbonate Examples of suitable iodide compounds include thiocarbonylthio compounds such as thioyl)thio)propanoic acid and cyanomethyl (3,5-dimethyl-1H-pyrazole)carbodithioate, α-iodobenzyl cyanide, 1-iodoethylbenzene, ethyl 2-iodo-2-phenylacetate, 2-iodo-2-phenylacetic acid, 2-iodopropanoic acid, and 2-iodoacetic acid, as well as alkyl iodides such as diphenylethylene, p-chlorodiphenylethylene, p-cyanodiphenylethylene, α-methylstyrene dimer, organotellurium compounds, and sulfur.

[0046] Furthermore, when graft polymerizing AmSS, a comonomer can be added to perform graft copolymerization. There are no particular limitations on the comonomer, so long as it is copolymerizable with AmSS and soluble in an organic solvent solution of AmSS. Examples of the comonomer include styrene-based monomers, acrylic acid ester-based monomers, methacrylic acid-based monomers, acrylamide-based monomers, methacrylamide-based monomers, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, maleic acid, maleic anhydride, itaconic acid, maleimides, N-vinylpyrrolidone, vinyl chloride, and vinylidene chloride.

[0047] Typical applications of the organic solvent solution of styrene sulfonate obtained by the present invention include electrolyte membranes such as the above-mentioned cation exchange membranes and fuel cell membranes, graft polymerization modification of various substrates, and photoresist polymers. In addition to the applications of graft polymerization modification described above in Non-Patent Document 1, Patent Documents 1 and 11, it is expected to be used as sulfonated polymer fibers for electrochemical CO reduction (for example, JP 2023-114444 A). Additionally, for example, an organic solvent solution of styrenesulfonic acid amine salt or lithium salt can be easily obtained by adding and dissolving ammonium styrenesulfonate and a base in an amount of 100 mol% relative to the ammonium styrenesulfonate in a specific organic solvent, and then distilling off the ammonia under reduced pressure. Amine salts of styrenesulfonate are useful as raw materials for polymer-type antistatic agents, etc. (for example, JP 8-104787 A), and lithium styrenesulfonate is useful as a raw material for components for lithium secondary batteries (JP 2024-3753 A, JP 2020-514961 A, JP 2022-16033 A, Japanese Patent No. 6195153 A). [Example]

[0048] The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

[0049] <Medications used> AmSS: Ammonium styrenesulfonate (manufactured by Tosoh Finechem Corporation, purity 97.5% by weight, moisture content 0.28% by weight) N-Methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Corporation, ultra-dehydrated grade, moisture content 10 ppm or less) Acetone (manufactured by Fujifilm Wako Pure Chemical Corporation, ultra-dehydrated grade, moisture content 10 ppm or less) Methanol (manufactured by Fujifilm Wako Pure Chemical Corporation, ultra-dehydrated grade, moisture content 10 ppm or less) Ethanol (manufactured by Fujifilm Wako Pure Chemical Corporation, ultra-dehydrated grade, moisture content 10 ppm or less) Propylene glycol monomethyl ether (manufactured by Fujifilm Wako Pure Chemical Corporation) N,N-Dimethyl-2-hydroxyethylamine (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 99.0%) N,N-Dimethylcyclohexylamine (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 98.0%) Triethylamine (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 99.0%) 4-Methylmorpholine (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 99.0%) Lithium hydroxide monohydrate (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 98.0%) Triethanolamine (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade) Sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade) Lithium chloride (manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, purity ≥ 99.0%)

[0050] <Preparation and Concentration Measurement of AmSS Organic Solvent Solution> AmSS, base, and organic solvent were collected in a 50 ml glass bottle, sealed, and stirred with a magnetic stirrer for 60 minutes at 25°C to obtain a slurry. The bottle was then left to stand at 25°C for 60 minutes to allow excess AmSS crystals to settle, after which the supernatant was collected with a syringe equipped with a membrane filter (DSMIC (registered trademark) 13HP045AN, manufactured by Advantec Toyo Co., Ltd.), diluted with the GPC eluent described below, and subjected to gel permeation chromatography (GPC) measurement to calculate the AmSS concentration (i.e., solubility) of the supernatant. Solutions with different AmSS concentrations were prepared, and a calibration curve was created from the area of ​​the peak whose peak top elution time was 14.8 minutes, with AmSS concentration (ppm) on the horizontal axis and AmSS peak area (mV·sec) on the vertical axis. The AmSS concentration in the sample solution was calculated from the area of ​​the peak that appeared at 14.8 minutes in the above sample solution. The peak area was calculated using the built-in GPC system. The GPC measurement conditions are as follows: Equipment: Tosoh Corporation HLC-8320 Column: TSKgel® guard column AW-H / TSKgel® AW-6000 / TSKgel® AW-3000 / TSKgel® AW-2500 Eluent: 0.05M aqueous sodium sulfate / acetonitrile = 65 / 35 (volume ratio) solution Flow rate, injection volume, column temperature: 0.6 ml / min, injection volume: 10 μl, column temperature: 40°C Detector: UV detector (wavelength 230 nm) Calibration curve: The following calibration curve was obtained under the above conditions. AmSS concentration (ppm) = 0.0972 × AmSS peak area (mV sec) Although the slope of the calibration curve, 0.0972, was obtained under the above conditions, it is not guaranteed to be the same value and may vary due to errors, the AmSS concentration range in the calibration curve, the intensity measured by the detector, or other parameters not specified in the above conditions. For this reason, it is best to use the calibration curve within the applicable range when measuring the target AmSS.

[0051] Example 1 AmSS (6.01 g, 29.12 mmol), N,N-dimethylcyclohexylamine (1.00 g, 7.86 mmol, pKa = 10.00, hereafter abbreviated as DMCHA), and ultra-dehydrated acetone (9.17 g) were placed in a 50 mL glass vial, sealed, and stirred for 60 minutes at a predetermined temperature using a magnetic stirrer. The resulting slurry had an AmSS concentration of 36.22 wt%. The vial was then left to stand at a predetermined temperature for 60 minutes to allow excess undissolved AmSS crystals to settle. The supernatant (1.1700 g) was collected using a syringe equipped with a membrane filter (DSMIC® 13HP045AN, manufactured by Advantec Toyo Co., Ltd.) and diluted with the GPC eluent (weight of the diluted solution: 40.6908 g). 2.4881 g of the diluted supernatant was collected and further diluted again with the eluent (weight of the diluted solution: 19.5101 g, total dilution ratio: 272.71 times), and then subjected to gel permeation chromatography (GPC) measurement. The concentration (i.e., solubility) of AmSS in the supernatant (before dilution) was calculated from the area of ​​the peak that appeared at an elution time of 14.8 minutes (4858.84 mV·sec) using the following formula (1). AmSS concentration (ppm) = Peak area (mV·sec) × Slope of calibration curve (ppm / mV·sec) × Total dilution factor (1) That is, by applying equation (1), the AmSS concentration is 4858.84 (mV·sec) × 0.0972 (ppm / (mV·sec)) × 272.71 = 128795 (ppm), which converts to 12.9 wt%. Similarly, the AmSS concentration in the supernatant was measured by varying the amounts of AmSS, DMCHA, and acetone collected. The relationship between the mole percentage of DMCHA relative to AmSS and the AmSS concentration at 25°C is shown in Table 1 and Figure 1. It is clear that the addition of DMCHA significantly increased the solubility of AmSS. From the above results, for example, when AmSS (3.00 g, 14.53 mmol) and DMCHA (1.00 g, 7.78 mmol, 53.5 mol% relative to AmSS) are mixed in acetone (11.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 19.50 wt% and a DMCHA concentration of 6.53 wt%. Taking into account the water content in AmSS, the composition of the organic solvent is acetone / water = 99.9 / 0.1 (based on weight percentage (wt%)).

[0052] Example 2 An acetone solution of AmSS was prepared in the same manner as in Example 1, except that the base DMCHA in Example 1 was changed to N,N-dimethyl-2-hydroxyethylamine (pKa = 9.31, hereinafter abbreviated as DMAE), and the concentration of AmSS in the supernatant was measured. The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 2. It is clear that the addition of DMAE significantly increased the solubility of AmSS. Furthermore, the solubility increased with increasing temperature. From the above results, for example, when AmSS (3.00 g) and DMAE (1.25 g) are mixed in acetone (6.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 28.54 wt% and a DMAE concentration of 12.07 wt% (95.52 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is acetone / water = 99.9 / 0.1 (based on weight percentage (wt%)).

[0053] Example 3 In Example 2, a PGME solution of AmSS was prepared in the same manner as in Example 1, except that the organic solvent was changed to propylene glycol monomethyl ether (hereinafter abbreviated as PGME), and the concentration of AmSS in the supernatant was measured. The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 3. It is clear that the addition of DMAE significantly increased the solubility of AmSS. From the above results, for example, when AmSS (1.00 g) and DMAE (0.42 g) are mixed in PGME (9.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 9.36 wt% and a DMAE concentration of 3.99 wt% (96.28 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is PGME / water = 99.97 / 0.03 (based on weight percentage (wt%)).

[0054] Example 4 An AmSS NMP solution was prepared in the same manner as in Example 1, except that the base DMCHA in Example 1 was changed to lithium hydroxide monohydrate (pKa = 14) and the organic solvent was changed to N-methylpyrrolidone (hereinafter abbreviated as NMP), and the AmSS concentration of the supernatant was measured. The relationship between the mole percent of LiOH relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 4. It is clear that the addition of LiOH significantly increased the solubility of AmSS. Lithium hydroxide monohydrate is insoluble in NMP, but it dissolved in the presence of AmSS, suggesting that cation exchange occurred in the NMP solution. Furthermore, compared to the acetone solution in Example 2, almost no temperature dependence of solubility was observed. From the above results, for example, when AmSS (3.00 g) and lithium hydroxide monohydrate (0.60 g) are mixed in NMP (5.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 34.01 wt% and a lithium hydroxide concentration of 3.90 wt% (96.42 mol% relative to AmSS). Taking into account the water content of AmSS and lithium hydroxide monohydrate, the composition of the organic solvent is NMP / water = 95.05 / 4.95 (based on weight % (wt%)).

[0055] Example 5 In Example 4, an ethanol solution of AmSS was prepared in the same manner as in Example 1, except that the organic solvent was changed to ethanol, and the AmSS concentration of the supernatant was measured. The relationship between the mole percent of LiOH relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 5. It is clear that the addition of LiOH significantly increased the solubility of AmSS. From the above results, for example, when AmSS (3.00 g) and lithium hydroxide monohydrate (0.60 g) are mixed in ethanol (10.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 21.51 wt% and a lithium hydroxide concentration of 2.47 wt% (96.42 mol% relative to AmSS). Taking into account the water content of AmSS and lithium hydroxide monohydrate, the composition of the organic solvent is ethanol / water = 97.46 / 2.54 (weight % (wt%) basis).

[0056] Example 6 An acetone solution of AmSS was prepared in the same manner as in Example 1, except that the base DMCHA in Example 1 was changed to triethylamine (pKa = 10.7, hereinafter abbreviated as TEA), and the concentration of the supernatant was measured. The relationship between the mole percent of TEA relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 6. It is clear that the addition of TEA significantly increased the solubility of AmSS. From the above results, for example, when AmSS (3.00 g) and TEA (1.40 g) are mixed in acetone (6.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 28.13 wt% and a TEA concentration of 13.33 wt% (94.24 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is acetone / water = 99.86 / 0.14 (based on weight % (wt%)).

[0057] Example 7 A methanol solution of AmSS was prepared in the same manner as in Example 1, except that the base DMCHA was changed to N,N-dimethyl-2-hydroxyethylamine (pKa = 9.31, hereinafter abbreviated as DMAE) and the organic solvent was changed to methanol, and the concentration of AmSS in the supernatant was measured. The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 7. It is clear that the addition of DMAE significantly increased the solubility of AmSS. From the above results, for example, when AmSS (3.00 g) and DMAE (1.30 g) are mixed in methanol (12.00 g) at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 17.94 wt% and a DMAE concentration of 7.90 wt% (99.34 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is acetone / water = 99.93 / 0.07 (based on weight % (wt%)).

[0058] Example 8 An AmSS solution was prepared in the same manner as in Example 7, except that methanol containing 11% by weight of water was used as the organic solvent, and the AmSS concentration of the supernatant was measured. The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration is shown in Table 2. It is clear that the addition of DMAE increased the solubility of AmSS. From the above results, for example, when AmSS (2.00 g) and DMAE (0.85 g) are mixed in methanol (7.00 g) containing 11 wt% water at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 19.80 wt% and a DMAE concentration of 8.54 wt% (98.41 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is methanol / water = 88.48 / 11.52 (based on weight % (wt%)).

[0059] Example 9 An AmSS solution was prepared in the same manner as in Example 2, except that acetone containing 17% by weight of water was used as the organic solvent, and the AmSS concentration of the supernatant was measured. The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration is shown in Table 2. It is clear that the addition of DMAE significantly increased the solubility of AmSS. From the above results, for example, when AmSS (2.00 g) and DMAE (0.85 g) are mixed in acetone (6.00 g) containing 17 wt% water at 25°C, they gradually dissolve, eventually forming a solution with an AmSS concentration of 22.03 wt% and a DMAE concentration of 9.51 wt% (98.41 mol% relative to AmSS). Taking into account the water content in AmSS, the composition of the organic solvent is acetone / water = 83.19 / 16.81 (based on weight % (wt%)).

[0060] [Table 1]

[0061] [Table 2]

[0062] Comparative Example 1 An acetone solution of AmSS was prepared in the same manner as in Example 1, except that the base DMCHA in Example 1 was changed to triethanolamine (pKa=7.77, hereinafter abbreviated as TEAOH), and the concentration of the supernatant was measured. The relationship between the mole percentage of TEAOH relative to AmSS and the AmSS concentration is shown in Table 3. The addition of TEAOH did not increase the solubility of AmSS. The main reason for this is thought to be that the pKa of TEAOH is too low.

[0063] Comparative Example 2 An acetone solution of AmSS was prepared in the same manner as in Example 1, except that the base DMCHA in Example 1 was changed to 4-methylmorpholine (pKa = 7.38, hereinafter abbreviated as M-MOR), and the concentration of the supernatant was measured. The relationship between the mole percentage of M-MOR relative to AmSS and the AmSS concentration is shown in Table 3. The addition of M-MOR did not significantly increase the solubility of AmSS, which is thought to be mainly due to the low pKa of M-MOR.

[0064] Comparative Example 3 An acetone solution of AmSS was prepared in the same manner as in Example 5, except that the base lithium hydroxide in Example 5 was changed to sodium ethoxide (pKa = 16, hereinafter abbreviated as EtONa), and the concentration of the supernatant was measured. The relationship between the mole percent of EtONa relative to AmSS and the AmSS concentration is shown in Table 3. The addition of EtONa actually decreased the solubility of AmSS. Although the reason for this is unclear, it is clear that not only the pKa of the base but also its type is important for increasing the solubility of AmSS.

[0065] Comparative Example 4 An acetone solution of AmSS was prepared in the same manner as in Example 5, except that the base lithium hydroxide in Example 5 was changed to lithium bromide (pKa = 2.64, hereinafter abbreviated as LiBr), and the concentration of the supernatant was measured. The relationship between the mole percent of LiBr relative to AmSS and the AmSS concentration is shown in Table 3. Addition of LiBr did not increase the solubility of AmSS. This is thought to be because the pKa of LiBr is too small and LiBr simply acts as a salting-out agent.

[0066] [Table 3] [Industrial Applicability]

[0067] The solubility of AmSS in organic solvents, which was previously a problem, can be significantly increased, making it possible to apply AmSS to the modification of hydrophobic polymer substrates by graft polymerization and the production of cation exchange membranes, which was previously difficult.

Claims

1. an organic solvent; Ammonium styrene sulfonate, 10.0 mol % to 120.0 mol % of a base relative to ammonium styrenesulfonate; An organic solvent solution of styrene sulfonate comprising: A solution of styrene sulfonate in an organic solvent, wherein the concentration of the styrene sulfonate at 25°C is 9.0% by weight to 45.0% by weight, calculated as ammonium styrene sulfonate, relative to the total amount of the solution.

2. 2. The organic solvent solution according to claim 1, wherein 80% by weight or more of the organic solvent is one or more organic solvents selected from the group consisting of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, acetone, methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, propylene glycol monomethyl ether, dioxane, tetrahydrofuran, 2-butanone, ethyl acetate, and toluene.

3. 3. The organic solvent solution according to claim 2, wherein the organic solvent is at least one selected from the group consisting of acetone, methanol, ethanol, 1-propanol, 2-propanol, methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, propylene glycol monomethyl ether, dioxane, tetrahydrofuran, and toluene.

4. 2. The organic solvent solution according to claim 1, wherein the base is at least one selected from the group consisting of amines, lithium hydroxide, and tetraalkylammonium hydroxide.

5. The organic solvent solution according to claim 4 , wherein the amine is an aliphatic amine having 9 or less carbon atoms.

6. The organic solvent solution according to claim 4, wherein the amine is at least one selected from the group consisting of 1-azabicyclo[2.2.2]octane, 2-amino-2-methyl-1-propanol, ethylamine, 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]-5-nonene, diisopropanolamine, diethanolisopropanolamine, diethylamine, diethanolamine, diethanolisopropanolamine, N,N-diethylethanolamine, 2-[(2-dimethylamino)ethoxy]ethanol, N,N-dimethylethanolamine, N,N-dimethylcyclohexylamine, triethylamine, 2-hydroxyethylamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, and monoisopropanolamine.

7. Put the organic solvent into the container. To this, ammonium styrenesulfonate and 10.0 mol % to 120.0 mol % of a base relative to the ammonium styrenesulfonate are added, Stir to dissolve, or Put ammonium styrene sulfonate into a container, To this, 10.0 mol % to 120.0 mol % of a base relative to ammonium styrenesulfonate is added, and then Add organic solvent, Stir to dissolve, A method for producing a styrene sulfonate organic solvent solution.

8. A method for producing a graft-modified polymer substrate, comprising: irradiating a polymer substrate on the surface of which radicals have been generated, and contacting the polymer substrate with an organic solvent solution of the styrene sulfonate salt according to any one of claims 1 to 6, thereby polymerizing the polymer substrate.

9. a monomer solution containing an organic solvent solution of the styrene sulfonate salt according to any one of claims 1 to 6, a crosslinkable monomer, and a polymerization initiator; Coating or impregnation onto a support and polymerizing; A method for manufacturing an electrolyte membrane.

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