High-concentration aqueous styrene sulfonic acid ammonium solution composition, method for producing the same, and use thereof

Abstract

To provide a high-concentration aqueous styrene sulfonic acid ammonium solution composition and a method for producing the same.SOLUTION: There is provided a high-concentration aqueous styrene sulfonic acid ammonium solution composition, which is an aqueous styrene sulfonate solution composition comprising water, styrene sulfonic acid ammonium, and a base in an amount of 10.0 mol% to 120.0 mol% relative to the styrene sulfonic acid ammonium, wherein the concentration of the styrene sulfonate at 25°C, in terms of styrene sulfonic acid ammonium, is 30.0 wt.% to 60.0 wt.% based on the total amount of the aqueous solution, the base being preferably at least one selected from the group consisting of amines, lithium hydroxide, and tetraalkylammonium hydroxides, and more preferably an aliphatic amine having 9 or fewer carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a highly concentrated aqueous ammonium styrenesulfonate composition, a method for producing the same, and uses thereof. [Background technology]

[0002] Styrene sulfonate is a surface-active strong acid salt type anionic monomer that has excellent heat resistance and radical polymerization properties. It is used as a reactive emulsifier for emulsion polymerization, and has long been used as a raw material for producing aqueous dispersants, aqueous detergents, and dopants for conductive polymers. Sodium styrene sulfonate (hereinafter abbreviated as NaSS) is the most widely used industrially, but its applications are limited due to its poor solubility in various solvents and the inclusion of alkali metals.

[0003] Given the above background, alkali-metal-free ammonium styrenesulfonate (hereinafter abbreviated as AmSS) has long attracted attention (e.g., Non-Patent Document 1), but significant issues with its production method and storage stability prevented its industrialization. The present inventors then continued to study the physical properties and production method of AmSS, and discovered an inexpensive method for producing AmSS with good storage stability. Detailed investigation of the physical properties of AmSS anhydrous salt with improved storage stability revealed that its solubility in certain polar organic solvents, such as N-methylpyrrolidone and dimethyl sulfoxide, is much higher than that of NaSS. However, as described in Non-Patent Document 1, it was confirmed that its solubility in water is not significantly different from that of NaSS.

[0004] Meanwhile, a method for producing a cation exchange membrane using an aqueous solution of an anionic monomer is known, and since no organic solvent is required, it has the advantage of being environmentally friendly (e.g., Patent Document 1 and Patent Document 2). This method allows a cation exchange membrane to be easily produced by coating or impregnating a support with an aqueous solution containing an anionic monomer, a crosslinkable monomer, and a photopolymerization initiator, followed by polymerization; however, a highly concentrated aqueous monomer solution is required to obtain a dense membrane (e.g., paragraph 0030 of Patent Document 1 and paragraph 0063 of Patent Document 2).

[0005] However, since AmSS has insufficient solubility in water, its application to the cation exchange membrane manufacturing process is difficult, and there has been a strong demand for a method for dissolving AmSS in water at as high a concentration as possible. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2023-519746 [Patent Document 2] Special Publication No. 2022-502522 [Non-patent literature]

[0007] [Non-Patent Document 1] Oriental Soda Research Report, Vol. 24, No. 1, 1980, pp. 3-11 Summary of the Invention [Problem to be solved by the invention]

[0008] 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 aqueous solution composition containing a high concentration of styrene sulfonate and a method for producing the same. Another object of the present invention is to provide a method for producing a cation exchange membrane, in particular a dense cation exchange membrane, using the high concentration aqueous solution of styrene sulfonate. [Means for solving the problem]

[0009] The present inventors conducted a detailed study of the solubility of ammonium styrenesulfonate (AmSS) in water and found that the addition of a specific base when dissolving AmSS significantly increases its solubility in water, leading to the completion of the present invention.

[0010] That is, the present invention relates to the following inventions. [1] Water and Ammonium styrene sulfonate, A styrene sulfonate aqueous solution composition comprising 10.0 mol % to 120.0 mol % of a base relative to ammonium styrene sulfonate, A high-concentration aqueous ammonium styrenesulfonate solution composition, in which the concentration of styrenesulfonate at 25°C is 30.0% by weight to 60.0% by weight, calculated as ammonium styrenesulfonate, based on the total amount of the aqueous solution. [2] The aqueous solution according to item [1], wherein the base is at least one selected from the group consisting of amines, lithium hydroxide, and tetraalkylammonium hydroxide. [3] The aqueous solution according to item [2], wherein the amines are aliphatic amines having 9 or less carbon atoms. [4] The aqueous solution according to [2], wherein the amines are one or more amines 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. [5] Put water 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 water and Stir to dissolve, A method for producing a high-concentration ammonium styrenesulfonate aqueous solution composition according to item [1]. [6] An aqueous solution composition of high-concentration ammonium styrenesulfonate according to any one of items [1] to [4], a crosslinkable monomer, and A monomer solution containing a polymerization initiator is applied to or impregnated into a support, and polymerized. Method for manufacturing a cation exchange membrane. [Effects of the Invention]

[0011] According to the present invention, the solubility of ammonium styrenesulfonate in water can be significantly increased by adding a specific base, and therefore it is possible to provide an aqueous solution composition 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 to a cation exchange membrane production process that requires a highly concentrated aqueous monomer solution, which has been difficult to do in the past, and provides an environmentally friendly method for producing a cation exchange membrane based on styrenesulfonic acid that does not use organic solvents. [Brief explanation of the drawings]

[0012] [Figure 1] This figure shows the temperature dependence of the solubility of AmSS measured in Reference Example 1. The horizontal axis represents temperature (°C) and the vertical axis represents the solubility of AmSS (wt%, weight %). In the figure, the values ​​indicated by triangles (▲) are data obtained in Reference Example 1, and the values ​​indicated by circles (◯) are data described in Non-Patent Document 1. [Figure 2]This figure shows the relationship between the amount of base added and the solubility of AmSS in Example 1. The horizontal axis represents the mole percent of N,N-dimethylaminoethanol (DMAE) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%). 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] The graph shows the temperature dependence of AmSS solubility. The horizontal axis is temperature (°C) and the vertical axis is AmSS solubility (wt%). In the graph, the triangles indicate the solubility of AmSS without the addition of base, and the circles indicate the solubility of AmSS with the addition of 39.6 mol% N,N-dimethylaminoethanol (DMAE). [Figure 4] This shows the relationship between the amount of base added and the solubility of AmSS in Example 2. The horizontal axis represents the mole percent of N,N-dimethylcyclohexylamine (indicated as DMCHA in the figure) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%) at 25°C. [Figure 5] This figure shows the relationship between the amount of base added and the concentration of the AmSS aqueous solution in Example 3. The horizontal axis represents the mole percent of lithium hydroxide monohydrate (LiOH) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%). 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 6] This shows the relationship between the amount of base added and the concentration of the AmSS aqueous solution in Example 4. The horizontal axis represents the mole percent of triethylamine (denoted as TEA in the figure) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%, weight %) at 25°C. [Figure 7] 1 shows the relationship between the amount of base added and the concentration of the AmSS aqueous solution in Comparative Example 1, with the horizontal axis representing the mole percent of triethanolamine (shown as TEAOH in the figure) relative to AmSS, and the vertical axis representing the solubility of AmSS at 25°C. [Figure 8]This shows the relationship between the amount of base added and the concentration of the AmSS aqueous solution in Comparative Example 2. The horizontal axis represents the mole percent of sodium hydroxide (shown as NaOH in the figure) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%, weight %) at 25°C. [Figure 9] This shows the relationship between the amount of lithium chloride added and the concentration of the AmSS aqueous solution in Comparative Example 3. The horizontal axis represents the mole percent of lithium chloride (shown as LiCl in the figure) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%, weight %) at 25°C. [Figure 10] This figure shows the relationship between the amount of 4-methylmorpholine added and the concentration of the AmSS aqueous solution in Comparative Example 4. The horizontal axis represents the mole percent of 4-methylmorpholine (indicated as M-MOR in the figure) relative to AmSS, and the vertical axis represents the solubility of AmSS (wt%, weight %) at 25°C. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below.

[0014] The highly concentrated aqueous styrene sulfonate solution composition of the present invention contains water, ammonium styrene sulfonate, and a specific base as shown below. The base is contained in an amount of 10.0 mol % to 120.0 mol % based on ammonium styrenesulfonate. The concentration of styrenesulfonate in the aqueous solution at 25°C is 30.0 wt % to 60.0 wt % based on the total amount of the aqueous solution, calculated as ammonium styrenesulfonate.

[0015] Furthermore, the method for producing the aqueous solution composition of the present invention containing ammonium styrenesulfonate at a high concentration comprises the steps of: A method in which water is placed in a suitable reactor, dissolution tank, or other container, and ammonium styrene sulfonate and a base in an amount of 10.0 mol% to 120.0 mol% relative to the ammonium styrene sulfonate are added, followed by stirring to dissolve. Or, Place ammonium styrenesulfonate in a suitable reactor or dissolution tank, add 10.0 mol% to 120.0 mol% of a base based on the ammonium styrenesulfonate, add water, and dissolve by stirring. Examples include:

[0016] Here, styrene sulfonate is an anionic monomer having surface activity, and known examples include sodium styrene sulfonate (NaSS), lithium styrene sulfonate (hereinafter abbreviated as LiSS), and ammonium styrene sulfonate (AmSS).

[0017] Of these, only NaSS is mass-produced and widely used. Although NaSS has an extremely high thermal decomposition temperature, it has the drawback of having low solubility in various solvents and containing a high concentration of alkali metals.

[0018] LiSS has better solubility than NaSS and the same high thermal decomposition temperature as NaSS, but its applications are limited due to its high cost and high alkali metal content. In addition, LiSS has high raw material costs and manufacturing process issues, preventing it from being mass-produced.

[0019] Ammonium styrenesulfonate (AmSS) has serious problems with its manufacturing method and storage stability, preventing its commercialization. However, the present inventors have continued to study the physical properties and manufacturing method of AmSS and have discovered an inexpensive method for manufacturing AmSS with good storage stability. Detailed investigation of the physical properties of AmSS anhydrous salt with improved storage stability revealed that its solubility in certain polar organic solvents, such as N-methylpyrrolidone and dimethyl sulfoxide, is much higher than that of NaSS. However, as described in Non-Patent Document 1 above, it was confirmed that its solubility in water is not significantly different from that of NaSS.

[0020] One application of styrene sulfonate is the production of cation exchange membranes. For example, cation exchange membranes can be easily produced by coating or impregnating a support with a monomer solution containing an anionic monomer, a crosslinkable monomer, and a radical polymerization initiator, followed by polymerization (see, for example, Patent Documents 1, 2, and Japanese Patent Publication No. 5924282). To obtain a dense cation exchange membrane, a highly concentrated monomer solution is required. However, aqueous solutions are becoming the trend for monomer solutions due to environmental considerations. Although a highly concentrated aqueous monomer solution is required, AmSS has low solubility in water, making it difficult to apply AmSS to the cation exchange membrane production process.

[0021] The present inventors therefore investigated methods for dissolving AmSS in water 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 aqueous solution of AmSS.

[0022] The specific base is one that dissolves in an aqueous solution of AmSS, and more specifically, is a base such as amines, lithium hydroxide, tetraalkylammonium hydroxide, etc. These bases may be added alone or in combination.

[0023] Among the amines, taking into consideration the coloring of the AmSS aqueous solution and the effect of improving solubility per added weight, aliphatic amines having 9 or less carbon atoms are preferred, 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]-5-nonene, diisopropanolamine, diethanolisopropanolamine, diethylamine, diethanolamine, diethanolisopropanolamine, N,N-diethyl-2-hydroxyethylamine, Examples include 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, and monoisopropanolamine. Among the aliphatic amines having 9 or less carbon atoms, amines having an acid dissociation constant pKa of greater than 9.25 are more preferred in terms of the effect of improving solubility per added weight. Examples thereof 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-diethylethanolamine, 2-[(2-dimethylamino)ethoxy]ethanol, N,N-dimethylethanolamine, N,N-dimethylcyclohexylamine, triethylamine, 2-hydroxyethylamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, and monoisopropanolamine.

[0024] 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.

[0025] The amount of base added to AmSS is 10.0 mol% to 120.0 mol%, and although the solubility generally increases with increasing molar addition, too much base may actually decrease the solubility due to the salting-out effect. Also, considering the safety and odor of the AmSS aqueous solution, a small excess of base is preferable, so 20.0 mol% to 110.0 mol%, and more preferably 20.0 mol% to 100.0 mol%, is preferred.

[0026] The appropriate amount of base to add varies depending on the strength of the base, molecular weight, valence, water solubility, etc., so the amount can be determined based on the intended use. For example, if 1 mole of base is added to 1 mole of AmSS, the ratio is 100 mole %. The solubility of AmSS in water at 25°C is 26.2 wt% (weight %), but depending on the type and amount of base added, the concentration in AmSS terms can increase to over 50 wt%.

[0027] For example, when a certain amount of N,N-dimethyl-2-ethanolamine is added to a slurry consisting of AmSS and water at a concentration exceeding the saturated concentration, AmSS dissolves and a clear aqueous solution is formed. 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 aqueous 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).

[0028] When producing an aqueous solution composition containing a high concentration of AmSS, there is no particular limitation on the method for dissolving AmSS. A method in which water is placed in a suitable reactor or 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 thereto, followed by stirring to dissolve the mixture; or A method in which ammonium styrenesulfonate 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 styrenesulfonate, followed by adding water and stirring to dissolve. Examples include: There are no particular limitations on the container as long as it is capable of producing an aqueous solution composition containing a high concentration of AmSS, and the size, capacity, shape, etc. of the container may be selected according to the purpose.

[0029] The dissolution temperature can be room temperature, but since it is endothermic, it can also be heated. Considering 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, oxygen or nitrogen monoxide can be introduced into the container space or a small amount of polymerization inhibitor can be added to prevent natural polymerization, but stirring and dissolving in the presence of air is the simplest method.

[0030] Furthermore, when additives such as a polymerization inhibitor, a chain transfer agent, a monomer other than AmSS, and a polymerization initiator described below are added during or after the preparation of the AmSS aqueous solution composition, a water-soluble solvent other than water may be added to dissolve these additives.

[0031] The water-soluble solvent is not particularly limited as long as it does not interfere with the dissolution of AmSS and the above-mentioned additives. Examples of the water-soluble solvent include alcohols such as methanol, ethanol, methoxyethanol, ethoxyethanol, propanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and ethylene glycol; ethers such as methoxyethanol, ethoxyethanol, 1-methoxy-2-propanol, 1,2-dimethoxypropane, propylene glycol monomethyl ether, tetrahydrofuran, dioxane, and dihydrolevoglucosenone; acetonitrile, acetone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and 1,3-dimethyl-2-imidazolidinone. These water-soluble solvents are merely auxiliary solvents, and are contained in an amount of 50% by weight or less of the total solvent, more preferably 20% by weight or less, and even more preferably 10% by weight or less.

[0032] There are no limitations on the polymerization inhibitor as long as it dissolves in the aqueous monomer solution and inhibits polymerization, and phenol-based polymerization inhibitors, stable nitroxyl radicals, etc. can be used. 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, and 3-ethoxyphenol. phenol, 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, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)- N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 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-butyl-4-hydroxyphenyl)propanoic acid][oxalylbis(azanediyl)]bis(ethane-2,1-diyl), tris(3,5-tert-butyl-4-hydroxybenzyl) isocyanurate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 2,2-thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate Examples of stable nitroxyl radicals include 2,2,6,6-tetramethylpiperidine 1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 4-(2-hydroxypropoxy-3-(2-hydroxyethoxy))-2,2,6,6-tetramethylpiperidin-1-ol, 4-(3-hydroxypropoxy-2-(2-hydroxyethoxy))-2,2,6,6-tetramethylpiperidin-1-ol, etc. In addition to the above, examples of bromine compounds that have a weak polymerization inhibitory effect on styrene sulfonate include lithium bromide, sodium bromide, and ammonium bromide. The amount to be added varies depending on the strength of the polymerization inhibitor, so it is difficult to generalize, but it is usually 1.0 mol% or less based on AmSS. Considering the inhibition of polymerization during the production of the ion exchange membrane, it is preferably 0.20 mol% or less, and more preferably 0.10 mol%.

[0033] The AmSS aqueous solution composition obtained by the above method contains AmSS at a high concentration, and is therefore particularly useful for producing a cation exchange membrane using environmentally friendly water as a solvent.

[0034] That is, the method for producing the cation exchange membrane of the present invention includes a method in which a support is coated or impregnated with an aqueous monomer solution containing the above-mentioned aqueous solution composition containing a high concentration of AmSS, a crosslinkable monomer, and a polymerization initiator such as an azo compound or an organic peroxide, and then polymerized.

[0035] In addition, known methods can be used as part of the method for producing the cation exchange membrane (see, for example, Patent Documents 1 and 2). For example, a curable composition can be prepared by adding a water-soluble crosslinkable monomer such as lithium divinylbenzenesulfonate or lithium bis-(4-styrenesulfonyl)imide and a water-soluble photopolymerization initiator such as fluorescein sodium salt to the AmSS aqueous solution, applying the curable composition to a support or impregnating a porous support with the curable composition, and then irradiating the composition with ultraviolet light to cause radical polymerization, thereby easily producing a cation exchange membrane.

[0036] Any support suitable for the purpose of the present invention can be used without limitation. For example, paper, nonwoven fabric, plastics such as aromatic polyamides and polyolefins, porous inorganic materials, etc. can be preferably used because they can be polymerized after coating or impregnation with a composition containing an aqueous solution containing a high concentration of AmSS, a crosslinking agent, and an initiator.

[0037] During the radical polymerization, a chain transfer agent (also called a molecular weight modifier) ​​can be added to suppress a rapid and non-uniform polymerization reaction and to increase the uniformity of the crosslinked structure.

[0038] 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.

[0039] The applications of the aqueous solution composition containing a high concentration of AmSS obtained by the present invention are not limited to the above-mentioned electrodialysis, water treatment, and cation exchange membranes for fuel cells. For example, it is expected to be used as a raw material for cation exchange membranes used in electrochemical CO2 reduction reactions (for example, JP 2023-29893 A and JP 2024-39016 A). Alternatively, for example, an aqueous solution of an amine salt or lithium salt of styrenesulfonate 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 water, and then distilling off the ammonia under reduced pressure.

[0040] Amine salts of styrenesulfonic acid are useful as raw materials for polymer-type antistatic agents and the like (for example, JP 2023-170327 A, JP 8-104787 A), and lithium styrenesulfonate is useful as a raw material for components for lithium secondary batteries (for example, JP 2024-3753 A, JP 2024-33219 A, JP 2020-514961 A, WO 2019 / 131347 A, Japanese Patent No. 6195153), components for plasma dicing of semiconductor substrates (for example, JP 2022-522345 A, Japanese Patent No. 7138297 A), components for optical films (for example, Japanese Patent No. 5970815 A). [Example]

[0041] 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.

[0042] <Medications used> AmSS: Ammonium styrenesulfonate (Tosoh Finechem Corporation, purity 97.5%) N,N-Dimethyl-2-hydroxyethylamine (Fujifilm Wako Pure Chemical Industries, Ltd., special grade, purity ≥ 99.0%) N,N-Dimethylcyclohexylamine (Fujifilm Wako Pure Chemical Industries, Ltd., 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%)

[0043] <Preparation and Concentration Measurement of AmSS Aqueous Solution> AmSS, a base, and ion-exchanged water were collected in a 50 ml glass standard bottle, sealed, and then stirred at 25°C for 60 minutes using a magnetic stirrer to obtain a slurry. Then, it was allowed to stand at 25°C for 60 minutes to precipitate excess AmSS crystals. After that, the supernatant was collected with a syringe equipped with a membrane filter [manufactured by Advantec Toyo Co., Ltd., DSMIC (registered trademark) 13HP045AN], diluted with the following GPC eluent, and the AmSS concentration (i.e., solubility) of the supernatant was calculated by gel permeation chromatography (GPC) measurement. Solutions with different AmSS concentrations were prepared, and a calibration curve consisting of the horizontal axis of AmSS concentration (ppm) and the vertical axis of AmSS peak area (mV·sec) was created from the peak area at an elution time of 14.8 minutes. 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 by the GPC built-in system.

[0044] The measurement conditions of GPC are as follows. Apparatus: HLC-8320 manufactured by Tosoh Corporation Column: TSKgel (registered trademark) guard column AW-H / TSKgel (registered trademark) AW-6000 / TSKgel (registered trademark) AW-3000 / TSKgel (registered trademark) AW-2500 Eluent: 0.05 M sodium sulfate aqueous solution / 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 determined 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.

[0045] Reference example 1 AmSS and ion-exchanged water were placed in a 50 ml glass bottle, sealed, and stirred for 60 minutes at a predetermined temperature using a magnetic stirrer. The bottle was then left to stand at 25°C for 60 minutes to allow excess undissolved AmSS crystals to settle. The supernatant was then collected using a syringe equipped with a membrane filter (DSMIC® 13HP045AN, manufactured by Advantec Toyo Co., Ltd.), diluted with the GPC eluent, and analyzed by gel permeation chromatography (GPC) to calculate the AmSS concentration (i.e., solubility) of the supernatant. The results are shown in Table 1 and Figure 1. Although the conditions for measuring AmSS solubility described in Non-Patent Document 1 are unknown, the data were almost identical to those described in Non-Patent Document 1.

[0046] [Table 1]

[0047] Example 1 AmSS (7.02 g, 34.01 mmol), N,N-dimethyl-2-hydroxyethylamine (1.20 g, 13.46 mmol, pKa = 9.31, hereafter abbreviated as DMAE), and ion-exchanged water (10.05 g) were placed in a 50 mL glass vial, sealed, and stirred for 60 minutes at a predetermined temperature using a magnetic stirrer. The AmSS concentration in the resulting slurry was 37.46 wt%. The solution was then allowed to stand at a predetermined temperature for 60 minutes to allow excess undissolved AmSS crystals to settle. The supernatant (0.4647 g) was then collected using a syringe equipped with a membrane filter (DSMIC® 13HP045AN, manufactured by Advantec Toyo Co., Ltd.) and diluted with the GPC eluent (the diluted solution weight was 37.3758 g). 2.14 g of the diluted supernatant was collected and further diluted again with the eluent (weight of the diluted solution: 16.009 g, total dilution ratio: 601.68 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 (5731.608 mV·sec) using the following formula (1). AmSS concentration = Peak area (mV·sec) × Slope of calibration curve × Total dilution factor (1) That is, by applying formula (1), the AmSS concentration is calculated as 5731.608×0.0972×601.68 / 10,000=33.52% by weight. Similarly, the AmSS concentration in the supernatant was measured while varying the amounts of AmSS, DMAE, and ion-exchanged water collected.

[0048] The relationship between the mole percent of DMAE relative to AmSS and the AmSS concentration at 25°C and 40°C is shown in Table 2 and Figure 2. It is clear that the addition of DMAE significantly increased the solubility of AmSS. The temperature dependence of AmSS solubility is shown in Figure 3. Normally, the solubility of AmSS in water increases with increasing temperature, and this was also the case when DMAE was added;

[0049] Example 2 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base DMAE in Example 1 was changed to N,N-dimethylcyclohexylamine (pKa = 10.0, hereinafter abbreviated as DMCHA), and the AmSS concentration of the supernatant was measured. The relationship between the mole % of DMCHA relative to AmSS and the AmSS concentration is shown in Table 1 and Figure 4. It is clear that the addition of DMCHA significantly increased the solubility of AmSS.

[0050] Example 3 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base DMAE in Example 1 was changed to lithium hydroxide monohydrate (pKa = 14), 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. Furthermore, as with DMAE, the solubility increased with increasing temperature.

[0051] [Table 2]

[0052] Example 4 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base in Example 1 was changed from DMAE 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.

[0053] Comparative Example 1 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base DMAE 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 2 and Figure 7. 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.

[0054] Comparative Example 2 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base in Example 1 was changed from DMAE to sodium hydroxide (pKa=14), and the concentration of the supernatant was measured. The relationship between the mole percent of NaOH relative to AmSS and the AmSS concentration is shown in Table 2 and Figure 8. Despite the large pKa, the solubility of AmSS did not increase, but rather decreased. The reason for this is unclear, but it is clear that not only the pKa of the base but also its type is important for increasing the solubility of AmSS.

[0055] Comparative Example 3 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base in Example 1 was changed from DMAE to lithium chloride (pKa=2.26), and the concentration of the supernatant was measured. The relationship between the mole percent of LiCl relative to AmSS and the AmSS concentration is shown in Table 2 and Figure 9. Addition of LiCl did not increase the solubility of AmSS. This is thought to be because the pKa of lithium chloride is too small, so lithium chloride simply acts as a salting-out agent.

[0056] Comparative Example 4 An AmSS aqueous solution was prepared in the same manner as in Example 1, except that the base DMAE 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 2 and Figure 10. The addition of M-MOR did not significantly increase the solubility of AmSS. This is thought to be mainly due to the low pKa of M-MOR.

[0057] [Table 3] [Industrial Applicability]

[0058] The solubility of AmSS in water, which was previously an issue, can be significantly increased, making it possible to apply AmSS to the cation exchange membrane manufacturing process using environmentally friendly water as a solvent, which was previously difficult.

Claims

1. Water and Ammonium styrene sulfonate, 10.0 mol % to 120.0 mol % of a base relative to ammonium styrenesulfonate, A high-concentration aqueous ammonium styrenesulfonate solution composition, wherein the concentration of styrenesulfonate at 25°C is 30.0% by weight to 60.0% by weight, calculated as ammonium styrenesulfonate, based on the total amount of the aqueous solution.

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

3. The aqueous solution composition according to claim 2 , wherein the amine is an aliphatic amine having 9 or less carbon atoms.

4. 3. The aqueous solution composition according to claim 2, wherein the amines are one or more amines 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.

5. Put water in a 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 water and Stir to dissolve, A method for producing the high-concentration aqueous ammonium styrenesulfonate composition according to claim 1.

6. A high-concentration aqueous solution of ammonium styrenesulfonate according to any one of claims 1 to 4, a crosslinkable monomer, and polymerization initiator a monomer solution containing Coating or impregnation onto a support and polymerizing; Method for manufacturing a cation exchange membrane.

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