Ammonium styrene sulfonate composition with excellent storage stability and production method therefor

Abstract

[Problem] To provide an ammonium styrene sulfonate composition with excellent long-term storage stability, and a simple and eco-friendly production method therefor. [Solution] An ammonium styrene sulfonate composition with characteristics (1)-(6) below. (1) The ammonium styrene sulfonate content in the composition is at least 88.0 weight%; (2) the water content in the composition is 10.00 weight% or less; (3) the alkali metal content in the composition is 0.50 weight% or less; (4) the halogen content in the composition is 1.00 weight% or less; (5) the polymer content in the composition is 0.20 weight% or less; and (6) the polymerization inhibitor content in the composition is 2000 ppm or less. A production method therefor is also used.

Description

Ammonium styrene sulfonate composition having excellent storage stability and method for producing the same

[0001] The present invention relates to an ammonium styrenesulfonate composition having excellent storage stability in which a decrease in purity and coloration due to spontaneous polymerization during long-term storage are suppressed, and to a simple method for producing the same.

[0002] Sodium styrenesulfonate is a strong electrolyte-type water-soluble monomer with surface activity, and is used in a wide range of industrial fields due to its excellent heat resistance and radical polymerizability.

[0003] For example, sodium styrene sulfonate has long been used as a reactive emulsifier in the production of acrylic emulsions for water-based paints and adhesives. When emulsion polymerizing radically polymerizable monomers such as acrylic esters and methacrylic esters, reducing the amount of conventional emulsifiers and instead adding a small amount of sodium styrene sulfonate for copolymerization improves the colloidal stability of the polymer emulsion and the water resistance and adhesion of the emulsion coating film. However, increasing the amount of sodium styrene sulfonate added to further improve colloidal stability can result in problems caused by sodium metal, such as reduced water resistance of the emulsion coating film and corrosion of iron nails used in wooden construction (see, for example, Non-Patent Document 1). Therefore, most anionic emulsifiers used in the production of acrylic emulsions are non-metallic ammonium salts (see, for example, Patent Documents 1 and 2). Furthermore, polysodium styrene sulfonate, a polymer of sodium styrene sulfonate, is used in electronic materials applications such as dispersants for carbon nanotubes, chemical mechanical polishing (CMP) slurries for semiconductor substrates, and post-polishing cleaners (see, for example, Patent Documents 3 to 5). However, particularly in semiconductor applications, metal and halogen components are a cause of defects and corrosion in the substrate, so it is desirable to minimize their content (see, for example, Patent Document 6). Therefore, ammonium salts of polystyrene sulfonic acid that contain as few metal and halogen components as possible are more preferred.

[0004] In light of the above-mentioned background, there is a strong market need for ammonium styrenesulfonate, and in order to meet this need, methods for producing it have been proposed (for example, Patent Documents 7 and 8, and Non-Patent Document 2).

[0005] In Patent Document 7, for example, sodium styrenesulfonate and ammonium sulfate are dissolved in methanol at 60°C to undergo a cation exchange reaction, followed by cooling to 30°C to precipitate sodium sulfate produced by cation exchange. The precipitated sodium sulfate is then filtered off to recover a methanol solution of ammonium styrenesulfonate, and the methanol solution is further concentrated to dryness to obtain ammonium styrenesulfonate solids. This method is described as utilizing the difference in solubility in methanol between ammonium styrenesulfonate produced by cation exchange and sodium sulfate. However, the total reaction substrate concentration is low at approximately 9 wt %, and the time required for concentration to dryness makes it easy for polymers to form during this time. Furthermore, the toxicity and flammability of methanol used as a reaction solvent pose safety issues. Furthermore, this method does not necessarily produce high-purity ammonium styrenesulfonate. The lower the dielectric constant of the solvent, the lower the degree of ionic dissociation of the salt. This makes it difficult for the cation exchange reaction to proceed in organic solvents. Furthermore, there is insufficient difference in the solubility of sodium styrenesulfonate and ammonium styrenesulfonate in organic solvents, resulting in the inevitable residual sodium in ammonium styrenesulfonate. Furthermore, commercially available sodium styrenesulfonate typically contains 2% to 3% by weight of sodium bromide as an impurity. However, sodium bromide and ammonium bromide produced by cation exchange between sodium bromide and ammonium sulfate dissolve in methanol, making it impossible to avoid the residual bromine in ammonium styrenesulfonate. Furthermore, the ammonium styrenesulfonate obtained by the above method has inferior storage stability compared to sodium styrenesulfonate, a more serious issue in industrialization. The lack of an appropriate polymerization inhibitor was thought to be the cause.

[0006] In Patent Document 8, for example, paratoluidine hydrochloride is added to an aqueous solution of sodium styrenesulfonate, and the toluidine styrenesulfonate salt precipitated by salt exchange is recovered. The toluidine salt is then introduced into an aqueous ammonia solution to perform salt exchange again, thereby obtaining an aqueous solution of ammonium styrenesulfonate. However, since toluidine, which is harmful and prone to coloration, is used, and further, the toluidine styrenesulfonate salt is solubilized in water by ammonium styrenesulfonate, contamination of ammonium styrenesulfonate with toluidine is unavoidable. Furthermore, as in Patent Document 7, when water is distilled off from an aqueous solution containing ammonium styrenesulfonate at a low concentration of about 10 wt%, to precipitate ammonium styrenesulfonate crystals, polymers are likely to be produced, and an appropriate polymerization inhibitor is not added, so there is a significant problem with the long-term storage stability required for industrialization.

[0007] Non-Patent Document 2 describes, for example, a method in which hydrogen chloride gas is blown into sodium styrenesulfonate dispersed in acetone to convert the sodium styrenesulfonate into acetone-soluble styrenesulfonic acid and acetone-insoluble sodium chloride, followed by filtering off the sodium chloride to recover an acetone solution of styrenesulfonic acid, which is then neutralized with ammonia to obtain ammonium styrenesulfonate. However, there are problems associated with the use of highly flammable organic solvents and toxic hydrogen chloride gas and ammonia gas, as well as the inevitable contamination of ammonium styrenesulfonate with ammonium chloride due to residual hydrogen chloride in the acetone solution of styrenesulfonic acid. Another important problem is the unavoidable contamination of polymers due to the high susceptibility of the reaction intermediate styrenesulfonic acid to spontaneous polymerization (also known as spontaneous polymerization or catalyst-free polymerization) (see, for example, Non-Patent Document 3).

[0008] Due to the above-mentioned background, ammonium styrenesulfonate has not yet been industrially developed, and there has been a strong demand for ammonium styrenesulfonate that has both storage stability and high purity suitable for the above-mentioned applications, as well as a simple and environmentally friendly method for producing the same.

[0009] Japanese Patent No. 3585588 Japanese Patent No. 3460246 Japanese Patent No. 5482194 Japanese Patent No. 6618355 Japanese Patent Application Laid-Open No. 2021-44537 International Publication No. 2020 / 184306 Japanese Patent Application Laid-Open No. 50-149642 Japanese Patent Application Laid-Open No. 51-26842

[0010] Jose M.Asua;European Polymer Journal, 2017, Vol. 93, pp. 480-494 Toyo Soda Research Report, Vol. 24, No. 1, 1980, pp. 3-11 JCSalamone; Polymer Letters Edition, Vol. 15, 1977, pp. 487-491

[0011] The present invention has been made in view of the above background and problems, and aims to provide an ammonium styrenesulfonate composition that combines long-term storage stability and high purity, and a simple and environmentally friendly method for producing the same that avoids the use of harmful and hazardous organic solvents and gases, for example.

[0012] As a result of extensive research, the present inventors have discovered that controlling the moisture, type and content of polymerization inhibitor, and specific metal content in ammonium styrenesulfonate compositions within specific ranges significantly improves the long-term storage stability that has been a problem in the past, and that reactive crystallization using an alkali metal styrenesulfonate salt, an inorganic ammonium salt, a specific polymerization inhibitor, and water as a solvent under specific conditions enables the production of a high-purity ammonium styrenesulfonate composition with excellent long-term storage stability without the use of harmful and hazardous organic solvents or gases, and without the need for strong acidic conditions that tend to produce polymers. The styrenesulfonate salts referred to below are usually para-isomers, but as is commonly known, also include positional isomers such as meta-isomers and ortho-isomers.

[0013] That is, the present invention relates to the following: [1] An ammonium styrenesulfonate composition having the following characteristics (1) to (6): (1) the ammonium styrenesulfonate content in the composition is 88.0% by weight or more, (2) the water content in the composition is 10.00% by weight or less, (3) the alkali metal content in the composition is 0.50% by weight or less, (4) the halogen content in the composition is 1.00% by weight or less, (5) the polymer content in the composition is 0.20% by weight or less, and (6) the polymerization inhibitor content in the composition is 2000 ppm or less [2] The ammonium styrenesulfonate composition according to item [1], having the following characteristics (1) to (6). (1) The ammonium styrenesulfonate content in the composition is 88.0% by weight or more; (2) The water content in the composition is 0.10% by weight to 10.00% by weight; (3) The alkali metal content in the composition is 0.50% by weight or less; (4) The halogen content in the composition is 1.00% by weight or less; (5) The polymer content in the composition is 0.20% by weight or less; and (6) The polymerization inhibitor content in the composition is 20 ppm to 2000 ppm. [3] The ammonium styrenesulfonate composition according to item [1], having the following characteristics (1) to (6):(1) the ammonium styrene sulfonate content in the composition is 94.00 wt% or more; (2) the water content in the composition is 0.10 wt% to 6.00 wt%; (3) the alkali metal content in the composition is 0.50 wt% or less; (4) the halogen content in the composition is 0.10 wt% or less; (5) the polymer content in the composition is 0.20 wt% or less; and (6) the polymerization inhibitor content in the composition is 20 ppm to 1000 ppm [4] The polymerization inhibitor is 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,5-dimethoxyphenol, 2,6-dimethoxyphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylcatechol, hydroquinone, methylhydroquinone, 2-methoxyhydroquinone, or tert-butylhydroquinone. , ammonium N-nitrosophenylhydroxylamine, 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, and salicylic acid hydrazide. [5] The ammonium styrenesulfonate composition according to any of items [1] to [3], wherein the polymerization inhibitor is at least one phenolic compound selected from the group consisting of 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,5-dimethoxyphenol, and 2,6-dimethoxyphenol. [6] The ammonium styrenesulfonate composition according to any one of items [1] to [3], wherein the charge amount per unit mass is 0.020 μC / g to 0.200 μC / g.[7] The ammonium styrenesulfonate composition according to any one of items [1] to [3], wherein the median diameter of the crystals in the composition is 30 μm to 700 μm. [8] The ammonium styrenesulfonate composition according to any one of items [1] to [3], wherein the median diameter of the ammonium styrenesulfonate crystals is 30 μm to 500 μm. [9] The ammonium styrenesulfonate composition according to any one of items [1] to [3], wherein the polymer content in the composition is 0.20 wt% or less when the composition is stored in a sealed state at 60°C for 60 days.

[10] The ammonium styrenesulfonate composition according to any one of items [1] to [3], having diffraction peaks at at least diffraction angles 2θ = 8.1 ± 0.2°, 15.2 ± 0.2°, 18.4 ± 0.2°, 20.6 ± 0.2°, 24.2 ± 0.2°, 32.5 ± 0.2°, and 43.0 ± 0.2° in a powder X-ray diffraction pattern measured by irradiation with copper Kα X-rays.

[11] The ammonium styrenesulfonate composition according to any one of items [1] to [3], having diffraction peaks at at least diffraction angles 2θ = 8.1 ± 0.2°, 15.2 ± 0.2°, 15.4 ± 0.2°, 18.4 ± 0.2°, 20.1 ± 0.2°, 20.6 ± 0.2°, 20.8 ± 0.2°, 24.2 ± 0.2°, 25.8 ± 0.2°, 27.5 ± 0.2°, 30.5 ± 0.2°, 32.5 ± 0.2°, 37.5 ± 0.2°, 43.0 ± 0.2°, and 49.6 ± 0.2° in a powder X-ray diffraction pattern measured by irradiation with copper Kα X-rays.

[12] A method for producing an ammonium styrenesulfonate composition, comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of 7 mol% or less of a polymerization inhibitor relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, followed by cooling to precipitate ammonium styrenesulfonate crystals, and filtering the crystals, wherein the ratio of ammonium cations charged to the alkali metal styrenesulfonate salt is 1.50 to 3.00 equivalents, the total solid content in the reaction system is 25.00 to 50.00% by weight, the temperature at which sodium or potassium styrenesulfonate is contacted with the inorganic ammonium salt is 30 to 80°C, and the temperature at which the precipitated crystals are filtered off is 5 to 30°C.

[13] The method for producing an ammonium styrenesulfonate composition according to any one of items [1] to [3],

[13] The method for producing an ammonium styrenesulfonate composition according to item

[12] , comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of 7 mol % or less of a polymerization inhibitor relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, then cooling to precipitate ammonium styrenesulfonate crystals, and filtering off the crystals, wherein the charging ratio of ammonium cations to alkali metal styrenesulfonate is 1.50 equivalents to 3.00 equivalents, the total solid content in the reaction system is 25.00 wt % to 45.00 wt %, the temperature at which sodium or potassium styrenesulfonate is brought into contact with the inorganic ammonium salt is 30°C to 80°C, and the temperature at which the crystals precipitated by cooling are filtered off is 5°C to 30°C.

[14] The method for producing an ammonium styrenesulfonate composition according to item

[12] , comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of 5 mol % or less of a polymerization inhibitor relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, then cooling to precipitate ammonium styrenesulfonate crystals, and filtering the crystals, wherein the charging ratio of ammonium cations to alkali metal styrenesulfonate is 2.00 equivalents to 2.50 equivalents, the total solid content in the reaction system is 35.00 wt % to 45.00 wt %, the temperature at which sodium or potassium styrenesulfonate is brought into contact with the inorganic ammonium salt is 40°C to 60°C, and the temperature at which the crystals precipitated by cooling are filtered is 5°C to 20°C.

[15] The method for producing an ammonium styrenesulfonate composition according to item

[12] , wherein the inorganic ammonium salt is at least one compound selected from the group consisting of ammonium chloride, ammonium sulfate, ammonium nitrate, and ammonium acetate.

[0014] The ammonium styrenesulfonate composition of the present invention can be produced without the use of hazardous and harmful raw materials or unstable intermediates, and by optimizing the composition, the purity loss and coloration during long-term storage, which have been obstacles to industrialization, are significantly reduced, making it extremely useful for the production of acrylic emulsions and the production of ammonium styrenesulfonate polymers for electronic materials.In addition, because the ammonium styrenesulfonate composition of the present invention is soluble in polar organic solvents, it is extremely useful for the production of electrolyte membranes and the modification of polymer substrates by graft polymerization.

[0015] Schematic diagram of wet crystals (composition) of AmSS. Proton nuclear magnetic resonance spectrum chart of the AmSS composition obtained in Example 1. The horizontal axis represents chemical shift (ppm), and the four decimal places at the bottom of the chart indicate the integral ratio of protons bonded to each carbon atom. Ha to He in the structural formula correspond to Ha to He near each peak, and the peak near 3 ppm corresponds to the methyl proton of dimethyl sulfone added as an internal standard. Optical microscope photograph of the AmSS composition obtained in Example 1 (100x magnification). The blue scale in the photograph represents 250 μm. Optical microscope photograph of the AmSS composition before drying obtained in Example 5 (100x magnification). The blue scale in the photograph represents 250 μm. Proton nuclear magnetic resonance spectrum chart of AmSS obtained in Comparative Example 11. The values ​​in the figure are the same as those in Figure 2. 7 is an optical microscope photograph (magnification: 200x) of AmSS obtained in Comparative Example 11. The scale indicated by the white line in the photograph represents 50 μm. This figure shows the powder X-ray diffraction pattern of the AmSS wet crystals obtained in Example 5. The vertical axis represents diffraction intensity (unit: counts), and the horizontal axis represents diffraction angle 2θ (unit: degrees). The numerical values ​​at the top of each peak in the figure indicate the detected angle of the peak top. This is an enlarged view of FIG. 7 (horizontal axis enlargement range: 10°≦2θ≦30°). The numerical values ​​in the figure are the same as those in FIG. 7. This figure shows the powder X-ray diffraction pattern of the AmSS dried crystals (wet crystals dried in a rotary evaporator) obtained in Example 5. The numerical values ​​in the figure are the same as those in FIG. 7. This is an enlarged view of FIG. 9 (horizontal axis enlargement range: 10°≦2θ≦30°). The numerical values ​​in the figure are the same as those in FIG. 7. This figure shows the powder X-ray diffraction pattern of NaSS, the raw material used in Example 5. The numerical values ​​in the figure are the same as those in FIG. 7. 11 (horizontal axis magnification range: 10°≦2θ≦30°). The values ​​in the figure are the same as those in FIG. 7. This is a diagram showing the powder X-ray diffraction pattern of dried AmSS crystals (wet crystals dried in a rotary evaporator) obtained in Example 6. The values ​​in the figure are the same as those in FIG. 7. This is an enlarged view of FIG. 13 (horizontal axis magnification range: 10°≦2θ≦30°). The values ​​in the figure are the same as those in FIG. 7.

[0016] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following embodiment. The present invention can be practiced by appropriately modifying it within the scope of its gist.

[0017] First, the characteristics of the ammonium styrene sulfonate (hereinafter abbreviated as AmSS) composition of the present invention will be described in detail.

[0018] Sodium styrenesulfonate (hereinafter referred to as NaSS), a raw material for the AmSS composition of the present invention, is a powdered vinyl monomer with extremely excellent storage stability, and when stored at room temperature, it does not show any decrease in purity or coloration due to spontaneous polymerization for at least 3 to 4 years after production. As shown in the flow chart below, NaSS is produced by reacting 4-(2-bromoethyl)benzenesulfonic acid with sodium hydroxide in water. However, the anhydrous salt (anhydrous crystals) has problems such as caking of the crystalline powder and a decrease in purity due to spontaneous polymerization within six months to a year at room temperature after production. It was subsequently discovered that by crystallizing the anhydrous salt of NaSS to form a hemihydrate (hemihydrate crystals), long-term storage stability can be dramatically improved (see, for example, JP-A-10-152465). Currently available NaSS is a hemihydrate with improved storage stability, and forms stable crystals from two molecules of NaSS and one molecule of water. However, in reality, in addition to the water of crystallization (theoretical value 4.4% by weight), it also contains adherent water (2% by weight to 3% by weight) derived from the slurry filtrate (mother liquor), so the total water content in the NaSS product is usually 6% by weight to 8% by weight. During the above reaction, sodium nitrite or the like is added as a polymerization inhibitor, and about 20 ppm to 100 ppm of nitrite remains in the NaSS product.

[0019]

[0020] On the other hand, because ammonia is weakly basic, AmSS cannot be produced directly from 4-(2-bromoethyl)benzenesulfonic acid and ammonia, and therefore, as mentioned above, attempts have been made to produce AmSS from commercially available NaSS. However, as mentioned above, there were significant issues with the production process, such as the use of dangerous and toxic raw materials, the need for unstable intermediates, the large number of steps, and the reaction at low substrate concentrations, which prevented industrialization.

[0021] Therefore, the present inventors investigated a simple and highly productive method for producing AmSS using only water as the reaction solvent. As a result, they surprisingly found that when commercially available lithium styrenesulfonate (hereinafter referred to as LiSS), inorganic ammonium salts, and small amounts of lithium nitrite or sodium nitrite are dissolved in water in a specific composition and then cooled, AmSS preferentially crystallizes to form a slurry. AmSS can be obtained very easily by filtering the slurry. Because the solubility of AmSS in water is only about half that of LiSS (see the Tosoh Finechem Corporation website (https: / / www.tosoh-finechem.co.jp)), AmSS preferentially crystallizes, leaving highly soluble unreacted LiSS and other inorganic salts in the mother liquor. However, the storage stability of this AmSS is poor, and even when stored at a low temperature, it suffers from issues of purity loss and coloration due to spontaneous polymerization within 1 to 2 months after preparation. The reason for this is suggested to be that nitrite, which acts as a stabilizer for NaSS and LiSS, may not act on AmSS.

[0022] Therefore, the present inventors have conducted a detailed investigation into the factors that affect the storage stability of the AmSS. As a result, they have found that the following components (1) to (3) and their amounts are important, and that by controlling these components within specific ranges, it is possible to significantly suppress the decrease in purity and coloration due to polymerization during long-term storage. (1) The content of water in the AmSS composition, (2) The type and content of polymerization inhibitor in the AmSS composition, and (3) The type and content of residual metals in the AmSS composition.

[0023] The characteristics of the AmSS composition of the present invention are described in more detail below. Specifically, (1) the water content in the AmSS composition is 10.00 wt% or less, with a lower content being preferable in terms of storage stability and fluidity, more preferably 6.00 wt% or less, and particularly preferably 5.00 wt% or less. On the other hand, the lower the water content, the more easily the composition becomes charged, increasing the risk of scattering or dust explosion during handling. Furthermore, a long drying process is required to minimize the moisture content. Therefore, in practice, the water content in the composition is 0.10 wt% or more. (2) The content of the polymerization inhibitor contained in the AmSS composition depends on the type of polymerization inhibitor, but is usually 20 ppm or more, more preferably 100 ppm or more. If the polymerization inhibitor content is less than 20 ppm, sufficient stability may not be achieved. Conversely, if the amount is too high, it can adversely affect the polymerization rate, degree of polymerization, and hue of the AmSS composition when it is used, so the content is 2000 ppm or less, more preferably 1000 ppm or less, and even more preferably 500 ppm or less. (3) The coloration mechanism of the AmSS composition is not entirely clear, but it is presumed to involve interactions between alkali metals such as lithium metal, nitrous acid, and phenolic polymerization inhibitors. The lower the lithium and nitrous acid content, the better, with lithium preferably being 20 ppm or less, usually 1 ppm or less, and nitrous acid preferably being 20 ppm or less. The nitrous acid content referred to here is basically derived from sodium nitrite and lithium nitrite contained in the raw materials NaSS and LiSS, and is the nitrite anion, which can be quantified by ion chromatography or the like. In the present invention, the purity of the AmSS composition is preferably 88.00% by weight or more, more preferably 94.00% by weight or more, and particularly preferably 95.00% by weight or more. However, since water is the main impurity, the purity can be improved by forcibly drying the AmSS composition or washing it with a water-soluble organic solvent such as alcohol or acetone to reduce the water content.

[0024] The polymerization inhibitor is not particularly limited as long as it is soluble in water or the reaction solution and inhibits the spontaneous polymerization of AmSS. Examples of the polymerization inhibitor include phenolic polymerization inhibitors such as 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,6-dimethoxyphenol, 2,5-dimethoxyphenol, 4-isopropoxyphenol, 1,4-dihydroxy-2-methoxybenzene, hydroquinone, methylhydroquinone, 2-methoxyhydroquinone, and 2,4-dinitrophenol; semi-hindered phenolic polymerization inhibitors such as 4-tert-butylcatechol, butylhydroxyanisole, and tert-butylhydroquinone; and 2,6-di-tert-butyl catechol. hindered phenol-based polymerization inhibitors such as 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,5-di-tert-butylhydroquinone; stable nitroxyl radical-based polymerization inhibitors such as 4-hydroxy-2,2,6,6-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; and polymerization inhibitors such as ammonium N-nitroso-N-phenylhydroxyamine, L-ascorbic acid, erythorbic acid, catechin, tocopherol, and urea.Among these, from the viewpoints of compatibility with AmSS, solubility during reaction, and discoloration resistance, the same aromatic phenols as AmSS, such as 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,5-dimethoxyphenol, and 2,6-dimethoxyphenol, as well as 4-hydroxy-2,2,6,6-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, which have high polymerization inhibitory properties, are more preferred. Nitrite-based polymerization inhibitors, such as sodium nitrite and lithium nitrite, which are used in the production of NaSS and LiSS, can adversely affect the discoloration resistance of AmSS, so they are preferably avoided.

[0025] Furthermore, the AmSS composition of the present invention has a charge density per unit mass of 0.200 μC / g or less. As the charge density per unit mass increases beyond 0.200 μC / g, the AmSS composition becomes more easily charged, increasing the tendency for scattering and dust explosion during handling. While ensuring storage stability is the most important factor, controlling the moisture content of the AmSS composition within the above-mentioned range makes it possible to achieve both low charge density and high storage stability.

[0026] Furthermore, although this does not directly affect the spontaneous polymerization or colorability of AmSS, the median diameter of AmSS crystals in the AmSS composition is preferably 30 μm to 700 μm from the viewpoint of ensuring moisture absorption resistance, high fluidity, low dust generation, and dust explosion resistance. As described below, larger and thicker AmSS crystals are preferable because they provide better drainage and improve the purity of AmSS. However, excessively large crystal sizes can actually decrease drainage, so a median diameter of 500 μm or less is more preferable. On the other hand, if the median diameter is less than 30 μm, drainage is significantly reduced. Furthermore, even if the crystal size of AmSS after filtration or drying is large, when the crystals or crystal aggregates are stirred or disintegrated using a crusher or the like, they will be broken down and reduced in size. However, from the viewpoint of suppressing moisture absorption, dust generation, and dust explosion resistance, it is preferable to maintain a median diameter of 30 μm or greater.

[0027] When the AmSS composition of the present invention is stored in a sealed state at 60°C for at least 60 days, the polymer content in the composition is 0.20% by weight or less, and the storage stability is extremely excellent due to moisture control and the presence of an appropriate polymerization inhibitor. Furthermore, if the AmSS composition becomes discolored due to oxidation of AmSS or the polymerization inhibitor, this is not preferable for applications where color is important, such as paints and adhesives. For example, the AmSS composition of the present invention stored in a sealed state at 60°C for 60 days preferably has an APHA value of 100 or less when made into a 10% by weight aqueous solution. The water content in the AmSS composition is １ The quantity can be determined by H-NMR, Karl Fischer moisture meter, dry weight method using a thermostatic dryer, infrared moisture meter, etc. Among these, the infrared moisture meter is the simplest and has good reproducibility.

[0028] The content of ammonium styrenesulfonate in the AmSS composition, i.e., purity, can be determined by quantification of active vinyl groups by oxidation-reduction titration (see, for example, JP 2014-80505 A, paragraph 0055), proton nuclear magnetic resonance spectroscopy ( １ The amount can be determined by 1 H-NMR, high performance liquid chromatography (HPLC), or the like. １When quantifying by H-NMR, for example, the AmSS composition and a compound such as dimethyl sulfone as an internal standard are precisely weighed and dissolved in a deuterated solvent such as deuterated dimethyl sulfoxide. １ H-NMR is measured. The amount of ammonium styrene sulfonate in the AmSS composition can be quantified from the ratio of the integral value of the methyl protons of dimethyl sulfone to the integral value of the protons derived from the styrene sulfonic acid skeleton, for example, the protons of the vinyl group. However, since neither of the above methods can distinguish between alkali metal styrene sulfonates and ammonium styrene sulfonates, it is necessary to use elemental analysis or １ It is necessary to confirm the molar ratio of ammonium cations to styrenesulfonic acid units and the metal content by H-NMR.

[0029] In the present invention, the crystal shape of the obtained AmSS composition is usually approximately circular or square plate-like, and its shape and size can be measured using an optical microscope or electron microscope. However, in the present invention, the median diameter, which can be easily and reproducibly measured using a laser diffraction / scattering particle size distribution analyzer, is used. A laser diffraction / scattering particle size distribution analyzer calculates particle size by regarding the sample as spherical particles. The median diameter is the diameter at which the larger and smaller particles are equal when the sample is divided into two at a certain particle diameter. In addition, the content of the polymerization inhibitor in the AmSS composition can be quantified using gas chromatography (GC), high-performance liquid chromatography (HPLC), ion chromatography (IC), or the like, depending on the type of polymerization inhibitor.

[0030] The alkali metals and halogens that may be contained in the AmSS composition of the present invention are impurities derived from the raw materials. Considering use in aqueous coatings, the lower the amount, the better. Typically, the alkali metal content in the composition is preferably 0.50 wt% or less, and the halogen content is preferably 1.00 wt% or less. Considering use in electronic materials, the alkali metal content in the composition is more preferably 0.50 wt% or less, and the halogen content is more preferably 0.10 wt% or less. Furthermore, when dissolving the AmSS composition in a polar organic solvent to produce a polymer, the higher the alkali metal content, such as sodium, the more likely the polymer is to precipitate during polymerization, so the lower the content is, the better. These metal contents can be quantified using inductively coupled plasma spectroscopy (ICP-AES) or other methods. Impurities such as halogens can be quantified using ion chromatography (IC) or the Volhard method.

[0031] The polymers that may be contained in the AmSS composition of the present invention are impurities derived from raw materials or generated during production or storage. When AmSS is used to produce an acrylic emulsion, the higher the polymer content in the AmSS composition, the lower the colloidal stability and physical properties of the emulsion coating film, so the lower the polymer content is, preferably 0.20 wt% or less, and more preferably 0.10 wt% or less. Furthermore, when solid compounds such as AmSS are actually used on an industrial scale, AmSS is often dissolved in water or an organic solvent and filtered. However, the presence of polymer content dramatically deteriorates filterability, so it is preferable to keep the polymer content as low as possible. In particular, when AmSS is dissolved in an organic solvent and filtered, not only polymer content but also inorganic impurities such as sodium and inorganic ammonium salts deteriorate filterability, so it is preferable to keep the polymer content as low as possible. The amount of charge per unit mass of the AmSS composition can be measured using a small air transport type charge evaluation device (Suzuki Teruo; Journal of the Electrostatic Society of Japan, Vol. 25, vol. 1, pp. 37-44, 2001), an electrolytic flying type charge measurement device (DIT Corporation), an E-SPART analyzer (Tsuji Keishi; Pulverization, No. 5, pp. 84-88, 2014), or the like.

[0032] The method for producing the AmSS composition of the present invention is described below. As described above, the inventors have succeeded in finding a composition that maintains long-term storage stability without impairing the polymerizability of the AmSS composition when it is used. They then conducted extensive research into a simple method for producing the AmSS composition. The targeted process can be simply represented by the following flow chart. The process is based on the cation exchange reaction between an alkali metal styrene sulfonate and an inorganic ammonium salt, just like the conventional method.

[0033]

[0034] As mentioned above, AmSS can be easily obtained by the cation exchange reaction of LiSS with an inorganic ammonium salt. However, because the solubility of LiSS in water is about twice as high as that of AmSS, AmSS crystallizes preferentially. In contrast, the production method of the present invention uses NaSS or potassium styrene sulfonate (hereinafter referred to as KSS), which have lower solubility in water than AmSS. It is generally difficult to imagine that high-purity AmSS can be obtained under such conditions. However, as a result of our investigations, we surprisingly found that AmSS crystallizes preferentially under high substrate concentration conditions. In other words, we found that AmSS crystallization can be obtained simply by filtering the aqueous slurry shown in the above flow chart.

[0035] Since AmSS is a strong electrolyte-type hydrophilic compound, adhesion of the mother liquor (filtrate) is unavoidable, resulting in the formation of wet crystals (compositions) as shown in the schematic diagram in Figure 1. The amount of impurities in the AmSS composition is determined by the amount of adhesion of the mother liquor, which contains a high concentration of inorganic salts. While it would be ideal to grow AmSS crystals in a reaction system with low adhesion of the mother liquor, i.e., with excellent drainage properties, it has been found that a relatively high total substrate concentration is required to obtain high-quality AmSS crystals. In other words, since a high substrate concentration is synonymous with a high salt concentration in the mother liquor, improving drainage properties does not reduce the impurity concentration in the AmSS composition. The inventors have discovered sophisticated manufacturing conditions that can achieve both storage stability and high purity of AmSS.

[0036] The reason why AmSS crystallizes preferentially under the production conditions of the present invention is not entirely clear, but is presumed to be the following. First, water with a high dielectric constant is used as the reaction solvent instead of an organic solvent, and 1.50 equivalents or more of ammonium cations are added to NaSS (sodium styrenesulfonate) or KSS (potassium styrenesulfonate). Since the degree of ionic dissociation of both is high, these conditions can be said to be favorable for at least the cation exchange reaction to proceed. Second, the difference in cation size is considered to be a factor. That is, the size of lithium cations is generally smaller than that of sodium cations, which in turn are smaller than that of ammonium cations. However, it is known that the smaller the cation size, the more easily it is hydrated. For example, when LiSS, NaSS, and AmSS are actually crystallized from aqueous solutions, LiSS tends to form extremely fine needle-like crystals, resulting in poor drainage and an adhering water content well exceeding 20% ​​by weight. On the other hand, NaSS forms large circular plate crystals, while AmSS tends to form large rectangular plate crystals, so its drainage is better than that of LiSS. The amount of adhering water is at least less than 20% by weight, and depending on the crystallization conditions, it can be as low as a few weight percent. It has been found that AmSS in particular tends to form large, thick crystals. These facts are thought to be related to the reason why a high-purity AmSS composition can be obtained under the conditions of the present invention.

[0037] The production method is described in more detail below. First, a reactor is charged with water, an alkali metal styrene sulfonate salt, an inorganic ammonium salt, and a polymerization inhibitor in a specific composition, and the raw materials are dissolved or partially dissolved while stirring at a specific temperature for a specific time. Subsequently, AmSS crystals are precipitated and grown while cooling to a predetermined temperature at a specific rate. The precipitated AmSS crystals are then filtered off to obtain the AmSS composition of the present invention. The alkali metal styrene sulfonate salt used can be a sodium salt or a potassium salt. While alkaline earth metal styrene sulfonates such as calcium styrene sulfonate can also be used, the mass-produced sodium salt is more preferred. Examples of inorganic ammonium salts include ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium acetate. However, considering cost and other economical considerations, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate are more preferred. Furthermore, considering the solubility of the alkali metal salts by-produced by cation exchange, ammonium chloride, ammonium sulfate, and ammonium nitrate are more preferred. Furthermore, when taking into consideration residual halogens, ammonium sulfate and ammonium nitrate are more preferable. However, even if AmSS is produced using ammonium chloride, a high-purity AmSS composition with few impurities such as halogens can be produced by purifying it using the method described below. The polymerization inhibitor is as described above.

[0038] First, the charge composition for the reaction will be explained. The charge ratio of ammonium cation to alkali metal styrene sulfonate is preferably 1.50 to 3.00 equivalents. If the equivalent ratio is less than 1.50 equivalents, the cation exchange rate is low and the salt concentration in the system is reduced, making it difficult to produce high-quality AmSS crystals with good drainage properties. On the other hand, if the equivalent ratio exceeds 3.00 equivalents, no improvement in drainage properties is observed, and instead the inorganic salt concentration in the adhering mother liquor increases, which may result in a decrease in the purity of the AmSS composition. From the viewpoint of the balance between the inorganic salt concentration in the mother liquor and drainage properties, a ratio of 2.00 to 2.50 equivalents is more preferable.

[0039] The total solids content in the reaction system is preferably 25.00 wt% to 50.00 wt%. A total solids content of less than 25.00 wt% not only reduces the yield but also reduces drainage, while a total solids content of more than 50.00 wt% increases the inorganic salt concentration in the mother liquor, potentially reducing the purity of the AmSS composition. From the viewpoint of the balance between the inorganic salt concentration in the mother liquor and drainage, a total solids content of 25.00 wt% to 45.00 wt%, 30.00 wt% to 45.00 wt%, and more preferably 35.00 wt% to 45.00 wt% is preferred. Here, the total solids content refers to the sum of raw materials present in the reaction system that are solid at room temperature, impurities contained in the raw materials that are solid at room temperature, and by-products that are solid at room temperature.

[0040] The reaction temperature is preferably 30°C to 80°C. In the above-mentioned charged composition, if the reaction temperature is less than 30°C, the cation exchange rate may be insufficient, whereas if it exceeds 80°C, the cation exchange rate improves but polymers may be more likely to be produced; therefore, 30°C to 60°C is more preferable, and 40°C to 60°C is even more preferable. The reaction time is 10 minutes to 20 hours and can be adjusted depending on the substrate concentration and reaction temperature; however, in order to prevent spontaneous polymerization during the reaction, 30 minutes to 20 hours, more preferably 10 minutes to 10 hours, and particularly preferably 30 minutes to 10 hours, is preferable.

[0041] The cooling and filtration temperature is 5°C to 30°C, and after reaching the predetermined cooling temperature, the mixture is further aged for 0.5 to 5 hours. A cooling temperature lower than 5°C may increase impurities such as inorganic salts and moisture in the AmSS composition, while a temperature higher than 30°C may significantly reduce the yield. Therefore, a cooling temperature of 5°C to 25°C is more preferable, with a cooling rate of 5°C to 20°C being even more preferable. The cooling rate can be adjusted depending on the heating temperature and total solids content, but a cooling rate of 3°C to 40°C per hour is preferred. If the cooling rate is too fast, the crystal size may become smaller and drainage may decrease. As a result, the moisture and inorganic salts in the AmSS composition may increase. On the other hand, if the cooling rate is extremely slow, the crystals may collapse and drainage may decrease, so a cooling rate of 5°C to 30°C per hour is more preferable.

[0042] To increase the crystal size of AmSS and improve drainage, so-called temperature swing crystallization is more preferred, in which the mixture is cooled to a predetermined temperature to precipitate crystals, then reheated to a temperature at which all the crystals do not dissolve, and cooled again. Furthermore, when charging each raw material into a reactor, it may be charged as a powder, or it may be charged as a saturated aqueous solution of each raw material. The charging method may be either batch or sequential charging. Dropping an aqueous solution or saturated aqueous solution of an inorganic ammonium salt into an aqueous solution or slurry of an alkali metal styrenesulfonate reduces the inclusion of the inorganic salt into the precipitated AmSS crystals, thereby producing a higher quality AmSS composition. Furthermore, adding a powder or slurry of an alkali metal styrenesulfonate salt to an aqueous solution of an inorganic ammonium salt may be used, but this is disadvantageous in terms of powder scattering and the sedimentation of the slurry. The reaction system may be in an inert atmosphere or an air atmosphere, but an air atmosphere is preferred from the viewpoint of suppressing spontaneous polymerization during the reaction.

[0043] In addition, in order to increase the crystal size of AmSS and improve drainage, AmSS can be added as seed crystals from the start of the reaction to the cooling period. The amount of seed crystals added is preferably 1.0 mol % to 20.0 mol % based on the styrene sulfonic acid units in the system, and more preferably 1.0 mol % to 10.0 mol % in consideration of productivity and thermal history.

[0044] The molar ratio of ammonium cations to alkali metal styrenesulfonate specified in the production method of the present invention varies depending on the addition of AmSS seed crystals. However, the ammonium cations referred to here are limited to those derived from the inorganic ammonium salts charged as raw materials, and do not include ammonium cations derived from the seed crystals.

[0045] To increase the yield of AmSS, a water-soluble organic solvent, which is a poor solvent, may be added to the reaction system. Examples of such a poor solvent include alcohols such as methanol, ethanol, and 2-propanol, ketones such as acetone, nitriles such as acetonitrile, and ethers such as tetrahydrofuran. However, from the viewpoints of increasing inorganic impurities in the AmSS composition, environmental load, and explosion prevention, the use of water alone as a solvent is preferred for industrial procedures.

[0046] The slurry can be filtered using methods such as centrifugal filtration, pressure filtration, vacuum filtration, and filter press, but centrifugal filtration is more preferred because it has a high processing capacity and can be completed in a relatively short time. Furthermore, impurities can be further reduced by recrystallizing the obtained AmSS composition using water or a mixed solvent of water and the above-mentioned water-soluble organic solvent. From the perspective of productivity, the total solids content in the system is preferably 50.00 wt% to 60.00 wt%, the heating temperature is preferably 40°C to 60°C, and the cooling and filtration temperatures are preferably 10°C to 25°C. When recrystallizing and purifying, it is preferable to add 7 mol% or less of the above-mentioned polymerization inhibitor to AmSS.

[0047] In addition, the lower the moisture content of the AmSS composition, the better its storage stability. Therefore, the water content of the AmSS composition can be reduced by washing the AmSS composition with the above-mentioned water-soluble organic solvent. The AmSS composition may also be dried using a tray vacuum dryer, a conical agitator dryer (Nauta mixer), a vacuum rotary dryer (conical dryer), a rotary kiln dryer, a spray dryer, a pleated dryer, a double-cylinder drying filter, a vacuum vibration dryer, or the like. However, depending on the drying conditions, such as the heating temperature, ammonia may volatilize, reducing the degree of ammonia neutralization of styrene sulfonic acid, which may actually reduce the storage stability of the AmSS composition. Therefore, it is recommended to maintain the degree of ammonia neutralization at 100% as much as possible.

[0048] As a result of detailed investigations, the inventors have found that, as mentioned above, commercially available NaSS is stabilized by hemihydrate crystals, whereas the AmSS composition of the present invention is stabilized by anhydrous salt crystals. Specifically, the water content of commercially available NaSS consists of crystal water and attached water, and removing these requires a relatively high temperature or vacuum. However, since the water content of the AmSS composition is attached water, it can be removed at a lower temperature or vacuum. For example, drying can be performed using dry air at room temperature or an inert gas stream. The drying temperature is preferably 20°C to 70°C, and more preferably 20°C to 40°C, taking into account the volatilization of the polymerization inhibitor and the polymerization of AmSS.

[0049] The AmSS composition of the present invention is soluble in water and can therefore be used to produce aqueous polymer emulsions, hollow polymer particles, aqueous solutions of ammonium polystyrene sulfonate, and the like. In addition, it is soluble in polar organic solvents and is therefore extremely useful for producing polymer electrolyte membranes (e.g., U.S. Pat. No. 6,221,248) and for surface modification of organic materials using graft polymerization (e.g., Kyoichi Saito, Polymer Adsorbent Revolution by Graft Polymerization, pp. 8-10, Maruzen Publishing, published in 2014; NHV Corporation website: https: / / www.nhv.jp / blog / post723 / ).

[0050] Powder X-ray diffraction (PXRD) patterns can be measured by standard protocols. As described above, the AmSS composition of the present invention is presumed to be stabilized by anhydrous salt crystals, and the PXRD patterns are presumed to result from this. The AmSS composition of the present invention has diffraction peaks at least at diffraction angles 2θ of 8.1±0.2°, 15.2±0.2°, 15.4±0.2°, 18.4±0.2°, 20.1±0.2°, 20.6±0.2°, 20.8±0.2°, 24.2±0.2°, 25.8±0.2°, 27.5±0.2°, 30.5±0.2°, 32.5±0.2°, 37.5±0.2°, 43.0±0.2°, and 49.6±0.2°, and particularly has strong diffraction peaks at diffraction angles 2θ of 8.1±0.2°, 15.2±0.2°, 18.4±0.2°, 20.6±0.2°, 24.2±0.2°, 32.5±0.2°, and 43.0±0.2°. This PXRD pattern is clearly different from that of sodium styrenesulfonate stabilized by hemihydrate crystals. The typical error in peak position is ±0.2°, and this slight error can arise from sample preparation, the measuring instrument, handling by the measurer, etc. Regarding the diffraction peak value, for example, "8.2±0.2°" means that the diffraction peak is somewhere in the range of 8.0° to 8.4° (i.e., 8.0°≦2θ≦8.4°).

[0051] 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.

[0052] <Chemicals used> Sodium styrenesulfonate (NaSS): manufactured by Tosoh Finechem Corporation, purity 88.2%, sodium bromide 2.2% by weight, sodium hydroxide 0.40% by weight, sodium sulfate 0.50% by weight, water 7.2% by weight, polymer content 0.01% by weight, nitrite content 70 ppm Lithium styrenesulfonate (LiSS): manufactured by Tosoh Finechem Corporation, purity 85.3% by weight, lithium bromide 2.5% by weight, lithium hydroxide 0.45% by weight, lithium sulfate 0.50% by weight, water 7.1% by weight, polymer content 0.04% by weight, nitrite content 60 ppm Ammonium chloride: manufactured by Fujifilm Wako Pure Chemical Corporation, special grade reagent Ammonium sulfate: manufactured by Fujifilm Wako Pure Chemical Corporation, special grade reagent Ammonium nitrate: manufactured by Fujifilm Wako Pure Chemical Corporation, special grade reagent Diammonium hydrogen phosphate: manufactured by Fujifilm Wako Pure Chemical Corporation, special grade reagent 4-Methoxyphenol: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent. 2-Methoxyphenol: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent. 4-Ethoxyphenol: Tokyo Chemical Industry Co., Ltd., purity >98%. 2,6-Dimethoxyphenol: Tokyo Chemical Industry Co., Ltd., purity >98%. Methylhydroquinone: Tokyo Chemical Industry Co., Ltd., purity >98%. 4-t-Butylcatechol: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent. 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl: Tokyo Chemical Industry Co., Ltd., purity >98%. Lithium nitrite: Honjo Chemical Co., Ltd., 40% by weight aqueous solution. Phenolic antioxidant emulsion (Antage 3LX): Kawaguchi Chemical Industry Co., Ltd. 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (V-50): Fujifilm Wako Pure Chemical Industries, Ltd., first grade reagent. Dimethyl sulfone: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent N-methylpyrrolidone: Fujifilm Wako Pure Chemical Industries, Ltd., special grade reagent

[0053] <Quantitative Determination of Moisture Content of AmSS> Measurement was carried out using an infrared moisture meter under the following conditions: Apparatus: FD-720 manufactured by Kett Electric Laboratory Co., Ltd. Conditions: Approximately 5 g of sample was taken and heated at 120°C for 20 minutes.

[0054] <Analysis of AmSS Purity by Redox Titration> The active double bonds were quantified by the following redox titration method to determine the AmSS purity (i.e., including the para isomer as well as the ortho and meta isomers). (1) Instruments and Equipment 1) Weighing bottle: diameter 50 mm, depth 70 mm 2) 500 ml and 1000 ml measuring flasks 3) 500 ml Erlenmeyer flask with ground stopper 4) Electronic analytical balance (2) Reagents 1) Bromine solution: potassium bromide (KBr) 22.00 g, potassium bromate (KBrO ３ ) 3.00 g was dissolved in pure water to make a total of 1000 ml. 2) Sulfuric acid aqueous solution (concentrated sulfuric acid / pure water volume ratio = 1 / 1) 3) Potassium iodide aqueous solution (200 g / L) 4) 0.1 mol / L sodium thiosulfate aqueous solution 5) Starch aqueous solution: 6.00 g of starch was dissolved in pure water to make a total of 1000 ml. (3) Procedure 1) Weigh 20 g of sample into a weighing bottle to the nearest 0.1 mg. 2) Rinse and transfer to a 500 ml measuring flask with pure water to make the volume approximately 400 ml. 3) Add a magnetic rotor and stir to dissolve the sample. 4) Remove the rotor, align the gauge with pure water, shake, and use the test solution. 5) Add 25 ml of bromine solution to a 500 ml Erlenmeyer flask with a stopper and place 200 ml of pure water in it. 6) After adding 5 ml of the test solution, add 10 ml of sulfuric acid aqueous solution, seal, and let stand for 20 minutes. 7) Quickly add 10 ml of potassium iodide aqueous solution and leave for 10 minutes. 8) Titrate with sodium thiosulfate aqueous solution. After the yellow color of the solution fades, add 1 ml of starch solution as an indicator and titrate until the blue color of the resulting iodine starch disappears. 9) Separately, as a blank test, add 200 ml of pure water to a stoppered Erlenmeyer flask, add 25 ml of bromine solution, quickly add 10 ml of potassium iodide aqueous solution and 10 ml of sulfuric acid aqueous solution, and repeat operation 8). (4) Calculation Calculate the AmSS content using the following formula: A = 100 x [0.01006 x (a - b) x f] / (S x 5 / 500) A: AmSS content (%) a: Sodium thiosulfate aqueous solution required for the blank test (ml) b: Sodium thiosulfate aqueous solution required for the main test (ml) f: Titer of sodium thiosulfate aqueous solution S: Sample size (g)

[0055] <Elemental analysis of AmSS> Carbon, hydrogen, and nitrogen contents were quantified using an elemental analyzer. Apparatus: PerkinElmer 2400 II

[0056] <Quantitative Determination of Sulfur Content of AmSS> The combustion gas of the AmSS composition was burned by an oxygen flask combustion method, and the resulting hydrogen peroxide absorbing solution was absorbed. The sulfate ion concentration in the absorbed solution was then quantified by ion chromatography (see the next section for measurement conditions) and converted to sulfur content.

[0057] <Quantification of bromine, chlorine, sulfate, nitrate, and nitrite anions in AmSS> Quantification was performed using ion chromatography under the following conditions. Apparatus: Tosoh Corporation, IC-2010 Column: TSKgel® guard column Super IC-AHS (4.6 mm I.D. × 1 cm) + TSKgel® Super IC-Anion HS (4.6 mm I.D. × 10 cm) Column temperature: 40°C, injection volume: 30 μl, flow rate: 1.5 ml / min Eluent: Carbonate buffer solution (7.5 mM NaHCO3 + 0.8 mM Na2CO3) Sample solution preparation: The AmSS composition was dissolved in ultrapure water and diluted 10-fold, and the solution was passed through a pretreatment cartridge (TOYOPAK® ODSM) to prepare a measurement sample. Calibration curve: Absolute calibration curve method using a standard solution

[0058] <Proton nuclear magnetic resonance ( １ Analysis of AmSS by H-NMR> The AmSS content, water content, and the molar ratio of ammonium cation to styrene sulfonic acid units were analyzed under the following conditions. (1) Sample preparation The sample was dissolved in approximately 0.7 mL of dimethyl sulfoxide-d6 (99.5 wt%) containing approximately 0.05 wt% tetramethylsilane as an internal standard to prepare a sample for measurement. (2) Measuring equipment and conditions Model = Bruker AV-400M Number of accumulations = 16 Nuclide = 1H (3) Ammonium cation (NH ４ Calculation of the molar ratio of NH ) / styrene sulfonic acid unit (SS) was carried out using the following formula: ４ / SS = [n / (nH)] / [s / (sH)] s: integral value of the peak derived from the vinyl group of SS (peak position: δ 5.30 ppm, d) n: integral value of the peak derived from NH4 (peak position: δ 7.22 ppm, s, however, depending on the water content, it may split into three) sH: number of hydrogen atoms in the s peak (= 1) nH: number of hydrogen atoms in the n peak (= 4) Note that the peak positions are when dimethyl sulfoxide-d6 is used as the heavy solvent, and the chemical shift may fluctuate slightly depending on the amount of impurities. (4) Water (H ２ Calculation of the molar ratio of H to styrene sulfonic acid units (SS) was carried out using the following formula: ２ O / SS = [m / (mH)] / [s / (sH)] s: integral value of the peak derived from the vinyl group of SS (peak position: δ 5.30 ppm, d) m: integral value of the peak derived from HO (peak position: δ 3.40 ppm, s) sH: number of hydrogen atoms in the s peak (= 1) mH: number of hydrogen atoms in the m peak (= 2) Note that, since dimethyl sulfoxide-d6 may contain water, the water content in dimethyl sulfoxide-d6 was quantified in advance and the integral value was corrected. (5) Calculation of AmSS content The AmSS content in the AmSS composition was calculated using the following formula. AmSS content (wt%) = (B / Mb) x (a / aH) / (b / bH) x Ma / S x 100 a: Integrated value of the peak derived from the vinyl group of AmSS (peak position: δ 5.30 ppm, d) b: Integrated value of the peak derived from the internal standard substance dimethyl sulfone (peak position: δ 3.00 ppm, s) aH: Number of hydrogen atoms in the peak of a (= 1) bH: Number of hydrogen atoms in the peak of b (= 6) Ma: Molecular weight of AmSS Mb: Molecular weight of the internal standard substance B: Amount of internal standard collected (g) S: Amount of sample collected (g)

[0059] <Analysis of Alkali Metal Content in AmSS> The sodium and lithium contents were quantified using a frequency inductively coupled plasma atomic emission spectrometer OPTIMA 8300 (manufactured by PerkinElmer) (hereinafter abbreviated as ICP-AES). The target sample was wet decomposed with sulfuric acid and nitric acid, and the decomposed sample was heated to dryness. Nitric acid was added to the dried sample and dissolved by heating. After the predetermined volume was measured, 1 ppm of scandium was added as an internal standard and quantified.

[0060] Analysis of AmSS polymer content and polymerization inhibitor: Analysis was performed using gel permeation chromatography (GPC) under the following conditions: Apparatus: HLC-8320 manufactured by Tosoh Corporation; Column: TSKgel® guard column AW-H / TSKgel® AW-6000 / TSKgel® AW-3000 / TSKgel® AW-2500; Eluent: 0.05 M aqueous sodium sulfate / acetonitrile = 65 / 35 (volume ratio) solution; Sample: A 1 wt% solution (as is) of AmSS composition was prepared using the above eluent; Flow rate, injection volume, and column temperature: 0.6 ml / min, injection volume: 10 μl, column temperature: 40°C; Detector: UV detector (wavelength 230 nm); Calibration curve: Standard solutions of different concentrations of polystyrene sodium sulfonate were prepared using polystyrene sodium sulfonate (3K manufactured by Sowa Scientific Co., Ltd.) and the above eluent, and a calibration curve was created. All absorption peaks with elution times less than 13.00 minutes were considered to be polymer components. A calibration curve was also prepared for the polymerization inhibitor in the same manner.

[0061] <Measurement of polymerization conversion rate and molecular weight during AmSS polymerization> Measurement was performed by GPC under the same conditions as above (except that the sample concentration was 0.1 wt%). The molecular weight was calculated automatically using the internal software after creating a calibration curve from the peak top molecular weight and elution time of standard polystyrene sodium sulfonate (manufactured by Sowa Scientific Co., Ltd., 3K, 15K, 41K, 300K, 1000K, 2350K, 5000K). The polymerization conversion rate was calculated from the peak area (a) of the monomer and the peak area (b) of the polymer using the following formula: Conversion rate (area%) = 100 x [1 - {a / (a + b)}]

[0062] <Confirmation of long-term storage stability of AmSS> AmSS was sealed in a glass sample bottle and aged for a predetermined time in an oven at 60°C. The sample was then returned to room temperature and the APHA value and polymer content were measured. The APHA value was measured under the same conditions as below, and the polymer content was measured by the same GPC as above (sample concentration: 1 wt%).

[0063] <Analysis of the hue of AmSS> APHA value: A color difference meter (ZE-6000, manufactured by Nippon Denshoku Industries Co., Ltd.) was turned on and allowed to stabilize for 30 minutes. The measurement method was set to transmitted light, and the light source / viewpoint settings were set to C / 2. Water was placed in a square cell (cell length 36 mm) and standard calibration was performed. An aqueous solution of AmSS adjusted to 10 wt % (as-is standard) was then transferred and set in the square cell, and the APHA value was measured.

[0064] <Measurement of AmSS Median Diameter> Measurement was performed using a Microtrac particle size analyzer (MT-3300EXII, manufactured by Nikkiso Co., Ltd.) under the following conditions. Approximately 0.5 g of the AmSS composition was added to 200 ml of hexane to prepare a sample solution. The sample solution was irradiated with a laser beam, and the diffraction (scattering) was measured to determine the particle size. When preparing the sample solution, no ultrasonic or other treatment was performed, and measurements were performed under the following set conditions: particle transmittance = transparent, particle shape = aspherical, particle refractive index = 1.81, and solvent refractive index = 1.38. Furthermore, since dispersibility in hexane decreases when the water content of the AmSS composition exceeds 10 wt%, the AmSS composition was previously dried using a rotary evaporator to a water content of 10 wt% or less before use in sample preparation.

[0065] <Measurement of AmSS Charge Amount (Air Feed Method)> A sample was placed in the powder supply section of the charging tube, left for 10 minutes, and then transported with air at a flow rate of 130 L / min. The charge amount on the charging tube side was calculated from the voltage value obtained from the Faraday gauge and the current value obtained from the charging tube. Electrometer: Model 6514 (manufactured by KEITHLEY) Charging tube: SUS, 24.6φ x 500 mm Measurement temperature: 25-26°C (humidity 20-30%) Sample amount: approximately 0.50 g

[0066] <X-ray diffraction (XRD) measurement of AmSS> The compositions obtained in the examples were pulverized in a mortar, and XRD was measured by the following method. All sample preparation and measurement were carried out in an air atmosphere, and the measurement data was analyzed using HighScore Plus XRD analysis software. Apparatus: X-ray analyzer Aeris manufactured by Malvern Panalytical; X-ray source: CuKα1 (1.540 Å), CuKα2 (1.544 Å), Kα2 / Kα1 ratio = 0.5; Output: 40 kV and 7.5 mA; Geometry: Bragg-Brentano method, sample horizontal type (θ-θ); Step size: 0.02° 2θ; Scan step time: 148.9 s; Scan range: Continuous scan from 2θ = 4° (start) to 2θ = 80° (end)

[0067] Example 1: Preparation of AmSS using NaSS and ammonium sulfate (1) 290.00 g of NaSS powder, 3.17 g of 4-methoxyphenol, 185.04 g of ammonium sulfate, and 719.30 g of ion-exchanged water were charged into a cylindrical 2 L glass separable flask equipped with a reflux condenser. A cation exchange reaction was carried out with stirring at an internal temperature of 45°C for 60 minutes using a stirrer. The mixture was then cooled to 25°C over 4 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600 G x 15 minutes, room temperature) to obtain 203.68 g of plate-shaped wet crystals (Figure 3). The slurry had good drainability, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 8.00 wt%. The sodium content of the wet crystals determined by ICP was 0.27% by weight (the theoretical Na content in pure NaSS is 11.1% by weight), and the nitrogen content determined by elemental analysis was 6.7% by weight (the theoretical nitrogen content in pure AmSS is 7.0% by weight). １ The molar ratio of ammonium cations to styrene sulfonic acid units determined by H-NMR was 1.00 (Figure 2) (the theoretical molar ratio of ammonium cations to styrene sulfonic acid units in pure AmSS is 1.00), and therefore the wet crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the AmSS composition determined by redox titration was 90.6 wt% (74% yield based on the molar content of the raw material NaSS). The reaction recipe and results are summarized in Table 1.

[0068] The alkali metal, halogen, and polymer contents in this AmSS composition are lower than those in Comparative Examples 1-2, 4-6, 7, and 11 (Tables 5 and 7) described below, demonstrating a high level of purity. Furthermore, the median diameter of this AmSS was 420 μm, significantly larger than the 11 μm (Table 7) shown in Comparative Example 11, and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, since this AmSS composition contains low moisture and 460 ppm of 4-methoxyphenol, it is clear that it has superior storage stability compared to Comparative Example 3 (Table 5). Furthermore, because it contains low amounts of lithium and nitrite, it is clear that it is less susceptible to discoloration than Comparative Examples 8-10 (Table 6). Furthermore, the charge charge per unit mass of this AmSS composition was 0.083 μC / g, slightly lower than the 0.110 μC / g of Comparative Example 11 (Table 7), which has low moisture content.

[0069]

[0070] Example 2: Preparation of AmSS using NaSS and ammonium sulfate (2) 290.00 g of NaSS powder, 7.00 g of 4-methoxyphenol, 230.00 g of ammonium sulfate, and 750.00 g of ion-exchanged water were charged into a cylindrical 2 L glass separable flask equipped with a reflux condenser. A cation exchange reaction was carried out with stirring at an internal temperature of 45°C for 60 minutes using a stirrer. The mixture was then cooled to 35°C over 30 minutes, held for 10 minutes, and then heated again to an internal temperature of 45°C. When the internal temperature reached 45°C, heating was stopped, the mixture was cooled to 25°C over 4 hours, and aged for 2 hours to obtain a white slurry. Subsequently, the slurry was centrifuged under the same conditions as in Example 1 to obtain 195.36 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content determined with an infrared moisture meter was 7.86 wt%. The sodium content of the wet crystals determined by ICP was 0.27% by weight (the theoretical Na content in pure NaSS is 11.1% by weight), and the nitrogen content determined by elemental analysis was 6.7% by weight (the theoretical nitrogen content in pure AmSS is 7.0% by weight). １The molar ratio of ammonium cations to styrenesulfonic acid units determined by H-NMR was 1.01 (the theoretical molar ratio of ammonium cations to styrenesulfonic acid units in pure AmSS is 1.00), and therefore the wet crystals were determined to be the target AmSS composition.

[0071] The AmSS content, i.e., purity, of the AmSS composition determined by oxidation-reduction titration was 90.8% by weight (71% yield based on the molar content of the raw material NaSS). The reaction recipe and results are summarized in Table 1. The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-6, 7, and 11 (Tables 5 and 7), demonstrating a higher purity. Furthermore, the median diameter of the AmSS was 349 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, the AmSS composition contained less water and 889 ppm of 4-methoxyphenol, demonstrating superior storage stability compared to Comparative Example 3 (Table 5). Furthermore, the lower lithium and nitrite contents made it less susceptible to discoloration compared to Comparative Examples 8-10 (Table 6). The amount of charged charge per unit mass of the AmSS composition was 0.082 μC / g, which was slightly lower than that of Comparative Example 11 (Table 7) which had a low water content.

[0072] Example 3 Production of AmSS using NaSS and ammonium sulfate (3) - Synthesis of AmSS - In Example 1, the feed composition and temperature conditions were changed to those shown in Table 1, and plate-like wet crystals presumed to be AmSS were obtained by the same procedure as in Example 1.

[0073] Based on the analytical results shown in Table 1, the wet crystals were determined to be an AmSS composition. The alkali metal, halogen, and polymer contents in this AmSS composition were lower than those in Comparative Examples 1-2, 4-6, 7, and 11 (Tables 5 and 7), demonstrating high purity. Furthermore, the median diameter of this AmSS was 374 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7). Therefore, dust generation is expected to be lower than that of Comparative Example 11. Furthermore, since this AmSS composition contains 356 ppm of 4-methoxyphenol, it is clear that it has superior storage stability compared to Comparative Example 3 (Table 5). Furthermore, because it contains low amounts of lithium and nitrite, it is clear that it is less likely to discolor than Comparative Examples 8-10 (Table 6). Furthermore, the AmSS composition had a charge per unit mass of 0.082 μC / g, slightly lower than that of Comparative Example 11 (Table 7), which has low water content.

[0074] - Polymerization of AmSS - The radical polymerization of the AmSS composition was confirmed. 10.00 g of the AmSS wet crystals obtained above, 1.00 g of an aqueous polymerization initiator solution (a 1.85 wt % aqueous solution of V-50), and 80.00 g of ion-exchanged water were placed in a 300 ml three-necked flask reactor equipped with a condenser, a magnetic induction stirrer, and a nitrogen inlet tube. The pressure was reduced using an aspirator and nitrogen was introduced repeatedly to deoxygenate the mixture. The reactor was then immersed in a 60°C warm bath, and polymerization was initiated with stirring. Sampling was performed at regular intervals, and the polymerization conversion and molecular weight were measured by GPC. The results shown in Table 2 clearly demonstrate no significant differences in polymerization rate and molecular weight compared to Examples 2 and 4 and Comparative Example 3, which contained a low amount of methoxyphenol.

[0075]

[0076] Example 4: Preparation of AmSS using NaSS and Ammonium Sulfate (4) - Synthesis of AmSS - 290.00 g of NaSS powder, 1.58 g of 4-methoxyphenol, 184.55 g of ammonium sulfate, and 1,450.00 g of ion-exchanged water were charged into a cylindrical 2 L glass separable flask equipped with a reflux condenser. A cation exchange reaction was carried out with stirring at an internal temperature of 45°C for 30 minutes using a stirrer. The mixture was then cooled to an internal temperature of 30°C over 30 minutes to form a slurry. 52.73 g of the AmSS composition obtained in Example 1 was added as seed crystals and stirred for 10 minutes (the ratio of ammonium cations derived from ammonium sulfate to NaSS was 2.25 equivalents, and the total solids content was 25.46 wt%). The mixture was then cooled to 10°C over 3 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged in the same manner as in Example 1 to obtain 239.12 g of plate-shaped wet crystals.

[0077] Based on the analytical results shown in Table 1, the wet crystals were determined to be an AmSS composition. Because the AmSS composition contained 156 ppm of 4-methoxyphenol, it clearly had superior storage stability compared to Comparative Example 3 (Table 5). Furthermore, because it contained less lithium and nitrite, it clearly had less discoloration compared to Comparative Examples 8 to 10 (Table 6). Furthermore, the median diameter of the AmSS was 356 μm, which was significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore, it was expected to have lower dust generation than Comparative Example 11. Furthermore, the charge per unit mass of the AmSS composition was 0.077 μC / g, slightly lower than Comparative Example 11 (Table 7), which contained less water.

[0078] <Polymerization of AmSS Composition> The radical polymerizability of the AmSS composition was confirmed under the same conditions as in Example 3. The results shown in Table 2 clearly show that there is no significant difference in the polymerization rate and molecular weight compared to Examples 2 and 3 and Comparative Example 3, which contains a small amount of methoxyphenol.

[0079] Example 5: Preparation of AmSS using NaSS and ammonium sulfate (5) 423.79 g of NaSS powder, 4.65 g of 4-methoxyphenol, 269.90 g of ammonium sulfate, and 1,048.89 g of ion-exchanged water were charged into a cylindrical 2 L glass separable flask equipped with a reflux condenser. A cation exchange reaction was carried out with stirring at an internal temperature of 45°C for 60 minutes using a stirrer. The mixture was then cooled to 15°C over 5 hours and aged for 2 hours to obtain a white slurry. Subsequently, the slurry was centrifuged (600G x 20 minutes, room temperature) to obtain 320.66 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 5.10 wt%. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 293.35 g of dried crystals. The sodium content of AmSS determined by ICP was 0.21 wt%, the nitrogen content determined by elemental analysis was 6.8 wt% and １The molar ratio of ammonium cations to styrenesulfonic acid units determined by H-NMR was 1.00, and the dried crystals were therefore determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by redox titration was 98.4 wt% (82% molar yield based on the starting NaSS). The reaction recipe and results are summarized in Table 3. Furthermore, the wet crystals exhibited good drying properties, with the moisture content reduced to 0.27 wt% after drying on a rotary evaporator. This drying property remained unchanged even after storing the wet crystals in a sealed container at room temperature for at least six months. On the other hand, the moisture content of the starting NaSS, even when dried under the same conditions, was 3.69 wt%. This means that the moisture content of the wet AmSS crystals was adherent water, and its drying properties were completely different from those of the crystallization water contained in the starting NaSS. Thus, the AmSS composition of the present invention is believed to be stabilized by anhydrous salt crystals. The alkali metal, halogen, and polymer contents in this AmSS composition were clearly lower and of higher purity than those in Comparative Examples 1-2, 4-6, 7, and 11 (Tables 5 and 7) described below. Furthermore, the median diameter of this AmSS was 367 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation was expected to be lower than that of Comparative Example 11. Furthermore, since this AmSS composition contained low moisture and 289 ppm of 4-methoxyphenol, it clearly had superior storage stability compared to Comparative Example 3 (Table 4). Furthermore, because the lithium and nitrite contents were low, it was clearly significantly less susceptible to discoloration than Comparative Examples 8-10 (Table 6). Furthermore, the polymer content was 0.03 wt % after a 60°C storage stability test was extended to at least 210 days, demonstrating extremely high stability. The AmSS composition had a charge quantity per unit mass of 0.093 μC / g, which was higher than those of Examples 1 to 4, but slightly lower than that of Comparative Example 11 (Table 7) which had a smaller particle size.

[0080] In addition, when the PXRD patterns of the wet AmSS obtained in this example, the dry AmSS, and the NaSS used as the raw material were compared (FIGS. 7 to 12), the diffraction patterns of AmSS and NaSS were clearly different. This is thought to be largely due to the difference between NaSS stabilized with hemihydrate crystals and AmSS stabilized with anhydrous salt crystals.

[0081]

[0082] Example 6 Purification of AmSS Composition 132.90 g of the AmSS composition obtained in Example 1, 0.74 g of 4-methoxyphenol, and 85.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser, and the mixture was stirred for 60 minutes at an internal temperature of 55°C using a stirrer. After that, the mixture was cooled to an internal temperature of 35°C over 60 minutes, and then heated again to 45°C. When the internal temperature reached 45°C, heating was stopped, and the mixture was cooled to an internal temperature of 25°C over 4 hours. After aging for 2 hours, the slurry was centrifuged in the same manner as in Example 1 to obtain 95.43 g of AmSS composition.

[0083] As shown in Table 4, the AmSS composition is significantly more purified than Examples 1 to 4 and has superior storage stability compared to Comparative Example 3 (Table 5). Furthermore, due to the low lithium and nitrite content, it is significantly less likely to discolor than Comparative Examples 8 to 10 (Table 6). Furthermore, the median diameter was 278 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), demonstrating low dust generation. The AmSS composition was dried using a rotary evaporator at 40°C for 30 minutes (pressure 665 Pa). The moisture content was excellent, decreasing to 0.31 wt%, and the purity increased to 99.3%. The dried AmSS composition was placed in a glass Petri dish and left in a thermo-hygrostat at 30°C and 75% relative humidity for 24 hours. The moisture content was 0.52 wt%. On the other hand, the same procedure was performed using NaSS with a moisture content of 0.15 wt%, which had been prepared by vacuum drying at 60°C for 12 hours. The moisture content increased to 4.95 wt%. This suggests that NaSS is stabilized by hemihydrate crystals, whereas the AmSS composition of the present invention is stabilized by anhydrous salt crystals. The dried AmSS composition was crushed for 10 seconds at room temperature and 4,000 rpm using a small benchtop power mill (P-02S, manufactured by Showa Chemical Machinery Works, Inc.), resulting in a median diameter of 56 μm. As described above, the crushed material was placed in a glass petri dish and left in a thermo-hygrostat at 30°C and 75% relative humidity for 24 hours. Despite a significant decrease in median diameter, the moisture content only increased to 0.58 wt %. This is because the AmSS composition is stabilized by anhydrous salt crystals.

[0084]

[0085] Comparative Example 1: Production of AmSS using NaSS and ammonium sulfate (6) In Example 4, the production of AmSS was attempted by changing the feed composition and temperature conditions to those shown in Table 5. From the analysis results of the sodium and nitrogen contents in the obtained wet crystals (Table 5), it was determined that the wet crystals were an AmSS composition. However, due to poor drainage of the slurry, the water content of the composition was high at 18.90 wt %, and the purity was low at 77.2%, which was clearly inferior to that of Examples 1 to 4. Despite the presence of 169 ppm of 4-methoxyphenol, the storage stability was clearly inferior to that of Examples 1 to 4. This was due to the high water content, and the increase in water content is thought to be due to the total solids content being too low during the reaction.

[0086] Comparative Example 2: Production of AmSS using NaSS and ammonium sulfate (7) In Example 4, the production of AmSS was attempted by changing the feed composition and temperature conditions to those shown in Table 5. From the analysis results of the sodium and nitrogen contents in the obtained wet crystals (Table 5), it was determined that the wet crystals were an AmSS composition. However, due to poor drainage of the slurry, the water content of the composition was high at 21.00 wt %, and the purity was low at 75.2%, which was clearly inferior to the purity of Examples 1 to 4. Despite the presence of 174 ppm of 4-methoxyphenol, the storage stability was clearly inferior to that of Examples 1 to 4. This was due to the high water content, and the increase in water content is thought to be due to the addition of too much ammonium sulfate to NaSS during the reaction.

[0087] Comparative Example 3: Production of AmSS using NaSS and ammonium chloride (1) In Example 4, the inorganic ammonium salt type, charge composition, and temperature conditions were changed to those shown in Table 5, and an attempt was made to produce AmSS. Based on the analysis results of the sodium and nitrogen contents in the obtained wet crystals (Table 5), the wet crystals were determined to be the AmSS composition. The drainability of the slurry was good, and the water content of the AmSS composition was low at 7.54 wt %, and although the halogen content was somewhat high, the purity was 90.1%, equivalent to that of Examples 1 to 4. However, the storage stability was clearly inferior to that of Examples 1 to 4. This is thought to be due to the fact that, although the water content was low, the 4-methoxyphenol content was too low at 16 ppm.

[0088] Comparative Example 4: Production of AmSS using NaSS and Ammonium Chloride (2) In Example 1, the inorganic ammonium salt type, charge composition, and temperature conditions were changed to those shown in Table 5, and an attempt was made to produce AmSS. Based on the analysis results of the sodium and nitrogen contents in the obtained wet crystals (Table 5), the wet crystals were determined to be the AmSS composition. However, due to poor drainage of the slurry, the composition had a water content of 17.30 wt %, a high halogen content of 2.01 wt %, and a low purity of 80.1%, clearly inferior to those of Examples 1 to 4. This is thought to be due to the reaction temperature being too low. Furthermore, although the 4-methoxyphenol content in the AmSS composition was 78 ppm, the storage stability was significantly inferior to those of Examples 1 to 4. This is thought to be due to the high water content.

[0089] Comparative Example 5: Production of AmSS using NaSS and ammonium chloride (3) In Example 1, the production of AmSS was attempted by changing the inorganic ammonium salt species, charging composition, and temperature conditions to those shown in Table 5. Analysis of the resulting wet crystals revealed that the sodium content was very high at 6.47 wt % and the cation exchange rate was less than 50% (Table 5). This is thought to be because the molar ratio of ammonium cations added to NaSS was too low at 0.96 equivalents.

[0090] Comparative Example 6: Production of AmSS using NaSS and ammonium sulfate (8) - Synthesis of AmSS - In Example 4, the feed composition and temperature conditions were changed to those shown in Table 5, and an attempt was made to produce AmSS. Based on the sodium and nitrogen contents of the resulting wet crystals, the wet crystals were determined to be an AmSS composition (Table 5). The slurry had good drainability, and the AmSS composition had a low water content of 7.75 wt. %, a low halogen content of 0.02 wt. , and a high purity of 90.4%, comparable to that of Example 4. However, due to the increased amount of 4-methoxyphenol added during the reaction, the 4-methoxyphenol content in the AmSS composition increased to 2204 ppm. As a result, the spontaneous polymerization during storage at 60°C was suppressed to the same level as in Examples 1 to 3, but the APHA value increased. Furthermore, as shown in Table 2 and below, adverse effects were observed on the polymerization during polymer production.

[0091] - Polymerization of AmSS - The polymerizability of the AmSS composition was confirmed under the same conditions as in Example 3. As a result, it was clear that the polymerization rate was significantly slower and the molecular weight was lower than in Examples 1 to 4 and Comparative Example 3, which contained less 4-methoxyphenol (Table 2).

[0092] Comparative Example 7: Preparation of AmSS using NaSS and ammonium sulfate (9) In Example 3, the reaction temperature was changed from 60°C to 85°C to attempt the production of AmSS. Based on the analysis of the sodium and nitrogen contents of the resulting wet crystals, the wet crystals were determined to be the AmSS composition (Table 5). However, the drainability of the slurry was poor, and the water content of the AmSS composition was high at 13.70 wt%, resulting in a low purity of 84.3 wt%, clearly inferior to Examples 1 to 4. This is thought to be due to the reaction temperature being too high, which prevented the production of high-quality crystals, and the increased amount of polymer produced, which reduced drainability. Furthermore, although the 4-methoxyphenol content of the AmSS composition was 394 ppm, the high water content resulted in significantly inferior storage stability compared to Examples 1 to 4.

[0093]

[0094] Comparative Example 8: Preparation of AmSS using LiSS and ammonium chloride (1) 541.54 g of LiSS powder, 1.20 g of lithium nitrite (40 wt % aqueous solution), 150.18 g of ammonium chloride, and 1135.09 g of ion-exchanged water were charged into a cylindrical 2 L glass separable flask equipped with a reflux condenser. A cation exchange reaction was carried out with stirring at an internal temperature of 35 ° C for 60 minutes using a stirrer. The mixture was then cooled to 5 ° C over 5 hours. The mixture was then aged for 2 hours to obtain a white slurry. Subsequently, the slurry was centrifuged under the same conditions as in Example 1 to obtain 423.65 g of diamond-shaped plate-shaped wet crystals. The slurry had good drainability, and the moisture content determined by an infrared moisture meter was 9.62 wt %. The lithium content of the wet crystals determined by ICP was 0.13 wt % (the theoretical Li content in pure LiSS is 3.65 wt %), the sodium content was 5 ppm, and the nitrogen content of the AmSS composition determined by elemental analysis was 6.3 wt % (the theoretical nitrogen content in pure AmSS is 7.0 wt %). １The molar ratio of ammonium cations to styrene sulfonic acid units determined by H-NMR was 1.01 (the theoretical molar ratio of ammonium cations to styrene sulfonic acid units in pure AmSS is 1.00), and therefore the wet crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the AmSS composition determined by redox titration was 89.2% (yield based on the raw LiSS molar content was 77%). As summarized in Table 6, the purity of the AmSS composition was equivalent to that of Examples 1 to 4 (Table 1). However, due to the absence of 4-methoxyphenol, the storage stability was significantly inferior to that of Examples 1 to 4.

[0095] Comparative Example 9: Production of AmSS using LiSS and Ammonium Sulfate (2) In Comparative Example 9, AmSS was produced by changing the inorganic ammonium salt species, charge composition, and temperature conditions to those shown in Table 6, and adding 4-methoxyphenol. Based on the lithium content analysis results of the wet crystals, the wet crystals were determined to be an AmSS composition. The drainability of the slurry was good, and the AmSS composition had a low water content of 6.82 wt. %, a low halogen content of 0.09 wt. , and a high purity of 92.5%, comparable to those of Examples 1 to 4. The 4-methoxyphenol content of the AmSS composition was 805 ppm, and spontaneous polymerization during storage at 60°C was suppressed to the same extent as in Examples 1 to 4, but the APHA value increased. While the reason for this is unclear, it is presumed that some interaction between the lithium cation and 4-methoxyphenol is involved. Comparative Example 10: Production of AmSS using LiSS and Ammonium Sulfate (3) In Comparative Example 10, AmSS was produced under the conditions shown in Table 6, except that the type and amount of polymerization inhibitor added were changed. Based on the analysis of the lithium content of the wet crystals, the wet crystals were determined to be an AmSS composition. The drainability of the slurry was good, and the AmSS composition had a low water content of 6.91 wt. %, a low halogen content of 0.08 wt. , and a high purity of 92.6%, comparable to those of Examples 1 to 4. The methoxyphenol content and nitrite content of the AmSS composition were 420 ppm and 72 ppm, respectively. The spontaneous polymerization during storage at 60°C was suppressed to the same extent as in Examples 1 to 4, but the APHA value increased. While the reason for this is unclear, it is presumed that some interaction between the lithium cation, 4-methoxyphenol, and nitrite anion is involved.

[0096]

[0097] Comparative Example 11: Example 1 from JP-A-50-149642. 500.00 g of methanol, 25.01 g of NaSS powder, and 25.02 g of ammonium sulfate were placed in a 1 L four-neck flask equipped with a condenser and heated in a 65°C bath for 3 hours while stirring with a magnetic stirrer. The system was slightly cloudy, and the raw materials were almost completely dissolved (the ratio of ammonium cation to NaSS was 3.54 equivalents, and the total solids content was 8.79 wt%). The mixture was then allowed to cool to 30°C, resulting in the precipitation of a solid believed to be sodium sulfate. The reaction solution was subjected to suction filtration using a circulation aspirator, and the precipitate was then filtered off. The filtrate was then concentrated to dryness using a rotary evaporator at 50°C for 2 hours, yielding 21.53 g of dry powder (Figure 6). The moisture content was 0.50 wt%. The active vinyl groups in the dry powder were then quantified by redox titration. Assuming that the dry powder was AmSS, the purity was 98.0%. However, the sodium content determined by ICP was 5.3% by weight (the theoretical Na content in pure NaSS is 11.1% by weight), and the nitrogen content determined by elemental analysis was 3.4% by weight (the theoretical nitrogen content in pure AmSS is 7.0% by weight). １ The molar ratio of ammonium cations to styrenesulfonic acid units determined by H-NMR was 0.54 (the theoretical molar ratio of ammonium cations to styrenesulfonic acid units in pure AmSS was 1.00 (Figure 5)). Therefore, it was estimated that approximately 50% of the dry powder was NaSS, and the cation exchange rate was approximately 50%.

[0098] Despite the addition of 3.54 equivalents of excess ammonium cations relative to the starting material NaSS, the cation exchange rate was low. This is likely due to insufficient ionic dissociation of each salt in methanol and the modest difference in the solubility of each salt in methanol. Furthermore, even if the impurity NaBr in NaSS is converted to ammonium bromide by cation exchange, bromine cannot be removed because ammonium bromide dissolves in methanol. In fact, the halogen content in the dry powder was 1.27 wt%, more than 15 times higher than in Examples 1 to 4. Despite its low moisture content, the dry powder lacked 4-methoxyphenol, resulting in inferior storage stability compared to Examples 1 to 4. Furthermore, the median diameter of the dry powder was very small at 11 μm, and it was significantly more dusty than Examples 1 to 4. Furthermore, the charge per unit mass of the dry powder was 0.110 μC / g, which is higher than in Examples 1 to 5, suggesting high scatterability and a high risk of dust explosion.

[0099]

[0100] Example 7: Preparation of AmSS using NaSS and Ammonium Sulfate (10) ETPE. 73.01 g of ammonium sulfate and 255.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser and dissolved while stirring and heating to an internal temperature of 40°C. After confirming the dissolution of ammonium sulfate, 115.03 g of NaSS powder and 0.70 g of 4-ethoxyphenol were added to the reactor, and a cation exchange reaction was carried out at an internal temperature of 48°C for 60 minutes with stirring. The mixture was then cooled to 25°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600G x 20 minutes, room temperature) to obtain 82.85 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 5.97 wt%. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 77.82 g of dried crystals (water content 0.41 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 8), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by oxidation-reduction titration was 97.9 wt% (77% yield based on the molar content of the raw NaSS). The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-5, 7, and 11 (Tables 5 and 7), demonstrating a higher purity. Furthermore, the median diameter of the AmSS was 362 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, because the AmSS composition contains little water and 169 ppm of 4-ethoxyphenol, it clearly has superior storage stability compared to Comparative Examples 1 to 4 and Comparative Examples 6 to 7 (Table 5). Furthermore, because it contains little lithium or nitrite, it clearly has far less tendency to discolor compared to Comparative Examples 8 to 10 (Table 6). The AmSS composition also had a charge per unit mass of 0.090 μC / g, slightly lower than Comparative Example 11 (Table 7), which had a smaller particle size.

[0101] Example 8: Preparation of AmSS using NaSS and ammonium sulfate (11) TBC AmSS was prepared under the same conditions as in Example 7, except that the polymerization inhibitor was changed to 4-tert-butylcatechol and the amount added was reduced. As a result, 83.83 g of plate-shaped wet crystals were obtained. The slurry had good drainability, and the moisture content of the wet crystals was 7.16 wt% as determined using an infrared moisture meter. The wet crystals were dried using a rotary evaporator to obtain 77.9 g of dry crystals (moisture content: 0.37 wt%). Based on the analysis of the sodium and nitrogen contents in the dried crystals (Table 8), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by redox titration was 98.0 wt% (yield based on the molar content of the raw NaSS: 77%). The alkali metal, halogen, and polymer contents in this AmSS composition are lower than those in Comparative Examples 1 to 6, 7, and 11 (Tables 5 and 7), demonstrating a high purity. Furthermore, the median diameter of this AmSS was 345 μm, significantly larger than the 11 μm (Table 7) shown in Comparative Example 11. Therefore, dust generation is expected to be lower than that of Comparative Example 11. Furthermore, this AmSS composition contains less water and 38 ppm of 4-tert-butylcatechol, demonstrating superior storage stability compared to Comparative Examples 8 to 10 (Table 6). Furthermore, the AmSS composition contains less lithium and nitrite, and a lower content of 4-tert-butylcatechol, which is prone to discoloration. Therefore, it is less likely to discolor than Comparative Examples 8 to 10 (Table 6). Furthermore, the AmSS composition had a charge per unit mass of 0.091 μC / g, slightly lower than that of Comparative Example 11 (Table 7), which has a smaller particle size.

[0102] Example 9: Preparation of AmSS using NaSS and ammonium sulfate (12)H-TEMPO. AmSS was produced under the same conditions as in Example 8, except that the polymerization inhibitor was changed to 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl. As a result, 85.74 g of plate-shaped wet crystals was obtained. The slurry had good drainability, and the moisture content of the wet crystals was 7.91 wt% as determined using an infrared moisture meter. The wet crystals were dried using a rotary evaporator to obtain 79.28 g of dry crystals (moisture content: 0.40 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 8), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by redox titration was 97.8 wt% (78% molar yield based on the starting NaSS). The alkali metal, halogen, and polymer contents in the AmSS composition are clearly lower and of higher purity than those in Comparative Examples 1-2, 4-5, 7, and 11 (Tables 5 and 7). Furthermore, the median diameter of the AmSS is 350 μm, which is much larger than the 11 μm shown in Comparative Example 11 (Table 7). Therefore, the dust-emission properties are expected to be lower than those of Comparative Example 11. Furthermore, the AmSS composition contains less water and 43 ppm of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, which has high polymerization-inhibiting properties. Therefore, the AmSS composition clearly has superior storage stability compared to Comparative Examples 1-4 and 6-7 (Table 5). Furthermore, the lithium and nitrite contents are low, and the content of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, which causes coloration, is low. Therefore, the AmSS composition is clearly less likely to color than Comparative Examples 8-10 (Table 6). The AmSS composition had a charge quantity per unit mass of 0.091 μC / g, which was slightly lower than that of Comparative Example 11 (Table 7) which had a smaller particle size.

[0103]

[0104] Example 10: Preparation of AmSS using NaSS and Ammonium Nitrate (1) H-TEMPO Ammonium nitrate (89.00 g) and 285.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser and dissolved under stirring while heating to an internal temperature of 40°C. After confirming the dissolution of ammonium nitrate, 115.04 g of NaSS powder and 0.25 g of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl were added to the reactor, and a cation exchange reaction was carried out at an internal temperature of 50°C for 30 minutes with stirring. The mixture was then cooled to 20°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600 G x 20 minutes, room temperature) to obtain 81.75 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 6.55 wt%. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 76.60 g of dried crystals (water content 0.85 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 9), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by oxidation-reduction titration was 96.5 wt% (75% molar yield based on the raw NaSS). The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-5, 7, and 11 (Tables 5 and 7), demonstrating a higher purity. Furthermore, the median diameter of the AmSS was 374 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore, dust generation is expected to be lower than that of Comparative Example 11. Furthermore, because the AmSS composition contains little water and 49 ppm of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, which has high polymerization inhibition ability, it clearly has superior storage stability compared to Comparative Examples 1 to 4 and Comparative Examples 6 to 7 (Table 5). Furthermore, because it contains little lithium or nitrite, it clearly has less tendency to discolor compared to Comparative Examples 8 to 10 (Table 6). The AmSS composition also had a charge density per unit mass of 0.088 μC / g, which was slightly lower than that of Comparative Example 11 (Table 7), which had a smaller particle size.

[0105] Example 11: Preparation of AmSS using NaSS and ammonium nitrate (2) MEPE. 89.00 g of ammonium nitrate and 239.70 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser and dissolved while stirring and heating to an internal temperature of 40°C. After confirming the dissolution of ammonium nitrate, 115.04 g of NaSS powder and 1.20 g of 4-methoxyphenol were added to the reactor, and a cation exchange reaction was carried out at an internal temperature of 55°C for 30 minutes with stirring. The mixture was then cooled to 20°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600 G x 20 minutes, room temperature) to obtain 91.32 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 5.83 wt%. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 86.30 g of dried crystals (water content 0.88 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 9), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by oxidation-reduction titration was 96.7 wt% (84% molar yield based on the raw NaSS). The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-5, 7, and 11 (Tables 5 and 7), demonstrating a high purity. Furthermore, the median diameter of the AmSS was 341 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, because the AmSS composition contains little water and 223 ppm of 4-methoxyphenol, it clearly has superior storage stability compared to Comparative Examples 1 to 4 and 6 to 7 (Table 5). Furthermore, because it contains little lithium or nitrite, it clearly has far less tendency to discolor compared to Comparative Examples 8 to 10 (Table 6). The AmSS composition also had a charge quantity per unit mass of 0.088 μC / g, slightly lower than Comparative Example 11 (Table 7), which had a smaller particle size.

[0106] Example 12: Preparation of AmSS using NaSS and ammonium nitrate (3) MEPE. 103.00 g of NaSS powder, 0.44 g of 4-methoxyphenol, and 142.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser and heated to an internal temperature of 40°C while stirring to form a slurry. An aqueous ammonium nitrate solution (105.00 g of ammonium nitrate dissolved in 150.00 g of ion-exchanged water) heated to 40°C was added to the reactor, and a cation exchange reaction was carried out at an internal temperature of 51°C for 30 minutes with stirring. The mixture was then cooled to 20°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600 G x 20 minutes, room temperature) to obtain 82.11 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals was 7.75 wt% as determined using an infrared moisture meter. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 76.41 g of dried crystals (water content 1.62 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 9), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by oxidation-reduction titration was 94.5 wt% (yield based on the molar content of the raw NaSS: 81%). The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-5, 7, and 11 (Tables 5 and 7), demonstrating a high purity. Furthermore, the median diameter of the AmSS was 390 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, because the AmSS composition contains little water and 280 ppm of 4-methoxyphenol, it clearly has superior storage stability compared to Comparative Examples 1 to 4 and Comparative Examples 6 to 7 (Table 5). Furthermore, because it contains little lithium or nitrite, it clearly has far less tendency to discolor compared to Comparative Examples 8 to 10 (Table 6). The AmSS composition also had a charge quantity per unit mass of 0.084 μC / g, slightly lower than Comparative Example 11 (Table 7), which had a smaller particle size.

[0107] Example 13: Preparation of AmSS using NaSS and ammonium nitrate (4) MEPE. 115.04.00 g of NaSS powder, 0.49 g of 4-methoxyphenol, and 115.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser and heated to an internal temperature of 40°C while stirring to form a slurry. An aqueous ammonium nitrate solution (89.00 g of ammonium nitrate dissolved in 90 g of ion-exchanged water) heated to 40°C was added to the reactor, and a cation exchange reaction was carried out at an internal temperature of 60°C for 60 minutes with stirring. The mixture was then cooled to 20°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600G x 20 minutes, room temperature) to obtain 99.74 g of plate-shaped wet crystals. The slurry had good drainability, and the moisture content of the wet crystals was 7.45 wt% as determined using an infrared moisture meter. The wet crystals were dried using a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 93.48 g of dried crystals (water content 1.31 wt%). Based on the analysis of the sodium and nitrogen contents of the dried crystals (Table 9), the dried crystals were determined to be the target AmSS composition. The AmSS content, i.e., purity, of the dried crystals determined by oxidation-reduction titration was 95.3 wt% (a yield based on the molar content of the raw NaSS of 90%). The alkali metal, halogen, and polymer contents in the AmSS composition were lower than those in Comparative Examples 1-2, 4-5, 6-7, and 11 (Tables 5 and 7), demonstrating a high purity. Furthermore, the median diameter of the AmSS was 386 μm, significantly larger than the 11 μm shown in Comparative Example 11 (Table 7), and therefore dust generation is expected to be lower than that of Comparative Example 11. Furthermore, because the AmSS composition contains little water and 412 ppm of 4-methoxyphenol, it clearly has superior storage stability compared to Comparative Examples 1 to 4 and Comparative Examples 6 to 7 (Table 5). Furthermore, because it contains little lithium or nitrite, it clearly has far less tendency to discolor compared to Comparative Examples 8 to 10 (Table 6). The AmSS composition also had a charge quantity per unit mass of 0.079 μC / g, slightly lower than Comparative Example 11 (Table 7), which had a smaller particle size.

[0108] Comparative Example 12: Preparation of AmSS using NaSS and ammonium nitrate (5) MEPE. 115.01 g of NaSS powder, 1.20 g of 4-methoxyphenol, 89.00 g of ammonium nitrate, and 165.00 g of ion-exchanged water were charged into a cylindrical 0.5 L glass separable flask equipped with a reflux condenser, and a cation exchange reaction was carried out with stirring at an internal temperature of 60°C for 60 minutes. The mixture was then cooled to 20°C over 5 hours and aged for 2 hours to obtain a white slurry. The slurry was then centrifuged (600G x 20 minutes, room temperature) to obtain 110.00 g of plate-shaped wet crystals. However, the slurry had poor drainage properties, and the moisture content of the wet crystals, as determined by an infrared moisture meter, was 15.50 wt%. The wet crystals were dried in a rotary evaporator at 40°C for 30 minutes (pressure 660 Pa), yielding 92.67 g of dried crystals (water content 1.98 wt%). The AmSS content, i.e., purity, of the dried crystals determined by redox titration was 92.7 wt% (yield based on the molar content of the raw NaSS was 95%), but the sodium content determined by ICP was 0.65 wt%, significantly higher than that of Example 13. This was due to the high total solids content during the reaction. The charge per unit mass of the AmSS composition was 0.078 μC / g, slightly lower than that of Comparative Example 11 (Table 7), which had a smaller particle size.

[0109]

[0110] Reference Examples 1 to 4 Filterability of AmSS Solutions The AmSS compositions obtained in Examples 1, 3, and 10, and Comparative Example 11, and N-methylpyrrolidone were placed in a 100-ml stoppered Erlenmeyer flask in the compositions shown in Table 10. The flask was immersed in a 35°C water bath and the AmSS compositions were dissolved using a magnetic stirrer. After visually confirming dissolution, the solution was immediately filtered using a Buchner funnel (quantitative filter paper No. 5A, manufactured by Advantec Toyo Co., Ltd., diameter 70 mm, operating pressure 3.0 kPa), and the filtration time was measured. As shown in Table 10, it is clear that the lower the sodium content, the shorter the filtration time. In other words, a lower content of metals such as sodium is preferable for electronic material applications, but is also advantageous in terms of filterability.

[0111]

Claims

1. An ammonium styrene sulfonate composition having the following characteristics (1) to (6): (1) The content of ammonium styrene sulfonate in the composition is 88.0% by weight or more. (2) The water content in the composition is 10.00% by weight or less. (3) The alkali metal content in the composition is 0.50% by weight or less (however, the lithium content is 20 ppm or less). (4) The halogen content in the composition is 1.00% by weight or less. (5) The polymer content in the composition is 0.20% by weight or less, and (6) The content of polymerization inhibitors in the composition is 2000 ppm or less (however, the content of nitrous acid, a polymerization inhibitor derived from raw materials, is 20 ppm or less).

2. 2. The ammonium styrene sulfonate composition according to claim 1, (1) The content of ammonium styrene sulfonate in the composition is 88.0% by weight or more. (2) The water content in the composition is 0.10% by weight to 10.00% by weight; (3) The alkali metal content in the composition is 0.50% by weight or less (however, the lithium content is 20 ppm or less). (4) The halogen content in the composition is 1.00% by weight or less. (5) The polymer content in the composition is 0.20% by weight or less, and (6) The content of polymerization inhibitor in the composition is 20 ppm to 2000 ppm (however, the content of nitrous acid, a polymerization inhibitor derived from raw materials, is 20 ppm or less). The ammonium styrene sulfonate composition according to claim 1,

3. 2. The ammonium styrene sulfonate composition according to claim 1, (1) The content of ammonium styrene sulfonate in the composition is 94.00% by weight or more; (2) The water content in the composition is 0.10% by weight to 6.00% by weight; (3) The alkali metal content in the composition is 0.50% by weight or less (however, the lithium content is 20 ppm or less). (4) The halogen content in the composition is 0.10% by weight or less; (5) The polymer content in the composition is 0.20% by weight or less, and (6) The content of polymerization inhibitor in the composition is 20 ppm to 1000 ppm (however, the content of nitrous acid, which is a polymerization inhibitor derived from raw materials, is 20 ppm or less). The ammonium styrene sulfonate composition according to claim 1,

4. The polymerization inhibitor is 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,5-dimethoxyphenol, 2,6-dimethoxyphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylcatechol, hydroquinone, methylhydroquinone, 2-methoxyhydroquinone, tert-butylhydroquinone 4. The ammonium styrenesulfonate composition according to claim 1, wherein the ammonium styrenesulfonate is at least one selected from the group consisting of methyl styrene, ammonium N-nitrosophenylhydroxylamine, 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, and salicylic acid hydrazide.

5. The ammonium styrenesulfonate composition according to any one of claims 1 to 3, wherein the polymerization inhibitor is at least one phenolic compound selected from the group consisting of 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 4-ethoxyphenol, 4-cyanophenol, 4-butoxyphenol, 3-ethoxyphenol, 2,5-dimethoxyphenol, and 2,6-dimethoxyphenol.

6. The ammonium styrenesulfonate composition according to any one of claims 1 to 3, wherein the amount of charge per unit mass is 0.020 μC / g to 0.200 μC / g.

7. The ammonium styrenesulfonate composition according to any one of claims 1 to 3, wherein the median diameter of the crystals in the composition is 30 µm to 700 µm.

8. The ammonium styrenesulfonate composition according to any one of claims 1 to 3, wherein the median diameter of the crystals in the composition is 30 µm to 500 µm.

9. 4. The ammonium styrenesulfonate composition according to claim 1, wherein the polymer content in the composition is 0.20% by weight or less when the composition is stored in a sealed state at 60°C for 60 days.

10. Furthermore, when the composition is stored in a sealed state at 60°C for 60 days, the APHA value of a 10 wt% aqueous solution of the composition is 100 or less. The ammonium styrenesulfonate composition according to any one of claims 1 to 3.

11. Furthermore, there is no significant difference in polymerization rate and molecular weight between any two compositions having different polymerization inhibitor contents. The ammonium styrenesulfonate composition according to any one of claims 1 to 3.

12. 4. The ammonium styrenesulfonate composition according to claim 1, wherein the powder X-ray diffraction pattern measured by irradiation with copper Kα X-rays has diffraction peaks at at least diffraction angles 2θ=8.1±0.2°, 15.2±0.2°, 18.4±0.2°, 20.6±0.2°, 24.2±0.2°, 32.5±0.2°, and 43.0±0.2°.

13. 4. The ammonium styrenesulfonate composition according to claim 1, wherein the powder X-ray diffraction pattern measured by irradiation with copper Kα X-rays has diffraction peaks at diffraction angles 2θ=8.1±0.2°, 15.2±0.2°, 15.4±0.2°, 18.4±0.2°, 20.1±0.2°, 20.6±0.2°, 20.8±0.2°, 24.2±0.2°, 25.8±0.2°, 27.5±0.2°, 30.5±0.2°, 32.5±0.2°, 37.5±0.2°, 43.0±0.2°, and 49.6±0.2°.

14. A method for producing a styrenesulfonate product, comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of a polymerization inhibitor in an amount of 7 mol% or less relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, followed by cooling to precipitate ammonium styrenesulfonate crystals, and filtering the crystals; the charge ratio of the ammonium cation to the alkali metal styrenesulfonate is 1.50 equivalents to 3.00 equivalents; The total solid content in the reaction system is 25.00% by weight to 50.00% by weight, The temperature at which sodium or potassium styrenesulfonate is contacted with the inorganic ammonium salt is 30°C to 80°C, and The temperature at which the precipitated crystals are filtered off is 5°C to 30°C. Ammonium styrene sulfonate composition.

15. A method for producing an ammonium styrenesulfonate composition, comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of a polymerization inhibitor in an amount of 7 mol % or less relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, cooling the mixture to precipitate ammonium styrenesulfonate crystals, and filtering out the crystals, the charge ratio of the ammonium cation to the alkali metal styrenesulfonate is 1.50 equivalents to 3.00 equivalents; The total solid content in the reaction system is 25.00% by weight to 50.00% by weight, The temperature at which sodium or potassium styrenesulfonate is contacted with the inorganic ammonium salt is 30°C to 80°C, and The method for producing an ammonium styrenesulfonate composition according to any one of claims 1 to 3, wherein the temperature for filtering the precipitated crystals is 5°C to 30°C.

16. The method for producing the ammonium styrene sulfonate composition according to claim 15, A method for producing an ammonium styrenesulfonate composition, comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of a polymerization inhibitor in an amount of 7 mol % or less relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, cooling the mixture to precipitate ammonium styrenesulfonate crystals, and filtering out the crystals, the charge ratio of the ammonium cation to the alkali metal styrenesulfonate is 1.50 equivalents to 3.00 equivalents; The total solid content in the reaction system is 25.00% by weight to 45.00% by weight, The temperature at which sodium or potassium styrenesulfonate is contacted with the inorganic ammonium salt is 30°C to 80°C, and A method for producing an ammonium styrenesulfonate composition, wherein the temperature for filtering the precipitated crystals is 5°C to 30°C.

17. The method for producing the ammonium styrene sulfonate composition according to claim 15, A method for producing an ammonium styrenesulfonate composition, comprising contacting sodium or potassium styrenesulfonate with an inorganic ammonium salt in water in the presence of 5 mol % or less of a polymerization inhibitor relative to the amount of sodium or potassium styrenesulfonate to cause a cation exchange reaction, cooling the mixture to precipitate ammonium styrenesulfonate crystals, and filtering out the crystals, the charge ratio of the ammonium cation to the alkali metal styrenesulfonate is 2.00 equivalents to 2.50 equivalents; The total solid content in the reaction system is 35.00% by weight to 45.00% by weight, The temperature at which the sodium or potassium styrenesulfonate is contacted with the inorganic ammonium salt is 40°C to 60°C, and A method for producing an ammonium styrenesulfonate composition, wherein the temperature at which the precipitated crystals are filtered off is 15°C to 25°C.

18. 16. The method for producing an ammonium styrenesulfonate composition according to claim 15, wherein the inorganic ammonium salt is at least one compound selected from the group consisting of ammonium chloride, ammonium sulfate, ammonium nitrate, and ammonium acetate.