High-purity 4-(2-bromoethyl)benzenesulfonic acid and high-purity styrenesulfonic acids derived therefrom, their polymers, and methods for producing the same.

Abstract

This invention provides high-purity styrene sulfonic acids and their polymers, which have significantly reduced binding bromine content and are particularly useful as components for electronic materials, such as modifiers for secondary batteries, dopants for conductive polymers, additives for semiconductor polishing agents and cleaning agents, organic EL elements, and photoresists. [Solution] High-purity 4-(2-bromoethyl)benzenesulfonic acid with reduced nuclear brominates, and high-purity styrenesulfonic acids and polymers thereof derived from high-purity 4-(2-bromoethyl)benzenesulfonic acid with significantly reduced bound bromine.

Description

[Technical Field]

[0001] The present invention relates to high-purity 4-(2-bromoethyl)benzenesulfonic acid with reduced nuclear brominates, high-purity styrenesulfonic acids derived therefrom with reduced bound bromine, and polymers thereof, as well as a method for producing the same. [Background technology]

[0002] Styrene sulfonic acids and polystyrene sulfonic acids derived therefrom are functional monomers and polymers used in fuel cell membranes, polymer solid electrolytes and additives for secondary batteries, dispersants and dopants for conductive polymers and carbon nanotubes, semiconductor cleaning agents, electron-accepting materials and thermoacid generators for organic EL devices, and thermoacid generators and protective films for photoresists (see, for example, Patent Documents 1-5). Because they are mainly used in the field of electronic materials, high-purity styrene sulfonic acids and polymers with impurities such as halogens that cause metal corrosion reduced as much as possible are required (see, for example, Patent Document 6).

[0003] Among styrene sulfonic acids, styrene sulfonic acid esters are oil-soluble liquid monomers, and are highly valuable for the above-mentioned applications because they can be easily copolymerized with oil-soluble monomers or used in coating processes to form polymer coatings on various substrate surfaces or to manufacture polymer electrolyte membranes. Furthermore, styrene sulfonates such as styrene sulfonate amine salts and lithium salts have high solubility in water and aprotic polar solvents, making them applicable to coating processes, and they are highly valuable because they allow for the production of polystyrene sulfonic acid aqueous solutions without the use of organic solvents (see, for example, Patent Document 7). Styrene sulfonate esters can be produced by the following method (for example, Non-Patent Document 1): Specifically, a styrene sulfonate salt such as sodium styrene sulfonate is reacted with thionyl chloride to form styrene sulfonyl chloride, and then esterified using a base such as potassium hydroxide and an alcohol.

[0004] [ka]

[0005] One application of polymerizable styrene sulfonic acid esters, which are vinyl monomers, is polystyrene sulfonic acid with a controlled molecular weight distribution for producing aqueous colloids of conductive polymers (for example, Patent Document 2). For example, it has been reported that an aqueous solution of polystyrene sulfonic acid can be produced by living radical polymerization of ethyl styrene sulfonate, followed by hydrolysis of the ester group with sodium hydroxide, and then removal of metal cations, low molecular weight impurities, and unreacted monomers using a cation exchange resin and an ultrafiltration membrane.

[0006] [ka]

[0007] Polystyrene sulfonic acid can also be produced by other methods. For example, sodium styrene sulfonate The lium was radically polymerized in water, sodium hydroxide was added and the mixture was heated at 60°C, and then the top Similarly, by purification using cation exchange resin and ultrafiltration membrane, polystyrene It has been reported that an aqueous solution of ruhonic acid can be produced (for example, Patent Document 7).

[0008] [ka]

[0009] Polystyrene sulfonic acid can also be produced by another method, namely, with respect to a sulfonating agent. This is a method for sulfonating polystyrene in an inert solvent (for example, Patent Document 8). The manufacturing method has the advantage of making it difficult for alkali metal halides to be mixed in, but the polymer composition and composition There are disadvantages such as limited freedom in polymer design, including the amount of polymer molecules, and a tendency for branched structures to form. be. [Prior art documents]

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Non-Patent Documents

[0011]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] As described above, conventionally, high purity styrenesulfonic acids and their polymers with extremely reduced halogen impurities have been required, and reduction of halogen impurities has been a problem.

[0013] Patent Document 7 discloses polystyrene sulfonic acid having a number-average molecular weight of 50,000 to 1,000,000, a total residual amount of bromine and chlorine of 500 ppm (by mass) or less, and a residual amount of styrene sulfonic acid monomer of 1% by mass or less. After polymerizing sodium styrene sulfonate, the obtained sodium polystyrene sulfonate is treated with an alkali such as ammonia or sodium hydroxide to liberate bromine and chlorine, which are then removed by ethanol precipitation or ultrafiltration to obtain an aqueous solution of sodium polystyrene sulfonate (claim 1 and paragraph 0030). However, there is no specific description regarding the source of bromine and chlorine, and these remain unclear.

[0014] When polystyrene sulfonic acid is prepared using the same method as described above, and the halogen concentration in the aqueous solution is analyzed by ion chromatography, it is indeed possible to seemingly achieve a bromide ion concentration of less than 1 ppm in a fresh aqueous solution immediately after production. However, when the inventors investigated the long-term stability of the polystyrene sulfonic acid aqueous solution in detail, it was found that the bromide ion concentration in the aqueous solution increased significantly over time even under mild conditions, indicating that there were still problems. In other words, the presence of unstable bound bromine that could not be removed by the above purification method and had not been previously reported was suggested. It has been difficult to elucidate the cause of the increase in bromide ion concentration over time and to obtain polystyrene sulfonic acid that can be stored for a long period of time.

[0015] Regarding the bound bromine in sodium styrenesulfonate, the presence of sodium bromostyrenesulfonate has been reported (e.g., International Publication No. WO2014 / 061357). This patent discloses high-purity sodium styrenesulfonate with a sodium bromostyrenesulfonate content of 0.01% (area basis as measured by high-performance liquid chromatography) (paragraph 0080 of the patent publication).

[0016] Specifically, Example 2 of the patent publication in question describes the production of high-purity parastyrene sulfonate sodium, PSS sodium, and evaluation example 2 as a synthetic adhesive for garment ironing. The relative values ​​of the peak areas of each compound measured by the high-performance liquid chromatography method described below are as follows: (a) orthostyrene sulfonate sodium, (b) β-bromoethylbenzene sulfonate sodium, (c) metastyrene sulfonate sodium, (d) bromostyrene sulfonate sodium, and (e) β-hydroxyethylbenzene sulfonate sodium. <Manufacturing of high-purity sodium parastyrene sulfonate> In a stainless steel reactor equipped with a jacket and stirrer, 1,000 g of high-purity sodium parastyrene sulfonate obtained in Example 1, 1 g of sodium nitrite, 20 g of caustic soda, and 950 g of pure water were charged and stirred at 60°C for 1 hour under a nitrogen atmosphere. After cooling to room temperature over 3 hours, solid-liquid separation was performed using a centrifuge to obtain 899 g of a wet cake of high-purity sodium parastyrene sulfonate. The purity of the above high-purity sodium parastyrene sulfonate was 89.1 wt%, the moisture content was 8.2 wt%, the iron content was 0.58 μg / g, the sodium bromide content was 0.20 wt%, and the organic impurities such as isomers were (a) 0.05%, (b) 0.00%, (c) 1.34%, (d) 0.01%, and (e) 0.01%. The median diameter of the above sodium parastyrene sulfonate was 63 μm, small particles less than 10,000 μm accounted for 2.0%, the angle of repose was 49 degrees, and the dissolution time in water was 155 seconds. The above sodium parastyrene sulfonate had a WI value of 95.5, a YI value of 2.9, and an APHA value of 15 wt% aqueous solution of 15 wt%, showing a clearly superior hue compared to the conventional product (Comparative Example 1). Furthermore, although the reason is unclear, it is evident that even with the same iron content as in Example 1, the hue is further improved by reducing impurities such as sodium bromide and isomers.

[0017] The problem to be solved in this patent is the improvement of the hue of sodium parastyrene sulfonate and PSS sodium (polystyrene sulfonate), and the hue is improved by a synergistic effect achieved by simultaneously reducing the iron content and various organic impurities that may be present in sodium parastyrene sulfonate. Specifically, the method involves removing the iron content in an aqueous solution of 4-(2-bromoethyl)benzenesulfonic acid, which is a precursor of sodium parastyrene sulfonate, by cation exchange treatment, and then removing organic impurities by recrystallizing and purifying the obtained sodium parastyrene sulfonate. However, there is no mention of the effect of sodium bromostyrene sulfonate on the hue. On the other hand, the problem to be solved in this invention is the reduction of halogen impurities, which is strongly desired in the field of electronic materials, and in particular, the reduction of organic halogen impurities, i.e., bonded halogens, which are difficult to remove. Indeed, the above-mentioned patent document appears to show that the amount of bound halogens is reduced by reducing the amount of sodium bromostyrene sulfonate. However, when the inventors analyzed the total halogen content in the high-purity sodium styrene sulfonate using combustion decomposition ion chromatography and other methods, they detected a bromine content exceeding 400 ppm, which is at least 10 times higher than the estimated value from the above-mentioned high-performance liquid chromatography method. Therefore, when they actually prepared an aqueous solution of polystyrene sulfonic acid from the high-purity sodium styrene sulfonate and investigated its stability, they found that the bromine ion concentration increased significantly over time. Therefore, there was a need for high-purity styrene sulfonic acids and their polymers with the least amount of unstable bound bromine, as well as methods for producing them. To achieve this, it is necessary to examine in detail not just the bromine content, but also the chemical structure in which bound bromine and other bromine components are included in the process.

[0018] The present invention has been made in view of the above-mentioned problems, and its object is to provide styrene sulfonic acids and polymers thereof in which unstable bound bromine is reduced, as well as methods for producing them. [Means for solving the problem]

[0019] To address the above issues, we focused on 4-(2-bromoethyl)benzenesulfonic acid (hereinafter sometimes abbreviated as BEBS), a precursor of styrenesulfonic acids, and conducted intensive research. As a result, we discovered that BEBS contains nuclear brominated BEBS products (hereinafter sometimes abbreviated as nuclear brominated BEBS), including 2-bromo-4-(2-bromoethyl)benzenesulfonic acid, a compound not previously reported, as an impurity. Furthermore, we found that by controlling the concentrations of iron, hydrogen bromide, and water present in the reaction system to a certain level or lower, and by performing the sulfonation reaction using a specific concentration of the sulfonating agent and a molar ratio of the sulfonating agent to BEBS, it is possible to produce high-purity BEBS with a low content of nuclear brominated BEBS without impairing productivity. Moreover, we found that the styrenesulfonic acids derived from this high-purity BEBS and the bound bromine in their polymers can be significantly reduced, thus completing the present invention.

[0020] In other words, if we can determine at what stage and in what form the bound bromine in styrenesulfonic acids (and their polymers) is generated during the process of producing styrenesulfonic acids from styrene, we can find conditions to suppress its generation. The following shows the reaction process from styrene to sodium styrenesulfonate via 2-bromoethylbenzene and 4-(2-bromoethyl)benzenesulfonic acid. Initially, it was thought that in the reaction step where 4-(2-bromoethyl)benzenesulfonic acid is vinylinated (de-NaBr) by adding an alkali such as NaOH at a high temperature of 70°C to 90°C, the liberated bromine generates bound bromine in styrenesulfonic acids (and their polymers). However, through our investigations, we have found that at least 2-bromoethylbenzene is sulfonated to produce 4-(2-bromoethyl)benzenesulfonic acid, and that bound bromine (in this case, nuclear brominated BEBS) is generated in this process. Therefore, in this invention, we believe that by determining what kind of molecule structure is generated as bound bromine and at what stage that molecule is generated, it is possible to suppress the contamination of styrene sulfonic acids (and their polymers), and this led to the present invention.

[0021] [ka]

[0022] The nuclear brominated BEBS referred to here is a BEBS in which at least one bromine atom is bonded to the benzene ring via a covalent bond (see general formula (1) below), for example, the one shown in general formula (1') below, in which one bromine atom is bonded to the benzene ring. Here, there are no particular restrictions on the position in which the bromine atom is bonded to the benzene ring; for example, when one bromine atom is bonded to the benzene ring, 2-bromo-4-(2-bromoethyl)benzenesulfonic acid, as shown in Figure 1 later, can be cited. Furthermore, bonded bromine refers to bromine bonded via covalent bonds to styrene sulfonic acids having polymerizable vinyl groups, and includes at least one bromine bonded to the benzene ring of the styrene sulfonic acid (see general formula (2) below). For example, a bromine bonded to a single benzene ring is represented by the general formula (2') below. Here, the position of the bromine atom bonded to the benzene ring is not particularly limited; for example, when one bromine atom is bonded to the benzene ring, 2-bromo-4-styrene sulfonic acid is an example. By reducing the amount of fully bound bromine, the unstable bromine content, which had been a problem, has been reduced. [ka] (In equation (1), n ​​is an integer between 1 and 3.) [ka] [ka] (In formula (2), R 1 (This is the same as the definition of the general formula (B) below, where n is an integer from 1 to 3.) [ka] (In formula (2'), R 1 (This is the same as the definition of the general formula (B) below.)

[0023] In other words, the present invention relates to the following invention. [1] High-purity 4-(2-bromoethyl)benzenesulfonic acid in which the amount of nuclear brominated 2-bromoethylbenzenesulfonic acid represented by the following general formula (A) relative to 4-(2-bromoethyl)benzenesulfonic acid is 0.10% or less [however, this is the peak area % determined by liquid chromatography (LC), and is the peak area % of nuclear brominated 2-bromoethylbenzenesulfonic acid when the peak area of ​​4-(2-bromoethyl)benzenesulfonic acid is set to 100%]. [ka] [2] The high-purity 4-(2-bromoethyl)benzenesulfonic acid according to item [1], wherein the nuclear brominated 2-bromoethylbenzenesulfonic acid is 2-bromo-4-(2-bromoethyl)benzenesulfonic acid. [3] The high-purity 4-(2-bromoethyl)benzenesulfonic acid according to item [1] or item [2], wherein the purity of the 4-(2-bromoethyl)benzenesulfonic acid determined by liquid chromatography (LC) is 93 area% or more. [4] A method for producing 4-(2-bromoethyl)benzenesulfonic acid according to any one of items [1] to [3], comprising continuously supplying anhydrous sulfuric acid or an organic solvent solution of 2-bromoethylbenzene and anhydrous sulfuric acid or an organic solvent solution of anhydrous sulfuric acid to a reactor, wherein the iron content in 2-bromoethylbenzene and the organic solvent is controlled to 5 μg / g or less each, the hydrogen bromide to 100 ppm or less each, and the water content to 1000 ppm or less each, the weight percentage of anhydrous sulfuric acid supplied to the total reaction solution in the reactor is maintained at 5.00 wt% to 20.00 wt%, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene in the reactor is maintained at 0.50 to 2.00. [5] A method for producing 4-(2-bromoethyl)benzenesulfonic acid according to any one of items [1] to [3], comprising continuously supplying anhydrous sulfuric acid or an organic solvent solution of anhydrous sulfuric acid to 2-bromoethylbenzene or an organic solvent solution of 2-bromoethylbenzene, wherein the iron content in 2-bromoethylbenzene and the organic solvent is controlled to be 5 μg / g or less each, the hydrogen bromide to be 100 ppm or less each, and the water content to be 1000 ppm or less each, the weight percentage of anhydrous sulfuric acid supplied to the total reaction solution in the reactor is maintained to be 20.00% by weight or less, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene in the reactor is maintained to be 2.00 or less. [6] The method for producing organic solvents according to item [4] or item [5], wherein the organic solvent is one or more organic solvents selected from the group consisting of halogenated solvents, nitrating solvents and aliphatic hydrocarbons. [7] The method for producing sulfuric acid according to any one of items [4] to [6], wherein the sulfuric acid anhydrous is sulfuric acid anhydrous containing 5% to 10% by weight of acetic acid or acetic anhydrous relative to the sulfuric acid anhydrous. [8] The method of production according to any one of items [4] to [7], wherein the anhydrous sulfuric acid or an organic solvent solution of anhydrous sulfuric acid is continuously supplied over a period of 0.5 to 7 hours. [9] The method of production according to any one of items [4] to [8], wherein the reaction temperature is 10 to 60°C and the reaction time is 0.5 to 10 hours.

[10] The method of production according to any one of items [4] to [9], wherein the reaction is performed by continuously withdrawing the reaction solution.

[11] High-purity styrene sulfonic acids represented by the following general formula (B), wherein the bound bromine content determined by combustion decomposition ion chromatography (CIC) is 400 ppm or less. [ka] [In the formula, R 1 [This represents the following general formula (C), the following general formula (D), an amino group, or a chlorine atom.] [ka] [In the formula, R 2 This represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a hydrogen atom, an alkali metal, a substituted or unsubstituted ammonium cation, or a substituted or unsubstituted phosphonium cation. [ka] [In the formula, R 3 R represents a substituted or unsubstituted alkyl group, hydrogen atom, alkali metal, or substituted or unsubstituted ammonium cation. 4 This represents a trifluoromethylsulfonyl group, a perfluorobutylsulfonyl group, a fluorosulfonyl group, a trifluoromethylacetyl group, or a 4-ethenylphenylsulfonyl group. Note that in general formula (B), R 1 In the case of an amino group, the amino group may be a primary, secondary, tertiary, or quaternary amino group, except for the group of general formula (D).

[12] Styrene sulfonic acids represented by the following general formula (B') include sodium 4-styrenesulfonate, lithium 4-styrenesulfonate, potassium 4-styrenesulfonate, ammonium 4-styrenesulfonate, N,N-dimethylcyclohexylamine 4-styrenesulfonate, trioctylamine 4-styrenesulfonate, 4-styrenesulfonyl chloride, 4-styrenesulfonamide, ethyl 4-styrenesulfonate, neopentyl 4-styrenesulfonate, 4-styrenesulfonyl (trifluoromethylsulfonylimide), 4-styrenesulfonyl (perfluorobutylsulfonylimide), 4-styrenesulfonyl (fluorosulfonylimide), or lithium bis-(4-styrenesulfonyl) High-purity styrene sulfonic acids, which are mids and have a bound bromine content of 400 ppm or less as determined by combustion decomposition ion chromatography (CIC). [ka] (In formula (B'), R 1 (This is the same as the definition of the general formula (B) above.)

[13] A method for producing styrenesulfonic acids, which uses the high-purity 4-(2-bromoethyl)benzenesulfonic acid described in item [1] or the high-purity 4-(2-bromoethyl)benzenesulfonic acid obtained by the production method described in item [4] or item [5], and is a method for producing high-purity styrenesulfonic acids described in item

[11] or item

[12] .

[14] Polystyrenesulfonic acids having the following repeating structural unit (E) or polystyrenesulfonic acids having the following repeating structural unit (E) and the following repeating structural unit (F), wherein the bromine ion concentration in the aqueous solution when a 10% by weight aqueous solution of the polystyrenesulfonic acids is maintained at 70 °C for 20 days is 30 ppm or less, and the polystyrenesulfonic acids with reduced bound bromine. [Chemical formula] [In the formula, R 1 is the same as R in the general formula (B) described in

[11] above. 1 [Same as above.]] [Chemical formula] [In the formula, Q represents a repeating structural unit derived from a vinyl monomer copolymerizable with styrenesulfonic acids.]]

[15] The polystyrenesulfonic acids described in item

[14] , wherein the number average molecular weight of the polystyrenesulfonic acids is 500 to 5,000,000.

[16] The polystyrenesulfonic acids described in item

[14] or item

[15] , wherein Q in the repeating structural unit (F) contains a repeating structural unit derived from a vinyl monomer which is one or a combination of two or more selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid ester, (meth)acrylamide, N-substituted maleimide, styrenes and vinylpyridine.

[17] The polystyrenesulfonic acids described in any one of items

[14] to

[16] , wherein Q in the repeating structural unit (F) contains a repeating structural unit derived from a crosslinkable monomer which is one or a combination of two or more selected from the group consisting of substituted styrenes, (meth)acrylic acid esters, (meth)acrylamides and N-substituted maleimides.

[18] A method for producing polystyrene sulfonic acids, comprising polymerizing high-purity styrene sulfonic acids described in item

[11] or high-purity styrene sulfonic acids obtained by the method described in item

[13] , as described in any of items

[14] to

[17] .

[19] Polystyrene sulfonic acids as described in any of items

[14] to

[17] , wherein the bromide ion concentration in a 10% by weight aqueous solution is 10 ppm or less when the aqueous solution is held at 70°C for 20 days.

[20] A method for producing polystyrene sulfonic acids as described in item

[19] , characterized by chemically treating the polystyrene sulfonic acids described in items

[14] to

[17] by the following step (i) or (ii). (i) A step of adding an alkali or an alkali and a reducing agent to the solution of polystyrene sulfonic acid, heating it at 90°C to 110°C for 5 to 30 hours while maintaining the solution pH ≥ 13, and then purifying the polymer. (ii) A step of adding a reducing agent and a palladium catalyst to the polystyrene sulfonic acid solution and heating it at 80°C to 110°C for 5 to 30 hours, followed by purification of the polymer.

[21] An aqueous composition of polystyrene sulfonic acid, wherein the content of polystyrene sulfonic acid described in item

[14] or item

[19] , or polystyrene sulfonic acid obtained by the manufacturing method described in item

[18] , is 1% to 60% by weight, and the content of a phenolic antioxidant relative to the pure content of the polystyrene sulfonic acid is 20 ppm to 2,000 ppm.

[22] The aqueous polystyrene sulfonic acid composition according to item

[21] , wherein the phenolic antioxidant is at least one selected from the group consisting of 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylcatechol, hydroquinone, and methoxyhydroquinone. [Effects of the Invention]

[0024] The high-purity 4-(2-bromoethyl)benzenesulfonic acid and the high-purity styrenesulfonic acids derived therefrom, as well as their polymers, of the present invention have fewer bound bromine molecules, such as nuclear brominated compounds, than conventional materials, and the release of bromine over time is suppressed. Therefore, they are extremely useful in electronic materials applications such as secondary batteries, capacitors, polymer solid electrolytes, conductive polymers, organic EL elements, photoresists, and semiconductor cleaning agents. [Brief explanation of the drawing]

[0025] [Figure 1] The HPLC chart (enlarged view) of the BEBS aqueous solution obtained by the conventional method described in Comparative Example 4 shows the elution time (minutes) on the horizontal axis and the peak intensity (mV) on the vertical axis. In the figure, (A) shows the peak for 4-(2-hydroxyethyl)benzenesulfonic acid, (B) shows the peak for the para-isomer of BEBS, (C) shows the peak for the ortho-isomer of BEBS, (D) shows the peak for 4-(1-bromoethyl)benzenesulfonic acid, and (E) shows the peak for 2-bromo-4-(2-bromoethyl)benzenesulfonic acid (nuclear brominated BEBS). [Figure 2] Figure 2 shows an HPLC chart (enlarged view) of the BEBS aqueous solution obtained by the method of the present invention described in Example 1. The horizontal axis represents elution time (minutes), and the vertical axis represents peak intensity (mV). The symbols (A) to (E) in Figure 2 are the same as those explained in Figure 1. [Figure 3] Figure 1 shows the proton nuclear magnetic resonance spectrum of the sodium salt with impurity peak (E). The horizontal axis represents the chemical shift (ppm), the integers near each peak indicate the type of carbon shown as a number in the chemical structure of sodium 2-bromo-4-(2-bromoethyl)benzenesulfonate shown in the figure, and the two-digit decimal values ​​near each peak indicate the integral ratio of protons bonded to that carbon. [Figure 4] Figure 1 shows the TOF-MS spectrum of the impurity peak (E), with the horizontal axis representing the mass-to-charge ratio m / z (where m is the molecular mass and z is the number of charges) and the vertical axis representing the signal intensity. The left-hand side of Figure 4 shows the mass-to-charge ratio, estimated elemental composition, estimated structure, and desorbed ion species determined by mass spectrometry, while the right-hand side of Figure 4 is a magnified view of the TOF-MS spectrum. [Figure 5] This is an HPLC chart (enlarged view) of high-purity sodium styrenesulfonate prepared using BEBS synthesized by the conventional method, as described in Comparative Example 8. The horizontal axis represents elution time (minutes), and the vertical axis represents peak intensity (mV). The peaks or peak positions indicated by the peaks or arrows in the figure are (a) sodium orthostyrenesulfonate, (b) sodium 4-(2-bromoethyl)benzenesulfonate, (c) sodium metastyrenesulfonate, (d) sodium bromostyrenesulfonate, and (e) peaks or peak positions that are presumed to be derived from sodium 4-(2-hydroxyethyl)benzenesulfonate. [Figure 6] This is an HPLC chart (enlarged view) of high-purity sodium styrenesulfonate prepared using BEBS synthesized by the method of the present invention as described in Example 12. The horizontal axis represents elution time (minutes), and the vertical axis represents peak intensity (mV). The symbols (a) to (e) in Figure 6 are the same as those explained in Figure 5. [Modes for carrying out the invention]

[0026] This invention relates to high-purity BEBS in which the amount of nuclear brominated BEBS that may be contained as an impurity is 0.10% or less (however, this is the area percentage determined by liquid chromatography (LC), and the peak area percentage of nuclear brominated BEBS when the peak area of ​​4-(2-bromoethyl)benzenesulfonic acid is set to 100%), high-purity styrenesulfonic acids and their polymers derived from high-purity BEBS in which the amount of bound bromine derived is 400 ppm or less, and a method for producing them. The present invention was reached after discovering that unstable bound bromine that may be present in styrenesulfonic acids can be reduced by reducing the total bound bromine of the styrenesulfonic acids. Furthermore, "area % determined by liquid chromatography (LC)" refers to the peak area of ​​nuclear brominated 2-bromoethylbenzenesulfonic acid expressed as a percentage when 4-(2-bromoethyl)benzenesulfonic acid is measured by liquid chromatography (LC), such as high-performance liquid chromatography (HPLC), with the peak area of ​​the target 4-(2-bromoethyl)benzenesulfonic acid set to 100%. Therefore, "nuclear brominated BEBS is 0.10% or less" means that the peak area of ​​nuclear brominated 2-bromoethylbenzenesulfonic acid is 0.10% or less when the peak area of ​​4-(2-bromoethyl)benzenesulfonic acid is set to 100%. In other words, when comparing the peak areas, it means that it is 1 / 1000 or less of that of 4-(2-bromoethyl)benzenesulfonic acid.

[0027] The reduction of unstable bound bromines among the above-mentioned bound bromines was confirmed, as described above, by deriving styrene sulfonic acids to an aqueous solution of polystyrene sulfonic acid and tracking the change in bromine ion concentration.

[0028] <4-(2-bromoethyl)benzenesulfonic acid (BEBS)> First, the method for producing BEBS with reduced nuclear brominated BEBS according to the present invention will be described. The basic process for producing BEBS is the same as before, by sulfonation of 2-bromoethylbenzene (see, for example, Japanese Patent Publication No. 55-21030), and 2-bromoethylbenzene is produced by bromination of styrene (see, for example, Japanese Patent Application Publication No. 6-172232). Specifically, as shown in the reaction equation below, styrene is prepared by dissolving it in hydrocarbons such as hexane or halogenated hydrocarbons such as perchloroethylene. Hydrogen bromide gas is supplied to this styrene while irradiating it with ultraviolet light or while supplying a small amount of radical generating agent such as an azo compound, causing the hydrogen bromide to undergo anti-Markovnikov addition to the vinyl group of styrene. This reaction yields 2-bromoethylbenzene. Subsequently, in an acid-resistant, dry reactor, 2-bromoethylbenzene is sulfonated using a sulfonating agent such as anhydrous sulfuric acid (sulfur trioxide), fuming sulfuric acid, concentrated sulfuric acid, or chlorosulfuric acid to obtain 4-(2-bromoethyl)benzenesulfonic acid.

[0029] [ka]

[0030] Herein, the present invention is characterized by the following points (i) to (iv) and differs from conventional methods. (i) Control the levels of 2-bromoethylbenzene and hydrogen bromide, which may be present in the reaction solvent, to 100 ppm or less each. (ii) Control the levels of 2-bromoethylbenzene and iron, which may be present in the reaction solvent, to 5 ppm or less. (iii) Control the water content of 2-bromoethylbenzene and the reaction solvent to 1000 ppm or less each. (iv) Controlling the concentration of the sulfonating agent supplied to the reactor and the molar ratio of the sulfonating agent to 2-bromoethylbenzene within a specific range. If these conditions are not met, nuclear brominated products may be more likely to be produced as by-products, resulting in an increase in the amount of bromine bound to styrene sulfonic acids derived from the nuclear brominated products.

[0031] Hydrogen bromide that may be present in 2-bromoethylbenzene is thought to be unreacted hydrogen bromide used as a raw material in the manufacturing process. It can be controlled to below 100 ppm by heating 2-bromoethylbenzene, heating under reduced pressure, bubbling with an inert gas, washing with pure water, weakly alkaline water, or saline solution, and / or distillation removal along with unreacted styrene and reaction solvent. It is generally unlikely that fresh reaction solvents such as reagents would contain hydrogen bromide. However, in manufacturing facilities such as chemical plants that practically produce the target product, unreacted raw materials and reaction solvents are reused (recycled), and hydrogen bromide may be present in these. Therefore, when using recycled reaction materials and reaction solvents, the hydrogen bromide content should be analyzed and controlled to below 100 ppm using the same method as described above.

[0032] The iron content that may be present in the reaction system is thought to be iron(III) bromide resulting from the hydrogen bromide and moisture in the reaction system as described above, but its structure is uncertain. The iron content is controlled to 5 ppm or less each, preferably 1 ppm or less each, by washing with 2-bromoethylbenzene or the reaction solvent, distillation purification, and / or treatment with cation exchange resin (e.g., Amberlite® from Organo Corporation), chelate fibers (e.g., Kirest Fiber® from Kirest Corporation), cation exchange filters (e.g., Kitz Microfilters Co., Ltd.'s Krangraft), activated carbon (e.g., Seitz AKSJ® from Osaka Gas Chemical Co., Ltd.).

[0033] Furthermore, the water that may be present in the reaction solvent with 2-bromoethylbenzene is water-washed 2-bromoethylbenzene and originates from the reaction solvent used for recycling. Since this water has a particularly strong effect on the by-product formation of nuclear brominated BEBS, it should be controlled to 1000 ppm or less each, preferably 500 ppm or less each, by distillation and / or drying agents. Examples of desiccants include silica gel, zeolite, molecular sieves, calcium chloride, magnesium sulfate, calcium sulfate, sodium sulfate, calcium hydride, phosphorus pentoxide, and alumina. By treating 2-bromoethylbenzene and the reaction solvent with these desiccants, the moisture content in the reaction system is reduced.

[0034] The BEBS obtained by the above method is usually extracted from the reaction solution with water, and then the contaminating reaction solvent and water are removed by distillation and concentration to obtain a 65% to 75% by weight aqueous solution of BEBS, which is used in the production of alkali metal styrene sulfonates. The organic solvent and unreacted 2-bromoethylbenzene used in the sulfonation process of 2-bromoethylbenzene are usually recovered and recycled. In particular, moisture tends to remain in the recovered organic solvent, so moisture control using the method described above is extremely important.

[0035] There are no particular restrictions on the reaction solvent as long as it is inert to the sulfonating agent, but for example, halogenating solvents such as carbon tetrachloride, 1,2-dichloroethane, methylene chloride, 1,1,2-trichloroethane, chloroform, chlorobenzene, dichlorobenzene, bromobenzene, dibromobenzene, and bromohexane, nitrating solvents such as nitromethane and nitrobenzene, and aliphatic hydrocarbons such as hexane, cyclohexane, and methylcyclohexane can be used.

[0036] In addition to the above, it is important to control the concentration of the sulfonating agent supplied to the reactor and the molar ratio of the sulfonating agent to 2-bromoethylbenzene within a specific range. From the viewpoint of suppressing the by-production of nuclear brominated BEBS, it is preferable that the iron, hydrogen bromide, and water content in the reaction system be zero or as close to zero as possible. Furthermore, the lower the substrate concentration, especially the sulfonating agent concentration, the better. However, considering practical productivity, there is a limit to how low the substrate concentration can be. To produce high-purity BEBS without impairing productivity, it is preferable to react 2-bromoethylbenzene (or its organic solvent solution) and the sulfonating agent (or its organic solvent solution) by simultaneously and continuously supplying them to the reactor. Batch reaction using a tank reactor, or flow reaction using a tubular or tube reactor can be applied. For mass production, the flow reaction is more preferable from the viewpoint of production efficiency.

[0037] In the present invention, when using sulfuric acid anhydrous, which is most suitable as a sulfonating agent, it is preferable to maintain the concentration of sulfuric acid anhydrous in the reactor at 5.00% to 20.00% by weight, and to maintain the molar ratio of sulfuric acid anhydrous to 2-bromoethylbenzene in the reactor, i.e., the ratio of the number of moles of each supplied to the reactor, at 0.50 to 2.00, while reacting at 10°C to 60°C for 0.5 to 5.0 hours. Here, the concentration of sulfuric acid anhydrous is calculated as (weight of sulfuric acid anhydrous supplied to the reactor / total weight of the reaction solution in the reactor) × 100. To achieve both a high reaction conversion rate and selectivity, it is preferable to maintain the concentration of anhydrous sulfuric acid in the reactor [(weight of anhydrous sulfuric acid supplied to the reactor / total weight of reaction solution in the reactor) × 100] at 10.00% to 20.00% by weight, and to maintain the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene in the reactor (ratio of the number of moles of each supplied to the reactor) at 0.95 to 1.50, while reacting at 20°C to 50°C for 0.5 to 3.0 hours.

[0038] Another reaction method involves continuously supplying the aforementioned raw materials to the reactor simultaneously. This can be done by continuously supplying anhydrous sulfuric acid (or its organic solvent solution) to 2-bromoethylbenzene (or its organic solvent solution), maintaining a low concentration of anhydrous sulfuric acid in the reaction system. In this case, the concentration of anhydrous sulfuric acid in the reactor [(weight of anhydrous sulfuric acid supplied to the reactor / total weight of the reaction solution in the reactor) × 100] should be increased over 0.5 to 5 hours to a concentration not exceeding 20.00% by weight, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene in the reactor (ratio of the number of moles of each supplied to the reactor) should be increased to a molar ratio not exceeding 2.00 while reacting at 10°C to 60°C for 0.5 to 10.0 hours.

[0039] As the sulfonating agent, sulfuric acid anhydrous is preferred because it is highly reactive, can complete the reaction with an equivalent amount, and does not produce by-products such as hydrochloric acid. Furthermore, to prevent the formation of sulfonates during the sulfonation reaction, it is preferable to add 5% to 10% by weight of an organic carboxylic acid such as acetic acid or acetic anhydride relative to the sulfonating agent, and the reaction should be carried out with sufficient stirring to prevent the localization of the sulfonating agent. The appropriate amount of sulfonating agent relative to 2-bromoethylbenzene is not necessarily the same depending on the type of sulfonating agent, but when using anhydrous sulfuric acid, which is most suitable in the present invention, 0.50 equivalents to 2.00 equivalents is preferred, and 0.95 equivalents to 1.20 equivalents is more preferred in order to achieve both a high conversion rate and high selectivity (suppression of side reactions). Furthermore, to milden the reactivity of sulfuric anhydride, compounds that form complexes with sulfuric anhydride, such as tertiary amines like triethylamine and pyridine, aprotic polar solvents like N,N-dimethylformamide, dioxane, and dimethyl sulfoxide, and phosphate triesters like trimethyl phosphate and triethyl phosphate, may be added in amounts of 0.5 to 1.5 equivalents relative to sulfuric anhydride. Because anhydrous sulfuric acid is highly reactive, it can react sufficiently even at temperatures below 10°C. However, considering temperature control in actual manufacturing, temperatures above 10°C are preferable, and considering the selectivity of the reaction, temperatures below 60°C are preferable.

[0040] The mechanism that immediately comes to mind as the formation mechanism of nuclear brominated BEBS is the electrophilic substitution reaction of the benzene ring by Br2 (see, for example, Vollhardt & Schore, Modern Organic Chemistry, pp. 698-700, Kagaku Dojin Co., Ltd., published in 2000). That is, hydrogen bromide, which may be present in 2-bromoethylbenzene or recycled solvents, is oxidized to Br2, and trace amounts of iron that may be present in the reaction system act as a catalyst to form nuclear brominated BEBS.

[0041] However, after the inventors thoroughly examined the reaction conditions, they found that while nuclear brominated BEBS is indeed produced by the coexistence of hydrogen bromide and iron, the water content in the reaction system has a greater impact on the actual manufacturing process. In other words, it was found that when sulfonating 2-bromoethylbenzene using anhydrous sulfuric acid, even if hydrogen bromide and iron are removed from the starting materials, more nuclear brominated BEBS are produced in the presence of water. It is thought that the bromine source in this case is nothing other than the bromine bonded to the ethyl group of 2-bromoethylbenzene, but the reaction mechanism is not clear. Furthermore, while various isomers are expected to exist in nuclear brominated BEBS, sorting and identifying impurities observed in liquid chromatography analysis of BEBS revealed that 2-bromo-4-(2-bromoethyl)benzenesulfonic acid is one of the main isomers. When producing styrene sulfonic acids using BEBS, it is thought that the higher the amount of nuclear brominated BEBS in the BEBS, the greater the amount of bound bromine and unstable bound bromine in the styrene sulfonic acids.

[0042] <Styrene sulfonic acids> Next, the styrene sulfonic acids of the present invention will be described. Among the styrene sulfonic acids, the method for producing alkali metal styrene sulfonates with reduced bound bromine content can be basically the same as known methods, except that high-purity BEBS with reduced nuclear brominated BEBS content is used as a raw material. For example, as described above, sodium styrene sulfonate, lithium styrene sulfonate, or potassium styrene sulfonate can be produced by crystallizing BEBS in an aqueous solution while reacting it with an alkali such as sodium hydroxide, lithium hydroxide, or potassium hydroxide (for example, International Publication No. WO2014 / 061357, Japanese Patent Publication No. 2015-164911).

[0043] The method for producing styrene sulfonate esters with reduced bound bromine content among styrene sulfonic acids is basically the same as the method described above, except that high-purity BEBS with reduced nuclear brominated BEBS content is used as a raw material. That is, sodium styrene sulfonate is reacted with thionyl chloride to form styrene sulfonyl chloride, and then esterified with a base such as potassium hydroxide and an alcohol.

[0044] Among the styrenesulfonic acids, styrenesulfonylimide, for example, 4-styrenesulfonyl(trifluoromethylsulfonylimide) sodium salt with reduced bound bromine content, can be produced using basically the same methods as known, except that high-purity BEBS with reduced nuclear brominated BEBS content is used as a raw material (precursor). For example, a method of reacting sodium carbonate, trifluoromethanesulfonamide, and the above-mentioned styrenesulfonyl chloride in an organic solvent can be applied (for example, Japanese Patent Application Publication No. 2017-132728). Furthermore, 4-styrenesulfonyl(fluorosulfonylimide) potassium salt can be produced, for example, by mixing styrenesulfonyl chloride, dipotassium hydrogen phosphate, 4-tert-butylcatechol, and dimethylaminopyridine in acetonitrile at 0°C under a nitrogen atmosphere, adding fluorosulfonamide, and reacting at room temperature for 72 hours. Furthermore, by reacting the potassium salt with lithium perchlorate, it can be converted to 4-styrenesulfonyl(fluorosulfonylimide) lithium salt (e.g., Qiang Ma et al.; RSC Advances, 2016, No. 6, pp. 32454-32461). In addition, among the bis(styrylsulfonylimide) salts, for example, the lithium salt can be produced by reacting styrenesulfonyl chloride and styrenesulfonilamide in an anhydrous organic solvent in the presence of lithium hydride (e.g., Japanese Patent Publication No. 2016-128562).

[0045] Regarding the production method of styrenesulfonic acid amine salts with reduced bound bromine content among styrenesulfonic acids, the method is basically the same as known methods, except that alkali metal styrenesulfonic acid salts with reduced bound bromine content are used as raw materials. For example, a method can be applied in which an aqueous solution of N,N'-dimethylcyclohexylamine hydrochloride is added to an aqueous solution of sodium styrenesulfonate for cation exchange, and then the N,N'-dimethylcyclohexylamine styrenesulfonic acid salt is extracted with an organic solvent such as chloroform and dried (for example, International Publication No. WO2019 / 031454). Regarding the production method of ammonium styrenesulfonate, which has a reduced amount of bound bromine among the styrenesulfonic acids, the method is basically the same as known methods, except that an alkali metal salt of styrenesulfonate with reduced bound bromine is used as a raw material. For example, when sodium styrenesulfonate and ammonium sulfate are mixed in methanol at 65°C, methanol-soluble ammonium styrenesulfonate is produced. After filtering off the methanol-insoluble sodium styrenesulfonate, ammonium styrenesulfonate can be produced by distilling off the methanol (for example, Japanese Patent Publication No. 50-149642). Regarding the production of phosphonium styrenesulfonate, which has a reduced amount of bound bromine among the styrenesulfonic acids, the only difference is the use of an alkali metal salt of styrenesulfonate with reduced bound bromine as a raw material; otherwise, known methods can be applied. For example, tetrabutylphosphonium styrenesulfonate can be produced by adding tetrabutylphosphonium bromide and sodium styrenesulfonate to water, stirring thoroughly to dissolve, then extracting with an organic solvent and washing with pure water (for example, International Publication No. WO2015 / 147749).

[0046] <Polystyrene sulfonic acids> The present invention's method for producing polystyrene sulfonic acids can use styrene sulfonic acids in which the amount of bound bromine is reduced as the monomer. Known methods can also be applied to the specific production process. That is, general radical polymerization methods and emulsion polymerization methods using radical polymerization initiators, photosensitizers, ultraviolet light, and radiation (for example, Kamachi et al.; Revised Edition Radical Polymerization Handbook, 2010, NTS Publishing Co., Ltd.; Lovel Peter A. et al.; Emulsion Polymerization and Emulsion Polymers, 1997, John Wiley & Son) In addition to the methods described in Ltd., controlled radical polymerization methods such as atom transfer polymerization (ATRP), reversible addition-cleavage transfer (RAFT) polymerization, iodine transfer polymerization (ITP), stable nitroxyl-mediated polymerization (NMP), and organotellurium-mediated polymerization (TERP) can be applied (e.g., Yamako et al., Journal of the Rubber Association of Japan, Vol. 82, No. 8, pp. 363-369, 2009; Uegaki et al., Network Polymer, Vol. 30, No. 5, pp. 234-249, 2009). Furthermore, when using styrene sulfonic acid esters among the styrene sulfonic acids, anionic polymerization using organometallic catalysts (e.g., Tadaki et al.; Network Polymer, Vol. 38, No. 1, pp. 14-20, 2017) can also be applied.

[0047] Of the polymerization methods described above, the radical polymerization method, which is highly versatile, will be explained in detail. For example, a solvent, styrene sulfonic acids, and, if necessary, monomers other than styrene sulfonic acids that can be radically copolymerized with styrene sulfonic acids are added to a reaction vessel. Furthermore, polymerization control agents such as the stable nitroxyl compounds or molecular weight modifiers such as mercaptan compounds and radical polymerization initiators such as azo compounds are added. After deoxygenating the reaction system, polymerization is carried out while heating to a predetermined temperature to produce a solvent-soluble polymer having a desired molecular weight. The molecular weight of the polymer is 500 to 5,000,000 daltons as a number average molecular weight, but considering the polymerizability of styrene sulfonic acids, 500 to 1,000,000 daltons is preferred, and 1,000 to 600,000 daltons is more preferred.

[0048] Furthermore, among the styrene sulfonic acids, styrene sulfonic acid esters, styrene sulfonic acid amines, and lithium styrene sulfonate have high solubility in various solvents, allowing for the preparation of high-concentration solutions. For this reason, for example, by adding photopolymerization initiators, photosensitizers, crosslinkable monomers such as divinylbenzene, and optionally molecular weight modifiers and thickeners to these styrene sulfonic acids to a monomer solution, injecting it between transparent glass plates or films, or impregnating a nonwoven fabric with it, and polymerizing it by irradiation with ultraviolet light, polystyrene sulfonic acid coatings and crosslinked films can be easily manufactured. However, in the case of crosslinked films, the polymer is insoluble in solvents, making it difficult to measure the number-average molecular weight.

[0049] The solvent used in the above reaction is not particularly limited as long as it can dissolve the monomer mixture. Examples include anisole, dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, dihydrolevoglucocenone, acetonitrile, dioxane, tetrahydrofuran, toluene, benzene, chlorobenzene, xylene, diethyl carbonate, dimethyl carbonate, ethylene carbonate, acetone, methanol, ethanol, propanol, butanol, methoxyethanol, methoxypropanol, propylene glycol monomethyl ether acetate, water, aqueous solutions of alkali metal halides, and mixed solvents thereof. The amount of polymerization solvent used is typically 0 to 2,000 parts by weight per 100 parts by weight of the total amount of monomer. When polymerizing powdered monomers such as styrene sulfonates, typically 50 to 1,000 parts by weight of polymerization solvent is used.

[0050] On the other hand, among the styrenesulfonic acids, styrenesulfonic acid esters and certain amine salts are liquid or low-melting-point monomers, so a reaction solvent is not necessarily required. Furthermore, among the styrenesulfonic acids, styrenesulfonic acid esters are oil-soluble monomers and are miscible with common monomers such as styrene and (meth)acrylic acid esters, so they can be applied to emulsion polymerization, suspension polymerization, or dispersion polymerization. For example, polystyrenesulfonic acid ester fine particles or fine particles modified with styrenesulfonic acid ester structural units can be produced by emulsifying or finely dispersing styrenesulfonic acid ester and monomers copolymerizable therewith in water using a nonionic emulsifier, anionic emulsifier, cationic emulsifier, and / or water-soluble polymer, and then polymerizing while adding a radical polymerization initiator.

[0051] The molecular weight modifier is not particularly limited, but examples include disulfides such as diisopropyl xanthogen disulfide, diethyl xanthogen disulfide, diethyl thiuram disulfide, 2,2'-dithiodipropionic acid, 3,3'-dithiodipropionic acid, 4,4'-dithiodibutanoic acid, and 2,2'-dithiobisbenzoic acid, as well as n-dodecyl mercaptan, octyl mercaptan, t-butyl mercaptan, and thio Glycolic acid, thiomalic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiosalicylic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, thiomalonic acid, dithiosuccinic acid, thiomaleic acid, thiomaleic acid anhydride, dithiomaleic acid, thioglutaric acid, cysteine, homocysteine, 5-mercaptotetrazoleacetic acid, 3-mercapto-1-propanesulfonic acid, 3-mercaptopropane Examples include -1,2-diols, mercaptoethanol, 1,2-dimethylmercaptoethane, 2-mercaptoethylamine hydrochloride, 6-mercapto-1-hexanol, 2-mercapto-1-imidazole, 3-mercapto-1,2,4-triazole, cysteine, N-acylcysteine, glutathione, mercaptans such as N-butylaminoethanethiol and N,N-diethylaminoethanethiol, iodized hydrocarbons such as iodoform, benzyl dithiobenzoate, 2-cyanoprop-2-yldithiobenzoate, diphenylethylene, p-chlorodiphenylethylene, p-cyanodiphenylethylene, α-methylstyrene dimer, organotellurium compounds, sulfur, sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, sodium pyrosulfite, potassium pyrosulfite, sodium hypophosphate, etc. The amount of molecular weight modifier used is typically 0.0 to 15.0 parts by weight per 100 parts by weight of total monomer. Molecular weight modifiers are effective additives for reducing the molecular weight and branching of the polymer being manufactured, or for improving the homogeneity of the membrane when producing polymer electrolytes using crosslinkable monomers. However, they can also reduce the polymerization rate and copolymerizability, or cause odors. Therefore, depending on the purpose, molecular weight modifiers are not always necessary, and molecular weight can be adjusted by increasing the amount of polymerization initiator, adjusting the polymerization temperature, or by adjusting the addition conditions of monomers and polymerization initiators.

[0052] Examples of the radical polymerization initiators mentioned above include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, dilauryl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)-cyclohexane, cyclohexanone peroxide, t-butyl peroxybenzoate, t-butyl peroxyisobutyrate, and t-butyl peroxyisobutyrate. Peroxides such as t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisopropyl carbonate, cumyl peroxyoctoate, potassium persulfate, ammonium persulfate, hydrogen peroxide, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-A Zobis(cyclohexane-1-carbonitride), 1-[(1-cyano-1-methylethyl)azo]formamide, dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis{2-methyl-N-[1,1'-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-(2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-a Azo compounds such as zobis{2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl)propane]} dihydrochloride, 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate, 4,4'-Bis(diethylamino)benzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, ethyl-4-(dimethylamino)-benzoate, [4-(methylphenylthio)phenyl]-phenylmethane, ethylhexyl-4-dimethylaminobenzoate, benzophenone, methyl-o-benzoylbenzoate, o-benzoylbenzoic acid, 4-methylbenzophenone, 1-hydroxycyclohexylphenyl ketone, methylbenzoyl formate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,2-dimethoxy-2-phenyl Examples of photopolymerization initiators include acetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropane, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane. Additionally, reducing agents such as ascorbic acid, erythorbic acid, aniline, tertiary amines, rongalit, hydrosulfite, sodium sulfite, and sodium thiosulfate may be used in combination as needed. The amount of radical polymerization initiator used is typically 0.1 to 15 parts by weight per 100 parts by weight of the total amount of monomer.

[0053] While the polymerization conditions are not particularly limited, heating at 20°C to 120°C for 4 to 50 hours under an inert gas atmosphere is sufficient, and these conditions can be appropriately adjusted depending on the polymerization solvent, monomer composition, and polymerization initiator type. For photopolymerization, a wavelength of 250 nm to 450 nm and an illuminance of 20 mW / cm² are used. 2 ~1,000 mW / cm 2 Polymerization can be carried out using ultraviolet light at 10°C to 60°C for 0.1 to 5 hours.

[0054] The monomers other than styrene sulfonic acids used in the production of polystyrene sulfonic acids of the present invention are not particularly limited as long as they can copolymerize with styrene sulfonic acids. For example, styrenes such as styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, fluorostyrene, trifluorostyrene, nitrostyrene, cyanostyrene, α-methylstyrene, p-chloromethylstyrene, p-acetoxystyrene, p-styrenesulfonyl chloride, styrenesulfonyl bromide, styrenesulfonyl fluoride, p-butoxystyrene, 4-vinylbenzoic acid, 3-isopropenyl-α,α'-dimethylbenzyl isocyanate, vinylbenzyltrimethylammonium chloride, vinyl ethers such as butyl vinyl ether, propyl vinyl ether, ethyl vinyl ether, 2-phenyl vinyl alkyl ether, nitrophenyl vinyl ether, cyanophenyl vinyl ether, chlorophenyl vinyl ether, chloroethyl vinyl ether, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, Pentyl acrylate, hexyl acrylate, decyl acrylate, lauryl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, bornyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, 2-hydroxyethyl acrylate, tetrahydrofurfuryl acrylate, methoxyethylene glycol acrylate, ethyl carbitol acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-(trimethoxysilyl)propyl acrylate, polyethylene glycol acrylate, glycidyl acrylate, 2-(acryloyloxy)ethyl phosphate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,4,4,Acrylic acid esters such as 4-hexafluorobutyl, methyl methacrylate, t-butyl methacrylate, sec-butyl methacrylate, i-butyl methacrylate, i-propyl methacrylate, decyl methacrylate, lauryl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, bornyl methacrylate, benzyl methacrylate, phenyl methacrylate, glycidyl methacrylate, polyethylene glycol methacrylate Crylate, 2-hydroxyethyl methacrylate, tetrahydrofurfuryl methacrylate, methoxyethylene glycol methacrylate, ethyl carbitol methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-(methacryloyloxy)ethyl phosphate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, 3-(dimethylamino)propyl methacrylate, 2-(isocyanthyl) methacrylate Methacrylic acid esters such as ethyl methacrylate, 2,4,6-tribromophenyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2,2,3,4,4,4-hexafluorobutyl methacrylate, diacetone methacrylate, methacryloxypropyltrimethoxysilane, and methacryloxypropyldimethoxysilane, isoprene sulfonic acid, 1,3 -Butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 2-cyano-1,3-butadiene, 1-chloro-1,3-butadiene, 2-(N-piperidylmethyl)-1,3-butadiene, 2-triethoxymethyl-1,3-butadiene, 2-(N,N-dimethylamino)-1,3-butadiene, N-(2-methylene-3-butenoyl)morpholine, 2-methylene-3-butenylphosphonate diethyl, etc.3-Butadienes, N-phenylmaleimide, N-(chlorophenyl)maleimide, N-(methylphenyl)maleimide, N-(isopropylphenyl)maleimide, N-(sulfophenyl)maleimide, N-methylphenylmaleimide, N-bromophenylmaleimide, N-naphthylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-(nitrophenyl)maleimide, N-benzylmaleimide, N -(4-acetoxy-1-naphthyl)maleimide, N-(4-oxy-1-naphthyl)maleimide, N-(3-fluoranthyl)maleimide, N-(5-fluoresceinyl)maleimide, N-(1-pyrenyl)maleimide, N-(2,3-xylyl)maleimide, N-(2,4-xylyl)maleimide, N-(2,6-xylyl)maleimide, N-(aminophenyl)maleimide, N-(tribromophenyl)maleimide, N-[4-(2-benzimidazolyl)phenyl]maleimide Maleimides such as imides, N-(3,5-dinitrophenyl)maleimide, N-(9-acridinyl)maleimide, maleimide, N-(sulfophenyl)maleimide, N-cyclohexylmaleimide, N-methylmaleimide, N-ethylmaleimide, and N-methoxyphenylmaleimide; fumarate diesters such as dibutyl fumarate, dipropyl fumarate, diethyl fumarate, and dicyclohexyl fumarate; and fumarates such as butyl fumarate, propyl fumarate, and ethyl fumarate. Monoesters, maleic acid diesters such as dibutyl maleate, dipropyl maleate, and diethyl maleate, maleic acid monoesters such as butyl maleate, propyl maleate, ethyl maleate, and dicyclohexyl maleate, acid anhydrides such as maleic anhydride and citraconic anhydride, acrylamide, N-methylacrylamide, N-ethylacrylamide, 2-hydroxyethylacrylamide, N,N-diethylacrylamide, acryloylmorpholine, N,N-dimethylaminopropyl acrylamide, isopropyl acrylamide, N-methylol acrylamide, sulfophenyl acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-1-methylsulfonic acid, diacetone acrylamide, acrylamide alkyltrialkylammonium chloride and other acrylamides, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, 2-hydroxyethylmethacrylamide, N,N-diethylmethacrylamide, N,N-dimethylmethacrylamide, N-methylolmethacrylamide, methacryloylmorpholine, N,N-dimethylaminopropyl methacrylamide, isopropyl methacrylamide, 2-methacrylamide-2-methylpropanesulfonic acid, methacrylamide alkyltrialkylammonium chloride and other methacrylamides, vinylpyridine, vinyl chloride, vinylidene chloride, vinylpyrrolidone, sulfophenylitaconimide, acrylonitrile, methacrylonitrile, fumaronitrile, α-cyanoethyl acrylate, citraconic acid, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl versamicate, crotonic acid, itaconic acid, fumaric acid, maleic acid, Examples include mono-2-(methacryloyloxy)ethyl phthalate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(acryloyloxy)ethyl succinate, acrolein, vinyl methyl ketone, N-vinylacetamide, N-vinylformamide, vinyl ethyl ketone, vinyl sulfonic acid, allyl sulfonic acid, dehydroalanine, sulfur dioxide, isobutene, N-vinylcarbazole, vinylidene dicyanide, paraquinodimethane, chlorotrifluoroethylene, tetrafluoroethylene, norbornene, N-vinylcarbazole, acrylic acid, methacrylic acid, etc. Among these, (meth)acrylic acid, (meth)acrylic acid esters, N-substituted maleimide, (meth)acrylamide, styrenes, and vinylpyridine are preferred, considering copolymerizability with styrene sulfonic acids and availability. Furthermore, there are no particular restrictions on the monomers used when manufacturing crosslinked films or crosslinked particles, but they include substituted styrenes such as divinylbenzene, bis-(4-styrenesulfonyl)imide, and divinylbenzenesulfonic acid, (meth)acrylic acid esters such as polyethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, and triethylene glycol diacrylate, N,N'-methylenebisacrylamide, N-[tris(3-acrylamidopropoxymethyl)-methyl]acrylamide, N,N-bis(2-acrylamidoethyl)acrylamide, and N,N'-[oxybis(1,2-ethanediyloxy-3,Examples include (meth)acrylamides such as 1-propanediyl)bisacrylamide, N,N'-1,2-ethanediylbis{N-[2-(acryloylamino)ethyl]acrylamide}, and N,N'-methylenebismethacrylamide, as well as substituted maleimides such as 1,2-bismaleimideethane, 4,4'-bismaleimidediphenylmethane, 1,6-bismaleimidehexane, 1,4-bismaleimidebutane, N,N'-1,4-phenylenedimaleimide, and N,N'-1,3-phenylenedimaleimide. The proportion of monomers copolymerizable with the styrene sulfonic acids mentioned above is between 0.0 mol% and 99.0 mol% of the total monomers. For example, when polystyrene sulfonic acids are used as dopants in conductive polymer dispersions, a lower amount of the monomer is better in terms of dispersion stability and conductivity, while a higher amount is better in terms of water resistance and durability of the conductive film; therefore, the proportion is between 0.0 mol% and 50.0 mol%. Furthermore, when used in polymer electrolyte membranes, the performance, such as ion exchange capacity, is determined by the concentration of sulfonic acid groups, so the amount of monomer used is limited, for example, to 0.0 mol% to 30 mol%. On the other hand, for example, when polystyrene sulfonic acid compounds are used as spacer microparticles in liquid crystal displays, the monomer is the main component, and the styrene sulfonic acid compounds are stabilizers for producing the microparticles, i.e., minor components (secondary components), so their concentration is between 50.0 mol% and 99.0 mol%. The copolymerization method is not particularly limited; in addition to random copolymers, alternating copolymers, and graft copolymers, block copolymers can be produced by applying the controlled polymerization method described above.

[0055] The BEBS produced by this invention, which has reduced nuclear brominated BEBS, is extremely useful as a precursor for producing styrene sulfonic acids and their polymers with reduced bound bromine. The polymer of these styrene sulfonic acids can be used as is, but the bound bromine can be further reduced by subjecting it to the following chemical treatment. Specifically, this method involves adding an alkali, or an alkali and a reducing agent, to an aqueous solution of polystyrene sulfonic acid obtained above, and heating it at 80°C to 150°C for 5 to 30 hours while maintaining the solution pH at 13 or higher to release the bound bromine present in the polymer, and then purifying the polymer. To reduce the bound bromine without degrading the polymer, such as causing discoloration, it is more preferable to heat-treat it at 90°C to 110°C for 10 to 25 hours.

[0056] While the chemical treatment can be carried out in air, an inert gas atmosphere such as nitrogen or argon is preferred from the viewpoint of suppressing the deactivation of reducing agents and the deterioration of polystyrene sulfonic acids. Examples of alkalis include sodium hydroxide, potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide, while examples of reducing agents include sodium sulfite, rongalit, hydrosulfite, sodium thiosulfate, and sodium hypophosphite. The amount of reducing agent to be added is 0.5 to 1.5 times the molar amount of the alkali mentioned above. Other chemical treatment methods include combinations of reducing agents such as sodium formate or hydrazine with palladium-carbon catalysts. For example, 1.0% to 5.0% by weight of a reducing agent and 1.0% to 20% by weight of palladium-carbon (for a Pd content of 5% by weight) relative to the purity of polystyrene sulfonic acid are added, and the mixture is treated at 80°C to 110°C for 5 to 30 hours.

[0057] As for the purification method after processing, methods using cation exchange resins, anion exchange resins, cation exchange filters, anion exchange filters, chelate fibers, ultrafiltration membranes, activated carbon, and reprecipitation purification can be applied. However, considering applicability to high-viscosity polymer aqueous solutions, the use of cation exchange resins, anion exchange resins, and ultrafiltration membranes is preferred.

[0058] The aqueous polystyrene sulfonic acid solution of the present invention can be used as is for various purposes, but in order to suppress the cleavage of polymer chains during long-term storage, it is preferable to add a phenolic antioxidant in an amount of 20 ppm to 2,000 ppm relative to the pure polystyrene sulfonic acid as a stabilizer. The phenolic antioxidant is not particularly limited, but it is preferable to use one that dissolves in the aqueous polystyrene sulfonic acid solution, and examples include 2-methoxyphenol, 3-methoxyphenol, 4-methoxyphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-tert-butylcatechol, hydroquinone, methoxyhydroquinone, and ethoxyhydroquinone.

[0059] Furthermore, when the polystyrene sulfonic acid of the present invention is neutralized with ammonia, amine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc., and used as an ammonium salt, that is, when the pH of the aqueous solution is neutral or higher, the addition of the above-mentioned antioxidant is not necessarily required.

[0060] The styrene sulfonic acids and polymers of the present invention, with reduced bound bromine content, are extremely useful, particularly in electronic materials applications, such as battery components, organic EL components, photoresist components, dispersants and dopants for conductive polymers and carbon nanotubes, dispersants for chemical mechanical polishing slurries, and semiconductor cleaning agents, because they have reduced levels of unstable bound bromine that would otherwise be released under mild conditions. [Examples]

[0061] The present invention will be described in more detail by the following examples, but the present invention is not limited in any way by these examples.

[0062] In the following examples, the analysis and evaluation of the compounds were carried out under the following conditions. <Analysis of iron content in BEB and organic solvents by inductively coupled plasma emission spectrometry (ICP-AES)> Equipment: PerkinElmer NexIon™ 300S Sample preparation: Approximately 0.1 g of the sample was accurately weighed into a 25 ml polyvolume flask, 1 ml of 68% high-purity nitric acid was added, and the solution was made up with ultrapure water to prepare the sample for measurement.

[0063] <Analysis of moisture in BEB and organic solvents using the Karl Fischer method> Device: MKC-610 manufactured by Kyoto Electronics Manufacturing Co., Ltd. Anode liquid: ChemAqua Anode Liquid AGE (manufactured by Kyoto Electronics Manufacturing Co., Ltd.) Cathode solution: ChemAqua Cathode Solution CGE (manufactured by Kyoto Electronics Manufacturing Co., Ltd.)

[0064] <Analysis of hydrogen bromide content in BEB and organic solvents by ion chromatography (IC)> Equipment: IC-2001 manufactured by Tosoh Corporation Column: TSKgel(registered trademark) SuperIC-AP Detector: Electrical conductivity, Flow rate: 0.8 ml / min, Column temperature: 40°C Calibration curve: Absolute calibration curve method using anion standard solutions Sample preparation: The sample was extracted by shaking with ultrapure water, then centrifuged, and the aqueous layer was passed through a pretreatment cartridge (TOYOPAK® ODS M, manufactured by Tosoh Corporation) to obtain the sample for measurement. The dilution ratio was adjusted according to the HBr concentration, for example, sample / ultrapure water = 2 ml / 200 ml to 2 ml / 4 ml.

[0065] <Measurement of BEB conversion rate by high-performance liquid chromatography (HPLC)> The conversion rate (area %) of BEB in the sulfonation reaction of BEB was measured under the following conditions. Equipment: Manufactured by Tosoh Corporation Column: TSKgel® ODS-80™ (4.6mm I.D. × 25cm) Eluent: A) 20 mM NaH2PO4 (pH=2.4) aqueous solution / acetonitrile = 90 / 10 volume ratio B) 20 mM NaH2PO4 (pH=2.4) aqueous solution / acetonitrile = 60 / 40 volume ratio Gradient: A → B (Linear gradient for 60 minutes, then continue with solution B for 30 minutes) Detector: UV230m, Column temperature: 25℃, Flow rate: 0.8 ml / min, Injection volume: 20 μl

[0066] <Analysis of BEBS aqueous solution concentration by high-performance liquid chromatography (HPLC)> The concentration of the BEBS aqueous solution was analyzed under the following conditions. Column: TSKgel(registered trademark) ODS-80TsQA (4.6mm I.D. × 25cm) Eluent: Water / Acetonitrile = 80 / 20 volume ratio + 0.1 wt% trifluoroacetic acid Detector: Ultraviolet UV230m Column temperature: 40°C, Flow rate: 0.8 ml / min Calibration curve: An absolute calibration curve was used, using crystals recovered from the BEBS aqueous solution prepared in Example 2 as standard material.

[0067] <Analysis of impurities in BEBS by high-performance liquid chromatography (HPLC)> The nuclear brominated compounds (area %) in BEBS aqueous solution were analyzed under the following conditions. Equipment: Manufactured by Tosoh Corporation Column: TSKgel® ODS-80™ (4.6mm I.D. × 25cm) Eluent: A) 20 mM NaH2PO4 (pH=2.4) aqueous solution / acetonitrile = 90 / 10 volume ratio B) 20 mM NaH2PO4 (pH=2.4) aqueous solution / acetonitrile = 60 / 40 volume ratio Gradient: A→B (Linear gradient 60 minutes) Detector: UV230m, Column temperature: 25℃, Flow rate: 0.8 ml / min, Injection volume: 20 μl Sample preparation: BEBS aqueous solution (concentration 69.0-73.0 wt%) 5 mg / eluent 1 ml

[0068] Furthermore, the UK components in BEBS produced by the conventional method (Comparative Example 4 shown below), i.e., peaks (A), (C), (D), and (E) in Figure 1, were identified in advance by the following method. Each component was column-associated, and the sulfonic acid group was methyl-esterified with diazomethane. Then, gas chromatography-mass spectrometry (Hitachi M-80B), Fourier transform infrared spectrometry (PerkinElmer System2000), organic elemental analysis (Yanaco CHN Coder MT-3), and nuclear magnetic resonance spectrometry (Varian VXR-300) were performed to attempt identification. In addition, (E) was identified directly by TOF-MS without esterification.

[0069] <Identification of brominated BEBS by time-of-flight mass spectrometry (TOF-MS)> The peak (E) detected by the above HPLC was measured using TOF-MS. Device: Bruker Daltonics microTOF Ion source: ESI Measurement mode: Negative mode Sample preparation: The sample was dissolved in methanol, and then diluted in a methanol / water ratio of 1 / 1 volume.

[0070] <Proton nuclear magnetic resonance () 1 Analysis of ClSS toluene solution concentration by 1H-NMR > Under the following conditions, the styrene sulfonyl chloride (ClSS) solution 1 1H-NMR was measured. Equipment: Bruker AV-400M Solvent: Deuterated dimethyl sulfoxide The ClSS concentration was calculated using the following formula based on the integral ratio of the two meta protons of toluene to the one proton of the CH2= group within the ClSS vinyl group CH2=CH-. ClSS concentration = 100 × 202.65 / (202.65 + 92 × toluene integral ratio / 2)

[0071] <Analysis of ETSS by gas chromatography (GC)> The GC purity (area %) of ethyl styrene sulfonate (ETSS) was analyzed under the following conditions. Equipment: Shimadzu Corporation GC-2014 Column: NEUTRABOND-1 (φ0.32mm × 30m, 0.4μm) Injection: 220℃, injection volume 0.2μl Carrier gas: Helium, Linear velocity: 30 cm / min, Split ratio: 100 Detector: FID, 250℃ Heating conditions: Hold at 80°C for 10 minutes, then increase temperature at 5°C / minute to 250°C, and hold for 6 minutes. Sample: Neat

[0072] <Analysis of NaSS by high-performance liquid chromatography (HPLC)> Various organic impurities and isomers that may be present in sodium 4-styrenesulfonate were analyzed under the same conditions as described in the patent document (International Publication No. WO2014 / 061357). Equipment: Manufactured by Tosoh Corporation Column: TSKgel® ODS-80™ (4.6mm I.D. × 25cm) Eluent: A) 5 vol% acetonitrile aqueous solution (containing 0.1% trifluoroacetic acid) B) 20 vol% acetonitrile aqueous solution (containing 0.1% trifluoroacetic acid) Gradient: Solution A 100% (0-55 minutes) → Solution B 100% (55-95 minutes) Detector: UV230m, Column temperature: 25℃, Flow rate: 0.8 ml / min, Injection volume: 20 μl Sample preparation: Dissolve the sample in eluent A to prepare a solution with a concentration of 0.5 mg / 1 ml.

[0073] <Measurement of the purity of sodium styrene sulfonate> The active double bond was quantified by redox titration, and the sodium styrenesulfonate content in the sample (i.e., including ortho and meta isomers in addition to the para isomer) was determined. (1) Reagents 1) Bromine solution: 22.00 g of potassium bromide and 3.00 g of potassium bromate were dissolved in pure water to make a total volume of 1000 ml. 2) Sulfuric acid 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 solution: 6.00 g of starch was dissolved in pure water to make a total volume of 1000 ml. (2) Operation 1) Weigh 20g of the sample into a weighing bottle to the nearest 0.1mg. 2) Wash the liquid with distilled water and transfer it to a 500 ml volumetric flask, making the total volume approximately 400 ml. 3) Insert the magnetic rotor and stir to dissolve the sample. 4) Remove the rotor, fill it with distilled water, align it to the mark, shake it to prepare the test solution. 5) Add 25 ml of bromine solution to a 500 ml stoppered Erlenmeyer flask containing 200 ml of pure water. 6) After adding 5 ml of the test solution, add 10 ml of sulfuric acid solution, seal the container tightly, and let it stand for 20 minutes. 7) Quickly add 10 ml of potassium iodide solution and let stand for 10 minutes. 8) Titrate with sodium thiosulfate aqueous solution until the yellow color of the solution fades, then add 1 ml of starch solution as an indicator and titrate until the blue color of the resulting iodine-starch solution 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 solution and 10 ml of sulfuric acid solution, and perform the procedure in 8). (3) Calculation The sodium styrene sulfonate content is calculated using the following formula. A=100×[0.01031×(ab)×f] / (S×5 / 500) A: Sodium styrene sulfonate content (%) a: Sodium thiosulfate solution required for blank test (ml) b: Sodium thiosulfate solution required for this test (ml) f: Potency of sodium thiosulfate aqueous solution S: Sample quantity (g)

[0074] <Analysis of halogens in styrene sulfonic acids by combustion decomposition ion chromatography> The bromine and chlorine content in styrene sulfonic acids and polystyrene sulfonic acid was quantified under the following conditions. Combustion equipment: AQF-2100H manufactured by Mitsubishi Chemical Analytech Co., Ltd. Combustion temperature: inlet=900℃, outlet=1000℃ IC device: IC-2010 manufactured by Tosoh Corporation Column: TSK-guard column Super IC-AHS + TSK-gel Super IC-Anion HS Eluent: Carbonate buffer Absorbent solution: 900 ppm hydrogen peroxide solution Detector: Electrical conductivity Flow rate: 1.5ml / min, temperature: 40℃ Measurement mode: Suppressor type Calibration curve: Absolute calibration curve method using anion standard solutions

[0075] <Analysis of halogen ions in polystyrene sulfonic acid aqueous solution by ion chromatography> Halogen ions in an aqueous solution of polystyrene sulfonic acid were quantified under the following conditions. Equipment: IC-2001 manufactured by Tosoh Corporation Column: TSKgel(registered trademark) Super IC-AP Detector: Electrical conductivity Sample preparation: 20 g of the sample was diluted with ultrapure water to a concentration of 20 mg / ml. Polymer components were then removed using an ultrafiltration cartridge (molecular weight cutoff of 3,000 or 10,000) to prepare the sample for analysis.

[0076] <Quantitative determination of water content in 4-styrene sulfonate> Approximately 2 g of the sample was weighed to the nearest 0.1 mg in a weighing bottle (55 mm in diameter x 30 mm in height) and dried in a drying oven (105 ± 5 °C) for 90 minutes. Immediately afterward, it was transferred to a desiccator and cooled to room temperature. Its mass was then measured to the nearest 0.1 mg, and the moisture content was calculated using the following formula. Moisture (wt%)=100×(ab) / S a: Weight of sample and weighing bottle before drying (g), b: Weight of sample and weighing bottle after drying (g), S: Sample volume (g)

[0077] <Quantitative determination of bromine ions in 4-styrene sulfonic acids> Equipment: IC-2010, manufactured by Tosoh Corporation Column: TSKgel® Guard Column Super IC-AHS (4.6mm I.D. × 1cm) + TSKgel SuperIC-Anion HS (4.6mm I.D. × 10cm) Column temperature: 40°C, injection volume: 30 μl, flow rate: 1.5 ml / min Eluent: Carbonate buffer (7.5 mM NaHCO3 + 0.8 mM Na2CO3) Sample preparation for styrene sulfonate esters: 5 ml of ultrapure water and 5 g of the sample were placed in a screw-cap test tube, and after shaking extraction for 30 minutes, the mixture was centrifuged (2800 rpm, 30 minutes). The aqueous layer was passed through a pretreatment cartridge (TOYOPAK ODSM) to obtain the sample for measurement. Sample preparation for styrene sulfonates: The solid sample was dissolved in ultrapure water, diluted 10-fold, and passed through a pretreatment cartridge (TOYOPAK® ODSM) to prepare the sample for measurement. Calibration curve: Absolute calibration curve method using standard solutions

[0078] <Analysis of polymerization conversion rate and molecular weight of the resulting polymer of styrene sulfonate ester by gel permeation chromatography (GPC)> The area-based conversion rate and molecular weight were measured under the following conditions. Model: HLC-8320GPC manufactured by Tosoh Corporation Columns: TSK Guard Columns Super AW-H + TSK Super AW-6000 + TSK Super AW-4000 + TSK Super AW-2500 Eluent: N,N-dimethylformamide (10 mM lithium bromide) Column temperature: 40°C, Flow rate: 0.5 ml / min Detector: RI detector, injection volume: 10 μl Calibration curve: Created from the weight-average molecular weight and elution time of Tosoh's standard polystyrene kits PSt Quick C, D, and E. Conversion rate: The polymerization conversion rate was calculated from the peak area derived from the monomer (a) and the peak area derived from the polymer (b) using the following formula. Conversion rate (area %) = 100 × [1 - {a / (a+b)}]

[0079] <Analysis of polymerization conversion rate and molecular weight of the resulting polymer of styrene sulfonate by gel permeation chromatography (GPC)> The area-based conversion rate and molecular weight were measured under the following conditions. Model: HLC-8320GPC manufactured by Tosoh Corporation Columns: TSK Guard Column AW-H + TSK AW6000 + TSK AW3000 + TSK AW2500 Eluent: 0.05 M sodium sulfate aqueous solution / acetonitrile = 65 / 35 volume ratio Flow rate: 0.6 ml / min, injection volume: 10 μl, column temperature: 40°C Detector: UV detector (wavelength 230nm) Calibration curve: Created using standard sodium polystyrene sulfonate (manufactured by Sowa Kagaku Co., Ltd.) based on the peak top molecular weight and elution time at peak tops (3K, 15K, 41K, 300K, 1000K, 2350K, 5000K). Conversion rate: The polymerization conversion rate was calculated from the peak area derived from the monomer (a) and the peak area derived from the polymer (b) using the following formula. Conversion rate (area %) = 100 × [1 - {a / (a+b)}]

[0080] <Medications used> 2-Bromoethylbenzene: Manufactured by Tosoh Finechem Co., Ltd., 99.1% purity. 1,2-Dichloroethane: Manufactured by Tosoh Corporation, 99.9% purity. Anhydrous sulfuric acid: Manufactured by Nisso Metal Chemical Co., Ltd., Nisso Sulfan (registered trademark), purity 99.4% Acetic acid: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >99.5% Anhydrous barium hydroxide: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Orthoacetate triethyl: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >96% t-Butylcatechol: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 98% purity. t-Butoxypotassium: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >97% N,N-dimethylformamide: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >99.5% Irganox 1010: Manufactured by BASF Japan Ltd. Thionyl chloride: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >98% Neopentyl alcohol: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >98% Trifluoromethanesulfonamide: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >98% Pyridine: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >99% 4-Dimethylaminopyridine: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >98% Sodium carbonate: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >99% Ethyl acetate: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >98% Toluene: Manufactured by Tokyo Chemical Industry Co., Ltd. Purity >99.5% Sodium formate: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Purity >95% Palladium-carbon: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Pd content 5 wt%

[0081] <Abbreviation for compound> BEB: 2-bromoethylbenzene BEBS: 4-(2-bromoethyl)benzenesulfonic acid NaSS: Sodium 4-styrene sulfonate LiSS:4-Lithium Styrene Sulfonate PolyNaSS: Poly(4-styrenesulfonate sodium) PolyLiSS: Poly(4-styrene sulfonate lithium) PSS: Poly(4-styrene sulfonic acid) ClSS: 4-Styrene sulfonyl chloride ETSS: 4-Styrene sulfonate ethyl PolyETSS: Poly(4-styrene sulfonate ethyl) NPSS: Neopentyl 4-Styrene Sulfonate PolyNPSS: Poly(4-styrenesulfonate neopentyl) TfNS-Na: 4-Styrene sulfonyl (trifluoromethylsulfonylimide) sodium PolyTfNS-Na: Poly[4-styrenesulfonyl(trifluoromethylsulfonylimide) sodium] PolyTfNS-H: Poly[4-styrenesulfonyl(trifluoromethylsulfonylimide)] BVBSI-Li: Lithium bis-(4-styrenesulfonyl)imide

[0082] Example 1: Preparation of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (1) A 1L four-necked glass flask fitted with a reflux condenser, nitrogen inlet tube, thermometer insertion tube, and dropping funnel was charged with 233.80g (1.25 mol) of 2-bromoethylbenzene (manufactured by Tosoh Finechem Co., Ltd.) and 250.30g of 1,2-dichloroethane (manufactured by Tosoh Corporation). The dropping funnel was charged with a mixed solution of 111.30g (1.38 mol) of anhydrous sulfuric acid, 8.00g (0.13 mol) of acetic acid, and 250.10g of 1,2-dichloroethane. The 2-bromoethylbenzene was pre-washed with pure water, treated with cation-exchangeable Kirest Fiber® IRY-LC12 (manufactured by Kirest Co., Ltd.), and then dried with a molecular sieve to confirm that it contained less than 1 ppm of iron, 20 ppm of hydrogen bromide, and 20 ppm of moisture. 1,2-Dichloroethane was pre-dried using molecular sieves, and it was confirmed that the moisture content was 63 ppm and the iron and hydrogen bromide content were each less than 1 ppm. Under a nitrogen atmosphere, the mixture was thoroughly stirred with a magnetic stirrer, and a mixed solution of sulfuric acid anhydrous and acetic anhydrous was added dropwise over 1 hour while controlling the internal temperature to 30-40°C. After the dropwise addition, the mixture was aged at 40°C for 1 hour. The concentration of sulfuric acid anhydrous supplied to the reactor ranged from 0.00 to 12.96 wt% from the start to the end of the reaction, and the molar ratio of sulfuric acid anhydrous to 2-bromoethylbenzene was 0.00 to 1.10 (the reaction conversion rate of 2-bromoethylbenzene after aging was 97.6%).

[0083] After maturation was complete, 162.80 g of pure water was added while maintaining the internal temperature at 30-40°C. After thorough stirring, the mixture was allowed to stand, and the aqueous solution containing BEBS in the lower layer was collected using a separatory funnel. 437.32 g of concentrated BEBS aqueous solution was obtained by distilling off residual 1,2-dichloroethane and water from the aqueous solution using a rotary evaporator. The BEBS concentration measured by HPLC was 70.4 wt%, meaning the yield relative to the initial 2-bromoethylbenzene was 92.8%. Analysis of the BEBS aqueous solution by HPLC revealed a purity of 96.2% by area, and the peak area of ​​nuclear brominated BEBS was 0.01% when the peak area of ​​BEBS was set to 100%. As shown in Table 1, it is clear that the content of nuclear brominated BEBS is lower compared to Comparative Examples 1-7 shown in Table 3. Furthermore, the 2-bromoethylbenzene used was an intermediate product (industrial product) obtained in the manufacturing process of sodium styrene sulfonate (Spinomer® NaSS, manufactured by Tosoh Finechem Co., Ltd.).

[0084] Examples 2-5: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (2-5) Except for changes in the initial preparation, the composition of the dropper solution, the dropping rate, and the reaction temperature, the same raw materials as in Example 1 were used, and the BEBS aqueous solution was prepared using the same procedure. As shown in Table 1, Example 2 had a lower concentration of anhydrous sulfuric acid in the reaction system, resulting in even less nuclear brominated BEBS compared to Example 1. Example 3 had a higher concentration of anhydrous sulfuric acid in the reaction system, and Example 4 had a higher molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene, resulting in a slightly higher amount of nuclear brominated BEBS compared to Example 1. In addition, although Example 5 had a higher reaction temperature, the concentration of anhydrous sulfuric acid was low, so it is thought that the amount of nuclear brominated BEBS was at the same level as in Example 3. In any case, it is clear that the content of nuclear brominated BEBS is lower compared to Comparative Examples 1 to 7 shown in Table 3.

[0085] Examples 6-7: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (6-7) After recovering the 1,2-dichloroethane used in the reactions in Examples 1-5, it was washed with water and used as the reaction solvent. Except for these steps, the BEBS aqueous solution was synthesized using the same procedure as in Examples 4-5. As shown in Table 1, the content of nuclear brominated BEBS is higher in Examples 1-5 due to the high water content in 1,2-dichloroethane, but it is clearly lower in Comparative Examples 1, 2, 4, 6, and 7 (Table 3), which have even higher water content.

[0086] Examples 8-9: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (8-9) Except for not washing 2-bromoethylbenzene with water and drying it with molecular sieves, the BEBS aqueous solution was synthesized by performing all the same procedures as in Examples 1 to 5. As shown in Table 1, the content of nuclear brominated BEBS is higher than in Examples 1-5 due to the high hydrogen bromide content in 2-bromoethylbenzene, but it is clearly lower than in Comparative Example 3, which has high hydrogen bromide and iron content, and Comparative Examples 4 and 7 (Table 3), which have high hydrogen bromide, iron, and water content. Furthermore, the 2-bromoethylbenzene used was an intermediate product (industrial product) obtained in the manufacturing process of sodium styrene sulfonate (Spinomer® NaSS, manufactured by Tosoh Finechem Co., Ltd.).

[0087] [Table 1]

[0088] Example 10: Preparation of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (10) A 1 L glass flask equipped with a reflux condenser, nitrogen inlet tube, and thermometer insertion tube was subjected to a reaction under stirring at an internal temperature of 40-50°C. The reaction was carried out by supplying 433.50 parts by weight of a 1,2-dichloroethane solution of 2-bromoethylbenzene (a mixed solution of 233.50 parts by weight of 2-bromoethylbenzene and 200.00 parts by weight of 1,2-dichloroethane) and 419.40 parts by weight of anhydrous sulfuric acid solution of 1,2-dichloroethane (a mixed solution of 111.40 parts by weight of anhydrous sulfuric acid, 8.00 parts by weight of acetic acid, and 300.00 parts by weight of 1,2-dichloroethane) separately at a rate of 419.40 parts by weight per hour. The reaction solution was intermittently pumped out every 10 minutes, at a rate of 852.90 parts by weight per hour. The apparent residence time of the reaction solution at this time was 1 hour, the concentration of anhydrous sulfuric acid in the reactor was 12.98% by weight, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene was 1.11. The reaction conversion rate of BEB was 98.2%. Furthermore, the same 2-bromoethylbenzene and 1,2-dichloroethane used in Examples 1 to 5 were used. To 852.90 parts by weight of the extracted reaction solution, 162.80 parts by weight of pure water was added and thoroughly stirred, and the aqueous solution containing BEBS in the lower layer was recovered. By distilling off the residual 1,2-dichloroethane and water from this aqueous solution using a rotary evaporator, 438.86 parts by weight of concentrated BEBS aqueous solution was obtained. The BEBS concentration measured by HPLC was 70.4% by weight (BEB-based yield was 93.3%). Analysis of the BEBS aqueous solution by HPLC revealed, as shown in Table 2, that the purity of BEBS was 96.8% by area, and the peak area of ​​nuclear brominated BEBS was 0.01% when the peak area of ​​BEBS was set to 100. This clearly indicates that the content of nuclear brominated BEBS is lower than that of Comparative Examples 1-7 shown in Table 3.

[0089] Example 11: Preparation of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (11) In a 1 L glass flask equipped with a reflux condenser, nitrogen inlet tube, and thermometer insertion tube, 2-bromoethylbenzene was supplied separately at a rate of 233.50 parts by weight per hour, and a 1,2-dichloroethane solution of anhydrous sulfuric acid (a mixed solution of 111.60 parts by weight of anhydrous sulfuric acid, 8.00 parts by weight of acetic acid, and 500.00 parts by weight of 1,2-dichloroethane) at a rate of 619.60 parts by weight per hour. The reaction was carried out under stirring at an internal temperature of 40-50°C. The reaction solution was intermittently pumped out every 10 minutes, at a rate of 853.10 parts by weight per hour. The apparent residence time of the reaction solution at this time was 1 hour, the concentration of anhydrous sulfuric acid in the reactor was 13.00 wt%, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene was 1.11. The reaction conversion rate of BEB was 97.90%. Furthermore, the same 2-bromoethylbenzene and 1,2-dichloroethane used in Examples 1 to 5 were used. To 853.10 parts by weight of the extracted reaction solution, 163.00 parts by weight of pure water was added and thoroughly stirred, and the aqueous solution containing BEBS in the lower layer was recovered. By distilling off the residual 1,2-dichloroethane and water from this aqueous solution using a rotary evaporator, 440.65 parts by weight of a concentrated BEBS aqueous solution was obtained. The BEBS concentration measured by HPLC was 69.90 wt% (BEB-based yield was 93.01%). Analysis of the BEBS aqueous solution by HPLC revealed, as shown in Table 2, that the purity of BEBS was 96.3% by area, and the peak area of ​​nuclear brominated BEBS was 0.01% when the peak area of ​​BEBS was set to 100%, which is clearly lower than that of Comparative Examples 1-7 shown in Table 3.

[0090] [Table 2]

[0091] Comparative Example 1: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (12) A 1L four-necked glass flask fitted with a reflux condenser, nitrogen inlet tube, thermometer insertion tube, and dropping funnel was charged with 233.30 g (1.25 mol) of 2-bromoethylbenzene and 497.70 g of 1,2-dichloroethane. The dropping funnel was charged with a mixed solution of 111.30 g (1.38 mol) of anhydrous sulfuric acid and 8.00 g (0.13 mol) of acetic acid. The 2-bromoethylbenzene was pre-washed with pure water, treated with cation-exchangeable Kirest Fiber® IRY-LC12 (manufactured by Kirest Co., Ltd.), and then dried with molecular sieves. It was confirmed that the iron content was less than 1 ppm, the hydrogen bromide content 20 ppm, and the moisture content 69 ppm. Furthermore, the 1,2-dichloroethane used was recovered from the 1,2-dichloroethane used in Examples 10-11, washed with water, and contained less than 1 ppm each of iron and hydrogen bromide, with a moisture content of 2145 ppm. Under a nitrogen atmosphere, the mixture was thoroughly stirred with a magnetic stirring bar, and while controlling the internal temperature to 30-40°C, a mixed solution of anhydrous sulfuric acid and acetic anhydride was added dropwise over 1 hour. After addition, the mixture was aged at 40°C for 1 hour. The concentration of anhydrous sulfuric acid supplied to the reactor ranged from 0.00 to 13.01 wt% from the start to the end of the reaction, and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene was 0.00 to 1.11. The conversion rate of BEB was 96.4%.

[0092] After maturation was complete, 163.00 g of pure water was added while maintaining the internal temperature at 30-40°C. After thorough stirring, the mixture was allowed to stand, and the aqueous solution containing BEBS in the lower layer was collected using a separatory funnel. 420.30 g of concentrated BEBS aqueous solution was obtained by distilling off residual 1,2-dichloroethane and water from the aqueous solution using a rotary evaporator. The BEBS concentration measured by HPLC was 72.1 wt% (BEB-based yield was 91.6%). Analysis of the BEBS aqueous solution by HPLC revealed, as shown in Table 3, that the purity of BEBS was 91.3% area-wise, and the peak area of ​​nuclear brominated BEBS was 0.31% when the peak area of ​​BEBS was set to 100. This is clearly significantly higher than that of Examples 1-11 shown in Tables 1 and 2. This is thought to be due to the high water content in the reaction system, which accelerated side reactions. Furthermore, the above 2-bromoethylbenzene is sodium styrene sulfonate (spinomer NaSS manufactured by Tosoh Finechem Co., Ltd.) TM The intermediate products (industrial products) obtained in the manufacturing process of ) were used.

[0093] Comparative Example 2: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (13) A concentrated BEBS aqueous solution was synthesized by performing all the same procedures as in Comparative Example 1, except that recycled 1,2-dichloroethane with different water content was used as the reaction solvent. As shown in Table 3, the water content in 1,2-dichloroethane was even higher than in Comparative Example 1, which clearly resulted in an increased content of nuclear brominated BEBS. This is thought to be because the higher water content in the reaction system further accelerated the side reactions.

[0094] Comparative Example 3: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (14) A concentrated aqueous BEBS solution was synthesized using the same procedure as in Examples 4-5, except for washing with water, cation exchange filtration, and using 2-bromoethylbenzene that had not been dried with molecular sieves. As shown in Table 3, it is clear that the content of nuclear brominated BEBS increased significantly because the iron, hydrogen bromide, and water content in the 2-bromoethylbenzene was higher than in Examples 1-11. This is thought to be because the side reactions were further accelerated by impurities in the reaction system. Furthermore, the 2-bromoethylbenzene used was an intermediate product (industrial product) obtained in the manufacturing process of sodium styrene sulfonate (spinomer NaSS®, manufactured by Tosoh Finechem Co., Ltd.).

[0095] Comparative Example 4: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (15) A concentrated BEBS aqueous solution was synthesized by performing the same procedure as in Comparative Example 3, except that recycled 1,2-dichloroethane with a high water content was used. As shown in Table 3, the iron and hydrogen bromide content in 2-bromoethylbenzene was the same as in Comparative Example 3, but it is clear that the content of nuclear brominated BEBS increased further due to the increase in water content. This is thought to be because the side reactions were further promoted due to the synergistic effect of impurities in the reaction system.

[0096] Comparative Example 5: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (16) Except for increasing the concentration of anhydrous sulfuric acid added dropwise to the reactor and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene, the same procedure as in Examples 4 and 5 was followed to synthesize a concentrated BEBS aqueous solution. As shown in Table 3, it is clear that the content of nuclear brominated BEBS was high despite the iron, hydrogen bromide, and water content in the reaction system being the same as in Examples 1 to 11. This is thought to be because the high concentration of anhydrous sulfuric acid promoted side reactions.

[0097] Comparative Example 6: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (17) A concentrated BEBS aqueous solution was synthesized by performing the same procedure as in Comparative Example 5, except that recycled 1,2-dichloroethane with a high water content was used. As shown in Table 3, it is clear that the content of nuclear brominated BEBS increased further due to the increase in water content compared to Comparative Example 5.

[0098] Reference Example 1: Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (18) Except for lowering the concentration of anhydrous sulfuric acid in the reactor and the molar ratio of anhydrous sulfuric acid to 2-bromoethylbenzene, the same procedure as in Examples 4 and 5 was followed to synthesize a concentrated BEBS aqueous solution. As shown in Table 3, although the content of nuclear brominated BEBS is low due to the low iron, hydrogen bromide, and water content in the reaction system, the reaction conversion rate is extremely low at 35% despite the high reaction temperature, and a large amount of the raw material 2-bromoethylbenzene remains, making it clearly unsuitable as an industrial raw material (precursor) for sodium 4-styrenesulfonate.

[0099] Comparative Example 7 Production of 4-(2-bromoethyl)benzenesulfonic acid (BEBS) (18) Using a recycled product of 1,2-dichloroethane with a high water content and 2-bromoethylbenzene with a high iron content, hydrogen bromide content, and water content, similar to Comparative Examples 3 to 4, the same operations as in Reference Example 1 were performed to synthesize a concentrated BEBS aqueous solution. It is clear that even when the concentration and molar ratio of sulfuric anhydride are low, if the iron content, hydrogen bromide content, and water content in the reaction system exceed a certain concentration, the content of nuclear brominated BEBS increases. Also, since the addition amount of sulfuric anhydride is small, the reaction conversion rate is extremely low at 29.7% and is not at all suitable for practical use.

[0100]

Table 3

[0101] Example 12 Production of high-purity sodium 4-styrenesulfonate (1) <Synthesis of NaSS> Into a 2 L cylindrical glass separable flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 276.00 g of a 12% aqueous sodium hydroxide solution and 0.80 g of sodium nitrite were charged, and the temperature was raised to 70 °C while stirring. The internal temperature was maintained at 90 °C, and while stirring under a nitrogen atmosphere, 462.00 g of a 48% aqueous sodium hydroxide solution and 708.40 g of the 70.4 wt%-BEBS acid aqueous solution obtained in Example 1 were each dropped over 3 hours. After cooling the obtained NaSS slurry to 30 °C, solid-liquid separation was performed with a centrifuge to obtain 310.80 g of a wet cake of NaSS. The obtained NaSS contains impurities such as sodium bromide. Therefore, in the following examples and comparative examples, in order to quantify the amount of bound bromine, purification was performed as follows.

[0102] <Purification of NaSS> In a 1L cylindrical glass separable flask equipped with a reflux condenser, nitrogen inlet tube, and stirrer, 6.16g of sodium hydroxide, 293.00g of pure water, 0.28g of sodium nitrite, and 308.00g of the above-mentioned NaSS were charged and stirred at 60°C for 1 hour under a nitrogen atmosphere. After cooling to room temperature over 3 hours, solid-liquid separation was performed using a centrifuge to obtain 272.10g of a moist cake of purified NaSS. Approximately 100 g of the purified NaSS cake obtained above was dissolved in pure water to make a 5 wt% aqueous solution (based on purity), and an aqueous styrene sulfonic acid solution was obtained by passing the solution through a strongly acidic cation exchange resin column (Organo Amberlite IR-120B, hydrochloric acid regenerated) and a strongly basic anion exchange resin column (Organo Amberlite IRA-402BL, sodium hydroxide regenerated) in that order. Since styrene sulfonic acid after cation exchange is prone to spontaneous polymerization, the aqueous solution after column distillation was kept below 5°C, and immediately neutralized with sodium hydroxide after anion exchange. The aqueous solution was concentrated using a rotary evaporator, and the precipitated crystals were filtered off and vacuum-dried at 60°C for 5 hours to obtain 64.60 g of high-purity NaSS crystals with a purity of 99.5 wt% and a moisture content of 0.5 wt%. The bromine content in the high-purity NaSS, as determined by ion chromatography, was less than 1 ppm, i.e., the inorganic (unbound) bromine content. Furthermore, HPLC analysis of organic impurities such as isomers that may be present in the above-mentioned high-purity NaSS crystals revealed the following: (a) sodium orthostyrene sulfonate 0.00%, (b) sodium 4-(2-bromoethyl)benzenesulfonate 0.00%, (c) sodium metastyrene sulfonate 0.01%, (d) sodium bromostyrene sulfonate 0.01%, and (e) sodium 4-(2-hydroxyethyl)benzenesulfonate 0.00% (however, this is the area ratio when the sum of the HPLC peak areas of the above organic impurities and NaSS is set to 100). From the molecular weight of NaSS (206.2 g / mol), the molecular weight of sodium bromostyrenesulfonate (285.1 g / mol), the atomic weight of Br (79.9 g / mol), and the above HPLC area ratio (assuming it is approximately the molar ratio), the bromine content derived from sodium bromostyrenesulfonate in high-purity NaSS can be estimated as follows. 1,000,000×79.9×0.01 / (285.1×0.01 + 206.2×99.99) ≒ 39 ppm On the other hand, the total bromine content of the high-purity NaSS, that is, the result of quantifying the bound bromine by combustion decomposition ion chromatography, was 108 ppm, which was much higher than the above value. That is, it was suggested that there was a quantitative error due to the extremely small peak of the above sodium bromostyrenesulfonate, or the existence of bound bromine other than sodium bromostyrenesulfonate, such as positional isomers. However, compared with Comparative Examples 8 to 11, the total bromine amount was clearly less (Table 4). This is considered to be because BEBS with a low content of nuclear brominated BEBS was used as the precursor. Furthermore, by the following method, the high-purity NaSS was polymerized to induce PSS, and the change in bromine ion concentration over time (the existence of unstable bound bromine) was confirmed.

[0103] <Synthesis of PolyNaSS> In a 500 ml glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 250.00 g of pure water, 30.02 g of the high-purity NaSS obtained above, and 1.00 g of a water-soluble azo radical polymerization initiator V-50 were collected and dissolved at room temperature. Subsequently, after repeated deoxygenation by aspirator suction and nitrogen introduction, polymerization was carried out in a 60 °C water bath with stirring for 24 hours under a nitrogen atmosphere. At this point, the polymerization conversion rate of NaSS determined by GPC was 100%. Subsequently, under a nitrogen stream, 1.64 g of a 48 wt% aqueous sodium hydroxide solution was added, and stirring was continued at 60 °C for 24 hours while maintaining the solution pH ≥ 13. The number average molecular weight Mn of polyNaSS determined by GPC was 114,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.50).

[0104] <Preparation and Stability Confirmation of PSS> The obtained aqueous poly-NaSS solution was treated with an ultrafiltration module (Vivaflo 200 manufactured by Sartorius, molecular weight cut-off 50,000), and then passed through a strongly acidic cation exchange resin column (Amberlite IR-120B manufactured by Organo, regenerated with hydrochloric acid) and a strongly basic anion exchange resin column (Amberlite IRA-402BL manufactured by Organo, regenerated with sodium hydroxide) in that order to obtain an aqueous PSS solution. About 1 g of the aqueous solution was precisely weighed, vacuum dried at 100 °C for 3 hours to calculate the resin content, and then the resin content was adjusted with pure water to obtain 230.01 g of a 10.00 wt% aqueous polystyrene sulfonic acid solution. The number average molecular weight of PSS was 114,000, the weight average molecular weight was 282,000 (Mw / Mn = 2.47), the bromine ion concentration determined by ion chromatography was less than 1 ppm, and the sodium content determined by ICP-AES was less than 1 ppm. That is, free (non-bonded) bromine was sufficiently removed. On the other hand, about 10 g of the aqueous PSS solution was collected, vacuum dried at 110 °C for 3 hours to obtain a PSS solid, and as a result of analyzing the total bromine content by decomposition combustion ion chromatography, it was 111 ppm. The total chlorine content in the PSS solid was less than 1 ppm. The above aqueous PSS solution was sealed in small portions in glass sample bottles and aged in an oven at 70 °C. As a result of tracking the change in bromine ion concentration by ion chromatography, as shown in Table 4, it is clear that the increase in bromine ions over time is significantly suppressed compared to Comparative Examples 8 to 11. This is considered to be because the amount of bound bromine contained in NaSS is small, that is, the nuclear brominated compounds that may be contained in the precursor BEBS were reduced. In addition, as long as BEBS is used as the precursor, the possibility of chlorine remaining in NaSS and its polymer is low. On the other hand, when 4-(2-chloroethyl)benzenesulfonic acid (for example, JP-A-9-40633) is used as the precursor, it is considered that inorganic and organic chlorine may remain, similar to BEBS.

[0105] Example 13 Production of High-Purity Sodium 4-Styrenesulfonate (2) <Synthesis of NaSS> Reaction and the like were carried out under the same conditions as in Example 12 in terms of charged weight and the like, except that the 69.9 wt%-BEBS aqueous solution obtained in Example 2 above was used, and 302.20 g of a wet cake of NaSS was obtained.

[0106] <Purification of NaSS> Purification was carried out under the same conditions as in Example 12 in all respects, except that the wet cake of NaSS obtained above was used, and 66.02 g of dry crystals of high-purity NaSS were obtained. The purity was 99.5 wt%, the water content was 0.5 wt%, and the bromine content in the high-purity NaSS, that is, the inorganic bromine content analyzed by aqueous solution, was less than 1 ppm, and the total bromine content was 46 ppm. It is clear that the total bromine amount is less compared to Comparative Examples 8 to 11 (Table 4). This is considered to be because BEBS with a low content of nuclear brominated BEBS was used as the precursor. Subsequently, in the same manner as in Example 12, NaSS was polymerized to induce PSS, and the change in bromine ion concentration over time was confirmed.

[0107] <Synthesis of poly-NaSS> Polymerization of NaSS was carried out under the same conditions as in Example 12 in all respects such as charged weight, except that the high-purity NaSS crystals obtained above were used, and an aqueous solution of poly-NaSS with a number average molecular weight Mn of 112,000 and a weight average molecular weight Mw of 281,000 (Mw / Mn = 2.51) was obtained.

[0108] <Preparation and stability confirmation of PSS> Ultrafiltration and ion exchange treatment were carried out in the same manner as in Example 12 in all respects, except that the aqueous solution of poly-NaSS obtained above was used, and 238.96 g of a 10.00 wt% PSS aqueous solution was obtained. The number average molecular weight was 112,000, the weight average molecular weight was 281,000 (Mw / Mn = 2.51), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. PSS solid was obtained in the same manner as in Example 12, and as a result of analyzing the total bromine content, it was 47 ppm, which was decreased compared to Example 12. In addition, the total chlorine content in the PSS solid was less than 1 ppm. Subsequently, similar to Example 12, the above PSS aqueous solution was aged, and as a result of tracking the change in bromine ion concentration, as shown in Table 4, it was clear that the increase in bromine ions over time was significantly suppressed compared to Comparative Examples 8 to 11. It is considered that this is because the amount of bound bromine contained in NaSS is small, that is, because the nuclear brominated compound that may be contained in BEBS, which is the precursor, was reduced.

[0109] Example 14 Production of High-Purity Sodium 4-Styrenesulfonate (3) <Synthesis of NaSS> Reactions and the like were carried out under the same conditions as in Example 12 in all respects such as the charged weight, except that the 71.3 wt%-BEBS aqueous solution obtained in Example 7 above was used, and 316.10 g of a wet cake of NaSS was obtained.

[0110] <Purification of NaSS> Purification was carried out under the same conditions as in Example 12 in all respects such as the charged weight, except that the NaSS obtained above was used, and 63.60 g of dry crystals of high-purity NaSS were obtained. The purity was 99.5 wt%, the water content was 0.5 wt%, the bromine content in the high-purity NaSS, that is, the inorganic bromine content analyzed in an aqueous solution, was less than 1 ppm, and the total bromine content was 302 ppm. Because BEBS with a large amount of nuclear brominated BEBS was used, the total bromine content was higher compared to Examples 12 and 13, but it was clearly less compared to Comparative Examples 8 to 11 (Table 4). Subsequently, similar to Example 12, NaSS was polymerized to induce PSS, and the change in bromine ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0111] <Synthesis of PolyNaSS> NaSS was polymerized under the same conditions as in Example 12 in all respects such as the charged weight, except that the high-purity NaSS crystals obtained above were used, and an aqueous solution of polyNaSS with a number average molecular weight Mn of 113,000 and a weight average molecular weight Mw of 283,000 (Mw / Mn = 2.50) was obtained.

[0112] <Preparation and Stability Confirmation of PSS> Apart from using the poly-NaSS aqueous solution obtained above, ultrafiltration and ion exchange treatment were performed in the same manner as in Example 12 to obtain 241.95 g of 10.00 wt% PSS aqueous solution. The number average molecular weight was 113,000, the weight average molecular weight was 283,000 (Mw / Mn=2.50), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. PSS solid was obtained in the same manner as in Example 12, and the total bromine content was analyzed to be 315 ppm, and the total chlorine content was less than 1 ppm. Next, similar to Example 12, the above PSS aqueous solution was aged, and the change in bromide ion concentration was tracked. As shown in Table 4, it is clear that the increase in bromide ions over time was significantly suppressed compared to Comparative Examples 8-11. This is thought to be because the amount of bound bromine contained in NaSS is small, that is, the amount of nucleobrominated products that may be contained in the precursor BEBS was reduced.

[0113] Example 15: Production of ethyl styrene sulfonate (ETSS) (1) <Synthesis of 4-Styrene sulfonyl chloride (ClSS)> In a 3 L four-necked glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 300.00 g (1.45 mol) of high-purity NaSS crystals obtained under the conditions of Example 12, 600.00 g of toluene, 106.00 g (1.44 mol) of N,N-dimethylformamide, and 0.12 g (0.1 mmol) of the antioxidant Irganox (registered trademark) 1010 were charged, and the mixture was stirred for 30 minutes under a nitrogen atmosphere while maintaining the internal temperature at 0 °C. Subsequently, while controlling the internal temperature so that it did not exceed 5 °C, 236.0 g (1.94 mol) of thionyl chloride was added dropwise over 2 hours, and stirring was continued for another 3 hours. Next, while controlling the internal temperature so that it did not exceed 20 °C, 750.00 g of pure water was added, and after thorough stirring, the mixture was allowed to stand, and the separated aqueous layer was discarded. 750.00 g of a 20 wt% aqueous sodium chloride solution was added to the remaining organic layer, and after thorough stirring, the mixture was allowed to stand, and the separated aqueous layer was discarded. Then, while controlling the internal temperature so that it did not exceed 10 °C, nitrogen was blown into the reaction solution for 12 hours while stirring to remove components derived from thionyl chloride. Thereafter, 750.00 g of pure water was added to the organic layer again, and the washing of the organic layer was repeated until the electrical conductivity of the aqueous layer became 1 μS / cm or less, and a 760.00 g ClSS solution was obtained. 1 The ClSS concentration determined by 1H-NMR was 36.2 wt%. That is, the pure ClSS content was 275.10 g (1.36 mol), and the yield based on the charged NaSS was 94%.

[0114] <Synthesis of ETSS> In a 200 ml four-necked glass flask equipped with a reflux condenser, nitrogen inlet tube, and stirrer, 38.5 g (0.069 mol) of the ClSS solution obtained above, 9.2 g (0.200 mol) of ethanol, and 6 milligrams (0.005 mmol) of the antioxidant Irganox® 1010 were charged, and the internal temperature was controlled to not exceed 0°C. An aqueous solution consisting of 15.4 g (0.132 mol) of 48 wt% potassium hydroxide aqueous solution and 9.2 g of pure water was added dropwise over 5 hours, and the mixture was aged for another 5 hours to esterify. During this time, the internal temperature was controlled to not exceed 20°C. Subsequently, 100.00 g of pure water was added and stirred, then allowed to stand to discard the aqueous layer containing potassium chloride, etc., and the mixture was further washed with 20 wt% saline solution. Pure water was added again and the aqueous layer was washed until the ionic conductivity of the aqueous layer was 1.00 μS / cm or less, and the organic layer was recovered. Toluene was removed under reduced pressure at 40°C using a rotary evaporator to obtain 12.01 g of ETSS. The area-based purity determined by gas chromatography was 94.00% (the main impurity being toluene present in the ClSS solution), and the ClSS-based yield was 77%. The bromine content in the ETSS determined by ion chromatography, i.e., the inorganic bromine extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 84 ppm, clearly showing a lower bromine content compared to Comparative Examples 12-14 (Table 4). This is thought to be because NaSS derived from BEBS with a low nuclear brominated BEBS content was used as the raw material. Next, ETSS was polymerized using the following method to induce PSS, and the change in bromine ion concentration over time (the presence of unstable bound bromine) was confirmed.

[0115] <Synthesis of PolyETSS> In a 300 ml four-necked glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 10.75 g (46.80 mmol) of ETSS obtained above, 40.00 g of anisole, 0.15 g (0.94 mmol) of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), and 0.40 g (2.39 mmol) of azobisisobutyronitrile were collected. After that, while stirring with a magnetic stir bar, the mixture was repeatedly degassed and nitrogen was introduced under reduced pressure to deoxygenate it. Then, under a nitrogen atmosphere, polymerization was carried out at 110 °C for 20 hours and subsequently at 135 °C for 2 hours to prepare poly-ETSS.

[0116] <Preparation and Stability Confirmation of PSS> After allowing the above reaction solution to cool to 100 °C, 75.00 g (93.75 mmol) of a 5 wt% aqueous sodium hydroxide solution was added, and after stirring for 5 hours, the insoluble matter was filtered off. The aqueous layer containing poly-NaSS was recovered by liquid separation operation. While vigorously stirring the aqueous solution, it was slowly dropped into 2 L of acetone, and the precipitated polymer was vacuum dried at 110 °C for 10 hours to recover 3.67 g of poly-NaSS (yield 38% based on ETSS). The number average molecular weight of poly-NaSS was 9,000, and the weight average molecular weight was 11,000 (Mw / Mn = 1.22). The poly-NaSS was dissolved in pure water and treated with an ultrafiltration module (Vivaflo 200 manufactured by Sartorius, molecular weight cut-off 5,000), and then ion exchange treatment was carried out in the same manner as in Example 12 to obtain 26.77 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 9,000, the weight average molecular weight was 11,000 (Mw / Mn = 1.22), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. That is, it can be said that free bromine not bound to the polymer was sufficiently removed by the ion exchange treatment. Similar to Example 12, the above PSS was aged, and as a result of tracking the change in bromide ion concentration, as shown in Table 4, it is clear that the increase in bromide ions over time was significantly suppressed compared to Comparative Examples 12 to 14. It is considered that this is because the amount of bound bromine contained in ETSS is small, that is, the nuclear brominated species that may be contained in BEBS, the precursor, was reduced.

[0117] Example 16 Production of Ethyl Styrenesulfonate (ETSS) (2) <Synthesis of ClSS> Using the high-purity NaSS crystals obtained in Example 13 and reducing the scale to 1 / 10, 75.00 g of ClSS solution was obtained under the same conditions as in Example 15. 1 The ClSS concentration determined by 1H-NMR was 35.9 wt%. That is, the pure ClSS content was 26.93 g, and the yield based on the charged NaSS was 92%.

[0118] <Synthesis of ETSS> Using the ClSS obtained above, ETSS was synthesized under the same conditions as in Example 15, and 11.90 g of ETSS was obtained. The purity based on the area% determined by gas chromatography was 95.00% (the main impurity was toluene contained in the ClSS solution), and the yield based on ClSS was 78%. The bromine content in the ETSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 51 ppm. It is clear that the bromine content is less compared to Comparative Examples 12 to 14 (Table 4). This is presumably because NaSS derived from BEBS with a low content of nuclear brominated BEBS was used as the raw material. Subsequently, in the same manner as in Example 15, ETSS was polymerized to induce PSS, and the change in bromine ion concentration over time was confirmed.[[ID=X]] [[ID=X]]

[0119] [[ID=X]] <Synthesis of PolyETSS> Using the ETSS obtained above, ETSS was polymerized under the same conditions as in Example 15 to prepare polyETSS.

[0120] <Preparation of PSS and Confirmation of Stability>。 Using the polyETSS obtained above, the same operations as in Example 15 were performed to obtain 26.98 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 9,000, the weight average molecular weight was 11,000 (Mw / Mn = 1.22), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above PSS aqueous solution was aged, and as a result of tracking the change in bromide ion concentration, as shown in Table 4, it was clear that the increase in bromide ions over time was significantly suppressed compared to Comparative Examples 12 to 14. Since the amount of bound bromine contained in ETSS is small, it is considered that the nuclear brominated product that may be contained in BEBS, which is the precursor, was reduced.

[0121] Example 17 Production of Ethyl Styrenesulfonate (ETSS) (3) <Synthesis of ClSS> Reactions and the like were carried out under the same conditions as in Example 16 in all respects such as charged weight, except that the high-purity NaSS crystals obtained in Example 14 were used, and a 76.30 g ClSS solution was obtained. 1 The ClSS concentration determined by 1H-NMR was 35.50% by weight. That is, the pure ClSS content was 27.09 g, and the yield based on the charged NaSS was 92%.

[0122] <Synthesis of ETSS> Reactions and the like were carried out under the same conditions as in Example 16 in all respects, except that the ClSS obtained above was used, and 12.10 g of ETSS was obtained. The purity based on area% determined by gas chromatography was 95.00% (the main impurity was toluene contained in the ClSS solution), and the yield based on ClSS was 80%. The bromine content in the ETSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 338 ppm. It was clear that the bromine content was less compared to Comparative Examples 12 to 14 (Table 4). However, since BEBS with a large amount of nuclear brominated BEBS was used as the high-purity NaSS raw material, the total bromine content increased compared to Examples 15 and 16. Subsequently, similar to Example 15, ETSS was polymerized to induce PSS, and the change in bromide ion concentration over time was confirmed.

[0123] <Synthesis of PolyETSS>​​​​ <Preparation and Stability Confirmation of PSS> Except for using the poly-ETSS obtained above, 26.65 g of a 10.00 wt% PSS aqueous solution was obtained by the same operation as in Example 16. The number average molecular weight was 9,000, the weight average molecular weight was 11,000 (Mw / Mn = 1.22), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 15, the above PSS aqueous solution was aged and the change in bromine ion concentration was traced. As shown in Table 4, it was clear that the increase in bromine ions over time was significantly suppressed compared to Comparative Examples 12 to 14. This is presumably because the amount of bound bromine contained in ETSS is small, that is, the nuclear brominated species that may be contained in BEBS, which is the precursor, was reduced.

[0125] Example 18 Production of High-Purity Neopentyl Styrenesulfonate (NPSS) (1) <Synthesis of NPSS> 54.00 g (0.60 mol) of neopentyl alcohol and 171.3 g (2.14 mol) of pyridine were placed in a 1 L glass four-neck flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, and stirred and dissolved with a magnetic stirrer while maintaining the internal temperature at 0 °C. While controlling the internal temperature so that it did not exceed 0 °C, 323.21 g (0.58 mol) of the 36.20 wt%-ClSS solution obtained in Example 15 was added dropwise to the reactor over 2.5 hours and reacted. After distilling off the excess pyridine and toluene using an evaporator, the contents were poured into 1 L of hexane and cooled to -15 °C to recover white crystals. The white crystals were recrystallized and purified using a mixed solvent of hexane:toluene = 1:1 volume ratio to obtain 37.5 g of white crystals of NPSS. The yield based on ClSS was 25%, 1 The purity determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 97.5%. The bromine content in the NPSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 122 ppm, which was clearly less bromine content compared to Comparative Example 15 (Table 4). This is presumably because NaSS derived from BEBS with a low content of nuclear brominated BEBS was used as a raw material. Furthermore, NPSS was polymerized to induce PSS by the following method, and the change in bromine ion concentration (presence of unstable bound bromine) over time was confirmed.

[0126] <Synthesis of poly NPSS> Into a 200 ml four-necked glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 10.00 g (39.32 mmol) of NPSS obtained above, 40.00 g of N,N-dimethylformamide, and 325 mg (1.98 mmol) of azobisisobutyronitrile were collected. After deoxygenation by repeating evacuation and nitrogen introduction while stirring, polymerization was carried out at 70 °C for 25 hours under a nitrogen atmosphere. While vigorously stirring the polymerization solution, it was slowly dropped into 1 L of hexane to isolate poly NPSS. The polymer was dissolved again in chloroform and dropped into hexane, which is a poor solvent, to purify the polymer. The wet polymer was vacuum dried at 90 °C for 10 hours to recover 7.10 g of poly NPSS (yield 71% based on NPSS). The number average molecular weight Mn measured by GPC was 18,000, and the weight average molecular weight Mw was 45,000 (Mw / Mn = 2.50).

[0127] <Synthesis and stability confirmation of PSS> After dissolving 7.10 g of the poly NPSS obtained above in 60.0 g of dichloromethane, 14.76 g of trimethylsilyl iodide (2.5 equivalents relative to the sulfonic acid neopentyl group) was added, and the mixture was stirred at room temperature for 4 hours. Subsequently, dichloromethane was distilled off under reduced pressure, and the recovered polymer was put into a mixed solution consisting of 40 ml of 1N hydrochloric acid and 40 ml of methanol. After stirring at room temperature for 2 hours, the solvent was distilled off under reduced pressure to obtain PSS. The obtained PSS was dissolved in ion-exchanged water, treated with an ultrafiltration module (Vivaflo 200 manufactured by Sartorius, molecular weight cut-off 10,000), and then subjected to ion-exchange treatment in the same manner as in Example 15 to obtain 56.80 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 18,000, the weight average molecular weight was 45,000 (Mw / Mn = 2.50), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. That is, it can be said that free bromine compounds not bound to the polymer were sufficiently removed by the purification treatment. Similar to Example 12, the above PSS aqueous solution was aged and the change in bromide ion concentration was tracked. As shown in Table 4, it is clear that the increase in bromide ions over time is significantly suppressed compared to Comparative Example 15. This is presumably because the amount of bound bromine in NPSS is small, that is, the nuclear brominated compounds that may be contained in the precursor BEBS are reduced.

[0128] Example 19 Production of High-Purity Sodium 4-Styrenesulfonyl(trifluoromethylsulfonylimide) (TfNS-Na) (1) <Synthesis of TfNS-Na> 14.92 g (98.07 mmol) of trifluoromethanesulfonamide, 116.00 g of ethyl acetate, 0.62 g (4.97 mmol) of 4-dimethylaminopyridine, and 1.02 g of tert-butylcatechol were placed in a 500 ml four-necked glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer. After stirring and dissolving at room temperature, 21.24 g (198.39 mmol) of sodium carbonate was added. After raising the internal temperature to 50°C, 54.88 g (98.03 mmol) of the 36.2 wt%-ClSS solution obtained in Example 15 was added dropwise over 1 hour while maintaining the internal temperature at 50 - 60°C. After further aging at 60°C for 4 hours, it was cooled to 35°C, 90.00 g of ion-exchanged water was added, and it was stirred vigorously. After standing, it was separated, and the aqueous layer containing sodium chloride was discarded. Further, 50.00 g of a 20 wt% aqueous sodium chloride solution was added, and it was stirred vigorously. After standing, it was separated, and the aqueous layer was discarded. 60.00 g of toluene, a non-solvent, was added to the organic layer to form a homogeneous solution, and then ethyl acetate, a good solvent, was distilled off under reduced pressure. The precipitated crystals were filtered off and vacuum dried at room temperature for 24 hours to obtain 25.34 g (yield 73%) of TfNS-Na.

[0129] <Purification of TfNS-Na> The TfNS-Na obtained above was dissolved in deionized water to prepare a 5% by weight aqueous solution. While taking care to ensure that the temperature of the aqueous solution did not exceed 10°C, a cation and anion exchange treatment was performed in the same manner as in Example 12 to obtain an aqueous TfNS-H solution. Since TfNS-H after cation exchange is prone to spontaneous polymerization, the aqueous solution after column effluent was kept below 5°C, and immediately after anion exchange it was neutralized with sodium hydroxide. The water was removed from the aqueous solution using a rotary evaporator, and the precipitated crystals were filtered off. High-purity TfNS-Na 21.30 g was obtained by vacuum drying at 60°C for 5 hours. 1 The purity determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 99.5% by weight, the water content was 0.5% by weight, the bromine content determined by ion chromatography, i.e., the inorganic bromine content analyzed in aqueous solution, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 101 ppm. It is clear that the total bromine content is lower compared to Comparative Example 16 (Table 4). This is thought to be because sodium styrenesulfonate derived from BEBS with a low nuclear brominated BEBS content was used as the raw material. Furthermore, TfNS-Na was polymerized using the following method, and the change in bromine ion concentration over time (indicating the presence of unstable bound bromine) was confirmed.

[0130] <Synthesis of polyTfNS-H> Deoxygenation was carried out by repeatedly applying nitrogen after reducing pressure in an aspirator to each of the following methods: dissolving 20.00 g (58.71 mmol) of TfNS-Na obtained above in 90.00 g of deionized water to prepare a monomer aqueous solution, and dissolving 0.10 g (0.44 mmol) of ammonium persulfate in 10.00 g of deionized water to prepare a radical polymerization initiator aqueous solution. Polymerization was carried out at a bath temperature of 85°C while simultaneously adding the above aqueous solutions dropwise over 3 hours to a 200 ml four-necked glass flask equipped with a reflux condenser, nitrogen inlet tube, and stirrer. The mixture was then aged at 85°C for a further 2 hours. The polymerization conversion rate measured by GPC was 98.7%, the number-average molecular weight was 35,000, and the weight-average molecular weight was 82,000 (Mw / Mn=2.34). By subjecting the aqueous poly(TfNS-Na) solution to ultrafiltration and ion exchange treatment in the same manner as in Example 18, 146.88 g of a 10.00 wt% aqueous poly(TfNS-H) solution was obtained. The bromide ion concentration determined by ion chromatography was less than 1 ppm, and the sodium content determined by ICP-AES was less than 1 ppm.

[0131] <Stability of poly(TfNS-H)> Similar to Example 12, as a result of tracking the change in bromide ion concentration by ion chromatography, as shown in Table 4, it is clear that the increase in bromide ions over time is significantly suppressed compared to Comparative Example 16. This is presumably because the amount of bound bromine in TfNS-Na is small, that is, because the nuclear brominated species that may be contained in BEBS, the precursor, has been reduced.

[0132] Example 20 Production of High-Purity Lithium 4-Styrenesulfonate (LiSS) (1) <Synthesis of LiSS> A 1 L cylindrical glass separable flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer was charged with 130.60 g (3.23 mol) of lithium hydroxide monohydrate, 0.60 g (0.009 mol) of sodium nitrite, and 351.00 g of ion-exchanged water, and the temperature was raised to 70 °C while stirring. The internal temperature was maintained at 90 °C, and 457.75 g (1.21 mol) of the 70.20 wt%-BEBS aqueous solution obtained in Example 4 above was added dropwise over 1 hour while stirring under a nitrogen atmosphere, and the mixture was further aged for 0.5 hour. After cooling the reaction solution to 20 °C over 3 hours, it was aged for 2 hours as it was, and the resulting slurry of LiSS was separated by solid-liquid separation using a centrifuge to obtain 199.70 g (0.89 mol) of a wet cake of LiSS with a purity of 85.0%.

[0133] <Purification of LiSS> 2 L of the above wet cake and 1 L of acetone were taken in a 2 L glass beaker, stirred at room temperature for 1 hour, and then the wet LiSS was recovered using a Buchner funnel. The recovered wet LiSS was put into 1 L of acetone again, stirred at room temperature for 1 hour, and then the wet LiSS was recovered using a Buchner funnel. Further, it was vacuum dried at 60 °C for 10 hours in an oven to obtain 73.50 g of high purity LiSS. The purity was 98.7 wt%, the moisture content was 1.30 wt%, and the bromine content in the high purity LiSS determined by ion chromatography, that is, the inorganic bromine content analyzed in an aqueous solution, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 296 ppm. It is clear that the total bromine content is less than that of Comparative Example 17 (Table 4). This is presumably because BEBS with a low content of nuclear brominated BEBS was used as the raw material. Furthermore, LiSS was polymerized to PSS by the following method, and the change in bromine ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0134] <Synthesis of poly LiSS> 250.00 g of pure water, 30.00 g (0.16 mol) of the high purity LiSS obtained above, and 2.10 g (0.008 mol) of a water-soluble azo radical polymerization initiator V-50 were taken in a 500 ml glass flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, and dissolved at room temperature. Subsequently, after repeated deoxygenation by aspirator suction and nitrogen introduction, polymerization was carried out in a 60 °C water bath with stirring for 24 hours under a nitrogen atmosphere. At this point, the polymerization conversion rate of LiSS was 100%. Subsequently, 1.70 g of a​​​​​​​Similar to Example 12, as a result of tracking the bromine ion concentration by ion chromatography, as shown in Table 4, it is clear that the increase in bromine ions over time is significantly suppressed compared to Comparative Example 17. This is presumably because the amount of bound bromine in LiSS is small, that is, because the nuclear brominated compounds that may be contained in BEBS, the precursor, are reduced.

[0136] Example 21 Production of Sodium Styrenesulfonate / Styrene Copolymer (ST-3510) <Synthesis of NaSS / Styrene Copolymer> 26.60 g of crude NaSS obtained in Example 12 (purity 88.5%, 114.17 mmol), 121.00 g of ion-exchanged water, 69.89 g of 2-propanol, 6.37 g of styrene (60.55 mmol), and 0.92 g of water-soluble azo radical polymerization initiator V-50 (3.36 mmol) were charged into a 500 ml three-necked flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, dissolved, and deoxygenated by repeating vacuum degassing and nitrogen introduction. Then, the flask was immersed in a warm bath at 60 °C and polymerized for 25 hours with stirring. The polymerization conversion rate of sodium styrenesulfonate was 100%, the polymerization conversion rate of styrene was 98%, the number average molecular weight was 33,000, the weight average molecular weight was 74,000 (Mw / Mn = 2.24), and the copolymer composition calculated from the polymerization conversion rate was a NaSS / St = 66 / 34 molar ratio. Isopropanol and water were distilled off under reduced pressure using a rotary evaporator to obtain a 15 wt% polymer aqueous solution.

[0137] <Synthesis of Styrenesulfonic Acid / Styrene Copolymer> The above NaSS / styrene copolymer was subjected to ultrafiltration and ion exchange treatment under the same conditions as in Example 19 to obtain 231.28 g of a 10.0 wt% aqueous solution of styrenesulfonic acid / styrene copolymer. The bromine ion concentration was less than 1 ppm and the sodium content was less than 1 ppm.

[0138] <Stability of Styrenesulfonic Acid / Styrene Copolymer> Similar to Example 12, the styrenesulfonic acid / styrene copolymer aqueous solution obtained above was aged, and the change in bromide ion concentration was traced. As a result, as shown in Table 4, it was revealed that it has the same stability as Example 12. It is considered that this is because the amount of bound bromine contained in NaSS is small, that is, the nuclear brominated compound that may be contained in BEBS as a precursor is reduced.

[0139] Example 22 Production of sodium styrenesulfonate / methacrylic acid copolymer <Synthesis of NaSS / methacrylic acid copolymer> Into a 500 ml three-necked flask equipped with a reflux condenser, a nitrogen inlet tube, and a stirrer, 35.00 g (purity 88.5%, mmol) of the unpurified NaSS obtained in Example 12, 250.00 g of ion-exchanged water, 3.35 g (38.52 mmol) of methacrylic acid, and 2.50 g (9.13 mmol) of a water-soluble azo radical polymerization initiator V-50 were charged and dissolved, and deaeration was carried out by repeating reduced-pressure degassing and nitrogen introduction. Then, the flask was immersed in a warm bath at 60 °C and polymerized for 25 hours while stirring. The polymerization conversion rate of NaSS was 100%, the polymerization conversion rate of methacrylic acid was 96%, the number average molecular weight was 46,000, the weight average molecular weight was 129,000 (Mw / Mn = 2.80), and the copolymer composition calculated from the polymerization conversion rate was a NaSS / MAA = 80 / 20 molar ratio. Water was distilled off under reduced pressure using a rotary evaporator to obtain a 15 wt% polymer aqueous solution.

[0140] <Synthesis of styrenesulfonic acid / methacrylic acid copolymer> The above NaSS / methacrylic acid copolymer was subjected to ultrafiltration and ion exchange treatment under the same conditions as in Example 19 to obtain 262.26 g of a 10.0 wt% aqueous solution of styrenesulfonic acid / methacrylic acid copolymer. The bromide ion concentration was less than 1 ppm and the sodium content was less than 1 ppm.

[0141] <Stability of styrenesulfonic acid / methacrylic acid copolymer> Similar to Example 12, the aqueous solution of the styrenesulfonic acid / methacrylic acid copolymer was aged, and the change in bromide ion concentration was traced. As a result, as shown in Table 4, it was revealed that it has the same stability as Example 12. Since the amount of bound bromine contained in NaSS is small, it is considered that the nuclear brominated compound, which may be contained in BEBS as a precursor, was reduced.

[0142] Example 23 Production of Lithium Bis-(4-styrenesulfonyl)imide (BVBSI-Li) (1) <Synthesis of 4-styrenesulfonamide> Into a 300 mL glass flask reactor equipped with a reflux condenser, a nitrogen inlet tube, and a dropping tube, 30.0 g (54.20 mmol) of the ClSS solution synthesized in Example 15 and 30.00 g of tetrahydrofuran were collected and stirred and dissolved at room temperature. This solution was cooled to 0 °C, and 30.00 g (493.25 mmol) of a 28% aqueous ammonia solution (manufactured by Kishida Chemical) was dropped over 1 hour. After the dropping was completed, the mixture was stirred at room temperature for 2 hours. After the reaction was completed, 30.00 g of ion-exchanged water and 30.00 g of ethyl acetate were added, and a liquid separation operation was performed to obtain an organic layer containing 4-styrenesulfonamide. This organic layer was concentrated to obtain 6.05 g (yield 65%) of a white solid of 4-styrenesulfonamide.

[0143] <Synthesis of BVBSI-Li> Into a 100 ml glass flask reactor equipped with a reflux condenser, a nitrogen inlet tube, and a dropping tube, 5.00 g (28.96 mmol) of 4-styrenesulfonamide obtained above, 0.55 g (65.72 mmol) of lithium hydride, and 30.00 g of dehydrated tetrahydrofuran were collected and stirred at room temperature under a nitrogen atmosphere. Next, 16.00 g (28.59 mmol) of the ClSS solution synthesized in Example 15 was dropped into the above slurry solution at room temperature. After the dropping was completed, the temperature was raised to 60 °C and stirred for 3 hours. The solvent was distilled off with a rotary evaporator to recover a white solid. After washing the white solid with diethyl ether, it was recrystallized with methanol to obtain 6.74 g of white crystals of BVBSI-Li, a yield of 64% based on ClSS. 1The purity determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 94.0%. The bromine content in the high-purity BVBSI-Li determined by ion chromatography, that is, the inorganic bromine content analyzed in an aqueous solution, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 121 ppm.

[0144] Synthesis Example 2 Production of Lithium Polystyrene Sulfonate Crosslinked Product 2.00 g (10.21 mmol) of LiSS obtained in Example 20, 0.50 g (1.06 mmol) of BVBSI-Li obtained in Example 23, and 0.005 g (0.018 mmol) of water-soluble azo-based polymerization initiator V-50 were dissolved in 3.50 g of ion-exchanged water to prepare a mixed monomer solution. The monomer solution was dropped onto a transparent glass plate (thickness 1.5 mm, 5 cm × 5 cm square) on which a PET film spacer (thickness 0.5 mm, with a 3 cm × 3 cm window cut out in the center of the 5 cm × 5 cm square film) was placed. Then, the same transparent glass plate was overlaid from above to exclude the excess monomer solution. After fixing the two glass plates with metal clips, LED light with a wavelength of 365 nm was irradiated for 3.0 hours from a distance of 5 cm in the direction perpendicular to the glass surface. The illuminance at a position 5 cm away from the LED irradiation surface in the vertical direction was 100 mW / cm 2 was. The metal clips were removed, and the glass plate was immersed in a 1 L poly beaker filled with ion-exchanged water, and the beaker was immersed in an ultrasonic cleaner and ultrasonic-treated at room temperature for 10 minutes. As a result, the glass plate came off, and a swollen sheet-like crosslinked product was obtained. That is, by using LiSS and BVBSI-Li with reduced bound bromine, electrolyte membranes and coating films with suppressed bromine liberation over time can be easily formed.

[0145]

Table 4

[0146] Comparative Example 8 Production of Sodium 4-Styrenesulfonate (NaSS) (4) <Production of NaSS> Except for using the 69.7 wt%-BEBS aqueous solution obtained in Comparative Example 5, the same operations as in Example 12 were carried out to obtain 311.60 g of a wet cake of NaSS.

[0147] <Purification of NaSS> Except for using the wet cake of NaSS obtained above, the same operations as in Example 12 were carried out to obtain 273.70 g of a wet cake of purified NaSS. The purified NaSS was subjected to ion exchange treatment in the same manner as in Example 12 to obtain 32.80 g of dry crystals of high-purity NaSS. The purity was 99.3 wt% and the moisture was 0.7 wt%. The organic impurities such as isomers analyzed by high performance liquid chromatography (HPLC) were (a) sodium orthostyrenesulfonate 0.00%, (b) sodium 4-(2-bromoethyl)benzenesulfonate 0.00%, (c) sodium metastyrenesulfonate 0.32%, (d) sodium bromostyrenesulfonate 0.01%, (e) sodium 4-(2-hydroxyethyl)benzenesulfonate 0.00% (however, it is the area ratio when the total of the HPLC peak areas of the above organic impurities and NaSS is taken as 100). That is, the content of sodium bromostyrenesulfonate in the high-purity NaSS was the same as in Example 12. However, as a result of quantifying the total bromine content, that is, the bound bromine by combustion decomposition ion chromatography, it was 413 ppm, which was much higher than in Examples 12 to 14 (Table 5). It is considered that this is because BEBS with a high content of nuclear brominated BEBS was used as the raw material. Hereinafter, in the same manner as in the examples, high-purity NaSS was polymerized to be induced to PSS, and the change in bromine ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0148] <Production of poly-NaSS> The high-purity NaSS obtained above was polymerized under the same conditions as in Example 12 to obtain an aqueous solution of poly-NaSS having a number average molecular weight Mn of 112,000 and a weight average molecular weight Mw of 285,000.

[0149] <Preparation and stability confirmation of PSS>[ The aqueous poly-NaSS solution obtained above was purified under the same conditions as in Example 12 to obtain 235.97 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 112,000, the weight average molecular weight was 285,000 (Mw / Mn = 2.54), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. The PSS aqueous solution obtained above was aged, and the change in bromide ion concentration was traced. As shown in Table 5, it was revealed that the increase in bromide ions over time was remarkable compared to Examples 12 to 14. This is presumably because there is a large amount of bound bromine in NaSS, that is, there are many nuclear brominated compounds contained in BEBS, which is the precursor.

[0150] Comparative Example 9 Synthesis of Sodium 4-Styrenesulfonate (5) <Synthesis of NaSS> Using the 72.1 wt%-BEBS aqueous solution obtained in Comparative Example 1 as a raw material, 325.46 g of wet crystals of NaSS were obtained under the same conditions as in Example 12 in all other respects.

[0151] <Purification of NaSS> The NaSS obtained above was subjected to ion exchange treatment under the same conditions as in Example 12 to obtain 32.50 g of high-purity NaSS crystals. The purity after drying was 99.5 wt%, the moisture was 0.5 wt%, the bromide ion was less than 1 ppm, and the total bromine content was 665 ppm. It is clear that the total bromine amount is larger compared to Examples 12 to 14 (Table 5). This is presumably because BEBS with a large content of nuclear brominated BEBS was used as a raw material. Similar to Example 12, high-purity NaSS was polymerized to be induced into PSS, and the change in bromide ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0152] <Synthesis of Poly-NaSS> Using the high-purity NaSS obtained above, an aqueous poly-NaSS solution was obtained under the same conditions as in Example 12 in all other respects. The number average molecular weight Mn was 113,000, and the weight average molecular weight Mw was 291,000 (Mw / Mn = 2.56).

[0153] <Preparation and Stability Confirmation of PSS> Except for using the aqueous poly-NaSS solution obtained above, ultrafiltration and ion exchange treatment were carried out under the same conditions as in Example 12 to obtain 238.48 g of a 10.0 wt% PSS aqueous solution. The number average molecular weight was 113,000, the weight average molecular weight was 291,000, the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. The PSS aqueous solution obtained above was aged, and the change in bromide ion concentration was traced. As a result, as shown in Table 5, it was clear that the increase in bromide ions over time was remarkable compared to Examples 12 to 14. This is considered to be because the amount of bound bromine in NaSS is large, that is, because the amount of nuclear brominated compounds contained in BEBS, which is the precursor, is large.

[0154] Comparative Example 10 Synthesis of Sodium 4-Styrenesulfonate (6) <Synthesis of NaSS> Except for using the 70.8 wt%-BEBS aqueous solution obtained in Comparative Example 2 as a raw material, 315.02 g of wet crystals of NaSS were obtained under the same conditions as in Example 12.

[0155] <Purification of NaSS> The NaSS obtained above was subjected to ion exchange treatment under the same conditions as in Example 12 to obtain 32.00 g of high-purity NaSS crystals. The purity after drying was 99.5 wt%, the moisture was 0.5 wt%, the bromide ion was less than 1 ppm, and the total bromine content was 1264 ppm. It was clear that the total bromine amount was large compared to Examples 12 to 14 (Table 5). This is considered to be because BEBS with a large content of nuclear brominated BEBS was used as a raw material. Similar to Example 12, NaSS was polymerized to be induced into PSS, and the change in bromide ion concentration (the presence of unstable bound bromine) over time was confirmed. <OOO1014> <Synthesis of Poly-NaSS> Except for using the high-purity NaSS obtained above, an aqueous poly-NaSS solution was obtained under the same conditions as in Example 12. The number average molecular weight Mn was 112,000, and the weight average molecular weight Mw was 283,000 (Mw / Mn = 2.53).

[0157] <Preparation and Stability Confirmation of PSS> Except for using the aqueous poly-NaSS solution obtained above, ultrafiltration and ion exchange treatment were performed under the same conditions as in Example 12 to obtain 238.48 g of a 10.0 wt% PSS aqueous solution. The number average molecular weight was 112,000, the weight average molecular weight was 283,000 (Mw / Mn = 2.53), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the PSS aqueous solution was aged, and the change in bromide ion concentration was traced. As shown in Table 5, it was clear that the increase in bromide ions over time was significant compared to Examples 12 to 14. This is presumably because the amount of bound bromine in NaSS is large, that is, because the amount of nuclear brominated compounds contained in BEBS, the precursor, is large.

[0158] Comparative Example 11 Synthesis of Sodium 4-Styrenesulfonate (7) <Synthesis of NaSS> Except for using the 72.3 wt% -BEBS aqueous solution obtained in Comparative Example 4 as a raw material, 327.31 g of wet crystals of NaSS were obtained under the same conditions as in Example 12.

[0159] <Purification of NaSS> The NaSS obtained above was subjected to ion exchange treatment under the same conditions as in Example 12 to obtain 31.60 g of high-purity NaSS crystals. The purity after drying was 99.4 wt%, the moisture was 0.6 wt%, the bromide ion was less than 1 ppm, and the total bromine content was 4463 ppm. It was clear that the total bromine amount was large compared to Examples 12 to 14. This is presumably because BEBS containing a large amount of nuclear brominated BEBS was used as a raw material. Similar to Example 12, NaSS was polymerized to be induced into PSS, and the change in bromide ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0160] <Synthesis of Poly-NaSS> Except for using the high-purity NaSS obtained above, an aqueous poly-NaSS solution was obtained under the same conditions as in Example 12. The number average molecular weight Mn was 113,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.52).

[0161] <Preparation and Stability Confirmation of PSS> Except for using the aqueous poly-NaSS solution obtained above, ultrafiltration and ion exchange treatment were carried out under the same conditions as in Example 12 to obtain 244.69 g of a 10.0 wt% PSS aqueous solution. The number average molecular weight was 113,000, the weight average molecular weight was 285,000 (Mw / Mn = 2.52), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above PSS aqueous solution was aged, and the change in bromide ion concentration was traced. As shown in Table 5, it was clear that the increase in bromide ions over time was significant compared to Examples 12 to 14. This is considered to be due to the large amount of bound bromine in NaSS, that is, the large amount of nuclear brominated compounds contained in BEBS, which is the precursor.

[0162] Comparative Example 12 Synthesis of Ethyl 4-Styrenesulfonate (4) <Synthesis of Ethyl 4-Styrenesulfonate> Except for using the high-purity NaSS obtained in Comparative Example 9 as a raw material, 11.80 g of ETSS was obtained by the same operation as in Example 15. The purity based on area% determined by gas chromatography was 93.0%. The bromine content in the ETSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 651 ppm, which was clearly higher in bromine content compared to Examples 15 to 17 (Table 5). This is considered to be due to using NaSS derived from BEBS with a large content of nuclear brominated BEBS as a raw material. Furthermore, by the following method, ETSS was polymerized to be induced into PSS, and the change in bromide ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0163] <Synthesis of Poly-ETSS> Except for using the ETSS obtained above as a raw material, ETSS was polymerized under the same conditions as in Example 15 to obtain poly-ETSS.

[0164] <Preparation and Stability Confirmation of PSS> Using the poly-ETSS obtained above as a raw material, 26.88 g of a 10.0 wt% PSS aqueous solution was obtained under the same conditions as in Example 15. The number average molecular weight was 9,000, the weight average molecular weight was 12,000 (Mw / Mn = 1.33), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above PSS aqueous solution was aged and the change in bromine ion concentration was traced. As shown in Table 5, it was revealed that the increase in bromine ions over time was remarkable compared to Examples 15 to 17. This is presumably because the amount of bound bromine in ETSS is large, that is, because the amount of nuclear brominated compounds contained in BEBS, which is the precursor, is large.

[0165] Comparative Example 13 Synthesis of Ethyl 4-Styrenesulfonate (5) <Synthesis of ETSS> Using the high-purity NaSS obtained in Comparative Example 10 as a raw material, 11.90 g of ETSS was obtained under the same conditions as in Example 15. The purity based on area% determined by gas chromatography was 93.0%. The bromine content in the ETSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 1331 ppm, revealing that the bromine content was higher compared to Examples 15 to 17 (Table 5). This is presumably because NaSS derived from BEBS with a high content of nuclear brominated BEBS was used as a raw material. Furthermore, by the following method, ETSS was polymerized to induce PSS, and the change in bromine ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0166] <Synthesis of poly-ETSS> Using the ETSS obtained above as a raw material, ETSS was polymerized under the same conditions as in Example 15 to obtain poly-ETSS.

[0167] <Preparation and Stability Confirmation of PSS> Using the poly-ETSS obtained above as a raw material, 26.99 g of a 10.0 wt% PSS aqueous solution was obtained by the same operation as in Example 15. The number average molecular weight was 9,000, the weight average molecular weight was 12,000 (Mw / Mn = 1.33), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above PSS aqueous solution was aged and the change in bromine ion concentration was traced. As shown in Table 5, it was revealed that the increase in bromine ions over time was remarkable compared to Examples 15 to 17. This is presumably because the amount of bound bromine in ETSS is large, that is, the amount of nuclear brominated compounds contained in BEBS, which is the precursor, is large.

[0168] Comparative Example 14 Synthesis of Ethyl 4-Styrenesulfonate (6) <Synthesis of ETSS> Using the high-purity NaSS obtained in Comparative Example 11 as a raw material, 11.95 g of ETSS was obtained under the same conditions as in Example 15. The purity based on area% determined by gas chromatography was 94.0%. The bromine content in the ETSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 4667 ppm, which was clearly higher in bromine content compared to Examples 15 to 17 (Table 5). This is presumably because NaSS derived from BEBS with a high content of nuclear brominated BEBS was used as a raw material. Furthermore, by the following method, ETSS was polymerized to be induced into PSS, and the change in bromine ion concentration (the presence of unstable bound bromine) over time was confirmed.

[0169] <Synthesis of poly-ETSS> [[ID=第十八条]]Using the ETSS obtained above as a raw material, ETSS was polymerized under the same conditions as in Example 15 to obtain poly-ETSS.

[0170] <Preparation and Stability Confirmation of PSS> Using the poly-ETSS obtained above as a raw material, 26.10 g of a 10.0 wt% PSS aqueous solution was obtained by the same operations as in Example 15. The number average molecular weight was 9,000, the weight average molecular weight was 11,000 (Mw / Mn = 1.22), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. As a result of aging the above PSS aqueous solution and tracking the bromine ion concentration, as shown in Table 5, it is clear that the increase in bromine ions over time is remarkable compared to Examples 15 to 17. This is presumably because the amount of bound bromine in ETSS is large, that is, because the amount of nuclear brominated compounds contained in BEBS, the precursor, is large.

[0171] Comparative Example 15 Synthesis of neopentyl 4-styrenesulfonate (2) <Synthesis of NPSS> A ClSS solution was prepared under the same conditions as in Example 15, such as the charged weight, except that high purity NaSS obtained in Comparative Example 9 was used as a raw material, and 35.10 g of white crystals of NPSS were obtained under the same conditions as in Example 18. The yield based on ClSS was 24%, 1 The purity determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 97.3%. The bromine content in the NPSS determined by ion chromatography, that is, the inorganic bromine content extracted with pure water, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 649 ppm, which is clearly higher in bromine content than in Example 18 (Table 5). This is presumably because NaSS derived from BEBS with a high content of nuclear brominated BEBS was used as a raw material. Similar to Example 18, NPSS was polymerized to derive PSS, and the change in bromine ion concentration over time (the presence of unstable bound bromine) was confirmed.

[0172] <H <Synthesis of poly-NPSS> Using the NPSS obtained above as a raw material, 6.99 g of poly-NPSS (yield based on NPSS was 71%) was obtained by the same operations as in Example 18.

[0173] <Preparation and stability confirmation of PSS> Using the poly-NPSS obtained above as a raw material, the same operations as in Example 18 were performed in all other respects to obtain 57.32 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 9,000, the weight average molecular weight was 11,000 (Mw / Mn = 1.22), the bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above PSS aqueous solution was aged and the bromine ion concentration was tracked. As a result, as shown in Table 5, it was clear that the increase in bromine ions over time was remarkable compared to Example 18. This is presumably because the amount of bound bromine in NPSS is large, that is, because there are many nuclear brominated compounds that may be contained in the precursor BEBS.

[0174] Comparative Example 16 Production of Sodium 4-Styrenesulfonyl(trifluoromethylsulfonylimide) (TfNS-Na) (2) <Synthesis of TfNS-Na> Using the high-purity NaSS obtained in Comparative Example 9 as a raw material, 24.65 g of TfNS-Na was obtained (yield 73%) by the same operations as in Example 19 in all other respects.

[0175] <Purification of TfNS-Na> The TfNS-Na obtained above was ion-exchanged by the same operation as in Example 19 and neutralized with sodium hydroxide to obtain 20.60 g of crystals of high-purity TfNS-Na. 1 The purity after drying determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 98.3 wt%, the water content was 1.5 wt%, the bromine ion concentration determined by ion chromatography was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 642 ppm. It was clear that the amount of bound bromine was large compared to Example 19 (Table 5). This is presumably because NaSS derived from BEBS with a high content of nuclear brominated BEBS was used as a raw material. Similar to Example 19, TfNS-Na was induced to poly-TfNS-H, and the change in bromine ion concentration over time (the presence of unstable bound bromine) was confirmed. Similar to Example 12, the above PSS aqueous solution was aged and the bromine ion concentration was tracked. As a result, as shown in Table 5, it was clear that the increase in bromine ions over time was remarkable compared to Example 18. This is presumably because the amount of bound bromine in NPSS is large, that is, because there are many nuclear brominated compounds that may be contained in the precursor BEBS.

[0176] <Preparation and Stability Confirmation of Poly-TfNS-H> Except for using the TfNS-Na obtained above, poly-TfNS-Na was synthesized under the same conditions as in Example 19. The polymerization conversion rate was 98.7%, the number average molecular weight was 35,000, and the weight average molecular weight was 82,000 (Mw / Mn = 2.34). Subsequently, by performing ultrafiltration and ion exchange treatment under the same conditions as in Example 19, 149.79 g of a 10 wt% aqueous solution of poly-TfNS-H was obtained. The bromine ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, the above poly-TfNS aqueous solution was aged, and the bromine ion concentration was traced. As a result, as shown in Table 5, it is clear that the increase in bromine ions over time is remarkable compared to Example 19. This is presumably because the amount of bound bromine in TfNS-Na is large, that is, because there are many nuclear brominated compounds that may be contained in BEBS, which is the precursor.

[0177] Comparative Example 17 Production of Lithium 4-Styrenesulfonate (2) <Synthesis of LiSS> Except for using the 72.3 wt%-BEBS aqueous solution of Comparative Example 4 as a raw material, 203.50 g of a wet cake of LiSS was obtained under the same conditions as in Example 20.

[0178] <Purification of LiSS> The above LiSS was purified under the same conditions as in Example 20 to obtain 73.50 g of dry LiSS. The purity was 98.6 wt%, the moisture was 1.40 wt%, the bromine ions were less than 1 ppm, and the total bromine content was 4339 ppm. It is clear that the total bromine amount is larger compared to Example 20 (Table 5). This is presumably because there were many nuclear brominated BEBS in the BEBS used as the raw material. Similar to Example 20, LiSS was polymerized to be induced to PSS, and an increase in the bromine ion concentration over time (the presence of unstable bound bromine) was confirmed.

[0179] <Synthesis of Poly-LiSS> Except for using the LiSS obtained above, polymerization was carried out under the same conditions as in Example 20. The polymerization conversion rate was 99.7%, the number average molecular weight was 39,000, and the weight average molecular weight was 91,000 (Mw / Mn = 2.33).

[0180] <Preparation of PSS and Confirmation of Stability> The obtained aqueous poly-LiSS solution was subjected to ultrafiltration and ion exchange treatment under the same conditions as in Example 20 to obtain 242.56 g of a 10.0 wt% PSS aqueous solution. The bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 20, the obtained PSS aqueous solution was aged, and the bromide ion concentration was traced. As shown in Table 5, it is clear that the increase in bromide ions over time is larger compared to Example 20. This is considered to be due to the large amount of bound bromine in LiSS, that is, the large amount of nuclear brominated substances that may be contained in the precursor BEBS.

[0181] Comparative Example 18 Production of Lithium Bis-(4-styrenesulfonyl)imide (BVBSI-Li) <Synthesis of 4-Vinylbenzenesulfonamide> Using the ClSS solution synthesized in Comparative Example 14 as a raw material, 6.10 g (yield 66%) of a white solid of 4-styrenesulfonamide was obtained under the same conditions as in Example 23 for all charging weights and the like.

[0182] <Synthesis of BVBSI-Li> Using the 4-styrenesulfonamide obtained above and the ClSS solution synthesized in Comparative Example 14, 6.25 g of white crystals of BVBSI-Li were obtained under the same conditions as in Example 23 for all charging weights and the like. The yield based on ClSS was 60%. 1 The purity determined by 1H-NMR (internal standard substance 1,3,5-trimethylbenzene) was 93.3%. The bromine content in the high-purity BVBSI-Li determined by ion chromatography, that is, the inorganic bromine content analyzed in an aqueous solution, was less than 1 ppm, and the total bromine content determined by combustion decomposition ion chromatography was 4556 ppm.

[0183] Example 24 Production of Polystyrenesulfonic Acid (PSS) (1)   <Synthesis of Poly-NaSS> In Example 12, after polymerizing high-purity NaSS, instead of adding 1.64 g of a 48 wt% sodium hydroxide aqueous solution and heating at 60 °C for 24 hours under a nitrogen stream, 1.65 g of a 48 wt% sodium hydroxide aqueous solution and 1.86 g of sodium hypophosphite monohydrate were added, and stirring was continued at 110 °C for 15 hours while maintaining the solution pH ≥ 13 or higher to obtain an aqueous poly-NaSS solution. The number average molecular weight Mn of poly-NaSS was 114,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.50).

[0184] <Preparation and Stability Confirmation of PSS> The above aqueous poly-NaSS solution was purified by the same operation as in Example 12 to obtain 230.05 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight was 114,000, the weight average molecular weight was 282,000 (Mw / Mn = 2.47), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. Similar to Example 12, PSS solid was obtained and analyzed for halogen content. As a result, the total bromine content was 63 ppm, which was decreased compared to Example 12. It is considered that a part of the bound bromine was liberated by appropriate chemical treatment before purifying poly-NaSS. In addition, the total chlorine content in the PSS solid was less than 1 ppm. Similar to Example 12, the above 10 wt% PSS aqueous solution was aged at 70 °C, and the change in bromide ion concentration was traced. As a result, as shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 12.

[0185] Example 25 Production of Polystyrene Sulfonic Acid (PSS) (2) <Synthesis of Poly-NaSS> In Example 13, after polymerizing high-purity NaSS, instead of adding 1.64 g of a 48 wt% sodium hydroxide aqueous solution and heating at 60 °C for 24 hours under a nitrogen stream, 1.65 g of a 48 wt% sodium hydroxide aqueous solution was added, and stirring was continued at 110 °C for 20 hours while maintaining the solution pH ≥ 13 to obtain an aqueous poly-NaSS solution. The number average molecular weight Mn of poly NaSS was 114,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.50).

[0186] <Preparation and Stability Confirmation of PSS> The aqueous poly NaSS solution obtained above was purified by the same operation as in Example 13 to obtain 231.30 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight of PSS was 112,000, the weight average molecular weight was 281,000 (Mw / Mn = 2.51), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. PSS solid was obtained in the same manner as in Example 12, and as a result of analyzing the total bromine content, it was 35 ppm, which was lower than that in Example 13. It is considered that a part of the bound bromine was released by appropriate chemical treatment before purifying poly NaSS. In addition, the total chlorine content in the PSS solid was less than 1 ppm. Similar to Example 13, the above 10 wt% PSS aqueous solution was aged at 70 °C, and the change in bromide ion concentration was traced. As shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 13.

[0187] Example 26 Production of Polystyrene Sulfonic Acid (PSS) (3) <Synthesis of Poly NaSS> In Example 14, after polymerizing high-purity NaSS, instead of adding 1.64 g of a 48 wt% sodium hydroxide aqueous solution and heating at 60 °C for 24 hours under a nitrogen stream, 2.01 g of a 48 wt% sodium hydroxide aqueous solution and 1.90 g of sodium hypophosphite monohydrate were added, and stirring was continued at 110 °C for 15 hours while maintaining the solution pH ≥ 13 to obtain an aqueous poly NaSS solution. The number average molecular weight Mn of poly NaSS was 114,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.50).

[0188] <Preparation and Stability Confirmation of PSS> The aqueous poly-NaSS solution obtained above was purified by the same operation as in Example 14 to obtain 232.02 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight of PSS was 113,000, the weight average molecular weight was 282,000 (Mw / Mn = 2.50), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. PSS solid was obtained in the same manner as in Example 12, and the total bromine content was analyzed. As a result, it was 91 ppm, which was lower than that in Example 14. It is considered that a part of the bound bromine was liberated by appropriate chemical treatment before purifying the poly-NaSS. The total chlorine content was less than 1 ppm. Similar to Example 14, the above 10 wt% PSS aqueous solution was aged at 70 °C, and the change in bromide ion concentration was traced. As a result, as shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 14. It is considered that a part of the bound bromine was liberated by appropriate chemical treatment before purifying the poly-NaSS.

[0189] Example 27 Production of styrenesulfonic acid / styrene (SS / St) copolymer <Synthesis of NaSS / styrene copolymer> In Example 21, 1.65 g of a 48 wt% sodium hydroxide aqueous solution was added to a 15 wt% NaSS / styrene copolymer aqueous solution before purification under a nitrogen stream, and the mixture was stirred at 90 °C for 24 hours while maintaining the solution pH ≧ 13 to obtain a NaSS / styrene copolymer aqueous solution. The number average molecular weight Mn of the copolymer was 33,000, and the weight average molecular weight Mw was 74,000 (Mw / Mn = 2.24).

[0190] <Preparation and stability confirmation of PSS> The NaSS / styrene copolymer obtained above was purified by the same operation as in Example 2_{1} to obtain 229.50 g of a 10.00 wt% styrenesulfonic acid / styrene copolymer aqueous solution. The number average molecular weight Mn of the acid-type copolymer was 33,000, the weight average molecular weight Mw was 74,000 (Mw / Mn = 2.24), the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. The 10 wt% copolymer aqueous solution was aged at 70 °C, and the change in bromide ion concentration was traced. As shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 21. It is considered that a part of the bound bromine was released by appropriate chemical treatment before purifying the polymer.

[0191] Example 28 Production of styrenesulfonic acid / methacrylic acid (SS / MAA) copolymer <Synthesis of NaSS / methacrylic acid copolymer> In Example 22, 5.00 g of a 48 wt% sodium hydroxide aqueous solution was added to a 15 wt% NaSS / MAA copolymer aqueous solution before purification under a nitrogen stream, and stirring was continued at 90 °C for 24 hours while maintaining the solution at pH ≥ 13 to obtain a NaSS / methacrylic acid copolymer. The number average molecular weight was 46,000, and the weight average molecular weight was 129,000 (Mw / Mn = 2.80).

[0192] <Synthesis and stability confirmation of styrenesulfonic acid / methacrylic acid copolymer> The above-mentioned NaSS / methacrylic acid copolymer was subjected to ultrafiltration and ion exchange treatment under the same conditions as in Example 22 to obtain 258.06 g of a 10.0 wt% aqueous solution of styrenesulfonic acid / methacrylic acid copolymer. The bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. The solid of the styrenesulfonic acid / methacrylic acid copolymer was obtained in the same manner as in Example 12, and the total bromine content was analyzed. As a result, it was 45 ppm, and the total chlorine content was less than 1 ppm. [[ID=十六]]

[0193] [[ID=十七]] <Stability of styrenesulfonic acid / methacrylic acid copolymer> Similar to Example 22, the 10 wt% styrenesulfonic acid / methacrylic acid copolymer aqueous solution was aged at 70 °C, and the change in bromide ion concentration was traced. As shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 22. It is considered that a part of the bound bromine was released by appropriate chemical treatment before purifying the polymer.

[0194] Example 29 Production of Polystyrene Sulfonic Acid (PSS) (4) <Synthesis of Poly NaSS> In Example 12, after polymerizing high-purity NaSS, instead of adding 1.64 g of a 48 wt% aqueous sodium hydroxide solution and heating at 60°C for 24 hours under a nitrogen stream, 0.50 g of sodium formate and 0.05 g of palladium carbon (Pd content 5 wt%) were added, and stirring was continued at 90°C for 24 hours as it was. Then, the polymer solution was filtered through a membrane filter with a pore size of 0.45 μm to remove palladium carbon. The number average molecular weight Mn of poly NaSS was 114,000, and the weight average molecular weight Mw was 285,000 (Mw / Mn = 2.50).

[0195] <Preparation of PSS and Confirmation of Stability> The aqueous poly NaSS solution obtained above was purified by the same operation as in Example 12 to obtain 230.36 g of a 10.00 wt% PSS aqueous solution. The number average molecular weight of PSS was 114,000, the weight average molecular weight was 282,000, the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. A solid of the copolymer was obtained in the same manner as in Example 12, and as a result of analyzing the total bromine content, it was 51 ppm, and the total chlorine content was less than 1 ppm. Similar to Example 12, the above 10 wt% PSS aqueous solution was aged at 70°C, and as a result of tracking the change in the bromide ion concentration, as shown in Table 5, it is clear that the increase in bromide ions over time is further suppressed compared to Example 14. It is considered that this is because a part of the bound bromine was released by the chemical treatment of poly NaSS.

[0196] Comparative Example 19 Production of Polystyrene Sulfonic Acid (5) <Synthesis of Poly NaSS> In Comparative Example 11, after polymerizing high-purity NaSS, instead of adding 1.64 g of a 48 wt% aqueous sodium hydroxide solution and heating at 60°C for 24 hours under a nitrogen stream, 2.02 g of a 48 wt% aqueous sodium hydroxide solution was added and stirred at 110°C for 15 hours while maintaining the solution pH ≥ 13 to obtain an aqueous poly-NaSS solution. The number-average molecular weight Mn was 113,000, and the weight-average molecular weight Mw was 285,000 (Mw / Mn = 2.52).

[0197] <Preparation and Stability Confirmation of PSS> Except for using the aqueous poly-NaSS solution obtained above, ultrafiltration and ion exchange treatment were performed under the same conditions as in Comparative Example 11 to obtain 240.61 g of a 10.0 wt% PSS aqueous solution. The number-average molecular weight was 113,000, the weight-average molecular weight was 283,000, the bromide ion concentration was less than 1 ppm, and the sodium content was less than 1 ppm. PSS solid was obtained in the same manner as in Example 12, and as a result of analyzing the total bromine content, it was 2721 ppm, and the total chlorine content was less than 1 ppm. Similar to Comparative Example 11, the above 10 wt% PSS aqueous solution was aged, and the change in the bromide ion concentration was tracked. As shown in Table 5, the increase in bromide ions over time was halved compared to Comparative Example 11, but it was clearly significantly larger compared to Examples 12 to 14 and Example 25. Although poly-NaSS was chemically treated under appropriate conditions, it is considered that the amount of bound bromine in NaSS was too large, that is, the amount of nuclear brominated compounds contained in BEBS, the precursor, was too large.

[0198]

Table 5

[0199] Example 30 Production of Polystyrene Sulfonic Acid Composition (1) Hydroquinone (700 ppm relative to polymer content) was added to the 10 wt% styrene sulfonic acid / styrene copolymer aqueous solution obtained in Example 27, and the solution was divided into sample bottles, sealed, and aged in an oven at 70°C. Changes in molecular weight and bromide ion concentration were tracked. As shown in Table 6, the increase in bromide ions was small, and the decrease in molecular weight was significantly suppressed compared to Comparative Example 20.

[0200] Example 31: Preparation of polystyrene sulfonic acid composition (2) 4-methoxyphenol (1500 ppm relative to polymer content) was added to the 10 wt% styrene sulfonic acid / styrene copolymer aqueous solution obtained in Example 27, and the changes in weight-average molecular weight and bromide ion concentration were tracked in the same manner as in Example 30. As shown in Table 6, the increase in bromide ions was small, and it was clear that the decrease in molecular weight was significantly suppressed compared to Comparative Example 20.

[0201] Comparative Example 20: Production of a polystyrene sulfonic acid composition (3) 4-methoxyphenol (10 ppm relative to polymer content) was added to the 10 wt% styrene sulfonic acid / styrene copolymer aqueous solution obtained in Example 27, and the changes in weight-average molecular weight and bromide ion concentration were tracked, similar to Example 30. As shown in Table 6, although the increase in bromide ions was small, it is clear that the decrease in molecular weight was significant compared to Examples 30 and 31.

[0202] [Table 6] [Industrial applicability]

[0203] The 4-(2-bromoethyl)benzenesulfonic acid with reduced nuclear bromine content according to the present invention is useful as a precursor for producing styrenesulfonic acids and their polymers with reduced bound bromine content. These styrenesulfonic acids and their polymers with reduced bound bromine content are extremely useful, especially in electrical materials applications, such as modifiers for secondary batteries, dopants for conductive polymers, additives for semiconductor polishing and cleaning agents, photoresists, and organic EL elements. [Explanation of Symbols]

[0204] A: Peak of 4-(2-hydroxyethyl)benzenesulfonic acid B: Peak of the para-form of B:BEBS C:BEBS orthomorphic peak D: Peak of 4-(1-bromoethyl)benzenesulfonic acid E: 2-Bromo-4-(2-bromoethyl)benzenesulfonic acid (nuclear brominated BEBS) peak a: Peak position of sodium orthostyrene sulfonate b: Peak position of sodium 4-(2-bromoethyl)benzenesulfonate c: Peak position of sodium metastyrene sulfonate d: Peak position of sodium bromostyrene sulfonate e: Peak position derived from sodium 4-(2-hydroxyethyl)benzenesulfonate

Claims

[Claim 1] High-purity 4-(2-bromoethyl)benzenesulfonic acid in which the amount of nuclear brominated 2-bromoethylbenzenesulfonic acid, represented by the following general formula (A), is 0.10% or less relative to 4-(2-bromoethyl)benzenesulfonic acid [however, this is the peak area percentage determined by liquid chromatography (LC), and is the peak area percentage of nuclear brominated 2-bromoethylbenzenesulfonic acid when the peak area of ​​4-(2-bromoethyl)benzenesulfonic acid is set to 100%]. [Chem.17]

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