JPH08193104A - Integrated production of water-soluble sulfonated polymer - Google Patents

Abstract

PURPOSE: To produce a high-quality water-soluble sulfonated polymer through an integrated process by polymerizing a monomer in a solvent, subsequently sulfonating the resulting polymer dissolved in the solvent, and recovering the solvent. CONSTITUTION: The process comprises the steps of: (A) polymerizing a monomer in a halogenohydrocarbon solvent to obtain a solution of the resulting polymer, the solid(s) other than the polymer being optionally removed; (B) contacting the polymer solution with a sulfonating agent to sulfonate the polymer; (C) adding water to the solution of the sulfonated polymer and allowing the mixture to stand, either after neutralization of the solution or without neutralization, to separate the aqueous phase containing the sulfonated polymer or a salt thereof from the halogenohydrocarbon solvent phase; (D) adjusting the pH of the solvent phase to 4 to 10, before the solvent is recovered by distillation; and (E) feeding the recovered solvent to the step (A) for reuse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for consistently producing a water-soluble sulfonated polymer such as polystyrene sulfonic acid or a salt thereof from polymerization to sulfonation.

[0002]

2. Description of the Related Art There are many known methods for polymerizing polymers and sulfonation of polymerized polymers. For example, as a method of polymerizing the polymer, a method of polymerizing the polymer in a solvent (Japanese Patent Laid-Open Nos. 48-54189 and 53-53).
-24382, 54-38392, 56-15
No. 2814) or a method of thermal polymerization without solvent (Japanese Patent Publication No.
9-2340, 49-2341, JP-A-48-1
2887, 49-22494, 54-1799.
No. 2 etc.) and the like, and the polymer produced in each case is taken out in a bulk state. Further, as a method of sulfonation of such a polymer, usually, a method of dissolving the polymer in a solvent, sulfonation it with a predetermined sulfonating agent, and then using the recovered solvent as a sulfonation solvent is adopted. (Japanese Patent Laid-Open Nos. 48-12895 and 50-11)
No. 2481, No. 58-11506, and JP-A-2-294.
No. 305). Therefore, in the conventional method, the production of the polymer and the sulfonation of the polymer are performed separately, which makes it impossible to produce the polymer efficiently, which is economically disadvantageous.

On the other hand, a method for directly producing a sulfonated styrene oligomer from a monomer such as styrene is also known (Japanese Patent Laid-Open Nos. 48-12895 and 48-49745). However, in this method, a monomer such as styrene is charged in a solvent, and sulfonation and polymerization proceed simultaneously,
There is a problem that only an oligomer having a weight average molecular weight of 1200 to 5000 can be obtained. Further, if it is attempted to carry out the production of the polymer and the sulfonation with the same solvent, for example, toluene is suitable for the polymerization of polystyrene (JP-A-53-53).
No. 24382) is not suitable as a sulfonation solvent because the solvent itself is sulfonated. Under such circumstances, there has not yet been reported a process of carrying out sulfonation from the production of a polymer with the same solvent and using the recovered solvent again for the production of the polymer.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a polymer in a solvent after the polymerizable monomer is polymerized in a solvent, and the polymer is continuously dissolved in the solvent without being taken out from the solvent as a bulk. It is an object of the present invention to provide a method capable of carrying out sulfonation of the above-mentioned compound, recovering the solvent thereof, and producing a water-soluble sulfonated polymer having excellent quality from polymerization to sulfonation consistently.

[0005]

The present invention is directed to the production of a polymer by the polymerization of monomers, the sulfonation of the polymer, the separation of the sulfonated polymer and the separation of the solvent and solvent in a specific manner, and the separated solvent. It was made based on the finding that the above problem can be effectively solved by distilling under a specific condition to obtain and then reusing it in the step of polymerizing a monomer. That is, the present invention, (A) a polymerizable monomer, after polymerizing in a halogenated hydrocarbon solvent to produce a polymer, the step of removing the solid content or obtaining a solution of the polymer without removal, ( B) a step of contacting a sulfonating agent with the obtained polymer solution to sulfonate the polymer in the solution, (C) neutralizing the obtained sulfonated polymer solution, or adding water without neutralizing Standing still, transferring the sulfonated polymer or its salt to the aqueous phase, separating the aqueous phase and the halogenated hydrocarbon solvent phase, after adjusting the pH of the separated solvent phase to 4 ~ 10, distillation To recover the halogenated hydrocarbon solvent, and (E) supply the recovered solvent to the step (A) and reuse it, which is an integrated method for producing a water-soluble sulfonated polymer. I will provide a.

In the present invention, first, in step (A), a polymerizable monomer is polymerized in a halogenated hydrocarbon solvent to produce a polymer. Here, examples of the polymerizable monomer include aromatic vinyl monomers having 8 to 12 carbon atoms, preferably 8 to 10 carbon atoms, such as styrene, α-methylstyrene, p-hydroxystyrene, and vinyltoluene, or a combination thereof. To be Also, combinations of these aromatic vinyl monomers with isoprene, butadiene, acrylic acid derivatives and the like can be mentioned.

As the halogenated hydrocarbon solvent, 1,2-
Examples thereof include dichloroethanes such as dichloroethane, chloroform, carbon tetrachloride, dichloromethane, tetrachloroethane, tetrachloroethylene, and the like, or a mixture of two or more thereof. Of these, dichloroethanes are preferred. In the present invention, the use ratio of the polymerizable monomer and the halogenated hydrocarbon solvent can be arbitrary,
Weight ratio of polymerizable monomer / halogenated hydrocarbon solvent is 1
/ 99 to 80/20, and more preferably 5
/ 95 to 40/60. Further, the concentration of the polymerizable monomer in the polymerization system may be arbitrary, but preferably 1
It is preferable that the amount is -80% by weight, more preferably 10-60% by weight. The polymerization of the polymerizable monomer in the present invention can be carried out by conventionally known anionic polymerization, cationic polymerization or radical polymerization, but cationic polymerization is preferable. At this time, it is preferable to use a Lewis acid as the catalyst, for example, tin dichloride, tin tetrachloride,
Metal halides such as aluminum chloride and titanium tetrachloride, particularly metal chlorides are preferred. Although the amount of the catalyst used is not limited, it is preferably 0.01 to 1 part by weight per 100 parts by weight of the polymerizable monomer. The catalyst is
It may be added to the weight system in advance, or may be added gradually in accordance with the progress of polymerization. Moreover, when a Lewis acid is used, it is 50 to 100 in the halogenated hydrocarbon solvent.
It is preferred to have 0 ppm, preferably 100-400 ppm, of water present.

In the present invention, a reactor is charged with a halogenated hydrocarbon solvent, a predetermined amount of water and a polymerization catalyst, the temperature is raised to a predetermined temperature, and then a polymerizable monomer is added dropwise to carry out the polymerization. Is preferred. The polymerization temperature is preferably 30 to 150 ° C, preferably 40 to 150 ° C, more preferably 50 to 150 ° C. In the present invention, it is preferable to age the polymerized monomer for about 1 to 5 hours after the polymerization is completed and the polymer is produced. In this way, the final reaction rate is 95% or more, preferably 98% or more. The average molecular weight of the polymer is 2
It is preferable to produce the product having an amount of from 00 to 50000, preferably from 2000 to 30000. In addition to the above conditions, the polymerization of the polymerizable monomer is not limited to those described in JP-A-3-52902, JP-A-3-56509, and JP-A-3-565.
It is also possible to adopt the conditions described in JP-A No. 10 and JP-A No. 53-24382. The contents described in these publications are included in the description of the present specification.

In the present invention, after the polymer is obtained, it is preferable to add an alkaline agent such as calcium hydroxide to change the polymerization catalyst into an insoluble solid content, and then remove it from the system by filtration or the like. For example, 0.1 to 2.0 parts by weight of the alkali agent is added to 100 parts by weight of the polymer, and the mixture may be stirred for about 0.5 to 2.0 hours and then filtered by a conventional method. At this time, it is preferable to use a filter aid such as perlite or celite. In the present invention, the polymer solution thus obtained is contacted with a sulfonating agent in the step (B) to sulfonate the polymer in the solution. The sulfonation is
Usually, it is advisable to introduce the polymer solution taken out from the polymerization reactor into a sulfonation apparatus. The sulfonation of the polymer can be carried out by any method capable of bringing a sulfonating agent into contact with the polymer solution.
174205, JP-A-63-172703, JP-A-4-264107, and JP-A-2-294.
The method described in JP-A No. 305, JP-A No. 3-14803, JP-A No. 3-66706 and the like is preferable. The contents described in these publications are included in the description of the present specification.

Specifically, a polymer solution is introduced into a sulfonation apparatus, a sulfonating agent is added thereto, and the mixture is stirred at a temperature of 10 to 80 ° C. (preferably 25 to 50 ° C.) for 1 hour.
Allow to react for ~ 60 minutes (preferably 1-20 minutes). At this time, with or without addition of a halogenated hydrocarbon solvent to the polymer solution, a solution having a polymer concentration of 5 to 20% by weight was added in a molar ratio of 0.5 to 2.0 mol per a constituent monomer unit of the polymer. An amount of sulfonating agent, preferably 0.7-1.5, is used. Here, as the sulfonating agent, sulfuric anhydride (liquid or gas), sulfuric acid-containing gas, fuming sulfuric acid,
Although chlorosulfonic acid or the like can be used, it is preferable to use sulfuric acid anhydride or a gas containing sulfuric acid anhydride. In carrying out the sulfonation of the present invention, various sulfonation aids such as benzene sulfonic acid and alkylbenzene sulfonic acid can be added. Such sulfonation aids are
JP-A-61-25003, JP-A-50-112
No. 480, Japanese Patent Laid-Open No. 3-59005, and the like.

In the present invention, next, in the step (C),
After neutralizing the obtained sulfonated polymer solution, water is added and allowed to stand, or water is added without neutralization and allowed to stand to transfer the sulfonated polymer or a salt thereof to an aqueous phase, Separate the aqueous phase and the halogenated hydrocarbon solvent phase. Neutralization of the sulfonated polymer solution can be performed with an alkaline agent that can form the desired salt. Examples of the alkaline agent include sodium hydroxide, potassium hydroxide and alkaline earth metal compounds, which are preferably added as an aqueous solution to the sulfonated polymer solution. By neutralization,
A salt of the sulfonated polymer is formed. Neutralization, for example,
JP-A-52-33993, JP-A-63-1894
The method described in JP-A No. 05, JP-A-2-240116 and JP-A-2-296804 can be used. Specifically, it is preferable to add an aqueous solution of sodium hydroxide having a concentration of 5 to 15% and stir for about 1 to 2 hours to neutralize.

Separation of the halogenated hydrocarbon solvent from the sulfonated polymer or its salt is described in JP-A-63-189404, JP-A-2-258802 and Japanese Patent Application No. 5-8.
It can be carried out by the method described in the specification of No. 7218. The contents described in these publications or specifications are included in the description of the present specification. Specifically, water is added to the neutralized sulfonated polymer solution or the non-neutralized sulfonated polymer solution and the mixture is allowed to stand to transfer the sulfonated polymer or its salt to the aqueous phase. Here, it is preferable to add water to the sulfonated polymer solution so that the concentration of the sulfonated polymer or its salt in the aqueous phase after the transfer will be about 10 to 30% by weight. The standing may be performed at any time and temperature as long as the sulfonated polymer or a salt thereof is transferred to the aqueous phase, but is set to 20 to 60 ° C. for 30 minutes to 4 hours, preferably 1 to 2 hours. Is good. When dichloroethane is used as the halogenated hydrocarbon solvent and the sulfonated polymer or salt thereof is sulfonated polystyrene or salt thereof,
Dichloroethane is formed in the lower layer, and an aqueous phase of sulfonated polystyrene or its salt is formed in the upper layer. In the present invention, it is also possible to obtain a salt of sulfonated polystyrene by taking out an aqueous solution phase of sulfonated polystyrene and then adding an alkaline agent such as sodium hydroxide, potassium hydroxide or an alkaline earth metal compound.

In the present invention, in the step (D), an alkaline agent is added to the separated solvent phase to adjust the pH to 4 to 10, preferably 4 to 8.0, and then the halogenated hydrocarbon solvent is distilled off. to recover. Here, examples of the alkaline agent include sodium hydroxide, potassium hydroxide, and alkaline earth metal compounds, and these are preferably used as an aqueous solution. Further, in the present invention, the water content is 10 to 150.
It is preferable to recover ppm halogenated hydrocarbon solvent by distillation such as atmospheric distillation or reduced pressure distillation and / or rectification by a rectification column. When the pH is lower than 4, when recovering the solvent by distillation, some acidic substances such as polymerization catalysts and low sulfonates are mixed in the recovered solvent, and if this is reused for polymerization, a polymer having a certain molecular weight cannot be obtained. The problem arises. On the other hand, when the pH is higher than 10, the decomposition of dichloroethanes is remarkable, which is not preferable. In the present invention, the halogenated hydrocarbon solvent thus recovered can be supplied to the monomer polymerization step of step (A) and used again as the halogenated hydrocarbon solvent. At this time, the water content in the halogenated hydrocarbon solvent to be recovered is set to be smaller than the amount of water present during the polymerization, and water is appropriately added so that the water content in the halogenated hydrocarbon solvent becomes 50 to 1,000 ppm. It is good to add. On the other hand, the aqueous solution of the sulfonated polymer or its salt separated in step (C) is
Alternatively, it can be concentrated into a product by a conventional method. or,
It is also possible to remove the volatile components by flashing or the like to obtain a powder.

[0014]

According to the method of the present invention, after the polymerizable monomer is polymerized in the solvent, the polymer in the solvent is continuously dissolved in the solvent without being taken out from the solvent as a bulk. Since sulfonation is carried out, there is a great industrial advantage that the work efficiency is high. Further, according to the method of the present invention, a halogenated hydrocarbon solvent can be effectively reused and a water-soluble sulfonated polymer having a constant quality and high purity can be produced in a high yield. Next, the present invention will be described with reference to examples.

[0015]

【Example】

Example 1 (A) A five-liter four-necked flask was equipped with a stirrer, a thermometer, a dropping funnel, and a condenser. This reactor was charged with 2 kg of 1,2-dichloroethane (EDC), and 2 g of tin tetrachloride and 0.7 g of pure water as a catalyst.
Was added. While stirring the inside of the reactor, the temperature was raised to the boiling point of EDC, and 2 Kg of styrene was added dropwise using a dropping funnel over 5 hours to carry out polymerization. Furthermore, 4 g of tin tetrachloride was added, and the mixture was further stirred for 2 hours.
After adding DC and further adding 20 g of calcium hydroxide and stirring for 1 hour, the solid content was removed by filtration to obtain a polystyrene solution. (B) 8 kg of EDC was added to this polystyrene solution for dilution. This raw material solution was supplied to a sulfonation reactor together with sulfuric anhydride, and the molar ratio of sulfonating agent to the raw material was 1.
16. The sulfonation reaction was carried out under the conditions of a reaction residence time of 10 minutes and a reaction temperature of 40 ° C.

(C) Further, water was added to the obtained sulfonated product so that the concentration of the sulfonated product in the aqueous phase was 20% by weight to dissolve the sulfonated product, which was transferred to a separatory funnel and allowed to stand for 2 hours. Then, the aqueous phase and the halogenated hydrocarbon solvent phase were separated. (D) Next, the separated lower phase halogenated hydrocarbon solvent phase is extracted, neutralized by adding 1.7 g of 5% NaOH aqueous solution, and concentrated to 40%, 60% or 80% by distillation to obtain a bottom liquid. Got Next, the concentrated bottom liquid was further distilled to produce distilled EDC. (E) Using the obtained solvent as a reaction solvent, the same polymerization reaction and sulfonation reaction as described above are performed, and the sulfonated product taken out from the upper phase part of the separating funnel is neutralized with a 10% aqueous NaOH solution to give polystyrenesulfone. Acid Na was obtained. Table 1 shows the solvent pH at the time of solvent recovery, the sulfonation conditions, and the properties of the obtained polystyrene sulfonate Na (PSS-Na) (No. 1 to No. 3). The weight average molecular weight of Na polystyrene sulfonate was 13,200 when the sulfonated product contained in the aqueous phase separated in step (C) was neutralized with a 10% aqueous NaOH solution.

COMPARATIVE EXAMPLE 1 The bottom phase separated in Example 1 was withdrawn and concentrated to 60% and 80% without neutralization, respectively.
Polystyrene sulfonate Na was obtained in the same manner as in the example except that was used (Nos. 4 and 5).

[0018]

[Table 1] Table-1 Properties of Na polystyrene sulfonate NO. 1 2 3 4 ^* 5 ^* Solvent pH Bottom EDC 7.0 5.0 4.0 2.9 2.4 Recovery EDC 6.5 6.1 5.1 3.5 3.0 Sulfonation conditions SO ₃ molar ratio 1.16 1.15 1.10 1.15 1.10 Temperature (℃) 40 40 41 40 41 Reaction retention time (min) 10 5 15 5 15 PSS-Na weight average molecular weight 13000 13300 12900 8500 7000 Yield (%) 99.9 99.9 99.9 99.9 99.9 No. 4 ^* and No. 5 ^* are comparative examples.

The pH of the solvent is adjusted by adding pure water in the same amount as that of the solvent and stirring the mixture sufficiently to extract the acid component into the aqueous phase.
Is a value obtained by measuring. The molecular weight of PSS-Na was measured by the following method. Standard sodium standard polystyrene sulfonate was used as a standard substance, and TSK G3000SW (7.5 mm manufactured by Tosoh Corp.) as a separation column.
ID × 30cm) and TSK G4000SW (7.5m
mID × 30 cm) and an ultraviolet ray detector (measurement wavelength: 238 nm) was used for the GPC method. When styrene sulfonate was detected in the sample, the styrene sulfonate was excluded and the weight average molecular weight was determined.

Example 2 (A) 2 Kg of 1,2-dichloroethane (EDC) was charged in the same reactor as in Example 1, and 4 g of tin tetrachloride and 0.7 g of pure water were added as catalysts. The temperature in the reactor was raised to 65 ° C with stirring, and 2K of styrene was added using a dropping funnel while controlling the temperature to 65 ° C.
g was added dropwise over 5 hours to carry out polymerization. Furthermore, after stirring for 4 hours, 2 Kg of EDC was added to the obtained polymerization solution, 10 g of calcium hydroxide was further added, and the mixture was stirred for 1 hour, and then filtered to remove solids to obtain a polystyrene solution. (B) To this polystyrene solution, 12 kg of EDC was added and diluted. This raw material solution was supplied to a sulfonation reactor together with sulfuric anhydride, and the sulfonation reaction was performed under the conditions of a sulfonating agent molar ratio to the raw material of 1.10, a reaction residence time of 5 minutes, and a reaction temperature of 45 ° C.

(C) The obtained sulfonated product was added to 5% NaO.
The solution was neutralized with an aqueous solution of H so that the pH of the aqueous phase became neutral, transferred to a separatory funnel and allowed to stand for 1 hour to separate into an aqueous phase and a halogenated hydrocarbon solvent phase. (D) Next, the separated lower phase halogenated hydrocarbon solvent phase was extracted, neutralized by adding 1.2 g of 5% NaOH aqueous solution, and distilled to a bottom of 40%, 60% and 80% respectively. A liquid was obtained. Next, the concentrated bottom liquid was further distilled to produce distilled EDC. (E) Using the obtained solvent as a reaction solvent, the same polymerization reaction and sulfonation reaction as described above are performed, and the sulfonated product taken out from the upper phase part of the separating funnel is neutralized with a 10% aqueous NaOH solution to give polystyrenesulfone. Acid Na was obtained. Table 2 shows the solvent pH at the time of solvent recovery, the sulfonation conditions, and the properties of the obtained polystyrene sulfonate Na (PSS-Na) (No. 6 to 8). The weight average molecular weight of Na polystyrene sulfonate was 26,000 when the sulfonated product contained in the aqueous phase separated in step (C) was neutralized with a 10% aqueous NaOH solution.

Comparative Example 2 The bottom phase separated in Example 2 was withdrawn, and the bottom distilled EDC was concentrated to 60% and 80% without neutralization, respectively.
Polystyrene sulfonate Na was obtained in the same manner as in Example 2 except that was used (Nos. 9 and 10).

[0023]

[Table 2] Table-2 Properties of Na polystyrene sulfonate ─────────────────────────────────── NO. 6 7 8 9 * 10 * Solvent pH Bottom EDC 9.2 7.4 5.5 2.9 2.4 Recovery EDC 6.8 6.8 6.5 3.5 3.0 PSS-Na Weight average molecular weight 26000 25600 25500 18200 14500 Yield (%) 99.9 99.9 99.9 99.9 99.9 No. 9 * and No .10 * is a comparative example.

Example 3 (A) The same reactor as in Example 1 was charged with 2 kg of EDC, and 1.0 kg of styrene monomer was further added. Further, 40 g of benzoyl peroxide (BPO) was added as an initiator, the temperature was immediately raised to the boiling point of the solvent, and polymerization was carried out for 10 hours. After completion of the polymerization, unreacted monomers were removed by distillation under reduced pressure, and EDC was added to prepare a polystyrene solution such that the polystyrene concentration was 8%. (B) the molar ratio of the sulfonating agent to the raw material is 1.10,
After the sulfonation reaction was carried out under the conditions of a reaction residence time of 5 minutes and a reaction temperature of 35 ° C., the reaction product was continuously fed to a stirring tank equipped with stirring blades for a residence time of 30 minutes to form a sulfonated product. Obtained.

(C) Further, water was added to the obtained sulfonated product so that the concentration of the sulfonated product in the aqueous phase was 20% by weight to dissolve the sulfonated product, which was transferred to a separatory funnel and allowed to stand for 2 hours. Then, the aqueous phase and the halogenated hydrocarbon solvent phase were separated. (D) Next, the separated lower phase halogenated hydrocarbon solvent phase was extracted, neutralized by adding 0.6 g of a 5% NaOH aqueous solution, and distilled to a bottom concentration of 40%, 60%, and 80%, respectively. A liquid was obtained. Next, the concentrated bottom liquid was further distilled to produce distilled EDC. (E) Using the obtained solvent as a reaction solvent, the same polymerization reaction and sulfonation reaction as described above are performed, and the sulfonated product taken out from the upper phase part of the separating funnel is neutralized with a 10% aqueous NaOH solution to give polystyrenesulfone. Acid Na was obtained. Table 3 shows the solvent pH at the time of solvent recovery, the sulfonation conditions, and the properties of the obtained polystyrene sulfonate Na (PSS-Na) (Nos. 11 to 13). Further, the weight average molecular weight of Na polystyrene sulfonate was 28,000 when the sulfonated substance contained in the aqueous phase separated in step (C) was neutralized with 10% NaOH aqueous solution.

Comparative Example 3 Bottom distilled EDC was withdrawn by extracting the lower phase separated in Example 3 and concentrating it to 60% and 80% without neutralization, respectively.
Polystyrene sulfonate Na was obtained in the same manner as in Example 3 except that was used (Nos. 14 and 15).

[0027]

[Table 3] Table 3 Properties of Na polystyrene sulfonate ──────────────────────────────────── NO. 11 12 13 14 * 15 * Solvent pH Bottom EDC 7.0 5.0 4.0 2.8 2.3 Recovery EDC 6.6 6.1 5.0 3.4 2.9 PSS-Na Weight average molecular weight 28000 27000 27000 19000 13000 Yield (%) 99.8 99.8 99.9 99.9 99.9 No. 14 * and No .15 * is a comparative example.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Tsuyoshi Yamada 1-3-7 Main Office, Sumida-ku, Tokyo Inside Lion Corporation

Claims (5)

[Claims] 1. A process of (A) polymerizing a polymerizable monomer in a halogenated hydrocarbon solvent to produce a polymer, and then obtaining a solution in which the polymer is dissolved with or without removal of solid content, (B) A step of contacting a sulfonating agent with the obtained polymer solution to sulfonate the polymer in the solution; (C) neutralizing the obtained sulfonated polymer solution, or without neutralizing it, adding water to the solution, The step of transferring the sulfonated polymer or its salt to the aqueous phase and separating the aqueous phase and the halogenated hydrocarbon solvent phase, (D) the pH of the separated solvent phase is 4 to 1
After adjusting to 0, the step of recovering the halogenated hydrocarbon solvent by distillation, and the step of (E) supplying the recovered solvent to the step (A) for reuse are adopted. Integrated manufacturing method of sulfonated polymer. 2. The method according to claim 1, wherein the halogenated hydrocarbon solvent is dichloroethane. 3. The method according to claim 1, wherein the polymerizable monomer is an aromatic vinyl monomer. 4. The method according to claim 3, wherein the polymerizable monomer is styrene. 5. The polymerization of the monomer in step (A) is cationic polymerization using a Lewis acid as a catalyst,
Water present in the halogenated hydrocarbon solvent in (A) is 5
The method according to claim 1, wherein the amount of water contained in the solvent is 0 to 1000 ppm, and the amount of water contained in the solvent recovered in step (D) is smaller than the amount of water present in step (A).