JPH0651747B2 - Method for producing water-soluble polymer salt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a water-soluble salt of a novel (co) polymer.

[Conventional technology]

Conventionally, inorganic pigments such as calcium carbonate, clay, titanium oxide and alumina, hydraulic inorganic materials such as cement and gypsum, fuels such as coal, coke and pitch, dispersants for dispersing dyes in water, or water treatment. Aqueous dispersants are generally widely used as scale inhibitors such as.

Examples of these aqueous dispersants include polyacrylic acid and its copolymers, olefins such as ethylene, isobutylene, amylene, hexene, and diisobutylene, and α, β-unsaturated dicarboxylic acid anhydride represented by maleic anhydride. In addition to polycarboxylic acid dispersants such as copolymers with and polycarboxylic acid salt polymers such as polymaleic acid,
Sulfonic acid dispersants such as salts of condensates of naphthalene sulfonic acid, sodium lignin sulfonate, sodium polystyrene sulfonate, and salts of copolymers of styrene sulfonic acid and maleic anhydride are known.

[Problems to be Solved by the Invention] In general, sulfonic acids of organic compounds and their derivatives are strong acids comparable to sulfuric acid, and are widely used industrially by taking advantage of their properties.

Further, since the salt is water-soluble, it is important as a surfactant for organic materials or inorganic materials.

However, most of the conventionally synthesized sulfonates are aromatic sulfonates, and few examples of aliphatic sulfonates are known.

Further, as described below, the polymer or copolymer having a sulfone group in the aliphatic skeleton of the present invention is not known at all.

The present inventors have conducted intensive studies to obtain a polymer or copolymer of a sulfonated compound having an aliphatic skeleton, and the sulfonated compound of an aliphatic diene has a double bond, and thus can be polymerized. The polymer of this sulfonated compound has extremely excellent surface activity, and in particular, has been found to have an excellent dispersing action for coal and cement, and has reached the present invention.

[Means for solving problems]

That is, in the present invention, a sulfonated product of an aliphatic diene having 4 to 7 carbon atoms is polymerized in the presence of an acidic compound catalyst, and a salt is formed on at least a part of the sulfonic groups present in the resulting polymer. The present invention provides a method for producing a characteristic water-soluble polymer salt.

Aliphatic dienes (hereinafter sometimes referred to as "aliphatic dienes") for synthesizing a sulfonated product of an aliphatic diene having two to four double bonds in the molecule used in the present invention and having 4 to 7 carbon atoms. ), For example, 1,3-butadiene, 1,2-butadiene, 1,2-pentadiene, 1,
3-pentadiene, 2,3-pentadiene, isoprene, 1,2-hexadiene, 1,3-hexadiene,
1,4-hexadiene, 1,5-hexadiene, 2,3
-Hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,2-heptadiene, 1,3-heptadiene, 1,4-heptadiene, 1 , 5-heptadiene,
1,6-heptadiene, 2,3-heptadiene, 2,5
-Heptadiene, 3,4-heptadiene, 3,5-heptadiene and the like, as well as various branched dienes having 4 to 7 carbon atoms.

These aliphatic dienes can be used alone or in combination of two or more.

Further, in the present invention, a sulfonated compound having a tricyclodecane skeleton or a triclodecene skeleton may be copolymerized with the aliphatic diene, and dicyclopentadiene is a typical example of the compound having these skeletons. (Hereinafter, these compounds may be referred to as “dicyclopentadiene”), but their skeletons are shown below.

(That is, tricyclo [5.2.1.0 ^2.6 ] decane or decene) Specific examples of such dicyclopentadiene include dicyclopentadiene and dimethyldicyclopentadiene.

These compounds can be used alone or in combination of two or more.

Various methods are conceivable for producing a sulfonated product of an aliphatic diene or dicyclopentadiene. For example, a double bond of these aliphatic diene or dicyclopentadiene is sulfonated by the method shown below. can do.

That is, the sulfonation reaction applied to unsaturated compounds, particularly unsaturated aliphatic or unsaturated alicyclic compounds, is described in Gilbert's book "Sulfonation and Related Reacton", Interscience. Publishers Incorporated (Interscience Publishers Inc.) (1965) provides a detailed overview, and Charles J. Norton et al., The Journal of Organic Chemistry. Chem
It can also be sulfonated by the addition reaction of sulfites to unsaturated bonds, as shown in the study of Istry, page 4158 (1968).

As the sulfonating agent in this case, an acidic sulfite, metasulfite or sulfite of an alkali metal is usually used alone or as a mixture.

The amount of the sulfonating agent is usually 0.1 to 4 mol, preferably 0.5 to 2 mol, and more preferably 1 to 1 mol of the aliphatic diene or dicyclopentadiene.
It is 1.5 mol. If it is less than 0.1 mol, the reaction yield will be low, while if it exceeds 4 mol, the formation of disulfonate will increase.

When the amount of the sulfonating agent is less than 1 mol with respect to 1 mol of the aliphatic diene or dicyclopentadiene, a mixture of a sulfonated derivative and a non-sulfonated derivative can be formed. Is, for example, n
-Using hexane or the like) or only the sulfonated product may be taken out from the mixture by distillation, or the mixture of the sulfonated product and the non-sulfonated product may be (co) polymerized by the method described below.

Also in this case, the sulfonated (co) polymer can be separated from the non-sulfonated (co) polymer by extraction (using e.g. n-hexane as solvent) or distillation.

In the sulfonation reaction, it is not always necessary to use a catalyst, but use of a catalyst such as an inorganic oxidizing agent is usually effective in improving yield and shortening reaction time. Examples of the inorganic oxidizing agent include nitrates, nitrites, chlorates, etc., and nitrates are particularly effective.

The amount of the inorganic oxidizing agent is not particularly limited, but is 0.02 to 0.15 mol, preferably 0.05 to 0.1 mol with respect to 1 mol of the aliphatic diene or dicyclopentadiene.
0.1 mol is effective.

Furthermore, it is preferable to use a suitable solvent in order to allow the reaction to proceed uniformly and smoothly.

Solvents that can be used advantageously include, for example, water or methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, tertiary
Examples include lower alcohols such as primary butyl alcohol, lower glycols, ketones, ethers, and esters.

These solvents can be used as a mixture of two or more kinds as appropriate. Above all, a mixed solvent of a lower alcohol and water, especially a mixed solvent of methyl alcohol and water is recommended as an excellent solvent.

The reaction temperature is usually 50 to 200 ° C, preferably 70 to 200 ° C.
It is carried out at 150 ° C., more preferably 90 to 130 ° C., and can be carried out under either atmospheric pressure or under pressure.

In order to suppress the progress of side reactions and reduce the production of inorganic salts, the pH of the reaction system is usually 2-9, preferably 5-7.
Keep on.

The content of the sulfone group in the sulfonated compound varies depending on the conditions of the sulfonation reaction and the like, but is usually at least 2 of the aliphatic dienes or dicyclopentadiene.
It is preferable that 0 mol% or more, preferably 40 mol% or more, is sulfonated from the viewpoint of dispersibility of the obtained composition.

Further, the obtained sulfonated product may be one in which a salt-forming compound is used as a sulfonating agent to form a salt at a sulfone group, or a salt may be formed prior to (co) polymerization. . In this case, the cation species of the sulfonated compound is not particularly limited, but hydrogen, alkali metal, alkaline earth metal, ammonium, amine and the like are preferable in order to make it water-soluble.

Examples of the alkali metal include sodium and potassium, and examples of the amine include alkylamine such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine, triethylamine, butylamine dibutylamine and tributylamine, ethylenediamine, diethylenetriamine and triethylenetetramine. Examples thereof include polyamine, morpholine and piperidine, and examples of the alkaline earth metal include calcium and magnesium.

Also, these cationic species can be exchanged with other cationic species by various ion exchange techniques.

Next, the (co) polymer of the sulfonated aliphatic diene (and the sulfonated dicyclopentadiene) used in the present invention means at least one kind of the sulfonated aliphatic diene. Or a random type copolymer obtained by copolymerizing the sulfonated product of the aliphatic diene and the sulfonated product of dicyclopentadiene.

The method for producing such a (co) polymer is as follows.

That is, the sulfonated aliphatic diene (and the sulfonated dicyclopentadiene) is (co) polymerized in the presence of an acidic compound catalyst. The reaction temperature is usually
The (co) polymer can be produced by carrying out a polymerization reaction at −20 to 300 ° C., preferably 80 to 180 ° C. for several hours to several tens hours.

In the above (co) polymerization reaction, a solvent for polymerization reaction can be used in order to smoothly carry out the reaction. As such a solvent for polymerization reaction, a polar solvent such as water or carbonization can be used as long as it does not hinder the (co) polymerization reaction. Arbitrary ones such as hydrogens and halogenated hydrocarbons can be used.

Examples of the acidic compound catalyst include sulfuric acid, phosphoric acid, hydrogen fluoride, boron trifluoride and its complex, aluminum chloride,
Examples thereof include Lewis acids such as aluminum bromide, tin tetrachloride, zinc chloride and titanium trichloride, and organic protic acids. Among them, sulfuric acid can be mentioned as a typical example.

In the present invention, when a sulfonated product of an aliphatic diene and a sulfonated product of dicyclopentadiene are copolymerized to obtain a copolymer, the copolymerization ratio of the two is such that the sulfonated product of an aliphatic diene / Sulfonated product (molar ratio) of dicyclopentadiene = 10 to 100/90 to 0, preferably 15 to 100/85 to 0, and aliphatic diene of 10 mol% or more is preferable from the viewpoint of dispersibility. .

In addition, when the sulfonated product of these aliphatic dienes (and the sulfonated product of dicyclopentadiene) is (co) polymerized, it is also possible to copolymerize other copolymerizable monomers.

Such copolymerizable monomers include aliphatic, alicyclic, aromatic hydrocarbons having an olefinic double bond, unsaturated amides, unsaturated alcohols, unsaturated ester unsaturated nitriles, unsaturated carboxylic acids and the like. Ester, unsaturated sulfonic acid and its ester, etc., or aliphatic, alicyclic, aromatic alcohol or phenol, or amino group, ester group nitrile group, carboxylic acid group, alcohol or diol having sulfonic acid group, etc. 1 type The above can be used in an arbitrary ratio. In particular, those obtained by copolymerizing an unsaturated carboxylic acid such as acrylic acid or methacrylic acid are preferable in terms of dispersibility.

By changing the type of comonomer used, the surfactant properties of the polymer can be changed.

In this case, when a copolymer is produced from the sulfonated product of the present invention and a copolymerizable monomer and the copolymer is used as a dispersant for solid fuel, in order to suppress foaming. Is 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more.

The molecular weight of the (co) polymer obtained by the present invention can be appropriately changed depending on the reaction conditions, particularly the type and amount of the acidic compound catalyst, the type and amount of the solvent or the reaction temperature, and the reaction time.

The weight average molecular weight of the thus obtained (co) polymer before forming a salt depends on the reaction conditions, particularly the type and amount of the acidic compound catalyst, and the type and amount of the solvent or reaction temperature, reaction time. Can be changed as appropriate.

For example, when a (co) polymer is used as a dispersant for solid fuel, it cannot be unambiguously determined because the characteristics vary depending on the type and particle size of the solid fuel, but the weight average molecular weight is usually 500 or more. More preferably, it is 1,000 or more, more preferably 2,000 to 100,0.
00 is particularly preferred.

When the (co) polymer of the sulfonated product of the present invention is used as a cement dispersant, the weight average molecular weight is 500.
The above is preferable, more preferably 2,000 or more, and particularly preferably 3,500 to 50,000.

The (co) polymer of the present invention can be exchanged with an acid type or a salt of alkali metal, alkaline earth metal, ammonium, amine or the like by an ion exchange method or a neutralization reaction.

Further, the (co) polymer thus obtained has the following properties when a salt is not formed in the sulfonated product prior to the (co) polymerization:
It is then neutralized in an aqueous alkaline solution such as sodium hydroxide, potassium hydroxide or aqueous ammonia to obtain a water-soluble (co) polymer salt in which at least a part of the sulfone group forms a salt.

The cation for forming a salt on the sulfone group of the (co) polymer used in the present invention, that is, the cation species of the sulfonate is not particularly limited, but in order to make it water-soluble, a hydrogen atom is necessary. , Alkali metal, alkaline earth metal,
Ammonium, amine and the like are preferable.

Examples of the alkali metal include sodium and potassium, and examples of the amine include methylamine, ethylamine, propylamine, dimethylamine, diethylamine, triethylamine, butylamine, dibutylamine, alkylamines such as tributylamine, ethylenediamine, diethylenetriamine and triethylenetetramine. Examples of the polyamine, morpholine, piperidine and the like, and examples of the alkaline earth metal include calcium and magnesium.

Also, these cationic species can be exchanged with other cationic species by various ion exchange techniques.

Thus, an aqueous solution of a water-soluble (co) polymer salt is prepared. In the present invention, a solid water-soluble (co) polymer salt is obtained by separating and drying these salts from the aqueous solution, if necessary. You can

The water-soluble (co) polymer salt of the present invention can be mutually exchanged with a salt of an acid type or an amine by an ion exchange method or a neutralization reaction.

Further, the degree of neutralization of the sulfone group may be appropriately selected within the range in which the (co) polymer salt is water-soluble or water-dispersible, and the sulfone groups may form different salts. .

The structure of the water-soluble (co) polymer salt obtained by the present invention is
It can be confirmed from the absorption of the sulfone group by the infrared absorption spectrum, and the composition ratio of these can be known by acid / alkali titration such as potential difference and electric conductivity.

Moreover, the structure can be confirmed by the presence of a dicyclopentane ring or the like by a nuclear magnetic resonance spectrum.

The water-soluble (co) polymer salt obtained by the present invention comprises at least one dispersant, and if necessary, a nonionic or anionic surfactant, a chelating agent, a defoaming agent, a freezing point depressant, and a wetting agent. , And other additives such as dispersants and the like, but not particularly limited, is added to a fine powder slurry such as a solid fuel having a concentration of 40 to 80% by weight.

At this time, since the viscosity of the slurry decreases as the added amount of the water-soluble (co) polymer salt increases, the added amount can be selected according to the desired viscosity. 0.01 to 10% by weight, preferably 0.05
The amount may be ˜5 wt%, but is preferably 0.05 to 1 wt% from the viewpoint of workability and economy.

As described above, the (co) polymer used in the present invention easily becomes water-soluble when a salt is formed, and when dicyclopentadiene is copolymerized, the (co) polymer has a cyclic structure of the component. Due to the hard structure, and because the lipophilicity is imparted to the molecule, an action such as strong adsorption to various lipophilic pigments can be obtained, and the dispersibility in various powders is greatly improved. In addition, the stability of the resulting slurry over time is also improved.

The water-soluble (co) polymer salt obtained by the present invention includes various inorganic pigments such as calcium carbonate, clay, titanium oxide, gypsum, alumina, silica, magnesia and cement, as well as coal, petroleum coke, pitch and charcoal. It is preferably used as a dispersant for fine powders of organic substances such as.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

In the examples,% is based on weight.

In addition, the weight average molecular weight described in the examples is obtained by converting the result determined by gel permeation chromatography (GPC) using a calibration curve prepared by using several types of polystyrene sulfonic acid having different molecular weights as standard substances. Is.

That is, the eluent was dissolved in a solution in which acetonitrile and a 0.5 N sodium sulfate aqueous solution were mixed at a weight ratio of 3: 7, and the eluent was used, and the column was TSK-GE manufactured by Toyo Soda Co., Ltd.
LG 3000SW and TSK-GEL G2000S
W was connected in series and was measured using a UV detection group.

From the obtained GPC chart Was calculated to determine the weight average molecular weight.

Example 1 1,3-pentadiene 1.00 was placed in a stainless steel autoclave with a capacity of 30 equipped with a stirrer and a thermometer.
0 g, 1,530 g of sodium bisulfite, 62.5 g of potassium nitrate, 3 of methyl alcohol, and 1,500 g of distilled water were put, and nitrogen was supplied at a constant temperature until the internal pressure in the autoclave became 1.0 kg / cm ² · G. The valve was sealed, and the mixture was reacted under vigorous stirring at 110 ° C. for 5 hours.

After cooling to room temperature, most of the methyl alcohol was removed by distillation, distilled water and petroleum ether were added and mixed well, and the separated petroleum ether layer and the precipitated portion were removed and the resulting aqueous layer was concentrated. And distilled to dryness. This was dissolved in glacial acetic acid, and an acetic acid insoluble matter consisting of an inorganic salt was separated by a centrifuge.

The obtained acetic acid-soluble component was concentrated to obtain 1,200 g of a white solid. This is designated as a sulfonated product A.

Then, 1.0 g of the sulfonate A was placed in a 5.0 glass-lined autoclave equipped with a stirrer.
g, 1.0 kg of sulfuric acid and 0.45 kg of water were charged, and a polymerization reaction was carried out at 120 ° C. for 12 hours.

After completion of the reaction, riming was carried out with calcium carbonate to remove sulfuric acid, and the solid content obtained was 0.9 kg.

The molecular weight distribution of this product is shown in FIG. 3 as a GPC chart. The weight average molecular weight calculated from this is 9,80
It was 0.

In addition, the infrared absorption spectrum chart (I
The R chart) is shown in FIG. 1, and it is recognized that it has a sulfone group, and the surface tension of a 4% aqueous solution of this is 6
It was as high as 3.8 dyn / cm.

24 g of the obtained polymer was dissolved in 1,000 g of water,
Strongly acidic cation exchange resin 1,0 converted into acid form
After being placed in 00 g and allowed to stand for a whole day and night, the filtrate obtained by removing the resin by filtration was dried.

The obtained solid content was 18 g.

An elemental analysis of this product revealed that it had a carbon content of 39.0.
%, Hydrogen 6.6%, sulfur 22.1%, oxygen 32.3%, theoretical value of the polymer of the present invention, carbon 40.0%, hydrogen 6.7%, sulfur 21.3%, oxygen It was in very good agreement with 32.0%.

Next, when this was subjected to neutralization titration with sodium hydroxide, it was neutralized with an equivalent amount of sodium hydroxide. From these results, the polymer after the cation exchange treatment was converted into the sodium salt after the sulfone group was neutralized.

The surface tension of a 4% aqueous solution of this polymer salt is 64.2 dy.
It was n / cm.

Example 2 When the acid-type polymer of Example 1 was neutralized with potassium hydroxide, calcium hydroxide, aqueous ammonia, and monoethanolamine, the neutralization was completed in an equivalent amount. Water was removed from these under reduced pressure to separate the polymer. These are polymers of sodium salt, calcium salt, ammonium salt, or monoethanolamine salt.

The GPC chart and IR chart of these polymers were almost the same as those in Example 1.

In addition, as a result of elemental analysis of these polymers, potassium salt,
It was confirmed that (calcium) 1/2 salt, ammonium salt, monoethanolamine salt, etc. were contained in an equivalent amount with respect to the sulfone group.

Example 3 In Example 1, the polymer was obtained by setting the polymerization temperature to 130 ° C.

The weight average molecular weight of this product was 14,300, and spectra similar to the IR chart and GPC chart shown in FIGS. 1 and 2 were obtained.

The surface tension of a 4% aqueous solution of this product is 64.6.
It was dyn / cm.

Example 4 In Example 1, the polymer was obtained by setting the polymerization temperature to 100 ° C.

The weight average molecular weight of this product is 5,200, and
Spectra similar to the IR chart and GPC chart shown in the figure and FIG. 3 were obtained.

The surface tension of this 4% aqueous solution is 60.3 dy.
It was n / cm.

Example 5 In a stainless steel autoclave having a capacity of 30 equipped with a stirrer and a thermometer, dicyclopentadiene 3,000 was added.
After adding 0 g, sodium bisulfite 1,888 g, potassium nitrate 91.7 g, methyl alcohol 12 and distilled water 3,000 g, and supplying nitrogen until the internal pressure in the autoclave became 1.0 kg / cm ² · G at room temperature, The valve was sealed, and the reaction was carried out at 130 ° C. for 5 hours while mixing with vigorous stirring.

After cooling to room temperature, most of the methyl alcohol was removed by distillation, distilled water and n-hexane were added and mixed well, and the separated n-hexane layer and the precipitated portion were removed to obtain an aqueous layer. Was concentrated and distilled to dryness.

After drying, it was dissolved in glacial acetic acid, and acetic acid insoluble matter such as inorganic salts was filtered off.

The obtained acetic acid-soluble component was coagulated to dryness to obtain a white-yellow solid. This solid was washed with ethanol and further dried to give a sulfonated product of dicyclopentadiene 2,40
I got 0 kg. This is designated as sulfonate B.

Then, into a 5.0 glass-lined autoclave equipped with a stirrer, 0.7 kg of the sulfonate A obtained in Example 1, 0.3 kg of the sulfonate B, 1.0 kg of sulfuric acid, 0.45 kg of water were placed. Was charged and the polymerization reaction was carried out at 120 ° C. for 12 hours.

After completion of the reaction, riming was carried out with calcium carbonate to remove sulfuric acid, and the solid content obtained was 0.9 kg.

The molecular weight distribution of the obtained copolymer is shown in FIG. 4 (GPC chart). The weight average molecular weight calculated from this is
It was 13,200.

In addition, the infrared absorption spectrum chart (I
The R chart) is as shown in FIG. 2, and it is recognized that the compound has a sulfone group, and the surface tension of a 4% aqueous solution of this was as high as 70.3 dyn / cm.

24 g of the obtained copolymer was dissolved in 1,000 g of water, and this was put in 1,000 g of a strongly acidic cation exchange resin converted into an acid form. After standing for one day and night, the above resin was filtered off. The liquid was dried.

The obtained solid content was 17 g.

An elemental analysis of this product revealed that carbon 52.5
%, Hydrogen 5.8%, sulfur 16.8%, oxygen 24.9%, theoretical value of the polymer of the present invention, carbon 52.8%, hydrogen 5.7%, sulfur 16.6%, oxygen It was extremely close to 24.9%.

Next, when this was subjected to neutralization titration with sodium hydroxide, it was neutralized with an equivalent amount of sodium hydroxide. From these results, the polymer after the cation exchange treatment was converted into the sodium salt after the sulfone group was neutralized.

Use example 1 (Coal dispersibility test) Coal is from Australia and is 200 mesh pass for 7
A material containing 6% of ash, 6.5% of ash and 1.6% of sulfur was used.

The dispersant described in Examples 1, 3, 4, and 5 (vs. coal 0.5
%) And gradually add a predetermined amount of coal particles into it,
A coal slurry having a concentration of 70% was prepared by stirring with a homomixer at 3,000 rpm for 15 minutes. The viscosity of the coal slurry thus obtained was measured at 25 ° C.

The evaluation results are shown in Table 1.

The slurry viscosity was measured in the same manner as above except that no dispersant was added.
It was over 10,000 cps.

USE EXAMPLE 2 2 g of each of the dispersants described in Examples 1, 3, 4, 5
6 g of distilled water was added and dissolved to prepare three kinds of aqueous solutions in total.

To each of these aqueous solutions, 200 g of commercially available Portland cement (manufactured by Chichibu Cement Co., Ltd.) was added and kneaded for 3 minutes, and then a flow cone with an internal volume of 98.9 cc was used.
The result of measuring the flow value according to R5201
Shown in the table.

The flow value was measured in the same manner as above except that no dispersant was added.
It was 10 mm.

〔The invention's effect〕

The water-soluble (co) polymer salt obtained by the present invention has excellent dispersibility in any of inorganic substances such as inorganic pigments and hydraulic inorganic materials, coal, pitch, and organic substances such as coke,
Further, it is possible to provide a novel dispersant that imparts excellent temporal stability to the obtained slurry and has almost no coloration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an infrared absorption spectrum of the polymer salt shown in Example 1, FIG. 2 is an infrared absorption spectrum of the copolymer salt shown in Example 5, and FIG. The GPC chart of the polymer salt shown in FIG. 4 is the GPC chart of the copolymer salt shown in Example 5.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshinori Yoshida, 2-11-24 Tsukiji, Chuo-ku, Tokyo Within Nippon Synthetic Rubber Co., Ltd. (56) References JP 54-129031 (JP, A) KO46-21644 (JP, B1)

Claims (2)

[Claims] 1. A sulfonation product of an aliphatic diene having 4 to 7 carbon atoms is polymerized in the presence of an acidic compound catalyst, and a salt is formed on at least a part of sulfo groups present in the resulting polymer. And a method for producing a water-soluble polymer salt. 2. The method for producing a water-soluble polymer salt according to claim 1, wherein the aliphatic diene is 1,3-pentadiene.