JP2002302521A - Anionic water-soluble polymer dispersion and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable dispersion of a high-molecular weight sulfa- containing anionic water-soluble polymer,and to provide a method for producing the above polymer dispersion under easy control by dispersion polymerization process in an aqueous salt solution in the presence of a polymeric dispersant soluble to the aqueous salt solution. SOLUTION: This anionic water-soluble polymer dispersion is obtained by dispersion polymerization process for a water-soluble monomer mixture comprising 1-30 mol% of a sulfo-containing monomer, 5-50 mol% of a carboxy group- containing monomer, 20-94 mol% of a (meth) acrylamide and 0-20 mol% of another copolymerizable monomer in an aqueous salt solution in the presence of a polymeric dispersant soluble to the aqueous salt solution, wherein a redox system as the polymerization initiator is preferably used at 5-50 ppm based on the monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high polymerization degree anionic water-soluble polymer dispersion and a method for producing the same. The present invention relates to a dispersion of a water-soluble polymer produced by a dispersion polymerization method of a monomer mixture containing a sulfonic acid group below, and to a method for producing the dispersion.

[0002]

2. Description of the Related Art Anionic water-soluble polymers have been applied to a wide variety of uses as flocculants. For example, it is used as a general water treatment agent for solid-liquid separation in wastewater, and is also used in combination with a cationic coagulant as a dewatering agent for sludge or as a retention improver in the papermaking industry. In civil engineering, it is also used as a solidifying agent for soil. Conventionally, the following polymerization methods are known as methods for producing these anionic polymers. For example, the aqueous solution polymerization method is supplied as a product on a paste, and the water-in-oil emulsion polymerization product is supplied in the form of a latex by adding a hydrophilic emulsifier called a phase inversion agent after polymerization, and is supplied in the form of a water-in-oil dispersion weight. The method is often applied to produce a powdery product. A method of directly polymerizing a 30-50% by weight aqueous monomer solution, granulating a gel polymer with a meat chopper, etc., and then directly drying the solution. Has also been applied to the production of powdered products. More recently, monomers have been dissolved and polymerized in aqueous polyethylene glycol solutions,
Although a method for producing a polymer-in-polymer dispersion liquid has been performed, a high-molecular-weight flocculant having practical performance as a flocculant has not yet been synthesized. It should be further noted that attempts have been made to develop a method for synthesizing a cationic / amphoteric flocculant in an aqueous salt solution, and to synthesize an anionic polymer having a degree of polymerization of a flocculant grade.

One of the reasons that anionic polymers having a high degree of polymerization are more difficult to synthesize by a dispersion polymerization method in an aqueous salt solution than cationic polymers having a high degree of polymerization is that the polymer is precipitated in salt water. To obtain a stable dispersion. In the case of a cationic monomer, if a monomer having a hydrophobic group such as a benzyl group or a long-chain alkyl group is synthesized, a polymer insoluble in salt water can be easily synthesized. It will be usable. In the case of anionic monomers, it is difficult to introduce a hydrophobic group into the molecule itself, so a method of copolymerizing hydrophobic monomers is considered. In many cases, it is not possible to obtain a product with a high value. Another factor is that the molecular weight of acrylic acid mainly used as a raw material is smaller than the molecular weight of the cationic monomer, and the calorific value per weight concentration of the solution is very large. Therefore, it is difficult to control the polymerization reaction, and the reactants agglomerate during the polymerization, so that a stable dispersion cannot be synthesized. Alternatively, a large calorific value means that it is not easy to control the polymerization temperature, the temperature of the polymerization system falls outside the control range, and the degree of polymerization of the generated anionic water-soluble polymer is reduced. . At present, the method of precipitating the produced anionic water-soluble polymer in salt water is being solved by combining various salts, and the dispersion liquid is also stabilized by using an ionic polymer dispersant of various compositions. It became possible by examining the molecular weight and coexisting. However, a dispersion of an anionic water-soluble polymer containing a sulfonic acid group in salt water has not yet been studied.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-molecular weight sulfonic acid group-containing anionic water-soluble compound in a salt solution in the presence of a polymer dispersant soluble in the salt solution by a dispersion polymerization method. An object of the present invention is to develop a method for efficiently producing a polymer dispersion in salt water in a stable dispersion state.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted detailed studies, and as a result, have made it possible to form a high molecular weight sulfonic acid group by allowing the reaction to proceed under specific polymerization conditions. It can be seen that the contained anionic water-soluble polymer can be efficiently produced in a stable dispersion state,
The present invention has been completed. That is, the invention of claim 1 of the present invention is characterized in that 1 to 30 mol% of a sulfonic acid group-containing monomer represented by the following general formula (1) and a carboxyl group-containing monomer 5 represented by the following general formula (2) ~ 50 mol%, (meth)
A water-soluble monomer mixture containing 20 to 94 mol% of acrylamide and 0 to 20 mol% of another copolymerizable monomer is allowed to coexist in a salt aqueous solution with a polymer dispersant soluble in the salt aqueous solution. The present invention relates to an anionic water-soluble polymer dispersion comprising polymer fine particles having a particle size of 100 μm or less produced by a dispersion polymerization method.

Embedded image R1 is hydrogen, R3 is hydrogen or carboxyl group, A is S
O3, C6H4SO3, CONHC (CH3) 2CH2
SO3, CONHC2H4 SO3 or COOC2H
4SO3, X is a cation

Embedded image R2 is hydrogen, methyl or carboxymethyl, R3
Is hydrogen or carboxyl group, A is COO or C6H
4COO, Y is a cation

[0006] The invention of claim 2 is the anionic water-soluble polymer dispersion according to claim 1, wherein the polymer dispersant is anionic.

A second aspect of the present invention is the anionic water-soluble polymer dispersion according to the second aspect, wherein the high molecular dispersant has an ion equivalent of 1.5 to 15 meq / g.

According to a fourth aspect of the present invention, the weight average molecular weight of the anionic water-soluble polymer constituting the anionic water-soluble polymer dispersion is from 2,000,000 to 20,000,000. 3. The anionic water-soluble polymer dispersion described in 1. above.

The invention according to claim 5 is the anionic water-soluble polymer dispersion according to claim 1, wherein the salt constituting the salt aqueous solution contains at least one kind of polyvalent anion salt.

The invention according to claim 6 is characterized in that 1 to 30 mol% of a sulfonic acid group-containing monomer represented by the following general formula (1):
5 to 50 mol% of (meth) acrylic acid, 20 to 94 mol% of (meth) acrylamide and 0 other copolymerizable monomers
A polymer mixture having a particle size of 100 μm or less, characterized in that a water-soluble monomer mixture containing モ ル 20 mol% is subjected to dispersion polymerization in a salt aqueous solution in the presence of a polymer dispersant soluble in the salt aqueous solution. Is a method for producing an anionic water-soluble polymer dispersion.

[0011] The invention of claim 7 is a method for producing the water-soluble monomer mixture by a dispersion polymerization method in which a possible ionic polymer dispersant coexists in a salt aqueous solution. 7. The polymerization is started.
3. The method for producing an anionic water-soluble polymer dispersion described in 1. above.

The invention of claim 8 is the method for producing an anionic water-soluble polymer dispersion according to claim 6, wherein the polymer dispersant is anionic.

According to a ninth aspect of the present invention, there is provided the method for producing an anionic water-soluble polymer dispersion according to the eighth aspect, wherein the high molecular dispersant has an ion equivalent of 1.5 to 15 meq / g. It is.

According to a tenth aspect of the present invention, there is provided the method for producing an anionic water-soluble polymer dispersion according to the sixth aspect, wherein the salt constituting the aqueous salt solution contains at least one kind of polyvalent anion salt. It is.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A water-soluble monomer or a mixture of water-soluble monomers is prepared by a dispersion polymerization method in a salt aqueous solution in which a possible ionic polymer dispersant coexists in the salt aqueous solution. A method for producing a dispersion liquid composed of molecules is disclosed in
It can be manufactured by the method described in JP-A-39481 and JP-B-6-51755. The former publication discloses a method in which a polyhydric alcohol coexists as a dispersant during polymerization, and the latter publication discloses a method in which a cationic polymer soluble in an aqueous polyvalent anion salt solution is used as a dispersant during polymerization. A method is disclosed. These publications include:
It is necessary that a polymer or copolymer of a (meth) acryloyloxyethyltrialkylammonium chloride monomer such as acryloyloxyethyltrimethylammonium chloride be used as a dispersant during the polymerization.

Hereinafter, the manufacturing method will be specifically described. A monomer comprising a sulfonic acid group-containing monomer, (meth) acrylic acid, (meth) acrylamide and another copolymerizable monomer used as a raw material is dissolved in an aqueous salt solution, and the total anionic monomer is dissolved. Neutralize 5-20 mol% of the body with alkali. Thereafter, a dispersant comprising an ionic polymer as described above is added, and after substitution with nitrogen, polymerization is started with a radical polymerization initiator and polymerization is performed with stirring.

The temperature during the polymerization is 5 to 30 ° C., preferably 15 to 30 ° C. In the case of polymerizing a cationic water-soluble polymer, the temperature of the aqueous monomer solution is set at 30 to 35 ° C, and the solution concentration is 20 to 35% by weight, and 2,2-azobis [2- (5-methyl-2- Imidazolin-2-yl) propane] dihydrochloride and the like in an amount of 50 to 1 per monomer.
The polymerization can be started by adding 50 ppm. However, when copolymerizing a sulfonic acid group-containing monomer, (meth) acrylic acid and acrylamide, it is difficult to control the polymerization if started under these conditions, and a sharp rise in temperature or agglomeration of the polymerization solution occurs. A stable dispersion with a high degree of polymerization does not form. Therefore, in the present invention, the initiation temperature is set at 5 to 30 ° C, preferably 10 to 30 ° C, and the polymerization is started.

The polymerization is initiated at a low temperature, 2,2-azobis [2-
(5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride or 4,4-azobis (4-
An azo-based polymerization initiator such as methoxy-2,4dimethyl) valeronitrile can be used, but it is difficult to start unless the amount of addition is large. Therefore, if the temperature of the polymerization system rises even slightly, the polymerization rate is accelerated and it is difficult to control. Therefore, a redox-based initiator which is added in a small amount and can be started at a low temperature is used. The amount of the initiator added is 10 to 50 ppm, preferably 10 to 30 pp, per monomer at the start of polymerization.
m. Usually, when the monomer concentration is low, the polymerization does not start at this initiator addition amount and temperature. However, in the present invention, since the dispersion polymerization method in an aqueous salt solution is used, the monomer concentration is 20 to 35% by weight, and it is presumed that the polymerization is started because of a relatively high concentration. However, due to the low level of addition, a single addition results in a lower polymerization rate. Therefore, it is preferable to add it several times. The number of additions is 2 to 5
Times, preferably 2-3 times.

As the redox initiator, an oxidizing substance and a reducing substance are combined. Examples of oxidizing substances include ammonium peroxodisulfate, potassium peroxodisulfate, and hydrogen peroxide.Examples of reducing substances include sodium sulfite, sodium bisulfite, ferrous sulfate, sodium thiosulfate, sodium oxalate, Examples thereof include triethanolamine and tetramethylethylenediamine, and among them, a combination of ammonium peroxodisulfate and sodium bisulfite is most preferable. In this way, by controlling the addition level of the initiator at a relatively low temperature, the polymerization rate can be controlled to produce a stable polymer dispersion having a high degree of polymerization. The molecular weight of the anionic water-soluble polymer produced in this way is usually 2,000,000 or more, and by selecting the conditions, 5,000,000 to 20,000,000 can be produced, which can sufficiently withstand use as a flocculant. is there.

Among the anionic monomers used, examples of the sulfonic group-containing monomer include vinyl sulfonic acid, vinyl benzene sulfonic acid and 2-acrylamide 2-acrylamide.
And methyl propane sulfonic acid. Examples of the carboxyl group-containing monomer are methacrylic acid, acrylic acid,
Examples include itaconic acid, maleic acid, and p-carboxystyrene. Further, the polymer dispersion may be a copolymer with another nonionic monomer. For example, (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide And the like, and copolymerization with one or more of these is possible. The most preferred combination is 2-acrylamide 2-methylpropanesulfonic acid, acrylic acid and acrylamide.

The molar ratio of the sulfonic acid group-containing monomer in the polymer constituting the polymer dispersion is 1 to 30 mol%, preferably 2 to 15 mol%. If it exceeds 30 mol%, dissociation polymerization cannot be performed due to strong dissociation of sulfonic acid groups. If the amount is less than 1 mol%, the effect of the sulfonic acid group will not be easily exhibited. The molar ratio of the sulfonic acid group-containing monomer is from 5 to 50 mol%, and preferably from 5 to 30 mol%. Further, the molar ratio of acrylamide is from 20 to 94 mol%, and more preferably from 55 to 93 mol%. Further, a copolymerizable nonionic monomer can be copolymerized. The amount is 0 to 20 mol%
It is.

The polymer dispersant used may be ionic or non-ionic, but is preferably ionic. First, as the cationic polymer, there are cationic monomers such as (meth) acryloyloxyethyltrimethylammonium chloride and dimethyldiallylammonium chloride. Can also be used. Examples of nonionic monomers include acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetoneacrylamide, 2-hydroxyethyl (meth) acryle And a copolymer with acrylamide is preferred.

On the other hand, as the anionic dispersion, a (co) polymer of an anionic monomer such as acrylamide 2-methylpropanesulfonic acid (salt) or styrenesulfonic acid (salt) can be used. These anionic monomers and carboxyl group-containing monomers, for example, acrylic acid, methacrylic acid,
Copolymers with itaconic acid and the like can also be used. Further, non-ionic monomers such as acrylamide, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, acrylonitrile, diacetoneacrylamide, and 2-hydroxyethyl (meth) acryle Copolymers such as those described above can also be used. Further, a partially amidated maleic anhydride / butene copolymer may be used.

Examples of the nonionic polymer include polyvinylpyrrolidone, acrylamide / polyvinylcaprolactam copolymer, acrylamide / styrene copolymer,
A water-soluble polymer having an amide group and some hydrophobic groups, such as a complete amidated maleic anhydride / butene copolymer, is effective.

The molecular weight of these cationic or anionic polymer dispersants is from 5,000 to 2,000,000,
Preferably it is 50,000 to 1,000,000. The molecular weight of the nonionic polymer dispersant is 1,000 to 100,000, and preferably 1,000 to 50,000. The amount of the nonionic or ionic polymer dispersant added to the monomer is 1/100 to 1/10, preferably 2/100 to 6/100, based on the monomer.

The salts used include salts of alkali metal ions such as sodium and potassium or ammonium ions with halide ions, sulfate ions, nitrate ions, phosphate ions, etc., and salts with polyvalent anions. Is more preferred. The salt concentration of these salts is from 7% by weight to
Can be used up to saturation concentration.

The anionic water-soluble polymer comprising the dispersion produced by the dispersion polymerization method used in the present invention was produced by an aqueous solution polymerization method, a water-in-oil emulsion polymerization method, or a water-in-oil dispersion polymerization method. The apparent viscosity when dissolved in water is very low as compared with the anionic polymer. For example, in the case of a copolymer containing sodium acrylate and acrylamide at a molar ratio of 30/70, the viscosity of an aqueous solution having a molecular weight of about 13,000,000 and 0.2% by weight is determined by an aqueous solution polymerization method and a water-in-oil emulsion polymerization method. In the polymer produced by the water-in-oil dispersion polymerization method, the pressure is 400 to 800 mPa · s, whereas the anionic water-soluble polymer composed of the dispersion liquid produced by the dispersion polymerization method used in the present invention is 20 to 20 mPa · s. 100mPa ・
s. This is affected by inorganic salts coexisting during polymerization. Further, 10 to 20 of the monomers used during the polymerization are used.
One factor is that it only neutralizes mole%. However, these effects alone cannot be explained. It is presumed that this phenomenon is caused by polymerization while precipitating the polymer formed in the aqueous salt solution, but the detailed mechanism has not been elucidated. Therefore, a low apparent viscosity means that the dispersibility in water for the purpose of treatment is good and the coagulation function can be sufficiently exhibited. For example, when it is applied as a filler retention improver, an addition place closer to a papermaking machine can be selected. As an example, even if it is added at a place closer to the machine such as a screen outlet, it can be said that the risk of trouble due to uneven dispersion is low. Further, sludge having a concentration of 15,000 to 30,000 mg / L or the like, in which the dispersibility of the added flocculant is deteriorated, can be sufficiently dispersed, and the effect can be exhibited.

[0028]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the present invention is not limited to the following Examples unless it exceeds the gist thereof.

[0029]

EXAMPLE 1 137.4 g of deionized water and 110.8 g of ammonium sulfate were placed in a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube.
g, sodium sulfate 25.6 g, 2-acrylamide 2
-Methylpropanesulfonic acid 16.6 g, 60% acrylic acid: 28.8 g, 50% acrylamide: 181.8 g
7 g was added, and 16 mol% of the anionic monomer was neutralized with 6.8 g of 30 wt% sodium hydroxide. Also 15
After neutralizing 90 mol% of the acid with a monomer mixture aqueous solution of methacrylic acid / acrylamide 2-methylpropanesulfonic acid = 3/7 (molar ratio) by weight%, a copolymer aqueous solution produced by polymerization was prepared ( Solution viscosity 42, 600 mPa.
s) 25.0 g were added. Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. Thirty minutes after the introduction of nitrogen, 0.1 g of a 0.1 wt% aqueous solution of ammonium peroxodisulfate and 0.1 wt% of an aqueous solution of ammonium bisulfite were added in this order, 2.5 g (based on monomer, 20 ppm), respectively, to initiate polymerization. Six hours after the start of the polymerization, the same amount of the initiator was added, and the polymerization was continued for another 15 hours to complete the reaction. This prototype is referred to as prototype-1. The molar ratio of 2-acrylamide 2-methylpropanesulfonic acid / acrylic acid / acrylamide of this prototype 1 was 5/15/80, and the viscosity was 830 mPa · s.
Met. As a result of microscopic observation, it was found that the particles had a size of 5 to 50 μm. In addition, the weight average molecular weight was measured by a molecular weight measuring device (DLS-7000 manufactured by Otsuka Electronics Co., Ltd.) by a static light scattering method. Table 1 shows the results.

[0030]

Example 2 In a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube, 113.4 g of deionized water and 115.0 g of ammonium sulfate.
g, sodium sulfate 20.4 g, 2-acrylamide 2
-Methylpropanesulfonic acid 10.3 g, 60% acrylic acid: 23.8 g, 50% acrylamide: 200.
5 g were added, and 22 mol% of the anionic monomer was neutralized with 7.3 g of 30 wt% sodium hydroxide. Also 15
After neutralizing 90 mol% of the acid with a monomer mixture aqueous solution of methacrylic acid / acrylamide 2-methylpropanesulfonic acid = 3/7 (molar ratio) by weight%, a copolymer aqueous solution produced by polymerization was prepared ( Solution viscosity 42, 600 mPa.
s) 33.3 g were added. Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. Thirty minutes after the introduction of nitrogen, 0.1 g of a 0.1 wt% aqueous solution of ammonium peroxodisulfate and 0.1 wt% of an aqueous solution of ammonium bisulfite were added in this order, 2.5 g (based on monomer, 20 ppm), respectively, to initiate polymerization. At 6 hours after the start of the polymerization, the same amount of the initiator was added, and the polymerization was continued for another 15 hours to complete the reaction. This prototype is referred to as prototype-1. The molar ratio of 2-acrylamide 2-methylpropanesulfonic acid / acrylic acid / acrylamide of this prototype-2 was 3/12/85, and the viscosity was 915 mPa · s.
Met. As a result of microscopic observation, it was found that the particles had a size of 5 to 60 μm. Also, the weight average molecular weight was measured in the same manner. Table 1 shows the results.

[0031]

Example 3 A four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube was charged with 138.0 g of deionized water and 115.0 g of ammonium sulfate.
g, sodium sulfate 20.4 g, 2-acrylamide 2
30.4 g of methylpropanesulfonic acid, 53.0 g of 60% acrylic acid, 125% of acrylamide: 125.
2 g were added and 22 mol% of the anionic monomer was neutralized with 7.9 g of 30% by weight sodium hydroxide. Also 15
After neutralizing 90 mol% of the acid with a monomer mixture aqueous solution of methacrylic acid / acrylamide 2-methylpropanesulfonic acid = 3/7 (molar ratio) by weight%, a copolymer aqueous solution produced by polymerization was prepared ( Solution viscosity 42, 600 mPa.
s) 33.3 g were added. Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. Thirty minutes after the introduction of nitrogen, 3.1 g (relative to the monomer, 25 ppm) of a 0.1% by weight aqueous solution of 0.1% by weight of ammonium peroxodisulfate and ammonium hydrogen sulfite were added in this order to initiate polymerization. Six hours after the start of the polymerization, the same amount of the initiator was added, and the polymerization was continued for another 15 hours to complete the reaction. This prototype is referred to as prototype-1. The molar ratio of 2-acrylamide 2-methylpropanesulfonic acid / acrylic acid / acrylamide of this prototype-3 was 10/30/60, and the viscosity was 1100 mPa.
-It was s. In addition, as a result of microscopic observation, 5 to 40 μm
Particles. Also, the weight average molecular weight was measured in the same manner. Table 1 shows the results.

[0032]

Example 4 The same procedure as in Examples 1 to 3 was used to synthesize a prototype-4 composed of 2-acrylamide 2-methylpropanesulfonic acid / acrylic acid / acrylamide = 2/5/93. The viscosity of this prototype-4 was 945 mPa · s. In addition, as a result of microscopic observation, it turned out that it is a particle of 5-40 micrometers. The molecular weight was measured in the same manner.
Table 1 shows the results.

[0033]

Example 5 Acrylamide 2-
Prototype-5 having a molar ratio of methylpropanesulfonic acid / acrylic acid / acrylamide = 15/30/55 was synthesized. The viscosity of this prototype-5 was 945 mPa · s. As a result of microscopic observation, it was found that the particles had a size of 5 to 60 μm. The molecular weight was measured in the same manner. Table 1 shows the results.

[0034]

Example 6 A four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube was charged with 137.4 g of deionized water and 110.8 g of ammonium sulfate.
g, sodium sulfate 25.6 g, 2-acrylamide 2
-Methylpropanesulfonic acid 16.6 g, 60% acrylic acid: 28.8 g, 50% acrylamide: 181.8 g
7 g were added and 5 mol% of the anionic monomer was neutralized with 2.1 g of 30% by weight sodium hydroxide. Polyvinylpyrrolidone (molecular weight 10,000) as a polymer dispersant
Dissolved in 25% by weight (based on monomer 8.
5% by weight). Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. Nitrogen introduction 30
After one minute, 2.5 g of a 0.1% by weight aqueous solution of ammonium peroxodisulfate and ammonium hydrogen sulfite was added in this order in 2.5 g (based on monomer, 20 ppm) to initiate polymerization. Six hours after the start of the polymerization, the same amount of the initiator was added, and the polymerization was continued for another 15 hours to complete the reaction. This prototype is referred to as prototype-6. The molar ratio of 2-acrylamide 2-methylpropanesulfonic acid / acrylic acid / acrylamide of this prototype-1 was 5/15/80, and the viscosity was 1630 mPa · s.
Met. As a result of microscopic observation, it was found that the particles had a size of 5 to 80 μm. In addition, the weight average molecular weight was measured by a molecular weight measuring device (DLS-7000 manufactured by Otsuka Electronics Co., Ltd.) by a static light scattering method. Table 1 shows the results.

[0035]

Comparative Example 1 A four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube was charged with 137.4 g of deionized water and 110.8 g of ammonium sulfate.
g, sodium sulfate 25.6 g, 2-acrylamide 2
-Methylpropanesulfonic acid 16.6 g, 60% acrylic acid: 28.8 g, 50% acrylamide: 181.8 g
7 g was added, and 16 mol% of the anionic monomer was neutralized with 6.8 g of 30 wt% sodium hydroxide. Also 15
After neutralizing 90 mol% of the acid with a monomer mixture aqueous solution of methacrylic acid / acrylamide 2-methylpropanesulfonic acid = 3/7 (molar ratio) by weight%, a copolymer aqueous solution produced by polymerization was prepared ( Solution viscosity 42, 600 mPa.
s) 25.0 g were added. Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. Thirty minutes after the introduction of nitrogen, 1.3 g of a 1.0% by weight aqueous solution of 1.0% by weight of ammonium peroxodisulfate and ammonium bisulfite were added in this order (based on the monomer, 100 ppm).
It was added to start polymerization. About 3 hours after the start of the polymerization, the reaction product became thickened violently and was wrapped around the stirring propeller. Therefore, the polymerization was stopped.

[0036]

Comparative Example 2 137.4 g of deionized water and 110.8 g of ammonium sulfate were placed in a four-necked 500 ml separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube.
g, sodium sulfate 25.6 g, 2-acrylamide 2
-Methylpropanesulfonic acid 16.6 g, 60% acrylic acid: 28.8 g, 50% acrylamide: 181.8 g
7 g was added, and 16 mol% of the anionic monomer was neutralized with 6.8 g of 30 wt% sodium hydroxide. Also 15
After neutralizing 90 mol% of the acid with a monomer mixture aqueous solution of methacrylic acid / acrylamide 2-methylpropanesulfonic acid = 3/7 (molar ratio) by weight%, a copolymer aqueous solution produced by polymerization was prepared ( Solution viscosity 42, 600 mPa.
s) 25.0 g were added. Thereafter, nitrogen is introduced from a nitrogen introduction tube while stirring to remove dissolved oxygen. During this time, the internal temperature is adjusted to 25 ° C. by a constant temperature water bath. 30 minutes after the introduction of nitrogen, 1.0% by weight of 2,2-azobis [2- (5
-Methyl-2-imidazolin-2-yl) propane] aqueous solution (3.1 g, relative to monomer, 25 ppm) was added to initiate polymerization. About two hours after the addition, the polymerization did not start.

[0037]

[Table 1] AMP: 2-acrylamide 2-methylpropanesulfonic acid AAC: acrylic acid, AAM: acrylamide, monomer ratio is mol%, dispersion viscosity: mPa · s weight average molecular weight: unit is 10,000

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4D015 BA06 BA10 BA17 DB09 DB30 DC03 DC08 4G065 AB38Y BB06 CA02 DA10 EA01 4J011 HA02 HB14 HB16 HB28 4J100 AB07Q AB07R AG04S AJ02Q AJ08Q AJ09Q AK03PAM09P01 BA53R CA05 CA06 DA38 EA06 FA03 FA19 JA18

Claims (10)

[Claims] 1. A sulfonic acid group-containing monomer represented by the following general formula (1): 1 to 30 mol%, a carboxyl group-containing monomer represented by the following general formula (2): 5 to 50 mol%,
A water-soluble monomer mixture containing 20 to 94 mol% of (meth) acrylamide and 0 to 20 mol% of another copolymerizable nonionic monomer is dissolved in a salt aqueous solution to a high solubility in the salt aqueous solution. An anionic water-soluble polymer dispersion composed of polymer fine particles having a particle size of 100 μm or less produced by a dispersion polymerization method in which a molecular dispersant coexists. Embedded image R1 is hydrogen or methyl group, A is SO3, C6H4SO
3, CONHC (CH3) 2CH2SO3, CONHC
2H4SO3 or COOC2H4SO3, X is a cation R2 is hydrogen, methyl or carboxymethyl, R3
Is hydrogen or carboxyl group, A is COO or C6H
4COO, Y is a cation 2. The anionic water-soluble polymer dispersion according to claim 1, wherein the polymer dispersant is anionic. 3. An ion equivalent of the polymer dispersant is 1.5.
The anionic water-soluble polymer dispersion according to claim 2, wherein the dispersion is from 15 to 15 meq / g. 4. The weight average molecular weight of the anionic water-soluble polymer constituting the anionic water-soluble polymer dispersion is 200.
The anionic water-soluble polymer dispersion according to claim 1, wherein the dispersion is from 10,000 to 20,000,000. 5. The anionic water-soluble polymer dispersion according to claim 1, wherein the salt constituting the aqueous salt solution contains at least one polyvalent anion salt. 6. A sulfonic acid group-containing monomer represented by the following general formula (1): 1 to 30 mol%, (meth) acrylic acid 5 to 50 mol%, (meth) acrylamide 20 to 94 mol%, and copolymerization Dispersion polymerization of a water-soluble monomer mixture containing 0 to 20 mol% of other possible nonionic monomers in a salt aqueous solution in the presence of a polymer dispersant soluble in the salt aqueous solution. A method for producing an anionic water-soluble polymer dispersion composed of polymer fine particles having a particle size of 100 μm or less. 7. When the water-soluble monomer mixture is produced by a dispersion polymerization method in which a possible ionic polymer dispersant coexists in a salt aqueous solution in a salt aqueous solution, the polymerization is started with a redox catalyst. The method for producing the anionic water-soluble polymer dispersion according to claim 6, wherein 8. The method for producing an anionic water-soluble polymer dispersion according to claim 6, wherein the polymer dispersant is anionic. 9. The polymer dispersant has an ion equivalent of 1.5.
The method for producing an anionic water-soluble polymer dispersion according to claim 8, wherein the dispersion is from 15 to 15 meq / g. 10. The method for producing an anionic water-soluble polymer dispersion according to claim 6, wherein the salt constituting the salt aqueous solution contains at least one kind of polyvalent anion salt.