JPH1160616A - Dispersant for reverse-phase suspension polymerization and production of particulate polymer by using this dispersant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize polymerization in a suspension state stable until the end of reaction, by subjecting a hydrophilic monomer to reversephase suspension polymerization in the presence of a radical polymerization catalyst in a solution obtained by dissolving a specified dispersant for reverse-phase suspension polymerization in an alicyclic or aliphatic hydrocarbon solvent. SOLUTION: A high-molecular compound of the formula (wherein R1 is H or methyl; R2 is an 8-18C alkyl; Y is H, ammonia, or an amine salt; and (m) and (n) are each the number of repeating units comprising a group of monomers and giving a molecular weight of polymer of 1,000 to 500,000), in an amount of at least 7 wt.%, is blended with a sorbitan ester of a fatty acid, having an HLB of 3 to 10 to give a dispersant for reverse-phase suspension polymerization. This dispersant is dissolved in an alicyclic or aliphatic hydrocarbon solvent to give a solution. A hydrophilic monomer is subjected to reverse-phase suspension polymerization in the solution in the presence of a radical polymerization catalyst and, if necessary, a crosslinking agent having at least two double bonds in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersant for reversed-phase suspension polymerization used for producing a granular polymer by subjecting a hydrophilic monomer to reverse-phase suspension polymerization, and the dispersant for reversed-phase suspension polymerization. The present invention relates to a method for producing a granular polymer useful for various applications by reverse phase suspension polymerization using the same.

[0002]

2. Description of the Related Art A high degree of polymerization of an acrylic hydrophilic high molecular weight polymer, a linear type, is used as a thickener, a sizing agent, an adhesive, a patch, an aggregating agent for wastewater, and the like. The crosslinked type is widely used as a superabsorbent polymer in sanitizers, agriculture, horticultural materials, food distribution materials, civil engineering, construction materials, cosmetics, toiletry products, medical fields, electricity, electronic materials, etc. However, in any field, a powdery or granular form is desired from the viewpoints of simplicity during transportation, exhibiting characteristics during use, and maintaining high quality.

Among them, the acrylic super water-absorbing polymer generally has difficulty in salt resistance, and in order to improve this, Japanese Patent Application Laid-Open No. 1-249808 discloses, for example,
Japanese Patent Application Laid-Open No. 4-230250 discloses the use of -acrylamide-2-methylpropanesulfonic acid, for example,
The use of N-vinylacetamide is disclosed in
No. 23304 discloses, for example, the use of N-vinylformamide.

[0004] Polymers using these compounds are also required to be powdery or granular like the acrylic hydrophilic high-molecular polymers described above. The method for producing such an acrylic polymer powder or granular product includes: (1) a method in which acrylic acid or / and its alkali metal salt are polymerized by solution polymerization, and the obtained polymer is powder-dried (hereinafter referred to as powder-drying). (2) A method of precipitating pearl polymerization of acrylic acid or / and its alkali metal salt in an organic solvent (hereinafter referred to as precipitation polymerization method). (3) Inverting acrylic acid or / and its alkali metal salt A method of performing phase suspension polymerization (hereinafter referred to as a reversed phase suspension method) and the like are known.

[0005] Among these known methods, the powder drying method has a problem in productivity because the viscosity of a solution becomes high when an intended product having a high degree of polymerization is to be obtained. It is difficult to increase the amount of residual monomers. On the other hand, the reversed-phase suspension method has a high degree of polymerization, has very little residual monomer, and is easy to extract monomers to reduce the residual monomer. Control of the heat of polymerization reaction is also easy. In addition, when a water-absorbing polymer is used, it is most suitable as a production method because it is easy to control the reaction with a cross-linking agent by post-addition, the production process is simple, and the production efficiency is high.

As such a reversed-phase suspension method, Japanese Patent Publication No.
The inventions described in Japanese Patent Publication No. 10644, Japanese Patent Publication No. 54-30710, and the like are known.
Acrylic acid alone or its partially neutralized salt is converted to a sorbitan monostearate or sorbitan oleate having an HLB value of 3
The polymerization is carried out using the nonionic surfactants of Nos. 6 to 6.

[0007]

However, these reversed-phase suspension methods still have a problem that it is difficult to produce a polymer in a stabilized suspension state until the reaction is completed. Simply improving mechanical operation such as stirring conditions is not enough.

An object of the present invention is to provide an anionic or nonionic hydrophilic polymer by ordinary reaction operations without any need for further improvement in mechanical conditions during the reverse phase suspension polymerization of the acrylic monomer. And a dispersant for reversed-phase suspension polymerization to obtain a stabilized suspension without aggregation and grid formation until the end of the reaction, and a method for producing a granular polymer using this dispersant. is there.

[0009]

Means for Solving the Problems In order to achieve the above object, the dispersant for reversed phase suspension polymerization according to claim 1 of the present invention is a compound represented by the following general formula (2). R ₁ is hydrogen or a methyl group; R ₂ is an alkyl group having 8 to 18 carbon atoms;
Is hydrogen, ammonia, amine salt, m and n are each 1
It is the number of repeating units of a monomer group that gives a polymer molecular weight in the range of 000 to 500,000. ) Is contained in an amount of 70% by weight or more.

[0010]

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On the other hand, in the method for producing a granular polymer according to a fourth aspect of the present invention, the dispersant for reverse-phase suspension polymerization is dissolved in an alicyclic or aliphatic hydrocarbon solvent, and the resulting solution is obtained. The present invention is characterized in that a hydrophilic monomer is subjected to reverse phase suspension polymerization using a radical polymerization catalyst in a product.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer compound used as the dispersant for reversed-phase suspension polymerization of the present invention is a polymer compound containing the component represented by the above-mentioned [Chemical Formula 2]. The compound has a carboxyl group as a hydrophilic group and an alkyl ester group of (meth) acrylate as a lipophilic group.

The polymer molecular weight of the polymer compound represented by the general formula by the repeating unit of the monomer group represented by m and n is as follows:
Each is in the range of 1,000 to 500,000.
Among them, the monomer component of one repeating unit represented by m includes unsaturated carboxylic acids such as acrylic acid, methacrylic acid and itaconic acid and / or ammonium salts and amine salts of the respective unsaturated carboxylic acids. One or more of them.

The monomer components of the other repeating unit represented by n include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, and stearyl (meth) acrylate. And so on.

If the n component has a low glass transition point, beads are likely to be blocked during heating and drying of the slurry after polymerization, so that the n component preferably has a high glass transition point. The combination of / stearyl (meth) acrylate has a high glass transition point. It is particularly recommended because it has good solubility in alicyclic and aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents which are solvents used for the reverse phase suspension polymerization of the present invention.

The amount of the polymer component having the number m of repeating units relative to all the polymer components of the polymer compound is in the range of 10 to 70% by weight.
It is in the range of 30% by weight. When the content of the (meth) acrylic acid as the m component is less than 10% by weight, it does not function as a dispersion stabilizer, and when it exceeds 70% by weight, the solubility in a solvent tends to decrease.

The polymer compound of the present invention sufficiently exerts the dispersing effect of reversed-phase suspension polymerization even when used alone, but other compounds having a dispersing effect can be used in combination. That is, the polymer compound is added to the total amount of the
Non-ionic HLB3 based on the premise that the weight% or more is used.
10 to 10 surfactants such as sorbitan monostearate, sorbitan monolaurate, sorbitan fatty acid esters such as sorbitan monooleate, sucrose fatty acid esters, polyglycerin fatty acid esters, and cellulose derivatives such as cellulose ethers and cellulose esters And the like can be used in combination, whereby the stabilization of the suspended particles and the adjustment of the particle size can be facilitated. Among them, sorbitan fatty acid esters having an HLB of 3 to 10 can be particularly preferably used.

If the amount of the polymer compound is less than 70% by weight based on the total amount of the dispersant for suspension polymerization, the stable dispersion state in the course of the reverse phase suspension polymerization reaction is broken, and a large amount of lumps is generated. Is not preferred.

The production of the polymer compound in the dispersant for reverse phase suspension polymerization of the present invention can be obtained by polymerization using a hydrophobic solvent such as ethyl acetate, butyl acetate, benzene, methyl ethyl ketone, etc. The alicyclic and aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents used in the production of the granular polymer by the reversed-phase suspension polymerization of the present invention, for example, N-pentane, n-hexane, cyclohexane, cyclohexane It is preferable to use octane, benzene, and toluene.

As the polymerization method, these alicyclic and aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents are heated to a predetermined temperature under nitrogen aeration, and the repeating units m, n Is converted to an oily catalyst such as benzoyl peroxide, lauryl peroxide,
It can be obtained by a usual polymerization method using azobisisobutyronitrile, azobisisovaleronitrile and triazobenzene. At that time, if necessary, the carboxylic acid moiety can be obtained by neutralizing with ammonia, isopropylamine, triethanolamine, imidazole or the like.

The method for producing the granular polymer of the present invention using the dispersant for polymerization obtained in the above manner comprises dissolving the dispersant for reverse phase suspension polymerization in an alicyclic or aliphatic hydrocarbon solvent, In a suspension, a hydrophilic monomer is subjected to reverse phase suspension polymerization using a radical polymerization catalyst, and the hydrophilic monomer used is (meth)
Acrylic acid or / and its metal salt, (meth) acrylamide, N-vinylacetamide, 2-acrylamide-
It is selected from the group consisting of 2-methylpropanesulfonic acid and / or a metal salt thereof.

The above-mentioned (meth) acrylic acid and / or its metal salt may be, for example, (meth) acrylic acid alone or (meth) acrylic acid such as sodium hydroxide, ammonium hydroxide or potassium hydroxide. It is a partially neutralized product partially neutralized with an alkali, and the degree of neutralization can be changed as necessary.

One or more of these hydrophilic monomers may be used as a main monomer in a proportion of at least 50% by weight based on the total amount of the monomers, depending on the performance required of the granular polymer. Other selected polymerizable monomers can be used in combination at less than 50% by weight. Further, a crosslinking agent having two or more double bonds in the molecule is added to the hydrophilic monomer in an amount of 0.0001 to 5% by weight.
It can be blended for reverse phase suspension polymerization.

As the crosslinking agent, N '@ methylenebisacrylamide, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate,
Glycerin tri (meth) acrylate, trimethylolpropane triacrylate, divinylbenzene and the like can be mentioned. Further, if necessary, a water-soluble crosslinking agent having two or more functional groups capable of reacting with the functional group of the ethylenically unsaturated monomer, for example, (poly) ethylene glycol diglycidyl ether, (poly) glycerin Diglycidyl ether can be used as a crosslinking agent.

The crosslinked polymer thus obtained is a thickening agent having thixotropic properties, a sanitary material as a water-absorbing resin,
It can be used in agriculture, horticultural materials, civil engineering, building materials, cosmetics, toiletry products, medicinal fields and the like.

The solvent used in the reversed phase suspension polymerization of the present invention is:
It is used to make the polymerization reaction system into a water-in-oil type reverse phase suspension and effectively remove the heat of the polymerization reaction, and may be a hydrophobic and inert solvent, for example, N- Pentane, n-hexane, cyclohexane, cyclooctane, benzene, toluene, trichloroethane, carbon tetrachloride and the like can be mentioned.

Examples of the water-soluble radical catalyst used in the reversed phase suspension polymerization of the present invention include persulfates such as ammonium persulfate, potassium persulfate and sodium persulfate, and 2,2-azobis (2-amidinopropane) dibasic acid. 2,2-azobis [2- (2-imidazolin-2-yl) propane] dibasic acid, 4,4-azobis [2- (4-cyanovaleric acid, 2,2-azobis (2-methylbutanamide) Oxime) azo compounds such as dibasic acid.

Further, when an oily radical catalyst such as benzoyl peroxide, lauryl peroxide, azobisisobutyronitrile, azobisisovaleronitrile, or triazobenzene is used in combination, the polymerization yield may be further improved in some cases.

In order to prevent the linear polymer produced by the reverse phase suspension polymerization of the present invention from forming an insoluble component in an aqueous solution or alcohol, a hypophosphite such as hypophosphorous acid, Potassium hypophosphite, sodium hypophosphite, ammonium formate, thiosalicylic acid, thioglycol and the like are recommended, and the amount of addition is 0.001 to 2 with respect to the total amount of the monomers.
% By weight is optimal.

In the production of the granular polymer by the inverse suspension polymerization of the present invention, an aqueous solution of the hydrophilic monomer having a predetermined composition and a predetermined concentration to which a crosslinking agent or the like is added as necessary is prepared. At this time, the concentration of the aqueous solution can be changed in a wide range, but generally 20 to 80% by weight is preferable. The aqueous solution of the monomer and the polymerization-inactive and hydrophobic solvent are mixed, and the ratio of the mixing amount is as follows:
Solvent = 1: 1 to 1: 4 is preferred.

Separately, a predetermined amount of the dispersant for reversed-phase suspension polymerization of the present invention (combined use of the above-described polymer compound and, if necessary, a nonionic surfactant) is dissolved in an organic solvent, and an inorganic solvent such as nitrogen gas is dissolved. Degas by introducing an active gas, raise the temperature to a predetermined temperature under aeration of an inert gas, a hydrophilic monomer aqueous solution,
A water-soluble radical polymerization catalyst aqueous solution and, if necessary, an oil-based radical polymerization catalyst are gradually added to carry out polymerization.

The polymer after completion of the polymerization is composed of beads in the form of beads swelled with water, and further added with a water-soluble polymerization catalyst, subjected to azeotropic dehydration, and then subjected to solid-liquid separation by decantation. By washing the obtained polymer cake with a polymer-insoluble solvent, residual monomers are removed, and a water-insoluble dispersant can be removed. The swollen bead-shaped particles are, for example, at a temperature of 1
If dried at 20 ° C. or lower, a powdery polymer can be obtained.

The typical mode of production of the granular polymer by the reversed-phase suspension polymerization of the present invention, its utility and main applications are as follows. (1) 50% by weight or more of (meth) acrylamide polymer and less than 50% by weight of (meth) acrylic acid and metal salts thereof, N-vinylacetamide, 2-acrylamido-2-methylpropanesulfonic acid, (meth) acrylic A granular polymer obtained by copolymerization with a hydrophilic monomer selected from dimethylaminoethyl acrylate, 2-hydroxyethyl (meth) acrylate, and the like can be used as an aggregating agent, an adhesive, and the like. When a crosslinking agent having two or more bonds is used in an amount of 0.0001 to 5% by weight based on the monomer, a water-absorbing polymer having excellent salt resistance as a crosslinked granular polymer can be obtained.

(2) 50% by weight or more of N-vinylacetamide polymer and less than 50% by weight of (meth) acrylamide, (meth) acrylic acid and metal salts thereof,
Acrylamide-2-methylpropanesulfonic acid (tert-butylacrylamidesulfonic acid) dimethylaminoethyl (meth) acrylate, 2- (meth) acrylic acid
The granular polymer obtained by copolymerization with a hydrophilic monomer selected from hydroxyethyl or the like is a nonionic monomer in which N-vinylacetamide is not only a water-soluble monomer but also has an alcoholic property. Taking advantage of this feature, it can be used as a granular polymer for various uses such as external preparations, cosmetics, adhesives, etc., and a crosslinking agent having two or more double bonds in the molecule can be used in an amount of 0.0001 to the monomer. ~ 5% by weight
It becomes a water-absorbing polymer with excellent salt resistance as a crosslinked type granular polymer by being used in combination, and is used in various fields such as sanitary materials, agriculture, horticultural materials, civil engineering, building materials, cosmetics, toiletry products, medical fields, etc. Will have.

(3) 50% by weight or more of 2-acrylamido-2-methylpropanesulfonic acid and / or a metal salt thereof, and N-vinylacetamide copolymerizable therewith;
(Meth) acrylic acid and its metal salts, dimethylaminoethyl (meth) acrylate and (meth) acrylic acid 2
-Granular polymer by copolymerization with a hydrophilic monomer such as hydroxyethyl is used to improve fiber dyeing, improve hygroscopicity, prevent stains, permanent press processing, sizing agent, paper pulp related paper strength enhancer, drainage improver , Oil from oil wells,
It can be used as a gas recovery material. When a crosslinking agent having two or more double bonds in the molecule is used in an amount of 0.0001 to 5% by weight with respect to the monomer, a water-absorbing polymer having excellent salt resistance as a crosslinked granular polymer can be obtained. . In particular, a salt-resistant water-absorbing resin whose water absorption capacity does not decrease over time even when it comes into contact with an aqueous liquid containing a polyvalent metal ion.

[0036]

The dispersant for reversed-phase suspension polymerization of the present invention comprises a polymer compound having a predetermined repeating unit in which a carboxyl group is selected as a hydrophilic group and an alkyl ester (meth) acrylate is selected as a lipophilic group, if necessary. And a mixture with a sorbitan fatty acid ester having an HLB of 3 to 10. By using this dispersant in carrying out the reverse phase suspension polymerization of the present invention, the dispersant is added to the hydrophobic solvent / polymer dissolved water interface. Is highly effective in stabilizing both interfaces by regular orientation, which is presumed to be able to stably maintain the dispersion of particles in the reversed-phase suspension polymerization system, thereby efficiently obtaining a high-quality granular polymer. Can be.

[0037]

The present invention will be more specifically described below with reference to examples and comparative examples. <Example 1> First, polymer compounds AD of various dispersants for reversed-phase suspension polymerization were prepared as follows.

[Preparation of Polymer A] 700 g of cyclohexane was placed in a 5-neck 2-liter separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube, and the internal temperature was raised to 75 ° C. The mixture was stirred using a stirring blade. Separately, 210 g of stearyl methacrylate and 90 g of acrylic acid were mixed, and 1.5 g of azobisisobutyronitrile was dissolved as a polymerization initiator. This mixed monomer was divided into two parts under nitrogen gas flow, added to the separable flask at 1 hour intervals, and polymerized at 75 ° C. for 6 hours. The solid content after polymerization (temperature: 150 ° C., drying with hot air for 1 hour) was 29.3%, and the number average molecular weight by GPC was 65,000 (converted to pst).

[Preparation of polymer compound B] In the same manner as above, 700 g of N-hexane was placed in a separable flask, and
The internal temperature was raised to 60 ° C. and the mixture was stirred. Separately, 210 g of lauryl methacrylate and 90 g of methacrylic acid were mixed, and 1.5 g of azobisisobutyronitrile was dissolved as a polymerization initiator. This mixed monomer was divided into two parts under a nitrogen gas stream, added to the separable flask at 1 hour intervals, and polymerized at 65 ° C. for 6 hours. The solid content after polymerization (temperature: 150 ° C., drying with hot air for 1 hour) was 29.8%.
The number average molecular weight by C was 80,000 (pst conversion).

[Preparation of Polymer Compound C] In the same manner as above, 700 g of cyclohexane was placed in a separable flask, the internal temperature was raised to 70 ° C., and the mixture was stirred. Separately, stearyl methacrylate 210 g, methacrylic acid 77 g, 2-
Take 13 g of hydroxyethyl methacrylate, mix and mix azobisisobutyronitrile as a polymerization initiator.
5 g were dissolved. The mixed monomer was divided into two parts under nitrogen gas flow, added to the separable flask at 1 hour intervals, and polymerized at 75 ° C. for 6 hours. Thereafter, 50 g of isopropylamine was added. The solid content after polymerization (temperature 150 ° C., drying with hot air for 1 hour) was 29.2%,
The number average molecular weight by C was 70,000 (pst conversion).

[Preparation of Polymer Compound D] In the same manner as described above, 700 g of cyclohexane was placed in a separable flask, the internal temperature was raised to 75 ° C., and the mixture was stirred. Separately, 150 g of stearyl methacrylate and 150 g of acrylic acid were mixed, and azobisisobutyronitrile was used as a polymerization initiator.
5 g were dissolved. This mixed monomer was divided into two parts under nitrogen gas flow, added to the separable flask at 1 hour intervals, and polymerized at 75 ° C. for 6 hours. The solid content after polymerization (temperature: 150 ° C., drying with hot air for 1 hour) was 29.5%, and the number average molecular weight by GPC was 65,000 (converted to pst). Polymer Compounds A to D Obtained in Example 1
Examples 2 to 1 using a dispersant for reversed phase suspension polymerization comprising
Production of 1 granular polymer was carried out.

Example 2 A mixed solvent of 400 g of N-hexane and 400 g of cyclohexane was put into a separable flask, and 3 g of the polymer compound C prepared in Example 1 was added thereto.
And a solution of a dispersant for reversed-phase suspension polymerization composed of 1 g of sorbitan monostearate was added, and the mixture was stirred at 250 rpm, and nitrogen gas was introduced into the solution to raise the temperature to 65 ° C. Separately, 200 g of acrylic acid and 0.2 g of sodium hypophosphite as a chain transfer agent were mixed, and 100 g of ion-exchanged water and 2,2-azobis [2-
(2-imidazolin-2-yl) propane] dibasic acid
A mixed solution in which 3 g was dissolved and a mixed solution in which 0.06 g of azoisobutyl valeronitrile was mixed with 50 g of cyclohexane were dropped into the separable flask over 2 hours. After completion of the dropwise addition, stirring was continued at a temperature of 65 ° C. for 2 hours. In this polymerization reaction, the dispersion state of the polymerization liquid during the polymerization was good. 50 g of water in the polymer slurry thus obtained was dehydrated by an azeotropic operation with N-hexane and cyclohexane, and after cooling, the solvent was filtered off through a 150 mesh wire mesh. The separated polymer was heated at 80 ° C. for 10 minutes.
After drying for an hour with a hot air dryer, the attached solvent and residual moisture were removed. The yield of this polymer (yield of polymer product based on charged monomer) was 93%. 10 of this polymer
% Aqueous solution viscosity was measured using a BM-type rotational viscometer (temperature 25 ° C, 30r
pm), it was 1,200 cps, and there was no insoluble matter. Further, the content of the residual monomer was determined by liquid chromatography (Hitachi L-60) manufactured by Hitachi, Ltd.
00), Column GL Science ODS Inert
It was 1,200 ppm when measured using sil-2 and a detector UV-210 nm.

Example 3 A separable flask was charged with 800 g of N-hexane and 4 parts of the polymer compound C prepared above.
g of sorbitan monostearate (1 g) was dissolved in a dispersant for reverse phase suspension polymerization, and the mixture was stirred at 250 rpm, and nitrogen gas was introduced into the solution to raise the temperature to 65 ° C. Separately, 200 g of acrylic acid and 0.4 g of pentaerythritol tetraallyl ether were mixed, and 100 g of ion-exchanged water and 2,2-azobis [2-
(2-imidazolin-2-yl) propane] dibasic acid
The mixed solution in which 3 g was dissolved was dropped into the separable flask over 2 hours, and thereafter, the heating and stirring were continued for 2 hours. The water in the polymer was dehydrated in the same manner as in Example 1 and cooled.
The solvent was removed by filtration through a 0 mesh wire mesh. There was almost no formation of lumps and grids in the polymer. The polymer was dried in a hot air drier at a temperature of 80 ° C. for 10 hours, and the particle size was 100 to 5 μm.
00 μg of granules were obtained with a yield of 95%. A 0.5% aqueous solution of this polymer is p
After adjusting the H and measuring the viscosity with a B-type rotational viscometer, the temperature was 5
The solution was 50,000 cps at 20 ° C. and 20 rpm with no insoluble matter. The viscosity of the 0.5% aqueous solution was measured with a B-type rotary viscometer at a temperature of 25 ° C. and 0.5 rpm and 1.0 rpm, and the yield value was calculated by the following equation.
It was a cps thixotropic fluid. Yield value = [(apparent viscosity at 0.5 rpm)-(1.0
apparent viscosity at rpm)] / 100

Example 4 In a separable flask, 800 g of N-hexane and 4 parts of the polymer compound D prepared above were added.
g of sorbitan monostearate (1 g) was dissolved in a dispersant for reverse phase suspension polymerization, and the mixture was stirred at 250 rpm and nitrogen gas was introduced into the solution to raise the temperature to 65 ° C. Separately, 200 g of acrylic acid was added to 200 g of ion-exchanged water, neutralized with 230 g of 48% NaOH while cooling the outside, 0.05 g of sodium hypophosphite hydrate was added, and an aqueous solution of sodium acrylate, 2,2-azobis [2-
(2-imidazolin-2-yl) propane] dibasic acid
After dissolving 05 g, a solution of 100 g of ion-exchanged water was dropped into each of the separable flasks over 2 hours, and thereafter, stirring was continued at a temperature of 65 ° C. for 2 hours. The water in the polymer was dehydrated by the same operation as in the example, and after cooling, the solvent was separated by filtration through a 150-mesh wire net. There was almost no formation of lumps and grids in the polymer. The temperature of the polymer is 100 ° C
For 10 hours in a hot air drier to obtain granules having a particle size of 0.5 to 1 mm, and the yield was 92%. The viscosity of a 0.2% aqueous solution of this polymer measured by a B-type rotational viscometer was as follows:
The solution was 570 cps at 5 ° C. and 30 rpm without any insoluble matter. Further, the viscosity of the 0.5% aqueous solution was measured with a B-type rotational viscometer at a temperature of 25 ° C. and 0.5 rpm and 1.0 rpm, and the yield value was calculated in the same manner as in the previous equation.
It was a cps thixotropic fluid. The residual monomer was 1,500 ppm by the same method as in the example.

<Example 5> Preparation of a solvent in a separable flask, a dispersant for reversed phase suspension polymerization, etc. was carried out in accordance with Example 4, 300 g of ion-exchanged water was added to 200 g of acrylic acid, and the outside was cooled. Meanwhile, 1.5 g of N, N-methylenebisacrylamide and 0.2 g of potassium persulfate were added to an aqueous sodium acrylate solution neutralized with 162 g of 48% NaOH.
g, and then 0.1 g of sodium hypophosphite hydrate as a water-soluble chain transfer agent. These mixed liquids were dropped into the separable flask over 2 hours. After completion of the dropwise addition, the mixture was stirred at a temperature of 65 ° C. for 2 hours. The dispersion state of the polymerization liquid during the polymerization was good. The polymer powder obtained in the same manner as in Example 4 was a powder that was smooth and easily pulverized. Using this powder, the physiological salt absorption capacity was measured by the following measurement method and found to be excellent, 50 g.

<Measurement of physiological salt absorption capacity> 1 g of water absorbent resin
Is a 400 mesh nylon bag (10cm × 10cm)
And immersed in 1 liter of 0.9% physiological saline for 1 hour, withdrawn after 1 hour, drained for 15 minutes, weighed, corrected Planck value, and absorbed 1 g of water-absorbent resin The weight of 0.9% saline was taken as the water absorption.

Example 6 In a separable flask, a dispersant for reversed-phase suspension polymerization comprising 4 g of polymer compound A and 1 g of sorbitan monostearate was dissolved in a mixed solvent of 600 g of N-hexane and 200 g of cyclohexane. , 250
While stirring at rpm, the temperature was raised to 65 ° C. under nitrogen gas introduction. Separately, 200 g of acrylamide was dissolved in 300 g of ion-exchanged water, and sodium hypophosphite hydrate 0.1 g was dissolved.
05 g were added. On the other hand, a mixed solution in which 0.3 g of 2,2-azobis [2- (2-imidazolin-2-yl) propane] dibasic acid was dissolved in 50 g of ion-exchanged water was dropped into each separable flask over 2 hours. After dripping 2
The stirring was continued for a time at a temperature of 65 ° C., but the dispersion state of the polymerization liquid during the polymerization was good. The dried polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder.

<Example 7> Preparation of a solvent in a separable flask, a dispersant for reversed-phase suspension polymerization, etc. was carried out according to Example 6, and 140 g of acrylamide was added to ion-exchanged water 1
Dissolve in 70 g of acrylic acid, add 70 g of water to 70 g of acrylic acid,
The vessel was neutralized with 80 g of 48% NaOH while cooling the outside. 1.5 g of N, N-methylenebisacrylamide and 0.2 g of potassium persulfate, and 0.1 g of sodium hypophosphite hydrate as a water-soluble chain transfer agent were dissolved in the monomer aqueous solution obtained by combining both. This mixed aqueous solution was dropped into the separable flask prepared above over 2 hours. Stirring was continued at a temperature of 65 ° C. for 2 hours after the completion of the dropping, but the dispersion state of the polymerization liquid during the polymerization was good. The dried polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder.

<Example 8> In the same manner as described above, a dispersant for reversed-phase suspension polymerization consisting of 800 g of cyclohexane, 4 g of polymer compound A and 1 g of sorbitan monostearate was dissolved in a separable flask, and the mixture was stirred at 250 rpm. While stirring, the temperature was raised to 65 ° C. under nitrogen gas introduction. N-
200 g of vinylacetamide was dissolved in 100 g of water, and 0.05 g of sodium hypophosphite hydrate was added. on the other hand,
2,2-azobis [2- (2-imidazolin-2-yl) propane] in 50 g of ion-exchanged water in a separable flask
A mixed solution in which 0.3 g of dibasic acid was dissolved was added dropwise over 2 hours. Stirring was continued at a temperature of 65 ° C. for 2 hours after the completion of the dropping, but the dispersion state of the polymerization liquid during the polymerization was good. The dried polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder.

Example 9 Preparation of a solvent in a separable flask, a dispersant for reversed-phase suspension polymerization, etc. was carried out according to Example 8, and 140 g of N-vinylacetamide was dissolved in 70 g of ion-exchanged water. And 60 g of acrylic acid and 6
0 g and 48% NaOH while cooling the outside of the container.
Neutralized with 80 g. 1.5 g of N, N-methylenebisacrylamide and 0.2 g of potassium persulfate, and 0.1 g of sodium hypophosphite hydrate as a water-soluble chain transfer agent were dissolved in the monomer aqueous solution obtained by combining both. This mixed aqueous solution was dropped into the separable flask prepared above over 2 hours. Stirring was continued at a temperature of 65 ° C. for 2 hours after the completion of the dropping, but the dispersion state of the polymerization liquid during the polymerization was good. The dried product of the polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder, and was as good as 90 g in the physiological saline absorption ability test of Example 5.

Example 10 In the same manner as described above, 800 g of cyclohexane, a dispersant for reversed-phase suspension polymerization composed of 4 g of polymer compound B and 1 g of sorbitan monostearate were dissolved in a separable flask and stirred at 250 rpm. In the end, the temperature was raised to 65 ° C. under nitrogen gas introduction. 2-
Acrylamide-2-methylpropanesulfonic acid 200
g was dissolved in 100 g of ion-exchanged water, neutralized with 80 g of 48% NaOH while cooling the outside, and 0.05 g of sodium hypophosphite hydrate was added. On the other hand, 50 g of ion exchange water
A mixture of 0.3 g of 2,2-azobis [2- (2-imidazolin-2-yl) propane] dibasic acid was added dropwise to the separable flask over 2 hours. Stirring was continued at a temperature of 65 ° C. for 2 hours after the completion of the dropping, but the dispersion state of the polymerization liquid during the polymerization was good. The dried polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder.

<Example 11> A solvent in a separable flask, a dispersant for reversed-phase suspension polymerization, and the like were prepared according to Example 8, and 140 g of 2-acrylamido-2-methylpropanesulfonic acid was added thereto. Dissolved in 70 g of exchanged water,
While cooling the outside, neutralize with 56 g of 48% NaOH,
Further, 60 g of water was added to 60 g of acrylic acid, and neutralized with 80 g of 48% NaOH while cooling the outside of the container in the same manner. 1.5 g of N, N-methylenebisacrylamide and 0.1 g of potassium persulfate were added to the combined aqueous monomer solution.
2 g and further 0.1 g of sodium hypophosphite hydrate as a water-soluble chain transfer agent were dissolved. This mixed aqueous solution was dropped into the separable flask prepared above over 2 hours.
Stirring was continued at a temperature of 65 ° C. for 2 hours after the completion of the dropping, but the dispersion state of the polymerization liquid during the polymerization was good. The dried polymer powder obtained in the same manner as in Example 2 was a powder that could be easily pulverized as a smooth powder, and was as good as 80 g in a physiological saline water absorption test.

<Comparative Examples 1 to 10> The amount of sorbitan monostearate used as a dispersant for reversed phase suspension polymerization in Examples 2 to 11 was adjusted to each Example without using the polymer compound of the present invention. Dry polymers of Comparative Examples 1 to 10 were obtained by the same operation and method except that they were used in the same amounts. The operations of Comparative Examples 1 to 10 correspond to Examples 2 to 11, respectively, and the results of Comparative Examples 1 to 10 are shown in Tables 2 and 11, respectively. I put together. [Margins below]

[0054]

[Table 1]

[0055]

[Table 2]

The abbreviations and others in Tables 1 and 2 are as follows. a) SMST; sorbitan monostearate b) Adhesion amount of polymer: It is an adhesion amount of the polymer to the stirring blade of the polymerization reactor. c) Dispersion state: a dispersion state during the polymerization reaction. "None" means that no grid is generated, and "More" means that there are many lumps.

As can be seen from Table 1, by using the polymer compound of the present invention as a dispersant for reversed-phase suspension polymerization, (meth) acrylic acid and / or Various granular forms mainly composed of the metal salt, (meth) acrylamide, N-vinylacetamide, 2-acrylamido-2-methylpropanesulfonic acid and / or a hydrophilic monomer selected from the group consisting of the metal salt. A polymer can be easily obtained,
Moreover, in this polymerization, it is clear that the polymer dispersion is kept in a stable state until the end of the polymerization, and the adhesion of the polymer to the polymerization vessel, the stirrer, etc. is greatly improved, and a high quality polymer is obtained. It is.

[0058]

The dispersant for reversed-phase suspension polymerization of the present invention comprises a polymer compound having a predetermined repeating unit in which a carboxyl group is selected as a hydrophilic group and an alkyl ester (meth) acrylate is selected as a lipophilic group. HLB = 3-10 depending on
And a mixture thereof with a sorbitan fatty acid ester of the present invention. By using this dispersant in carrying out the reversed phase suspension polymerization of the present invention, the dispersant is regularly oriented at the hydrophobic solvent / polymer dissolved water interface. Thus, it is presumed that the effect of stabilizing both interfaces is large, and that this can stably maintain the dispersion of particles in the reversed-phase suspension polymerization system, whereby a high-quality granular polymer can be efficiently obtained.

In the method for producing the granular polymer of the present invention, the use of the dispersant for reversed phase suspension polymerization of the present invention eliminates the instability of the dispersion during the polymerization and stabilizes the dispersion until the end of the polymerization. Reverse phase suspension polymerization is enabled, whereby a high quality granular polymer can be obtained efficiently.

Claims (7)

[Claims] 1. A compound represented by the following general formula (wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkyl group having 8 to 18 carbon atoms, Y is hydrogen, ammonia, an amine salt, m and n is the number of repeating units of a monomer group that gives a polymer molecular weight in the range of 1,000 to 500,000.) Dispersant for polymerization. Embedded image 2. The dispersant for reversed-phase suspension polymerization according to claim 1, wherein the amount of the polymer component having the number m of repeating units relative to the total polymer component of the polymer compound is in the range of 10 to 70% by weight. 3. The reversed-phase suspension according to claim 1, wherein the dispersant for reversed-phase suspension polymerization is a mixture of the polymer compound and a sorbitan fatty acid ester having an HLB of 3 to 10. Dispersant for polymerization. 4. The dispersant for reversed phase suspension polymerization according to claim 1, wherein the dispersant is dissolved in an alicyclic or aliphatic hydrocarbon solvent, and a hydrophilic monomer is dissolved in the resulting solution. A method for producing a granular polymer, comprising performing reverse phase suspension polymerization using a radical polymerization catalyst. 5. The method according to claim 1, wherein the hydrophilic monomer is (meth) acrylic acid or / and a metal salt thereof, (meth) acrylamide,
The method for producing a granular polymer according to claim 4, wherein the monomer is selected from the group consisting of N-vinylacetamide, 2-acrylamido-2-methylpropanesulfonic acid and / or a metal salt thereof. 6. The method according to claim 1, wherein the hydrophilic monomer is (meth) acrylic acid or / and a metal salt thereof, (meth) acrylamide,
At least 50% by weight of one or more monomers selected from the group consisting of N-vinylacetamide, 2-acrylamido-2-methylpropanesulfonic acid and / or a metal salt thereof, and at least 50% by weight; The method for producing a granular polymer according to claim 4, wherein the method comprises a polymerizable other monomer. 7. The method according to claim 7, wherein the hydrophilic monomer has 2
The method for producing a granular polymer according to claim 5, wherein 0.0001 to 5% by weight of a crosslinking agent having two or more double bonds is blended to carry out reverse phase suspension polymerization.