JPH0684460B2 - Water-swellable polymer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-swellable polymer composition. More specifically, it relates to a water-swellable polymer composition having a reduced residual monomer content, which is useful as a water absorbent resin.

[Prior Art] Conventionally, as the water-absorbent resin composition, there are a copolymer composition of an acrylate and a cross-linking agent, and a polymer composition in which starch is graft-polymerized with the acrylate and the cross-linking agent.

[Problems to be Solved by the Invention] However, the residual monomer content is not sufficiently reduced in these polymer compositions.

[Means for Solving Problems] The present inventors have arrived at the present invention as a result of extensive studies on a water-swellable polymer composition having a small amount of residual monomers.

That is, the present invention provides a water-swellable polymer obtained by polymerizing a water-soluble monomer with a polysaccharide and / or a crosslinkable monomer in an amount of 0.1 to 1
One or more selected from the group consisting of 00 ppm peroxide and / or azobisisobutyronitrile, azobiscyanovaleric acid and 2,2′-azobis (2-amidinopropane) hydrochloride (hereinafter referred to as azo compound),
And a residual monomer content of 500 ppm or less, which is a water-swellable polymer composition.

As the peroxide contained in the water-swellable polymer composition of the present invention, inorganic peroxides [hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.] and
Examples thereof include organic peroxides such as benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, and di (2-ethoxyethyl) peroxydicarbonate.

Among peroxides and / or azo compounds, preferred are peroxides, more preferred are inorganic peroxides, and particularly preferred is hydrogen peroxide.

In the present invention, the water-soluble monomer contains a water-soluble or hydrophilic monomer, for example, a carboxylic acid group-containing polymerizable monomer, a sulfonic acid group-containing polymerizable monomer, and a phosphoric acid group. Acid group-containing monomers such as polymerizable monomers and salts thereof.

As the polymerizable monomer containing a carboxylic acid group, an unsaturated mono- or polycarboxylic acid [(meth) acrylic acid (refers to acrylic acid and / or methacrylic acid. The same description is used below), ethacrylic acid. , Crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, etc.], and their anhydrides [maleic anhydride, etc.] and the like.

Examples of the polymerizable monomer containing a sulfonic acid group include aliphatic or aromatic vinyl sulfonic acids (vinyl sulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, etc.), (meth) acrylic sulfonic acid [( Examples include sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, and the like, and (meth) acrylamidesulfonic acid [2-acrylamido-2-methylpropanesulfonic acid and the like].

Examples of the polymerizable monomer containing a phosphoric acid group include (meth) acrylic acid hydroxyalkyl phosphoric acid monoester [2-
Hydroxyethyl (meth) acryloyl phosphate,
Phenyl-2-acryloyloxyethyl phosphate and the like].

These acid group-containing monomers may be used alone or in combination of two or more.

Of these, preferred are polymerizable monomers containing a carboxylic acid group or sulfonic acid group, and particularly preferred are polymerizable monomers containing a carboxylic acid group.

Examples of such salts include alkali metal salts (salts such as sodium, potassium and lithium), alkaline earth metal salts (salts such as calcium and magnesium), ammonium salts and amine salts (alkylamine salts such as methylamine and trimethylamine). Alkanolamine salts such as triethanolamine and diethanolamine) and two or more of these. Preferred of these are the sodium and potassium salts.

If desired, other polymerizable monomers may be used together with the acid group-containing monomer or a salt thereof. For example, unsaturated carboxylic acids [monocarboxylic acids such as (meth) acrylic acid; maleic acid, fumaric acid, etc. Polycarboxylic acid] alkyl (C ₁ -C ₁₀ ) ester, aromatic vinyl hydrocarbon [styrene etc.], aliphatic vinyl hydrocarbon [ethylene, propylene, butene etc.], unsaturated nitriles [acrylonitrile etc.], (meth ) Examples include acrylamide.

Polysaccharides include starch and cellulose. Examples of the starch include raw starch such as sweet potato starch, potato starch, wheat starch, corn starch, and rice starch; oxidized starch, dialdehyde starch, alkyl etherified starch, aryl etherified starch, oxyalkylated starch, aminoethyl ether. Modified starch such as modified starch is mentioned.

Examples of the cellulose include cellulose obtained from wood, leaves, stems, skins, seed hairs and the like; processed celluloses such as alkyl etherified cellulose, organic acid esterified cellulose, oxidized cellulose and hydroxyalkyl etherified cellulose.

The crosslinkable monomer includes (1) a compound having two polymerizable double bonds and (2) at least one functional group having at least one polymerizable double bond and reactive with the monomer. The compound which has an individual is mentioned.

Examples of the compound (1) include the following.

Bis (meth) acrylamide: N, N'alkylene ((C ₁ -C ₆₎ bis (meth) acrylamides example N, N'-methylene bisacrylamide.

Di- or polyesters of polyols and unsaturated mono- or polycarboxylic acids: Polyols [ethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol,
Polyoxypropylene glycol, etc.] di- or tri- (meth) acrylic acid ester: unsaturated polyester [obtained by reaction of the above polyols with an unsaturated acid such as maleic acid] and di- or tri- (meth)
Acrylic ester [obtained by reaction of polyepoxide with (meth) acrylic acid] and the like.

Carbamyl ester: Polyisocyanate [tolylene diisocyanate, hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate and NCO group-containing prepolymer (obtained by reaction of the above polyisocyanate with active hydrogen atom-containing compound)] Carbamyl ester obtained by reaction with hydroxyethyl (meth) acrylate.

Di- or polyvinyl compounds: divinylbenzene, divinyltoluene, divinylxylene, divinylether, divinylketone, trivinylbenzene and the like.

Di- or poly- (meth) allyl ether of polyols: polyols [alkylene glycol, glycerin, polyalkylene glycol, polyalkylene polyol,
Carbohydrates and the like] di- or poly- (meth) allyl ethers such as polyethylene glycol diallyl ether and allylated starch, allylated cellulose.

Di- or poly-allyl esters of polycarboxylic acids: diallyl phthalate, diallyl adipate and the like.

Esters of unsaturated mono- or poly-carboxylic acids with mono (meth) allyl ethers of polyols: (meth) polyethylene glycol monoallyl ethers
Acrylic ester etc.

Poly (meth) allyloxyalkanes: Tetraallyloxyethane, diaryloxyethane, triaryloxyethane, tetraallyloxypropane, tetraallyloxybutane, tetrametallyloxyethane and the like.

Examples of the compound (2) include (meth) acrylic acid and /
Or an ethylenically unsaturated compound containing a group reactive with another copolymerizable monomer, such as a carboxyl group or a group reactive with a carboxylic acid anhydride group (hydroxyl group, epoxy group, cationic group, etc.). . Specifically, a nonionic group-containing unsaturated compound such as a hydroxyl group-containing unsaturated compound [N-methylol (meth) acrylamide] and an epoxy group-containing unsaturated compound [glycidyl (meth) acrylate] and a cationic group-containing unsaturated compound. Saturated compounds such as unsaturated compounds containing quaternary ammonium base [N, N, N-trimethyl-N- (meth) acryloyloxyethyltrimethylammonium chloride, N,
N, N-triethyl-N- (meth) acryloyloxyethylammonium chloride, etc.], and a tertiary amino group-containing unsaturated compound [dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc.] can give.

Among the crosslinkable monomers, preferred are bis (meth) acrylamide, di- or poly-esters of polyols and unsaturated monocarboxylic acids, and poly (meth) allyloxyalkanes, and particularly preferred are N. , N'-methylenebisacrylamide, ethylene glycol diacrylate, trimethylolpropane triacrylate and tetraallyloxyethane.

The amount of the crosslinkable monomer is usually 0.001 to 10% based on the total weight of all the polymerizable monomers and the crosslinkable monomer, preferably
It is 0.01 to 5%. When the amount of the crosslinkable monomer is less than 0.001%, the obtained polymer has a low gel strength when absorbing water and becomes a sol. On the other hand, if it exceeds 10%, on the contrary, the gel strength becomes excessive and the absorption capacity decreases.

The amount of the other polymerizable monomer used as necessary is usually 30 based on the total weight of the total polymerizable monomer and the crosslinkable monomer.
% Or less, preferably 10% or less.

The amount of each component is as follows. However,% is% by weight based on the total weight of all the polymerizable monomers, the copolymerizable crosslinking agent and the polysaccharide.

Usually preferably all polymerizable monomers: 50 to 99.999 73 to 99.99 Water soluble monomers: 26 to 99.999 63 to 99.99 Other polymerizable monomers: 0 to 300 to 10 Polysaccharides: 0 to 300 20 Copolymerizable cross-linking agent: 0.001-10 0.01-7 A water-swellable polymer is obtained by polymerizing a water-soluble monomer with a polysaccharide and / or a cross-linkable monomer and optionally other polymerizable monomer. Can be manufactured. The polymerization method may be a conventionally known method, and examples thereof include a method of polymerizing using a radical polymerization catalyst and a usual method of irradiating with radiation, electron beams, ultraviolet rays and the like.

Examples of the form of polymerization include solution polymerization such as aqueous solution polymerization, pearl polymerization, bulk polymerization, and emulsion polymerization. Aqueous solution polymerization and pearl polymerization are preferred.

In the method using a radical polymerization catalyst, this catalyst includes azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid, 2,2'-azobis (2-amidinopropane) hydrochloride, etc.], inorganic peroxides [peroxides Hydrogen, ammonium persulfate, potassium persulfate, sodium persulfate, etc.], organic peroxides [benzoyl peroxide,
Di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, di (2-ethoxyethyl) peroxydicarbonate and the like] and redox catalyst [alkali metal sulfite or bisulfite,
A combination of a reducing agent such as ammonium sulfite, ammonium bisulfite and ascorbic acid and an oxidizing agent such as an alkali metal persulfate, ammonium persulfate and peroxide] and two or more thereof.

The catalyst amount may be the same as usual, and is usually 0.0001 to 5 based on the total weight of all polymerizable monomers and crosslinkable monomers.
%, Preferably 0.0005 to 1%.

The method of polymerizing using this catalyst is not particularly limited, and for example, the temperature can be variously changed depending on the kind of the catalyst used, but is usually 0 to 150 ° C, preferably 10 to 100 ° C.

In the case of aqueous solution polymerization, it may be carried out in the presence of a solvent together with water, if necessary. Examples of the solvent include water, methanol, ethanol, acetone, N, N-dimethylformamide, dimethylsulfoxide, methylethylketone, and a mixture of two or more thereof.

The concentration of the monomer when a solvent is used is not particularly limited, but is usually 10% or more, preferably 15 to 80% by weight. If the concentration is less than 10%, the resulting resin has a low absorptivity.

In the present invention, when the water-swellable polymer is a salt-type group (base), a salt-type monomer may be polymerized, and the acid group in the polymer obtained by polymerizing the acid-type monomer may be intermediate. They may be combined to partially form a base. As the alkaline substance used for neutralization, alkali metal compounds such as alkali metal hydroxides (sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.), alkali metal carbonates (sodium carbonate, sodium bicarbonate, etc.), etc. Can be given.

In the present invention, 50 to 90 mol%, preferably 60 to 80 mol% of the acid groups in the polymer may be converted into a salt by a neutralization reaction with an alkaline substance. When the conversion rate, that is, the degree of neutralization is less than 50 mol%, the obtained gel-like hydropolymer has a high tackiness, which makes it difficult to produce a water-absorbent resin with good workability. If it exceeds 90 mol%, the pH of the obtained polymer becomes high, which poses a problem in terms of safety to human skin.

As a method of neutralizing a polymer with an alkaline substance, when the polymerization is carried out using a solvent, the obtained gel polymer is about 1 cm.
There is a method of adding an aqueous solution of an alkaline substance while chopping it into pieces of ³ or less, and further kneading. Further, in the case of polymerizing without using a solvent, there is a method of once adding a solvent such as water to swell the polymer, and then adding an alkaline substance, or adding an aqueous solution of the alkaline substance to the polymer.

Further, in the production of the polymer, instead of the water-soluble monomer or together with this, a monomer which becomes water-soluble by hydrolysis (such as acrylonitrile) may be polymerized and hydrolyzed.

In the present invention, a polymer having higher gel strength can be produced by further crosslinking with a compound having at least two groups that react with an acid group and / or a base in the polymer.

The compound having at least two groups capable of reacting with an acid group and / or a base in the polymer is a functional group capable of reacting with an acid group and / or a base (epoxy group, hydroxyl group, amino group, isocyanate group, etc.). And a polyvalent metal compound capable of forming an ionic crosslink.

Examples of the compound having a functional group capable of reacting with an acid group and / or a base include polyepoxy or polyglycidyl ether compounds (ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, polyethylene). Examples thereof include glycol diglycidyl ether, bisphenol A-epichlorohydrin type epoxy resin, etc.), polyols (glycerin, ethylene glycol, propylene glycol etc.), and (poly) alkylene polyamines (ethylene diamine etc.).

Examples of the polyvalent metal compound include compounds capable of forming an ionic bridge, for example, alkaline earth metals (calcium, magnesium, etc.), hydroxides, halides, salts (sulfates, carbonates, acetates) of zinc, aluminum, titanium and the like. Etc.), specifically calcium hydroxide, zinc diacetate, aluminum chloride and the like.

Of these, preferred are polyglycidyl ether compounds and polyvalent metal compounds.

The addition amount of these compounds can be variously changed depending on the degree of crosslinking of the polymer by the crosslinkable monomer, but is usually 10% or less, preferably 0.001 to 10% with respect to the total weight of the acid group and the base.
5%.

For crosslinking, a compound having at least two functional groups is added to the polymer and kneaded.

Addition and kneading are carried out by adding an aqueous solution, if necessary, and usually carried out by a kneader such as a kneader, universal mixer, extruder or the like.

The water-swellable polymer composition of the present invention is 0.1 to 100 ppm with respect to the weight of the water-swellable polymer (solid) obtained by polymerizing a water-soluble monomer, a polysaccharide and / or a crosslinkable monomer. , Preferably 0.5 to 50 ppm of peroxide and / or azo compound. If the content is less than 0.1 ppm, the residual monomer does not decrease sufficiently. If it exceeds 100 ppm, the absorption capacity of the polymer composition is lowered. The residual monomer content of the water-swellable polymer composition of the present invention is 500 ppm or less, further 300 ppm or less, particularly
It is 100 ppm or less.

The content of the peroxide and / or azo compound is usually 0.1 to 100 ppm with respect to the weight of the water-swellable polymer (solid),
It is preferably 0.5 to 50 ppm. If the content is less than 0.1 ppm, the residual monomer does not decrease sufficiently. If it exceeds 100 ppm, the absorption capacity of the polymer composition is lowered.

The water-swellable polymer composition of the present invention is a gel-like polymer obtained by polymerizing a water-soluble monomer with a polysaccharide and / or a crosslinkable monomer, and a peroxide in excess of the residual amount of the polymerization catalyst. and/
Alternatively, it can be produced by heating and drying a gel polymer composition containing an azo compound to reduce the residual monomer content to 500 ppm or less.

Examples of the method of incorporating the peroxide and / or azo compound into the water-swellable polymer include a method of incorporating the peroxide during the polymerization and a method of incorporating the compound after the polymerization.

As a method of incorporating during the polymerization, (1) a redox catalyst and / or an azo compound, which is a combination of the water-soluble monomer and the polysaccharide and / or the crosslinkable monomer in the above-mentioned polymerization, is used as an oxidizing agent and a reducing agent. Polymerization using, when using a redox catalyst, a production method of reducing the residual monomer content by heating and drying the gel polymer obtained by polymerizing using an oxidizing agent in an amount of 10 to 1000 times equivalent of the reducing agent. To be

In addition, as a method of containing after polymerization, (2) a gel-like polymer obtained by polymerizing a water-soluble monomer and a polysaccharide and / or a crosslinkable monomer, and a peroxide and / or an azo compound are added. A production method in which the residual monomer content is reduced by adding and mixing and heating and drying is included.

In the method (1), which is contained at the time of polymerization, the oxidizing agent is an inorganic peroxide [hydrogen peroxide, ammonium persulfate,
Potassium persulfate, sodium persulfate, etc.] and organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, di (2-ethoxyethyl) peroxydicarbonate, etc. ] Etc. are mentioned. Among these, preferred are inorganic peroxides, and particularly preferred is hydrogen peroxide.

As a reducing agent, an inorganic salt [ammonium sulfite, ammonium bisulfite, ferrous chloride, ferrous sulfate, cuprous chloride, cuprous sulfate, etc.], ascorbic acid, and the like 2
There are more than one species. Of these, preferred is ascorbic acid.

Conventionally, when using a redox catalyst consisting of a combination of an oxidizing agent and a reducing agent, usually the oxidizing agent and the reducing agent are used in approximately equivalent amounts, but in the present invention, the oxidizing agent is 10 to 1000 times equivalent amount of the reducing agent, preferably 30 to 600. It is characterized by using a double-equivalent amount, which is not common sense. More preferably, 30 to 600 times equivalent amount is used. When the amount is less than 10 times equivalent, the amount of residual monomer in the polymer composition does not sufficiently decrease, and when it exceeds 1000 times equivalent, it is uneconomical.

The amount of the reducing agent used in the present invention is usually 0.0001 to 0 based on the total weight of all the polymerizable monomers and the copolymerizable crosslinking agent.
It is 5%, preferably 0.0005 to 0.1%. If it is less than 0.0001%, polymerization hardly occurs, and if it exceeds 0.5%, the molecular weight does not increase and the absorbency of the composition decreases.

The order of adding the oxidizing agent and the reducing agent includes adding the oxidizing agent and the reducing agent, adding the reducing agent and the oxidizing agent, and simultaneously adding the oxidizing agent and the reducing agent.

Further, if necessary, other radical polymerization catalysts can be used in combination. Other polymerization catalysts may be those conventionally known, for example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid, 2,2'-azobis (2-amidinopropane) hydrochloride, etc.]
And two or more of these. The other radical polymerization catalyst may be added at any stage in the order of adding the oxidizing agent and the reducing agent.

The method of polymerizing using this catalyst is not particularly limited, and for example, the temperature can be variously changed depending on the kind of the catalyst used, but is usually 0 to 150 ° C, preferably 10 to 100 ° C.

The polymerization may be carried out in the presence of a solvent, if necessary. Examples of this solvent include water, methanol, ethanol,
Acetone, N, N-dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone and mixtures of two or more of these can be mentioned. The concentration of the copolymerizable monomer when a solvent is used is not particularly limited, but is usually 10% or more, preferably 15 to 80% by weight. Concentration is 10
If it is less than%, the resulting resin has a low absorptivity.

In the method (2) to be contained after the polymerization, the method (1) is used as the peroxide (inorganic peroxide, organic peroxide, etc.) and / or azo compound added before the gel polymer is dried. The same as those described in the section of the radical polymerization catalyst and a combination of two or more kinds of them are included. Inorganic peroxides and organic peroxides are preferable, and hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate and succinic acid peroxide are particularly preferable.

The addition amount of these peroxides and / or azo compounds is usually 0, based on the weight of the polymer (solid) in the polymer gel.
It is 001 to 5%, preferably 0.01 to 3%. Addition amount is 0.0
If it is less than 01%, the residual monomer does not decrease sufficiently. If it exceeds 5%, the absorbency of the polymer composition is lowered.

The peroxide and / or azo compound is usually added in the form of an aqueous solution or a water dispersion in advance to the gel polymer.

Various methods can be used for mixing, and for example, there is a method of using a mixer such as a kneader, universal mixer, or extruder.

The gel polymer thus obtained is dried by heating. The heating and drying temperature is usually 80 to 250 ° C, preferably 100 to 230 ° C, particularly preferably 120 to 190 ° C. The method of heat drying may be a known method, a method of laminating a gel polymer on a perforated plate, a wire net, a flat plate, or a belt and drying it in batch or continuously with hot air,
In a rotary kiln, a method of introducing a gel polymer together with hot air into a fluidized drying furnace and heating and drying, a method of heating and drying the gel polymer by contacting the surface of a hot plate or a heat roller, and a heating vacuum dryer. Examples thereof include a method of adding a gel polymer and heating and drying under reduced pressure.

In the method (2), the product after drying the gel polymer may contain a peroxide and / or an azo compound.

[Examples] Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto. Parts in the examples are parts by weight.

Example 1 80 parts of sodium acrylate, 20 parts of acrylic acid, 0.1 part of N, N'-methylenebisacrylamide and 400 parts of water were charged in a separable flask made of stainless steel having the content 11 and heated from the outside of the flask while stirring. The temperature of the contents was kept at 40 ° C. After replacing the system with nitrogen, 0.6 part of hydrogen peroxide,
Polymerization was initiated by adding 0.03 part of ascorbic acid and 0.1 part of 2,2'-azobis (2-amidinopropane) hydrochloride. The polymerization was completed in about 1 hour to obtain a gel polymer. The obtained gel polymer was stretched and dried on a drum dryer (0.5 rpm) heated so that the surface temperature was 150 ° C.

The amount of residual monomer and the absorption capacity of the obtained water-swellable polymer composition were measured. (The residual monomer was measured by liquid chromatography) The results are shown in Table 1.

Examples 2-4, Comparative Examples 1-2 A water-swellable polymer composition was obtained in the same manner as in Example 1 except that the type and amount of the redox catalyst added in Example 1 are shown in Table 1.

The results of measuring the amount of residual monomer and the amount of absorption of the obtained composition are also shown in Table 1.

Table 1 also shows the results when a usual amount of redox catalyst was added as a comparative example.

Example 5 80 parts of sodium acrylate, 20 parts of acrylic acid, 0.1 part of N, N'-methylenebisacrylamide and 400 parts of water were charged in a separable flask made of stainless steel of content 11, and heated from the outside of the flask while stirring. The temperature of the contents was kept at 40 ° C. After substituting the system with nitrogen, 0.1 part of 2,2'-azobis (2-amidinopropane) hydrochloride was added to initiate polymerization. The polymerization was completed in about 1 hour to obtain a gel polymer. Take out the gel polymer from the flask, add 0.6 parts of hydrogen peroxide as a peroxide to it,
Stir with a kneader for about 2 minutes. The obtained gel polymer was stretched and dried on a drum dryer (0.5 rpm) heated so that the surface temperature was 150 ° C.

The amount of residual monomer and the absorptivity of the obtained water-swellable polymer dried product were measured (the residual monomer was measured by liquid chromatography).

The results are shown in Table 2.

Examples 6 to 8 and Comparative Example 3 A water-swellable polymer was prepared in the same manner as in Example 5 except that the type and amount of the peroxide added to the gel polymer in Example 5 are shown in Table 2. Obtained.

The results of measuring the residual monomer amount and the absorption amount of the obtained polymer are shown in Table 2 together.

Table 2 also shows, as a comparative example, the results when no peroxide was added to and mixed with the gel polymer.

[Effects of the Invention] According to the present invention, a water-swellable polymer composition having the following effects can be produced.

(1) The composition of the present invention is a polymer composition having a small amount of residual monomers.

With the conventional method, a product having a sufficiently reduced residual monomer amount could not be obtained.

However, according to the present invention, it is possible to obtain a monomer having an extremely small residual monomer amount of 500 ppm or less. When the water-swellable polymer of the present invention contains 0.1 to 100 ppm of a peroxide and / or an azo compound, the peroxide and / or the azo compound act to further reduce the residual monomer with time. Have the effect of

(2) The molecular weight does not decrease.

The composition of the present invention does not reduce the molecular weight. Therefore, a substance having a high absorption amount can be obtained.

The water-swellable polymer composition obtained by the present invention having the above effects is an absorbent material, sanitary materials (paper diapers for children and adults, sanitary napkins, sanitary cotton, bandages, incontinence pads, papers. Use in contact with the human body such as towels)
It is useful for industrial applications such as separating agents for water in oil, other dehydrating or drying agents, water retaining agents for plants and soil, sludge coagulating agents, anti-condensation agents used for interior building materials.

Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location // C08F 4/04 MEG 7242-4J 4/32 MEM 7242-4J 6/00 MFU 7242-4J 220/06 MLR 7242-4J 222/38 MNJ 7242-4J 251/00 MQA 7308-4J

Claims (1)

[Claims] 1. A water-swellable polymer obtained by polymerizing a water-soluble monomer with a polysaccharide and / or a crosslinkable monomer is added in an amount of 0.1 to 100 pp.
m peroxide and / or one or more selected from the group consisting of azobisisobutyronitrile, azobiscyanovaleric acid and 2,2′-azobis (2-amidinopropane) hydrochloride, A water-swellable polymer composition having a residual monomer content of 500 ppm or less.