JPH10251530A - High-speed water-absorbing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition high in water-absorbing rate both under pressure and no pressure and great in water-absorbing capacity and low in water-soluble component content, thus applicable to the medical supplies area, etc., by including an expanded water-absorbing resin and an organometallic surfactant. SOLUTION: This composition comprises (A) 100 pts.wt. of an expanded water-absorbing resin and (B) pref. 0.0001-30 pts.wt. of an organometallic surfactant. The component A is prepared, pref. by solution polymerization of a mixture of water-soluble unsaturated monomer and cross-linkable monomer. It is preferable that this composition is 0.02-1.0m<2> /g in specific surface area and a powdery material having an average particle size of 100-1,000μm. Thereby, the objective composition favorably applicable to various uses requiring water absorption and water retention can be afforded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high water absorption rate water absorbing resin composition. More specifically, the present invention relates to a water-absorbent resin composition that has a high absorption rate under no pressure and under pressure, is easy to dry, and has a small load during pulverization.

[0002]

2. Description of the Related Art In recent years, water-absorbent resins have been developed which absorb water tens to hundreds of times as much as their own weight. Various water-absorbing resins have been used for applications requiring water absorption and water retention, such as in the field, industrial fields such as dew condensation prevention and cooling materials.

[0003] As such a water-absorbing resin, for example,
Hydrolyzate of starch-acrylonitrile graft polymer (JP-B-49-43395) and neutralized product of starch-acrylic acid graft polymer (JP-A-51-125468)
No.), saponified vinyl acetate-acrylate copolymer (JP-A-52-14689), hydrolyzate of acrylonitrile copolymer or acrylamide copolymer (JP-B-53-15959), or a mixture thereof. Cross-linked product, self-cross-linked sodium polyacrylate obtained by reverse phase suspension polymerization (JP-A-53-46389), cross-linked polyacrylic acid partially neutralized product (JP-A-55-84304)
No.) etc. are known.

The performance required of the water-absorbent resin differs depending on the application to be used, but the desired properties of the water-absorbent resin for sanitary materials include an absorption capacity under high pressure when in contact with an aqueous liquid. , Fast absorption rate, large liquid permeability and the like. However, the relationship between these properties does not always show a positive correlation, and it has been difficult to improve these properties at the same time.

[0005] As an attempt to increase the absorption rate of a water-absorbing resin, for example, in order to increase the surface area, an attempt has been made to reduce the particle size, granulate or scaly. However, in general, when the water-absorbent resin is formed to have a small particle size, the water-absorbent resin particles form so-called "mamako" upon contact with the aqueous liquid, and the absorption rate is reduced. When the water-absorbent resin is formed in the granulated material, a phenomenon occurs in which the granulated material itself changes into a “mamako” state by contact with the aqueous liquid, and the absorption rate is rather reduced. When the water-absorbent resin is formed into flakes, the absorption rate is improved, but the absorption rate is not sufficient to induce gel blocking. The resulting water-absorbent resins are necessarily bulky and uneconomical because they require larger transportation and storage facilities.

Further, a technique has been proposed in which molecular chains near the surface of the water-absorbent resin are cross-linked to increase the cross-linking density of the surface layer, thereby preventing generation of mamako and improving the absorption rate. Such a technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-44627.
No., JP-A-58-42602, JP-B-60-1869.
0, JP-A-58-180233, JP-A-59-62
665 and JP-A-61-16903. These techniques have provided some improvement in absorption rates. However, these water-absorbent resins actually contain a considerable proportion of fine powder finer than the desired optimum particle size. Therefore, even when such a water-absorbent resin is used, a sufficient absorption rate cannot be obtained, and a decrease in liquid permeability due to gel blocking occurs.

However, these water-absorbing resins have insufficient water absorption rates under no pressure and under pressure, are difficult to dry, and have a large load during pulverization.
In addition, there is a problem that the pore size is not uniform and the water-soluble component of the water-absorbent resin is large.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a water absorbing resin composition having a high water absorption rate.

Another object of the present invention is to provide a water-absorbent resin composition which has a high water absorption rate under no pressure and under pressure, is easy to dry, and has a small load during pulverization.

Still another object of the present invention is to provide a water-absorbing resin composition having a large water absorption and a small water-soluble component of the water-absorbing resin.

[0011]

The above object is achieved by the following (1).
(5) is achieved.

(1) A high water absorption rate water absorbing resin composition containing a foamed water absorbing resin and an organometallic surfactant.

(2) The high water absorption rate water absorbent resin composition according to the above (1), wherein the amount of the organometallic surfactant per 100 parts by weight of the water absorbent resin is 0.0001 to 30 parts by weight.

(3) The water-absorbing resin composition has a composition of 0.02 to
The high water absorption rate water absorbent resin composition according to the above (1) or (2), having a specific surface area of 1.0 m ² / g.

(4) The water-absorbent resin composition is 100 to 1
The high water absorption rate water absorbent resin composition according to the above (3), which is a powder having an average particle diameter of 000 μm.

(5) A high water absorption rate water absorbent resin composition obtained by further treating the water absorbent resin composition according to any one of the above (1) to (4) with a surface crosslinking agent.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a high water absorption rate water absorbing resin composition containing a foamed water absorbing resin and an organometallic surfactant. The foamed water-absorbent resin is obtained by polymerizing a mixture of a water-soluble unsaturated monomer and a crosslinkable monomer in a state in which bubbles of an inert gas are dispersed, or in a state containing a foaming agent, It is obtained by a method such as adding a foaming agent after polymerization. These methods can be used in combination. Examples of the polymerization method of the mixture of the water-soluble unsaturated monomer and the crosslinkable monomer include aqueous solution polymerization, reverse phase suspension polymerization, and emulsion polymerization. Among them, aqueous solution polymerization is preferred.

Examples of the water-soluble unsaturated monomer used in the present invention include (meth) acrylic acid, (anhydride) maleic acid, fumaric acid, crotonic acid, itaconic acid and 2- (meth) acid.
Acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid,
Anionic monomers such as styrenesulfonic acid and salts thereof;
(Meth) acrylamide, N-substituted (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2
Nonionic hydrophilic group-containing monomers such as -hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, N-vinylpyrrolidone, and N-vinylacetamide; N, N-dimethylamino Specific examples include amino group-containing unsaturated monomers such as ethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, and quaternized products thereof. Can be listed. In addition, in an amount that does not extremely impair the hydrophilicity of the obtained polymer, for example, acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, vinyl acetate, and propionic acid A hydrophobic monomer such as vinyl may be used. One or more of these can be selected and used as the monomer component. However, considering the water absorption properties of the finally obtained water absorbing material, (meth) acrylic acid (salt),
2- (meth) acryloylethanesulfonic acid (salt), 2
Selected from the group consisting of-(meth) acrylamide-2-methylpropanesulfonic acid (salt), (meth) acrylamide, methoxypolyethylene glycol (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate or a quaternized product thereof. Preferably, one or more of these are included, and more preferably those containing (meth) acrylic acid (salt) as an essential component. In this case, (meth) acrylic acid 3
Most preferably, 0 to 90 mol% is neutralized with a basic substance.

Examples of the crosslinkable monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate.
Acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate,
Pentaerythritol tetra (meth) acrylate,
There are two ethylenically unsaturated groups in one molecule such as N, N'-methylenebis (meth) acrylamide, triallyl isocyanurate, trimethylolpropanedi (meth) allyl ether, triallylamine, tetraallyloxyethane, glycerolpropoxytriacrylate and the like. Compounds having at least one compound; ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,
4-butanediol, 1,5-pentanediol, 1,
Polyhydric alcohols such as 6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbit, sorbitan, glucose, mannitol, mannitol, sucrose, glucose; ethylene glycol diglycidyl ether; Polyglycidyl ethers such as polyethylene glycol diglycidyl ether and glycerin triglycidyl ether; haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyamines such as ethylenediamine; Calcium, calcium chloride, calcium carbonate, calcium oxide, magnesium borax,
Hydroxides, halides, carbonates, oxides, borates such as borax, metals such as magnesium oxide, aluminum chloride, zinc chloride, nickel chloride, etc. And one or more of these can be used in consideration of reactivity. However, a compound having two or more ethylenically unsaturated groups in one molecule may be used. Most preferably, it is used as a crosslinking agent.

The ratio of the crosslinking monomer used in the present invention is 0.00 0.00 parts by weight per 100 parts by weight of the water-soluble unsaturated monomer.
It is 1 to 2 parts by weight, preferably 0.005 to 1 part by weight. That is, when the amount is less than 0.001 part by weight, the ratio of the water-soluble component in the obtained water-absorbent resin composition becomes large, so that the amount of water absorption under sufficient pressure may not be maintained. In such a case, the crosslinking density becomes too high, and the water absorption of the resulting water-absorbent resin may be insufficient.

In the method of the present invention, when a water-soluble unsaturated monomer and a crosslinkable monomer are copolymerized in an aqueous solution, the total amount of the water-soluble unsaturated monomer and the crosslinkable monomer is based on water. The concentration is not particularly limited as long as the water-soluble unsaturated monomer is dissolved substantially uniformly, but is generally 15 to 50% by weight, preferably 25 to 40% by weight.

In the aqueous solution copolymerization of the water-soluble unsaturated monomer and the crosslinkable monomer, any of continuous polymerization and batch polymerization may be employed. It may be carried out under any normal pressure. The polymerization is preferably performed under a stream of an inert gas such as nitrogen, helium, argon, or carbon dioxide.

In the case of carrying out aqueous solution polymerization, it is more preferable to previously dissolve or disperse the radical polymerization initiator in the aqueous monomer solution. Specific examples of the radical polymerization initiator include, for example, an azo compound represented by 2,2'-azobis (2-amidinopropane) dihydrochloride;
Peroxides such as ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, di-t-butyl peroxide; the above peroxides, sulfites, bisulfites, Redox initiators in combination with a reducing agent such as thiosulfate, formamidinesulfinic acid, ascorbic acid, and the like are included. These radical polymerization initiators may be used alone or in combination of two or more.

The amount of the radical polymerization initiator to be used based on the total amount of the water-soluble unsaturated monomer and the crosslinkable monomer depends on the combination of the monomer and the radical polymerization initiator. It is preferably in the range of 0.001 to 5 parts by weight, more preferably in the range of 0.01 to 1 part by weight, based on 100 parts by weight of the total amount of the unsaturated monomer and the crosslinkable monomer. When the use amount of the radical polymerization initiator is less than 0.001 part by weight, the amount of unreacted unsaturated monomers increases, and therefore, the amount of residual monomers in the obtained water-absorbing resin increases, which is preferable. Absent. On the other hand, if the amount of the radical polymerization initiator exceeds 5 parts by weight, the amount of water-soluble components in the obtained water-absorbing resin increases, which is not preferable.

The temperature at the start of the polymerization depends on the kind of the radical polymerization initiator used, but is preferably in the range of 0 to 50 ° C, more preferably in the range of 10 to 40 ° C. The polymerization temperature during the reaction depends on the type of radical polymerization initiator used, but is preferably in the range of 20 to 110 ° C, and more preferably in the range of 30 to 90 ° C. When the temperature at the start of polymerization or the polymerization temperature during the reaction is out of the above range, (a) the amount of residual monomers in the obtained water-absorbent resin increases, and (b) when foaming with a foaming agent is performed,
There is a possibility that such control becomes difficult, and (c) excessive self-crosslinking reaction proceeds to cause inconveniences such as a decrease in water absorption of the water absorbent resin.

The reaction time may be set according to the combination of the unsaturated monomer, the crosslinking agent, the radical polymerization initiator, or the reaction conditions such as the reaction temperature, and is not particularly limited.

The aqueous solution copolymerization according to the present invention can be carried out in a state where bubbles of an inert gas are dispersed in an aqueous monomer solution in order to foam the resulting water-absorbent resin. And the volume of the monomer aqueous solution in which the inert gas bubbles are dispersed at that time is 1.02 times or more, preferably 1.08 times or more, more preferably 1.11 times or more of the volume of the non-dispersed state,
Most preferably, it is 1.2 times or more.

As a method of dispersing bubbles of the inert gas in the aqueous monomer solution, a method of introducing the inert gas into the aqueous solution, a method of rapidly stirring the aqueous solution at a high speed, a method of adding a foaming agent in advance, and the like. There is a method of combining two or more of the methods.

The above polymerization can be carried out in the presence of a surfactant. By using the surfactant, bubbles of the inert gas can be stably dispersed in the aqueous monomer solution. Examples of such a surfactant include the following.

Examples of the anionic surfactant include fatty acid salts such as mixed fatty acid sodium soap, semi-hardened tallow fatty acid sodium soap, sodium stearate soap, potassium oleate soap and castor oil potassium soap; sodium lauryl sulfate, higher alcohol sodium sulfate Alkylsulfonates such as sodium, sodium lauryl sulfate and triethanolamine lauryl sulfate; alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate; alkylnaphthalenesulfonates such as sodium alkylnaphthalenesulfonate; alkylsulfosuccinates such as sodium dialkylsulfosuccinate Acid salts; alkyl diphenyl ether disulfonates such as sodium alkyl diphenyl ether disulfonate; alkyls such as potassium alkyl phosphate Polyoxyethylene alkyl (or alkylallyl) sulfuric acid such as sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate Ester salt; special reaction type anionic surfactant; special carboxylic acid type surfactant; sodium salt of β-naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate such as sodium salt of special aromatic sulfonic acid formalin condensate A special polycarboxylic acid type polymer surfactant; and polyoxyethylene alkyl phosphate.

Examples of the nonionic surfactant include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether,
Polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether and polyoxyethylene higher alcohol ether, polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether; polyoxyethylene derivatives; sorbitan monolaurate, sorbitan monopalmitate; Sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, sorbitan distearate, and other sorbitan fatty acid esters; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, Polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene Ren sorbitan tristearate,
Polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate and polyoxyethylene sorbitan trioleate; polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbite tetraoleate; glycerol monostearate, glycerol monooleate, self Glycerin fatty acid esters such as emulsified glycerol monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate; polyoxyethylene alkylamine; poly Oxyethylene hydrogenated castor oil; alkyl alkanolamides and the like.

Examples of the cationic surfactant and the double-sided surfactant include alkylamine salts such as coconutamine acetate and stearylamine acetate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, and distearyldimethylammonium. Quaternary ammonium salts such as chloride and alkylbenzyldimethylammonium chloride; alkyl betaines such as lauryl betaine, stearyl betaine and lauryl carboxymethyl hydroxyethyl imidazolinium betaine; and amine oxides such as lauryl dimethylamine oxide.

Further, examples of the surfactant include a fluorinated surfactant and an organometallic surfactant. Among these, there are various types of fluorine-based surfactants, for example, a perfluoroalkyl group obtained by replacing hydrogen of a lipophilic group of a general surfactant with fluorine, and the surface activity is remarkably strong. Is what it is.

When the hydrophilic group of the fluorinated surfactant is changed,
4 types of anionic, nonionic, cationic and amphoteric
Although there are types, a fluorocarbon chain having the same structure is often used for the hydrophobic group. Moreover, the carbon chain which is a hydrophobic group can be used whether it is linear or branched. The following are typical fluorine-based surfactants.

Fluoroalkyl (C ₂ -C ₁₀ ) carboxylic acid, disodium N-perfluorooctanesulfonylglutamate, 3- [fluoroalkyl (C ₆ -C ₁₁ )
Oxy] -1-alkyl (C ₃ ~C ₄₎ sodium sulfonate, 3- [.omega.-fluoroalkanoyl (C ₆ ~
C ₈₎ -N- ethylamino] -1-sodium sulfonate, N-[3- (perfluorooctane sulfonamide) propyl] -N, N-dimethyl -N- carboxymethylene ammonium betaine, fluoroalkyl (C ₁₁ -C ₂₀₎ carboxylic acids, perfluoroalkyl carboxylic acids (C ₇ ~C _13), perfluorooctane sulfonic acid diethanolamide, perfluoroalkyl (C ₄ ~
C ₁₂₎ sulfonate (Li, K, Na), N-propyl-N-(2-hydroxyethyl) perfluorooctane sulfonamide, perfluoroalkyl (C ₆ -C ₁₀₎
Al Hong amidopropyl trimethyl ammonium salts, perfluoroalkyl (C ₆ -C ₁₀₎ -N- ethylsulfonyl glycine salt (K), phosphate bis (N- perfluorooctylsulfonyl -N- ethylamino ethyl), monoperfluoroalkyl Alkyl (C ₆ -C ₁₆ ) ethyl phosphate, perfluoroalkyl quaternary ammonium iodide (trade name: Florade FC-135, cationic fluorine-based surfactant manufactured by Sumitomo 3M Limited), perfluoroalkyl alkoxylate (product Name Florard F
C-171, a nonionic surfactant manufactured by Sumitomo 3M Ltd.), and potassium perfluoroalkylsulfonic acid (trade names: Florade FC-95 and FC-98, an anionic surfactant manufactured by Sumitomo 3M Limited).

The organometallic surfactant refers to a substance having a metal such as Si, Ti, Sn, Zr, or Ge in the main chain of the molecule, preferably a substance having Si in the main chain of the molecule.
More preferred are siloxane-based surfactants. Use of the organometallic surfactant has advantages such as easy control of the bubble diameter in the aqueous monomer solution and improvement in the dispersion stability of the bubbles.

Representative organometallic surfactants include those represented by the following formulas (1) to (19) (Yoshida, Kondo, Ogaki,
Yamanaka, “New Edition Surfactant Handbook”, Engineering Books (1996), p. 34).

[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

Embedded image The metal contained in the main chain of the organometallic surfactant represented by the above formulas (1) to (19) is Si or Ti
Can be used instead of Sn, Zr, Ge and the like.

These surfactants may be used in a total amount of water-soluble unsaturated monomer and water-soluble crosslinkable monomer of 100%.
0.0001 to 10 parts by weight per part by weight, preferably 0.1 to 10 parts by weight.
0003 to 5 parts by weight. That is, if the amount is less than 0.0001 part by weight, it may not be possible to obtain a sufficient effect of increasing the water absorption rate, whereas if it exceeds 10 parts by weight, the effect corresponding to the added amount may not be obtained. Is uneconomical.

Conventionally, it is known to use a surfactant in aqueous solution polymerization, but such a known technique does not improve the water absorption rate at all.

The foamed water-absorbent resin can also be obtained by polymerizing a mixture of a water-soluble unsaturated monomer and a crosslinking agent in the presence of a foaming agent, or adding a foaming agent after polymerization. For example, a solution containing a carboxylic acid monomer or a water-soluble salt thereof and a crosslinking agent is prepared, a carbonate-based blowing agent and a polymerization initiator are added to the solution to form a carbonated monomer solution, and the solution is polymerized. A method of forming a microporous hydrogel, crushing and drying the microporous hydrogel, and treating the surface with a cross-linking agent to obtain a superabsorbent polymer (Japanese Patent Application Laid-Open Nos. 5-237,378 and 7-37). 18
5,331), a method of producing a microporous water-absorbing resin by polymerizing a water-soluble monomer under dispersion of a volatile organic compound such as toluene (US Pat. No. 5,354,290), A water-insoluble foaming agent is dispersed in a reaction mixture comprising a crosslinking agent and a water-soluble solvent using a surfactant,
Then, a method of producing a superabsorbent resin by foaming and further reacting a monomer and a crosslinking agent (US Pat. No. 5,32
8,935 and 5,338,766), 10
A method for producing a superabsorbent water-absorbent resin by copolymerizing a water-soluble monomer and a crosslinking agent using an azo initiator having a time half-life in the range of 30 to 120 ° C (WO95 / 17)
455) A method of obtaining a water-absorbent resin by copolymerizing a water-soluble monomer and a crosslinking agent in the presence of a foaming agent comprising an acrylate complex of an azo compound (WO96 / 17884)
Etc. can be adopted.

Further, foaming is performed by adding an inert gas to the aqueous solution,
For example, the reaction is performed by introducing an inert gas such as air of nitrogen or carbon dioxide, or by stirring the aqueous solution at high speed and vigorously.
Foaming is also performed by adding a foaming agent to the aqueous solution before polymerization.

Examples of such a foaming agent include sodium carbonate, potassium carbonate, ammonium carbonate, magnesium carbonate, calcium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, magnesium hydrogen carbonate, calcium hydrogen carbonate, zinc carbonate, Examples thereof include carbonates such as barium carbonate, water-soluble azo polymerization initiators such as azobisamidinopropane dihydrochloride, dicarboxylic acids such as malonic acid, and volatile organic solvents such as trichloroethane and trifluoroethane. When a blowing agent is added, the amount used is in the range of 0.0001 to 5 parts by weight per 100 parts by weight of the total amount of the water-soluble unsaturated monomer and the water-soluble crosslinkable monomer,
More preferably, the range of 0.001 to 1 part by weight is appropriate.

The blowing agent can be added in advance before the start of the polymerization. Also, it can be added after the start of the polymerization or during the polymerization. It can also be added after polymerization.

The above-mentioned hydrogel containing cells is crushed into fragments of about 0.1 mm to about 50 mm by a predetermined method during or after the reaction, if necessary. Next, in order to foam the foam more efficiently, the hydrogel containing cells is dried. In addition, foaming with a foaming agent can be performed not at the time of reaction but at the time of drying.

The drying temperature is not particularly limited, but may be, for example, in the range of 100 to 250 ° C., more preferably in the range of 120 to 200 ° C. The drying time is not particularly limited, but is preferably about 10 seconds to 5 hours. Prior to drying, the hydrogel resin may be neutralized, or may be further crushed and fragmented.

As the drying method, heating drying, hot air drying,
Various methods such as reduced-pressure drying, infrared drying, microwave drying, drum dryer drying, azeotropic dehydration with a hydrophobic organic solvent, and high-humidity drying using high-temperature steam can be employed, and are particularly limited. Not something. Of the drying methods exemplified above, hot air drying and microwave drying are more preferred. When microwaves are applied to the hydrogel containing bubbles,
Since the bubbles expand several times to several tens times, it is possible to obtain a water-absorbing resin with a further improved water absorption speed.

When the hydrogel containing bubbles is microwave-dried, the thickness of the crushed hydrogel is preferably 3 mm or more, more preferably 5 mm or more, and more preferably 10 mm or more. More preferred. When the hydrogel is subjected to microwave drying, it is particularly preferable to form the hydrogel into a sheet having the above thickness.

In order to incorporate the organometallic surfactant into the water-absorbing resin composition having a high water absorption rate, for example, (1) the organometallic surfactant may be present during the water-soluble copolymerization reaction of the monomer mixture. . In this case, it is preferable to carry out the polymerization in the presence of an organometallic surfactant in any of the foaming methods, because the organometallic surfactant is uniformly dispersed in the water-absorbing resin by an extremely simple method. In addition, it is a matter of course that an organic metal surfactant and another surfactant may be used in combination.

Further, in order to incorporate the organometallic surfactant into the water-absorbing resin composition having a high water absorption rate, for example, (2) an aqueous solution copolymerization of a monomer mixture is carried out in the absence of the organometallic surfactant. When manufacturing water-absorbent resin fired by
The obtained water-absorbent resin may be dried and pulverized if necessary, then impregnated with a solution of an organometallic surfactant, for example, an aqueous solution or an alcohol solution, and further dried and pulverized as necessary.

Also, the above methods (1) and (2) are used in combination,
The organic metal surfactant is present during the water-soluble copolymerization reaction of the monomer mixture, and the obtained water-absorbent resin is dried and, if necessary, pulverized, and then a solution of the organic metal surfactant, for example, an aqueous solution or an alcohol solution Or the like, and then, if necessary, drying and pulverization. It should be noted that the above-described formulation examples can be applied to the case where reverse phase suspension polymerization or emulsion polymerization other than the aqueous solution polymerization is used.

The content of the organometallic surfactant in the thus obtained high water absorption rate water-absorbent resin composition is such that the amount of the organometallic surfactant per 100 parts by weight of the foamed water-absorbent resin is 0.0001 to 30%. Parts by weight, preferably 0.001 to 1
It is desirably in the range of 0 parts by weight. Content 0.0
If the amount is less than 001 parts by weight, the water absorption rate may not be improved. On the other hand, if it exceeds 30 parts by weight, the effect corresponding to the content may not be obtained or the water absorption capacity may decrease. The organometallic surfactant that can be used in the present invention is the same as the organometallic surfactant described as one of the surfactants that may be allowed to coexist at the time of the above-described water-soluble copolymerization reaction (in such an embodiment). Corresponds to the above compounding method (1)).

By the above-mentioned polymerization, that is, by the above-mentioned production method, the water-absorbing resin composition having a high water absorption rate according to the present invention can be easily obtained at low cost. The above water-absorbent resin composition has an average pore diameter in the range of 10 to 500 μm, more preferably in the range of 20 to 400 μm, and still more preferably 30 to 400 μm.
~ 300 μm, most preferably 40-200 μm
m. The average pore diameter is determined by performing an image analysis of a cross section of the dried water-absorbent resin composition with an electron microscope. That is, a histogram representing the pore size distribution of the water-absorbent resin composition is created by performing image analysis, and the number average of the pore sizes is calculated from the histogram, whereby the average pore size is determined.

The water-absorbing resin composition obtained by the above method is porous with a large number of pores inside and on its surface as shown in FIG. The liquid conducting space required for the transfer of the aqueous liquid into the water-absorbent resin composition is sufficiently ensured.
Therefore, it is excellent in liquid permeability and diffusivity of aqueous liquid,
In addition, the water absorption speed and the water retention ability can be improved by the capillary phenomenon. In addition, since the water-absorbent resin composition of the present invention is porous, even when the shape of the water-absorbent resin composition is particulate, liquid permeability is maintained when the aqueous liquid passes between the particles. can do. If the average pore diameter is smaller than 10 μm, there is a possibility that the liquid permeability and the diffusivity of the aqueous liquid may deteriorate. On the other hand, if the average pore diameter is larger than 500 μm, the water absorption rate may not be sufficiently improved.

The water-absorbent resin composition may be treated with a surface cross-linking agent to form a covalent bond (secondary cross-link), thereby further increasing the cross-link density near the surface. The surface crosslinking agent is not particularly limited as long as it is a compound having a plurality of functional groups capable of forming a covalent bond by reacting with a carboxyl group of the water-absorbing resin composition. By treating the water-absorbent resin composition with a surface cross-linking agent, the liquid-permeability, water-absorption rate, water absorption under pressure, and liquid-permeability of the water-absorbent resin composition are further improved.

As the surface cross-linking agent, specifically, for example, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3
-Propanediol, dipropylene glycol, 2,
3,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerin, polyglycerin,
2-butene-1,4-diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2-
Polyhydric alcohol compounds such as cyclohexanediol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol, sorbitol; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether; Epoxy compounds such as glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and glycidol; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylene Hexamine, polyethylene Polyamine compounds such as imines and polyamide polyamines; haloepoxy compounds such as epichlorohydrin, epibromohydrin and α-methylepichlorohydrin; condensates of the above polyamine compounds with the above haloepoxy compounds; -Tolylene diisocyanate,
A polyvalent isocyanate compound such as hexamethylene diisocyanate; a polyvalent oxazoline compound such as 1,2-ethylenebisoxazoline; a silane coupling agent such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltrimethoxysilane; 3-dioxolan-2
-One, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, -Ethyl-1,3-dioxolan-2-one, 4
-Hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,
3-dioxan-2-one, 4,6-dimethyl-1,3
-Dioxan-2-one, 1,3-dioxoban-2-
Alkylene carbonate compounds such as on; and the like, but are not particularly limited thereto.

Of the above surface crosslinking agents, polyhydric alcohol compounds, epoxy compounds, polyamine compounds, condensates of polyamine compounds and haloepoxy compounds, and alkylene carbonate compounds are more preferable.

These surface cross-linking agents may be used alone or in combination of two or more. When two or more surface crosslinking agents are used in combination, the solubility parameter (S
By combining the first surface cross-linking agent and the second surface cross-linking agent having different P values), a water-absorbing resin composition having even more excellent water-absorbing properties can be obtained. The above-mentioned solubility parameter is a value generally used as a factor indicating the breadth of a compound.

The first surface cross-linking agent is a compound having a solubility parameter of at least 12.5 (cal / cm ³ ) ^{1/2 which} can react with a carboxyl group of the water-absorbing resin composition. Is applicable. The second surface cross-linking agent has a solubility parameter of 12.5 (cal / c) capable of reacting with a carboxyl group of the water-absorbent resin composition.
m ³ ) Less than ^1/2 compound, for example, ethylene glycol diglycidyl ether.

The amount of the surface cross-linking agent used for the water-absorbent resin composition depends on the combination of the water-absorbent resin composition and the surface cross-linking agent, but is preferably 0.01 to 100 parts by weight per 100 parts by weight of the dry water-absorbent resin. It may be in the range of 5 parts by weight, more preferably in the range of 0.05 to 3 parts by weight. By using the surface cross-linking agent within the above range, the water absorbing properties for body fluids (aqueous liquids) such as urine, sweat, menstrual blood, etc. can be further improved. If the amount of the surface cross-linking agent used is less than 0.01 parts by weight, the cross-linking density near the surface of the water-absorbent resin composition can hardly be increased. If the amount of the surface cross-linking agent is more than 5 parts by weight, the surface cross-linking agent becomes excessive, which is uneconomical and may make it difficult to control the cross-linking density to an appropriate value.

The method of treating the water-absorbent resin composition with a surface crosslinking agent is not particularly limited.
For example, a method of mixing a water-absorbent resin composition and a surface cross-linking agent without a solvent, a method of dispersing the water-absorbent resin composition in a hydrophobic solvent such as cyclohexane or pentane, and a method of mixing the surface cross-linking agent, After dissolving or dispersing the surface cross-linking agent in the solvent, a method of spraying or dropping the solution or dispersion onto the water-absorbing resin composition and mixing the solution or the dispersion may be mentioned. The hydrophilic solvent is preferably water or a mixture of water and an organic solvent soluble in water.

Examples of the organic solvent include, for example, methyl alcohol, ethyl alcohol, n
-Propyl alcohol, iso-propyl alcohol,
n-butyl alcohol, iso-butyl alcohol, t
Lower alcohols such as -butyl alcohol; ketones such as acetone; ethers such as dioxane, ethylene oxide (EO) adduct of monohydric alcohol, and tetrahydrofuran; amides such as N, N-dimethylformamide and ε-caprolactam; And sulfoxides such as sulfoxide. These organic solvents may be used alone or in combination of two or more.

The amount of the hydrophilic solvent used for the water-absorbent resin composition and the surface cross-linking agent depends on the combination of the water-absorbent resin composition, the surface cross-linking agent, and the hydrophilic solvent. 200 parts by weight or less per part
It is more preferably in the range of 0.001 to 50 parts by weight, further preferably in the range of 0.1 to 50 parts by weight, and particularly preferably in the range of 0.5 to 20 parts by weight.

When the secondary crosslinking is carried out with the above-mentioned surface crosslinking agent, a heat treatment is carried out, if necessary, depending on the type of the surface crosslinking agent, to crosslink the vicinity of the surface of the water-absorbent resin composition object. By performing the secondary crosslinking, it is possible to obtain a water-absorbent resin composition having excellent absorption capacity under pressure.

The mixing device used for mixing the water-absorbent resin composition and the surface cross-linking agent preferably has a large mixing force in order to uniformly and surely mix the two. As the mixing device, for example, a cylindrical mixer,
Double-wall conical mixer, high-speed stirring mixer, V-shaped mixer, ribbon-type mixer, screw-type mixer, fluidized-type furnace rotary desk-type mixer, air-flow-type mixer, double-arm kneader, internal A mixer, a pulverizing kneader, a rotary mixer, a screw extruder and the like are suitable.

The treatment temperature and the treatment time for treating the water-absorbent resin composition with the surface cross-linking agent are appropriately selected and set according to the combination of the water-absorbent resin composition and the surface cross-linking agent, the desired crosslinking density, and the like. The treatment temperature is not particularly limited, but for example, the treatment temperature is preferably in the range of 0 to 250 ° C.

The above-mentioned water-absorbing resin composition may further be added, if necessary, to a deodorant, a fragrance, various inorganic powders, a foaming agent, a pigment, a dye, a hydrophilic short fiber, a plasticizer, a pressure-sensitive adhesive, a surfactant. Agents, fertilizers, oxidizing agents, reducing agents, water, salts and the like may be added to impart various functions to the water-absorbing resin composition.

Examples of the inorganic powder include substances inert to aqueous liquids and the like, for example, fine particles of various inorganic compounds and fine particles of clay minerals. The inorganic powder preferably has an appropriate affinity for water and is insoluble or hardly soluble in water. Specifically, for example, metal oxides such as silicon dioxide and titanium oxide, silicic acids (salts) such as natural zeolite and synthetic zeolite, kaolin, talc, clay,
Bentonite and the like can be mentioned. Among them, silicon dioxide and silicic acid (salt) are more preferable, and silicon dioxide and silicic acid (salt) having an average particle diameter of 200 μm or less as measured by the Coulter counter method are more preferable.

The amount of the inorganic powder to be used in the water-absorbent resin composition depends on the combination of the water-absorbent resin composition and the inorganic powder, etc., but is preferably 0.1 to 100 parts by weight of the water-absorbent resin composition.
001 to 10 parts by weight, more preferably 0.01 to 10 parts by weight.
It may be within the range of 5 to 5 parts by weight. The method of mixing the water-absorbent resin composition and the inorganic powder is not particularly limited, and for example, a dry blending method, a wet mixing method, or the like can be employed, but a dry blending method is preferred.

The water-absorbent resin composition is compounded (combined) with, for example, a fibrous material such as pulp.
It is an absorbent article.

As absorbent articles, for example, sanitary materials (body fluid absorbent articles) such as disposable diapers, sanitary napkins, incontinence pads, wound protection materials, wound healing materials, etc .; absorbent articles such as urine for pets; Materials for civil engineering and construction such as water retention materials, water stop materials, packing materials, gel blisters, etc .; Food products such as drip absorbents, freshness retention materials, cold insulation materials; oil / water separation materials, dew condensation prevention materials,
Various industrial articles such as coagulants; agricultural and horticultural articles such as water retention materials such as plants and soil; and the like are not particularly limited. In addition, for example, a disposable diaper is formed by laminating a back sheet (back material) made of a liquid-impermeable material, the above-described water-absorbent resin composition, and a top sheet (surface material) made of a liquid-permeable material in this order. And a gather (elastic portion) or a so-called tape fastener or the like is attached to the laminate. Further, the disposable diaper also includes pants with a disposable diaper used when disciplining urination and defecation for infants.

The water-absorbing resin composition thus obtained has a water absorption of 10 to 100 g / g, preferably 20 to 8 g / g.
0 g / g. Further, the specific surface area of the water absorbent resin,
0.02 to 1.0 m ² / g, preferably 0.025 to
0.5 m ² / g.

[0091]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to these Examples. Further,% in Examples and Comparative Examples means% by weight unless otherwise specified, and parts means parts by weight.

The amount of water absorbed, the rate of water absorption, and the amount of water-soluble components of the water-absorbent resin composition were measured by the following methods. In the present invention, the specific surface area of the water-absorbent resin is referred to as “B.
E. FIG. T. The specific surface area was determined by the "one-point method". The measuring device is “Specimen fully automatic specific surface area measuring device 4-sorb U1”
(Made by Yuasa Ionics Co., Ltd.). First, about 5 g of a water-absorbent resin (a particle size range of 600 to 300 μm was previously collected by a sieve and used as a sample) was charged into a microcell (TYPE: QS-4) having an internal capacity of about 13 cm ^3.
00), and the microcell containing the sample was heated to 150 ° C. under a nitrogen gas stream to sufficiently deaerate and dehydrate the sample. Next, the microcell containing the sample was cooled to −200 ° C. in a mixed gas stream composed of helium gas and 0.1% krypton gas, and the mixed gas was adsorbed to the sample until equilibrium was reached. Thereafter, the temperature of the microcell containing the sample was returned to room temperature, the mixed gas was desorbed from the sample, and the specific surface area of the water-absorbent resin was determined from the desorbed amount of the krypton mixed gas. The adsorption-desorption process of the microcell containing the sample was performed three times, and the specific surface area of the water-absorbent resin was determined from the average amount.

(1) Water absorption of the water-absorbent resin composition 0.2 g of the water-absorbent resin composition was placed in a tea bag type bag (6 cm
× 6 cm), the opening was heat-sealed, and then immersed in a 0.9% aqueous sodium chloride solution (physiological saline). After 60 minutes, the tea bag bag is pulled up, and after draining at 250 G for 3 minutes using a centrifuge,
The weight W ₁ (g) of the bag was measured. The same operation was performed without using the water-absorbing resin composition, and the weight W ₀ at that time was measured.
(G) was measured. Then, from these weights W ₁ and W ₀ , the following equation is used: Water absorption (g / g) = (W ₁ −W ₀₎ ) / Weight of water-absorbent resin composition (g).

(2) Water absorption rate of water-absorbing resin composition A water-absorbing resin composition (60 sieves in advance by a sieve) was placed in a bottomed cylindrical polypropylene cup having an inner diameter of 50 mm and a height of 70 mm.
A portion having a particle diameter in the range of 0 μm to 300 μm was collected and used as a sample). Next, 28 g of physiological saline was poured into the cup. Then, the time from when the physiological saline was poured until the physiological saline was completely absorbed by the water-absorbent resin composition and disappeared was measured. The measurement was repeated three times, and the average value was taken as the water absorption rate (second).

(3) Amount of water-soluble component in water-absorbent resin composition 0.5 g of the water-absorbent resin composition was dispersed in 1000 ml of deionized water, stirred for 16 hours, and filtered with a filter paper.
Then, the obtained filtrate was titrated by colloid titration to determine the amount (%) of a water-soluble component in the water-absorbent resin composition.

(Average Particle Diameter of Water Absorbent Resin Composition) The average particle diameter is as follows (850 μm, 600 μm,
(300 μm, 150 μm, 106 μm), the water-absorbent resin composition was sieved and classified, and the residual percentage R was plotted on a logarithmic probability paper, and the particle size corresponding to R = 50% was defined as the average particle size.

Example 1 153 parts of acrylic acid, 37% sodium acrylate 16
A monomer aqueous solution containing 15 parts, 4.1 parts of polyethylene glycol (n = 8) diacrylate, and 710 parts of pure water was prepared. Nitrogen was blown into the aqueous monomer solution to remove dissolved oxygen in the solution, and then 1.5 parts of a siloxane-based surfactant (trade name: SILWET FZ-2162, manufactured by Nippon Unicar Co., Ltd.) was added. Then 5 under nitrogen flow
The mixture was stirred vigorously at 000 rpm at high speed to disperse a large amount of nitrogen bubbles in the aqueous monomer solution. When the nitrogen gas was uniformly dispersed in the monomer aqueous solution and the volume became 1.36 times,
10 parts of a 10% aqueous solution of sodium persulfate and 10 parts of a 10% aqueous solution of sodium hydrogen sulfite are added under high-speed strong stirring, and the polymerization is started immediately, and the polymerization is allowed to stand at 25 to 75 ° C. for 2 hours in a state where bubbles are dispersed. went. The sponge-like hydrogel polymer containing a large amount of air bubbles obtained after the polymerization is treated with 1
Shred from 0mm square to 50mm square, then 16
It was dried in a hot air dryer at 0 ° C. for 1 hour. The average diameter of the bubbles in the sponge-like hydrogel polymer was 101 μm.
The dried product was pulverized with a pulverizer, and the material passed through a sieve having an opening of 850 μm was collected to obtain a water-absorbent resin composition (1) of the present invention having an average particle size of 380 μm. Water absorbent resin composition of the present invention (1)
Has a water absorption amount, water absorption rate, water-soluble component amount and specific surface area of 41.0 g / g, 20 seconds, 8.9% and 0.1%, respectively.
05 m ² / g. As shown in FIG. 1, the water-absorbent resin composition was a foam having a large number of pores inside and on the surface.

Example 2 153 parts of acrylic acid, 37% sodium acrylate 16
A monomer aqueous solution containing 15 parts, 4.1 parts of polyethylene glycol (n = 8) diacrylate, and 710 parts of pure water was prepared. Nitrogen was blown into the aqueous monomer solution to remove dissolved oxygen in the solution, and then 0.075 parts of a siloxane-based surfactant (trade name: SILWET FZ-2162, manufactured by Nippon Unicar Co., Ltd.) was added. Then, the mixture was vigorously stirred at 5,000 rpm under a nitrogen stream at a high speed to disperse a large amount of nitrogen bubbles in the aqueous monomer solution. When the nitrogen gas is uniformly dispersed in the monomer aqueous solution and its volume becomes 1.17 times, a 10% aqueous sodium persulfate solution is
And 10 parts of a 10% aqueous sodium bisulfite solution were added, polymerization was immediately started, and the mixture was allowed to stand still at a temperature of 25 to 75 ° C. for 2 hours in a state where bubbles were dispersed. The sponge-like hydrogel polymer containing a large amount of air bubbles obtained after the polymerization is cut into pieces each having a size of 10 mm square to 50 mm square.
It was dried in a hot air dryer at 60 ° C. for 1 hour. The average diameter of the bubbles in the sponge-like hydrogel polymer was 115 μm. The dried product was pulverized with a pulverizer, and the material passed through a sieve having an opening of 850 μm was collected to obtain a water-absorbent resin composition (2) of the present invention having an average particle size of 425 μm. The water absorption amount, water absorption rate, water soluble component amount and specific surface area of the water absorbent resin composition (2) of the present invention were 42.0 g / g, 29 seconds, 8.6% and 0.04 m ² / g, respectively. .

Example 3 153 parts of acrylic acid, 37% sodium acrylate 16
A monomer aqueous solution containing 15 parts, 4.9 parts of polyethylene glycol (n = 8) diacrylate and 710 parts of pure water was prepared. Nitrogen was blown into the aqueous monomer solution to remove dissolved oxygen in the solution, and then 1.5 parts of a siloxane-based surfactant (trade name: SILWET FZ-2162, manufactured by Nippon Unicar Co., Ltd.) was added. Then 5 under nitrogen flow
The mixture was stirred vigorously at 000 rpm at high speed to disperse a large amount of nitrogen bubbles in the aqueous monomer solution. When the nitrogen gas was uniformly dispersed in the monomer aqueous solution and the volume became 1.44 times,
10 parts of a 10% aqueous sodium persulfate solution and 10 parts of a 0.4% L-ascorbic acid aqueous solution are added under high-speed and strong stirring, and the polymerization is immediately started, and the mixture is allowed to stand for 2 hours at a temperature of 25 to 75 ° C. in a state where bubbles are dispersed. The polymerization was carried out. The sponge-like hydrogel polymer containing a large amount of air bubbles obtained after the polymerization is treated with 1
Shred from 0mm square to 50mm square, then 16
It was dried in a hot air dryer at 0 ° C. for 1 hour. The average diameter of the bubbles in the sponge-like hydrogel polymer was 108 μm.
The dried product was pulverized with a pulverizer, and the material passed through a sieve having an opening of 850 μm was fractionated to obtain a water-absorbent resin composition (3) of the present invention having an average particle size of 310 μm. Water absorbent resin composition of the present invention (3)
Has a water absorption, water absorption rate, water-soluble component amount and specific surface area of 35.0 g / g, 22 seconds, 5.4% and 0.4%, respectively.
05 m ² / g.

Comparative Example 1 153 parts of acrylic acid, 37% sodium acrylate 16
A monomer aqueous solution containing 15 parts, 4.1 parts of polyethylene glycol (n = 8) diacrylate, and 710 parts of pure water was prepared. Nitrogen was blown into the monomer aqueous solution to remove dissolved oxygen in the solution. Then, 10 parts of a 10% aqueous sodium persulfate solution and 0.4% L were stirred while stirring under a nitrogen stream.
-Add 10 parts of ascorbic acid aqueous solution, temperature 25-7
Polymerization was performed at 5 ° C. for 2 hours to obtain a finely divided particulate hydrogel polymer. The dried product is pulverized with a pulverizer and the opening is 850μ.
m were passed through a sieve to obtain a comparative water absorbent resin (1) having an average particle diameter of 430 μm. The water absorption amount, water absorption rate and water-soluble component amount of the comparative water-absorbent resin (1) were each 42.5.
g / g, 118 seconds and 10.5%.

[0101]

According to the present invention, since the present invention is constituted as described above, the water absorption rate under no pressure and under pressure is high, the amount of water absorption is large, and the amount of water-soluble components is small. It can be suitably used for various applications that require water absorption or water retention, such as the field of sanitary materials, etc., the field of agriculture and horticulture, the food field such as keeping freshness, and the industrial field such as dew condensation prevention and cooling materials.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing a foamed state of a water-absorbent resin composition of the present invention obtained in Example 1.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hideyuki Tahara 992, Nishioki, Okihama-shi, Aboshi-ku, Himeji-shi, Hyogo

Claims (4)

[Claims] 1. A high water absorption rate water absorbing resin composition containing a foamed water absorbing resin and an organometallic surfactant. 2. The high water absorption rate water absorbent resin composition according to claim 1, wherein the amount of the organometallic surfactant per 100 parts by weight of the water absorbent resin is 0.0001 to 30 parts by weight. 3. The water-absorbent resin composition has a composition of 0.02 to 1.0.
m and has a specific surface area of ² / g according to claim 1 or 2 superabsorbent speed absorbent resin composition. 4. The water-absorbent resin composition is 100 to 1000.
The high water absorption rate water-absorbing resin composition according to claim 3, which is a powder having an average particle diameter of μm.