JPH0768301B2 - Salt-resistant water absorbent and method for producing the same - Google Patents

Description

The present invention relates to a salt-resistant water-absorbing agent and a method for producing the same. More particularly, it relates to a salt-resistant water-absorbing agent that does not aggregate during production and use, and a method for producing the same.

(Prior Art) Since a crosslinked polymer containing a sulfonic acid group is excellent in salt resistance, hot water resistance, light resistance, acid resistance, alkali resistance, etc.,
It is used as a sealant for industrial and civil engineering. In these applications, crosslinked polymer fine particles having a particle diameter of 100 μm or less are mixed with various binders such as rubber and plastic. However, the crosslinked sulfonic acid group-containing polymer has a strong hygroscopic property, and particularly in the case of fine particles, there is a problem in that it easily aggregates due to moisture absorption or the like.

For this reason, the fine particles of the cross-linked polymer may not be efficiently produced, or may be aggregated when used for various purposes, which may cause deterioration of product performance.

(Problems to be Solved by the Invention) The present invention solves the above problems.

Therefore, an object of the present invention is to provide a salt-resistant water-absorbing agent excellent in productivity and workability without agglomeration during production of the salt-resistant water-absorbing agent or kneading and dispersion in various binders such as rubber and plastic. It is to be.

(Means and Actions for Solving Problems) In order to solve the above problems, the present invention provides the following general formula (I). (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
A linear or branched alkylene group, X is -NH-
Further, -O- and Y represent hydrogen, an alkali metal, an alkaline earth metal, an ammonium group or an organic substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer 20 to 10
On the surface of crosslinked polymer particles obtained by polymerizing a monomer component consisting of 0 mol% and 0 to 80 mol% of another polymerizable monomer in the presence of a crosslinking agent, a compound of the general formula (II) (R ³ _m SiX) _4-m (II) (wherein R ³ may have a substituent, an alkyl group, an aryl group or an unsaturated aliphatic residue, X is an alkoxy group,
Acyloxy group, hydrogen atom, halogen atom or hydroxyl group,
m represents an integer of 0 or 1 to ^3, and m R ³ and 4-
The m Xs may be different from each other. The present invention provides a salt-resistant water-absorbing agent having a silicon compound represented by the formula (4) and / or a condensate of a dimer to a decamer thereof attached thereto.

In order to solve the above problems, the present invention also provides the following general formula (I): (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
A linear or branched alkylene group, X is -NH-
Further, -O- and Y represent hydrogen, an alkali metal, an alkaline earth metal, an ammonium group or an organic substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer 20 to 10
Water obtained by polymerizing a monomer component consisting of 0 mol% and other polymerizable monomer 0 to 80 mol% in the presence of a cross-linking agent, and in the range of 1 to 200 wt% based on the absolute dry weight. The cross-linked polymer containing the compound of the formula (II) (R ³ _m SiX) _4-m (II) (wherein R ³ may have a substituent, an alkyl group, an aryl group or an unsaturated group) Aliphatic residue, X is an alkoxy group,
Acyloxy group, hydrogen atom, halogen atom or hydroxyl group,
m represents an integer of 0 or 1 to ^3, and m R ³ and 4-
The m Xs may be different from each other. ) Is dispersed in a substantially inert solvent in the silicon compound represented by the formula (1) and / or its 2- to 10-mer, and the polymer compound crosslinked dispersion contains the silicon compound represented by the general formula (II) and / or Alternatively, the 2 to 10 mer thereof is added at a ratio in the range of 0.1 to 100 parts by weight to 100 parts by weight of the crosslinked polymer, and then the silicon compound and / or the 2 to 10 mer thereof is added. By maintaining the molecular crosslinked body dispersion liquid at a temperature of 0 to 200 ° C., the silicon compound and / or 2 to 10 thereof can be obtained.
The present invention provides a method for producing a salt-resistant water-absorbing agent, which comprises subjecting a monomer to a condensation reaction.

The sulfonic acid group-containing unsaturated monomer used in the present invention is
It is represented by the general formula (I), and for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, 3-sulfopropyl (meth) acrylate, 1-sulfopropan-2-yl ( (Meth) acrylate, 2-sulfopropyl (meth) acrylate, 1-sulfobutan-2-yl (meth) acrylate, 2-sulfobutyl (meth) acrylate, 3
-Unsaturated sulfonic acids such as sulfobutan-2-yl (meth) acrylate and their alkali metal salts such as lithium, sodium and potassium, alkaline earth metal salts such as calcium and magnesium, ammonium salts, organic substituted ammonium salts It is possible to use one or two or more of these.

Examples of the other polymerizable monomer that can be used in the present invention include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid, and their alkali metals. Carboxyl group-containing unsaturated monomers such as salts, alkaline earth metal salts, ammonium salts and organic substituted ammonium salts;
(Meth) acrylamide, (meth) acrylonitrile,
Water-soluble unsaturated monomers such as vinyl acetate, N, N-dimethylaminoethyl (meth) acrylate, 2- (methacryloyloxyethyl) trimethylammonium chloride; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene Glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, methoxy polypropylene glycol mono (meth) acrylate, methoxy polybutylene glycol mono (meth) acrylate, ethoxy polyethylene glycol mono (meth) Acrylate,
Ethoxy polypropylene glycol mono (meth) acrylate, ethoxy polybutylene glycol mono (meth)
Acrylate, methoxy polyethylene glycol / polypropylene glycol mono (meth) acrylate, phenoxy polyethylene glycol mono (meth) acrylate, benzyloxy polyethylene glycol mono (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate (Meth) acrylic acid ester such as; and hydrophobic unsaturated monomers such as styrene, vinyl chloride, butadiene, isoprene, ethylene, propylene, and the like, and one or more of these may be used. it can.

In the present invention, it is necessary that the monomer component contains 20 to 100 mol% of a sulfonic acid group-containing unsaturated monomer. If it is less than 20 mol%, the salt resistance of the resulting water absorbing agent will be low, or the water absorption capacity will be low.

In the present invention, in order to obtain a crosslinked polymer, it is necessary to add a crosslinking agent to the monomer component. Examples of these cross-linking agents include divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth).
Acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol di (meth) acrylate, N, N-methylenebisacrylamide, triallyl isocyanurate, trimethylolpropane diallyl ether etc. in one molecule Compounds having two or more ethylenically unsaturated groups; ethylene glycol, diethylene glycol,
Polyethylene alcohols such as triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbit, sorbitan, glucose, mannitol, mannitan, sucrose and glucose. Ethylene glycol diglycidyl ether, glycerin diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane Diglycidyl ether, trimethylolpropane tri Glycidyl ethers, polyepoxy compounds such as glycerol triglycidyl ether and the like, may be used alone or two or more thereof. 150 when using a polyhydric alcohol as a cross-linking agent
℃ ~ 250 ℃, 50 ℃ when using a polyepoxy compound
It is preferable to heat-treat after polymerization at ˜250 ° C. If a cross-linking agent is used, the water absorption capacity of the resulting salt-resistant water absorbing agent can be easily controlled.

The polymerization method for obtaining a crosslinked polymer in the present invention is
Any conventionally known method may be used, and examples thereof include a method using a radical polymerization catalyst and a method of irradiating with radiation, electron beams, ultraviolet rays and the like. As radical polymerization catalysts, peroxides such as hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, azo compounds such as azobisisobutyronitrile, and radical generation of persulfates such as ammonium persulfate and potassium persulfate An agent or a redox initiator obtained by combining these with a reducing agent such as sodium hydrogen sulfite, L-ascorbic acid, and ferrous salt is used. As the polymerization solvent, for example, water, methanol, ethanol, acetone, dimethylformamide, dimethylsulfoxide, hexane, cyclohexane, xylene, toluene, benzene, etc., or a mixture thereof can be used. The temperature at the time of polymerization varies depending on the type of catalyst used, but a relatively low temperature is preferable because the molecular weight of the crosslinked polymer increases. However, in order to complete the polymerization, it is preferably in the range of 20 ° C or higher and 100 ° C or lower.

The concentration of the monomer in the polymerization system is not particularly limited, but it is preferably in the range of 20 to 80% by weight in view of easiness of control of the polymerization reaction, yield and economy. Although various forms can be adopted as the polymerization form, for example, suspension polymerization, cast polymerization, a method of polymerizing while subdividing the gel-like hydropolymer by the shearing force of a double-arm kneader (JP-A-57-34101). Is mentioned. Among these, (reverse phase) suspension polymerization is particularly preferable in that spherical particles can be obtained.

In the present invention, the average particle size of the crosslinked polymer particles to be subjected to the condensation reaction of the specific silicon compound and / or its 2-10 mer on the surface is not particularly limited, but the average particle size is 100.
It is preferably μ or less. If it exceeds 100 μ, it may be difficult to knead and disperse it in various binders such as rubber and plastic. Further, in general, particles having an average particle size of more than 100 μm tend to be less likely to aggregate even if a specific treatment is not performed, so that the treatment effect of the silicon compound in the present invention becomes small.

Silicon compound used in the present invention and / or its 2
To decamers are silicon compounds represented by the general formula (II) and / or dimers to decamers thereof, such as orthomethyl silicates, orthoethyl silicates, orthopropyl silicates and orthobutyl silicates. And their 2- to 10-mers; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane. ,
γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-
Anilinopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ
A silane coupling agent such as mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, β- (3,4epoxycyclohexyl) ethyltrimethoxysilane; methyltrimethoxysilane, methyltriethoxysilane, octadecyltrimethoxysilane, Alkyl or arylalkoxysilanes such as octadecyltriethoxysilane, methyloctadecyldimethoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane; phenyltrichlorosilane, diphenyldichlorosilane, triphenyl Chlorosilane, Methyltrichlorosilane, Methyldichlorosilane, Dimethylchlorosilane, Ethyltrichlorosilane, Propyl Examples thereof include rutrichlorosilane, butyltrichlorosilane, octadecyltrichlorosilane, methyloctadecyldichlorosilane, and dimethyloctadecylchlorosilane, and one or more of these may be used.

The amount of the silicon compound and / or its 2- to 10-mer used is preferably 0.1 to 100 parts by weight based on 100 parts by weight of the crosslinked polymer. If it is less than 0.1 part by weight, the effect of treating the surface of the crosslinked polymer particles may be insufficient, and if it exceeds 100 parts by weight, the water absorption capacity of the salt-resistant water-absorbing agent obtained may decrease.

When the condensation reaction of the silicon compound and / or its 2- to 10-mer is carried out on the surface of the crosslinked polymer particles, water in the range of 1 to 200% by weight based on the absolute dry weight of the polymer crosslinked polymer is crosslinked. It is preferably contained in the body.
If it is less than 1% by weight, the reaction rate becomes very slow, and
If it exceeds 200% by weight, the reaction rate becomes too fast, and the crosslinked polymer may aggregate during the condensation reaction.

When the condensation reaction of the silicon compound and / or its 2- to 10-mer is carried out on the surface of the crosslinked polymer particles, the reaction is carried out in a solvent which is substantially inert to the silicon compound and / or its 2- to 10-mer. It is preferable to carry out. The solvent used is not particularly limited as long as it is not reactive to a silicon compound and / or its 2- to 10-mer, such as water or an aqueous solvent, for example, hexane, octane, cyclohexane, benzene, toluene, xylene, methanol, Ethanol, isopropyl alcohol, dimethyl sulfoxide, dimethylformamide, dimethylacetamide,
Mention may be made of one kind or a mixture of two or more kinds of ethylene dichloride, chloroform, diethyl ether and the like.

When the silicon compound and / or its 2-10 mer is subjected to condensation reaction on the surface of the crosslinked polymer particles, a known condensation reaction catalyst can be added in order to accelerate the reaction rate. The catalyst used is not particularly limited, but examples thereof include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, and organic amines.

In addition, in order to suppress the reaction rate, acetylacetone,
It is also possible to add a chelating agent such as ethylene or glycol.

In the present invention, in order to cause the condensation reaction of the silicon compound and / or its 2- to 10-mer on the surface of the crosslinked polymer particles, the silicon compound and / or its 2 There is no particular limitation as long as it can produce a condensate of 10-mer. However, from the viewpoint that a salt-resistant water-absorbing agent with excellent performance can be easily obtained, a silicon compound and / or its 2- to 10-mer is added to a dispersion liquid of a crosslinked polymer in the solvent, and the mixture is added at 0 to 200 ° C. A method of maintaining the temperature of 0.5 to 6 hours is preferable. If the reaction temperature is lower than 0 ° C, the reaction rate becomes slow, and it is difficult to obtain a salt-resistant water-absorbing agent having excellent performance, and if the temperature exceeds 200 ° C, the particles of the crosslinked polymer easily aggregate during the condensation reaction.

(Effect of the invention) The salt-resistant water-absorbing agent of the present invention has good fluidity because it does not agglomerate at the time of its production or handling work in various applications thereof, and therefore, the original performance of the water-absorbing agent can be sufficiently exhibited, It is also easy to handle. Further, since the salt-resistant water-absorbing agent of the present invention has good dispersibility in various binders such as rubber and plastic, a rubber / plastic molded product or sheet in which it is mixed or applied has a water absorption capacity, a water absorption speed, durability. Is excellent.

Therefore, the salt-resistant water-absorbing agent of the present invention can be used as a waterproofing material for optical / electrical cables, a civil / industrial sealing material, a water-expandable rubber, a gelling agent for a solution, a dehydrating agent for a solvent / oil, an electrorheological fluid, etc. It can be used effectively.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 A 2-liter four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a nitrogen gas introducing tube was charged with 1200 g of cyclohexane, 12 g of sorbitan monostearate was added and dissolved, and then the atmosphere was replaced with nitrogen. On the other hand, 151 g (0.70 mol) of sodium salt of 2-sulfoethyl methacrylate was added to the dropping funnel,
Methacrylic acid 6.5 g (0.075 mol), sodium methacrylate 24.3 g (0.225 mol), N, N-methylenebisacrylamide 0.154 g (0.001 mol), water 268 g and polymerization initiator V-50 (Wako Pure Chemical Industries, Ltd. ) 2,2'azobis (2-
0.2 g of amidinopropane) dihydrochloride) was added and dissolved, and then nitrogen gas was blown into the solution to remove oxygen existing in the aqueous solution. Then, the contents of the dropping funnel were added to the four-necked flask and dispersed therein, and while slightly introducing nitrogen gas, the temperature of the polymerization system was kept at 60 to 65 ° C. by a water bath and the polymerization reaction was continued for 3 hours. It was Then, 232 g of water in the system was distilled off by azeotropic distillation with cyclohexane.

Next, 18 g of orthomethyl silicate was added to the four-necked flask, and the mixture was kept at 70 ° C. for 3 hours while stirring. afterwards,
The solid content of the resulting suspension was dried and dried to obtain the salt-resistant water absorbing agent (1) of the present invention.

The obtained water absorbing agent (1) had a small amount of agglomerates (48 mesh standard sieve non-passed matter, the same hereinafter) as 0.1% and was excellent in fluidity. The average particle size of unaggregated substances (48 mesh standard sieve passed product, the same applies hereinafter) in the water absorbing agent (1) was measured using a Shimadzu laser diffraction type particle size distribution measuring device, and was 13.2μ.
Met.

Comparative Example 1 The same procedure as in Example 1 was carried out until the water in the system was distilled off by azeotropic distillation with cyclohexane, and then the solid was dried and dried to obtain a comparative water absorbing agent (1).

The obtained comparative water-absorbing agent (1) had 5.2% aggregates,
It was inferior in liquidity. The average particle size of the unaggregated substances in the comparative water absorbent (1) was 20.3 μm.

Example 2 229 g (1.0 mol) of sodium 2-acrylamido-2-methylpropanesulfonate, 0.0592 g (0.002 mol) of trimethylolpropane triacrylate, 221 g of water, 0.2 g of ammonium persulfate as a polymerization initiator, and 1200 g of xylene as a dispersion medium. Polymerization was performed in the same manner as in Example 1 except that it was used. Then, the water in the system is removed by azeotropic distillation with xylene.
Distilled out 0 g.

Next, 6.9 g of methyltrimethoxysilane was added to the four-necked flask, and the mixture was kept at 70 ° C. for 3 hours while stirring. Then, the solid content of the obtained suspension was dried and dried to obtain the salt-resistant water-absorbing agent (2) of the present invention.

The obtained water absorbing agent (2) had a small amount of aggregates of 0.3% and was excellent in fluidity. The average particle size of the unaggregated material in the water absorbing agent (2) was 35.6 μm.

Comparative Example 2 The same procedure as in Example 2 was conducted until the end of the polymerization, and then 200 g of water in the system was distilled off by azeotropic distillation with xylene. Then, the solid content was excessively dried and a comparative water absorbing agent (2) was obtained.

The obtained comparative water absorbent (2) had 7.2% of aggregates,
It was inferior in liquidity. The average particle size of the unaggregated substances in the comparative water absorbent (2) was 40.3 μm.

Example 3 Sodium salt of 2-sulfoethyl methacrylate 90.8 g
(0.42 mol), methacrylic acid 4.3 g (0.05 mol), sodium methacrylate 14.0 g (0.13 mol) acrylamide 28.
4 g (0.40 mol), ethylene glycol diglycidyl ether 0.087 g (0.0005 mol), water 200 g, polymerization initiator ammonium persulfate 0.1 g, and n-hexane 10 as a dispersion medium.
Polymerization was performed in the same manner as in Example 1 except that 00 g was used. After that, 180 g of water in the system is azeotroped with n-hexane.
Distilled.

Next, vinyl triethoxysilane (1.5 g) and orthoethyl silicate (9.0 g) were added to a four-necked flask and stirred.
Hold at 70 ° C for 5 hours. Then, the solid content of the obtained suspension was dried and dried to obtain the salt-resistant water-absorbing agent (3) of the present invention.

The obtained water absorbing agent (3) had a small amount of aggregates of 0.1% and was excellent in fluidity. The average particle size of the unaggregated material in the water absorbing agent (3) was 27.3 μm.

Comparative Example 3 The same procedure as in Example 3 was performed until the water in the system was distilled off by azeotropic distillation with n-hexane, and then the solid content was excessively dried to obtain a comparative water absorbing agent (3).

The obtained comparative water-absorbing agent (3) had 8.1% of aggregates,
It was inferior in liquidity.

Example 4 In a 500 ml cylindrical separable flask, 77 g (0.3 mol) of monoethanolamine salt of 3-sulfopropyl acrylate and 108 g (0.2 mol of methoxypolyethylene glycol monomethacrylate (containing 10 ethylene oxide units per molecule on average)). ), 0.0385 g (0.00025 mol) of N, N-methylenebisacrylamide and 270 g of water were charged and stirred to dissolve uniformly. After purging the inside of the flask with nitrogen, the mixture was heated to 40 ° C. in a hot water bath, 0.5 g of a 10% ammonium persulfate aqueous solution and 0.5 g of a 1% L-ascorbic acid aqueous solution were added, and stirring was stopped to carry out polymerization. After the initiation of polymerization, heat was generated, and after 30 minutes, the temperature rose to 68 ° C. After confirming that the temperature of the polymerization system started to drop, raise the temperature of the water bath to 90 ° C and
Hold at 1 ° C for 1 hour. The hydrogel of the obtained crosslinked polymer was subdivided, then dried, pulverized, and classified to obtain a 200-mesh standard sieve-passed product.

Next, 20 g of this 200-mesh standard sieve passed material is subjected to relative humidity of 80%.
It was left in the room for 1 hour to absorb 2 g of water uniformly. This was dispersed in 80 g of toluene, 4 g of ethyl silicate 40 (manufactured by Colcoat Co., Ltd.) was added to the obtained dispersion, and the mixture was kept at 70 ° C. for 4 hours. Then, the solid content of this dispersion was dried over to obtain a salt-resistant water-absorbing agent (4) of the present invention.

Comparative Example 4 A hydrogel of a crosslinked polymer obtained in the same manner as in Example 4 was dried and pulverized, and then classified with a 200 mesh standard sieve,
A comparative water absorbing agent (4) was obtained.

Examples 5-8 and Comparative Examples 5-8 Salt-resistant water-absorbing agent (1) of the present invention obtained in Examples 1-4
(4) and the comparative water absorbing agent (1) obtained in Comparative Examples 1 to 4.
Each of (4) to (4) was allowed to stand in a constant temperature and humidity chamber at 25 ° C. and 60% RH, and the fluidity after 0 to 2 hours was visually examined. The results are shown in Table 1 together with the water absorption capacity.

Examples 9 to 12 and Comparative Examples 9 to 12 Salt-resistant water absorbents (1) to (4) obtained in Examples 1 to 4 and comparative water absorbents (1) to (4) obtained in Comparative Examples 1 to 4 )
60 g each, chloroprene rubber 100 g, zinc flower (1
No.) 5g, magnesium oxide 4g, P, P'-diaminodiphenylmethane 2g and 2-mercaptobenzothiazole 2g
Was kneaded with a roll for 15 minutes and then press-vulcanized at 160 ° C. for 20 minutes to obtain a rubber composite sheet having a thickness of 1 mm. This sheet was cut into 2 cm × 2 cm, and the swelling ratio when immersed in synthetic seawater was measured over time to examine the swelling rate and stability over time of the sheet. The results are shown in Table 2.

Claims (3)

[Claims] 1. A general formula (I) (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
A linear or branched alkylene group, X is -NH-
Alternatively, -O- and Y represent hydrogen, an alkali metal, an alkaline earth metal, an ammonium group or an organic substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer 20
On the surface of the crosslinked polymer particles obtained by polymerizing a monomer component consisting of 100 mol% and other polymerizable monomer 0 to 80 mol% in the presence of a crosslinking agent, a compound of the general formula (II) (R ³ _m SiX) _4-m (II) (wherein R ³ may have a substituent, an alkyl group, an aryl group or an unsaturated aliphatic residue, X is an alkoxy group,
Acyloxy group, hydrogen atom, halogen atom or hydroxyl group,
m represents an integer of 0 or 1 to ^3, and m R ³ and 4-
The m Xs may be different from each other. ) A salt-resistant water-absorbing agent to which a silicon compound represented by and / or a condensate of 2 to 10 mer thereof is attached. 2. General formula (I) (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
A linear or branched alkylene group, X is -NH-
Alternatively, -O- and Y represent hydrogen, an alkali metal, an alkaline earth metal, an ammonium group or an organic substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer 20
Water obtained by polymerizing a monomer component consisting of 100 mol% and other polymerizable monomer 0 to 80 mol% in the presence of a cross-linking agent and in the range of 1 to 200 wt% based on the absolute dry weight. The cross-linked polymer containing the compound of the formula (II) (R ³ _m SiX) _4-m (II) (wherein R ³ may have a substituent, an alkyl group, an aryl group or an unsaturated group) Aliphatic residue, X is an alkoxy group,
Acyloxy group, hydrogen atom, halogen atom or hydroxyl group,
m represents an integer of 0 or 1 to ^3, and m R ³ and 4-
The m Xs may be different from each other. ) Is dispersed in a substantially inert solvent in the silicon compound represented by the formula (1) and / or its 2- to 10-mer, and the polymer compound crosslinked dispersion contains the silicon compound represented by the general formula (II) and / or Alternatively, the 2 to 10 mer thereof is added at a ratio in the range of 0.1 to 100 parts by weight to 100 parts by weight of the crosslinked polymer, and then the silicon compound and / or the 2 to 10 mer thereof is added. By maintaining the molecular crosslinked body dispersion liquid at a temperature of 0 to 200 ° C., the silicon compound and / or 2 to 10 thereof can be obtained.
A method for producing a salt-resistant water-absorbing agent, which comprises subjecting a monomer to a condensation reaction. 3. The method for producing a salt-resistant water-absorbing agent according to claim 2, wherein the crosslinked polymer particles in the crosslinked polymer dispersion have an average particle diameter of 100 μm or less.