JPH02199104A - Water-absorptive resin and its production - Google Patents

Abstract

PURPOSE:To obtain the title resin which can retain its high water absorption ratio, a high gel strength and a high water absorption rate and is prevented from undergoing deformation or fracture upon exertion of pressure or shock by polymerizing a composition comprising a hydrolyzable and/or considerable inorganic compound and an ethylenically unsaturated water-soluble monomer to form a crosslinked polymer. CONSTITUTION:5-500 pts.wt. inorganic compound (A) having a hydrolyzable and/or considerable functional group, for example, an Si compound of RmSiX4-m (wherein R is an alkyl, an aryl or an unsaturated aliphatic residue; X is an alkoxy, an acyloxy, H, a halogen atom or OH; and m is 0 or 1-3) or an Al compound of the formula; R'nAlY3-n (wherein R' is an alkyl; Y is an alkoxy, H or a halogen atom; and n is 0 or 1-2) is mixed with 100 pts.wt. ethylenically unsaturated water-soluble monomer (e.g. acrylic acid or N,N-methylenebis- acrylamide), and the mixture is crosslinked by polymerization to form a water- absorptive resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel water-absorbing resin and a method for producing the same. More specifically, the present invention relates to a water absorbent resin that has a high water absorption rate and high gel strength even under pressure and is not easily deformed or destroyed even when pressure or impact is applied, and a method for producing the same.

(Conventional Technique #I) In recent years, water-absorbing resins that absorb tens to hundreds of times their own weight in water have been developed, and are used as water-absorbing agents for sanitary products, disposable diapers, etc., as water-retaining agents for agriculture and horticulture, and as sludge removal agents. It is being developed for use as an assimilation agent, anti-condensation agent for building materials, water stopper for civil engineering, desiccant, etc.

Examples of such water-absorbing resins include hydrolyzed products of starch-acrylonitrile graft polymers, neutralized products of starch-acrylic acid graft polymers, saponified products of vinyl acetate-acrylic acid ester copolymers, and acrylonitrile-based copolymers. There are hydrolysates of polymers or acrylamide copolymers or crosslinked products thereof, self-crosslinking sodium polyacrylate obtained by reverse phase suspension polymerization, and crosslinked products of partially neutralized polyacrylic acid. Starch-acrylic acid-vinyl sulfone ll-N as having
-Crosslinked product of methylpyridium chloride graft copolymer, sulfomethylated product of starch-sodium acrylate-acrylamide graft copolymer crosslinked product with formalin and sodium bisulfite, 2-acrylamide-2-methylpropanesulfonic acid-sodium acrylate Self-crosslinked products are known.

(2! Problems to be Solved by the Invention) However, although these water-absorbing resins have an excellent ability to absorb a large amount of water or aqueous liquid, they do not have sufficient gel strength after absorbing water, so they do not have sufficient pressure or amperage. It has the disadvantage that it easily deforms or breaks when pressure is applied, and that the water absorption capacity and water absorption rate decrease under pressure.

Therefore, as a method for improving the gel strength, methods such as increasing the crosslinking density have been proposed. However, although an improvement in gel strength is observed in this method, there are disadvantages such as a decrease in water absorption capacity, and it is not possible to improve gel strength while maintaining a high water absorption capacity.

In addition, methods to improve the water absorption rate include a method of making the surface of a water-absorbing resin powder hydrophobic with alcohol or the like, a method of crosslinking the surface with an epoxy compound, or a method of coating the surface with an amorphous compound. However, these methods only improve the diffusion of water in the gaps between the water-absorbing resin powders, and it is difficult to say that they can provide a sufficient water absorption rate. Further, there was also the problem that the water absorbing ability of the water absorbent resin was reduced by these treatments.

The present inventors have completed the present invention as a result of extensive research in order to solve the above problems.

Therefore, an object of the present invention is to provide a water-absorbing resin that has high gel strength and high water absorption rate while maintaining high water absorption capacity, and does not deform or break even when subjected to pressure or impact. be.

(Means and effects for solving the problems) The present invention comprises an inorganic compound (A) having a hydrolyzable and/or condensable functional group and a water-soluble monomer (8) having an unsaturated double bond. The present invention relates to a water-absorbing resin made of a polymer obtained by polymerizing and crosslinking a composition.

The present invention also provides polymerization and crosslinking of a water-soluble monomer (B) having an unsaturated double bond in the presence of an inorganic compound (A) having a functional group capable of hydrolysis and/or condensation/combination. The present invention relates to a method for producing a water-absorbing resin characterized by the following.

The inorganic compound (A) used in the present invention is not particularly limited as long as it has a hydrolyzable functional group or a condensable functional group in its molecule, such as orthomethylsilicate, orthoethylsilicate, etc. , orthoalkyl silicates such as orthopropyl silicate, orthobutyl silicate, and dimers thereof: pinyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, methylvinyldimethoxysilane, γ-(meth)acrylate 0 Xypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-
7minoethyl)aminopropyltrimethoxysilane, γ
-anilinopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane,
Silane coupling agents such as γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; methyltrimethoxysilane, methyltriethoxysilane, octadecyltrimethoxy Alkyl or arylalkoxysilanes such as silane, offdabcyltriethoxysilane, methyloctadecyldimethoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyljethoxysilane;
Phenyltrichlorosilane, diphenyldichlorosilane, triphenylchlorosilane, methyltrichlorosilane, methyldichlorosilane, dimethylchlorosilane, ethyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane, octadecyltrichlorosilane,
Silane compounds with halogen atoms such as methyloctadecyldichlorosilane and dimethyloctadecylchlorosilane; aluminum jetoxide, aluminum triethoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-5ec
- Aluminum compounds such as butoxide, aluminum tritert-butoxide, ethylaluminum dichloride, diethylaluminum ethoxide; water glass,
One or more selected from the group consisting of siloxane and the like can be used.

Among such inorganic compounds (A), inorganic compounds (A
) in the presence of the general formula (I>(R) S i (X) 4-
1 (I)■ (However, R is an alkyl group, an aryl group, or an unsaturated aliphatic residue that may have a substituent, X is an alkoxy group,
Acyloxy group, hydrogen atom, halogen atom or water! ! The group, - represents O or an integer of 1 to 3, one R and 4
- Each X may be different. ) or general formula (II) (R') AI(Y)3. (If)n (However, R' is an alkyl group that may have a substituent, Y
is an alkoxy group, hydrogen atom or halogen atom, n is 0
Alternatively, it represents an integer of 1 to 2, and n R's and 3-n Ys may be different from each other. ) is preferable.

The water-soluble monomer (8) used in the present invention includes the following! There is no particular restriction as long as the polymer a exhibits water absorbing properties such as swelling in water and forming a hydrogel, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and citraconic acid. Carboxyl group-containing monomers such as 2-(meth)acryloylethanesulfonic acid, 2-(meth)acryloylethanesulfonic acid,
2-(meth)acrylamide-7-ionic monobases such as sulfonic acid group-containing monomers such as 2-methylpropanesulfonic acid, vinylsulfonic acid, and styrenesulfonic acid, and salts thereof = (meth)acrylamide, N-substituted ( meth)acrylamide, 2-hydroxyethyl (meth)acrylate,
Nonionic suspensions such as 2-hydroxypropyl (meth)acrylate; diethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate,
Cationic monomers such as dimethylaminopropyl (meth)acrylamide and their quaternized products; vinylimidazole,
Examples include vinylpyridine and vinylpyrrolidone, and one or more of these can be used.

Among such water-soluble monomers (B), carboxyl group-containing QlI monomers and their salts, and sulfonic acid group-containing monomers are used because they can be polymerized and crosslinked to obtain water-absorbing resins with better water-absorbing ability. and its salts, and (meth)acrylamide, and preferably one or more selected from the group consisting of acrylic acid, methacrylic acid, 2-(meth)acryloylethanesulfonic acid, and 2-(meth)acrylamide. One or more selected from the group consisting of -2-methylpropanesulfonic acid, salts thereof, and (meth)acrylamide are preferred.

In addition, within the range that does not impede the performance of the obtained water absorbent resin,
A part of the water-soluble monomer (B) can be used in place of the hydrophobic monomer. Examples of such hydrophobic monomers include styrene, methyl (meth)acrylate, vinyl chloride, butadiene, isoprene, ethylene, and propylene, and one or more of these can be used.

The layer of the inorganic compound (A) used in the present invention may be suitably W4ilI depending on the gel strength and water absorption capacity required of the water-absorbing resin obtained, but the water-soluble monomer (B) 100
The range of 5 to 500 parts of acetic acid based on the weight of the parts is preferred. If the amount of the inorganic compound (A) is less than 5 parts by weight, the resulting water absorbent resin may have insufficient gel strength. Furthermore, if the amount of the inorganic compound (A) exceeds 500 parts by weight, the water absorbing ability of the resulting water absorbent resin may become insufficient.

In the present invention, in order to obtain a water-absorbing resin by polymerizing and crosslinking the water-soluble monolayer (B) in the presence of the inorganic compound (A), conventionally known polymerization and crosslinking methods of water-soluble monomers are used. should be adopted. Such polymerization/crosslinking methods include, for example, methods using radical polymerization catalysts, electron beams, ultraviolet rays,
Examples include methods of irradiating radiation such as rays and gamma rays.

Examples of radical polymerization catalysts include hydrogen peroxide, peroxides such as benzoyl peroxide and cumene hydroperoxide, azo compounds such as azobisisobutyronitrile, and radicals such as persulfates such as ammonium persulfate and potassium persulfate. A redox initiator is used, which is a generator or a combination of these and a reducing agent such as sodium bisulfite, L-ascorbic acid, or ferrous salt.

Various forms of polymerization can be adopted, including cast polymerization in which an aqueous monomer solution is injected into a polymerization vessel, and reverse phase suspension W4 polymerization in which an aqueous monomer solution is dispersed in an immiscible organic solvent. Preferred is a method (Japanese Patent Laid-Open No. 57-34101) in which the hydrogel polymer is polymerized while being fragmented by shearing force of a double-arm kneader. In addition, there is no particular restriction on the concentration of the water-soluble monomer (8) in the polymerization system, but considering ease of control of the polymerization reaction, yield, and economic efficiency, it is within the range of 20 to 80% by weight. It is preferable that there be.

As the solvent used to adjust the monomer solution concentration in the polymerization system, for example, water, methanol, ethanol, acetone, dimethylformamide, dimethyl sulfoxide, etc., and mixtures thereof can be used.

The temperature during polymerization varies depending on the type of catalyst used, but a relatively low temperature is preferable because the resulting polymer has a larger molecular spear. However, in order for the polymerization to be completed, it is necessary to
The temperature is preferably in the range of 0°C or lower.

In the present invention, in the presence of the inorganic compound (A), water-soluble mono9
When polymerizing and crosslinking polymer (8) to obtain a water-absorbing resin, self-crosslinking can be carried out without using a crosslinking agent, but since the crosslinking density of the resulting polymer can be freely controlled, It is preferable to add a crosslinking agent to the.

Examples of such crosslinking agents include vinylbenzene, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and polyprolene glycol di(meth)acrylate.
meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)
Compounds having two or more ethylenically unsaturated groups in one molecule such as acrylate, pentaerythritol di(meth)acrylate, N,N-methylenebisacrylamide, triallyl isocyanurate, trimethylolpropane diallyl ether; ethylene glycol, diethylene glycol, Polymers such as triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, jetanolamine, triethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbitol, sorbitan, glucose, mannitol, mannitan, sucrose, glucose, etc. Alcohols: 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-hexanethiol diglycidyl ether, tri Methylolpropane diglycidyl ether,
Examples include polyepoxy compounds such as trimethylolpropane triglycidyl ether and glycerin triglycidyl ether, and one or more of these can be used. In addition, when using a polyhydric alcohol as a crosslinking agent, it is preferable to heat-process at 150-250 degreeC, and when using a polyepoxy compound, it is preferable to heat-process at 50-250 degreeC after polymerization.

The amount of the crosslinking agent used is preferably the water-soluble monomer (B
), the molar ratio is within the range of 0.3 or less.

If the amount exceeds 0.3, the crosslinking density of the resulting polymer tends to become too large, resulting in a decrease in water absorption capacity.

When using the inorganic compound (A) in the present invention, it is necessary to add the inorganic compound (A) to the water-soluble monomer (B) before or during the polymerization of the water-soluble monomer (B). - Even if the inorganic compound (A) is added to the water-absorbing resin obtained by crosslinking, no improvement in gel strength is achieved. In particular, it is preferable to subject a composition obtained by adding the inorganic compound (A) to the water-soluble monomer (B) and uniformly mixing the mixture to the polymerization/crosslinking operation.

Further, in the present invention, a fragrance or a deodorizing agent may be added to the water-absorbing resin to impart aroma and deodorizing ability, or carbon black or activated carbon may be mixed before or after polymerization to improve light resistance.

(Effects of the Invention) The water-absorbing resin obtained by the present invention has high gel strength and high water absorption rate, so it has excellent resistance to compressive forces from rubber and other surrounding materials, water pressure on the seabed, etc. It exhibits water absorption ability and can retain the absorbed aqueous liquid for a long time even under pressure.

Therefore, the water-absorbing resin obtained in the present invention can be effectively used, for example, as a water-stopping agent or a water-retaining agent, and in particular, those kneaded with rubber and/or thermoplastic resin have a high swelling rate with aqueous liquids. Since the swelling ratio does not change over time due to pressure, it can be used as a water stop material for civil engineering, a water stop material for cables, a sealing material,
Effective as caulking material, backing material, film coating agent, sandwich sheet, etc.

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

Example 1 Acrylic acid 8 was placed in a 2000 d cylindrical separable flask.
2.801 Sodium acrylate 3240°N, N-methylenebisacrylamide 0.178Q.

Tetramethoxysilane (TMS) 20Q and water 684
g and stirred to uniformly dissolve.

After purging the inside of the flask with nitrogen, it was heated to 30°C in a hot water bath.
12% by weight aqueous sodium persulfate solution 4.60 and 1.
Adding 4.6Q of 2% by weight L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started.

After the vehicle was started, heat was generated and the temperature rose to 70°C after 20 minutes, but the temperature of the polymerization system was kept at 70°C and heated for 20 minutes to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was divided into small pieces, vacuum dried at air temperature, and crushed to obtain a water-absorbing resin with a water content of 2% by weight (1
) was obtained.

Example 2 In a 2000 d cylindrical separable flask, sodium salt of 2-sulfoethyl methacrylate 417Q, methacrylic 14'll, sodium methacrylate 16Q, N, N
- Prepare 0.1 g of methylenebisacrylamide, 97Q of tetramethoxysilane (TMS) and 644Q of water,
Stir to dissolve uniformly.

After purging the inside of the flask with nitrogen, it was heated to 40°C in a hot water bath.
10% by weight aqueous sodium persulfate solution 5.17G and 1
Adding 2.590 wt% L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started. Heat is generated after polymerization starts,
The temperature rose to 70°C after 55 minutes. After confirming that the temperature of the polymerization system had begun to drop, the water bath was raised to 90°C and heated for an additional hour to complete the polymerization.

The obtained hydrogel of the crosslinked polymer is divided into small pieces, dried under vacuum at room temperature, and crushed to obtain a water-absorbing resin with a water content of 2% by market weight (2
) was obtained.

9.64G and 1% by weight L-ascorbic acid aqueous solution 4
．． 820 was added, stirring was stopped, and polymerization was started.

After the start of polymerization, heat was generated, and the temperature rose to 80°C after 30 minutes.

After confirming that the temperature of the polymerization system has started to drop, turn off the water bath to
The temperature was increased to 0° C. and heated for an additional hour to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was divided into small pieces, vacuum dried at room temperature, and pulverized to obtain a water absorbent resin (3) with a water content of 2 fiffi%.

Example 3 In a 2000a+f cylindrical separable flask, 417G of sodium salt of 2-sulfoethyl methacrylate, 44Q1 methacrylic acid, 16G of sodium methacrylate, 159g of acrylamide, N.

N-methylenebisacrylamide 0.186Q, tetramethoxysilane (TMS) 129Q and water 965
Q was charged and stirred to uniformly dissolve it.

After purging the inside of the flask with nitrogen, it was heated to 40°C in a hot water bath.
10% by weight sodium persulfate aqueous solution Example 4 Acrylic 11 in a 2000 d cylindrical separable flask
182.801 Sodium acrylate 324Q.

N,N-methylenebisacrylamide 0.178g, aluminum triethoxide (ATE) 20a and water 6
84 g was charged and stirred to uniformly dissolve it.

After purging the inside of the flask with nitrogen, it was heated to 30°C in a hot water bath.
122 double round sodium persulfate aqueous solution 4.60 and 1.
Add 4.6 g of 2% by weight L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started.

After the start of polymerization, heat was generated and the temperature rose to 70° C. after 20 minutes. After that, the temperature of the polymerization system was maintained at 70° C. and heated for 20 minutes to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was finely divided, dried under vacuum at room temperature, and crushed to obtain a water-absorbent resin (4%) with a water content of 2%.
) was obtained.

Example 5 Acrylic in a 2000d cylindrical separable flask! 8
2.8Q, sodium acrylate 324Q.

N,N-methylenebisacrylamide 0.178Q.

271 g of aluminum triethoxide (ATE) and 684 g of water were charged and stirred to uniformly dissolve them.

After purging the inside of the flask with nitrogen, it was heated to 30°C in a hot water bath.
12% by weight aqueous sodium persulfate solution 4.69 and 1.
Adding 4.60% of 2% by weight L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started.

After the start of polymerization, heat was generated and the temperature rose to 70° C. after 20 minutes. After that, the temperature of the polymerization system was maintained at 70° C. and heated for 20 minutes to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was divided into small pieces, vacuum dried at room temperature, and crushed to obtain a water-absorbing resin with a water content of 2% by weight.
5) was obtained.

Example 6 Acrylic R2 in a 2000d cylindrical separable flask
0,7o, sodium acrylate 810, N,N-methylenebisacrylamide 0.05Q 1 aluminum triethoxide (ATE) 4000 and water 171Q
was added and stirred to uniformly dissolve.

After purging the inside of the flask with nitrogen, it was heated to 30°C in a hot water bath.
12% by weight aqueous sodium persulfate solution 1.10 and 1.
Add 1.10% of 2% by weight L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started.

After the start of polymerization, heat was generated and the temperature rose to 70° C. after 20 minutes. After that, the temperature of the polymerization system was maintained at 70° C. and heated for 20 minutes to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was divided into small pieces, vacuum dried at room temperature, and crushed to obtain a water absorbent resin (6% by weight) with a water content of 2% by weight.
) was obtained.

Example 7 Cyclohexane 10000 and sorbitan monostearate (Rheodol 5P-810 manufactured by Kao ■) IO were placed in a 2000 m cylindrical separable flask equipped with a dropping funnel.
After charging Q, the inside of the flask was purged with nitrogen while heating to 60° C. and stirring in a hot water bath.

Meanwhile, in the dropping funnel, sodium salt 120Q of 2-sulfoethyl methacrylate and acrylamide 5 (1,N,N
- After adding 0.7Q of methylenebisacrylamide and 4 (l) of ethyltrichlorosilane and mixing uniformly, while purging the inside of the dropping funnel with nitrogen, 2.2' -azobis(2
-amidinopropane) dihydrochloride (Wako Pure Chemical
fjV-50) 0.5a and water 50atr added,
The mixture was mixed uniformly at room temperature to prepare m aqueous monomer solutions.

Next, the monomer aqueous solution was poured into the flask from the dropping funnel, and the monomer aqueous solution was suspended in cyclohexane.
Polymerization was initiated at ℃.

After polymerization was carried out at 60°C for 3 hours, a reflux condenser was attached to the separable flask and the temperature of the water bath was raised to 90°C, and water in the system was distilled off by azeotropic distillation with cyclohexane. When water was no longer distilled off, the polymer was separated from the cyclohexane, and the polymer powder was dried under reduced pressure at 80°C to obtain a water absorbent resin (7) with a water content of 2% by weight.

Comparative Example 1 Acrylic acid 8 was placed in a 2000-cylindrical separable flask.
2.8Q, acrylic acid, 3240°N, N-
Methylenebisacrylamide 0.178a and water 68
4Q was charged and stirred to uniformly dissolve it.

After purging the inside of the flask with nitrogen, it was heated to 30°C in a hot water bath.
12% by weight per l1Ii! ! 4.60 Q of aqueous sodium solution and 4.6 Q of 1.2% by weight L-ascorbic acid aqueous solution were added, stirring was stopped, and polymerization was started.

After the start of polymerization, heat was generated and the temperature rose to 70°C after 20 minutes, but the temperature of the polymerization system was maintained at 70°C and heated for 20 minutes to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was divided into small pieces, vacuum dried at room temperature, and crushed to obtain a comparative water-absorbent tree J with a water content of 2% by weight.
ll(1) was obtained.

Comparative Example 2 In a 2000 d cylindrical separable flask, 417 g of sodium salt of 2-sulfoethyl methacrylate, 44Q methacrylic acid, 16 g of sodium methacrylate, N, N-
Methylenebisacrylamide 0.1Q and water 644Q
was added and stirred to uniformly dissolve.

After purging the inside of the flask with nitrogen, it was heated to 40°C in a hot water bath.
5.17 g of 10% by weight aqueous sodium persulfate solution and 1
wt% L~add ascorbic acid aqueous solution 2.590,
Stirring was stopped and polymerization was started. Heat is generated after polymerization starts,
The temperature rose to 70°C after 55 minutes. After confirming that the temperature of the polymerization system had begun to drop, the water bath was raised to 90°C and heated for an additional hour to complete the polymerization.

The obtained hydrogel of the crosslinked polymer was finely divided, dried under vacuum at room temperature, and pulverized to obtain a comparative water absorbent resin (2) having a water content of 2% by weight.

Comparative Example 3 417 g of sodium salt of 2-sulfonide methacrylate, methacrylic 144a, sodium methacrylate 16Q1, acrylamide 159Q, N were placed in a 2000 d cylindrical separable flask.

0.186 Q of N-methylenebisacrylamide and 965 Q of water were charged and stirred to uniformly dissolve.

After purging the inside of the flask with nitrogen, it was heated to 40°C in a hot water bath.
10% by weight sodium persulfate aqueous solution 9.64G and 1
Adding 4.820% by weight L-ascorbic acid aqueous solution,
Stirring was stopped and polymerization was started. Heat is generated after polymerization starts,
The temperature rose to 80°C after 30 minutes. After confirming that the temperature of the polymerization system had begun to drop, the water bath was raised to 90°C and heated for an additional hour to complete one polymerization.

Obtained rack I! After the hydrogel of the polymer was finely divided, it was vacuum dried at room temperature and pulverized to obtain a comparative water absorbent resin (3) with a water content of 2%.

Comparative Example 4 An aqueous monomer solution was prepared in the same manner as in Example 7 except that ethyltrichlorosilane 40Q in Example 7 was not used.

Using this monomer aqueous solution that does not contain ethyltrichlorosilane, polymerization was carried out in the same manner as in Example 7, followed by water distillation, polymer separation, and drying. (4) was obtained.

In a beaker with an internal volume of 200 m, 4q of water-absorbing resin is added to 100
The mixture was dispersed and uniformly swollen in the physiological saline solution of Q with sufficient stirring to prevent lumps from forming.

The gel obtained by leaving the lid on for 1 hour at room temperature was measured using a Neo Card meter (manufactured by Iio Denki N), which is used as a food quality control device, to measure the gel strength. I asked for

The results are shown in Table 1.

Table 1 Example 8 The water absorbent resins (1) to (7) obtained in Examples 1 to 7 and the comparative water absorbent resins (1) to (4) obtained in Comparative Examples 1 to 4 were treated by the following method. Gel strength was measured.

As is clear from Table 1, the water absorbent resin obtained by the present invention has high gel strength even after water absorption.

Example 9 The water absorbent resins (1) to (7) obtained in Examples 1 to 7 and the comparative water absorbent resins (1) to (4) obtained in Comparative Examples 1 to 4 were treated under pressure by the following method. The water absorption capacity was measured.

0.5g of water-absorbing resin is sandwiched between 1.0g of pulp,
An absorbent body (in the form of a disc sheet with a diameter of 90 shoes) for measuring water absorption capacity under pressure was prepared.

The water absorption capacity of this absorbent body under pressure was measured as follows using the apparatus shown in FIG.

First, artificial urine (urea 1.9% by weight, salt 0.8% by weight,
Calcium chloride 0.1% by weight and magnesium sulfate 0
．． The cock at the top 1 of the bilulet containing an aqueous solution containing 1% by weight was closed, and the measuring table 2 and the air port 3 of the closed bilulet were set at the same level.The air port 3 of the billet was then opened. Subsequently, the absorber 5 prepared as described above was placed on the glass filter 4 with a diameter of 90 - on the measuring table 2, and a load 6 (20
Q/n2) was loaded. Then 1 minute, 3 minutes, 5 minutes and 1
After 0 minutes, the amount (W) of artificial urine absorbed into the absorbent body was measured over time based on the biuret reading.

In addition, the water absorption capacity of the water-absorbing resin under pressure was calculated using the following formula, using the artificial urine absorption machine as a blank (WO) in which an absorber made of only 1.0 g of pulp with no water-absorbing resin sandwiched thereon was placed. The results are shown in Table 2.

Water absorption capacity under pressure (d/Q>= absorbed artificial urine m (W) - blank absorption ff1
(WO) Table of weight of water-absorbing resin contained in the absorbent body Measurement at the top of the bilette Air port glass filter absorption body weight Artificial urine

Claims (1)

[Claims] 1. Polymerization and crosslinking of a composition consisting of an inorganic compound (A) having a functional group that can be hydrolyzed and/or condensed and a water-soluble monomer (B) having an unsaturated double bond. A water-absorbing resin made from a polymer obtained by 2. The inorganic compound (A) having a functional group capable of hydrolysis and/or condensation has the general formula (I) (R)_mSi(X)_4_-_m(I) (However, R may have a substituent , an alkyl group, an aryl group or an unsaturated aliphatic residue, X is an alkoxy group, an acyloxy group, a hydrogen atom, a halogen atom or a hydroxyl group, m is 0 or 1
represents an integer of ~3, and m R's and 4-m X's may be different from each other. ) or general formula (II) (R')_nAl(Y)_3_-_n(II) (however,
R' is an alkyl group which may have a substituent, Y is an alkoxy group, a hydrogen atom or a halogen atom, n is 0 or an integer of 1 to 2, and n R's and 3-n Y's are each May be different. ) The water-absorbing resin according to claim 1, which is an aluminum-containing compound represented by: 3. The water-soluble monomer (B) having an unsaturated double bond was selected from the group consisting of a carboxyl group-containing monomer and its salt, a sulfonic acid group-containing monomer and its salt, and (meth)acrylamide. The water-absorbing resin according to claim 1, which is one or more kinds. 4. The water-absorbing resin according to claim 1, wherein the amount of the inorganic compound (A) used is in the range of 5 to 500 parts by weight based on 100 parts by weight of the water-soluble monomer (B). 5. Water absorption characterized by polymerizing and crosslinking a water-soluble monomer (B) having an unsaturated double bond in the presence of an inorganic compound (A) having a functional group that can be hydrolyzed and/or condensed. Method of manufacturing resin. 6. The inorganic compound (A) has the general formula (I) (R)_mSi(X)_4_-_m(I) (However, R is an alkyl group, an aryl group, or an unsaturated aliphatic residue which may have a substituent. group, X is an alkoxy group, acyloxy group, hydrogen atom, halogen atom or hydroxyl group, m is 0 or 1
represents an integer of ~3, and m R's and 4-m X's may be different from each other. ) or general formula (II) (R')_nAl(Y)_3_-_n(II) (however,
R' is an alkyl group which may have a substituent, Y is an alkoxy group, a hydrogen atom or a halogen atom, n is 0 or an integer of 1 to 2, and n R's and 3-n Y's are each They can be different. ) The method for producing a water-absorbing resin according to claim 5, which is an aluminum-containing compound represented by: 7. Water-soluble monomer (B) is one or more selected from the group consisting of carboxyl group-containing monomers and their salts, sulfonic acid group-containing monomers and their salts, and (meth)acrylamide. The method for producing a water absorbent resin according to claim 5. 8. The method for producing a water-absorbing resin according to claim 5, wherein the amount of the inorganic compound (A) used is in the range of 5 to 500 parts by weight relative to 100 parts by weight of the water-soluble monomer (B).