Seitetsu Kagaku Co., Ltd.

Yuji Sakamoto

Morio Nakamura

Shigeji Obayashi

Takushi Yamamoto

Hitoshi Tanaka

Yasuhiro Shimada

Toshikazu Nakanishi

A water-absorbent resin composition having superior gel stability which comprises a water-absorbent resin, at least one oxygen-containing reducing inorganic salt and, optionally, at least one organic antioxidant.

Water-absorbent resin composition

A water-absorbent resin having excellent physical properties can be produced by a process wherein an aqueous solution containing an .alpha.,.beta.-unsaturated carboxylic acid and an alkali metal salt thereof in a total amount of 25% by weight or more is subjected to polymerization with a radical polymerization initiator in a petroleum-based hydrocarbon solvent in the presence or absence of a crosslinking agent, characterized by using, as a surfactant, a polyglycerine--fatty acid ester having an HLB of 2 to 16 and represented by the general formula ##STR1## (wherein R is an acyl group or hydrogen atom and n is an integer of 0 to 8).

Process for producing a water-absorbent resin

A water-absorbent resin having an appropriate particle size and a narrow particle size distribution can be obtained by adding a powdered inorganic material in a proportion of 0.000005-0.2 part by weight to 1 part by weight of a water-absorbent resin containing therein a carboxylate as a component of the polymer with agitation in an inert solvent in the presence of 0.1-5.0 parts by weight of water and 0.005-0.2 part by weight of a surfactant and then removing water and the inert solvent by distillation.

Process for granulating a water-absorbent resin employing (a) water (b)

A water-absorbent resin usable as a suitable water absorbent in sanitary materials and other fields can be produced by subjecting an aqueous solution of an .alpha.,.beta.-unsaturated carboxylic acid and of an alkali metal salt thereof to polymerization with a radical polymerization initiator in a petroleum-based hydrocarbon solvent in the presence or absence of a crosslinking agent and, in this polymerization, using a saccharose-fatty acid ester as a protective colloid agent.

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Himeji, Japan

Yuji Sakamoto