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AssigneeSumitomo Chemical Company, Limited
InventorsShuji Kitamura, Fumio Fujita, Toshihiro Oonishi, Yoshiharu Tatsukami, Masato Ogura, Masahiro Niwano, Masaru Oota, Toshifumi Tamura
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The invention is to provide the methods for producing highly water-absorbable and water-retainable hydrogels having a large particle diameter together with a sufficient gel strength. The method is characterized by use of a specific dispersing agent in the water-in-oil type inverse phase suspension polymerization of an .alpha.,.beta.-unsaturated carboxylic acid and/or its alkali metal salt. Due to the high water-absorbability and water-retainability, along with the superior gel strength and the stable gel structure, the hydrogels of the invention enlarge the conventional range of usages.
A method for producing hydrogels which comprises that, in producing the hydrogel by water-in-oil type inverse phase suspension polymerization of an .alpha.,.beta.-unsaturated carboxylic acid monomer and/or its alkali metal salt in the presence or absence of a cross-linking agent, a carboxyl-containing polymer having affinity to the organic solvent is used as the dispersing agent.
Dependencies are inferred from the claim text.