| 摘要 |
PURPOSE:To obtain a highly water-absorptive polymer which contains an extremely small amount of an unpolymerized monomer and is high in safety, by irradiating a highly water-absorptive polymer having a carboxyl group or carboxylate group with ultraviolet light in the presence of a specific amount of water. CONSTITUTION:A highly water-absorptive polymer having a carboxyl group and/or a carboxylate group is irradiated with ultraviolet light under such a condition that its water content may be 0.01-40pts.wt. per pt.wt. highly water- absorptive polymer, to obtain a high water-absorptive polymer wherein the amount of an unpolymerized monomer is lower than that of the highly water- absorptive polymer. As the highly water-absorptive polymer to be used, acrylic (salt) polymers, methacrylic (salt) polymers, starch/acrylic (salt) graft copolymers, etc. can be mentioned. As a case wherein a highly water-absorptive polymer is of a salt type, an alkali metal salt type, alkaline earth metal salt type, ammonium salt, amine salt, etc. can be mentioned, among which an alkali metal salt type is particularly preferred.
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