| 摘要 |
PROBLEM TO BE SOLVED: To provide a water-soluble polymer obtained by radically copolymerizing an unsaturated carboxylic acid monomer with a vinyl lactam monomer in an aqueous solvent using a water-soluble polymerization initiator, where metal impurities are reduced to a level of at most 100 ppb. SOLUTION: The manufacturing method of the water-soluble polymer comprises obtaining the water-soluble polymer compound by radically copolymerizing the unsaturated carboxylic acid monomer with the vinyl lactam monomer in the aqueous medium using the water-soluble polymerization initiator, where the weight-average molecular weight is controlled within the range of 10,000-100,000. Subsequently, the metal impurities are removed from the water-soluble polymer using at least one adsorbing material selected from an adsorbing material composed of a resin having a cationic ion-exchanging group on the surface and an adsorbing material composed of a fibrous matter having added thereto a cationic charge-adjusting agent. COPYRIGHT: (C)2005,JPO&NCIPI
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