| 摘要 |
PROBLEM TO BE SOLVED: To provide a water-soluble (meth)acrylic acid polymer which is satisfactory in both excellent calcium resistance and thickening capabilities, has a much reduced insolubles content, can be desirably used in many uses, and is industrially useful. SOLUTION: The water-soluble polymer is obtained by polymerizing a monomer component containing 60 to 95 mol % (meth)acrylic acid (salt) monomer (A), 5 to 40 mol % (meth)acrylic ester monomer (B) represented by formula (1): CH<SB>2</SB>=C(R)-COOZ<SP>1</SP>(O)<SB>p</SB>Z<SP>2</SP>OX, and 0 to 35 mol% other monomers (C) copolymerizable with monomers (A) and (B), (provided that the total amount of monomers (A), (B), and (C) is 100 mol %) and has a viscosity of at least 10 mPa s, an insolubles content of at most 5 mass %, and a calcium resistance of at least 5 ml when measured on a 0.2 mass % aqueous solution. In formula (I), R is a hydrogen atom or a methyl group; Z<SP>1</SP>and Z<SP>2</SP>, which may be the same or different from each other, are each an 8C or lower alkylene group; X is a 4C or lower hydrocarbon group; and p is an integer of 0 or 1. COPYRIGHT: (C)2006,JPO&NCIPI
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