Patent ID: 9388263
Filing Date: 2016-07-12
CPC Classification: C02F,C08F,C23F

Claim Text:
1. A (meth)acrylic acid-based copolymer comprising, as essential structural units: a structural unit (a) derived from a monomer represented by the following formula (1) in an amount of 2% by mole or more and 9% by mole or less relative to 100% by mole of structural units derived from all monomers; and a structural unit (b) derived from a (meth)acrylic acid or a salt thereof in an amount of 91% by mole or more and 98% by mole or less relative to 100% by mole of structural units derived from all monomers, wherein the copolymer contains a sulfonic acid group or a salt thereof at at least one end of the main chain and has a weight average molecular weight of 7000 to 100000, wherein R 2 represents a hydrogen atom or a methyl group; and X and Y each independently represent a hydroxyl group or a sulfonic acid group or a salt thereof, with at least one of X and Y representing a sulfonic acid group or a salt thereof.