| 摘要 |
This acrylic acid-based copolymer contains a structural unit (x) that is derived from an acrylic acid or a sodium salt thereof and a structural unit (y) that is derived from 2-acrylamide-2-methylpropane sulfonic acid or a sodium salt thereof. The content ratios of the structural unit (x) and the structural unit (y) are respectively 35-90% by mass and 10-65% by mass if the total of the structural units is taken as 100% by mass. This acrylic acid-based copolymer has a weight average molecular weight of 2,000-30,000, and the content ratio of acrylic acid-based copolymers having a molecular weight of 70,000 or more is 0.30% by mass or less relative to the total mass of all the polymers. |
