Patent ID: 7405263

Claim:
A process for preparing (meth)acrylic acid copolymers, which comprises the following process steps: (1) free-radical polymerization of(meth)acrylic acid in the presence of isopropanol with or without water, with a polymer I resulting, and (2) amidating the polymer I originating from process step (1) by reaction with at least one aminoalkanesulfonic acid, wherein the (meth)acrylic acid copolymers comprise (a) from 50 to 75% by weight of a poly(meth)acrylic acid basic structure, (b) from 5 to 20% by weight of at least one unit which is bound to the basic structure and is selected from the group consisting of isobutene units, terelactone units and isopropanol units, and (c) from 5 to 40% by weight of amide units based on aminoalkyl-sulfonic acids, the total weight of the units in the (meth)acrylic acid copolymer being 100% by weight and all weights being based on the (meth)acrylic acid copolymer.