Patent ID: 7829070

Claim:
An ampholytic copolymer comprising a molar excess of anionogenic and/or anionic groups, obtained by free radical polymerization of a) at least one branched C 3 -C 5 -alkyl acrylate, b) acrylic acid and methacrylic acid, with the proviso that the proportion by weight of acrylic acid is equal to or greater than the proportion by weight of methacrylic acid, and c) a monomer composition comprising c1) at least one compound having an α,β-ethylenically unsaturated double bond capable of free radical polymerization and at least one anionogenic and/or anionic group per molecule and c2) at least one compound having an α,β-ethylenically unsaturated double bond capable of free radical polymerization and at least one cationogenic and/or cationic group per molecule, the molar ratio of anionogenic and anionic groups of component c1) to cationogenic and cationic groups of component c2) being about 1:1.