Copolymers in their salt form useful as component (b-12) therefore contain carboxyl groups in their salt form as well as other units as are obtained by copolymerization of acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, with monomers such as ethylene, butylene isobutylene, propylene, isoprene, butadiene and/or styrene or other known monomers of this class with subsequent