| 主权项 |
1. A method for making a copolymer,
wherein the copolymer comprises as monomers, in polymerized form, 45 to 55% by weight of an unsaturated amide of the following structure wherein R1 is selected from the group consisting of H and C1-C8 alkyl, R2 is selected from the group consisting of H and C1-C8 alkyl, R3 is selected from the group consisting of H and C1-C8 alkyl, 35-45% by weight of an acrylic acid ester of the following structure wherein R4 is selected from the group consisting of C1-C12 alkyl, R5 is selected from the group consisting of H and C1-C12 alkyl, 9 to 15% by weight of an acidic monomer comprising a C═C double bond and a COOH group and 0 to 10% by weight of at least one further monomer having at least one C═C double bond, wherein the acidic monomer is optionally partially or completely neutralized with a neutralizing agent, said method comprising polymerizing the monomers in a solution comprising the monomers and a solvent, wherein the solvent comprises water and an alcohol selected from the group consisting of ethanol, isopropanol, n-butanol, tert-butanol, pentanol, pentanedioh and mixtures thereof. |
