| abstract |
A process for the preparation of a copolymer comprises reacting in an aqueous medium at a temperature of from 25° C. to 100° C. in the presence of from 1.0-25 weight percent based on the total weight of a), b) and c) of a free-radical initiator,a) at least one monomer selected from the group consisting of alpha,beta-unsaturated monocarboxylic acids and their salts, alpha,beta-unsaturated dicarboxylic acids, their half-esters free of polyoxyalkylene side chains and their salts,b) at least on olefinic monomer selected from the group consisting of aromatic vinyl compounds, vinyl ethers, vinyl esters, nitrogen-containing vinyl compounds and aliphatic olefins, andc) from 0.01 to 30 weight percent based on the total amount of a), b) and c) of at least one hydrophobic compound free of olefinic unsaturation containing units of the formula:wherein R1 is independently at each occurrence selected from the group consisting of hydrogen and C1-C4 alkyl, with the proviso that at least one R1 is selected from the group consisting of C1-C4 alkyl. |