Patent ID: 8790424

Claim:
A copolymer, comprising: (i) 10 to 90 mol % of repeating units of the structure W1 wherein R 1 and R 2 are each independently hydrogen, C 1 - to C 4 -alkyl or a carboxyl ester moiety of formula —COOR 9 , in which R 9 is a C 6 - to C 30 -hydrocarbyl radical and where one of the variables R 1 and R 2 is hydrogen or C 1 - to C 4 -alkyl and the other is a carboxyl ester moiety of the formula —COOR 9 , and R 3 and R 4 are each independently hydrogen, C 1 - to C 4 -alkyl, a carboxyl ester moiety of the formula —COOR 9 , in which R 9 is a C 6 - to C 30 -hydrocarbyl radical, or carboxyl groups which may also be present in form of alkali metal, alkaline earth metal or an ammonium salt thereof, in which one of the variables R 3 and R 4 is hydrogen or C 1 - to C 4 -alkyl and the other is a carboxyl ester moiety of the formula —COOR 9 , and/or a carboxyl group which may also be present in the form of the alkali metal, alkaline earth metal or ammonium salt thereof; and (ii) 90 to 10 mol % of repeating units of structure W2 wherein R 5 is a radical of a carboxylic ester of formula -A-CO—O—R 10 in which A is a C 1 - to C 20 -alkylene group and the variable R 10 is a C 1 - to C 30 -hydrocarbyl radical, and R 6 , R 7 and R 8 are each independently hydrogen or C 1 - to C 8 -alkyl, wherein a sum of the repeating units W1 and W2 adds up to 100 mol %.