| abstract |
The present invention describes a polymer useful as viscosity index improver comprising units derived from one or more ethylenically unsaturated ester compounds of formula (I), where R is hydrogen or methyl, R 1 means a linear, branched or cyclic alkyl residue with 1-6 carbon atoms, R 2 and R 3 independently represent hydrogen or a group of the formula -COOR', where R' means hydrogen or a alkyl group with 1-6 carbon atoms, units of one or more ethylenically unsaturated ester compounds of formula (II), where R is hydrogen or methyl, R 4 means a 2-alkyl branched alkyl residue with 12-18 carbon atoms, R 5 and R 6 independently are hydrogen or a group of the formula - COOR' ', where R' ' means hydrogen or an alkyl group with 12- 18 carbon atoms, and units of one or more ethylenically unsaturated ester compounds of formula (III), where R is hydrogen or methyl, R 7 means a linear alkyl residue with 12-24 carbon atoms, R 8 and R 9 independently are hydrogen or a group of the formula -COOR' ', where R' ' means hydrogen or an alkyl group with 12-24 carbon atoms wherein said polymer comprises at least 10 % by weight units derived from one or more ethylenically unsaturated ester compounds of formula (I), based on the total weight of the polymer, said polymer comprises at least 10 % by weight units derived from one or more ethylenically unsaturated ester compounds of formula (II), based on the total weight of the polymer, and said polymer comprises at least 10 % by weight units derived from one or more ethylenically unsaturated ester compounds of formula (III), based on the total weight of the polymer. |