Patent ID: 7759402

Claim:
A method of defoaming an aqueous solution or dispersion which comprises of adding an effective amount of a grafted copolymer P based on polyoxyalkylene-polysiloxane block copolymers of the general formula (I) in which the radical A is a polyoxyalkylene block of the average formula (II) [(C 2 H 4-d R′ d O) n (C x H 2x O) r (C 2 H 4-d R″ d O) t ] (II) in which d is from 1 to 3, n is ≦0, x is from 2 to 10, r is ≦0, t is ≦0, n+r+t is ≦1, and R′ is a monovalent aromatic, optionally substituted hydrocarbon radical, R″ is a hydrogen radical or a monovalent hydrocarbon radical having 1 to 18 C atoms, R 1 is an H atom, a monovalent organic linear or branched alkyl radical having the chain length C 1 -C 40 or a carboxyl radical of an optionally branched alkyl or aryl ester, B is a polysiloxane block of the average formula (III) in which R 2 are identical or different and comprise an alkyl radical having 1 to 4 carbon atoms or a phenyl radical and y has a value from 5 to 200, m has a value from 2 to 100, p has a value from 0 to 1 and q has a value from 0 to 1, or of the formula (IV) in which the radicals R 1 , A, B and m, p and q have the abovementioned meaning and C is a linear or branched alkylene radical having 2 to 20 carbon atoms, to an aqueous solution or dispersion.