Patent ID: 8022150

Claim:
A process for preparing polyoxyalkylene-polysiloxane block polymers of the general formula (I) C—B—(AB) a —C 1 (I) in which A is a polyoxyalkylene block of the general formula —(C n H 2n O) b —, B is a polysiloxane block of the general formula —(SiR 2 —O) c —, C and C 1 are identical or different alkoxypolyoxyalkylene radicals of the general formula Z—O—(CH 2 —CH(R 1 )O) d —, R are identical or different C 1-4 alkyl radicals or phenyl radicals, with the proviso that at least 90% of the radicals R are methyl radicals, R 1 are identical or different hydrogen, C 1-12 alkyl radicals or phenyl radicals, Z is an alkyl, alkylene, aryl or alkylaryl radical, a is 1 to 20, b is an average value from 10 to 130, c is 3 to 100, d is independently at each occurrence in C/C 1 values from 2 to 20, with the proviso that the average value is situated in the range 2 to <15, n is 2 to 12, with an average numerical value of 2.7 to 4.0, by reacting A) polyoxyalkylene alcohols of the general formula R 2 —(O—(C n H 2n O) b —H) e , in which R 2 is an e-valent hydrocarbon radical and e is 2 to 6, with B) polysiloxanes of the general formula Cl—(R) 2 —Si—(SiR 2 —O) c —Si(R) 2 —Cl, which comprises also using C) polyoxyalkylene alcohols of the general formula Z—O—(CH 2 —CH(R 1 )O) d —H to regulate the molar weight.