| abstract |
Branched organopolysiloxane (A) useful in defoamers, are prepared by irradiating with high energy radiation, organopolysiloxane (X) of the formula (1), in which R1 and R2 are independently monovalent unsubstituted or halogenated saturated C1-30 or unsaturated hydrocarbon radicals, or hydrogen, R3 is hydrogen or a monovalent C1-9 hydrocarbon radical, a is 0 or 1, n is an integer such that the viscosity of the organopolysiloxane (X) is 350-20,000 mPa sec at 25 °C and 1013 hPa, with the proviso that in the formula (1) at most 0.22 mol % of a is 1 and R2 is H, such that the viscosity of the organopolysiloxane (A) after irradiation is at least 40% higher than the viscosity of the organopolysiloxane (X). |