Patent ID: 8222303

Claim:
Defoamer formulations comprising (A) siloxane-based antifoams and (B) silicone polyethers prepared by in a first step, reacting organopolysiloxanes (1) containing from 0.05% to 1.6% by weight of Si-bonded hydrogen atoms with unsaturated polyethers (3) of the formulae: CH 2 ═CR 1 —(CH 2 ) a O(C 2 H 4 O) b R 1 (Ia) CH 2 ═CR 1 —(CH 2 ) a O(C 2 H 4 O) b (C 3 H 6 O) c R 1 (Ib) CH 2 ═CR 1 —(CH 2 ) a O(C 3 H 6 O) c R 1 (Ic), where R 1 is a hydrogen atom or a hydrocarbon radical having 1 to 6 carbon atoms, a is 0 or an integer from 1 to 16, b is an integer from 1 to 50, and c is an integer from 1 to 50, with the proviso that the sum of b+c is at least 10 and that a mixture of at least two different kinds of polyethers from the group of the formulae (Ia), (Ib) and (Ic) is used, and with the further proviso that the reaction takes place with a ratio of about 0.2 to 0.7 gram atoms of Si-bonded hydrogen per mol of aliphatic double bonds in the unsaturated polyethers, and in a second step, further reacting the reaction product from (1) and (3) with organopolysiloxanes (2) containing from 0.01% to 0.5% by weight of Si-bonded hydrogen atoms, with the proviso that the reactions in the first and second steps are carried out in the presence of catalysts (4) which promote the addition of Si-bonded hydrogen to aliphatic double bonds, and that the ratio of the weight concentration of Si-bonded hydrogen in organopolysiloxane (1) to the weight concentration of Si-bonded hydrogen in organopolysiloxane (2) is at least 2.0.