Patent ID: 7645360

Claim:
A defoamer formulation comprising (A) siloxane-based antifoams and (B) polysiloxane copolymers prepared by reacting in a first step organopolysiloxanes (1) which have per molecule at least one Si-bonded hydrogen atom, with substantially linear oligomeric or polymeric compounds (2) of the formula R 1 -(A-C n H 2n ) m -A 1 -H (I), where R 1 is a monovalent hydrocarbon radical to which Si—H groups can be added in a hydrosilylation reaction, A is —O—, A 1 is —O—, n is an integer from 1 to 20, and m is a positive integer, to form an intermediate (4); and, in a second step, reacting the intermediate (4), containing H-A 1 groups, with organic compounds (5) which have per molecule at least two isocyanate groups, with the proviso that the water content of the compounds (1) and (2) used for preparing the polysiloxane copolymers is lower than 2000 ppm by weight, based on the total weight of compounds (1) and (2).