Use of water-insoluble polyoxyalkylene-polysiloxane mixed block copolymers for defoaming aqueous media

摘要

Water-insoluble polyoxyalkylene-polysiloxane block copolymers with polyoxyalkylene side chains containing blocks derived fro ethylene oxide, propylene oxide and n- or iso-butylene oxide are used as foam suppressants for aqueous media. The use of water-insoluble polyoxyalkylene-polysiloxane block copolymers of formula (I) as foam suppressants for aqueous me is claimed, in which R<1> and/or R<7> = R<2> or -(R<4>)w-(R<5>)x-(R<6>)-R<8>; R<2>, R<3> = 1-24C alkyl or optionally substituted phenyl with up to 24 C; R<4> = -O-, -NH-, -NR<2>-, -S- or -(O-Si(CH3)2)u-; u = 2-200; R<5> = 1-24C alkylene or -CnH2n-f-(R<2>)f-O-CmH2m-g-(R<2>)g-; f, g = 0-12; n, m = 1-18; R<6> = -O-(C2H4O)a-(CH2CH(CH3)O)b-(CH2CR<9>R<10>O)c-, with any sequence of polyoxyalkylene segments, especially block copolymers such as statistical polymers and combinations of thes R<9> = R<10> = methyl, or R<9> = H and R<10> = ethyl, with the proviso that the total content of C2H4O groups in all residues R<6> is not more than 40 wt%; a = 2-30; b = 2-50; c = 2-40; (a+b+c) = 6-100; R<8> = H, optionally substituted 1-6C alkyl or acyl; v = 3-200; w, x = 0 or 1; y = 0-200, with R<1> and/or R<7> = -(R<4>)w-(R<5>)x-(R<6>)-R<8> if y = 0