Patent ID: 6451863
Filing Date: 2002-09-17
Classification: B01D

Abstract:
A method for defoaming aqueous media which comprises adding to the aqueous media a defoamer comprising a water-insoluble polytoxy-1,4-butanediyl)-containing polyoxyalkylene-polysiloxane block copolymers of the general average formula I whereR1 and/or R7 are R2 or â€”[R4]wâ€”[R5]xâ€”R6â€”R8, R2 and R3 are identical or different alkyl radicals or are unsubstituted or substituted aryl radicals, R4 is a divalent radical of the formula â€”Oâ€”, â€”NHâ€”, â€”NR2â€”, â€”Sâ€” or of the formula â€”[Oâ€”Si(CH3)2]uâ€”, â€ƒwhere u is from 2 to 200, R5 is identical or different alkylene radicals having 1 to 24 carbon atoms, or is â€”CnH2n-fR2fâ€”Oâ€”CmH2m-gR2gâ€”, â€ƒwhere f is from 0to 12, g is from 0to 12, n is from 1 to 18, m is from 1 to 18, R6 is identical or different radicals of the general formula â€”Oâ€”(C2H4-aR9aO)b(CH2â€”CH2â€”CH2â€”CH2-cR10cO)dâ€”â€ƒwhere, R9 is identical or different alkyl radicals, R10 is an alkyl radical, but where, taking into account all radicals R6, the proportion of C2H4O groups among the total of all radicals R6 does not exceed 40% by weight a is from 0 to 3, b is from 0 to 200, c is from 0 to 2, d is from 2 to 40, the sum (b+d)=3 to 240 and the sequence of the individual polyoxyalkylene segments â€”(C2H4-aR9aO)bâ€” and â€”(CH2â€”CH2â€”CH2â€”CH2-cR10cO)dâ€” and is either random or block or combinations thereof, R8 is a hydrogen, a substituted or unsubstituted alkyl radical, or an acyl radical, v is from 3 to 200, w is 0 or 1, x is 0 or 1, y is from 0 to 200, and, if y is 0, R1 and/or R7 are/is â€”[R4]wâ€”[R5]xâ€”R6â€”R8.