Patent ID: 6433028
Filing Date: 2002-08-13
Classification: B01D

Abstract:
A method for defoaming aqueous media which comprises adding to the aqueous media a defoamer comprising a water-insoluble 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€”, where 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 to 12, g is from 0 to 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€”(C2H4O)a(CH2â€”CH(CH3)O)b(CH2â€”CR9R10O)câ€”, â€ƒwhere R9 and R10 are a methyl radical, or R9 is a hydrogen atom and R10 is an ethyl 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 2 to 30, b is from 2 to 50, c is from 2 to 40, and the sum (a+b+c) is from 6 to 100 and the sequence of the individual polyoxyalkylene segments â€”(C2H4O)aâ€” and â€”(CH2â€”CH(CH3)O)bâ€” and â€”(CH2CR9R10O)câ€” is either random or block or combination 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.