Patent ID: 6391831
Filing Date: 2002-05-21
Classification: B01D,C08G,C11D

Abstract:
A method for defoaming aqueous media which comprises adding to the aqueous media a defoamer comprising a water-insoluble polyoxyarylene-polysiloxane block copolymer of the general average formula 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, or is â€”CnH2nâˆ’fR2fâ€”Oâ€”CmH2mâˆ’gR2gâ€”, â€ƒwhere f is from 0 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€”(C2H4âˆ’aR9aO)b(C2H4âˆ’aR10aO)câ€”, â€ƒwhere R9 is identical or different alkyl radicals and R10 is a radical of the general formula II â€ƒbut 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, and wherein at least one R10 is present, and R11 can be identical or different and is a hydrogen, a hydrocarbon radical or a halogen atom, a is individually from 0 to 3, b is from 0 to 100, c is from 1 to 100, and the sum (b+c) is from 3 to 200 â€ƒand the sequence of the individual polyoxyalkylene and/or polyoxyarylene segments â€”(C2H4âˆ’aR9aO)bâ€” and â€”(C2H4âˆ’aR10aO)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.