Shin-etsu Chemical Co., Ltd.

Teiichi Mutoh

Masaki Tanaka

Nobuyuki Terae

Akira Yoshida

Noriyuki Meguriya

Eiichi Tabei

An organopolysiloxane emulsion composition comprising:

Organopolysiloxane emulsion composition

The silicone-based defoaming composition of the invention comprises (a) a polyoxyalkylene group-substituted organopolysiloxane, (b) a dimethyl silicone fluid and (c) a finely divided silica powder. Different from conventional similar compositions, the polyoxyalkylene groups in the component (a) are bonded to the silicon atoms only in the monofunctional siloxy groups and the component (a) necessarily has trifunctional siloxane units. By virtue of this unique formulation, the inventive defoaming composition added to a foaming liquid is very stable against flocculation even at a high temperature and even in the presence of an inorganic salt in a high concentration in the foaming liquid, e.g., dyeing bath.

Defoaming composition

Perfluoroalkyl group containing organopolysiloxanes having a high degree of polymerization can be prepared by reacting a liquid organopolysiloxane of formula (I): R.sup.1.sub.aR.sup.2.sub.b (OH).sub.c SiO.sub.[4.(a+b+c)]/2 with an alkali metal hydroxide to form an alkali metal silanolate; reacting the alkali metal silanolate with a perfluoroalkyl group-containing organosilane of formula (II): RfR.sup.3 SiX.sub.2 to synthesize a perfluoroalkyl group-containing organopolysiloxane intermediate of formula (III): [(R.sup.1.sub.a R.sup.2.sub.b SiO).sub.m (RfR.sup.3 SiO)].sub.n ; and polymerizing the intermediate of formula (III) or a mixture of the intermediate and an organopolysiloxane of formula (IV): R.sup.5.sub.e R.sup.6.sub.g SiO.sub.[(4.(e+g)]/2 in the presence of a strongly acidic catalyst or strongly basic catalyst.

Method for preparing perfluoroalkyl group-containing organopolysiloxanes

An antifoamer which comprises a polyperfluoroether group-containing organopolysiloxane comprising from 20 to 100 mole % of the polyperfluoroether group-containing organopolysiloxane units of a specific type is described. The content of fluorine atoms in the polyperfluoroether group-containing organopolysiloxane is in the range of from 20 to 70 wt % by which foams of organic solvent systems can be inhibited to a substantial extent.

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Annaka, Japan

Teiichi Mutoh