Abstract: Disclosed is a silicone-based antifoam composition capable of exhibiting high defoaming activity even at a high temperature with excellent durability so as to be useful in dyeing processes. The composition comprises, as the principal ingredient, a polyoxyalkylene-modified polydimethylsiloxane, of which, different from conventional polyoxyalkylene-modified polydimethylsiloxanes, the polyoxyalkylene groups consist of two different types relative to the molar proportion of the oxyethylene units and oxypropylene units, in addition to a silicone oil compound of a silica filler, a poly(oxyethylene-oxypropylene) copolymer and low-molecular polydimethylsiloxane terminated at each molecular chain end with a dimethyl hydroxy silyl group.

Abstract: A defoamer composition comprising (A) an organopolysiloxane containing an oxyalkylene group having an appropriate hydrophilic-hydrophobic balance, (B) another organopolysiloxane containing an oxyalkylene group serving as a surface active agent for component (C), (C) a dimethylpolysiloxane for retaining defoaming power, and (D) a silica filler can maintain defoaming power for a long time, for example, when it is added to a developer for exposed photosensitive resin which is subject to shearing stresses in the wash-out step.

Abstract: An organopolysiloxane containing at least one epoxy group is produced by heating a mixture of (a) an epoxy group-containing organosiloxane; (b) an organosiloxane lacking an epoxy group and optionally containing an arkenyl group; (c) an aprotic polar organic solvent; and (d) a basic catalyst, until reaction between (a) and (b) by a disproportionation equilibration reaction occurs.

Abstract: A fine powder of an epoxy-containing silicone elastomer can be made by:(i) dispersing in water a hardenable organopolysiloxane compound composed of(A) an organopolysiloxane of 20-100,000 cS at 25.degree. ##STR1## (R's are the same or different unsubstituted or substituted hydrocarbon groups containing no unsaturated bond; subscripts a and b are integers selected from 0, 1, 2 and 3 such that a+b=3; x is a positive integer; y is 0 or a positive integer such that 2b+y.gtoreq.2);(B) an organohydrogenpolysiloxane containing, in a molecule, at least two hydrogen atoms bonded to silicon and at least one epoxy-bearing organic group bonded to silicon ##EQU1## (R is the same as above; A is an epoxy-bearing organic group; c is a number from 0 to 3, and d and e are numbers from 0.005 to 2.0 such that 0.8<c+d+e<3);(C) a Pt-containing catalyst;(ii) hardening the particles dispersed in the aqueous emulsion to thereby obtain a silicone elastomer emulsion of particles having a mean diameter of 20 .mu.

Abstract: 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.

Abstract: A silicone emulsion composition, comprising:(A) 100 parts by weight of a silicone oil compound essentially consisting of from 70 to 99% by weight of an organopolysiloxane and from 30 to 1% by weight of finely powdered silica; and(B) from 3 to 40 parts by weight of a mixed emulsifying agent having an HLB of from 7.0 to 8.5, consisting of (B-1) from 50 to 75% by weight of a sorbitan fatty acid ester with an HLB of from 2.0 to 6.5, (B-2) from 5 to 40% by weight of polyoxyethylene sorbitan fatty acid ester with an HLB of from 6.0 to 16.0, and (B-3) from 5 to 30 parts by weight of a compound selected from the group consisting of a polyoxyethylene higher alcohol ether and a polyoxyethylene alkylphenol ether, each having an HLB of from 12.0 to 19.5. This emulsion has a low viscosity, good dilution property and good stability.

Abstract: 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.

Abstract: 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.

Abstract: The silicone-based antifoam composition having excellent durability of the antifoam activity even under vigorous agitation or under an alkaline condition comprises three kinds of diorganopolysiloxanes, of which the first is free from aliphatic unsaturation, the second is terminated at both molecular chain ends each with a vinyl diorganosilyl group and the third is terminated at both molecular chain ends each with a diorganosilyl group having a silicon-bonded hydrogen atom, a finely divided silica powder, a platinum compound to catalyze the addition reaction between the silicon-bonded vinyl groups and silicon-bonded hydrogen atoms in the second and the third diorganopolysiloxanes, respectively, and an organosilane compound of the formula R.sup.1.sub.a Y.sub.b Si, in which R.sup.1 is a monovalent hydrocarbon group, Y is a hydroxy, carboxyl or hydrolyzable group and a and b are each 1, 2 or 3 with the proviso that a+b=4.

Abstract: The antifoam composition provided by the invention comprises (a) 100 parts by weight of a hydrocarbon oil, e.g. spindle oil, or a silicone fluid, e.g. polydimethylsiloxane fluid, having a viscosity of 20 to 1,000,000 centistokes at 25.degree. C., (b) 0.1 to 40 parts by weight of an organosilane compound having 1 to 3 hydroxy groups or hydrolyzable groups, e.g. alkoxy, acyloxy and alkenyloxy groups, (c) 1 to 40 parts by weight of a finely divided silica powder and, optionally, (d) up to 5 parts by weight of a catalyst. The antifoam composition can exhibit excellent and durable defoaming activity even under vigorous agitation or in an alkaline condition of the foaming liquid.

Abstract: The self-emulsifiable silicone composition of the invention comprises (a) an organopolysiloxane having polyoxyalkylene moieties and perfluoroalkyl-containing organic groups and represented by the average unit formula ##STR1## in which R is hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms, G is polyoxyalkylene residue represented by the general formula ##STR2## and (b) an organopolysiloxane having perfluoroalkyl-containing organic groups represented by the average unit formula ##STR3## The composition is useful as an antifoam agent and, despite the high self-emulsifiability and stability, exhibits excellent defoaming activity even at relatively low temperatures around room temperature in contrast to conventional silicone-based antifoam compositions.

Abstract: A very simple and versatile method is proposed for the preparation of an aqueous emulsion of silicone in which an organochlorosilane or a mixture of organochlorosilanes is added dropwise into an aqueous medium in the presence of a surface active agent or, preferably, into an aqueous medium containing a surface active agent in advance followed by or with concurrent removal of the hydrogen chloride from the mixture by adding an alkaline neutralizing agent or by use of the techniques of ion exchange so that a stable aqueous emulsion can be produced in the aqueous medium at the same time as the organochlorosilane or silanes are hydrolyzed followed by the dehydration condensation of the resultant silanol compounds to form an organopolysiloxane in situ by the catalytic activity of the hydrogen chloride formed by the hydrolysis.