Abstract: A heat-curable silicone rubber composition whose cure provides silicone rubber with excellent high-voltage electrical insulating properties. The heat-curable silicone rubber composition comprises:(A) polyorganosiloxane gum described by average compositional formulaR.sub.a SiO.sub.(4-a)/2,where R represents substituted and unsubstituted monovalent hydrocarbon groups and a is a number from 1.95 to 2.05 and that contains at least 2 silicon-bonded alkenyl groups in each molecule,(B) microparticulate silica,(C) zinc carbonate powder or basic zinc carbonate powder, and(D) organoperoxide.

Abstract: A liquid silicone rubber composition that prior to its cure has a suitable fluidity and excellent moldability and that cures into a highly flame retardant silicone rubber molding with excellent electrical properties. The liquid silicone rubber composition comprises(A) polyorganosiloxane,(B) microparticulate silica,(C) aluminum hydroxide powder,(D) zinc carbonate powder,(E) polyorganohydrogensiloxane,(F) benzotriazole,(G) the reaction mixture of(a) a platinum compound and(b) 3,5-dimethyl-1-hexyn-3-ol, and(H) hydrosilylation reaction catalyst.

Abstract: A silicone rubber composition having improved mold release properties comprising (A) silicone rubber base compound, (B) organopolysiloxane having no aliphatic unsaturated groups, (C) higher fatty acid or higher fatty acid metal salt, (D) water, and (E) curing agent.

Abstract: A high-consistency organosiloxane composition comprising fluorinated and non-fluorinated polyorganosiloxanes, which upon the addition of suitable cure components can be cured to form elastomers having improved tear strength and good resistance to hydrocarbon oil weep. The present composition comprises a reinforcing silica filler that has been treated with a tetraalkyldisilazane.

Abstract: A process for separating an emulsion into separate and easily recoverable phases. The process comprises exposing an emulsion comprising a discontinuous phase and a non-conducting continuous phase to an electric field thereby effecting coalescence of the discontinuous phase into droplets of a size for effective gravitation from the continuous phase, where the discontinuous phase and the continuous phase have different dielectric constants and densities and at least one of the phases comprise a silicon containing compound or a silicon containing polymer. The present process is especially useful for separating emulsions where the discontinuous phase is an aqueous acid solution and the continuous phase is diorganopolysiloxane.

Abstract: A highly productive, continuous method for the production of room-temperature-curable organopolysiloxane compositions is obtained by continuously feeding 100 parts by weight of a diorganopolysiloxane with a viscosity at 25.degree. C. of 0.1 to 500 Pa.

Abstract: A platinum curing organosiloxane composition having improved hysteresis characteristics when cured. The composition requires the presence of a diorganovinylsiloxy terminated polydiorganosiloxane having a viscosity within a range of about 20 Pa.multidot.s to 200 Pa.multidot.s at 25.degree. C. and containing essentially no ethylenically unsaturated hydrocarbon radicals bonded to non-terminal silicon atoms and a diorganovinylsiloxy terminated polydiorganosiloxane having a viscosity within a range of about 0.1 Pa.multidot.s to 200 Pa.multidot.s at 25.degree. C., where from 1 to 5 percent of the non-terminal repeating units of the siloxane comprise a vinyl radical. In addition, the present composition comprises 10 to 30 weight percent of a reinforcing silica filler that has been treated with hexamethyldisilazane and 1,1,3,3-tetramethyl-1,3-divinyldisilazane, and an organohydrogensiloxane resin crosslinker comprising greater than 5 silicon-bonded hydrogen atoms per molecule.

Abstract: A platinum group-metal curing liquid silicone rubber compositions having improved physical properties such as tear and heat-aging, especially at durometers below about 35 and above about 65. The present inventors have unexpectedly discovered that the addition of diorganohydrogensiloxy end-blocked polydiorganosiloxanes and triorganosiloxy end-blocked polydiorganosiloxanes having a viscosity greater than about 10 Pa.cndot.s at 25.degree. C. to liquid silicone rubber compositions can provide for the described improved properties.

Abstract: The present invention is a curable fluorosilicone composition having improved lubricity, low compression set, and good resistance to fluids such as automotive fuel without post-curing. The composition comprises(A) poly(trifluoropropyl)methylsiloxane, (B) vinylmethyldi(N-alkylacetamido)silane, (C) reinforcing treated silica, (D) chlorotrifluoroethylene polymer, and (E) vinyl specific organic peroxide catalyst.

Abstract: A method for purifying 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropyl methyldihalosilanes which is characterized by the fact that 1-methyl-2-methacryloxyethyldimethyl halosilanes or 1-methyl-2-methacryloxyethylmethyldihalosilanes contained in products or fractions consisting of 3-methacryloxypropyldimethylhalosilanes or 3-methacryloxypropylmethyl dihalosilanes produced by a hydrosilation reaction of allyl methacrylate with dimethylhalosilanes or methyldihalosilanes are decomposed by means of at least one copper compound selected from the group consisting of copper hydroxides, copper salts other than copper halides, and copper oxides, after which these compounds are subjected to fractional distillation.

Abstract: A method for separating hexamethylcyclotrisiloxane that does not require the use of a distillation set up adapted for use with solids and that collects the hexamethylcyclotrisiloxane in the form of an easy-to-handle solution. The method comprising inducing the ascent in the gaseous state of a hexamethylcyclotrisiloxane-containing mixture of polydimethylcyclosiloxanes in a distillation column provided with a sidestream element in the middle region of the column so as to induce the ascent of gaseous hexamethylcyclotrisiloxane to at least the level of the sidestream element, supplying into said distillation column solvent having a boiling point below that of hexamethylcyclotrisiloxane and capable of dissolving hexamethylcyclotrisiloxane, so as to form a liquid mixture of hexamethylcyclotrisiloxane and said solvent in the vicinity of the sidestream element, and withdrawing the said liquid mixture from the sidestream element.

Abstract: The present invention is silicone rubber compositions the exhibit high mechanical strength and excellent electrical properties such as tracking resistance, arc resistance, and erosion resistance. The improved properties are obtained by incorporation in the compositions aluminum hydroxide powder which has been treated with a treating agent selected from the group consisting of silanes and siloxanes having alkenyl and alkoxy or hydroxy substitution.

Abstract: The present fluorosilicone rubber composition cures to give fluorosilicone rubber moldings with excellent physical properties. The fluorosilicone rubber composition comprises:(A) a 3,3,3-trifluoropropylmethylsiloxane-methylvinylsiloxane copolymer gum,(B) a dimethylsiloxane-methylvinylsiloxane copolymer gum,(C) a poly(3,3,3-trifluoropropylmethylsiloxane)-polydimethylsiloxane block copolymer or (C-2) a poly(3,3,3-trifluoropropylmethylsiloxane)-polydimethylsiloxane-polymethylv inylsiloxane block copolymer,(D) a reinforcing silica micropowder that has a surface area of at least 50 m.sup.2 /g, and(E) a curing agent.

Abstract: A method for purifying 3-methacryloxypropyl-dimethylhalosilane or 3-methacryloxypropylmethyldihalosilane comprising adding (A) a Lewis acid halide to (B) 3-methacryloxypropyldimethylhalosilane or 3-methacryloxypropyl-methyldihalosilane obtained from an addition reaction of (a) allyl methacrylate and (b) dimethylhalosilane or methyldihalosilane, where the addition reaction by-products contained in aforementioned component (B), 1-methyl-2-methacryloxyethyldimethylhalosilane or 1-methyl-2-methacryloxyethylmethyldihalosilane, are decomposed and the decomposition products produced are then separated by distillation.

Abstract: The present invention is neutral-aged hydrophobic organosilicate-modified silica gels and a method for their preparation. The method comprises three steps, where in the first step an organosilicate-modified silica hydrosol is contacted with a strong mineral acid at a pH less than about 1 to form an organosilicate-modified silica hydrogel. In the second step the organosilicate-modified silica hydrogel is aged at a pH within a range of about pH 3.5 to pH 8. In the third step the neutral-aged organosilicate-modified silica hydrogel is contacted with an organosilicon compound in the presence of a catalytic amount of a strong acid to effect hydrophobing of the organosilicate-modified silica hydrogel to form a hydrophobic organosilicate-modified silica hydrogel having a surface area within a range of about 100 m.sup.2 /g to 750 m.sup.2 /g in the dry state.

Abstract: An method for the synthesis of high-purity (meth)acryloxy-functional organosilicon compounds in which the generation of reaction by-products is inhibited and gelation of the reaction product does not occur comprising an addition reaction between(A) an acrylate ester or methacrylate ester of an aliphatically unsaturated alcohol and(B) a SiH-functional organosilicon compound in the presence of(C) a hydrosilylation-reaction catalyst and(D) a special type of compound such as the zinc salt of 2-mercaptobenzothiazole or zinc dimethyldithiocarbamate.

Abstract: The present invention is hydrophobic organosilicate-modified silica gels and a method for their preparation under neutral conditions. The method comprises two steps, where in the first step the pH of an organosilicate-modified silica hydrosol is adjusted with a base to within a range of about pH 3 to pH 7 to facilitate formation of an organosilicate-modified silica hydrogel. In the second step the organosilicate-modified silica hydrogel is contacted with an organosilicon compound in the presence of a catalytic amount of a strong acid to effect hydrophobing of the organosilicate-modified silica hydrogel to form a hydrophobic organosilicate-modified silica gel having a surface area within a range of about 100 m.sup.2 /g to 850 m.sup.2 /g in the dry state.

Abstract: A method for neutralizing a polyorganosiloxane mixture. The method comprises (A) contacting a mixture comprising a polyorganosiloxane and an acid with a neutralizing amount of a solid organic base at a mixture temperature above the melting temperature of the solid organic base forming a molten organic base and forming an insoluble adduct of the acid with the molten organic base, (B) lowering the mixture temperature to effect solidification of residual molten organic base to residual solid organic base, and (C) effecting separation of the insoluble adduct and the residual solid organic base from the polyorganosiloxane mixture. The present invention is especially useful for neutralizing mixtures comprising polyorganosiloxane mixtures where the polyorganosiloxane comprises hydrogen atoms bonded to silicon.

Abstract: A method for the preparation of one-package room-temperature-curable silicone compositions that do not slump prior to their cure, do not crack or fissure during their cure even when deformed by an external force, and do not yellow where an example of the room-temperature-curable silicone compositions is(a) hydroxyl-terminated diorganopolysiloxane,(b) oxime-functional organosilicon compound, and(c) inorganic filleraccording to the following four steps:step (1) in which 20 to 70 weight % of the total amount of component (a) is mixed with methyltris(methyl ethyl ketoximo)silane,step (2) in which component (c) is added and mixed into the mixture prepared in step (1),step (3) in which 30 to 80 weight % of the total amount of component (a) is mixed with vinyltris(methyl ethyl ketoximo)-silane,step (4) in which the mixture prepared in step (3) is mixed with the mixture prepared in step (2).

Abstract: A method for the preparation of hydrophobic silica gels which are useful as reinforcing fillers in rubber compositions. The method comprises two steps, where in the first step a silica hydrosol is contacted with a sufficient concentration of a strong mineral acid at a pH less than about pH 1 to form a silica hydrogel. In the second step the silica hydrogel is contacted with described organosilicon compounds in the presence of a catalytic amount of a strong acid to effect hydrophobing of the silica hydrogel thereby forming a hydrophobic silica gel having a surface area within a range of about 100 m.sup.2 /g to 750 m.sup.2 /g as measured in the dry state. In a preferred method the hydrophobic silica hydrogel is contacted with a sufficient quantity of a water-immiscible organic solvent to convert the hydrophobic silica hydrogel into a hydrophobic silica organogel.