Silicone grease composition and method for preparing same
AssigneeDow Corning Toray Silicone Co., Ltd.
InventorsKiyotaka Sawa, Yasushi Sugiura, Osamu Tanaka
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Abstract
Silicone grease compositions are prepared by blending a thickening agent with a liquified crosslinked organosiloxane gel produced using a platinum-catalyzed hydrosilylation reaction. The gel is liquified by application of a shearing force to the crosslinked gel. The shearing force can be applied prior to and/or during blending of the gel with the thickener.
Claims8
A silicone grease composition consisting essentially of the product obtained by blending under shear
- (I) a liquified crosslinked organosiloxane gel obtained by curing a composition comprising
- (a) an organopolysiloxane containing at least two silicon-bonded lower alkenyl radicals per molecule,
- (b) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, where the quantity of said organohydrogenpolysiloxane provides from 0.3 to 1.1 silicon-bonded hydrogen atoms per lower alkenyl radical present in said organopolysiloxane, and
- (c) a hydrosilation reaction catalyst and
- (II) a thickener selected from the group consisting of fumed silica, hydrophobicized fumed silica, precipitated silica, hydrophobicized precipitated silica, fused silica, finely divided quartz, diatomaceous earth, talc, calcium carbonate, zinc oxide, titanium dioxide, ferric oxide, glass fiber, glass beads, glass balloons, alumina, silicon carbide, nitrogen carbide, aluminum nitride, boron nitride, manganese carbonate, carbon black, graphite, cerium hydroxide, and powdered polytetrafluoroethylene, where the oil bleed from said grease composition is equivalent to less than 1 percent by weight of the composition.
A method of preparing a silicone grease composition exhibiting an oil bleed equivalent to less than 1 percent by weight of said composition, said method comprising blending to homogeneity a mixture comprising
- (I) a liquified crosslinked organasiloxane gel obtained by the reaction of
- (a) an organopolysiloxane having at least two silicone-bonded lower alkenyl radicals in each molecule,
- (b) an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms in each molecule, the concentration of said organohydrogenpolysiloxane being equivalent to from 0.3 to 1.1 silicon-bonded hydrogen atoms per lower alkenyl radical in said organopolysiloxane, and
- (c) a quantity of a hydrosilylation reaction catalyst sufficient to cure said composition to a crosslinked gel, and
- (II) a thickener selected from the group consisting of fumed silica, hydrophobicized fumed silica, precipitated silica, hydrophobicized precipitated silica, fused silica, finely divided quartz, diatomaceous earth, talc, calcium carbonate, zinc oxide, titanium dioxide, ferric oxide, glass fiber, glass beads, glass balloons, alumina, silicon carbide, nitrogen carbide, aluminum nitride, boron nitride, manganese carbonate, carbon black, graphite, cerium hydroxide, and powdered polytetrafluoroethylene;
- where the shearing force applied during blending of said gel with said thickener is sufficient to liquify said gel.
Dependencies are inferred from the claim text.