Dow Corning Corporation

Rick D Streu

David Joseph Romenesko

Roland L Halm

Eugene D Groenhof

Regie H Zapp

The present invention provides a method for reducing the concentration of methyltrichlorosilane obtained during the reaction of silicon metal with methyl chloride without substantially decreasing the combined yield of methyldichlorosilane, dimethylchlorosilane and dimethyldichlorosilane. The methyl chloride is blended with from 0.05 up to about 44 mole percent of hydrogen, based on combination of methyl chloride and hydrogen. At hydrogen concentrations above about 12 mole percent there is a substantial increase in the methyldichlorosilane content of the reaction product while the concentration of methyltrichlorosilane in the reaction product is maintained below about 4 percent by weight.

Method for preparing organohalosilanes

A random siloxane copolymer composition, and a process for using the composition in a hydraulic brake system of a vehicle, is described. The random copolymer consists essentially of alkylmethylsiloxane and dimethylsiloxane units, wherein said alkyl group contains from five to ten carbon atoms, and the viscosity of said fluid is 15-50 cS at 25.degree. C. Within a relatively narrow compositional range, these fluids dissolve at least 15% less air than comparable polydimethylsiloxane fluids. Moreover, the copolymer may be readily formulated into brake fluid compositions which meet Department of Transportation (DOT 5) and, in the case of preferred compositions, Military (MIL-B-46176) specifications. The potential benefit of reduced air solubility is an improved margin of safety under harsh driving conditions.

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Midland, MI, United States of America

Rick D Streu