GB1513310A - Organopolysiloxanes - Google Patents

Abstract

1513310 Organopolysiloxanes; polycarbonate compositions GENERAL ELECTRIC CO 7 Aug 1975 [16 Sept 1974] 32986/75 Headings C3T and C3R A phenyl-containing organopolysiloxane fluid of the general formula wherein Ph is phenyl, R is hydrogen, trimethylsilyl or a mixture thereof, and wherein x and y have a combined value sufficient to provide a phenyl content of from 7-80 weight per cent is made by the solvent hydrolysis of diphenyldichlorosilane and dimethyldichlorosilane generally in a weight ratio of from 1À5 : 1 to 4 : 1. Suitable solvents are benzene, toluene, xylene, esters and ethers. The mixture of organochloro silanes in an organic solvent is mixed with and agitated in preheated water. The resulting organic layer is separated from the aqueous layer and water removed azeotropically therefrom. The resulting hydrolyzate is saturated with anhydrous ammonia and trimethylchlorosilane added thereto generally in an amount of 9À5-25À5 wt. per cent based on the weight of the hydrolyzate. The resulting organic layer is separated and the water and solvent stripped therefrom to yield an organopolysiloxane fluid (A) of the above formula wherein R is a mixture of H and trimethylsilyl. A fluid in which R is substantially all trimethylsilyl may be obtained by employing a sufficient amount of trimethylchlorosilane in the above hydrolysis reaction. The resulting all trimethylsiloxy-chain stopped fluid may then be equilibrated in the presence of KOH and optionally with the addition of further trimethylsiloxy chain-stopping units. The resulting fluid has a phenyl content of 40-80 wt. per cent and is one wherein x = 3-10 and y = 3-10 in the above formula. Alternatively the above equilibration may be carried out with the addition of octamethylcyclotetrasiloxane and trimethylsiloxy containing units provided by, e.g. linear decamethyltetrasiloxane, resulting in a fluid of viscosity 100-200 cS at 25‹ C. and a phenyl content of 30-48 wt. per cent. In another embodiment organopolysiloxane fluid (A) above is modified by adding thereto octamethylcyclotetrasiloxane in an amount sufficient to lower the phenyl content to 30% wt. and then equilibrating. The organopolysiloxane fluids preferably those in which R is a mixture of hydrogen and trimethylsilyl, the phenyl content is 40-80 wt. per cent and the trimethylsiloxy unit content is 12-21 wt. per cent can be added as mould release agents to polycarbonates generally in an amount of from 0À01 to 2À0 wt. per cent based on the polycarbonate. The preferably polycarbonate is the reaction product of phosgene and 2,2-bis(4-hydroxyphenyl)propane. Other uses of the fluid include mechanical and hydraulic fluids; high temperature grease components and transparent and controlled density greases.