Patent ID: 8257674
Filing Date: 2012-09-04
Classification: B82Y,C01B,C01P,C04B,C09C,C09K,Y10T

Abstract:
1. Non-silylated fumed silica particles having a thickening action η rel greater than 3.5, when measured in liquid polydimethylsiloxane with a viscosity of 1 Pas at a temperature of 25° C. and measured at a shear rate of 10 s −1 , and which, in dry form, are capable of forming accumulations with a porosity ε of >0.5, the fumed silica particles prepared by the reaction of a mixture of silanes comprising tetrachlorosilane and hydrotrichlorosilane in a hydrogen-oxygen flame at temperatures of greater than 1000° C. and up to a maximum of 2000° C. with the proviso that the fumed silica particles are produced under anhydrous conditions and following the reaction, the fumed silica particles are separated from process gas and subsequently purified to free them of residual hydrogen chloride gas, which is effected in a hot gas stream, at temperatures of ≧250° C. to 600° C.