Patent ID: 8076438
Filing Date: 2011-12-13
Classification: C08G

Abstract:
1. A process for the preparation of organopolysiloxanes, comprising partially hydrolyzing and then further hydrolyzing chlorosilanes by sequential first and second steps consisting of: in a first continuous step, partially hydrolyzing chlorosilanes by reacting chlorosilanes and optionally an alkoxysilane in a loop reactor with natural circulation with a liquid component consisting essentially of water and alcohol, containing from 0.002 to 0.6 mol of water per mole of hydrolyzable chlorine and from 0.3 to 1.6 mol of alcohol per mol of hydrolyzable chlorine to form an Si component which is a partial hydrolysate, the molar ratio of water to alcohol being from 0.001 to 1.5, wherein gaseous HCl is generated and withdrawn as a gas from the loop reactor during the first step, in the second step, further hydrolyzing the partial hydrolysate of the first step by introducing the partial hydrolysate of the first step from the loop reactor into a batch reactor and metering into the batch reactor a chlorosilane hydrolysis component consisting essentially of water and optionally alcohol, in an amount of from 0.2 to 100 mol of water per mol of Si component wherein the reaction mixture obtained in the first step is optionally mixed with a water-insoluble organic solvent having a density of less than 0.9 kg/l, wherein one or more chlorosilanes and/or one or more alkoxysilanes are optionally added in the second step, wherein in the second step, the water of the chlorosilane hydrolysis component hydrolyzes and condenses the Si component to an organopolysiloxane product, and in a third step, forming a two phase mixture comprising an aqueous alcoholic liquid phase and an organopolysiloxane phase containing the organopolysiloxane product, and separating the aqueous alcoholic liquid phase from the organopolysiloxane phase containing the organopolysiloxane product in a liquid/liquid separation.