Patent ID: 7655811
Filing Date: 2010-02-02
Classification: C08G

Abstract:
1. A process for preparing organohydropolysiloxanes (P) bearing two terminal silicon-bonded OH groups, comprising reacting, in a first step, organohydrodichlorosilanes (A) and diorganodichlorosilanes (B) with at most 0.5 mol of water per mol of hydrolyzable chlorine to give a partial hydrolyzate (T) and gaseous hydrogen chloride, and, in a second step, treating the partial hydrolyzate (T) with water to hydrolyze the SiCl groups still present, to form hydrochloric acid, and separating a hydrolyzate (H) comprising the organohydropolysiloxanes (P), wherein the hydrolyzate (H) obtained after the second step is separated into organohydropolysiloxanes (P) and a mixture (G) comprising volatile organopolysiloxanes, and the mixture (G) is removed by distillation which is carried out in two stages in which mixtures (G 1 ) and (G 2 ) are obtained and at least one of (G 1 ) or (G 2 ) is recycled into the first step and/or second step or entirely or partly rearranged to less volatile, substantially linear organopolysiloxanes.