Production of polydiorganosiloxanes from a diorganodichlorosilane comprises a three stage process in which water is recycled at each stage

摘要

Process for the production of polydiorganosiloxanes comprises formation of a crude hydrolysate from a diorganodichlorosilane and reduction of the chlorine content by contact with steam in a three stage process with recycling of the waste water at each stage. A process for the production of polydiorganosiloxanes (I) comprises (A) reaction of a diorganodichlorosilane with water containing hydrochloric acid to a form a crude hydrolysate, consisting of cyclic and linear, chlorine containing polydiorganosiloxanes and gaseous hydrogen chloride. (B) reduction of the chlorine content of the crude hydrolysate by treatment with steam to form hydrochloric acid, whereby the resulting hydrochloric acid is used in step (A) and (C) further reduction of the chlorine content of the crude hydrolysate with steam to form a hydrochloric acid and polydiogranosiloxane containing acidic water whereby the acidic water is separated to form an acid containing and acid free water and the acid containing water is evaporated and used in step (B).