Production of polydiorganosiloxane fluids with low silanol content

Abstract From the Canadian patent

A continuous process for producing a triorganosilyl end-blocked polydiorganosiloxane fluid with reduced silanol content and reduced branching content is described. The process comprises (a) feeding to a series of two columns packed with an acid-treated clay a liquid siloxane feed mixture, containing as a major portion a polydiorganosiloxane monomer and as a minor portion a triorganosilyl end-blocking material; (b) contacting the liquid siloxane feed mixture with the acid-treated clay in the first and second packed columns, respectively, at a temperature in a range from about 100° to 150°C. at a pressure in a range from about 5 to 1520 mm Hg at a contact time of less than about 15 minutes; …