Process for the recovery of methyl polysiloxanes in the form of cyclosiloxanes

Abstract

A process for the recovery of methyl polysiloxane in the form of methyl cyclosiloxane of the general formula (R2SiO)x, wherein R is selected from alkyl, alkenyl, aryl and alkaryl groups and “x” is an integer selected from 3-6, in which: a) liquifying silicone feedstock as herein defined is liquefied in a solvent selected from alcohol or siloxane in presence of a catalyst at a temperature of between 110° C.-180° C. to obtain a liquefied mass consisting of a mixture of methyl polysiloxane, solvent and filler; b) adding a metal hydroxide to the liquefied mass so as to convent the fillers to their corresponding silicates, the said silicates thus obtained are removed and the liquid recovered; and c) cyclyzing methyl polysiloxane in the liquid medium thus obtained in the presence of a cracking catalyst in the temperature range of 115-160° C. so as to crack the liquid methyl polysiloxane to a mixture of volatile methyl cyclosiloxane. The process may be used to recover methyl cyclosiloxane from silicone containing scrap material.

Dependencies are inferred from the claim text.