PROCEDE D'OBTENTION DE POLYSILOXANES DE MASSES MOLECULAIRES ELEVEES PAR POLYMERISATION ET REARRANGEMENT DE POLYSILOXANES EN PRESENCE DE CATALYSEUR CONSTITUE PAR UN SUPPORT MINERAL POREUX RECOUVERT D'UN FILM POLYMERIQUE PORTEUR DE GROUPEMENT SULFONIQUE OU PHOSPHONIQUE

摘要

Polysiloxanes of relatively low molecular weight are catalytically polymerized/rearranged into high molecular weight polysiloxanes in the presence of a cationic catalyst comprising a porous, inorganic mineral particulate support having an average pore diameter in excess of 20 ANGSTROM and a pore volume ranging from 0.2 to 2 ml/g, said porous support being coated with less than 15 mg/m2 of a film of polymeric material comprising pendant sulfonic or phosphonic acid functions, and said polymeric material being characterized by an ion exchange capacity of less than 2 milliequivalents per gram.