PROCESS FOR PREPARING HIGH-MOLECULAR WEIGHT POLYSILOXANES BY POLYMERIZATION AND REARRANGEMENT IN THE PRESENCE OF A CATALYST WHICH IS A MINERAL POROUS SUPPORT COVERED WITH A POLYMER FILM HAVING SULPHONIC OR PHOSPHONIC GROUPS

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.