Production of polyorganosiloxanes, e.g. oils or gums, by ring-opening polymerization or rearrangement of other polyorganosiloxanes using carbene as catalyst effective at low temperature

摘要

Production of polyorganosiloxanes (A) by ring-opening polymerization or rearrangement of other polyorganosiloxanes (B) is carried out using a catalyst (I) comprising at least one carbene. Independent claims are included for: (1) compositions for the preparation of (A) as above, comprising one or more linear, branched and/or cyclic starting compounds (B), a catalyst (C) (excluding metal-carbene complexes), optionally solvent(s) and optionally linear polyorganosiloxanes (e.g. polydialkyl siloxanes of degree of polymerization up to 20, preferable disiloxanes such as hexamethyl disiloxane or its vinylated or hydrogenated analog); (2) silicone compositions containing (A), obtained by polymerization and/or rearrangement of (B), and residues of the catalysts (C); (3) silicone compositions containing (A), obtained by ring-opening polymerization and/or rearrangement of (B) (especially cyclic (B)), having a final acyclic to cyclic polyorganosiloxane ratio of more than 85/15 (especially more than 95/5); (4) new polyorganosiloxanes (D) substituted by catalytic functions suitable for generating carbenes; (5) new silanes of formula (OR*) 4-aSi(R c) a (E); and (6) the use of (I) as catalyst or co-catalyst in the preparation of (A) by polymerization and/or rearrangement of (B). R ccatalytic function suitable for generating a carbene; R* : alkyl; and a : 1-3.