Polymerization of siloxanes

US6284859A · kind A · utility

Assignee

• Dow Corning Corporation · US

Inventors

• Peter Cheshire Hupfield · Düsseldorf, DE
• Avril Surgenor · Cardiff, GB
• Richard Taylor · Cincinnati, US

Key dates

• Filing date: Dec 9, 1999
• Grant date: Sep 4, 2001
• Expiry date: Dec 9, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G77/08
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A polymerization process comprising mixing siloxanes having silicon-bonded groups R' with ionic phosphazene base catalysts and allowing condensation via reaction of Si--R' groups with the formation of a Si--O--Si linkage, R' denoting a hydroxyl group or a hydrocarbonoxy group having up to 8 carbon atoms is claimed. The catalysts may be of the general formulae: EQU {((R.sup.1.sub.2 N).sub.3 P.dbd.N--).sub.x (R.sup.1.sub.2 N).sub.3-x P--N(H)R.sup.2 }.sup.+ {A.sup.- } or EQU {((R.sup.1.sub.2 N).sub.3 P.dbd.N--).sub.y (R.sup.1.sub.2 N).sub.4-y P}.sup.+ {A}.sup.- in which R.sup.1 is hydrogen or an optionally substituted hydrocarbon group or in which two R.sup.1 groups bonded to the same N atom may be linked to complete a heterocyclic ring, R.sup.2 is hydrogen or an optionally substituted hydrocarbon group, x is 1, 2 or 3, y is 1, 2, 3 or 4 and A is an anion. Also claimed is a process which comprises mixing siloxanes having silicon-bonded groups R' and cyclic or linear siloxanes having no silicon-bonded groups R' with ionic phosphazene base catalysts and allowing the siloxane having silicon-bonded groups R' to condense and the cyclic and linear siloxanes having no silicon-bonded R' group…