Process for the production of crosslinked siloxanes by disproportionation
AssigneeGeneral Electric Company
InventorJohn S. Razzano
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Abstract
The present invention relates to a new silicone cure system. More particularly, the present invention discloses that a siloxane system containing sufficiently high levels of T or Q species in addition to M, D and a limited amount of silanol species can be cured by linear phosphonitrilic chloride disproportionation catalyst.
Claims37
A process for producing a highly branched and cured organopolysiloxane ag disproportionation, comprising the steps of
- (a) mixing siloxanes comprising triorganosiloxane units, diorganosiloxane units with siloxanes comprising monoorganosiloxane units and/or SiO.sub.4/2 units;
- and
- (b) adding with agitation a phosphonitrilic disproportionation/condensation catalyst to the mixture of said step (a).
A process for preparing a cross-linked and cured organopolysiloxane, comprising the step of
- (a) mixing siloxanes comprising diorganosiloxane units with siloxanes comprising monoorganosiloxane units, or mixtures thereof, wherein the silanol content of the mixture is between 100 and 3000;
- and
- (b) adding with agitation a disproportionation/condensation catalyst to the mixture of said step (a).
A two part silicone cure system, comprising
- (a) a siloxane mixture comprising
- (i) siloxanes comprising triorganosiloxane units, diorganosiloxane units;
- and
- (ii) a sufficient amount of siloxanes comprising monoorganosiloxane units, SiO.sub.4/2 units, and mixtures thereof;
- and
- (b) a disproportionation/condensation catalyst.
A process for making cross-linked and cured organopolysiloxane, comprising the steps of
- (a) mixing 1.0-5.0% silanol-containing, soluble silicone monoorganosiloxane resin with linear disiloxanol polymer;
- (b) adding a condensation/disproportionation/condensation catalyst.
Dependencies are inferred from the claim text.