Process For Preparing SiC-Bonded Polyethersiloxanes
AssigneeEvonik Degussa GmbH
InventorsWilfried Knott, Dagmar Windbiel
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Abstract
A process for preparing SiC-bonded polyethersiloxanes by precious metal-catalysed addition of olefinically unsaturated polyethers onto siloxanes having SiH groups is described, wherein, prior to commencement of reaction, the siloxane having SiH groups is mixed with an olefinically unsaturated polyether and with a polyethersiloxane by stirring, and then contacted with a precious metal catalyst and optionally further additives, and the SiC bond formation reaction is conducted up to an SiH conversion, determined by gas-volumetric means, of at least 97%.
Claims12
A process for preparing SiC-bonded polyethersiloxanes by precious metal-catalysed addition of olefinically unsaturated polyethers onto siloxanes having SiH groups, characterized in that
- (i) prior to commencement of reaction, the siloxane having SiH groups is mixed together with a polyethersiloxane, preferably by stirring, and then
- (ii) in a second step, this preliminary mixture is contacted with an olefinically unsaturated polyether and with a precious metal catalyst and optionally further additives, preferably with further stirring,
- and the SiC bond formation reaction is conducted up to an SiH conversion, determined by gas-volumetric means, of at least 97%.
Dependencies are inferred from the claim text.