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US 2014/0155644 A1Published application
Separating cyclic siloxanes from short-chain siloxanes having terminal hydroxyl groups
AssigneeWacker Chemie AG
InventorsAlfred Popp, Christine Kaes, Klaus Kaeppler, Ulrike Buettner
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Abstract
Cyclic siloxanes are separated from short chain hydroxyl-terminated siloxanes by contact with steam at at least 650 hPa absolute. The cyclic siloxanes and other components which are separated by use of steam can be recovered by phase separation, and preferably used in other processes.
Claims9
1-4. (canceled)
A method for removing cyclic siloxanes from a mixture which contains cyclic siloxanes of the formula (I)
- (R1R2SiO)m (I),
- where
- R1 are alkyl groups having 1 to 12 carbon atoms,
- R2 have the meanings of R1, or are aryl groups having 5 to 30 carbon atoms or alkenyl groups having 2 to 12 carbon atoms, and
- m is an integer of from 3 to 20,
- and which contains short-chain siloxanes having terminal hydroxyl groups, comprising separating the cyclic siloxanes using a steam stream at at least 650 hPa absolute, where the remaining fraction of cyclic siloxanes in the mixture, based on the sum of cyclic siloxanes of the formula (I) in which m =4 to 6, is in a range of 0-20,000 ppm by weight.
3 more elements
Dependencies are inferred from the claim text.