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US4895967A
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Method for making cyclic poly(siloxane)s
Assignee: General Electric Co
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Filing: 1988-09-26
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Granted: 1990-01-23
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Expires: 2008-09-26
Abstract
Abstract A method is provided for making cyclic poly(siloxane) by incrementally contacting linear polysilxoane with a fixed bed cracking catalyst, such as an acidic Zeolite under reduced pressure. The resulting volatile cyclic poly(siloxane) is then recovered.
Inventors
- 👤 James V. Crivello
- 👤 Julia L. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:01
CPC Classifications
C; C08; C08G; C08G77/00; C08G77/04; C08G77/38; C08G77/045; C08G77/06; C08G77/10; C08G77/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
92 words
A method for making cyclic poly(siloxane) which comprises, (1) incrementally contacting substantially linear poly(organosiloxane) to a fixed catalyst bed at a temperature in the range of 200° C. to 800° C. and a pressure of from 760 to 0.01 torr in an oxygen-free atmosphere to produce volatile cyclic poly(siloxane), and (2) condensing and thereafter recovering the volatile cyclic poly(siloxane) from (1), where the substantially linear poly(organosiloxane) consists essentially of from 3 to 20, chemically combined organosiloxy units selected from the class consisting of diorganosiloxy units, organohydrogen siloxy units and a mixture thereof.
Claim 2
Independent Claim
92 words
A method for making cyclic poly(siloxane) which comprises, (1) incrementally contacting substantially linear poly(organosiloxane) to a fixed catalyst bed at a temperature in the range of 200° C. to 800° C. and a pressure of from 760 to 0.01 torr in an oxygen-free atmosphere to produce volatile cyclic poly(siloxane), and (2) condensing and thereafter recovering the volatile cyclic poly(siloxane) from (1), where the substantially linear poly(organosiloxane) consists essentially of from 3 to 20, chemically combined organosiloxy units selected from the class consisting of diorganosiloxy units, organohydrogen siloxy units and a mixture thereof.
Claim 3
Dependent Claim
22 words
A method for making cyclic poly(siloxane) in accordance with claim 1, where the linear poly(organosiloxane) consists essentially of chemically combined diorganosiloxy units.
Claim 4
Dependent Claim
14 words
A method in accordance with claim 2, where the substantially linear poly(organosiloxane) is poly(dimethylsiloxane).
Claim 5
Independent Claim
19 words
A method in accordance with claim , where the substantially linear poly(organosiloxane) consists essentially of chemically combined organohydrogensiloxy units.
Claim 6
Dependent Claim
15 words
A method in accordance with claim 4, where the linear poly(organosiloxane) is a methylhydrogen polysiloxane.
Claim 7
Dependent Claim
17 words
A method in accordance with claim 1, where the fixed catalyst bed is an acidic Zeolite bed.
Claim 8
Dependent Claim
21 words
A method in accordance with claim 1, where the fixed catalyst bed is a molecular sieve modified by a mineral acid.
Claim 9
Dependent Claim
20 words
A method in accordance with claim 1, where the linear poly(organosiloxane) is a copolymer of diorganosiloxy units and organohydrogensiloxy units.
Claim 10
Dependent Claim
20 words
A method in accordance with claim 8, where the copolymer consists essentially of chemically combined dimethylsiloxy units and methylhydrogensiloxy units.
Claim 11
Dependent Claim
17 words
A method in accordance with claim 1, where the pressure is from 0.1 torr to 40 torr.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-22 | 1993-07-24 | 1994-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-22 | 1997-07-24 | 1998-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-22 | 2001-07-24 | 2002-01-23 | $7700.00 | Window Closed / Lapsed |