US4439592A
Expired / Lapsed
US
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Preparation of polydiorganosiloxanes having terminal triorganosilyl groups
Assignee: Momentive Performance Materials GmbH
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Filing: 1982-09-13
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Granted: 1984-03-27
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Expires: 2002-09-13
Abstract
Abstract The present invention relates to a process for the preparation of trioganosilyl-terminated polydiorganosiloxanes by basic polymerization of cyclic diorganopolysiloxanes and triorganosilyl-terminated siloxanes, wherein, before the polymerization, a part of the cyclic diorganosiloxane is distilled off in the presence of the polymerization catalyst at a temperature which is at least 10° C. below the polymerization temperature.
Inventors
- 👤 Gunther Maass
- 👤 Hans J. Lucking
- 👤 Karl Brandle
- 👤 Hans-Heinrich Moretto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:21
CPC Classifications
C; C08; C08G; C08G77/00; C08G77/04; C08G77/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
68 words
In the preparation of a triorganosilyl-terminated polydiorganosiloxane by the polymerization at elevated temperature of a cyclic diorganopolysiloxane with a triorganosilyl-terminated siloxane chain length regulator in the presence of a basic catalyst, the improvement which comprises, before polymerization, distilling off a part of the cyclic diorganosiloxane in the presence of the polymerization catalyst at a temperature which is at least 10° C. below the temperature at which polymerization commences.
Claim 2
Dependent Claim
68 words
In the preparation of a triorganosilyl-terminated polydiorganosiloxane by the polymerization at elevated temperature of a cyclic diorganopolysiloxane with a triorganosilyl-terminated siloxane chain length regulator in the presence of a basic catalyst, the improvement which comprises, before polymerization, distilling off a part of the cyclic diorganosiloxane in the presence of the polymerization catalyst at a temperature which is at least 10° C. below the temperature at which polymerization commences.
Claim 3
Dependent Claim
16 words
A process according to claim 1, wherein the distillation is effected while stirring under reduced pressure.
Claim 4
Dependent Claim
20 words
A process according to claim 1, wherein the cyclic diorganosiloxane is heated up together with the catalyst under reduced pressure.
Claim 5
Dependent Claim
23 words
A process according to claim 1, wherein the diorganosiloxane is stirred with the catalyst for at least half an hour before the distillation.
Claim 6
Dependent Claim
21 words
A process according to claim 1, wherein octamethylcyclotetrasiloxane is employed as the diorganosiloxane and potassium hydroxide is employed as the catalyst.
Claim 7
Dependent Claim
56 words
A process according to claim 5, wherein about 5 to 15% of the octamethylcyclotetrasiloxane is distilled off under reduced pressure at a temperature below about 120° C. and in the pressure of about 5 to 20 ppm of basic catalyst based on the material being polymerized, the distillate being recycled for use in a subsequent polymerization.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |