US3720654A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Molecular sizing process for preparing low molecular isobutylene-conjugated polyene copolymers
Assignee: Covestro International SA
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Filing: 1971-05-21
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Granted: 1973-03-13
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Expires: 1991-05-21
Abstract
Abstract LOW MOLECUAR WEIGHT BUTYL-TYPE COPOLYMERS HAVING NARROW MOLECULAR WEIGHT DISTRIBUTIONS ARE PREPARED BY CONTACTING A HIGHER MOLECULAR WEIGHT BUTYL-TYPE COPOLYMER, E.G., A BUTYL RUBBER, WITH A CATALYST COMPOSITION COMPRISING A TRANSITION METAL SALT, AN ORGANOMETALLIC COMPOUND OF A METAL OF GROUP I-A, II-A, II-B, OR III-A OF THE PERIODIC TABLE, A PROTON DONOR, AND HYDROGEN. THE CATALYST COMPOSITION PREFERABLY COMPRISES A HALIDE OF TUNGSTEN, MOLYBDENUM, OR RHENIUM, AN ALKYL ALUMINUM HALIDE, A LOWER ALKANOL, AND HYDROGEN.
Inventors
- 👤 J Olechowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:12
CPC Classifications
C; C08; C08F; C08F8/00; C08F8/50
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-12 | 1976-09-11 | 1977-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-12 | 1980-09-11 | 1981-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-12 | 1984-09-11 | 1985-03-13 | $7700.00 | Window Closed / Lapsed |