US3738963A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of polycarbonates
Assignee: Akzo NV
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Filing: 1971-09-14
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Granted: 1973-06-12
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Expires: 1991-09-14
Abstract
Abstract A PROCESS FOR THE PRODUCTION OF POLYARBONATES WHEREIN A DI- OR POLYVALENT ALCOHOL WHICH IS AT LEAST PARTYL ESTERIFIED WITH TRICHLOROACETIC ACID IS HEATED IN THE PRESENCE OF A BASIC COMPOUND AT ABOUT 60*C. TO 200*C., CHLOROFORM BEING SPLIT OFF AND REMOVED FROM THE REACTION. THE RESULTING POLYCARBONATES ARE ESPECIALLY USEFUL, E.G. AS FOAMED PRODUCTS.
Inventors
- 👤 H Praetorius
- 👤 A Vogts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:12
CPC Classifications
C; C07; C07C; C07C69/00; C07C69/62; C07C69/63; C08; C08G; C08G64/00; C08G64/02; C08G64/16; C08G64/20; C08G64/38; C07C2601/00; C07C2601/12; C07C2601/14
Claims Analysis
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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) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |