Patent US5421339A successfully refreshed from Google Patents.
US3689462A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing polycarbonates
Assignee: PPG Industries Inc
•
Filing: 1971-05-19
•
Granted: 1972-09-05
•
Expires: 1991-05-19
Abstract
Abstract POLYCARBONATES PREPARED FROM AN ALKYLENE OR DIALKL CARBONATE (OR 1,2-EPOXIDE WITH CARBON DIOXIDE) AND MONOMERIC POLYOLS ARE PREPARED IN GOOD YIELD AT ATMOSPHERIC PRESSURE AND/OR WITH HIGH CARBON DIOXIDE CONCENTRATIONS IN SHORT REACTION TIMES BY EMPLOYING A STANNATE CATALYST OF THE FORMULA: MXSNO3 WHERIN M IS AN ALKALI METAL, ALKALINE EARTH METAL OR AMMONIUM, PREFERABLY POTASSIUM OR SODIUM; AND X IS AN INTEGER OF 1 OR 2 SUFFICIENT TO SATISFY THE VALENCE REQUIREMENTS.
Inventors
- 👤 Michael J Maximovich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:20
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/02; C08G64/0291; C08G64/0208; C08G64/20; C08G64/30; C08G64/32; C08G64/34
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
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) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |