Patent US3214405A successfully refreshed from Google Patents.
US3214405A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of polycarbonate resins
Assignee: Airco Inc
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Filing: 1961-07-31
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Granted: 1965-10-26
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Expires: 1981-07-31
Abstract
No abstract record available.
Inventors
- 👤 Bernard F Crowe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:28
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/20; C08G64/30; C08G64/307
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
34 words
A PROCESS OF PREPARING POLYCARBONATE RESINS WHICH COMPRISES REACTING A DIHYDROXY DIPHENYL ALKANE AND DIPHENYL CARBONATE BY ESTER INTERCHANGE REACTION IN THE PRESENCE OF A CATALYST SYSTEM COMPRISING SODIUM DITHIONITE AND 2,6-DITERTIARY BUTYL P-CRESOL.
Claim 2
Dependent Claim
34 words
A PROCESS OF PREPARING POLYCARBONATE RESINS WHICH COMPRISES REACTING A DIHYDROXY DIPHENYL ALKANE AND DIPHENYL CARBONATE BY ESTER INTERCHANGE REACTION IN THE PRESENCE OF A CATALYST SYSTEM COMPRISING SODIUM DITHIONITE AND 2,6-DITERTIARY BUTYL P-CRESOL.
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) | 1968-10-25 | 1969-04-26 | 1969-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-10-25 | 1973-04-26 | 1973-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-10-25 | 1977-04-26 | 1977-10-26 | $7700.00 | Window Closed / Lapsed |