Patent US2787632A successfully refreshed from Google Patents.
US2787632A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polycarbonates
Assignee: Columbia Southern Chemical Corp
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Filing: 1954-07-07
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Granted: 1957-04-02
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Expires: 1974-07-07
Abstract
No abstract record available.
Inventors
- 👤 Henry C Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:18
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/02; C08G64/0208
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
110 words
A METHOD OF PREPARING A LINEAR POLYCARBONATE HAVING TERMINAL HYDROXYL GROUPS AND AN AVERAGE MOLECULAR WEIGHT BETWEEN 800 AND 5000 WHICH COMPRISES ESTABLISHING A REACTION MEDIUM CONTAINING A SELECTED MOLE RATIO OF AN ALIPHATIC DIESTER OF CARBONIC ACID AND A SATURATED, ACYLIC DIOL, THE DIOL BEING PRESENT IN SLIGHT MOLE EXCESS, HEATING THE MEDIUM UP TO AS HIGH AS ABOUT 200* C. WHEREBY TO EFFECT ESTER-INTERCHANGE AND EVOLVE ALOCHOL, REMOVING THE EVOLVED ALCOHOL FROM THE REACTION MEDIUM DURING THE COURSE OF THE REACTION AND MAINTAINING THE MOLE RATIO OF DIESTER TO THE DIOL PRESENT IN THE REACTION MEDIUM ESSENTIALLY CONSTANT THROUGHOUT AT LEAST A MAJOR PORTION OF THE ESTER-INTERCHANGE PERIOD.
Claim 2
Independent Claim
110 words
A METHOD OF PREPARING A LINEAR POLYCARBONATE HAVING TERMINAL HYDROXYL GROUPS AND AN AVERAGE MOLECULAR WEIGHT BETWEEN 800 AND 5000 WHICH COMPRISES ESTABLISHING A REACTION MEDIUM CONTAINING A SELECTED MOLE RATIO OF AN ALIPHATIC DIESTER OF CARBONIC ACID AND A SATURATED, ACYLIC DIOL, THE DIOL BEING PRESENT IN SLIGHT MOLE EXCESS, HEATING THE MEDIUM UP TO AS HIGH AS ABOUT 200* C. WHEREBY TO EFFECT ESTER-INTERCHANGE AND EVOLVE ALOCHOL, REMOVING THE EVOLVED ALCOHOL FROM THE REACTION MEDIUM DURING THE COURSE OF THE REACTION AND MAINTAINING THE MOLE RATIO OF DIESTER TO THE DIOL PRESENT IN THE REACTION MEDIUM ESSENTIALLY CONSTANT THROUGHOUT AT LEAST A MAJOR PORTION OF THE ESTER-INTERCHANGE PERIOD.
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) | 1960-04-01 | 1960-10-01 | 1961-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-04-01 | 1964-10-01 | 1965-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-04-01 | 1968-10-01 | 1969-04-02 | $7700.00 | Window Closed / Lapsed |