Patent US3890283A successfully refreshed from Google Patents.
US3890283A
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Process for post-polymerizing polyglycolic acid
Assignee: Wyeth Holdings LLC
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Filing: 1973-06-04
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Granted: 1975-06-17
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Expires: 1993-06-04
Abstract
Abstract A process for producing ultra high molecular weight polyglycolic acid comprising subjecting polyglycolic acid of conventional molecular weight to a prolonged heat treatment under vacuum.
Inventors
- 👤 Donald James Casey
- 👤 Martin Epstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:11
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/02; C08G63/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
50 words
A PROCESS FOR INCREASING THE MOLECULAR WEIGHT OF POLYGLYCOLIC ACID COMPRISING HEATING SAID POLYGLYCOLIC ACIDS IN A SOLID STATE AT A TEMPERATURE BETWEEN ABOUT 150*C. AND 220*C. FOR A PERIOD OF TIME OF AT LEAST 4 DAYS AT AN ABSOLUTE PRESSURE BETWEEN ABOUT 0.1 MM. AND 1.0 MM. OF MERCURY.
Claim 2
Dependent Claim
50 words
A PROCESS FOR INCREASING THE MOLECULAR WEIGHT OF POLYGLYCOLIC ACID COMPRISING HEATING SAID POLYGLYCOLIC ACIDS IN A SOLID STATE AT A TEMPERATURE BETWEEN ABOUT 150*C. AND 220*C. FOR A PERIOD OF TIME OF AT LEAST 4 DAYS AT AN ABSOLUTE PRESSURE BETWEEN ABOUT 0.1 MM. AND 1.0 MM. OF MERCURY.
Claim 3
Dependent Claim
15 words
A process according to claim 1 in which the polyglycolic acid is in pellet form.
Claim 4
Dependent Claim
17 words
The process according to claim 1 in which the temperature is maintained at about 190* to 200*C.
Claim 5
Dependent Claim
15 words
The process according to claim 3 in which the polyglycolic acid is in pellet form.
Claim 6
Dependent Claim
48 words
The process according to claim 1 in which the polyglycolic acid being heated contains as a molecular weight regulator a reactive content or chemically combined content of from about 0.05 to about 1.5 mole percent of an alcohol devoid of any reactive groups other than alcoholic hydroxy groups.
References Cited (Backward Citations)
US3422181A
Cited
US3390134A
Cited
US3621003A
Cited
US3626948A
Cited
US3772420A
Cited
US3718621A
Cited
US3634359A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |