Patent US3697464A successfully refreshed from Google Patents.
US3697464A
Expired / Lapsed
US
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Preparation of pigmentary beta-quinacridone
Assignee: Wyeth Holdings LLC
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Filing: 1971-03-15
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Granted: 1972-10-10
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Expires: 1991-03-15
Abstract
Abstract THIS INVENTION RELATES TO A PROCESS OF PRODUCING PIGMENTARY LINEAR QUINACRIDONE OF THE "BETA" CRYSTALLINE FORM BY TREATING QUINACRIDONE MATERIAL WITH AN ARYL SULFONIC ACID, OPTIONALLY IN THE PRESENCE OF SULFURIC ACID, DILUTING THE RESULTANT MIXTURE WITH WATER TO CAUSE PRECIPITATION, HEATING THE PRECIPITATED PRODUCT IN THE AQUEOUS MENSTRUM AND RECOVERING THE DESIRED PRODCUT FROM THE MIXTURE.
Inventors
- 👤 Vito Albert Giambalvo
- 👤 Philip Randolph Ruby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:43
CPC Classifications
C; C09; C09B; C09B48/00
Claims Analysis
Total Claims: 0
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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) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |