US3713826A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sulfite esters as preservatives for black and white developing agents
Assignee: HUNT P CHEM CORP
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Filing: 1970-11-16
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Granted: 1973-01-30
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Expires: 1990-11-16
Abstract
Abstract A METHOD OF AND SOLUTION FOR BLACK AND WHITE DEVELOPING OF SILVER HALIDE GELATIN LAYERS WITH THE USE OF A BATH THAT INCLUDES A CONVENTIONAL BLACK AND WHITE DEVELOPING AGENT OR AGENTS AND OTHER CONVENTIONAL CONSTITUENTS SUCH AS RESTRAINERS, ANTI-FOGGANTS, SEQUESTRANTS, SILVER HALIDE SOLVENTS AND GELATIN HARDENERS AND WHICH FOR THE PRESERVATIVE USES A SULFITE ESTER SELECTED FROM THE CLASS CONSISTING OF 1,2ETHYLENESULFITE; 1-METHYL-1,2-ETHYLENESULFITE; 1,2-DIMETHYL1,2-ETHYLENESULFITE; 1,3-PROPYLENESULFITE AND DIMETHYLSULFITE IN THE PRESENCE OF AN ALKALI IN AN AMOUNT SUFFICIENT TO PROVIDE FOR THE BATH A PH OF AT LEAST 8.
Inventors
- 👤 D Sykes
- 👤 H Kroll
- 👤 T Finch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:05
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/29; G03C5/305
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |