US3928042A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preservatives for photographic developers
Assignee: TDK Micronas GmbH
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Filing: 1974-07-22
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Granted: 1975-12-23
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Expires: 1994-07-22
Abstract
Abstract The storage life of silver halide developer solutions is extended by the addition to the solutions of salts, esters and amides of plicatic acid.
Inventors
- 👤 Arthur Karchmar
- 👤 Jr Leo Lawrence Nejelski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:06
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/29; G03C5/305
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
55 words
AN AQUEOUS SOLUTION FOR DEVELOPING PHOTOGRAPHIC MATERIAL COMPRISING A SILVER HALIDE DEVELOPING AGENT AND AS A PRESERVATIVE THEREFOR A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SALTS, ESTERS AND AMIDES OF PLICATIC ACID IN AN AMOUNT EFFECTIVE TO EXTEND THE STORAGE LIFE OF SAID SOLUTION, SAID AMOUNT BEING AT LEAST 0.01% ON A WEIGHT/VOLUME BASIS.
Claim 2
Dependent Claim
55 words
AN AQUEOUS SOLUTION FOR DEVELOPING PHOTOGRAPHIC MATERIAL COMPRISING A SILVER HALIDE DEVELOPING AGENT AND AS A PRESERVATIVE THEREFOR A COMPOUND SELECTED FROM THE GROUP CONSISTING OF SALTS, ESTERS AND AMIDES OF PLICATIC ACID IN AN AMOUNT EFFECTIVE TO EXTEND THE STORAGE LIFE OF SAID SOLUTION, SAID AMOUNT BEING AT LEAST 0.01% ON A WEIGHT/VOLUME BASIS.
Claim 3
Dependent Claim
27 words
The solution of claim 1 in which the plicatic acid compound is neutralized to a pH of at least 7 prior to its addition to the solution.
Claim 4
Dependent Claim
14 words
The solution of claim 2 in which the plicatic acid compound is a salt.
Claim 5
Dependent Claim
12 words
The solution of claim 3 in which the salt is potassium plicatate.
Claim 6
Dependent Claim
14 words
The solution of claim 2 in which the plicatic acid compound is an ester.
Claim 7
Dependent Claim
12 words
The solution of claim 5 in which the ester is n-propyl plicatate.
Claim 8
Dependent Claim
14 words
The solution of claim 2 in which the plicatic acid compound is an amide.
Claim 9
Dependent Claim
12 words
The solution of claim 7 in which the amide is n-propyl plicatamide.
Claim 10
Dependent Claim
21 words
The solution of claim 2 in which the amount of plicatic acid compound is from 0.1 to 5 grams per liter.
Claim 11
Dependent Claim
63 words
A process for extending the storage life of aqueous solutions for developing photographic materials comprising adding to said solution containing a silver halide developing agent a preservative compound selected from the group consisting of salts, esters and amides of plicatic acid in an amount effective to extend the storage life of said solution, said amount being at least 0.01% on a weight/volume basis.
Claim 12
Dependent Claim
63 words
A process for extending the storage life of aqueous solutions for developing photographic materials comprising adding to said solution containing a silver halide developing agent a preservative compound selected from the group consisting of salts, esters and amides of plicatic acid in an amount effective to extend the storage life of said solution, said amount being at least 0.01% on a weight/volume basis.
Claim 13
Dependent Claim
29 words
The process of claim 10 in which the preservative compound is added as an aqueous solution of said plicatic acid compound neutralized to a pH of at least 7.
Claim 14
Dependent Claim
12 words
The process of claim 11 in which the preservative is potassium plicatate.
Claim 15
Dependent Claim
14 words
The process of claim 11 in which the aqueous solution is a stock solution.
Claim 16
Dependent Claim
13 words
The process of claim 11 in which the photographic material is photographic negative.
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) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |