Patent US3751251A successfully refreshed from Google Patents.
US3751251A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preparing bleach-fix regenerator concentrate
Assignee: Eastman Kodak Co
•
Filing: 1972-03-01
•
Granted: 1973-08-07
•
Expires: 1992-03-01
Abstract
Abstract A method is described for preparing bleach-fix regenerator concentrates which remain free of crystalized precipitate after prolonged storage and which are useful in the regeneration of photographic bleach-fix solutions which employ a ferric salt of an aminopolycarboxylic acid as a bleaching agent and a thiosulfate as a fixing agent. The method comprises the steps of: A. DISSOLVING AN AMINOPOLYCARBOXYLIC ACID AND THIOSULFATE ION IN AN AQUEOUS ALKALINE MEDIUM; AND B. ADDING SUFFICIENT GASEOUS SULFUR DIOXIDE TO THE SOLUTION OF (A) TO LOWER THE PH thereof to between about 5.4 and 6.0.
Inventors
- 👤 J Surash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:45
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/395; G03C5/3952
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
19 words
The method of claim 1 wherein said aqueous medium has a pH of between about 7 and about 9.
Claim 2
Dependent Claim
34 words
The method of claim 2 wherein from about 0.15 to about 0.35 moles of aminopolycarboxylic acid and from about 0.5 to about 0.85 moles of thiosulfate ion are dissolved per 100 ml of water.
Claim 3
Dependent Claim
12 words
The method of claim 3 wherein said aminopolycarboxylic acid is ethylenediaminetetraacetic acid.
Claim 4
Dependent Claim
16 words
The method of claim 3 wherein said aqueous medium comprises an aqueous solution of ammonium hydroxide.
Claim 5
Dependent Claim
19 words
The method of claim 5 wherein said aminopolycarboxylic acid is supplied in the form of the partially neutralized acid.
Claim 6
Dependent Claim
34 words
The method of claim 6 wherein said partially neutralized aminopolycarboxylic acid is made by forming an aqueous slurry of ethylenediaminetetraacetic acid, and adding sufficient base to partially neutralize and hence solubilize the ethylenediaminetetraacetic acid.
Claim 7
Dependent Claim
11 words
The method of claim 7 wherein said base is ammonium hydroxide.
Claim 8
Dependent Claim
38 words
The method of claim 5 wherein said aminopolycarboxylic acid and thiosulfate are added to water and the solution rendered basic by the addition of from about 0.1 to about 0.25 moles of base per 100 ml of water.
Claim 9
Dependent Claim
11 words
The method of claim 9 wherein said base is ammonium hydroxide.
References Cited (Backward Citations)
US2063297A
Cited
US3700450A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |