Photographic bleaching composition and processing method using ternary iron carboxylate complexes as bleaching agents
US5582958A · kind A · utility
6Cited by
10References
24Claims
0Family size
Assignee
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Key dates
| Filing date | Jan 10, 1995 |
| Grant date | Dec 10, 1996 |
| Priority date | — |
| Expiry date | Jan 10, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/131
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A photographic bleaching or bleach/fixing composition contains a water-soluble ternary complex of an iron ion, a polycarboxylate ligand, and a second ligand which has at least one carboxyl group on an aromatic nitrogen heterocycle, such as a pyridinecarboxylic acid. Preferred materials are biodegradable, but all of the ternary complexes can be used in a variety of bleach or bleach/fix processes to good advantage as bleaching agents. They are particularly suitable for use in rehalogenating ferric chelate bleaches.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.