Method for the preparation of an improved photographic tabular emulsion rich in chloride
US5885763A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1997 |
| Grant date | Mar 23, 1999 |
| Priority date | — |
| Expiry date | Oct 23, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/167
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method is disclosed of preparing of a photographic silver halide emulsion comprising precipitating in one or more precipitation steps in a reaction vessel, followed by desalting by means of flocculation and washing or by means of ultrafiltration, said emulsion comprising gelatin as a binder and {100} tabular silver halide grains containing at least 50 mole % of chloride, wherein at least 40% by number of all grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 2, an average thickness of at most 0.5 .mu.m, and an average equivalent circular crystal diameter of 0.3 .mu.m or more, characterized in that during said precipitation step(s) said gelatin binder present in said reaction vessel is substantially free of calcium ions and is oxidized to a degree in order to have a methionine content of at most 4000 ppm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.