Method of preparing light-sensitive silver halide emulsions and dispersions of photographically useful compounds
US5627019A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1995 |
| Grant date | May 6, 1997 |
| Priority date | — |
| Expiry date | Aug 31, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C7/388
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method is provided of preparing a light-sensitive silver halide emulsion or a dispersion of a photographically useful compound comprising the steps of precipitating silver halide or photographically useful compound in the presence of colloidal silica serving as a protective colloid, coagulation washing the precipitate formed and redispersing the silver halide or the photographically useful compound, characterised in that the coagulation takes place in the presence of hydroxy ethyl cellulose as, e.g., hydroxy ethyl cellulose, hydroxy propyl cellulose, methyl cellulose etc., as a polymer capable of forming hydrogen bridges with the silica, in an amount sufficient to form coagulable aggregates with the silica particles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.