Mixed packet color photographic system
US5693461A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 1995 |
| Grant date | Dec 2, 1997 |
| Priority date | — |
| Expiry date | Mar 21, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C7/388
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
This invention describes the composition and method of preparation of heteroflocculated packet emulsion clusters containing a light sensitive and selectively photosensitized silver halide emulsion particles and particles of photographic agents such as dye-forming coupler particles. The silver halide emulsion particles are associated with a layer of adsorbed peptizing gelatin with an isoelectric pH of P.sub.1 and the grafted gelatin of the gelatin-grafted-polymer particles comprising the photographic agent has an isoelectric pH of P.sub.2 such that P.sub.1 is different than P.sub.2. At least one of the peptizing and grafted gelatins is an isoing gelatin which is sufficiently derivatized to remove ionic groups thereof such that approaching the isoelectric pH in an aqueous solution of the isoing gelatin causes massive heteroflocculation. Formation of packet emulsion clusters is achieved by heteroflocculation between oppositely charged silver halide particles and gelatin-grafted-latex polymer particles comprising the photographic agents by shift of the pH to within 0.5 pH units of the isoelectric pH of the isoing gelatin and at a value between the two isoelectric pH values of two diffe…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.