Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Patent
1995-03-21
1997-12-02
Letscher, Geraldine
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
430642, 430503, 430531, 430536, 430537, 430539, 430627, 430628, 430567, 430569, G03C 1005, G03C 1494
Patent
active
056934610
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 different types of gelatins used. The heteroflocculated packet emulsions can be further stabilized via hardening of the gelatins surrounding the particles in the packet clusters using a concentrated gelatin hardener. Such packet emulsion clusters are suitable for use in mixed packet color photography.
REFERENCES:
patent: 5026632 (1991-06-01), Bagchi et al.
patent: 5399480 (1995-03-01), Whitson et al.
patent: 5441865 (1995-08-01), Lewis et al.
Bagchi Pranab
Chen Tien-teh
Dannhauser Thomas Joseph
Lewis John Derek
Whitson Mark Anthony
Anderson Andrew J.
Eastman Kodak Company
Letscher Geraldine
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