The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 02, 1997
Filed:
Mar. 21, 1995
Pranab Bagchi, Webster, NY (US);
Tienteh Chen, Penfield, NY (US);
Thomas Joseph Dannhauser, Pittsford, NY (US);
John Derek Lewis, Webster, NY (US);
Mark Anthony Whitson, Webster, NY (US);
Eastman Kodak Company, Rochester, NY (US);
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.