Patent ID: 6753134
Filing Date: 2004-06-22
Classification: G03C

Abstract:
A process for the preparation of a radiation-sensitive silver halide emulsion comprised of high bromide cubical silver halide grains, the process comprising:(a) providing in a stirred reaction vessel a dispersing medium and high bromide silver halide seed grains, the seed grains comprising at least 5 mole % of the final emulsion silver, and (b) precipitating a silver halide shell which comprises at least 5 mole % of the final emulsion silver onto the seed grains to form high bromide cubical silver halide grains by introducing at least a silver salt solution into the dispersing medium at a rate such that the normalized shell molar addition rate, Rs, is above 1.0Ã—10âˆ’2, Rs satisfying the formula: Rs=MsMt&it;ts2where Msis the number of moles of silver halides added to the reaction vessel during the formation of the shell, ts is the run time, in minutes, of the silver salt solution for the formation of the shell, and Mt is total moles of silver halide in the reaction vessel at the end of the precipitation of the shell;wherein the concentration of silver halide grains in the reaction vessel at the end of the precipitation of the shell is at least 0.5 mole/L.