Double-jet precipitation processes and products thereof
AssigneeEastman Kodak Company
InventorJong-Shinn Wey
Life of this patent
Estimating the term…
Abstract
A double-jet precipitation process is disclosed for preparing radiation-sensitive photo- graphic emulsions containing tabular silver chloride grains which are substantially internally free of bromide and iodide. In forming the emulsions chloride and silver salt solutions are concurrently run into a dispersing medium while controlling both pH and pAg. Tabular grains having an average aspect ratio of greater than 8:1 are obtained.
Claims17
A radiation-sensitive photographic emulsion comprising a dispersing medium and silver chloride grains, wherein at least 50 percent of the total projected area of said silver chloride grains is provided by tabular grains which are substantially internally free of both bromide and iodide, have an average aspect ratio greater than 8:1, and have opposed, substantially parallel major {111} crystal faces.
In a double-jet precipitation process of preparing a radiation-sensitive photographic emulsion comprised of a dispersing medium and silver halide grains which are substantially internally free of iodide and bromide by concurrently introducing chloride and silver salt solutions into the dispersing medium in the presence of ammonia,
- the improvement comprising, while introducing the chloride salt solution,
- maintaining the pAg within the dispersing medium in the range of from 6.5 to 10 and
- maintaining the pH within the dispersing medium in the range of from 8 to 10,
- thereby precipitating at least 50 percent, based on total grain projected area, of the silver chloride grains in the form of tabular grains having an average aspect ratio greater than 8:1 and having opposed, substantially parallel major {111} crystal faces of triangular or truncated triangular configuration.
Dependencies are inferred from the claim text.