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US 5,298,384 AGranted
Pressure fog-resistant photographic element
AssigneeEastman Kodak Company
InventorsKenneth J. Lushington, Sucheta Tandon
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AssigneeEastman Kodak Company
InventorsKenneth J. Lushington, Sucheta Tandon
Estimating the term…
A method for controlling pressure-induced fog in a silver bromide photographic material involves surface treatment of the emulsion AgBr grains with thiocyanate and an iodide salt. In particular, a process for making a pressure fog-resistant photographic emulsion includes steps of forming a photographic emulsion containing cubic or cubooctahedral silver bromide grains, surface-treating the AgBr grains with a thiocyanate by adding the thiocyanate to the emulsion, chemically sensitizing the emulsion, maintaining the emulsion at a temperature and for a time sufficient to allow the thiocyanate to react with the grain surfaces, and then surface-treating the AgBr grains with an iodide salt by adding the salt to the emulsion in an amount and under conditions effective to fill in cubic faces of the AgBr grains. The latter step partially or fully converts the AgBr grains to octahedral grains. A photographic element can then be made by coating the emulsion on a suitable base.
A photosensitive element, comprising a support and a colloid-silver halide photographic emulsion coated on said support, said emulsion containing octahedral or cubooctahedral grains, the interior of said grains consisting essentially of AgBr and the exposed exterior surface thereof consisting essentially of AgBrI, the AgBrI being deposited mainly on cubic faces of an underlying cubic or cubooctahedral AgBr gain so as to improve the pressure fog resistance of the photosensitive element.
A photosensitive element, comprising a photographic film support and a colloid-silver halide photographic emulsion coated on said support, said emulsion containing octahedral or cubooctahedral grains consisting essentially of 0.2 to 2 mole % I and 98 to 99.8 mole % Br per mole Ag and having an edge size of at least about 0.5 micron, the interior of said grains consisting essentially of AgBr and the exposed exterior surface thereof consisting essentially of AgBrI, the AgBrI being deposited mainly on cubic faces of an underlying cubic or cubooctahedral AgBr grain so as to improve the pressure fog resistance of the photosensitive element, and wherein said cubic faces of said underlying AgBr grains have been surface treated with a thiocyanate prior to forming AgBrI thereon in an amount effective to improve the pressure desensitization resistance of the photographic element.
Dependencies are inferred from the claim text.