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US 4,286,055 AGranted
Process for the preparation of monodisperse photographic silver halide emulsions of improved sensitivity
AssigneeE. I. Du Pont de Nemours and Company
InventorsRalf-Udo P. Forster, Rolf H. F. Metzger
Life of this patent
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Abstract
The speed of monodisperse photographic emulsions made by balanced doubled jet precipitation and converted into a AgBr and/or AgBrI emulsion is increased by ripening in the presence of sulfur compounds at a pH between 8 and 9.5.
Claims6
A process for the preparation of a mondisperse silver halide emulsion of improved sensitivity, by the steps of
- (a) precipitating a monodisperse silver chloride or silver chloride-bromide emulsion,
- (b) converting this emulsion to a silver bromide or silver bromide-iodide emulsion by mixing it with a conversion solution of a bromide or a bromide-iodide mixture at elevated temperature, and
- (c) chemically ripening the converted emulsion,
- characterized in that the chemical ripening is carried out in the presence of a sulfur sensitizer at a pH value between 8 and 9.5.
1 more element
Dependencies are inferred from the claim text.