Production of silver halide emulsions

US6261758A · kind A · utility

Assignee

• Agfa-Gevaert NV · BE

Inventors

• Ralf Wirowski · Neunburg vorm Wald, DE
• Hans-Ulrich Borst · Elsdorf, DE
• Detlev Kapitza · Leverkusen, DE
• Jorg Siegel · Leverkusen, DE
• Peter Bergthaller · Bensberg, DE
• Heinrich Odenwalder · Leverkusen, DE

Key dates

• Filing date: Jul 14, 2000
• Grant date: Jul 17, 2001
• Expiry date: Jul 14, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G03C2200/33
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

The production of tabular silver bromide-iodide emulsions and silver bromide-chloride-iodide emulsions with an aspect ratio .sup.3 2, an iodide content from 1 to 40 mol % and a chloride content from 0 to 20 mol %, by the process steps of (a) silver halide nucleus precipitation, and (b) at least one further precipitation of silver halide, wherein rein at least one aromatic five- or six-membered, heterocyclic compound, which is free from--SH--,--SSO.sub.2 H-- and--SSO.sub.2 R groups, is added in an amount from 10.sup.-9 to 10.sup.-4 mol/mol silver during nucleus precipitation or during the precipitation of an inner zone of the silver halide grain which is different from the nucleus precipitate, results in an improved speed/grain size ratio and in an increased stability of a photographic material which contains an emulsion produced in this manner.