GB1395923A - Process for the manufacture of a silver halide photographic emulsion - Google Patents

Abstract

1395923 Preparing silver halide emulsions FUJI PHOTO FILM CO Ltd 31 May 1972 [2 June 1971] 25560/72 Heading G2C A method of preparing a silver halide emulsion for flash exposure comprises adding to the emulsion a rhodium compound before or during precipitation of the silver halide grains and an iridium compound before or during precipitation of the grains and/or during physical ripening of the emulsion. The grains are dispersed in an aqueous emulsion of a hydrophilic colloid which may also contain aqueous ammonia. The rhodium compound may be a simple salt such as di- or tri-halide e.g. chloride or bromide, or an octahedral complex salt such as an alkali metal or ammonium hexaholegenorhodate e.g. potassium hexachlororhodate, ammonium hexachlororhodate. The iridium salt may be a simple salt such as a tri- or tetra-halide e.g. Cl or Br, an octahedral complex acid such as hexahalogenoiridic (III) acid or hexahalogenoiridic (IV) acid or the alkali metal or ammonium salts thereof, e.g. potassium hexachloroiridate (IV). The hydrophilic colloid may be a natural organic colloid such as gelatine or a gelatine derivative e.g. phthalic gelatine, maleic gelatine, carboxymethyl gelatine or trimellitic gelatine or a synthetic organic colloid e.g. polyvinyl alcohol, carboxymethyl cellulose or a co-condensate of maleic anhydride, phthalic acid and a polyol.