Photographic silver halide emulsions - comprise silver halide particles of specified min. silver chloride content and shape

摘要

Photographic Ag halide emulsions comprise Ag halide particles with a AgCl content of at least 60 mol.% and an octatetracontaedral crystal form comprising 48 three-cornered surfaces of which each convex contacts two of its neighbouring surfaces for formation of a peak and each concave contacts one of its neighbouring surfaces for formation of a peak. Emulsions pref. contain a methine dye at 4 x 10 power(-6) - 8 x 10 power(-3) mol/mol Ag halide. Emulsions pref. also contain a thiocyanate pref. present at 10 power(-5) to 10 power(-1) mol/mol Ag halide. Prodn. of the emulsion comprises formation of Ag halide particles with AgCl content of at least 60 mol.% in the presence of a polymer as synthetic peptisator contg. repeating units of an ethylenically unsatd. monomer with thioether bonds in a mole fraction of around 20-100 mol.% USE/ADVANTAGE - Photographic material exhibits rapid processing, reduced fogging, enhanced colour-sensitivity and high sensitivity.