The present invention relates to a method of manufacturing silver halide emulsion, particularly to a method of manufacturing a silver halide emulsion low in fog, excellent in graininess, low in aging fog, and excellent in aging stability.
In the area of silver halide photographic light-sensitive materials, various approaches are being made in pursuit of a much higher speed. As one of such approaches, there is proposed to use core/shell type silver halide grains different in chemical components or physical properties between the inner portion and the other portion, generally, silver halide grains different in silver halide composition (hereinafter referred to as a core/shell type emulsion). In using such core/shell type emulsions for the purpose of enhancing the sensitivity, it is proposed to make up the light-sensitive layer into a multilayered structure in which the upper layer (a layer on the light-irradiated side) is a high speed layer.
In general, core/shell type emulsion grains have a structure in which the inner silver halide composition of the grains differs from the silver halide composition of the other portion of the grains; and, present inventors have found the fact that a core/shell type emulsion comprising grains of this structure having a high iodide content phase (a portion in which the iodide content is higher than that in the other portion) gives a fog high than that comprising grains having no high iodide content phase. Such an increased fog causes a large deterioration in graininess and a substantial desensitization with respect to a sensitivity-fog ratio.
Particularly, use of a core/shell type emulsion in a multilayered light-sensitive material involves risks to increase fog or aging fog and impair the shelf-life.