SILVER HALIDE EMULSION AND ITS PRODUCTION AND SILVER HALIDE PHOTOSENSITIVE MATERIAL USING SAID SILVER HALIDE EMULSION

摘要

PURPOSE:To improve the reciprocity law failure characteristic of high sensitivity and low illuminance and to improve a fogging characteristic with lapse of time by incorporating silver halide particles contg. silver iodide whose spherical particles are grown as seed particles and are subjected to halogen substn. at the specific point of time into the titled material. CONSTITUTION:The emulsion contg. the silver halide twin particles having >=5:1 average aspect ratio is obtd. by growing the multiple twin particles and/or the spherical particles obtd. from the multiple twins as the seed particles and subjecting the same to the halogen substn. by iodide corresponding to 0.005-20mol%, more preferably 0.01-10mol% at an optional point of the time between the time when 5-95mol% of the entire particles is formed. The seed emulsion contg. the multiple twin particles has further preferably >=50wt% ratio of the multiple twins with regard to the total seed particles contained in the emulsion. The seed emulsion contg. the spherical particles is obtd. by maturing the emulsion contg. the multiple twin particles in the presence of the silver halide emulsion. The emulsion is more particularly preferably obtd. by maturing the same for 30sec-5min under the conditions of 35-45 deg.C, 0.4-110mol/liter ammonia and 0.03-0.5mol/liter potassium bromide.