PURPOSE: To obtain a negative type photographic silver halide emulsion with high surface sensitivity and low internal sensitivity by a double jet method by keeping an excess concn. of water soluble silver salt and an acidic pH until the amount of added silver reaches a specified percentage of the total amount of silver to be added.
CONSTITUTION: An emulsion is prepared while keeping 10-5W10-2mol/l concn. of silver ion (5W2pAg) and 1W4pH and increasing the adding speed of water soluble silver salt and that of water soluble halide continuously or in steps in accordance with the growth of silver halide particles until the amount of added silver reaches at least 1/15 of the total amount of silver to be added. Thus, a single-dispersion emulsion in which ≥80wt% of the silver halide particles have a diameter within ±40% of the average diameter is obtd. By sensitizing the emulsion by reduction or with sulfur or gold, a negative type photographic silver halide emulsion having a narrow particle size distribution and a uniform crystal habit is stably obtd. in a short time.
YAMAGUCHI TAKASHI
SHIOZAWA HIROAKI
KOITABASHI HIROO
MATSUZAKA MASASHI
| JPS5849938A | 1983-03-24 |