PHOTOSENSITIVE EMULSION WITH SILVER CHLORIDE-RICH {100} FLAT PLATY GRAIN

摘要

PROBLEM TO BE SOLVED: To obtain a photosensitive emulsion with silver chloride-rich flat platy photosensitive silver halide grains by introducing a specified polyoxyalkylene block copolymer into a reactor after a 1st growth step. SOLUTION: At least three separate precipitation steps are carried out in an aq. medium in a reactor and desalting is carried out by washing after flocculation or by ultrafiltration. The separate precipitation steps are one nucleus forming step and subsequent 1st and 2nd growth steps. A polyoxyalkylene block copolymer of the formula is introduced into the reactor after the 1st growth step. The block copolymer contains at least three terminal hydrophilic polyoxyethylene groups and at most one terminal hydrophobic polyoxypropylene block unit besides ethylenediamine units as tetravalent bonding units.