MANUFACTURE OF PLANAR PARTICLE EMULSION HAVING LOW DISPERSION DEGREE

• Main Authors: AREN KEE CHIYAN TSUAUA, MAMII KAMUUNGU
• Format: Patent
• Language: English
• Published: 13.07.1993
• Subjects: AUXILIARY PROCESSES IN PHOTOGRAPHY; CINEMATOGRAPHY; ELECTROGRAPHY; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; HOLOGRAPHY; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR,STEREO-PHOTOGRAPHIC PROCESSES; PHOTOGRAPHY; PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHYSICS; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ARTCOLLECTIONS [XRACs] AND DIGESTS

PURPOSE: To provide a method for producing a photographic emulsion contg. plate-like silver halide particles exhibiting low total particle dispersion. CONSTITUTION: A group of the silver halide particle cores having a parallel twin plane is formed, and then a part of the cores are aged. Subsequently, the remaining cores having a parallel twin plane are grown to form a plate-like silver halide particle. The total dispersion of this emulsion is lowered by incorporating bromine ion into a dispersion medium before the cores are formed and further incorporating a polyalkylene oxide block copolymer surfactant contg. at least two end oleophilic alkylene oxide block units connected by the hydrophilic alkylene oxide block units occupying at least 4% of the mol.wt. of the copolymer at a concn. where the particle dispersion is decreased when a parallel twin plane is formed in the core.