METHOD OF PREPARING BROMINE-IODINE-SILVER PHOTOGRAPHIC EMULSION Russian patent published in 1995 - IPC

FIELD: photographic materials. SUBSTANCE: method involves two-jet emulsification, precipitation of the solid phase, washing, dispersing, chemical maturation and spectral sensibilization. Emulsification is carried out at 50-55 C. Before chemical sensibilization stage isobutylphenolthiosulfoacid sodium salt is added additionally at concentration (2.5-5.0) x 10^-4 M/M AgHal. At the stage of spectral sensibilization before sensibilizing agents addition the compound - diphthaloylpolyethyleneglycol ester is added additionally at concentration (50-120)·10^-6 M/M AgHal and dye - 3,3'-diethylthiazolinocarbocyanine-p-toluenesulfonate or 3,3'-di-γ-sulfopropylthiazolinocarbocyanine betaine triethylammonium salt at concentration (60-100)·10^-6 M/M AgHal were added. Then the following compounds were added to the emulsion successively: 3,3′-di-γ -sulfopropyl -9-ethyl-5,5′-dimethoxythiacarbocyanine betaine pyridine salt at concentration (90-165)·10^-6 М/М AgHal, 3,3′-di-γ-sulfopropyl-9-aminothiacarbocyanine betaine ammonium salt at concentration (180-270)·10^-6 M/М AgHal ammonium salt and 3,3'-di-γ-sulfopropyl-9-methylthiacarbocyanine betaine pyridine salt at concentration (250-350)·10^-6 М/М AgHal, or 3,3′-di -γ-sulfopropyl -9-aminothiacarbocyanine betaine ammonium salt at concentration (180-270)·10^-6 AgHal, and 1,1'-diethyl-2,2-quinocyanine salt and 3,3′-di-γ- sulfopropyl-9-ethyl- 6,6′-dimethylcarbocyanine betaine salt at concentration (190-300)·10^-6 М/М AgHal or 3,3'-di-γ- sulfopropyl-9-aminothiacarbocyanine betaine ammonium salt at concentration (180-270)·10^-6М/М AgHal and 1,1′-diethyl- 2,2′-quinocyanine salt and 3,3′-di -γ- sulfopropyl-9-ethyl-5,5'-dimethoxythiacarbocyanine betaine salt at concentration (200-300)·10^-6 М/М AgHal. After every sensibilizing agent an activator of spectral sensibilization-3,3′-[1″,2″-bis(ethoxy)ethyl] bis-(1-ethylbenzimidazolium) is added at concentration 1M per 1M sensibilizing agent. Photosensitivity by criterion A_Do+0,1 is increased up to 40-46 U, resolution capability R 240-260 min/mm, FPM 0.82-0.07. EFFECT: enhanced photosensitivity, improved structural properties. 1 tbl