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

FIELD: production of photographic materials. SUBSTANCE: photographic emulsion is prepared by emulsification, physical ageing, precipitation of solid phase, washing, dispersing and chemical sensitizing. The latter process is carried out in the presence of Na₂S₂O₃ and AuCNS at pH 6.3-7.1 and pBr 2.8-3.1. Alcohol H(CF₂)₆CH₂OH or salt H(CF₂CF₂)_nCOONa (their quantities being (4-5)·10^-4 M/M Ag or (5-10)·10^-5 M/M Ag are added into said emulsion in 5-30 min before said chemical sensitizing starts. The process is followed by spectral sensitizing which is carried out with the help of following agents: 3, 3,3′-di-(β-oxyethyl)-5, 5,5′-dimethoxy-9-ethylthiocarbocyanine-p-toluene sulfonate, its quantity being (5,0-7,2)·10^-5 M/M Ag; 3, 3,3′-di-(β-oxyethyl)-9-methyl thiocarbocyanine chloride, its quantity being (9-10)·10^-5 M/M Ag; 3, 3,1′-diethyl-5-oxy-6′-methylthia-2′-quinocyanine-p-toluene sulfonate, its quantity being (6,8-8,75)·10^-5 M/M Ag. Method enables to increase sensibility of photographic materials in visual region of spectra by 30-100% EFFECT: increases sensibility of photographic materials in visual region of spectra. 2 tbl