METHOD OF PREPARING BROMOIODOSILVER PHOTOGRAPHIC EMULSION Russian patent published in 1995 - IPC

FIELD: photographic materials. SUBSTANCE: emulsion is prepared by a single-jet emulsification with the successive addition to the solution 1 containing gelatin, KBr, KJ, water and one of the following substance of the formula H(CF₂)₁₀-CH₂OH, O-F₁₃C₉O-C₆H₄-C(O)-NH-C₂H₅OH, CF₃(CFCl)₂-(CF₂)₄-C(O)-NH-CH₂OH taken at concentration (1.2-2.4) x (1,2-2,4)·10^-2 mole/mole AgHal, solution 2 containing AgNO₃ and water and solution 3 containing AgNO₃ and water. Then precipitation and isolation of the solid phase is carried out by sodium polyvinyl sulfate and bringing up of ρ value up to 1.0-1.5, precipitate washing, dispersing, chemical sensitization [chemical maturation is carried out using sodium thiosulfate, potassium thiocyanate and sodium benzenesulfinate taken at concentration (4.7-15.6) x (4,7-15,6)·10^-2 mole/mole AgHal] spectral sensitization with successive addition of three sensitizing agents - 3, 3,3′-di-(β-hydroxyethyl)-5,5-dimethoxy-9-ethylthiacarbocya-nine-p-toluenesulfonate, 3, 3,3′-di-β-hydroxyethyl)-9-methylthiacarbocyanine chloride and 3, 3,1′-diethyl-5-hydroxy-6-methylthia-2-quinocyanine-p-toluene- sulfonate [preferably one of indicated sensitizing agents after addition all three is added at concentration (0.6-1.8) x (0,6-1,8)·10^-2 mole per 1 mole AgHal] After sensitization wetting agent is added, sodium salt of sulfosuccinic acid di-2-ethylhexyltetraethyleneglycolic ester at concentration (2.1-4.2) x (2,1-4,2)·10^-3 mole/mole AgHal. Tanning agent is chrome acetate and fluoroglycine. Under these conditions photoemulsion sensitivity is increased by 2.1-3.1-fold, coefficient of modulation transfer is improved by 40% granularity is increased by 66% resolution capability is increased by 24% at retained for density and metallic silver application on the black and white photofilm. EFFECT: enhanced photosensitivity, improved properties of emulsion. 2 cl, 1 tbl