METHOD OF PREPARING SILVER HALIDE EMULSION Russian patent published in 1997 - IPC

FIELD: photographic emulsions. SUBSTANCE: invention relates to emulsions applicable when fabricating black-and-white and colored negative materials. Purpose of invention is to increase light sensitivity and reduce optical density of fog with retaining resolution capability and granularity. Emulsion with 5-13.5 mol % of silver iodide is prepared through fractional single-jet emulsification by way of introducing, under stirring, solution 2 including silver nitrate and water in two portion into solution 1 including potassium bromide, potassium iodide, gelatin, 2-hydroxypropyl(trioxyethyl)-4-isooctylphenol, sodium benzenesulfinate, and water followed by deposition of solid phase, dispersing at ρ = 0.8-1.6, adjusting pAg to 9.0-9.5, pH to 5.7-6.3, chemical sensibilizing in presence of sodium thiosulfate, potassium thiocyanate, sodium benzenesulfinate, and gold thiocyanate. Once chemical sensitizing completed, spectral sensitizer 3-ethyl-5- (1'-methyldihydro[1', 2"]-2'-pyrilidene)-2-thiazolidinethion-4-on, or potassium salt of sulfoethyl-5-(1'-methyldihydro-[1',2']-2'- pyrilidene)-2-thiazolidinethion-4-on, or pyridinium salt - 3,3'-di- g-sulfopropyl-9-ethyl-4,5-4,5'-dibenzothiacarbocyaninebetaine is additionally introduced in quantity (1-4)10^-4 mol per 1 mol silver halide, and, before sprinkling, fine-grain silver bromide-iodide, or chloride-iodide, or bromide emulsion with average size of silver halide microcrystals d_av = 0.05-0.10 mcm with ρ 0.7-1.6, and pAg 8.8-9.2 is added with proportion of coarse to fine-grain emulsions being from 94: 6 to 67:33. Once spectral sensitizer is additionally introduced, yellow color forming component - 2-chloro-5-g-(2,4-di- tert-amylphenoxy)butyroylaminoanilide-a-N- benzylhydantoylpivaloylacetic acid in amount 510^-2-1 10^-4 mol per 1 mol AgHal is added. EFFECT: increased light sensitivity and reduced fog. 2 cl, 2 tbl