METHOD OF MANUFACTURING SILVER BROMIDE/IODIDE PHOTOGRAPHIC EMULSION CONTAINING T CRYSTALS Russian patent published in 1997 - IPC

FIELD: photographic industry. SUBSTANCE: silver bromide/iodide photographic emulsion containing T crystals is manufactured using two-jet emulsifying performed in two steps, in the first of which, silver nitrate aqueous solution and potassium or ammonium iodide aqueous solution are added to water-gelatin solution and, in the second step, emulsion obtained is supplemented with silver nitrate aqueous solution and potassium or ammonium bromide aqueous solution followed by Ostwald recrystallization in presence of ammonia, solid phase precipitation by sulfopolystyrene, washing, dispersing, and chemical sensitizing by sodium thiosulfate and gold-hydrochloric acid. According to invention, the two emulsifying steps are carried out with constant rate of introduction of solutions (45-50 ml/min), at 2-2.5 M concentration of silver nitrate, potassium or ammonium iodide and bromide, and temperature 45-50 C, whereas after each emulsifying step, solid phase is precipitated by sulfopolystyrene, washed, and dispersed in water-gelatin solution. EFFECT: improved procedure. 1 tbl