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

FIELD: production of movie and photographic materials. SUBSTANCE: photoemulsion is prepared by two-jet emulsification at pBr 0.9-1.45 and 40-60 C with addition of equimolar quantities of aqueous solutions of AgNO₃, KBr and KJ (content is 0.5-1.5 mol.) to the aqueous-gelatinous solution at constant and equal volume rates [2-5]·10^-7 mol/cm³·s for 60-120 min, and then aqueous solution of AgNO₃ is added additionally up to pBr 22± 0,10.1. Then the second emulsification is carried out at 40-60 C with addition of 2N aqueous solution of AgNO₃ to emulsion at volume rate [2-5]·10^-7 mol/cm·s and 0.3-1N aqueous solution of KJ at volume rate [0,7-3,5]·10^-8 mol/cm³·s up to pBr value 3-0.1. After emulsification termination acetic acid is added up to pH 5.1-0.1 following by isolation of solid phase with sulfopolystyrene, washing, dispersing, chemical sensibilization using C-salt, Na₂S₂O₃, AuCNS, KCNS, sta-salt and spectral sensibilization with dye - 3-ethyl -5- [1′-methyldihydro 1′ 2′ pyridylidene-2]thiazolidinethiene-2-one-4 at concentration (450-720)·10^-6 mole/mole Ag. Safety period of emulsion photoproperties is increased up to 60 days without decrease of photosensitivity. EFFECT: enhanced quality of photoproperties at photoemulsion storage. 3 tbl