PROCESS OF PRODUCTION OF HALOGEN-AND-SILVER PHOTOGRAPHIC EMULSION WITH MICROCRYSTALS Russian patent published in 1998 - IPC

FIELD: photographic chemistry, preparation of bromine-iodine or bromine-chlorine-iodine-silver photographic emulsion with microcrystals, processes of production of black-and-white, X-ray, color photographic materials of various assignment. SUBSTANCE: process involves preparation of suspension of nucleus microcrystals by single-jet or double-jet injection of alkaline metal or ammonium into solution No.1 containing hydrophilic colloid, ammonium base in the amount of 0.05-0.5 mole/l and water and solution No.2 containing silver nitrite and water with pJ=0.5-3.0 , growth of produced microcrystals by double-jet injection of solution No.2 and solution No.3 containing bromine or mixture of bromine and chloride of alkaline metal or ammonium and water into prepared suspension with constant value of рВг=1.5-3.5, injection of ammonium base in the amount of 0.1-1.5 mole/l into reaction medium and aging under constant value of рВг. Solution No.3 may contain up to 55.0 molecular per cent of chloride of alkaline metal of ammonium. At stage of preparation of nucleus microcrystals there is used 1.0-15.0 per cent by weight of silver nitrite of their total amount. Stage of growth of microcrystals can be conducted in presence of 1•10^-3-1•10^-5 mole/mole of total amount of silver nitrite of nitrogen- carrying heterocyclic composition of formula 1, where R¹,R²,R³ are same or H is different, C₁-C₈ alkyl, or formula 2, where X=S, NH, O, Y=N, C-R⁴, R⁴=H, SH,C₁-C₅ alkyl, or formula 3, where R⁵=H, SH, C₁-C₅ alkyl or formula 4, where Q=N-R⁶, S, O, R⁶=H, C₁-C₅ alkyl, phenyl, n=1 or 2. With n=1 z=H, with n=2 z is absent. Proposed technology makes it possible to prepare assortment of poly ((C_v> 25%)>25.0%) or monodispersive (d_av>25.0%) halogen-silver photographic emulsions with microcrystals having μ=0.5-3.0 and aspect of ratio d_av:h_av=2:1-25:1 with specified granulometric characteristics depending on assignment of emulsion. Process duration amounts to 20- 60 min, time spent for limiting stage of growth of microcrystals including large microcrystals equal in size is not more than 20-30 min as compared with 90 min needed for preparation of large microcrystals of same size by prototype process. EFFECT: enhanced efficiency of process. 5 cl, 3 tbl