PROCESS OF PREPARATION OF BROMINE-IODINE-SILVER PHOTOGRAPHIC EMULSION Russian patent published in 1995 - IPC

FIELD: manufacture of photomaterials. SUBSTANCE: two-jet emulsification is conducted with injection into solution 1 containing gelatine, KBr, NH₃ with pBr 1.5-3 and pH 7.4-10.0(they are kept constant to full outflow of entire volume of solution) and water of solution 2 containing AgNO₃ and water and solution 3 containing KBr taken in amount of 0.6-0.95 mole/mole of silver in solution 2, of iodine potassium in amount of 0.05-0.4 mole/mole of silver in solution 2. Then growing of shell is performed by two-jet injection of solution 4 containing AgNO₃ and water and solution 5 containing KBr, iodine potassium in amount of 0.01-0.05 mole/mole of silver in solution 4 and water. After completion of emulsification nitric acid is injected to pH 4-4.5 and aqueous solution AgNO₃ to pH 4.0-2.0 with subsequent injection of KBr to pAg 8.0-9.5. Then solid phase is precipitated, washed, dispersed, chemical sensitization with use of sodium benzolesulphinate, sodium thiosulphate, potassium radanide and ammonium diradonoaurate is conducted. In this case light sensitivity of emulsion (S_0,85) grows from 90 to 130. EFFECT: increased light sensitivity. 2 cl, 2 tbl