| 摘要 |
<p>Silver halide photographic emulsions with associated colour couplers for use in colour photography, are sensitised with a 1,2,4-dithiazolidino-3-thione or dimethylene-trisulphide sulphur sensitiser of formula (I) or (II) or a mixt. (R is H, aliphatic gp. or (non)aromatic cyclic nucleus and R' is H, aliphatic gp. or (non)aromatic nucleus, at least one of R and R' being other than H. Pref. R and R' are both 1-4C alky, esp. methyl gps. or R and R' (same or different) are 1-4C alkyl or phenyl gps.). The (I) or (II) are added to the silver halide emulsion prior to chemical digestion and subsequent addn. of a colour coupler, prior to coating the resulting compsn. 8 Specific cpds. (I)/(II) are disclosed, including 4-methyl-5-methylimino- 1,2,4-dithiazolidine-3-thione. Addn. of the (I)/(II) in the ripening process for silver halide emulsions give good sensitisation whilst restraining the development of fog centres. Process gives good increase in sensitivity without necessity for using excessive amts. of antifoggants, as in prior art emulsions.</p> |
