GB1515137A - Supersensitization of silver halide photographic emulsion - Google Patents

Abstract

1515137 Supersensitization FUJI PHOTO FILM CO Ltd 26 Nov 1975 [26 Nov 1974] 48691/75 Heading G2C A silver halide photographic emulsion is spectrally sensitized by adding to it in supersensitizing amounts (1) a trimethine cyanine dye of the general Formula: wherein Z<SP>1</SP> and Z<SP>2</SP> each represents the atoms necessary to complete a thiazoline, pyrroline, oxazole, thiazole, selenazole, imidazole, tetrazole, benzoxazole, naphthoxazole, benzthiazole, naphthothiazole, benzoselenazole, naphthoselenazole, benzimidazole or haphthaoimidazole nucleus, each of which can bear substituents, in which Z<SP>1</SP> and Z<SP>2</SP> are not both a benzoxazole nucleus; R<SP>1</SP> and R<SP>2</SP> each represents an aliphatic group containing 1 to 8 carbon atoms or an aromatic group which is optionally substituted, R‹ represents a hydrogen atom, an alkyl group containing up to 4 carbon atoms, hydroxyalkyl, carboxyalkyl, cyano, aralkyl or phenyl, m, n and p are each 0 or 1 and x represents an inorganic or organic acid anion which forms a salt together with the dye moiety, wherein when the dye moiety forms an internal salt p is 0 and in other cases p is 1, and (2) a heterocyclic compound comprising a heterocyclic ring selected from a pyrazole, pyrimidine, 1,2,4-or 1,2,3-triazole, 1,3,4-, 1,2,4 or 1,2,5- thiadiazole, pyridazine, 1,2,3-, 1,2,4-or 1,3,5- triazine, triazolotriazole, diazaindene, triazaindene and pentazindene ring, which ring bears at least one mercapto group and optionally other substituents, the compound not containing any acidic group and forming upon reaction with silver ion a silver salt which is less soluble in water than silver chloride. The mercapto group can form part of a @ =N-N=C(SH)-, =N-N-C(SH)- or -N-C(SH)-N= group. The heterocyclic rings can contain oxygen, sulphur and selenium atoms in addition to nitrogen. The mercapto compounds are free of any acidic groups other than -SH.