GB1309779A - Super-sensitized silver halide photographic emulsions - Google Patents

Abstract

1309779 Supersensitized silver halide photographic emulsion FUJI PHOTO FILM CO Ltd 13 July 1970 [14 July 1969] 33924/70 Heading G2C [Also in Division C3] A photographic silver halide emulsion contains at least one sensitizing dye of the formula:- wherein R, R 1 , R 2 and R 3 each represents an alkyl, substituted alkyl, allyl or an alkyl group; L represents a monomethine group or aliphatic chain which may together with the N atom in the heterocyclic nucleus containing Z, complete a heterocyclic ring, R 1 being absent when L forms a heterocyclic ring with the N atom shown; R 4 is H, or an alkyl or aryl group; m, n, and p each represents 1 or 2, and d represents 0, 1 or 2; X<SP>#</SP> reoresents an anion , an intramolecular salt being formed when p is 1; Z and Z 1 each represent the non-metallic atoms needed to complete a heterocyclic nucleus; in supersensitizing combination with at least one condensate of formaldehyde with a hydroxybenzene or derivative thereof of one of the formulae:- wherein R 5 and R 6 individually represent -OH, -OM, -OR 7 , -NH 2 , -NHR 7 , -N(R 7 ) 2 , -NHNH 2 or -NHNHR 7 wherein R 7 is 1-8C alkyl or aryl or aralkyl; M is an alkali or alkaline earth metal; X 1 is OH or halogen; X 2 is halogen; and n<SP>1</SP>, n<SP>2</SP>, n<SP>3</SP> and n<SP>4</SP> individually represent 1, 2 or 3, the case where n<SP>3</SP>=n<SP>4</SP>=3 being excluded. The heterocyclic nucleus completed by Z or Z 1 may be a thiazole, benzothlazole, naphthathiazole, oxazole, benzoxazole, naphthoxazole, selenazole, benzoselenazole, naphthoselenazole, thiazoline, 2-quinoline, 4- quinoline, benzimidazole, 3, 3'-dialkylindolenine, 2-pyridine or 4-pyridine nucleus. The substituted alkyl group may be a hydroxy-, acetoxy-, sulphato-, carboxy- or sulpho-alkyl group. Many examples of dyes and condensates are given. In some cases the presence of the condensate results in a reduction in fog.