GB1277660A - Silver dye-bleach process of colour photography - Google Patents

Abstract

1277660 Bleaching catalysts for the silver dyebleach process FUJI PHOTO FILM CO Ltd 16 July 1969 [16 July 1968] 35904/69 Heading G2C A method of preparing a colour photographic image by a silver dye-bleach process comprises dye-bleaching a colour photographic light-sensitive element in the presence of a phenazine-N-oxide, as a bleaching catalyst, represented by the general formula: - wherein R, which may be the same or different, represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group, a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, a nitro group, a cyano group, a carboxy group, a sulpho group, an acylamino group, a sulphonamino group, a halogen atom or a carbocyclic aromatic residue formed by the condensation of two R groups bonded to two adjacent carbon atoms. The said phenazine-N-oxide may be present in the silver halide gelatino emulsion layer or a gelatino subsidiary layer of the colour photographic lightsensitive element, in the proportion 0À01 to 2% by weight based on the weight of the gelatin in said photographic layer. The said phenazine-N-oxide may be in the dye-bleaching bath in the proportion 0À0005 to 0À100 g. per litre of the dye-bleaching bath. The said compound may be present in a processing bath prior to the dye-bleaching processing, which processing bath may be a developer, fixing, stopping or hardening bath or a bath for containing the phenazine -N-oxide. Many examples of the phenazine -N-oxides are given.