GB1442470A - Processing of silver halide photographic materials - Google Patents

Abstract

1442470 Bleaching photographic materials FUJI PHOTO FILM CO Ltd 5 July 1974 [7 July 1973] 30025/74 Heading G2C A developed, imagewise exposed silver halide photographic material is bleached with a bleaching solution containing (a) as the bleaching agent a complex formed from a polyvalent ferric iron, cobalt, nickel or cupric copper cation and an organic phosphonic acid and (b) a re-halogenating agent and treating the bleached material with a fixing solution. Suitably an amino-poly(methylene phosphonic acid, e.g. of the Formula R<SP>1</SP>N (CH 2 PO 3 M 2 ) 2 where M represents a hydrogen atom or a cation that imparts water-solubility; and R<SP>1</SP> represents an alkyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, an alicyclic group or a heterocyclic group, is used. Alternatively, the phosphonic acid may be of the Formula R<SP>2</SP>R<SP>3</SP>C (PO 3 M 2 ) 2 where R<SP>2</SP> represents a hydrogen atom or an alkyl, aralkyl, alicyclic or heterocyclic group and R<SP>3</SP> represents a hydrogen atom, a hydroxyl group, an alkyl, an alkyl group or - PO 3 M where M is a hydrogen atom or a cation which imparts water-solubility or R<SP>2</SP> is an alkyl group substituted with a hydroxyl group, an alkoxy group, a halogen atom, -PO 3 M 2 , -CH 2 PO 3 M 2 or -N (CH 2 PO 3 M 2 ) 2 wherein M is an alkali metal or other cation which imparts watersolubility. Alkali metal and ammonium halides are specified rehalogenating agents. The bleaching solution may also contain a pH buffer, a nitrate, sulphite, mercapto compound, stain-inhibiting agent, polyamine, alkylamine, polyethylene oxide, or nitrogen-containing heterocyclic compound. The photographic material suitably comprises a silver halide emulsion layer containing a colourforming coupler.