GB1278744A - Colour developing compositions - Google Patents

Abstract

1278744 Photographic colour developer composition EASTMAN KODAK CO 26 Feb 1970 [27 Feb 1969] 9250/70 Heading G2C A colour photographic developer composition comprises a primary aromatic amine colour developing agent and an antioxidant having the formula R<SP>1</SP>-CH(OH)-CO-R in which R is H, carboxyl, alkyl having 1 or 2 C atoms, or hydroxy alkyl having 1 or 2 C atoms and R<SP>1</SP> is H, carboxyl, hydroxymethyl or formyl, such that when R is carboxyl, R<SP>1</SP> is not a hydroxymethyl group and such that the compound is capable of existing in equilibrium as an enol form and is not capable of intramolecular cyclization. Concentration of the above compound is in the range 0À1-20 g/l and of the developing agent, 0À5-14 g/l. Typical of the above compounds are dihydroxyacetone, glycolaldehyde, glyceraldehyde, and dihydroxymaleic acid. The composition may contain water, an alkali e.g. an alkali metal tetraborate, an alkali metal sulphite, a diffusible dye forming coupler, a silver halide solvent, an antifoggant, a diffusible competing coupler or a thickening agent e.g. a carboxy (lower alkyl) substituted cellulose. Numerous colour developing agents are listed. These colour developing compositions give better photographic speeds and densities than those containing either no antioxidants or known antioxidants. These antioxidants are not silver halide solvents and prevent loss of colour developing agent due to aerial oxidation and also of coupler which would otherwise couple with the aerially oxidized colour developing agent.