GB1333613A - - Google Patents

Abstract

1333613 Forming dye images from metal images EASTMAN KODAK CO 19 April 1971 [25 Feb 1970] 22118/71 Heading G2C An imagewise distribution of a metal having a standard oxidation potential more positive than - 0À98 volts is converted to animagewise distribution of a formazan dye by treating the metal image in the presence of a water soluble diffusible tetrazoluim salt with an aqueous solution of a diffusible metal complexing agent which forms a complex with silver ions having a smaller cumulative equilibrium constant # 2 (defined as the concentration of silver ion complex divided by the concentration of silver ion which latter concentration is multiplied by the concentration of complexing agent squared) than the complex of silver ions with cyanide ions; the solution reaction potential E (which is the sum of two half cell reactions E oxidation + E reduction) of the aqueous solution being at least +0À01 volt. The tetrazoluim salt is preferably present in aqueous solution, and preferably has one of the formulae:- wherein R<SP>1</SP> and R<SP>3</SP> represent a substituted or unsubstituted aryl or heterocyclic group; R<SP>2</SP> represents a substituted or unsubstituted aryl or heterocyclic group, H, alkyl mercaptoalkyl, OH, carboxyester, amino which may be substituted, carbamoyl which may be substituted by methyl, ethyl or phenyl groups, sulphamoyl, sulphonamido, carbonamido, NO 2 or a carboxy or sulpho group or a salt thereof; X is a anion; D is an arylene or arylenealkylenearylene group; and E is an alkylene, arylene or arylenealkylene group. The formazon dye formed may be diffusible or non-diffusible. The metal may be silver, nickel, copper, aluminium, iron, palladium, zinc, lead or tin. The complexing agent may be a water-soluble thiosulphate, thiourea, ethylenethiourea, thiocyanate, sulphurcontaining dibasic acid or a diol containing sulphur atoms, many examples of which are given.