GB1340789A - Converting metal images to formazan dye images - Google Patents

Abstract

1340789 Converting metal images to formazan dye images EASTMAN KODAK CO 22 April 1971 [23 April 1970] 10801/71 Heading G2C An imagewise distribution of a metal having a standard oxidation potential more positive than -0.98 volt in a hydrophilic colloid binder layer containing a terpolymer having at least 0À1 wt per cent of active methylene groups in aliphatic side chains, is converted to an imagewise distribution of a non-diffusible formazan dye by treating the metal image with either (i) an aqueous solution of a tetrazolium salt containing a metal ion complexing group or (ii) an aqueous solution of a tetrazolium salt not containing a metal ion complexing group, the solution containing a metal ion complexing agent, the aqueous solution in either case having a solution reaction potential as defined in Specification 1333613 of at least 0À01 volt. The active methylene group in the terpolymer may be separated from the main polymer chain by at least 3 carbon atoms. The hydrophilic colloid binder may comprise gelatine and 1 to 85% based on the weight of gelatine, of the terpolymer. The terpolymer may comprise (A) at least 50 wt per cent of repeating units derived from: CH 2 = C(R)-CO-OR 1 wherein R is H or methyl; and R 1 is alkyl; (B) 3 to 30 wt per cent of repeating units derived from acrylic acid (or salts) having the formula: CH 2 = C(R 2 )-CO 2 M or CH 2 = C(R 2 )-CO-OR 3 SO 3 M wherein R 2 is H or alkyl; R 3 is a divalent group having each valency on a different carbon atom and which is a saturated or unsaturated hydrocarbon group or an aliphatic hydrocarbon group in which a chain of carbon atoms extending between the O and S atoms bonded to R 3 is interrupted by an O or S atom; and M is a cation; and (C) 2 to 20 wt per cent of repeating units derived from: CH 2 = C(R 4 )-CO-OR 5 wherein R 4 is H, alkyl or -R 6 -O-CO-CH 2 X wherein R 6 is alkylene; and X is aliphatic acyl or CN; R 5 is alkyl, cycloalkyl, aryl or -R 6 -O-CO-CH 2 X, provided that one and only one of R 4 and R 5 is always -R 6 -O-CO-CH 2 X. The binder may contain e.g. a terpoly (alkyl acrylate-alkali metal salt of 3-sulphopropyl acrylate-aceto-acetoxyethyl methacrylate) or a terpoly (alkyl acrylate-acrylic acid-acetoacetoxyethyl methacrylate) or a combination thereof. The tetrazolium salt may be 2, 3, 5-triphenyl- 2H-tetrazolium chloride.