Procédé de photographie en couleur

1,173,017. Silver dye bleach process and material. EASTMAN KODAK CO. Dec. 12, 1966 [Dec.10, 1965], No.55637/66. Heading G2C. In the silver dye bleach process an exposed and developed photographic material having a support carrying a silver halide emulsion layer having in association therewith a dye or dye precursor which precursor is rendered incapable of forming dye in exposed areas in the bleaching step and which emulsion contains a sufficient quantity of the salt of an acid which, when converted to the free acid, lowers the pH of the layer to a level at which the dye is bleached or precursor inactivated in the presence of a silver halide solvent in exposed areas, is contacted with a processing web comprising a polymer with free acid substituents e.g. phenol sulphonic acid formaldehyde condensation polymer acrylic acid and polystyrene sulphonic acid or a ballasted sulphonic or phosphonic acid e.g. dodecane sulphonic acid, hexadecane phosphonic acid and α-sulpho stearic acid, which sets free the aforementioned free acid from its salt so that the dye is bleached or precursor inactivated in exposed areas. Specified salts are ammonium, alkali metal and alkaline earth metal halides, nitrates, sulphates, sulphonates, trichloroacetates, phosphates and phosphonates which may be present in the developer, an alkaline activator solution for developer incorporated materials or an emulsion. The photographic material may be in the form of an integral 3-part material comprising an emulsion layer, the web and a pressure rupturable pod containing alkaline activator. The web may be coated with a water-permeable timing layer e.g. polyvinyl alcohol, gelatine and polyvinyl alcohol polyvinyl acetate mixtures. The bleachable dye may also constitute the developer. The silver halide complexing agent may be present in the activator solution, developer solution or the processing web and is, for example, di or trimethylolurea or 1, 3-bis or 1-(#-hydroxyethyl) imidazolidine-2-thione. Silver bleaching agents e.g. o and m-nitrobenzene sulphonic acids and silver dye bleach catalysts may be present in the emulsion, alkaline processing material or the acidic web. A specified incorporated developer is 3, 6-bis(2-hydroxyethyl)-2, 3, 4, 5, 6, 7-hexahydro- 1, 8-dioxo-3-diazophenanthrene.