Patent GB-568323-A (GB)
Title: Improvements in colour photography
IPC: G03C7/26
Filed: 1943-05-11
Abstract: 568,323. Colour photography. COOTE, J. H., and AUSTIN, A. ST. J. May 11, 1943, No. 7476. [Class 98 (ii)] A multi-colour photographic image is produced by producing in a single silver halide emulsion layer, coated with an organic hydrophilic colloid, a predetermined colour image or images, sensitizing the colloid coating with a substance or substances adapted after printing and processing, to provide the colour image necessary to complete the multi-colour image, the substance or substances being other than a cyanotype sensitizer used to sensitize a coating on an emulsion layer containing a yellow image of an insoluble metal salt mordanted with a basic yellow dye and a magenta image of a nickel dialkylglyoxime, printing and processing the corresponding colour image without substantially altering the form and density of the already formed colour image or images and the normal individual colour characteristics thereof. The colloid layer preferably contains the same colloid, e.g. gelatin, regenerated cellulose, polyvinyl alcohol, or water-permeable resins, as that used in the emulsion layer, and mav be sensitized with a water-soluble alkali or ammonium bichromate, a water-soluble leuco base of a dye (e.g. of the triphenylmethane series), with a light-sensitive diazonium compound, or with a silver halide produced in situ by double decomposition between a watersoluble silver salt and a cadmium, ammonium, or potassium halide. Loading agents, e.g. glycerol, erythritol, mannitol, or sodium sulphate, may be added to the sensitizing solution to prevent penetration into the emulsion layer. The image produced in the emulsion layer may be either a blue-toned image (e.g. Prussian Blue) or an orange-red-toned image (e.g. a uranium-toned image). Two differently coloured images may be produced in the emulsion layer, e.g. a magenta nickel dimethylglyoxime image and a yellow-dyed silver iodide image produced as in Specification 553,377. In example 1, an orange-red component negative is printed into the emulsion layer and irontoned blue-green, the supercoated colloid layer is then sensitized with aqueous ammonium bichromate solution, and an image printed therein from a blue-green component negative, and the chromium oxide image produced is used as a mordant for 1 : 2 : 6- or 1 : 2 : 7-trihydroxyanthraquinone applied in aqueous solution to give an orange-red image. In example 2, the chromium oxide image is coloured by applying an aqueous solution containing Quinoline Yellow and Natural Carmine. In example 3, an image is printed from the blue-green component negative into the emulsion and is uranium-toned and an image is printed from the orange-red component negative into the bichromated colloid layer and the chromium oxide image produced used as a mordant for Diamine Blue. In example 4, the orange-red image is produced as in example 3 and the colloid layer is sensitized with an aqueous solution of the leuco base of Malachite or Brilliant Green containing nitroglycerine or nitromannitol. An image is printed thereon from an orange-red component negative and is fixed with chloracetic acid solution, and the residual leuco dye is washed out. In example 5, two component images are produced in the emulsion and the colloid layer is sensitized with sodium or potassium toluene diazo sulphonate. An image may be printed from the green component negative and a magenta image produced by coupling with phenol or #-naphthol, or an image may be printed from the red-component negative and a blue image produced by treatment with a mixture of p-phenylenediamine, alpha-naphthol, and caustic soda. In example 6, yellow silver iodide and magenta nickel dimethylglyoxime images are produced in the emulsion layer as in Specification 553,377 and silver halide is produced in the colloid layer by first impregnating with aqueous ammonium, potassium, or cadmium chloride, bromide, or iodide and then with aqueous silver nitrate acidified with nitric acid, and an image is printed therein from the red component negative and is iron-toned blue-green after development. The Provisional Specification refers also to the use as the coupling component when the diazosulphonate is used as the light sensitizing agent of m-phenylenediamine.