Patent GB-571344-A (GB)
Title: Improvements in colour photography
IPC: G03C7/30
Filed: 1943-07-08
Abstract: 571,344. Colour photography. KODAK, Ltd. (Eastman Kodak Co., and Vittum, P. W.). July 8, 1943, No. 11105. [Class 98 (ii)] Superimposed photographic records in different colours are produced on a single support by colour developing simultaneously a more accessible silver salt emulsion layer thereon not containing a colour coupler with a less accessible silver salt emulsion layer thereon containing a colour coupler in a developing solution which contains dissolved colour coupler (preferably not itself a developing agent) ; the dissolved colour coupler forming a dye image in the emulsion not containing coupler but no appreciable dye image in the emulsion containing colour coupler. The diffusion properties of the dissolved coupler may be such that it only diffuses through the emulsion not containing a coupler without diffusing through the less accessible emulsion containing a coupler in the time required to develop the dye image in the emulsion containing the coupler. Alternatively, the dissolved coupler may have a low reaction rate. The material may have inseparably coated on a single support a less accessible silver salt emulsion layer containing fine discrete particles of a solution of a colour coupler in a solvent therefor, and a more accessible silver salt emulsion not containing colour coupler. The material may have on a single support three silver halide emulsions respectively sensitive to three of the four spectral ranges blue, green, red, and infra-red, one of the emulsions being an uppermost layer inseparably coated over the other two emulsions, this layer being free from colour coupler, and the other two emulsions each containing a dispersion of fine discrete particles containing couplers. In example 1, a support is successively coated with a red-sensitive silver bromide emulsion containing fine discrete particles of a water-insoluble water-permeable binder or oil-former containing a blue-green coupler, a green-sensitive silver bromide emulsion layer containing similar particles containing a magenta coupler, a yellow filter layer, and a blue-sensitive emulsion free from coupler. After exposure, the material is developed in a colour developer containing as yellow coupler p-benzeneazoacetoacetanilide or p - (# - benzoylacetamino) - benzenesulphon - ptert.-amylaniline or p-(p<1>-tert.-amylbenzenesulphonamido) - # - benzoylacetanilide. In example 2, material as in example 1 is developed in a developer containing a coupler with a low reaction rate, e.g. ethyl acetoacetate. A dispersion of a dye solvent, e.g. N-n-amylphthalimide, N-n-amylsuccinimide, n-butyl phthalate, methyl phthalate, veratrole, methyl p - toluenesulphonate, ethylphthalylethylglycollate, or tri-cresyl phosphate, may be added to the sensitive material, preferably only in the coupler-free emulsion. Mixtures of two or more such solvents may be used, or a cellulose derivative or natural or synthetic resin may be added. A dispersion formed by adding a mixture of n-butyl phthalate and ethyl acetate to an aqueous solution of sodium laurylsulphate may be added to the top emulsion. The process may be applied to reversal processing. Specifications 524,154, 524,554, 524,555, 540,368 and 541,589 are referred to.