Patent GB-503824-A (GB)
Title: Process of colour photography
IPC: G03C7/30
Filed: 1937-07-07
Abstract: 503,824. Colour photography. KODAK, Ltd. July 7, 1937, No. 7953/39. Convention date, July 7, 1936. Divided out of 503,752. [Class 98 (ii)] A method of producing coloured photographic records on multi -layer material of which at least one of the emulsions contains an insoluble coupling component, consists in subjecting such emulsion containing' a developable silver salt image to photographic colour development with an alkaline coupling developer, removing the coupled product and converting the residual coupling component into a coloured image. An element containing insoluble coupling components in three silver halide emulsion layers is exposed and the latent images are developed with a p-aminodimethylaniline or o-dichlor-paminophenol developer to give insoluble indamines or indophenols. These dyes are chen destroyed by acids or converted into addition products by treatment with alkali sulphate, bisulphate orthiosulphate or with arylsulphinic acids. If the p-aminodialkylaniline has strongly basic substituent groups such as dimethylamino, guanido, biguanido or quaternary ammonium groups, the dyes can be washed out by acids. The procedure for the final dye may be as many of the following proceeds : (a) After exposure or pre-treatment with a fogging agent, the residual components are coupled by development with p-amino-dimethyl-aniline or other coupling developers in 1 per cent aqueous solution rendered alkaline. If the first formed dye has not been removed, it is now washed out with sodium carbonate or caustic alkali. Diazonium compounds may be allowed to react on the reduction products to give increased solubility in sodium carbonate of the first formed dye. (b) Diazonium compounds are allowed to react on the residual component chosen to give required colours. This method is preferably applied to films coated on both sides to allow different diazo compounds to react on the respective sides. The top layer on either side may however be coloured by any known means. An alternative method is to add a coloured coupling component to one or more of the emulsions e.g. azo- or triphenylmethane- or anthraquinone dyes, which react with the diazonium solution. The coupling of the final lemon-yellow dye in the upper layer is prevented by making the latter a derivative of phenol or naphthol having a halogenation in the o or p position to the hydroxyl group thus preventing diazo coupling. A stable and insoluble diazo body, or an insoluble salt of antidiazotate or a diazonium compound, or a diazo-anhydride or an insoluble sulphonate or carboxylate of the last named, may bg added to the emulsions in addition to the coupling component. When treated with acid, these compounds form diazonium salts which couple with the coupling components. (c) If the insoluble coupling components are amines, they may be developed in the first instance, with the 4-sulphonic, 4-carboxylic or 4-thiosulphonic acid of 1.2 dihydroxynaphthalene, to give #-hydroxyquinoneimides which are soluble in alkali. The residual coupling components may then be diazotized and coupled to give desired colours. Some of the emulsions may however, contain phenolic or naphtholic coupling components. Derivatives of aminophenol or aminonaphthol may be used permitting intramolecular coupling after diazotization. (d) The residual coupling component is oxidized to the final dye image. Generators of lignone dye or indigo dyes, or thioindoxyls are used as coupling components. Components for the lowest of three emulsion layers are tetramethoxy-phenyl-alpha-naphtbol, phenyl palmityl pyrazolone, the analogues of 4-methoxyalpha-naphthol (described in Specification 498,870), or 4-ethoxy-alpha-anthrol ; for the middle layer, 2-phenyl-alpha-naphthol, or analogues of 2- methoxy-alpha-naphthol ; and for the upper layer yellow dyes having hydroxyl or other groups, e.g. salicylyl-alpha-aminoanthroquinone. Ferric chloride, alkali bichromates or persurphates or other oxidizing agents, all in acid solution, are used to convert the residual components to lignone dyes. In a second example, the coupling developer gives rise to a soluble coupled dye by containing solubilizing groups, e.g. hydroxyl, carboxylic or sulphonic acid groups. Developers derived from p-amino resorcinol, p-amino-phenol, or p-amino-salicylic acid and containing a p-aminoarylsulphonylamine group, may be used. The dyes are washed out by alkaline solution. 1 : 2-dihydroxynaphthalene-4-sulphonic acid, 4-carbonic acid, and 4-thiosulphonic acid are particularly useful, and yield soluble 2-hydroxyalpha-naphthoquinoneimides. The residual components are converted into the final dye images by the methods previously' described. It is also possible to make complementary coloured negatives by developing first with a neutral non-coupling developer, coupling at the residual silver bromide to yield soluble compounds, and converting the residual uncoupled components into the final image dye. Specification 416,660 is acknowledged. The method is particularly applicable to the multi-layer materials described in Specification 500,826 (as open to inspection under Sect. 91), including mixed grain emulsion layers and material carrying a sound track, preferably in a layer nearest to the support but if necessary in a separate emulsion layer. Specifications 376,794, 376,795, 440,032, 440,089, 447,092, 458,664, 475,784, 475,786, 498,869, 498,870, 498,871, 498,874, 498,875, 499,185, 500,611, 500,717, 500,793, 500,826, 503,752, 503,816, 503,817, 503,818, 503,819, 503,820, 503;821, 503,823, 503,825, 503,826, 503,827, and 503,941 also are referred to. The Specification as open to inspection under Sect. 91 also describes multi-layer materials which are fully described in Specification 500,826 (as open to inspection under Sect. 91). This subject-matter does not appear in the Specification as accepted.