Patent GB-488853-A (GB)
Title: Improvements in the production of photographic mono- or multi-colour pictures
IPC: G03C7/28
Filed: 1936-12-08
Abstract: 488,853. Colour photography. I. G. FARBENINDUSTRIE AKT.-GES. Dec. 8, 1936, No. 33687. Convention date, Dec. 11, 1935. [Class 98 (ii)] In the production of mono- or multi-colour photographic pictures using material comprising one or more light-sensitive silver halide emulsions, wherein the colour is formed in at least one emulsion from a dyestuff component present therein before exposure and wherein the dyestuff component or a dyestuff formed therefrom is destroyed at the places of the silver image or at the silver free places, the dyestuff component added to the colloid of the emulsion or to the emulsion contains a residue which is not removed on formation of the dyestuff and renders the dyestuff component, without the addition of a precipitating agent, incapable of being removed from the colloid by washing or by the usual photographic baths. The dyestuff component may contain also a group imparting solubility in water, in particular an acid group in the form of a sodium salt. The component may be added to the layer-forming medium in aqueous solution with or without the addition of organic solvent or an alkali. Dyestuff components such as are described in Specifications 458,400, 465,823, and 479,838 may be employed, and may contain a long chain of conjugated double linkings, for example, the diphenyl nucleus, pyrazolone, triazine, thiazole, oxazole or cyanuric rings, the urea configuration, or fatty residues with at least five carbon atoms. A dyestuff component comprising a leuco compound which is the fatty acid amide of an amidated leuco-compound may be converted into the dyestuff by oxidation after development of the silver image. A quinone imine dyestuff may be made by the action of a nitrosocompound or a quinone on a component such as 1:2-oxynaphthoic acid dibenzidide. An azo-coupling component incapable of diffusion may be coupled with a diazo component after exposure, or both the azo-coupling component and the diazo component may be incapable of diffusion and diazotization may be brought about in the layer by introducing it into a solution of nitrous acid and coupling of the dyestuff effected in the same bath or in a subsequently applied alkali bath. A carrier may be provided with a panchromatic emulsion containing the sodium salt of urea-bis-(3<11>- aminobenzoyl-3<1>-aminobenzoyl-1-amino-8-oxynaphthalene-3 : 6-disulphic acid), an orthochromatic emulsion containing a sodium salt of 1 - (31 - stearylamino) - phenyl - 3 - methyl - 5- pyrazolone, and an emulsion not specially colour-sensitized and containing the sodium salt of di-(acetoacetyl)-benzidine and a yellow filter dyestuff. The material is exposed, developed and introduced into a solution of tetrazotized benzidine-disulphonic acid containing carbon dioxide (for example, a sodium bicarbonate solution acidified with citric acid), whereupon blue-green, purple, and yellow azodyes are produced in the three layers. The dyes are destroyed at the points of the silver image or the layer is tanned at the points of the silver image and the dyes destroyed at the unhardened parts. The dyestuff components may be destroyed by using a stable diazo-compound in the form of a sulphonate, a diazoamino compound, a triazine compound or an anti-diazotate, with or without a coupling component, and converting the compound either directly or indirectly by way of the silver image by oxidation or reduction into a compound such as hydrazine or other scission product incapable of coupling. The dyestuff components may be added to the gelatine for producing the emulsion or during the production of the emulsion or to the finished emulsion. Material may be used having two layers on one side containing azo-dyestuff components fast to diffusion in which the colour pictures are obtained as described above and a single layer on the other side in which the colour picture is produced by toning, colour development or other method. Colour pictures to be viewed by reflected light may be similarly obtained.