Patent GB-543606-A (GB)
Title: Improvements in colour photography
IPC: G03C7/388
Filed: 1940-06-03
Abstract: 543,606. Photographic light-sensitive material. MARTINEZ, M. June 3, 1940, No. 9657. [Class 98 (ii)] Photographic sensitive material comprises a light sensitive emulsion whose sensitivity resides in sensitive silver salt grains dispersed in a binder such as gelatine and having within such grains a water-insoluble binder such as a resin or gum incorporated during the formation of the grains by precipitation of the silver salt in the presence of a water solution of the binder or during ripening of the grains. The silver salt may be a halide and the grains may be dispersed in gelatine and may also contain a dye body, i.e. a dye, dye-derivative. leuco dye, or dye-forming substance such as a colour coupler. The resin or gum or water-insoluble water-permeable binder may be coloured to act as a light filter for the grains. Colour photographic three-emulsion material may have at least one emulsion of the type defined, and the grains of each emulsion may contain a dye body. An emulsion may consist of a mixture of two or three sets of differentially colour sensitive grains containing dye bodies. A set of grains containing a resin or gum or water-insoluble water-permeable binder and a dye body may be dispersed in a differently sensitized emulsion containing another dye body. A three-emulsion material may comprise a non- colour sensitized emulsion containing a dye body in which are dispersed two sets of grains of the type specified and sensitized to red and green respectively, the sets of grains containing different dye bodies. The grains may be produced by precipitation of a silver salt in the presence of the resin or gum or water-insoluble water-permeable binder and also of the dye body. A solution of a halide containing gelatine may be mixed with a solution of silver nitrate, one or both solutions containing the resin, gum, or water-insoluble water-permeable binder. Resins referred to are amber, dragon's blood, gum ammoniacum, oxidized guaicum, shellac, gum gutte, gum kino, benzoin, mastic, colophony, sandarach, dammar, polyvinyl esters or acetals, polyvinyl alcohol condensed with polybasic acids, alkyd resins, polystyrene resins, and the resins formed by condensing formaldehyde or phenol alcohols with phenols, oxy-, aryloxy, or alkyloxy-carboxylic acids, or phenoxy fatty acids (which resins may be modified by treatment with halogen fatty acids or the condensation products of phenols or phenol carboxylic acids with aliphatic, aromatic, or heterocyclic aldehydes or thionyl chloride). Mixtures of resins with rubber latex or with synthetic rubbers or with organic acid esters and a cellulose derivative may also be employed. Emulsions containing the grains may be used in the production of multilayer material, mixedgrain material, bi- and tri-packs, and material for producing separate colour component records. The grains may differ in sensitivity, contrast, and resolving power. Colour formers, metal salts, sensitizers, and colouring matters may be incorporated in the grains. The grains may be made by preparing two separate alcoholic solutions, one of a halide such as the chloride or bromide of ammonium, lithium, zinc, strontium, calcium, gold, or barium, and the other of an equivalent amount of silver nitrate. A resin is dissolved in either or both solutions, and substances such as citric, tartaric, or phosphoric acid, may also be added to either or both solutions. Colour formers such as alphanaphthol or 1-phenyl-3-methyl-5-pyrazolone, colour sensitizers, colouring matters, and plasticizers such as castor oil, glycerine, amyl acetate, triacetin, and tri-cresyl phosphate may be added at the time of mixing the solution or afterwards. Alternatively the support may be first coated with a solution of a halide with resin in a volatile solvent or in alkali, and then coated with a solution of silver nitrate, which may be in water and contain an acid, preferably organic, to neutralize any alkalinity present. In a mixed-grain emulsion, resins of differing solubility are used. The silver nitrate may be dissolved in alcohol and added to the solution of the resin in its particular solvent. One batch of emulsion may be made using benzoin or shellac in alcohol or dragon's blood in ethyl acetate, a second batch using gum sandarach in acetone, and a third using gum mastic or dammar in benzene. Three colour component records may be made on single layers on separate supports, and after processing drying, and registering the layers may be caused to adhere by warming, the resins acting as the adhesive. A dispersion of silver halide in a resin may be dispersed in gelatine. A dye to act as a light filter may be dissolved in the alcohol or other solvent used in the preparation of the resin-silver halide emulsion. Coloured metal salts or organic compounds thereof may also be used for this purpose. In the preparation of the emulsion, one solution may comprise a halide and a resin in an alcoholic solvent, and the other silver nitrate, gelatine, and ammonia. The latter solution may be divided into two, one with and the other without ammonia to control contrast. One portion of the silver nitrate may be added to the gelatine solution and the other after mixing. Colour formers may be added to one of the solutions before precipitation of the silver halide. Emulsions to be used in making a mixed-grain emulsion should be separately well-washed before melting and mixing. Three solutions may be used, one of gelatine in water, a second of halides with or without organic acids or salts thereof in alcohol or water, and a third of resin and silver nitrate in an alcoholic solvent. The resin may be in the second solution, in which case the silver nitrate may be in aqueous solution. Two solutions may be poured simultaneously into water, a thickening agent being present in the water. After precipitation, washmg, and drying, the grains are dispersed in any suitable binder, including binders such as collodion or regenerated cellulose. The resin may be employed in the form of a sodium, potassium or other water-soluble resinate, which may be incorporated in the halide solution so that silver halide and insoluble metal resinate are simultaneously produced. Alternatively an acid may be added to reform the resin from the salt. The different resins used in multi-emulsion material may have different resistance to alkaline or acid treatment, different solubility in the same solvent, or different water permeability. The colours produced may be correct or false. The relative proportions of the various grains are adjusted to produce materials suitable for exposure in daylight or in artificial light. Colour photographic material may comprise a single layer containing a mixture of three sets of grains; three layers of grains, all on one side or distributed between both sides of a support; one layer containing one set of grains and another containing a mixture of two sets of grains; a mixed-grain layer (two or three sets of grains) placed over an ordinary emulsion layer intended to produce a black image; or a dispersion of one or two sets of grains in an emulsion suitable for producing a black or coloured image. including a two-layer material in which one layer comprises a dispersion of one set of grains in an emulsion for producing a coloured image, and the other a dispersion of another set of grains in an emulsion for producing a black image. The red-recording grains may be sensitized to a red sensitivity much higher than their natural blue sensitivity by forming the silver halide grains in the presence of a nickelous salt and subsequently sensitizing with pinacyanol. Silver halide grains having a much higher green sensitivity than their natural blue sensitivity may be similarly produced using a cobaltous salt and subsequently sensitizing with pinaverdol, erythrosine, or orthochrome T. Alternatively the nickelous or cobaltous salt may be incorporated in the solution of the sensitizer. A yellow dye may be incorporated in the grains. The selective sensitivities of the various grains may be improved by treating all the grains with an alcoholic solution of isamine blue (Pyrrol Blue). A decolourisable yellow filter may be incorporated in the gelatine or ordinary emulsion in which the red- or greensensitive grains are dispersed. The colour formers may give dyes by oxidation, reduction, or diazotization, or may give the required colours with the same developer, or with different developers each reacting only with one colour former. Alternatively a single colour former reacting differently with different developers may be used, or one set of grains only may contain a colour former, a developer being used which produces one colour in conjunction with the colour former, and another colour by itself. Metal salts present in the grains may be used to mordant dyes or to produce coloured metal salt images. A silver image may be toned to a yellow image containing nickel by means of a solution containing a nickel salt, e.g. nickelous chloride, an alkali ferricyanide and an alkali or ammonium salt of an organic acid, e.g. citric, oxalic, or tartaric acid. The nickel containing image, e.g. nickel ferricyanide or oxalate images, may be further toned, e.g. to magenta with dimethylglyoxime, to purple with rubeanic acid, to orange with alphafurildioxime, to yellow with alphafurildioxime mixed with salicylaldioxime, to red with ammonium aurinetricarboxylate, to yellow with diphenylcarbazide, to violet with diphenylcarbazone, or to blue with benzidine, the compounds being used in a weak sodium carbonate solution, containing a little sodium sulphite. A silver image may also be toned to an image containing cobalt, which may likewise be further toned. The metal salt images may be dyed. The controlled penetration process may be used in conjunction with metal or dye toning, with colour development, or with the process known under the Registe