Patent GB-540365-A (GB)
Title: Improvements in and relating to photographic materials
IPC: G03C7/388
Filed: 1939-12-29
Abstract: 540,365. Photographic light-sensitive materials. POTTS, H. E. (Eastman Kodak Co.). Dec. 29, 1939, Nos. 32966 and 33067. Drawings to Specification. [Class 98 (ii)] A light-sensitive photographic material has inseparably coated in a single support several differentially light-sensitive silver salt emulsions for subtractive three-colour photography and at least one non-sensitive layer of water-soluble colloid such as gelatine having dispersed therein fine discrete particles of an auxiliary carrier having dissolved or dispersed therein a dye body, such as a pigment dye, leuco dye, or dye,derivative, or having dispersed therein fine, discrete oily particles containing dye body. The auxiliary carrier is substantially water-insoluble and may be a solid, a liquid, or a mixture thereof. Carriers specified are cellulose derivatives, such as esters or ethers, gums, resins, synthetic resins, or " oil formers," i.e. substances giving liquid particles, such as liquids or solids of low melting-point, preferably containing polar groups such as halogen atoms, or hydroxyl, carboxylic acid, amide or keto groups. A mixture may be employed as auxiliary carrier. The auxiliary carrier is preferably removable in processing. Numerous oil formers are specified including acids, alcohols, amides, imides, carbamates, esters, ketones, phenol ethers, phosphate esters, sulphonamides and derivatives thereof, sulphones, and ureas. A mixture of dye bodies may be employed. The auxiliary carrier dye body may be dissolved in a common solvent immiscible with gelatine emulsion, and either dispersed in the emulsion directly or first dispersed in water containing a wetting agent. The mixture may be coated as such or the waterimmiscible solvent first removed. Alternatively, the dye body and auxiliary carrier may be dissolved in a water-miscible solvent and added directly to the colloid solution, or a solution in a volatile solvent may be spray dried. Lightscatter may be avoided by varnishing the surface with a preferably waterproof material whose refractive index does not differ greatly from either the dispersed particles or the water soluble binder. Protruding particles may be removed by treatment with a solvent. Internal light-scatter is avoided by incorporating either in the watersoluble binder or in the auxiliary carrier a substance bringing the refractive indices of the binder and carrier into closer approximation. The preferred dyes are those having in the non-salt form relatively low solubility in water and high solubility in organic solvents and forming watersoluble salts with acids, alkalies, or both. Methyl red and other suitable azo dyes, pyhrole, and oxonol dyes are referred to. A solution of a filter dye in a mixture of tri-o-cresyl phosphate and butyl acetate is added to water containing " Gardinol " (Registered Trade Mark), and run through a colloid mill. The dispersion, with or without prior removal of the butyl acetate, is added to 5 per cent gelatine solution and coated as a underlayer or intermediate layer in multilayer material. In an example, 2-hydroxy-5- methoxy-azobenzene is added to a solution of gum mastic in acetone and methyl alcohol, and the solution added to a 6.5 per cent gelatine solution. The resulting dispersion may be coated as a yellow filter layer in multi-layer material. In a second example, a butyl acetate solution of cellulose nitrate, ethyleneglycol monobenzyl ester, and benzeneazocresol is emulsified in an aqueous solution of " Gardinol ", the butyl acetate is expelled by heating, and the suspension added to a 6.5 per cent gelatine solution. In a third example, a solution of methyl red in butyl acetate and N-butyl pythalate is emulsified in an aqueous solution of " Gardinol ", and the resulting dispersion added to a 6.5 per cent gelatine solution. The invention may be applied in the production of multi-layer material or in the production of antihalation layers. Multi-layer material of the kind having blue, green, and red-sensitive emulsion layers has a yellow filter between the blue and green sensitive layers and if desired a yellow or red filter layer between the green and redsensitive emulsion layers. The filters are made according to the invention. Specifications 503,752, 506,385, 524,554, 524,555, 529,440 and 540,367 are referred to.