Patent GB-540525-A (GB)
Title: Improvements in and relating to sensitive photographic materials
IPC: G03C1/835
Filed: 1939-12-29
Abstract: 540,525. Photographic light-sensitive materials. POTTS, H. E. (Eastman Kodak Co.). Dec. 29, 1939, Nos. 5549/41 and 5550/41. Divided out of 540,365. [Class 98 (ii)] Multi-layer material comprises at least one emulsion of light sensitive silver salt in a watersoluble binder, such as gelatine, has dispersed therein either 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, preferably solid at ordinary temperatures, or fine discrete oily particles containing the 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, and " 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, amide derivatives, carbonates, esters, ketones, phenol ethers, phosphate esters, sulphonamides and derivatives thereof, sulphones, and ureas. A mixture of dye bodies may be employed. The auxiliary carrier (for solid particles a synthetic resin) and dye bodly 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-immiscible 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. Suitable dyes are azo dyes bleached in the presence of silver image and soluble in organic solvents. Anthraquinone dyes soluble in organic solvents may also be used. In an example, a solution of Oil Red O in tri-o-cresyl phosphate and butyl acetate is poured into water containing "Gardinol" (Registered Trade Mark) and homogenized. The butyl acetate is expelled by heating, and the dispersion diluted with water and added to a positive-type emulsion. Plates coated with this emulsion may be treated after production of a silver image with a dye-destruction bath containing hydrochloric acid, sodium chloride, potassium bromide, dinethylquinoxaline, and 2-hydroxy-3- aminophenazine. The butyl acetate need not be expelled. Plates coated therewith may be processed to colour by the dye-destruction process. The red-sensitized layer may contain particles containing blue-green dye, the green-sensitized layer particles containing magenta dye such as Oil Red O and the blue-sensitive layer particles containing a yellow dye such as benzeneazoresorcinol. Specifications 503,752, 524,554, 524,555, 540,366 and 540,367 are referred to.