Patent GB-503939-A (GB)
Title: Improvements in three-colour photographic materials
IPC: G03C7/30
Filed: 1937-07-07
Abstract: 503,939. Colour photography. KODAK, Ltd. July 7, 1937, No. 2599/39. Convention date, July 7, 1936. Divided out of 503,752. [Class 98 (ii)] A three-colour photographic element has three silver halide emulsion layers inseparably coated on a single support, the top layer being blue-violet sensitive, the middle layer yellow and green sensitive, and the bottom layer red sensitive, and is characterised in that each emulsion contains a coupling component insoluble in water or a solution of sodium carbonate in water. The coupling components are not more soluble than the most soluble of the following, viz., tri-alpha-naphthol triazine, alpha-naphthol-2-carboxylic acid-alpha-(or #)-naphthylamide, alpha-naphthol-4-benzoylketone, and the hydrazone of the last-named, and couple with the oxidation products of the developing agent formed where the silver image is produced by the alkaline coupling developer. Components may have different coupling speeds one coupling in the presence of borax and the other 'in presence of sodium carbonate. Each emulsion may be treated separately with coupling components of different coupling speed. The components may be finely dispersed in 10 per cent gelatine solution and the latter added to the gelatine silver halide emulsion. The components may be deposited on or adsorbed by the silver halide grains, or may be formed. 'within the emulsion, preferably after ripening, or may be precipitated in emulsions of low gelatine content and gelatine added, or may be precipitated in centrifuged silver bromide emulsion or in silver bromide separated from a gelatine emulsion and dispersed in water or glycerine or other inert water-miscible liquid, and the resulting material dispersed in gelatine, washed and sensitized The components may be added in alcoholic alkaline solution to a silver halide emulsion and precipitated by acid. A yellow filter consisting of dyed water or sodium carbonate-soluble colloid, such as dextrine, gum arabic, or stearic acid, may be arranged in front of the top emulsion layer, and a colloidal silver anti-halation layer may be arranged on either side of the support. A primary or reversed sound record may be printed in one, two, or three layers of the material before or after colour processing, or may be in a fourth infra-red sensitized layer, in which case printing of the sound record may be effected from the back. Printing may be effected at any stage of the process after drying the element. A variable area or combined variable density-variable area sound record may be used. The material may be processed by primary colour development, or by development, fixing, bleaching, and colour development, or by reversal colour development. A yellow filter may be arranged between the top and middle emulsion layers, and a yellow, a green, or a red-orange filter, or a colourless gelatine layer between the middle and bottom layers. The filter colours may be added to the top and the middle emulsion layers. The filter colours may be added to the top and the middle emulsion layers. Strongly swelling gelatine is used for the emulsion andthe filter layers. The emulsion layers may be coated on the support in reverse order and exposed through the support. A highly sensitized collodion emulsion may be used for the bottom emulsion, and the support may be of cellulose acetate, regenerated cellulose, or other synthetic colloid, or a hardened gelatine emulsion, including one in which part of the gelatine is replaced by agar-agar, polyvinyl alcohol, or other less-swelling colloids, may beused. The use of peptised and centrifuged silver bromide emulsions is referred to. The original latent images may be developed with ferrous oxalate or hydroquinone-acetone sulphite, and the residual silver halide made developable by a fogging agent such as thiosinamine. Elements having a top blue-violet sensitive layer, a middle red and orange sensitive layer, and a bottom yellow and green sensitive layer, and having a top red sensitive layer, a middle yellow-green sensitive layer, and a bottom blue-sensitive layer are referred to. Specifications 376,746, 376,794, 376,795, 440,032,440,089, 447,092, 499,185, 500,826 (as open' to inspection under Sect. 91), 503,752, 503,816 503,817, 503,818, 503,819, 503,820, 503,821, 503,823, 503,824, 503,825, 503,826, 503,827, 503,940, and 503,941 are referred to. Referenee has been directed by the Comptroller to Specifications 465,823 and 468,946.