Patent GB-503814-A (GB)
Title: Improvements in three-colour photographic materials
IPC: G03C7/30
Filed: 1937-07-07
Abstract: 503,814. Colour photography. KODAK, Ltd. July 7, 1937, No. 2598 /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 of which the upper emulsion layer is sensitive to blue-violet light, themiddle emulsion-layer to red and orange light, and the lower emulsion layer to yellow and green light, and is characterized in that each of the emulsions contains a coupling component which is insoluble in water or in aqueous sodium carbonate solution. 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-benzoyl-ketone, and the hydrazone of the last named, and couple with the oxidation products of the developing agent formed where a silver image is produced by the alkaline coupling developer. The components may have different coupling speeds, one coupling in presence of borax and the other in presence of sodium carbonate. Each emulsion may be treated separately with coupling developers 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 sodiumcarbonate-soluble colloid, such as dextrine, gum arabio, 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 densityvariable 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 the bottom emulsions. The filter colours may be added to the top and the middle emulsion layers. Strongy swelling gelatine is used for the emulsion and 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 lessswelling colloids, may be used. The use of peptised and centrifuged silver bromide emulsions is referred to. Elements having top blue-violet sensitive emulsion layer, a middle yellow and green sensitive layer, and a bottom red sensitive layer, and having a top red sensitive layer, a middle yellow-green sensitive layer, and a bottom blue-sensitive layer are 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. 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.