Patent GB-503941-A (GB)
Title: Process and materials for colour photography
IPC: G03C7/384
Filed: 1937-07-07
Abstract: 503,941. Colour photography. KODAK, Ltd. July 7, 1937, No. 7952/39. Convention date, July 7, 1936. Divided out of 503,752. 98 (ii)] Process for the production of coloured threecolour photographic records in an element of the kind having three differentially colour sensitized silver halide emulsions inseparably coated on a single support is characterized in that one or more of the emulsions is or are subjected to photographic development with an alkaline coupling developer in the presence of a coupling component having several intracyclic reactive methylene coupling functions in pyrazolone nuclei whereby it can couple with the oxidation products of the developing agent which are formed where a silver image is produced by the development thereby giving rise to a dye image. In a modification the coupling component may be in one or more of the emulsions, the coupling component being not more soluble in the alkali used for the developer than the most soluble of tri-alpha-naphthol triazine, alpha-naphthol-2-carboxylic acid-alpha (or-#)-naphthylamide, alpha-naphthol-4-benzoyl ketone and the hydrazone of the latter. The alkali of the coupling developer may be sodium carbonate or a more weakly alkaline substance. The emulsions may all be coated in three superimposed layers on a single support or may be arranged in a double layer, one layer containing a mixture of silver halide emulsions respectively sensitized for the red and green regions of the spectrum and a second layer containing a not specially colour sensitized silver halide emulsion. Each of the emulsions may contain a coupling component which is insoluble as above defined and each of such coupling components may have several intracyclic reactive methylene coupling functions in pyrazolone nuclei. Bromination of the reactive methylene group makes pyrazolone coupling components more insoluble. The di-pyrazolones made from any of the diesters given in Table II (b) Section A or any of the coupling components containing several pyrazolone nuclei obtainable as,set forth in Tables V(a) and V(b) in Specification 503,752 may be used. Other di- and tri-pyrazolones which may be used are the following: pphenylene-di-(1-phenylpyrazolone), di-phenylmethylpyrazolone, phenylene-bis-(diphenylpyrazolone), di-pyrazolones made from heterocyclic hydrazines, di-pyrazolones derived from di-hydrazines, and tri-pyrazolones obtained from tri-hydrazines. The three-colour photographic element may have a layer of colloidal silver in any emulsifying medium permeable to water on either side of the support to serve as anti-halation protection. The element may carry a sound track contained in an almost grainless silver halide emulsion forming a fourth layer and sensitized for infra-red. Specifications 500,826 (as open to inspection under Sect. 91), 376,746, 376,794, 576,795, 440,032, 440,089, 447,092, 458,664, 464,398, 475,784, 475,786, 482,290, 498,869, 498,870, 498,871, 498,875, 499,185, 503,752, 503,816, 503,817, 503,818, 503,819, 503,820, 503,821, 503,823, 503,824, 503,825, 503,826, 503,827, and 503,940 also are referred to. Reference has been directed by the Comptroller to Specifications 455,556, 468,946, and 479,838.