Patent GB-784479-A (GB)
Title: Process of colour development in photography and light-sensitive emulsions and colour-forming developers therefor
IPC: G03C7/32
Filed: 1956-01-05
Abstract: 784,479. Photographic colour develop ment. KODAK. Ltd. Jan. 5. 1956 [Feb. 17, 1955], No. 384/56. Drawings to Specification. Class 98(2) A reducible silver salt image in a photographic emulsion is developed with a primary aromatic amino developing agent in the presence of an image-forming colour coupler which gives dye image substantiallv insoluble in the processing solutions employed and of a competing coupler which gives a dve capable of substantial removal by washing without causing substantial diffusion of the image dye, the competing coupler having the general formula wherein.R is OH, alkoxy or NH2 (which may be substituted), R 1  and R 2  are H or acyl, X and Y represent the carbon atoms necessary to complete a 6-membered ring, and Z is N or CH. The image coupler may be incorporated in the emulsion, with the competing coupler either in the emulsion or the developing solution, or both the image coupler and the competing coupler may be incorporated in the developing solution. The competing coupler may be incorporated in a colloid layer contiguous to the emulsion layer. Competing couplers specified include 2 : 6 - dihydroxyisonicotinic acid and 3 : 5 - dihydroxybenzoic acid, their methyl, butyl, and dodecyl esters, benzyl 2 : 5 - dihydroxyisonicotinate, 2 : 6 - dihydroxy - N - (2 - hydroxyethyl)- isonicotinamide, 3 : 5 - dihydroxybenzamide, 3 : 5 - dilauroyloxybenzoic acid, 2 : 6 - dihydrorxy - 3 - chloroisonicotinic acid, and 2 - chloro 3 : 5 - dihydroxybenzoic acid. In Example 1, a film support is successively coated with a red-sensitized silver halide emulsion containing 2 - (2 : 4 - di - tert. - amylphenoxyacetamido) - 4 : 6 - dichloro - 5 - methylphenol, a thin gelatin layer, a green-sensitized emulsion containing 1 - (2<SP>1</SP> : 4<SP>1</SP> : 6<SP>1</SP> - trichlorophenyl) - 3 - [3<SP>11</SP> - (2<SP>111</SP> : 4<SP>111</SP> - di - tert. - amylphenoxyacetamido) - benzamido] - 5 - pyrazolone. a yellow filter layer containing colloidal silver ,and a blue-sensitive emulsion containing N - (4 - benzoylacetaminobenzenesulphonvl) - N - (y - phenyl - n - propyl.)- p - toluidine, all of the couplers being incorporated by the method of Specification 541,589 and each of the emulsions containing N - ethyl : N - (# - methanesulphonwould be used in a reversal film intended for normal processing. Two portions of the material are exposed. developed in a black- and-white developer, rinsed, hardened. given a reversal exposure. washed, and colour developed in colour developers containing N - ethyl: N - # - methanesulphonamidoethyl) - 3 - methyl - 4 - aminoaniline sulphate as the developing agent, one such developer containing 2 : 5 - dihydroxyisonicotinic acid as the competing coupler and giving cyan, magenta and yellow dye images in the finished film of desired lower contrast. In Example 2, two portions of a film having a single-layer two-colour mixed packet coating prepared by the method of Specification 711,488 and capable of development to produce cyan and magenta images are exposed and colour developed in developers containing 2 - methyl - 4 - dimethylaminoaniline as developing agent, one of which contains 2 : 6 - dihydroxyisonicotinic acid as competing coupler. The competing coupler tends to prevent wandering of oxidized developing agent through the matrix from packet to packet. In Example 3, exposed portions of a film carrying a silver bromiodide emulsion containing 2 - (2 : 4- di - tert. - amylphenoxyacetamido) - 4 : 6- dichloro - 5 - methylphenol is colour developed in a colour containing no competing coupler and in similar colour developers containing various competing couplers, the silver density increases and the dye density decreases being given. The compounds 2 : 3 - and 2 : 4 - dihydroxybenzoic acids, 4 - (o - carboxybenzoyl) - resorcinol, salicyclic acid, m - hydroxybenzoic acid, 4 - n - propyl - 2 : 6 - pyridinediol, 2 - carboxy - 5 - ethoxyphenol. 2 - amino - 6 - hydroxypyridine sulphate, and 5 - acetamido - 2 - carboxyphenol show little activity as competing couplers. More soluble competing couplers mav be incorporated into emulsions as their alkali metal salts, and the competing couplers may be dispersed in emulsion lavers bv the methods of Specifications 524,154, 524,554. 524,555. or 541,589. Esterified comneting couplers become hydrolyzed in the development process. The image couplers mav be coloured as described. in Specifications 599,377 and 617,247, and the process of the invention may be anplied to mixed-grain materials as described in Specifications 662,360 and 670,457. The process may also be applied in the production of monochrome fine-grain dye images by colour development, and an image coupler producing a substantially neutral grey dye image may be employed. Specification 755,655 also is referred to.