Patent GB-698047-A (GB)
Title: Colour photography
Inventor: GANGUIN KARL OTTO
IPC: H01J13/48
Filed: 1950-11-20
Abstract: 698,047. Colour photography. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Nov. 19, 1951 [Nov. 20, 1950], No. 28301/50. Class 98 (ii). Colour photographic material comprises three differently-sensitized gelatino -silver halide emulsion layers containing yellow, magenta, and cyan colour couplers superimposed on a support, one of the outermost sensitive layers being blue-sensitive only and adjacent to and not separated by a filter layer from the middle sensitive layer which contains a non-diffusible yellow styryl dye, e.g. containing an alkyl chain of at least 5 carbon atoms, obtainable by condensing a reactive methylene compound with an anil of a water- or alkali-soluble aldehyde of the formula wherein the benzene nucleus may be substituted and wherein at least one of the radicals R 1  and R 2  is an alkyl radical substituted with halogen, -CN, -COO-alkyl, -NO 2 , or a carboxylic or sulphonic acid group, and, when only one of the radicals R 1  and R 2  is an alkyl radical so substituted, the other is a substituted or unsubstituted hydrocarbon radical. Numerous reactive methylene compounds and aldehydes are specified. If the bottom layer is blue-sensitive, the material is exposed through the support. The middle layer may be green-sensitive and the bottom layer red-sensitive, or vice versa. The styryl dye is largely decolourized during development, and completion of decolourization may be effected by treatment with hydrazine hydrate, e.g. added to the fixing bath, as described in Specification 695,875. The styryl dye may serve as magenta colour coupler, and a small proportion of a colourless magenta coupler may be added to the middle layer to modify the spectral absorption of the magenta dye obtained. Alternatively, the middle layer may contain a mixture of a yellow styryl dye as above defined and a yellow styryl dye derived from a reactive methylene compound and a water- and alkali-insoluble p-N-substituted aminobenzaldehyde. After development, bleaching, and fixing, a yellow colour correction mask may be formed in the middle layer by treatment with formaldehyde or sodium nitrite, as described in Specification 698,046, the anils formed by reaction with the developing agent from the aldehydes liberated by the developer are decomposed and react with the reactive methylene compound to reform yellow styryl dye, mainly in the non-image parts of the layer. In example 1, paper is successively coated with a red-sensitive gelatino-silver halide emulsion layer containing 1-hydroxy-4- sulpho-2-naphthoyloctadecylamide, a gelatine layer, a green-sensitive gelatino-silver halide emulsion layer containing 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>- sulphophenyl)-3-heptadecyl-4-p-N: N<SP>1</SP>-di-(carboxyethyl) - aminobenzylidene - 5 - pyrazolone, a gelatine layer, and a blue-sensitive emulsion layer containing the sodium salt of p-stearylaminobenzoylacetanilide - p<SP>1</SP> - carboxylic acid. The paper is exposed through a subtractivelycoloured negative transparency, colour developed in a developer including hydroxylamine hydrochloride, rinsed, treated in an acetic acid-sodium acetate stop bath, washed, bleached, washed, and treated in a fixing-dye discharge bath including hypo and hydrazine hydrate. In example 2, a transparent support is successively coated with a red-sensitive emulsion layer containing sulphonated 1- hydroxy - 2 - naphthoyloleylamide, a greensensitive emulsion layer containing a mixture of 1 (41 - phenoxy - 3<SP>1</SP> - sulphophenyl) - 3 - heptadocyl - 4 - p - di - (# - cyanoethyl) - aminobenzylidene - 5 - pyrazolone sodium salt and 1-(41- phenoxy - 3<SP>1</SP> - sulphophenyl) - 3 - heptadecyl - 4 -p) - di - (carboxyethyl) - aminobenzylidene - 5 - pyrazolone sodium salt, and a blue-sensitive emulsion layer containing the sodium salt of p-stearylaminobenzoylacetanilide-p<SP>1</SP>-carboxylic acid. The exposed material is colour developed, washed, bleached, washed, fixed, and treated with sodium nitrite solution to produce a reversed yellow colour correction image from the styryl dye derived from the insoluble aldehyde. In example 3, the procedure is similar to that of example 1, but the yellow styryl dye used is the sodium salt of 1-#-octadecenylsuccinamido - 4 - # - cyano : # . (p - N: N di - (carboxyethyl) - aminobenzylidene - acetobenzene. In example 4, the middle emulsion layer contains the yellow styryl dye of example 3 and also the colour coupler 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>-sulphophenyl) - 3 - heptadecyl - 5 - pyrazolone (sodium salt). Specifications 465,823 and 486,848 also are referred to.