Patent GB-695875-A (GB)
Title: Photographic process
Inventor: GANGUIN KARL OTTO
IPC: G03C1/83
Filed: 1950-06-15
Abstract: 695,875. Colour photography. IMPERIAL CHEMICAL INDUSTRIES, Ltd. June 15, 1951 [June 15, 1950], No. 14946/50. Class Class 98 (ii). An exposed multilayer colour photographic material comprising differently colour sensitized silver halide emulsion layers, at least one filter layer containing a yellow non-diffusible styryl dye, is developed and the filter layer is subsequently decolorized by treatment with an aqueous solution of an amino compound of the formula R-NH 2 , wherein R is an alkyl, aralkyl, amino, alkylamino, aralkylamino, arylamino, aminoalkylene or hydroxy group. The styryl dye may be non-diffusible owing to its molecular structure or owing to treatment with a precipitating agent or owing to the method of forming the coating composition. The solution of the amino compound preferably also contains a surface-active agent, e.g. a condensation product of a phenol or alkylphenol with ethylene oxide, a condensation product of an aliphatic alcohol, e.g. cetyl alcohol, with ethylene oxide, an alkylated sulphonated aromatic hydrocarbon, or a quaternary ammonium salt containing a long alkyl chain, e.g. cetyltrimethylammonium bromide. The free amino compound may be formed in situ by adding alkali to a salt thereof, but a preformed free amino compound or hydrate thereof, e.g. an aqueous solution of ethylene diamine, 4- sulphophenylhydrazine or hydrazine hydrate is preferably used. The material may be subsequently treated with a dilute alkali solution. The styryl dye may be one formed by condensing a reactive methylene compound with an anil of a substituted benzaldehyde, preferably containing solubilizing groups. Numerous substituted benzaldehydes are specified, and the reactive methylene compound may be 1-#- octadecenylsuccinamido - 4 - w - cyanoacetbenzene, a thioindoxyl, 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>-sulphophenyl) - 3 - heptadecyl - 5 - pyrazolone, 3- heptadecyl- 5 - pyrazolone, or 1 - (31 - carboxyphenyl) - 3 - p - stearamidophenyl - 5 - pyrazolone. A soluble salt of the dye may be incorporated in a gelatin solution and the composition coated as a filter layer. Diffusible dyes may be precipitated, e.g. with a high molecular weight base, in the gelatin, or may be dissolved together with a water-insoluble waterpermeable resin, e.g. polyvinyl acetate in a volatile organic water-miscible solvent, and the solution dispersed in the gelatin and the solvent evaporated off. In example 1, a support is successively coated with a red-sensitive emulsion layer containing the sodium salt of 1- hydroxy - 2 - naphthoylamino - 2<SP>1</SP> - (methyloctadecylamino) - benzene - 5<SP>1</SP> - sulphonic acid, a green-sensitive emulsion layer containing the sodium salt of 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>-sulphophenyl)- 3 - heptadecyl - 5 - pyrazolone, a yellow gelatin filter layer containing the sodium salt of 1- (41 - phenoxy - 31 - sulphophenyl) - 3 - heptadecyl - 4 - p - N - methyl : N - # - sulphoethylaminobenzylidene) - 5 - pyrazolone, and a blue-sensitive emulsion layer containing the colour coupler described in example 3 of Specification 486,848. After exposure, colour development, rinsing, treating in a stop bath consisting of an aqueous solution of potassium dihydrogen phosphate, washing, removing silver, washing, fixing, and again washing, the filter layer is decolorized by treatment in an aqueous solution of hydrazine hydrate containing a condensation product of octyl cresol with about 10 molecular proportions of ethylene oxide or with an aqueous solution of ethylene diamine or with a solution obtained by adding aqueous ammonia to aqueous hydroxylamine hydrochloride. In example 2, the material and procedure are similar, but the filter layer is decolorized by treatment in an aqueous solution of sodium thiosulphate and hydrazine hydrate. In example 3, the material is similar, except that the filter layer contains as the dye the sodium salt of 1-#-octadecenylsuccinamido- 4 - w - (p - - p : #<SP>1</SP> - di - carboxyethyl) - aminobenzylidene) - # - cyanoacetobenzene, and the decolorization is effected as in example 2.