Patent GB-698046-A (GB)
Title: Process for colour photography
Inventor: GANGUIN KARL OTTO
IPC: G03C1/83
Filed: 1950-11-20
Abstract: 698,046. Colour photography. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Nov. 19, 1951 [Nov. 20, 1950], No. 28300/50. Class 98 (ii). Colour correction is effected in colour photography by developing with an aromatic amine colour developer an exposed multi-layer material comprising three differently colour sensitized gelatino silver halide emulsion layers containing yellow, magenta, and cyan couplers, the magenta coupler being a water-soluble yellow styryl dye which contains a substituent rendering the dye fast to diffusion and which is derived from a p-N-substituted aminobenzaldehyde and a reactive methylene compound, and by subsequently treating the material with a substance capable of liberating the p-N- substituted aminobenzaldehyde from the p-N- substituted aminobenzylidene derivative of the aromatic amine used as colour developer. The substance used may be formaldehyde or a nitrite. In the unexposed parts of the layer containing the yellow styryl dye, the aromatic amine used as colour developer reacts with at least part of the dye to form the parent reactive methylene compound and the anil derived from the parent p-N-substituted aminobenzaldehyde and the aromatic amine, and treatment with formaldehyde or a nitrite liberates the aldehyde from the anil and permits sufficient yellow styryl dye to be reformed to provide a yellow masking positive image. Where the parent aldehyde is free from solubilizing groups and the parent reactive methylene compound is non-diffusible, substantially all of the yellow styryl dye will be reformed. Numerous suitable parent p-N-substituted aminobenzaldehydes are specified, and the parent reactive methylene compound may be 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>- sulphophenyl) - 3 - heptadecyl - 5 - pyrazolone, 1 - (phenyl - 31 - methanesulphonic acid) - 3 - heptadecyl - 5 - pyrazolone, or 1 - # - octadecenylsuccinamido - 4 - # - cyanoacetobenzene. The multilayer material may have a yellow colloidal silver filter layer between the top bluesensitive emulsion layer and the middle green- or red-sensitive emulsion layer, or the filter layer may contain a yellow styryl dye derived from an aldehyde containing a water-solubilizing group. In the latter case, the styryl dye used as colour former should be derived from an aldehyde free from water-solubilizing groups, and after colour development and treatment in a stop bath, the material may be treated with hydrazine, e.g. in the fixing bath, to discharge the filter dye and washed to remove one or more of the decomposition products of the dye before treating with formaldehyde or sodium nitrite to regenerate the styryl dye masking image. Where the yellow stearyl dye forming the magenta coupler is incorporated in the middle emulsion layer, the yellow filter styryl dye may also be incorporated in this layer. In example 1, a transparent supported is successively coated with a red-sensitive gelatino silver halide emulsion layer containing as cyan coupler sulphonated 1-hydroxy-2-naphthoyloleylamide, a green-sensitive emulsion layer containing 1 - (41 - phenoxy - 31 - sulphophenyl) - 3 - heptadecyl - 4 - p - # : #<SP>1</SP> - dicyanodiethylaminobenzylidene-5-pyrazolone (sodium salt), a colloidal silver-gelatine filter layer, and a blue-sensitive gelatino silver halide emulsion layer containing the sodium salt of p-stearylaminobenzoylacetanilide-p-carboxylic acid. After exposure and colour development, the rinsed film is treated in a stop bath containing acetic acid, sodium acetate, and formaldehyde, in a bleaching bath containing potassium ferricyanide, potassium bromide, and sodium dihydrogen phosphate, and in a fixing bath to provide in the three layers cyan, magenta, and yellow negative dye images respectively and in the middle layer a yellow positive styryl dye masking image. In example 2, the colloidal silver filter layer is replaced by a gelatine layer containing the styryl dye 1 - # - octacecenylsuccinamido - 4 - # - cyano: # - (p - - N: N - di - (carboxyethyl) - aminobenzylidene)-acetobenzene (sodium salt). After exposure and colour development, the film is treated in an acetic acid-sodium acetate stop bath, the silver bleached, the film treated in a hypo fixing bath containing hydrazine hydrate to decompose the styryl dyes, the film washed to remove the soluble decomposition products of the filter dye, and treated with aqueous formaldehyde to regenerate the yellow styryl dye positive masking image. In example 3, the material is similar, but the middle greensensitive emulsion layer contains two styryl dyes, viz. the sodium salts of 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>- sulphophenyl) - 3 - heptadecyl - 4 - p - di - (ethylcarboxymethyl) - amino benzylidene - 5 - pyrazolone and of 1-(4<SP>1</SP>-phenoxy-3<SP>1</SP>-sulphophenyl)-3- heptadecyl - 4 - p - di - (carboxyethyl) - aminobenzylidene - 5 - pyrazolone. After exposure, colour development, washing, and fixing, the material is treated with an aqueous solution of sodium nitrite to regenerate the first but not the second styryl dye in the non-image areas to provide a yellow styryl dye positive masking image. In example 4, the material is similar to that of example 1, but the styryl dye used as magenta coupler is 1-(phenyl-31-methanesulphonic acid) - 3 - heptadecyl - 4 - p - # : #<SP>1</SP> - dicyanodiethylaminobenzylidene - 5 - pyrazolone (sodium salt) or 1 - (phenyl - 3<SP>1</SP> - carboxylic acid) - 3 - (41 - stearoylaminophenyl) - 4 - p - di - (ethylcarboxymethyl) - aminobenzylidene - 5 - pyrazolone. In example 5, the material is similar to that of example 2, but the stearyl dye used as magenta coupler is the sodium salt of 1 - # - octadecenyl - succinamido - 4 - # - cyano : # - (p - N - methyl: N - # - cyanoethylaminobenzylidene)-acetobenzene. In example 6, the first dye of example 3 is replaced by the sodium salt of 1-phenyl-3-(#-octadecenylsuccinamido)- 4 - P - # : #<SP>1</SP> - dicyanodiethylaminobenzylidene - 5 - pyrazolone or 1 - p - cyanophenyl - 3 - (# - octadecenylsuccinamido) - 4 - p - - N - # - chloroethyl: N - methylaminobenzylidene - 5 - pyrazolone. Specifications 465,823, 486,848, 513,596, 673,091 and 698,047 are referred to.