Patent GB-728769-A (GB)
Title: Improvements in and relating to subtractive colour photography
IPC: G03C7/333
Filed: 1952-11-03
Abstract: 728,769. Colour photography. KODAK, Ltd. Nov. 3, 1952, No. 27574/52. Drawings to Specification. Class 98 (2). Masking images are formed in a falsesensitized photographic colour material comprising red, green and blue-sensitive silver halide emulsion layers coated in that order on a support, each layer containing a colourcoupler which on colour development produces a subtractive dye image at least two of which images are of a colour other than that which is complementary to the sensitivity of the layer in which it is formed, by using in the bluesensitive layer, either a coupler which is yellow in its uncoupled state and couples to give a magenta image, or a coupler which is orange or yellow in its uncoupled state and couples to give a cyan image, the uncoupled residue being left in the emulsion to form a masking image in each case. If the coupler in the blue-sensitive layer couples to give a magenta image, it is preferred to use a coupler in the green-sensitive layer which is orange in its uncoupled state and couples to give a cyan image, while if the coupler in the blue-sensitive layer couples to give a cyan image, the coupler in the redsensitive layer is preferably yellow in its uncoupled state and couples to give a magenta image. Suitable yellow colour couplers which produce a magenta dye image are 1-(p-tert.- butylphenoxy) - phenyl - 3 - α - (p - tert. - butyl - phenoxy)-propionylamino-4-y-methoxyphenylazo-5-pyrazolone and 1-(p-tert.-butylphenoxy)- phenyl - 3 - α - (p - tert. - butylphenoxy) - propionyl - amino-4-o-toluene-azo-5-pyrazolone. Either of these may be mixed with an uncoloured magenta coupler such as 1 - (p - tert. - butylphenoxy) - phenyl - 3 - α - (p - tert. - butylphenoxy) - propionylamino-5-pyrazolone to give the required degree of correction. Suitable coloured couplers for producing a cyan image are 41-(ptert. -butylphenoxy) - 1 - hydroxy - 4 - phenylazo - 2 - naphthanilide (orange-yellow) and 1-hydroxy-4- (2<SP>1</SP>-methoxy - 4<SP>1</SP>- nitrophenylazo) - 2 - (4<SP>11</SP>-sec.- amylphenyl) naphthamide (red, and therefore not suitable for use in the blue-sensitive layer). Such couplers are described in Specifications 586,211, 598,174, 598,657 and 627,814. They may be mixed with other couplers such as 1 - hydroxy - 2 - [α - (2: 4 - di - tert.-amylphenoxy - n - butyl]-naphthamide and 2-(2<SP>1</SP>: 4<SP>1</SP>-di-tert.-amylphenoxyacetamino) - 4 : 6 - dichloro - 5 - methyl phenol to give the required amount of correction as described in Specification 617,247. A suitable coupler which produces a yellow dye image is N-(4-benzoylacetaminobenzenesulphonyl)-N- (γ - phenylpropyl) - p - toluidine. The colour materials of the invention are useful in a 3-stage process for making colour pictures, particularly colour motion pictures, wherein an original material is exposed in the camera, printed on to an internegative and the final print made from the internegative. The original or internegative material may be a false-sensitized material according to the invention, but the print material cannot, since as it is to be used for viewing it must not contain a masking image. Two such processes are described, in the first the original is a material according to the invention wherein the blue-sensitive layer contains a yellow colour coupler giving a magenta dye image, the green-sensitive layer contains an orange coupler giving a cyan dye image and the red-sensitive layer contains a colourless coupler which gives a yellow dye image. When exposed to a coloured subject and colour developed to either a positive or a negative, the three primary colours of the subject (the " image aspects ") will be blue, green and red in that order, from the top corresponding to the sensitivities of the layers, but the images will be " false-colour," i.e. the image record will be of a colour other than that which is complementary to its image aspect. In the example given, the original material is colour developed to a positive in the usual way. Various combinations of internegative and print material are given for use with this original, and in each case the print material will have natural-colour, but it may be falsesensitized or natural-sensitized depending on whether the internegative is false- or naturalcolour. Some of the internegatives are materials according to the invention. The original positive is printed on to the internegative in each case and these are then colour developed to negatives. The internegatives are then printed on to the appropriate print material to give a natural colour record. In the second method described, the original material is natural-sensitized, natural-colour and, after exposure is developed to a negative. Separation positives are then made in the usual way using blue, green and red filters and these are printed in turn on to an internegative according to the invention wherein the blue, green and red sensitive layers couple to give magenta, cyan and yellow images and the magenta coupler is coloured yellow in its uncoupled state. The blue filter positive is printed through a red filter to give the blue image aspect in the bottom layer, the green filter positive is printed through a blue filter to give the green image aspect in the top layer and the red filter positive is printed through a green filter to give the red image aspect in the middle layer. The internegative is then colour developed to a negative and printed directly on to the print material. The latter is natural-sensitized natural colour but has sensitivities of the layers in the order green, red and blue from top to bottom, and it is colour developed to a positive followed by silver-bleaching and fixing. In a specific example of a material according to the invention the red-sensitive layer contains the coupler N - (4 - benzoylacetaminobenzenesulphonyl) - N - (γ-phenylpropyl)-p-toluidine which gives a yellow dye image, the green-sensitive layer contains the orange-yellow coupler 4<SP>1</SP>-(p-tert.- butylphenoxy) - 1 - hydroxy - 4 - phenylazo - 2 - naphthanilide which gives a cyan dye image and the blue-sensitive layer contains the yellow coupler 1-(p-tert.-butylphenoxy) -phenyl-3-α-(ptert. - butylphenoxy) - propionylamino - 4 - o - toluene azo-5-pyrazolone which gives a magenta dye image. The couplers in the red- and greensensitive layers are dispersed in dioctyl hydroquinone and dibutyl phthalate and each layer is coated with a further dispersion of these two compounds in gelatin before the next layer is coated. The blue-sensitive layer contains trio-cresylphosphate, tartrazine and fluorescin. It is used as the original material in the first method described above. Specifications 475,784, 475,786, 541,589 and 599,377 also are referred to.