Patent GB-461559-A (GB)
Title: Improved light-sensitive material for colour photography
IPC: G03C1/76
Filed: 1935-07-13
Abstract: 461,559. Colour photography. GROVES, W. W. (I. G. Farbenindustrie Akt.-Ges.) July 13, 1935, No. 20100. [Class 98 (ii)] The emulsion layers of multilayer sensitive material are separated one from another by an intermediate layer impermeable to the liquids used for treating an emulsion layer above it, but which may be treated to render it permeable to the liquids used for treating an emulsion layer below it. The intermediate layer may contain an impermeabilizing agent such as a cellulose derivative, which may be partially saponified, e.g. acetyl cellulose, and an adhesive agent such as gelatin ; and the layer may be rendered permeable by the action of an alcoholic caustic potash solution. Or the impermeabilizing constituent may be one which is insoluble in acid or neutral treating solutions, but soluble in alkaline solutions (or vice versa), so that the second-mentioned solution renders the layer porous and permeable. Two examples of such layers are given in the Specification. The invention includes the use of such material in the silver bleach - out dye process described for example in Specification 133,034, [Class 98 (ii)]. In one example, a film bears on one side a green-sensitive emulsion, and on the other side a red-sensitive emulsion separated from an over-coated ordinary emulsion by a layer of the character above described, the red-sensitive layer or the separating layer being coloured yellow to serve as a filter. After exposure from the side carrying two emulsions, development is restricted to the external emulsion layers, and the images formed therein may be converted to dye as by dyeing uniformly with yellow and purple dyes and destroying the dye at the silver deposits by the silver bleach-out dye method. Treatment with alcoholic caustic potash then renders the separating layer permeable, whereafter the third emulsion layer may be developed and coloured blue-green as by reversal followed by toning. Alternatively, the layers may contain dye components which are subsequently coupled to form dyes by reagents which may be included in the developers, dye-image formation proceeding thereafter by the silver bleach-out dye method. In a second example, a similar film is used having on one side an emulsion sensitized for light which is not blue (e.g. green) and containing a yellow filter dye, separated by an impermeable layer from an over-coated emulsion sensitive to blue, and on the other side an emulsion sensitive to blue. Either of the blue-sensitive emulsions may be sensitized complementarily to the firstmentioned emulsion, e.g. to red. Partial colour records are copied on the film, using in each case a printing light of a colour to which the corresponding print layer is sensitive, as described in Specification 375,338 ; the two outer layers are developed separately with colour-forming developers ; the separating layer is rendered permeable as before ; and the third layer is then developed to colour. A modification of the second example is described wherein the components are printed from records made on the pack described in Specification 395,124, the two records on the front lenticular film of the pack being printed with appropriate coloured lights in the two layers on one side of the copy material, and the record on the rear smooth film of the pack being printed on the single layer side.