Patent GB-1330524-A (GB)
Title: Photographic assemblage for producing a colour image
IPC: G03C8/12
Filed: 1970-10-23
Abstract: 1330524 Photo-sensitive dye diffusion transfer material EASTMAN KODAK CO 23 Oct 1970 [24 Oct 1969 (2) 13 April 1970 (2)] 50535/70 Heading G2C A photo-sensitive element comprises a transparent support and superposed thereon in the following order: a dye image-receiving layer, an opaque, light-reflecting layer or layers which are permeable to alkaline aqeuous processing liquid and one or more photo-sensitive silver halide emulsion layers each of which contains, or is adjacent to a layer containing, a dye imageproviding material which is non-diffusible in the presence of said alkaline processing liquid and which produces a dye which is diffusible in said liquid as a result of reaction with oxidized silver halide developing agent. A photographic assemblage may comprise (a) the above photo-sensitive element, (b) a reservoir of said alkaline aqueous processing liquid, the reservoir being capable of releasing said liquid when subjected to pressure, (c) a process sheet of a size sufficient to cover at least the image area of the upper surface of the photosensitive element and (d) opacifying means capable of forming an opaque covering over the image area of the upper surface of the photo-sensitive element, a silver halide developing agent being present in (a) or (b) and said reservoir being located in the assemblage so that the liquid is released between the upper surface of the photosensitive element and the process sheet when superposed on the upper surface over the image area. The dye-image providing material may comprise a non-diffusible coupler and the developing agent may be an aromatic primary amino colour developing agent. The process sheet (c) and the opacifying means (d) may be combined as an opaque process sheet which is superposed over the uppermost layer of the photo-sensitive element (a) after exposure thereof. Alternatively the process sheet (c) may be transparent and be superposed on the uppermost layer of the photosensitive element (a) and the opacifying means (d) may be dispersed in the alkaline processing liquid. The assemblage may comprise a developer scavenger layer in the photo-sensitive element (a) between the dye image-receiving layer and the nearest silver halide emulsion layer, its scavenging function being delayed until development is substantially complete. The developer scavenger layer may comprise a non- diffusible coupler capable of reacting with oxidized aromatic primary amino colour developing agent to form a non-diffusible product and a silver halide emulsion that is developable without exposure. The assemblage may comprise a pH lowering layer or layers that are capable of lowering the pH of the assemblage after formation of the dye image in the receiving layer from pH 14 to pH 11 or lower. The opaque lightreflecting layer may comprise a white lightreflecting layer behind the dye image-receiving layer (looked at from the support) and an opaque layer permeable to the processing liquid behind the white light-reflecting layer. The silver halide emulsion layer(s) may be direct-positive and may be internal image emulsion layers. Each dye image-forming unit of the assemblage may comprise in order from the support (i) a developable emulsion layer of a hydrophilic colloid and a water-insoluble metal salt and containing physical development nuclei, the emulsion layer being developable by the developing agent without exposure to light and the metal salt having contiguous thereto the non-diffusible coupler for producing the diffusible dye, and (ii) a silver halide emulsion layer sensitive to a particular part of the spectrum, the silver halide having contiguous thereto a non-diffusible DIR (development inhibitor-releasing) coupler which is capable of reacting with oxidized aromatic primary amino colour developing agent to release a diffusible mercaptan development inhibitor which is capable of diffusing imagewise to layer (i) to inhibit development therein, and between adjacent dye image-forming units there may be a hydrophilic colloid layer permeable to the processing liquid which contains a water-insoluble substance that reacts with the diffusible mercaptan to form an insoluble salt between adjacent dye image-forming units. Alternatively, each dye image-forming unit of the assemblage may comprise in order from the support (i) a layer containing physical development nuclei and the non- diffusible coupler for producing the diffusible dye, (ii) a spacer layer and (iii) a silver halide emulsion layer sensitive to a particular part of the spectrum and containing an immobilizing coupler that is capable of reacting with oxidized aromatic primary amino silver halide developing agent to form a non-diffusible product and between adjacent dye image-forming units there may be a barrier layer which retains soluble silver ion complexes between adjacent units, a silver halide solvent being present in the assemblage in a layer of the photo-sensitive element or on the process sheet or in the processing liquid. The processing liquid may be inserted into the film unit using e.g. a hypodermic syringe which is attached to the camera or camera cartridge. The assemblages can be exposed and processed in a camera having a conventional optical system to give a visible night-reading colour print without requiring peeling off of the dye image and can be withdrawn from the camera before processing is complete.