Patent GB-1456413-A (GB)
Title: Diffusion transfer colour photographic silver halide film unit
IPC: G03C8/00
Filed: 1974-05-31
Abstract: 1456413 Photographic dye diffusion transfer silver halide film unit FUJI PHOTO FILM CO Ltd 31 May 1974 [31 May 1973] 24336/74 Heading G2C A photographic dye diffusion transfer film unit adapted to be processed by spreading processing composition between a light-sensitive element and an image-receiving element comprises (1) a lightsensitive element having a transparent support coated on one side thereof with blue-green- and redlight sensitive negative silver halide emulsion layers containing non-diffusible yellow, magenta and cyan dye-forming ballasted couplers respectively, and adjacent each of these layers corresponding lightinsensitive layers containing diffusible yellow, magenta and cyan dye-forming ballasted and colourless couplers respectively, the diffusible dyes being released upon development of the lightsensitive layers in an imagewise distribution from the light-insensitive layers by the action of an image distribution-transmitting agent (i.e. a compound capable of migrating to a light-insensitive layer from a light-sensitive silver halide emulsion layer and reacting to form a positive image corresponding to the negative image in the light-sensitive layer) imagewise released as a result of the development of the light-sensitive emulsion layers, (2) an imagereceiving element comprising a support bearing an image-receiving layer and (3) a rupturable container containing an alkaline processing composition, the film unit containing an aromatic primary amine colour developing agent in the processing composition, or an aromatic primary amine colour developing agent precursor in the light-sensitive element, which precursor provides the developing agent on hydrolysis by the processing composition. The image distribution-transmitting agent may be a development inhibitor released from at least one light-sensitive layer in a negative imagewise distribution by reaction of a compound in at least one light-sensitive layer with oxidized aromatic primary amine colour developing agent, and at least one of the light-insensitive layers may be spontaneously developable. The image distribution-transmitting agent may be a water-soluble silver complex released in an imagewise distribution from at least one light-sensitive layer by dissolving undeveloped silver halide grains therefrom with a silver halide solvent. At least one of the light-insensitive layers may contain development nuclei. The film unit may have at least one light-intercepting layer, containing e.g. black colloidal silver, which protects the light-sensitive layer from external light during processing, and which may be coated on the light-sensitive, elements transparent support opposite its coated side. The light-intercepting layer may be easily removable (see Examples) and be permeable to the processing composition. The film unit may also contain a light-intercepting element having an opening to receive the exposed light-sensitive element and being bonded to the  image-receiving element at the margins with the image-receiving layer towards the exposed lightsensitive element. The processing composition may be put into the rupturable container in atmosphere of gaseous dichlorodifluoromethane (see Examples) and may contain a light-absorbent so that on spreading the composition the light-intercepting  layer is formed in situ. The film unit may contain a light-reflecting substance to mask the lightintercepting layer and to form a white background for the transferred dye images. The light-reflecting substance may be in the processing composition, a processing composition permeable layer between the image-receiving layer and light sensitive element during processing, in the image-receiving elements support, or between the image-receiving layer and its support. The film unit may contain a delaminating layer between the light-sensitive and imagereceiving elements. In the Examples the lightsensitive layers contain sensitizing dyes. A colour negative image maybe obtained on bleaching and fixing the light-sensitive element (see Examples) and a colour positive obtained in the imagereceiving layer.