Conventional Wet Silver Halide Processes
In conventional aqueous processing of silver halide based color photographic elements, an imagewise exposed element, for example color paper designed to provide color prints, is processed in a large volume of color developer solution. The element is typically immersed in a deep tank of aqueous processing solution wherein the volume of solution is much greater than the volume of the element therein immersed and wherein the volume of solution is much greater than the swollen volume of the light sensitive emulsion layers coated upon the photographic element. The developer typically reduces the exposed silver halide of the element to metallic silver and the resulting oxidized color developer reacts with incorporated dye-forming couplers to yield dye images corresponding to the imagewise exposure. Since silver is generally gray and desaturates the pure colors of the dyes, it is desirable to remove it from the dye images. Silver is conventionally separated from the dye images by a process of bleaching the silver to a silver halide and removing the silver halide by using a fixing bath. This fixing bath also removes the undeveloped silver halide. Commonly, the bleach and fix are combined into one solution, a bleach-fix solution.
Color Diffusion Transfer Systems
Diffusion transfer processes in photography are well known. Cieciuch et at., in U.S. Pat. Nos. 3,719,489 and 4,060,417, describe photographic processes employing certain compounds which are stable in photographic processing composition but capable of undergoing cleavage in the presence of an imagewise distribution of silver ions created during processing of a silver halide emulsion to liberate a photographically active reagent or a dye in an imagewise distribution corresponding to that of said silver ions. Depending on the photographic process and the result it is desired to achieve the inert parent compound may be diffusible or substantially nondiffusible in the processing solution and the reagent liberated also may be diffusible or substantially nondiffusible in the processing composition.
Land, in U.S. Pat. No. 3,615,421, Taylor, in U.S. Pat. No. 4,202,694, and Murphy, in U.S. Pat. No. 4,680,247, disclose laminated multilayer diffusion transfer film units that comprise two supports (forming the outer surfaces of the respective units). One of said supports is a transparent support (through which the final color dye image is observed, and the other of said supports is usually an opaque support or a transparent support with an adjacent opaque layer. Processing fluids in such film units are dispersed from rupturable pods between various layers inside said units.
Pfingston, in U.S. Pat. No. 4,401,746, discloses a diffusion transfer element comprising in order a topcoat protective layer, light-sensitive and dye providing layers, a stripping layer, a dyeable stratum, and a support. The processing composition may be applied to the exposed photosensitive element by dipping. The developing agent may be any of those commonly employed. The dyeable stratum together with any other image-receiving components are separable from the photosensitive component using the stripping layer.
Boie et al., in U.S. Pat. No. 4,429,033, disclose a process for color print production by diffusion transfer, wherein the diffusion transfer element comprises, in order, a transparent layer support, a light-sensitive element comprising silver halide and a non-diffusing color-providing compound, a light-reflecting opaque layer, and a mordant layer. After development, silver and silver halide are removed by bleaching and fixing.
Boie et al., in U.S. Pat. No. 4,508,809, disclose a process and apparatus for exposing and developing photographic images in a diffusion transfer elements. Said element comprises a monosheet material containing a layer which is impermeable to light but permeable to moisture. Said layer divides said element into a photosensitive side for image-wise exposure and a non-photosensitive side for observation and supplying of activator or developer solution. The photosensitive side of said element is exposed image-wise in the dark and then sealed in said apparatus in a light-proof manner, whereby the non-photosensitive side of the element lies open and is exposed to an activator to develop the image. Said exposure to activator may be done in daylight, and once the image quality has been achieved, development is stopped by removal of activator, rinsing, and drying the element in the conventional manner.
Finn and DeBoer, in U.S. Pat. No. 4,485,165, disclose diffusion transfer elements for producing monochromatic dye images comprising (1) a support having thereon a layer of nondiffusible dye image-providing material, a stripping layer, an opaque layer, and a silver halide emulsion layer; (2) a transparent cover sheet; and (3) an opaque processing composition for application between the element and cover sheet. A dye mordant layer may also be present on the element or cover sheet. After exposure and processing, the layer of nondiffusible dye image-providing material on a support is snipped away to provide a monochromatic retained dye image without the need for bleaching and fixing.
Karino, in U.S. Pat. No. 5,112,720, discloses a color diffusion transfer film unit comprising (1) a support having a light-shielding function in itself and/or having thereon a layer having a light-shielding function; (2) a light sensitive element on the support comprising, in order from the support at least (a) a color image receiving layer, (b) a peeling layer, and (c) at least one silver halide emulsion layer associated with a color image-forming substance; (3) a light-shielding agent containing alkali processing composition; and (4) a cover sheet comprising at least a layer having a neutralizing function on a transparent support, wherein said cover sheet is characterized by having a dye-trapping layer comprising a mordant in a binder adjacent to the alkali processing composition.