GB1269805A - Photographic silver halide products and diffusion transfer processes - Google Patents

Abstract

1,269,805. Photographic silver halide products and diffusion transfer processes. POLAROID CORP. May 13, 1969 [May 13, 1968; April 14, 1969], No.24292/69. Heading G2C. A process of forming by diffusion transfer a composite print comprising a colour positive image that is viewable by reflected light and that is over a negative image, comprises exposing a laminate comprising a dimensionally stable transparent support that carries layers that are permeable to aqueous alkaline processing composition, the layers comprising a photo-sensitive silver halide layer having associated therewith a compound providing, as a function of development, an imagewise distribution of dye image-forming material, an image-receiving layer dyeable by the image-forming material, and an opaque layer between the silver halide and image-receiving layers, developing the silver halide by applying aqueous alkaline processing composition over the surface of the laminate distant from the support, at least a portion of the resultant imagewise distribution of dye image-forming material transferring by diffusion to the image-receiving layer, a dye image being formed therein in terms of the imagewise distribution, and maintaining the laminate intact subsequent to processing. Integral with the laminate there is preferably an aqueous alkaline processing composition and means for applying the composition as a uniform layer over the surface of the laminate distant from the support. The means for applying the composition may comprise a transparent or opaque cover sheet superposed the laminate or attached to the laminate and being capable of superposition. The processing composition, which may contain an opacifying agent, may be in a rupturable container which is positioned to discharge its contents upon rupture between the laminate and the cover sheet when the later is superposed. Between the transparent support and the adjacent imagereceiving or silver halide layer there is preferably a polymeric acid (neutralizing) layer which may be separated from the adjacent image-receiving or silver halide layer by a spacer layer. The compound providing the dye image-forming material may be a dye-developer. More than one selectively sensitized silver halide emulsion layer and its associated compound may be present and these layers may be separated by a polymeric interlayer that is permeable to the aqueous alkaline processing composition. The opaque layer preferably comprises a layer of actinic radiation reflective material, preferably titanium dioxide with a reflectance above 85%. The opaque layer, in a stratum of the layer distant from the imagereceiving layer may contain an actinic radiation absorptive material, preferably carbon black.