GB1393462A - Photographic silver halide products and diffusion transfer processes - Google Patents

Abstract

1393462 Photographic diffusion transfer material containing particulate developer complex POLAROID CORP 18 April 1972 [19 April 1971] 17888/72 Heading G2C A photographic diffusion transfer film unit comprises a photo-sensitive silver halide layer having associated therewith a dye-developer which is diffusible during processing as a function of imagewise exposure and an image-receiving layer, at least one layer in the film unit comprising a particulate dispersion of a complex of a synthetic polymer with a silver halide developing agent which is dissociable as a function of pH. The synthetic polymer may be wholly synthetic or a synthetically modified naturally occuring polymer. The complex may be a H- bond complex of the synthetic polymer with a benzenoid silver halide developing agent having at least two groups selected from amino and OH, at least one of the groups being substituted in the ortho or para position with respect to another of the groups e.g. a complex of polyvinylpyrrolidone and 4-methylphenyl-hydroquinone which may be present in the green-and blue-sensitive silver halide emulsion layers. Numerous suitable synthetic polymers and developing agents are listed. The complex particles may have a mean particle size not in excess of 1 micron. The complex is preferably water-insoluble and dissociates upon contact with aqueous alkaline processing composition. The film unit may contain an opacifying agent, a rupturable container retaining aqueous alkaline processing composition and an alkali-neutralising layer. The tendency of the auxiliary developing agent to fog silver halide in the film unit is reduced.