GB1389569A - Direct-positive multi-layer light-sensitive silver halide material - Google Patents

Abstract

1389569 Photographic direct-positive silver halide material FUJI PHOTO FILM CO Ltd 20 April 1972 [20 April 1971] 18467/72 Heading G2C A direct-positive light-sensitive silver halide material comprises a support having on the same side thereof at least two emulsion layers which may be of the same or different type selected from (A) a chemically surface fogged direct-positive light-sensitive silver halide emulsion layer in which at least one sensitizing dye (term defined in Specification) and/or electron acceptor (i.e. a material which is capable of trapping free electrons which are generated in the silver halide grains by irradiation with photons) is adsorbed on the silver halide grains, said grains having free electrontrapping nuclei therein, (B) a chemically surfacefogged light-sensitive silver halide emulsion layer rendered direct-positive by the presence of at least one electron acceptor adsorbed on the silver halide grains, said grains being free from free electron-trapping nuclei and free from positive hole-trapping nuclei and (C) a chemically surfacefogged direct-positive light-sensitive silver halide emulsion layer in which at least one electron acceptor is adsorbed on the silver halide grains, said grains having free electron-trapping nuclei therein but being free from positive hole-trapping nuclei therein, said material having between each pair of adjacent emulsion layers an intermediate layer capable of preventing diffusion or interaction between the emulsion layers. If two adjacent emulsion layers are of the same type they preferably differ in direct reversal sensitivity. The emulsion layers and intermediate layers may be applied by simultaneous multi-layer coating. The material may comprise blue-, green- and redsensitive silver halide emulsion layers containing yellow, magenta and cyan couplers respectively. The formulae of many electron acceptors and sensitizing dyes are given in Fig. 26 (not shown). The intermediate layer may comprise an emulsion layer containing a negative type silver halide, or silica each having a grain size less than 0À2 micron and each being present at e.g. less than 75g per 100g dry gelatine to prevent diffusion of the electron acceptor or sensitizing dye. The intermediate layer may contain a cationic or anionic hydrophilic polymer or an anionic surfactant to prevent diffusion of the electron acceptor or sensitizing dye. The intermediate layer may contain a masking colour coupler or a dye.