GB1446227A - Photographic silver halide materials and processes - Google Patents

Abstract

1446227 Photographic silver halide material EASTMAN KODAK CO 20 Nov 1973 [20 Nov 1972] 53721/73 Heading G2C A photographic material comprises a support bearing at least two dye image-providing units comprising respectively (i) a silver halide emulsion layer having contained therein or in an adjacent layer a first colour coupler and (ii) a silver halide emulsion layer having a mean silver halide grain size at least 50% larger than that of the emulsion layer in unit (i) and having contained therein or in an adjacent layer a second colour coupler, (ii) also containing a black-and-white silver halide developing agent at at least 0À1 mg/ft<SP>2</SP> of support. The couplers may be dispersed as droplets of a waterinsoluble coupler solvent or solvent mixture. The second coupler may be a yellow coupler. (ii) may be nearer the support than any other emulsion layer. The black-and-white developing agent is optionally present at 0À1-200 mg/ft<SP>2</SP> of support, and is preferably a 3-pyrazolidone. (ii) may have a mean grain size of at least 0À8 micron. The dye image-providing units may be separated by interlayers. Unit(s) (i) may contain the silver halide emulsion at less than 30 mg/ft<SP>2</SP> based on silver. The coupler in unit(s) (i) may be present at at least 40% stoichiometric excess based on the developable silver in its associated emulsion layer. The material may be treated with a solution containing a cobalt (III) ion complex during or after the treatment with a colour developer solution (see Ex 1 and 2). The exposed and colour developed material may be treated with a solution containing a peroxy compound so that amplification of the dye image occurs (see Ex 3). The couplers may form diffusible or non-diffusible dyes. The incorporation of the black-and-white developing agent increases the rate of colour development, probably by shortening the normal induction period prior to development proper.