Patent GB-804976-A (GB)
Title: Improvements relating to color photography
Inventor: ROGERS HOWARD GARDNER
IPC: C09B1/20
Filed: 1955-03-09
Abstract: 804,976. Photosensitive element for multicolour diffusion-transfer procedure. INTERNATIONAL POLAROID CORPORATION. March 9, 1955, No. 38804/57. Divided out of 804,972. Class 98(2) A multiplicity of silver halide elemental portions containing chromogenic reagents and/or dyes and normally exposable at different wavelengths are arranged on a support in side by side relation in colour screen pattern to produce, after exposure and development, non-diffusible images in exposed areas and dye images in a printreceiving material by transfer of the chromogenic reagents and/or dyes from unexposed areas, to yield colour preferably complementary to the colour of the wavelength range of the silver halide portion from which diffusion is effected. A container of processing liquid may be adhered to the surface of the photosensitive element or to the receiving material to enable image production by passage through pressure rolls. The invention is first detailed at some length as used with ordinary colour formers, thus in Fig. 2, in which the overlying emulsion strips may be spaced at about 250 lines per inch, the emulsions are made up by melting the colour developer 2 - amino - 5 - diethylaminotoluene hydrochloride and triphenyl phosphate with a little aqueous sodium hydroxide, adding coupler to the melts using 2.4 - dichloro -1 - naphthol, p - nitrophenylacetonitrile, and acetoacet - 2 - chloranilide or - 2. 5 - dichloranilide for red (25), green (26), and blue (27) sensitive portions respectively; emulsifying the resultant melts into aqueous gelatin, and adding the products to silver halide emulsions of such sensitivities containing filter dyes where necessary to restrict exposure to the portions concerned. The triphenyl phosphate is used to avoid wandering of coupler and other refinements, such as the provision of insulating layers of ntrooellulose beneath, the upper emulsion portions to produce correct operation are described. The material of Fig. 2 may be calendered after production to locate the outer faces of the elemental portions in the same plane or an, embossing and inlaying sequence may be used to produce a similar result. Instead of the elemental portions containing a mixture of the image-forming reagents they may comprise individual strata thereof, or suitable reagents may be screenwise applied to an already formed silver halide layer. After exposure of the material of Fig. 2, processing may be effected in the " hand " manner as shown in Fig. 5, with aqueous alkaline carboxymethyl cellulose in the fracturable container and an oxidizing agent, preferably copper sulphate or this with potassium cyanate in the image-receiving layer, to .produce dye from coupler transferred thereto from non-image emulsion portions. Aerial oxidation may be used instead of oxidizing agent. In other concepts of the invention, complete dyes with a coupling function may be used in the emulsions, allowing transfer of the portions not retained by the coupling reaction, such dyes are listed with reference to the Index of the Society of Dyers and Colourists, and benzene sulphonyl hydrazide type of developers may be used therewith; stabilized diazonium salts may form dye with unreacted coupler, or indicator dyes may be used in the transfer. Specifications 684,591, 684,592, 685,685 and 706,921 are referred to.