GB670457A - Improvements in colour photographic materials - Google Patents

Abstract

670,457. Colour photography. KODAK, Ltd. Sept. 2, 1949 [Sept. 3, 1948], No. 22840/49. Class 98 (ii). A light-sensitive layer comprises a watersoluble water permeable colloidal binder such as gelatin having dispersed therein particles of y-phenylpropyl alcohol containing silver halide peptized with a water-insoluble material such as zein and also containing a colour coupler. The layer may contain two or more sets of such particle-emulsions differently colour sensitive, and may comprise a redsensitized silver chloride emulsion containing a cyan colour coupler, a green sensitized silver chloride emulsion containing a magenta colour coupler and a blue-sensitive silver bromide emulsion containing a yellow colour coupler. The layer is made, preferably, by a process following that of Specification 670,458, in which silver halide forming reagents are dispersed in a solution of zein in an aqueous lower aliphatic alcohol, and the result is washed and dispersed in benzyl alcohol; at this point coupler and sensitizing dye separately dissolved in y-phenyl propyl alcohol are stirred into the dispersion and the product further dispersed in gelatin solution; which final mixture is set, shredded, washed, melted and coated to form a layer. Similar dispersions using different sensitizers and couplers may be mixed to form a two-colour or three-colour layer, and such layers may be exposed and colour developed, as with a colour developer of pH of at least 10.5 to provide a coloured image. Example 1 describes production of a mixed green and red sensitive silver bromide positive type emulsion layer using 3 - ethyl - 5 - [(3) - ethyl - 2 - (3) - benzoxazolylidene) - isopropylidene] - rhodanine as sensitizer and I-phenyl-3-pentadecyl-5-pyrazolone as magenta coupler for the green-sensitive particles and 3-ethyl-5-[(l-ethyl-2-(l)-[3-naphthothiazolylidene) - α - ethylethylidene] - 2 - (3- # - hydroxy - # - ethoxy - # - ethoxyethyl - 4- oxo - 2 - thiono - 5 - thiazolidylidene) - 4 - thiazolidene as sensitizer and 2-lauryl-4-chlorophenol as cyan coupler for the red-sensitive particles, exposure of this through red and green filters and colour development to produce cyan and magenta images in portions exposed to red and green light, respectively. Such a layer may be overcoated with a single emulsion layer containing a yellow coupler and provided with a yellow filter dye to produce a three-coloured image. Example 2 describes production, exposure and treatment of the single mixed grain layer using chloride emulsions which are insensitive to blue for the red and green particles and a bromide emulsion for the blue particles as referred to above.