GB529033A - Improvements in and relating to the manufacture of photographic light-sensitive elements - Google Patents

Abstract

529,033. Photographic composite coloursensitive materials. KODAK, Ltd. (Eastman Kodak Co.). March 9, 1939, No. 7640. [Class 98 (ii)] Diffusion of a colour sensitizer from one light sensitive emulsion to another coated on the same side of a support is prevented or retarded either (1) by adding to the second-mentioned emulsion, or to an interlayer between the two emulsions, a soluble salt e.g. of an alkali metal, which is inert photographically and towards the light sensitive silver salt, and which forms a difficultly-soluble salt of the sensitizing dye, but does not form a very difficultly-soluble or undissociated salt with silver ; or (2) when the second-mentioned emulsion is not specially colour-sensitized, by adding to this emulsion a dye of a sensitizing class so chosen that it does not substantially alter the colour sensitivity of the emulsion. The emulsion may be of gelatino-silver halide, in superimposed layers or admixed in one layer. The salt used according to method (1) may be an alkali salt of one of the highest oxyacids of the halogens, e.g. a perchlorate or periodate. For silver bromide or bromiodide emulsions, the dye used according to method (2) may be one which sensitizes silver chloride emulsions for blue and violet, and examples are given in which the green-sensitizing dye 2 : 21-diethyl-3 : 4- benzthia - 2<SP>1</SP> - cyanine iodine is prevented from wandering into a neighbouring not specially colour-sensitized emulsion by dyeing this emulsion with 2 : 2<SP>1</SP>- diethyl : 5 : 6 : 5<SP>1</SP> ; 61- dibenzthiacyanine iodide, or 2 : 21-diethyl-3 : 4 : 3<SP>1</SP> : 4<SP>1</SP>-dibenzthiacyanine iodide, or 5-(1-methyl- 2-# naphthoxazylidene)-3-ethylrhodanine, or 1- (#-(1-piperidyl) - vinyl) - benzthiazole ethiodide. Specification 500,826 is referred to.