GB490517A - Production of black-and-white photographic pictures - Google Patents

Abstract

490,517. Photographic processes. GROVES, W. W. (I. G. Farbenindustrie Akt.- Ges.) Dec. 11, 1936, No. 34052. [Class 98 (ii)] Photographic silver-free black-and-white pictures are obtained by the use of a silver halide emulsion layer containing a dyestuff component which is converted into a black dyestuff and which is fast to diffusion in the binding medium of the emulsion, for example, N-dodecyl-1- : 2-hydroxynaphthoyl-2<1>-aminocarbazole, mdodecoylaminophenylhydroxynaphthothiazolesulphonic acid and 4 - (alphahydroxynaphthoyl) - 4<1> - (p - nitrobenzoylacetyl )- di-chlorobenzidide. The silver is removed after the production of the dyestuff picture by a suitable solvent, such as Farmer's reducer. The dyestuff picture may be produced by simple or reversal colour development using a developer such as p-diethylaminoaniline, by azo-coupling as described in Specification 436,587, or by destroying the dyestuff component or the dyestuff produced therefrom directly or indirectly by way of the silver image. The dyestuff components may comprise a coupling group linked to a polynuclear group, or may be formed by linking components individually forming different colours, for example, blue, green, and red, or blue and yellow, on colour development. The components may be linked by linking carboxyl, amino, hydroxy, or sulpho groups to yield acid amides or esters. The components may be rendered fast to diffusion, as described in Specifications 436,587, 458,400, 465,823, 479,838, 483,000, 484,698, 489,093, 489,161, and 489,274. Substituents such as nitro-groups or halogens may be introduced into the components to increase the depth of black of the resulting dyestuffs, and in colour development colour developers containing such substituents may be used. The dyestuff produced may be converted into a darker dyestuff by diazotization and coupling with azocoupling components or by the action of diazocomponents on such dyestuffs. The process may be applied to the production of sound films. A mixture of several dyestuff components may be used. The components may be in several layers arranged on one or both sides of the support. Specifications 468,946, 481,501, and 488,853 also are referred to. The Provisional Specification refers also to the addition of the components to the developer.