GB507418A - Photographic multilayer material for colour photographic purposes - Google Patents

Abstract

507,418. Colour photography. CASPAR, B. Dec. 9, 1937, No. 34083. [Class 98 (ii)] Multi-layer material comprises at least one sensitive layer which is coloured with a dyestuff which transmits the light to which the layer is sensitized and absorbs the light to which the layer above it is sensitive and which is capable of being bleached by the silver image, the layer containing an additional dyestuff of the same colour which is, however, totally removed by the treating solutions which are harmless to the image-forming dye. In an alternative, the additional dyestuff is one of similar properties to the image-forming dyestuff and is destroyed in the presence of finely divided silver. The concentration of the first dye is sufficient for colouring the most intensely coloured parts of the image, whilst the concentrations of both dyes are together sufficient to absorb all the light to which the front layer is sensitive. The auxiliary dyestuff may be in a separate colloid layer. In one example, a green or red sensitized emulsion dyed by a mixture of Xylenewalkgelb and 4 : 4<1>-methenylbis-[1-(p-sulpho-phenyl)-3-methyl-pyrazolone-5] is arranged between a blue sensitive silver halide emulsion layer dyed magenta with a salt of Tuchechtbrillantrot and a blue sensitive silver halide layer dyed blue - green with Pontamine Sky Blue 5BX. The,support may be adjacent one of the outer layers or between the layers. The dyestuff is decolourized by an alkaline developer or by sulphite or bisulphite compounds, and the dyestuff images are produced as in Specification 415,040. In a second example, a support is coated with a silver halide layer coloured blue-green with a quinolinium salt of Pontamine Sky Blue 5BX and sensitized with Cryptocyanine for infrared light, and containing also a destructible dyestuff obtained from 1-(p-sulphophenyl)-3- methyl-pyrazolone-5 and glutaconic-dialdehydedianilide. The destructible dyestuff may be in a separate thin gelatine layer. An emulsion layer sensitized to rod with pinacyanol and coloured magenta with a quinolinium salt of Tuchechtbrillantrot 2B is coated directly on the blue-green layers. The magenta layer or a separate layer lying above it contains a red dyestuff which may be the diphenyl guanidine salt of the sulphonic acid of methenyl-bisoxythionaphthene. A yellow coloured layer sensitized to green is coated above this layer. The auxiliary layers may be light-sensitive and the dyestuffs therein destroyed after a diffuse illumination which allows a separate exposure of the auxiliary layers. Specifications 408,991 and 506,385 are referred to.