Improvements in and relating to photographic colour developers and photographic colour development

摘要

615,218. Photographic colour development. GEVAERT PHOTO-PRODUCTEN N. V. Dec. 11, 1945, No. 33443. Convention date, March 17,1941. [Class 98 (ii)] A reducible silver salt image is colour developed with an aromatic amino developing agent in presence of a colour coupler of the formula (CN-CH2-CO-NH-N = )nX, wherein n is 1 or 2 and X is any organic residue containing no reactive methylene group and capable of forming a hydrazone by reaction with a hydrazine. The coupler may be in the developer or a silver halide emulsion layer. The usual aromatic amino developing agents may be used. Formulµ for suitable developing solutions incorporating the couplers are given. Compounds specified are the cyanacetylhydrazones of vanillin, piperonal, phenylacetaldehyde, crotonaldehyde, #-furylacrolein, terephthalaldehyde, pyruvic aldehyde, acetophenone, benzalacetone, mono-bromisatin, 5- nitro-7-methylisatin, cinnamaldehyde and ethyl alpha-phenylacetoacetate. Specification 590,637 is referred to.