Silver halide photothermographic materials - contg. a heterocyclic hydrazone reducing agent whose oxidn. prod. reacts with a dye-forming coupler to form an image dye

摘要

Sensitive photothermographic material comprises a support carrying at least one layer comprising a binder, a photographic silver halide, a dye-forming coupler and a hydrazone reducing agent (I) contg. a heterocyclic nucleus comprising a 5- or 6-membered heterocyclic ring, and of which an oxidn. prod. reacts with the coupler to form an image dye. Pref. (I) has the formula in which n is 0 or 1; R1 is H or 1-20C acyl gp.; R2 is H, -COR4 or -SO2R4; R3 is 1-20C alkyl, alkenyl or alkynyl, 5-8C cycloalkyl, 6-12C aryl, heterocyclic gp. with a 5- or 6-membered heterocyclic ring, -COR4 or -SO2R4; R4 is OH, amino, 1-20C alkyl, or 6-12C aryl; Z completes a 5- or 6-membered heterocyclic ring; and the gps. R1, R2,R3, R4 and Z may be further substd. Pref. cpds. (I) are those in which R1 and R2 are H, R3 is methyl and n is 0. The (I) may be in salt form. Multicolour images can be produced by using photographic silver halide layers of different spectral sensitivities and contg. dye-forming couplers giving image dyes of different colours on reaction with the oxidn. prod. of the (I). The materials may be constructed as diffusion transfer sets in which the dye image produced on heating is transferred by diffusion at an elevated temp. to an integral or separate receiving layer.