Dry silver photothermographic compsns.

摘要

Dry silver type photosensitive compsns. are made comprising (a) a light-insensitive silver cpd. (I) which on reduction undergoes a visible change, (b) sufficient of a silver halide to catalyst the reduction of the (I) in those areas where the silver halide has been exposed to light and when the mixt. is heat in the presence of a reducing agent, and (c) an acutance dye of formula (II) in which R1 is 1-12C alkyl; R2 is H, 1-4C alkyl, a phenyl gp., a substd. phenyl gp. with a mol. wt. of <350, -COOR1, C6H5CO- or R6NH.CO in which R6 is H, alkyl, aryl or aralkyl; R3, R4 and R5 are H or a substituent which can be present in a cyanine by type heterocyclic nucleus; D is O, S, Se, > C(CH3)2 or > NR7 in which R7 is 1-4C alkyl or CH3COO-; Y is -CN or -NO2; n = 1 when k = 0 or K = 1 when n = 0; and m = 0, 1 or 2. Cpd. (II) where Y is NO2 is claimed per se. The (II) are used in dry silver photothermographic materials which are developed by heating without the use of photographic processing solns.