US Patent 7229753 Photothermographic material and method for forming images

A photothermographic material comprising at least (a) a photosensitive silver halide, (b) a reducible silver salt, (c) a reducing compound represented by the following general formula (1), and (d) a binder:Q1—NHNH—R1:   Formula (1)wherein, in the general formula (1), Q1 represents a 5- to 7-membered unsaturated ring bonding to NHNH—R1 at a carbon atom, and R1 represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group, provided that when R1 is propylcarbamoyl group, Q1 is not 2,3,5,6-tetrachloro-4-cyanophenyl group. According to the present invention, there is provided a novel photothermographic materials showing high sensitivity, high development speed and little fluctuation of performance due to heat development temperature variation.