SPECTRAL SENSITIZING DYES FOR PHOTOTHERMOGRAPHIC ELEMENTS

摘要

The present invention provides heat-developable, photothermographic elements comprising a support bearing at least one photosensitive, image-forming layer comprising: (a) a photosensitive silver halide; (b) a non-photosensitive, reducible silver source; (c) a reducing agent for silver ions; (d) a binder; and (e) a spectrally sensitizing amount of a compound having the central nucleus, represented by formula (I), wherein: Z is S, O, Se or N-R<3>; R<1> and R<2> represent an alkyl group of from 1 to 20 carbon atoms other than carboxy-substituted alkyl, preferably an alkyl group of from 1 to 8 carbon atoms, and most preferably an ethyl group; and R<3> is H or alkyl group; X and Y are thioalkyl groups of from 1 to 20 carbon atoms; n = 0 to 4; m = 0 to 4; the sum of n plus m equals at least 1; D<1> to D<7> each independently represents a methine group and adjacent methine groups selected from D<2>, D<3>, D<4>, D<5> and D<6> may form cyclic groups; p = 0 or 1; and A<-> is an anion.