| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat developable sensitive material having high sensitivity and little fog, capable of giving high density and nearly free of the lowering of sensitivity even when preserved over a long period of time before exposure and development. SOLUTION: In the heat developable sensitive material containing at least one photosensitive silver halide emulsion, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder on one face of the base, the average equivalent circular diameter of the photosensitive silver halide emulsion is 10-50 nm and the emulsion is spectrally sensitized with two or more sensitizing dyes selected from dyes of formulae (I) and (II) [where L1-L11 are each methine; p1-p3 and q1 are each 0 or 1; n1 and n2 are each 0-4; Z1-Z4 are each a group of atoms required to form a nitrogen-containing heterocycle or the like; M1 and M2 are each a counter ion with equilibrated electric charges; m1 and m2 are each a number required to neutralize electric charges in each molecule; and R1-R4 are each alkyl, aryl or the like].
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