Photothermographic material

1 . A photothermographic material comprising a substrate, and a photosensitive silver halide, a non-photosensitive organic silver salt, reducing agents for thermal development and a binder which are provided on the substrate, wherein:

the reducing agents for thermal development include a reducing agent which does not form a dye during thermal development and a reducing agent which forms a dye during thermal development; and

the reducing agent which forms a dye has higher activity than that of the reducing agent which does not form a dye.

2 . A photothermographic material according to claim 1 , wherein the reducing agent which does not form a dye is a compound represented by the general formula (R1), and the reducing agent which forms a dye is a compound represented by the following general formula (R2):

wherein R 11 and R 12 each independently represent a secondary or tertiary alkyl group; R 13 and R 14 each independently represent an alkyl group having a 2 or more carbon atoms; and R 15 represents an alkyl group:

wherein R 21 and R 22 each independently represent a secondary or tertiary alkyl group; R 23 and R 24 each independently represent a hydrogen atom, a hydroxyl group, an alkoxy group, an aryloxy group, an acyloxy group, an amino group or a heterocyclic group; and R 25 represents a hydrogen atom or an alkyl group.

3 . A photothermographic material according to claim 1 , wherein the reducing agent represented by general formula (R2) is contained in an amount of 40% by mol or less relative to a total amount of the reducing agents.

4 . A photothermographic material according to claim 2 , wherein the reducing agent represented by general formula (R2) is contained in an amount of 40% by mol or less relative to a total amount of the reducing agents.

5 . A photothermographic material according to claim 1 , which further comprises a development promoter.

6 . A photothermographic material according to claim 2 , which further comprises a development promoter.

7 . A photothermographic material according to claim 5 , wherein the development promoter contains at least one selected from the group consisting of a compound represented by the following general formulae (A-1) and a compound represented by the following general formula (A-2):

Q 1 -NHNH-Q 2   General formula (A-1)

wherein Q 1 represents an aromatic group or a heterocyclic group which bonds to —NHNH-Q 2 via a carbon atom; Q 2 represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group,

wherein R 1 represents an alkyl group, an acyl group, an acylamino group, an sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group; R 2 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonic acid ester group; and R 3 and R 4 each represent a group which is substitutable at a benzene ring, or couple with each other to form a condensed ring.

8 . A photothermographic material according to claim 6 , wherein the development promoter contains at least one selected from the group consisting of a compound represented by the following general formulae (A-1) and a compound represented by the following general formula (A-2):

Q 1 -NHNH-Q 2   General formula (A-1)

wherein Q 1 represents an aromatic group or a heterocyclic group which bonds to —NHNH-Q 2 via a carbon atom; Q 2 represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group,

wherein R 1 represents an alkyl group, an acyl group, an acylamino group, an sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group; R 2 represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonic acid ester group; and R 3 and R 4 each represent a group which is substitutable at a benzene ring, or couple with each other to form a condensed ring.

9 . A photothermographic material according to claim 1 , which further comprises a hydrogen bond-forming compound.

10 . A photothermographic material according to claim 2 , which further comprises a hydrogen bond-forming compound.

11 . A photothermographic material according to claim 7 , which further comprises a hydrogen bond-forming compound.

12 . A photothermographic material according to claim 8 , which further comprises a hydrogen bond-forming compound.

13 . A photothermographic material according to claim 9 , wherein the hydrogen bond-forming compound is a compound represented by the following general formula (D):

wherein R 21 to R 23 each independently represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group.

14 . A photothermographic material according to claim 1 , which comprises a compound represented by the following general formula (H);

Q-(Y) n —C(Z 1 )(Z 2 )X  General formula (H)

wherein Q represents an alkyl group, an aryl group or a heterocyclic group; Y represents a divalent linking group; Z 1 and Z 2 each represent a halogen atom; X represents a hydrogen atom or an electron withdrawing group; and n represents 0 or 1.

15 . A photothermographic material according to claim 1 , wherein a total amount of coated silver is 1.9 g/m 2 or less.

16 . A photothermographic material according to claim 1 , wherein thermal developing is completed within 16 seconds.