Photothermographic material

1 . A photothermographic material comprising, on a support, an image forming layer comprising at least a photosensitive silver halide, a non-photosensitive organic silver salt, and a reducing agent for silver ions, and a non-photosensitive layer, wherein the non-photosensitive layer comprises at least an anionic water-soluble dye, a fixing agent for the water-soluble dye, and an acid generator.

2 . The photothermographic material according to claim 1 , wherein the acid generator is a compound which generates an acid by heating.

3 . The photothermographic material according to claim 1 , wherein the anionic water-soluble dye is a metal phthalocyanine dye represented by the following formula (PC-1):

wherein M represents a metal atom; R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 each independently represent a hydrogen atom or a substituent; at least one of R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 is an electron-attracting group; and R 2 , R 3 , R 6 , R 7 , R 10 , R 11 , R 14 , and R 15 each independently represent a hydrogen atom or a substituent.

4 . The photothermographic material according to claim 3 , wherein at least one of R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 of the metal phthalocyanine dye represented by formula (PC-1) is a group represented by formula (II):

-L 1 -R 17   Formula (II)

wherein L 1 represents one selected from **—SO 2 —*, **—SO 3 —*, **—SO 2 NR N —*, **—SO—*, **—CO—*, **—CONR N —*, **—COO—*, **—COCO—*, **—COCO 2 —*, or **—COCONR N —*; ** denotes a bond with a phthalocyanine skeleton at this position; * denotes a bond with R 17 at this position; R N represents one selected from a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, a carbamoyl group, a sulfonyl group, or a sulfamoyl group; and R 17 represents one selected from a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

5 . The photothermographic material according to claim 4 , wherein four or more from among R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 of the metal phthalocyanine dye represented by formula (PC-1) are each independently a group represented by formula (II).

6 . The photothermographic material according to claim 4 , wherein R 2 , R 3 , R 6 , R 7 , R 10 , R 11 , R 14 , and R 15 of the metal phthalocyanine dye represented by formula (PC-1) are each a hydrogen atom, and at least one of R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 is a group represented by formula (II).

7 . The photothermographic material according to claim 6 , wherein four or more from among R 1 , R 4 , R 5 , R 8 , R 9 , R 12 , R 13 , and R 16 of the metal phthalocyanine dye represented by formula (PC-1) are each independently a group represented by formula (II).

8 . The photothermographic material according to claim 1 , wherein the acid generator is a compound represented by the following formula (1):

W 1 (OP 1 ) k   Formula (1)

wherein W 1 represents a residue of an acid represented by W 1 (OH) k ; P 1 each independently represents a substituent which leaves due to heat; and k represents 1 or 2.

9 . The photothermographic material according to claim 8 , wherein the compound represented by formula (1) is at least one selected from the group consisting of a compound represented by the following formula (2), (3), or (4) and a polymer of a compound represented by the following formula (2), (3), or (4):

wherein R 1 represents an electron-attracting group having a Hammett substituent constant σp of greater than 0; R 2 represents an alkyl group which may have one or more substituents; R 3 represents a group which leaves due to heat; and W 1 has the same meaning as in formula (1);

wherein R 4 , R 5 , and R 6 each independently represent a hydrogen atom, an alkyl group which may have one or more substituents, or an aryl group which may have one or more substituents; and W 1 has the same meaning as in formula (1);

P 2 —X-L-C(R 7 )(R 8 )—OW 1   Formula (4)

wherein P 2 represents a substituent which leaves due to heat; X represents O, S, NR 9 , or CR 10 R 11 ; R 9 , R 10 , R 11 , R 7 , and R 8 each independently represent a hydrogen atom or a substituent; L represents a linking group; and W 1 has the same meaning as in formula (1).

10 . The photothermographic material according to claim 1 , wherein the acid generator is a compound represented by the following formula (5) or (6):

wherein R 1 represents one selected from a chlorine atom, a hydroxy group, an alkyl group, an alkoxy group, an alkylthio group, an —OM group, an —NR 1 R 2 group, or an —NHCOR 3 group; R 1 , R 2 , and R 3 each independently represent a hydrogen atom, an alkyl group, or an aryl group; M represents a monovalent metal atom; and R 2 represents a group having the same meaning as R 1 excluding a chlorine atom;

wherein R 3 and R 4 each independently represent one selected from a chlorine atom, a hydroxy group, an alkyl group, an alkoxy group, or an —OM group; M represents a monovalent metal atom; Q and Q′ each independently represent a linking group selected from the group consisting of —O—, —S—, and —NH—; L represents an alkylene group or an arylene group; and l and m each independently represent 0 or 1.

11 . The photothermographic material according to claim 1 , wherein the acid generator is a compound represented by the following formula (7):

wherein R 5 and R 6 each independently represent a halogen atom, a cyano group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a hydroxy group, a substituted amino group, or a group selected from an alkyl group, alkenyl group, alkynyl group, aryl group, or heterocyclic group having 1 to 30 carbon atoms, each of which may have a substituent; R 5 and R 6 may bond to each other to form a ring; Z 1 represents a 5- or 6-membered cyclic group having at least two carbon atoms and one nitrogen atom; and W 1 represents an alkyl group or an aryl group, each of which may have a substituent.

12 . The photothermographic material according to claim 1 , wherein the fixing agent is a polymer compound containing a vinyl monomer unit having a tertiary amino group or a quaternary ammonio group represented by any one of the following formulae (FX-1) to (FX-4):

wherein R 1 represents a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms; L represents a divalent linking group having 1 to 20 carbon atoms; E represents a heterocyclic group containing a nitrogen atom having a double bond with a carbon atom as a constituent component; and n is 0 or 1;

wherein R 1 , L, and n each have the same meaning as in formula (FX-1); R 4 and R 5 each independently represent an alkyl group having 1 to 12 carbon atoms or an aralkyl group having 7 to 20 carbon atoms; and R 4 and R 5 may be linked with each other to form a cyclic structure together with a nitrogen atom;

wherein R 1 , L, and n each have the same meaning as in formula (FX-1); G + represents a heterocycle which contains a nitrogen atom that is quaternarized and has a double bond with a carbon atom as a constituent component; and X − represents a monovalent anion;

wherein R 1 , L, and n each have the same meaning as in formula (FX-1); R 4 and R 5 each have the same meaning as in formula (FX-2); R 6 independently has the same meaning as R 4 and R 5 ; X − has the same meaning as in formula (FX-3); and R 4 , R 5 , and R 6 may be linked with one another to form a cyclic structure together with a nitrogen atom.

13 . The photothermographic material according to claim 1 , wherein the image forming layer is disposed on one side of the support, and the non-photosensitive layer is disposed on the other side of the support.

14 . The photothermographic material according to claim 13 , wherein a film surface pH at the side having thereon the non-photosensitive layer after thermal development is lower by at least 0.2 than that before thermal development.