Photothermographic material and image forming method
A photothermographic material including, on at least one side of a support, an image forming layer including at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder, wherein the photosensitive silver halide has an average silver iodide content of 40 mol % or higher, and the photothermographic material comprises a compound represented by the following formula (I) as the reducing agent: wherein R 1 , R 2 , R 3 , and R 4 each independently represent a hydrogen atom or a substituent; R 5 and R 6 each independently represent an alkyl group, an aryl group, a heterocyclic group, an acyl group, or a sulfonyl group; and R 7 represents R 11 —O—CO—, R 12 —CO—CO—, R 13 —NH—CO—, R 14 —SO 2 —, R 15 —W—C(R 16 )(R 17 )—, R 19 —SO 2 NHCO—, R 20 —CONHCO—, R 21 —SO 2 NHSO 2 —, R 22 —CONHSO 2 — or (M) 1/n OSO 2 —. A photothermographic material, which exhibits low fog and excellent storage stability, and an image forming method are provided.
1 . A photothermographic material comprising, on at least one side of a support, an image forming layer comprising at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder, wherein the photosensitive silver halide has an average silver iodide content of 40 mol % or higher, and the photothermographic material comprises a compound represented by the following formula (I) as the reducing agent:
wherein R 1 , R 2 , R 3 and R 4 each independently represent a hydrogen atom or a substituent; R 5 and R 6 each independently represent one selected from an alkyl group, an aryl group, a heterocyclic group, an acyl group, or a sulfonyl group; R 1 and R 2 , R 3 and R 4 , R 5 and R 6 , R 2 and R 5 , and/or R 4 and R 6 may bond to each other in each combination to form a 5-, 6-, or 7-membered ring; R 7 represents R 11 —O—CO—, R 12 —CO—CO—, R 13 —NH—CO—, R 14 —SO 2 —, R 15 —W—C(R 16 )(R 17 )—, R 19 —SO 2 NHCO—, R 20 —CONHCO—, R 21 —SO 2 NHSO 2 —, R 22 —CONHSO 2 —, or (M) 1/n OSO 2 —; R 11 , R 12 , R 13 , R 14 , R 19 , R 20 , R 21 , and R 22 each independently represent one selected from an alkyl group, an aryl group, or a heterocyclic group; R 15 represents a hydrogen atom or a block group; W represents an oxygen atom, a sulfur atom, or —N(R 18 )—; R 16 , R 17 and R 18 each independently represent one selected from a hydrogen atom or an alkyl group; and M represents a cation having a valency of n.
2 . The photothermographic material according to claim 1 , wherein the reducing agent represented by formula (I) is a compound in which R 7 in formula (I) represents R 11 —O—CO— or R 19 —SO 2 NHCO—.
3 . The photothermographic material according to claim 1 , wherein the photothermographic material further comprises a coupler, which reacts with an oxidation product of the reducing agent to form a dye.
4 . The photothermographic material according to claim 1 , wherein the reducing agent is a compound represented by the following formula (II):
wherein R 101 and R 102 each independently represent a substituted or unsubstituted alkyl group, aryl group, heterocyclic group, acyl group, alkylsulfonyl group, or arylsulfonyl group; R 103 , R 104 , R 105 , R 106 , and R 107 each independently represent a hydrogen atom or a substituent; members in at least one combination of R 101 and R 102 , R 103 and R 104 , R 105 and R 106 , and R 107 and X may bond to each other to form a 5-, 6-, or 7-membered ring; X represents a halogen atom or a substituent having a heteroatom (through which the substituent bonds to the benzene ring); n represents an integer of from 0 to 4; and when n represents 2 or more, a plurality of R 107 may be the same or different from one another and may bond to each other to form a 5-, 6-, or 7-membered ring.
5 . The photothermographic material according to claim 1 , wherein the reducing agent is a compound represented by the following formula (III):
wherein R 201 , R 202 , and R 203 each independently represent a hydrogen atom or a substituent; R 204 represents one selected from an alkyl group, an aryl group, or a heterocyclic group; R 201 , and R 202 , and/or R 202 and R 204 may bond to each other in each combination to form a 5-, 6-, or 7-membered ring; Z represents a non-metallic atomic group for forming a 5-, 6-, or 7-membered ring together with a nitrogen atom and two carbon atoms in a benzene ring; and R 205 represents one selected from an alkyl group, an aryl group, or a heterocyclic group.
6 . The photothermographic material according to claim 5 , wherein R 205 in formula (III) is a group represented by the following formula (IV):
wherein X represents a halogen atom or a group which substitutes for a hydrogen atom on a benzene ring through a heteroatom; R 206 represents a substituent; n represents an integer of from 0 to 4; and when n represents 2 or more, a plurality of R 206 may be the same or different from one another, and two adjacent groups thereamong may bond to each other to form a 5-, 6-, or 7-membered carbon ring or heterocycle.
7 . The photothermographic material according to claim 3 , wherein the coupler comprises at least one compound represented by a formula selected from the group consisting of the following formulae (C-1), (C-2), (C-3), (M-1), (M-2), (M-3), (Y-1), (Y-2), and (Y-3):
wherein X 1 represents a hydrogen atom or a leaving group; Y 1 and Y 2 each independently represent an electron-attracting substituent; and R 1 represents one selected from an alkyl group, an aryl group, or a heterocyclic group;
wherein X 2 represents a hydrogen atom or a leaving group; R 2 represents one selected from an acylamino group, a ureido group, or a urethane group; R 3 represents one selected from a hydrogen atom, an alkyl group, or an acylamino group; R 4 represents a hydrogen atom or a substituent; and R 3 and R 4 may link together to form a ring;
wherein X 3 represents a hydrogen atom or a leaving group; R 5 represents one selected from a carbamoyl group or a sulfamoyl group; and R 6 represents a hydrogen atom or a substituent;
wherein X 4 represents a hydrogen atom or a leaving group; R 7 represents one selected from an alkyl group, an aryl group, or a heterocyclic group; and R 8 represents a substituent;
wherein X 5 represents a hydrogen atom or a leaving group; R 9 represents one selected from an alkyl group, an aryl group, or a heterocyclic group; and R 10 represents a substituent;
wherein X 6 represents a hydrogen atom or a leaving group; R 11 represents one selected from an alkyl group, an aryl group, an acylamino group, or an anilino group; and R 12 represents one selected from an alkyl group, an aryl group, or a heterocyclic group;
wherein X 7 represents a hydrogen atom or a leaving group; R 13 represents one selected from an alkyl group, an aryl group, or an indolenyl group; and R 14 represents one selected from an aryl group or a heterocyclic group;
wherein X 8 represents a hydrogen atom or a leaving group; Z represents a bivalent group necessary for forming a 5- to 7-membered ring; and R 15 represents one selected from an aryl group or a heterocyclic group;
wherein X 9 represents a hydrogen atom or a leaving group; R 16 , R 17 , and R 18 each independently represent a substituent; n represents an integer of from 0 to 4; m represents an integer of from 0 to 5; when n represents 2 or more, a plurality of R 16 may be the same or different from one another; and when m represents 2 or more, a plurality of R 17 may be the same or different from one another.
8 . The photothermographic material according to claim 1 , wherein an average silver iodide content of the photosensitive silver halide is 80 mol % or higher.
9 . The photothermographic material according to claim 8 , wherein the average silver iodide content of the photosensitive silver halide is 90 mol % or higher.
10 . The photothermographic material according to claim 1 , wherein the photothermographic material further comprises a silver iodide complex-forming agent.
11 . The photothermographic material according to claim 10 , wherein the photothermographic material further comprises a compound represented by the following formula (PH):
wherein T represents one selected from a halogen atom (fluorine, bromine, or iodine), an alkyl group, an aryl group, an alkoxy group, or a nitro group; k represents an integer of from 0 to 4; and when k represents 2 or more, a plurality of T may be the same or different from one another.
12 . The photothermographic material according to claim 8 , wherein a mean grain size of the photosensitive silver halide is 0.20 μm or less.
13 . The photothermographic material according to claim 8 , wherein 50% or more of a total projected area of the photosensitive silver halide is occupied by tabular grains having an aspect ratio of 2 or more.
14 . The photothermographic material according to claim 13 , wherein a mean equivalent spherical diameter of the tabular silver halide grains is from 0.3 μm to 8.0 μm.
15 . The photothermographic material according to claim 13 , wherein the tabular silver halide grains have an epitaxial part.
16 . The photothermographic material according to claim 8 , wherein the photosensitive silver halide is subjected to chemical sensitization by at least one of chalcogen sensitization or gold sensitization.
17 . The photothermographic material according to claim 16 , wherein the photosensitive silver halide comprises a water-soluble thiocyanate in an amount of from 1×10 −3 mol to 8×10 −1 mol per 1 mol of silver halide.
18 . The photothermographic material according to claim 8 , wherein the photosensitive silver halide comprises a metal or a complex of metal belonging to groups 3 to 14 of the periodic table.
19 . The photothermographic material according to claim 8 , wherein the photothermographic material further comprises a compound having an adsorptive group and a reducing group.
20 . The photothermographic material according to claim 8 , wherein the photothermographic material further comprises a compound that is one-electron-oxidized to provide a one-electron oxidation product which releases one or more electrons.
21 . The photothermographic material according to claim 8 , wherein the photothermographic material further comprises a nitrogen-containing heterocyclic compound in which a mercapto group is substituted.
22 . The photothermographic material according to claim 1 , wherein an amount of coated silver is from 0.3 g/m 2 to 1.3 g/m 2 .
23 . An image forming method comprising imagewise exposing the photothermographic material according to claim 1 and thermally developing the photothermographic material.
24 . An image forming method comprising: bringing the photothermographic material according to claim 1 into close contact with a fluorescent intensifying screen; imagewise exposing the photothermographic material with X-rays; and thermally developing the photothermographic material.
25 . The image forming method according to claim 24 , wherein the fluorescent intensifying screen comprises a fluorescent substance in which 50% or more of the emission light has a wavelength of 350 nm to 420 nm.
26 . The image forming method according to claim 25 , wherein the fluorescent substance is a divalent Eu-activated barium halide fluorescent substance.