JP2002278016A - Heat developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having low fog and good preservability, satisfying high sensitivity, high Dmax (maximum density) and a high color tone, having small temperature and humidity dependencies in development and optimum for a medical diagnostic image. SOLUTION: The heat developable photosensitive material has an image forming layer containing a non-photosensitive organic silver salt, photosensitive silver halide, a reducing agent for silver ions and a binder on one face of the base. When the material is heat-developed under the conditions of 121 deg.C and 24 see after exposure, >=90% of developed silver contacts with the photosensitive silver halide grains after development. The photosensitive silver halide has been chemically sensitized with a noble metal sensitizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material. More specifically, the present invention relates to a photothermographic material having excellent photographic performance and image storability, high sensitivity and excellent color tone.

[0002]

2. Description of the Related Art In recent years, in the field of medical diagnostic films and photoengraving films, there has been a strong demand for reduction of processing waste liquid from the viewpoint of environmental protection and space saving. Therefore, heat-development is possible as a medical diagnostic film and a photoengraving film that can be efficiently exposed by a laser imagesetter or a laser imager and can form a clear black image having high resolution and sharpness. There is a need for techniques relating to photosensitive materials. According to these photothermographic materials, a photothermographic processing system that does not require solution-based processing chemicals, is simpler and does not damage the environment can be supplied to customers.

There is a similar requirement in the field of general image forming materials. Particularly, medical diagnostic images require high-quality images with excellent sharpness and granularity due to the need for fine description. There is a feature that a cool black image is preferred from the viewpoint of easiness. At present, various hard copy systems using pigments and dyes, such as ink jet printers and electrophotographs, are distributed as general image forming systems, but none of them is satisfactory as a medical image output system.

On the other hand, thermal image forming systems utilizing organic silver salts are disclosed in, for example, US Pat. Nos. 3,152,904 and 3,457,075 and D.C. Crosta Bohr (K
Losterboer, "Thermal Processed Si System"
Lever Systems) "(Imaging Processes and Materials (Imaging P
processesand Materials) Neb
lette 8th edition, J.M. Sturge,
V. Walworth, A.M. Shepp Editing, Chapter 9, p. 279, 1989
Year). In particular, the photothermographic material generally comprises a catalytically active amount of a photocatalyst (for example, silver halide), a reducing agent, a reducible silver salt (for example, an organic silver salt), and if necessary, a color toning agent for controlling the color tone of silver. And a photosensitive layer (image forming layer) dispersed in a binder matrix. The photothermographic material is exposed to a high temperature (for example, 80
C. or higher) to form a black silver image by an oxidation-reduction reaction between a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposed area. It is disclosed in many documents including U.S. Pat. No. 2,910,377 and JP-B-43-4924.

A photothermographic material does not require a processing agent and does not discharge a large amount of waste material. For this reason, the photothermographic material has been spreading in the market as an excellent system with less environmental load, which has been emphasized in recent years. In addition, especially for medical diagnostic images, fine description is required, so high image quality with excellent sharpness and granularity is required, and cool-tone images are preferred from the viewpoint of ease of diagnosis. , Low fog, good preservation, high sensitivity, high Dma
It has been desired to provide a photothermographic material that satisfies x (highest density) and high color tone, and is most suitable for medical diagnostic images with little temperature dependence and temperature dependence during development.

[0006]

In view of these problems of the prior art, the present invention provides low fog, good storability, high sensitivity, high Dmax (maximum density) and high color tone, and It is an object of the present invention to provide a photothermographic material that is most suitable for medical diagnostic images having small temperature and temperature dependence.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors can provide a photothermographic material exhibiting an intended effect by selecting and combining materials used for an image forming layer. The inventors have found that the present invention has been achieved. That is, the present invention provides: <1> a photothermographic method having, on one surface of a support, an image forming layer containing a non-photosensitive organic silver salt, a photosensitive silver halide, a reducing agent for silver ions, and a binder. 90% or more of the developed silver, which is thermally developed at 121 ° C. for 24 seconds after exposure, is in contact with the photosensitive silver halide grains after development, and Is a photothermographic material characterized by being chemically sensitized with a noble metal sensitizer.

<2> The noble metal sensitizer is a compound represented by the following general formula (a): <1>
Is a photothermographic material. General formula (a) [L-Au-L] M (wherein L represents an organic mercapto ligand and M represents a cationic counter ion, provided that the complex is symmetric.)

<3> The noble metal sensitizer is a compound represented by the following general formula (b): <1>
Or the photothermographic material of <2>. General formula (b) [Au (R) ₂ ] ⁺ X ⁻ (wherein, R represents a ligand, and two Rs may be the same or different from each other, and at least one is a mesoionic coordination. .X representing the child ^- represents an anion).

<4> The image forming layer contains a compound represented by the following general formula (D).
1> to <3>. General formula (D) Q ¹ -NHNH-Q ² [In general formula (D), Q ¹ is a carbon atom and represents -NHNH
An aromatic group or a heterocyclic group bonded to -Q ^2, Q ²
Represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group. ]

<5> The photothermographic material according to any one of <1> to <4>, wherein in the compound represented by formula (D), Q ² is a carbamoyl group.

In this specification, "to" indicates a range that includes numerical values described before and after it as a minimum value and a maximum value, respectively.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The photothermographic material of the present invention will be described below in detail. The photothermographic material of the present invention comprises a non-photosensitive organic silver salt (hereinafter may be referred to as "organic silver salt"), a photosensitive silver halide, and a reducing agent for silver ions on one surface of a support. And an image forming layer containing a binder. The feature is that the photosensitive silver halide is chemically sensitized by a noble metal sensitizer. The photothermographic material of the present invention that satisfies these conditions has low fog, good storability, high sensitivity and high Dma.
x (maximum density) and high color tone, and has the advantage of low temperature and low temperature dependence during development.

Further, in the photothermographic material of the present invention, 90% or more of the developed silver when thermally developed at 121 ° C. for 24 seconds after exposure comes into contact with the above-mentioned photosensitive silver halide grains after development. It is necessary to be. The photothermographic material of the present invention has the advantage that the silver tone of the output image becomes a cool black tone by satisfying such conditions, and thus can be optimally used as a medical diagnostic image. here,
"Developed silver" means silver produced by thermally developing the photothermographic material and using the non-photosensitive organic silver salt as a silver source. The ratio of the developed silver in contact with the silver halide grains after the development can be determined as follows. The Dmax portion of the photothermographic material of the present invention, which has been exposed and thermally developed, is cut using a diamond knife in a direction perpendicular to the support surface to produce an ultrathin section. The thickness of the ultrathin section is 0.1 to 0.2 μm, and the length and width may be any size. Next, the ultrathin section was placed on a mesh and observed with a transmission electron microscope. The number (x) of the developed silver in contact with the silver halide grains and the development without contact with the silver halide grains were determined. The number of silver (y) is counted, and the number of all developed silver (x + y) is counted.
The above ratio can be calculated by determining the ratio (100x / (x + y)) of the number of developed silver in contact with the silver halide grains to the silver halide grains. Hereinafter, the materials used for the photothermographic material of the present invention will be described in order.

First, the photosensitive silver halide used in the present invention will be described. The photosensitive silver halide used in the present invention is not particularly limited as a halogen composition, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver iodochlorobromide can be used. The distribution of the halogen composition in the grains may be uniform, the halogen composition may change stepwise, or may change continuously. Further, silver halide grains having a core / shell structure can be preferably used. Preferred as the structure is a two- to five-fold structure, more preferably a core / shell particle having a two- to four-fold structure. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. Specifically, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound to gelatin or another polymer solution,
Thereafter, a method of mixing with an organic silver salt is preferably used. Also preferred are the methods described in paragraphs [0217] to [0224] of JP-A-11-119374, and the methods described in Japanese Patent Application Nos. 11-98708 and 11-84182.

The size of the photosensitive silver halide grains is preferably small for the purpose of suppressing white turbidity after image formation, specifically, 0.20 μm or less, more preferably 0.1 μm or less.
01 μm to 0.15 μm, more preferably 0.02 μm
０．１0.12 μm is preferred. The grain size as used herein refers to a diameter when converted into a circular image having the same area as the projected area of a silver halide grain (projected area of a main plane in the case of a tabular grain).

The shape of the silver halide grains is cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned. In the present invention, cubic particles are particularly preferable. Grains having rounded corners of silver halide grains can also be preferably used. The surface index (mirror index) of the outer surface of the photosensitive silver halide grains is not particularly limited. However, the spectral sensitization efficiency when the spectral sensitizing dye is adsorbed is high. preferable. The ratio is preferably at least 50%, more preferably at least 65%, even more preferably at least 80%. The ratio of the {100} plane of the Miller index is determined by the T.V. method utilizing the dependence of the adsorption of the sensitizing dye on the {111} plane and the {100} plane. Tani; Imaging Sc
i. , 29, 165 (1985).

In the present invention, it is preferable to use silver halide grains having a hexacyano metal complex present on the outermost surface of the grains. As the hexacyano metal complex, [Fe (CN)
₆ ] ^{4 −} , [Fe (CN) ₆ ] ³⁻ , [Ru (CN) ₆ ] ⁴⁻ ,
[Os (CN) ₆ ] ^4- , [Co (CN) ₆ ] ^3- , [Rh
(CN) ₆ ] ^3- , [Ir (CN) ₆ ] ^3- , [Cr (CN)
₆ ] ^3- , [Re (CN) ₆ ] ^{3- and the} like. In the present invention, it is preferable to use a hexacyano Fe complex.

Since the hexacyano metal complex exists in the form of ions in an aqueous solution, its counter cation is not important. However, it is easily miscible with water and is compatible with sodium ion and potassium which are suitable for the precipitation operation of a silver halide emulsion. Use of alkali metal ions such as ions, rubidium ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetra (n-butyl) ammonium ion) Is preferred.

The hexacyano metal complex is prepared by mixing a water-miscible organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides, etc.) in addition to water or gelatin. And can be added as a mixture.

The addition amount of the hexacyano metal complex is preferably 1 × 10 ⁻⁵ mol to 1 × 10 ⁻² mol, more preferably 1 × 10 ⁻⁴ mol to 1 × 10 ⁻³ mol per mol of silver. .

In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grains, the addition of the hexacyano metal complex to the silver nitrate aqueous solution used for forming the grains is completed, and then noble metal sensitization such as gold sensitization is required. Accordingly, before the completion of the charging step, before the chemical sensitization step for performing sulfur sensitization, selenium sensitization, and tellurium sensitization chalcogen sensitization, etc., during the washing step, during the dispersion step, or directly before the chemical sensitization step. Added. In order not to grow the silver halide fine grains, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add the hexacyano metal complex before the completion of the charging step.

Incidentally, the addition of the hexacyano metal complex may be started after 96% by mass of the total amount of silver nitrate added for grain formation is added, or started after 98% by mass is added. More preferably, it is particularly preferable after adding 99% by mass.

When these hexacyano metal complexes are added after the addition of an aqueous solution of silver nitrate immediately before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grains, and most of them are hardly soluble in silver ions on the grain surface. Forms salt. Since the silver salt of hexacyanoiron (II) is a salt that is less soluble than AgI, it can be prevented from being redissolved by fine particles,
It becomes possible to produce silver halide fine grains having a small grain size.

The photosensitive silver halide grains can contain a metal or a metal complex of Group 8 to Group 10 of the periodic table (showing Groups 1 to 18). Rhodium, ruthenium, and iridium are preferably the metals of Groups 8 to 10 of the periodic table or the central metal of the metal complex. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol per mol of silver. These heavy metals and metal complexes and their addition methods are described in JP-A-7-225449,
No. 65021, paragraph numbers [0018] to [002]
4], JP-A-11-119374, paragraph [02]
27] to [0240].

Further, metal atoms (for example, [Fe] which can be contained in the silver halide grains used in the present invention.
(CN) ₆ ] ^4- ), desalting and chemical sensitization of silver halide emulsions are described in paragraphs [0046] to [0050] of JP-A-11-84574 and JP-A-11-6502.
No. 1 paragraph numbers [0025] to [0031], and JP-A-11-119374 paragraph numbers [0242] to [0]
250].

Various gelatins can be used as the gelatin contained in the photosensitive silver halide emulsion used in the present invention. In order to maintain a good dispersion state of the photosensitive silver halide emulsion in the coating solution containing an organic silver salt, it is preferable to use low molecular weight gelatin having a molecular weight of 500 to 60,000. These low molecular weight gelatins may be used at the time of particle formation or at the time of dispersion after desalting, but are preferably used at the time of dispersion after desalting.

In the present invention, the photosensitive silver halide is noble gold
Photosensitized silver halide chemically sensitized with a genus sensitizer
Used. Examples of the noble metal sensitizer include gold, platinum, and palladium.
And iridium. In particular, use gold sensitizer
Preferably, specifically, chloroauric acid, potassium
Chloroaurate, potassium aurithiocyanate, sulfuric acid
Gold halide, gold selenide, etc .;
10 per liter^-7-10 ^-2mol can be used
You.

In the present invention, it is also preferable to use a sulfur sensitizer, a selenium sensitizer, a tellurium sensitizer, and a noble metal sensitizer in combination. When used in combination with gold sensitization, for example, sulfur sensitization and gold sensitization, selenium sensitization and gold sensitization, sulfur sensitization and selenium sensitization and gold sensitization, Sulfur sensitization, tellurium sensitization, and gold sensitization, and sulfur sensitization, selenium sensitization, tellurium sensitization, and gold sensitization are preferable.

As the noble metal sensitizer, a compound represented by the following formula (a) (hereinafter sometimes referred to as "organic mercapto gold (I) complex") is preferable. General formula (a) [L-Au-L] M wherein the complex is symmetrical, that is, L is the same. In the formula, L represents an organic mercapto ligand. L is an organic mercapto ligand suitable for use in a silver halide photographic element and has antifogging, stability or sensitizing properties. Many such ligands are known in the art and all are commercially available or can be prepared according to the methods described in Research Disclosure 274 (1984). Suitable examples of L include thiol ligands having a hydrophilic substituent such as mercaptoazoles, examples of which are described in U.S. Patent Nos. 3,266,897 and 4,607,0.
No. 04, No. 3,266,897, No. 4,
Nos. 920,043, 4,912,026, 5,011,768 and British Patent 1,275,701.

In the formula, M represents a cationic counter ion. M
Is preferably an alkali metal ion (for example, potassium ion, sodium ion or cesium ion), or an ammonium cation (for example, tetrabutyl or tetraethylammonium cation).

The organic mercapto gold (I) complex is preferably a complex represented by the following general formula (a '). General formula (a ′) [( ^{MR sol} ) _n -AS-Au- ^SA- (R ^sol −
M) _n ] M wherein R ^sol represents a hydrophilic group. The hydrophilic group _{^{R sol, -OSO 3 -, -}} SO 3 -, - SO 2 -, - PO 3
-Or -COO- is preferred. n represents any one of 1 to 4, and when n is 2 or more, n (R ^sol -M) _n may be the same or different. However, this complex is symmetric.

M represents a cationic counter ion. M is preferably an alkali metal ion (eg, potassium ion, sodium ion or cesium ion), or an ammonium cation (eg, tetrabutyl or tetraethylammonium cation).

In the formula, A represents a substituted or unsubstituted divalent organic group. A is preferably an aliphatic (cyclic or acyclic), aromatic or heterocyclic divalent group. A may further have a substituent. When A is an aliphatic group, A has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms.
Is preferably a substituted or unsubstituted aliphatic group.
Examples of suitable groups include alkylene groups (e.g., ethylene, methylene, propylene, butylene, pentylene, hexylene, octylene, 2-ethylhexylene, decylene, dodecylene, hexadecylene, Includes octadecylene, cyclohexylene, isopropylene and tert-butylene groups.

When A is an aromatic group, A has from 6 to 6 carbon atoms.
It is preferably an aromatic group having 20 and more preferably an aromatic group having 6 to 10 carbon atoms, and particularly preferably a phenylene group and a naphthylene group. When A is a heterocyclic group, A is a substituted or unsubstituted divalent 3- to 15-membered ring having at least one atom selected from nitrogen, oxygen, sulfur, selenium and tellurium in the ring nucleus. The ring is preferably a 5- to 6-membered ring having at least one (particularly preferably two or more) nitrogen atoms. Examples of heterocyclic groups include pyrrolidine, piperidine, pyridine, tetrahydrofuran, thiophene, oxazole, thiazole, imidazole, benzothiazole, benzoxazole, benzimidazole, selenazole, benzoselenazole, tellurazole, triazole, benzotriazole, tetrazole, oxazole It includes a divalent group of a diazole or thiadiazole ring. A preferred heterocyclic group is tetrazole.

Unless otherwise specified, the substituents which can be substituted on the above-mentioned molecules include any groups, whether substituted or unsubstituted, which do not destroy the properties necessary for photographic practicality. When the term "group" is applied to the identification of a substituent containing a substitutable hydrogen, it includes not only the unsubstituted form of the substituent, but also any group (s) described herein. It is intended to include the form further substituted by. These groups are preferably attached to the residue of the molecule by a carbon, silicon, oxygen, nitrogen, phosphorus or sulfur atom.

Suitable substituents for A include, for example, halogens such as chlorine, bromine or fluorine; nitro; hydroxyl; cyano; carboxyl; or optionally further substituted groups, for example linear or branched. Alkyl groups including alkyl (eg, methyl group, trifluoromethyl group, ethyl group, tert-butyl group, 3- (2,
4-di-tert-amylphenoxy) propyl group and tetradecyl group); alkenyl groups such as ethylene group and 2-butene group; methoxy group, ethoxy group, propoxy group, butoxy group, 2-methoxyethoxy group, s
ec-butoxy group, hexyloxy group, 2-ethylhexyloxy group, tetradecyloxy group, 2- (2,4-
Alkoxy groups such as di-tert-pentylphenoxy) ethoxy group and 2-dodecyloxyethoxy group; phenyl group, 4-tert-butylphenyl group,
Aryl groups such as 2,4,6-trimethylphenyl and naphthyl; phenoxy, 2-methylphenoxy, α- or β-naphthyloxy, and 4
An aryloxy group such as a tolyloxy group; an acetamido group, a benzamide group, a butylamide group, a tetradecaneamide group, an α- (2,4-di-tert-pentyl-
Phenoxy) acetamide group, α- (2,4-di-te)
rt-pentylphenoxy) butylamide group, α- (3
-Pentadecylphenoxy) -hexaneamide group, α-
(4-hydroxy-3-tert-butylphenoxy)
-Tetradecaneamide group, 2-oxo-pyrrolidine-1
-Yl group, 2-oxo-5-tetradecylpyrroline-1
-Yl group, N-methyltetradecaneamide group, N-succinimide group, N-phthalimido group, 2,5-dioxo-1-oxazolidinyl group, 3-dodecyl-2,5-dioxo-1-imidazolyl group, N-acetyl -N-dodecylamino group, ethoxycarbonylamino group, phenoxycarbonylamino group, benzyloxycarbonylamino group, hexadecyloxycarbonylamino group, 2,4
-Di-tert-butylphenoxycarbonylamino group, phenylcarbonylamino group, 2,5- (di-te
rt-pentylphenyl) carbonylamino group, p-dodecylphenylcarbonylamino group, p-toluylcarbonylamino group, N-methylureido group, N, N-dimethylureido group, N-methyl-N-dodecylureido group, N- Hexadecylureido group, N, N-dioctadecylureide group, N, N-dioctyl-N′-ethylureide group, N-phenylureido group, N, N-diphenylureido group, N-phenyl-Np-toluyl Ureido group, N- (m-hexadecylphenyl) ureido group,
N, N- (2,5-di-tert-pentylphenyl)
A —N′-ethylureido group, and a carboxamide group such as tert-butylcarbonamide;

A methylsulfonamide group, a benzenesulfonamide group, a p-toluylsulfonamide group, a p-dodecylbenzenesulfonamide group, an N-methyltetradecylsulfonamide group, an N, N-dipropylsulfamoylamino group, A sulfonamide group such as a decylsulfonamide group; an N-methylsulfamoyl group;
N-ethylsulfamoyl group, N, N-dipropylsulfamoyl group, N-hexadecylsulfamoyl group,
N, N-dimethylsulfamoyl group, N- [3- (dodecyloxy) propyl] sulfamoyl group, N- [4-
(2,4-di-tert-pentylphenoxy) butyl] sulfamoyl group, N-methyl-N-tetradecylsulfamoyl group, and sulfamoyl groups such as N-dodecylsulfamoyl group; N-methylcarbamoyl group; N, N-dibutylcarbamoyl group, N-octadecylcarbamoyl group, N- [4- (2,4-di-tert
-Pentylphenoxy) butyl] carbamoyl group, N-
A methyl-N-tetradecylcarbamoyl group, and N,
Carbamoyl groups such as N-dioctylcarbamoyl group; acetyl group, (2,4-di-tert-amylphenoxy) acetyl group, phenoxycarbonyl group, p-dodecyloxyphenoxycarbonyl group, methoxycarbonyl group, butoxycarbonyl group, tetra Acyl groups such as decyloxycarbonyl, ethoxycarbonyl, benzyloxycarbonyl, 3-pentadecyloxycarbonyl, and dodecyloxycarbonyl; methoxysulfonyl, octyloxysulfonyl, tetradecyloxysulfonyl, Ethylhexyloxysulfonyl group, phenoxysulfonyl group, 2,4-
Di-tert-pentylphenoxysulfonyl group, methylsulfonyl group, octylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, hexadecylsulfonyl group, phenylsulfonyl group, 4-nonylphenylsulfonyl group, and p-toluylsulfonyl group A sulfonyl group such as a dodecylsulfonyloxy group and a hexadecylsulfonyloxy group;

Sulfinyl groups such as methylsulfinyl group, octylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, hexadecylsulfinyl group, phenylsulfinyl group, 4-nonylphenylsulfinyl group and p-toluylsulfinyl group; ethylthio Group, octylthio group, benzylthio group, tetradecylthio group, 2- (2,4-di-ter
thio groups such as t-pentylphenoxy) ethylthio, phenylthio, 2-butoxy-5-tert-octylphenylthio and p-toluylthio; acetyloxy, benzoyloxy, octadecanoyloxy, p -Dodecylamidobenzoyloxy group, N
Acyloxy groups such as phenylcarbamoyloxy, N-ethylcarbamoyloxy and cyclohexylcarbonyloxy; phenylanilino, 2-
Amine groups such as chloroanilino group, diethylamine group, dodecylamine group; imino groups such as 1- (N-phenylimido) ethyl group, N-succinimide group or 3-benzylhydantoinyl group; dimethylphosphate group and ethyl Phosphate groups such as butyl phosphate groups; phosphite groups such as diethyl and dihexyl phosphite groups; substituted groups such as 2-furyl, 2-thienyl, 2-benzimidazolyloxy or 2-benzothiazolyl groups, respectively. May be
And a heterocyclic group, a heterocyclic oxy group or a heterocyclic thio group, each having a carbon atom and a 3- to 7-membered heterocyclic ring composed of at least one heteroatom selected from the group consisting of oxygen, nitrogen and sulfur; A quaternary ammonium group such as a triethylammonium group; and a silyloxy group such as a trimethylsilyloxy group. A particularly preferred substituent of A is a benzamide group.

In general, the above groups and their substituents are
It will have up to 48 carbon atoms, typically 1-36, usually less than 24, although higher numbers of carbon atoms are possible depending on the particular substituents selected.

When A is substituted, (R ^sol -M) _n
May be bonded to the substituent. A- (R ^sol-
One preferred example of M) _n (where n is 1) is represented by the following general formula.

[0043]

Embedded image

Specific examples of the organic mercapto gold (I) complex include the following, but the gold (I) complex used in the present invention is not limited to these. In addition,
In the following structural formula, "Ac" represents an acetyl group.

[0045]

Embedded image

[0046]

Embedded image

[0047]

Embedded image

[0048]

Embedded image

Examples of the organic mercapto gold (I) complex include the exemplified compound (S) and potassium bis (1- [3- (2
-Sulfonatobenzamido) phenyl] -5-mercaptotetrazole potassium salt) aurate (I) pentahydrate is particularly preferred.

One advantage of the complexes of the present invention is their solubility in water. The solubility is preferably 2 g / L at 22 ° C., more preferably 5 g / L, and 10 g.
/ L is most preferred. Particularly preferred compounds are 20
It has a solubility of more than g / L.

The organic mercapto gold (I) complex may be a gold
(I) reacting the complex with an organic mercapto ligand to obtain
Of the resulting organic mercapto gold (I) complex from the reaction mixture
Manufactured separately. Suitable gold (I) complex for use in this method
The body is more positive than the desired organic mercapto gold (I) complex
Since it has a redox potential of
Facilitates replacement. Such compounds are known to those skilled in the art.
is there. Examples of useful gold (I) complexes include AuCl_Two ^-, Au
Br_Two ^-, Au (MeS-CH_Two-CH_Two-CHNH _TwoCO
OH)_Two ⁺, Au (CNS)_Two ^-, AuI or Au
(NH_Three)_Two ⁺Of which AuI is particularly preferred.

Since the gold (I) complex may be somewhat unstable, it is preferred to react the gold (III) compound with a stoichiometric amount of a reducing agent to prepare the gold (I) complex immediately before use. . As the gold (III) compound, any compound that can be reduced to form a stable gold (I) complex can be used. Many of these compounds are commercially available. Examples of suitable compounds include KAuBr _4, KAuCl _4, and HAuCl _4. Examples of the reducing agent include tetrahydrothiophene, 2,2′-thiodiethanol, thiourea, N, N′-tetramethylthiourea, alkyl sulfides (eg, dimethyl sulfide, diethyl sulfide, diisopropyl sulfide), thiomorpholine-
3-one, sulfite, bisulfite, uridine, uracil, alkali hydride and iodide (Us
on, R. Laguna, A .; Laguna, M .;
Inorg. Synth. 1989, 26, 85-9
1; Al-Saady, A .; K. McAuliff;
e, C.I. A. Parish, R .; V. ; Sandba
nk, J. et al. A. Inorg. Synth. 1985, 2
3, 191-194; Ericson, A .; Eldi;
ng, L .; I. Elmroth, S .; K. C. J .;
Chem. Soc. , Dalton Trans. 19
97, 7, 1159-1164; Elding, L .;
I. Olsson, L .; F. Inorg. Chem.
1982, 21, 779-784;
G. FIG. Canovese, L .; Cattalini,
L. Natile, G .; J. Chem. Soc. , D
alton Trans. 1980, 7, 1017-1
021). In some cases, the reduction can be carried out under a stabilizer such as potassium chloride (Miller, J. et al.
B. Burmeister, J .; L. Synth. R
eact. Inorg. Met. -Org. Chem.
1985, 15, 223-233). In some cases, it is desirable to isolate the resulting gold (I) compound (ie, to avoid unwanted side reactions). For example, in the case of AuI, removing excess iodine is desirable to avoid deleterious sensitometric effects. Depending on the stability of the resulting gold (I) compound, isolation may not be practical.

The gold (I) complex / organic mercapto reaction is preferably carried out in an aqueous system, but this is not essential, as shown in the examples. In general, no operation other than mixing or stirring the reactants for a short time, preferably at a temperature slightly above room temperature, is required. The gold (I) compound is treated with at least two equivalents of a water-soluble organic mercapto ligand (preferably, a water-soluble salt of the ligand). To obtain a symmetric organic mercapto gold (I) complex, one type of organic mercapto ligand is used. Preferably, the organic mercaptide ligand can be represented by the following general formula. (M-R ^sol ) _n -A- ^{SM In the} formula, M, R ^sol , A and n represent the general formula (a ′)
M, R ^sol , A, and n in the above are the same as each other.
Preferred organic mercaptide ligands are 1- [3- (2
-Sulfonatobenzamido) phenyl] -5-mercaptotetrazole potassium salt.

A very wide range of temperatures, preferably from room temperature to
This reaction can be carried out at 100C, more preferably at 30-50C. In general, the reaction is the natural p of the system.
H and no adjustment is required. About 4 to 7.5
A pH of about 6 is preferred, while a pH of about 6 is most preferred. In many cases, the reaction of the gold (I) complex with the organic mercapto ligand occurs in only a few minutes at a temperature of 30 ° C., depending on the reactants. Especially unstable gold (I)
When using a complex, Cl ^- it can stabilize the system by adding a stabilizing electrolyte such as ^- or Br.

Performing the isolation of the gold (I) product obtained by a suitable method, for example by treating the reaction mixture with several equivalents of an alkali halide or adding a water-miscible non-solvent. Can be. A preferred isolation method is
Generally, it is necessary to cool the reaction solution after introducing the alkali halide. This material is isolated by suction filtration and treated with a cold aqueous alcohol detergent such as butanol, isopropanol, ethanol and the like. This procedure is simple and does not require complicated operations or multiple recrystallizations.

As the noble metal sensitizer, a compound represented by the following formula (b) (hereinafter sometimes referred to as “gold (I) compound”) is also preferable. General formula (b) [Au (R) ₂ ] ⁺ X ⁻

In the general formula (b), R represents a ligand;
Two Rs may be the same or different from each other;
At least one represents a mesoionic ligand. X ^- is a halogen ion and BF ₄ ^- represents the like anions. Where X
^- is not intended to be limited to a monovalent anion.

These compounds can be dissolved in various solvents including water or organic solvents (for example, acetone or methanol), but the most preferred compounds are water-soluble compounds. As used herein, the term “water-soluble” means that the gold (I) compound has a standard pressure and a temperature of 20.
It means dissolving in water at a concentration of at least 10 ^-5 mol / L at ° C.

In the general formula (b), the meso-ion ligand represented by R is coordinated with the gold (I) ion, and is water-soluble and enables chemical sensitization of the silver halide photographic composition. To form a gold (I) compound. As the meso-ion ligand, a ligand represented by the following general formula is preferable.

[0060]

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In the formula, a circle having a + sign in the heterocyclic ring is a symbolic representation of six delocalized π electrons combined with a partial positive charge on the heterocyclic ring.

Wherein a, b, c, d and e are the unsubstituted or substituted atoms required to complete the mesoionic ligand, for example a mesoionic triazolium or tetrazolium 5-membered heterocycle. Represents the carbon and nitrogen atoms required to complete. Components of the heterocyclic ring (a, b, c,
d and e) can be selected from CR ⁵ groups, NR ⁵ ′ groups, nitrogen atoms and chalcogen atoms. The minus sign indicates two additional electrons on the exocyclic group f conjugated to the six π electrons on the heterocycle. There is extensive delocalization and the charge shown is only a fraction of the charge. Exocyclic group f
Is preferably selected from S, Se and R ⁵ ″. R ⁵ represents a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group or a heterocyclic group.
⁵ ′ is a hydrogen atom, a substituted or unsubstituted alkyl group,
Represents an aryl group or a heterocyclic group. R ⁵ ″ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. R ⁵ , R ⁵ ′ and R ⁵ ″ are combined to form another ring be able to.

The mesoionic ligand is described in Advances in Hes by Ollis and Ramsden.
terocyclic Chemistry, 19,
Academic Press, London (19
76) can also be used. The mesoionic ligand represented by the above general formula can coordinate to gold (I) via an exocyclic group f. From the viewpoint of the stability of the organic gold compound, the exocyclic group f is preferably not O (oxygen atom).

The above general formula representing a mesoionic ligand has a circle representing six delocalized π electrons in the heterocyclic moiety, but does not mean aromaticity.

The compound represented by the general formula (b) includes
The compound represented by the following general formula (1b) is included.

Formula (1b)

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In the formula, R ^6a , R ^7a and R ^8a each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, an amino group or a substituted or unsubstituted aryl group. (X ^{a) -} is a halogen ion or BF ₄ ^- represents a. Preferred compounds are shown in the following table.

[0068]

[Table 1]

The compound represented by the general formula (b) includes a compound represented by the following general formula (2b).

Formula (2b)

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[0071] Here, R ^6b, R ^7b and (X ^{b) -} the above R ^6a, R ^7a and (X ^{a) -} and are each synonymous. Preferred compounds are shown in the following table.

[0072]

[Table 2]

The compound represented by the general formula (b) includes a compound represented by the following general formula (3b).

Formula (3b)

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In the formula, R ^6c , R ^7c , R ^8c and R ^9c each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, an amino group, a substituted or unsubstituted aryl group the stands, (X ^{c) -} is halogen or BF ₄ ^- represents a. Preferred compounds are shown in the following table.

[0076]

[Table 3]

The meso-ionic compound used as a starting material for producing the gold (I) compound containing the meso-ionic ligand includes Altland, Dedio and Mc
The method described in US Pat. No. 4,378,424 to Sweeney (1983);
It can be made by methods described in the overview of lis and Ramsden and the references cited therein. The synthesis of the gold (I) compound can be performed by various techniques known in the art. For example, a method of reacting a gold (I) precursor compound with an appropriate amount of a mesoionic compound is preferable. In subsequent reactions, typically performed at room temperature (about 20 ° C.) or slightly above room temperature, for several minutes, the ligand of the gold (I) precursor compound will be converted to a meso-ion with a higher affinity for gold (I). Is replaced with a ligand. The product can then be separated and purified by crystallization techniques.

Various substituents on the mesoionic ligand affect the solubility of the final product gold (I) compound. The most desirable gold (I) compounds are those that are soluble in water and can be made in water. Further, the aqueous emulsion can be sensitized by using one dissolved in an organic solvent such as acetone, or the emulsion can be sensitized by a non-aqueous medium. Regarding this gold compound, US Pat. No. 5,049,
No. 485 is described in more detail.

In the present invention, it is preferable to use a compound represented by the following general formula (b ') at the time of chemical sensitization of silver halide.

Formula (b ')

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In the general formula (b ′), X ′ is —O—, —N
Represents H- or -NR'-, and R 'represents an alkyl group, a fluoroalkyl group, an aryl group or a sulfonyl group. m and r are each independently 0, 1 or 2
Wherein m and r are not both 0. M represents -H or a cationic chemical species, and Ar represents an aromatic group.
L ² represents a linking group, and p represents 0 or 1. In addition,
In the above formula, (m + r) X ′, M, L ² and p and two Ars may be the same or different from each other.

In the general formula (b ′), Ar represents a monocyclic or condensed-ring aromatic group, preferably having 6 to 10 carbon atoms.
More preferably, it has 6 carbon atoms. Examples of suitable aromatic groups include naphthyl and phenyl. Ar may be further substituted or unsubstituted, but Ar is more preferably substituted. Examples of suitable substituents include alkyl groups (eg,
Methyl group, ethyl group, hexyl group), fluoroalkyl group (for example, trifluoromethyl group), alkoxy group (for example, methoxy group, ethoxy group, octyloxy group), aryl group (for example, phenyl group, naphthyl group,
Tolyl group), hydroxyl group, halogen atom, aryloxy group (for example, phenoxyl group), alkylthio group (for example, methylthio group, butylthio group), arylthio group (for example, phenylthio group), acyl group (for example,
Acetyl, propionyl, butyryl, valeryl), sulfonyl (eg, methylsulfonyl, phenylsulfonyl), acylamino, sulfonylamino, acyloxy (eg, acetoxy, benzoxy), carboxyl, cyano Groups, sulfo groups, and amino groups. Preferred are simple alkyl and acylamino groups.

In the general formula (b ′), X ′ is —O—, —N
Represents H- or -NR-. Most preferred X 'is -NH
-. When X 'is -NR-, R is a substituent that does not interfere with the intended function of the disulfide compound in the photographic element and maintains the compound's water solubility. Examples of suitable substituents include alkyl groups (eg, methyl, ethyl, hexyl), fluoroalkyl groups (eg, trifluoromethyl), aryl groups (eg, phenyl, naphthyl, tolyl), sulfonyl groups (eg, methyl Sulfonyl, phenylsulfonyl). Preferred are simple alkyl groups and simple fluoroalkyl groups.

In the general formula (b ′), r and m independently represent 0, 1 or 2. Preferably, m and r are both 1. X ′ may be bonded at any position to the sulfur in the aromatic group Ar. Preferably, the molecule is symmetrical and X 'is preferably located para or ortho to sulfur in the aromatic group Ar.

In the general formula (b ′), L ² represents a linking group.
p represents 0 or 1. Preferably, L ² is an unsubstituted alkylene group, usually-(CH ₂ ) _n- (where
The range of n is preferably from 0 to 11, and more preferably from 1 to 3. Then shows another example of L ^2.

[0086]

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M represents a hydrogen atom or a cationic chemical species (when the ionized form has a carboxyl group).
The cationic species include metal cations and organic cations. Examples of organic cations include ammonium ions (eg, ammonium, tetramethylammonium, tetrabutylammonium), phosphonium ions (eg, tetraphenylphosphonium), and guanidyl groups. M is preferably a hydrogen atom or an alkali metal cation, most preferably a sodium or potassium ion.

Examples of the disulfide compound represented by the general formula (b ′) (exemplified compounds II-A to II-Z) are shown below. Compounds II-A to II-H are preferred, and compounds II-D and II-E are most preferred.

[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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The disulfide compound represented by the general formula (b ′) can be easily prepared using easily available starting materials. Most of the disulfide compounds are
The free diacid can be obtained by reacting aminophenyl disulfide or hydroxyphenyl disulfide with a suitable cyclic anhydride and then converting the free diacid to its anionic form using a substance such as sodium bicarbonate. Aminophenyl disulfide or hydroxyphenyl disulfide can be reacted with the monochloride of a dicarboxylic acid monoester, which can then be hydrolyzed to the carboxylic acid to give other soluble disulfides. The disulfide compound is disclosed in US Pat. No. 5,418,12.
No. 7 is discussed.

In the present invention, a sensitizing dye can be used. As the sensitizing dye, a dye capable of spectrally sensitizing silver halide grains in a desired wavelength region when adsorbed on silver halide grains and having a spectral sensitivity suitable for the spectral characteristics of the exposure light source is advantageously selected. be able to. For sensitizing dyes and addition methods, see paragraphs [0103] to [0109] of JP-A-11-65021, and JP-A-10-186.
No. 572, a compound represented by the general formula (II), JP-A-11-119374, a dye represented by the general formula (I) and paragraph [0106], US Pat.
Nos. 236 and 3,871,887, the dyes described in Example 5, the dyes disclosed in JP-A-2-96131 and JP-A-59-48753, European Patent Publication EP No. 0803764A1, page 19, line 38 to page 20, line 35, Japanese Patent Application 2000-8
No. 6865, Japanese Patent Application No. 2000-102560, and the like. These sensitizing dyes may be used alone or in combination of two or more. In the present invention, the timing of adding a sensitizing dye to a silver halide emulsion is as follows.
The period after the desalting step and before coating is preferable, and more preferably the period after desalting and before the start of chemical ripening. The addition amount of the sensitizing dye in the present invention can be a desired amount in accordance with the sensitivity and fogging performance, but is preferably 10 ^-6 to 1 mol per mol of silver halide in the image forming layer.
More preferably, it is 10 ^-4 to 10 ^-1 mol.

In the present invention, in order to improve the spectral sensitization efficiency,
Supersensitizers can be used. Examples of the supersensitizer used in the present invention include EP 587,338, U.S. Pat. Nos. 3,877,943 and 4,873,184, and JP-A-5-873. 341432
Gazettes, JP-A-11-109947 and JP-A-10-111
No. 543, and the like.

The photosensitive silver halide grains in the present invention may be used in combination with a sulfur sensitization method, a selenium sensitization method or a tellurium sensitization method. As the compound preferably used in the sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds, for example, compounds described in JP-A-7-128768 and the like can be used. Particularly, in the present invention, tellurium sensitization is preferable, and compounds described in the literature described in JP-A-11-65021, paragraph [0030],
General formula (II) in JP-A-5-313284,
Compounds represented by (III) and (IV) are more preferred.

In the present invention, chemical sensitization can be carried out at any time after grain formation and before coating, and after desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, ( 3)
After spectral sensitization, there may be (4) just before coating. In particular, it is preferably performed after spectral sensitization. The amount of the sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains to be used, the conditions of chemical ripening, etc., but is preferably 10 ^-8 to 10 ^-2 mol, preferably 10 ^-8 mol, per mol of silver halide. About 10 ^-7 to 10 ^-3 mol is used. The conditions for the chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is 40 to 40.
It is about 95 ° C. A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method described in European Patent Publication No. EP 293,917.

The light-sensitive silver halide emulsion in the heat-developable image recording material used in the present invention may be of one type or two types.
Species or more (eg, those having different average grain sizes, different halogen compositions, different crystal habits, and different chemical sensitization conditions) may be used in combination. The gradation can be adjusted by using a plurality of photosensitive silver halides having different sensitivities. Japanese Patent Application Laid-Open No.
No. 119341, No. 53-106125, No. 47-3929, No. 48-55730, No. 46-5187, No. 50-73627, No. 57-150841, and the like. Technology. The sensitivity difference was 0.2 log for each emulsion.
It is preferable to have a difference of E or more.

The amount of the photosensitive silver halide added is 0.03 to 0.03, expressed as the amount of silver applied per m ^{2 of the} photothermographic material.
It is preferably 0.6 g / m ² , and 0.05 to 0.1 g / m ² .
4 g / m ² is more preferable, and 0.1 to 0.1 g / m ² .
The amount is most preferably 4 g / m ² , and the amount of the photosensitive silver halide is 0.01 mol to 0.1 mol per 1 mol of the organic silver salt.
5 mol is preferable, and 0.02 mol to 0.3 mol is more preferable.

Regarding the method of mixing the photosensitive silver halide and the organic silver salt separately prepared and the mixing conditions, the silver halide particles and the organic silver salt which have been respectively prepared are mixed with a high-speed stirrer, a ball mill, a sand mill, a colloid mill, and a vibrator. Mills, a method of mixing with a homogenizer, etc., or a method of preparing an organic silver salt by mixing photosensitive silver halide prepared at any timing during the preparation of the organic silver salt, etc. There is no particular limitation as long as the effect appears sufficiently. In addition, mixing two or more kinds of aqueous dispersions of organic silver salts and two or more kinds of aqueous dispersions of photosensitive silver salts is a preferable method for adjusting photographic characteristics.

The preferred timing of adding silver halide to the coating solution for the image forming layer is from 180 minutes to immediately before coating, preferably from 60 minutes to 10 seconds before coating. There is no particular limitation as long as the effect of (1) fully appears. As a specific mixing method, there is a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time,
Harnby, M .; F. Edwards, A. et al.
W. Nienow, translated by Koji Takahashi “Liquid mixing technology”
(Nikkan Kogyo Shimbun, 1989), a method using a static mixer described in Chapter 8 and the like.

The image forming layer in the invention preferably contains a compound represented by the following formula (D). General formula (D) Q ¹ -NHNH-Q ² (wherein Q ¹ represents an aromatic group or a heterocyclic group bonded to —NHNH-Q ² at a carbon atom, and Q ² represents a carbamoyl group, an acyl group, Represents an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, or a sulfamoyl group)

The aromatic or heterocyclic group represented by Q ¹ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a 1,2,4-triazine ring,
1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,
2,4-triazole ring, tetrazole ring, 1,3,4
A thiadiazole ring, a 1,2,4-thiadiazole ring,
1,2,5-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, 1,
A 2,5-oxadiazole ring, a thiazole ring, an oxazole ring, an isothiazole ring, an isoxazole ring, a thiophene ring and the like are preferable, and a condensed ring in which these rings are condensed with each other is also preferable.

These rings may have a substituent,
When it has two or more substituents, those substituents may be the same or different. Examples of the substituent include a halogen atom, an alkyl group, an aryl group, a carbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a carbamoyl group, a sulfamoyl group, and a cyano group. Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have a substituent, and examples of preferred substituents include:
Halogen atom, alkyl group, aryl group, carbonamide group, alkylsulfonamide group, arylsulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group ,
Cyano group, sulfamoyl group, alkylsulfonyl group,
An arylsulfonyl group and an acyloxy group can be mentioned.

The carbamoyl group represented by Q ² is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as unsubstituted carbamoyl,
Methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbamoyl, N-sec-butylcarbamoyl, N-octylcarbamoyl, N-cyclohexylcarbamoyl, N-tert-butylcarbamoyl, N-
Dodecylcarbamoyl, N- (3-dodecyloxypropyl) carbamoyl, N-octadecylcarbamoyl,
N- {3- (2,4-tert-pentylphenoxy)
Propyl carbamoyl, N- (2-hexyldecyl)
Carbamoyl, N-phenylcarbamoyl, N- (4-
Dodecyloxyphenyl) carbamoyl, N- (2-chloro-5-dodecyloxycarbonylphenyl) carbamoyl, N-naphthylcarbamoyl, N-3-pyridylcarbamoyl, N-benzylcarbamoyl.

The acyl group represented by Q ² is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, Octanoyl, 2-hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, 2-hydroxymethylbenzoyl. The alkoxycarbonyl group represented by Q ² is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, for example,
Methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl,
Dodecyloxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ² is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms.
Phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxymethylphenoxycarbonyl, 4-dodecyloxyphenoxycarbonyl are exemplified. The sulfonyl group represented by Q ² is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, Dodecyloxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, 4-dodecyloxyphenylsulfonyl.

The sulfamoyl group represented by Q ² preferably has 0 to 50 carbon atoms, more preferably 6 to 40 carbon atoms.
For example, unsubstituted sulfamoyl, N-ethylsulfamoyl group, N- (2-ethylhexyl) sulfamoyl, N-decylsulfamoyl,
N-hexadecylsulfamoyl, N- {3- (2-ethylhexyloxy) propyl} sulfamoyl, N-
(2-chloro-5-dodecyloxycarbonylphenyl) sulfamoyl and N- (2-tetradecyloxyphenyl) sulfamoyl. The group represented by Q ² may further have, at a substitutable position, the group exemplified as the substituent for the 5- to 7-membered unsaturated ring represented by Q ¹ above. When it has two or more substituents, those substituents may be the same or different.

Next, the preferred range of the compound represented by the formula (D) will be described. As Q ¹ , a 5- to 6-membered unsaturated ring is preferable, and a benzene ring, a pyrimidine ring, 1,2,3
-Triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,2
4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring,
Oxazole rings, isothiazole rings, isoxazole rings, and rings obtained by condensing these rings with a benzene ring or an unsaturated hetero ring are more preferred. Q ² is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on a nitrogen atom. Hereinafter, specific examples of the compound represented by Formula (D) are shown, but the compounds used in the present invention are not limited to these specific examples. In the structural formula of the present specification, (t) is ter.
(i) is an abbreviation for iso, and an unsubstituted alkyl group or the like is a straight chain (nor)
mal).

[0113]

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[0114]

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[0115]

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[0116]

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[0117]

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[0118]

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[0119]

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[0120]

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[0121]

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[0122]

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[0123]

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[0124]

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Compounds represented by formula (D) are described in JP-A-9-152702 and JP-A-8-286340,
No. 9-152700, No. 9-152701, No. 9-152703, and No. 9-1527
It can be synthesized according to the method described in JP-A No. 04-2004 and the like. The compound represented by the general formula (D) may be added to the material by any method such as a solution, a powder, a solid fine particle dispersion, an emulsion, and an oil protection dispersion. The dispersion of the solid fine particles is carried out by a known fine means (for example, ball mill, vibrating ball mill, sand mill, colloid mill, jet mill, roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used. It is preferable to use the compound of the general formula (D) in the range of 0.01 to 100 mol% based on the reducing agent. A more preferred amount is in the range of 0.1 to 50 mol%, more preferably 0.5 to 20 mol%, most preferably 1 to 1 mol%, based on the reducing agent.
The range is 0 mol%.

The image forming layer in the invention may contain a hydrogen bonding compound. As used herein, the term "hydrogen bonding compound" refers to a non-reducing compound having a group capable of forming a hydrogen bond with a compound having an OH group and / or an NH group. Examples of a group capable of forming a hydrogen bond with an OH group or an NH group include a phosphoryl group,
Examples include a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (provided that they have no> NH group and are blocked like> NR (R is a substituent other than H)), and a urethane group. (However, it has no> NH group and is blocked like> NR (R is a substituent other than H)), ureido group (however, it has no> NH group, and> It is a compound having NR (R is blocked like a substituent other than H).

In the present invention, a compound represented by the following formula (II) is particularly preferred as the hydrogen bonding compound.

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In the general formula (II), R ¹¹ , R ¹² and R ¹³ each independently represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group. May be substituted or have a substituent, and any two of R ¹¹ , R ¹² and R ¹³ may be substituted.
One may combine with each other to form a ring. When R ¹¹ , R ¹² and R ¹³ have a substituent, the substituent includes a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group,
Arylthio group, sulfonamide group, acyloxy group,
Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group, and are preferably an alkyl group or an aryl group. Specific examples include a methyl group, an ethyl group, an isopropyl group, and a tert group.
-Butyl group, tert-octyl group, phenyl group, 4-
Examples include an alkoxyphenyl group and a 4-acyloxyphenyl group.

Specific examples of the groups represented by R ¹¹ , R ¹² and R ¹³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a tert-butyl group, a tert-amyl group, a substituted or unsubstituted alkyl group such as a tert-octyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a phenethyl group, a 2-phenoxypropyl group; a phenyl group, a cresyl group,
Substituted or unsubstituted aryl groups such as xylyl group, naphthyl group, 4-tert-butylphenyl group, 4-tert-octylphenyl group, 4-anisidyl group, 3,5-dichlorophenyl group; methoxy group, ethoxy group, butoxy group An octyloxy group, a 2-ethylhexyloxy group,
Substituted or unsubstituted alkoxyl groups such as 3,5,5-trimethylhexyloxy group, dodecyloxy group, cyclohexyloxy group, 4-methylcyclohexyloxy group, benzyloxy group; phenoxy group, cresyloxy group, isopropylphenoxy group, 4- substituted or unsubstituted aryloxy groups such as tert-butylphenoxy group, naphthoxy group, biphenyloxy group; amino group, dimethylamino group, diethylamino group, dibutylamino group,
Dioctylamino group, N-methyl-N-hexylamino group, dicyclohexylamino group, diphenylamino group,
Substituted or unsubstituted amino groups such as N-methyl-N-phenylamino group; 2-pyridyl group, 4-pyridyl group, 2-
Furanyl group, 4-piperidinyl group, 8-quinolyl group, 5
-A heterocyclic group such as a quinolyl group.

R ¹¹ , R ¹² and R ¹³ are preferably an alkyl group, an aryl group, an alkoxy group or an aryloxy group. From the viewpoint of the effects of the present invention, one or more of R ¹¹ , R ¹² and R ¹³ are preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. Further, it is preferable that R ¹¹ , R ¹² and R ¹³ are the same group in that they can be obtained at low cost.

The specific examples of the compounds represented by formula (II) are shown below, but the compounds which can be used in the present invention are not limited to these.

[0132]

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[0133]

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[0134]

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[0135]

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The hydrogen bonding compound can be contained in a coating solution in the form of a solution, an emulsified dispersion or a solid dispersion of fine particles in the same manner as the reducing agent, and can be used in the photothermographic material. The hydrogen-bonding compound forms a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state, and depending on the combination of the reducing agent and the hydrogen-bonding compound, is isolated in a crystalline state as a complex. be able to. It is particularly preferable to use the crystal powder isolated in this way as a solid dispersion fine particle dispersion in order to obtain stable performance. Further, a method in which a reducing agent and a hydrogen bonding compound are mixed in a powder form, and a suitable dispersant is used to form a complex at the time of dispersion with a sand grinder mill or the like can also be preferably used. The hydrogen bonding compound is added to the reducing agent in an amount of 1 to 2
It is preferably used in the range of 00 mol%,
More preferably, it is used in the range of 50 mol%.
More preferably, it is used in the range of 100 mol% to 100 mol%.

Next, the binder used for the photosensitive layer in the photothermographic material of the present invention will be described. In the present invention, the binder used in the photosensitive layer (that is, the organic silver salt-containing layer) may be any type of polymer,
Suitable binders are transparent or translucent, generally colorless, and include natural resins and polymers and copolymers, synthetic resins and polymers and copolymers, and other film-forming media, and more specifically, for example, gelatins , Rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrate, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) s,
Poly (methyl methacrylic acid), Poly (vinyl chloride)
, Poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, poly (vinyl acetal) s (for example, poly (vinyl formal) and Poly (vinyl butyral)), poly (ester), poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), poly ( Olefin)
, Cellulose esters, poly (amides) and the like. The binder may be coated from water or an organic solvent or emulsion.

In the present invention, the glass transition temperature of the binder in the layer containing the organic silver salt is preferably from 10 ° C. to 80 ° C. (hereinafter sometimes referred to as a high Tg binder), and preferably from 20 ° C. to 70 ° C. More preferably, 23 ° C.
More preferably, it is -65 ° C.

In this specification, Tg was calculated by the following equation. 1 / Tg = Σ (Xi / Tgi) Here, it is assumed that the polymer has copolymerized n monomer components from i = 1 to n. Xi is the mass fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer.
Where Σ is the sum of i = 1 to n. The homopolymer glass transition temperature (Tgi) of each monomer is Pol
ymer Handbook (3rd Edition
n) (J. Brandrup, EH Immerg)
ut (Wiley-Interscience, 19
89)) was adopted.

The polymer serving as a binder may be used alone or as a combination of two or more as necessary.
Further, those having a glass transition temperature of 20 ° C. or higher and those having a glass transition temperature of less than 20 ° C. may be used in combination.
When two or more polymers having different Tg are blended and used, the weight average Tg is preferably in the above range.

In the present invention, the organic silver salt-containing layer is applied by using a coating solution in which 30% by mass or more of the solvent is water,
When formed by drying, when the binder of the organic silver salt-containing layer is further soluble or dispersible in an aqueous solvent (aqueous solvent), particularly when the binder of the organic silver salt-containing layer is at 25 ° C. and 60% RH. When the polymer latex has an equilibrium water content of 2% by mass or less, the performance as a photothermographic material is improved. The most preferred form has an ionic conductivity of 2.
This is the case where a binder prepared to be 5 mS / cm or less is used. As such a preparation method, a method of purifying using a separation functional membrane after polymer synthesis is exemplified.

The aqueous solvent in which the polymer is soluble or dispersible is water or a mixture of water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include, for example, alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol;
Examples thereof include cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

The term “aqueous solvent” is used herein even in the case where the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The “equilibrium moisture content at 25 ° C. and 60% relative humidity” is defined as the mass W ^{1 of the} polymer in humidity control equilibrium in an atmosphere of 25 ° C. and 60% relative humidity and the weight of the polymer in a completely dry state at 25 ° C. It can be expressed as follows using the mass W ⁰ . Equilibrium water content at 25 ° C. and 60% relative humidity = ｛(W ¹ −
W ⁰ ) / W ⁰ ｝ × 100 (% by mass)

The definition and measurement method of the water content can be referred to, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by the Society of Polymer Science, Jinjinshokan).

The equilibrium water content of the binder polymer of the present invention at 25 ° C. and a relative humidity of 60% is preferably 2% by mass or less, more preferably 0.01% by mass to 1% by mass.
5% by mass, more preferably 0.02% by mass to 1% by mass
It is. 95

In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersion state include a latex in which fine particles of a water-insoluble hydrophobic polymer are dispersed and a dispersion in which polymer molecules are dispersed in a molecular state or in the form of micelles, all of which are preferable. The average particle size of the dispersed particles is 1 to 50000 nm, more preferably 5 to 50000 nm.
The range is about 1000 nm. There is no particular limitation on the particle size distribution of the dispersed particles, and they may have a broad particle size distribution or a monodispersed particle size distribution.

In the present invention, preferable polymers dispersible in an aqueous solvent include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethane) s, poly (vinyl chloride) s, and poly (vinyl chloride) s. Vinyl acetate)
, Poly (vinylidene chloride) s, and poly (olefins). These polymers may be a linear polymer, a branched polymer, a crosslinked polymer, a so-called homopolymer obtained by polymerizing a single monomer, or a copolymer obtained by polymerizing two or more kinds of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of these polymers is 5000 in number average molecular weight.
~ 1,000,000, more preferably 1
0000 to 200,000. If the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

Specific examples of preferable polymer latex include the following. The following polymer latex is represented by using a raw material monomer, and the numerical value in parentheses is% by mass, and the molecular weight is the number average molecular weight. When a polyfunctional monomer is used, the concept of molecular weight cannot be applied because a crosslinked structure is formed. Tg represents a glass transition temperature.

P-1; -MMA (70) -EA (27)
-MAA (3)-latex (molecular weight 37000) P-2; -MMA (70) -2EHA (20) -St
Latex of (5) -AA (5)-(molecular weight 4000
0) P-3; -St (50) -Bu (47) -MAA (3)
-Latex (crosslinkable) of P-4; -St (68) -Bu (29) -AA (3)-
Latex (crosslinkability) P-5; -St (71) -Bu (26) -AA (3)-
Latex (crosslinkable, Tg 24 ° C) P-6; -St (70) -Bu (27) -IA (3)-
Latex (crosslinkable) P-7; -St (75) -Bu (24) -AA (1)-
Latex (crosslinkable) P-8; -St (60) -Bu (35) -DVB (3)
-MAA (2)-latex (crosslinkable) P-9; -St (70) -Bu (25) -DVB (2)
-AA (3)-latex (crosslinkable) P-10; -VC (50) -MMA (20) -EA (2
Latex of 0) -AN (5) -AA (5)-(molecular weight: 80000) P-11; -VDC (85) -MMA (5) -EA
Latex of (5) -MAA (5)-(molecular weight 6700
0) Latex of P-12; -Et (90) -MAA (10)-(molecular weight 12000) P-13; -St (70) -2EHA (27) -AA
Latex of (3) (molecular weight 130000) P-14; -MMA (63) -EA (35) -AA
Latex of (2) (molecular weight 33000) P-15; -St (70.5) -Bu (26.5) -A
A (3) -latex (crosslinkable, Tg 23 ° C) P-16; -St (69.5) -Bu (27.5) -A
A (3) -latex (crosslinkable, Tg 20.5 ° C)

The abbreviations in the above structures represent the following monomers. MMA; methyl methacrylate EA; ethyl acrylate MAA; methacrylic acid 2EHA; 2-ethylhexyl acrylate St; styrene Bu; butadiene AA; acrylic acid DVB; divinylbenzene VC; vinyl chloride AN; acrylonitrile VDC; vinylidene chloride Et; ethylene IA;

The above-mentioned polymer latex is commercially available, and the following products can be used. Examples of acrylic polymers include Sebian A-4635, 4718,
4601 (all manufactured by Daicel Chemical Industries, Ltd.), Nipo
Examples of poly (esters) such as lx811, 814, 821, 820, 857 (all manufactured by Nippon Zeon Co., Ltd.) include FINETEX ES650, 611, 67
5,850 (all manufactured by Dainippon Ink and Chemicals, Inc.), WD-
Examples of poly (urethane) s such as size and WMS (all manufactured by Eastman Chemical) include HYDRAN
Examples of rubbers such as AP10, 20, 30, 40 (all manufactured by Dainippon Ink and Chemicals, Inc.) include LACSTAR.
7310K, 3307B, 4700H, 7132C
(Dai Nippon Ink Chemical Co., Ltd.), Nipol Lx
Examples of poly (vinyl chloride) s such as 416, 410, 438C, and 2507 (all manufactured by Zeon Corporation) include:
G351, G576 (all manufactured by Nippon Zeon Co., Ltd.), etc.
Examples of poly (vinylidene chloride) s include L502, L
Examples of poly (olefin) s such as 513 (all manufactured by Asahi Kasei Corporation) include Chemipearl S120, SA10
0 (both manufactured by Mitsui Petrochemical Co., Ltd.).

These polymer latexes may be used alone, or may be used in combination of two or more as required.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The mass ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 40:60 to 95: 5. The proportion of the copolymer of styrene monomer units and butadiene monomer units is 60 to 99% by mass.
It is preferred that The preferred molecular weight range is the same as described above.

The styrene-butadiene copolymer latex preferably used in the present invention includes the aforementioned P-3
~ P-8, 14, 15, LACSTAR- which is a commercial product
3307B, 7132C, Nipol Lx416 and the like.

The organic silver salt-containing layer of the photothermographic material of the present invention may optionally contain a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose or carboxymethylcellulose as a binder. . The amount of these hydrophilic polymers to be added is preferably 30% by mass or less, more preferably 20% by mass or less of the total binder in the organic silver salt-containing layer.

The organic silver salt-containing layer (that is, the image forming layer) in the present invention is preferably formed using a polymer latex as a binder. The amount of the binder in the organic silver salt-containing layer is such that the mass ratio of total binder / organic silver salt is 1 /
The range is preferably 10 to 10/1, more preferably 1/5 to 4/1.

The organic silver salt-containing layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide, which is a photosensitive silver salt. / Mass ratio of silver halide is preferably in the range of 400 to 5, more preferably 200 to 10.

The total amount of the binder in the image forming layer in the invention is preferably in the range of 0.2 to 30 g / m ² , more preferably in the range of 1 to 15 g / m ² . A crosslinking agent for crosslinking and a surfactant for improving coating properties may be added to the image forming layer of the invention.

The non-photosensitive organic silver salt which can be used in the present invention is relatively stable to light, but can be used in the presence of an exposed photocatalyst (such as a latent image of a photosensitive silver halide) and a reducing agent. Is a silver salt that forms a silver image when heated to 80 ° C. or higher. The organic silver salt can be any organic substance including a source capable of reducing silver ions. Such non-photosensitive organic silver salts are disclosed in JP-A-10-6289.
No. 9, paragraphs [0048] to [0049], EP No. 0803764A1, page 18, line 24 to page 19, line 37, European Patent Publication EP
No. 0962812 A1. Silver salts of organic acids, in particular (10 to 30 carbon atoms, preferably 15 to
Silver salts of 28) long chain aliphatic carboxylic acids are preferred. Preferred examples of the organic silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and mixtures thereof. In the present invention, among these organic silver salts, it is preferable to use an organic silver salt having a silver behenate content of 75 mol% or more.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be needle-like, rod-like, plate-like, or flake-like. In the present invention, it is preferable to use scaly organic silver salts. In the present specification, the flaky organic silver salt is defined as follows. The silver salt of the organic acid was observed with an electron microscope, and the shape of the silver salt of the organic acid was approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped were designated as a, b, and c from the shortest side (c is the same as b. Then, calculation is performed using the shorter numerical values a and b, and x is obtained as follows. x = b / a

In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, those satisfying the relationship of x (average) ≧ 1.5 are regarded as scaly. Preferably 30 ≧ x (average) ≧ 1.5, more preferably 2
0 ≧ x (average) ≧ 2.0. By the way, needle shape is 1 ≦ x
(Average) <1.5.

In the scaly particles, a can be regarded as the thickness of tabular particles having a main plane with b and c as sides. The average of a is preferably 0.01 μm to 0.23 μm, more preferably 0.1 μm to 0.20 μm. The average of c / b is preferably 1 to 6, more preferably 1.05 to
4, more preferably 1.1 to 3, particularly preferably 1.
1-2.

The particle size distribution of the organic silver salt is preferably monodispersed. The monodispersion is preferably 100% or less, more preferably 80% or less, and still more preferably 50% of the value obtained by dividing the standard deviation of the length of each of the minor axis and major axis by the minor axis and major axis, respectively. It is as follows. The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion. Another method for measuring monodispersity is to determine the standard deviation of the volume-weighted average diameter of the organic silver salt, and the percentage (coefficient of variation) divided by the volume-weighted average diameter is preferably 100% or less, It is preferably at most 80%, more preferably at most 50%. As a measurement method, for example, the organic silver salt dispersed in a liquid is irradiated with laser light, and the particle size (volume weighted average diameter) obtained by obtaining an autocorrelation function with respect to a time change of fluctuation of the scattered light is obtained. Can be.

Known methods can be applied to the production of the organic acid silver used in the present invention and its dispersion method. For example, the above-mentioned Japanese Patent Application Laid-Open No. 10-62899, European Patent Publication EP0803763A1, and European Patent Publication EP9
No. 62812A1 can be referred to.

In addition, when a photosensitive silver salt is allowed to coexist at the time of dispersing the organic silver salt, fog increases and the sensitivity is remarkably lowered. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. In the present invention, the amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is 0.1 mol% or less based on 1 mol of the organic acid silver salt in the liquid, and the photosensitive silver salt is positively added. Not something.

In the present invention, a heat-developable image recording material can be produced by mixing an aqueous dispersion of an organic silver salt and an aqueous dispersion of a photosensitive silver salt. The ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 to 30 mol%, more preferably 3 to 2 mol%.
A range of 0 mol%, especially 5 to 15 mol% is preferred. Mixing two or more aqueous dispersions of organic silver salts with two or more aqueous dispersions of photosensitive silver salts during mixing is a method preferably used for adjusting photographic characteristics.

[0168] While the organic silver salt can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably from 1 to 3 g / m ^2.

The photothermographic material of the present invention contains a reducing agent for silver ions. A reducing agent for silver ions is any substance (preferably an organic substance) that reduces silver ions to metallic silver.
It may be. Such a reducing agent is disclosed in JP-A-11-65.
No. 021, paragraph numbers [0043] to [0045]
And page 7, line 34 to page 18, line 12 of European Patent Publication EP 0803764A1.

In the present invention, it is preferable to use a bisphenol-based reducing agent as the reducing agent, and it is particularly preferable to use a compound represented by the following formula (I).

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In the general formula (I), R ¹ and R ¹ ′ each independently represent an alkyl group. R ² and R ² ′ each independently represent a hydrogen atom or a substituent that can be substituted on a benzene ring. X and X ^′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. R ¹ and X, ^{'and X'} R ^1, R
² and X, and R ^{2 ′} and X ^′ may combine with each other to form a ring. L is -S- group or -CH ³ - represents a group. R ³
Represents a hydrogen atom or an alkyl group.

In the general formula (I), R ¹ and R ^{1 ′} are each independently a substituted or unsubstituted, linear, branched or cyclic alkyl group. The alkyl group has 1 to 2 carbon atoms.
0 is preferred. The substituent of the alkyl group is not particularly limited, but is preferably an aryl group, a hydroxy group,
Examples include an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, an acyl group, a carbamoyl group, an ester group, and a halogen atom.

R ¹ and R ^{1 ′} are more preferably a secondary or tertiary alkyl group having 3 to 15 carbon atoms, specifically, isopropyl, isobutyl, tert-butyl, and tert-amyl groups. Tert-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like. More preferred are tertiary alkyl groups having 4 to 12 carbon atoms, among which tert-butyl, tert-amyl and 1-methylcyclohexyl are particularly preferred, and tert-butyl is most preferred.

R ² and R ^{2 ′} each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. X and X
^' Independently represents a hydrogen atom or a group that can be substituted on a benzene ring. As a group that can be substituted on the benzene ring,
Preferably, an alkyl group, an aryl group, a halogen atom, an alkoxy group, an acylamino group and the like are mentioned.

R ² and R ^{2 ′} preferably have 1 to 1 carbon atoms.
20 alkyl groups, specifically, methyl, ethyl, propyl, butyl, isopropyl, tert
-Butyl group, tert-amyl group, cyclohexyl group,
Examples thereof include a 1-methylcyclohexyl group, a benzyl group, a methoxymethyl group, and a methoxyethyl group. More preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group and a tert-butyl group.

X and X ^' are preferably a hydrogen atom, a halogen atom or an alkyl group, and particularly preferably a hydrogen atom. R ¹ and X, R ^{1 ′} and X ^′ , R ² and X, and R ^{2 ′} and X ^′ may be bonded to each other to form a ring. This ring is preferably a 5- to 7-membered ring, more preferably a saturated 6-membered ring.

L represents a —S— group or a —CHR ³ — group. L is preferably a -CHR ³ - is a group. R ³ is a hydrogen atom or an alkyl group. The alkyl group represented by R ³ may be linear, branched, or cyclic, and may be substituted. The alkyl group represented by R ³ preferably has 1 to 20 carbon atoms, more preferably 1 carbon atom.
~ 15. Specific examples of an unsubstituted alkyl group include
Examples include a methyl group, an ethyl group, a propyl group, a butyl group, a heptyl group, an undecyl group, an isopropyl group, a 1-ethylpentyl group, and a 2,4,4-trimethylpentyl group. Examples of the substituent of the alkyl group include a halogen atom, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, an oxycarbonyl group, a carbamoyl group, and a sulfamoyl group. . Preferred as R ³ are a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a 2,4,4-trimethylpentyl group. Particularly preferred as R ³ is a hydrogen atom, a methyl group, an ethyl group or a propyl group.

When R ³ is a hydrogen atom, R ² and R ² ′ are preferably an alkyl group having 2 to 5 carbon atoms,
An ethyl group and a propyl group are more preferred, and an ethyl group is most preferred. When R ³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, R ² and R ² ′ are preferably methyl groups. As the primary or secondary alkyl group having 1 to 8 carbon atoms that R ³ can have, a methyl group, an ethyl group, a propyl group, and an isopropyl group are more preferable, and a methyl group,
Ethyl and propyl groups are more preferred.

Among the compounds represented by formula (I), particularly preferred compounds are those in which R ¹ and R ¹ ′ are each independently a secondary or tertiary alkyl group, and R ² and R ² ′ are each independently an alkyl group. A compound wherein R ³ is a hydrogen atom or an alkyl group, and X and X ′ are both hydrogen atoms;
R ¹ and R ¹ 'is a tertiary alkyl group, R ² and R ^2' is an alkyl group, and R ³ is a hydrogen atom or an alkyl group; Among them, R ¹ and R ¹ 'is tertiary alkyl radical, R ^Two
And R ² ′ is an alkyl group having 2 or more carbon atoms, and R ³ is a hydrogen atom.

Specific examples of the compound represented by formula (I) are shown below, but the compounds usable in the present invention are not limited to these.

[0181]

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[0182]

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[0183]

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[0184]

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[0185]

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In the present invention, the amount of the reducing agent added is 0.01
To 5.0 g / m ² , preferably 0.1 to 3.0 g / m ² .
The content is more preferably 0 g / m ² , and is preferably contained in an amount of 5 to 50% by mole, more preferably 10 to 40% by mole, per mole of silver on the surface having the image forming layer. The reducing agent is preferably contained in the image forming layer.

The reducing agent may be contained in the coating liquid by any method such as a solution form, an emulsified dispersion form, and a solid fine particle dispersion form, and may be contained in the photothermographic material. Well-known emulsification dispersion methods include oils such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, and dissolution using an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. There is a method of manufacturing.

In the solid fine particle dispersion method, a powder of a reducing agent is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill or ultrasonic waves to obtain a solid dispersion. Is prepared. In this case, a protective colloid (for example, polyvinyl alcohol) and a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. The aqueous dispersion can contain a preservative (eg, benzoisothiazolinone sodium salt).

A crosslinking agent for crosslinking and a surfactant for improving coating properties may be added to the image forming layer.

The antifoggants, stabilizers and stabilizer precursors which can be used in the present invention are described in JP-A-10-6.
No. 20070, paragraph [0070], page 20 line 57 of EP 0803764A1.
What is described on page 21, line 7 is mentioned. The antifoggant preferably used in the present invention is an organic halide, which is disclosed in JP-A-11-65021.
Japanese Patent Application Publication No. JP-A-2006-115122, paragraphs [0111] to [0112]. In particular, Japanese Patent Application No. 11-8729.
7, an organic halogen compound represented by the formula (P),
Organic polyhalogen compounds represented by the general formula (II) of JP-A-10-339934 are preferred.

Hereinafter, preferred organic polyhalogen compounds in the present invention will be described in detail. Preferred polyhalogen compounds are compounds represented by the following general formula (III). General formula (III): Q- (Y) nC (Z ¹ ) (Z ² ) X In general formula (III), Q represents an alkyl group, an aryl group or a heterocyclic group which may have a substituent. Represents
Y represents a divalent linking group, n represents 0 or 1, Z ¹
And Z ² represent a halogen atom, and X represents a hydrogen atom or an electron-withdrawing group.

The alkyl group represented by Q in formula (III) is a linear, branched or cyclic alkyl group,
Preferably 1 to 20 carbon atoms, more preferably 1 to 12,
Particularly preferably, it is 1 to 6. For example, methyl, ethyl, allyl, n-propyl, iso-propyl, sec
-Butyl, iso-butyl, tert-butyl, sec
-Pentyl, iso-pentyl, tert-pentyl,
tert-octyl, 1-methylcyclohexyl and the like. Preferably it is a tertiary alkyl group.

The alkyl group represented by Q may have a substituent, and any substituent may be used as long as it does not adversely affect photographic performance. Examples of the substituent include a halogen atom (fluorine atom). Atom, chloro atom, bromine atom or iodine atom), alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group (including N-substituted nitrogen-containing heterocyclic group, for example, morpholino group), alkoxycarbonyl group, Aryloxycarbonyl group, carbamoyl group, imino group, imino group substituted with N atom, thiocarbonyl group, carbazoyl group, cyano group, thiocarbamoyl group, alkoxy group, aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy Or aryloxy) carbonyloxy group, sulfonyloxy group, acylamide group, Ruhon'amido group, a ureido group,
Thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, (alkyl or aryl) sulfonyluureido group, nitro group, (alkyl or aryl) sulfonyl group, sulfamoyl Group, a group containing a phosphate amide or a phosphate ester structure, a silyl group, a carboxyl group or a salt thereof,
Examples thereof include a sulfo group or a salt thereof, a phosphate group, a hydroxy group, and a quaternary ammonium group. These substituents may be further substituted with these substituents.

The aryl group represented by Q in formula (III) is a monocyclic or condensed-ring aryl group, preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 10 carbon atoms. , A phenyl group or a naphthyl group is preferred. The aryl group represented by Q may have a substituent, and any substituent may be used as long as it does not adversely affect photographic performance. And the same groups as mentioned above.
Particularly preferred is a case where Q is a phenyl group substituted with an electron-withdrawing group having a Hammett's σp having a positive value. The electron withdrawing group σp value is preferably in the range of 0.2 to 2.0, and more preferably in the range of 0.4 to 1.0. Specifically, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group,
Examples include an alkylsulfonyl group, an arylsulfonyl group, an alkylphosphoryl group, a sulfoxide group, an acyl group, a heterocyclic group, a halogen atom, a halogenated alkyl group, and a phosphoryl group. More preferred electron-withdrawing groups are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, and an alkylphosphoryl group, among which a carbamoyl group is most preferred.

The heterocyclic group represented by Q in formula (III) includes a 5- or 7-membered saturated or unsaturated heterocyclic ring containing at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur atoms. Those which are monocyclic or fused rings are preferred. Examples of heterocycles are preferably pyridine, quinoline, isoquinoline, pyrimidine, pyrazine, pyridazine, phthalazine, triazine, furan, thiophene, pyrrole, oxazole, benzoxazole, thiazole, benzothiazole, imidazole, benzimidazole, thiadiazole, triazole and the like. And more preferably pyridine, quinoline, pyrimidine, thiadiazole and benzothiazole, and particularly preferably pyridine, quinoline and pyrimidine. The heterocyclic group represented by Q may have a substituent, and examples thereof include the same groups as the substituents of the alkyl group represented by Q.

Particularly preferred as Q is a phenyl group substituted with an electron-withdrawing group having a positive Hammett's σp. As a substituent of Q, it may have a ballast group used in a photographic material to reduce diffusivity, an adsorptive group to a silver salt, or a group imparting water solubility, or polymerize with each other to form a polymer. Or the substituents may be bonded to each other to form a bis-type, tris-type, or tetrakis-type.

In the general formula (III), Y represents a divalent linking group, preferably -SO _2- , -SO-, -C
An O-, particularly preferably -SO ₂ - is. In the general formula (III), n represents 0 or 1, but preferably 1. Z ¹ and Z ² each independently represent a halogen atom (eg, fluorine, chlorine, bromine, iodine, etc.), but it is most preferred that both Z ¹ and Z ² are bromine atoms. X represents a hydrogen atom or an electron-withdrawing group.
The electron withdrawing group represented by X is a Hammett's substituent constant σ
_p is a substituent that can take a positive value, specifically, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a halogen atom,
Examples include an acyl group and a heterocyclic group. X is preferably a hydrogen atom or a halogen atom, and most preferably a bromine atom.

Examples of the polyhalogen compound of the general formula (III) include, for example, US Pat. No. 3,874,946, US Pat. No. 4,756,999, and US Pat. No. 5,340,712. U.S. Patent No. 5,36
No. 9,000, U.S. Pat. No. 5,464,737, JP-A-50-137126, and JP-A-50-837.
Nos. 9020, 50-119624, 59
-57234, JP-A-7-2781, 7
Nos. 5621, 9160160164 and 10
JP-197988, JP-A-9-244177, JP-A-9-244178, JP-A-9-160167,
JP-A-9-319022, JP-A-9-258367, JP-A-9-265150, JP-A-9-319022, JP-A-10-197989, and JP-A-11-2423
04, Japanese Patent Application No. 10-181449, 10
Compounds described in JP-A-292864, JP-A-11-90095, JP-A-11-89773, JP-A-11-205330 and the like can be mentioned. The general formula (I)
Specific examples of the polyhalogen compound represented by II) are shown below, but the compounds that can be used in the present invention are not limited thereto.

[0199]

Embedded image

[0200]

Embedded image

[0201]

Embedded image

The polyhalogen compounds represented by the general formula (III) may be used alone or in combination of two or more.
The compound represented by the formula (III) is preferably used in an amount of 10 ^-4 to 1 mol, more preferably 10 ^{-3 to} 0.8 mol, per 1 mol of the non-photosensitive silver salt in the image forming layer. And more preferably in the range of 5 × 10 ^{−3 to} 0.5 mol. In the present invention, as a method for incorporating the antifoggant into the photothermographic material, the method described in the above-mentioned method for containing a reducing agent can be mentioned, and the organic polyhalogen compound is preferably added in the form of a solid fine particle dispersion.

Other antifoggants are described in
No.-65021, paragraph [0113], mercury (I
I) salts, benzoic acids of the same publication paragraph number [0114],
A salicylic acid derivative represented by the formula (Z) in Japanese Patent Application No. 11-87297, a formalin scavenger compound represented by the formula (S) in Japanese Patent Application No. 11-23995,
The triazine compound according to claim 9 of JP-A-11-352624, the compound represented by the general formula (III) of JP-A-6-11791, 4-hydroxy-6-methyl-1,3,3a, 7 -Tetrazaindene and the like.

The photothermographic material of the present invention may contain an azolium salt for the purpose of preventing fog. Examples of the azolium salt include compounds represented by the general formula (XI) described in JP-A-59-193449, and JP-B-55-12581.
And the compound represented by formula (II) described in JP-A-60-153039.
The azolium salt may be added to any part of the heat-developable image recording material, but it is preferable to add the azolium salt to the layer having the image forming layer, more preferably to the organic silver salt-containing layer. . The azolium salt may be added at any time during the preparation of the coating solution, and when the azolium salt is added to the organic silver salt-containing layer, may be at any stage during the preparation of the coating solution from the preparation of the organic silver salt, but after the preparation of the organic silver salt. To just before application. The azolium salt may be added by any method such as powder, solution, and fine particle dispersion. Further, it may be added as a solution mixed with other additives such as a sensitizing dye, a reducing agent, and a color tone agent. In the present invention, the addition amount of the azolium salt may be any amount, but is preferably 1 × 10 ⁻⁶ mol to 2 mol per 1 mol of silver, and
The amount is more preferably from 10 ^-3 mol to 0.5 mol.

In the present invention, in order to control development by suppressing or accelerating development, and to improve spectral sensitization efficiency,
A mercapto compound, a disulfide compound, and a thione compound can be contained for the purpose of improving the storage stability before and after development, for example. 18
No. 6572, compounds represented by formula (I) and specific examples thereof include paragraphs [0033] to [0052],
European Patent Publication EP 0803764A1 No. 20
Pages 36 to 56, and those described in Japanese Patent Application No. 11-273670 can be used. Among them, mercapto-substituted heteroaromatic compounds are preferred.

In the photothermographic material of the present invention, a toning agent is preferably added, and the toning agent is described in JP-A-10-6289.
No. 9, Paragraph Nos. [0054] to [0055], European Patent Publication No. EP 0803764A1, page 21, lines 23 to 48, and JP-A-2000-35631. Particularly, phthalazinones ( Phthalazinone, phthalazinone derivative or metal salt;
(1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (for example, phthalic acid, 4- Combination with methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride); phthalazines (phthalazine, phthalazine derivative or metal salt; for example, 4- (1-naphthyl)
Phthalazine, 6-isopropylphthalazine, 6-ter
t-butylfuratazine, 6-chlorophthalazine, 5,7
-Dimethoxyphthalazine and 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferred, and a combination of phthalazines and phthalic acids is particularly preferred.

The plasticizers and lubricants that can be used in the image forming layer are described in JP-A No. 11-65021, paragraph [0117]. JP-A-11-223898, paragraphs [0136] to [0193], Japanese Patent Application No. 11-8729.
No. 7, the formula (H), the formulas (1) to (3), the formula (A),
Compound (B), compounds of the general formulas (III) to (V) described in Japanese Patent Application No. 11-91652 (specific compounds:
Chemical formulas 21 to 24) and a contrast enhancement accelerator are disclosed in
-65021, paragraph [0102],
No. 223898, paragraph numbers [0194] to [019]
5].

In order to use formic acid or formate as a strong fogging substance, the side having the image-forming layer containing the photosensitive silver halide is preferably 5 mmol or less, more preferably 1 mol / mol silver.
It is preferable to contain it in an amount of not more than mmol.

When a super-high contrast agent is used in the photothermographic material of the present invention, it is preferable to use an acid or a salt thereof formed by hydration of diphosphorus pentoxide in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametaline Acid (salt)
And the like. Particularly preferred acids or salts thereof formed by hydration of diphosphorus pentoxide include:
Orthophosphoric acid (salt) and hexametaphosphoric acid (salt) can be mentioned. Specific salts include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate. The amount of phosphorus pentoxide hydrated acid or salt thereof and (coating amount per heat developable image recording material 1 m ²⁾ may be a desired amount depending on the performance such as sensitivity and fog, but
0.1-500 mg / m ² is preferable, and 0.5-100
mg / m ² is more preferred.

The photothermographic material according to the invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer or a plurality of layers. Regarding the surface protective layer, see JP-A-11-650.
No. 21, paragraphs [0119] to [0120]. Gelatin is preferred as the binder for the surface protective layer, but polyvinyl alcohol (PVA) is also preferred. As gelatin, inert gelatin (for example, Nitta Gelatin 750), phthalated gelatin (for example, Nitta Gelatin 801) and the like can be used.
As PVA, PVA-105 of completely saponified product, PVA-205 and PVA-335 of partially saponified product, MP-203 of modified polyvinyl alcohol (Kuraray Co., Ltd.)
Trade name). Protective layer (per layer)
Amount of polyvinyl alcohol applied (per 1 m ^{2 of} support)
Is preferably 0.3 to 4.0 g / m ^{2, and} 0.3 to 4.0 g / m ^2.
2.0 g / m ² is more preferred.

In particular, when the photothermographic material of the present invention is used for printing in which dimensional change is a problem, it is preferable to use a polymer latex for the surface protective layer and the back layer.
For such polymer latexes, see "Synthetic Resin Emulsion (edited by Tadashi Okuda and Hiroshi Inagaki, published by Polymer Publishing Association (1978))", "Application of Synthetic Latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, edited by Keiji Kasahara) Molecular publishing society (1993)), "Synthesis of synthetic latex (Souichi Muroi, published by Kobunshi Kankokai (1970))" and the like, and specifically, methyl methacrylate (33.5% by mass) / Latex of ethyl acrylate (50% by weight) / methacrylic acid (16.5% by weight), methyl methacrylate (47.5% by weight) / butadiene (4
Latex of 7.5% by mass) / itaconic acid (5% by mass) copolymer, latex of ethyl acrylate / methacrylic acid copolymer, methyl methacrylate (58.9%)
Mass%) / 2-ethylhexyl acrylate (25.4
Mass%) / styrene (8.6 mass%) / 2-hydroxyethyl methacrylate (5.1 mass%) / latex of acrylic acid (2.0 mass%) copolymer, methyl methacrylate (64.0 mass%) / styrene Latex of (9.0% by mass) / butyl acrylate (20.0% by mass) / 2-hydroxyethyl methacrylate (5.0% by mass) / acrylic acid (2.0% by mass). Further, as a binder for the surface protective layer, a combination of a polymer latex described in Japanese Patent Application No. 11-6872, a technique described in paragraphs [0021] to [0025] of Japanese Patent Application No. 11-143058, etc. Paragraph Nos. [0027] to No. 11-6872 of the specification
Technology described in [0028], JP-A-2000-19678
The technology described in Paragraph Nos. [0023] to [0041] of Japanese Patent Application Laid-Open Publication No. H10-26095 may be applied. The ratio of the polymer latex in the surface protective layer is preferably from 10% by mass to 90% by mass, particularly preferably from 20% by mass to 80% by mass of the total binder. Coating amount of all binders (including water-soluble polymer and latex polymer) of surface protective layer (per layer) (support 1 m ²
(Per) is preferably 0.3 to 5.0 g / m ² ,
0.3-2.0 g / m < ² > is more preferable.

The preparation temperature of the coating solution for the image forming layer is from 30 ° C. to 6 ° C.
5 ° C. is preferred, a more preferred temperature is 35 ° C. to less than 60 ° C., and a more preferred temperature is 35 ° C. to 55 ° C. Also,
The temperature of the coating solution for the image forming layer immediately after the addition of the polymer latex is preferably maintained at 30 ° C to 65 ° C. Also,
It is preferable that the reducing agent and the organic silver salt are mixed before the addition of the polymer latex.

The image forming layer is composed of one or more layers on a support. Organic silver salt when composed of one layer,
It consists of a photosensitive silver halide, a reducing agent and a binder, and optionally contains additional materials such as toning agents, coating auxiliaries and other auxiliaries. When it is composed of two or more layers, the first image-forming layer (usually a layer adjacent to the support) contains an organic silver salt and a photosensitive silver halide, and the second image-forming layer or both layers contain some. Other components must be included. The construction of a multicolor light-sensitive photothermographic material may include a combination of these two layers for each color, or all in a single layer as described in US Pat. No. 4,708,928. May be included. In the case of a multi-dye, multi-color photothermographic material, each emulsion layer is generally functionalized or non-functional between the light-sensitive layers, as described in U.S. Pat. No. 4,460,681. By using a functional barrier layer, they are kept distinct from each other.

In the image forming layer (photosensitive layer), various dyes and pigments (for example, CI Pig) are used from the viewpoints of color tone improvement, interference fringe generation during laser exposure, and irradiation prevention.
ment Blue 60, C.I. I. Pigment
Blue 64, C.I. I. Pigment Blue
15: 6) can be used. These are described in International Publication WO 98/36322, Japanese Patent Laid-Open No. 10-26.
Nos. 8465, 11-338098 and the like.

In the photothermographic material of the present invention, an antihalation layer can be provided on the side farther from the light source than the image forming layer.

The photothermographic material generally has a non-photosensitive layer in addition to the photosensitive layer. The non-photosensitive layer may be arranged as follows: (1) a protective layer provided on the photosensitive layer (on the side farther than the support); (2) between a plurality of photosensitive layers or between the photosensitive layer and the protective layer (3) an undercoat layer provided between the photosensitive layer and the support, and (4) a back layer provided on the opposite side of the photosensitive layer. The filter layer is
The layer (1) or (2) is provided on the heat-developable image recording material. The antihalation layer is provided on the heat-developable image recording material as the layer (3) or (4).

The antihalation layer is disclosed in
No. 1-65021, paragraph numbers [0123] to [012]
4], JP-A-11-223898 and 9-230
Nos. 531 and 10-36695 and 10-1
04779, 11-231457 and 1
It is described in JP-A-1-352625, JP-A-11-352626 and the like. The antihalation layer contains an antihalation dye having absorption at the exposure wavelength. When the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable. When using a dye having absorption in the visible region to prevent halation, it is preferable that substantially no color of the dye remains after image formation, and a means for decoloring by the heat of heat development is used. It is particularly preferable to add a thermal decoloring dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These techniques are described in JP-A-11-231457.
No., etc.

The addition amount of the decolorizable dye is determined depending on the use of the dye. Generally, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably from 0.2 to 2. The amount of the dye used to obtain such an optical density is generally 0.00
It is about 1 to 1 g / m ² .

When the dye is decolored in this manner, the optical density after thermal development can be reduced to 0.1 or less. Two or more decolorizable dyes may be used in combination in a heat-decolorable recording material or a photothermographic material. Similarly, two or more base precursors may be used in combination. In thermal decoloring using such a decoloring dye and a base precursor,
When mixed with a base precursor as described in JP-A-11-352626, a substance (for example, diphenylsulfone, 4-chlorophenyl (phenyl) sulfone) which lowers the melting point by 3 ° C. or more can be used in combination with heat discoloration. It is preferred in that respect.

In the present invention, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver tone and the temporal change of the image. Such colorants are described in JP-A-62-210458 and 63-104.
No. 046, 63-103235, 63-103
JP-A-208846, JP-A-63-306436, JP-A-63-314535, JP-A-01-61745, Japanese Patent Application No. 11-276675, and the like. Such a colorant is usually 0.1 mg / m
It is added in the range of ^{2 to 1} g / m ² , and the layer to be added is preferably a back layer provided on the opposite side of the image forming layer.

The photothermographic material of the present invention is a so-called single-sided light-sensitive material having at least one image forming layer containing a silver halide emulsion on one side of a support and a back layer on the other side. Preferably, there is.

In the present invention, it is preferable to add a matting agent for improving transportability.
JP-A-11-65021, paragraph number [0126]-
[0127]. The matting agent is preferably from 1 to 400 mg / m ² , more preferably from 5 to 300 m ² , when represented by the coating amount per m ² of the thermally developed image recording material.
g / m ² . The matte degree of the image forming surface may be any value as long as stardust failure does not occur, but the Beck smoothness is preferably 30 seconds to 2000 seconds, particularly 40 seconds to 1500.
Seconds are preferred. Beck smoothness is measured according to Japanese Industrial Standards (JI
S) It can be easily obtained by P8119 “Smoothness test method of paper and paperboard using Beck tester” and TAPPI standard method T479.

In the present invention, the matte degree of the back layer is preferably such that the Bekk smoothness is from 10 seconds to 1200 seconds.
Seconds to 800 seconds, more preferably 40 seconds to 5 seconds.
00 seconds.

In the present invention, the matting agent is preferably contained in the outermost surface layer of the heat-developable image recording material, a layer functioning as the outermost surface layer, or a layer near the outer surface, and acts as a so-called protective layer. It is preferably contained in a layer to be formed.

The back layer applicable to the present invention is described in JP-A-11-65021, paragraph [01].
28] to [0130].

The photothermographic material of the present invention preferably has a film surface pH before heat development of 6.0 or less, more preferably 5.5 or less. The lower limit is not particularly limited, but is about 3. For adjusting the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a nonvolatile acid such as sulfuric acid, or a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is preferable in achieving a low film surface pH since ammonia is easily volatilized and can be removed before the application step and the heat development. The method of measuring the film surface pH is described in paragraph [0123] of Japanese Patent Application No. 11-87297.

A hardener may be used for each layer such as the image forming layer, the protective layer and the back layer. Examples of hardeners include T.I.
H. James "THE THEORY OF T
HEPHOTOGRAPHIC PROCESS FO
URTH EDITION "(Macmillian
Publishing Co. , Inc. Published, 197
There are various methods described on pages 77 to 87, chromium alum, 2,4-dichloro-6-hydroxy-s-
Triazine sodium salt, N, N-ethylenebis (vinylsulfoneacetamide), N, N-propylenebis (vinylsulfoneacetamide), as well as polyvalent metal ions described on page 78 of the same book, US Pat. No. 4,281,060 And polyisocyanates such as JP-A-6-208193, epoxy compounds such as U.S. Pat. No. 4,791,042, and vinylsulfone compounds such as JP-A-62-89048 are preferably used. .

The hardener is added as a solution, and the time for adding this solution to the coating solution for the protective layer is from 180 minutes before coating.
Immediately before, preferably before 60 minutes to 10 seconds, there is no particular limitation on the mixing method and mixing conditions as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, there is a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time, Harnby, M .; F. Edwar
ds, A.D. W. There is a method using a static mixer or the like described in Chapter 8 of Nienow, "Liquid Mixing Technology" translated by Koji Takahashi (Nikkan Kogyo Shimbun, 1989).

The surfactant applicable to the present invention is described in JP-A-11-65021, paragraph [0132],
Paragraph [0133] of the same publication for the solvent, paragraph [0134] of the same publication for the support, paragraph [0135] of the same publication for the antistatic or conductive layer, and the same publication for the method of obtaining a color image. Publication paragraph number [01
36], paragraphs [0061] to [0064] of JP-A No. 11-84573 and JP-A No. 11-84573.
No. 106881 Paragraph Nos. [0049] to [00]
62] has been described.

The transparent support is a polyester which has been subjected to a heat treatment at a temperature in the range of 130 to 185 ° C. in order to alleviate the internal strain remaining in the film at the time of biaxial stretching and to eliminate the heat shrinkage distortion generated during the heat development processing. Particularly, polyethylene terephthalate is preferably used. In the case of a photothermographic material for medical use, the transparent support is made of a blue dye (for example,
It may be colored with dye-1) described in Examples of JP-A-240877, or may be uncolored. As the support, water-soluble polyester disclosed in JP-A-11-84574,
Styrene-butadiene copolymer disclosed in JP-A-186565, paragraph No. [00] of Japanese Patent Application No. 11-106881.
It is preferable to apply an undercoating technique such as a vinylidene chloride copolymer of [63] to [0080]. Further, regarding the antistatic layer or the undercoat, JP-A-56-143430, JP-A-56-143431, and JP-A-58-6264.
6, JP-A-56-120519, JP-A-11-
No. 84573, paragraphs [0040] to [005]
1], U.S. Pat. No. 5,575,957, paragraphs [0078] to [0078] of JP-A-11-223898.
The technique described in [0084] can be applied.

The photothermographic material is preferably of a monosheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material).

The photothermographic material may further contain an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid. Various additives are added to either the photosensitive layer or the non-photosensitive layer. Regarding them, International Publication WO98 / 36322, European Patent Publication EP8
JP-A Nos. 037664A1, 10-186567 and 10-18568 can be referred to.

The photothermographic material of the present invention may be applied by any method. Specifically, extrusion coating, slide coating, curtain coating, dip coating, knife coating,
Flow coating or US Pat. No. 2,681,2
Various coating operations are used, including extrusion coating using a hopper of the type described in U.S. Pat.
tephen F. Kistler, Peter M.
"LIQUID FILM C" by Schweizer
OATING "(published by CHAPMAN & HALL,
(1997) pages 399 to 536, extrusion coating or slide coating is preferably used, and slide coating is particularly preferably used. An example of the shape of a slide coater used for slide coating is shown in FIG.
1b. In one. Also, if desired, pp. 399-53 of the same book.
Two or more layers can be coated simultaneously by the method described on page 6, the method described in U.S. Pat. No. 2,761,791 and British Patent No. 837,095.

The coating solution for the organic silver salt-containing layer in the present invention comprises:
It is preferably a so-called thixotropic fluid. The thixotropic property refers to a property in which the viscosity decreases as the shear rate increases. Although any apparatus may be used for the viscosity measurement, an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is preferably used, and the viscosity is measured at 25 ° C. Here, the viscosity of the coating solution for the organic silver salt-containing layer in the present invention at a shear rate of 0.1 S ^-1 is preferably from 400 mPa · s to 100,000 mPa · s, more preferably from 500 mPa · s to 20,000.
mPa · s. Further, at a shear rate of 1000 S ⁻¹ , the pressure is preferably 1 mPa · s to 200 mPa · s, more preferably 5 mPa · s to 80 mPa · s.

Various systems expressing thixotropy are known, and are described in “Lecture / Rheology”, edited by Polymer Publishing Association, Muroi,
It is described in Morino co-author, “Polymer Latex” (published by the Society of Polymer Publishing). In order for a fluid to exhibit thixotropic properties, it is necessary to contain a large amount of solid fine particles.
In order to enhance the thixotropic property, it is effective to include a thickened linear polymer, to increase the aspect ratio of the contained solid fine particles in an anisotropic shape, to use an alkali thickener, and to use a surfactant.

Techniques that can be used for the photothermographic material of the present invention include those described in European Patent Publication EP803376A1.
Patent Publication, European Patent Publication EP 883022 A1, International Publication WO 98/36322, JP-A-56-62.
648, 58-62644, and JP-A-9-628.
Nos. 281637 and 9-297367, 9-30
No. 4869, No. 9-31405, No. 9-3
29865, 10-10669, 10
-62899, 10-69023, 1
Nos. 0-186568 and 10-90823,
Nos. 10-171063, 10-186565, 10-186567, and 10-1865
No. 69-No. 10-186572, No. 10-1
No. 97974, No. 10-197982, No. 1
Nos. 0-197983, 10-197985 to 10-197987, and 10-207001
JP-A-10-207004 and JP-A-10-207004
807, 10-282601, 10-
No. 288823, No. 10-288824, No. 10-307365, No. 10-312038, No. 10-339934, No. 11-7100, No. 11-15105, No. 11-24200
Gazette, JP-A-11-24201 and JP-A-11-3083
No. 2, No. 11-84574, No. 11-650
JP-A-21, JP-A-11-109547 and JP-A-11-1
No. 25880, No. 11-129629, No. 1
1-1133536-11-133538, 11-133542, 11-13354
No. 3, No. 11-223898, No. 11-35
No. 2627 is also cited.

The photothermographic material of the present invention may be developed by any method. Generally, the photothermographic material exposed imagewise is heated to develop. The preferred development temperature is 80 to 250 ° C, more preferably 100 to 250 ° C.
140 ° C. The development time is preferably from 2 to 30 seconds, more preferably from 5 to 19 seconds, and particularly preferably from 5 to 16 seconds.

As a method of thermal development, a plate heater method is preferable. The heat development method using a plate heater method is preferably a method described in JP-A-11-133572, and a visible image is obtained by bringing the heat-developable photosensitive material having a latent image formed thereon into contact with a heating means in a heat development section. A heat developing device, wherein the heating means comprises a plate heater,
A plurality of pressing rollers are provided to face each other along one surface of the plate heater, and the photothermographic material is passed between the pressing roller and the plate heater to perform thermal development. This is a heat developing device. The plate heater is divided into 2 to 6 stages, and the tip is 1 to 10 ° C.
It is preferable to lower the temperature. Such a method is also described in JP-A-54-30032, which makes it possible to exclude water and an organic solvent contained in a photothermographic material from the system, The change in the shape of the support of the photothermographic material due to the heating of the material can also be suppressed.

The heat-developable image recording material of the present invention may be exposed by any method, but a laser beam is preferred as an exposure light source. As the laser beam according to the present invention, a gas laser (Ar ⁺ , He—Ne), a YAG laser, a dye laser, a semiconductor laser, or the like is preferable. Further, a semiconductor laser and a second harmonic generation element can be used. Preferably, a gas or semiconductor laser emitting red to infrared light is used.

As a medical laser imager having an exposure section and a heat development section, Fuji Medical Dry Laser Imager FM-DPL can be mentioned.
Regarding FM-DP L, Fuji Medical
Review No. 8, pages 39 to 55, and it goes without saying that those techniques are applied as a laser imager for the photothermographic material of the present invention. In addition, Fuji Medical Systems proposed "A" as a network system conforming to the DICOM standard.
It can also be applied as a photothermographic material for a laser imager in "D network".

The photothermographic material of the present invention forms a black-and-white image by a silver image, and is used for medical diagnosis, photothermographic material for industrial photography, photothermographic material for printing, COM
Is preferably used as a photothermographic material.

[0242]

The features of the present invention will be described more specifically with reference to the following examples. Material, amount used in the following examples,
The ratio, processing content, processing procedure, and the like can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples described below.

Example 1 << Preparation of Undercoated Support >> (Preparation of PET Support) Using terephthalic acid and ethylene glycol, the intrinsic viscosity IV = 0.66 (phenol / tetrachloroethane) according to a conventional method. = 25 in 6/4 (mass ratio)
(Measured in ° C.). After pelletizing this 1
It was dried at 30 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and quenched to prepare an unstretched film having a thickness of 175 μm after heat setting. This was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then transversely stretched 4.5 times using a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. After this, 240 ° C
After heat setting for 20 seconds, the film was relaxed 4% in the lateral direction at the same temperature. After slitting the chuck part of the tenter,
Knurling both ends, winding at 4kg / cm ²
A roll having a thickness of 175 μm was obtained.

(Surface Corona Treatment) Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, 0.375 kV was applied to the support.
-It turned out that the processing of A * minute / m < ² > was performed.
The processing frequency at this time is 9.6 kHz, and the electrode and the dielectric
The gap clearance of the shell was 1.6 mm.

(Preparation of Undercoating Support) (1) Preparation of Undercoating Layer Coating Formulation 1 (for the undercoating layer on the image forming layer side) 59 g of Pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd. Polyethylene glycol monononylphenyl ether (average ethylene oxide number = 8.5, 10% by mass solution) 5.4 g-Polymer fine particles 0.91 g (manufactured by Soken Chemical Co., Ltd., MP-1000, average particle size 0.4 m)-Distillation 935 ml of water

Formulation 2 (for the first layer on the back side) • 158 g of styrene-butadiene copolymer latex (solid content: 40% by mass, styrene / butadiene mass ratio = 68/32) • 2,4-dichloro-6-hydroxy- S-triazine sodium salt 20 g (8% by mass aqueous solution) ・ Sodium laurylbenzenesulfonate (1% by mass aqueous solution) 10 ml ・ Distilled water 854 ml

Formulation 3 (for the second layer on the back side) 84 g of SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion) ・ Gelatin (10 mass% aqueous solution) 2 g-Shin-Etsu Chemical Co., Ltd., Metroose TC-5 (2 mass% aqueous solution) 8.6 g-Soken Chemical Co., Ltd., MP-1000 0.01 g-Sodium dodecylbenzenesulfonate (1 mass% aqueous solution) 10 ml- NaOH (1% by mass) 6 ml ・ Proxel (manufactured by ICI) 1 ml ・ Distilled water 805 ml

(Preparation of undercoat support) The thickness of 175 μm
m of the biaxially stretched polyethylene terephthalate support was subjected to the above-mentioned corona discharge treatment, and then the undercoating coating liquid formulation 1 was coated on one side (image forming layer side) with a wire bar at a wet application amount of 6.6 ml / m ^2. (Per side) and dried at 180 ° C. for 5 minutes. Then, the undercoating liquid formulation 2 was applied to the back surface (back surface) with a wire bar so that the wet application amount was 5.7 ml / m ^2. And dried at 180 ° C. for 5 minutes. Further, the undercoating coating liquid formulation 3 was coated on the back surface (back surface) with a wire bar so that the wet coating amount was 7.7 ml / m ^2, and
After drying at 0 ° C. for 6 minutes, an undercoat support was prepared.

<< Preparation of Back Surface Coating Solution >> (Preparation of Solid Fine Particle Dispersion (a) of Base Precursor)
64 g of the base precursor compound 11, 28 g of diphenyl sulfone and a surfactant Demol N manufactured by Kao Corporation
10 g was mixed with 220 ml of distilled water, and the mixed solution was dispersed in beads using a sand mill (manufactured by Imex Co., Ltd., 1/4 Gallon sand grinder mill) to obtain a solid fine particle dispersion of a base precursor compound having an average particle diameter of 0.2 μm. (A) was obtained.

(Preparation of Dye Solid Fine Particle Dispersion) 9.6 g of cyanine dye compound 13 and 5.8 g of sodium p-dodecylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was subjected to sand mill (manufactured by Imex Co., Ltd.). 1
/ 4 Gallon sand grinder mill) to obtain a dispersion of fine solid dye particles having an average particle diameter of 0.2 µm.

(Preparation of antihalation layer coating solution) Gelatin 17 g, polyacrylamide 9.6 g, solid fine particle dispersion (a) of the above base precursor, 70 g, dye solid fine particle dispersion 56 g, monodispersed polymethyl methacrylate fine particles (average Particle size 8.0 μm, particle size standard deviation 0.4) 1.5 g, benzoisothiazolinone 0.03
g, 2.2 g of sodium polyethylene sulfonate, 0.2 g of blue dye compound 14, and 3 g of yellow dye compound 15.
9 g and 844 ml of water were mixed to prepare an antihalation layer coating solution.

(Preparation of Back Surface Protective Layer Coating Solution)
The mixture was kept at 0 ° C., and gelatin 50 g, polystyrene sodium sulfonate 0.2 g, N, N-ethylenebis (vinylsulfone acetamide) 2.4 g, tert-octylphenoxyethoxyethaneethane sodium 1 g,
Benzoisothiazolinone 30 mg, N-perfluorooctylsulfonyl-N-propylalanine potassium salt 3
7 mg, polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [average degree of polymerization of ethylene oxide 15]
0.15 g, C ₈ F ₁₇ SO ₃ K 32 mg, C ₈ F ₁₇ SO ₂ N
_{(C 3 H 7) (CH} 2 CH 2 O) 4 (CH 2) 4 SO 3 Na64
mg, acrylic acid / ethyl acrylate copolymer (copolymerization mass ratio 5/95) 8.8 g, Aerosol OT (manufactured by American Cyanamid Co.) 0.6 g, 1.8 g of liquid paraffin emulsion as liquid paraffin, 950 ml of water
This was mixed to give a coating liquid for the back surface protective layer.

<< Preparation of Silver Halide Emulsion A >> Distilled Water 14
To 21 ml, 3.1 ml of a 1% by mass potassium bromide solution was added, and 3.5 ml of 0.5 mol / L sulfuric acid was further added.
While stirring the solution to which 31.7 g of phthalated gelatin was added in a stainless steel reaction bottle, the solution temperature was maintained at 30 ° C., a solution A obtained by adding distilled water to 22.22 g of silver nitrate to 95.4 ml, and bromide were added. A solution B obtained by diluting potassium (15.3 g) and potassium iodide (0.8 g) to a volume of 97.4 ml with distilled water was added at a constant flow rate over 45 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous solution of hydrogen peroxide was added, and a 10% by mass aqueous solution of benzimidazole was further added to 1 ml.
0.8 ml was added. Further, a solution C obtained by adding 51.86 g of silver nitrate to 317.5 ml by adding distilled water and a solution D obtained by diluting 44.2 g of potassium bromide and 2.2 g of potassium iodide to a volume of 400 ml with distilled water were used. , Solution C was added at a constant flow rate over 20 minutes, and solution D was pAg
Was added by the controlled double jet method while maintaining at 8.1. The total amount of potassium hexachloride (III) acid salt was added 10 minutes after starting to add the solution C and the solution D so as to be 1 × 10 ⁻⁴ mol per mol of silver. Five seconds after the completion of the addition of the solution C, an aqueous solution of potassium hexairon cyanide (II) was added in an amount of 3 × 10 ^-4 mol per mol of silver. P using 0.5 mol / L sulfuric acid
H was adjusted to 3.8, stirring was stopped, and a settling / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.

While stirring the above silver halide dispersion, 3
Maintained at 8 ° C, 0.34% by weight of 1,2-benzoiso
5 ml of a methanol solution of thiazolin-3-one was added,
Molar ratio of spectral sensitizing dye A to spectral sensitizing dye B after 40 minutes
1: 1 methanol solution per mole of silver for spectral sensitization
1.2 × 10 as the sum of elements A and B^-3Add mole, 1 minute
Later, the temperature was raised to 47 ° C. 20 minutes after the temperature rise
Sodium sulfonate to 1 mol silver with methanol solution
7.6 × 10^-FiveMole and tellurium 5 minutes later
Sensitizer C was dissolved in a methanol solution at 2.9 × 1 per mole of silver.
0^-FourMol was added and the mixture was aged for 91 minutes. N, N'-dihydro
0.8% by weight methano of xy-N ″ -diethylmelamine
1.3 ml of ethanol solution, and 4 minutes later, 5-methyl
2-mercaptobenzimidazole in methanol
4.8 × 10 per mole of silver in liquid ^-3Mol and 1-phenyl
Ru-2-heptyl-5-mercapto-1,3,4-tri
The azole is 5.4 × with respect to 1 mol of silver in a methanol solution.
10^-3A silver halide emulsion A was prepared by molar addition.

The grains in the prepared silver halide emulsion were
Average sphere equivalent diameter 0.042 μm, coefficient of variation of sphere equivalent diameter 20
% Iodide was uniformly contained in 3.5 mol% of silver iodobromide grains. The particle size and the like were determined from the average of 1000 particles using an electron microscope. The {100} plane ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of Silver Halide Emulsions B to I >> In the preparation of silver halide emulsion A, 0.34 mass% of the divided silver halide emulsion was maintained at 38 ° C. while stirring.
5 ml of a 1,2-benzoisothiazolin-3-one methanol solution was added, and 40 minutes later, a 1: 1 methanol solution having a molar ratio of the spectral sensitizing dye A to the spectral sensitizing dye B was added to silver 1
1.2 × as the sum of the spectral sensitizing dyes A and B per mole
10 ^-3 mol was added, and the temperature was raised to 47 ° C one minute later. Heating 2
After 0 minute, 7.6 × 10 ⁻⁵ mol of sodium benzenethiosulfonate was added to 1 mol of silver with a methanol solution,
After another 5 minutes, tellurium sensitizer C was added to methanol
Five minutes after adding 2.9 × 10 ^-4 mol per mol, the noble metal sensitizer shown in Table 4 was added, and the mixture was aged for 91 minutes. N,
0.1% of N′-dihydroxy-N ″ -diethylmelamine.
1.3 ml of a 8% by weight methanol solution was added, and after a further 4 minutes, 5-methyl-2-mercaptobenzimidazole was dissolved in a methanol solution with 4.8 × 10 ⁻³ mol per mol of silver and 1-phenyl-2-heptyl. -5-mercapto-
Silver halide emulsions B to I were prepared by adding 5.4 × 10 ^-3 mol of 1,3,4-triazole to 1 mol of silver in a methanol solution.

[0257]

[Table 4]

<< Preparation of Silver Halide Emulsion 2 >> In the preparation of silver halide emulsion A, a liquid temperature of 30 ° C. during grain formation was adjusted to 4 ° C.
The temperature was changed to 7 ° C., the solution B was changed to dilute 15.9 g of potassium bromide to a volume of 97.4 ml with distilled water, and the solution D was prepared by diluting 45.8 g of potassium bromide with a volume of 400 m in distilled water.
The silver halide emulsion 2 was prepared in the same manner except that the dilution was changed to 1 and the addition time of the solution C was changed to 30 minutes to remove potassium hexacyanoferrate (II).
Precipitation / desalting / water washing / dispersion was carried out in the same manner as in silver halide emulsion A. Further, the addition amount of the methanol solution having a molar ratio of 1: 1 between the spectral sensitizing dye A and the spectral sensitizing dye B is 7.5 as the total amount of the spectral sensitizing dye A and the spectral sensitizing dye B per mole of silver.
× 10 ^-4 mol, the amount of tellurium sensitizer C added was 1.1 × 10 ^-4 mol per mol of silver, and 1-phenyl-2-heptyl-
Except that 5-mercapto-1,3,4-triazole was changed to 3.3 × 10 −3 mol per mol of silver, the same procedure as in silver halide emulsion A was carried out for spectral sensitization, chemical sensitization and Methyl-2-mercaptobenzimidazole and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole were added to obtain a silver halide emulsion 2. The silver halide emulsion 2 had an average sphere equivalent diameter of 0.08.
The particles were pure silver bromide cubic particles having a diameter of 0 μm and a coefficient of variation of the equivalent sphere diameter of 20%.

<< Preparation of Silver Halide Emulsion 3 >> In the preparation of silver halide emulsion A, a liquid temperature of 30 ° C. during grain formation was adjusted to 2 ° C.
Except that the temperature was changed to 7.degree.
Was prepared. Further, precipitation / desalting / water washing / dispersion was carried out in the same manner as in silver halide emulsion A. A 1: 1 molar ratio of the spectral sensitizing dye A to the spectral sensitizing dye B was used as a solid dispersion (aqueous gelatin solution), and the amount of the spectral sensitizing dye A was added per mole of silver.
And the spectral sensitizing dye B in the same manner as the silver halide emulsion A except that the total amount of the tellurium sensitizer C and the amount of the tellurium sensitizer C were changed to 6 × 10 ^-3 mol and 5.2 × 10 ^-4 mol per mol of silver. Thus, a silver halide emulsion 3 was obtained. The emulsion grains of the silver halide emulsion 3 were silver iodobromide grains containing 3.5 mol% of iodine having an average equivalent sphere diameter of 0.034 μm and a variation coefficient of equivalent sphere diameter of 20% uniformly.

<< Preparation of Mixed Emulsions A to I for Coating Liquid >> One of silver halide emulsions A to I is dissolved in 70% by mass, silver halide emulsion 2 is dissolved in 15% by mass, and silver halide emulsion 3 is dissolved in 15% by mass. And 1 mass% of benzothiazolium iodide
7 × 10 ⁻³ mol per mol of silver was added in an aqueous solution. Further, water was added so that the silver halide content was 38.2 g as silver per kg of the mixed emulsion for a coating solution.

<< Preparation of Dispersion of Fatty Acid Silver >> Behenic acid (product name: Edenor C22-85R, manufactured by Henkel) 8
7.6 kg, 423 L of distilled water, 5 mol / L concentration of Na
49.2 L of OH aqueous solution, 120 L of tert-butanol
Were mixed and reacted at 75 ° C. for 1 hour with stirring to obtain a sodium behenate solution. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of tert-butanol was kept at 30 ° C., and while stirring, the whole amount of the sodium behenate solution and the whole amount of the silver nitrate aqueous solution were supplied at constant flow rates of 93 minutes, 15 seconds and 90 minutes, respectively. And added. At this time, only the aqueous silver nitrate solution was added for 11 minutes after the addition of the aqueous silver nitrate solution was started, and then the addition of the sodium behenate solution was started. After the addition of the aqueous silver nitrate solution was completed, only the sodium behenate solution was added for 14 minutes and 15 seconds. I was doing it. At this time, the temperature inside the reaction vessel was set at 30 ° C., and the external temperature was controlled so that the liquid temperature became constant. The piping of the addition system of the sodium behenate solution was kept warm by steam tracing, and the steam opening was adjusted so that the liquid temperature at the outlet at the tip of the addition nozzle became 75 ° C. The piping of the silver nitrate aqueous solution addition system was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically with respect to the stirring axis, and were adjusted to a height such that they did not come into contact with the reaction solution.

After the addition of the sodium behenate solution was completed, the mixture was left to stir at the same temperature for 20 minutes, and the temperature was lowered to 25 ° C. Thereafter, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of the filtered water became 45 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying. When the morphology of the obtained silver behenate particles was evaluated by electron micrographing,
A = 0.14 μm, b = 0.4 μm, c = 0.
6 μm, average aspect ratio 5.2, average sphere equivalent diameter 0.5
It was a scaly crystal having a diameter of 2 μm and a coefficient of variation of the equivalent spherical diameter of 15%. (A, b, c are prescribed in the text) 100% dry solids
7.4 g of polyvinyl alcohol (trade name: PVA-217) and water were added to a wet cake equivalent to 1 g, and the total amount was reduced to 385 g, followed by preliminary dispersion with a homomixer. Next, the predispersed undiluted solution is dispersed in a dispersing machine (Microfluidizer M-110S-, manufactured by Microfluidics International Corporation).
The pressure of EH and G10Z interaction chamber was adjusted to 1750 kg / cm ² , and the mixture was treated three times to obtain a silver behenate dispersion. In the cooling operation, a coiled heat exchanger was mounted before and after the interaction chamber, and the dispersion temperature was set at 18 ° C. by adjusting the temperature of the refrigerant.

<< Preparation of 25% by Mass Dispersion of Reducing Agent >> 10 kg of the exemplified compound (I-14) of the above general formula (I) and modified polyvinyl alcohol (Poval MP, manufactured by Kuraray Co., Ltd.)
16 kg of water was added to 10 kg of the 20% by mass aqueous solution of 203) and mixed well to form a slurry. The slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2, manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 3 hours and 30 minutes, and then benzoisothiazolinone sodium salt was added. 0.2 g and water were added to adjust the concentration of the reducing agent to 25% by mass to obtain a reducing agent dispersion. The reducing agent particles contained in the thus obtained reducing agent dispersion had a median diameter of 0.42 μm and a maximum particle diameter of 2.0 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 20% Dispersion of Hydrogen Bonding Compound >> Exemplified Compound (II-1) 1 of the above hydrogen bonding compound
0 kg and denatured polyvinyl alcohol (Kuraray Co., Ltd.
Poval MP203) to 10 kg of a 20% by mass aqueous solution,
16 kg of water was added and mixed well to form a slurry.
This slurry was sent by a diaphragm pump, and was fed for 3 hours with a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm.
After dispersing for 0 minute, 0.2 g of benzoisothiazolinone sodium salt and water are added to the mixture to reduce the concentration of the hydrogen bonding compound to 20.
It was prepared so as to be in a mass% to obtain a dispersion. The additive particles contained in the dispersion thus obtained have a median diameter of 0.42 μm.
m, and the maximum particle diameter was 1.6 μm or less. The obtained dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 10% by Mass Dispersion of Mercapto Compound >> 1-phenyl-2-heptyl-5-mercapto-
5 kg of 1,3,4-triazole and 20 of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.)
8.3 kg of water was added to 5 kg of a mass% aqueous solution and mixed well to form a slurry. This slurry was sent by a diaphragm pump and filled with zirconia beads having an average diameter of 0.5 mm in a horizontal sand mill (manufactured by Imex Co., Ltd.).
After dispersion for 6 hours in UVM-2), water was added to adjust the concentration of the mercapto compound to 10% by mass,
A mercapto dispersion was obtained. The mercapto compound particles contained in the thus obtained dispersion of the mercapto compound had a median diameter of 0.40 μm and a maximum particle diameter of 2.0 μm or less. The resulting mercapto compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored. Immediately before use, the hole diameter is 10
The mixture was filtered through a μm polypropylene filter.

<< Preparation of 20% by Mass Dispersion of Organic Polyhalogen Compound-1 >> Tribromomethylnaphthyl sulfone 5
and 2.5 kg of a 20% by mass aqueous solution of modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval MP203),
Sodium triisopropylnaphthalenesulfonate 2
213 g of a 0% by mass aqueous solution and 10 kg of water were added and mixed well to form a slurry. This slurry was fed by a diaphragm pump and filled with zirconia beads having an average diameter of 0.5 mm in a horizontal sand mill (IMEX Co., Ltd.).
After dispersing for 5 hours by UVM-2), 0.2 g of benzoisothiazolinone sodium salt and water are added to adjust the concentration of the organic polyhalogen compound to 20% by mass. I got something. Organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.36 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 25% by mass dispersion of organic polyhalogen compound-2 >> 20% by mass of organic polyhalogen compound
Same as Dispersion-1, except that 5 kg of tribromomethylnaphthyl sulfone was used instead of tribromomethyl (4-
5 kg of (2,4,6-trimethylphenylsulfonyl) phenyl) sulfone was dispersed, diluted so that the organic polyhalogen compound became 25% by mass, and filtered. The organic polyhalogen compound particles contained in the organic polyhalogen compound dispersion thus obtained had a median diameter of 0.3.
8 μm, and the maximum particle size was 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 26% by mass of organic polyhalogen compound dispersion-3 >> 20% by mass of organic polyhalogen compound
Similar to Dispersion-1, except that 5 kg of tribromomethylphenylsulfone was used instead of 5 kg of tribromomethylnaphthylsulfone,
kg and dispersed.
It diluted so that it might be set to mass%, and filtered. The organic polyhalogen compound particles contained in the organic polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored. After storage, it was stored at 10 ° C. or lower until use.

<< Preparation of 5% by mass solution of phthalazine compound >> 8 kg of modified polyvinyl alcohol MP203 manufactured by Kuraray Co., Ltd. was dissolved in 174.57 kg of water, and then 3.15 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate was added. 14.28 kg of a 70% by mass aqueous solution of 6-isopropylphthalazine was added to prepare a 5% by mass solution of 6-isopropylphthalazine.

<< Preparation of 20% by Mass Dispersion of Pigment >>
I. Pigment Blue 60 and 64 g of Demol N manufactured by Kao Corporation were added to 250 g of water and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm is prepared and put in a vessel together with the slurry, and then a dispersing machine (manufactured by Imex Co., Ltd., 1 / 4G
(Sand grinder mill) for 25 hours to obtain a pigment dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<< Preparation of SBR Latex 40% by Mass >> The following SBR latex diluted 10 times with distilled water was subjected to ultrafiltration (UF) purification module (manufactured by Daisen Membrane System Co., Ltd., FS03-FC). -FUY0
Using 3A1), dilute and purify until the ionic conductivity becomes 1.5 mS / cm, and Sandet-BL manufactured by Sanyo Chemical Industries, Ltd.
Was added to be 0.22% by mass. Further, Na ⁺ ion: NH ₄ ⁺ ion = 1: using NaOH and NH ₄ OH.
The mixture was added to 2.3 (molar ratio) and adjusted to pH 8.4. The latex concentration at this time was 40% by mass. (SBR latex: -St (71) -Bu (2
6) Latex of -AA (3)-) Average particle size 0.1 μm, concentration 45 mass%, equilibrium water content at 25 ° C, relative humidity 60% 0.6 mass%, ion conductivity 4.2 mS / cm (ion The conductivity was measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd., and the latex stock solution (40% by mass) was measured at 25 ° C.), pH 8.2.

<< Preparation of Image Forming Layer Coating Solutions A to I >> 1.1 g of a 20% by mass dispersion of the pigment obtained above, 103 g of a fatty acid silver dispersion, and polyvinyl alcohol (manufactured by Kuraray Co., Ltd.)
5 g of a 20% by mass aqueous solution of PVA-205) and 2 g of a reducing agent
25.0 g of 5 mass% dispersion, 20% of hydrogen bonding compound
The dispersion was used in an amount of 100 mol% based on the amount of the reducing agent, and organic polyhalogen compound dispersions-1, -2, and -3 were mixed in a ratio of 5: 1: 3.
(Mass ratio) 14.0 g in total, 10 of mercapto compound
5.8 g of mass% dispersion, purified by ultrafiltration (UF)
Adjusted SBR latex (Tg: 24 ° C.) 40% by mass
106 g of a 5% by mass solution of a phthalazine compound 18 m
1, 5% methanol / water (1%)
/ 1) was added successively at 3 mol% based on the amount of reducing agent used, and immediately before coating, 10 g of each of the mixed emulsions A to I for a coating solution was mixed well (image forming layer (emulsion layer, photosensitive layer)). Layer) 70ml of coating solution as it is to coating die
/ M ² and applied. The viscosity of the image forming layer coating solution was measured with a B-type viscometer of Tokyo Keiki Co., Ltd.
85 [mPa ·] at ℃ (No. 1 rotor, 60 rpm)
s]. 25 using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd.
The viscosity of the coating solution at 0 ° C. is such that the shear rate is 0.1, 1, 10, 1
1500 at 00 and 1000 [1 / sec], respectively.
220, 70, 40, and 20 [mPa · s].

<< Preparation of Coating Solution for Intermediate Layer on Image Forming Surface >> 772 g of a 10% by mass aqueous solution of polyvinyl alcohol (PVA-205, manufactured by Kuraray Co., Ltd.), 5.3 g of a 20% by mass dispersion of pigment, methyl methacrylate / styrene / Butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 64/9/20/5/2)
Aerosol O is added to 226 g of latex 27.5 mass% liquid.
2 ml of a 5 mass% aqueous solution of T (manufactured by American Cyanamid Co.), 10.5 ml of a 20 mass% aqueous solution of diammonium phthalate, and water were added so that the total amount becomes 880 g.
The solution was adjusted with NaOH so that the pH became 7.5, and the solution was applied to the coating die so as to be 10 ml / m ² , as an intermediate layer coating solution. The viscosity of the coating solution is 40 ° C (N
o. It was 21 [mPa · s] with one rotor at 60 rpm.

<< Preparation of Coating Solution for First Layer of Image Forming Surface Protective Layer >>
64 g of inert gelatin was dissolved in water, and 27.5% by mass of methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 64/9/20/5/2) latex was used.
80 g of a liquid, a 10% by mass methanol solution of phthalic acid
ml, 10% by weight aqueous solution of 4-methylphthalic acid 23m
1, 28 ml of sulfuric acid having a concentration of 0.5 mol / L, 5 ml of a 5% by mass aqueous solution of aerosol OT (manufactured by American Cyanamid), 0.5 g of phenoxyethanol, and 0.1 g of benzoisothiazolinone were added to a total amount of 750 g. Water was added to make a coating solution, and a mixture prepared by mixing 26 ml of 4% by mass chromium alum with a static mixer immediately before coating was sent to a coating die at 18.6 ml / m ² . The viscosity of the coating solution is 40 ° C (N
o. It was 17 [mPa · s] with one rotor at 60 rpm.

<< Preparation of Coating Solution for Second Layer of Image Forming Surface Protective Layer >>
80 g of inert gelatin is dissolved in water, and 27.5% by mass of methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 64/9/20/5/2) latex
Liquid 102 g, N-perfluorooctylsulfonyl-N
3.2% by weight of a 5% by weight solution of potassium propylalanine salt.
32 ml of a 2% by weight aqueous solution of polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [average degree of polymerization of ethylene oxide = 15], Aerosol OT (manufactured by American Cyanamid Co.) 23% of a 5% by mass solution of polymethyl methacrylate (average particle diameter 0.7 μm)
4 g, polymethyl methacrylate fine particles (average particle size of 4.
5 μm) 21 g of 4-methylphthalic acid, 1.6 g of phthalic acid, 4.8 g of phthalic acid, 44 ml of sulfuric acid having a concentration of 0.5 mol / L, and 10 mg of benzoisothiazolinone were added with water so that the total amount became 650 g, and 4% by mass of chromium was added. Alum and 0.6
Immediately before coating, 445 ml of an aqueous solution containing 7% by mass of phthalic acid was mixed with a static mixer to obtain a surface protective layer coating solution, which was then sent to a coating die at 8.3 ml / m ² . The viscosity of the coating solution is 40 ° C with a B-type viscometer.
9 [mPa · s] at (No. 1 rotor, 60 rpm)
Met.

<< Preparation of Photothermographic Materials 1 to 21 >> The anti-halation layer coating solution was applied on the back surface side of the undercoating support so that the coating amount of the solid fine particle dye was 0.04 g / m ² . Further, the coating solution for the back surface protective layer was simultaneously coated in a multilayer so that the coating amount of gelatin was 1.7 g / m ^2, and dried to prepare a back layer. The image forming layer (a silver halide coating amount of 0.14 g)
/ M ² ), an intermediate layer, a protective layer first layer, and a protective layer second layer were simultaneously coated in order by a slide bead coating method to produce a photothermographic material sample. The coating and drying conditions are as follows. The coating is performed at a speed of 160 m / min, and the gap between the tip of the coating die and the support is set to 0.10 to 0.1.
30 mm, and the pressure in the decompression chamber is 196 to
882 Pa was set lower. The support was neutralized with ion wind before coating. Dry-bulb temperature 1 in subsequent chilling zone
After the coating solution is cooled by a wind of 0 to 20 ° C., the coating solution is conveyed in a non-contact type, and dried at a dry bulb temperature of 23 with a helix type non-contact drying device.
It dried with the dry air of -45 degreeC, and the wet bulb temperature of 15-21 degreeC. After drying, the humidity was controlled at 25 ° C at a relative humidity of 40 to 60%, and the film surface was heated to 70 to 90 ° C. After heating, the film surface was cooled to 25 ° C. The matte degree of the produced photothermographic material was Beck's smoothness, and was 55% on the image forming layer side.
0 seconds and the back surface was 130 seconds. Further, the pH of the film surface on the image forming surface side was measured and found to be 6.0.

[0277]

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[0278]

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[0279]

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<< Evaluation >> (Evaluation of photographic performance) The obtained sample was cut into half cut pieces, packaged in the following packaging material in an environment of 25 ° C. and a relative humidity of 50%, and stored at room temperature for 2 weeks. The following evaluation was performed. (Packaging material) PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene containing 3% carbon 50 μm Oxygen permeability: 0 ml / Pa · m ² · 25 ° C. · day, moisture permeability: 0 g / Pa · m ²・ 25 ℃ ・ day

A sample of the prepared photothermographic material was used on a Fuji Medical Dry Laser Imager FM-DP L.
(With a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)) and heat exposure (about 11
After performing 24 seconds with four panel heaters set at 2 ° C. to 119 ° C. to 121 ° C. to 121 ° C., the relative sensitivity (ΔS) and fog density of each sample were measured. These values are also shown in Table 5.
It was described in.

(Evaluation of Silver Tone Difference of Image) A sample of each prepared photothermographic material was subjected to a Fuji Medical Dry Laser Imager FM-DPL (maximum 60 mW (IIIB)).
(A 660 nm semiconductor laser with an output). Then, the standard thermal development temperature (about 112
4 ° C.-119 ° C.-121 ° C.-121 ° C. for 24 seconds), and heat development was performed at + 3 ° C. and −3 ° C., respectively. The difference in silver tone under each temperature condition was visually evaluated according to the following criteria. Table 5 shows the results.

<Evaluation> ：: Good with almost no silver tone difference due to temperature conditions. ：: The silver tone difference due to the temperature condition is small but can be identified. Δ: Large difference in silver tone due to temperature conditions, but acceptable. X: The silver tone difference due to the temperature condition is a significant problem.

(Evaluation of Dependence on System Environment) A Fuji Medical Dry Laser Imager FM-DPL (with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)) was installed in a thermo-hygrostat at 32 ° C. and a relative humidity of 70.
%, 32 ° C, relative humidity 10%, 13 ° C, relative humidity 70%
The photothermographic material was exposed and thermally developed under four conditions of 13 ° C. and 25% relative humidity, and the obtained image was evaluated with a densitometer. For the exposure amount giving a density of 1.2 under the conditions of 25 ° C. and a relative humidity of 60%, the actually obtained density was measured, and the maximum value and the minimum value of the output density under the above four conditions were measured. The differences were compared. Table 5 shows the results.

[0285]

[Table 5]

Table 5 shows that the photothermographic material of the present invention chemically sensitized with a metal sensitizer is excellent in sensitivity, fog, image color tone and environment dependency. Also,
It can be seen that when the compound of the general formula (D) is contained, the sensitivity, the color tone of the image and the environment dependency are further improved.

[0287]

The photothermographic material of the present invention has low fog, good storability, high sensitivity and high Dmax (maximum density).
In addition, it has the characteristics of satisfying a high color tone and having a small temperature dependence and temperature during development.

Claims (5)

[Claims] 1. A photothermographic material comprising an image forming layer containing a non-photosensitive organic silver salt, a photosensitive silver halide, a reducing agent for silver ions, and a binder on one surface of a support. 90% or more of the developed silver when exposed to heat at 121 ° C. for 24 seconds after exposure is in contact with the photosensitive silver halide grains after development, and the photosensitive silver halide is a noble metal. A photothermographic material characterized by being chemically sensitized with a sensitizer. 2. The noble metal sensitizer is represented by the following general formula (a):
The photothermographic material according to claim 1, which is a compound represented by the formula: General formula (a) [L-Au-L] M (wherein L represents an organic mercapto ligand and M represents a cationic counter ion, provided that the complex is symmetric.) 3. The noble metal sensitizer according to the following general formula (b):
The photothermographic material according to claim 1, which is a compound represented by the formula: General formula (b) [Au (R) ₂ ] ⁺ X ⁻ (wherein, R represents a ligand, and two Rs may be the same or different from each other, and at least one is a mesoionic coordination. .X representing the child ^- represents an anion). 4. The image forming layer according to claim 1, wherein the image forming layer contains a compound represented by the following general formula (D).
4. The photothermographic material according to any one of the above items 3. General formula (D) Q ¹ -NHNH-Q ² [In general formula (D), Q ¹ is a carbon atom and represents -NHNH
An aromatic group or a heterocyclic group bonded to -Q ^2, Q ²
Represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group. ] 5. The photothermographic material according to claim 1, wherein in the compound represented by the formula (D), Q ² is a carbamoyl group.