JP2006078901A - Heat developable photosensitive material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high sensitivity and excellent storage stability, and an image forming method. <P>SOLUTION: The heat developable photosensitive material contains, on one surface of a support, at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder. The image forming method is also provided. The heat developable photosensitive material is characterized by containing a compound represented by formula (AR) wherein A represents a quaternary salt structure of nitrogen or phosphorus as a group that is adsorptive to a silver halide; l represents an integer of 1-5; W represents a linking group; m represents 0 or 1; n represents an integer of 1-5; and B represents a reducing group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photothermographic material and an image forming method, and more particularly to a photothermographic material and an image forming method using a silver halide emulsion having a high silver iodide content.

  In recent years, in the medical field and the printing plate making field, dry development of photographic development processing is strongly desired from the viewpoint of environmental protection and space saving. In these areas, digitization has progressed, and image information is captured and stored on a computer, stored, and processed if necessary, and output to photosensitive materials by laser image setter or laser imager where necessary by communication. However, systems that develop and produce images on the spot are rapidly spreading. As a photosensitive material, it is necessary to form a clear black image that can be recorded by laser exposure with high illuminance and has high resolution and sharpness. As such digital imaging recording materials, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems, but the diagnostic ability is determined like medical images. It is unsatisfactory in terms of image quality (sharpness, graininess, gradation, color tone) and recording speed (sensitivity), and has not yet reached a level that can replace the conventional silver salt film for wet development.

  On the other hand, a thermal image forming system using an organic silver salt is known. In particular, a photothermographic material generally contains a photosensitive silver halide, a reducing agent, a reducible silver salt (eg, an organic silver salt), and, if necessary, a toning agent for controlling the color tone of silver dispersed in a binder matrix. A photosensitive layer.

  The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and is blackened by an oxidation-reduction reaction between silver halide or a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. Form a silver image. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. As a result, a black silver image is formed in the exposed area. The photothermographic material is disclosed in many documents such as US Pat. No. 2,910,377 and Japanese Patent Publication No. 43-4924, and Fuji Medical Dry Imager FM-DP L is practically used as a medical image forming system. Released.

  In such an image forming system using an organic silver salt, since there is no fixing step, image storage stability after development processing, in particular, deterioration of printout when exposed to light has been a serious problem. Methods for utilizing silver iodide formed by converting an organic silver salt as means for improving this printout are disclosed in US Pat. No. 6,143,488 and EP0922995. However, the method of converting an organic silver salt as disclosed herein with iodine cannot obtain sufficient sensitivity, and it is difficult to construct an actual system. Other photosensitive materials using silver iodide are described in WO97-48014, WO48015, US-6165705, JP-A-8-297345, Japanese Patent No. 2785129, etc., all of which have sufficient sensitivity and fogging level. Has not been achieved.

  As a means of increasing the sensitivity of silver iodide photographic emulsions, sensitization by immersion in halogen acceptors such as sodium nitrite, pyrogallol, hydroquinone, etc. or silver nitrate aqueous solution, or sulfur sensitization with pAg7.5 Was known). However, the sensitizing effect of these halogen acceptors was very small and extremely insufficient in the photothermographic material targeted by the present invention.

It is known to use a compound having an adsorbing group and a reducing group as means for increasing the sensitivity of photosensitive silver iodide used in a photothermographic material (see, for example, Patent Document 1).
However, the performance required for the photothermographic material has many items in addition to the sensitivity, and it is not practical until the comprehensive performance satisfying all of these is realized. From this point, there is nothing that is still satisfactory, and an even better sensitizing technique has been required.
JP 2004-184430 A

  An object of the present invention is to provide a photothermographic material and an image forming method having high sensitivity and excellent storage stability. In particular, it is to provide a photothermographic material and an image forming method having high sensitivity and excellent storage stability by using silver halide having a high silver iodide content.

The above object of the present invention has been achieved by the following means.
<1> A photothermographic material containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder on one surface of a support, the following general formula A photothermographic material comprising a compound represented by (AR).

In general formula (AR), A represents a quaternary salt structure of nitrogen or phosphorus as an adsorptive group to silver halide, and l represents an integer of 1 to 5. W represents a linking group, m represents 0 or 1, and n represents an integer of 1 to 5. B represents a reducing group.
<2> The photothermographic material according to <1>, wherein in the general formula (AR), the adsorptive group of A to silver halide has a quaternary salt structure of nitrogen.
<3> In the above general formula (AR), the adsorptive group to silver halide of A is a 5-membered or 6-membered nitrogen-containing aromatic heterocycle containing a quaternized nitrogen atom. The photothermographic material according to <2>.
<4> The photothermographic material according to any one of <1> to <3>, wherein n is 2 to 5 in the general formula (AR).
<5> The reducing group of the general formula (AR) is a formyl group, an amino group, a triple bond group such as an acetylene group or a propargyl group, an alkyl mercapto group, or an aryl mercapto group of <1> to <4> The photothermographic material according to claim 1.
<6> Any one of <1> to <4>, wherein the reducing group of the general formula (AR) is any group selected from the groups represented by the following (B ₁ ) to (B ₃ ): The photothermographic material according to item:
(In the formula, in the groups represented by the following (B ₁ ) to (B ₃ ), R _b1 and R _b2 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Represents.)

<7> Any one of <1> to <4>, wherein the reducing group of the general formula (AR) is a group derived from any of reductones, phenols, naphthols, and phenylenediamines. The photothermographic material described in 1.
<8> The photothermographic material according to any one of <1> to <7>, wherein the silver halide photographic emulsion has a silver iodide content of 40 mol% to 100 mol%. .
<9> The photothermographic material according to any one of <1> to <8>, wherein the silver halide photographic emulsion has a silver iodide content of 80 mol% to 100 mol%. .
<10> The photothermographic material according to any one of <1> to <9>, wherein the silver halide photographic emulsion contains tabular grains having an average aspect ratio of 2 or more.
<11> The photothermographic material according to <10>, wherein the tabular grains have an average aspect ratio of 5 or more and 50 or less.
<12> The photothermographic material according to <10> or <11>, wherein the tabular grains have an average equivalent sphere diameter of 0.1 μm to 10 μm.
<13> The photothermographic material according to any one of <1> to <12>, wherein the silver halide photographic emulsion is spectrally sensitized.
<14> The photothermographic material according to any one of <1> to <13>, wherein the image forming layer is provided on both sides of a support.
<15> The photothermographic material according to any one of <1> to <14> is in close contact with a fluorescent intensifying screen containing a phosphor having an emission wavelength of 350 nm or more and 420 nm or less and exposed to X-rays. An image forming method.
<16> The image forming method according to <15>, wherein the phosphor is a divalent Eu-activated phosphor.
<17> The image forming method according to <15> or <16>, wherein the phosphor is a divalent Eu-activated barium halide phosphor.

  A photothermographic material and an image forming method having high sensitivity and excellent storage stability are provided. In particular, using a silver halide having a high silver iodide content, a photothermographic material and an image forming method having high sensitivity and excellent storage stability are provided.

  The present invention relates to a photothermographic material and an image forming method, and more particularly to a photothermographic material and an image forming method using a silver halide emulsion having a high silver iodide content. The present invention relates to a photothermographic material and an image forming method in which the stability of the photosensitive material before development processing is excellent and the image storage stability after development processing is excellent.

The present invention is described in detail below.
1. Photothermographic material The photothermographic material of the present invention has an image forming layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support. . Preferably, an intermediate layer and a surface protective layer may be provided on the image forming layer, or a back layer and a back protective layer may be provided on the opposite surface. A “double-sided photothermographic material” having image forming layers on both sides of the support is also preferred in the present application.
The configuration of each layer and preferred components thereof will be described in detail.

  More specifically, examples of the compound having an adsorbing group and a reducing group for silver halide used in the present invention include compounds represented by the following general formula (I).

General formula (I) [(A) _1- (W) m] n-B

In general formula (I), A represents a group that can be adsorbed to silver halide (hereinafter referred to as an adsorptive group), and l represents an integer of 1 to 5. W represents a linking group, m represents 0 or 1, n represents an integer of 1 to 5, and when n is 2 or more, the effect of the present invention appears more remarkably. B represents a reducing group.
Next, the general formula (I) will be described in detail.
In general formula (I), it represents a quaternary salt structure of nitrogen or phosphorus as an adsorptive group to silver halide represented by A. Specifically, the quaternary salt structure of nitrogen is an ammonio group or a group containing a nitrogen-containing heterocyclic group containing a quaternized nitrogen atom. Here, the ammonio group is a trialkylammonio group, a dialkylaryl (or heteroaryl) ammonio group, an alkyldiaryl (or heteroaryl) ammonio group, and the aryl group here is an aromatic hydrocarbon group such as a phenyl group. And a heteroaryl group refers to an aromatic heterocyclic group such as a furyl group or a thienyl group. Specific examples of the ammonio group include benzyldimethylammonio group, trihexylammonio group, and phenyldiethylammonio group.
As the nitrogen-containing heterocyclic group containing a quaternized nitrogen atom, a 4-membered to 8-membered nitrogen-containing heterocyclic ring is used, which may be a monocyclic structure or a condensed ring structure. Examples thereof include a pyridinio group, an imidazolio group, a quinolinio group, an isoquinolinio group, a benzoxazolio group, a benzothiazolio group, a benzoimidazoliopyridinio group, and an imidazolio group.
Further, a mercapto group substituted with a nitrogen-containing heterocyclic group substituted with a mercapto group may be dissociated to form a meso ion. Examples of such a heterocyclic group include an imidazolium ring group, a pyrazolium ring group, a thiazolium ring group. , Triazolium ring group, tetrazolium ring group, thiadiazolium ring group, pyridinium ring group, pyrimidinium ring group, triazinium ring group and the like.

  The nitrogen quaternary salt structure is preferably a 5- or 6-membered nitrogen-containing heterocyclic group containing a quaternized nitrogen atom, more preferably a 5- or 6-membered nitrogen-containing aromatic heterocyclic group. Is used. More preferred are a pyridinio group, a quinolinio group, an isoquinolinio group, a benzoxazolio group, a benzothiazolio group, a benzoimidazoliopyridinio group and an imidazolio group, and particularly preferred are a pyridinio group, a quinolinio group and an isoquinolinio group. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent, but the substituent is preferably an alkyl group, an aryl group, an acylamino group, a chloro atom, an alkoxycarbonyl group, A carbamoyl group etc. are mentioned, Especially preferably, it is an aryl group.

  The quaternary salt structure of phosphorus represents a trialkylphosphonio group, a dialkylaryl (or heteroaryl) phosphonio group, an alkyldiaryl (or heteroaryl) phosphonio group, or a triaryl (or heteroaryl) phosphonio group. The aryl group here represents an aromatic hydrocarbon group such as a phenyl group, and the heteroaryl group refers to an aromatic heterocyclic group such as a furyl group or a thienyl group. An alkyldiarylphosphonio group and a triarylphosphonio group are preferably used, and a triarylphosphonio group is particularly preferably used.

  As the quaternary salt structure, a quaternary salt structure of nitrogen is preferably used, and a pyridinio group is more preferably used. In the compound of the general formula (I), one or more such quaternary salt structures may be present in the molecule, but two or more are preferable. Furthermore, it is particularly preferable that two or three are present. When a plurality of quaternary salt structures are present in one molecule, they may be the same group or different.

Examples of quaternary salt counter anions include halogen ions such as chlorine ion, bromine ion and iodine ion, carboxylate ions such as acetate ion, oxalate ion, fumarate ion and benzoate ion, p-toluenesulfonate, methanesulfonate Sulfonate ions such as butane sulfonate and benzene sulfonate, sulfate ions, perchlorate ions, carbonate ions, nitrate ions, BF ₄ −, PF ₆ —, Ph ₄ B— and the like. When a group having a negative charge in the carboxylate group or the like is present in the molecule, an inner salt may be formed together with the group. As the counter anion not present in the molecule, halogen ion, carboxylate ion, methanesulfonate ion, sulfate ion, BF ₄ ⁻ , and PF ₆ ⁻ are preferable, and chloro ion, bromo ion, and methanesulfonate ion are particularly preferable.

In addition to quaternary salts, other silver halide adsorptive groups such as mercapto groups (or salts thereof), benzotriazolyl groups and the like may be present simultaneously.
Specific examples of other adsorptive groups further include those described in pages 4 to 7 of JP-A No. 11-95355.

In general formula (I), the linking group represented by W represents a linking group composed of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom, specifically an alkylene group having 1 to 20 carbon atoms. (Methylene group, ethylene group, trimethylene group, tetramethylene group, hexamethylene group, etc.), arylene group having 6 to 20 carbon atoms (phenylene group, naphthylene group, etc.), -CONR _1- , -SO ₂ NR ₂ -,- 〇 -, - S -, - NR 3 -, - NR 4 CO -, - NR 5 SO 2 -, - NR 6 CONR 7 -, - COO -, - OCO- , and the like. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ represents a hydrogen atom, an aliphatic group or an aromatic group.

In the general formula (I), the aliphatic group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ is preferably one having 1 to 30 carbon atoms, particularly carbon. A linear, branched or cyclic alkyl group, alkenyl group, alkynyl group, or aralkyl group having 1 to 20 formulas. Examples of the alkyl group, alkenyl group, alkynyl group, and aralkyl group include, for example, methyl group, ethyl group, isopropyl group, t-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, and cyclopentyl. Group, cyclohexyl group, allyl group, 2-butenyl group, 3-pentenyl group, propargyl group, 3-pentynyl group, benzyl group and the like.

In the general formula (I), the aromatic group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ is preferably one having 6 to 30 carbon atoms, A monocyclic or condensed ring aryl group having 6 to 20 carbon atoms, such as a phenyl group and a naphthyl group.

Each of the above groups may be combined to form a divalent linking group. Preferably, a methylene group, an ethylene group, a trimethylene group, a phenylene group, —CONR ₁ —, —SO ₂ NR ₂ —, —NR ₄ CO—, —NR ₅ SO ₂ —, —NR ₆ CONR ₇ —, —COO—, -OCO- and the like. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ represents a hydrogen atom, an aliphatic group or an aromatic group.

In the general formula (I), the aliphatic group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ is preferably one having 1 to 30 carbon atoms, particularly carbon. A linear, branched or cyclic alkyl group, alkenyl group, alkynyl group, or aralkyl group having 1 to 20 formulas. Examples of the alkyl group, alkenyl group, alkynyl group, and aralkyl group include, for example, methyl group, ethyl group, isopropyl group, t-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, and cyclopentyl. Group, cyclohexyl group, allyl group, 2-butenyl group, 3-pentenyl group, propargyl group, 3-pentynyl group, benzyl group and the like.

In the general formula (I), the aromatic group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ or R ₇ is preferably one having 6 to 30 carbon atoms, A monocyclic or condensed ring aryl group having 6 to 20 carbon atoms, such as a phenyl group and a naphthyl group.

In the general formula (I), the reducing group represented by B may be any functional group capable of reducing silver halide, specifically, a triple bond group such as a formyl group, amino group, acetylene group or propargyl group, an alkyl group. Mercapto group, aryl mercapto group, groups represented by general formulas (B ₁ ) to (B ₃ ) described later, and groups derived from any of reductones, phenols, naphthols, and phenylenediamines described below Etc. Among them, formyl group, amino group, triple bond group, groups represented by (B ₁ ) to (B ₃ ), and reductones, phenols, naphthols, phenylenediamines, 1-phenyl-3-pyrazolidones Groups derived from either are preferred.
Specific examples of the compound of the present invention in which the reducing group is a formyl group, amino group, triple bond group or the like are shown below, but the compound of the present invention is not limited thereto.

In another preferred compound having an adsorbing group and a reducing group for the silver halide of the present invention, the reducing group of the general formula (I) is represented by the following (B ₁ ) to (B ₃ ). A compound which is any group selected from Here, in the groups represented by the following (B ₁ ) to (B ₃ ), R _b1 and R _b2 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. To express.

The alkyl group represented by R _b1 and R _b2 in ((B ₁ ) to (B ₃ )) is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, n-propyl, i -Propyl, cyclopropyl, i-butyl, cyclohexyl, t-octyl, decyl, dodecyl, hexadecyl, benzyl), more preferably an unsubstituted linear alkyl group, most preferably a methyl group.

The alkenyl group represented by R _b1 and R _b2 is preferably a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms (for example, vinyl, allyl, 2-butenyl, oleyl, i-propenyl), more preferably unsubstituted. A straight-chain alkenyl group, and most preferably allyl.
The alkynyl group represented by R _b1 and R _b2 is preferably a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms (for example, ethynyl, propargyl, trimethylsilylethynyl group), more preferably an unsubstituted linear alkynyl group. It is.
The aryl group represented by R _b1 and R _b2 is preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms (for example, phenyl or naphthyl), more preferably a substituted or unsubstituted phenyl.

The heterocyclic group represented by R _b1 and R _b2 is one obtained by removing one hydrogen atom from a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound having 3 to 20 carbon atoms. A valent group (for example, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl) is preferable, and an aromatic heterocyclic group is more preferable. These groups may have a substituent.
R _b1 is preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a methyl group. R _b2 is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

Still another preferred compound of the present invention having an adsorbing group and a reducing group on silver halide is that the reducing group of the general formula (I) is a reductone, phenol, naphthol, and phenylenediamine. A compound that is a group derived from any of the classes. Examples of phenols include hydroxybenzenes, dihydroxybenzenes, polyhydroxybenzenes (such as pyrogallol), aminophenols, and sulfonamidophenols. Examples of naphthols include 1,4-naphthols and 1,5-naphthols. A group in which one of the hydrogen atoms on the benzene ring of these compounds is removed and becomes a substitution position can be the reducing group of the present invention.
Of these, a group derived from either phenols or naphthols is preferably a reducing group.

  More specifically, examples of the group derived from phenols include compounds represented by the following.

In the formula, as R _{a1 to} R _a5 , for example, a hydrogen atom, a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), Alkynyl group, aryl group, heterocyclic group (may be referred to as heterocyclic group), cyano group, hydroxyl group, nitro group, carboxyl group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, Carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino Groups, alkyl and Reelsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl Group, aryl and heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (-B (OH ₂ ), phosphato group (—OPO (OH) ₂ ), sulfato group (—OSO ₃ H) and other known substituents. However, at least one of R _{a1 to} R _a5 is a hydrogen atom, and at least one of R _{a1 to} R _a5 is a linking group of the general formula (I).

The alkyl group is preferably a linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and examples thereof include butyl, hexyl, and benzyl.
The aryl group is preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The heterocyclic group represents a 5-membered to 7-membered, monocyclic or condensed, aromatic or non-aromatic heterocyclic group, such as a pyridine ring group, a pyrimidine ring group, a triazine ring group, a thiazole ring group, Benzothiazole ring group, oxazole ring group, benzoxazole ring group, imidazole ring group, benzimidazole ring group, pyrazole ring group, indazole ring group, indole ring group, purine ring group, quinoline ring group, isoquinoline ring group, quinazoline ring group Etc.

Other examples of the acyl group include an acetyl group, a chloroacetyl group, and a trifluoroacetyl group. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group. Examples of the arylsulfonyl group include a benzenesulfonyl group and p-toluenesulfonyl. Examples of the carbamoyl group such as a group and p-chlorophenylsulfonyl group include an N-phenylcarbamoyl group and an N-methylcarbamoyl group, and examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
More specifically, examples of the group derived from naphthols include compounds represented by the following.

In the formula, either X or Y is a hydroxyl group and the other is a hydrogen atom. R _{c1 to} R _c5 include a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (also referred to as a heterocyclic group), a cyano group, a hydroxyl group, a nitro group, and a carboxyl group. , Alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, amino Carbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl group And arylsulfinyl groups, alkyl and arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, carbamoyl groups, aryl and heterocyclic azo groups, imide groups, phosphino groups, phosphinyl groups, phosphinyloxy groups, phosphini Ruamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (—B (OH) ₂ ), phosphato group (—OPO (OH) ₂ ), sulfato group (—OSO ₃ H), other Known substituents are listed as examples. However, at least one of X, Y and R _{c1 to} R _c5 is a hydrogen atom, and at least one is a linking group of the general formula (I).

The alkyl group is preferably a linear, branched, or cyclic alkyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and examples thereof include butyl, hexyl, and benzyl.
The aryl group is preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.
The heterocyclic group represents a 5-membered to 7-membered, monocyclic or condensed, aromatic or non-aromatic heterocyclic group, such as a pyridine ring group, a pyrimidine ring group, a triazine ring group, a thiazole ring group, Benzothiazole ring group, oxazole ring group, benzoxazole ring group, imidazole ring group, benzimidazole ring group, pyrazole ring group, indazole ring group, indole ring group, purine ring group, quinoline ring group, isoquinoline ring group, quinazoline ring group Etc.

Hereinafter, from a compound in which the reducing group is a group represented by the general formulas (B ₁ ) to (B ₃ ) and a group derived from any of reductones, phenols, naphthols, phenylenediamines, and pyrazolidones. Although the preferable specific example (Exemplary compound (I-1)-(I-71)) of the compound chosen is shown, the scope of the present invention is not limited to these.

  The above compounds can be synthesized with reference to the methods described in JP-A-61-90153, JP-A-4-368935 and publications cited therein. However, there are roughly two synthesis routes for synthesizing a compound having a hydroxylamine partial structure, and the first is a route in which a divalent linking group portion is reacted with an adsorbing group and then a hydroxyamine portion is reacted. The second is a route in which a divalent linking group portion is reacted with a hydroxylamine portion and then an adsorbing group is reacted. The former is preferred. Any of them can be synthesized by a general organic synthesis technique.

The synthesis method of compound example (I-10) of this invention is described as a specific example below.
A synthesis scheme and a synthesis recipe are shown below.

(Synthesis of Intermediate A)
A mixture of 3,2.4 g of 2,5-dihydroxybenzoic acid, 35.0 g of p-nitrophenol, 400 ml of acetonitrile and 2 ml of DMF was heated to reflux, and 23 ml of thionyl chloride was carefully added dropwise little by little, and then heated to reflux for 1 hour. . When cooled to room temperature, a slightly viscous solid precipitated, and the filtered crude crystals were used as they were in the next step. Yield 55g.
(Synthesis of Intermediate B)
(Intermediate A) 55 g and 2-aminopyridine 56.5 g were heated at 120 ° C. for 6 hours with stirring. The solid component obtained after cooling to room temperature was filtered and washed with acetonitrile. Yield 41.4g.
(Synthesis of Compound Example (I-10))
(Intermediate B) A mixture of 4.6 g and methyl iodide 10 ml was stirred at 35 ° C. for 5 hours. After cooling the reaction solution to room temperature, the precipitated crystals were filtered and washed with acetonitrile. Yield 7.0g.

<Addition method>
The compound of the general formula (AR) in the present invention may be used at any time during the preparation of the silver halide emulsion and during the preparation of the coating solution. For example, at the time of particle formation, desalting step, chemical sensitization, and before coating. Moreover, it can also add in several steps in these processes. The addition timing is preferably from the end of particle formation to before the desalting step, at the time of chemical sensitization (immediately after the start of chemical sensitization to immediately after completion), and before application, more preferably at the time of chemical sensitization and before application.

  The compound of the general formula (AR) in the present invention may be added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof, or may be added as an emulsified dispersion or a solid fine particle dispersion. .

<Addition amount>
The compound of the general formula (AR) in the present invention is preferably added to the image forming layer, but may be added to the adjacent protective layer or intermediate layer together with the image forming layer and diffused during coating.
The compound of the general formula (AR) in the present invention is 1 × 10 ⁻⁹ mol to 5 × 10 ⁻² mol, more preferably 1 × 10 ⁻⁸ mol to 1 × 10 ⁻² mol, per mol of silver halide. Used in proportions.

Although the details of the quaternary salt adsorbing group and reducing group of the present invention are high in sensitivity, storage fog, sensitivity in short-time development, and image storability are unknown, the inventors speculate as follows: is doing.
Conventionally, the compound having a mercapto adsorbing group and a reducing group used in Examples such as JP-A No. 2004-184430 is a compound that adsorbs to silver, and thus reduces the silver halide during storage and deteriorates the storage fog. Is thought to have at the same time. On the other hand, the compound having a quaternary salt adsorbing group and a reducing group of the present invention is considered to be adsorbed to the halogen of silver halide because it has a positive charge. Therefore, since it is not near the silver halide silver, it is considered that the silver halide is reduced by its own reducing group and does not generate a nucleus. The effect of the present invention is remarkably exhibited when performing color sensitization that is considered to be adsorbed to the same halogen, or the effect of the present invention is significant for silver halides in which the Ag plane and the I plane are clearly present, such as AgI. It can be understood from what appears in Similarly, when a large amount of a mercapto compound is added, the development is suppressed, so that the compound of the present invention that adsorbs to the halogen does not cover the silver that forms the filament at the time of development. I understood that high sensitivity would be obtained.

(Photosensitive silver halide)
1) Halogen composition Although there is no restriction | limiting in particular in the photosensitive silver halide used for this invention, The thing of a silver iodide content rate as high as 40 mol% or more is one of the preferable forms of this invention. More preferably, it is 80 mol% or more. The rest is not particularly limited and can be selected from silver chloride, silver bromide, or organic silver salts such as silver thiocyanate and silver phosphate. Silver bromide and silver chloride are particularly preferred.

The distribution of the halogen composition in the grain may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can also be preferably used.
A preferable structure is a 2- to 5-fold structure, and more preferably 2- to 4-fold core / shell particles can be used. A core high silver iodide structure having a high silver iodide content in the core part or a shell high silver iodide structure having a high silver iodide content in the shell part can also be preferably used. Further, a technique of localizing silver chloride or silver bromide as an epitaxial portion on the surface of the grain can be used.

  In the case where the present invention is silver iodide, an arbitrary β phase and γ phase content can be taken. The β phase refers to a high silver iodide structure having a hexagonal wurtzite structure, and the γ phase refers to a high silver iodide structure having a cubic zinc blend structure. The β phase content mentioned here is C.I. R. It is determined using the method proposed by Berry. This method is determined based on the peak ratio of the silver iodide β phase (100), (101), (002) and the γ phase (111) in the powder X-ray diffraction method. Physical Review, Volume 161, No. 3, p. Reference may be made to 848-851 (1967).

2) Grain size The silver halide used in the present invention is not particularly limited, but a sufficiently large grain size necessary to achieve high sensitivity can be selected. In the present invention, the preferred average sphere equivalent diameter of silver halide is 0.1 μm or more and 10.0 μm or less, more preferably 0.2 μm or more and 5.0 μm or less, and 0.3 μm or more and 3.0 μm or less. Most preferably it is. The equivalent sphere diameter here means the diameter of a sphere having the same volume as the volume of one silver halide grain. As a measuring method, it can obtain | require by calculating | requiring the particle | grain volume from each projected area and thickness observed with the electron microscope, and converting into the sphere of the same volume as the volume.

3) Coating amount Generally, in the case of a photothermographic material in which silver halide remains as it is after heat development, increasing the silver halide coating amount lowers the transparency of the film and is undesirable from the viewpoint of image quality. Despite the request, it was low and limited. However, in the case of the present invention, the haze of the film due to silver halide can also be reduced by heat development, so that more silver halide can be applied. In this invention, it is more preferable that they are 0.5 mol% or more and 100 mol% or less with respect to 1 mol of silver of a nonphotosensitive organic silver salt, Preferably they are 5 mol% or more and 50 mol% or less.

4) Tabular grain shape and preparation method The shape of the silver halide grains in the present invention is not particularly limited, but tabular grains are preferably used in order to obtain higher sensitivity. The tabular grains preferably have an aspect ratio of 2 or more, more preferably 2 or more and 100 or less, and still more preferably 5 or more and 50 or less. The aspect ratio is a value obtained by dividing the equivalent circle diameter of the projected area of each particle by the thickness. Here, the equivalent-circle diameter of the projected area means the diameter of a circle having the same area as the projected area of one silver halide grain. As a measuring method, it can obtain | require by calculating | requiring the particle | grain area from each projected area observed with the electron microscope, and converting into the circle of the same area as the area. The projected area equivalent diameter of silver halide is preferably 0.2 μm to 20.0 μm, more preferably 0.4 μm to 20 μm, and further preferably 0.5 μm to 15 μm.
The grain thickness of the photosensitive silver halide used in the present invention is preferably 0.3 μm or less, more preferably 0.2 μm or less, and still more preferably 0.15 μm or less. The grain thickness of silver halide can be obtained by various methods. For example, there is a method of obtaining a circle equivalent diameter and thickness of the projected area of each grain by taking a transmission electron micrograph by a replica method. In this case, the thickness is calculated from the length of the shadow of the replica. The thickness of the epi tabular grains cannot be calculated simply from the length of the shadow of the replica because of epitaxial deposition. However, it can be calculated by measuring the length of the shadow of the replica before epitaxial deposition. Alternatively, even after epitaxial deposition, it can be easily obtained by cutting a sample coated with epitaxial tabular grains and taking an electron micrograph of the cross section.

  The silver halide having a high silver iodide content that can be used in the present invention can take a complicated form. L. JENKINS et al. J of Photo. Sci. Vol. No. 28 (1980), p164-FIG. 1, tabular grains are preferably used. Grains with rounded corners of silver halide grains can also be preferably used.

6) Heavy Metal The photosensitive silver halide grain in the invention is preferably doped with a different metal other than silver atoms. As the dissimilar metals other than silver atoms, metals or metal complexes of Group 3 to Group 13 of the Periodic Table (showing Groups 1 to 18) are preferable. As the central metal of the group 3 to group 13 metal or metal complex of the periodic table, rhodium, ruthenium, iridium and iron are preferable.
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 with ^respect to 1 mol of silver. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.

In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. The hexacyano metal complexes include [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, a hexacyano Fe complex is preferred.

  In addition to water, the hexacyano metal complex is miscible with a mixed solvent or gelatin with an appropriate organic solvent miscible with water (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.). Can be added.

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

  In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grain, the chalcogen sensitization of sulfur sensitization, selenium sensitization and tellurium sensitization is completed after the addition of the aqueous silver nitrate solution used for grain formation. It is added directly before the completion of the preparation step before the chemical sensitization step for performing noble metal sensitization such as sensitization and gold sensitization, during the washing step, during the dispersion step, or before the chemical sensitization step. In order to prevent the silver halide fine grains from growing, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add it before the completion of the preparation step.

Further, regarding a metal atom (for example, [Fe (CN) ₆ ] ⁴⁻ ), a silver halide emulsion desalting method and a chemical sensitization method that can be contained in the silver halide grains used in the present invention, JP-A-11-11 No. 84574, paragraph numbers 0046 to 0050, JP-A No. 11-65021, paragraph numbers 0025 to 0031, and JP-A No. 11-119374, paragraph numbers 0242 to 0250.

7) Gelatin As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. In order to satisfactorily maintain the dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution, 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 dispersion after desalting, but are preferably used at the time of dispersion after desalting.

8) Chemical sensitization The photosensitive silver halide used in the present invention may be non-chemically sensitized, but chemically sensitized by at least one of a chalcogen sensitization method, a gold sensitization method, and a reduction sensitization method. Is preferred. Examples of the chalcogen sensitizing method include a sulfur sensitizing method, a selenium sensitizing method, and a tellurium sensitizing method.

In sulfur sensitization, unstable sulfur compounds are used. The unstable sulfur compounds described in Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure, Vol. 307, No. 307105 can be used.
Specifically, thiosulfate (for example, hypo), thioureas (for example, diphenylthiourea, triethylthiourea, N-ethyl-N ′-(4-methyl-2-thiazolyl) thiourea, carboxymethyltrimethylthiourea), thioamides (Eg, thioacetamide), rhodanines (eg, diethyl rhodanine, 5-benzylidene-N-ethyl rhodanine), phosphine sulfides (eg, trimethylphosphine sulfide), thiohydantoins, 4-oxo-oxazolidin-2 Known sulfur compounds such as thiones, disulfides or polysulfides (eg, dimorpholine disulfide, cystine, lenthionine (1,2,3,5,6-pentathiepane)), polythionates, elemental sulfur and active gelatin Also used Can. Particularly preferred are thiosulfates, thioureas and rhodanines.

  In the selenium sensitization, unstable selenium compounds are used, and Japanese Patent Publication Nos. 43-13489, 44-15748, JP-A-4-25832, 4-109340, 4-271341, and 5-40324. 5-11385, JP-A-6-51415, 6-175258, 6-180478, 6-208186, 6-208184, 6-317867, 7-92599, Selenium compounds described in JP-A-7-98483 and JP-A-7-140579 can be used.

Specifically, colloidal metal selenium, selenoureas (eg, N, N-dimethylselenourea, trifluoromethylcarbonyl-trimethylselenourea, acetyl-trimethylselenourea), selenoamides (eg, selenoamide, N, N-diethyl) Phenylselenoamide), phosphine selenides (eg, triphenylphosphine selenide, pentafluorophenyl-triphenylphosphine selenide), selenophosphates (eg, tri-p-tolylselenophosphate, tri-n) -Butylselenophosphate), selenoketones (for example, selenobenzophenone), isoselenocyanates, selenocarboxylic acids, selenoesters, diacyl selenides and the like may be used.
Furthermore, non-labile selenium compounds described in JP-B Nos. 46-4553 and 52-34492, such as selenite, selenocyanate, selenazoles, and selenides can also be used. In particular, phosphine selenides, selenoureas and selenocyanates are preferred.

  In tellurium sensitization, an unstable tellurium compound is used, and JP-A-4-224595, JP-A-4-271341, JP-A-4-3333043, JP-A-5-303157, JP-A-6-27573, JP-A-6-175258, The unstable tellurium described in JP-A-6-180478, JP-A-6-208186, JP-A-6-208184, JP-A-6-317867, JP-A-7-140579, JP-A-7-301879, JP-A-7-301880, etc. A compound can be used.

Specifically, phosphine tellurides (for example, butyl-diisopropylphosphine telluride, tributylphosphine telluride, tributoxyphosphine telluride, ethoxydiphenylphosphine telluride), diacyl (di) tellurides ( For example, bis (diphenylcarbamoyl) ditelluride, bis (N-phenyl-N-methylcarbamoyl) ditelluride, bis (N-phenyl-N-methylcarbamoyl) telluride, bis (N-phenyl-N-benzylcarbamoyl) telluride, bis (ethoxycarbonyl) Telluride), telluroureas (for example, N, N′-dimethylethylenetellurourea, N, N′-diphenylethylenetellurourea) telluramides, telluroesters and the like may be used.
In particular, diacyl (di) tellurides and phosphine tellurides are preferable. Particularly, the compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, the general formula (II) in JP-A-5-313284, Compounds represented by (III) and (IV) are more preferred.

  Particularly, in the chalcogen sensitization of the present invention, selenium sensitization and tellurium sensitization are preferable, and tellurium sensitization is particularly preferable.

  In gold sensitization, P.I. Gold sensitizers described by Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure 307, No. 307105 can be used. Specifically, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide and the like, in addition to these, U.S. Pat. Nos. 2,642,361, 5,049,484, 5,049,485, 5,169,751, Gold compounds described in 5252455, Belgian Patent No. 691857 and the like can also be used. P. Using platinum, palladium, iridium, etc. other than gold described in Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure magazine, 307, 307105 You can also.

  Although gold sensitization can be used alone, it is preferably used in combination with the chalcogen sensitization described above. Specifically, gold sulfur sensitization, gold selenium sensitization, gold tellurium sensitization, gold sulfur selenium sensitization, gold sulfur tellurium sensitization, gold selenium tellurium sensitization, and gold sulfur selenium tellurium sensitization.

  In the present invention, chemical sensitization can be performed at any time after particle formation and before coating. After desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, (3) spectral After sensitization, there may be (4) immediately before application.

The amount of chalcogen sensitizer used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, and the like, but is 10 ^-8 to 10 ^-1 mol, preferably 10 ^-7 to 1 mol per mol of silver halide. About 10 ^-2 mol is used.
Similarly, the amount of the gold sensitizer used in the present invention varies depending on various conditions, but as a guide, it is 10 ⁻⁷ mol to 10 ⁻² mol, more preferably 10 ⁻⁶ mol to 5 mol per mol of silver halide. × 10 ^-3 mol. The environmental conditions for chemically sensitizing this emulsion can be selected under any conditions, but the pAg is 8 or less, preferably 7.0 or less to 6.5 or less, particularly 6.0 or less, and the pAg is 1.5 or less. Above, preferably 2.0 or more, particularly preferably 2.5 or more, pH is 3 to 10, preferably 4 to 9, temperature is 20 ° C. to 95 ° C., preferably 25 ° C. to 80 ° C. Degree.

In the present invention, reduction sensitization not included in the present invention can be used in combination with chalcogen sensitization and gold sensitization. In particular, it is preferably used in combination with chalcogen sensitization. As specific compounds for the reduction sensitization, ascorbic acid, thiourea dioxide, and dimethylamine borane are preferable. In addition, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. It is preferable to use it. The reduction sensitizer may be added at any stage in the photosensitive emulsion production process from crystal growth to the preparation process immediately before coating. Further, reduction sensitization is also preferable by ripening while maintaining the pH of the emulsion at 8 or more or pAg at 4 or less, and reduction sensitization is performed by introducing a single addition portion of silver ions during grain formation. Is also preferable.
The amount of the reduction sensitizer, likewise may vary depending on various conditions, per mol of silver halide 10 ^-7 mol to 10 ^-1 mol as a guide, and more preferably 10 ^-6 mol to 5 × 10 ^{- 2} moles.

A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method shown in European Patent Publication No. 293,917.
The photosensitive silver halide grains in the invention are preferably chemically sensitized by at least one of gold sensitization and chalcogen sensitization from the viewpoint of designing a high-sensitivity photothermographic material.

9) Compound in which 1-electron oxidant produced by 1-electron oxidation can emit 1 electron or more electrons In the photothermographic material of the present invention, 1-electron oxidant produced by 1-electron oxidation is 1 electron or It is preferable to contain a compound capable of emitting more electrons. The compound can be used alone or in combination with the above-described various chemical sensitizers, and can increase the sensitivity of silver halide.

The one-electron oxidant produced by one-electron oxidation contained in the light-sensitive material of the present invention is a compound selected from the following types 1 and 2 that can emit one or more electrons.
(Type 1)
A compound in which a one-electron oxidant produced by one-electron oxidation can further emit one or more electrons with a subsequent bond cleavage reaction.
(Type 2)
A compound capable of emitting one or more electrons after a one-electron oxidant produced by one-electron oxidation undergoes a subsequent bond formation reaction.

First, the compound of type 1 will be described.
JP-A-9-211769 (specific example: 28-) is a compound that is a type 1 compound, and a one-electron oxidant produced by one-electron oxidation can further emit one electron with a subsequent bond cleavage reaction. Compounds PMT-1 to S-37 described in Table E and Table F on page 32), JP-A-9-211774, JP-A-11-95355 (specific examples: compounds INV1 to 36), JP2001-500996 (Specific examples: Compounds 1-74, 80-87, 92-122), US Pat. No. 5,747,235, US Pat. No. 5,747,236, European Patent 786692A1 (Specific examples: Compounds INV 1-35), "One-photon two-electron sensitizer" or "deprotonated electron" described in patents such as European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051 Compound called Azukazo sensitizers "it can be mentioned. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

Further, as a compound of type 1 that can be emitted by one-electron oxidant formed by one-electron oxidation and further undergoing bond cleavage reaction, one or more electrons can be emitted from the general formula (1) ( General formula (1) described in JP-A-2003-114487), general formula (2) (synonymous with general formula (2) described in JP-A-2003-114487), general formula (3) General formula (1) described in 2003-114488), general formula (4) (synonymous with general formula (2) described in Japanese Patent Application Laid-Open No. 2003-114488), general formula (5) (Japanese Patent Application Laid-Open No. 2003-114488). 114488 (synonymous with general formula (3)), general formula (6) (synonymous with general formula (1) described in JP-A-2003-75950), and general formula (7) (JP-A-2003-75950). Synonymous with general formula (2) described in , General formula (8) (synonymous with general formula (1) described in Japanese Patent Application No. 2003-25886) or chemical reaction formula (1) (chemical reaction formula (1) described in Japanese Patent Application No. 2003-33446) And the compound represented by the general formula (9) (synonymous with the general formula (3) described in Japanese Patent Application No. 2003-33446).
The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

一般式（６） 一般式（７）

General formula (6) General formula (7)

In the formula, RED ₁ and RED ₂ represent a reducing group. R ₁ is a non-metallic atomic group capable of forming a cyclic structure corresponding to a tetrahydro form of a 5-membered or 6-membered aromatic ring (including an aromatic heterocycle) or an octahydro form together with carbon atom (C) and RED _1. To express. R ₂ represents a hydrogen atom or a substituent. When a plurality of R ₂ are present in the same molecule, these may be the same or different. L ₁ represents a leaving group. ED represents an electron donating group. Z ₁ represents an atomic group capable of forming a 6-membered ring with a nitrogen atom and two carbon atoms of a benzene ring. X ₁ represents a substituent, and m 1 represents an integer of 0 to 3. Z ₂ represents —CR ₁₁ R ₁₂ —, —NR ₁₃ —, or —O—. R ₁₁ and R ₁₂ each independently represents a hydrogen atom or a substituent. R ₁₃ represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. X ₁ represents an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylamino group, an arylamino group, or a heterocyclic amino group. L ₂ represents a carboxy group or a salt thereof, or a hydrogen atom. X ₂ represents a group which forms a 5-membered heterocycle with C═C.
Y ₂ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation.

Next, the type 2 compound will be described.
As a compound that can be emitted by one-electron oxidant generated by one-electron oxidation with a type 2 compound and further undergoing a bond formation reaction, one or more electrons can be emitted from the general formula (10) The reaction represented by the general formula (1) described in 2003-140287) and the chemical reaction formula (1) (synonymous with the chemical reaction formula (1) described in Japanese Patent Application No. 2003-33446) may occur. And a compound represented by the general formula (11) (synonymous with the general formula (2) described in Japanese Patent Application No. 2003-33446). The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the above formula, X represents a reducing group that is one-electron oxidized. Y reacts with a one-electron oxidant produced by one-electron oxidation of X to form a new bond, a carbon-carbon double bond site, a carbon-carbon triple bond site, an aromatic group site, or a benzo The reactive group containing the non-aromatic heterocyclic part of a condensed ring is represented. L ₂ represents a linking group for linking X and Y. R ₂ represents a hydrogen atom or a substituent. When a plurality of R ₂ are present in the same molecule, these may be the same or different.
X ₂ represents a group which forms a 5-membered heterocycle with C═C. Y ₂ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation.

  Of the compounds of types 1 and 2, “a compound having an adsorptive group to silver halide in the molecule” or “a compound having a partial structure of a spectral sensitizing dye in the molecule” is preferable. Typical examples of the adsorptive group to silver halide include those described in JP-A No. 2003-156823, page 16, right line 1 to page 17, right line 12. The partial structure of the spectral sensitizing dye is a structure described on page 17, right line 34 to page 18, left line 6 of the same specification.

  More preferably, the compound of type 1 or 2 is “a compound having at least one adsorptive group to silver halide in the molecule”. More preferred is “a compound having two or more adsorptive groups to silver halide in the same molecule”. When two or more adsorptive groups are present in a single molecule, these adsorptive groups may be the same or different.

  The adsorptive group is preferably a mercapto-substituted nitrogen-containing heterocyclic group (for example, 2-mercaptothiadiazole group, 3-mercapto-1,2,4-triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4). -Oxadiazole group, 2-mercaptobenzoxazole group, 2-mercaptobenzthiazole group, 1,5-dimethyl-1,2,4-triazolium-3-thiolate group, etc.) or imino silver (> NAg) And a nitrogen-containing heterocyclic group having a —NH— group as a heterocyclic partial structure (for example, a benzotriazole group, a benzimidazole group, an indazole group, etc.). Particularly preferred are 5-mercaptotetrazole group, 3-mercapto-1,2,4-triazole group, and benzotriazole group, most preferred are 3-mercapto-1,2,4-triazole group, and 5 -Mercaptotetrazole group.

  It is also particularly preferred that the adsorptive group has two or more mercapto groups as a partial structure in the molecule. Here, the mercapto group (—SH) may be a thione group if it can be tautomerized. Preferred examples of the adsorptive group having two or more mercapto groups as a partial structure (such as a dimercapto-substituted nitrogen-containing telocyclic group) include 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3, A 5-dimercapto-1,2,4-triazole group may be mentioned.

A quaternary salt structure of nitrogen or phosphorus is also preferably used as the adsorptive group. Specific examples of the quaternary salt structure of nitrogen include an ammonio group (such as a trialkylammonio group, a dialkylaryl (or heteroaryl) ammonio group, an alkyldiaryl (or heteroaryl) ammonio group) or a quaternized nitrogen atom. A group containing a nitrogen-containing heterocyclic group containing
The quaternary salt structure of phosphorus includes a phosphonio group (such as a trialkyl phosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group). Is mentioned.
More preferably, a quaternary salt structure of nitrogen is used, and a 5-membered or 6-membered nitrogen-containing aromatic heterocyclic group containing a quaternized nitrogen atom is more preferably used. Particularly preferably, a pyridinio group, a quinolinio group, or an isoquinolinio group is used. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent.

Examples of counter anions of quaternary salts include halogen ions, carboxylate ions, sulfonate ions, sulfate ions, perchlorate ions, carbonate ions, nitrate ions, BF ₄ ⁻ , PF ₆ ⁻ , Ph ₄ B ^{− and the} like. It is done. When a group having a negative charge in a carboxylate group or the like is present in the molecule, an inner salt may be formed together with the group. As the counter anion not present in the molecule, a chlorine ion, a bromo ion or a methanesulfonate ion is particularly preferable.

  A preferred structure of the compound represented by type 1 or 2 having a quaternary salt structure of nitrogen or phosphorus as the adsorptive group is represented by the general formula (X).

In general formula (X), P and R each independently represent a quaternary salt structure of nitrogen or phosphorus that is not a partial structure of a sensitizing dye. Q ₁ and Q ₂ each independently represent a linking group, specifically a single bond, an alkylene group, an arylene group, a heterocyclic group, —O—, —S—, —NR _N —, —C (═O ) —, —SO ₂ —, —SO—, —P (═O) — each independently or a combination of these groups. Here, _RN represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. S is a residue obtained by removing one atom from a compound represented by type (1) or (2). i and j are integers of 1 or more, and i + j is selected from the range of 2-6. Preferably, i is 1 to 3, and j is 1 to 2, more preferably i is 1 or 2, and j is 1, and particularly preferably i is 1 and j is 1. The compound represented by the general formula (X) preferably has a total carbon number of 10 to 100. More preferably, it is 10-70, More preferably, it is 11-60, Most preferably, it is 12-50.

The type 1 and type 2 compounds in the present invention may be used at any time during the preparation of the photosensitive silver halide emulsion and during the process of producing the photothermographic material. For example, at the time of photosensitive silver halide grain formation, desalting step, chemical sensitization, before coating.
Moreover, it can also add in several steps in these processes. The addition position is preferably from the end of formation of the photosensitive silver halide grains to before the desalting step, at the time of chemical sensitization (immediately after the start of chemical sensitization to immediately after completion), and before coating, more preferably from the time of chemical sensitization Until before mixing with the non-photosensitive organic silver salt.

  The compounds of type 1 and type 2 in the present invention are preferably added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. When the compound is dissolved in water, the compound having higher solubility when the pH is increased or decreased may be dissolved at a higher or lower pH and added.

The compounds of type 1 and type 2 in the present invention are preferably used in an emulsion layer containing a photosensitive silver halide and a non-photosensitive organic silver salt, but the photosensitive silver halide and the non-photosensitive organic silver salt are used. It may be added to the protective layer and the intermediate layer together with the emulsion layer to be contained and diffused during coating.
The timing of addition of the compound of the present invention is preferably before or after the sensitizing dye, and is preferably 1 × 10 ^{−9 to} 5 × 10 ⁻¹ mol, more preferably 1 × 10 ^{−8 to} 5 per mol of silver halide. X10 ^-2 mol in a silver halide emulsion layer.

  Specific examples of type 1 and type 2 compounds in the present invention are given below, but the present invention is not limited to these.

10) Sensitizing dye Another preferred embodiment in the present invention is that the silver halide is spectrally sensitized.
As a sensitizing dye that can be applied to the present invention, it can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and has a spectral sensitivity suitable for the spectral characteristics of the exposure light source. The dye can be advantageously selected.
The photothermographic material of the present invention is preferably spectrally sensitized so as to have a spectral sensitivity peak at 600 nm to 900 nm, or 300 nm to 500 nm. Regarding the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A No. 11-65021, compounds represented by formula (II) of JP-A No. 10-186572, and formulas (I of JP-A No. 11-119374) ) And the dye described in Example 5 of U.S. Pat. Nos. 5,510,236 and 3,871,887, JP-A-2-96131, JP-A-59-48753. No. 19, page 38 to line 20, page 35 of European Patent Publication No. 0803764A1, JP 2001-272747, JP 2001-290238, JP 2002-23306, etc. It is described in. These sensitizing dyes may be used alone or in combination of two or more.

The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with the sensitivity and the fogging performance, but is preferably 10 ⁻⁶ to 1 mol, more preferably 1 mol per mol of silver halide in the photosensitive layer. Is 10 ⁻⁴ to 10 ⁻¹ mol.

  In the present invention, a supersensitizer can be used to improve spectral sensitization efficiency. As the supersensitizer used in the present invention, European Patent Publication No. 587,338, US Pat. Nos. 3,877,943, 4,873,184, JP-A-5-341432, 11- 109547, 10-111543, etc. are mentioned.

11) Combined use of silver halide The photosensitive silver halide emulsion in the photothermographic material used in the present invention may be one kind or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions). , Different crystal habits, different chemical sensitization conditions). The gradation can be adjusted by using a plurality of types of photosensitive silver halides having different sensitivities. As techniques relating to these, there are JP-A-57-119341, 53-106125, 47-3929, 48-55730, 46-5187, 50-73627, 57-150841, and the like. Can be mentioned. The sensitivity difference is preferably 0.2 log E or more for each emulsion.

12) Mixing of silver halide and organic silver salt It is particularly preferred that the photosensitive silver halide grains of the present invention are formed in the absence of non-photosensitive organic silver salt and chemically sensitized. This is because sufficient sensitivity may not be achieved by the method of forming silver halide by adding a halogenating agent to the organic silver salt.
As a method of mixing silver halide and organic silver salt, separately prepared photosensitive silver halide and organic silver salt using a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc. Alternatively, there may be mentioned a method of preparing an organic silver salt by mixing photosensitive silver halide which has been prepared at any timing during the preparation of the organic silver salt. In any method, the effects of the present invention can be preferably obtained.

13) Mixing of silver halide into coating solution The preferred addition time of the silver halide of the present invention to the image forming layer coating solution is from 180 minutes before application, preferably from 60 minutes to 10 seconds before application. However, the mixing method and mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is the desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method of using a static mixer or the like described in Chapter 8 of Nienow's Koji Takahashi's “Liquid Mixing Technology” (published by Nikkan Kogyo Shimbun, 1989).

(Organic silver salt)
The non-photosensitive organic silver salt used in the present invention is relatively stable to light, but when heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide and a reducing agent. A silver salt that forms a silver image. The organic silver salt may be any organic material containing a source capable of reducing silver ions. As for such non-photosensitive organic silver salt, paragraph numbers 0048 to 0049 of JP-A-10-62899, page 18 line 24 to page 19 line 37 of European Patent Publication No. 0803764A1, European Patent Publication. No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, and the like. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids (having 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Preferable examples of the organic silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and a mixture thereof. In the present invention, among these organic silver salts, it is preferable to use organic acid silver having a silver behenate content of 50 mol% to 100 mol%. In particular, the silver behenate content is preferably 75 mol% or more and 98 mol% or less.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be a needle shape, a rod shape, a flat plate shape, or a flake shape.
In the present invention, scaly organic silver salts are preferred. In the present specification, the scaly organic silver salt is defined as follows. The organic silver salt is observed with an electron microscope, the shape of the organic silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (even though c is the same as b) Good)), and calculate with the shorter numbers a and b, and find x as follows.
x = b / a

  In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 15 ≧ x (average) ≧ 1.5. Incidentally, the needle shape is 1 ≦ x (average) <1.5.

  In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.3 μm or less, and more preferably 0.1 μm or more and 0.23 μm or less. The average of c / b is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and particularly preferably 1 or more and 2 or less.

The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. Indicates the following.
The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method of obtaining from the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, it is obtained from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to the temporal change of the fluctuation of the scattered light. Can do.

  Known methods and the like can be applied to the production and dispersion method of the organic acid silver used in the present invention. For example, Japanese Patent Application Laid-Open No. 10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0968212A1, Japanese Patent Application Laid-Open No. 11-349591, Japanese Patent Application Laid-Open No. 2000-7683, Japanese Patent Application Laid-Open No. 2000-163711, and Japanese Patent Application Laid-Open No. 2001-163827. JP-A-2001-163889-90, JP-A-11-203413, JP-A-2001-188313, JP-A-2001-83552, JP-A-2002-6442, JP-A-2002-31870, JP-A-2000-214155, JP-A-2000-214155. Reference can be made to 2002-6442.

  In the present invention, an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion can be mixed to produce a photosensitive material. Mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present invention can be used in a desired amount, preferably 0.1g / m ² ~5g / m ² as silver amount, more preferably from 1 to 3 g / m ^2. Particularly preferably ^{1.2g / m 2 ~2.5g / m 2} .

(Reducing agent)
The photothermographic material of the present invention contains a reducing agent for organic silver salt. The reducing agent may be any substance (preferably an organic substance) that can reduce silver ions to metallic silver. Examples of the reducing agent include JP-A No. 11-65021, paragraph numbers 0043 to 0045, European Patent No. 0803764, p. 7, lines 34-p. 18th and 12th lines.

  A preferable reducing agent used in the present invention is a so-called hindered phenol reducing agent having a substituent at the ortho position of the phenolic hydroxyl group, or a bisphenol reducing agent. Particularly preferred are compounds represented by the following general formula (R).

Formula (R)

In the general formula (R), R ¹¹ and R ¹¹ ′ each independently represents an alkyl group having 1 to 20 carbon atoms. R ¹² and R ¹² ′ each independently represent a hydrogen atom or a substituent that can be substituted on a benzene ring. L represents an —S— group or a —CHR ¹³ — group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

Each substituent will be described in detail.
1) R ¹¹ and R ¹¹ '
R ¹¹ and R ¹¹ ′ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and the substituent of the alkyl group is not particularly limited, but is preferably an aryl group, a hydroxy group, Examples thereof 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.

2) R ¹² and R ¹² ', X ¹ and X ¹ '
R ¹² and R ¹² ′ each independently represent a hydrogen atom or a group capable of substituting for a benzene ring.
X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group capable of substituting for a benzene ring. Preferred examples of the group that can be substituted on the benzene ring include an alkyl group, an aryl group, a halogen atom, an alkoxy group, and an acylamino group.

3) L
L represents an —S— group or a —CHR ¹³ — group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent.
Specific examples of the unsubstituted alkyl group represented by R ¹³ 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. can give.

Examples of the substituent of the alkyl group are the same as the substituent of R ¹¹ , and are a halogen atom, alkoxy group, alkylthio group, aryloxy group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, oxycarbonyl group, Examples thereof include a carbamoyl group and a sulfamoyl group.

4) Preferred substituents R ¹¹ and R ¹¹ ′ are preferably secondary or tertiary alkyl groups having 3 to 15 carbon atoms, specifically, isopropyl group, isobutyl group, t-butyl group, t-amyl group. , T-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like. R ¹¹ and R ¹¹ ′ are more preferably a tertiary alkyl group having 4 to 12 carbon atoms, and among them, a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a t-butyl group is most preferable. .

R ¹² and R ¹² ′ are preferably an alkyl group having 1 to 20 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, a cyclohexyl group. Group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, methoxyethyl group and the like. More preferred are methyl group, ethyl group, propyl group, isopropyl group and t-butyl group.

X ¹ and X ¹ ′ are preferably a hydrogen atom, a halogen atom, or an alkyl group, and more preferably a hydrogen atom.

L is preferably a —CHR ¹³ — group.

R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and the alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4,4-trimethylpentyl group. Particularly preferred as R ¹³ is a hydrogen atom, a methyl group, a propyl group or an isopropyl group.

When R ¹³ is a hydrogen atom, R ¹² and R ¹² ′ are preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group.

When R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, R ¹² and R ¹² ′ are preferably methyl groups. The primary or secondary alkyl group having 1 to 8 carbon atoms of R ¹³ is more preferably a methyl group, an ethyl group, a propyl group or an isopropyl group, and further preferably a methyl group, an ethyl group or a propyl group.

When all of R ¹¹ , R ¹¹ ′ and R ¹² , R ¹² ′ are methyl groups, R ¹³ is preferably a secondary alkyl group. In this case, the secondary alkyl group of R ¹³ is preferably an isopropyl group, an isobutyl group, or a 1-ethylpentyl group, and more preferably an isopropyl group.

The reducing agent has various heat development performances depending on the combination of R ¹¹ , R ¹¹ ′, R ¹² and R ¹² ′, and R ¹³ . Since these heat development performances can be prepared by using two or more kinds of reducing agents in combination at various mixing ratios, it is preferable to use two or more kinds of reducing agents in combination depending on the purpose.

    Specific examples of the compound represented by the general formula (R) of the present invention are shown below, but the present invention is not limited thereto.

The addition amount of the reducing agent is preferably a ^{0.01g / m 2 ~5.0g / m 2} , more preferably from ^{0.1g / m 2 ~3.0g / m 2} , the image forming 5 mol% to 50 mol% is preferably contained with respect to 1 mol of silver on the surface having the layer, and more preferably 10 mol% to 40 mol%.

  The reducing agent of the present invention can be added to an image forming layer containing an organic silver salt and a photosensitive silver halide and its adjacent layer, but it is more preferably contained in the image forming layer.

  The reducing agent of the present invention may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.

  Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. The method of producing is mentioned.

  In addition, as the solid fine particle dispersion method, there is a method in which a reducing agent is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill or an ultrasonic wave to produce a solid dispersion. Can be mentioned. A dispersion method using a sand mill is preferable. In this case, a protective colloid (for example, polyvinyl alcohol) or 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).

  Particularly preferable is a solid particle dispersion method of a reducing agent, and it is preferable to add fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1 μm. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

(Development accelerator)
In the photothermographic material of the present invention, a sulfonamide phenol compound represented by the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234, or the like as a development accelerator, Hindered phenol compounds represented by general formula (II) described in JP-A No. 2001-92075, general formula (I) described in JP-A No. 10-62895, JP-A No. 11-15116 and the like, A hydrazine-based compound represented by general formula (D) of JP-A No. 2002-156727 or general formula (1) described in JP-A No. 2002-278017, and described in JP-A No. 2001-264929 A phenolic or naphtholic compound represented by the general formula (2) is preferably used. These development accelerators are used in the range of 0.1 to 20 mol% with respect to the reducing agent, preferably in the range of 0.5 to 10 mol%, more preferably in the range of 1 to 5 mol%. The introduction method to the light-sensitive material includes the same method as the reducing agent, but it is particularly preferable to add as a solid dispersion or an emulsified dispersion. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high-boiling solvent that is solid at room temperature and a low-boiling auxiliary solvent, or as a so-called oilless emulsified dispersion that does not use a high-boiling solvent. It is preferable to add.
In the present invention, among the above development accelerators, hydrazine compounds represented by the general formula (D) described in JP-A No. 2002-156727 and those described in JP-A No. 2001-264929 are general. A phenol-based or naphthol-based compound represented by the formula (2) is more preferable.

Particularly preferred development accelerators of the present invention are compounds represented by the following general formulas (A-1) and (A-2).
Formula (A-1)
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, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, Or represents a sulfamoyl group.)

In the general formula (A-1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 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-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, thiophene ring, etc. are preferable, and these Also preferred are fused rings in which the rings are fused together.

  These rings may have a substituent, and when they have two or more substituents, these substituents may be the same or different. Examples of substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, arylsulfonamido groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, carbamoyl groups, sulfamoyl groups, cyano Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have substituents. Examples of preferred substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, aryls. Sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, and 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. For example, 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 Dodecyloxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl include 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 Q2 is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, dodecyl. Examples include oxycarbonyl 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, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples thereof include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q2 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, 3-dodecyl. Examples include oxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, and 4-dodecyloxyphenylsulfonyl.

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

Next, preferred range for the compound represented by formula (A-1) is to be described. Q ₁ is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, pyrimidine ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring. 1,2,4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, and these rings Is more preferably a ring fused with a benzene ring or an unsaturated heterocycle. Q ₂ is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on the nitrogen atom.

Formula (A-2)

In the general formula (A-2), R ₁ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate ester group. R ₃ and R ₄ each represents a group that can be substituted on the benzene ring mentioned in the example of the substituent of formula (A-1). R ₃ and R ₄ may be connected to each other to form a condensed ring.

R ₁ is preferably an alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an isopropyl group, a butyl group, a tert-octyl group, a cyclohexyl group, etc.), an acylamino group (for example, an acetylamino group, a benzoylamino group, a methyl group). Ureido group, 4-cyanophenylureido group, etc.), carbamoyl group (n-butylcarbamoyl group, N, N-diethylcarbamoyl group, phenylcarbamoyl group, 2-chlorophenylcarbamoyl group, 2,4-dichlorophenylcarbamoyl group, etc.) acylamino Groups (including ureido groups and urethane groups) are more preferred. R2 is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (for example, methoxy group, butoxy group, n-hexyloxy group, n-decyloxy group, cyclohexyloxy group, benzyloxy group, etc.), aryloxy A group (phenoxy group, naphthoxy group, etc.).

R ₃ is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, and most preferably a halogen atom. R ₄ is preferably a hydrogen atom, an alkyl group, or an acylamino group, and more preferably an alkyl group or an acylamino group. Examples of these preferable substituents are the same as those for R ₁ . When R ₄ is an acylamino group, R ₄ is preferably linked to R ₃ to form a carbostyryl ring.

In the general formula (A-2), when R ₃ and R ₄ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. The same substituent as the example of a substituent quoted by general formula (A-1) may couple | bond with the naphthalene ring. When general formula (A-2) is a naphthol-based compound, R ₁ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ₂ is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

  Hereinafter, although the preferable specific example of the development accelerator of this invention is given, this invention is not limited to these.

(Hydrogen bonding compound)
In the present invention, it is preferable to use a non-reducing compound having a group capable of forming a hydrogen bond with an aromatic hydroxyl group (—OH) of the reducing agent.

  Examples of the group capable of forming a hydrogen bond include phosphoryl group, sulfoxide group, sulfonyl group, carbonyl group, amide group, ester group, urethane group, ureido group, tertiary amino group, and nitrogen-containing aromatic group. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (however, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a urethane group. (However, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a ureido group (however, it does not have a> N—H group, N-Ra (Ra is a substituent other than H).)

  In the present invention, particularly preferred hydrogen bonding compounds are compounds represented by the following general formula (D).

Formula (D)

In the general formula (D), R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be substituted even if they are unsubstituted. You may have.

When R ²¹ to R ²³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group. Preferred examples of the substituent include an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, and a t-octyl group. Group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like.

Specific examples of the alkyl group represented by R ²¹ to R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, Examples thereof include 1-methylcyclohexyl group, benzyl group, phenethyl group, 2-phenoxypropyl group and the like.

  Examples of the aryl group include phenyl group, cresyl group, xylyl group, naphthyl group, 4-t-butylphenyl group, 4-t-octylphenyl group, 4-anisidyl group, and 3,5-dichlorophenyl group.

  Alkoxy groups include methoxy, ethoxy, butoxy, octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy, dodecyloxy, cyclohexyloxy, 4-methylcyclohexyloxy, benzyl An oxy group etc. are mentioned.

  Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, and a biphenyloxy group.

  Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. .

R ²¹ to R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In view of the effects of the present invention, at least one of R ²¹ to R ²³ is 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 ²¹ to R ²³ are the same group in that they can be obtained at low cost.

  Specific examples of the hydrogen bonding compound including the compound of the general formula (D) in the present invention are shown below, but the present invention is not limited thereto.

  Specific examples of the hydrogen bonding compound include those described in JP-A Nos. 2001-281793 and 2002-14438 in addition to the above.

  The hydrogen bonding compound of the present invention can be used in a light-sensitive material after being contained in a coating solution in the form of a solution, an emulsified dispersion, or a solid dispersed fine particle dispersion in the same manner as the reducing agent. The compound of the present invention forms a complex by a hydrogen bond with a compound having a phenolic hydroxyl group in a solution state. Depending on the combination of the reducing agent and the compound of the general formula (A) of the present invention, the compound of the present invention Can be separated.

  The use of the crystal powder isolated in this way as a solid dispersed fine particle dispersion is particularly preferable for obtaining stable performance. Further, a method in which the reducing agent and the hydrogen bonding compound of the present invention are mixed as a powder and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.

  The hydrogen bonding compound of the present invention is preferably used in the range of 1 to 200 mol%, more preferably in the range of 10 to 150 mol%, still more preferably in the range of 30 to 100 mol% with respect to the reducing agent. It is.

(binder)
The binder of the organic silver salt-containing layer of the present invention may be any polymer, suitable binders are transparent or translucent and generally colorless, natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, other films Forming media such as gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) , Poly (methyl methacrylic acid) s, poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, Poly (vinyl acetal) s (eg, poly (vinyl acetal) Marl) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s , Poly (olefin) s, cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

  In the present invention, the glass transition temperature of the binder of the layer containing the organic silver salt is preferably 10 ° C. or higher and 80 ° C. or lower, more preferably 20 ° C. to 70 ° C., and 23 ° C. or higher and 65 ° C. or lower. More preferably.

In this specification, Tg is calculated by the following formula.
1 / Tg = Σ (Xi / Tgi)

Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. 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. However, Σ is the sum from i = 1 to n.
As the transition temperature value (Tgi) of the homopolymer glass of each monomer, the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)) was adopted.

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

In the present invention, when the organic silver salt-containing layer is formed using a coating solution in which 30% by mass or more of the solvent is water and dried, the binder of the organic silver salt-containing layer is further an aqueous solvent ( When it is soluble or dispersible in an aqueous solvent), the performance is improved particularly when it is made of a latex of a polymer having an equilibrium moisture content of 2% by mass or less at 25 ° C. and 60% RH.
The most preferable form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and as such a preparation method, there is a method of purifying using a separation functional membrane after polymer synthesis.

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

The “equilibrium moisture content at 25 ° C. and 60% RH” is the following using the mass W1 of the polymer in a humidity-controlled equilibrium under an atmosphere of 25 ° C. and 60% RH and the mass W0 of the polymer in an absolutely dry state at 25 ° C. It can be expressed as
Equilibrium moisture content at 25 ° C. and 60% RH = [(W1-W0) / W0] × 100 (mass%)
For the definition and measurement method of the moisture content, for example, Polymer Engineering Course 14, Polymer Materials Testing Method (Edited by Polymer Society, Jinshokan) can be referred to.

  The equilibrium moisture content at 25 ° C. and 60% RH of the binder polymer of the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass. % To 1% by mass is desirable.

  The binder of the present invention is particularly preferably a polymer that can be dispersed in an aqueous solvent. Examples of the dispersed state include latex in which fine particles of water-insoluble hydrophobic polymer are dispersed and polymer molecules dispersed in a molecular state or forming micelles, and all are preferable. The average particle size of the dispersed particles is preferably in the range of about 1 nm to 50000 nm, more preferably about 5 nm to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  In the present invention, preferred embodiments of the polymer that can be dispersed in an aqueous solvent include acrylic polymers, poly (esters), rubbers (eg, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (acetic acid). Hydrophobic polymers such as vinyl), poly (vinylidene chloride) and poly (olefin) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer.

  These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. When the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable.

  Specific examples of the preferred polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

Latex of P-1; -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000, Tg 61 ° C.)
Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
P-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
Latex of P-4; -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C.)
Latex of P-5; -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
Latex of P-6; -St (70) -Bu (27) -IA (3)-(crosslinkability)
Latex of P-7; -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
P-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
Latex (crosslinkability) of P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-
P-10; Latex (molecular weight 80000) of -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-
P-11; latex of VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
Latex of P-12; -Et (90) -MAA (10)-(molecular weight 12000)
P-13; Latex of -St (70) -2EHA (27) -AA (3) (molecular weight 130000, Tg 43 ° C)
P-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33,000, Tg 47 ° C.)
Latex of P-15; -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
Latex of P-16; -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)

  The abbreviations for 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; itaconic acid.

The polymer latex described above is also commercially available, and the following polymers can be used. Examples of the acrylic polymer include Sebian A-4635, 4718, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.), poly ( Examples of esters) include, for example, poly (urethanes) such as FINETEX ES650, 611, 675, 850 (above made by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (more made by Eastman Chemical). Examples of rubbers such as HYDRAN AP10, 20, 30, and 40 (manufactured by Dainippon Ink Chemical Co., Ltd.) include LACSTAR 7310K, 3307B, 4700H, and 7132C (manufactured by Dainippon Ink Chemical Co., Ltd.), Nipol Lx416, 410, 438C, 2507 (all manufactured by Nippon Zeon Co., Ltd.), etc. Examples of poly (vinyl chloride) s include G351 and G576 (manufactured by Nippon Zeon Co., Ltd.), and examples of poly (vinylidene chloride) include L502 and L513 (manufactured by Asahi Kasei Kogyo Co., Ltd.) Examples of poly (olefin) s include Chemipearl S120, SA100 (manufactured by Mitsui Petrochemical Co., Ltd.).
These polymer latexes may be used alone or in combination of two or more as required.

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

  Examples of latexes of styrene-butadiene copolymer that are preferably used in the present invention include the aforementioned P-3 to P-8, 14, and 15, commercially available products LACSTAR-3307B and 7132C, Nipol Lx416, and the like.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose may be added to the organic silver salt-containing layer of the light-sensitive material of the present invention.

  The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder of the organic silver salt-containing layer.

  The organic silver salt-containing layer (that is, the image forming layer) of 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 preferably such that the mass ratio of all binders / organic silver salt is 1/10 to 10/1, more preferably 1/5 to 4/1.

  In addition, such an organic silver salt-containing layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide which is a photosensitive silver salt. The mass ratio of silver is preferably 400-5, more preferably 200-10.

The total amount of binder in the image forming layer of the present invention is ^{0.2g / m 2 ~30g / m 2} , more preferably from 1g / m ² ~15g / m ² is preferred. The image forming layer of the present invention may contain a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like.

  In the present invention, the solvent of the organic silver salt-containing layer coating solution of the light-sensitive material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent is more preferably 50% by mass or more, and still more preferably 70% by mass or more.

  Specific examples of the preferred solvent composition include water 100, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl. Alcohol / ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical values are mass%).

(Anti-fogging agent)
1) Organic polyhalogen compound The present invention preferably contains a compound represented by the following general formula (H) as an antifoggant.

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

In the general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 or 1, Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron withdrawing group.

  Q preferably represents a phenyl group substituted with an electron-withdrawing group in which Hammett's substituent constant σp takes a positive value. For Hammett's substituent constants, see Journal of Medicinal Chemistry, 1973, Vol. 16, no. 11, p. 1207-1216 etc. can be referred to.

Examples of such an electron withdrawing group include a halogen atom (fluorine atom (σp value: 0.06), chlorine atom (σp value: 0.23), bromine atom (σp value: 0.23), iodine atom. (Σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp value: 0.54)), Cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic aryl, or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0.72)), aliphatic aryl Or a heterocyclic acyl group (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), alkynyl group (for example, C≡CH (σp value: 0.23)), aliphatic Aryl or heterocyclic oxycarbo Group (for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), Examples thereof include a sulfoxide group, a heterocyclic group, and a phosphoryl group.
The σp value is preferably in the range of 0.2 to 2.0, more preferably in the range of 0.4 to 1.0.

  Preferred as the electron withdrawing group are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, an alkylphosphoryl group, a carboxyl group, an alkyl or arylcarbonyl group, and an arylsulfonyl group, and particularly preferably a carbamoyl group and an alkoxycarbonyl group. , An alkylsulfonyl group and an alkylphosphoryl group, and a carbamoyl group is most preferred.

X is preferably an electron-withdrawing group, more preferably a halogen atom, aliphatic / aryl or heterocyclic sulfonyl group, aliphatic / aryl or heterocyclic acyl group, aliphatic / aryl or heterocyclic oxycarbonyl group, A carbamoyl group and a sulfamoyl group, particularly preferably a halogen atom.
Among the halogen atoms, a chlorine atom, a bromine atom and an iodine atom are preferable, a chlorine atom and a bromine atom are more preferable, and a bromine atom is particularly preferable.

Y preferably represents —C (═O) —, —SO— or —SO ₂ —, more preferably —C (═O) — or —SO ₂ —, and particularly preferably —SO ₂ —. . n represents 0 or 1, and is preferably 1.

  Although the specific example of the compound of general formula (H) of this invention is shown below, this invention is not limited to these.

The compound represented by the general formula (H) of the present invention is preferably used in the range of 10 ^{−4 to} 0.8 mol, more preferably 10 ⁻³ per mol of the non-photosensitive silver salt of the image forming layer. It is preferable to use in the range of ˜0.1 mol, more preferably in the range of 5 × 10 ^{−3 to} 0.05 mol.
In particular, when a silver halide having a high silver iodide content according to the present invention is used, the addition amount of the compound of the general formula (H) is important in order to obtain a sufficient antifogging effect. Most preferably, it is used in the range of 10 ^{−3 to} 0.03 mol.

  In the present invention, examples of the method for incorporating the compound represented by the general formula (H) into the photosensitive material include the methods described in the method for containing a reducing agent.

  The melting point of the compound represented by the general formula (H) is preferably 200 ° C. or lower, more preferably 170 ° C. or lower.

  Other organic polyhalides used in the present invention include those disclosed in the patents described in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021. In particular, an organic halogen compound represented by the formula (P) in JP-A No. 2000-284399, an organic polyhalogen compound represented by the general formula (II) in JP-A No. 10-339934, and the compounds described in JP-A No. 2001-33911 Organic polyhalogen compounds are preferred.

2) Other antifoggants Other antifoggants include mercury (II) salts described in paragraph No. 0113 of JP-A No. 11-65021, benzoic acids described in paragraph No. 0114 of the same, salicylic acid derivatives of JP-A No. 2000-206642, A formalin scavenger compound represented by the formula (S) in JP-A-2000-221634, a triazine compound according to claim 9 in JP-A-11-352624, and a compound represented by the general formula (III) in JP-A-6-11791 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene and the like.

  Antifoggant, stabilizer and stabilizer precursor that can be used in the present invention described in paragraph No. 0070 of JP-A-10-62899, page 20, line 57 to page 21, line 7 of European Patent No. 0803764A1 Patented compounds and compounds described in JP-A Nos. 9-281737 and 9-329864 can be mentioned.

  The photothermographic material in the invention may contain an azolium salt for the purpose of preventing fogging. Examples of the azolium salt include compounds represented by general formula (XI) described in JP-A-59-193447, compounds described in JP-B-55-12581, and general formula (II) described in JP-A-60-153039. And the compounds represented. The azolium salt may be added to any part of the photosensitive material, but the addition layer is preferably added to the layer having the photosensitive layer, and more preferably to the organic silver salt-containing layer.

  The azolium salt may be added at any step in the coating solution preparation. When added to the organic silver salt-containing layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. To immediately before coating. The azolium salt may be added by any method such as powder, solution, or fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent.

In the present invention, the azolium salt may be added in any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, and more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

(Other additives)
1) Mercapto, disulfide, and thiones In the present invention, mercapto compounds and disulfide compounds are used to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. And thione compounds, paragraphs 0067 to 0069 of JP-A-10-62899, compounds represented by formula (I) of JP-A-10-186572, and specific examples thereof include paragraph numbers 0033 to 0052. , European Patent Publication No. 0803764A1, page 20, lines 36 to 56, JP-A-2001-1003008 and the like. Of these, mercapto-substituted heteroaromatic compounds are preferred.

2) Toning agent In the photothermographic material of the invention, it is preferable to add a toning agent. For the toning agent, paragraphs 0054 to 0055 of JP-A No. 10-62899, p. Lines 21, 23 to 48, JP-A No. 2000-356317 and Japanese Patent Application No. 2000-187298, in particular, phthalazinones (phthalazinone, phthalazinone derivatives or metal salts; for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, A combination of diammonium phthalate, sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride); phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6 -T-butylphthalazine, 6-chloro (Talazine, 5.7-dimethoxyphthalazine, and 2,3-dihydrophthalazine) are preferable. In particular, in the combination with silver halide having a high silver iodide content, the combination of phthalazine and phthalic acid is preferable.

  The amount of phthalazine added is preferably 0.01 to 0.3 mol, more preferably 0.02 to 0.2 mol, particularly preferably 0.02 to 0.1 mol, per mol of the organic silver salt. It is. This addition amount is an important factor for promoting development, which is a problem in the silver halide emulsion having a high silver iodide content of the present invention. By selecting an appropriate addition amount, both sufficient developability and low fog are achieved. Is possible.

3) Plasticizers and lubricants Plasticizers and lubricants that can be used in the photosensitive layer of the invention are described in paragraph No. 0117 of JP-A No. 11-65021. The slip agent is described in JP-A No. 11-84573, paragraph numbers 0061 to 0064 and Japanese Patent Application No. 11-106881, paragraph numbers 0049 to 0062.

4) Dye and Pigment The photosensitive layer of the present invention has various dyes and pigments (for example, CI Pigment Blue 60, CI Pigment, etc.) from the viewpoints of improving the color tone, preventing interference fringes during laser exposure, and preventing irradiation. Blue 64, CI Pigment Blue 15: 6) can be used. These are described in detail in WO98 / 36322, JP-A-10-268465, JP-A-11-338098 and the like.

(Nucleating agent)
The nucleating agent according to the present invention will be described. The nucleating agent according to the present invention refers to a compound that can reduce the amount of silver necessary to obtain a certain silver image density. Various action mechanisms of the function of decreasing can be considered, but a compound having a function of improving the covering power of developed silver is preferable. Here, the covering power of developed silver refers to the optical density per unit amount of silver.

  As the nucleating agent, a hydrazine derivative compound represented by the following general formula (H), a vinyl compound represented by the following general formula (G), a quaternary onium compound represented by the following general formula (P), the formula (A) Preferred examples include cyclic olefin compounds represented by formula (B) and general formula (C).

General formula (H)

General formula (G)

General formula (P)

Formula (A)

General formula (B)

General formula (C)

In the general formula [H], A ₀ represents an aliphatic group, aromatic group, heterocyclic group or -G ₀ -D ₀ group which may have a substituent, and B ₀ represents a blocking group. , A ₁ and A ₂ both represent a hydrogen atom, or one represents a hydrogen atom and the other represents an acyl group, a sulfonyl group or an oxalyl group. Here, G ₀ is —CO— group, —COCO— group, —CS— group, —C (═NG ₁ D ₁ ) — group, —SO— group, —SO ₂ — group or —P (O) ( G ₁ D ₁ ) — group, G ₁ represents a simple bond, —O— group, —S— group or —N (D ₁ ) — group, D ₁ represents an aliphatic group, aromatic group, complex When a ring group or a hydrogen atom is represented and a plurality of D ₁ are present in the molecule, they may be the same or different. D ₀ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group. Preferred D ₀ includes a hydrogen atom, an alkyl group, an alkoxy group, an amino group and the like.

In the general formula (H), the aliphatic group represented by A ₀ is preferably one having 1 to 30 carbon atoms, particularly preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. Examples thereof include a methyl group, an ethyl group, a t-butyl group, an octyl group, a cyclohexyl group, and a benzyl group. These are further suitable substituents (for example, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a sulfoxy group). Group, sulfonamido group, sulfamoyl group, acylamino group, ureido group, etc.).

In the general formula (H), the aromatic group represented by A ₀ is preferably a monocyclic or condensed aryl group, such as a benzene ring or a naphthalene ring, and the heterocyclic group represented by A ₀ is A heterocyclic ring containing at least one heteroatom selected from nitrogen, sulfur and oxygen atoms in a single ring or a condensed ring is preferred, such as a pyrrolidine ring, an imidazole ring, a tetrahydrofuran ring, a morpholine ring, a pyridine ring, a pyrimidine ring, a quinoline ring, Examples include a thiazole ring, a benzothiazole ring, a thiophene ring, and a furan ring. Aromatic groups A _0, heterocyclic group or -G ₀ -D ₀ group may have a substituent. Particularly preferred as A ₀ are an aryl group and a —G ₀ -D ₀ group.

In the general formula (H), A ₀ preferably contains at least one anti-diffusion group or silver halide adsorption group. As the anti-diffusion group, a ballast group commonly used in an immobile photographic additive such as a coupler is preferable. As the ballast group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, phenyl, which are photographically inactive, are preferable. Group, phenoxy group, alkylphenoxy group and the like, and the total number of carbon atoms in the substituent portion is preferably 8 or more.

  In the general formula (H), examples of the silver halide adsorption promoting group include thiourea, thiourethane group, mercapto group, thioether group, thione group, heterocyclic group, thioamide heterocyclic group, mercapto heterocyclic group, and JP-A-64. And the adsorbing group described in -90439.

In the general formula (H), B ₀ represents a blocking group, preferably a -G ₀ -D ₀ group, and G ₀ is a -CO- group, a -COCO- group, a -CS- group, -C (= NG ₁ D ₁ ) — group, —SO— group, —SO ₂ — group or —P (O) (G ₁ D ₁ ) — group. Preferred examples of G ₀ include —CO— group and —COCO— group, G ₁ represents a simple bond, —O— group, —S— group or —N (D ₁ ) — group, and D ₁ represents fatty acid. Represents a group, an aromatic group, a heterocyclic group or a hydrogen atom, and when a plurality of D ₁ are present in the molecule, they may be the same or different. D ₀ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group, and preferred D ₀ is a hydrogen atom, an alkyl group, an alkoxy group, An amino group etc. are mentioned. A ₁ and A ₂ are both hydrogen atoms, or one is a hydrogen atom and the other is an acyl group (acetyl group, trifluoroacetyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, toluenesulfonyl group, etc.), or oxalyl group (Etoxalyl group, etc.).

  Specific examples of the compound represented by the general formula (H) include compounds of Chemical Formula No. 12 to Chemical Formula No. 18 of H-1 to H-35, and Chemical Formula No. 20 to Chemical Formula No. 26 of H.2002-131864. Although the compound of 1-1 to H-4-5 is raised, it is not limited to these.

  These compounds represented by the general formulas (H-1) to (H-4) of the present invention can be easily synthesized by known methods. For example, it can be synthesized with reference to US Pat. Nos. 5,464,738 and 5,496,695.

  Other hydrazine derivatives that can be preferably used include compounds H-1 to H-29 described in U.S. Pat. No. 5,545,505 columns 11 to 20, and U.S. Pat. No. 5,464,738 columns 9 to 11. Compounds 1 to 12 described. These hydrazine derivatives can be synthesized by a known method.

  General formula (G) is demonstrated. In the general formula (G), X and R are shown in a cis form, but a form in which X and R are trans is also included in the general formula (G). The same applies to the structure display of a specific compound.

  In the general formula (G), X represents an electron withdrawing group, and W represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a halogen atom, an acyl group, a thioacyl group, an oxalyl group. , Oxyoxalyl, thiooxalyl, oxamoyl, oxycarbonyl, thiocarbonyl, carbamoyl, thiocarbamoyl, sulfonyl, sulfinyl, oxysulfinyl, thiosulfinyl, sulfamoyl, oxysulfinyl, thiosulfinyl Represents a group, sulfinamoyl group, phosphoryl group, nitro group, imino group, N-carbonylimino group, N-sulfonylimino group, dicyanoethylene group, ammonium group, sulfonium group, phosphonium group, pyrylium group, immonium group.

  R is a halogen atom, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, alkenyloxy group, acyloxy group, alkoxycarbonyloxy group, aminocarbonyloxy group, mercapto group, alkylthio group, arylthio group, heterocyclic thio Group, alkenylthio group, acylthio group, alkoxycarbonylthio group, aminocarbonylthio group, organic group or inorganic salt of hydroxyl group or mercapto group (for example, sodium salt, potassium salt, silver salt), amino group, alkylamino group , Cyclic amino group (for example, pyrrolidino group), acylamino group, oxycarbonylamino group, heterocyclic group (5- to 6-membered nitrogen-containing heterocycle such as benztriazolyl group, imidazolyl group, triazolyl group, tetrazolyl group, etc.) Ureido group, sulfo An amide group. X and W, X and R may be bonded to each other to form a cyclic structure. Examples of the ring formed by X and W include pyrazolone, pyrazolidinone, cyclopentanedione, β-ketolactone, β-ketolactam and the like.

  The general formula (G) will be further described. The electron withdrawing group represented by X is a substituent whose substituent constant σp can take a positive value. Specifically, a substituted alkyl group (such as halogen-substituted alkyl), a substituted alkenyl group (such as cyanovinyl), a substituted / unsubstituted alkynyl group (such as trifluoromethylacetylenyl, cyanoacetylenyl), a substituted aryl group (such as cyano) Phenyl, etc.), substituted / unsubstituted heterocyclic groups (pyridyl, triazinyl, benzoxazolyl, etc.), halogen atoms, cyano groups, acyl groups (acetyl, trifluoroacetyl, formyl, etc.), thioacetyl groups (thioacetyl, thioformyl, etc.) ), Oxalyl group (such as methyloxalyl), oxyoxalyl group (such as etoxalyl), thiooxalyl group (such as ethylthiooxalyl), oxamoyl group (such as methyloxamoyl), oxycarbonyl group (such as ethoxycarbonyl), carboxyl group, thiol Carbonyl group (ethylthiocarboni ), Carbamoyl group, thiocarbamoyl group, sulfonyl group, sulfinyl group, oxysulfonyl group (such as ethoxysulfonyl), thiosulfonyl group (such as ethylthiosulfonyl), sulfamoyl group, oxysulfinyl group (such as methoxysulfinyl), thiosulfinyl group (Such as methylthiosulfinyl), sulfinamoyl group, phosphoryl group, nitro group, imino group, N-carbonylimino group (N-acetylimino etc.), N-sulfonylimino group (N-methanesulfonylimino etc.), dicyanoethylene group, ammonium Group, sulfonium group, phosphonium group, pyrylium group, immonium group, and the like include a heterocyclic group in which an ammonium group, sulfonium group, phosphonium group, immonium group and the like form a ring. A substituent having a σp value of 0.30 or more is particularly preferable.

  Examples of the alkyl group represented by W include methyl, ethyl, trifluoromethyl, etc., examples of the alkenyl group include vinyl, halogen-substituted vinyl, cyanovinyl, etc., examples of the alkynyl group include acetylenyl, cyanoacetylenyl, and the like as the aryl group. Nitrophenyl, cyanophenyl, pentafluorophenyl and the like, and examples of the heterocyclic group include pyridyl, pyrimidyl, triazinyl, succinimide, tetrazolyl, triazolyl, imidazolyl and benzoxazolyl. W is preferably an electron-attracting group having a positive σp value, and more preferably 0.30 or more.

  Among the substituents of R, a hydroxyl group, a mercapto group, an alkoxy group, an alkylthio group, a halogen atom, an organic or inorganic salt of a hydroxyl group or a mercapto group, and a heterocyclic group are preferable, and a hydroxyl group, more preferably An organic or inorganic salt of an alkoxy group, a hydroxyl group or a mercapto group, or a heterocyclic group is exemplified, and an organic or inorganic salt of a hydroxyl group, a hydroxyl group or a mercapto group is particularly preferred.

  Of the substituents X and W, those having a thioether bond in the substituent are preferred.

  Specific examples of the compound represented by the general formula (G) include chemical formula number 27 to chemical formula number 50-1 to 92-7 in JP-A No. 2002-131864, but are not limited thereto. Absent.

In the general formula (P), Q represents a nitrogen atom or a phosphorus atom, R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom or a substituent, and X ⁻ represents an anion. R _{1 to} R ₄ may be connected to each other to form a ring.

Examples of the substituent represented by R _{1 to} R ₄ include an alkyl group (methyl group, ethyl group, propyl group, butyl group, hexyl group, cyclohexyl group, etc.), alkenyl group (allyl group, butenyl group, etc.), alkynyl group. (Propargyl group, butynyl group, etc.), aryl group (phenyl group, naphthyl group, etc.), heterocyclic group (piperidinyl group, piperazinyl group, morpholinyl group, pyridyl group, furyl group, thienyl group, tetrahydrofuryl group, tetrahydrothienyl group, Sulfolanyl group etc.), amino group etc. are mentioned.

Examples of the ring that R _{1 to} R ₄ can form together are a piperidine ring, a morpholine ring, a piperazine ring, a quinuclidine ring, a pyridine ring, a pyrrole ring, an imidazole ring, a triazole ring, and a tetrazole ring.

The group represented by R _{1 to} R ₄ may have a substituent such as a hydroxyl group, an alkoxy group, an aryloxy group, a carboxyl group, a sulfo group, an alkyl group, and an aryl group. R ₁ , R ₂ , R ₃ and R ₄ are preferably a hydrogen atom and an alkyl group.

Examples of the anion represented by X ⁻ include inorganic and organic anions such as halogen ions, sulfate ions, nitrate ions, acetate ions, and p-toluenesulfonate ions.

  As the structure of the general formula (P), the structures described in paragraph numbers 0153 to 0163 of JP-A No. 2002-131864 are more preferable.

  Specific examples of the general formula (P) include, but are not limited to, P-1 to P-52 and T-1 to T-18 of Chemical Formula No. 53 to Chemical Formula No. 62 of JP-A No. 2002-131864. Is not to be done.

  The quaternary onium compound can be synthesized by referring to known methods. For example, the tetrazolium compound can be synthesized by referring to Chemical Reviews, vol. 55, p. The method described in 335-483 can be referred to.

Next, the compounds represented by formulas (A) and (B) will be described in detail. In the formula (A), Z ₁ represents a nonmetallic atomic group capable of forming a 5-membered to 7-membered ring structure with —Y ₁ —C (═CH—X ₁ ) —C (═O) —. Z ₁ is preferably an atomic group selected from a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, and a hydrogen atom, and several atoms selected from these are connected to each other by a single bond or a double bond. _{Te, -Y 1 -C (= CH-} X 1) -C (= O) - form a 5- to 7-membered ring structure with. Z ₁ may have a substituent, and Z ₁ itself may be part of an aromatic or non-aromatic carbocyclic ring or an aromatic or non-aromatic heterocyclic ring, in this case , Z ₁ together with —Y ₁ —C (═CH—X ₁ ) —C (═O) — forms a condensed ring structure.

In the formula (B), Z ₂ represents a nonmetallic atomic group capable of forming a 5-membered to 7-membered ring structure together with —Y ₂ —C (═CH—X ₂ ) —C (Y ₃ ) ═N—. Z ₂ is preferably an atomic group selected from a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, and a hydrogen atom, and several atoms selected from these are connected to each other by a single bond or a double bond. _{Te, -Y 2 -C (= CH-} X 2) -C (Y 3) = to form a 5- to 7-membered ring structure with N-. Z ₂ may have a substituent, and Z ₂ itself may be part of an aromatic or non-aromatic carbocycle or an aromatic or non-aromatic heterocycle, in which case , Z ₂ together with —Y ₂ —C (═CH—X ₂ ) —C (Y ₃ ) ═N— forms a condensed ring structure.

When Z ₁ and Z ₂ have a substituent, examples of the substituent are selected from those listed below. That is, typical substituents include, for example, halogen atoms (fluorine atoms, chloro atoms, bromine atoms, or iodine atoms), alkyl groups (including aralkyl groups, cycloalkyl groups, active methine groups, etc.), alkenyl groups, alkynyls. Group, aryl group, heterocyclic group, quaternized heterocyclic group containing a nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxy group or salt thereof, sulfonylcarbamoyl A group, an acylcarbamoyl group, a sulfamoylcarbamoyl group, a carbazoyl group, an oxalyl group, an oxamoyl group, a cyano group, a thiocarbamoyl group, a hydroxy group, an alkoxy group (including a group repeatedly containing an ethyleneoxy group or a propyleneoxy group unit), Aryloxy group, heterocyclic o Si group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, N-substituted nitrogen-containing heterocyclic group, acylamino Group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, quaternary ammonio group, oxamoylamino Group, (alkyl or aryl) sulfonylureido group, acylureido group, acylsulfamoylamino group, nitro group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl or aryl) sulfonyl group, ( (Alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, acylsulfamoyl group, sulfonylsulfamoyl group or a salt thereof, a group containing a phosphate amide or phosphate ester structure, a silyl group, a stannyl group, etc. Can be mentioned. These substituents may be further substituted with these substituents.

Next, Y ₃ will be described. In formula (B), Y ₃ represents a hydrogen atom or a substituent. When Y ₃ represents a substituent, specific examples of the substituent include the following groups. That is, alkyl group, aryl group, heterocyclic group, cyano group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide Group, ureido group, thioureido group, imide group, alkoxy group, aryloxy group, (alkyl, aryl, or heterocyclic) thio group and the like. These substituents may be substituted with an arbitrary substituent, and specific examples of the substituent that Z ₁ or Z ₂ may have are given.

In the formula (A) and the formula (B), X ₁ and X ₂ are each a hydroxy group (or a salt thereof), an alkoxy group (for example, methoxy group, ethoxy group, propoxy group, isopropoxy group, octyloxy group, dodecyloxy group) Group, cetyloxy group, t-butoxy group, etc.), aryloxy group (for example, phenoxy group, pt-pentylphenoxy group, pt-octylphenoxy group, etc.), heterocyclic oxy group (for example, benzotriazolyl-5) -Oxy group, pyridinyl-3-oxy group, etc.), mercapto group (or salt thereof), alkylthio group (for example, methylthio group, ethylthio group, butylthio group, dodecylthio group, etc.), arylthio group (for example, phenylthio group, p-dodecylphenyl) Thio group etc.), heterocyclic thio group (for example, 1-phenyltetrazoyl-5-thio group) 2-methyl-1-phenyltriazolyl-5-thio group, mercaptothiadiazolylthio group, etc.), amino group, alkylamino group (for example, methylamino group, propylamino group, octylamino group, dimethylamino group, etc.) ), Arylamino groups (for example, anilino group, naphthylamino group, o-methoxyanilino group, etc.), heterocyclic amino groups (for example, pyridylamino group, benzotriazol-5-ylamino group, etc.), acylamino groups (for example, acetamide group, octa A noylamino group, a benzoylamino group, etc.), a sulfonamide group (for example, a methanesulfonamide group, a benzenesulfonamide group, a dodecylsulfonamide group, etc.), or a heterocyclic group.

  Here, the heterocyclic group is an aromatic or non-aromatic, saturated or unsaturated, monocyclic or condensed, substituted or unsubstituted heterocyclic group such as an N-methylhydantoyl group, N- Phenylhydantoyl group, succinimide group, phthalimide group, N, N'-dimethylurazolyl group, imidazolyl group, benzotriazolyl group, indazolyl group, morpholino group, 4,4-dimethyl-2,5-dioxo-oxazolyl Groups and the like.

Further, the salt here is an alkali metal (sodium, potassium, lithium) or alkaline earth metal (magnesium, calcium) salt, silver salt, or quaternary ammonium salt (tetraethylammonium salt, dimethylcetylbenzylammonium salt, etc.), Represents a quaternary phosphonium salt and the like. In the formula (A) and the formula (B), Y ₁ and Y ₂ represent —C (═O) — or —SO ₂ —.

  Preferable ranges of the compounds represented by formula (A) and formula (B) are described in paragraph Nos. 0027 to 0043 of JP-A No. 11-231459. Specific examples of the compounds of formula (A) and formula (B) include, but are not limited to, compounds 1 to 110 of Table 1 to Table 8 of JP-A No. 11-231459.

Next, the compound represented by formula (C) of the present invention will be described in detail. In the general formula (C), X ₁ represents an oxygen atom, a sulfur atom, or a nitrogen atom. When X ₁ is a nitrogen atom, the bond between X ₁ and Z ₁ may be a single bond or a double bond. In the case of a single bond, the nitrogen atom has a hydrogen atom or an arbitrary substituent. Also good. Examples of the substituent include alkyl groups (including aralkyl groups, cycloalkyl groups, and active methine groups), alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, carbamoyl groups. Group, (alkyl, aryl or heterocyclic) sulfonyl group and the like.
Y ₁ is -C (= O) -, - C (= S) -, - SO -, - SO 2 -, - C (= NR 3) -, - it is (R ₄₎ expressed by C = N- Represents a group. Z ₁ represents a nonmetallic atomic group capable of forming 5 to 7 members including X ₁ and Y ₁ . The atomic group forming the ring is an atomic group composed of atoms other than 2 to 4 metal atoms, and these atoms may be bonded by a single bond or a double bond. It may have a substituent (for example, an alkyl group, aryl group, heterocyclic group, alkoxy group, alkylthio group, acyl group, amino group, alkenyl group). When Z ₁ forms 5 to 7 members including X ₁ and Y ₁ , the ring is a saturated or unsaturated hetero ring, which may be monocyclic or have a condensed ring. In this case, the condensed ring is formed when Y ₁ is a group represented by C (═NR ₃ ) or (R ₄ ) C═N, and R ₃ or R ₄ is bonded to a substituent of Z _1. It may be done.

In the general formula (C), R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom or a substituent. However, R ₁ and R ₂ are not bonded to each other to form a cyclic structure.

When R ₁ and R ₂ represent a monovalent substituent, examples of the monovalent substituent include the following groups.

  For example, halogen atom (fluorine atom, chloro atom, bromine atom or iodine atom), alkyl group (including aralkyl group, cycloalkyl group, active methine group, etc.), alkenyl group, alkynyl group, aryl group, heterocycle (heterocycle) ) Group, a quaternized heterocyclic group containing a nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxy group or a salt thereof, sulfonylcarbamoyl group, acylcarbamoyl group, A sulfamoylcarbamoyl group, a carbazoyl group, an oxalyl group, an oxamoyl group, a cyano group, a thiocarbamoyl group, a hydroxyl group (hydroxy group) or a salt thereof, an alkoxy group (including a group repeatedly containing an ethyleneoxy group or a propyleneoxy group unit), Aryloxy group, hetero Oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, N-substituted nitrogen-containing heterocyclic group, acylamino Group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, quaternary ammonio group, oxamoylamino Group, (alkyl or aryl) sulfonylureido group, acylureido group, acylsulfamoylamino group, nitro group, mercapto group or salt thereof, (alkyl, aryl, or heterocyclic) thio group, (alkyl or aryl) A group containing a sulfonyl group, an (alkyl or aryl) sulfinyl group, a sulfo group or a salt thereof, a sulfamoyl group, an acylsulfamoyl group, a sulfonylsulfamoyl group or a salt thereof, a phosphoryl group, a phosphate amide or a phosphate ester structure, A silyl group, a stannyl group, etc. are mentioned. These substituents may be further substituted with these monovalent substituents.

Next, when R ₃ and R ₄ represent a substituent, examples of the substituent include the same substituents that R ₁ and R ₂ may have except for a halogen atom. R ₃ and R ₄ may be further linked to Z ₁ to form a condensed ring.

Next, a preferable thing is demonstrated among the compounds represented by general formula (C). In the general formula (C), Z ₁ preferably forms a 5- to 7-membered ring together with X ₁ and Y ₁ and is an atomic group consisting of atoms selected from 2 to 4 carbon atoms, nitrogen atoms, sulfur atoms and oxygen atoms. And the heterocycle formed by Z ₁ together with X ₁ and Y ₁ is preferably a heterocycle having a total carbon number of 3 to 40, more preferably 3 to 25, most preferably 3 to 20, and Z ₁ is Preferably it contains at least one carbon atom.

In formula (C), Y ₁ is preferably —C (═O) —, —C (═S) —, —SO ₂ —, — (R ₄ ) C═N—, particularly preferably —C ( = O) -, - C ( = S) -, - SO 2 - a, and most preferably -C (= O) - it is.

When R _1, R ₂ represents a monovalent substituent in formula (C), R _1, examples of preferred monovalent substituent represented by R _2, a total carbon number of 0-25 following the Group, that is, alkyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, heterocyclic oxy group, alkylthio group, arylthio group, heterocyclic thio group, amino group, alkylamino group, arylamino group, heterocyclic amino group Group, ureido group, imide group, acylamino group, hydroxy group or salt thereof, mercapto group or salt thereof, or electron-withdrawing substituent. Here, the electron-withdrawing substituent is a substituent whose Hammett's substituent constant σp can take a positive value, specifically, a cyano group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group. , Sulfonamido group, imino group, nitro group, halogen atom, acyl group, formyl group, phosphoryl group, carboxy group (or salt thereof), sulfo group (or salt thereof), saturated or unsaturated heterocyclic group, alkenyl group , An alkynyl group, an acyloxy group, an acylthio group, a sulfonyloxy group, or an aryl group substituted with these electron-withdrawing groups. These groups may have an arbitrary substituent.

In the general formula (C), when R ₁ and R ₂ represent a monovalent substituent, more preferably an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, amino Group, alkylamino group, arylamino group, heterocyclic amino group, ureido group, imide group, acylamino group, sulfonamide group, heterocyclic group, hydroxy group or salt thereof, mercapto group or salt thereof, and the like. In the general formula (C), R ₁ and R ₂ are particularly preferably a hydrogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a heterocyclic group, a hydroxy group or a salt thereof, a mercapto group or a salt thereof, and the like. . In general formula (C), most preferably one of R ₁ and R ₂ is a hydrogen atom and the other is an alkoxy group, aryloxy group, alkylthio group, arylthio group, heterocyclic group, hydroxy group or salt thereof, mercapto group or Its salt.

When R ₃ represents a substituent in the general formula (C), preferably an alkyl group having 1 to 25 carbon atoms in total (including an aralkyl group, a cycloalkyl group, an active methine group, etc.), an alkenyl group, an aryl group, Heterocyclic group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) Examples thereof include a sulfinyl group, a sulfosulfamoyl group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, and an amino group. Particularly preferred are an alkyl group and an aryl group.

In the general formula (C), when R ₄ represents a substituent, it is preferably an alkyl group having 1 to 25 carbon atoms in total (including an aralkyl group, a cycloalkyl group, an active methine group, etc.), an aryl group, and a heterocyclic group. A heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, A sulfosulfamoyl group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group and the like are used. Particularly preferred are an alkyl group, aryl group, alkoxy group, aryloxy group, heterocyclic oxy group, alkylthio group, arylthio group, heterocyclic thio group and the like. When Y ₁ represents C (R ₄ ) ═N, it is the carbon atom in Y _{1 that} is bonded to the carbon atom substituted by X ₁ and Y ₁ .

  Specific compounds of the general formula (C) are represented by A-1 to A-230 of Chemical Formula No. 6 to Chemical Formula No. 18 described in JP-A No. 11-133546, but are not limited to these compounds.

The addition amount of the nucleating agent is in the range of 10 ⁻⁵ to 1 mol, preferably 10 ^{−4 to} 5 × 10 ⁻¹ mol, relative to 1 mol of the organic silver salt.
The nucleating agent may be added to the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.
Well-known emulsification and dispersion methods include oils such as dibutyl phthalate, tricresyl phosphate, dioctyl sebacate or tri (2-ethylhexyl) phosphate, and dissolution using an auxiliary solvent such as ethyl acetate or cyclohexanone, and dodecylbenzene. Examples include a method of mechanically preparing an emulsified dispersion by adding a surfactant such as sodium sulfonate, oleoyl-N-methyl taurate, sodium di (2-ethylhexyl) sulfosuccinate. At this time, it is also preferable to add a polymer such as α-methylstyrene oligomer or poly (t-butylacrylamide) for the purpose of adjusting the viscosity and refractive index of the oil droplets.

In addition, as a solid fine particle dispersion method, a nucleating agent powder is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill or ultrasonic waves to produce a solid dispersion. The method of doing is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or 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. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the content of Zr in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem.
The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).
Particularly preferred is a solid particle dispersion method of a nucleating agent, which is preferably added as fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. . In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

Among the above nucleating agents, it is preferable to use compounds represented by the general formulas (H) and (P), particularly preferably the general formula, in a photosensitive material processed by rapid development with a development time of 20 seconds or less. The compound represented by (H) is preferred.
In light-sensitive materials that require low fog, it is preferable to use compounds represented by the general formulas (G), (A), (B), and (C), and particularly preferably, the general formulas (A) and (B) are used. It is a compound represented. Further, it is preferable to use a compound represented by the general formula (C) for a light-sensitive material having little change in photographic performance with respect to environmental conditions when used under various environmental conditions (temperature, humidity).
Specific preferred compounds among the above nucleating agents are listed below, but are not limited to these compounds.

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution of the present invention is preferably from 30 ° C. to 65 ° C., more preferably from 35 ° C. to less than 60 ° C., and more preferably from 35 ° C. to 55 ° C. Moreover, it is preferable that the temperature of the image forming layer coating liquid immediately after the addition of the polymer latex is maintained at 30 ° C. or higher and 65 ° C. or lower.

(Layer structure and components)
The photothermographic material of the present invention can have a non-photosensitive layer in addition to the image forming layer. The non-photosensitive layer includes (a) a surface protective layer provided on the image forming layer (on the side farther than the support), (b) between the plurality of image forming layers and between the image forming layer and the protective layer. It can be classified into an intermediate layer provided therebetween, (c) an undercoat layer provided between the image forming layer and the support, and (d) a back layer provided on the opposite side of the image forming layer.

  In addition, although a layer acting as an optical filter can be provided, it is provided as the layer (a) or (b). The antihalation layer is provided on the photosensitive material as the layer (c) or (d).

1) Surface protective layer 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. The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and JP-A No. 2001-348546.

  As the binder for the surface protective layer of the present invention, gelatin is preferable, but it is also preferable to use polyvinyl alcohol (PVA) or a combination thereof. As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), and the like can be used.

  Examples of PVA include those described in paragraph Nos. 0009 to 0020 of JP-A No. 2000-171936. Completely saponified PVA-105, partially saponified PVA-205, PVA-335, and modified polyvinyl alcohol MP- Preferred is 203 (trade name, manufactured by Kuraray Co., Ltd.).

Preferably 0.3g / m ² ~4.0g / m ² as a polyvinyl alcohol coating amount (per support 1 m ²⁾ of the protective layer (per one ^{layer), 0.3g / m 2 ~2.0g /} m 2 Is more preferable.

All (including water-soluble polymer and latex polymer) binder preferably 0.3g / m ² ~5.0g / m ² as a coating amount (per support 1 m ²⁾ of the surface protective layer (per one layer), 0. 3g / m ² ~2.0g / m ² is more preferable.

2) Antihalation layer In the photothermographic material of the invention, the antihalation layer can be provided on the side farther from the exposure light source than the photosensitive layer. As for the antihalation layer, paragraphs 0123 to 0124 of JP-A-11-65021, JP-A-11-223898, 9-230531, 10-36695, 10-104779, 11-231457, 11 -352625, 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 antihalation is performed using a dye having absorption in the visible range, it is preferable that substantially no dye color remains after image formation, and a means for decoloring by the heat of heat development is used. In particular, it is preferable to add a thermally decolorable 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 and the like.

The amount of decoloring dye added is determined by the use of the dye. In general, an optical density (absorbance) when measured at a target wavelength is used in an amount exceeding 0.1. The optical density is preferably 0.2-2. The amount of the dye for obtaining such an optical density is generally 0.001g / m ² ~1g / m ² approximately.

  When the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.

  In thermal decoloration using such decoloring dyes and base precursors, substances that lower the melting point by 3 ° C. or more when mixed with a base precursor as described in JP-A No. 11-352626 (for example, diphenylsulfone, 4-chlorophenyl, etc.) (Phenyl) sulfone) is preferably used in view of thermal decoloring properties.

3) Back Layer Back layers that can be applied to the present invention are described in paragraph numbers 0128 to 0130 of JP-A No. 11-65021.

In the present invention, a colorant having an absorption maximum at 300 nm to 450 nm can be added for the purpose of improving the silver tone and the temporal change of the image. Such colorants are disclosed in JP-A-62-210458, JP-A-63-104046, JP-A-63-103235, JP-A-63-208846, JP-A-63-306436, JP-A-63-141435, and JP-A-01-61745. And JP-A No. 2001-100363. Such a colorant is usually added in the range of 0.1 mg / m ^{2 to 1} g / m ² , and the back layer provided on the opposite side of the photosensitive layer is preferable as the layer to be added.

4) Matting agent In the present invention, it is preferable to add a matting agent to the surface protective layer and the back layer in order to improve transportability. Matting agents are described in JP-A No. 11-65021, paragraph numbers 0126 to 0127.
The matting agent is preferably 1 to 400 mg / m ² , more preferably 5 to 300 mg / m ² in terms of the coating amount per 1 m ² of the photosensitive material.

  The emulsion surface may have any matte degree as long as it does not cause a so-called stardust failure in which small white spots occur in the image area and light leakage occurs, but the Beck smoothness is preferably 30 seconds to 2000 seconds, It is preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily obtained by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.

  In the present invention, the matte degree of the back layer is preferably a Beck smoothness of 1200 seconds or less and 10 seconds or more, preferably 800 seconds or less and 20 seconds or more, and more preferably 500 seconds or less and 40 seconds or more.

  In the present invention, the matting agent is preferably contained in the outermost surface layer of the photosensitive material, the layer functioning as the outermost surface layer, or a layer close to the outer surface, and is contained in a layer acting as a so-called protective layer. It is preferable.

5) Polymer latex A polymer latex can be added to the surface protective layer or the back layer of the present invention.
For such polymer latex, “Synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing (1978))”, “Application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, Takashi "Molecular Publications (1993))" and "Synthetic Latex Chemistry (Muroichi Muroi, published by High Polymers Publication (1970))", specifically methyl methacrylate (33.5% by mass) / Ethyl acrylate (50 wt%) / Methacrylic acid (16.5 wt%) copolymer latex, Methyl methacrylate (47.5 wt%) / Butadiene (47.5 wt%) / Itaconic acid (5 wt%) copolymer Latex, latex of ethyl acrylate / methacrylic acid copolymer, methyl methacrylate (58.9% by mass) / 2-ethyl Latex of xyl acrylate (25.4 mass%) / styrene (8.6 mass%) / 2-hydroxyethyl methacrylate (5.1 mass%) / acrylic acid (2.0 mass%) copolymer, methyl methacrylate (64. 0 mass%) / styrene (9.0 mass%) / butyl acrylate (20.0 mass%) / 2-hydroxyethyl methacrylate (5.0 mass%) / acrylic acid (2.0 mass%) copolymer latex, etc. Is mentioned.

  The polymer latex is preferably used in an amount of 10% by mass to 90% by mass, particularly preferably 20% by mass to 80% by mass, based on the total binder (including the water-soluble polymer and latex polymer) of the surface protective layer or the back layer.

6) Membrane pH
The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before heat development. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2.

The film surface pH is preferably adjusted using an organic acid such as a phthalic acid derivative, a non-volatile 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 volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or heat development.
Further, it is also preferable to use ammonia and a non-volatile base such as sodium hydroxide, potassium hydroxide or lithium hydroxide in combination. A method for measuring the film surface pH is described in paragraph No. 0123 of JP-A No. 2000-284399.

7) Hardener A hardener may be used for each layer such as the photosensitive layer, protective layer, and back layer of the present invention.
Examples of hardeners include T.W. H. There are various methods described in "THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION" by James (published by Macmillan Publishing Co., Inc., published in 1977), pages 77 to 87, Chrome Alum, 2,4-dichloro-6 In addition to hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfonacetamide), N, N-propylenebis (vinylsulfonacetamide), polyvalent metal ions described on page 78 of the same document, US Pat. No. 4,281 , 060, and JP-A-6-208193, epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A-62-89048 are preferably used.

  The hardening agent is added as a solution, and the addition time of this solution into the protective layer coating solution is from 180 minutes before to immediately before application, preferably from 60 minutes to 10 seconds before application. As long as the effects of the present invention are sufficiently exhibited, there is no particular limitation.

  Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method using a static mixer described in Chapter 8 of Nienow's “Liquid Mixing Technology” (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

8) Surfactant Surfactants applicable to the present invention are described in paragraph No. 0132 of JP-A No. 11-65021.
In the present invention, it is preferable to use a fluorochemical surfactant. Preferable specific examples of the fluorosurfactant include compounds described in JP-A Nos. 10-197985, 2000-19680, 2000-214554 and the like. Further, a polymeric fluorine-based surfactant described in JP-A-9-281636 is also preferably used.
In the present invention, the use of a fluorosurfactant described in Japanese Patent Application No. 2000-206560 is particularly preferred.

9) Antistatic agent In the present invention, an antistatic layer containing various known metal oxides or conductive polymers may be provided. The antistatic layer may also serve as the above-described undercoat layer, back layer surface protective layer, or the like, or may be provided separately. Regarding the antistatic layer, paragraph No. 0135 of JP-A No. 11-65021, paragraphs of JP-A Nos. 56-143430, 56-143431, 58-62646, No. 56-120519, and paragraphs of JP-A No. 11-84573. The techniques described in Paragraph Nos. 0078 to 0084 of Nos. 0040 to 0051, US Pat. No. 5,575,957 and JP-A-11-223898 can be applied.

10) Support The transparent support is subjected to heat treatment in a temperature range of 130 ° C to 185 ° C in order to relieve internal strain remaining in the film during biaxial stretching and to eliminate heat shrinkage strain generated during heat development processing. Polyester, especially polyethylene terephthalate, is preferably used.

In the case of a photothermographic material for medical use, the transparent support may be colored with a blue dye (for example, dye-1 described in Examples of JP-A-8-240877) or may be uncolored.
Specific examples of the support are described in paragraph No. 0134 of JP-A No. 11-65021.

  Examples of the support include water-soluble polyesters disclosed in JP-A-11-84574, styrene-butadiene copolymers described in JP-A-10-186565, and vinylidene chloride described in JP-A-2000-39684 and Japanese Patent Application No. 11-106881, paragraph numbers 0063 to 0080. It is preferable to apply an undercoating technique such as a copolymer.

11) Other additives An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid may be further added to the photothermographic material. A solvent described in paragraph No. 0133 of JP-A No. 11-65021 may be added. Various additives are added to either the photosensitive layer or the non-photosensitive layer. With respect to these, WO 98/36322, EP 803764A1, JP-A-10-186567, 10-18568 and the like can be referred to.

12) Coating method The photothermographic material in the invention may be coated by any method. Specifically, various coating operations including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. And Stephen F. Kistler, Peter M. et al. The extrusion coating described in “LIQUID FILM COATING” (CHAPMAN & HALL, 1997) by Schweizer (1997), pages 399 to 536 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. 11b. 1 If desired, two or more layers can be simultaneously coated by the method described on pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent No. 837,095. .

The organic silver salt-containing layer coating solution in the present invention is preferably a so-called thixotropic fluid. Regarding this technique, JP-A-11-52509 can be referred to.
The viscosity of the organic silver salt-containing layer coating solution in the present invention is preferably 400 mPa · s or more and 100,000 mPa · s or less, more preferably 500 mPa · s or more and 20,000 mPa · s or less, at a shear rate of 0.1 S ⁻¹ .
Further, at a shear rate of 1000 S ⁻¹ , 1 mPa · s to 200 mPa · s is preferable, and 5 mPa · s to 80 mPa · s is more preferable.

13) Packaging material The photothermographic material of the present invention is used to prevent deterioration of photographic performance during storage before use, or to prevent curling or curling in the case of a rolled product form. It is preferable to hermetically package with a packaging material having low oxygen permeability and / or moisture permeability. The oxygen permeability is preferably 50 ml / atm / m ² · day or less at 25 ° C., more preferably 10 ml / atm / m ² · day or less, and even more preferably 1.0 ml / atm / m ² · day. day or less. The moisture permeability is preferably 10 g / atm / m ² · day or less, more preferably 5 g / atm / m ² · day or less, and further preferably 1 g / atm / m ² · day or less. As specific examples of the packaging material having low oxygen permeability and / or moisture permeability, those described in, for example, JP-A-8-254793 and JP-A-2000-206653 can be used.

14) Other technologies that can be used Techniques that can be used in the photothermographic material of the present invention include EP80364A1, EP883022A1, WO98 / 36322, JP-A-56-62648, JP-A-58-62644, and JP-A-5-62644. 9-43766, 9-281737, 9-297367, 9-304869, 9-31405, 9-329865, 10-10669, 10-62899, 10-69023 10-186568, 10-90823, 10-171603, 10-186565, 10-186567, 10-186567 to 10-186572, 10-197974, Nos. 10-197982, 10-197983, 10-197985 to 1 No. 0-197987, No. 10-207001, No. 10-207004, No. 10-221807, No. 10-282601, No. 10-288823, No. 10-288824, No. 10-307365, No. 10- No. 312038, No. 10-339934, No. 11-7100, No. 11-15105, No. 11-24200, No. 11-24201, No. 11-30832, No. 11-84574, No. 11-65021 11-109547, 11-125880, 11-129629, 11-133536 to 11-133539, 11-133542, 11-133543, 11-223898, 11-352627, 11-305377, 11-305378, 11-305 84, 11-305380, 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, Japanese Patent Application 2000-187298 JP, 2001-200414, 2001-234635, 2002-20699, 2001-275471, 2001-275461, 2000-313204, 2001-292844, 2000-324888. 2001-293864 and 2001-348546.

15) Color imaging The composition of a multicolor photothermographic material may include a combination of these two layers for each color, and within a single layer as described in US Pat. No. 4,708,928. May contain all the components.
In the case of a multicolor color photothermographic material, each emulsion layer is generally a functional or non-functional barrier layer between each photosensitive layer as described in U.S. Pat. No. 4,460,681. Are used to keep them distinguished from each other.

2. Image forming method 2-1. Exposure The photothermographic material of the present invention may be a “single-sided type” having an image forming layer only on one side of a support or a double-sided type having image forming layers on both sides.
(Double-sided photothermographic material)
The photothermographic material of the present invention can be preferably used in an image forming method for recording an X-ray image using an X-ray intensifying screen.
The process of forming an image using these photothermographic materials comprises the following processes.
(A) a step of obtaining an image forming assembly by installing the photothermographic material between a pair of X-ray intensifying screens;
(B) placing a subject between the assembly and the X-ray source;
(C) irradiating the subject with X-rays having an energy level in the range of 25 kVp to 125 kVp;
(D) removing the photothermographic material from the assembly;
(E) A step of heating the photothermographic material taken out at a temperature in the range of 90 ° C to 180 ° C.

  In the photothermographic material of the present invention, an image obtained by stepwise exposure using X-rays and heat development is a characteristic curve on orthogonal coordinates where the optical axis (D) and exposure amount (log E) are equal in unit length. The average gamma (γ) formed by the minimum density (Dmin) + density 0.1 point and the minimum density (Dmin) + density 0.5 point is 0.5 to 0.9, and the minimum density (Dmin) It is prepared so as to have a characteristic curve in which the average gamma (γ) formed by the point of + density 1.2 and the minimum density (Dmin) + density 1.6 is 3.2 to 4.0. preferable. In the X-ray imaging system of the present invention, when a photothermographic material having such a characteristic curve is used, an X-ray image having excellent photographic characteristics such that the legs are extremely extended and the gamma is high in the medium density portion. Is obtained. Due to this photographic characteristic, the description of the low density region such as the mediastinum with a small amount of X-ray transmission and heart shadow is good, and the density becomes easy to see even in the image of the lung field with a large amount of X-ray transmission. In addition, there is an advantage that the contrast becomes good.

  The photothermographic material having the preferable characteristic curve as described above can be easily obtained by, for example, a method in which each of the image forming layers on both sides is composed of two or more silver halide emulsion layers having different sensitivities. Can be manufactured. In particular, it is preferable to form an image forming layer using a high-sensitivity emulsion for the upper layer and an emulsion having low sensitivity and high photographic characteristics for the lower layer. When such an image forming layer comprising two layers is used, the difference in sensitivity of the silver halide emulsions between the respective layers is 1.5 to 20 times, preferably 2 to 15 times. The ratio of the amount of emulsion used to form each layer varies depending on the sensitivity difference and covering power of the emulsion used. In general, the larger the sensitivity difference, the lower the usage ratio of the emulsion on the high sensitivity side. For example, when the difference in sensitivity is double, the preferable ratio of each emulsion is 1:20 or more and 1:50 or less as a high-sensitivity emulsion and a low-sensitivity emulsion in terms of silver when the covering power is almost equal. Prepared to be in the range of values.

  The technique of crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material) is described in JP-A-2-68539, page 13, lower left column, line 1 to page 14, lower left column, line 9; Dyes or dyes and mordants can be used.

  Next, the fluorescent intensifying screen (radiation intensifying screen) of the present invention will be described. The radiation intensifying screen includes, as a basic structure, a support and a phosphor layer formed on one side thereof. The phosphor layer is a layer in which a phosphor is dispersed in a binder. In general, a transparent protective film is provided on the surface of the phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is chemically altered or Protects against physical shock.

In the present invention, preferred phosphors include those shown below. Tungstate phosphors (CaWO ₄ , MgWO ₄ , CaWO ₄ : Pb, etc.), terbium activated rare earth oxysulfide phosphors [Y ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, (Y, Gd) O ₂ S: Tb, Tm, etc.], terbium-activated rare earth phosphate phosphors (YPO ₄ : Tb, GdPO ₄ : Tb, LaPO ₄ : Tb, etc.), terbium activated rare earth oxyhalide phosphors (LaOBr: Tb, LaOBr: Tb, Tm, LaOCl: Tb, LaOCl: Tb, Tm, LaOBr: Tb, GdOBr: Tb, GdOCl: Tb, etc.) , Thulium activated rare earth oxyhalide phosphors (LaOBr: Tm, LaOCl: Tm, etc.), barium sulfate phosphors [BaSO ₄ : Pb, BaSO ₄ : Eu ²⁺ , (Ba , Sr) SO ₄ : Eu ²⁺ etc.], divalent europium activated alkaline earth metal phosphate phosphor [(Ba ₂ PO ₄ ) ₂ : Eu ²⁺ , (Ba ₂ PO ₄ ) ₂ : Eu ²⁺ Etc.] Divalent europium activated alkaline earth metal fluoride halide phosphor [BaFCl: Eu ²⁺ , BaFBr: Eu ²⁺ , BaFCl: Eu ²⁺ , Tb, BaFBr: Eu ²⁺ , Tb, BaF ₂ BaCl · KCl: Eu ²⁺ , (Ba, Mg) F ₂ .BaCl · KCl: Eu ²⁺ etc.], iodide phosphors (CsI: Na, CsI: Tl, NaI, KI: Tl etc.), sulfide Physical phosphors [ZnS: Ag (Zn, Cd) S: Ag, (Zn, Cd) S: Cu, (Zn, Cd) S: Cu, Al, etc.], hafnium phosphate phosphors (HfP ₂ O ₇ : Cu, etc.), was also added various activator as YTaO ₄ and the light emission center to it . However, the phosphor used in the present invention is not limited to these, and any phosphor that emits light in the visible or near ultraviolet region when irradiated with radiation can be used.

In the X-ray fluorescent intensifying screen more preferably used in the present invention, 50% or more of emitted light has a wavelength of 350 nm or more and 420 nm or less. In particular, the phosphor is preferably a divalent Eu-activated phosphor, and more preferably a divalent Eu-activated barium halide phosphor. The emission wavelength region is preferably 360 nm to 420 nm, more preferably 370 nm to 420 nm. More preferably, the fluorescent screen has light emission of 70% or more, more preferably 85% or more in the same region.
The ratio of the emitted light is calculated by the following method. That is, the emission spectrum is measured with the emission wavelength on the horizontal axis at equal intervals with a true number and the number of emitted photons on the vertical axis. A value obtained by dividing the area of 350 nm to 420 nm on this chart by the area of the entire emission spectrum is defined as the ratio of light emitted at a wavelength of 350 nm to 420 nm. By having light emission at such a wavelength, high sensitivity can be achieved in combination with the photothermographic material of the present invention.

  In order to have most of the emitted light of the phosphor in such a wavelength range, it is preferable that the half width of the emitted light is narrow. The preferred half-value width is 1 nm to 70 nm, more preferably 5 nm to 50 nm, and still more preferably 10 nm to 40 nm.

  The phosphor to be used is not particularly limited as long as such light emission is obtained. However, in order to achieve high sensitivity, which is the object of the present invention, the phosphor may be an Eu-activated phosphor having a divalent Eu as the emission center. The preferred present invention is not limited to this.

BaFCl: Eu, BaFBr: Eu, BaFI: Eu and their halogen compositions are changed, BaSO ₄ : Eu, SrFBr: Eu, SrFCl: Eu, SrFI: Eu, (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu, SrB ₄ O ₇ F: Eu, SrMgP ₂ O ₇ : Eu, Sr ₃ (PO ₄ ) ₂ : Eu, Sr ₂ P ₂ O ₇ : Eu can be used.

A more preferable phosphor is a divalent Eu-activated barium halide phosphor represented by the general formula MX ₁ X ₂ : Eu. Here, M contains Ba as a main component, but it is possible to preferably contain a small amount of other compounds such as Mg, Ca and Sr. X ₁ and X ₂ are halogen atoms, and can be arbitrarily selected from F, Cl, Br, and I. Here, X ₁ is preferably fluorine. X ₂ can be selected from Cl, Br, and I, and a mixture of some of these halogen compositions can also be preferably used. More preferably, X = Br. Eu is europium. Eu as the emission center is preferably contained at a ratio of 10 ^{−7 to} 0.1 with respect to Ba. More preferably, it is 10 ⁻⁴ or more and 0.05 or less. It is also preferable to mix a small amount of other compounds. Most preferred phosphors include BaFCl: Eu, BaFBr: Eu, and BaFBr _1-X I _X : Eu.

The fluorescent intensifying screen is preferably composed of a support, an undercoat layer on the support, a phosphor layer, and a surface protective layer.
The phosphor layer is prepared by dispersing the phosphor layer in an organic solvent solution containing the phosphor particles and a binder resin, and then dispersing the dispersion into a support (an undercoat layer such as a light reflection layer on the support). Can be formed by directly coating and drying on the subbing layer). Alternatively, after applying this dispersion on a separately prepared temporary support and drying to form a phosphor sheet, the phosphor sheet is peeled off from the temporary support and attached to the support using an adhesive. May be.

  There is no restriction | limiting in particular in the particle size of fluorescent substance particle, Usually, it is the range of about 1 micrometer-15 micrometers, Preferably it is the range of about 2 micrometers-10 micrometers. The volume filling rate of the phosphor particles in the phosphor layer is preferably higher, usually in the range of 60% to 85%, preferably in the range of 65% to 80%, particularly preferably 68% to 75%. Range. (The ratio of the phosphor particles in the phosphor layer is usually 80% by mass or more, preferably 90% by mass or more, and particularly preferably 95% by mass or more.) Binder resin used for forming the phosphor layer, organic Solvents and various additives that can optionally be used are described in various known documents. The thickness of the phosphor layer can be arbitrarily set according to the target sensitivity, but is preferably in the range of 70 μm to 150 μm for the front side screen and in the range of 80 μm to 400 μm for the back side screen. . The X-ray absorption rate of the phosphor layer is determined by the amount of phosphor particles applied.

  The phosphor layer may be a single layer or may be composed of two or more layers. One to three layers are preferable, and one or two layers are more preferable. For example, layers composed of phosphor particles having a relatively narrow particle size distribution and different particle sizes may be laminated. In that case, the layer closer to the support may have a smaller particle size. In particular, it is preferable to apply phosphor particles having a large particle size to the surface protective layer side, and to apply phosphor particles having a small particle size to the support side, and those having a small particle size are 0.5 μm to 2.0 μm. The thing of a particle size has the preferable range of 10 micrometers-30 micrometers. Further, phosphor layers having different particle diameters may be mixed to form a phosphor layer, or in Japanese Patent Publication No. 55-33560, page 3, left column, line 3 to page 4, left column, line 39. As described, the phosphor layer may have a structure in which the particle size distribution of the phosphor particles is inclined. Usually, the variation coefficient of the particle size distribution of the phosphor is in the range of 30 to 50%, but monodispersed phosphor particles having a variation coefficient of 30% or less can also be preferably used.

Efforts are made to produce a preferable sharpness by dyeing the phosphor layer with respect to the emission wavelength. However, a layer design with as little dyeing as possible is preferably used. The absorption length of the phosphor layer is preferably 100 μm or more, more preferably 1000 μm or more.
The scattering length is preferably designed to be 0.1 μm or more and 100 μm or less. More preferably, it is 1 μm or more and 100 μm or less. The scattering length and the absorption length can be calculated by a calculation formula based on the Kubelka-Munk theory described later.

  As the support, it can be appropriately selected from various supports used for known radiation intensifying screens according to the purpose. For example, a polymer film containing a white pigment such as titanium dioxide or a polymer film containing a black pigment such as carbon black is preferably used. An undercoat layer such as a light reflecting layer containing a light reflecting material may be provided on the surface of the support (the surface on the side where the phosphor layer is provided). A light reflecting layer as described in JP-A-2001-124898 is also preferably used. In particular, the light reflecting layer made of yttrium oxide described in Patent Example 1 and the light reflecting layer described in Patent Example 4 are preferably used. As for a preferred light reflecting layer, the description of JP-A 23001-124898, from the third term on the 15th line on the right to the fourth term on the right on the 23rd line can be referred to.

  A surface protective layer is preferably provided on the surface of the phosphor layer. The light scattering length measured at the main emission wavelength of the phosphor is preferably in the range of 5 μm to 80 μm, more preferably in the range of 10 μm to 70 μm, and particularly preferably in the range of 10 μm to 60 μm. Here, the light scattering length represents an average distance in which light travels straight before being scattered once, and the shorter the scattering length, the higher the light scattering property. Further, the light absorption length representing the average free distance until light is absorbed is arbitrary, but from the viewpoint of screen sensitivity, it is preferable that the surface protective layer does not absorb because the desensitization is less. In order to make up for the lack of scattering, it is possible to provide a slight absorption. The absorption length is preferably 800 μm or more, particularly preferably 1200 μm or more. The light scattering length and the light absorption length can be calculated by a calculation formula based on the Kubelka-Munk theory using the measured values measured by the following method.

  First, three or more film samples having the same composition as the surface protective layer to be measured and having different layer thicknesses are prepared. Next, the thickness (μm) and diffuse transmittance (%) of each film sample are measured. The diffuse transmittance can be measured by a device in which an integrating sphere is attached to a normal spectrophotometer. In the measurement in the present invention, a 150φ integrating sphere (150-0901) is attached to a self-recording spectrophotometer (U-3210, manufactured by Hitachi, Ltd.). The measurement wavelength needs to match the peak wavelength of the main light emission of the phosphor of the target phosphor layer to which the surface protective layer is attached. Next, the measured value of the film thickness (μm) and diffuse transmittance (%) are introduced into the following formula (A) derived from Kubelka-Munk's theoretical formula. Formula (A) can be obtained, for example, from “Phosphor Handbook” (edited by Fluorescent Materials Association, Ohm Co., Ltd., published in 1987), page 403, formulas 5 · 12 · 5 · 5 · 15 and diffuse transmittance T ( %) Can be easily derived under boundary conditions.

  Where T is the diffuse transmittance (%), d is the film thickness (μm), and α and β are defined by the following equations, respectively.

  T (diffusion transmittance:%) and d (film thickness: μm) measured for three or more films are respectively introduced into the above equation (A), and K and S satisfying the equation (A) are calculated. The scattering length (μm) is defined by 1 / S and the absorption length (μm) is defined by 1 / K.

  The surface protective layer preferably has a structure in which light scattering particles are dispersed and contained in a resin material. The light refractive index of the light-scattering particles is usually 1.6 or more, preferably 1.9 or more. The particle diameter of the light scattering particles is usually in the range of 0.1 μm to 1.0 μm. Examples of such light-scattering particles include aluminum oxide, magnesium oxide, zinc oxide, zinc sulfide, titanium oxide, niobium oxide, barium sulfate, lead carbonate, silicon oxide, polymethyl methacrylate, styrene, and melamine fine particles. Can be mentioned.

  The resin material used for forming the surface protective layer is not particularly limited, but polyethylene terephthalate, polyethylene naphthalate, polyamide, aramid, fluororesin, polyester, and the like can be preferably used. The surface protective layer is prepared by dispersing the light scattering particles in an organic solvent solution containing a resin material (binder resin), and then preparing the dispersion on the phosphor layer (or any auxiliary material). It can be formed by coating and drying directly (through the layer). Or you may attach the sheet | seat for protective layers formed separately on the fluorescent substance layer using an adhesive agent. The thickness of the surface protective layer is usually in the range of 2 μm to 12 μm, and preferably in the range of 3.5 μm to 10 μm.

  Furthermore, for a preferred method for producing a radiation intensifying screen and materials used therefor, for example, JP-A-9-21899, page 6, left column, line 47 to page 8, left column, line 5, JP-A-6-347598. There are detailed descriptions in the second page, right column, line 17 to page 3, left column, line 33, and the third page, left column, line 42 to page 4, left column, line 22 of the publication. be able to.

  The fluorescent intensifying screen used in the present invention is preferably filled with a phosphor with an inclined particle size structure. In particular, it is preferable to apply phosphor particles having a large particle size to the surface protective layer side, and to apply phosphor particles having a small particle size to the support side, and those having a small particle size are 0.5 μm to 2.0 μm. The thing of a particle size has the preferable range of 10 micrometers-30 micrometers.

(Single-sided photothermographic material)
The single-sided photothermographic material of the present invention is particularly preferably used as a mammographic X-ray photosensitive material.
In the single-sided photothermographic material used for this purpose, it is important to design the contrast of the obtained image within an appropriate range.

  With respect to preferable constitutional requirements as an X-ray photosensitive material for mammography, the descriptions in JP-A-5-45807, JP-A-10-62881, JP-A-10-54900, and JP-A-11-109564 can be referred to. .

(Single-sided photothermographic material)
The single-sided photothermographic material of the present invention is particularly preferably used as a mammographic X-ray photosensitive material.
In the single-sided photothermographic material used for this purpose, it is important to design the contrast of the obtained image within an appropriate range.

  With respect to preferable constitutional requirements as an X-ray photosensitive material for mammography, the descriptions in JP-A-5-45807, JP-A-10-62881, JP-A-10-54900, and JP-A-11-109564 can be referred to. .

(Combination with ultraviolet fluorescent screen)
As an image forming method using the photothermographic material of the present invention, a method of forming an image by combining with a phosphor having a main peak preferably at 400 nm or less can be used. More preferably, a method of forming an image in combination with a phosphor having a main peak at 380 nm or less is preferable. Either a double-sided sensitive material or a single-sided sensitive material can be used as an assembly. As the screen having a main emission peak at 400 nm or less, the screens described in JP-A-6-11804 and WO93 / 01521 are used, but not limited thereto. As a technique of ultraviolet crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material), the technique described in JP-A-8-76307 can be used. As the ultraviolet absorbing dye, the dye described in JP-A No. 2001-144030 is particularly preferable.

2-2. Thermal Development The photothermographic material of the present invention may be developed by any method, but is usually developed by raising the temperature of the photothermographic material exposed imagewise. The preferred development temperature is 90 ° C to 180 ° C, more preferably 100 ° C to 140 ° C.
The development time is preferably 1 second to 60 seconds, more preferably 5 seconds to 30 seconds, and particularly preferably 5 seconds to 20 seconds.

  A plate heater method is preferred as the heat development method. The heat development method using the plate heater method is preferably a method described in JP-A-11-133572. The heat development photosensitive material on which a latent image is formed is brought into contact with a heating means in a heat development part, and heat for obtaining a visible image. In the developing device, the heating unit includes a plate heater, and a plurality of press rollers are disposed to face each other along one surface of the plate heater, and the heat is interposed between the press roller and the plate heater. A thermal development apparatus that performs thermal development by passing a development photosensitive material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature of the tip portion by about 1 ° C. to 10 ° C.

  Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and rapidly develop the photothermographic material. It is also possible to suppress changes in the shape of the support of the photothermographic material due to heating of the photothermographic material.

2-3. System Fuji Medical Dry Imager-FM-DPL can be mentioned as a medical laser imager provided with an exposure unit and a thermal development unit. The system is Fuji Medical Review No. 8, pages 39 to 55, and these techniques can be used. Further, it can also be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Medical Co., Ltd. as a network system conforming to the DICOM standard.

3. Use of the present invention The photothermographic material using the high silver iodide photographic emulsion 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, and printing. It is preferably used as a photothermographic material or a photothermographic material for COM.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1.
(Preparation of PET support)
1) Film formation Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) is obtained according to a conventional method. It was. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to prepare an unstretched film.

This was longitudinally stretched 3.3 times using rolls with different peripheral speeds, and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends, and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

2) Surface corona treatment Using a solid state corona treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at 20 m / min at room temperature. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

3) Undercoat <Preparation of undercoat layer coating solution>
Formula 1 (for image forming layer side undercoat)
・ Pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd. 46.8 g
・ Toyobo Co., Ltd. Bironal MD-1200 10.4 g
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 1% by weight solution 11.0 g
・ MP-1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
・ 931 ml of distilled water

Formula 2 (for back layer 1st layer)
・ Styrene-butadiene copolymer latex 130.8 g
(Solid content 40% by mass, styrene / butadiene mass ratio = 68/32)
2,4-Dichloro-6-hydroxy-S-triazine sodium salt
8% by weight aqueous solution 5.2g
・ 10% 1% aqueous solution of sodium laurylbenzenesulfonate
・ Polystyrene particle dispersion (average particle size 2 μm, 20 mass%) 0.5 g
-854 ml of distilled water

Formula 3 (for back layer 2nd layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.5 μm, 17 mass% dispersion)
84g
・ Gelatin 7.9g
・ Shin-Etsu Chemical Co., Ltd. Metros TC-5 (2 mass% aqueous solution) 10g
・ 10% 1% aqueous solution of sodium dodecylbenzenesulfonate
・ NaOH (1% by mass) 7 g
・ Proxel (Abyssia) 0.5g
・ Distilled water 881ml

After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating solution formulation 1 is applied on one side (image forming layer surface) with a wire bar in a wet coating amount of 6.6 ml. / M ² (per one side) and dried at 180 ° C. for 5 minutes, and then the undercoat coating solution formulation 2 is applied to the back side (back side) with a wire bar at a wet coating amount of 5.7 ml / m ^2. And then dried at 180 ° C. for 5 minutes, and further, the undercoat coating solution formulation 3 is applied to the back surface (back surface) with a wire bar so that the wet coating amount is 8.4 ml / m ² . An undercoat support was prepared by drying at 0 ° C. for 6 minutes.

(Back layer)
1) Preparation of back layer coating solution (preparation of solid fine particle dispersion (a) of base precursor)
Add 2.5 kg of Base Precursor Compound 1 and 300 g of a surfactant (trade name: Demol N, manufactured by Kao Corporation), 800 g of diphenylsulfone, 1.0 g of benzoisothiazolinone sodium salt and distilled water to make a total amount. The mixture was mixed to 8.0 kg, and the mixed solution was dispersed with beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation). In the dispersion method, the mixed solution was fed to UVM-2 filled with zirconia beads having an average diameter of 0.5 mm by a diaphragm pump, and dispersed at an internal pressure of 50 hPa or more until a desired average particle size was obtained.
The dispersion was subjected to spectral absorption measurement, and the ratio of the absorbance at 450 nm to the absorbance at 650 nm (D ₄₅₀ / D ₆₅₀ ) in the spectral absorption of the dispersion was dispersed to 3.0. The obtained dispersion was diluted with distilled water so that the concentration of the base precursor was 25% by mass, and was filtered for removal of dust (polypropylene filter having an average pore size of 3 μm) for practical use.

2) Preparation of Dye Solid Fine Particle Dispersion 6.0 kg of cyanine dye compound-1 and 3.0 kg of sodium p-dodecylbenzenesulfonate, 0.6 kg of surfactant Demol SNB manufactured by Kao Corporation, and antifoaming agent (trade name) : Surfynol 104E, manufactured by Nissin Chemical Co., Ltd.) 0.15 kg was mixed with distilled water to make a total liquid volume of 60 kg. The mixed solution was dispersed with 0.5 mm zirconia beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation).
The dispersion was dispersed until the ratio of the absorbance at 650 nm to the absorbance at 750 nm (D ₆₅₀ / D ₇₅₀ ) in the spectral absorption of the dispersion was 5.0 or more. The obtained dispersion was diluted with distilled water so that the concentration of the cyanine dye was 6% by mass, and was subjected to filter filtration (average pore diameter: 1 μm) for removal of dust and put to practical use.

3) Preparation of antihalation layer coating solution Keep the container at 40 ° C., add 37 g of gelatin with an isoelectric point of 6.6 (ABA gelatin manufactured by Nippi Co., Ltd.), 0.1 g of benzoisothiazolinone and water to add gelatin. Dissolved. Further, 36 g of the dye solid fine particle dispersion, 73 g of the solid fine particle dispersion (a) of the base precursor, 43 ml of 3% by weight aqueous sodium polystyrenesulfonate solution, SBR latex (styrene / butadiene / acrylic acid copolymer; mass ratio 68. 3 / 28.7 / 3.0) 82 g of a 10% by mass solution was mixed to prepare a coating solution for the antihalation layer having a finished solution amount of 773 ml. The pH value of the finished liquid was 6.3.

4) Preparation of back surface protective layer coating solution Keep the container at 40 ° C., add 43 g of gelatin with an isoelectric point of 4.8 (PZ gelatin made by Miyagi Chemical Co., Ltd.), 0.21 g of benzoisothiazolinone and water. The gelatin was dissolved. Furthermore, 8.1 ml of 1 mol / l sodium acetate aqueous solution, 0.93 g of monodisperse poly (ethylene glycol dimethacrylate-co-methyl methacrylate) fine particles (average particle size 7.7 μm, particle size standard deviation 0.3 μm), liquid paraffin 5 g of 10 mass% emulsion, 10 g of 10 mass% emulsion of dipentaerythritol hexaisostearate, 10 ml of 5% aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, 17 ml of 3% aqueous solution of polystyrene sodium sulfonate, 2.4 ml of 2% by weight fluorine-based surfactant (F-1) solution, 2.4 ml of 2% by weight solution of fluorine-based surfactant (F-2), ethyl acrylate / acrylic acid copolymer (copolymerization weight) Ratio 96.4 / 3.6) 30 ml of latex 20% by weight solution was mixed. Immediately before coating, 50 ml of a 4% by weight aqueous solution of N, N-ethylenebis (vinylsulfone acetamide) was mixed to prepare a back surface protective layer coating solution having a finished liquid amount of 855 ml. The pH value of the finished liquid was 6.2.

4) Application of back layer On the back surface side of the undercoat support, the coating amount of the antihalation layer coating solution is 0.54 g / m ^2, and the coating amount of the back surface protective layer coating solution is 1 A simultaneous multi-layer coating was applied so as to be .85 g / m ² , followed by drying to prepare a back layer.

(Image forming layer, intermediate layer, and surface protective layer)
1. Preparation of coating materials 1) Silver halide emulsion << Preparation of silver halide emulsion 1 >>
A solution containing 3.1 ml of 1% by weight potassium bromide solution in 1421 ml of distilled water, 3.5 ml of 0.5 mol / L sulfuric acid, and 21.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 35 ° C., distilled water was added to 22.22 g of silver nitrate and distilled to 95.4 ml of solution A, 15.3 g of potassium bromide and 0.8 g of potassium iodide in a distilled water volume of 97.4 ml. The whole amount of the solution B diluted to 1 was added at a constant flow rate over 45 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% by mass aqueous solution of benzimidazole was further added. Further, a solution C in which distilled water was added to 51.86 g of silver nitrate to be diluted to 317.5 ml, a solution D in which 44.2 g of potassium bromide and 2.2 g of potassium iodide were diluted with distilled water to a volume of 400 ml was added to solution C. Was added at a constant flow rate over 20 minutes, and solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of the solution C and the solution D so as to be 1 × 10 ⁻⁴ mol per mol of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / 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.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁴ mol was added and aged for 91 minutes.
Thereafter, a methanol solution having a molar ratio of the spectral sensitizing dye A and the sensitizing dye B of 3: 1 was added in an amount of 1.2 × 10 ⁻³ mol as a total of the sensitizing dyes A and B per mol of silver. , N′-dihydroxy-N ″ -diethylmelamine in 1.3 ml of a 0.8 wt% methanol solution was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4.8 per mole of silver. × 10 ⁻³ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution to 5.4 × 10 ⁻³ mol and 1- (3-methyl) with respect to 1 mol of silver A silver halide emulsion 1 was prepared by adding 8.5 × 10 ⁻³ mol of ureidophenyl) -5-mercaptotetrazole in an aqueous solution to 1 mol of silver.

  The grains in the silver halide emulsion thus prepared were silver iodobromide grains containing 3.5 mol% of iodine having a mean sphere equivalent diameter of 0.045 μm and a sphere equivalent diameter variation coefficient of 20%. The particle size and the like were determined from an average of 1000 particles using an electron microscope. The {100} face ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of silver halide emulsion 2 >>
In the preparation of silver halide emulsion 1, the liquid temperature 30 ° C. during grain formation was changed to 48 ° C., and solution B was changed to diluting 15.9 g of potassium bromide with distilled water to a volume of 97.4 ml, Solution D was changed to diluting 45.8 g of potassium bromide with distilled water to a volume of 400 ml, and the addition time of solution C was changed to 30 minutes to remove potassium hexacyanoiron (II) in the same manner. A silver halide emulsion 2 was prepared. Precipitation / desalting / washing / dispersion was carried out in the same manner as silver halide emulsion 1. Furthermore, the addition amount of tellurium sensitizer C is 1.1 × 10 ⁻⁴ mol per mol of silver, and the addition amount of methanol solution of 3: 1 in the molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is silver. The total of sensitizing dye A and sensitizing dye B per mole is 7.0 × 10 ⁻⁴ mole, and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole is added to 1 mole of silver. Same as Emulsion 1 except that 3.3 × 10 ⁻³ mol and 1- (3-methylureidophenyl) -5-mercaptotetrazole were changed to 4.7 × 10 ⁻³ mol added to 1 mol of silver. Spectral sensitization, chemical sensitization, and addition of 5-methyl-2-mercaptobenzimidazole and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole were carried out to obtain silver halide emulsion 2. . The emulsion grains of the silver halide emulsion 2 were pure silver bromide cubic grains having an average sphere equivalent diameter of 0.083 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of silver halide emulsion 3 >>
In the preparation of silver halide emulsion 1, silver halide emulsion 3 was prepared in the same manner except that the liquid temperature at the time of grain formation was changed from 30 ° C. to 26 ° C. Further, precipitation / desalting / washing / dispersion was performed in the same manner as silver halide emulsion 1. The molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is 1: 1 as a solid dispersion (gelatin aqueous solution), and the addition amount is 6 × 10 ⁻ as the total of sensitizing dye A and sensitizing dye B per mole of silver. ³ moles, the amount of tellurium sensitizer C added was changed to 5.2 × 10 ⁻⁴ moles per mole of silver, and bromoauric acid was changed to 5 × 10 ⁻⁴ moles of silver 3 minutes after the addition of tellurium sensitizers. A silver halide emulsion 3 was obtained in the same manner as Emulsion 1 except that 2 × 10 ⁻³ mol of mol and potassium thiocyanate were added per mol of silver. 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 0.033 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of mixed emulsion A for coating solution >>
70% by weight of silver halide emulsion 1, 15% by weight of silver halide emulsion 2 and 15% by weight of silver halide emulsion 3 were dissolved, and 7% by mole of silver in a 1% by weight aqueous solution of benzothiazolium iodide. × 10 ^-3 mol was added.
Furthermore, the amount of the one-electron oxidant produced by one-electron oxidation is 2 × 10 ⁻³ moles per mole of silver halide of each compound 1, 2, and 3 capable of emitting one electron or more. Added.
As an adsorptive redox compound having an adsorbing group and a reducing group, compounds were added as shown in Table 1 to prepare coating solutions A to G.
Further, water was added so that the content of silver halide per 1 kg of the mixed emulsion for coating solution was 38.2 g as silver. 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added so as to give 0.34 g per kg of the mixed emulsion for coating solution.

2) Preparation of fatty acid silver dispersion << Preparation of fatty acid silver dispersion >>
Henkel behenic acid (product name Edenor C22-85R) 87.6 kg, distilled water 423 L, 5 mol / L NaOH aqueous solution 49.2 L, t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react. A sodium behenate solution A was obtained.
Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution A and the total amount of the aqueous silver nitrate solution were each maintained at a constant flow rate for 93 minutes 15 Added over seconds and 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution A is started. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant.
The pipe of the addition system of the sodium behenate solution A was prepared by keeping warm water by circulating hot water outside the double pipe so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution A and the addition position of the aqueous silver nitrate solution were arranged symmetrically around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of the sodium behenate solution A, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 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 microscope photography, the average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter. It was a scaly crystal having a coefficient of variation of 0.52 μm and a sphere equivalent diameter of 15%. (A, b, and c are the text provisions)

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to 1260 kg / cm ² by adjusting the pressure of the disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

3) Preparation of reducing agent dispersion << Preparation of reducing agent-1 dispersion >>
10 kg of water was added to 10 kg of a reducing agent-1 (2,2′-methylenebis- (4-ethyl-6-tert-butylphenol)) 10 kg and a 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Add and mix well to make a slurry. This slurry was fed with a diaphragm pump, dispersed for 3 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent 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 Reducing Agent-2 Dispersion >>
10 mass of reducing agent-2 (6,6′-di-t-butyl-4,4′-dimethyl-2,2′-butylidenediphenol) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour, and then further heated at 80 ° C. for 1 hour to obtain a reducing agent-2 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.50 μm and a maximum particle diameter of 1.6 μm or less.
The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of hydrogen bonding compound-1 dispersion 10 kg of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of the aqueous solution and mixed well to obtain a slurry.
This slurry was fed with a diaphragm pump, and dispersed for 4 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare a hydrogen bonding compound concentration of 25% by mass.
This dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less.
The obtained hydrogen bonding 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.

5) Preparation of Development Accelerator-1 Dispersion 10 kg of Development Accelerator-1 and 20 kg of 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added with 10 kg of water and mixed well. To make a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the development accelerator to 20% by mass to obtain a development accelerator-1 dispersion. The development accelerator particles contained in the development accelerator dispersion thus obtained had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The obtained development accelerator dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
6) Preparation of Dispersion of Development Accelerator-2 and Color Adjuster-1 The solid dispersion of Development Accelerator-2 and Color Adjuster-1 was also dispersed by the same method as Development Accelerator-1, each having 20 mass. %, 15% by mass of a dispersion liquid was obtained.

7) Preparation of polyhalogen compound << Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (tribromomethanesulfonylbenzene), 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry.
This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass to obtain an organic polyhalogen compound-1 dispersion. The organic polyhalogen compound particles contained in the 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 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of an organic polyhalogen compound-2 (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by mass aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20 of sodium triisopropylnaphthalenesulfonate 0.4 kg of a mass% aqueous solution was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 30% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-2 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.3 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.

8) Preparation of phthalazine compound-1 solution >>
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 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate and 70 mass of phthalazine compound-1 (6-isopropylphthalazine). 14.28 kg of a% aqueous solution was added to prepare a 5% by mass solution of phthalazine compound-1.

9) Preparation of mercapto compound)
<< Preparation of Mercapto Compound-1 Aqueous Solution >>
7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.

<< Preparation of Mercapto Compound-2 Aqueous Solution >>
20 g of mercapto compound-2 (1- (3-methylureidophenyl) -5-mercaptotetrazole) was dissolved in 980 g of water to obtain a 2.0 mass% aqueous solution.

10) Preparation of Pigment-1 Dispersion C.I. I. Pigment Blue 60 (64 g) and Kao Corp. Demol N (6.4 g) were added to 250 g of water and mixed well to obtain a slurry. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and disperse with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) for 25 hours. A pigment-1 dispersion was obtained by adjusting the concentration to 5% by mass. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

11) Preparation of SBR latex liquid SBR latex (TP-1) was prepared as follows.
In a polymerization kettle of a gas monomer reactor (TAS-2J type manufactured by Pressure Glass Industrial Co., Ltd.), 287 g of distilled water and a surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)): solid content 48.5 (Mass%) 7.73 g, 1 mol / liter NaOH 14.06 ml, ethylenediaminetetraacetic acid tetrasodium salt 0.15 g, styrene 255 g, acrylic acid 11.25 g, tert-dodecyl mercaptan 3.0 g, the reaction vessel was sealed and the stirring speed was Stir at 200 rpm. After degassing with a vacuum pump and repeating nitrogen gas replacement several times, 108.75 g of 1,3-butadiene was injected and the internal temperature was raised to 60 ° C. A solution prepared by dissolving 1.875 g of ammonium persulfate in 50 ml of water was added thereto, and the mixture was stirred as it was for 5 hours.
The temperature was further raised to 90 ° C., and the mixture was stirred for 3 hours. After completion of the reaction, the internal temperature was lowered to room temperature, and then Na ⁺ ion: NH ₄ ⁺ ion = 1: 1 using 1 mol / L NaOH and NH ₄ OH. Addition treatment was performed so that the molar ratio was 5.3 (molar ratio), and the pH was adjusted to 8.4. Thereafter, the mixture was filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored, and 774.7 g of SBR latex TP-1 was obtained. When the halogen ions were measured by ion chromatography, the chloride ion concentration was 3 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 145 ppm.

  The latex has an average particle size of 90 nm, Tg = 17 ° C., solid content concentration of 44 mass%, equilibrium moisture content at 25 ° C. and 60% RH, 0.6 mass%, ion conductivity of 4.80 mS / cm (measurement of ion conductivity is The conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd. was used and measured at 25 ° C.).

12) Preparation of isoprene latex liquid Isoprene latex (TP-2) was prepared as follows.
Add 1500 g of distilled water to the polymerization kettle of the gas monomer reactor (Pressure Glass Industry Co., Ltd. TAS-2J type), heat at 90 ° C. for 3 hours, and passivate to the stainless steel surface of the polymerization kettle and members of the stainless steel stirring device A film is formed. In this polymerized kettle, 582.28 g of distilled water bubbled with nitrogen gas for 1 hour, 9.49 g of surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)), 1 mol / L NaOH Of ethylenediaminetetraacetic acid tetrasodium salt 0.20 g, styrene 314.99 g, isoprene 190.87 g, acrylic acid 10.43 g, tert-dodecyl mercaptan 2.09 g, and the reaction vessel was sealed and stirred at 225 rpm. The mixture was stirred and heated to an internal temperature of 65 ° C. A solution prepared by dissolving 2.61 g of ammonium persulfate in 40 ml of water was added thereto, and the mixture was stirred as it was for 6 hours. At this time, the polymerization conversion rate was 90% from the measurement of the solid content. Here, a solution in which 5.22 g of acrylic acid was dissolved in 46.98 g of water was added, 10 g of water was subsequently added, and a solution in which 1.30 g of ammonium persulfate was dissolved in 50.7 ml of water was further added. After the addition, the temperature was raised to 90 ° C. and stirred for 3 hours. After the reaction was completed, the internal temperature was lowered to room temperature, and then Na ⁺ ions: NH ₄ ⁺ ions were used with 1 mol / L NaOH and NH ₄ OH. = 1: 5.3 (molar ratio) was added and adjusted to pH 8.4.
Thereafter, the mixture was filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored, and 1248 g of isoprene latex TP-2 was obtained. When the halogen ions were measured by ion chromatography, the chloride ion concentration was 3 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 142 ppm.

  The latex has an average particle size of 113 nm, Tg = 15 ° C., solid content concentration of 41.3 mass%, equilibrium water content at 25 ° C. and 60% RH of 0.4 mass%, ionic conductivity of 5.23 mS / cm (of ionic conductivity). Measurement was conducted at 25 ° C. using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd.).

2. Preparation of coating solution 1) Preparation of coating solution for image forming layer 1000 g of fatty acid silver dispersion obtained above, 135 ml of water, 35 g of pigment-1 dispersion, 19 g of organic polyhalogen compound-1 dispersion, and organic polyhalogen compound-2 dispersion 58 g, 162 g of phthalazine compound-1 solution, 424 g of SBR latex (TP-1) solution, 636 g of isoprene latex (TP-2) solution, 75 g of reducing agent-1 dispersion, 75 g of reducing agent-2 dispersion, hydrogen bonding compound- 53 g of 1 dispersion, 4.8 g of development accelerator-2 dispersion, 9 ml of mercapto compound-1 aqueous solution, and 27 ml of mercapto compound-2 aqueous solution were added sequentially, and 118 g was added to silver halide mixed emulsions A to G immediately before coating. The well-mixed image forming layer coating solution was directly fed to the coating die and applied.

The viscosity of the image forming layer coating solution was 28 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 38 ° C. using a Haake RheoStress RS150 is 37, 40, 38, 30, 19 [mPa · s] at shear rates of 0.1, 1, 10, 100, and 1000 [1 / second], respectively. s].
The amount of zirconium in the coating solution was 0.32 mg per 1 g of silver.

2) Preparation of intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 163 g of pigment-1 dispersion, blue dye compound-1 (manufactured by Nippon Kayaku Co., Ltd .: Kayafect Turquoise RN Liquid 150) ) 33 g of 18.5 wt% aqueous solution, 27 ml of 5 wt% aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 57/8) / 28/5/2) 4200 ml of latex 19 wt% solution, 27 ml of 5 wt% aqueous solution of aerosol OT (American Cyanamid Co., Ltd.), 135 ml of 20 wt% aqueous solution of diammonium phthalate, total amount 10000 g So that the pH is 7.5. The intermediate layer coating solution was adjusted with OH and fed to the coating die so as to be 8.9 ml / m ² .
The viscosity of the coating solution was 58 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3) Preparation of surface protective layer first layer coating solution 100 g of inert gelatin and 10 mg of benzoisothiazolinone were dissolved in 840 ml of water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio) 57/8/28/5/2) Latex 19% by weight solution 180g, phthalic acid 15% by weight methanol solution 46ml, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5% by weight aqueous solution 5.4ml was added. The mixture was mixed, and immediately before coating, 40 ml of 4% by weight chromium alum was mixed with a static mixer and fed to the coating die so that the amount of the coating solution was 26.1 ml / m ² .
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of surface protective layer second layer coating solution 100 g of inert gelatin and 10 mg of benzoisothiazolinone are dissolved in 800 ml of water, 10 g of a 10% by weight emulsion of liquid paraffin, and 10% by weight of dipentaerythritol hexaisostearate. 30 g of emulsion, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) latex 19% by weight liquid 180 g, phthalic acid 15% by weight methanol 40 ml of solution, 5.5 ml of 1% by weight solution of fluorosurfactant (F-1), 5.5 ml of 1% by weight aqueous solution of fluorosurfactant (F-2), di (2-ethylhexyl sulfosuccinate) ) 28 ml of a 5% by weight aqueous solution of sodium salt, polymethyl methacrylate fine particles (average A mixture of 4 g of particle size 0.7 μm, volume weighted average distribution 30%) and 21 g of polymethyl methacrylate fine particles (average particle size 3.6 μm, volume weighted average distribution 60%) is used as a surface protective layer coating solution. The solution was fed to the coating die so as to be 3 ml / m ² .
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3. Preparation of photothermographic material 1) Preparation of photothermographic material Apply slide beads in the order of the image forming layer, intermediate layer, surface protective layer first layer, surface protective layer second layer from the undercoat surface to the surface opposite to the back surface. Samples 1-1 to 1-7 of photothermographic materials were prepared by simultaneous multi-layer coating by the method. At this time, the coating solution for the image forming layer and the intermediate layer was adjusted to 31 ° C., the coating solution for the first surface protective layer was adjusted to 36 ° C., and the coating solution for the second surface protective layer was adjusted to 37 ° C.
The coating amount (g / m ² ) of each compound in the image forming layer is as follows.

Fatty acid silver 5.22
Pigment (C.I. Pigment Blue 60) 0.036
Polyhalogen compound-1 0.12
Polyhalogen compound-2 0.30
Phthalazine Compound-1 0.18
SBR latex (TP-1) 3.88
Isoprene latex (TP-2) 5.82
Reducing agent-1 0.40
Reducing agent-2 0.40
Hydrogen bonding compound-1 0.116
Development accelerator-2 0.02
Mercapto Compound-1 0.002
Mercapto compound-2 0.010
Silver halide (as Ag) 0.13

The coating and drying conditions are as follows.
The coating was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 mm to 0.30 mm, and the pressure in the decompression chamber was set to be 196 Pa to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating.
In the subsequent chilling zone, the coating liquid is cooled with a wind at a dry bulb temperature of 10 ° C. to 20 ° C., then transported in a non-contact manner, and dried at a dry bulb temperature of 23 ° C. to 45 ° C. It dried with the drying wind of 15 degreeC and the wet-bulb temperature of 15 to 21 degreeC.
After drying, the humidity was adjusted at 25 ° C. and humidity of 40% RH to 60% RH, and then the film surface was heated to 70 ° C. to 90 ° C. After heating, the film surface was cooled to 25 ° C.
The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the image forming layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the image forming layer surface side was measured and found to be 6.0.

The chemical structures of the compounds used in the examples of the present invention are shown below.

4). Evaluation of photographic performance 1) Preparation The obtained sample was cut into half-cut size (43 cm length x 35 cm width), packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, and stored at room temperature for 2 weeks. The following evaluation was performed.
<Packaging materials>
Laminate film consisting of PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% by mass of carbon:
Oxygen permeability: 0.02 ml / atm · m ² · 25 ° C · day;
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day.

2) Exposure / development of photosensitive material Photothermographic material-1 is exposed and thermally developed (112 ° C.) with Fuji Medical Co., Ltd. dry laser imager FM-DPL (mounted with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)). -119 ° C-121 ° C-121 ° C with four panel heaters for a total of 24 seconds), and the obtained image was evaluated with a densitometer.

3) Evaluation of photographic performance (sensitivity)
A characteristic curve of the density with respect to the exposure amount and logarithm was plotted, and the sensitivity was represented by the reciprocal of the exposure amount giving a density of fog +0.5, and the sensitivity of the sample 1-1 was expressed as a relative value. Higher values are preferable because of higher sensitivity.
(Cover)
The density of the portion not exposed to light was fogged and expressed as Dmin.
(Sensitivity during short-time development)
Increase the development speed, set the passage time of 4 panel heaters at 112 ° C-119 ° C-121 ° C-121 ° C to 10 seconds, and the difference in sensitivity from the setting of 24 seconds (ΔS = LogE (24 seconds)- The difference in LogE (10 seconds) was expressed by ΔS. A smaller value of ΔS is preferable because a sensitive material can be obtained in a short time.
(Sample storability)
The sample packaged as described above was stored at 40 ° C. for 1 month, then returned to room temperature and subjected to the same exposure and development as described above. The difference between the fog after aging and the fog before aging was expressed as ΔDmin. A smaller value of ΔDmin is preferable because there is no change in photographic properties over time.

As shown in Table 1, it can be seen that the compound of the present invention is preferable although it has a high sensitivity and a low covering, and the sensitivity difference between 10-second development and 24-second development and the increase in fog during storage are small.
In addition, the above-described increase in fog during storage and the difference in sensitivity between 10-second development and 24-second development cannot be realized with a comparative compound that is a mercapto-adsorbing group, and can only be realized by the present invention.
Example 2

The following back surface application was performed on a PET support that had been undercoated in the same manner as in Example 1.
(Preparation of back surface coating solution)

<Preparation of antihalation layer coating solution 32.7 g of lime-processed gelatin in water kept at 40 ° C., 0.77 g of monodisperse polymethyl methacrylate fine particles (average particle size 8 μm, particle size standard deviation 0.4 μm), benzoisothiazolinone 0.08 g, polystyrene polystyrene sodium 0.3 g, blue dye compound-1 0.06 g, ultraviolet light absorber-1 1.5 g, acrylic acid / ethyl acrylate copolymer latex (copolymerization ratio 5/95) 5 0.0 g, 1.7 g of N, N-ethylenebis (vinylsulfone acetamide) are mixed, pH is adjusted to 6.0 with 1 mol / l sodium hydroxide, and the whole is made up to 818 ml with water. A liquid was prepared.

(Preparation of back surface protective layer coating solution)
66.5 g of lime-processed gelatin in water kept at 40 ° C., 5.4 g of liquid paraffin emulsion as liquid paraffin, 0.10 g of benzoisothiazolinone, 0.5 g of sodium di (2-ethylhexyl) sulfosuccinate, polystyrene sulfonic acid 0.27 g of sodium, 13.6 mL of a 2% aqueous solution of a fluorosurfactant (F-1), 10.0 g of acrylic acid / ethyl acrylate copolymer (copolymerization mass ratio 5/95) were mixed, and 1 mol / L The pH was adjusted to 6.0 with sodium hydroxide and made up to 1000 ml with water to obtain a back surface protective layer coating solution.

(Application of back layer)
On the back surface side of the undercoat support, the gelatin application amount of the antihalation layer coating solution is 1.70 g / m ^2, and the back surface protection layer coating solution is 0.79 g / m ² . A multi-layer was simultaneously applied and dried to form a back layer.
(Image forming layer, intermediate layer, and surface protective layer)
1. Preparation of coating materials 1) Preparation of silver halide emulsion << Preparation of silver halide emulsion 4 >>
To a solution of 1420 ml of distilled water was added 4.3 ml of a 1% by weight potassium iodide solution, and a solution containing 3.5 ml of 0.5 mol / L sulfuric acid and 36.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 40 ° C., a solution A in which distilled water was added to 22.22 g of silver nitrate and diluted to 195.6 ml and solution B in which 21.8 g of potassium iodide was diluted to 218 ml in volume with distilled water at a constant flow rate. The whole amount was added over 9 minutes. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% by mass aqueous solution of benzimidazole was further added.

Further, Solution C obtained by adding distilled water to 51.86 g of silver nitrate and diluting to 317.5 ml and Solution D obtained by diluting 60 g of potassium iodide to a volume of 600 ml with distilled water were added to Solution C over 120 minutes at a constant flow rate. Solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / 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.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in methanol solution to a ratio of 2. 9 × 10 ⁻⁴ mol was added and aged for 91 minutes.
1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and after 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4. Halogenation by adding 8 × 10 ⁻³ mol and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in a methanol solution to 5.4 × 10 ⁻³ mol with respect to 1 mol of silver Silver emulsion 4 was prepared.

  Grains in the prepared silver halide emulsion were pure silver iodide grains having an average sphere equivalent diameter of 0.038 μm and a sphere equivalent diameter variation coefficient of 18%. Moreover, it is a tetrahedral particle | grain which has (001), {100}, {101} face, The ratio of the (gamma) phase was 30% when measured using the X ray powder diffraction analysis. The particle size and the like were determined from an average of 1000 particles using an electron microscope.

<< Preparation of silver halide emulsion 5 >>
The temperature of the reaction solution was changed to 60 ° C., 5 ml of a 5% methanol solution of 2,2 ′-(ethylenedithio) diethanol was added after the addition of solutions A and B, and solution D while maintaining pAg at 10.5 Was added by the controlled double jet method, and 3 minutes after addition of the tellurium sensitizer at the time of chemical sensitization, 5 × 10 ^-4 moles of bromothermic acid per mole of silver and potassium thiocyanate 2 per mole of silver. A silver halide emulsion 5 was prepared in the same manner as the emulsion 4 except that × 10 ^-3 mol was added.
The grains in the prepared silver halide emulsion have a projected area average equivalent circle diameter of 0.164 μm, a grain thickness of 0.030 μm, an average aspect ratio of 5, an average spherical equivalent diameter of 0.11 μm, and a coefficient of variation of the equivalent spherical diameter of 23. % Pure silver iodide tabular grains. When measured using X-ray powder diffraction analysis, the proportion of the γ phase was 80%. The particle size and the like were determined from an average of 1000 particles using an electron microscope.
<< Preparation of silver halide emulsion 6 >>
Silver halide emulsion 6 in exactly the same manner as silver halide emulsion 4 except that the temperature of the reaction solution was changed to 25 ° C. and solution D was added by the controlled double jet method while maintaining pAg at 10.2. Was made.
The grains in the prepared silver halide emulsion were pure silver iodide grains having an average sphere equivalent diameter of 0.020 μm and a sphere equivalent diameter variation coefficient of 17%. Further, they were dodecahedron grains having (001), {1 (-1) 0}, and {101} planes, and were silver iodide substantially consisting of a β phase as measured by X-ray powder diffraction analysis. The particle size and the like were determined from an average of 1000 particles using an electron microscope.

<< Preparation of silver halide emulsions 4 ', 5', 6 ', 4 ", 5", and 6 ">>
For each of silver halides 4, 5, and 6, silver halides 4 ′, 5 ′, which have the same size as silver halides 4, 5, 6 and have an AgI content of 85% by performing conversion with KBr, Silver halides 4 ″, 5 ″ and 6 ″ having a content of 6 ′ and AgI of 50% were prepared, respectively.
<< Preparation of mixed emulsion B1 for coating solution >>
Silver halide emulsion 4, silver halide emulsion 5 and silver halide emulsion 6 were dissolved in a silver molar ratio of 5: 2: 3, and benzothiazolium iodide was added in a 1% by mass aqueous solution of silver 1 7 × 10 ⁻³ moles were added per mole.
Further, the amount of the one-electron oxidant produced by one-electron oxidation is 2 × 10 ⁻³ moles per mole of silver halide, each of compounds 1, 2, and 3 capable of emitting one electron or more. Added. A compound having an adsorbing group and a reducing group was added to this mixed solution as shown in Table 2.
Further, water was added so that the silver halide content per liter of the mixed emulsion for coating solution was 15.6 g as silver.

<< Preparation of mixed emulsions B2 and B3 for coating solutions >>
Coating emulsions B2 and B3 were prepared in the same manner as coating emulsion B1 using silver halide emulsions 4′5′6 ′ and 4 ″, 5 ″, and 6 ″.

2) Preparation of fatty acid silver dispersion <Preparation of recrystallized behenic acid>
100 kg of behenic acid (product name Edenor C22-85R) manufactured by Henkel was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 30 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour. The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then dried. When the obtained crystals were esterified and subjected to GC-FID measurement, the behenic acid content was 96 mol%, and in addition, lignoceric acid was 2 mol%, arachidic acid was 2 mol%, and erucic acid was 0.001 mol%. It was.
<Preparation of fatty acid silver dispersion>
Recrystallized behenic acid 88 kg, distilled water 422 L, 5 mol / L NaOH aqueous solution 49.2 L and t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react to obtain sodium behenate solution B. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient agitation, the total amount of the previous sodium behenate solution and the total amount of silver nitrate aqueous solution were kept at a constant flow rate of 93 minutes and 15 seconds, respectively. And added over 90 minutes.
At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. It was made to be.
At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant.
The pipe of the addition system for the sodium behenate solution was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution 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 around the stirring axis, and were adjusted so as not to contact the reaction solution.

After completion of the addition of the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 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 microscope photography, the average values were a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, average aspect ratio 2.1, and equivalent sphere diameter. The crystal had a coefficient of variation of 11%. (A, b, and c are the text provisions)

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to a pressure of 1150 kg / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

2. Preparation of coating solution 1) Preparation of image forming layer coating solution Pigment-1 dispersion, organic polyhalogen compound-1 dispersion, organic polyhalogen compound-2 dispersion in 1000 g of the fatty acid silver dispersion obtained above and 276 ml of water, Phthalazine compound-1 solution, SBR latex (Tg: 17 ° C.) liquid, reducing agent-1 dispersion, reducing agent-2 dispersion, hydrogen bonding compound-1 dispersion, development accelerator-1 dispersion, development accelerator -2 Dispersion, Color Modifier-1 Dispersion, Mercapto Compound-1 Aqueous Solution, Mercapto Compound-2 Aqueous Solution are added in order, and mixed emulsions B1 to B3 for coating solution are added and mixed well immediately before coating, and coating is performed as it is. The solution was fed to the die and applied.

The viscosity of the image forming layer coating solution was 25 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is 242, 65, 48 at shear rates of 0.1, 1, 10, 100, and 1000 [1 / second], respectively. 26 and 20 [mPa · s].

  The amount of zirconium in the coating solution was 0.52 mg per 1 g of silver.

2) Preparation of intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 272 g of pigment-1 dispersion, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass) Ratio 64/9/20/5/2) 27 ml of 5% by weight aqueous solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.) in 4200 ml of 19% by weight latex, 135 ml of 20% by weight aqueous solution of diammonium phthalate salt, Water was added so that the total amount was 10,000 g, and it was adjusted with NaOH so that the pH was 7.5 to obtain an intermediate layer coating solution, which was fed to the coating die so as to be 9.1 ml / m ² .
The viscosity of the coating solution was 58 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3) Preparation of surface protective layer first layer coating solution 64 g of inert gelatin was dissolved in water and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 112 g of latex 19.0 wt% solution, 30 ml of 15 wt% methanol solution of phthalic acid, 23 ml of 10 wt% aqueous solution of 4-methylphthalic acid, 28 ml of 0.5 mol / L sulfuric acid, Aerosol OT (American 5 ml of a 5% by weight aqueous solution (made by Cyanamid), 0.5 g of phenoxyethanol, and 0.1 g of benzoisothiazolinone are added to form a coating solution by adding water to a total amount of 750 g. 26 ml of 4% by weight chromium alum consisting of which had been mixed with a static mixer to 18.6ml / m ² to immediately before coating It was fed to a coating die.
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of surface protective layer second layer coating solution 80 g of inert gelatin was dissolved in water and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 102 g of latex 27.5% by mass solution, 5.4 ml of 2% by mass solution of fluorosurfactant (F-1), and 5% by mass of 2% by mass aqueous solution of fluorosurfactant (F-2). 4 ml, 23 ml of a 5% by mass solution of aerosol OT (manufactured by American Cyanamid), 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm, volume weighted average distribution 30%), polymethyl methacrylate fine particles (average particle) Diameter 3.6 μm, volume weighted average distribution 60%) 21 g, 4-methylphthalic acid 1.6 g, phthalic acid 4.8 g, 0.5 mol / L concentration Water was added to 44 ml of sulfuric acid and 10 mg of benzoisothiazolinone to a total amount of 650 g, and 445 ml of an aqueous solution containing 4% by weight chromium alum and 0.67% by weight phthalic acid was mixed with a static mixer immediately before coating. The liquid was fed to the coating die so as to be 8.3 ml / m ² .
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3. Preparation of photothermographic material Simultaneously multilayer coating by slide bead coating method in the order of image forming layer, intermediate layer, surface protective layer first layer, surface protective layer second layer from the undercoat surface to the surface opposite to the back surface, A sample of the photothermographic material was prepared.
At this time, the image forming layer and the intermediate layer were adjusted to 31 ° C., the first surface protective layer was adjusted to 36 ° C., and the second surface protective layer was adjusted to 37 ° C.

The coating amount (g / m ² ) of each compound in the image forming layer is as follows.
Fatty acid silver 5.27
Pigment of Example 1 (CI Pigment Blue 60) 0.036
Polyhalogen compound-1 of Example 1 0.09
Polyhalogen compound-2 of Example 1 0.14
Phthalazine Compound-1 of Example 1 0.18
SBR latex of Example 1 9.43
Reducing agent-1 of Example 1 0.55
Reducing agent-2 of Example 1 0.22
Hydrogen bonding compound-1 of Example 1 0.28
Development Accelerator-1 of Example 1 0.025
Development Accelerator-2 of Example 1 0.020
Color tone adjusting agent-1 of Example 1 0.008
Mercapto Compound-1 of Example 1 0.002
Mercapto compound-2 of Example 1 0.006
Silver halide (as Ag) 0.046

The coating and drying conditions are as follows.
The support was neutralized with ion wind before coating, and coating was performed at a speed of 160 m / min. The coating and drying conditions were adjusted within the following ranges for each sample, and were set to conditions that would provide the most stable surface shape.
The gap between the coating die tip and the support is 0.10 mm to 0.30 mm.
The pressure in the decompression chamber is set to 196 Pa to 882 Pa lower than the atmospheric pressure.
In the subsequent chilling zone, the coating solution is cooled with wind at a dry bulb temperature of 10 ° C to 20 ° C.
It is transported in a non-contact manner and dried with a dry air having a dry bulb temperature of 23 ° C. to 45 ° C. and a wet bulb temperature of 15 ° C. to 21 ° C. in a helical contact type non-contact dryer.
After drying, humidity is adjusted at 25 ° C. and humidity 40% RH-60% RH.
Subsequently, the film surface was heated to 70 ° C. to 90 ° C., and after the heating, the film surface was cooled to 25 ° C.

  The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the image forming layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the image forming layer surface side was measured and found to be 6.0.

(Evaluation of photographic performance)
The obtained sample was cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows.
(Packaging material)
Laminate film in which PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% by mass of carbon is laminated:
Oxygen permeability: 0.02 ml / atm · m ² · 25 ° C · day;
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day.

As a sample, an NLHV3000E semiconductor laser manufactured by Nichia Corporation was mounted as a semiconductor laser light source on the exposure part of a dry laser imager DRYPIX7000 of FUJIFILM Medical Co., Ltd., and the beam diameter was reduced to 100 μm. The illuminance on the photosensitive material surface of the laser light was exposed at 10 ^-6 seconds varied between 0 and ^{1mW / mm 2 ~1000mW / mm 2} .
The oscillation wavelength of the laser beam was 405 nm. In the heat development, three panel heaters were set at 107 ° C.-121 ° C.-121 ° C. and developed so that the total time was 14 seconds.
The obtained image was evaluated with a densitometer.

(Sample evaluation)
The same samples as in Example 1 were evaluated and the results shown in Table 2 were obtained. The difference Δ between the sensitivity when the three heaters are passed in 14 seconds and the sensitivity when the heaters are passed in 8 seconds is ΔS.

As is apparent from Table 2, it was found that the compounds of the present invention showed a small increase in sensitivity due to fluctuations in development time and a small increase in fog during storage. Also, the effect is large compared to Example 1, and it can be seen that the effect of the present invention appears remarkably in the case of a high silver iodide emulsion.
Further, it was found that particularly when the silver iodide content is high, the use of the compound of the present invention can further suppress an increase in sensitivity due to fluctuations in development time and an increase in fogging during storage.

Example 3
A heat-developable photosensitive material for photographing on both sides was produced as follows.

1. Preparation of PET support and undercoating 1) Film formation

Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) was obtained according to a conventional method.
This was pelletized and dried at 130 ° C. for 4 hours. The film was colored blue with a blue dye (1,4-bis (2,6-diethylanilinoanthraquinone), then extruded from a T-die and quenched to prepare an unstretched film.

This was longitudinally stretched 3.3 times using rolls with different peripheral speeds, and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends, and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

2) Surface corona treatment Using a solid state corona treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at 20 m / min at room temperature. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

3) Preparation of undercoat support (1) Preparation formulation of undercoat layer coating solution (1) (for photosensitive layer side undercoat layer)
84 g of SnO ₂ / SbO (9/1 mass ratio, average particle size 0.5 μm, 17 mass% dispersion)
46.8 g of pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Bailonal MD-1200 10.4g manufactured by Toyobo Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average number of ethylene oxides = 8.5) 1% by weight solution 11.0 g
MP-1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
847 ml of distilled water

After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating solution formulation (1) is applied with a wire bar to a wet coating amount of 6.6 ml / m ² (single side And then dried at 180 ° C. for 5 minutes, and this was applied to both sides to prepare an undercoat support.

2. Preparation of coating materials 1) Silver halide emulsion (Preparation of silver halide emulsion a)
4.3 ml of 1% by weight potassium iodide solution is added to 1421 ml of distilled water, and 3.5 ml of 0.5 mol / L sulfuric acid, 36.5 g of phthalated gelatin, and 5 mass of 2,2 ′-(ethylenedithio) diethanol. The solution to which 160 ml of a methanol solution was added was stirred in a stainless steel reaction vessel while maintaining the liquid temperature at 77 ° C., and 222.02 g of silver nitrate was added with distilled water and diluted to 218 ml with potassium iodide 36. Solution B in which 6 g was diluted to 366 ml with distilled water was added in a total amount over 16 minutes at a constant flow rate, and solution B was added by the control double jet method while maintaining pAg at 10.2. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% by mass aqueous solution of benzimidazole was further added.
Further, a solution C in which distilled water was added to 51.86 g of silver nitrate and diluted to 508.2 ml, and a solution D in which 63.9 g of potassium iodide were diluted to 639 ml with distilled water, and solution C was added at a constant flow rate over 80 minutes. The whole amount was added, and Solution D was added by the control double jet method while maintaining pAg at 8.5. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver.
Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / 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 11.0.

  The silver halide emulsion a is a pure silver iodide emulsion having an average projected area diameter of 0.58 μm, an average projected area diameter variation coefficient of 15.7%, an average thickness of 0.149 μm, and an average aspect ratio of 4.2. Tabular grains having an aspect ratio of 2 or more accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.45 μm. As a result of analysis by X-ray powder diffraction analysis, 30% or more of silver iodide was present in the γ phase.

<< Preparation of silver halide emulsion b >>
One mole of tabular grain AgI emulsion prepared with silver halide emulsion a was placed in a reaction vessel. The pAg was 10.2 measured at 38 ° C. Then, by double jet addition, 0.5 mol / liter KBr solution and 0.5 mol / liter AgNO ₃ solution were added at 10 ml / min over 20 minutes, and substantially 10 mol% silver bromide was added to the AgI host. Epitaxially precipitated on the emulsion. During operation, pAg was maintained at 7.2. Further, the pH was adjusted to 3.8 using sulfuric acid having a concentration of 0.5 mol / L, stirring was stopped, and a precipitation / 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 11.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁵ mol was added and aged for 91 minutes. Thereafter, 1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and further 4 minutes later, 5-methyl-2-mercaptobenzimidazole was added with methanol solution per mole of silver. 4.8 × 10 ⁻³ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole was added in methanol solution to 5.4 × 10 ⁻³ mol and 1- ( Silver halide emulsion b was prepared by adding 8.5 × 10 ⁻³ mol of 3-methylureidophenyl) -5-mercaptotetrazole in an aqueous solution to 1 mol of silver.

<< Preparation of silver halide emulsion c >>
A solution obtained by adding 8 ml of a 10% by weight potassium iodide solution to 1421 ml of distilled water and further adding 4.6 g of phthalated gelatin and 160 ml of a 5% by weight methanol solution of 2,2 ′-(ethylenedithio) diethanol is made of stainless steel. While stirring in the reaction vessel, the liquid temperature was maintained at 77 ° C., and solution A in which distilled water was added to 22.7 g of silver nitrate and diluted to 223 ml and solution B in which 36.6 g of potassium iodide were diluted to 366 ml with distilled water were Solution A was added at a constant flow rate over 15 minutes and 22 seconds, and Solution B was added by the control double jet method while maintaining pAg at 9.96.
Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 0.8 ml of a 10% by mass aqueous solution of benzimidazole was further added. Further, Solution C obtained by adding distilled water to 53.1 g of silver nitrate to dilute to 520.2 ml and Solution D obtained by diluting 63.9 g of potassium iodide to 639 ml with distilled water were added over 80 minutes at a constant flow rate. The whole amount was added, and Solution D was added by the control double jet method while maintaining pAg at 8.4. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver.
Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / 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 11.0.

  The obtained host grain is a pure silver iodide emulsion having an average projected area diameter of 0.980 μm, an average projected area diameter variation coefficient of 16.3%, an average thickness of 0.243 μm, and an average aspect ratio of 4.2, Tabular grains having an aspect ratio of 2 or more accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.70 μm. As a result of analysis by X-ray powder diffraction analysis, 15% or more of silver iodide was present in the γ phase.

<Preparation of silver halide emulsion d>
One mole of the above AgI host particles was placed in a reaction vessel. The pAg was 9.1 measured at 40 ° C. Then, by double jet addition, a halogen solution containing 0.088 mol KBr and 0.038 mol NaCl per liter and a 0.125 mol / liter AgNO ₃ solution at 28.7 ml / min for 31 minutes. When added, an amount of silver chlorobromide in an amount of 10 mol% of the total silver amount was epitaxially precipitated at six corners on the AgI host emulsion. During operation, pAg was maintained at 7.13.
Further, the pH was adjusted to 3.8 using sulfuric acid having a concentration of 0.5 mol / L, stirring was stopped, and a precipitation / 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 11.0.
The average halogen composition of the epitaxial part was obtained by preparing an ultrathin slice of the silver halide grain epitaxial part and obtaining it by a field emission type analytical electron microscope, and found that 80 mol% bromine, 17 mol% chloro and 3 mol% iodine. It was.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% methanol solution of 1,2-benzisothiazolin-3-one was added, and the temperature was raised to 60 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁵ mol was added and aged for 91 minutes. Thereafter, 1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″, N ″ -diethylmelamine was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was dissolved in silver with a methanol solution. 4.8 × 10 ⁻³ mole per mole, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution with 5.4 × 10 ⁻³ mole per mole of silver and 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added in an aqueous solution to 8.5 × 10 ⁻³ mol per mol of silver to prepare a silver halide emulsion d having an epitaxial junction.

<Preparation of silver halides e and f>
In the same manner as silver halide a, silver halide e was prepared by adjusting pAg at the time of adding solution C and solution D to 10.0. The silver halide emulsion e is a pure silver iodide emulsion having an average projected area diameter of 0.815 μm, an average projected area diameter variation coefficient of 17.9%, an average thickness of 0.093 μm, and an average aspect ratio of 8.8. Tabular grains having an aspect ratio of 2 or more accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.45 μm. As a result of analysis by X-ray powder diffraction analysis, 30% or more of silver iodide was present in the γ phase. Silver halide f was prepared using silver halide e in the same manner as silver halide b.

<Preparation of silver halides g and h>
Similarly to the silver halide c, the pAg when adding the solution C and the solution D was adjusted to 10.0 to prepare silver halide g.
The obtained host grain is a pure silver iodide emulsion having an average projected area diameter of 1.342 μm, an average projected area diameter variation coefficient of 18.3%, an average thickness of 0.125 μm, and an average aspect ratio of 10.5, Tabular grains having an aspect ratio of 2 or more accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.70 μm. As a result of analysis by X-ray powder diffraction analysis, 15% or more of silver iodide was present in the γ phase. Silver halide h was prepared using silver halide g in the same manner as silver halide d.

≪Preparation of mixed emulsion for coating liquid≫
Silver halide emulsion b and silver halide emulsion d, or silver halide f and silver halide h were dissolved in an amount of 5: 1 as a silver molar ratio at 60 ° C. and spectral sensitizing dye 1 as shown in Table 3 Was added at 1.3 × 10 ⁻³ mole per mole of silver and aged for 5 minutes. After cooling to 38 ° C., 7 × 10 ⁻³ mol of benzothiazolium iodide was added as a 1% by mass aqueous solution per mol of silver.
Further, the amount of the compound compounds 1, 2 and 3 that can be emitted by one-electron oxidation by one-electron oxidant to emit one or more electrons is 2 × 10 ⁻³ mol per mol of silver halide. Was added. Further, the compounds shown in Table 3 were added as compounds having an adsorbing group and a reducing group. Water was added so that the silver halide content per liter of the mixed emulsion for coating solution was 15.6 g as silver.

2) Preparation of fatty acid silver dispersion <Preparation of recrystallized behenic acid>
100 kg of behenic acid (product name Edenor C22-85R) manufactured by Henkel was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 30 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour.
The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then dried. When the obtained crystals were esterified and subjected to GC-FID measurement, the behenic acid content was 96 mol%, and in addition, lignoceric acid was 2 mol%, arachidic acid was 2 mol%, and erucic acid was 0.001 mol%. It was.

<Preparation of fatty acid silver dispersion>
Recrystallized behenic acid 88 kg, distilled water 422 L, 5 mol / L NaOH aqueous solution 49.2 L and t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react to obtain sodium behenate solution B. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient agitation, the total amount of the previous sodium behenate solution and the total amount of silver nitrate aqueous solution were kept at a constant flow rate of 93 minutes and 15 seconds, respectively. And added over 90 minutes.
At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. It was made to be. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant.
The pipe of the addition system for the sodium behenate solution was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C.
Moreover, the piping of the addition system of the silver nitrate aqueous solution 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 around the stirring axis, and were adjusted so as not to contact the reaction solution.

After completion of the addition of the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 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 microscope photography, the average values were a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, average aspect ratio 2.1, and equivalent sphere diameter. The crystal had a coefficient of variation of 11%. (A, b, and c are the text provisions)

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to a pressure of 1150 kg / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

3) Preparation of reducing agent dispersion << Preparation of reducing agent-3 dispersion >>
10 mass of reducing agent-3 (1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to obtain a slurry.
This slurry was fed with a diaphragm pump, dispersed for 3 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of nucleating agent dispersion Compound No. 1 was used as a nucleating agent. To 7 g of SH-7, 2.5 g of polyvinyl alcohol (Kuraray PVA-217) and 87.5 g of water were added and stirred well, and left as a slurry for 3 hours. Thereafter, 240 g of 0.5 mm zirconia beads are put in a vessel together with the slurry, and dispersed for 10 hours with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) to prepare a solid fine particle dispersion of a nucleating agent. did. As for the particle size, 80% by mass of the particles was 0.1 μm to 1.0 μm, and the average particle size was 0.5 μm.

3. Preparation of coating solution 1) Preparation of coating solution for image forming layer To 1000 g of the fatty acid silver dispersion obtained above and 276 ml of water, organic polyhalogen compound-1 dispersion, organic polyhalogen compound-2 dispersion, SBR latex (TP- 1) Liquid, isoprene latex (TP-2) liquid, reducing agent-3 dispersion, nucleating agent dispersion, hydrogen bonding compound-1 dispersion, development accelerator-1 dispersion, development accelerator-2 dispersion , Color Tone Modifier-1 Dispersion, Mercapto Compound-1 Aqueous Solution, Mercapto Compound-2 Aqueous Solution were added sequentially, and after adding the silver iodide complex forming agent, the silver halide mixed emulsion for coating solution was silver immediately before coating. In an amount, 0.22 mol was added per 1 mol of fatty acid silver, mixed well, sent as it was to the coating die, and coated.

The viscosity of the image forming layer coating solution was 25 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is 242, 65, 48 at shear rates of 0.1, 1, 10, 100, 1000 [1 / second], respectively. 26, 20 [mPa · s].

  The amount of zirconium in the coating solution was 0.52 mg per 1 g of silver.

2) Preparation of intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20 / 5/2) 27 ml of 5% by weight aqueous solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.) is added to 4200 ml of 19% by weight latex, and NaOH is added so that the total amount becomes 10,000 g. The intermediate layer coating solution was adjusted to 9.1 ml / m ² and fed to the coating die.
The viscosity of the coating solution was 58 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3) Preparation of surface protective layer first layer coating solution 64 g of inert gelatin was dissolved in water and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 112 g of latex 19.0 wt% solution, 30 ml of 15 wt% methanol solution of phthalic acid, 23 ml of 10 wt% aqueous solution of 4-methylphthalic acid, 28 ml of 0.5 mol / L sulfuric acid, Aerosol OT (American 5 ml of a 5% by weight aqueous solution (made by Cyanamid), 0.5 g of phenoxyethanol, and 0.1 g of benzoisothiazolinone are added to form a coating solution by adding water to a total amount of 750 g. 26 ml of 4% by weight chromium alum consisting of which had been mixed with a static mixer to 18.6ml / m ² to immediately before coating It was fed to a coating die.
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of surface protective layer second layer coating solution 80 g of inert gelatin was dissolved in water and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 102 g of latex 27.5% by mass solution, 5.4 ml of 2% by mass solution of fluorosurfactant (F-1), and 5% by mass of 2% by mass aqueous solution of fluorosurfactant (F-2). 4 ml, 23 ml of a 5% by mass solution of aerosol OT (manufactured by American Cyanamid), 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm, volume weighted average distribution 30%), polymethyl methacrylate fine particles (average particle) Diameter 3.6 μm, volume weighted average distribution 60%) 21 g, 4-methylphthalic acid 1.6 g, phthalic acid 4.8 g, 0.5 mol / L concentration Water was added to 44 ml of sulfuric acid and 10 mg of benzoisothiazolinone to a total amount of 650 g, and 445 ml of an aqueous solution containing 4% by weight chromium alum and 0.67% by weight phthalic acid was mixed with a static mixer immediately before coating. The liquid was fed to the coating die so as to be 8.3 ml / m ² .
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4). Preparation of photothermographic material

Sample 3 of the photothermographic material was simultaneously coated on both sides of the support by the slide bead coating method in the order of the image forming layer, the intermediate layer, the first surface protective layer, and the second surface protective layer from the undercoat surface. -1 to 3-13 were produced. At this time, the image forming layer and the intermediate layer were adjusted to 31 ° C., the first surface protective layer was adjusted to 36 ° C., and the second surface protective layer was adjusted to 37 ° C.
Coated silver amount per one side is 0.861 g / m ² in total of the fatty acid silver and silver halide was 1.72 g / m ² in the image forming layer sum together both sides.

The total coating amount (g / m ² ) per side of each compound in the image forming layer is as follows.
Fatty acid silver (as silver) 0.686
Polyhalogen compound-1 0.028
Polyhalogen compound-2 0.094
Silver iodide complex forming agent 0.46
SBR latex 5.20
SBR latex (TP-1) 2.09
Isoprene latex (TP-2) 3.13
Reducing agent-1 0.46
Nucleating agent 0.036
Hydrogen bonding compound-1 0.15
Development accelerator-1 0.005
Development accelerator-2 0.035
Color tone adjusting agent-1 0.002
Mercapto Compound-1 0.001
Mercapto compound-2 0.003
Silver halide (as Ag) 0.175

The coating and drying conditions are as follows.
-The support was neutralized with ion wind before coating, and coating was performed at a speed of 160 m / min. The coating and drying conditions were prepared in the following ranges for each sample, and were set to conditions that yielded the most stable surface shape.
The gap between the coating die tip and the support is 0.10 mm to 0.30 mm.
-The pressure in the decompression chamber is set to 196 Pa to 882 Pa lower than the atmospheric pressure.
-In the subsequent chilling zone, the coating solution is cooled with wind at a dry bulb temperature of 10 ° C to 20 ° C.
-Transported in a non-contact manner and dried with a dry air having a dry bulb temperature of 23 ° C to 45 ° C and a wet bulb temperature of 15 ° C to 21 ° C in a helical contactless dryer.
-After drying, humidity is adjusted at 25 ° C. with a humidity of 40% RH to 60% RH.
-Subsequently, the film surface was heated so that it might become 70 to 90 degreeC, and the film surface was cooled to 25 degreeC after the heating.

  The matte degree of the photothermographic material thus prepared was 250 seconds in terms of Beck smoothness. Further, the pH of the film surface on the image forming layer surface side was measured and found to be 6.0.

  The chemical structure of the compound used in this example is shown below.

5. Performance evaluation (preparation)
The obtained sample was cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows.
<Packaging materials>
Laminate film in which PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% by mass of carbon is laminated:
Oxygen permeability: 0.02 ml / atm · m ² · 25μ · day;
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day.

(exposure)
Two X-ray regular screens HI-B3 (emission peak wavelength: 425 nm) manufactured by FUJIFILM Corporation were used, and a sample was sandwiched between them to produce an image forming assembly. This assembly was subjected to X-ray exposure for 0.05 seconds, and X-ray sensitometry was performed. The X-ray apparatus used was a trade name DRX-3724HD manufactured by Toshiba Corporation, and a tungsten target was used. A voltage of 80 kVp was applied to the three phases by a pulse generator, and X-rays passed through a 7 cm water filter having absorption almost equivalent to that of the human body were used as a light source. The X-ray exposure was changed by the distance method, and step exposure was performed with a width of logE = 0.15.

(Heat development)
The heat development section of the Fuji Medical Dry Laser Imager FM-DPL was modified to produce a heat development machine that can be heated from both sides. In addition, the film was remodeled so that the film sheet could be conveyed by changing the conveyance roller of the heat developing unit to a heat drum. Four panel heaters were set to 112 ° C-119 ° C-119 ° C-121 ° C, and the temperature of the heat drum was set to 120 ° C. The same evaluation as in Example 1 was performed under the setting that the heat development time was 24 seconds in total and the conveyance speed was increased to 14 seconds in total.

As in Example 1, the compound of the present invention is almost equivalent to the mercapto compound in JP-A No. 2004-184430 with respect to the increase in sensitivity and fogging, but increased fogging during storage and short-time treatment. It turns out that it is excellent with respect to the sensitivity fluctuation in.
Moreover, the ratio of the effect of this invention in Example 3 was large with respect to Example 2, and it turned out that the compound of this invention is more effective by the large sized tabular grain. Further, it has been found that the effect of the present invention appears remarkably when a sensitizing dye is used or when particles having a higher aspect ratio are used. These effects could not be achieved with the mercapto compound, and the superiority of the compound of the present invention was confirmed.

Example 4
The coated samples 3-1 to 3-13 prepared in Example 3 were exposed using the fluorescent intensifying screen A shown below instead of the H1-B3 screen used in Example 3. Similarly, it was found that the fogging during storage and the sensitivity change during short-time development were small.

(Preparation of fluorescent intensifying screen A)
1) Preparation of undercoat layer In the same manner as in Example 4 of Japanese Patent Application Laid-Open No. 2001-124898, a light reflecting layer having a dried film thickness of 50 μm formed of alumina powder is formed on a 250 μm polyethylene terephthalate (support). did.

2) Production of phosphor sheet BaFBr: Eu phosphor (average particle size 3.5 μm) 250 g, polyurethane binder resin (manufactured by Dainippon Ink and Chemicals, trade name: Pandex T5265M) 8 g, epoxy binder resin (Oilized Shell Epoxy Co., Ltd., trade name: Epicoat 1001) 2 g and isocyanate compound (Japan Polyurethane Industry Co., Ltd., trade name: Coronate HX) 0.5 g were added to methyl ethyl ketone and dispersed with a propeller mixer. A phosphor layer forming coating solution having a viscosity of 25 PS (25 ° C.) was prepared. This coating solution was applied to the surface of a temporary support (polyethylene terephthalate sheet previously coated with a silicone-based release agent) and dried to form a phosphor layer. The phosphor layer was peeled off from the temporary support to obtain a phosphor sheet.

3) Attaching the phosphor sheet on the light reflecting layer The above phosphor sheet is superimposed on the surface of the light reflecting layer of the support with the light reflecting layer produced in the above step 1), and the pressure is 400 kgw with a calender roll. A pressure was applied under the conditions of / cm ² and a temperature of 80 ° C., and a phosphor layer was provided on the light reflection layer. The thickness of the obtained phosphor layer was 125 μm, and the volume filling factor of the phosphor particles in the phosphor layer was 68%.

4) Formation of surface protective layer A polyester adhesive was applied to one side of polyethylene terephthalate (PET) having a thickness of 6 μm, and a surface protective layer was provided on the phosphor layer by a laminating method. Thus, a fluorescent intensifying screen A comprising a support, a light reflecting layer, a phosphor layer, and a surface protective layer was obtained.

5) Luminescent characteristics The emission spectrum of the fluorescent intensifying screen A measured with X-rays of 40 kVp is shown in FIG.
The fluorescent intensifying screen A emitted light with a narrow half-value width having a peak at 390 nm.

The emission spectrum of the fluorescent intensifying screen A is shown.

Claims (17)

A photothermographic material containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions, and a binder on one surface of a support, and having the following general formula (AR) A photothermographic material comprising a compound represented by the formula:

In general formula (AR), A represents a quaternary salt structure of nitrogen or phosphorus as an adsorptive group to silver halide, and l represents an integer of 1 to 5. W represents a linking group, m represents 0 or 1, and n represents an integer of 1 to 5. B represents a reducing group.   2. The photothermographic material according to claim 1, wherein in the general formula (AR), the adsorptive group of A to silver halide has a quaternary salt structure of nitrogen.   3. The general formula (AR), wherein the adsorptive group to silver halide of A is a 5-membered or 6-membered nitrogen-containing aromatic heterocycle containing a quaternized nitrogen atom. The photothermographic material described in 1.   4. The photothermographic material according to claim 1, wherein n is 2 to 5 in the general formula (AR).   The reducing group of the general formula (AR) is a formyl group, an amino group, a triple bond group such as an acetylene group or a propargyl group, an alkyl mercapto group, or an aryl mercapto group. The photothermographic material according to Item. The reducing group of the general formula (AR) is any group selected from the groups represented by the following (B ₁ ) to (B ₃ ): 5. Photothermographic material:
(In the formula, in the groups represented by the following (B ₁ ) to (B ₃ ), R _b1 and R _b2 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. Represents.)

  The reducing group of the general formula (AR) is a group derived from any of reductones, phenols, naphthols, and phenylenediamines, according to any one of claims 1 to 4. Photothermographic material.   8. The photothermographic material according to claim 1, wherein a silver iodide content of the silver halide photographic emulsion is 40 mol% or more and 100 mol% or less.   9. The photothermographic material according to claim 1, wherein the silver halide photographic emulsion has a silver iodide content of 80 mol% or more and 100 mol% or less.   10. The photothermographic material according to claim 1, wherein the silver halide photographic emulsion contains tabular grains having an average aspect ratio of 2 or more.   11. The photothermographic material according to claim 10, wherein the average aspect ratio of the tabular grains is 5 or more and 50 or less.   12. The photothermographic material according to claim 10, wherein an average sphere equivalent diameter of the tabular grains is from 0.1 [mu] m to 10 [mu] m.   13. The photothermographic material according to claim 1, wherein the silver halide photographic emulsion is spectrally sensitized.   The photothermographic material according to claim 1, wherein the image forming layer has both sides of a support.   The photothermographic material according to claim 1, wherein the photothermographic material is in close contact with a fluorescent intensifying screen containing a phosphor having an emission wavelength of 350 nm or more and 420 nm or less and exposed to X-rays. Image forming method.   The image forming method according to claim 15, wherein the phosphor is a divalent Eu-activated phosphor.   The image forming method according to claim 15 or 16, wherein the phosphor is a divalent Eu-activated barium halide phosphor.

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