JP2006235396A - Heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high sensitivity, high image density and excellent image storage stability. <P>SOLUTION: The heat developable photosensitive material contains a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on a surface of a support, wherein the heat developable photosensitive material contains a compound represented by the formula (1): E<SP>1</SP>-Ch-E<SP>2</SP>wherein Ch represents S, Se or Te and E<SP>1</SP>and E<SP>2</SP>are each independently selected from the groups represented by formulae (2)-(5). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photothermographic material. In particular, the present invention relates to a photothermographic material having high sensitivity, high image density, and improved image storage stability.

  In recent years, in the medical field, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental protection and space saving. Therefore, the photosensitive heat for medical diagnosis and photographic technology that can be efficiently exposed by a laser image setter or a laser imager and can form a clear black image having high resolution and sharpness. There is a need for techniques relating to developed photographic materials. These photosensitive photothermographic materials can eliminate the use of solution processing chemicals and supply customers with a simpler heat development processing system that does not damage the environment.

  Although there is a similar requirement in the field of general image forming materials, medical images are required to have high image quality with excellent sharpness and graininess because they are required to be finely drawn, and are cooled from the viewpoint of ease of diagnosis. There is a feature that a black tone image is preferred. At present, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems. However, there is no satisfactory output system for medical images.

  On the other hand, thermal image forming systems using organic silver salts are described in many documents (for example, see Non-Patent Document 1, Patent Documents 1 and 2). In particular, a photothermographic material generally contains a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and a color toning agent that controls the color tone of silver if necessary. And an image forming layer dispersed in the matrix. 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. Therefore, a black silver image is formed in the exposure area. Fuji Medical Dry Imager FM-DPL was released as a medical image forming system using a photothermographic material.

On the other hand, an image forming system in which image information is digitized, stored, image processed as necessary, transmitted via a network, and laser output to a photothermographic material at a necessary place has become widespread. As the image forming material, a photothermographic material is most preferably used. As a laser light source, coherent light such as argon, helium-neon, helium-cadmium is used. Recently, the spread of semiconductor lasers is remarkable. The image information is subjected to scanning exposure with one or a plurality of laser beams. As such a system spreads, an increase in image production speed has been demanded. In order to increase the speed, it is necessary to increase the laser output, but there are problems that the apparatus becomes large and expensive, and that the laser life is shortened when the voltage is increased. Although high sensitivity of the photothermographic material has been demanded, there has been a limit in the past due to the problem of increased fog. Furthermore, since the photosensitive silver halide remains in the photothermographic material even after heat development, if the sensitivity is increased, the image is gradually blackened by exposure to room light after heat development (in the present application, “print-out fogging”). ”) Is aggravated. For this reason, studies have been made to reduce the amount of the photosensitive silver halide. However, it was difficult to reduce the weight while maintaining sensitivity and maximum density. As a chemical sensitization method for photosensitive silver halide grains, a sulfur sensitization method, a selenium sensitization method or a tellurium sensitization method is generally known. As chemical sensitizers for photothermographic materials, compounds described in paragraph No. 0030 of Patent Document 3 and tellurium compounds represented by the general formulas (II), (III), and (IV) described in Patent Document 4 are provided. It was known.
However, even with these, the sensitivity is still not sufficient, and further enhancement of sensitivity has been desired.
D. H. “Thermal Processed Silver Systems” (Imaging Processes and Materials), 8th edition, Sturge, V. Walth, by Klostervale, “Thermally Processed Silver Systems”. ), A. Shepp, Chapter 8, 279, 1989) US Pat. No. 3,152,904 US Pat. No. 3,457,075 JP-A-11-65021 JP-A-5-313284

  An object of the present invention is to solve the above-mentioned problems of the prior art. More specifically, the problem to be solved by the present invention is to provide a photothermographic material having high sensitivity, low fog, high maximum density, and small fog deterioration after heat development.

The object of the present invention has been achieved by the following photothermographic materials.
<1> A photothermographic material containing photosensitive silver halide, non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support, represented by the following general formula (1): A photothermographic material comprising the compound:
Formula (1) E ¹ -Ch-E ²
(In the formula (1), Ch represents a sulfur atom, a selenium atom, or a tellurium atom. E ¹ and E ² are independently from the groups represented by the following general formulas (2) to (5)). And each may be the same or different, provided that E ¹ and E ² are not simultaneously selected from the group represented by the formula (2).);

(In General Formula (2), Z represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, —OR ¹ or —NR ² R ³ , and R ^{1 to} R ³ represent an alkyl group, an alkenyl group, An alkynyl group, an aryl group, or a heterocyclic group, in formula (3), L represents a divalent linking group, EWG represents an electron withdrawing group, and in formula (4), A ¹ represents oxygen Represents an atom, a sulfur atom or —N (R ⁷ ) —, and R ^{4 to} R ⁷ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. ² represents an oxygen atom, a sulfur atom or —N (R ¹¹ ) —, R ⁸ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group or an acyl group, and R ^{9 to} R ^11. Is a hydrogen atom, an alkyl Represents a group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, X represents a substituent which can be substituted on the benzene ring, n represents an integer of 0 to 4. When n is 2 or more, X is Same or different.)
<2> The photothermographic material according to <1>, wherein the photosensitive silver halide is chemically sensitized with the compound represented by the general formula (1).
<3> The photothermographic material according to <1> or <2>, wherein at least one of E ¹ and E ² is a group selected from the general formula (4) or (5).
<4> The photothermographic material according to <3>, wherein at least one of E ¹ and E ² is a group selected from the general formula (5).
<5> The photothermographic material according to any one of <1> to <4>, wherein Ch is a selenium atom.
<6> The photothermographic material according to any one of <1> to <4>, wherein Ch is a tellurium atom.
<7> The photothermographic material according to any one of <1> to <6>, wherein the photosensitive silver halide is gold sensitized.
<8> The water-soluble thiocyanate is contained in an amount of 1 × 10 ⁻³ mol or more and 8 × 10 ⁻¹ mol or less per mol of silver halide, according to any one of <1> to <7> The photothermographic material according to the description.
<9> The photothermographic material according to any one of <1> to <8>, wherein the silver bromide content of the photosensitive silver halide is 70 mol% or more.
<10> The photothermographic material according to <9>, wherein the photosensitive silver halide has an average grain size of 0.01 μm to 0.2 μm.
<11> 50% or more of the total projected area of the photosensitive silver halide is a tabular grain having an aspect ratio of 2 or more, and the average grain size is 0.3 μm or more and 8.0 μm or less <1> to <1. 9. The photothermographic material according to any one of 9>.

According to the present invention, it is possible to provide a photothermographic material having high sensitivity, low fog, high maximum density, and little fog increase during image storage.

The present invention is described in detail below.
(Compound represented by the general formula (1))
The chalcogen compound represented by the general formula (1) used as a chemical sensitizer in the present invention will be described in detail.

Formula (1) E ¹ -Ch-E ²
In the formula (1), Ch represents a sulfur atom, a selenium atom or a tellurium atom. In the present invention, a selenium atom or a tellurium atom is preferable, and a selenium atom is more preferable.

In the general formula (1), E ¹ and E ² are selected from groups represented by the general formula (2) to the general formula (5). However, E ¹ and E ² are not both groups represented by the general formula (2).

In the general formula (2), Z represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, OR ¹ or NR ² R ³ , and R ^{1 to} R ³ represent an alkyl group, an alkenyl group, an alkynyl group, Represents an aryl group or a heterocyclic group. The alkyl group referred to here represents a linear, branched, or cyclic substituted or unsubstituted alkyl group. Preferably, it is a substituted or unsubstituted linear or branched alkyl group having 1 to 30 carbon atoms (for example, methyl group, ethyl group, isopropyl group, n-propyl group, n-butyl group, t-butyl group, 2-pentyl group). N-hexyl group, n-octyl group, t-octyl group, 2-ethylhexyl group, 1,5 dimethylhexyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, hydroxyethyl Group, hydroxypropyl group, 2,3-dihydroxypropyl group, carboxymethyl group, carboxyethyl group, sodium sulfoethyl group, diethylaminoethyl group, diethylaminopropyl group, butoxypropyl group, ethoxyethoxyethyl group, n-hexyloxypropyl group Etc.), a substituted or unsubstituted cyclic alkyl group having 3 to 18 carbon atoms (eg If cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, adamantyl group, a cyclododecyl group). Further, it is a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms (that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo [1,2,2 Heptan-2-yl, bicyclo [2,2,2] octane-3-yl), and a tricyclo structure having more ring structures. The alkenyl group represented by R ^{1 to} R ³ represents an alkenyl group having 2 to 16 carbon atoms (for example, an allyl group, a 2-butenyl group, a 3-pentenyl group, etc.), and represented by R ^{1 to} R ^3. The alkynyl group represents an alkynyl group having 2 to 10 carbon atoms (for example, propargyl group, 3-pentynyl group, etc.).

The aryl group represented by R ^{1 to} R ³ is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, such as phenyl, p-tolyl, naphthyl, m-chlorophenyl, o-hexadecanoylaminophenyl. It is. The heterocyclic group represented by R ^{1 to} R ³ is a 5- to 7-membered, substituted or unsubstituted, saturated or unsaturated hetero ring containing at least one of a nitrogen atom, an oxygen atom and a sulfur atom. It is a ring. These may be monocyclic or may form a condensed ring together with another aryl ring or hetero ring. The heterocyclic group is preferably a 5- to 6-membered one, for example, pyrrolyl group, pyrrolidinyl group, pyridyl group, piperidyl group, piperazinyl group, imidazolyl group, pyrazolyl group, pyrazinyl group, pyrimidinyl group, triazinyl group, triazolyl group, tetrazolyl group Group, quinolyl group, isoquinolyl group, indolyl group, indazolyl group, benzimidazolyl group, furyl group, pyranyl group, chromenyl group, thienyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, benzoxazolyl group, benzothiazolyl group, Examples thereof include a morpholino group and a morpholinyl group.

R ^{1 to} R ³ may have a substituent, and examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. , Heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, Thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy group (including its salts), oxalyl group, oxamoyl group, cyano group, formyl group, hydroxy group, alkoxy group (ethyleneoxy group or propyleneoxy group) Including groups containing repeating units), Reeloxy group, heterocyclic oxy group, acyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, carbamoyloxy group, sulfonyloxy group, silyloxy group, nitro group, amino group, (alkyl, aryl, or heterocyclic) amino Group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group , Ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, quaternized nitrogen atom Heterocyclic group (for example, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, alkylthio group, arylthio group, heterocyclic thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl Or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group (including salts thereof), sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfamoyl group (including salts thereof), A silyl group etc. are mentioned. Here, the salt means a salt with a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion.

  In the general formula (2), in the present invention, Z is preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and more preferably an alkyl group or an aryl group.

  In the general formula (3), the divalent linking group represented by L represents an alkylene group having 2 to 20 carbon atoms, an alkenylene group or an alkynylene group, and particularly a linear, branched or cyclic group having 2 to 10 carbon atoms. An alkylene group (for example, ethylene, propylene, cyclopentylene, cyclohexylene), an alkenylene group (for example, vinylene), and an alkynylene group (for example, propynylene) are represented. Preferred examples of L include those represented by general formula (L1) and general formula (L2).

In General Formula (L1) and General Formula (L2), G ¹ , G ² , G ³ , and G ⁴ are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 1 to 1 carbon atoms. Represents 10 heterocyclic groups, and G ¹ , G ² , and G ³ may be linked to form a ring. G ¹ , G ² , G ³ and G ⁴ are preferably a hydrogen atom, an alkyl group or an aryl group, and more preferably a hydrogen atom or an alkyl group.

  In the general formula (3), EWG represents an electron withdrawing group. The electron withdrawing group here is a substituent having a positive Hammett's substituent constant σp value, preferably a σp value of 0.2 or more, and an upper limit of 1.0 or less. Represents a group. Specific examples of the electron withdrawing group having a σp value of 0.2 or more include acyl group, formyl group, acyloxy group, acylthio group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, cyano group, nitro group, dialkylphospho Group, diarylphosphono group, dialkylphosphinyl group, diarylphosphinyl group, phosphoryl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfonyloxy group, acylthio group, sulfamoyl group, thiocyanate Group, thiocarbonyl group, imino group, imino group substituted with N atom, carboxy group (or salt thereof), alkyl group substituted with at least 2 halogen atoms, substituted with at least 2 halogen atoms An alkoxy group, at least An aryloxy group substituted with two or more halogen atoms, an acylamino group, an alkylamino group substituted with at least two halogen atoms, an alkylthio group substituted with at least two halogen atoms, or a σp value of 0 And aryl groups, heterocyclic groups, halogen atoms, azo groups, and selenocyanate groups substituted with two or more other electron-withdrawing groups. In the present invention, EWG is preferably an acyl group, formyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, cyano group, nitro group, dialkylphosphono group, diarylphosphono group, dialkylphosphinyl group, diarylphosphine group. Finyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, thiocarbonyl group, imino group, imino group substituted with N atom, phosphoryl group, carboxy group (or salt thereof), at least An alkyl group substituted with two or more halogen atoms, an aryl group substituted with another electron withdrawing group having a σp value of 0.2 or more, a heterocyclic group, or a halogen atom, more preferably an acyl group , Formyl group, carbamoyl group, alkoxy group Bonyl group, aryloxycarbonyl group, cyano group, nitro group, alkylsulfonyl group, arylsulfonyl group, carboxy group, alkyl group substituted with at least two halogen atoms, more preferably acyl group, formyl group, A cyano group, a nitro group, an alkylsulfonyl group, an arylsulfonyl group, or an alkyl group substituted with at least two halogen atoms.

In the general formula (4) R ⁴ to R ⁷ is a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, R ¹ ~ in the general formula (2) is an alkyl group referred to herein R ³ has the same meaning as the alkyl group represented by, and preferred ranges are also the same. Similarly, the alkenyl group, alkynyl group, aryl group, and heterocyclic group are the same as the alkenyl group, alkynyl group, aryl group, and heterocyclic group represented by R ^{1 to} R ^3, respectively, and the preferred ranges are also the same.

In the present invention, R ⁴ is preferably an alkyl group. R ⁵ and R ⁶ are preferably a hydrogen atom, an alkyl group or an aryl group, more preferably a hydrogen atom or an alkyl group, and most preferably one is a hydrogen atom and the other is a hydrogen atom or an alkyl group. R ⁷ is preferably a hydrogen atom, an alkyl group or an aryl group, more preferably a hydrogen atom or an alkyl group, and most preferably an alkyl group.

In the general formula (4), A ¹ represents an oxygen atom, a sulfur atom or NR ^{7. In} the present invention, A ¹ is preferably an oxygen atom or a sulfur atom, and most preferably an oxygen atom.

Next, general formula (5) will be described.
In general formula (5), the alkyl group represented by R ^{8 to} R ¹¹ has the same meaning as the alkyl group represented by R ^{1 to} R ³ in general formula (2), and the preferred range is also the same. Similarly, the alkenyl group, alkynyl group, aryl group, and heterocyclic group are the same as the alkenyl group, alkynyl group, aryl group, and heterocyclic group represented by R ^{1 to} R ^3, respectively, and the preferred ranges are also the same. Examples of the acyl group represented by R ⁸ include an acetyl group, a formyl group, a benzoyl group, a pivaloyl group, a caproyl group, and an n-nonanoyl group.

In the general formula (5), X represents a substituent, and examples thereof include the same substituents that R ^{1 to} R ³ may have in the general formula (2).

  In the present invention, X is preferably a halogen atom, alkyl group, aryl group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N- Carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy group (including its salt), cyano group, formyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, Acyloxy group, nitro group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, alkylthio group, arylthio group, heterocyclic thio group, (alkyl or aryl) Sulfo Group, (alkyl or aryl) sulfinyl group, sulfo group (including salts thereof), sulfamoyl group, etc., more preferably halogen atom, alkyl group, aryl group, heterocyclic group, carboxy group (and salts thereof). Including), hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, acyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, ureido group, thioureido group, alkylthio group, arylthio group , A heterocyclic thio group, a sulfo group (including a salt thereof) and the like, more preferably an alkyl group, an aryl group, a carboxy group (including a salt thereof), a hydroxy group, an alkoxy group, an aryloxy group, (alkyl , Aryl, or heterocyclic) amino group, ureido group, alkylthio , An arylthio group, (including and salts thereof) a sulfo group and the like.

  In general formula (5), n represents an integer of 0 to 4. In the present invention, n preferably represents 0 to 2, more preferably 0 or 1.

In the general formula (5), A ² represents an oxygen atom, a sulfur atom or NR ¹¹ , but in the present invention, it preferably represents an oxygen atom or a sulfur atom.

In the present invention, among the compounds represented by the general formula (1), preferred are those in which at least one of E ¹ and E ² is selected from the group represented by the general formula (4) or the general formula (5). It is. More preferably, Ch is a selenium atom or a tellurium atom, one of E ¹ and E ² is selected from the group represented by the general formula (4), and the other is the general formula (2), the general formula (4), When selected from the group represented by the general formula (5), or one selected from the group represented by the formula (5) and the other from the group represented by the general formula (2) or the general formula (5) This is the case. More preferably, Ch is a selenium atom, and one of E ¹ and E ² is selected from the group represented by the general formula (4), and the other is the general formula (2), the general formula (4), the general formula ( When selected from the group represented by 5), or one is selected from the group represented by the general formula (5), and the other is selected from the group represented by the general formula (2) or the general formula (5). Is the case.

  Next, specific examples of the compound represented by the general formula (1) are shown below. However, the present invention is not limited to these. In addition, the three-dimensional structure of a compound in which a plurality of stereoisomers can exist is not limited. In the following exemplary compounds, Ac represents an acetyl group.

  The compound represented by the general formula (1) of the present invention can be synthesized by various known methods. Since an optimum synthesis method is selected depending on individual compounds, a general synthesis method cannot be mentioned. Among them, a useful synthesis route will be described.

<< Synthesis of Exemplified Compound 1 >>
Exemplary Compound 1 was synthesized according to Scheme 1.

  3.2 g of benzyl chloromethyl ether was dissolved in 20 mL of acetone, a solution of 2 g of selenourea in 80 mL of acetone was added, and the mixture was stirred at room temperature for 1 hour. The precipitated solid was collected by filtration to obtain 4.6 g of synthetic intermediate 1. After adding 40 mL of water and 0.2 g of benzyltriethylammonium chloride to 2 g of the synthetic intermediate 12, 4 mL of 5M NaOH aqueous solution was added. A solution of 1.2 g of p-methoxybenzoyl chloride in 10 mL of ethyl acetate was added, and the mixture was stirred at room temperature for 1 hour. Ethyl acetate (80 mL) and dilute hydrochloric acid (100 mL) were added to separate the organic layer, which was washed with water and concentrated under reduced pressure. 1.8g of exemplary compound 1 was obtained by refine | purifying the obtained residue with column chromatography.

<< Synthesis of Exemplified Compound 2 >>
Exemplified Compound 2 could be obtained by carrying out substantially the same procedure in the synthesis of Exemplified Compound 1 except that benzyl chloromethyl sulfide was used instead of benzyl chloromethyl ether.

<< Synthesis of Exemplified Compound 3 >>
To a solution of 1,2,3,4,6-pentaacetyl-β-D-glucopyranose (13 g) in methylene chloride (60 mL) was added a hydrogen bromide 30% acetic acid solution (25 g). After stirring overnight at room temperature, 100 mL of ice water and 100 mL of methylene chloride were added for liquid separation. The organic layer was washed with 30 mL of a saturated aqueous sodium bicarbonate solution and 30 mL of a saturated aqueous sodium chloride solution, dried over sodium sulfate, and concentrated under reduced pressure. Ethanol 60mL was added to the obtained oily substance, and the precipitated crystals were collected by filtration to obtain 11 g of 1-bromo-2,3,4,6-pentaacetyl-β-D-glucopyranose. 10.5 g of 1-bromo-2,3,4,6-pentaacetyl-β-D-glucopyranose and 3.1 g of selenourea were added to 100 mL of acetone, followed by heating under reflux for 1 hour. 30 mL of water was added to 3.1 g of crystals obtained by cooling the reaction solution with ice and filtering, and then 5 mL of 1.6 g of potassium carbonate and then 18 mL of THF were added. A solution of 1 g of p-methoxybenzoyl chloride in 5 mL of ethyl acetate was added dropwise and stirred at room temperature for 1 hour, and then 100 mL of ethyl acetate and 100 mL of dilute hydrochloric acid were added to separate the organic layer, which was washed with water and concentrated under reduced pressure. 2g of exemplary compound 3 was obtained by refine | purifying the obtained residue with column chromatography.

The amount of the compound represented by the general formula (1) of the present invention may vary widely depending on the case, but it is 1 × 10 ^{−7 to} 5 × 10 ⁻³ mol, preferably 5 × 10, per 1 mol of silver halide. ^{−7 to} 5 × 10 ⁻⁴ mol.

  The compound represented by the general formula (1) of the present invention is water or alcohols (such as methanol and ethanol), ketones (such as acetone), amides (such as dimethylformamide), glycols (such as methylpropylene glycol). , And esters (such as ethyl acetate) may be added as a solvent.

  Although the compound represented by the general formula (1) of the present invention can be added at any stage during the production of the emulsion, it is preferably added after the formation of the silver halide grains until the end of the chemical sensitization step. .

(Description of organic silver salt)
1) Composition The organic silver salt that can be used in the present invention is relatively stable to light, but is heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide and a reducing agent. In this case, the silver salt functions as a silver ion supplier to form a silver image. The organic silver salt may be any organic substance that can supply silver ions that can be reduced by a reducing agent. 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. Preferred examples of the fatty acid silver salt include silver lignocerate, silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver erucate and the like. Including a mixture of In the present invention, among these fatty acid silvers, the silver behenate content is preferably 50 mol% to 100 mol%, more preferably 85 mol% to 100 mol%, still more preferably 95 mol% to 100 mol%. The following fatty acid silver is preferably used. Furthermore, it is preferable to use fatty acid silver having a silver erucate content of 2 mol% or less, more preferably 1 mol% or less, and still more preferably 0.1 mol% or less.

  Moreover, it is preferable that silver stearate content rate is 1 mol% or less. By making the stearic acid content 1 mol% or less, a silver salt of an organic acid having a low Dmin, high sensitivity and excellent image storage stability can be obtained. As said stearic acid content rate, 0.5 mol% or less is preferable and it is especially preferable not to contain substantially.

  Furthermore, when silver arachidate is included as the silver salt of the organic acid, the silver arachidate content is 6 mol% or less to obtain a low Dmin and an organic acid silver salt excellent in image storability. It is preferable at a point and it is still more preferable that it is 3 mol% or less.

2) Shape The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a flake shape.
In the present invention, scaly organic silver salts are preferred. In addition, short needle-shaped, rectangular parallelepiped, cubic or potato-shaped irregular particles having a major axis / uniaxial length ratio of less than 5 are also preferably used. These organic silver particles have a feature that the fog at the time of heat development is less than that of long needle-like particles in which the ratio of the length of the major axis to the uniaxial axis is 5 or more. In particular, particles having a major axis / uniaxial ratio of 3 or less are preferable because the mechanical stability of the coating film is improved. In the present specification, the scaly organic silver salt is defined as follows. The organic acid silver salt was observed with an electron microscope, and the shape of the organic acid silver salt particle was approximated to a rectangular parallelepiped. Then, calculation is performed using the shorter numerical values a and b, and x is obtained as follows.
x = b / a

  In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, 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 c / b is preferably 1 or more and 9 or less, more preferably 1 or more and 6 or less, still more preferably 1 or more and 4 or less, and most preferably 1 or more and 3 or less.

By setting the sphere equivalent diameter to 0.05 μm or more and 1 μm or less, aggregation is hardly caused in the photothermographic material, and image storability is improved. The sphere equivalent diameter is preferably 0.1 μm or more and 1 μm or less. In the present invention, the method for measuring the equivalent sphere diameter is obtained by directly photographing a sample using an electron microscope and then image-processing the negative.
In the flake shaped particles, the spherical equivalent diameter / a of the particles is defined as the aspect ratio. The aspect ratio of the flake shaped particles is preferably 1.1 or more and 30 or less, and preferably 1.1 or more and 15 or less, from the viewpoint of preventing aggregation in the photothermographic material and improving the image storage stability. More preferred.

  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. It is as follows. 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 for obtaining 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.

3) Preparation Known methods and the like can be applied to the production and dispersion method of organic acid silver used in the present invention. For example, the above-mentioned JP-A-10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, JP-A-2001-163889, 2001-163890, 2001-163825, 2001-33907, 2001-188313, 2001-83651, 2002-6442, 2002-49117, 2002-31870, 2002-107868 You can refer to the issue.

  In addition, when the photosensitive silver salt is allowed to coexist at the time of dispersion of the organic silver salt, the fog rises and the sensitivity is remarkably lowered. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. In the present invention, the amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is preferably 1 mol% or less, more preferably 0.1 mol% or less with respect to 1 mol of the organic acid silver salt in the liquid. Further, it is more preferable that no positive photosensitive silver salt is added.

  In the present invention, a photothermographic material can be produced by mixing an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion, but the mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose. However, the ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 mol% to 30 mol%, more preferably 2 mol% to 20 mol%, and particularly preferably 3 mol% to 15 mol%. 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.

4) Addition amount Although the organic silver salt in the present invention can be used in a desired amount, the total coating silver amount including silver halide is preferably 0.1 g / m ² or more and 5.0 g / m ² or less, more preferably. It is 0.3 g / m ² or more and 3.0 g / m ² or less, more preferably 0.5 g / m ² or more and 2.0 g / m ² or less. In particular, in order to improve image storability, the total coated silver amount is preferably 1.8 g / m ² or less, more preferably 1.6 g / m ² or less. If the preferred reducing agent in the present invention is used, a sufficient image density can be obtained even with such a low silver amount.

(Description of reducing agent)
The photothermographic material of the present invention preferably contains a heat developer which is a reducing agent for the organic silver salt. The reducing agent for the organic silver salt may be any substance (preferably an organic substance) that reduces silver ions to metallic silver. Examples of such reducing agents are described in JP-A No. 11-65021, paragraphs 0043 to 0045, and European Patent Publication No. 0803764A1, page 7, line 34 to page 18, line 12.
In the present invention, the reducing agent is preferably a so-called hindered phenol-based reducing agent or bisphenol-based reducing agent having a substituent at the ortho position of the phenolic hydroxyl group, and more preferably a compound represented by the following general 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 ′ can each independently be substituted with a hydrogen atom or a benzene ring. represents a substituent .L is, -S- group or a -CHR ¹³ - .X ¹ and X ¹ .R ¹³ represents a group represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms' each independently represent a hydrogen atom Or represents a substitutable group on the benzene ring.)

The general formula (R) will be described in detail.
When referred to as an alkyl group in the following, a cycloalkyl group is also included in this unless otherwise specified.
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. The substituent of the alkyl group is not particularly limited, but preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group, Examples thereof include an acyl group, a carbamoyl group, an ester group, a ureido group, a urethane 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 substituent that can be substituted on a benzene ring, and X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on 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 for R ¹³ are methyl group, ethyl group, propyl group, butyl group, heptyl group, undecyl group, isopropyl group, 1-ethylpentyl group, 2,4,4-trimethylpentyl group, cyclohexyl group. Group, 2,4-dimethyl-3-cyclohexenyl group, 3,5-dimethyl-3-cyclohexenyl group and the like. 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 primary, secondary or tertiary alkyl groups having 1 to 15 carbon atoms, specifically methyl, isopropyl, t-butyl, t -Amyl group, t-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like can be mentioned. R ¹¹ and R ¹¹ ′ are more preferably an alkyl group having 1 to 4 carbon atoms, and among them, a methyl group, a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a methyl group and a t-butyl group are preferable. Groups are most preferred.

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, and particularly preferred are methyl group and ethyl 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. As the alkyl group, a cyclic alkyl group is also preferably used in addition to a chain alkyl group. Moreover, what has a C = C bond in these alkyl groups can also be used preferably. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, 2,4,4-trimethylpentyl group, cyclohexyl group, 2,4-dimethyl-3-cyclohexenyl group, 3,5-dimethyl-3- A cyclohexenyl group and the like are preferable. R ¹³ is particularly preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4-dimethyl-3-cyclohexenyl group.

When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are methyl groups, R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group, propyl group). Group, isopropyl group, 2,4-dimethyl-3-cyclohexenyl group and the like).
When R ¹¹ and R ¹¹ ′ are tertiary alkyl groups and R ¹² and R ¹² ′ are alkyl groups other than methyl groups, R ¹³ is preferably a hydrogen atom.
When R ¹¹ and R ¹¹ ′ are not a tertiary alkyl group, R ¹³ is preferably a hydrogen atom or a secondary alkyl group, and particularly preferably a secondary alkyl group. Preferred groups as the secondary alkyl group for R ¹³ are isopropyl, 2,4-dimethyl-3-cyclohexenyl, and cyclohexyl.
The reducing agent has different heat developability, developed silver color tone and the like depending on the combination of R ¹¹ , R ¹¹ ′, R ¹² , R ¹² ′ and R ¹³ . Since these can be adjusted by combining two or more kinds of reducing agents, it is preferable to use two or more kinds in combination depending on the purpose.

  Although the specific example of the reducing agent in this invention including the compound represented by general formula (R) below is shown, this invention is not limited to these.

Examples of preferable reducing agents in the present invention other than the above are the compounds described in JP-A Nos. 2001-188314, 2001-209145, 2001-350235, 2002-156727, and EP1278101A2.
In the present invention, the addition amount of the reducing agent is preferably 0.1 g / m ² or more and 3.0 g / m ² or less, more preferably 0.2 g / m ² or more and 2.0 g / m ² or less, and still more preferably. Is 0.3 g / m ² or more and 1.0 g / m ² or less. 5 mol% or more and 50 mol% or less is preferably contained with respect to 1 mol of silver on the surface having the image forming layer, more preferably 8 mol% or more and 30 mol% or less, and 10 mol% or more and 20 mol% or less. More preferably, it is contained. The reducing agent is preferably contained in the image forming layer.

The reducing agent 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 photothermographic 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 thereof 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.

Further, as a solid fine particle dispersion method, a reducing agent powder is dispersed in an appropriate 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. A method 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 reducing agent, in which 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 are added. Is preferred. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

(Description of 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 Nos. 10-62895 and 11-15116, A hydrazine-based compound represented by the general formula (D) of JP-A No. 2002-156727 or the general formula (1) described in JP-A No. 2002-278017, and described in the specification of JP-A No. 2001-264929 Phenol-based or naphthol-based compounds represented by the general formula (2) are preferably used. Moreover, the phenol type compound described in Unexamined-Japanese-Patent No. 2002-311533 and Unexamined-Japanese-Patent No. 2002-341484 is also preferable. In particular, naphthol compounds described in JP-A No. 2003-66558 are preferable. These development accelerators are used in the range of 0.1 mol% or more and 20 mol% or less, preferably 0.5 mol% or more and 10 mol% or less, more preferably 1 mol% or more with respect to the reducing agent. The range is 5 mol% or less. 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 and a low-boiling auxiliary solvent that are solid at room temperature, 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 described in JP-A Nos. 2002-156727 and 2002-278017 and naphthol compounds described in JP-A No. 2003-66558 are used. Is more preferable.

Particularly preferred development accelerators in the 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 Q ₂ is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, Examples include dodecyloxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ₂ is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples thereof include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q ₂ is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, 3- Examples include dodecyloxypropylsulfonyl, 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 listed as an example of the substituent of the 5-membered 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 a nitrogen atom.

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. R ₂ 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.), aryl An oxy 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, 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, preferred specific examples of the development accelerator in the present invention will be given. The present invention is not limited to these.

(Description of hydrogen bonding compounds)
When the reducing agent in the present invention has an aromatic hydroxyl group (—OH) or amino group (—NHR, R is a hydrogen atom or an alkyl group), particularly in the case of the aforementioned bisphenols, these groups and hydrogen bonds It is preferable to use together a non-reducing compound having a group capable of forming.
Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Can be mentioned. 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, a particularly preferred hydrogen bonding compound is a compound represented by the following general 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 as a substituent is 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 a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group, a 4-t-octylphenyl group, a 4-anisidyl group, and a 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 European Patent No. 1096310, JP-A No. 2002-156727, and JP-A No. 2002-318431 in addition to the above.
The compound of the general formula (D) in the present invention can be used in a photothermographic material by being incorporated in a coating solution in the form of a solution, an emulsified dispersion, or a solid dispersion fine particle dispersion in the same manner as the reducing agent. It is preferably used as a solid dispersion. These compounds form a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state. It can be isolated in the state.
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 compound of the general formula (D) in the present invention are mixed in 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 compound of the general formula (D) in the present invention is preferably used in the range of 1 mol% to 200 mol%, more preferably in the range of 10 mol% to 150 mol%, based on the reducing agent. More preferably, it is the range of 20 mol% or more and 100 mol%.

(Description of silver halide)
1) Halogen composition The photosensitive silver halide used in the present invention is not particularly limited as a halogen composition, and is silver chloride, silver chlorobromide, silver bromide, silver iodobromide, silver iodochlorobromide, silver iodide. Can be used. Of these, silver bromide, silver iodobromide and silver iodide are 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 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 technique for localizing silver bromide or silver iodide on the surface of silver chloride, silver bromide or silver chlorobromide grains can also be preferably used.

2) Grain size There are two preferred regions for the grain size of the photosensitive silver halide in the present invention.
One region is a fine particle region, preferably 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less, and further preferably 0.02 μm or more and 0.12 μm or less. The grain size here means the diameter when converted into a circular image having the same area as the projected area of silver halide grains (in the case of tabular grains, the projected area of the main plane).
Another region is tabular grains having an average aspect ratio of 2 or more, more preferably tabular grains having an average aspect ratio of 5 or more, and an average sphere equivalent diameter is preferably 0.3 μm to 8 μm. More preferably, it is 0.5 μm to 5 μm. The average equivalent sphere diameter in the present invention refers to the diameter when converted to a sphere having the same volume as the volume of the tabular silver halide grains.
The average thickness of the tabular silver halide in the present invention is preferably 0.3 μm or less, more preferably 0.2 μm or less, and still more preferably 0.1 μm or less.

3) Grain Forming Methods Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. In particular, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound into gelatin or another polymer solution, and then mixed with an organic silver salt. Use the method. Further, the method described in paragraph Nos. 0217 to 0224 of JP-A No. 11-119374, and the methods described in JP-A Nos. 11-352627 and 2000-347335 are also preferable.
Regarding the method for forming tabular grains, the methods described in JP-A-59-119350 and 59-119344 are preferably used.

4) Grain shape Examples of the shape of silver halide grains include cubes, octahedrons, tabular grains, spherical grains, rod-like grains, and potato grains. In the present invention, cubic grains are particularly preferred. Grains with rounded corners of silver halide grains can also be preferably used. The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the ratio of the {100} plane having high spectral sensitization efficiency when the spectral sensitizing dye is adsorbed is high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more. The ratio of the Miller index {100} plane is determined by T.T. Tani; Imaging Sci. 29, 165 (1985).

The silver halide grains in the present invention may be tabular grains.
The tabular grains preferably have an epitaxial portion.
The terms “epitaxy” and “epitaxial” are used in the art-recognized meaning to point out that the silver salt is a crystalline form with an orientation controlled by the host tabular grains. The
In order to create a sensitized site on the tabular host grain, a silver salt deposited by epitaxial growth can be used. By controlling the adhesion site by epitaxial growth, selective local sensitization of tabular host grains can be performed. Thus, sensitization sites can be provided at one or more regular sites. “Regular” means that the sensitized sites have a predictable and ordered relationship, preferably with each other, with respect to the main crystal planes of the tabular grains. By controlling the epitaxial adhesion with respect to the main crystal plane of the tabular grains, it is possible to control the number of sensitized sites and the spacing in the lateral direction.

  In the present invention, the epitaxial junction can be formed on the apex, main surface or edge of the tabular grain, but is preferably the apex. The number of epitaxial junctions is at least 1, preferably 2 or more, more preferably 4 or more in tabular grains.

In particular, it is preferable to control silver salt epitaxy and substantially eliminate epitaxial adhesion in at least a part of the main crystal plane of the tabular host grain. In tabular host grains, the epitaxial deposition of silver salt tends to occur at least one of the grain edges and corners.
When the epitaxial deposition is limited to selected portions of the tabular grains, the sensitivity is improved as compared with the case where the silver salt is randomly deposited on the main surface of the tabular grains by epitaxial growth.
The silver salt is adhered to the selected portion within a limited range so that the silver salt is not substantially epitaxially deposited on at least a part of the main crystal plane. The deposition range can be varied over a wide range without departing from the invention. In general, as the amount of epitaxial coating on the main crystal plane decreases, the increase in sensitivity increases. The silver salt deposited by epitaxial growth is preferably less than half of the area of the main crystal plane of the tabular grains, preferably less than 25%. When silver salt is deposited by epitaxial growth at the corners of the tabular silver halide grains, it is preferable to limit the area to less than 10%, more preferably less than 5%, of the area of the main crystal plane of the tabular grains. In certain embodiments, it has been observed that epitaxial deposition begins on the edge surfaces of tabular grains. Therefore, depending on conditions, epitaxy is limited to the selected edge portion, and epitaxy on the main crystal plane is effectively eliminated.

  When particles with latent image centers are fully developed, the location and number of latent image centers cannot be determined. However, if the development is stopped before the development range is expanded from the immediate vicinity of the latent image center and the partially developed particles are enlarged and observed, the partial development site can be clearly seen. These portions generally correspond to the latent image center, and such latent image center generally corresponds to the sensitized portion.

  The silver salt deposited by epitaxy can be selected from any silver salt that is conventionally known to be epitaxially grown on silver halide grains and to be effective in photography. In particular, the silver salt is preferably selected from those conventionally known to be effective for forming a shell of a core-shell silver halide emulsion. In addition to all known photographically useful silver halides, other silver salts known to be able to precipitate as silver salts on silver halide grains, such as silver cyanide, silver carbonate, ferricyanide Silver, silver arsenate or silver arsenite, and silver chromate. A mixture thereof may also be used. Among these, silver chloride, silver bromide, silver thiocyanate and a mixture thereof are preferable, and at least silver bromide is particularly preferable.

5) Heavy Metal The photosensitive silver halide grain in the invention may contain a metal or metal complex of Group 6 to Group 13 of the Periodic Table (showing Groups 1 to 18). More preferably, it can contain a metal or metal complex of Group 6 to Group 10 of the Periodic Table. As the central metal of the group 6 to group 10 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.

  The hexacyano metal complex is present in the form of ions in aqueous solution, so the counter cation is not important, but it is easy to mix with water and is suitable for precipitation of silver halide emulsions. Sodium ion, potassium ion, rubidium It is preferable to use alkali metal ions such as ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ions, tetraethylammonium ions, tetrapropylammonium ions, tetra (n-butyl) ammonium ions).

  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 silver nitrate aqueous 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.

  The addition of the hexacyano metal complex may be started after adding 96% by mass of the total amount of silver nitrate to be added to form grains, more preferably starting after adding 98% by mass, The addition of 99% by mass is particularly preferable.

  When these hexacyanometal complexes are added after the addition of the aqueous silver nitrate solution just before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grains, and most of them form slightly soluble salts with silver ions on the grain surface. To do. Since this silver salt of hexacyanoiron (II) is a less soluble salt than AgI, it is possible to prevent re-dissolution by fine particles and to produce silver halide fine particles having a small particle size. .

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.

6) Gelatin As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. It is necessary to maintain a good dispersion state of the photosensitive silver halide emulsion in the coating solution containing an organic silver salt, and gelatin having a molecular weight of 10,000 to 1,000,000 is preferably used. It is also preferable to phthalate the gelatin substituent. These gelatins may be used at the time of grain formation or at the time of dispersion after desalting, but are preferably used at the time of grain formation.

7) Sensitizing Dye Sensitizing dyes applicable to the present invention are those that can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and are suitable for the spectral characteristics of the exposure light source. Sensitizing dyes with sensitivity can be advantageously selected. 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. In the present invention, the time when the sensitizing dye is added to the silver halide emulsion is preferably the time from the desalting step to the coating, and more preferably the time from desalting to the end of chemical ripening.
The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with the sensitivity and fogging performance, but is preferably 10 ⁻⁶ to 1 mol, more preferably 1 mol per mol of silver halide in the image forming 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.

8) Chemical sensitization The photosensitive silver halide grain in the invention may be chemically sensitized by a gold sensitization method in combination with the chalcogen sensitization. As the gold sensitizer, the gold valence is preferably +1 or +3, and the gold sensitizer is preferably a commonly used gold compound. Typical examples are chloroauric acid, bromoauric acid, potassium chloroaurate, potassium bromoaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate, pyridyltrichlorogold. Etc. are preferable. Further, gold sensitizers described in US Pat. No. 5,858,637 and JP-A No. 2002-278016 are also preferably used.

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 sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, etc., but from 10 ⁻⁸ mol to 10 ⁻² mol per mol of silver halide, Preferably, about 10 ⁻⁷ mol to 10 ⁻³ mol is used.
The amount of the gold sensitizer added varies depending on various conditions, but as a guideline, it is 10 ⁻⁷ mol or more and 10 ⁻³ mol or less, more preferably 10 ⁻⁶ mol or more and 5 × 10 ⁻⁴ mol or less per mol of silver halide. It is.
The conditions for chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is about 40 ° C to 95 ° C.

In addition to the chemical sensitizer of the present invention, sulfur, selenium and tellurium sensitizers arbitrarily selected from known labile sulfur compounds, labile selenium compounds and labile tellurium compounds can be used in combination.
In the chemical sensitization of the present invention, it is preferable to use a water-soluble thiocyanate (for example, potassium thiocyanate, sodium thiocyanate, ammonium thiocyanate, etc.). The amount used can be arbitrarily selected, but it is 1 × 10 ⁻⁴ mol or more, further 1 × 10 ⁻³ mol or more, preferably 2 × 10 ⁻³ mol or more, per mol of silver halide. It is preferably 8 × 10 ⁻¹ mol or less, more preferably 3 × 10 ⁻³ mol or more and 2 × 10 ⁻¹ mol or less, particularly preferably 5 × 10 ⁻³ mol or more and 1 × 10 ⁻¹ mol or less.
The photothermographic material of the invention particularly preferably contains a water-soluble thiocyanate in an amount of 1 × 10 ⁻³ mol or more and 8 × 10 ⁻¹ mol or less per mol of silver halide.
A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method described in European Patent Publication No. 293,917.

  A reducing agent is preferably used for the photosensitive silver halide grains in the present invention. As specific compounds for the reduction sensitization, ascorbic acid and aminoiminomethanesulfinic acid are preferable, and in addition, it is preferable to use stannous chloride, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, and the like. 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 preferable by ripening while maintaining the pH of the emulsion at 7 or more or pAg at 8.3 or less, and reduction sensitization is achieved by introducing a single addition portion of silver ions during grain formation. It is also preferable to do.

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 1 electron or more. 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 formed by one-electron oxidation contained in the silver halide photographic light-sensitive material of the present invention is a compound selected from the following types 1 and 2 as the compound capable of emitting one electron or more. It is.
(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) (JP-A-2003-114487) 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), and 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). In the general formula (2)), the general formula (8) (Synonymous with general formula (1) described in JP-A-2004-239943) or chemical reaction formula (1) (synonymous with chemical reaction formula (1) described in JP-A-2004-245929) Among these compounds, compounds represented by the general formula (9) (synonymous with the general formula (3) described in JP-A No. 2004-245929) can be given. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the general formulas (1) and (2), 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- or 6-membered aromatic ring (including an aromatic heterocycle) or a hexahydro form together with carbon atom (C) and RED _1. To express. R ₂ , R ₃ and R ₄ represent a hydrogen atom or a substituent. Lv ₁ and Lv ₂ represent a leaving group. ED represents an electron donating group.

In the general formulas (3), (4) and (5), Z ₁ represents an atomic group capable of forming a 6-membered ring together with the nitrogen atom and the two carbon atoms of the benzene ring. _{R 5, R 6, R 7} , R 9, R 10, R 11, R 13, R 14, R 15, R 16, R 17, R 18, R 19 represents a hydrogen atom or a substituent. R ₂₀ represents a hydrogen atom or a substituent. When R ₂₀ represents a group other than an aryl group, R ₁₆ and R ₁₇ are bonded to each other to form an aromatic ring or an aromatic heterocycle. R ₈ and R ₁₂ represent a substituent that can be substituted on the benzene ring, m1 represents an integer of 0 to 3, and m2 represents an integer of 0 to 4. Lv ₃ , Lv ₄ and Lv ₅ represent a leaving group.

In general formulas (6) and (7), RED ₃ and RED ₄ represent a reducing group. R _{21 to} R ₃₀ represent a hydrogen atom or a substituent. Z ₂ represents —CR ₁₁₁ R ₁₁₂ —, —NR ₁₁₃ —, or —O—. R ₁₁₁ and R ₁₁₂ each independently represents a hydrogen atom or a substituent. _R113 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

In the general formula (8), RED ₅ is a reducing group and represents an arylamino group or a heterocyclic amino group. R ₃₁ represents a hydrogen atom or a substituent. X 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. Lv ₆ is a leaving group and represents a carboxy group or a salt thereof or a hydrogen atom.

The compound represented by the general formula (9) is a compound that undergoes a bond formation reaction represented by the chemical reaction formula (1) by further oxidation after two-electron oxidation accompanied by decarboxylation. In the chemical reaction formula (1), R ₃₂ and R ₃₃ represent a hydrogen atom or a substituent. Z ₃ represents a group which forms a 5-membered or 6-membered heterocycle with C═C. Z ₄ 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. In the general formula (9), R ₃₂ , R ₃₃ and Z ₃ have the same meaning as in the chemical reaction formula (1). Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C.

Next, the type 2 compound will be described.
As a compound in which a one-electron oxidant produced by one-electron oxidation with a type 2 compound can further emit one or more electrons with a subsequent bond formation reaction, a compound represented by the general formula (10) A compound capable of causing a 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 JP-A-2004-245929). And a compound represented by the general formula (11) (synonymous with the general formula (2) described in JP-A No. 2004-245929). The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the general formula (10), RED ₆ represents a reducing group that is one-electron oxidized. Y reacts with a one-electron oxidant formed by one-electron oxidation of RED ₆ to form a new bond, a carbon-carbon double bond site, a carbon-carbon triple bond site, an aromatic group site, or Reactive group containing a non-aromatic heterocyclic moiety of a benzo-fused ring. Q represents a linking group linking RED ₆ and Y.

The compound represented by the general formula (11) is a compound that causes a bond formation reaction represented by the chemical reaction formula (1) by being oxidized. In the chemical reaction formula (1), R ₃₂ and R ₃₃ represent a hydrogen atom or a substituent. Z ₃ represents a group which forms a 5-membered or 6-membered heterocycle with C═C. Z ₄ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C. M represents a radical, a radical cation, or a cation. In the general formula (11), R ₃₂ , R ₃₃ , Z ₃ and Z ₄ have the same meanings as those in the chemical reaction formula (1).

  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 are 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 heterocyclic 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 (trialkylphosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group, etc.). Can be mentioned. More preferably, a quaternary salt structure of nitrogen is used, and more preferably a 5-membered or 6-membered nitrogen-containing aromatic heterocyclic group containing a quaternized nitrogen atom is 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 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, 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 compounds of type 1 and type 2 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 raised or lowered 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 image forming 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 image forming layer containing, and diffused during coating. The addition timing of these compounds is preferably 1 × 10 ⁻⁹ mol to 5 × 10 ⁻¹ mol, more preferably 1 × 10 ⁻⁸ mol, per mol of silver halide, regardless of before and after the sensitizing dye. It is contained in a silver halide emulsion layer (image forming layer) at a ratio of ˜5 × 10 ⁻² mol.

10) Adsorbing redox compound having an adsorbing group and a reducing group In the present invention, it is preferable to contain an adsorbing redox compound having an adsorbing group and a reducing group for silver halide in the molecule. The adsorptive redox compound is preferably a compound represented by the following formula (I).

Formula (I) A- (W) n-B
In formula (I), A represents a group that can be adsorbed to silver halide (hereinafter referred to as an adsorbing group), W represents a divalent linking group, n represents 0 or 1, and B represents a reducing group. To express.

  In the formula (I), the adsorption group represented by A is a group that directly adsorbs to silver halide, or a group that promotes adsorption to silver halide, and specifically, a mercapto group (or a salt thereof). , A thione group (—C (═S) —), a heterocyclic group, a sulfide group, a disulfide group, a cationic group, or an ethynyl group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom, and a tellurium atom Etc.

The mercapto group (or salt thereof) as the adsorptive group means the mercapto group (or salt thereof) itself, and more preferably a heterocyclic group or aryl group substituted with at least one mercapto group (or salt thereof) or Represents an alkyl group. Here, the heterocyclic group is at least a 5- to 7-membered monocyclic or condensed aromatic or non-aromatic heterocyclic group such as an imidazole ring group, a thiazole ring group, an oxazole ring group, or a benzimidazole ring. Group, benzothiazole ring group, benzoxazole ring group, triazole ring group, thiadiazole ring group, oxadiazole ring group, tetrazole ring group, purine ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, pyrimidine ring group, And triazine ring group. Moreover, the heterocyclic group containing the quaternized nitrogen atom may be sufficient, and in this case, the substituted mercapto group may dissociate and it may become a meso ion. When the mercapto group forms a salt, the counter ion includes a cation such as alkali metal, alkaline earth metal, heavy metal (Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ag ⁺ , Zn ^2+, etc.), ammonium ion Examples thereof include a heterocyclic group containing a quaternized nitrogen atom, a phosphonium ion, and the like.
Further, the mercapto group as the adsorptive group may be tautomerized into a thione group.
The thione group as an adsorptive group includes a chain or cyclic thioamide group, thioureido group, thiourethane group, or dithiocarbamate group.
A heterocyclic group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom and a tellurium atom as the adsorptive group is a -NH- group capable of forming imino silver (> NAg) as a partial structure of the heterocyclic ring. A nitrogen-containing heterocyclic group, or a “—S—” group, a “—Se—” group, a “—Te—” group, or a “═N—” group that can be coordinated to a silver ion by a coordination bond. A heterocyclic group having a partial structure of benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group, purine group, etc. , Thiazole group, oxazole group, benzothiophene group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, tri Jin group, seleno azole group, benzoselenazole group, tellurium azole group, such as benzo tellurium azole group.
Examples of the sulfide group or disulfide group as the adsorptive group include all groups having a partial structure of -S- or -SS-.
The cationic group as the adsorptive group means a group containing a quaternized nitrogen atom, specifically, an ammonio group or a group containing a nitrogen-containing heterocyclic group containing a quaternized nitrogen atom. Examples of the nitrogen-containing heterocyclic group containing a quaternized nitrogen atom include a pyridinio group, a quinolinio group, an isoquinolinio group, an imidazolio group, and the like.
An ethynyl group as an adsorbing group means a —C≡CH group, and the hydrogen atom may be substituted.
The adsorbing group may have an arbitrary substituent.

  Further, specific examples of the adsorbing group include those described in the specifications p4 to p7 of JP-A No. 11-95355.

  In the formula (I), preferred as the adsorptive group represented by A is a mercapto-substituted heterocyclic group (for example, 2-mercaptothiadiazole group, 2-mercapto-5-aminothiadiazole group, 3-mercapto-1,2,4). -Triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4-oxadiazole group, 2-mercaptobenzimidazole group, 1,5-dimethyl-1,2,4-triazolium-3-thiolate group 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3,5-dimercapto-1,2,4-triazole group, 2,5-dimercapto-1,3-thiazole group), or Nitrogen-containing heterocyclic group having —NH— group capable of forming imino silver (> NAg) as a partial structure of heterocyclic ring (for example, benzotriazo Group, benzimidazole group, an indazole group), more preferable as an adsorptive group is a 2-mercaptobenzimidazole group, a 3,5-dimercapto-1,2,4-triazole group.

In formula (I), W represents a divalent linking group. Any linking group may be used as long as it does not adversely affect photographic properties. For example, a divalent linking group composed of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, or a sulfur atom can be used. Specifically, an alkylene group having 1 to 20 carbon atoms (for example, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, etc.), an alkenylene group having 2 to 20 carbon atoms, and an alkynylene group having 2 to 20 carbon atoms. , An arylene group having 6 to 20 carbon atoms (eg, phenylene group, naphthylene group, etc.), —CO—, —SO ₂ —, —O—, —S—, —NR ₁ —, combinations of these linking groups, and the like. It is done. Here, R ₁ represents a hydrogen atom, an alkyl group, a heterocyclic group, or an aryl group.
The linking group represented by W may have an arbitrary substituent.

  In the formula (I), the reducing group represented by B represents a group capable of reducing silver ions, for example, a triple bond group such as formyl group, amino group, acetylene group or propargyl group, mercapto group, hydroxylamines. Hydroxamic acids, hydroxyureas, hydroxyurethanes, hydroxysemicarbazides, reductones (including reductone derivatives), anilines, phenols (chroman-6-ols, 2,3-dihydrobenzofuran-5-ols, (Including aminophenols, sulfonamidophenols, and hydroquinones, catechols, resorcinols, polyphenols such as benzenetriols, bisphenols), acylhydrazines, carbamoylhydrazines, 3-pyrazolidones, etc. Residue with one removed And the like. Of course, these may have an arbitrary substituent.

In the formula (I), the reducing group represented by B shows its oxidation potential by Akira Fujishima “Electrochemical measurement method” (pages 150-208, published by Gihodo) or “The Experimental Chemistry Course” edited by the Chemical Society of Japan, 4th edition ( 9 pages 282-344, Maruzen). For example, by rotating disk voltammetry, specifically, a sample is dissolved in a solution of methanol: pH 6.5 Briton-Robinson buffer = 10%: 90% (volume%), and nitrogen gas is used for 10 minutes. , A glassy carbon rotating disk electrode (RDE) is used as a working electrode, a platinum wire is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, 25 ° C., 1000 rev / min, 20 mV / sec. Can be measured at sweep speed. A half-wave potential (E1 / 2) can be obtained from the obtained voltammogram.
In the present invention, the reducing group represented by B preferably has an oxidation potential in the range of about -0.3 V to about 1.0 V when measured by the above measurement method. More preferably, it is in the range of about -0.1V to about 0.8V, and particularly preferably in the range of about 0V to about 0.7V.

  In the formula (I), the reducing group represented by B is preferably selected from hydroxylamines, hydroxamic acids, hydroxyureas, hydroxysemicarbazides, reductones, phenols, acylhydrazines, carbamoylhydrazines, and 3-pyrazolidones. A residue obtained by removing one hydrogen atom.

  The compound of the formula (I) in the present invention may be one in which a ballast group or polymer chain commonly used in an immobile photographic additive such as a coupler is incorporated. Examples of the polymer include those described in JP-A-1-100530.

  The compound of the formula (I) in the present invention may be a bis form or a tris form. The molecular weight of the compound of formula (I) in the present invention is preferably between 100 and 10000, more preferably between 120 and 1000, particularly preferably between 150 and 500.

  Examples of the compound of formula (I) in the present invention are shown below, but the present invention is not limited thereto.

  Furthermore, specific compounds 1 to 30 and 1 ″ -1 to 1 ″ -77 described in European Patent No. 1308776A2 p73 to p87 are also preferable examples of the compound having an adsorbing group and a reducing group in the present invention.

  These compounds can be easily synthesized according to known methods. As the compound of the formula (I) in the present invention, one kind of compound may be used alone, but it is also preferred to use two or more kinds of compounds at the same time. When two or more kinds of compounds are used, they may be added in the same layer or in different layers, and the addition method may be different.

The compound of the formula (I) in the present invention is preferably added to the silver halide emulsion layer (image forming layer), and more preferably added during preparation of the emulsion. When added at the time of emulsion preparation, it can be added at any time during the process. For example, silver halide grain formation process, before desalting process start, desalting process, chemical ripening Examples include a step before starting, a chemical ripening step, and a step before preparing a finished emulsion. Moreover, it can also add in several steps in these processes. Although it is preferably used for the image forming layer, it may be added to the adjacent protective layer or intermediate layer together with the image forming layer and diffused during coating.
The preferred addition amount largely depends on the above-mentioned addition method and the kind of the compound to be added, but generally 1 × 10 ⁻⁶ mol to 1 mol, preferably 1 × 10 ⁻⁵ mol per mol of photosensitive silver halide. The amount is 5 × 10 ⁻¹ mol or less, more preferably 1 × 10 ⁻⁴ mol or more and 1 × 10 ⁻¹ mol or less.

  The compound of the formula (I) in the present invention can be added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. At this time, the pH may be appropriately adjusted with an acid or a base, and a surfactant may be allowed to coexist. Furthermore, it can also be dissolved in a high boiling point organic solvent and added as an emulsified dispersion. It can also be added as a solid dispersion.

11) Combination of a plurality of silver halides The photosensitive silver halide emulsion in the photothermographic material used in the invention may be only one kind, or two or more kinds (for example, those having different average grain sizes or different halogen compositions). Those having different crystal habits, those having different chemical sensitization conditions) may be used in combination. 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) Coating amount The addition amount of the photosensitive silver halide is preferably 0.03 g / m ² or more and 0.6 g / m ² or less, expressed as the coating silver amount per 1 m ² of the light-sensitive material. / M ² or more and 0.4 g / m ² or less is more preferable, and 0.07 g / m ² or more and 0.3 g / m ² or less is most preferable. The functional silver halide is preferably from 0.01 mol to 0.5 mol, more preferably from 0.02 mol to 0.3 mol, and still more preferably from 0.03 mol to 0.2 mol.

13) Mixing of photosensitive silver halide and organic silver salt Regarding the mixing method and mixing conditions of separately prepared photosensitive silver halide and organic silver salt, the silver halide grains and the organic silver salt that were prepared are respectively stirred at high speed. Prepare an organic silver salt by mixing with a machine, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc., or by mixing photosensitive silver halide that has been prepared at any time during the preparation of the organic silver salt However, there is no particular limitation as long as the effects of the present invention are sufficiently exhibited. In addition, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a preferred method for adjusting photographic characteristics.

14) Mixing of silver halide into coating solution The preferred addition time of silver halide into the image forming layer coating solution is from 180 minutes before application, preferably from 60 minutes to 10 seconds before application. The 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 using a static mixer described in Chapter 8 of Nienow's "Liquid Mixing Technology" (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

(Description of binder)
Any polymer may be used as the binder of the image-forming layer in the present invention. Suitable binders are transparent or translucent and generally colorless, and are natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, and other films. Forming media such as gelatins, gums, 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 (for example, poly (vinyl acetal) (Formal) 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 formed from water, an organic solvent or an emulsion.

  In the present invention, the glass transition temperature of the binder that can be used in combination with the layer containing the organic silver salt is preferably 0 ° C. or higher and 80 ° C. or lower (hereinafter sometimes referred to as a high Tg binder), and preferably 10 ° C. to 70 ° C. Is more preferable, and it is still more preferable that it is 15 degreeC or more and 60 degrees C or less.

In this specification, Tg was 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. The homopolymer glass transition temperature value (Tgi) of each monomer was the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

  Two or more binders may be used in combination 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, the mass average Tg is preferably within the above range.

In the present invention, it is preferable that the image forming layer is coated and dried using a coating solution in which 30% by mass or more of the solvent is water to form a film.
In the present invention, when the image forming 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 image forming layer is further added to an aqueous solvent (aqueous solvent). When it is soluble or dispersible, the performance is improved particularly when it is made of a latex of a polymer having an equilibrium water content of 2 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 and 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, cellosolvs such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

  In the case of a system in which the polymer is not dissolved thermodynamically and exists in a so-called dispersed state, the term aqueous solvent is used here.

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 moisture content, for example, Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Society of Polymer Sciences, Jinshokan) can be referred to.

  The equilibrium water content at 25 ° C. and 60% RH of the binder polymer in 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 still more preferably 0.02%. Desirably, the content is from 1% by mass to 1% by mass.

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. 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. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

  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. The molecular weight of these polymers is 5,000 to 1,000,000, preferably 10,000 to 200,000 in terms of number average molecular weight. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable. A crosslinkable polymer latex is particularly preferably used.

(Specific examples of latex)
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 crosslinkable and the molecular weight description was omitted. Tg represents the glass transition temperature.

-P-1; latex of -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)
-P-4; Latex of -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C)
-P-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C)
-P-6; -St (70) -Bu (27) -IA (3)-latex (crosslinkable)
-P-7; Latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
-P-8; Latex (crosslinkability) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
-Latex (crosslinkable) of P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-
-Latex (molecular weight 80000) of P-10; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-
-Latex of P-11; -VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
-P-12; -Et (90) -MAA (10)-latex (molecular weight 12000)
-P-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130000, Tg 43 ° C)
-P-14; -MMA (63) -EA (35) -AA (2) latex (molecular weight 33000, Tg 47 ° C.)
-P-15; Latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
-P-16; Latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
・ P-17; Latex of -St (61.3) -isoprene (35.5) -AA (3)-(crosslinkability, Tg17 ° C)
-P-18; Latex of -St (67) -isoprene (28) -Bu (2) -AA (3)-(crosslinkability, Tg 27 ° 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.), etc. Examples of poly (esters) include poly (urethane) such as FINETEX ES650, 611, 675, 850 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (above, manufactured by Eastman Chemical). Examples of rubbers include HYDRAN AP10, 20, 30, 40 (manufactured by Dainippon Ink Chemical Co., Ltd.), and examples of rubbers include LACSTAR 7310K, 3307B, 4700H, 7132C (above, Dainippon Ink Chemical Co., Ltd.). (Made by Co., Ltd.), Nipol Lx416, 410, 438C, 2507 (above, Nippon Zeo) As examples of poly (vinyl chloride) such as G351 and G576 (above, manufactured by Nippon Zeon Co., Ltd.), examples of poly (vinylidene chloride) such as L502, L513 (above Examples of poly (olefin) s such as Asahi Kasei Kogyo Co., Ltd. include Chemipearl S120 and SA100 (above Mitsui Petrochemical Co., Ltd.).

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

(Preferred latex)
The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer or a styrene-isoprene copolymer latex. 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 to 99% by mass. Moreover, it is preferable that the polymer latex in this invention contains 1-6 mass% of acrylic acid or methacrylic acid with respect to the sum of styrene and butadiene, More preferably, it contains 2-5 mass%. The polymer latex in the present invention preferably contains acrylic acid. The preferable range of the monomer content is the same as described above. The copolymer ratio in the styrene-isoprene copolymer is the same as that in the styrene-butadiene copolymer.

  Examples of latexes of styrene-butadiene acid copolymer that are preferably used in the present invention include the aforementioned P-3 to P-9,15, commercially available LACSTAR-3307B, 7132C, Nipol Lx416, and the like. Examples of the styrene-isoprene copolymer include the aforementioned P-16 and 17.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose may be added to the image forming layer of the photothermographic material of the 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 image forming layer.

  The organic silver salt-containing layer (that is, the image forming layer) in the present invention is preferably formed using a polymer latex. The amount of binder in the image forming layer is such that the total binder / organic silver salt mass ratio is 1/10 to 10/1, more preferably 1/3 to 5/1, and still more preferably 1/1 to 3/1. Range.

  Further, such an organic silver salt-containing layer is usually a photosensitive layer (image forming layer) containing a photosensitive silver halide that is a photosensitive silver salt. The mass ratio of silver halide is 400-5, more preferably 200-10.

The total binder amount of the image forming layer in the present invention is preferably 0.2 g / m ² or more and 30 g / m ² or less, more preferably 1 g / m ² or more and 15 g / m ² or less, and further preferably 2 g / m ² or more and 10 g. / M ² or less. In the image forming layer of the present invention, a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added.

(Preferable solvent for coating solution)
In the present invention, the solvent of the image forming layer coating solution of the photothermographic 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 of the coating solution is preferably 50% by mass or more, more preferably 70% by mass or more. Examples of preferred solvent compositions include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / There are ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical value is mass%).

(Description of antifogging agent)
Antifogging agents, stabilizers and stabilizer precursors that can be used in the present invention are paragraph No. 0070 of JP-A No. 10-62899, European Patent Publication No. 0803764A, page 20, line 57 to page 21, line 7. And the compounds described in JP-A-9-281737 and JP-A-9-329864, and the compounds described in US Pat. No. 6,083,681 and European Patent 1048875.

(Description of polyhalogen compounds)
Hereinafter, preferred organic polyhalogen compounds that can be used in the present invention will be specifically described. A preferred polyhalogen compound in the present invention is a compound represented by the following general formula (H).
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In General Formula (H), Q represents an alkyl group, an aryl group, or a heterocyclic group, Y represents a divalent linking group, n represents 0 to ₁ , Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron withdrawing group.
In the general formula (H), Q is preferably an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a heterocyclic group containing at least one nitrogen atom (pyridine, quinoline group, etc.).
In the general formula (H), when Q is an aryl group, Q preferably represents a phenyl group substituted with an electron-withdrawing group having a positive Hammett's substituent constant σp. For Hammett's substituent constants, see Journal of Medicinal Chemistry, 1973, Vol. 16, no. 11, 1207-1216 etc. can be referred to. Examples of such an electron withdrawing group include a halogen atom, an alkyl group substituted with an electron withdrawing group, an aryl group substituted with an electron withdrawing group, a heterocyclic group, an alkyl or arylsulfonyl group, acyl Group, alkoxycarbonyl group, carbamoyl group, sulfamoyl group and the like. Particularly preferred as the electron withdrawing group are a halogen atom, a carbamoyl group and an arylsulfonyl group, and a carbamoyl group is particularly preferred.
X is preferably an electron withdrawing group. Preferred electron withdrawing groups are halogen atoms, aliphatic / aryl or heterocyclic sulfonyl groups, aliphatic / aryl or heterocyclic acyl groups, aliphatic / aryl or heterocyclic oxycarbonyl groups, carbamoyl groups, sulfamoyl groups, More preferred are a halogen atom and a carbamoyl group, and particularly preferred is a bromine atom.
Z ₁ and Z ₂ are preferably a bromine atom or an iodine atom, and more preferably a bromine atom.
Y preferably represents -C (= O) -, - SO -, - SO 2 -, - C (= O) N (R) -, - SO 2 N (R) - , more preferably -C ( ═O) —, —SO ₂ —, —C (═O) N (R) —, and particularly preferably —SO ₂ —, —C (═O) N (R) —. R here represents a hydrogen atom, an aryl group or an alkyl group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom.
n represents 0 or 1, and is preferably 1.
In General Formula (H), when Q is an alkyl group, preferred Y is —C (═O) N (R) —, and when Q is an aryl group or a heterocyclic group, preferred Y is —SO ₂ —. is there.
In the general formula (H), a form in which residues obtained by removing a hydrogen atom from the compound are bonded to each other (generally referred to as bis type, tris type, tetrakis type) can also be preferably used.
In the general formula (H), a dissociable group (for example, a COOH group or a salt thereof, a SO ₃ H group or a salt thereof, a PO ₃ H group or a salt thereof), a group containing a quaternary nitrogen cation (for example, an ammonium group or a pyridinium group) Etc.), those having a polyethyleneoxy group, a hydroxyl group or the like as a substituent are also preferred.

  Specific examples of the compound represented by formula (H) in the present invention are shown below.

As polyhalogen compounds that can be used in the present invention other than those described above, US Pat. No. 3,874,946, US Pat. No. 4,756,999, US Pat. No. 5,340,712, US Pat. 119624, 59-57234, JP-A-7-2781, 7-5621, 9-160164, 9-244177, 9-244178, 9-160167, 9- 319022, 9-258367, 9-265150, 9-319022, 10-197988, 10-197989, 11-242304, JP 2000-2963, JP 2000-11270 , JP2000-284410, JP2 Although compounds described as exemplary compounds of the present invention in 00-284212, JP-A-2001-33911, JP-A-2001-31644, JP-A-2001-312027, and JP-A-2003-50441 are preferably used. In particular, compounds specifically exemplified in JP-A-7-2781, JP-A-2001-33911, and JP-A-2001-312027 are preferred.
The compound represented by formula (H) in the present invention is preferably used in the range of 10 ⁻⁴ mol to 1 mol, more preferably 10 ⁻³ , per mol of the non-photosensitive silver salt in the image forming layer. It is preferable to use in the range of not less than 0.5 mol and not more than 0.5 mol, more preferably not less than 1 × 10 ⁻² mol and not more than 0.2 mol.
In the present invention, examples of the method for incorporating the antifoggant into the photothermographic material include the methods described in the method for containing a reducing agent, and the organic polyhalogen compound is also preferably added as a solid fine particle dispersion.

(Other antifoggants)
As other antifogging agents, mercury (II) salt of paragraph No. 0113 of JP-A No. 11-65021, benzoic acid of paragraph No. 0114 of the same, salicylic acid derivative of JP-A No. 2000-206642, formula of JP-A No. 2000-221634 A formalin scavenger compound represented by (S), a triazine compound according to claim 9 of JP-A-11-352624, a compound represented by formula (III) of JP-A-6-11791, 4-hydroxy-6-6 And methyl-1,3,3a, 7-tetrazaindene and the like.

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 light-sensitive material, but the addition layer is preferably added to the layer having the image forming layer, and more preferably added to the image forming layer. The azolium salt may be added at any step during the preparation of the coating solution, and when added to the image forming layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. Immediately before is preferable. 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 for the purpose of controlling development by suppressing or promoting development, improving spectral sensitization efficiency, and improving 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 36-56. Of these, mercapto-substituted heteroaromatic compounds described in JP-A-9-297367, JP-A-9-304875, JP-A-2001-100388, JP-A-2002-303954, JP-A-2002-303951, and the like are preferable. .

2) Toning agent In the photothermographic material of the invention, it is preferable to add a toning agent. For the toning agent, paragraph numbers 0054 to 0055 of JP-A-10-62899, page 21 to 23 of European Patent Publication No. 0803764A1. Line 48, described in JP-A No. 2000-356317 and JP-A No. 2000-187298, and 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, diammonium phthalate) , Sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride) Combinations; phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6-t-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine And 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferable, and a combination of phthalazines and phthalic acids is particularly preferable. Among them, a particularly preferable combination is a combination of 6-isopropylphthalazine and phthalic acid or 4-methylphthalic acid.

3) Plasticizers and lubricants In the present invention, known plasticizers and lubricants can be used to improve film physical properties. In particular, it is preferable to use a lubricant such as liquid paraffin, long chain fatty acid, fatty acid amide, fatty acid ester, etc., in order to improve handling at the time of manufacture and scratch resistance at the time of heat development. In particular, liquid paraffin from which low-boiling components have been removed and fatty acid esters having a branched structure and having a molecular weight of 1000 or more are preferred.
Regarding the plasticizer and lubricant that can be used in the image forming layer and the non-photosensitive layer, JP-A No. 11-65021, paragraph No. 0117, JP-A No. 2000-5137, JP-A No. 2004-219794, JP-A No. 2004-21802, The compounds described in JP-A-2004-334077 are preferred.

4) Dye and Pigment In the image forming layer of the present invention, various dyes and pigments (for example, CI Pigment Blue 60, C.I. Pigment 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.

5) Super-high contrast agent For the formation of a super-high contrast image suitable for printing plate making, it is preferable to add a super-high contrast agent to the image forming layer. As for the ultra-high contrast agent and its addition method and addition amount, the formulas (H ), Compounds of formulas (1) to (3), formulas (A) and (B), compounds of general formulas (III) to (V) described in JP-A-2000-347345 (specific compounds: To 24), the contrast accelerator is described in paragraph No. 0102 of JP-A No. 11-65021 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

  In order to use formic acid or formate as a strong fogging substance, it is preferably contained in an amount of 5 mmol or less, more preferably 1 mmol or less per mol of silver on the side having an image forming layer containing photosensitive silver halide.

When the ultrahigh contrast agent is used in the photothermographic material of the present invention, it is preferable to use an acid formed by hydrating diphosphorus pentoxide or a salt thereof in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametalin An acid (salt) etc. can be mentioned. Examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide particularly preferably include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate.
The amount of acid or salt thereof formed by hydration of diphosphorus pentoxide (the coating amount per 1 m ^{2 of the} photosensitive material) may be a desired amount according to the performance such as sensitivity and fogging, but is 0.1 mg / m ^2. It is preferably 500 mg / m ² or less, more preferably 0.5 mg / m ² or more and 100 mg / m ² or less.
The reducing agent, hydrogen bonding compound, development accelerator and polyhalogen compound in the present invention are preferably used as a solid dispersion, and a preferred method for producing these solid dispersions is described in JP-A-2002-55405. .

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution in the 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 image forming layer in the invention is composed of one or more layers on a support. In the case of a single layer, it consists of an organic silver salt, a photosensitive silver halide, a reducing agent and a binder, and optionally contains additional materials such as toning agents, coating aids and other auxiliary agents. In the case of two or more layers, the first image forming layer (usually a layer adjacent to the support) contains an organic silver salt and a light-sensitive silver halide, and some of the second image forming layer or both layers include Must contain other ingredients. The construction of a multicolor photosensitive photothermographic material may include a combination of these two layers for each color and all components in a single layer as described in US Pat. No. 4,708,928. May be included. In the case of multi-dye multicolor photosensitive photothermographic materials, each image forming layer is generally functional or non-functional between each image forming layer as described in US Pat. No. 4,460,681. By using a sex barrier layer, they are kept distinct from each other.
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 in the photothermographic 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. 2000-171936.
As the binder for the surface protective layer in 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), or 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.

The total coating amount (including water-soluble polymer and latex polymer) of the surface protective layer (per layer) is preferably 0.3 g / m ² or more and 5.0 g / m ² or less as the coating amount (per 1 m ^{2 of the} support). .3g / m ² or more 2.0 g / m ² or less is more preferable.
In addition, it is preferable to use a lubricant such as liquid paraffin and aliphatic ester for the surface protective layer. The amount of the lubricant used is in the range of 1 mg / m ^{2 to} 200 mg / m ² , preferably 10 mg / m ^{2 to} 150 mg / m ² , more preferably 20 mg / m ^{2 to} 100 mg / m ^2. .

2) Antihalation layer In the photothermographic material of the invention, the antihalation layer can be provided on the side farther from the light source than the image forming 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 0.15 to 2, and more preferably 0.2 to 1. 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 the thermal decoloration using such decoloring dye and base precursor, a substance (for example, diphenylsulfone, which lowers the melting point by 3 ° C. (deg) or more when mixed with a base precursor as described in JP-A No. 11-352626). 4-Chlorophenyl (phenyl) sulfone), 2-naphthyl benzoate and the like are preferably used in view of thermal decoloring properties and the like.

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 to 450 nm can be added for the purpose of improving the silver color 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-63-314535, and JP-A-01-61745. No. 1, Japanese Patent Laid-Open No. 2001-100363, and the like.
Such a colorant is usually added in a range of 0.1 mg / m ² or more and 1 g / m ² or less, and the layer to be added is preferably a back layer provided on the opposite side of the image forming layer.
In order to adjust the base color tone, it is preferable to use a dye having an absorption peak at 580 nm to 680 nm. As the dyes for this purpose, azomethine oil-soluble dyes described in JP-A-4-359967 and JP-A-4-359968, which have low absorption intensity on the short wavelength side, and phthalocyanine-based water-soluble dyes described in JP-A-2003-295388 are preferable. The target dye may be added to any layer, but is more preferably added to the non-photosensitive layer on the image forming layer side or the back surface side.

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

4) Matting Agent In the present invention, it is preferable to add a matting agent for improving transportability, and the matting agent is described in paragraph Nos. 0126 to 0127 of JP-A No. 11-65021. The matting agent is preferably 1 mg / m ² or more and 400 mg / m ² or less, more preferably 5 mg / m ² or more and 300 mg / m ² or less when expressed in terms of the coating amount per 1 m ^{2 of the} photothermographic material.
In the present invention, the shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used.
The volume weighted average of the equivalent sphere diameters of the matting agent used for the image forming layer surface is preferably from 0.3 μm to 10 μm, and more preferably from 0.5 μm to 7 μm. Further, the variation coefficient of the size distribution of the matting agent is preferably 5% or more and 80% or less, and more preferably 20% or more and 80% or less. Here, the coefficient of variation is a value represented by (standard deviation of particle size) / (average value of particle size) × 100. Further, two or more kinds of matting agents having different average particle sizes can be used as the matting agent on the image forming layer surface. In this case, the difference in particle size between the matting agent having the largest average particle size and the smallest matting agent is preferably 2 μm or more and 8 μm or less, and more preferably 2 μm or more and 6 μm or less.
The volume weighted average of the equivalent sphere diameters of the matting agent used for the back surface is preferably 1 μm or more and 15 μm or less, and more preferably 3 μm or more and 10 μm or less. The variation coefficient of the size distribution of the matting agent is preferably 3% or more and 50% or less, and more preferably 5% or more and 30% or less. Further, two or more kinds of matting agents having different average particle sizes can be used as the matting agent for the back surface. In that case, the difference in particle size between the matting agent having the largest average particle size and the smallest matting agent is preferably 2 μm or more and 14 μm or less, and more preferably 2 μm or more and 9 μm or less.

  The matting degree of the image forming layer surface may be any as long as no stardust failure occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, particularly preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily determined 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 photothermographic material, the layer functioning as the outermost surface layer, or a layer close to the outer surface, and also contained in a layer acting as a so-called protective layer. It is preferred that

5) Polymer Latex When the photothermographic material of the present invention is used for printing applications in which dimensional change is a problem, it is preferable to use a polymer latex for the surface protective layer or the back layer. 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 A latex of xyl acrylate (25.4% by weight) / styrene (8.6% by weight) / 2-hydroxyethyl methacrylate (5.1% by weight) / acrylic acid (2.0% by weight) 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. Furthermore, as a binder for the surface protective layer, a combination of polymer latex described in Japanese Patent Application No. 11-6872, the technique described in Paragraph Nos. 0021 to 0025 of Japanese Patent Application Laid-Open No. 2000-267226, and Japanese Patent Application No. 11-6872. The technology described in paragraph numbers 0027 to 0028 of the specification and the technology described in paragraph numbers 0023 to 0041 of JP 2000-19678 may be applied.
The ratio of the polymer latex in the surface protective layer is preferably 10% by mass or more and 90% by mass or less, and particularly preferably 20% by mass or more and 80% by mass or less of the total binder.

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.
In addition, it is also preferable to use ammonia in combination with a nonvolatile base such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. 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 image forming layer, protective layer, and back layer in 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 (vinylsulfoneacetamide), N, N-propylenebis (vinylsulfoneacetamide), 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 vinylsulfone compounds such as JP-A-62-289048 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 As for the surfactant applicable to the present invention, paragraph No. 0132 of JP-A No. 11-65021, paragraph No. 0133 of the solvent, paragraph No. 0134 of the support, and antistatic or conductive layer Are described in paragraph No. 0135 of the same number, paragraph No. 0136 of the same number about the method of obtaining a color image, paragraph numbers 0061 to 0064 of JP-A No. 11-84573 and paragraph numbers 0049 to 0062 of JP-A No. 2001-83679 about the slip agent. ing.
In the present invention, it is preferable to use a fluorosurfactant. 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 photothermographic material of the present invention, it is preferable to use fluorine-based surfactants described in JP-A Nos. 2002-82411, 2003-057780, and 2003-149766. In particular, the fluorosurfactants described in JP-A-2003-057780 and JP-A-2001-264110 are preferable in terms of charge adjustment ability, stability of the coated surface, and smoothness when coating and production is performed with an aqueous coating solution. The fluorine-based surfactant described in JP-A No. 2001-264110 is most preferable because it has a high charge adjusting ability and requires a small amount of use.
In the present invention, the fluorosurfactant can be used on either the image forming layer surface or the back surface, and is preferably used on both surfaces. Further, it is particularly preferable to use in combination with a conductive layer containing the above-described metal oxide. In this case, sufficient performance can be obtained even if the amount of the fluorosurfactant used on the surface having the conductive layer is reduced or removed.
The preferred amount of the fluorocarbon surfactant is an image forming layer side, the range to the back surface each ^{0.1mg / m 2 ~100mg / m 2} , more preferably 0.3mg / m ² ~30mg / m ² range, even more preferably from ^{1mg / m 2 ~10mg / m 2} . In particular JP fluorocarbon surfactant described in JP-A No. 2001-264110 is effective, and preferably in the range of ^{0.01mg / m 2 ~10mg / m 2} , more in the range of 0.1mg / m ² ~5mg / m ² preferable.

9) Antistatic agent In this invention, it is preferable to have a conductive layer containing a metal oxide or a conductive polymer. The antistatic layer may serve as an undercoat layer, a back layer surface protective layer, or the like, or may be provided separately. As the conductive material for the antistatic layer, a metal oxide in which conductivity is improved by introducing oxygen defects or different metal atoms into the metal oxide is preferably used. Examples of metal oxides are preferably ZnO, TiO ₂ and SnO _2. Addition of Al and In to ZnO, addition of Sb, Nb, P and halogen elements to SnO ₂ , and addition to TiO _2. For example, addition of Nb, Ta or the like is preferable.
In particular, SnO ₂ added with Sb is preferable. The amount of different atoms added is preferably in the range of 0.01 mol% to 30 mol%, and more preferably in the range of 0.1 mol% to 10 mol%. The shape of the metal oxide may be spherical, needle-like, or plate-like, but the long axis / uniaxial ratio is 2.0 or more, preferably 3.0 to 50 in terms of the effect of imparting conductivity. Good. Range amount preferably of 1mg / m ² ~1000mg / m ² of metal oxide, more preferably 10mg / m ² ~500mg / m ² range, more preferably at 20mg / m ² ~200mg / m ² It is a range.
The antistatic layer in the present invention may be disposed on either the image forming layer surface side or the back surface side, but is preferably disposed between the support and the back layer. Specific examples of the antistatic layer are disclosed in paragraph No. 0135 of JP-A No. 11-65021, JP-A Nos. 56-143430, 56-143431, 58-62646, No. 56-120519 and JP-A No. 11-84573. Paragraph Nos. 0040 to 0051, US Pat. No. 5,575,957, and JP-A-11-223898, paragraph Nos. 0078 to 0084.

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. 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. When the image forming layer or the back layer is applied to the support, the water content of the support is preferably 0.5 wt% or less.

11) Other additives An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid may be further added to the photothermographic material. Various additives are added to either the image forming 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 coated simultaneously 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. . In the present invention, particularly preferred coating methods are those described in JP-A Nos. 2001-194748, 2002-153808, 2002-153803, and 2002-182333.

The image forming layer coating solution in the invention is preferably a so-called thixotropic fluid. Regarding this technique, JP-A-11-52509 can be referred to. In the image forming layer coating solution of the present invention, the viscosity at a shear rate of 0.1 S ⁻¹ 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. 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.

In the case of preparing the coating liquid, a known in-line mixer or implant mixer is preferably used when mixing two kinds of liquids. A preferable in-line mixer in the present invention is described in JP-A No. 2002-85948, and an implant mixer is described in JP-A No. 2002-90940.
The coating solution in the present invention is preferably subjected to defoaming treatment in order to keep the coated surface state good. A preferable defoaming treatment method in the present invention is the method described in JP-A No. 2002-66431.
When applying the coating solution, it is preferable to perform static elimination in order to prevent adhesion of dust, dust, and the like due to electric resistance of the support. An example of a preferable static elimination method in the present invention is described in JP-A No. 2002-143747.
In the present invention, it is important to precisely control the drying air and the drying temperature in order to dry the non-setting image forming layer coating solution. Preferred drying methods in the present invention are described in detail in JP-A Nos. 2001-194749 and 2002-139814.
The photothermographic material of the present invention is preferably subjected to a heat treatment immediately after coating and drying in order to improve film formability. The temperature of the heat treatment is preferably in the range of 60 ° C. to 100 ° C. as the film surface temperature, and the heating time is preferably in the range of 1 second to 60 seconds. A more preferable range is a film surface temperature of 70 ° C. to 90 ° C. and a heating time of 2 seconds to 10 seconds. A preferable heat treatment method in the present invention is described in JP-A No. 2002-107872.
In order to stably and continuously produce the photothermographic material of the present invention, the production methods described in JP-A Nos. 2002-156728 and 2002-182333 are preferably used.

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

13) Packaging material The photothermographic material of the present invention is a packaging material having a low oxygen permeability and / or moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curling and curling. It is preferable to package. 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, more preferably 1.0 mL / atm · m ² · day or less. is there. The moisture permeability is preferably 10 g / atm · m ² · day or less, more preferably 5 g / atm · m ² · day or less, and still more preferably 1 g / atm · m ² · day or less.
Specific examples of the packaging material having low oxygen permeability and / or moisture permeability are disclosed in, for example, JP-A-8-254793. This is a packaging material described in JP-A-2000-206653.
14) Other available technologies

  Techniques that can be used for the photothermographic material of the present invention include EP80364A1, EP883022A1, WO98 / 36322, JP56-62648, 58-62644, JP9-43766, and 9-. 281637, 9-297367, 9-304869, 9-311405, 9-329865, 10-10669, 10-62899, 10-69023, 10-186568, 10-90823, 10-171106, 10-186565, 10-186567, 10-186567 to 10-186572, 10-197974, 10-197982, 10 -197983, 10-197985 to 10-197987, 10- 07001, 10-207004, 10-221807, 10-282601, 10-288823, 10-288824, 10-307365, 10-312038, 10-339934 11-7100, 11-15105, 11-24200, 11-24201, 11-30201, 11-30832, 11-84574, 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, 11-305384, 11-30538 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, 2001-200414, 2001-234635, 2002-020699, 2001-275471, 2001-275461, 2000-313204, 2001-292844, 2000-324888, 2001-293864, 2001-348546, JP No. 2000-187298 is also mentioned.

In the case of a multicolor color photothermographic material, each image-forming layer is generally functional or photosensitive between each photosensitive layer (image-forming layer) as described in US Pat. No. 4,460,681. By using non-functional barrier layers, they are kept separate from each other.
The construction in the case of a multicolor color photothermographic material may include a combination of these two layers for each color and all within a single layer as described in US Pat. No. 4,708,928. Ingredients may be included.

(Image forming method)
1) Exposure Red to infrared emission He—Ne laser, red semiconductor laser, blue to green emission Ar ⁺ , He—Ne, He—Cd laser, blue semiconductor laser. Preferred is a red to infrared semiconductor laser, and the peak wavelength of the laser light is 600 nm to 900 nm, preferably 620 nm to 850 nm.
On the other hand, in recent years, in particular, a module in which an SHG (Second Harmonic Generator) element and a semiconductor laser are integrated and a blue semiconductor laser have been developed, and a laser output device in a short wavelength region has been closed up. The blue semiconductor laser is expected to increase in demand in the future because high-definition image recording is possible, the recording density is increased, and a stable output is obtained with a long lifetime. The peak wavelength of the blue laser light is preferably 300 nm to 500 nm, particularly preferably 400 nm to 500 nm.
It is also preferable that the laser light is oscillated in a vertical multi by a method such as high frequency superposition.

2) Photothermographic 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. A preferred development temperature is 80 ° C to 250 ° C, preferably 100 ° C to 140 ° C, and more preferably 110 ° C to 130 ° C. The development time is preferably 1 second to 60 seconds, more preferably 3 seconds to 30 seconds, still more preferably 5 seconds to 25 seconds, and 7 seconds to 15 seconds.

  Either a drum type heater or a plate type heater may be used as the thermal development method, but the plate type heater method is more preferable. The thermal development method using the plate heater method is preferably the method described in JP-A-11-133572, and a visible image is obtained by bringing the photothermographic material having a latent image formed thereon into contact with the heating means in the thermal development unit. In the heat development apparatus, 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 press roller is disposed between the press roller and the plate heater. A photothermographic apparatus for carrying out heat development by passing a photothermographic material. It is preferable to divide the plate heater into two to six stages and lower the temperature at the tip by about 1 ° C. to 10 ° C. For example, there are examples in which four sets of plate heaters that can be independently controlled are used and controlled to 112 ° C., 119 ° C., 121 ° C., and 120 ° C., respectively. Such a method is also described in JP-A No. 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 the change in the shape of the support of the photothermographic material due to the heating.

  In order to reduce the size of the heat developing machine and shorten the heat development time, it is preferable to be able to control the heater more stably. In addition, the exposure of one sheet of photosensitive material is started from the top and the exposure is finished to the back end. It is desirable to start the heat development before the time. Imagers capable of rapid processing preferable for the present invention are described in, for example, JP-A Nos. 2002-289804 and 2003-285455. If this imager is used, for example, heat development can be performed in 14 seconds with a three-stage plate heater controlled at 107 ° C.-121 ° C.-121 ° C. The output time of the first sheet is shortened to about 60 seconds. be able to. For such rapid development processing, it is preferable to use the photothermographic material-2 of the present invention in combination with high sensitivity and less susceptible to environmental temperature.

3) System As a medical laser imager provided with an exposure part and a heat development part, Fuji Medical Dry Laser Imager FM-DPL and DRYPIX7000 can be exemplified. Regarding FM-DPL, Fuji Medical Review No. 8, pages 39 to 55, and it goes without saying that these techniques are applied as a laser imager of the photothermographic material of the present invention. Further, it can also be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Film Medical Co., Ltd. as a network system adapted to the DICOM standard.

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

  EXAMPLES The present invention will be specifically described below 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 discharge treatment Using a solid state corona discharge treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at room temperature at 20 m / min. 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 formulation a (for image forming layer side undercoat layer)
・ 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 mass solution 11.0 g
・ MP-1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
・ Distilled water 931mL

Formulation b (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 mass aqueous solution)
5.2g
・ 10 mL of 1% by weight aqueous solution of sodium laurylbenzenesulfonate
・ Polystyrene particle dispersion (average particle size 2 μm, 20 mass%) 0.5 g
-854 mL of distilled water

Formulation c (for back side second 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. Metroz TC-5 (2% by weight aqueous solution) 10 g
・ 10% 1% aqueous solution of sodium dodecylbenzenesulfonate
・ NaOH (1% by mass) 7 g
・ Proxel (Abyssia) 0.5g
・ 881mL 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 liquid formulation a is applied to one side with a wire bar at a wet coating amount of 6.6 mL / m ² And then dried at 180 ° C. for 5 minutes, and then the undercoat coating solution formulation b was applied to the back surface) with a wire bar so that the wet coating amount was 5.7 mL / m ² . Dry at 5 ° C. for 5 minutes, and apply the above-mentioned undercoat coating liquid formulation c on the back surface with a wire bar so that the wet coating amount is 8.4 mL / m ² and dry at 180 ° C. for 6 minutes to produce an undercoat support. did.

(Back layer)
1) Preparation of Back Layer Coating Liquid << Preparation of Solid Precursor Solid Fine Particle Dispersion (a) >>
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.

<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 Co., Ltd. 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.

2) 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 a 3% by weight aqueous solution of sodium polystyrenesulfonate, 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 an antihalation layer coating solution having a finished solution amount of 773 mL. The pH value of the finished liquid was 6.3.

3) Preparation of back surface protective layer coating solution Keep the container at 40 ° C., add 43 g of gelatin (PZ gelatin made by Miyagi Chemical Co., Ltd.) with isoelectric point 4.8, 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 sodium polystyrenesulfonate solution, 2.4 mL of a 2% by mass solution of a fluorosurfactant (F-1), 2.4 mL of a 2% by mass solution of a fluorosurfactant (F-2), an ethyl acrylate / acrylic acid copolymer (copolymerization mass) Ratio 96.4 / 3.6) A latex 20% by mass solution 30 mL 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 >>
To a solution of 1421 mL of distilled water, 3.1 mL of a 1% by mass potassium bromide solution was added, and a solution containing 3.5 mL of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 30 ° C., the solution A diluted with 92.2 mL of distilled water added to 22.22 g of silver nitrate, 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 and 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 were 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 a total amount of 1.2 × 10 ⁻³ moles of the sensitizing dyes A and B per mole 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 solution in methanol with a methanol solution of 4.8 per mol of silver. × 10 ^-4 mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution with 5.4 × 10 ^-4 mol and 1- (3-methyl with respect to 1 mol of silver Silver halide emulsion 1 was prepared by adding 8.5 × 10 ⁻⁴ mol of ureidophenyl) -5-mercaptotetrazole in an aqueous solution to 1 mol of silver.

  The grains in the prepared silver halide emulsion were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.042 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 >>
Prepare silver halide emulsion 2 in the same manner as silver halide emulsion 1 except that chemical sensitization was performed by adding selenium sensitizer B in the amount shown in Table 2 instead of tellurium sensitizer C. did.

<< Preparation of silver halide emulsions 3-7 >>
Similar to silver halide emulsion 1, except that instead of tellurium sensitizer C, the chemical sensitizer of the present invention (shown in Table 1) was added at 9.5 × 10 ⁻⁵ mole per mole of chemistry. Sensitized silver halide emulsions 3 to 7 were prepared.

<< Preparation of Mixed Emulsions 1-7 for Coating Solution >>
Each silver halide emulsion was dissolved, and benzothiazolium iodide was added in a 1% by mass aqueous solution at 7 × 10 ⁻⁴ mol per mol of silver.
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.
Adsorbing redox compounds 1 and 2 having an adsorbing group and a reducing group were added in an amount of 5 × 10 ⁻³ mol per mol of silver halide.
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 A >>
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. To obtain a sodium behenate solution A. 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.

<< Preparation of fatty acid silver dispersion B >>
<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 B>
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 stirring, the total amount of the previous sodium behenate solution B and the total amount of silver nitrate aqueous solution were kept 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 B is started. After the addition of the aqueous silver nitrate solution is completed, only the sodium behenate solution B is added for 14 minutes and 15 seconds. 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 piping of the addition system of the sodium behenate solution B 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 B and the addition position of the aqueous silver nitrate solution were arranged symmetrically with respect to the stirring axis, and were adjusted so as not to contact the reaction solution.

After completion of the addition of the sodium behenate solution B, 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, sphere equivalent diameter. The crystal had a coefficient of variation of 11%. (A, b, and c are the provisions of the text)

  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-1 dispersion >>
10 kg of water was added to 16 kg of a 10% by weight aqueous solution of reducing agent-1 (2,2′-methylenebis- (4-ethyl-6-tert-butylphenol)) and denatured 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 masses 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. The 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 20 wt% aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of 20 wt% 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 weight 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% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 ( 14.28 kg of a 70% by weight aqueous solution of 6-isopropylphthalazine) was added to prepare a 5% by weight solution of phthalazine compound-1.

9) Preparation of mercapto compound << Preparation of aqueous solution of mercapto compound-1 >>
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 / L, 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 were put, and the reaction vessel was sealed and stirred. Stir at a speed of 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 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 1500g 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 stirrer 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. The polymerization conversion rate at this time was 90% from the solid content measurement. 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 liquid 1) Preparation of image forming layer coating liquid 1-1 to 1-7 1000 g of fatty acid silver dispersion A obtained above, 135 mL of water, 35 g of pigment-1 dispersion, 19 g of organic polyhalogen compound-1 dispersion, 58 g of organic polyhalogen compound-2 dispersion, 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, and dispersing agent-2 dispersion 75 g of the product, 53 g of the hydrogen bonding compound-1 dispersion, 4.8 g of the development accelerator-2 dispersion, 9 mL of the mercapto compound-1 aqueous solution, and 27 mL of the mercapto compound-2 aqueous solution are sequentially added. The image forming layer coating solution, to which 118 g of any one of 1 to 7 was added and mixed well, was fed to the coating die as it was and coated.

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 image forming layer coating liquids 2-1 to 2-7 1000 g of fatty acid silver dispersion B obtained above, 135 mL of water, 36 g of pigment-1 dispersion, 25 g of organic polyhalogen compound-1 dispersion, organic polyhalogen compound -2 dispersion 39 g, phthalazine compound-1 solution 171 g, SBR latex (TP-1) solution 318 g, isoprene latex (TP-2) solution 742 g, reducing agent-2 dispersion 153 g, hydrogen bonding compound-1 dispersion 22 g Then, 4.8 g of development accelerator-1 dispersion, 5.2 g of development accelerator-2 dispersion, 2.1 g of color tone modifier-1 dispersion, and 8 mL of mercapto compound-2 aqueous solution were sequentially added. The image forming layer coating solution, in which 140 g of any of the mixed emulsions 1 to 7 was added and mixed well, was fed to the coating die as it was and coated.
The viscosity of the image forming layer coating solution was 35 [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 38, 49, 48, 34, 25 [mPa · s] at shear rates of 0.1, 1, 10, 100, 1000 [1 / second], respectively. s].

  The amount of zirconium in the coating solution was 0.30 mg per 1 g of silver.

3) 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) 18.5% by weight aqueous solution 33 g, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5% by weight aqueous solution 27 mL, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8 / 28/5/2) 27% 5% aqueous solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.) in 4200 mL of latex 19% by weight solution, 135 mL of 20% aqueous solution of diammonium phthalate, total amount 10000g Water is added to the NaO so that the pH is 7.5. An intermediate layer coating solution was prepared by adjusting with H, and the solution was 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).

4) 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 a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio) 57/8/28/5/2) 180 g of latex 19 wt% solution, 46 mL of 15 wt% methanol solution of phthalic acid, and 5.4 mL of 5 wt% aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate 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).

5) 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 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 mass solution of fluorosurfactant (F-1), 5.5 mL of 1% by mass aqueous solution of fluorosurfactant (F-2), di (2-ethylhexyl sulfosuccinate) ) 28mL of 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. Production of photothermographic material 1) Production of photothermographic material 1-1 to 1-7 Image forming layer using image forming layer coating liquid 1-1 to 1-7 from the undercoat surface on the opposite side to the back surface, The intermediate layer, the surface protective layer first layer, and the surface protective layer second layer were simultaneously coated in the order of the slide bead coating method to prepare a photothermographic material sample. 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 5.42
Pigment (C.I. Pigment Blue 60) 0.036
Polyhalogen compound-1 0.12
Polyhalogen compound-2 0.25
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 0.012
Silver halide (as Ag) 0.10

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 sample produced as described above was designated as a photothermographic material 1-1. Samples using the silver halide emulsions 2 to 6 prepared by changing the chemical sensitizers as shown in Table 1 to the photothermographic material 1-1 were also prepared in the same manner, and the photothermographic materials 1-2 to 1 were used. It was set to -6.

2) Preparation of photothermographic materials 2-1 to 2-7 For the photothermographic materials 1-1 to 1-7, the image forming layer coating solution was changed to image forming layer coating solutions 2-1 to 2-7. Photothermographic materials 2-1 to 2-7 were prepared in the same manner except that. The coating amount (g / m ² ) of each compound in the image forming layer at this time is as follows.

Fatty acid silver 5.27
Pigment (C.I. Pigment Blue 60) 0.036
Polyhalogen compound-1 0.14
Polyhalogen compound-2 0.28
Phthalazine Compound-1 0.18
SBR latex (TP-1) 2.83
Isoprene latex (TP-2) 6.60
Reducing agent-2 0.77
Hydrogen bonding compound-1 0.112
Development accelerator-1 0.019
Development accelerator-2 0.016
Color tone adjusting agent-1 0.006
Mercapto compound-2 0.003
Silver halide (as Ag) 0.10

  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%, and stored at room temperature for 2 weeks. The following evaluation was performed.
<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 · 25 ° C · day;
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day.

2) Exposure and development of photothermographic material The photothermographic materials 1-1 to 1-7 are mounted on Fuji Medical Co., Ltd. dry laser imager FM-DPL (with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)). Exposure and thermal development (total of 24 seconds with four panel heaters set to 112 ° C-119 ° C-121 ° C-121 ° C) were performed.
Photothermographic materials 2-1 to 2-7 were exposed and thermally developed (107 ° C. to 121 ° C. to 121 ° C.) with a dry laser imager DRYPIX7000 (mounted with a 660 nm semiconductor laser having a maximum output of 50 mW (IIIB)). (Total 14 seconds with 3 panel heaters set at 0 ° C.).

3) Evaluation of photographic performance The density of an image obtained by a Macbeth densitometer was measured, and a density characteristic curve with respect to the exposure amount was prepared. The density of the part not exposed to the laser was defined as fog, and the density of the part exposed at the maximum exposure amount was defined as Dmax. Further, the reciprocal of the exposure amount for obtaining the density of Fog + 1.0 was defined as sensitivity, and expressed as a relative value based on the sensitivity of sample 1-1.

The printout performance was evaluated as follows. The sample after the heat development treatment was allowed to stand for 10 days under a fluorescent lamp with an illuminance of 1000 lux in an environment of 25 ° C. and 60% RH, and the increase in fog (difference ΔFog between the initial and storage) was measured.
The obtained results are shown in Table 1.

  From the results of Table 1, the chemical sensitizer of the present invention is effective in a small amount as compared with the comparative compound. By using the chemical sensitizer of the present invention, a preferable photothermographic material having high sensitivity and high Dmax. was gotten. Further, the photothermographic material of the present invention has an unexpected result that printout fog is improved.

Example 2
1. Preparation of coated sample In the photothermographic materials 2-1 to 2-7 used in Example 1, the reducing agent-2 was changed in an equimolar amount to the compound of the general formula (R) (R-17), and a polyhalogen compound- Photothermographic materials 3-1 to 3-7 were prepared in the same manner except that 2 was changed in an equimolar amount to the compound (H-17) of the general formula (H). Compound (R-17) and compound (H-17) were added by preparing dispersions in the same manner as reducing agent-2 and polyhalogen compound-2, respectively.
2. Performance Evaluation As a result of evaluation in the same manner as in Example 1, the sample of the chemical sensitizer of the present invention showed excellent performance as in Example 1.

Example 3
1. Preparation of silver halide emulsion 1) Preparation of silver halide emulsion 11 A tabular silver iodobromide emulsion was prepared as follows.
1500 mL of an aqueous solution containing 4.1 g of KBr and 14.1 g of phthalated gelatin was kept at 40 ° C. and stirred. An aqueous solution containing AgNO ₃ (2.9 g) and KBr (2.0 g) and KI (0.39 g) was added over 40 seconds. After adding an aqueous solution containing 35.5 g of phthalated gelatin, the temperature was raised to 58 ° C. After that, an AgNO ₃ (63.7 g) aqueous solution and a KBr aqueous solution containing KI were added as the first growth while the flow rate was accelerated by the double jet method. The concentration of KI was adjusted so that the silver iodide content was 0.5 mol%. The pAg during operation was maintained at 8.9. On the way, potassium hexachloroiridate (III) and sodium benzenethiosulfonate were added. Thereafter, an aqueous AgNO ₃ solution (7.4 g) and an aqueous KBr solution containing KI were added over 5 minutes as the outermost layer growth. The concentration of KI was adjusted so that the silver iodide content was 10 mol%.
At this time, pAg was maintained at 8.9. Normal washing was performed, and phthalated gelatin was added so that the amount of silver and gelatin contained in 1 kg of emulsion was equal to that of silver halide emulsion 2A, and adjusted to pH 5.9 and pAg 8.4 at 40 ° C.

While maintaining the silver halide dispersion 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 57 ° C. after 40 minutes. After 20 minutes of temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mole per mole of silver halide, and further 5 minutes later, tellurium sensitizer C was added to the silver halide 1 in methanol solution. The mixture was aged for 91 minutes by adding 4.5 × 10 ⁻⁵ mol per mol. Then, spectral sensitizing dyes -3 2.2 × 10 ^-3 mol per mol of silver halide, the sensitizing dye -1 and -2 respectively 1 mol of silver halide with respect to 1.0 × 10 ^{- 4} mol was added, and calcium chloride was further added. After 1 minute, 1.3 mL of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to 1 mol of silver with a methanol solution. ^Per mole of 4.8 × 10 ⁻⁴ mole, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution to 5.4 × 10 ⁻⁴ mole and 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added in an aqueous solution to 8.5 × 10 ⁻⁴ mol per mol of silver.

  The obtained silver halide grains had an average equivalent circle diameter of 0.95 μm, an average equivalent circle diameter variation coefficient of 12.6%, an average thickness of 0.055 μm, an average aspect ratio of 17.2 and tabular grains having a total projected area. It accounted for over 80%. The equivalent sphere diameter was 0.42 μm.

2) Preparation of silver halide emulsions 12 to 17 Silver halide emulsions 12 to 17 were prepared by changing the tellurium sensitizer C to the chemical sensitizer shown in Table 2 in the preparation of the silver halide emulsion 10. The obtained silver halide grains were tabular grains having the same high aspect ratio as that of the silver halide emulsion 10.

3) Preparation of coating emulsions 11 to 17 Coating emulsions 11 to 17 were prepared using the silver halide emulsions 11 to 17 in the same manner as the preparation of the coating emulsion of Example 1.

2. Preparation of Coating Samples Samples 31 to 37 were prepared in the same manner as Samples 2-1 to 2-7 of Example 1 except that the mixed emulsions 11 to 17 for coating solutions were used as the mixed emulsions for coating solution.

3. Performance evaluation X ray ortho screen HG-M manufactured by FUJIFILM Corporation (using terbium-activated gadolinium oxysulfide as a phosphor. Emission peak wavelength 545 nm) and a sample are stacked, and X-ray exposure for 0.05 seconds is performed. 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. After the exposure, heat development was performed in the same manner as in Example 1 to evaluate the performance.
The obtained results are shown in Table 2.
Similar to Example 1, samples prepared using the compounds of the present invention showed excellent performance.

Example 4
1. Preparation of silver halide emulsion As in emulsions 12 and 13 of Example 3, except that during chemical sensitization, potassium thiocyanate was further added to selenium sensitizer B or Ch-1 of the present invention for 3 moles per mole of silver halide. × 10 ^-3 mol, 6 × 10 ^-6 mol of gold sensitizer chloroauric acid per mol of silver halide, and 5 × 10 ^-5 mol of sodium thiosulfate as sulfur sensitizer per mol of silver halide Were added to prepare silver halide emulsions 21 and 22 subjected to gold-sulfur selenium sensitization.
2. Preparation of coated samples Samples 41 and 42 were prepared in the same manner except that emulsions 21 and 22 were used instead of emulsions 12 and 13 of Example 3.
3. Performance Evaluation When the same evaluation as in Example 3 was performed, the sample 42 of the present invention showed excellent performance.

Claims (11)

A photothermographic material 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, the compound represented by the following general formula (1) A photothermographic material comprising:
Formula (1) E ¹ -Ch-E ²
(In General Formula (1), Ch represents a sulfur atom, a selenium atom, or a tellurium atom. E ¹ and E ² are each independently a group represented by General Formula (2) to General Formula (5) below. Each of which may be the same or different, provided that E ¹ and E ² are not simultaneously selected from the group represented by the formula (2).);

(In General Formula (2), Z represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, —OR ¹ or —NR ² R ³ , and R ^{1 to} R ³ represent an alkyl group, an alkenyl group, An alkynyl group, an aryl group, or a heterocyclic group, in formula (3), L represents a divalent linking group, EWG represents an electron withdrawing group, and in formula (4), A ¹ represents oxygen Represents an atom, a sulfur atom or —N (R ⁷ ) —, and R ^{4 to} R ⁷ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group. ² represents an oxygen atom, a sulfur atom or —N (R ¹¹ ) —, R ⁸ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group or an acyl group, and R ^{9 to} R ^11. Is a hydrogen atom, an alkyl Represents a group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, X represents a substituent which can be substituted on the benzene ring, n represents an integer of 0 to 4. When n is 2 or more, X is Same or different.)   2. The photothermographic material according to claim 1, wherein the photosensitive silver halide is chemically sensitized with the compound represented by the general formula (1). ^3. The photothermographic material according to claim 1, wherein at least one of E ¹ and E ² is a group selected from the general formula (4) or (5). 4. The photothermographic material according to claim 3, wherein at least one of E ¹ and E ² is a group selected from the general formula (5).   The photothermographic material according to claim 1, wherein the Ch is a selenium atom.   The photothermographic material according to claim 1, wherein the Ch is a tellurium atom. The photothermographic material according to claim 1, wherein the photosensitive silver halide is gold sensitized. 8. The heat according to claim 1, wherein the water-soluble thiocyanate is contained in an amount of 1 × 10 ⁻³ mol to 8 × 10 ⁻¹ mol per mol of silver halide. Development photosensitive material.   The photothermographic material according to any one of claims 1 to 8, wherein the photosensitive silver halide has a silver bromide content of 70 mol% or more.   The photothermographic material according to claim 9, wherein the photosensitive silver halide has an average grain size of 0.01 μm to 0.2 μm.   10 to 50% of the total projected area of the photosensitive silver halide is a tabular grain having an aspect ratio of 2 or more, and has an average grain size of 0.3 μm or more and 8.0 μm or less. The photothermographic material according to claim 1.