JP2006330348A - Heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high maximum density, high sensitivity and little fog, giving a good cold black tone as a silver tone, and excellent in stability to heat and light during image storage. <P>SOLUTION: The heat developable photosensitive material has on a support an image forming layer containing a non-photosensitive organic silver salt, a silver halide, a reducing agent for silver ions and a binder, wherein the heat developable photosensitive material contains a compound represented by formula (1) wherein W represents a substituent other than hydroxyl, H or halogen; R<SB>1</SB>-R<SB>4</SB>, R<SB>6</SB>and R<SB>7</SB>each represent H, a substituent or halogen; X represents O, S or N-R<SB>5</SB>, and R<SB>5</SB>represents H or a substituent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photothermographic material, and more particularly to a photothermographic material having high maximum density and sensitivity, low fog, a cool black tone having a good silver tone, and excellent image stability.

  In recent years, there has been a strong demand for a photosensitive material free from a developing solution waste in terms of environmental protection and workability in the medical and printing fields. Examples of this technique include US Pat. Nos. 3,152,904, 3,487,075 and D.I. The method described in “Dry Silver Photographic Materials” by Morgan (Handbook of Imaging Materials, Marcel Dekker, Inc., page 48, 1991) and the like is well known. Since these photosensitive materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

  The photothermographic material has a much larger number of kinds and added amounts of built-in chemical substances than the conventional photosensitive material processed by liquid processing, and accordingly, the film thickness of the photosensitive layer and the non-photosensitive layer is increased. It tends to increase. As a result, the coating process or the drying process at the time of manufacturing the photothermographic material requires a lot of time, and the productivity is lowered.

  In general, it is widely known that reducing the amount of silver is effective in reducing the film thickness in a photosensitive material. However, mere reduction of the amount of silver is not preferable because it causes a decrease in image density. In order to reduce the silver amount and not reduce the image density, it is effective to increase the number of development points per unit area and increase the covering power. 2. Description of the Related Art Conventionally, a technology for obtaining high image density with a low silver amount by increasing the covering power using “infectious development” with a nucleating agent has been established for photosensitive materials for printing. For example, the method is described in Japanese Patent Laid-Open No. 10-512061 and Japanese Patent Laid-Open No. 11-511571. However, many of the light-sensitive materials using a conventionally known nucleating agent have poor storage stability, and the color tone of the formed image silver is yellowish.

  Photothermographic materials are frequently used especially for medical diagnostic applications because of their convenience. Medical diagnostic images are required to have fine picture quality, and therefore require high image quality with excellent sharpness and graininess. In addition, cold black images are preferred from the viewpoint of ease of diagnosis. Although it is difficult to produce a pure black color tone with this photothermal image forming system using organic silver salt, the color tone is adjusted with a color tone agent or the like, but the color tone control is not sufficient and an improvement is desired. Patent Documents 1 and 2 disclose a combination of a specific reducing agent and a specific compound as a technique for improving this drawback, but the improvement effect is hardly sufficient, and the concentration easily changes during storage, etc. There were serious problems and further improvements were sought.

Although diarylimidazole compounds are widely used as hydrogen peroxide quantification reagents, there are almost no examples of adding them to photosensitive materials (see Patent Document 3). Although a technique using a diarylimidazole compound as a photothermographic material is disclosed in Patent Document 4, it is merely added as a reducing agent, and both sensitivity and density are insufficient.
JP 2002-169249 A JP 2002-236334 A Japanese Patent Publication No. 7-45477 US Pat. No. 3,985,565

  An object of the present invention is to solve the above-mentioned problems, and the highest density and sensitivity are high, the fog is small, the silver tone is a cool black tone, and the heat and light stability during image storage is excellent. Another object is to provide a photothermographic material.

  The above object of the present invention has been achieved by the following constitution.

(Claim 1)
The photothermographic material having an image forming layer containing a non-photosensitive organic silver salt, silver halide, silver ion reducing agent and binder on the support contains a compound represented by the following general formula (1). A photothermographic material characterized by the above.

(In the general formula (1), W represents a substituent other than a hydroxy group, a hydrogen atom or a halogen atom. R ₁ , R ₂ , R ₃ , R ₄ , R ₆ and R ₇ are a hydrogen atom, a substituent or a halogen atom. .X representing the atom is O, is .R ₅ representing S or N-R ₅ represents a hydrogen atom or a substituent.)
(Claim 2)
2. The heat according to claim 1, wherein in the general formula (1), W represents a hydrogen atom, an aliphatic group, an alkoxy group, an amino group, a sulfonamide group, an acylamino group, an acyloxy group, or a carbamoyloxy group. Development photosensitive material.

(Claim 3)
3. The photothermographic material according to claim 1, wherein in the general formula (1), at least one of R ₆ and R ₇ represents an aliphatic group, an aromatic group, or a heterocyclic group.

(Claim 4)
The photothermographic material according to claim 1, wherein, in the general formula (1), R ₁ and R ₂ represent an aliphatic group or an alkoxy group.

(Claim 5)
The photothermographic material according to claim 1, wherein the silver ion reducing agent is represented by the following general formula (R).

(In the general formula (R), R ₁₁ and R ₁₂ each independently represents a hydrogen atom, an aliphatic group or an aromatic group. R ₁₃ and R ₁₄ each independently represent a hydrogen atom, an aliphatic group, an aromatic group or Represents a heterocyclic group, Q represents a substitutable group on the benzene ring, and n represents an integer of 0 to 2. When Q is plural, each Q may be the same or different.
(Claim 6)
The addition ratio (molar ratio) of the compound represented by the general formula (1) and the silver ion reducing agent is 0.001 to 0.15, according to any one of claims 1 to 5. The photothermographic material according to the description.

  According to the present invention, it is possible to provide a photothermographic material having high maximum density and sensitivity, low fog, a cool black tone with good silver tone, and excellent heat and light stability during image storage. it can.

  As a result of diligent research, the inventor of the present invention relates to a photothermographic material having an image forming layer containing a non-photosensitive organic silver salt, a silver halide, a silver ion reducing agent and a binder on the support. ), The highest density and sensitivity, low fog, cool black tone with good silver tone, and heat development with excellent heat and light stability during image storage It has been found that a photosensitive material can be obtained.

  Hereinafter, the present invention will be described in detail.

<< Compound Represented by Formula (1) >>
The present invention is characterized by containing the compound represented by the general formula (1).

In the general formula (1), W represents a substituent other than a hydroxy group, a hydrogen atom, or a halogen atom. R ₁ , R ₂ , R ₃ , R ₄ , R ₆ and R ₇ represent a hydrogen atom, a substituent or a halogen atom. X represents O, S or N—R ₅ . R ₅ represents a hydrogen atom or a substituent.

  Examples of the substituent other than the hydroxy group represented by W include an aliphatic group, an aromatic group, a heterocyclic group, an alkoxy group, an aryloxy group, an acyloxy group, a carbamoyloxy group, an amino group, an acylamino group, a sulfonamide group, Cyano group, carboxyl group, sulfonyl group, nitro group, alkoxycarbonyl group, arylcarbonyl group, ureido group, thioureido group, alkylthio group, arylthio group, thioamide group, sulfamoyl group, sulfonylaminocarbonyl group, acylaminosulfonyl group, acylamino Specific examples include carbonyl group, sulfinylaminocarbonyl and the like.

  Examples of the aliphatic group include a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, and aralkyl group.

  Examples of aliphatic groups include methyl, ethyl, propyl, isopropyl, normal butyl, tert-butyl, pentyl, hexyl, decyl, dodecyl, pentadecyl, vinyl, allyl, Ethynyl, propargyl, cyclopropyl, cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclopentadienyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptynyl, cycloheptyl Dienyl group, cyclooctanyl group, cyclooctenyl group, cyclooctadienyl group, cyclooctatrienyl group, cyclononanyl group, cyclononenyl group, cyclononadienyl group, cyclononatrienyl cyclodecanyl group, cyclodecenyl group, cyclo Kajieniru group, and a cyclo tetradecatrienyl group.

  These groups may have a substituent or a halogen atom at an arbitrary position. Specific examples of the substituent include an alkyl group, a cyano group, an alkoxy group, a hydroxy group, an amino group, a carboxyl group, a carbooxy group, An aryl group, a heterocyclic ring, an aryloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, and an aryloxycarbonyloxy group are exemplified.

  The aromatic group represented by W may be a single ring or a condensed ring, and examples thereof include phenyl, naphthyl, anthracenyl, phenanthrenyl, naphthacenyl, and triphenylenyl. These rings may have various substituents or halogen atoms at any position, and as a preferable substituent, a linear or branched alkyl group (preferably having 1 to 20 carbon atoms such as methyl, ethyl, propyl, etc.). , Isopropyl, dodecyl, etc.), an alkoxy group (preferably having 1 to 20 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, dodecyloxy, etc.), an aliphatic acylamino group (preferably an alkyl group having 1 to 21 carbon atoms). For example, acetylamino group, heptylamino group, and the like, and aromatic acylamino groups.

  As the heterocyclic ring represented by W, aromatic heterocyclic groups such as pyridine group, quinoline group, isoquinoline group, imidazole group, pyrazole group, triazole group, oxazole group, thiazole group, oxadiazole group, thiadiazole group, tetrazole group, etc. And non-aromatic heterocyclic groups such as piperidino group, morpholino group, tetrahydrofuryl group, tetrahydrothienyl group and tetrahydropyranyl group. These groups may further have a substituent or a halogen atom, and examples of the substituent include the above-described substituents on the ring.

  Examples of the alkoxy group represented by W include methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group and the like.

  Examples of the aryloxy group represented by W include a phenoxy group and a naphthoxy group.

  Examples of the acyloxy group represented by W include an acetoxy group and a benzoyloxy group.

  Examples of the carbamoyloxy group represented by W include an N-methylcarbamoyloxy group, an N, N-dimethylcarbamoyloxy group, and an N, N-diethylcarbamoyloxy group.

  Examples of the amino group represented by W include an amino group, a dimethylamino group, and a diethylamino group.

  Examples of the acylamino group represented by W include an acetylamino group, a propionylamino group, and a benzoylamino group.

  Examples of the sulfonamide group represented by W include methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, and benzenesulfonamide group.

  Examples of the halogen atom represented by W include a chlorine atom, a bromine atom, an iodine atom, and a fluorine atom.

  Examples of the sulfonyl group represented by W include a methylsulfonyl group, an ethylsulfonyl group, a butylsulfonyl group, a cyclohexylsulfonyl group, a phenylsulfonyl group, and a 2-pyridylsulfonyl group.

  Examples of the alkoxycarbonyl group represented by W include an ethoxycarbonyl group and a butoxycarbonyl group.

  Examples of the arylcarbonyl group represented by W include a phenoxycarbonyl group and a naphthoxycarbonyl group.

  Examples of the ureido group represented by W include a ureido group, a 3-methylureido group, a 3-phenylureido group, and the like.

  Examples of the thioureido group represented by W include a thioureido group and a 3-methylthioureido group.

  Examples of the alkylthio group represented by W include methylthio and ethylthio groups.

  Examples of the arylthio group represented by W include a phenylthio group.

  Examples of the thioamide group represented by W include a thioacetamide group and a thiobenzoylamino group.

  Examples of the sulfamoyl group represented by W include a sulfamoyl group and an N, N-3-oxapentamethyleneaminosulfonyl group.

  Examples of the sulfonylaminocarbonyl group represented by W include methanesulfonylaminocarbonyl and ethanesulfonylaminocarbonyl groups.

  Examples of the acylaminosulfonyl group represented by W include acetamidosulfonyl and methoxyacetamidosulfonyl groups.

  Examples of the acylaminocarbonyl group represented by W include acetamidocarbonyl and methoxyacetamidocarbonyl groups.

  Examples of the sulfinylaminocarbonyl group represented by W include methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group and the like.

  When these groups can have a substituent or a halogen atom, they may have a substituent or a halogen atom at any position. Specific examples of the substituent include an alkyl group, a cyano group, and an alkoxy group. Group, hydroxy group, amino group, carboxyl group, carbooxy group, aryl group, heterocycle, aryloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group.

  W is preferably a hydrogen atom, aliphatic group, alkoxy group, amino group, sulfonamido group, acylamino group, acyloxy group or carbamoyloxy group, more preferably a hydrogen atom, amino group, sulfonamido group, acylamino group, An acyloxy group or a carbamoyloxy group;

In the general formula (1), R ₁ , R ₂ , R ₃ , R ₄ , R ₆ and R ₇ represent a hydrogen atom, a substituent or a halogen atom. X represents O, S or N—R ₅ . R ₅ represents a hydrogen atom or a substituent.

Examples of substituents represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₆ and R ₇ include alkyl groups (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group). Hexyl group, cyclohexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group etc.), alkenyl group, cycloalkenyl group, alkynyl group (propargyl group etc.), glycidyl group, acrylate group, methacrylate group, aryl group (phenyl group) Etc.), heterocyclic groups (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.) , Halogen atom (chlorine atom, bromine atom, iodine atom, fluorine atom Etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group etc.), alkoxycarbonyl group (methyloxycarbonyl) Group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexanesulfonamide group, Cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfur group) Nyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc.) ), Acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl) Group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), acylamino group (acetylamino group, benzoylamino) Group, methylureido group, etc.), amide group (acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenyl) Sulfonyl group, 2-pyridylsulfonyl group, etc.), sulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, phenylsulfonamide group, naphthylsulfonamide group, etc.), amino group (amino group, ethylamino group, dimethyl) Amino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group and the like. Further, these groups may be further substituted with these groups.

R ₁ and R ₂ are preferably an aliphatic group, an alkoxy group, an aryloxy group, more preferably an aliphatic group, an alkoxy group, still more preferably a secondary or tertiary alkyl group or an alkoxy group.

R ₃ and R ₄ are preferably a hydrogen atom, a sulfonamide group, a hydroxyl group, a carbamoyl group, and an acylamino group, more preferably a hydrogen atom, a sulfonamide group, a carbamoyl group, and an acylamino group.

R ₆ and R ₇ are preferably an aliphatic group, an aromatic group, a heterocyclic group, more preferably an alkyl group, an aromatic group, and still more preferably one of R ₆ and R ₇ is an aliphatic group, an aromatic group, It is a heterocyclic group.

X represents O, S or N—R ₅ . R ₅ represents a hydrogen atom or a substituent. Preferably X represents N—R ₅ .

R ₅ is preferably a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, or an acyl group, more preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 5 to 10 carbon atoms, or an acyl group. .

  The compound represented by the general formula (1) can be easily synthesized by a conventionally known method, for example, the method described in JP-B-7-45477.

  Next, although the specific example of a compound represented by General formula (1) is shown, this invention is not limited to these.

  The compound represented by the general formula (1) may be contained in at least one layer of the photosensitive layer of the photothermographic material or the non-photosensitive layer on the side of the photosensitive layer, and preferably contained in at least the photosensitive layer. is there.

  The compound represented by the general formula (1) can be added to the photosensitive layer or the non-photosensitive layer according to a known method. That is, it can be dissolved in an alcohol such as methanol or ethanol, a ketone such as methyl ethyl ketone or acetone, or a polar solvent such as dimethyl sulfoxide or dimethylformamide, and added to the coating solution for the photosensitive layer or the non-photosensitive layer. Further, fine particles of 1 μm or less can be dispersed and added in water or an organic solvent. Many techniques for fine particle dispersion are disclosed, but they can be dispersed according to these techniques.

<< Silver ion reducing agent represented by formula (R) >>
In the present invention, the silver ion reducing agent is preferably a bisphenol derivative represented by the general formula (R).

In the general formula (R), R ₁₁ and R ₁₂ each independently represents a hydrogen atom, an aliphatic group or an aromatic group. R ₁₃ and R1 ₄ are each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group. Q represents a substitutable group on the benzene ring, and n represents an integer of 0 to 2. When Q is plural, each Q may be the same or different.

In the general formula (R), R ₁₁ and R ₁₂ each independently represent a hydrogen atom, an aliphatic group, or an aromatic group.

Examples of the aliphatic group and aromatic group represented by R ₁₁ and R ₁₂ include the examples given as the aliphatic group and aromatic group represented by W in the general formula (1).

R ₁₁ is preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, still more preferably a methyl group, an ethyl group, an isopropyl group, It is a cyclohexyl group.

R ₁₂ is preferably a hydrogen atom.

R ₁₃ and R ₁₄ represent a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group.

Specific examples of the aliphatic group and aromatic group represented by R ₁₃ and R ₁₄ include the same groups as the examples of the aliphatic group and aromatic group represented by R ₁₁ and R ₁₂ .

Examples of the heterocyclic ring represented by R ₁₃ and R ₁₄ include pyridine group, quinoline group, isoquinoline group, imidazole group, pyrazole group, triazole group, oxazole group, thiazole group, oxadiazole group, thiadiazole group, and tetrazole group. Non-aromatic heterocyclic groups such as aromatic heterocyclic groups, piperidino groups, morpholino groups, tetrahydrofuryl groups, tetrahydrothienyl groups, tetrahydropyranyl groups and the like can be mentioned. These groups may further have a substituent, and examples of the substituent include the above-described substituents on the ring.

R ₁₃ is preferably an alkyl group or a cycloalkyl group, more preferably a secondary or tertiary alkyl group or a cycloalkyl group.

R ₁₄ is preferably an alkyl group, more preferably an alkyl group having 2 or more carbon atoms.

  Q represents a substitutable group on the benzene ring, specifically, an alkyl group having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, Cyclohexyl group, etc.), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkynyl group (propargyl group, etc.), glycidyl group, acrylate group, methacrylate group , Aryl groups (phenyl group, etc.), heterocyclic groups (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, pyrazolyl Group, tetrazolyl group, etc.), halogen atom (salt Atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group) Etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (phenyloxycarbonyl group etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, Butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyrate) Aminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc.), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylamino) Carbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group ( Acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), Amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group, etc. Can be mentioned. Further, these groups may be further substituted with these groups.

  n represents an integer of 0 to 2, and most preferably n is 0. When Q is plural, each Q may be the same or different.

  The compound represented by the general formula (R) is preferably obtained by dissolving or suspending 2 equivalents of phenol and 1 equivalent of aldehyde in the absence of solvent or in a suitable organic solvent, and adding a catalytic amount of acid or alkali, Preferably, it can be obtained in good yield by reacting at -20 to 180 ° C. for 0.5 to 60 hours.

  The organic solvent is preferably a hydrocarbon organic solvent, and specific examples include benzene, toluene, xylene, dichloromethane, chloroform and the like. More preferred are toluene and xylene. Furthermore, it is most preferable to make it react without a solvent from the point of a yield. Although any inorganic acid and organic acid can be used as the acid catalyst, concentrated hydrochloric acid, p-toluenesulfonic acid, and phosphoric acid are preferably used. As the alkali catalyst, caustic soda, caustic potash, triethylamine, DBU, sodium methylate is preferably used. The amount of catalyst is preferably 0.001 to 1.5 equivalents relative to the corresponding aldehyde. The reaction temperature is preferably 15 to 150 ° C., and the reaction time is preferably 3 to 20 hours.

  Next, although the specific example of a compound represented by general formula (R) is shown, this invention is not limited to these.

  The addition ratio (molar ratio) of the compound represented by the general formula (1) and the silver ion reducing agent in the present invention is preferably 0.001 to 0.15, more preferably 0.001 to 0.10. is there.

  The silver halide (also referred to as photosensitive silver halide grains or silver halide grains) used in the photothermographic material of the present invention (hereinafter also simply referred to as photosensitive material) will be described. The silver halide grains in the present invention can inherently absorb light as an intrinsic property of silver halide crystals, or artificially absorb visible light or infrared light by a physicochemical method. Physicochemical changes can occur in the silver halide crystal and / or on the crystal surface when absorbing light in any region within the light wavelength range from the ultraviolet light region to the infrared light region. The silver halide crystal grains produced by processing as described above.

(Silver halide grains)
The silver halide grains themselves according to the present invention are P.I. By Glafkides Chimie et Physique Photographic (published by Paul Montel, 1967), G. F. Duffin's Photographic Emission Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared as a silver halide grain emulsion using the method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al. That is, any method such as an acidic method, a neutral method, and an ammonia method may be used, and the formation of reacting a soluble silver salt and a soluble halogen salt may be any one of a one-side mixing method, a simultaneous mixing method, a combination thereof, and the like. Of these methods, the so-called controlled double jet method, in which silver halide grains are prepared while controlling the formation conditions, is preferred. The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

  Grain formation is usually divided into two stages, silver halide seed grain (nucleus) generation and grain growth, and these may be performed continuously at once, or the nucleus (seed grain) formation and grain growth are separated. The method of performing may be used. For the particle formation, a controlled double jet method in which particles are formed by controlling pAg, pH and the like is preferable because the particle shape and size can be controlled. For example, when performing a method of separating nucleation and grain growth, first, soluble silver salt and soluble halogen salt are uniformly and rapidly mixed in an aqueous gelatin solution to produce nuclei (seed grains) (nucleation process). Thereafter, silver halide grains are prepared by a grain growth process in which grains are grown while supplying a soluble silver salt and a soluble halogen salt under controlled pAg, pH and the like. After the formation of the grains, the desired salt halide emulsion can be obtained by removing unnecessary salts by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, or an electrodialysis method. it can.

  The silver halide grains according to the present invention preferably have a small average particle diameter in order to keep the white turbidity and color tone (yellowishness) after image formation low and to obtain good image quality, and the average particle diameter is 0.02 μm. As a value when particles less than the target of measurement are 0.035 μm or more and 0.055 μm or less are preferable. The grain size here means the length of the edge of the silver halide grain when the silver halide grain is a so-called normal crystal of a cube or octahedron. Further, when the silver halide grain is a tabular grain, it means the diameter when converted into a circular image having the same area as the projected area of the main surface.

  In the present invention, the silver halide grains are preferably monodispersed. The term “monodispersed” as used herein means that the coefficient of variation of the particle diameter obtained by the following formula is 30% or less. Preferably it is 20% or less, More preferably, it is 15% or less.

Coefficient of variation of particle size (%) = standard deviation of particle size / average value of particle size × 100
Examples of the shape of the silver halide grains include cubes, octahedrons, tetradecahedral grains, tabular grains, spherical grains, rod-like grains, and potato-like grains. Among these, cubic, octahedral, and tetrahedral Tabular silver halide grains are preferred.

  The average aspect ratio when using tabular silver halide grains is preferably 1.5 to 100, more preferably 2 to 50. These are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958, etc., and the desired tabular grains can be easily obtained. Further, grains having rounded corners of silver halide grains can be preferably used.

  There is no particular restriction on the crystal habit on the surface of the silver halide grain, but when using a spectral sensitizing dye having crystal habit (plane) selectivity in the adsorption reaction of the silver sensitizing dye on the surface of the silver halide grain. It is preferable to use silver halide grains having a relatively high proportion of crystal habits adapted to the selectivity. For example, when using a sensitizing dye that is selectively adsorbed on the crystal face of the Miller index [100], the ratio of the [100] face to the silver halide grain surface is preferably high, and this ratio is 50%. More preferably, it is 70% or more, particularly 80% or more. The ratio of the Miller index [100] plane is a T.K. based on the adsorption dependency of the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985).

  The silver halide grains used in the present invention are preferably prepared using low molecular weight gelatin having an average molecular weight of 50,000 or less at the time of grain formation, and particularly preferably used at the time of nucleation of silver halide grains. The low molecular weight gelatin has an average molecular weight of 50,000 or less, preferably 2000 to 40000, more preferably 5000 to 25000. The average molecular weight of gelatin can be measured by gel filtration chromatography. Low molecular weight gelatin can be hydrolyzed by adding gelatin-degrading enzyme to a commonly used gelatin aqueous solution with an average molecular weight of about 100,000, heating by adding acid or alkali, and heating under atmospheric pressure or pressure. Can be obtained by thermal decomposition, decomposition by ultrasonic irradiation, or a combination of these methods.

  The concentration of the dispersion medium at the time of nucleation is preferably 5% by mass or less, and it is more effective to carry out at a low concentration of 0.05 to 3.0% by mass.

  For the silver halide grains used in the present invention, it is preferable to use a polyethylene oxide compound represented by the following general formula when the grains are formed.

Formula _{YO (CH 2 CH 2 O)} m (CH (CH 3) CH 2 O) p (CH 2 CH 2 O) n Y
In the formula, Y represents a hydrogen atom, —SO ₃ M or —CO—B—COOM, and M represents a hydrogen atom, an alkali metal atom, an ammonium group or an ammonium group substituted with an alkyl group having 5 or less carbon atoms. , B represents a chain or cyclic group forming an organic dibasic acid. m and n each represents 0 to 50, and p represents 1 to 100.

  The polyethylene oxide compound represented by the above general formula is used to produce a photosensitive material, a step of producing a gelatin aqueous solution, a step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, and coating an emulsion on a support. For example, Japanese Patent Application Laid-Open No. 44-9497 discloses a technique for using an antifoaming agent as a defoaming agent for significant foaming when the emulsion raw material is stirred or moved. Are listed. The polyethylene oxide compound represented by the above general formula also functions as an antifoaming agent during nucleation.

  The polyethylene oxide compound represented by the above general formula is preferably used in an amount of 1% by mass or less, more preferably 0.01 to 0.1% by mass with respect to silver.

  The polyethylene oxide compound represented by the above general formula may be present at the time of nucleation and is preferably added in advance to the dispersion medium before nucleation, but may be added during nucleation or You may add and use for the silver salt aqueous solution and halide aqueous solution which are used at the time of formation. Preferably, it is used by adding 0.01 to 2.0% by mass to the halide aqueous solution or both aqueous solutions. Moreover, it is preferable to exist in the time over at least 50% of a nucleation process, More preferably, it exists in the time over 70% or more. The polyethylene oxide compound represented by the above general formula may be added as a powder or dissolved in a solvent such as methanol.

  The temperature at the time of nucleation is 5 to 60 ° C., preferably 15 to 50 ° C. Even if the temperature is constant, the temperature rising pattern (for example, the temperature at the start of nucleation is 25 ° C. It is preferable to control the temperature within the above temperature range even when the temperature is gradually raised and the temperature at the end of nucleation is 40 ° C.) and vice versa.

The concentration of the aqueous silver salt solution and aqueous halide solution used for nucleation is preferably 3.5 mol / liter or less, and more preferably in a low concentration range of 0.01 to 2.5 mol / liter. The addition rate of silver ions during nucleation is preferably 1.5 × 10 ^{−3 to} 3.0 × 10 ⁻¹ mol / min, more preferably 3.0 × 10 ^{−3 to} 8.0, per liter of the reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can be set in the range of 1.7 to 10, but the pH on the alkali side is preferably 2 to 6 in order to broaden the particle size distribution of nuclei to be formed. Moreover, pBr at the time of nucleation is about 0.05 to 3.0, preferably 1.0 to 2.5, and more preferably 1.5 to 2.0.

  The silver halide grains according to the present invention may be added to the photosensitive layer (also simply referred to as a photosensitive layer) by any method. At this time, the silver halide grains are added to a reducible silver source (aliphatic carboxylic acid silver salt). It is preferable to arrange them close to each other.

  The silver halide according to the present invention is prepared in advance, and this is added to a solution for preparing the aliphatic carboxylate silver salt grains. The silver halide preparation step and the aliphatic carboxylate silver salt grain preparation step However, as described in British Patent No. 1,447,454, when preparing aliphatic carboxylic acid silver salt particles, halogen components such as halide ions are used as fat. By coexisting with an aliphatic carboxylate silver salt-forming component and injecting silver ions therein, the aliphatic carboxylate silver salt particles can be produced almost simultaneously. It is also possible to prepare silver halide grains by converting an aliphatic carboxylic acid silver salt by allowing a halogen-containing compound to act on the aliphatic carboxylic acid silver salt. That is, a silver halide-forming component is allowed to act on a solution or dispersion of an aliphatic carboxylic acid silver salt prepared in advance, or a sheet material containing the aliphatic carboxylic acid silver salt, so that a part of the aliphatic carboxylic acid silver salt is removed. It can also be converted to photosensitive silver halide.

  Examples of silver halide grain forming components include inorganic halogen compounds, onium halides, halogenated hydrocarbons, N-halogen compounds, and other halogen-containing compounds. Specific examples thereof are described in US Pat. No. 4,009,039. No. 3,457,075, No. 4,003,749, British Patent No. 1,498,956 and JP-A Nos. 53-27027 and 53-25420. Inorganic halides such as ammonium halides, for example, onium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, trimethylbenzylammonium bromide, such as iodoform, bromoform, carbon tetrachloride, 2-bromo-2-methyl Halogenated hydrocarbons such as propane N-halogen compounds such as N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, and others, such as triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, dichloro There are benzophenone and the like. Thus, silver halide can also be prepared by converting a part or all of silver in the organic acid silver salt into silver halide by the reaction of the organic acid silver and the halogen ion. Moreover, you may use together the silver halide grain manufactured by converting a part of aliphatic carboxylic acid silver salt into the silver halide prepared separately.

  These silver halide grains are separately prepared silver halide grains, 0.001 to 0.7 mol per 1 mol of aliphatic carboxylic acid silver salt, and silver halide grains obtained by conversion of aliphatic carboxylic acid silver salt. Preferably 0.03-0.5 mol is used.

  The silver halide grains according to the present invention preferably contain ions of transition metals belonging to Groups 6 to 11 of the periodic table. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable. These may be used alone or in combination of two or more of the same or different metal complexes.

For these metal ions, a metal salt may be introduced as it is into silver halide, but can be introduced into silver halide in the form of a metal complex or complex ion. The preferable content is in the range of 1 × 10 ⁻⁹ to 1 × 10 ⁻² mol, and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ with ^respect to 1 mol of silver. In the present invention, the transition metal complex or complex ion is preferably represented by the following general formula.

General formula [ML ₆ ] ^m
In the formula, M represents a transition metal selected from Group 6 to 11 elements of the periodic table, L represents a ligand, and m represents 0,-, 2-, 3-, or 4-. Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aco. A ligand, nitrosyl, thionitrosyl and the like can be mentioned, and ako, nitrosyl, thionitrosyl and the like are preferable. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

  The compounds providing these metal ions or complex ions are preferably added during silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening , May be added at any stage before or after chemical sensitization, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Preferably, it is added at the stage of nucleation. In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in JP-A Nos. 167545, 4-76534, 6-110146, 5-273683, etc., the particles can be contained with a distribution.

  These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound is dissolved together with NaCl and KCl is added to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or a silver salt solution and a halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a method of simultaneous mixing of three solutions, a method of adding an aqueous solution of a required amount of a metal compound to a reaction vessel during grain formation, or a preparation of silver halide There is a method of adding and dissolving another silver halide grain which has been previously doped with metal ions or complex ions. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution. When added to the particle surface, a necessary amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or after physical ripening, or at the time of chemical ripening.

  Separately prepared silver halide grains can be desalted by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, or an electrodialysis method, but can also be used without desalting.

(Non-photosensitive organic silver salt)
The non-photosensitive organic silver salt according to the present invention is a reducible silver source, is a salt of an organic acid containing silver ions, and is non-photosensitive. As the organic acid used in the present invention, aliphatic carboxylic acid, carbocyclic carboxylic acid, heterocyclic carboxylic acid, heterocyclic compound and the like are used.

  Examples of non-photosensitive organic acid silver salts according to the present invention are described in Research Disclosure Nos. 17029 and 29963, and silver salts of aliphatic carboxylic acids (for example, gallic acid, oxalic acid, behenic acid, arachidic acid, Silver salts of stearic acid, palmitic acid, lauric acid, etc.); silver carboxyalkylthiourea salts (for example, 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, etc. ); A silver complex of a polymerization reaction product of an aldehyde and a hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.) and hydroxy-substituted aromatic carboxylic acids (for example, salicylic acid, benzoic acid, 3, 5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc. A silver complex of a polymerization reaction product with thione, a silver salt or a complex of thiones (for example, 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione, and 3-carboxymethyl- 4-thiazoline-2-thione), imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, nitrogen selected from 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole Examples include acid and silver complexes or salts; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides.

  Among the organic silver salts described above, a silver salt of an aliphatic carboxylic acid is preferably used, and a silver salt of an aliphatic carboxylic acid having 10 to 30 carbon atoms, more preferably 15 to 25 carbon atoms. Examples of suitable silver salts include the following.

  Silver salts such as gallic acid, succinic acid, behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid. Among these, preferable silver salts include silver behenate, silver arachidate, and silver stearate. In the present invention, it is preferable that two or more types of aliphatic carboxylic acid silver salts are mixed in order to improve developability and form a silver image having a high density and a high contrast. For example, two or more types of aliphatic carboxylic acid salts are used. It is preferable to prepare by mixing a silver ion solution with an acid mixture.

  The aliphatic carboxylic acid silver salt compound can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and is described in Japanese Patent Application Laid-Open No. 9-127643. The controlled double jet method as described above is preferably used. For example, an alkali metal salt (for example, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to produce an organic acid alkali metal salt soap (for example, sodium behenate, sodium arachidate, etc.), then controlled double jet According to the method, the soap and silver nitrate are mixed to produce an aliphatic carboxylic acid silver salt crystal. At that time, silver halide grains may be mixed.

  In the aliphatic carboxylic acid silver salt according to the present invention, the average equivalent circle diameter can be adjusted in the range of 0.05 to 0.8 μm from the viewpoint of improving the transparency of the image after heat development and improving the image storage stability. Preferably, silver ions are appropriately supplied during heat development, and the average thickness is preferably adjusted to 0.005 to 0.07 μm, particularly preferably from the viewpoint of improving the storage stability of the obtained image. The average equivalent circle diameter is 0.2 to 0.5 μm and the average thickness is adjusted to 0.01 to 0.05 μm.

  To obtain the average equivalent circle diameter, the dispersed aliphatic carboxylic acid silver salt is diluted and dispersed on a grid with a carbon support film, and the transmission electron microscope (manufactured by JEOL Ltd., 2000FX type) is directly increased to 5000 times magnification. I took a picture. The negative is captured as a digital image with a scanner, and 300 or more particle sizes (equivalent circle diameter) are measured using appropriate image processing software, and the average particle size is calculated.

  The average thickness is calculated by a method using a TEM (transmission electron microscope) as shown below.

  First, the photosensitive layer coated on the support is attached to an appropriate holder with an adhesive, and an ultrathin slice having a thickness of 0.1 to 0.2 μm is produced using a diamond knife in a direction perpendicular to the support surface. . The prepared ultra-thin slice was supported on a copper mesh, transferred onto a carbon film hydrophilized by glow discharge, and cooled to −130 ° C. or lower with liquid nitrogen, using a TEM, at a magnification of 5,000 to 40 times. A bright field image is observed at a magnification of 1,000,000, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like. At this time, it is preferable to appropriately select a portion where the section is not torn or slack as the field of view to be observed.

  As the carbon film, it is preferable to use a film supported by an organic film such as ultra-thin collodion or formbar, and more preferably, it is formed on a rock salt substrate and obtained by dissolving and removing the substrate, or the organic film is organic It is a carbon-only film obtained by solvent and ion etching. The TEM acceleration voltage is preferably 80 to 400 kV, particularly preferably 80 to 200 kV.

  In addition, for details of electron microscope observation techniques and sample preparation techniques, see “The Electron Microscopy Society of Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Electron Microscopy Society of Kanto Branch / Electron Microscope Biological Sample Preparation” Law "(Maruzen) can be used as a reference.

  A TEM image recorded on an appropriate medium is preferably decomposed into at least 1024 × 1024 pixels, preferably 2048 × 2048 pixels or more, and subjected to image processing by a computer. In order to perform image processing, it is preferable that an analog image recorded on a film is converted into a digital image by a scanner or the like, and shading correction, contrast / edge enhancement, etc. are performed as necessary. Thereafter, a histogram is prepared, and a portion corresponding to the aliphatic carboxylate silver is extracted by binarization processing.

  300 or more of the extracted aliphatic carboxylic acid silver salt particles are manually measured with appropriate software to obtain an average value.

  The method for obtaining the aliphatic carboxylic acid silver salt particles having the above-mentioned shape is not particularly limited, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap, etc. It is effective to keep the temperature good, to optimize the ratio of the organic acid to the soap, and the ratio of the silver nitrate that reacts with the soap.

  Tabular aliphatic carboxylic acid silver salt particles used in the present invention (aliphatic carboxylic acid silver salt particles having an average equivalent circle diameter of 0.05 to 0.8 μm and an average thickness of 0.005 to 0.07 μm) Is preferably preliminarily dispersed together with a binder, a surfactant or the like, if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. For the preliminary dispersion, a general stirrer such as an anchor type or a propeller type, a high-speed rotating centrifugal radiation type stirrer (dissolver), or a high-speed rotating shear type stirrer (homomixer) can be used.

  In addition, as the media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill that is a medium stirring mill, an attritor, and other basket mills can be used, and a wall is used as a high-pressure homogenizer. Various types such as a type that collides with a plug or the like, a type that collides liquids at a high speed after dividing the liquid into a plurality of types, and a type that passes through a thin orifice can be used.

Examples of ceramics used for the ceramic beads used when dispersing the media include Al ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , MgO, ZrO, BeO, Cr ₂ O ₃ , SiO ₂ , SiO ₂ —Al ₂ O ₃ , Cr. ₂ O ₃ —MgO, MgO—CaO, MgO—C, MgO—Al ₂ O ₃ (spinel), SiC, TiO ₂ , K ₂ O, Na ₂ O, BaO, PbO, B ₂ O ₃ , SrTiO ₃ (titanium) _{strontium), BeAl 2 O 4, Y} 3 Al 5 O 12, ZrO 2 -Y 2 O 3 ( cubic _{zirconia), 3BeO-Al 2 O 3} -6SiO 2 ( synthesis emerald), C (diamond), Si ₂ O—nH ₂ O, ticker silicon, yttrium-stabilized zirconia, zirconia-reinforced alumina, and the like are preferable. Yttrium-stabilized zirconia and zirconia-reinforced alumina (ceramics containing these zirconia are hereinafter abbreviated as zirconia) are particularly preferably used because of the low generation of impurities due to friction with beads and dispersers during dispersion.

  In the apparatus used for dispersing the tabular aliphatic carboxylic acid silver salt particles used in the present invention, zirconia, alumina, silicon nitride, boron nitride, etc. are used as the material of the member in contact with the aliphatic carboxylic acid silver salt particles. These ceramics or diamond are preferably used, and zirconia is particularly preferable. When the above dispersion is performed, the binder concentration is preferably added in an amount of 0.1 to 10% by mass of silver aliphatic carboxylate, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion through the main dispersion. As preferable operating conditions for the present dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, the preferable operating conditions are 29.42 to 98.06 MPa, and the number of operations is preferably 2 times or more. Moreover, when using a media dispersion machine as a dispersion | distribution means, a peripheral speed is mentioned as 6-13 m / sec as preferable conditions.

  In the present invention, the compound that functions as a crystal growth inhibitor or dispersant for the aliphatic carboxylate silver particles refers to a silver aliphatic carboxylate under the conditions in which the compound coexists in the production process of the aliphatic carboxylate particles. A compound having a function and an effect of reducing the particle size or monodispersing than when it is produced under conditions that do not coexist. Specific examples include monohydric alcohols having 10 or less carbon atoms, preferably secondary alcohols, tertiary alcohols, glycols such as ethylene glycol and propylene glycol, polyethers such as polyethylene glycol, and glycerin. A preferable addition amount is 10 to 200% by mass with respect to the aliphatic carboxylate silver.

  On the other hand, branched aliphatic carboxylic acids containing isomers such as isoheptanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, isopalmitic acid, isostearic acid, isoarachidic acid, isobehenic acid and isohexaconic acid are also preferred. In this case, a preferable side chain includes an alkyl group or an alkenyl group having 4 or less carbon atoms. In addition, aliphatic unsaturated carboxylic acids such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, morotic acid, eicosenoic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, and ceracolonic acid It is done. A preferable addition amount is 0.5 to 10 mol% of the aliphatic carboxylate silver.

  Glycosides such as glucoside, galactoside and fructoside, trehalose type disaccharides such as trehalose and sucrose, polysaccharides such as glycogen, dextrin, dextran and alginic acid, cellosolves such as methyl cellosolve and ethyl cellosolve, sorbitan, sorbit, ethyl acetate and acetic acid Water-soluble organic solvents such as methyl and dimethylformamide, water-soluble polymers such as polyvinyl alcohol, polyacrylic acid, acrylic acid copolymer, maleic acid copolymer, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone and gelatin Are also preferred compounds. A preferable addition amount is 0.1 to 20% by mass with respect to aliphatic silver carboxylate.

  Alcohols having 10 or less carbon atoms, preferably secondary alcohols and tertiary alcohols, are reduced in viscosity by increasing the solubility of sodium aliphatic carboxylate in the preparation step, and monodispersed and small by increasing the stirring efficiency. Grain size. Branched aliphatic carboxylic acids and aliphatic unsaturated carboxylic acids have higher steric hindrance than the main component linear aliphatic carboxylic acid silver when crystallization of the aliphatic carboxylic acid silver, and the disorder of the crystal lattice is large. Therefore, large crystals are not generated, and as a result, the particle size is reduced.

  As described above, compared to conventional silver halide photographic light-sensitive materials, the biggest difference in the composition of heat-developable light-sensitive materials is that the latter materials are fogged and printed regardless of before and after the development process. That is, it contains a large amount of silver halide, organic silver salt, and reducing agent that can cause out silver (baked out silver). For this reason, in order to maintain the storage stability not only before development but also after development, it is essential for the photothermographic material to have high fog prevention and image stabilization technology. In addition to aromatic heterocyclic compounds that suppress oxidization, mercury compounds such as mercury acetate having the function of oxidizing and extinguishing fog nuclei have been used as very effective storage stabilizers. Use was a problem in terms of safety and environmental conservation.

(Anti-fogging agent, image stabilizer)
The antifogging and image stabilizer used in the photothermographic material of the present invention will be described below.

  In the photothermographic material of the present invention, as will be described later, bisphenols are mainly used as the reducing agent. Therefore, reduction is achieved by generating active species capable of extracting these hydrogens. It is preferable that a compound capable of inactivating the agent is contained. A colorless photo-oxidizable substance is preferably a compound capable of generating free radicals as reactive active species during exposure.

  Accordingly, any compound having these functions may be used, but an organic free radical composed of a plurality of atoms is preferred. A compound having any structure may be used as long as it has such a function and does not cause any particular adverse effect on the photothermographic material.

  In addition, these free radical-generating compounds are carbocyclic or heterocyclic in order to give the generated free radicals stable enough to be in contact with the reducing agent for a sufficient time to inactivate. Those having the following aromatic group are preferred.

  Representative examples of these compounds include biimidazolyl compounds and iodonium compounds listed below.

  As the biimidazolyl compound, a compound represented by the following general formula [1] is preferably used.

In the formula, each of R ¹ , R ² and R ³ (same or different) is an alkyl group (for example, methyl group, ethyl group, hexyl group, etc.), alkenyl group (for example, vinyl group, allyl group), alkoxy group (For example, methoxy group, ethoxy group, octyloxy group), aryl group (for example, phenyl group, naphthyl group, tolyl group), hydroxyl group, halogen atom, aryloxy group (for example, phenoxy group), alkylthio group (for example, Methylthio group, butylthio group), arylthio group (for example, phenylthio group), acyl group (for example, acetyl group, propionyl group, butyryl group, valeryl group), sulfonyl group (for example, methylsulfonyl group, phenylsulfonyl group, etc.), acylamino Group, sulfonylamino group, acyloxy group (for example, acetoxy group, Nzokishi group), showing a carboxyl group, a cyano group, a sulfo group or an amino group. Among these, more preferred substituents are an aryl group, an alkenyl group, a cyano group, and the like.

  The above-mentioned biimidazolyl compound can be produced by the production methods described in US Pat. No. 3,734,733 and British Patent No. 1,271,177 and methods according thereto. As a preferable specific example, the compound example described in Unexamined-Japanese-Patent No. 2000-321711 can be mentioned, for example.

  Similarly, a suitable compound includes an iodonium compound represented by the following general formula [2].

Wherein Q ₁ includes the atoms necessary to complete a 5, 6 or 7 membered ring, and the required atoms are selected from carbon atoms, nitrogen atoms, oxygen atoms and sulfur atoms. Each of R ¹ , R ² and R ³ (same or different) is a hydrogen atom, an alkyl group (eg, methyl group, ethyl group, hexyl group, etc.), an alkenyl group (eg, vinyl group, allyl group, etc.), alkoxy Group (for example, methoxy group, ethoxy group, octyloxy group, etc.), aryl group (for example, phenyl group, naphthyl group, tolyl group, etc.), hydroxyl group, halogen atom, aryloxy group (for example, phenoxy group), alkylthio group (For example, methylthio group, butylthio group), arylthio group (for example, phenylthio group), acyl group (for example, acetyl group, propionyl group, butyryl group, valeryl group, etc.), sulfonyl group (for example, methylsulfonyl group, phenylsulfonyl group) Etc.), acylamino group, sulfonylamino group, acyloxy group (for example, Butoxy group, benzoxy group), showing a carboxyl group, a cyano group, a sulfo group and an amino group. Among these, more preferred substituents are an aryl group, an alkenyl group, and a cyano group.

R ⁴ represents a carboxylate group such as acetate, benzoate or trifluoroacetate and O 2 ⁻ . W represents 0 or 1.

X ⁻ is an anionic counter ion, and preferred examples are CH ₃ CO ₂ ⁻ , CH ₃ SO ₃ ⁻ and PF ₆ ⁻ .

When R ³ is a sulfo group or a carboxyl group, W is 0 and R ⁴ is O ⁻ .

In addition, any of R ¹ , R ² and R ³ may be bonded to each other to form a ring.

  Among these, a particularly preferred compound is a compound represented by the following general formula [3].

^{Wherein, R 1, R 2, R} 3, R 4, X - and W, are as defined in the general formula (2), Y is a carbon atom; or represents (-CH = benzene ring) or nitrogen, Represents an atom (-N =; pyridine ring).

  The above iodonium compounds are described in Org. Syn. , 1961 and "Advanced Organic Chemistry by Fieser" (Reinhold, NY, 1961) and a method analogous thereto.

  As a preferable specific example, the compound example described in Unexamined-Japanese-Patent No. 2000-321711 can be mentioned, for example.

The amount of the compound represented by the general formulas [1] and [2] is 10 ⁻³ to 10 ⁻¹ mol / m ² , preferably 5 × 10 ^{−3 to} 5 × 10 ⁻² mol / m ^2. It is. The compound can be contained in any constituent layer in the light-sensitive material of the present invention, but is preferably contained in the vicinity of the reducing agent.

  Further, as a compound that inactivates the reducing agent and prevents the reducing agent from reducing the aliphatic carboxylic acid silver salt to silver, a compound in which the reactive species is not a halogen atom is preferable, but a compound that releases a halogen atom as an active species is also available. Can be used in combination with a compound that releases an active species that is not a halogen atom. Many compounds capable of releasing a halogen atom as an active species are known, and a good effect can be obtained by the combined use.

  Specific examples of the compound that generates these active halogen atoms include compounds represented by the following general formula [4].

In the formula, Q ₂ represents an aryl group or a heterocyclic group. X ₁ , X ₂ and X ₃ each represent a hydrogen atom, a halogen atom, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or an aryl group, at least one of which is a halogen atom. Y represents —C (═O) —, —SO— or —SO ₂ —.

The aryl group represented by Q ₂ may be monocyclic or condensed, and is preferably a monocyclic or bicyclic aryl group having 6 to 30 carbon atoms (for example, a phenyl group, a naphthyl group, etc.) More preferred are a phenyl group and a naphthyl group, and even more preferred is a phenyl group.

The heterocyclic group represented by Q ₂ is a 3 to 10-membered saturated or unsaturated heterocyclic group containing at least one atom of N, O or S, and these may be monocyclic, Furthermore, you may form a condensed ring with another ring.

  The heterocyclic group is preferably a 5- to 6-membered unsaturated heterocyclic group which may have a condensed ring, more preferably a 5- to 6-membered aromatic heterocyclic ring which may have a condensed ring. It is a group. More preferably, it is a 5- or 6-membered aromatic heterocyclic group which may have a condensed ring containing a nitrogen atom, and particularly preferably 5 which may have a condensed ring containing 1 to 4 nitrogen atoms. A 6-membered aromatic heterocyclic group. As the heterocyclic ring in such a heterocyclic group, preferably imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline Cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, indolenine, tetrazaindene, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, Triazine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinoaline Zolin, cinnoline, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, tetrazaindene, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole, quinoline, phthalazine, naphthyridine, Quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, benzimidazole, and benzothiazole are preferable, and pyridine, thiadiazole, quinoline, and benzothiazole are particularly preferable.

The aryl group and heterocyclic group represented by Q ₂ may have a substituent in addition to —Y—C (X ₁ ) (X ₂ ) (X ₃ ), and the substituent is preferably an alkyl group, Alkenyl group, aryl group, alkoxy group, aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl Group, carbamoyl group, sulfonyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, sulfo group, carboxyl group, nitro group, heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryl Oxy group, acyl group, acylamino group, alkoxycarbonylamino , Aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, nitro group, heterocyclic group, more preferably alkyl group, aryl group, alkoxy group Group, aryloxy group, acyl group, acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, halogen atom, cyano group, nitro group, heterocyclic group, particularly preferably alkyl group, aryl group, halogen atom .

The substituents represented by X ₁ , X ₂ and X ₃ are each preferably a halogen atom, a haloalkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group or a heterocyclic group. Is more preferably a halogen atom, haloalkyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, sulfonyl group (alkylsulfonyl group, arylsulfonyl group), more preferably a halogen atom or trihalomethyl group, Particularly preferred is a halogen atom. Of the halogen atoms, preferred are a chlorine atom, a bromine atom and an iodine atom, more preferred are a chlorine atom and a bromine atom, and particularly preferred is a bromine atom.

Y is, -C (= O) -, - SO- or, -SO ₂ - represents a, among them preferably used is, -SO ₂ - is.

  The amount of these compounds added is preferably in a range where the increase in printout silver due to the formation of silver halide does not become a problem, and is preferably at most 150% by mass or less, more preferably not more than 150% by mass relative to the compound that does not generate active halogen radicals Is preferably 100% by mass or less.

  In addition to the above compounds, the photothermographic material of the present invention may contain a compound conventionally known as an antifoggant, but generates a reactive species similar to the above compound. Even a compound that can be used may be a compound having a different antifogging mechanism. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. No. 3,874,946, No. 4,756,999, JP-A-9-288328 and JP-A-9-90550. Further, other antifoggants include compounds disclosed in US Pat. No. 5,028,523 and European Patents 600,587, 605,981, and 631,176. .

  In the present invention, a known reducing agent can be used as the reducing agent. Preferably, it is a bisphenol-type reducing agent represented by the general formula (R).

  The amount of the silver ion reducing agent used in the photothermographic material of the present invention varies depending on the type of organic silver salt, reducing agent, and other additives, but is generally 0.05 per mole of organic silver salt. -10 mol, preferably 0.1-3 mol is appropriate. Within this range, two or more silver ion reducing agents according to the present invention may be used in combination. In the present invention, it may be preferable that the reducing agent is added to and mixed with a photosensitive emulsion solution composed of silver halide and organic silver salt grains and a solvent immediately before coating because the variation in photographic performance due to stagnation time is small.

  The silver halide according to the present invention can be chemically sensitized. For example, by the method described in Japanese Patent Application Laid-Open Nos. 2001-249428 and 2001-249426, a chemical increase is achieved by using a compound that releases chalcogen such as sulfur or a noble metal compound that releases noble metal ions such as gold ions. Forms and gives a sensitive center (chemical sensitization nucleus) It is preferably chemically sensitized with an organic sensitizer containing chalcogen atoms shown below.

  These organic sensitizers containing chalcogen atoms are preferably compounds having groups capable of adsorbing to silver halide and unstable chalcogen atom sites.

  As these organic sensitizers, organic sensitizers having various structures disclosed in JP-A-60-150046, JP-A-4-109240, JP-A-11-218874, and the like can be used. Of these, at least one compound having a structure in which a chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond is preferable.

The amount of chalcogen compound used as the organic sensitizer varies depending on the chalcogen compound used, the silver halide grains, the reaction environment for chemical sensitization, etc., but is 10 ⁻⁸ to 10 ⁻ per mol of silver halide. ² mol is preferred, more preferably 10 ⁻⁷ to 10 ⁻³ mol. The chemical sensitization environment is not particularly limited, but can oxidize silver nuclei in the presence of a compound capable of annihilating or reducing the size of silver chalcogenide or silver nuclei on silver halide grains. In the presence of an oxidizing agent, it is preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom. As the sensitization condition, pAg is preferably 6 to 11, more preferably 7 to 10. Yes, the pH is preferably from 4 to 10, more preferably from 5 to 8, and the temperature is preferably sensitized at 30 ° C. or lower.

  Therefore, in the photothermographic material of the present invention, the silver halide is 30 ° C. or less using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei on the grain. It is preferable to use a photosensitive emulsion that has been chemically sensitized and mixed with an aliphatic carboxylic acid silver salt, dispersed, dehydrated and dried.

  Further, chemical sensitization using these organic sensitizers is preferably carried out in the presence of a heteroatom-containing compound having adsorptivity for spectral sensitizing dyes or silver halide grains. By performing chemical sensitization in the presence of a compound having an adsorptivity to silver halide, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved. Although the spectral sensitizing dye will be described later, preferred examples of the heteroatom-containing compound having adsorptivity to silver halide include nitrogen-containing heterocyclic compounds described in JP-A-3-24537. In the nitrogen-containing heterocyclic compound, the heterocyclic ring includes pyrazole ring, pyrimidine ring, 1,2,4-triazole ring, 1,2,3-triazole ring, 1,3,4-thiadiazole ring, 1,2,3- Thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,3,4-tetrazole ring, pyridazine ring, 1,2,3-triazine ring, Examples thereof include three bonded rings such as a triazolotriazole ring, a diazaindene ring, a triazaindene ring, and a pentaazaindene ring. A heterocyclic ring in which a monocyclic heterocyclic ring and an aromatic ring are condensed, for example, a phthalazine ring, a benzimidazole ring, an indazole ring, a benzothiazole ring, or the like can also be applied.

  Among these, an azaindene ring is preferable, and an azaindene compound having a hydroxyl group as a substituent, for example, hydroxytriazaindene, tetrahydroxyazaindene, hydroxypentaazaindene compound and the like are more preferable.

  The heterocyclic ring may have a substituent other than the hydroxyl group. Examples of the substituent include an alkyl group, a substituted alkyl group, an alkylthio group, an amino group, a hydroxyamino group, an alkylamino group, a dialkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, a halogen atom, and a cyano group. May be.

The amount of the heterocyclic compound added varies over a wide range depending on the size, composition and other conditions of the silver halide grains, but the approximate amount is 10 ⁻⁶ to 1 mole per mole of silver halide. And preferably in the range of 10 ^{−4 to} 10−1 mol.

  The silver halide according to the present invention can be subjected to noble metal sensitization using a compound that releases noble metal ions such as gold ions. For example, a chloroaurate or an organic gold compound can be used as a gold sensitizer.

  In addition to the above sensitization methods, reduction sensitization methods and the like can also be used. Examples of reduction sensitization shell-like compounds include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, and borane. A compound, a silane compound, a polyamine compound, or the like can be used. Further, reduction sensitization can be performed by ripening the emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower.

  The silver halide subjected to chemical sensitization may be formed in the presence of an organic silver salt, formed in the absence of an organic silver salt, or a mixture of both. .

  The silver halide according to the present invention is preferably subjected to spectral sensitization by adsorbing a spectral sensitizing dye. As spectral sensitizing dyes, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes, and the like can be used. For example, JP-A-63-159841, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, JP-A-63-15245, US Pat. No. 4,639,414, No. 4,740,455, No. 4,741,966, No. 4,751,175, No. 4,835,096 can be used.

  Useful sensitizing dyes used in the present invention are described in, for example, the literature described or cited in Section RD17643IV-A (December 1978, p.23), Section 18431X (August 1978, p.437). ing. In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light sources of various laser imagers and scanners. For example, compounds described in JP-A Nos. 9-34078, 9-54409, and 9-80679 are preferably used.

  Useful cyanine dyes are cyanine dyes having basic nuclei such as thiazoline nucleus, oxazoline nucleus, pyrroline nucleus, pyridine nucleus, oxazole nucleus, thiazole nucleus, selenazole nucleus and imidazole nucleus. Useful merocyanine dyes are preferably acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus in addition to the basic nuclei described above. Including.

  In the present invention, a sensitizing dye having spectral sensitivity particularly in the infrared can also be used. Examples of infrared spectral sensitizing dyes preferably used include infrared spectral sensitization disclosed in US Pat. Nos. 4,536,473, 4,515,888, 4,959,294, and the like. Examples include dyes.

  As the infrared spectral sensitizing dye, a long-chain polymethine dye characterized in that a sulfinyl group is substituted on the benzene ring of the benzoazole ring is particularly preferable.

  The above-mentioned infrared sensitizing dyes are described in, for example, HM Hammer, The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanine Dies and Related Compounds, published by A. Weissberger ed. It can be synthesized with reference to the method.

  These infrared sensitizing dyes may be added at any time after the preparation of the silver halide. For example, silver halide grains or silver halide grains / in a so-called solid dispersion state added to a solvent or dispersed in the form of fine particles. It can be added to a photosensitive emulsion containing aliphatic carboxylic acid silver salt grains. Similarly to the heteroatom-containing compound having adsorptivity to the silver halide grains, chemical sensitization can be performed after being added to and adsorbed to the silver halide grains prior to chemical sensitization. Thus, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved.

  In the present invention, the above-mentioned spectral sensitizing dyes may be used alone or in combination, and the combination of sensitizing dyes is often used for the purpose of supersensitization.

  The emulsion containing the silver halide and the aliphatic carboxylic acid silver salt used in the photothermographic material of the present invention substantially absorbs a dye having no spectral sensitizing action or visible light itself together with the sensitizing dye. A substance that does not exhibit a supersensitization effect may be included in the emulsion, whereby the silver halide grains may be supersensitized.

  Useful sensitizing dyes, combinations of dyes exhibiting supersensitization, and substances exhibiting supersensitization are described in RD17643 (issued in December, 1978), page 23, Section J, or Japanese Patent Publication No. 9-25500, 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. Examples of supersensitizers include heteroaromatic mercapto represented by the following. Compounds or mercapto derivative compounds are preferred.

Ar-SM
In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine , Purine, quinoline, or quinazoline. However, other heteroaromatic rings are also included.

  In addition, a mercapto derivative compound which substantially forms the mercapto compound when contained in a dispersion of an aliphatic carboxylic acid silver salt and / or a silver halide grain emulsion is also included. In particular, mercapto derivative compounds represented below are preferred examples.

Ar-SS-Ar
Ar in the formula has the same meaning as in the case of the mercapto compound represented above.

  The heteroaromatic ring is, for example, a halogen atom (for example, Cl, Br, I), a hydroxyl group, an amino group, a carboxyl group, an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms). And a substituent selected from the group consisting of an alkoxy group (for example, one having one or more carbon atoms, preferably 1 to 4 carbon atoms).

  In addition to the supersensitizer described above, compounds represented by the following general formula [5] and macrocycles disclosed in Japanese Patent Application No. 2000-70296 can be used as supersensitizers.

In the formula, H ₃₁ Ar represents an aromatic hydrocarbon group or an aromatic heterocyclic group, T ₃₁ represents a divalent linking group or linking group composed of an aliphatic hydrocarbon group, and J ₃₁ represents an oxygen atom or a sulfur atom. Alternatively, it represents a divalent linking group or linking group containing one or more nitrogen atoms. Ra, Rb, Rc and Rd each represent a hydrogen atom, an acyl group, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group, or between Ra and Rb, Rc and Rd, Ra and Rc, or Rb and Rd. It can combine to form a nitrogen-containing heterocyclic group. M31 represents an ion necessary to cancel the charge in the molecule, and k31 represents the number of ions required to cancel the charge in the molecule.

In the general formula [5], the divalent linking group composed of the aliphatic hydrocarbon group represented by T ₃₁ is a linear, branched or cyclic alkylene group (preferably having 1 to 20 carbon atoms, more preferably 1). -16, more preferably 1-12), alkenyl group (preferably 2-20 carbon atoms, more preferably 2-16, more preferably 2-12), alkynyl group (preferably 2-20 carbon atoms, more preferably). 2 to 16 and more preferably 2 to 12), which may have a substituent, for example, as an aliphatic hydrocarbon group, a linear, branched or cyclic alkyl group (preferably having a carbon number of 1 to 20, more preferably 1-16, more preferably 1-12, alkenyl group (preferably 2-20 carbon atoms, more preferably 2-16, more preferably 2-12), alkynyl group (preferably The aryl group may be a monocyclic or condensed aryl group having 6 to 20 carbon atoms (e.g., phenyl, naphthyl). The heterocyclic group is preferably a 3- to 10-membered saturated or unsaturated heterocyclic group (for example, 2-thiazolyl, 1-piperazinyl, 2-pyridyl, 3-pyridyl, 2-furyl, 2-thienyl group, 2-benzimidazolyl group, carbazolyl group, etc.), and the heterocycle in these groups may be a single ring or may form a condensed ring with another ring. Each of these groups may have a substituent at an arbitrary position, for example, an alkyl group (including a cycloalkyl group and an aralkyl group, preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, Particularly preferred are those having 1 to 8 carbon atoms, for example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, tert-butyl group, n-heptyl group, n-octyl group, n -Decyl group, n-undecyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, benzyl group, phenethyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably). 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 2-butenyl group, and a 3-pentenyl group. Nyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably 2 to 8 carbon atoms, such as propargyl group and 3-pentynyl group), aryl group ( Preferably it has 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenyl group, a p-tolyl group, an O-aminophenyl group, and a naphthyl group. .), An amino group (preferably having a carbon number of 0 to 20, more preferably a carbon number of 0 to 10, particularly preferably a carbon number of 0 to 6, such as an amino group, a methylamino group, an ethylamino group, a dimethylamino group. , Diethylamino group, diphenylamino group, dibenzylamino group, etc.), imino group (preferably having 1 to 20 carbon atoms, more preferably having 1 to 18 carbon atoms, particularly preferably Or an alkoxy group (preferably having a carbon number of 1 to 20, more preferably a carbon number of 1 to 12, particularly preferably a carbon atom), for example, a methylimino group, an ethylimino group, a propylimino group, or a phenylimino group. For example, a methoxy group, an ethoxy group, a butoxy group, etc.), an aryloxy group (preferably having 6-20 carbon atoms, more preferably 6-16 carbon atoms, and particularly preferably 6-12 carbon atoms). Yes, for example, phenyloxy group, 2-naphthyloxy group and the like, acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, Acetyl group, benzoyl group, formyl group, pivaloyl group, etc.), alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, Particularly preferably, it has 2 to 12 carbon atoms, for example, a methoxycarbonyl group, an ethoxycarbonyl group, etc., an aryloxycarbonyl group (preferably 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably carbon numbers). 7-10, for example, phenyloxycarbonyl group, etc., acyloxy group (preferably having 1-20 carbon atoms, more preferably having 1-16 carbon atoms, particularly preferably having 1-10 carbon atoms, such as acetoxy group, benzoyl Oxy group, etc.), acylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 10 carbon atoms such as acetylamino group, benzoylamino group), alkoxycarbonylamino group (Preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 2 carbon atoms. 2 and, for example, methoxycarbonylamino, etc., aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino ), Sulfonylamino groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino group, benzenesulfonylamino group, etc.), sulfamoyl groups (Preferably has 0 to 20 carbon atoms, more preferably has 0 to 16 carbon atoms, and particularly preferably has 0 to 12 carbon atoms. For example, sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl group, etc. ), A carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 carbon atom) 16, particularly preferably 1 to 12 carbon atoms, for example, carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, phenylcarbamoyl group, etc., alkylthio group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms). Particularly preferably, it has 1 to 12 carbon atoms, such as a methylthio group, an ethylthio group, etc., an arylthio group (preferably 6 to 20, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms). , For example, phenylthio group), sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonyl group and tosyl group), sulfinyl group (Preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms. Examples thereof include a methanesulfinyl group and a benzenesulfinyl group. ), Ureido groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as ureido group, methylureido group, phenylureido group), phosphoric acid amide Group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide, phenyl phosphoric acid amide), hydroxyl group, mercapto group, halogen Atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, sulfino group, carboxyl group, phosphono group, phosphino group, nitro group, hydroxamic acid group, hydrazino group, heterocyclic group (for example, , Imidazolyl, benzimidazolyl, thiazolyl, benzothiazolyl, carbazolyl, pyridyl, furyl, pipette Jill, like morpholino, etc.) and the like.

  Among the above groups, a salt-forming group such as a hydroxyl group, a mercapto group, a sulfo group, a sulfino group, a carboxyl group, a phosphono group, or a phosphino group may be a salt. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. The substituent is preferably an alkyl group, aralkyl group, alkoxy group, aryl group, alkylthio group, acyl group, acylamino group, imino group, sulfamoyl group, sulfonyl group, sulfonylamino group, ureido group, amino group, halogen atom, nitro Group, heterocyclic group, alkoxycarbonyl group, hydroxyl group, sulfo group, carbamoyl group, carboxyl group, more preferably alkyl group, alkoxy group, aryl group, alkylthio group, acyl group, acylamino group, imino group, sulfonylamino Group, ureido group, amino group, halogen atom, nitro group, heterocyclic group, alkoxycarbonyl group, hydroxyl group, sulfo group, carbamoyl group, carboxyl group, more preferably alkyl group, alkoxy group, aryl group, alkylthio group , Shiruamino group, an imino group, a ureido group, an amino group, a heterocyclic group, an alkoxycarbonyl group, a hydroxyl group, a sulfo group, a carbamoyl group, a carboxyl group. Examples of the amidino group include those having a substituent, and examples of the substituent include an alkyl group (each group such as methyl, ethyl, pyridylmethyl, benzyl, phenethyl, carboxybenzyl, and aminophenylmethyl), an aryl group (phenyl, each group such as p-tolyl, naphthyl, o-aminophenyl, o-methoxyphenyl), a heterocyclic group (2-thiazolyl, 2-pyridyl, 3-pyridyl, 2-furyl, 3-furyl, 2-thieno, 2 -Each group such as imidazolyl, benzothiazolyl, carbazolyl) and the like.

Examples of the divalent linking group containing at least one oxygen atom, sulfur atom or nitrogen atom represented by J ₃₁ include the following. Moreover, these combinations may be sufficient.

  Here, Re and Rf are respectively synonymous with the contents defined in Ra to Rd described above.

The aromatic hydrocarbon group represented by H ₃₁ Ar is preferably a group having 6 to 30 carbon atoms, more preferably a monocyclic or condensed ring aryl group having 6 to 20 carbon atoms, such as phenyl Group, a naphthyl group, etc. are mentioned, Especially preferably, it is a phenyl group. The aromatic heterocyclic group represented by H ₃₁ Ar is a 5- to 10-membered unsaturated heterocyclic group containing at least one atom of N, O and S, and the heterocyclic ring in these groups is It may be a single ring or may form a condensed ring with another ring. The heterocyclic ring in such a heterocyclic group is preferably a 5- to 6-membered aromatic heterocyclic ring and a benzo-fused ring thereof, more preferably a 5- to 6-membered aromatic heterocyclic ring containing a nitrogen atom, and The benzo-fused ring is more preferably a 5- to 6-membered aromatic heterocycle containing 1 to 2 nitrogen atoms and the benzo-fused ring.

  Specific examples of the heterocyclic group include, for example, thiophene, furan, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, And groups derived from quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, benzothiazoline, benzotriazole, tetrazaindene, carbazole, and the like. The heterocyclic group is preferably imidazole, pyrazole, pyridine, pyrazine, indole, indazole, thiadiazole, oxadiazole, quinoline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, benzothiazoline, benzotriazole, A group consisting of tetrazaindene and carbazole, more preferably a group derived from imidazole, pyridine, pyrazine, quinoline, phenazine, tetrazole, thiazole, benzoxazole, benzimidazole, benzothiazole, benzothiazoline, benzotriazole, carbazole Is mentioned.

The aromatic hydrocarbon group and aromatic heterocyclic group represented by H ₃₁ Ar may have a substituent, and examples of the substituent include the same groups as those exemplified as the substituent for T31. The preferred range is also the same. These substituents may be further substituted, and when there are two or more substituents, each may be the same or different. The group represented by H ₃₁ Ar is preferably an aromatic heterocyclic group.

The aliphatic hydrocarbon group, aryl group and heterocyclic group represented by Ra, Rb, Rc and Rd are the same as the examples of the aliphatic hydrocarbon group, aryl group and heterocyclic group in T _31. The preferable range is also the same. The acyl group represented by Ra, Rb, Rc, and Rd is an aliphatic or aromatic group having 1 to 12 carbon atoms, and specifically includes groups such as acetyl, benzoyl, formyl, and pivaloyl. The nitrogen-containing heterocyclic group formed by bonding between Ra and Rb, Rc and Rd, Ra and Rc, or Rb and Rd is a 3- to 10-membered saturated or unsaturated heterocyclic group (for example, a piperidine ring, piperazine Ring, acridine ring, pyrrolidine ring, pyrrole ring, morpholine ring, etc.).

Specific examples of acid anions as ions necessary for canceling out the charge in the molecule represented by M ₃₁ include, for example, halogen ions (for example, chlorine ions, bromine ions, iodine ions, etc.), p-toluenesulfonic acid ions. Perchlorate ion, boron tetrafluoride ion, sulfate ion, methyl sulfate ion, ethyl sulfate ion, methanesulfonate ion, trifluoromethanesulfonate ion and the like.

  The supersensitizer used in the present invention is preferably used in an amount of 0.001 to 1.0 mol per mol of silver in a photosensitive layer containing an organic silver salt and silver halide grains. Particularly preferred is an amount of 0.01 to 0.5 mole per mole of silver.

  Binders suitable for the photothermographic material of the present invention are transparent or translucent and generally colorless, and are natural polymer synthetic resins, polymers and copolymers, and other media forming films such as gelatin, gum arabic, poly (vinyl) Alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (Styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), Poly (urethane) , Phenoxy resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and polyamides. It may be hydrophilic or non-hydrophilic.

  Preferred binders for the photosensitive layer of the photothermographic material of the invention are polyvinyl acetals, and a particularly preferred binder is polyvinyl butyral. Details will be described later. For non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters that are polymers with higher softening temperatures, especially polymers such as triacetyl cellulose and cellulose acetate butyrate are used. preferable. If necessary, the above binders can be used in combination of two or more.

Such a binder is used in an effective range to function as a binder. The effective range can be easily determined by one skilled in the art. For example, as an index for holding at least an aliphatic carboxylic acid silver salt in the photosensitive layer, the ratio of the binder to the aliphatic carboxylic acid silver salt is 15: 1 to 1: 2, particularly 8: 1 to 1: 1. A range is preferred. That is, it is preferable amount of binder of the photosensitive layer is 1.5~6g / m ^2. More preferably, it is 1.7-5 g / m < ² >. If it is less than 1.5 g / m ² , the density of the unexposed area is significantly increased and may not be used.

  In this invention, it is preferable that the heat transition point temperature after developing at the temperature of 100 degreeC or more is 46-200 degreeC. The heat transition temperature referred to in the present invention is a value indicated by the VICAT softening point or ring-and-ball method, and is a differential scanning calorimeter (DSC), for example, EXSTAR 6000 (manufactured by Seiko Denshi), DSC220C (manufactured by Seiko Denshi Kogyo). , DSC-7 (manufactured by Perkin Elmer) or the like, and refers to an endothermic peak when a thermally developed photosensitive layer is isolated and measured. Generally, a polymer compound has a glass transition point Tg, but in a photothermographic material, a large endothermic peak appears at a position lower than the Tg value of the binder resin used in the photosensitive layer. The glass transition temperature (Tg) was determined by the method described in “Polymer Handbook” III-139-179 (1966, Wiley and Sun, Inc.) by Brand Wrap, and the binder was a copolymer resin. Tg in the case of is obtained by the following equation.

Tg (copolymer) (° C.) = V1Tg1 + v2Tg2 +... + VnTgn
In the formula, v1, v2,... Vn represent mass fractions of monomers in the copolymer, and Tg1, Tg2,... Tgn are single polymers obtained from the respective monomers in the copolymer. Tg (° C.) of The accuracy of Tg calculated according to the above equation is ± 5 ° C.

  In the photothermographic material of the invention, a conventionally known polymer compound may be used as the binder contained in the photosensitive layer containing an aliphatic carboxylic acid silver salt, silver halide grains, a reducing agent, etc. on the support. it can. The Tg is 70 to 105 ° C., the number average molecular weight is 1,000 to 1,000,000, preferably 10,000 to 500,000, and the degree of polymerization is about 50 to 1,000. Examples of such include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic ester, styrene, butadiene, ethylene, vinyl butyral, vinyl acetal, There are compounds made of a polymer or copolymer containing an ethylenically unsaturated monomer such as vinyl ether as a constituent unit, polyurethane resins, and various rubber resins.

  Moreover, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicone resin, epoxy-polyamide resin, polyester resin, and the like can be given. These resins are described in detail in “Plastic Handbook” issued by Asakura Shoten. There is no restriction | limiting in particular in these high molecular compounds, A homopolymer or a copolymer may be sufficient if the glass transition temperature (Tg) of the induced | guided | derived polymer exists in the range of 70-105 degreeC.

  Polymers or copolymers containing such ethylenically unsaturated monomers as structural units include acrylic acid alkyl esters, acrylic acid aryl esters, methacrylic acid alkyl esters, methacrylic acid aryl esters, alkyl cyanoacrylates. Ester, cyanoacrylic acid aryl ester and the like, and the alkyl group and aryl group thereof may or may not be substituted, specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, hexyl, cyclohexyl, benzyl, chlorobenzyl, octyl, stearyl, sulfopropyl, N-ethyl-phenylaminoethyl, 2- (3-phenylpropyloxy) ethyl , Dimethyla Nophenoxyethyl, furfuryl, tetrahydrofurfuryl, phenyl, cresyl, naphthyl, 2-hydroxyethyl, 4-hydroxybutyl, triethylene glycol, dipropylene glycol, 2-methoxyethyl, 3-methoxybutyl, 2-acetoxyethyl, 2 -Acetoacetoxyethyl, 2-ethoxyethyl, 2-iso-propoxyethyl, 2-butoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- (2-ethoxyethoxy) ethyl, 2- (2-butoxyethoxy) Examples thereof include ethyl, 2-diphenylphosphorylethyl, ω-methoxypolyethylene glycol (added mole number n = 6), allyl, dimethylaminoethylmethyl chloride salt and the like.

  In addition, the following monomers can be used. Specific examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxyacetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate. N-substituted acrylamides, N-substituted methacrylamides and acrylamides, methacrylamide: N-substituents include methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl, benzyl, hydroxymethyl, methoxyethyl, dimethyl Aminoethyl, phenyl, dimethyl, diethyl, β-cyanoethyl, N- (2-acetoacetoxyethyl), diacetone and the like; olefins: for example, dicyclopentadiene, ethylene, propylene, 1-butene 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene, etc .; styrenes: for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, tert-butylstyrene, Chlormethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, vinyl benzoic acid methyl ester, etc .; Vinyl ethers: for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethyl vinyl ether, etc. N-substituted maleimides: As N-substituents, methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl, benzene Those having zyl, n-dodecyl, phenyl, 2-methylphenyl, 2,6-diethylphenyl, 2-chlorophenyl, etc .; others include butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate, malein Diethyl acid, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, glycidyl acrylate, glycidyl methacrylate, N-vinyloxazolidone, N-vinyl Examples include pyrrolidone, acrylonitrile, methacrylonitrile, methylenemalonnitrile, vinylidene chloride and the like.

  Among these, particularly preferred examples include methacrylic acid alkyl esters, methacrylic acid aryl esters, styrenes, and the like. Among such polymer compounds, it is preferable to use a polymer compound having an acetal group. The polymer compound having an acetal group is preferable because it is excellent in compatibility with the aliphatic carboxylic acid to be produced and has a great effect of preventing the film from being softened.

  As the polymer compound having an acetal group, a compound represented by the following general formula [6] is particularly preferable.

In the formula, R ₅₁ represents an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, but is preferably a group other than an aryl group. R ₅₂ represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group, —COR ₅₃ or —CONHR ₅₃ . R ₅₃ has the same meaning as R ₅₁ .

The unsubstituted alkyl group represented by R ₅₁ , R ₅₂ , and R ₅₃ is preferably an alkyl group having 1 to 20 carbon atoms, particularly preferably 1 to 6 carbon atoms. These may be linear or branched, and preferably a linear alkyl group. Examples of such unsubstituted alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-amyl, tert-amyl, n -Hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, tert-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-octadecyl group, etc. Is particularly preferably a methyl group or a propyl group.

  As an unsubstituted aryl group, a C6-C20 thing is preferable, for example, a phenyl group, a naphthyl group, etc. are mentioned. Examples of the group that can be substituted with the above alkyl group and aryl group include an alkyl group (for example, methyl group, n-propyl group, tert-amyl group, tert-octyl group, n-nonyl group, dodecyl group, etc.), aryl group (For example, phenyl group), nitro group, hydroxyl group, cyano group, sulfo group, alkoxy group (for example, methoxy group), aryloxy group (for example, phenoxy group), acyloxy group (for example, acetoxy group), Acylamino group (for example, acetylamino group), sulfonamide group (for example, methanesulfonamide group), sulfamoyl group (for example, methylsulfamoyl group), halogen atom (for example, fluorine atom, chlorine atom, bromine atom) ), Carboxy group, carbamoyl group (for example, methylcarbamoyl group), alkoxycarbonyl group ( Eg to Metokishiruboniru group), a sulfonyl group (for example, methylsulfonyl group, etc.) and the like. When there are two or more substituents, they may be the same or different. The total carbon number of the substituted alkyl group is preferably 1-20, and the total carbon number of the substituted aryl group is preferably 6-20.

As R ₅₂ , —COR ₅₃ (R ₅₃ is an alkyl group or aryl group) and —CONHR ₅₃ (R ₅₃ is an aryl group) are preferable. a, b, and c are values representing the mass of each repeating unit in mol (mol)%, a is 40 to 86 mol%, b is 0 to 30 mol%, and c is in the range of 0 to 60 mol%. A + b + c = 100 mol%, particularly preferably a is in the range of 50 to 86 mol%, b is 5 to 25 mol%, and c is 0 to 40 mol%. Each repeating unit having a composition ratio of a, b, and c may be composed of only the same one or different ones.

As the polyurethane resin that can be used in the present invention, known resins such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane, and polycaprolactone polyurethane can be used. For all polyurethane shown here, if _{necessary, -COOM, -SO 3 M, -OSO} 3 M, -P = O (OM) 2, -O-P = O (OM) 2, (M is hydrogen An atom or an alkali metal base), —N (R ₅₄ ) ₂ , —N ⁺ (R ₅₄ ) ₃ (R ₅₄ represents a hydrocarbon group, and a plurality of R54s may be the same or different), epoxy It is preferable to use one in which at least one polar group selected from a group, —SH, —CN and the like is introduced by copolymerization or addition reaction. The amount of such a polar group is 10 ⁻¹ to 10 ⁻⁸ mol / g, preferably 10 ⁻² to 10 ⁻⁶ mol / g. In addition to these polar groups, it is preferable to have at least one OH group in total at least one at the polyurethane molecule end. Since OH groups are cross-linked with polyisocyanate which is a curing agent to form a three-dimensional network structure, it is more preferable that the OH groups are contained in the molecule. In particular, it is preferable that the OH group is at the molecular end because the reactivity with the curing agent is high. The polyurethane preferably has 3 or more OH groups at the molecular terminals, and particularly preferably 4 or more. When polyurethane is used, the glass transition temperature is preferably 70 to 105 ° C., the elongation at break is 100 to 2000%, and the stress at break is preferably 0.5 to 100 N / mm ² .

  The polymer compound according to the present invention can be synthesized by a general synthesis method described in “Vinyl acetate resin” edited by Ichiro Sakurada (Polymer Chemistry Press, 1962) and the like.

  These polymer compounds may be used alone as a binder, or two or more kinds may be blended and used. In the photosensitive silver salt-containing layer (preferably photosensitive layer) according to the present invention, the above polymer is used as a main binder. The main binder as used herein refers to “a state in which the polymer occupies 50% by mass or more of the total binder of the photosensitive silver salt-containing layer”. Therefore, other polymers may be blended and used within a range of less than 50% by mass of the total binder. These polymers are not particularly limited as long as the polymers according to the present invention are soluble. More preferred are polyvinyl acetate, polyacrylic resin, urethane resin and the like.

  In the present invention, it is known that the use of a crosslinking agent for the binder improves the film formation and reduces development unevenness. However, it prevents fogging during storage and produces printed silver after development. There is also an inhibitory effect.

  Examples of the crosslinking agent used in the present invention include various crosslinking agents conventionally used for silver halide photographic light-sensitive materials, such as aldehyde-based, epoxy-based, and ethyleneimine-based compounds described in JP-A-50-96216. , Vinylsulfone-based, sulfonic acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents can be used, but the following isocyanate-based compounds, silane compounds, epoxy compounds, or acid anhydrides are preferable.

  An isocyanate-based and thioisocyanate-based crosslinking agent represented by the following general formula [7], which is one of the preferred ones, will be described.

General formula [7] _{X 2 = C = N-L-} (N = C = X 2) v
In the formula, v is 1 or 2, L is an alkyl group, an alkenyl group, an aryl group or an alkylaryl group, a v + 1 valent linking group, and X is an oxygen or sulfur atom.

  In the compound represented by the general formula [7], the aryl ring of the aryl group may have a substituent. Examples of preferred substituents are selected from halogen atoms (for example, bromine atoms or chlorine atoms), hydroxyl groups, amino groups, carboxyl groups, alkyl groups and alkoxy groups.

  The isocyanate-based crosslinking agent includes isocyanates having at least two isocyanate groups and adducts thereof (adducts), and more specifically, aliphatic diisocyanates and aliphatic diisocyanates having a cyclic group. Benzene diisocyanates, naphthalene diisocyanates, biphenyl isocyanates, diphenylmethane diisocyanates, triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates and divalent or trivalent with these isocyanates Examples include adducts with polyalcohols.

  As a specific example, isocyanate compounds described on pages 10 to 12 of JP-A-56-5535 can be used.

  Note that the adduct body of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion, and prevent layer peeling, image shift, and bubble generation. Such isocyanate may be placed in any part of the photothermographic material. For example, in the support (especially when the support is paper, it can be included in the size composition), photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any one of these layers, and can be added to one or more of these layers.

  In addition, as the thioisocyanate-based crosslinking agent that can be used in the present invention, compounds having a thioisocyanate structure corresponding to the above isocyanates are also useful.

  The amount of the crosslinking agent used in the present invention is in the range of 0.001 to 2 mol, preferably 0.005 to 0.5 mol, with respect to 1 mol of silver.

  The isocyanate compound and thioisocyanate compound that can be contained in the present invention are preferably compounds that function as the above-mentioned crosslinking agent, but in the above general formula, v is zero (0), that is, the functional group is one. Even if it is a compound which has only, the result which is good is obtained.

  Examples of the silane compound that can be used as a crosslinking agent in the present invention include compounds represented by general formula (1) or general formula (2) described in JP-A No. 2001-264930.

In these general formulas, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each an optionally substituted linear, branched or cyclic C 1-30 carbon atom. Alkyl group (methyl group, ethyl group, butyl group, octyl group, dodecyl group, cycloalkyl group, etc.), alkenyl group (propenyl group, butenyl group, nonenyl group, etc.), alkynyl group (acetylene group, bisacetylene group, phenylacetylene) Group), aryl group or heterocyclic group (phenyl group, naphthyl group, tetrahydropyran group, pyridyl group, furyl group, thiophenyl group, imidazole group, thiazole group, thiadiazole group, oxadiazole group, etc.), substituent As an electron-withdrawing substituent or an electron-donating substituent.

^{R 1, R 2, R 3} , R 4, preferably R ^5, R ^6, at least 1 Tsuga耐diffusible group or adsorptive group substituents selected from R ⁷ and R ^8, especially R ² A diffusion-resistant group or an adsorptive group is preferable.

  The non-diffusible group is also called a ballast group, and is preferably an aliphatic group having 6 or more carbon atoms or an aryl group into which an alkyl group having 3 or more carbon atoms is introduced. Diffusion resistance varies depending on the amount of binder and cross-linking agent used. By introducing a diffusion-resistant group, the intramolecular movement distance at room temperature is suppressed, and the reaction over time can be suppressed.

  The epoxy compound that can be used as the crosslinking agent is not particularly limited as long as it has one or more epoxy groups and the number of epoxy groups, molecular weight, and the like. The epoxy group is preferably contained in the molecule as a glycidyl group via an ether bond or an imino bond. Moreover, any of a monomer, an oligomer, a polymer, etc. may be sufficient as an epoxy compound, and the number of the epoxy groups which exist in a molecule | numerator is about 1-10 normally, Preferably it is 2-4. When the epoxy compound is a polymer, it may be a homopolymer or a copolymer, and the particularly preferred range of the number average molecular weight Mn is about 2000 to 20000.

  As the epoxy compound, a compound represented by the following general formula [8] is preferable.

In the general formula [8], the substituent of the alkylene group represented by R ₉₀ is preferably a group selected from a halogen atom, a hydroxyl group, a hydroxyalkyl group, or an amino group. The linking group represented by R ₉₀ preferably has an amide linking moiety, an ether linking moiety, or a thioether linking moiety. -SO ₂ As the divalent linking group represented by _{X 9 -, - SO 2 NH} -, - S -, - O-, or -NR ₉₁ - are preferred. Here, R ₉₁ is a monovalent group and is preferably an electron withdrawing group.

These epoxy compounds may be used alone or in combination of two or more. The addition amount is not particularly limited, but is preferably in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol / m ² , more preferably in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol / m ² . It is.

  The epoxy compound can be added to any layer on the photosensitive layer side of the support, such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. Can be added. Moreover, it can add to the arbitrary layer on the opposite side to the photosensitive layer of a support body collectively. In addition, any layer may be sufficient in the type of photosensitive material in which a photosensitive layer exists on both surfaces.

  An acid anhydride is a compound having at least one acid anhydride group represented by the following structural formula.

-CO-O-CO-
The acid anhydride is not particularly limited as long as it has at least one such acid anhydride group, and the number, molecular weight, and the like of the acid anhydride group are not limited, but a compound represented by the following general formula [9] is preferable.

  In the general formula [9], Z represents an atomic group necessary for forming a monocyclic or polycyclic system. These ring systems may be unsubstituted or substituted. Examples of substituents include alkyl groups (eg, methyl, ethyl, hexyl), alkoxy groups (eg, methoxy, ethoxy, octyloxy), aryl groups (eg, phenyl, naphthyl, tolyl), hydroxyl groups, aryloxy groups (Eg, phenoxy), alkylthio group (eg, methylthio, butylthio), arylthio group (eg, phenylthio), acyl group (eg, acetyl, propionyl, butyryl), sulfonyl group (eg, methylsulfonyl, phenylsulfonyl), acylamino group Sulfonylamino group, acyloxy group (for example, acetoxy, benzoxy), carboxyl group, cyano group, sulfo group, and amino group. As the substituent, those not containing a halogen atom are preferable.

These acid anhydrides may be used alone or in combination of two or more. The addition amount is not particularly limited, but is preferably in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol / m ² , more preferably in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol / m ² . It is.

  In the present invention, the acid anhydride can be added to any layer on the photosensitive layer side of the support, such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. It can be added to two or more layers. Moreover, you may add to the same layer as the said epoxy compound.

  The photothermographic material of the present invention forms a photographic image by heat development processing, and includes a reducible silver source (aliphatic carboxylic acid silver salt), silver halide grains, a reducing agent and, if necessary, silver. It is preferable to contain a color toning agent that adjusts the color tone in a dispersed state in a normal (organic) binder matrix.

  Examples of suitable toning agents are disclosed in RD 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136 and 4,021,249. ing. A particularly preferred colorant is a combination of phthalazinone or phthalazine with phthalic acids and phthalic anhydrides.

  Note that, regarding the color tone of an output image for medical diagnosis in the past, it is said that a cold tone image tone makes it easier for an X-ray photograph reader to obtain a more accurate diagnostic observation result of a recorded image. Here, the cool image tone is a pure black tone or a bluish black tone of a black image, and the warm image tone is a black tone of a black image having a brownish tone. To tell.

The terms “more cold” and “more warm” regarding the color tone are determined by the hue angle hab at the minimum density Dmin and the optical density D = 1.0. The hue angle hab is calculated using the color coordinates a ^* and b ^* of the color space L ^* a ^* b ^* color space, which is a color space having a perceptually uniform rate recommended in 1976 by the International Commission on Illumination (CIE). It is calculated by the following formula.

hab = tan ⁻¹ (b ^* / a ^* )
In the present invention, the preferred hab range is 180 ° <hab <270 °, more preferably 200 ° <hab <270 °, and most preferably 220 ° <hab <260 °.

  In the present invention, the surface layer of the photothermographic material (even when a non-photosensitive layer is provided on the opposite side of the photosensitive layer side with the support sandwiched) is handled before development or image after thermal development. It is preferable to contain a matting agent for preventing damage, and it is preferable to contain 0.1 to 30% by mass with respect to the binder.

  The material of the matting agent may be either organic or inorganic. Examples of inorganic substances include silica described in Swiss Patent No. 330,158 and the like, glass powder described in French Patent No. 1,296,995 and the like, and alkali described in British Patent No. 1,173,181 and the like. Earth metals or carbonates such as cadmium and zinc can be used as the matting agent. Examples of organic substances include starch described in U.S. Pat. No. 2,322,037 and the like, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and Japanese Patent Publication No. 44-3643. Polyvinyl alcohol described, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, polyacrylonitrile described in US Pat. No. 3,079,257, US Pat. No. 3,022,169 etc. An organic matting agent such as prepared polycarbonate can be used.

  The matting agent preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. The coefficient of variation of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less.

  Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

(Standard deviation of particle size) / (Average value of particle size) × 100
The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed and applied in advance in the coating solution, or a method in which the matting agent is sprayed after the coating solution is applied and before drying is completed. May be. When a plurality of types of matting agents are added, both methods may be used in combination.

  Examples of the support material used in the photothermographic material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (for example, aluminum), etc. Is preferably one that can be processed into a flexible sheet or roll. Accordingly, the support in the photothermographic material of the present invention is preferably a plastic film (for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, cellulose triacetate film or polycarbonate film). In the present invention, a biaxially stretched polyethylene terephthalate film is particularly preferred. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

  In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layers in order to improve the chargeability. These may be contained in any layer, but are preferably contained in an undercoat layer, a backing layer, a layer between the photosensitive layer and the undercoat, and the like. In the present invention, the conductive compounds described in US Pat. No. 5,244,773, columns 14 to 20 are preferably used.

  The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. For example, a protective layer is provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and in order to prevent sticking between the photothermographic materials on the opposite side of the support or in the photothermographic material roll. A backcoat layer is preferably provided. Binders used in these protective layers and backcoat layers have a glass transition point higher than that of the heat-developable layer, and polymers such as scratches and deformations, such as cellulose acetate and cellulose acetate butyrate, It is chosen from among them. In order to widen the latitude, it is one of preferred embodiments of the present invention to provide two or more photosensitive layers on one side of the support or one or more layers on both sides of the support.

  In the photothermographic material of the present invention, a filter layer is formed on the same side as or opposite to the photosensitive layer in order to control the amount of light transmitted through the photosensitive layer or the wavelength distribution, or a dye or pigment is added to the photosensitive layer. It is preferable to contain.

  As the dye used, known compounds that absorb light in various wavelength regions can be used depending on the color sensitivity of the photothermographic material.

  For example, when the photothermographic material of the present invention is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (in this specification, thiopyrylium). It is preferred to use a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), and a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. .

  The compound having a squarylium nucleus is a compound having 1-cyclobuten-2-hydroxy-4-one in the molecular structure, and the compound having a croconium nucleus is 1-cyclopentene-2-hydroxy- in the molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Hereinafter, in the present specification, these pigments are collectively referred to as squarylium dyes for convenience.

  As the dye, a compound described in JP-A-8-201959 is also preferable.

  The photothermographic material of the present invention may be formed by preparing a coating solution obtained by dissolving or dispersing the above-described constituent layers in a solvent, applying a plurality of coating solutions simultaneously, and then performing a heat treatment. preferable. Here, "multiple simultaneous multi-layer coating" means that a coating solution for each constituent layer (for example, a photosensitive layer and a protective layer) is prepared, and when coating this onto a support, each layer is individually coated and dried repeatedly. In other words, it means that each constituent layer can be formed in such a state that the multilayer coating and drying can be performed simultaneously. That is, the upper layer is provided before the remaining amount of the total solvent in the lower layer reaches 70% by mass or less.

  There are no particular restrictions on the method of applying multiple layers of each constituent layer simultaneously, and for example, a known method such as a bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, or extrusion coating method may be used. Can do. Of these, a pre-weighing type coating method called an extrusion coating method is more preferable. Since the extrusion coating method does not volatilize on the slide surface unlike the slide coating method, it is suitable for precision coating and organic solvent coating. Although this coating method has been described on the side having the photosensitive layer, the same applies to the case of coating with undercoating when providing the backcoat layer.

In the present invention, the coated silver amount is preferably selected in accordance with the purpose of the photothermographic material, but is preferably 0.1 to 2.5 g / m ² for the purpose of medical images. . Furthermore, 0.5 to 1.5 g / m ² is preferable. Among the silver coating amounts, those derived from silver halide preferably occupy 2 to 18% by mass, more preferably 3 to 15% by mass, based on the total silver amount.

In the present invention, the coating density of silver halide grains having a particle diameter of 0.01 μm or more (equivalent particle diameter equivalent to a sphere) is preferably 1 × 10 ¹⁴ to 1 × 10 ¹⁸ particles / m ² . Furthermore, 1 * 10 < ¹⁵ > -1 * 10 < ¹⁷ > piece / m < ² > is preferable.

Furthermore, the coating density of the aliphatic carboxylic acid silver salt according to the present invention is 10 ⁻¹⁷ to 10 ⁻¹⁵ g, more preferably 10 ⁻¹⁶ per silver halide grain having a particle diameter of 0.01 μm or more (equivalent particle diameter equivalent to sphere). ~10 ^-14 g is preferable.

  When coated under the conditions within the above range, it is preferable from the viewpoint of the optical maximum density of the silver image per fixed coated silver amount, that is, the silver coating amount (covering power) and the color tone of the silver image. Results are obtained.

  In the present invention, the development conditions vary depending on the equipment, apparatus or means used, but typically involve heating the photothermographic material exposed imagewise at a suitable high temperature. The latent image obtained after exposure is developed by heating the photothermographic material at a moderately high temperature (for example, about 100 to 200 ° C.) for a sufficient time (generally about 1 second to about 2 minutes). Can do. When the heating temperature is 100 ° C. or lower, sufficient image density cannot be obtained in a short time. When the heating temperature is 200 ° C. or higher, the binder melts, and not only the image itself, such as transfer to a roller, but also the transportability and the developing machine are adversely affected. Effect. By heating, a silver image is generated by a redox reaction between the aliphatic carboxylic acid silver salt (which functions as an oxidizing agent) and the reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside.

  The heating device, apparatus, and means may be a heating means typical as a heat generator using a hot plate, iron, hot roller, carbon, white titanium, or the like. More preferably, the photothermographic material provided with the protective layer is subjected to heat treatment by bringing the surface having the protective layer into contact with the heating means, in terms of uniform heating, thermal efficiency, workability, etc. Preferably, the surface is conveyed while being brought into contact with a heat roller, and heat-treated for development.

  In the exposure of the photothermographic material of the present invention, it is desirable to use an appropriate light source for the color sensitivity imparted to the photothermographic material. For example, if the photothermographic material is sensitive to infrared light, it can be applied to any light source as long as it is in the infrared light range. An infrared semiconductor laser (780 nm, 820 nm) is more preferably used because it can be made transparent.

  In the present invention, the exposure is preferably performed by laser scanning exposure, but various methods can be adopted as the exposure method. For example, as a first preferred method, there is a method using a laser scanning exposure machine in which the angle formed by the exposure surface of the photothermographic material and the scanning laser beam is not substantially perpendicular.

  Here, “substantially not perpendicular” means that the angle closest to the vertical during laser scanning is preferably 55 to 88 degrees, more preferably 60 to 86 degrees, and even more preferably 65 to 84 degrees. , And most preferably 70 to 82 degrees.

  The beam spot diameter on the photosensitive material exposure surface when the laser beam is scanned onto the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable in that the smaller the spot diameter, the smaller the angle of deviation of the laser incident angle from the vertical. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as generation of interference fringe-like unevenness.

  As a second method, it is also preferable to perform exposure using a laser scanning exposure machine that emits scanning laser light that is a vertical multi. Compared with a longitudinal single mode scanning laser beam, image quality degradation such as occurrence of interference fringe-like unevenness is reduced.

  In order to make it vertically multi-ply, methods such as using return light by multiplexing and applying high-frequency superposition are preferable. The vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

In the image recording methods of the first and second aspects described above, the laser used for the scanning exposure is generally well-known solid laser such as ruby laser, YAG laser, glass laser; HeNe laser, Ar ion. Gas laser such as laser, Kr ion laser, CO ₂ laser, CO laser, HeCd laser, N ₂ laser, excimer laser; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb laser, etc. Semiconductor lasers; chemical lasers, dye lasers, and the like can be selected and used in a timely manner, but among these, it is preferable to use a semiconductor laser having a wavelength of 600 to 1200 nm from the viewpoint of maintenance and the size of the light source. In a laser used in a laser imager or a laser image setter, the beam spot diameter on the exposed surface of the material when scanned by a photothermographic material is generally 5 to 75 μm as the minor axis diameter, and the major axis diameter. The laser beam scanning speed can be set to an optimum value for each photosensitive material depending on the sensitivity and laser power at the laser oscillation wavelength unique to the photothermographic material.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “mass%”.

Example 1
<Production of support>
One side of a polyethylene terephthalate film base (thickness: 175 μm) colored blue with a concentration of 0.170 was subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , and then the following undercoat coating solution was applied thereon. Using A, the undercoat layer a was applied so that the dry film thickness was 0.2 μm. Further, after the other surface was similarly subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , the following undercoat coating solution B was used thereon to form the undercoat layer b with a dry film thickness. It coated so that it might be set to 0.1 micrometer.

  Thereafter, heat treatment was performed at 130 ° C. for 15 minutes in a heat treatment type oven having a film transport device composed of a plurality of roll groups.

(Undercoating liquid A)
Copolymer latex liquid (solid content 30%) 270 g of n-butyl acrylate 30%, tert-butyl acrylate 20%, styrene 25% and 2-hydroxyethyl acrylate 25%, surfactant UL-1 0.6 g and methylcellulose 0.5 g was mixed. Furthermore, 1.3 g of silica particles (Syloid 350, manufactured by Fuji Silysia) was added to 100 g of water, and dispersed for 30 minutes with an ultrasonic disperser (manufactured by ALEX Corporation, Ultrasonic Generator, frequency 25 kHz, 600 W). The dispersion liquid was added, and finally it was made up to 1000 ml with water to obtain an undercoat coating liquid A.

(Preparation of colloidal tin oxide dispersion)
A homogeneous solution was prepared by dissolving 65 g of stannic chloride hydrate in 2000 ml of a water / ethanol mixed solution. Subsequently, this was boiled and the coprecipitate was obtained. The generated precipitate was taken out by decantation and washed several times with distilled water. Silver nitrate is dropped into distilled water from which the precipitate has been washed, and after confirming that there is no reaction of chlorine ions, distilled water is added to the washed precipitate to make a total volume of 2000 ml. Further, 40 ml of 30% aqueous ammonia was added, the aqueous solution was heated, and concentrated to a volume of 470 ml to prepare a colloidal tin oxide dispersion.

(Undercoating liquid B)
2. 37.5 g of the colloidal tin oxide dispersion, copolymer latex liquid (solid content 30%) of n-butyl acrylate 20%, tert-butyl acrylate 30%, styrene 27% and 2-hydroxyethyl acrylate 28%. 14.8 g of copolymer latex liquid (solid content 30%) of 7 g, n-butyl acrylate 40%, styrene 20%, glycidyl methacrylate 40% and 0.1 g of surfactant UL-1 are mixed, and 1000 ml with water The undercoat coating solution B was finished.

<Back side application>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (Eastman Chemical, CAB381-20) and 4.5 g of a polyester resin (Bostic, VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved solution, and 4.5 g of F-type activator (Asahi Glass Co., Surflon KH40) and F-type activator (Dainippon Ink, Inc.) dissolved in 43.2 g of methanol. Co., MegaFag F120K) 2.3 g was added and stirred well until dissolved. Finally, 75 g of silica (WR Grace, Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% with a dissolver type homogenizer was added and stirred to prepare a coating solution for the back surface side.

  The back surface coating solution thus prepared was applied and dried by an extrusion coater on the undercoat layer b described above so that the dry film thickness was 3.5 μm. It dried for 5 minutes using the drying air with a drying temperature of 100 degreeC, and dew point temperature of 10 degreeC.

<< Preparation of silver halide emulsion A >>
Solution (A1)
Phenylcarbamoylated gelatin 88.3g
Compound (A) (10% methanol aqueous solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water Solution (B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
Solution (C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finish to 660 ml with water Solution (D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
Iridium chloride (1% solution) 0.93ml
Finish to 1982ml with water Solution (E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount solution (F1)
Potassium hydroxide 0.71g
Finish to 20 ml with water Solution (G1)
56% acetic acid aqueous solution 18.0 ml
Solution (H1)
Anhydrous sodium carbonate 1.72 g
Finish to 151 ml with water Compound (A):
_{HO (CH 2 CH 2 O)} n (CH (CH 3) CH 2 O) 17 (CH 2 CH 2 O) m H
(M + n = 5-7)
Using the mixing stirrer shown in Japanese Patent Publication Nos. 58-58288 and 58-58289, ¼ amount of the solution (B1) and the whole amount of the solution (C1) were adjusted to a temperature of 30 ° C. and a pAg of 8.09. While being controlled, the nucleation was performed by adding 4 minutes 45 seconds by the simultaneous mixing method. After 1 minute, the entire amount of solution (F1) was added. During this time, the pAg was adjusted as appropriate using the aqueous solution (E1). After 6 minutes, 3/4 amount of the solution (B1) and the whole amount of the solution (D1) were added over 14 minutes and 15 seconds by a simultaneous mixing method while controlling the temperature at 30 ° C. and pAg 8.09. After stirring for 5 minutes, the temperature was lowered to 40 ° C., the whole amount of the solution (G1) was added, and the silver halide emulsion was allowed to settle. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, the silver halide emulsion was precipitated. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution (H1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount was 1161 g per mol of silver to obtain an emulsion.

  This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 0.040 μm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

  Next, 240 ml of sulfur sensitizer S-5 (0.5% methanol solution) was added to the above emulsion, and gold sensitizer Au-5 corresponding to 1/20 mol of this sensitizer was added, and the mixture was heated to 55 ° C. The mixture was stirred for 120 minutes for chemical sensitization. This is designated as silver halide emulsion A.

<< Preparation of powdered aliphatic carboxylic acid silver salt A >>
130.8 g of behenic acid, 67.7 g of arachidic acid, 43.6 g of stearic acid, and 2.3 g of palmitic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 mol / L sodium hydroxide aqueous solution was added, and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the sodium fatty acid solution at 55 ° C., 45.3 g of the above silver halide emulsion A and 450 ml of pure water were added and stirred for 5 minutes.

  Next, 702.6 ml of a 1 mol / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an aliphatic carboxylic acid silver salt dispersion. Thereafter, the obtained aliphatic carboxylic acid silver salt dispersion was transferred to a water-washing vessel, deionized water was added and stirred, and then allowed to stand to float and separate the aliphatic carboxylic acid silver salt dispersion. Was removed. Thereafter, washing with deionized water and drainage were repeated until the electrical conductivity of the drainage reached 50 μS / cm, and centrifugal dehydration was carried out. Then, the cake-like aliphatic carboxylic acid silver salt thus obtained was added to the airflow dryer flash jet. Using a drier (manufactured by Seishin Enterprise Co., Ltd.), a powdered aliphatic carboxylic acid silver salt A was obtained by drying until the water content became 0.1% under the operating conditions of nitrogen gas atmosphere and dryer inlet hot air temperature. . An infrared moisture meter was used to measure the water content of the aliphatic carboxylic acid silver salt composition.

<< Preparation of Preliminary Dispersion A >>
While dissolving 1.57 g of polyvinyl butyral resin B-79 manufactured by Solusia in 1457 g of methyl ethyl ketone and stirring with dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN, 500 g of powdered aliphatic carboxylic acid silver salt A was gradually added. Preliminary dispersion A was prepared by adding and mixing well.

<< Preparation of photosensitive emulsion dispersion A >>
Media type disperser DISPERMAT SL filled with 80% by volume of zirconia beads (Toray manufactured by Toray Industries Inc.) with a diameter of 0.5 mm so that the residence time in the mill is 1.5 minutes using a pump. A photosensitive emulsion dispersion A was prepared by supplying to C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<< Preparation of stabilizer liquid >>
A stabilizer solution was prepared by dissolving 1.0 g of Stabilizer 1 and 0.31 g of potassium acetate in 4.97 g of methanol.

<< Preparation of infrared sensitizing dye liquid A >>
19.2 mg of infrared sensitizing dye 1, 1.488 g of 2-chloro-benzoic acid, 2.7779 g of stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenzimidazole are darkened in 31.3 ml of MEK. The solution was dissolved at a place to prepare an infrared sensitizing dye liquid A.

<< Preparation of Additive Liquid a >>
Silver ion reducing agent (compound described in Table 1) 6.0 g × 10 ⁻³ / m ² , compound represented by general formula (1) (compound and amount described in Table 1), 1.54 g of 4- Methylphthalic acid, 0.48 g of infrared dye 1 was dissolved in 110 g of MEK to obtain an additive solution a.

<< Preparation of additive liquid b >>
3.56 g of antifoggant 2 and 3.43 g of phthalazine were dissolved in 40.9 g of MEK to obtain additive solution b.

<< Preparation of photosensitive layer coating solution A >>
In an inert gas atmosphere (97% nitrogen), the photosensitive emulsion dispersion A (50 g) and 15.11 g of MEK were kept at 21 ° C. with stirring, 390 μl of antifoggant 1 (10% methanol solution) was added, Stir for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 20 minutes. Subsequently, 167 ml of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ° C., 13.31 g of polyvinyl butyral resin B-79 manufactured by Solusia Co. was added as a binder resin and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4% MEK solution) was added. And stirred for 15 minutes. While continuing to stir, the additive solution a (silver ion reducing agent, weighed so that the compound represented by the general formula (1) becomes the addition amount shown in Table 1), 1.6 ml of Desmodur N3300 (manufactured by Mobay) Of aliphatic isocyanate, 10% MEK solution) and 4.27 g of additive liquid b were sequentially added and stirred to obtain photosensitive layer coating liquid A.

<Preparation of matting agent dispersion>
Cellulose acetate butyrate (Eastman Chemical Co., 7.5 g CAB171-15) was dissolved in 42.5 g of MEK, and 5 g of calcium carbonate (Speciality Minerals, Super-Pflex 200) was added thereto, and a dissolver type homogenizer was used. The matting agent dispersion was prepared by dispersing at 8000 rpm for 30 minutes.

<< Preparation of surface protective layer coating liquid >>
While stirring 865 g of MEK (methyl ethyl ketone), 96 g of cellulose acetate butyrate (Eastman Chemical Co., CAB171-15), 4.5 g of polymethylmethacrylic acid (Rohm & Haas Co., Paraloid A-21), vinyl sulfone compound ( 1.5 g of VSC), 1.0 g of benzotriazole, and 1.0 g of F-based activator (Asahi Glass Co., Surflon KH40) were added and dissolved. Next, 30 g of the above matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

<Preparation of photothermographic material sample>
Each sample was produced by simultaneously applying the photosensitive layer coating solution A and the surface protective layer coating solution on the undercoat layer a using a known extrusion coater. The coating was carried out so that the photosensitive layer had an applied silver amount of 1.5 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm. Then, each sample was produced by drying for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

<< Exposure and development process >>
From the emulsion surface side of the sample produced as described above, exposure by laser scanning was given by an exposure machine using an exposure source of a longitudinally multimode semiconductor laser having wavelengths of 810 nm and 814 nm by high frequency superposition. At this time, an image was formed by setting the angle of the exposure surface of the sample and the exposure laser beam to 75 degrees. Note that an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 degrees.

  Thereafter, using an automatic developing machine having a heat drum, the sample was thermally developed at 123 ° C. for 13.5 seconds so that the protective layer of the sample was in contact with the drum surface. At that time, exposure and development were performed in a room adjusted to 23 ° C. and 50% RH. The following measurements and evaluations were performed on the images obtained as described above.

<Measurement of sensitivity, fog, and maximum concentration>
The image obtained by exposure at each wavelength is subjected to density measurement with a Macbeth densitometer (TD-904), and a characteristic curve consisting of a horizontal axis (exposure amount) and a vertical axis (image density) is created. Also, the reciprocal of the ratio of the exposure amount required to give a high density of 1.0 is defined as sensitivity, and expressed as a relative value where the sensitivity of the sample 101 exposed with the semiconductor laser of 810 nm is 100. Further, the minimum density (fogging) and the maximum density were measured.

<Evaluation of color tone>
The color tone of the obtained image was visually observed and evaluated based on the following criteria. Practically, it is preferably rank 4 or higher.

5: Cold black tone does not feel red at all. 4: Cold black tone does not feel red at all. 3: Partially slightly reddish. 2: Partially slightly reddish. 1: At first glance reddish. <Evaluation of image preservation>
For the image obtained by exposure with a 810 nm semiconductor laser, the image density change rate of the minimum density portion and the maximum density portion was measured according to the following method, the color tone change was further evaluated, and the image storage stability was evaluated.

(Minimum density area image storage)
Each of the heat-developed samples prepared in the same manner as the above-described sensitivity, fog, and maximum density measurement methods was subjected to a commercially available white fluorescent lamp with an illuminance of 500 lux on the sample surface in an environment of 45 ° C. and 55% RH. And then irradiated continuously for 3 days. Measure the minimum density (D2) of the sample irradiated with the fluorescent lamp and the minimum density (D1) of the sample not irradiated with the fluorescent lamp, calculate the minimum density change rate (%) from the following formula, and measure the image storage stability of the minimum density part It was. The closer the value is to 100, the better.

Minimum density change rate = D2 / D1 x 100 (%)
(Image storability of the highest density part)
Each of the heat-developed samples prepared in the same manner as the above sensitivity, fog, and maximum density measurement methods was left in an environment of 25 ° C. and 45 ° C. for 3 days, and then the change in the maximum density was measured. The rate of change in image density was measured by the equation, and this was used as a measure of image preservation at the highest density part. The closer the value is to 100, the better.

Image density change rate = maximum density of sample stored at 45 ° C./maximum density of sample stored at 25 ° C. × 100 (%)
(Color change)
For samples prepared by evaluation of image storability at the minimum density area, the change in color tone by fluorescent lamp irradiation, and for samples prepared by evaluation of image storability at the maximum density area, the color tone change by high-temperature (45 ° C) treatment is as follows: It was obtained in five stages according to the evaluation criteria, and was used as a measure of the color tone change by the average value of the color tone change by the fluorescent lamp irradiation and the color tone change by the high temperature treatment.

5: Almost no change 4: Slight color change is observed 3: Increase in color change is observed in part 2: Color change is observed in a substantial part 1: Increase in color change is remarkable Above, measurement and evaluation The results are shown in Table 1.

  From Table 1, the photothermographic material of the present invention has not only good color tone but also good sensitivity, maximum density and fog as compared with the comparison, and also oscillates when exposed using a laser scanning exposure machine. It can be seen that the sensitivity and maximum density of the output image are extremely stable with respect to wavelength variations.

Example 2
<< Preparation of PET support >>
Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) was obtained according to a conventional method. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to produce an unstretched film having a thickness of 175 μm after heat setting. 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. Then, after heat setting at 240 ° C. for 20 seconds, the film was 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 40 N / cm ² to obtain a roll having a thickness of 175 μm.

Next, both sides of the support were subjected to corona discharge treatment at room temperature at 20 m / min using a pisolid state corona treatment machine (Pillar, 6KVA model). 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.

(Preparation of undercoat support)
The following photosensitive layer side undercoat coating liquid formulation was applied to one side (photosensitive layer surface) of the PET support subjected to the corona discharge treatment with a wire bar so that the wet coating amount was 6.6 ml / m ² (per one side). Dry at 180 ° C. for 5 minutes, and then apply the following back surface side first layer coating solution to the back surface (back surface) with a wire bar so that the wet coating amount is 5.7 ml / m ^2. Dry for 5 minutes, and then apply the following back surface side second layer coating solution with a wire bar so that the wet coating amount is 7.7 ml / m ^2, and dry at 180 ° C. for 6 minutes to undercoat support Was made.

(Photosensitive layer side undercoat layer coating solution)
Takamatsu Yushi Co., Ltd., pesresin A-515GB (30% solution) 234 g
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5, 10% solution) 21.5 g
Polymer fine particles (manufactured by Soken Chemical Co., Ltd., MP-1000, average particle size 0.4 μm)
0.91g
744 ml of distilled water
(Back surface side first layer coating solution)
Styrene-butadiene copolymer latex (solid content 40% by mass, styrene / butadiene mass ratio = 68/32) 158 g
2,4-Dichloro-6-hydroxy-S-triazine sodium salt (8% aqueous solution)
20g
Sodium laurylbenzenesulfonate (1% aqueous solution) 10ml
854 ml of distilled water
(Back surface side second layer coating solution)
SnO ₂ / SbO (mass ratio, 9/1, average particle size 0.038 μm, 17% dispersion)
84g
Gelatin (10% aqueous solution) 89.2g
8.6 g made by Shin-Etsu Chemical Co., Ltd., Metroz TC-5 (2% aqueous solution)
0.01 g of polymer fine particles (MP-1000, manufactured by Soken Chemical Co., Ltd.)
Sodium dodecylbenzenesulfonate (1% aqueous solution) 10ml
NaOH (1%) 6ml
Proxel (ICI) 1ml
805 ml of distilled water
<Back side application>
On the back surface side of the undercoat support, the following back surface coating solution (antihalation layer coating solution) is applied so that the solid content coating amount of the solid fine particle dye is 0.04 g / m ^2, and the back surface protective layer coating solution. Was coated at the same time with a gelatin coating amount of 1.7 g / m ² and dried to prepare a back layer.

(Preparation of back surface coating solution)
Gelatin 17 g, polyacrylamide 9.6 g, solid precursor dispersion (a) 70 g of the following base precursor, 56 g of the following dye solid fine particle dispersion, monodisperse polymethyl methacrylate fine particles (average particle size 8 μm, particle size standard deviation 0.4) 1.5 g, benzoisothiazolinone 0.03 g, sodium polyethylene sulfonate 2.2 g, blue dye compound 14 0.2 g, yellow dye compound 15 3.9 g and water 844 ml are mixed to prepare a back surface coating solution. did.

<Preparation of Base Precursor Solid Fine Particle Dispersion (a)>
64 g of the base precursor compound 11, 28 g of diphenylsulfone and 10 g of surfactant Demol N manufactured by Kao Co., Ltd. were mixed with 220 ml of distilled water, and the mixture was mixed with a sand mill (1/4 Gallon Sand Grinder Mill, manufactured by IMEX Co., Ltd.). Using the resulting solution, beads were dispersed to obtain a solid fine particle dispersion (a) of a base precursor compound having an average particle size of 0.2 μm.

<Preparation of dye solid fine particle dispersion>
9.6 g of cyanine dye compound 13 and 5.8 g of sodium p-dodecylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was dispersed in beads using a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.). Thus, a dye solid fine particle dispersion having an average particle size of 0.2 μm was obtained.

(Preparation of back surface protective layer coating solution)
The container was kept at 40 ° C., 50 g of gelatin, 0.2 g of sodium polystyrenesulfonate, 2.4 g of N, N-ethylenebis (vinylsulfoneacetamide), 1 g of sodium tert-octylphenoxyethoxyethanesulfonate, 30 mg of benzoisothiazolinone , Fluorine-based surfactant (F-1: N-perfluorooctylsulfonyl-N-propylalanine potassium salt) 37 mg, fluorine-based surfactant (F-2: polyethylene glycol mono (N-perfluorooctylsulfonyl-N-) Propyl-2-aminoethyl) ether [ethylene oxide average polymerization degree 15]) 0.15 g, fluorosurfactant (F-3) 64 mg, fluorosurfactant (F-4) 32 mg, acrylic acid / ethyl acrylate Copolymer (copolymerization mass ratio 5/95) .8G, (manufactured by American Cyanamid Co.) Aerosol OT to give 0.6 g, 1.8 g as liquid paraffin of liquid paraffin emulsion, the water was mixed 950ml back surface protective layer coating solution.

<< Preparation of silver halide emulsion >>
While adding 3.1 ml of 1% potassium bromide solution to 1421 ml of distilled water, and further adding 3.5 ml of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin, the mixture was stirred in a stainless steel reaction vessel. Maintaining the liquid temperature at 30 ° C., distilled water was added to 22.22 g of silver nitrate to dilute to 95.4 ml, solution A, 15.3 g of potassium bromide and 0.8 g of potassium iodide in distilled water with a capacity 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% aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% aqueous solution of benzimidazole was further added. Further, a solution C obtained by diluting 51.86 g of silver nitrate to 317.5 ml and a solution D obtained by diluting 44.2 g of potassium bromide and 2.2 g of potassium iodide to a capacity of 400 ml with distilled water, 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 Solution C and 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 0.34% 1,2-benzisothiazolin-3-one in methanol was added, and after 40 minutes, spectral sensitizing dye A and spectral sensitization were added. A methanol solution having a molar ratio of dye B of 1: 1 was added in a total amount of 1.2 × 10 ⁻³ mol of sensitizing dye A and spectral sensitizing dye B per mol of silver, and the temperature was raised to 47 ° C. after 1 minute. . 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. 1.3 ml of a 0.8% methanol solution of N, N'-dihydroxy-N "-diethylmelamine was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4. Halogenation by adding 5.4 × 10 ⁻³ mol of 8 × 10 ⁻³ mol and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole to 1 mol of silver with methanol solution A silver emulsion 1 was prepared, and the grains in the prepared silver halide emulsion were silver iodobromide uniformly 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, and the {100} face ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of mixed emulsion A for coating solution >>
70% of silver halide emulsion 1, 15% of silver halide emulsion 2 and 15% of silver halide emulsion 3 are dissolved, and benzothiazolium iodide is dissolved in a 1% aqueous solution at 7 × 10 ⁻³ per mol of silver. Mole was added. 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.

<< Preparation of fatty acid silver dispersion >>
Henkel behenic acid (product name Edenor C22-85R) 87.6 kg, distilled water 423 L, 5 mol / L NaOH aqueous solution 49.2 L, tert-butanol 120 L were mixed and stirred at 75 ° C. for 1 hour to react. A sodium behenate solution was obtained. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of tert-butanol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution and the total amount of the silver nitrate aqueous solution were kept at a constant flow rate for 93 minutes and 15 seconds, respectively. Added over 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution is completed, only the sodium behenate solution is added for 14 minutes and 15 seconds. To be 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 for the sodium behenate solution was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying. When the morphology of the obtained silver behenate particles was evaluated by electron microscopic photography, it was a scaly crystal having an average aspect ratio of 5.2, an average sphere equivalent diameter of 0.52 μm, and a sphere equivalent diameter variation coefficient of 15%. .

19.3 kg of polyvinyl alcohol (PVA-217, manufactured by Kuraray Co., Ltd.) and water are added to a wet cake corresponding to a dry solid content of 260 kg, and the whole amount is made 1000 kg and slurried with a dissolver blade, and further a pipeline mixer (Mizuho) Industrial dispersion, PM-10 type). Next, the pre-dispersed stock solution was adjusted to a pressure of 12.6 kN / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) Three times of treatment was performed to obtain 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 reducing agent dispersion >>
16 kg of water was added to 10 kg of a 20% aqueous solution of 6.0 g × 10 ⁻³ / m ^{2 of} silver ion reducing agent (compound described in Table 2) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), Mix well to make a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal bead mill (IMM Co., Ltd., UVM-2) filled with zirconia beads having an average diameter of 0.5 mm for 3 hours 30 minutes, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% to obtain a reducing agent dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.42 μm and a maximum particle diameter of 2.0 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of dispersion of compound represented by formula (1) >>
75 g of water was added to 150 g of a 10% aqueous solution of the compound represented by the general formula (1) (compound and amount described in Table 2) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP-203), Mix well to make a slurry. This slurry was dispersed with a 0.5 mm zirconia bead and a sand mill (1/4 Gallon sand grinder mill, manufactured by IMEX Co., Ltd.) for 10 hours at a rotation speed of 1500 rpm to obtain a solid fine particle dispersion having a median diameter of 0.4 μm. Obtained. The obtained 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 dispersion of development accelerator-1 >>
75 g of water was added to 75 g of development accelerator-1 and 150 g of a 10% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP-203) and mixed well to obtain a slurry. Using a 0.5 mm zirconia bead and a sand mill (1/4 Gallon sand grinder mill, manufactured by AIMEX Co., Ltd.), this slurry was dispersed with beads at a rotation speed of 1500 rpm for 10 hours to obtain a solid fine particle dispersion having a median diameter of 0.35 μm. Obtained. The obtained 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 hydrogen bonding compound-2 dispersion >>
Add 10 kg of water to 10 kg of 10% aqueous solution of hydrogen bonding compound-2 (tri (4-tert-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) and mix well. To give a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal bead mill (IMM Co., Ltd., UVM-2) filled with zirconia beads having an average diameter of 0.5 mm for 3 hours 30 minutes, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 22% to obtain a hydrogen bonding compound-2 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.35 μm and a maximum particle diameter of 1.5 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.

<< Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (2-tribromomethanesulfonylnaphthalene), 10 kg of 20% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), and 0.4 kg of 20% aqueous solution of sodium triisopropylnaphthalenesulfonate Then, 16 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, dispersed for 5 hours in a horizontal bead 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 an organic polyhalogen compound concentration of 23.5% 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 0.36 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of organic polyhalogen compound-2 (tribromomethanesulfonylbenzene), 10 kg of 20% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), 0.4 kg of 20% aqueous solution of sodium triisopropylnaphthalenesulfonate, 14 kg of water was added and mixed well to make a slurry. This slurry was fed with a diaphragm pump, dispersed for 5 hours in a horizontal bead 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 an organic polyhalogen compound concentration of 26% 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 0.41 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 Phthalazine Compound-1 Solution >>
8 kg of modified polyvinyl alcohol (MP203, manufactured by Kuraray Co., Ltd.) was dissolved in 174.57 kg of water, then 3.15 kg of a 20% aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 (6-isopropylphthalazine). 14.28 kg of 70% aqueous solution was added to prepare a 5% solution of phthalazine compound-1.

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

<< Preparation of Pigment-1 Dispersion >>
C. I. Pigment Blue 60 (64 g) and Kao Corp. demole N (6.4 g) were added to 250 g of water and mixed well to prepare 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 for 25 hours with a disperser (1/4 Gallon sand grinder mill: manufactured by IMEX Co., Ltd.). Obtained. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<< Preparation of SBR Latex Liquid >>
An SBR latex with Tg = 23 ° C. was prepared as follows. Ammonium persulfate is used as a polymerization initiator, an anionic surfactant is used as an emulsifier, 70.5 parts by mass of styrene, 26.5 parts by mass of butadiene and 3 parts by mass of acrylic acid are emulsion-polymerized, and then aging is performed at 80 ° C. for 8 hours. went. Thereafter, the mixture was cooled to 40 ° C., adjusted to pH 7.0 with aqueous ammonia, and Sandet BL manufactured by Sanyo Chemical Co., Ltd. was further added to 0.22%. Next, 5% aqueous sodium hydroxide solution was added to adjust the pH to 8.3, and further adjusted to pH 8.4 with aqueous ammonia. The molar ratio of Na ⁺ ions and NH ₄ ⁺ ions used at this time was 1: 2.3. Further, 0.15 ml of a 7% aqueous solution of benzoisothiazoline non sodium salt was added to 1 kg of this liquid to prepare an SBR latex liquid.

SBR latex: -St (70.5 mol%) -Bu (26.5 mol%) -AA (3 mol%)-latex, Tg23 ° C
Average particle size 0.1 μm, concentration 43%, equilibrium moisture content 0.6% at 25 ° C. and relative humidity 60%, ion conductivity 4.2 mS / cm (measurement of ion conductivity is conducted by Toa Denpa Kogyo Co., Ltd.) CM-30S in total, latex stock solution (43%) measured at 25 ° C), pH 8.4
SBR latexes having different Tg were prepared in the same manner by appropriately changing the ratio of styrene and butadiene.

<< Preparation of emulsion layer (photosensitive layer) coating solution >>
1000 g of the fatty acid silver dispersion obtained above, 125 ml of water, 204 g of the reducing agent dispersion, a dispersion of the compound represented by the general formula (1) (type and amount are described in Table 2), 27 g of the pigment-1 dispersion, 82 g of organic polyhalogen compound-1 dispersion, 40 g of organic polyhalogen compound-2 dispersion, 173 g of phthalazine compound-1 solution, 1082 g of SBR latex (Tg: 20.5 ° C.) solution, and 9 g of mercapto compound-1 aqueous solution were sequentially added. Immediately before coating, 158 g of silver halide mixed emulsion A was added and mixed well, and the emulsion layer coating solution was directly fed to the coating die and coated. The viscosity of the emulsion layer coating solution was 40 mPa · s at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki. The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is 1500, 220, 70 at shear rates of 0.1, 1, 10, 100, and 1000 (1 / second), respectively. 40 and 20 mPa · s.

<Preparation of emulsion surface intermediate layer coating solution>
772 g of 10% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 5.3 g of 20% dispersion of pigment, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio) 64/9/20/5/2) 226 g of 27.5% latex 22.5 ml of aerosol OT (manufactured by American Cyanamid), 10.5 ml of 20% aqueous solution of diammonium phthalate, Water was added so that the total amount would be 880 g, and the pH was adjusted with NaOH so as to be 7.5 to obtain an intermediate layer coating solution, which was fed to the coating die so as to be 10 ml / m ² . The viscosity of the coating solution was 21 mPa · s at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

<< Preparation of emulsion surface protective layer first layer coating solution >>
Inert gelatin (64 g) is dissolved in water, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5/2) latex 27.5% solution 80 g, phthalate 23 ml of 10% methanol solution of acid, 23 ml of 10% aqueous solution of 4-methylphthalic acid, 28 ml of sulfuric acid having a concentration of 0.5 mol / L, 5 ml of 5% aqueous solution of aerosol OT (American Cyanamid Co., Ltd.), 0% phenoxyethanol 0.5 g and 0.1 g of benzoisothiazolinone were added, and water was added so that the total amount became 750 g, and 26 ml of 4% chromium alum was mixed with a static mixer immediately before coating to 18.6 ml / m. ^The solution was fed to the coating die so as to be ² . The viscosity of the coating solution was 17 mPa · s at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

<< Preparation of photothermographic material >>
On the surface opposite to the coated back surface, the emulsion layer, the intermediate layer, the protective layer first layer, and the protective layer second layer are coated simultaneously in the order of the undercoat surface by the slide bead coating method, and photothermographic A sample of material was made. At this time, the emulsion layer and the intermediate layer were adjusted to 31 ° C., the protective layer first layer was adjusted to 36 ° C., and the protective layer first layer was adjusted to 37 ° C. The coating amount (g / m ² ) of each compound in the emulsion layer is as follows.

Silver behenate 6.19
Silver ion reducing agent (types listed in Table 2) 6.0 × 10 ⁻³
Compound represented by general formula (1) (type and amount are listed in Table 2)
Pigment (CI Pigment Blue 60) 0.032
Polyhalogen compound-1 0.46
Polyhalogen compound-2 0.25
Phthalazine Compound-1 0.21
SBR latex 11.1
Mercapto Compound-1 0.002
Silver halide (as Ag) 0.145
The coating and drying conditions are as follows. The coating speed was 160 m / min, the gap between the coating die tip and the support was 0.10 to 0.30 mm, and the pressure in the decompression chamber was set 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating. In the subsequent chilling zone, after cooling the coating solution with a wind at a dry bulb temperature of 10 to 20 ° C., it is transported in a non-contact type, and is dried at a dry bulb temperature of 23 to 45 ° C. It dried with the dry wind of the wet bulb temperature 15-21 degreeC. After drying, the humidity was adjusted at 25 ° C. and a relative humidity of 40 to 60%, and then the film surface was heated to 70 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 photosensitive layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.

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

<Evaluation of photographic performance>
The photosensitive material was exposed with a Fuji Medical Dry Laser Imager FM-DP L (mounted with a 660 nm semiconductor laser having a maximum output of 60 mW (IIIB)). After exposure, the FM-DPL thermal development unit is remodeled and thermally developed (total of 24 seconds with 4 panel heaters set at 112 ° C-119 ° C-121 ° C-121 ° C = standard development time is 24 seconds) did. The image obtained by exposure with each wavelength is subjected to density measurement with a Macbeth densitometer (TD-904), and a characteristic curve having a horizontal axis (exposure amount) and a vertical axis (image density) is created. Also, the reciprocal of the ratio of the exposure amount required to give a high density of 1.0 is defined as sensitivity, and is expressed as a relative value where the sensitivity of the sample 201 in Table 2 is 100. Further, the minimum density (fogging) was measured.

<Evaluation of image color tone>
The color tone of the obtained image was visually observed and evaluated in five stages based on the following criteria. Practically, it is preferably rank 4 or higher.

5: Cold black tone does not feel red at all. 4: Cold black tone does not feel red at all. 3: Partially slightly reddish. 2: Partially slightly reddish. 1: At first glance reddish. <Image preservation>
(Minimum density area image storage)
Each of the heat-developed samples prepared in the same manner as the above-described sensitivity, fog, and maximum density measurement methods was subjected to a commercially available white fluorescent lamp with an illuminance of 500 lux on the sample surface in an environment of 45 ° C. and 55% RH. And then irradiated continuously for 3 days. Measure the minimum density (D2) of the fluorescent lamp irradiated sample and the minimum density (D1) of the fluorescent lamp unirradiated sample, calculate the minimum density change rate (%) from the following formula, and save this in the image of the minimum density part A measure of gender. The closer the value is to 100, the better.

Minimum density change rate = D2 / D1 x 100 (%)
(Image storability of the highest density part)
Each of the heat-developed samples prepared in the same manner as the above sensitivity, fog, and maximum density measurement methods was left in an environment of 25 ° C. and 45 ° C. for 3 days, and then the change in the maximum density was measured. The rate of change in image density was measured by the equation, and this was used as a measure of image preservation at the highest density part. The closer the value is to 100, the better.

Image density change rate = maximum density of sample stored at 45 ° C./maximum density of sample stored at 25 ° C. × 100 (%)
(Color change)
For samples prepared by evaluation of image storability at the minimum density area, the change in color tone by fluorescent lamp irradiation, and for samples prepared by evaluation of image storability at the maximum density area, the color tone change by high-temperature (45 ° C) treatment is as follows: It was obtained in five stages according to the evaluation criteria, and was used as a measure of the color tone change by the average value of the color tone change by the fluorescent lamp irradiation and the color tone change by the high temperature treatment.

5: Almost no change 4: Slight color change is observed 3: Increase in color change is observed in part 2: Color change is observed in a substantial part 1: Increase in color change is remarkable Above, measurement and evaluation Table 2 shows the results.

  From the results in Table 2, it can be seen that the photothermographic material of the present invention has higher sensitivity, lower fog and good color tone than the comparative sample. Further, it can be seen that the image storage stability is much superior to that of the comparative example.

Claims (6)

The photothermographic material having an image forming layer containing a non-photosensitive organic silver salt, silver halide, silver ion reducing agent and binder on the support contains a compound represented by the following general formula (1). A photothermographic material characterized by the above.

(In the general formula (1), W represents a substituent other than a hydroxy group, a hydrogen atom or a halogen atom. R ₁ , R ₂ , R ₃ , R ₄ , R ₆ and R ₇ are a hydrogen atom, a substituent or a halogen atom. .X representing the atom is O, is .R ₅ representing S or N-R ₅ represents a hydrogen atom or a substituent.) 2. The heat according to claim 1, wherein in the general formula (1), W represents a hydrogen atom, an aliphatic group, an alkoxy group, an amino group, a sulfonamide group, an acylamino group, an acyloxy group, or a carbamoyloxy group. Development photosensitive material. 3. The photothermographic material according to claim 1, wherein in the general formula (1), at least one of R ₆ and R ₇ represents an aliphatic group, an aromatic group, or a heterocyclic group. The photothermographic material according to claim 1, wherein, in the general formula (1), R ₁ and R ₂ represent an aliphatic group or an alkoxy group. The photothermographic material according to claim 1, wherein the silver ion reducing agent is represented by the following general formula (R).

(In the general formula (R), R ₁₁ and R ₁₂ each independently represents a hydrogen atom, an aliphatic group or an aromatic group. R ₁₃ and R ₁₄ each independently represent a hydrogen atom, an aliphatic group, an aromatic group or Represents a heterocyclic group, Q represents a substitutable group on the benzene ring, and n represents an integer of 0 to 2. When Q is plural, each Q may be the same or different. The addition ratio (molar ratio) of the compound represented by the general formula (1) and the silver ion reducing agent is 0.001 to 0.15, according to any one of claims 1 to 5. The photothermographic material according to the description.