JP2006330257A - 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 image storage stability. <P>SOLUTION: The heat developable photosensitive material has on a support a photosensitive 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 R<SB>1</SB>-R<SB>4</SB>each independently represent H, a substituent or halogen; X represents O, S or N-R<SB>5</SB>, R<SB>5</SB>represents H or a substituent; and R<SB>6</SB>and R<SB>7</SB>each represent H, a substituent or halogen, provided that R<SB>6</SB>and R<SB>7</SB>are not simultaneously phenyl. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photothermographic material having a photosensitive layer containing a non-photosensitive organic silver salt, a silver halide, a silver ion reducing agent and a binder on a support.

  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. As this technique, for example, U.S. Pat. Nos. 3,152,904 and 3,487,075 and D.C. The method described in “Dry Silver Photographic Materials” by Morgan (Handbook of Imaging Materials, Marcel Dekker, Inc., p. 48, 1991) is well known. These photosensitive materials are called photothermographic materials because they are usually developed at a temperature of 80 ° C. or higher.

  Compared to conventional photosensitive materials that are processed by liquid, the photothermographic material contains a much larger number of types of chemical substances and the amount added, so the thickness of the photosensitive layer and non-photosensitive layer increases accordingly. Tend to. As a result, the coating process or the drying process at the time of manufacturing the light-sensitive material requires a lot of time and has the disadvantage that the productivity is lowered.

  In general, it is widely known that reducing the amount of silver in a light-sensitive material is effective in reducing the film thickness. However, mere reduction of the amount of silver is not preferable because it causes a decrease in image density. In order to reduce the amount of silver 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 “contagious development” using a nucleating agent has been established for photosensitive materials for printing (for example, Patent Document 1, 2).

  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 the above-mentioned colorant or the like, but the color tone control is not sufficient, and improvement is desired. As a technique for improving this defect, a combination of a specific reducing agent and a specific compound has been disclosed (for example, see Patent Documents 3 and 4), but the improvement effect is not sufficient, and the concentration during storage is low. There were serious problems such as being easy to change, and further improvements were required.

A technique using a leuco color former capable of forming a hydrogen bond in the molecule for the purpose of improving the color tone is known (for example, see Patent Document 5), but its effect is insufficient. In addition, imidazole leuco dye is widely used as a hydrogen peroxide quantification reagent (see, for example, Patent Document 6), but there are few examples of adding it to a photosensitive material. Although a technique using an imidazole leuco dye in a photothermographic material is disclosed (for example, see Patent Document 7), it is merely added as a reducing agent, and both sensitivity and density are insufficient.
Japanese National Patent Publication No. 10-512061 Japanese National Patent Publication No. 11-511571 JP 2002-169240 A JP 2002-236334 A JP-A-2005-3841 Japanese Patent Publication No. 7-45477 US Pat. No. 3,985,565

  SUMMARY OF THE INVENTION An object of the present invention is to provide a photothermographic material having a maximum density and sensitivity, a low fog, a cool black tone with good silver tone, and excellent image storage stability. There is to do.

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

(Claim 1)
A photothermographic material having a photosensitive layer containing a non-photosensitive organic silver salt, silver halide, silver ion reducing agent and binder on a support, containing a compound represented by the following general formula (1): A heat-developable photosensitive material.

In (formula _{(1), R 1, R} 2, R 3 and R ₄ are each independently a hydrogen atom, .X representing a substituent group or a halogen atom O, .R ₅ representing S or N-R ₅ is Represents a hydrogen atom or a substituent, R ₆ and R ₇ represent a hydrogen atom, a substituent or a halogen atom, but R ₆ and R ₇ are not a phenyl group at the same time.)
(Claim 2)
2. The photothermographic material according to claim 1, wherein in the general formula (1), one of R ₆ and R ₇ is a phenyl group.

(Claim 3)
3. The photothermographic material according to claim 2, wherein, in the general formula (1), the other of R ₆ and R ₇ which is not a phenyl group is an alkyl group.

(Claim 4)
The photothermographic material according to claim 1, wherein, in the general formula (1), R ₁ and R ₂ are represented by 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 represent 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 of the compound represented by the general formula (1) to the silver ion reducing agent (mol number of the compound represented by general formula (1) / mol number of the silver ion reducing agent) is 0.001 to 0.00. The photothermographic material according to claim 1, wherein the photothermographic material is 15.

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

  Details of the present invention will be described below.

  The present invention is characterized in that the imidazole leuco dye represented by the general formula (1) is used as a color tone adjusting agent in a photothermographic material.

  In the present invention, the compound represented by the general formula (1) is used for the photothermographic material. In the photothermographic material of the present invention, the color tone of the image is a preferable cool black tone, and the color tone deterioration or the like in storage of a silver image against heat and light after heat development is unexpectedly suppressed.

In the general formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represents 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. R ₆ and R ₇ represent a hydrogen atom, a substituent or a halogen atom, but R ₆ and R ₇ are not simultaneously phenyl groups.

Specific examples of the substituent represented by R ₁ , R ₂ , R ₃ , R ₄ and R ₅ include an alkyl group (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Group), cycloalkyl group (cyclohexyl group, cyclopentyl group etc.), alkenyl group, cycloalkenyl group, alkynyl group (propargyl group etc.), glycidyl group, acrylate group, methacrylate group, aromatic group (phenyl group, naphthyl group, Anthracenyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, triphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group Etc.), alkoxy group (methoxy group, ethoxy group, propylo group) Xy 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, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenyl group) Nosulfonyl 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, cyclohexylamino) Carbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), acylamino group (acetylamino group, benzoylamino group, methylureido group, etc.), amide group (acetamide group, Lopionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), sulfonamide group (For example, methylsulfonamide group, octylsulfonamide group, phenylsulfonamide group, naphthylsulfonamide 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 and the like. Further, these groups may be further substituted with these groups.

  However, in this specification, the “phenyl group” means a monocyclic phenyl group which is unsubstituted or substituted with an arbitrary substituent, and a compound in which the phenyl group is condensed (for example, naphthyl group, anthracenyl group, etc.) Is not included.

Examples of the halogen atom represented by R ₁ , R ₂ , R ₃ , R ₄ and R ₅ include a chlorine atom, a bromine atom, an iodine atom and a fluorine atom.

R ₁ and R ₂ are preferably alkyl groups, cycloalkyl groups, alkoxy groups, aryloxy groups, more preferably alkyl groups, cycloalkyl groups, or alkoxy groups, still more preferably secondary or tertiary alkyl groups, alkoxy groups. It is. 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.

X represents O, S or N—R ₅ . X is preferably N—R ₅ . R ₅ is preferably a hydrogen atom, an alkyl group, an aromatic 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. .

R ₆ and R ₇ are preferably an alkyl group, a cycloalkyl group, an aromatic group, a heterocyclic group, more preferably one of R ₆ and R ₇ is a phenyl group, and the other is an alkyl 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 of 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.

  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 represent a hydrogen atom, an aliphatic group, or an aromatic group. R ₁₃ and R ₁₄ each independently represents 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 present specification, the “aliphatic group” means a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, and aralkyl group, respectively.

Specific examples of the aliphatic group represented by R ₁₁ and R ₁₂ include methyl group, ethyl group, propyl group, isopropyl group, normal butyl group, tert-butyl group, pentyl group, hexyl group, decyl group, dodecyl group. , Pentadecyl group, vinyl group, allyl group, ethynyl group, propargyl group, cyclopropyl group, cyclobutyl group, cyclobutenyl group, cyclopentyl group, cyclopentenyl group, cyclopentadienyl group, cyclohexyl group, cyclohexenyl group, cyclohexadienyl group , Cycloheptyl, cycloheptynyl, cycloheptadienyl, cyclooctanyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, cyclononanyl, cyclononenyl, cyclononadienyl, cyclononatrienyl Cyclodecanyl group Shikurodekeniru group, a cycloalkyl decadienyl 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 R ₁₁ and R ₁₂ may be a single ring or a condensed ring, and examples thereof include phenyl, naphthyl, anthracenyl, phenanthrenyl, naphthacenyl, triphenylenyl and the like. These rings may have various substituents at any position, and as a preferable substituent, a linear or branched alkyl group (preferably having 1 to 20 carbon atoms, for example, methyl, ethyl, propyl, isopropyl). , Dodecyl, etc.), alkoxy groups (preferably having 1 to 20 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, dodecyloxy, etc.), aliphatic acylamino groups (preferably having an alkyl group having 1 to 21 carbon atoms) For example, an acetylamino group, a heptylamino group, etc.) and an aromatic acylamino group.

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, or a cyclohexyl group. It is.

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 . Specific 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. And aromatic heterocyclic groups such as a group, 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, and examples of the substituent include the above-described substituents on the ring. R ₁₃ is preferably an alkyl group or a cycloalkyl group, and 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.

  As a general synthesis method of the compound represented by the general formula (R), preferably 2 equivalents of phenol and 1 equivalent of aldehyde are dissolved or suspended in a solvent-free or appropriate organic solvent, By adding an acid or alkali, and preferably reacting at a temperature of −20 to 180 ° C. for 0.5 to 60 hours, the desired compound represented by the general formula (R) can be obtained in good yield. .

  The organic solvent is preferably a hydrocarbon organic solvent, and specific examples include benzene, toluene, xylene, dichloromethane, chloroform and the like. 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, and sodium methylate are preferably used. As a catalyst amount, it is preferable to use 0.001-1.5 equivalent with respect to a 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 of general formula (R) is shown, this invention is not limited to these.

  The addition ratio of the compound represented by the general formula (1) and the silver ion reducing agent (the number of moles of the compound represented by the general formula (1) / the number of moles of the silver ion reducing agent) in the present invention is preferably 0. It is 001-0.15, More preferably, it is 0.001-0.10.

  Photosensitive silver halide grains (also simply referred to as silver halide grains) used in the photothermographic material of the present invention (also referred to simply as the light-sensitive material of the present invention) will be described. The photosensitive silver halide grains in the present invention can inherently absorb light as an intrinsic property of silver halide crystals, or artificially generate visible light or infrared light by a physicochemical method. Physicochemical changes 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. Refers to silver halide crystal grains that have been processed and produced so that can occur.

(Photosensitive silver halide grains)
The photosensitive silver halide grains themselves according to the present invention are P.I. Chifie et Physique Photographic (published by Paul Montel, 1967) by Glafkides. 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 of an acidic method, a neutral method, an ammonia method, and the like 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 formation of nucleus (seed grain) and grain growth is separated. The method of performing may be used. The controlled double jet method in which the particle formation is controlled by controlling the pAg, pH, etc., which are particle formation conditions, 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 photosensitive 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. As a value when particles less than 0.02 μm are excluded from measurement, 0.035 μm or more and 0.055 μm or less are preferable. The grain size referred to 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 monodispersion mentioned here 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.

Variation coefficient 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.

  When tabular silver halide grains are used, the average aspect ratio is preferably 1.5 or more and 100 or less, more preferably 2 or more and 50 or less. 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 limitation on the crystal habit on the outer 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 proportion of the [100] face on the outer surface of the silver halide grain is preferably high, and this ratio is 50 % Or more, more preferably 70% or more, and particularly preferably 80% or more. The ratio of the Miller index [100] plane is calculated by using the adsorption dependency between 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 forming the grains, 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 an ammonium group substituted with a hydrogen atom, an alkali metal atom, an ammonium group, or an alkyl group having 5 or less carbon atoms. And 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 supports the step of producing a gelatin aqueous solution, the step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, and the emulsion when producing a silver halide photographic light-sensitive material. It has been preferably used as an antifoaming agent for remarkable foaming when the emulsion raw material is stirred or moved, such as a step of coating on the body. 44-9497. 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. Further, it is preferably present for a time of at least 50% of the nucleation step, more preferably for a time of 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 rise pattern (for example, the temperature at the start of nucleation is 25 ° C. and gradually increases during nucleation) Even if the temperature is raised and the temperature at the end of nucleation is 40 ° C.) and vice versa, the temperature is preferably controlled within the above temperature range.

The concentration of the aqueous silver salt solution and aqueous halide solution used for nucleation is preferably 3.5 mol / L or less, and more preferably used in a low concentration range of 0.01 to 2.5 mol / L. 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 close to a reducible silver source (organic silver salt). It is preferable to arrange them as follows.

  Since the silver halide according to the present invention is prepared in advance and added to a solution for preparing organic silver salt grains, the silver halide preparation step and the organic silver salt grain preparation step can be handled separately. Although preferable in terms of production control, as described in British Patent No. 1,447,454, a halogen component such as a halide ion is allowed to coexist with an organic silver salt-forming component when preparing organic silver salt particles. It is also possible to produce organic silver salt particles almost simultaneously with the implantation of silver ions. It is also possible to prepare silver halide grains by converting a halogen-containing compound to an organic silver salt and converting the organic silver salt. That is, a silver halide forming component is allowed to act on a solution or dispersion of an organic silver salt prepared in advance or a sheet material containing the organic silver salt to convert a part of the organic silver salt into photosensitive silver halide. You can also.

  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-53-27027 and No. 53-25420. Metal halides, 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 -Bromine-2-methylpropane, etc. N-halogen compounds such as genated hydrocarbons, N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, etc., for example, triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2 -Bromoethanol, dichlorobenzophenone, etc.

  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 a halogen ion. Moreover, you may use together the silver halide grain manufactured by converting a part of organic silver salt into the silver halide prepared separately.

  These silver halide grains, both separately prepared silver halide grains and silver halide grains obtained by conversion of organic silver salts, are 0.001 mol to 0.7 mol, preferably 0.03 mol to 0.00 mol, with respect to 1 mol of organic silver salt. It is preferable to use 5 mol.

  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 preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻² mol, and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ mol 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, and 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 of adding an aqueous solution or a metal compound and an aqueous solution in which NaCl and KCl are dissolved together to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or simultaneously mixing a silver salt solution and a halide solution. When adding a third aqueous solution, a method of preparing silver halide grains by a method of simultaneous mixing of three liquids, a method of adding an aqueous solution of a required amount of a metal compound to the reaction vessel during grain formation, or silver halide There is a method of adding and dissolving another silver halide grain previously doped with metal ions or complex ions at the time of preparation. 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 photosensitive silver halide grains can be desalted by a known desalting method such as noodle method, flocculation method, ultrafiltration method, electrodialysis method, etc., 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, and is a non-photosensitive salt of an organic acid containing silver ions. 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 above organic silver salts, 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 high-concentration and high-contrast silver image. It is preferable to prepare by mixing a silver ion solution with a carboxylic acid mixture.

  The aliphatic carboxylic acid silver salt compound is obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and is described in the normal mixing method, the back mixing method, the simultaneous mixing method, and JP-A-9-127643. The controlled double jet method as described above is preferably used. For example, an alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate), and then a 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 organic silver salt according to the present invention, the average equivalent circle diameter is preferably 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. From the viewpoint of improving the storability of the obtained image, it is preferable to adjust the average thickness to 0.005 to 0.07 μm, particularly preferably the average equivalent circle diameter. Is 0.2 to 0.5 μm, and the average thickness is adjusted to a range of 0.01 to 0.05 μm.

  To obtain the average equivalent circle diameter, the dispersed organic silver salt is diluted and dispersed on a grid with a carbon support film, and taken with a transmission electron microscope (manufactured by JEOL, 2000FX type), directly at a magnification of 5000 times. went. The negative is captured as a digital image with a scanner, and 300 or more particle diameters (equivalent circle diameters) are measured using appropriate image processing software, and the average particle diameter 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 ultrathin slice was supported on a copper mesh, transferred onto a carbon film that had been made hydrophilic by glow discharge, and cooled to −130 ° C. or lower with liquid nitrogen, using a transmission electron microscope (hereinafter referred to as TEM). A bright field image is observed at a magnification of 5,000 to 40,000, 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.

  It is preferable to use a carbon film supported by an organic film such as very thin collodion or form bar, and more preferably formed on a rock salt substrate by dissolving and removing the substrate, or the organic film is an organic solvent, It is a carbon-only film obtained by ion etching. The acceleration voltage of TEM 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 Japan Electron Microscopy Society Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Japan Electron Microscopy Society Kanto Branch / Electron Microscope Biological Samples” "Manufacturing method" (Maruzen) can be referred to respectively.

  A TEM image recorded on an appropriate medium is preferably decomposed into at least 1024 pixels × 1024 pixels, preferably 2048 pixels × 2048 pixels or more, and image processing by a computer is performed. 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, or the like is 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 thicknesses of the extracted organic silver salt particles are manually measured with appropriate software, and an average value is obtained.

  The method for obtaining the organic 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 is kept good. It is effective to optimize the ratio of the organic acid to the soap and the ratio of the silver nitrate that reacts with the soap.

  Flat organic silver salt particles used in the present invention (meaning organic silver salt particles having an average equivalent circle diameter of 0.05 μm or more and 0.8 μm or less and an average thickness of 0.005 μm or more and 0.07 μm or less) ) Is preferably pre-dispersed with a binder, a surfactant or the like, if necessary, and then dispersed and ground 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 agitation mill, an attritor, and other basket mills can be used, and a wall as a high-pressure homogenizer. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are collided at a high speed after dividing the liquid, and a type in which a thin orifice is passed.

Examples of the ceramic 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 ( strontium _{titanate), 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 when dispersing the flat organic silver salt particles used in the present invention, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond is used as the material of the member in contact with the organic silver salt particles. Preferably, zirconia is preferably used. When the above dispersion is performed, the binder concentration is preferably added in an amount of 0.1 to 10% of the mass of the aliphatic silver carboxylate, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion through the main dispersion. Further, as preferable operating conditions for the present dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, preferable operating conditions are 29.42 to 98.06 MPa, and the number of operations is preferably 2 times or more. Further, when the media disperser is used as a dispersing means, a preferable condition is that the peripheral speed is 6 m / sec to 13 m / sec.

  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 and monodispersing than when it is produced under the condition of not coexisting. 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, moloctic 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 silver aliphatic carboxylate.

  Glycosides such as glucoside, galactoside, 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, 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 charging step, and monodispersed by increasing the stirring efficiency, and Reduce the particle 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 out before and after the development process. That is, it contains a large amount of photosensitive silver halide, organic silver salt and reducing agent that may cause generation of silver (baked-out silver). For this reason, in order to maintain the storage stability not only before development but also after development, the photothermographic material is required to have high antifogging and image stabilization techniques. In addition to the aromatic heterocyclic compounds to be suppressed, mercury compounds such as mercury acetate having the function of oxidizing and extinguishing fog nuclei have been used as very effective storage stabilizers. 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 invention will be described below.

  In the photothermographic material of the present invention, a reducing agent such as bisphenols is mainly used as the reducing agent, as will be described later. By generating active species capable of extracting these hydrogens, the reducing agent is generated. It is preferable that the compound which can inactivate 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, as a compound that generates these free radicals, a carbocyclic or heterocyclic ring is used so that the generated free radicals are stable enough to react with a reducing agent and be inactivated for a sufficient period of time to be inactivated. Those having an aromatic group of the formula are preferred.

  Typical 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 the specifications of 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 ¹¹ , R ¹² and R ¹³ (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.), an acylamino group, a sulfonylamino group, an acyloxy group (for example, Setokishi 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 ¹⁴ 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 ¹³ is a sulfo group or a carboxyl group, W is 0 and R ¹⁴ is O ⁻ . In addition, any of R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring.

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

^{Wherein, R 21, R 22, R} 23, R 24, 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 . is there. 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 organic 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 a halogen atom. Can be used in combination with compounds that release non-active species. 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 general formula [4], Q ₂ represents an aryl group or a heterocyclic group. X ₁₁ , X ₁₂ and X ₁₃ 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.), and more Preferably they are a phenyl group and a naphthyl group, More preferably, it 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, which 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, and 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- to 6-membered aromatic heterocyclic group optionally having a condensed ring containing a nitrogen atom, and particularly preferably 5 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 ₁₁ , X ₁₂ and X ₁₃ 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, a haloalkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group or a sulfonyl group (an alkylsulfonyl group or an arylsulfonyl group), more preferably a halogen atom or a trihalomethyl group, A halogen atom is preferred. 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 represents —C (═O) —, —SO— or —SO ₂ —, among which —SO ₂ — is preferably used.

  The amount of these compounds added is preferably within a range in which the increase in printout silver due to the formation of silver halide does not cause a problem, and is at most 150% or less, more preferably 100% in terms of the ratio to the compound that does not generate the active halogen radical. % Or less is preferable.

  In addition to the above compound, 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 if it is a compound which can produce | generate, the compound from which an antifogging mechanism differs may be sufficient. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, 3,874,946, 4,756,999, JP, Examples thereof include compounds described in JP-A-59-57234, JP-A-9-288328, and JP-A-9-90550. Still other antifoggants include compounds disclosed in US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981 and 631,176. Is mentioned.

  In the present invention, a known reducing agent can be used as the silver ion reducing agent, but a bisphenol derivative represented by the general formula (R) is preferable.

  The amount of the silver ion reducing agent used in the photothermographic material of the invention varies depending on the type of organic silver salt, reducing agent, and other additives, but generally 0.05 mol to 1 mol per mol of organic silver salt. 10 mol, preferably 0.1 mol to 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 photosensitive silver halide and organic silver salt grains and a solvent immediately before coating, because photographic performance fluctuation due to stagnation time is small. is there.

  The photosensitive silver halide according to the present invention can be chemically sensitized. For example, by using a compound that releases chalcogen such as sulfur or a noble metal compound that releases noble metal ions such as gold ions by the methods described in JP-A Nos. 2001-249428 and 2001-249426, A chemical sensitization center (chemical sensitization nucleus) can be formed and imparted. 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 are 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 an organic sensitizer varies depending on the chalcogen compound used, silver halide grains, reaction environment for chemical sensitization, etc., but is 10 ⁻⁸ to 10 ⁻² mol per mol of silver halide. Is preferable, and more preferably 10 ⁻⁷ to 10 ⁻³ mol is used. The chemical sensitization environment is not particularly limited, but in the presence of a compound capable of annihilating or reducing the size of silver chalcogenide or silver nuclei on photosensitive silver halide grains, and in particular oxidizing silver nuclei. It is preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the presence of an oxidant, and as the sensitization condition, pAg is preferably 6 to 11, and more preferably 7 to 10 The pH is preferably 4 to 10, more preferably 5 to 8, and the temperature is preferably 30 ° C. or lower for sensitization.

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

  In addition, chemical sensitization using these organic sensitizers is preferably performed in the presence of a heteroatom-containing compound having adsorptivity to 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. The spectral sensitizing dye will be described later, and preferred examples of the heteroatom-containing compound having an 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.

  Of these, an azaindene ring is preferable, and an azaindene compound having a hydroxyl group as a substituent, for example, a hydroxytriazaindene, tetrahydroxyazaindene, hydroxypentaazaindene compound, or the like is 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. You may have.

The addition amount of these heterocyclic compounds 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 mol per mol of silver halide. It is the range of ^-1 mol, Preferably it is the range of 10 < ^-4 > mol-10 < ^-1 > mol.

  The photosensitive 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 photosensitive 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 Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242, 63-15245, U.S. Pat. No. 4,639, No. 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). Has been. 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, for example, 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 above basic nucleus. 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 red disclosed in the specifications of US Pat. Nos. 4,536,473, 4,515,888, and 4,959,294. And an external spectral sensitizing dye. 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, The Chemistry of Heterocyclic Compounds, Volume 18 by The FM Hammer, The Cyanine Dies and Related Compounds (A. Weissberger ed. The method can be synthesized by referring to the method.

  These infrared sensitizing dyes may be added at any time after silver halide preparation. For example, silver halide grains or silver halide grains in a so-called solid dispersion state added to a solvent or dispersed in a fine particle form. / Can be added to a photosensitive emulsion containing organic 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-described spectral sensitizing dyes may be used alone, or a combination thereof may be used, and the combination of sensitizing dyes is often used for the purpose of supersensitization.

  The emulsion containing the photosensitive silver halide and organic silver salt used in the photothermographic material of the present invention is a sensitizing dye and a dye that does not have spectral sensitizing action itself or a substance that does not substantially absorb visible light. In addition, a substance exhibiting 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, No. 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. A group mercapto compound or a mercapto derivative compound is 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 above mercapto compound when contained in a dispersion of an organic 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 includes, for example, a halogen atom (for example, Cl, Br, I), a hydroxyl group, an amino group, a carboxyl group, and 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, a compound represented by the following general formula [5] and a macrocyclic compound can be used as the supersensitizer.

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. M ₃₁ represents an ion necessary for canceling the charge in the molecule, and k ₃₁ represents the number of ions necessary for canceling 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), an alkenyl group (preferably 2-20 carbons, more preferably 2-16, still more preferably 2-12), an alkynyl group (preferably 2-20 carbons, more preferably). 2 to 16, more preferably 2 to 12), and may have a substituent. For example, the aliphatic hydrocarbon group may be a linear, branched or cyclic alkyl group (preferably having a carbon number of 1 to 20, more preferably 1-16, still more preferably 1-12, alkenyl group (preferably 2-20 carbon atoms, more preferably 2-16, still more preferably 2-12), alkynyl group (preferably carbon) 2-20, more preferably 2-16, still more preferably 2-12), and examples of the aryl group include monocyclic or condensed aryl groups having 6 to 20 carbon atoms (for example, phenyl, naphthyl, etc.). , Preferably phenyl), and as the heterocyclic group, 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 heterocyclic ring in these groups may be a single ring or may form a condensed ring with other rings. 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). C2-C12, Especially preferably, it is C2-C8, for example, a vinyl group, an allyl group, 2-butenyl group, 3-pentenyl group etc. are mentioned. A quinyl 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 a propargyl group and a 3-pentynyl group), an 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, and dimethylamino. Group, diethylamino group, diphenylamino group, dibenzylamino group, etc.), imino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 18 carbon atoms, Preferably it is C1-C12, for example, a methylimino group, an ethylimino group, a propylimino group, a phenylimino group, etc.) alkoxy group (preferably C1-C20, more preferably C1-C12, especially preferably C1-C8, for example, a methoxy group, an ethoxy group, a butoxy group, etc.), an aryloxy group (preferably C6-C20, more preferably C6-C16, especially preferably C6-C12). 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 2 carbon atoms). 16, particularly preferably 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 7-10 carbon atoms, for example, phenyloxycarbonyl group, etc., acyloxy groups (preferably 1-20 carbon atoms, more preferably 1-16 carbon atoms, particularly preferably 1-10 carbon atoms, for example, acetoxy Group, benzoyloxy group and the like), 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 and benzoylamino group), Alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably A prime number of 2 to 12, for example, methoxycarbonylamino and the like, an aryloxycarbonylamino group (preferably having a carbon number of 7 to 20, more preferably a carbon number of 7 to 16, particularly preferably a carbon number of 7 to 12, Phenyloxycarbonylamino, etc.), 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.), a sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, phenyl) Sulfamoyl group, etc.), carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably Or a carbon number of 1 to 16, particularly preferably a carbon number of 1 to 12. For example, a carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group, or the like, an alkylthio group (preferably having a carbon number of 1 to 20, more preferably Has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, for example, methylthio group, ethylthio group and the like, and arylthio group (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably C6-C12, for example, phenylthio group, etc., sulfonyl group (preferably C1-C20, more preferably C1-C16, particularly preferably C1-C12, for example, methanesulfonyl Group, tosyl group, etc.), sulfinyl group (preferably 1-20 carbon atoms, more preferably 1-16 carbon atoms, particularly preferred) Or having 1 to 12 carbon atoms, and 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 A 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), a hydroxyl group, a 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, pi Lysyl, and 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 A Arylamino 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. The amidino group includes those having a substituent. Examples of the substituent include an alkyl group (each group such as methyl, ethyl, pyridylmethyl, benzyl, phenethyl, carboxybenzyl, aminophenylmethyl), an aryl group (phenyl). , P-tolyl, naphthyl, o-aminophenyl, o-methoxyphenyl and the like), a heterocyclic group (2-thiazolyl, 2-pyridyl, 3-pyridyl, 2-furyl, 3-furyl, 2-thieno, 2-imidazolyl, benzothiazolyl, carbazolyl and the like) 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. , 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 T _31. The preferred ranges are 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 those mentioned as examples of the aliphatic hydrocarbon group, aryl group and heterocyclic group in T ₃₁ . The preferred ranges are 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 (eg, chlorine ions, bromine ions, iodine ions, etc.), p-toluenesulfonic acid. Ions, perchlorate ions, boron tetrafluoride ions, sulfate ions, methyl sulfate ions, ethyl sulfate ions, methanesulfonate ions, trifluoromethanesulfonate ions, 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 mol per mol 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. In addition, 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 the organic silver salt in the photosensitive layer, the ratio of the binder to the organic silver salt is preferably in the range of 15: 1 to 1: 2, particularly 8: 1 to 1: 1. That is, it is preferable amount of the binder in the photosensitive layer is a 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 the present invention, it is preferable that the thermal transition temperature after development at a temperature of 100 ° C. or higher is 46 ° C. or higher and 200 ° C. or lower. 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 the endothermic peak when the heat-developed photosensitive layer is isolated and measured. In general, 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 Brand Wrap et al., “Polymer Handbook”, pages III-139 to III-179 (1966, Wiley and Sun, Inc.). Tg in the case of a polymer resin is obtained by the following formula.

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 can be used as a binder contained in a photosensitive layer containing an organic silver salt, photosensitive silver halide grains, a reducing agent, etc. on the support. . 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. These polymer compounds are not particularly limited, and may be homopolymers or copolymers as long as the derived polymer has a glass transition temperature (Tg) in the range of 70 to 105 ° C.

  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 , Dimethyl Minophenoxyethyl, 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 include ethyl, 2-diphenylphosphorylethyl, ω-methoxypolyethylene glycol (addition mol 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, methacrylamides: 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- Ten, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene, etc .; styrenes: for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, tert-butylstyrene , Chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, 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 N-substituted maleimides: As N-substituent, methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl , Benzyl, n-dodecyl, phenyl, 2-methylphenyl, 2,6-diethylphenyl, 2-chlorophenyl, etc .; others include butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate , Diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, glycidyl acrylate, glycidyl methacrylate, N-vinyl oxazolidone, N -Vinylpyrrolidone, acrylonitrile, methacrylonitrile, methylenemalonnitrile, vinylidene chloride and the like can be mentioned.

  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, and 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.

  The unsubstituted aryl group preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group. 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 (e.g., methyl sulfonyl group). 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 indicating the mass of each repeating unit in mol (mol)%, a is 40 to 86 mol%, b is 0 to 30 mol%, c is in the range of 0 to 60 mol%, and a + b + c = The number is 100 mol%, and particularly preferably, a is in the range of 50 to 86 mol%, b is 5 to 25 mol%, and c is in the range of 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 of the polyurethane shown here, if _{necessary, -COOM, -SO 3 M, -OSO} 3 M, -P = O (OM) 2, -O-P = O (OM) 2, (M is hydrogen represents an atom or an alkali metal salt,), - N (R54) 2, -N + (R 54) 3 (R 54 represents a hydrocarbon group, the plurality of R ₅₄ 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 represented by the above general formula (V) according to the present invention is synthesized by a general synthesis method described in “vinyl acetate resin” edited by Ichiro Sakurada (Polymer Chemistry Publishing Society, 1962). Can do.

  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 weight of the total binder. These polymers are not particularly limited as long as the polymers according to the present invention are soluble. More preferably, polyvinyl acetate, a polyacrylic resin, a urethane resin, etc. are mentioned.

  In the present invention, it is known that the use of a crosslinking agent with respect to 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 ethylene described in JP-A-50-96216. Although imine, vinyl sulfone, sulfonic acid ester, acryloyl, carbodiimide, and silane compound crosslinking agents can be used, the following isocyanate compounds, silane compounds, epoxy compounds, or acid anhydrides are preferred.

  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, alkenyl group, aryl group or alkylaryl group, a (v + 1) -valent linking group, and X ₂ 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 is an isocyanate having at least two isocyanate groups and adducts thereof (adducts), more specifically, aliphatic diisocyanates, 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 polyisocyanates with these isocyanates Examples include adducts with alcohols.

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

  The adduct body of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion and prevent peeling of layers, image shift and generation of bubbles. 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 layer on the side 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, a good result 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, but by introducing a diffusion-resistant group, the intramolecular movement distance at room temperature can be suppressed and 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.

  Epoxy compounds can be added to any layer on the photosensitive layer side of the support, such as photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc., and added to one or more of these layers can do. 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 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, and one of these layers or 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. The reducible silver source (organic silver salt), the photosensitive silver halide particles, the reducing agent, and the color tone of silver as required. It is preferable that the toning agent to be adjusted is usually contained in a dispersed state in an (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. Has been. A particularly preferable colorant is a combination of phthalazinone or phthalazine with phthalic acids or phthalic anhydrides.

  As for the color tone of an output image for conventional medical diagnosis, it is said that a cold tone image tone is easier for an X-ray photograph reader to obtain a more accurate diagnosis observation result of a recorded image. Here, the cool tone is a pure black tone or a bluish black tone with a black image, and the warm tone tone is a black tone with a brown tone. .

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 range of hab 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 in order to prevent damage, and it is preferable to contain 0.1 to 30% by mass ratio 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 British Patent No. 1,173,181. Alkaline earth metals or carbonates such as cadmium and zinc described in the book can be used as the matting agent. Examples of organic substances include starch described in US Pat. No. 2,322,037 and the like, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and the like. No. 44-3643, etc., polyvinyl alcohol described in Swiss Patent No. 330,158, etc., polymethacrylate described in US Pat. No. 3,079,257, etc., polyacrylonitrile described in US Pat. An organic matting agent such as polycarbonate described in Japanese Patent No. 3,022,169 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 the undercoat layer, the backing layer, the 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, and a back coat layer is provided on the opposite side of the support to prevent sticking between photosensitive materials or in a photosensitive material roll. Preferably it is provided. Binders used in these protective layers and backcoat layers have a glass transition point higher than that of a heat-developable layer, and polymers such as cellulose acetate and cellulose acetate butyrate are less likely to be scratched or deformed. Chosen from. For the purpose of expanding the latitude, it is one of preferred embodiments of the present invention that two or more photosensitive layers are provided on one side of the support or one or more layers are provided 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 photosensitive 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, a thiopyridium dye). A squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. preferable.

  The compound having a squarylium nucleus is a compound having 1-cyclobutene-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.

  As the dye, the compounds described in JP-A-8-201959 are also preferable.

  The photothermographic material of the present invention is preferably formed by preparing a coating solution in which the above-mentioned constituent layers are dissolved or dispersed in a solvent, applying a plurality of these coating solutions simultaneously, and then performing a heat treatment. . Here, “multiple simultaneous multi-layer coating” means that a coating solution for each constituent layer (for example, photosensitive layer, protective layer) is prepared, and each layer is repeatedly coated and dried when it is coated on a support. Rather, it means that each constituent layer can be formed in such a state that a multilayer coating and drying process can be performed simultaneously. That is, the upper layer is provided before the remaining amount of the total solvent in the lower layer becomes 70% by mass or less.

  There are no particular limitations 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 is used. be able to. 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 amount of coated silver is preferably selected in accordance with the purpose of the photothermographic material. However, for the purpose of medical images, it is 0.1 g / m ² or more and 2.5 g / m ^2. The following is preferred. Furthermore, 0.5 g / m ² or more and 1.5 g / m ² or less are preferable. Among the applied silver amount, those derived from silver halide preferably occupy 2 to 18%, more preferably 3 to 15%, based on the total silver amount.

In the present invention, the coating density of silver halide grains of 0.01 μm or more (equivalent particle diameter equivalent to sphere) is preferably 1 × 10 ¹⁴ particles / m ² or more and 1 × 10 ¹⁸ particles / m ² or less. Furthermore, 1 × 10 ¹⁵ pieces / m ² or more and 1 × 10 ¹⁷ pieces / m ² or less are preferable.

Further, the coating density of the organic silver salt according to the present invention is 10 ⁻¹⁷ g or more, 10 ⁻¹⁵ g or less, more preferably 10 ⁻¹⁶ g per silver halide grain of 0.01 μm or more (equivalent particle diameter equivalent to sphere). g to 10 ⁻¹⁴ g is preferred.

  In the case of coating under the conditions within the above range, preferable results are obtained from the viewpoint of the optical maximum density of the silver image per fixed coating silver amount, that is, the silver coating amount (covering power) and the color tone of the silver image. Is 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, and when the heating temperature is 200 ° C. or higher, the binder melts, and not only the image itself but also the transportability and the developing machine are adversely affected, such as transfer to a roller. Effect. By heating, a silver image is generated by an oxidation-reduction reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside.

  The apparatus, apparatus, and means for heating may be performed by a heating means typical as a heat generator using a hot plate, iron, hot roller, carbon, white titanium, or the like. More preferably, in the photothermographic material provided with the protective layer of the present invention, the surface on the side having the protective layer is brought into contact with the heating means and the heat treatment is performed. It is preferable from the point of view, and it is preferable that the surface is conveyed while being brought into contact with a heat roller, heated and developed.

  In the exposure of the photothermographic material of the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, when the photosensitive material is sensitive to infrared light, it can be applied to any light source as long as it is in the infrared light range. However, the laser power is high and the photosensitive material can be transparent. In view of the above, an infrared semiconductor laser (780 nm, 820 nm) is more preferably used.

  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 photosensitive 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 degrees or more and 88 degrees or less, more preferably 60 degrees or more and 86 degrees or less, and further Preferably it is 65 degrees or more and 84 degrees or less, Most preferably, it is 70 degrees or more and 82 degrees or less.

  The beam spot diameter on the photosensitive material exposure surface when laser light 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, the exposure in the present invention is preferably performed using a laser scanning exposure machine that emits a scanning laser beam 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, this invention is not limited to these.

Example 1
《Preparation of underdrawn 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, the other surface is similarly subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , and then the undercoat coating solution B described below is 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.

<Preparation of undercoat coating liquid A>
270 g of copolymer latex liquid (solid content 30%) of 30% by mass of n-butyl acrylate, 20% by mass of tert-butyl acrylate, 25% by mass of styrene and 25% by mass of 2-hydroxyethyl acrylate, surfactant (UL-1 ) 0.6 g and methyl cellulose 0.5 g were mixed. Further, 1.3 g of silica particles (Syloid 350, manufactured by Fuji Silysia) was added to 100 g of water, and dispersion treatment was performed for 30 minutes with an ultrasonic disperser (manufactured by ALEX Corporation, Ultrasonic Generator, frequency 25 kHz, 600 W). The solution was added and finally made up to 1000 ml with water to obtain the undercoat coating solution 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. This was then boiled to obtain a coprecipitate. 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.

<Preparation of undercoat coating solution B>
Copolymer latex liquid (solid content 30) of 37.5 g of the colloidal tin oxide dispersion, 20% by mass of n-butyl acrylate, 30% by mass of tert-butyl acrylate, 27% by mass of styrene and 28% by mass of 2-hydroxyethyl acrylate. %) 3.7 g, n-butyl acrylate 40 mass%, styrene 20 mass%, glycidyl methacrylate 40 mass% copolymer latex liquid (solid content 30%) 14.8 g and 0.1 g surfactant UL-1 Were mixed and finished to 1000 ml with water to obtain an undercoat coating solution B.

<< Preparation and application of back surface coating liquid >>
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 active agent (Asahi Glass Co., Surflon KH40) dissolved in 43.2 g of methanol and F-type active agent (Dainippon Ink, Inc.) , Megafag F120K) 2.3 g was added and stirred well until dissolved. Finally, 75 g of silica (WR Grace Co., Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% by mass 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 on the undercoat layer b by an extrusion coater 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 photosensitive 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 (CH3) CH 2 O) 17 (CH 2 CH 2 O) m H
(M + n = 5-7)
Using the mixing stirrer disclosed in each of Japanese Patent Publication Nos. 58-58288 and 58-58289, a 1/4 amount of the solution (B1) and a total amount of the solution (C1) were added to the solution (A1) at a temperature of 30 ° C., pAg8 While controlling at 0.09, nucleation was performed by adding 4 minutes and 45 seconds by the simultaneous mixing method. After 1 minute, the entire amount of solution (F1) was added. During this time, the pAg was appropriately adjusted 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 equivalent to 1/20 mol of this sensitizer was added, and the emulsion was heated at 55 ° C. Chemical sensitization was performed by stirring for 120 minutes. This is designated as photosensitive 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 1.5M sodium hydroxide aqueous solution was added, 6.9 ml of concentrated nitric acid was added, and then cooled to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the fatty acid sodium solution at 55 ° C., 45.3 g of the above photosensitive 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% of the internal volume of 0.5 mm diameter zirconia beads (Torayserum manufactured by Toray) so that the residence time in the mill is 1.5 minutes using a pump. Photosensitive emulsion dispersion A was prepared by supplying to C12EX type (VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<Preparation of stabilizer solution>
1.0 g of Stabilizer 1 and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare a stabilizer solution.

<Preparation of infrared sensitizing dye liquid A>
19.2 mg of infrared sensitizing dye 1, 1.488 g 2-chloro-benzoic acid, 2.7779 g stabilizer 2 and 365 mg 5-methyl-2-mercaptobenzimidazole in 31.3 ml MEK in the dark Infrared sensitizing dye liquid A was prepared.

<Preparation of additive solution a>
Silver ion reducing agent (compound described in Table 1) 6.0 g × 10 ⁻² / 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 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 mass% MEK solution) was added. And stirred for 15 minutes. While further stirring, 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 / Morvey Aliphatic isocyanate (10% MEK solution), 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, 7.5 g CAB171-15) was dissolved in 42.5 g of MEK, and 5 g of calcium carbonate (Speciality Minerals, Super-Pflex200) was added thereto, and 8000 rpm with a dissolver type homogenizer. For 30 minutes to prepare a matting agent dispersion.

<< 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, it dried for 10 minutes using the drying air with a drying temperature of 75 degreeC and dew point temperature of 10 degreeC, and produced each sample.

VSC: (CH ₂ = CHSO ₂ CH ₂ ) ₂ CHOH
[Exposure and development processing]
From the emulsion surface side of the sample prepared as described above, exposure by laser scanning was given by an exposure machine using a semiconductor laser which was converted into a longitudinal multimode with wavelengths of 810 nm and 814 nm by high frequency superposition as an exposure source. 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 evaluation was performed on each image obtained as described above.

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

<Evaluation of image color tone>
The color tone of the obtained image was observed and evaluated based on the following criteria. Practically, it is preferably rank 4 or higher.
Rank: Evaluation criteria for color tone 5: No darkness in cold black tone 4: Not a cool black tone, almost no redness 3: Partially slightly reddish 2: Partially reddish 1 : At first glance, redness is felt.

<Evaluation of image preservation>
For each image obtained by exposure with a semiconductor laser at 810 nm, the image storage stability was evaluated by measuring the image density change rate in the minimum density portion and the maximum density portion according to the following method.

(Evaluation of image storability of minimum density part)
In the same manner as the above sensitivity, fog, and maximum density measurement methods, each of the produced heat-development-treated samples was subjected to a commercially available white fluorescent lamp in an environment of 45 ° C. and 55% RH, and the illuminance on the sample surface was 500 lux. 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, A scale. The closer the value is to 100, the better. Minimum density change rate = D2 / D1 × 100 (%).

(Evaluation of image storage stability at the highest density area)
Each heat-developed sample prepared by the same method as the measurement of the minimum density change rate is allowed to stand for 3 days in an environment of 25 ° C. and 45 ° C., and then the change in the maximum density is measured. The rate of change in image density was measured and 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 (%).

  Furthermore, according to the following evaluation criteria, the color tone change of the image was visually evaluated and evaluated in five stages.

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 considerable part 1: Increase in color change is remarkable

  From Table 1, the photothermographic material of the present invention has not only good color tone but also good sensitivity, maximum density and fog, and oscillation when exposed using a laser scanning exposure machine. The sensitivity and maximum density of the output image are extremely stable with respect to wavelength fluctuations.

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 stretched 3.3 times in the longitudinal direction using rolls with different peripheral speeds, and then stretched 4.5 times in the 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 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

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

<Preparation of undercoat layer coating solution>
Formula (for photosensitive layer side undercoat layer)
Pesresin A-515GB (30% by mass solution, manufactured by Takamatsu Yushi Co., Ltd.) 234 g
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5, 10% by mass solution) 21.5 g
MP-1000 (polymer fine particles, average particle size 0.4 μm, manufactured by Soken Chemical Co., Ltd.)
0.91g
744 ml of distilled water
Formula (for back layer 1st layer)
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% by mass aqueous solution) 20 g
Sodium laurylbenzenesulfonate (1% by weight aqueous solution) 10 ml
854 ml of distilled water
Formula (for back layer 2nd layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion)
84g
Gelatin (10 mass% aqueous solution) 89.2g
Metroz TC-5 (2% by weight aqueous solution, manufactured by Shin-Etsu Chemical Co., Ltd.) 8.6 g
MP-1000 (polymer fine particles, manufactured by Soken Chemical Co., Ltd.) 0.01 g
Sodium dodecylbenzenesulfonate (1% by weight aqueous solution) 10 ml
NaOH (1% by mass) 6 ml
Proxel (ICI) 1ml
805 ml of distilled water
<< Preparation of undercoat support >>
After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating liquid formulation (for the photosensitive layer side undercoat layer) is applied to one side (photosensitive layer surface) with a wire bar. Apply the wet coating amount to 6.6 ml / m ² (per one side), dry at 180 ° C. for 5 minutes, and then apply the undercoat coating liquid formulation (for back side first layer) to this back side (back side) Is applied with a wire bar so that the wet coating amount is 5.7 ml / m ² , dried at 180 ° C. for 5 minutes, and the above-mentioned undercoat coating liquid formulation (for back surface side second layer) is applied to the back surface (back surface). ) Was applied with a wire bar so that the wet coating amount was 7.7 ml / m ² and dried at 180 ° C. for 6 minutes to prepare an undercoat support.

<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 demole N manufactured by Kao Corporation were mixed with 220 ml of distilled water, and the mixture was mixed with a sand mill (1/4 Gallon sand grinder mill, Imex Corporation). 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 used with a sand mill (1/4 Gallon sand grinder mill, manufactured by Imex Corp.). The beads were dispersed to obtain a dye solid fine particle dispersion having an average particle size of 0.2 μm.

<< Preparation of antihalation layer coating liquid >>
Gelatin 17 g, polyacrylamide 9.6 g, solid fine particle dispersion (a) 70 g of the above-mentioned precursor precursor, 56 g of the above 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, water 844 ml mixed to prevent halation A layer coating solution was prepared.

<< Preparation of back surface protective layer coating liquid >>
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, Aerosol OT (American Cyanamid Co.) 0.6 g, and 1.8g of liquid paraffin emulsion as liquid paraffin, water was mixed 950 ml, was the back surface protective layer coating solution.

(Preparation of silver halide emulsion)
To a solution of 1421 ml of distilled water, 3.1 ml of a 1% by mass potassium bromide solution was added, and a solution containing 3.5 ml of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 30 ° C., distilled water was added to 22.22 g of silver nitrate, and the solution A diluted to 95.4 ml, 15.3 g of potassium bromide, and 0.8 g of potassium iodide were added in a volume of 97. Solution B diluted to 4 ml was added at a constant flow rate over 45 seconds.

Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and further 10.8 ml of a 10% by mass aqueous solution of benzimidazole was added. Further, a solution C in which distilled water was added to 51.86 g of silver nitrate and diluted to 317.5 ml, a solution D in which 44.2 g of potassium bromide and 2.2 g of potassium iodide were diluted with distilled water to a volume of 400 ml were added to solution C. Was added at a constant flow rate over 20 minutes, and solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of the solution C and the solution D so as to be 1 × 10 ⁻⁴ mol per mol of silver. Further, 5 seconds after the completion of the addition of the solution C, a total amount of 3 × 10 ⁻⁴ mol of iron (II) hexacyanide aqueous solution per 1 mol of silver was added. 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.

While maintaining the silver halide dispersion at 38 ° C. with stirring, 5 ml of a methanol solution of 0.34% by mass of 1,2-benzisothiazolin-3-one was added, and after 40 minutes, spectral sensitizing dye A and the spectral solution were added. A methanol solution having a molar ratio of sensitizing dye B of 1: 1 was added in a total 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. . After 20 minutes of temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol with respect to 1 mol of silver, and further 5 minutes later, tellurium sensitizer C was added to the methanol solution in an amount of 2.9 × with respect to 1 mol of silver. 10 ^-4 mol was added and the mixture was aged for 91 minutes. 1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and after 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4. 8 × 10 ⁻³ mol and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole were added in a methanol solution to a silver halide by adding 5.4 × 10 ⁻³ mol to 1 mol of silver. Emulsion 1 was prepared, and the grains in the prepared silver halide emulsion were silver iodobromide grains 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, etc. was determined from the average of 1000 particles using an electron microscope, and the {100} face ratio of these particles was determined to be 80% using the Kubelka-Munk method.

<Preparation of mixed emulsion A for coating solution>
70% by weight of silver halide emulsion 1, 15% by weight of silver halide emulsion 2 and 15% by weight of silver halide emulsion 3 were dissolved, and 7 × per mol of silver in a 1% by weight aqueous solution of benzothiazolium iodide. 10 ⁻³ mol 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 silver nitrate aqueous solution were 93 minutes and 15 seconds at a constant flow rate, respectively. And added over 90 minutes. At this time, only the aqueous silver nitrate solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. It was to so. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The piping of the sodium behenate solution addition system was prepared by keeping warm water by circulating hot water outside the double pipe so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. In addition, the piping of the silver nitrate aqueous solution addition system was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically 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 filtered off by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying. When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter. It was a scaly crystal having a coefficient of variation of 0.52 μm and a sphere equivalent diameter of 15%. The coefficients a, b, and c are a, b, and c from the shortest side of the rectangular parallelepiped when the shape of the organic silver salt particle is approximated to a rectangular parallelepiped.

19.3 kg of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA-217) 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 then slurried with a dissolver blade, and further a pipeline mixer ( Pre-dispersed by Mizuho Kogyo, PM-10 type). Next, the pre-dispersed stock solution was adjusted to a pressure of 1.235 × 10 ⁸ Pa in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber). , Three times 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 mass% aqueous solution of 6.0 g × 10 ⁻² / 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% by mass to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.42 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 general formula (1)>
75 g of water was added to 150 g of the compound represented by the general formula (1) (compound and amount described in Table 2) and modified polyvinyl alcohol (Kuraray Co., Ltd., 10% by weight aqueous solution of 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 a development accelerator-1 and 150 g of a 10% by weight 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% by mass 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 an organic polyhalogen compound-1 (2-tribromomethanesulfonyl naphthalene), 10 kg of a 20 wt% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), and a 20 wt% aqueous solution of sodium triisopropyl naphthalenesulfonate 0 4 kg and 16 kg of water were 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% by mass to obtain an organic polyhalogen compound-1 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.36 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 wt% aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), 0.4 kg of 20 wt% aqueous solution of sodium triisopropylnaphthalenesulfonate And 14 kg of water were added and mixed well to form a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal bead mill filled with zirconia beads having an average diameter of 0.5 mm (manufactured by Imex Co., Ltd., UVM-2), and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass 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 (manufactured by Kuraray Co., Ltd., MP203) was dissolved in 174.57 kg of water, and then 3.15 kg of a 20 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 (6-isopropylphthalazine) Was added to prepare a 5% by mass 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% by mass aqueous solution.

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

<Preparation of SBR latex solution>
An SBR latex having a Tg of 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 to 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: Latex of -St (70.5) -Bu (26.5) -AA (3)-) Tg23 ° C.

  Average particle size 0.1 μm, concentration 43% by mass, equilibrium moisture content 0.6% by mass at 25 ° C. and relative humidity 60%, ion conductivity 4.2 mS / cm (measurement of ion conductivity is made by Toa Denpa Kogyo Co., Ltd.) Conductivity meter CM-30S was used and latex stock solution (43% by mass 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 the well-mixed 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, and 10,000 at shear rates of 0.1, 1, 10, 100, and 1000 [1 / second], respectively. 70, 40, and 20 [mPa · s].

<Preparation of emulsion surface intermediate layer coating solution>
772 g of 10% by weight aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 5.3 g of 20% by weight dispersion of pigment, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization) Mass ratio 64/9/20/5/2) 2 ml of aerosol OT (manufactured by American Cyanamid Co., Ltd.) 226 g of 27.5 mass% latex 2 ml, 20 mass% aqueous solution of diammonium phthalate 10.5 ml, water was added to a total amount of 880 g, and the pH was adjusted to 7.5 with NaOH 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, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5/2) 27.5% by weight latex 80 g, 23 ml of a 10% by weight methanol solution of phthalic acid, 23 ml of a 10% by weight aqueous solution of 4-methylphthalic acid, 28 ml of sulfuric acid having a concentration of 0.5 mol / L, and a 5% by weight aqueous solution of Aerosol OT (American Cyanamid Co., Ltd.) Add 5 ml, 0.5 g phenoxyethanol, 0.1 g benzoisothiazolinone, add water to make a total amount of 750 g, and use 26 ml of 4% by weight chromium alum mixed with a static mixer just before coating. The solution was fed to the coating die so as to be 18.6 ml / m ² . The viscosity of the coating solution was 17 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) B-type viscometer.

[Preparation of photothermographic material]
On the back surface side of the undercoat support, the antihalation layer coating solution is applied so that the solid coating amount of the solid fine particle dye is 0.04 g / m ^2, and the back surface protective layer coating solution is prepared with a gelatin coating amount of 1. A simultaneous multilayer coating was applied so as to be 7 g / m ² , followed by drying to produce a back layer. A photothermographic material sample was prepared on the surface opposite to the back surface by simultaneous multi-layer coating using the slide bead coating method in the order of the emulsion layer, intermediate layer, protective layer first layer, and protective layer second layer from the undercoat surface. . 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 g × 10 ⁻³
Compounds represented by general formula (1) Kinds and amounts 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 was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set to be 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 produced had a matte degree of 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.

<< Exposure and development process >>
(Evaluation of photographic performance)
The photosensitive material was exposed with a Fuji Medical Dry Laser Imager FM-DPL L (mounted with a 660 nm semiconductor laser having a maximum output of 60 mW (IIIB)). After the exposure, the FM-DPL thermal development unit is remodeled and four panel heaters set for thermal development (112 ° C-119 ° C-121 ° C-121 ° C) for a total of 24 seconds (standard development time is 24 seconds) ) Developed.

<Evaluation of photographic performance>
Each item was evaluated in the same manner as in Example 1. The results are shown in Table 2.

  The results obtained for the above evaluation are shown in Table 2. 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)

A photothermographic material having a photosensitive layer containing a non-photosensitive organic silver salt, silver halide, silver ion reducing agent and binder on a support, containing a compound represented by the following general formula (1): A heat-developable photosensitive material.

In (formula _{(1), R 1, R} 2, R 3 and R ₄ are each independently a hydrogen atom, .X representing a substituent group or a halogen atom O, .R ₅ representing S or N-R ₅ is Represents a hydrogen atom or a substituent, R ₆ and R ₇ represent a hydrogen atom, a substituent or a halogen atom, but R ₆ and R ₇ are not a phenyl group at the same time.) 2. The photothermographic material according to claim 1, wherein in the general formula (1), one of R ₆ and R ₇ is a phenyl group. 3. The photothermographic material according to claim 2, wherein, in the general formula (1), the other of R ₆ and R ₇ which is not a phenyl group is an alkyl group. The photothermographic material according to claim 1, wherein, in the general formula (1), R ₁ and R ₂ are represented by 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 represent 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 of the compound represented by the general formula (1) to the silver ion reducing agent (mol number of the compound represented by general formula (1) / mol number of the silver ion reducing agent) is 0.001 to 0.00. The photothermographic material according to claim 1, wherein the photothermographic material is 15.