JP2005274812A - Heat developable photosensitive material and image recording method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having superior storage stability, high maximum density, little fogging, proper silver tone and high latitude with respect to variations in the environmental humidity condition, and to provide an image recording method for the same. <P>SOLUTION: The heat developable photosensitive material contains on a support an organic silver salt, a photosensitive silver halide and reducing agents for silver ions, wherein at least one of the reducing agents for silver ions is represented by Formula (1). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photothermographic material and an image recording method thereof. More specifically, the present invention relates to a photothermographic material having excellent storage stability, high maximum density, low fog, good silver tone, and high tolerance for fluctuations in environmental humidity conditions, and an image recording method thereof.

  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, and this technique is well known (for example, Patent Documents 1 and 2). See.) Since these photosensitive materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

  The photothermographic material has a much larger number of kinds and added amounts of built-in chemical substances than the conventional photosensitive material processed by liquid processing, and accordingly, the film thickness of the photosensitive layer and the non-photosensitive layer is increased. It tends to increase. As a result, the coating process or the drying process at the time of manufacturing the 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 is effective in reducing the film thickness in a photosensitive material. However, mere reduction of the amount of silver is not preferable because it causes a decrease in image density. In order to reduce the silver amount and not reduce the image density, it is effective to increase the number of development points per unit area and increase the covering power. Conventionally, a technology for obtaining high image density with a low silver amount has been established by using “infectious development” with a nucleating agent in a photosensitive material for printing, and a method for obtaining a high image density has been described (for example, Patent Documents 3 and 4). However, the light-sensitive materials described in these publications have poor storage stability, high fog, and the color tone of the formed image silver is yellowish. In addition, the maximum density is low, and particularly when the environmental humidity is lowered, the sensitivity and density are extremely lowered, which is a big problem particularly in printing applications. A silver ion reducing agent having a specific cyclic substituent has been disclosed (see, for example, Patent Documents 5 and 6), and generally good improvement has been achieved with respect to the above problems. Improvement in tolerance, more specifically, sensitivity under low humidity, and sufficient improvement with respect to density reduction have not been achieved.
US Pat. No. 3,152,904 US Pat. No. 3,487,075 D. Mrygan; Dry Silver Photographic Materials: (Handbook of Imaging Materials, Marcel Dekker, Inc., p. 48, 1991). Japanese National Patent Publication No. 10-512061 Japanese National Patent Publication No. 11-511571 European Patent Publication No. 1,357,424 JP 2003-302723 A

  An object of the present invention is to solve the above-mentioned problems, a photothermographic material having excellent storage stability, high maximum density, low fog, good silver tone, and high tolerance for fluctuations in environmental humidity conditions. And an image recording method thereof.

  The above object of the present invention can be achieved by the following configuration.

(Claim 1)
In a photothermographic material containing an organic silver salt, a photosensitive silver halide, and a silver ion reducing agent on a support, at least one of the silver ion reducing agent is represented by the following general formula (1): A heat-developable photosensitive material.

[Wherein, R ₀ ′ and R ₀ ″ represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, Q ₀ represents a substitutable group on the benzene ring, and n and m are 0-2. A plurality of Q _{0 s} may be the same or different, R _x represents a hydrogen atom or an alkyl group, R ₁ is a hydrogen atom, or R ₄ is necessary for bonding to each other to form a ring. R ₂ represents a hydrogen atom, a halogen atom, a substituent having 0 or 1 carbon atoms and containing at least one atom selected from an oxygen atom, a sulfur atom or a nitrogen atom, or a substituent having 2 or more carbon atoms R ₃ represents a hydrogen atom, a halogen atom, or a substituent, and R ₄ represents a hydrogen atom, a halogen atom, a substituent, or an atomic group necessary for bonding to R ₁ to form a ring. R ₅ represents a hydrogen atom or a methyl group.]
(Claim 2)
2. The photothermographic material according to claim 1, further comprising a nucleating agent.

(Claim 3)
An image recording method comprising exposing the photothermographic material according to claim 1 or 2 using a laser scanning exposure machine having an oscillation wavelength of 600 nm to 1100 nm.

  According to the present invention, it is possible to provide a photothermographic material having excellent storage stability, high maximum density, low fog, good silver color tone, and high tolerance for fluctuations in environmental humidity conditions, and an image recording method thereof. did it.

  The present invention will be described in more detail. In the present invention, a compound having a specific 6-membered ring substituent in which at least one of the silver ion reducing agents is a bisphenol derivative is used alone or in combination with other reducing agents having different chemical structures. In the photothermographic material according to the present invention, it is possible to unexpectedly suppress performance deterioration due to fogging and the like, deterioration in color tone of the silver image after heat development, deterioration in storage stability, and the like. In particular, in combination with a nucleating agent, a surprising effect can be obtained in both medical and printing applications, such as a photosensitive material having a high maximum density and excellent tolerance to fluctuations in environmental humidity conditions.

  The reducing agent used in the present invention is preferably a bisphenol derivative represented by the general formula (1).

  Next, the compound represented by the general formula (1) according to the present invention will be described in detail.

R ₀ ′ and R ₀ ″ represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and the alkyl group is specifically preferably an alkyl group having 1 to 10 carbon atoms. Methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, cyclohexyl group, cycloheptyl group, 1- Methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-cycloalkenyl group, 2-cycloalkenyl group Ethynyl group, 1-propynyl group, etc. More preferably, methyl group, ethyl group, isopropyl group, t-butyl group, cyclohexyl 1-methylcyclohexyl group, etc., preferably a methyl group, a t-butyl group, and a 1-methylcyclohexyl group, and most preferably a methyl group.Specific examples of the aryl group include a phenyl group, a naphthyl group, Specific examples of the heterocyclic group include a pyridine group, a quinoline group, an isoquinoline group, an imidazole group, a pyrazole group, a triazole group, an oxazole group, a thiazole group, an oxadiazole group, a thiadiazole group, and a tetrazole group. And non-aromatic heterocyclic groups such as a piperidino group, morpholino group, tetrahydrofuryl group, tetrahydrothienyl group, tetrahydropyranyl group, etc. These groups may further have a substituent. Well, examples of the substituent include the above-mentioned substituents on the ring. Kill. Multiple R ₀ ', R ₀ "may be the same or different, but all most preferably is the case of methyl group.

Q ₀ 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 group (phenyl group etc.), heterocyclic group (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 ( Elementary 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), 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) Ruaminosulfonyl 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), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethyl group) Aminocarbonyl 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. These groups may be further substituted with these groups. n and m represent integers of 0 to 2, most preferably n and m are both 0.

R _x represents a hydrogen atom or an alkyl group. Specifically, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, cyclohexyl group, cycloheptyl. Group, 1-methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-cycloalkenyl group, 2 -A cycloalkenyl group, an ethynyl group, a 1-propynyl group, etc. are mentioned. More preferably, a methyl group, an ethyl group, an isopropyl group, etc. are mentioned. Preferably R _x is a hydrogen atom.

R ₁ represents a hydrogen atom or an atomic group necessary for forming a ring by bonding to R _4, and the ring includes a carbon atom to which R ₁ , R ₄ , R ₅ , and R _x are bonded. Represents a 5-membered ring, specifically a cyclopentane ring, a tetrahydrofuran ring, or a tetrahydrothiophene ring. R ₁ is preferably a hydrogen atom or a case where it is combined with R ₄ to form a cyclopentane ring, more preferably a hydrogen atom.

R ₂ represents a hydrogen atom, a halogen atom, a carbon number of 0 or 1, and a substituent containing an oxygen atom, a sulfur atom or a nitrogen atom, or a substituent having 2 or more carbon atoms, and the carbon number is 0 or 1 Specific examples of the substituent containing an oxygen atom, sulfur atom or nitrogen atom include acetyl group, aminocarbonyl group, aminosulfonyl group, sulfo group, amino group, methylamino group, aminomethyl group, hydroxymethyl group, mercaptomethyl. Group, methoxyl group, methylthio group, methanesulfonyl group, methanesulfonylamino and the like. Specific examples of the substituent having 2 or more carbon atoms include alkyl groups having 2 to 25 carbon atoms (ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, etc.), cycloalkyl Group (cyclohexyl group, cyclopentyl group, etc.), alkynyl group (propargyl group, etc.), glycidyl group, acrylate group, methacrylate group, aryl group (phenyl group, etc.), heterocyclic group (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.), alkoxy group (ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group) Hexyloxy group, cycl (Hexyloxy group, etc.), aryloxy group (phenoxy group, etc.), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide Groups (ethanesulfonamide group, butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl groups (dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group) Group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylurea) Group, phenylureido group, 2-pyridylureido group, etc.), acyl group (propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (methylaminocarbonyl group, dimethylaminocarbonyl) Group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl Group (ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (ethylamino group, dimethylamino group, butylamino group, Cyclopentylamino group, anilino group, 2-pyridylamino group, etc.). These groups may be further substituted with these groups. R ₂ is preferably a hydrogen atom or an alkyl group having 2 to 10 carbon atoms, and most preferably a hydrogen atom.

R ₃ represents a hydrogen atom, a halogen atom, or a substituent. Examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an iso-pentyl group, 2-ethyl- Hexyl, octyl, decyl, etc.), cycloalkyl (eg, cyclohexyl, cycloheptyl, etc.), alkenyl (eg, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl) Group, 3-pentenyl group, 1-methyl-3-butenyl group, etc.), cycloalkenyl group (eg, 1-cycloalkenyl group, 2-cycloalkenyl group, etc.), alkynyl group (eg, ethynyl group, 1-propynyl group) Etc.), alkoxy groups (eg methoxy group, ethoxy group, propoxy group etc.), alkylcarbonyloxy groups (eg acetyl) Xy group etc.), alkylthio group (eg methylthio group, trifluoromethylthio group etc.), carboxyl group, alkylcarbonylamino group (eg acetylamino group etc.), ureido group (eg methylaminocarbonylamino group etc.), alkyl A sulfonylamino group (for example, methanesulfonylamino group), an alkylsulfonyl group (for example, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), a carbamoyl group (for example, carbamoyl group, N, N-dimethylcarbamoyl group, N-morpholinocarbonyl) Group), sulfamoyl group (sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkylsulfonamide group (for example, meta Sulfonamide group, butanesulfonamide group, etc.), alkylamino group (for example, amino group, N, N-dimethylamino group, N, N-diethylamino group, etc.), sulfo group, phosphono group, sulfite group, sulfino group, Alkylsulfonylaminocarbonyl group (eg, methanesulfonylaminocarbonyl group, ethanesulfonylaminocarbonyl group, etc.), alkylcarbonylaminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.), alkynylaminocarbonyl group (eg, acetamidocarbonyl) Group, methoxyacetamidocarbonyl group, etc.), alkylsulfinylaminocarbonyl group (for example, methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group, etc.) and the like. R ₃ is preferably a hydrogen atom.

R ₄ represents a hydrogen atom, a halogen atom, a substituent, or an atomic group necessary for bonding to R ₁ to form a ring, and the value substituent has the same meaning as the substituent described for R _4. It is. Further, the atomic group necessary for bonding to R ₁ to form a ring is the same as the atomic group listed for R ₁ . R ₄ is preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom.

R ₅ represents a hydrogen atom or a methyl group, preferably a methyl group.

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

  The compound represented by the general formula (1) of the present invention can be easily synthesized by the following method. A preferred synthesis scheme is illustrated below by taking Compound Example R-1 as an example.

  That is, preferably 2 equivalents of phenol and 1 equivalent of aldehyde are dissolved or suspended in the absence of a solvent or in a suitable organic solvent, and a catalytic amount of acid or alkali is added, preferably at a temperature of -20 ° C to 180 ° C. The target R-1 can be obtained at a good yield by reacting for 0.5 to 60 hours. The same applies to other exemplary compounds.

  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. The catalyst amount is preferably 0.001 to 1.5 equivalents relative to the corresponding aldehyde. The reaction temperature is preferably (15 ° C. to 150 ° C.), and the reaction time is preferably 3 to 20 hours.

  Although the reducing agent represented by General formula (1) may be used independently, you may use it in combination of 2 or more types. Moreover, you may use together the reducing agent of this invention, and other reducing agents.

  Examples of the reducing agent that can be used in combination with the reducing agent represented by the general formula (1) include paragraph numbers 0043 to 0045 of JP-A No. 11-65021 and page 7, lines 34 to 18 of European Patent Publication No. EP0803764A1. It is described in the 12th line of the page. In the photothermographic material of the invention, it is particularly preferable to use a bisphenol reducing agent (for example, 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane) in combination. The reducing agent represented by the general formula (1) is preferably contained in an image forming layer containing an organic acid silver salt, but may be contained in an adjacent non-image forming layer. Specific synthesis examples are shown below, but the present invention is not limited thereto.

  After 24.4 g (20 mmol) of 2,4-xylenol was dissolved in 50 ml of toluene, 17.2 g (10 mmol) of p-toluenesulfonic acid monohydrate was added. 12.4 g (10 mmol) of methylcyclohexenecarbaldehyde was added dropwise at room temperature (23 ° C.). After completion of dropping, the mixture was stirred at room temperature for 20 hours. Further, the mixture was heated and stirred at 60 ° C. for 4 hours. Water (85 ml) and ethyl acetate (200 ml) were added, and the organic layer was separated. The separated organic layer was washed sequentially with 85 ml of saturated aqueous sodium hydrogen carbonate solution and 85 ml of saturated brine. Concentration under reduced pressure was performed. The obtained crude crystals were dissolved in 120 ml of acetonitrile with heating, and then stirred at room temperature for 4 hours. The mixture was further stirred for 3 hours under cooling with ice water, and the precipitated crystals were collected by filtration. The crystals collected by filtration were washed with 40 ml of cooled acetonitrile. Blow drying (one day) was performed at 50 ° C. Yield 30.7 g (yield 88%), melting point 122 ° C., structure was identified by NMR and Mass spectrum.

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

  In the present invention, further, U.S. Pat. Nos. 3,589,903, 4,021,249 or British Patent 1,486,148 and JP-A-51-51933, 50-36110, The polyphenol compounds described in JP-A-50-116023, JP-A-52-84727 or JP-B-51-35727, such as 2,2'-dihydroxy-1,1'-binaphthyl, 6,6'-dibromo-2 Bisnaphthols described in US Pat. No. 3,672,904 such as 2,2'-dihydroxy-1,1'-binaphthyl and the like, and further, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol US Patents such as 2,6-dichloro-4-benzenesulfonamidophenol, 4-benzenesulfonamidonaphthol Sulfonamidophenols or sulfonamidonaphthols, such as those described in 3,801,321 Pat also can be used as the silver ion reducing agent.

  The amount of the silver ion reducing agent of the present invention varies depending on the type of organic silver salt, reducing agent, and other additives, but is generally 0.05 mol to 10 mol, preferably 0, per mol of organic silver salt. 1 mol to 3 mol is suitable. 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 organic silver salt according to the present invention is a reducible silver source and is an organic acid containing a reducible silver ion source. Examples of the organic acid used in the present invention include aliphatic carboxylic acid, carbocyclic carboxylic acid, heterocyclic carboxylic acid, heterocyclic compound and the like, but particularly long chain (10-30, preferably 15-25). The aliphatic carboxylic acid having the number of carbon atoms) and the heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used. An organic silver salt complex having a total stability constant with respect to silver ions having a ligand of 4.0 to 10.0 is also useful.

  Examples of such organic acid silver salts are described in Research Disclosure (hereinafter abbreviated as RD) 17029 and 29963. Of these, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate, and silver stearate are particularly preferably used.

  The organic silver salt compound described above can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and a normal mixing method, a back mixing method, a simultaneous mixing method, and the like are preferably used. It is also possible to use a controlled double jet method as described in JP-A-9-127643.

  In the present invention, the organic silver salt preferably has an average particle size of 1 μm or less and is monodispersed. The average particle diameter of the organic silver salt is, for example, when the organic silver salt particles are spherical, rod-shaped, or tabular, the diameter when considering a sphere equivalent to the volume of the organic silver salt particles. Say. The average particle size is preferably 0.01 to 0.8 μm, particularly preferably 0.05 to 0.5 μm. Moreover, monodispersion is synonymous with the case of the below-mentioned silver halide, Preferably monodispersion degree is 1 to 30%. In the present invention, the organic silver salt is more preferably monodisperse particles having an average particle size of 1 μm or less, and an image having a high density can be obtained by setting the content within this range. Further, the organic silver salt preferably has tabular grains of 60% by number or more of the total organic silver. In the present invention, the tabular grains mean those having an average grain diameter / thickness ratio, that is, an aspect ratio (abbreviated as AR) represented by the following formula of 3 or more.

AR = average particle diameter (μm) / thickness (μm)
Such organic silver particles are preferably preliminarily dispersed together with a binder, a surfactant or the like, if necessary, and then dispersed and ground with a media disperser or a high-pressure homogenizer. As the disperser that can be used in the preliminary dispersion, for example, a general stirrer such as an anchor type or a propeller type, a high-speed rotating centrifugal radiation stirrer (dissolver), or a high-speed rotating shear stirrer (homomixer) may be used. it can. Examples of the media disperser include a rolling mill such as a ball mill, a planetary ball mill, and a vibration ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills, and a high-pressure homogenizer. For example, various types such as a type that collides with a wall, a plug, etc., a type that allows liquids to collide with each other at high speed after dividing the liquid, and a type that allows a thin orifice to pass through can be used.

  In the apparatus used when dispersing the organic silver particles used in the present invention, for example, 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 particles. It is preferable to use zirconia, in particular.

  The organic silver particles used in the present invention preferably contain 0.01 to 0.5 mg of Zr per 1 g of silver, particularly preferably 0.01 to 0.3 mg of Zr. When carrying out the above dispersion, optimizing the binder concentration, the preliminary dispersion method, the dispersing machine operating conditions, the number of times of dispersion, etc. is very preferable as a method for obtaining the organic silver salt particles used in the present invention.

  The photosensitive silver halide according to the present invention preferably has a smaller average grain size, and preferably has an average grain size of 0.1 μm or less, more preferably, in order to suppress white turbidity after image formation and to obtain good image quality. 0.01-0.1 micrometer, especially 0.02-0.08 micrometer are preferable. The particle size here refers to the diameter (equivalent circle diameter) of a circle having the same area as each particle image observed with an electron microscope. The silver halide is preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 20% or less.

Monodispersity = (standard deviation of particle size) / (average particle size value) × 100
The shape of the photosensitive silver halide grains is not particularly limited, but the ratio occupied by the Miller index [100] plane is preferably high, and this ratio is 50% or more, further 70% or more, particularly 80% or more. Preferably there is. 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).

  In the present invention, another preferred shape of the photosensitive silver halide is a tabular grain. The term “tabular grain” as used herein refers to those having an aspect ratio (r / h) of 3 or more when the square root of the projected area is the grain size r μm and the thickness in the vertical direction is h μm. Among them, the aspect ratio is preferably 3 to 50. Moreover, it is preferable that the particle size of a tabular grain is 0.1 micrometer or less, Furthermore, 0.01 micrometer-0.08 micrometer are preferable. These tabular grains 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. it can.

  The photosensitive halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. The emulsion used in the present invention is 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 based on the method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al.

  The photosensitive silver halide according to the present invention preferably contains a metal ion 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 metal ions can be introduced into the silver halide in the form of metal complexes or metal complex ions. As these metal complexes or metal complex ions, hexacoordinate metal complexes represented by the following general formula are preferable.

General formula [ML ₆ ] ⁿ
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, for example, halides (fluorides, chlorides, bromides and iodides), cyanides, cyanates, thiocyanates, selenocyanates, tellurocyanates, azides and acos. Each ligand includes nitrosyl, thionitrosyl, and the like, preferably aco, nitrosyl, thionitrosyl, and the like. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

M is preferably rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) and osmium (Os). Specific examples of transition metal complex ions containing these include [RhCl ₆ ] ^-3 [RhCl ₅ (H ₂ O)] ⁻² , [RhBr ₅ (NO)] ⁻² , [RhCl ₅ (NS)] ⁻² , [RhCl ₄ (NO) (CN)] ⁻¹ , [RhCl (NO) ) (CN) ₄ ] ⁻² , [ReCl ₆ ] ⁻³ , [ReBr ₆ ] ⁻³ , [ReCl ₅ (NO)] ⁻² , [Re (NS) Br ₃ ] ⁻² , [Re (NO) ( CN) _5] ^-2, [RuCl _6] ^-3, [RuCl ₄ (H ₂ O) _2] ^-1, [RuCl ₅ (NO)] ^-2, [RuBr ₅ (NS)] ^-2, [RuCl ₅ (NS)] ^-2, [OsCl _6] ^-3, [OsCl ₅ (NO)] ^-2, [Os (NO) (CN) _5] ^-2, [ Os (NO) (CN)] ⁻¹ , [Os (NS) Br ₅ ] ⁻² , [IrCl ₆ ] ⁻³ , [IrCl ₅ (H ₂ O)] ⁻² , [IrBr ₅ (NO)] ⁻² , [IrCl ₅ (NS)] ^{-2 and the} like.

One kind of metal ion, metal complex or metal complex ion described above may be used, or two or more kinds of the same kind of metal and different kinds of metals may be used in combination. The content of these metal ions, metal complexes or metal complex ions, generally is suitably 1 × 10 ^-9 ~1 × 10 ^-2 mol per mol of silver halide, preferably 1 × 10 ^{- 8} to 1 × 10 ⁻⁴ mol.

  These metal-providing compounds are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, chemical sensitization It may be added at any stage before or after, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Add at the stage of formation.

  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 No. 167545, No. 4-76534, No. 6-110146, No. 5-273683, etc., it can also be contained with distribution in the particles. Preferably, a distribution can be provided inside the particles. 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 a silver salt solution and a halide solution are simultaneously mixed. When adding a third aqueous solution, a method of preparing silver halide grains by a three-liquid simultaneous mixing method, 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 another silver halide grain previously doped with a metal ion or complex ion at the time of preparation and dissolving it. 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 required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during physical ripening, or at the end or chemical ripening.

  In the present invention, the photosensitive silver halide grains may or may not be desalted after grain formation. However, when desalting is performed, for example, the noodle method, the flocculation method, etc. are known in the art. Can be washed with water and desalted.

  The silver halide grains used in the present invention are preferably chemically sensitized. As a preferable chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, a tellurium sensitization method and the like well known in the art can be used. Further, noble metal sensitization methods such as gold compounds, platinum, palladium, iridium compounds, and reduction sensitization methods can be used.

  As the compound preferably used in the above-described sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds can be used. For example, compounds described in JP-A-7-128768 are used. be able to. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Compound having Te bond, tellurocarboxylates, Te-organyl tellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having P-Te bond Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used.

  Examples of the compound preferably used for the noble metal sensitization include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, U.S. Pat. No. 2,448,060 and British Patent 618,061. The compounds described in No. etc. can be preferably used.

  As compounds used in the reduction sensitization method, for example, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. are used. Can do. Further, reduction sensitization can be performed by ripening the silver halide emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower. Further, reduction sensitization can be performed by introducing a single addition portion of silver ions during grain formation.

  Next, components of the photothermographic material of the present invention excluding the above-described items will be described.

  The photothermographic material of the present invention is obtained by laminating an image forming layer and a protective layer containing the above-described organic silver salt, photosensitive silver halide, and the reducing agent of the present invention on a support in this order. Further, it is preferable that an intermediate layer is provided between the support and the image forming layer as necessary.

  Further, a photothermographic material in which a backing layer is provided on the surface opposite to the image forming layer to ensure transportability and prevent blocking with the protective layer can be suitably used. Each layer may be a single layer, or may be composed of two or more layers having the same or different composition.

  In the present invention, a binder resin is preferably used to form each of the above layers. As such a binder resin, a conventionally used transparent or translucent binder resin can be selected and used as appropriate. Examples of such a binder resin include polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral. Polyvinyl acetal resins such as ethyl cellulose, hydroxyethyl cellulose, cellulose resins such as cellulose acetate butyrate, styrene resins such as polystyrene, styrene-acrylonitrile copolymers, styrene-acrylonitrile-acrylic rubber copolymers, polyvinyl chloride, chlorine Vinyl chloride-based resins such as modified polypropylene, polyester, polyurethane, polycarbonate, polyarylate, epoxy resin, acrylic resin, and the like. These may be used alone or in combination of two or more. It may be used in combination with fat.

  In addition, the said binder resin can be suitably selected and used for each layer of a protective layer, an intermediate | middle layer, or the backcoat layer provided when needed, unless the objective of this invention is impaired. In addition, you may use an epoxy resin, an acrylic monomer, etc. which can be hardened | cured with an active energy ray as a layer formation binder resin for an intermediate | middle layer and a backcoat layer. In the present invention, the following aqueous binder resins are also preferably used.

  As a preferable resin, a water-soluble polymer or a water-dispersible hydrophobic polymer (latex) can be used. For example, polyvinylidene chloride, vinylidene chloride-acrylic acid copolymer, vinylidene chloride-itaconic acid copolymer, sodium polyacrylate, polyethylene oxide, acrylic acid amide-acrylic acid ester copolymer, styrene-maleic anhydride copolymer Examples thereof include acrylonitrile-butadiene copolymer, vinyl chloride-acetic acid part nyl copolymer, and styrene-butadiene-acrylic acid copolymer. These constitute an aqueous coating solution, but form a uniform resin film at the stage of drying after coating and forming a coating film. When these are used, an organic silver salt, silver halide, reducing agent, etc. as an aqueous dispersion, mixed with these latexes to form a uniform dispersion, and then applied to form a heat-developable image forming layer Can be formed. By drying, the latex coalesces and forms a uniform film. Further, a polymer having a glass transition point of −20 ° C. to 80 ° C. is preferable, and −5 ° C. to 60 ° C. is particularly preferable. This is because if the glass transition point is high, the temperature at which heat development is carried out becomes high, and if it is low, fogging tends to occur, leading to a reduction in sensitivity and softening. The water-dispersed polymer is preferably dispersed in the form of fine particles having an average particle diameter in the range of 1 nm to several μm. The water-dispersed hydrophobic polymer is called a latex, and is preferably a latex that improves water resistance among widely used binders for aqueous coating. The amount of latex used for the purpose of obtaining water resistance as a binder is determined in consideration of applicability, but is preferably as large as possible from the viewpoint of moisture resistance. The ratio of latex to the total binder mass is preferably 50 to 100%, particularly preferably 80 to 100%.

In the present invention, as these binder resins, the amount of solids is 0.25 to 10 times the amount of silver attached, for example, when the amount of silver attached is 2.0 g / m ² , the amount of polymer attached is It is preferable that it is 0.5-20 g / m < ² >. Further, more preferably 0.5 to 7 times the grain-weight, for example, the amount with silver, if 2.0 g / m ^2, a 1.0~14g / m ^2. If the amount of binder resin is less than 0.25 times the amount of silver, the silver color tone may be significantly deteriorated and may not endure use, and if the amount is more than 10 times the amount of silver, it may become soft and endure use. is there.

  Further, the image forming layer according to the present invention includes, in addition to the above-described essential components and binder resin, an antifoggant, a toning agent, a sensitizing dye, and a substance that exhibits supersensitization (supersensitization). Various additives may also be added.

In the present invention, examples of the antifogging agent include compounds disclosed in US Pat. Nos. 3,874,946 and 4,756,999, —C (X ₁ ) (X ₂ ) ( X ₃ ) (wherein X ₁ and X ₂ represent a halogen atom, and X ₃ represents hydrogen or a halogen atom), a heterocyclic compound having one or more substituents, JP-A-9-288328, No. 9-90550, US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981, 631,176, etc. be able to.

  Examples of toning agents added for the purpose of improving the silver tone after development include imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (for example, succinimide, 3-phenyl). -2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione); naphthalimides (eg N-hydroxy-1,8-naphthalimide); cobalt complexes (eg cobalt hexaminetri) Fluoroacetates), mercaptans (eg 3-mercapto-1,2,4-triazole); N- (aminomethyl) aryl dicarboximides (eg N- (dimethylaminomethyl) phthalimide); blocked pyrazoles , Isothiuronium ) Derivatives and certain photobleaching agents (eg, N, N′-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothione) A combination of uronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole); a merocyanine dye (for example, 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolidine) Nylidene))-1-methylethylidene) -2-thio-2,4-oxazolidinedione); phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg 4- (1-naphthyl) phthalazinone, 6-chlorophthala Dinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedio ); A combination of phthalazinone and a sulfinic acid derivative (eg, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); a combination of phthalazine + phthalic acid; a phthalazine (phthalazine adduct) And maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid) A combination with at least one compound selected from anhydride); quinazolinediones, benzoxazines, naltoxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione) Pyrimidines and asymmetric-tria Gins (eg, 2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene) And preferred color toning agents are phthalazone and phthalazine. The toning agent may be added to the protective layer described later as long as it does not impair the object of the present invention.

  As the sensitizing dye, for example, for an argon ion laser light source, JP-A-60-162247, JP-A-2-48635, US Pat. No. 2,161,331, West German Patent 936,071 Simple merocyanines described in JP-A-5-11389, etc., and trinuclear compounds described in JP-A-50-62425, JP-A-54-18726, and JP-A-59-102229 with respect to a helium neon laser light source. Cyanine dyes, merocyanines described in JP-A-7-287338, Japanese Patent Publication Nos. 48-42172, 51-9609, 55-39818, The thiacarbocyanines described in Japanese Utility Model Laid-Open Nos. 62-284343 and 2-105135 are disclosed in Japanese Patent Application Laid-Open No. 59. No. 191032, 60-80841, tricarbocyanines, JP-A-59-192242, JP-A-3-67242, general formulas (IIIa) and (IIIb) described in 4-quinoline nuclei. Dicarbocyanines and the like to be contained are advantageously selected. Further, in the case where the wavelength of the infrared laser light source is 750 nm or more, more preferably 800 nm or more, in order to cope with the laser in such a wavelength range, JP-A-4-18239, JP-A-5-341432, JP-B-6 Nos. -52387, 3-10931, U.S. Pat. No. 5,441,866, and JP-A-7-13295 are preferably used.

  Further, examples of supersensitizers include RD 17643, JP-B Nos. 9-25500, 43-4933, JP-A-59-19032, 59-192242, JP-A-5-341432, and the like. In the present invention, a heteroaromatic mercapto compound represented by the following general formula (M), which is a general formula (Ma) that substantially forms the mercapto compound, can be used. The disulfide compounds represented can be used.

General formula (M)
Ar-SM
General formula (Ma)
Ar-SS-Ar
In the general formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring or condensed heteroaromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. The heteroaromatic ring is preferably benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, Pyridine, purine, quinoline or quinazoline. Moreover, in general formula (Ma), Ar is synonymous with the said general formula (M).

  The heteroaromatic ring includes, for example, a halogen atom (for example, Cl, Br, I), a hydroxy 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 1 or more carbon atoms, preferably 1 to 4 carbon atoms).

  The supersensitizer used in the present invention is preferably used in the range of 0.001 to 1.0 mol per mol of silver in the emulsion layer containing the organic silver salt and silver halide grains, and particularly 1 mol of silver. The range is preferably 0.01 to 0.5 mol per unit.

  The image recording layer according to the present invention may contain a macrocyclic compound containing a hetero atom. A 9-membered or larger macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a heteroatom is preferred, a 12-24 membered ring is more preferred, and a 15-21 membered ring is still more preferred. is there.

  A typical compound is crown ether, which was synthesized by Pederson in 1967 and has been synthesized many times since its unique report. These compounds are C.I. J. et al. Pederson, Journal of American chemical society vol, 86 (2495), 7017-7036 (1967), G.P. W. Gokel, S.M. H, Korzenowski, “Macrocyclic polyethr synthesis”, Springer-Vergal (1982) and the like.

  In addition to the additives described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used for the image forming layer according to the present invention. As these additives and the other additives described above, compounds described in RD Item 17029 (June 1978, p. 9-15) are preferably used.

  In the present invention, the image forming layer may be a single layer or a plurality of layers having the same or different compositions. The film thickness of the image forming layer is usually 10 to 30 μm.

  Next, the support and the protective layer, which are essential as the layer structure of the photothermographic material of the invention, are described in detail.

  Examples of the support used in the photothermographic material of the invention include acrylic ester, methacrylic ester, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene. , Nylon, aromatic polyamide, polyetheretherketone, polysulfone, polyethersulfone, polyimide, polyetherimide, triacetylcellulose, and other resin films, as well as resin films obtained by laminating two or more layers of the above resins. be able to.

  In the image recording method described later, the support according to the present invention is developed with heat after forming a latent image to form an image. Therefore, a support that has been stretched into a film and heat-set is preferable in terms of dimensional stability. In addition, you may add fillers, such as a titanium oxide, a zinc oxide, barium sulfate, a calcium carbonate, in the range which does not inhibit the effect of this invention. In addition, the thickness of a support body is about 10-500 micrometers, Preferably it is 25-250 micrometers.

  As the protective layer used in the photothermographic material of the present invention, the binder resin described in the above image forming layer can be selected and used as necessary.

  As an additive to be added to the protective layer, it is preferable to contain a filler for the purpose of ensuring damage prevention and transportability of the image after heat development, and the content when the filler is added is in the layer forming composition. It is preferable to contain 0.05-30 mass%.

  Furthermore, in order to improve slipperiness and chargeability, the protective layer may contain a lubricant and an antistatic agent. Examples of such lubricants include fatty acids, fatty acid esters, fatty acid amides, and polyoxyethylene. , Polyoxypropylene, (modified) silicone oil, (modified) silicone resin, fluororesin, carbon fluoride, wax and the like, and antistatic agents include cationic surfactants, anionic surfactants Agents, nonionic surfactants, polymer antistatic agents, metal oxides or conductive polymers, etc., "11290 Chemical Products", Chemical Industry Daily, p. 875-876 etc., the compound described in US Patent No. 5,244,773 columns 14-20, etc. can be mentioned. Furthermore, various additives added to the image forming layer may be added to the protective layer as long as the object of the present invention is not hindered. About 20 mass% is preferable, More preferably, it is 0.05-10 mass%.

  In the present invention, the protective layer may be a single layer or may be composed of a plurality of layers having the same or different composition. In addition, the film thickness of a protective layer is 1.0-5.0 micrometers normally.

  In the present invention, in addition to the above-mentioned image forming layer, support and protective layer, an intermediate layer for improving film attachment between the support and the image forming layer is provided, and a back coat layer is provided for the purpose of transportability and antistatic. In the case of installation, the thickness of the intermediate layer is usually 0.05 to 2.0 μm, and the thickness of the backing layer is usually 0.1 to 10 μm.

  The coating solution for the image forming layer, the coating solution for the protective layer, and the coating solution for the intermediate layer and the backing layer that are installed according to the present invention respectively dissolve or disperse the above-described components in a solvent. Can be prepared.

  Solvents that can be used in the above preparation may be those having a solubility parameter value in the range of 6.0 to 15.0 shown in “Solvent Pocket Book” edited by the Society of Synthetic Organic Chemistry. Examples of the solvent that can be used in the coating solution for forming each layer according to the invention include ketones such as acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, hexylene glycol and the like. Examples of ether alcohols include ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. Examples of ethers include ethyl ether, dioxane, isopropyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, isopropyl acetate and the like. Examples of hydrocarbons include n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of the chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene and the like, but are not limited to these as long as the effects of the present invention are not impaired.

These solvents can be used alone or in combination of several kinds. The residual amount of the solvent in the photothermographic material can be adjusted by appropriately setting the temperature conditions of the drying step after coating, and the residual solvent amount is preferably 5 to 1000 mg / m ^{2 in} total. preferably, a 10-300 mg / m ^2.

  When dispersion is necessary when preparing the coating liquid, for example, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a cobol mill, a tron mill, a sand mill, a sand grinder, a Sqgvari attritor, a high-speed impeller disperser, a high-speed stone Conventionally known dispersers such as a mill, a high-speed impact mill, a disper, a high-speed mixer, a homogenizer, an ultrasonic disperser, an open kneader, and a continuous kneader can be selected and used as appropriate.

  To apply the coating solution prepared as described above, for example, extrusion-type extrusion coater, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, Various known coater stations such as transfer roll coaters, kiss coaters, cast coaters, spray coaters and the like can be selected and used as appropriate. Among these coaters, it is preferable to use a roll coater such as an extrusion type extrusion coater or a reverse roll coater in order to eliminate unevenness in the thickness of the formation layer.

  Further, when the protective layer is applied, there is no particular limitation as long as the image forming layer is not damaged, but the solvent used in the protective layer forming coating solution may dissolve the image forming layer. In the above-described coater station, an extrusion-type extrusion coater, a gravure roll coater, a bar coater or the like can be used. Of these, when using a coating method such as a gravure roll coater or bar coater, the rotation direction of the gravure roll or bar may be forward or reverse with respect to the transport direction. A constant speed or a peripheral speed difference may be provided.

  Furthermore, when laminating each constituent layer, coating and drying may be repeated for each layer, but simultaneous multilayer coating may be performed by a wet-on-wet method and dried. In that case, for example, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, transfer roll coater, kiss coater, cast coater, spray coater, etc. and extrusion type extrusion coater. In such a wet-on-wet multi-layer coating, the upper layer is applied while the lower layer is in a wet state. improves.

  Furthermore, in the present invention, it is preferable that the temperature at which the coating film is dried is in the range of 65 to 100 ° C. in order to effectively draw out the object of the present invention after at least applying the coating solution for the image forming layer. When the drying temperature is lower than 65 ° C., the reaction is insufficient, and thus the sensitivity may vary with time. When the drying temperature is higher than 100 ° C., the photothermographic material itself immediately after production may be changed. Since fogging (coloring) may occur, it is not preferable. The drying time cannot be generally defined by the air volume at the time of drying, but it is usually preferable to dry in the range of 2 to 30 minutes.

  The above-mentioned drying temperature may be dried immediately after coating at a drying temperature in the above-mentioned temperature range, or the vicinity of the surface caused by the marangony of the coating liquid generated during drying or the drying air of warm air is initially dried. For the purpose of preventing unevenness (scratch skin) caused by this, the initial drying temperature may be lower than 65 ° C., and then drying may be performed at a drying temperature in the above-described temperature range.

  As described above, the object of the present invention can be achieved by the photothermographic material of the present invention and the preferred production method thereof, but further, a clear image without interference fringes can be obtained by optimizing the image recording method. be able to.

  Next, an image recording method suitable for the photothermographic material of the present invention will be described in detail.

  The image recording method that can be used in the present invention is roughly divided into three modes depending on the angle formed between the exposure surface and the laser beam, the wavelength of the laser, and the number of lasers used, and they may be performed alone, Two or more types may be combined, and by using such an image forming method, a clear image without interference fringes can be obtained.

  In the present invention, as a preferred aspect of the image recording method, an image is formed by scanning exposure using a laser beam in which the angle formed by the exposure surface of the photothermographic material and the laser beam is not substantially perpendicular. Can be mentioned. In this way, by shifting the incident angle from the vertical, even if reflected light at the interlayer interface is generated, the optical path difference reaching the image forming layer becomes large, so that the scattering and attenuation of the laser light in the optical path is reduced. It occurs and interference fringes are less likely to occur. Here, “substantially not perpendicular” means that the angle that is closest to the vertical during laser scanning is preferably 55 ° to 88 °, more preferably 60 ° to 86 °, and still more preferably. It means 65 degrees or more and 84 degrees or less.

  Further, a more preferable aspect of the image recording method of the present invention is to form an image by scanning exposure using a vertical multi-laser having a non-single exposure wavelength. When scanning with such a vertical multi-laser beam having a width in wavelength, the generation of interference fringes is reduced as compared with a scanning laser beam of a vertical single mode. The term “vertical multi” as used herein means that the exposure wavelength is not single, and the normal exposure wavelength distribution is 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.

Furthermore, in the above-described image recording method, lasers used for scanning exposure are generally well-known solid lasers such as ruby laser, YAG laser, and glass laser; He—Ne laser, Ar ion laser, Kr ion laser, Gas laser such as CO ₂ laser, CO laser, He—Cd laser, N 2 laser, excimer laser; semiconductor laser such as InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb laser; chemical laser A dye laser or the like can be selected and used in a timely manner according to the application. Among these, a semiconductor laser having a wavelength of 600 to 1200 nm is preferably used because of the problem of maintenance and the size of the light source.

  In a laser used in a laser imager or laser image setter, the beam spot diameter on the exposed surface of the photothermographic material when scanned with the photothermographic material is generally from 5 to 75 μm as the minor axis diameter. The shaft diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photothermographic material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the photothermographic material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. In addition,% in a text represents the mass% unless there is particular notice.

Example 1
<< Preparation of photothermographic material >>
A backing layer coating solution was prepared by the method described below.

[Preparation of backing layer coating solution]
While stirring 83 g of methyl ethyl ketone, 8.42 g of cellulose acetate butyrate (manufactured by Eastman Chemical Co., CAB381-20) and 0.45 g of polyester resin (manufactured by Toyobo Co., Ltd., Byron 280) were added and dissolved. 1.03 g of infrared dye 1 was added to the dissolved liquid.

  Separately, 4.34 g of methanol and 0.64 g of a fluorosurfactant (Asahi Glass Co., Ltd., Surflon S-381, active ingredient 70%) and a fluorosurfactant (Dainippon Ink Industries, Ltd., MegaFag F120K) ) 0.23 g was dissolved, and the fluorosurfactant solution was added to the above solution containing the infrared dye 1 and sufficiently stirred until the infrared dye 1 was completely dissolved. Next, 7.5 g of silica (manufactured by WR Grace, Psyloid 64 × 6000) dispersed in methyl ethyl ketone with a dissolver type homogenizer at a concentration of 1% was added and stirred to prepare a backing layer coating solution.

[Application of backing layer]
Corona discharge treatment on one side of a biaxially stretched polyethylene terephthalate (hereinafter abbreviated as PET) film having a thickness of 175 μm colored blue with a visual transmission density of 0.170 (measured with a color transmission densitometer 310T manufactured by X-Rite). After applying (8 W / m ² · min), the above-mentioned backing layer coating solution was applied to the corona discharge treated surface by an extrusion coater so that the dry film thickness was 3.5 g / m ² , and then dried and backing. A layer was formed.

  Next, an image forming layer coating solution and a protective layer coating solution were prepared by the methods described below.

(Preparation of image forming layer coating solution)
(Preparation of photosensitive silver halide emulsion)
After dissolving 7.5 g of ossein gelatin having an average molecular weight of 100,000 and 10 mg of potassium bromide in 900 ml of water, adjusting the temperature to 35 ° C. and pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate (98/2) 10 minutes by a controlled double jet method while maintaining pAg 7.7 in an aqueous solution containing equimolar amounts of potassium bromide and potassium iodide and silver nitrate and 1 × 10 ⁻⁴ mole of iridium chloride per mole of silver. Added over time. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added and the pH was adjusted to 5 with NaOH to obtain an average particle size of 0.06 μm and a coefficient of variation of the particle size. Cubic silver iodobromide grains having 12% and a [100] face ratio of 87% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant and desalted, and 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5 to obtain photosensitive silver halide emulsion 1.

(Preparation of fatty acid sodium solution)
In 4720 ml of pure water, 111.4 g of behenic acid, 83.8 g of arachidic acid, and 54.9 g of stearic acid were dissolved at 80 ° C. Next, 540.2 ml of a 1.5 M / L sodium hydroxide aqueous solution was added while stirring at a high speed, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a sodium fatty acid solution.

(Preparation of powdered organic silver salt)
While maintaining the temperature of the fatty acid sodium solution at 55 ° C., the photosensitive silver halide emulsion 1 (containing 0.038 mol of silver) and 450 ml of pure water were added and stirred for 5 minutes. Next, 760.6 ml of 1M silver nitrate solution was added over 2 minutes, stirred for another 20 minutes, and water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration were repeated until the electrical conductivity of the filtrate reached 2 μS / cm, and centrifugal dehydration was carried out, followed by drying with hot air at 37 ° C. until there was no mass loss, and powdered organic silver salt A Got.

(Preparation of photosensitive emulsion dispersion)
Next, 14.57 g of polyvinyl butyral resin (Denka Butyral # 3000-K, manufactured by Denki Kagaku Kogyo Co., Ltd.) was dissolved in 1457 g of methyl ethyl ketone, and 500 g of the powdered organic silver salt A prepared above was stirred with a dissolver type homogenizer. Was added gradually and mixed well. Thereafter, the dispersion was performed at a peripheral speed of 13 m / s and a residence time in the mill of 0.5 minutes in a media disperser (manufactured by Gettzmann) filled with 80% of zirconia beads having a particle diameter of 1 mm (manufactured by Toray Industries, Inc.) A photosensitive emulsion dispersion was prepared.

(Preparation of image forming layer coating solutions 1 to 15)
50 g of the above photosensitive emulsion dispersion and 10.0 g of methyl ethyl ketone were mixed and kept at 25 ° C. with stirring. 0.320 g of a methanol solution (11.2%) of the antifoggant 1 was added and stirred for 1 hour. Further, 0.425 g of a methanol solution of calcium bromide (11.2%) was added and stirred for 20 minutes, and then 0.90 g of dibenzo-18-crown-6 and 0.28 g of acetic acid were added to 10.0 g of methanol. 0.343 g of a solution in which potassium was dissolved was added and stirred for 10 minutes. Next, after adding the following dye solution 1 (4.007 g) and stirring for 60 minutes, the temperature was lowered to 13 ° C. and stirring was continued for 30 minutes.

<Dye solution 1>
Infrared sensitizing dye 1 0.0103 g
0.244 g of 5-methyl-2-mercaptobenzimidazole
2-chloro-benzoic acid 0.568 g
Benzoic acid derivative 1 4.245 g
Methyl ethyl ketone 25.00g
While keeping the solution to which the dye solution was added at 13 ° C., 13.29 g of polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd., Denkabutyral # 3000-K) was added and dissolved sufficiently. 0.152 g of chlorophthalic acid was added, and the mixture was further stirred for 60 minutes.

  In this solution, the following additive solution 1 (13.543 g), additive solution 2 (5.774 g) and additive solution 3 (4.597 g) dissolved in methyl ethyl ketone were respectively shown in Table 1 of the Examples. Image forming layer coating solutions 1 to 15 were prepared by mixing and stirring sequentially.

<Additive solution 1>
Silver ion reducing agent (described in Table 1) 1.5 × 10 ⁻² mol
4-methylphthalic acid 0.401g
Infrared dye 1 0.0262g
Methyl ethyl ketone 20.00g
<Additive solution 2>
Trihalomethyl group-containing compound 1 1.408 g
Methyl ethyl ketone 20.00g
(Additive solution 3)
Phthalazine 1.420g
Methyl ethyl ketone 20.00g

(Preparation of protective layer coating solution)
While stirring 86.5 g of methyl ethyl ketone, 10.05 g of cellulose acetate butyrate (manufactured by Eastman Chemical Co., CAB171-15), 0.100 g of benzotriazole, fluorine-based activator (Asahi Glass Co., Ltd., Surflon KH40) 10 g was added and dissolved.

  Separately, 5.0 g of silica (Fuji Silysia Chemical Co., Ltd., Silicia 320) is added to a solution of 55.0 g of cellulose acetate butyrate (Eastman Chemical Co., CAB171-15) dissolved in methyl ethyl ketone at a solid content of 15%. It was added and dispersed with a media disperser filled with zirconia beads to prepare a silica dispersion. Next, while stirring the resin solution in which the benzotriazole was dissolved, 3.0 g of a silica dispersion was added, followed by ultrasonic dispersion to prepare a protective layer coating solution.

(Application on the image forming layer side)
The surface of the biaxially stretched PET film having a thickness of 175 μm on which the backing layer is formed is subjected to corona discharge treatment (8 W / m ² · min), and the image formation prepared above is formed on the corona discharge treated surface. The layer coating solutions 1 to 15 and the protective layer coating solution were respectively applied in multiple layers using an extrusion coater and then dried with warm air at 75 ° C. for 10 minutes to prepare photothermographic materials 1 to 15. The thickness after drying was adjusted to the image forming layer 21.0 ± 1.5g / m ^2, the protective layer 2.35 ± 0.15g / m ^2.

<< Image recording method and image evaluation >>
In the photothermographic material prepared above, after preparation, a sample (condition A) of the same day and a sample stored for 120 hours in a thermostatic chamber at 50 ° C. and 55% RH under light shielding conditions (condition B). The exposure amount is changed by an exposure machine using an exposure source of a semiconductor laser having a longitudinal multimode wavelength of 800 to 820 nm by high frequency superimposition from the protective layer surface side of each sample. Then, using an automatic developing machine having a heat drum, image formation was carried out by applying heat development at 122 ° C. for 16 seconds so that the protective layer of the photothermographic material and the drum surface were in contact with each other. In the laser scanning exposure, the angle between the exposure surface of the photothermographic material and the exposure laser beam is 75 degrees, the laser spot diameter on the protective layer surface is an ellipse of 100 μm in the main scanning direction and 75 μm in the sub scanning direction, and the laser scanning pitch is the main. The heat drum used in the heat development was 100 μm in the scanning direction and 75 μm in the sub-scanning direction, and a rubber layer was laminated on the surface, and the centerline average surface roughness Ra defined by JIS B 0601 was 2.0 μm, and the surface roughness was A material having a thickness Sm (average interval of unevenness) of 200 μm and a surface rubber hardness of 60 defined by JIS K6253 type A was used.

  Each photothermographic material subjected to exposure and heat development as described above was evaluated according to the following criteria.

(Measurement of sensitivity)
The transmission density of Visual was measured with a densitometer (manufactured by X-Rite, color transmission densitometer 310T), and the reciprocal of the exposure ratio giving a density 1.0 higher than that of the unexposed area was defined as sensitivity. Photosensitive material No. Evaluation was performed with relative values where the sensitivity of storage condition A of 1 and processing condition 1 was 100. In addition, the exposure amount at which the density becomes an unexposed area +1.0 was determined by linear regression after measuring at least three points between the densities at which the density becomes + unexposed area +0.7 to +1.2.

(Measurement of fogging)
The Visual transmission density of the unexposed portion was measured with a densitometer (manufactured by X-Rite, color transmission densitometer 310T), and the average value was evaluated as fogging.

(Maximum concentration measurement)
The transmission density of Visual at the highest density portion was measured at three points with a densitometer (manufactured by X-Rite, color transmission densitometer 310T), and the average value thereof was obtained. The photothermographic material 1, storage condition A, and processing condition 1 Evaluation was made with a relative value where the maximum concentration was 100.

(Silver tone evaluation)
The density part where the transmission density was 1.1 ± 0.05 was visually observed, and the silver tone was evaluated according to the criteria described below. The rank that has no problem in quality assurance is 4 or more.

5: Pure black tone and no yellowing 4: No blackness, almost no yellowing 3: Partially slightly yellowing 2: Slightly yellowing on the entire surface 1: At first glance And yellowness is felt.

  The obtained evaluation results are shown in Table 1.

  As is clear from Table 1, the sample of the present invention has a higher maximum concentration and less fog, and the sensitivity after storage in a high temperature environment, the decrease in the maximum concentration is small, and the fog rises. Therefore, it can be seen that the raw shelf life is good and the silver tone is also excellent.

Example 2
1. Preparation of undercoated PET support B Plasma treatment 1 was performed on both sides of a 125 μm thick PET film that had been biaxially stretched and heat-set under the following conditions, and then the undercoating liquid a-1 was dried on one surface After coating to a film thickness of 0.8 μm, drying is performed to form an undercoat layer A-1, and on the opposite side, an undercoat coating solution b-1 subjected to the following antistatic treatment is applied to a dry film thickness of 0.8 μm. After being coated so as to become an undercoat layer B-1 as a conductive layer. Next, plasma treatment 2 was performed on the surface of each undercoat layer under the following conditions.

<< Plasma treatment conditions >>
Using a batch type atmospheric pressure plasma processing apparatus (EC-I-H-340, manufactured by EC Chemical Co., Ltd.), the high frequency output is 4.5 kW, the frequency is 5 kHz, the processing time is 5 seconds, and the gas conditions are argon, Plasma treatment 1 and plasma treatment 2 were performed at a volume ratio of nitrogen and hydrogen of 90%, 5%, and 5%, respectively.

<Undercoat coating liquid a-1>
Butyl acrylate (30% by mass)
t-Butyl acrylate (20% by mass)
Styrene (25% by mass)
2-Hydroxyethyl acrylate (25% by mass)
270 g of copolymer latex liquid (solid content 30%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Polystyrene fine particles (average particle size 3 μm) 0.05 g
Colloidal silica (average particle size 90μm) 0.1g
Finish to 1 liter with water <Undercoat coating solution b-1>
Tin oxide (average particle size 36nm doped with 0.1% indium)
Amount to be 0.26 g / m ² Butyl acrylate (30% by mass)
Styrene (20% by mass)
Glycidyl acrylate (40% by mass)
270 g of copolymer latex liquid (solid content 30%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water <Heat treatment of support>
In the undercoating drying step of the obtained undercoated support, the support was heated at 140 ° C. and then gradually cooled. In that case, it conveyed with the tension | tensile_strength of 1 * 10 < ⁵ > Pa.

2. Coating on the back layer side The back layer coating solution 1 and the back protective layer coating solution 1 having the following compositions were filtered using a filter having an absolute filtration accuracy of 20 μm before coating, respectively, and then the prepared support was antistatic processed. On the surface of the undercoat layer B-1, a simultaneous multilayer coating was applied at a rate of 40 m / min so that the total wet film thickness was 30 μm, and drying was performed at 60 ° C. for 4 minutes.

<Back layer coating solution B>
Methyl ethyl ketone 22.2 g / m ²
Infrared dye A 22mg / m ²
Stabilizer B-1 100 mg / m ²
Stabilizer B-2 (Yoshitomi Pharmaceutical Tomissorb 77) 50 mg / m ²
Cellulose acetate propylate (Eastman Chemical CAP504-0.2) 0.5 g / m ²
Cellulose acetate propylate (Eastman Chemical CAP482-20) 1.5 g / m ²
<Back protective layer coating solution 1>
Methyl ethyl ketone 22g / m ²
Surfactant; C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₂ C ₉ F ₁₇ 22 mg / m ²
LiO ₃ S (CF ₂ ) ₃ SO ₃ Li 10 mg / m ²
Cellulose acetate propyleneate (Eastman Chemical CAP482-20) 2.5 g / m ²
Matting agent (Fuji Devison Psyroid 74; silica with an average particle size of 7 μm)
12mg / m ²

(Preparation of silver halide emulsion B)
In 900 ml of pure water, 7.5 g of gelatin and 10 mg of potassium bromide were dissolved, adjusted to a temperature of 35 ° C. and a pH of 3.0, and then brominated at a molar ratio of (96/4) with 370 ml of an aqueous solution containing 74 g of silver nitrate. An aqueous solution containing 5 × 10 ⁻⁶ mol / liter of potassium, potassium iodide and iridium chloride was added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, and the variation coefficient of the projected diameter area was 8%. , [100] silver halide grains made of cubic silver iodobromide having a face ratio of 86% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant, desalted, and 0.1 g phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5 to obtain a silver halide emulsion B.

<< Preparation of organic acid dispersion B >>
130.8 g of behenic acid, 67.7 g of arachidic acid, and 43.6 g of stearic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 M / L sodium hydroxide aqueous solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was 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 silver halide emulsion B and 450 ml of pure water were added and stirred for 5 minutes.

  Next, 702.6 ml of 1 M / 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 dryer (manufactured by Seishin Enterprise Co., Ltd.), the powdered aliphatic carboxylic acid silver salt B 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 B)
14.57 g of polyvinyl butyral resin P-9 was dissolved in 1457 g of methyl ethyl ketone, and 500 g of powdered aliphatic carboxylic acid silver salt B was gradually added while stirring with a dissolver DISPERMATCA-40M manufactured by VMA-GETZMANN. A pre-dispersion B was prepared by mixing.

(Preparation of photosensitive emulsion dispersion B)
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. A photosensitive emulsion dispersion B was prepared by supplying to a C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

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

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

(Image forming layer coating solution B composition)
Photosensitive emulsion dispersion B 1.4 g (in silver) / m ²
Antifoggant 1 1.5 × 10 ⁻⁴ mol / m ²
Calcium bromide 1.8 × 10 ⁻⁴ mol / m ²
Stabilizer liquid B 0.3 g / m ²
Infrared sensitizing dye solution B 2.7 g / m ²
Tetrachlorophthalic acid 7.9 × 10 ⁻⁴ mol / m ²
Silver ion reducing agent (shown in Table 2) 4.8 × 10 ⁻³ mol / m ²
Infrared dye B 3 × 10 ⁻⁵ mol / m ²
4-methylphthalic acid 5 × 10 ⁻⁴ mol / m ²
Nucleating agent (PMP) 0.02 mol / mol Ag
2-Tribromomethylsulfonylpyridine 6.0 × 10 ⁻⁴ mol / m ²
o-phthalic acid 4.0 × 10 ⁻⁴ mol / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Protective layer coating solution B composition)
A surface protective layer coating solution was prepared as follows.

Cellulose acetate butyrate 4g / m ²
Phthalazine 3.2 × 10 ⁻³ mol / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Interlayer coating solution B composition)
Polyvinyl butyral 0.5g / m ²
Polymethyl methacrylate 0.04g / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Application on the image forming layer side)
The image forming layer coating solution B, the intermediate layer coating solution B, and the protective layer coating solution B were respectively applied in this order on the side opposite to the back layer surface using an extrusion coater, and then heated with 75 ° C. hot air. Photothermographic materials 21 to 31 were prepared by drying for 10 minutes. Incidentally, it thickness after drying the image-forming layer 21.0 ± 1.5g / m ^2, an intermediate layer 1.50 ± 0.08g / m ^2, and the protective layer 2.35 ± 0.15g / m ² Adjusted as follows.

<Evaluation of photographic performance>
(Exposure processing)
The obtained photothermographic material was subjected to a single channel cylindrical inner surface type laser exposure apparatus equipped with a semiconductor laser having a beam diameter (FWHM ½ of the beam intensity) of 12.56 μm, a laser output of 50 mW, and an output wavelength of 783 nm. Then, exposure was performed at a mirror rotational speed of 60000 rpm and an exposure time of 1.2 × 10 ⁻⁸ seconds. The overlap coefficient at this time was 0.449, and the laser energy density on the surface of the photothermographic material was 75 μJ / cm ² . Thermal development was performed at 121 ° C. for 20 seconds. Density measurement was performed with a Macbeth TD904 densitometer (visible density). The results are shown in Table 2. Sensitivity is expressed as a logarithm of exposure amount giving a density of 1.5. Relative values are shown with 21 as a reference. The higher the value, the higher the sensitivity.

(Evaluation of development processing humidity dependency)
A photothermographic material was prepared at 23 ° C. and 80% humidity for 12 hours and at 23 ° C. and 20% humidity for 12 hours, and was subjected to heat development processing by exposure to a line width of 50 μm in the same environment.
The dependency of development processing humidity was evaluated by measuring the difference in line width after each processing. Further, the difference in Dmin (fogging) under each environment was also evaluated. The results are shown in Table 2.

  From Table 2, it can be seen that the sample of the present invention has high sensitivity and high tolerance for fluctuations in environmental humidity conditions.

Claims (3)

In a photothermographic material containing an organic silver salt, a photosensitive silver halide, and a silver ion reducing agent on a support, at least one of the silver ion reducing agent is represented by the following general formula (1): A heat-developable photosensitive material.

[Wherein, R ₀ ′ and R ₀ ″ represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, Q ₀ represents a substitutable group on the benzene ring, and n and m are 0-2. A plurality of Q _{0 s} may be the same or different, R _x represents a hydrogen atom or an alkyl group, R ₁ is a hydrogen atom, or R ₄ is necessary for bonding to each other to form a ring. R ₂ represents a hydrogen atom, a halogen atom, a substituent having 0 or 1 carbon atoms and containing at least one atom selected from an oxygen atom, a sulfur atom or a nitrogen atom, or a substituent having 2 or more carbon atoms R ₃ represents a hydrogen atom, a halogen atom, or a substituent, and R ₄ represents a hydrogen atom, a halogen atom, a substituent, or an atomic group necessary for bonding to R ₁ to form a ring. R ₅ represents a hydrogen atom or a methyl group.] 2. The photothermographic material according to claim 1, further comprising a nucleating agent. An image recording method comprising exposing the photothermographic material according to claim 1 or 2 using a laser scanning exposure machine having an oscillation wavelength of 600 nm to 1100 nm.