JPH11258726A - Heat developable photosensitive material, its treatment and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stability in the photographic performance during storage of a heat developable photosensitive material, to improve stability of an image on a photosensitive material after developed, and moreover, to improve stability of the photographic performance of a photosensitive material with respect to temp. change during heat development. SOLUTION: This heat developable photosensitive material contains org. silver salts, photosensitive silver halide particles, a reducing agent of silver ion, and a binder on a supporting body. The silver iodide content of the photosensitive silver halide particle is higher on the particle surface than in the inner part of the particle. The difference of the silver iodide content between in the inner part and on the surface of the photosensitive silver halide particle is controlled to between >=0.1 mol.% and <=40 mol.%. The distribution of silver iodide content in the photosensitive silver halide particle is preferably <=35% among the particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photothermographic material having excellent storage stability, particularly to a black-and-white photothermographic material, a processing method thereof, and an image forming method.

[0002]

2. Description of the Related Art In the medical field and the printing plate-making field, waste liquids caused by wet treatment of image forming materials have become a problem in terms of workability. There is a strong demand for weight loss. Therefore, there is a need for a technology relating to photothermographic materials for photographic technology, which enables efficient exposure with a laser imager and a laser imagesetter and can form a high-resolution, clear black image. As this technique, for example, US Pat. Nos. 3,152,904 and 3,487,
No. 075 and D.C. "Dry Silver Photographic Mater" by Morgan
ials) '' (Handbook of Imaging Materials, Marcel Dekke
r, Inc., page 48, 1991) is well known. Since these photosensitive materials are developed at a high temperature of 80 ° C. or higher, they are called photothermographic materials. Since these photothermographic materials do not use any solution processing chemicals,
It is possible to provide a user with a system that is simpler and does not damage the environment.

[0003] A photothermographic material containing photosensitive silver halide particles comprises a support containing photosensitive silver halide particles, an organic silver salt, a reducing agent, and a binder.

However, conventionally, in these photothermographic materials, the silver source of the photosensitive silver halide grains and the organic silver salt is reduced by a reducing agent during storage and / or at the time of storage after the heat development process, so that metallic silver is precipitated. There are drawbacks such as high fogging and the like, and improvement in storage stability has been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the stability of photographic performance of a heat-developable photosensitive material when stored over time, and to improve the stability of an image after development processing of the photosensitive material. It is still another object of the present invention to provide a photothermographic material capable of improving the stability of photographic performance with respect to temperature fluctuation during thermal development of the photothermographic material, a processing method thereof, and an image forming method.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the present invention has been accomplished. salt,
In a photothermographic material containing a silver ion reducing agent and a binder for a photosensitive silver halide grain, the silver iodide content of the photosensitive silver halide grain is higher at the grain surface than inside the grain. Photothermographic material.

According to a second aspect of the present invention, the difference between the silver iodide content inside the photosensitive silver halide grains and the silver iodide content on the grain surface is 0.1 mol% or more and 40 mol% or less. The photothermographic material according to claim 1, wherein A third aspect of the present invention is a photothermographic material containing an organic silver salt, photosensitive silver halide grains, a reducing agent for silver ions and a binder on a support. 3. The photothermographic material according to claim 1, wherein the distribution of the content between the particles is 35% or less. The invention according to claim 4 is a heat-developable photosensitive material containing an organic silver salt, photosensitive silver halide particles, a reducing agent for silver ions, and a binder on a support, wherein the photosensitive silver halide particles have the following general formula: 4. Prepared in the presence of a compound of formula (1), characterized in that:
The photothermographic material according to any one of the above. 6. The invention according to claim 5, wherein RI is a monovalent organic acid residue which releases iodide ions by reaction with a base and / or a nucleophile. 5. The photothermographic material according to claim 1, wherein the photosensitive silver halide particles have infrared sensitivity. According to a sixth aspect of the present invention, there is provided a method for processing a photothermographic material, wherein the photosensitive material according to any one of the first to fifth aspects is thermally developed at a processing temperature of 80 ° C. or higher. According to a seventh aspect of the present invention, there is provided an image forming method comprising: exposing the photosensitive material according to the fifth aspect to infrared light; and thermally developing the photosensitive material at a processing temperature of 80 ° C. or higher to obtain an image.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the photosensitive silver halide grains of the present invention, silver iodobromide, silver iodochloride, silver chloroiodobromide and the like can be used as silver halide.

In the present invention, the photosensitive silver halide grains contain silver iodide. The silver iodide content was 0.1 mol% as an average silver iodide content in the whole silver halide grains.
Is preferably at least 40 mol% and at most 0.1 mol% and at most 20 mol%.
Mole% or less is more preferable. Furthermore, 0.1 mol% or more 1
0 mol% or less is preferable, and 0.1 mol% or more and 5 mol% or less are most preferable.

In the present invention, the photosensitive silver halide grains contain silver iodide on the surface of the grains. The silver iodide content on the grain surface is preferably from 0.1 mol% to 40 mol%, more preferably from 0.5 mol% to 15 mol%,
Most preferably, it is at least 1.0 mol% and at most 10 mol%.

Here, the silver halide composition on the surface of the silver halide grains is defined by an XPS method (X-ray Photoelectron Spectrum).
(roscopy: X-ray photoelectron spectroscopy) refers to the silver halide composition in a portion up to a depth of about 5 nm, which can be determined as follows.

The sample was cooled to -110 ° C. or less in an ultra-high vacuum of 1 × 10 ⁻⁸ torr or less, and MgKα was used as a probe X-ray with an X-ray source voltage of 15 kv and an X-ray source current of 40 mA.
And measure about Ag3d5 / 2, Br3d, and I3d3 / 2 electrons. The measured integrated intensity of the peak is corrected by a sensitivity factor, and the silver halide composition on the surface is determined from the ratio of these intensities.

The purpose of cooling the sample is to eliminate measurement errors caused by destruction of the sample by X-ray irradiation at room temperature (decomposition of silver halide and diffusion of halide (particularly iodine)), and to increase measurement accuracy. By cooling to −110 ° C., sample destruction can be suppressed to a level that does not hinder measurement.

In the present invention, the photosensitive silver halide grains preferably have a silver iodide localized phase near the surface and / or near the apex. The term “near the surface” as used in the present invention refers to a position within 1/5, preferably 1/7, of the particle size as measured from the particle surface.

[0015] In the present invention, the term "near a vertex" means that one side is a length of about one third of the diameter of a circle having the same area as the area of the projected silver halide grain in the present invention, and the vertex of the grain is one point. It is within the area of the particle as one corner.

The silver iodide content of the localized silver iodide phase near the surface and / or near the apex is preferably from 0.1 mol% to 5 mol%.

In the present invention, it is important that the silver halide composition of the photosensitive silver halide grains is different between the inside and the surface, and that the silver iodide content on the surface is higher than the silver iodide content on the inside. . The difference between the internal and surface content is 0.1 mol%
Not less than 40 mol%, preferably not less than 0.5 mol% and not more than 15 mol%.
Mol% or less, more preferably 1.0 mol% or more and 10 mol% or less. Further, the silver halide composition at that time may be changed stepwise or continuously.

Here, the silver halide composition distribution of the silver halide grains can be determined by pretreating the grains into ultrathin sections and then observing and analyzing them with a transmission electron microscope while cooling. Specifically, silver halide grains are taken out of the emulsion, embedded in a resin, and cut with a diamond knife to produce a 60 μm-thick section. This section can be obtained by observation and point analysis with a transmission electron microscope equipped with an energy dispersive X-ray analyzer while cooling the section with liquid nitrogen, and by quantitative calculation (Inoue, Nagasawa: Photographic Society of Japan, 1987) Conference Abstracts 62 pages).

In the present invention, the distribution of the silver iodide content of the photosensitive silver halide grains among the grains is preferably 35% or less. It is more preferably at most 20%, further preferably at most 10%, most preferably at most 5%.

In the present invention, the silver halide composition of each silver halide grain and the average silver halide composition are determined by EP
It can be determined by using the MA method (Electron Probe Micro Analyzer method). This method produces a sample in which emulsion grains are well dispersed so as not to contact each other,
An X-ray analysis is performed by irradiating an electron beam and exciting with an electron beam, and element analysis of a very small portion can be performed. By determining the characteristic X-ray intensity of silver and halogen emitted from each grain by this method, the silver halide composition of each grain can be determined. EPM for at least 50 particles
If the silver halide composition is determined by the Aμ method, the average silver halide composition is determined from the average thereof. The distribution of the silver iodide content between grains is obtained by (intergranular distribution of silver iodide content) = (standard deviation of silver iodide content) / (average value of silver iodide content) × 100. Can be.

The photothermographic material of the present invention basically contains a photosensitive silver halide, a non-photosensitive reducible silver source, and a reducing agent for the silver source. This forms a photographic image. For details of the photothermographic material, see, for example, U.S. Pat. Nos. 3,152,904 and 3,45.
7,075, and D.C. "Dry Silver Photographic Mater" by Morgan
ial) "and D.E. Morgan and B.A. "The Silver System Treated by Heat (T
hermally Processed SilverSystems "(Imaging Pr
ocesses and Materials) Neblette 8th edition, Sturge, V.S. Walworth, A .; Shepp, page 2, 1969).

The photosensitive silver halide grains in the present invention will be described. In the present invention, the average particle size is preferably small in order to suppress white turbidity after image formation and obtain good image quality.
2 μm or less, more preferably 0.01 μm to 0.17 μm
m, particularly preferably 0.02 μm to 0.14 μm. The term "grain size" as used herein refers to the length of a ridge of a silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case where the silver halide grains are tabular grains, the diameter refers to a diameter when converted into a circular image having the same area as the projected area of the main surface.

The silver halide is preferably monodispersed. Here, the monodispersion means that the degree of monodispersion determined by the following formula is 40% or less. The particles are more preferably 30% or less, particularly preferably 0.1% or more and 20% or less.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100

The shape of the silver halide grains is cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned, and in the present invention, cubic particles and tabular particles are particularly preferable. When tabular silver halide grains are used, the average aspect ratio is preferably from 2 to 100, more preferably from 3 to 50. These are described in U.S. Pat. Nos. 5,264,337, 5,314,798, and 5,320,958, and can easily obtain target tabular grains. Further, grains having rounded corners of silver halide grains can also be preferably used. The outer surface of the silver halide grains is not particularly limited, but has a Miller index [100].
It is preferable that the proportion occupied by the surface is high.
%, More preferably 70% or more, particularly preferably 80% or more. The ratio of the Miller index [100] plane is determined by T. Tani, J. Imaging Sci., 29, 165 (1985) using the dependence of the adsorption of the sensitizing dye on the [111] plane and the [100] plane.
Can be obtained by The silver halide grains used in the present invention are described in Chimie et Physique Phot by P. Glafkides.
ographique (Paul Montel, 1967), GFDuffin Ph
otographic Emulsion Chemistry (The Focal Press, 196
6 years), Making and Coating Photog by VLZelikman et al
It can be prepared using the method described in raphic Emulsion (The Focal Press, 1964) and the like. That is, any of an acidic method, a neutral method, an ammonia method, etc. may be used.
Any of a one-side mixing method, a simultaneous mixing method, a combination thereof and the like may be used. As a method for increasing the silver iodide content on the surface of silver halide, fine grains of silver iodide, fine grains may be added in the late stage of crystal growth and / or in an emulsion containing silver halide grains serving as a base on which crystal growth has been completed. A method of adding at least one fine grain silver halide emulsion among silver iodobromide, fine grain silver iodochloride, and fine grain silver iodochlorobromide, a method of adding an aqueous alkali iodide solution, a method of using an iodide ion releasing agent, and the like. Preferably applicable. Of these, a method of adding an aqueous solution of an alkali iodide and a method of using an iodide ion releasing agent are preferable, and a method of using an iodide ion releasing agent is most preferable.

In the present invention, it is preferable to use a compound represented by the following general formula (1) as an iodide ion releasing agent.

Formula (1) RI

In the formula, R represents a monovalent organic acid residue which releases iodide ions by reaction with a base and / or a nucleophile.

R is, for example, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms, a heterocyclic group, Preferred are an acyl group of 30 to 30, a carbamoyl group, an alkyl or aryl sulfonyl group having 2 to 30 carbon atoms, and a sulfamoyl group. The carbon number of R is particularly preferably 12 or less. Further, R is preferably substituted, and preferred substituents include the following.

Halogen atoms (eg, fluorine, chlorine, bromine, iodine) and alkyl groups (eg, methyl, ethyl, n-
Propyl, i-propyl, t-butyl, n-octyl,
Cyclopentyl, cyclohexyl), alkenyl group (eg, allyl, 2-butenyl, 3-pentenyl), alkynyl group (eg, propargyl, 3-pentynyl), aralkyl group (eg, benzyl, phenethyl), aryl group (eg, phenyl, naphthyl, 4-phenyl) Methylphenyl),
Heterocyclic groups (eg, pyridyl, furyl, imidazolyl, piperidyl, morpholyl), alkoxy groups (eg, methoxy, ethoxy, butoxy), aryloxy groups (eg, phenoxy, naphthoxy), amino groups (eg, unsubstituted amino, dimethylamino, ethylamino) , Anilino), acylamino group (eg, acetylamino, benzoylamino), ureido group (eg, unsubstituted ureido, N-methylureido, N-phenylureido), urethane group (eg, methoxycarbonylamino, phenoxycarbonylamino), sulfonylamino group (Eg, methylsulfonylamino, phenylsulfonylamino), sulfamoyl group (eg, sulfamoyl, N-methylsulfamoyl, N-phenylsulfamoyl), carbamoyl group (eg, carbamoyl) Diethylcarbamoyl, phenylcarbamoyl), sulfonyl group (eg, methylsulfonyl, benzenesulfonyl), sulfinyl group (eg, methylsulfinyl, phenylsulfinyl), alkyloxycarbonyl group (eg, methoxycarbonyl, ethoxycarbonyl), aryloxycarbonyl group (eg, phenoxycarbonyl) ), Acyl groups (eg, acetyl, benzoyl, formyl, pivaloyl), acyloxy groups (eg, acetoxy, benzoyloxy), phosphoramide groups (eg, N, N-diethylphosphoramide), alkylthio groups (eg, methylthio, ethylthio), arylthio groups (For example, phenylthio), cyano group, sulfo group,
A carboxyl group, a hydroxy group, a phosphono group, and a nitro group.

Further preferred substituents are a halogen atom,
Alkyl group, aryl group, 5- or 6-membered heterocyclic group containing at least one hetero atom of an oxygen atom, a nitrogen atom or a sulfur atom, an alkoxy group, an aryloxy group, an acylamino group, a sulfamoyl group, a carbamoyl group, an alkyl group A sulfonyl group, an arylsulfonyl group, an aryloxycarbonyl group, an acyl group, a sulfo group, a carboxyl group, a hydroxy group and a nitro group.

Particularly preferred substituents are a hydroxy group, a carbamoyl group, a lower alkylsulfonyl group or a sulfo group (including salts thereof) when substituted with an alkylene group, and a sulfo group (salts thereof) when substituted with a phenylene group. ).

The compound of the general formula (1) releases an iodide ion by reaction with a base or a nucleophile. The iodide ion may be an iodide ion itself, or may be an iodine ion and another organic compound. It may be an iodine ion bonded to a group.

The compound of the present invention can be prepared, for example, by the method described in J. Am.
c., 76, 3227-8 (1954), J. Org. Chem., 16,798 (1951), Chem. B
er., 97, 390 (1964), Org. Synth., V. 478 (1973), J. Chem. So
c., 1951,1851, J.Org.Chem., 19,1571, (1954), J.Chem.So
c., 1955, 1383 and Chem. Commu., 1971, 1112, which can be easily synthesized with reference to these.

The compound represented by the general formula (1) reacts with a base or a nucleophile as an iodide ion release regulator to release iodide ions. The base or nucleophile used in this case is preferably used. Include the following chemical species. For example, hydroxyl ions, sulfite ions, hydroxylamine, thiosulfate ions, mercaptans, sulfinates, carboxylate salts, alcohols, ureas, thioureas, phenols, hydrazines, hydrazides, phosphines, sulfides And the like.

The release rate and timing of iodide ions can be controlled by controlling the concentrations of bases and nucleophiles, the method of addition, and the temperature of the reaction solution.

The preferred concentration range of the iodine ion releasing agent represented by the general formula (1) is 1 to 1 mol per mol of silver halide.
× 10 ⁻⁵ to 10 mol, more preferably 1 × 10 ⁻⁴ to
5 moles.

The preferred temperature range for controlling the iodine ion release rate and timing is 30 to 80 ° C., more preferably 35 to 60 ° C.

At a temperature higher than 80 ° C., the release rate of iodide ions is generally extremely high, and at a low temperature lower than 30 ° C., the release rate of iodide ions is extremely slow.

In the present invention, when a base is used for releasing iodide ions, a change in pH of the solution may be used. At this time, the preferable pH range for controlling the iodine ion release rate and timing is 2 to 12, and more preferably 5 to 10.

A nucleophile and a base may be used in combination.
At this time, the pH may be controlled in the above range to control the iodine ion release rate and timing.

When releasing iodine ions from the iodide ion releasing agent, all iodine atoms may be released or some iodine atoms may remain without being decomposed.

In the present invention, the release rate of iodide ions can be determined by controlling the temperature, pH, concentration of an iodide ion releasing agent, a base, and a nucleophile as described above. You can choose the speed.

For controlling iodine ions in the present invention, the following method is preferable. That is, by changing the pH, the concentration of the nucleophile, the temperature, and the like from the iodide ion releasing agent added to the reaction solution and already uniformly distributed, usually, the change from low pH to high pH causes iodine ion release. Is released while uniformly controlling the entire reaction solution.

The base and / or nucleophile for controlling the reaction rate of release of iodide ions may be present in the reaction solution before the addition of the iodide ion releasing agent. It is preferable to add in a distributed state.

Hereinafter, specific examples of the compound represented by formula (1) of the present invention will be shown, but the present invention is not limited to these compounds.

[0047]

Embedded image

[0048]

Embedded image

[0049]

Embedded image

[0050]

Embedded image

[0051]

Embedded image

[0052]

Embedded image

[0053]

Embedded image

In the present invention, when a fine grain silver halide emulsion is added after crystal growth, and when an iodide ion releasing agent is used, it is preferable to increase the solubility of silver halide grains serving as a substrate. For this purpose, it is preferable to use a method such as raising the temperature of an emulsion containing silver halide grains to be a substrate, changing pAg, changing pH, or adding a silver halide solvent.

When the temperature is increased, the temperature should be 3 to
30 ° C is preferred, and 7 to 20 ° C is more preferred. pAg
Although the preferred range varies depending on the halogen composition, crystal habit and other conditions, it can be adjusted to a preferred range by adding an aqueous halide solution or adding a water-soluble silver salt. Also,
The pH can be adjusted to a preferable range by an appropriate acid or alkali. As the silver halide solvent, it is preferable to use a known silver halide solvent such as ammonia, thioether, thiourea, and thiocyanate.

The silver halide may be added to the image forming layer by any method, and the silver halide is arranged so as to be close to the reducible silver source. Further, the silver halide may be prepared by converting a part or all of the silver in the organic acid silver by the reaction of the organic acid silver and the halogen ion into silver halide, or may be prepared by preparing silver halide in advance. In advance, this may be added to a solution for preparing an organic silver salt, or a combination of these methods is possible, but the latter is preferred. Generally, the silver halide is preferably contained in an amount of 0.75 to 30% by weight based on the organic silver salt.

The silver halide grains used in the present invention preferably contain a metal complex selected from the group consisting of Fe, Co, Ru, Rh, Re, Os, Ir and the like. Two or more metal complexes may be used in combination. The preferred content is 1 × 10 ⁻⁹ per mole of silver.
Mole to 1 × 10 ⁻² mole, preferably 1 × 10 ² mole.
The range of ^-8 mol to 1 x ^10-4 is more preferred. In the present invention, the transition metal complex is preferably a six-coordinate complex represented by the following general formula.

The general formula [ML ₆ ] ^m

In the formula, M is a group VIB of the periodic table of elements, VII
A transition metal selected from Group B, VIII, and IB elements, L represents a bridging ligand, and m represents 0, -1, -2, or -3.

Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and alcohol. Each ligand of
Nitrosyl, thionitrosyl and the like can be mentioned, and preferred are aquo, nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

The following are specific examples of the transition metal coordination complex.

1: [RhCl₆]^3- 2: [RuCl₆]^3- 3: [ReCl₆]^3- 4: [RuBr₆]^3- 5: [OsCl₆]^3- 6: [CrCl₆]^Four- 7: [IrCl₆]^Four- 8: [IrCl₆]^3- 9: [Ru (NO) Cl_Five]^2- 10: [RuBr_Five(H_TwoO)]^2- 11: [Ru (NO) (H_TwoO) Cl_Four]^- 12: [RhCl_Five(H_TwoO)]^2- 13: [Re (NO) Cl_Five]^2- 14: [Re (NO) CN_Five]^2- 15: [Re (NO) ClCN_Four]^2- 16: [Rh (NO)_TwoCl_Four]^- 17: [Rh (NO) (H_TwoO) Cl_Four]^- 18: [Ru (NO) CN_Five]^2- 19: [Fe (CN)₆]^3- 20: [Fe (CN) ₆]^Four- 21: [Co (CN)₆]^3- 22: [Rh (NS) Cl_Five]^2- 23: [Os (NO) Cl_Five]^2- 24: [Cr (NO) Cl_Five]^2- 25: [Re (NO) Cl_Five]^- 26: [Os (NS) Cl_Four(TeCN)]^2- 27: [Ru (NS) Cl _Five]^2- 28: [Re (NS) Cl_Four(SeCN)]^2- 29: [Os (NS) Cl (SCN)_Four]^2- 30: [Ir (NO) Cl_Five]^2-

The compound which provides these metal ions or complex ions is preferably added during silver halide grain formation and incorporated into silver halide grains. Preparation of silver halide grains, that is, nucleation and growth , Physical aging,
Although it may be added at any stage before and after chemical sensitization, it is particularly preferable to add at the stage of nucleation, growth, and physical ripening,
Further, it is preferably added at the stage of nucleation and growth, most preferably at the stage of nucleation. In the addition, it may be added in several divided portions, and may be uniformly contained in the silver halide grains.
3-29603, JP-A-2-306236 and 3-
Nos. 167545, 4-76534, 6-1101
As described in JP-A Nos. 46 and 5-273683, they can be contained in the particles with a distribution. Preferably, a distribution can be provided inside the particles. These metal compounds can be added by dissolving them in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a silver salt solution and a halide solution are mixed at the same time. To prepare silver halide grains by a method of simultaneous mixing of three liquids, a method of charging a required amount of an aqueous solution of a metal compound into a reaction vessel during grain formation, or a method of preparing silver halide. There is a method in which another silver halide grain doped with a metal ion or a complex ion in advance is sometimes added and dissolved. In particular, an aqueous solution of a metal compound powder or a metal compound and NaCl, KC
A preferred method is to add an aqueous solution in which 1 is dissolved together with a water-soluble halide solution. When adding 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 or at the end of physical ripening, or at the time of chemical ripening.

The photosensitive silver halide grains can be desalted by a known desalting method such as a noodle method, flocculation method, ultrafiltration method, and electrodialysis method.

The photosensitive silver halide grains in the present invention are preferably chemically sensitized. Examples of the sensitization method include known methods such as sulfur sensitization, selenium sensitization, tellurium sensitization, noble metal sensitization, and reduction sensitization. A sensitization method can be used. These sensitization methods can be used in combination of two or more. For sulfur sensitization, thiosulfates, thiourea compounds, inorganic sulfur and the like can be used. Compounds preferably used for selenium sensitization and tellurium sensitization are described in JP-A-9-2.
No. 30527 can be mentioned. Compounds preferably used in the noble metal sensitization method are described, for example, in chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, and US Pat. No. 2,448,060 and British Patent No. 6,180,61. Compounds can be mentioned. Specific compounds used in the reduction sensitization method include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, and the like. Further, reduction sensitization can be achieved by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less.

The photothermographic material of the present invention contains cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes as spectral sensitizing dyes.
A holopolar cyanine dye, styryl dye, hemicyanine dye, oxonol dye, hemioxonol dye, and the like can be used. For example, Japanese Unexamined Patent Application Publication No.
No., 60-140335, 63-231437
No., 63-259,651 and 63-304242
No. 63-15245, U.S. Pat. No. 4,639,4
No. 14, No. 4,740,455, No. 4,741,
No. 966, No. 4,751,175, No. 4,83
Sensitizing dyes described in U.S. Pat. No. 5,096 can be used. Useful sensitizing dyes for use in the present invention include, for example, Research Discl.
osure Item17643IV-A (p.23, December 1978), Item1831X
(August 1978, p. 437). In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers and scanners can be advantageously selected. For example, JP-A-9-3
Compounds described in Nos. 4078, 9-54409 and 9-80679 are preferably used.

The cyanine dye useful in the present invention is, for example, a cyanine dye having a basic nucleus such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus. Preferred useful merocyanine dyes include, in addition to the basic nuclei described above, a thiohydantoin nucleus,
Also includes acidic nuclei such as rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus.

In the present invention, it is particularly preferable to use a sensitizing dye having spectral sensitivity in the infrared.

The sensitizing dye having a spectral sensitivity in the infrared rays preferably contains at least one compound represented by the following general formulas [Ia] to [Id].

[0070]

Embedded image

[In the general formulas [Ia] to [Id], Z ₁₁ , Z ₁₂ , Z ₂₁ , Z ₂₂ , Z ₃₁ , Z ₄₁
And Z ₄₂ each represent a non-metal atom group required to complete a monocyclic or condensed 5- or 6-membered nitrogen-containing heterocyclic ring, and Q ₃₁ , Q ₃₂ and Q ₄₁ each represent oxygen Represents an atom, a sulfur atom, a selenium atom or —N (R) —, wherein R represents an alkyl group, an aryl group or a heterocyclic group.
R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ , R ₃₁ , R ₄₁ and R ₄₃ each represent an aliphatic group, and R ₃₂ , R ₃₃ and R ₄₂ each represent an alkyl group, an aryl group or a heterocyclic ring Represents a group. R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ , R
₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R
₂₉ , _R34 , _R35 , _R36 , _R37 , _R38 , R
₃₉ , R ₄₄ , R ₄₅ , R ₄₆ , R ₄₇ , R ₄₈ and R
₄₉ represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, an aryloxy group, an aryl group, -N (W1, W2)-, -SR or a heterocyclic group, respectively. Here, R represents an alkyl group, an aryl group or a heterocyclic group, W ₁ and W ₂ each represent a substituted or unsubstituted alkyl group or an aryl group, and W ₁ and W ₂ are connected to each other to form a 5-membered or It can also form a 6-membered nitrogen-containing heterocycle. R ₁₁ and R ₁₃ , R ₁₄ and R ₁₆ , R ₁₇ and R
₁₂ , R ₂₁ and R ₂₃ , R ₂₄ and R ₂₆ , R ₂₅ and R
₂₇ , R ₂₆ and R ₂₈ , R ₂₂ and R ₂₉ , R ₃₁ and R
₃₄ , _R35 and _R37 , _R41 and _R44 , _R45 and R
₄₇ and R ₄₉ and R ₄₃ can be linked together to form a 5- or 6-membered ring. X ₁₁ , X ₂₁ and X ₄₁
Each represents an ion required to cancel an intramolecular charge, and m ₁₁ , m21, and m ₄₁ each represent the number of ions required to cancel an intramolecular charge. n ₁₁ ,
n ₁₂ , n ₂₁ , n ₂₂ , n ₃₁ , n ₄₁ and n ₄₂ each represent 0 or 1, and l ₃₁ , l ₃₂ , l ₃₃ , l
₄₁ , l ₄₂ and l ₄₃ each represent 0 or 1. ]

The compound represented by the general formula [Ia] is preferably a compound represented by the following general formula [Ie] or [If].

[0073]

Embedded image

[General formula [Ie] and general formula [If]]
, Y ₅₁ , Y ₅₂ , Y ₆₁ and Y ₆₂ are respectively
Represents an oxygen atom, a sulfur atom, a selenium atom or — (NR ₀ ) —, wherein R ₀ represents an aliphatic group. R ₅₁ and R ₅₂
Each represents an aliphatic group, and R ₆₁ represents an aliphatic group or R ₆₅
Represents a group of non-metallic atoms necessary for completing a 5- or 6-membered condensed ring. R ₅₃ and R ₅₄ each represent a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group;
₅₅ and R ₆₂ each represent a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group or an amino group, and R ₆₃ and R ₆₄ each represent a hydrogen atom Represents an atom, an alkyl group or a group of non-metallic atoms necessary for forming a 5- or 6-membered ring by bonding between R ₆₃ and R ₆₄ . R ₆₅
Represents a hydrogen atom or a bond to R61. A _{51 to} A
₅₈ and A _{61 to} A ₆₈ each represent a hydrogen atom or a substitutable group, and A ₅₁ and A ₅₂ , A ₅₂ and A ₅₃ , A ₅₃
And A ₅₄ , A ₅₅ and A ₅₆ , A ₅₆ and A ₅₇ , A ₅₇ and A _58, A ₆₁ and A ₆₂ , A ₆₂ and A ₆₃ , A ₆₃ and A ₆₄ , A ₆₅ and A ₆₆ , A ₆₅ and A ₆₆ , A ₆₆ and A ₆₇ , A ₆₇ and A
_At least one set of ₆₈ may be linked together to form a fused naphthol ring. M ₅₁ and M ₆₁ are each
Represents an ion required to cancel the charge in the molecule, and m ₅₁
And m ₆₁ each represent the number of ions required to offset the charge in the molecule. p represents 2 or 3. ]

The compound represented by the general formula [Ib] is preferably a compound represented by the following general formula [Ig], [Ih] or [Ii].

[0076]

Embedded image

[General formula [Ig], [Ih] or [I
-I], Y ₇₁ , Y ₇₂ , Y ₈₁ , Y ₈₂ , Y
₉₁ and Y ₉₂ each represent an oxygen atom, a sulfur atom, a selenium atom or-(NR0)-, wherein R0 represents an aliphatic group. R ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₉₁ and R
₉₂ represents an aliphatic group. R ₇₃ and R ₇₄ and R
₉₃ and R ₉₄ each represent a group of nonmetallic atoms necessary to bond to each other to form a 5- or 6-membered ring, and R ₇₅ and R ₉₅ each represent a hydrogen atom, an alkyl group, an aryl group,
Represents a heterocyclic group, a halogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group or an amino group. A _{71 to} A ₇₈ , A _{81 to} A ₈₈ and A _{91 to} A
₉₈ represents a hydrogen atom or a displaceable group, and A ₇₁
And A ₇₂ , A ₇₂ and A ₇₃ , A ₇₃ and A ₇₄ , A ₇₅ and A ₇₆ , A ₇₆ and A ₇₇ , A ₇₇ and A _78, A ₈₁ and A ₈₂ , A ₈₂ and A ₈₃ , A ₈₃ and A ₈₄ , A ₈₅ and A
₈₆ , A ₈₆ and A ₈₇ , A ₈₇ and A ₈₈ and A ₉₁ and A
₉₂ , A ₉₂ and A ₉₃ , A ₉₃ and A ₉₄ , A ₉₅ and A
_{96, A 96} and _{A 97, A 97} and at least one pair of _{A 98} may be linked to form a fused naphthol ring. M ₇₁ , M ₈₁ and M ₉₁ each represent an ion required to cancel the charge in the molecule, and m ₇₁ , m ₈₁ and m ₉₁ each denote the number of ions required to cancel the charge in the molecule. Represent. ]

Hereinafter, the sensitizing dyes represented by formulas [Ia] to [Id] and [Ie] or [Ii] will be described in detail.

In the above general formulas [Ia] to [Id], Z ₁₁ , Z ₁₂ , Z ₂₁ , Z ₂₂ , Z ₃₁ , Z ₄₁
And a 5-membered or 6-membered nitrogen-containing heterocyclic ring represented by Z ₄₂ , respectively, such as an oxazole nucleus (for example, an oxazolidine ring, an oxazoline ring, a benzoxazole ring, a tetrahydrobenzoxazole ring, a naphthooxazole ring, a benzonaphthoxazole ring, etc.) An imidazole nucleus (e.g., an imidazolidine ring, an imidazoline ring, a benzimidazole ring, a tetrahydrobenzimidazole ring, a naphthoimidazole ring, a benzonaphthoimidazole ring, etc.), a thiazole nucleus (e.g., a thiazolidine ring, a thiazoline ring,
Benzothiazole ring, tetrahydrobenzothiazole ring, naphthothiazole ring, benzonaphthothiazole ring, etc., selenazole nucleus (for example, selenazolidine ring, selenazoline ring, benzoselenazole ring, tetrahydrobenzoselenazole ring, naphthoselenazole ring, benzonaphthoselena) A azole ring), a tellurazole nucleus (eg, a tellurazolidine ring, a tellurazoline ring, a benzotellurazole ring, etc.), a pyridine nucleus (eg, pyridine, quinoline, etc.), a pyrrole nucleus (eg, a pyrrolidine ring, a pyrroline ring, a pyrrole ring, 3, 3-dialkylindolenine ring, etc.), and A _{1 to} A ₉₈ described below are provided on these rings.
Any group described as a substitutable group represented by can be substituted.

R ₀ , R ₁₁ , R ₁₂ , R ₂₁ , R ₂₂ ,
R ₃₁ , R ₄₁ , R ₄₃ , R ₅₁ , R ₅₂ , R ₆₁ , R
Examples of the aliphatic group represented by ₇₁ , R ₇₂ , R ₈₁ , R ₈₂ , R ₉₁ and R ₉₂ include, for example, those having 1 to 1 carbon atoms.
0 branched or straight-chain alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, iso-
Pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, etc.), alkenyl group having 3 to 10 carbon atoms (for example,
2-propenyl group, 3-butenyl group, 1-methyl-3-
A propenyl group, a 3-pentenyl group, a 1-methyl-3-butenyl group, a 4-hexenyl group and the like, and an aralkyl group having 7 to 10 carbon atoms (eg, a benzyl group and a phenethyl group).

The above-mentioned groups further include a lower alkyl group (eg, a methyl group, an ethyl group, a propyl group, etc.), a halogen atom (eg, a fluorine atom, a chlorine atom, a bromine atom, etc.),
Vinyl group, aryl group (for example, phenyl group, p-tolyl group, p-bromophenyl group, etc.), trifluoromethyl group, alkoxy group (for example, methoxy group, ethoxy group,
Methoxyethoxy group etc.), aryloxy group (for example,
Phenoxy group, p-tolyloxy group, etc.), cyano group, sulfonyl group (eg, methanesulfonyl group, trifluoromethanesulfonyl group, p-toluenesulfonyl group, etc.), alkoxycarbonyl group (eg, ethoxycarbonyl group, butoxycarbonyl group, etc.) An amino group (eg, an amino group, a biscarboxymethylamino group, etc.), an aryl group (eg, a phenyl group, a carboxyphenyl group, etc.), a heterocyclic group (eg, tetrahydrofurfuryl,
-Pyrrolidinone-1-yl group and the like), acyl group (for example,
Acetyl group, benzoyl group, etc.), ureido group (for example,
Ureido group, 3-methylureido group, 3-phenylureido group, etc.), thioureido group (eg, thioureido group, 3-methylthioureido group, etc.), alkylthio group (eg, methylthio, ethylthio group, etc.), arylthio group (eg, A phenylthio group, etc.), a heterocyclic thio group (e.g., a 2-thienylthio group, a 3-thienylthio group, etc.),
Carbonyloxy group (eg, acetyloxy group, propanoyloxy group, benzoyloxy group, etc.), acylamino group (eg, acetylamino, benzoylamino group, etc.), thioamide group (eg, thioacetamido group, thiobenzoylamino group, etc.) Groups, or, for example,
Sulfo group, carboxy group, phosphono group, sulfate group, hydroxy group, mercapto group, sulfino group, carbamoyl group (for example, carbamoyl group, N-methylcarbamoyl group, N, N-tetramethylenecarbamoyl group, etc.), sulfamoyl group (for example, , A sulfamoyl group,
N, N-3-oxpentamethyleneaminosulfonyl group, etc.), sulfonamide group (eg, methanesulfonamide, butanesulfonamide group, etc.), sulfonylaminocarbonyl group (eg, methanesulfonylaminocarbonyl, ethanesulfonylaminocarbonyl group, etc.) ), An acylaminosulfonyl group (eg, acetamidosulfonyl, methoxyacetamidosulfonyl group, etc.), an acylamicarbonyl group (eg, acetamidocarbonyl, methoxyacetamidocarbonyl group, etc.), a sulfinylaminocarbonyl group (eg, methanesulfinylaminocarbonyl, ethanesulfinyl) And a hydrophilic group such as aminocarbonyl group). Specific examples of the aliphatic group in which these hydrophilic groups are substituted include carboxymethyl, carboxyethyl, carboxybutyl, carboxypentyl, 3-sulfatobutyl,
Sulfopropyl, 2-hydroxy-3-sulfopropyl, 4-sulfobutyl, 5-sulfopentyl, 3-sulfopentyl, 3-sulfinobutyl, 3-phosphonopropyl, hydroxyethyl, N-methanesulfonylcarbamoylmethyl, 2- Carboxy-2-propenyl, o
-Sulfobenzyl, p-sulfophenethyl, p-carboxybenzyl and the like.

R, R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R
_{17, R 23, R 24,} R 25, R 26, R 27, R
_{28, R 29, R 32,} R 33, R 34, R 35, R
₃₆ , R ₃₇ , R ₃₈ , R ₃₉ , R ₄₂ , R ₄₄ , R
₄₅ , R ₄₆ , R ₄₇ , R ₄₈ , R ₄₉ , R ₅₃ , R
₅₄ , R ₅₅ , R ₆₂ , R ₆₃ , R ₆₄ , R ₇₅ and R
Each of the alkyl groups represented by ₉₅ includes, for example, a methyl group, an ethyl group, a butyl group, an iso-butyl group and the like, and the aryl group includes monocyclic and polycyclic ones, for example, a phenyl group, Examples include groups such as a naphthyl group, and examples of the heterocyclic group include groups such as thienyl, furyl, pyridyl, carbazolyl, pyrrolyl, and indolyl.

These groups include R ₀ , R _{11 and} R ₉₂
And the like. Examples of the substituted alkyl group include, for example, 2-methoxyethyl, 2-hydroxyethyl, 3-ethoxycarbonylpropyl, 2-carbamoylethyl Each group such as 2,2-methanesulfonylethyl, 3-methanesulfonylaminopropyl, benzyl, phenethyl, carboxymethyl, carboxyethyl, allyl, and 2-furylethyl is exemplified. Specific examples of the substituted aryl group include, for example, P-carboxyphenyl, p-N, N-dimethylaminophenyl, p-morpholinophenyl, p-methoxyphenyl, 3,4-dimethoxyphenyl, 3,4-methylenedioxyphenyl, 3-chlorophenyl, p-nitro Each group such as phenyl and the like, specific examples of the substituted heterocyclic group, In example 5-chloro-2-pyridyl, 5-ethoxycarbonyl-2-pyridyl, and each group such as 5-carbamoyl-2-pyridyl.

Examples of the alkyl group and the aryl group represented by W ₁ and W ₂ include the groups described above for R and the like.

R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ ,
R ₁₇ , R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R
_{28, R 29, R 34,} R 35, R 36, R 37, R
₃₈ , _R39 , _R44 , _R45 , _R46 , _R47 , R
_The alkoxy group represented by each of ₄₈ , R ₄₉ , R ₅₅ , R ₆₂ , R ₇₅ and R ₉₅ includes, for example, a methoxy group, an ethoxy group, a 2-methoxyethoxy group, a 2-hydroxyethoxy group and the like. Examples of the aryloxy group include a phenoxy group, 2 naphthoxy group, 1 naphthoxy group, p-tolyloxy group, p-methoxyphenyl group and the like.

The halogen atom represented by R ₅₅ , R ₆₂ , R ₇₅ and R ₉₅ is, for example, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and the alkylthio group is, for example, a methylthio group, an ethylthio group. And the like.Examples of the arylthio group include a phenylthio group and an m-chlorophenylthio group.Examples of the amino group include substituted and unsubstituted groups, for example, an amino group, a methylamino group, a dimethylamino group, Examples thereof include a diethylamino group, a diphenylamino group, an N, N-tetramethyleneamino group, and an N, N-pentamethyleneamino group.

R ₁₄ and R ₁₆ , R ₂₄ and R ₂₆ , R ₂₅
R ₂₇ , R ₂₆ and R ₂₈ , R ₃₅ and R ₃₇ , R ₄₅ and R ₄₇ , R ₄₉ and R ₄₃ , R ₆₃ and R ₆₄ , R ₇₃ and R ₇₃
Examples of the condensed ring which can be formed by connecting ₇₄ and R ₉₃ and R ₉₄ to each other include a 5- or 6-membered saturated or unsaturated condensed carbocyclic ring. Any of these condensed rings can be substituted at any position, and examples of these substituted groups include the groups described above as the groups that can be substituted with the aliphatic group.

R ₁₁ and R ₁₃ , R ₁₇ and R ₁₂ , R ₂₁
And R ₂₃ , R ₂₂ and R ₂₉ , R ₃₁ and R ₃₄ , and R ₄₁ and R ₄₄ , each of which may be connected to each other, for example, as a 5-membered or 6-membered saturated or unsaturated ring. And a nitrogen-containing condensed ring. Examples of the 5- or 6-membered nitrogen-containing heterocyclic ring formed by connecting W ₁ and W ₂ together with a nitrogen atom include a pyrrolidine ring, a morpholine ring, and a piperidine ring.

A _{51 to} A ₅₈ , A _{61 to} A ₆₈ , A ₇₁
-A ₇₈ , A ₈₁ -A ₈₈ and A ₉₁ -A ₉₈ each represent a substitutable group such as a lower alkyl group (eg, a methyl group, an ethyl group, a propyl group, etc.), a halogen atom (eg, a fluorine atom) , A chlorine atom, a bromine atom, etc.), a vinyl group, a styryl group, an aryl group (eg, a phenyl group, a p-tolyl group, a p-bromophenyl group, etc.), a trifluoromethyl group, an alkoxy group (eg, a methoxy group,
An ethoxy group), an aryloxy group (eg, a phenoxy group, a p-tolyloxy group, etc.), a carbonyloxy group (eg, an acetyloxy group, a propanoyloxy group,
Benzoyloxy group and the like), amino group (for example, amino,
Each group such as dimethylamino and anilino), a heterocyclic group (for example, a pyridyl group, a pyrrolyl group, a furyl group, a thienyl group,
Imidazolyl group, thiazolyl group, pyrimidinyl group, etc.),
Acyl group (eg, acetyl group, benzoyl group, etc.), cyano group, sulfonyl group (eg, methanesulfonyl group,
Benzenesulfonyl group, etc.), carbamoyl group (for example,
Carbamoyl group, N, N-dimethylcarbamoyl group, morpholinocarbonyl group, etc.), sulfamoyl group (eg, sulfamoyl group, N-phenylsulfamoyl group, morpholinosulfonyl group, etc.), acylamino group (eg, acetylamino group, Benzoylamino, or
th-hydroxybenzoylamino group, etc.), sulfonylamino group (for example, methanesulfonylamino group, benzenesulfonylamino group, etc.), alkoxycarbonyl group,
(For example, methoxycarbonyl group, ethoxycarbonyl group, trifluoroethoxycarbonyl group, etc.), hydroxyl group, carboxyl group and the like.

In the compounds represented by the above general formulas [Ia] to [Ii], when a group having a cationic or anionic charge is substituted, each of the compounds is so set as to cancel the intramolecular charge. A counter ion is formed with an equivalent amount of an anion or cation. For example, X ₁₁ , X ₂₁ , X ₄₁ ,
Specific examples of cations required for canceling the intramolecular charge represented by M ₅₁ , M ₆₁ , M ₇₁ , M _81, and M ₉₁ include protons, organic ammonium ions (for example, triethylammonium). , Triethanolammonium, etc.) and inorganic cations (eg, lithium, sodium, potassium, etc. cations). Specific examples of acid anions include, for example,
Halogen ion (for example, chloride ion, bromine ion, iodine ion, etc.), p-toluenesulfonic acid ion, perchlorate ion, boron tetrafluoride ion, sulfate ion, methyl sulfate ion, ethyl sulfate ion, methanesulfonic acid ion, trifluorofluoride Methanesulfonate ion and the like.

In the sensitizing dyes represented by formulas [Ia] to [Id], the sensitizing dyes represented by formulas [Ie] and [I-
The sensitizing dyes represented by formula (f) are preferably used, and the sensitizing dyes represented by the formulas (Ig) to (Ii) are more preferably used.

The following formulas [Ia] to [I-
Representative examples of the sensitizing dyes (compounds) represented by i) are shown below, but the present invention is not limited to these compounds.

[0093]

Embedded image

[0094]

Embedded image

[0095]

Embedded image

[0096]

Embedded image

[0097]

Embedded image

[0098]

Embedded image

[0099]

Embedded image

[0100]

Embedded image

The above-mentioned infrared-sensitive sensitizing dye is described, for example, in The Chemistry of Heterocyl by FM Hammer.
ic Compounds Volume 18, The Cyanine Dyes and Relat
edCompounds (A. Weissherger ed.Interscience, New
York 1964).

The sensitizing dyes of the present invention may be used alone or in combination of two or more. When two or more sensitizing dyes (photosensitive dyes) of the present invention are used in combination, the photosensitive dyes can be dispersed in a silver halide emulsion independently or in a premixed manner by the method described above. A dye having absorption in the visible region for the purpose of supersensitization, a dye having no spectral sensitization itself, or a substance which does not substantially absorb visible light together with the photosensitive dye of the present invention, A substance exhibiting a feeling may be contained in the emulsion.

Useful photosensitive dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in Research Disclosure, Vol. 176, 17643 (December 1978).
Monthly) Page 23, IV, J, or JP-B-49-2550
No. 0, No. 43-4933, JP-A-59-19032
No. 59-192242, No. 62-123454
JP-A-3-15049, JP-A-7-146527
No. etc.

In the present invention, the organic silver salt is a reducible silver source, and a silver salt of an organic acid and a hetero organic acid containing a reducible silver ion source, particularly a long chain (preferably having 10 to 30 carbon atoms, Preferred are silver salts of aliphatic carboxylic acids 15 to 28). Organic or inorganic silver salt complexes wherein the ligand has a complex stability constant for silver ions of 4.0 to 10.0 are also useful. For example: silver salts of organic acids (eg, gallic, oxalic, behenic, stearic, palmitic, lauric, oleic, caproic, myristic, palmitic, maleic, linoleic) Carboxyalkylthiourea salt of silver (eg, 1- (3-carboxypropyl) thiourea,
1- (3-carboxypropyl) -3,3-dimethylthiourea); a silver complex of a polymer reaction product of an aldehyde and a hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.); Hydroxy-substituted acids (e.g., salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,
5-thiodisalicylic acid), silver salts or complexes of thioenes (for example, 3- (2-carboxyethyl) -4-hydroxymethyl-4- (thiazoline-2-thioene, and 3
-Carboxymethyl-4-thiazoline-2-thioene), imidazole, pyrazole, urazole, 1,
Complexes or salts of silver with a nitrogen acid selected from 2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole; saccharin, 5-chlorosalicylaldoxime And silver salts of mercaptides. Examples of suitable silver salts are described in Research Disclosure Nos. 17029 and 2996.
3, particularly preferred silver sources are silver behenate,
Silver arachidate and / or silver stearate.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, and can be obtained by a forward mixing method, a reverse mixing method, a simultaneous mixing method, and a method described in JP-A-9-12764.
A controlled double jet method as described in No. 3 is preferably used.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, but a needle crystal having a short axis and a long axis is preferable. As is well known in photosensitive silver halide photosensitive materials, the inverse relationship between the size of silver salt crystal grains and their covering power also holds in the photothermographic material of the present invention. When the size of the hundred silver salt particles as the image forming portion is large, it means that the covering power is small and the image density is low. Therefore, it is necessary to reduce the size of the organic silver salt. In the present invention, the short axis 0.
It is preferably from 0.01 μm to 0.20 μm, from 0.10 μm to 5.0 μm on the long axis, and from 0.01 μm to 0.1 μm on the short axis.
More preferably, it is 15 μm or less, and the major axis is 0.10 μm or more and 4.0 μm or less.

The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion means the percentage of the value obtained by dividing the standard deviation of the lengths of the minor axis and major axis by the minor axis and major axis, respectively, is preferably 100% or less, more preferably 80% or less, and even more preferably 50% or less. Is good. The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring the monodispersity, there is a method of obtaining the standard deviation of the volume-weighted average diameter of the organic silver salt, and the percentage (coefficient of variation) divided by the volume-weighted average diameter is preferably 100% or less, more preferably It is preferably at most 80%, more preferably at most 50%.
As a measuring method, for example, an organic silver salt dispersed in a liquid is irradiated with a laser beam, and the autocorrelation coefficient with respect to the time change of the fluctuation of the scattered light is obtained from the particle size (volume weight average diameter) obtained. be able to.

[0108] The coating amount of the organic silver salt, in particular an organic acid silver in the photosensitive material of the present invention preferably light-sensitive material 1 m ² per 0.5~5.0g as the amount of silver, further 1.0 to 3.0
g is more preferred.

Examples of suitable reducing agents for the photothermographic material of the present invention are described in US Pat. Nos. 3,770,448 and 3,77.
3,512, 3,593,863, and Resear
ch Disclosure Nos. 17029 and 29963.

Aminohydroxycycloalkenones (eg, 2-hydroxypiperidino-2-cyclohexenone); aminoreductones esters (eg, piperidinohexose reductone monoacetate) as precursors of reducing agents An N-hydroxyurea derivative (for example, Np-methylphenyl-N
Hydrazones of aldehydes or ketones (e.g. anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (e.g.
Hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (eg, benzenesulfhydroxamic acid); sulfonamidoanilines (eg, 4- (N- Methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone); tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydro) Aminooxins; Azines (eg, a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid); a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine; Hydroxanoic acids Combinations of azines and sulfonamidophenols; α-cyanophenylacetic acid derivatives; combinations of bis-β-naphthol and 1,3-dihydroxybenzene derivatives; 5-pyrazolones; sulfonamidophenol reducing agents; 2-phenylindane-1 ,
3-dione and the like; chroman; 1,4-dihydropyridines (eg, 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine); bisphenols (eg, bis (2-hydroxy-3- t-butyl-5
-Methylphenyl) methane, bis (6-hydroxy-m
-Tri) mesitol, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
4,5-ethylidene-bis (2-t-butyl-6-methyl) phenol), ultraviolet-sensitive ascorbic acid derivatives and 3-pyrazolidones. Among them, particularly preferred reducing agents are hindered phenols. Examples of the hindered phenols include compounds represented by the following general formula (A).

[0111]

Embedded image

In the formula, R represents a hydrogen atom or a group having 1 to 1 carbon atoms.
10 alkyl group (e.g., -C ₄ H _9, 2,4,4- trimethylpentyl) represents, R 'and R "are C 1 -C
To 5 alkyl groups (for example, methyl, ethyl, t-butyl).

Specific examples of the compound represented by formula (A) are shown below. However, the present invention is not limited to the following compounds.

[0114]

Embedded image

[0115]

Embedded image

The amount of the reducing agent including the compound represented by the formula (A) is preferably 1 × per mole of silver.
10 ⁻² to 10 mol, particularly preferably 1 × 10 ⁻² to
1.5 mol.

Binders suitable for the photothermographic material of the present invention are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, (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 (vinylacetal) s (eg, poly (vinylformal) and poly (vinylbutyral)), poly (ester) Kind, poly ( Urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxides),
Poly (carbonate) s, poly (vinyl acetate),
There are cellulose esters and poly (amides). It may be hydrophilic or non-hydrophilic.

In the present invention, the amount of the binder in the photosensitive layer is 1.5 to 10 for the purpose of preventing dimensional fluctuation after thermal development.
g / m ² . More preferably, 1.
7 to 8 g / m ² . If it is less than 1.5 g / m ² , the density of the unexposed portion will increase significantly, and may not be usable.

In the present invention, a matting agent is preferably contained on the photosensitive layer side, and in order to prevent damage to the image after thermal development, it is preferable to provide a matting agent on the surface of the photosensitive material. The matting agent is preferably contained in a weight ratio of 0.5 to 10% with respect to all binders on the emulsion layer side.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as inorganic substances, silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, etc., and alkali described in British Patent No. 1,173,181 etc. An earth metal or a carbonate such as cadmium or zinc can be used as a matting agent. As organic matter,
Starch described in U.S. Pat. No. 2,322,037, Belgian Patent No. 625,451 and British Patent No. 981,19
No. 8 and the like, and starch derivatives described in JP-B-44-3643.
No. 33, Swiss Patent No. 33
No. 0,158, polystyrene or polymethacrylate; U.S. Pat. No. 3,079,257; polyacrylonitrile; U.S. Pat. No. 3,022,16.
An organic matting agent such as polycarbonate described in No. 9 or the like can be used.

The shape of the matting agent may be either regular or irregular, but it is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.

The matting agent used in the present invention preferably has an average particle size of 0.5 μm to 10 μm, more preferably 1.0 μm to 8.0 μm. The matting agent has a coefficient of variation of the particle size distribution of 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 matting agent according to the present invention can be contained in any constituent layer, but in order to achieve the object of the present invention, it is preferably a constituent layer other than the photosensitive layer, and more preferably from the support. The outermost layer to look at.

The method of adding the matting agent according to the present invention may be a method of dispersing in a coating solution in advance and applying the solution.
A method of spraying a matting agent after the application liquid is applied and before the drying is completed may be used. When a plurality of types of matting agents are added, both methods may be used in combination.

The processing method and the image forming method using the photothermographic material of the present invention form a photographic image by the photothermographic processing. The photothermographic material of the present invention is stable at room temperature. Thereafter, development is performed by heating to a high temperature (for example, 80 ° C. to 140 ° C.).

By heating, silver is produced through an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is accelerated by the catalytic action of the latent image generated on the silver halide upon exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image. This reaction process proceeds without supplying a processing liquid such as water from the outside.

The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. A filter layer may be formed on the same side as or opposite to the photosensitive layer to control the amount or wavelength distribution of light passing through the photosensitive layer, or the photosensitive layer may contain a dye or pigment. . As the dye, a compound described in Japanese Patent Application No. 7-11184 is preferred.
The photosensitive layer may be composed of a plurality of layers, and the sensitivity may be changed to a high-sensitive layer / low-sensitive layer or a low-sensitive layer / high-sensitive layer for adjusting the gradation. Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other forming layers.

The photothermographic material of the present invention may contain, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, and a coating aid.

The photothermographic material of the present invention preferably contains a toning agent. Toning agents are disclosed in US Pat.
No. 254, No. 3847612 and No. 41232
No. 82, it is a material well known in the photographic art. Examples of suitable toning agents are Research Disclosure No. 1
No. 7029, which includes:

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, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3
-Mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (for example,
N- (dimethylaminomethyl) phthalimide); blocked pyrazoles, isothiuron
) derivatives and certain photobleaching agents (eg, N, N'-hexamethylene (1-carbamoyl-
3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate), and 2- (tribromomethylsulfonyl) benzothiazole combinations); merocyanine dyes (e.g., , 3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolinylidene))-
1-methylethylidene) -2-thio-2,4-oxazolidinedione); phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7 −
Dimethyloxyphthalazinone and 2,3-dihydro-
1,4-phthalazinedione); 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 Phthalazine (including adducts of phthalazine) 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- A combination with at least one compound selected from nitrophthalic acid and tetrachlorophthalic anhydride; quinazolinediones, benzoxazine, naloxazine derivatives; benzoxazine-2,4
-Diones (for example, 1,3-benzoxazine-2,
4-dione); pyrimidines and asymmetric-triazines (eg, 2,4-dihydroxypyrimidine), and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2) , 3a,
5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained in order to suppress or accelerate the development to control the development, to improve the spectral sensitization efficiency, and to improve the storage stability before and after the development. be able to. When a mercapto compound is used in the present invention, it may have any structure,
Those represented by SS-Ar are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or a 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, benzoterzole, imidazole, oxazole,
Pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazolinone. This heteroaromatic ring is, for example, a halogen (for example,
Br and Cl), hydroxy, amino, carboxy,
Alkyl (eg one or more carbon atoms, preferably 1
May have a substituent selected from the group consisting of those having from 1 to 4 carbon atoms) and alkoxy (e.g., having at least one carbon atom, preferably having from 1 to 4 carbon atoms). Good mercapto-substituted heteroaromatic compounds include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzimidazole, 6-ethoxy-2-mercaptobenzothiazole,
2,2'-dithiobisbenzothiazole, 3-mercapto-1,2,4-triazole, 4,5-diphenyl-
2-imidazole thiol, 2-mercaptoimidazole, 1-ethyl-2-mercaptobenzimidazole,
2-mercaptoquinoline, 8-mercaptopurine, 2-mercaptopurine
Mercapto-4- (3H) quinazolinone, 7-trifluoromethyl-4-quinolinethiol, 2,3,5,6-
Tetrachloro-4-pyridinethiol, 4-amino-6
-Hydroxy-2-mercaptopyrimidine monohydrate, 2-amino-5-mercapto-1,3,4-thiadiazole, 3-amino-5-mercapto-1,2,4-
Triazole, 4-hydroxy-2-mercaptopyrimidine, 21-mercaptopyrimidine, 4,6-diamino-
2-mercaptopyrimidine, 2-mercapto-4-methylpyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,4-triazole, 2-mercapto-4
-Phenyloxazole and the like, but the present invention is not limited to these. The addition amount of these mercapto compounds is 0.001 to 1 mol per silver in the emulsion layer.
A range of 1.0 mole is preferred, more preferably 0.01 to 0.3 mole per mole of silver.

What is known as the most effective antifoggant is mercury ion. The use of a mercury compound as an antifoggant in a light-sensitive material is disclosed in, for example, US Pat. No. 3,589,903. However, mercury compounds are environmentally unfriendly. Examples of the non-mercury antifoggant include U.S. Pat. Nos. 4,546,075 and 4,452,885 and JP-A-59-572.
No. 34 is preferred.

Preferred non-mercury antifoggants are compounds such as those disclosed in US Pat. Nos. 3,874,946 and 4,756,999, —C (X ₁ ) (X ₂ )
(X ₃ ) (where X ₁ and X ₂ are halogen and X ₃ is hydrogen or halogen) and is a heterocyclic compound having one or more substituents. Examples of suitable antifoggants include paragraphs [0062] to JP-A-9-90550.
The compounds described in [0063] are preferably used.

Further, more suitable antifoggants are disclosed in US Pat. No. 5,028,523 and British Patent Application No. 92221.
No. 383.4, No. 9300147.7, No. 931
No. 1790.1.

The most effective antifoggant is represented by the following general formula 1:
These compounds are represented by

[0137]

Embedded image

[Wherein X ₁ and X ₂ represent a halogen atom. Y represents a divalent linking group. A represents a hydrogen atom, a halogen atom or another electron-withdrawing group. m represents an integer of 3 or more and 4 or less. Q represents a heterocyclic group, an aryl group or an aliphatic group. n represents an integer of 0 or more and 3 or less. When Q is an aliphatic group, the number of halogen atoms in the whole molecule is 6 or more and less than 10. ]

[0139]

Embedded image

[Wherein X ₁ and X ₂ represent a halogen atom. A represents a hydrogen atom, a halogen atom or another electron-withdrawing group. Q represents an aromatic hetero 5-membered ring, a furan ring, a thiophene ring or a pyrrole ring having one oxygen atom and two or more and three or less nitrogen atoms. However, when Q is a thiophene ring, X ₁ represents a bromine atom. ]

[0141]

Embedded image

[Wherein X ₁ and X ₂ represent a halogen atom. A represents a hydrogen atom, a halogen atom or another electron-withdrawing group.

Y is -SO-, -CO-, -N (R ₁₁ ) -SO _2- , -N (R ₁₁ )-
CO-, -N (R ₁₁ ) -COO-, -COCO-, -COO-, -OCO-, -OCOO-, -SCO-, -SCOO-, -C (Z ₁ )
(Z ₂ )-, an alkylene, an arylene, a divalent heterocyclic ring, or a divalent linking group formed by any combination thereof. R ₁₁ represents a hydrogen atom or an alkyl group. Z ₁ and Z ₂ represent a hydrogen atom or an electron-withdrawing group. Z ₁ and Z ₂ are not hydrogen atoms at the same time. Q represents an aliphatic group, an aromatic group or a heterocyclic group. However, Y is -SO
In the case of-, Q represents an aromatic hetero 5-membered ring group having at least one hetero atom other than N and a pyridine ring group. ]

First, the compound represented by Formula 1 will be described in detail.

The halogen atom represented by X ₁ and X ₂ is
A fluorine atom, a chlorine atom, a bromine atom and an iodine atom which may be the same or different from each other, preferably a chlorine atom, a bromine atom and an iodine atom, more preferably a chlorine atom and a bromine atom, particularly preferably bromine Is an atom.

Y represents a divalent linking group, specifically, -SO _2- , -SO-, -CO-, -N (R ₁₁ ) -SO _2- , -N (R ₁₁ ) -CO _{-, -N (R 11) -COO-} , -COCO-, -COO-, -OCO-, -OCOO-, -SCO-, -SCOO-, -C (Z 1) (Z 2) -, alkylene, Represents a divalent linking group formed by arylene, a divalent heterocyclic ring, or any combination thereof.

Preferred as Y is -SO _2- , -SO-, -CO-
And more preferably —SO ₂ —.

N is preferably 1.

R ₁₁ represents a hydrogen atom or an alkyl group, preferably a hydrogen atom.

Z ₁ and Z ₂ represent a hydrogen atom or an electron-withdrawing group, but Z ₁ and Z ₂ are not hydrogen atoms at the same time.

Preferred as the electron-withdrawing group are those having a Hammett's substituent constant σp value of 0.01 or more;
More preferably, the substituent is 0.1 or more.

Regarding Hammett's substituent constant, see Journa
l of Medicinal Chemistry, 1973, Vol.16, No.11,1207-12
16 mag can be referred to.

Examples of the electron-withdrawing group include a halogen atom (fluorine atom (σp value: 0.06), a chlorine atom (σ
p value: 0.23), bromine atom (σp value: 0.23), iodine atom (σp value: 0.18), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl ( σp value: 0.33), trifluoromethyl (σ
p value: 0.54)), a cyano group (σp value: 0.66),
Nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (eg, methanesulfonyl (σp value: 0.72)), aliphatic / aryl or heterocyclic acyl group (eg, acetyl (σp value) Value: 0.5
0), benzoyl (σp value: 0.43)), ethynyl group (σp value: 0.09), aliphatic / aryl or heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp value: 0.45), phenoxy) Carbonyl (σp
Value: 0.45)), carbamoyl group (σp value: 0.3
6) and a sulfamoyl group (σp value: 0.57).

Preferred as Z ₁ and Z ₂ are a halogen atom, a cyano group and a nitro group, and among the halogen atoms, preferred are a chlorine atom, a bromine atom and an iodine atom, and more preferred are a chlorine atom, A bromine atom is particularly preferred.

A represents a hydrogen atom, a halogen atom or another electron-withdrawing group. The electron-withdrawing group represented by A is preferably a compound having a Hammett's substituent constant σp value of 0.01.
The above substituents are more preferable, and the σp value is more preferably 0.1.
These are the above substituents.

Examples of the electron-withdrawing group include a halogen atom (fluorine atom (σp value: 0.06), a chlorine atom (σp value
Value: 0.23), bromine atom (σp value: 0.23), iodine atom (σp value: 0.18), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value) Value: 0.33), trifluoromethyl (σp
Value: 0.54)), cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σ
p value: 0.72)), aliphatic / aryl or heterocyclic acyl group (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), ethynyl group (σp
Value: 0.09), an aliphatic / aryl or heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp
Value: 0.45), phenoxycarbonyl (σp value: 0.
45)), a carbamoyl group (σp value: 0.36), a sulfamoyl group (σp value: 0.57), and the like.

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

Q represents an aliphatic group, an aromatic group or a heterocyclic group, and the aliphatic group represented by Q is a linear, branched or cyclic alkyl group (preferably having 1 to 30 carbon atoms; Preferred are those having 1 to 20 carbon atoms, and more preferred are those having 1 to carbon atoms.
12, for example, methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, cyclopropyl, cyclopentyl, cyclohexyl and the like. ), Alkenyl group (preferably having 2 to 2 carbon atoms)
30, more preferably 2 to 20 carbon atoms, still more preferably 2 to 12 carbon atoms, for example, vinyl, allyl,
-Butenyl, 3-pentenyl and the like. ), An alkynyl group (preferably having 2 to 30 carbon atoms, more preferably having 2 to 20 carbon atoms, and still more preferably having 2 to 12 carbon atoms).
And for example, propargyl, 3-pentenyl and the like. ), And may have a substituent. Examples of the substituent include a carboxy group, an acyl group, an acylamino group, a sulfonylamino group, a carbamoyl group, a sulfamoyl group, an oxycarbonylamino group, and a ureido group. Preferred as the aliphatic group represented by Q is an alkyl group, and more preferred is a chain alkyl group.

The aromatic group represented by Q is preferably a monocyclic or bicyclic aryl group having 6 to 30 carbon atoms (eg, phenyl, naphthyl, etc.), and more preferably 6 to 20 carbon atoms. Phenyl group, more preferably 6-1
2 is a phenyl group. The aryl group may have a substituent, and examples of the substituent include a carboxy group, an acyl group, an acylamino group, a sulfonylamino group, a carbamoyl group, a sulfamoyl group, an oxycarbonylamino group, and a ureido group.

The heterocyclic group represented by Q is N, O or S
A 3- to 10-membered saturated or unsaturated heterocyclic ring containing at least one atom, which may be a single ring or may form a condensed ring with another ring. The heterocyclic group is preferably a 5- or 6-membered aromatic heterocyclic group, more preferably a 5- or 6-membered aromatic heterocyclic group containing a nitrogen atom, and even more preferably a nitrogen-containing 1-membered aromatic heterocyclic group. 5 to 6-membered aromatic heterocyclic group containing 1 to 2 atoms.

Specific examples of the heterocycle include, for example, pyrrolidine, piperidine, piperazine, morpholine, 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, indolenine, more preferably triazine, quinoline, thiadiazole, benzthiazole, oxadiazole, particularly preferred Is pyridine,
Quinoline, thiadiazole and oxadiazole.
Preferred as Q is an aromatic nitrogen-containing heterocyclic group.

M represents an integer of 3 or more and 4 or less, and preferably m is 3.

When Q is an aliphatic group, the number of halogen atoms in the whole molecule is 6 or more and less than 10, preferably 6 or less.
It is.

Next, the compound represented by Formula 2 will be described in detail.

In the formula, X ₁ , X ₂ and A have the same meanings as those described in formula 1.

Q represents an aromatic hetero 5-membered ring having one oxygen atom and two or more and three or less nitrogen atoms, a furan ring, a thiophene ring and a pyrrole ring, wherein one oxygen atom and two nitrogen atoms Specific examples of the aromatic hetero 5-membered ring having one or more and three or less include oxadiazole and oxatriazole, and oxadiazole is preferable.

Preferred among the rings represented by Q is oxadiazole.

Next, the compound represented by Formula 3 will be described in detail.

In the formula, X ₁ , X ₂ and A have the same meanings as those described in formula 1.

Y is -SO-, -CO-, -N (R ₁₁ ) -SO _2- , -N (R ₁₁ )-
_{CO-, -N (R 11) -COO-} , -COCO-, -COO-, -OCO-, -OCOO-, -SCO-, -SCOO-, -C
(Z ₁ ) (Z ₂ )-, an alkylene, an arylene, a divalent heterocyclic ring or a divalent linking group formed of any combination thereof. R
₁₁ represents a hydrogen atom or an alkyl group, preferably a hydrogen atom. Z ₁ and Z ₂ represent a hydrogen atom or an electron-withdrawing group, but Z ₁ and Z ₂ are not hydrogen atoms at the same time.

Preferred as the electron-withdrawing group are those having a Hammett's substituent constant σp value of 0.01 or more;
More preferred are substituents of 0.1 or more. For the Hammett's substituent constant, see Journal of Medicinal Chemi.
stry, 1973, Vol. 16, No. 11, 1207-1216, etc. can be referred to.

Examples of the electron-withdrawing group include a halogen atom (a fluorine atom (σp value: 0.06) and a chlorine atom (σp
Value: 0.23), bromine atom (σp value: 0.23), iodine atom (σp value: 0.18), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value) Value: 0.33), trifluoromethyl (σp
Value: 0.54)), cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σ
p value: 0.72)), aliphatic / aryl or heterocyclic acyl group (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), ethynyl group (σp
Value: 0.09), an aliphatic / aryl or heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp
Value: 0.45), phenoxycarbonyl (σp value: 0.
45)), a carbamoyl group (σp value: 0.36), a sulfamoyl group (σp value: 0.57), and the like.

Preferred as Z ₁ and Z ₂ are a halogen atom, a cyano group and a nitro group. Among the halogen atoms, preferred are a chlorine atom, a bromine atom and an iodine atom, and more preferred are a chlorine atom and a bromine atom,
Particularly preferred is a bromine atom.

Preferred as Y is -SO-, -CO-, -N (R
₁₁ ) -SO _2- , -N (R ₁₁ ) -CO-, -C (Z ₁ ) (Z ₂ )-, more preferably-
_{SO -, - C (Z 1} ) (Z 2) - a.

N is preferably 1.

Q represents an aliphatic group, an aromatic group, or a heterocyclic group. However, when Y is -SO-, Q represents a 5-membered aromatic heterocyclic group having at least one heteroatom other than N and a pyridine ring. These rings may be further condensed with other rings.

Specific examples of the aromatic 5-membered heterocyclic group having at least one hetero atom other than N include thiazole, oxazole, thiophene, furan, pyrrole, thiadiazole, oxadiazole, thiatriazole,
Oxatriazole is mentioned, and Q is preferably a thiadiazole ring, a pyridine ring or a quinoline ring.

The specific examples of the compounds represented by the general formulas 1, 2 and 3 are shown below, but the present invention is not limited thereto.

[0179]

Embedded image

[0180]

Embedded image

[0181]

Embedded image

[0182]

Embedded image

[0183]

Embedded image

The compounds represented by formulas 1 to 3 are described, for example, in JP-A-54-165, JP-A-6-340611, JP-A-7-27881, JP-A-7-5621, and JP-B-7-119.
No. 953, U.S. Pat.
No. 14, 5460938, 5464737, and European Patent Nos. 605981 and 631176.

Specific examples of the synthesis of the compounds represented by formulas 1 to 3 are shown below. (Synthesis Example 1) Synthesis of Exemplified Compound 1-1 2,4,6-tris-carboxymethylthio-1,3,2
Synthesis of 4-triazine 2,4,6-trimercapto-
23.0 g (0.13 mol) of 1,3,4-triazine,
While stirring 54.0 g (0.44 mol) of chloroacetic acid and 300 ml of ethanol at room temperature, an aqueous solution of 17.66 g (0.44 mol) of sodium hydroxide / 30 ml of water was added dropwise. After stirring for 20 minutes, the mixture was heated to 50 ° C., and further 17.6 g (0.44 mol) of sodium hydroxide / water 3
0 ml of the aqueous solution was slowly added dropwise. After stirring at 50 ° C. for 3 hours, the mixture was cooled to room temperature, water was added until the reaction solution became homogeneous, and hydrochloric acid was further added to neutralize the mixture. The obtained crystals were collected by filtration and recrystallized with methanol to give 2,4,6-
35.4 g (0.10 mol) of tris-carboxymethylthio-1,3,4-triazine was obtained. 76% yield

Synthesis of 2,4,6-tris-tribromosulfonyl-triazine (Exemplified Compound 1-1) 49.1 g (1.23 mol) of sodium hydroxide / 1 liter of water was stirred at 0 to 5 ° C. Where bromine 31.
One milliliter was slowly dropped. Further, the 2,4,6-tris-carboxymethylthio-
8.2 g (0.023 mol) of 1,3,4-triazine,
An aqueous solution of 7.2 g (0.0857 mol) of sodium hydrogen carbonate and 150 ml of water was slowly added dropwise so that the internal temperature did not exceed 10 ° C. After completion of the dropwise addition, the temperature was raised to room temperature and left overnight. The precipitated solid was collected by filtration, washed with water, and recrystallized from ethanol to give Exemplified Compound 1 as a white solid.
-1 (11.3 g, 0.011 mol) was obtained. 48% yield

(Synthesis Example 2) Synthesis of Exemplified Compound 2-7 Synthesis of 2-carboxymethylthiofuran 20.0 g (0.20 mol) of 2-mercaptofuran, 27.0 g (0.22 mol) of chloroacetic acid and ethanol 3
While stirring 00 ml at room temperature, an aqueous solution of 8.8 g (0.22 mol) of sodium hydroxide / 15 ml of water was added dropwise. After stirring for 20 minutes, the mixture was heated to 50 ° C., and an aqueous solution of 8.8 g (0.22 mol) of sodium hydroxide / 15 ml of water was slowly added dropwise. After stirring at 50 ° C. for 3 hours,
After cooling to room temperature, water was added until the reaction solution became homogeneous, and hydrochloric acid was further added to neutralize it.

The obtained crystals were collected by filtration and recrystallized from methanol to obtain 23.5 g (0.148 mol) of 2-carboxymethylthiofuran. 74% yield

Synthesis of 2-tribromomethylsulfonylfuran (Exemplified Compound 2-7) Sodium hydroxide 49.1
g (1.23 mol) / water (1 liter) was slowly added dropwise with stirring at 0 to 5 ° C. while bromine (31.1 ml) was added dropwise. Further, 11.2 g (0.0706 mol) of 2-carboxymethylthiofuran obtained in the above reaction, 7.2 g (0.0857 mol) of sodium hydrogen carbonate and water 1
An aqueous solution of 50 ml was slowly added dropwise so that the internal temperature did not exceed 10 ° C. After completion of the dropwise addition, the temperature was raised to room temperature and left overnight.

The precipitated solid was collected by filtration, washed with water, and recrystallized from ethanol to give Exemplified Compound 2 as a white solid.
As a result, 11.5 g (0.0312 mol) of -7 was obtained. Yield 44
%

(Synthesis Example 3) Synthesis of Exemplified Compound 3-1 2-carboxymethylthio-5-methyl-1,3,4-
Synthesis of thiadiazole 2-mercapto-5-methyl-
While stirring 26.4 g (0.20 mol) of 1,3,4-thiadiazole, 27.0 g (0.22 mol) of chloroacetic acid and 300 ml of ethanol at room temperature, 8.8 g of sodium hydroxide (0. (22 mol) / water (15 ml) was added dropwise. After stirring for 20 minutes, the mixture was heated to 50 ° C., and further 8.8 g (0.22 mol) of sodium hydroxide / water 15
ml of the aqueous solution was slowly added dropwise. After stirring at 50 ° C. for 3 hours, the mixture was cooled to room temperature, water was added until the reaction solution became homogeneous, and hydrochloric acid was further added to neutralize the mixture.

The obtained crystals were collected by filtration and recrystallized from methanol to give 28.7 g of 2-carboxymethylthio-5-methyl-1,3,4-thiadiazole (0.2%).
150 mol). 75% yield

Synthesis of 2-tribromomethylsulfo-5-methyl-1,3,4-thiadiazole (Exemplified Compound 3-1) 49.1 g (1.23 mol) of sodium hydroxide in 1 liter of water While stirring at 30 ° C .;
One milliliter was slowly dropped. Furthermore, 2-carboxymethylthio-5-methyl-1, obtained by the above reaction,
An aqueous solution of 13.5 g (0.0706 mol) of 3,4-thiadiazole, 7.2 g (0.0857 mol) of sodium bicarbonate and 150 ml of water was slowly added dropwise so that the internal temperature did not exceed 5 ° C. After completion of the dropwise addition, the temperature was raised to room temperature and left overnight.

The precipitated solid was collected by filtration, washed with water, and recrystallized from ethanol to give Exemplified Compound 3 as a white solid.
-1 (13.2 g, 0.0332 mol) was obtained. Yield 47
%

The amount of the compounds represented by the general formulas 1 to 3 is not particularly limited, but is preferably in the range of 10 ^-4 mol to 1 mol / Ag mol, and particularly preferably in the range of 10 ^-3 mol to 0.3 mol / Ag mol.
The Ag mole range is more preferred.

The locations where the compounds represented by the general formulas 1 to 3 can be added can be changed depending on the layer constitution of the light-sensitive material, and various embodiments will be described below.

As a typical embodiment, in a photothermographic material having at least one photosensitive layer and a layer adjacent to the photosensitive layer on a support, photosensitive silver halide,
An embodiment containing an organic silver salt and a binder, and further containing at least one compound represented by the general formulas 1 to 3, wherein the photosensitive layer contains a photosensitive silver halide, an organic silver salt and a binder, and the adjacent layer contains An embodiment containing at least one compound represented by the general formulas 1 to 3, the photosensitive layer contains a photosensitive silver halide and a binder, and further contains at least one compound represented by the general formulas 1 to 3. An embodiment in which an adjacent layer contains an organic silver salt, the photosensitive layer contains a photosensitive silver halide and a binder, the adjacent layer contains an organic silver salt, and at least one of the compounds represented by formulas 1 to 3 Embodiments containing species are included. Preferred in the present invention is
It is an aspect of.

The method of adding the compounds represented by the general formulas 1 to 3 is not limited. For example, it is preferable to add the compounds by dissolving them in an organic solvent.

In the photosensitive layer according to the invention, a polyhydric alcohol (for example, US Pat.
Glycerin and diols of the type described in U.S. Pat. No. 960404), U.S. Pat.
Fatty acids or esters described in No. 21060, silicone resins described in British Patent No. 955061 and the like can be used.

A hardening agent may be used for each layer such as the photosensitive layer, the protective layer and the back layer of the present invention. Examples of hardeners include:
Isocyanate compounds, epoxy compounds described in U.S. Pat. No. 4,791,042, etc .;
For example, vinylsulfone-based compounds described in JP-A-89048 and the like are used.

In the present invention, a surfactant may be used for the purpose of improving coating properties and charging. As an example of the surfactant, any of anionic, cationic, betaine, nonionic, and fluorine-based surfactants can be appropriately used. Specifically, Japanese Patent Application Laid-Open No. Sho 62-170950, U.S. Pat.
No. 82504, etc., a fluoropolymer surfactant,
JP-A-60-244945, JP-A-63-18813
No. 5, fluorinated surfactants described in US Pat.
85965 and the like; polyalkylene oxides and anionic surfactants described in JP-A-6-301140 and the like.

The photographic emulsion for thermal development in the present invention employs various coating methods including a dip coating method, an air knife coating method, a flow coating method, and an extrusion coating method using a hopper of the type described in US Pat. No. 2,681,294. be able to. If desired, two or more layers can be applied simultaneously by the methods described in U.S. Pat. No. 2,761,791 and British Patent No. 8,370,955.

The support used in the present invention may be a plastic film (for example, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate) in order to obtain a predetermined optical density after development and to prevent image deformation after development. , Polyethylene naphthalate).

Among them, preferred supports include plastics (hereinafter abbreviated as SPS) containing polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene naphthalate (hereinafter abbreviated as PEN), and a styrene polymer having a syndiotactic structure. Support.
The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

A plastic support which has been heat-treated can also be used. The plastics to be employed include the above-mentioned plastics. The heat treatment of the support means that after forming these supports and before the photosensitive layer is applied, at a temperature higher than the glass transition point of the support by 30 ° C. or more,
Preferably at a temperature higher than 35 ° C., more preferably 40 ° C.
It is preferable to heat at a temperature higher than ℃. However, the effect of the present invention cannot be obtained by heating at a temperature exceeding the melting point of the support.

Next, the plastic used will be described.

In PET, all the polyester components are made of polyethylene terephthalate. In addition to polyethylene terephthalate, terephthalic acid, naphthalene-2,6-dicarboxylic acid, isophthalic acid, butylene dicarboxylic acid, and 5-sodium sulfo acid are used as acid components. A polyester containing a modified polyester component of isophthalic acid, adipic acid or the like and a glycol component such as ethylene glycol, propylene glycol, butanediol, cyclohexanedimethanol or the like in an amount of 10 mol% or less of the entire polyester may be used.

Examples of PEN include polyethylene 2, 6 naphthalate, copolymerized polyester comprising terephthalic acid, 2-6 naphthalenedicarboxylic acid and ethylene glycol, and polyesters comprising a mixture of two or more of these polyesters as main constituents. Is preferred. Also,
Further, another copolymer component may be copolymerized, or another polyester may be mixed.

SPS is polystyrene having steric regularity unlike ordinary polystyrene (atactic polystyrene). The regular stereoregular structure part of SPS is called a racemo chain, and it is preferable that there are more regular parts such as two, three, five or more. In the present invention, the racemo chain is 2 It is preferably 85% or more in the chain, 75% or more in the three chains, 50% or more in the five chains, and 30% or more in the further chains. The polymerization of SPS can be carried out according to the method described in JP-A-3-131843.

The method for forming a film of a support and the method for producing an undercoat according to the present invention may be a known method. Preferably, the method is described in paragraphs [0030] to [0] of JP-A-9-50094.
070].

[0211]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited by these examples.

Example 1 [Preparation of Subbed Photographic Support] <Preparation of PET Subbed Photographic Support> A commercially available biaxially stretched heat-fixed PET film having a thickness of 175 μm and 8 w / m on both sides. Apply a corona discharge treatment for ² minutes, apply the following undercoating coating solution a-1 on one surface so as to have a dry film thickness of 0.8 μm, and dry to form an undercoating layer A-1. Was coated with the following undercoating coating solution b-1 so as to have a dry film thickness of 0.8 μm and dried to obtain an undercoating layer B-1.

<< Undercoat Coating Solution a-1 >> Butyl acrylate (30% by weight) t-butyl acrylate (20% by weight) Styrene (25% by weight) 2-hydroxyethyl acrylate (25% by weight) copolymer latex liquid (Solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finished to 1 liter with water.

<< Undercoat Coating Solution b-1 >> Copolymer latex liquid of butyl acrylate (40% by weight) styrene (20% by weight) glycidyl acrylate (40% by weight) (solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Make up to 1 liter with water.

Subsequently, the undercoat layer A-1 and the undercoat layer B-1
A corona discharge of 8 w / m ² · min is applied to the upper surface of the lower layer, and the lower layer upper layer coating solution a-2 described below is coated on the lower layer A-1 so as to have a dry film thickness of 0.1 μm. Sublayer B as Layer A-2
-1 is coated with the following undercoating layer coating solution b-2 having a dry film thickness of 0.
Coating was performed as a subbing upper layer B-2 having an antistatic function so as to have a thickness of 8 μm.

<< Coating solution a-2 for lower undercoat >> Weight of gelatin 0.4 g / m ² (C-1) 0.2 g (C-2) 0.2 g (C-3) 0.1 g Silica particles ( (Average particle size: 3 μm) 0.1 g Finish with water to 1 lot.

<< Lower Coating Upper Layer Coating Solution b-2 >> (C-4) 60 g Latex liquid containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 0.5 g (C-6) 12 g Polyethylene glycol ( (Weight average molecular weight: 600) 6 g Finished to 1 liter with water.

[0218]

Embedded image

[0219]

Embedded image

(Preparation of Photosensitive Silver Halide Emulsion 1) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 333 ml of an aqueous solution containing 66.6 g of silver nitrate and (99.89 / 0.11) An aqueous solution containing potassium bromide and potassium iodide in a molar ratio was added over 9 minutes by a controlled double jet method while maintaining the pAg at 7.7. Thereafter, 37 ml of an aqueous solution containing 7.4 g of silver nitrate, an aqueous solution containing potassium bromide, and 1 × 10 ⁻⁴ mol of iridium chloride per mol of silver were added over 1 minute by a controlled double jet method while maintaining a pAg of 7.7. . Thereafter, 4-hydroxy-6-methyl-1,3,3
a, 7-Tetrazindene 0.3 g was added, and the pH was adjusted to 5 with NaOH to obtain a cubic iodobromide having an average grain size of 0.06 μm, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87%. Silver particles were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain photosensitive silver halide emulsion 1. The average silver iodide content of the silver halide grains contained in Emulsion 1 was 0.1 mol%, and the silver iodide content on the grain surface was 0.0 mol%.

(Preparation of Photosensitive Silver Halide Emulsion 2) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and (9)
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 9.9 / 0.1) and iridium chloride were added in an amount of 1: 1 per mole of silver.
× 10 ^-4 mol was added over 10 minutes by a controlled double jet method while keeping the pAg at 7.7. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-
Add 0.3 g of tetrazaindene and adjust the pH to 5 with NaOH.
To obtain cubic silver iodobromide grains having an average grain size of 0.06 μm, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87%. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain photosensitive silver halide emulsion 2. The average silver iodide content of the silver halide grains contained in Emulsion 2 was 0.1 mol%, and the average value of the silver iodide content on the grain surface was 0.1 mol%.

(Preparation of Photosensitive Silver Halide Emulsion 3) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 333 ml of an aqueous solution containing 66.6 g of silver nitrate and (99.91 / 0.09) An aqueous solution containing potassium bromide and potassium iodide in a molar ratio was added over 9 minutes by a controlled double jet method while maintaining the pAg at 7.7. Thereafter, 37 ml of an aqueous solution containing 7.4 g of silver nitrate and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 9.8 / 0.2) and iridium chloride are added in an amount of 1 / mol silver.
× 10 ^-4 mol was added over 1 minute by a controlled double jet method while keeping the pAg at 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%. Thus, cubic silver iodobromide grains having a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain photosensitive silver halide emulsion 3. The average silver iodide content of the silver halide grains contained in Emulsion 3 was 0.1 mol%, and the silver iodide content on the grain surface was 0.2 mol%.

(Preparation of Photosensitive Silver Halide Emulsion 4) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 333 ml of an aqueous solution containing 66.6 g of silver nitrate and (99.92 / 0.08) An aqueous solution containing potassium bromide and potassium iodide in a molar ratio was added over 9 minutes by a controlled double jet method while maintaining the pAg at 7.7. Thereafter, 37 ml of an aqueous solution containing 7.4 g of silver nitrate and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 9.7 / 0.3) and iridium chloride are added in an amount of 1 / mol silver.
× 10 ^-4 mol was added over 1 minute by a controlled double jet method while keeping the pAg at 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%. Thus, cubic silver iodobromide grains having a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain a photosensitive silver halide emulsion 4. The average silver iodide content of the silver halide grains contained in Emulsion 4 was 0.1 mol%, and the silver iodide content on the grain surface was 0.3 mol%.

(Preparation of Photosensitive Silver Halide Emulsion 5) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 333 ml of an aqueous solution containing 66.6 g of silver nitrate and (99.96 / 0.04) An aqueous solution containing potassium bromide and potassium iodide in a molar ratio was added over 9 minutes by a controlled double jet method while maintaining the pAg at 7.7. Thereafter, 37 ml of an aqueous solution containing 7.4 g of silver nitrate and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 9.4 / 0.6) and iridium chloride were added in an amount of 1 / mol silver.
× 10 ^-4 mol was added over 1 minute by a controlled double jet method while keeping pAg at 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%. Thus, cubic silver iodobromide grains having a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain a photosensitive silver halide emulsion 5. The average silver iodide content of the silver halide grains contained in Emulsion 5 was 0.1 mol%, and the silver iodide content on the grain surface was 0.4 mol%.

(Preparation of Photosensitive Silver Halide Emulsion 6) Water 9
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 333 ml of an aqueous solution containing 66.6 g of silver nitrate and an aqueous solution containing potassium bromide were added to pAg7. The solution was added over a period of 9 minutes by the controlled double jet method while maintaining at 7. Thereafter, 37 ml of an aqueous solution containing 7.4 g of silver nitrate and (9
Aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 9.0 / 1.0) and iridium chloride in an amount of 1 / mol silver.
× 10 ^-4 mol was added over 1 minute by a controlled double jet method while keeping the pAg at 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%. Thus, cubic silver iodobromide grains having a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain photosensitive silver halide emulsion 6. The average silver iodide content of the silver halide grains contained in Emulsion 6 was 0.1 mol%, and the silver iodide content on the grain surface was 1.0 mol%.

Table 1 shows the iodine compositions of the above photosensitive silver halide emulsions 1 to 6.

Next, according to the method of Example 1 of JP-A-9-127463, silver behenate was prepared by the following method.

Preparation of Na Behenate Solution 34 g of behenic acid was added to 340 ml of isopropanol for 65 days.
Dissolved at ° C. Next, while stirring, a 0.25N aqueous sodium hydroxide solution was added so as to have a pH of 8.7. At this time, about 400 ml of the sodium hydroxide aqueous solution was required.
Next, the aqueous sodium behenate solution was concentrated under reduced pressure to adjust the concentration of sodium behenate to 8.9% by weight.

Preparation of silver behenate A solution of 30 g of ossein gelatin dissolved in 750 ml of distilled water was added with a 2.94 M silver nitrate solution to adjust the silver potential to 4.
00 mV. To this, 374 ml of the above sodium behenate solution was added at a speed of 44.6 ml / min at a temperature of 78 ° C. by using a controlled double jet method, and simultaneously a 2.94 M silver nitrate aqueous solution was supplied with a silver potential of 400 mV.
It was added so that it became. The amounts of sodium behenate and silver nitrate used at the time of addition were 0.092 mol and 0.101 mol, respectively.
Mole. After the addition was completed, the mixture was further stirred for 30 minutes, and the water-soluble salts were removed by ultrafiltration.

Preparation of Photosensitive Emulsion 1 This photosensitive silver halide emulsion 1 was added to this silver behenate dispersion.
Is added, and 100 g of an n-butyl acetate solution of polyvinyl acetate (1.2 wt%) is gradually added while stirring to form flocs of the dispersion, and then water is removed.
After two further water washes and removal of water, polyvinyl butyral (average molecular weight 3000) was used as a binder.
5wt% butyl acetate and isopropyl alcohol 1:
(2) After adding 60 g of the mixed solution with stirring, polyvinyl butyral (average molecular weight of 40) was added as a binder to the gel-like mixture of behenic acid and silver halide thus obtained.
00) and isopropyl alcohol.

Preparation of photosensitive emulsions 2 to 6 In the same manner as in photosensitive emulsion 1, photosensitive silver halide emulsion 2 was prepared.
Using Nos. To 6, photosensitive emulsions 2 to 6 were prepared.

Preparation of Photosensitive Material 1 The following layers were sequentially formed on the above support to prepare photosensitive material 1. The drying was performed at 75 ° C. for 5 minutes.

Coating on back side: A solution having the following composition was applied to a dry film thickness of 5 μm.

Polyvinyl butyral (10% isopropanol solution) 150 ml Dye-B 70 mg Dye-C 70 mg

[0235]

Embedded image

Photosensitive layer surface side coating Photosensitive layer: A solution having the following composition was applied. The amount of silver was 1.7 g / m ^2.
Thus, polyvinyl butyral as a binder was applied to a dry film thickness of 20 μm.

Photosensitive Emulsion 1 Amount giving 1.7 g / m ² in terms of silver sensitizing dye-1 (0.1% DMF solution) 2 mg Antifoggant-1 (0.01% methanol solution) 3 ml Antifoggant -2 (1.5% methanol solution) 8 ml Antifoggant-3 (2.4% DMF solution) 5 ml Phthalazone (4.5% DMF solution) 8 ml Developer-1 (10% acetone solution) 13 ml Hardening agent H (1% methanol / DMF = 4: 1 solution) 2 ml

[0238]

Embedded image

[0239]

Embedded image

Surface protective layer: A solution having the following composition was applied on the photosensitive layer so that the film thickness after drying was 2.5 μm.

Acetone 175 ml 2-propanol 40 ml methanol 15 ml cellulose acetate 8.0 g phthalazine 1.0 g 4-methylphthalic acid 0.72 g tetrachlorophthalic acid 0.22 g tetrachlorophthalic anhydride 0.5 g matting agent (average particle size 4 μm Monodispersed silica) 2 g

Preparation of photosensitive materials 2 to 6 Photosensitive materials 2 to 6 were prepared in the same manner as in the case of photosensitive material 1 using photosensitive emulsions 2 to 6.

Evaluation < Evaluation of photographic performance> After exposing the photographic material with a laser sensitometer equipped with an 820 nm diode, the photographic material was exposed to 120 mm.
After processing (developing) at 15 ° C. for 15 seconds, the obtained image was evaluated using a densitometer. The result of the measurement is Dmin, sensitivity (D
(Reciprocal of the ratio of the exposure amount giving a density 1.0 higher than min)
And the sample No. The sensitivity of 1 was set to 100 and expressed as relative sensitivity. Table 2 shows the results.

<Evaluation of storage stability with time> After storing the photosensitive material for 7 days under the following conditions, processing (development) at 120 ° C. for 15 seconds.
Then, the obtained image is evaluated using a densitometer, and the difference between Dmin under the condition A and Dmin under the condition B (Dmin (B)
-Dmin (A)). Table 2 shows the results.

Condition A 25 ° C. 55% Condition B 40 ° C. 80%

<Evaluation of Image Preservation> Two samples treated in the same manner as in the evaluation of photographic performance were stored, one at 25 ° C. and 55% light-shielded, and the other at 7 ° C. and 55%. After exposing to natural light for a day, the Dmin of both were measured. Table 2 shows the increase in Dmin obtained by the following equation.

(Increase in Dmin) = (Dmin after exposure to natural light)-(Dmin after light-shielded storage)

<Evaluation of Development Stability> After exposing the photosensitive material with a laser sensitometer equipped with an 820 nm diode, the photosensitive material was processed (developed) at 115 ° C. and 125 ° C. for 15 seconds, and the obtained image was subjected to density. It was measured with a meter. The evaluation was made based on the fluctuation width of the sensitivity (the reciprocal of the ratio of the exposure amount giving a density higher than Dmin by 1.0). Sensitivity fluctuation range of 10
It was represented by a relative value when 0 was set. Table 2 shows the results.

[0249]

[Table 1]

[0250]

[Table 2]

From Table 2, it can be seen that the light-sensitive material of the present invention has sensitivity, D
It can be seen that they are excellent in min, storage stability with time, image storage stability and development stability.

Example 2 (Preparation of photosensitive silver halide emulsions 7 to 11) In Example 1, except that the composition of the alkali halide was changed.
Photosensitive silver halide emulsions 7 to 11 having an iodine composition as shown in Table 3 were prepared in the same manner as in Example 1, and photosensitive materials 7 to 11 were prepared in the same manner as in Example 1.

[0253]

[Table 3]

Further, these were treated in the same manner as in Example 1. Table 4 shows the results.

[0255]

[Table 4]

From Table 4, it can be seen that the light-sensitive material of the present invention shows
It can be seen that they are excellent in min, storage stability with time, image storage stability and development stability.

Example 3 (Preparation of photosensitive silver halide emulsions 12 to 16) Example 1
In the same manner as in Example 1, except that the composition of the alkali halide was changed, photosensitive silver halide emulsions 12 to 16 having an iodine composition as shown in Table 5 were prepared in the same manner as in Example 1. Thus, photosensitive materials 12 to 16 were prepared.

[0258]

[Table 5]

Further, these were treated in the same manner as in Example 1. Table 6 shows the results.

[0260]

[Table 6]

From Table 6, it can be seen that the light-sensitive material of the present invention shows
It can be seen that they are excellent in min, storage stability with time, image storage stability and development stability.

Example 4 (Preparation of photosensitive silver halide emulsion 17) 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water
Is dissolved and adjusted to a temperature of 35 ° C. and a pH of 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate, an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of (98/2) and iridium chloride are converted to silver 1 1 × 10 ⁻⁴ mol per mol is p
Ag was added over 10 minutes by a controlled double jet method while keeping the Ag at 7.7. Then 4-hydroxy-
6-methyl-1,3,3a, 7-tetrazaindene
After adding 3 g and adjusting the pH to 5 with NaOH, the average particle size was 0.06 μm, the variation coefficient of the projected diameter area was 8%, and [1
00] Cubic silver iodobromide grains having an area ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then 0.1 g of phenoxyethanol was added thereto.
Ag was adjusted to 7.5 to obtain photosensitive silver halide emulsion 17. The average silver iodide content of the silver halide grains contained in Emulsion 17 was 2 mol%, and the average silver iodide content on the grain surface was 2 mol% (see Table 7).

(Preparation of Photosensitive Silver Halide Emulsion 18) 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, the temperature was adjusted to 35 ° C. and the pH was adjusted to 3.0, and then 74 g of silver nitrate was contained. 370 ml of aqueous solution and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 8.02 / 1.98) and iridium chloride at a concentration of 1 × 10 ⁻⁴ mol per mol of silver by a controlled double jet method while maintaining a pAg of 7.7. Added over 10 minutes. After the addition, 2.9 m of a 1% aqueous solution of potassium iodide was added.
After stirring for 5 minutes, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, and the average particle size was 0.04.
Cubic silver iodobromide grains having a size of 6 μm, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then 0.1 g of phenoxyethanol was added to the emulsion to give a pH of 5.9 and a pAg of 7.5.
To obtain a photosensitive silver halide emulsion 18. The average silver iodide content of the silver halide grains contained in the emulsion 18 is 2 mol%, and the average value of the silver iodide content on the grain surface is 4 mol%.
(See Table 7).

(Preparation of photosensitive silver halide emulsion 19) 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, the temperature was adjusted to 35 ° C. and the pH was adjusted to 3.0, and then 74 g of silver nitrate was contained. 370 ml of aqueous solution and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 8.02 / 1.98) and iridium chloride at a concentration of 1 × 10 ⁻⁴ mol per mol of silver by a controlled double jet method while maintaining a pAg of 7.7. Added over 10 minutes. Thereafter, a 1% solution of iodine ion releasing agent 56 was added to 25.
After adding 2 ml, an aqueous solution containing 1 g of an iodide ion release regulator sodium sulfite was added at a constant speed for 1 minute,
After adjusting to 9.0, the mixture was kept for 8 minutes, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, and then the pH was adjusted to 5.0 to adjust the average particle size. 0.06 μm, coefficient of variation of projected diameter area 8%, [10
0] Cubic silver bromide grains having an area ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then 0.1 g of phenoxyethanol was added thereto.
The mixture was adjusted to 7.5 to obtain a photosensitive silver halide emulsion 19. Table 7 shows the average silver iodide content of the silver halide grains contained in the emulsion 19 and the average value of the silver iodide content on the grain surface.

(Preparation of photosensitive silver halide emulsion 20) Photosensitive silver halide emulsion 20 was prepared in exactly the same manner as in preparation of photosensitive silver halide emulsion 19, except that iodine ion releasing agent 56 was changed to 29. did. Table 7 shows the average silver iodide content of the silver halide grains contained in the emulsion 20 and the average value of the silver iodide content on the grain surface.

[0266]

[Table 7]

Light-sensitive materials 17 to 20 were prepared in the same manner as in Example 1 by using light-sensitive silver halide emulsions 17 to 20.

Further, these were treated in the same manner as in Example 1. Table 8 shows the results.

[0269]

[Table 8]

It can be seen that the light-sensitive material of the present invention is excellent in sensitivity, Dmin, storage stability with time, image storage stability and development stability.

Example 5 (Preparation of Photosensitive Silver Halide Emulsion 21) 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water
Was dissolved and adjusted to a temperature of 35 ° C. and a pH of 3.0, and then 370 ml of an aqueous solution containing 74 g of silver nitrate (97.5 / 2.
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 5) and iridium chloride were added over 8 minutes by a controlled double jet method while maintaining a pAg of 7.5 at 1 × 10 ⁻⁵ mol per mol of silver. . 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 0.05 μm, and the variation coefficient of the projected diameter area was 9
%, [100] face ratio of 89%, to give cubic silver iodobromide grains. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, desalting treatment, and then 0.1 g of phenoxyethanol was added.
The mixture was adjusted to 5.9 and pAg 7.5 to obtain a photosensitive silver halide emulsion 21. The average silver iodide content of the silver halide grains contained in the emulsion 21 is 2.5 mol%, the average value of the silver iodide content on the surface of the grains is 2.5 mol%, and the distribution of the silver iodide content between grains. Was 38% (see Table 9).

(Preparation of Photosensitive Silver Halide Emulsion 22) 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, the temperature was adjusted to 35 ° C. and the pH was adjusted to 3.0, and then 74 g of silver nitrate was contained. 370 ml of aqueous solution and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 7.6 / 2.4) and iridium chloride are added in an amount of 1 / mol silver.
× 10 ⁻⁵ mol was added by a controlled double jet method over 8 minutes while keeping pAg at 7.5. Thereafter, after adding 25.2 ml of a 1% solution of an iodide ion releasing agent 56, sodium iodide ion releasing agent sodium sulfite 1 was added.
g was added over 5 seconds to adjust the pH to 9.0, and then maintained for 8 minutes to prepare 4-hydroxy-6-methyl-1,3,3.
0.3 g of 3a, 7-tetrazaindene was added and then the pH was adjusted to 5.0 to give an average particle size of 0.05 μm,
Variation coefficient of projected diameter area 9%, [100] face ratio 89%
Of cubic silver bromide particles were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain a photosensitive silver halide emulsion 22. The average silver iodide content of the silver halide grains contained in the emulsion 22 was 2.5 mol%, the average value of the silver iodide content on the grain surface was 12 mol%,
The intergranular distribution of the silver iodide content was 33% (see Table 9).

(Preparation of Photosensitive Silver Halide Emulsion 23) In the preparation of the photosensitive silver halide emulsion 22, the addition rate of the aqueous solution of sodium iodide ion-controlling agent sodium sulfite was adjusted to 20.
A light-sensitive silver halide emulsion 23 was obtained in the same manner as in the light-sensitive silver halide emulsion 22, except that the time was changed to seconds. The average silver iodide content of the silver halide grains contained in Emulsion 23 was 2.5
Mol%, the average value of the silver iodide content on the grain surface was 12 mol%, and the distribution of the silver iodide content between grains was 30% (Table 9).
reference).

(Preparation of Photosensitive Silver Halide Emulsion 24) In the preparation of the photosensitive silver halide emulsion 22, except that the addition rate of the aqueous solution of sodium iodide ion-controlling agent sodium sulfite was changed to 1 minute, A light-sensitive silver halide emulsion 24 was obtained in the same manner as in Emulsion 22. The average silver iodide content of the silver halide grains contained in the emulsion 24 was 2.5 mol%, the average silver iodide content on the grain surface was 12 mol%,
The intergranular distribution of the silver iodide content was 27% (see Table 9).

(Preparation of Photosensitive Silver Halide Emulsion 25) 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, the temperature was adjusted to 35 ° C. and the pH was adjusted to 3.0, and then 74 g of silver nitrate was contained. 370 ml of aqueous solution and (9
An aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 7.6 / 2.4) and iridium chloride were added in an amount of 1 × per mole of silver.
Controlling ^10-5 mol while maintaining pAg 7.5
It was added over 8 minutes by a double jet method. Thereafter, 11.5 ml of a 1% solution of potassium iodide was added, and the mixture was held for 8 minutes, and then 4-hydroxy-6-methyl-1,3,3 was added.
0.3 g of 3a, 7-tetrazaindene was added and then the pH was adjusted to 5.0 to give an average particle size of 0.05 μm,
Variation coefficient of projected diameter area 9%, [100] face ratio 89%
Of cubic silver bromide particles were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant, and after desalting, 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain a photosensitive silver halide emulsion 25. The average silver iodide content of the silver halide grains contained in the emulsion 25 was 2.5 mol%, the average silver iodide content on the grain surface was 12 mol%,
The intergranular distribution of the silver iodide content was 38% (see Table 9).

[0276]

[Table 9]

Light-sensitive materials 21 to 25 were prepared in the same manner as in Example 1 using the light-sensitive silver halide emulsions 21 to 25.

Further, these were treated in the same manner as in Example 1. Table 10 shows the results.

[0279]

[Table 10]

The light-sensitive materials 22 to 25 of the present invention have a higher iodine content on the surface of silver halide grains than the light-sensitive material 21 compared to the light-sensitive material 21, and have an internal sensitivity, Dmin, storage stability over time, image storage stability, and development. It turns out that it is excellent in terms of stability. Among them, it is found that photosensitive materials 22 to 24 having an iodine content distribution between grains of 35% or less are particularly excellent.

[0281]

According to the present invention, the stability of the photographic performance of the photothermographic material during storage with time is improved, and the stability of the image of the photothermographic material after development processing is improved. It is possible to provide a photothermographic material capable of improving the stability of photographic performance with respect to a temperature change during thermal development of the photosensitive material, a processing method thereof, and an image forming method.

Claims (7)

[Claims] 1. A photothermographic material comprising an organic silver salt, photosensitive silver halide grains, a reducing agent for silver ions and a binder on a support, wherein the photosensitive silver halide grains have a silver iodide content. A photothermographic material characterized in that the surface of the particles is higher than the inside of the particles. 2. The method according to claim 1, wherein the difference between the silver iodide content inside the photosensitive silver halide grains and the silver iodide content on the surface of the grains is 0.1 mol% or more and 40 mol% or less. 2. The photothermographic material according to item 1. 3. A photothermographic material comprising an organic silver salt, photosensitive silver halide grains, a reducing agent for silver ions and a binder on a support, wherein the silver iodide content of the photosensitive silver halide grains is determined. 3. The photothermographic material according to claim 1, wherein the distribution between the particles is 35% or less. 4. A photothermographic material comprising an organic silver salt, photosensitive silver halide particles, a reducing agent for silver ions, and a binder on a support, wherein the photosensitive silver halide particles have the following general formula (1): 4. The photothermographic material according to claim 1, wherein the photothermographic material is prepared in the presence of a compound represented by the formula (1). Formula (1) RI In the formula, R represents a monovalent organic acid residue that releases iodide ions by reaction with a base and / or a nucleophile. 5. The photothermographic material according to claim 1, wherein the photosensitive silver halide particles have infrared sensitivity. 6. A method for processing a photothermographic material, comprising subjecting the light-sensitive material according to claim 1 to heat development at a processing temperature of 80 ° C. or higher. 7. An image forming method, wherein the photosensitive material according to claim 5 is exposed to infrared light, and then heat-developed at a processing temperature of 80 ° C. or higher to obtain an image.