JP2003114506A - Exposure method and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure method for a silver salt photographic sensitive material by which high sharpness and graininess are obtained. SOLUTION: In the exposure method, a silver salt photographic sensitive material is exposed using a radiographic image conversion panel containing a phosphor of 10-100 nm crystallite size comprising oxygen atoms O and at least one rare earth element selected from gadolinium Gd and europium Eu.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exposing a silver salt photographic light-sensitive material, and more particularly to an exposure method for a silver salt photographic light-sensitive material which is excellent in sharpness and graininess and has high diagnostic ability.

[0002]

2. Description of the Related Art In radiographic diagnosis in medicine,
Radiation that has passed through the human body irradiates a radiation image conversion panel represented by a fluorescent intensifying screen or the like, is converted into fluorescence here, an image is formed on a photosensitive material, and diagnosis is performed based on the image. In the above-mentioned X-ray photography diagnosis, it is required that the sharpness of an image is good and the graininess is excellent in order to avoid early detection and misdiagnosis of lesions. The sharpness and graininess of the light-sensitive material itself are extremely important for enhancing the diagnostic ability because they affect the visibility of an image and the amount of information.
Further, in a normal chest X-ray photography, a region of the X-ray generation tube having a tube voltage of 110 kVp or higher is used. It is based on the quantum mottle of a line, and this quantum mottle greatly deteriorates the graininess and image quality of an X-ray photograph. A phosphor mainly containing a rare earth metal compound is used as a phosphor that is a main material constituting a radiation image conversion panel.

Conventionally, as these phosphors, Gd ₂ O has been used.
₂ S: Tb and the like have been mainly used, and these were prepared by repeating the steps of mixing a rare earth oxide and a sulfur compound, adding a flux and firing and crushing. For this reason, the produced phosphor does not have a uniform particle shape, cracks occur in the crystal due to physical stress during crushing or cooling, and the prepared phosphor has a disordered particle structure and an uneven particle shape. Also, the particle size distribution will be broadened. When a phosphor layer is formed using such a phosphor, it is impossible to make the phosphor distribution uniform in the radiation direction in the phosphor layer. For example, the phosphors are not evenly dispersed because the particle shapes are not uniform, and regions with high density and low density of the phosphor are generated, and even if the intensity of the irradiated radiation is equal, a uniform light emission amount cannot be obtained. . Even if the phosphor can be dispersed uniformly, the amount of light emission will be different between the part where the particle size of the phosphor is large and the part where the particle size of the phosphor is small, even if the intensity of the radiation is the same. Further, when the phosphors are not uniformly dispersed or the particle shapes are not uniform, the radiation is randomly scattered. For this reason, it is not possible to correctly obtain light emission according to the intensity of the applied radiation, which causes blurring of the radiation image. Further, in the radiation image conversion panel manufactured in this manner, the X-ray quantum mottle is greatly deteriorated, and only an image having poor sharpness and graininess is obtained, which is not preferable for medical image diagnosis.

In recent years, the amount of a simple recording medium called a dry film which does not require a wet process has been increasing. It can be said that the dry film is very easy to handle because the processing device used for the development processing of these dry films does not require piping and is not a complicated device because it does not discharge the waste liquid. Further, the dry film has an excellent feature that the development processing time is short. However, it was not possible to directly record on a dry film by using a conventional radiation image conversion panel.
Further, in recent years, the photosensitive material is not directly exposed to the fluorescence of the radiation image conversion panel, but the information obtained from the radiation conversion panel is once converted into an electrical signal and processed as digital data.
A so-called laser imager, which exposes a photosensitive material using a laser beam capable of obtaining a high light amount, has become widespread. By using these, it is possible to record on dry film, but when exposing with a laser imager, image data is processed as digital data by the sampling theorem, so there is no loss of high frequency data that is important for image sharpness. Occur. In addition, the image quality is greatly affected by the shape and scanning of the laser beam, and in reality, it is not always possible to obtain a high quality image. Therefore, the dry film has not been suitable for obtaining an image that requires very high image quality, for example, an image obtained by photographing a breast.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a method of exposing a silver salt photographic light-sensitive material capable of obtaining high sharpness and graininess. A further object of the present invention is to provide a method for exposing a silver salt photothermographic dry imaging material which can obtain high sharpness and graininess.

[0006]

The above objects of the present invention are as follows: (1) A phosphor having a crystallite size of 10 to 100 nm, which contains at least one oxygen atom O and a rare earth element selected from gadolinium Gd and europium Eu. An exposure method comprising exposing a silver salt photographic light-sensitive material using a radiation image conversion panel containing the. (2) The above-mentioned (1) wherein the phosphor is a phosphor containing a phosphor represented by the formula (Gd, M, Eu) ₂ O ₃ (M represents a rare earth element) as a constituent element. ) The exposure method according to [4]. (3) The rare earth element M is yttrium Y, niobium Nd,
Terbium Tb, Dysprosium Dy, Holmium H
o, Erbium Er, Thulium Tm, Ytterbium Y
The exposure method according to (2) above, which is at least one selected from b. (4) In the formula (Gd, M, Eu) ₂ O ₃ , gadolinium Gd is 40 to 95% by mass, M is 5 to 40% by mass, and europium Eu is 2 to 20% by mass. The exposure method according to 2) or (3). (5) The exposure method according to any one of (1) to (4) above, wherein the phosphor particles are particles having an average particle size of 0.2 to 5 μm. (6) Silver having a photosensitive layer formed by coating a composition containing a silver halide photographic light-sensitive material, a photosensitive emulsion containing organic silver salt particles, photosensitive silver halide particles and a solvent, a reducing agent and a binder. The exposure method according to any one of (1) to (5) above, which is a salt photothermographic dry imaging material. (7) The silver salt photothermographic dry imaging material exposed by the exposure method according to (6) above is heated to 80 ° C. or higher and 200 ° C. or higher.
An image forming method comprising: developing by heating at the following temperature. Achieved by

The present invention will be described in detail below. First, the radiation image conversion panel of the present invention will be described. The radiation image storage panel used in the present invention has an oxygen atom O
And a crystallite size 10 containing at least one rare earth element selected from gadolinium Gd and europium Eu
Contains ~ 100 nm phosphor. The phosphor used in the radiation image conversion panel has the formula (Gd, M, Eu) ₂ O ₃ (M
Represents a rare earth element. ), Further, the rare earth element M is preferably at least one selected from yttrium Y, niobium Nd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb. . Further, in the formula (Gd, M, Eu) ₂ O ₃ , gadolinium Gd is preferably 40 to 95% by mass, M is 5 to 40% by mass, and europium Eu is preferably 2 to 20% by mass. The phosphor used in the radiation image conversion panel has a crystallite size of 10 to 100 nm and an average particle size of 0.
Phosphor particles that are 2-5 μm are preferred. The phosphor particles emit light according to the intensity of the incident radiation.

The radiation image conversion panel comprises a phosphor layer formed of the above-mentioned phosphor, and the phosphor layer may be, for example, a self-supporting phosphor layer. It may be a phosphor layer provided on the surface. The radiation image storage panel used in the present invention has a phosphor layer formed of a phosphor. The phosphor layer may be composed of only an aggregate of phosphors formed by a vapor deposition method or a sintering method, or may be composed of a phosphor and a binder for dispersing and supporting the phosphor. Further, the above-mentioned agglomerates can be impregnated with a polymer substance in the gaps. In addition, a protective layer film made of a polymer film or a vapor deposition film of an inorganic material can be provided on the phosphor layer. A protective layer film can be provided on one surface or both surfaces of the self-supporting phosphor layer and on the surface of the phosphor layer provided on the surface of the support opposite to the support side. Although the phosphor varies depending on the photosensitivity of the silver salt photographic light-sensitive material exposed by using the radiation image conversion panel, a phosphor having an emission wavelength in the wavelength range of 300 to 900 nm is generally used. That is, electromagnetic waves (light) centered on visible light and extending from ultraviolet light to infrared light
Is output.

In X-ray diagnostics in the medical field and other fields, for example, X-rays having a wavelength of about 1Å (1 × 10 ^-10 m) that penetrates an object of X-ray diagnostics are used. A suitable wavelength and intensity of X-ray are selected depending on the transparent material. Radiation that has passed through human bodies, ships and members of aircraft is irradiated on a radiation image conversion panel typified by a fluorescent intensifying screen, where it is converted into fluorescence and an image is formed on the silver salt photographic light-sensitive material. Diagnosis is made based on. This X-ray is output from the radiation generator, and a fixed anode or a rotating anode X-ray tube is generally used as the anode of the radiation generator. The voltage applied to the anode of the X-ray tube is usually 10 kV to 300 kV. When used for medical purposes, the voltage applied to the anode of the X-ray tube is 2
It is set from 0 kV to 150 kV.

In the present invention, the radiation image conversion panel is formed by using a phosphor having a crystallite size of 10 to 100 nm containing at least one oxygen atom O and a rare earth element selected from gadolinium Gd and europium Eu. . The phosphor particles having such a composition have a high radiation absorptivity, a high light emission efficiency, and a large amount of light emission, so that a radiation image with good graininess can be obtained. In particular, the phosphor has the formula (Gd, M,
In the case of the phosphor represented by Eu) ₂ O ₃ (M represents a rare earth element), since the emission efficiency is particularly high, it is possible to obtain a radiographic image with better graininess. here,
As the rare-earth element M, yttrium Y, niobium Nd, terbium Tb, dysprosium Dy, holmium Ho,
When at least one of erbium Er, thulium Tm, and ytterbium Yb is used, since these elements have a high radiation absorptivity, it is possible to obtain a radiation image with better graininess. In the above case, gadolinium Gd is 40
~ 95 wt%, M 5-40 wt%, Europium Eu
By setting 2 to 20% by mass, the radiation absorption rate and the luminous efficiency can be increased. Particularly, gadolinium Gd is 70-
90% by mass is preferable, and europium Eu is preferably 5 to 10% by mass.

The crystallite size, which is an index showing the size of the crystallites constituting the phosphor particles, is 10 to 100 nm. If the crystallite size is smaller than 10 nm, the light emission efficiency is low, and if it is larger than 100 nm, the phosphor collection rate during fabrication is deteriorated. The average particle size of the phosphor particles is preferably 0.2 to 5 μm. Average particle size is 0.2
If it is smaller than μm, the light emission efficiency is low, and if it is larger than 5 μm, the scattering of light emission in the radiation image conversion panel becomes large and the sharpness deteriorates. Further, the average particle size of the phosphor particles is preferably 0.5 to 2 μm. The crystallite size is
Kyoritsu Shuppan Co., Ltd. Edition Instrumental Analysis Practical Series Using the method described in X-ray analysis method, the “Wilson method” is used in which 10 to 15 measurable peaks of diffraction peaks obtained by X-ray diffraction are selected and measured. It was calculated. Regarding the particle size of the phosphor particles, the phosphor particles are dispersed in water by using a suitable surfactant, and the particle size is measured using a light scattering method particle measuring device (for example, Horiba LA910). You can ask. Here, the particle size of the phosphor particles is measured by dispersing the phosphor in water using a suitable surfactant and using a light scattering particle measuring device (for example, LA910, Horiba Seisakusho).

The shape of the phosphor particles is preferably spherical. This is because the spherical shape enhances the dispersibility of the phosphor particles in the binder and increases the filling rate of the phosphor particles in the binder, so that the graininess can be improved. Next, a method for manufacturing the phosphor used in the radiation image storage panel of the present invention will be described. Phosphor particles used in the radiation image conversion panel of the present invention, urea is added to an aqueous solution containing a salt of a rare earth element to precipitate a basic carbonate to cause precipitation, and the resulting precipitate is subjected to solid-liquid separation. 500
It can be obtained by baking at a temperature of not less than ° C.

Next, the formula (Gd, M, Eu) ₂ O ₃ (M is
Represents a rare earth element. The case where yttrium Y is used as the rare earth element M in the phosphor shown in () will be specifically described. An aqueous solution containing the rare earth elements gadolinium Gd, yttrium Y, and europium Eu is heated at 80 ° C. or higher for 0.5 to 5 hours, urea or urea and hydrogen peroxide are added, and the mixture is further heated to obtain the basic carbonate of the rare earth element. Spherical particles of salt are precipitated, and the precipitated basic carbonate of rare earth element is subjected to solid-liquid separation to obtain spherical particles of basic carbonate of rare earth element. The amount of urea added is preferably about 3 to 5 times the concentration of rare earth elements, and the amount of hydrogen peroxide added is preferably 1/100 to 30/100 with respect to the concentration of rare earth ions. By further firing the obtained basic carbonate spherical particles in air or in an oxidizing atmosphere, rare earth element oxide spherical particles can be obtained. The firing temperature is preferably 500 ° C or higher.

In the above description, spherical particles of basic carbonate of rare earth element are deposited, but the salts of rare earth element to be deposited are organic phosphate, malonate, glycolate, sebacate, cacodylate. And salts of many benzenesulfonic acid derivatives, aminopolyacetates (EDTA, DCTA,
HEDTA, DE, ME, NTA, IMDA salt), or acetylacetonate, alkoxide, cyclooctatetraene complex, cyclopentadiene complex. Examples of the aqueous solution containing a salt of a rare earth element include aqueous solutions of hydrochlorides, sulfates, nitrates, etc. Among them, aqueous solutions of nitrates are preferable. The amount of hydrogen peroxide added is 1/10 of the rare earth ion concentration.
It is preferable to add it in an amount of 0 to 30/100, and it is preferable that the amount of urea added be about 3 to 5 times that of the rare earth element. The basic carbonate of the obtained rare earth element is added at 500 ° C.
By firing as described above, spherical rare earth element oxide particles that retain the spherical shape of the basic carbonate can be obtained, and the oxide particles are used as a phosphor.

The phosphor particles thus obtained have a spherical particle shape and a narrow particle size distribution. Therefore, the dispersibility of the phosphor particles in the binder is high, the uniformity of the phosphor distribution in the radiation irradiation direction can be improved, and the filling rate of the phosphor particles in the binder can also be increased, so that the graininess can be improved. And a good radiation image can be obtained. Further, since the radiation is less scattered in the radiation image conversion panel, a radiation image with less blur can be obtained. The produced phosphor powder is dispersed in a binder and molded into a radiation image conversion panel. As the binder, for example, polyurethane, polyester, vinyl chloride copolymer (for example, vinyl chloride-acrylonitrile copolymer), butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (for example, nitrocellulose), Examples thereof include a styrene-butadiene copolymer, a synthetic rubber-based polymer, a phenol resin, an epoxy resin, a urea resin, a melanin resin, a phenoxy resin, a silicone resin, an acrylic resin, and a urea formamide resin. Among them, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral and nitrocellulose are preferably used. These preferable binders can enhance the dispersibility of the phosphor and the filling rate of the phosphor, and can contribute to the improvement of graininess.

The weight content of the phosphor dispersed in the binder is 90 to 99%. The thickness of the radiation image conversion panel layer is determined from the balance between the graininess and the sharpness of the radiation image. If the radiation image conversion panel layer is thick, the graininess is improved but the sharpness is deteriorated. If the radiation image conversion panel layer is thin, the sharpness is improved but the graininess is deteriorated. . Further, in order to obtain good graininess and sharpness, the thickness is preferably 50 μm to 300 μm. When the radiation image storage panel is composed of a support and a phosphor layer provided on the surface thereof, various polymer materials, glass, metal and the like can be used as the support. From the viewpoint of handling, the radiation image conversion panel is preferably a flexible radiation image conversion panel sheet or web, and in this respect, the support is a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyamide film, A plastic film such as a polyimide film, a triacetate film or a polycarbonate film, a metal sheet of aluminum, iron, copper, chromium or the like or a metal sheet having a coating layer of the metal oxide is preferable. The layer thickness of the support varies depending on the material of the support used and the like, but is generally 3 μm to 1000 μm, and from the viewpoint of handling, more preferably 80 μm to
It is 500 μm. The surface of these supports may be a smooth surface, or may be a matte surface in order to improve the adhesiveness with the phosphor layer. Further, these supports may be provided with an undercoat layer in order to improve the adhesiveness with the phosphor layer.

The phosphor used in the present invention has a high hygroscopic property except for a part thereof, and therefore it is preferable to use it in a sealed state so as not to be affected by environmental humidity. For sealing, for example, JP-A No. 11-223890 and JP-A No. 11-223890.
The methods disclosed in JP-A-249243, JP-A-11-344598, and JP-A-2000-171597 can be used, and the entire radiation image conversion panel can be sealed.

Next, the silver salt photographic light-sensitive material used in the present invention will be described. The silver salt photographic light-sensitive material exposed by the exposure method of the present invention is not particularly limited, and any silver salt photographic light-sensitive material may be used as long as it is a silver salt photographic light-sensitive material. A silver salt photographic light-sensitive material for carrying out, for example, a silver salt photothermographic dry imaging material which is a photothermographic image forming material is preferable. Organic silver salt particles, photosensitive silver halide particles and a reducing agent are used in the silver salt photothermographic dry imaging material. The photosensitive silver halide functions as an optical sensor, and the organic silver salt is reduced with a reducing agent to form an image.

The details of the silver salt photothermographic dry imaging material are described in, for example, US Pat. Nos. 3,152,904, 3,457,075 and D. "Dry Silver Photographic Materials (D
ry Silver Photographic Ma
Tial) "and D.I. Morgan and B.M. “Thermal Processes by Heat (Thermally Process)” by Shelly
ed Silver Systems ”(Imaging Processes and Materials (Imagin)
g Processes and Material
s) Neblette 8th Edition, Sturg
e), V. Wallworth, A.S.
Shepp, edited, page 2, 1969) and the like.

The silver salt photographic light-sensitive material will be sequentially described below by taking a silver salt photothermographic dry imaging material as an example. As the organic silver salt used in the silver salt photothermographic dry imaging material, for example, silver salts of organic acids and heteroorganic acids are used.
0-30, preferably 15-25) silver salts of aliphatic carboxylic acids and silver salts of nitrogen-containing heterocyclic compounds are preferred. Also,
The total stability of the ligand to silver ions is 4.0 to 4.0.
Research Disclosures (hereinafter sometimes abbreviated as RD) 17029 and 29 having a value of 10.0
The organic or inorganic complexes described in 963 are also preferred.
Examples of these suitable silver salts include the following. Silver salts of organic acids such as gallic acid, oxalic acid, behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid; silver carboxyalkylthiourea salts,
For example, 1- (3-carboxypropyl) thiourea, 1
Silver salt such as-(3-carboxypropyl) -3,3-dimethylthiourea; Silver salt or complex of polymer reaction product of aldehyde and hydroxy-substituted aromatic carboxylic acid, for example, aldehydes (eg, formaldehyde, acetaldehyde, Butyraldehyde etc.) and a hydroxy-substituted acid (eg salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid) reaction product silver salt or complex; thione silver salt or complex, eg 3- (2-carboxyl) Ethyl) -4-hydroxymethyl-4-thiazoline-2-thione, and 3-carboxymethyl-4-thiazoline-2
-Silver salts or complexes such as thione; imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,
Complexes or salts of silver with a nitric acid selected from 4-triazole and benztriazole; silver salts such as saccharin and 5-chlorosalicylaldoxime; silver salts of mercaptides. Among these, particularly preferred silver salts include silver salts of long-chain (C10-30, preferably 15-25) aliphatic carboxylic acids such as silver behenate, silver arachidate and silver stearate. . Further, in the present invention, it is preferable that two or more kinds of organic silver salts are mixed in order to improve developability and form a silver image of high density and high contrast. It is preferable to prepare by mixing the solutions.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver. The forward mixing method, the reverse mixing method, the simultaneous mixing method, and JP-A-9-12764.
The controlled double jet method and the like as described in Japanese Patent No. 3 are preferably used. For example, after adding alkali metal salt etc. (eg sodium hydroxide, potassium hydroxide etc.) to organic acid to make organic acid alkali metal salt soap (eg sodium behenate, sodium arachidate etc.) Crystals of an organic silver salt can be produced by mixing the soap with silver nitrate or the like by the jet method. At the time of production, photosensitive silver halide grains may be mixed.

The organic silver salt particles may have any shape, but tabular particles are preferred. In particular, it is a tabular organic silver salt grain having an aspect ratio of 3 or more, and the shape anisotropy of two substantially parallel faces (main planes) having a maximum area is small, so that filling in the photosensitive layer is possible. For this purpose, particles having an average acicular ratio of the tabular organic silver salt particles measured from the main plane direction of 1.1 or more and less than 10.0 are preferable. A more preferable acicular ratio is 1.1 or more and 5.0.
Is less than. In the present invention, the tabular organic silver salt particles having an aspect ratio of 3 or more mean that the tabular organic silver salt particles having an aspect ratio of 3 or more account for 50% or more of the total number of organic silver salt particles. Say. Furthermore, the aspect ratio is 3
The total number of tabular organic silver salt particles is 60 in total.
%, More preferably 70% or more, especially 80% or more, the organic silver salt particles are preferable.

In the present invention, the tabular grains having an aspect ratio of 3 or more are grains having a ratio of grain size to thickness and a so-called aspect ratio (hereinafter abbreviated as AR) represented by the following formula of 3 or more. . AR = particle size (μm) / thickness (μm) The aspect ratio of the organic silver salt particles used in the photothermographic image forming material used in the present invention is preferably 3 to 20, and more preferably 3 to 10. . If the aspect ratio is too low, the organic silver salt particles are likely to be most closely packed, and if the aspect ratio is too high, the organic silver salt particles are likely to overlap with each other and are dispersed in a sticky state. As a result, light scattering is likely to occur, and as a result, the transparency of the photosensitive material is deteriorated.

There is no particular method for obtaining the organic silver salt particles having the above-mentioned shape, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the organic acid alkali metal salt soap It is an effective means to keep a good mixed state when adding silver nitrate, and to optimize the ratio of silver nitrate that reacts with the organic acid alkali metal salt soap. It is preferable that the organic silver salt particles are pre-dispersed together with a binder, a surfactant and the like, if necessary, and then dispersed and pulverized by a media disperser or a high pressure homogenizer. For pre-dispersion, a general stirrer such as anchor type and propeller type, high speed centrifugal centrifugal stirrer (dissolver),
A high speed rotary shear stirrer (homomixer) can be used.

As the media disperser used for the above dispersion and pulverization, a rolling mill such as a ball mill, a planetary ball mill, a vibrating ball mill, a bead mill as a medium agitating mill, an attritor, or another basket mill may be used. As the high-pressure homogenizer, it is possible to use a type in which the liquid collides against a wall, a plug, etc., a type in which the liquids are divided into a plurality of liquids and then collide with each other at a high speed, a type in which the liquids pass through a narrow orifice, and the like.

In the present invention, a preferable silver salt photothermographic dry imaging material is 0.025 μm ² when the section of the material perpendicular to the support surface is observed with an electron microscope.
The proportion of organic silver salt particles exhibiting a projected area of less than 70% or more of the total projected area of the organic silver salt particles, and 0.2 μm
^A silver salt photothermographic dry obtained by coating a photosensitive emulsion containing an organic silver salt or a photosensitive silver halide in which the proportion of grains having a projected area of ² or more is 10% or less of the total projected area of the organic silver salt grains. It is an imaging material. In this silver salt photothermographic dry imaging material, it is possible to obtain a state in which organic silver salt particles are less aggregated and uniformly distributed in the photosensitive emulsion. The conditions for producing the photosensitive emulsion having such characteristics are not particularly limited, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap are favorably set. Keeping it, optimizing the proportion of silver nitrate that reacts with soap, dispersing and pulverizing by dispersing with a media disperser or a high pressure homogenizer, and adding a binder concentration of 0.1 to 10% of the organic silver mass. In addition to the fact that the temperature from drying to the end of the main dispersion does not exceed 45 ° C, a dissolver is used to adjust the peripheral speed to 2.0 m.
A preferable condition is to stir at a speed of at least 1 second.

In the present invention, in order to prevent devitrification of the light-sensitive material, the total amount of silver halide and organic silver salt is preferably 0.5 g or more and 2.2 g or less per 1 m ² in terms of silver amount. . By setting it in this range, a preferable image as a medical image can be obtained.

Next, the photosensitive silver halide grains used in the silver salt photothermographic dry imaging material will be described. The photosensitive silver halide grain in the present invention is, as a unique property of a silver halide crystal, inherently absorbing light, or absorbing visible light or infrared light by an artificial physicochemical method. And when a light in any region within the light wavelength range from the ultraviolet light region to the infrared light region is absorbed, a physicochemical change may occur in the silver halide crystal and / or the crystal surface. It means a processed and produced silver halide crystal grain. The silver halide grains themselves used in the present invention are described in P. Chif by Glafkides
Mie et Physique Photograph
hique (published by Paul Montel, 1967
Year), G. F. Duffin Photograph
ic Emulsion Chemistry (The
Focal Press, 1966), V.I. L.
Making and by Zelikman et al
Coating Photographic Emu
Ision (published by The Focal Press, 19
64) and the like to prepare a silver halide grain emulsion. That is, for the preparation, any method such as an acidic method, a neutral method, an ammonia method or the like may be used, and as a method of reacting the soluble silver salt and the soluble halogen salt, a one-sided mixing method, a simultaneous mixing method, Any combination thereof may be used.

As a method for adjusting the silver halide grains, the so-called controlled double jet method of preparing the silver halide grains while controlling the forming conditions among the above methods is preferable because the grain shape and size can be controlled. The halogen composition of the silver halide grains is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide. The formation of silver halide grains is usually carried out in two stages of silver halide seed grain (nucleus) generation and grain growth. Particle formation and particle growth may be performed separately. At this time, pAg,
A controlled double jet method in which particles are formed by controlling pH and the like can be used. The method of separating the formation of nuclei (seed particles) and the growth of grains is first performed by a nucleation step of rapidly and uniformly mixing soluble silver salt and soluble halogen salt in an aqueous gelatin solution to form nuclei (seed particles). Then, a silver halide grain can be prepared by performing a grain growth step of growing a grain while supplying a soluble silver salt and a soluble halogen salt under controlled pAg, pH and the like. After the grain formation, unnecessary salts are removed by a desalting step by a known desalting method such as noodle method, flocculation method, ultrafiltration method, electrodialysis method to obtain a desired silver halide emulsion. Obtainable. It can also be used without desalting.

The average grain size of silver halide grains is preferably small in order to suppress white turbidity after image formation and obtain good image quality, and the average grain size is 0.2 μm or less.
More preferably 0.01 μm to 0.17 μm, especially 0.1.
02 μm to 0.14 μm is preferable. Here, the grain size means the length of a ridge of a silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. When the silver halide grain is a tabular grain, it means the diameter of a circle having the same area as the projected area of the main surface. The grain size distribution of silver halide grains is preferably monodisperse. The monodisperse as used herein means that the variation coefficient of the particle size distribution calculated by the following formula is 30% or less. The variation coefficient is preferably 20% or less, more preferably 15% or less. Coefficient of variation of particle size distribution%
= Standard deviation of grain size / average value of grain size × 100 The shape of the silver halide grain is cubic, octahedral, tetradecahedral grain, tabular grain, spherical grain, rod-shaped grain, potato-shaped grain, etc. Among them, cube, octahedron, tetrahedron,
Tabular silver halide grains are preferred.

The tabular silver halide grains preferably have an average aspect ratio of 1.5 or more and 100 or less,
It is more preferably 2 or more and 50 or less. Methods for preparing these tabular silver halide grains are described in US Pat. No. 5,264,3
No. 37, No. 5,314,798, No. 5,320,958, etc., and the desired tabular grains can be easily obtained. Further, as the silver halide grains, grains having rounded corners can also be preferably used. The crystal habit on the outer surface of the silver halide grain to be used is not particularly limited, but it is a spectral sensitizing dye having spectral habit (face) selectivity for adsorbing the silver sensitizing dye on the surface of the silver halide grain. When a dye is used, it is preferable to use silver halide grains having a relatively high proportion of crystal habit adapted to the selectivity. For example, when a sensitizing dye that is selectively adsorbed on a crystal plane having a Miller index (100) is used, the proportion of the (100) plane on the outer surface of the silver halide grain is preferably high, and this proportion is 50. % Or more, and even 7
It is preferably 0% or more, and particularly preferably 80% or more. The ratio of Miller index (100) planes is measured by T.W. Tani, J .; ImagingSci. , 2
9, 165 (1985).

The silver halide grains may be added to the image forming layer by any method, and it is preferable that the silver halide grains are arranged in the vicinity of the reducible silver source (organic silver salt).

In order to arrange the silver halide grains close to the reducible silver source (organic silver salt), the silver halide is prepared in advance, and this is used as a solution for preparing the organic silver salt grains. It can be carried out by adding to. This method is preferable from the viewpoint of controlling the production conditions because the silver halide preparation step and the organic silver salt grain preparation step can be handled separately. In order to arrange the silver halide grains in the vicinity of the reducible silver source (organic silver salt), organic silver salt grains can be prepared as described in British Patent No. 1,447,454. When a halogen component such as a halide ion is made to coexist with an organic silver salt-forming component in the preparation of, and by injecting silver ions into the component, the silver halide grains are formed almost at the same time as the formation of the organic silver salt grains. You can

It is also possible to react the organic silver salt with a halogen-containing compound to prepare silver halide grains by conversion of the organic silver salt. For example, in a solution or dispersion of an organic silver salt prepared in advance,
Alternatively, it can also be carried out by reacting a sheet material containing an organic silver salt with a silver halide-forming component to convert a part of the organic silver salt into a photosensitive silver halide. In this case, as the silver halide-forming component, inorganic halogen compounds, onium halides, halogenated hydrocarbons, N-
Halogen compounds and other halogen-containing compounds are used, and specific examples thereof include US Pat. No. 4,009,03.
No. 9, No. 3,457,075, No. 4,003,749, British Patent No. 1,498,
No. 956, JP-A-53-27027, and JP-A-53-27027.
A metal halide detailed in JP-A-3-25420,
Inorganic halides such as ammonium halides, for example, onium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, trimethylbenzylammonium bromide, for example, iodoform, bromoform, carbon tetrachloride, 2-bromo-2. -Halogenated hydrocarbons such as methylpropane, N-halogen compounds such as N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, and others, for example, triphenylmethyl chloride,
Triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, dichlorobenzophenone and the like can be mentioned.
Thus, the silver halide can also be prepared by reacting an organic acid silver salt with a halogen ion to convert the silver in the organic acid silver salt into a silver halide. Further, as the silver halide, a separately prepared silver halide grain and a silver halide grain obtained by converting a part of an organic silver salt may be used in combination. The silver halide grains, regardless of the silver halide obtained, are 0.001 mol per mol of the organic silver salt.
It is preferable to use 1 mol to 0.7 mol, preferably 0.03 mol to 0.5 mol.

[Chemical Sensitizer] The silver halide grains used in the silver salt photothermographic dry imaging material of the present invention can be chemically sensitized. For example, Japanese Patent Application No. 12-057
Chemical sensitization center by the use of a compound that releases a chalcogen such as sulfur or a noble metal compound that releases a noble metal ion such as gold ion by the method disclosed in Japanese Patent Application No. 004 and Japanese Patent Application No. 12-061942. (Chemical sensitization nucleus) can be formed and imparted. In the present invention, it is preferably chemically sensitized with an organic sensitizer containing a chalcogen atom such as sulfur, selenium or tellurium. The organic sensitizer containing these chalcogen atoms is preferably a compound having a group capable of adsorbing to silver halide and an unstable chalcogen atom site. Examples of these organic sensitizers include JP-A-60-150046 and JP-A-4-10.
The organic sensitizers having various structures disclosed in JP-A No. 9240 and JP-A No. 11-218874 can be used. Among them, when the chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond. It is preferable that the compound is at least one kind of compound having the above structure. The amount of chalcogen compound used is the amount of chalcogen compound used,
It depends on the silver halide grains and the reaction environment at the time of chemical sensitization, but in general, it is 1 per mol of silver halide.
0 ^-8 to 10 ^-2 mol is used, preferably 10 ^-7 to 10
^-3 mol.

There are no particular restrictions on the environment for chemical sensitization, but it is preferable to carry out the chemical sensitization in the absence of an organic acid silver salt such as silver behenate. Also, the chalcogenation formed on the silver halide grains is preferable. In the presence of a compound capable of eliminating silver or silver nuclei or reducing their size, in particular:
It is also preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the coexistence of an oxidant capable of oxidizing silver nuclei.
Is preferably 6 to 11, more preferably 7 to
10, the pH is preferably 4-10, more preferably 5-8, and the temperature is 30 ° C.
The sensitization is preferable below. Therefore, in the silver salt photothermographic dry imaging material of the present invention, the photosensitive silver halide uses an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing the silver nucleus on the grain. It is preferable to use a photosensitive emulsion which has been subjected to chemical sensitization at a temperature of 30 ° C. or lower, mixed with an organic silver salt, dispersed, dehydrated and dried.

The chemical sensitization using an organic sensitizer is also preferably carried out in the presence of a spectral sensitizing dye or a hetero atom-containing compound having adsorptivity to silver halide grains. By performing chemical sensitization in the presence of a compound having adsorptivity to silver halide, it is possible to prevent the chemical sensitization central nucleus from being dispersed, and to achieve high sensitivity and low fog. The spectral sensitizing dye used will be described later, but the heteroatom-containing compound having adsorptivity to silver halide is described in JP-A-3-2.
The nitrogen-containing heterocyclic compound described in Japanese Patent No. 4537 is mentioned as a preferable example. Examples of the heterocycle contained in these nitrogen-containing heterocyclic compounds include a pyrazole ring, a pyrimidine ring, a 1,2,4-triazole ring, 1,2,3
-Triazole ring, 1,3,4-thiadiazole ring,
1,2,3-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,
3,4-tetrazole ring, pyridazine ring, 1,2,3-
Examples thereof include a triazine ring and a ring in which two or three of these rings are bonded, such as a triazolotriazole ring, a diazaindene ring, a triazaindene ring, and a pentaazaindene ring. Further, a heterocycle in which a monocyclic heterocycle and an aromatic ring are condensed, for example, a phthalazine ring, a benzimidazole ring, an indazole ring, a benzthiazole ring and the like can be mentioned. Among these, an azaindene ring is preferable, and an azaindene compound having a hydroxy group as a substituent, such as hydroxytriazaindene, tetrahydroxyazaindene, and hydroxypentaazaindene, is more preferable. The heterocycle may have a substituent other than a hydroxy group, for example, an alkyl group, a substituted alkyl group, an alkylthio group, an amino group, a hydroxyamino group,
It may have an alkylamino group, a dialkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, a halogen atom, a cyano group and the like. The addition amount of the heterocyclic ring containing compound varies over a wide range depending on the size and composition of silver halide grains, but an approximate amount per mole of silver halide 10 ^-6 mol to 1 It is in the range of mol, preferably 10 ^-4 mol to 10 ^-1.
It is in the molar range.

As described above, the silver halide grains can be sensitized with a noble metal using a compound that releases a noble metal ion such as gold ion. For example, a chloroauric acid salt or an organic gold compound can be used as the gold sensitizer. In addition to the above-mentioned sensitization method, a reduction sensitization method or the like can be used. As the shell-like compound used for the reduction sensitization, ascorbic acid, thiourea dioxide, stannous chloride, a hydrazine derivative, Examples thereof include borane compounds, silane compounds and polyamine compounds. Also, the pH of the emulsion should be 7 or more or pAg
Can be sensitized by reduction by aging while maintaining the value of 8.3 or less. Chemically sensitized silver halide is
It may be formed in the presence of an organic silver salt, may be formed under the condition in which no organic silver salt is present, or may be a mixture of both.

[Dopant Doping to Silver Halide]
The silver halide used in the present invention has
Contains ions of transition metals belonging to groups 6 to 11
It is preferable. The above metals include W, Fe, C
o, Ni, Cu, Ru, Rh, Pd, Re, Os, I
r, Pt and Au are preferred. Ions of these metals are 1
Only one kind may be used, and the same kind or different kinds of metal ions may be used.
You may use 2 or more types together. Ions of these metals
Can be introduced into silver halide as metal salt or metal complex.
It 1 x 10 metal ions per mole of silver ^-9Mol ~ 1x
10^-2It is preferably contained in the range of 1 mol.
^-8~ 1 x 10^-FourIs more preferable. Transition metal complex
Or use the complex ion represented by the following general formula.
And are preferred.

In the general formula [ML ₆ ] ^m , M represents a transition metal selected from the elements of groups 6 to 11 of the periodic table, and L represents a ligand. m is 0, -2
Represents-, 3- or 4-. Specific examples of the ligand represented by L include halogen ion (for example, fluorine ion, chlorine ion, bromine ion, iodine ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Each ligand, nitrosyl,
Examples thereof include thionitrosyl, and the like, with preference given to ako, nitrosyl, thionitrosyl and the like. When an aco ligand is present, it preferably occupies one or two of the ligands. Each L may be the same or different.

Compounds providing these metal ions or complex ions are added at the time of silver halide grain formation,
It is preferably incorporated in the silver halide grain, and it may be added at any stage before or after nucleation, growth, physical ripening, or chemical sensitization, which is the stage of preparation of the silver halide grain, but especially nucleation or growth. It is preferable to add at the stage of physical ripening, more preferably at the stage of nucleation and growth, and most preferably at the stage of nucleation. Further, these metals can be uniformly contained in the silver halide grains, and they are disclosed in JP-A-63-29603, JP-A-2-306236 and JP-A-3-1675.
No. 45, No. 4-76534, No. 6-11101.
As described in JP-A-46-46, JP-A-5-273683 and the like, the particles can be contained with a distribution.

These metal compounds can be added after being dissolved in water or a suitable organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). For example, a method of adding an aqueous solution of a metal compound or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, a silver salt solution and a halide solution are added. It can be added by a method of simultaneous mixing of three liquids, which is added as a third aqueous solution when mixing at the same time, or a method of charging a necessary amount of an aqueous solution of a metal compound into a reaction vessel during the formation of silver halide grains. Also, prepare silver halide grains previously doped with metal ions or complex ions,
It can also be added by a method of adding the doped silver halide grains when preparing the silver halide. In particular, an aqueous solution of a metal compound powder or a metal compound and N 2
A method of adding an aqueous solution in which aCl and KCl are dissolved together to a water-soluble halide solution is preferable. When these metal compounds are added to the surface of the particles, a required amount of an aqueous solution of the metal compound is added to the reaction vessel immediately after the particles are formed, during or during physical ripening, or at the time of chemical ripening.

[Spectral Sensitization] The photosensitive silver halide grains can be spectrally sensitized by adsorbing a spectral sensitizing dye.
Examples of spectral sensitizing dyes that can be used include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, and hemioxonol dyes.
For example, JP-A-63-159841 and JP-A-60-1
No. 40335, No. 63-231437, No. 6
3-259651, 63-304242, 63-15245, and U.S. Pat. No. 4,63.
No. 9,414, No. 4,740,455, No. 4,741,966, No. 4,75
The sensitizing dyes described in Nos. 1,175 and 4,835,096 can be used. Further, useful sensitizing dyes are, for example, RD17643 IV-
It is described in the documents described or cited in Item A (Dec. 1978, p. 23) and Item 18431X (Dec. 1978, p. 437). Useful cyanine dyes are, for example, cyanine dyes having a basic nucleus such as thiazoline nucleus, oxazoline nucleus, pyrroline nucleus, pyridine nucleus, oxazole nucleus, thiazole nucleus, selenazole nucleus and imidazole nucleus. Preferred useful merocyanine dyes are acidic nuclei such as thiohydantoin nuclei, rhodanin nuclei, oxazolidinedione nuclei, thiazolindione nuclei, barbituric acid nuclei, thiazolinone nuclei, malononitrile nuclei and pyrazolone nuclei, in addition to the above basic nuclei. Also includes.

[Supersensitizer] The emulsion containing the silver halide grains and the organic silver salt grains used in the photothermographic dry imaging material of the present invention has a spectral sensitizing action by itself together with the sensitizing dye. It is also possible to supersensitize the emulsion by adding a dye or a substance which does not substantially absorb visible light and exhibits a supersensitizing effect to the emulsion. RD1764 is a useful sensitizing dye, a dye or a substance exhibiting supersensitization.
3 (issued in December 1978), page 23, 1V, J, or Japanese Patent Publication Nos. 9-25500, 43-4933, JP-A-59-19032, and 59-192.
No. 242, JP-A-5-341432, etc., the supersensitizer is preferably a heteroaromatic mercapto compound represented by the following general formula [6] or a mercapto derivative compound. .

General formula [6] Ar-SM (wherein M represents a hydrogen atom or an alkali metal atom,
Ar represents a group having an aromatic ring or a condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. ) Examples of the aromatic ring or the condensed aromatic ring in the group having the aromatic ring or the condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atom represented by Ar include, for example, benzimidazole ring and naphthimidazole. Ring, benzthiazole ring, naphthothiazole ring, benzoxazole ring, naphthoxazole ring, benzselenazole ring, benzterrazole ring, imidazole ring,
Oxazole ring, pyrazole ring, triazole ring, triazine ring, pyrimidine ring, pyridazine ring, pyrazine ring,
A pyridine ring, a purine ring, a quinoline ring, and a quinazoline ring are preferable, but other heteroaromatic rings may be used. Further, a mercapto derivative compound which substantially forms the above mercapto compound when contained in a dispersion of an organic acid silver salt and / or a silver halide grain emulsion can also be used.
Further, a preferred example is a mercapto derivative compound represented by the following general formula [7].

General formula [7] Ar-S-S-Ar (In the formula, Ar has the same meaning as Ar in the heteroaromatic mercapto compound represented by the above general formula [6].) The above general formula [ 6] and one or more nitrogen, sulfur, oxygen, selenium, or tellurium atom represented by Ar in the general formula [7], the aromatic ring or the condensed aromatic ring in the group having the aromatic ring or the condensed aromatic ring has It may have a substituent, and these substituents include, for example, a halogen atom (for example, Cl, Br, I), a hydroxy group, an amino group, a carboxyl group, an alkyl group (preferably 1 to 4 groups). An alkyl group having a carbon atom), an alkoxy group (eg, one or more carbon atoms, preferably 1
~ Having 4 carbon atoms). The supersensitizer is preferably used in the emulsion layer containing an organic silver salt and silver halide grains in an amount of 0.001 to 1.0 mol per mol of silver. Particularly preferably, it is 0.01 to 100 mol per mol of silver.
Amounts in the range of 0.5 mol are preferred.

[Non-polyhalogen compound-based print-out preventing agent] For silver salt photothermographic dry imaging materials,
A large amount of photosensitive silver halide, organic silver and a developer which may cause fog or generation of printout silver (printed-out silver) are contained before and after development processing. Therefore, the silver salt photothermographic dry imaging material
It is necessary to use a high degree of fogging prevention and image stabilization technology for maintaining storage stability not only before development but also after development. Conventionally, in order to maintain storage stability and prevent fog and printout silver (printed-out silver) from occurring, aromatic heterocyclic compounds and fog nuclei that suppress the growth and development of fog nuclei are oxidized and eliminated. Although a mercury compound having a function such as mercury acetate has been used, the mercury compound has a problem in its use from the viewpoint of safety / environmental protection. The antifoggant and image stabilizer suitable for the silver salt photothermographic dry imaging material used in the present invention will be described below. A reducing agent is used in the silver salt photothermographic dry imaging material as described later. As these reducing agents, as will be described later, since reducing agents having a proton such as bisphenols and sulfonamidephenols are mainly used, active species capable of extracting these hydrogen are generated. Therefore, it is preferable to contain a compound capable of inactivating the reducing agent. As these compounds, a colorless photo-oxidizable compound capable of generating a free radical as a reactive species upon exposure is preferably used.

These compounds may be any compounds as long as they have these functions, but organic free radicals composed of a plurality of atoms are preferred, and compounds that do not cause any particular harm to the silver salt photothermographic dry imaging material. As long as it is a compound having any structure.
In addition, the compound that generates a free radical is a carbocyclic or heterocyclic compound in order to have stability such that the generated free radical can be contacted for a sufficient time to react with the reducing agent and inactivate. Those having an aromatic group are preferable. Representative examples of these compounds include the following biimidazolyl compounds and iodonium compounds. As the biimidazolyl compound, a biimidazolyl compound represented by the following general formula [1] is preferably used.

[0049]

[Chemical 1] In the general formula [1], R ₁ , R ₂ and R ₃ are an alkyl group (eg, methyl group, ethyl group, hexyl group, etc.), an alkenyl group (eg, vinyl group, allyl group, etc.), an alkoxy group (eg, Methoxy group, ethoxy group, octyloxy group etc.), aryl group (eg phenyl group, naphthyl group, tolyl group etc.), hydroxy group, halogen atom, aryloxy group (eg phenoxy group etc.), alkylthio group (eg, Methylthio group, butylthio group etc.), arylthio group (eg phenylthio group etc.), acyl group (eg acetyl group, propionyl group, butyryl group,
Valeryl group etc.), sulfonyl group (eg methylsulfonyl group, phenylsulfonyl group etc.), acylamino group, sulfonylamino group, acyloxy group (eg acetoxy group, benzoxy group etc.), carboxyl group, cyano group, sulfo group and amino It represents a substituent such as a group. Of these, preferred substituents are aryl groups, alkenyl groups and cyano groups. The above-mentioned biimidazolyl compound can be produced by the production method described in U.S. Pat. No. 3,734,733 and British Patent No. 1,271,177, and its modifications. Further, an iodonium compound represented by the following general formula [2] is preferably used as the iodonium compound.

[0050]

[Chemical 2]

In the general formula [2], R ¹ , R ² and R ³
Is an alkyl group (eg, methyl group, ethyl group, hexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, octyloxy group, etc.), aryl group ( For example, phenyl group, naphthyl group, tolyl group, etc., hydroxy group, halogen atom, aryloxy group (eg phenoxy group etc.), alkylthio group (eg methylthio group, butylthio group etc.), arylthio group (eg phenylthio group) Etc.), acyl group (eg, acetyl group, propionyl group, butyryl group, valeryl group, etc.), sulfonyl group (eg, methylsulfonyl group, phenylsulfonyl group, etc.), acylamino group, sulfonylamino group, acyloxy group (eg, acetoxy group) Groups, benzoxy groups, etc.),
It represents a substituent such as a carboxyl group, a cyano group, a sulfo group and an amino group. Of these, preferred substituents are aryl groups, alkenyl groups and cyano groups. R ⁴ represents a carboxylate group such as acetate, benzoate, trifluoroacetate and O ⁻ . W represents 0 or 1. X ⁻ represents an anionic counterion, and preferable examples thereof include CH ₃ CO ₂ ⁻ , CH ₃ SO ₃ ⁻ and PF ₆ ⁻ . When R ³ is a sulfo group or a carboxyl group,
W is 0 and R ⁴ is O ⁻ . Note that any of R ¹ , R ² and R ³ may be bonded to each other to form a ring. Among the iodonium compounds represented by the above general formula [2], a particularly preferable compound is the following general formula [3]
Is an iodonium compound represented by.

[0052]

[Chemical 3] Here, R ¹ , R ² , R ³ , R ⁴ , X ^−, W and the like represent the same as those in the above general formula [2], and Y represents a carbon atom (−
CH =; benzene ring) or represents a nitrogen atom (-N
=; Pyridine ring).

The above-mentioned iodonium compounds are available in Org. S
yn. , 1961 and Advanced Organi.
c Chemistry by Fieser (Rein
hold, N.M. Y. , 1961) and methods similar thereto. The preferable addition amount of the biimidazolyl compound represented by the general formula [1] and the iodonium compound represented by the general formula [2] is in the range of 0.001 to 0.1 mol / m ² , and more preferably. 0.005-0.05 mol / m
It is in the range of ² . The compound can be contained in any of the constituent layers of the silver salt photothermographic dry imaging material, but is preferably present in the vicinity of the reducing agent.

[Polyhalogen compound-based print-out preventing agent] In the silver salt photothermographic dry imaging material used in the present invention, a compound that inactivates the reducing agent and prevents the reducing agent from reducing the organic silver salt to silver. Is preferably used. As these compounds, those in which the above-mentioned reactive species are not halogen atoms are preferable, but a compound releasing a halogen atom as an active species can also be used in combination with a compound releasing an active species which is not a halogen atom. Many compounds that can release a halogen atom as an active species are known, and by using them in combination, a good effect can be obtained. Examples of the compound that releases an active species that is not a halogen atom include compounds represented by the following general formula [4].

[0055]

[Chemical 4] In the general formula [4], Q represents an aryl group or a heterocyclic group. X ₁ , X ₂ and X ₃ represent a hydrogen atom, a halogen atom, a haloalkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, an aryl group or a heterocyclic group. _At least one of ₁ , X ₂ and X ₃ is a halogen atom. Y is -C (= O) -, - SO- or -SO ₂ - represents a. The aryl group represented by Q may be monocyclic or may be a condensed ring formed with another ring, and is preferably a monocyclic or bicyclic aryl group having 6 to 30 carbon atoms (for example, , Phenyl group, naphthyl group, etc.),
A phenyl group and a naphthyl group are more preferable, and a phenyl group is still more preferable. The heterocyclic group represented by Q is preferably a 3- to 10-membered saturated or unsaturated heterocyclic group containing at least one atom of N, O or S, which may be a monocycle, It may be one that forms a condensed ring with another ring. The heterocyclic group is preferably a 5- to 6-membered unsaturated heterocyclic group which may have a condensed ring, more preferably a 5- to 6-membered aromatic heterocyclic group which may have a condensed ring. Is. More preferably, it is a 5- to 6-membered aromatic heterocyclic group which may have a condensed ring containing a nitrogen atom, and particularly preferably, it may have a condensed ring containing 1 to 4 nitrogen atoms. A good 5- or 6-membered aromatic heterocyclic group.

Examples of the heterocyclic group include imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline. , Pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzthiazole, indolenine, tetrazaindene, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, Thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, syn Phosphorus, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzthiazole, a heterocyclic group derived from tetrazaindene Preferably, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine,
Triazole, triazine, thiadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, benzimidazole, a heterocyclic group derived from benzthiazole, particularly preferably pyridine, thiadiazole,
It is a heterocyclic group derived from quinoline or benzthiazole.

The aryl group and heterocyclic group represented by Q may have a substituent other than --Y--C (X ₁ ) (X ₂ ) (X ₃ ), and preferable substituents are: An alkyl group,
Alkenyl group, aryl group, alkoxy group, aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group,
Aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, sulfonyl group, ureido group, phosphoramide group, halogen atom, cyano group, sulfo group, carboxyl group, nitro group, heterocyclic group and the like, More preferably, alkyl group, aryl group, alkoxy group, aryloxy group, acyl group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, ureido group, phosphoric acid amide Group, a halogen atom, a cyano group, a nitro group, a heterocyclic group, more preferably an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an acylamino group, a sulfonylamino group, a sulfamoyl group,
Carbamoyl group, halogen atom, cyano group, nitro group,
It is a heterocyclic group, particularly preferably an alkyl group, an aryl group, or a halogen atom.

X ₁ , X ₂ and X ₃ are hydrogen atom, halogen atom, haloalkyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, sulfamoyl group, sulfonyl group, aryl group and heterocyclic group. , Preferably a halogen atom, a haloalkyl group,
An acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group and a sulfonyl group are more preferable, a halogen atom and a trihalomethyl group are more preferable, and a halogen atom is particularly preferable. Among the halogen atoms, chlorine atom, bromine atom and iodine atom are preferable, chlorine atom and bromine atom are more preferable, and bromine atom is particularly preferable. At least one of X ₁ , X ₂ and X ₃ is a halogen atom.

Y is -C (= O)-, -SO-, -SO ₂
- represents a, preferably -SO ₂ - is. The addition amount of these active halogen atom-generating compounds in the silver salt photothermographic dry imaging material is preferably within a range in which the increase in printout silver due to the formation of silver halide is not a problem. It is 150% or less, more preferably 100% or less, in terms of the ratio to the compound that does not. The silver salt photothermographic dry imaging material used in the present invention may contain, in addition to the above compounds, compounds conventionally known as antifoggants. It may be a compound that can be produced or a compound having a different antifoggant mechanism. As these compounds,
For example, U.S. Pat. Nos. 3,589,903, 4,546,075, and 4,452,885.
No. 59-57234, US Pat. No. 3,874,946, and US Pat. No. 4,756,999.
Specification, JP-A-9-288328, JP-A-9-
Examples thereof include the compounds described in Japanese Patent No. 90550. Further, other antifoggants include US Pat. No. 5,028,523 and European Patent 600,5.
No. 87, No. 605,981, No. 63
Also included are the compounds disclosed in 1,176.

Next, the reducing agent used in the silver salt photothermographic dry imaging material of the present invention will be described. Examples of suitable reducing agents for these reducing agents are described in US Pat. No. 3,770,
448, 3,773,512, 3,593,863, RD17029 and 2
It is described in 9963 and can be appropriately selected and used from known reducing agents, but when an aliphatic carboxylic acid silver salt is used as the organic silver salt, two or more phenol groups are alkylene. Groups or polyphenols linked by sulfur, in particular an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a t-butyl group, at least one of the positions adjacent to the hydroxy-substituted position of the phenol group,
2 of a phenol group substituted with a cyclohexyl group) or an acyl group (eg, acetyl group, propionyl group, etc.)
Bisphenols in which one or more are linked by an alkylene group or sulfur are preferred. More preferable examples of these preferable bisphenols include compounds represented by the following general formula (A).

[0061]

[Chemical 5] In the general formula (A), R is a hydrogen atom or a carbon atom number 1 to
Represents an alkyl group of 10 (for example, isopropyl group, butyl group, 2,4,4-trimethylpentyl group), R ′
And R ″ represent an alkyl group having 1 to 8 carbon atoms (eg, methyl group, ethyl group, t-butyl group).

In addition, US Pat. No. 3,589,903, US Pat. No. 4,021,249, British Patent No. 1,486,148, JP-A-51-51933.
No. 50-36110, No. 50-1160.
No. 23, No. 52-84727, and Japanese Patent Publication No. 51-
A polyphenol compound described in Japanese Patent No. 35727,
Bisnaphthols described in U.S. Pat. No. 3,672,904, such as 2,2'-dihydroxy-
1,1'-binaphthyl, 6,6'-dibromo-2,2 '
-Dihydroxy-1,1'-binaphthyl and the like, as well as sulfonamide phenols or sulfonamide naphthols such as those described in U.S. Pat. No. 3,801,321, such as 4-benzenesulfonamidophenol, 2 -Benzenesulfonamide phenol, 2,
Mention may also be made of 6-dichloro-4-benzenesulfonamide phenol, 4-benzenesulfonamide naphthol and the like. Japanese Patent Application No. 200 other than the compounds listed above
The compounds described in the specification of 1-21659 are also included. The amount of the reducing agent used in the photothermographic dry imaging material of the present invention varies depending on the type of the organic silver salt, the reducing agent and other additives, but generally, the organic silver salt 1
It is used in the range of 0.01 to 10 mol per mol, and more preferably in the range of 0.1 to 3 mol. Further, the reducing agents described above may be used alone or in combination of two or more kinds. When a reducing agent is added to and mixed with a photosensitive emulsion solution consisting of photosensitive silver halide and organic silver salt particles and a solvent, the reducing agent is added immediately before coating to shorten the stagnation time in the coating solution and reduce fluctuations in photographic performance. In some cases, it can be preferable. Further, the reducing agent should be used as an auxiliary agent in combination with a compound capable of forming a hydrogen bond with hydrogen of the hydroxyl group of the reducing agent, such as triphenylphosphine oxide described in European Patent No. 1096310. Is also preferable.

[Silver Saving Agent] A silver saving agent can be used in the silver salt photothermographic dry imaging material used in the present invention. The silver saving agent refers to a compound capable of reducing the amount of silver necessary to obtain a constant silver image density. Although various mechanisms of action of this reducing function have been considered, compounds having a function of improving the covering power of developed silver are preferable. Here, the covering power of developed silver means the optical density per unit amount of silver. As a silver saving agent, Japanese Patent Application No. 2000-19106.
The compounds described in Japanese Patent No. 2 and Japanese Patent Application No. 2001-192698 are preferred examples.

Binders Suitable binders for use in photothermographic dry imaging materials are transparent or translucent, generally colorless, natural polymers synthetic resins, polymers and copolymers, and other film-forming media such as gelatin. , Gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), Poly (methacrylic acid), copoly (styrene-
Maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (for example, poly (vinyl formal) and poly (vinyl butyral)), poly (ester) s,
There are poly (urethane) s, phenoxy resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, poly (amides). The binder used may be hydrophilic or non-hydrophilic. Preferred binders for use in the photosensitive layer of photothermographic dry imaging materials are polyvinyl acetals, and particularly preferred binders are polyvinyl butyral. Further, for the non-light-sensitive layer such as the overcoat layer and the undercoat layer, particularly the protective layer and the backcoat layer, cellulose esters having a higher softening temperature, particularly triacetyl cellulose,
Polymers such as cellulose acetate butyrate are preferred. The above binders may be used in combination of two or more, if necessary. Such a binder is used in an effective range to function as a binder. The effective range can be easily determined by those skilled in the art. For example, as an index when at least the organic silver salt is retained in the photosensitive layer, the ratio of the binder to the organic silver salt is 1
A range of 5: 1 to 1: 2, particularly 8: 1 to 1: 1 is preferable. The amount of binder in the photosensitive layer is 1.5 to 6 g / m.
It is preferably ² . More preferably 1.7 to 5 g
/ M ² . If it is less than 1.5 g / m ² , the density of the unexposed area may increase significantly and it may not be usable.

(Organic Gelling Agent) The photosensitive layer may contain an organic gelling agent. The term "organic gelling agent" as used herein means, for example, a function of giving a yield value to the system by adding it to an organic liquid such as polyhydric alcohols and eliminating or lowering the fluidity of the system. Refers to a compound having

(Aqueous coating) When the coating liquid for forming the photosensitive layer of the salt photothermographic dry imaging material contains an aqueous dispersed polymer latex, 50% by mass or more of all binders in the coating liquid is an aqueous dispersed polymer. It is preferably latex. The “polymer latex” according to the present invention is a dispersion of water-insoluble hydrophobic polymer as fine particles in a water-soluble dispersion medium. As the dispersed state, the polymer is emulsified in the dispersion medium, emulsion-polymerized, micelle-dispersed, or polymer molecules having a partially hydrophilic structure and molecular chains themselves being molecularly dispersed. And so on. The average particle size of the dispersed particles is 1 to 50,000 nm, more preferably 5 to 100 nm.
The range of about 0 nm is preferable. The particle size distribution of the dispersed particles is not particularly limited, and it may have a wide particle size distribution or a monodisperse particle size distribution. As the polymer latex, so-called core / shell type latex may be used in addition to the usual polymer latex having a uniform structure. In this case, it may be preferable that the core and the shell have different glass transition temperatures. Minimum film forming temperature of polymer latex (M
FT) is preferably −30 to 90 ° C., more preferably 0 to 70 ° C. Further, a film forming auxiliary may be added to control the minimum film forming temperature.
The film-forming aid is also called a plasticizer, and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. "It is described in.

Examples of the polymer used for the polymer latex include acrylic resin, vinyl acetate resin, polyester resin, polyurethane resin, rubber resin, vinyl chloride resin, vinylidene chloride resin, polyolefin resin, and copolymers thereof. . The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer obtained by polymerizing a single monomer,
It may be a copolymer in which two or more kinds of monomers are polymerized. In the case of a copolymer, it may be a random copolymer or a block copolymer. The number average molecular weight of the polymer is 5
000 to 1,000,000, preferably 10,000 to 10
About 0000 is preferable. If the molecular weight is too small, the mechanical strength of the photosensitive layer is insufficient, and if it is too large, the film-forming property is poor, which is not preferable. 25 ° C for polymer latex,
The equilibrium water content at 60% RH is preferably 0.01 to 2% by mass or less, and more preferably 0.01 to 1% by mass.
belongs to. For the definition and measurement method of equilibrium water content,
For example, "Polymer Engineering Course 14, Polymer Material Testing Method (edited by The Polymer Society of Japan, Jijijinkan)" can be referred to.

Specific examples of the polymer latex include, for example, latex of methyl methacrylate / ethyl acrylate / methacrylic acid copolymer, latex of methyl methacrylate / 2-ethylhexyl acrylate / styrene / acrylic acid copolymer, latex of styrene / butadiene / acrylic acid copolymer. , Latex of styrene / butadiene / divinylbenzene / methacrylic acid copolymer, latex of methyl methacrylate / vinyl chloride / acrylic acid copolymer, vinylidene chloride / ethyl acrylate / acrylonitrile / methacrylic acid copolymer latex, and the like. These polymers may be used alone, or may be used by blending two or more kinds as necessary. The polymer type of the polymer latex preferably contains a carboxylic acid component such as an acrylate or methacrylate component in an amount of about 0.1 to 10% by mass. Furthermore, if necessary, hydrophilic polymers such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and hydroxypropyl methyl cellulose may be added in the range of 50% by mass or less of the total binder. The addition amount of these hydrophilic polymers is preferably 30% by mass or less of the total binder of the photosensitive layer.

In the preparation of the coating liquid for forming the photosensitive layer, the organic silver salt and the aqueous dispersed polymer latex may be added in any order, or may be added at the same time, but preferably, The polymer latex is later. Further, it is preferable that an organic silver salt and further a reducing agent are mixed before the addition of the polymer latex. Further, after mixing the organic silver salt and the polymer latex, if the temperature for aging is too low, the coating surface state will be impaired, and if it is too high, the fog will increase.
It is preferable that the above time is elapsed. Furthermore, 35 ℃ ~
It is preferable to age at 60 ° C, and particularly 35 ° C to 5 ° C.
It is preferable to age at 5 ° C. In order to maintain the temperature in this way, it is sufficient to keep the temperature of the coating solution preparation tank or the like. The coating of the coating solution for forming the photosensitive layer is preferably carried out by mixing the organic silver salt and the polymer latex dispersed in water for 30 minutes to 24 hours, more preferably 60 minutes after mixing. It is allowed to stand for 12 hours, and it is particularly preferable to use the coating solution after 120 minutes to 10 hours. Here, “after mixing” means after the organic silver salt and the polymer latex dispersed in water are added, and the additive materials are uniformly dispersed.

[Crosslinking Agent] It is known that when a crosslinking agent is used for the above binder, film formation is improved and development unevenness is reduced, but fog is suppressed during storage and printout silver is developed after development. It also has the effect of suppressing generation.
As the cross-linking agent, various cross-linking agents conventionally used for photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinyl sulfone-based, sulfone described in JP-A No. 50-96216. Acid ester type,
Although an acryloyl-based, carbodiimide-based, or silane compound-based crosslinking agent can be used, the following isocyanate-based compounds, silane compounds, epoxy compounds, or acid anhydrides are preferable. An isocyanate type crosslinking agent and a thioisocyanate type crosslinking agent represented by the following general formula [8], which are one of the preferable examples, will be described below.

General formula [8] X = C = NL- (N = C = X) v In the formula, v is 1 or 2, and L may be an alkylene, alkenylene, arylene group or alkylarylene group. It is a divalent or trivalent linking group, and X is an oxygen or sulfur atom. In the compound represented by the above general formula [8], the aryl ring of the arylene group may have a substituent. Examples of preferred substituents are halogen atoms (eg, bromine atom or chlorine atom), hydroxy group, amino group, carboxyl group, alkyl group and alkoxy group.

The above-mentioned isocyanate-based cross-linking agent is an isocyanate having at least two isocyanate groups and an adduct thereof (adduct), and more specifically, aliphatic diisocyanates and fats having a cyclic group. Group diisocyanates, benzene diisocyanates, naphthalene diisocyanates, biphenyl isocyanates, diphenylmethane diisocyanates, triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates, such as isocyanates and divalent or Three
Examples thereof include adducts with valent polyalcohols. Specific examples include pages 1 to 10 of JP-A-56-5535.
The isocyanate compounds described on page 2 can be mentioned, and these can be used. The isocyanate-polyalcohol adduct has particularly high ability to improve interlayer adhesion and prevent layer peeling, image misalignment, and bubble generation. Such isocyanates may be placed on any part of the photothermographic material. For example, in a support (particularly when the support is paper, it can be included in the size composition), a photosensitive layer of the support such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer and an undercoat layer. It can be added to any layer on the side, and can be added to one layer or two or more layers among these layers. As the thioisocyanate-based cross-linking agent that can be used in the present invention, compounds having a thioisocyanate structure corresponding to the above isocyanates are also useful. The amount of the above crosslinking agent used in the present invention is in the range of 0.001 to 2 mol, preferably 0.005 to 0.5 mol, per 1 mol of silver. As described above, the isocyanate compound and the thioisocyanate compound used are preferably compounds that function as the above-mentioned cross-linking agent.
In v, 0 is obtained, that is, a compound having only one functional group concerned may be obtained.

Examples of the silane compound that can be used as the crosslinking agent include the compounds disclosed in Japanese Patent Application No. 12-077904.

The epoxy-based cross-linking agent may be any epoxy compound having one or more epoxy groups.
There is no restriction on the molecular weight and others. The epoxy group is preferably contained in the molecule as a glycidyl group via an ether bond or an imino bond. The epoxy compound may be a monomer, an oligomer, a polymer, or the like, and the number of epoxy groups present in the molecule is usually about 1 to 10, preferably 2 to 4. When the epoxy compound is a polymer, it may be either a homopolymer or a copolymer, and the particularly preferable range of the number average molecular weight Mn thereof is about 2000 to 20000. The epoxy compound can be added to any layer on the photosensitive layer side of the support such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. It can be added. In addition, in addition, it can be added to any layer on the side opposite to the photosensitive layer of the support. Any layer may be used in the silver salt photothermographic dry imaging material having photosensitive layers on both sides.

The acid anhydride that can be used as the crosslinking agent is a compound having at least one acid anhydride group represented by the following structural formula. The -CO-O-CO-acid anhydride may have one or more such acid anhydride groups,
The number of acid anhydride groups, the molecular weight, etc. are not limited, but the compound represented by the general formula [B] is preferable.

[0076]

[Chemical 6] In the general formula [B], Z represents an atomic group necessary for forming a monocyclic or polycyclic system. The ring formed by Z may be unsubstituted or substituted. Examples of the substituent include an alkyl group (eg, methyl group, ethyl group, hexyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, octyloxy group, etc.), aryl group (eg, phenyl group, naphthyl group). , Tolyl group, etc.), hydroxy group,
Aryloxy group (eg, phenoxy group, etc.), alkylthio group (eg, methylthio group, butylthio group, etc.),
Arylthio group (eg, phenylthio group), acyl group (eg, acetyl group, propionyl group, butyryl group, etc.), sulfonyl group (eg, methylsulfonyl group, phenylsulfonyl group, etc.), acylamino group, sulfonylamino group, acyloxy group (For example, acetoxy group, benzoxy group, etc.), carboxyl group, cyano group, sulfo group, amino group are included. The substituent preferably does not contain a halogen atom. These acid anhydrides are 1
Only one species may be used or two or more species may be used in combination. The addition amount is not particularly limited, but 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol /
The range of m ² is preferable, and more preferably 1 × 10 ⁻⁵ to 1
It is in the range of × 10 ^-3 mol / m ² . In the present invention, the acid anhydride can be added to any layer on the photosensitive layer side of the support such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer and an undercoat layer. One of these layers or It can be added in two or more layers. Also, it may be added to the same layer as the epoxy compound. The photothermographic dry imaging material forms a photographic image by heat development processing, and it adjusts the color tone of the silver source (organic silver salt), the photosensitive silver halide particles, the reducing agent, and silver if necessary. It is preferable that the above-mentioned toning agent is contained in a state of being normally dispersed in an (organic) binder matrix.

[Toning Agent] An example of a toning agent suitable for use is RD17029, US Pat. No. 4,123,282.
No. 3,994,732 and No. 3,994,732
846,136 and 4,021,249
The following are disclosed in the specification.
Imides (eg, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide, etc.); mercaptans (eg, 3-mercapto-1,2,4-triazole, etc.); phthalazinone derivatives or metals of these derivatives Salts (for example, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione);
A combination of phthalazine and phthalic acids (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid); phthalazine and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o- Phenylenic acid derivatives and their anhydrides (for example,
Phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic acid anhydride, and the like) and a combination thereof with at least one compound.
A particularly preferable toning agent is phthalazinone or a combination of phthalazine and phthalic acids or phthalic anhydrides. Regarding the color tone of an output image for medical diagnosis, it has been conventionally said that a cold image tone is easier for a reader of an X-ray photograph to obtain a more accurate diagnostic observation result of a recorded image. Here, the cold image tone is a pure black tone or a bluish black tone in which the black image is bluish, and the warm image tone is a black tone in which the black image is brownish. Say.

The terms "more cool" and "more warm" with respect to color tones refer to the minimum density Dmin and the optical density D = 1.0.
It is obtained by the hue angle hab. Hue angle hab
Is a color space recommended by the International Commission on Illumination (CIE) in 1976, which has a perceptually nearly uniform rate, and uses the color coordinates a ^* , b ^* of the L ^* a ^* b ^* color space according to the following formula. Ask. hab = tan ⁻¹ (b ^* / a ^* ) In the present invention, the preferable range of hab is 180 ° <h.
ab <270 °, more preferably 200 ° <ha
b <270 °, most preferably 220 ° <hab <26
It is 0 °. In the present invention, the preferable range of hab is 180 ° <hab <270 °, more preferably 200 ° <hab <270 °, and most preferably 220 °.
<Hab <260 °.

[Mat agent] The surface layer of the non-photosensitive layer provided on the side opposite to the photosensitive layer of the photothermographic dry imaging material and the support is sandwiched, and the surface layer of the non-photosensitive layer is handled before development and the image is prevented from being scratched after thermal development. Therefore, it is preferable to contain a matting agent, and it is preferable to contain 0.1 to 30 mass% of the binder. The material of the matting agent may be either organic or inorganic. For example, silica, which is an inorganic substance, described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, and British Patent No. 1,173,181. Alkaline earth metals such as those described in Japanese Patents, carbonates such as cadmium and zinc, and organic substances such as starch described in U.S. Pat. No. 2,322,037, Belgian Patent No. 625,451, Starch derivatives described in British Patent No. 981,198, polyvinyl alcohol described in Japanese Patent Publication No. 44-3643, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, etc., Polyacrylonitrile described in US Pat. No. 3,079,257 and polycarbonate described in US Pat. It can be used as bets agent. The matting agent has an average particle size of 0.5 μm
It is preferably 10 μm, more preferably 1.0
μm to 8.0 μm. The coefficient of variation of particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30%.
It is a matting agent whose content is less than or equal to%. Here, the variation coefficient of the particle size distribution is a value represented by the following formula. Coefficient of variation of particle size distribution (%) = [(standard deviation of particle size) / (average value of particle size)] × 100 The matting agent may be added by a method of previously dispersing in a coating liquid and coating. Of course, after applying the coating solution, the matting agent may be sprayed before the drying is completed. When adding a plurality of types of matting agents, both methods may be used in combination.

As the material of the support used for the photothermographic dry imaging material, various polymeric materials, glass, wool cloth, cotton cloth, paper, metal (for example, aluminum, etc.)
However, in consideration of handling as an information recording material, a material that can be processed into a flexible sheet or roll is preferable. Therefore, as the support, a plastic film (for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film,
A polyamide film, a polyimide film, a cellulose triacetate film, a polycarbonate film or the like) is preferable, and a biaxially stretched polyethylene terephthalate film is particularly preferable in the present invention. The thickness of the support is preferably 50 to 300 μm, and 70 to
180 μm is preferable.

[Antistatic Agent] The photothermographic dry imaging material may contain a conductive compound such as a metal oxide and / or a conductive polymer in the constituent layers in order to improve the charging property. These may be contained in any layer, but are preferably contained in the undercoat layer, the backing layer, the layer between the photosensitive layer and the undercoat, and the like. As the conductive compound, the conductive compounds described in US Pat. No. 5,244,773, columns 14 to 20, are preferably used.

[Layer Structure] The photothermographic dry imaging material has at least one photosensitive layer on a support.
Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer.
For example, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and sticking between the photothermographic dry imaging materials or between the photothermographic dry imaging material and the roll may be performed on the opposite surface of the support. In order to prevent this, it is preferable to provide a back coat layer. As the binder used in these protective layer and back coat layer, a glass transition point is higher than that in the heat developing layer, and scratches and polymers that are less likely to be deformed, for example, polymers such as cellulose acetate and cellulose acetate butyrate are mentioned above. Selected from binders. Two or more photosensitive layers may be provided on one side of the support or one or more photosensitive layers may be provided on both sides of the support in order to adjust gradation.

[Dye] In the photothermographic dry imaging material, in order to control the amount or wavelength distribution of light passing through the photosensitive layer, a filter layer is formed on the same side as or opposite to the photosensitive layer, or the photosensitive layer is formed. It is preferable to include a dye or a pigment. As the dye, a known compound that absorbs light in various wavelength regions depending on the color sensitivity of the photothermographic dry imaging material can be used. For example, when the photothermographic dry imaging material is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in Japanese Patent Application No. 11-255557 (hereinafter referred to as thiopyrylium squarylium). And a squarylium dye having a pyrylium nucleus (hereinafter sometimes referred to as pyrylium squarylium dye) (hereinafter, these are collectively referred to as croconium dye). It is also preferable to use a nickel dye or a pyrylium croconium dye. The squarylium dye is a dye having 1-cyclobutene-2-hydroxy-4-one in its molecular structure, and the croconium dye is 1-cyclopentene-2-hydroxy-4,5-dione in its molecular structure. It is a dye that has. Here, the hydroxy group may be dissociated. As the dye, the compounds described in JP-A 8-201959 are also preferable.

[Coating Technique] The silver salt photothermographic dry imaging material is prepared by dissolving or dispersing the materials of the above-mentioned constituent layers in a solvent to prepare a coating solution, and applying a plurality of coating solutions at the same time, and then heat treatment. It is preferably formed by carrying out. Here, "multi-layer coating at the same time" means that a coating liquid for each constituent layer (eg, photosensitive layer, protective layer) is prepared, and when the coating liquid is applied to a support, coating and drying are repeated for each layer. Rather, it means that each constituent layer is formed in a state in which the steps of simultaneously performing multi-layer coating and drying can be performed at the same time. Simultaneous multilayer coating means that the upper layer is provided before the residual amount of all the solvents in the lower layer becomes 70% by mass or less.

There is no particular limitation on the method for applying a plurality of layers of each constituent layer at the same time, and examples thereof include bar coater method, curtain coating method, dipping method, air knife method, hopper coating method,
A known method such as an extrusion coating method can be used. Of these, the pre-weighing type coating method called the extrusion coating method is more preferable. Unlike the slide coating method, the extrusion coating method does not volatilize on the slide surface, so precise coating,
Suitable for organic solvent coating. This coating method has been described on the side having the photosensitive layer, but when the back coat layer is provided,
The same applies to the case of applying with subbing. In the present invention, the coated silver amount is preferably selected in an appropriate amount according to the purpose of use of the silver salt photothermographic dry imaging material, but in the case of obtaining a medical image, 0.6 g / m ² or more 2.5 g / m ² or less.
Further, it is preferably 0.8 g / m ² or more and 1.5 g / m ² or less. Of the coated silver amount, those derived from silver halide preferably account for 2% to 18% of the total silver amount, and more preferably 5% to 15%. Also, 0.01
The coating density when using silver halide grains having a size of μm or more (equivalent sphere equivalent size) is 1 × 10 ¹⁴ particles / m ² or more 1 × 10 ^18.
The number / m ² or less is preferable. Further, it is preferably 1 × 10 ¹⁵ pieces / m ² or more and 1 × 10 ¹⁷ pieces / m ² or less. When the non-photosensitive long-chain aliphatic carboxylic acid silver is used, the coating density of the non-photosensitive long-chain aliphatic carboxylic acid silver is 0.01 μm or more (corresponding sphere equivalent particle size) 1 x per piece
10 ^-17 g or more and 1 x 10 ^-15 g or less, and further 1 x 10 ^-1
It is preferably ⁶ g or more and 1 × 10 ⁻¹⁴ g or less. When coated under the conditions within the above range, it is preferable from the viewpoint of the optical maximum density of the silver image per fixed amount of coated silver, that is, the silver coating amount (covering power) and the color tone of the silver image. The result is obtained.

[Development Conditions] The development conditions of the silver salt photothermographic dry imaging material vary depending on the equipment, device or means used, but typically, the photothermographic dry imaging material exposed imagewise is heated. By doing. The latent image obtained after exposure has a moderately high temperature (eg,
It can be developed by heating the photothermographic material at about 80-200 ° C, preferably about 100-200 ° C, for a sufficient period of time (generally about 1 second to about 2 minutes). When the heating temperature is 80 ° C or lower, sufficient image density cannot be obtained in a short time.
Also, at 200 ° C or higher, the binder melts and is transferred to the roller, so that not only the image itself but also the transportability,
It also adversely affects the developing machine. By heating, a silver image is generated by a redox reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent. This reaction process can proceed without supplying any processing liquid such as water from the outside. As a device, device or means for heating, a typical heating means such as a hot plate, iron, hot roller, heat generator using carbon or white titanium can be used. In the case of a silver salt photothermographic dry imaging material provided with a protective layer, the surface having the protective layer is heated by contacting it with a heating means in order to perform uniform heating, and also in terms of thermal efficiency and workability. It is preferable that the surface is brought into contact with a heat roller, and the surface is conveyed, heated, and developed. The silver salt photothermographic dry imaging material has a heating temperature of 123 ° C. and a development time of 13.5.
The image obtained by heat development in seconds is a characteristic curve shown on the orthogonal coordinates where the unit lengths of the diffusion density (Y axis) and the common logarithmic exposure amount (X axis) are the same, and the optical density of the diffused light is 0. Two
It is preferable that the average gradation of 5 to 2.5 is 2.0 to 4.0. When the gradation is adjusted by adjusting the sensitivity of the photosensitive silver halide grains, the amount of coated silver, the layer structure, etc., it becomes possible to obtain an image with high diagnostic recognition. [Exposure] In the present invention, the silver salt photographic light-sensitive material is exposed to fluorescence emitted by the radiation image conversion panel of the present invention upon irradiation with radiation energy. It is desirable that the color sensitivity of the silver salt photographic light-sensitive material used is appropriate for the wavelength of fluorescence emitted by the radiation image conversion panel.

[Solvent Content] The silver salt photothermographic dry imaging material contains 5 to 1000 mg of a solvent at the time of development.
It is preferably contained in the range of / m ² . More preferably, it is in the range of 100 to 500 mg. By doing so, high sensitivity, low fog, and maximum density can be obtained. Examples of the solvent that can be used include ketones such as acetone, methyl ethyl ketone and isophorone, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol and benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol. , Glycols such as hexylene glycol, ether alcohols such as ethylene glycol monomethyl ether and diethylene glycol monoethyl ether, ethers such as isopropyl ether, esters such as ethyl acetate and butyl acetate, chlorides such as methylene chloride and dichlorobenzene. Examples include substances and hydrocarbons.
In addition, water, formamide, dimethylformamide, toluidine, tetrahydrofuran, acetic acid and the like can be used. However, the solvent that can be used is not limited to these. These solvents can be used alone or in combination of several kinds.
The solvent contained in the silver salt photothermographic dry imaging material can be contained by changing the temperature conditions in the drying step after the coating step. The content can be adjusted by changing the conditions. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

[0088]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Example 1 (Preparation of Phosphor Particles Z1 to Z3) Yttrium Y nitrate, Gadolinium Gd nitrate, Europium Eu in water
The above nitrates were mixed so that the mass ratio of yttrium Y, gadolinium Gd, and europium Eu would be the ratios shown in Table 1, and the dissolved aqueous solution was heated at 85 ° C. for 1.0 hour, and hydrogen peroxide (30%) 1 An aqueous solution containing 0.5 ml of urea and 500 g of urea was added and further heated to deposit spherical particles of a basic carbonate of a rare earth element. Then, the precipitated basic carbonate of mixed rare earth element was subjected to solid-liquid separation to obtain spherical particles of phosphor of basic carbonate of rare earth element. The spherical particles of the basic carbonate are further baked at 750 ° C. in an oxidizing atmosphere,
Spherical fine particle phosphors Z1 to Z3 made of rare earth oxides were obtained. Table 1 also shows the crystallite size, average particle size and fluorescence wavelength of the obtained spherical fine particle phosphors Z1 to Z3.

[0089]

[Table 1]

(Production of Radiation Image Conversion Panels P1 to P3) —Preparation of Coating Liquid for Phosphor Layer Formation— 200 g of spherical fine particle phosphor Z1 and binder [polyurethane type thermoplastic elastomer demolac TPKL-5-2.
625 (solid content 40%) (Sumitomo Bayer Urethane Co., Ltd.)] 20 g, nitrocellulose (nitrification degree 11.5
%) 2 g of a methyl ethyl ketone solvent was added and dispersed by a propeller-type mixer to prepare a coating solution for forming a phosphor layer having a viscosity of 25 ps (25 ° C.) (binder / phosphor ratio = 1/2).
2). —Preparation of Coating Liquid for Forming Undercoat Layer— 90 g of a soft acrylic resin (solid content) and 60 g of nitrocellulose were dispersed and mixed by adding methyl ethyl ketone to prepare a dispersion liquid having a viscosity of 3 to 6 ps (25 ° C.). —Preparation of Radiation Image Conversion Panels P1 to P3— A polyethylene terephthalate base (support) having a thickness of 220 μm in which titanium dioxide is kneaded is placed horizontally on a glass plate, and the coating solution for forming the undercoat layer is prepared using a doctor blade. After uniformly coating on the support, 25 ℃ to 100
The coating film was dried by gradually raising the temperature to 0 ° C. to form an undercoat layer on the support. The thickness of the coating film was 15 μm. Onto this, the above-mentioned phosphor layer forming coating solution was uniformly applied and dried to a thickness of 150 μm using a doctor blade, and then compressed. The compression was performed using a calender roll at a pressure of 300 Kgw / cm ² and a temperature of 80 ° C. After this compression, a transparent protective layer having a thickness of 3 μm was formed by the method described in Example 1 of JP-A-6-75097.
A radiation image conversion panel P1 was produced. Spherical fine particle phosphor Z
Radiation image conversion panels P2 and P3 were prepared in the same manner as the radiation image conversion panel P1 except that spherical fine particle phosphors Z2 and Z3 were used instead of No. 1.

(Preparation of Photosensitive Material F100) <Preparation of Substrate for Photographic Substrate> Commercially available biaxially stretched and heat-fixed with an optical density of 175 μm and a density of 0.170 (Konica Corporation densitometer PDA-65 was used. Measured with blue) and subjected to corona discharge treatment of 8 W / m ² · min on both sides of the polyethylene terephthalate (PET) film
The following subbing coating solution a-1 was dried on one surface to a dry film thickness of 0.8 μm.
And dried to form an undercoat layer A-1, and an undercoat coating solution b-1 shown below is applied to the opposite surface to give a dry film thickness of 0.
It was coated and dried to have a thickness of 8 μm to form an undercoat layer B-1. << Subbing coating liquid a-1 >> Copolymer latex liquid of butyl acrylate (30 mass%), t-butyl acrylate (20 mass%), styrene (25 mass%), 2-hydroxyethyl acrylate (25 mass%) (Solid content: 30%) 270 g C-1 0.6 g Hexamethylene-1,6-bis (ethyleneurea) 0.8 g Finish with water to 1 L << Undercoating liquid b-1 >> Butyl acrylate (40% by mass), Copolymer latex liquid of styrene (20% by mass) and glycidyl acrylate (40% by mass) (solid content 30%) 270 g C-1 0.6 g hexamethylene-1,6-bis (ethyleneurea) 0.8 g With water After finishing to 1 L, on the upper surface of the undercoat layer A-1 and the undercoat layer B-1,
A corona discharge of 8 W / m ² · min was applied, and the following undercoating upper layer coating solution a-2 was applied on the undercoating layer A-1 to a dry film thickness of 0.1 μm and dried to obtain the undercoating upper layer A. -2 is formed on the undercoat layer B-1, and the following undercoating upper layer coating solution b-2 is applied to have a dry film thickness of 0.8 μm and dried to have an antistatic function. -2 was formed.

<< Undercoating Upper Layer Coating Liquid a-2 >> Gelatin 0.4 g / m ² Mass 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 L << Undercoating upper layer coating liquid b-2 >> C-4 60 g Latex liquid containing C-5 (solid content 20%) 80 g Ammonium sulfate 0.5 g C-6 12 g Polyethylene glycol (weight average) Molecular weight 600) 6g Make up to 1L with water

[0093]

[Chemical 7]

[0094]

[Chemical 8]

<Coating on Back Side> While stirring 830 g of methyl ethyl ketone (MEK), cellulose acetate butyrate (Eastman Chemical Company,
CAB381-20) 84.2 g and polyester resin (Bostic, VitelPE2200B) 4.
5 g was added and dissolved. Then, to the resulting solution, 0.3
0 g of Infrared Dye-1 was added and methanol 43.
4.5 g of fluorinated activator (Surflon KH40, Asahi Glass Co., Ltd.) and 2.3 g of fluorinated activator (Megafag F120K, Dainippon Ink and Chemicals, Inc.) dissolved in 2 g were added and sufficiently stirred until dissolved. Finally, silica dispersed in methyl ethyl ketone at a concentration of 1 mass% by a dissolver type homogenizer (WR Grace, Syloid 64).
X6000) was added and stirred to prepare a coating liquid for the back side.

[0096]

[Chemical 9] The coating liquid for the back surface side thus prepared was applied onto the undercoat upper layer by an extrusion coater so that the dry film thickness was 3.5 μm, and dried. Drying temperature is 100
The drying was carried out for 5 minutes using a dry air of 10 ° C and an open-air temperature of 10 ° C.

<Coating on Photosensitive Layer Side><< Preparation of Photosensitive Silver Halide Emulsion A >> Solution (A1) Phenylcarbamoylated gelatin 88.3 g Compound (A) (10% aqueous methanol solution) 10 ml Potassium bromide 0.32 g Water Solution (B1) 0.67 mol / L aqueous solution of silver nitrate 2635 ml solution (C1) potassium bromide 51.55 g potassium iodide 1.47 g solution to make 660 ml with water (D1) potassium bromide 154.9 g potassium iodide 4.41 g Iridium chloride (1% solution) 0.93 ml Finish with water to 1982 ml Solution (E1) 0.4 mol / L potassium bromide aqueous solution Silver potential control amount solution (F1) potassium hydroxide 0.71 g Water to 20 ml Finishing solution (G1) 56% acetic acid aqueous solution 18.0 ml solution (H1 Compounds finish 151ml anhydrous sodium carbonate 1.72g water _{(A): HO (CH 2} CH 2 O) n - (CH (CH
_{3) CH 2 O) 17 -} (CH 2 CH 2 O) m H (m + n = 5~
7)

Japanese Patent Publication No. 58-58288, 58-58
In the solution (A1), a quarter of the solution (B1) and the total amount of the solution (C1) were controlled at a temperature of 45 ° C. and pAg of 8.09 by using the mixing stirrer disclosed in Japanese Patent No. 58289, and then 4 minutes by the simultaneous mixing method. It took 45 seconds to add and perform nucleation. After 1 minute, the total amount of solution (F1) was added. Adjustment of pAg was appropriately performed using (E1). After 6 minutes, 3/4 amount of the solution (B1) and the whole amount of the solution (D1) were heated to a temperature of 4
While controlling at 5 ° C. and pAg of 8.09, the mixture was added by the simultaneous mixing method over 14 minutes and 15 seconds. After stirring for 5 minutes, 4
The temperature was lowered to 0 ° C., the entire amount of the solution (G1) was added, and the silver halide emulsion was precipitated. The supernatant was removed, leaving 2000 ml of the sedimented portion, 10 liters of water was added, and after stirring, the silver halide emulsion was sedimented again. Settling part 1500m
The supernatant liquid was removed, leaving 1 l, and 10 liters of water was further added. After stirring, the silver halide emulsion was allowed to settle. After removing the supernatant liquid, leaving 1500 ml of the sedimented portion, the solution (H1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8 and water was added so that the amount was 1161 g per mol of silver, whereby a silver halide emulsion was obtained. This emulsion has an average grain size of 0.058
The particles were monodisperse cubic silver iodobromide grains having a particle size distribution variation coefficient of 12% and a (100) plane ratio of 92%. Next, 240 ml of sulfur sensitizer S-5 (0.5% methanol solution) was added to the emulsion, and 2/2 of this sensitizer was added.
0 mol of gold sensitizer Au-5 (0.5% ethanol solution) was added, and the mixture was stirred at 55 ° C. for 120 minutes for chemical sensitization to obtain a photosensitive silver halide emulsion A.

<< Preparation of Powdered Organic Silver Salt A >> 130.8 g of behenic acid and 67.7 of arachidic acid in 4720 ml of pure water.
g, stearic acid 43.6 g, and palmitic acid 2.3 g were dissolved at 80 ° C. Next, 540.2 ml of a 1.5 M sodium hydroxide aqueous solution was added, 6.9 ml of concentrated nitric acid was added, and then the mixture was cooled to 55 ° C. to obtain a fatty acid sodium solution. While keeping the temperature of the fatty acid sodium solution at 55 ° C., 45.3 g of the above-mentioned photosensitive silver halide emulsion A
And 450 ml of pure water were added and stirred for 5 minutes. Next, 1M
702.6 ml of a silver nitrate solution of 2 are added over 2 minutes, and 1
After stirring for 0 minute, an organic silver salt dispersion was obtained. After that, the obtained organic silver salt dispersion was transferred to a water washing container, deionized water was added thereto, and the mixture was stirred and then allowed to stand to separate the organic silver salt dispersion by flotation to remove the water-soluble salts below. After that, the conductivity of the drainage is 2
Washing with deionized water and drainage were repeated until it became μS / cm, and centrifugal dehydration was carried out. The cake-like organic silver salt thus obtained had a water content of 0.1 depending on the operating conditions of a nitrogen gas atmosphere and a hot air temperature at the entrance of the dryer, using a flash dryer, a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.).
% To obtain a dried powder of an organic silver salt A.
An infrared moisture meter was used to measure the water content of the organic silver salt composition.

<< Preparation of Preliminary Dispersion A >> Polyvinyl butyral powder (manufactured by Monsanto, Butvar B-
79) Dissolve 14.57 g of methyl ethyl ketone in 1457 g and dissolver DI manufactured by VMA-GETZMANN
Preliminary Dispersion Liquid A was prepared by gradually adding 500 g of powdered organic silver salt A with stirring with a SPERMAT CA-40M type and thoroughly mixing.

<< Preparation of Photosensitive Emulsion Dispersion 1 >> Preliminary Dispersion A was filled with zirconia beads (Toray Treceram) having a diameter of 0.5 mm so that the residence time in the mill was 1.5 minutes by using a pump. Media type disperser filled with 80% of product DISPERMAT SL-C12EX type (VMA-G
ETZMANN) and dispersed at a mill peripheral speed of 8 m / s to prepare Photosensitive Emulsion Dispersion Liquid 1. << Preparation of stabilizer liquid >> 1.0 g of stabilizer-1, 0.31 g
The potassium acetate of was dissolved in 4.97 g of methanol to prepare a stabilizer solution.

[0102]

[Chemical 10]

<< Preparation of infrared sensitizing dye solution A >> 19.2 mg
Infrared sensitizing dye (SD-1), 1.488 g of 2-chloro-benzoic acid, 2.779 g of stabilizer-2 and 365.
Infrared sensitizing dye solution A was prepared by dissolving mg of 5-methyl-2-mercaptobenzimidazole in 31.3 ml of MEK in the dark.

[0104]

[Chemical 11]

<< Preparation of Additive Liquid a >> 1,1 as a Developer
-Bis (2-hydroxy-3,5-dimethylphenyl)
27.98 g of 2-methylpropane and 1.54 g of 4
-Methylphthalic acid, 0.48 g of the infrared dye-1
It was dissolved in 110 g of EK to obtain an additive liquid a. << Preparation of additive liquid b >> 3.56 g of antifoggant-2,
3.43 g of phthalazine was dissolved in 40.9 g of MEK to prepare an additive liquid b.

[0106]

[Chemical 12]

<< Preparation of Coating Solution for Photosensitive Layer >> The photosensitive emulsion dispersion 1 was prepared under an inert gas atmosphere (97% nitrogen).
(50 g) and MEK 15.11 g with stirring 2
The temperature was kept at 1 ° C., 390 μl of antifoggant-1 (10% methanol solution) was added, and the mixture was stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 20 minutes. Subsequently, 167 ml of the stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Then, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ℃, polyvinyl butyral (Monsanto
Butvar B-79) of the same company was added and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4% by mass MEK solution) was added and stirred for 15 minutes. While continuing stirring, 12.43 g of the additive liquid a, 1.6 ml of Desmodur N3300 / Morvey's aliphatic isocyanate (10% MEK solution), and 4.27 g of the additive liquid b were sequentially added and stirred. A photosensitive layer coating solution was obtained.

<< Preparation of Matting Agent Dispersion >> Cellulose Acetate Butyrate (Eastman Chemical)
Company, CAB171-15) 7.5g MEK 42.5g
Dissolved in calcium carbonate (Special)
itty Minerals, Super-Pflex
200) (5 g) was added and dispersed by a dissolver type homogenizer at 8000 rpm for 30 minutes to prepare a matting agent dispersion liquid.

<< Preparation of Coating Solution for Surface Protective Layer >> Cellulose acetate butyrate (Eastman Chemical) was stirred while stirring 865 g of MEK (methyl ethyl ketone).
Al, CAB171-15) 96 g, polymethylmethacrylic acid (Rohm & Haas, Paraloid A-21)
4.5 g, the following vinyl sulfone compound 1.5 g, benztriazole 1.0 g, and a fluorine-based activator (Asahi Glass Co., Ltd., Surflon KH40) 1.0 g were added and dissolved.
Next, 30 g of the above-mentioned matting agent dispersion liquid was added and stirred to prepare a surface protective layer coating liquid. Vinylsulfone compounds _{(CH 2 = CHSO 2 CH 2} ) 2 CHOH

<< Coating on Photosensitive Layer Surface Side >> A photosensitive material F100 was prepared by simultaneously coating the photosensitive layer coating solution and the surface protective layer coating solution in multiple layers using an extrusion coater. The coating is 1.9 on the photosensitive layer.
g / m ² , and the surface protective layer was formed so that the dry film thickness was 2.5 μm. After that, the drying temperature is 75 ℃ and the dew point is 1
Drying was performed for 10 minutes using 0 ° C. dry air.

(Preparation of Photosensitive Material F101A) << Preparation of Additive Solution c >> 5.0 g of the following silver saving agent was added to MEK4.
It melt | dissolved in 5.0 g and it was set as the addition liquid c.

[0112]

[Chemical 13] << Preparation of Photosensitive Layer Coating Liquid A >> In an inert gas atmosphere (nitrogen 9
7%), the photosensitive emulsion dispersion 1 (50 g) and MEK (15.11 g) were kept warm at 21 ° C. with stirring, and the chemical sensitizer S-5 (0.5% methanol solution) 1000 μm was added.
1 was added, and 2 minutes later, 390 μl of antifoggant-1 (10% methanol solution) was added, and the mixture was stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added, and the mixture was stirred for 10 minutes, and then the above chemical sensitizer S-5 was added to
/ 20 mol equivalent gold sensitizer Au-5 was added, and further 2
Stir for 0 minutes. Subsequently, 167 ml of the stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Then, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ℃,
Polyvinyl butyral (Monsanto Butv
13.31 g of ar B-79) was added and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4% by mass MEK solution) was added and stirred for 15 minutes. With further stirring, 12.43 g of the additive liquid a, 1.6 m
4. Desmodur N3300 / Mohbay aliphatic isocyanate (10% MEK solution), 4.27 g
The photosensitive layer coating liquid A was obtained by sequentially adding the additive liquid b) and stirring.

[0113]

[Chemical 14]

<< Preparation of Coating Solution B for Photosensitive Layer >> In an inert gas atmosphere (nitrogen 97%), the above-mentioned photosensitive emulsion dispersion 1 was prepared.
(50 g) and MEK 15.11 g with stirring 2
After keeping the temperature at 1 ° C, 1000 µl of chemical sensitizer S-5 (0.5% methanol solution) was added, and 2 minutes later, antifoggant-1
(10% methanol solution) (390 μl) was added, and the mixture was stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 10 minutes, and then a gold sensitizer Au-5 corresponding to 1/20 mol of the chemical sensitizer S-5 was added.
Was added and stirred for another 20 minutes. Then, the stabilizer liquid 16
After adding 7 ml and stirring for 10 minutes, 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Then, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes.
While keeping the temperature at 13 ℃, polyvinyl butyral (Mon
Santo Company Butvar B-79) 13.31 g
Was added and stirred for 30 minutes, then 1.084 g of tetrachlorophthalic acid (9.4% by mass MEK solution) was added and 1
Stir for 5 minutes. While continuing stirring, 12.43
g of addition liquid a, 1.6 ml of Desmodur N330
0 / Mobey's aliphatic isocyanate (10% M
EK solution), 4.27 g of Additive solution b, and 10.0 g of Additive solution c were sequentially added and stirred to obtain a photosensitive layer coating solution B.

(Preparation of Photosensitive Material F101A) A photosensitive material F101A was prepared in the same manner as the photosensitive material F100 except that the photosensitive layer surface side coating was changed to the following photosensitive layer surface side coating 101A.
Was produced. << Photosensitive Layer Surface-Side Coating 101A >> The photosensitive layer coating liquid A, the photosensitive layer coating liquid B, and the surface protective layer coating liquid are extruded by using an extrusion coater.
A total of 3 layers were simultaneously formed by multilayer coating. The application is
The photosensitive layer a formed from the photosensitive layer coating solution A has a coating silver amount of 0.
7 g / m ² , the photosensitive layer b formed from the photosensitive layer coating solution B has a coating silver amount of 0.3 g / m ² , and the surface protective layer has a dry film thickness of 2.
It was performed so as to have a thickness of 5 μm. Then, the drying temperature 50
Drying was performed for 10 minutes using a dry air having a dew point temperature of 10 ° C. (Preparation of Photosensitive Material F101B) Photosensitive Material F except that the coating on the photosensitive layer side was changed to the following photosensitive layer side coating 101B.
A light-sensitive material F101B was prepared in the same manner as 100. << Photosensitive Layer Surface-Side Coating 101B >> The photosensitive layer coating liquid A and the surface protective layer coating liquid were extruded (extrusion) to form a photosensitive layer a and a surface protective layer 1 layer at a time by multilayer coating. In addition, a photosensitive layer coating liquid B and a surface protective layer coating liquid are extruded on the opposite side of these two layers with a support interposed therebetween to form a total of two layers of a photosensitive layer b and a surface protective layer. At the same time, it was formed by multilayer coating. As for coating, the photosensitive layer a is coated with an amount of silver of 0.7 g /
m ² , the photosensitive layer b was coated with an amount of silver of 0.3 g / m ² , and the surface protective layer was dried to a thickness of 2.5 μm. Then, it was dried for 10 minutes using a drying air having a drying temperature of 50 ° C. and a dew point temperature of 10 ° C.

(Preparation of Photosensitive Material F102) << Preparation of Organic Silver Salt Dispersion >> Stearic acid 7 g, arachidic acid 4 g, behenic acid 36 g, distilled water 850 ml at 90 ° C.
1 mol / l NaOH with vigorous stirring
After adding 187 ml of an aqueous solution and reacting for 120 minutes and adding 71 ml of 1N-nitric acid, the temperature was lowered to 50 ° C. Then
125m of an aqueous solution of 21g of silver nitrate while stirring vigorously
1 was added over 100 seconds and left as it was for 20 minutes. Then, the solid content was filtered off by suction filtration, and the solid content was washed with water until the conductivity of the filtered water reached 30 μS / cm. 100 g of a 10 mass% aqueous solution of PVA205 (Kuraray Co., Ltd. polyvinyl alcohol) was added to the solid content thus obtained, and water was further added so that the total mass became 270 g, followed by coarse dispersion in an automatic mortar and organic A silver salt crude dispersion was obtained.
This crude organic silver salt dispersion was used as a nanomizer (Nanomizer Co., Ltd.).
Manufactured by K.K.) at a collision pressure of 98.07 MPa to obtain an organic silver salt dispersion. The organic silver salt particles contained in the obtained organic silver salt dispersion had an average short diameter of 0.04 μm and an average long diameter of 0.
The particles were acicular particles having a diameter of 8 μm and a coefficient of variation of 30%.

<< Preparation of Reducing Agent Dispersion >> 1,1-bis (2
-Hydroxy-3,5-dimethylphenyl) -3,5
To 100 g of 5-trimethylhexane (reducing agent) and 50 g of hydroxypropyl cellulose, 850 g of water was added and mixed well to obtain a slurry. The slurry has an average diameter of 0.5
The mixture was placed in a vessel together with 840 g of mm zirconia beads and dispersed for 5 hours with a disperser (1 / 4G sand grinder mill: manufactured by AIMEX Co., Ltd.) to obtain a reducing agent dispersion. << Preparation of Organic Polyhalide Dispersion >> 940 g of water was added to 50 g (0.127 mol) of tribromomethylsulfonylbenzene and 10 g of hydroxypropylcellulose and mixed well to form a slurry. The slurry was put in a vessel together with 840 g of zirconia beads having an average diameter of 0.5 mm, and dispersed for 5 hours by a disperser (sand grinder mill: manufactured by AIMEX Co., Ltd.) to obtain an organic polyhalide dispersion.

<< Preparation of Photosensitive Silver Halide Emulsion >> Water 10
22 g of phthalated gelatin and 30 mg of potassium bromide were dissolved in 00 ml and the pH was adjusted to 5.0 at a temperature of 35 ° C., then 18.6 g of silver nitrate and 0.
159 ml of an aqueous solution containing 9 g and 159 ml of an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of 92: 8 were added over 10 minutes by the control double jet method while keeping pAg at 7.7. Then silver nitrate 55.4
476 ml of an aqueous solution containing g and 2 g of ammonium nitrate
Then, an aqueous solution containing 10 μmol / liter of dipotassium hexachloroiridate and 1 mol / liter of potassium bromide was added over 30 minutes by the control double jet method while keeping pAg at 7.7, and then 4-hydroxy-6-
Methyl-1,3,3a, 7-tetrazaindene (1 g) was added, and the pH was further lowered to cause aggregation and sedimentation for desalting treatment. After that, 0.1 g of phenoxyethanol was added, and p
Adjusted to H5.9 and pAg8.2, silver iodobromide grains (iodine content core 8 mol%, average 2 mol%, average size 0.05
μm, projected area variation coefficient 8%, (100) plane ratio 85%
Cubic particles) were prepared. The silver halide grains thus obtained were heated to 60 ° C., and 85 μmol of sodium thiosulfate, 11 μmol of 2,3,4,5,6-pentafluorophenyldiphenylphosphine selenide, and 15 μmol of tellurium compound were added per mol of silver. After adding 3 μmol of chloroauric acid and 270 μmol of thiocyanic acid and aging for 120 minutes, 40
It was rapidly cooled to 0 ° C., then 100 μmol of sensitizing dye was added, and after stirring for 30 minutes, it was rapidly cooled to 30 ° C. to obtain a photosensitive silver halide emulsion. The above-mentioned 30 ° C. is the preparation temperature of the silver halide emulsion.

<< Preparation of Emulsion Layer Coating Solution >> Organic Silver Salt Dispersion 1
350 g, 140 m of 20 mass% aqueous solution of PVA205
l, 37 ml of a 10 mass% aqueous solution of phthalazine, 220 g of a reducing agent dispersion, and 61 g of an organic polyhalide dispersion were added, and then, LACSTAR LACSTAR 3307B.
(Manufactured by Dainippon Ink and Chemicals, Inc .; SBR latex containing styrene and butadiene as main copolymerization components;
Average particle size of dispersed particles: 0.1 to 0.15 μm, 25 ° C., 6
Polymer equilibrium water content of 0.6% by mass under 0% RH condition)
1100 g was mixed, and then 120 g of the above photosensitive silver halide emulsion was mixed to prepare emulsion layer coating solutions 1 to 8. The pH of the solution was adjusted to 11 p
It was adjusted to H5.0 to obtain an emulsion layer coating solution.

<< Preparation of Emulsion Surface Intermediate Layer Coating Solution >> MP203
(Modified polyvinyl alcohol manufactured by Kuraray Co., Ltd.) 10
0 g was dissolved in 900 ml of water, and 2 ml of a 5% by mass aqueous solution of sulfosuccinic acid di (2-ethylhexyl) ester sodium salt was added to obtain an emulsion surface intermediate layer coating solution. << Preparation of coating solution for emulsion surface protective layer >> Inert gelatin 1
To a solution prepared by dissolving 45 g in 1110 ml of warm water, 400 g of 20 mass% polyethyl acrylate latex, 1
Mol / liter sulfuric acid 57 ml, sulfosuccinic acid di (2-
10 ml of 5 mass% aqueous solution of ethylhexyl) ester sodium salt, 10 mass% methanol solution of phthalic acid 28
0 ml was added to obtain an emulsion surface protective layer coating solution. << Preparation of Emulsion Surface Overcoat Layer Coating Solution >> 129 g of inert gelatin was dissolved in 1650 ml of warm water.
Polymethylmethacrylate fine particles (average particle size 2.
A gelatin dispersion containing 12% by weight of
g, 1 mol / liter sulfuric acid 65 ml, and a liquid 1 to which 20 ml of a 5% by mass aqueous solution of sulfosuccinic acid di (2-ethylhexyl) ester sodium salt was added, a 2% by mass aqueous solution of potassium chromium (III) sulfate dodecahydrate ( Hardener)
Was used at a flow rate ratio of 0.3 to continuously prepare an emulsion surface overcoat layer coating solution.

<< Preparation of Back Layer Coating Liquid >> Solid bases N, N ', N ", N"'-tetraethylguanidine and 4
10 g of a salt of carboxysulfonyl-phenylsulfone in a molar ratio of 1: 2 with 10 g of polyvinyl alcohol,
88 g of water was dispersed with a sand grinder mill (manufactured by IMEX Co., Ltd.) to obtain a base liquid. 2.1 g of basic dye precursor, 7.9 g of acidic substance, 0.1 g (1.990 ×)
10 ^-4 mol) antihalation dye, ethyl acetate 10
Polyvinyl alcohol 1 was added to the organic solvent phase in which g was mixed and dissolved.
0 g and 80 g of water were mixed with an aqueous phase, and the mixture was emulsified and dispersed at room temperature to obtain a dye solution (average particle size 2.5 μm). 39 g of the base solution thus obtained, 26 g of the dye solution, and 36 g of a 10 mass% polyvinyl alcohol aqueous solution were mixed to obtain a back layer coating solution.

[0122]

[Chemical 15]

<< Back Layer Protective Layer Coating Liquid >> Gelatin 20
g, polymethylmethacrylate (average particle size 7 μm)
6 g, sodium dodecylbenzene sulfonate 0.4
g, X-22-2809 (silicone compound manufactured by Shin-Etsu Silicone Co., Ltd.) (1 g) was dissolved in 480 g of water to obtain a back layer protective layer coating solution. << Preparation of Undercoat Coating Liquid A >> Polyester copolymer dispersion (Pethresin A-515GB (solid content 30%) manufactured by Takamatsu Yushi Co., Ltd.) 200 ml, polystyrene fine particles (average particle size 0.2 μm) 50 g, surfactant A (1 mass%) 20m
1 was added, and distilled water was added to this to make 1000 ml to prepare an undercoating liquid A.

[0124]

[Chemical 16]

<< Preparation of Undercoat Coating Solution B >> Distilled water 680 m
200 ml of styrene-butadiene copolymer aqueous dispersion (styrene / butadiene / itaconic acid = 47/50/3 (mass ratio), concentration 30 mass%), and polystyrene fine particles (average particle size 2.5 μm) 0.1 g were added to 1 l. Then, distilled water was further added to 1000 ml to prepare an undercoat coating liquid B. << Preparation of Undercoat Coating Liquid C >> 10 g of inert gelatin was dissolved in 500 ml of distilled water, and the solution was added thereto.
40 g of an aqueous dispersion (40% by mass) of tin oxide-antimony oxide composite fine particles described in No. 3 was added, and distilled water was added to this to make 1000 ml to prepare an undercoating coating liquid C. << Preparation of Undercoat Support >> One side (photosensitive surface) of a biaxially stretched polyethylene terephthalate support having a thickness of 175 μm and colored with the following blue dye is subjected to corona discharge treatment, and then the undercoat coating solution A is wetted using a bar coater. Coating amount is 5
The solution was applied so that the amount became ml / m ² and dried at 180 ° C. for 5 minutes. The dry film thickness was about 0.3 μm. Then, after corona discharge treatment is applied to the back surface (back surface), the undercoat coating liquid B is applied with a bar coater to a wet coating amount of 5 ml.
/ M ² , a dry film thickness of about 0.3 μm was applied, and the coating was dried at 180 ° C. for 5 minutes, and the undercoating coating solution C was further applied thereon with a wet coating amount of 3 ml / using a bar coater.
m ² and a dry film thickness of about 0.03 μm were applied and dried at 180 ° C. for 5 minutes to prepare an undercoat support.

[0126]

[Chemical 17]

(Preparation of Photosensitive Material F102) On the back surface of the above-mentioned undercoat support, the back layer coating solution was added in an amount such that the optical density at 810 nm was 0.8, and the back layer protective layer coating solution was 50 g / m ^2. Stephen F. Kistler,
Peter M. "LIQUI" by Schweizer
D FILM COATING "(CHAPMAN & a
mp; published by HALL, 1997) Fig. 427
re 11b. Simultaneous multilayer coating with a coater similar to the coater described in 1 above, then 82 ml / m ^{2 of} emulsion layer coating solution from the support side to 6.5 ml / emulsion surface intermediate layer coating solution on the photosensitive surface.
m ² , the emulsion surface protective layer coating solution was 12.5 ml / m ² , and the emulsion surface overcoat layer coating solution was 12 ml / m ^2, and simultaneous multilayer coating was performed, and the mixture passed through a chilled zone of 10 ° C (dew point 0 ° C or less). Then, it was dried at 30 ° C., 40% RH, and a wind speed of 20 m / sec. The smoothness of the photosensitive material F102 thus obtained (the Beck's smoothness was examined by using the Oken type smoothness measurement described in J. TAPPI Paper Pulp Test Method No. 5) was 590 seconds on the emulsion side and 80 seconds on the back side. there were.

-Invention- << Exposure Treatment >> (Chest Phantom) An X-ray source of 120 kVp (aluminum transmission filter device of 3 mm thickness) was used, and a distance of 140
Place the Kyoto Scientific Chest Phantom at the position of cm, and behind it the anti-scatter grid with a grid ratio of 8: 1. Behind that, the radiation image conversion panel (P
1, P2 and P3) and photosensitive materials (SR-ESC (made by Konica Corporation), CM-H (made by Konica Corporation), SD-
P (manufactured by Konica Corporation), F100, F101A, F1
01B and F102) was placed and exposed. (ACR standard 156 type mammographic phantom) In the same manner, a mammographic image was captured using an ACR standard 156 type mammographic phantom manufactured by RMI. ACR standard 156 type mammographic phantom has 6 nylon fibers simulating the fiber structure.
States, 5 types of aluminum specs that mimic microcalcifications,
Five states of nylon fiber imitating a tumor are enclosed. << Development processing >> [Development processing of F100, F101A, F101B, and F102] Using an automatic developing machine having a heat drum, the protective layer of the photosensitive material and the drum surface are brought into contact with each other.
Heat development treatment was carried out at 0 ° C. for 15 seconds. The development process is 23
It was carried out in a room where the humidity was adjusted to 50 ° C and 50% RH. [Development processing of SR-ESC] Development processing was performed using SRX-502 (manufactured by Konica Corporation). [Development processing of CM-H] Development processing was performed using SRX-502 (manufactured by Konica Corporation). [SD-P Development Processing] Development processing was performed using Dry Pro722 (manufactured by Konica Corporation).

[Evaluation of Chest Phantom Image] The finished photograph of the chest phantom was visually observed, and graininess, sharpness, and silver tone were evaluated according to the following evaluation criteria. [Evaluation Criteria for Graininess] A: Almost inconspicuous B: Slightly conspicuous C: Slightly obstructive in interpretation of images D: Very conspicuous in interpretation of images [Evaluation criteria of sharpness] A: Very sharp B: Good but slightly There is blurring in C: Conspicuous blurring causes some trouble in interpretation D: Interpretation is difficult due to blurring

[Evaluation of Mammography Image] The evaluation was performed by observing how many nylon fibers simulating a fibrous tissue, aluminum specs simulating microcalcification, and nylon fibers simulating a tumor can be seen. ―Comparison― Using an X-ray source of 120 kVp (aluminum transmission filter device with a thickness of 3 mm), a chest phantom made by Kyoto Kagaku was placed at a distance of 140 cm, behind which was an anti-scatter grid with a grid ratio of 8: 1, behind which, A combination of a radiation image conversion panel (XG-S (manufactured by Konica Corporation)) and a photosensitive material (SR-ESC) is placed and exposed, and the photosensitive material (SR-ESC) is developed in the same manner as described above, The chest phantom image was evaluated according to the evaluation criteria. Similarly, a mammography image was photographed using an ACR standard 156 type mammography phantom manufactured by RMI. A radiation image conversion panel (MD-100 (manufactured by Konica Corporation)) is used as an assembly of the radiation image conversion panel and the photosensitive material.
And a photosensitive material (CM-H) were used. The light-sensitive material (CM-H) was developed in the same manner as described above, and the ACR standard 156 type mammographic phantom image was evaluated based on the evaluation criteria. Kyoto Science chest phantom and R
MI company ACR standard 156 type mammographic phantom digitizer (REGIUS MODEL15
0), and the image information is taken by a laser imager (D
output to the dry laser films SD-P and F100 using ry Pro 722), the photosensitive material (SD-P and F100) is developed in the same manner as described above, and the chest phantom image and ACR standard 156 type are obtained according to the evaluation criteria. Mammographic phantom images were evaluated. The obtained results are also shown in Table 2.

[0131]

[Table 2] As is clear from Table 2, the combination of the radiation image storage panel of the present invention and the silver salt photographic light-sensitive material has improved graininess and sharpness as compared with the comparison, and the diagnostic properties of medical images have improved.

[0132]

According to the present invention, high sharpness and graininess can be obtained, and the diagnosability of medical images is improved.

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Claims (7)

[Claims] 1. A silver salt photographic light-sensitive material using a radiation image conversion panel containing a phosphor having an oxygen atom O and at least one rare earth element selected from gadolinium Gd and europium Eu and having a crystallite size of 10 to 100 nm. An exposure method, which comprises exposing a material. 2. The phosphor is of the formula (Gd, M, Eu) ₂ O.
_3. The exposure method according to claim 1, wherein the exposure method is a phosphor including a phosphor represented by ₃ (M represents a rare earth element) as a constituent element. 3. The rare earth element M is at least one selected from yttrium Y, niobium Nd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, and ytterbium Yb. 2. The exposure method according to 2. 4. In the formula (Gd, M, Eu) ₂ O ₃ , gadolinium Gd is 40 to 95 mass%, M is 5 to 40 mass%, and europium Eu is 2 to 20 mass%. The exposure method according to claim 2 or 3. 5. The phosphor has an average particle size of 0.2 to 5 μm.
The exposure method according to claim 1, wherein the exposure method is m particles. 6. A silver halide photographic light-sensitive material, a light-sensitive emulsion containing organic silver salt particles, light-sensitive silver halide particles and a solvent,
6. The exposure method according to claim 1, which is a silver salt photothermographic dry imaging material having a photosensitive layer formed by applying a composition containing a reducing agent and a binder. 7. A silver salt photothermographic dry imaging material exposed by the exposure method according to claim 6, which has a temperature of 80 ° C. or higher.
An image forming method comprising developing by heating at a temperature of 00 ° C. or less.