JPH11249250A - Photosensitive heat-developed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide photosensitive heat-developed material of little unevenness of heat developing and excellent color tone and image keeping quality. SOLUTION: This photosensitive heat-developed material is so formed that maximum optical density in a photographic characteristic curve is 3.0 and that gamma value in optical density 1, 2 is 2.5 or less. A main binder of a photosensitive layer is a polymer with equilibrium moisture content at 25 deg.C 60% RH being 2 wt.% or less, and the photosensitive layer is formed using a coating solution with water accounting for 30 wt.% or more of a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive heat-developable material containing a photosensitive silver halide, and more particularly to a photographic light-sensitive material for a laser image setter or a laser imager (hereinafter referred to as an LI light-sensitive material). More specifically, it includes an LI photosensitive material that has a good silver tone when processed using a heat developing machine, has less unevenness due to heat development, has high sharp image quality, and has little change with time of the image. It relates to a single-sided photosensitive photographic material.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand in the medical field to reduce the amount of waste liquid from the viewpoint of environmental protection and space saving. Thus, photosensitive thermal development for medical diagnostics and photographic technology, which can be efficiently exposed by a laser imagesetter or laser imager and can form a sharp black image with high resolution and sharpness There is a need for materials technology. These photosensitive heat development materials eliminate the use of solution processing chemicals,
It is possible to supply a simpler and environmentally friendly thermal development processing system to customers.

In general, the characteristics required for such a photosensitive heat-developable material include general photographic characteristics such as sensitivity, contrast, and sharpness which are sufficient for medical diagnosis and other photographic technology applications. However, it is also important that there is no density fluctuation due to exposure or development, and that the obtained image does not deteriorate with time.

In response to such a request, for example,
JP-A-358144 describes prevention of high-illuminance reciprocity failure due to the inclusion of an iridium compound in silver halide, and spectroscopy based on the supersensitizing effect of a mercapto compound described in JP-A-7-341432. An increase in sensitivity is known. These conventional findings are aimed at enhancing general photographic characteristics (for example, sensitivity), and there is very little knowledge about changes in photographic characteristics per unit area of a photosensitive heat-developable material and improvement in deterioration of a silver image over time. Is the current situation.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive heat-developable material for medical diagnosis and photographic technology.
The purpose of the present invention is to provide a photosensitive heat-developable material having excellent performance such as high image density and good color tone, and photographic characteristics per unit area of the exposed and developed photosensitive material such as less heat development unevenness. Another object of the present invention is to provide a photothermographic material having a small change in image quality, and a photothermographic material which does not deteriorate the obtained silver image even after long-term aging.

[0006]

This object has been achieved by the present invention described below. (1) At least a photosensitive silver salt, an organic silver salt,
In a photothermographic material having a reducing agent and a binder and having at least one photosensitive layer containing the photosensitive silver salt, a photographic characteristic curve obtained by exposing and heat developing (the optical density is defined as the exposure energy Wherein the maximum optical density in a curve plotted against the common logarithm is 3.0 or more, and the gamma value at an optical density of 1.2 is 2.5 or less. (2) The main binder of the photosensitive layer is 25 ° C. and 60% RH.
The photosensitive heat according to the above (1), wherein the photosensitive layer is a polymer having an equilibrium water content of 2% by weight or less and the photosensitive layer is formed using a coating solution in which water is 30% by weight or more of a solvent. Developed photosensitive material. (3) The photothermographic material according to (1) or (2), wherein the same photosensitive layer contains at least two kinds of photosensitive silver salts having different effective sensitivities.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The photothermographic material of the invention contains a photosensitive silver salt, an organic silver salt (preferably an organic silver salt), a reducing agent and a binder, and has at least one layer of a photosensitive silver salt ( It preferably has a photosensitive layer containing an organic silver salt in addition to the photosensitive silver salt. Such a photosensitive heat-developable material has a maximum optical density (Dma) in a photographic characteristic curve.
x) is 3.0 or more, preferably 3.0 or more and 5.0
It is as follows. The gamma value at an optical density of 1.2 is 2.5 or less, preferably 1.0 or more and 2.5 or less.

[0008] In the present invention, the photographic characteristic curve is defined as the common logarithm (log E) of the exposure amount, which is the exposure energy, on the horizontal axis, and the optical density, ie, the scattered light photographic density (D), on the horizontal axis. Refers to the D-log E curve shown.
The gamma (G) value is defined as the optical density D =
This is the inclination of the tangent line in 1.2 (tan θ when the angle between the tangent line and the horizontal axis is θ). Further, in the present invention, the above-mentioned characteristic curve is obtained by performing exposure with a laser light source using a photosensitive heat developing material and performing appropriate development.

It is well known that the maximum optical density and gamma (G) value in a photographic characteristic curve affect image quality such as image sharpness and contrast. Therefore, it has been conventionally performed to adjust the maximum optical density and the gamma (G) value in order to obtain the image quality required for a photographic light-sensitive material (LI light-sensitive material) for a laser image setter or a laser imager. However, it has not been known that these characteristic values affect density unevenness at the time of thermal development and a change in an image after thermal development processing.

The present inventors have noticed and examined this correlation and found that the maximum optical density in the photographic characteristic curve was 3.0 or more,
In addition, by setting the gamma value at an optical density of 1.2 to 2.5 or less, the image quality required for a laser imagesetter or LI photosensitive material can be obtained. It has been found that changes in photographic characteristics per unit area of the photosensitive heat-developable material, such as changes in density and color tone, and image deterioration are remarkably improved. On the other hand, if the maximum optical density is less than 3.0, the image density becomes insufficient to obtain a good quality image, and if the gamma value at the optical density 1.2 exceeds 2.5, the color tone deteriorates, Heat development unevenness occurs, and the color tone changes easily due to storage.

In the present invention, a method of mixing and adding appropriate amounts of silver halides, which are photosensitive silver salts, having different effective sensitivities in order to change the characteristic curve can be used. Here, the effective sensitivity refers to the reciprocal of the exposure amount required to obtain a certain standard optical density when exposure is performed with a laser light source actually used and development processing is performed.

In order to change the sensitivity of silver halide, for example, the average grain size of silver halide is changed, the method of chemical sensitization or the degree of ripening is changed, or the spectral sensitizing dye adsorbed on silver halide is changed. There are methods such as changing the type and amount of addition, and any method may be used to change the sensitivity.

The photosensitive photothermographic material of the present invention (hereinafter also referred to as "sensitive material") has a photosensitive layer containing photosensitive silver halide as a photosensitive silver salt on at least one surface of a support. The main binder of the photosensitive layer according to the present invention is soluble or dispersible in an aqueous solvent (aqueous solvent).
It is preferable that the polymer has an equilibrium water content at 2% by weight (wt%) at 60 ° C. of 60% RH (hereinafter referred to as “polymer of the present invention”).

In the present invention, the use of the above-mentioned polymer makes it possible to coat a photosensitive layer using an aqueous solvent containing 30% by weight or more of water as a coating solvent. It is advantageous in terms of environment and cost as compared with.

The aqueous solvent in which the polymer of the present invention is soluble or dispersible means water or 70% by weight of water.
It is a mixture of the following water-miscible organic solvents. Examples of water-miscible organic solvents include, for example, methyl alcohol,
Examples thereof include alcohols such as ethyl alcohol and propyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

Note that the term "aqueous solvent" is used herein even in a system in which the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The term "equilibrium moisture content at 25 ° C. and 60% RH" used in the present invention refers to the weight W _{1 of} a polymer in a moisture-conditioning equilibrium in an atmosphere of 25 ° C. and 60% RH, and the weight of a polymer in an absolutely dry state at 25 ° C. Can be expressed as follows using the weight W ₀ of Equilibrium water content at 25 ° C. and 60% RH = ｛(W ₁ −W
₀ ) / W ₀ ｝ × 100 (% by weight)

The definition and measurement method of the water content can be referred to, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by The Society of Polymer Science, Jinjinshokan). The actual measurement can be performed as shown in Examples below.

The polymer of the present invention is not particularly limited as long as it is soluble or dispersible in the above-mentioned aqueous solvent and has an equilibrium water content at 25 ° C. and 60% RH of 2% by weight or less. Among these polymers, polymers that can be dispersed in an aqueous solvent are particularly preferred.

The equilibrium water content of the polymer of the present invention at 25 ° C. and 60% RH is preferably 2% by weight or less.
More preferably, it is 0.01% by weight or more and 1.5% by weight or less, further preferably 0.02% by weight or more and 1% by weight or less.

In a preferred embodiment of the present invention, acrylic resin, polyester resin, rubber resin (for example, S
(BR resin), a polyurethane resin, a vinyl chloride resin, a vinyl acetate resin, a vinylidene chloride resin, a hydrophobic polymer such as a polyolefin resin. The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized, or a copolymer in which two or more 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 preferably from 5000 to 100000, more preferably from 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the emulsion layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

The polymer of the present invention is a polymer in which these polymers are dispersed in an aqueous dispersion medium. Here, the aqueous system refers to a dispersion medium in which 30% by weight or more of the composition is water. Emulsified dispersion, micellar dispersion,
Further, any polymer may be used, such as a polymer having a hydrophilic portion in a molecule dispersed in a molecular state, and of these, latex is particularly preferable.

The polymer latex referred to here is a polymer in which a water-insoluble hydrophobic polymer is dispersed as fine particles in a water-soluble dispersion medium. The dispersion state is such that the polymer is emulsified in a dispersion medium, emulsion-polymerized, micelle-dispersed, or partially dispersed in polymer molecules and molecular chains themselves are molecularly dispersed. Any of them may be used.

The polymer latex of the present invention is described in "Synthetic Resin Emulsion (Taira Okuda, Hiroshi Inagaki, published by Kobunshi Kanko (1978))", "Application of Synthetic Latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Edited by Keiji Kasahara, published by the Society of Polymer Publishing (1993)), and "Synthesis of Synthetic Latex (Souichi Muroi, published by the Society of Polymer Publishing (1970))".

The average particle size of the dispersed particles is preferably in the range of 1 to 50,000 nm, more preferably in the range of about 5 to 1000 nm. There is no particular limitation on the particle size distribution of the dispersed particles.

Specific examples of preferred polymers include the following.

P-1; -MMA ₅₀ -EA ₄₅ -MAA _5-
Latex (molecular weight _{37000) P-2; -MMA 70} -2EHA 20 -St 5 -AA 5 - latex (molecular weight 40000) of _{P-3; -St 70 -Bu 25} -AA 5 - latex (molecular weight 60000) P _{-4; -St 60 -Bu 35 -DVB 3} -MAA 2 - latex (molecular weight _{150000) P-5; -VC 50} -MMA 20 -EA 20 -AN 5 -AA 5
- latex (molecular weight 80,000) of _{P-6; -VDC 85 -MMA 5} -EA 5 -MAA 5 - latex (molecular weight _{67000) P-7; -Et 90} -MAA 10 - Latex (molecular weight 12
000)

The abbreviations of the above structures represent structural units derived from the following monomers. MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2 ethylhexyl acrylate, St;
Styrene, Bu; butadiene, AA; acrylic acid, DV
B; divinylbenzene, VC; vinyl chloride, AN; acrylonitrile, VDC; vinylidene chloride, Et; ethylene. The numerical values are wt% and the molecular weight is the number average molecular weight.

The polymers described above are also commercially available, and the following polymers can be used. Examples of the acrylic resin include Sebian A-4635,46583,4601 (all manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 82
Examples of polyester resins such as 0,857 (all manufactured by Zeon Corporation) include FINETEX ES650, 611, 675, 850 (all manufactured by Dainippon Ink & Chemicals, Inc.), WD-size, WMS (all Eastman Examples of polyurethane resins include HYDRAN AP10, 20, 30, and 40 (all manufactured by Dainippon Ink and Chemicals, Inc.). Examples of rubber resins include LACSTAR.
Examples of vinyl chloride resins such as 7310K, 3307B, 4700H, and 7132C (all manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx416, 410, 438C, and 2507 (all manufactured by Zeon Corporation) are G3
Examples of vinylidene chloride resins include L502 and L513 (manufactured by Asahi Kasei Kogyo Co., Ltd.). Examples of olefin resins include Chemipearl S120 and SA100 (manufactured by Mitsui. Petrochemical Co., Ltd.). These polymers may be used alone or as a mixture of two or more as necessary.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is from 40:60 to 95: 5, more preferably 5: 5.
The ratio is preferably from 0:50 to 90:10. The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99% by weight. The preferred molecular weight range is the same as described above.

Styrene which is preferably used in the present invention
As the latex of butadiene copolymer, the above-mentioned P-
3, P-4, commercially available LACSTAR3307B,
7132C, Nipol Lx416 and the like.

The main binder in the photosensitive layer of the present invention means that 50% by weight or more, more preferably 70% by weight or more of the total binder in the photosensitive layer is the polymer of the present invention.

These binders may use the polymer of the present invention alone, or may blend two or more of them if necessary. If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, or hydroxypropylcellulose may be added to the photosensitive layer (emulsion layer) of the light-sensitive material of the present invention. The addition amount of these hydrophilic polymers is preferably 30% by weight or less, more preferably 20% by weight or less of the total binder in the photosensitive layer.

The amount of the binder in the photosensitive layer according to the present invention is preferably such that the weight ratio of (total binder) / (silver halide) is in the range of 400 to 5, more preferably 200 to 100.

The solvent of the coating solution for the emulsion layer of the photosensitive heat-developable material of the present invention (for the sake of simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is an aqueous solvent containing 30% by weight or more of water. . As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent of the coating solution is preferably at least 50% by weight, more preferably at least 70% by weight. Preferred examples of the solvent composition include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol /
Dimethylformamide = 80/15/5, water / methyl alcohol / ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5 (numerical values are% by weight) and the like.

The organic silver salt that can be used in the present invention includes:
Relatively stable to light, but forms a silver image when heated to 80 ° C. or higher in the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent It is a silver salt. The organic silver salt can be any organic substance including a source capable of reducing silver ions. Silver salts of organic acids, in particular silver salts of long-chain fatty carboxylic acids (with 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Complexes of organic or inorganic silver salts wherein the ligand has a complex stability constant in the range of 4.0 to 10.0 are also preferred. The silver donor is preferably present in about 5-70 of the imaging layer.
% By weight. Preferred organic silver salts include silver salts of organic compounds having a carboxyl group. Examples of these include, but are not limited to, silver salts of aliphatic carboxylic acids and silver salts of aromatic carboxylic acids. Preferred examples of the silver salt of an aliphatic carboxylic acid include silver behenate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver maleate, silver fumarate, and tartaric acid. Silver, silver linoleate, silver butyrate and silver camphorate, and mixtures thereof.

Silver salts of compounds containing a mercapto group or a thione group and derivatives thereof can also be used.
Preferred examples of these compounds include 3-mercapto-4
-Phenyl-1,2,4-triazole silver salt, 2-mercaptobenzimidazole silver salt, 2-mercapto-5-aminothiadiazole silver salt, 2- (ethylglycolamide) benzothiazole silver salt, S- Silver salts of thioglycolic acid such as silver salts of alkylthioglycolic acid (where the alkyl group has 12 to 22 carbon atoms), silver salts of dithiocarboxylic acids such as silver salts of dithioacetic acid, silver salts of thioamides, 5 -Carboxyl-1-methyl-2-phenyl-4-thiopyridine silver salt, mercaptotriazine silver salt, 2-mercaptobenzoxazole silver salt, silver salts described in U.S. Pat.No.4,123,274, for example, 3-amino-5- Silver salts of 1,2,4-mercaptothiazole derivatives such as benzylthio-1,2,4-thiazole silver salt, 3- (3-carboxyethyl) -4-methyl-4-thiazoline described in U.S. Pat.No. 3,301,678 Of thione compounds such as silver salt of -2-thione Including the salt. Furthermore, compounds containing an imino group can also be used. Preferred examples of these compounds include:
Silver salts of benzotriazole and their derivatives, e.g. silver salts of benzotriazole such as silver methylbenzotriazole, silver salts of halogen-substituted benzotriazoles such as silver 5-chlorobenzotriazole, U.S. Pat.
Silver salts of 1,2,4-triazole or 1-H-tetrazole, silver salts of imidazole and imidazole derivatives, and the like. For example, various silver acetylide compounds as described in U.S. Pat. Nos. 4,761,361 and 4,775,613 can also be used.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, but a needle crystal having a short axis and a long axis is preferable. In the present invention, the minor axis is 0.01 μm or more and 0.2 μm or more.
0 μm or less, major axis of 0.10 μm or more and 5.0 μm or less, minor axis of 0.01 μm or more and 0.15 μm or less, and major axis of 0.10 μm or more and 4.0 μm or less are more preferred. The particle size distribution of the organic silver salt is preferably monodispersed. Monodisperse and the minor axis, the percentage of the value obtained by dividing the standard deviation of the length of each major axis by each minor axis, major axis is preferably 100% or less, more preferably 80% or less,
More preferably, it is 50% or less. The shape of the organic silver salt can be measured from a transmission electron microscope image of the organic silver salt dispersion. As another method of measuring the monodispersity, there is a method of determining the standard deviation of the volume-weighted average diameter of the organic silver salt, the percentage of the value divided by the volume-weighted average diameter (coefficient of variation) is preferably 100% or less, more Preferably 80% or less,
More preferably, it is 50% or less. As a measuring method, for example, the particle size (volume weighted average diameter) obtained by irradiating a laser beam to an organic silver salt dispersed in a liquid and obtaining an autocorrelation function with respect to a time change of fluctuation of the scattered light is obtained. Can be.

The organic silver salt that can be used in the present invention is
Preferably, desalting can be performed. The method for desalting is not particularly limited, and a known method can be used. However, a known filtration method such as centrifugal filtration, suction filtration, ultrafiltration, or floc-forming water washing by a coagulation method can be preferably used.

For the purpose of obtaining fine particles having a small particle size and no aggregation, a method of preparing a solid fine particle dispersion using a dispersant is used for the organic silver salt which can be used in the present invention. The method of dispersing the organic silver salt into solid fine particles is carried out by using a known fine means (for example, a ball mill, a vibrating ball mill, a planetary ball mill, a sand mill, a colloid mill, a jet mill, a roller mill) in the presence of a dispersing agent. Can be dispersed.

When the organic silver salt is formed into solid fine particles using a dispersant, for example, polyacrylic acid, a copolymer of acrylic acid, a maleic acid copolymer, a maleic acid monoester copolymer, and acryloylmethyl Synthetic anionic polymers such as propanesulfonic acid copolymers, semi-synthetic anionic polymers such as carboxymethyl starch and carboxymethyl cellulose, anionic polymers such as alginic acid and pectic acid, and JP-A-52-92716, WO88 / 04794, etc. Anionic surfactant described, the compound described in Japanese Patent Application No. 7-350753, or known anionic, nonionic,
Cationic surfactants and other known polymers such as polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose, or high-molecular compounds existing in nature such as gelatin can be appropriately selected and used. .

It is a general method to mix a dispersion aid with an organic silver salt powder or an organic silver salt in a wet cake state before dispersion and to send the mixture to a dispersion machine as a slurry. Heat treatment or treatment with a solvent may be performed in the combined state to obtain an organic silver salt powder or a wet cake. The pH may be controlled by a suitable pH adjuster before, during or after dispersion.

Instead of mechanically dispersing, fine particles may be formed by coarsely dispersing in a solvent by controlling the pH and then changing the pH in the presence of a dispersing agent. At this time, an organic solvent may be used as a solvent used for the coarse dispersion, and the organic solvent is usually removed after the completion of the fine particle formation.

The prepared dispersion is stored with stirring for the purpose of suppressing sedimentation of fine particles during storage, or stored in a highly viscous state by a hydrophilic colloid (for example, in a jelly state using gelatin). You can also do.
Further, a preservative can be added for the purpose of preventing the propagation of various bacteria during storage.

The organic silver salt of the present invention can be used in a desired amount, preferably 0.1-5 g / m ² indicates the coating amount per photographic material 1 m ^2, more preferably from 1 to 3 g / m ^2.

The method of forming the photosensitive silver halide in the present invention is well known in the art, and uses, for example, the methods described in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. be able to. The grain size of the photosensitive silver halide is preferably small for the purpose of suppressing the white turbidity after image formation, specifically 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less, further more preferably 0.02 μm or more. 0.12μm
The following is good. Here, the grain size means the length of the edge of the silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case where the silver halide grains are tabular grains, the diameter refers to a diameter when converted into a circular image having the same area as the projected area of the main surface. In the case of other than normal crystals, for example, in the case of spherical grains, rod-shaped grains, etc., it refers to the diameter of a sphere equivalent to the volume of silver halide grains.

The shape of the silver halide grains is cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned. In the present invention, cubic particles and tabular particles are particularly preferable. When tabular silver halide grains are used, the average aspect ratio is preferably 100: 1 to 2: 1, more preferably 50: 1 to 3: 1. Further, grains having rounded corners of silver halide grains can also be preferably used. The surface index (mirror index) of the outer surface of the photosensitive silver halide grains is not particularly limited, but it is preferable that the proportion of the surface having high spectral sensitization efficiency when the spectral sensitizing dye used is adsorbed is high. . The ratio is preferably at least 50%, more preferably at least 65%, even more preferably at least 80%. The ratio of the Miller index is determined by the method described in T. Tani; J. Imaging Sci., 29, 165 (1985), which utilizes the adsorption dependence of the {111} plane and the {100} plane in the adsorption of the sensitizing dye. You can ask. The halogen composition of the photosensitive silver halide is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver bromide, silver iodobromide, silver iodochlorobromide, and silver iodide. In the present invention, silver bromide or silver iodobromide can be preferably used. Particularly preferred is silver iodobromide, and the silver iodide content is preferably from 0.1 mol% to 40 mol%, and more preferably from 0.1 mol% to 20 mol%.
The following is more preferred. The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be changed continuously.

In the present invention, it is preferred that after the silver halide grains are formed, a water-soluble halide of a halogen different from the grain formation is added to carry out halogen conversion on the grain surface.

The photosensitive silver halide grains of the present invention preferably contain at least one complex of a metal selected from rhodium, rhenium, ruthenium, osmium, iridium, cobalt, mercury or iron. One type of these metal complexes may be used, or two or more types of complexes of the same metal and different metals may be used in combination. The preferable content is in the range of 1 nmol to 1 mmol, and more preferably in the range of 10 nmol to 100 μmol per 1 mol of silver. As a specific structure of the metal complex, a metal complex having a structure described in JP-A-7-225449 or the like can be used. As the compound of cobalt and iron, a hexacyano metal complex can be preferably used. Specific examples include ferricyanate ion, ferrocyanate ion, hexacyanocobaltate ion, and the like, but are not limited thereto. The content of the metal complex in the silver halide may be uniform, may be contained at a high concentration in the core portion, or may be contained at a high concentration in the shell portion, and there is no particular limitation.

The photosensitive silver halide grains can be desalted by washing with a method known in the art, such as a noodle method or flocculation method, but in the present invention, it may or may not be desalted. .

The photosensitive silver halide grains in the present invention are preferably chemically sensitized. As a preferred chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, and a tellurium sensitization method are well known in the art. Further, a noble metal sensitization method or a reduction sensitization method of a gold compound, platinum, palladium, an iridium compound or the like can be used. As the compound preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method, known compounds can be used, and the compounds described in JP-A-7-128768 can be used. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Te Compounds having a bond, tellurocarboxylates, Te-organyltellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, P-Te
Compounds having a bond, Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used. Compounds preferably used for the noble metal sensitization method include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, or U.S. Pat.
Compounds described in 18,061 and the like can be preferably used. As specific compounds of the reduction sensitization method, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like can be used. . Reduction sensitization can be achieved by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less. Further, reduction sensitization can be achieved by introducing a single addition portion of silver ion during grain formation.

The amount of the photosensitive silver halide used in the present invention is preferably 0.01 mol to 0.5 mol, more preferably 0.02 mol to 0.3 mol, and more preferably 0.03 mol to 1 mol of the organic silver salt. It is particularly preferably at least 0.25 mol and not more than 0.25 mol.

As the sensitizing dye in the present invention, any dye can be used as long as it can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains. As the sensitizing dye, a cyanine dye, a merocyanine dye, a complex cyanine dye, a complex merocyanine dye, a holopolar cyanine dye, a styryl dye, a hemicyanine dye, an oxonol dye, a hemioxonol dye, and the like can be used. Useful sensitizing dyes for use in the present invention include, for example, RESEARCH DISCLOSURE Item 17
Item 643IV-A (p.23, December 1978), Item 1831X (August 1979)
p.437) or in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers, scanners, imagesetters and plate making cameras can be advantageously selected.

An example of spectral sensitization to red light is He-Ne
For lasers, so-called red light sources such as red semiconductor lasers and LEDs, I-1 to I-1 described in JP-A-54-18726.
-38, the compound of I-1 to I-35 described in JP-A-6-75322 and the compound of I-1 to I-34 described in JP-A-7-287338, JP-B-55-39818 Dyes 1 to 20 described, compounds of I-1 to I-37 described in JP-A-62-284343 and compounds of I-1 to I-34 described in JP-A-7-287338 are advantageously selected. Is done.

For a semiconductor laser light source in the wavelength region of 750 to 1400 nm, various known dyes including cyanine, merocyanine, styryl, hemicyanine, oxonol, hemioxonol and xanthene dyes are spectrally advantageously sensitized. Can be done. Useful cyanine dyes are, for example, cyanine dyes having basic nuclei such as thiazoline nuclei, oxazoline nuclei, pyrroline nuclei, pyridine nuclei, oxazole nuclei, thiazole nuclei, selenazole nuclei and imidazole nuclei. Preferred useful merocyanine dyes include, in addition to the above basic nuclei, acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus. Including. Among the above cyanine and merocyanine dyes, those having an imino group or a carboxyl group are particularly effective. For example, U.S. Patent 3,761,279,
3,719,495 and 3,877,943, British Patent 1,466,201
No. 1,469,117, No. 1,422,057, Tokuhei 3-10391
No. 6-52387, JP-A-5-341432, 6-94781,
It may be appropriately selected from known dyes as described in JP-A-6-301141.

Particularly preferred as the structure of the dye used in the present invention is a cyanine dye having a thioether bond-containing substituent (for example, see JP-A-62-58239 and JP-A-3-13863).
No.8, No.3-138642, No.4-255840, No.5-72659, No.5-
72661, 6-222491, 2-230506, 6-258757
No., 6-317868, 6-324425, Tokuyohei 7-500926,
Dyes described in U.S. Pat.No. 5,541,054), dyes having a carboxylic acid group (for example, JP-A-3-163440, 6-30114
No. 1, U.S. Pat.No. 5,441,899), merocyanine dyes, polynuclear merocyanine dyes and polynuclear cyanine dyes
(JP 47-6329, JP 49-105524, JP 51-127719, JP
52-80829, 54-61517, 59-214846, 60-6750
No. 63-159841, JP-A-6-35109, JP-A-6-59381,
Nos. 7-146537, 7-46537, JP-T-55-50111, British Patent 1,467,638, and US Pat. No. 5,281,515).

Further, as a dye forming a J-band, a dye described in Example 5 of US Pat. Nos. 5,510,236 and 3,871,887,
JP-A-2-96131 and JP-A-59-48753 are disclosed and can be preferably used in the present invention.

These sensitizing dyes may be used alone.
Two or more kinds may be used in combination. Combinations of sensitizing dyes are often used, especially for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization. Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are
Research Disclosure Volume 176, 17643 (December 1978) No. 23
Section IV of Page IV, or JP-B-49-25500, 43-43933,
These are described in JP-A-59-19032 and JP-A-59-192242.

Two or more sensitizing dyes may be used in combination in the present invention. The sensitizing dyes can be added to the silver halide emulsion by dispersing them directly in the emulsion or by adding water, methanol, ethanol, propanol, acetone, methyl cellosolve, 2,2,3,3- Tetrafluoropropanol, 2,2,2-trifluoroethanol, 3-methoxy-1-propanol, 3-methoxy-1-butanol, 1-methoxy-2-propanol, N, N-dimethylformamide alone or It may be dissolved in a mixed solvent and added to the emulsion.

As disclosed in US Pat. No. 3,469,987, a dye is dissolved in a volatile organic solvent, and this solution is dispersed in water or a hydrophilic colloid. Method of adding to Japanese Patent Publication No. 44-23389,
As disclosed in JP-A-44-27555 and JP-A-57-22091, a dye is dissolved in an acid and this solution is added to the emulsion, or an acid or base is added to the emulsion as an aqueous solution in the presence of an acid or base. A method of adding an aqueous solution or a colloidal dispersion in the presence of a surfactant to an emulsion as disclosed in U.S. Patent Nos. 3,822,135 and 4,006,025, JP-A-51-746, a method in which a dye is directly dispersed in a hydrophilic colloid and the dispersion is added to an emulsion as disclosed in JP-A-51-746.
As disclosed in JP-A No. 24, a method of dissolving a dye using a compound that causes a red shift and adding this solution to an emulsion can also be used. Also, ultrasonic waves can be used for dissolution.

The sensitizing dye used in the present invention may be added to the silver halide emulsion of the present invention at any time during the preparation of the emulsion which has been found to be useful. For example, U.S. Patents 2,735,766 and 3,628,960,
4,183,756, 4,225,666, JP-A-58-184142,
As disclosed in the specification of JP-A-60-196749 and the like, the timing before silver halide grain forming step and / or desalting, during and / or after desalting and before the start of chemical ripening. As disclosed in the specification such as JP-A-58-113920, any time immediately before chemical ripening or during the process, after chemical ripening, and before coating the emulsion before coating It may be added at the time and in the process.
Further, as disclosed in the specification of U.S. Pat. No. 4,225,666, JP-A-58-7629, etc., the same compound may be used alone or in combination with a compound having a different structure, for example, during the particle forming step. The compound may be divided and added during the ripening step or after the completion of the chemical ripening, or may be added separately before or during the chemical ripening or after the completion of the chemical ripening. May be added.

The sensitizing dye may be added at any time as described above, but it is preferable to add the sensitizing dye after the silver halide grains are formed and before the silver halide is added to the aqueous solvent coating solution. preferable. The amount of the sensitizing dye used in the present invention may be a desired amount in accordance with the performance such as sensitivity and fog, but may be 1 to 1 per mol of silver halide in the photosensitive layer.
It is preferably 0 ^-6 to ¹ mol, more preferably 10 ^-4 to 10 ^-1 mol.

The reducing agent for the organic silver salt may be any substance which reduces silver ions to metallic silver, preferably an organic substance. Conventional photographic developers such as phenidone, hydroquinone and catechol are useful, but hindered phenol reducing agents are preferred. The reducing agent is preferably contained in an amount of 5 to 50% (mole), more preferably 10 to 40% (mole), based on 1 mol of silver on the surface having the image forming layer. The layer to which the reducing agent is added may be any layer on the side having the image forming layer. When it is added to a layer other than the image forming layer, it is preferable to use a relatively large amount of 10 to 50% (mol) with respect to 1 mol of silver. Further, the reducing agent may be a so-called precursor which is derivatized so as to have a function effectively only during development.

In photosensitive heat-developable materials utilizing organic silver salts, a wide range of reducing agents are disclosed in JP-A-46-6074 and JP-A-47-1238.
Nos. 47-33621, 49-46427, 49-115540, 5
0-14334, 50-36110, 50-147711, 51-32632
No. 51-10223721, No. 51-32324, No. 51-51933, No.
52-84727, 55-108654, 56-146133, 57-828
No. 28, No. 57-82829, JP-A-6-3793, U.S. Pat.
9586, 3,679,426, 3,751,252, 3,751,255
Nos. 3,761,270, 3,782,949, 3,839,048,
No. 3,928,686, No. 5,464,738, German patent 2,321,328
And European Patent 692,732. For example, amide oximes such as phenylamidooxime, 2-thienylamidooxime and p-phenoxyphenylamidooxime; azines such as 4-hydroxy-3,5-dimethoxybenzaldehydeazine; 2,2-bis (hydroxymethyl) propionyl- a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid, such as a combination of β-phenylhydrazine and ascorbic acid; a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine (eg, hydroquinone, bis (ethoxyethyl) ) Hydroxylamine, piperidinohexose reductone or a combination of formyl-4-methylphenylhydrazine)); phenylhydroxamic acid, p-hydroxyphenylhydroxamic acid and β
Hydroxamic acids such as -alanine hydroxamic acid; combinations of azines and sulfonamidophenols (eg, phenothiazine and 2,6-dichloro-4-benzenesulfonamidophenol); ethyl-α-cyano-2-methylphenylacetate; Α-cyanophenylacetic acid derivatives such as ethyl-α-cyanophenylacetate; 2,2-dihydroxy-
1,1-binaphthyl, 6,6-dibromo-2,2-dihydroxy-1,1-
Bis-β-naphthol as exemplified by binaphthyl and bis (2-hydroxy-1-naphthyl) methane; bis-β-naphthol and 1,3-dihydroxybenzene derivatives (for example,
Combination of 2,4-dihydroxybenzophenone or 2,4-dihydroxyacetophenone); 3-methyl-1-phenyl
5-pyrazolone, such as -5-pyrazolone; reductones as exemplified by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone;
Sulfonamidophenol reducing agents such as 2,6-dichloro-4-benzenesulfonamidophenol and p-benzenesulfonamidophenol; 2-phenylindane-1,3-
Diones and the like; chromanes such as 2,2-dimethyl-7-t-butyl-6-hydroxychroman; 1,4-dihydropyridines such as 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine; Bisphenols (e.g., bis (2-hydroxy
-3-t-butyl-5-methylphenyl) methane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 4,4-ethylidene
-Bis (2-t-butyl-6-methylphenol), 1,1, -bis (2
-Hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane and the like); ascorbic acid derivatives (for example, palmitic acid 1 And aldehydes and ketones such as benzyl and biacetyl; 3-pyrazolidone and certain indan-1,3-diones; chromanol (such as tocopherol). Particularly preferred reducing agents are bisphenol and chromanol.

The reducing agent of the present invention may be added by any method such as a solution, a powder, and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

When an additive known as a "toning agent" for improving an image is contained, the optical density may be increased. The toning agent may also be advantageous in forming a black silver image. The toning agent is preferably contained in an amount of 0.1 to 50% (mole) per mole of silver on the surface having the image forming layer, and more preferably 0.5 to 20% (mole). Further, the toning agent may be a so-called precursor which is derivatized so as to have a function effectively only during development.

In photosensitive heat-developable materials utilizing organic silver salts, a wide range of color toning agents are disclosed in JP-A-46-6077 and JP-A-47-10282.
Nos. 49-5019, 49-5020, 49-91215, 49-9
No. 1215, No. 50-2524, No. 50-32927, No. 50-67132,
No. 50-67641, No. 50-114217, No. 51-3223, No. 51-279
No. 23, No. 52-14788, No. 52-99813, No. 53-1020, No. 5
3-76020, 54-156524, 54-156525, 61-1836
No. 42, JP-A-4-56848, JP-B-49-10727, 54-2033
No. 3, U.S. Pat.Nos. 3,080,254, 3,446,648, 3,782,9
No. 41, No. 4,123,282, No. 4,510,236, British Patent 138079
No. 5, Belgian Patent No. 841910 and the like. Examples of toning agents are phthalimide and N-hydroxyphthalimide; succinimide, pyrazolin-5-one, and quinazolinone, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-thiazolidinedione Cyclic imides such as; naphthalimides (eg, N
-Hydroxy-1,8-naphthalimide); cobalt complexes (eg, cobalt hexamine trifluoroacetate); 3-
Mercapto-1,2,4-triazole, 2,4-dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiadiazole N- (aminomethyl) aryldicarboximides, such as (N, N-dimethylaminomethyl) phthalimide and N, N- (dimethylaminomethyl) -naphthalene-2,3-dicarboximide ); And blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N'-hexamethylenebis (1-
Carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-diazaoctane) bis (isothiuronium trifluoroacetate) and 2-tribromomethylsulfonyl)-(benzothiazole)); and 3-ethyl- 5 [(3-ethyl-2-benzothiazolinylidene) -1-methylethylidene] -2-thio-2,4
-Oxazolidinedione; phthalazinone, phthalazinone derivative or metal salt, or 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione A combination of phthalazinone and a phthalic acid derivative (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride, etc.); phthalazine,
Phthalazine derivatives or metal salts, or derivatives such as 4- (1-naphthyl) phthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine and 2,3-dihydrophthalazine; phthalazine and phthalic acid derivatives (for example, phthalic acid) Acid, 4
-Methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride); quinazolinedione,
Benzoxazine or naphthoxazine derivatives; rhodium complexes that function not only as color tone regulators but also in-situ as sources of halide ions for silver halide formation, such as ammonium hexachlororhodate (III), rhodium bromide, rhodium nitrate And potassium hexachlororhodate (III); inorganic peroxides and persulfates, such as ammonium disulfide and hydrogen peroxide; 1,3-benzoxazine-2,4-dione, 8-methyl-
1,3-benzoxazine-2,4-dione and 6-nitro-1,3-
Benzoxazines such as benzoxazine-2,4-dione
2,4-dione; pyrimidine and asymmetric-triazine (eg, 2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine, etc.), azauracil, and tetraazapentalene derivatives (eg, 3,6-dimercapto- 1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene, and 1,4-di (o-chlorophenyl) -3,6-dimercapto-1H, 4
H-2,3a, 5,6a-tetraazapentalene).

The color-toning agent of the present invention may be added by any method such as a solution, a powder, and a solid fine particle dispersion. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

The silver halide emulsion according to the present invention or /
And the organic silver salts can be further protected against the formation of additional fog by antifoggants, stabilizers and stabilizer precursors, and can be stabilized against reduced sensitivity during storage in inventory. Suitable antifoggants, stabilizers and stabilizer precursors which can be used alone or in combination are the thiazonium salts described in U.S. Pat.Nos. 2,131,038 and 2,694,716, U.S. Pat.Nos. 2,886,437 and 2,444,6
Azaindene described in No. 05, mercury salt described in U.S. Pat.No. 2,728,663, urazole described in U.S. Pat.No. 3,287,135, sulfocatechol described in U.S. Pat.No.3,235,652,
Oxime described in British Patent No. 623,448, nitrone, nitroindazole, polyvalent metal salt described in U.S. Pat.No. 2,839,405, thyuronium salt described in U.S. Pat.No.3,220,839,
And palladium, platinum and gold salts described in U.S. Pat.Nos. 2,566,263 and 2,597,915, U.S. Pat.
No. 665 and 4,442,202, halogen-substituted organic compounds described in U.S. Pat.Nos. 4,128,557 and 4,137,079,
138,365 and 4,459,350, and the phosphorus compounds described in US Pat. No. 4,411,985.

The antifoggant preferably used in the present invention is an organic halide, for example, as described in JP-A-50-119624.
No. 50-120328, No. 51-121332, No. 54-58022, No.
56-70543, 56-99335, 59-90842, 61-12964
No. 2, 62-129845, JP-A-6-208191, 7-5621,
No. 7-2781, No. 8-15809, U.S. Pat.No. 5,340,712, No. 5,
Compounds such as those disclosed in 369,000 and 5,464,737 are mentioned.

The antifoggant of the present invention may be added by any method such as a solution, a powder and a dispersion of solid fine particles. The dispersion of the solid fine particles is carried out by a known means for making fine (for example, a ball mill, a vibration ball mill, a sand mill, a colloid mill, a jet mill, a roller mill, etc.). When dispersing the solid fine particles, a dispersing aid may be used.

Although not required to practice the present invention,
It may be advantageous to add a mercury (II) salt as an antifoggant to the emulsion layer. Preferred mercury (II) salts for this purpose are
Mercury acetate and mercury bromide. The amount of mercury used in the present invention is preferably in the range of 1 nmol to 1 mmol, more preferably in the range of 10 nmol to 100 μmol, per 1 mol of silver applied.

The photothermographic material of the invention may contain benzoic acids for the purpose of increasing the sensitivity and preventing fog. The benzoic acids of the present invention may be any benzoic acid derivative, but examples of preferred structures include those described in U.S. Pat.
No. 9, No. 4, 152, 160, Japanese Patent Application No. 8-151242, No. 8-151241
And the compounds described in JP-A-8-98051 and the like. The benzoic acid of the present invention may be added to any part of the photosensitive heat-developable material, but it is preferable to add the benzoic acid to the layer having the photosensitive layer, and to add it to the organic silver salt-containing layer. Is more preferred. The benzoic acid of the present invention may be added at any time during the preparation of the coating solution, and when it is added to the organic silver salt-containing layer, it may be added at any time from the preparation of the organic silver salt to the preparation of the coating solution. It is preferable after salt preparation and immediately before application. The benzoic acid of the present invention may be added by any method such as powder, solution, and fine particle dispersion. Further, it may be added as a solution mixed with other additives such as a sensitizing dye, a reducing agent and a color tone agent. The benzoic acid of the present invention may be added in any amount, but is preferably from 1 micromol to 2 mol, more preferably from 1 mmol to 0.5 mol, per 1 mol of silver.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. be able to.

When a mercapto compound is used in the present invention, it may have any structure, but may be any of Ar-SM, Ar-SSA
Those represented by r are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring group or a condensed aromatic ring group having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring in these groups is benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, Triazine, pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazolinone. The heteroaromatic ring includes, for example, halogens (e.g., Br and Cl), hydroxy, amino, carboxy,
Alkyl (e.g. one or more carbon atoms, preferably 1-4
Having one carbon atom) and alkoxy (e.g.,
One having at least one carbon atom, preferably having 1 to 4 carbon atoms). Examples of the mercapto-substituted heteroaromatic compound include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole,
Mercapto-5-methylbenzimidazole, 6-ethoxy-
2-mercaptobenzothiazole, 2,2'-dithiobis-benzothiazole, 3-mercapto-1,2,4-triazole, 4,5
-Diphenyl-2-imidazolethiol, 2-mercaptoimidazole, 1-ethyl-2-mercaptobenzimidazole, 2-mercaptoquinoline, 8-mercaptopurine, 2-mercapto-4 (3H) -quinazolinone, 7-trifluoromethyl-
4-quinolinethiol, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate, 2-amino-5-mercapto-1,3,4 -
Thiadiazole, 3-amino-5-mercapto-1,2,4-triazole, 4-hydroxysil-2-mercaptopyrimidine, 2-mercaptopyrimidine, 4,6-diamino-2-mercaptopyrimidine, 2-mercapto-4-methyl Pyrimidine hydrochloride, 3-mercapto-5-phenyl-1,2,4-triazole,
Examples include 2-mercapto-4-phenyloxazole, but the present invention is not limited thereto.

The addition amount of these mercapto compounds is preferably in the range of 0.001 to 1.0 mol per mol of silver in the emulsion layer, more preferably 0.01 to 0.3 mol per mol of silver.
It is a molar amount.

In the photosensitive layer according to the present invention, a polyhydric alcohol (for example, US Pat.
Glycerin and diols of the type described in U.S. Pat. No. 0,404), fatty acids or esters described in U.S. Pat. Nos. 2,588,765 and 3,121,060, and silicone resins described in British Patent No. 955,061.

In the present invention, a hydrazine derivative may be used. When a hydrazine derivative is used in the present invention, the compound of the general formula (I) described in Japanese Patent Application No. 6-47961 is used. Specifically, compounds represented by I-1 to I-53 described in the same specification are used.

The following hydrazine derivatives are also preferably used.

Compounds represented by (Chemical Formula 1) described in JP-B-6-77138, specifically, compounds described on pages 3 and 4 of the same publication.
Compounds represented by formula (I) described in JP-B-6-93082, specifically, compounds 1 to 38 described on pages 8 to 18 of the same publication. Compounds represented by general formula (4), general formula (5) and general formula (6) described in JP-A-6-230497, specifically 25
Page, compound 4-1 to compound 4-10 described on page 26, compound 5-1 to 5-42 described on page 28 to page 36, and compound 6-1 to compound 6 described on page 39, page 40 -7. General formula (1) described in JP-A-6-289520
And a compound represented by the general formula (2), specifically,
Compounds 1-1) to 1-17) and 2-1) described on pages 5 to 7. Compounds represented by (Chemical Formula 2) and (Chemical Formula 3) described in JP-A-6-313936, specifically, compounds described on pages 6 to 19 of the same. Compounds represented by (Chemical Formula 1) described in JP-A-6-313951, specifically, compounds described on pages 3 to 5 of the same. JP 7-5610
And compounds I-1 to I-38 described in the same publication, specifically, on pages 5 to 10 of the same publication. JP 7-77
Compounds represented by the general formula (II) described in No. 783, specifically, compounds II-1 to II-102 described on pages 10 to 27 of the publication. Compounds represented by formulas (H) and (Ha) described in JP-A-7-104426, specifically, compounds H-1 to H-44 described on pages 8 to 15 of the same publication. A compound characterized by having an anionic group or a nonionic group forming an intramolecular hydrogen bond with a hydrogen atom of hydrazine in the vicinity of the hydrazine group described in Japanese Patent Application No. Hei 7-191007, particularly the general formula (A) , A general formula (B), a general formula (C), a general formula (D), a general formula (E), a compound represented by the general formula (F), specifically, the compound N- described in the same specification 1 to N-3
0. Compounds represented by the general formula (1) described in Japanese Patent Application No. 7-191007, specifically, compounds D-1 to D-55 described in the same specification.

When a hydrazine nucleating agent is used in the present invention, a suitable water-miscible organic solvent such as alcohols
(Methanol, ethanol, propanol, fluorinated alcohol), ketones (acetone, methyl ethyl ketone), dimethylformamide, dimethyl sulfoxide,
It can be used by dissolving it in methyl cellosolve or the like.

Further, by a well-known emulsification and dispersion method, an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone is used for dissolution, and mechanical An emulsified dispersion can be prepared and used. Alternatively, a powder of a hydrazine derivative can be dispersed in water by a ball mill, a colloid mill, or an ultrasonic wave by a method known as a solid dispersion method and used.

When a hydrazine-based nucleating agent is used in the present invention, the hydrazine-based nucleating agent may be used in any of a silver halide emulsion layer (photosensitive layer) on the side of the silver halide emulsion layer with respect to the support or another hydrophilic colloid layer. Although it may be added, it is preferably added to the silver halide emulsion layer or the hydrophilic colloid layer adjacent thereto.

The addition amount of the nucleating agent of the present invention is preferably from 1 to 10 mmol, more preferably from 10 to 5 mmol, most preferably from 20 to 5 mmol per mol of silver halide.

The photosensitive heat-developable material of the present invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. Any anti-adhesion material may be used as the surface protective layer. Examples of anti-adhesion materials include waxes, silica particles, styrene-containing elastomeric block copolymers (e.g., styrene-butadiene-styrene,
(Styrene-isoprene-styrene), cellulose acetate, cellulose acetate butyrate, cellulose propionate, gelatin, polysaccharides, and mixtures thereof.

In the present invention, the emulsion layer or the protective layer of the emulsion layer includes US Pat. Nos. 3,253,921, 2,274,782 and 2,52.
Light absorbing materials and filter dyes as described in 7,583 and 2,956,879 can be used. Also, dyes can be mordanted, for example, as described in US Pat. No. 3,282,699. The amount of the filter dye used is preferably such that the absorbance at the exposure wavelength is 0.1 to 3,
2-1.5 is particularly preferred.

In the emulsion layer or the protective layer of the emulsion layer in the present invention, a matting agent such as starch, titanium dioxide, zinc oxide, silica, US Pat. Nos. 2,992,101 and 2,701,245
Polymer beads, including beads of the type described in the above item, and the like. The matte degree of the emulsion surface may be any value as long as no stardust failure occurs, but the Beck smoothness is preferably 200 seconds or more and 10,000 seconds or less, particularly 300 seconds or more.
It is preferably 0000 seconds or less.

The photothermographic emulsion of the present invention is contained in one or more layers on a support. One layer must include the organic silver salt, silver halide, reducing agent (developer) and binder, and optional additional materials such as toning agents, coating aids and other auxiliaries. The two-layer configuration is that the first emulsion layer (usually the layer adjacent to the support) contains an organic silver salt and silver halide, and the second layer or both layers do not contain some other components. No. However, a two-layer construction comprising a single emulsion layer containing all components and a protective topcoat is also contemplated. It is also conceivable to have a first emulsion layer containing an organic silver salt, a second layer containing other components alone or distributed in both layers, and a three-layer structure further comprising a protective topcoat. The composition of the multicolor photothermographic material may include a combination of the two layers for each color,
Also, all components may be contained in a single layer as described in US Pat. No. 4,708,928. In the case of a multi-dye, multi-color photosensitive heat-developable photographic material, each emulsion layer generally has a functional or non-functional layer between the emulsion layers (photosensitive layer) as described in U.S. Pat. No. 4,460,681. By using a barrier layer, they are kept distinct from each other.

Various dyes can be used in the photosensitive layer of the present invention from the viewpoints of improving color tone and preventing irradiation. The dye used in the photosensitive layer of the present invention may be any dye, for example, pyrazoloazole dye, anthraquinone dye, azo dye, azomethine dye, oxonol dye, carbocyanine dye, styryl dye, triphenylmethane dye, indoaniline dye And indophenol dyes. Preferred dyes used in the present invention include anthraquinone dyes (for example, JP-A-5-341441).
No. 1-9, JP-A-5-165147
6-18 and 3-23-38, etc.), azomethine dyes (JP-A-5-3
No. 41441 No. 17-47), indoaniline dye
(For example, compounds 11 to 19 described in JP-A-5-289227,
And azo dyes (compounds 10 to 16 described in JP-A-5-341441). As a method for adding these dyes, any method such as a solution, an emulsion, a solid fine particle dispersion, and a state in which the dye is mordanted with a polymer mordant may be used. The amount of these compounds is determined by absorption of the object, it is preferably used in general photosensitive material 1 m ² per microgram least 1 gram or less.

In the present invention, the antihalation layer can be provided on the side farther from the light source than the photosensitive layer. The antihalation layer preferably has a maximum absorption in a desired wavelength range of 0.3 or more and 2 or less, more preferably an absorption of an exposure wavelength of 0.5 or more and 2 or less, and an absorption in a visible region after processing of 0.001 or more. It is preferably less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3.

When antihalation dyes are used in the present invention, such dyes have the desired absorption in the wavelength range,
Any compound may be used as long as it has a sufficiently low absorption in the visible region after the treatment and a desirable absorbance spectrum of the antihalation layer is obtained. For example, the following are disclosed, but the present invention is not limited thereto. As a single dye, JP-A-59-56458,
2-216140, 7-13295, 711432, U.S. Patent 5,38
No. 0,635, JP-A-2-68539, page 13, lower left column, line 1 to page 14, lower left column, line 9; JP-A-3-24539, page 14, lower left column, page 16, lower right column There are compounds of the following, as dyes that can be decolorized by treatment, JP-A-52-139136, JP-A-53-132334,
56-501480, 57-16060, 57-68831, 57-10
No. 1835, No. 59-182436, JP-A-7-36145, No. 7-199409
No., JP-B-48-33692, JP-B-50-16648, JP-B2-41734
Nos., U.S. Pat.Nos. 4,088,497, 4,283,487, 4,548,89
No. 6 and 5,187,049.

The photosensitive heat-developable material of the present invention has at least one photosensitive layer containing a silver halide emulsion (emulsion layer) on one side of a support, and a back layer (backing layer) on the other side. ), That is, a so-called one-sided photosensitive heat developing material.

In the present invention, the one-sided photosensitive heat-developable material is
A matting agent may be added for improving transportability. The matting agent is generally fine particles of an organic or inorganic compound insoluble in water. Any matting agent can be used, for example, U.S. Patent Nos. 1,939,213, 2,701,245, and 2,322,03
No. 7, 3,262,782, 3,539,344, 3,767,448, etc., the organic matting agent described in each specification, 1,260,772, the same
2,192,241, 3,257,206, 3,370,951, 3,52
Inorganic matting agents well-known in the art, such as inorganic matting agents described in the respective specifications such as 3,022 and 3,769,020, can be used. For example, specifically, examples of organic compounds that can be used as a matting agent include, as examples of water-dispersible vinyl polymers, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, and polystyrene. , Styrene-divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate, polytetrafluoroethylene, etc., examples of cellulose derivatives such as methylcellulose,
Examples of starch derivatives such as cellulose acetate, cellulose acetate propionate, carboxy starch, carboxynitrophenyl starch, urea-formaldehyde-
Gelatin hardened with a known hardener such as a starch reactant and hardened gelatin obtained by coacervate hardening to form fine capsule hollow particles can be preferably used. As examples of the inorganic compound, silicon dioxide, titanium dioxide, magnesium dioxide, aluminum oxide, barium sulfate, calcium carbonate, silver chloride desensitized by a known method, silver bromide, glass, and diatomaceous earth can be preferably used. The above matting agents can be used by mixing different types of substances as necessary. The size and shape of the matting agent are not particularly limited, and those having an arbitrary particle size can be used. In practicing the present invention, it is preferable to use one having a particle size of 0.1 μm to 30 μm. Further, the particle size distribution of the matting agent may be narrow or wide. On the other hand, since the matting agent greatly affects the haze of the coating film and the surface gloss, the particle size, shape, and particle size distribution can be changed as necessary during the preparation of the matting agent or by mixing a plurality of matting agents. preferable.

In the present invention, the matte degree of the back layer is preferably such that the Bekk smoothness is 250 seconds or less and 10 seconds or more, and more preferably 180 seconds or less and 50 seconds or more.

In the present invention, the matting agent is preferably contained in the outermost surface layer of the photosensitive heat-developable material, a layer functioning as the outermost surface layer, or a layer close to the outer surface, and acts as a so-called protective layer. It is preferably contained in a layer to be formed.

In the present invention, a suitable binder for the back layer is transparent or translucent, generally colorless, and includes natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, and poly (vinyl). (Alcohol), hydroxyethylcellulose, cellulose acetate, cellulose acetate butyrate, poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methylmethacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (Styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinylacetal) s (e.g., poly (vinylformal) and poly (vinylformal))
(Vinyl butyral)), poly (ester) s, poly (urethanes), phenoxy resin, poly (vinylidene chloride), poly (vinylidene chloride)
(Epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

In the present invention, the back layer preferably has a maximum absorption of 0.3 or more and 2 or less in a desired wavelength range.
More preferably absorption is 0.5 or more and 2 or less, and the absorption in the visible region after the treatment is preferably 0.001 or more and less than 0.5, and more preferably a layer having an optical density of 0.001 or more and less than 0.3. . Examples of the antihalation dye used in the back layer are the same as those of the antihalation layer described above.

A backside resistive heating layer as shown in US Pat. Nos. 4,460,681 and 4,374,921
e heating layer) can also be used in the photothermographic image system of the present invention.

A hardener may be used for each layer such as the photosensitive layer, the protective layer and the back layer of the present invention. Examples of hardeners include:
U.S. Pat.
Vinyl sulfone compounds described in No. 48 and the like are used.

In the present invention, a surfactant may be used for the purpose of improving coating properties and charging. As the surfactant, any surfactant such as nonionic, anionic, cationic, and fluorine can be used as appropriate. Specifically,
No. 62-170950, Fluoropolymer surfactants described in U.S. Pat.No. 5,380,644, JP-A-60-244945, JP-A-63-18
8135 No. fluorinated surfactants described in U.S. Pat.
No. 5,965, and the like, and polysiloxy acid-based surfactants described in JP-A-6-301140 and the like, and polyalkylene oxide and anionic surfactants.

Examples of the solvent used in the present invention include New Solvent Pocket Book (Ohm Co., 1994), but the present invention is not limited thereto. The solvent used in the present invention has a boiling point of 40 ° C or more and 180 ° C or more.
C. or lower is preferred.

Examples of the solvent of the present invention include hexane, cyclohexane, toluene, methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, ethyl acetate, 1,1,1-trichloroethane, tetrahydrofuran,
Triethylamine, thiophene, trifluoroethanol, perfluoropentane, xylene, n-butanol,
Phenol, methyl isobutyl ketone, cyclohexanone, butyl acetate, diethyl carbonate, chlorobenzene, dibutyl ether, anisole, ethylene glycol diethyl ether, N, N-dimethylformamide, morpholine,
Examples include propane sultone, perfluorotributylamine, and water.

The photographic emulsion for heat development in the present invention can be coated on various supports. Typical supports include polyester films, primed polyester films, poly (ethylene terephthalate) films, polyethylene naphthalate films, cellulose nitrate films, cellulose ester films, poly (vinyl acetal) films, polycarbonate films and related or resinous Including materials, as well as glass, paper, metal and the like. Flexible substrates, particularly coated with baryta and / or partially acetylated α-olefin polymers, especially polymers of C 2-10 α-olefins such as polyethylene, polypropylene, ethylene-butene copolymers A paper support is typically used.
The support may be transparent or opaque, but is preferably transparent.

The photosensitive heat-developable material of the present invention may contain an antistatic or conductive layer such as a soluble salt (eg, chloride, nitrate, etc.), a vapor-deposited metal layer, as described in US Pat. Nos. 2,861,056 and 3,206,312. It may have a layer containing an ionic polymer or an insoluble inorganic salt as described in US Pat. No. 3,428,451.

As a method for obtaining a color image by using the photosensitive heat-developable material in the present invention, there is a method described in JP-A-7-13295, page 10, left column, line 43 to 11 left column, line 40. Also,
British Patent 1,326,889 as stabilizer for color dye images
Nos., U.S. Pat.Nos. 3,432,300, 3,698,909, 3,574,62
No. 7, 3,573,050, 3,764,337 and 4,042,394
No.

The photothermographic emulsions of the present invention can be coated by various coating operations including dip coating, air knife coating, flow coating or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. If desired, two or more layers can be coated simultaneously by the methods described in U.S. Pat. No. 2,761,791 and British Patent 837,095.

Additional layers in the photothermographic material of the present invention, such as a dye-receiving layer for receiving a moving dye image, an opaque layer if reflective printing is desired, a protective topcoat layer and photothermographic techniques And a known primer layer. The light-sensitive material of the present invention is preferably capable of forming an image with only one light-sensitive material, and it is preferable that a functional layer necessary for image formation such as an image receiving layer does not become another light-sensitive material.

The photothermographic material of the present invention may be developed by any method, but is usually developed by elevating the temperature of the photothermographic material exposed imagewise. The preferred development temperature is 80 to 250 ° C, more preferably 100 to 250 ° C.
140 ° C. The development time is preferably from 1 to 180 seconds,
0 to 90 seconds is more preferred.

The photosensitive heat-developable material of the present invention may be exposed by any method, but a laser beam is preferred as an exposure light source. As the laser beam according to the present invention, a gas laser, a YAG laser, a dye laser, a semiconductor laser and the like are preferable. Further, a semiconductor laser and a second harmonic generation element can be used.

The heat-developable photosensitive material of the present invention has a low haze upon exposure and tends to cause interference fringes. As this interference fringe generation prevention technology, a technology of obliquely entering a laser beam as disclosed in Japanese Patent Application Laid-Open No. HEI 5-113548 or a photosensitive heat developing material, and a technology disclosed in WO95 / 31754 and the like are disclosed. Methods using a multi-mode laser are known, and it is preferable to use these techniques.

Exposure of the photosensitive heat-developable material of the present invention
SPIE vol.169 Laser Printing 116-128 pages (1979), JP-A-4-51043, WO95 / 31754, etc. Is preferred.

[0112]

Hereinafter, the present invention will be described with reference to Examples.
The present invention is not limited to these.

Example 1 (1) Preparation of silver halide emulsion (Preparation of silver halide grains A) 22 g of phthalated gelatin and 30 mg of potassium bromide were dissolved in 700 ml of water, and the pH was adjusted to 5.0 at a temperature of 40 ° C. After that, an aqueous solution containing 18.6 g of silver nitrate 159 m
l and an aqueous solution of potassium bromide were added over 10 minutes by the control double jet method while maintaining pAg of 7.7. Then, 476 ml of an aqueous solution containing 55.4 g of silver nitrate, 8 μmol / liter of dipotassium hexachloride iridate and 1 part of potassium bromide were added.
The aqueous solution containing mol / liter was added over 30 minutes by the control double jet method while maintaining the pAg at 7.7. Thereafter, the pH was lowered to perform coagulation sedimentation and desalting treatment, and 0.1 g of phenoxyethanol was added to adjust to pH 5.9 and pAg 8.0. The obtained particles were cubic particles having an average particle size of 0.07 μm, a variation coefficient of the projected area diameter of 8%, and a (100) plane ratio of 86%.

The temperature was adjusted to 6 with respect to the prepared silver halide grains A.
Raise the temperature to 0 ° C and use sodium thiosulfate 85μ per mole of silver.
Mole, 2,3,4,5,6-pentafluorophenyldiphenylphosphine selenide, 11 μmol, 2 μmol of the following tellurium compound 1, 3.3 μmol of chloroauric acid, thiocyanic acid
230 μmol was added and aged for 120 minutes.

Thereafter, the temperature was changed to 50 ° C., and the following sensitizing dye A and 2.5 × 10 ^-4 mol of the following sensitizing dye A and 4 × 10 ^-3 mol of the following compound B were added to silver halide with stirring, and after 30 minutes, The mixture was rapidly cooled to 30 ° C. to complete the preparation of silver halide grains A.

[0116]

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[0117]

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(Preparation of silver halide grains B) Except that the temperature at the time of silver halide grain formation was changed from 40 ° C to 32 ° C, grains were formed in the same manner as silver halide grains A, and finally the average grain size was adjusted. Cubic grains having a diameter of 0.045 μm, a variation coefficient of the projected area diameter of 15%, and a (100) face ratio of 80% were obtained. The obtained grains were chemically sensitized in the same manner as in the silver halide emulsion A, and the sensitizing dye A and the compound B were added to complete the preparation of the silver halide B.

(Preparation of silver halide grains C) The sensitizing dye to be added after the formation of silver halide grains was added to the following sensitizing dye C, and the addition amount was 6.5 × 10 ^-4 mol per mol of silver halide. A silver halide emulsion C was prepared in the same manner as in the silver halide emulsion A except for the change.

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The effective sensitivities of the silver halide grains A, B, and C were determined from characteristic curves obtained by performing the same processing as the photographic performance evaluation described below on the coating samples Nos. 1, 2, and 8 described below. Was. When the sensitivity is expressed as a relative sensitivity when the sensitivity of sample No. 1 is set to 100, the silver halide grain A is 10%.
0, silver halide grains B were 41, and silver halide grains C were 40.

(2) Preparation of Organic Acid Silver Crystalline Dispersion 40 g of behenic acid, 7.3 g of stearic acid and 400 ml of water were heated at 90 ° C.
For 15 minutes, add 200 ml of 1N-NaOH over 15 minutes,
61 ml of a 1N aqueous nitric acid solution was added, and the temperature was lowered to 50 ° C. Then 1N
124 ml of an aqueous silver nitrate solution was added over 2 minutes, and the mixture was stirred for 30 minutes. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the conductivity of the filtrate reached 30 μS / cm. The solid content thus obtained was handled as a wet cake without drying, and 12 g of polyvinyl alcohol and 150 ml of water were added to a wet cake equivalent to 34.8 g of dry solid content and mixed well to form a slurry. Prepare 840 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and use a dispersing machine (1 / 4G sand grinder mill:
Dispersion for 5 hours by electron microscope and preparation of microcrystalline dispersion of silver salt of organic acid as needle-like particles having average minor axis of 0.04 μm, average major axis of 0.8 μm, and projected area variation coefficient of 30% by electron microscope observation. Finished.

(3) Preparation of Material Solid Fine Particle Dispersion Tetrachlorophthalic acid, 4-methylphthalic acid, 1,1-
Bis (2-hydroxy-3,5-dimethylphenyl)-
Solid fine particle dispersions of 3,5,5-trimethylhexane, phthalazine, and tribromomethylphenylsulfone were prepared. 0.81 g of hydroxypropylmethylcellulose and 94.2 ml of water were added to tetrachlorophthalic acid, and the mixture was stirred well and left as a slurry for 10 hours. Thereafter, 100 g of zirconia beads having an average diameter of 0.5 mm was prepared, placed in a vessel together with the slurry, and dispersed in the same dispersing machine as used for preparing the silver salt of organic acid microcrystal dispersion for 5 hours to prepare tetrachlorophthalic acid. Was obtained. 70% by weight of the particle diameter was 1.0 μm or less. For other materials, the amount of the dispersant used and the dispersion time were changed to obtain the desired average particle size, and solid fine particle dispersions were obtained for each material.

(4) Preparation of Coating Solution for Emulsion Layer To 500 g of LACKSTAR 3307B (SBR latex manufactured by Dainippon Ink and Chemicals, Inc.) as a polymer latex, an organic silver microcrystal dispersion (silver 1 Mole equivalent)
And the following materials were added with good stirring to obtain an emulsion coating solution.

Silver halide grains 10 mol% of silver halide / equivalent to organic acid silver 10 g of tetrachlorophthalic acid 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethyl Hexane 98g Phthalazine 9.2g Tribromomethylphenylsulfone 12g 4-Methylphthalic acid 14g

Incidentally, Luck Star 3307B is a latex of a styrene-butadiene copolymer, and the average particle size of the dispersed particles is about 0.1 to 0.15 μm. Also,
The equilibrium water content determined as described below was 0.6% by weight.

As shown in Table 1, silver halide grains A, B, and C were used alone, or those obtained by mixing and adjusting the gradation of the silver halide grains were adjusted to have a total silver halide content of an organic acid. It was added in an amount of 10 mol% per mol of silver.

(5) Preparation of Coating Solution for Emulsion Surface Protective Layer The following surfactant A was added in an amount of 0.26 to 10 g of inert gelatin.
g, 0.09 g of the following surfactant B, 0.9 g of silica fine particles (average particle size 2.5 μm), 0.3 g of 1,2- (bisvinylsulfonylacetamide) ethane, and 64 g of water were added to form a surface protective layer.

[0129]

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(6) Preparation of Coloring Agent Dispersion To 35 g of ethyl acetate, 2.5 g and 7.5 g of the following compounds 1 and 2 were added and dissolved by stirring. 10% by weight of polyvinyl alcohol previously dissolved in the liquid
50 g of the solution was added and stirred with a homogenizer for 5 minutes. Thereafter, the ethyl acetate was volatilized by removing the solvent, and finally diluted with water to prepare a color former dispersion.

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(7) Preparation of Back Surface Coating Solution For 30 g of polyvinyl alcohol, 50 g of the previously prepared colorant dispersion, 20 g of the following compound, 250 g of water and Sildex H121 (Spherical silica manufactured by Dokai Chemical Co., Ltd., average size (1.8 μm) was added to obtain a back surface coating solution.

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(8) Preparation of Emulsion Layer Coating Sample The emulsion layer coating solution prepared as described above was coated on a 175 μm polyethylene terephthalate support tinted with a blue dye so that silver was 1.9 g / m ^2. A coating solution for an emulsion surface protective layer was applied onto the emulsion coating layer so that the coating amount of gelatin was 1.8 g / m ² . After drying, the back surface coating solution was coated on the surface opposite to the emulsion layer so as to have an optical density of 0.7 at 660 nm,
Application samples Nos. 1 to 11 were prepared. The equilibrium water content of the binder used in the emulsion layer was determined as follows.

<Equilibrium Water Content> The solution (or dispersion) of the polymer used for the emulsion layer was applied on a glass plate and dried at 50 ° C. for 1 hour to obtain a polymer model film having a thickness of about 100 μm. The polymer model film thus obtained was peeled from the glass plate and conditioned in an atmosphere at 25 ° C. and 60% RH for 3 days, and the weight (W ₁ ) was measured. Then, the polymer model film was placed in a vacuum at 25 ° C. for 3 days, immediately put into a weighing bottle of which weight was known, and the weight (W ₀ = W ₃ −W ₂ ) was measured (W ₃ is the weight of the polymer model film and the weight of the polymer model film). the weight of the bottle, W ₂ is the weight of the weighing bottle). Using W ₀ and W ₁ , the water content was determined by the following equation. Equilibrium water content at 25 ° C. and 60% RH = ｛(W ₁ −W ₀ )
/ W ₀ ｝ × 100 (%)

(9) Evaluation of Coated Sample (Evaluation of Photographic Performance) Coating was performed with a laser sensitometer equipped with a 647 nm Kr laser (maximum output: 500 mW) at an oblique angle of 30 degrees with respect to the normal line while changing the exposure amount. After exposing the sample, the coated sample was heat-developed at 120 ° C. for 20 seconds, and the density of the obtained image was measured. The resulting data was plotted with the logarithm of the exposure (log E) on the horizontal axis and the scattered light photographic density (D) on the horizontal axis to create a photographic characteristic curve. Table 1 shows the gamma value (G) of the inclination of the tangent line (tan θ when the angle between this tangent line and the horizontal axis is θ) and the maximum value of the optical density at Dmax at the optical density D = 1.2 on the characteristic curve. It was shown to.

(Evaluation of Silver Tone) The silver tone of the image portion of the obtained sample was visually evaluated.

(Evaluation of Photo-Irradiated Image Storage Property) A sample of a photosensitive material exposed and developed in the same manner as in the evaluation of photographic properties was attached to the inside of a glass window exposed to direct sunlight, and the state of the image after being left for one month is shown below. Was visually evaluated according to the following criteria. …: Almost no change was observed. …: Slight change in color tone but not bothersome. Δ: Partial discoloration of the image is present but practically acceptable. ×: The minimum density (Dmin) is discolored, and the image area is discolored and the density change is not large.

(Evaluation of Storage Property of Dark Thermal Image) A sample of a photosensitive material which was exposed and developed in the same manner as in the evaluation of photographic properties was left at 40 ° C. for one month under light-shielded conditions. It was visually evaluated. …: Almost no change was observed. …: Slight change in color tone but not bothersome. Δ: Partial discoloration of the image is present but practically acceptable. ×: The minimum density (Dmin) is discolored, and the image area is discolored and the density change is not large.

(Evaluation of Thermal Development Unevenness)
Prepare the sample with a size of cm x 43 cm, adjust the output so that the optical density becomes 1.2 using the laser sensitometer used in the photographic evaluation, uniformly expose the entire sample, and then apply the coated sample. The image obtained by heat development at 120 ° C. for 20 seconds was visually evaluated for density unevenness on a 5-point scale. 4 or more is a practically acceptable level, and 3 or less is a practically unusable level.

Table 1 shows the evaluation results. As is clear from Table 1, samples Nos. 5 to 7 and No.
It is understood that Samples Nos. 10 and 11 have little heat development unevenness and are excellent in color tone and image preservability.

[0142]

[Table 1]

[0143]

According to the present invention, heat development unevenness is small,
A photothermographic material having excellent image storability with little change in photographic characteristics per unit area, such as good color tone, can be obtained.

Claims (3)

[Claims] 1. A photosensitive heat-developable material having at least a photosensitive silver salt, an organic silver salt, a reducing agent and a binder on a support, and having at least one photosensitive layer containing the photosensitive silver salt, Gamma at an optical density of 1.2 or more in a photographic characteristic curve (curve in which optical density is plotted against a common logarithm of exposure energy) obtained by exposure and heat development. A photosensitive heat-developable material having a value of 2.5 or less. 2. The main binder of the photosensitive layer is 25.degree.
The photosensitive layer according to claim 1, wherein the photosensitive layer is formed of a polymer having an equilibrium water content at 2% RH of 2% by weight or less, and the photosensitive layer is formed of a solvent in which 30% by weight or more of a solvent is water. Photothermographic material. 3. The photosensitive photothermographic material according to claim 1, wherein the same photosensitive layer contains at least two kinds of photosensitive silver salts having different effective sensitivities.