JP2001109099A - Heat developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat developable photosensitive material, particularly a heat developable photosensitive material for printing, minutely a heat developable photosensitive material having enhanced uniformity of image density in heat development and excellent in image stability. SOLUTION: The heat developable photosensitive material has a photosensitive layer containing silver halide and an organic silver salt on the substrate and a protective layer on the photosensitive layer. The photosensitive material is processed with a heat processing machine having a means of carrying out reheating at a lover temperature than that of a developed part after heat development. The grain size distribution of the organic silver salt is of monodisperse system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photothermographic material which provides stable developability.

[0002]

2. Description of the Related Art Conventionally, in the field of printing plate making and medical care,
Waste liquids resulting from wet processing of photosensitive materials have become a problem in terms of workability, and in recent years, reduction of processing waste liquids has been strongly desired from the viewpoint of environmental conservation and space saving. Therefore, there has been a need for a technique relating to a photothermographic material capable of performing efficient exposure by a laser image setter or a laser imager and forming a high-resolution and clear black image. As techniques for this purpose, silver halide photosensitive materials which form a photographic image by heat treatment are known, and these are described, for example, in US Pat. Nos. 3,152,904 and 3,45.
7,075 and D.C. Morgan and B.A.
"Thermally Processed Silver System" by Shelly
Silver Systems), Imaging
Processes and Materials (Imagin
g Processes and Material
s) Neblette Eighth Edition, Sturge
e), V.I. Walworth, A .;
Shepp, 2nd page, 1969, etc. Such a photothermographic material (hereinafter, also simply referred to as a “photosensitive material”) comprises a reducible silver source (eg, an organic silver salt), a catalytically active amount of a photocatalyst (eg, a silver halide) and a reducing agent, which is usually an organic binder matrix. It is contained in a dispersed state. The photothermographic material is stable at room temperature, but generates silver by an oxidation-reduction reaction between a reducible silver source (acting as an oxidizing agent) and a reducing agent when heated to a high temperature after exposure. This oxidation-reduction reaction is promoted by the catalytic action of the latent image generated by the exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas and results in the formation of an image.

However, heat-developable photosensitive materials are subjected to development processing by applying heat, and there is a serious problem that the density of an obtained image fluctuates due to a minute change in temperature during thermal development and density unevenness occurs. there were.

Further, US Pat. No. 5,352,863,
Nos. 5,665,257 and 5,849,388
No. 5,869,806 and 5,869,80
Nos. 7 and 5,895,592 disclose the heat development method, but these conventional techniques have a drawback that the resulting density and the occurrence of density unevenness cannot be controlled, and image defects occur. In the photothermographic material,
The temperature distribution from the high-temperature development state to the stop of the development is not uniform, and so-called fogging may occur due to the light radiated after the discharge. Therefore, stabilization of an image to be formed has been desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object the purpose of the present invention.
In particular, it is an object of the present invention to provide a photothermographic material for printing, and more specifically, to provide a photothermographic material having high image density uniformity and excellent image stability in a heat development process.

[0006]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
This has been achieved by the following configuration.

[0007] 1. In a photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer thereon, a photothermographic processor having means for reheating at a lower temperature than the developing section after thermal development. A photothermographic material which has been processed and has a monodisperse particle size distribution of the organic silver salt.

[0008] 2. In a photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer thereon, a photothermographic processor having means for reheating at a lower temperature than the developing section after thermal development. The specific heat capacity of the main binder treated and contained in the protective layer is from 1.3 to 2.
A photothermographic material characterized by 1 kJ / (kg · K).

3. In a photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer thereon, a photothermographic processor having means for reheating at a lower temperature than the developing section after thermal development. A photothermographic material which has been treated and has a surface roughness Ra of 50 to 150 nm.

[0010] 4. 4. The photothermographic material according to any one of items 1 to 3, wherein the photosensitive layer and the protective layer are applied by an extrusion die coater.

That is, as a result of intensive research, the present inventors have found that cooling the photothermographic material after development stepwise and uniformly over a certain temperature range is extremely effective against density fluctuations and density unevenness. It has been found that the development stability can be improved by setting the part to the specified conditions, and furthermore, the image stability can be further improved by providing the photothermographic material with specific physical properties in combination with the development method. Was.

Hereinafter, the present invention will be described in detail.

The method of processing a photothermographic material according to the present invention is characterized in that the photothermographic material is subjected to a heat development process by sequentially passing through a preheating section, a development section, a reheating section and a cooling section.

The thermal developing method and the processing apparatus used in the present invention comprise a preheating section, a developing section, a reheating section and a cooling section.

As a heating means for the heat development, a mode having a conductive heating element layer, for example, a heating element described in JP-A-61-145544 such as a halogen lamp and a sheet heater can be used. As a specific form, 1) a method in which it is placed in an oven at a constant temperature for a predetermined time, 2) a method of conveying the inside of the oven kept at a constant temperature at a constant speed,
3) There is no particular limitation as long as it is a method of contacting a medium (metal roller, silicon rubber, urethane rubber, paper, fluorinated medium, etc.) heated to a certain temperature for a predetermined time. In the present invention, a horizontal transfer system and a conveyor system are preferable in the forms 1) and 2).

The temperature of the preheating section is preferably lower than the developing temperature of the developing section by 5 ° C. or more. The temperature range is preferably from 100 to 120 ° C, more preferably from 100 to 115 ° C. The processing time of the remaining heat section is preferably 1 to 60 seconds, more preferably 5 to 50 seconds.

The preferred temperature range for the developing section is 10
0-150 degreeC is preferable and 100-140 degreeC is more preferable. In the present invention, the preferable processing time range of the developing section is preferably 3 to 30 seconds, more preferably 5 to 30 seconds. In performing such thermal development, it is preferable not to apply tension to the photothermographic material, but there is no particular limitation as long as it is 10 kg or less. However, if the tension is excessively applied, the dimensions of the light-sensitive material change, which causes a problem in the form and requires attention.

The present invention is characterized in that a reheating section is provided for reheating at a lower temperature than the developing section after the thermal development. The temperature at which the reheating section is lower than the developing section is a temperature lower by 5 to 40 ° C, and more preferably a temperature lower by 5 to 30 ° C. The processing time of the reheating unit is preferably 0.1 to 30 seconds, more preferably 0.3 to 15 seconds. As the reheating means, as described above, a mode having a conductive heating element layer, a halogen lamp, a sheet heater, and the like are disclosed in JP-A-61-14554.
The heating element described in No. 4 can be used. There is no particular limitation as long as it can be brought into contact with a medium (metal roller, silicon rubber, urethane rubber, paper, fluorinated medium, etc.) heated to a certain temperature for a predetermined time. In the present invention, a roller having a built-in sheet heater or heating element is preferable. In the case of a roller, an opposing roller is preferable, and one or more and three or less are preferable. The heating element may be incorporated into only one side or both sides of the roller, and there is no particular limitation.

The cooling unit can be used without particular limitation as long as it can rapidly cool, such as air from a cooling fan, contact with a cooling plate, contact with a metal roller, and the like. It is preferable that the temperature of the photothermographic material discharged from the development processor is 50 ° C. or less at the time when the photothermographic material leaves the apparatus. Exposure to light while the temperature is high causes fogging.

The photothermographic material according to the first aspect is characterized in that the particle size distribution of the organic silver salt contained in the photosensitive layer is monodisperse. The organic silver salt particles used in the present invention will be described in detail.

In the present invention, the organic silver salt is a reducible silver source, and a silver salt of an organic acid or a heteroorganic acid containing a reducible silver ion source, especially a long chain (10 to 30, preferably 15 to 25, And the nitrogen-containing heterocycle is preferred. Organic or inorganic silver salt complexes wherein the ligand has a total stability constant for silver ions of 4.0 to 10.0 are also useful. Examples of suitable silver salts are Research
h Disclosure Nos. 17029 and 29963
And salts of: organic acid salts such as gallic acid, oxalic acid, behenic acid, arachidic acid, stearic acid, palmitic acid, lauric acid and the like; silver carboxyalkylthiourea salts; For example, 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea and the like; a silver complex of a polymer reaction product of an aldehyde and a hydroxy-substituted aromatic carboxylic acid, for example, Aldehydes (formaldehyde,
Acetaldehyde, butyraldehyde, etc.), hydroxy-substituted acids (eg, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid), silver salts or complexes of thiones (eg, 3- (2- (Carboxyethyl) -4-hydroxymethyl-4-thiazoline-2
-Thione, 3-carboxymethyl-4-thiazoline-2
-Thione), imidazole, pyrazole, urazole,
1,2,4-thiazole and 1H-tetrazole, 3-
Complexes or salts of silver and a nitrogen acid selected from amino-5-benzylthio-1,2,4-triazole and benzotriazole; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides. Preferred silver sources are silver behenate, silver arachidate, silver stearate and silver palmitate.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, but a forward mixing method, a reverse mixing method, a simultaneous mixing method, etc. are preferably used. Further, it is also possible to use a controlled double jet method as described in JP-A-9-127463. Specifically, after adding an alkali metal salt (for example, sodium hydroxide, potassium hydroxide, etc.) to an organic acid to prepare an organic acid alkali metal salt soap (for example, sodium behenate, sodium arachidate, etc.),
Silver nitrate is added to the soap to produce organic silver salt crystals. At that time, silver halide grains may be mixed,
The above series of reaction steps need to be performed while stirring sufficiently using a suitable stirring member so that the inside of the reaction tank becomes uniform.

The organic silver salt particles used in the present invention are characterized in that the particle size distribution is monodisperse, whereby an image having a high density can be obtained. As the monodispersion, the degree of monodispersion is preferably 1% to 30%. Here, the monodispersion is defined as a degree of monodispersion obtained by the following equation.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100 In the present invention, the average particle size of the organic silver salt is preferably 1 μm or less. The average particle size of the organic silver salt refers to the diameter of a sphere equivalent to the volume of the organic silver salt particles when the particles of the organic silver salt are, for example, spherical, rod-shaped, or tabular particles.
The average particle size is preferably 0.01 μm to 0.8 μm, particularly preferably 0.05 μm to 0.5 μm. Further, in the organic silver salt, the tabular grains preferably have 60% or more of the total organic silver. In the present invention, the tabular grains mean those having an aspect ratio (abbreviated as AR) of 3 or more, which is a ratio between the average particle diameter and the thickness, that is, the following formula.

AR = average particle diameter (μm) / thickness (μm) The method for obtaining the organic silver salt particles having the above-mentioned monodispersity is not particularly limited. Optimization of various conditions such as a mixing state when silver nitrate is added to the soap is effective.

It is preferable that the organic silver salt particles used in the present invention are preliminarily dispersed together with a binder, a surfactant and the like, if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. The pressure applied during the dispersion pulverization at this time is preferably 28 MPa or more, more preferably 56 MPa or more, and particularly preferably 70 MPa to 150 MPa.

The above preliminary dispersion includes, for example, an anchor type,
A general stirrer such as a propeller type, a high-speed rotation centrifugal radiation stirrer (dissolver), and a high-speed rotation shear stirrer (homomixer) can be used. Further, as the media dispersing machine, for example, a ball mill, a planetary ball mill, a rolling mill such as a vibration ball mill, a bead mill as a medium stirring mill, an attritor, and other basket mills can be used, and as a high-pressure homogenizer, For example, various types such as a type that collides with a wall, a plug, or the like, a type in which a liquid is divided into a plurality of pieces and then the liquids collide with each other at high speed, and a type in which a thin orifice passes through can be used.

In the apparatus used for dispersing the organic silver salt particles used in the present invention, as a material of a member that the organic silver particles come into contact with, for example, ceramics such as zirconia, alumina, silicon nitride, boron nitride, etc. It is preferable to use diamond and / or diamond, and particularly preferable to use zirconia.

The binder concentration at the time of performing the above dispersion,
By optimizing the predispersion method, the operating conditions of the disperser, the number of times of dispersion, etc., the organic silver salt particles having a monodispersity of the present invention can be obtained.

Next, in the photothermographic material according to the present invention, the specific heat capacity of the main binder contained in the protective layer is 1.3 to 2.1 kJ / (kg · K). And more preferably 1.3 to 1.7 kJ / (kg ·
K). By setting the specific heat capacity of the protective layer to the value of the present invention, the flow of heat from the surface of the photothermographic material is stabilized, and the image performance is improved. The specific heat capacity value can be achieved by appropriately selecting a known binder or by combining them.

Binders suitable for the photothermographic material of the present invention are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic, and poly (arabic). (Vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid) Copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (ester) Kind, poly ( Urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxides),
Poly (carbonate) s, poly (vinyl acetate),
There are cellulose esters and poly (amides). It may be hydrophilic or hydrophobic. Preferred binders include
Examples thereof include polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, polycarbonate, polyacrylic acid, and polyurethane. Among them, polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, and polyester are particularly preferably used.

As another preferred binder, a binder which is soluble or dispersible in an aqueous solvent (aqueous solvent),
It is a polymer having an equilibrium water content of 2% by weight or less at 60 ° C. and 60% RH. When such a polymer is used, a photosensitive layer can be formed using a water solvent containing 30% by weight or more of water as a coating solvent. Examples of such a polymer include an acrylic resin, a polyester resin, a polyurethane resin, a vinyl chloride resin, a vinylidene chloride resin, a rubber-based resin (for example, S
(BR resin and NBR resin), vinyl acetate resin, polyolefin resin, polyvinyl acetal resin and the like.

The specific heat capacity of the binder is, for example,
It is described in Chapter 9, Thermal Properties, pages II-243, etc. of Chemical Handbook, Basic Edition II (1984), edited by The Chemical Society of Japan, or can be determined by measurement using the method described in JIS K 7123. it can.

The main binder in the present invention refers to a binder constituting at least 50% of the total binder in the protective layer.

The binder used in the protective layer may be the same as or different from the binder used in the photosensitive layer and other non-photosensitive layers.

The binder amount of the protective layer is 0.5 to 8 g / m
² , more preferably 1.0 to 6
g / m ² .

The photothermographic material of the invention according to claim 3 is characterized in that the protective layer has a surface average roughness Ra (also referred to as a center line average roughness) of 50 to 150 nm.
Preferably it is in the range of 70 to 120 nm. Surface average roughness Ra (roughness av) used in the present invention.
“erage” is a value obtained by decomposing a measured two-dimensional surface into M × N pixels and calculating an average of M × N pixels for roughness of each pixel.

The three-dimensional surface roughness meter used in the present invention includes, for example, a scanning electron microscope equipped with a plurality of detectors such as ERA-8000FE manufactured by Elionix, and a surface roughness such as an atomic force microscope (AFM). Is a numerical value that can be output as a numerical value.
It is preferable to use a non-contact type three-dimensional surface roughness meter utilizing optical interference represented by the ST / PLUS type.

In the photothermographic material of the present invention, the means for obtaining a predetermined surface average roughness is not particularly limited, but the kind of the matting agent used in the protective film, the filling amount in the protective film, and the amount of the protective film. It can be achieved by appropriately selecting and optimizing a film thickness, a coating solution viscosity, a coating method, drying conditions, and the like.

In the photothermographic material of the present invention, the protective layer on the photosensitive layer side preferably contains a matting agent. The matting agent has a weight ratio of 0.1 to all binders on the photosensitive layer side.
It is preferable to contain 5 to 30%.

The material of the matting agent preferably used in the photothermographic material of the present invention may be either an organic substance or an inorganic substance. For example, as the inorganic substance, Swiss Patent No. 330,
No. 158, French Patent No. 1,296,9
No. 95, British Patent No. 1,173,1
No. 81 or other alkaline earth metals or carbonates such as cadmium and zinc can be used as matting agents.
Examples of organic substances include starch described in U.S. Pat. No. 2,322,037, starch derivatives described in Belgian Patent No. 625,451 and British Patent No. 981,198, and Japanese Patent Publication No. 44-3643. Polyvinyl alcohol as described,
Polystyrene or polymethacrylate described in Swiss Patent No. 330,158 and the like, US Pat. No. 3,079,
Organic matting agents such as polyacrylonitrile described in US Pat. No. 257 and the like and polycarbonate described in US Pat. No. 3,022,169 and the like can be used.

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

The matting agent preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm.
m. The coefficient of variation of the particle size distribution is 5
0% or less, more preferably 40%
Or less, particularly preferably 30% or less.

Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

Coefficient of variation = (standard deviation of particle size) / (average value of particle size) × 100 The matting agent can be contained in any constituent layer, but is preferably a constituent layer other than the photosensitive layer. In the photothermographic material of the invention, the protective layer on the photosensitive layer side preferably contains a matting agent. That is, a matting agent is provided on the surface of the photosensitive material in order to obtain a desired surface average roughness. The method of adding the matting agent may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed before the drying is completed after the coating solution is applied. When a plurality of types of matting agents are added, both methods may be used in combination.

The matting agent is preferably contained in a weight ratio of 0.5 to 30% based on all binders on the photosensitive layer side.

Coating methods used in the production of the photothermographic material include reverse rolls, gravure rolls, air doctor coaters, blade coaters, air knife coaters, and the like.
Squeeze coaters, impregnation coaters, bar coaters, transfer roll coaters, kiss coaters, cast coaters or spray coaters, extrusion coaters, and the like are known.In the present invention, the formation of a constituent layer on a support is performed by an extrusion die coater. It is characterized by performing.

When a protective layer is provided on the photosensitive layer, the coating and drying may be repeated for each layer. However, it is preferable that the coating and drying are performed by a wet-on-wet method.

In the multi-layer coating in the wet-on-wet method, the upper layer is coated while the lower layer is kept wet, so that the adhesiveness between the upper and lower layers is improved and the upper layer is coated. Good physical properties of the surface. As a result, the requirements in the printing field where image stability is required are satisfied.

The viscosity of the coating solution of each constituent layer is preferably 200 cP or more and 500 cP or less. 200 cP
Below, unevenness may occur depending on the conditions. Conversely, when it is 500 cP or more, the fluidity of the coating liquid decreases, the coatability decreases, and as a result, each physical property value according to the present invention is obtained. Becomes difficult. Within this range, the fluidity of the coating liquid is good and coating unevenness is unlikely to occur, so that coating can be performed uniformly under any conditions. The viscosity of the coating solution was measured using a B-type viscometer manufactured by Tokyo Keiki Co., Ltd.

The photothermographic material according to the present invention contains a silver halide, a reducing agent, a high contrast agent and the like in addition to the organic silver salt.

The photosensitive layer of the photothermographic material of the present invention contains silver halide particles functioning as an optical sensor. The silver halide grains preferably have a small average grain size, more preferably 0.1 μm or less, more preferably 0.01 to 0.1 mm, in order to suppress white turbidity after image formation and obtain good image quality. 1 μm, especially 0.02 to 0.0
8 μm is preferred. The term "grain size" as used herein refers to the length of a ridge of a silver halide grain when the silver halide grain is a cubic or octahedral so-called normal crystal. In the case of non-normal crystals, for example, in the case of spherical, rod-shaped or tabular grains, the diameter refers to the diameter of a sphere equivalent to the volume of silver halide grains.

The silver halide grains are preferably monodispersed. The term “monodispersion” as used herein has the same meaning as the monodispersion described for the organic silver salt, and indicates a monodispersity of 40% or less, preferably 30% or less, more preferably 20% or less.
% Or less.

The shape of the silver halide grains is not particularly limited, but the ratio occupied by the Miller index [100] plane is preferably high, and this ratio is 50% or more, and more preferably 7%.
It is preferably at least 0%, particularly preferably at least 80%. The ratio of the Miller index [100] plane is determined by the T.M. Tani, J .; Imaging Sci. , 29,
165 (1985).

In the present invention, one of the preferable shapes of silver halide is tabular grains. As used herein, the term “tabular grains” refers to an aspect ratio where the square root of the projected area is r μm and the thickness in the vertical direction is h μm = r /
h means 3 or more. Among them, the aspect ratio is preferably 3 or more and 50 or less. The particle size is 0.1 μm
Or less, more preferably 0.01 to 0.08
μm is preferred. These are disclosed in US Pat. No. 5,264,33.
No. 7, No. 5,314,798, No. 5,320,958
The target tabular grains can be easily obtained.

The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide. The photographic emulsion used in the present invention is P.I. Glafkids Chimie et
Physique Photographique (P
aul Montel, 1967); F. D
uffin Photographic Emulsi
on Chemistry (The Focal Pr
ess, 1966); L. Zelikman
et. , Al. , Making and Coatin
g Photographic Emulsion (T
he Focal Press, 1964) and the like. That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and a method of reacting a soluble silver salt with a soluble halide may be any one of a one-sided mixing method, a double-sided mixing method, a combination thereof and the like. Good.

The silver halide may be added to the organic silver salt dispersion by any method, in which case the silver halide is arranged close to the reducible silver source. Further, the silver halide may be prepared by converting a part or all of silver in the organic acid silver by a reaction between the organic acid silver and a halogen ion into silver halide, or preparing the silver halide in advance. In advance, this may be added to a solution for preparing an organic silver salt, or a combination of these methods is possible, but the latter is preferred.

The silver halide is preferably contained in an amount of 0.75 to 30% by weight based on the organic silver salt.

The silver halide used in the present invention preferably contains metal ions or complex ions belonging to Groups 6 to 11 of the periodic table. These metals include
W, Fe, Co, Ni, Cu, Ru, Rh, Pd, R
e, Os, Ir, Pt, and Au are preferred. These metals can be introduced into the silver halide in the form of a complex.

In the present invention, the transition metal complex is preferably a six-coordinate complex represented by the following general formula.

In the formula [ML ₆ ] ^m , M is a transition metal selected from the elements of Groups 6 to 11 of the periodic table, L is a bridging ligand, and m is 0,-, 2-, 3- or Represents 4-. Specific examples of the ligand represented by L include:
Halides (fluoride, chloride, bromide and iodide),
Examples include cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide, and aquo ligands, nitrosyl, thionitrosyl, and the like, and preferably aquo, nitrosyl, and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

Particularly preferred examples of M are rhodium (Rh), ruthenium (Ru), rhenium (Re) and osmium (Os).

Specific examples of the transition metal coordination complex are shown below.

[0064] 1: [RhCl _6] ^3- 2: [RuCl _6] ^3- 3: [ReCl _6] ^3- 4: [RuBr _6] ^3- 5: [OsCl _6] ^3- 6: [CrCl _6] ^{4 -} 7: [Ru (NO) Cl _5] ^2- 8: [RuBr ₄ (H ₂ O)] ^2- 9: _{[Ru (NO) (H 2 O} ) Cl 4 ] ^- 10: [RhCl ₅ (H ₂ O)] ^2- 11: [Re (NO) Cl _5] ^2- 12: [Re (NO) CN _5] ^2- 13: [Re (NO) ClCN _4] ^2- 14: [Rh (NO) ₂ Cl _4] ^- 15: _{[Rh (NO) (H 2 O} ) Cl 4 ] ^- 16: [Ru (NO) CN _5] ^2- 17: [Fe (CN) _6] ^3- 18: [Rh (NS) Cl _5] ^2- 19: [Os (NO) Cl _5] ^2- 20: [Cr (NO) Cl _5] ^2- 21: [Re (NO) Cl _5] ^- 22: [Os (NS) Cl ₄ (TeCN )] ^2- 23: Ru (NS) Cl _5] ^2- 24: _{[Re (NS) Cl 4 (SeCN} ) ] ^2- 25: [Os (NS) Cl (SCN) 4 ] ^2- 26: [Ir (NO) Cl _5] ^{2 -} may be an ion or complex ion is one kind of these metals, the metal of the same kind of metal or different may be used alone or in combination. The content of these metal ions or complex ions is generally 1 × 10 ⁻⁹ to 1 mol per mol of silver halide.
1 × 10 ⁻² mol is appropriate, and preferably 1 × 10 ⁻⁸ to
It is 1 × 10 ^-4 mol. These compounds providing a metal ion or a complex ion are preferably added during silver halide grain formation and incorporated into silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, It may be added at any stage before and after the chemical sensitization, but it is particularly preferable to add at the stage of nucleation, growth, and physical ripening, more preferably, at the stage of nucleation and growth, most preferably. It is added at the stage of nucleation.

In the addition, the compound may be added in several divided portions, may be added uniformly in the silver halide grains, or may be added to silver halide grains.
-306236, 3-167545, 4-76
No. 534, No. 6-110146, No. 5-273683
As described in Japanese Patent Application Laid-Open No. H10-284, etc., the particles can be contained in the particles with a distribution. Preferably, a distribution can be provided inside the particles.

These metal compounds can be added by dissolving them in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). For example, a method in which an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a silver salt solution. A method in which silver halide grains are prepared by a method of simultaneous mixing of three liquids when a halide solution is simultaneously mixed as a third aqueous solution, and a method in which a required amount of an aqueous solution of a metal compound is charged into a reaction vessel during grain formation. Alternatively, there is a method in which another silver halide grain doped with a metal ion or a complex ion in advance during the preparation of silver halide is added and dissolved. In particular, a method of adding an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble halide solution. When adding to the surface of the particles, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during or at the end of physical ripening, or at the time of chemical ripening.

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

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

The compounds preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method include known compounds,
For example, compounds described in JP-A-7-128768 can be used.

Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, and P = Te bond Compounds having the formula: tellurocarboxylates, Te-organyltellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, Te-containing heterocycles, tellurocarbonyl compounds, An inorganic tellurium compound, a colloidal tellurium compound, or the like can be used.

Compounds preferably used in the noble metal sensitization method include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide or US Pat. No. 2,448,060, British Patent 618, No. 061 or the like can be preferably used.

Specific compounds preferably used in the reduction sensitization method include, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfonic acid, hydrazine derivatives, borane compounds, silane compounds,
A polyamine compound or the like can be used.

The pH of the emulsion was 7 or more, and the pAg was 8.
Reduction sensitization can be achieved by ripening while keeping at 3 or less. Further, reduction sensitization can be achieved by introducing a single addition portion of silver ions during grain formation.

The heat-developable photographic light-sensitive material of the present invention comprises cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes as spectral sensitizing dyes. Etc. can be used. For example, JP-A-63-1598
No. 41, No. 60-140335, No. 63-23143
No. 7, 63-259,651 and 63-304242
No. 63-15245, U.S. Pat. No. 4,639,4
No. 14, No. 4,740,455, No. 4,741,
No. 966, No. 4,751,175, No. 4,83
The spectral sensitizing dyes described in 5,096 can be used.

Useful spectral sensitizing dyes for use in the present invention include, for example, Research Disclosure.
(Hereinafter abbreviated as RD) Section 17643 IV-A (p.23, December 1978) and Item 1831X (1978)
August, p. 437) or in the literature cited. In particular, a spectral sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers and scanners can be advantageously selected. For example, JP-A-9
-34078, 9-54409, 9-8067
The compound described in No. 9 is preferably used.

Useful cyanine dyes are, for example, cyanine dyes having a basic nucleus such as a thiazoline nucleus, an oxazoline nucleus, a pyrroline nucleus, a pyridine nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus and an imidazole nucleus. Preferred useful merocyanine dyes include:
In addition to the above basic nuclei, acidic nuclei such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus are also included.

These spectral sensitizing dyes may be used alone or in combination, and the combination of spectral sensitizing dyes is often used particularly for supersensitization.

In addition to the spectral 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 spectral sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in RD 176 Vol.
43 (issued in December 1978), page 23, IV, J, or Japanese Patent Publication No. 9-25500, Japanese Patent Publication No. 43-4933.
JP-A-59-19032 and JP-A-59-192242.
No. etc.

In the photothermographic material of the present invention, when a hydrazine derivative is contained as a high contrast agent, the effect is regrettedly exhibited.

As the hydrazine derivative, a compound represented by the following general formula [H] is preferable.

[0082]

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In the formula, A ₀ represents an aliphatic group, an aromatic group, a heterocyclic group or a -G ₀ -D ₀ group which may have a substituent;
B ₀ represents a blocking group, and A ₁ and A ₂ each represent a hydrogen atom, or one represents a hydrogen atom and the other represents an acyl group, a sulfonyl group, or an oxalyl group. Here, G ₀ is -CO-
Group, -COCO- group, -CS- group, -C (= NG ₁ D ₁ )
— Group, —SO— group, —SO ₂ — group or —P (O) (G ₁ D
₁ ) represents a group, G ₁ represents a mere bond, an —O— group, —S—
Group or -N (D ₁₎ - represents a group, D ₁ is an aliphatic group, an aromatic group, a heterocyclic group or a hydrogen atom, a plurality of D ₁ in the molecule
If they are present, they can be the same or different. D ₀ is a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group,
Represents an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group.

In the general formula [H], the aliphatic group represented by A ₀ preferably has 1 to 30 carbon atoms, and particularly preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. For example, methyl group, ethyl group, t-butyl group, octyl group, cyclohexyl group, benzyl group,
These may be further substituted with a suitable substituent (for example, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, sulfoxy group, sulfonamide group, sulfamoyl group, acylamino group, ureido group, etc.).

In the general formula [H], the aromatic group represented by A ₀ is preferably a monocyclic or condensed-ring aryl group, for example, a benzene ring or a naphthalene ring, and a heterocyclic group represented by A _0. The group is preferably a heterocyclic ring containing at least one heteroatom selected from nitrogen, sulfur, and oxygen atom in a single ring or a condensed ring, for example, a pyrrolidine ring, an imidazole ring, a tetrahydrofuran ring, a morpholine ring, a pyridine ring, a pyrimidine ring, a quinoline ring, a thiazole ring, a benzothiazole ring, a thiophene ring, a furan ring, and, in -G ₀ -D ₀ group represented by A _0, G ₀ is -CO
Group, -COCO- group, -CS- group, -C (= NG
₁ D ₁₎ - group, -SO- group, -SO ₂ - group or -P (O)
(G ₁ D ₁ ) — represents a group. G ₁ is a mere bond, -O-
A group, —S— group or —N (D ₁ ) — group, wherein D ₁ represents an aliphatic group, an aromatic group, a heterocyclic group or a hydrogen atom, and when a plurality of D ₁ are present in the molecule, They can be the same or different. D ₀ is a hydrogen atom, an aliphatic group, an aromatic group,
It represents a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group, and preferable D ₀ includes a hydrogen atom, an alkyl group, an alkoxy group, an amino group, and the like. Aromatic groups A _0, heterocyclic group or -G ₀ -D ₀ group may have a substituent.

Particularly preferred as A ₀ are an aryl group and a -G ₀ -D ₀ group.

In the general formula [H], A ₀ preferably contains at least one diffusion-resistant group or a silver halide-adsorbing group. As the diffusion-resistant group, a ballast group commonly used in immobile photographic additives such as couplers is preferable, and as the ballast group, a photographically inert alkyl group, alkenyl group, alkynyl group, alkoxy group, phenyl group, Examples thereof include a phenoxy group and an alkylphenoxy group, and the total number of carbon atoms in the substituent is preferably 8 or more.

In the general formula [H], examples of the silver halide adsorption promoting group include thiourea, thiourethane group, mercapto group, thioether group, thione group, heterocyclic group, thioamide heterocyclic group, mercapto heterocyclic group, 64-9
No. 0439.

In the general formula [H], B ₀ represents a blocking group, preferably -G ₀ -D ₀ group, and G ₀ represents-
CO- group, -COCO- group, -CS- group, -C (= NG
₁ D ₁₎ - group, -SO- group, -SO ₂ - group or -P (O)
(G ₁ D ₁ ) — represents a group. Preferred G ₀ is -CO-
Group, -COCO- group, G ₁ is a mere bond,
—O—, —S— or —N (D ₁ ) —, wherein D ₁ represents an aliphatic group, an aromatic group, a heterocyclic group or a hydrogen atom, and a plurality of D ₁ are present in the molecule If so, they may be the same or different. D ₀ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group, and preferred D ₀ is a hydrogen atom, an alkyl group, an alkoxy group, And an amino group. A ₁ and A ₂ are both hydrogen atoms, or one is a hydrogen atom and the other is an acyl group (acetyl group, trifluoroacetyl group, benzoyl group, etc.), a sulfonyl group (methanesulfonyl group, toluenesulfonyl group, etc.), or an oxalyl group (Such as an ethoxalyl group).

Next, specific examples of the compound represented by the general formula [H] are shown below, but the present invention is not limited thereto.

[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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Other hydrazine derivatives that can be preferably used include compounds H-1 to H-29 described in columns 11 to 20 of US Pat. No. 5,545,505.
U.S. Pat. No. 5,464,738 column 9 to column 11
And compounds 1 to 12.

[0098] These hydrazine derivatives can be synthesized by a known method.

The hydrazine derivative-added layer is a photosensitive layer containing a silver halide emulsion and / or a layer adjacent to the photosensitive layer. The optimum amount is not uniform depending on the grain size of the silver halide grains, the halogen composition, the degree of chemical sensitization, the type of the inhibitor, and the like, but is preferably 10 ^-6 to 10 per mol of silver halide.
^The preferred range is about ^-1 mol, particularly 10 ^-5 to 10 ^-2 mol.

The photothermographic material of the present invention includes hydroxylamine compounds, alkanolamine compounds and ammonium phthalate compounds described in US Pat. No. 5,545,505, and US Pat. No. 5,545,507. Hydroxamic acid compounds of US Pat. No. 5,558,983
N-acyl-hydrazine compounds described in U.S. Pat. No. 5,545,515, acrylonitrile compounds described in U.S. Pat. No. 5,545,515, benzhydrol, diphenylphosphine, dialkylpiperidine and alkyl described in U.S. Pat. No. 5,937,449. It is preferable to add a hardening accelerator such as a hydrogen atom donor compound such as -β-ketoester. Among them, a quaternary onium compound represented by the following general formula (P) and an amino compound represented by the general formula [Na] are preferably used.

[0101]

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In the formula, Q represents a nitrogen atom or a phosphorus atom;
₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom or a substituent, and X ⁻ represents an anion. Incidentally, R _{1 to} R ₄ may be connected to each other to form a ring.

[0103]

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In the formula [Na], R ₁₁ , R ₁₂ and R ₁₃ each represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, an aryl group, a substituted aryl group, Represents an unsaturated heterocyclic ring. R ₁₁ , R ₁₂ and R ₁₃ may form a ring. Particularly preferred are aliphatic tertiary amine compounds.
These compounds preferably have a diffusion-resistant group or a silver halide adsorption group in the molecule. Molecular weight 100 or more compounds are preferred in order to have a diffusion-resistant, still more preferably a molecular weight of 300 or more, include those having the same meaning as non-diffusible group in A ₀ in the general formula (H).
Further, preferred adsorbing groups include a heterocyclic ring, a mercapto group,
Examples include a thioether group, a thione group, and a thiourea group.

As a more preferable contrast enhancement accelerator than the contrast enhancement accelerator represented by the general formula [Na], the following general formula [Na]
2].

[0106]

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In the general formula [Na2], R ¹ , R ² , R
³ and R ⁴ are each a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group,
Represents a substituted alkynyl group, an aryl group, a substituted aryl group, or a saturated or unsaturated heterocyclic ring. These can be linked to each other to form a ring. Also, R ¹ and R ² , R ³
And R ⁴ are not simultaneously hydrogen atoms. X is S, S
represents an e or Te atom. L ¹ and L ² each represent a divalent linking group. Specific examples include the following groups or combinations thereof, and groups having an appropriate substituent (eg, an alkylene group, an alkenylene group, an arylene group, an acylamino group, a sulfonamide group, and the like).

-CH _2- , -CH = CH-, -C ₂ H
₄ -, _{pyridinediyl, -N (Z 1) - (} Z 1 represents a hydrogen atom, an alkyl group or an aryl group), - O -, - S
-, - (CO) -, - (SO 2) -, - CH 2 N-.

The linking group represented by L ¹ or L ² preferably contains at least one or more of the following structures in the linking group.

-[CH ₂ CH ₂ O]-,-[C (CH ₃ )
_{HCH 2 O] -, - [} OC (CH 3) HCH 2 O] -, -
_{[OCH 2 C (OH) HCH} 2] -.

The following are specific examples of the high contrast accelerator represented by the general formula [Na] or [Na2].

[0112]

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[0113]

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[0114]

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[0115]

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In the general formula (P), the substituent represented by R _{1 to} R ₄ is an alkyl group (methyl group, ethyl group,
Propyl group, butyl group, hexyl group, cyclohexyl group, etc., alkenyl group (allyl group, butenyl group, etc.), alkynyl group (propargyl group, butynyl group, etc.), aryl group (phenyl group, naphthyl group, etc.), heterocyclic group (Piperidinyl group, piperazinyl group, morpholinyl group, pyridyl group, furyl group, thienyl group, tetrahydrofuryl group, tetrahydrothienyl group, sulfolanyl group, etc.), amino group and the like.

The ring which may be formed by connecting R _{1 to} R ₄ to each other includes a piperidine ring, a morpholine ring, a piperazine ring,
Examples include a quinuclidine ring, a pyridine ring, a pyrrole ring, an imidazole ring, a triazole ring, and a tetrazole ring.

The groups represented by R _{1 to} R ₄ are a hydroxyl group,
It may have a substituent such as an alkoxy group, an aryloxy group, a carboxyl group, a sulfo group, an alkyl group and an aryl group.

As R ₁ , R ₂ , R ₃ and R ₄ , a hydrogen atom and an alkyl group are preferred.

Examples of the anion represented by X ⁻ include inorganic and organic anions such as a halogen ion, a sulfate ion, a nitrate ion, an acetate ion and a p-toluenesulfonic acid ion.

More preferably, the following general formulas (Pa) and (P
b) or a compound represented by (Pc); and a compound represented by the following general formula [T].

[0122]

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In the formula, A ¹ , A ² , A ³ , A ⁴ and A ⁵ represent a group of nonmetallic atoms for completing a nitrogen-containing heterocyclic ring, and may contain an oxygen atom, a nitrogen atom and a sulfur atom. And the benzene ring may be condensed. A ¹ , A ² , A ³ , A ⁴ and A ⁵
May have a substituent and may be the same or different. Examples of the substituent include an alkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, a halogen atom, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfo group, a carboxy group, a hydroxyl group, an alkoxy group, and an aryloxy group. Amide group, sulfamoyl group, carbamoyl group, ureido group, amino group, sulfonamide group, sulfonyl group, cyano group, nitro group, mercapto group, alkylthio group and arylthio group. Preferred examples of A ¹ , A ² , A ³ , A ⁴ and A ⁵ include a 5- to 6-membered ring (pyridine,
Imidazole, thiozole, oxazole, pyrazine,
Each ring such as pyrimidine), and a more preferred example is a pyridine ring.

_BP represents a divalent linking group, and m represents 0 or 1
Represents Examples of the divalent linking group include an alkylene group, an arylene group, an alkenylene group, —SO ₂ —, —SO—, and —O
—, —S—, —CO—, and —N (R ⁶ ) — (R ⁶ represents an alkyl group, an aryl group, or a hydrogen atom) alone or in combination. Preferred examples of B _p include an alkylene group and an alkenylene group.

R ¹ , R ² and R ⁵ each have 1 to 20 carbon atoms
Represents an alkyl group. R ¹ and R ² may be the same or different. The alkyl group represents a substituted or unsubstituted alkyl group, and the substituent is the same as the substituents described as the substituents for A ¹ , A ² , A ³ , A ⁴ and A ⁵ .

Preferred examples of R ¹ , R ² and R ⁵ include:
Each is an alkyl group having 4 to 10 carbon atoms. More preferred examples include a substituted or unsubstituted aryl-substituted alkyl group.

[0127] X _p ^- is a counter ion necessary to refer balancing the charge of the whole molecule, expressed as chlorine ion, bromine ion, iodine ion, nitrate ion, sulfate ion, p- toluenesulfonate, the oxalato or the like. n _p represents the number of counter ions required to balance the charge of the whole molecule, and n _p is 0 in the case of an internal salt.

[0128]

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The substituents R ₅ and R ₆ of the phenyl group of the triphenyltetrazolium compound represented by the general formula [T],
R ₇ is preferably a hydrogen atom or a compound having a negative Hammett sigma value (σP) indicating the degree of electron withdrawing property.

The Hammett's sigma value at the phenyl group is described in many literatures, for example, Journal of Medical Chemistry.
Chemistry) 20, vol. 304, p. As a group having a particularly preferable negative sigma value, for example, a methyl group (σP = −0.17 or less, and
P value), ethyl group (-0.15), cyclopropyl group (-0.21), n-propyl group (-0.13), is
o-propyl group (-0.15), cyclobutyl group (-
0.15), n-butyl group (-0.16), iso-butyl group (-0.20), n-pentyl group (-0.1
5), cyclohexyl group (-0.22), amino group (-
0.66), acetylamino group (-0.15), hydroxyl group (-0.37), methoxy group (-0.27),
Ethoxy group (-0.24), propoxy group (-0.2
5), butoxy group (-0.32), pentoxy group (-
0.34), etc., each of which has the general formula [T]
Is useful as a substituent of the compound of

N represents 1 or 2, and examples of the anion represented by X _T ^n- include halogen ions such as chloride ion, bromide ion and iodide ion, nitric acid, sulfuric acid, and the like.
Acid radicals of inorganic acids such as perchloric acid, acid radicals of organic acids such as sulfonic acid and carboxylic acid, anionic activators, specifically p-
Lower alkylbenzene sulfonic acid anions such as toluene sulfonic acid anion; higher alkyl benzene sulfonic acid anions such as p-dodecyl benzene sulfonic acid anion; higher alkyl sulfate anions such as lauryl sulfate anion; boric acid anions such as tetraphenyl boron; Dialkyl sulfosuccinate anions such as 2-ethylhexyl sulfosuccinate anion,
Examples thereof include higher fatty acid anions such as cetyl polyethenoxy sulfate anion, and polymers having an acid radical attached to a polymer such as polyacrylate anion.

Hereinafter, specific examples of the quaternary onium compound will be shown below, but it should not be construed that the invention is limited thereto.

[0133]

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[0134]

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[0135]

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[0136]

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[0137]

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[0138]

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[0139]

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[0140]

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[0141]

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[0142]

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The above quaternary onium compound can be easily synthesized according to a known method. For example, the above tetrazolium compound can be obtained from Chemical Reviews 55 p. Three
35-483 can be referred to.

The addition amount of these quaternary onium compounds is about 1 × 10 ^-8 to 1 mol, preferably 1 × 10 ^-7 to 1 × 10 ^-1 mol per mol of silver halide. These can be added to the light-sensitive material at any time from the time of silver halide grain formation to the time of coating.

A quaternary onium compound and an amino compound are
They may be used alone or in combination of two or more.
The compound may be added to any of the constituent layers of the photosensitive material, but is preferably added to at least one of the constituent layers on the side having the photosensitive layer, further to the photosensitive layer and / or an adjacent layer thereof.

The photothermographic material of the present invention contains a reducing agent. Examples of suitable reducing agents are described in US Pat.
448, 3,773,512, 3,593,8
No. 63 and Research Disclosure
Nos. 17029 and 29996, and include the following. Aminohydroxycycloalkenonone compounds (eg, 2-hydroxypiperidino-2-cyclohexenone); aminoreductones esters (eg, piperidinohexose reductone monoacetate) as precursors of reducing agents; N- Hydroxyurea derivatives (for example, Np-methylphenyl-N
Hydrazones of aldehydes or ketones (e.g. anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (e.g.
Hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (eg, benzenesulfhydroxamic acid); sulfonamidoanilines (eg, 4- (N- Methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone); tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydro) Aminooxins; Azines (eg, a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid); a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine; Hydroxanoic acids Combinations of azines and sulfonamidophenols; α-cyanophenylacetic acid derivatives; combinations of bis-β-naphthol and 1,3-dihydroxybenzene derivatives; 5-pyrazolones; sulfonamidophenol reducing agents; 2-phenylindane-1 ,
3-dione and the like; chroman; 1,4-dihydropyridines (eg, 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine); bisphenols (eg, bis (2-hydroxy-3- t-butyl-5
-Methylphenyl) methane, bis (6-hydroxy-m
-Tri) mesitol, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
4,5-ethylidene-bis (2-t-butyl-6-methyl) phenol), ultraviolet-sensitive ascorbic acid derivatives and 3-pyrazolidones. Among them, particularly preferred reducing agents are hindered phenols. Examples of the hindered phenols include compounds represented by the following general formula (A).

[0147]

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In the formula, R represents a hydrogen atom or a group having 1 to 1 carbon atoms.
10 alkyl group (e.g., -C ₄ H _9, 2,4,4-trimethyl pentyl) represents, R 'and R "is an alkyl group having 1 to 5 carbon atoms (e.g., methyl, ethyl, t- butyl ).

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

[0150]

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[0151]

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The amount of the reducing agent including the compound represented by formula (A) is preferably 1 × 1 per mol of silver.
It is from 0 ^-2 to 10 mol, especially from 1 x 10 ^{-2 to} 1.5 mol.

In the photothermographic material of the present invention, it is desirable to use an additive (hereinafter referred to as a color tone agent) called a color tone agent, a color tone imparting agent or an activator toner.
The color tone agent participates in the redox reaction between the organic silver salt and the reducing agent,
It has the function of making the resulting silver image dark, especially black.

Examples of suitable toning agents used in the present invention are R
D-17029, which includes the following:

Imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (for example, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2 , 4-thiazolidinedione); naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt); mercaptans (eg, 3
-Mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (for example,
N- (dimethylaminomethyl) phthalimide); blocked pyrazoles, isothiuronium (isoth
uronium) derivatives and certain photobleaches (eg, N, N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8-
A combination of (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole; a merocyanine dye (e.g., 3-ethyl-5-((3-ethyl -2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene) -2-thio-2,4
Oxazolidinedione); phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (for example, 4-
(1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3
-Dihydro-1,4-phthalazinedione); a combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); phthalazine + phthalate Acid combinations; phthalazine (including phthalazine adducts) and maleic anhydride,
And phthalic acid, 2,3-naphthalenedicarboxylic acid or o
At least one selected from phenylene acid derivatives and anhydrides thereof (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride);
Quinazolinediones, benzoxazines, naloxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetric triazines (E.g., 2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (e.g., 3,
6-dimercapto-1,4-diphenyl-1H, 4H-
2,3a, 5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

In the photothermographic material of the present invention, various surfactants are used as a coating aid. Among them, a fluorine-based surfactant is preferably used for improving charging characteristics and preventing spot-like coating failure.

In the heat-developable material of the present invention, a mercapto compound, a disulfide compound, a thione compound and a thione compound are used for suppressing or accelerating the development to control the development, for improving the spectral sensitization efficiency and for improving the storage stability before and after the development. Compounds can be included. Further, the photothermographic material of the present invention may contain an antifoggant.

Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other forming layers. The photothermographic material of the invention may contain, for example, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid, and the like. These additives and the other additives mentioned above are RD Item
17029 (pp. 9-15, June 1978) can be preferably used.

The photosensitive layer may be composed of a plurality of layers, and the sensitivity may be changed to a high-sensitivity layer / low-sensitivity layer or a low-sensitivity layer / high-sensitivity layer for adjusting the gradation. Further, in order to control the amount or wavelength distribution of light passing through the photosensitive layer, a filter dye layer may be formed on the same side as the photosensitive layer and / or an antihalation dye layer, a so-called backing layer, may be formed on the opposite side. The photosensitive layer may contain a dye or a pigment. These non-photosensitive layers may contain a slip agent such as a polysiloxane compound, wax, or liquid paraffin in addition to the binder and the matting agent.

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

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

Further, a heat-treated plastic support may be used. The plastics to be employed include the above-mentioned plastics. The heat treatment of the support means that after forming these supports and before the photosensitive layer is applied,
The support may be heated at a temperature 30 ° C. or higher, preferably 35 ° C. or higher, more preferably 40 ° C. or higher than the glass transition point of the support.

In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer can be contained in the constituent layer in order to improve the chargeability. These may be contained in any layer, but are preferably an undercoat layer, a backing layer, a layer between the photosensitive layer and the undercoat, and the like.

The method of exposing and recording an image on the photothermographic material according to the present invention includes, for example, a method of directly photographing, a method of exposing through a film using a printer or a enlarger, and an exposing apparatus such as a copying machine. A method of scanning and exposing an original image through a slit or the like, and a method of scanning and exposing image information by emitting a light emitting diode, various lasers (laser diode, gas laser, etc.) via an electric signal (Japanese Patent Laid-Open No. 2-129625). , Japanese Patent Application No. 3-
No. 338182, No. 4-009838, No. 04-28
1442, etc.), image information is CR
T, a liquid crystal display, an electroluminescence display, a plasma display, and the like, a method of outputting to an image display device and performing exposure directly or via an optical system.

As a light source for recording an image on the photothermographic material, natural light, a tungsten lamp, a light emitting diode, a laser light source, a CRT light source, etc., as described above, US Pat. No. 4,500,626, and JP-A-2-053378. issue,
The light source and the exposure method described in JP-A-2-054672 can be used. Alternatively, image exposure can be performed using a wavelength conversion element by combining a non-linear optical material with a light source such as a laser beam.

Semiconductor laser diodes are widely used in graphic arts as photographic recording elements in image forming apparatuses. The image forming apparatus typically uses a laser diode having an output of 5 to 250 mW. The use of laser diodes follows from the well-established use of lasers (argon ions, helium neon, etc.) common in silver halide based recording elements.

Typical laser light sources include an argon ion laser, a helium neon laser, and an infrared semiconductor laser diode. These photographic elements are usually designed to produce dots that are fine enough for halftone images. Details of photographic films and papers suitable for optical drawing and scanning applications can be found in RD33355 (January 1992), No. 1
It is described in columns 1.3 and 11.4.

In the present invention, the exposure is preferably performed by laser scanning exposure, and there is no particular limitation as long as the angle between the exposed surface of the photosensitive material and the scanning laser beam is in the range of 1 to 90 °. The beam spot diameter on the exposed surface of the photosensitive material when the laser beam is scanned on the photosensitive material is preferably 300 μm or less, and is not particularly limited. The exposure in the present invention may use a laser scanning exposure machine that emits a scanning laser beam that is a vertical multi.

As a laser scanning method, there are an outer cylindrical scan, an inner cylindrical scan, and a plane scan. In outer surface cylindrical scanning, laser exposure is performed while rotating a drum around which a recording material is wound around the outer surface, and rotation of the drum is main scanning and movement of laser light is sub scanning. In the inner cylindrical scanning, a recording material is fixed on the inner surface of the drum, a laser beam is irradiated from the inside, and a main scan is performed in the circumferential direction by rotating a part or all of the optical system, and a part of the optical system or Sub-scanning is performed in the axial direction by moving the whole in a straight line parallel to the axis of the drum. In the planar scanning, the main scanning of the laser beam is performed by combining a polygon mirror or a galvanometer mirror with an fθ lens or the like, and the sub-scanning is performed by moving the recording medium.
Outer cylinder scanning and inner cylinder scanning are easier to improve the accuracy of the optical system and are more suitable for high-density recording.

In the present invention, various exposure scanning methods,
Alternatively, the emulsion layer of the heat-developable photosensitive material may be directed upward or downward depending on the transport method after exposure. It is preferable to transmit the judgment after the exposure or the result of the judgment to a mechanism for inverting the photosensitive material before or in the thermal automatic machine. In some cases, the worker may manually convey the film to the automatic thermal developing machine after the exposure.

[0171]

EXAMPLES The present invention will be described below in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Example Sample 1 as a photothermographic material was prepared according to the following method.

(Preparation of Undercoated PET Support) A commercially available biaxially stretched and heat-fixed PET film having a thickness of 100 μm is subjected to a corona discharge treatment of 8 W / m ² · min on one side, and The coating liquid a-1 was applied to a thickness of 0.8 μm and dried to form an undercoating layer A-1. 0.
It was applied so as to have a thickness of 8 μm and dried to obtain an undercoat layer B-1 having an antistatic treatment.

<< Undercoat Coating Solution a-1 >> Butyl acrylate (30% by weight) t-butyl acrylate (20% by weight) Styrene (25% by weight) 2-hydroxyethyl acrylate (25% by weight) copolymer latex liquid (Solid content 30%) 270 g (C-1) 0.6 g hexamethylene-1,6-bis (ethylene urea) 0.8 g polystyrene fine particles (average particle diameter 3 μm) 0.05 g colloidal silica (average particle diameter 90 μm) 0 Make up to 1 liter with 1g water.

<< Undercoat Coating Solution b-1 >> SnO ₂ / Sb (9/1 weight ratio, average particle size 0.18 μm) Amount to become 200 mg / m ² Butyl acrylate (30% by weight) Styrene (20% by weight) Glycidyl acrylate (40% by weight) copolymer latex liquid (solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finished to 1 liter with water.

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

<< Coating solution a-2 for lower undercoat >> Gelatin 0.4 g / m ² Weight (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 to 1 liter with water.

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

[0179]

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[0180]

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(Heat Treatment of Support) In the above-mentioned undercoat drying step of the undercoated support, the support was heated at 140 ° C.
Thereafter, it was gradually cooled.

(Preparation of silver halide emulsion A) 900 m of water
7.5 g of inert gelatin and 10 ml of potassium bromide
mg, and adjusted to a temperature of 35 ° C. and a pH of 3.0, and 370 ml of an aqueous solution containing 74 g of silver nitrate (60/3
1 mol of silver of an aqueous solution and [Ir (NO) Cl _5] salt per mole silver 1 × 10 ^-6 mol, and rhodium chloride salt comprises sodium chloride and potassium bromide and potassium iodide in a molar ratio of 8/2) 1 × 10 ^-6 mol per 1 g was added by the controlled double jet method while keeping the pAg at 7.7. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-
Add tetrazaindene, adjust pH to 8 with NaOH, pA
By adjusting the g to 6.5, reduction sensitization was performed to obtain cubic silver halide grains having an average grain size of 0.06 μm, a monodispersity of 10%, a variation coefficient of projected diameter area of 8%, and a [100] face ratio of 87%. Was. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment to prepare a silver halide emulsion A.

(Preparation of Na Behenate Solution) In 945 ml of pure water, 32.4 g of behenic acid, 9.9 g of arachidic acid and 5.6 g of stearic acid were dissolved at 90 ° C. Next, while stirring at a high speed, a 1.5 mol / L aqueous sodium hydroxide solution 9 was added.
8 ml was added. Next, after adding 0.93 ml of concentrated nitric acid, the mixture was cooled to 55 ° C. and stirred for 30 minutes to obtain a sodium behenate solution.

(Preparation of Preform Emulsion of Silver Behenate and Silver Halide Emulsion A) 15.1 g of the silver halide emulsion A was added to the above sodium behenate solution, and the pH was adjusted to 8.1 with a sodium hydroxide solution. Thereafter, 147 ml of a 1 mol / L silver nitrate solution was added over 7 minutes, the mixture was further stirred for 20 minutes, and ultrafiltration was performed to remove water-soluble salts. Next, after forming a floc of the dispersion, water was removed, washed with water six times and water was removed, and dried to prepare a preform emulsion of silver behenate and silver halide A.

(Preparation of Photosensitive Emulsion) The preform emulsion thus prepared was divided, and a solution of polyvinyl butyral (average molecular weight: 3000) in methyl ethyl ketone (17w) was prepared.
t%) 544 g and toluene 107 g were gradually added and mixed, and then a medium disperser using a 0.5 mm size ZrO ₂ bead mill at 4000 psi at 30 ° C. and 10 ° C.
Minutes of dispersion. As for silver behenate in the photosensitive emulsion obtained as described above, 90% of all silver behenate grains had a major axis of 0.5 ± 0.05 μm, a minor axis of 0.4 ± 0.05 μm,
The particles were tabular grains having a thickness of 0.01 μm and had a monodispersity of 5%.

Next, the following layers were simultaneously coated on both sides of the support by using an extrusion die coater to prepare Sample 1. The drying was performed at 60 ° C. for 15 minutes.

(Coating on Back Side) A liquid having the following composition was coated on the B-2 layer of the support.

Cellulose acetate butyrate 15 ml / m ² (10% methyl ethyl ketone solution) Dye-A 7 mg / m ² Dye-B 7 mg / m ² Matting agent: monodispersity 15% Average particle size 8 μm monodisperse silica 90 mg / m ² _{C 8 F 17 (CH 2 CH} 2 O) 12 C 8 F 17 50mg / m 2 C 9 F 17 -C 6 H 4 -SO 3 Na 10mg / m 2

[0189]

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(Coating on Photosensitive Layer Surface Side) Photosensitive layer 1: A solution having the following composition was applied on layer A-2 of the support so that the coated silver amount was 2.4 g / m ² .

Preform emulsion 240 g Sensitizing dye (0.1% methanol solution) 1.7 ml Pyridinium bromide perbromide (6% methanol solution) 3 ml Calcium bromide (0.1% methanol solution) 1.7 ml Oxidizing agent ( 10 ml methanol solution) 1.2 ml 2-4-chlorobenzoylbenzoic acid (12% methanol solution) 9.2 ml 2-mercaptobenzimidazole (1% methanol solution) 11 ml tribromomethylsulfoquinoline (5% methanol solution) 17 ml hydrazine Derivative H-26 0.4 g Hardening accelerator P-51 0.3 g Phthalazine 0.6 g 4-Methylphthalic acid 0.25 g Tetrachlorophthalic acid 0.2 g Calcium carbonate having an average particle size of 3 μm 0.1 g A-4 (20 % Methanol solution) 20.5ml Isocyanate Compound 0.5g (Mobay Corp., Desmodur N3300)

[0192]

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(Coating of Surface Protective Layer) A surface protective layer solution P-1 having the following composition was coated on the photosensitive layer 1.

The specific heat capacity of cellulose acetate butyrate, which is the main binder of the surface protective layer solution, is 1.4.
It was 6 kJ / (kg · K). In addition, the specific heat capacity of the binder was measured using the method described in JIS K 7123.

<< Surface Protective Layer Solution P-1 >> Acetone 5 ml / m ² Methyl ethyl ketone 21 ml / m ² Cellulose acetate butyrate 2.3 g / m ² Methanol 7 ml / m ² Phthalazine 250 mg / m ² Developer (20% methanol solution) 10 ml / m ² matting agent: monodispersion degree 10% average particle size 4 μm monodispersed silica 5 mg / m ² CH ₂ ＣＨCHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH = CH ₂ 35 mg / m ² fluorinated surfactant agent: in _{C 12 F 25 (CH 2 CH} 2 O) 10 C1 2 F 25 10mg / m 2 C 8 F 17 -C 6 H 4 -SO 3 Na 10mg / m sample 1 produced by ^two or more silver behenate Samples 2 to 16 were prepared in the same manner as Sample 1 except that the monodispersity, the binder of the surface protective layer solution, and the coating method were changed as shown in Tables 1 and 2. In addition, the specific change items with respect to the sample 1 in Table 1 and Table 2 are shown below.

1) Kind of silver behenate: Monodispersity of 30% and 45% prepared by adjusting the dispersion time of a media disperser in place of the silver behenate having a monodispersity of 5% used in Sample 1 was used. Silver behenate was used.

2) Change of Surface Protective Layer Solution Surface Protective Layer Solution P-2: Prepared in the same manner as Surface Protective Layer Solution P-1 except that vinyl chloride was used instead of cellulose acetate butyrate as a binder. The specific heat capacity of vinyl chloride was 1.05 kJ / (kg · K).

Surface protective layer solution P-3: Prepared in the same manner as surface protective layer solution P-1 except that ethyl cellulose was used instead of cellulose acetate butyrate as a binder. The specific heat capacity of ethyl cellulose is 2.93 k.
J / (kg · K).

Surface protective layer solution P-4: Prepared in the same manner as surface protective layer solution P-1 except that polymethyl methacrylate was used in place of cellulose acetate butyrate as a binder. The specific heat capacity of polymethyl methacrylate was 1.47 kJ / (kg · K).

3) Change of Coating Method Coating was performed using a reverse roll coater (C-2) or a wire bar coater (C-3) instead of the extrusion die coater (C-1).

[0201]

[Table 1]

[0202]

[Table 2]

The following items were evaluated for the samples 1 to 16 prepared as described above.

(Measurement of Surface Average Roughness Ra) The surface of the photosensitive material was coated with platinum-
After coating with a 3 nm palladium alloy, using a non-contact three-dimensional surface analyzer (RST / PLUS type manufactured by WYKO) with a magnification of 40 times as an objective lens, a visual field of 368 × 238 pixels in VSI mode. After performing the Tilt correction and the median filter treatment, the surface roughness Ra was measured.

The definition of Ra was based on the following JIS surface roughness (B0601). The measurement was performed five times at different locations to obtain an average value.

JIS Surface Roughness (B0601): Surface average roughness (center line average roughness) Ra Surface average roughness (center line average roughness) Ra is the length measured from a roughness curve in the direction of the center line. L portion, the center line of the extracted portion is the X axis, the direction of the vertical magnification is the Y axis,
When the roughness curve is represented by Y = f (X), the value obtained by the following equation is represented by nanometers (nm).

[0207]

(Equation 1)

(Evaluation of Image Density Fluctuation) << Exposure and Development >> Each of the samples prepared above was 25 cm
× 30cm, 12 ° C at 23 ° C and 50% RH
After the humidity control, exposure was performed through a wedge by an exposure machine using a semiconductor laser of 780 nm as an exposure source. At this time, the angle between the exposed surface of the photosensitive material and the
An image was formed as a degree.

Thereafter, the heat-development processing of the photosensitive material was performed by using a horizontal conveyance type automatic developing machine having a sheet heater and a plurality of opposed rollers and comprising a preheating section, a developing section, a reheating section and a cooling section. . The development was performed at 123 ° C. for 20 seconds, and the subsequent reheating was performed at 110 ° C. for 5 seconds. Thus, a sample (A) subjected to the reheating treatment was produced. At the same time, a sample (B) which did not pass through the reheating unit was also prepared. The above exposure and development treatments were all performed in a room conditioned at 23 ° C. and 50% RH.

<< Evaluation of Images >> The densities of the samples A and B prepared as described above were measured in the UV region (400 nm) using an optical densitometer (manufactured by X-rite), and the minimum density (Dmin) was measured. Part) and the maximum concentration part (Dmax part)
Were measured at five locations.

With respect to the obtained measured values, the Dmin portion judged that the average value was not more than 0.26, and the Dmax portion judged that the difference between the measured maximum value and the minimum value was not more than 0.35. .

The results obtained as described above are shown in Tables 1 and 2 above.

As is clear from Tables 1 and 2, in the developing method according to the present invention, which is carried out in an apparatus provided with a reheating unit after the developing unit, the organic silver contained in the photosensitive layer is monodispersed. A photothermographic material is used in which the specific heat capacity of the main binder contained in the protective layer is 1.3 to 2.1 J / (kg · K) and the surface average roughness of the protective layer is Ra = 50 to 150 nm. As a result, it was possible to provide a photothermographic material having little density fluctuation and extremely high image stability. Further, it can be seen that the effect of the photothermographic material produced by a method using an extrusion type die coater is much higher.

[0214]

According to the present invention, a photothermographic material, particularly a photothermographic material for printing, can be provided. More specifically, a photothermographic material having improved image density uniformity and excellent image stability in thermal development processing. A photosensitive material could be provided.

Claims (4)

[Claims] 1. A photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer above the photosensitive layer, has a means for reheating at a lower temperature than the developing section after thermal development. A photothermographic material, wherein the photothermographic material is processed by a photothermographic processor and the organic silver salt has a monodispersed particle size distribution. 2. A photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer above the photosensitive layer, has a means for reheating at a lower temperature than the developing section after thermal development. The specific heat capacity of the main binder processed by the heat development processor and contained in the protective layer is 1.3 to 2.1.
A photothermographic material characterized by kJ / (kg · K). 3. A photothermographic material having a photosensitive layer containing a silver halide and an organic silver salt on a support and a protective layer thereon has a means for reheating at a lower temperature than the developing section after thermal development. A photothermographic material, wherein the photothermographic material is processed by a heat development processor and has a surface roughness Ra of 50 to 150 nm. 4. The photothermographic material according to claim 1, wherein the photosensitive layer and the protective layer are applied by an extrusion die coater.