JP2005181497A - Heat developable photographic sensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photographic sensitive material having good moisture resistance, good storage stability and improved scuffing resistance. <P>SOLUTION: In the heat developable photographic sensitive material having on a support a photosensitive layer containing organic silver salt particles, silver halide grains and a reducing agent, the photosensitive layer also contains at least two or more of the compounds represented by formula (1) and an outermost layer on the photosensitive layer side is a moisture-proof layer consisting of a latex and a wax emulsion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-developable photographic light-sensitive material, and more particularly to a heat-developable photographic light-sensitive material having excellent humidity resistance and storage stability and improved scratch resistance.

  Many photosensitive materials having a photosensitive layer on a support and forming an image by exposing the image are known. Among them, as a system that can simplify environmental preservation and image forming means, there is a technique for forming an image by heat development. In recent years, in the field of photoengraving, reduction of waste processing liquid is strongly desired from the viewpoint of environmental conservation and space saving. Therefore, there is a technology relating to a photothermographic material for photoengraving that can be efficiently exposed by a laser scanner or a laser image setter and can form a clear black image having high resolution and sharpness. is necessary. In these heat-developable photographic light-sensitive materials, the use of solution-type processing chemicals can be eliminated, and a simpler heat-development processing system that does not damage the environment can be supplied to customers.

  A method of forming an image by thermal development is described in, for example, (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1).

When performing color printing, the photosensitive material for printing plate making usually uses a plurality of films separated for each color. They are printed on each plate and printed in layers. When films that are separated according to a plurality of colors are stacked, if they do not overlap completely, a phenomenon occurs in which the colors shift when printed. Therefore, in a heat-developable photographic light-sensitive material for printing plate making, it is an important issue how to suppress the dimensional change of the plate due to heat. As a method for improving the heat-resistant dimensional stability of the heat-developable photographic photosensitive material, heat treatment is carried out while being conveyed at a high temperature of 80 to 200 ° C. and a low tension of 0.04 to 6 kg / cm ² to reduce the thermal shrinkage of the support. Techniques are disclosed (for example, see Patent Documents 3 and 4).

  The photothermographic material is usually a reducible non-photosensitive silver source (for example, an organic silver salt), a catalytically active amount of a photocatalyst (for example, silver halide), and a silver reducing agent, usually dispersed in an organic binder matrix. Contained in the state. The photothermographic material is stable at normal temperature, but when it is heated to a high temperature (for example, 80 ° C. or higher) after exposure, redox between the reducible silver source (which functions as an oxidizing agent) and the reducing agent. Silver is produced through the reaction. This redox reaction is promoted by the catalytic action of the latent image generated by exposure. The silver produced by the reaction of the reducible silver salt in the exposed areas provides a black image that contrasts with the unexposed areas and forms an image.

  Such heat-developable photographic light-sensitive materials have a low moisture content in the low-humidity season in winter and the development reaction is difficult to proceed. There is a problem that the amount increases, the development reaction easily proceeds, the sensitivity increases, and the character line width increases.

As a conventional technique, there is known a technique (for example, see Patent Document 5) that uses vinylidene chloride latex for a protective layer to reduce the influence of character line width under high humidity. At the same time, it was found that the film strength at the time of development becomes weak, so that a roller mark is attached after conveyance by heat development, or when it is bad, it adheres to a roll and cannot be conveyed. Similarly, it was found that the scratch resistance deteriorates. The inventor has invented a technique (for example, see Patent Document 6) that uses latex and latex for the protective layer to reduce the influence of the character line width under high humidity. However, the humidity resistance is sufficient. However, as with the above-mentioned vinylidene chloride latex, it was found that the scratch resistance deteriorates as the film strength during development decreases.
US Pat. No. 3,152,904 US Pat. No. 3,457,075 D. Morgan, B.M. Shephery; Thermally Processed Silver Systems A; Imaging Processes and Materials: NEXT 8th Edition, Sturge, V. Walworth, A.D. Edited by Shepp, page 2, 1969 Japanese Patent Laid-Open No. 10-10676 Japanese Patent Laid-Open No. 10-10777 JP 2001-272742 A Japanese Patent Application No. 2003-67863

  An object of the present invention is to provide a heat-developable photographic light-sensitive material having good humidity resistance, storage stability and improved scratch resistance.

The above object of the present invention can be achieved by the following configuration.
(Claim 1)
In a photothermographic material having a photosensitive layer containing organic silver salt grains, silver halide grains and a reducing agent on a support, the photosensitive layer contains at least two compounds represented by the following general formula (1). A heat-developable photographic light-sensitive material containing an outermost layer on the photosensitive layer side, which is a moisture-proof layer composed of a latex and a wax emulsion.

[Wherein R ₁₁ , R ₁₂ and R ₁₃ each represent a hydrogen atom or a monovalent substituent, and X ₁₁ represents an electron-donating heterocyclic group, cycloalkyloxy group, cycloalkylthio group, cycloalkylamino group or Represents a cycloalkenyl group. ]
(Claim 2)
The compound represented by the general formula (1) is characterized in that the substituent represented by R ₁₁ is a cyano group, and the substituent represented by R ₁₂ or R ₁₃ is a hydroxyl group. The photothermographic material described in 1.
(Claim 3)
3. The photothermographic material according to claim 1, wherein at least one of the compounds represented by the general formula (1) is such that the electron attractive group represented by X ₁₁ is a heterocyclic group. .
(Claim 4)
4. The photothermographic material according to claim 1, wherein the wax emulsion is paraffinic.
(Claim 5)
The photothermographic material according to claim 1, wherein the photosensitive layer and the outermost layer are formed by solvent coating.
(Claim 6)
6. The photothermographic material according to claim 1, wherein the moisture-proof layer has a moisture permeability of 1 to 40 g / m ² · 24 hr.
(Claim 7)
7. The photothermographic material according to claim 1, wherein the support is a low heat shrinkable support.

  The support for a photothermographic material and the photothermographic material of the present invention have little variation in photographic performance under various environmental conditions, and have good storage stability and scratch resistance even at high temperatures. Excellent material.

  The present invention will be described in more detail. As a result of intensive studies on the above problems, the present inventor has paid attention to the nucleating agent used in the photosensitive layer, contains two or more kinds of nucleating agents having a specific structure, and the outermost layer contains wax and latex. It has been found that a heat-developable photographic light-sensitive material having good humidity resistance and storability of photographic performance and excellent scratch resistance can be obtained by providing a moisture-proof layer.

[Dampproof layer]
The moisture-proof layer of the present invention is disposed between the outermost layers and is composed of a latex and a wax emulsion. The ratio of latex to emulsion is preferably 100: 2 to 100: 100. More preferably, it is 100: 10-100: 50. When 100: 2 is lowered, the moisture-proof effect is not exhibited, and the humidity resistance of the photographic performance deteriorates. On the other hand, if the amount of the wax emulsion exceeds 100: 100, the film as the moisture-proof layer becomes weak and the scratch resistance is deteriorated.

The moisture permeability of the moisture-proof layer of the present invention is preferably 1 to 40 g / m ² · 24 hr. More preferably, it is 1-20 g / m < ² > * 24hr. When it is lower than 1 g / m ² · 24 hr, it is necessary to increase the wax emulsion ratio, the film as the moisture-proof layer becomes weak, and the scratch resistance is deteriorated. ^{On the other hand} , if it exceeds 40 g / m ² · 24 hr, the moisture-proof effect is not exhibited and the humidity resistance of the photographic performance deteriorates.

  The measuring method of moisture permeability can be measured according to JIS Z-208 (cup method).

1. Latex The type of latex of the present invention is not particularly limited, but synthetic resin-based or latex-based latex is preferred from the viewpoint of moisture resistance due to scratch resistance and film-forming properties.

  The latex in the present invention refers to a polymer component in which a water-insoluble hydrophobic polymer is dispersed as fine particles in water or a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion polymerized, the micelle dispersed, or the polymer molecule has a partially hydrophilic structure and the molecular chain itself is molecularly dispersed. Anything may be used. As for the latex according to the present invention, “synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing Co., Ltd. (1978))”, “application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara) , Published by Polymer Press Association (1993)), “Synthetic Latex Chemistry (written by Soichi Muroi, published by Polymer Press Association (1970))”, and the like.

  The Tg of the polymer constituting the latex is preferably -20 to 60 ° C. More preferably, it is 0-50 degreeC. When it is lower than −20 ° C., fluidity is generated in the film and scratch resistance is deteriorated. On the other hand, if it exceeds 60 ° C., the film-forming property is deteriorated, the moisture-proof effect is not exhibited, and the humidity resistance of the photographic performance is deteriorated. The Tg (glass transition temperature) of the latex was measured in Bull. Am. Phys. Soc. T. described in G. The numerical value calculated | required by calculation by the method of Fox is shown. In the case of using a mixture of a plurality of latexes, it is calculated by adding the mass ratio of the constituent latexes.

  The average particle size of the dispersed particles of latex is in the range of 1 to 50000 nm, more preferably about 5 to 1000 nm. Regarding the particle size distribution of the dispersed particles, those having a wide particle size distribution or monodispersed particle size distribution may be used.

  The latex according to the present invention may be a so-called core / shell type latex other than a normal latex having a uniform structure. In this case, it may be preferable to change the glass transition temperature and composition of the core and the shell. In addition, it is preferable to use two or more types of latex in order to achieve both film-forming properties, moisture-proof properties, and blocking properties. In this case, it is preferable to change the glass transition temperature and the composition as in the core-shell type.

  The latex of the present invention can be obtained by emulsion polymerization of monomers including the following ethylenically unsaturated monomers. As the emulsifier used at this time, commercially available anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants and the like can be used. Among these, it is preferable to use a reactive emulsifier in order to further improve moisture resistance. By using this reactive emulsifier, a soap-free emulsion can be obtained. Examples of reactive emulsifiers include styrene sulfonic acid soda, vinyl sulfonic acid soda, vinyl sulfonic acid soda, and emulsifiers having various ethylenically unsaturated groups.

(Synthetic resin latex)
As synthetic resin latex, the ethylenic unsaturated monomer shown below is manufactured as a copolymer by respectively making a monomer polymer or combining two or more. Examples of ethylenically unsaturated monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, metal propyl acrylate, butyl acrylate, butyl metal acrylate, hexyl acrylate, and methacrylic acid. Acrylic acid alkyl ester and methacrylic acid alkyl ester exemplified by hexyl, heptyl acrylate, heptyl methacrylate, octyl acrylate, octyl methacrylate, octadecyl acrylate, octadecyl methacrylate, and the like; 1, 2 butane, 1, 3 butane Aliphatic conjugated diene monomers such as styrene, isoprene and chloroprene; ethylenically unsaturated aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene 2,4-dibromostyrene; Unsaturated nitriles such as rilonitrile and methacrylonitrile; acrylic acid, methacrylic acid, crotonic acid, maleic acid and its anhydride, fumaric acid, itaconic acid and unsaturated dicarboxylic acid monoalkyl esters such as monomethyl maleate, monoethyl fumarate Ethylenically unsaturated carboxylic acids such as mono-normal butyl itaconate; vinyl esters such as vinyl acetate and vinyl propionate; vinylidene halides such as vinylidene chloride and vinylidene bromide; acrylic acid-2-hydroxyethyleryl, acrylic acid Hydroxyalkyl esters of ethylenically unsaturated carboxylic acids such as 2-hydroxypropyl and 2-hydroxyethyl methacrylate; glycidyl esters of ethylenically unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate Steal and monomers capable of radical polymerization such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-butoxymethyl acrylamide, diacetone acrylamide and the like can be mentioned.

  Regarding the film-forming property of the latex, it is better to increase the Tg of the polymer by containing a monomer such as methyl acrylate or methyl methacrylate having a Tg of 0 ° C. or higher. It is more preferable to contain.

(Synthetic rubber latex)
Examples of synthetic rubbers include styrene-butadiene-latex (SBR), methyl methacrylate-butadiene latex (MBR), acrylonitrile-butadiene latex (NBR), vinylpyridine-butadiene latex, and isoprene latex (IR). Styrene-diene latex is preferable because it has good water resistance, good elongation, and is less likely to cause cracks in the coating layer due to cracking. As the conjugated diene monomer, for example, 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, 2-methyl-1,3-butadiene and the like are usually used for the production of conventional latex. Things can be mentioned. These conjugated diene monomers are used alone or in combination of two or more. In the present invention, 1,3-butadiene is particularly preferably used.

  Such a conjugated diene monomer is used for imparting appropriate elasticity and film hardness to the resulting copolymer. The amount of the conjugated diene monomer used in the styrene-diene system is 10 to 80% by mass, preferably 30 to 60% by mass. If it is lower than 10%, the film-forming property is deteriorated, the moisture-proof effect is not exhibited, and the humidity resistance of the photographic performance is deteriorated. On the other hand, if it exceeds 80%, fluidity is generated in the film and the scratch resistance is deteriorated.

  Moreover, it is preferable to adjust the film forming property and the like by appropriately containing the above synthetic resin monomer in the styrene-diene latex.

2. Wax emulsion The wax emulsion used in the present invention is obtained by emulsifying wax. Examples of the wax include paraffin wax, candelilla wax, carnauba wax, rice wax, montan wax, ceresin wax, microcrystalline wax, petrolactam, Fischer-Tripush wax, polyethylene wax, montan wax and derivatives thereof, and microcrystalline wax. And derivatives thereof, hardened castor oil, liquid paraffin, stearamide, and the like, and paraffin wax is particularly preferably used. The wax emulsion may be prepared by a known method. For example, a wax, a resin, a fluidizing agent and the like may be melted by mixing and heating, and an emulsifier may be added thereto to emulsify. Examples of the resin include rosin, a rosin ester compound, and a petroleum resin. Examples of the fluidizing agent include polyhydric alcohols and esterified products of polyhydric alcohols. After these mixtures are melted, for example, surfactants such as anions, cations, and nonions, or basic compounds such as ammonia, sodium hydroxide, and potassium hydroxide, organic amines, and styrene-maleic acid copolymers are added. It can be made into a wax emulsion by emulsifying.

  Wax emulsions may be used alone or in combination of two or more. The melting point of the wax emulsion by differential scanning calorimetry (DSC) is preferably 40 to 100 ° C, more preferably 50 to 80 ° C. Here, if the melting point is less than 40 ° C., the blocking property is deteriorated, which is not preferable. Further, at a temperature higher than 100 ° C., since the wax does not sufficiently soften and flow when the coating film is dried when the moisture-proof layer is provided, the moisture resistance is deteriorated as a result of impairing the moisture-proof property.

3. Crosslinking agent A crosslinking agent may be used in the moisture-proof layer of the present invention. By using the crosslinking agent in combination with the latex and the wax emulsion, the moisture resistance is improved and the humidity resistance is improved. The crosslinking agent used in the present invention may be any of various crosslinking agents conventionally used for photographic materials such as aldehydes, epoxies, ethyleneimines, vinyl sulfones described in JP-A-50-96216. , Sulfonic acid ester-based, acryloyl-based, and carbodiimide-based cross-linking agents can be used, but in the present invention, an epoxy compound and its acid anhydride, or a silane compound are preferable.

4). Matting Agent A matting agent may be used in the moisture-proof layer of the present invention. By using the matting agent in combination with the latex and the wax emulsion, the blocking property is improved.

  The fine particles added as the matting agent in the present invention are generally fine particles of an organic or inorganic compound that is insoluble in water, and any type can be used. For example, U.S. Pat. Nos. 1,939,213, 2,701,245, 2,322,037, 3,262,6782, 3,539,344, and 3, 767, 448, etc., the organic matting agents described in the respective specifications, Nos. 1,260,772, Nos. 2,192,241, Nos. 3,257,206, Nos. 3,370, Those well known in the art such as the inorganic matting agent described in each specification such as No. 951, No. 3,523,022, No. 3,769,020 can be used. Specific examples of organic fine particles that can be used include water-dispersible vinyl polymers such as polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, polystyrene, styrene- Divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate, polytetrafluoroethylene, etc. Examples of cellulose derivatives include methylcellulose, cellulose acetate, cellulose acetate propionate, etc. Examples of starch derivatives include carboxy starch, carboxynitrophenyl starch, urea -Preferably use is made of gelatin hardened with a known hardener such as formaldehyde-starch reactant and hard gelatin made into microcapsule hollow particles by coacervate hardening It can be. As examples of the inorganic fine particles, silicon dioxide, titanium dioxide, magnesium dioxide, aluminum oxide, barium sulfate, calcium carbonate, silver chloride desensitized by a known method, silver bromide, glass, diatomaceous earth, and the like can be preferably used. .

  The above matting agents can be used by mixing different kinds of substances as required. The size and shape of the matting agent are not particularly limited, and those having an arbitrary particle size can be used. In the practice of the present invention, it is preferable to use one having a particle size of 0.1 μm to 30 μm. 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 and surface gloss of the heat-developable photographic photosensitive material, the particle size, shape, and particle size distribution are brought into a state as required when the matting agent is prepared or by mixing a plurality of matting agents. It is preferable to do.

[Solvent application]
The photosensitive layer and the outermost layer of the present invention are preferably formed by solvent coating. If these are installed by water-based coating, the moisture resistance of the vinylidene chloride layer is deteriorated, which is not preferable. A general method can be used as a solvent coating method.

[Photosensitive layer]
1. Organic silver The organic silver salt contained in the photosensitive layer of the photothermographic material of the present invention is a reducible silver source, and silver salts of organic acids and heteroorganic acids containing a reducible silver ion source, particularly Long chain (10-30, preferably 5-25 carbon atoms) aliphatic carboxylic acids and nitrogen-containing heterocyclic carboxylic acids are preferred. Also useful are organic or inorganic silver salt complexes in which the ligand has a total stability constant for silver ions of 4.0-10.0. Examples of suitable silver salts are described in Research Disclosure (RD) Nos. 17029 and 29963 and include the following: salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid) Acid, lauric acid salts); silver carboxyalkylthiourea salts (eg, 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, etc.); aldehyde and hydroxy Silver complexes of polymer reaction products with substituted aromatic carboxylic acids (eg aldehydes such as formaldehyde, acetaldehyde, butyraldehyde and salicylic acid, benzylic acid 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc. Hydroxy-substituted acids); silver salts or complexes of thiones (e.g. 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione and 3-carboxymethyl-4-methyl-4-thiazoline-2-thione); imidazole, pyrazole, urazole, 1, 2, 4- Nitric acid and silver complex or salt selected from thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole; silver salts such as saccharin and 5-chlorosalicylaldoxime A silver salt of mercaptides; Preferred silver sources are silver behenate, silver arachidate or silver stearate.

  The organic silver salt can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, as described in the normal mixing method, the reverse mixing method, the simultaneous mixing method, and Japanese Patent Application Laid-Open No. 9-127643. A controlled double jet method or the like is preferably used. For example, an alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate), and then a controlled double jet. By adding the soap and silver nitrate, an organic silver salt crystal is prepared. At that time, silver halide grains may be mixed.

2. Silver halide The silver halide grains contained in the photosensitive layer of the photothermographic material of the invention function as an optical sensor. In the present invention, in order to keep the cloudiness after image formation low and to obtain good image quality, it is preferable that the average particle size is small, the average particle size is preferably 0.03 μm or less, more preferably 0.01 to The range is 0.03 μm. Incidentally, the silver halide grains of the photothermographic material of the present invention are produced at the same time as the preparation of the organic silver salt, or mixed with the silver halide grains at the time of preparing the organic silver salt to prepare an organic It is preferable to form silver halide grains in a fused state with a silver salt to form so-called in situ silver of fine grains. In addition, the measuring method of the average grain diameter of the above-mentioned silver halide grains was taken at 50000 times with an electron microscope, the long side and the short side of each silver halide grain were measured, 100 grains were measured, and the average This is defined as the average particle size.

  Here, the grain size means the length of the edge of the silver halide grain when the silver halide grain is a so-called normal crystal of a cube or octahedron. In the case of non-normal crystals, for example, in the case of spherical, rod-like, or tabular grains, it means the diameter when considering a sphere equivalent to the volume of silver halide grains. The silver halide grains are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 0.1 to 20%.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100
In the present invention, the silver halide grains are more preferably monodisperse grains having an average grain diameter of 0.01 to 0.03 [mu] m, and the graininess of the image is also improved by using this range.

  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, further 70% or more, particularly 80% or more. Is preferred. The ratio of the Miller index [100] plane is calculated by using the adsorption dependency between the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani; Imaging Sci. 29, 165 (1985).

  Another preferred silver halide grain shape is a tabular grain. The tabular grains referred to herein are those having an aspect ratio = r / h of 3 or more when the square root of the projected area is the grain size r μm and the vertical thickness is h μm. Among them, the aspect ratio is preferably 3 or more and 50 or less. The particle size is preferably 0.03 μm or less, more preferably 0.01 to 0.03 μm. These production methods are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958, etc., and the desired tabular grains can be easily obtained. Can do. When these tabular grains are used in the present invention, the sharpness of the image is further improved.

  The composition of the silver halide grains is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. The photographic emulsion used in the present invention is P.I. Chifie et Physique Photographic (published by Paul Montel, 1967) by Glafkides. F. Duffin's Photographic Emission Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared using a method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al.

  The silver halide grains used in the present invention preferably contain ions or complex ions of metals belonging to Groups 6 to 10 of the Periodic Table of Elements in order to improve the illuminance failure and to adjust the improvements. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable.

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

  The silver halide grains in the present invention are preferably chemically sensitized. Preferred chemical sensitization methods include sulfur sensitization method, selenium sensitization method, tellurium sensitization method, noble metal sensitization method such as gold compound, platinum, palladium, iridium compound and reduction as well known in the art. A sensitization method can be used.

In the present invention, in order to prevent devitrification of the heat-developable photographic light-sensitive material, the total amount of silver halide grains and organic silver salt is 0.3 to 2.2 g per 1 m ² in terms of silver amount. 5-1.5 g is more preferable. By setting this range, a high-contrast image can be obtained. The amount of silver halide based on the total amount of silver is 50% or less, preferably 25% or less, and more preferably 0.1 to 15% by mass ratio.

  The silver halide grains in the present invention have a maximum light absorption at 350 to 450 μm, and may not particularly contain a sensitizing dye, but may be contained if necessary.

3. Reducing agents Examples of suitable reducing agents contained in the photosensitive layer of the photothermographic material of the present invention are U.S. Pat. Nos. 3,770,448, 3,773,512, and 3,593. 863, RD, and RD Nos. 17029 and 29963, and the following can be mentioned.

  Aminohydroxycycloalkenone compounds (e.g. 2-hydroxy-3-piperidino-2-cyclohexenone); aminoreductones esters (e.g. piperidinohexose reductone monoacetate) as precursors of reducing agents; N- Hydroxyurea derivatives (eg, Np-methylphenyl-N-hydroxyurea); aldehyde or ketone hydrazones (eg, anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (E.g., hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (e.g., benzenesulfuroxy). Mucinic acid); sulfonamidoanilines (eg, 4- (N-methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone) Tetrahydroquinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline); amide oximes; azines; combinations of aliphatic carboxylic acid arylhydrazides and ascorbic acid; combinations of polyhydroxybenzene and hydroxylamine; 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; Nord reducing agent; 2-phenylindane-1,3-dione, etc .; Chroman; 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine); Bisphenols (For example, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy-3-methyl Phenyl) propane, 4,4-ethylidene-bis (2-tert-butyl-6-methylphenol)), UV-sensitive ascorbic acid derivatives; hindered phenols; 3-pyrazolidones. Of these, particularly preferred reducing agents are hindered phenols.

The amount of reducing agent used is preferably 1 × 10 ⁻² to 10 mol, in particular 1 × 10 ^{−2 to} 1.5 mol, per mol of silver.

4). Nucleating agent (high contrast agent)
The photothermographic material of the present invention contains at least two compounds represented by the general formula (1). By incorporating two or more compounds according to the present invention, a photothermographic material having good humidity resistance and storage stability can be obtained. Furthermore, it discovered that the above-mentioned effect was further improved by combining with the said moisture-proof layer.

  The compound represented by the general formula (1) will be described in detail below. First, the electron donating group and the electron withdrawing group in the present invention will be described. In the present invention, the electron donating group is a substituent having a negative Hammett substituent constant σp. Examples of the electron donating group include a hydroxyl group (or a salt thereof), an alkoxy group, An aryloxy group, a heterocyclic oxy group, an amino group, an alkylamino group, an arylamino group, a heterocyclic amino group, a heterocyclic group in which σp takes a negative value, or a phenyl group substituted with these electron donating groups, etc. Can be mentioned. The electron-withdrawing group in the present invention is a substituent having a positive Hammett substituent constant σp. Examples of the electron-withdrawing group include a halogen atom, a cyano group, a nitro group, and an alkenyl group. Alkynyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, carbamoyl group, carbonamido group, sulfamoyl group, sulfonamido group, trifluoromethyl group, trichloromethyl group, phosphoryl group, Examples thereof include a carboxy group (or a salt thereof), a sulfo group (or a salt thereof), an imino group, a heterocyclic group in which σp has a positive value, or a phenyl group substituted with these electron-withdrawing groups. Hammett's law was introduced in 1935 by L. L. to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives. P. A rule of thumb proposed by Hammett, which is widely accepted today. Substituent constants obtained by Hammett's rule include a σp value and a σm value, and these values are described in many general books, “Lange's Handbook of Chemistry” (JA Dean). ) "12th sale, 1979 (Mc Graw-Hill) and" Chemical domain special issue ", No. 122, 96-103, 1979 (Nankodo), Chemical Reviews, Vol. 91, 165-195 Page, 1991. The electron-withdrawing group and the electron-donating group in the present invention are defined by the σp value, but are not limited to substituents having known values described in the above-mentioned books.

The compound represented by the general formula (1) will be described. In the formula, X ₁₁ represents an electron-donating heterocyclic group, a cycloalkyloxy group, a cycloalkylthio group, a cycloalkylamino group, or a cycloalkenyl group. As typical examples of the electron-donating heterocycle, σp described in pages 66 to 339 of “Substituent Constants for Correlation Analysis in Chemistry and Biology” (Corwin Hansch and Albert Leo) is negative, and σp is negative. Specific examples of the ring include piperidinyl group, pyrrolidinyl group, morpholino group, piperazinyl group, 3-thienyl group, 2-furyl group, 3-furyl group and 2-pyrrolo group. A 3-thienyl group, a 2-furyl group or a 3-furyl group is preferred. These heterocycles may have an arbitrary substituent as long as σp is 0 or not positive.

  Specific examples of the cycloalkyloxy group, cycloalkylthio group or cycloalkylamino group include a cyclopropyloxy group, a cyclopentyloxy group, a cyclohexyloxy group, a cycloheptyloxy group, a cyclopropylthio group, a cyclopentylthio group, Examples include cyclohexylthio group, cycloheptylthio group, cyclopropylmethylamino group, cyclopentylmethylamino group, cyclohexylmethylamino group, cycloheptylmethylamino group, and the like. A cyclopentyloxy group, a cyclohexyloxy group, a cyclopentylthio group and a cyclohexylthio group are preferred. Specific examples of the cycloalkenyl group include a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. A cyclopentenyl group or a cyclohexenyl group is preferable.

R ₁₁ , R ₁₂ and R ₁₃ each represent a hydrogen atom or a monovalent substituent. Examples of the monovalent substituent include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a heterocyclic group containing a quaternized nitrogen atom (for example, a pyridinium group), a hydroxy group, and an alkoxy group (for example, Including a group repeatedly containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, urethane group, carboxyl group, imide group, amino group, Carboxamide group, sulfonamide group, ureido group, thioureido group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, quaternary ammonio group, (alkyl, aryl, or heterocyclic) thio group, mercapto group , (Alkyl or aryl) sulfur Nyl group, (alkyl or aryl) sulfinyl group, sulfo group, sulfamoyl group, acylsulfamoyl group, (alkyl or aryl) sulfonylureido group, (alkyl or aryl) sulfonylcarbamoyl group, halogen atom, cyano group, nitro group, Examples thereof include a phosphoric acid amide group.

R ₁₁ is preferably an electron withdrawing group, more preferably a cyano group. R ₁₂ is preferably a hydrogen atom and R ₁₃ is preferably an electron donating group. Most preferably, R ₁₁ is a cyano group, R ₁₂ is a hydrogen atom, and R ₁₃ is a hydroxyl group.

  Hereinafter, although the specific example of a compound represented by General formula (1) is given, this invention is not limited to these. In addition, in the compounds listed below, when keto-enol tautomers or cis-trans geometric isomers are present, both are meant.

5). Others The binder used in the photosensitive layer and the non-photosensitive layer of the photothermographic material of the present invention is either a hydrophilic binder (a binder or latex that dissolves in water) or a hydrophobic binder (a binder that dissolves in an organic solvent). However, the binder of each layer is preferably a binder that dissolves in the same solvent system. For example, the binder of each layer of the photosensitive layer, the intermediate layer, and the protective layer are all organic solvent-based binders or hydrophilic. It is preferable that the binder be a functional binder.

  The binder used in each layer is transparent or translucent and generally colorless, and natural polymers, synthetic monopolymers and copolymers, and other media that form films are used. Specific examples of the binder include: water-soluble binders such as gelatin, gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, casein, starch, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), 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) (Eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), Poly (vinyl vinyl Tate), cellulose esters, poly (amide) and other hydrophobic binders, preferably polyvinyl butyral, cellulose acetate, cellulose acetate butyrate, polyester, polycarbonate, polyacrylic acid, polyurethane and other hydrophobic binders, particularly polyvinyl butyral, Examples thereof include hydrophobic binders such as cellulose acetate, cellulose acetate butyrate and polyester, and latex obtained by polymerizing monomers of those binder resins in water by an emulsion polymerization method or a suspension polymerization method.

  As the main solvent for dissolving the hydrophobic binder, for example, alcohols (methanol, ethanol, propanol), ketones (acetone, methyl ethyl ketone) dimethylformamide, dimethyl sulfoxide, methyl cellosolve and the like are preferably used.

  The Tg of the binder of the photosensitive layer is preferably 40 ° C. or higher. Preferably it is 40-120 degreeC, More preferably, it is 40-100 degreeC, Most preferably, it is 40-80 degreeC. When the temperature is lower than 40 ° C., the developability is increased, and the sensitivity increase (character line width) under high humidity is large, which is not preferable. Moreover, since it becomes higher than 120 degreeC and about the same temperature as heat development temperature, heat transfer is delayed and developability becomes low, which is not preferable.

  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, or an auxiliary layer such as an antihalation dye layer, a so-called backing layer, may be formed on the opposite side. It is good, and a dye or a pigment may be included in the photosensitive layer. These auxiliary layers may contain a slipping agent such as a polysiloxane compound, wax, liquid paraffin in addition to the binder and matting agent.

  In the heat-developable photographic light-sensitive material of the present invention, various surfactants are used as coating aids, and among them, a fluorosurfactant is preferable for improving charging characteristics and preventing spotted coating failure. Used.

  The photosensitive layer of the heat-developable photographic material of the present invention may have a plurality of layers, and in order to adjust gradation, the photosensitive layer is composed of a high-sensitivity layer / low-sensitivity layer, or a low-sensitivity layer / high-sensitivity layer. Anyway.

  An example of a suitable colorant used in the present invention is disclosed in RD No. 17029.

  Antifoggants may be used in the heat-developable photographic light-sensitive material of the present invention, and these additives may be added to any of the photosensitive layer, the intermediate layer, the protective layer and other forming layers.

  For example, surfactants, antioxidants, stabilizers, plasticizers, coating aids and the like may be used in the photothermographic material of the present invention. As these additives and the other additives described above, compounds described in RD No. 17029 (June 1978, p. 9-15) can be preferably used.

[Low heat shrinkable support]
The preferred low heat-shrinkable support of the present invention is used for heat development of a support in order to suppress dimensional change of the plate due to temperature (heat) during heat development when used as a photothermographic material for printing plate making. The absolute value of the dimensional change rate at the corresponding 120 ° C. for 60 seconds is in the range of 0.001 to 0.06% in both the MD (longitudinal) and TD (hand width) directions, preferably 0.001 to 0.04%. Within the range, particularly preferably within the range of 0.001 to 0.02%.

  The measurement of the dimensional change rate in the present invention is performed as follows. That is, the support is marked with a certain length in the MD and TD directions at 23 ° C. and 55% RH, heated to 120 ° C. for 60 seconds, and then again 23 ° C. and 55% After adjusting the humidity for 3 hours under the condition of RH, the length in each direction is measured, and the dimensional change rate is evaluated. The dimension after heating is subtracted from the dimension before heating and divided by the dimension before heating, and the dimensional change rate is expressed as a percentage as a positive value or a negative value.

  The film used as the base material of the support is preferably a thermoplastic resin, and polyester resin is particularly preferable from the viewpoint of mechanical strength, thermal dimensional stability, and transparency. More preferred are aromatic polyester resins, and specific examples include polyethylene terephthalate and polyethylene naphthalate. The thickness of these films is preferably from 50 μm to 500 μm, more preferably from 75 μm to 300 μm, and even more preferably from 90 μm to 200 μm.

  The support of the present invention can be achieved by performing the following heat treatment in order to obtain the above dimensional change rate.

  In the heat treatment according to the present invention, it is desirable to reduce the conveyance tension and lengthen the heat treatment time as much as possible in order to reduce the dimensional change during the subsequent heat treatment (heat development) without hindering the progress of heat shrinkage. The treatment temperature is preferably a temperature range of Tg + 50 to Tg + 150 ° C. of the polyester film, and in that temperature range, the transport tension is preferably 9.8 kPa to 2 MPa, more preferably 9.8 kPa to 980 kPa, and even more preferably 9.8 kPa to It is 490 kPa, and the treatment time is preferably 30 to 10 minutes, more preferably 30 to 5 minutes. By using the above temperature range, conveyance tension range, and processing time, the flatness of the support does not deteriorate due to a partial difference in thermal shrinkage of the support during heat treatment, and fine scratches due to friction with the transfer roll, etc. Etc. can also be suppressed.

  In the present invention, it is also a preferred embodiment that the longitudinal relaxation treatment and / or the lateral relaxation treatment is performed after heat setting before the heat treatment. Moreover, in order to obtain a desired dimensional change rate, the heat treatment is required at least once, and can be performed twice or more as necessary. Further, the heat-treated polyester film is cooled after being cooled from a temperature near Tg to room temperature, and in order to prevent deterioration of flatness due to cooling at this time, at least −5 ° C./second or more until it is lowered to room temperature across Tg. It is preferable to cool at a rate of

  The heat treatment time as the heat treatment condition can be controlled by changing the film conveyance speed or changing the length of the heat treatment zone. If the heat treatment time is too short, the present invention is not effective and the thermal dimensional stability of the support is lowered. Further, if it is 60 minutes or longer, the flatness and transparency of the support are deteriorated, which is not preferable as a support for a heat-developable photographic material. The tension of the heat treatment can be adjusted by adjusting the torque of the take-up roll and / or the feed roll. It can also be achieved by installing a dancer roll in the process and adjusting the load applied to it. When changing the tension during the heat treatment and / or cooling after the heat treatment, a desired tension state may be set by installing dancer rolls before and after these processes and / or in the processes and adjusting their loads. . Further, it is possible to effectively change the conveyance tension by vibration by reducing the span between the heat treatment rolls.

  The support of the present invention is preferably provided with an undercoat layer before providing the silicon oxide thin film. When providing the undercoat layer, acrylic resin, polyester resin, acrylic-modified polyester resin, polyurethane resin, vinylidene chloride resin, polyvinyl alcohol resin, cellulose ester resin, styrene resin, gelatin and the like are preferable. If necessary, triazine-based, epoxy-based, melamine-based, isocyanate-containing isocyanates including blocked isocyanate, aziridine-based, oxazaline-based crosslinking agents, colloidal silica and other inorganic particles, surfactants, thickeners, dyes, antiseptics An agent or the like may be added.

  It is preferable to provide an antistatic layer on the side opposite to the side on which the silicon oxide thin film is provided. The antistatic layer of the present invention is composed of an antistatic agent and a binder.

A metal oxide is preferably used as the antistatic agent. As an example of the metal oxide, ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O ₅ , or a composite oxide thereof is preferable. In particular, SnO ₂ (tin oxide) is preferable from the viewpoints of miscibility with the binder, conductivity, transparency, and the like. As an example including a different element, Sb, Nb, a halogen element or the like can be added to SnO ₂ . The amount of these different elements added is preferably in the range of 0.01 to 25 mol%, particularly preferably in the range of 0.1 to 15 mol%. Tin oxide is preferably in the form of an amorphous sol or crystalline particles. In the case of water-based coating, an amorphous sol is preferable, and in the case of solvent-based coating, the form of crystalline particles is preferable. In particular, from the viewpoint of workability, the form of an amorphous sol with an aqueous coating is preferable from the viewpoint of workability.

As for the method for producing the amorphous SnO ₂ sol, any method such as a method of producing by dispersing SnO ₂ fine particles in an appropriate solvent, or a method of producing from a decomposition reaction of a Sn compound soluble in the solvent in a solvent, etc. But you can. On the other hand, the crystalline particles are described in detail in JP-A-56-143430 and JP-A-60-258541. The conductive metal oxide fine particles can be prepared by first firing the metal oxide fine particles by firing and then heat-treating them in the presence of different atoms to improve conductivity, and secondly by oxidizing the metal oxides by firing. Single and combined methods such as a method of allowing different atoms to coexist at the time of manufacturing fine particles, and a method of introducing an oxygen defect by lowering the oxygen concentration at the time of firing are used.

The average particle diameter of the primary particles of the metal oxide used in the present invention is preferably 0.001 to 0.5 μm, particularly preferably 0.001 to 0.2 μm. The solid amount of the metal oxide used in the present invention is preferably 0.05 to ² g, more preferably 0.1 to 1 g per 1 m ² . The volume fraction of the metal oxide in the antistatic layer in the present invention is 8 to 40 vol%, preferably 10 to 35 vol%. The above range varies depending on the color, shape, composition, etc. of the metal oxide fine particles, but the above range is most preferable from the viewpoint of transparency and conductivity.

  Regarding the binder constituting the antistatic layer, it is preferable to use the same resin as that of the undercoat layer, and polyester, acrylic-modified polyester, acrylic resin, and cellulose ester are particularly preferable from the viewpoint of dispersibility and conductivity of the metal oxide.

  The thickness of the antistatic layer is preferably 0.30 to 0.70 μm from the viewpoint of transparency and coating unevenness (interference unevenness). More preferably, it is 0.35-0.55 micrometer. If it is less than 0.30 μm, the desired high-temperature conductivity is ensured, and the scratch resistance when a BC layer is provided is not preferable. On the other hand, when the thickness is 0.70 μm or more, the interference unevenness is strong and the commercial value is deteriorated, and the transparency is deteriorated and cannot be put into practical use.

  As a coating method for the undercoat layer and the antistatic layer, any known coating method can be applied. For example, kiss coat method, reverse coat method, die coat method, reverse kiss coat method, offset gravure coat method, Mayer bar coat method, roll brush method, spray coat method, air knife coat method, impregnation method, curtain coat method, etc. alone or in combination To apply.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The evaluation methods described in the following examples are as follows.

[Moisture permeability]
The method of measuring moisture permeability was measured according to JIS Z-208 (cup method) with the PET film coated with a moisture-proof layer on the outside of the coated surface.

[Moisture resistance of photographic performance]
(exposure)
A single channel cylindrical inner surface type laser exposure apparatus equipped with a semiconductor laser having a beam diameter (FWHM ½ of the beam intensity) of 12.56 μm, a laser output of 50 mW, and an output wavelength of 783 nm for each of the photothermographic materials produced. Were used under the conditions of a mirror rotation number of 60000 rpm and an exposure time of 1.2 × 10 ⁻⁸ seconds. The overlap coefficient at this time was 0.449, and the laser energy density on the surface of the photothermographic material was 75 μJ / cm ² .

(Heat development)
The development was performed by thermal development using a film processor model 2771 manufactured by Imation at 120 ° C. for 48 seconds. At that time, exposure was performed in a room adjusted to 23 ° C. and 50% RH, and development processing was performed in an environment of 23 ° C., 20% RH, 23 ° C., and 80% RH, respectively.

(Evaluation of photographic performance)
A heat-developable photographic light-sensitive material was prepared at 23 ° C. and 80% RH for 12 hours and a humidity controlled sample at 23 ° C. and 20% RH for 12 hours. Development processing was performed.

  The character line width at high humidity was evaluated by measuring the difference in line width after treatment at 23 ° C. and 20% RH and 23 ° C. and 80% RH. Further, Dmax (maximum concentration) in each environment was also evaluated. Concentration measurement was performed with a Macbeth TD904 densitometer.

[Evaluation of storage stability]
Two parts of a sealed container in which each sample was placed in a container maintained at 25 ° C. and a relative humidity of 55% were prepared, and one of them was stored for 7 days under the condition of 50 ° C. (this is referred to as a forced degradation treated sample). The other was also stored for 7 days under the condition of 25 ° C. for comparison (this is referred to as a comparative sample). Next, each sample was subjected to the same exposure and heat development processing as described above, the minimum density (Dmin) of each processed sample was measured, and the Dmin increase value of the forced degradation treated sample relative to the comparative sample was calculated. A measure of storage stability.

[Scratch resistance test]
Immediately after the heat development process, each sample was attached to a flat, flat surface having no irregularities with the surface of the outermost layer on the photosensitive layer side facing up, and the distance of 10 cm was reciprocated 10 times at a pressure of 100 g / cm ² . . This sample was evaluated according to the following criteria.

○: There is no transmission scratch ○ △: Level at which the transmission scratch appears faint (1-2)
Δ: 1 to 2 transparent scratches are visible Δ ×: 3 to 5 transparent scratches are observed ×: 5 or more transparent scratches are produced [Preparation of Support for Photothermographic Photosensitive Material]
A PET resin was obtained as follows.

(PET resin)
0.05 parts by mass of magnesium acetate hydrate was added as a transesterification catalyst to 100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol, and transesterification was performed according to a conventional method. To the obtained product, 0.05 part by mass of antimony trioxide and 0.03 part by mass of trimethyl phosphate were added. Subsequently, the temperature was gradually raised and reduced, and polymerization was carried out at 280 ° C. and 0.5 mmHg to obtain a polyethylene terephthalate (PET) resin having an intrinsic viscosity of 0.70 (dl / g).

  Using the PET resin obtained as described above, a biaxially stretched PET film with an undercoat layer was produced as follows.

(Biaxially stretched PET film with undercoat)
Pelletized PET resin was vacuum-dried at 150 ° C for 8 hours, melted and extruded from a T-die at 285 ° C in a layered form, closely contacted with electrostatic application on a 30 ° C cooling drum, cooled and solidified, and unstretched A film was obtained. This unstretched sheet was stretched 3.3 times in the longitudinal direction at 80 ° C. using a roll type longitudinal stretching machine. The following undercoating liquid A (solid content: 4% by mass) was applied to the obtained uniaxially stretched film by a kiss coating method so that the WET film thickness was 2 g / m ² . Subsequently, using a tenter-type transverse stretching machine, the film was stretched to 50% of the total transverse stretching ratio in the first stretching zone 90 ° C., and further stretched to a total transverse stretching ratio of 3.3 times in the second stretching zone 100 ° C. . Subsequently, pre-heat treatment was performed at 70 ° C. for 2 seconds, and heat setting was further performed at the first fixing zone 150 ° C. for 5 seconds, and heat setting was performed at the second fixing zone 220 ° C. for 15 seconds. Next, 5% relaxation treatment is performed in the lateral (width) direction at 160 ° C. After exiting the tenter, the relaxation treatment is performed in the longitudinal (longitudinal) direction at 140 ° C. using the peripheral speed difference of the drive roll, until the room temperature is reached. After cooling for 60 seconds, the film was released from the clip, slitted, and wound up to obtain a biaxially stretched PET film having a thickness of 125 μm. The biaxially stretched PET film had a Tg of 79 ° C.

<Undercoat coating liquid A>
Acrylic copolymer 40 parts by weight Compound (G) 50 parts by weight Polyglycerin 10 parts by weight Finished with pure water so that the total solid content in the coating solution was 4%.

  Acrylic copolymer: methyl methacrylate / ethyl acrylate / acrylic acid / hydroxyethyl methacrylate / acrylamide = 30 / 47.5 / 10 / 2.5 / 10, mass average molecular weight 500,000

(Heat treatment of support)
Using a suspension type thermal relaxation apparatus, relaxation heat treatment was performed under the conditions of temperature: 180 ° C., transport tension: 230 kPa, time: 15 sec, and further cooled to room temperature at 10 ° C./min, and then wound.

(Antistatic layer)
The following undercoat coating solution B was applied to the heat-treated support with a wire bar so as to have a dry film thickness of 0.35 μm, and dried at 80 ° C. for 2 minutes to prepare a support with an antistatic layer.

<Undercoat coating solution B>
Tin oxide sol (SnO ₂ sol synthesized by the method described in Example 1 of JP-B-35-6616 was heated and concentrated so that the solid content concentration was 8.3% by mass, and then adjusted to pH = 10 with ammonia water. 500g
Acrylic modified polyester resin (B-1 described in JP-A No. 2002-156730: solid content: 17.8% by mass) 200 g
300 g of water
[Preparation of Photothermographic Photothermographic Material]
(Application on the back layer side)
The back layer coating solution and the back protective layer coating solution having the following composition were filtered using a filter having an absolute filtration accuracy of 20 μm before coating, respectively, and then the total wet film was formed on the prepared antistatic support with an extrusion coater. A simultaneous multilayer coating was applied at a speed of 50 m / min so that the thickness was 60 μm, and drying was performed at 70 ° C. for 4 minutes.

<Back layer coating solution>
Methyl ethyl ketone 16.4 g / m ²
Dye B 17 mg / m ²
Stabilizer B-1 (Sumitomo Chemical Company Sumitizer BPA) 20 mg / m ²
Stabilizer B-2 (Yoshitomi Pharmaceutical Tomissorb 77) 50 mg / m ²
Cellulose acetate propyleneate (Eastman Chemical CAP504-0.2) 0.5 g / m ²
Cellulose Acetate Propylate (Eastman Chemical CAP482-20) 1.5 g / m ²
Fluorine-based surfactant: C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₂ C ₉ F ₁₇ 20 mg / m ²
Fluorosurfactant: C ₈ F ₁₇ SO ₃ Li 100 mg / m ²
<Back protective layer coating solution>
Methyl ethyl ketone 22g / m ²
Fluorine-based surfactant: C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₂ C ₉ F ₁₇ 22 mg / m ²
Fluorosurfactant: C ₈ F ₁₇ SO ₃ Li 10 mg / m ²
Cellulose acetate propinate (Eastman Chemical CAP482) 2.0 g / m ²
Silica (Fuji Devison Psyroid 74; average particle size 7 μm) 12 mg / m ²

(Preparation of silver halide grains)
In 900 ml of pure water, 7.5 g of gelatin and 10 mg of potassium bromide were dissolved, adjusted to a temperature of 35 ° C. and a pH of 3.0, and then brominated at a molar ratio of (96/4) with 370 ml of an aqueous solution containing 74 g of silver nitrate. An aqueous solution containing 5 × 10 ⁻⁶ mol / liter of potassium, potassium iodide and (NH ₄ ) ₂ RhCl ₅ (H ₂ O) was added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with 1 M / L NaOH aqueous solution, the average particle size was 0.06 μm, and the projected diameter was Silver halide grains composed of cubic silver iodobromide having an area variation coefficient of 8% and a {100} face ratio of 86% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant, desalted and then 0.1 g phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5.

(Preparation of organic fatty acid silver emulsion)
10.6 g of behenic acid was placed in 300 ml of water, dissolved by heating at 90 ° C., 31.1 ml of 1 M / L sodium hydroxide was added with sufficient stirring, and the mixture was left as it was for 1 hour. Thereafter, the mixture was cooled to 30 ° C., 7.0 ml of 1 M / L phosphoric acid was added, and 0.01 g of N-bromosuccinimide was added with sufficient stirring. Thereafter, silver halide grains prepared in advance were added with stirring in a state heated to 40 ° C. so that the amount of silver was 10 mol% with respect to behenic acid. Further, 25 ml of 1 M / L silver nitrate aqueous solution was continuously added over 2 minutes, and the mixture was left for 1 hour with stirring.

  To this emulsion, polyvinyl butyral dissolved in ethyl acetate was added and stirred sufficiently, and then allowed to stand to separate into an ethyl acetate phase containing silver behenate grains and silver halide grains and an aqueous phase. After removing the aqueous phase, silver behenate particles and silver halide particles were collected by centrifugation. Thereafter, 20 g of synthetic zeolite A-3 (spherical) manufactured by Tosoh Corp. and 22 ml of isopropyl alcohol were added and left for 1 hour, followed by filtration. Further, 3.4 g of the binder shown in Table 1 and 23 ml of isopropyl alcohol were added, and the mixture was sufficiently stirred and dispersed at 35 ° C. at high speed to complete the preparation of the organic fatty acid silver emulsion.

(Photosensitive layer Em composition)
Organic fatty acid silver emulsion 1.4g (in silver) / m ²
Pyridinium hydrobromide perbromide 1.5 × 10 ⁻⁴ mol / m ²
Calcium bromide 1.8 × 10 ⁻⁴ mol / m ²
2- (4-Chlorobenzoyl) benzoic acid 1.5 × 10 ⁻³ mol / m ²
Infrared sensitizing dye 1 4.2 × 10 ⁻⁶ mol / m ²
2-mercaptobenzimidazole 3.2 × 10 ⁻³ mol / m ²
2-Tribromomethylsulfonylquinoline 6.0 × 10 ⁻⁴ mol / m ²
4-methylphthalic acid 1.6 × 10 ⁻³ mol / m ²
Tetrachlorophthalic acid 7.9 × 10 ⁻⁴ mol / m ²
1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane 4.8 × 10 ⁻³ mol / m ²
Dye A 3 × 10 ⁻⁵ mol / m ²
Nucleating agent: see Table 1 0.5 × 10 ⁻³ mol / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

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

Cellulose Acetate Butyrate (Eastman Chemical CAP381-20) / Cellulose Acetate Propinate (Eastman
Chemical CAP504-05) = 2/8 4 g / m ²
Phthalazine 3.2 × 10 ⁻³ mol / m ²
Silica (Fuji Devison Psyroid 74; average particle size 7 μm) 100 mg / m ²
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Application of moisture barrier)
A coating solution was prepared so as to be a moisture-proof layer having the composition shown in Table 1, filtered using a filter having an absolute filtration accuracy of 20 μm, and then wet coated on the surface protective layer side of the photothermographic photosensitive material prepared by wire bar coating. The film was applied at a speed of 30 m / min so as to have a film thickness of 15 μm and a dry film thickness of 3 μm, and dried at 70 ° C. for 4 minutes.

Moisture-proof layer X
Latex A (30%) 29g
Latex B (30%) 29g
Wax A (45%) 2.4 g
Element F activator (1% water / methanol: 1/1) 18 g
Silica 1 dispersion (1%) 7g
Silica 2 dispersion (1%) 13g
Finish to 100 g with pure water.

Moisture-proof layer Y
Latex A (30%) 29g
Latex B (30%) 29g
Wax B (45%) 2.4g
Element F activator (1% water / methanol: 1/1) 18 g
Silica 1 dispersion (1%) 7g
Silica 2 dispersion (1%) 13g
Finish to 100 g with pure water.

Latex A: Styrene / butyl acrylate / glycidyl methacrylate (20:40:40) (Tg = 20 ° C.)
Latex B: Styrene / butyl acrylate / glycidyl methacrylate (40:20:40) (Tg = 45 ° C.)
Wax A: Nippon Seiwa Co., Ltd. EMUSTAR-0185 (melting point: 80 ° C.) Paraffin Wax B: Nippon Seiwa Co., Ltd. EMUSTAR-0413 (melting point: 83 ° C.) Carnaba F element Activator: Neos Co., Ltd.
Silica 1: Silica (Fuji Devison Psyroid 266; average particle size 3 μm)
Silica 2: Silica (Fuji Debison Psyroid 74; average particle size 7 μm)

  From Table 1, it is shown that the sample in which the photothermographic material is produced using the support for the photothermographic material of the present invention has good photographic performance (density, sensitivity) humidity resistance, storage stability, and scratch resistance. I understand.

Claims (7)

In a photothermographic material having a photosensitive layer containing organic silver salt grains, silver halide grains and a reducing agent on a support, the photosensitive layer contains at least two compounds represented by the following general formula (1). A heat-developable photographic light-sensitive material containing an outermost layer on the photosensitive layer side, which is a moisture-proof layer composed of a latex and a wax emulsion.

[Wherein R ₁₁ , R ₁₂ and R ₁₃ each represent a hydrogen atom or a monovalent substituent, and X ₁₁ represents an electron-donating heterocyclic group, cycloalkyloxy group, cycloalkylthio group, cycloalkylamino group or Represents a cycloalkenyl group. ] The compound represented by the general formula (1) is characterized in that the substituent represented by R ₁₁ is a cyano group, and the substituent represented by R ₁₂ or R ₁₃ is a hydroxyl group. The photothermographic material described in 1. 3. The photothermographic material according to claim 1, wherein at least one of the compounds represented by the general formula (1) is such that the electron attractive group represented by X ₁₁ is a heterocyclic group. . 4. The photothermographic material according to claim 1, wherein the wax emulsion is paraffinic. The photothermographic material according to claim 1, wherein the photosensitive layer and the outermost layer are formed by solvent coating. 6. The photothermographic material according to claim 1, wherein the moisture-proof layer has a moisture permeability of 1 to 40 g / m ² · 24 hr. 7. The photothermographic material according to claim 1, wherein the support is a low heat shrinkable support.