JP2005121923A - Heat developable photographic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photographic material free of the occurrence of unevenness in spite of so-called good sharpness and having improved moisture resistance particularly as a material for printing and platemaking. <P>SOLUTION: In the heat developable photographic material which has a photosensitive layer containing organic silver salt grains, silver halide grains, and a reducing agent on a support and is imagewise exposed to light of ≤500 nm wavelength, a moisture-proof layer consisting of latex and a wax emulsion is located as an outermost layer on the photosensitive layer side and the glossiness of the moisture-proof layer is 15-35. <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 both sharpness and unevenness and improved humidity resistance for printing plate making.

  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 as well, from the viewpoint of environmental conservation and space saving, it is possible to efficiently expose with a laser scanner or laser image setter without forming processing waste liquid, and to form a clear black image with high resolution. There is a strong interest in photothermographic materials.

  For example, US Pat. Nos. 3,152,904, 3,457,075, and D.W. Morgan and B.M. Shery, “Thermally Processed Silver Systems A” (Imaging Processes and Materials), 8th edition, page 2, 1969. Has been described.

  On the other hand, in recent years, image information has been digitized and stored, and after being image-processed or transmitted over a network as necessary, the image is laser output to a photosensitive material at a desired location. The forming system is spreading. In particular, medical images and characters and images for printing plate making are rapidly digitized and are being digitized accordingly.

  As the laser light source, coherent light such as argon, helium-neon, helium-cadmium, etc. is used, but these laser tubes all have a short life and need to use a dedicated driver for the high-voltage power supply. It has drawbacks such as inevitable enlargement. In addition, all of the semiconductor lasers provided so far have a long emission wavelength of 650 nm or more, and silver halide photographic light-sensitive materials having photosensitivity in this region are inferior in storage stability and being stored. In addition, there was a drawback that fogging and desensitization were easy. This defect is thought to be due to the instability factor of the spectral sensitizing dye.

  Recently, a module in which an SHG (Second Hermogen Generator) element and a semiconductor laser are integrated and a blue semiconductor laser have been developed, and a laser output device in a short wavelength region has been closed up. Blue semiconductor lasers are expected to grow in demand in the future because high-definition image recording and recording density can be increased, and long-life and stable output can be obtained.

  Therefore, in order to provide a high-sensitivity photothermographic material corresponding to a blue laser of 500 nm or less, a photothermographic material that is sensitive to the short wavelength is provided by adjusting the AgI content in the silver halide grains. Technology is being developed (Patent Document 1 and Patent Document 2). However, although the so-called sharpening is improved by the short wavelength of the photosensitive region, it has been found that unevenness is deteriorated by that amount, and in the case of printing plate making, there is a problem that unevenness is seen on the printed matter.

  On the other hand, in the photothermographic material, the moisture content in the light-sensitive material decreases during the low humidity period in winter, and the development reaction does not proceed easily. There are problems that the development reaction tends to proceed, the sensitivity becomes too high, and the character line width becomes thick.

Conventional technologies include the use of vinylidene chloride for the protective layer to reduce the influence of character line width under high humidity (Patent Document 3), and the use of vinylidene chloride for the undercoat to reduce the influence of humidity on dimensional performance. A technique (Patent Document 4) is known. However, these technologies have problems in environmental measures. Also known is a technique for thickening the protective layer (Patent Document 5) for securing the concentration during low-humidity storage and a technique for changing the drying temperature to reduce the influence of the character line width under high humidity (Patent Document 6). It has been. However, each technique has only an improvement effect that is insufficient to solve practical problems.
JP 2003-91053 A JP 2003-162025 A JP 2001-272742 A JP 2001-287298 A JP 2001-249425 A JP 2002-55413 A

  An object of the present invention is to provide a photothermographic material having improved humidity resistance, which is so-called sharp and has no unevenness, especially for printing plate making. is there.

  As a result of intensive studies on the above problems, the present inventor has installed a layer composed of latex and a wax emulsion in the outermost layer on the photosensitive layer side in order to achieve both surface glossiness and moisture resistance. It was found that a heat-developable photographic light-sensitive material having excellent humidity resistance in photographic performance can be obtained.

That is, it has been found that the object of the present invention is achieved by adopting any of the following configurations.
(Claim 1)
In a photothermographic material having a photosensitive layer containing organic silver salt particles, silver halide particles and a reducing agent on a support and image-exposed with light having a wavelength of 500 nm or less, the outermost layer on the photosensitive layer side A photothermographic material having a moisture-proof layer composed of a latex and a wax emulsion, wherein the moisture-proof layer has a glossiness of 15 to 35.
(Claim 2)
^{2. 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 3)
3. The photothermographic material according to claim 1, wherein the wax emulsion is paraffinic.
(Claim 4)
4. The photothermographic material according to claim 1, wherein the photosensitive layer contains a nucleating agent.
(Claim 5)
5. The photothermographic material according to claim 1, wherein the support is a low heat shrinkable support.

  According to the present invention, it is possible to provide a photothermographic material having improved humidity resistance, which is good for so-called sharpness, and does not cause unevenness, particularly for printing plate making.

  The present invention will be described in detail below.

[Glossiness]
The glossiness was measured with a gloss meter VGS-1D (manufactured by Nippon Denshoku Industries Co., Ltd.) at an incident angle of 60 ° in a pre-exposure sample of the heat-developable photographic photosensitive material.

  If the glossiness is 15 to 35, the photo image has a three-dimensional effect due to moderate gloss, and the characters are easy to read.

  In the present invention, the glossiness of the outermost layer on the photosensitive layer side is 15 to 35, more preferably 23 to 35. When the glossiness is greater than 35 or less than 15, absorption, reflection and refraction of light having a short wavelength of 500 nm or less are increased, so-called sharpness is deteriorated, and uneven density tends to occur.

  The glossiness of 15 to 35 in the present invention can be achieved by adjusting the outermost layer on the photosensitive layer side = latex and wax of the moisture-proof layer and, if necessary, the type and addition amount of the matting agent.

[Dampproof layer]
The moisture-proof layer of the present invention is the outermost layer on the photosensitive layer side and is composed of latex and wax emulsion. The ratio of latex to emulsion is preferably 100: 2 to 100: 100. More preferably, it is 100: 10-100: 50. If the amount of the wax emulsion is decreased from 100: 2, the moisture-proof effect is not exhibited, and the humidity resistance of the photothermographic material is deteriorated. On the other hand, when the amount of the wax emulsion exceeds 100: 100, the film as the moisture-proof layer becomes weak and the blocking property 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. In order to make it 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 blocking property 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 photothermographic material may be deteriorated.

  In addition, the measuring method of moisture permeability can be measured according to JIS Z-208 (cup method).

〔latex〕
The type of latex of the present invention is not particularly limited, but synthetic resin-based or synthetic rubber-based latex is preferable in terms of moisture resistance due to blocking resistance and film-forming properties, and in particular, synthetic resin-based latex. Are preferred.

  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. There are things, and any of them 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 membrane and the blocking property 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 preferably about 1 to 50,000 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, amphoteric 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. Among these, the compound having the following structural formula shown in JP-A-58-203960 is most preferable.

  The synthetic resin latex is produced as a copolymer by homopolymers or combinations of the following ethylenically unsaturated monomers. 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 butadiene, 1,3 butadiene 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 monoacrylic 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 of ethylenically unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate Esters and acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-butoxymethyl acrylamide, diacetone acrylimide, 2-acetoacetoxyethyl methacrylate, 2-acetoacetoxyethyl acrylate, 2-acetate Examples thereof include radically polymerizable monomers such as acetoacetoxy ester having an active methylene group such as acetoxypropyl methacrylate and 2-acetoacetoxypropyl acrylate.

  Among them, those having a functional group capable of chemical bonding are preferable for improving humidity resistance and scratch resistance. Particularly preferred are those having a glycidyl group and those having an active methylene group.

  It is preferable that it is 5 to 80% of the latex component to comprise as a functional group, More preferably, it is 20 to 60%. If it is less than 5%, humidity resistance and scratch resistance may be insufficient. On the other hand, if it exceeds 80%, the stability of the latex deteriorates and there is a possibility that it may be hindered by coating.

[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, Fisher tribush wax, polyethylene wax, montan wax and derivatives thereof, and microcrystalline. Examples thereof include waxes and derivatives thereof, hardened castor oil, liquid paraffin, stearamide, 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.

(Matting agent)
In the present invention, a matting agent is preferably used for the outermost layer. As the shape, spherical, needle-like, flat plate-like, and scale-like ones are used, but spherical and needle-like ones are preferable, and spherical ones are particularly preferable. In the case of a spherical shape, the average particle size is 0.01 to 6 μm, preferably 0.05 to 4 μm. As addition amount, it is 0.1-20 mass% with respect to the binder in a layer, Preferably it is 0.5-10 mass%, More preferably, it is 1-5 mass%.

  The matting agent used in the present invention preferably has a dispersion uniformity of 60% or more. The dispersion uniformity referred to here is a ratio (%) of particles falling within ± 10% of the average particle diameter. Particularly preferably, it is 80% or more, more preferably 90% or more.

  The matting agent useful in the present invention may be inorganic fine particles or organic polymer fine particles, but those that do not deform when thermally developed at 80 to 140 ° C. are preferred. As a result, the inventor estimates that absorption, reflection, refraction, and the like of light having a short wavelength of 500 nm or less are less likely to occur, and density unevenness is less likely to occur.

  As the inorganic fine particle matting agent useful in the present invention, those having a structure of an inorganic compound described in Chemical Dictionary 9 (Kyoritsu Shuppan), page 312 (Showa 43 miniprint) can be used. .

For example, the inorganic fine particles _{CaCO 3, CaSO 4, ZnS,} BaSO 4, MgCO 3, CaF 2, ZnO, ZnCO 3, TiO 2, SnO 2, SiO 2, Al 2 O 3 or the like can be mentioned, these It may be a composite metal compound. For example, SiO ₂ hydrolyzes ethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ ) to produce hydrous silica (Si (OH) ₄ ), and further forms hydrous silica monodisperse spheres. A silica matting agent can be produced by forming a silica bond that is three-dimensionally grown by dehydration. In the present invention, a matting agent made of silica is particularly preferable.

  The organic matting agent used in the present invention has an average particle size of 0.5 to 20 μm. If the average particle size is smaller than 1 μm, the mat effect cannot be exhibited and the scratch resistance is deteriorated. On the other hand, if the average particle size is larger than 20 μm, the dispersion stability in the matting agent dispersion and / or the moisture-proof layer coating solution is poor, and the matting agent particles are agglomerated, which is not preferable. Especially preferably, it is 1-15 micrometers, More preferably, it is 2-10 micrometers.

  In the present invention, the organic matting agent is more advantageous than the inorganic matting agent because the difference in expansibility from the moisture-proof layer during heat development is smaller than that of inorganic particles, and this causes distortion during transportation. There is a point that it is possible to follow and it is estimated that scratches and the like are hardly attached.

  The average particle size referred to here is an average of values obtained by photographing a sample with an electron microscope and measuring the diameter of each particle. Examples of the resin constituting the matting agent include acrylic resin, polyester resin, polyurethane resin, vinyl chloride resin, vinylidene chloride resin, rubber-based resin (for example, SBR rubber, NBR rubber), vinyl acetate resin, polyolefin resin, polyvinyl acetal. Examples thereof include pulverized and classified products such as resins and polymer compounds such as starch. As the organic compound matting agent, a polymer compound synthesized by a suspension polymerization method or a polymer compound made spherical by a spray drying method or a dispersion method can be used.

  The resin may be a homopolymer obtained by polymerizing a single monomer or a copolymer obtained by polymerizing two or more kinds of polymers. The polymer may be linear or branched. Further, it may be cross-linked.

Next, specific examples of the polymer used for the matting agent of the organic compound are shown.
1. -MMA (100)-
2. -MMA (95) -AA (5)-
3. -2EHA (30) -MMA (50) -St (15) -MAA (5)-
4). -BR (50)-St (47)-AA (3)-
5). -BR (40)-DVB (10)-St (45)-MAA (5)-
6). -VC (70)-MMA (25)-AA (5)-
7). -VDC (60) -MMA (35) -MAA (5)-
8). -PS (100)-
9. -PS (80)-MMA (20)-
10. -PS (95)-AA (5)-
11. -PS (80)-MMA (20)-MAA (5)-
In the above, MMA is derived from methyl methacrylate, AA is acrylic acid, 2EHA is 2-ethylhexyl acrylate, St is styrene, MAA is methacrylic acid, BR is butadiene, DVB is divinylbenzene, VC is vinyl chloride, and VDC is derived from vinylidene chloride. The numerical value in parentheses is% by mass.

  The matting agent of the present invention preferably has a dispersion uniformity of 60% or more. The dispersion uniformity referred to here is a ratio (%) of particles falling within ± 10% of the average particle diameter. When the dispersion uniformity is 60% or more, the mat effect can be sufficiently exhibited, and the scratch resistance is improved. Particularly preferably, it is 80% or more, more preferably 90% or more.

[Others]
The moisture-proof layer of the present invention preferably contains a fluorinated surfactant in order to adjust coating properties and charging properties. The fluorosurfactant may be any of anionic, cationic and nonionic, and among them, anionic ones are preferable. These may be low molecular compounds or high molecular compounds.

  You may use a crosslinking agent for the moisture-proof layer of this 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 that can be used in the present invention includes various crosslinking agents conventionally used for photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, described in JP-A-50-96216, Vinyl sulfone type, sulfonic acid ester type, acryloyl type and carbodiimide type cross-linking agents may be mentioned.

(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: Salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.); silver carboxyalkylthiourea salts (eg, 1- (3-carboxypropyl) thiourea, 1 -(3-carboxypropyl) -3,3-dimethylthiourea, etc.); silver complex of polymer reaction product of aldehyde and hydroxy-substituted aromatic carboxylic acid (eg aldehydes such as formaldehyde, acetaldehyde, butyraldehyde and salicylic acid) , Benzylic acid 3,5-dihydroxybenzoic acid, hydroxy-substituted acids such as 5,5-thiodisalicylic acid); silver salts or complexes of thiones (eg 3- (2-carboxyethyl) -4-hydroxymethyl- 4-thiazoline-2-thione and 3-carboxymethyl-4-methyl-4-thiazoline 2-thione); nitrogen acid and silver selected from imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole Or a salt thereof; silver salts such as saccharin and 5-chlorosalicylaldoxime; silver salts of mercaptides and the like. 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. The average grain size of the silver halide grains was measured at 50000 times with an electron microscope, the long side and the short side of each silver halide grain were measured, and 100 grains were measured and averaged. Is 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.

  Preferred silver halide grains used in the present invention are high silver bromide emulsions having a halogen composition of 40 to 100 mol% because of having photosensitivity at a short wavelength of 500 nm or less. The remaining 60 mol% is not particularly limited and can be selected from silver chloride, silver bromide and silver iodide, but silver iodide is particularly preferable. By using such a high silver bromide emulsion, a high-sensitivity photothermographic material can be designed. From the viewpoint of sensitivity, the silver bromide content is more preferably 70 to 100 mol%, still more preferably 80 to 100 mol%, and particularly preferably 90 to 100 mol%. The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles. A core high silver bromide structure or a shell high silver bromide structure can also be preferably used. A technique of localizing silver iodide on the surface of the grain can also be preferably used.

  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. By Glafkides Chimie et Physique Photographic (published by Paul Montel, 1967), G. 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.

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, etc. and RD Nos. 17029 and 29963, and the followings are 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); hydrazones of aldehydes or ketones (eg, anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (E.g. hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (e.g. 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-tert-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 toning agent contained in the photosensitive layer of the heat-developable photographic material of the present invention includes, as a hydrazine compound, RD 23515 (November 1983, P. 346) and the literature cited therein, as well as the United States. Patent Nos. 4,080,207, 4,269,929, 4,276,364, 4,278,748, 4,385,108, 4,459 347, 4,478,928, 4,560,638, 4,686,167, 4,912,016, 4,988,604, No. 4,994,365, No. 5,041,355, No. 5,104,769, British Patent No. 2,011,391B, European Patent No. 217,310, No. 301,799 No. 356,898, JP-A-60-179734 61-170733, 61-270744, 62-178246, 62-270948, 63-29751, 63-32538, 63-104047, 63-121838, 63 -129337, 63-223744, 63-234244, 63-234245, 63-234246, 63-294552, 63-306438, 64-10233, JP-A-1- 90439, 1-100530, 1-105941, 1-150943, 1-276128, 1-280747, 1-283548, 1-283549, 1-285940 2-2541, 2-77057, 2-139538, 2-196234, 2 No. 196235, No. 2-198440, No. 2-198441, No. 2-198442, No. 2-220042, No. 2-221953, No. 2-221954, No. 2-285342, No. 2-285343 2-289843, 2-302750, 2-304550, 3-37642, 3-54549, 3-125134, 3-184039, 3-240036, 3-240037, 3-259240, 3-280038, 3-282536, 4-511436, 4-568842, 4-84134, 2-230233, 4- 96053, 4-216544, 5-45761, 5-45762, 5-45763, 5-45764, 5-45 No. 765, No. 6-289524, No. 9-160164 and the like.

  In addition, compounds represented by (Chemical Formula 1) described in JP-B-6-77138, specifically, compounds described on pages 3 and 4 of the same publication, JP-B-6-93082 Compounds represented by the general formula (1) described in the above, specifically, compounds 1 to 38 described on pages 8 to 18 of the same publication, general formula (4) described in JP-A-6-23049 , (5) and (6), specifically, compounds 4-1 to 4-10 described on pages 25 and 26 of the same publication, and compounds 5-1 described on pages 28 to 36 -5-42, and compounds 6-1 to 6-7 described on pages 39 and 40, and compounds represented by general formulas (1) and (2) described in JP-A-6-289520, specifically Specifically, compounds 1-1) to 1-17) and 2-1) described on pages 5 to 7 of the same publication, and JP-A-6-313936. The compounds represented by (Chemical Formula 2) and (Chemical Formula 3) listed above are specifically compounds described on pages 6 to 19 of the same publication, and represented by (Chemical formula 1) described in JP-A-6-313951. Specifically, compounds described on pages 3 to 5 of the same publication, compounds represented by the general formula (I) described in JP-A-7-5610, specifically, Compounds I-1 to I-38 described on pages 5 to 10 and compounds represented by the general formula (II) described in JP-A-7-77783, specifically, pages 10 to 27 Compounds II-1 to II-102, and compounds represented by general formula (H) and general formula (Ha) described in JP-A-7-104426, specifically, pages 8 to 15 of the same publication. Those described in the compounds H-1 to H-44 described on the page can be used.

  Furthermore, as other contrast-increasing agents used in the present invention, compounds described on pages 33 to 53 of JP-A No. 11-316437 are preferably used.

  The amount of the high contrast agent contained in the photothermographic material of the present invention is preferably from 0.1 to 0.001 mol, more preferably from 0.05 to 0.005 mol, per 1 mol of silver.

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.

[Support]
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 a desired dimensional change rate.

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

  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 to 980 kPa, and even more preferably 9.8 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 more, the flatness and transparency of the support are deteriorated, which is not preferable as the support for the photothermographic 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 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.

[Glossiness]
The glossiness was measured with a gloss meter VGS-1D (manufactured by Nippon Denshoku Industries Co., Ltd.) at an incident angle of 60 ° in a pre-exposure sample of the photothermographic material.

  The glossiness was determined as follows based on whether or not the photographic image had a three-dimensional effect due to moderate gloss and whether the characters were easy to read.

A: Glossiness 23-35
○: Glossiness of 15 to less than 23 ×: Glossiness of less than 15 or more than 35 [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 and 23 ° C. 80% RH, respectively.

(Evaluation of photographic performance)
A photothermographic material was prepared for humidity control at 23 ° C. and 80% RH for 12 hours, and sample prepared for humidity control at 23 ° C. and 20% RH for 12 hours, and a line width exposure of 50 μm was performed in the same environment. Then, heat 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 50% 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.

[Photo performance sharpness and unevenness]
(exposure)
Each of the photothermographic materials thus produced was exposed with xenon flash light having a light emission time of 10 ⁻⁶ seconds through a step wedge through an interference filter having a peak at 410 nm.

(Heat development)
The development was performed by thermal development using a film processor model 2771 manufactured by Imation at 120 ° C. for 48 seconds.

(Evaluation of sharpness: measurement of γ)
Each of the prepared heat-development-treated samples was measured with an optical densitometer (PD-6 manufactured by Konica Corporation) through a filter that cuts light of 420 nm or more, and the horizontal axis—exposure (Log E), the vertical axis—optical density. A characteristic curve consisting of (D) was prepared. The slope (tan θ) of the straight line connecting the optical density points 0.3 and 3.0 in the obtained characteristic curve was defined as γ.

(Evaluation of uneven density after heat development)
The density unevenness after the heat development processing is evaluated visually according to the following five-level rank, and the results are shown in Table 4.
Rank 1: Strong density unevenness occurs on the entire surface Rank 2: Strong density unevenness occurs on a part Rank 3: Some density unevenness occurs on a small scale Rank 4: Slight density unevenness occurs Rank 5: Generation of density unevenness is observed In the above evaluation, ranks 4 and 5 were determined to be practically acceptable levels.

[Preparation of support for photothermographic 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 the pressure was 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.

  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 layer)
Pelletized PET resin is 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 cooling drum at 30 ° C, 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.

Undercoating 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, weight 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 undercoat coating liquid 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.

Undercoating liquid 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-2002-156730: solid content: 17.8% by mass) 200 g
300 g of water
[Preparation of photothermographic material]
(Application on the back layer side)
The back layer coating solution 1 and the back protective layer coating solution 1 having the following composition were filtered using a filter having an absolute filtration accuracy of 20 μm before coating, respectively, and then the total amount was applied to the prepared antistatic support using an extrusion coater. Simultaneous multilayer coating was performed at a rate of 50 m / min so that the wet film thickness was 60 μm, and drying was performed at 70 ° C. for 4 minutes.

<Back layer coating solution 1>
Methyl ethyl ketone 16.4 g / m ²
Dye-A 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 propylate (Eastman Chemical CAP504-0.2) 0.5 g / m ²
Cellulose Acetate Propylate (Eastman Chemical CAP482-20) 1.5 g / m ²

<Back protective layer coating solution 1>
Methyl ethyl ketone 22g / m ²
Fluorine-based surfactant F-1: C ₉ F ₁₇ (CH ₂ CH ₂ O) OC ₉ F ₁₇ 22 mg / m ²
Fluorine-based surfactant F-1: 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 emulsion A)
Silver bromide grains prepared as described below were dissolved by heating at 38 ° C., and 7 × 10 ⁻³ mol of benzothiazolium iodide was added as a 1% by mass aqueous solution per mol of silver. Further, water was added to adjust the amount of silver contained in 1 kg to 38.2 g.

(Preparation of silver bromide emulsion B)
In 700 ml of water, 11 g of alkali-treated gelatin (calcium content of 2,700 ppm or less), 30 mg of potassium bromide and 1.3 g of sodium 4-methylbenzenesulfonate were dissolved, and the pH was adjusted to 6.5 at a temperature of 40 ° C. after silver nitrate 18.6g aqueous solution containing 159ml of potassium bromide and _{1mol / L, (NH 4)} 2 RhCl 5 (H 2 O) to 5 × 10 ^-6 mol / L and K ₃ IrCl ₆ to 2 × 10 ^{- An} aqueous solution containing ⁵ mol / L was added over 6 minutes 30 seconds by the control double jet method while maintaining pAg 7.7.

Then, 476 ml of an aqueous solution containing 55.5 g of silver nitrate and a halogen salt aqueous solution containing potassium bromide at 1 mol / L and K ₃ IrCl ₆ at 2 × 10 ⁻⁵ mol / L were maintained at 28 pAg 7.7 by a control double jet method. Added over 30 minutes. Thereafter, the pH was lowered to cause coagulation sedimentation, and desalting treatment was performed to obtain cubic silver halide grains having an average grain size of 0.08 μm, a projected area variation coefficient of 9%, and a (100) plane ratio of 90%. 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 1M sodium hydroxide was added with sufficient stirring, and the mixture was left as it was for 1 hour. After cooling to 30 ° C., 7.0 g of 1M 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 1M 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 Corporation and 22 ml of isopropyl alcohol were added and left to stand for 1 hour, followed by filtration. Further, 23 ml of isopropyl alcohol was 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 emulsion coating solution 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
Sensitizing dye 1-6 (added as a methanol solution to 1 mol of silver halide)
3.0 × 10 ⁻³ mol
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
Nucleator C-65 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
As the solvent, methyl ethyl ketone, acetone, and methanol were appropriately used.

(Application of moisture barrier)
After preparing a coating solution to be a moisture-proof layer so that the material shown below has a 1000 ml finish, and filtering using a filter with an absolute filtration accuracy of 20 μm, the surface protective layer of the photothermographic material prepared above with a wire bar coater On the side, it was applied at a rate of 30 m / min so as to have a wet film thickness of 15 μm and a dry film thickness of 3 μm, and dried at 70 ° C. for 4 minutes.

10g of pure water
Latex (30% by mass) See Table 1 Wax emulsion (40% by mass) See Table 1 Fluoroactive agent A; C ₉ F ₁₉ -C ₉ H ₄ -SO ₃ K (added to 20 mg / m ² )
Matting agent See Table 1 Fluoroactive agent A:

Matting agent type SI: Silica (Fuji Devison Psyroid 74X6000; average particle size 6 μm)
SY: Silicone (Tospearl 5 μm, dispersion uniformity 90%)
PMS: PMMA-styrene resin (average particle size 6 μm, dispersion uniformity 60%)
Latex type Latex 1: Styrene-butyl acrylate-glycidyl methacrylate = 20: 40: 40 (Tg = 20 ° C.)
Latex 2: Styrene-butyl acrylate-glycidyl methacrylate-acetoacetoxyethyl methacrylate = 39.5: 0.5: 40: 20 (Tg = 45 ° C.)
Latex 3: Styrene-butyl acrylate-glycidyl methacrylate-acetoacetoxyethyl methacrylate = 39.5: 19.5: 40: 0.5 (Tg = 40 ° C.)
Wax species A: Nippon Seiwa Co., Ltd. EMUSTAR-0135 (melting point: 61 ° C.) Paraffin wax I: Nippon Seiwa Co., Ltd. EMUSTAR-0413 (melting point: 83 ° C.) Carnauba wax From Table 1, the photothermographic material of the present invention It can be seen that the sample in which the photothermographic material was produced using the support for the photo has good photographic performance (density, sensitivity) humidity resistance, sharpness and unevenness.

  As is clear from the results, the photothermographic material for photothermographic materials of the present invention has little variation in photographic performance under various environmental conditions, good sharpness and unevenness, and is excellent as a photothermographic material for printing. You can see that

Claims (5)

In a photothermographic material having a photosensitive layer containing organic silver salt particles, silver halide particles and a reducing agent on a support and subjected to image exposure with light having a wavelength of 500 nm or less, the outermost layer on the photosensitive layer side A photothermographic material having a moisture-proof layer composed of a latex and a wax emulsion, wherein the moisture-proof layer has a glossiness of 15 to 35. ^{2. 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. 3. The photothermographic material according to claim 1, wherein the wax emulsion is paraffinic. 4. The photothermographic material according to claim 1, wherein the photosensitive layer contains a nucleating agent. 5. The photothermographic material according to claim 1, wherein the support is a low heat-shrinkable support.