JPH11295844A - Heat-developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesiveness and visual recognizability of letters and characters and the like. SOLUTION: This heat developable photosensitive material is provided with at least one photosensitive layer containing photosensitive silver halide grains and a binder on a support, and these silver halide grains have a size of 0.001-0.04 μm, and a matting agent having an average grain diameter of 1-8 μm is contained in the side same as the photosensitive layer and this photosensitive material is heat developed to form an image having a gamma value of 2-65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material (hereinafter sometimes referred to as a photothermographic material), and more particularly to a photothermographic material which is excellent in character visibility and adhesion of a developed image. It is about.

[0002]

2. Description of the Related Art Photothermographic materials have been proposed for a long time, and are described, for example, in US Pat. Nos. 3,152,904 and 345.
No. 7075 and each of B.I. "Thermal Proceed Silver System" by Shely
ssed Silver Systems) "(Imaging Processes and Mats
erials) Neblette 8th edition, edited by Sturge, V. Walworth, A. Shepp, 2nd edition
, 1996). The photothermographic material generally comprises a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and if necessary, a color tone controlling agent for controlling the color tone of silver. Having a photosensitive layer dispersed in a matrix. After the image exposure, the photothermographic material is heated to a high temperature (for example, 80 ° C. or higher), and is subjected to an oxidation-reduction reaction between silver halide or a reducible silver salt (which functions as an oxidizing agent) and the reducing agent,
A black silver image is formed. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure.
Therefore, a black silver image is formed in the exposed area.

[0003] The heat development processing has the advantage that processing liquid in the wet development processing is not required, and processing can be performed simply and quickly. However, in the field of photographic technology, an image forming method by wet development processing is still mainstream. This is because there remains an unsolved problem in the heat development processing that is not in the wet development processing.

[0004] In the photothermographic material, the content is not removed by the processing, so that the adhesion of the developed image becomes a problem. At that time, it is conceivable to use a matting agent having a large average particle size. However, in such a case, the visibility of characters such as kanji and numerals deteriorates, and no improvement measures have been found.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the visibility of characters and the adhesion of a developed image in a photothermographic material.

[0006]

This object has been achieved by the following means. (1) In a photothermographic material having at least one photosensitive layer containing photosensitive silver halide particles and a binder on a support, the size of the photosensitive silver halide particles is 0.001 μm or more and 0.04 μm or less. A photothermographic material comprising a matting agent having an average particle size of 1 to 8 μm on the same side as the photosensitive layer, and having a gamma value of 2 to 65 obtained by heat development. (2) The photothermographic material according to (1), wherein the gamma value is 10 to 50. (3) The photosensitive layer is formed by applying a coating solution in which 30% by weight or more of a solvent is water and drying, and the main binder of the photosensitive layer is an equilibrium water content of 2% by weight at 25 ° C. and 60% RH. The photothermographic material according to (1) or (2), which is a polymer described below. (4) Any one of (1) to (3), having at least two constituent layers on the support, having at least one photosensitive layer, and applying the plurality of constituent layers simultaneously. Photothermographic material. (5) The photosensitive layer according to any one of (1) to (4), wherein the photosensitive layer is a photothermographic material containing an organic silver salt, a reducing agent for silver ions, a binder, and photosensitive silver halide. Photothermographic material.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The gamma value referred to in the present invention is the density after heat development Dmin + 0.1
Energy (E1) for obtaining the density, density Dmin + 2.8
Is calculated from the gamma value = E2 / E1 by using the exposure energy (E2) for obtaining. In the present invention,
65, preferably 10 to 50.

The matting agent preferably used in the present invention is generally water-insoluble fine particles of an organic or inorganic compound. Any matting agent can be used, for example, U.S. Patent Nos. 1,939,213, 2,701,245, and 2,32
2,037, 3,262,782, 3,539,344, 3,767,
Organic matting agents described in each specification such as No. 448, 1,260,77
No. 2, 2,192,241, 3,257,206, 3,370,951
Nos. 3,523,022, 3,769,020, etc., and those well known in the art such as inorganic matting agents described in each specification can be used. For example, specifically, examples of organic compounds that can be used as a matting agent include, as examples of water-dispersible vinyl polymers, polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, acrylonitrile-α-methylstyrene copolymer, and polystyrene. ,
Styrene-divinylbenzene copolymer, polyvinyl acetate, polyethylene carbonate, polytetrafluoroethylene, etc., examples of cellulose derivatives such as methylcellulose, cellulose acetate, cellulose acetate propionate, etc., and starch derivatives such as carboxy starch and carboxynitrophenyl starch , Urea-formaldehyde-starch reactant, and the like, and gelatin hardened with a known hardener and hardened gelatin that has been coacervated and hardened into microcapsule hollow particles can be preferably used. Examples of the inorganic compound include silicon dioxide, titanium dioxide, magnesium dioxide, aluminum oxide, barium sulfate, calcium carbonate, silver chloride desensitized by a known method, silver bromide, glass, and diatomaceous earth. . The above matting agents can be used by mixing different types of substances as necessary.

In practicing the present invention, it is more preferable to use one having an average particle size of 2 μm to 6 μm. Further, the particle size distribution of the matting agent may be narrow or wide. On the other hand, since the matting agent greatly affects the haze and surface gloss of the light-sensitive material, the particle size, shape, and particle size distribution can be changed as necessary during the preparation of the matting agent or by mixing a plurality of matting agents. preferable. The particle size of the matting agent in the present invention is determined by using an electron microscope, calculating the circle-equivalent diameter from the projected area, and taking the average value as the particle diameter.

[0010] The coating amount of the matting agent, 1 to 400 mg / m ^2, more preferably from 5 to 300 mg / m ^2, in particular, it is preferable that particles greater than 4μ is 5 to 150 mg / m ^2.

The binder of the matting agent-containing layer of the present invention may be any polymer, but preferably contains a polymer having a carboxylic acid residue in an amount of from 100 mg / m ^{2 to} 5 g / m ² . Examples of the polymer having a carboxyl residue include natural polymers (such as gelatin and alginic acid), modified natural polymers (such as carboxymethylcellulose and phthalated gelatin), and synthetic polymers (polymethacrylate, polyacrylate, polyalkylmethacrylate / acrylate). Copolymer, polystyrene / polymethacrylate copolymer, etc.). The content of carboxy residues in the polymer is preferably from 1 × 10 ^-2 mol to 1.4 mol per 100 g of the polymer. Further, the carboxylic acid residue may form a salt with an alkali metal ion, an alkaline earth metal ion, an organic cation, or the like.

In the case of simultaneous aqueous multi-layer coating, which is a preferred embodiment of the present invention, gelatin is preferred from the viewpoint of preventing wind unevenness during drying, and gelatin having a high gelation speed and demineralized is particularly preferred.

As a layer containing a matting agent on the surface of the photosensitive layer, a protective layer is most suitable. The protective layer can be composed of two layers, if necessary.
By selecting an additive layer to add a regulator, a charge regulator, an ultraviolet absorber, a slip agent, a hardener, a surfactant, and the like, a design is made so that applicability, production suitability, and image quality can be compatible. be able to. The outermost protective layer preferably contains a fluorine-based surfactant together with the matting agent. Specifically, as a fluorine-based surfactant, JP-A-62-170950
No. 5,380,644, and the like, and fluorine-containing surfactants described in JP-A-60-244945, JP-A-63-188135, and the like. In the present invention, the outermost protective layer preferably contains a matting agent.

Hereinafter, the photothermographic material will be further described. The photothermographic material is preferably a mono-sheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material). The present invention
It is particularly effective in photothermographic materials for near infrared exposure.
The photothermographic material has a photosensitive layer containing photosensitive silver halide (a catalytically active amount of a photocatalyst) and a reducing agent, and a non-photosensitive layer. The photosensitive layer further contains a binder (generally a synthetic polymer) and an organic silver salt (a reducible silver source). Further, it is preferable to include a hydrazine compound (a super-high contrast agent) and a color tone adjuster (which controls the color tone of silver). A plurality of photosensitive layers may be provided. For example, for the purpose of adjusting the gradation,
A high-sensitivity photosensitive layer and a low-sensitivity photosensitive layer can be provided in the photothermographic material. The order of arrangement of the high-sensitivity photosensitive layer and the low-sensitivity photosensitive layer may be such that the low-sensitivity photosensitive layer is disposed below (the support side) or the high-sensitivity photosensitive layer is disposed below. The non-photosensitive layer may be provided as another functional layer such as a surface protective layer, in addition to a dye-containing layer described later, that is, a filter layer and an antihalation layer.

As a support of the photothermographic material, paper, polyethylene-coated paper, polypropylene-coated paper, parchment, cloth, metal (eg, aluminum, copper, magnesium, zinc) sheet or thin film, glass, Glass and plastic films coated with a metal (eg, chromium alloy, steel, silver, gold, platinum) are used. Examples of the plastic used for the support include polyalkyl methacrylate (eg, polymethyl methacrylate), polyester (eg, polyethylene terephthalate), polyvinyl acetal, polyamide (eg, nylon), and cellulose ester (eg, cellulose nitrate, cellulose). Acetate, cellulose acetate propionate, cellulose acetate butyrate). The support may be coated with a polymer. Examples of polymers include polyvinylidene chloride, acrylic acid based polymers (eg,
Polyacrylonitrile, methyl acrylate), polymers of unsaturated dicarboxylic acids (eg, itaconic acid, acrylic acid), carboxymethylcellulose and polyacrylamide. Copolymers may be used. Instead of coating with a polymer, an undercoat layer containing a polymer may be provided.

As silver halide, any of silver bromide, silver iodide, silver chloride, silver chlorobromide, silver iodobromide and silver chloroiodobromide can be used. The distribution of the halogen composition in the grains may be uniform, the halogen composition may change stepwise, or may change continuously. Further, silver halide grains having a core / shell structure can be preferably used. The preferred structure is a two- to five-layer structure, and more preferably, a core / shell particle having a two- to four-layer structure can be used. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used. The grain size of the silver halide grains is 0.001 μm or more and 0.04
μm or less, preferably 0.005 μm or more and 0.0
4 μm or less. The grain size of the silver halide grains in the present invention is determined by using an electron microscope, calculating the circle equivalent diameter from the projected area, and averaging the values.

Methods for forming photosensitive silver halide are well known in the art, for example, Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,45.
The method described in No. 8 can be used. Specifically, silver halide is prepared as a silver halide emulsion by reacting silver nitrate with a soluble halide salt. In addition,
It may be prepared by reacting silver soap with halogen ions and converting the soap portion of silver soap into halogen. Further, halogen ions may be added during the formation of the silver soap.

As the reducing agent preferably used in the present invention, phenidone, hydroquinones, catechol and hindered phenol are preferable. As for the reducing agent, US Pat. Nos. 3,770,448 and 3,773,512;
Nos. 3,593,863 and 4,460,681,
And Research Discl
osure) magazines 17029 and 29963.

Examples of the reducing agent include aminohydroxycycloalkenone compounds (eg, 2-hydroxy-piperidino-
2-cyclohexenone), N-hydroxyurea derivatives (eg, Np-methylphenyl-N-hydroxyurea), hydrazones of aldehydes or ketones (eg, anthracenaldehyde phenylhydrazone), phosphoramidophenols, phosphates Amidoanilines,
Polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone, 2,
5-dihydroxy-phenylmethylsulfone), sulfohydroxamic acids (eg, benzenesulfohydroxamic 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), amidooxines, azines (eg, aryl aryl carboxylate) Hydrazides) and ascorbic acid, polyhydroxybenzene and hydroxylamine, reductone, hydrazine, hydroxamic acids, azines and sulfonamidephenols, α-cyanophenylacetic acid derivatives, bis-β- Naphtho , A combination of a 1,3-dihydroxybenzene derivative, 5-pyrazolones, sulfonamidophenols, and 2-phenylindane-1,3-
Dione, chroman, 1,4-dihydropyridines (eg,
2,6-dimethoxy-3,5-dicarbethoxy-1,
4-dihydropyridine), bisphenols (eg, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy -3-methylphenyl) propane, 4,4-ethylidene-bis (2-t-
Butyl-6-methyl) phenol), UV-sensitive ascorbic acid derivatives and 3-pyrazolidones.

An ester of an aminoreductone (eg, piperidinohexose reductone monoacetate) which functions as a precursor of the reducing agent may be used as the reducing agent. Particularly preferred reducing agents are hindered phenols. The addition amount of the reducing agent is preferably from 0.01~5.0g / m ^2, and more preferably 0.1 to 3.0 g / m ^2.

The photosensitive layer and the non-photosensitive layer preferably contain a binder. Generally, a colorless transparent or translucent polymer is used as the binder.

The effect of the present invention is that the photosensitive layer contains 30% by weight of the solvent.
When the composition is formed by coating and drying using a coating solution containing water as described above, the main binder of the photosensitive layer (70% by weight or more, preferably 80% by weight or more of all binders in the photosensitive layer) further contains an aqueous solvent ( (Water solvent), which can be dissolved or dispersed, especially when the polymer latex has an equilibrium water content at 25 ° C. and 60% RH of 2 wt% or less. The most preferred form is
It is prepared so as to have an ionic conductivity of 2.5 mS / cm or less. As such a preparation method, a method of purifying using a separation functional membrane after polymer synthesis can be mentioned.

The main binder of the present invention referred to herein (hereinafter referred to as the main binder)
The aqueous solvent in which the polymer of the present invention is soluble or dispersible is water or a mixture of water and 70 wt% or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethyl acetate; and dimethylformamide. Note that the term “aqueous solvent” is used herein even in a system in which the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The “equilibrium water content at 25 ° C. and 60% RH” referred to in the present invention refers to the weight W1 of the polymer that is in a moisture-conditioning equilibrium in an atmosphere of 25 ° C. and 60% RH, and the weight of the polymer that is in an absolutely dry state at 25 ° C. weight
It can be expressed as follows using W0.

Equilibrium water content at 25 ° C. and 60% RH = [(W1-W
0) / W0) × 100 (wt%)

The definition and measurement method of the water content are described in, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by the Society of Polymer Science,
Citizen Library). The equilibrium water content of the polymer of the present invention at 25 ° C. and 60% RH is preferably 2% by weight or less, more preferably 0.01% by weight or more and 1.5% by weight or less, further preferably 0.02% by weight or more and 1% by weight or less. The polymer of the present invention is not particularly limited as long as it is soluble or dispersible in the above-mentioned aqueous solvent and has an equilibrium water content of 2% by weight or less at 25 ° C. and 60% RH. Among these polymers, polymers that can be dispersed in an aqueous solvent are particularly preferred.

Examples of the dispersion state include a latex in which fine particles of a solid polymer are dispersed, and a dispersion state in which polymer molecules are dispersed in a molecular state or in the form of micelles.

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

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

Specific examples of preferred polymers include the following. In the following, the raw material monomers are used, the numerical value in parentheses is wt%, and the molecular weight is the number average molecular weight. P-1; -MMA (70) -EA (27) -MAA (3)-latex (molecular weight 37
000) P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-latex (molecular weight 40000) P-3; -St (50) -Bu (47) -MAA ( 3) -Latex (molecular weight 4500
0) Latex of P-4; -St (68) -Bu (29) -AA (3)-(molecular weight 6000
0) Latex of P-5; -St (70) -Bu (27) -IA (3)-(molecular weight 1200
00) Latex of P-6; -St (75) -Bu (24) -AA (1)-(molecular weight 1080
00) Latex of P-7; -St (60) -Bu (35) -DVB (3) -MAA (2)-(molecular weight 150,000) P-8; -St (70) -Bu (25) -DVB ( 2) -AA (3)-latex (molecular weight 280,000) P-9; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (molecular weight 80000) P-10; -VDC (85) -MMA (5) -EA (5) -MMA (5)-latex (molecular weight 67,000) P-11; -Et (90) -MAA (10)-latex (molecular weight) 12000)

The abbreviations of the above structures represent the following monomers.
MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, VC; vinyl chloride, AN;
Acrylonitrile, VDC; vinylidene chloride, Et; ethylene, IA; itaconic acid.

The polymers described above are commercially available, and the following polymers can be used. Examples of the acrylic resin include Sebian A-4635,46583,4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821,
Examples of polyester resins such as 820, 857 (all manufactured by Zeon Corporation) include FINETEX ES650, 611, 675, 85
HYDRAN AP10, 20, 30, 40 (Dai Nippon Ink Chemical Co., Ltd.) is an example of polyurethane resin such as 0 (Dai Nippon Ink Chemical Co., Ltd.), WD-size, WMS (Eastman Chemical). For example, LA-based resin
CSTAR 7310K, 3307B, 4700H, 7132C (all manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx416, 410, 438C, 2507
Examples of vinyl chloride resins include G351 and G576 (manufactured by Nippon Zeon). Examples of vinylidene chloride resins include L502 and L513 (manufactured by Asahi Kasei Corporation). Examples of olefin resins include Chemipearl S120 and SA100 (Mitsui Petrochemical Co., Ltd.)
Manufactured). These polymers may be used alone as a polymer latex, or two or more may be blended if necessary.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 40:60 to 95: 5. The proportion of the styrene monomer unit and butadiene monomer unit in the copolymer is preferably 60 to 99% by weight. The preferred molecular weight range is the same as described above.
Examples of the styrene-butadiene copolymer latex preferably used in the present invention include the above-mentioned P-3 to P-8, and commercially available products such as LACSTAR-3307B, 7132C, and Nipol Lx416.

The photosensitive layer of the light-sensitive material of the present invention may optionally contain a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose and the like. The addition amount of these hydrophilic polymers is preferably 30% by weight or less, more preferably 20% by weight or less of the total binder in the photosensitive layer. The photosensitive layer of the present invention is preferably formed using a polymer latex,
As for the amount of the binder in the photosensitive layer, the weight ratio of the total binder / organic silver salt is preferably in the range of 1/1 to 10/1, more preferably 1/5 to 4/1. The weight ratio of total binder / silver halide is 40.
The range is preferably from 0 to 5, more preferably from 200 to 10.

The total amount of binder in the photosensitive layer of the present invention is 0.2
To 30 g / m ^2, more preferably in the range of 1 to 15 g / m ^2. The photosensitive layer of the present invention may contain a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like.

In the present invention, the solvent of the coating solution for the photosensitive layer of the photosensitive material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is an aqueous solvent containing 30% by weight or more of water.
As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent in the coating liquid is preferably at least 50 wt%, more preferably at least 70 wt%. Examples of preferred solvent compositions include water / methyl alcohol = 90/10, water / methyl alcohol = 70/30,
Water / methyl alcohol / dimethylformamide = 80/15 /
5, water / methyl alcohol / ethyl cellosolve = 85/10 /
5, water / methyl alcohol / isopropyl alcohol = 8
5/10/5 and so on.

The photosensitive layer or the non-photosensitive layer preferably further contains a non-photosensitive organic silver salt. The organic acid forming the silver salt is preferably a long-chain fatty acid. The fatty acid preferably has 10 to 30 carbon atoms, and has 15 to 2 carbon atoms.
More preferably, it is 5. An organic silver salt complex may be used. The ligand of the complex preferably has a total stability constant for silver ions in the range of 4.0 to 10.0.
Organic silver salts are described in Research Disclosure Magazine Nos. 17029 and 299.
No. 63.

Examples of organic silver salts include silver salts of fatty acids (eg, gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid), carboxyalkylthioureas (eg, 1- (3-carboxypropyl) ) Thiourea, 1-
Silver salt of (3-carboxypropyl) -3,3-dimethylthiourea), silver complex of polymer reaction product of aldehyde (eg, formaldehyde, acetaldehyde, butyraldehyde) and hydroxy-substituted aromatic carboxylic acid, aromatic carboxylic acid Silver salts of (e.g., salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid), thioenes (e.g., 3- (2-carboxyethyl)-
Silver salt or silver complex of 4-hydroxymethyl-4-thiazoline-2-thioene, 3-carboxymethyl-4-thiazoline-2-thioene), nitrogen acid (eg, imidazole, pyrazole, urazole, 1,2,4- Thiazole, 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole, benzotriazole)
Or silver complexes of saccharin, silver salts of 5-chlorosalicylaldoxime and silver salts of mercaptides. Silver behenate is most preferred. Organic silver salts
Is preferably used in 0.05 g / m ² or more 3 g / m ² or less as the amount of silver, and more preferably used in 0.3 g / m ² or more 2 g / m ² or less.

The photosensitive layer or the non-photosensitive layer preferably further contains a super-high contrast agent. When a photothermographic material is used in the field of photographic printing, it is important to reproduce a continuous tone image or a line image using halftone dots. By using a super-high contrast agent, the reproducibility of halftone images and line images can be improved. As the super-high contrast agent, a hydrazine compound, a quaternary ammonium compound or an acrylonitrile compound (described in US Pat. No. 5,545,515) is used. Hydrazine compounds are particularly preferred ultrahigh contrast agents. Hydrazine compounds include compounds hydrazine (H ₂ N-NH ₂₎ and less of the hydrogen atom was replaced one. As the substituent, an aliphatic group, an aromatic group or a heterocyclic group is directly bonded to a hydrazine nitrogen atom, or an aliphatic group, an aromatic group or a heterocyclic group is bonded to a hydrazine nitrogen atom via a linking group. . Examples of the linking group include -CO-, -CS-, -S
O ₂ -, - POR- (R is an aliphatic group, an aromatic group or a heterocyclic group), - it includes CNH- and combinations thereof. For hydrazine compounds, see US Pat.
738, 5496695, 5512411,
Nos. 5,536,622, JP-B-6-77138
No. 6-93082, JP-A-6-230497,
6-289520, 6-313951, 7-
No. 5610, No. 7-77783, No. 7-104426
There is a description in each gazette of the issue.

The hydrazine compound can be dissolved in an appropriate organic solvent and added to the coating solution for the photosensitive layer. Examples of organic solvents include alcohols (eg, methanol, ethanol, propanol, fluorinated alcohols), ketones (eg, acetone, methyl ethyl ketone), dimethylformamide, dimethyl sulfoxide, and methyl cellosolve. In addition, hydrazine compound is oily (auxiliary)
A solution dissolved in a solvent may be emulsified in a coating solution. Examples of oily (auxiliary) solvents include dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate, ethyl acetate and cyclohexanone. Further, a solid dispersion of a hydrazine compound may be added to the coating solution. The dispersion of the hydrazine compound is
It can be carried out using a known dispersing machine such as a ball mill, a colloid mill, a Menton-Gauling, a microfluidizer and an ultrasonic dispersing machine. The added amount of the super-high contrast agent is preferably 1 × 10 ^{-6 to} 1 × 10 ^-2 mol, and more preferably 1 × 10 ^{-5 to} 5 × 10 ^-3 mol, per mol of silver halide. More preferably, 2 × 10 ^{-5 to} 5 × 10
Most preferably, it is ^-3 mol. In addition to the super-high contrast agent, a high-contrast accelerator may be used. Examples of the high contrast accelerator include amine compounds (described in US Pat. No. 5,545,505), hydroxamic acids (described in US Pat. No. 5,545,507), and acrylonitriles (US Pat. No. 5,554,550).
No. 7) and a hydrazine compound (US Pat.
No. 558983). The photosensitive layer or the non-photosensitive layer preferably further contains a color tone adjuster. The color tone adjuster is described in Research Disclosure No. 17029.

Examples of color tone adjusting agents include imides (eg, phthalimide), cyclic imides (eg, succinimide), pyrazolin-5-ones (eg, 3-phenyl-2-pyrazolin-5-one, -Phenylurazole), quinazolinones (eg, quinazoline, 2,4-thiazolidinedione), naphthalimides (eg, N-hydroxy-1,
8-naphthalimide), a cobalt complex (eg, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3-mercapto-1,2,4-triazole), N- (aminomethyl) aryldicarboximides (eg, N- (dimethylaminomethyl) phthalimide), blocked pyrazoles (eg, N, N′hexamethylene-1-carbamoyl-3,5-dimethylpyrazole), isothiuronium derivatives (eg, 1,8- ( A combination of 3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and a photobleach (eg, 2- (tribromomethylsulfonyl) benzothiazole), a merocyanine dye (eg, 3-
Ethyl-5-((3-ethyl-2-benzothiazolinylidene) -1-methylethylidene) -2-thio-2,4-oxazolidinedione (oxaz
olazinedione)), phthalazinone compounds and metal salts thereof (eg, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, 2,3-dihydro-1,4- Phthalazinedione, 8-methylphthalazino), a combination of a phthalazinone compound and a sulfinic acid derivative (eg, sodium benzenesulfinate), a phthalazinone compound and a sulfonic acid derivative (eg, sodium p-toluenesulfonate)
Phthalazine and its derivatives (eg, phthalazine, 6-isopropylphthalazine, 6-methylphthalazine), phthalazines and phthalic acid, phthalazine or furalazine adduct and dicarboxylic acid (preferably o-phenylene acid) ) Or anhydrides thereof (eg, maleic anhydride, phthalic acid, 2,3-naphthalenedicarboxylic acid, phthalic anhydride, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride); Quinazolinediones, benzoxazine, naloxazine derivatives, benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione),
Pyrimidines, asymmetric triazines (for example, 2,4-
Dihydroxypyrimidine), tetraazapentalene derivatives (eg, 3,6-dimerocapto-1,4-diphenyl-
1H, 4H-2, 3a, 5, 6a-tetraazapentalene). Phthalazines are particularly preferred. The toning agent is preferably contained in the image forming layer surface in an amount of from 0.1 to 50 mol% per mol of silver, more preferably from 0.5 to 20 mol%.

An antifoggant may be added to the photosensitive layer or the non-photosensitive layer (preferably the photosensitive layer). As an antifoggant, a mercury compound (described in US Pat. No. 3,589,903) is more preferable than a non-mercury compound (US Pat.
No. 946, No. 4546075, No. 44452885,
Nos. 4,756,999 and 5,028,523, UK Patent Application Nos. 92221383.4 and 93001777.7.
Nos. 9311790.1 and JP-A-59-1790.1.
57234). Particularly preferred antifoggants include halogens (F, Cl, Br,
I) A heterocyclic compound having a substituted methyl group.

Silver halide is generally used after spectral sensitization. Regarding spectral sensitizing dyes, see JP-A-60-1403.
No. 35, No. 63-159,841 and No. 63-23143
No. 7, 63-259,651 and 63-304242
Nos. 63-15245 and U.S. Pat.
Nos. 414, 474,455 and 474,966,
Nos. 4,751,175 and 4,835,096. In the photothermographic material, a surfactant,
Antioxidants, stabilizers, plasticizers, ultraviolet absorbers or coating aids may be added. Various additives are added to either the photosensitive layer or the non-photosensitive layer.

In the present invention, it is preferable to add a decoloring dye and a base precursor to the non-photosensitive layer of the photothermographic material so that the non-photosensitive layer functions as a filter layer or an antihalation layer. A photothermographic material generally has a non-photosensitive layer in addition to a photosensitive layer. The non-photosensitive layer is composed of (1) a protective layer provided on the photosensitive layer (on the side farther from the support), (2) an intermediate layer provided between a plurality of photosensitive layers, and (3) It can be classified into an undercoat layer provided between the photosensitive layer and the support, and (4) a back layer provided on the opposite side of the photosensitive layer. The filter layer is provided on the photosensitive material as the layer (1) or (2). The antihalation layer is provided on the photosensitive material as the layer (3) or (4). The decolorizable dye and the base precursor are preferably added to the same non-photosensitive layer. However, they may be separately added to two adjacent non-photosensitive layers. Further, a barrier layer may be provided between the two non-photosensitive layers. In the present specification, `` the layer contains a decolorizing dye and a base precursor '' means that the `` layer '' is plural, that is, the case where a plurality of layers are adjacent layers that separately contain the decolorizing dye and the base precursor. included.

As a method of adding the decolorizable dye to the non-photosensitive layer, a method of adding a solution, an emulsion, a solid fine particle dispersion or a polymer impregnated substance to the coating solution of the non-photosensitive layer can be adopted. Further, a dye may be added to the non-photosensitive layer using a polymer mordant. These addition methods are the same as the method of adding a dye to an ordinary photothermographic material. Latex used in polymer impregnation is disclosed in US Pat.
9363, West German Patent Publication No. 25141274, 25
No. 41230, European Patent Publication 029104, and JP-B-53-41091. Further, the emulsification method of adding a dye to a solution in which a polymer is dissolved is described in International Publication No. 88/00723.

The amount of the decolorizable dye is determined depending on the use of the dye. Generally, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably from 0.2 to 2. The amount of the dye used to obtain such an optical density is generally 0.0
It is about 01 to 1 g / m ² . Preferably, 0.005
To about 0.8 g / m ² , and particularly preferably 0.0
It is about 1 to 0.2 g / m ² .

When the dye is decolorized according to the present invention, the optical density can be reduced to 0.1 or less. Two or more decolorizable dyes may be used in combination in a heat-decolorable recording material or a photothermographic material. Similarly, two or more base precursors may be used in combination.

The photothermographic material forms an image by heating after image exposure. By this heat development, a black silver image is formed. The image exposure is preferably performed using a laser. The heating temperature for thermal development is 80 to 25.
The temperature is preferably 0 ° C, more preferably 100 to 200 ° C. The heating time is generally between 1 second and 2 minutes.

As a method of thermal development, a plate heater method is preferable. The heat development method using a plate heater method is a method described in Japanese Patent Application No. 9-229684, in which a heat development photosensitive material having a latent image formed thereon is brought into contact with a heating means in a heat development section to obtain a visible image. A developing device,
The heating means comprises a plate heater, and a plurality of pressing rollers are disposed facing each other along one surface of the plate heater, and the photothermographic material is passed between the pressing roller and the plate heater. A thermal developing device for performing thermal development.

As a heating method in the heat development processing, for example, the forms shown in FIGS. The photothermographic material conveyed to the image exposing unit is exposed to laser light or the like scanned by a light beam, and a latent image is formed on the photothermographic material. You. At this time, dust on the back and front surfaces of the photothermographic material is removed by the dust removing roller.

As shown in FIG. 1, the heat developing section 18
Is a portion in which a latent image is made visible by heating the photothermographic material A by heating, and in the present invention, the plate heater 120 and the plate heater 120 It is characterized by having a plurality of pressing rollers 122 arranged facing each other. The plate heater 120 is a plate-like heating member in which a heating element such as a nichrome wire is laid and accommodated in a plane, and is maintained at the developing temperature of the photothermographic material A. Further, the surface of the plate heater 120 is coated with a fluororesin for the purpose of reducing the frictional resistance or imparting abrasion resistance,
It is preferable to stick a sheet made of a fluororesin.

Further, in the photothermographic material A, the volatile components evaporate by heating during the thermal development, and the photothermographic material A floats up from the plate heater 120 with the heating, and the contact between the photothermographic material A and the plate heater 120 is reduced. May be uniform. Therefore, it is preferable to form minute irregularities on the surface of the plate heater 120 in order to release the vapor. In addition, in order to compensate for a temperature decrease due to heat radiation at both ends of the plate heater 120, it is preferable to provide a temperature gradient so that the temperature at both ends is higher than the other portions.

The pressing roller 122 is a plate heater 12
0, or at a predetermined pitch over the entire length of the plate heater 120 in the transport direction with an interval equal to or less than the thickness of the photothermographic material A, and the pressing roller 122 and the plate heater 120 generate heat. A developing photosensitive material conveying path is formed. By arranging the photothermographic material conveying path at an interval equal to or less than the thickness of the photothermographic material A, buckling of the photothermographic material A can be prevented. A supply roller pair 126 and a discharge roller pair 128 are provided at both ends of the photothermographic material conveying path 124. Further, it is preferable to dispose a heat retaining cover 125 for retaining heat on the side of the pressing roller 122 opposite to the plate heater 120.

When the front end of the photothermographic material A comes into contact with the pressing roller 122 while the photothermographic material A is being conveyed, the photothermographic material A stops momentarily. At this time, when the pressing rollers 122 are separated from each other at an equal pitch, the same portion of the photothermographic material A
It stops every two times, and that portion is pressed against the plate heater 120 for a long time, and as a result, the photothermographic material A has streak-like development unevenness extending in the width direction. Therefore, it is preferable to make the pitch of each pressing roller 122 non-uniform.

Further, as shown in FIG.
A configuration is also possible in which a driving roller 130 having the envelope surface of the peripheral surface 22 as a peripheral surface is provided in contact with each of the pressing rollers 122, and each of the pressing rollers 122 is rotated by rotating the driving roller 130. In the above description, the plate heater 120 includes a plate member made of a heat conductor, and a configuration in which a heat source is arranged on the side of the plate member opposite to the heating surface of the photothermographic material A.

[0056]

The present invention will be specifically described below with reference to examples. Example 1 (Preparation of Silver Halide Emulsion 1) To a stainless steel reaction bottle, a solution obtained by adding 8 cc of a 1 wt% potassium bromide solution to 1421 cc of distilled water, further adding 8.2 cc of 1N nitric acid and 20 g of phthalated gelatin was added. While maintaining the solution temperature at 37 ° C., a solution A prepared by adding distilled water to 37.04 g of silver nitrate to 159 cc and a solution B prepared by diluting 32.6 g of potassium bromide to a volume of 200 cc with distilled water were prepared. The entire amount of solution A was added at a constant flow rate over one minute while maintaining the pAg at 8.1 by the control double jet method. (Solution B was added by a controlled double jet method.) Thereafter, 30 cc of a 3.5% aqueous hydrogen peroxide solution was added, and 36 cc of a 3 wt% aqueous solution of compound 1 was added. After that, the solution A is again diluted with distilled water.
Compound 2 was dissolved in 317.5 cc of solution A2 and solution B so that the final concentration was 1 × 10 ^-4 mole per mole of silver in solution B, and the solution was diluted with distilled water to 400 cc, twice that of solution B. Using the solution B2, a controlled double jet method was also used to maintain the pAg at 8.1 while maintaining the solution A at a constant flow rate.
2 was added over 10 minutes. (Solution B2 was added by a controlled double jet method.)
Add 50cc of 0.5% methanol solution, and further pAg with silver nitrate
Was reduced to 7.5, the pH was adjusted to 3.8 with 1N sulfuric acid, stirring was stopped, sedimentation / desalting / washing steps were performed, 3.5 g of deionized gelatin was added, and 1N sodium hydroxide was added. , PH 6.0 and pAg 8.2 to prepare a silver halide dispersion.

The grains in the completed silver halide emulsion had an average equivalent circle diameter of 0.053 μm and a coefficient of variation of the equivalent spherical diameter of 18%.
Was pure silver bromide particles. The particle size and the like were determined from the average of 1000 particles using an electron microscope. [10
0] The surface ratio was determined to be 85% using the Kubelka-Munk method. The temperature of the emulsion was raised to 50 ° C. with stirring to give Compound 4
5 cc of a 0.5 wt% solution of the above and 5 cc of a 3.5 wt% solution of the compound 5 were added, and one minute later, the compound 6 was added at 3 × 10 ⁻⁵ mol per mol of silver. After a further 2 minutes, 5 × 10 ^-3 mol of a solid dispersion of the spectral sensitizing dye A (aqueous gelatin solution) was added per mol of silver,
After another 2 minutes, tellurium sensitizer B was added at 5 × 10 ^-5 per mole of silver.
Mol was added and the mixture was aged for 50 minutes. Immediately before the end of ripening, compound 3
Was added at 1 × 10 ⁻³ mol per mol of silver to lower the temperature, and the chemical sensitization was terminated to prepare a silver halide emulsion 1. Emulsion having an average equivalent circle diameter of 0.038 μm and 0.025 μm was prepared in the same manner as in Emulsion 1, except that the flow rate of solution A was adjusted.

(Preparation of Silver Organic Acid Dispersion) 43.8 g of behenic acid (product name: Edenor C22-85R) manufactured by Henkel, 730 ml of distilled water
, 60 ml of tert-butanol was stirred at 79 ° C while 1N-NaOH
117 ml of an aqueous solution was added over 55 minutes and reacted for 240 minutes.
Then, 112.5 ml of an aqueous solution of 19.2 g of silver nitrate was added over 45 seconds, left as it was for 20 minutes, and cooled to 30 ° C. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the conductivity of the filtrate became 30 μS / cm. The solid content thus obtained is treated as a wet cake without drying,
To a wet cake having a dry solid content of 100 g, 7.4 g of polyvinyl alcohol (trade name: PVA-205) and water were added to make a total amount of 385 g, and the mixture was predispersed with a homomixer. Next, the pre-dispersed undiluted solution is dispersed in a disperser (trade name:
The pressure of a microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using a G10Z interaction chamber) was adjusted to 1750 kg / m ² , and the mixture was treated three times to obtain a silver behenate dispersion B. The silver behenate particles contained in the silver behenate dispersion thus obtained have an average minor axis of 0.04 μm and an average major axis of 0.
Needle-like particles having a size of 8 μm and a coefficient of variation of 30%. The measurement of the particle size was performed by MasterSizerX manufactured by Malvern Instruments Ltd. In the cooling operation, a coiled heat exchanger was mounted before and after the interaction chamber, and the temperature of the refrigerant was adjusted to a desired dispersion temperature.

(Preparation of 25% dispersion of reducing agent) 1,1-bis (2
-80 g of (hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and modified POVAL MP203 manufactured by Kuraray Co., Ltd.
176 g of water was added to 64 g of a 20% aqueous solution and mixed well to form a slurry. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put in a vessel together with the slurry, and use a dispersing machine (1 / 4G sand grinder mill: manufactured by Imex Co., Ltd.)
The mixture was dispersed for a time to obtain a reducing agent dispersion. The reducing agent particles contained in the thus obtained reducing agent dispersion had an average particle size of 0.72 μm.

(Preparation of 20% Dispersion of Mercapto Compound)
3-mercapto-4-phenyl-5-heptyl-1,2,4-triazole 64g and 20% of modified Poval MP203 manufactured by Kuraray Co., Ltd.
224 g of water was added to 32 g of the aqueous solution and mixed well to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm were prepared, put into a vessel together with the slurry, and dispersed with a disperser (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 10 hours to obtain a mercapto dispersion. The mercapto compound particles contained in the thus obtained mercapto compound dispersion had an average particle size of 0.67 μm.

(Preparation of 30% dispersion of organic polyhalogen compound) 48 g of tribromomethylphenylsulfone and 3-tribromomethylsulfonyl-4-phenyl-5-tridecyl-1,
48 g of 2,4-triazole and modified Poval M manufactured by Kuraray Co., Ltd.
224 g of water was added to 48 g of a 20% aqueous solution of P203 and mixed well to form a slurry. Zirconia beads 80 with an average diameter of 0.5 mm
Prepare 0 g, put it in a vessel together with the slurry, and use a dispersing machine (1/4 G sand grinder mill: IMEX Co., Ltd.)
For 5 hours to obtain an organic polyhalogen compound dispersion. The polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had an average particle size of 0.74 μm.

(Preparation of 10% methanol solution of phthalazine compound) 10 g of 6-isopropylphthalazine was dissolved in 90 g of methanol and used.

(Preparation of 20% Dispersion of Pigment) CI Pigment
Water 25 to 64 g of Blue 60 and 6.4 g of Demol N manufactured by Kao Corporation
0 g was added and mixed well to obtain a slurry. Average diameter 0.5
800 g of zirconia beads having a diameter of 0.8 mm was prepared, put into a vessel together with the slurry, and dispersed with a dispersing machine (1/4 G sand grinder mill: manufactured by Imex Co., Ltd.) for 25 hours to obtain a pigment dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

(SBR latex 40wt%) ultrafiltration (UF)
Purified SBR latex was obtained as follows. SB below
R latex diluted 10 times with distilled water was diluted and purified using a UF-purification module, FS03-FC-FUY03A1 (Daisen Membrane System Co., Ltd.) until the ionic conductivity reached 1.5 mS / cm. At this time, the latex concentration was 40% (SBR latex: -St (68) -Bu (29) -AA (3)-latex) The equilibrium water content was 0.7%, and the average particle size was 0.1. μm, concentration 45%, ionic conductivity 4.2mS / cm (Ion conductivity was measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd.
%) At 25 ° C), pH 8.2

(Preparation of Coating Solution for Emulsion Layer)
1.1 g of a 20% dispersion, 103 g of an organic acid silver dispersion, 5 g of a 20 wt% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.),
The above 25% reducing agent dispersion (the amount of addition was adjusted to adjust the gamma value), 30% organic polyhalogen compound dispersion
11.5 g, mercapto compound 20% dispersion 3.1 g, UF purified
106g of SBR latex 40wt%, 20% of phthalazine compound
8 ml of the resulting solution was added, and 10 g of silver halide grains were mixed well to prepare an emulsion layer coating solution, which was coated so as to be 70 ml / m ² .

The viscosity of the coating solution for the emulsion layer was 85 mPa · s at 40 ° C. as measured with a B-type viscometer of Tokyo Keiki. The viscosity of the coating solution at 25 ° C. using an RFS Fluid Spectrometer manufactured by Rheometrics Far East Co., Ltd. was 1,500, 220, 70, 40 at a shear rate of 0.1, 1, 10, 100, and 1000 [1 / sec]. It was 20 [mPa · s].

(Preparation of Emulsion Surface Intermediate Layer Coating Solution) A 10 wt% aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.)
2g, methyl methacrylate / styrene / 2-ethylhexyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 59/9/26/5/1) 27.5% latex 226g aerosol OT (American cyanamide) 2 ml) of a 5 wt% aqueous solution (produced by K.K.) was used as a coating solution for the intermediate layer, and applied so as to be 5 ml / m ² . The viscosity of the coating solution was 21 [mPa · s] at 40 ° C. with a B-type viscometer.

(Preparation of Coating Solution for First Layer of Emulsion Surface Protecting Layer) Inert gelatin (80 g) was dissolved in water, 64 ml of a 10% methanol solution of phthalic acid, 74 ml of a 10% aqueous solution of 4-methylphthalic acid,
28 ml of 1N sulfuric acid and 5 ml of a 5 wt% aqueous solution of aerosol OT (manufactured by American Cyanamid Co.) were added, and water was added to make a total amount of 1000 g to prepare a coating solution for the first layer of the emulsion surface protective layer.
It was applied so as to be ml / m ² . The viscosity of the coating solution was 17 mPa · s at 40 ° C. with a B-type viscometer.

(Preparation of Coating Solution for Second Layer of Emulsion Surface Protective Layer) Inert gelatin (100 g) was dissolved in water, and N-perfluorooctylsulfonyl-N-propylalanine potassium salt 5%
20 ml of the solution, 16 ml of a 5 wt% solution of Aerosol OT (manufactured by American Cyanamid Co.), 25 g of polymethyl methacrylate fine particles (average particle size 4.0 μm), 1.4 g of phthalic acid, 1.6 g of 4-methylphthalic acid, 1N 44 ml of sulfuric acid and 445 ml of 4 wt% chrome alum were added, and water was added to make a total amount of 2000 g to prepare a coating liquid for the second layer of the emulsion surface protective layer, which was coated to a concentration of 10 ml / m ² . The viscosity of the coating solution is 9 at 40 ° C with a B-type viscometer.
[MPa · s].

(Preparation of PET support) Intrinsic viscosity IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (weight ratio)) using terephthalic acid and ethylene glycol according to a conventional method. Of PET. After pelletizing this at 130 ° C
After drying for 4 hours, it was melted at 300 ° C, extruded from a T-die, and quenched to prepare an unstretched film with a thickness of 175 µm after heat setting.

This was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then transversely stretched 4.5 times using a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. After that, it was heat-set at 240 ° C. for 20 seconds and relaxed 4% in the transverse direction at the same temperature. After slitting the chuck portion of the tenter, knurling was performed on both ends, and the roll was wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

(Surface Corona Treatment) Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was treated at 0.375 kV · A · minute / m ² . At this time, the processing frequency was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

(Preparation of Undercoating Support) (Preparation of Undercoating Coating Solution A) Polystyrene fine particles (average particle size: 0.2 μm) were added to 200 ml of a polyester copolymer aqueous dispersion Pesresin A-515GB (30%, manufactured by Takamatsu Yushi Co., Ltd.). ) 1g, surfactant
20 ml of 1 (1 wt%) was added, and distilled water was added thereto to make 1000 ml, thereby obtaining an undercoat coating solution A.

(Preparation of Undercoating Coating Solution B) Styrene-butadiene copolymer aqueous dispersion (styrene / butadiene / itaconic acid = 47/50/3 (weight ratio), concentration: 30 wt%) in 680 ml of distilled water
100 ml, 1.1 g of polystyrene fine particles (average particle size 0.4 μm), and distilled water to make 1000 ml.
B

(Preparation of Undercoating Coating Solution C) Inert gelatin (10 g) was dissolved in distilled water (500 ml).
40 g of an aqueous dispersion (40 wt%) of tin oxide-antimony oxide composite fine particles described in the specification of JP-A No. 3 was added, and distilled water was added thereto to make 1000 ml, thereby obtaining an undercoating coating solution C.

(Preparation of undercoat support) The above thickness of 175 μm
After applying the above-mentioned corona discharge treatment to one surface (photosensitive surface) of the biaxially stretched polyethylene terephthalate support, the undercoating coating solution A was applied with a bar coater so that the wet coating amount was 5 ml / m ² , and then 180 ° C. For 5 minutes. Dry film thickness is about
0.3 μm. Next, after applying a corona discharge treatment to the back surface (back surface), the undercoat coating solution B was applied using a bar coater so that the wet coating amount was 5 ml / m ² and the dry film thickness was about 0.3 μm. After drying for 5 minutes, the undercoating solution C was further coated on the bar with a bar coater to a wet coating amount of 3 ml /
m ² , the coating was dried so as to have a dry film thickness of about 0.03 μm, and dried at 180 ° C. for 5 minutes to prepare an undercoat support.

(Preparation of Back Surface Coating Solution) (Preparation of Solid Precursor Dispersion (a) of Base Precursor) 64 g of base precursor compound (11), 28 g of diphenylsulfone compound (12) and surfactant Demol manufactured by Kao Corporation
10 g of N was mixed with 220 ml of distilled water, and the mixture was dispersed in beads using a sand mill (1/4 Gallon sand grinder mill, manufactured by Imex Co., Ltd.), and the average particle size was 0.2 μm.
To obtain a solid fine particle co-dispersion liquid of a base precursor compound and a diphenylsulfone compound.

(Preparation of Dye Solid Fine Particle Dispersion) 9.6 g of cyanine dye compound (13) and 5.8 g of sodium p-alkylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixture was subjected to a sand mill (1/4 Gallon sand grinder mill, The beads were dispersed by using IMEX Co., Ltd.) to obtain a dye solid fine particle dispersion having an average particle diameter of 0.2 μm.

(Preparation of anti-halation layer coating solution) Gelatin 17 g, polyacrylamide 9.6 g, solid fine particle dispersion (a) of the above base precursor (70 g), solid fine particle dispersion of the above dye 56 g, polymethyl methacrylate fine particles (average particle size 6.5 μm) 1.5 g, sodium polyethylene sulfonate 2.2 g, coloring dye compound (14) 0.2 g, H ₂ O 84
4 ml was mixed to prepare an antihalation layer coating solution.

(Preparation of back surface protective layer coating solution)
At 50 ° C., gelatin 50 g, polystyrene sodium sulfonate 0.2 g, N, N-ethylenebis (vinylsulfoneacetamide) 2.4 g, t-octylphenoxyethoxyethaneethanesulfonate 1 g, compound (15) 30 mg, C ₈ F
₁₇ SO ₃ K32 mg, C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH ₂ O) ₄ (CH ₂ ) ₄ -SO ₃ Na
64 mg and 950 ml of H ₂ O were mixed to prepare a back surface protective layer coating solution.

[0081]

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[0082]

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[0083]

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<< Preparation of Photothermographic Material >> On the back side of the above-mentioned undercoated polyethylene terephthalate film (support), an antihalation layer coating solution was applied at a solid content of solid fine particle dye of 0.04 g / m ² . The coating solution for the back surface protective layer was simultaneously and multi-layer coated so that the coating amount of gelatin was 1 g / m ^2, and dried to form an antihalation back layer. On the surface opposite to the back surface, the emulsion layer, the intermediate layer, the first protective layer, and the second protective layer were simultaneously coated in order from the undercoating surface by a slide bead coating method to prepare a photothermographic material sample. .

The coating was performed at a speed of 160 m / min, the distance between the tip of the coating die and the support was set to 0.18 mm, and the pressure in the decompression chamber was set 392 Pa lower than the atmospheric pressure. In the subsequent chilling zone, air with a dry-bulb temperature of 18 ° C and a wet-bulb temperature of 12 ° C was blown for 30 seconds to cool the coating liquid, and then the dry-bulb temperature was raised in the hovering-type floating type drying zone. Dry air at 30 ° C and a wet bulb temperature of 18 ° C was blown for 200 seconds to volatilize the solvent in the coating solution. The average wind speed of the air blown to the coating liquid film surface in the chilling zone and the drying zone was 7 m / sec.

(Evaluation of Character Missing) After the prepared photothermographic material sample was exposed to a “rose” character by using a semiconductor laser emitting at 660 nm and using a laser beam vertically multiplied by superimposing high-frequency waves, Thermal development was performed at 120 ° C. for 20 seconds with the plate heater type thermal developing apparatus 10 shown in FIG. 1 of the example of Japanese Patent Application Laid-Open No. 9-229684, and evaluated visually. However, use a metal mesh and activated carbon filter,
Turned off the smell.

○: Vivid. Δ: Slightly blurred, but within readable tolerance ×: Difficult to read. (Is a problem)

(Evaluation of Adhesive Property) After each photosensitive material was exposed to white light, it was heated and developed at 120 ° C. for 20 seconds, cut into a size of 3 cm square, and conditioned at 25 ° C. and 80% RH for 2 hours. The outermost surface protective layer (second protective layer) on the image recording surface and the outermost protective layer (back surface protective layer) on the back surface are overlapped so that they are in face-to-face contact, and stainless steel plates are stacked on both ends. Then, it was sealed in a moisture-proof envelope, placed on a 585 g weight, and stored at 40 ° C. for 3 days. Then take it out,
The adhesion area between the image recording surface and the back surface was visually evaluated.

：: good without adhesion marks Δ: slight adhesion marks but acceptable ×: adhesion marks (problem)

(Evaluation of Gamma Value) In the same manner as in the evaluation of missing characters, except that the step wedge was exposed, E1 and E2 were calculated, and the gamma value was obtained.

[0091]

[Table 1]

[0092]

[Table 2]

[0093]

[Table 3]

[0094]

[Table 4]

Example 2 A sample was prepared in the same manner as in Example 1 except that the emulsion layer was replaced with SBR latex using gelatin (equilibrium water content: 9%). Although the effect as in Example 1 was observed, the effect of improving the adhesiveness was found to be slightly lower.

[0096]

According to the present invention, it is possible to obtain a light-sensitive material which is free from characters and the like, has excellent visibility, and has good adhesion resistance.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a plate heater system.

FIG. 2 is a schematic cross-sectional view of a plate heater system.

Claims (5)

[Claims] In a photothermographic material having at least one photosensitive layer containing a photosensitive silver halide particle and a binder on a support, the size of the photosensitive silver halide particle is 0.001 μm or more. 04 μm or less,
A photothermographic material comprising a matting agent having an average particle size of 1 to 8 μm on the same side as the photosensitive layer, and having a gamma value of 2 to 65 obtained by heat development. 2. The photothermographic material according to claim 1, wherein the gamma value is 10 to 50. 3. The photosensitive layer is formed by applying a coating solution containing 30% by weight or more of water as a solvent and drying, and the main binder of the photosensitive layer has an equilibrium water content of 2 at 25 ° C. and 60% RH. 3. The photothermographic material according to claim 1, wherein the photothermographic material is a polymer in an amount of not more than weight%. 4. The method according to claim 1, wherein the support has at least two constituent layers, at least one photosensitive layer is provided, and the plurality of constituent layers are applied simultaneously. Photothermographic material. 5. The photothermographic material according to claim 1, wherein the photosensitive layer is a photothermographic material containing an organic silver salt, a reducing agent for silver ions, a binder, and a photosensitive silver halide. Photothermographic material.