JP2005010752A - Heat developable photosensitive material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material excellent in coating performance and having good conveyability in a heat developing machine and to provide an image forming method. <P>SOLUTION: The heat developable photosensitive material has an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on at least one face of a support and has at least one back layer and a back face protection layer on a face of the support opposite to the face with the image forming layer, wherein a binder in the back face protection layer contains a water-soluble polymer and a latex polymer having a glass transition temperature of -30 to +40°C. The image forming method is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photothermographic material and an image forming method thereof.

  In recent years, in the medical field, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental protection and space saving. Therefore, the photosensitive heat for medical diagnosis and photographic technology that can be efficiently exposed by a laser image setter or a laser imager and can form a clear black image having high resolution and sharpness. There is a need for techniques relating to developed photographic materials. These photosensitive photothermographic materials can eliminate the use of solution processing chemicals and supply customers with a simpler heat development processing system that does not damage the environment.

  Although there is a similar requirement in the field of general image forming materials, medical images are required to have high image quality with excellent sharpness and graininess because they are required to be finely drawn, and are cooled from the viewpoint of ease of diagnosis. There is a feature that a black tone image is preferred. At present, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems. However, there is no satisfactory output system for medical images.

  On the other hand, thermal image forming systems using organic silver salts are described in many documents (for example, see Patent Document 1, Patent Document 2, and Non-Patent Document 1). In particular, the photothermographic material generally contains a catalytically active amount of a photocatalyst (eg, silver halide), a reducing agent, a reducible silver salt (eg, an organic silver salt), and a color tone that controls the color tone of silver if necessary. And an image forming layer dispersed in a binder matrix. The photothermographic material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and blackened by a redox reaction between silver halide or a reducible silver salt (functioning as an oxidizing agent) and a reducing agent. Form a silver image. 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 exposure region (see, for example, Patent Document 3 and Patent Document 4). Fuji Medical Dry Imager FM-DPL was released as a medical image forming system using a photothermographic material.

In manufacturing a thermal image forming system using an organic silver salt, there are a method of manufacturing by solvent coating and a method of manufacturing by coating and drying a coating liquid containing polymer fine particles as a water dispersion as a main binder. Since the latter method does not require a process such as solvent recovery, the manufacturing equipment is simple and it is advantageous for mass production.
Here, the coating performance is a very important factor in the manufacturing process. In the water dispersion system, simultaneous multilayer coating is possible, and efficient production is possible. Improvement of coating performance is a problem that is eagerly awaited on a daily basis so that it can be manufactured more efficiently.

  As described above, high quality is required for the formed silver image. In addition to the requirement for a high quality image, there is a great demand for the physical characteristics of the light-sensitive material. This is because if an image is scratched during conveyance or processing, even if a high-quality image is obtained, it cannot be used. Especially for medical diagnosis, it may cause a misdiagnosis, so it is necessary to pay close attention. In recent years, rapid processing of a photothermographic material is required, and a photosensitive material is conveyed by a conveyance roller at a high speed, or is bent and conveyed with a sharp curvature in response to a demand for a compact developing machine. For this reason, the demands on the physical properties of the surface are increasing.

In particular, the photothermographic material, unlike liquid development, contains all chemical substances necessary for development in the photosensitive material. Further, all the composition remains in the photothermographic material even after development. Therefore, the addition of any additive to improve the physical properties of the surface can affect other materials. That is, it is very difficult to improve the surface characteristics simply by using an additive, and it is necessary to consider the trade-off between all the photothermographic materials and additives.
US Pat. No. 3,152,904 US Pat. No. 3,457,075 US Patent 2,910,377 Japanese Patent Publication No.43-4924 D. Klosterboer, “Thermally Processed Silver Systems” (Imaging Processes and Materials), 8th edition, J. Sturge. Walworth, edited by A. Shepp, Chapter 9, 279, 1989

  Accordingly, an object of the present invention is to provide a photothermographic material excellent in coating performance and good transportability in a heat developing machine, and an image forming method.

The object of the present invention has been achieved by the following photothermographic material and image forming method.
<1> An image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder is provided on at least one surface of the support, and the image forming layer is formed on the support. A photothermographic material having at least one back layer and a back surface protective layer on the side opposite to the surface having
A photothermographic material, wherein the binder of the back surface protective layer contains a water-soluble polymer and a latex polymer having a glass transition temperature of from -30 ° C to 40 ° C.
<2> The photothermographic material according to 1, wherein the latex polymer is contained in an amount of 5% by mass to 50% by mass with respect to all binders in the back surface protective layer.
<3> The photothermographic material according to 2, wherein the latex polymer is contained in an amount of 15% by mass to 40% by mass with respect to all binders in the back surface protective layer.
<4> The photothermographic material according to any one of <1> to <3>, wherein the latex polymer has a glass transition temperature of −30 ° C. or higher and 24 ° C. or lower.
<5> The latex polymer is at least one selected from the group consisting of acrylic, styrene, acrylic / styrene copolymer, styrene / butadiene copolymer, vinyl chloride, vinylidene chloride, and urethane. The photothermographic material according to any one of <1> to <4>, which is a polymer.
<6> The photothermographic material according to item 5, wherein the latex polymer is an acrylic latex polymer.
<7> The photothermographic material according to any one of <1> to <6>, wherein the latex polymer has an I / O value of 0.1 to 1.0.
<8> The photothermographic material according to item 7, wherein the I / O value is 0.5 or more and 0.9 or less.
<9> The photothermographic material according to any one of <1> to <8>, wherein the latex polymer contains an anionic surfactant.
<10> The photothermographic material according to 9, wherein the anionic surfactant is at least one selected from alkylbenzene sulfonates or sulfosuccinic acid diesters.
<11> The photothermographic material according to any one of <1> to <8>, wherein the water-soluble polymer is gelatin.
<12> The water-soluble polymer according to any one of <1> to <11>, wherein the water-soluble polymer is at least one selected from polyvinyl alcohols and acrylic acid-polyvinyl alcohol copolymer polymers. Photothermographic material.
<13> The thermal development according to any one of <1> to <12>, comprising a fluorine compound having a fluorinated alkyl group having 2 or more carbon atoms and 13 or less fluorine atoms. Photosensitive material.
<14> The photothermographic material according to item 13, wherein the fluorine compound has a fluorinated alkyl group having 5 to 9 fluorine atoms.
<15> An image forming method of a photothermographic material for forming an image with an image recording apparatus, wherein the image recording apparatus includes a heat developing unit having a driving roller and a plate heater, and the items <1> to <14 The surface of the surface of the photothermographic material having the image forming layer is brought into contact with the driving roller, and the surface of the photothermographic material having the back layer is placed on the plate. A method for forming an image of a photothermographic material, wherein the development is carried out by heating in contact with a heater.

In order to improve the coating performance and the transportability, which are the problems of the present invention, the present inventors have selected a substance most suitable for the back surface protective layer. This is because the back surface protective layer is in direct contact with the device by conveyance or the like.
As a result of intensive studies, the present inventors succeeded in solving the problem by using a water-soluble polymer and a latex polymer having a glass transition temperature of −30 ° C. or higher and 40 ° C. or lower as the outermost layer binder.

The present inventors have found an epoch-making finding that, when the glass transition temperature of the latex of the back surface protective layer is increased, the dynamic friction coefficient of the photosensitive material at a high temperature is remarkably increased. It was also found that the coefficient of dynamic friction at low temperatures does not depend on the glass transition temperature. This phenomenon is a finding that was not found by measuring the dynamic friction coefficient of the sensitive material near room temperature. That is, it has been found that the conveyance failure during the heat development depends on the glass transition temperature of the latex of the back surface protective layer. In particular, the occurrence of image unevenness is largely due to poor conveyance during thermal development, and it is extremely important to improve the conveyance property during thermal development in which the photosensitive material is heated.
Therefore, the present inventors have attempted to improve the transportability by reducing the glass transition temperature of the latex as much as possible in the binder of the back surface protective layer based on the above new knowledge, and have solved the problem.
On the other hand, it was also found that if the glass transition temperature of the latex is lowered too low, the transparency of the photosensitive material is lowered.
In consideration of all the above matters, the inventors have found that the optimal glass transition temperature of the latex used for the binder of the back surface protective layer is from −30 ° C. to 40 ° C., leading to the above invention <1>.

  Among these, it has also been found that the glass transition temperature is optimally from −30 ° C. to 24 ° C. This also takes into consideration the applicability during the production of the light-sensitive material (the invention <4> above).

  The optimum glass transition temperature of such a latex polymer is in the range when used in combination with a water-soluble polymer. When used in combination with a water-soluble polymer, there is an advantage that it is easy to apply.

  According to the present invention, it is possible to provide a photothermographic material and an image forming method which are excellent in coating performance and have good transportability in a thermal developing machine.

The photothermographic material and the image forming method of the present invention are described in detail below.
1. Photothermographic material The photothermographic material of the invention comprises at least one layer of image forming containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on at least one surface of a support. And having at least one back layer and a back surface protective layer on the surface opposite to the surface having the image forming layer with respect to the support. Further, a surface protective layer may be provided on the side opposite to the support of the image forming layer, and an intermediate layer may be provided between the surface protective layer and the image forming layer.

1-1. Back surface protective layer The back surface protective layer is not particularly limited as long as it contains a water-soluble polymer and a latex polymer having a glass transition temperature of -30 ° C or higher and 40 ° C or lower as a binder. Two or more back surface protective layers can be provided. When the back surface protective layer is two or more layers, at least the binder of the back surface protective layer farthest from the support contains a water-soluble polymer and a latex polymer having a glass transition temperature of −30 ° C. to 40 ° C. If you do.

(Latex polymer)
Preferred embodiments of the latex polymer used for the back surface protective layer include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (vinyl acetate) , Hydrophobic polymers such as poly (vinylidene chloride) s and poly (olefins). These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer.
In particular, the latex polymer is at least one polymer selected from the group consisting of acrylic, styrene, acrylic / styrene copolymer, styrene / butadiene copolymer, vinyl chloride, vinylidene chloride, and urethane. It is preferable that
These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the layer containing the latex is insufficient, and if it is too large, the film formability is poor and this is not preferred. An acrylic polymer latex is particularly preferably used.

In the photothermographic material of the present invention, the polymer latex that can be used as a binder is a water-insoluble hydrophobic polymer dispersed as fine particles in a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion is polymerized, the micelle is dispersed, or the polymer molecule has a partially hydrophilic structure and the molecular chain itself is molecularly dispersed. Anything may be used.
Having a partially hydrophilic structure is effective in stabilizing the dispersion state of the latex. For example, what has an anionic, cationic, or nonionic structure is mentioned. Among these, it is preferable to copolymerize acrylic acid, methacrylic acid or the like in order to have an anionic structure.

  In addition, when a surfactant is present during emulsion polymerization, the dispersion state is stabilized, and therefore it is preferable to use a surfactant in the emulsion polymerization step. Furthermore, it is preferable to add a surfactant to the back surface protective layer coating solution separately from the addition of the surfactant in the emulsion polymerization step. It is thought that it has the effect of stabilizing the latex. Particularly in the present invention, it is preferable to use an anionic surfactant as the separately added surfactant so as not to impair the transparency of the film.

  For polymer latex, see “Synthetic Resin Emulsion (Hiraku Okuda, Hiroshi Inagaki, Published by Polymer Press (1978))”, “Application of Synthetic Latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, edited by Koshihara) Publication (1993)), "chemistry of synthetic latex (by Soichi Muroi, published by Kobunshi Shuppankai (1970))" and JP-A No. 64-538.

  The average particle size of the dispersed particles is preferably 1 to 50000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

In particular, in the present invention, the latex polymer used for the back surface protective layer has a glass transition temperature (Tg) of −30 ° C. or higher and 40 ° C. or lower. Preferably, it is -30 degreeC or more and 24 degrees C or less, More preferably, it is -25 degreeC or more and 20 degrees C or less.
In order to improve the transportability, it is preferable to lower the Tg of the latex polymer as much as possible. The upper limit allowed for practical use is 40 ° C. Moreover, when Tg is higher than 40 ° C., it is difficult to apply uniformly, and there is a disadvantage that the coating solution must be applied while being heated to a high temperature.
On the other hand, when Tg is lower than −30 ° C., the transparency of the light-sensitive material is lowered, which is not preferable.

In this specification, Tg was calculated by the following formula.
1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the mass fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n. The homopolymer glass transition temperature value (Tgi) of each monomer was the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

  Two or more binders may be used in combination as required. Moreover, you may use combining glass transition temperature other than the said range. When two or more kinds of polymers having different Tg are blended and used, the mass average Tg may be in the above range.

  In the present invention, the latex polymer preferably has an I / O value of 0.1 or more and 1.0 or less. More preferably, it is 0.3 or more and 0.95 or less, and most preferably 0.5 or more and 0.9 or less. The I / O value is a value obtained by dividing an inorganic group based on an organic conceptual diagram by an organic group. It can be determined by the method described in "Organic Conceptual Diagram-Basics and Applications-" (1984, Yoshio Koda, Sankyo Publishing).

  Here, an organic conceptual diagram is an orthogonal coordinate system in which the properties of a compound are divided into an organic group representing a covalent bond and an inorganic group representing an ionic bond, and all organic compounds are named organic and inorganic axes. The inorganic value based on this is determined based on the hydroxyl group based on the inorganicity, that is, the influence of various substituents on the boiling point. If the distance between the boiling point curve of the straight-chain paraffin and the straight-line paraffin is about 100 ° C., the influence of one hydroxyl group is 100. On the other hand, the organic value is based on the number of carbon atoms that represent the methylene group in units of the number of methylene groups in the molecule. The average value of the boiling point increase due to addition of one carbon in the vicinity of 5 to 10 carbon atoms of the linear compound is 20 ° C., and this is a value determined as 20 on the basis of this. The inorganic value and the organic value are determined so as to correspond one-to-one on the graph. The I / O value is calculated from these values.

  Specific examples of the polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

Latex of P-1; -MMA (55) -EA (42) -MAA (3)-(Tg 39 ° C., I / O value 0.636)
P-2; latex of -MMA (47) -EA (50) -MAA (3)-(Tg 29 ° C., I / O value 0.636)
P-3; latex of -MMA (17) -EA (80) -MAA (3)-(Tg-4 ° C, I / O value 0.636)
P-4; Latex of -EA (97) -MAA (3)-(Tg-20 ° C, I / O value 0.636)
P-5; latex of -EA (97) -AA (3)-(Tg-21 ° C, I / O value 0.648)
P-6; Latex of -EA (90) -AA (10)-(Tg-15 ° C, I / O value 0.761)
P-7; latex of -MMA (50) -2EHA (35) -St (10) -AA (5)-(Tg 34 ° C., I / O value 0.461)
Latex of P-8; -MMA (30) -2EHA (55) -St (10) -AA (5)-(Tg 3 ° C., I / O value 0.398)
Latex of P-9; -MMA (10) -2EHA (75) -St (10) -AA (5)-(Tg-23 ° C., I / O value 0.339)
Latex of P-10; -MMA (60) -BA (36) -AA (4)-(Tg 29 ° C., I / O value 0.581)
Latex of P-11; -MMA (40) -BA (56) -AA (4)-(Tg-2 ° C, I / O value 0.545)
Latex of P-12; -MMA (25) -BA (71) -AA (4)-(Tg-22 ° C., I / O value 0.519)
Latex of P-13; -St (60) -BA (35) -AA (5)-(Tg-29 ° C, I / O value 0.250)
P-14; Latex of -St (40) -BA (55) -AA (5)-(Tg-2 ° C, I / O value 0.319)
Latex of P-15; -St (25) -BA (70) -AA (5)-(Tg-21 ° C, I / O value 0.377)
Latex of P-16; -MMA (58) -St (8) -BA (32) -AA (2)-(Tg 34 ° C., I / O value 0.515)
P-17; Latex of -MMA (50) -St (8) -BA (35) -HEMA (5) -AA (2)-(Tg 27 ° C., I / O value 0.542)
P-18; latex of -MMA (42) -St (8) -BA (43) -HEMA (5) -AA (2)-(Tg 14 ° C., I / O value 0.528)
P-19; Latex of -MMA (24) -St (8) -BA (61) -HEMA (5) -AA (2)-(Tg-12 ° C, I / O value 0.498)
Latex of P-20; -MMA (48) -St (8) -BA (27) -HEMA (15) -AA (2)-(Tg 39 ° C., I / O value 0.619)
P-21; latex of -EA (96) -AA (4)-(Tg-21 ° C, I / O value 0.664)
Latex of P-22; -EA (46) -MA (50) -AA (4)-(Tg-4 ° C., I / O value 0.739)
Latex of P-23; -EA (80) -HEMA (16) -AA (4)-(Tg-9 ° C, I / O value 0.775)
P-24; Latex of -EA (86) -HEMA (10) -AA (4)-(Tg-13 ° C, I / O value 0.733)
Latex of P-25; -St (45) -Bu (52) -MAA (3)-(Tg-26 ° C., I / O value 0.990)
Latex of P-26; -St (55) -Bu (42) -MAA (3)-(Tg-9 ° C, I / O value 0.105)
Latex of P-27; -St (60) -Bu (37) -MAA (3)-(Tg 1 ° C., I / O value 0.109)
Latex of P-28; -St (68) -Bu (29) -MAA (3)-(Tg 17 ° C., I / O value 0.114)
Latex of P-29; -St (75) -Bu (22) -MAA (3)-(Tg 34 ° C., I / O value 0.119)

  The abbreviations for the above structures represent the following monomers. MMA; methyl methacrylate, EA; ethyl acrylate, MA; methyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, HEMA; hydroxyethyl methacrylate, St; styrene, Bu; butadiene, AA; acrylic acid.

  After the synthesis, the latex polymer was adjusted to pH 6 with NaOH, and the surfactants shown in the table below were further added.

<Synthesis Example of Polymer Latex P-21>
770 g of distilled water bubbling nitrogen gas for 1 hour, 2.38 g of surfactant A-17, 11.38 g of ethyl acrylate and 0.47 g of acrylic acid were put into a 2 L three-necked flask, and the internal temperature reached 50 ° C. Heated until. When the temperature was stabilized, a solution prepared by dissolving 0.528 g of sodium bisulfite and 0.790 g of potassium persulfate in 60 g of distilled water was added thereto, and the mixture was stirred as it was for 30 minutes in a nitrogen atmosphere. A solution prepared by dissolving 0.528 g of sodium bisulfite and 0.790 g of potassium persulfate in 60 g of distilled water was added thereto, and a mixed solution of 216.05 g of ethyl acrylate and 9.00 g of acrylic acid was added in a nitrogen atmosphere for 90 minutes. Was added dropwise. A solution obtained by dissolving 0.528 g of sodium bisulfite and 0.790 g of potassium persulfate in 60 g of distilled water was added thereto, and the mixture was stirred as it was for 2 hours in a nitrogen atmosphere. The temperature was further raised to 90 ° C. and stirred for 1 hour in a nitrogen atmosphere. After the reaction was completed, the internal temperature was lowered to room temperature, 55 cc of 1N NaOH was added, and the mixture was stirred for 30 minutes. 142 cc of A-7 (5% by mass methanol / water (6/4) solution), 0.44 g of benzoisothiazolinone sodium salt and water were added to prepare a polymer latex having a concentration of 19.0% by mass. The obtained polymer latex dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored, and 1247 g of the exemplified compound P-21 (solid content: 19.0% by mass, granules) A diameter of 95 nm, pH 7.0) was obtained.

The polymer latex described above is also commercially available, and the following polymers can be used.
Examples of acrylic polymers include Sebian A-4635, 4718, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 855 (P-30: Tg 36 ° C.), (Nippon Zeon) Voncoat R3370 (P-31: Tg25 ° C), 4280 (P-32: Tg15 ° C) (manufactured by Dainippon Ink & Chemicals, Inc.), and the like.
Examples of poly (esters) include FINETEX ES650, 611, 675, and 850 (manufactured by Dainippon Ink Chemical Co., Ltd.), WD-size, and WMS (manufactured by Eastman Chemical).
Examples of the poly (urethane) s include HYDRAN AP10 (P-33: Tg 37 ° C.), 20, 30, 101H, Vonic 1320NS, 1610NS (manufactured by Dainippon Ink and Chemicals, Inc.).
Examples of rubbers include LACSTAR 7310K, 3307B (P-34: Tg13 ° C.), 4700H (Dainippon Ink Chemical Co., Ltd.), 410, 430, 435, 110, 415A (P-35: Tg27 ° C.), 438C (manufactured by Nippon Zeon Co., Ltd.).
Examples of poly (vinyl chloride) include G351 and G576 (manufactured by Nippon Zeon Co., Ltd.).
Examples of poly (vinylidene chloride) s include L502, L513 (manufactured by Asahi Kasei Kogyo Co., Ltd.), D-5071 (P-36: Tg 36 ° C.) (manufactured by Dainippon Ink & Chemicals, Inc.), and the like. .
Examples of poly (olefin) s include Chemipearl S120, SA100 (more from Mitsui Petrochemical Co., Ltd.), Voncoat 2830 (P-37: Tg 38 ° C.), 2210, 2960 (more from Dainippon Ink Chemical Co., Ltd.). And so on.

  As the anionic surfactant that can be used in the back surface protective layer according to the present invention, surfactants such as alkylbenzene sulfonates and sulfosuccinic acid diester salts can be used. Specific examples are given below.

The amount of the latex polymer used is preferably 5% by mass or more and 50% by mass or less with respect to the total binder in the back surface protective layer. When the amount is 5% by mass or less, the effect of the present invention is hardly obtained. When the amount is 50% by mass or more, the film strength as the back protective layer is lowered, and the scratch resistance and adhesion are deteriorated. A more preferable range is 10% by mass or more and 45% by mass or less, and a particularly preferable range is 15% by mass or more and 40% by mass or less.
In addition to the latex polymer, the following water-soluble polymers are contained. A polymer other than the latex polymer and the water-soluble polymer may be contained in the binder.

(Water-soluble polymer)
The water-soluble polymer in the present invention may be a polymer derived from animal protein or a polymer not derived from animal protein. In the present invention, the animal protein-derived polymer refers to a water-soluble polymer derived from a natural animal protein such as glue, casein, gelatin, or egg white. These may be chemically modified.
The polymer derived from animal protein is preferably gelatin, and there are acid-treated gelatin and alkali-treated gelatin (such as lime treatment) depending on the synthesis method, and both can be preferably used. It is preferable to use gelatin having a molecular weight of 10,000 to 1,000,000. In addition, modified gelatin modified by utilizing the amino group or carboxyl group of gelatin can be used (for example, phthalated gelatin).

  In the present invention, the water-soluble polymer not derived from animal protein means natural polymer (polysaccharide, microbial, animal) other than animal protein such as gelatin, semi-synthetic polymer (cellulose, starch, alginic acid). ) And synthetic polymers (vinyl and others). This includes synthetic polymers such as polyvinyl alcohol described below, and natural or semi-synthetic polymers made from plant-derived cellulose or the like. Polyvinyl alcohols and acrylic acid-vinyl alcohol copolymer polymers are preferable.

1) Polyvinyl alcohols Polyvinyl alcohols are preferred as water-soluble polymers not derived from animal proteins in the present invention.
As polyvinyl alcohol (PVA) preferably used in the present invention, there are various saponification degrees, polymerization degrees, neutralization degrees, modified products, and copolymers with various monomers as listed below.

  As a completely saponified product, PVA-105 [polyvinyl alcohol (PVA) content 94.0% by mass or more, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.5% by mass or less, volatile content 5 0.0 mass% or less, viscosity (4 mass%, 20 ° C.) 5.6 ± 0.4 CPS], PVA-110 [PVA content 94.0 mass%, saponification degree 98.5 ± 0.5 mol%, acetic acid Sodium content 1.5% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 11.0 ± 0.8 CPS], PVA-117 [PVA content 94.0% by mass, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 28.0 ± 3.0 CPS], PVA-117H [ PVA content 93.5% by mass, saponification degree 99.6 ± 0.3 mol% Sodium acetate content 1.85% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 29.0 ± 3.0 CPS], PVA-120 [PVA content 94.0% by mass, saponification Degree 98.5 ± 0.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 39.5 ± 4.5 CPS], PVA-124 [PVA content 94.0% by mass, saponification degree 98.5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 60 0.0 ± 6.0 CPS], PVA-124H [PVA content 93.5% by mass, saponification degree 99.6 ± 0.3 mol%, sodium acetate content 1.85% by mass, volatile matter 5.0% by mass , Viscosity (4 mass%, 20 ° C.) 61.0 ± 6.0 CPS], PVA-CS [PVA Proportion 94.0% by mass, saponification degree 97.5 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 27.5 ± 3.0 CPS], PVA-CST [PVA content 94.0% by mass, saponification degree 96.0 ± 0.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4 mass%, 20 ° C.) 27.0 ± 3.0 CPS], PVA-HC [PVA content 90.0 mass%, saponification degree 99.85 mol% or more, sodium acetate content 2.5 mass%, volatilization 8.5% by mass, viscosity (4% by mass, 20 ° C.) 25.0 ± 3.5 CPS] (all are trade names manufactured by Kuraray Co., Ltd.) and the like.

  As a partially saponified product, PVA-203 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4 mass%, 20 ° C.) 3.4 ± 0.2 CPS], PVA-204 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass %, Volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 3.9 ± 0.3 CPS], PVA-205 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.5 Mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 5.0 ± 0.4 CPS], PVA-210 [PVA content 94.0% by mass %, Saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatilization 5.0 mass%, viscosity (4 mass%, 20 ° C.) 9.0 ± 1.0 CPS], PVA-217 [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, acetic acid Sodium content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 22.5 ± 2.0 CPS], PVA-220 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 30.0 ± 3.0 CPS], PVA-224 [ PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 44. 0 ± 4.0 CPS], PVA-228 [PVA content 94.0% by mass, saponification degree 88.0 ± 1.5 %, Sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 65.0 ± 5.0 CPS], PVA-235 [PVA content 94.0 mass %, Saponification degree 88.0 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 95.0 ± 15.0 CPS], PVA-217EE [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20% ° C) 23.0 ± 3.0 CPS], PVA-217E [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5. 0% by mass, viscosity (4% by mass, 20 ° C.) 23.0 ± 3.0 CPS], PVA-22 E [PVA content 94.0% by mass, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0% by mass, volatile matter 5.0% by mass, viscosity (4% by mass, 20 ° C.) 31.0 ± 4.0 CPS], PVA-224E [PVA content 94.0 mass%, saponification degree 88.0 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass %, Viscosity (4 mass%, 20 ° C.) 45.0 ± 5.0 CPS], PVA-403 [PVA content 94.0 mass%, saponification degree 80.0 ± 1.5 mol%, sodium acetate content 1 0.0 mass%, volatile matter 5.0 mass%, viscosity (4 mass%, 20 ° C.) 3.1 ± 0.3 CPS], PVA-405 [PVA content 94.0 mass%, saponification degree 81.5 ± 1.5 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass%, viscosity (4 mass %, 20 ° C.) 4.8 ± 0.4 CPS], PVA-420 [PVA content 94.0% by mass, saponification degree 79.5 ± 1.5 mol%, sodium acetate content 1.0% by mass, volatilization Min 5.0 mass%], PVA-613 [PVA content 94.0 mass%, saponification degree 93.5 ± 1.0 mol%, sodium acetate content 1.0 mass%, volatile content 5.0 mass% , Viscosity (4 mass%, 20 ° C.) 16.5 ± 2.0 CPS], L-8 [PVA content 96.0 mass%, saponification degree 71.0 ± 1.5 mol%, sodium acetate content 1. 0 mass% (ash content), volatile content 3.0 mass%, viscosity (4 mass%, 20 ° C.) 5.4 ± 0.4 CPS] (all are trade names manufactured by Kuraray Co., Ltd.), etc. Can do.

  In addition, said measured value was calculated | required according to JISK-6726-1977.

  The modified polyvinyl alcohol can be selected from cationic modification, anion modification, modification with -SH compound, modification with alkylthio compound, and modification with silanol. In addition, modified polyvinyl alcohol described in “Poval” by Koichi Nagano et al.

  As such modified polyvinyl alcohol (modified PVA), C polymer as C-118, C-318, C-318-2A, C-506 (all are trade names manufactured by Kuraray Co., Ltd.), HL polymer HL-12E, HL-1203 (all are trade names made by Kuraray Co., Ltd.), HM polymer is HM-03, HM-N-03 (all are trade names made by Kuraray Co., Ltd.), KL-118, KL-318, KL-506, KM-118T, KM-618 (all are trade names manufactured by Kuraray Co., Ltd.) as the K polymer, and M-115 (manufactured by Kuraray Co., Ltd.) as the M polymer. (Trade name), MP-102, MP-202, MP-203 (all are trade names made by Kuraray Co., Ltd.) as MP polymers, and MPK-1, MPK- as MPK polymers. , MPK-3, MPK-4, MPK-5, MPK-6 (all are trade names manufactured by Kuraray Co., Ltd.), R-1130, R-2105, R-2130 (all are all as R polymers) Kuraray Co., Ltd. product name), V polymer V-2250 (Kuraray Co., Ltd. product name) and the like.

  Polyvinyl alcohol can be adjusted in viscosity or stabilized by a small amount of solvent or inorganic salt added to the aqueous solution. For details, refer to the above-mentioned document “Poval” Koichi Nagano et al. Publications described on pages 144 to 154 can be used. As a typical example, it is possible to improve the coating surface quality by containing boric acid, which is preferable. The addition amount of boric acid is preferably 0.01 to 40% by mass with respect to polyvinyl alcohol.

Polyvinyl alcohol is described in the above-mentioned document “Poval” that crystallinity is improved by heat treatment and water resistance is improved, but it is heated at the time of coating and drying, or additional overheating after drying. Since water resistance improves by processing, it is especially preferable for the present invention among water-soluble polymers.
In order to further increase the water resistance, it is preferable to add a waterproofing agent as described in pages 256 to 261 of the same document. For example, aldehydes, methylol compounds (N-methylol urea, N-methylol melamine, etc.), activated vinyl compounds (divinyl sulfone and derivatives thereof, etc.), bis (β-hydroxyethyl sulfone), epoxy compounds (epichlorohydrin, Derivatives thereof), polycarboxylic acids (dicarboxylic acids, polycarboxylic acids such as polyacrylic acid, methyl vinyl ether-maleic acid copolymers, isobutylene-maleic anhydride copolymers), diisocyanates, inorganic crosslinking agents (Cu , B, Al, Ti, Zr, Sn, V, Cr, etc.).
Examples of the water-resistant agent that is preferable according to the present invention include inorganic crosslinking agents, among which boric acid and its derivatives are preferable, and boric acid is particularly preferable. Hereinafter, specific examples of boric acid derivatives will be given.

  The addition amount of these water-resistant agents is preferably adjusted within a range of 0.01 to 40% by mass with respect to polyvinyl alcohol.

  Examples of the water-soluble polymer that is not derived from animal protein in the present invention include the following in addition to the polyvinyl alcohol.

Specific examples include plant-based polysaccharides such as gum arabic, κ-carrageenan, ι-carrageenan, λ-carrageenan, guar gum (such as Supercol from Squalon), locust bean gum, pectin, tragacanth, corn starch (National Starch & Chemical Co. Purity-21 etc.), phosphorylated starch (National Star & Chemical Co. National 78-1898 etc.) and the like.
Examples of microbial polysaccharides include xanthan gum (Kelco's Keltrol T, etc.) and dextrin (National Starch & Chemical Co., Nadex 360, etc.). It is done.
Alternatively, as a cellulose polymer, ethyl cellulose (ICFA Cellofas WLD, etc.), carboxymethyl cellulose (Daicel CMC, etc.), hydroxyethyl cellulose (Daicel HEC, etc.), hydroxypropyl cellulose (Aqualon Klucel, etc.), methylcellulose, etc. (Viscontran manufactured by Henkel, etc.), nitrocellulose (Isopropyl Wet manufactured by Hercules, etc.), cationized cellulose (Crodacel QM manufactured by Croda, etc.) and the like. Examples of the alginic acid system include sodium alginate (Keltone from Kelco), propylene glycol alginate, and other classifications such as cationized guar gum (such as Hi-care 1000 from Alcolac) and sodium hyaluronate (such as Hyalure from Lifecare Biomedia). .
In addition, agar, farsellan, guar gum, karaya gum, larch gum, guar seed gum, sylum seed gum, kins seed gum, tamarind gum, gellan gum, tara gum and the like can be mentioned. Among these, those having high water solubility are preferable, and those that become an aqueous solution that can be sol-gel modified within 24 hours due to a temperature change in a temperature range of 5 ° C. to 95 ° C. are preferably used.

  Synthetic polymers include acrylic poly-sodium acrylate, polyacrylic acid copolymer, polyacrylamide, polyacrylamide copolymer, etc., vinyl-based polyvinyl pyrrolidone, polyvinyl pyrrolidone copolymer, etc. Glycol, polypropylene glycol, polyvinyl ether, polyethyleneimine, polystyrene sulfonic acid or copolymer thereof, polyvinyl sulfonic acid or copolymer thereof, polyacrylic acid or copolymer thereof, acrylic acid or copolymer thereof, and maleic acid Copolymer, maleic acid monoester copolymer, acryloylmethylpropanesulfonic acid or a copolymer thereof, and the like.

Further, the superabsorbent polymers described in US Pat. No. 4,960,681, JP-A-62-245260, etc., that is, —COOM or —SO ₃ M (M is a hydrogen atom or an alkali metal). Homopolymers of vinyl monomers having styrene or copolymers of these vinyl monomers or other vinyl monomers (for example, sodium methacrylate, ammonium methacrylate, Sumikagel L-5H manufactured by Sumitomo Chemical Co., Ltd.) can also be used. .

  Among these, the water-soluble polymer preferably used is Sumikagel L-5H manufactured by Sumitomo Chemical Co., Ltd.

  In the binder of the back surface protective layer, the water-soluble polymer is preferably contained in an amount of 50% by mass to 95% by mass. More preferably, it is 55 mass% or more and 90 mass% or less. Most preferably, it is 60 mass% or more and 85 mass% or less.

(Binder coating amount)
The amount of these binders, the coating amount is preferably 0.1 g / m ² or more 5 g / m ² or less as (support 1 m ² per), 0.5 g / m ² or more 3 g / m ² or less is more preferable.

(Other compositions)
In the present invention, the back surface protective layer may contain various additives such as a matting agent, a hardener, a fluorosurfactant, a matting agent, a filter dye, and a crosslinking agent.
Further, a film-forming auxiliary may be added to control the minimum film-forming temperature of the polymer latex. The film-forming aid is also called a temporary plasticizer and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. For details, see "Synthetic Latex Chemistry (by Soichi Muroi, published by Kobunshi Shuppankai (1970))". Preferred film-forming aids are the following compounds, but the compounds that can be used in the present invention are not limited to the following specific examples.
Z-1: benzyl alcohol Z-2: 2,2,4-trimethylpentanediol-1,3-monoisobutyrate Z-3: 2-dimethylaminoethanol Z-4: diethylene glycol

  In particular, it is preferable to add a film-forming auxiliary, and the addition amount is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, based on the solid content of the polymer latex in the coating solution for the protective layer. % Is preferred.

1-2. Back Layer In the present invention, a back layer is provided on the side of the support opposite to the image forming layer. The back layer applicable to the present invention is described in paragraph Nos. 0128 to 0130 of JP-A No. 11-65021.

In the present invention, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver color tone and the temporal change of the image. Such colorants are disclosed in JP-A-62-210458, JP-A-63-104046, JP-A-63-103235, JP-A-63-208846, JP-A-63-306436, JP-A-63-141435, and JP-A-01-61745. No. 1, Japanese Patent Laid-Open No. 2001-100363, and the like.
Such a colorant is usually added in the range of 0.1 mg / m ^{2 to 1} g / m ² , and the layer to be added is preferably a back layer provided on the opposite side of the photosensitive layer.
In order to adjust the base color tone, it is preferable to use a dye having an absorption peak at 580 to 680 nm. As the dye for this purpose, azomethine-based oil-soluble dyes described in JP-A-4-359967 and JP-A-4-359968 having a small absorption intensity on the short wavelength side, and phthalocyanine-based water-soluble dyes described in Japanese Patent Application No. 2002-96797 are preferable. The dye for this purpose may be added to any layer, but is more preferably added to the non-photosensitive layer on the emulsion surface side or the back surface side.

1-3. Anti-halation layer In the photothermographic material of the invention, the anti-halation layer can be provided on the side farther from the light source than the photosensitive layer. The anti-halation layer may be the back layer. Further, it may be a layer between the support and the image forming layer.

As for the antihalation layer, paragraphs 0123 to 0124 of JP-A-11-65021, JP-A-11-223898, 9-230531, 10-36695, 10-104779, 11-231457, 11 -352625, 11-352626 and the like.
The antihalation layer contains an antihalation dye having absorption at the exposure wavelength. In the case where the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable.
When antihalation is performed using a dye having absorption in the visible range, it is preferable that substantially no dye color remains after image formation, and a means for decoloring by the heat of heat development is used. In particular, it is preferable to add a thermally decoloring dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These techniques are described in JP-A-11-231457 and the like.

The amount of decoloring dye added is determined by the use of the dye. In general, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1. The optical density is preferably 0.15 to 2, and more preferably 0.2 to 1. The amount of dye used to obtain such an optical density is generally about 0.001 to 1 g / m ² .

When the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.
In the thermal decoloration using such decoloring dye and base precursor, a substance (for example, diphenylsulfone, which lowers the melting point by 3 ° C. (deg) or more when mixed with a base precursor as described in JP-A No. 11-352626). 4-Chlorophenyl (phenyl) sulfone), 2-naphthyl benzoate and the like are preferably used in view of thermal decoloring properties and the like.

1-4. Image-forming layer The image-forming layer in the invention is composed of one or more layers on a support. In the case of a single layer, it consists of an organic silver salt, a photosensitive silver halide, a reducing agent and a binder, and optionally contains additional materials such as toning agents, coating aids and other auxiliary agents. In the case of two or more layers, the first image forming layer (usually a layer adjacent to the support) contains an organic silver salt and a light-sensitive silver halide, and some of the second image forming layer or both layers include Must contain other ingredients. The construction of a multicolor photosensitive photothermographic material may include a combination of these two layers for each color and all components in a single layer as described in US Pat. No. 4,708,928. May be included. In the case of a multi-dye multicolor photosensitive photothermographic material, each image-forming layer is generally functional or non-functional between each image-forming layer as described in US Pat. No. 4,460,681. By using a sex barrier layer, they are kept distinct from each other.
The main composition of the image forming layer will be described in detail below.

(Organic silver salt)
1) Composition The organic silver salt that can be used in the present invention is relatively stable to light, but is heated to 80 ° C. or higher in the presence of an exposed photosensitive silver halide and a reducing agent. In this case, the silver salt functions as a silver ion supplier to form a silver image. The organic silver salt may be any organic substance that can supply silver ions that can be reduced by a reducing agent. Regarding such non-photosensitive organic silver salt, paragraph numbers 0048 to 0049 of JP-A-10-62899, page 18 line 24 to page 19 line 37 of European Patent Publication No. 0803764A1, European Patent Publication. No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, and the like. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids (having 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Preferable examples of the fatty acid silver salt include silver lignocerate, silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver erucate and the like. Including a mixture of In the present invention, among these fatty acid silvers, the silver behenate content is preferably 50 mol% to 100 mol%, more preferably 85 mol% to 100 mol%, still more preferably 95 mol% to 100 mol%. The following fatty acid silver is preferably used. Furthermore, it is preferable to use fatty acid silver having a silver erucate content of 2 mol% or less, more preferably 1 mol% or less, and still more preferably 0.1 mol% or less.

  Moreover, it is preferable that silver stearate content rate is 1 mol% or less. By making the stearic acid content 1 mol% or less, a silver salt of an organic acid having a low Dmin, high sensitivity and excellent image storage stability can be obtained. As said stearic acid content rate, 0.5 mol% or less is preferable and it is especially preferable not to contain substantially.

  Furthermore, when silver arachidate is included as the silver salt of the organic acid, the silver arachidate content is 6 mol% or less to obtain a low Dmin and an organic acid silver salt excellent in image storability. It is preferable at a point and it is still more preferable that it is 3 mol% or less.

2) Shape The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a flake shape.
In the present invention, scaly organic silver salts are preferred. In addition, short needle-shaped, rectangular parallelepiped, cubic or potato-shaped irregular particles having a major axis / uniaxial length ratio of less than 5 are also preferably used. These organic silver particles have a feature that there is less fog at the time of thermal development than long needle-like particles having a ratio of the major axis to the uniaxial length of 5 or more. In particular, particles having a major axis / uniaxial ratio of 3 or less are preferable because the mechanical stability of the coating film is improved. In the present specification, the scaly organic silver salt is defined as follows. The organic acid silver salt was observed with an electron microscope, the shape of the organic acid silver salt particle was approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped were designated a, b, and c from the shortest side (c was the same as b). Then, the shorter numerical values a and b are calculated, and x is obtained as follows.
x = b / a

  In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 15 ≧ x (average) ≧ 1.5. Incidentally, the needle shape is 1 ≦ x (average) <1.5.

  In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.3 μm or less, and more preferably 0.1 μm or more and 0.23 μm or less. The average c / b is preferably 1 or more and 9 or less, more preferably 1 or more and 6 or less, still more preferably 1 or more and 4 or less, and most preferably 1 or more and 3 or less.

By setting the equivalent sphere diameter to 0.05 μm or more and 1 μm or less, aggregation is hardly caused in the photosensitive material, and image storability is improved. The sphere equivalent diameter is preferably 0.1 μm or more and 1 μm or less. In the present invention, the method for measuring the equivalent sphere diameter is obtained by directly photographing a sample using an electron microscope and then image-processing the negative.
In the flake shaped particles, the spherical equivalent diameter / a of the particles is defined as the aspect ratio. The aspect ratio of the flake shaped particles is preferably 1.1 or more and 30 or less, more preferably 1.1 or more and 15 or less, from the viewpoint of preventing aggregation in the photosensitive material and improving the image storage stability. .

  The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. It is as follows. The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, it is obtained from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to the temporal change of the fluctuation of the scattered light. Can do.

3) Preparation Known methods and the like can be applied to the production and dispersion method of organic acid silver used in the present invention. For example, the above-mentioned JP-A-10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, JP-A-2001-163889, 2001-163890, 2001-163828, 2001-33907, 2001-188313, 2001-83651, 2002-6442, 2002-49117, 2002-31870, 2002-107868 You can refer to the issue.

  In addition, when the photosensitive silver salt is allowed to coexist at the time of dispersion of the organic silver salt, the fog is increased and the sensitivity is remarkably lowered. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. In the present invention, the amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is preferably 1 mol% or less, more preferably 0.1 mol% relative to 1 mol of the organic acid silver salt in the liquid. The following is more preferable, and positive addition of photosensitive silver salt is not performed.

  In the present invention, it is possible to produce a photosensitive material by mixing an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion, but the mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose. The ratio of the photosensitive silver salt to the organic silver salt is preferably in the range of 1 mol% to 30 mol%, more preferably in the range of 2 mol% to 20 mol%, particularly 3 mol% to 15 mol%. Mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a method preferably used for adjusting photographic characteristics.

4) Addition amount The organic silver salt in the present invention can be used in a desired amount, but the total coating silver amount including silver halide is preferably 0.1 to 5.0 g / m ² , more preferably 0.3. It is -3.0 g / m < ² >, More preferably, it is 0.5-2.0 g / m < ² >. In particular, in order to improve image storability, the total coated silver amount is preferably 1.8 g / m ² or less, more preferably 1.6 g / m ² or less. If the preferred reducing agent in the present invention is used, a sufficient image density can be obtained even with such a low silver amount.

(Reducing agent)
The photothermographic material of the invention preferably contains a heat developer that is a reducing agent for the organic silver salt. The reducing agent for the organic silver salt may be any substance (preferably an organic substance) that reduces silver ions to metallic silver. Examples of such reducing agents are described in JP-A No. 11-65021, paragraphs 0043 to 0045, and European Patent Publication No. 0803764A1, page 7, line 34 to page 18, line 12.
In the present invention, the reducing agent is preferably a so-called hindered phenol-based reducing agent or bisphenol-based reducing agent having a substituent at the ortho position of the phenolic hydroxyl group, and more preferably a compound represented by the following general formula (R).
Formula (R)

(In the general formula (R), R ¹¹ and R ¹¹ ′ each independently represents an alkyl group having 1 to 20 carbon atoms. R ¹² and R ¹² ′ are each independently a substituent capable of substituting for a hydrogen atom or a benzene ring. the representative .L -S- group or a -CHR ¹³ - group .R ¹³ is hydrogen atom or a benzene ring .X ¹ and X ¹ 'each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms Represents a substitutable group.)

The general formula (R) will be described in detail.
1) R ¹¹ and R ¹¹ '
R ¹¹ and R ¹¹ ′ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and the substituent of the alkyl group is not particularly limited, but is preferably an aryl group, a hydroxy group, Examples thereof include an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, an acyl group, a carbamoyl group, an ester group, a ureido group, a urethane group, and a halogen atom.

2) R ¹² and R ¹² ', X ¹ and X ^1'
R ¹² and R ¹² ′ each independently represent a hydrogen atom or a substituent that can be substituted on a benzene ring, and X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. Preferred examples of each group that can be substituted on the benzene ring include an alkyl group, an aryl group, a halogen atom, an alkoxy group, and an acylamino group.

3) L
L represents an —S— group or a —CHR ¹³ — group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent. Specific examples of the unsubstituted alkyl group represented by R ¹³ include a methyl group, an ethyl group, a propyl group, a butyl group, a heptyl group, an undecyl group, an isopropyl group, a 1-ethylpentyl group, and a 2,4,4-trimethylpentyl group. can give. Examples of the substituent for the alkyl group can include, similar to substituent of R ^11, halogen atom, alkoxy group, alkylthio group, aryloxy group, arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group, an oxycarbonyl group, Examples thereof include a carbamoyl group and a sulfamoyl group.

4) Preferred substituents R ¹¹ and R ¹¹ ′ are preferably secondary or tertiary alkyl groups having 3 to 15 carbon atoms, specifically isopropyl, isobutyl, t-butyl, t-amyl groups. , T-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like. R ¹¹ and R ¹¹ ′ are more preferably a tertiary alkyl group having 4 to 12 carbon atoms, and among them, a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a t-butyl group is most preferable. .

R ¹² and R ¹² ′ are preferably an alkyl group having 1 to 20 carbon atoms, and specifically include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, and a cyclohexyl group. Group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, methoxyethyl group and the like. More preferred are methyl group, ethyl group, propyl group, isopropyl group and t-butyl group.
X ¹ and X ¹ ′ are preferably a hydrogen atom, a halogen atom, or an alkyl group, and more preferably a hydrogen atom.

L is preferably a —CHR ¹³ — group.
R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and the alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4,4-trimethylpentyl group. R ¹³ is particularly preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group or an isopropyl group.

When R ¹³ is a hydrogen atom, R ¹² and R ¹² ′ are preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group.
When R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, R ¹² and R ¹² ′ are preferably methyl groups. As the primary or secondary alkyl group having 1 to 8 carbon atoms for R ^13, a methyl group, an ethyl group, a propyl group, or an isopropyl group is more preferable, and a methyl group, an ethyl group, or a propyl group is still more preferable.
When all of R ¹¹ , R ¹¹ ′, R ¹² and R ¹² ′ are methyl groups, R ¹³ is preferably a secondary alkyl group. In this case, the secondary alkyl group of R ¹³ is preferably an isopropyl group, an isobutyl group, or a 1-ethylpentyl group, and more preferably an isopropyl group.
The reducing agent has different heat developability and developed silver tone depending on the combination of R ¹¹ , R ¹¹ ′, R ¹² , R ¹² ′ and R ¹³ . Since these can be adjusted by combining two or more kinds of reducing agents, it is preferable to use two or more kinds in combination depending on the purpose.

  Although the specific example of the reducing agent of this invention including the compound represented with general formula (R) in this invention below is shown, this invention is not limited to these.

Examples of preferable reducing agents in the present invention other than those described above are the compounds described in JP-A Nos. 2001-188314, 2001-209145, 2001-350235, and 2002-156727.
The addition amount of the reducing agent is preferably a ^{0.1g / m 2 ~3.0g / m 2} , more preferably ^{0.2g / m 2 ~1.5g / m 2} , more preferably 0 .3 g / m ^{2 to} 1.0 g / m ² . It is preferably contained in an amount of 5 mol% to 50 mol%, more preferably 8 mol% to 30 mol%, and more preferably 10 mol% to 20 mol%, based on 1 mol of silver on the surface having the image forming layer. More preferably. The reducing agent is preferably contained in the image forming layer.

The reducing agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.
Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. The method of producing is mentioned.

Further, as a solid fine particle dispersion method, a reducing agent powder is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to produce a solid dispersion. A method is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the Zr content in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem.
The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).
Particularly preferred is a solid particle dispersion method of a reducing agent, and it is preferable to add fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

(Development accelerator)
In the photothermographic material of the present invention, a sulfonamide phenol compound represented by the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234, or the like as a development accelerator, Hindered phenol compounds represented by general formula (II) described in JP-A No. 2001-92075, general formula (I) described in JP-A Nos. 10-62895 and 11-15116, A hydrazine-based compound represented by the general formula (D) of JP-A No. 2002-156727 or the general formula (1) described in JP-A No. 2002-278017, and described in the specification of JP-A No. 2001-264929 Phenol-based or naphthol-based compounds represented by the general formula (2) are preferably used. These development accelerators are used in the range of 0.1 mol% to 20 mol% with respect to the reducing agent, preferably in the range of 0.5 mol% to 10 mol%, more preferably 1 mol% to 5 mol. % Range. The introduction method to the light-sensitive material includes the same method as the reducing agent, but it is particularly preferable to add as a solid dispersion or an emulsion dispersion. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high-boiling solvent and a low-boiling auxiliary solvent that are solid at room temperature, or as a so-called oilless emulsified dispersion that does not use a high-boiling solvent. It is preferable to add.
In the present invention, among the above development accelerators, hydrazine compounds represented by the general formula (D) described in JP-A No. 2002-156727 and those described in JP-A No. 2001-264929 are general. A phenol-based or naphthol-based compound represented by the formula (2) is more preferable.

Particularly preferred development accelerators in the invention are compounds represented by the following general formulas (A-1) and (A-2).
Formula (A-1)
Q ₁ -NHNH-Q ₂
(Wherein Q ₁ represents an aromatic group or a heterocyclic group bonded to —NHNH—Q ₂ at a carbon atom, and Q ₂ represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, Or represents a sulfamoyl group.)

In the general formula (A-1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, thiophene ring, etc. are preferable, and these Also preferred are fused rings in which the rings are fused together.

  These rings may have a substituent, and when they have two or more substituents, these substituents may be the same or different. Examples of substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, arylsulfonamido groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, carbamoyl groups, sulfamoyl groups, cyano Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have substituents. Examples of preferred substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, aryls. Sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, and acyloxy group Can be mentioned.

The carbamoyl group represented by Q ₂ is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms. For example, unsubstituted carbamoyl, methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbamoyl N-sec-butylcarbamoyl, N-octylcarbamoyl, N-cyclohexylcarbamoyl, N-tert-butylcarbamoyl, N-dodecylcarbamoyl, N- (3-dodecyloxypropyl) carbamoyl, N-octadecylcarbamoyl, N- {3 -(2,4-tert-pentylphenoxy) propyl} carbamoyl, N- (2-hexyldecyl) carbamoyl, N-phenylcarbamoyl, N- (4-dodecyloxyphenyl) carbamoyl, N- (2-chloro-5 Dodecyloxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl include N- benzylcarbamoyl.

The acyl group represented by Q ₂ is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2 -Hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, 2-hydroxymethylbenzoyl. The alkoxycarbonyl group represented by Q2 is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, dodecyl. Examples include oxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ₂ is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples thereof include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q2 is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, 3-dodecyl. Examples include oxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, and 4-dodecyloxyphenylsulfonyl.

The sulfamoyl group represented by Q ₂ is preferably a sulfamoyl group having 0 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as an unsubstituted sulfamoyl group, an N-ethylsulfamoyl group, N- (2- Ethylhexyl) sulfamoyl, N-decylsulfamoyl, N-hexadecylsulfamoyl, N- {3- (2-ethylhexyloxy) propyl} sulfamoyl, N- (2-chloro-5-dodecyloxycarbonylphenyl) sulfamoyl, N- (2-tetradecyloxyphenyl) sulfamoyl is mentioned. The group represented by Q ₂ may further have a group exemplified as an example of the substituent of the 5- to 7-membered unsaturated ring represented by Q ₁ at a substitutable position. When it has two or more substituents, these substituents may be the same or different.

Next, a preferable range of the compound represented by formula (A-1) is described. Q ₁ is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, pyrimidine ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring. 1,2,4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, and these rings Is more preferably a ring fused with a benzene ring or an unsaturated heterocycle. Q ₂ is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on a nitrogen atom.

Formula (A-2)

In the general formula (A-2), R ₁ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate ester group. R ₃ and R ₄ each represents a group that can be substituted on the benzene ring mentioned in the example of the substituent of formula (A-1). R ₃ and R ₄ may be connected to each other to form a condensed ring.
R ₁ is preferably an alkyl group having 1 to 20 carbon atoms (for example, methyl group, ethyl group, isopropyl group, butyl group, tert-octyl group, cyclohexyl group, etc.), acylamino group (for example, acetylamino group, benzoylamino group, methyl group). Ureido group, 4-cyanophenylureido group, etc.), carbamoyl group (n-butylcarbamoyl group, N, N-diethylcarbamoyl group, phenylcarbamoyl group, 2-chlorophenylcarbamoyl group, 2,4-dichlorophenylcarbamoyl group, etc.) acylamino Groups (including ureido groups and urethane groups) are more preferred. R2 is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (for example, methoxy group, butoxy group, n-hexyloxy group, n-decyloxy group, cyclohexyloxy group, benzyloxy group, etc.), aryloxy A group (phenoxy group, naphthoxy group, etc.).
R ₃ is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, and most preferably a halogen atom. R ₄ is preferably a hydrogen atom, an alkyl group or an acylamino group, more preferably an alkyl group or an acylamino group. Examples of these preferable substituents are the same as those for R ₁ . When R ₄ is an acylamino group, R ₄ is preferably linked to R ₃ to form a carbostyryl ring.

In the general formula (A-2), when R ₃ and R ₄ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. The same substituent as the example of a substituent quoted by general formula (A-1) may couple | bond with the naphthalene ring. When general formula (A-2) is a naphthol-based compound, R ₁ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ₂ is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

  Hereinafter, preferred specific examples of the development accelerator in the present invention will be given. The present invention is not limited to these.

(Hydrogen bonding compound)
When the reducing agent in the present invention has an aromatic hydroxyl group (—OH) or amino group (—NHR, R is a hydrogen atom or an alkyl group), particularly in the case of the aforementioned bisphenols, these groups and hydrogen bonds It is preferable to use together a non-reducing compound having a group capable of forming.
Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. Can be mentioned. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (however, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a urethane group. (However, it has no> N—H group and is blocked like> N—Ra (Ra is a substituent other than H)), a ureido group (however, it has no> N—H group,> N-Ra (Ra is a substituent other than H).)
In the present invention, a particularly preferred hydrogen bonding compound is a compound represented by the following general formula (D).
Formula (D)

In the general formula (D), R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be substituted even if they are unsubstituted. You may have.
When R ²¹ to R ²³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group. Preferred examples of the substituent include an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, and a t-octyl group. Group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like.
Specific examples of the alkyl group represented by R ²¹ to R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, Examples include 1-methylcyclohexyl group, benzyl group, phenethyl group, 2-phenoxypropyl group and the like.
Examples of the aryl group include phenyl group, cresyl group, xylyl group, naphthyl group, 4-t-butylphenyl group, 4-t-octylphenyl group, 4-anisidyl group, and 3,5-dichlorophenyl group.
Alkoxy groups include methoxy, ethoxy, butoxy, octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy, dodecyloxy, cyclohexyloxy, 4-methylcyclohexyloxy, benzyl An oxy group etc. are mentioned.
Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, and a biphenyloxy group.
Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. .

R ²¹ to R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In view of the effects of the present invention, at least one of R ²¹ to R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, it is preferable that R ²¹ to R ²³ are the same group in that they can be obtained at low cost.
Specific examples of the hydrogen bonding compound including the compound of the general formula (D) in the present invention are shown below, but the present invention is not limited thereto.

Specific examples of the hydrogen bonding compound include those described in European Patent No. 1096310, Japanese Patent Application Laid-Open No. 2002-156727, and Japanese Patent Application Laid-Open No. 2002-318431.
The compound represented by the general formula (D) in the present invention can be used in a light-sensitive material by being incorporated in a coating solution in the form of a solution, an emulsified dispersion, or a solid dispersion fine particle dispersion in the same manner as the reducing agent. It is preferable to use it as a product. These compounds form a hydrogen-bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state, and depending on the combination of the reducing agent and the compound of the general formula (D) in the present invention, the compound may be crystallized as a complex. It can be isolated in the state.
The use of the crystal powder isolated in this way as a solid dispersed fine particle dispersion is particularly preferable for obtaining stable performance. Further, a method in which the reducing agent and the compound of the general formula (D) in the present invention are mixed in a powder and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.
The compound of the general formula (D) in the present invention is preferably used in the range of 1 mol% to 200 mol%, more preferably in the range of 10 mol% to 150 mol%, more preferably relative to the reducing agent. Is in the range of 20 mol% to 100 mol%.

(Photosensitive silver halide)
1) Halogen composition The photosensitive silver halide used in the present invention is not particularly limited as a halogen composition. Silver chloride, silver chlorobromide, silver bromide, silver iodobromide, silver iodochlorobromide, silver iodide Can be used. Of these, silver bromide, silver iodobromide and silver iodide are preferred. 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 technique for localizing silver bromide or silver iodide on the surface of silver chloride, silver bromide or silver chlorobromide grains can also be preferably used.

2) Grain Forming Methods Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. In particular, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound into gelatin or another polymer solution, and then mixed with an organic silver salt. Use the method. Further, the method described in paragraph Nos. 0217 to 0224 of JP-A No. 11-119374, and the methods described in JP-A Nos. 11-352627 and 2000-347335 are also preferable.

3) Grain size The grain size of the photosensitive silver halide is preferably small for the purpose of keeping the cloudiness after image formation low, specifically 0.20 μm or less, more preferably 0.01 μm or more and 0.15 μm or less. More preferably, it is 0.02 μm or more and 0.12 μm or less. The grain size here means the diameter when converted into a circular image having the same area as the projected area of silver halide grains (in the case of tabular grains, the projected area of the main plane).

4) Grain shape Examples of the shape of the silver halide grains include cubes, octahedrons, tabular grains, spherical grains, rod-like grains, and potato grains. In the present invention, cubic grains are particularly preferred. Grains with rounded corners of silver halide grains can also be preferably used. The surface index (Miller index) on the outer surface of the photosensitive silver halide grain is not particularly limited, but the ratio of the {100} plane, which has high spectral sensitizing efficiency when adsorbed by the spectral sensitizing dye, is high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more. The ratio of the Miller index {100} plane is determined by T.T. Tani; Imaging Sci. 29, 165 (1985).

5) Heavy Metal The photosensitive silver halide grain in the invention can contain a metal or metal complex of Group 8 to Group 10 of the Periodic Table (showing Groups 1 to 18). As the central metal of the group 8 to group 10 metal or metal complex of the periodic table, rhodium, ruthenium and iridium are preferable. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol with ^respect to 1 mol of silver. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.

In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. The hexacyano metal complexes include [Fe (CN) ₆ ] ⁴⁻ , [Fe (CN) ₆ ] ³⁻ , [Ru (CN) ₆ ] ⁴⁻ , [Os (CN) ₆ ] ⁴⁻ , [Co ( CN) ₆ ] ³⁻ , [Rh (CN) ₆ ] ³⁻ , [Ir (CN) ₆ ] ³⁻ , [Cr (CN) ₆ ] ³⁻ , [Re (CN) ₆ ] ^{3− and the} like. . In the present invention, a hexacyano Fe complex is preferred.

  The hexacyano metal complex is present in the form of ions in aqueous solution, so the counter cation is not important, but it is easy to mix with water and is suitable for precipitation of silver halide emulsions. Sodium ion, potassium ion, rubidium It is preferable to use alkali metal ions such as ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ions, tetraethylammonium ions, tetrapropylammonium ions, tetra (n-butyl) ammonium ions).

  In addition to water, the hexacyano metal complex is miscible with a mixed solvent or gelatin with an appropriate organic solvent miscible with water (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.). Can be added.

The addition amount of the hexacyano metal complex is preferably 1 × 10 ⁻⁵ mol or more and 1 × 10 ⁻² mol or less, more preferably 1 × 10 ⁻⁴ mol or more and 1 × 10 ⁻³ mol or less per mol of silver.

  In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grain, the chalcogen sensitization of sulfur sensitization, selenium sensitization and tellurium sensitization is completed after the addition of the silver nitrate aqueous solution used for grain formation. It is added directly before the completion of the preparation step before the chemical sensitization step for performing noble metal sensitization such as sensitization and gold sensitization, during the washing step, during the dispersion step, or before the chemical sensitization step. In order to prevent the silver halide fine grains from growing, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add it before the completion of the preparation step.

  The addition of the hexacyano metal complex may be started after adding 96% by mass of the total amount of silver nitrate to be added to form grains, more preferably starting after adding 98% by mass, The addition of 99% by mass is particularly preferable.

  When these hexacyanometal complexes are added after the addition of the aqueous silver nitrate solution just before the completion of grain formation, they can be adsorbed on the outermost surface of the silver halide grains, and most of them form slightly soluble salts with silver ions on the grain surface. To do. Since this silver salt of hexacyanoiron (II) is a less soluble salt than AgI, it is possible to prevent re-dissolution by fine particles and to produce silver halide fine particles having a small particle size. .

Furthermore, regarding the metal atoms (for example, [Fe (CN) ₆ ] ⁴⁻ ) that can be contained in the silver halide grains used in the present invention, the method of desalting silver halide emulsions and the method of chemical sensitization, JP-A-11-11 No. 84574, paragraph numbers 0046 to 0050, JP-A No. 11-65021, paragraph numbers 0025 to 0031, and JP-A No. 11-119374, paragraph numbers 0242 to 0250.

6) Gelatin As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. It is necessary to maintain a good dispersion state of the photosensitive silver halide emulsion in the coating solution containing an organic silver salt, and gelatin having a molecular weight of 10,000 to 1,000,000 is preferably used. It is also preferable to phthalate the gelatin substituent. These gelatins may be used at the time of grain formation or at the time of dispersion after desalting, but are preferably used at the time of grain formation.

7) Sensitizing Dye Sensitizing dyes applicable to the present invention are those that can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and are suitable for the spectral characteristics of the exposure light source. Sensitizing dyes with sensitivity can be advantageously selected. Regarding the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A-11-65021, compounds represented by the general formula (II) of JP-A-10-186572, and general formulas (I) of JP-A-11-119374 ) And the dye described in Example 5 of U.S. Pat. Nos. 5,510,236 and 3,871,887, JP-A-2-96131, JP-A-59-48753. No. 19, line 38 to page 20, line 35 of JP-A-0803764A1, JP-A No. 2001-272747, JP-A No. 2001-290238, JP-A No. 2002-23306, etc. It is described in. These sensitizing dyes may be used alone or in combination of two or more. In the present invention, the time when the sensitizing dye is added to the silver halide emulsion is preferably the time from the desalting step to the coating, and more preferably the time from desalting to the end of chemical ripening.
The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with the sensitivity and fogging performance, but is preferably 10 ⁻⁶ to 1 mol, more preferably 1 mol per mol of silver halide in the photosensitive layer. Is 10 ⁻⁴ to 10 ⁻¹ mol.

  In the present invention, a supersensitizer can be used to improve spectral sensitization efficiency. As the supersensitizer used in the present invention, European Patent Publication No. 587,338, US Pat. Nos. 3,877,943, 4,873,184, JP-A-5-341432, 11- 109547, 10-111543, etc. are mentioned.

8) Chemical Sensitization The photosensitive silver halide grain in the invention is preferably chemically sensitized by sulfur sensitizing method, selenium sensitizing method or tellurium sensitizing method. As the compound preferably used in the sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds such as compounds described in JP-A-7-128768 can be used. In the present invention, tellurium sensitization is particularly preferred. The compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, and the general formulas (II), (III), (IV) described in JP-A-5-313284 The compound shown by is more preferable.

  The photosensitive silver halide grains in the present invention are preferably chemically sensitized by gold sensitization alone or in combination with the chalcogen sensitization described above. As the gold sensitizer, the valence of gold is preferably +1 or +3, and the gold sensitizer is preferably a commonly used gold compound. Typical examples include chloroauric acid, bromoauric acid, potassium chloroaurate, potassium bromoaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate, pyridyltrichlorogold. Etc. are preferable. Further, gold sensitizers described in US Pat. No. 5,858,637 and JP-A No. 2002-278016 are also preferably used.

In the present invention, chemical sensitization can be performed at any time after particle formation and before coating. After desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, (3) spectral After sensitization, there may be (4) immediately before application.
The amount of sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, etc., but is preferably 10 ⁻⁸ to 10 ⁻² mol per mol of silver halide, preferably About 10 ⁻⁷ to 10 ⁻³ mol is used.
The amount of the gold sensitizer added varies depending on various conditions, but as a guide, it is 10 ⁻⁷ mol to 10 ⁻³ mol, more preferably 10 ⁻⁶ mol to 5 × 10 ⁻⁴ mol per mol of silver halide. .
The conditions for chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is about 40 ° C to 95 ° C.
A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method described in European Patent Publication No. 293,917.

  A reducing agent is preferably used for the photosensitive silver halide grains in the present invention. As specific compounds for the reduction sensitization, ascorbic acid and thiourea dioxide are preferable, and in addition, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, and the like are preferably used. . The reduction sensitizer may be added at any stage in the photosensitive emulsion production process from crystal growth to the preparation process immediately before coating. Further, reduction sensitization is preferable by ripening while maintaining the pH of the emulsion at 7 or more or pAg at 8.3 or less, and reduction sensitization is achieved by introducing a single addition portion of silver ions during grain formation. It is also preferable to do.

9) Compound in which 1-electron oxidant produced by 1-electron oxidation can emit 1 electron or more electrons In the photothermographic material of the present invention, 1-electron oxidant produced by 1-electron oxidation is 1 electron or It is preferable to contain a compound capable of emitting more electrons. The compound can be used alone or in combination with the above-described various chemical sensitizers, and can increase the sensitivity of silver halide.

  The one-electron oxidant produced by one-electron oxidation contained in the photothermographic material of the present invention is a compound selected from the following types 1 to 5 that can emit one or more electrons.

(Type 1)
A compound in which a one-electron oxidant produced by one-electron oxidation can further emit two or more electrons with a subsequent bond cleavage reaction.
(Type 2)
The one-electron oxidant produced by one-electron oxidation is a compound capable of releasing another electron with a subsequent bond cleavage reaction, and has two or more adsorbing groups for silver halide in the same molecule. Compound.
(Type 3)
A compound in which a one-electron oxidant produced by one-electron oxidation can further emit one or more electrons after a subsequent bond formation process.
(Type 4)
A compound capable of emitting one or more electrons after the one-electron oxidant produced by one-electron oxidation undergoes a subsequent intramolecular ring-cleaving reaction.
(Type 5)
In the compound represented by XY, X represents a reducing group, Y represents a leaving group, and a one-electron oxidant formed by one-electron oxidation of the reducing group represented by X is followed by XY A compound capable of releasing Y by releasing Y with a bond cleavage reaction and releasing another electron therefrom.

  Preferred among the compounds of type 1 and type 3 to 5 are “compounds having an adsorptive group to silver halide in the molecule” or “partial structure of spectral sensitizing dye in the molecule”. Compound ". More preferred is a “compound having an adsorptive group to silver halide in the molecule”. The compounds of types 1 to 4 are more preferably “compounds having a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as an adsorptive group”.

The compounds of types 1 to 5 will be described in detail.
In the compound of type 1, “bond cleavage reaction” specifically means cleavage of a bond between carbon-carbon, carbon-silicon, carbon-hydrogen, carbon-boron, carbon-tin, and carbon-germanium elements, These may be further accompanied by carbon-hydrogen bond cleavage. A type 1 compound is a compound capable of emitting two or more (preferably three or more) electrons for the first time after a one-electron oxidation to form a one-electron oxidant, followed by a bond cleavage reaction.

  A preferable compound among the compounds of type 1 is represented by general formula (A), general formula (B), general formula (1), general formula (2), or general formula (3).

Formula (A)

In the general formula (A), RED ₁₁ represents a reducing group that can be oxidized by one electron, and L ₁₁ represents a leaving group. R ₁₁₂ represents a hydrogen atom or a substituent. R ₁₁₁ together with the carbon atom (C) and RED ₁₁ may form a cyclic structure corresponding to a tetrahydro, hexahydro, or octahydro form of a 5- or 6-membered aromatic ring (including an aromatic heterocycle). Represents a metal atomic group.

In the general formula (B), RED ₁₂ represents a reducing group that can be oxidized by one electron, and L ₁₂ represents a leaving group. R ₁₂₁ and R ₁₂₂ each represent a hydrogen atom or a substituent. ED ₁₂ represents an electron donating group. In the general formula (B), R ₁₂₁ and RED ₁₂ , R ₁₂₁ and R ₁₂₂ , or ED ₁₂ and RED ₁₂ may be bonded to each other to form a cyclic structure.

These compounds represented by the general formula (A) or the general formula (B) are capable of spontaneously cleaving L ₁₁ or L ₁₂ after the reducing group represented by RED ₁₁ or RED ₁₂ is oxidized by one electron. It is a compound that can release two or more, preferably three or more electrons in association with separation by reaction.

In the general formula (1), Z ₁ represents an atomic group capable of forming a 6-membered ring together with a nitrogen atom and two carbon atoms of the benzene ring, R ₁ , R ₂ and R _N1 each represents a hydrogen atom or a substituent, X ₁ represents a substituent substitutable on the benzene ring, m ₁ represents an integer of 0 to 3, and L ₁ represents a leaving group. In the general formula (2), ED ₂₁ represents an electron donating group, R ₁₁ , R ₁₂ , R _N21 , R ₁₃ , and R ₁₄ each represents a hydrogen atom or a substituent, and X ₂₁ is a substituent capable of substituting for a benzene ring. Represents a group, m ₂₁ represents an integer of 0 to 3, and L ₂₁ represents a leaving group. R _N21 , R ₁₃ , R ₁₄ , X ₂₁ and ED ₂₁ may be bonded to each other to form a cyclic structure. In the general formula (3), R ₃₂ , R ₃₃ , R ₃₁ , R _N31 , R _a and R _b each represent a hydrogen atom or a substituent, and L ₃₁ represents a leaving group. However, when R _N31 represents a group other than an aryl group, R _a and R _b are bonded to each other to form an aromatic ring.

After these compounds are oxidized by one electron, L ₁ , L ₂₁ , or L ₃₁ is spontaneously released by a bond cleavage reaction, and accordingly, two or more electrons, preferably three or more, can be emitted. A compound.

Hereinafter, the compound represented by the general formula (A) will be described in detail first.
The reducing group that can be oxidized by one electron represented by RED ₁₁ in the general formula (A) is a group that can be bonded to R ₁₁₁ described later to form a specific ring, specifically, the following monovalent group: And a divalent group obtained by removing one hydrogen atom at a suitable position for ring formation. For example, alkylamino group, arylamino group (anilino group, naphthylamino group etc.), heterocyclic amino group (benzthiazolylamino group, pyrrolylamino group etc.), alkylthio group, arylthio group (phenylthio group etc.), heterocyclic thio Group, alkoxy group, aryloxy group (phenoxy group etc.), heterocyclic oxy group, aryl group (phenyl group, naphthyl group, anthranyl group etc.), aromatic or non-aromatic heterocyclic group (5-membered to 7-membered) , A monocyclic or condensed ring hetero ring containing at least one hetero atom among nitrogen atom, sulfur atom, oxygen atom and selenium atom. Specific examples thereof include, for example, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinoxaline ring , Tetrahydroquinazoline ring, indoline ring, indole ring, indazole , Carbazole ring, phenoxazine ring, phenothiazine ring, benzothiazoline ring, pyrrole ring, imidazole ring, thiazoline ring, piperidine ring, pyrrolidine ring, morpholine ring, benzimidazole ring, benzimidazoline ring, benzoxazoline ring, methylenedioxyphenyl ring (Hereinafter, RED ₁₁ is described as a monovalent group name for convenience). RED ₁₁ may have a substituent.

  In the present invention, the substituent means a substituent selected from the following groups unless otherwise specified. Halogen atoms, alkyl groups (including aralkyl groups, cycloalkyl groups, active methine groups, etc.), alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups (regardless of the position of substitution), quaternized nitrogen atoms Heterocyclic group (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxy group or salt thereof, sulfonylcarbamoyl group, acylcarbamoyl group, sulfa Moylcarbamoyl group, carbazoyl group, oxalyl group, oxamoyl group, cyano group, carbonimidoyl group, thiocarbamoyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group units repeatedly), aryloxy group , F B-ringoxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group Thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, (alkyl or aryl) sulfonylureido group, Acylureido group, acylsulfamoylamino group, nitro group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfini Group, a sulfo group or a salt thereof, sulfamoyl group, sulfonylsulfamoyl group or a salt thereof, phosphoric acid amide or a group containing a phosphoric acid ester structure and so forth. These substituents may be further substituted with these substituents.

RED ₁₁ is preferably an alkylamino group, an arylamino group, a heterocyclic amino group, an aryl group, an aromatic or non-aromatic heterocyclic group, more preferably an arylamino group (particularly an anilino group), an aryl group ( Especially a phenyl group). When these have a substituent, the substituent is preferably a halogen atom, an alkyl group, an alkoxy group, a carbamoyl group, a sulfamoyl group, an acylamino group, or a sulfonamide group.
However, when RED ₁₁ represents an aryl group, the aryl group preferably has at least one “electron-donating group”. Here, the “electron donating group” means a hydroxy group, an alkoxy group, a mercapto group, a sulfonamide group, an acylamino group, an alkylamino group, an arylamino group, a heterocyclic amino group, an active methine group, and a nitrogen atom in the ring. 5-membered, monocyclic or condensed, electron-rich aromatic heterocyclic group (for example, indolyl group, pyrrolyl group, imidazolyl group, benzimidazolyl group, thiazolyl group, benzthiazolyl group, indazolyl group) containing at least one, nitrogen A non-aromatic nitrogen-containing heterocyclic group (a group that can also be called a cyclic amino group such as a pyrrolidinyl group, an indolinyl group, a piperidinyl group, a piperazinyl group, or a morpholino group) substituted with an atom. Here, the active methine group means a methine group substituted by two “electron-withdrawing groups”, and the “electron-withdrawing group” means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, It means a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, or a carbonimidoyl group. Here, the two electron withdrawing groups may be bonded to each other to form a cyclic structure.

In the general formula (A), L ₁₁ is specifically a carboxy group or a salt thereof, a silyl group, a hydrogen atom, a triarylboron anion, a trialkylstannyl group, a trialkylgermyl group, or —CR _C1 R _C2 R Represents the _C3 group. Here, the silyl group specifically represents a trialkylsilyl group, an aryldialkylsilyl group, a triarylsilyl group, or the like, and may have an arbitrary substituent.

When L ₁₁ represents a salt of a carboxy group, examples of the counter ion forming the salt include alkali metal ions, alkaline earth metal ions, heavy metal ions, ammonium ions, phosphonium ions, and the like, preferably alkali metal ions or ammonium ions. Alkali metal ions (particularly Li ⁺ , Na ⁺ , K ⁺ ions) are most preferred.

When L ₁₁ represents a —CR _C1 R _C2 R _C3 group, R _C1 , R _C2 and R _C3 are each independently a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkylthio group, arylthio group, alkyl Represents an amino group, an arylamino group, a heterocyclic amino group, an alkoxy group, an aryloxy group, or a hydroxy group, which may be bonded to each other to form a cyclic structure, and further have an optional substituent. Also good. However, when one of R _C1 , R _C2 and R _C3 represents a hydrogen atom or an alkyl group, the remaining two do not represent a hydrogen atom or an alkyl group. R _C1 , R _C2 and R _C3 are preferably each independently an alkyl group, aryl group (particularly phenyl group), alkylthio group, arylthio group, alkylamino group, arylamino group, heterocyclic group, alkoxy group, hydroxy group Specific examples thereof include phenyl group, p-dimethylaminophenyl group, p-methoxyphenyl group, 2,4-dimethoxyphenyl group, p-hydroxyphenyl group, methylthio group, phenylthio group, phenoxy group, Examples include methoxy group, ethoxy group, dimethylamino group, N-methylanilino group, diphenylamino group, morpholino group, thiomorpholino group, hydroxy group and the like. Examples of the case where they are bonded to each other to form a cyclic structure include 1,3-dithiolan-2-yl group, 1,3-dithian-2-yl group, N-methyl-1,3-thiazolidine-2 -Yl group, N-benzyl-benzothiazolidin-2-yl group and the like.
-CR _C1 R _C2 R _C3 group represents the same group as the residue obtained by removing L ₁₁ from general formula (A) as a result of selection within the ranges described above for R _C1 , R _C2 and R _C3 , respectively. Is also preferred.

In the general formula (A), L ₁₁ is preferably a carboxy group or a salt thereof, and a hydrogen atom. More preferred is a carboxy group or a salt thereof.

When L ₁₁ represents a hydrogen atom, the compound represented by the general formula (A) preferably has a base site inherent in the molecule. By the action of this base moiety, after the compound represented by the general formula (A) is oxidized, the hydrogen atom represented by L ₁₁ is deprotonated and further electrons are emitted therefrom.

Here, the base is specifically a conjugate base of an acid having a pKa of about 1 to about 10. For example, nitrogen-containing heterocycles (pyridines, imidazoles, benzimidazoles, thiazoles, etc.), anilines, trialkylamines, amino groups, carbon acids (active methylene anions, etc.), thioacetic acid anions, carboxylates (- COO ⁻ ), sulfate (—SO ₃ ⁻ ), amine oxide (> N ⁺ (O ⁻ ) —) and the like. Preferably, it is a conjugate base of an acid having a pKa of about 1 to about 8, more preferably carboxylate, sulfate, or amine oxide, and particularly preferably carboxylate. When these bases have anions, they may have counter cations, examples of which include alkali metal ions, alkaline earth metal ions, heavy metal ions, ammonium ions, phosphonium ions and the like. These bases are linked to the compound represented by the general formula (A) at an arbitrary position. The position at which these base sites are bonded may be any of RED ₁₁ , R ₁₁₁ and R _{112 in} the general formula (A), and may be linked to a substituent of these groups.

In the general formula (A), R ₁₁₂ represents a hydrogen atom or a substituent that can be substituted with a carbon atom. However, R ₁₁₂ does not represent the same group as L ₁₁ .
R ₁₁₂ is preferably a hydrogen atom, an alkyl group, an aryl group (such as a phenyl group), an alkoxy group (such as a methoxy group, an ethoxy group, or a benzyloxy group), a hydroxy group, an alkylthio group (such as a methylthio group or a butylthio group), or an amino group , An alkylamino group, an arylamino group, and a heterocyclic amino group, more preferably a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, a phenyl group, and an alkylamino group.

In the general formula (A), the cyclic structure formed by R ₁₁₁ is a ring structure corresponding to a tetrahydro, hexahydro or octahydro form of a 5-membered or 6-membered aromatic ring (including an aromatic heterocycle). The hydro form means a ring structure in which a carbon-carbon double bond (or carbon-nitrogen double bond) inherent in an aromatic ring (including an aromatic heterocycle) is partially hydrogenated, The body means two structures, the hexahydro form means three, and the octahydro form means four structures in which carbon-carbon double bonds (or carbon-nitrogen double bonds) are hydrogenated. By being hydrogenated, the aromatic ring becomes a partially hydrogenated non-aromatic ring structure.
Specifically, pyrrolidine ring, imidazolidine ring, thiazolidine ring, pyrazolidine ring and oxazolidine ring, piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, piperazine ring, tetralin ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring, And tetrahydroquinoxaline ring, tetrahydrocarbazole ring, octahydrophenanthridine ring and the like. These ring structures may have an arbitrary substituent.

More preferably, the cyclic structure formed by R ₁₁₁ is more preferably a pyrrolidine ring, imidazolidine ring, piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, piperazine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring, tetrahydroquinoxaline ring, tetrahydroquinone ring Carbazole ring, particularly preferably pyrrolidine ring, piperidine ring, piperazine ring, tetrahydropyridine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring, tetrahydroquinoxaline ring, most preferably pyrrolidine ring, piperidine ring, tetrahydro ring A pyridine ring, a tetrahydroquinoline ring, and a tetrahydroisoquinoline ring.

In the general formula (B), RED ₁₂ and L ₁₂ are groups having the same meanings as RED ₁₁ and L ₁₁ in the general formula (A), respectively, and preferred ranges thereof are also the same. However, RED ₁₂ is a monovalent group except for the case where the following cyclic structure is formed, and specific examples thereof include groups having the monovalent group name described in RED ₁₁ . R ₁₂₁ and R ₁₂₂ are groups having the same meaning as R ₁₁₂ in formula (A), and preferred ranges thereof are also the same. ED ₁₂ represents an electron donating group. R ₁₂₁ and RED ₁₂ , R ₁₂₁ and R ₁₂₂ , or ED ₁₂ and RED ₁₂ may be bonded to each other to form a cyclic structure.

The electron donating group represented by ED ₁₂ in the general formula (B) is the same as the electron donating group described as a substituent when RED ₁₁ represents an aryl group. ED ₁₂ is preferably a hydroxy group, an alkoxy group, a mercapto group, a sulfonamide group, an alkylamino group, an arylamino group, an active methine group, a 5-membered monocyclic or condensed ring containing at least one nitrogen atom in the ring. , An electron-excess aromatic heterocyclic group, a non-aromatic nitrogen-containing heterocyclic group substituted with a nitrogen atom, and a phenyl group substituted with these electron-donating groups, and further a hydroxy group, a mercapto group, a sulfonamide group, Alkylamino group, arylamino group, active methine group, non-aromatic nitrogen-containing heterocyclic group substituted with nitrogen atom, and phenyl group substituted with these electron-donating groups (for example, p-hydroxyphenyl group, p-dialkylamino) A phenyl group, an o, p-dialkoxyphenyl group and the like are more preferable.

In the general formula (B), R ₁₂₁ and RED ₁₂ , R ₁₂₂ and R ₁₂₁ , or ED ₁₂ and RED ₁₂ may be bonded to each other to form a cyclic structure. The cyclic structure formed here is a non-aromatic carbocyclic or heterocyclic ring, which is a 5-membered to 7-membered monocyclic or condensed ring, and is a substituted or unsubstituted cyclic structure. When R ₁₂₁ and RED ₁₂ form a ring structure, specific examples thereof include the pyrroline ring, imidazoline ring, thiazoline in addition to the examples of the cyclic structure formed by R ₁₁₁ in formula (A). Ring, pyrazoline ring, oxazoline ring, indane ring, morpholine ring, indoline ring, tetrahydro-1,4-oxazine ring, 2,3-dihydrobenzo-1,4-oxazine ring, tetrahydro-1,4-thiazine ring, 2 , 3-dihydrobenzo-1,4-thiazine ring, 2,3-dihydrobenzofuran ring, 2,3-dihydrobenzothiophene ring and the like. When ED ₁₂ and RED ₁₂ form a ring structure, ED ₁₂ preferably represents an amino group, an alkylamino group, or an arylamino group. Specific examples of the formed ring structure include a tetrahydropyrazine ring, a piperazine ring, A tetrahydroquinoxaline ring, a tetrahydroisoquinoline ring, etc. are mentioned. When R ₁₂₂ and R ₁₂₁ form a ring structure, specific examples thereof include a cyclohexane ring and a cyclopentane ring.

Next, general formulas (1) to (3) will be described.
In the general formulas (1) to (3), R ₁ , R ₂ , R ₁₁ , R ₁₂ and R ₃₁ are groups having the same meaning as R _{112 in the} general formula (A), and preferred ranges thereof are also the same. L ₁ , L ₂₁ and L ₃₁ represent the same leaving groups as those exemplified as specific examples in the description of L _{11 in the} general formula (A), and preferred ranges thereof are also the same. The substituents represented by X ₁ and X ₂₁ are the same as the examples of the substituent when RED ₁₁ of the general formula (A) has a substituent, and the preferred range is also the same. m ₁ and m ₂₁ are preferably integers of 0 to 2, more preferably 0 or 1.

When R _N1 , R _N21 , or R _N31 represents a substituent, the substituent is preferably an alkyl group, an aryl group, or a heterocyclic group, and these may further have an arbitrary substituent. R _N1 , R _N21 and R _N31 are preferably a hydrogen atom, an alkyl group or an aryl group, more preferably a hydrogen atom or an alkyl group.

When R ₁₃ , R ₁₄ , R ₃₃ , R _a and R _b represent a substituent, the substituent is preferably an alkyl group, aryl group, acyl group, alkoxycarbonyl group, carbamoyl group, cyano group, alkoxy group, acylamino Group, sulfonamido group, ureido group, thioureido group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group and the like.

The 6-membered ring formed by Z ₁ in the general formula (1) is a non-aromatic heterocycle condensed with the benzene ring of the general formula (1). Specifically, as a ring structure including the condensed benzene ring, A tetrahydroquinoline ring, a tetrahydroquinoxaline ring, and a tetrahydroquinazoline ring, preferably a tetrahydroquinoline ring and a tetrahydroquinoxaline ring. These may have a substituent.

In the general formula (2), ED ₂₁ is a group having the same meaning as ED _{12 in the} general formula (B), and the preferred range thereof is also the same.

In the general formula (2), any two of R _N21 , R ₁₃ , R ₁₄ , X ₂₁ and ED ₂₁ may be bonded to each other to form a cyclic structure. Here, the cyclic structure formed by combining R _N21 and X ₂₁ is preferably a 5- to 7-membered non-aromatic carbocyclic or heterocyclic ring condensed with a benzene ring. , Tetrahydroquinoline ring, tetrahydroquinoxaline ring, indoline ring, 2,3-dihydro-5,6-benzo-1,4-thiazine ring and the like. Preferred are a tetrahydroquinoline ring, a tetrahydroquinoxaline ring and an indoline ring.

In the general formula (3), when R _N31 represents a group other than an aryl group, R _a and R _b are bonded to each other to form an aromatic ring. Here, the aromatic ring is an aryl group (for example, phenyl group, naphthyl group) and an aromatic heterocyclic group (for example, pyridine ring group, pyrrole ring group, quinoline ring group, indole ring group, etc.), and an aryl group is preferable. The aromatic ring group may have an arbitrary substituent.
In the general formula (3), R _a and R _b are preferably bonded to each other to form an aromatic ring (particularly a phenyl group).

Formula (3) in R ₃₂ is preferably a hydrogen atom, an alkyl group, an aryl group, hydroxy group, an alkoxy group, a mercapto group, and the like amino group, wherein when R ₃₂ represents a hydroxy group, R ₃₃ at the same time A case of representing an “electron withdrawing group” is also a preferred example. Here, the “electron withdrawing group” is the same as described above, and an acyl group, an alkoxycarbonyl group, a carbamoyl group, and a cyano group are preferable.

Next, the type 2 compound will be described.
In the type 2 compound, “bond cleavage reaction” means the cleavage of a bond between carbon-carbon, carbon-silicon, carbon-hydrogen, carbon-boron, carbon-tin, and carbon-germanium, and carbon-hydrogen. This may be accompanied by cleavage of the bond.

  The type 2 compound is a compound having two or more (preferably 2 to 6, more preferably 2 to 4) adsorptive groups to silver halide in the molecule. More preferred is a compound having a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as an adsorptive group. The number of adsorptive groups is preferably 2-6, more preferably 2-4. The adsorptive group will be described later.

  A preferable compound among the compounds of type 2 is represented by the general formula (C).

Here, the compound represented by the general formula (C) has a structure in which, after the reducing group represented by RED ₂ is oxidized by one electron, L ₂ is spontaneously released by a bond cleavage reaction. It is a compound that can emit one electron.

In the general formula (C), RED ₂ represents a group having the same meaning as RED _{12 in the} general formula (B), and its preferred range is also the same. L ₂ represents a group having the same meaning as described for L ₁₁ in the general formula (A), and its preferred range is also the same. When L ₂ represents a silyl group, the compound is a compound having a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as an adsorptive group in the molecule. R ₂₁ and R ₂₂ each represents a hydrogen atom or a substituent, and these are groups having the same meaning as R _{112 in} formula (A), and the preferred range thereof is also the same. RED ₂ and R ₂₁ may be bonded to each other to form a ring structure.

  The ring structure formed here is a 5-membered to 7-membered monocyclic or condensed, non-aromatic carbocycle or heterocycle, which may have a substituent. However, the ring structure is not a ring structure corresponding to a tetrahydro, hexahydro or octahydro form of an aromatic ring or an aromatic heterocycle. The ring structure is preferably a ring structure corresponding to a dihydro form of an aromatic ring or an aromatic heterocycle, and specific examples thereof include, for example, 2-pyrroline ring, 2-imidazoline ring, 2-thiazoline ring, 1,2- Dihydropyridine ring, 1,4-dihydropyridine ring, indoline ring, benzimidazoline ring, benzothiazoline ring, benzoxazoline ring, 2,3-dihydrobenzothiophene ring, 2,3-dihydrobenzofuran ring, benzo-α-pyran ring, 1 , 2-dihydroquinoline ring, 1,2-dihydroquinazoline ring, 1,2-dihydroquinoxaline ring and the like, preferably 2-imidazoline ring, 2-thiazoline ring, indoline ring, benzoimidazoline ring, benzothiazoline ring, Benzoxazoline ring, 1,2-dihydropyridine ring, 1,2-dihydroquinolyl Ring, 1,2-dihydro-quinazoline ring, and the like 1,2-dihydro-quinoxaline ring, indoline ring, benzimidazoline ring, a benzothiazoline ring, 1,2-dihydroquinoline ring is more preferable, indoline ring is particularly preferred.

Next, the compound of type 3 will be described.
In the type 3 compound, “bond formation process” means formation of an interatomic bond such as carbon-carbon, carbon-nitrogen, carbon-sulfur, carbon-oxygen and the like.

  The compound of type 3 is preferably a reactive group site (carbon-carbon double bond site, carbon-carbon triple bond site, fragrance) in which a one-electron oxidant formed by one-electron oxidation coexists in the molecule. And a non-aromatic heterocyclic group part of a benzo-condensed ring) to form a bond and then emit one electron or more electrons.

More specifically, a type 3 compound has a one-electron oxidant formed by one-electron oxidation (a cation radical species or a neutral radical species produced by elimination of a proton therefrom) in the same molecule. It reacts with the coexisting reactive group, forms a bond, and generates a radical species having a new ring structure in the molecule. This radical species has a feature that electrons of the second electron are emitted directly or with elimination of protons.
And in some Type 3 compounds, the two-electron oxidant so produced is then subjected to a hydrolysis reaction in some cases, and in some cases tautomerization with direct proton transfer. There is a case in which one or more electrons, usually two or more electrons are emitted from the oxidization reaction. Alternatively, those having the ability to emit one or more electrons, usually two or more electrons, directly from a two-electron oxidant without going through such a tautomerization reaction are also included.

  The compound of type 3 is preferably represented by the general formula (D).

In the general formula (D), RED ₃ represents a reducing group that can be oxidized by one electron, Y ₃ represents a reactive group site that reacts after RED ₃ is oxidized by one electron, and specifically, a carbon-carbon double layer. It represents an organic group containing a binding site, a carbon-carbon triple bond site, an aromatic group site, or a non-aromatic heterocyclic group site of a benzo-fused ring. L ₃ represents a linking group that links RED ₃ and Y ₃ .

RED ₃ represents a group having the same meaning as RED _{12 in} formula (B), and preferably an arylamino group, a heterocyclic amino group, an aryloxy group, an arylthio group, an aryl group, an aromatic or non-aromatic heterocyclic group ( Particularly preferred is a nitrogen-containing heterocyclic group), and more preferred is an arylamino group, a heterocyclic amino group, an aryl group, an aromatic or non-aromatic heterocyclic group, and among these heterocyclic groups, tetrahydroquinoline is preferred. Ring group, tetrahydroquinoxaline ring group, tetrahydroquinazoline ring group, indoline ring group, indole ring group, carbazole ring group, phenoxazine ring group, phenothiazine ring group, benzothiazoline ring group, pyrrole ring group, imidazole ring group, thiazole ring group , Benzimidazole ring group, benzimidazoline ring group, benzothiazoline ring group, 3,4 Such methylenedioxyphenyl-1-yl group are preferable.
RED ₃ is particularly preferably an arylamino group (particularly an anilino group), an aryl group (particularly a phenyl group), or an aromatic or non-aromatic heterocyclic group.

Here, when RED ₃ represents an aryl group, the aryl group preferably has at least one “electron-donating group”. The “electron donating group” is the same as described above.

When RED ₃ represents an aryl group, the substituent of the aryl group is more preferably an alkylamino group, a hydroxy group, an alkoxy group, a mercapto group, a sulfonamide group, an active methine group, or a non-aromatic nitrogen-containing group substituted with a nitrogen atom A heterocyclic group, more preferably an alkylamino group, a hydroxy group, an active methine group, and a non-aromatic nitrogen-containing heterocyclic group substituted with a nitrogen atom, most preferably an alkylamino group and a non-aromatic group substituted with a nitrogen atom Group nitrogen-containing heterocyclic group.

When the organic group (for example, vinyl group) containing a carbon-carbon double bond site represented by Y ₃ has a substituent, the substituent is preferably an alkyl group, phenyl group, acyl group, cyano group, alkoxycarbonyl. A group, a carbamoyl group, an electron donating group, etc., and an electron donating group is preferably an alkoxy group, a hydroxy group (which may be protected with a silyl group, for example, a trimethylsilyloxy group, a t-butyldimethylsilyloxy group). , Triphenylsilyloxy group, triethylsilyloxy group, phenyldimethylsilyloxy group, etc.), amino group, alkylamino group, arylamino group, sulfonamide group, active methine group, mercapto group, alkylthio group, and these A phenyl group having an electron-donating group as a substituent.

Note here carbon - when the organic group having a hydroxy group as a substituent containing a carbon double bond moiety, Y ₃ is right partial _{structure:> C 1 = C 2 (} -OH) - but it will include this May be tautomerized to form the partial structure shown on the right:> C ₁ H—C ₂ (═O) —. Further, in this case, it is also preferable that the substituent substituted on the C ₁ carbon is an electron-withdrawing group. In this case, Y ₃ has a partial structure of “active methylene group” or “active methine group”. Become. The electron withdrawing group that can give such a partial structure of an active methylene group or active methine group is the same as that described in the description of the above “active methine group”.

When the organic group (for example, ethynyl group) containing a carbon-carbon triple bond site represented by Y ₃ has a substituent, the substituent includes an alkyl group, a phenyl group, an alkoxycarbonyl group, a carbamoyl group, and an electron donating group. Etc. are preferable.

When Y ₃ represents an organic group containing an aromatic group, it is preferably an aryl group having an electron donating group as a substituent (particularly a phenyl group) or an indole ring group as an aromatic group, and an electron donating group here. The group is preferably a hydroxy group (which may be protected with a silyl group), an alkoxy group, an amino group, an alkylamino group, an active methine group, a sulfonamide group or a mercapto group.

When Y ₃ represents an organic group containing a non-aromatic heterocyclic group part of a benzo-fused ring, the non-aromatic heterocyclic group of the benzo-fused ring preferably contains an aniline structure as a partial structure, for example, an indoline ring Group, 1,2,3,4-tetrahydroquinoline ring group, 1,2,3,4-tetrahydroquinoxaline ring group, 4-quinolone ring group and the like.

The reactive group represented by Y ₃ is more preferably an organic group containing a carbon-carbon double bond site, an aromatic group site, or a benzo-fused non-aromatic heterocyclic group. More preferred are a carbon-carbon double bond site, a phenyl group having an electron donating group as a substituent, an indole ring group, and a benzo-fused non-aromatic heterocyclic group having an aniline structure as a partial structure. Here, the carbon-carbon double bond site preferably has at least one electron donating group as a substituent.

When the reactive group represented by Y ₃ has the same partial structure as the reducing group represented by RED ₃ as a result of selection from the range described so far, it is also represented by the general formula (D). This is a preferred example of the compound.

L ₃ represents a linking group that links RED ₃ and Y ₃ , specifically, a single bond, an alkylene group, an arylene group, a heterocyclic group, —O—, —S—, —NR _N —, —C (= O) -, - SO 2 -, - SO -, - represents a single respective group, or a group comprising a combination of these groups - P (= O). Here, _RN represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. The linking group represented by L ₃ may have an arbitrary substituent. The linking group represented by L ₃ can be linked at any position of the groups represented by RED ₃ and Y ₃ in such a manner as to substitute for any one hydrogen atom.
Preferred examples of L ₃ include a single bond, an alkylene group (particularly a methylene group, an ethylene group, a propylene group), an arylene group (particularly a phenylene group), a —C (═O) — group, an —O— group, —NH—. And a divalent linking group comprising a group, -N (alkyl group)-group, and a combination of these groups.

Group represented by L _3, a cation radical species RED ₃ generated by oxidation (X ⁺ ·), or from which a radical species generated with elimination of protons (X ·), tables in Y ₃ When a reactive group reacts to form a bond, it is preferable that an atomic group related to this can form a _3- to 7-membered cyclic structure including L ₃ . For this purpose, the radical species (X ⁺ .or X.), the reactive group represented by Y, and L are preferably connected by 3 to 7 atomic groups.

Next, the type 4 compound will be described.
A compound of type 4 is a compound having a ring structure substituted with a reducing group, and after the reducing group is oxidized by one electron, one or more electrons are emitted along with the ring structure cleavage reaction. Compound. The ring structure cleavage reaction referred to here means one having the following form.

  In the formula, compound a represents a type 4 compound. In compound a, D represents a reducing group, and X and Y represent atoms forming a bond that is cleaved after one-electron oxidation in the ring structure. First, one-electron oxidation of the compound a generates a one-electron oxidant b. From this, the single bond of XX becomes a double bond, and at the same time, the bond of XY is cleaved to produce a ring-opened product c. Alternatively, a radical intermediate d may be generated from the one-electron oxidant b with proton desorption, and a ring-opening body e may be similarly generated therefrom. These compounds are characterized in that one or more electrons are subsequently released from the ring-opened product c or e thus produced.

  The ring structure possessed by the type 4 compound is a 3- to 7-membered carbocyclic or heterocyclic ring, and represents a monocyclic or condensed, saturated or unsaturated non-aromatic ring. A saturated ring structure is preferable, and a 3-membered ring or 4-membered ring is more preferable. Preferred examples of the ring structure include a cyclopropane ring, a cyclobutane ring, an oxirane ring, an oxetane ring, an aziridine ring, an azetidine ring, an episulfide ring, and a thietane ring. More preferred are a cyclopropane ring, a cyclobutane ring, an oxirane ring, an oxetane ring and an azetidine ring, and particularly preferred are a cyclopropane ring, a cyclobutane ring and an azetidine ring. The ring structure may have an arbitrary substituent.

  The compound of type 4 is preferably represented by the general formula (E) or (F).

In the general formula (E) and the general formula (F), RED ₄₁ and RED ₄₂ each represent a group having the same meaning as RED _{12 in the} general formula (B), and preferred ranges thereof are also the same. R _{40 to} R ₄₄ and R _{45 to} R ₄₉ each represent a hydrogen atom or a substituent. Z ₄₂ in formula (F) _{is, -CR 420 R 421 -, -} NR 423 -, or an -O-. Here, R ₄₂₀ and R ₄₂₁ each represent a hydrogen atom or a substituent, and R ₄₂₃ represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

In General Formula (E) and General Formula (F), R ₄₀ and R ₄₅ preferably represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group, and more preferably a hydrogen atom, an alkyl group, or an aryl group. R _{41 to} R ₄₄ and R _{46 to} R ₄₉ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an arylthio group, an alkylthio group, an acylamino group, or a sulfonamide group, more preferably a hydrogen atom. , An alkyl group, an aryl group, and a heterocyclic group.

R _{41 to} R ₄₄ are preferably a case where at least one of them is a donor group and a case where R ₄₁ and R ₄₂ , or R ₄₃ and R ₄₄ are both electron withdrawing groups. More preferably, at least one of R _{41 to} R ₄₄ is a donor group. More preferably, at least one of R _{41 to} R ₄₄ is a donor group, and a group that is not a donor group among R _{41 to} R ₄₄ is a hydrogen atom or an alkyl group.

  The donor group mentioned here is an “electron-donating group” or an aryl group substituted with at least one “electron-donating group”. The donor group is preferably an alkylamino group, an arylamino group, a heterocyclic amino group, a 5-membered monocyclic or condensed ring electron-rich aromatic heterocyclic group containing at least one nitrogen atom in the ring, nitrogen A non-aromatic nitrogen-containing heterocyclic group substituted with an atom or a phenyl group substituted with at least one electron-donating group is used. More preferably, an alkylamino group, an arylamino group, a 5-membered monocyclic or condensed ring-excessive aromatic heterocyclic group containing at least one nitrogen atom in the ring (an indole ring, a pyrrole ring, a carbazole ring, etc.) ), A phenyl group substituted with an electron donating group (such as a phenyl group substituted with three or more alkoxy groups, a phenyl group substituted with a hydroxy group, an alkylamino group, or an arylamino group). Particularly preferably, an arylamino group, a 5-membered monocyclic or condensed ring-containing electron-rich aromatic heterocyclic group (particularly a 3-indolyl group) or an electron-donating group containing at least one nitrogen atom in the ring is substituted. A phenyl group (particularly a phenyl group substituted with a trialkoxyphenyl group, an alkylamino group or an arylamino group) is used.

Z ₄₂ is preferably —CR ₄₂₀ R ₄₂₁ — or —NR ₄₂₃ —, more preferably —NR ₄₂₃ —. R ₄₂₀ and R ₄₂₁ are preferably a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an acylamino group, or a sulfoneamino group, and more preferably a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. R ₄₂₃ preferably represents a hydrogen atom, an alkyl group, an aryl group or an aromatic heterocyclic group, more preferably a hydrogen atom, an alkyl group or an aryl group.

When each group of R _{40 to} R ₄₉ and R ₄₂₀ , R ₄₂₁ and R ₄₂₃ is a substituent, the total number of carbon atoms is preferably 40 or less, more preferably 30 or less, and particularly preferably The total carbon number is 15 or less. In addition, these substituents may be bonded to each other or may be bonded to other sites (RED ₄₁ , RED ₄₂ or Z ₄₂ ) in the molecule to form a ring.

  In the compounds of types 1 to 4 in the present invention, the adsorptive group to silver halide is a group that directly adsorbs to silver halide, or a group that promotes adsorption to silver halide. Specifically, A heterocyclic group containing at least one atom selected from a mercapto group (or a salt thereof), a thione group (—C (═S) —), a nitrogen atom, a sulfur atom, a selenium atom and a tellurium atom, a sulfide group, and a cationic group Or an ethynyl group. However, the type 2 compound in the present invention does not contain a sulfide group as an adsorptive group.

The mercapto group (or salt thereof) as the adsorptive group means the mercapto group (or salt thereof) itself, and more preferably a heterocyclic group or aryl group substituted with at least one mercapto group (or salt thereof). Or represents an alkyl group. Here, the heterocyclic group is a 5-membered to 7-membered monocyclic or condensed aromatic or non-aromatic heterocyclic group such as an imidazole ring group, a thiazole ring group, an oxazole ring group, or a benzimidazole ring group. , Benzthiazole ring group, benzoxazole ring group, triazole ring group, thiadiazole ring group, oxadiazole ring group, tetrazole ring group, purine ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, pyrimidine ring group, triazine A cyclic group etc. are mentioned. Further, it may be a heterocyclic group containing a quaternized nitrogen atom. In this case, the substituted mercapto group may be dissociated into a meso ion. Examples of such a heterocyclic group include an imidazolium ring group, Examples include a pyrazolium ring group, a thiazolium ring group, a triazolium ring group, a tetrazolium ring group, a thiadiazolium ring group, a pyridinium ring group, a pyrimidinium ring group, and a triazinium ring group. Triazolium-3-thiolate ring group) is preferable. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkyl group include linear, branched or cyclic alkyl groups having 1 to 30 carbon atoms. When the mercapto group forms a salt, the counter ion includes a cation such as alkali metal, alkaline earth metal, heavy metal (Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ag ⁺ , Zn ^2+, etc.), ammonium ion Examples thereof include a heterocyclic group containing a quaternized nitrogen atom, and a phosphonium ion.

  Further, the mercapto group as the adsorptive group may be tautomerized into a thione group, specifically, a thioamide group (here, —C (═S) —NH— group), and the thioamide group. A group having a partial structure of, ie, a chain or cyclic thioamide group, a thioureido group, a thiourethane group, or a dithiocarbamate group. Examples of cyclic groups include thiazolidine-2-thione group, oxazolidine-2-thione group, 2-thiohydantoin group, rhodanine group, isorhodanine group, thiobarbituric acid group, 2-thioxo-oxazolidine-4-one group Is mentioned.

  The thione group as an adsorptive group cannot be tautomerized to a mercapto group (including a hydrogen atom at the α-position of the thione group), including the case where the mercapto group described above is tautomerized into a thione group. A chain or cyclic thioamide group, thioureido group, thiourethane group, or dithiocarbamate group is also included.

  A heterocyclic group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom and a tellurium atom as the adsorptive group is a partial structure of a heterocyclic ring, which can form an imino silver (> NAg) A nitrogen-containing heterocyclic group, or a heterocyclic ring having a —S— group, a —Se— group, a —Te— group or a ═N— group as a partial structure of the heterocyclic ring, which can coordinate to a silver ion by a coordination bond Group, the former examples include benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group, purine group, and the latter examples include thiophene group, thiazole group, oxazole group, Benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, triazine group, selenoazole group, benz Renoazoru group, tellurium azole group, such as benz tellurium azole group. The former is preferred.

  The sulfide group as the adsorptive group includes all groups having a partial structure of —S—, but preferably an alkyl (or alkylene) -S-alkyl (or alkylene), aryl (or arylene) -S-alkyl ( Or a group having a partial structure of aryl) or aryl (or arylene) -S-aryl (or arylene). Furthermore, these sulfide groups may form a cyclic structure or may be an -S-S- group. Specific examples in the case of forming a cyclic structure include a thiolane ring, a 1,3-dithiolane ring or a 1,2-dithiolane ring, a thiane ring, a dithiane ring, a tetrahydro-1,4-thiazine ring (thiomorpholine ring) and the like. Groups. Particularly preferred as the sulfide group is a group having a partial structure of alkyl (or alkylene) -S-alkyl (or alkylene).

  The cationic group as the adsorptive group means a group containing a quaternized nitrogen atom, specifically, an ammonio group or a group containing a nitrogen-containing heterocyclic group containing a quaternized nitrogen atom. . However, the cationic group does not become a part of an atomic group forming a dye structure (for example, a cyanine chromophore). Here, the ammonio group is a trialkylammonio group, a dialkylarylammonio group, an alkyldiarylammonio group or the like, and examples thereof include a benzyldimethylammonio group, a trihexylammonio group, and a phenyldiethylammonio group. Examples of the nitrogen-containing heterocyclic group containing a quaternized nitrogen atom include a pyridinio group, a quinolinio group, an isoquinolinio group, an imidazolio group, and the like. A pyridinio group and an imidazolio group are preferable, and a pyridinio group is particularly preferable. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent, but in the case of a pyridinio group and an imidazolio group, the substituent is preferably an alkyl group, an aryl group, or an acylamino group. , A chloro atom, an alkoxycarbonyl group, a carbamoyl group, and the like. In the case of a pyridinio group, a phenyl group is particularly preferable as a substituent.

An ethynyl group as an adsorptive group means a —C≡CH group, and a hydrogen atom may be substituted.
The above adsorptive group may have an arbitrary substituent.

  Specific examples of the adsorptive group further include those described in pages 4 to 7 of JP-A No. 11-95355.

  Preferred as the adsorptive group in the present invention is a mercapto-substituted nitrogen-containing heterocyclic group (for example, 2-mercaptothiadiazole group, 3-mercapto-1,2,4-triazole group, 5-mercaptotetrazole group, 2-mercapto-1). , 3,4-oxadiazole group, 2-mercaptobenzoxazole group, 2-mercaptobenzthiazole group, 1,5-dimethyl-1,2,4-triazolium-3-thiolate group, etc.) or imino silver (> A nitrogen-containing heterocyclic group (for example, a benzotriazole group, a benzimidazole group, an indazole group, etc.) having a —NH— group that can form NAg) as a partial structure of the heterocyclic ring. Particularly preferred are a 5-mercaptotetrazole group, a 3-mercapto-1,2,4-triazole group, and a benzotriazole group, and most preferred are a 3-mercapto-1,2,4-triazole group, and 5 -Mercaptotetrazole group.

  Among these compounds, compounds having two or more mercapto groups as partial structures in the molecule are also particularly preferable compounds. Here, the mercapto group (—SH) may be a thione group if it can be tautomerized. Examples of such compounds include the above-described adsorptive groups having a mercapto group or thione group as a partial structure (for example, a ring-forming thioamide group, an alkyl mercapto group, an aryl mercapto group, a heterocyclic mercapto group, etc.) Or a compound having two or more mercapto groups or thione groups as a partial structure (for example, a dimercapto-substituted nitrogen-containing heterocyclic group). You may have one or more.

  Examples of the adsorptive group having two or more mercapto groups as a partial structure (such as a dimercapto-substituted nitrogen-containing heterocyclic group) include 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3, 5-dimercapto-1,2,4-triazole group, 2,5-dimercapto-1,3-thiazole group, 2,5-dimercapto-1,3-oxazole group, 2,7-dimercapto-5-methyl-s -Triazolo (1,5-A) -pyrimidine, 2,6,8-trimercaptopurine, 6,8-dimercaptopurine, 3,5,7-trimercapto-s-triazolotriazine, 4,6-di And mercaptopyrazolopyrimidine, 2,5-dimercaptoimidazole, etc., 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3, - dimercapto-1,2,4-triazole group are particularly preferred.

The adsorptive group may be substituted anywhere in the general formulas (A) to (F) and the general formulas (1) to (3), but in the general formulas (A) to (D), RED ₁₁ , RED ₁₂ , RED ₂ and RED ₃ are represented by RED ₄₁ , R ₄₁ , RED ₄₂ and R _{46 to} R ₄₈ in the general formulas (E) and (F), and R ₁ and R ₂ in the general formulas (1) to (3). , R ₁₁ , R ₁₂ , R ₃₁ , L ₁ , L ₂₁ , and L ₃₁ are preferably substituted at any position, and in all of the general formulas (A) to (F), RED _{11 to} RED ₄₂ are substituted. More preferably it is substituted.

The partial structure of the spectral sensitizing dye is a group containing a chromophore of the spectral sensitizing dye, and is a residue obtained by removing any hydrogen atom or substituent from the spectral sensitizing dye compound. The partial structure of the spectral sensitizing dye may be substituted anywhere in the general formulas (A) to (F) and the general formulas (1) to (3), but in the general formulas (A) to (D), RED ₁₁ , RED ₁₂ , RED ₂ , RED ₃ , RED ₄₁ , R ₄₁ , RED ₄₂ , R _{46 to} R ₄₈ in general formulas (E) and (F), and R in general formulas (1) to (3) ₁ , R ₂ , R ₁₁ , R ₁₂ , R ₃₁ , L ₁ , L ₂₁ , and L ₃₁ are preferably substituted at any position except RED _{11 in} all of the general formulas (A) to (F). it is more preferably substituted in ~RED _42. Preferred spectral sensitizing dyes are spectral sensitizing dyes typically used in color sensitization techniques such as cyanine dyes, complex cyanine dyes, merocyanine dyes, complex merocyanine dyes, homopolar cyanine dyes, Contains styryl dyes and hemicyanine dyes. Exemplary spectral sensitizing dyes are disclosed in Research Disclosure, Item 36544, September 1994. Research Disclosure or F.I. M.M. One of ordinary skill in the art can synthesize these dyes by the procedure described in Hammer's The Cyanines and Related Compounds (Interscience Publishers, New yprk, 1964). Furthermore, all the dyes described in JP-A-11-95355 (US Pat. No. 6,054,260), pages 7 to 14 are applied as they are.

  The compounds of types 1 to 4 in the present invention preferably have a total carbon number of 10 to 60. More preferably, it is 15-50, More preferably, it is 18-40, Most preferably, it is 18-30.

  The compounds of types 1 to 4 in the present invention are subjected to one-electron oxidation triggered by the exposure of the silver halide photographic light-sensitive material using the compound, and after the subsequent reaction, one more electron or two or more electrons depending on the type Electrons are emitted and oxidized, and the oxidation potential of the first electron is preferably about 1.4 V or less, and more preferably 1.0 V or less. This oxidation potential is preferably higher than 0V, more preferably higher than 0.3V. Accordingly, the oxidation potential is preferably in the range of about 0 to about 1.4V, more preferably about 0.3 to about 1.0V.

  Here, the oxidation potential can be measured by a cyclic voltammetry technique. Specifically, a sample is dissolved in a solution of acetonitrile: water (including 0.1 M lithium perchlorate) = 80%: 20% (volume%). After bubbling nitrogen gas for 10 minutes, a glassy carbon disk was used as the working electrode, a platinum wire was used as the counter electrode, and a calomel electrode (SCE) was used as the reference electrode at 25 ° C. and 0.1 V / Measured at a potential scanning speed of seconds. The oxidation potential versus SCE is taken at the peak potential of the cyclic voltammetry wave.

  In the case where the compounds of types 1 to 4 in the present invention are one-electron oxidized and further emit one electron after the subsequent reaction, the subsequent oxidation potential is preferably −0.5 V to −2 V. More preferably, it is -0.7V--2V, More preferably, it is -0.9V--1.6V.

  In the case where the compound of type 1 to 4 in the present invention is a compound which is oxidized by one electron and then emits two or more electrons after the subsequent reaction and is oxidized, there is no particular limitation on the oxidation potential of this latter stage. Absent. This is because the oxidation potential of the second electron and the oxidation potential of the third and subsequent electrons cannot be clearly distinguished, and it is often difficult to accurately measure and distinguish these actually.

Next, the compound of type 5 will be described.
A compound of type 5 is represented by XY, where X represents a reducing group, Y represents a leaving group, and a one-electron oxidant produced by one-electron oxidation of the reducing group represented by X is , A compound capable of releasing Y by releasing Y along with the subsequent cleavage reaction of the XY bond and releasing another electron therefrom. The reaction when such a type 5 compound is oxidized can be represented by the following formula.

  The compound of type 5 preferably has an oxidation potential of 0 to 1.4V, more preferably 0.3V to 1.0V. The oxidation potential of the radical X · generated in the above reaction formula is preferably −0.7 V to −2.0 V, more preferably −0.9 V to −1.6 V.

  The compound of type 5 is preferably represented by the general formula (G).

In General Formula (G), RED ₀ represents a reducing group, L ₀ represents a leaving group, and R ₀ and R ₀₀ represent a hydrogen atom or a substituent. RED ₀ and R ₀ , and R ₀ and R ₀₀ may be bonded to each other to form a ring structure. RED ₀ represents a group having the same meaning as RED _{2 in} formula (C), and its preferred range is also the same. R ₀ and R ₀₀ are groups having the same meaning as R ₂₁ and R _{22 in} formula (C), and their preferred ranges are also the same. However, R ₀ and R ₀₀ do not represent a group having the same meaning as L ₀ except for a hydrogen atom. RED ₀ and R ₀ may be bonded to each other to form a ring structure. As an example of the ring structure, RED ₂ and R _{21 in} formula (C) are linked to form a ring structure. The same example as the case is mentioned, The preferable range is also the same. Examples of the ring structure formed by combining R ₀ and R ₀₀ with each other include a cyclopentane ring and a tetrahydrofuran ring. In the general formula (G), L ₀ is a group having the same meaning as L _{2 in the} general formula (C), and the preferred range thereof is also the same.

The compound represented by the general formula (G) preferably has an adsorbing group to silver halide or a partial structure of a spectral sensitizing dye in the molecule, but L ₀ is a group other than a silyl group. When expressed, it does not have two or more adsorptive groups in the molecule at the same time. However, here, the sulfide group as the adsorptive group may have two or more, regardless of L ₀ .

Examples of the adsorptive group to the silver halide which the compound represented by the general formula (G) has are the same as the adsorptive groups which the compounds of types 1 to 4 in the present invention may have. In addition, all those described as “silver halide adsorbing groups” on pages 4 to 7 of JP-A No. 11-95355 can be mentioned, and preferred ranges are also the same.
The partial structure of the spectral sensitizing dye that the compound represented by the general formula (G) may have is the partial structure of the spectral sensitizing dye that the compounds of types 1 to 4 in the present invention may have. However, at the same time, all those described as “light-absorbing groups” on pages 7 to 14 of JP-A-11-95355 can be mentioned, and the preferred ranges are also the same.

  Although the specific example of the compound of the types 1-5 in this invention is enumerated below, this invention is not limited to these.

  The compounds of types 1 to 4 in the present invention are described in detail in Japanese Patent Application No. 2002-192373, Japanese Patent Application No. 2002-188537, Japanese Patent Application No. 2002-188536, Japanese Patent Application No. 2001-272137, and Japanese Patent Application No. 2002-192374, respectively. Same as described compound. Specific examples of compounds described in these patent application specifications can also be given as specific examples of compounds of types 1 to 4 in the present invention. Moreover, the synthesis example of the type 1-4 compound in this invention is also the same as what was described in these patents.

  Specific examples of the compound of type 5 in the present invention are further described in JP-A-9-211769 (compounds PMT-1 to S-37 described in Table E and Table F on pages 28-32) and JP-A-9-211174. JP-A-11-95355 (compounds INV1-36), JP-T-2001-99696 (compounds 1-74, 80-87, 92-122), US Pat. No. 5,747,235, US Pat. No. 5,747, No. 236, European Patent No. 786692A1 (compounds INV1 to 35), European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051, etc. Examples of compounds referred to as “deprotonated electron donating sensitizers” are mentioned as they are.

  The compounds of types 1 to 5 in the present invention may be used at any time during the production process of the photothermographic material at the time of preparing the photosensitive silver halide emulsion. For example, at the time of photosensitive silver halide grain formation, desalting step, chemical sensitization, before coating. Moreover, it can also add in several steps in these processes. The addition position is preferably from the end of formation of the photosensitive silver halide grains to before the desalting step, at the time of chemical sensitization (immediately after the start of chemical sensitization to immediately after completion), and before coating, more preferably from the time of chemical sensitization Until before mixing with the non-photosensitive organic silver salt.

  The compounds of types 1 to 5 in the present invention are preferably added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. When the compound is dissolved in water, the compound having higher solubility when the pH is raised or lowered may be dissolved at a higher or lower pH and added.

The compounds of types 1 to 5 in the present invention are preferably used in an emulsion layer containing a photosensitive silver halide and a non-photosensitive organic silver salt, but the photosensitive silver halide and the non-photosensitive organic silver salt are used. It may be added to the protective layer and the intermediate layer together with the emulsion layer to be contained and diffused during coating. The addition timing of these compounds is preferably 1 × 10 ^{−9 to} 5 × 10 ⁻¹ mol, more preferably 1 × 10 ^{−8 to} 5 × 10, per mol of silver halide, regardless of before and after the sensitizing dye. ^-2 mol of silver halide emulsion layer.

10) A plurality of silver halides in combination The photosensitive silver halide emulsion in the light-sensitive material used in the present invention may be one kind or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions, Those having different crystal habits and different chemical sensitization conditions may be used in combination. The gradation can be adjusted by using a plurality of types of photosensitive silver halides having different sensitivities. Examples of these technologies include JP-A-57-119341, 53-106125, 47-3929, 48-55730, 46-5187, 50-73627, 57-150841 and the like. Can be mentioned. The sensitivity difference is preferably 0.2 log E or more for each emulsion.

11) Coating amount The amount of photosensitive silver halide added is preferably 0.03 to 0.6 g / m ² , expressed as the coating silver amount per 1 m ² of the light-sensitive material, and 0.05 to 0.4 g. further preferably / m ^2, and most preferably from 0.07~0.3g / m ^2, relative to the organic silver salt to 1 mole of the photosensitive silver halide is 0.01 mol or more 0. 5 mol or less is preferable, More preferably, it is 0.02 mol or more and 0.3 mol or less, More preferably, it is 0.03 mol or more and 0.2 mol or less.

12) Mixing of photosensitive silver halide and organic silver salt For the mixing method and mixing conditions of separately prepared photosensitive silver halide and organic silver salt, the silver halide grains and organic silver salt that were prepared respectively were stirred at high speed. Prepare organic silver salt by mixing with a silver mill, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc. However, there is no particular limitation as long as the effects of the present invention are sufficiently exhibited. Moreover, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a preferred method for adjusting photographic characteristics.

13) Mixing of silver halide into coating solution In the present invention, silver halide is preferably added to the image forming layer coating solution from 180 minutes before application, preferably from 60 minutes to 10 seconds before application. However, the mixing method and mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method using a static mixer described in Chapter 8 of Nienow's “Liquid Mixing Technology” (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

(binder)
Any polymer may be used as the binder of the image-forming layer in the present invention. Suitable binders are transparent or translucent and generally colorless, and are natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, and other films. Forming media such as gelatins, gums, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) , Poly (methyl methacrylic acid) s, poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, Poly (vinyl acetal) s (for example, poly (vinyl acetal) (Formal) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s , Poly (olefin) s, cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

  In the present invention, the glass transition temperature of the binder that can be used in combination with the layer containing the organic silver salt is preferably 0 ° C. or higher and 80 ° C. or lower (hereinafter sometimes referred to as a high Tg binder), and preferably 10 ° C. to 70 ° C. Is more preferable, and it is still more preferable that it is 15 degreeC or more and 60 degrees C or less.

  In this specification, Tg is the same as that described for the back surface protective layer.

  Two or more binders may be used in combination as required. Further, a glass transition temperature of 20 ° C. or higher and a glass transition temperature of less than 20 ° C. may be used in combination. When two or more types of polymers having different Tg are blended, the mass average Tg is preferably within the above range.

In the present invention, the organic silver salt-containing layer is preferably applied and dried using a coating solution in which 30% by mass or more of the solvent is water to form a film.
In the present invention, when the organic silver salt-containing layer is formed using a coating solution in which 30% by mass or more of the solvent is water and dried, the binder of the organic silver salt-containing layer is further an aqueous solvent ( When it is soluble or dispersible in an aqueous solvent), the performance is improved particularly when it is made of a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The most preferable form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and as such a preparation method, there is a method of performing purification treatment using a separation functional membrane after polymer synthesis.

  The aqueous solvent in which the polymer is soluble or dispersible here is a mixture of water or water and 70% by mass 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, cellosolvs such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

  In the case of a system in which the polymer is not dissolved thermodynamically and exists in a so-called dispersed state, the term aqueous solvent is used here.

The “equilibrium moisture content at 25 ° C. and 60% RH” is the following using the mass W1 of the polymer in a humidity-controlled equilibrium under an atmosphere of 25 ° C. and 60% RH and the mass W0 of the polymer in an absolutely dry state at 25 ° C. It can be expressed as
Equilibrium moisture content at 25 ° C. and 60% RH = {(W1−W0) / W0} × 100 (mass%)

  For the definition and measurement method of moisture content, for example, Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Society of Polymer Sciences, Jinshokan) can be referred to.

  The equilibrium water content at 25 ° C. and 60% RH of the binder polymer in the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass. % To 1% by mass is desirable.

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle diameter of the dispersed particles is 1 to 50000 nm, preferably 5 to 1000 nm, more preferably 10 to 500 nm, and still more preferably 50 to 200 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

  In the present invention, preferred embodiments of the polymer that can be dispersed in an aqueous solvent include acrylic polymers, poly (esters), rubbers (eg, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (acetic acid). Hydrophobic polymers such as vinyl), poly (vinylidene chloride) and poly (olefin) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer. These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable. A crosslinkable polymer latex is particularly preferably used.

<Specific examples of latex>
Specific examples of preferable polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

PP-1; Latex of -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000, Tg 61 ° C.)
PP-2; latex of -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
PP-3; Latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
PP-4; Latex of -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C.)
PP-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
PP-6; Latex (crosslinkable) of -St (70) -Bu (27) -IA (3)-
PP-7; Latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
PP-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
PP-9; Latex (crosslinkable) of -St (70) -Bu (25) -DVB (2) -AA (3)-
PP-10; latex of VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80000)
PP-11; Latex (molecular weight 67000) of -VDC (85) -MMA (5) -EA (5) -MAA (5)-
PP-12; latex of -Et (90) -MAA (10)-(molecular weight 12000)
PP-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130,000, Tg 43 ° C)
PP-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33000, Tg 47 ° C.)
PP-15; Latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
PP-16; latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)

  The abbreviations for 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 polymer latex described above is also commercially available, and the following polymers can be used. Examples of the acrylic polymer include Sebian A-4635, 4718, 4601 (manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 857 (manufactured by Nippon Zeon Co., Ltd.), poly ( Examples of esters) include, for example, poly (urethanes) such as FINETEX ES650, 611, 675, 850 (above made by Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (more made by Eastman Chemical). Examples of rubbers such as HYDRAN AP10, 20, 30, 40 (more from Dainippon Ink Chemical Co., Ltd.) include LACSTAR 7310K, 3307B, 4700H, 7132C (more from Dainippon Ink Chemical Co., Ltd.) Nipol Lx416, 410, 438C, 2507 (made by Nippon Zeon Co., Ltd.) However, examples of poly (vinyl chloride) include G351 and G576 (manufactured by Nippon Zeon Co., Ltd.), and examples of poly (vinylidene chloride) include L502 and L513 (manufactured by Asahi Kasei Kogyo Co., Ltd.). Examples of poly (olefin) s include Chemipearl S120, SA100 (manufactured by Mitsui Petrochemical Co., Ltd.).

  These polymer latexes may be used alone or in combination of two or more as required.

<Preferred latex>
As the polymer latex used in the present invention, a styrene-butadiene copolymer latex is particularly preferable. The mass ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably 40:60 to 95: 5. The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99% by mass. Moreover, it is preferable that the polymer latex in this invention contains 1-6 mass% of acrylic acid or methacrylic acid with respect to the sum of styrene and butadiene, More preferably, it contains 2-5 mass%. The polymer latex in the present invention preferably contains acrylic acid. The preferred molecular weight range is the same as described above.

  Examples of latexes of styrene-butadiene acid copolymer that are preferably used in the present invention include the above-mentioned P-3 to P-8,15, commercially available products LACSTAR-3307B, 7132C, Nipol Lx416, and the like.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose may be added to the organic silver salt-containing layer of the light-sensitive material of the present invention. The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder of the organic silver salt-containing layer.

  The organic silver salt-containing layer (that is, the image forming layer) in the present invention is preferably formed using a polymer latex. The amount of the binder in the organic silver salt-containing layer is such that the mass ratio of all binders / organic silver salt is 1/10 to 10/1, more preferably 1/3 to 5/1, and still more preferably 1/1 to 3/1. / 1 range.

  In addition, such an organic silver salt-containing layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide which is a photosensitive silver salt. The mass ratio of silver is 400-5, more preferably 200-10.

The total binder amount of the image forming layer in the present invention is preferably 0.2 g / m ^{2 to} 30 g / m ² , more preferably 1 g / m ^{2 to} 15 g / m ² , still more preferably 2 g / m ^{2 to} 10 g / m ^2. Range. In the image forming layer in the invention, a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added.

<Preferable solvent for coating solution>
In the present invention, the solvent of the organic silver salt-containing layer coating solution of the light-sensitive material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent of the coating solution is preferably 50% by mass or more, more preferably 70% by mass or more. Examples of preferred solvent compositions include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / Ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical values are mass%).

(Anti-fogging agent)
Antifoggants, stabilizers and stabilizer precursors that can be used in the present invention are disclosed in paragraph No. 0070 of JP-A No. 10-62899, page 20, line 57 to page 21, line 7 of European Patent Publication No. 0803764A1. Compounds described in JP-A-9-281737 and JP-A-9-329864, compounds described in US Pat. Nos. 6,083,681, 6,083,681, and European Patent 1048875 It is done. The antifoggant preferably used in the present invention is an organic halide, and examples thereof include those disclosed in the patents described in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021. In particular, an organic halogen compound represented by formula (P) in JP-A No. 2000-284399, an organic polyhalogen compound represented by formula (II) in JP-A No. 10-339934, JP-A No. 2001-31644 and JP-A No. 2001-31644 are disclosed. The organic polyhalogen compounds described in 2001-33911 are preferred.

1) Organic polyhalogen compound Hereinafter, preferred organic polyhalogen compounds in the present invention will be described in detail. A preferred polyhalogen compound in the present invention is a compound represented by the following general formula (H).
General formula (H) Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In the general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 or 1, Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron withdrawing group.
In general formula (H), Q is preferably an aryl group or a heterocyclic group.
In the general formula (H), when Q is a heterocyclic group, a nitrogen-containing heterocyclic group containing 1 to 2 nitrogen atoms is preferable, and a 2-pyridyl group and a 2-quinolyl group are particularly preferable.
In the general formula (H), when Q is an aryl group, Q preferably represents a phenyl group substituted with an electron-attracting group having a positive Hammett's substituent constant σp. For Hammett's substituent constants, see Journal of Medicinal Chemistry, 1973, Vol. 16, no. 11, 1207-1216 etc. can be referred to. Examples of such an electron withdrawing group include a halogen atom (fluorine atom (σp value: 0.06), chlorine atom (σp value: 0.23), bromine atom (σp value: 0.23), iodine atom. (Σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp value: 0.54)), Cyano group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0.72)), aliphatic / aryl Or a heterocyclic acyl group (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), alkynyl group (for example, C≡CH (σp value: 0.23)), aliphatic Aryl or heterocyclic oxycarbo Group (for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), Examples thereof include a sulfoxide group, a heterocyclic group, and a phosphoryl group. The σp value is preferably in the range of 0.2 to 2.0, more preferably in the range of 0.4 to 1.0. Particularly preferred as the electron withdrawing group is a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, or an alkylphosphoryl group, and among them, a carbamoyl group is most preferred.
X is preferably an electron-withdrawing group, more preferably a halogen atom, aliphatic / aryl or heterocyclic sulfonyl group, aliphatic / aryl or heterocyclic acyl group, aliphatic / aryl or heterocyclic oxycarbonyl group, A carbamoyl group and a sulfamoyl group, particularly preferably a halogen atom. Among the halogen atoms, a chlorine atom, a bromine atom and an iodine atom are preferable, a chlorine atom and a bromine atom are more preferable, and a bromine atom is particularly preferable.
Y preferably represents -C (= O) -, - SO- or -SO ₂ -; more preferably, -C (= O) -, - SO 2 - , and particularly preferably -SO ₂ - is a . n represents 0 or 1, and is preferably 1.

  Specific examples of the compound represented by formula (H) in the present invention are shown below.

Examples of preferable polyhalogen compounds in the present invention other than the above include compounds described in JP-A Nos. 2001-31644, 2001-56526, and 2001-209145.
The compound represented by the general formula (H) in the present invention is preferably used in the range of 10 ⁻⁴ mol to 1 mol, more preferably 10 ⁻³ per mol of the non-photosensitive silver salt of the image forming layer. It is preferably used in the range of mol to 0.5 mol, more preferably in the range of 1 × 10 ⁻² mol to 0.2 mol.
In the present invention, examples of the method for incorporating the antifoggant into the light-sensitive material include the methods described in the method for containing a reducing agent, and the organic polyhalogen compound is also preferably added as a solid fine particle dispersion.

2) Other antifoggants Other antifoggants include mercury (II) salts described in paragraph No. 0113 of JP-A No. 11-65021, benzoic acids described in paragraph No. 0114 of the same, salicylic acid derivatives disclosed in JP-A No. 2000-206642, A formalin scavenger compound represented by the formula (S) in JP-A-2000-221634, a triazine compound according to claim 9 in JP-A-11-352624, and a compound represented by the general formula (III) in JP-A-6-11791 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene and the like.

The photothermographic material in the invention may contain an azolium salt for the purpose of fog prevention. Examples of the azolium salt include compounds represented by general formula (XI) described in JP-A-59-193447, compounds described in JP-B-55-12581, and general formula (II) described in JP-A-60-153039. And the compounds represented. The azolium salt may be added to any part of the photosensitive material, but the addition layer is preferably added to the layer having the photosensitive layer, and more preferably to the organic silver salt-containing layer. The azolium salt may be added at any step in the coating solution preparation. When added to the organic silver salt-containing layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. To immediately before coating. The azolium salt may be added by any method such as powder, solution, fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent. In the present invention, the azolium salt may be added in any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

(Other additives)
1) Mercapto, disulfide, and thiones In the present invention, mercapto compounds and disulfide compounds are used for the purpose of controlling development by suppressing or promoting development, improving spectral sensitization efficiency, and improving storage stability before and after development. And thione compounds, paragraphs 0067 to 0069 of JP-A-10-62899, compounds represented by formula (I) of JP-A-10-186572, and specific examples thereof include paragraph numbers 0033 to 0052. , European Patent Publication No. 0803764A1, page 20, lines 36-56. Of these, mercapto-substituted heteroaromatic compounds described in JP-A-9-297367, JP-A-9-304875, JP-A-2001-100388, JP-A-2002-303954, JP-A-2002-303951, and the like are preferable. .

2) Toning agent In the photothermographic material of the invention, it is preferable to add a toning agent. For the toning agent, paragraph numbers 0054 to 0055 of JP-A-10-62899, page 21 to 23 of European Patent Publication No. 0803764A1. Line 48, described in JP-A No. 2000-356317 and JP-A No. 2000-187298, and in particular, phthalazinones (phthalazinone, phthalazinone derivatives or metal salts; for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone. 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, diammonium phthalate) , Sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride) Combinations: phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6-t-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthalazine And 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferable, and a combination of phthalazines and phthalic acids is particularly preferable. Among them, a particularly preferable combination is a combination of 6-isopropylphthalazine and phthalic acid or 4-methylphthalic acid.

3) Plasticizer and lubricant The plasticizer and lubricant that can be used in the image forming layer in the invention are described in paragraph No. 0117 of JP-A No. 11-65021. The slip agent is described in JP-A No. 11-84573, paragraph numbers 0061 to 0064 and Japanese Patent Application No. 11-106881, paragraph numbers 0049 to 0062.

4) Dye, Pigment The photosensitive layer in the invention has various dyes and pigments (for example, CI Pigment Blue 60, CI, etc.) from the viewpoints of color tone improvement, prevention of interference fringes during laser exposure, and prevention of irradiation. Pigment Blue 64, CI Pigment Blue 15: 6) can be used. These are described in detail in WO98 / 36322, JP-A-10-268465, JP-A-11-338098 and the like.

5) Super-high contrast agent For the formation of a super-high contrast image suitable for printing plate making, it is preferable to add a super-high contrast agent to the image forming layer. As for the ultra-high contrast agent and its addition method and addition amount, paragraph No. 0118 of JP-A No. 11-65021, paragraph Nos. 0136 to 0193 of JP-A No. 11-223898, Formula (H) of JP-A No. 2000-284399, Compounds of formulas (1) to (3), formulas (A) and (B), compounds of general formulas (III) to (V) described in Japanese Patent Application No. 11-91652 (specific compounds: 24), the contrast accelerator is described in paragraph No. 0102 of JP-A No. 11-65021 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

  In order to use formic acid or formate as a strong fogging substance, it is preferably contained in an amount of 5 mmol or less, more preferably 1 mmol or less per mol of silver on the side having an image forming layer containing photosensitive silver halide.

When the ultrahigh contrast agent is used in the photothermographic material of the invention, it is preferable to use an acid formed by hydrating diphosphorus pentoxide or a salt thereof in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametalin An acid (salt) etc. can be mentioned. Examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide particularly preferably include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate.
The amount of acid or salt thereof formed by hydration of diphosphorus pentoxide (the coating amount per 1 m ^{2 of} light-sensitive material) may be a desired amount according to the performance such as sensitivity and fog, but is 0.1 to 500 mg / m ² is preferable, and 0.5 to 100 mg / m ² is more preferable.
The reducing agent, hydrogen bonding compound, development accelerator and polyhalogen compound in the present invention are preferably used as a solid dispersion, and a preferred method for producing these solid dispersions is described in JP-A-2002-55405. .

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution in the present invention is preferably from 30 ° C. to 65 ° C., more preferably from 35 ° C. to less than 60 ° C., and more preferably from 35 ° C. to 55 ° C. Moreover, it is preferable that the temperature of the image forming layer coating liquid immediately after the addition of the polymer latex is maintained at 30 ° C. or higher and 65 ° C. or lower.

1-5. Surface Protective Layer The photothermographic material according to the invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer or a plurality of layers.
The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and JP-A No. 2000-171936.
As the binder for the surface protective layer in the present invention, gelatin is preferable, but polyvinyl alcohol (PVA) is preferably used or used in combination. As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), and the like can be used. Examples of PVA include those described in paragraph Nos. 0009 to 0020 of JP-A No. 2000-171936. Completely saponified PVA-105, partially saponified PVA-205, PVA-335, and modified polyvinyl alcohol MP- Preferred is 203 (trade name, manufactured by Kuraray Co., Ltd.). Preferably 0.3 to 4.0 g / m ² of polyvinyl alcohol coating amount as (per support 1 m ²⁾ is the protective layer (per one layer), 0.3 to 2.0 g / m ² is more preferable.

The total amount of binder (including water-soluble polymer and latex polymer) applied to the surface protective layer (per layer) is preferably 0.3 to 5.0 g / m ² , preferably 0.3 to ² per 1 m ² of the support. 0.0 g / m ² is more preferable.

1-6. Other Layer Configurations and Components In the present invention, in addition to each of the above layers, an intermediate layer provided between a plurality of image forming layers, between an image forming layer and a protective layer, or between an image forming layer and a support. A provided undercoat layer or the like can be provided. Further, additives such as matting agent, latex, surfactant and the like can be added to these layers.

(Matting agent)
In the present invention, it is preferable to add a matting agent for improving transportability. The matting agent is described in paragraph Nos. 0126 to 0127 of JP-A No. 11-65021. When the matting agent is indicated by the coating amount per the photosensitive material 1 m ^2, preferably from ^{1mg / m 2 ~400mg / m 2} , more preferably ^{5mg / m 2 ~300mg / m 2} .
In the present invention, the shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used. The average particle size is preferably 0.5 to 10 μm, more preferably 1.0 μm to 8.0 μm, and still more preferably 2.0 μm to 6.0 μm. The variation coefficient of the size distribution is preferably 50% or less, more preferably 40% or less, and still more preferably 30% or less. Here, the coefficient of variation is a value represented by (standard deviation of particle size) / (average value of particle size) × 100. It is also preferable to use two types of matting agents having a small variation coefficient and having an average particle size ratio larger than 3.
The matting degree of the image forming layer surface may be any as long as no stardust failure occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, particularly preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily determined by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.

  In the present invention, the matte degree of the back layer is preferably a Beck smoothness of 1200 seconds or less and 10 seconds or more, preferably 800 seconds or less and 20 seconds or more, and more preferably 500 seconds or less and 40 seconds or more.

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

(Membrane surface pH adjuster)
The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before heat development. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2. The film surface pH is preferably adjusted using an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or heat development.
In addition, it is also preferable to use ammonia in combination with a nonvolatile base such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. A method for measuring the film surface pH is described in paragraph No. 0123 of JP-A No. 2000-284399.

(Surfactant)
For surfactants applicable to the present invention, paragraph number 0132 of JP-A No. 11-65021, paragraph number 0133 for solvents, paragraph number 0134 for supports, paragraph number for antistatic or conductive layers No. 0135, a method for obtaining a color image, paragraph No. 0136 of the same publication, and a slip agent, paragraph Nos. 0061 to 0064 of JP-A No. 11-84573 and paragraph Nos. 0049 to 0062 of Japanese Patent Application No. 11-106881 are described.
In the present invention, it is preferable to use a fluorosurfactant. Specific examples of the fluorosurfactant include compounds described in JP-A Nos. 10-197985, 2000-19680, 2000-214554 and the like. Further, a polymeric fluorine-based surfactant described in JP-A-9-281636 is also preferably used. In the photothermographic material of the present invention, it is preferable to use a fluorosurfactant described in JP-A No. 2002-82411, Japanese Patent Application Nos. 2001-242357 and 2001-264110. In particular, the fluorosurfactants described in Japanese Patent Application Nos. 2001-242357 and 2001-264110 are preferable in terms of charge adjustment ability, stability of the coated surface, and smoothness when coating and production is performed with an aqueous coating solution. The fluorine-based surfactant described in Japanese Patent Application No. 2001-264110 is most preferable in that it has a high charge adjustment capability and requires a small amount of use.
In the present invention, the fluorosurfactant can be used on either the emulsion surface or the back surface, and is preferably used on both surfaces. Further, it is particularly preferable to use in combination with a conductive layer containing the above-described metal oxide. In this case, sufficient performance can be obtained even if the amount of the fluorosurfactant used on the surface having the conductive layer is reduced or removed.
The preferred amount of the fluorocarbon surfactant is emulsion surface, ranging back surface each ^{0.1mg / m 2 ~100mg / m 2} , more preferably 0.3mg / m ² ~30mg / m ² range, further preferably in the range of ^{1mg / m 2 ~10mg / m 2} . Especially, the fluorocarbon surfactant described in Japanese Patent Application No. 2001-264110 is effective, and preferably in the range of ^{0.01mg / m 2 ~10mg / m 2} , more in the range of 0.1mg / m ² ~5mg / m ² preferable.

In particular, in the present invention, it is preferable to contain a fluorine compound having a fluorinated alkyl group having 2 or more carbon atoms and 13 or less fluorine atoms.
The fluorine compound may have any structure as long as it has the fluorinated alkyl group (hereinafter, an alkyl group substituted with a fluorine atom is referred to as “Rf”). The fluorine compound may have at least one Rf and may have two or more.

Specific examples of Rf include the following groups, but are not limited thereto.
-C ₂ F ₅ group, -C ₃ F ₇ group, -C ₄ F ₉ groups, -C ₅ F ₁₁ group, -CH ₂ -C ₄ F ₉ groups, -C ₄ F ₈ -H group, -C ₂ H ₄ -C ₄ F _{9 groups, -C 4 H 8 -C 4 F} 9 _{group, -C 6 H 12 -C 4 F} 9 _{groups, -C 8 H 16 -C 4 F} 9 groups, -C ₄ H ₈ -C ₂ F _{5 group, -C 4 H 8 -C 3 F} 7 _{group, -C 4 H 8 -C 5 F} 11 _{group, -C 8 H 16 -C 2 F} 5 group, -C ₂ H ₄ -C ₄ F ₈ -H _{group, -C 4 H 8 -C 4 F} 8 -H _{group, -C 6 H 12 -C 4 F} 8 -H group _{-C 6 H 12 -C 2 F 4} -H group, -C ₈ H ₁₆ -C ₂ F ₄ -H _{group, -C 6 H 12 -C 4 F} 8 -CH 3 _{group, -C 2 H 4 -C 3 F} 7 _{group, -C 2 H 4 -C 5 F} 11 group , —C ₄ H ₈ —CF (CF ₃ ) ₂ group, —CH ₂ CF ₃ group, —C ₄ H ₈ —CH (C ₂ F ₅ ) ₂ group, —C ₄ H ₈ —CH (CF ₃ ) _{2 groups, -C 4 H 8 -C (CF} 3) 3 group, -CH ₂ -C ₄ F ₈ -H Group, —CH ₂ —C ₆ F ₁₂ —H group, —CH ₂ —C ₆ F ₁₃ group, —C ₂ H ₄ —C ₆ F ₁₃ group, —C ₄ H ₈ —C ₆ F ₁₃ group, —C ₆ H ₁₂ -C ₆ F _{13 group, -C 8 H 16 -C 6 F} 13 group.

  Rf has 13 or less fluorine atoms, preferably 12 or less, more preferably in the range of 3 to 11, and still more preferably in the range of 5 to 9. The number of carbon atoms is 2 or more, preferably 4 to 16, more preferably 5 to 12.

  Rf is not particularly limited as long as it has 2 or more carbon atoms and 13 or less fluorine atoms, but is preferably a group represented by the following general formula (A).

Formula (A)
-Rc-Re-W

The fluorine compound more preferably has two or more fluorinated alkyl groups represented by the general formula (A).
In the general formula (A), Rc represents an alkylene group having 1 to 4 carbon atoms, preferably in the range of 1 to 3 carbon atoms, more preferably in the range of 1 to 2. The alkylene group represented by Rc may be linear or branched.
Re represents a C 2-6 perfluoroalkylene group, preferably a C 2-4 perfluoroalkylene group. Here, the perfluoroalkylene group refers to an alkylene group in which all hydrogen atoms of the alkylene group are replaced with fluorine atoms. The perfluoroalkylene group may be linear or branched, and may have a cyclic structure.
W represents a hydrogen atom, a fluorine atom or an alkyl group, preferably a hydrogen atom or a fluorine atom. Particularly preferred is a fluorine atom.

The said fluorine compound can also have a cationic hydrophilic group.
The cationic hydrophilic group is a group that becomes a cation when dissolved in water. Specific examples include quaternary ammonium, alkyl pyridium, alkyl imidazolinium, and primary to tertiary aliphatic amines.
The cation is preferably an organic cationic substituent, and more preferably an organic cationic group containing a nitrogen or phosphorus atom. More preferably, it is a pyridinium cation or an ammonium cation.
The anion species forming the salt may be an inorganic anion or an organic anion. Preferred examples of the inorganic anion include iodo ion, bromine ion, and chlorine ion. Preferred examples of the organic anion include p-toluenesulfonate ion, benzenesulfonate ion, methanesulfonate ion, and trifluoromethanesulfonate ion. It is done.

  A preferred cationic fluorine compound in the present invention is represented by the following general formula (1).

In the formula, R ¹ and R ² each independently represents a substituted or unsubstituted alkyl group, and at least one of R ¹ and R ² is the above-mentioned fluorinated alkyl group (Rf). Preferred is when both R ¹ and R ² are Rf. R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or a substituent, X ¹ , X ² and Z each independently represent a divalent linking group or a single bond, and M ⁺ represents a cationic group. Represents a substituent. Y ⁻ represents a counter anion, but Y ⁻ may not be present when the charge is 0 in the molecule. m is 0 or 1.

In the general formula (1), when R ¹ and R ² each independently represents a substituted or unsubstituted alkyl group other than Rf, the alkyl group has 1 or more carbon atoms and is linear or branched. Either a chain or a ring may be used. Examples of the substituent include a halogen atom, an alkenyl group, an aryl group, an alkoxyl group, a halogen atom other than fluorine, a carboxylic acid ester group, a carbonamido group, a carbamoyl group, an oxycarbonyl group, and a phosphoric acid ester group.

When R ¹ or R ² represents an alkyl group other than Rf, that is, an alkyl group not substituted with a fluorine atom, the alkyl group is preferably a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, more preferably It is a substituted or unsubstituted alkyl group having 6 to 24 carbon atoms. Preferred examples of the unsubstituted alkyl group having 6 to 24 carbon atoms include n-hexyl group, n-heptyl group, n-octyl group, tert-octyl group, 2-ethylhexyl group, n-nonyl group, 1,1, 3-trimethylhexyl group, n-decyl group, n-dodecyl group, cetyl group, hexadecyl group, 2-hexyldecyl group, octadecyl group, eicosyl group, 2-octyldodecyl group, docosyl group, tetracosyl group, 2-decyltetra A decyl group, a tricosyl group, a cyclohexyl group, a cycloheptyl group, etc. are mentioned. Preferred examples of the alkyl group having 6 to 24 carbon atoms having a substituent include 2-hexenyl group, oleyl group, linoleyl group, linolenyl group, benzyl group, β-phenethyl group, 2-methoxyethyl group, 4-phenylbutyl group, 4-acetoxyethyl group, 6-phenoxyhexyl group, 12-phenyldodecyl group, 18-phenyloctadecyl group, 12- (p-chlorophenyl) dodecyl group, 2- (diphenyl phosphate) ethyl group, etc. Can be mentioned.

The alkyl group other than Rf independently represented by R ¹ and R ² is more preferably a substituted or unsubstituted alkyl group having 6 to 18 carbon atoms. Preferred examples of the unsubstituted alkyl group having 6 to 18 carbon atoms include n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, 1,1,3 -Trimethylhexyl group, n-decyl group, n-dodecyl group, cetyl group, hexadecyl group, 2-hexyldecyl group, octadecyl group, 4-tert-butylcyclohexyl group and the like can be mentioned. Preferable examples of the substituted alkyl group having 6 to 18 carbon atoms having a substituent include phenethyl group, 6-phenoxyhexyl group, 12-phenyldodecyl group, oleyl group, linoleyl group, and linolenyl group. .

The alkyl group other than Rf represented by R ¹ and R ² is particularly preferably an n-hexyl group, a cyclohexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, 1,1,3-trimethylhexyl group, n-decyl group, n-dodecyl group, cetyl group, hexadecyl group, 2-hexyldecyl group, octadecyl group, oleyl group, linoleyl group, linolenyl group, most preferably carbon It is a linear, cyclic or branched unsubstituted alkyl group of formula 8-16.

In the general formula (1), R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom or a substituent. Examples of the substituent include an alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, and isopropyl. Group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group and the like, alkenyl group (preferably having 2 to 20 carbon atoms, more preferably). Is an alkenyl group having 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include a vinyl group, an allyl group, a 2-butenyl group, and a 3-pentenyl group, and an alkynyl group (preferably a carbon atom). An alkynyl group having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, such as a propargyl group, 3 A pentynyl group), an aryl group (preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, such as a phenyl group and p-methyl group). A phenyl group, a naphthyl group, etc.), a substituted or unsubstituted amino group (preferably a carbon number of 0-20, more preferably a carbon number of 0-10, particularly preferably a carbon number of 0-6, For example, an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, a dibenzylamino group and the like, an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably Is an alkoxy group having 1 to 8 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group), an aryloxy group (preferably Or an aryloxy group having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include a phenyloxy group and a 2-naphthyloxy group), acyl Group (preferably having 1 to 20 carbon atoms, more preferably having 1 to 16 carbon atoms, and particularly preferably having 1 to 12 carbon atoms, and examples thereof include acetyl group, benzoyl group, formyl group, and pivaloyl group) An alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include a methoxycarbonyl group and an ethoxycarbonyl group. ), An aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, particularly preferably Is an aryloxycarbonyl group having 7 to 10 carbon atoms, such as a phenyloxycarbonyl group, and an acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably carbon atoms). An acyloxy group having 2 to 10 carbon atoms, such as an acetoxy group and a benzoyloxy group, and an acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 carbon atoms). 10 to 10 acylamino groups such as acetylamino group and benzoylamino group), alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 carbon atoms). To 12 alkoxycarbonylamino groups, such as methoxycarbonylamino group, etc. An aryloxycarbonylamino group (preferably an aryloxycarbonylamino group having preferably 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, and particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino group). Group), a sulfonylamino group (preferably a sulfonylamino group having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methanesulfonylamino group, A benzenesulfonylamino group), a sulfamoyl group (preferably a sulfamoyl group having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, and particularly preferably 0 to 12 carbon atoms. For example, a sulfamoyl group, methyl Sulfamoyl group, dimethylsulfamoyl group, phenylsulfur A carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as an unsubstituted carbamoyl group). A methylcarbamoyl group, a diethylcarbamoyl group, a phenylcarbamoyl group and the like), an alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms). For example, a methylthio group, an ethylthio group and the like), an arylthio group (preferably an arylthio group having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, and particularly preferably 6 to 12 carbon atoms. Phenylthio group and the like), sulfonyl group (preferably having 1 to 20 carbon atoms, more preferred) Or a sulfonyl group having 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a mesyl group and a tosyl group, and a sulfinyl group (preferably having a carbon number of 1 to 20, more preferably carbon. A sulfinyl group having 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methanesulfinyl group and a benzenesulfinyl group, and a ureido group (preferably having 1 to 20 carbon atoms, more preferably a carbon number). 1 to 16, particularly preferably a ureido group having 1 to 12 carbon atoms, and examples thereof include an unsubstituted ureido group, a methylureido group, and a phenylureido group, and a phosphoric acid amide group (preferably having a carbon number of 1 to 1). 20, more preferably a phosphoric acid amide group having 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a diethylphosphoric acid amide group Phenyl phosphoric acid amide group, etc.), hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, A sulfino group, a hydrazino group, an imino group, a heterocyclic group (preferably a heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12, and having a heteroatom such as a nitrogen atom, an oxygen atom, a sulfur atom, etc. A heterocyclic group, for example, an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group, a piperidyl group, a morpholino group, a benzoxazolyl group, a benzimidazolyl group, a benzthiazolyl group, etc.), a silyl group (preferably, C3-C40, more preferably C3-C30, particularly preferably C3-C24 A group, such as trimethylsilyl group, etc. triphenylsilyl group), and the like. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be bonded to each other to form a ring.

R ³ , R ⁴ and R ⁵ are preferably an alkyl group or a hydrogen atom, and more preferably a hydrogen atom.

In the formula, X ¹ and X ² each independently represent a divalent linking group or a single bond. The divalent linking group is not particularly limited, but is preferably an arylene group, —O—, —S—, or —NR ³¹ — (R ³¹ represents a hydrogen atom or a substituent, and the substituent is R ^3. , R ⁴ and R ⁵ are the same as the examples of the substituents respectively represented, and R ³¹ is preferably an alkyl group, the aforementioned Rf, or a hydrogen atom, more preferably a hydrogen atom) alone or , And more preferably —O—, —S— or —NR ³¹ —. X ¹ and X ² are more preferably —O— or —NR ³¹ —, still more preferably —O— or —NH—, and particularly preferably —O—.

In the above formula, Z represents a divalent linking group or a single bond. The divalent linking group is not particularly limited, but is preferably an alkylene group, an arylene group, -C (= O)-, -O-, -S-, -S (= O)-, -S (= O) ₂ — or —NR ³² — (R ³² represents a hydrogen atom or a substituent, and the substituent is the same as the examples of the substituent represented by R ³ , R ⁴ and R ⁵ , and preferably R ³² is alkyl. A group or a hydrogen atom, more preferably a hydrogen atom), or a group obtained by combining them alone, more preferably an alkylene group having 1 to 12 carbon atoms, an arylene group having 6 to 12 carbon atoms,- C (═O) —, —O—, —S—, —S (═O) —, —S (═O) ₂ —, or —NR ³² — is a group obtained alone or in combination. More preferably, Z is an alkylene group having 1 to 8 carbon atoms, -C (= O)-, -O-, -S-, -S (= O)-, -S (= O) _2- or -NR. ³² - a alone or a group obtained by their combination, for example,

Etc.
In the above formula, M ⁺ represents a cationic substituent, and M ⁺ is preferably an organic cationic substituent, more preferably an organic cationic group containing a nitrogen or phosphorus atom. More preferred is a pyridinium cation or an ammonium cation, and more preferred is a trialkylammonium cation represented by the following general formula (2).

In the above formula, R ¹³ , R ¹⁴ and R ¹⁵ each independently represents a substituted or unsubstituted alkyl group. As the substituent, those mentioned as the substituents for R ³ , R ⁴ and R ⁵ can be applied. R ¹³ , R ^14, and R ¹⁵ may be combined with each other to form a ring, if possible. R ¹³ , R ¹⁴ and R ¹⁵ are preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and still more preferably a methyl group, an ethyl group, or a methyl carboxyl group. And particularly preferably a methyl group.

In the above formula, Y ⁻ represents a counter anion and may be an inorganic anion or an organic anion. Further, when the charge becomes 0 in the molecule, Y ⁻ may not be present. Preferred examples of the inorganic anion include iodo ion, bromine ion, and chlorine ion. Preferable organic anions include p-toluenesulfonate ion, benzenesulfonate ion, methanesulfonate ion, trifluoromethanesulfonate ion, and the like. Y ^- is more preferably iodo ion, p-toluenesulfonic acid ion or benzenesulfonic acid ion, and still more preferably p-toluenesulfonic acid.

  In the above formula, m is 0 or 1, preferably 0.

  Among the compounds represented by the general formula (1), compounds represented by the following general formula (1-a) are preferable.

In the formula, R ¹¹ and R ²¹ each independently represent a substituted or unsubstituted alkyl group, but at least one of R ¹ and R ² represents the aforementioned Rf, and the total number of carbon atoms of R ¹¹ and R ²¹ Is 19 or less. R ¹³ , R ¹⁴ and R ¹⁵ each independently represents a substituted or unsubstituted alkyl group, and may be bonded to each other to form a ring. X ¹¹ and X ²¹ each independently represent —O—, —S—, or —NR ³¹ —, R ³¹ represents a hydrogen atom or a substituent, and Z represents a divalent linking group or a single bond. Y ⁻ represents a counter anion, but Y ⁻ may not be present when the charge is 0 in the molecule.
m is 0 or 1. In the formula, Z and Y ⁻ are each independently synonymous with those in the general formula (1), and preferred ranges thereof are also the same. About R <^13> , R <^14> , R <^15> and m, it is synonymous with those in the said General formula (1), respectively, A preferable range is also the same.

In the formula, X ¹¹ and X ¹² are each independently —O—, —S— or —NR ³¹ — (R ³¹ represents a hydrogen atom or a substituent, and the substituents include R ³ , R ⁴ and R ^Examples of the substituent of ⁵ are applicable, and R ³¹ is preferably an alkyl group, the aforementioned Rf, or a hydrogen atom, more preferably a hydrogen atom, and X ¹¹ and X ²¹ are more preferably —O. -, -NH-, more preferably -O-.

In the above formula, R ¹¹ and R ²¹ are each independently synonymous with R ¹ and R ² in the general formula (1), and preferred ranges are also the same. However, the total number of carbon atoms of R ¹¹ and R ²¹ is 19 or less. m is 0 or 1.

  Although the specific example of a compound represented by the said General formula (1) is given, this invention is not restrict | limited at all by the following specific examples. In addition, unless otherwise indicated in the structure description of the following exemplary compounds, an alkyl group and a perfluroalkyl group mean a linear structure. Of the abbreviations in the notation, 2EH means 2-ethylhexyl.

  Next, although an example of the general synthesis | combining method of the compound represented by the said general formula (1) of this invention and (1-a) is shown, this invention is not limited to these.

  The compound of the present invention can be synthesized using a fumaric acid derivative, a maleic acid derivative, an itaconic acid derivative, a glutamic acid derivative, an aspartic acid derivative, or the like as a raw material. For example, when a fumaric acid derivative, a maleic acid derivative or an itaconic acid derivative is used as a raw material, the double bond can be synthesized by performing a Michael addition reaction with a nucleophilic species and then cationizing with an alkylating agent. .

The fluorine compound can also have an anionic hydrophilic group.
An anionic hydrophilic group means an acidic group having a pKa of 7 or less and an alkali metal salt or ammonium salt thereof. Specific examples include a sulfo group, a carboxyl group, a phosphonic acid group, a carbamoylsulfamoyl group, a sulfamoylsulfamoyl group, an acylsulfamoyl group, and salts thereof. Of these, a sulfo group, a carboxyl group, a phosphonic acid group and salts thereof are preferable, and a sulfo group and salts thereof are more preferable. Examples of the cationic species that form salts include lithium, sodium, potassium, cesium, ammonium, tetramethylammonium, tetrabutylammonium, and methylpyridinium, and lithium, sodium, potassium, and ammonium are preferable.

A preferable fluorine compound having an anionic hydrophilic group in the present invention is represented by the following general formula (3).
General formula (3)

In the formula, R ¹ and R ² each independently represent an alkyl group, but at least one of them represents Rf. When R ¹ and R ² represent an alkyl group that is not a fluorinated alkyl group, an alkyl group having 2 to 18 carbon atoms is preferable, and an alkyl group having 4 to 12 carbon atoms is more preferable. R ³ and R ⁴ each independently represents a hydrogen atom or a substituted or unsubstituted alkyl group.
Specific examples of the fluorinated alkyl group represented by R ¹ and R ² include the aforementioned fluorinated alkyl group, and the preferred structure is also the structure represented by the aforementioned general formula (A). Moreover, the preferable structure in it is the same as that of the description of the above-mentioned fluorinated alkyl group. All of the alkyl groups represented by R ¹ and R ² are preferably the aforementioned fluorinated alkyl groups.
The substituted or unsubstituted alkyl group represented by R ³ and R ⁴ may be linear, branched, or have a cyclic structure. The substituent is not particularly limited, and examples thereof include an alkenyl group, an aryl group, an alkoxy group, a halogen atom (preferably Cl), a carboxylic ester group, a carbonamido group, a carbamoyl group, an oxycarbonyl group, and a phosphoric ester group. preferable.
A represents -L _b -SO ₃ M, M represents a cation. Here, preferable examples of the cation represented by M include alkali metal ions (lithium ions, sodium ions, potassium ions, etc.), alkaline earth metal ions (barium ions, calcium ions, etc.), ammonium ions, and the like. . Of these, lithium ions, sodium ions, potassium ions or ammonium ions are more preferred, lithium ions, sodium ions or potassium ions are more preferred, and the total number of carbon atoms and substituents of the compound of the general formula (3), It can be appropriately selected depending on the degree of branching of the alkyl group. In the case where the total number of carbon atoms of R ¹ , R ² , R ³ and R ⁴ is 16 or more, if M is a lithium ion, both the solubility (particularly with respect to water) and the antistatic ability or coating uniformity can be achieved. Is excellent.
L _b represents a single bond or a substituted or unsubstituted alkylene group. As the substituent, those exemplified for R ³ are preferable. When L _b is an alkylene group, the number of carbon atoms is preferably 2 or less. L _b is preferably a single bond or a —CH ₂ — group, and most preferably a —CH ₂ — group.
The general formula (3) is more preferably a combination of the above preferred embodiments.

Specific examples of the fluorine compound having an anionic hydrophilic group according to the present invention are illustrated below, but the present invention is not limited to the following specific examples.
Unless otherwise specified, in the structure notation of the following exemplified compounds, an alkyl group and a perfluoroalkyl group mean a straight chain structure.

The said fluorine compound can also have a nonionic hydrophilic group.
The nonionic hydrophilic group means a group that dissolves in water without dissociating into ions. Specific examples include poly (oxyethylene) alkyl ethers and polyhydric alcohols, but are not limited thereto.

In the present invention, a preferred nonionic fluorine compound is represented by the following general formula (4).
General formula (4)

  In the general formula (4), Rf is the above-mentioned fluorinated alkyl group, specific examples of Rf include the above-mentioned groups, and a preferred structure is also a structure represented by the above-mentioned general formula (A). In addition, preferred structures in the same are the same as those described for Rf.

X in the general formula (4) represents a divalent linking group and is not particularly limited.

Etc.
In General formula (4), n is 2 or 3, and m represents the integer of 1-30. R is a group having one or more hydrogen atoms, alkyl groups, aryl groups, heterocyclic groups, Rf, or Rf as a substituent.

  Specific examples of the nonionic fluorine compound used in the present invention are illustrated below, but the present invention is not limited to the following specific examples.

  The compound having a specific fluorinated alkyl group that can be used in the present invention is used as a surfactant to form a layer constituting a photosensitive material (particularly, a protective layer, an undercoat layer, a back layer, etc.). It is preferably used for a coating composition. Among them, it is particularly preferable to use it for forming the outermost layer of the photosensitive material because effective antistatic ability and coating uniformity can be obtained. Furthermore, it has been found that the structure of the present invention is effective for improving the storage stability and use environment dependency of the present invention. In order to obtain this effect, the fluorine compound of the present invention is preferably used in the outermost layer of the image forming layer surface or the back surface. Moreover, the same effect can be obtained even if it is used for the support undercoat layer.

The amount of the specific fluorine compound used in the present invention is not particularly limited, and the amount used can be arbitrarily selected according to the structure and location of the fluorine compound used, the type and amount of other materials contained in the composition, and the like. Can be determined. For example, when used as a coating solution for the outermost layer of the photothermographic material, the coating amount of the fluorine compound in the coating composition is preferably 0.1 mg / m ² or more and 100 mg / m ² or less, 0.5 mg / m is more preferably ² or more 20 mg / m ² or less.

  In the present invention, one type of the above specific fluorine compound may be used alone, or two or more types may be mixed and used. Moreover, it can also use together with surfactants other than the said specific fluorine compound.

(Hardener)
A hardener may be used for each layer such as the photosensitive layer, protective layer, and back layer in the present invention. Examples of hardeners include T.W. H. There are various methods described in “THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION” by James (published by Macmillan Publishing Co., Inc., published in 1977), pages 77 to 87. -S-triazine sodium salt, N, N-ethylenebis (vinylsulfoneacetamide), N, N-propylenebis (vinylsulfoneacetamide), polyvalent metal ions described on page 78 of the same, U.S. Pat. No. 4,281, Polyisocyanates such as 060 and JP-A-6-208193, epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A 62-89048 are preferably used.

  The hardening agent is added as a solution, and the addition time of this solution into the protective layer coating solution is from 180 minutes before to immediately before application, preferably from 60 minutes to 10 seconds before application. As long as the effects of the present invention are sufficiently exhibited, there is no particular limitation. Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method using a static mixer described in Chapter 8 of Nienow's “Liquid Mixing Technology” (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

(Antistatic agent)
In the present invention, it is preferable to have a conductive layer containing a metal oxide or a conductive polymer. The antistatic layer may serve as an undercoat layer, a back layer surface protective layer, or the like, or may be provided separately. As the conductive material for the antistatic layer, a metal oxide in which conductivity is improved by introducing oxygen defects or different metal atoms into the metal oxide is preferably used. Examples of metal oxides are preferably ZnO, TiO ₂ and SnO _2. Addition of Al and In to ZnO, addition of Sb, Nb, P and halogen elements to SnO ₂ , and addition to TiO _2. For example, addition of Nb, Ta or the like is preferable. In particular, SnO ₂ added with Sb is preferable. The amount of different atoms added is preferably in the range of 0.01 to 30 mol%, more preferably in the range of 0.1 to 10 mol%. The shape of the metal oxide may be spherical, needle-like, or plate-like, but the long axis / uniaxial ratio is 2.0 or more, preferably 3.0 to 50 in terms of the effect of imparting conductivity. Good. Range amount preferably of 1mg / m ² ~1000mg / m ² of metal oxide, more preferably 10mg / m ² ~500mg / m ² range, more preferably at 20mg / m ² ~200mg / m ² It is a range. The antistatic layer in the present invention may be disposed on either the emulsion surface side or the back surface side, but is preferably disposed between the support and the back layer. Specific examples of the antistatic layer in the present invention are disclosed in paragraph No. 0135 of JP-A No. 11-65021, JP-A Nos. 56-143430, 56-143431, 58-62646, No. 56-120519, JP-A No. 11-120. No. 84573, paragraph numbers 0040 to 0051, US Pat. No. 5,575,957, and JP-A No. 11-223898, paragraph numbers 0078 to 0084.

(Support)
The transparent support is a polyester, particularly polyethylene, which has been heat-treated in a temperature range of 130 to 185 ° C. in order to relieve internal strain remaining in the film during biaxial stretching and to eliminate thermal shrinkage strain generated during heat development. Terephthalate is preferably used. In the case of a photothermographic material for medical use, the transparent support may be colored with a blue dye (for example, dye-1 described in Examples of JP-A-8-240877) or may be uncolored. Examples of the support include water-soluble polyesters disclosed in JP-A-11-84574, styrene-butadiene copolymers described in JP-A-10-186565, and vinylidene chloride described in JP-A-2000-39684 and Japanese Patent Application No. 11-106881, paragraph numbers 0063 to 0080. It is preferable to apply an undercoating technique such as a copolymer. When the emulsion layer or the back layer is coated on the support, the water content of the support is preferably 0.5% by mass or less.

(Other additives)
An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, or a coating aid may be further added to the photothermographic material. Various additives are added to either the photosensitive layer or the non-photosensitive layer. With respect to these, WO 98/36322, EP 803764A1, JP-A-10-186567, 10-18568 and the like can be referred to.

1-7. Packaging material The photosensitive material of the present invention is packaged with a packaging material having low oxygen permeability and / or moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curling, curling, etc. Is preferred. The oxygen permeability is preferably 50 ml / atm · m ² · day or less at 25 ° C., more preferably 10 ml / atm · m ² · day or less, more preferably 1.0 ml / atm · m ² · day or less. is there. The moisture permeability is preferably 10 g / atm · m ² · day or less, more preferably 5 g / atm · m ² · day or less, and still more preferably 1 g / atm · m ² · day or less.
As a specific example of the packaging material having a low oxygen permeability and / or moisture permeability, for example, JP-A-8-254793. This is a packaging material described in JP-A-2000-206653.

1-8. Other usable techniques Examples of techniques that can be used in the photothermographic material of the present invention include EP80376A1, EP883022A1, WO98 / 36322, JP-A-56-62648, 58-62644, and JP-A-9-. 43766, 9-281737, 9-297367, 9-304869, 9-31405, 9-329865, 10-10669, 10-62899, 10-69023, 10-186568, 10-90823, 10-171106, 10-186565, 10-186567, 10-186567 to 10-186572, 10-197974, 10- 197982, 10-197983, 10-197985 to 10-1 No. 97987, No. 10-207001, No. 10-207004, No. 10-221807, No. 10-282601, No. 10-288823, No. 10-288824, No. 10-307365, No. 10-312038 10-339934, 11-7100, 11-15105, 11-24200, 11-24201, 11-30832, 11-84574, 11-65021, 11-109547, 11-125880, 11-129629, 11-133536 to 11-133539, 11-133542, 11-133543, 11-223898, 11- 352627, 11-305377, 11-305378, 11-305384 11-305380, 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, JP-A 2000-187298, 2000-10229, 2000-47345, 2000-206642, 2000-98530, 2000-98531, 2000-112059, 2000-112060, 2000-112104, 2000 No.-1112064 and 2000-171936.

In the case of a multicolor color photothermographic material, each emulsion layer is generally a functional or non-functional barrier layer between each photosensitive layer as described in US Pat. No. 4,460,681. Are used to keep them distinguished from each other.
The construction in the case of a multicolor color photothermographic material may include a combination of these two layers for each color and all within a single layer as described in US Pat. No. 4,708,928. Ingredients may be included.

1-9. Application Method The photothermographic material in the invention may be applied by any method. Specifically, various coating operations including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. And Stephen F. Kistler, Peter M. et al. Extrusion coating or slide coating described in pages 399 to 536 of “LIQUID FILM COATING” (CHAPMAN & HALL, 1997) by Schweizer is preferably used, and slide coating is particularly preferably used. An example of the shape of a slide coater used for slide coating is shown in FIG. 11b. 1 If desired, two or more layers can be simultaneously coated by the method described on pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent No. 837,095. . In the present invention, particularly preferred coating methods are those described in JP-A Nos. 2001-194748, 2002-153808, 2002-153803, and 2002-182333.

The organic silver salt-containing layer coating solution in the present invention is preferably a so-called thixotropic fluid. Regarding this technique, JP-A-11-52509 can be referred to. The viscosity of the organic silver salt-containing layer coating solution in the present invention is preferably 400 mPa · s or more and 100,000 mPa · s or less, more preferably 500 mPa · s or more and 20,000 mPa · s or less, at a shear rate of 0.1 S ⁻¹ . Further, at a shear rate of 1000 S ⁻¹ , 1 mPa · s to 200 mPa · s is preferable, and 5 mPa · s to 80 mPa · s is more preferable.

In the case of preparing the coating liquid in the present invention, when mixing two kinds of liquids, a known in-line mixer or implant mixer is preferably used. A preferable in-line mixer in the present invention is described in JP-A No. 2002-85948, and an implant mixer is described in JP-A No. 2002-90940.
The coating solution in the present invention is preferably subjected to defoaming treatment in order to keep the coated surface state good. About the preferable defoaming processing method in this invention, it is the method described in Unexamined-Japanese-Patent No. 2002-66431.
When applying the coating solution in the present invention, it is preferable to perform static elimination in order to prevent adhesion of dust, dust, and the like due to electric resistance of the support. An example of a preferable static elimination method in the present invention is described in JP-A No. 2002-143747.
In the present invention, it is important to precisely control the drying air and the drying temperature in order to dry the non-setting image forming layer coating solution. Preferred drying methods in the present invention are described in detail in JP-A Nos. 2001-194749 and 2002-139814.
The photothermographic material of the present invention is preferably subjected to heat treatment immediately after coating and drying in order to improve the film formability. The temperature of the heat treatment is preferably in the range of 60 ° C. to 100 ° C. as the film surface temperature, and the heating time is preferably in the range of 1 second to 60 seconds. A more preferable range is a range where the film surface temperature is 70 ° C. to 90 ° C. and the heating time is 2 to 10 seconds. A preferable heat treatment method in the present invention is described in JP-A No. 2002-107872.
In order to stably and continuously produce the photothermographic material of the present invention, the production methods described in JP-A Nos. 2002-156728 and 2002-182333 are preferably used.

  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).

2. Image Forming Method 1) Exposure Red to infrared emission He—Ne laser, red semiconductor laser, blue to green emission Ar ⁺ , He—Ne, He—Cd laser, blue semiconductor laser. Preferably, it is a red to infrared semiconductor laser, and the peak wavelength of the laser beam is 600 nm to 900 nm, preferably 620 nm to 850 nm. On the other hand, in recent years, in particular, a module in which a SHG (Second Harmonic 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. The blue semiconductor laser is expected to increase in demand in the future because high-definition image recording is possible, the recording density is increased, and a stable output is obtained with a long lifetime. The peak wavelength of the blue laser light is preferably 300 nm to 500 nm, particularly preferably 400 nm to 500 nm.
It is also preferable that the laser light oscillates vertically in a multi-frequency manner such as high frequency superposition.

2) Photothermographic development The photothermographic material of the present invention may be developed by any method, but is usually developed by raising the temperature of the photothermographic material exposed imagewise. A preferred development temperature is 80 to 250 ° C, preferably 100 to 140 ° C, more preferably 110 to 130 ° C. The development time is preferably 1 to 60 seconds, more preferably 3 to 30 seconds, still more preferably 5 to 25 seconds, and 7 to 15 seconds.

  Either a drum type heater or a plate type heater may be used as the thermal development method, but the plate type heater method is more preferable. The heat development method using the plate type heater method is preferably a method described in JP-A-11-133572, and a visible image is obtained by bringing a photothermographic material having a latent image formed thereon into contact with a heating means in a heat developing unit. In the image recording apparatus, the heating unit includes a plate heater, and a plurality of press rollers are disposed to face each other along one surface of the plate heater, and the press roller is disposed between the press roller and the plate heater. An image recording apparatus characterized in that heat development is performed by passing a photothermographic material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature about 1 ° C. to 10 ° C. at the tip. For example, there are examples in which four sets of plate heaters that can be independently controlled are used and controlled so as to be 112 ° C., 119 ° C., 121 ° C., and 120 ° C., respectively. Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and rapidly develop the photothermographic material. It is also possible to suppress a change in the shape of the support of the photothermographic material due to the heating.

  In order to reduce the size of the image recording apparatus and shorten the heat development time, it is preferable that more stable heater control is possible. In addition, the exposure of one sheet of photosensitive material is started from the top and the exposure is completed to the rear end. It is desirable to start the heat development before the time. Imagers capable of rapid processing preferable for the present invention are described in, for example, JP-A Nos. 2002-289804 and 2002-287668. If this imager is used, for example, heat development can be performed in 14 seconds with a three-stage plate heater controlled at 107 ° C.-121 ° C.-121 ° C. The output time of the first sheet is shortened to about 60 seconds. be able to. For such rapid development processing, it is preferable to use the photothermographic material-2 of the present invention in combination with high sensitivity and less susceptible to environmental temperature. A preferred image recording apparatus according to the present invention is shown in FIG.

The image recording apparatus 10 includes trays 36, 38, and 40 for stocking photothermographic materials, a laser exposure unit 54, a thermal development unit 60, a cooling unit 68, and a discharge unit 70.
The other names in FIG. 1 will be described. The paper 16, the barcode reading windows 37, 39, 41, the barcode readers 43, 45, 47, the sheet feeding mechanisms 48, 50, 52, the plate heaters 64a, b, c, roller 62, drum 66, photothermographic material F, and laser beam L.

  In the present invention, the image recording apparatus has a heat developing part having a driving roller and a plate heater, the surface side having the image forming layer is brought into contact with the driving roller, and the side having the back layer An image forming method in which the surface is brought into contact with the plate heater and developed by heating can be used. Since the photothermographic material of the present invention has very good transportability, it is possible to carry out heat development by bringing the surface into contact with a driving roller and a plate heater.

3) System As a medical laser imager provided with an exposure part and a heat development part, Fuji Medical Dry Laser Imager FM-DPL and DRYPIX7000 can be exemplified. Regarding FM-DPL, Fuji Medical Review No. 8, pages 39 to 55, and it goes without saying that these techniques are applied as a laser imager of the photothermographic material of the present invention. Further, it can also be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Film Medical Co., Ltd. as a network system adapted to the DICOM standard.

<Use of the present invention>
The photothermographic material of the present invention forms a black and white image by a silver image, and is used as a photothermographic material for medical diagnosis, a photothermographic material for industrial photography, a photothermographic material for printing, and a photothermographic material for COM. It is preferably used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of PET support)
1) Film formation Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) is obtained. It was. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to produce an unstretched film having a thickness of 175 μm after heat setting.

This was stretched 3.3 times longitudinally using rolls with different peripheral speeds, and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends, and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

2) Surface corona discharge treatment Using a solid state corona discharge treatment machine 6KVA model manufactured by Pillar, 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 processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

3) Undercoat 1) Preparation formulation of undercoat layer coating solution (1) (for photosensitive layer side undercoat layer)
59 g of pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 10% by mass solution 5.4 g
MP-1000 manufactured by Soken Chemical Co., Ltd. (polymer fine particles, average particle size 0.4 μm)
0.91g
935 ml of distilled water

Formula (2) (for back layer 1st layer)
Styrene-butadiene copolymer latex 158g
(Solid content 40% by mass, styrene / butadiene mass ratio = 68/32)
2,4-dichloro-6-hydroxy-S-triazine sodium salt (8% by mass aqueous solution)
20g
10% 1% by weight aqueous solution of sodium laurylbenzenesulfonate
854 ml of distilled water

Formula (3) (for back side second layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion)
84g
Gelatin (10 mass% aqueous solution) 89.2g
8.6 g of Metroise TC-5 (2% by mass aqueous solution) manufactured by Shin-Etsu Chemical Co., Ltd.
MP-1000 0.01g manufactured by Soken Chemical Co., Ltd.
10% 1% by weight aqueous solution of sodium dodecylbenzenesulfonate
NaOH (1% by mass) 6 ml
Proxel (ICI) 1ml
805 ml of distilled water

2) Undercoat After the corona discharge treatment is performed on both sides of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm, the undercoat coating solution formulation (1) is wet coated with a wire bar on one side (photosensitive layer surface). Apply to a volume of 6.6 ml / m ² (per side) and dry at 180 ° C. for 5 minutes, and then wet coat the above-mentioned undercoat coating liquid formulation (2) on the back side (back side) with a wire bar. Was applied at a temperature of 5.7 ml / m ² , dried at 180 ° C. for 5 minutes, and the wet coating amount of the undercoat coating liquid formulation (3) on the back surface (back surface) was 7.7 ml / m with a wire bar. ² was applied and dried at 180 ° C. for 6 minutes to prepare an undercoat support.

(Back layer)
1) Preparation of back layer coating solution (Preparation of solid fine particle dispersion (a) of base precursor)
Add 2.5 kg of Base Precursor Compound 1 and 300 g of a surfactant (trade name: Demol N, manufactured by Kao Corporation), 800 g of diphenylsulfone, 1.0 g of benzoisothiazolinone sodium salt and distilled water to make a total amount. The mixture was mixed to 8.0 kg, and the mixed solution was dispersed with beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation). In the dispersion method, the mixed solution was fed to UVM-2 filled with zirconia beads having an average diameter of 0.5 mm by a diaphragm pump, and dispersed at an internal pressure of 50 hPa or more until a desired average particle size was obtained.
The dispersion was subjected to spectral absorption measurement, and the ratio of the absorbance at 450 nm to the absorbance at 650 nm (D ₄₅₀ / D ₆₅₀ ) in the spectral absorption of the dispersion was dispersed to 3.0. The obtained dispersion was diluted with distilled water so that the concentration of the base precursor was 25% by mass, and was filtered for removal of dust (polypropylene filter having an average pore size of 3 μm) for practical use.

2) Preparation of Dye Solid Fine Particle Dispersion 6.0 kg of cyanine dye compound-1 and 3.0 kg of sodium p-dodecylbenzenesulfonate, 0.6 kg of surfactant Demol SNB manufactured by Kao Corporation, and antifoaming agent (trade name) : Surfynol 104E, manufactured by Nissin Chemical Co., Ltd.) 0.15 kg was mixed with distilled water to make a total liquid volume of 60 kg. The mixed solution was dispersed with 0.5 mm zirconia beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation).
The dispersion was dispersed until the ratio of the absorbance at 650 nm to the absorbance at 750 nm (D ₆₅₀ / D ₇₅₀ ) in the spectral absorption of the dispersion was 5.0 or more. The obtained dispersion was diluted with distilled water so that the concentration of the cyanine dye was 6% by mass, and subjected to filter filtration (average pore size: 1 μm) for removing dust.

3) Preparation of antihalation layer coating solution Keep container at 40 ° C., gelatin 40 g, monodisperse polymethyl methacrylate fine particles (average particle size 8 μm, particle size standard deviation 0.4) 20 g, benzoisothiazolinone 0.1 g, 490 ml of water was added to dissolve the gelatin. Furthermore, 2.3 ml of 1 mol / l sodium hydroxide aqueous solution, 40 g of the dye solid fine particle dispersion, 90 g of the solid fine particle dispersion (a) of the base precursor, 12 ml of 3% by weight aqueous sodium polystyrenesulfonate solution, 10% by weight of SBR latex 180 g of the liquid was mixed. Immediately before coating, 80 ml of a 4% by weight aqueous solution of N, N-ethylenebis (vinylsulfonacetamide) was mixed to prepare a coating solution for preventing halation.

4) Preparation of back surface protective layer coating solution (Preparation of back surface protective layer coating solution-1) << Comparative Example >>
The container was kept at 40 ° C., and 40 g of gelatin, 35 mg of benzoisothiazolinone, and 840 ml of water were added to dissolve the gelatin. Further, 5.8 ml of 1 mol / l sodium hydroxide aqueous solution, 1.5 g of liquid paraffin emulsion as liquid paraffin, 10 ml of 5% by weight aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, 20 ml of 3% by weight aqueous sodium polystyrene sulfonate solution 2.4 ml of a 2 mass% solution of fluorine compound-A, 2.4 ml of a 2 mass% solution of fluorine compound-B, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass) Ratio: 58/8/27/5/2, Tg: 42 ° C., I / O value: 0.555) Latex (Comparative Latex 1) 45% 20% liquid was mixed. Immediately before coating, 25 ml of a 4% by weight aqueous solution of N, N-ethylenebis (vinylsulfonacetamide) was mixed to prepare a coating solution for the back surface protective layer.

(Preparation of back surface protective layer coating solution-2) << Comparative Example >>
The latex used in the preparation of the back surface protective layer coating solution-1 was a methyl methacrylate / butyl acrylate / acrylic acid copolymer (copolymerization mass ratio: 18/80/2, Tg: -34 ° C., I / O value: 0.490) Back surface protective layer coating solution-2 was prepared by changing to latex (comparative latex 2).

Preparation of (Back surface protective layer coating solution-3 to 15) << Invention >>
Back surface protective layer coating solutions-3 to 15 were prepared by changing the gelatin and latex used in the preparation of the back surface protective layer coating solution-1 as shown in Table 2.

4) Application of back layer On the back surface side of the undercoat support, the anti-halation layer coating solution was applied in water so that the gelatin coating amount was 0.52 g / m ² and the back surface protective layer coating solutions -1 to 15 were water-soluble. The simultaneous multilayer coating was carried out so that the coating amount of the conductive polymer was 1.7 g / m ² and dried to prepare back layers -1 to 15. The back layers -3 to 15 of the present invention had a better coated surface than the comparative back layer.

(Image forming layer, intermediate layer, and surface protective layer)
1. Preparation of coating materials 1) Silver halide emulsion << Preparation of silver halide emulsion 1 >>
To a solution of 1421 ml of distilled water, 3.1 ml of a 1% by mass potassium bromide solution was added, and a solution containing 3.5 ml of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 30 ° C., the solution A diluted with 95.4 ml of distilled water added to 22.22 g of silver nitrate, 15.3 g of potassium bromide and 0.8 g of potassium iodide in a distilled water volume of 97.4 ml. The whole amount of the solution B diluted to 1 was added at a constant flow rate over 45 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% by mass aqueous solution of benzimidazole was further added. Further, a solution C in which distilled water was added to 51.86 g of silver nitrate to be diluted to 317.5 ml, a solution D in which 44.2 g of potassium bromide and 2.2 g of potassium iodide were diluted with distilled water to a volume of 400 ml was added to solution C. Was added at a constant flow rate over 20 minutes, and solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of the solution C and the solution D so as to be 1 × 10 ⁻⁴ mol per mol of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁴ mol was added and aged for 91 minutes. Thereafter, a methanol solution having a molar ratio of the spectral sensitizing dye A and the sensitizing dye B of 3: 1 was added in an amount of 1.2 × 10 ⁻³ mol as a total of the sensitizing dyes A and B per mol of silver. , N′-dihydroxy-N ″, N ″ -diethylmelamine in 0.8 ml methanol solution was added, and after 4 minutes, 5-methyl-2-mercaptobenzimidazole was added with methanol solution per mole of silver. 4.8 × 10 ⁻³ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole was added in methanol solution to 5.4 × 10 ⁻³ mol and 1- ( 3-Methylureidophenyl) -5-mercaptotetrazole was added in an aqueous solution to 8.5 × 10 ⁻³ mol per mol of silver to prepare silver halide emulsion 1.

  The grains in the silver halide emulsion thus prepared were silver iodobromide grains containing 3.5 mol% of iodine having an average equivalent sphere diameter of 0.042 μm and a variation coefficient of 20% of the equivalent sphere diameter. The particle size and the like were determined from an average of 1000 particles using an electron microscope. The {100} face ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of silver halide emulsion 2 >>
In the preparation of silver halide emulsion 1, the liquid temperature at the time of grain formation was changed from 30 ° C. to 47 ° C., and solution B was changed to diluting 15.9 g of potassium bromide with distilled water to a volume of 97.4 ml, Solution D was changed to diluting 45.8 g of potassium bromide with distilled water to a volume of 400 ml, and the addition time of solution C was changed to 30 minutes to remove potassium hexacyanoiron (II) in the same manner. A silver halide emulsion 2 was prepared. Precipitation / desalting / washing / dispersion was carried out in the same manner as silver halide emulsion 1. Further, the addition amount of tellurium sensitizer C is 1.1 × 10 ⁻⁴ mol per mol of silver, and the addition amount of methanol solution of 3: 1 in the molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is silver. The total of sensitizing dye A and sensitizing dye B per mole is 7.0 × 10 ⁻⁴ mole, and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole is added to 1 mole of silver. Same as Emulsion 1 except that 3.3 × 10 ⁻³ mol and 1- (3-methylureidophenyl) -5-mercaptotetrazole were changed to 4.7 × 10 ⁻³ mol added to 1 mol of silver. Spectral sensitization, chemical sensitization, and addition of 5-methyl-2-mercaptobenzimidazole and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole were carried out to obtain silver halide emulsion 2. . The emulsion grains of the silver halide emulsion 2 were pure silver bromide cubic grains having an average sphere equivalent diameter of 0.080 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of silver halide emulsion 3 >>
In the preparation of silver halide emulsion 1, silver halide emulsion 3 was prepared in the same manner except that the liquid temperature at the time of grain formation was changed from 30 ° C. to 27 ° C. Further, precipitation / desalting / washing / dispersion was performed in the same manner as silver halide emulsion 1. The molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is 1: 1 as a solid dispersion (gelatin aqueous solution), and the addition amount is 6 × 10 ⁻ as the total of sensitizing dye A and sensitizing dye B per mole of silver. ³ moles, the amount of tellurium sensitizer C added was changed to 5.2 × 10 ⁻⁴ moles per mole of silver, and bromoauric acid was changed to 5 × 10 ⁻⁴ moles of silver 3 minutes after the addition of tellurium sensitizers. A silver halide emulsion 3 was obtained in the same manner as Emulsion 1 except that 2 × 10 ⁻³ mol of mol and potassium thiocyanate were added per mol of silver. The emulsion grains of the silver halide emulsion 3 were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.034 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of mixed emulsion A for coating solution >>
70% by weight of silver halide emulsion 1, 15% by weight of silver halide emulsion 2 and 15% by weight of silver halide emulsion 3 were dissolved, and 7% by mole of silver in a 1% by weight aqueous solution of benzothiazolium iodide. × 10 ^-3 mol was added. Further, water is added so that the content of silver halide per 1 kg of the mixed emulsion for coating solution is 38.2 g as silver, and 1- (3-methylureidophenyl) is adjusted to 0.34 g per 1 kg of the mixed emulsion for coating solution. -5-mercaptotetrazole was added.
Further, as "a compound in which a one-electron oxidant produced by one-electron oxidation can emit one or more electrons", each of compounds 1, 20 and 26 is 2 × 10 ⁻³ per mole of silver halide. Molar amounts were added.

2) Preparation of fatty acid silver dispersion << Preparation of fatty acid silver dispersion A >>
Henkel behenic acid (product name Edenor C22-85R) 87.6 kg, distilled water 423 L, 5 mol / L NaOH aqueous solution 49.2 L, t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react. To obtain a sodium behenate solution A. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution A and the total amount of the aqueous silver nitrate solution were each maintained at a constant flow rate for 93 minutes 15 Added over seconds and 90 minutes. At this time, only the aqueous silver nitrate solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution A is started. After the completion of the addition of the aqueous silver nitrate solution, only the sodium behenate solution A is added for 14 minutes and 15 seconds. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system of the sodium behenate solution A was prepared by keeping warm water by circulating hot water outside the double pipe so that the liquid temperature at the outlet of the addition nozzle tip was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution A and the addition position of the silver nitrate aqueous solution were symmetrically arranged around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of sodium behenate solution A, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.

  When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter. It was a flake-like crystal having a variation coefficient of 15% for a sphere equivalent diameter of 0.52 μm. (A, b, and c are the text provisions)

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to 1260 kg / cm ² by adjusting the pressure of the disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

<< Preparation of fatty acid silver dispersion B >>
<Preparation of recrystallized behenic acid>
100 kg of behenic acid (product name Edenor C22-85R) manufactured by Henkel was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 30 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour. The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then dried. When the obtained crystals were esterified and subjected to GC-FID measurement, the behenic acid content was 96 mol%, and in addition, lignoceric acid was 2 mol%, arachidic acid was 2 mol%, and erucic acid was 0.001 mol%. It was.

<Preparation of fatty acid silver dispersion B>
Recrystallized behenic acid 88 kg, distilled water 422 L, 5 mol / L NaOH aqueous solution 49.2 L and t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react to obtain sodium behenate solution B. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution B and the total amount of silver nitrate aqueous solution were kept at a constant flow rate for 93 minutes 15 Added over seconds and 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution B is started. After the addition of the aqueous silver nitrate solution is completed, only the sodium behenate solution B is added for 14 minutes and 15 seconds. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system for the sodium behenate solution B was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution B and the addition position of the silver nitrate aqueous solution were symmetrically arranged around the stirring axis, and were adjusted so as not to contact the reaction solution.

After completion of the addition of the sodium behenate solution B, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.
When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, average aspect ratio 2.1, and equivalent sphere diameter. It was a crystal with a variation coefficient of 11% (a, b, and c are defined in the text).

  19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurried with a dissolver blade, and a pipeline mixer (manufactured by Mizuho Kogyo Co., Ltd.). : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to a pressure of 1150 kg / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

3) Preparation of reducing agent dispersion << Preparation of reducing agent-1 dispersion >>
10 kg of water was added to 10 kg of a reducing agent-1 (2,2′-methylenebis- (4-ethyl-6-tert-butylphenol)) 10 kg and a 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Add and mix well to make a slurry. This slurry was fed with a diaphragm pump, dispersed for 3 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

<< Preparation of Reducing Agent-2 Dispersion >>
10 mass of reducing agent-2 (6,6′-di-t-butyl-4,4′-dimethyl-2,2′-butylidenediphenol) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour, and then further heated at 80 ° C. for 1 hour to obtain a reducing agent-2 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.50 μm and a maximum particle diameter of 1.6 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of hydrogen bonding compound-1 dispersion 10 kg of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of the aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, and dispersed for 4 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare a hydrogen bonding compound concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

5) Preparation of Development Accelerator-1 Dispersion 10 kg of Development Accelerator-1 and 20 kg of 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added with 10 kg of water and mixed well. To make a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the development accelerator to 20% by mass to obtain a development accelerator-1 dispersion. The development accelerator particles contained in the development accelerator dispersion thus obtained had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The obtained development accelerator dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
6) Preparation of Dispersion of Development Accelerator-2 and Color Adjuster-1 The solid dispersion of Development Accelerator-2 and Color Adjuster-1 was also dispersed by the same method as Development Accelerator-1, each having 20 mass. %, 15% by mass of a dispersion liquid was obtained.

7) Preparation of polyhalogen compound << Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (tribromomethanesulfonylbenzene), 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass to obtain an organic polyhalogen compound-1 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of an organic polyhalogen compound-2 (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by mass aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20 of sodium triisopropylnaphthalenesulfonate 0.4 kg of a mass% aqueous solution was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 30% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-2 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.3 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

8) Preparation of Phthalazine Compound-1 Solution 8 kg of Kuraray Co., Ltd. modified polyvinyl alcohol MP203 was dissolved in 174.57 kg of water, and then 3.15 kg of a 20 mass% aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 ( 14.28 kg of a 70% by weight aqueous solution of 6-isopropylphthalazine) was added to prepare a 5% by weight solution of phthalazine compound-1.

9) Preparation of mercapto compound << Preparation of aqueous solution of mercapto compound-1 >>
7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.

<< Preparation of Mercapto Compound-2 Aqueous Solution >>
20 g of mercapto compound-2 (1- (3-methylureidophenyl) -5-mercaptotetrazole) was dissolved in 980 g of water to obtain a 2.0 mass% aqueous solution.

10) Preparation of Pigment-1 Dispersion C.I. I. Pigment Blue 60 (64 g) and Kao Corp. Demol N (6.4 g) were added to 250 g of water and mixed well to obtain a slurry. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and disperse with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) for 25 hours. A pigment-1 dispersion was obtained by adjusting the concentration to 5% by mass. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

11) Preparation of SBR latex solution SBR latex was prepared as follows.
In a polymerization kettle of a gas monomer reactor (TAS-2J type manufactured by Pressure Glass Industrial Co., Ltd.), 287 g of distilled water and a surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)): solid content 48.5 (Mass%) 7.73 g, 1 mol / liter NaOH 14.06 ml, ethylenediaminetetraacetic acid tetrasodium salt 0.15 g, styrene 255 g, acrylic acid 11.25 g, tert-dodecyl mercaptan 3.0 g were put, the reaction vessel was sealed and the stirring speed was Stir at 200 rpm. After degassing with a vacuum pump and repeating nitrogen gas replacement several times, 108.75 g of 1,3-butadiene was injected to raise the internal temperature to 60 ° C. A solution obtained by dissolving 1.875 g of ammonium persulfate in 50 ml of water was added thereto, and the mixture was stirred as it was for 5 hours. The temperature was further raised to 90 ° C. and stirred for 3 hours. After the reaction was completed, the internal temperature was lowered to room temperature, and then Na ⁺ ion: NH ₄ ⁺ ion = 1: 1 using 1 mol / liter NaOH and NH ₄ OH. Addition treatment was performed so that the molar ratio was 5.3 (molar ratio), and the pH was adjusted to 8.4. Thereafter, the mixture was filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored, and 774.7 g of SBR latex was obtained. When the halogen ions were measured by ion chromatography, the chloride ion concentration was 3 ppm. As a result of measuring the concentration of the chelating agent by high performance liquid chromatography, it was 145 ppm.

  The latex has an average particle size of 90 nm, Tg = 17 ° C., solid content concentration of 44 mass%, equilibrium moisture content at 25 ° C. and 60% RH, 0.6 mass%, ion conductivity of 4.80 mS / cm (measurement of ion conductivity is A latex stock solution (44 mass%) was measured at 25 ° C. using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd.).

  SBR latexes having different Tg can be adjusted by the same method by appropriately changing the ratio of styrene and butadiene.

2. Preparation of coating solution 1) Preparation of image forming layer coating solution-1 1000 g of fatty acid silver dispersion A obtained above, 135 ml of water, 35 g of pigment-1 dispersion, 19 g of organic polyhalogen compound-1 dispersion, organic polyhalogen compound- 2 dispersion 58g, phthalazine compound-1 solution 162g, SBR latex (Tg: 17 ° C) liquid 1060g, reducing agent-1 dispersion 75g, reducing agent-2 dispersion 75g, hydrogen bonding compound-1 dispersion 106g, development 4.8 g of accelerator-1 dispersion, 9 ml of mercapto compound-1 aqueous solution and 27 ml of mercapto compound-2 aqueous solution were sequentially added, and 118 g of silver halide mixed emulsion A was added immediately before coating, followed by mixing well. The solution was fed directly to the coating die.

The viscosity of the image forming layer coating solution was 25 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 38 ° C. using RheoStress RS150 manufactured by Haake is 32, 35, 33, 26, and 17 [mPa · s] at shear rates of 0.1, 1, 10, 100, and 1000 [1 / second], respectively. s].

  The amount of zirconium in the coating solution was 0.32 mg per 1 g of silver.

2) Preparation of image forming layer coating liquid-2 1000 g of fatty acid silver dispersion B obtained above, 135 ml of water, 36 g of pigment-1 dispersion, 25 g of organic polyhalogen compound-1 dispersion, 39 g of organic polyhalogen compound-2 dispersion , 171 g of phthalazine compound-1 solution, 1060 g of SBR latex (Tg: 17 ° C.) liquid, 153 g of reducing agent-2 dispersion, 55 g of hydrogen bonding compound-1 dispersion, 4.8 g of development accelerator-1 dispersion, development acceleration Agent-2 dispersion 5.2 g, color tone modifier-1 dispersion 2.1 g, mercapto compound-2 aqueous solution 8 ml were sequentially added, and silver halide mixed emulsion A140 g was added immediately before coating and mixed well. The coating solution was fed directly to the coating die.
The viscosity of the image forming layer coating solution was 40 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 38 ° C. using a Haake RheoStress RS150 is 30, 43, 41, 28, 20 [mPa · s] at shear rates of 0.1, 1, 10, 100, 1000 [1 / second], respectively. s].

  The amount of zirconium in the coating solution was 0.30 mg per 1 g of silver.

3) Preparation of intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 163 g of pigment-1 dispersion, blue dye compound-1 (manufactured by Nippon Kayaku Co., Ltd .: Kayafect Turquoise RN Liquid 150) 33 g of aqueous solution, 27 ml of 5% by mass of di (2-ethylhexyl) sodium salt of sulfosuccinate, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 57/8/28/5/2) ) 27 ml of 5% aqueous solution of aerosol OT (manufactured by American Cyanamid Co.) was added to 4200 ml of latex 19% by weight, 135 ml of 20% by weight aqueous solution of diammonium phthalate, and water was added to a total amount of 10000 g. Adjust with NaOH so that pH is 7.5 The intermediate layer coating solution was fed to the coating die so as to be 8.9 ml / m ² .
The viscosity of the coating solution was 58 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of surface protective layer first layer coating solution 100 g of inert gelatin and 10 mg of benzoisothiazolinone were dissolved in 840 ml of water, and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio) 57/8/28/5/2) Latex 19% by weight solution 180g, phthalic acid 15% by weight methanol solution 46ml, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5% by weight aqueous solution 5.4ml was added. The mixture was mixed, and immediately before coating, 40 ml of 4% by weight chromium alum was mixed with a static mixer and fed to the coating die so that the amount of the coating solution was 26.1 ml / m ² .
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

5) Preparation of surface protective layer second layer coating solution 100 g of inert gelatin and 10 mg of benzoisothiazolinone are dissolved in 800 ml of water and 8.0 g of liquid paraffin emulsion as liquid paraffin, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl 5. Methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) 19% by weight of latex 19% by weight liquid 180% phthalic acid 15% by weight methanol solution 40ml, 1% by weight solution of fluorine compound-A 5. 5 ml, 5.5 ml of a 1% by weight aqueous solution of fluorine compound-B, 28 ml of a 5% by weight aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm), polymethyl Mixed with 21 g of methacrylate fine particles (average particle size 4.5 μm) The ones and the surface protective layer coating solution was fed to a coating die so that 8.3 ml / m ^2.
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

3. Preparation of photothermographic material 1) Preparation of photothermographic material-101 On the surface opposite to the back surface on which the back layer-1 was applied, from the undercoat surface, the image forming layer coating solution-1, the intermediate layer coating solution, and the surface protection A layer of the first layer coating solution and the surface protective layer second layer coating solution were simultaneously applied by the slide bead coating method to prepare a sample of the photothermographic material. At this time, the coating solution for the image forming layer and the intermediate layer was adjusted to 31 ° C., the coating solution for the first surface protective layer was adjusted to 36 ° C., and the coating solution for the second surface protective layer was adjusted to 37 ° C.
The coating amount (g / m ² ) of each compound in the image forming layer is as follows.

Fatty acid silver 5.42
Pigment (C.I. Pigment Blue 60) 0.036
Polyhalogen compound-1 0.12
Polyhalogen compound-2 0.25
Phthalazine Compound-1 0.18
SBR latex 9.70
Reducing agent-1 0.40
Reducing agent-2 0.40
Hydrogen bonding compound-1 0.58
Development accelerator-1 0.02
Mercapto Compound-1 0.002
Mercapto compound-2 0.012
Silver halide (as Ag) 0.10

The coating and drying conditions are as follows.
The coating was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set to be 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating.
In the subsequent chilling zone, the coating liquid is cooled with a wind at a dry bulb temperature of 10 ° C. to 20 ° C., then transported in a non-contact manner, and dried at a dry bulb temperature of 23 ° C. to 45 ° C. It dried with the drying wind of 15 degreeC and the wet-bulb temperature of 15 to 21 degreeC.
After drying, the humidity was adjusted at 25 ° C. and humidity of 40% RH to 60% RH, and then the film surface was heated to 70 ° C. to 90 ° C. After heating, the film surface was cooled to 25 ° C.
The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the photosensitive layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.

2) Production of photothermographic material -102 to 115 Photothermographic material -102 to 115 was produced in the same manner as in production of photothermographic material -101, except that back layer-1 was changed to back layer-2 to 15. Was made.

3) Preparation of photothermographic material-201 The photothermographic material-101 was prepared in the same manner as the photothermographic material-1, except that the image forming layer coating solution-1 was changed to the image forming layer coating solution-2. Photothermographic material-2 was produced.
The coating amount (g / m ² ) of each compound in the image forming layer at this time is as follows.

Fatty acid silver 5.27
Pigment (C.I. Pigment Blue 60) 0.036
Polyhalogen compound-1 0.14
Polyhalogen compound-2 0.28
Phthalazine Compound-1 0.18
SBR latex 9.43
Reducing agent-2 0.77
Hydrogen bonding compound-1 0.28
Development accelerator-1 0.019
Development accelerator-2 0.016
Color tone adjusting agent-1 0.006
Mercapto compound-2 0.003
Silver halide (as Ag) 0.13

4) Preparation of photothermographic material -202 to 215 Photothermographic material -202 to 215 was prepared in the same manner as photothermographic material -201 except that back layer-1 was changed to back layer-2 to 15. Was made.

  The chemical structures of the compounds used in the examples of the present invention are shown below.

4). Evaluation of photographic performance 1) Preparation The obtained sample was cut into half-cut size (43 cm length x 35 cm width), packaged in the following packaging materials in an environment of 25 ° C. and 65% RH, and stored at room temperature for 2 weeks. The following evaluation was performed.
<Packaging materials>
PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% by mass of carbon:
Oxygen permeability: 0.02 ml / atm · m ² · 25 ° C · day;
Moisture permeability: 0.10 g / atm · m ² · 25 ° C · day.

2) Exposure / development of photosensitive material Photothermographic materials-101 to 115 are exposed and thermally developed at Fuji Medical Dry Laser Imager FM-DPL (with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB)) (112 ° C.-119). A total of 24 seconds was set with four panel heaters set to ℃ −121 ℃ −121 ℃, and the obtained image was evaluated by a densitometer.
Photothermographic material-201 to 215 were exposed and heat developed with Fuji Medical Dry Laser Imager DRYPIX7000 (with a 660 nm semiconductor laser with a maximum output of 50 mW (IIIB)) (107 ° C-121 ° C-121 ° C) A total of 14 seconds with a panel heater), and the obtained image was evaluated with a densitometer.

3) Performance evaluation <Evaluation of transportability>
The photothermographic materials -101 to 115 and -201 to 215 are subjected to uniform exposure so that the density is 1.5, and 50,000 sheets are each in the above running state under the condition of 35 ° C. and 85% RH. The number of jammings due to poor conveyance was counted.
<Glossiness evaluation under forced storage conditions after treatment>
The gloss of the back surface of each sample after storing the sample after heat development treatment for 7 days under the condition of 50 ° C. and 80% RH was measured, and the difference was evaluated with respect to the value immediately after the processing. The glossiness was measured using a GLOSSMETER VG-2000 manufactured by Nippon Denshoku Industries Co., Ltd.
Glossiness reduction degree (%) = Glossiness after storage-Glossiness immediately after processing

4) Evaluation results The results are shown in Tables 2 and 3.

When the binder of the back surface protective layer contains a water-soluble polymer and a latex polymer having a glass transition temperature of −30 ° C. or more and 40 ° C. or less, the number of defective conveyance is extremely small, and glossiness after forced aging also occurs. There was no good photothermographic material. In particular, when a polymer latex having an I / O ratio of 0.3 or more and 1.0 or less was used, excellent results with less reduction in gloss were shown. Polymer latex having an I / O ratio of 0.5 or more and 0.9 or less showed more excellent results.
The two types of used image recording apparatuses, Fuji Medical Dry Laser Imager FM-DPL and DRYPIX 7000, have a surface on the surface side having an image forming layer in contact with a driving roller and a surface on the side having a back layer. The film was brought into contact with a plate heater for thermal development. Even when an image was formed by such a method, the transportability was good and the obtained image was also good.

Example 2
1) Preparation of photothermographic material Gelatin and fluorine compound B used in the back surface protective layers of photothermographic materials -101 and 107 prepared in Example 1 were converted into polyvinyl alcohol and fluorine compounds shown in Table 4. Thus, photothermographic materials -301 to 311 were prepared. Gelatin was replaced with polyvinyl alcohol at an equal mass, and fluorine compound F-2 was replaced with the fluorine compound shown in Table 4 at an equimolar amount.

* PVA-205: Polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.)
2) Performance evaluation As shown by the results of the photothermographic materials -302 to 305, the use of the more preferable fluorine-based compounds described in the present application further improved the transportability and the glossiness.
Further, as shown in the results of the photothermographic materials 307 to 311, even when gelatin was changed to polyvinyl alcohol as the back surface protective layer binder, the same effect as gelatin was obtained.
The photothermographic materials according to the present invention all had a good coated surface.

1 is a schematic configuration diagram of an image recording apparatus equipped with a laser recording apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image recording device 16 Covering paper 36, 38, 40 Tray 37, 39, 41 Bar code reading window 43, 45, 47 Bar code reader 48, 50, 52 Single wafer mechanism 54 Image recording part 56 Roller 58 Plate 60 Thermal development Part 62 Roller 64a, b, c Plate heater 66 Drum 68 Cooling part 70 Discharge part F Film L Laser beam

Claims (15)

A surface having an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on at least one surface of the support, and the image forming layer on the support. A photothermographic material having at least one back layer and a back surface protective layer on the opposite surface side,
A photothermographic material, wherein the binder of the back surface protective layer contains a water-soluble polymer and a latex polymer having a glass transition temperature of from -30 ° C to 40 ° C.   2. The photothermographic material according to claim 1, wherein the latex polymer is contained in an amount of 5% by mass to 50% by mass with respect to all binders in the back surface protective layer.   The photothermographic material according to claim 2, wherein the latex polymer is contained in an amount of 15% by mass to 40% by mass with respect to all binders in the back surface protective layer.   The photothermographic material according to claim 1, wherein the latex polymer has a glass transition temperature of −30 ° C. or higher and 24 ° C. or lower.   The latex polymer is at least one polymer selected from the group consisting of acrylic, styrene, acrylic / styrene copolymer, styrene / butadiene copolymer, vinyl chloride, vinylidene chloride, and urethane. The photothermographic material according to claim 1, wherein the photothermographic material is a photothermographic material.   6. The photothermographic material according to claim 5, wherein the latex polymer is an acrylic latex polymer.   The photothermographic material according to claim 1, wherein the latex polymer has an I / O value of 0.1 or more and 1.0 or less.   8. The photothermographic material according to claim 7, wherein the I / O value is 0.5 or more and 0.9 or less.   The photothermographic material according to claim 1, wherein the latex polymer contains an anionic surfactant.   10. The photothermographic material according to claim 9, wherein the anionic surfactant is at least one selected from alkylbenzene sulfonates or sulfosuccinic acid diesters.   The photothermographic material according to claim 1, wherein the water-soluble polymer is gelatin.   11. The photothermographic sensor according to claim 1, wherein the water-soluble polymer is at least one selected from polyvinyl alcohols and acrylic acid-polyvinyl alcohol copolymer polymers. material.   13. The photothermographic material according to claim 1, comprising a fluorine compound having a fluorinated alkyl group having 2 or more carbon atoms and 13 or less fluorine atoms.   14. The photothermographic material according to claim 13, wherein the fluorine compound has a fluorinated alkyl group having 5 to 9 fluorine atoms.   15. An image forming method of a photothermographic material for forming an image with an image recording apparatus, wherein the image recording apparatus has a heat developing unit having a driving roller and a plate heater, and any one of claims 1 to 14. 2. The surface of the photothermographic material having the image forming layer according to claim 1 is brought into contact with the driving roller, and the surface of the photothermographic material having the back layer is brought into contact with the plate heater. An image forming method for a photothermographic material, wherein the development is performed by heating.

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