JP2005283933A - Method of manufacturing heat developable photosensitive material and heat developable photosensitive material manufactured by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a heat developable photosensitive material excellent in suitability to coating and ensuring little haze, and to provide a heat developable photosensitive material by the method. <P>SOLUTION: In the method of manufacturing a heat developable photosensitive material by coating at least one surface of a support with an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder and a side of the image forming layer remoter from the support with at least one non-photosensitive layer, (1) the non-photosensitive layer is formed from a coating liquid having a setting property and (2) a coating liquid for forming the image forming layer has pH 6.0-8.2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a photothermographic material and a photothermographic material produced thereby. In particular, a method for producing a water-based photothermographic material, a photothermographic material produced thereby, and a method for producing a high-quality photothermographic material having excellent coating properties and improved haze, and The present invention relates to a photothermographic material produced by the above.

  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, photosensitive heat for medical diagnosis and photographic technology that can be efficiently exposed by a laser image setter or 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 imaging systems using organic silver salts are disclosed in, for example, the specifications of U.S. Pat. “Thermally Processed Silver Systems” by Shely (Imaging Processes and Materials), 8th edition, Sturge V. (Walworth), A. Shepp edited, page 2, 1996). 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 a photosensitive 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 is blackened by an oxidation-reduction 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 area. Fuji Medical Dry Imager FM-DPL has been put on the market as a medical image forming system using a photothermographic material.

  A photothermographic material using an organic silver salt is manufactured by solvent coating, using an aqueous dispersion of polymer fine particles as a main binder, or using an aqueous solution of a water-soluble polymer. There is a method in which the liquid is applied and dried. Since the latter method does not require a process such as solvent recovery, the manufacturing equipment is simple, the environmental load is small, and it is advantageous for mass production.

However, the method for producing a water-based photothermographic material of the water-based coating method has a big problem that it is uniformly applied and dried because the image forming layer coating solution contains many components necessary for image formation. . In particular, when a photothermographic material is coated at a high speed to increase productivity and dried quickly to produce a photothermographic material, the haze may increase due to the disorder of the interface between the coating layers and the occurrence of liquid mixing between the layers. There were many problems such as the occurrence of unevenness on the coated surface due to fluctuations in the drying air. Further, when the binder of the image forming layer is a polymer latex, the problem is great because the coating solution does not have setability. In this application, “having setability” means “sol-gel conversion” that maintains fluidity at a coating liquid temperature above a certain temperature (usually about 30 ° C.) but loses fluidity at a temperature lower than that. When it has, it means that the applied liquid can form a state that is not substantially physically deformed even when an external pressure such as dry air is applied.
Such a haze causes unevenness of the coated surface when an image is formed. Therefore, particularly as a medical image forming material, it is a serious problem that affects diagnostic ability, and improvement is always required. Yes.

As an improvement means, it is known that a set polymer such as gelatin is used as a binder for the non-photosensitive layer on the upper layer of the image forming layer, and simultaneous coating with the image forming layer is performed (see Patent Document 1). There is also known a method in which a simultaneous multilayer coating is applied in a configuration in which an intermediate layer containing a water-soluble polymer and a polymer latex is provided between an image forming layer and a protective layer (see Patent Document 2). However, as described above, the image-forming layer coating solution contains many components necessary for image formation. Therefore, even if a layer other than the image-forming layer is devised, as an improvement means for uniformly coating and drying Was limited and still not enough. For example, a method of adding an additive chemical such as an acid or a crosslinking agent to a layer other than the image forming layer such as a protective layer is known (see Patent Document 3).
On the other hand, a method of applying by drying at a high temperature without using a set polymer is also known, but it is not sufficient for use as a medical image forming material (see Patent Document 3). .

JP-A-10-186571 Japanese Patent Laid-Open No. 11-288058 JP 2002-162712 A JP 2000-19678 A

  An object of the present invention is to provide a method for producing a photothermographic material having excellent coating properties and less haze, and a photothermographic material using the same. In particular, the present invention provides a method for producing a photothermographic material of an aqueous coating method and a photothermographic material produced thereby, and a method for producing a photothermographic material having excellent coating properties and less haze, and a photothermographic material produced thereby. It is.

  The above-described problems of the present invention have been solved by the following means.

<1> An image forming layer containing at least photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on at least one surface of the support, and at least one non-photosensitive layer on the side farther from the support A method for producing a photothermographic material to which a layer is applied,
1) The non-photosensitive layer is formed from a coating solution having setability,
2) A method for producing a photothermographic material, wherein the coating solution pH for forming the image forming layer is 6.0 or more and 8.2 or less.
<2> The method for producing a photothermographic material according to <1>, wherein the non-photosensitive layer coating solution has a pH of 4.0 or more and 6.0 or less.
<3> The method according to <1> or <2>, wherein the pH difference between the coating solution having the highest pH and the layer having the lowest pH in each layer coating solution is within 4 or less.
<4> The method for producing a photothermographic material according to any one of <1> to <3>, wherein the image forming layer and the image forming layer are applied by simultaneous multilayer coating.
<5> The method for producing a photothermographic material according to any one of <1> to <4>, wherein the image forming layer coating solution has a pH of 7.0 to 7.5.
<6> The method for producing a photothermographic material according to any one of <2> to <5>, wherein the non-photosensitive layer coating solution has a pH of 4.5 to 5.0. .
<7> The film surface pH of the surface having the image forming layer of the photothermographic material is 4.0 or more and 6.0 or less, wherein any one of <1> to <6> A method for producing a photothermographic material.

<8> The method for producing a photothermographic material according to <7>, wherein a film surface pH of the surface having the image forming layer of the photothermographic material is from 5.2 to 5.9.
<9> The method for producing a photothermographic material according to any one of <1> to <8>, which is applied with an aqueous solvent.
<10> The method for producing a photothermographic material according to <9>, wherein 50% by mass or more of the binder is a polymer latex.
<11> The photothermographic material according to <10>, wherein the polymer latex has a monomer component having an acid group in an amount of 1% by mass to 20% by mass.
<12> The photothermographic material according to <10> or <11>, wherein a glass transition point (Tg) of the polymer latex is from −10 ° C. to 70 ° C.
<13> A second non-photosensitive layer is provided between the image forming layer and the non-photosensitive layer, and 50% by mass or more of the binder of the second non-photosensitive layer is formed from a polymer latex. <1>-<12> The method for producing a photothermographic material according to any one of <1> to <12>.
<14> The photothermographic material according to any one of <1> to <13>, wherein the pH of the second non-photosensitive layer coating solution is 6.0 or more and 8.2 or less. Production method.
<15> The photothermographic material according to any one of <1> to <14>, wherein the pH of the second non-photosensitive layer coating solution is 7.0 or more and 7.5 or less. Production method.
<16> A photothermographic material produced by the production method according to any one of claims 1 to 15.

The method for producing a photothermographic material, which is obtained by applying multiple layers of coating solutions having different compositions at the same time (simultaneous multiple layers), is greatly improved in coating properties (coating surface) due to slight variations in the physical properties of each coating solution. Influence). Conventionally, it is often manufactured by an organic solvent coating method, and such knowledge is hardly useful for a manufacturing method of an aqueous coating method.
The present invention aims to establish a production method for stably producing a water-based photothermographic material, and as a result of diligent efforts to analyze the physical properties of the coating solution affecting coating failures and develop countermeasures, It was found by paying attention to the pH of the coating solution. Further, the invention <1> has been found for the first time when a non-photosensitive layer having setability is used, which is solved by maintaining the pH of the coating solution for the image forming layer at 6.0 or more and 8.2 or less. It came to. Moreover, it discovered that it was preferable to set the coating property non-photosensitive layer coating liquid pH to 4.0 or more and 6.0 or less. Conventionally, an aqueous coating type image forming layer coating solution is generally applied with a high alkalinity of pH 8.3 or more in order to maintain the stability of the image forming layer coating solution. Further, the acidity was lower than that of the set non-photosensitive layer coating solution pH 4. As a result of the examination, it was found that the pH gap between the image forming layer coating solution and the set non-photosensitive layer coating solution is large, and this is one of the major factors of production instability when simultaneous multilayer coating is performed. As a result, the inventions <2> to <7> have been reached. The invention <8> is based on the finding of a more preferable non-photosensitive organic silver salt dispersion in the image forming layer coating solution described in <1>. The other invention is due to the discovery of conditions that can best exhibit the effects of the present application. The invention <13> is a photothermographic material produced according to the production conditions of the present invention.

  According to the present invention, there are provided a method for producing a photothermographic material having excellent coating properties and less haze, and a photothermographic material using the same. In particular, there are provided a method for producing a photothermographic material of an aqueous coating system and a photothermographic material produced thereby, and a method for producing a photothermographic material having excellent coating properties and less haze, and a photothermographic material produced thereby. .

The present invention is described in detail below.
1. Photothermographic material and method for producing the same

The photothermographic material of the present invention has an image forming layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support. The photothermographic material of the present invention may preferably have a surface protective layer on the image forming layer, or a back layer or a back protective layer on the opposite surface. The photothermographic material of the present invention may be a double-sided photothermographic material having image forming layers on both sides of a support or a single-sided photothermographic material having only one side.
The configuration of each layer and preferred components thereof will be described in detail.

1. Layer Structure Usually, a photothermographic material has an image forming layer composed of one or more layers on a support. In addition to the image forming layer, it has a non-photosensitive layer.
The non-photosensitive layer comprises: (a) a surface protective layer provided on the image forming layer (on the side farther from the support), (b) between the plurality of image forming layers and between the image forming layer and the surface protective layer. (C) an undercoat layer provided between the image forming layer and the support, and (d) a back layer provided on the opposite side of the image forming layer. These layers may be each independently a single layer or a plurality of layers.
The photothermographic material of the present invention has an image forming layer and at least one non-photosensitive layer as essential constituent elements, and one of the non-photosensitive layers is the surface protective layer of (a) and is supported. The layer farthest from the body.
Further, in the present invention, it is preferable to provide a first non-photosensitive layer and a second non-photosensitive layer as the surface protective layer (a) or the intermediate layer (b). The first non-photosensitive layer preferably contains a binder that can be gelled by a decrease in temperature. The second non-photosensitive layer preferably contains 50% by mass or more of an aqueous dispersion of a hydrophobic polymer as a binder.

1-1. PH of coating solution
The photothermographic material of the present invention is produced by adjusting the pH of the image forming layer coating solution to 6.0 or more and 8.2 or less, preferably 7.0 to 7.5 or less. In a preferred embodiment, the first non-photosensitive layer coating solution has a pH of 4.0 or more and 6.0 or less, more preferably 4.5 or more and 5.0 or less.
Further, it is more preferable that the pH difference between the coating solution having the highest pH and the coating solution having the lowest pH in each layer coating solution is 4 or less. (1) Addition of acid / alkali to the coating solution (2) It can carry out by methods, such as pH adjustment of the various additive chemical | medical agents for preparing a coating liquid, A well-known acid and alkali can be used as a pH adjuster. Specifically, a non-volatile acid such as an organic acid such as a phthalic acid derivative or sulfuric acid, or a volatile acid such as acetic acid or hydrochloric acid is used as the acid. However, from the viewpoint of reducing the film surface pH. Nonvolatile acids are preferred. Further, as the base, a non-volatile base such as sodium hydroxide, potassium hydroxide or lithium hydroxide, or a volatile base such as ammonia is used. However, from the viewpoint of reducing the film surface pH, a volatile base is used. preferable. 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.
When adding water or water-insoluble materials to a dispersion of acid / alkali, the dispersion stability may be destroyed and aggregates may be generated. Thus, it is preferable to suppress as much as possible the occurrence of aggregation associated with mixing during preparation. In particular, since the binder is used in a large amount in each coating solution, it is preferable to adjust the pH of the coating solution within the range of the present invention by adjusting the pH in advance.

1-2. Membrane surface pH
The photothermographic material of the present invention preferably has a film surface pH of 4.0 or more and 6.0 or less, more preferably 5.2 or more and 5.9 or less before heat development processing. The adjustment of the film surface pH is preferably performed from the viewpoint of reducing the film surface pH by using the organic acid such as the phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia. In addition, the measuring method of film surface pH is described in paragraph number 0123 of Unexamined-Japanese-Patent No. 2000-284399.

1-3. Other Layers In the present invention, a layer acting as an optical filter can be provided, and is provided as the layer (a) or (b) of the non-photosensitive layer. The antihalation layer is provided on the photosensitive material as the layer (c) or (d).

  The photothermographic material of the present invention may be a single-sided type having an image forming layer only on one side of a support, or a double-sided type having image forming layers on both sides of a support. In the case of the double-sided type, it is sufficient that an outermost layer containing an aqueous dispersion of a polymer having a crosslinked structure is provided on at least one side, but preferably an aqueous dispersion of a polymer having a crosslinked structure on both sides is provided. This is a case where the outermost layer to be contained is provided.

In the case of a single-sided photothermographic material, it is preferable to have a back layer on the side opposite to the side having the image forming layer with respect to the support (hereinafter referred to as the back side).
The single-sided photothermographic material in the invention can be preferably used as an X-ray photosensitive material for mammography. In the single-sided photothermographic material used for this purpose, it is important to design the contrast of the obtained image within an appropriate range.
With regard to preferable constitutional requirements as an X-ray photosensitive material for mammography, JP-A-5-45807, JP-A-10-62881, JP-A-10-54900, and JP-A-11-109564 can be referred to. .

  The double-sided photothermographic material can be preferably used in an image forming method for recording an X-ray image using an X-ray intensifying screen. The photosensitive material by X-ray exposure is suitably used for medical diagnosis.

  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 multi-dye multicolor photosensitive photothermographic materials, each emulsion layer is generally functional or non-functional between each photosensitive layer as described in US Pat. No. 4,460,681. By using different barrier layers, they are distinguished from each other and held.

2. Component (1) First Non-Photosensitive Layer of Each Layer In the present invention, it is preferable to provide a first non-photosensitive layer. In the present invention, the first non-photosensitive layer is provided on the image forming layer surface side, and is provided between the outermost layer and the image forming layer. The first non-photosensitive layer preferably contains a binder that can be gelled by a decrease in temperature.
The binder that can be gelled means a water-soluble polymer derived from animal protein as shown below, or a water-soluble polymer or hydrophobic polymer not derived from animal protein to which a gelling agent is added.
Since the fluidity of the layer formed by coating is lost by gelling, the surface on the image forming layer side is less susceptible to wind for drying in the drying step after the coating step. A photothermographic material having a uniform coated surface can be obtained. Here, at the time of application, it is important that the coating solution is not gelled. Considering the ease of work, the coating liquid has fluidity at the time of coating, and gelates and loses fluidity at the time before entering the drying process after coating. The viscosity of the coating solution during coating is preferably 5 mPa · s or more and 200 mPa · s or less, and more preferably 10 mPa · s or more and 100 mPa · s or less.

  In the present invention, an aqueous solvent is used as the solvent of the coating solution. The aqueous solvent is a mixture of water or water with 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, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate and dimethylformamide.

  Although it is difficult to measure the viscosity of the formed layer at the time before entering the drying step after coating (gelation at this time), it is generally not less than 200 mPa · s and not more than 5000 mPa · s, preferably 500 mPa -It is estimated that it is about s or more and 5000 mPa * s or less.

  The temperature for gelation is not particularly limited, but the gelling temperature is preferably around room temperature in consideration of the work efficiency of coating. Because it is a temperature at which the fluidity of the coating liquid can be easily increased so that it can be easily applied, and the fluidity can be maintained (that is, the elevated temperature is easily maintained). This is because the temperature is such that it can be easily cooled to lose the fluidity of the formed layer after coating. Specifically, the gelation temperature is preferably 0 ° C. or higher and 40 ° C. or lower, more preferably 0 ° C. or higher and 35 ° C. or lower.

  If the temperature of the coating solution at the time of application is set higher than the gelation temperature, there is no particular limitation, and if the cooling temperature after coating and before the drying step is set lower than the gelation temperature, there is no particular limitation. No. However, if the difference between the temperature of the coating liquid and the cooling temperature is set to be small, gelation starts during the coating process, resulting in problems such as being unable to apply uniformly. Further, if the temperature of the coating solution is set too high in order to increase these temperature differences, problems such as evaporation of the solvent of the coating solution and change in viscosity occur. Therefore, the temperature difference is preferably set to 5 ° C. or more and 50 ° C. or less, more preferably 10 ° C. or more and 40 ° C. or less.

  The first non-photosensitive layer is not particularly limited as long as it is provided on the image forming layer surface side with respect to the support and is provided between the image forming layer and the outermost layer, but preferably, the first non-photosensitive layer is described below. 2 between the non-photosensitive intermediate layer and the outermost layer. In particular, the layer adjacent to the outermost layer is preferable from the viewpoint of suppressing unevenness of the film surface during drying by wind. That is, as a preferable layer configuration, the first non-photosensitive layer, the second non-photosensitive layer, and the image forming layer are sequentially formed from the outermost layer. Layers other than these may be provided.

(Description of water-soluble polymer derived from animal protein)
In the present invention, the polymer derived from animal protein refers to a natural or chemically modified water-soluble polymer such as glue, casein, gelatin, egg white and the like.
Gelatin is preferred, and acid-treated gelatin and alkali-treated gelatin (such as lime treatment) are available 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).
The gelatin aqueous solution becomes sol when heated to a temperature of 30 ° C. or higher, and gels and loses fluidity when lowered to a temperature lower than that. Since such a sol-gel change occurs reversibly with temperature, the gelatin aqueous solution which is a coating solution has a set property of losing fluidity when cooled to a temperature lower than 30 ° C.
The water-soluble polymer derived from animal protein can be used together with the following water-soluble polymer not derived from animal protein and / or hydrophobic polymer.
The content of the animal protein-derived water-soluble polymer in the coating solution is 1% by mass or more and 20% by mass or less, and preferably 2% by mass or more and 12% by mass or less with respect to the entire coating solution.

(Description of water-soluble polymer not derived from animal protein)
The water-soluble polymer not derived from animal protein in the present invention is a natural polymer (polysaccharide, microbial, animal) other than animal protein such as gelatin, semi-synthetic polymer (cellulose, starch, alginic acid). ) And synthetic polymers (vinyl-based, etc.), which are 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. Since a water-soluble polymer not derived from animal protein does not have setability, a water-soluble polymer not derived from animal protein is used together with a gelling agent described later in order to use it in a layer adjacent to the outermost layer.

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 substances, 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.), K polymer as KL-118, KL-318, KL-506, KM-118T, KM-618 (all are trade names manufactured by Kuraray Co., Ltd.), and M polymer as M-115 (manufactured by Kuraray Co., Ltd.) (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. It is preferable that the addition amount of boric acid is 0.01 mass% or more and 40 mass% or less with respect to polyvinyl alcohol.

Polyvinyl alcohol has been described in the above-mentioned document “Poval” that the degree of crystallinity is improved by heat treatment and the water resistance is improved. Since water resistance improves by processing, it is particularly preferable for the present invention among water-soluble polymers.
In order to further improve the water resistance, it is preferable to add a water-proofing 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), 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% by mass to 40% by mass with respect to polyvinyl alcohol.

2) Other water-soluble polymers not derived from animal proteins Examples of the water-soluble polymers not derived from animal proteins 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 the cellulose-based polymer, ethyl cellulose (ICF Cellofas WLD, etc.), carboxymethyl cellulose (Daicel CMC, etc.), hydroxyethyl cellulose (Daicel HEC, etc.), hydroxypropyl cellulose (Aqualon Klucel, etc.), methyl cellulose (Such as Viscontran manufactured by Henkel), nitrocellulose (such as Isopropyl Wet manufactured by Hercules), and cationized cellulose (such as Crodacel QM manufactured by Croda). 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 polysodium 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 polymer 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 a copolymer or copolymers of these vinyl monomers or other vinyl monomers (for example, sodium methacrylate, ammonium methacrylate, Sumika Gel 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.

  The concentration in the coating solution is preferably adjusted so that the viscosity becomes a value suitable for simultaneous multilayer coating when added, but is not particularly limited. In general, the concentration in the liquid is 0.01% by mass or more and 30% by mass or less, more preferably 0.05% by mass or more and 20% by mass or less, and particularly preferably 0.1% by mass or more and 10% by mass or less. is there. The viscosity obtained by these is preferably 1 mPa · s or more and 200 mPa · s or less, more preferably 5 mPa · s or more and 100 mPa · s or less as an increase from the initial viscosity. In the measurement, values measured at 25 ° C. with a B-type rotational viscometer are shown. The glass transition temperature of the water-soluble polymer preferably used in the present invention is not particularly limited, but is preferably 60 ° C. or higher and 220 ° C. or lower from the viewpoint of brittleness such as generation of a belt mark by heat development and dust during processing. More preferably, it is 70 degreeC or more and 200 degrees C or less. Furthermore, 80 degreeC or more and 180 degrees C or less are preferable. Most preferably, it is 90 ° C or higher and 170 ° C or lower.

In addition to the water-soluble polymer not derived from animal protein in the present invention, a polymer dispersible in an aqueous solvent may be used in combination.
Suitable water-dispersible polymers include synthetic resins, polymers and copolymers, and other film-forming media such as cellulose acetates, cellulose acetate butyrate, poly (methyl methacrylic acid), poly (vinyl chloride) , Poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, poly (vinyl acetal) s (eg, poly (vinyl formal) and Poly (vinyl butyral)), poly (ester), poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), poly ( Olefins), cellulose esters, poly (amides) Kill.
Preferred latexes are described in the latex polymer description below. These latexes may be mixed in an amount of 1% to 70% by weight, preferably 5% to 50% by weight, based on a water-soluble polymer not derived from animal protein.

(Description of gelling agent)
The gelling agent in the present invention is added to the water-soluble polymer aqueous solution or the hydrophobic polymer latex aqueous solution not derived from animal protein in the present invention, and a substance that causes gelation of the solution when cooled, or a gelation promoting substance It is a substance that causes gelation when used in combination. By causing gelation, the fluidity is significantly reduced.

  Specific examples of the gelling agent include the following water-soluble polysaccharides. That is, agar, κ-carrageenan, ι-carrageenan, alginic acid, alginate, agarose, furceleran, gellan gum, glucono delta lactone, azotobacter vineland gum, xanthan gum, pectin, guar gum, locust bean gum, tara gum, cassia gum, gluco It is at least one selected from mannan, gum tragacanth, karaya gum, pullulan, gum arabic, arabinogalactan, dextran, carboxymethylcellulose sodium salt, methylcellulose, silium sheet gum, starch, chitin, chitosan and curdlan.

  Examples of the substance that gels by cooling after being heated and dissolved include substances such as agar, carrageenan, and julan gum.

  Among these gelling agents, κ-carrageenan (eg: K-9F, manufactured by Taisho Co., Ltd .: Nitta Gelatin Co., Ltd .: K-15: K-21-24, I— 3), iota-carrageenan and agar are mentioned, and κ-carrageenan is particularly preferred.

  The gelling agent is 0.01% by mass or more and 10.0% by mass or less, preferably 0.02% by mass or more and 5.0% by mass or less, more preferably 0.05% by mass or more and 2.% by mass or more with respect to the binder polymer. It is preferable to use 0% by mass or less.

  The gelling agent is preferably used together with a gelling accelerator. The gelation accelerator in the present invention is a compound that promotes gelation by contact with the gelling agent, and its function is exhibited by a specific combination with the gelling agent. In the present invention, the following combinations can be used as the combination of the gelling agent and the gelation accelerator.

  1) Alkali metal ions such as potassium as gelation accelerators, or alkaline earth metal ions such as calcium and magnesium; Combination of salt etc.

  2) A combination of boric acid or other boron compounds as a gelling accelerator and guar gum, locust bean gum, tara gum, cassia gum or the like as a gelling agent.

  3) A combination of an acid or an alkali as a gelling accelerator and an alginate, glucomannan, pectin, chitin, chitosan, curdlan or the like as a gelling agent.

  4) A water-soluble polysaccharide that reacts with a gelling agent to form a gel is used as a gelation accelerator. Specifically, a combination using xanthan gum as the gelling agent, using cassia gum as the gelling agent, using carrageenan as the gelling agent, and using locust bean gum as the gelling agent can be exemplified.

The following a) -g) can be illustrated as a specific example of the combination of these gelling agents and gelation accelerators.
a) Combination of κ-carrageenan and potassium b) Combination of ι-carrageenan and calcium c) Combination of ro-methoxyl pectin and calcium d) Combination of sodium alginate and calcium e) Combination of gellan gum and calcium f) Combination of gellan gum and acid g) Combination of Locust Bingham and Xanthan Gum Such a combination may be used in combination.

  These gelation accelerators may be added to the same layer to which the gelling agent is added, but it is preferable to add them to different layers and act. More preferably, it is added to a layer not directly adjacent to the layer to which the gelling agent is added. That is, it is more preferable to have a layer containing neither a gelling agent nor a gelling accelerator between a layer containing a gelling agent and a layer containing a gelling accelerator.

  The gelling accelerator is used in an amount of 0.1 to 200% by mass, preferably 1.0 to 100% by mass, based on the gelling agent.

  The content of the binder that can be gelled by a temperature decrease is preferably 3% by mass or more and 60% by mass or less, and more preferably 5% by mass or more and 50% by mass or less with respect to the entire outermost layer coating solution.

(Amount of application)
The coating amount of the outermost hydrophobic polymer is preferably 0.1 g / m ² or more and 10 g / m ² or less, more preferably 0.2 g / m ² or more and 5 g / m ² or less, most preferably 0. .5g / ^{m 2} or more 3.0 g / ^{m 2} or less.

(3) Second non-photosensitive layer In the present invention, it is preferable to provide a second non-photosensitive layer. The binder of the second non-photosensitive layer contains 50% by mass or more of an aqueous dispersion of a hydrophobic polymer. Preferably, they are 80 mass% or more and 100 mass% or less, More preferably, they are 90 mass% or more and 100 mass% or less. When the amount is less than 50% by mass, the effect of improving the image storage stability is reduced, which is not preferable.
In the present invention, an aqueous dispersion of a hydrophobic polymer is a latex in which fine particles of a hydrophobic polymer insoluble in an aqueous solvent are dispersed, a polymer molecule dispersed in a molecular state or micelle, etc. Any of them may be used, but latex dispersed particles are more preferable.
The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. 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, the hydrophobic polymer is not particularly limited, but 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) 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. The molecular weight of these polymers is 5,000 to 1,000,000, preferably 10,000 to 200,000 in terms of number average molecular weight. 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.
The Tg of the hydrophobic polymer of the present invention is preferably in the range of −30 ° C. or more and 70 ° C. or less. More preferably, it is -10 degreeC or more and 35 degrees C or less, Most preferably, it is 0 degreeC or more and 35 degrees C or less. When Tg is lower than −30 ° C., the film formability is excellent, but the film has weak heat resistance strength. When it is higher than 70 ° C., the polymer has excellent heat resistance strength, but the film formability is poor. Since it becomes a sufficient film | membrane, it is not preferable. However, in order to obtain such a Tg, it is also possible to prepare using two or more kinds of polymers. That is, even if the polymer has a Tg outside the above range, the mass average Tg is preferably within the above range.

  The hydrophobic polymer preferably has an I / O value of 0.025 or more and 0.5 or less. More preferably, it is 0.05 or more and 0.3 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. When the I / O value is lower than 0.025, the affinity with an aqueous solvent is poor, and it becomes difficult to apply with an aqueous coating solution. When the I / O value is higher than 0.5, the resulting film is hydrophilic. It is not preferable because the film becomes a thick film, affects the photographic properties with respect to humidity, and remarkably deteriorates photographic performance. The I / O value 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. When the distance between the boiling point curve of the straight-chain paraffin and the straight-chain paraffin curve is about 5 ° C., the temperature is about 100 ° C. Therefore, the influence of one hydroxyl group is set to 100 as a numerical value. On the other hand, the organic value is based on the methylene group in the molecule as the unit, and can be measured by the number of carbon atoms that represent the methylene group. 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 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.

More preferred as the binder for the non-photosensitive intermediate layer in the present invention is a polymer obtained by copolymerizing the monomer represented by the general formula (M).
The content of the polymer obtained by copolymerizing the monomer represented by the general formula (M) in the binder in the non-photosensitive intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more and 100% by mass or less. More preferably, it is 90 mass% or more and 100 mass% or less.

General formula (M)
CH ₂ = CR ⁰¹ -CR ⁰² = CH ₂
In the formula, R ⁰¹ and R ⁰² are each independently a group selected from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a cyano group.

Preferred alkyl groups for R ⁰¹ and R ⁰² are each independently an alkyl group having 1 to 4 carbon atoms, and more preferably an alkyl group having 1 to 2 carbon atoms. As the halogen atom, a fluorine atom, a chlorine atom or a bromine atom is preferable, and a chlorine atom is more preferable.
As R ⁰¹ and R ⁰² , particularly preferably, both are hydrogen atoms, or one is a hydrogen atom and the other is a methyl group or a chlorine atom.

  Specific examples of the monomer represented by the general formula (M) in the present invention include 1,3-butadiene, 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 2,3. -Dimethyl-1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-fluoro-1,3-butadiene, 2 , 3-dichloro-1,3-butadiene and 2-cyano-1,3-butadiene.

In the present invention, the other monomer that can be copolymerized with the monomer represented by formula (M) is not particularly limited, and any monomer that can be polymerized by a normal radical polymerization or ionic polymerization method is preferably used. be able to.
The monomers that can be preferably used can be selected independently and freely in combination from the monomer groups (a) to (j) shown below.

-Monomer group (a)-(j)-
(A) Conjugated dienes: 1,3-butadiene, 1,3-pentadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl-1,3 -Butadiene, 1-bromo-1,3-butadiene, 1-chloro-1,3-butadiene, 1,1,2-trichloro-1,3-butadiene, cyclopentadiene and the like.
(B) Olefin: ethylene, propylene, vinyl chloride, vinylidene chloride, 6-hydroxy-1-hexene, 4-pentenoic acid, methyl 8-nonenoate, vinylsulfonic acid, trimethylvinylsilane, trimethoxyvinylsilane, 1,4- Divinylcyclohexane, 1,2,5-trivinylcyclohexane, etc. (c) α, β-unsaturated carboxylic acid and its salts: acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, itaconic acid Potassium and the like.

  (D) α, β-unsaturated carboxylic acid esters: alkyl acrylates (for example, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate) A substituted alkyl acrylate (for example, 2-chloroethyl acrylate, benzyl acrylate, 2-cyanoethyl acrylate, etc.), an alkyl methacrylate (for example, methyl methacrylate). Acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, etc.), substituted alkyl methacrylate (for example, 2-hydroxyethyl methacrylate, glycidyl methacrylate). Glycerin monomethacrylate, 2-acetoxyethyl methacrylate, tetrahydrofurfuryl methacrylate Acrylate, 2-methoxyethyl methacrylate, polypropylene glycol monomethacrylate (polyoxypropylene added mole number = 2 to 100), 3-N, N-dimethylaminopropyl methacrylate Chloro-3-N, N, N-trimethylammoniopropyl methacrylate, 2-carboxyethyl methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl methacrylate, 3- Trimethoxysilylpropyl methacrylate, aryl methacrylate, 2-isocyanatoethyl methacrylate, etc.) and unsaturated dicarboxylic acid derivatives (eg, monobutyl maleate, dimethyl maleate, monomethyl itaconate, itaconic acid) Dibutyl, etc.), polyfunctional esters (for example, ethylene glycol diacrylate) Ethylene glycol dimethacrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylol Ethane triacrylate, dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate, 1,2,4-cyclohexanetetramethacrylate, etc.).

  (E) Amides of β-unsaturated carboxylic acid: for example, acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-methyl-N-hydroxyethylmethacrylamide, N-tertbutylacrylamide, N- tert-octylmethacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, N-acryloylmorpholine, diacetoneacrylamide, itaconic acid diamide, N-methylmaleimide, 2-acrylamido-methyl Propanesulfonic acid, methylenebisacrylamide, dimethacryloylpiperazine, etc.

(F) Unsaturated nitriles: acrylonitrile, methacrylonitrile and the like.
(G) Styrene and its derivatives: styrene, vinyltoluene, p-tertbutylstyrene, vinylbenzoic acid, methyl vinylbenzoate, α-methylstyrene, p-chloromethylstyrene, vinylnaphthalene, p-hydroxymethylstyrene, p- Styrene sulfonic acid sodium salt, p-styrene sulfinic acid potassium salt, p-aminomethylstyrene, 1,4-divinylbenzene and the like.
(H) Vinyl ethers: methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether and the like.
(I) Vinyl esters: vinyl acetate, vinyl propionate, vinyl benzoate, vinyl salicylate, vinyl chloroacetate, and the like.
(J) Other polymerizable monomers: N-vinylimidazole, 4-vinylpyridine, N-vinylpyrrolidone, 2-vinyloxazoline, 2-isopropenyloxazoline, divinylsulfone, and the like.

Preference is given to copolymerization with styrene, acrylic acid and / or acrylic esters. Furthermore, a copolymer having styrene and acrylic acid as monomer units is preferable because the finished hydrophobic polymer can be used as an aqueous dispersion having good dispersion stability.
The copolymerization ratio of the monomer represented by the general formula (M) and the other monomer is not particularly limited, but preferably the monomer represented by the general formula (M) is 10% by mass or more and 70% by mass or less. The copolymerization is preferably 15% by mass to 65% by mass, more preferably 20% by mass to 60% by mass.

  Specific examples of preferred hydrophobic polymers 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.

LP-1; latex of -MMA (55) -EA (42) -MAA (3)-(Tg 39 ° C., I / O value 0.636)
LP-2; -MMA (47) -EA (50) -MAA (3) -latex (Tg 29 ° C., I / O value 0.636)
LP-3; Latex of -MMA (17) -EA (80) -MAA (3)-(Tg-4 ° C, I / O value 0.636)
LP-4; Latex of -EA (97) -MAA (3)-(Tg-20 ° C, I / O value 0.636)
LP-5; Latex of -EA (97) -AA (3)-(Tg-21 ° C, I / O value 0.648)
LP-6; Latex of -EA (90) -AA (10)-(Tg-15 ° C, I / O value 0.761)
LP-7; -MMA (50) -2EHA (35) -St (10) -AA (5) -latex (Tg 34 ° C., I / O value 0.461)
LP-8; Latex of -MMA (30) -2EHA (55) -St (10) -AA (5)-(Tg 3 ° C., I / O value 0.398)
LP-9; latex of MMA (10) -2EHA (75) -St (10) -AA (5)-(Tg-23 ° C, I / O value 0.339)
LP-10; latex of -MMA (60) -BA (36) -AA (4)-(Tg 29 ° C., I / O value 0.581)
LP-11; latex of -MMA (40) -BA (56) -AA (4)-(Tg-2 ° C, I / O value 0.545)
LP-12; latex of -MMA (25) -BA (71) -AA (4)-(Tg-22 ° C, I / O value 0.519)
LP-13; -MMA (42) -BA (56) -AA (2)-(molecular weight 540000, Tg-4 ° C, I / O value 0.530)
LP-14; Latex of -St (40) -BA (55) -AA (5)-(Tg-2 ° C, I / O value 0.319)
LP-15; Latex of -St (25) -BA (70) -AA (5)-(Tg-21 ° C, I / O value 0.377)

LP-16; Latex of -MMA (58) -St (8) -BA (32) -AA (2)-(Tg 34 ° C., I / O value 0.515)
LP-17; -MMA (50)-St (8)-BA (35)-HEMA (5)-AA (2)-latex (Tg 27 ° C, I / O value 0.542)
LP-18; Latex of -MMA (42) -St (8) -BA (43) -HEMA (5) -AA (2)-(Tg 14 ° C., I / O value 0.528)
LP-19; -MMA (24) -St (8) -BA (61) -HEMA (5) -AA (2)-latex (Tg-12 ° C, I / O value 0.498)
LP-20; Latex of -MMA (48) -St (8) -BA (27) -HEMA (15) -AA (2)-(Tg 39 ° C., I / O value 0.619)
LP-21; Latex of -EA (96) -AA (4)-(Tg-21 ° C, I / O value 0.664)
LP-22; Latex of -EA (46) -MA (50) -AA (4)-(Tg-4 ° C, I / O value 0.739)
LP-23; -EA (80) -HEMA (16) -AA (4)-latex (Tg-9 ° C, I / O value 0.775)
LP-24; Latex of -EA (86) -HEMA (10) -AA (4)-(Tg-13 ° C, I / O value 0.733)
LP-25; Latex of -St (45) -Bu (52) -MAA (3)-(Tg-26 ° C, I / O value 0.990)
LP-26; Latex of -St (55) -Bu (42) -MAA (3)-(Tg-9 ° C, I / O value 0.105)
LP-27; Latex of -St (60) -Bu (37) -MAA (3)-(Tg 1 ° C, I / O value 0.109)
LP-28; latex of -St (68) -Bu (29) -MAA (3)-(Tg 17 ° C, I / O value 0.114)
LP-29; -St (75) -Bu (22) -MAA (3)-latex (Tg 34 ° C., I / O value 0.119)
LP-30; Latex of -St (40) -BA (58) -AA (2)-(Tg-8.1 ° C, I / O value 0.293)

LP-31; Latex of -St (40) -BA (58) -MAA (2)-(Tg-7.1 ° C, I / O value 0.287)
LP-32; -St (57.2) -BA (27.7) -MMA (8.7) -HEMA (4.8) -AA (1.6) latex (Tg 37.8 ° C, I / O Value 0.269)
LP-33; -St (49.6) -BA (40) -MMA (4) -HEMA (4.8) -AA (1.6) latex (Tg 16.7 ° C, I / O value 0.289) )
LP-34; Latex of -St (80) -2EHA (18) -AA (2)-(Tg 59.7 ° C, I / O value 0.148)
LP-35; -St (70) -2EHA (28) -AA (2)-latex (Tg 40.9 ° C, I / O value 0.164)
LP-36; Latex of -St (10) -2EHA (38) -MMA (50) -AA (2)-(Tg 25.6 ° C, I / O value 0.427)
LP-37; Latex of -St (10) -2EHA (58) -MMA (30) -AA (2)-(Tg-3.9 ° C, I / O value 0.365)
LP-38; Latex of -St (10) -2EHA (78) -MMA (10) -AA (2)-(Tg-28.1 ° C, I / O value 0.308)
LP-39; Latex of -St (20) -2EHA (68) -MMA (10) -AA (2)-(Tg-16.8 ° C, I / O value 0.285)
LP-40; Latex of -St (30) -2EHA (58) -MMA (10) -AA (2)-(Tg-4.4 ° C, I / O value 0.263)
LP-41; -MMA (45) -BA (52) -Itaconic acid (3) -latex (Tg 4 ° C., I / O value 0.560)

LP-42; a latex of -St (62) -Bu (35) -MAA (3)-(crosslinkability, Tg 5 ° C)
LP-43; Latex of -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C.)
LP-44; latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C)
LP-45; Latex of -St (70) -Bu (27) -IA (3)-(crosslinkability, Tg 23 ° C.)
LP-46; -St (75) -Bu (24) -AA (1)-latex (crosslinkable, Tg 29 ° C)
LP-47; a latex of -St (60) -Bu (35) -DVB (3) -MAA (2)-(crosslinkability, Tg 6 ° C)
LP-48; -St (70) -Bu (25) -DVB (2) -AA (3)-latex (crosslinkable, Tg 26 ° C.)
Latex of LP-49; -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
Latex of LP-50; -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
LP-51; Latex of -St (61.3) -isoprene (35.5) -AA (3)-(crosslinkability, Tg 17 ° C.)
LP-52; Latex of -St (67) -isoprene (28) -Bu (2) -AA (3)-(crosslinkability, Tg 27 ° C.)

  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, DVB; IA; Itaconic acid.

  The aqueous dispersion of the hydrophobic polymer is 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.), etc. Examples of poly (esters) include poly (urethane) such as FINETEX ES650, 611, 675, 850 (above, Dainippon Ink Chemical Co., Ltd.), WD-size, WMS (above, Eastman Chemical). Examples of rubbers include HYDRAN AP10, 20, 30, 40 (above, manufactured by Dainippon Ink Chemical Co., Ltd.), and examples of rubbers include LACSTAR 7310K, 3307B, 4700H, 7132C (above, Dainippon Ink Chemical Co., Ltd.). (Made by Co., Ltd.), Nipol Lx416, 410, 438C, 2507 As examples of poly (vinyl chloride) such as G351 and G576 (above, manufactured by Nippon Zeon Co., Ltd.), examples of poly (vinylidene chloride) such as L502, L513 (above Examples of poly (olefin) s such as Asahi Kasei Kogyo Co., Ltd. include Chemipearl S120 and SA100 (above, Mitsui Chemicals, Inc.).

As the latex of styrene-butadiene copolymer preferably used in the present invention, the above-mentioned LP-42 to LP-50, commercially available products LACSTAR-3307B and 7132C (above, manufactured by Dainippon Ink & Chemicals, Inc.) , Nipol Lx416 (manufactured by Zeon Corporation) and the like.
Examples of the latex of the styrene-isoprene copolymer include the aforementioned LP-51 and LP-52.

  These aqueous dispersions of hydrophobic polymers may be used alone or in combination of two or more as required.

The content of the hydrophobic polymer is preferably 3% by mass or more and 60% by mass or less, and more preferably 5% by mass or more and 50% by mass or less with respect to the entire second non-photosensitive layer coating solution.
The coating amount of the hydrophobic polymer in the second non-photosensitive layer is preferably 0.1 g / m ² or more and 10 g / m ² or less, more preferably 0.2 g / m ² or more and 5 g / m ² or less. Most preferably, it is 0.5 g / m ² or more and 3 g / m ² or less.

  In the second non-photosensitive layer in the present invention, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose or the like may be added as necessary.

In order to control the minimum film forming temperature of the aqueous dispersion of the hydrophobic polymer, a film forming aid may be added. As the film-forming aid, those described in the outermost layer can be used as appropriate.
Moreover, it is preferable to add a thickener to the coating liquid for forming a 2nd non-photosensitive layer. When a thickener is added, a hydrophobic layer having a uniform thickness can be formed. As a thickener, what was demonstrated in the outermost layer can be used suitably.
Further, the viscosity of the second non-photosensitive layer coating liquid to which the thickener is added is preferably 1 mPa · s or more and 200 mPa · s or less, preferably 10 mPa · s or more and 100 mPa · s or less, at 40 ° C. Is more preferably 15 mPa · s or more and 60 mPa · s or less.

  In addition to the binder, various additives can be added to the second non-photosensitive layer. For example, surfactants, pH adjusters, preservatives, antifungal agents and the like can be mentioned as additives.

(3) Image forming layer

(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 105 ° 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 non-photosensitive organic silver salt in the present invention preferably has a silver behenate content of 50 mol% or more and 100 mol% or less. More preferably, the silver behenate content is 85 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less. When the silver behenate content is less than 100 mol%, the remaining organic silver salt is not particularly limited, but a fatty acid silver salt is preferred, and preferred examples include silver lignocerate, silver behenate, silver arachidate, stearin. Examples thereof include silver oxide, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, silver erucate, and mixtures thereof.
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.

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-like, rectangular parallelepiped, cubic or potato-like amorphous 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 as 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.

  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 Although the method for preparing the organic silver salt of the present invention is already well known, it is preferably prepared through the following steps.
a. Formation of organic silver salt by reaction of organic acid or alkali metal salt thereof with water-soluble silver salt b. Remove by-product salts by filtration c. Drying d. Dispersion (dispersion of organic silver salt into desired fine particles using water as a dispersion medium)
The drying process of c is not essential, and the process can proceed to the dispersion process of d in a wet cake state containing moisture to some extent.

(Dispersant)
The organic silver salt can be dispersed using an unreacted organic acid salt as a dispersant, without adding any other dispersant, but preferably various hydrophilic polymers (polyvinyl alcohols, cellulose derivatives). And gelatins) and oligomer dispersants (oligomers derived from phthalic acid, acrylic acid, maleic acid, itaconic acid, etc.), inorganic salts (sodium carbonate, sodium bicarbonate, sodium sulfate, etc.), or surfactants (e.g. It is preferable to disperse using a new dispersing agent such as a nonionic surfactant, an anionic surfactant, an amphoteric surfactant, or a cationic surfactant as an auxiliary agent.
Preferred dispersants are hydrophilic polymer or oligomer dispersants. Examples thereof include polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide acid, polysaccharides, casein, and gelatin. Polyvinyl alcohol is particularly preferable.

(Distribution method)
As a method for producing a solid dispersion of an organic silver salt, various dispersion methods conventionally known in industry can be applied. Examples of a preferable disperser include 1) a bead mill capable of obtaining a dispersion by a mechanical dispersion method using a medium, and 2) a high-pressure homogenizer.
Conventionally, as a generally known method of media dispersion, an organic silver salt powder or a wet cake moistened with water or an organic solvent is made into an aqueous slurry, and the presence of the dispersion media using a known pulverizer is used. A method of pulverizing and dispersing by mechanical force is mentioned below. Examples of the pulverizer used for media dispersion include a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, and a roller mill. Examples of the dispersion medium include steel balls, ceramic balls, glass beads, alumina beads, zirconia silicate beads, zirconia beads, and Ottawa Sand. The average diameter of the dispersion media (beads) is preferably 0.1 mm to 5 mm, more preferably 0.3 mm to 3 mm, even more preferably 0.3 mm to 1 mm, and most preferably 0.3 mm or 0.5 mm. .

In the present invention, it is preferable to use a high-pressure homogenizer for dispersion preparation of organic acid silver. A high-pressure homogenizer is equipped with a high-pressure pulverization unit in the middle of the dispersion flow path, narrows a part of the high-pressure and high-speed dispersion device or the dispersion liquid flow path, and disperses and emulsifies the dispersion liquid at high pressure and high speed. And a device for crushing.
For example, Nanomizer LA (manufactured by Nanomizer Co., Ltd.) in which the dispersions collide with each other in the dispersion channel, Microfluidizer (manufactured by Microfluidax) or Gorin homogenizer with a high-pressure pulverization unit in the dispersion channel ( APS (manufactured by APV), and Genus PY (manufactured by Genus) having a thin tubular channel called an orifice in the channel of the dispersion can be used.

The high-pressure pulverization section provided in the high-pressure homogenizer used in the present invention is a region 1 and 2 shown in FIG. 1 and a region where the flow path of the raw material liquid passing through the dispersing device is bent at a substantially right angle. There is obtained an organic silver salt dispersion in which an organic silver salt is pulverized and dispersed when a high-speed flow of the raw material liquid passes through the high-pressure pulverizing section.
In the present invention, the term “substantially perpendicular” means that the angle of the corner formed from each flow path is 70 degrees to 110 degrees when the flow paths of the raw material liquids are directed to flow paths having different directions.

As the thin tubular flow path (orifice) provided in the high-pressure homogenizer used in the present invention, a flow path diameter of 0.1 mmφ or more is preferably used during preliminary dispersion in order to suppress clogging of the dispersion in the dispersion flow path. More preferably, a flow path diameter of 0.2 mmφ or more is used. Further, the pressure applied to the dispersion is preferably 5 kgf / cm ² or more, more preferably 10 kgf / cm ² or more during preliminary dispersion. Furthermore, at the time of this dispersion, a channel diameter of 0.5 mmφ or less is preferably used, and more preferably, a channel diameter of 0.2 mmφ or less is used. Moreover, as a pressure applied to a dispersion liquid, 100 kgf / cm < ² > or more is preferable, More preferably, it is 280 kgf / cm < ² > or more.

  In the present invention, at least one preliminary dispersion of a raw material liquid comprising an organic silver salt, a solvent and a dispersing agent is performed, and then the main dispersion is performed. In the preliminary dispersion, the dispersion used at the time of the main dispersion is used. By dispersing using a channel diameter larger than the channel diameter, an organic silver salt dispersion having good dispersibility without causing blockage of the channel due to clogging of the dispersion in the dispersion channel at the time of main dispersion is obtained. Can be obtained.

  Specifically, the preliminary dispersion and the main dispersion performed in the production method of the present invention are performed by an apparatus as shown in FIG. 2 or FIG.

  In the apparatus shown in FIG. 2, the raw material liquid is passed from the supply pot A through the auxiliary pump P1, the check valve B, the high pressure pump P2, and the check valve C, and then to the preliminary dispersion orifice E by the switching valve D. Install and perform preliminary dispersion. After the preliminary dispersion, the obtained preliminary dispersion is returned to the supply pot A, passed through the same path as described above, and then introduced into the main dispersion orifice by the switching valve D to perform the main dispersion.

  In the apparatus shown in FIG. 3, the raw material liquid is introduced from the supply pot A1 through the auxiliary pump P1, the check valve B, the high pressure pump P2, the check valve C, and the switching valve D, and then introduced into the preliminary dispersion orifice. Disperse. The obtained preliminary dispersion liquid is supplied to a supply pot A2 provided separately, and is introduced into the dispersion orifice through the auxiliary pump P3, the check valve B1, the high pressure pump P4, the check valve C1, and the switching valve D1. Disperse.

  In the production method of the present invention, the temperature of the dispersion may be controlled as necessary. Adjustment of the raw material liquid temperature before dispersion may be performed in a tank in which the raw material liquid is placed, or may be performed in the middle from the tank to the dispersing action part of the high-pressure homogenizer. In particular, when the dispersion liquid is cooled below the dew point, cooling in the tank has a problem of dew condensation, and it is preferable to perform it in a closed flow path from the tank to the dispersing action part.

  Furthermore, as means for increasing the pressure applied to the dispersion of the high-pressure homogenizer used in the present invention, a method of closing the outlet of a single flow path with a collision plate, a method of making the middle of the flow path a thin tubular flow path (orifice), etc. It may be used.

  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 reduced. 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.

4) Addition amount Although the organic silver salt in the present invention can be used in a desired amount, the total amount of applied silver including silver halide is preferably 0.1 g / m ² or more and 5.0 g / m ² or less, more preferably. It is 0.3 g / m ² or more and 3.0 g / m ² or less, more preferably 0.5 g / m ² or more and 2.0 g / m ² or less.
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.

(Reducing agent)
The photothermographic material of the present invention preferably contains a heat developer which 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).

General 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 ′ each independently represent a hydrogen atom or a substituent that can be substituted on the benzene ring. 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. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

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 capable of substituting for a benzene ring, and X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group capable of substituting for 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 of the alkyl group are the same as the substituent of R ¹¹ , and are a halogen atom, alkoxy group, alkylthio group, aryloxy group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, 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, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, 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, 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. Particularly preferred as R ¹³ is a hydrogen atom, methyl group, ethyl group, propyl group or 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. The primary or secondary alkyl group having 1 to 8 carbon atoms of R ¹³ is more preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and further preferably a methyl group, an ethyl group, or a propyl group.
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 for 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, developed silver tone, and the like 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 by general formula (R) of this invention below is shown, this invention is not limited to these.

Examples of preferable reducing agents of the present invention other than the above are 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 emulsification 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 emulsifying the dispersion. The method of producing is mentioned.

In addition, 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 create 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 No. 10-62895, JP-A No. 11-15116 and the like, A hydrazine-based compound represented by general formula (D) of JP-A No. 2002-156727 or general formula (1) described in JP-A No. 2002-278017, and described in JP-A No. 2001-264929 A phenolic or naphtholic compound represented by the general formula (2) is 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 development accelerators described above, hydrazine compounds represented by the general formula (D) described in JP-A No. 2002-156727 and those described in JP-A No. 2001-264929 A phenol-based or naphthol-based compound represented by the formula (2) is more preferable.

Particularly preferred development accelerators of the present invention are compounds represented by the following general formulas (A-1) and (A-2).
Formula (A-1)
Q1-NHNH-Q2
(In the formula, Q1 represents an aromatic group or a heterocyclic group bonded to —NHNH-Q2 at a carbon atom, and Q2 represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, or a sulfamoyl group. Represents.)

  In the general formula (A-1), the aromatic group or heterocyclic group represented by Q1 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. A 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 Q2 is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as 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-dodecyl) Oxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl include N- benzylcarbamoyl.

  The acyl group represented by Q2 is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms. For example, formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2- Examples include hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, and 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 Q2 is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxymethyl. Phenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl are mentioned. 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 Q2 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 Q2 may further have the groups mentioned as examples of the substituent of the 5- to 7-membered unsaturated ring represented by Q1 at the substitutable position. In the case of having a substituent, these substituents may be the same or different.

  Next, preferred range for the compound represented by formula (A-1) is to be described. Q1 is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, a pyrimidine ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, or a 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. Q2 is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on the nitrogen atom.

  Formula (A-2)

In 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.

R ₂ is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (for example, a methoxy group, a butoxy group, an n-hexyloxy group, an n-decyloxy group, a cyclohexyloxy group, a benzyloxy group), aryl An oxy 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, and 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 of the present invention will be given. The present invention is not limited to these.

(Description of hydrogen bonding compound)
When the reducing agent in the present invention has an aromatic hydroxyl group (—OH) or an 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).

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, the substituent is a halogen atom, alkyl group, aryl group, alkoxy group, amino group, acyl group, acylamino group, alkylthio group, arylthio group, sulfonamide group, 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 for 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 thereof 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. From the viewpoint of the effect 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. Further, 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, JP-A No. 2002-156727, and JP-A No. 2002-318431 in addition to the above.
The compound of the general formula (D) of 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. The compound of the present invention forms 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) of the present invention, It can be isolated in the crystalline 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) of the present invention are mixed as 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) of 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%, still more preferably relative to the reducing agent. It 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, and is 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 in gelatin or other 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.sub. Tani; Imaging Sci. 29, 165 (1985).

5) Heavy Metal The photosensitive silver halide grain of the invention can contain a metal or a metal complex of Group 8 to Group 14 of the periodic table. More preferably, it can contain a metal or a metal complex of Group 8 to Group 10 of the Periodic Table. As the central metal of the group 8 to group 10 metal or metal complex of the periodic table, iron 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. Examples of the hexacyano metal complex 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 aqueous silver nitrate 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. .

Further, regarding a metal atom (for example, [Fe (CN) ₆ ] ⁴⁻ ), a silver salt emulsion desalting method and a chemical sensitization method which can be contained in the silver halide grains used in the present invention, JP-A-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 No. 11-65021, compounds represented by formula (II) of JP-A No. 10-186572, and formulas (I of JP-A No. 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, page 38 to line 20, page 35 of European Patent Publication No. 0803764A1, JP 2001-272747, JP 2001-290238, JP 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 according to 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 gold compound that is usually used. 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-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 mol to 10 ⁻² mol per mol of silver halide. Is about 10 ⁻⁷ mol to 10 ⁻³ mol.
The addition amount of the gold sensitizer varies depending on various conditions, but as a guideline, 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 of the reduction sensitization method, ascorbic acid and aminoiminomethanesulfinic acid are preferable. In addition, it is preferable to use stannous chloride, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, and the like. 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 preferably carried out by ripening while maintaining the pH of the emulsion at 7 or more or pAg at 8.3 or less, and reduction sensitization 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 1 electron or more. 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 photosensitive material in the present invention is a compound selected from the following types 1 and 2 that can emit one electron or more.
(Type 1)
A compound in which a one-electron oxidant produced by one-electron oxidation can further emit one or more electrons with a subsequent bond cleavage reaction.
(Type 2)
A compound capable of emitting one or more electrons after a one-electron oxidant produced by one-electron oxidation undergoes a subsequent bond formation reaction.

First, the compound of type 1 will be described.
JP-A-9-211769 (specific example: 28-) is a compound that is a type 1 compound, and a one-electron oxidant produced by one-electron oxidation can further emit one electron with a subsequent bond cleavage reaction. Compounds PMT-1 to S-37 described in Table E and Table F on page 32), JP-A-9-211774, JP-A-11-95355 (specific examples: compounds INV1-36), JP-T 2001-500996 (Specific examples: Compounds 1-74, 80-87, 92-122), US Pat. No. 5,747,235, US Pat. No. 5,747,236, European Patent 786692A1 (Specific examples: Compounds INV 1-35), “One-photon two-electron sensitizer” or “deprotonated electron donation” described in patents such as European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051 Compound called sensitive agent "and the like. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

  In addition, as a compound of type 1 that can be emitted by one-electron oxidant produced by one-electron oxidation and further releasing one electron or more with a subsequent bond cleavage reaction, a compound represented by the general formula (1) ( General formula (1) described in JP-A-2003-114487), general formula (2) (synonymous with general formula (2) described in JP-A-2003-114487), general formula (3) General formula (1) described in 2003-114488), general formula (4) (synonymous with general formula (2) described in Japanese Patent Application Laid-Open No. 2003-114488), general formula (5) (Japanese Patent Application Laid-Open No. 2003-114488). 114488 (synonymous with general formula (3)), general formula (6) (synonymous with general formula (1) described in JP-A-2003-75950), and general formula (7) (JP-A-2003-75950). Synonymous with general formula (2) described in , General formula (8) (synonymous with general formula (1) described in Japanese Patent Application No. 2003-25886), or chemical reaction formula (1) (chemical reaction formula (1) described in Japanese Patent Application No. 2003-33446) And the compound represented by the general formula (9) (synonymous with the general formula (3) described in Japanese Patent Application No. 2003-33446). The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the formula, RED ₁ and RED ₂ represent a reducing group. R ₁ is a non-metallic atomic group capable of forming a cyclic structure corresponding to a tetrahydro form of a 5-membered or 6-membered aromatic ring (including an aromatic heterocycle) or an octahydro form together with carbon atom (C) and RED _1. Represent. R ₂ represents a hydrogen atom or a substituent. When there are a plurality of R ₂ in the same molecule, these may be the same or different. L ₁ represents a leaving group. ED represents an electron donating group. Z ₁ represents an atomic group capable of forming a 6-membered ring with a nitrogen atom and two carbon atoms of a benzene ring. X ₁ represents a substituent, and m 1 represents an integer of 0 to 3. Z ₂ represents —CR ₁₁ R ₁₂ —, —NR ₁₃ —, or —O—. R ₁₁ and R ₁₂ each independently represents a hydrogen atom or a substituent. R ₁₃ represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. X ₁ represents an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylamino group, an arylamino group, or a heterocyclic amino group. L ₂ represents a carboxy group or a salt thereof, or a hydrogen atom. X ₂ represents a group which forms a 5-membered heterocycle with C═C. Y ₂ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation.

Next, the type 2 compound will be described.
As a compound that can be emitted by one-electron oxidant generated by one-electron oxidation with a type 2 compound and further with one subsequent bond formation reaction, a compound represented by the general formula (10) is disclosed. The reaction represented by the general formula (1) described in 2003-140287) and the chemical reaction formula (1) (synonymous with the chemical reaction formula (1) described in Japanese Patent Application No. 2003-33446) may occur. And a compound represented by the general formula (11) (synonymous with the general formula (2) described in Japanese Patent Application No. 2003-33446). The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

In the formula, X represents a reducing group that is one-electron oxidized. Y reacts with a one-electron oxidant produced by one-electron oxidation of X to form a new bond, a carbon-carbon double bond site, a carbon-carbon triple bond site, an aromatic group site, or a benzo The reactive group containing the non-aromatic heterocyclic part of a condensed ring is represented. L ₂ represents a linking group for linking X and Y. R ₂ represents a hydrogen atom or a substituent. When there are a plurality of R ₂ in the same molecule, these may be the same or different. X ₂ represents a group which forms a 5-membered heterocycle with C═C. Y ₂ represents a group which forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation.

Of the compounds of types 1 and 2, “a compound having an adsorptive group to silver halide in the molecule” or “a compound having a partial structure of a spectral sensitizing dye in the molecule” is preferable.
Typical examples of the adsorptive group to silver halide are groups described in JP-A No. 2003-156823, page 16, right line 1 to page 17, right line 12. The partial structure of the spectral sensitizing dye is a structure described on page 17, right line 34 to page 18, left line 6 of the same specification.

  More preferably, the compound of type 1 or 2 is “a compound having at least one adsorptive group to silver halide in the molecule”. More preferred is “a compound having two or more adsorptive groups to silver halide in the same molecule”. When two or more adsorptive groups are present in a single molecule, these adsorptive groups may be the same or different.

  The adsorptive group is preferably 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 (> NAg) And a nitrogen-containing heterocyclic group having a —NH— group as a heterocyclic partial structure (for example, a benzotriazole group, a benzimidazole group, an indazole group, etc.). 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.

  It is also particularly preferred that the adsorptive group has two or more mercapto groups as a partial structure in the molecule. Here, the mercapto group (—SH) may be a thione group if it can be tautomerized. Preferred 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, A 5-dimercapto-1,2,4-triazole group may be mentioned.

  A quaternary salt structure of nitrogen or phosphorus is also preferably used as the adsorptive group. Specific examples of the quaternary salt structure of nitrogen include an ammonio group (such as a trialkylammonio group, a dialkylaryl (or heteroaryl) ammonio group, an alkyldiaryl (or heteroaryl) ammonio group) or a quaternized nitrogen atom. A group containing a nitrogen-containing heterocyclic group containing The quaternary salt structure of phosphorus includes a phosphonio group (trialkyl phosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group, etc.) Is mentioned. More preferably, a quaternary salt structure of nitrogen is used, and more preferably a 5-membered or 6-membered nitrogen-containing aromatic heterocyclic group containing a quaternized nitrogen atom is used. Particularly preferably, a pyridinio group, a quinolinio group, or an isoquinolinio group is used. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent.

Examples of the counter anion of the quaternary salt include halogen ion, carboxylate ion, sulfonate ion, sulfate ion, perchlorate ion, carbonate ion, nitrate ion, BF ₄ ⁻ , PF ₆ ⁻ , Ph ₄ B ^{− and the} like. It is done. When a group having a negative charge in the carboxylate group or the like is present in the molecule, an inner salt may be formed together with the group. As a counter anion not present in the molecule, a chlorine ion, a bromo ion or a methanesulfonate ion is particularly preferable.

  A preferred structure of the compound represented by types 1 and 2 having a quaternary salt structure of nitrogen or phosphorus as the adsorptive group is represented by the general formula (X).

Formula _{(X) (P-Q 1} -) i -R (-Q 2 -S) j

In the general formula (X), P and R each independently represent a quaternary salt structure of nitrogen or phosphorus that is not a partial structure of a sensitizing dye. Q ₁ and Q ₂ each independently represent a linking group. Specifically, a single bond, an alkylene group, an arylene group, a heterocyclic group, —O—, —S—, —NR _N —, —C (= O) —, —SO ₂ —, —SO—, —P (═O) — represents a group consisting of a single group or a combination of these groups. Here, _RN represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. S is a residue obtained by removing one atom from a compound represented by type (1) or (2). i and j are integers of 1 or more, and i + j is selected from the range of 2-6. Preferably, i is 1 to 3, and j is 1 to 2, more preferably i is 1 or 2, and j is 1, and particularly preferably i is 1 and j is 1. The compound represented by the general formula (X) preferably has a total carbon number of 10 to 100. More preferably, it is 10-70, More preferably, it is 11-60, Most preferably, it is 12-50.

  The compounds of type 1 and type 2 in the present invention may be used at any time during the preparation of the photosensitive silver halide emulsion and during the process of producing the photothermographic material. 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 type 1 and type 2 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 type 1 and type 2 in the present invention are preferably used in an image forming 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 or intermediate layer together with the image forming layer containing, and diffused during coating. The timing of addition of these compounds is preferably before or after the sensitizing dye, preferably from 1 to 10 ^-9 mol to 5 to 10 ^-1 mol, more preferably from 1 to 10 ^-8 mol, per mol of silver halide. It is contained in a silver halide emulsion layer (image forming layer) at a ratio of -5 ra ^10-2 mol.

10) Adsorbing redox compound having an adsorbing group and a reducing group In the present invention, an adsorbing redox compound having an adsorbing group and a reducing group for silver halide is preferably contained in the molecule. The adsorptive redox compound is preferably a compound represented by the following formula (I).

Formula (I) A- (W) n-B
In formula (I), A represents a group that can be adsorbed to silver halide (hereinafter referred to as an adsorbing group), W represents a divalent linking group, n represents 0 or 1, and B represents a reducing group. Represent.

  In the formula (I), the adsorption group represented by A is a group that directly adsorbs to silver halide, or a group that promotes adsorption to silver halide, and specifically, a mercapto group (or a salt thereof). , A thione group (—C (═S) —), a heterocyclic group, a sulfide group, a disulfide group, a cationic group, or an ethynyl group containing at least one atom selected from a nitrogen atom, a sulfur atom, a selenium atom, and a tellurium atom Etc.

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 at least a 5- 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, benzothiazole 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, And triazine ring group. Moreover, the heterocyclic group containing the quaternized nitrogen atom may be sufficient, and in this case, the substituted mercapto group may dissociate and it may become a meso ion. 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, 4 Examples include a heterocyclic group containing a classified nitrogen atom, and a phosphonium ion.
Further, the mercapto group as the adsorptive group may be tautomerized into a thione group.

The thione group as an adsorbing group also includes a chain or cyclic thioamide group, thioureido group, thiourethane group, or dithiocarbamate group.
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 -NH- group capable of forming imino silver (> NAg) as a partial structure of the heterocyclic ring. A nitrogen-containing heterocyclic group, or a heterocyclic group having a -S- group, a -Se- group, a -Te- group, or a = N- group as a partial structure of the heterocyclic ring, which can be coordinated to a silver ion by a coordination bond Examples of the former include benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group, and purine group, and examples of the latter include thiophene group, thiazole group, oxazole group, Thiophene group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, triazine group, seleno Tetrazole group, benzoselenazole group, tellurium azole group, such as benzo tellurium azole group.
Examples of the sulfide group or disulfide group as the adsorptive group include all groups having a partial structure of -S- or -SS-.
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. 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.
An ethynyl group as an adsorptive group means a —C≡CH group, and the hydrogen atom may be substituted.
The adsorbing group may have an arbitrary substituent.

  Further, specific examples of the adsorbing group include those described in the specifications p4 to p7 of JP-A No. 11-95355.

  In the formula (I), preferred as the adsorptive group represented by A is a mercapto-substituted heterocyclic group (for example, 2-mercaptothiadiazole group, 2-mercapto-5-aminothiadiazole group, 3-mercapto-1,2,4). -Triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4-oxadiazole group, 2-mercaptobenzimidazole group, 1,5-dimethyl-1,2,4-triazolium-3-thiolate group 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3,5-dimercapto-1,2,4-triazole group, 2,5-dimercapto-1,3-thiazole group), or Nitrogen-containing heterocyclic group having —NH— group capable of forming imino silver (> NAg) as a partial structure of heterocyclic ring (for example, benzotriazo Group, benzimidazole group, an indazole group), more preferable as an adsorptive group is a 2-mercaptobenzimidazole group, a 3,5-dimercapto-1,2,4-triazole group.

In formula (I), W represents a divalent linking group. Any linking group may be used as long as it does not adversely affect photographic properties. For example, a divalent linking group composed of a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, or a sulfur atom can be used. Specifically, an alkylene group having 1 to 20 carbon atoms (for example, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, etc.), an alkenylene group having 2 to 20 carbon atoms, and an alkynylene group having 2 to 20 carbon atoms. , An arylene group having 6 to 20 carbon atoms (eg, phenylene group, naphthylene group, etc.), —CO—, —SO ₂ —, —O—, —S—, —NR ₁ —, combinations of these linking groups, and the like. It is done. Here, R ₁ represents a hydrogen atom, an alkyl group, a heterocyclic group, or an aryl group.
The linking group represented by W may have an arbitrary substituent.

  In formula (I), the reducing group represented by B represents a group capable of reducing silver ions. For example, a triple bond group such as formyl group, amino group, acetylene group or propargyl group, mercapto group, hydroxylamines. Hydroxamic acids, hydroxyureas, hydroxyurethanes, hydroxysemicarbazides, reductones (including reductone derivatives), anilines, phenols (chroman-6-ols, 2,3-dihydrobenzofuran-5-ols, (Including aminophenols, sulfonamidophenols, and hydroquinones, catechols, resorcinols, polyphenols such as benzenetriols, bisphenols), acylhydrazines, carbamoylhydrazines, 3-pyrazolidones, etc. Residue with one removed And the like. Of course, these may have an arbitrary substituent.

In the formula (I), the reducing group represented by B shows its oxidation potential by Akira Fujishima “Electrochemical measurement method” (pages 150-208, published by Gihodo) or “The Experimental Chemistry Course” edited by the Chemical Society of Japan, 4th edition ( 9 pages 282-344, Maruzen). For example, by rotating disk voltammetry, specifically, a sample is dissolved in a solution of methanol: pH 6.5, Briton-Robinson buffer (Britton-Robinson buffer) = 10%: 90% (volume%), and nitrogen is added for 10 minutes. After aeration of gas, a rotating disc electrode (RDE) made of glassy carbon is used as a working electrode, a platinum wire is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, 25 ° C., 1000 rev / min, 20 mV / sec. It can be measured at the sweep speed. A half-wave potential (E1 / 2) can be obtained from the obtained voltammogram.
In the present invention, the reducing group represented by B preferably has an oxidation potential in the range of about -0.3 V to about 1.0 V when measured by the above measurement method. More preferably, it is in the range of about -0.1V to about 0.8V, and particularly preferably in the range of about 0 to about 0.7V.

  In the formula (I), the reducing group represented by B is preferably selected from hydroxylamines, hydroxamic acids, hydroxyureas, hydroxysemicarbazides, reductones, phenols, acylhydrazines, carbamoylhydrazines, and 3-pyrazolidones. A residue obtained by removing one hydrogen atom.

  The compound of the formula (I) in the present invention may be one in which a ballast group or polymer chain commonly used in an immobile photographic additive such as a coupler is incorporated. Examples of the polymer include those described in JP-A-1-100530.

  The compound of the formula (I) in the present invention may be a bis form or a tris form. The molecular weight of the compound of formula (I) in the present invention is preferably between 100 and 10000, more preferably between 120 and 1000, particularly preferably between 150 and 500.

  Examples of the compound of formula (I) in the present invention are shown below, but the present invention is not limited thereto.

  Furthermore, specific compounds 1 to 30 and 1 ″ -1 to 1 ″ -77 described in European Patent No. 1308776A2 p73 to p87 are also preferable examples of the compound having an adsorbing group and a reducing group in the present invention.

  These compounds can be easily synthesized according to known methods. As the compound of the formula (I) in the present invention, one kind of compound may be used alone, but it is also preferred to use two or more kinds of compounds at the same time. When two or more kinds of compounds are used, they may be added in the same layer or in different layers, and the addition methods may be different.

The compound of formula (I) in the present invention is preferably added to the silver halide emulsion layer, and more preferably added during preparation of the emulsion. When added at the time of emulsion preparation, it can be added at any time during the process. For example, silver halide grain formation process, before the start of desalting process, desalting process, chemical ripening Examples include a step before starting, a chemical ripening step, and a step before preparing a finished emulsion. Moreover, it can also be added in several steps in these processes. Although it is preferably used for the image forming layer, it may be added to the adjacent protective layer or intermediate layer together with the image forming layer and diffused during coating.
The preferred addition amount largely depends on the above-mentioned addition method and the kind of compound to be added, but generally 1 la 10 ⁻⁶ mol to 1 mol, preferably 1 ra 10 ⁻⁵ mol, per 1 mol of photosensitive silver halide. It is 5 ra 10 ⁻¹ mol or less, more preferably 1 ra 10 ⁻⁴ mol or more and 1 ra 10 ⁻¹ mol or less.

  The compound of the formula (I) in the present invention can be added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. At this time, the pH may be appropriately adjusted with an acid or a base, and a surfactant may be allowed to coexist. Furthermore, it can also be dissolved in a high boiling point organic solvent and added as an emulsified dispersion. It can also be added as a solid dispersion.

11) Sensitizing dye The sensitizing dye that can be applied to the present invention can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and is suitable for spectral characteristics of the exposure light source. Sensitizing dyes with sensitivity can be advantageously selected. In particular, the photothermographic material in the invention is preferably spectrally sensitized so as to have a spectral sensitivity peak at 600 nm to 900 nm or 300 nm to 500 nm. Regarding the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A No. 11-65021, compounds represented by formula (II) of JP-A No. 10-186572, and formulas (I of JP-A No. 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, page 38 to line 20, page 35 of European Patent Publication No. 0803764A1, JP 2001-272747, JP 2001-290238, JP 2002-23306, etc. It is described in. These sensitizing dyes may be used alone or in combination of two or more.

The addition amount of the sensitizing dye in the present invention can be set to a desired amount according to 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 mol 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.

12) Combined use of silver halide The photosensitive silver halide emulsion in the photothermographic material used in the invention may be only one kind, or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions). , Different crystal habits, different chemical sensitization conditions). 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.

13) Mixing of silver halide and organic silver salt It is particularly preferred that the photosensitive silver halide grains in the present invention are formed in the absence of non-photosensitive organic silver salt and chemically sensitized. This is because sufficient sensitivity may not be achieved by the method of forming silver halide by adding a halogenating agent to the organic silver salt.
As a method of mixing silver halide and organic silver salt, a method of mixing separately prepared photosensitive silver halide and organic silver salt with a high speed stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer, etc. Alternatively, there may be mentioned a method of preparing an organic silver salt by mixing photosensitive silver halide which has been prepared at any timing during the preparation of the organic silver salt. Any method can preferably obtain the effects of the present invention.

14) 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 organic silver salt-containing layer of the present invention, and suitable binders are transparent or translucent and generally colorless, natural resins and polymers and copolymers, synthetic resins and polymers and copolymers, etc. Film forming media such as gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) ), Poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers , Poly (vinyl acetal) s (eg, poly (vinyl Lumar) 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 (Tg) of the binder of the image forming layer is preferably from −10 ° C. to 70 ° C., more preferably from 5 ° C. to 35 ° C.

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. 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 added to 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 “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 water 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 moisture content at 25 ° C. and 60% RH of the binder polymer of 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 a water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or a micelle form. preferable. The average particle size of the dispersed particles is 1 nm to 50000 nm, preferably 5 nm to 1000 nm, more preferably 10 nm to 500 nm, and still more preferably 50 nm 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.

A polymer latex in which 50% by mass or more of the image forming layer binder in the present invention has 10% by mass or more and 70% by mass or less of butadiene as a monomer component is preferable.
More preferably, it is a polymer latex having 1% by mass or more and 20% by mass or less of the monomer component having an acid group.

<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.

Latex of P-1; -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000, Tg 61 ° C.)
Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
P-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
Latex of P-4; -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C.)
Latex of P-5; -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
Latex of P-6; -St (70) -Bu (27) -IA (3)-(crosslinkability)
Latex of P-7; -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
P-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
Latex (crosslinkability) of P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-
P-10; latex of VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80000)
P-11; latex of VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
Latex of P-12; -Et (90) -MAA (10)-(molecular weight 12000)
P-13; Latex of -St (70) -2EHA (27) -AA (3) (molecular weight 130000, Tg 43 ° C)
P-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33,000, Tg 47 ° C.)
Latex of P-15; -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
Latex of P-16; -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; 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 FINITEX ES650, 611, 675, 850 (above Dainippon Ink and Chemicals), WD-size, WMS (Eastman Chemical). Examples of rubbers such as HYDRAN AP10, 20, 30, 40 (above made by Dainippon Ink Chemical Co., Ltd.) include LACSTAR 7310K, 3307B, 4700H, 7132C (made by Dainippon Ink Chemical Co., Ltd.) , Nipol Lx416, 410, 438C, 2507 (all manufactured 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 of 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 of 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 aforementioned P-3 to P-8,15, commercially available 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) of the present invention is preferably formed using a polymer latex. The amount of binder in the organic silver salt-containing layer is such that the mass ratio of total binder / 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 of 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 , and still more preferably 2 g / m ^{2 to} 10 g / m ^2. Range. The image forming layer of the present invention may contain a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like.
<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 which 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 of 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 of the general formula (H) of the present invention are shown below.

Other preferred polyhalogen compounds of the present invention include compounds described in JP-A Nos. 2001-31644, 2001-56526, and 2001-209145.
The compound represented by formula (H) of the present invention is preferably used in the range of 10 ⁻⁴ mol to 1 mol, more preferably 10 ⁻³ mol, per mol of the non-photosensitive silver salt of the image forming layer. It is preferable to use in the range of ˜0.5 mol, more preferably in the range of 1 × 10 ⁻² mol to 0.2 mol.
In the present invention, the antifoggant is added to the light-sensitive material by the method 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 preferably 1 × 10 ⁻⁶ mol to 2 mol, and more preferably 1 × 10 ⁻³ mol to 0.5 mol, per mol of silver.

(Other additives)
1) Mercapto, disulfide, and thiones In the present invention, mercapto compounds and disulfide compounds are used to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, and to improve 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-2002-303955, JP-A-2002-303951, and the like are preferable.

2) Toning Agent In the photothermographic material of the present invention, it is preferable to add a toning agent. For the toning agent, paragraph Nos. 0054 to 0055 of JP-A No. 10-62899, page 21 to No. 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) Phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6-t-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxy Phthalazine and 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferred, and a combination of phthalazines and phthalic acids is particularly preferred. Of these, a particularly preferred combination is a combination of 6-isopropylphthalazine and phthalic acid or 4-methylphthalic acid.

3) Plasticizers and lubricants Plasticizers and lubricants that can be used in the photosensitive layer of the present 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 and Pigment The photosensitive layer of the present invention has various dyes and pigments (for example, CI Pigment Blue 60, CI Pigment, etc.) from the viewpoints of color tone improvement, prevention of interference fringes during laser exposure, and prevention of irradiation. 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) Nucleator The photothermographic material used in the invention preferably has a nucleator added to the image forming layer. Regarding the nucleating agent and the method and amount of addition thereof, JP-A No. 11-65021, paragraph No. 0118, JP-A No. 11-223898, paragraph Nos. 0136 to 0193, JP-A No. 2000-284399, the formula (H) , 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: The nucleation accelerators are 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 at 5 mmol or less, more preferably 1 mmol or less, per mol of silver on the side having the image forming layer containing photosensitive silver halide.
When a nucleating 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, ammonium hexametaphosphate and the like.
The amount of the acid or salt thereof formed by hydration of diphosphorus pentoxide (the coating amount per 1 m ^{2 of the} light-sensitive material) may be a desired amount according to the performance such as sensitivity and fog, but is 0.1 mg / m ^2. preferably ^{~500mg / m 2, 0.5mg / m} 2 ~100mg / m 2 is more preferable.

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution of 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.

(Layer structure and components)
The image forming layer of the present 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, an organic silver salt and a light-sensitive silver halide are contained in the first image forming layer (usually a layer adjacent to the support), and some in the second image forming layer or both layers. 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 multi-dye multicolor photosensitive photothermographic materials, each emulsion layer is generally functional or non-functional between each photosensitive layer as described in US Pat. No. 4,460,681. By using different barrier layers, they are distinguished from each other and held.
The photothermographic material of the present invention can have a non-photosensitive layer in addition to the image forming layer. The non-photosensitive layer includes (a) a surface protective layer provided on the image forming layer (on the side farther than the support), (b) between the plurality of image forming layers and between the image forming layer and the protective layer. It can be classified into an intermediate layer provided therebetween, (c) an undercoat layer provided between the image forming layer and the support, and (d) a back layer provided on the opposite side of the image forming layer.

  In addition, although a layer acting as an optical filter can be provided, it is provided as the layer (a) or (b). The antihalation layer is provided on the photosensitive material as the layer (c) or (d).

1) 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 of the present invention, gelatin is preferable, but it is also preferable to use polyvinyl alcohol (PVA) or a combination thereof. 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 0.3g ^{/ m 2} ~4.0g ^/ m 2 as a polyvinyl alcohol coating amount (per support 1 m ²⁾ of the protective layer (per one ^{layer), 0.3g / m 2 ~2.0g /} m 2 Is more preferable.

All (including water-soluble polymer and latex polymer) binder preferably 0.3g ^{/ m 2} ~5.0g ^/ m 2 as a coating amount (per support 1 m ²⁾ of the surface protective layer (per one layer), 0. 3g ^{/ m 2} ~2.0g ^/ m 2 is more preferable.

2) Antihalation layer In the photothermographic material of the invention, the antihalation layer can be provided on the side farther from the light source than the photosensitive 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. When 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 decolorable 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 the dye for obtaining such an optical density is generally 0.001g ^{/ m 2} ~1g ^/ m 2 approximately.

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 photothermographic material or photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.
In thermal decoloration using such decoloring dye and base precursor, substances that lower the melting point by 3 ° C. or more when mixed with a base precursor as described in JP-A-11-352626 (for example, diphenylsulfone, 4-chlorophenyl, etc.) (Phenyl) sulfone), 2-naphthylbenzoate, and the like are preferably used in view of thermal decoloring properties.

3) Back Layer Back layers that can be applied to the present invention are 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 back layer provided on the opposite side of the photosensitive layer is preferable as the layer to be added.
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 dyes for this purpose, azomethine oil-soluble dyes described in JP-A-4-359967 and JP-A-4-359968, which have low absorption intensity on the short wavelength side, and phthalocyanine-based water-soluble dyes described in JP-A-2003-295388 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.

  The photothermographic material in the invention is a so-called single-sided photosensitive material having a photosensitive layer containing at least one silver halide emulsion on one side of a support and a back layer on the other side. preferable.

4) Matting Agent In the present invention, it is preferable to add a matting agent for improving transportability, and 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 μm 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 emulsion surface may have any matte degree as long as no stardust failure occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, and 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.

5) Polymer Latex When the photothermographic material of the present invention is used for printing applications in which dimensional change is a problem, it is preferable to use a polymer latex for the surface protective layer or the back layer. For such polymer latex, “Synthetic resin emulsion (Hiraku Okuda, Hiroshi Inagaki, published by Kobunshi Publishing (1978))”, “Application of synthetic latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, Takashi "Molecular Publications (1993))" and "Synthetic Latex Chemistry (Muroichi Muroi, published by High Polymers Publication (1970))", specifically, methyl methacrylate (33.5% by mass) / Ethyl acrylate (50 wt%) / methacrylic acid (16.5 wt%) copolymer latex, methyl methacrylate (47.5 wt%) / butadiene (47.5 wt%) / itaconic acid (5 wt%) copolymer Latex, latex of ethyl acrylate / methacrylic acid copolymer, methyl methacrylate (58.9% by mass) / 2-ethyl Latex of xyl acrylate (25.4 mass%) / styrene (8.6 mass%) / 2-hydroxyethyl methacrylate (5.1 mass%) / acrylic acid (2.0 mass%) copolymer, methyl methacrylate (64. 0 mass%) / styrene (9.0 mass%) / butyl acrylate (20.0 mass%) / 2-hydroxyethyl methacrylate (5.0 mass%) / acrylic acid (2.0 mass%) copolymer latex, etc. Is mentioned. Furthermore, as a binder for the surface protective layer, a combination of polymer latex described in Japanese Patent Application No. 11-6872 and a technique described in Paragraph Nos. 0021 to 0025 of Japanese Patent Application Laid-Open No. 2000-267226, Japanese Patent Application No. 11-6872 The technology described in paragraph numbers 0027 to 0028 of the specification and the technology described in paragraph numbers 0023 to 0041 of JP 2000-19678 may be applied. The ratio of the polymer latex in the surface protective layer is preferably 10% by mass or more and 90% by mass or less, and particularly preferably 20% by mass or more and 80% by mass or less of the total binder.

6) Membrane pH
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. For the adjustment of the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, and 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. In addition, the measuring method of film surface pH is described in paragraph number 0123 of Unexamined-Japanese-Patent No. 2000-284399.

7) Hardener A hardener may be used for each layer such as the photosensitive layer, protective layer, and back layer of 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 thereof, 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.

8) Surfactant As for the surfactant applicable to the present invention, paragraph No. 0132 of JP-A No. 11-65021, paragraph No. 0133 of the solvent, paragraph No. 0134 of the support, antistatic or conductive layer Paragraph No. 0135 for the method of obtaining a color image, paragraph No. 0136 for JP-A No. 11-84573 and paragraph Nos. 0049 to 0062 of Japanese Patent Application No. 11-106881 for the slip agent. Has been.
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, JP-A No. 2003-57780, and Japanese Patent Application No. 2001-264110. In particular, the fluorosurfactants described in JP-A No. 2003-57780 and Japanese Patent Application No. 2001-264110 are preferable in terms of charge adjustment capability, stability of the coated surface, and smoothness when coating and production is performed with an aqueous coating solution. The fluorine-containing 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 0.01 to 10 mg / ^{m 2,} the range of 0.1 to 5 mg / ^{m 2} is more preferable.

9) Antistatic agent In this 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 include 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 of 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 of the present invention include 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.

10) Support The transparent support was subjected to a heat treatment 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 heat shrinkage strain generated during heat development processing. Polyester, particularly polyethylene 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, paragraphs 0063-0080. 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.

11) 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.

12) Coating method The photothermographic material in the invention may be coated 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. In the organic silver salt-containing layer coating solution of the present invention, the viscosity at a shear rate of 0.1S- ¹ 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. . Moreover, in shear rate 1000S- ¹ , 1 mPa * s or more and 200 mPa * s or less are preferable, More preferably, they are 5 mPa * s or more and 80 mPa * s or less.

In the case of preparing the coating liquid of the present invention, a known in-line mixer or implant mixer is preferably used when mixing two kinds of liquids. A preferred in-line mixer of 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. A preferable defoaming treatment method of the present invention is the method described in JP-A No. 2002-66431.
When applying the coating solution of 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. The preferred drying method of the present invention is described in detail in JP-A Nos. 2001-194749 and 2002-139814.
The photothermographic material of the present invention is preferably subjected to a heat treatment immediately after coating and drying in order to improve 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 film surface temperature of 70 to 90 ° C. and a heating time of 2 to 10 seconds. A preferable heat treatment method of 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).

13) Packaging material The photosensitive material of the present invention is packaged with a packaging material having a low oxygen permeability and / or moisture permeability in order to suppress fluctuations in photographic performance during raw storage or to improve curling, curling, etc. It is preferable. 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.
Specific examples of the packaging material having a low oxygen permeability and / or moisture permeability are disclosed in, for example, JP-A-8-254793. This is a packaging material described in JP-A-2000-206653.
14) Other available technologies

  Techniques that can be used for the photothermographic material of the present invention include EP80364A1, EP883022A1, WO98 / 36322, JP56-62648, 58-62644, JP9-43766, and 9-. 281637, 9-297367, 9-304869, 9-311405, 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 10-197987, 10- 07001, 10-207004, 10-221807, 10-282601, 10-288823, 10-288824, 10-307365, 10-312038, 10-339934 11-7100, 11-15105, 11-24200, 11-24201, 11-30201, 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, 11-30538 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, JP 2000-187298, 2000-10229 2000-47345, 2000-206642, 2000-98530, 2000-98531, 2000-112059, 2000-112060, 2000-112104, 2000-112604, No. 2000-171936 is also mentioned.

(Image forming method)
The photothermographic material of the present invention may be a “single-sided type” having an image forming layer only on one side of a support, or a double-sided type having image forming layers on both sides.
<Double-sided photothermographic material>
The photothermographic material of the present invention can be preferably used in an image forming method for recording an X-ray image using an X-ray intensifying screen.
The process of forming an image using these photothermographic materials comprises the following processes.
(A) a step of obtaining an image forming assembly by installing the photothermographic material between a pair of X-ray intensifying screens;
(B) placing a subject between the assembly and the X-ray source;
(C) irradiating the subject with X-rays having an energy level in the range of 25 kVp to 125 kVp;
(D) removing the photothermographic material from the assembly;
(E) A step of heating the photothermographic material taken out at a temperature in the range of 90 ° C to 180 ° C.

  The photothermographic material used in the assembly of the present invention is an image obtained by performing stair exposure with X-rays and heat development on an orthogonal coordinate having the same coordinate axis unit length for optical density (D) and exposure amount (log E). In the characteristic curve, the average gamma (γ) formed by the point of minimum density (Dmin) + density 0.25 and the point of minimum density (Dmin) + density 2.0 is preferably 1.8 or more and 4.3. It is more preferably 0.0 or more and 4.0 or less, and still more preferably 3.2 or more and 4.0 or less. Dmax is preferably 3.0 or more, and 3.3 or more is particularly preferable as an image forming material for mammography. In the X-ray imaging system of the present invention, when a photothermographic material having such a characteristic curve is used, an X-ray image having excellent photographic characteristics such that the legs are extremely extended and the gamma is high in the medium density portion. Is obtained. Due to this photographic characteristic, the description of the low density region such as the mediastinum with a small amount of X-ray transmission and heart shadow is good, and the density becomes easy to see even in the image of the lung field with a large amount of X-ray transmission. In addition, there is an advantage that the contrast becomes good.

  The photothermographic material having the preferable characteristic curve as described above can be easily obtained by, for example, a method in which each of the image forming layers on both sides is composed of two or more silver halide emulsion layers having different sensitivities. Can be manufactured. In particular, it is preferable to form an image forming layer using a high-sensitivity emulsion for the upper layer and an emulsion having low sensitivity and high photographic characteristics for the lower layer. When such an image forming layer comprising two layers is used, the difference in sensitivity of the silver halide emulsions between the respective layers is 1.5 to 20 times, preferably 2 to 15 times. The ratio of the amount of emulsion used to form each layer varies depending on the sensitivity difference and covering power of the emulsion used. In general, the larger the sensitivity difference, the lower the usage ratio of the emulsion on the high sensitivity side. For example, when the difference in sensitivity is double, the preferable ratio of each emulsion is 1:20 or more and 1:50 or less as a high-sensitivity emulsion and a low-sensitivity emulsion in terms of silver when the covering power is almost equal. It is adjusted to be a range value.

  The technique of crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material) is described in JP-A-2-68539, page 13, lower left column, line 1 to page 14, lower left column, line 9; Dyes or dyes and mordants can be used.

  Next, the fluorescent intensifying screen (radiation intensifying screen) of the present invention will be described. The radiation intensifying screen includes, as a basic structure, a support and a phosphor layer formed on one side thereof. The phosphor layer is a layer in which a phosphor is dispersed in a binder. In general, a transparent protective film is provided on the surface of the phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is chemically altered or Protects against physical shock.

In the present invention, preferred phosphors include those shown below. Tungstate phosphors (CaWO ₄ , MgWO ₄ , CaWO ₄ : Pb, etc.), terbium activated rare earth oxysulfide phosphors [Y ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, (Y, Gd) O ₂ S: Tb, Tm, etc.], terbium-activated rare earth phosphate phosphors (YPO ₄ : Tb, GdPO ₄ : Tb, LaPO ₄ : Tb, etc.), terbium activated rare earth oxyhalide phosphors (LaOBr: Tb, LaOBr: Tb, Tm, LaOCl: Tb, LaOCl: Tb, Tm, LaOBr: Tb, GdOBr: Tb, GdOCl: Tb, etc.) , thulium activated rare earth oxyhalide phosphor (LaOBr: Tm, LaOCl: Tm, etc.), barium sulfate phosphor [BaSO _4: Pb, Ba ^{_{O 4: Eu 2+, (Ba}} , Sr) SO 4: Eu 2+ , etc.], divalent europium activated alkaline earth metal phosphate phosphor ^{_{[(Ba 2 PO 4) 2:}} Eu 2+, (Ba 2 PO 4 ) ₂ : Eu ²⁺ etc.] Divalent europium activated alkaline earth metal fluoride halide phosphor [BaFCl: Eu ²⁺ , BaFBr: Eu ²⁺ , BaFCl: Eu ²⁺ , Tb, BaFBr: Eu ²⁺ , Tb, BaF ₂ · BaCl · KCl: Eu ²⁺ , (Ba, Mg) F ₂ · BaCl · KCl: Eu ²⁺ etc.], iodide phosphors (CsI: Na, CsI: Tl, NaI, KI: Tl etc.), sulfides Phosphors [ZnS: Ag (Zn, Cd) S: Ag, (Zn, Cd) S: Cu, (Zn, Cd) S: Cu, Al, etc.], hafnium phosphate phosphors (HfP ₂ O ₇ : Cu, etc.), YTaO ₄ and various activators added as the emission center. However, the phosphor used in the present invention is not limited to these, and any phosphor that emits light in the visible or near ultraviolet region when irradiated with radiation can be used.

  The fluorescent intensifying screen used in the present invention is preferably filled with a phosphor with an inclined particle size structure. In particular, it is preferable to apply phosphor particles having a large particle size to the surface protective layer side, and to apply phosphor particles having a small particle size to the support side, and those having a small particle size are 0.5 μm to 2.0 μm. The thing of a particle size has the preferable range of 10 micrometers-30 micrometers.

<Single-sided photothermographic material>
The single-sided photothermographic material of the present invention is particularly preferably used as a mammographic X-ray photosensitive material.
In the single-sided photothermographic material used for this purpose, it is important to design the contrast of the obtained image within an appropriate range.

  With respect to preferable constitutional requirements as an X-ray photosensitive material for mammography, the descriptions in JP-A-5-45807, JP-A-10-62881, JP-A-10-54900, and JP-A-11-109564 can be referred to. .

<Combination with ultraviolet fluorescent screen>
As an image forming method using the photothermographic material of the present invention, a method of forming an image by combining with a phosphor having a main peak preferably at 400 nm or less can be used. More preferably, a method of forming an image in combination with a phosphor having a main peak at 380 nm or less is preferable. Either a double-sided sensitive material or a single-sided sensitive material can be used as an assembly. As the screen having a main emission peak at 400 nm or less, the screens described in JP-A-6-11804 and WO93 / 01521 are used, but not limited thereto. As a technique of ultraviolet crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material), the technique described in JP-A-8-76307 can be used. As the ultraviolet absorbing dye, the dye described in JP-A No. 2001-144030 is particularly preferable.

<Laser exposure>
As an image forming method using the photothermographic material of the present invention, a digital image forming method for outputting digitized image information with a laser beam is also preferable.
As the laser, a red to infrared light emitting He—Ne laser, a red semiconductor laser, a blue to green light emitting Ar ⁺ , He—Ne, He—Cd laser, or a blue semiconductor laser can be used. Preferred is a red to infrared semiconductor laser, and the peak wavelength of the laser light 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 an 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 is oscillated in a vertical multi by a method such as high frequency superposition.

<Heat 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. The preferred development temperature is 80 ° C to 250 ° C, more preferably 100 ° C to 140 ° C.
The development time is preferably 1 to 60 seconds, more preferably 5 to 30 seconds, and particularly preferably 5 to 20 seconds.

  A plate heater method is preferred as the heat development method. The heat development method using the plate heater method is preferably a method described in JP-A-11-133572. The heat development photosensitive material on which a latent image is formed is brought into contact with a heating means in a heat development part, and heat for obtaining a visible image. In the developing device, 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 heat is interposed between the press roller and the plate heater. A thermal development apparatus that performs thermal development by passing a development photosensitive material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature of the tip portion by about 1 ° C. to 10 ° C.

  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 changes in the shape of the support of the photothermographic material due to heating of the photothermographic material.

<System>
As a medical laser imager provided with an exposure part and a heat development part, Fuji Medical Dry Imager-FM-DPL can be mentioned. The system is Fuji Medical Review No. 8, pages 39 to 55, and these techniques can be used. Further, it can also be applied as a photothermographic material for a laser imager in “ADnetwork” proposed by Fuji Medical Co., Ltd. as a network system conforming 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. Particularly preferred is a photothermographic material for medical diagnosis.

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

Example 1
(Preparation of PET support)
1-1. 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.) was obtained. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to prepare an unstretched film.

This was longitudinally stretched 3.3 times 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.

1-2. 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 <Preparation of undercoat layer coating solution>
Formula (1) (for photosensitive layer side undercoat layer)
46.8 g of pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Bailonal MD-1200 10.4g manufactured by Toyobo Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 1% by mass solution 11.0 g
MP-1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
931 ml of distilled water

Formula (2) (for back layer 1st layer)
Styrene-butadiene copolymer latex 130.8 g
(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) 5.2 g
10% 1% by weight aqueous solution of sodium laurylbenzenesulfonate
Polystyrene particle dispersion (average particle size 2 μm, 20 mass%) 0.5 g
854 ml of distilled water

Formula (3) (for back side second layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.5 μm, 17 mass% dispersion)
84g
7.9g gelatin
10g Metros TC-5 (2 mass% aqueous solution) manufactured by Shin-Etsu Chemical Co., Ltd.
10% 1% by weight aqueous solution of sodium dodecylbenzenesulfonate
NaOH (1% by mass) 7g
Proxel (Abyssia) 0.5g
Distilled water 881ml

After both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm are subjected to the corona discharge treatment, the undercoat coating solution formulation (1) is applied on one side (photosensitive layer surface) with a wire bar with a wet coating amount of 6 .6ml / m 2 was applied ^(per one side) and dried for 5 minutes at 180 ° C., then the amount of wet coating the coating solution for the undercoat was coated (2) by a wire bar on the rear surface (back surface) 5. was applied so as to 7 ml / ^{m 2} and dried 5 minutes at 180 ° C., wet coating amount is 8.4 ml / ^{m 2} further backside (the back face) the coating solution for the undercoat was coated (3) with a wire bar It was applied as described above 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)
2.5 kg of the 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 were added to make a total amount of 8 Then, the mixture was dispersed with beads using a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.). 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 subjected to spectral absorption measurement and 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 The container was kept at 40 ° C., and gelatin was dissolved by adding 40 g of gelatin, 35 mg of benzoisothiazolinone and 840 ml of water. Further, 5.8 ml of 1 mol / l aqueous sodium hydroxide solution, 5 g of 10% by weight emulsion of liquid paraffin, 5 g of 10% by weight emulsion of trimethylolpropane triisostearate, di (2-ethylhexyl) sodium sulfosuccinate 5 10 ml of a mass% aqueous solution, 20 ml of a 3 mass% aqueous solution of sodium polystyrenesulfonate, 2.4 ml of a 2 mass% solution of a fluorosurfactant (F-1), and 2 of a 2 mass% solution of a fluorosurfactant (F-2) .4 ml of a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization weight ratio 57/8/28/5/2) latex 19% by weight 32 g 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.

4) Application of Back Layer On the back surface side of the undercoat support, the coating amount of the antihalation layer coating solution is 0.52 g / m ² and the coating amount of the back surface protective layer coating solution is 1 A simultaneous multi-layer coating was applied so as to be 7 g / m ² , followed by drying to form a 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 >>
A solution prepared by adding 3.1 ml of 1% by mass potassium bromide solution to 1421 ml of distilled water and further adding 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 92.2 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. Solution B diluted in a total amount 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 Solution C and Solution D so as to be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after 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 mol of silver, and further 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 the total of the sensitizing dyes A and B per mol of silver, and N was added after 1 minute. , N′-dihydroxy-N ″, N ″ -diethylmelamine in 1.3 ml of a 0.8 mass% methanol solution was added, and further 4 minutes later, 5-methyl-2-mercaptobenzimidazole was added to the silver 4.8 × 10 ⁻³ mole per mole, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in a methanol solution with 5.4 × 10 ⁻³ mole 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 prepared silver halide emulsion were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.042 μm and a sphere equivalent diameter variation coefficient of 20%. 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 mol, the amount of tellurium sensitizer C changed to 1 mole of silver per 5.2 × 10 ^-4 mol, silver bromide aurate after addition thirds of tellurium sensitizer C mole per 5 × 10 ^{- A} silver halide emulsion 3 was obtained in the same manner as Emulsion 1 except that ⁴ mol and 2 × 10 ⁻³ mol of 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, as "a compound in which a one-electron oxidant produced by one-electron oxidation can emit one electron or more", each of compounds 1, 20 and 26 is 2 × 10 ⁻³ per mole of silver halide. Molar amounts were added.
Further, water was added so that the content of silver halide per 1 kg of the mixed emulsion for coating solution was 38.2 g as silver. 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added so as to be 0.34 g per kg of the mixed emulsion for coating solution.

2) Preparation of fatty acid silver dispersion <Preparation of fatty acid silver dispersion A>
Recrystallized behenic acid (behenic acid content 99 mol%) 88 kg, distilled water 422 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, reacted. Sodium behenate solution A was obtained. 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 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 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 addition of the aqueous silver nitrate solution is completed, 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 aqueous silver nitrate solution were arranged symmetrically 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.

  Add 19.3 kg of polyvinyl alcohol (trade name: PVA-217) as a dispersant to the wet cake equivalent to 260 kg of dry solids, add water to bring the total amount to 1000 kg, and then slurry with a dissolver blade. Pre-dispersed with a mixer (manufactured by Mizuho Kogyo Co., Ltd .: PM-10 type).

Next, the pre-dispersed undiluted 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.

  The morphology of the obtained silver behenate particles was evaluated by electron microscope photography. The shape was approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped were designated as a, b, and c from the shortest side. The average value of the 100 particles obtained was a crystal having a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, an average aspect ratio of 2.1, and a sphere equivalent diameter variation coefficient of 11%. . (A, b, and c are defined in the text.)

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 Liquid-1 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 and the internal temperature was raised 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 the mixture was stirred for 3 hours. After the completion of the reaction, the internal temperature was lowered to room temperature, and then 25% aqueous ammonia was added to adjust the pH to 8.35. 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 to obtain 774.7 g of SBR latex. 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.).
12) Preparation of SBR latex liquid-2 The addition amount of 25% aqueous ammonia used in the preparation of SBR latex liquid-1 was adjusted to pH 7.5.
13) Preparation of SBR Latex Solution-3 Adjust the amount of 25% aqueous ammonia used in the preparation of SBR Latex Solution-1, and adjust the pH.
Prepared to 7.0.
14) Preparation of SBR Latex Liquid-4 Adjust the amount of 25% aqueous ammonia used in the preparation of SBR Latex Liquid-1, and adjust the pH.
Prepared to 6.5.

2. Preparation of coating liquid 1-1) Preparation of image forming layer coating liquid I-1 1000 g of the fatty acid silver dispersion obtained above, 135 ml of water, 36 g of pigment-1 dispersion, 25 g of organic polyhalogen compound-1 dispersion, organic 39 g of polyhalogen compound-2 dispersion, 171 g of phthalazine compound-1 solution, 1060 g of SBR latex (Tg: 17 ° C.) liquid, 75 g of reducing agent-1 dispersion, 75 g of reducing agent-2 dispersion, hydrogen bonding compound-1 dispersion 55 g, development accelerator-1 dispersion 4.8 g, development accelerator-2 dispersion 5.2 g, color tone modifier-1 dispersion 2.1 g, mercapto compound-1 aqueous solution 9 ml, mercapto compound-2 aqueous solution 27 ml. After the sequential addition, the viscosity of the liquid at this point was 25 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm).
Immediately before coating, 140 g of silver halide mixed emulsion A was added and mixed well, and the image forming layer coating solution was fed directly to the coating die.
1-2) Preparation of Image Forming Layer Coating Liquid I-2 1000 g of the fatty acid silver dispersion obtained above, 135 ml of water, 36 g of pigment-1 dispersion, 25 g of organic polyhalogen compound-1 dispersion, organic polyhalogen compound- 2 dispersion 39g, phthalazine compound-1 solution 171g, SBR latex (described in Table 2) 1060g, reducing agent-1 dispersion 75g, reducing agent-2 dispersion 75g, hydrogen bonding compound-1 dispersion 55g, development acceleration Agent-1 dispersion 4.8 g, development accelerator-2 dispersion 5.2 g, color tone modifier-1 dispersion 2.1 g, mercapto compound-1 aqueous solution 9 ml, mercapto compound-2 aqueous solution 27 ml were sequentially added, The acids listed in Tables 1 to 3 were added as acids for lowering the pH, and the pHs shown in Tables 1 to 3 were adjusted. Further, the water was adjusted so that the viscosity liquid at this time was the same as the image forming layer coating liquid I-1.
Immediately before coating, 140 g of silver halide mixed emulsion A was added and mixed well, and the image forming layer coating solution was fed directly to the coating die.

2) Preparation of coating solution for second intermediate layer 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 18.5% by weight aqueous solution, 27 ml of 5% by weight aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 57 / 8/28/5/2) 27% of 5% aqueous solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.) in 4200 ml of 19% by weight latex, 135 ml of 20% by weight aqueous solution of diammonium phthalate, total amount 10000g Add water so that the pH is 7.5. An intermediate layer coating solution was prepared by adjusting with aOH, and the 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). The coating solution pH was 6.5.

3) Preparation of first intermediate layer coating solution (latex binder layer)

<< Preparation of First Intermediate Layer Coating Solution-A-1 >>
In the preparation of the second intermediate layer coating solution, polyvinyl alcohol PVA-205 and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer were used in the image forming layer shown in Table 1-2. It changed into the latex SBR-1 used, and prepared the 1st intermediate | middle layer coating liquid-A-1.
The coating solution pH was 8.1.

<< Preparation of First Intermediate Layer Coating Solution-A-2 to 3 >>
Table 1-3 shows polyvinyl alcohol PVA-205 and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer used in the preparation of the first intermediate layer coating solution-A-1. The first intermediate layer coating liquids -A-2 to 3 were prepared by changing to the binder shown in FIG.
The coating solution pH was as shown in Table 1-3.

4) Preparation of coating solution for surface protective layer first layer (first non-photosensitive layer) 100 g of inert gelatin and 10 mg of benzoisothiazolinone were dissolved in 840 ml of water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic. Acid copolymer (copolymerization mass ratio 57/8/28/5/2) 19 mass% latex 180 g, phthalic acid 15 mass% methanol solution 46 ml, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5 mass 5.4 ml of a 5% aqueous solution was added and mixed, and 40 ml of 4% by weight chromium alum was mixed with a static mixer immediately before coating, and the mixture was fed to the coating die so that the amount of the coating solution was 26.1 ml / m ^2. did.
The coating solution pH was 3.9. This was designated as coating liquid N-1.
Before mixing the chrome alum, an aqueous sodium hydroxide solution was added to raise the coating solution pH to 4.1. This was designated as coating liquid N-2.

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, 40 g of 10% by mass of liquid paraffin and 10% by mass of dipentaerythrityl hexaisostearate are mixed. 40 g, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) latex 19% by weight solution 180 g, phthalic acid 15% by weight methanol solution 40 ml, 5.5 ml of a 1% by weight solution of a fluorosurfactant (F-1), 5.5 ml of a 1% by weight aqueous solution of a fluorosurfactant (F-2), and di (2-ethylhexyl) sodium sulfosuccinate 28 ml of 5% by weight aqueous solution of polymethyl methacrylate fine particles (average A mixture of 4 g of particle size 0.7 μm, volume weighted average distribution 30%) and 21 g of polymethyl methacrylate fine particles (average particle size 3.6 μm, volume weighted average distribution 60%) is used as a surface protective layer coating solution. The solution was fed to the coating die so as to be 3 ml / m ² .
The coating solution pH was 4.0.

3. Preparation of photothermographic material-1 to 14 Image forming layer, first intermediate layer, second intermediate layer, surface protective layer first layer (first non-photosensitive layer) from the undercoat surface to the surface opposite to the back surface, Samples of the photothermographic material were prepared by simultaneous multilayer coating by the slide bead coating method in the order of the surface protective layer second layer. The relationship between sample No. and each coating solution used is shown in Tables 1-3.
The coating amount (g / m ² ) of each compound in the image forming layer is as follows.
The applied silver amount was 1.37 g / m ² .
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-1 0.38
Reducing agent-2 0.38
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-1 0.002
Mercapto compound-2 0.012
Silver halide (as Ag) 0.13

  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 samples were cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows. .
<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 Each sample was exposed with Fuji Medical Co., Ltd. dry laser imager DRYPIX7000 (mounted with a 660 nm semiconductor laser with a maximum output of 50 mW (IIIB)), and thermally developed (107 ° C-121 ° C-121). (Total 14 seconds with 3 panel heaters set at 0 ° C.).

3) Evaluation item Evaluation method of coated surface:
The entire surface of each sample was uniformly exposed so that the density was 1.5, and each film was heat-developed under the same conditions as the evaluation of photographic properties, and evaluated by the number of coating stripes per unit coating width. A photothermographic material excellent in coating property is one having fewer coating stripes.
The evaluation criteria are as follows.
A: No streak is observed.
○: Slightly thin streaks occur.
Δ: Slightly dark streaks are generated.
X: Application streaks occur on the entire surface.
How to evaluate haze:
The haze of the obtained sample is turbidimeter (cloudiness meter) (NH2000: manufactured by Nippon Denshoku Industries Co., Ltd.) according to “How to determine haze of plastic-transparent material” (JIS K 7136). The measured value was determined. Document No. The value of 4 was taken as 100 and evaluated as a relative value. A larger value indicates a higher haze value and turbidity.
Evaluation of photographic performance

<Evaluation of raw preservation>
Each sample was stored for an additional 7 days under conditions of 25 ° C.-40% RH and 40 ° C.-70% RH or 50 ° C.-70% RH, and then exposed and developed by the above-described method in an environment of 25 ° C.-55% RH. An image was obtained. The conditions of 40 ° C.-70% RH and 50 ° C.-70% RH are compulsory conditions for evaluating the storage stability of the photothermographic material until it is subjected to exposure and development. Table 1 shows (A) when measured after storage at 40 ° C.-70% RH and (B) when measured after storage at 50 ° C.-70% RH.
As an evaluation of raw storage stability, changes in the minimum concentration (Dmin) were measured. The difference between the Dmin of the sample stored at 40 ° C.-70% RH (ΔDmin (A)) and the Dmin of the sample stored at 50 ° C.-70% RH with respect to Dmin of the sample stored at 25 ° C.-40% RH The difference in Dmin (ΔDmin (B)) was measured, and the rate of change was determined by the following equation. The results are shown in Table 1.
ΔDmin (%) = [ΔDmin (B) −ΔDmin (A)] / ΔDmin (A) × 100

4) Evaluation results Table 4 shows the results.

  As shown in Table 4, all the samples in which the pH of the image forming layer falls within the range of the present invention were photothermographic materials having good raw storage and coating properties. In particular, when the pH of the first non-photosensitive layer coating solution was also within the range of the present invention, the coating property was stable and the raw storage property was good.

Example 2
1) Preparation of Samples Samples 21 to 25 were prepared in the same manner as in Example 1 except that the coating solution pH of each layer was adjusted as shown in Table 5 and others were the same.
Table 5 shows the results of measuring the film surface pH of each obtained sample.
・ Measuring method of membrane surface pH:
Water at 25 ° C. was dropped onto the sample surface, and the pH after 1 minute was measured with a pH electrode (glass flat type).

2) Performance evaluation It evaluated similarly to Example 1. FIG. The evaluation results are shown in Table 6.

表６に示すように、試料の膜面ｐＨが本発明の範囲に入る試料はすべて、生保存性及び塗布性の良好な熱現像感光材料であった。

As shown in Table 6, all the samples whose film surface pH was within the range of the present invention were photothermographic materials having good raw storage and coating properties.

Example 3
1) Preparation of Sample Example 2 except that the first intermediate layer coating solution used in Samples 22 to 25 of Example 2 was not used and the pH of the second non-photosensitive coating solution was 4.1. In the same manner, samples 31 to 34 were prepared.
When the obtained samples were evaluated in the same manner as in Example 2, all of the samples showed good results in terms of coating properties and raw storage properties.

It is a figure explaining the high pressure crushing part of the dispersion apparatus which has a high pressure crushing part used for this invention. It is a figure which shows an example which performs preliminary dispersion | distribution and this dispersion | distribution with a single dispersion | distribution apparatus by switching of a switching valve. It is a figure which shows an example which each performs preliminary dispersion | distribution and this dispersion | distribution with the dispersion | distribution apparatus provided separately.

Explanation of symbols

11 High Pressure Crushing Unit 12 High Pressure Crushing Unit A0 Supply Pot P1 Auxiliary Pump B0 Check Valve P2 Auxiliary Pump C0 Check Valve D0 Switching Valve E Preliminary Dispersion Orifice F Main Dispersion Orifice A1 Supply Pot A2 Supply Pot P3 Auxiliary Pump P4 High Pressure Pump B1 Check valve C1 Check valve D1 Switching valve B2 Check valve C2 Check valve D2 Switching valve

Claims (16)

An image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder and at least one non-photosensitive layer on the side farther from the support are coated on at least one surface of the support. A method for producing a photothermographic material comprising:
1) The non-photosensitive layer is formed from a coating solution having setability,
2) A method for producing a photothermographic material, wherein the coating solution pH for forming the image forming layer is 6.0 or more and 8.2 or less.   2. The method for producing a photothermographic material according to claim 1, wherein the pH of the non-photosensitive layer coating solution is 4.0 or more and 6.0 or less.   The manufacturing method according to claim 1 or 2, wherein the pH difference between the coating solution of the highest pH layer and the coating solution of the lowest pH of each layer coating solution is 4 or less. 4. The method for producing a photothermographic material according to claim 1, wherein the image forming layer and the image forming layer are applied by simultaneous multilayer coating.   The method for producing a photothermographic material according to claim 1, wherein the image forming layer coating solution has a pH of 7.0 or more and 7.5 or less.   6. The method for producing a photothermographic material according to claim 2, wherein the non-photosensitive layer coating solution has a pH of 4.5 or more and 5.0 or less.   7. The photothermographic material according to claim 1, wherein a film surface pH of the surface having the image forming layer of the photothermographic material is 4.0 or more and 6.0 or less. Material manufacturing method.   8. The method for producing a photothermographic material according to claim 7, wherein the film surface pH of the surface having the image forming layer of the photothermographic material is from 5.2 to 5.9.   9. The method for producing a photothermographic material according to claim 1, wherein the photothermographic material is applied with an aqueous solvent.   10. The method for producing a photothermographic material according to claim 9, wherein 50% by mass or more of the binder is a polymer latex.   The method for producing a photothermographic material according to claim 10, wherein the polymer latex has a monomer component having an acid group in an amount of 1% by mass to 20% by mass.   The method for producing a photothermographic material according to claim 9, wherein the polymer latex has a glass transition point (Tg) of −10 ° C. or more and 70 ° C. or less.   A second non-photosensitive layer is provided between the image forming layer and the non-photosensitive layer, and 50% by mass or more of the binder of the second non-photosensitive layer is formed from a polymer latex. The method for producing a photothermographic material according to any one of claims 1 to 12.   14. The method for producing a photothermographic material according to claim 1, wherein the pH of the second non-photosensitive layer coating solution is 6.0 or more and 8.2 or less.   15. The method for producing a photothermographic material according to claim 1, wherein the pH of the second non-photosensitive layer coating solution is 7.0 or more and 7.5 or less.   A photothermographic material produced by the production method according to any one of claims 1 to 15.

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