JP2005283935A - Heat developable photosensitive material, method for manufacturing the same and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having a high silver iodide content, high sensitivity and improved raw stock preservability; a method for manufacturing the material; and an image forming method. <P>SOLUTION: The heat developable photosensitive material has at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on at least one surface of a support, wherein (1) the photosensitive silver halide comprises a tabular host grain portion and at least one epitaxial bonding portion, and (2) the epitaxial bonding portion is formed in the presence of a site director. The method for manufacturing the material and the image forming method are also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photothermographic material, a method for producing the same, and an image forming method. In particular, the photothermographic material is highly sensitive, low fogging and excellent in preservability by using silver halide having a high silver iodide content. The present invention relates to a material, a manufacturing method thereof, and an image forming method.

  In recent years, in the medical field and the printing plate making field, dry development of photographic development processing is strongly desired from the viewpoint of environmental protection and space saving. In these areas, digitization has progressed, and image information is captured and stored on a computer, stored, and processed if necessary, and output to photosensitive materials by laser image setter or laser imager where necessary by communication. However, systems for developing and creating images on the spot are rapidly spreading. As a photosensitive material, it is necessary to form a clear black image that can be recorded by laser exposure with high illuminance and has high resolution and sharpness. As such digital imaging recording materials, various hard copy systems using pigments and dyes such as inkjet printers and electrophotography are distributed as general image forming systems, but the diagnostic ability is determined like medical images. It is unsatisfactory in terms of image quality (sharpness, graininess, gradation, color tone) and recording speed (sensitivity), and has not yet reached a level that can replace the conventional silver salt film for wet development.

  Thermal image forming systems using organic silver salts are already known. This system has an image forming layer in which a reducible silver salt (eg, organic silver salt), photosensitive silver halide, and, if necessary, a toning agent for controlling the color tone of silver is dispersed in a binder matrix. Yes.

  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. As a result, a black silver image is formed in the exposed area. The photothermographic material is disclosed in many documents, and Fuji Medical Dry Imager FM-DPL has been put on the market as a medical image forming system.

  In such an image forming system using an organic silver salt, since there is no fixing step, silver halide remains in the film even after heat development, and thus essentially has two major problems.

  One of them was deterioration in image storage stability after development processing, particularly printout when exposed to light. As a means for improving this printout, a method using silver iodide is known. Compared to silver bromide or silver iodobromide having an iodine content of 5 mol% or less, it has the characteristic of being extremely difficult to print out, and has the possibility of drastically solving this problem. However, the silver iodide grains known so far are extremely insensitive and far below the sensitivity that can be used in real systems. In addition, if a means for preventing recombination of photoelectrons and holes is applied in order to improve the sensitivity, there is a problem that characteristics excellent in printout are lost.

  As means for increasing the sensitivity of silver iodide photographic emulsions, Journal of Photographic Science, Vol. 8, 119 (1960), Vol. 28, 163 (1980), Photographic Science and Engineering, Vol. 5, 216 (1961) etc. were known to be sensitized by immersion in a halogen acceptor such as sodium nitrite, pyrogallol, hydroquinone, or an aqueous silver nitrate solution, or by sulfur sensitization with pAg7.5. . However, even with these, the effect was insufficient in practical use.

  Another problem was that the film was clouded and became translucent to opaque due to light scattering by the remaining silver halide, which deteriorated the image quality. In order to solve this problem, means for reducing the white turbidity due to silver halide by reducing the addition amount as much as possible by making photosensitive silver halide fine particles (0.15 μm to 0.08 μm in a practical area) Has been adopted as a practical means. However, this compromise further reduced sensitivity and white turbidity was not completely resolved, leaving the emulsion left haze in the film.

  In the case of the wet development processing method, the remaining silver halide is removed by processing with a fixing solution containing a silver halide solvent after the development processing. As the silver halide solvent, various inorganic and organic compounds capable of forming a complex with silver ions are known. In the past, attempts have been made to incorporate similar fixing means in dry heat development processing. For example, it has been proposed to incorporate a compound capable of forming a complex with silver ions into a film and solubilize silver halide by heat development (usually called fixing). This relates to silver halide, and it is necessary to post-heat for fixing, and the heating condition is a high temperature of 155 ° C. to 160 ° C., and the system is difficult to fix. In addition, another sheet (fixing sheet) containing a compound capable of forming a complex with silver ions is prepared, and the photothermographic material is thermally developed to form an image, which is then superposed on the fixing sheet and heated to remain. It has also been proposed to dissolve and remove silver halide, but because it is two sheets, the processing process becomes complicated and it becomes difficult to ensure the operational stability of the process, and it is necessary to discard the fixing sheet after processing. It is an obstacle from a practical point of view.

In addition to the above, as a fixing method in thermal development, a method in which a silver halide fixing agent is encapsulated in microcapsules and the fixing agent is released by thermal development to act is proposed. It is difficult to design for effective release. A method of fixing using a fixing solution after heat development has also been proposed, but it is not suitable for complete dry processing in that wet processing is required.
As described above, any of the conventionally known methods for improving the turbidity of a film has a great adverse effect and has a great difficulty in practical use.

  On the other hand, attempts have been made to apply the above-mentioned photothermographic material to a photographic material. The photographic photosensitive material mentioned here is not for writing image information by scanning exposure with a laser beam or the like, but for recording an image by surface exposure. Conventionally, it is commonly used in the field of wet-developable photosensitive materials, and in medical applications, various plate-making films for printing, such as direct or indirect X-ray films and mammographic films, industrial recording films, or films for photographing with general cameras are known Yes. For example, a photothermographic material for double-coated X-rays using a blue fluorescent intensifying screen, a photothermographic material using silver iodobromide tabular grains, or a silver chloride content having a (100) main plane A medical photosensitive material in which high tabular grains are coated on both sides of a support is also disclosed in the patent literature. The double-side coated photothermographic material is also disclosed in other patent documents. However, in all cases, the sensitivity was insufficient.

  Thus, a photosensitive silver halide having a high silver iodide content and a practical level of sensitivity has not been known. Furthermore, it is not known at all for photothermographic materials.

JP 2001-5995 A Japanese Patent Laid-Open No. 11-133531

  SUMMARY OF THE INVENTION An object of the present invention is to provide a photothermographic material having high sensitivity and low fog and excellent in preservability, a method for producing the same, and an image forming method, using silver halide having a high silver iodide content. That is.

The above object of the present invention has been achieved by the following means.
<1> A method for producing a photothermographic material having at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support, wherein (1) The photosensitive silver halide has a tabular host grain portion and at least one epitaxial junction, and (2) the photothermographic material is formed in the presence of a site director. Method.
<2> The method for producing a photothermographic material according to <1>, wherein the photosensitive silver halide has a silver iodide content of 40 mol% or more.
<3> The method for producing a photothermographic material according to <1> or <2>, wherein the site director is at least one synthetic polymer selected from polyvinyl alcohol and derivatives thereof.
<4> The method for producing a photothermographic material according to <1> or <2>, wherein the site director is at least one compound selected from dyes capable of adsorbing to silver halide.
<5> The method for producing a photothermographic material according to <1> or <2>, wherein the site director is at least one compound selected from mercapto compounds.
<6> The method for producing a photothermographic material according to any one of <1> to <5>, wherein an average silver iodide content of the epitaxial junction is 10 mol% or less.
<7> The method for producing a photothermographic material according to any one of <1> to <6>, wherein a surface silver iodide content of the epitaxial junction is 15 mol% or less.
<8> The method for producing a photothermographic material according to any one of <1> to <7>, wherein the epitaxial junction is formed through at least two grain formation processes having different temperatures.
<9> The method for producing a photothermographic material according to <6>, wherein the first particle forming step is 60 ° C. or higher, and the second particle forming step is 50 ° C. or lower.
<10> The method for producing a photothermographic material according to <8> or <9>, wherein the first grain formation step is 1 mol% or more and 5 mol% or less of the amount of silver in the host part.
<11> The photothermographic material according to any one of <1> to <10>, wherein the silver halide content of the silver halide in the epitaxial junction is 70 mol% or more. Method.
<12> The method for producing a photothermographic material according to any one of <1> to <11>, wherein chemical sensitization is performed at less than 47 ° C. after the formation of the epitaxial junction.
<13> The method for producing a photothermographic material according to any one of <1> to <12>, wherein the tabular grain has an aspect ratio of 5 or more.
<14> The method for producing a photothermographic material according to any one of <1> to <13>, wherein an average sphere equivalent diameter of the tabular grains is from 0.3 μm to 5.0 μm. .
<15> The method for producing a photothermographic material according to any one of <1> to <14>, wherein the tabular grains have an average thickness of 0.3 μm or less.
<16> The method for producing a photothermographic material according to any one of <1> to <15>, comprising a silver iodide complex forming agent.
<17> The method for producing a photothermographic material according to any one of <1> to <16>, wherein the photothermographic material contains a nucleating agent.
<18> A photothermographic material produced by the production method according to any one of <1> to <17>.
<19> The photothermographic material according to <18>, wherein the photothermographic material is subjected to X-ray exposure in close contact with a fluorescent intensifying screen including a phosphor in which 50% or more of emitted light has a wavelength of 350 nm to 420 nm. Image forming method.
<20> The image forming method according to <19>, wherein the phosphor is a divalent Eu-activated phosphor.
<21> The image forming method according to <20>, wherein the phosphor is a divalent Eu-activated barium halide phosphor.

  The present inventors have found that the sensitivity can be improved by using a tabular silver halide having at least one epitaxial junction, but the sensitivity improving effect is smaller than expected. As a result of earnest analysis of the cause, one part was that the epitaxial junction was not controlled to which part of the tabular host grain to be joined, and that it was distributed at various sites. We found out that even if silver bromide was used for the epitaxial junction, iodine ions diffused from the high silver iodide tabular grains in the host part and that part of the silver bromide was changed to silver iodide. It was. As a result of further research, the inventors have found a technique for joining at a position having the largest sensitizing effect by using a site director, leading to the invention <1>. The inventors have found preferable conditions and have arrived at the inventions of <2> to <5>. By improving the grain forming conditions of the epitaxial junction, it was found that a more preferable effect can be obtained by suppressing silver iodide in the epitaxial junction, and the present inventions <6> to <11> have been achieved. In addition, the inventors have found that the effects of the present invention are remarkably exhibited particularly in combination with chemical sensitization, leading to the invention <12>. Further preferable conditions were found and the inventions <13> to <17> were reached. <18> is a photothermographic material produced by these production methods. <19> to <21> are inventions based on the discovery of a more preferable image forming method using the photothermographic material.

  According to the present invention, there are provided a photothermographic material having high sensitivity, low fog and excellent raw storage, a method for producing the same, and an image forming method using silver halide having a high silver iodide content.

The present invention is described in detail below.
1. Photosensitive silver halide The photosensitive silver halide according to the present invention comprises 50% or more of the total projected area of tabular grains, and the tabular grains have a host portion and at least one epitaxial junction, and the epitaxial junction The part is formed in the presence of a site director.
The photosensitive silver halide grain of the present invention will be described in detail.

(Tabular grains)
In the present invention, a silver halide tabular grain (hereinafter referred to as “tabular grain”) refers to a silver halide grain having two opposing parallel main surfaces. These tabular grains are often hexagonal, triangular, square, rectangular or round when they are viewed from a direction perpendicular to the main surface. There is no problem even if it exists. However, in order to uniformly perform epitaxial sensitization between grains, it is preferable that the size and shape be monodispersed as much as possible.

  In the present invention, a tabular grain means a silver halide grain having an aspect ratio (equivalent circle diameter / thickness of main plane) of 2 or more. The equivalent-circle diameter of the tabular grains is obtained, for example, by taking a transmission electron micrograph by the replica method to obtain the diameter of a circle having an area equal to the projected area of each grain (equivalent circle diameter). The thickness cannot be calculated simply from the length of the shadow of the replica due to epitaxial deposition. However, it can be calculated by measuring the length of the shadow of the replica before epitaxial deposition. Alternatively, even after epitaxial deposition, the sample coated with tabular grains can be cut and easily taken by taking an electron micrograph of the cross section. If the aspect ratio is 2 or more, it corresponds to the tabular grains in the present invention, but preferably the aspect ratio is 5 or more, more preferably the aspect ratio is 7 or more, and most preferably the aspect ratio is 10 or more.

1) Halogen composition The tabular grains in the present invention are not limited, but the silver iodide content is particularly preferably 40 mol% or more. The rest is not particularly limited, and can be selected from silver halides such as silver chloride and silver bromide, or organic silver salts such as silver thiocyanate and silver phosphate, and silver bromide and silver chloride are particularly preferable. . By using silver halide having a composition having a high silver iodide content, it is possible to design a preferable photothermographic material in which image storage stability after development processing, in particular, an increase in fog due to light irradiation is remarkably small.

  The halogen composition of the tabular grains in the present invention is more preferably that the silver iodide content is 60 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, and most preferably 90 mol% or more and 100 mol%. % Or less.

  In the tabular grains in the present invention, the distribution of the halogen composition of the host tabular 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 also be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles. A core high silver iodide structure having a high silver iodide content in the core part or a shell high silver iodide structure having a high silver iodide content in the shell part can also be preferably used. In designing a photothermographic material in which image storability after development processing, in particular, an increase in fog due to light irradiation is extremely small, the higher the silver iodide content of the host tabular grains, the more preferable, and more preferably 80 mol% or more It is 100 mol% or less, More preferably, it is 90 mol% or more and 100 mol% or less.

The halogen composition of the epitaxial junction in the present invention is silver bromide, silver chloride, or silver chlorobromide. The silver bromide content is preferably 50 mol% or more, more preferably the silver bromide content is 70 mol% or more, and still more preferably 90 mol% or more.
The average silver iodide content of the epitaxial junction is preferably as low as 10 mol% or less. More preferably, they are 0.1 mol% or more and 7 mol% or less, More preferably, they are 0.1 mol% or more and 5 mol% or less, More preferably, they are 0.1 mol% or more and 3 mol% or less.
The surface silver iodide content of the epitaxial junction is also preferably as low as 15 mol% or less. More preferably, they are 0.1 mol% or more and 10 mol% or less, More preferably, they are 0.1 mol% or more and 8 mol% or less, More preferably, they are 0.1 mol% or more and 5 mol% or less.

  As a method for examining the halogen composition in silver halide crystals, an X-ray diffraction method is generally known. The X-ray diffraction method is described in detail in Basic Analytical Chemistry Course 24 “X-ray diffraction” and the like. Typically, the diffraction angle is determined by a powder method using Cu Kβ rays as a radiation source.

When the diffraction angle 2θ is obtained, the lattice constant a is obtained from the black equation as follows.
2 dsin θ = λ
d = a / (h ² + k ² + l ² ) ^1/2
Here, 2θ is the diffraction angle of the (hkl) plane, λ is the X-ray wavelength, and d is the surface spacing of the (hkl) plane. Since the relationship between the halogen composition of the silver halide solid solution and the lattice constant a is already known (for example, described in TH James, “The Theory of Photographic Process. 4th Ed.”, Macmillian New York) Once the lattice constant is known, the halogen composition can be determined.

  However, since the X-ray diffraction method cannot distinguish between the host part and the epitaxial part of the tabular grain, the halogen composition of the epitaxial part cannot be determined. In the present invention, the halogen composition of the epitaxial portion is measured by the following method.

<Measuring method of average silver iodide content of epitaxial part>
In the present invention, the average silver iodide content of the epitaxial portion of silver halide grains can be measured by the following method.
The tabular silver halide grains in the silver halide photographic light-sensitive material are taken out by treating the light-sensitive material with a proteolytic enzyme and centrifuging it. The particles are redispersed and placed on a copper mesh with a support film. In order to prevent the alteration of the particles, it is preferable that the amount of proteolytic enzyme used is as small as possible. In some cases, a method may be used in which the photosensitive material is cut into layers using a microtome, and the particles together with the binder are taken out. The particles taken out in this manner are observed from the main plane direction, and the epitaxial region projected out of the extension of the host side is scanned with a beam focused to a spot diameter of 2 nm or less with an analytical electron microscope. The silver iodide content of the epitaxial part is measured. The silver iodide content can be calculated by treating silver halide grains having a known content in the same manner as a calibration curve and obtaining the ratio of Ag intensity and halogen intensity in advance. As the electron gun of the analytical electron microscope, a field emission type electron gun having a higher electron density is more suitable than a thermionic type electron gun, and the silver iodide content of a minute epitaxial portion can be easily analyzed. By this method, the average silver iodide content of the epitaxial part in which the information in the thickness direction when observed from the main plane direction is averaged can be obtained.

<Method for measuring surface silver iodide content of epitaxial portion>
In the present invention, the surface silver iodide content of the epitaxial portion of silver halide grains can be measured by the following method.
The tabular silver halide grains in the silver halide photographic light-sensitive material are taken out by treating the light-sensitive material with a proteolytic enzyme and centrifuging it. In order to prevent the alteration of the particles, it is preferable that the amount of proteolytic enzyme used is as small as possible. The particles are coated on a triacetyl cellulose support, then embedded using a resin, and a section having a thickness of about 50 nm is cut with an ultramicrotome and placed on a copper mesh with a support film. In some cases, a method may be used in which the photosensitive material is cut into layers using a microtome, and the particles together with the binder are taken out. A predetermined portion of the grains taken out in this manner is scanned with a beam focused to a spot diameter = 2 nm or less with an analytical electron microscope, and the silver iodide content in one epitaxial portion is measured. The silver iodide content can be calculated by treating silver halide grains having a known content in the same manner as a calibration curve and obtaining the ratio of Ag intensity and halogen intensity in advance. As the electron gun of the analytical electron microscope, a field emission type electron gun having a higher electron density is more suitable than a thermionic type electron gun, and the silver iodide content of a minute epitaxial portion can be easily analyzed. By this method, the local surface silver iodide content of the epitaxial part can be obtained.

  The silver iodide in this invention can take arbitrary beta phase and (gamma) phase content rate. The β phase refers to a high silver iodide structure having a hexagonal wurtzite structure, and the γ phase refers to a high silver iodide structure having a cubic zinc blend structure. The γ-phase content referred to here is C.I. R. It is determined using the method proposed by Berry. This method is determined based on the peak ratio of the silver iodide β phase (100), (101), (002) and the γ phase (111) in the powder X-ray diffraction method. Physical Review, Volume 161, No. 3, p. Reference may be made to 848-851 (1967).

2) Epitaxial junction The tabular grain in the present invention has at least one epitaxial junction on the surface of the grain.
In the present invention, the epitaxial junction is formed in the presence of a site director. In the present invention, the site director means what promotes the epitaxial formation of host particles at specific positions, and is also called a site indicator.
Specifically, the site director in the present invention can form an epitaxial junction at the apex of the host particle. That is, the epitaxial portion is preferably joined to at least one apex portion of the particle. More preferably, it is joined to all apexes.

  Conventionally, it is known to use a site director to control the grain shape of silver iodobromide grains. It has been known mainly for the formation of silver iodobromide tabular grains having a low silver iodide content. The site director in the present application is very effective even in host grains of silver iodide having a high content of 40 mol%, and is formed by controlling the junction position when forming an epitaxial junction. Moreover, the silver iodide having a high content of 40 mol% has a function of suppressing the diffusion of iodine ions from the host grain at the epitaxial junction in the host grain, which is more than that required by a conventional site director. It also has. Furthermore, the site director in the present application also has a function of preventing deformation of the shape of the host particles.

  In the present invention, the vertex portion is a sector formed by one vertex when the tabular grain is viewed from the direction perpendicular to the main surface, and this vertex and two sides constituting this vertex are formed, Of these two sides, it means a part in a sector having a radius of 1/3 of the length of the shorter side. When the shape of the main surface of the tabular grain is a rounded triangular or hexagonal shape, or a square or rectangular shape, the vertices and sides of the main surface are virtual triangles formed by extending each side, Hexagonal or square and rectangular shapes, respectively, apexes and sides.

The epitaxial junction preferably has at least one dislocation line. The number of dislocation lines in the epitaxial junction of the present invention is preferably as the number is increased. Dislocation lines may be introduced unintentionally into the epitaxial junction due to the difference in halogen composition between the host tabular grain and the epitaxial junction, but the intended dislocation line is introduced by controlling the epitaxial deposition conditions. More preferred. At this time, it is preferable that dislocation lines are not substantially observed in the host tabular grains. The coexistence of dislocation lines in the host tabular grains and the epitaxial junction is not preferable because the latent image formation efficiency is lowered and the sensitivity is lowered.
In a tabular grain having two or more epitaxial junctions, it is not always necessary to have dislocation lines in each epitaxial junction.

In the present invention, the dislocation lines at the epitaxial junction are preferably in the form of a network.
A mesh dislocation line is a dislocation line in which a plurality of dislocation lines that cannot be counted as a number are interlaced like a mesh.

  The dislocation lines of tabular grains are described in, for example, J.A. F. Hamilton, Photo. Sci. Eng. 11, 57, (1967) and T.W. Shiozawa, J. et al. Soc. Photo. Sci. It can be observed by a direct method using a transmission electron microscope at a low temperature described in Japan, 35, 213, (1972). In other words, the silver halide grains taken out carefully so as not to apply a pressure that causes dislocation lines to the grains from the emulsion are placed on a mesh for electron microscope observation to prevent damage (printout, etc.) due to electron beams. Observation is performed by a transmission method in a state where the tube is cooled. At this time, the thicker the particle, the more difficult it is to transmit the electron beam. Therefore, it is possible to observe more clearly using a high-pressure type electron microscope (200 kV or more for a particle having a thickness of 0.25 μm). . From the photograph of the particles obtained by such a method, the position and number of dislocation lines for each particle when viewed from the direction perpendicular to the main surface can be obtained.

  In the present invention, the size of the epitaxial portion is preferably 1 mol% to 60 mol%, more preferably 3 mol% to 50 mol% in terms of the number of moles of silver ions with respect to the host particle portion. More preferably, it is 5 mol%-30 mol%, Most preferably, it is 10 mol%-20 mol%.

3) Grain size For the silver halide of high silver iodide used in the present invention, a sufficiently large grain size necessary to achieve high sensitivity can be selected.
In the present invention, the average sphere equivalent diameter of silver halide is preferably 0.3 μm or more and 5.0 μm or less, and more preferably 0.35 μm or more and 3.0 μm or less. The equivalent sphere diameter here means the diameter of a sphere having the same volume as the volume of one silver halide grain. As a measuring method, it can obtain | require by calculating | requiring the particle | grain volume from each projected area and thickness observed with the electron microscope, and converting into the sphere of the same volume as the volume.
In the present invention, the preferred average silver halide thickness is 0.02 μm or more and 0.3 μm or less, and more preferably 0.02 μm or more and 0.15 μm or less.

4) 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 method described in JP-A No. 11-352627 and Japanese Patent Application No. 2000-42336 are also preferable.
Regarding the method of forming tabular grains of silver iodide, the methods described in JP-A-59-119350 and 59-119344 are preferably used.

The method for preparing tabular host emulsion grains in the present invention will be described below.
The preparation of the host tabular grains in the present invention may be obtained by any grain formation method comprising three steps of nucleation, ripening and growth, or two steps of nucleation and growth, or nucleation and growth are one. Those obtained by a particle forming method integrated in two steps are also preferably used.

In the nucleation step, nucleation can be performed in a short time with a low pI. Where pI is the logarithm of the reciprocal of the I ⁻ ion concentration of the system. In the present invention, particularly preferably, an aqueous silver nitrate solution and an aqueous halogen solution are added with stirring in the presence of gelatin at a temperature of 20 ° C. to 80 ° C. At this time, the pI of the system is preferably 3 or less, and the pH is preferably 7 or less. The concentration of the aqueous silver nitrate solution is preferably 1.5 mol / liter or less. By using the above nucleation method, it is easy to form an inner epitaxial emulsion.

  The aging step is preferably performed at a temperature of 50 ° C. or higher and 80 ° C. or lower. Further, additional gelatin is preferably added immediately after nucleation until the end of ripening. Particularly preferred gelatin is phthalated gelatin. The use of these gelatins facilitates the preparation of the epitaxial emulsion in the present invention.

In the growth step of the present invention, it may be carried out by simultaneous addition of a solution containing a halogen ion containing iodide and a solution containing AgNO ₃ , preferably a silver nitrate aqueous solution, a halogen aqueous solution containing iodide and a silver iodide fine grain emulsion. Alternatively, it is performed by adding them simultaneously. The silver iodide fine grain emulsion may be substantially silver iodide and may contain silver bromide and / or silver chloride as long as it can form a mixed crystal. 100% silver iodide is preferred. Silver iodide can have a β layer, a γ layer and an α layer or α layer-like structure as described in US Pat. No. 4,672,026 in its crystal structure. In the present invention, the crystal structure is not particularly limited, but a mixture of a β layer and a γ layer, more preferably a β layer is used. The silver iodide fine grain emulsion may be formed immediately before the addition described in US Pat. No. 5,004,679 or the like, and may be any one that has undergone a normal water washing step. What passed through the water washing process of this is used. The silver iodide fine grain emulsion can be easily formed by the method described in US Pat. No. 4,672,026. A double jet addition method of an aqueous silver salt solution and an aqueous iodide salt solution in which the particle formation is carried out with a constant pI value at the time of grain formation is preferred. The type, concentration, presence / absence of silver halide solvent, type, concentration, etc. of the protective colloid agent such as temperature, pI, pH, and gelatin are not particularly limited, but the grain size is 0.1 μm or less, more preferably 0.8. A thickness of 07 μm or less is convenient for the present invention. The particle shape cannot be completely specified because it is a fine particle, but the variation coefficient of the particle size distribution is preferably 25% or less. In particular, when it is 20% or less, the effect of the present invention is remarkable. Here, the size and size distribution of the silver iodide fine grain emulsion are obtained by placing the silver iodide fine grains on a mesh for observation with an electron microscope and directly observing them by a transmission method instead of the carbon replica method. This is because the measurement error becomes large in the observation by the carbon replica method because the particle size is small. The particle size is defined as the diameter of a circle having a projected area equal to the observed particle. The particle size distribution is also determined by using this equivalent projected area circle diameter. The silver iodide fine particles most effective in the present invention have a grain size of 0.06 μm or less and 0.02 μm or more, and a grain size distribution variation coefficient of 18% or less.

  The most preferably used in the growth step of the present invention is similar to the method described in JP-A-2-188874, and an ultrafine grain emulsion of silver iodide, silver bromoiodide, or silver chloroiodide prepared immediately before addition is used. When the tabular grains are grown, they are continuously added to dissolve the ultrafine grain emulsion to grow tabular grains. An external mixer for preparing an ultrafine emulsion has a strong stirring ability, and an aqueous silver nitrate solution, an aqueous halogen solution and gelatin are added to the mixer. Gelatin can be added in advance or immediately before mixing with an aqueous silver nitrate solution and / or an aqueous halogen solution, or an aqueous gelatin solution alone. The gelatin preferably has a molecular weight smaller than that of a normal one, particularly preferably 10,000 to 50,000. Gelatin in which the amino group is modified by 90% or more to phthalation, succination or trimellitization and / or oxidation-treated gelatin with a reduced methionine content is particularly preferably used. Most preferably, phthalated modified gelatin is used, and the use of this method facilitates the preparation of the epitaxial emulsion in the present invention.

<Gelatin>
In preparing the host tabular grains in the present invention, various gelatins can be used as a silver halide protective colloid. It is necessary to maintain a good dispersion state of the silver halide emulsion in the coating solution containing an organic silver salt, and it is preferable to use low molecular weight gelatin having a molecular weight of 10,000 to 100,000. It is more preferable to use phthalated gelatin. These gelatins may be used at the time of grain formation and / or at the time of dispersion after desalting, but it is particularly preferable to use at the time of grain formation.

  In preparing the host tabular grains in the present invention, various silver halide solvents or surface adsorbents can be used. Although it is possible to freely select grains to obtain grains having a desired grain size and aspect ratio including temperature, pH, and pAg, it is easy to prepare the epitaxial emulsion in the present invention that the host tabular grains are as monodispersed as possible. become.

5) Method for preparing epitaxial junction The method for preparing an epitaxial junction in the present invention will be described below.
Epitaxial deposition may be performed immediately after the formation of the host tabular grains, or may be performed after ordinary desalting is performed after the formation of the host tabular grains. Preferably, epitaxial deposition is performed after normal desalting. Preferably, the host tabular grain emulsion in the present invention is washed with water for desalting and dispersed in a newly prepared protective colloid. As the protective colloid to be dispersed after desalting of the host tabular emulsion in the present invention, it is advantageous to use gelatin.

<Site Director>
The epitaxial junction in the present invention is prepared in the presence of a site director. Although the site director may be used alone, it is more preferable to use a plurality of combinations. Although the epitaxial deposition position can be controlled by selecting the amount and type of use, it is generally preferable to add 40% to 90% of the saturated coverage. Further, these adsorbates can be further added after the epitaxial deposition. It is also possible to suppress mixed crystallization by using an adsorbate on the host particles as a function of the site director.

The site director that can be used in the present invention can be strongly adsorbed by silver halide grains. Synthetic polymers such as polyvinyl alcohols, polyvinyl pyrrolidones, polyvinyl acetates, dextrans, polyethyleneiminopropionic acids, polyethyleneimines, polyalkyleneaminotriazoles, generally known cyanine dyes, merocyanine dyes , Dyes such as rhodacyanine dyes, mercapto compounds, bispidinium salt compounds, and the like, but are not limited thereto.
More preferably, the site director is at least one synthetic polymer selected from polyvinyl alcohol and derivatives thereof, or at least one compound selected from a dye capable of adsorbing to silver halide and a mercapto compound.

  Polyvinyl alcohol and derivatives thereof preferably have a mass average molecular weight (Mw) of 4400 or more and may contain any of nonionic, anionic, and cationic functional groups, but the ratio of vinyl alcohol units to the total units is 90 More than mol%. The polymer is known to strongly adsorb to AgX particles and have a strong protective colloid ability, but is characterized in that the adsorption balance with gelatin can be easily changed during particle formation by pH, pAg and temperature. At this time, it is preferable to change the molecular weight of the polymer depending on the type of gelatin used. Alternatively, it is possible only by controlling the adsorptive power by pH. Further, the polymer is characterized by the fact that it does not absorb visible light, so that emulsion design can be performed by separating spectral sensitization and effects described later.

  The dye is generally selected from dyes such as cyanine dyes, merocyanine dyes, and rhodacyanine dyes that are widely known. More preferably, the silver halide grains having a high silver iodide content in the present invention are used. A dye excellent in blue light absorption is used. In addition to the large absorption of blue light, which is an inherent light absorption region of silver halide due to the high silver iodide gun rate, it is preferable to select a dye having near light absorption in terms of high sensitivity.

The AgX emulsion of the present invention is preferably prepared using a mercapto compound represented by the general formula (V). In the general formula (V), Z represents a heterocyclic ring having at least one of —SO ₃ M, —COOR ¹ , —OH and —NHR ² directly or indirectly, and M represents a hydrogen atom, an alkali metal atom, or four Represents a quaternary ammonium group or a quaternary phosphonium group, R ¹ represents a hydrogen atom, an alkali metal atom, or an alkyl group having 1 to 6 carbon atoms, R ² represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, —COR ³ , —COOR ³ or —SO ₂ R ³ is represented, and R ³ represents a hydrogen atom, an aliphatic group or an aromatic group. Here, “having the above substituents indirectly” means that the above substituents are bonded to the heterocyclic ring formed by Z via a divalent group, or on the ring condensed with the heterocyclic ring formed by Z. Examples include those to which the above substituent is bonded.

  The main feature is that the emulsion can be designed by separating the spectral sensitization and the effect described later by not absorbing the visible light of the mercapto compound.

<Temperature conditions>
In the present invention, in order to reduce the silver iodide content of the epitaxial junction, it is preferable to form the epitaxial junction in a two-stage grain formation process at different temperatures. That is, the first particle forming step is performed at a relatively high temperature, and the second particle forming step is performed at a relatively low temperature. The temperature of the first particle forming step is preferably 60 ° C to 80 ° C, more preferably 70 ° C to 80 ° C. The temperature of the second particle forming step is preferably 25 ° C to 50 ° C, more preferably 25 ° C to 40 ° C.
In this invention, it is preferable to perform a 1st particle formation process at 1 mol%-10 mol% of the amount of host silver by silver mol number, More preferably, it is 1 mol%-5 mol%.

  If the temperature of the first particle formation step is lower than this, epitaxial junctions are not formed more uniformly between the particles, and at a temperature higher than this, diffusion of iodine ions from the host particles to the epitaxial junction is very large. It is not preferable. Even if the temperature of the second particle forming step is lower than the temperature of the first particle forming step, the particle growth of the epitaxial junction proceeds, so that it is as low as possible within that range to suppress the diffusion of iodine ions from the host particles, It is preferable for forming an epitaxial junction having a low silver halide content.

<Washing, desalting, etc.>
The temperature for washing with water can be selected according to the purpose, but is preferably selected within the range of 5 ° C to 50 ° C. Although pH at the time of water washing can also be chosen according to the objective, it is preferred to choose between 2-10. More preferably, it is the range of 3-8. Although pAg at the time of water washing can also be selected according to the objective, it is preferable to select between 4-10. In particular, in the case of host tabular grains having a high silver iodide content, it is preferable to set appropriately because minute morphological changes that occur during washing have a great influence on the later-described epitaxial deposition. The washing method can be selected from a noodle washing method, a dialysis method using a semipermeable membrane, a centrifugal separation method, a coagulation sedimentation method, and an ion exchange method. In the case of the coagulation sedimentation method, a method using a sulfate, a method using an organic solvent, a method using a water-soluble polymer, a method using a gelatin derivative and the like can be selected.

  At the time of dispersion after desalting, pH, pAg, gelatin type and concentration, and viscosity are selected for the preparation of the epitaxial emulsion in the present invention. In this invention, Preferably they are 5 or more and 8 or less. The pH is more preferably from 5.3 to 7, particularly preferably from 5.5 to 6.8. By setting this pH, epitaxial deposition can be performed uniformly between particles, and the effect of the present invention becomes remarkable. As the gelatin species, it is particularly preferable as an epitaxial deposition condition of the present invention that phthalated gelatin is used.

  In the present invention, the host tabular grains are preferably physically ripened at a high temperature before epitaxial deposition. By performing physical ripening at a high temperature, the top of the host tabular grains tends to have a slightly rounded shape, and the epitaxial deposition near the top is facilitated in the subsequent epitaxial deposition step.

  It is supersaturation, temperature, and pAg that have the greatest influence on the epitaxial deposition conditions. The epitaxial deposition conditions for having a uniform epitaxial junction are preferably higher supersaturation and higher temperature. However, if the degree of supersaturation is too high, the number of epitaxial junctions other than the top of the host tabular grains will increase. .

  In the present invention, the pAg at the time of epitaxial deposition is preferably 4.8 or more and 9.5 or less, more preferably 6.1 or more and 7.8 or less.

  In the present invention, it is preferable to intentionally perform conversion during epitaxial deposition. Conversion is the conversion of the halogen composition by adding a halogen with lower solubility to the epitaxial junction that has already been deposited. For example, after performing epitaxial deposition with a high silver chloride content, an epitaxial junction with a high silver bromide content can be formed by adding a solution containing potassium bromine.

In the present invention, the epitaxial junction may be formed by adding a solution containing a halogen ion and a solution containing AgNO ₃ simultaneously or separately, and adding AgCl fine particles, AgBr fine particles, and AgI fine particles having a particle diameter smaller than that of the host tabular grains. Alternatively, they may be added in combination with the addition of such mixed crystal particles. A preferred method is the simultaneous addition of a solution containing halogen ions and a solution containing AgNO ₃ .

When the AgNO ₃ solution is added, the addition time is preferably 15 seconds or more and 40 minutes or less, and particularly preferably 30 seconds or more and 20 minutes or less. In order to form the epitaxial emulsion in the present invention, the concentration of the silver nitrate solution added is preferably 1.5 mol / liter or less, and more preferably 0.5 mol / liter or less. At this time, it is necessary to efficiently stir the system, and it is preferable that the viscosity of the system is low.

  In the present invention, the size of the epitaxial junction is preferably from 1 mol% to 60 mol%, more preferably from 3 mol% to 50 mol% in terms of the number of moles of silver ions with respect to the host particle portion. More preferably, it is 5 mol%-30 mol%, Most preferably, it is 10 mol%-20 mol%. If the amount is too small, an epitaxial emulsion cannot be prepared. If the amount is too large, the effect of epitaxial sensitization becomes small.

  In the case of an epitaxial emulsion, it is generally preferable to stabilize the shape because the epitaxial junction tends to undergo a shape change due to recrystallization. As a means for stabilizing the shape of the epitaxial junction of the present invention, it is preferable to add an adsorbate such as a water-soluble mercapto compound immediately after the epitaxial deposition and cause the epitaxial junction to adsorb. Can be stabilized. The addition amount is preferably used in a range that does not interfere with the chemical sensitization described later according to the size and shape of the particles.

6) Spectral sensitization The photosensitive silver halide in the present invention may be spectrally sensitized.
Spectral sensitizing dyes are those that can spectrally sensitize silver halide grains in the desired wavelength region when adsorbed on silver halide grains, and advantageously use sensitizing dyes having spectral sensitivity suitable for the spectral characteristics of the exposure light source. You can choose. The epitaxial emulsion in the present 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, particularly preferably 300 nm to 450 nm. Regarding the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A-11-65021, compounds represented by the general formula (II) of JP-A-10-186572, and general formulas (I) of JP-A-11-119374 ) And the dye described in Example 5 of U.S. Pat. Nos. 5,510,236 and 3,871,887, JP-A-2-96131, JP-A-59-48753. Dyes disclosed in Japanese Patent No. 2000-83865, Japanese Patent Application No. 2000-86865, Japanese Patent Application No. 2000-102560, Japanese Patent Application No. 2000-205399, etc. It is described in. These sensitizing dyes may be used alone or in combination of two or more.

  In the epitaxial emulsion of 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.

7) Heavy Metal The photosensitive silver halide grain in the invention may contain a metal or metal complex of Group 6 to Group 13 of the Periodic Table (showing Groups 1 to 18). More preferably, it can contain a metal or metal complex of Group 6 to Group 10 of the Periodic Table. Preferable specific examples of the group 6 to group 13 metal or metal complex of the periodic table are rhodium, ruthenium, iridium, and iron. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol with ^respect to 1 mol of silver. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.

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

  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.

Further, regarding a metal atom (for example, [Fe (CN) ₆ ] ⁴⁻ ), a silver halide emulsion desalting method and a chemical sensitization method which can be contained in the silver halide grains used in the present invention, JP-A No. 11-101. 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.

8) Chemical Sensitization The photosensitive silver halide used in the present invention is preferably chemically sensitized by at least one of a chalcogen sensitization method, a gold sensitization method and a reduction sensitization method. Examples of the chalcogen sensitizing method include a sulfur sensitizing method, a selenium sensitizing method, and a tellurium sensitizing method.

In sulfur sensitization, unstable sulfur compounds are used. The unstable sulfur compounds described in Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure 307, 307105, and the like can be used.
Specifically, thiosulfate (for example, hypo), thioureas (for example, diphenylthiourea, triethylthiourea, N-ethyl-N ′-(4-methyl-2-thiazolyl) thiourea, carboxymethyltrimethylthiourea), thioamides (Eg, thioacetamide), rhodanines (eg, diethyl rhodanine, 5-benzylidene-N-ethyl rhodanine), phosphine sulfides (eg, trimethylphosphine sulfide), thiohydantoins, 4-oxo-oxazolidin-2 Known sulfur compounds such as thiones, disulfides or polysulfides (for example, dimorpholine disulfide, cystine, lenthionine (1,2,3,5,6-pentathiepane)), polythionates, elemental sulfur, and active gelatin Also use Door can be. Particularly preferred are thiosulfates, thioureas and rhodanines.

  In selenium sensitization, unstable selenium compounds are used, and Japanese Patent Publication Nos. 43-13489, 44-15748, JP-A-4-25832, 4-109340, 4-271341, and 5-40324. 5-11385, Japanese Patent Application Nos. 4-202415, 4v330495, 4-333030, 5-4203, 5-4204, 5-106977, 5-236538, Selenium compounds described in JP-A-5-241642 and JP-A-5-286916 can be used.

  Specifically, colloidal metal selenium, selenoureas (for example, N, N-dimethylselenourea, trifluoromethylcarbonyl-trimethylselenourea, acetyl-trimethylselenourea), selenoamides (for example, selenoamide, N, N -Diethylphenylselenamide), phosphine selenides (eg, triphenylphosphine selenide, pentafluorophenyl-triphenylphosphine selenide), selenophosphates (eg, tri-p-tolylselenophosphate, Tri-n-butylselenophosphate), selenoketones (for example, selenobenzophenone), isoselenocyanates, selenocarboxylic acids, selenoesters, diacylselenides and the like may be used. Furthermore, non-labile selenium compounds described in JP-B Nos. 46-4553 and 52-34492, such as selenite, selenocyanate, selenazoles, and selenides can also be used. In particular, phosphine selenides, selenoureas and selenocyanates are preferred.

Specific examples of the sulfur sensitizer and selenium sensitizer used in the present invention are listed below, but the present invention is not limited to these.

  In tellurium sensitization, an unstable tellurium compound is used, and JP-A-4-224595, JP-A-4-271341, JP-A-4-3333043, JP-A-5-303157, JP-A-6-27573, JP-A-6-175258, The unstable tellurium described in JP-A-6-180478, JP-A-6-208186, JP-A-6-208184, JP-A-6-317867, JP-A-7-140579, JP-A-7-301879, JP-A-7-301880, etc. Compounds can be used.

  Specifically, phosphine tellurides (for example, butyl-diisopropylphosphine telluride, tributylphosphine telluride, tributoxyphosphine telluride, ethoxy-diphenylphosphine telluride), diacyl (di) tellurides ( For example, bis (diphenylcarbamoyl) ditelluride, bis (N-phenyl-N-methylcarbamoyl) ditelluride, bis (N-phenyl-N-methylcarbamoyl) telluride, bis (N-phenyl-N-benzylcarbamoyl) telluride, bis ( Ethoxycarbonyl) telluride), telluroureas (for example, N, N′-dimethylethylenetellurourea, N, N′-diphenylethylenetellurourea) telluramides, telluroesters, etc. may be used. In particular, diacyl (di) tellurides and phosphine tellurides are preferable. Particularly, the compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, the general formula (II) in JP-A-5-313284, Compounds represented by (III) and (IV) are more preferred.

  In particular, in the chalcogen sensitization in the present invention, selenium sensitization and tellurium sensitization are preferable, and tellurium sensitization is particularly preferable.

  In gold sensitization, P.I. Gold sensitizers described by Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure 307, No. 307105 can be used. Specifically, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide and the like, in addition to these, U.S. Pat. Nos. 2,642,361, 5,049,484, 5,049,485, 5,169,751, Gold compounds described in Japanese Patent No. 5252455 and Belgian Patent No. 691857 can also be used. P. Precious metals such as platinum, palladium, iridium, etc. other than gold described in Grafkides, Chimie et Physique Photographic (published by Paul Momtel, 1987, 5th edition), Research Disclosure 307, 307105 it can.

  Although gold sensitization can be used alone, it is preferably used in combination with the chalcogen sensitization described above. Specifically, gold sulfur sensitization, gold selenium sensitization, gold tellurium sensitization, gold sulfur selenium sensitization, gold sulfur tellurium sensitization, gold selenium tellurium sensitization, and gold sulfur selenium tellurium sensitization.

  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 chalcogen sensitizer used in the present invention varies depending on the silver halide grains used, chemical ripening conditions, etc., but is 10 ⁻⁸ mol or more and 10 ⁻¹ mol or less, preferably 10 ⁻ per mol of silver halide. ^{About 7 to} 10 ⁻² mol is used.
Similarly, the amount of the gold sensitizer used in the present invention varies depending on various conditions, but as a guideline, it is 10 ⁻⁷ mol or more and 10 ⁻² mol or less, more preferably 10 ⁻⁶ mol per mol of silver halide. The amount is 5 × 10 ⁻³ mol or less. The environmental conditions for chemically sensitizing this emulsion can be selected under any conditions, but the pAg is 8 or less, preferably 7.0 or less to 6.5 or less, particularly 6.0 or less, and the pAg is 1.5 or less. Above, preferably 2.0 or more, particularly preferably 2.5 or more, pH 3 to 10, preferably 4 to 9, temperature 20 to 95 ° C., preferably 25 to 80 It is about ℃ or less.

In the present invention, reduction sensitization can be used in combination with chalcogen sensitization or gold sensitization. In particular, it is preferably used in combination with chalcogen sensitization.
As specific compounds for reduction sensitization, ascorbic acid, thiourea dioxide, and dimethylamine borane are preferable. In addition, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. It is preferable to use it. 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 also preferable by ripening while maintaining the pH of the emulsion at 8 or higher or pAg at 4 or lower, and reduction sensitization by introducing a single addition portion of silver ions during grain formation. Is also preferable.
The amount of reduction sensitizer added varies depending on various conditions, but as a guideline, it is 10 ⁻⁷ mol or more and 10 ⁻¹ mol or less, more preferably 10 ⁻⁶ mol or more and 5 × 10 5 mol per mol of silver halide. ^-2 mol or less.

A thiosulfonic acid compound may be added to the silver halide emulsion used in the present invention by the method shown in European Patent Publication No. 293,917.
The photosensitive silver halide grains in the invention are preferably chemically sensitized by at least one of gold sensitization and chalcogen sensitization from the viewpoint of designing a high-sensitivity photothermographic material.

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

  The one-electron oxidant produced by one-electron oxidation contained in the light-sensitive material of the present invention is a compound selected from the following types 1 and 2 that can emit one or more electrons.

(Type 1)
A compound in which a one-electron oxidant produced by one-electron oxidation can further emit 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) (JP-A-2003-114487) 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), and 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). In the general formula (2)), the general formula (8) (Synonymous with general formula (1) described in Japanese Patent Application No. 2003-25886) or chemical reaction formula (1) (synonymous with chemical reaction formula (1) described in Japanese Patent Application No. 2003-33446) Among the compounds that can cause the above, there can be mentioned a 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 general formulas (1) and (2), RED ₁ and RED ₂ each independently 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- or 6-membered aromatic ring (including an aromatic heterocycle) or a hexahydro form together with the carbon atom (C) and RED ₁ Represents. R ₂ , R ₃ and R ₄ each independently represents a hydrogen atom or a substituent. Lv ₁ and Lv ₂ each independently represent a leaving group. ED represents an electron donating group.

In the general formulas (3), (4) and (5), Z ₁ represents an atomic group capable of forming a 6-membered ring with a nitrogen atom and two carbon atoms of the benzene ring. _{R 5, R 6, R 7} , R 9, R 10, R 11, R 13, R 14, R 15, R 16, R 17, R 18, R 19 each independently represent a hydrogen atom or a substituent . R ₂₀ represents a hydrogen atom or a substituent. When R ₂₀ represents a group other than an aryl group, R ₁₆ and R ₁₇ are bonded to each other to form an aromatic ring or an aromatic heterocycle. R ₈ and R ₁₂ represent a substituent that can be substituted on the benzene ring, m1 represents an integer of 0 to 3, and m2 represents an integer of 0 to 4. Lv ₃ , Lv ₄ and Lv ₅ represent a leaving group.

In the general formulas (6) and (7), RED ₃ and RED ₄ each independently represent a reducing group. R _{21 to} R ₃₀ each independently represents a hydrogen atom or a substituent. Z ₂ represents —CR ₁₁₁ R ₁₁₂ —, —NR ₁₁₃ —, or O—. R ₁₁₁ and R ₁₁₂ each independently represents a hydrogen atom or a substituent. _R113 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group.

In General Formula (8), RED ₅ is a reducing group and represents an arylamino group or a heterocyclic amino group. R ₃₁ represents a hydrogen atom or a substituent. X 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. Lv ₆ is a leaving group and represents a carboxy group or a salt thereof, or a hydrogen atom.

The compound represented by the general formula (9) is a compound that undergoes a bond formation reaction represented by the chemical reaction formula (1) by being further oxidized after two-electron oxidation accompanied by decarboxylation has occurred. In the chemical reaction formula (1), R ₃₂ and R ₃₃ represent a hydrogen atom or a substituent. Z ₃ represents a group which forms a 5- or 6-membered heterocycle with C═C. Z ₄ represents a group that forms a 5- or 6-membered aryl group or heterocyclic group with C═C. M represents a radical, a radical cation, or a cation. In the general formula (9), ₃₂ , R ₃₃ and Z ₃ have the same meanings as those in the chemical reaction formula (1). Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C.

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 compound of type 2 and further with one subsequent bond formation reaction, a compound represented by the general formula (10) is disclosed. A compound capable of causing a 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). 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.

General formula (10): RED ₆ -QY

In the general formula (10), RED ₆ represents a reducing group that is oxidized one electron. Y reacts with a one-electron oxidant formed by one-electron oxidation of RED ₆ to form a new bond, a carbon-carbon double bond site, a carbon-carbon triple bond site, an aromatic group site, or Reactive group containing a non-aromatic heterocyclic moiety of a benzo-fused ring. Q represents a linking group for linking RED ₆ and Y.

The compound represented by the general formula (11) is a compound that causes a bond formation reaction represented by the chemical reaction formula (1) by being oxidized. In the chemical reaction formula (1), R ₃₂ and R ₃₃ each independently represent a hydrogen atom or a substituent. Z ₃ represents a group that forms a 5- or 6-membered heterocycle with C═C. Z ₄ represents a group that forms a 5- or 6-membered aryl group or heterocyclic group with C═C. Z ₅ represents a group which forms a 5- or 6-membered cyclic aliphatic hydrocarbon group or heterocyclic group together with C—C. M represents a radical, a radical cation, or a cation. In the general formula (11), R ₃₂ , R ₃₃ , Z ₃ and Z ₄ have the same meanings as in the chemical reaction formula (1).

  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 those 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 (trialkylphosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group, etc.). Be 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 counter anions of quaternary salts include halogen ions, carboxylate ions, sulfonate ions, sulfate ions, perchlorate ions, carbonate ions, nitrate ions, 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).

In 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) — each independently 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.

  Specific examples of the compounds represented by type 1 and type 2 are listed below, but the present invention is not limited thereto.

  The compounds of type 1 and type 2 in the present invention may be used at any time during the preparation of the emulsion and during the photosensitive material production process. For example, at the time of particle formation, desalting step, chemical sensitization, and before coating. Moreover, it can also add in several steps in these processes. The addition position is preferably from the end of particle formation to before the desalting step, at the time of chemical sensitization (from immediately before the start of chemical sensitization to immediately after the end), and before application, more preferably at the time of chemical sensitization and before application.

  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 the emulsion layer, but may be added to the protective layer or intermediate layer together with the emulsion layer and diffused during coating. The timing of addition of these compounds is preferably 1 × 10 ⁻⁹ mol or more and 5 × 10 ⁻² mol or less, more preferably 1 × 10 ⁻⁸ mol, per mol of silver halide, regardless of before or after the sensitizing dye. It is contained in the silver halide emulsion layer at a ratio of 2 × 10 ⁻³ mol or less.

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 is a cation such as an alkali metal, alkaline earth metal or heavy metal (Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ag ⁺ , Zn ²⁺ etc.), ammonium ion Examples thereof include a heterocyclic group containing a quaternized nitrogen atom, a phosphonium ion, and the like.
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 ring having a -S- group, a -Se- group, a -Te- group, or a = N- group as a partial structure of the heterocyclic ring, which can 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, and oxazole group. , Benzothiophene 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 a rotating disk voltammetry technique, specifically, a sample is dissolved in a solution of methanol: pH 6.5 Briton-Robinson buffer = 10%: 90% (volume%), and nitrogen gas is used for 10 minutes. , A glassy carbon rotating disk electrode (RDE) 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. Can be measured at 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 10,000, more preferably between 120 and 1,000, and 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.

  Further, 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 a silver halide emulsion layer, it may be added to the adjacent protective layer or intermediate layer together with the silver halide emulsion 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 × 10 ⁻⁶ mol to 1 mol, preferably 1 × 10 ⁻⁵ mol, per mol of photosensitive silver halide. The amount is 5 × 10 ⁻¹ mol or less, more preferably 1 × 10 ⁻⁴ mol or more and 1 × 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.

2. Photothermographic material 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. . Moreover, it is preferable to have a surface protective layer on the image forming layer, or a back layer or a back protective layer on the opposite side.

1) Photosensitive silver halide The above-mentioned photosensitive silver halide can be used for the photothermographic material in the invention.
The photosensitive silver halide emulsion may be used alone or in combination of two or more (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits, and those having different chemical sensitization conditions). May be. 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.

The addition amount of the photosensitive silver halide, when expressed by the amount of coated silver per photosensitive material 1 m ^2, is preferably 0.03 g / m ² or more 0.6 g / m ² or less, 0.05 g / m ² or more It is more preferably 0.4 g / m ² or less, most preferably 0.07 g / m ² or more and 0.3 g / m ² or less, and the photosensitive silver halide is used per 1 mol of the organic silver salt. Is preferably from 0.01 mol to 0.5 mol, more preferably from 0.02 mol to 0.3 mol, and still more preferably from 0.03 mol to 0.2 mol.

The photosensitive silver halide and the organic silver salt may be prepared independently and then mixed. Alternatively, the organic silver salt may be prepared in the presence of a photosensitive silver halide to prepare an organic silver salt containing the photosensitive silver halide. In this invention, it is preferable to prepare each independently and to mix after that.
Regarding the mixing method and mixing conditions of the separately prepared photosensitive silver halide and organic silver salt, the silver halide grains and organic silver salt that were prepared respectively were mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, homogenizer. Etc., or a method of preparing an organic silver salt by mixing photosensitive silver halide that has been prepared at any timing during the preparation of the organic silver salt, etc., but the effect of the present invention is sufficient As long as it appears in, there is no particular limitation. Moreover, mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a preferred method for adjusting photographic characteristics.

  The preferred addition time of the photosensitive silver halide to the image-forming layer coating solution is from 180 minutes before coating to immediately before, preferably from 60 minutes to 10 seconds before coating. There is no particular limitation as long as the effect appears sufficiently. 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.

2) Compound that effectively reduces visible light absorption derived from photosensitive silver halide after heat development In the present invention, visible light absorption derived from photosensitive silver halide is performed after heat development compared to before heat development. It is preferable to contain a compound that reduces the amount of the chemical.
In the present invention, it is particularly preferable to use a silver iodide complex-forming agent as a compound that practically reduces visible light absorption derived from photosensitive silver halide after heat development.

(Description of silver iodide complex forming agent)
In the present invention, it is preferable to use a compound that can substantially reduce the spectral absorption intensity in the ultraviolet-visible range derived from photosensitive silver halide by heat development, and particularly preferably a silver iodide complex forming agent. .
The silver iodide complex-forming agent can contribute to a Lewis acid-base reaction in which at least one of a nitrogen atom or a sulfur atom in a compound donates electrons to a silver ion as a coordination atom (electron donor: Lewis base). is there. The stability of the complex is defined by the sequential stability constant or the total stability constant, but depends on the combination of silver ion, iodide ion, and the silver complexing agent. As a general guideline, a large stability constant can be obtained by means such as a chelate effect due to intramolecular chelate ring formation and an increase in the acid-base dissociation constant of the ligand.

  The ultraviolet-visible absorption spectrum of the photosensitive silver halide can be measured by a transmission method or a reflection method. If the absorption derived from other compounds added to the photothermographic material overlaps with the absorption of the photosensitive silver halide, the difference spectrum or the removal of other compounds with a solvent can be used alone or in combination. The UV-visible absorption spectrum of photosensitive silver halide can be observed.

The silver iodide complex forming agent in the present invention is preferably a 5- to 7-membered heterocyclic compound containing at least one nitrogen atom. When the compound does not have a mercapto group, sulfide group or thione group as a substituent, the nitrogen-containing 5- to 7-membered heterocyclic ring may be saturated or unsaturated, and has other substituents. It may be. Moreover, the substituents on the heterocycle may be bonded to each other to form a ring.
Examples of preferred 5-7 membered heterocyclic compounds include pyrrole, pyridine, oxazole, isoxazole, thiazole, isothiazole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, indole, isoindole, indolizine, quinoline, isoquinoline, benzo Imidazole, 1H-imidazole, quinoxaline, quinazoline, cinnoline, phthalazine, naphthyridine, purine, pteridine, carbazole, acridine, phenanthridine, phenanthroline, phenazine, phenoxazine, phenothiazine, benzothiazole, benzoxazole, benzimidazole, 1,2, 4-triazine, 1,3,5-triazine, pyrrolidine, imidazolidine, pyrazolidine, piperidine, piperazine, morpholine, in Phosphorus, and the like isoindoline. More preferably pyridine, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, indole, isoindole, indolizine, quinoline, isoquinoline, benzimidazole, 1H-imidazole, quinoxaline, quinazoline, cinnoline, phthalazine, 1,8-naphthyridine, 1, Examples thereof include 10-phenanthroline, benzimidazole, benzotriazole, 1,2,4-triazine, 1,3,5-triazine and the like. Particularly preferable examples include pyridine, imidazole, pyrazine, pyrimidine, pyridazine, phthalazine, triazine, 1,8-naphthyridine, 1,10-phenanthroline, and the like.

These rings may have a substituent, and the substituent may be any substituent as long as it does not adversely affect photographic properties. Preferred examples include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched, or cyclic alkyl group, including a bicycloalkyl group or an active methine group), an alkenyl group, or an alkynyl group. Group, aryl group, heterocyclic group (regarding the position of substitution), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy group or a salt thereof, oxalyl group, oxamoyl group, cyano group, carbonimidoyl group (Carbonimidoyl group), formyl group, hydroxy group, alkoxy group ( Ethyleneoxy group Or an aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, Aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, ammonio group, oxamoylamino Group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, nitro group, heterocyclic group containing a quaternized nitrogen atom (for example, pyridinio group, imidazolio group, Kinori O group, isoquinolinio group), isocyano group, imino group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfur group Examples include a famoyl group or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyloxy group, a phosphinylamino group, and a silyl group. Here, the active methine group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group here means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, An alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, or a carbonimidoyl group (Carbonimidoyl group) is meant. Here, the two electron withdrawing groups may be bonded to each other to form a cyclic structure. The salt means a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion. These substituents may be further substituted with these substituents.
These heterocycles may be further condensed with other rings. Further, the substituent is an anionic group _{^{(e.g., -CO 2 -, -SO 3 -}} , -S - , etc.), the nitrogen-containing heterocyclic cation (e.g., pyridinium, etc. triazolium) and Thus, an inner salt may be formed.

When the heterocyclic compound is a pyridine, pyrazine, pyrimidine, pyridazine, phthalazine, triazine, naphthyridine or phenanthroline derivative, a tetrahydrofuran / water (3/2) mixed solution of the conjugate acid of the nitrogen-containing heterocyclic moiety in the acid dissociation equilibrium of the compound The acid dissociation constant (pKa) at 25 ° C. is more preferably 3 to 8. More preferably, the pKa is 4 to 7.
Such a heterocyclic compound is preferably a pyridine, pyridazine or phthalazine derivative, and particularly preferably a pyridine or phthalazine derivative.

  When these heterocyclic compounds have a mercapto group, sulfide group, or thione group as a substituent, pyridine, thiazole, isothiazole, oxazole, isoxazole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, triazine, triazole, thiadiazole or oxadioxide Diazole derivatives are preferable, and thiazole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, triazine, and triazole derivatives are particularly preferable.

  For example, a compound represented by the following general formula (1) or general formula (2) can be used as the silver iodide complex forming agent.

In Formula (1), R ¹¹ and R ¹² represents a hydrogen atom or a substituent. In general formula (2), R ²¹ and R ²² represents a hydrogen atom or a substituent. However, R ¹¹ and R ¹² are not both hydrogen atoms, and R ²¹ and R ²² are not both hydrogen atoms. Examples of the substituent herein include those described as the substituent of the nitrogen-containing 5- to 7-membered heterocyclic silver iodide complex forming agent.

  Moreover, the compound represented by the following general formula (3) can also be preferably used.

In the general formula (3), R ^{31 to} R ³⁵ each independently represent a hydrogen atom or a substituent. Examples of the substituent represented by R ³¹ -R ³⁵ include those described above as the substituent of the nitrogen-containing 5-7-membered heterocyclic silver iodide complex forming agent. When the compound represented by the general formula (3) has a substituent, preferred substitution positions are R ^{32 to} R ³⁴ . R ^{31 to} R ³⁵ may be bonded to each other to form a saturated or unsaturated ring. Preferred are a halogen atom, alkyl group, aryl group, carbamoyl group, hydroxy group, alkoxy group, aryloxy group, carbamoyloxy group, amino group, acylamino group, ureido group, (alkoxy or aryloxy) carbonylamino group, and the like. .

  The compound represented by the general formula (3) has an acid dissociation constant (pKa) at 25 ° C. of 3 to 8 in a tetrahydrofuran / water (3/2) mixed solution of a conjugate acid of a pyridine ring portion. It is preferably 4 to 7, and particularly preferably.

  Furthermore, the compound represented by General formula (4) is also preferable.

In the general formula (4), R ⁴¹ -R ⁴⁴ each independently represent a hydrogen atom or a substituent. R ^{41 to} R ⁴⁴ may be bonded to each other to form a saturated or unsaturated ring. Examples of the substituent represented by R ^{41 to} R ⁴⁴ include those described as the substituent of the nitrogen-containing 5 to 7-membered heterocyclic silver iodide complex forming agent. Preferred groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, hydroxy groups, alkoxy groups, aryloxy groups, heterocyclic oxy groups, and the formation of phthalazine rings by benzo condensed rings. When a hydroxyl group is substituted on the carbon adjacent to the nitrogen atom of the compound represented by the general formula (4), an equilibrium exists with pyridazinone.

The compound represented by the general formula (4) more preferably forms a phthalazine ring represented by the following general formula (5), and the phthalazine ring further has at least one substituent. It is particularly preferable. Examples of R ⁵¹ -R ⁵⁶ in the general formula (5) include those described as substituents of the nitrogen-containing 5- to 7-membered heterocyclic silver iodide complex forming agent. More preferred substituents include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, hydroxy groups, alkoxy groups, aryloxy groups and the like. An alkyl group, an alkenyl group, an aryl group, an alkoxy group, and an aryloxy group are preferable, and an alkyl group, an alkoxy group, and an aryloxy group are more preferable.

  A compound represented by the following general formula (6) is also a preferred form.

In the general formula (6), R ⁶¹ -R ⁶³ each independently represent a hydrogen atom or a substituent. Examples of the substituent represented by R ⁶² include those described as the substituent of the nitrogen-containing 5 to 7-membered heterocyclic silver iodide complex forming agent.

  A compound represented by the following general formula (7) is preferably used.

In the general formula (7), R ⁷¹ -R ⁷² each independently represent a hydrogen atom or a substituent. L represents a divalent linking group. n represents 0 or 1. Examples of the substituent represented by R ^{71 to} R ⁷² include an alkyl group (including a cycloalkyl group), an alkenyl group (including a cycloalkenyl group), an alkynyl group, an aryl group, a heterocyclic group, an acyl group, and aryloxycarbonyl. Examples include a group, an alkoxycarbonyl group, a carbamoyl group, an imide group, and a composite substituent containing these. The divalent linking group represented by L is preferably a linking group having a length of 1 to 6 atoms, more preferably 1 to 3 atoms, and may further have a substituent.

  One of the compounds preferably used is a compound represented by the general formula (8).

In the general formula (8), R ^{81 to} R ⁸⁴ each independently represents a hydrogen atom or a substituent. Examples of the substituent represented by R ^{81 to} R ⁸⁴ include an alkyl group (including a cycloalkyl group), an alkenyl group (including a cycloalkenyl group), an alkynyl group, an aryl group, a heterocyclic group, an acyl group, and an aryloxycarbonyl. Examples include a group, an alkoxycarbonyl group, a carbamoyl group, and an imide group.

  More preferable among the silver iodide complex-forming agents are compounds represented by the general formulas (3), (4), (5), (6) and (7), and the general formula (3), The compound represented by (5) is particularly preferred.

  Although the preferable example of the silver iodide complex formation agent in this invention is given to the following, this invention is not limited to these.

  The silver iodide complex-forming agent in the present invention may be a common compound with the color tone agent when it functions as a conventionally known color tone agent. The silver iodide complex-forming agent in the present invention can be used in combination with a toning agent. Two or more silver iodide complex forming agents may be used in combination.

  The silver iodide complex-forming agent in the present invention is preferably present in the film in a state separated from the photosensitive silver halide, such as being present in the film in a solid state. It is also preferable to add to the adjacent layer. It is preferable to adjust the melting point of the compound to an appropriate range so that the silver iodide complex-forming agent in the present invention melts when heated to the heat development temperature.

  In the present invention, the absorption intensity of the ultraviolet-visible absorption spectrum of the photosensitive silver halide after heat development is preferably 80% or less, more preferably 40% or less, compared with that before heat development. It is particularly preferable that

The silver iodide complex-forming agent in the present invention 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.

As the solid fine particle dispersion method, the powder of the silver iodide complex forming agent in the present invention is dispersed in a suitable 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 ultrasonic waves. And a method of producing a solid dispersion. 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).
The silver iodide complex-forming agent in the present invention is preferably used as a solid dispersion.

  The silver iodide complex forming agent in the present invention is preferably used in the range of 1 mol% to 5000 mol%, more preferably in the range of 10 mol% to 1000 mol%, relative to the photosensitive silver halide. More preferably, it is the range of 50 mol% or more and 300 mol% or less.

3) Organic silver salt The non-photosensitive organic silver salt used in the present invention is relatively stable to light. However, in the presence of an exposed photosensitive silver halide and a reducing agent, it is 80 ° C or higher. A silver salt that forms a silver image when heated. The organic silver salt may be any organic material containing a source capable of reducing silver ions. As for such non-photosensitive organic silver salt, paragraph numbers 0048 to 0049 of JP-A-10-62899, page 18 line 24 to page 19 line 37 of European Patent Publication No. 0803764A1, European Patent Publication. No. 0968212A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, and the like. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids (having 10 to 30, preferably 15 to 28 carbon atoms) are preferred. Preferable examples of the organic silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and a mixture thereof. In the present invention, among these organic silver salts, it is preferable to use organic acid silver having a silver behenate content of 50 mol% to 100 mol%. In particular, the silver behenate content is preferably 75 mol% or more and 98 mol% or less.

The shape of the organic silver salt that can be used in the present invention is not particularly limited, and may be a needle shape, a rod shape, a flat plate shape, or a flake shape.
In the present invention, scaly organic silver salts are preferred. In the present specification, the scaly organic silver salt is defined as follows. The organic silver salt is observed with an electron microscope, the shape of the organic silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (even though c is the same as b) Good)), and calculate with the shorter numbers a and b, and find x 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 of c / b is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, still more preferably 1 or more and 3 or less, and particularly preferably 1 or more and 2 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. Indicates the following. 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 of obtaining from 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.

  Known methods and the like can be applied to the production and dispersion method of the organic acid silver used in the present invention. For example, Japanese Patent Application Laid-Open No. 10-62899, European Patent Publication No. 0803763A1, European Patent Publication No. 0968212A1, Japanese Patent Application Laid-Open No. 11-349591, Japanese Patent Application Laid-Open No. 2000-7683, Japanese Patent Application Laid-Open No. JP-A-2001-163889-90, JP-A-11-203413, Japanese Patent Application Nos. 2000-90093, 2000-195621, 2000-191226, 2000-213813, 2000-214155, 2000-. Reference may be made to 191226 and the like.

  In the present invention, an organic silver salt aqueous dispersion and a photosensitive silver salt aqueous dispersion can be mixed to produce a photosensitive material. Mixing two or more organic silver salt water dispersions and two or more photosensitive silver salt water dispersions when mixing is a method preferably used for adjusting photographic properties.

The organic silver salt in the present invention can be used in a desired amount, but the silver amount is preferably 0.1 g / m ² or more and 5 g / m ² or less, more preferably 1 g / m ² or more and 3 g / m ² or less. Particularly preferred is 1.2 g / m ² or more and 2.5 g / m ² or less.

4) Reducing agent The photothermographic material of the invention contains a reducing agent for organic silver salt. The reducing agent may be any substance (preferably an organic substance) that can reduce silver ions to metallic silver. Examples of the reducing agent are disclosed in JP-A No. 11-65021, paragraph numbers 0043 to 0045, European Patent No. 0803764, p. 7, lines 34-p. 18th and 12th lines.

  A preferable reducing agent used in the present invention is a so-called hindered phenol reducing agent having a substituent at the ortho position of the phenolic hydroxyl group, or a bisphenol reducing agent. Particularly preferred are compounds 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.

Each substituent 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, 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 group that can be substituted on a benzene ring.
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, and specifically include a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, and a cyclohexyl group. Group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, methoxyethyl group and the like. More preferred are methyl group, ethyl group, propyl group, isopropyl group and t-butyl group.

X ¹ and X ¹ ′ are preferably a hydrogen atom, a halogen atom, or an alkyl group, and more preferably a hydrogen atom.

L is preferably a —CHR ¹³ — group.

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

When R ¹³ is a hydrogen atom, R ¹² and R ¹² ′ are preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group.

When R ¹³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, R ¹² and R ¹² ′ are preferably methyl groups. As the primary or secondary alkyl group having 1 to 8 carbon atoms for R ^13, a methyl group, an ethyl group, a propyl group, or an isopropyl group is more preferable, and a methyl group, an ethyl group, or a propyl group is still more preferable.

When all of R ¹¹ , R ¹¹ ′ and R ¹² , R ¹² ′ are methyl groups, R ¹³ is preferably a secondary alkyl group. In this case, the secondary alkyl group of R ¹³ is preferably an isopropyl group, an isobutyl group, or a 1-ethylpentyl group, and more preferably an isopropyl group.

The reducing agent has various heat development performances depending on the combination of R ¹¹ , R ¹¹ ′, R ^12, R ¹² ′, and R ¹³ . Since these heat development performances can be adjusted by using two or more reducing agents in combination at various mixing ratios, it is preferable to use two or more reducing agents in combination depending on the purpose.

    Specific examples of the compound represented by formula (R) in the present invention are shown below, but the present invention is not limited thereto.

In the present invention, the addition amount of the reducing agent is preferably 0.01 g / m ² or more and 5.0 g / m ² or less, more preferably 0.1 g / m ² or more and 3.0 g / m ² or less, It is preferably contained in an amount of 5 mol% or more and 50 mol% or less, more preferably 10 mol% or more and 40 mol% or less with respect to 1 mol of silver on the surface having the image forming layer.

  The reducing agent in the present invention can be added to an image forming layer containing an organic silver salt and a photosensitive silver halide, and an adjacent layer thereof, but is more preferably contained in the image forming layer.

  The reducing agent in the present invention may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.

  Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically emulsifying the dispersion. The method of producing is mentioned.

  In addition, as the solid fine particle dispersion method, there is a method in which a reducing agent is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill or an ultrasonic wave to produce a solid dispersion. Be mentioned. A dispersion method using a sand mill is preferable. 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. The aqueous dispersion can contain a preservative (eg, benzoisothiazolinone sodium salt).

  Particularly preferred is a solid particle dispersion method of a reducing agent, in which 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 1 μm are added. Is preferred. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

5) Development accelerator In the photothermographic material of the invention, a sulfonamide represented by the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234, or the like is used as a development accelerator. Phenol compounds, hindered phenol compounds represented by the general formula (II) described in JP-A No. 2001-92075, JP-A Nos. 10-62895 and 11-15116, etc. Hydrazine compounds represented by formula (I), general formula (D) of JP-A No. 2002-156727 and general formula (1) described in JP-A No. 2002-278017, JP-A No. 2001-264929 A phenolic or naphtholic compound represented by the general formula (2) described in the book is preferably used. Moreover, the phenol type compound described in Unexamined-Japanese-Patent No. 2002-311533 and Unexamined-Japanese-Patent No. 2002-341484 is also preferable. In particular, naphthol compounds described in JP-A No. 2003-66558 are preferable. These development accelerators are used in the range of 0.1 mol% or more and 20 mol% or less, preferably 0.5 mol% or more and 10 mol% or less, more preferably 1 mol% or more with respect to the reducing agent. The range is 5 mol% or less. 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 emulsified dispersion. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high-boiling solvent that is solid at room temperature and a low-boiling auxiliary solvent, or as a so-called oilless emulsified dispersion that does not use a high-boiling solvent. It is preferable to add.
In the present invention, among the above development accelerators, hydrazine compounds described in JP-A Nos. 2002-156727 and 2002-278017 and naphthol compounds described in JP-A No. 2003-66558 are used. Is more preferable.

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

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

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

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

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

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

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

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

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

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

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

6) Hydrogen-bonding compound In the present invention, the reducing agent has an aromatic hydroxyl group (—OH) or a non-reducing compound having a group capable of forming a hydrogen bond with an amino group when it has an amino group. It is preferable to use together.

  Examples of the group capable of forming a hydrogen bond 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. 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, particularly preferred hydrogen bonding compounds are compounds 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, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group. Preferred examples of the substituent include an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, and a t-octyl group. Group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like.

Specific examples of the alkyl group represented by R ²¹ to R ²³ include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, Examples include 1-methylcyclohexyl group, benzyl group, phenethyl group, 2-phenoxypropyl group and the like.

  Examples of the aryl group include phenyl group, cresyl group, xylyl group, naphthyl group, 4-t-butylphenyl group, 4-t-octylphenyl group, 4-anisidyl group, and 3,5-dichlorophenyl group.

  Alkoxy groups include methoxy, ethoxy, butoxy, octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy, dodecyloxy, cyclohexyloxy, 4-methylcyclohexyloxy, benzyl An oxy group etc. are mentioned.

  Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, and a biphenyloxy group.

  Examples of the amino group include a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, and an N-methyl-N-phenylamino group. .

R ²¹ to R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In view of the effects of the present invention, at least one of R ²¹ to R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, R ²¹ to R ²³ are preferably 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 Japanese Patent Application Nos. 2000-192191 and 2000-19481 in addition to those described above.

  The hydrogen bonding compound in the present invention can be used in a light-sensitive material after being contained in a coating solution in the form of a solution, an emulsified dispersion, or a solid dispersed fine particle dispersion in the same manner as the reducing agent. These compounds form a complex by hydrogen bonding with a compound having a phenolic hydroxyl group in a solution state, and are isolated in a crystalline state as a complex depending on the combination of the reducing agent and the compound of the general formula (A) in the present invention. can do.

  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 hydrogen bonding compound in the present invention are mixed in a powder form, and a complex is formed at the time of dispersion by a sand grinder mill or the like using an appropriate dispersant can be preferably used.

  The hydrogen bonding compound in the present invention is preferably used in the range of 1 mol% or more and 200 mol% or less, more preferably in the range of 10 mol% or more and 150 mol% or less, further preferably 30 mol%, based on the reducing agent. The range is from mol% to 100 mol%.

7) Binder Any polymer may be used as the binder of the image forming layer in the invention as long as the glass transition temperature is 0 ° C. or higher and 80 ° C. or lower. Suitable binders are transparent or translucent and are generally colorless and are natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, and other film-forming media such as gelatins, rubbers, poly (vinyl alcohol) s , Hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrate, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) s, poly (methyl methacrylic acid) s, poly (vinyl chloride) s, poly ( Methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral) )), Poly (esters), poly ( (Letane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), poly (olefin), cellulose ester, poly (amide) . The binder may be formed from water, an organic solvent or an emulsion.

  Although the glass transition temperature of a binder is 0 degreeC or more and 80 degrees C or less, it is preferable that they are 10 degreeC or more and 70 degrees C or less, and it is more preferable that they are 15 degreeC or more and 60 degrees C or less.

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 (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, it is preferable that the image forming layer is coated 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 image forming 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 image forming layer is further added to an aqueous solvent (aqueous solvent). When it is soluble or dispersible, the performance is improved particularly when it is made of a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The most preferable form is one prepared so that the ionic conductivity is 2.5 mS / cm or less, and as such a preparation method, there is a method of performing purification treatment using a separation functional membrane after polymer synthesis.

  The aqueous solvent in which the polymer is soluble or dispersible here is a mixture of water or water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol, cellosolvs such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, ethyl acetate, and dimethylformamide.

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

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

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

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

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle 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, 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. 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.

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

-P-1; latex of -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)
-P-4; Latex of -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C)
-P-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C)
-P-6; -St (70) -Bu (27) -IA (3)-latex (crosslinkable)
-P-7; Latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
-P-8; Latex (crosslinkability) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
-Latex (crosslinkable) of P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-
-Latex (molecular weight 80,000) of P-10; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-
-P-11; latex of -VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
-P-12; -Et (90) -MAA (10)-latex (molecular weight 12000)
-P-13; Latex of -St (70) -2EHA (27) -AA (3) (molecular weight 130,000, Tg 43 ° C)
-P-14; -MMA (63) -EA (35) -AA (2) latex (molecular weight 33000, Tg 47 ° C.)
-P-15; Latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
-P-16; Latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)

  The abbreviations for the above structures represent the following monomers. MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, VC; vinyl chloride, AN; 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.), 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 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% by mass or more and 99% by mass or less. Moreover, it is preferable that the polymer latex in this invention contains acrylic acid or methacrylic acid 1 mass% or more and 6 mass% or less with respect to the sum of styrene and butadiene, More preferably, 2 mass% or more and 5 mass% or less are contained. . The polymer latex in the present invention preferably contains acrylic acid. The preferred molecular weight range is the same as described above.

  Examples of latexes of styrene-butadiene acid copolymer that are preferably used in the present invention include the 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 image forming 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 image forming layer.

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

  Such an image forming layer is usually also a photosensitive layer (image forming layer) containing a photosensitive silver halide which is a photosensitive silver salt. In such a case, all binders / silver halides are used. Is in the range of 400-5, more preferably 200-10.

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

(Preferable solvent for coating solution)
In the present invention, the solvent of the image forming layer coating solution of the light-sensitive material (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%).

8) Antifoggant Antifoggant, stabilizer and stabilizer precursor that can be used in the present invention are paragraph No. 0070 of JP-A No. 10-62899, page 20 line 57 to line 57 of EP-A-0803364A1. Examples of the patent described on page 21, line 7, compounds described in JP-A Nos. 9-281737 and 9-329864, compounds described in US Pat. No. 6,083,681, and European Patent No. 1048975 can be mentioned.

(Polyhalogen compound)
Hereinafter, preferred organic polyhalogen compounds that can be used in the present invention will be specifically described. A preferred polyhalogen compound in the present invention is a compound represented by the following general formula (H).
General formula (H)
Q- (Y) n-C (Z ₁ ) (Z ₂ ) X
In general formula (H), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 to ₁ , Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron withdrawing group.
In the general formula (H), Q is preferably an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a heterocyclic group containing at least one nitrogen atom (pyridine, quinoline group, etc.).
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, an alkyl group substituted with an electron withdrawing group, an aryl group substituted with an electron withdrawing group, a heterocyclic group, an alkyl or arylsulfonyl group, acyl Group, alkoxycarbonyl group, carbamoyl group, sulfamoyl group and the like. Particularly preferred as the electron withdrawing group are a halogen atom, a carbamoyl group and an arylsulfonyl group, and a carbamoyl group is particularly preferred.
X is preferably an electron withdrawing group. Preferred electron withdrawing groups are halogen atoms, aliphatic / aryl or heterocyclic sulfonyl groups, aliphatic / aryl or heterocyclic acyl groups, aliphatic / aryl or heterocyclic oxycarbonyl groups, carbamoyl groups, sulfamoyl groups, More preferred are a halogen atom and a carbamoyl group, and particularly preferred is a bromine atom.
Z ₁ and Z ₂ are preferably a bromine atom or an iodine atom, and more preferably a bromine atom.
Y preferably represents -C (= O) -, - SO -, - SO 2 -, - C (= O) N (R) -, - SO 2 N (R) - , more preferably -C ( ═O) —, —SO ₂ —, —C (═O) N (R) —, and particularly preferably —SO ₂ —, —C (═O) N (R) —. R here represents a hydrogen atom, an aryl group or an alkyl group, more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom.
n represents 0 or 1, and is preferably 1.
In the general formula (H), when Q is an alkyl group, preferred Y is —C (═O) N (R) —, and when Q is an aryl group or heterocyclic group, preferred Y is —SO ₂ —. is there.
In the general formula (H), a form in which residues obtained by removing a hydrogen atom from the compound are bonded to each other (generally referred to as bis type, tris type, tetrakis type) can also be preferably used.
In the general formula (H), a dissociable group (for example, a COOH group or a salt thereof, a SO ₃ H group or a salt thereof, a PO ₃ H group or a salt thereof), a group containing a quaternary nitrogen cation (for example, an ammonium group or a pyridinium group) Etc.), those having a polyethyleneoxy group, a hydroxyl group or the like as a substituent are also preferred forms.

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

As polyhalogen compounds that can be used in the present invention other than the above, US Pat. No. 3,874,946, US Pat. No. 4,756,999, US Pat. No. 5,340,712, US Pat. 119624, 59-57234, JP-A-7-2781, 7-5621, 9-160164, 9-244177, 9-244178, 9-160167, 9- 319022, 9-258367, 9-265150, 9-319022, 10-197988, 10-197989, 11-242304, JP 2000-2963, JP 2000-11270 , JP2000-284410, JP2 The compounds listed as exemplary compounds of the invention in 00-284212, JP-A-2001-33911, JP-A-2001-31644, JP-A-2001-312027, and JP-A-2003-50441 are preferably used. In particular, compounds specifically exemplified in JP-A-7-2781, JP-A-2001-33911, and JP-A-2001-312027 are preferred.
The compound represented by formula (H) in the present invention is preferably used in the range of 10 ⁻⁴ mol to 1 mol, more preferably 10 ⁻³ , per mol of the non-photosensitive silver salt in the image forming layer. It is preferable to use in the range of from 1 to 10 mol, more preferably from 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.

(Nucleating agent)
In the present invention, a nucleating agent is preferably used. By using a nucleating agent, the amount of silver necessary to obtain a constant silver image density can be reduced. Various action mechanisms of the function of decreasing can be considered, but a compound having a function of improving the covering power of developed silver is preferable. Here, the covering power of developed silver refers to the optical density per unit amount of silver.

  As the nucleating agent, a hydrazine derivative compound represented by the following general formula [H], a vinyl compound represented by the following general formula (G), a quaternary onium compound represented by the following general formula (P), the formula (A) Preferred examples include cyclic olefin compounds represented by formula (B) and general formula (C).

In the general formula [H], A0 represents an aliphatic group, an aromatic group, a heterocyclic group or a -G0-D0 group which may have a substituent, B0 represents a blocking group, and A1, A2 Both represent a hydrogen atom, or one represents a hydrogen atom and the other represents an acyl group, a sulfonyl group or an oxalyl group. Here, G0 is a -CO- group, -COCO- group, -CS- group, -C (= NG1D1) - group, -SO- group, -SO ₂ - group or -P (O) (G1D1) - group G1 represents a simple bond, —O— group, —S— group or —N (D1) — group, D1 represents an aliphatic group, an aromatic group, a heterocyclic group or a hydrogen atom; In the case where a plurality of D1 are present, they may be the same or different. D0 represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group. Preferred D0 includes a hydrogen atom, an alkyl group, an alkoxy group, an amino group, and the like.

  In the general formula [H], the aliphatic group represented by A0 is preferably one having 1 to 30 carbon atoms, particularly preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, such as methyl Group, ethyl group, t-butyl group, octyl group, cyclohexyl group, benzyl group, and these are further suitable substituents (for example, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, sulfoxy group). , Sulfonamido group, sulfamoyl group, acylamino group, ureido group, etc.).

  In the general formula [H], the aromatic group represented by A0 is preferably a monocyclic or condensed aryl group, such as a benzene ring or a naphthalene ring, and the heterocyclic group represented by A0 is a single group. A heterocyclic ring containing at least one heteroatom selected from nitrogen, sulfur and oxygen atoms is preferred as the ring or condensed ring, such as pyrrolidine ring, imidazole ring, tetrahydrofuran ring, morpholine ring, pyridine ring, pyrimidine ring, quinoline ring and thiazole ring. Benzothiazole ring, thiophene ring, and furan ring. The aromatic group, heterocyclic group, and -G0-D0 group of A0 may have a substituent. Particularly preferred as A0 are an aryl group and a -G0-D0 group.

  In the general formula [H], A0 preferably contains at least one diffusion-resistant group or silver halide adsorption group. As the anti-diffusion group, a ballast group commonly used in an immobile photographic additive such as a coupler is preferable, and as the ballast group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, phenyl, which are photographically inactive Group, phenoxy group, alkylphenoxy group and the like, and the total number of carbon atoms in the substituent portion is preferably 8 or more.

  In the general formula [H], examples of the silver halide adsorption promoting group include thiourea, thiourethane group, mercapto group, thioether group, thione group, heterocyclic group, thioamide heterocyclic group, mercapto heterocyclic group, and JP-A-64. And the adsorbing group described in -90439.

In the general formula [H], B0 represents a blocking group, preferably a -G0-D0 group, and G0 is a -CO- group, a -COCO- group, a -CS- group, a -C (= NG1D1)-group, —SO— group, —SO ₂ — group or —P (O) (G1D1) — group is represented. Preferred examples of G0 include —CO— group and —COCO— group, G1 represents a simple bond, —O— group, —S— group or —N (D1) — group, D1 represents an aliphatic group, aromatic Represents a group, a heterocyclic group or a hydrogen atom, and when a plurality of D1 are present in the molecule, they may be the same or different. D0 represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group or an arylthio group, and preferred D0 is a hydrogen atom, an alkyl group, an alkoxy group or an amino group. Etc. A1 and A2 are both hydrogen atoms, or one is a hydrogen atom and the other is an acyl group (acetyl group, trifluoroacetyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, toluenesulfonyl group, etc.), or oxalyl group (ethoxalyl). Group).

  Specific examples of the compound represented by the general formula [H] include compounds of Chemical Formula No. 12 to Chemical Formula No. 18 of H-1 to H-35, and Chemical Formula No. 20 to Chemical Formula No. 26 of H.2002-131864. Although the compound of 1-1-1 to H-4-5 is raised, it is not limited to these.

  These compounds represented by the general formulas (H-1) to (H-4) of the present invention can be easily synthesized by known methods. For example, it can be synthesized with reference to US Pat. Nos. 5,464,738 and 5,496,695.

  Other hydrazine derivatives that can be preferably used include compounds H-1 to H-29 described in U.S. Pat. No. 5,545,505 columns 11 to 20, and U.S. Pat. No. 5,464,738 columns 9 to 11. Compounds 1 to 12 described. These hydrazine derivatives can be synthesized by a known method.

  General formula (G) is demonstrated. In the general formula (G), X and R are shown in a cis form, but a form in which X and R are trans is also included in the general formula (G). The same applies to the structure display of a specific compound.

  In the general formula (G), X represents an electron withdrawing group, and W represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a halogen atom, an acyl group, a thioacyl group, an oxalyl group. , Oxyoxalyl, thiooxalyl, oxamoyl, oxycarbonyl, thiocarbonyl, carbamoyl, thiocarbamoyl, sulfonyl, sulfinyl, oxysulfinyl, thiosulfinyl, sulfamoyl, oxysulfinyl, thiosulfinyl Represents a group, sulfinamoyl group, phosphoryl group, nitro group, imino group, N-carbonylimino group, N-sulfonylimino group, dicyanoethylene group, ammonium group, sulfonium group, phosphonium group, pyrylium group, immonium group.

  R is a halogen atom, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, alkenyloxy group, acyloxy group, alkoxycarbonyloxy group, aminocarbonyloxy group, mercapto group, alkylthio group, arylthio group, heterocyclic thio Group, alkenylthio group, acylthio group, alkoxycarbonylthio group, aminocarbonylthio group, organic group or inorganic salt of hydroxyl group or mercapto group (for example, sodium salt, potassium salt, silver salt), amino group, alkylamino group , Cyclic amino group (for example, pyrrolidino group), acylamino group, oxycarbonylamino group, heterocyclic group (5- to 6-membered nitrogen-containing heterocycle such as benztriazolyl group, imidazolyl group, triazolyl group, tetrazolyl group, etc.) Ureido group, sulfo An amide group. X and W, X and R may be bonded to each other to form a cyclic structure. Examples of the ring formed by X and W include pyrazolone, pyrazolidinone, cyclopentanedione, β-ketolactone, β-ketolactam and the like.

  The general formula (G) will be further described. The electron withdrawing group represented by X is a substituent whose substituent constant σp can take a positive value. Specifically, a substituted alkyl group (such as halogen-substituted alkyl), a substituted alkenyl group (such as cyanovinyl), a substituted / unsubstituted alkynyl group (such as trifluoromethylacetylenyl, cyanoacetylenyl), a substituted aryl group (such as cyano) Phenyl, etc.), substituted / unsubstituted heterocyclic groups (pyridyl, triazinyl, benzoxazolyl, etc.), halogen atoms, cyano groups, acyl groups (acetyl, trifluoroacetyl, formyl, etc.), thioacetyl groups (thioacetyl, thioformyl, etc.) ), Oxalyl group (such as methyloxalyl), oxyoxalyl group (such as etoxalyl), thiooxalyl group (such as ethylthiooxalyl), oxamoyl group (such as methyloxamoyl), oxycarbonyl group (such as ethoxycarbonyl), carboxyl group, thiol Carbonyl group (ethylthiocarboni ), Carbamoyl group, thiocarbamoyl group, sulfonyl group, sulfinyl group, oxysulfonyl group (ethoxysulfonyl etc.), thiosulfonyl group (ethylthiosulfonyl etc.), sulfamoyl group, oxysulfinyl group (methoxysulfinyl etc.), thiosulfinyl group (Such as methylthiosulfinyl), sulfinamoyl group, phosphoryl group, nitro group, imino group, N-carbonylimino group (N-acetylimino etc.), N-sulfonylimino group (N-methanesulfonylimino etc.), dicyanoethylene group, ammonium Group, sulfonium group, phosphonium group, pyrylium group, immonium group, and the like include a heterocyclic group in which an ammonium group, sulfonium group, phosphonium group, immonium group and the like form a ring. A substituent having a σp value of 0.30 or more is particularly preferable.

  Examples of the alkyl group represented by W include methyl, ethyl, trifluoromethyl, etc., examples of the alkenyl group include vinyl, halogen-substituted vinyl, cyanovinyl, etc., examples of the alkynyl group include acetylenyl, cyanoacetylenyl, and the like as the aryl group. Nitrophenyl, cyanophenyl, pentafluorophenyl and the like, and examples of the heterocyclic group include pyridyl, pyrimidyl, triazinyl, succinimide, tetrazolyl, triazolyl, imidazolyl and benzoxazolyl. W is preferably an electron-attracting group having a positive σp value, and more preferably 0.30 or more.

  Among the substituents of R, a hydroxyl group, a mercapto group, an alkoxy group, an alkylthio group, a halogen atom, an organic or inorganic salt of a hydroxyl group or a mercapto group, and a heterocyclic group are preferable, and a hydroxyl group, more preferably An organic or inorganic salt of an alkoxy group, a hydroxyl group or a mercapto group, or a heterocyclic group is exemplified, and an organic or inorganic salt of a hydroxyl group, a hydroxyl group or a mercapto group is particularly preferred.

  Of the substituents X and W, those having a thioether bond in the substituent are preferred.

  Specific examples of the compound represented by the general formula (G) include chemical formula number 27 to chemical formula number 50-1 to 92-7 in JP-A No. 2002-131864, but are not limited thereto. Absent.

  In general formula (P), Q represents a nitrogen atom or a phosphorus atom, R1, R2, R3 and R4 each represents a hydrogen atom or a substituent, and X- represents an anion. R1 to R4 may be connected to each other to form a ring.

  Examples of the substituent represented by R1 to R4 include an alkyl group (methyl group, ethyl group, propyl group, butyl group, hexyl group, cyclohexyl group, etc.), alkenyl group (allyl group, butenyl group, etc.), alkynyl group (propargyl group). Group, butynyl group, etc.), aryl group (phenyl group, naphthyl group, etc.), heterocyclic group (piperidinyl group, piperazinyl group, morpholinyl group, pyridyl group, furyl group, thienyl group, tetrahydrofuryl group, tetrahydrothienyl group, sulfolanyl group Etc.), amino groups and the like.

  Examples of the ring that R1 to R4 may be formed by connecting to each other include a piperidine ring, a morpholine ring, a piperazine ring, a quinuclidine ring, a pyridine ring, a pyrrole ring, an imidazole ring, a triazole ring, and a tetrazole ring.

  The group represented by R1 to R4 may have a substituent such as a hydroxyl group, an alkoxy group, an aryloxy group, a carboxyl group, a sulfo group, an alkyl group, and an aryl group. R1, R2, R3 and R4 are preferably a hydrogen atom and an alkyl group.

  Examples of the anion represented by X- include inorganic and organic anions such as halogen ions, sulfate ions, nitrate ions, acetate ions, and p-toluenesulfonate ions.

  As the structure of the general formula (P), the structures described in paragraph numbers 0153 to 0163 of JP-A No. 2002-131864 are more preferable.

  Specific examples of the general formula (P) include, but are not limited to, P-1 to P-52 and T-1 to T-18 of Chemical Formula No. 53 to Chemical Formula No. 62 of JP-A No. 2002-131864. Is not to be done.

  The quaternary onium compound can be synthesized by referring to known methods. For example, the tetrazolium compound can be synthesized by referring to Chemical Reviews, vol. 55, p. The method described in 335-483 can be referred to.

  Next, the compounds represented by formulas (A) and (B) will be described in detail. In the formula (A), Z1 represents a nonmetallic atomic group that can form a 5-membered to 7-membered ring structure together with -Y1-C (= CH-X1) -C (= O)-. Z1 is preferably an atomic group selected from a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, and a hydrogen atom, and several atoms selected from these are connected to each other by a single bond or a double bond. , -Y1-C (= CH-X1) -C (= O)-form a 5- to 7-membered ring structure. Z1 may have a substituent, and Z1 itself may be part of an aromatic or non-aromatic carbocycle or an aromatic or non-aromatic heterocycle, in which case Z1 The 5-membered to 7-membered ring structure formed together with -Y1-C (= CH-X1) -C (= O)-forms a condensed ring structure.

  In the formula (B), Z2 represents a nonmetallic atomic group capable of forming a 5-membered to 7-membered ring structure together with -Y2-C (= CH-X2) -C (Y3) = N-. Z2 is preferably an atomic group selected from a carbon atom, an oxygen atom, a sulfur atom, a nitrogen atom, and a hydrogen atom, and several atoms selected from these are connected to each other by a single bond or a double bond. , -Y2-C (= CH-X2) -C (Y3) = N- forms a 5- to 7-membered ring structure. Z2 may have a substituent, and Z2 itself may be an aromatic or non-aromatic carbocyclic ring or a part of an aromatic or non-aromatic heterocyclic ring, in which case Z2 The 5-membered to 7-membered ring structure formed together with -Y2-C (= CH-X2) -C (Y3) = N- forms a condensed ring structure.

  When Z1 and Z2 have a substituent, examples of the substituent are selected from those listed below. That is, typical substituents include, for example, halogen atoms (fluorine atoms, chloro atoms, bromine atoms, or iodine atoms), alkyl groups (including aralkyl groups, cycloalkyl groups, active methine groups, etc.), alkenyl groups, alkynyls. Group, aryl group, heterocyclic group, quaternized heterocyclic group containing a nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxy group or salt thereof, sulfonylcarbamoyl A group, an acylcarbamoyl group, a sulfamoylcarbamoyl group, a carbazoyl group, an oxalyl group, an oxamoyl group, a cyano group, a thiocarbamoyl group, a hydroxy group, an alkoxy group (including a group repeatedly containing an ethyleneoxy group or a propyleneoxy group unit), Aryloxy group, heterocyclic o Si group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, N-substituted nitrogen-containing heterocyclic group, acylamino Group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, quaternary ammonio group, oxamoylamino Group, (alkyl or aryl) sulfonylureido group, acylureido group, acylsulfamoylamino group, nitro group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl or aryl) sulfonyl group, ( (Alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, acylsulfamoyl group, sulfonylsulfamoyl group or a salt thereof, a group containing a phosphate amide or phosphate ester structure, a silyl group, a stannyl group, etc. Can be mentioned. These substituents may be further substituted with these substituents.

  Next, Y3 will be described. In formula (B), Y3 represents a hydrogen atom or a substituent. When Y3 represents a substituent, specific examples of the substituent include the following groups. That is, alkyl group, aryl group, heterocyclic group, cyano group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide Group, ureido group, thioureido group, imide group, alkoxy group, aryloxy group, (alkyl, aryl, or heterocyclic) thio group and the like. These substituents may be substituted with an arbitrary substituent, and specific examples of the substituent that Z1 or Z2 may have are given.

  In the formula (A) and the formula (B), X1 and X2 are each a hydroxy group (or a salt thereof), an alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an octyloxy group, a dodecyloxy group, Cetyloxy group, t-butoxy group, etc.), aryloxy groups (eg, phenoxy group, pt-pentylphenoxy group, pt-octylphenoxy group, etc.), heterocyclic oxy groups (eg, benzotriazolyl-5-oxy) Group, pyridinyl-3-oxy group, etc.), mercapto group (or salt thereof), alkylthio group (eg, methylthio group, ethylthio group, butylthio group, dodecylthio group, etc.), arylthio group (eg, phenylthio group, p-dodecylphenylthio group) Etc.), a heterocyclic thio group (for example, 1-phenyltetrazoyl-5-thio) 2-methyl-1-phenyltriazolyl-5-thio group, mercaptothiadiazolylthio group, etc.), amino group, alkylamino group (for example, methylamino group, propylamino group, octylamino group, dimethylamino group, etc.) ), Arylamino groups (for example, anilino group, naphthylamino group, o-methoxyanilino group, etc.), heterocyclic amino groups (for example, pyridylamino group, benzotriazol-5-ylamino group, etc.), acylamino groups (for example, acetamide group, octa A noylamino group, a benzoylamino group, etc.), a sulfonamide group (for example, a methanesulfonamide group, a benzenesulfonamide group, a dodecylsulfonamide group, etc.), or a heterocyclic group.

  Here, the heterocyclic group is an aromatic or non-aromatic, saturated or unsaturated, monocyclic or condensed, substituted or unsubstituted heterocyclic group such as an N-methylhydantoyl group, N- Phenylhydantoyl group, succinimide group, phthalimide group, N, N′-dimethylurazolyl group, imidazolyl group, benzotriazolyl group, indazolyl group, morpholino group, 4,4-dimethyl-2,5-dioxo-oxazolyl Groups and the like.

Further, the salt here is an alkali metal (sodium, potassium, lithium) or alkaline earth metal (magnesium, calcium) salt, silver salt, or quaternary ammonium salt (tetraethylammonium salt, dimethylcetylbenzylammonium salt, etc.), Represents a quaternary phosphonium salt and the like. In formula (A) and formula (B), Y1 and Y2 represent —C (═O) — or —SO ₂ —.

  Preferable ranges of the compounds represented by formula (A) and formula (B) are described in paragraph Nos. 0027 to 0043 of JP-A No. 11-231459. Specific examples of the compounds of formula (A) and formula (B) include, but are not limited to, compounds 1 to 110 of Table 1 to Table 8 of JP-A No. 11-231459.

Next, the compound represented by formula (C) of the present invention will be described in detail. In general formula (C), X1 represents an oxygen atom, a sulfur atom, or a nitrogen atom. When X1 is a nitrogen atom, the bond between X1 and Z1 may be a single bond or a double bond. In the case of a single bond, the nitrogen atom may have a hydrogen atom or an arbitrary substituent. Examples of the substituent include alkyl groups (including aralkyl groups, cycloalkyl groups, and active methine groups), alkenyl groups, alkynyl groups, aryl groups, heterocyclic groups, acyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, carbamoyl groups. Group, (alkyl, aryl or heterocyclic) sulfonyl group and the like. Y1 is -C (= O) -, - C (= S) -, - SO -, - SO 2 -, - C (= NR3) -, - (R4) represents a C = group represented by N- . Z1 represents a nonmetallic atomic group capable of forming a 5- to 7-membered ring containing X1 and Y1. The atomic group forming the ring is an atomic group composed of atoms other than 2 to 4 metal atoms, and these atoms may be bonded by a single bond or a double bond, and these may be a hydrogen atom or an arbitrary substitution A group (for example, an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkylthio group, an acyl group, an amino group, or an alkenyl group) may be included. When Z1 forms a 5- to 7-membered ring containing X1 and Y1, the ring is a saturated or unsaturated heterocycle, which may be a single ring or a condensed ring. In this case, the condensed ring is formed when Y1 is a group represented by C (= NR3), (R4) C = N, and R3 or R4 is bonded to a substituent of Z1. Also good.

  In the general formula (C), R1, R2, R3, and R4 each represent a hydrogen atom or a substituent. However, R1 and R2 are not bonded to each other to form a cyclic structure.

  When R1 and R2 represent a monovalent substituent, examples of the monovalent substituent include the following groups.

  For example, halogen atom (fluorine atom, chloro atom, bromine atom or iodine atom), alkyl group (including aralkyl group, cycloalkyl group, active methine group, etc.), alkenyl group, alkynyl group, aryl group, heterocycle (heterocycle) ) Group, a quaternized heterocyclic group containing a nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxy group or a salt thereof, sulfonylcarbamoyl group, acylcarbamoyl group, A sulfamoylcarbamoyl group, a carbazoyl group, an oxalyl group, an oxamoyl group, a cyano group, a thiocarbamoyl group, a hydroxyl group (hydroxy group) or a salt thereof, an alkoxy group (including a group repeatedly containing an ethyleneoxy group or a propyleneoxy group unit), Aryloxy group, hetero Oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, N-substituted nitrogen-containing heterocyclic group, acylamino Group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, quaternary ammonio group, oxamoylamino Group, (alkyl or aryl) sulfonylureido group, acylureido group, acylsulfamoylamino group, nitro group, mercapto group or salt thereof, (alkyl, aryl, or heterocyclic) thio group, (alkyl or aryl) A group containing a sulfonyl group, an (alkyl or aryl) sulfinyl group, a sulfo group or a salt thereof, a sulfamoyl group, an acylsulfamoyl group, a sulfonylsulfamoyl group or a salt thereof, a phosphoryl group, a phosphate amide or a phosphate ester structure, A silyl group, a stannyl group, etc. are mentioned. These substituents may be further substituted with these monovalent substituents.

  Next, when R3 and R4 represent a substituent, examples of the substituent include the same substituents that R1 and R2 may have except a halogen atom. R3 and R4 may be further linked to Z1 to form a condensed ring.

  Next, a preferable thing is demonstrated among the compounds represented by general formula (C). In general formula (C), Z1 is preferably an atomic group consisting of atoms selected from 2 to 4 carbon atoms, nitrogen atoms, sulfur atoms and oxygen atoms, forming a 5- to 7-membered ring together with X1 and Y1. The heterocycle formed by Z1 together with X1 and Y1 is preferably a heterocycle having 3 to 40 total carbon atoms, more preferably 3 to 25, and most preferably 3 to 20, and Z1 is preferably at least one carbon atom. including.

In formula (C), Y1 is preferably —C (═O) —, —C (═S) —, —SO ₂ —, — (R4) C═N—, and particularly preferably —C (═O ) -, - C (= S ) -, - SO 2 - a, and most preferably -C (= O) - it is.

  In the general formula (C), when R1 and R2 represent a monovalent substituent, the monovalent substituent represented by R1 and R2 is preferably a group having 0 to 25 carbon atoms or less, that is, an alkyl group. Group, aryl group, heterocyclic group, alkoxy group, aryloxy group, heterocyclic oxy group, alkylthio group, arylthio group, heterocyclic thio group, amino group, alkylamino group, arylamino group, heterocyclic amino group, ureido group , An imide group, an acylamino group, a hydroxy group or a salt thereof, a mercapto group or a salt thereof, or an electron-withdrawing substituent. Here, the electron-withdrawing substituent is a substituent whose Hammett's substituent constant σp can take a positive value, specifically, a cyano group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group. , Sulfonamido group, imino group, nitro group, halogen atom, acyl group, formyl group, phosphoryl group, carboxy group (or salt thereof), sulfo group (or salt thereof), saturated or unsaturated heterocyclic group, alkenyl group , An alkynyl group, an acyloxy group, an acylthio group, a sulfonyloxy group, or an aryl group substituted with these electron-withdrawing groups. These groups may have an arbitrary substituent.

  In the general formula (C), when R1 and R2 represent a monovalent substituent, more preferably an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group, an amino group, Examples thereof include an alkylamino group, an arylamino group, a heterocyclic amino group, a ureido group, an imide group, an acylamino group, a sulfonamide group, a heterocyclic group, a hydroxy group or a salt thereof, a mercapto group or a salt thereof. In the general formula (C), R1 and R2 are particularly preferably a hydrogen atom, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a heterocyclic group, a hydroxy group or a salt thereof, a mercapto group or a salt thereof. In the general formula (C), most preferably one of R1 and R2 is a hydrogen atom and the other is an alkoxy group, aryloxy group, alkylthio group, arylthio group, heterocyclic group, hydroxy group or salt thereof, mercapto group or salt thereof It is.

  In the general formula (C), when R3 represents a substituent, it is preferably an alkyl group having 1 to 25 carbon atoms (including aralkyl group, cycloalkyl group, active methine group, etc.), alkenyl group, aryl group, complex Ring group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl Group, sulfosulfamoyl group, alkoxy group, aryloxy group, heterocyclic oxy group, alkylthio group, arylthio group, heterocyclic thio group, amino group and the like. Particularly preferred are an alkyl group and an aryl group.

  When R4 represents a substituent in the general formula (C), preferably an alkyl group having 1 to 25 carbon atoms in total (including an aralkyl group, a cycloalkyl group, an active methine group, etc.), an aryl group, a heterocyclic group, A quaternized heterocyclic group containing a nitrogen atom (eg, pyridinio group), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group A sulfamoyl group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an arylthio group, a heterocyclic thio group and the like are used. Particularly preferred are an alkyl group, aryl group, alkoxy group, aryloxy group, heterocyclic oxy group, alkylthio group, arylthio group, heterocyclic thio group and the like. When Y1 represents C (R4) = N, it is the carbon atom in Y1 that is bonded to the carbon atom substituted by X1 and Y1.

  Specific compounds of the general formula (C) are represented by A-1 to A-230 of Chemical Formula No. 6 to Chemical Formula No. 18 described in JP-A No. 11-133546, but are not limited to these compounds.

The addition amount of the nucleating agent is in the range of 10 ⁻⁵ to 1 mol, preferably 10 ^{−4 to} 5 × 10 ⁻¹ mol, relative to 1 mol of the organic silver salt.
The nucleating agent may be added to 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 and dispersion methods include oils such as dibutyl phthalate, tricresyl phosphate, dioctyl sebacate or tri (2-ethylhexyl) phosphate, and an auxiliary solvent such as ethyl acetate and cyclohexanone, and dodecylbenzene. Examples thereof include a method of mechanically preparing an emulsified dispersion by adding a surfactant such as sodium sulfonate, oleoyl-N-methyl taurate, sodium di (2-ethylhexyl) sulfosuccinate. At this time, it is also preferable to add a polymer such as α-methylstyrene oligomer or poly (t-butylacrylamide) for the purpose of adjusting the viscosity and refractive index of the oil droplets.

In addition, as a solid fine particle dispersion method, a nucleating agent powder is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to create a solid dispersion. The method of doing 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 nucleating agent, which is preferably added as 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.

Among the above nucleating agents, it is preferable to use compounds represented by the general formulas (H) and (P), particularly preferably the general formula, in a photosensitive material processed by rapid development with a development time of 20 seconds or less. The compound represented by (H) is preferred.
For light-sensitive materials that require low fogging, it is preferable to use compounds represented by the general formulas (G), (A), (B), and (C), and particularly preferred are those represented by the general formulas (A) and (B). It is a compound represented. Further, it is preferable to use a compound represented by the general formula (C) for a light-sensitive material having little change in photographic performance with respect to environmental conditions when used under various environmental conditions (temperature, humidity).
Specific preferred compounds among the above nucleating agents are listed below, but are not limited to these compounds.

(Other antifoggants)
Examples of other antifoggants include mercury (II) salts described in JP-A No. 11-65021, paragraph number 0113, benzoic acids of paragraph No. 0114, salicylic acid derivatives disclosed in JP-A No. 2000-206642, and formulas described in JP-A No. 2000-221634. A formalin scavenger compound represented by (S), a triazine compound according to claim 9 of JP-A-11-352624, a compound represented by formula (III) of JP-A-6-11791, 4-hydroxy-6-6 And 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 light-sensitive material, but the addition layer is preferably added to the layer having the image forming layer, and more preferably added to the image forming layer. The azolium salt may be added at any step during the preparation of the coating solution, and when added to the image forming layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. Immediately before is preferable. The azolium salt may be added by any method such as powder, solution, fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent. In the present invention, the azolium salt may be added in any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

9) Other additives <1> Mercapto, disulfide, and thiones In the present invention, to suppress or promote development and control development, to improve spectral sensitization efficiency and to improve storage stability before and after development. Can contain a mercapto compound, a disulfide compound, a thione compound, etc., and compounds represented by general formula (I) in paragraph Nos. 0067 to 0069 of JP-A No. 10-62899 and JP-A No. 10-186572 and specific examples thereof Examples thereof are described in paragraph numbers 0033 to 0052 and page 20, lines 36 to 56 of European Patent Publication No. 0803764A1. 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 of European Patent Publication No. 0803764A1, page 23. Lines 48 to 48, described in JP-A No. 2000-356317 and JP-A No. 2000-187298, particularly phthalazinones (phthalazinone, phthalazinone derivatives or metal salts; for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthala Dinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, diphthalic acid) Ammonium, sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride) and Phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6-t-butylphthalazine, 6-chlorophthalazine, 5,7-dimethoxyphthal Razine and 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferred, and a combination of phthalazines and phthalic acids is particularly preferred. Among them, a particularly preferable combination is a combination of 6-isopropylphthalazine and phthalic acid or 4-methylphthalic acid.

<3> Plasticizer and Lubricant In the present invention, known plasticizers and lubricants can be used to improve film physical properties. In particular, it is preferable to use a lubricant such as liquid paraffin, long chain fatty acid, fatty acid amide, fatty acid ester, etc., in order to improve handling at the time of manufacture and scratch resistance at the time of heat development. In particular, liquid paraffin from which low-boiling components have been removed and fatty acid esters having a branched structure and having a molecular weight of 1000 or more are preferred.
Regarding the plasticizer and lubricant that can be used in the image forming layer and the non-photosensitive layer, JP-A No. 11-65021, paragraph No. 0117, JP-A No. 2000-5137, Japanese Patent Application No. 2003-8015, Japanese Patent Application No. 2003-8071, The compounds described in Japanese Patent Application No. 2003-132815 are preferred.

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

<5> Ultra-high contrast agent In order to form a super-high contrast image suitable for printing plate making applications, it is preferable to add a super-high contrast agent to the image forming layer. As for the ultra-high contrast agent and its addition method and addition amount, the formula (H of JP-A No. 11-65021, paragraph No. 0118, JP-A No. 11-223898, paragraph Nos. 0136 to 0193 and JP-A No. 2000-284399 are described. ), Formulas (1) to (3), compounds of formulas (A) and (B), compounds of general formulas (III) to (V) described in Japanese Patent Application No. 11-91652 (specific compounds: 21 to 24) and the high contrast accelerator 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 in an amount of 5 mmol or less, more preferably 1 mmol or less per mol of silver on the side having an image forming layer containing photosensitive silver halide.

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

<6> Preparation and Application of Coating Solution The preparation temperature of the image forming layer coating solution in the invention is preferably 30 ° C. or more and 65 ° C. or less, more preferably 35 ° C. or more and less than 60 ° C., and more preferably 35 ° C. or more and 55 ° C. It is below ℃. 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.

10) Layer structure and other components <1> Surface protective layer The photothermographic material of the invention may be provided with a surface protective layer for the purpose of preventing adhesion of an 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 Japanese Patent Application No. 2000-171936.

  As the binder for the surface protective layer in the present invention, gelatin is preferable, but polyvinyl alcohol (PVA) is preferably used or used in combination. As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), and the like can be used.

  Examples of PVA include those described in paragraph Nos. 0009 to 0020 of JP-A No. 2000-171936. Completely saponified PVA-105, partially saponified PVA-205, PVA-335, and modified polyvinyl alcohol MP- Preferred is 203 (trade name, manufactured by Kuraray Co., Ltd.).

Polyvinyl alcohol coating amount is preferably 0.3 g / m ² or more 4.0 g / m ² or less as (support 1m per ²⁾ of the protective layer (per one layer), 0.3 g / m ² or more 2.0 g / m ² or less is more preferable.

The total coating amount (including water-soluble polymer and latex polymer) of the surface protective layer (per layer) is preferably 0.3 g / m ² or more and 5.0 g / m ² or less as the coating amount (per 1 m ^{2 of the} support). .3g / m ² or more 2.0 g / m ² or less 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 exposure 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 the dye color does not substantially remain 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 0.2-2. The amount of dye used to obtain such an optical density is generally about 0.001 to 1 g / m ² .

  When the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type recording material or a photothermographic material. Similarly, two or more kinds of base precursors may be used in combination.

  In the thermal decoloration using such decoloring dye and base precursor, 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) is 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-63-314535, and JP-A-01-61745. And Japanese Patent Application No. 11-276751. Such a colorant is usually added in a range of 0.1 mg / m ² or more and 1 g / m ² or less, and the layer to be added is preferably a back layer provided on the opposite side of the image forming layer.

<4> Matting Agent In the present invention, it is preferable to add a matting agent to the surface protective layer and the back layer in order to improve transportability. Matting agents are described in JP-A No. 11-65021, paragraph numbers 0126 to 0127.
The matting agent is preferably 1 mg / m ² or more and 400 mg / m ² or less, more preferably 5 mg / m ² or more and 300 mg / m ² or less when expressed in terms of the coating amount per 1 m ² of the photosensitive material.

  Further, the degree of matting of the image forming layer surface may be any as long as so-called stardust failure in which small white spots occur in the image area and light leakage occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, In particular, it is 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 also contained in a layer acting as a so-called protective layer. It is preferable.

<5> Polymer Latex A polymer latex can be added to the surface protective layer and the back layer in the present invention.
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.

  The polymer latex is preferably used in an amount of 10% by weight to 90% by weight, particularly preferably 20% by weight to 80% by weight, based on the total binder (including the water-soluble polymer and latex polymer) in the surface protective layer or the back layer.

<6> pH of membrane surface
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. The method for measuring the film surface pH is described in paragraph No. 0123 of Japanese Patent Application No. 11-87297.

<7> Hardener A hardener may be used for each layer such as an image forming layer, a protective layer, and a back layer.
Examples of hardeners include T.W. H. There are various methods described in “THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION” written by James (published by Macmillan Publishing Co., Inc., published in 1977), pages 77 to 87. Chrome alum, 2,4-dichloro-6-hydroxy -S-triazine sodium salt, N, N-ethylenebis (vinylsulfonacetamide), N, N-propylenebis (vinylsulfonacetamide), polyvalent metal ions described on page 78 of the same, U.S. Pat. No. 4,281, Polyisocyanates such as 060 and JP-A-6-208193, epoxy compounds such as US Pat. No. 4,791,042, and vinyl sulfone compounds such as JP-A 62-89048 are preferably used.

  The hardening agent is added as a solution, and the addition time of this solution into the protective layer coating solution is from 180 minutes before to immediately before application, preferably from 60 minutes to 10 seconds before application. As long as the effects of the present invention are sufficiently exhibited, there is no particular limitation.

  Specific mixing methods include mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid fed to the coater is a desired time, and N.I. Harnby, M.M. F. Edwards, A.D. W. There is a method using a static mixer described in Chapter 8 of Nienow's “Liquid Mixing Technology” (Nikkan Kogyo Shimbun, 1989), translated by Koji Takahashi.

<8> Surfactant The surfactant applicable to the present invention is described in paragraph No. 0132 of JP-A No. 11-65021.
In the present invention, it is preferable to use a fluorochemical surfactant. Preferable 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 present invention, the use of a fluorosurfactant described in Japanese Patent Application No. 2000-206560 is particularly preferred.

<9> Antistatic Agent In the present invention, an antistatic layer containing various known metal oxides or conductive polymers may be provided. The antistatic layer may also serve as the above-described undercoat layer, back layer surface protective layer, or the like, or may be provided separately. Regarding the antistatic layer, paragraph No. 0135 of JP-A No. 11-65021, paragraphs of JP-A Nos. 56-143430, 56-143431, 58-62646, No. 56-120519, and paragraphs of JP-A No. 11-84573. The techniques described in Paragraph Nos. 0078 to 0084 of Nos. 0040 to 0051, US Pat. No. 5,575,957 and JP-A-11-223898 can be applied.

<10> Support The transparent support is heat-treated in a temperature range of 130 ° C. or higher and 185 ° C. or lower in order to relieve internal strain remaining in the film during biaxial stretching and eliminate heat shrinkage strain generated during heat development. Polyester subjected to the above, particularly polyethylene terephthalate is preferably used.

  PEN can be preferably used as a support for a thermosensitive material used in combination with an ultraviolet light emitting screen. However, it is not limited to this. PEN is preferably polyethylene-2,6-naphthalate. The polyethylene-2,6-naphthalate referred to in the present invention is not limited as long as the repeating structural unit is substantially composed of an ethylene-2,6-naphthalenedicarboxylate unit. 6-naphthalene dicarboxylate as well as copolymers in which not more than 10%, preferably not more than 5% of the number of repeating structural units are modified with other components, and mixtures and compositions with other polymers. It is a waste.

  Polyethylene-2,6-naphthalate is synthesized by conjugating naphthalene-2,6-dicarboxylic acid, or a functional derivative thereof, and ethylene glycol or a functional derivative thereof in the presence of a catalyst under suitable reaction conditions. However, one or more appropriate third components (modifiers) are added to the polyethylene-2,6-naphthalate referred to in the present invention before the completion of polymerization of the polyethylene-2,6-naphthalate. Copolymerized or mixed polyester may be used. Suitable third components include compounds having a divalent ester-forming functional group, such as oxalic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, succinic acid, diphenyl ether dicarboxylic acid Dicarboxylic acids such as, lower alkyl esters thereof, oxycarboxylic acids such as p-oxybenzoic acid and p-oxyethoxybenzoic acid, or lower alkyl esters thereof, and dihydric alcohols such as propylene glycol and trimethylene glycol, etc. Compounds. Polyethylene-2,6-naphthalate or a modified polymer thereof is obtained by blocking a terminal hydroxyl group and / or carboxyl group with a monofunctional compound such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol. Alternatively, it may be modified with a very small amount of a trifunctional or tetrafunctional ester-forming compound such as glycerin or pentaerythritol so long as a substantially linear copolymer is obtained.

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.
Specific examples of the support are described in paragraph No. 0134 of JP-A No. 11-65021.

  Examples of the support include water-soluble polyesters disclosed in JP-A-11-84574, styrene-butadiene copolymers described in JP-A-10-186565, and vinylidene chloride described in JP-A-2000-39684 and Japanese Patent Application No. 11-106881, paragraph numbers 0063 to 0080. It is preferable to apply an undercoating technique such as a copolymer.

<11> Other additives The photothermographic material may further contain an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid. A solvent described in paragraph No. 0133 of JP-A No. 11-65021 may be added. Various additives are added to either the image forming 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 coated simultaneously 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. .

The image forming 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 present invention, the viscosity at a shear rate of 0.1 S ⁻¹ of the image forming layer coating solution 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.
Further, at a shear rate of 1000 S ⁻¹ , 1 mPa · s to 200 mPa · s is preferable, and 5 mPa · s to 80 mPa · s is more preferable.

<13> Packaging Material The photothermographic material of the present invention is used to prevent deterioration of photographic performance during storage before use, or to prevent curling or curling in the case of a rolled product form. It is preferable to hermetically package with a packaging material having low oxygen permeability and / or moisture permeability. 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, and even more preferably 1.0 ml / atm / m ² · day. day or less. The moisture permeability is preferably 10 g / atm / m ² · day or less, more preferably 5 g / atm / m ² · day or less, and further preferably 1 g / atm / m ² · day or less. As specific examples of the packaging material having low oxygen permeability and / or moisture permeability, those described in, for example, JP-A-8-254793 and JP-A-2000-206653 can be used.

11) Other technologies that can be used Techniques that can be used in the photothermographic material of the present invention include EP80364A1, EP883022A1, WO98 / 36322, JP-A-56-62648, JP-A-58-62644, JP-A-5-62644. 9-43766, 9-281737, 9-297367, 9-304869, 9-31405, 9-329865, 10-10669, 10-62899, 10-69023 10-186568, 10-90823, 10-171663, 10-186565, 10-186567, 10-186567 to 10-186572, 10-197974, Nos. 10-197982, 10-197983, 10-197985 to 1 No. 0-197987, No. 10-207001, No. 10-207004, No. 10-221807, No. 10-282601, No. 10-288823, No. 10-288824, No. 10-307365, No. 10- No. 312038, No. 10-339934, No. 11-7100, No. 11-15105, No. 11-24200, No. 11-24201, No. 11-30832, No. 11-84574, No. 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, 11-305 84, 11-305380, 11-316435, 11-327076, 11-338096, 11-338098, 11-338099, 11-343420, Japanese Patent Application 2000-187298 , 2000-10229, 2000-47345, 2000-206642, 2000-98530, 2000-98531, 2000-112059, 2000-112060, 2000-112104, Examples thereof include 2000-112064 and 2000-171936.

The construction of a multicolor color photothermographic material may include a combination of these two layers for each color and contains all the components in a single layer as described in US Pat. No. 4,708,928. May be included.
In the case of a multicolor color photothermographic material, each image forming layer is generally a functional or non-functional barrier between each image forming layer as described in US Pat. No. 4,460,681. By using layers, they are kept distinct from each other.

3. 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 an image forming layer 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 0.1 and the point of minimum density (Dmin) + density 0.5 is 0.5 to 0.9, and Prepared so as to have a characteristic curve in which the average gamma (γ) formed by the point of minimum density (Dmin) + density 1.2 and the point of minimum density (Dmin) + density 1.6 is 3.2 to 4.0. It is preferable that 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 techniques of crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material) are 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 phosphors (LaOBr: Tm, LaOCl: Tm, etc.), barium sulfate phosphors [BaSO ₄ : Pb, BaSO 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.), sulfide Physical 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.), was also added various activator as YTaO ₄ and the light emission center to it . 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.

In the fluorescent intensifying screen for X-rays more preferably used in the present invention, 50% or more of emitted light has a wavelength of 350 nm or more and 420 nm or less. In particular, the phosphor is preferably a divalent Eu-activated phosphor, and more preferably a divalent Eu-activated barium halide phosphor. The emission wavelength region is preferably 360 nm to 420 nm, more preferably 370 nm to 420 nm. More preferably, the fluorescent screen has light emission of 70% or more, more preferably 85% or more in the same region.
The ratio of the emitted light is calculated by the following method. That is, the emission spectrum is measured with the emission wavelength on the horizontal axis at equal intervals with a true number and the number of emitted photons on the vertical axis. A value obtained by dividing the area of 350 nm to 420 nm on the chart by the area of the entire emission spectrum is defined as the ratio of light emitted at a wavelength of 350 nm to 420 nm. By having light emission at such a wavelength, high sensitivity can be achieved in combination with the photothermographic material of the present invention.

  In order to have most of the emitted light of the phosphor in such a wavelength range, it is preferable that the half width of the emitted light is narrow. The preferred half-value width is 1 nm to 70 nm, more preferably 5 nm to 50 nm, and still more preferably 10 nm to 40 nm.

  The phosphor to be used is not particularly limited as long as such light emission is obtained. However, in order to achieve high sensitivity, which is the object of the present invention, the phosphor may be an Eu-activated phosphor having a divalent Eu as the emission center. The preferred present invention is not limited to this.

BaFCl: Eu, BaFBr: Eu, BaFI: Eu and those modified in halogen composition, BaSO ₄ : Eu, SrFBr: Eu, SrFCl: Eu, SrFI: Eu, (Sr, Ba) Al ₂ Si ₂ O ₈ : Eu, SrB ₄ O ₇ F: Eu, SrMgP ₂ O ₇ : Eu, Sr ₃ (PO ₄ ) ₂ : Eu, Sr ₂ P ₂ O ₇ : Eu.

A more preferred phosphor is a divalent Eu-activated barium halide phosphor represented by the general formula MX ₁ X ₂ : Eu. Here, M contains Ba as a main component, but it is possible to preferably contain a small amount of other compounds such as Mg, Ca and Sr. X ₁ and X ₂ are halogen atoms, and can be arbitrarily selected from F, Cl, Br, and I. Here, X ₁ is preferably fluorine. X ₂ can be selected from Cl, Br, and I, and mixing some of these halogen compositions can also be used preferably. More preferably, X = Br. Eu is europium. Eu as the emission center is preferably contained at a ratio of 10 ^{−7 to} 0.1 with respect to Ba. More preferably, it is 10 ⁻⁴ or more and 0.05 or less. It is also preferable to mix a small amount of other compounds. Most preferred phosphors include BaFCl: Eu, BaFBr: Eu, and BaFBr _1-X I _X : Eu.

The fluorescent intensifying screen is preferably composed of a support, an undercoat layer on the support, a phosphor layer, and a surface protective layer.
The phosphor layer is prepared by dispersing the phosphor layer in an organic solvent solution containing the phosphor particles and a binder resin, and then dispersing the dispersion into a support (an undercoat layer such as a light reflection layer on the support). Can be formed by directly coating and drying on the subbing layer). Alternatively, after applying this dispersion on a separately prepared temporary support and drying to form a phosphor sheet, the phosphor sheet is peeled off from the temporary support and attached to the support using an adhesive. May be.

  There is no restriction | limiting in particular in the particle size of fluorescent substance particle, Usually, it is the range of about 1 micrometer-15 micrometers, Preferably it is the range of about 2 micrometers-10 micrometers. The volume filling rate of the phosphor particles in the phosphor layer is preferably higher, usually in the range of 60% to 85%, preferably in the range of 65 to 80%, particularly preferably in the range of 68% to 75%. It is a range. (The ratio of the phosphor particles in the phosphor layer is usually 80% by mass or more, preferably 90% by mass or more, and particularly preferably 95% by mass or more.) Binder resin used for forming the phosphor layer, organic Solvents and various additives that can optionally be used are described in various known documents. The thickness of the phosphor layer can be arbitrarily set according to the target sensitivity, but is preferably in the range of 70 μm to 150 μm for the front side screen and in the range of 80 μm to 400 μm for the back side screen. . The X-ray absorption rate of the phosphor layer is determined by the amount of phosphor particles applied.

  The phosphor layer may be a single layer or may be composed of two or more layers. One to three layers are preferable, and one or two layers are more preferable. For example, layers composed of phosphor particles having a relatively narrow particle size distribution and different particle sizes may be laminated. In that case, the layer closer to the support may have a smaller particle size. 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. Further, phosphor layers having different particle diameters may be mixed to form a phosphor layer, or in Japanese Patent Publication No. 55-33560, page 3, left column, line 3 to page 4, left column, line 39. As described, the phosphor layer may have a structure in which the particle size distribution of the phosphor particles is inclined. Usually, the variation coefficient of the particle size distribution of the phosphor is in the range of 30 to 50%, but monodispersed phosphor particles having a variation coefficient of 30% or less can also be preferably used.

Efforts are made to produce a preferable sharpness by dyeing the phosphor layer with respect to the emission wavelength. However, a layer design with as little dyeing as possible is preferably used. The absorption length of the phosphor layer is preferably 100 μm or more, more preferably 1000 μm or more.
The scattering length is preferably designed to be 0.1 μm or more and 100 μm or less. More preferably, it is 1 μm or more and 100 μm or less. The scattering length and the absorption length can be calculated by a calculation formula based on the Kubelka-Munk theory described later.

  As the support, it can be appropriately selected from various supports used for known radiation intensifying screens according to the purpose. For example, a polymer film containing a white pigment such as titanium dioxide or a polymer film containing a black pigment such as carbon black is preferably used. An undercoat layer such as a light reflecting layer containing a light reflecting material may be provided on the surface of the support (the surface on the side where the phosphor layer is provided). A light reflecting layer as described in JP-A-2001-124898 is also preferably used. In particular, the light reflecting layer made of yttrium oxide described in Patent Example 1 and the light reflecting layer described in Patent Example 4 are preferably used. For the preferred light reflecting layer, reference can be made to JP-A-23001-124898, the description of the third term from the 15th line on the right to the fourth term on the right to the 23rd line.

  A surface protective layer is preferably provided on the surface of the phosphor layer. The light scattering length measured at the main emission wavelength of the phosphor is preferably in the range of 5 μm to 80 μm, more preferably in the range of 10 μm to 70 μm, and particularly preferably in the range of 10 μm to 60 μm. Here, the light scattering length represents an average distance in which light travels straight before being scattered once, and the shorter the scattering length, the higher the light scattering property. Further, the light absorption length representing the average free distance until light is absorbed is arbitrary, but from the viewpoint of screen sensitivity, it is preferable that the surface protective layer does not absorb because the desensitization is less. In order to make up for the lack of scattering, it is possible to provide a slight absorption. The absorption length is preferably 800 μm or more, particularly preferably 1200 μm or more. The light scattering length and the light absorption length can be calculated by a calculation formula based on the Kubelka-Munk theory using the measured values measured by the following method.

  First, three or more film samples having the same composition as the surface protective layer to be measured and having different layer thicknesses are prepared. Next, the thickness (μm) and diffuse transmittance (%) of each film sample are measured. The diffuse transmittance can be measured by a device in which an integrating sphere is attached to a normal spectrophotometer. In the measurement in the present invention, a 150φ integrating sphere (150-0901) is attached to a self-recording spectrophotometer (U-3210, manufactured by Hitachi, Ltd.). The measurement wavelength needs to match the peak wavelength of the main light emission of the phosphor of the target phosphor layer to which the surface protective layer is attached. Next, the measured value of the film thickness (μm) and diffuse transmittance (%) are introduced into the following formula (A) derived from Kubelka-Munk's theoretical formula. Formula (A) can be obtained, for example, from “Phosphor Handbook” (edited by Fluorescent Materials Association, Ohm Co., Ltd., published in 1987), page 403, formulas 5 · 12 · 5 · 5 · 15 and diffuse transmittance T ( %) Can be easily derived under boundary conditions.

  Where T is the diffuse transmittance (%), d is the film thickness (μm), and α and β are defined by the following equations, respectively.

  T (diffusion transmittance:%) and d (film thickness: μm) measured for three or more films are respectively introduced into the above equation (A), and K and S satisfying the equation (A) are calculated. The scattering length (μm) is defined by 1 / S and the absorption length (μm) is defined by 1 / K.

  The surface protective layer preferably has a structure in which light scattering particles are dispersed and contained in a resin material. The light refractive index of the light-scattering particles is usually 1.6 or more, preferably 1.9 or more. The particle diameter of the light scattering particles is usually in the range of 0.1 μm to 1.0 μm. Examples of such light-scattering particles include aluminum oxide, magnesium oxide, zinc oxide, zinc sulfide, titanium oxide, niobium oxide, barium sulfate, lead carbonate, silicon oxide, polymethyl methacrylate, styrene, and melamine fine particles. Can be mentioned.

  The resin material used for forming the surface protective layer is not particularly limited, but polyethylene terephthalate, polyethylene naphthalate, polyamide, aramid, fluororesin, polyester, and the like can be preferably used. The surface protective layer is prepared by dispersing the light scattering particles in an organic solvent solution containing a resin material (binder resin), and then preparing the dispersion on the phosphor layer (or any auxiliary material). It can be formed by coating and drying directly (through the layer). Or you may attach the sheet | seat for protective layers formed separately on the fluorescent substance layer using an adhesive agent. The thickness of the surface protective layer is usually in the range of 2 μm to 12 μm, and preferably in the range of 3.5 μm to 10 μm.

  Furthermore, for a preferred method for producing a radiation intensifying screen and materials used therefor, for example, JP-A-9-21899, page 6, left column, line 47 to page 8, left column, line 5, JP-A-6-347598. There are detailed descriptions in the second page, right column, line 17 to page 3, left column, line 33, and the third page, left column, line 42 to page 4, left column, line 22 of the publication. be able to.

  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 Japanese Patent Application No. 2000-320809 is particularly preferable.

(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 about 1 to 10 ° C. at the tip.

  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)
Fuji Medical Dry Imager-FM-DPL and DRYPIX 7000 can be listed as medical laser imagers having an exposure unit and a heat development unit. The system is Fuji Medical Review No. 8, pages 39 to 55, and these techniques can be used. Further, it can be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Film Medical Co., Ltd. as a network system conforming to the DICOM standard.

4). Uses of the Present Invention The silver halide photographic emulsion and photothermographic material of the present invention form a black and white image by a silver image, and are used for medical diagnosis, photothermographic material for industrial photography, photothermographic material for printing. It is preferably used as a photothermographic material for materials and COM.

  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
1. Preparation of PET support and undercoat 1-1. Film formation

  Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured at 25 ° C. in phenol / tetrachloroethane = 6/4 (mass ratio)) was obtained according to a conventional method. This was pelletized and dried at 130 ° C. for 4 hours. The film was colored blue with a blue dye (1,4-bis (2,6-diethylanilinoanthraquinone), then extruded from a T-die and quenched 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 Treatment Both surfaces of the support were treated at room temperature at 20 m / min using a solid state corona treatment machine 6KVA model manufactured by Pillar. 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.

1-3. Preparation of undercoat support 1) Preparation formulation of undercoat layer coating solution (1) (for photosensitive layer side undercoat layer)
46.8 g of Pesresin A520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Bailonal MD1200 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
MP1000 (PMMA polymer fine particles, average particle size 0.4 μm) manufactured by Soken Chemical Co., Ltd.
0.91g
931 ml of distilled water

2) Undercoat After each of the both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm was subjected to the corona discharge treatment, the undercoat coating solution formulation (1) was applied at a wet coating amount of 6.6 ml / m with a wire bar. ² (per one side) was applied and dried at 180 ° C. for 5 minutes, and applied to both sides to prepare an undercoat support.

2. Preparation of coating materials 1) Preparation of photosensitive silver halide emulsion <Photosensitive silver halide emulsion A> (Host emulsion)
4.3 ml of 1% by weight potassium iodide solution is added to 1421 ml of distilled water, 3.5 ml of 0.5 mol / L sulfuric acid, 4.6 g of phthalated gelatin, 5 mass of 2,2 ′-(ethylenedithio) diethanol The solution to which 160 ml of a methanol solution was added was kept in a stainless steel reaction vessel while maintaining the liquid temperature at 75 ° C., and 222.22 g of silver nitrate was added with distilled water and diluted to 218 ml with potassium iodide 36. Solution B in which 6 g was diluted to 366 ml with distilled water was added in a total amount over 16 minutes at a constant flow rate, and solution B was added by the control double jet method while maintaining pAg at 10.2. 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 and diluted to 508.2 ml, and a solution D in which 63.9 g of potassium iodide were diluted to 639 ml with distilled water, and solution C was added at a constant flow rate over 80 minutes. The entire amount was added, and Solution D was added by the control double jet method while maintaining pAg at 10.2. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 11.0.
Thus, an unripe pure silver iodide emulsion (hereinafter referred to as unripe emulsion A) was prepared.

  The obtained silver halide grains had an average projected area diameter of 1.6 μm, an average projected area diameter variation coefficient of 14.4%, an average thickness of 0.082 μm, and an average aspect ratio of 19.5 tabular grains having a total projected area. It accounted for over 80%. The equivalent sphere diameter was 0.68 μm. As a result of analysis by X-ray powder diffraction analysis, 30% or more of silver iodide was present in the γ phase.

<Photosensitive silver halide emulsion B1> (Comparative example)
One mole of the unripe emulsion A was placed in a reaction vessel. The pAg was measured at 40 ° C. and adjusted to 7.3. The 0.5 mol / liter KBr solution and 0.5 mol / liter AgNO ₃ solution were then added at 10 ml / min over 20 minutes by double jet addition. During operation, pAg was maintained at 7.3. Furthermore, 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 8.5.

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, 5.0 × 10 ⁻⁵ mole of sodium benzenethiosulfonate was added to 1 mole of silver in methanol solution, and 5 minutes later, tellurium sensitizer C was added in methanol solution at a rate of 2. The mixture was aged for 91 minutes by adding 0 × 10 ⁻⁵ mol. Thereafter, 1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ and N ″ -diethylmelamine was added, and further 4 minutes later, 5-methyl-2-mercaptobenzimidazole was added to the silver solution with a methanol solution. 3.2 × 10 ⁻³ mol per mol, 5.4 × 10 ⁻³ mol of 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole with 1 mol of silver in a methanol solution and 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added in an aqueous solution to a silver halide emulsion B1 by adding 5.7 × 10 ⁻³ mol to 1 mol of silver.

<Photosensitive silver halide emulsion B2>
(Site director A: polyvinyl alcohol having an average saponification rate of 98% (mass average molecular weight Mw = 22000))
After adjusting pAg to 7.3 at 40 ° C., 2 g of Site Director A solution (polyvinyl alcohol having an average polymerization degree of vinyl acetate of 500 and an average saponification rate of 98% to alcohol (mass average molecular weight Mw = 22000)) in 200 ml of water The silver halide emulsion B2 was added in the same manner as the silver halide emulsion B1, except that a double jet was added 20 minutes later and the tellurium sensitizer C was optimized during chemical sensitization. It was created.

<Photosensitive silver halide emulsion B3>
(Site Director B: Dye B)
After adjusting the pAg to 7.3 at 40 ° C., a Site Director B solution (0.1 g of Dye B dissolved in 100 ml of methanol) is added, 20 minutes later, double jet is added, and chemical sensitization is further performed. A silver halide emulsion B3 was prepared in the same manner as the silver halide emulsion B1, except that the tellurium sensitizer C was optimized.

<Photosensitive silver halide emulsion B4>
(Site Director C: Mercapto Compound C)
After adjusting the pAg to 7.3 at 40 ° C., add a Site Director C solution (0.2 g of Mercapto Compound C dissolved in 100 ml of methanol). A silver halide emulsion B4 was prepared in the same manner as the silver halide emulsion B1, except that the tellurium sensitizer C was optimized.

<Photosensitive silver halide emulsion B5>
(Site director D: pyridinium quaternary salt-containing compound D)
After adjusting the pAg to 7.3 at 40 ° C., a site director D solution (1 g of pyridinium quaternary salt-containing compound D dissolved in 100 ml of water) is added, and 20 minutes later, a double jet is added. A silver halide emulsion B5 was prepared in the same manner as the silver halide emulsion B1 except that the tellurium sensitizer C was optimized during chemical sensitization.

  Table 1 shows the results of measuring the frequency of having an epitaxial junction, the average silver iodide content of the epitaxial junction, and the surface silver iodide content of the photosensitive silver halide emulsions B1 to B5.

<Preparation of mixed emulsion for coating solution>
Each of the above silver halide emulsions B1 to B5 was dissolved, and 7 × 10 ⁻³ mol of benzothiazolium iodide was added per mol of silver in a 1% by mass aqueous solution. Further, the amount of the compound compounds 1, 2 and 3 that can be emitted by one-electron oxidation by one-electron oxidant to emit one or more electrons is 2 × 10 ⁻³ mol per mol of silver halide. Was added.
Further, compounds 1 and 2 having an adsorbing group and a reducing group were added in an amount of 8 × 10 ⁻³ mol per mol of silver halide. Thereafter, water was added so that the silver halide content per liter of the mixed emulsion for coating solution was 15.6 g as silver.

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

<Preparation of fatty acid silver dispersion>
Recrystallized behenic acid 88 kg, distilled water 422 L, 5 mol / L NaOH aqueous solution 49.2 L and t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react to obtain sodium behenate solution B. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient agitation, the total amount of the previous sodium behenate solution and the total amount of silver nitrate aqueous solution were kept at a constant flow rate of 93 minutes and 15 seconds, respectively. And added over 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution is started. After the addition of the aqueous silver nitrate solution, only the sodium behenate solution is added for 14 minutes and 15 seconds. It was made to be. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system for the sodium behenate solution was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution 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 the sodium behenate solution, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.

  When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, average aspect ratio 2.1, and equivalent sphere diameter. The crystal had a coefficient of variation of 11%. (A, b, and c are the text provisions)

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

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

3) Preparation of Reducing Agent-1 Dispersion 10 kg of reducing agent-1 (1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane) and modified polyvinyl alcohol (Kuraray ( 10 kg of water was added to 16 kg of a 10% by weight aqueous solution of Poval MP203), and mixed well to obtain 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.

4) Preparation of nucleating agent dispersion To nucleating agent SH-7 (10 g), 2.5 g of polyvinyl alcohol (Kuraray PVA-217) and 87.5 g of water were added and stirred well, and left as a slurry for 3 hours. did. Thereafter, 240 g of 0.5 mm zirconia beads are put in a vessel together with the slurry, and dispersed for 10 hours with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.) to prepare a solid fine particle dispersion of a nucleating agent. did. As for the particle size, 80% by mass of the particles was 0.1 to 1.0 μm, and the average particle size was 0.5 μm.

5) Preparation of hydrogen bonding compound dispersion 10 kg of 10% by weight aqueous solution of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) 10 kg and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added 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.

6) Preparation of development accelerator dispersion and color adjusting agent dispersion <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 to 10 kg of water 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 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.

<Solid Dispersion of Development Accelerator-2 and Color Toner-1>
The solid dispersions of the development accelerator-2 and the color tone modifier-1 were also dispersed by the same method as the development accelerator-1, and 20% by mass and 15% by mass of a dispersion liquid were obtained, respectively.

7) Preparation of polyhalogen compound dispersion <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 30% 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.

<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 silver iodide complex-forming agent 8 kg of modified polyvinyl alcohol MP203 was dissolved in 174.57 kg of water, then 3.15 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate and 70% by weight of 6-isopropylphthalazine. 14.28 kg of an aqueous solution was added to prepare a 5% by mass solution of a silver iodide complex forming compound.

9) Preparation of mercapto compound (preparation of mercapto compound-1 aqueous solution)
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 SBR latex solution SBR latex was prepared as follows.
In a polymerization kettle of a gas monomer reactor (TAS-2J type manufactured by Pressure Glass Industrial Co., Ltd.), 287 g of distilled water and a surfactant (Pionin A-43-S (manufactured by Takemoto Yushi Co., Ltd.)): solid content 48.5 (Mass%) 7.73 g, 1 mol / liter NaOH 14.06 ml, ethylenediaminetetraacetic acid tetrasodium salt 0.15 g, styrene 255 g, acrylic acid 11.25 g, tert-dodecyl mercaptan 3.0 g were put, the reaction vessel was sealed and the stirring speed was Stir at 200 rpm. After degassing with a vacuum pump and repeating nitrogen gas replacement several times, 108.75 g of 1,3-butadiene was injected 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 stirred for 3 hours. After the reaction was completed, the internal temperature was lowered to room temperature, and then Na ⁺ ion: NH ₄ ⁺ ion = 1: 1 using 1 mol / liter NaOH and NH ₄ OH. Addition treatment was performed so that the molar ratio was 5.3 (molar ratio), and the pH was adjusted to 8.4. Thereafter, the mixture was filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored 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 conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd. was used, and the latex stock solution (44% by mass measured at 25 ° C.) was pH 8.4.

3. Preparation of coating solution 1) Preparation of coating solution for crossover cut layer 17 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 9.6 g of polyacrylamide, 4.2 g of the following ultraviolet light absorber-1, and benzoisothiazolinone 0.03 g, 2.2 g of sodium polyethylene sulfonate, and 844 ml of water were mixed to prepare a crossover cut layer coating solution.
The crossover cut layer was prepared at a flow rate such that the solid content coating amount of the ultraviolet light absorber-1 was 0.04 g / m ² and fed to the coating station.

2) Preparation of Image Forming Layer Coating Liquids 1 to 5 To 1000 g of the fatty acid silver dispersion obtained above and 276 ml of water, an organic polyhalogen compound-1 dispersion, an organic polyhalogen compound-2 dispersion, and an SBR latex (Tg: 17 ° C) liquid, reducing agent-1 dispersion, nucleating agent dispersion, hydrogen bonding compound-1 dispersion, development accelerator-1 dispersion, development accelerator-2 dispersion, color tone modifier-1 dispersion Then, an aqueous solution of mercapto compound-1 and an aqueous solution of mercapto compound-2 were added in turn, a silver iodide complex forming agent was added, and 0.255 mol of silver halide coating solution emulsion was added per mol of fatty acid silver immediately before coating. The mixture was mixed well and fed directly to the coating die.

3) Preparation of intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 64/9/20 / 5/2) 27% 5% by weight 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, water to a total amount of 10000 g Was added with NaOH so that the pH was 7.5 to obtain an intermediate layer coating solution, and the solution was fed to the coating die so as to be 9.1 ml / m ² .
The viscosity of the coating solution was 58 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of surface protective layer first layer coating solution 64 g of inert gelatin was dissolved in water and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 112 g of latex 19.0 wt% solution, 30 ml of 15 wt% methanol solution of phthalic acid, 23 ml of 10 wt% aqueous solution of 4-methylphthalic acid, 28 ml of 0.5 mol / L sulfuric acid, Aerosol OT (American 5 ml of a 5% by weight aqueous solution (made by Cyanamid), 0.5 g of phenoxyethanol, and 0.1 g of benzoisothiazolinone are added to form a coating solution by adding water to a total amount of 750 g. 26 ml of 4% by weight chromium alum consisting of which had been mixed with a static mixer to 18.6ml / m ² to immediately before coating It was fed to a coating die.
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

5) Preparation of surface protective layer second layer coating solution 80 g of inert gelatin was dissolved in water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 64/9/20/5). / 2) 102 g of latex 27.5% by mass solution, 5.4 ml of 2% by mass solution of fluorosurfactant (F-1), and 5% by mass of 2% by mass aqueous solution of fluorosurfactant (F-2). 4 ml, 23 ml of a 5% by mass solution of aerosol OT (manufactured by American Cyanamid), 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm, volume weighted average distribution 30%), polymethyl methacrylate fine particles (average particle) Diameter 3.6 μm, volume weighted average distribution 60%) 21 g, 4-methylphthalic acid 1.6 g, phthalic acid 4.8 g, 0.5 mol / L concentration Water was added to 44 ml of sulfuric acid and 10 mg of benzoisothiazolinone to a total amount of 650 g, and 445 ml of an aqueous solution containing 4% by weight chromium alum and 0.67% by weight phthalic acid was mixed with a static mixer immediately before coating. The resulting solution was used as a surface protective layer coating solution and fed to a coating die so as to be 8.3 ml / m ² .
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4). Preparation of photothermographic materials-1 to 5 Simultaneous application of multiple layers in the order of crossover cut layer, image forming layer, intermediate layer, surface protective layer first layer, surface protective layer second layer from the undercoat surface by the slide bead coating method Thus, a sample of the photothermographic material was prepared. At this time, the image forming layer and the intermediate layer were adjusted to 31 ° C., the first surface protective layer was adjusted to 36 ° C., and the second surface protective layer was adjusted to 37 ° C. The amount of silver applied to the image forming layer was 0.862 g / m ² per side in total for the fatty acid silver and the silver halide. This was applied to both sides of the support.

The total coating amount (g / m ² ) per side of each compound in the image forming layer is as follows.
Fatty acid silver 2.85
Polyhalogen compound-1 0.028
Polyhalogen compound-2 0.094
Silver iodide complex forming agent 0.46
SBR latex 5.20
Reducing agent-1 0.46
Nucleator-1 0.036
Hydrogen bonding compound-1 0.15
Development accelerator-1 0.005
Development accelerator-2 0.035
Color tone adjusting agent-1 0.002
Mercapto Compound-1 0.001
Mercapto compound-2 0.003
Silver halide (as Ag) 0.175

The coating and drying conditions are as follows.
The support was neutralized with ion wind before coating, and coating was performed at a speed of 160 m / min. The coating and drying conditions were adjusted within the following ranges for each sample, and were set to conditions that would provide the most stable surface shape.
The gap between the coating die tip and the support is 0.10 mm to 0.30 mm.
The pressure in the decompression chamber is set to 196 to 882 Pa lower than the atmospheric pressure.
In the subsequent chilling zone, the coating solution is cooled with air at a dry bulb temperature of 10 to 20 ° C.
It is transported in a non-contact manner and dried with a dry air having a dry bulb temperature of 23 ° C. to 45 ° C. and a wet bulb temperature of 15 ° C. to 21 ° C. in a helical contact type non-contact dryer.
After drying, the humidity is adjusted at 25 ° C. and humidity of 40-60% RH. Subsequently, the film surface was heated to 70 ° C. to 90 ° C., and after the heating, the film surface was cooled to 25 ° C.

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

5). Evaluation of Performance 1) Preparation The obtained sample was 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 and heat development The double-sided coated photosensitive material thus prepared was evaluated as follows.
<Exposure>
An X-ray regular screen HI-SCREEN B3 manufactured by FUJIFILM Corporation (CaWO ₄ was used as a phosphor, emission peak wavelength 425 m) was used, and a sample was sandwiched between them to produce an image forming assembly. . This assembly was subjected to X-ray exposure for 0.05 seconds, and X-ray sensitometry was performed. The X-ray apparatus used was a trade name DRX-3724HD manufactured by Toshiba Corporation, and a tungsten target was used. A voltage of 80 kVp was applied to the three phases with a pulse generator, and X-rays passed through a 7 cm water filter having absorption equivalent to that of the human body were used as a light source. The X-ray exposure was changed by the distance method, and step exposure was performed with a width of logE = 0.15.

<Heat development>
The heat development section of the Fuji Medical Dry Laser Imager FM-DPL was modified to produce a heat development machine that can be heated from both sides. In addition, the film was remodeled so that the film sheet could be conveyed by changing the conveyance roller of the heat developing unit to a heat drum. Four panel heaters were set to 112 ° C-118 ° C-120 ° C-120 ° C, and the temperature of the heat drum was set to 120 ° C. Furthermore, the conveyance speed was increased and set to a total of 14 seconds.
After heat development under the above heat development conditions, the resulting image was evaluated with a densitometer.

3) Evaluation item Fog: The optical density of the unexposed area was defined as fog.
Sensitivity: Necessary for obtaining fog + density 0.2, the sensitivity was expressed by the reciprocal of the exposure amount. The sensitivity of Sample-1 is shown as a relative value with 100 as the sensitivity.
Raw storage stability: Each sample was stored in an atmosphere at a relative temperature of 45 ° C. and a relative temperature of 40% for 3 days, and then the same treatment was performed.

4) Results The results obtained are shown in Table 2.
From the results in Table 2, the photothermographic material of the present invention has a sensitivity of about 1.4 to 1.9 times almost without deteriorating the fog, but surprisingly the raw storage stability is improved. In particular, the photothermographic material using the site directors A to C is particularly noted to have improved raw preservation fog.

Example 2
A double-sided photosensitive material was prepared in the same manner as in Example 1.
However, the support was changed to PEN (polyethylene naphthalate). After melting commercially available polyethylene-2,6-naphthalate at 300 ° C., it was extruded from a T-shaped die and subjected to 3.3-fold longitudinal stretching at 140 ° C., followed by 3.3-fold transverse stretching, and further to 250 ° C. And heat-fixed for 6 seconds to obtain a 175 μm film. Corona discharge was performed on the support. The corona discharge treatment uses a solid state corona treatment machine 6KVA model manufactured by Pillar Co., Ltd., and a 30 cm wide support is treated at 20 m / min. At this time, the object to be processed was processed at 0.375 KV · A · min / m ² from the current / voltage readings. The discharge frequency during the treatment was 9.6 KHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm. The undercoating was performed in the same manner as the support of Example 1.

The double-side coated photothermographic material thus obtained was evaluated as follows. The ultra-screen first detail (UV) manufactured by Du Pont was used as a fluorescent screen, and was closely adhered to both sides of the sample of the present invention, given an X-ray exposure of 0.05 seconds, and X-ray sensitometry was performed. . The exposure amount was adjusted by changing the distance between the X-ray tube and the cassette.
After the exposure, heat development was performed in the same manner as in Example 1. As a result, an excellent image was obtained as in Example 1.

Example 3
The temperature at the time of chemical sensitization of the silver halide emulsion B1 of Example 1 was changed to 37 ° C., and the tellurium sensitizer C was replaced with the sulfur sensitizer 1 shown in the specific example to optimize the amount. A silver halide emulsion C1 was prepared in the same manner as the silver halide emulsion B1 except that. The same changes were made for silver halide emulsions B2 to B5 to prepare C2 to C5. Further, double-sided photosensitive materials 31 to 35 were prepared in the same manner as in Example 1, and the same evaluation was performed.

The obtained results are shown in Table 3.
From the results shown in Table 3, the photothermographic material of the present invention has a sensitivity of about 1.6 to 2.2 times with almost no deterioration of the fog, but surprisingly, the raw shelf life was hardly deteriorated. . In particular, the photothermographic material using the site directors A to C is markedly improved in desensitization during raw storage.

Example 4
1. Preparation of photosensitive silver halide emulsion <Sensitive silver halide emulsion D> (Host emulsion)
Add 8.0 ml of 1% by weight potassium iodide solution to 1421 ml of distilled water, and further add 3.5 ml of 0.5 mol / L sulfuric acid, 18.3 g of phthalated gelatin, 5 mass of 2,2 ′-(ethylenedithio) diethanol. The solution to which 160 ml of a methanol solution was added was kept in a stainless steel reaction vessel while maintaining the liquid temperature at 75 ° C., and 222.22 g of silver nitrate was added with distilled water and diluted to 218 ml with potassium iodide 36. Solution B, in which 6 g was diluted to 366 ml with distilled water, was added in a total amount over 16 minutes at a constant flow rate, and solution B was added by the control double jet method while maintaining pAg at 9.6. 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 and diluted to 508.2 ml and a solution D in which 63.9 g of potassium iodide was diluted to 639 ml with distilled water were used. Solution C was added at a constant flow rate over 80 minutes. The whole amount was added, and Solution D was added by the control double jet method while maintaining pAg at 9.6. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 11.0.
Thus, an unripe pure silver iodide emulsion (hereinafter referred to as an unripe emulsion D) was prepared.

  The obtained silver halide grains had an average projected area diameter of 0.79 μm, an average projected area diameter variation coefficient of 12.3%, an average thickness of 0.08 μm, and an average aspect ratio of 9.8 tabular grains having a total projected area. It accounted for over 80%. The equivalent sphere diameter was 0.42 μm. As a result of analysis by X-ray powder diffraction analysis, 50% or more of silver iodide was present in the γ phase.

<Photosensitive silver halide emulsion E1> (Nonuniform low silver iodide content AgBr epi: Comparative example)
One mole of the unripe emulsion D was placed in a reaction vessel. The pAg was 8.9 measured at 40 ° C. The 0.5 mol / liter KBr solution and 0.5 mol / liter AgNO ₃ solution were then added at 10 ml / min over 20 minutes by double jet addition. During operation, pAg was maintained at 10.2. Furthermore, 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 11.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁵ mol was added and aged for 91 minutes. Thereafter, 1.3 ml of a 0.8 mass% methanol solution of N, N′-dihydroxy-N ″ and N ″ -diethylmelamine was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the silver solution with a methanol solution. 4.8 × 10 ⁻³ mole per mole, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution with 5.4 × 10 ⁻³ mole per mole of silver and 1- (3-Methylureidophenyl) -5-mercaptotetrazole was added in an aqueous solution to 8.5 × 10 ⁻³ mol per mol of silver to prepare a silver halide emulsion E1.

<Photosensitive silver halide emulsion E2> (Uniform high silver iodide content AgBr epi: Comparative example)
1 mol of the unripe emulsion D was put in a reaction vessel, adjusted to a pAg of 6.7 at 75 ° C., and maintained at a pAg of 6.7 during the operation, by double jet addition, 0.5 mol / liter. KBr solution and 0.5 mol / liter AgNO ₃ solution were added at 5 ml / min over 40 minutes. Further, a silver halide emulsion E2 was prepared in the same manner as the silver halide emulsion E1, except that the tellurium sensitizer C was optimized during chemical sensitization.

<Photosensitive silver halide emulsion E3>
(Site director A: polyvinyl alcohol having an average saponification rate of 98% (mass average molecular weight Mw = 22000))
After adjusting pAg to 6.7 at 75 ° C., 4 g of Site Director A solution (polyvinyl alcohol having an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol (mass average molecular weight Mw = 22000)) in 400 ml of water In the same manner as the silver halide emulsion E2, except that the tellurium sensitizer C at the time of chemical sensitization is further optimized and the double jet is added. It was created.

<Photosensitive silver halide emulsion E4>
(Site director A: polyvinyl alcohol having an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol (mass average molecular weight Mw = 22000))
1 mol of the unripe emulsion D was put into a reaction vessel, and after adjusting the pAg to 6.7 at 75 ° C., the Site Director A solution (with an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol) Polyvinyl alcohol (4 g of mass average molecular weight Mw = 22000) dissolved in 400 ml of water was added. Twenty minutes later, 0.5 mol / liter KBr solution and 0.5 mol / liter AgNO ₃ solution were added at 5 ml / min for 8 minutes by double jet addition while maintaining the operating pAg at 6.7. After the addition, the temperature was lowered to 40 ° C. Next, the pAg was adjusted to 7.5 at 40 ° C., and 0.5 mol / liter KBr solution and 0.5 mol / liter AgNO ₃ were added by double jet addition while maintaining the pAg at 7.5 during the operation. The solution was added at 10 ml / min over 16 minutes. Further, a silver halide emulsion E4 was prepared in the same manner as the silver halide emulsion E3 except that the tellurium sensitizer C was optimized during chemical sensitization.

<Photosensitive silver halide emulsion E5>
(Site Director B: Dye B)
Halogenation, except that the site director A solution is changed to a site director B solution (0.2 g of dye B dissolved in 200 ml of methanol) and the tellurium sensitizer C is optimized during chemical sensitization. Silver halide emulsion E5 was prepared in the same manner as silver emulsion E4.

<Photosensitive silver halide emulsion E6>
(Site Director C: Mercapto Compound C)
Other than changing the site director A solution to a site director C solution (0.4 g of mercapto compound C dissolved in 200 ml of methanol) and further optimizing tellurium sensitizer C during chemical sensitization. A silver halide emulsion E6 was prepared in the same manner as the silver halide emulsion E4.

<Photosensitive silver halide emulsion E7>
(Site Director E: Sodium Benzenethiosulfonate)
Site director A solution was added to site director E solution (2 g of sodium benzenethiosulfonate dissolved in 200 ml of methanol), 20 minutes later, double jet was added, and tellurium sensitizer for chemical sensitization. A silver halide emulsion E7 was prepared in the same manner as the silver halide emulsion E4 except that C was optimized.

<Photosensitive silver halide emulsion E8>
(Site director A: polyvinyl alcohol having an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol (mass average molecular weight Mw = 22000))
In the silver halide emulsion E4, the 0.5 mol / liter KBr solution used for the double jet addition was changed to a solution containing 0.4 mol KBr and 0.1 mol NaCl per liter, A silver halide emulsion E8 was prepared in the same manner as the silver halide emulsion E4, except that the tellurium sensitizer C was optimized during chemical sensitization.

<Photosensitive silver halide emulsion E9>
(Site director A: polyvinyl alcohol having an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol (mass average molecular weight Mw = 22000))
1500 mL of an aqueous solution containing 4.1 g of KBr and 14.1 g of phthalated gelatin was kept at 40 ° C. and stirred. An aqueous solution containing AgNO ₃ (2.9 g) and KBr (2.0 g) and KI (0.39 g) was added over 40 seconds. After adding an aqueous solution containing 35.5 g of phthalated gelatin, the temperature was raised to 58 ° C. After that, an AgNO ₃ (63.7 g) aqueous solution and a KBr aqueous solution containing KI were added as the first growth while the flow rate was accelerated by the double jet method. The concentration of KI was adjusted so that the silver iodide content was 0.5 mol%. The pAg during operation was maintained at 8.9. In the middle, potassium hexachloroiridate (III) and sodium benzenethiosulfonate were added. Thereafter, an aqueous AgNO ₃ solution (7.4 g) and an aqueous KBr solution containing KI were added over 5 minutes as the outermost layer growth. The concentration of KI was adjusted so that the silver iodide content was 10 mol%. At this time, pAg was maintained at 8.9. Normal washing was carried out, phthalated gelatin was added so that the amount of silver and gelatin contained in 1 kg of emulsion was equal to that of silver halide emulsion A, and adjusted to pH 5.9 and pAg 8.4 at 40 ° C. Further, sensitizing dyes-1, 2, and 3 were added 70% of the saturated adsorption amount immediately before coating.

  The obtained silver halide grains had an average equivalent circle diameter of 0.95 μm, an average equivalent circle diameter variation coefficient of 12.6%, an average thickness of 0.055 μm, an average aspect ratio of 17.2 and tabular grains having a total projected area. It accounted for over 80%. The equivalent sphere diameter was 0.42 μm.

1 mol of this unripe emulsion was put in a reaction vessel, adjusted to a pAg of 7.5 at 40 ° C., and a site director A solution (polyvinyl alcohol having an average degree of polymerization of vinyl acetate of 500 and an average saponification rate of 98% to alcohol). (Mass average molecular weight Mw = 22000) 4 g dissolved in 400 ml of water) was added, and after 20 minutes, 0.5 mol / liter was added by double jet addition while maintaining the pAg during operation at 7.5. KBr solution and 0.5 mol / liter AgNO ₃ solution were added at 10 ml / min over 20 minutes. Further, a silver halide emulsion E9 was prepared in the same manner as the silver halide emulsion E1, except that the tellurium sensitizer C was optimized during chemical sensitization.

  Table 4 shows the results of measuring the frequency of having an epitaxial junction, the average silver iodide content of the epitaxial junction, and the surface silver iodide content of the photosensitive silver halide emulsions E1 to E9.

2. Preparation of coated samples Double-sided photosensitive materials 41 to 49 were prepared in the same manner as in Example 1 using photosensitive silver halide emulsions E1 to E9.

3. Performance Evaluation 1) Exposure Conditions Samples 41 to 48 were exposed in the same manner as in Example 1. Sample 49 was exposed using an X-ray orthoscreen HG-M (using terbium-activated gadolinium oxysulfide as a phosphor, emission peak wavelength 545 nm) manufactured by Fuji Film Co., Ltd.
2) Thermal development and evaluation conditions It carried out similarly to Example 1.
3) Results The results obtained are shown in Table 5.
From the results in the table, the photothermographic material of the present invention has a sensitivity of about 1.4 to 2.5 times almost without deteriorating the fog, but surprisingly the raw storage stability is improved. In particular, the photothermographic materials using the site directors A to C are remarkably improved in fogging deterioration and desensitization during raw storage.

Example 5
1. Preparation of photothermographic material A double-sided photosensitive material was prepared in the same manner as in Example 1 and evaluated as follows.

2. Preparation of fluorescent intensifying screen 1) Preparation of undercoat layer In the same manner as in Example 4 of Japanese Patent Application Laid-Open No. 2001-124898, the film thickness after drying made of alumina powder on a 250 μm polyethylene terephthalate (support) is 50 μm. The light reflecting layer was formed.

2) Production of phosphor sheet BaFBr: Eu phosphor (average particle size 3.5 μm) 250 g, polyurethane binder resin (manufactured by Dainippon Ink and Chemicals, trade name: Pandex T5265M), epoxy binder resin ( Oily Shell Epoxy Co., Ltd., trade name: Epicoat 1001) 2 g, and isocyanate compound (Japan Polyurethane Industry Co., Ltd., trade name: Coronate HX) 0.5 g are added to methyl ethyl ketone and dispersed with a propeller mixer. A 25 PS (25 ° C.) phosphor layer forming coating solution was prepared. This coating solution was applied to the surface of a temporary support (polyethylene terephthalate sheet previously coated with a silicone-based release agent) and dried to form a phosphor layer. The phosphor layer was peeled off from the temporary support to obtain a phosphor sheet.

3) Attaching the phosphor sheet on the light reflecting layer The above phosphor sheet is superimposed on the surface of the light reflecting layer of the support with the light reflecting layer produced in the above step 1), and the pressure is 400 kgw with a calender roll. A pressure was applied under the conditions of / cm ² and a temperature of 80 ° C., and a phosphor layer was provided on the light reflection layer. The thickness of the obtained phosphor layer was 125 μm, and the volume filling factor of the phosphor particles in the phosphor layer was 68%.

4) Formation of surface protective layer A polyester adhesive was applied to one side of polyethylene terephthalate (PET) having a thickness of 6 μm, and a surface protective layer was provided on the phosphor layer by a laminating method. Thus, a fluorescent intensifying screen A comprising a support, a light reflecting layer, a phosphor layer, and a surface protective layer was obtained.

5) Luminescent characteristics The emission spectrum of intensifying screen A measured by X-ray of 40 kVp is shown in FIG. The fluorescent intensifying screen A emitted light with a narrow half-value width having a peak at 390 nm.

3. Performance Evaluation Except that the screen during exposure was changed to the intensifying screen A, the same evaluation as in Example 1 was performed.

Example 6
1. Production of fluorescent intensifying screens In the same manner as the fluorescent intensifying screen A, fluorescent intensifying screens C, D, and E were produced by changing the coating amount of the phosphor coating liquid. Table 6 shows the thickness of the phosphor layer and the volume filling factor of the phosphor of the obtained phosphor intensifying screen.

2. Performance Evaluation Instead of the fluorescent intensifying screen A of Example 5, each sample was subjected to X-ray exposure by a combination of the following screens. Here, the front screen is a screen disposed on the side close to the X-ray source with respect to the photosensitive material, and the back screen is a screen disposed on the side far from the X-ray source.
Similar to Example 5, favorable results were obtained with the sample of the present invention.

It is an emission spectrum of the fluorescent intensifying screen A.

Claims (21)

  A method for producing a photothermographic material having at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support, comprising: (1) the photosensitive halogen A method for producing a photothermographic material, wherein silver halide has a tabular host grain portion and at least one epitaxial junction, and (2) the epitaxial junction is formed in the presence of a site director.   2. The method for producing a photothermographic material according to claim 1, wherein the silver iodide content of the photosensitive silver halide is 40 mol% or more.   3. The method for producing a photothermographic material according to claim 1, wherein the site director is at least one synthetic polymer selected from polyvinyl alcohol and derivatives thereof.   3. The method for producing a photothermographic material according to claim 1, wherein the site director is at least one compound selected from dyes capable of adsorbing to silver halide.   The method for producing a photothermographic material according to claim 1, wherein the site director is at least one compound selected from mercapto compounds.   The method for producing a photothermographic material according to claim 1, wherein an average silver iodide content of the epitaxial junction is 10 mol% or less.   The method for producing a photothermographic material according to claim 1, wherein a surface silver iodide content of the epitaxial junction is 15 mol% or less.   8. The method for producing a photothermographic material according to claim 1, wherein the epitaxial junction is formed through at least two grain formation processes having different temperatures.   The method for producing a photothermographic material according to claim 6, wherein the first particle forming step is 60 ° C. or higher, and the second particle forming step is 50 ° C. or lower.   10. The method for producing a photothermographic material according to claim 8, wherein the first grain forming step is 1 mol% or more and 5 mol% or less of the amount of the host part silver.   11. The method for producing a photothermographic material according to claim 1, wherein a silver bromide content of silver halide in the epitaxial junction is 70 mol% or more.   The method for producing a photothermographic material according to claim 1, wherein chemical sensitization is performed at less than 47 ° C. after the formation of the epitaxial junction.   The method for producing a photothermographic material according to claim 1, wherein the tabular grain has an aspect ratio of 5 or more.   The method for producing a photothermographic material according to claim 1, wherein an average sphere equivalent diameter of the tabular grains is 0.3 μm or more and 5.0 μm or less.   The method for producing a photothermographic material according to claim 1, wherein the tabular grains have an average thickness of 0.3 μm or less.   16. The method for producing a photothermographic material according to claim 1, further comprising a silver iodide complex forming agent.   The method for producing a photothermographic material according to claim 1, wherein the photothermographic material contains a nucleating agent.   A photothermographic material produced by the production method according to claim 1.   19. An image characterized in that the photothermographic material according to claim 18 is subjected to X-ray exposure in close contact with a fluorescent intensifying screen containing a phosphor in which 50% or more of emitted light has a wavelength of 350 nm to 420 nm. Forming method.   The image forming method according to claim 19, wherein the phosphor is a divalent Eu-activated phosphor.   21. The image forming method according to claim 20, wherein the phosphor is a divalent Eu-activated barium halide phosphor.

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