JP2005115121A - Method for preparing silver halide photographic emulsion, silver halide photosensitive material and heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive silver halide emulsion and a photosensitive silver halide material having low fog and high sensitivity and a heat developable photosensitive material excellent in image preservability after development. <P>SOLUTION: In a method for preparing the silver halide emulsion having an average silver iodide content of ≥40 mol%, wherein ≥50% of the total grain projected area includes tabular silver halide grains having an aspect ratio of ≥2, grains are formed in the presence of a silver halide solvent. The silver halide photosensitive material and the heat developable photosensitive material are also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for preparing a silver halide photographic emulsion, a silver halide photosensitive material, and a photothermographic material. In particular, the present invention relates to a method for preparing a silver halide photographic emulsion having an average silver iodide content of 40 mol% or more, a silver halide photosensitive material and a photothermographic material.

(Tabular silver iodide grains)
In the photographic art, the photosensitive silver halide emulsions used usually consist of silver chloride, silver bromide or a silver salt combined with both chloride and bromide ions, each with a small amount of iodide. The added one is used.
Photosensitive silver iodide emulsions are rarely used in the photographic art, but are known in the art. Silver halide emulsions have been reported that use grains containing silver iodide as another distinct phase. A silver phosphate photographic emulsion in which silver is coprecipitated with an iodide and a phosphate has been reported. No separate silver iodide phase has been reported.

The crystal structure of silver iodide has been studied by crystallologists, particularly crystallographers involved in photography, and it is generally known that silver iodide can exist in three different crystal forms (see Non-Patent Document 3). ). The most likely form of silver iodide crystals is a hexagonal wurtzite type called β-phase silver iodide. A face-centered cubic crystal form called γ-phase silver iodide is also stable at room temperature. There is also a body-centered cubic structure called α-phase silver iodide that is stable only at temperatures above about 147 degrees.
Various types of silver iodide grain shapes have been reported, and tabular silver iodide crystals have been observed. As for the preparation method of tabular silver iodide crystals, a preparation method using an excess amount of iodine ions giving a hexagonal crystal structure mainly composed of β-phase silver iodide has been reported.

  For high aspect ratio silver iodide slabs, Maskasky describes a method for preparing silver iodide slabs having a face-centered cubic crystal structure, a thickness of less than 0.3 μm, and an average aspect ratio of 8 or more. (See Patent Documents 1 and 2.) One particularly preferred preparation method is a method in which the pAg of the reaction vessel is maintained within the range of 1.0 to 2.0 during silver iodide precipitation, and the temperature of the reaction vessel is maintained within the range of 30 ° C to 50 ° C. Is described.

(Photothermographic material)
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 a photosensitive material by a laser image setter or laser imager where needed 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. 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 the silver iodide photographic emulsion, in the academic literature, 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, It was known to sensitize. However, the sensitizing effect of these halogen acceptors was very small and extremely insufficient in the photothermographic material targeted by the present invention.

  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 double-side coated X-ray photothermographic material using a blue fluorescent intensifying screen, a photothermographic material using silver iodobromide tabular grains (see, for example, Patent Document 3), or (100). A medical photosensitive material in which tabular grains having a main plane and having a high silver chloride content are coated on both sides of a support is also disclosed in Patent Literature (for example, see Patent Literature 4). The double-side coated photothermographic material is also disclosed in other patent documents. However, in these known examples, when a fine grain silver halide of 0.1 μm or less is used, the haze does not deteriorate, but the sensitivity is low, and it is not practical for photography, while 0.3 μm or more. When the silver halide grains were used, the haze deterioration due to the remaining silver halide and the image quality deterioration due to the deterioration of the printout were severe, and it was not practical.

  Photosensitive materials using tabular grains of silver iodide as silver halide grains are known in the field of wet development, but there are no examples of applications for photothermographic materials. The reason for this is that, as described above, the sensitivity is low, there is no effective sensitizing means, and the technical barrier is further increased in heat development.

In order to use such a photosensitive material for photographing, higher sensitivity is required as a photothermographic material, and the image quality such as haze of an obtained image is further increased.
JP 59-119344 A JP 59-119350 A JP 59-142539 A Japanese Patent Laid-Open No. 10-282606

  An object of the present invention is to improve a silver halide emulsion containing tabular silver halide grains having an average silver iodide content of 40 mol% or more and 50% or more of the total projected area having an aspect ratio of 2 or more. And a silver halide photosensitive material and a photothermographic material containing the same.

The above object of the present invention has been achieved by the following means.
<1> A method for preparing a silver halide emulsion comprising tabular silver halide grains having an average silver iodide content of 40 mol% or more and 50% or more of the total projected area having an aspect ratio of 2 or more, A method for preparing a silver halide emulsion, comprising forming grains in the presence of a silver halide solvent.
<2> The method for preparing a silver halide emulsion according to <1>, wherein the addition amount of the silver halide solvent is increased during grain formation.
<3> The method for preparing a silver halide emulsion according to <1> or <2>, wherein the silver halide solvent is allowed to coexist from the time of nucleation.
<4> The halogen according to any one of <1> to <3>, wherein the silver halide solvent is a compound containing at least one atom selected from a sulfur atom, a selenium atom, and a tellurium atom. Preparation method of silver halide emulsion.
<5> The method for preparing a silver halide emulsion according to any one of <1> to <4>, wherein the silver halide solvent is a compound represented by the general formula (I).

In the general formula (I), L _a1 and L _a3 independently represent an aliphatic group, an aromatic hydrocarbon group, or a heterocyclic ring, and L _a2 represents a divalent aliphatic group or a divalent aromatic group. It represents a hydrocarbon group, a divalent substituted or unsubstituted heterocyclic linking group or a linking group combining them. Aa ₁ and Aa ₂ each independently represent —S—, _—Se— , _—Te— , —O—, —NR _a20 —, —CO—, —SO ₂ —, or a combination thereof. r represents an integer of 0 to 10. Further, L _a1, L _a3 is _{-SO 3 M a1, -PO 3 M} a2 M a3, -NR a1 (R a2), - N + R a3 (R a4) (R a5) · X a1 -, -SO ₂ NR _a6 (R _a7 ), -NR _a8 SO ₂ R _a9 , -CONR _a10 (R _a11 ), -NR _a12 COR _a13 , -SO ₂ R _a14 , -PO (-NR _a15 (R _a16 )) ₂ ,- NR _a17 CONR _a18 (R _a19 ), _{—COOM a4} or a heterocyclic group may be substituted. M _a1 , M _a2 , M _a3 , and M _a4 each independently represent a hydrogen atom or a counter cation. R _{a1 to} R _a20 each independently represent a hydrogen atom, an aliphatic group or an aromatic hydrocarbon group, and X _a1 ⁻ represents a counter anion. However, at least one of A _a1 and A _a2 represents -S- or -Se- or -Te-.

<6> The method for preparing a silver halide emulsion according to any one of <1> to <4>, wherein the silver halide solvent is a compound represented by the general formula (II).

In the general formula (II), X _b and Y _a are independently of each other an aliphatic group, an aromatic hydrocarbon group, a heterocyclic group, —N (R _b1 ) R _b2 , —N (R _b3 ) N (R _b4 ) _Rb5 , _-ORb6 or _-SRb7 is represented. X _b and Y _b may form a ring. Xb and Yb may be substituted with a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, an amino group or an ammonium group, or a hydroxyl group. R _b1 , R _b2 , R _b3 , R _b4 , and R _b5 each independently represent a hydrogen atom, an aliphatic group, an aromatic hydrocarbon group, or a heterocyclic group, and R _b6 and R _b7 are independent from each other. Represents a hydrogen atom, a cation, an aliphatic group, an aromatic hydrocarbon group or a heterocyclic group.

<7> A silver halide light-sensitive material comprising a silver halide prepared by the method for preparing a silver halide emulsion according to any one of <1> to <6>.
<8> A photothermographic material having an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on the same surface of a support, the photosensitive halogenated A photothermographic material, wherein the silver is a photosensitive silver halide prepared by any one of <1> to <6>.
<9> A photosensitive material containing tabular silver halide grains having an average silver iodide content of 40 mol% or more and 50% or more of the total projected area having an aspect ratio of 2 or more, wherein the silver halide A silver halide photosensitive material comprising a silver halide solvent in at least one of a layer containing grains and a layer adjacent thereto.
<10> The silver halide photosensitive material according to <7>, wherein the silver halide solvent is represented by the general formula (I).
<11> The silver halide photosensitive material according to <7>, wherein the silver halide solvent is represented by the general formula (II).
<12> The silver halide photosensitive material according to any one of <9> to <11>, wherein the silver halide photosensitive material is a photothermographic material.

  An object of the present invention is to provide a photosensitive silver halide emulsion and a photosensitive silver halide emulsion having a low fog and a high sensitivity, and a photothermographic material excellent in image storability after development processing.

The present invention is described in detail below.
1. Silver halide emulsion 1) Halogen composition The photosensitive silver halide used in the present invention has a high silver iodide content of 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 such a silver halide having a high silver iodide content, it is possible to design a preferable photosensitive material in which image storability after development processing, in particular, an increase in fog due to light irradiation is remarkably small.

Furthermore, the silver iodide content is preferably 80 mol% or more, more preferably 90 mol% or more, from the viewpoint of image storage stability against light irradiation after processing.
The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure can 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. Further, a technique of localizing silver chloride or silver bromide as an epitaxial portion on the surface of the grain can be preferably used.
The silver iodide of the present invention can have any β phase and γ phase content. 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. Here, the γ phase content is determined using the method proposed by Berry (CR 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) 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.

3) Grain shape The shape of the silver halide grain in the invention is preferably a tabular grain. Specifically, tabular octahedral particles, tabular tetrahedral particles, and tabular icosahedron particles can be given depending on the structure of the side surface. Preferred are tabular octahedral particles and tabular tetrahedral particles. The flat octahedron referred to here is a particle having a {001}, {100}, {010} plane or a particle having a {001}, {120}, {1 (−1) 0} plane, Shaped tetrahedral particles are particles having {001}, {100}, {010}, {101}, {011} or {001}, {120}, {1 (−1) 0}, {121}, Particles having {1 (-1) 1} faces or particles having {001}, {101}, {011}, {10 (-1)}, {01 (-1)} faces or {001}, { 121}, {1 (-1) 1}, {12 (-1)}, {1 (-1) (-1)} faces, and tabular icosahedron grains are {001}, { 100}, {010}, {101}, {011}, {10 (-1)}, particles having {01 (-1)} faces or {0 1}, {120}, {1 (-1) 0}, {121}, {1 (-1) 0}, {12 (-1)}, {1 (-1) (-1)} planes. Particles. Here, a notation such as {001} represents a crystal plane group having a plane index equivalent to the (001) plane. Further, tabular grains having shapes other than those described above are also preferably used.
The aspect ratio of the tabular grains is 2 or more, preferably 5 or more, more preferably 8 or more.
The silver halide having a high silver iodide content composition of the present invention can take a complicated form, but a preferable form is, for example, a grain having rounded corners of a silver halide grain. In this case, there is no particular limitation on the surface index (Miller index) of the outer surface of the photosensitive silver halide grain. The plane index of the main surface constituting the outer surface can be determined by epitaxially bonding a structure having a known crystal orientation, for example, silver bromide grains, to the surface.

4) Grain Forming Methods Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure Jun. 1978, No. 17029, 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.

5) Silver halide solvent The silver halide preparation method of the present invention is characterized in that grains are formed in the presence of a silver halide solvent. This makes it possible to prepare silver halide having a desired grain shape and photographic performance.
A known compound can be used as the silver halide solvent. A preferred silver halide solvent is a compound containing in the molecule at least one atom selected from a sulfur atom, a selenium atom, and a tellurium atom. More preferable silver halide solvents are compounds having structures represented by the following general formulas (I) to (II).

In the general formula (I), L _a1 and L _a3 each independently represent an aliphatic group, an aromatic hydrocarbon group or a heterocyclic ring, and L _a2 represents a divalent aliphatic group or a divalent aromatic group. Represents a hydrocarbon group, a divalent, substituted or unsubstituted heterocyclic linking group or a linking group in combination thereof. Aa1 and Aa2 each independently represent —S—, _—Se— , _—Te— , —O—, —NR _a20 —, —CO—, —SO ₂ —, or a combination thereof. r represents an integer of 0 to 10. Further, L _a1, L _a3 is _{-SO 3 M a1, -PO 3 M} a2 M a3, -NR a1 (R a2), - N + R a3 (R a4) (R a5) · X a1 -, -SO ₂ NR _a6 (R _a7 ), -NR _a8 SO ₂ R _a9 , -CONR _a10 (R _a11 ), -NR _a12 COR _a13 , -SO ₂ R _a14 , -PO (-NR _a15 (R _a16 )) ₂ ,- NR _a17 CONR _a18 (R _a19 ), _{—COOM a4} or a heterocyclic group may be substituted. M _a1 , M _a2 , M _a3 and M _a4 may be the same or different and each represents a hydrogen atom or a counter cation. R _{a1 to} R _a20 each independently represent a hydrogen atom, an aliphatic group or an aromatic hydrocarbon group, and X _a1 ⁻ represents a counter anion. However, at least one of A _a1 and A _a2 represents -S- or -Se- or -Te-.

In the general formula (II), X _b and Y _a are an aliphatic group, an aromatic hydrocarbon group, a heterocyclic group, —N (R _b1 ) R _b2 , —N (R _b3 ) N (R _b4 ) R _b5 , _-ORb6 or _-SRb7 is represented. X _b and Y _b may form a ring. Xb and Yb may be substituted with a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, an amino group or an ammonium group, or a hydroxyl group. Rb1, Rb2, Rb3, Rb4 and Rb5 represent a hydrogen atom, an aliphatic group, an aromatic hydrocarbon group or a heterocyclic group, and Rb6 and Rb7 represent a hydrogen atom, a cation, an aliphatic group, an aromatic hydrocarbon group or Represents a heterocyclic group.

  The addition amount of the silver halide solvent is preferably from 0.01 mol to 20 mol per mol of silver halide. More preferably, 0.01 mol to 10 mol per mol of silver halide, and still more preferably 0.02 mol to 5 mol per mol of silver halide are added.

As a method of adding a silver halide solvent, a method of adding a silver halide solvent into a reaction vessel before starting addition of silver ions and halide ions, or a certain amount of silver ions and halogen in the reaction vessel. After adding halide ion, add silver halide solvent and then add silver ion and halide ion, or add silver halide solvent while adding silver ion and halide ion in reaction vessel The method is preferably used. A silver ion solution or a silver halide solution or a method in which a silver halide solvent is mixed and added to both the silver ion solution and the silver halide solution is also preferably used.
Specific examples of the silver halide solvent including the compounds of the general formula (I) and the general formula (II) in the present invention are shown below, but the present invention is not limited thereto.

6) Gelatin As the gelatin contained in the light-sensitive silver halide emulsion used in the present invention, various gelatins can be used. In order to prepare tabular grains, the molecular weight is 10,000 to 200. 1,000 gelatin is preferably used. These gelatins may be used at the time of grain formation or dispersion after desalting, but are preferably used at the time of grain formation in order to prepare tabular grains. In addition, amino group-modified gelatin can be used. For example, phthalated gelatin, trimellitated gelatin, and succinylated gelatin can be used.

7) Heavy metal The photosensitive silver halide grain of the present invention may contain a metal or metal complex of Group 8 to Group 10 of the Periodic Table (showing Groups 1 to 18). As the central metal of the group 8 to group 10 metal or metal complex of the periodic table, rhodium, ruthenium and iridium are preferable. One kind of these metal complexes may be used, or two or more kinds of complexes of the same metal and different metals may be used in combination. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻³ mol with respect to 1 mol of silver. These heavy metals and metal complexes and methods for adding them are described in JP-A-7-225449, JP-A-11-65021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240. In the present invention, silver halide grains in which a hexacyano metal complex is present on the outermost surface of the grains are preferred. The hexacyano metal complexes include [Fe (CN) ₆ ] ⁴⁻ , [Fe (CN) ₆ ] ³⁻ , [Ru (CN) ₆ ] ⁴⁻ , [Os (CN) ₆ ] ⁴⁻ , [Co ( CN) ₆ ] ³⁻ , [Rh (CN) ₆ ] ³⁻ , [Ir (CN) ₆ ] ³⁻ , [Cr (CN) ₆ ] ³⁻ , [Re (CN) ₆ ] ^{3− and the} like. . In the present invention, a hexacyano Fe complex is preferred.
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 may be non-chemically sensitized, but chemically sensitized by at least one of a chalcogen sensitization method, a gold sensitization method, and a reduction sensitization method. Is preferred. 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, dimolforin disulfide, cystine, lenthionine (1,2,3,5,6-pentathiepane)), polythionates, elemental sulfur and active gelatin Well as It is possible to have. 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, JP-A-4-109340, JP-A-4-271341, and JP-A-5-40324. No. 5-11385, Japanese Patent Application No. Hei 4-202415, No. 4-330495, No. 4-333030, No. 5-4203, No. 5-4204, No. 5-106977, No. 5-236538. Selenium compounds described in JP-A-5-241642 and JP-A-5-286916 can be used.

  Specifically, colloidal metal selenium, selenoureas (eg, N, N-dimethylselenourea, trifluoromethylcarbonyl-trimethylselenourea, acetyl-trimethylselenourea), selenoamides (eg, selenoamide, N, N-diethyl) Phenylselenoamide), phosphine selenides (eg, triphenylphosphine selenide, pentafluorophenyl-triphenylphosphine selenide), selenophosphates (eg, tri-p-tolylselenophosphate, tri-n) -Butylselenophosphate), selenoketones (for example, selenobenzophenone), isoselenocyanates, selenocarboxylic acids, selenoesters, diacyl selenides 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.

  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. A compound can be used.

  Specifically, phosphine tellurides (for example, butyl-diisopropylphosphine telluride, tributylphosphine telluride, tributoxyphosphine telluride, ethoxydiphenylphosphine 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 and the like may be used. In particular, diacyl (di) tellurides and phosphine tellurides are preferable. Particularly, compounds described in literatures described in paragraph No. 0030 of JP-A-11-65021, general formula (II) in JP-A-5-313284, Compounds represented by (III) and (IV) are more preferred.

  Particularly, in the chalcogen sensitization of 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 5252455, Belgian Patent No. 691857 and the like 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 I can do it.

  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 to 10 ⁻¹ mol, preferably 10 ⁻⁷ to 10 mol, per mol of silver halide. ^Use about ^-2 mol.
Similarly, although the addition amount of the gold sensitizer used in the present invention varies depending on various conditions, as a guideline, it is 10 ⁻⁷ mol to 10 ⁻² mol, more preferably 10 ⁻⁶ mol to 5 mol per mol of silver halide. × 10 ^-3 mol. 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 is 3 to 10, preferably 4 to 9, temperature is 20 to 95 ° C., preferably about 25 to 80 ° C. is there.

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 more or pAg at 4 or less, and reduction sensitization is performed 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 to 10 ⁻¹ mol per mol of silver halide, more preferably 10 ⁻⁶ mol to 5 × 10 ^−2. mol.

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

The one-electron oxidant produced by one-electron oxidation contained in the 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 to 36), JP2001-500996 (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" described in patents such as European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051 Compound called Azukazo sensitizers "it can be mentioned. The preferred ranges of these compounds are the same as the preferred ranges described in the cited patent specifications.

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

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

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

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

  Of the compounds of types 1 and 2, “a compound having an adsorptive group to silver halide in the molecule” or “a compound having a partial structure of a spectral sensitizing dye in the molecule” is preferable. Typical examples of the adsorptive group to silver halide include 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 5-mercaptotetrazole group, 3-mercapto-1,2,4-triazole group, and benzotriazole group, most preferred are 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. Preferable examples of the adsorptive group having two or more mercapto groups as a partial structure (such as a dimercapto-substituted nitrogen-containing terocyclic 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 (such as a trialkyl phosphonio group, dialkylaryl (or heteroaryl) phosphonio group, alkyldiaryl (or heteroaryl) phosphonio group, triaryl (or heteroaryl) phosphonio group). Is mentioned. More preferably, a quaternary salt structure of nitrogen is used, and more preferably a 5-membered or 6-membered nitrogen-containing aromatic heterocyclic group containing a quaternized nitrogen atom is used. Particularly preferably, a pyridinio group, a quinolinio group, or an isoquinolinio group is used. These nitrogen-containing heterocyclic groups containing a quaternized nitrogen atom may have an arbitrary substituent.

Examples of 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 the 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 type 1 or 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.

  The type 1 and type 2 compounds in the present invention may be used at any time during the preparation of the photosensitive silver halide emulsion and during the process of producing the photothermographic material. For example, at the time of photosensitive silver halide grain formation, desalting step, chemical sensitization, before coating. Moreover, it can also add in several steps in these processes. The addition position is preferably from the end of formation of the photosensitive silver halide grains to before the desalting step, at the time of chemical sensitization (immediately after the start of chemical sensitization to immediately after completion), and before coating, more preferably from the time of chemical sensitization Until before mixing with the non-photosensitive organic silver salt.

  The compounds of type 1 and type 2 in the present invention are preferably added after being dissolved in water, a water-soluble solvent such as methanol or ethanol, or a mixed solvent thereof. When the compound is dissolved in water, the compound having higher solubility when the pH is increased or decreased may be dissolved at a higher or lower pH and added.

The compounds of type 1 and type 2 in the present invention are preferably used in an emulsion layer containing a photosensitive silver halide and a non-photosensitive organic silver salt, but the photosensitive silver halide and the non-photosensitive organic silver salt are used. It may be added to the protective layer and the intermediate layer together with the emulsion layer to be contained and diffused during coating. The timing of addition of the compound of the present invention is preferably before or after the sensitizing dye, and is preferably 1 × 10 ^{−9 to} 5 × 10 ⁻¹ mol, more preferably 1 × 10 ^{−8 to} 5 per mol of silver halide. X10 ^-2 mol in a silver halide emulsion layer.

  Specific examples of type 1 and type 2 compounds in the present invention are given below, but the present invention is not limited to these.

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 capable of being 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. Represents. ]

  In formula (I), the adsorptive group represented by A is a group that directly adsorbs to silver halide or a group that promotes adsorption to silver halide. 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 the adsorptive 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 an 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 having a heterocyclic ring, or a “—S—” group, a “—Se—” group, a “—Te—” group, or a “═N—” group that can coordinate to a silver ion through a coordination bond A heterocyclic group having a partial structure of benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group, purine group and the like as thiophene group as the latter example , Thiazole group, oxazole group, benzothiophene group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, tri Jin group, seleno azole 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 “—S—S—”.
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 groups having —NH— groups that can form imino silver (> NAg) as a heterocyclic partial structure (for example, benzotria) Lumpur 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, Aminophenols, sulfonamidophenols, and hydroquinones, catechols, resorcinols, benzenetriols, polyphenols such as bisphenols), acylhydrazines, carbamoylhydrazines, 3-pyrazolidones, etc. The residue after removing one And the like. Of course, these may have an arbitrary substituent.

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

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

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

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

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

  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 adsorptive group and a reducing group of the present invention. .

  The compound in the present invention can be easily synthesized by a known method.

  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 desalting process start, 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 in the emulsion layer, it may be added to the adjacent protective layer or intermediate layer together with the 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 to 1 mol, preferably 1 × 10 ^{−5 to} 5 ×, per 1 mol of photosensitive silver halide. 10 ⁻¹ mol, more preferably 1 × 10 ⁻⁴ to 1 × 10 ⁻¹ mol.

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

11) Sensitizing dye The sensitizing dye that can be applied to the present invention can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and is suitable for spectral characteristics of the exposure light source. Sensitizing dyes with sensitivity can be advantageously selected. The photothermographic material of 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. 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 Application No. 0803764A1, page 19, line 38 to page 20, line 35, 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.

The addition amount of the sensitizing dye in the present invention can be set to a desired amount in accordance with sensitivity and fogging performance, but is preferably 10 ⁻⁶ to 1 mol, more preferably 1 mol per mol of silver halide in the photosensitive layer. Is 10 ⁻⁴ to 10 ⁻¹ mol.

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

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

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

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

2. Photothermographic material The photothermographic material of the present invention has an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support. ing. Preferably, a surface protective layer may be provided on the image forming layer, or a back layer or a back protective layer may be provided on the opposite surface.
The configuration of each layer and preferred components thereof will be described in detail.

2-1. 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 effectively applied after heat development compared to before heat development. It is preferred to contain a compound that decreases.
As the compound that effectively reduces the visible light absorption derived from the photosensitive silver halide after heat development, it is particularly preferable to use a silver iodide complex-forming agent.

(Silver iodide complex forming agent)
The silver iodide complex-forming agent in the present invention 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 an electron to a silver ion as a coordination atom (electron donor: Lewis base). Is possible. The stability of the complex is defined by the sequential stability constant or the total stability constant, but depends on the combination of the three 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 preferred are 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 (substitution position is not limited), 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 Or an aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl) , Or heterocycle) 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, Norinio 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-sulfonylsulfuric 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 ring of the present invention is a cation (e.g., pyridinium, triazolium Etc.) to form an inner salt.

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 the general formula (2), R ²¹ and R ²² represent 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 represents 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 to} R ⁶³ each independently represents 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 silver iodide complex-forming powder in the present invention is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave. And a method of preparing 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%-300 mol%.

2-2. Organic silver salt The non-photosensitive organic silver salt used in the present invention is relatively stable to light, but is heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide and a reducing agent. In this case, the silver salt forms a silver image. 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 of the present invention can be used in a desired amount, preferably 0.1g / m ² ~5g / m ² as silver amount, more preferably from ^{1g / m 2 ~3g / m 2} . Particularly preferably ^{1.2g / m 2 ~2.5g / m 2} .

2-3. 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 a 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 capable of substituting for 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, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, a cyclohexyl group. Group, 1-methylcyclohexyl group, benzyl group, methoxymethyl group, methoxyethyl group and the like. More preferred are methyl group, ethyl group, propyl group, isopropyl group and t-butyl group.

X ¹ and X ¹ ′ are preferably a hydrogen atom, a halogen atom, or an alkyl group, 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 and 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 the general formula (R) of the present invention are shown below, but the present invention is not limited thereto.

  Particularly preferred are compounds as shown in (R-1) to (R-20).

The addition amount of the reducing agent is preferably a ^{0.01g / m 2 ~5.0g / m 2} , more preferably from ^{0.1g / m 2 ~3.0g / m 2} , the image forming 5 mol% to 50 mol% is preferably contained with respect to 1 mol of silver on the surface having the layer, and more preferably 10 mol% to 40 mol%.

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

  The reducing agent of 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.

  The solid fine particle dispersion method includes a method in which a reducing agent is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to create a solid dispersion. Can 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 preferable is a solid particle dispersion method of a reducing agent, and it is preferable to add fine particles having an average particle size of 0.01 μm to 10 μm, preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 1 μm. In the present application, it is preferable to use other solid dispersions dispersed in a particle size within this range.

2-4. Development accelerator In the photothermographic material of the present invention, a sulfonamide phenol compound represented by the general formula (A) described in JP-A No. 2000-267222, JP-A No. 2000-330234, or the like is used as a development accelerator. Hindered phenol compounds represented by the general formula (II) described in JP-A-2001-92075, general formula (I) described in JP-A-10-62895, JP-A-11-15116, and the like; A hydrazine-based compound represented by the general formula (1) described in No. 074278 and a phenol-based or naphthol-based compound represented by the general formula (2) described in Japanese Patent Application No. 2000-76240 are preferably used. . These development accelerators are used in the range of 0.1 mol% to 20 mol% with respect to the reducing agent, preferably in the range of 0.5 mol% to 10 mol%, more preferably 1 mol% to 5 mol. % Range. The introduction method to the light-sensitive material includes the same method as the reducing agent, but it is particularly preferable to add as a solid dispersion or an emulsion dispersion. When added as an emulsified dispersion, it is added as an emulsified dispersion dispersed using a high-boiling solvent and a low-boiling auxiliary solvent that are solid at room temperature, or as a so-called oilless emulsified dispersion that does not use a high-boiling solvent. It is preferable to add.

  In the present invention, among the above development accelerators, hydrazine compounds represented by the general formula (1) described in Japanese Patent Application No. 2001-074278 and the general formula (2) described in Japanese Patent Application No. 2000-76240. A phenolic or naphtholic compound represented by the formula is particularly preferred.

  Hereinafter, although the preferable specific example of the development accelerator of this invention is given, this invention is not limited to these.

2-5. Hydrogen bonding compound In the present invention, the reducing agent has an aromatic hydroxyl group (—OH), or, in the case of having an amino group, a non-reducing compound having a group capable of forming a hydrogen bond with the amino group. It is preferable to do.

  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).

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 effect of the present invention, at least one of R ²¹ to R ²³ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. In addition, it is preferable that R ²¹ to R ²³ are the same group in that they can be obtained at low cost.

  Specific examples of the hydrogen bonding compound including the compound of the general formula (D) in the present invention are shown below, but the present invention is not limited thereto.

  Specific examples of the hydrogen bonding compound include those described in Japanese Patent Application Nos. 2000-192191 and 2000-19481 in addition to those described above.

  The hydrogen bonding compound of 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. The compound of the present invention forms a complex by a hydrogen bond with a compound having a phenolic hydroxyl group in a solution state. Depending on the combination of the reducing agent and the compound of the general formula (A) of the present invention, the compound of the present invention Can be separated.

  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 of the present invention are mixed as a powder and complexed at the time of dispersion with a sand grinder mill or the like using an appropriate dispersant can be preferably used.

  The hydrogen bonding compound of the present invention is preferably used in the range of 1 mol% to 200 mol%, more preferably in the range of 10 mol% to 150 mol%, still more preferably 30 mol%, based on the reducing agent. It is in the range of ˜100 mol%.

2-6. Binder The binder of the organic silver salt-containing layer of the present invention may be any polymer, suitable binders are transparent or translucent and generally colorless, natural resins and polymers and copolymers, synthetic resins and polymers and copolymers, etc. Film-forming media such as gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) ), Poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers Poly (vinyl acetal) s (e.g. poly (Vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) ), Poly (olefin) s, cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

  In the present invention, the glass transition temperature of the binder of the layer containing the organic silver salt is preferably 10 ° C. or higher and 80 ° C. or lower, more preferably 20 ° C. to 70 ° C., and 23 ° C. or higher and 65 ° C. or lower. More preferably.

In this specification, Tg is 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 weight 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.
As the transition temperature value (Tgi) of the homopolymer glass of each monomer, the value of Polymer Handbook (3rd Edition) (by J. Brandrup, EH Immergut (Wiley-Interscience, 1989)) was adopted.

  The polymer used as the binder may be used alone or in combination of two or more 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 kinds of polymers having different Tg are blended and used, the weight average Tg is preferably within the above range.

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

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

The “equilibrium moisture content at 25 ° C. and 60% RH” is the following using the weight W1 of the polymer in the humidity-controlled equilibrium under the atmosphere of 25 ° C. and 60% RH and the weight W0 of the polymer in the 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 moisture content at 25 ° C. and 60% RH of the binder polymer of the present invention is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass. % To 1% by mass is desirable.

  The binder of the present invention is particularly preferably a polymer that can be dispersed in an aqueous solvent. Examples of the dispersed state include latex in which fine particles of water-insoluble hydrophobic polymer are dispersed and polymer molecules dispersed in a molecular state or forming micelles, and all are preferable. The average particle size of the dispersed particles is preferably 1 to 50000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  In the present invention, preferred embodiments of the polymer that can be dispersed in an aqueous solvent include acrylic polymers, poly (esters), rubbers (eg, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (acetic acid). Hydrophobic polymers such as vinyl), poly (vinylidene chloride) and poly (olefin) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer.

  These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. When the molecular weight is too small, the mechanical strength of the image forming layer is insufficient, and when the molecular weight is too large, the film formability is poor, which is not preferable.

  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.

Latex of P-1; -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000, Tg 61 ° C.)
Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg 59 ° C.)
P-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
Latex of P-4; -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C.)
Latex of P-5; -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C.)
Latex of P-6; -St (70) -Bu (27) -IA (3)-(crosslinkability)
Latex of P-7; -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C.)
P-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
Latex (crosslinkability) of P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-
P-10; latex of VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80000)
P-11; latex of VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
Latex of P-12; -Et (90) -MAA (10)-(molecular weight 12000)
P-13; Latex of -St (70) -2EHA (27) -AA (3) (molecular weight 130000, Tg 43 ° C)
P-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33,000, Tg 47 ° C.)
Latex of P-15; -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg 23 ° C.)
Latex of P-16; -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)

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

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

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

  As the polymer latex used in the present invention, a styrene-butadiene copolymer latex is particularly preferable. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably 40:60 to 95: 5. The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99% by mass. The preferred molecular weight range is the same as described above.

  Examples of latexes of styrene-butadiene copolymer that are preferably used in the present invention include the aforementioned P-3 to P-8, 14, and 15, commercially available products LACSTAR-3307B and 7132C, Nipol Lx416, and the like.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose may be added to the organic silver salt-containing layer of the light-sensitive material of the present invention.

  The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder of the organic silver salt-containing layer.

  The organic silver salt-containing layer (that is, the image forming layer) of the present invention is preferably formed using a polymer latex as a binder. The amount of the binder in the organic silver salt-containing layer is preferably such that the weight ratio of total binder / organic silver salt is 1/10 to 10/1, more preferably 1/5 to 4/1.

  Further, such an organic silver salt-containing layer is usually a photosensitive layer (image forming layer) containing a photosensitive silver halide that is a photosensitive silver salt. The weight ratio of silver halide is preferably 400-5, more preferably 200-10.

The total amount of binder in the image forming layer of the present ^{invention, 0.2g / m 2 ~30g / m} 2, more preferably from 1g / m ² ~15g / m ² is preferred. 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.

  In the present invention, the solvent of the organic silver salt-containing layer coating solution of the light-sensitive material (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent) is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent is more preferably 50% by mass or more, and still more preferably 70% by mass or more.

  Specific examples of the preferred solvent composition include water 100, 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%).

2-7. Antifoggant 1) Organic polyhalogen compound The present invention preferably contains a compound represented by the following general formula (H) as an antifoggant.

General formula (H) Q- (Y) n-C (Z ₁ ) (Z ₂ ) X

  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 ₂ —, —SO ₂ —, —C (═O) N (R) —, —SO ₂ N (R) —, and 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.

  Although the specific example of the compound of general formula (H) of this invention is shown below, this invention is not limited to these.

The compound represented by the general formula (H) of the present invention is preferably used in the range of 10 ^{−4 to} 0.8 mol, more preferably 10 ⁻³ per mol of the non-photosensitive silver salt of the image forming layer. It is preferable to use in the range of ˜0.1 mol, more preferably in the range of 5 × 10 ^{−3 to} 0.05 mol.
In particular, when the silver halide having a high silver iodide content of the present invention is used, it is used in the range of 5 × 10 ^{−3 to} 0.03 mol in order to obtain a sufficient antifogging effect. Most preferred.

  In the present invention, examples of the method for incorporating the compound represented by the general formula (H) into the photosensitive material include the methods described in the method for containing a reducing agent.

  The melting point of the compound represented by the general formula (H) is preferably 200 ° C. or lower, more preferably 170 ° C. or lower.

  Other organic polyhalides used in the present invention include those disclosed in the patents described in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021. In particular, an organic halogen compound represented by the formula (P) of Japanese Patent Application No. 11-87297, an organic polyhalogen compound represented by the general formula (II) of Japanese Patent Application Laid-Open No. 10-339934, and Japanese Patent Application No. 11-205330 The organic polyhalogen compounds described are preferred.

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

  Antifoggant, stabilizer and stabilizer precursor that can be used in the present invention described in paragraph No. 0070 of JP-A-10-62899, page 20, line 57 to page 21, line 7 of European Patent No. 0803764A1 Patented compounds and compounds described in JP-A Nos. 9-281737 and 9-329864 can be mentioned.

  The photothermographic material in the invention may contain an azolium salt for the purpose of fog prevention. Examples of the azolium salt include compounds represented by general formula (XI) described in JP-A-59-193447, compounds described in JP-B-55-12581, and general formula (II) described in JP-A-60-153039. And the compounds represented. The azolium salt may be added to any part of the photosensitive material, but the addition layer is preferably added to the layer having the photosensitive layer, and more preferably to the organic silver salt-containing layer.

  The azolium salt may be added at any step in the coating solution preparation. When added to the organic silver salt-containing layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used. To immediately before coating. The azolium salt may be added by any method such as powder, solution, fine particle dispersion. Moreover, you may add as a solution mixed with other additives, such as a sensitizing dye, a reducing agent, and a color toning agent.

In the present invention, the azolium salt may be added in any amount, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

2-8. Other Additives 1) Mercapto, disulfide, and thiones In the present invention, mercapto is used to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. A compound, a disulfide compound, and a thione compound can be contained. Paragraph Nos. 0067 to 0069 of JP-A No. 10-62899, a compound represented by formula (I) of JP-A No. 10-186572, and specific examples thereof include a paragraph Nos. 0033 to 0052, European Patent Publication No. 0803764A1, page 20, lines 36 to 56, Japanese Patent Application No. 11-273670, and the like. Of these, mercapto-substituted heteroaromatic compounds are preferred.

2) Toning agent In the photothermographic material of the invention, it is preferable to add a toning agent. For the toning agent, paragraphs 0054 to 0055 of JP-A No. 10-62899, p. Lines 21, 23 to 48, JP-A No. 2000-356317 and Japanese Patent Application No. 2000-187298, in particular, phthalazinones (phthalazinone, phthalazinone derivatives or metal salts; for example, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone and 2,3-dihydro-1,4-phthalazinedione); phthalazinones and phthalic acids (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, A combination of diammonium phthalate, sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride); phthalazines (phthalazine, phthalazine derivatives or metal salts; for example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 6 -T-butylphthalazine, 6-chloro (Talazine, 5.7-dimethoxyphthalazine, and 2,3-dihydrophthalazine) are preferable. In particular, in the combination with silver halide having a high silver iodide content, the combination of phthalazine and phthalic acid is preferable.

  The amount of phthalazine added is preferably 0.01 to 0.3 mol, more preferably 0.02 to 0.2 mol, particularly preferably 0.02 to 0.1 mol, per mol of the organic silver salt. It is. This addition amount is an important factor for promoting development, which is a problem in the silver halide emulsion having a high silver iodide content of the present invention. By selecting an appropriate addition amount, both sufficient developability and low fog are achieved. Is possible.

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

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

5) Nucleator In the present invention, it is preferable to add a nucleator to the image forming layer. Regarding the nucleating 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 Japanese Patent Application No. 11-87297 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 nucleation promoter are described in paragraph No. 0102 of JP-A No. 11-65021 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

In order to use formic acid or formate as a strong fogging substance, it is preferably contained at 5 mmol or less, more preferably 1 mmol or less, per mol of silver on the side having the image forming layer containing photosensitive silver halide.
When a nucleating agent is used in the photothermographic material of the invention, it is preferable to use an acid formed by hydrating diphosphorus pentoxide or a salt thereof in combination. Acids or salts thereof formed by hydration of diphosphorus pentoxide include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametalin An acid (salt) etc. can be mentioned. Examples of the acid or salt thereof formed by hydrating diphosphorus pentoxide particularly preferably include orthophosphoric acid (salt) and hexametaphosphoric acid (salt). Specific examples of the salt include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, ammonium hexametaphosphate and the like.
The amount of 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. ˜500 mg / m ² is preferable, and 0.5 mg / m ^{2 to} 100 mg / m ² is more preferable.

2-9. Preparation and Application of Coating Solution The preparation temperature of the image forming layer coating solution of the present 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. or less. . Further, the temperature of the image forming layer coating solution immediately after the addition of the polymer latex is 30.
It is preferable that the temperature is maintained at a temperature of not lower than 65 ° C and not higher than 65 ° C.

2-10. Layer structure, other components

  The photothermographic material of the present invention can have a non-photosensitive layer in addition to the image forming layer. The non-photosensitive layer includes (a) a surface protective layer provided on the image forming layer (on the side farther than the support), (b) between the plurality of image forming layers and between the image forming layer and the protective layer. It can be classified into an intermediate layer provided therebetween, (c) an undercoat layer provided between the image forming layer and the support, and (d) a back layer provided on the opposite side of the image forming layer.

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

1) Surface protective layer The photothermographic material according to the invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer or a plurality of layers. The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and Japanese Patent Application No. 2000-171936.

  As the binder for the surface protective layer of the present invention, gelatin is preferable, but it is also preferable to use polyvinyl alcohol (PVA) or a combination thereof. As gelatin, inert gelatin (for example, Nitta gelatin 750), phthalated gelatin (for example, Nitta gelatin 801), and the like can be used.

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

Preferably 0.3g / m ² ~4.0g / m ² as a polyvinyl alcohol coating amount (per support 1 m ²⁾ of the protective layer (per one ^{layer), 0.3g / m 2 ~2.0g /} m 2 Is more preferable.

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

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

  When the dye is decolored in this way, the optical density after heat development can be reduced to 0.1 or less. Two or more kinds of decoloring dyes may be used in combination in a heat decoloring type 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 nm to 450 nm can be added for the purpose of improving the silver 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 the range of 0.1 mg / m ^{2 to 1} g / m ² , and the back layer provided on the opposite side of the photosensitive layer is preferable as the layer to be added.

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.
When the matting agent is indicated by the coating amount per the photosensitive material 1 m ^2, preferably from ^{1mg / m 2 ~400mg / m 2} , more preferably ^{5mg / m 2 ~300mg / m 2} .

  Further, the mat degree of the image forming layer surface may be any as long as a so-called stardust failure in which small white spots occur in the image portion and light leakage occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, Particularly, 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 is 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 or the back layer of 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 mass to 90% by mass, particularly preferably 20% by mass to 80% by mass, based on the total binder (including the water-soluble polymer and latex polymer) of the surface protective layer or the back layer.

6) Membrane pH
The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before heat development. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2.

For the adjustment of the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, and a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or heat development.
In addition, it is also preferable to use ammonia in combination with a nonvolatile base such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. 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 the photosensitive layer, protective layer, and back layer of the present invention.
Examples of hardeners include T.W. H. There are various methods described in "THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTH EDITION" written by James (published by Macmillan Publishing Co., Inc., published in 1977), pages 77 to 87. -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 Surfactants applicable to the present invention are 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 was subjected to a heat treatment in a temperature range of 130 to 185 ° C. in order to relieve internal strain remaining in the film during biaxial stretching and to eliminate heat shrinkage strain generated during heat development processing. Polyester, particularly polyethylene terephthalate is preferably used.

  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 combining 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, methoxypolyalkylene glycol, etc. 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 An antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid may be further added to the photothermographic material. A solvent described in paragraph No. 0133 of JP-A No. 11-65021 may be added. Various additives are added to either the photosensitive layer or the non-photosensitive layer. With respect to these, WO 98/36322, EP 803764A1, JP-A-10-186567, 10-18568 and the like can be referred to.

12) Coating method The photothermographic material in the invention may be coated by any method. Specifically, various coating operations including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. And Stephen F. Kistler, Peter M. et al. Extrusion coating or slide coating described in pages 399 to 536 of “LIQUID FILM COATING” (CHAPMAN & HALL, 1997) by Schweizer is preferably used, and slide coating is particularly preferably used.

  An example of the shape of a slide coater used for slide coating is shown in FIG. 11b. 1 If desired, two or more layers can be simultaneously coated by the method described on pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent No. 837,095. .

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

13) Packaging material The photothermographic material of the present invention is to prevent photographic performance from deteriorating during storage before use, or to prevent curling or curling in the case of a rolled product. 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.

14) Other usable techniques The 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.

15) Color imaging The composition of a multicolor photothermographic material may include a combination of these two layers for each color, and within a single layer as described in US Pat. No. 4,708,928. May contain all the components.
In the case of a multicolor color photothermographic material, each emulsion layer is generally a functional or non-functional barrier layer between each photosensitive layer as described in U.S. Pat. No. 4,460,681. Are used to keep them distinguished from each other.

3. Image forming method 3-1. Exposure The photothermographic material of the present invention may be a “single-sided type” having an image forming layer only on one side of a support, or a double-sided type having image forming layers on both sides.
(Double-sided photothermographic material)
The photothermographic material of the present invention can be preferably used in an image forming method for recording an X-ray image using an X-ray intensifying screen.
The process of forming an image using these photothermographic materials comprises the following processes.
(A) a step of obtaining an image forming assembly by installing the photothermographic material between a pair of X-ray intensifying screens;
(B) placing a subject between the assembly and the X-ray source;
(C) irradiating the subject with X-rays having an energy level in the range of 25 kVp to 125 kVp;
(D) removing the photothermographic material from the assembly;
(E) A step of heating the photothermographic material taken out at a temperature in the range of 90 ° C to 180 ° C.

  The photothermographic material used in the assembly of the present invention is an image obtained by performing stair exposure with X-rays, and the image obtained by heat development on orthogonal coordinates having the same optical axis (D) and exposure amount (log E) coordinate axis unit length. 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 to have a characteristic curve having an average gamma (γ) of 3.2 to 4.0 formed by a point of minimum density (Dmin) + density 1.2 and minimum density (Dmin) + density 1.6. 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 technique of crossover cut (double-sided photosensitive material) and antihalation (single-sided photosensitive material) is described in JP-A-2-68539, page 13, lower left column, line 1 to page 14, lower left column, line 9; Dyes or dyes and mordants can be used.

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

In the present invention, preferred phosphors include those shown below. Tungstate phosphors (CaWO ₄ , MgWO ₄ , CaWO ₄ : Pb, etc.), terbium activated rare earth oxysulfide phosphors [Y ₂ O ₂ S: Tb, Gd ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, (Y, Gd) O ₂ S: Tb, Tm, etc.], terbium-activated rare earth phosphate phosphors (YPO ₄ : Tb, GdPO ₄ : Tb, LaPO ₄ : Tb, etc.), terbium activated rare earth oxyhalide phosphors (LaOBr: Tb, LaOBr: Tb, Tm, LaOCl: Tb, LaOCl: Tb, Tm, LaOBr: Tb, GdOBr: Tb, GdOCl: Tb, etc.) , Thulium activated rare earth oxyhalide 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.

  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.

3-2. Thermal 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 90 ° C to 180 ° C, more preferably 100 ° C to 140 ° C.
The development time is preferably 1 second to 60 seconds, more preferably 5 seconds to 30 seconds, and particularly preferably 5 seconds to 20 seconds.

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

  Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and rapidly develop the photothermographic material. It is also possible to suppress changes in the shape of the support of the photothermographic material due to heating of the photothermographic material.

3-3. System Fuji Medical Dry Imager-FM-DPL can be mentioned as a medical laser imager provided with an exposure unit and a thermal development unit. The system is Fuji Medical Review No. 8, pages 39 to 55, and these techniques can be used. Further, it can also be applied as a photothermographic material for a laser imager in “AD network” proposed by Fuji Medical Co., Ltd. as a network system conforming to the DICOM standard.

4). Use of the present invention The photothermographic material using the high silver iodide photographic emulsion of the present invention forms a black-and-white image by a silver image and is used for medical diagnosis, photothermographic material for industrial photography, and printing. It is preferably used as a photothermographic material or a photothermographic material for 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 photosensitive silver halide emulsion (Preparation of silver halide emulsion 1)
8 ml of 10% by weight potassium iodide solution was added to 1421 ml of distilled water, 12 ml of 1 mol / L sodium hydroxide solution, 36.5 g of phthalated gelatin, and 5% by weight methanol of 2,2 ′-(ethylenedithio) diethanol. The solution to which 25 ml of the solution was added was kept at 75 ° C. while stirring in a stainless steel reaction vessel, and distilled water was diluted to 218 ml by adding distilled water to 22.22 g of silver nitrate and 36.6 g of potassium iodide in distilled water. Solution B diluted to 366 ml with a total amount of Solution A was added over 32 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 160 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 20 minutes after the start of the addition of Solution C and Solution D to 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after completion of the addition of the solution C, a total amount of 3 × 10 ⁻⁴ mol of iron (II) hexacyanide aqueous solution per 1 mol of silver was added. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and the precipitation / desalting / water washing steps were performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare silver halide emulsion 1 having a pAg of 11.0.

  The silver halide grains of the silver halide emulsion 1 are pure silver iodide, the average projected area diameter is 0.72 μm, the variation coefficient of the average projected area diameter is 17.7%, the average thickness is 0.060 μm, and the average aspect ratio is 12. Zero tabular grains accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.36 μm. As a result of analysis by X-ray powder diffraction analysis, 30% or more of silver iodide was present in the γ phase.

(Preparation of silver halide emulsions 2-3)
Prepare silver halide emulsions 2-3 in the same manner as silver halide emulsion 1, except that the addition amount of 2,2 '-(ethylenedithio) diethanol in a 5% by weight methanol solution is 100 ml and 400 ml. did.

(Preparation of silver halide emulsions 4 to 6)
8 ml of 10% by weight potassium iodide solution was added to 1421 ml of distilled water, and 12 ml of 1 mol / L sodium hydroxide solution, 36.5 g of phthalated gelatin, and 100 ml of 3.57% by weight methanol solution of AF-162 were added. While stirring the solution in a stainless steel reaction vessel at 45 ° C., the solution A was diluted to 218 ml by adding distilled water to 22.22 g of silver nitrate and 36.6 g of potassium iodide was diluted to 366 ml with distilled water. The total amount of the solution B was added at a constant flow rate over 32 minutes, and the solution B was added by the control double jet method while maintaining the 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 160 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 20 minutes after the start of the addition of Solution C and Solution D to 1 × 10 ⁻⁴ mol per mol of silver. Further, 5 seconds after the completion of the addition of the solution C, a total amount of 3 × 10 ⁻⁴ mol of potassium iron (II) hexacyanide was added per 1 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 silver halide emulsion 4 having a pAg of 11.0.
In the same manner as silver halide emulsion 4, except that the addition amount of 1,3-dimethyl-imidazolidine-2-thione 3.57% by mass methanol solution is 100 ml and 400 ml. Emulsions 5-6 were prepared.

(Preparation of silver halide emulsion 7-9)
8 ml of 10% by weight potassium iodide solution was added to 1421 ml of distilled water, 12 ml of 1 mol / L sodium hydroxide solution, 36.5 g of phthalated gelatin, and 5% by weight methanol of 2,2 ′-(ethylenedithio) diethanol. The solution to which 25 ml of the solution was added was kept at 75 ° C. while stirring in a stainless steel reaction vessel, and distilled water was diluted to 218 ml by adding distilled water to 22.22 g of silver nitrate and 36.6 g of potassium iodide in distilled water. The solution A was diluted to 366 ml with 50 ml of a 5 mass% methanol solution of 2,2 ′-(ethylenedithio) diethanol, and the solution A was added at a constant flow rate over 32 minutes. The pAg 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, solution C diluted with 51.86 g of silver nitrate to 508.2 ml and diluted with potassium iodide 63.9 g were diluted to 639 ml with distilled water, and 5 mass of 2,2 ′-(ethylenedithio) diethanol. Solution D to which 88 ml of% methanol solution was added was added in a total amount over 160 minutes at a constant flow rate, 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 20 minutes after the start of the addition of Solution C and Solution D to 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, a total amount of 3 × 10 ⁻⁴ moles of iron (II) hexacyanide aqueous solution per mole of silver was added. 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 silver halide emulsion 4 having a pAg of 11.0.
In the same manner as silver halide emulsion 7, except that the amount of 2,2 ′-(ethylenedithio) diethanol 5% by weight methanol solution added to solutions B and D was adjusted to 100 ml and 176 ml. Silver halide emulsion 8 was prepared.
Similarly to silver halide emulsion 7, except that the amount of 5% by weight methanol solution of 2,2 ′-(ethylenedithio) diethanol added to solutions B and D was adjusted to 200 ml and 352 ml. Silver emulsion 9 was prepared.

(Preparation of silver halide emulsions 10-12)
8 ml of 10% by weight potassium iodide solution was added to 1421 ml of distilled water, 12 ml of 1 mol / L sodium hydroxide solution, 36.5 g of phthalated gelatin, 3.57 of 1,3-dimethylimidazolidine-2-thione. The solution added with 25 ml of a mass% methanol solution was kept at 45 ° C. while stirring in a stainless steel reaction vessel, and the solution A diluted with 218 ml of distilled water added to 22.22 g of silver nitrate and potassium iodide 36 0.6 g was diluted to 366 ml with distilled water, and solution B to which 50 ml of a 3.57 mass% methanol solution of 1,3-dimethyl-imidazolidine-2-thione was added was added to solution A at a constant flow rate for 32 minutes. The solution B was added by the control double jet method while maintaining the 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, Distilled Water was added to 51.86 g of Silver Nitrate to dilute Solution C diluted to 508.2 ml and 63.9 g of Potassium Iodide to 639 ml with Distilled Water, and 1,3-dimethyl-imidazolidine-2-thione Solution D to which 88 ml of 3.57 mass% methanol solution was added was added in a total amount over 160 minutes at a constant flow rate, 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 20 minutes after the start of the addition of Solution C and Solution D to 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, a total amount of 3 × 10 ⁻⁴ moles of iron (II) hexacyanide aqueous solution per mole of silver was added. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and the precipitation / desalting / water washing steps were performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide emulsion 10 having a pAg of 11.0.
Similarly to silver halide emulsion 10, except that the amounts of 3.57 mass% methanol solution of 1,3-dimethyl-imidazolidine-2-thione added to solutions B and D were adjusted to 100 ml and 176 ml. Thus, a silver halide emulsion 11 was prepared.
In addition, silver halide emulsion 12 was prepared in the same manner as silver halide emulsion 10, except that the 3.57 mass% methanol solution of AF-162 added to solutions B and D was made 200 ml and 352 ml.

(Preparation of silver halide emulsion 13-comparative example-)
A silver halide emulsion 13 was prepared in the same manner as silver halide emulsion 1, except that a 5% by weight methanol solution of 2,2 ′-(ethylenedithio) diethanol was not added.

(Evaluation of silver halide emulsions 1 to 13)
The shape of the silver halide emulsion prepared above is summarized in Table 1.
As can be easily recognized by examining the data shown in Table 1, the silver iodide solvent is allowed to coexist in the formation of high silver iodide grains, thereby increasing the sphere equivalent diameter of the silver iodide grains and increasing the shape. It becomes possible to prepare a flat plate having an aspect ratio. It has also been found that tabular grains having a higher aspect ratio can be prepared by adding a silver halide solvent during grain formation.

Example 2
(Preparation of silver halide emulsions 14 to 19)
1 mol of the silver halide emulsion 2 of Example 1 was put into a reaction vessel, and by adding double jet, 0.5 mol / L potassium bromide solution and 0.5 mol / L silver nitrate solution were added at 10 ml / min. Over 10 minutes, substantially 10 mol% silver bromide was epitaxially precipitated onto the silver iodide host emulsion. During operation, pAg was maintained at 10.2. Furthermore, pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and precipitation / desalting / water washing steps were 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. After 20 minutes of temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol with respect to 1 mol of silver, and further 5 minutes later, tellurium sensitizer C was added to the methanol solution in an amount of 2.9 × with respect to 1 mol of silver. 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 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to methanol. 4.8 × 10 ⁻³ mol per mol of silver in solution, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in a methanol solution to 5.4 × 10 5 per mol of silver ^-3 mol and 1- (3-methylureidophenyl) -5-mercaptotetrazole were added in an aqueous solution to 8.5 × 10 ^-3 mol per mol of silver to prepare a silver halide emulsion 14.

  The silver halide grains of the obtained silver halide dispersion are high silver iodide grains containing 10 mol% of silver bromide, the average projected area diameter is 0.86 μm, and the variation coefficient of the average projected area diameter is 17.7. %, An average thickness of 0.045 μm, and an average aspect ratio of 19.1 accounted for 80% or more of the total projected area. The equivalent sphere diameter was 0.37 μm. As a result of analysis by X-ray powder diffraction analysis, 30% or more of silver iodide was present in the γ phase.

In the same manner as the silver halide emulsion 14, except that the silver halide emulsion contained in the reaction vessel is replaced with the silver halide emulsion 5, 8, 11, 13 instead of the silver halide emulsion 2. Emulsions 15, 16, 17, and 18 were prepared.
The silver halide grains of the obtained silver halide dispersion were tabular grains and grains having an epitaxial junction structure at the corners.

Example 3
1. 1. Preparation of coated sample 1-1. Undercoat of support Biaxially stretched 175 μm-thick blue dyed (containing 1,4-bis (2,6-diethylanilinoanthraquinone) polyethylene terephthalate support was subjected to corona discharge, and the following main components Each coating solution containing was applied to both sides of the support by a wire bar coater in the order of the first undercoat layer and the second undercoat layer.

・ First undercoat layer (support side)
The amount of the coating solution per 1 m ² on one side of the support was 4.9 ml. The amount of each additive material applied per 1 m ² on one side of the support is as follows.
・ Styrene-butadiene copolymer latex (as solid content) 0.31 g
・ 2,4-Dichloro-6-hydroxy-s-triazine sodium 8mg
Drying temperature 190 ° C

-Second undercoat layer The amount of the coating solution per 1 m ² on one side of the support was 7.9 ml. The amount of each additive material applied per 1 m ² on one side of the support is as follows.
・ Gelatin 80mg
_{· C 12 H 25 O (CH} 2 CH 2 O) 10 H 1.8mg
・ Preservative D 0.27mg
・ Polymethylmethacrylate 2.5mg matting agent 2.5mg
Drying temperature 185 ° C

1-2. Application of photographic layer On the undercoat-coated support described above, it was simultaneously coated on both sides by a simultaneous extrusion method so as to form a crossover cut layer, a silver halide emulsion layer, and a surface protective layer from the support side, and dried.

1) Crossover cut layer

(Method for preparing dye for crossover cut)
The dye A (solid 10 g) was stirred for 2 hours in a mixed solvent of 150 ml of methanol and 50 ml of water while controlling at 70 ° C. to prepare a wet cake dye. The obtained dye crystals contained 1 mol of methanol and 2 mol of water with respect to 1 mol of the dye. The composition of the crystal solvent was determined by drying the wet cake at room temperature for measurement, confirming methanol by ¹ H-NMR, and confirming crystal water by Karl Fischer titration. It was also confirmed that when this crystal was heated at 150 ° C., methanol and water of crystallization were released. The dye solid concentration in the wet cake was 50% by mass.

(Method for preparing microcrystalline aqueous dispersion of dye for crossover cut)
The wet cake dye described above was not dried, and 3.0 g was weighed as a dye solid as it was. After mixing 1.2 g of a 25% by mass solution of Demol SNB (manufactured by Kao Co., Ltd.) as water and a dispersant for dispersion in advance, the above dye is added, and water is added so that the total becomes 30 g. After adjustment, the mixture was mixed well to obtain a slurry. 120 g of zirconia beads were prepared, put into a vessel together with the slurry, and dispersed in a 1/16 gallon sand grinder mill (manufactured by Imex Co., Ltd.) at a rotational speed of 1500 rpm while cooling with water. Zirconia beads having an average particle diameter of 1 mm were used, and the dispersion time was 8 hours. After the completion of dispersion, water was added so that the solid content concentration of the dye was 5% by mass, and the dispersion was taken out. This dye dispersion was designated as DP1.

(Method for preparing crossover cut layer coating solution)
Each compound was added so that it might become the following coating amounts. The amount of material applied per 1 m ^{2 on} one side was listed in the order of addition of each compound.
・ Gelatin 0.47g
・ DP1 (Dye dispersion for crossover cut, as dye solids)
8.4mg
-Sodium polystyrene sulfonate (average molecular weight 600,000)
10mg
・ A-1 5mg
・ Preservative D 1mg

At this time, the pH of the coating solution was adjusted to 6.0 using a small amount of acetic acid or sodium hydroxide. The application amount was 12.4 ml per 1 m ² on one side.

2) Silver halide emulsion layer Each material was added to the emulsion so that the coating amount was as follows. The amount of material applied per 1 m ^{2 on} one side is shown.
・ Amount of coated silver 1.8g
・ Gelatin 1.7g
Dextran (average molecular weight 39,000) 428mg
・ Polystyrene sulfonate sodium (average molecular weight 600,000) 40mg
・ A-2 204mg
・ A-3 2.2mg
・ A-4 0.5mg
・ A-5 2.8mg
・ 1,2-Bis (vinylsulfonylacetamido) ethane 50mg
At this time, the coating amount of this silver halide emulsion layer was 45.2 ml per 1 m ² on one side.

3) Surface protective layer coating solution Each compound was added so that it might become the following coating amounts.
Amount of material applied per 1 m ^{2 on} one side • Gelatin 0.767 g
-Sodium polyacrylate (average molecular weight 400,000) 80mg
-Sodium polystyrene sulfonate (average molecular weight 600,000) 1.1mg
Matting agent-1 (average particle size 3.7 μm) 70 mg as solid content
・ A-6 18.1mg
・ A-7 34.5mg
・ A-8 6.8mg
・ A-9 3.2mg
・ A-10 1.4mg
・ A-11 2.1mg
・ A-12 1.0mg
・ Preservative D 0.9mg
・ P-benzoquinone 0.7mg

At this time, the pH of the coating solution for the surface protective layer was adjusted to 6.8 using a small amount of sodium hydroxide. The coating amount was 10.7 ml per 1 m ² on one side. The compounds in the above were as follows.

2. Evaluation of performance 1) Exposure and development The double-sided coated photosensitive material thus prepared was evaluated as follows.
An X-ray regular screen HI-SCREEN B3 (using CaWO ₄ as the phosphor, emission peak wavelength: 425 m) made by FUJIFILM Co., Ltd. is used, and a sample is sandwiched between them to create an image forming assembly. did. 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. After the exposure, development processing was performed under the following wet processing conditions.

  The film was processed for 5 minutes with an automatic developing processor CEPROS-M2 manufactured by Fuji Photo Film Co., Ltd. and a processing solution CE-D1.

2) Evaluation items (sensitivity, cover density evaluation)
The density of the obtained image was measured with a densitometer, and a density characteristic curve with respect to the logarithm of the exposure amount was created. The optical density of the unexposed part was defined as the fog density (Dmin). In addition, the reciprocal of the exposure amount at which an optical density of 1.5 was obtained was defined as sensitivity, and the sensitivity of the coating material 1 was defined as 100, and expressed as a relative value. The smaller the numerical value, the better the fog, and the higher the numerical value, the better the performance.
(Evaluation of image preservation (printout))
The obtained image was stored under a fluorescent lamp with an illuminance of 1000 Lux for 24 hours, and then an increase in fog density (ΔDmin part) of the fog part was evaluated. The smaller the value, the better the image storability (printout property).

3) Evaluation results The results are shown in Table 2.
As can be easily recognized by examining the data shown in Table 2, the tabular grains of the present invention are excellent in high sensitivity, low fog and image stability during storage after processing.

Example 4
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 (weight ratio)) was obtained according to a conventional method. This was pelletized and dried at 130μ 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 Discharge Treatment Using a solid state corona discharge treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

1-3. Preparation of undercoat support 1) Preparation of undercoat layer coating solution Takamatsu Yushi Co., Ltd. Pes Resin A-520 (30% by mass solution) 46.8 g
Bailonal MD-1200 10.4g manufactured by Toyobo Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 1% by mass solution 11.0 g
MP-1000 manufactured by Soken Chemical Co., Ltd. (PMMA polymer fine particles, average particle size 0.4 μm)
0.91g
931 ml of distilled water

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

2. Preparation of coating material 1) Preparation of mixed emulsions 14 to 18 for coating solution Each of the silver halide emulsions 14 to 18 prepared in Example 2 was dissolved, and benzothiazolium iodide was silvered in a 1% by mass aqueous solution. 7 × 10 ⁻³ mol was added per mol. 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, the compounds 1, 2 and 3 having an adsorbing group and a reducing group were added in an amount of 8 × 10 ⁻³ mol per mol of silver halide.
Further, 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. It was a crystal with a variation coefficient of 11% (a, b, and c are defined in the text).

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

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

3) Preparation of reducing agent dispersion << Preparation of reducing agent-1 dispersion >>
10 kg of water is added to 16 kg of a 10 mass% aqueous solution of reducing agent-1 (2,2′-methylenebis- (4-ethyl-6-tert-butylphenol)) and 10% by weight of a modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Add and mix well to make a slurry. This slurry was fed with a diaphragm pump, dispersed for 3 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
<< Preparation of Reducing Agent-2 Dispersion >>
10 masses of reducing agent-2 (6,6′-di-t-butyl-4,4′-dimethyl-2,2′-butylidenediphenol) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour, and then further heated at 80 ° C. for 1 hour to obtain a reducing agent-2 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.50 μm and a maximum particle diameter of 1.6 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of hydrogen bonding compound dispersion << Preparation of hydrogen bonding compound-1 dispersion >>
Add 10 kg of water to 10 kg of 10% aqueous solution of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Mix to make 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. The dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

5) Preparation of development accelerator dispersion and color tone modifier dispersion << Preparation of development accelerator-1 dispersion >>
10 kg of development accelerator-1 and 20 kg of 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added 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.

  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.

6) Preparation of polyhalogen compound dispersion << Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (tribromomethanesulfonylbenzene), 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 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.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of an organic polyhalogen compound-2 (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by weight 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.

7) Preparation of silver iodide complex forming agent 8 kg of modified polyvinyl alcohol MP203 was dissolved in 174.57 kg of water, and 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.

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

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

9) 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 7.73 g, 1 mol / l 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, and the reaction vessel sealed The mixture was stirred at a stirring speed of 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 liquid 1) Preparation of image forming layer coating liquids 14 to 18 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, SBR latex (Tg: 17 ° C.) liquid, reducing agent-1 dispersion, reducing agent-2 dispersion, hydrogen bonding compound-1 dispersion, development accelerator-1 dispersion, development accelerator-2 dispersion, color tone The modifier-1 dispersion, the mercapto compound-1 aqueous solution, and the mercapto compound-2 aqueous solution were added sequentially, and after adding the silver iodide complex forming agent, the mixed emulsions 14-18 for silver halide coating solution were added immediately before coating. 0.22 mol per 1 mol of fatty acid silver was added in the amount of silver, mixed well, sent as it was to the coating die, and applied.

2) 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 (copolymerization weight ratio 64/9/20 / 5/2) 27% 5% aqueous solution of aerosol OT (American Cyanamid Co., Ltd.) in 4200 ml of 19% latex liquid, 135 ml of 20% aqueous solution of diammonium phthalate, water to a total amount of 10,000 g Was adjusted with NaOH to a pH of 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).

3) 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 weight 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).

4) 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 (copolymer weight 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 material-6-10 Photographic layer, intermediate layer, surface protective layer first layer, surface protective layer second layer are coated simultaneously in the order of the undercoat surface by the slide bead coating method, and photothermographic material is prepared. Samples of material were made. 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 coated silver amount of the image forming layer was 0.821 g / m ² per side in total of the fatty acid silver and the silver halide. This was applied to both sides of the support.
Table 3 shows the relationship between the silver halide emulsion used and the coated sample.

The coating amount (g / m ² ) per side of each compound in the image forming layer is as follows.
Fatty acid silver 2.80
Polyhalogen compound-1 0.028
Polyhalogen compound-2 0.094
Silver iodide complex forming agent 0.46
SBR latex 5.20
Reducing agent-1 0.33
Reducing agent-2 0.13
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) 0.146

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 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 to 45 ° C. and a wet bulb temperature of 15 to 21 ° C. in a helical contactless dryer.
After drying, the humidity is adjusted at 25 ° C. and humidity of 40-60% RH.
Subsequently, the film surface was heated to 70 to 90 ° C., and after the heating, the film surface was cooled to 25 ° C.

  The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the image forming layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the image forming layer surface side was measured and found to be 6.0.

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

5). Evaluation 1) Exposure and development The obtained samples were cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows.

(Packaging material)
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.

The double-sided coated photosensitive material thus prepared was evaluated as follows.
An X-ray regular screen HI-SCREEN B3 (using CaWO ₄ as the phosphor, emission peak wavelength: 425 m) made by FUJIFILM Co., Ltd. is used, and a sample is sandwiched between them to create an image forming assembly. did. 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. After the exposure, heat development was performed under the following heat development conditions. The obtained image was evaluated with a densitometer.

  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.

2) Evaluation items (sensitivity and fog evaluation)
The density of the obtained image was measured with a densitometer, and a density characteristic curve with respect to the logarithm of the exposure amount was created. The optical density of the unexposed portion was defined as the fog density (Dmin), the reciprocal of the exposure amount at which an optical density of 1.5 was obtained was defined as the sensitivity, and the density of the sample 1 was expressed as a relative value. The smaller the value of the fog, the better and the better performance.
(Evaluation of image preservation (printout))
The obtained image was stored under a fluorescent lamp with an illuminance of 1000 Lux for 24 hours, and then the increase in the cover density (ΔDmin) of the Dmin part was evaluated. The smaller the value, the better the image storability (printout property).

3) Evaluation results The results are shown in Table 3.
As can be easily recognized by examining the data shown in Table 3, the tabular grains of the present invention are excellent in high sensitivity, low fog and image stability during storage after processing.
On the other hand, a regular photosensitive material RX-U of a wet development system manufactured by Fuji Photo Film Co., Ltd. is exposed under the same conditions, and an automatic development processor CEPROS-M2 and processing solution CE-D1 manufactured by Fuji Photo Film Co., Ltd. are exposed. For 45 seconds.
As a result of comparing the photographic properties of the image obtained by the photothermographic material of the present invention and the image obtained by the wet development system, it was found that the performance was equivalent.

Claims (12)

  A method for preparing a silver halide emulsion comprising tabular silver halide grains having an average silver iodide content of 40 mol% or more and 50% or more of the total projected area having an aspect ratio of 2 or more, comprising: A method for preparing a silver halide emulsion, comprising forming grains in the presence of a solvent.   2. The method for preparing a silver halide emulsion according to claim 1, wherein the addition amount of the silver halide solvent is increased during grain formation.   3. The method for preparing a silver halide emulsion according to claim 1, wherein the silver halide solvent is allowed to coexist from the time of nucleation.   The silver halide emulsion according to any one of claims 1 to 3, wherein the silver halide solvent is a compound containing at least one atom selected from a sulfur atom, a selenium atom, and a tellurium atom. Preparation method. The method for preparing a silver halide emulsion according to any one of claims 1 to 4, wherein the silver halide solvent is a compound represented by the general formula (I).

In the general formula (I), L _a1 and L _a3 independently represent an aliphatic group, an aromatic hydrocarbon group, or a heterocyclic ring, and L _a2 represents a divalent aliphatic group or a divalent aromatic group. It represents a hydrocarbon group, a divalent substituted or unsubstituted heterocyclic linking group or a linking group combining them. Aa ₁ and Aa ₂ each independently represent —S—, _—Se— , _—Te— , —O—, —NR _a20 —, —CO—, —SO ₂ —, or a combination thereof. r represents an integer of 0 to 10. Further, L _a1, L _a3 is _{-SO 3 M a1, -PO 3 M} a2 M a3, -NR a1 (R a2), - N + R a3 (R a4) (R a5) · X a1 -, -SO ₂ NR _a6 (R _a7 ), -NR _a8 SO ₂ R _a9 , -CONR _a10 (R _a11 ), -NR _a12 COR _a13 , -SO ₂ R _a14 , -PO (-NR _a15 (R _a16 )) ₂ ,- NR _a17 CONR _a18 (R _a19 ), _{—COOM a4} or a heterocyclic group may be substituted. M _a1 , M _a2 , M _a3 , and M _a4 each independently represent a hydrogen atom or a counter cation. R _{a1 to} R _a20 each independently represent a hydrogen atom, an aliphatic group or an aromatic hydrocarbon group, and X _a1 ⁻ represents a counter anion. However, at least one of A _a1 and A _a2 represents -S- or -Se- or -Te-. The method for preparing a silver halide emulsion according to any one of claims 1 to 4, wherein the silver halide solvent is a compound represented by the general formula (II).

In the general formula (II), X _b and Y _a are independently of each other an aliphatic group, an aromatic hydrocarbon group, a heterocyclic group, —N (R _b1 ) R _b2 , —N (R _b3 ) N (R _b4 ) _Rb5 , _-ORb6 or _-SRb7 is represented. X _b and Y _b may form a ring. Xb and Yb may be substituted with a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, an amino group or an ammonium group, or a hydroxyl group. R _b1 , R _b2 , R _b3 , R _b4 , and R _b5 each independently represent a hydrogen atom, an aliphatic group, an aromatic hydrocarbon group, or a heterocyclic group, and R _b6 and R _b7 are independent from each other. Represents a hydrogen atom, a cation, an aliphatic group, an aromatic hydrocarbon group or a heterocyclic group.   A silver halide light-sensitive material comprising a silver halide prepared by the method for preparing a silver halide emulsion according to any one of claims 1 to 6.   A photothermographic material having an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder on the same surface of a support, wherein the photosensitive silver halide is claimed. A photothermographic material, which is a photosensitive silver halide prepared by the method according to any one of claims 1 to 6.   A photosensitive material containing tabular silver halide grains having an average silver iodide content of 40 mol% or more and 50% or more of the total projected area having an aspect ratio of 2 or more, comprising the silver halide grains A silver halide light-sensitive material, wherein a silver halide solvent is contained in at least one of the layer and the adjacent layer.   The silver halide photosensitive material according to claim 7, wherein the silver halide solvent is represented by the general formula (I).   The silver halide photosensitive material according to claim 7, wherein the silver halide solvent is represented by the general formula (II).   12. The silver halide photosensitive material according to claim 9, wherein the silver halide photosensitive material is a photothermographic material.