JP2005077723A - Heat developing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developing apparatus capable of preventing the occurrence of uneven development, by uniformly heating a heat developable recording material. <P>SOLUTION: The heat developing apparatus 10 comprises a liquid reservoir 2 in which a liquid heat supply medium W is contained, a heating means 3 to heat the heat supply medium W, and a conveying means 4 to make the heat developable recording material F pass through the heat supply medium W, thereby heat-treating the medium. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat development apparatus for thermally developing a heat development recording material on which a latent image is formed.

In recent years, a recording apparatus using a heat-sensitive recording material (hereinafter referred to as a recording material) such as a photosensitive and / or heat-sensitive recording material (photosensitive heat-sensitive recording material) or a film of a heat-developable photosensitive material has been proposed, and digital radiography. It is applied as an image recording apparatus for recording medical images such as systems, CT, and MRI.
In such a recording apparatus, a latent image is formed by irradiating (scanning) the recording material with a laser beam in the exposure part, and then the thermal development is performed by bringing the recording material into contact with the heating means in the thermal development part. The recording material on which the image is formed is discharged out of the apparatus (for example, Patent Document 1).

JP 2000-321743 A

In the dry system described above, the heat developing unit uses a heating drum as a heating means, and an endless belt is wound around the heating drum at a predetermined angle, and the recording material is sandwiched and conveyed by the heating drum and the endless belt, and heat development is performed. However, due to deformation caused by bending of the recording material or foreign matter adhering to the surface, the heated portion of the recording material and the heating means are not uniformly adhered, and uneven development occurs. There was room for improvement. Particularly, since a high quality image is required for a medical image, the recording material has a higher sensitivity. If the contact state with the heating drum is slightly uneven, the image quality is greatly deteriorated.
An object of the present invention is to provide a heat development apparatus capable of preventing the occurrence of uneven development by uniformly heating a heat development recording material.

  The above object of the present invention is a heat development apparatus for thermally developing a heat-developable recording material on which a latent image has been formed, a liquid storage section containing a liquid heat supply medium, and heating for heating the heat supply medium. This is achieved by a heat development apparatus comprising: a means for conveying the heat development recording material through the heat supply medium and performing a heat treatment.

  The heat development apparatus according to the present invention is configured such that a liquid heat supply medium accommodated in a liquid reservoir is heated by a heating means, and the heat development recording material passes through the heated heat supply medium by a conveying means. . Thus, heat development can be performed by heat-treating the heat-developable recording material. In the heated heat supply medium, the heat-developable recording material comes into contact with the heat supply medium and is heated uniformly. For this reason, this thermal development apparatus can thermally develop the thermal development recording material without causing unevenness.

  In the above heat development apparatus, it is preferable that the heat supply medium is a liquid which is inactive with respect to the heat development recording material. In this way, even when it comes into contact with the image forming layer provided on the heat-developable recording material, it does not get wet (not compatible), and only heat can be transferred to the heat-developable recording material. Examples of the inert liquid include mercury, hydrocarbon fluoride, gallium, and the like (including alloys) that are in a liquid state at a development temperature (50 ° C. to 100 ° C.).

  In the heat developing apparatus, it is preferable that the heat supply medium is a liquid metal. In this way, by using a metal having good thermal conductivity as the heat supply medium, it becomes possible to more efficiently transfer the heat quantity of the heating means to the heat-developable recording material.

  In the heat development apparatus, the heat supply medium is, for example, mercury.

  According to the present invention, it is possible to provide a heat development apparatus capable of preventing the occurrence of uneven development by uniformly heating a heat development recording material.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram for explaining a heat development apparatus according to the present invention. FIG. 2 is a cross-sectional view showing a heat developing section of the heat developing apparatus shown in FIG. FIG. 3 is a schematic sectional view showing the structure of the heat-developable recording material used in the present invention.
As shown in FIG. 1, the thermal development apparatus 10 includes a main body 10a, a cassette insertion portion 10b into which a cassette C that holds a thermal development recording material F on which a latent image to be thermal development is previously formed is inserted, The heat developing unit 1 that heat-develops the heat-developable recording material F taken out from the cassette C inserted into the cassette insertion unit 10b, the transport roller 12 that transports the heat-developed heat-developable recording material F, and the heat-developed recording material F. A cooling section 13 for appropriately cooling the heat-developable recording material F, a discharge roller 14 for discharging the heat-developable recording material F to the outside of the main body 10a, and a tray 15 for holding the heat-developable recording material F discharged from the discharge roller 14. It has.

  The conveyance path of the heat-developable recording material F in the heat development apparatus 10 will be described along the conveyance direction. First, the heat-developable recording material F accommodated and held in the cassette C is taken out at the cassette insertion portion 10 b and conveyed to the heat-developing portion 1. The heat development recording material F is thermally developed in the heat development unit 1 and conveyed to the cooling unit 13 via the conveyance roller 12, and then discharged from the discharge roller 14 to the tray 15.

  The heat developing apparatus 10 includes a pair of transport rollers 7 and 8, and the heat development recording material F is transported to the heat developing unit 1 by one transport roller 7 of the pair of transport rollers 7 and 8. The heat-developable recording material F thermally developed from the heat developing unit 1 by the transport roller 8 is transported to the downstream side of the transport path. A pair of conveyance parts 7 and 8 are a pair of nip rollers, respectively.

  As shown in FIG. 2, the thermal development unit 1 includes a bathtub 2, and mercury W is accommodated in the bathtub 2 as a liquid heat supply medium. In this embodiment, the bathtub 2 functions as a liquid storage part. It is preferable that the bathtub 2 is comprised from the metal with favorable heat conductivity.

  The liquid heat supply medium is not limited to mercury used in this embodiment, and other inert liquids can be used. Here, it is preferable to use an inert liquid because it does not get wet (not compatible) even when it comes into contact with the image forming layer provided on the heat-developable recording material, and only heat can be transferred to the heat-developable recording material. Examples of the inert liquid include mercury, hydrocarbon fluorides, gallium and the like, metals (including alloys) that are in a liquid state at a development temperature (50 ° C. to 100 ° C.), and the like.

Further, the heat developing unit 1 includes a heating member 3 disposed so as to contact the outer bottom surface of the bathtub 2. In the present embodiment, the heating member 3 functions as a heating means, and a planar heater such as a rubber heater can be used. However, the heating member 3 is not limited to a rubber heater. However, when a planar heater such as a rubber heater is used, the entire bathtub 2 can be efficiently heated by being attached so as to cover the entire lower surface of the bathtub 2, and is bulky when attached to the bathtub 2. The increase in size of the apparatus can be suppressed.
A driving unit 5 is connected to the heating member 3, and the driving unit 5 can switch the heating member 3 between ON and OFF and set the heating amount of the heating member 3.

  In the bathtub 2, a plurality (five in the present embodiment) of conveying units 4a, 4b, 4c, 4d, and 4e are provided as conveying means. These transport units 4a, 4b, 4c, 4d, and 4e are constituted by a pair of roller members, and pass the heat-developable recording material F transported from one transport roller 7 while being immersed in the heat supply medium, while the other To the transport roller 8.

The process of heat-treating the heat-developable recording material F by the heat-developing unit 1 of this embodiment will be described.
First, the drive part 5 is driven and the bathtub 2 is heated by heating the heating member 3, and the mercury W, which is a heat supply medium accommodated in the bathtub 2, is heated. Then, while the mercury W is heated to a predetermined temperature, as shown by an arrow in FIG. 2, the heat-developable recording material F passes through the one of the conveying rollers 7 and the conveying means while being immersed in the mercury W. Let

  When the heat-developable recording material F is heated, the mercury W is preferably set to 110 ° C. to 130 ° C., more preferably around 120 ° C. Further, at this time, it is preferable that the time taken for the heat-developable recording material F to pass in a state of being immersed in mercury W is about 10 to 24 seconds.

  A heat sink may be provided on the inner wall surface 2 a of the bathtub 2. In this way, when the bathtub 2 is heated, the heat of the bathtub 2 is transferred from the heat sink to the mercury W accommodated therein, so that the mercury W can be raised more smoothly to a predetermined temperature. it can.

  FIG. 3 is a schematic sectional view showing the heat development recording material F used in the heat development apparatus according to the present invention. The heat-developable recording material F is roughly composed of a base F10 and an image forming layer F11 having an emulsion formed on both surfaces of the base F10.

According to the heat development apparatus 10 of the present embodiment, mercury W, which is a liquid heat supply medium accommodated in the bathtub 2, is heated by the heating member 3, and the heat development recording material F is conveyed in the heated mercury W. By passing by means 4, the heat-developable recording material F is subjected to heat treatment and thermally developed. When the heat-developable recording material F passes through the heated mercury W, the heat-developable recording material F comes into contact with the mercury W particles so that the whole is uniformly heated. For this reason, this heat developing apparatus 10 can heat-develop the heat-developable recording material F so that unevenness does not occur.
That is, when the heat development apparatus 10 is brought into contact with the heating member due to distortion of the heat development recording material, as in a conventional heat treatment in which the heat development recording material F is brought into direct contact with a heating member such as a heating drum. It is possible to prevent development unevenness from occurring in the heat-developable recording material that has been heat-developed due to uneven heating.
Further, since the heat development apparatus 10 does not directly contact the heat development recording material F with the heating member, it is possible to avoid peeling by reducing the external pressure applied to the image forming layer F11 of the heat development recording material F. it can.

  In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.

The photothermographic material used in the thermal development apparatus according to the present invention will be described in detail below.
The photographic photosensitive material used in this embodiment does not write image information by scanning exposure with a laser beam or the like, but records an image by surface exposure.
Conventionally, it is commonly used in the field of wet-developable photosensitive materials, and in medical applications, it is a double-sided or single-sided photosensitive film (X-ray film), a mammograph film, various plate-making films for printing, an industrial recording film, or a film for photographing with a general camera. It has been known. For example, a photothermographic material for double-coated X-rays using a blue fluorescent intensifying screen (see, for example, Japanese Patent No. 3229344), a photothermographic material using silver iodobromide tabular grains (for example, (See JP-A-59-142539.) Alternatively, a medical photosensitive material in which tabular grains having a high silver chloride content and having a (100) main plane are coated on both sides of a support is also disclosed in the patent literature ( For example, refer to JP-A-10-282606.) Further, the double-sided photothermographic material is also disclosed in other patent documents (for example, JP-A-2000-227642, JP-A-2001-22027, JP-A-2001-109101, JP-A-2002). -See 90941.) However, in these known examples, when fine grain silver halide of 0.1 μm or less is used, the haze is not deteriorated but the sensitivity is low, and it is not practical for photography, while 0.5 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 silver iodide tabular grains as silver halide grains are known in the field of wet development (see, for example, JP-A-59-119344 and JP-A-59-119350). 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.

As the photothermographic material satisfying the above requirements, the following are useful.
1. Photothermographic material The photothermographic material of this embodiment has an image forming layer containing a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one surface of a support. Yes. Moreover, it is preferable to have a surface protective layer on the image forming layer, or a back layer or a back protective layer on the opposite side.
The configuration of each layer and preferred components thereof will be described in detail.

(Compound that effectively reduces visible light absorption derived from photosensitive silver halide after heat development)
In this embodiment, it is preferable to contain a compound that effectively reduces the visible light absorption derived from the photosensitive silver halide after heat development compared to before heat development.
In the present embodiment, it is particularly preferable to use a silver iodide complex-forming agent as a compound that practically reduces visible light absorption derived from photosensitive silver halide after heat development.

(Description of silver iodide complex forming agent)
The silver iodide complex-forming agent in the present embodiment contributes to a Lewis acid-base reaction in which at least one of a nitrogen atom or a sulfur atom in the compound donates electrons 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 silver ions, iodide ions, 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.

  Although the mechanism of action of the silver iodide complex-forming agent in this embodiment has not been clearly elucidated, silver iodide is solubilized by forming a stable complex composed of at least ternary components including iodide ions and silver ions. Presumed to be. The silver iodide complex-forming agent in the present embodiment has a poor ability to solubilize silver bromide and silver chloride, but acts specifically on silver iodide.

  Although details of the mechanism by which the image storage stability is improved by the silver iodide complex forming agent in the present embodiment are not clear, at least a part of the photosensitive silver halide and the silver iodide complex forming agent in the present embodiment are heated. This is due to the fact that a complex is formed by reacting during development and the photosensitivity is lowered or disappeared. In particular, it is considered that the image storability under light irradiation is greatly improved. At the same time, it is also a great feature that clear high-quality images can be obtained as a result of the reduction of film turbidity due to silver halide. The turbidity of the film can be confirmed by the decrease in the UV-visible absorption of the spectral absorption spectrum.

  In the present embodiment, 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 embodiment is clearly different from the conventional silver ion complex forming agent in that the iodide ion is essential for forming a stable complex. The conventional silver ion complex forming agent has a dissolution action on a salt containing silver ions such as an organic silver salt such as silver bromide, silver chloride, or silver behenate, whereas the silver iodide complex in the present embodiment. The forming agent is greatly characterized in that it does not act unless silver iodide is present.

  Specific compounds of the silver iodide complex forming agent in the present embodiment are the same as those described in detail in Japanese Patent Application Nos. 2002-367661, 2002-367661, and 2002-367663. Specific examples of compounds described in these patent application specifications can also be given as specific examples of the compound of the present embodiment.

  In this embodiment, in order to greatly improve the image storage stability, particularly image storage stability under light irradiation, the absorption intensity of the ultraviolet-visible absorption spectrum of the photosensitive silver halide after heat development is In comparison, it is preferably 80% or less, more preferably 40% or less, and particularly preferably 20% or less. Most preferably, it is 10% or less.

The silver iodide complex-forming agent in this embodiment 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.

(Explanation of photosensitive silver halide)
1) Halogen composition It is important that the photosensitive silver halide used in this embodiment has a high silver iodide content of 40 mol% or more and 100 mol% or less. 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 photothermographic material in which image storage stability after development processing, in particular, an increase in fog due to light irradiation is remarkably small.

  Further, the silver iodide content is preferably 70 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, and further preferably 90 mol% or more and 100 mol% or less after the treatment. From the viewpoint of image storage stability against light irradiation, it is extremely preferable.

  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, and more preferably 2- to 4-fold core / shell particles can be used. 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 this embodiment can take 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 C.R.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. PhysicalReview, Volume 161, No. 3, p.848-851 (1967) can be referred to.

2) Grain size For the silver halide of high silver iodide used in this embodiment, a sufficiently large grain size necessary to achieve high sensitivity can be selected. In this embodiment, the average equivalent sphere diameter of silver halide is preferably 0.3 μm or more and 5.0 μm or less, and more preferably 0.5 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 that 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) Amount of application In general, in the case of a photothermographic material in which silver halide remains as it is after heat development, increasing the amount of silver halide applied decreases the transparency of the film and is undesirable in terms of image quality. Despite the request, it was low and limited. However, in the case of this embodiment, the haze of the film due to silver halide can be reduced by heat development treatment, so that more silver halide can be applied. In this invention, it is more preferable that they are 0.5 mol% or more and 100 mol% or less with respect to 1 mol of silver of a nonphotosensitive organic silver salt, Preferably they are 5 mol% or more and 50 mol% or less.

4) Grain formation method The formation method of photosensitive silver halide is well known in the art. For example, the method described in Research Disclosure No. 17029 in June 1978 and US Pat. No. 3,700,458 is used. Specifically, a method is used in which a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound to gelatin or another polymer solution, and then mixed with an organic silver salt. In addition, the method described in paragraph Nos. 0217 to 0224 of JP-A-11-119374, the method described in JP-A-11-352627, and Japanese Patent Application No. 2000-42336 are also preferable.
Regarding the method for forming tabular grains of silver iodide, the methods described in JP-A-59-119350 and 59-119344 are preferably used.

5) Grain shape Examples of the shape of the silver halide grains in the present embodiment include cubic grains, octahedral grains, tetradecahedral grains, dodecahedron grains, tabular grains, spherical grains, rod-shaped grains, and potato grains. . Preferred are dodecahedral grains, tetrahedral grains, and tabular grains. The dodecahedron referred to here is a particle having (001), {1 (-1) 0}, {101} faces, and the tetrahedral particle is a (001), {100}, {101} face. Particles. Here, {100} and {101} planes represent crystal plane groups having plane indices equivalent to the (100) and (101) planes, respectively.
Silver iodide dodecahedron, tetrahedron, and octahedron can be prepared with reference to Japanese Patent Application Nos. 2002-081020, 2002-87955, and 2002-91756.
The tabular grains have an aspect ratio of 2 or more, preferably 2 to 50.

  Although the silver halide having a high silver iodide content in the present embodiment can take a complicated form, a preferable form is, for example, p164-Fig1 of RLJENKINS etal. J of Phot. Sci. Vol. 28 (1980). And bonding particles as shown in FIG. Tabular grains as shown in Fig. 1 are also preferably used. Grains with rounded corners of silver halide grains can also be preferably used. The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the proportion of the [100] surface that has high spectral sensitization efficiency when adsorbed by the spectral sensitizing dye is high. preferable. The ratio is preferably 50% or more, more preferably 65% or more, and still more preferably 80% or more. The ratio of the Miller index [100] plane is described in T. Tani; J. Imaging Sci., 29, 165 (1985) using the adsorption dependence of the [111] plane and the [100] plane in the adsorption of sensitizing dyes. It can obtain | require by the method of.

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

In the present embodiment, 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- . In this embodiment, a hexacyano Fe complex is preferable.

  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 desalting method and a chemical sensitization method of a silver halide emulsion which can be contained in the silver halide grains used in this embodiment, JP-A-11 Paragraph Nos. 0046 to 0050, Paragraph Nos. 0025 to 0031 of JP-A-11-65021, Paragraph Nos. 0242 to 0250 of JP-A-11-119374.

7) Gelatin As the gelatin contained in the photosensitive silver halide emulsion used in this embodiment, various gelatins can be used. In order to maintain a good dispersion state of the photosensitive silver halide emulsion in the organic silver salt-containing coating solution, it is preferable to use a low molecular weight gelatin having a molecular weight of 500 to 60,000. These low molecular weight gelatins may be used at the time of particle formation or dispersion after desalting, but are preferably used at the time of dispersion after desalting.

8) Chemical sensitization The photosensitive silver halide used in this embodiment may be non-chemically sensitized, but is chemically sensitized by at least one of chalcogen sensitization, gold sensitization, and reduction sensitization. It is preferable. 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 (eg dimorpholine disulfide, cystine, lenthionine (1,2,3,5,6-pentathiepane)), polythionates, elemental sulfur and active gelatin Can also be used That. Particularly preferred are thiosulfates, thioureas and rhodanines.

  In selenium sensitization, unstable selenium compounds are used, and Japanese Patent Publication Nos. 43-13489, 44-15748, JP-A-4-25832, 4-109340, 4-271341, and 5-40324. 5-11385, Japanese Patent Application Nos. 4-202415, 4-330495, 4-333030, 5-4203, 5-4204, 5-106977, 5-236538. Selenium compounds described in JP-A-5-241642 and JP-A-5-286916 can be used.

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

  In the 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 preferred, particularly the compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, the general formula (II) in JP-A-5-313284, Compounds represented by (III) and (IV) are more preferred.

  In particular, in the chalcogen sensitization of this embodiment, 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 are also used. 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 this embodiment, 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) After spectral sensitization, there may be (4) immediately before application.

The amount of chalcogen sensitizer used in the present embodiment varies depending on the silver halide grains used, chemical ripening conditions, etc., but is 10 ⁻⁸ to 10 ⁻¹ mol, preferably 10 ⁻⁷ , per mol of silver halide. About 10 ⁻² mol is used.
Similarly, the amount of the gold sensitizer used in the present embodiment varies depending on various conditions, but as a guideline, it is 10 ⁻⁷ mol to 10 ⁻² mol, more preferably 10 ⁻⁶ mol, per mol of silver halide. ~ 5x10 ^-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 embodiment, in addition to chalcogen sensitization and gold sensitization, reduction sensitization can also be used in combination. 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 the reduction sensitizer, likewise may vary depending on various conditions, per mol of silver halide 10 ^-7 mol to 10 ^-1 mol as a guide, and more preferably 10 ^-6 mol to 5 × 10 ^{- 2} moles.

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

9) Compound in which one-electron oxidant produced by one-electron oxidation can emit one or more electrons In the photothermographic material of this embodiment, one-electron oxidant produced by one-electron oxidation is one electron. Or it is preferable to contain the compound which can discharge | release more electrons. The compound can be used alone or in combination with the above-described various chemical sensitizers, and can increase the sensitivity of silver halide.

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

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

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

  The compounds of types 1 to 4 of this embodiment are described in detail in JP-A No. 2003-114487, JP-A No. 2003-114486, JP-A No. 2003-140287, JP-A No. 2003-75950, and JP-A No. 2003-114488, respectively. It is the same as the compound explained in 1. Specific compound examples described in these patent publications can also be given as specific examples of the compounds of types 1 to 4 of the present embodiment. Moreover, the synthesis example of the compound of the type 1-4 of this embodiment is also the same as what was described in these patents.

  As specific examples of the compound of type 5 of this embodiment, further, JP-A-9-211769 (compounds PMT-1 to S-37 described in Table E and Table F on pages 28-32), JP-A-9-211774 No. 11-95355 (compounds INV1-36), JP-T-2001-99696 (compounds 1-74, 80-87, 92-122), US Pat. No. 5,747,235, US Pat. No. 5,747 236, European Patent No. 786692A1 (compounds INV1 to 35), European Patent No. 893732A1, US Pat. No. 6,054,260, US Pat. No. 5,994,051, etc. Examples of compounds referred to as “agents” or “deprotonated electron donating sensitizers” are mentioned as they are.

  The compounds of types 1 to 5 of this embodiment may be used at any time during the preparation of the photosensitive silver halide emulsion and during the process of manufacturing 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 types 1 to 5 of this embodiment 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 types 1 to 5 of this embodiment are preferably used in emulsion layers containing photosensitive silver halide and non-photosensitive organic silver salt, but photosensitive silver halide and non-photosensitive organic silver salt are used in combination. 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 this embodiment is preferably 1 × 10 ^{−9 to} 5 × 10 ⁻¹ mol, more preferably 1 × 10 ⁻⁸ to 1 mol per mol of silver halide, regardless of before and after the sensitizing dye. It is contained in the silver halide emulsion layer at a ratio of 5 × 10 ⁻² mol.

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

Formula (I) A- (W) n-B
[In the 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 adsorption 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 includes a cation such as alkali metal, alkaline earth metal, heavy metal (Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ag ⁺ , Zn ²⁺ etc.), ammonium ion, 4 Examples thereof include a heterocyclic group containing a classified nitrogen atom, and a phosphonium ion.
Further, the mercapto group as the adsorptive group may be tautomerized into a thione group.
The thione group as 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, or a “—S—” group, a “—Se—” group, a “—Te—” group, or a “═N—” group that can coordinate to a silver ion by 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, etc. , Thiazole group, oxazole group, benzothiophene group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole , Triazine 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 adsorbing 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 an —NH— group capable of forming imino silver (> NAg) as a partial structure of the heterocyclic ring (for example, benzotriazo Group, benzimidazole group, an indazole group), more preferable as an adsorptive group is a 2-mercaptobenzimidazole group, a 3,5-dimercapto-1,2,4-triazole group.

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

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

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

  Although the specific example of the reducing group represented by B below is illustrated, this embodiment is not limited to these. Here, * indicates a position where A or W is bonded in Formula (I).

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

  The adsorptive redox compound having an adsorbing group and a reducing group for silver halide in the molecule of the present embodiment is the same as the compound described in detail in Japanese Patent Application Nos. 2002-328531 and 2002-379884. Specific examples of the adsorptive redox having an adsorbing group for silver halide and a reducing group in the molecule described in these patent application specifications can also be given as specific examples of the compound of the present embodiment.

The compound of this embodiment can be easily synthesized according to a known method.
As the compound of the formula (I) of this embodiment, one type of compound may be used alone, but it is also preferable to use two or more types 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 method may be different.

The compound of formula (I) of this embodiment is preferably added to the silver halide emulsion layer, and more preferably added during the preparation of the emulsion. When added at the time of emulsion preparation, it can be added at any time during the process. For example, silver halide grain formation process, before the start of desalting process, desalting process, chemical ripening Examples include a step before starting, a chemical ripening step, and a step before preparing a finished emulsion. Moreover, it can also be added in several steps in these processes. Although it is preferably used 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) of the present embodiment can be added after being dissolved in water, a water-soluble solvent such as methanol, 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 embodiment can spectrally sensitize silver halide grains in a desired wavelength region when adsorbed on silver halide grains, and is suitable for the spectral characteristics of an exposure light source. Sensitizing dyes having spectral sensitivity can be advantageously selected. The photothermographic material of the present embodiment is preferably spectrally sensitized so as to have a spectral sensitivity peak particularly at 600 nm to 900 nm, or 300 nm to 500 nm. As for the sensitizing dye and the addition method, paragraphs 0103 to 0109 of JP-A No. 11-65021, compounds represented by Formula (II) of JP-A No. 10-186572, and compounds represented by Formula (I of JP-A No. 11-119374) ) And the dyes described in paragraph No. 0106, U.S. Pat.Nos. 5,510,236 and 3,871,887, Example 5, the dyes disclosed in JP-A-2-96131 and JP-A-59-48753, European Patent Publication No. 074364A1, 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, and the like. These sensitizing dyes may be used alone or in combination of two or more.

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

  In the present embodiment, a supersensitizer can be used to improve spectral sensitization efficiency. Examples of supersensitizers used in this embodiment include European Patent Publication No. 587,338, U.S. Pat.Nos. 3,877,943, 4,873,184, JP-A Nos. 5-341432, 11-109547, and 10-111543. And the compounds described in the above.

12) Combined use of silver halide The photosensitive silver halide emulsion in the photothermographic material used in the exemplary embodiment may be only one kind, or two or more kinds (for example, those having different average grain sizes and different halogen compositions). Those having different crystal habits, those having different chemical sensitization conditions) may be used in combination. The gradation can be adjusted by using a plurality of types of photosensitive silver halides having different sensitivities. As technologies related to these, JP-A-57-119341, 53-106125, 47-3929, 48-55730, 46-5187, 50-73627, 57-150841, etc. Can be mentioned. As the sensitivity difference, it is preferable that each emulsion has a difference of 0.2 logE or more.

13) Mixing of silver halide and organic silver salt It is particularly preferred that the photosensitive silver halide grains of this embodiment 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 effect of the present embodiment can be preferably obtained.

14) Mixing of silver halide into coating solution The preferred addition time of the silver halide of the present embodiment to the image forming layer coating solution is from 180 minutes before application, preferably from 60 minutes to 10 seconds before application. However, the mixing method and mixing conditions are not particularly limited as long as the effects of the present embodiment 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 delivered to the coater is the desired time, and by N. Harnby, MFEdwards, AWNienow, and translation by Koji Takahashi There is a method of using a static mixer described in Chapter 8 of “Liquid Mixing Technology” (published by Nikkan Kogyo Shimbun, 1989).

(Description of organic silver salt)
The non-photosensitive organic silver salt used in the present embodiment is relatively stable to light, but when heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide and a reducing agent. A silver salt that forms a silver image. The organic silver salt may be any organic material containing a source capable of reducing silver ions. Regarding such a 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. 0803684A1, European Patent Publication No. 0962812A1, 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 embodiment, 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 embodiment is not particularly limited, and may be a needle shape, a rod shape, a flat plate shape, or a flake shape.
In the present embodiment, a scaly organic silver salt is 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, further 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, respectively. 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 of measuring monodispersity, there is a method of obtaining from the standard deviation of the volume weighted average diameter of the organic silver salt, 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 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 temporal change of fluctuation of the scattered light. Can do.

  A known method or the like can be applied to the production and dispersion method of the organic acid silver used in the present embodiment. For example, the above-mentioned JP-A-10-62899, European Patent Publication No. 0803683A1, European Patent Publication No. 0962812A1, JP-A-11-349591, JP-A-2000-7683, JP-A-2000-72711, JP-A-2001-163827 JP-A-2001-163889-90, JP-A-11-203413, JP-A-2000-90093, JP-A-2000-195621, JP-A-2000-191226, JP-A-2000-213813, JP-A-2000-214155, JP-2000- You can refer to 191226 etc.

  In this embodiment, a photosensitive material can be produced by mixing an organic silver salt water dispersion and a photosensitive silver salt water dispersion. Mixing two or more organic silver salt aqueous dispersions and two or more photosensitive silver salt aqueous dispersions when mixing is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present embodiment can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably from 1 to 3 g / m ^2. Particularly preferred is 1.2 to 2.5 g / m ² .

(Description of reducing agent)
The photothermographic material of this embodiment 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 described in JP-A No. 11-65021, paragraph numbers 0043 to 0045, and European Patent No. 0803764, p. 7, line 34 to p. 18, line 12.

  A preferred reducing agent used in the present embodiment is a so-called hindered phenol-based reducing agent or a bisphenol-based reducing agent having a substituent at the ortho position of the phenolic hydroxyl group. 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.

  Although the specific example of a compound represented by general formula (R) of this embodiment is shown below, the compound of this embodiment is not limited to these.

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

The addition amount of the reducing agent in this embodiment is preferably from 0.01~5.0g / m ^2, more preferably from 0.1 to 3.0 g / m ^2, the surface having the image forming layer It is preferable that 5-50% mol is contained with respect to 1 mol of silver, and it is more preferable that it is contained by 10-40 mol%.

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

  The reducing agent of this embodiment 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.

(Description of development accelerator)
In the photothermographic material of this embodiment, a sulfonamide phenol compound represented by the general formula (A) described in JP-A-2000-267222, JP-A-2000-330234, or the like as a development accelerator, -92075, hindered phenol compounds represented by general formula (II), general formula (I) described in JP-A-10-62895, JP-A-11-15116, etc., Japanese Patent Application No. 2001-074278 A hydrazine-based compound represented by the general formula (1) described in the above 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 to 20 mol% with respect to the reducing agent, preferably in the range of 0.5 to 10 mol%, more preferably in the range of 1 to 5 mol%. 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 embodiment, among the above development accelerators, a hydrazine-based compound represented by the general formula (1) described in Japanese Patent Application No. 2001-074278 and a general formula (2) described in Japanese Patent Application No. 2000-76240. A phenolic or naphtholic compound represented by

  Hereinafter, preferred specific examples of the development accelerator of the present embodiment will be described, but the present embodiment is not limited thereto.

(Description of hydrogen bonding compound)
In the present embodiment, an aromatic hydroxyl group (—OH) of the reducing agent, 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 may be used in combination. preferable.

  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 this embodiment, a particularly preferred hydrogen bonding compound is a compound represented by the following general formula (D).

Formula (D)

In the general formula (D), R ²¹ to R ²³ each independently represents an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group, and these groups may be substituted even if they are unsubstituted. You may have.

When R ²¹ to R ²³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples thereof include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group. Preferred examples of the substituent include an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, and a t-octyl group. Group, phenyl group, 4-alkoxyphenyl group, 4-acyloxyphenyl group and the like.

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

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

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

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

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

R ²¹ to R ²³ are preferably an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. In view of the effect of this embodiment, 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 embodiment are shown below, but the present embodiment is not limited to these.

  Specific examples of the hydrogen bonding compound include those described in Japanese Patent Application Nos. 2000-192191 and 2000-194811 in addition to those described above.

  Like the reducing agent, the hydrogen bonding compound of this embodiment 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. The compound of the present embodiment forms a complex by a hydrogen bond with a compound having a phenolic hydroxyl group in a solution state, and depending on the combination of the reducing agent and the compound of the general formula (A) of the present embodiment, a crystalline state as a complex Can be isolated.

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

  It is preferable to use the hydrogen bonding compound of this embodiment in the range of 1-200 mol% with respect to a reducing agent, More preferably, it is the range of 10-150 mol%, More preferably, it is 30-100 mol%. It is a range.

(Description of binder)
The binder of the organic silver salt-containing layer of the present embodiment may be any polymer, and suitable binders are transparent or translucent and are 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 (for example, poly (vinyl Formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s , Poly (olefin) s, cellulose esters, and poly (amides). The binder may be coated from water or an organic solvent or emulsion.

  In this embodiment, 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 it is.

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 (ΣXi = 1) of the i-th monomer, 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, EHImmergut (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 embodiment, when the organic silver salt-containing layer is formed using a coating solution in which 30% by mass or more of the solvent is water and dried, the binder of the organic silver salt-containing layer is further an aqueous solvent. When it is soluble or dispersible in (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 the moisture content, for example, Polymer Engineering Course 14, Polymer Materials Testing Method (Edited by Polymer Society, Jinshokan) can be referred to.

  The equilibrium moisture content at 25 ° C. and 60% RH of the binder polymer of this embodiment is preferably 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and still more preferably 0.02%. Desirably, the content is from 1% by mass to 1% by mass.

  The binder of this embodiment 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 embodiment, preferred modes of the polymer dispersible in the aqueous solvent include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly (vinyl chloride), Hydrophobic polymers such as vinyl acetate), poly (vinylidene chloride) s, and poly (olefins) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer.

  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 emulsion 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, Tg61 ℃)
Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000, Tg59 ° C)
Latex of P-3; -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
Latex of P-4; -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg17 ° C)
Latex of P-5; -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg24 ℃)
Latex of P-6; -St (70) -Bu (27) -IA (3)-(crosslinkability)
Latex of P-7; -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg29 ° C)
Latex of P-8; -St (60) -Bu (35) -DVB (3) -MAA (2)-(crosslinkability)
P-9; -St (70) -Bu (25) -DVB (2) -AA (3)-latex (crosslinkable)
Latex of P-10; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-(molecular weight 80000)
P-11; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67000)
Latex of P-12; -Et (90) -MAA (10)-(molecular weight 12000)
P-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130000, Tg43 ℃)
P-14; -MMA (63) -EA (35) -AA (2) latex (molecular weight 33000, Tg47 ℃)
Latex of P-15; -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg23 ° C)
Latex of P-16; -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg20.5 ℃)

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

The polymer latex described above is also commercially available, and the following polymers can be used. Examples of acrylic polymers include Sebian A-4635, 4718, 4601 (above made by Daicel Chemical Industries, Ltd.), Nipol Lx811, 814, 821, 820, 857 (above made by Nippon Zeon Co., Ltd.), poly ( Examples of poly (urethanes) such as FINETEXES650, 611, 675, 850 (above Dainippon Ink & Chemicals), WD-size, WMS (above Eastman Chemical) , HYDRANAP10, 20, 30, 40 (above Dainippon Ink Chemical Co., Ltd.) and other examples of rubbers include LACSTAR 7310K, 3307B, 4700H, 7132C (above Dainippon Ink Chemical Co., Ltd.), NipolLx416, Examples of poly (vinyl chloride) such as 410, 438C, 2507 (above made by Nippon Zeon Co., Ltd.), examples of poly (vinylidene chloride) such as G351, G576 (above made by Nippon Zeon Co., Ltd.) Are examples of poly (olefins) such as L502, L513 (above Asahi Kasei Kogyo Co., Ltd.) Te may be Chemipearl S120, SA100 (all manufactured by Mitsui Petrochemical Co.) and the like.
These polymer latexes may be used alone or in combination of two or more as required.

  As the polymer latex used in this embodiment, a latex of styrene-butadiene copolymer 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 embodiment include the aforementioned P-3 to P-8, 14, 15, commercially available products LACSTAR-3307B, 7132C, Nipol Lx416, and the like.

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

  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 this embodiment 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.

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

The total binder amount of the image forming layer of this embodiment is preferably 0.2 to 30 g / m ² , more preferably 1 to 15 g / m ² . A crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added to the image forming layer of this embodiment.

  In the present embodiment, the solvent of the organic silver salt-containing layer coating solution of the photosensitive 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%).

(Description of antifogging agent)
This embodiment 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), Q represents an alkyl group, an aryl group or a heterocyclic group, Y represents a divalent linking group, n represents 0 or 1, Z ₁ and Z ₂ represent a halogen atom, X represents a hydrogen atom or an electron-withdrawing group.

  Q preferably represents a phenyl group substituted with an electron-withdrawing group in which Hammett's substituent constant σp takes a positive value. Regarding the Hammett substituent constant, Journal of Medicinal Chemistry, 1973, Vol. 16, No. 11, 1207-1216, etc. can be referred to.

Examples of such electron-withdrawing groups include halogen atoms (fluorine atoms (σp value: 0.06), chlorine atoms (σp value: 0.23), bromine atoms (σp value: 0.23), iodine atoms ( σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl (σp value: 0.33), trifluoromethyl (σp value: 0.54)), cyano Group (σp value: 0.66), nitro group (σp value: 0.78), aliphatic / aryl or heterocyclic sulfonyl group (for example, methanesulfonyl (σp value: 0.72)), aliphatic / aryl or Heterocyclic acyl groups (for example, acetyl (σp value: 0.50), benzoyl (σp value: 0.43)), alkynyl groups (for example, C≡CH (σp value: 0.23)), aliphatic / aryl Or heterocyclic oxycarbo Group (for example, methoxycarbonyl (σp value: 0.45), phenoxycarbonyl (σp value: 0.44)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), Examples thereof include a sulfoxide group, a heterocyclic group, and a phosphoryl group.
The σp value is preferably in the range of 0.2 to 2.0, more preferably in the range of 0.4 to 1.0.

  Preferred as the electron-withdrawing group are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, an alkylphosphoryl group, a carboxyl group, an alkyl or arylcarbonyl group, and an arylsulfonyl group, and particularly preferably a carbamoyl group, an alkoxycarbonyl group, An alkylsulfonyl group and an alkylphosphoryl group, and a carbamoyl group is most preferred.

X is preferably an electron-withdrawing group, more preferably a halogen atom, aliphatic / aryl or heterocyclic sulfonyl group, aliphatic / aryl or heterocyclic acyl group, aliphatic / aryl or heterocyclic oxycarbonyl group, carbamoyl A sulfamoyl group, particularly preferably a halogen atom.
Among the halogen atoms, a chlorine atom, a bromine atom and an iodine atom are preferable, a chlorine atom and a bromine atom are more preferable, and a bromine atom is particularly preferable.

Y preferably represents —C (═O) —, —SO— or —SO ₂ —, more preferably —C (═O) — or —SO ₂ —, and particularly preferably —SO ₂ —. . n represents 0 or 1, and is preferably 1.

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

The compound represented by the general formula (H) of the present embodiment is preferably used in the range of 10 ^{−4 to} 0.8 mol, more preferably 10 ⁻ , per mol of the non-photosensitive silver salt in the image forming layer. It is preferably used in the range of ^{3 to} 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 embodiment is used, the amount of the compound of the general formula (H) is important in order to obtain a sufficient fog prevention effect. It is most preferable to use in the range of × 10 ^{−3 to} 0.03 mol.

  In the present embodiment, examples of the method for causing the compound represented by the general formula (H) to be contained in 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 embodiment include those disclosed in the patents described in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021. In particular, organic halogen compounds represented by the formula (P) in Japanese Patent Application No. 11-87297, organic polyhalogen compounds represented by the general formula (II) in Japanese Patent Application Laid-Open No. 10-339934, and Japanese Patent Application No. 11-205330 The organic polyhalogen compounds described are preferred.

(Other antifoggants)
Examples of other antifoggants include mercury (II) salts of paragraph No. 0113 of JP-A-11-65021, benzoic acids of paragraph No. 0114 of the same, salicylic acid derivatives of JP-A-2000-206642, and formulas of JP-A-2000-221634 A formalin scavenger compound represented by (S), a triazine compound according to claim 9 of JP-A-11-352624, a compound represented by formula (III) of JP-A-61-11791, 4-hydroxy-6-6 And methyl-1,3,3a, 7-tetrazaindene and the like.

  Antifoggant, stabilizer and stabilizer precursor that can be used in this embodiment described in JP-A No. 10-62899, paragraph number 0070, European Patent No. 0080374A1, page 20, line 57 to page 21, line 7 And the compounds described in JP-A-9-281637 and JP-A-9-329864.

  The photothermographic material in this embodiment 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 embodiment, any amount of the azolium salt may be added, but it is preferably 1 × 10 ⁻⁶ mol or more and 2 mol or less, and more preferably 1 × 10 ⁻³ mol or more and 0.5 mol or less per 1 mol of silver.

(Other additives)
1) Mercapto, disulfide, and thiones In this embodiment, in order to suppress or promote development and control development, to improve spectral sensitization efficiency, to improve preservability before and after development, a mercapto compound, disulfide, etc. Compounds and thione compounds can be contained. Paragraph Nos. 0067 to 0069 of JP-A No. 10-62899, compounds represented by the general formula (I) of JP-A No. 10-186572 and paragraph Nos. In European Patent Publication No. 0808374A1, 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 present embodiment, 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 the acceleration of development, which is a problem in the silver halide emulsion having a high silver iodide content composition of the present embodiment, and sufficient developability and low fogging can be achieved by selecting an appropriate addition amount. Coexistence is possible.

3) Plasticizers and lubricants Plasticizers and lubricants that can be used in the photosensitive layer of this embodiment are described in paragraph No. 0117 of JP-A No. 11-65021. The slip agents are 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 embodiment has various dyes and pigments (for example, CIPigment Blue 60, CIPigment Blue 64, CIPigment Blue 15: 6) can be used. These are described in detail in WO98 / 36322, JP-A Nos. 10-268465, 11-338098, and the like.

5) Super-high contrast agent For the formation of a super-high contrast image suitable for printing plate making, it is preferable to add a super-high contrast agent to the image forming layer. As for the super-high contrast agent and its addition method and addition amount, the formulas 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 ( H), compounds of formulas (1) to (3), formulas (A) and (B), compounds of general formulas (III) to (V) described in Japanese Patent Application No. 11-91652 (specific compounds: Chemical Formula 21 to Chemical Formula 24) and the high contrast accelerator are described in paragraph No. 0102 of JP-A No. 11-65021 and paragraph Nos. 0194 to 0195 of JP-A No. 11-223898.

In order to use formic acid or formate as a strong fogging substance, it is preferably contained 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.
In the case of using an ultrahigh contrast agent in the photothermographic material of the present embodiment, 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 hydrating diphosphorus pentoxide (the coating amount per 1 m ^{2 of the} photosensitive material) may be a desired amount according to the performance such as sensitivity and fog, but is 0.1 to 500 mg / m ² is preferable, and 0.5 to 100 mg / m ² is more preferable.

(Preparation and application of coating solution)
The preparation temperature of the image forming layer coating solution of this embodiment 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. Moreover, it is preferable that the temperature of the image forming layer coating liquid immediately after the addition of the polymer latex is maintained at 30 ° C. or higher and 65 ° C. or lower.

2. Layer structure, other components

  The photothermographic material of this embodiment can have a non-photosensitive layer in addition to the image forming layer. The non-photosensitive layer consists of (a) a surface protective layer provided on the image forming layer (on the side farther from the support), (b) between the plurality of image forming layers and between the image forming layer and the protective layer. An intermediate layer provided between them, (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 in this embodiment can be provided with a surface protective layer for the purpose of preventing adhesion of an image forming layer. The surface protective layer may be a single layer or a plurality of layers. The surface protective layer is described in JP-A No. 11-65021, paragraph numbers 0119 to 0120 and Japanese Patent Application No. 2000-171936.

  As the binder for the surface protective layer of the present embodiment, 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 0.3 to 4.0 g / m ² of polyvinyl alcohol coating amount as (per support 1 m ²⁾ is the protective layer (per one layer), 0.3 to 2.0 g / m ² is more preferable.

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

2) Antihalation layer In the photothermographic material of the present embodiment, the antihalation layer can be provided on the side farther from the exposure light source than the photosensitive layer. 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, etc.

  The antihalation layer contains an antihalation dye having absorption at the exposure wavelength. When the exposure wavelength is in the infrared region, an infrared absorbing dye may be used, and in that case, a dye having no absorption in the visible region is preferable.

  When antihalation is performed using a dye having absorption in the visible range, it is preferable that the dye color does not substantially remain after image formation, and a means for decoloring by the heat of heat development is used. In particular, it is preferable to add a thermally decolorable dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These techniques are described in JP-A-11-231457 and the like.

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

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

  In the thermal decoloration using such decoloring dye and base precursor, substances that lower the melting point by 3 ° C. or more when mixed with a base precursor as described in JP-A-11-352626 (for example, diphenylsulfone, 4-chlorophenyl, etc.) (Phenyl) sulfone) is preferably used in view of thermal decoloring properties.

3) Back Layer Back layers that can be applied to this embodiment are described in paragraph numbers 0128 to 0130 of JP-A No. 11-65021.

In the present embodiment, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver color tone and the temporal change of the image. Such colorants are disclosed in JP-A Nos. 62-210458, 63-104046, 63-103235, 63-208846, 63-306436, 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 this embodiment, 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 paragraph Nos. 0126 to 0127 of JP-A No. 11-65021.
The matting agent is preferably 1 to 400 mg / m ² , more preferably 5 to 300 mg / m ² in terms of the coating amount per 1 m ² of the photosensitive material.

  Further, the matte degree of the emulsion surface may be any as long as a so-called stardust failure in which small white spots occur in the image area and light leakage occurs, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less. It is preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness can be easily obtained by Japanese Industrial Standard (JIS) P8119 “Smoothness test method using Beck tester for paper and paperboard” and TAPPI standard method T479.

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

  In the present embodiment, 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 and the back layer of the present embodiment.
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 embodiment preferably has a film surface pH of 7.0 or less, more preferably 6.6 or less before the heat development process. The lower limit is not particularly limited, but is about 3. The most preferred pH range is in the range of 4 to 6.2.

  The film surface pH is preferably adjusted using an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is volatile and is preferable for achieving a low film surface pH because it can be removed before the coating process or heat development. In addition, it is also preferable to use ammonia in combination with a nonvolatile base such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. 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 embodiment.
As examples of hardeners, THJames'"THE THEORY OF THE PHOTOGRAPHIC PROCESS FOURTHEDITION" (Macmillan Publishing Co., Inc., published in 1977), each of the methods described on pages 77 to 87, chromium alum, 2,4 -Polychloro-6-hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfonacetamide), N, N-propylenebis (vinylsulfonacetamide), polyvalent metal ions described on page 78 of the same, Polyisocyanates such as US Pat. No. 4,281,060 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 effect of the present embodiment is 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 delivered to the coater is the desired time, and by N. Harnby, MFEdwards, AWNienow, Takahashi There is a method of using a static mixer or the like described in Chapter 8 of the translation of Koji "Liquid Mixing Technology" (published by Nikkan Kogyo Shimbun, 1989).

8) Surfactant Surfactants applicable to the present embodiment are described in paragraph No. 0132 of JP-A No. 11-65021.
In this embodiment, it is preferable to use a fluorochemical surfactant. Preferable specific examples of the fluorosurfactant include compounds described in JP-A-10-197985, JP-A-2000-19680, JP-A-2000-214554 and the like. In addition, polymeric fluorine-based surfactants described in JP-A-9-281636 are also preferably used. In the present embodiment, it is particularly preferable to use a fluorochemical surfactant described in Japanese Patent Application No. 2000-206560.

9) Antistatic Agent In the present embodiment, 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. For the antistatic layer, JP-A-11-65021, paragraph No. 0135, JP-A-56-143430, JP-A-56-143431, JP-A-58-62646, JP-A-56-120519, paragraphs of JP-A-11-84573 Techniques described in paragraph numbers 0078 to 0084 of US Pat. 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 this embodiment is not limited as long as the repeating structural unit is substantially composed of an ethylene-2,6-naphthalenedicarboxylate unit, and is not copolymerized polyethylene-2. , 6-Naphthalenedicarboxylate as well as a copolymer in which 10% or less, preferably 5% or less of the number of repeating structural units is modified with other components, and mixtures and compositions with other polymers Is included.

  Polyethylene-2,6-naphthalate is synthesized by conjugating naphthalene-2,6-dicarboxylic acid, or a functional derivative thereof, and ethylene glycol or a functional derivative thereof in the presence of a catalyst under suitable reaction conditions. However, one or more appropriate third components (modifiers) are added to the polyethylene-2,6-naphthalate referred to in the present embodiment before the completion of the 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-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 JP-A-11-106881, paragraphs 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-11-65021 may be added. Various additives are added to either the photosensitive layer or the non-photosensitive layer. For these, reference can be made to WO98 / 36322, EP803764A1, JP-A-10-186567, 10-18568 and the like.

12) Coating method The photothermographic material in this embodiment may be coated by any method. Specifically, various coating operations are used, including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in U.S. Pat. Stephen F. Kistler, Petert M. Schweizer "LIQUID FILM COATING" (CHAPMAN & HALL, 1997) pages 399 to 536, preferably used for extrusion coating or slide coating, particularly preferably used for slide coating It is done.

  An example of the shape of the slide coater used for slide coating is shown in Figure 11b.1 on page 427 of the same book. If desired, two or more layers can be simultaneously coated by the method described in pages 399 to 536 of the same document, the method described in US Pat. No. 2,761,791 and British Patent 837,095.

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

13) Packaging material The photothermographic material of the present embodiment is used to prevent deterioration of photographic performance during storage before use, or to prevent curling or curling in the case of a rolled product form. Preferably, the package is hermetically packaged 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 a 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 technologies that can be used Techniques that can be used for the photothermographic material of the present embodiment include EP803764A1, EP883022A1, WO98 / 36322, JP-A-56-62648, and 58-62644. Kaihei 9-43766, 9-281637, 9-297367, 9-304869, 9-311405, 9-329865, 10-10669, 10-62899, 10-69023 10-186568, 10-90823, 10-171063, 10-186565, 10-186567, 10-186569 to 10-186572, 10-197974, 10-197982, 10-197983, 10-197985 to 10-197987, 10-207001, 10-207004, 10-221807, 10-282601, 10 -288823, 10-288824, 10-307365, 10-312038, 10-339934, 11-7100, 11-15105, 11-24200, 11-24201 11-30832, 11-84574, 11-65021, 11-109547, 11-125880, 11-129629, 11-133536 to 11-133539, 11-133542, 11-133543, 11- 223898, 11-352627, 11-305377, 11-305378, 11-305384, 11-305380, 11-316435, 11-327076, 11-338096 No. 11-338098, No. 11-338099, No. 11-343420, No. 2000-187298, No. 2000-10229, No. 2000-47345, No. 2000-206642, No. 2000-98530, Examples include 2000-98531, 2000-112059, 2000-112060, 2000-112104, 2000-112064, and 2000-171936.

15) Color imaging The composition of a multicolor photothermographic material may comprise a combination of these two layers for each color and all components in a single layer as described in US Pat. No. 4,708,928. May be included.
In the case of a multicolor color photothermographic material, each emulsion layer generally uses a functional or non-functional barrier layer between each photosensitive layer, as described in US Pat. No. 4,460,681. Thus, they are kept distinguished from each other.

3. Image forming method 3-1. Exposure The photothermographic material of the present embodiment 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 this embodiment 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 according to the present embodiment is an orthogonal coordinate having an optical density (D) and an exposure amount (log E) equal to the coordinate axis unit length of an image obtained by stepwise exposure using X-rays and heat development. In the above 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, 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 a point of minimum density (Dmin) + density 1.6 is provided. It is preferably prepared. In the X-ray imaging system of the present embodiment, when a photothermographic material having such a characteristic curve is used, X-rays having excellent photographic characteristics such that the legs are extremely extended and the gamma is high in the medium density portion. An image 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 this embodiment 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 embodiment, preferable 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 embodiment 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 this embodiment 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 to 2.0 μm and large. The thing of a particle size has the preferable range of 10-30 micrometers.

(Single-sided photothermographic material)
The single-sided photothermographic material in this embodiment 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 embodiment, 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 embodiment may be developed by any method, but is usually developed by raising the temperature of the photothermographic material exposed imagewise. The preferred development temperature is 80 to 250 ° C, more preferably 100 to 140 ° C.
The development time is preferably 1 to 60 seconds, more preferably 5 to 30 seconds, and particularly preferably 5 to 20 seconds.

  As a thermal development system, a plate heater system may be used in addition to the system using the thermal development apparatus according to the present invention. The heat development method using a plate heater method is preferably a method described in JP-A-11-133572, in which a heat-developable photosensitive material on which a latent image has been formed is brought into contact with a heating means in a heat-development section to obtain a visible image In the developing device, the heating unit includes a plate heater, and a plurality of press rollers are disposed to face each other along one surface of the plate heater, and the heat is interposed between the press roller and the plate heater. A thermal development apparatus that performs thermal development by passing a development photosensitive material. It is preferable to divide the plate heater into 2 to 6 stages and lower the temperature about 1 to 10 ° C. at the tip.

  Such a method is also described in JP-A-54-30032, which can exclude moisture and organic solvents contained in the photothermographic material out of the system, and can be rapidly developed in 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 In addition to the thermal development apparatus according to the present invention, Fuji Medical Dry Imager-FM-DPL can be cited 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). Applications of this embodiment A photothermographic material using the high silver iodide photographic emulsion of this embodiment forms a black and white image by a silver image, and is a photothermographic material for medical diagnosis, a photothermographic material for industrial photography, It is preferably used as a photothermographic material for printing and a photothermographic material for COM.

  Hereinafter, the photothermographic material will be specifically described with reference to examples. However, the photothermographic material is not limited thereto.

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 in phenol / tetrachloroethane = 6/4 (weight ratio) at 25 ° C.) was obtained according to a conventional method. This was pelletized and dried at 130 ° C. for 4 hours. The film was colored blue with a blue dye (1,4-bis (2,6-diethylanilinoanthraquinone), then extruded from a T-die and quenched to prepare an unstretched film.

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

1-2. Surface Corona Treatment Both surfaces of the support were treated at room temperature at 20 m / min using a solid state corona treatment machine 6KVA model manufactured by Pillar. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

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

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

2. Preparation of coating materials 1) Silver halide emulsion (Preparation of silver halide emulsion A)
Add 4.3 ml of 1 wt% potassium iodide solution to 1421 ml of distilled water, then add 3.5 ml of 0.5 mol / L sulfuric acid, 36.5 g of phthalated gelatin, and 5 wt% methanol solution of 2,2 '-(ethylenedithio) diethanol. While the solution added with 160 ml was stirred in a stainless steel reaction vessel, the liquid temperature was kept at 75 ° C., and the solution A diluted with 218 ml by adding distilled water to 22.22 g of silver nitrate and 36.6 g of potassium iodide in 366 ml with distilled water Solution B was added in a total amount over 16 minutes at a constant flow rate, and Solution B was added by the control double jet method while maintaining pAg at 10.2. Thereafter, 10 ml of a 3.5 mass% aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10 mass% aqueous solution of benzimidazole was further added. Furthermore, Solution C diluted to 508.2 ml by adding distilled water to 51.86 g of silver nitrate and Solution D obtained by diluting 63.9 g of potassium iodide to 639 ml with distilled water were added in a total amount over 80 minutes at a constant flow rate. Solution D was added by the control double jet method while maintaining pAg at 10.2. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so as to be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and 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 emulsion A is a pure silver iodide emulsion, and tabular grains having an average projected area diameter of 0.93 μm, an average projected area diameter variation coefficient of 17.7%, an average thickness of 0.057 μm, and an average aspect ratio of 16.3 have a total projected area. It accounted for over 80%. The equivalent sphere diameter was 0.42 μm. As a result of analysis by X-ray powder diffraction analysis, 90% or more of silver iodide was present in the γ phase.

<< Preparation of silver halide emulsion B >>
One mole of tabular grain AgI emulsion prepared with silver halide emulsion A was placed in a reaction vessel. The pAg was 10.2 measured at 38 ° C. Then, by double jet addition, a 0.5 mol / liter KBr solution and a 0.5 mol / liter AgNO ₃ solution were added at 10 ml / min over 20 minutes to substantially add 10 mol% silver bromide to the AgI host. Epitaxially precipitated on the emulsion. During operation, pAg was maintained at 10.2. Furthermore, the pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 11.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% methanol solution of 1,2-benzisothiazolin-3-one was added, and the temperature was raised to 47 ° C. after 40 minutes. Sodium benzene thiosulfonate after 20 minutes of heating 7.6 × 10 ^-5 mol was added per mol of silver in methanol solution, per mol of silver 2.9 × 10 of tellurium sensitizer C in a methanol solution after 5 minutes ^{- 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 "-diethylmelamine was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the solution in methanol solution at 4.8 × 10 4 per mole of silver. ^-3 mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution with 5.4 × 10 ^-3 mol and 1- (3-methylureidophenyl)- Silver halide emulsion B was prepared by adding 5-mercaptotetrazole in an aqueous solution to 8.5 × 10 ⁻³ mol per mol of silver.

<< Preparation of silver halide emulsion C >>
In the same manner as silver halide emulsion A, the addition amount of 2,2 '-(ethylenedithio) diethanol in a 5% by weight methanol solution, the temperature at the time of grain formation, and the addition time of solution A were appropriately changed. Emulsion C was prepared. Silver halide Emulsion C is a pure silver iodide emulsion. Tabular grains having an average projected area diameter of 1.369 μm, an average projected area diameter variation coefficient of 19.7%, an average thickness of 0.130 μm and an average aspect ratio of 11.1 are 80% of the total projected area. Accounted for over 50%. The equivalent sphere diameter was 0.71 μm. As a result of analysis by X-ray powder diffraction analysis, 90% or more of silver iodide was present in the γ phase.

<< Preparation of silver halide emulsion D >>
A silver halide emulsion D containing 10 mol% of silver bromide epitaxial was prepared in exactly the same manner as the silver halide emulsion B except that the silver halide emulsion C was used.

≪Preparation of mixed emulsion for coating liquid≫
Dissolve silver halide emulsion B and silver halide emulsion D in a silver molar ratio of 5: 1, and add 7 × 10 ⁻³ mol of benzothiazolium iodide per mol of silver in a 1% by mass aqueous solution. did. Further, the amount of 1-electron oxidant produced by one-electron oxidation is such that compound compounds 1, 2 and 3 capable of emitting one or more electrons are each 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%, and in addition, 2% lignoceric acid, 2% arachidic acid, and 0.001% erucic acid were contained.
<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 of 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. Keep the reaction vessel containing 635L distilled water and 30L t-butyl alcohol 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 are 93 minutes and 15 seconds respectively at a constant flow rate. 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 value was a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, the average aspect ratio 2.1, and the coefficient of variation of the equivalent sphere diameter was 11%. It was a crystal. (A, b, and c are the provisions of the text)

  Add 19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water to a wet cake with a dry solid content of 260 kg. PM-10 type).

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

3) Preparation of reducing agent dispersion << Preparation of reducing agent-1 dispersion >>
Reducing agent-1 (2,2'-methylenebis- (4-ethyl-6-tert-butylphenol)) 10 kg and denatured polyvinyl alcohol (Kuraray Co., Ltd., POVAL MP203) 10 mass% aqueous solution 16 kg, water 10 kg Add and mix well to make a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 3 hours, and then 0.2 g of benzoisothiazolinone sodium salt Water was added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent-1 dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.
<< Preparation of Reducing Agent-2 Dispersion >>
10 mass of reducing agent-2 (6,6'-di-t-butyl-4,4'-dimethyl-2,2'-butylidenediphenol) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of% aqueous solution and mixed well to form 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 denatured polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203). Mix to make a slurry. This slurry was fed with a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 4 hours, and then 0.2 g of benzoisothiazolinone sodium salt Water was added to prepare a hydrogen bonding compound concentration of 25% by mass. This dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

5) Preparation of development accelerator dispersion and color tone modifier dispersion << Preparation of development accelerator-1 dispersion >>
To 10 kg of development accelerator-1 and 20 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), 10 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 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 so that the concentration of the development accelerator was 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 dispersions 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, 14 kg of water was added and mixed well to make 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. Then, 0.2 g of benzoisothiazolinone sodium salt Water was 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 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. Then, 0.2 g of benzoisothiazolinone sodium salt Water was added to adjust the concentration of the organic polyhalogen compound to 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
Dissolve 8 kg of modified polyvinyl alcohol MP203 in 174.57 kg of water, then add 3.15 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate and 14.28 kg of a 70% by weight aqueous solution of 6-isopropylphthalazine to form silver iodide complex A 5% by weight solution of the agent compound was prepared.

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

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

9) Preparation of SBR latex liquid << Preparation of SBR latex liquid >>
The 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 / liter NaOH 14.06 ml, ethylenediaminetetraacetic acid tetrasodium salt 0.15 g, styrene 255 g, acrylic acid 11.25 g, tert-dodecyl mercaptan 3.0 g, the reaction vessel was sealed and the stirring speed was 200 rpm. Stir with. 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 completion of the reaction, the internal temperature was lowered to room temperature, and then Na + ion: NH ₄ + ion = 1: 5 using 1 mol / liter NaOH and NH ₄ OH. To 3 (molar ratio) and adjusted to pH 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% by mass, equilibrium water content of 0.6% by mass at 25 ° C. and 60% RH, and ionic conductivity of 4.80 mS / cm. The same method is used for SBR latex having a pH of 8.4 Tg, and the ratio of styrene and butadiene is appropriately changed, using a conductivity meter CM-30S manufactured by Kogyo Co., Ltd., and measuring latex stock solution (44% by mass) at 25 ° C). Can be adjusted.

1-3-2. Preparation of coating solution 1) Preparation of emulsion layer (photosensitive layer) coating solution-1 To 1000 g of the fatty acid silver dispersion obtained above and 276 ml of water, an organic polyhalogen compound-1 dispersion and 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 Modifier-1 Dispersion, Mercapto Compound-1 Aqueous Solution, Mercapto Compound-2 Aqueous Solution were added sequentially, and after adding the silver iodide complex forming agent, the silver halide mixed emulsion for coating solution was silver immediately before coating. An amount of 0.22 mol per mol of fatty acid silver was added, mixed well, sent to a coating die as it was, and applied.

The viscosity of the emulsion layer coating solution was 25 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.
The viscosity of the coating solution at 25 ° C using the RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is 242, 65, 48, 26 at shear rates of 0.1, 1, 10, 100, and 1000 [1 / second], respectively. 20 [mPa · s].

  The amount of zirconium in the coating solution was 0.52 mg per 1 g of silver.

2) Preparation of emulsion layer 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 solution, 135ml of 20% aqueous solution of diammonium phthalate, total amount 10000g Water was added to the solution and adjusted with NaOH so that the pH was 7.5 to obtain an intermediate layer coating solution, which was then fed to the coating die so as to be 9.1 ml / m ² .
The viscosity of the coating solution was 58 [mPa · s] when measured with a B-type viscometer at 40 ° C. (No. 1 rotor, 60 rpm).

3) Preparation of emulsion 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 Cyana) 5 ml of 5% by weight aqueous solution (Mido), 0.5 g of phenoxyethanol and 0.1 g of benzoisothiazolinone, add water to make a total amount of 750 g, and use 26 ml of 4% by weight chromium alum immediately before coating. It was fed to a coating die so that a mixture with a static mixer to 18.6 ml / m ^2.
The viscosity of the coating solution was 20 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

4) Preparation of coating solution for emulsion layer protective layer second layer 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% solution, 5.4 ml of 2% solution of fluorosurfactant (F-1), 5.4 ml of 2% solution of fluorosurfactant (F-2), Aero 23 ml of 5% by mass solution of Zol OT (American Cyanamid Co., Ltd.), 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm, volume weighted average distribution 30%), polymethyl methacrylate fine particles (average particle size 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 sulfuric acid 44 ml, benzoisothiazolinone 10 mg with water added to a total amount of 650 g, 4 mass % Chromium alum and 0.67% by weight lid The aqueous solution 445ml containing an acid immediately before coating a mixture with a static mixer and a surface protective layer coating solution was fed to a coating die so that 8.3 ml / m ^2.
The viscosity of the coating solution was 19 [mPa · s] at a B-type viscometer of 40 ° C. (No. 1 rotor, 60 rpm).

1-4. Preparation of photothermographic material-1

A sample of a photothermographic material was prepared by simultaneous multilayer coating by the slide bead coating method in the order of the emulsion layer, the intermediate layer, the protective layer first layer, and the protective layer second layer from the undercoat surface. At this time, the emulsion layer and the intermediate layer were adjusted to 31 ° C., the protective layer first layer was adjusted to 36 ° C., and the protective layer second layer was adjusted to 37 ° C. The silver coating amount of the image forming layer was 0.821 g / m ² per side in total for the fatty acid silver and the silver halide. This was applied to both sides of the support.

The coating amount (g / m ² ) per side of each compound in the emulsion layer is as follows.
Silver behenate 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 wind at a dry bulb temperature of 10-20 ° C.
Non-contact conveyance and drying with a dry air with a dry bulb temperature of 23 to 45 ° C and a wet temperature of 15 to 21 ° C in a helical contactless contact dryer.
After drying, adjust the humidity at 25 ℃ and humidity 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 photosensitive layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.

  The chemical structures of the compounds used in the examples of this embodiment are shown below.

(Evaluation of photographic performance)
The obtained samples were cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50%, stored at room temperature for 2 weeks, and then evaluated as follows.
(Packaging material)
PET 10μ / PE 12μ / Aluminum foil 9μ / Ny 15μ / Polyethylene 50% containing carbon 3% Oxygen permeability: 0.02ml / atm ・ m ²・ 25 ℃ ・ day, moisture permeability: 0.10g / atm ・ m ²・ 25 ℃・ Day

The double-sided coated photosensitive material thus prepared was evaluated as follows.
An X-ray regular screen HI-SCREEN B3 manufactured by FUJIFILM Co., Ltd. (CaWO4 was used as the phosphor. Emission peak wavelength: 425 m) was used, and the sample was sandwiched between them to create an image forming assembly. . This assembly was subjected to X-ray exposure for 0.05 seconds, and X-ray sensitometry was performed. The X-ray apparatus used was a trade name DRX-3724HD manufactured by Toshiba Corporation, and a tungsten target was used. A voltage of 80 kVp was applied to the three phases with a pulse generator, and X-rays passed through a 7 cm water filter having absorption equivalent to that of the human body were used as a light source. The X-ray exposure was changed by the distance method, and step exposure was performed with a width of logE = 0.15. After the exposure, heat development was performed under the heat development conditions by the heat development apparatus according to the present invention. The obtained image was evaluated with a densitometer.

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 with the photothermographic material of the present embodiment and the image obtained by the wet development system, the performance was equivalent.

It is a schematic block diagram for demonstrating the heat developing apparatus concerning this invention. It is sectional drawing which shows the heat development part of the heat development apparatus shown in FIG. It is a schematic sectional drawing which shows the structure of the heat development recording material used by this invention.

Explanation of symbols

1 Heat development part 2 Bathtub (liquid storage part)
3 Heating means 4 Conveying means 10 Thermal development apparatus F Thermal development recording material

Claims (4)

A heat development apparatus for thermally developing a heat development recording material on which a latent image is formed,
A liquid storage unit in which a liquid heat supply medium is stored; a heating unit that heats the heat supply medium; and a transport unit that heat-processes the heat-developable recording material through the heat supply medium. A heat development apparatus characterized. 2. The heat development apparatus according to claim 1, wherein the heat supply medium is a liquid that is inert to the heat development recording material. The thermal development apparatus according to claim 1, wherein the heat supply medium is a liquid metal. The thermal development apparatus according to claim 1, wherein the heat supply medium is mercury.

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