JP2002318431A - Heat developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high development activity, eliminating delay in development, having high sensitivity, low Dmin and superior image preservability and less liable to fog in storage. SOLUTION: The heat developable photosensitive material has at least one photosensitive silver halide, a reducing agent for silver ions, a binder and non- photosensitive organic silver salt grains on one face of the base, the silver behenate content of the non-photosensitive organic silver salt grains is 90-100 mol% and the reducing agent is a compound of formula (I) wherein R<11> and R<11> ' are each a 1-20C alkyl; R<12> and R<12> ' are each H or a substituent substitutable on a benzene ring; L is -S- or -CHR<13> -, R<13> is H or a 1-5C alkyl; and X<1> and X<1> ' are each H or a group substitutable on a benzene ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material (hereinafter sometimes referred to as a "thermosensitive material"), and more particularly, to a photothermographic material having high development activity, high sensitivity and high image storability. The present invention relates to a photothermographic material having excellent heat resistance and less fog in a non-image area.

[0002]

2. Description of the Related Art In recent years, in the field of medical diagnostic films and photoengraving films, it has been strongly desired to reduce the amount of processing waste liquid from the viewpoint of environmental protection and space saving. Therefore, heat-development is possible as a medical diagnostic film and a photoengraving film that can be efficiently exposed by a laser imagesetter or a laser imager and can form a clear black image having high resolution and sharpness. There is a need for techniques relating to photosensitive materials. According to these photothermographic materials, a photothermographic processing system that does not require solution-based processing chemicals, is simpler and does not damage the environment can be supplied to customers.

[0003] In the field of general image forming materials, there are similar demands. Particularly, medical diagnostic images require fine depiction, so that high quality images with excellent sharpness and granularity are required. There is a feature that a cool black tone image is preferred from the viewpoint of easiness. At present, various hard copy systems using pigments and dyes, such as ink jet printers and electrophotographs, are distributed as general image forming systems, but none of them are satisfactory as output systems for medical images.

On the other hand, a thermal image forming system using an organic silver salt is disclosed in, for example, US Pat. Nos. 3,152,904 and 345.
No. 7075 and D.C. Crosta Bohr (Klos
terboer) "Heat Treated Silver System (Therm)
ally Processed Silver Systems) "(Imaging
Processings and Materials (Imaging Proc
esses and Materials) Neblette 8th edition, J.M. Sturge, V.S. Walworth, A.M.
Edited by Shepp, Chapter 9, p. 279, 198
9 years). In particular, photothermographic materials generally include a catalytically active amount of a photocatalyst (eg, silver halide),
It has a photosensitive layer in which a reducing agent, a reducible silver salt (for example, an organic silver salt), and if necessary, a color tone agent for controlling the color tone of silver are dispersed in a binder matrix. After the image exposure, the photothermographic material is heated to a high temperature (for example, 80 ° C. or higher), and a black silver image is formed by a redox reaction between a reducible silver salt (which functions as an oxidizing agent) and a reducing agent. Form. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, a black silver image is formed in the exposed area. U.S. Patent 2,910,377
No., JP-B-43-4924 and many other documents.

In the photothermographic material, it is preferable that the oxidation-reduction reaction between the reducible silver salt and the reducing agent proceeds at a practical reaction temperature and at a practical reaction time to obtain a sufficient image density. Therefore, at present, further development of a photothermographic material having high sensitivity, high development activity, and rapid reaction is desired.

Further, since a photothermographic material using an organic silver salt does not fix an organic silver salt or the like, even after a silver image is formed by heat, there is a possibility that a silver image appears by light / heat or the like. have. Of course, such a phenomenon does not occur in the normal use range, but, for example, when the processed film is placed in a car in the summertime for transportation or the like, it is very severe for the photothermographic material. When stored under the conditions, there are problems such as discoloration of the entire film, transfer of characters on the bag or the film where the film was stored, and the like, that is, fogging during storage.

On the other hand, a method for increasing the content of silver behenate in an organic silver salt is described in Japanese Patent Application Laid-Open No. H11-271920. No remarkable effect was found on development activity, image storability, and prevention of fogging during storage.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a photothermographic material having high development activity, eliminating delay in development, high sensitivity, low Dmin, excellent image storability, and little fogging during storage. .

[0009]

Means for solving the above problems are as follows. <1> A photothermographic material having at least one kind of photosensitive silver halide, a reducing agent for silver ions, a binder, and non-photosensitive organic silver salt particles on one surface of a support. The non-photosensitive organic silver salt particles have a silver behenate content of 90 mol% or more and 100 mol% or less, and the reducing agent is a compound represented by the following general formula (I). It is a photothermographic material.

[0010]

Embedded image

In the general formula (I), R ¹¹ and R ¹¹ ′ each independently represent 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 a —S— group or a —CHR ¹³ — group. R ¹³ is a hydrogen atom or carbon atom 1
To 5 alkyl groups. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

<2> In the compound represented by formula (I), R ¹¹ and R ¹¹ ′ each independently represent a group having 3 to 3 carbon atoms.
A secondary or tertiary alkyl group of R ¹² and R ¹² ′
Are each independently an alkyl group, L is a —CHR ¹³ — group, R ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and X ¹ and X ¹ ′ are hydrogen atoms. <1> The photothermographic material according to <1>.

<3> In the compound represented by the general formula (I), R ¹¹ and R ¹¹ ′ each independently represent a group having 3 to 3 carbon atoms.
A secondary or tertiary alkyl group of R ¹² and R ¹² ′
Are each independently a methyl or ethyl group, and L is -C
The photothermographic material according to <1> or <2>, wherein the photothermographic material is an HR ¹³ group, R ¹³ is a hydrogen atom, and X ¹ and X ¹ ′ are hydrogen atoms.

<4> The photothermographic material according to any one of <1> to <3>, wherein the non-photosensitive organic silver salt particles have a silver behenate content of from 94 mol% to 100 mol%. is there.

<5> The content of silver stearate in the non-photosensitive organic silver salt particles is 1 mol% or less, and the equivalent sphere diameter of the non-photosensitive organic silver salt particles is 0.05 μm or more.
The photothermographic material according to any one of <1> to <4>, which is not more than μm.

<6> The photothermographic material according to any one of <1> to <5>, wherein the non-photosensitive organic silver salt particles are scaly particles.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Photothermographic Material) The photothermographic material of the present invention will be described in detail below. The photothermographic material of the present invention comprises at least one surface on one side of a support.
Kinds of photosensitive silver halide, reducing agent for silver ion,
A binder and non-photosensitive organic silver salt particles, wherein the non-photosensitive organic silver salt particles have a silver behenate content of 90 mol% or more and 100 mol% or less, and the reducing agent has the following general formula (I) Is a compound represented by the formula:

[0018]

Embedded image

In the above formula (I), R ¹¹ and R ¹¹ ′ each independently represent 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 a —S— group or a —CHR ¹³ — group. R ¹³ is a hydrogen atom or carbon atom 1
To 5 alkyl groups. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

More specifically, the photothermographic material of the present invention comprises a layer containing at least one kind of photosensitive silver halide, a reducing agent for silver ions, a binder, and non-photosensitive organic silver salt particles (hereinafter referred to as a layer). , "Photosensitive layer") and a non-photosensitive layer. And it is preferable to have a back layer on the other surface of the support.

The photosensitive layer is composed of one or more layers, and when composed of one layer, a photosensitive silver halide, non-photosensitive organic silver salt particles, a reducing agent, and a binder are contained in the layer. Colorants, coating aids, and other auxiliaries as needed. On the other hand, when it is composed of two layers, the first layer (usually the layer adjacent to the support) contains photosensitive silver halide and non-photosensitive organic silver salt particles, and the second layer or both layers Contains several other components.

The non-photosensitive layer includes a protective layer provided on the photosensitive layer (on the side far from the support), an intermediate layer provided between a plurality of photosensitive layers or between the photosensitive layer and the protective layer. ,
Examples include an undercoat layer provided between the photosensitive layer and the support. It is preferable to provide a back layer on the other surface of the support (the side opposite to the side on which the photosensitive layer is provided).

<Non-photosensitive Organic Silver Salt Particles> Here, non-photosensitive organic silver salt particles used in the photothermographic material of the present invention will be described. In the present invention, the non-photosensitive organic silver salt particles have a silver behenate content of 90 mol% or more and 100 mol% or less. The non-photosensitive organic silver salt particles (hereinafter may be simply referred to as “organic silver salt”) according to the present invention are relatively stable to light, but are exposed to a photocatalyst (photosensitive silver halide). And a silver salt that forms a silver image when heated to 80 ° C. or higher in the presence of a reducing agent. The organic silver salt may be any organic substance including a source capable of reducing silver ions. Such non-photosensitive organic silver salts are described in JP-A-06-130543, JP-A-08-314078,
Nos. 9-127643 and 10-62899, paragraphs 0048 to 0049, JP-A-10-94074 and 1
0-94075, European Patent Publication No. 0803764A1
No. 18, page 24 to page 19, line 37, EP-A-0 962 812 A1, EP 100493.
0A2, JP-A-11-34991, JP-A-2000
-7683, 2000-72711, 2000
Nos. 112057 and 2000-155383. The non-photosensitive organic silver salt of the present invention is preferably a silver salt of an organic acid, particularly a silver salt of a long-chain aliphatic carboxylic acid (having 10 to 30 carbon atoms, preferably 15 to 28 carbon atoms). Preferred examples of the salt include silver behenate, silver arachidate, silver stearate, silver oleate,
Examples include silver laurate, silver caproate, silver myristate, silver palmitate, and mixtures thereof. The present invention is characterized in that the content of silver behenate in the non-photosensitive organic silver salt particles is from 90 mol% to 100%, thereby having a low Dmin, high sensitivity and excellent image storability. Preferred in that an organic silver salt can be obtained,
It is more preferably from 94 mol% to 100%, particularly preferably from 97 mol% to 100%. In the present invention, the content of silver stearate in the non-photosensitive organic silver salt particles is preferably 1 mol% or less, and the equivalent sphere diameter is preferably 0.05 μm or more and 1 μm or less. The stearic acid content is 1
% Or less, a silver salt of an organic acid having a low Dmin, high sensitivity and excellent image storability can be obtained. The stearic acid content is preferably 0.5 mol% or less,
It is particularly preferred that they are not substantially contained. When the sphere equivalent diameter is 0.05 μm or more and 1 μm or less, aggregation does not easily occur in the photosensitive material, and the image storability is improved. The equivalent spherical diameter is preferably 0.1 μm or more and 1 μm or less. In the present invention, the method for measuring the equivalent sphere diameter is obtained by directly photographing a sample using an electron microscope and then performing image processing on the negative.

Further, when silver arachidate is contained as a silver salt of an organic acid, the content of silver arachidate is not more than 6 mol%, so that a low Dmin is obtained and silver of an organic acid excellent in image storability is obtained. It is preferable in terms of obtaining a salt, and more preferably 3 mol% or less.

In the photothermographic material of the present invention, the non-photosensitive organic silver salt particles are preferably scaly particles, more preferably scaly particles having an aspect ratio of 1 or more and 9 or less. In the present specification, the flaky organic silver salt is defined as follows. Observe the organic acid silver salt with an electron microscope, approximate the shape of the organic acid silver salt particles to a rectangular parallelepiped,
When the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (c may be the same as b), the shorter numerical values a and b are calculated, and x is calculated as follows. Ask for. x = b / a y = c / b

As described above, x and y are obtained for about 200 particles, and when the average value x (average) is obtained, 3
Those satisfying the relationship of 0 ≧ x (average) ≧ 1.5 are regarded as scaly. Preferably, 30 ≧ x (average) ≧ 1.5, and more preferably, 20 ≧ x (average) ≧ 2.0. Incidentally, the needle shape is 1 ≦ x (average) <1.5. The average value y (average) is defined as the aspect ratio. The aspect ratio of the flaky particles is preferably 1 or more and 9 or less, more preferably 1 or more and 6 or less, and even more preferably 1 or more and 3 or less.

In the scaly particles, a can be regarded as a thickness of a tabular particle having a principal plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.23 μm or less, more preferably 0.1 μm or more and 0.20 μm or less.

In the scaly particles, the spherical equivalent diameter / a of the particles is defined as an aspect ratio. The aspect ratio of the flaky particles is preferably from 1.1 to 30 from the viewpoint that aggregation in the light-sensitive material hardly occurs and image storability is improved.
It is preferably not more than 1.1, more preferably not less than 1.1 and not more than 15.

The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion refers to a method of determining the standard deviation of the volume-weighted average diameter of the organic silver salt, and the percentage (coefficient of variation) of the value divided by the volume-weighted average diameter is preferably 100% or less, more preferably 80% or less, and furthermore Preferably 50%
It is as follows. As a measuring method, for example, an organic silver salt dispersed in a liquid is irradiated with a laser beam, and an autocorrelation function with respect to a time change of fluctuation of the scattered light is obtained from a particle size (volume weighted average diameter) obtained. be able to.

-Preparation of Non-Photosensitive Organic Silver Salt Particles- The non-photosensitive organic silver salt particles in the present invention are preferably prepared at a reaction temperature of 60 ° C. or lower from the viewpoint of preparing particles having a low Dmin. . The temperature of a chemical to be added, for example, an organic acid alkali metal aqueous solution may be higher than 60 ° C., but the temperature of the reaction bath to which the reaction solution is added is preferably 60 ° C. or lower. Furthermore, it is preferable that it is 50 degrees C or less, and it is especially preferable that it is 40 degrees C or less.

The non-photosensitive organic silver salt particles in the present invention are:
It is prepared by reacting a solution containing silver ions such as silver nitrate with an organic acid alkali metal salt solution or suspension. It is preferably carried out simultaneously with the addition to the suspension. Examples of the addition method include a method of adding the solution to the liquid surface of the reaction bath, a method of adding the solution to the solution, and a method of adding the solution into a closed mixing means described later, and any method may be used.

An example of a method for preparing the composition by adding it into a closed mixing means is shown below, but the present invention is not limited to this. FIG. 1 shows an embodiment of an apparatus for producing a non-photosensitive organic silver salt used in the present invention. In FIGS. 11 and 12, silver ion-containing solution (for example, silver nitrate aqueous solution) and organic alkali metal salt solution are stored at a predetermined temperature, respectively. 13
And 14 are flow meters for measuring the flow rates when these solutions are added to the sealed and liquid-filled mixing device 18 via the pumps 15 and 16. In this embodiment, a pump 17 for supplying the prepared organic silver salt dispersion to the mixing device 18 again as a third component is provided. The liquid that has been reacted in the mixing device 18 is supplied to the heat exchanger 1
9 and quickly cooled. The pH of the silver ion-containing solution (for example, an aqueous solution of silver nitrate) used in the present invention is preferably pH 1 or more and 6 or less, more preferably pH 1.5 or more and 4 or less. Further, acids and alkalis can be added for pH adjustment. The type of acid and alkali is not particularly limited.

The organic silver salt in the present invention may be aged by raising the reaction temperature after the addition of the silver ion-containing solution (for example, silver nitrate aqueous solution) and / or the organic acid alkali metal salt solution is completed. The aging in the present invention is considered to be different from the reaction temperature described above. During ripening, addition of silver nitrate and organic acid alkali metal salt solution or suspension is not performed at all. The aging is preferably performed at a reaction temperature of + 1 ° C or more and + 20 ° C or less, more preferably + 1 ° C or more and + 10 ° C or less. The aging time is preferably determined by trial and error.

In the preparation of the organic silver salt according to the present invention,
The addition of the organic acid alkali metal salt solution may be carried out in two or more divided and six or less divided portions. Here, various functions can be imparted to the particles by dividing and adding, for example, an addition for improving the photographic performance and an addition for changing the hydrophilicity of the surface. The number of divided additions is preferably 2 or more and 4 or less. Here, since the organic acid salt is solidified unless the temperature is high, it is necessary to consider, for example, having a plurality of addition lines for dividing or devising a circulating method or the like when dividing and adding.

In the preparation of the organic silver salt according to the present invention,
It is preferable that 0.5 mol% or more and 30 mol% or less of the total number of moles of the organic acid alkali metal salt solution be added alone after the addition of the silver ion-containing solution is completed. Preferably 3
It is preferred that at least 20 mol% be added alone. This addition is preferably devoted to one divided addition. This addition may be made in the closed mixing means or in the reaction tank, but is preferably added to the reaction tank. By performing this addition, the hydrophilicity of the surface of the particles can be increased, and as a result, the film forming property of the light-sensitive material is improved, and the peeling of the film is improved.

The silver ion concentration of the silver ion-containing solution (for example, an aqueous silver nitrate solution) used in the present invention is arbitrarily determined, and the molar concentration is 0.03 mol / L or more and 6.5 m or more.
ol / L or less, preferably 0.1 mol / L or more and 5 mo
1 / L or less is more preferable. In the practice of the present invention, in order to form non-photosensitive organic silver salt particles, at least one of a silver ion-containing solution, an organic acid alkali metal salt solution or suspension, and a solution previously prepared in a reaction field is required. Preferably, the alkali metal salt of the organic acid does not contain a string-like aggregate or micelle, but contains an organic solvent in an amount capable of forming a substantially transparent solution. The solution may be an organic solvent alone, but is preferably a mixed solution with water. As the organic solvent used in the present invention, the type thereof is not particularly limited as long as it has water-soluble properties described above, but those that interfere with photographic performance are not preferred, and alcohols and acetone that can be mixed with water are preferred, Tertiary alcohols having 4 to 6 carbon atoms are more preferred.

The alkali metal of the alkali metal salt of the organic acid used in the present invention is preferably Na or K.
The alkali metal salt of an organic acid is prepared by adding NaOH or KOH to an organic acid. At this time, it is preferable that the amount of the alkali is made equal to or less than the equivalent of the organic acid so that the unreacted organic acid remains. In this case, the amount of the residual organic acid is 3 mol% or more and 50 mol% or less, preferably 3 mol% or more and 30 mol% or less based on the total organic acid. Alternatively, after the alkali is added in a desired amount or more, an acid such as nitric acid or sulfuric acid may be added to neutralize the excess alkali. Further, the silver ion-containing solution and the organic acid alkali metal salt solution used in the present invention, or the solution in a closed mixing vessel to which both solutions are added, may be, for example, a compound represented by the general formula (1) of JP-A-62-65035. Compounds such as those described above, and water-soluble group-containing N-heterocyclic compounds as described in JP-A-62-150240;
Inorganic peroxides as described in JP-A-101019.
A sulfur compound as described in JP-A-51-78319, a disulfide compound and hydrogen peroxide as described in JP-A-57-643 can be added.

In the organic acid alkali metal salt solution used in the present invention, the amount of the organic solvent is preferably 3% or more and 70% or less, and more preferably 5% or more as a solvent volume with respect to the volume of water.
0% or less is more preferable. At this time, since the optimum solvent volume changes depending on the reaction temperature, the optimum amount can be determined by trial and error. The concentration of the alkali metal salt of the organic acid used in the present invention is 5 wt% or more and 50 w
t% or less, preferably 7 wt% or more and 45 wt% or less, and more preferably 10 wt% or more and 40 wt% or less.

The temperature of the tertiary alcohol aqueous solution of the organic acid alkali metal salt to be added in the closed mixing means or to the reaction vessel is maintained at a temperature necessary to avoid the crystallization and solidification of the organic acid alkali metal salt. 50 ° C or higher for the purpose 9
It is preferably 0 ° C or lower, more preferably 60 ° C or higher and 85 ° C or lower, most preferably 65 ° C or higher and 85 ° C or lower. Further, in order to control the temperature of the reaction to be constant, it is preferable that the temperature is controlled to be constant at a certain temperature selected from the above range.

Thus, the rate at which the tertiary alcohol aqueous solution of the alkali metal salt of the organic acid at a high temperature is rapidly cooled in the closed mixing means and precipitates in the form of microcrystals, and the rate at which the organic silver salt is reacted with the silver ion-containing solution are reduced. Preferably, the crystal form, crystal size, and crystal size distribution of the organic silver salt can be preferably controlled. At the same time, the performance as a heat developing material, especially as a heat developing photosensitive material, can be further improved.

A solvent may be contained in the reaction vessel in advance, and water is preferably used as a solvent to be put in advance, but a mixed solvent with the tertiary alcohol is also preferably used.

An aqueous medium-soluble dispersing aid can be added to the tertiary alcohol aqueous solution of the organic acid alkali metal salt, the silver ion-containing solution, or the reaction solution. Any dispersing agent may be used as long as it can disperse the formed organic silver salt. Specific examples are in accordance with the description of the organic silver salt dispersing agent described below.

In the method for preparing an organic silver salt, it is preferable to perform a desalting / dehydrating step after the formation of the silver salt. The method is not particularly limited, and known and commonly used means can be used.
For example, a known filtration method such as centrifugal filtration, suction filtration, ultrafiltration, floc-forming water washing by a coagulation method, and the like, and supernatant removal by centrifugal sedimentation and the like are preferably used. Desalination
Dehydration may be performed once or plural times. The addition and removal of water may be performed continuously or individually. In the desalination / dehydration, the conductivity of the finally dehydrated water is preferably 300 μS / cm or less, more preferably 10 μS / cm or less.
The treatment is performed so as to be 0 μS / cm or less, and most preferably 60 μS / cm or less. The lower limit of the conductivity in this case is not particularly limited, but is usually about 5 μS / cm.

As the ultrafiltration method, for example, a method used for desalting / concentrating a silver halide emulsion can be applied.
Research Disclosur
e) No. 10 208 (1972), No. 13 122 (1975) and No. 16 351
(1977). The pressure difference and flow rate that are important as operating conditions can be selected with reference to the characteristic curve described in “Handbook of Membrane Utilization Technology” written by Haruhiko Oya, Koshobo Publishing (1978), p. 275. In treating, it is necessary to find optimal conditions for suppressing aggregation and fogging of particles. In addition, in the method of replenishing the solvent that is lost due to membrane permeation, there are a constant volume type in which the solvent is continuously added and a batch type in which the solvent is added intermittently. Equations are preferred.

As the solvent to be replenished in this way, pure water obtained by ion exchange or distillation is used, but a pH adjuster or the like may be mixed in the pure water in order to keep the pH at a target value. Alternatively, it may be added directly to the organic silver salt dispersion.

The ultrafiltration membrane is a flat plate type, a spiral type, a cylindrical type, a hollow fiber type already incorporated as a module,
Hollow fiber type is commercially available from Asahi Kasei Co., Ltd., Daicel Chemical Co., Ltd., Toray Co., Ltd., Nitto Denko Corporation, etc., but from the viewpoint of total membrane area and cleanability, spiral type or hollow fiber type Is preferred. Further, the molecular weight cutoff as an index of the threshold value of the component that can pass through the membrane is preferably 1/5 or less of the molecular weight of the polymer dispersant used.

In the desalting by ultrafiltration in the present invention, it is preferable to disperse the liquid before the treatment so that the particle size is about twice as large as the deposition weighted average of the final particle size. Dispersing means, described later, high-pressure homogenizer,
Any method such as a microfluidizer may be used.

It is preferable to keep the liquid temperature low after the particle formation until the desalting operation proceeds. This is because, in a state where the organic solvent used for dissolving the alkali metal salt of the organic acid has penetrated into the generated organic silver salt particles, the shearing field when passing the liquid-passing operation or the ultrafiltration membrane and This is because silver nuclei are easily generated by the pressure field. For this reason, in the present invention, the ultrafiltration operation is performed while maintaining the temperature of the organic silver salt particle dispersion at 1 to 30 ° C, preferably 5 to 25 ° C.

Further, in order to improve the coated surface condition of the heat-developable material, particularly, the heat-developable photosensitive material, a desalted or dehydrated organic silver salt is added with a dispersant and dispersed to form a fine dispersion. Is preferred.

Known methods and the like can be applied to the production of the organic silver salt used in the present invention and its dispersion method. For example, the above-mentioned JP-A-8-234358 and JP-A-10-6
No. 2899, European Patent Publication No. 0803763A1, European Patent Publication No. 0962812A1, JP-A-11-349
No. 591, JP-A-2000-7683 and 2000-7
2711, 2000-53682, 2000-
No. 75437, 2000-86669, 2000
143578, 2000-178278, 2
000-256254, Japanese Patent Application No. 11-348.
No. 228-30, No. 11-203413, No. 11-1
No. 15457, No. 11-180369, No. 11-29
No. 7964, No. 11-157838, No. 11-202
08-81, Japanese Patent Application No. 2000-90093, and 2000-90093
195621, 2000-191226, 20
No. 00-213813, No. 2000-214155,
Reference can be made to the respective specifications and the like of JP-A-2000-191226.

The method of dispersing the organic silver salt into fine particles can be carried out by a known fine-graining means (for example, a high-speed mixer, a homogenizer, a high-speed impact mill, a Banbury mixer, a homomixer, a kneader, a ball mill, a vibration ball mill) in the presence of a dispersing agent. , A planetary ball mill, an attritor, a sand mill, a bead mill, a colloid mill, a jet mill, a roller mill, a tron mill, and a high-speed stone mill).

In order to obtain a uniform solid dispersion of fatty silver salt having a high S / N ratio, a small particle size and no aggregation, the organic silver salt particles serving as the image forming medium must be in a range which does not cause damage or high temperature. It is preferable to apply a large force uniformly. For this purpose, a dispersion method in which a dispersion comprising an organic silver salt and a dispersant solution is converted into a high-speed stream and then the pressure is reduced is preferred. In this case, the dispersion medium may be any solvent as long as it functions as a dispersion aid, but is preferably water alone, and may contain an organic solvent if it is 20 wt% or less. Further, when a photosensitive silver salt coexists at the time of dispersion, fog increases and the sensitivity is remarkably reduced. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. In the present invention, the amount of the photosensitive silver salt in the dispersion liquid to be dispersed is 0.1 mol% or less based on 1 mol of the organic silver salt in the liquid,
It is preferable not to add a photosensitive silver salt.

For a dispersion apparatus and a technique used for performing the above-described redispersion method, see, for example, "Dispersion Rheology and Dispersion Technique" (by Toshio Kajiuchi and Hiroki Usui, 1991, Shinzansha Publishing). Co., Ltd., p357-40
3), “Progress in Chemical Engineering Vol. 24,” edited by The Society of Chemical Engineers, Tokai Branch, 1990, Maki Shoten, pp. 184-18
5), JP-A-59-49832, U.S. Pat.
No. 54, JP-A-8-137044, JP-A-8-238
848, JP-A-2-261525, JP-A-1-94
No. 933, etc., the redispersion method of the present invention is based on a method in which at least a dispersion containing an organic silver salt is pressurized by a high-pressure pump or the like and fed into a pipe, and then passed through a narrow slit provided in the pipe. After that, a sharp drop in pressure is caused in the dispersion liquid to perform fine dispersion.

As for the high-pressure homogenizer, generally, (a) “shearing force” generated when the dispersoid passes through a narrow gap (about 75 μm to 350 μm) at high pressure and high speed;
It is thought that the cavitation force due to the subsequent pressure drop is further increased without changing the impact force generated when liquid-liquid collision or wall collision occurs in a narrow space with high pressure, and uniform and efficient dispersion is performed. ing. An example of this type of dispersing device is a Gaulin homogenizer.In this device, the liquid to be dispersed sent at high pressure is converted into a high-speed flow through a narrow gap on the cylindrical surface, and the force is applied to the surrounding wall by the force. The particles collide and are emulsified and dispersed by the impact force. Examples of the liquid-liquid collision include a Y-type chamber of a microfluidizer, a spherical chamber using a spherical check valve as described in Japanese Patent Application Laid-Open No. 8-106364, and the like. Examples include a Z-type chamber of a microfluidizer. The working pressure is generally in the range of 100 to 600 kg / cm ² (1 to 6 MPa), and the flow rate is in the range of several m to 30 m / sec. Some ideas have been devised. Typical examples of such an apparatus include a Gorin homogenizer, a microfluidizer manufactured by Microfluidics International Corporation, a microfluidizer manufactured by Mizuho Industry Co., Ltd., and a nanomizer manufactured by Tokushu Kika Kogyo Co., Ltd. . JP-A-8-238848, 8
No. 103642 and US Pat. No. 4,533,254.

The organic silver salt can be dispersed to a desired particle size by adjusting the flow rate, the differential pressure at the time of pressure drop, and the number of treatments, but from the viewpoint of photographic characteristics and particle size, the flow rate is 200 to 600 m / m. Second, the differential pressure at the time of pressure drop is 900-3
000 kg / cm ² (9 to 30 MPa) is preferable, and the flow rate is 300 to 600 m / sec, and the differential pressure at the time of pressure drop is 1500 to 3000 kg / cm ² (15 to 30 MPa).
More preferably, it is within the range of a). The number of times of the distributed processing can be selected as needed. Usually, the range of 1 to 10 times is selected, but from the viewpoint of productivity, about 1 to 3 times is selected. Elevating such dispersions under high pressure is not good for dispersibility
At a high temperature exceeding 90 ° C., the particle size tends to increase and fog tends to increase. Therefore, the step before the conversion into the high-pressure, high-speed flow, the step after the pressure is reduced, or both of these steps includes a cooling device, and the temperature of such dispersion is in the range of 5 to 90 ° C. by the cooling step. It is preferably maintained in the range of 5 to 80 ° C, more preferably in the range of 5 to 65 ° C. In particular, 1500-3000 kg / cm ² (15-
At the time of high pressure dispersion in the range of 30 MPa), it is effective to install the cooling device described above. As the cooling device, a device using a static mixer for a double tube or a triple tube, a multi-tube heat exchanger, a coiled tube heat exchanger, or the like can be appropriately selected according to the required heat exchange amount. In addition, in order to increase the efficiency of heat exchange, it is only necessary to select a suitable one such as a pipe thickness, a wall thickness and a material in consideration of a working pressure. As the refrigerant used for the cooler, a refrigerant such as well water at 20 ° C., cold water at 5 to 10 ° C. treated with a refrigerator, and ethylene glycol / water at −30 ° C. as necessary are used, based on the heat exchange amount. can do.

When the organic silver salt is formed into solid fine particles using a dispersant, for example, polyacrylic acid, a copolymer of acrylic acid, a maleic acid copolymer, a maleic acid monoester copolymer, and acryloylmethyl Synthetic anionic polymers such as propanesulfonic acid copolymer, semi-synthetic anionic polymers such as carboxymethyl starch and carboxymethyl cellulose, anionic polymers such as alginic acid and pectic acid, JP-A-52-92716, WO88 /
No. 04794, etc., anionic surfactants, compounds described in Japanese Patent Application No. 7-350753, or known anionic, nonionic, cationic surfactants and other polyvinyl alcohols, polyvinylpyrrolidone, carboxymethylcellulose, Known polymers such as hydroxypropylcellulose and hydroxypropylmethylcellulose, or naturally occurring polymer compounds such as gelatin can be appropriately selected and used. When a solvent is used as the dispersion medium, polyvinyl butyral, butylethyl cellulose, methacrylate copolymer, maleic anhydride ester copolymer, polystyrene, butadiene-styrene copolymer and the like are preferably used.

It is a general method that the dispersing aid is mixed with the organic silver salt powder or the organic silver salt in a wet cake state before the dispersion, and then sent as a slurry to the dispersing machine. Heat treatment or treatment with a solvent may be performed in the combined state to obtain an organic silver salt powder or a wet cake. Before and after dispersion or during dispersion, p.
H control may be performed.

In addition to mechanical dispersion, the particles may be coarsely dispersed in a solvent by controlling the pH, and then finely divided by changing the pH in the presence of a dispersing agent. At this time, a fatty acid solvent may be used as a solvent used for the coarse dispersion.

It is to be noted that, when a photosensitive silver salt is present in the dispersion of the organic silver salt, fog increases and the sensitivity is remarkably reduced. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained during the dispersion. In the present invention, the amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is 0.1 to 1 mol of the organic silver salt in the liquid.
The content is 1 mol% or less, and the photosensitive silver salt is not positively added.

In the present invention, it is possible to produce a photosensitive material by mixing an aqueous dispersion of an organic silver salt and an aqueous dispersion of a photosensitive silver salt, but the mixing ratio of the organic silver salt to the photosensitive silver salt depends on the purpose. You can choose, but the ratio of photosensitive silver salt to organic silver salt is 1
~ 30 mol% is preferable, and further 3 ~ 20 mol%,
Particularly, a range of 5 to 15 mol% is preferable. 2 when mixing
Mixing an aqueous dispersion of at least one kind of organic silver salt with an aqueous dispersion of at least two kinds of photosensitive silver salt is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present invention can be used in a desired amount, but the silver amount is preferably 0.1 to 5 g / m ² ,
g / m ² is more preferred.

<Reducing Agent> The photothermographic material of the present invention comprises, on one surface of a support, at least one photosensitive silver halide, a reducing agent for silver ions, a binder, and a non-photosensitive organic compound. A silver salt particle, wherein the non-photosensitive organic silver salt particle has a silver behenate content of 90 mol% or more and 100 mol% or less, and the reducing agent is a compound represented by the following general formula (I). It is characterized by the following.

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In the general formula (I), R ¹¹ and R ¹¹ ′ each independently represent 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 is -S- group or CHR
Represents a ¹³ -group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring.

In the photothermographic material of the present invention, when the content of silver behenate in the non-photosensitive organic silver salt particles is 90 mol% or more and 100 mol% or less, Dmin is low, and heat is excellent in image storability. By using the compound represented by the formula (I) of the present invention as a reducing agent for an organic silver salt, a developing photosensitive material can be obtained, the developing activity is high, the development is not delayed, and the non-image area can be obtained. And a high-sensitivity photothermographic material having less fog can be obtained.

The general formula (I) will be described in detail. 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 may be an aryl group, a hydroxy group, or 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.

R ¹² and R ¹² ′ each independently represent a hydrogen atom,
X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. Preferable examples of the 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.

L represents a —S— group or a CHR ¹³ — group.
R ¹³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and the alkyl group may have a substituent. R ¹³
Specific examples of the unsubstituted alkyl group of methyl, ethyl, propyl, butyl, heptyl, undecyl, isopropyl, 1-ethylpentyl, 2,
Preferable examples include a 4,4-trimethylpentyl group.
Examples of the substituent of the alkyl group, the same as the substituent of R ^11, a halogen atom, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acylamino group, a sulfonamido group, a sulfonyl group, a phosphoryl group,
Preferable examples include an oxycarbonyl group, a carbamoyl group, and a sulfamoyl group.

R ¹¹ and R ¹¹ ′ each have 3 to 3 carbon atoms.
Preferred are 15 secondary or tertiary alkyl groups, specifically, isopropyl, isobutyl, t-butyl, t-butyl, and the like.
- amyl, t-octyl group, a cyclohexyl group, a cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like are suitably exemplified, wherein R ¹¹ and R ¹¹ 'is 3 to 8 carbon atoms A secondary or tertiary alkyl group is more preferred, and among them, a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferred, and a t-butyl group is most preferred.

R ¹² and R ¹² ′ are preferably an alkyl group, more preferably an alkyl group having 1 to 20 carbon atoms. Specifically, methyl, ethyl, propyl, butyl, isopropyl, t -Butyl group, t-amyl group,
Preferable examples include a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a methoxymethyl group, and a methoxyethyl group, and more preferable examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a 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.

The above L is preferably a —CHR ¹³ — group. R ¹³ is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group,
A preferred example is a 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 1 to 5 carbon atoms, more preferably a methyl group, an ethyl group, and a propyl group, and most preferably a methyl group and an ethyl group. When R ¹³ is a primary or secondary alkyl group having 1 to 5 carbon atoms, a methyl group is preferred as R ¹² and R ¹² ′. As the primary or secondary alkyl group having 1 to 5 carbon atoms of R ¹³ , a methyl group, an ethyl group, a propyl group, and an isopropyl group are more preferable, and a methyl group, an ethyl group, and a propyl group are more preferable. When R ¹¹ , R ¹¹ ′, R ¹² and R ¹² ′ are all methyl groups, R ¹³ is preferably a secondary alkyl group. In this case, the secondary alkyl group of R ¹³ is An isopropyl group, an isobutyl group and a 1-ethylpentyl group are preferred, and an isopropyl group is particularly preferred.

In the compound represented by formula (I), R ¹¹ and R ¹¹ ′ are each independently a secondary or tertiary alkyl group having 3 to 8 carbon atoms, and R ¹² and R ¹² ′ Are each independently an alkyl group; L is a —CHR ¹³ — group;
¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
Those in which ¹ and X ¹ ′ are hydrogen atoms are particularly preferred.

Hereinafter, the reducing agent of the present invention represented by the general formula (I)
Specific examples of the compounds represented by (Exemplified compounds I-2 to 27)
However, the present invention is not limited to these.

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In the present invention, as the reducing agent for the organic silver salt, another reducing agent may be used in combination with the compound represented by formula (I). As a reducing agent for an organic silver salt that can be used in combination, any substance (preferably an organic substance) that can reduce silver ions to metallic silver may be used.
Such reducing agents are described in paragraphs 0043 to 0045 of JP-A-11-65021 and European Patent Publication No. 08037.
Page 7 line 34 to page 18 twelfth of 64A1
Listed on the line. Among them, hindered phenols reducing agents and bisphenols reducing agents are preferred.

In the present invention, the amount of the reducing agent represented by the general formula (I) is 0.01 to 5.0 g / m ^2.
And more preferably 0.1 to 3.0 g / m ² , preferably 5 to 50 mol%, and more preferably 1 to 50 mol% with respect to 1 mol of silver on the surface having the image forming layer.
More preferably, the content is 0 to 40 mol%. The reducing agent is preferably contained in the image forming layer.

In the present invention, the reducing agent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form and a solid fine particle dispersion form, and may be contained in the photosensitive material. Well-known emulsification dispersion methods include oils such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, and dissolution using an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. A method for producing the same is given.

In the solid fine particle dispersion method, a powder of a reducing agent is dispersed in a suitable solvent such as water by a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill, or ultrasonic waves to obtain a solid dispersion. Is produced. In this case, a protective colloid (for example, polyvinyl alcohol) and 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).

In the photothermographic material of the present invention, a phenol derivative represented by the formula (A) described in Japanese Patent Application No. 11-73951 is preferably used as a development accelerator.

<Hydrogen Bonding Compound> The photothermographic material of the present invention preferably contains a hydrogen bonding compound on one surface of the support. As the hydrogen bonding compound, since the compound represented by the general formula (I) of the present invention is a bisphenol reducing agent having an aromatic hydroxyl group (-OH), a hydrogen bond with these groups is formed. It is preferable to use a non-reducing compound having a group that can be formed. Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. No. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (provided that they have no> NH group and are blocked like> N-Ra (Ra is a substituent other than H)), and a urethane group. (However, it has no> NH group and is blocked like> N-Ra (Ra is a substituent other than H)), a ureido group (where> N-
It has no H group and is blocked as in> N-Ra (Ra is a substituent other than H). ).
In the present invention, a particularly preferred hydrogen bonding compound is a compound represented by the following general formula (II).

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In the general formula (II), R ²¹ , R ²² and R ²³ each independently represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group. It may be unsubstituted or have a substituent. In addition, any two of R ²¹ , R ²² and R ²³
One may combine with each other to form a ring.

When R ²¹ , R ²² and 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, Sulfonamide group, acyloxy group, oxycarbonyl group, carbamoyl group, sulfamoyl group, sulfonyl group, phosphoryl group and the like, among which alkyl group or aryl group is preferable, for example, methyl group, ethyl group, isopropyl group, t -Butyl group, t-octyl group, phenyl group,
A 4-alkoxyphenyl group, a 4-acyloxyphenyl group and the like are more preferred.

As the alkyl group represented by R ²¹ , R ²² and R ²³ , specifically, methyl, ethyl, butyl, octyl, dodecyl, isopropyl, t-
Butyl group, t-amyl group, t-octyl group, cyclohexyl group, 1-methylcyclohexyl group, benzyl group, phenethyl group, 2-phenoxypropyl group, and the like,
Among them, a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a phenethyl group, and a 2-phenoxypropyl group are preferred. Examples of the aryl group represented by R ²¹ , R ²² and R ²³ include a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group,
t-octylphenyl group, 4-anisidyl group, 3,5-
Dichlorophenyl group and the like. Among them, phenyl group, cresyl group, xylyl group, naphthyl group, 4-t
A -butylphenyl group is preferred, and a 4-t-butylphenyl group is particularly preferred. Examples of the alkoxy group represented by R ²¹ , R ²² and R ²³ include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, a 2-ethylhexyloxy group, a 3,5,5-trimethylhexyloxy group, a dodecyloxy group Groups, cyclohexyloxy group, 4-methylcyclohexyloxy group, benzyloxy group and the like. Among them, cyclohexyloxy group is preferable.

The aryloxy groups represented by R ²¹ , R ²² and R ²³ include phenoxy, cresyloxy, isopropylphenoxy, 4-t-butylphenoxy, naphthoxy, biphenyloxy and the like. Of these, a phenoxy group is preferred. R ²¹ , R ²²
And examples of the amino groups denoted by R ^23, dimethylamino group, diethylamino group, dibutylamino group, dioctylamino group, N- methyl -N- hexylamino group, dicyclohexylamino group, diphenylamino group, N- methyl - Examples thereof include an N-phenylamino group, and among them, a dimethylamino group, a dicyclohexylamino group, and a diphenylamino group are preferable.

Among the groups represented by R ²¹ , R ²² and R ²³ , an alkyl group, an aryl group, an alkoxy group and an aryloxy group are more preferred. From the viewpoint of the effect of the present invention, R
It is further preferred that at least one of ²¹ , ^22, and ²³ is an alkyl group or an aryl group, and it is particularly preferred that at least two of them are an alkyl group or an aryl group. In addition, it is preferable that R ²¹ , R ²² and R ²³ are the same group from the viewpoint that they can be obtained at low cost.

Hereinafter, the general formula (II) used in the present invention will be described.
Specific examples (II-1 to 17) of the hydrogen bonding compound including the compound represented by are shown below, but the present invention is not limited thereto.

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Specific examples of the hydrogen bonding compound are described in Japanese Patent Application Nos. 2000-192191 and 2000-1948 in addition to those described above.
No. 11 may be mentioned. The compound represented by the general formula (II) used in the present invention may be contained in a coating solution in the form of a solution, an emulsified dispersion, or a solid-dispersed fine particle dispersion in the same manner as the reducing agent, and used in a photosensitive material. Can be. The compound forms a hydrogen-bonding complex with a compound having a phenolic hydroxyl group and an amino group in a solution state, and depending on the combination of the reducing agent and the compound represented by the general formula (II), the complex As a crystalline state. It is particularly preferable to use the crystal powder isolated in this manner as a solid dispersion fine particle dispersion in order to obtain stable performance. Further, mixing the reducing agent and the compound represented by the general formula (II) in powder,
A method of forming a complex at the time of dispersion by a sand grinder mill or the like using an appropriate dispersant can also be preferably used. The compound of the general formula (II) is a reducing agent represented by the general formula (I) of the present invention (when other reducing agents are used in combination, the reducing agent represented by the general formula (I) 1 to 200 mol% based on the sum of the reducing agent used in combination)
It is preferable to use in the range of, more preferably, 10
To 150 mol%, more preferably 30 to 100 mol%.
Mol% range.

<Photosensitive Silver Halide> The photosensitive silver halide used in the photothermographic material of the present invention is not particularly limited as a halogen composition, and may be silver chloride, silver chlorobromide, silver bromide,
Silver iodobromide and silver iodochlorobromide can be used. Among them, silver bromide and silver iodobromide are preferred. The distribution of the halogen composition in the grains may be uniform, the halogen composition may be changed stepwise, or may be changed continuously. Further, silver halide grains having a core / shell structure can be preferably used. Preferred as the structure is a 2- to 5-fold structure,
More preferably, core / shell particles having a double or quadruple structure can be used. Further, a technique of localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

Methods for forming photosensitive silver halide are well known in the art and are described, for example, in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. Specifically, a method of preparing a photosensitive silver halide by adding a silver supply compound and a halogen supply compound to gelatin or another polymer solution, and then mixing the organic silver salt with an organic silver salt is used. Used. Further, Japanese Unexamined Patent Publication No.
JP-A-119374 / paragraphs 0217 to 0224, Japanese Patent Application No. 11-98708, Japanese Patent Application No.
The method described in 000-42336 is also preferred.

The grain size of the photosensitive silver halide is preferably small for the purpose of suppressing white turbidity after image formation, and specifically, is preferably 0.20 μm or less.
01 μm or more and 0.15 μm or less are more preferable,
It is more preferably from 2 μm to 0.12 μm. In addition,
The grain size as used herein refers to a diameter when converted into a circular image having the same area as the projected area of a silver halide grain (in the case of a tabular grain, the projected area of a main plane).

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

In the present invention, the hexacyano metal complex is
Silver halide grains present on the outermost surface of the particles are preferred. Six
As the cyano metal complex, [Fe (CN)₆]^Four-, [F
e (CN)₆]^3-, [Ru (CN)₆]^Four-, [Os (C
N)₆]^Four-, [Co (CN)₆] ^3-, [Rh (CN)₆]
^3-, [Ir (CN)₆]^3-, [Cr (CN)₆]^3-,
[Re (CN)₆]^3-And the like. inside that
Also, in the present invention, a hexacyano Fe complex is preferable.

Since the hexacyano metal complex exists in the form of ions in an aqueous solution, the counter cation is not important.
Alkali metal ions such as sodium ion, potassium ion, rubidium ion, cesium ion and lithium ion, ammonium ions, alkylammonium ions (for example, tetramethylammonium ion) which are easily miscible with water and are suitable for the precipitation operation of silver halide emulsions , Tetraethylammonium ion, tetrapropylammonium ion, and tetra (n-butyl) ammonium ion).

The hexacyano metal complex may be mixed with a water-miscible organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides, etc.) in addition to water. Or gelatin and a mixture thereof.

The addition amount of the hexacyano metal complex is as follows.
The amount is preferably from 1 × 10 ⁻⁵ mol to 1 × 10 ⁻² mol per mol of silver, more preferably from 1 × 10 ⁻⁴ mol to 1 × 10 ⁻³ mol.

In order for the hexacyano metal complex to be present on the outermost surface of the silver halide grains, the addition of the hexacyano metal complex to an aqueous silver nitrate solution used for grain formation is followed by sulfur sensitization, selenium sensitization and tellurium sensitization. It is added directly before the completion of the charging step before the chemical sensitization step for performing noble metal sensitization such as chalcogen sensitization or gold sensitization, during the washing step, during the dispersion step, or before the chemical sensitization step. In order not to grow the silver halide fine grains, it is preferable to add the hexacyano metal complex immediately after the grain formation, and it is preferable to add the hexacyano metal complex before the completion of the charging step.

Incidentally, the addition of the hexacyano metal complex is 96% by mass of the total amount of silver nitrate added for forming grains.
May be started after the addition, more preferably after the addition of 98% by mass, and particularly preferably after the addition of 99% by mass.

When the hexacyano metal complex is added after the addition of the aqueous solution of silver nitrate immediately before the completion of grain formation, it can be adsorbed on the outermost surface of the silver halide grains, and most of them are hardly soluble in silver ions on the grain surface. Forms salt. Since the hexacyanoiron (II) silver salt is a salt that is less soluble than AgI, re-dissolution by fine particles can be prevented, and silver halide fine particles having a small particle size can be produced. .

In the present invention, the light-sensitive silver halide grains are selected from groups 8 to 8 of the periodic table (showing groups 1 to 18).
It may contain a Group 10 metal or metal complex.
Rhodium, ruthenium, and iridium are preferred as the metals of Groups 8 to 10 of the periodic table or the central metal of the metal complex. 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 per mol of silver. These heavy metals and metal complexes and their addition methods are described in JP-A-7-225.
449, JP-A-11-65021, paragraph number 0018
0024, JP-A-11-119374, paragraph number 02
27 to 0240.

Further, metal atoms (for example, [F] which can be contained in the photosensitive silver halide grains used in the present invention.
e (CN) ₆ ] ^4- ), the desalting method and the chemical sensitization method of the photosensitive silver halide emulsion are described in JP-A-11-84574, paragraphs 0046 to 0050 and JP-A-11-65021.
No. 0025-0031, JP-A-11-11
No. 9374, paragraphs 0242 to 0250.

As the gelatin contained in the photosensitive silver halide emulsion used in the present invention, various gelatins can be used. In order to maintain a good dispersion state of the photosensitive silver halide emulsion in the coating solution containing an organic silver salt, it is preferable to use 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 grain formation or at the time of dispersion after desalting, but are preferably used at the time of dispersion after desalting.

Sensitizing dyes applicable to the present invention are those capable of spectrally sensitizing silver halide grains in a desired wavelength region when adsorbed on photosensitive silver halide grains, and are suitable for the spectral characteristics of an exposure light source. Sensitizing dyes having spectral sensitivity can be advantageously selected. For sensitizing dye and addition method,
Paragraph Nos. 0103-0 of JP-A-11-65021
109, a compound represented by the general formula (II) in JP-A-10-186572, JP-A-11-11937.
4, the dye represented by formula (I) and the dye described in paragraph 5 of Example 5, U.S. Pat. Nos. 5,510,236 and 3,871,887 described in Example 5; No. 96131 and JP-A-59-48753, European Patent Publication No. 0803764.
A1 page 19, line 38 to page 20, page 35
Line, Japanese Patent Application No. 2000-86865, Japanese Patent Application No. 2000-10
2560 and Japanese Patent Application No. 2000-205399. These sensitizing dyes may be used alone or in combination of two or more. In the present invention, the timing of adding a sensitizing dye to a silver halide emulsion is as follows.
The period after the desalting step and before coating is preferable, and the period after desalting and before the start of chemical ripening is more preferable. The addition amount of the sensitizing dye in the present invention may be a desired amount according to the property of sensitivity and fogging, preferably 1 mol of silver halide per 10 ^-6 to 1 mol of the photosensitive layer, 10 ^{- 4} to
10 ^-1 mol is more preferred.

In the present invention, a supersensitizer can be used to improve the spectral sensitization efficiency. The supersensitizer used in the present invention includes European Patent Publication No. 587,33.
8, U.S. Pat. Nos. 3,877,943 and 4,872.
3,184, JP-A-5-341432, 11-1
Compounds described in JP-A Nos. 09547 and 10-111543 are exemplified.

The photosensitive silver halide grains in the present invention are preferably chemically sensitized by a sulfur sensitization method, a selenium sensitization method, or a tellurium sensitization method. As compounds preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method, known compounds, for example, JP-A-7-12876
Compounds described in JP-A No. 8 and the like can be used.
In particular, tellurium sensitization is preferable in the present invention, and compounds described in the literature described in paragraph No. 0030 of JP-A-11-65021, and compounds represented by general formulas (II), (III) and The compound represented by (IV) is more preferred.

In the present invention, chemical sensitization can be performed at any time after grain formation and before coating, and after desalting, (1) before spectral sensitization, (2) simultaneously with spectral sensitization, 3)
After spectral sensitization, there may be (4) just before coating. In particular, it is preferably performed after spectral sensitization. The amount of the sulfur, selenium and tellurium sensitizers used in the present invention varies depending on the silver halide grains used, the conditions of chemical ripening, etc., but is preferably 10 ^-8 to 10 ^-2 mol per mol of silver halide, preferably. Uses about 10 ^-7 to 10 ^-3 mol. The conditions for the chemical sensitization in the present invention are not particularly limited, but the pH is 5 to 8, the pAg is 6 to 11, and the temperature is about 40 to 95 ° C. A thiosulfonate compound may be added to the silver halide emulsion used in the present invention by the method described in EP-A-293,917.

The photosensitive silver halide emulsion used in the photothermographic material of the present invention may be of one kind or two or more kinds (for example, those having different average grain sizes, different halogen compositions, different crystal habits). And those having different conditions of chemical sensitization). The gradation can be adjusted by using a plurality of photosensitive silver halides having different sensitivities. The technology relating to these is disclosed in Japanese Patent Application Laid-Open No.
No. 41, No. 53-106125, No. 47-3929
Nos. 48-55730, 46-5187, 5
Nos. 0-73627 and 57-150841. The sensitivity difference was 0.1 for each emulsion.
It is preferable to have a difference of 2 logE or more.

The amount of photosensitive silver halide added was 1 m
Indicated by the amount of coated silver per ^{2, 0.03~0.6g} / m ²
It is preferably, more preferably from 0.07~0.4g / m ^2, and most preferably from 0.05 to 0.3 g / m ^2, relative to the organic silver salt 1 mole,
The photosensitive silver halide is preferably used in an amount of from 0.01 mol to 0.5 mol, more preferably from 0.02 mol to 0.3 mol.

Regarding the mixing method and the mixing conditions of the separately prepared photosensitive silver halide and organic silver salt, the prepared silver halide particles and organic silver salt were mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, and the like. There are a method of mixing with a vibration mill, a homogenizer, etc., and a method of preparing an organic silver salt by mixing photosensitive silver halide prepared at any timing during the preparation of the organic silver salt. There is no particular limitation as long as the effect of (1) fully appears. Mixing two or more aqueous dispersions of organic silver salts with two or more aqueous dispersions of photosensitive silver salts is a preferable method for adjusting photographic characteristics.

The preferred timing of adding the photosensitive silver halide of the present invention to the coating solution for the image forming layer is from 180 minutes to immediately before coating, preferably from 60 minutes to 10 seconds before coating.
The mixing method and mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, there is a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time, Harnby, M .; F. Edwar
ds, A.D. W. There is a method using a static mixer or the like described in Chapter 8 of Nienow, "Liquid Mixing Technology" translated by Koji Takahashi (Nikkan Kogyo Shimbun, 1989).

<Binder> In the photothermographic material of the present invention, the binder contained in the organic silver salt-containing layer may be any polymer. Suitable binders include transparent or translucent, generally colorless, natural resins and polymers and copolymers, synthetic resins and polymers and copolymers, and other film-forming media such as gelatins, rubbers, poly (vinyl alcohol) )
, Hydroxyethylcellulose, cellulose acetates, cellulose acetate butyrate, poly (vinylpyrrolidone), casein, starch, poly (acrylic acid), poly (methylmethacrylic acid), poly (vinyl chloride), poly (Methacrylic acid) s, 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 (urethane) s, phenoxy resins, poly (vinylidene chloride) s, poly (epoxides), poly (carbonates), poly (vinyl acetate) s, poly (olefins) , Cellulose esters, poly (amide)
And the like. The binder may be coated from water or an organic solvent or emulsion.

In the present invention, the glass transition temperature of the binder in the organic silver salt-containing layer is preferably from 10 ° C. to 80 ° C. (hereinafter sometimes referred to as a high Tg binder), and is from 20 ° C. to 70 ° C. More preferably, the temperature is 23 ° C. or more and 65 ° C. or less.

In this specification, Tg was calculated by the following equation. 1 / Tg = Σ (Xi / Tgi) Here, it is assumed that the polymer has copolymerized n monomer components from i = 1 to n. Xi is the weight fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer.
Where Σ is the sum of i = 1 to n. The homopolymer glass transition temperature (Tgi) of each monomer is Pol
ymer Handbook (3rd Edition
n) (J. Brandrup, EH Immerg)
ut (Wiley-Interscience, 19
89)) was adopted.

The polymer serving as a binder may be used alone or in combination of two or more as necessary. Further, those having a glass transition temperature of 20 ° C. or more and those having a glass transition temperature of less than 20 ° C. may be used in combination. When two or more polymers having different Tg are blended and used, the weight average Tg is preferably in the above range.

In the present invention, when the organic silver salt-containing layer is formed by coating using a coating solution in which 30% by mass or more of the solvent is water and drying, the binder of the organic silver salt-containing layer is further added. The performance is improved when it is soluble or dispersible in an aqueous solvent (aqueous solvent), particularly when it is composed of a polymer latex having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The most preferred form has an ionic conductivity of 2.5
mS / cm or less. As such a preparation method, a method of purifying using a separation functional membrane after polymer synthesis can be mentioned.

Here, the aqueous solvent in which the polymer as a binder is soluble or dispersible is water or 70% water.
It is a mixture of water-miscible organic solvents of not more than mass%. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethyl acetate; and dimethylformamide.

The term “aqueous solvent” is used herein even in the case where the polymer serving as the binder is not thermodynamically dissolved but exists in a so-called dispersed state.

The “equilibrium moisture content at 25 ° C. and 60% RH” refers to the weight W _{1 of the} polymer in a moisture-conditioning equilibrium in an atmosphere of 25 ° C. and 60% RH, and the weight W of the polymer in a completely dry state at 25 ° C. It can be expressed as follows using ₀ .
Equilibrium water content at 25 ° C. and 60% RH = ｛(W ₁ −W ₀ )
/ W ₀ ｝ × 100 (% by mass)

The definition and measurement method of the water content can be referred to, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by The Society of Polymer Science, Jinjinshokan).

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

In the present invention, the polymer serving as the binder is particularly preferably a polymer dispersible in an aqueous solvent. Examples of the dispersion state include a latex in which fine particles of a water-insoluble hydrophobic polymer are dispersed, and a dispersion in which polymer molecules are dispersed in a molecular state or in the form of micelles. The average particle size of the dispersed particles is preferably in the range of 1 to 50,000 nm, and 5 to 100 nm.
A range of about 0 nm is more preferable. There are no particular restrictions on the particle size distribution of the dispersed particles, and they may have a broad particle size distribution or a monodispersed particle size distribution.

In the present invention, preferred embodiments of the polymer dispersible in an aqueous solvent include acrylic polymers,
Hydrophobic properties such as poly (ester) s, rubbers (eg, SBR resin), poly (urethane) s, poly (vinyl chloride) s, poly (vinyl acetate) s, poly (vinylidene chloride) s, poly (olefins) A polymer can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers in which a single monomer is polymerized, or copolymers in which two or more types of monomers are polymerized. In the case of a copolymer, even a random copolymer,
It may be a block copolymer. The number average molecular weight of these polymers is preferably 5,000 to 1,000,000, more preferably 10,000 to 200,000.
If the molecular weight is too small, the mechanical strength of the silver halide emulsion layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

Preferred specific examples of the polymer latex include the following. In the description below, the raw material monomers are used, the numerical value in parentheses is% by mass, and the molecular weight is the number average molecular weight. When a polyfunctional monomer is used, the concept of molecular weight cannot be applied because a crosslinked structure is formed.
Tg represents a glass transition temperature.

Latex of P-1; -MMA (70) -EA (27) -MAA (3)-(molecular weight 37000) P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-latex (molecular weight 40
000) P-3; -St (50) -Bu (47) -MAA (3)-latex (crosslinkable) P-4; -St (68) -Bu (29) -AA (3)-latex (Crosslinking) P-5; -St (71) -Bu (26) -AA (3)-latex (Crosslinking, Tg24 ° C) P-6; -St (70) -Bu (27) -IA ( 3) -Latex (crosslinkable) P-7; -St (75) -Bu (24) -AA (1) -Latex (crosslinkable) P-8; -St (60) -Bu (35)- Latex of DVB (3) -MAA (2)-(crosslinkable) P-9; Latex of -St (70) -Bu (25) -DVB (2) -AA (3)-(crosslinkable) P-10 ; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (MW 80000) P-11; -VDC (85) -MMA (5) -EA ( 5) -MAA (5)-latex (molecular weight 67
000) P-12; -Et (90) -MAA (10)-latex (Mw 12000) P-13; -St (70) -2EHA (27) -AA (3) latex (Mw 130000) P- 14; -MMA (63) -EA (35)-AA (2) latex (molecular weight 33000) P-15; -St (70.5) -Bu (26.5) -AA (3)-latex (crosslinkable, Tg23
° C) P-16; -St (69.5) -Bu (27.5) -AA (3)-latex (crosslinkable, Tg20.
(5 ℃)

The abbreviations of 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;
C; vinyl chloride, AN; acrylonitrile, VDC; vinylidene chloride, Et; ethylene, IA; itaconic acid.

The polymer latex described above is commercially available, and the following polymers can be used. Examples of acrylic polymers include Sebian A-463.
5, 4718, 4601 (Daicel Chemical Industries, Ltd.)
Nipol Lx811, 814, 821, 82
Examples of poly (esters) such as 0, 857 (all manufactured by Zeon Corporation) are FINETEX ES65.
Examples of poly (urethane) s such as 0, 611, 675, and 850 (all manufactured by Dainippon Ink and Chemicals, Inc.), WD-size, and WMS (all manufactured by Eastman Chemical) include HYDRAN AP10, 20, 30, Examples of rubbers such as 40 (all manufactured by Dainippon Ink and Chemicals, Inc.) include LACSTAR 7310K, 3307B, 470
0H, 7132C (all manufactured by Dainippon Ink and Chemicals, Inc.),
Nipol Lx416, 410, 438C, 2507
(Nippon Zeon Co., Ltd.) and other poly (vinyl chloride)
Examples of poly (olefins) such as G351 and G576 (all manufactured by Nippon Zeon Co., Ltd.), and examples of poly (vinylidene chloride) s such as L502 and L513 (all manufactured by Asahi Kasei Corporation) For example, Chemipearl S
120, SA100 (all manufactured by Mitsui Petrochemical Co., Ltd.) and the like.

These polymer latexes may be used alone or as a blend of two or more if necessary.

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

Styrene which is preferably used in the present invention
As the latex of butadiene copolymer, the above-mentioned P-
3-P-8, 14, 15; LACSTAR, a commercial product
−3307B, 7132C, Nipol Lx416 and the like.

The organic silver salt-containing layer of the photothermographic material of the present invention may optionally contain a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and the like. The addition amount of these hydrophilic polymers is 30% by mass or less, more preferably 20% by mass or less of the total binder in the organic silver salt-containing layer.

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

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

The total amount of the binder in the image forming layer in the invention is preferably from 0.2 to 30 g / m ² ,
A range of 5 g / m ² is more preferred. A crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added to the image forming layer in the invention.

<Other Components> Here, other components used in the photothermographic material of the present invention will be described.

In the photothermographic material of the present invention, the solvent of the coating solution for the organic silver salt-containing layer contains 30% by mass or more of water (here, for simplicity, the solvent and the dispersion medium are collectively referred to as a solvent). Aqueous solvents are preferred. 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 in the solvent of the coating solution is 5
0 mass% or more is preferable, and 70 mass% or more is more preferable. Examples of preferable solvent compositions include water, water / methyl alcohol = 90/10, and water / methyl alcohol = 7 in addition to water.
0/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, and the like. (The numerical value is% by mass).

The antifoggants, stabilizers and stabilizer precursors which can be used in the present invention are described in JP-A-10-6.
No. 2899, paragraph 0070, European Patent Publication No. 0
No. 803764A1, page 20, line 57 to page 21, line 7
And the compounds described in JP-A-9-281637 and JP-A-9-329864. The antifoggant preferably used in the present invention is an organic halide, and for these,
Paragraph Nos. 0111 to 0 of JP-A-11-65021
No. 112 disclosed in the patent. In particular, organic halogen compounds represented by formula (P) disclosed in Japanese Patent Application No. 11-87297, JP-A-10-339934.
Preferred are organic polyhalogen compounds represented by the general formula (II) of JP-A No. 6-1980 and the organic polyhalogen compounds described in Japanese Patent Application No. 11-205330.

Hereinafter, the organic polyhalogen compound preferred in the present invention will be specifically described. The preferred polyhalogen compound of the present invention is a compound represented by the following general formula (III). General formula (III): Q- (Y) nC (Z ₁ ) (Z ₂ ) X In the general formula (III), Q represents an alkyl group, an aryl group or a heterocyclic group; Represents a valent linking group, n represents 0 or 1, Z ₁ and Z ₂ represent a halogen atom, and X represents a hydrogen atom or an electron-withdrawing group. In the general formula (III), Q preferably represents a phenyl group substituted with an electron-withdrawing group having a positive Hammett's substituent constant σp. Regarding the Hammett's substituent constant, refer to Journal of Medicinal Ch.
chemistry, 1973, Vol. 16, No. 1
1, 1207-1216 etc. can be referred to. Such preferred electron-withdrawing groups include, for example, halogen atoms (fluorine atoms (σp value: 0.06), chlorine atoms (σp value: 0.23), and bromine atoms (σp value: 0.2
3), iodine atom (σp value: 0.18)), trihalomethyl group (tribromomethyl (σp value: 0.29), trichloromethyl group (σp value: 0.33), trifluoromethyl group (σp value) : 0.54)), a cyano group (σp value:
0.66), nitro group (σp value: 0.78), aliphatic
Aryl or heterocyclic sulfonyl group (for example, methanesulfonyl group (σp value: 0.72)), aliphatic aryl or heterocyclic acyl group (for example, acetyl (σp
Value: 0.50), benzoyl group (σp value: 0.4
3)), alkynyl group (for example, C≡CH (σp value:
0.23)), an aliphatic / aryl or heterocyclic oxycarbonyl group (for example, methoxycarbonyl (σp value:
0.45), a phenoxycarbonyl group (σp value: 0.4
4)), carbamoyl group (σp value: 0.36), sulfamoyl group (σp value: 0.57), sulfoxide group, heterocyclic group, phosphoryl group and the like. The σp value is preferably in the range of 0.2 to 2.0, and 0.4 to 1.0.
Is more preferable. Among the preferred electron-withdrawing groups, particularly preferred are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group and an alkylphosphoryl group, and among them, a carbamoyl group is most preferred.

In the general formula (III), X is
Preference is given to a group capable of attracting a hydrogen atom.
Aliphatic / aryl or heterocyclic sulfonyl group, aliphatic /
Aryl or heterocyclic acyl group, aliphatic or aryl
Or a heterocyclic oxycarbonyl group, a carbamoyl group,
A rufamoyl group is more preferred, and a halogen atom is particularly preferred.
Good. Among the halogen atoms, chlorine atom, bromine atom
And iodine are preferred, and chlorine and bromine are more preferred.
Preferably, a bromine atom is particularly preferred. The general formula (III)
In the above, Y is -C (= O)-, -SO- or
SO _TwoIs preferable, and among them, -C (= O)-and -S
O_Two-Is more preferable, and -SO _Two-Is particularly preferred. n
Represents 0 or 1, and is preferably 1.

In the following, specific examples (exemplified compounds III-1 to 23) of the compound represented by formula (III) which is preferably used as an antifoggant in the present invention are shown.

[0146]

Embedded image

[0147]

Embedded image

In the photothermographic material of the present invention, the above-mentioned one
The compound represented by the general formula (III) is a non-photosensitive
10 moles per mole of silver salt^-FourUse within the range of ~ 1 mol
And preferably 10^-3Use within the range of ~ 0.8 mol
And more preferably 5 × 10 ^-3Used in the range of
It is more preferred to use In the present invention, fog
As a method of incorporating an inhibitor into the photosensitive material,
The method described in the method of containing the base agent, the organic polyhalo
Genogen compounds are also added as solid fine particle dispersion
Is preferred.

Other antifoggants include those described in
No. 1-65021, mercury (II) salt described in paragraph number 0113, benzoic acid described in paragraph number 0114 of the same publication, salicylic acid derivative described in JP-A-2000-206664, JP-A-2000-221634. In the specification, a formalin scavenger compound represented by the formula (S), a triazine compound according to claim 9 in JP-A-11-352624, and a general formula (III) described in JP-A-6-11791. And 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene.

The photothermographic material according to the invention may contain an azolium salt for the purpose of preventing fog. Examples of the azolium salt include a compound represented by the general formula (XI) described in JP-A-59-193449;
Compound described in JP-A-12581, JP-A-60-153
No. 039, the compound represented by the general formula (II). The azolium salt may be added to any part of the photothermographic material, but as an additional layer, it is preferable to add the layer to the surface having the photosensitive layer, and it is preferable to add the azolium salt to the organic silver salt-containing layer. More preferred. The azolium salt may be added at any time during the preparation of the coating solution, and when the azolium salt is added to the organic silver salt-containing layer, it may be at any time from the preparation of the organic silver salt to the preparation of the coating solution. It is preferable after salt preparation and immediately before application. The azolium salt may be added by any method such as powder, solution, and fine particle dispersion. Further, it may be added as a solution mixed with other additives such as a sensitizing dye, a reducing agent, and a color tone agent. In the present invention, the azolium salt may be added in any amount, but 1 × 10
^It is preferably from ^-6 mol to 2 mol, and more preferably from 1 × 10 ^-3 mol to 0.5 mol.

The photothermographic material of the present invention may contain a mercapto compound, such as a mercapto compound, for suppressing or accelerating the development, controlling the development, improving the spectral sensitization efficiency, and improving the storage stability before and after the development. A disulfide compound and a thione compound can be contained.
No. 99, paragraphs 0067 to 0069;
Compounds represented by the general formula (I) of JP-186572-A and paragraphs 0033 to 0052 as specific examples thereof, page 20, page 3 of EP-A-0803764A1.
Lines 6 to 56, Japanese Patent Application No. 11-273670, and the like. Among them, mercapto-substituted heteroaromatic compounds are preferred.

In the photothermographic material of the present invention, a toning agent is preferably added, and the toning agent is described in JP-A-10-628.
No. 99, paragraphs 0054-0055, EP-A-0803764A1, page 21, pages 23-48.
JP-A-2000-356317 and Japanese Patent Application No. 2000-1.
87298. 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 (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid) Phthalazines (phthalazine, phthalazine derivatives or metal salts; e.g., 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine); diammonium phthalate, sodium phthalate, potassium phthalate and tetrachlorophthalic anhydride; , 6-t-butylfuratazine, 6-
Chlorophthalazine, 5,7-dimethoxyphthalazine and 2,3-dihydrophthalazine); a combination of phthalazines and phthalic acids is preferred, and a combination of phthalazines and phthalic acids is more preferred.

The plasticizer and the lubricant which can be used in the photosensitive layer of the photothermographic material of the present invention are as follows.
JP-A No. 11-65021, paragraph No. 0117, the super-high contrast agent for forming a super-high contrast image, and the addition method and amount thereof are described in the same paragraph No. 0118, JP-A No. 11-2238.
No. 98, paragraphs 0136 to 0193, Japanese Patent Application No. 11-
Nos. 87297, Formula (H), Formulas (1) to (3), Compounds of Formulas (A) and (B), and General Formulas (III) to (V) described in Japanese Patent Application No. 11-91652. (Specific compounds: Chemical formulas 21 to 24) and the contrast enhancement accelerator are described in JP-A-11-65021, paragraph number 0102, and JP-A-11-223898, paragraph number 0194 to 0195.
It is described in.

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

When a super-high contrast agent is used in the photothermographic material of the present invention, it is preferable to use an acid formed by hydration of 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), Hexametaphosphoric acid (salt) and the like can be mentioned. Of the acids or salts thereof formed by hydration of diphosphorus pentoxide, orthophosphoric acid (salt) and hexametaphosphoric acid (salt) are particularly preferably used. Specific salts include sodium orthophosphate,
Suitable examples include sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate. Five The amount of oxidation of diphosphorus hydrating be acid or a salt thereof (coating amount per photographic material 1 m ^2), or is a desired amount depending on the performance such as sensitivity and fog,
0.1-500 mg / m ² is preferable, and 0.5-100
mg / m ² is more preferred.

<Layer Structure> The photothermographic material of the present invention may be provided with a surface protective layer for the purpose of preventing adhesion of the image forming layer. The surface protective layer may be a single layer or a plurality of layers. Regarding the surface protective layer, see JP-A-1
No. 1-65021, paragraphs 0119 to 0120, and Japanese Patent Application No. 2000-171936.

The binder for the surface protective layer of the present invention is preferably gelatin, but polyvinyl alcohol (P
It is also preferable to use VA) or to use them together. As the gelatin, inert gelatin (for example, Nitta Gelatin 750), phthalated gelatin (for example, Nitta Gelatin 801) and the like can be used. As the PVA, paragraph number 00 of JP-A-2000-171936 is used.
09-0020, including fully saponified PVA-105, partially saponified PVA-205, P
VA-335, modified polyvinyl alcohol MP-20
3 (the above are trade names manufactured by Kuraray Co., Ltd.) and the like. The amount of polyvinyl alcohol applied per surface protective layer (per layer) (per 1 m ^{2 of} support) is 0.3 to
Preferably ^{4.0g / m 2, 0.3~2.0g / m} 2 is more preferable.

In particular, when the photothermographic material of the present invention is used for printing in which dimensional change is a problem, it is preferable to use a polymer latex for the surface protective layer and the back layer. For such polymer latex, see "Synthetic Resin Emulsion (edited by Hira Okuda and Hiroshi Inagaki, published by Kobunshi Kanko (1978))" and "Application of Synthetic Latex (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, Keiji Kasahara) Molecular publishing society (1993)), "Synthesis of synthetic latex (Souichi Muroi, published by Kobunshi Kankokai (1970))" and the like, and specifically, methyl methacrylate (33.5% by mass) / Ethyl acrylate (50% by weight) / latex of methacrylic acid (16.5% by weight) copolymer, methyl methacrylate (47.5% by weight) / butadiene (4
Latex of 7.5% by mass) / itaconic acid (5% by mass) copolymer, latex of ethyl acrylate / methacrylic acid copolymer, methyl methacrylate (58.9%)
Mass%) / 2-ethylhexyl acrylate (25.4
Mass%) / styrene (8.6 mass%) / 2-hydroxyethyl methacrylate (5.1 mass%) / latex of acrylic acid (2.0 mass%) copolymer, methyl methacrylate (64.0 mass%) / styrene (9.0 mass%) / butyl acrylate (20.0 mass%) / 2-
Latex of hydroxyethyl methacrylate (5.0% by mass) / acrylic acid (2.0% by mass) copolymer; Further, as a binder for the surface protective layer, a combination of a polymer latex described in Japanese Patent Application No. 11-6872, a technique described in paragraph Nos. 0021 to 0025 in Japanese Patent Application No. 11-143058, and a technology described in Japanese Patent Application No.
The technology described in paragraph Nos. 0027 to 0028 of Japanese Patent Application No. -6872 and the technology described in paragraph Nos. 0023 to 0041 of Japanese Patent Application No. 10-199626 may be applied.
The ratio of the polymer latex in the surface protective layer is preferably from 10% by weight to 90% by weight of the whole binder, and more preferably 20% by weight or less.
It is preferably from 80% by weight to 80% by weight. Surface protective layer (1
All containing binder (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 layers per), 0.3
2.0 g / m ² is more preferred.

The preparation temperature of the image forming layer coating solution of the present invention is preferably from 30 ° C. to 65 ° C., and from 35 ° C. to 6 ° C.
Less than 0 ° C is more preferred, and more preferably 35 ° C or more and 55 ° C or less. Further, the temperature of the image forming layer coating solution immediately after the addition of the polymer latex is preferably maintained at 30 ° C. or higher and 65 ° C. or lower.

The image forming layer of the present invention comprises one or more layers on a support. When it is composed of one layer, it is composed of an organic silver salt, a photosensitive silver halide, a reducing agent and a binder, and if necessary, further contains optional materials such as a toning agent, a coating auxiliary and other auxiliary agents. When it comprises two or more layers, the first image forming layer (usually a layer adjacent to the support) contains an organic silver salt and a photosensitive silver halide,
Some other component must be included in the imaging layer or both layers. The construction of a multicolor photothermographic material may include a combination of these two layers for each color, or may include all components in a single layer as described in US Pat. No. 4,708,928. You may go out. In the case of a multi-dye, multi-color photothermographic material, each emulsion layer generally comprises a functional or non-functional barrier between the light-sensitive layers, as described in U.S. Pat. No. 4,460,681. The use of layers keeps them distinct from one another.

In the photosensitive layer of the present invention, various dyes and pigments (for example, CI Pigment) are used from the viewpoints of improving color tone, preventing interference fringes during laser exposure, and preventing irradiation.
Blue 60, C.I. I. Pigment Blue
64, C.I. I. Pigment Blue 15: 6)
Can be used. About these, WO98 / 3
6322, JP-A-10-268465, 11-3
It is described in detail in each publication of 38098.

In the photothermographic material of the present invention, an antihalation layer can be provided on the side farther from the light source than the photosensitive layer.

A photothermographic material generally has a non-photosensitive layer in addition to a photosensitive layer. The non-photosensitive layer may be arranged in such a manner that (1) a protective layer provided on the photosensitive layer (farther than the support), (2) between a plurality of photosensitive layers or between the photosensitive layer and the protective layer. , An undercoat layer provided between the photosensitive layer and the support, and a back layer provided on the opposite side of the photosensitive layer. The filter layer is
It is provided on the photosensitive material as the layer (1) or (2). The antihalation layer is provided on the photosensitive material as the layer (3) or (4).

The antihalation layer is described in paragraphs 0123 to 012 of JP-A-11-65021.
4, JP-A-11-223898, 9-230531
No., No. 10-36695, No. 10-104779,
Nos. 11-231457, 11-352625, and 11-352626. 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 using a dye having absorption in the visible region to prevent halation, it is preferable that substantially no color of the dye remains after image formation, and a means for decoloring by the heat of heat development is used. It is particularly preferable to add a thermal decoloring dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These techniques are described in, for example, JP-A-11-231457.

The amount of the decolorizable dye is determined depending on the use of the dye. Generally, the optical density (absorbance) measured at the target wavelength is used in an amount exceeding 0.1.
The optical density is preferably from 0.2 to 2. The amount of the dye used to obtain such an optical density is generally 0.1.
It is about 001 to 1 g / m ² .

When the dye is decolored in this manner, the optical density after thermal development can be reduced to 0.1 or less. Two or more decolorizable dyes may be used in combination in a heat-decolorable recording material or a photothermographic material. Similarly, two or more base precursors may be used in combination. In thermal decoloring using such a decoloring dye and a base precursor,
When combined with a base precursor as described in JP-A-11-352626, a substance (for example, diphenylsulfone, 4-chlorophenyl (phenyl) sulfone) that lowers the melting point by 3 ° C. (deg) or more can be used in combination with thermal decolorization. It is preferable in terms of properties and the like.

In the present invention, a colorant having an absorption maximum at 300 to 450 nm can be added for the purpose of improving the silver tone and the temporal change of the image. Such coloring agents are described in JP-A-62-210458 and 63-1040.
No. 46, No. 63-103235, No. 63-20884
No. 6, No. 63-306436, No. 63-314535
, Japanese Patent Application Laid-Open No. 01-61745, and Japanese Patent Application No. Hei.
1-276751. Such a coloring agent is usually added in the range of 0.1 mg / m ^{2 to 1} g / m ² , and the layer to be added is preferably a back layer provided on the side opposite to the photosensitive layer.

The photothermographic material of the present invention has at least one light-sensitive layer containing a light-sensitive silver halide emulsion on one side of a support, and has a back layer on the other side.
It is preferably a so-called one-sided photosensitive material.

In the present invention, it is preferable to add a matting agent for improving transportability.
JP-A-11-65021, paragraph numbers 0126 to 01
27. The matting agent is preferably 1 to 400 mg / m ² when expressed in the amount of coating per m ² of the photosensitive material.
m ² , more preferably 5 to 300 mg / m ² . The matting degree of the emulsion surface may be any value as long as stardust failure does not occur, but the Beck smoothness is preferably 30 seconds or more and 2000 seconds or less, and particularly preferably 40 seconds or more and 1500 seconds or less. The Beck smoothness is based on Japanese Industrial Standard (JIS) P811.
9 "Smoothness test method of paper and paperboard with Beck tester"
And TAPPI standard method T479.

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

In the present invention, the matting agent is preferably contained in the outermost surface layer of the light-sensitive material, a layer functioning as the outermost surface layer, or a layer near the outer surface, and also acts as a so-called protective layer. Preferably it is contained in a layer.

The back layer applicable to the present invention is described in paragraph No. 01 of JP-A-11-65021.
28-0130.

The photothermographic material of the present invention preferably has a film surface pH of 7.0 or less before heat development, and 6.6.
It is more preferred that: The lower limit is
Although there is no particular limitation, it is about 3. The most preferred pH range is between 4 and 6.2. To adjust the film surface pH, an organic acid such as a phthalic acid derivative, a non-volatile acid such as sulfuric acid, or a volatile base such as ammonia is used.
Is preferable from the viewpoint of reducing In particular, ammonia is preferable in achieving a low film surface pH since ammonia is easily volatilized and can be removed before the application step and the heat development. It is also preferable to use ammonia in combination with a non-volatile base such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. The method of measuring the film surface pH is described in paragraph No. 0123 of Japanese Patent Application No. 11-87297.

A hardening agent may be used for each layer such as the photosensitive layer, the surface protective layer and the back layer of the present invention. Examples of hardeners include T.I. H. James "THE THEORY"
OFTHE PHOTOGRAPHIC PROCES
S FOURTH EDITION "(Macmill
an Publishing Co. , Inc. Published,
There are various methods described on pages 77 to 87 (1977), chromium alum, 2,4-dichloro-6-hydroxy-s-triazine sodium salt, N, N-ethylenebis (vinylsulfoneacetamide), N, N Propylene bis (vinylsulfone acetamide), polyvalent metal ions described on page 78 of the same book, U.S. Pat.
Preferred are polyisocyanates such as 1,060 and JP-A-6-208193, epoxy compounds such as U.S. Pat. No. 4,791,042, and vinylsulfone compounds such as JP-A-62-89048. Can be

The hardener is added as a solution, and the time of adding this solution to the coating solution for the protective layer is determined by the 180
The time is from minutes to immediately before, preferably from 60 minutes to 10 seconds, but the mixing method and mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, there is a method of mixing in a tank in which the average residence time calculated from the addition flow rate and the amount of liquid sent to the coater is set to a desired time, Harnby, M .; F. Edw
ards, A .; W. There is a method using a static mixer or the like described in Chapter 8 of Nienow, "Liquid Mixing Technology" translated by Koji Takahashi (Nikkan Kogyo Shimbun, 1989).

The surfactant applicable to the photothermographic material of the present invention is described in paragraph No. 0132 of JP-A-11-65021, and the solvent is described in paragraph No. 013 of the same publication.
3. Paragraph No. 0134 of the same publication for the support, paragraph No. 0135 of the same publication for the antistatic or conductive layer, and paragraph No. 0136 of the same publication for the method of obtaining a color image
As for the slipping agent, JP-A-11-84573, paragraph numbers 0061 to 0064 and Japanese Patent Application No. 11-106881.
Paragraph Nos. 0049 to 0062 are described.

The photothermographic material of the present invention may further contain an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid. Various additives are added to either the photosensitive layer or the non-photosensitive layer. About them, WO98 / 36322, EP803376A1,
JP-A Nos. 10-186567 and 10-18568 can be referred to.

<Support> The support used in the photothermographic material of the present invention will be described below. The transparent support used in the present invention is heat-treated at a temperature in the range of 130 to 185 ° C. in order to reduce internal strain remaining in the film at the time of biaxial stretching and to eliminate heat shrinkage strain generated during thermal development processing. Polyester, particularly polyethylene terephthalate, is preferably used. In the case of a photothermographic material for medical use, the transparent support is made of a blue dye (for example,
The dye may be colored with the dye-1) described in Examples of -240877, or may be uncolored. As the support, JP-A-1
JP-A-1-84574, water-soluble polyester;
Styrene-butadiene copolymer disclosed in JP-A-186565, JP-A-2000-39684 and Japanese Patent Application No. 11-1068.
It is preferable to apply an undercoating technique such as a vinylidene chloride copolymer described in paragraph No. 0063 to 0080 of the specification No. 81. Further, the antistatic layer or the undercoat is described in JP-A-56-143430, JP-A-56-143431, JP-A-58-62646, JP-A-56-120519, and JP-A-11-84573, paragraphs 0040 to 00
51, US Patent No. 5,575,957, JP-A-11-
The technology described in paragraph Nos. 0078 to 0084 of Japanese Patent No. 223898 can be applied.

The photothermographic material of the present invention is preferably of a monosheet type (a type capable of forming an image on the photothermographic material without using another sheet such as an image receiving material).

(Preparation of Photothermographic Material) The photothermographic material of the present invention may be applied by any method. Specifically, various coating operations including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in US Pat. No. 2,681,294. Is used, and Stephen F. is used. Kistle
r, Peter M.R. "LI by Schweizer
QUID FILM COATING "(CHAPMA
N & HALL, 1997) p. 399-53
Extrusion coating or slide coating described on page 6 is preferably used, and particularly preferably slide coating is used. For examples of slide coater shapes used for slide coating, see Ibid.
Figure 11b. In one. Also, if desired, the method described in the same book, pages 399 to 536, U.S. Pat. No. 2,761,791 and British Patent 837,095.
According to the method described in (1), two or more layers can be simultaneously coated.

The coating solution for the organic silver salt-containing layer in the present invention comprises:
It is preferably a so-called thixotropic fluid. For this technique, reference can be made to JP-A-11-52509. The coating solution of the organic silver salt-containing layer according to the invention has a viscosity of 4 at a shear rate of 0.1 S ^-1 .
It is preferably from 100 mPa · s to 100,000 mPa · s, and more preferably from 500 mPa · s to 20,000 mPa · s.
The following is more preferred. Further, at a shear rate of 1000 S ^−1, it is preferably from 1 mPa · s to 200 mPa · s, and more preferably from 5 mPa · s to 80 mPa · s.

Techniques which can be used for the photothermographic material of the present invention include EP803376A1 and EP88.
No. 3022A1, WO98 / 36322, JP-A-56
-62648, 58-62644, JP-A-9-4
No. 3766, 9-281637, 9-297367
No. 9-304869, No. 9-31405, No. 9-329865, No. 10-10669, No. 10-
No. 62899, No. 10-69023, No. 10-186
No. 568, No. 10-90823, No. 10-17106
No. 3, No. 10-186565, No. 10-186567
Nos. 10-186569 to 10-186572
No. 10-197974, No. 10-197982
No. 10-197983, No. 10-197985 to No. 10-197987, No. 10-207001,
Nos. 10-207004, 10-221807, 10-282601, 10-288823, 1
Nos. 0-288824, 10-307365, and 10
No.-312038, No.10-339934, No.11-
No. 7100, No. 11-15105, No. 11-2420
No. 0, No. 11-24201, No. 11-30832,
11-84574, 11-65021, 11
Nos. 109547, 11-125880, 11-
Nos. 129629 and 11-133536 to 11-1
No. 33538, No. 11-133542, No. 11-13
No. 3543, No. 11-223898, No. 11-352
No. 627, No. 11-305377, No. 11-3053
No. 78, No. 11-305384, No. 11-30538
No. 0, No. 11-316435, No. 11-327076
No. 11-338096 and No. 11-338098
Nos. 11-338099 and 11-343420, Japanese Patent Application Nos. 2000-187298 and 2000
No.-10229, No.2000-47345, No.200
Nos. 0-206642, 2000-98530, 2
000-98531, 2000-112059,
No. 2000-112060, No. 2000-11210
No. 4, No. 2000-112064, No. 2000-17
Each specification of 1936 is also mentioned.

(Image formation using photothermographic material) The photothermographic material of the present invention may be developed by any method, but is usually developed by elevating the temperature of the photothermographic material exposed imagewise. . The development temperature is 80 to 250 ° C.
Is preferable, and 100 to 140 ° C. is more preferable. The development time is preferably 1 to 60 seconds, more preferably 5 to 30 seconds, and particularly preferably 10 to 20 seconds.

As a method of heat development, a plate heater method is preferable. The heat development method using a plate heater method is preferably a method described in JP-A-11-133572, and a visible image is obtained by bringing the heat-developable photosensitive material having a latent image formed thereon into contact with a heating means in a heat development section. A heat developing device, wherein the heating means comprises a plate heater, and a plurality of pressing rollers are disposed to face each other along one surface of the plate heater, and the pressing roller is disposed between the pressing roller and the plate heater. A heat developing apparatus for performing heat development by passing a heat-developable photosensitive material. The plate heater is divided into 2 to 6 stages, and the tip is 1 to 1
It is preferable to lower the temperature by about 0 ° C. Such a method is also described in JP-A-54-30032, in which water and organic solvents contained in the photothermographic material can be excluded from the system. The change in the shape of the support of the photothermographic material due to the heating of the photothermographic material can also be suppressed.

The light-sensitive material of the present invention may be exposed by any method, but a laser beam is preferred as an exposure light source.
As the laser beam according to the present invention, a gas laser (Ar
⁺ , He-Ne), a YAG laser, a dye laser, a semiconductor laser and the like. Further, a semiconductor laser and a second harmonic generation element can be used. Preferably, it is a gas or semiconductor laser emitting red to infrared light.

As a medical laser imager having an exposure section and a heat development section, Fuji Medical Dry Laser Imager FM-DPL can be mentioned. Regarding FM-DPL, Fuji Medic
al Review No. 8, page 39-55
It goes without saying that those techniques are applied as a laser imager for the photothermographic material of the present invention. It can also be applied as a photothermographic material for laser imagers in "AD network" proposed by Fuji Medical System as a network system conforming to the DICOM standard.

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

[0188]

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

[Preparation of PET support] Using terephthalic acid and ethylene glycol, an intrinsic viscosity IV =
0.66 (phenol / tetrachloroethane = 6/4
(Measured at 25 ° C. in the mass ratio). This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and quenched to prepare an unstretched film having a thickness of 175 μm after heat setting.

This was performed by using rolls having different peripheral speeds by 3.3.
The film was longitudinally stretched by a factor of 2, and then transversely stretched by a factor of 4.5. The temperatures at this time were 110 ° C. and 130 ° C., respectively. After that, it was heat-set at 240 ° C. for 20 seconds, and relaxed 4% in the horizontal direction at the same temperature. Then, after slitting the chuck portion of the tenter, knurling was performed on both ends, and it was wound up at 4 kg / cm ² (4 × 10 ⁴ Pa) to obtain a roll having a thickness of 175 μm.

[Surface Corona Treatment] Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, 0.375 kV was applied to the support.
-It turned out that the processing of A * minute / m < ² > was performed.
The processing frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

[Preparation of Undercoating Support] <Preparation of Undercoating Layer Coating Solution> -Prescription (for undercoating layer on the photosensitive layer side) -Pesthresin A-515GB manufactured by Takamatsu Yushi Co., Ltd. (30% by mass solution) 234 g -Polyethylene Glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 10 mass% solution 21.5 g ・ Soken Chemical Co., Ltd. MP-1000 (polymer fine particles, average particle diameter 0.4 μm) 0.91 g ・ Distilled water 744 ml

-Prescription (for the first layer on the back surface)--Styrene-butadiene copolymer latex 158 g (solid content 40% by mass, styrene / butadiene mass ratio = 68/32) -2,4-dichloro-6-hydroxy -S- Triazine sodium salt 8% by mass aqueous solution 20g ・ 1% by mass aqueous solution of sodium laurylbenzenesulfonate 10ml ・ Distilled water 854ml

-Prescription (for back surface side second layer)-SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion) 84 g Gelatin (10 mass% aqueous solution) 89 .2g ・ Shin-Etsu Chemical Co., Ltd. Metroose TC-5 (2% by mass aqueous solution) 8.6g ・ Soken Chemical Co., Ltd. MP-1000 0.01g ・ 1% by mass aqueous solution of sodium dodecylbenzenesulfonate 10ml ・ NaOH ( 6% ・ Proxel (manufactured by ICI) 1ml ・ Distilled water 805ml

<Preparation of Undercoated Support> The above thickness of 175 μm
m, the corona discharge treatment was applied to both sides of the biaxially stretched polyethylene terephthalate support, and the undercoating solution formulation was wet-coated on one surface (photosensitive layer surface) with a wire bar at a wet application amount of 6.6 ml / m ² ( (Per side) and dried at 180 ° C for 5 minutes. Then, the undercoating liquid formulation was applied to the back surface (back surface) with a wire bar so that the wet application amount was 5.7 ml / m ^2. After drying at 180 ° C. for 5 minutes, the undercoating composition was further applied to the back surface (back surface) with a wire bar so that the wet application amount was 7.7 ml / m ^2.
After drying at 0 ° C. for 6 minutes, an undercoat support was prepared.

[Preparation of back surface coating solution] <Preparation of solid fine particle dispersion (a) of base precursor>
64 g of the base precursor compound 11, 28 g of diphenylsulfone, and 10 g of Demol N, a surfactant manufactured by Kao Corporation, were mixed with 220 ml of distilled water, and the mixture was subjected to a sand mill (1/4 Gallon sand grinder mill,
The beads were dispersed using IMEX Co., Ltd.) to obtain a solid fine particle dispersion (a) of a base precursor compound having an average particle diameter of 0.2 μm.

<Preparation of Dye Solid Fine Particle Dispersion> 9.6 g of cyanine dye compound 13 and 5.8 g of sodium p-dodecylbenzenesulfonate were added to 305 ml of distilled water.
The mixture was mixed using a sand mill (1/4 Gallon Sand Grinder Mill, manufactured by IMEX Co., Ltd.) to obtain a dispersion of fine solid dye particles having an average particle diameter of 0.2 μm.

<Preparation of coating solution for antihalation layer> 17 g of gelatin, 9.6 g of polyacrylamide, 70 g of solid fine particle dispersion (a) of the above base precursor, 56 g of solid fine particle dispersion of dye, and monodispersed polymethyl methacrylate fine particles (average) Particle size 8 μm, particle size standard deviation 0.
4) 1.5 g, benzoisothiazolinone 0.03 g, sodium polyethylene sulfonate 2.2 g, blue dye compound 14 0.2 g, yellow dye compound 15 3.9.
g and water (844 ml) were mixed to prepare an antihalation layer coating solution.

<Preparation of Back Surface Protective Layer Coating Solution>
The mixture was kept at 0 ° C., and gelatin 50 g, polystyrene sodium sulfonate 0.2 g, N, N-ethylenebis (vinylsulfoneacetamide) 2.4 g, sodium t-octylphenoxyethoxyethaneethanesulfonate 1 g,
Benzoisothiazolinone 30 mg, fluorinated surfactant (F-1: N-perfluorooctylsulfonyl-N
37 mg of a fluorinated surfactant (F-2: polyethylene glycol mono (N-
Perfluorooctylsulfonyl-N-propyl-2-
Aminoethyl) ether [average degree of polymerization of ethylene oxide 15]) 0.15 g, fluorinated surfactant (F-3)
64 mg, fluorine-based surfactant (F-4) 32 mg, acrylic acid / ethyl acrylate copolymer (copolymerization mass ratio 5/95) 8.8 g, Aerosol OT (manufactured by American Cyanamid Co.) 0.6 g, The liquid paraffin emulsion was mixed with 1.8 g of liquid paraffin and 950 ml of water to prepare a coating liquid for the back surface protective layer.

[Preparation of each component contained in emulsion layer coating solution] <Silver halide emulsion><< Preparation of silver halide emulsion 1 >> 1 in 1421 ml of distilled water
3.1 ml of a 0.1% by weight potassium bromide solution was added,
While stirring a liquid containing 3.5 ml of sulfuric acid having a mol / L concentration and 31.7 g of phthalated gelatin in a stainless steel reaction bottle, the liquid temperature was maintained at 30 ° C., and distilled water was added to 22.22 g of silver nitrate. A solution A diluted to 0.4 ml and a solution B obtained by diluting 15.3 g of potassium bromide and 0.8 g of potassium iodide to a volume of 97.4 ml with distilled water at a constant flow rate.
The whole amount was added over 5 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and further 10.8 ml of a 10% by mass aqueous solution of benzimidazole was added. Further, distilled water was added to 51.86 g of silver nitrate to make 317.5 m
Solution C diluted to 1 l and solution D prepared by diluting 44.2 g of potassium bromide and 2.2 g of potassium iodide to a volume of 400 ml with distilled water were all added at a constant flow rate over 20 minutes. Solution D was added by the controlled double jet method while maintaining the pAg at 8.1. Iridium (III) hexachloride so as to be 1 × 10 ^-4 mol per mol of silver
The acid potassium salt was added in its entirety 10 minutes after the start of adding the solution C and the solution D. Five seconds after the completion of the addition of the solution C, an aqueous solution of potassium hexairon cyanide (II) was added in a total amount of 3 × 10 ^-4 mol per mol of silver. 0.5mol /
The pH was adjusted to 3.8 using sulfuric acid having an L concentration, stirring was stopped, and a precipitation / desalting / washing process was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide, and pA
A silver halide dispersion of g 8.0 was prepared.

While stirring the above silver halide dispersion, 3
While maintaining the temperature at 8 ° C., 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added,
After 40 minutes, a methanol solution having a molar ratio of spectral sensitizing dye A to spectral sensitizing dye B of 1: 1 was added at 1.2 × 10 ⁻³ mol per mol of silver as a total of spectral sensitizing dyes A and B. After a minute, the temperature was raised to 47 ° C. Twenty minutes after the temperature was raised, 7.6 × 10 ⁻⁵ mol of sodium benzenethiosulfonate was added to 1 mol of silver with a methanol solution, and further 5 minutes later, tellurium sensitizer C was added with 2 mol / mol of silver with a methanol solution. .9 × 10 ^-4
Mol was added and the mixture was aged for 91 minutes. 1.3 ml of a 0.8% by weight methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added, and after another 4 minutes, 5-methyl-2-methyl-2-methyl-2-methyl-N-diethyl-melamine was added.
Mercaptobenzimidazole in methanol with silver 1
4.8 × 10 ^-3 mole per mole and 1-phenyl-2-
Heptyl-5-mercapto-1,3,4-triazole was added in a methanol solution at 5.4 × 10 ⁻³ mol per mol of silver to prepare a silver halide emulsion 1.

The grains in the prepared silver halide emulsion are as follows:
The silver iodobromide particles contained 3.5 mol% of iodine having an average equivalent sphere diameter of 0.042 μm and a coefficient of variation of equivalent sphere diameter of 20% uniformly. The particle size and the like were measured using an electron microscope.
It was determined from the average of 0 particles. The {100} plane ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of Silver Halide Emulsion 2 >> In the preparation of silver halide emulsion 1, a liquid temperature of 30 ° C. during grain formation was adjusted to 4 ° C.
The temperature was changed to 7 ° C., the solution B was changed to dilute 15.9 g of potassium bromide to a volume of 97.4 ml with distilled water, and the solution D was prepared by diluting 45.8 g of potassium bromide with a volume of 400 m in distilled water.
The silver halide emulsion 2 was prepared in the same manner except that the dilution was changed to 1 and the addition time of the solution C was changed to 30 minutes to remove potassium hexacyanoferrate (II). Precipitation / desalting / washing / dispersion was carried out in the same manner as in silver halide emulsion 1. Further, the addition amount of a methanol solution having a molar ratio of 1: 1 between the spectral sensitizing dye A and the spectral sensitizing dye B is 7.5 × 10 5 as the total amount of the spectral sensitizing dye A and the spectral sensitizing dye B per mole of silver.
^-4 mol, the tellurium sensitizer C was added in an amount of 1.
Silver halide except that 1 × 10 ^-4 mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole was changed to 3.3 × 10 ^-3 mol per mol of silver. Emulsion 1, chemical sensitization and 5-methyl-
2-mercaptobenzimidazole, 1-phenyl-2
-Heptyl-5-mercapto-1,3,4-triazole was added to obtain a silver halide emulsion 2. The emulsion grains of the silver halide emulsion 2 had an average sphere equivalent diameter of 0.080 μm.
m, pure silver bromide cubic grains having a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of Silver Halide Emulsion 3 >> In the preparation of silver halide emulsion 1, a liquid temperature of 30 ° C. during grain formation was adjusted to 2 ° C.
Except that the temperature was changed to 7.degree.
Was prepared. Further, precipitation / desalting / washing / dispersion / dispersion was performed in the same manner as in silver halide emulsion 1. The addition amount of the solid dispersion (aqueous gelatin solution) having a molar ratio of 1: 1 between the spectral sensitizing dye A and the spectral sensitizing dye B is 6 × as the total amount of the spectral sensitizing dye A and the spectral sensitizing dye B per mole of silver. 10 ^-3 moles, except that the amount of tellurium sensitizer C was changed to 5.2 × 10 ^-4 mol per 1 mol of silver, in the same manner as the silver halide emulsion 1, to obtain a silver halide emulsion 3 . The emulsion grains of the silver halide emulsion 3 were:
The silver iodobromide particles contained 3.5 mol% of iodine having an average equivalent sphere diameter of 0.034 μm and a coefficient of variation of equivalent sphere diameter of 20%.

<< Preparation of Silver Halide Mixed Emulsion A for Coating Solution >> 70% by mass of silver halide emulsion 1, 15% by mass of silver halide emulsion 2 and 15% by mass of silver halide emulsion 3 were dissolved. Zolium iodide was added as a 1% by mass aqueous solution in an amount of 7 × 10 ⁻³ mol per mol of silver. Further, water was added so that the silver halide content per 1 kg of the silver halide mixed emulsion for the coating solution was 38.2 g as silver.

<Preparation of Organic Silver Salt Dispersions A to G> 258.5 mol of an organic acid and 423 of distilled water were prepared so as to obtain the composition shown in Table 1.
L, 49.2 L of 5 mol / L NaOH aqueous solution, t
120 L of ert-butanol was mixed, and the mixture was stirred and reacted at 75 ° C. for 1 hour to obtain a sodium organic acid solution. Separately, 206.2 L of an aqueous solution of 40.4 kg of silver nitrate (pH
4.0) was prepared and kept warm at 10 ° C. The reaction vessel containing 635 L of distilled water and 30 L of tert-butanol was kept at 30 ° C., and with sufficient stirring, the total amount of the organic acid sodium salt solution and the total amount of the silver nitrate aqueous solution were kept at a constant flow rate of 93 minutes and 15 seconds, respectively. Added over 90 minutes. At this time, only the aqueous solution of silver nitrate was added for 11 minutes after the start of the aqueous solution of silver nitrate, and then the addition of the organic acid sodium solution was started.
During the second, only the organic acid sodium solution was added. At this time, the reaction temperature in the reaction vessel was set to the temperature shown in Table 1, and the external temperature was controlled so that the liquid temperature became constant.
Further, the piping of the addition system of the organic acid sodium solution was kept warm by circulating warm water outside the double tube, and the liquid temperature at the outlet of the tip of the addition nozzle was adjusted to 75 ° C. The piping of the silver nitrate aqueous solution addition system was kept warm by circulating cold water outside the double pipe. The addition position of the organic acid sodium solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically with respect to the stirring axis, and were adjusted to a height such that they did not come into contact with the reaction solution.

<< Aging / Centrifugal Filtration >> After the addition of the sodium organic acid solution, the mixture was left to stir at the same temperature for 20 minutes.
The temperature was raised to 35 ° C. over 30 minutes, and then aging was performed for 210 minutes. Immediately after ripening, the solid content was separated by centrifugal filtration.
The solid was washed with water until the conductivity of the filtered water became 30 μS / cm. At that time, in order to promote the decrease in conductivity, an operation of adding pure water to the wet cake to form a slurry was performed three times. The obtained organic silver wet cake is centrifuged with a centrifugal force G of 70.
It was shaken for 1 hour at 0. G is 1.119 × 1
0 ^-5 × vessel radius (cm) × rotational speed (rpm) is represented by ^2. The solid content of the organic silver wet cake thus obtained (measured by drying 1 g of the wet cake at 110 ° C. for 2 hours) was 44%.

<< Preliminary Dispersion >> 19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water were added to a wet cake having a dry solid content of 260 kg,
After the total amount was adjusted to 1000 kg, the mixture was slurried with a dissolver blade and further preliminarily dispersed with a pipeline mixer (made by Mizuho Kogyo: PM-10).

<< Final Dispersion >> Next, the pre-dispersed undiluted solution was subjected to a dispersing machine (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) at a pressure of 1260 kg / cm ^2. (12.6 MPa), and treated three times to obtain an organic silver salt dispersion (silver behenate dispersion). The shape characteristic values of the dispersion were the same as those after washing. In the cooling operation, a coiled heat exchanger was mounted before and after the interaction chamber, and the dispersion temperature was set at 18 ° C. by adjusting the temperature of the refrigerant. The organic silver salt particles contained in the organic silver salt dispersions A to G thus obtained have a volume-weighted average diameter (equivalent sphere diameter) and a coefficient of variation of the volume-weighted average diameter (equivalent sphere diameter) as shown in Table 1. there were. The particle size is measured using MasterSize from Malvern Instruments Ltd.
Performed at rX.

[0210]

[Table 1]

<Preparation of Reducing Agent Dispersion or Reducing Agent Complex Dispersion><< Preparation of Reducing Agent Dispersion >> 10 kg of a reducing agent (described separately) and 20% by mass of modified polyvinyl alcohol (Poval MP203, manufactured by Kuraray Co., Ltd.) 16 kg of water was added to 10 kg of the aqueous solution and mixed well to form a slurry. The slurry was sent by 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 30 minutes, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the reducing agent to 25% by mass to obtain a reducing agent dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.42 μm and a maximum particle diameter of 2.0 μm or less. The resulting reducing agent dispersion had a pore size of 10.0 μm.
And filtered to remove foreign matter such as dust, and stored.

<< Preparation of Dispersion of Reducing Agent Complex >> To 10 kg of a 10 mass% aqueous solution of a reducing agent complex (described separately), 0.12 kg of triphenylphosphine oxide and modified polyvinyl alcohol (Poval MP203, manufactured by Kuraray Co., Ltd.) 7.2 kg of water was added and mixed well to form a slurry. The slurry was sent by 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 30 minutes, and then benzoisothiazolinone sodium salt was added. 0.2 g and water were added to adjust the concentration of the reducing agent to 25% by mass to obtain a reducing agent complex dispersion. The reducing agent complex particles contained in the thus obtained reducing agent complex dispersion had a median diameter of 0.46 μm and a maximum particle diameter of 1.6 μm or less. The resulting reducing agent complex 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 Dispersion of Hydrogen Bonding Compound> 10 kg of a hydrogen bonding compound (described separately) and modified polyvinyl alcohol (Poval MP203, manufactured by Kuraray Co., Ltd.)
10 kg of water was added to 20 kg of a 10% by mass aqueous solution of the above, and mixed well to form a slurry. The slurry was sent by 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 30 minutes.
0.2 g of benzoisothiazolinone sodium salt and water were added to adjust the concentration of the hydrogen bonding compound to 22% by mass to obtain a hydrogen bonding compound dispersion. The compound particles contained in the dispersion thus obtained have a median diameter of 0.35 μm.
m, the maximum particle size was 1.5 μm or less. The resulting 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.

<Preparation of Organic Polyhalogen Compound Dispersion><< Preparation of Organic Polyhalogen Compound-1 Dispersion >> 10 kg of organic polyhalogen compound-1 (2-tribromomethanesulfonylnaphthalene) and modified polyvinyl alcohol (Kuraray Co., Ltd.) 10% of a 20% by weight aqueous solution of Poval MP203), 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate,
16 kg of water was added and mixed well to form a slurry. This slurry was sent by 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 5 hours, and then sodium benzoisothiazolinone sodium salt was added. 2 g and water were added to adjust the concentration of the organic polyhalogen compound to 23.5% 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 0.36 μm and a maximum particle diameter of 2.0 μm or less. The resulting organic polyhalogen compound dispersion has a pore size of 1
Filtration was performed with a 0.0 μm polypropylene filter to remove foreign substances such as dust, and stored.

<< Preparation of Dispersion of Organic Polyhalogen Compound-2 >> 10 kg of organic polyhalogen compound-2 (tribromomethanesulfonylbenzene) and 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 and 14
kg, and mixed well to form a slurry. The slurry was sent by a diaphragm pump and had an average diameter of 0.1 mm.
After dispersing for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with 5 mm zirconia beads, benzoisothiazolinone sodium salt 0.2
g and water were added to adjust the concentration of the organic polyhalogen compound to 26% by mass.
A dispersion was obtained. 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 resulting organic polyhalogen compound dispersion has a pore size of 10.0 μm.
Then, the mixture was filtered with a polypropylene filter of m to remove foreign substances such as dust, and stored.

<< Preparation of Dispersion of Organic Polyhalogen Compound-3 >> 10 kg of organic polyhalogen compound-3 (N-butyl-3-tribromomethanesulfonylbenzamide) and modified polyvinyl alcohol (Poval MP20 manufactured by Kuraray Co., Ltd.)
20 kg of a 10% by mass aqueous solution of 3), 0.4 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate, and 8 kg of water were added and mixed well to form a slurry. This slurry is fed by a diaphragm pump, and a horizontal sand mill (UVM-2: IMEX Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm.
After dispersing for 5 hours, 0.2 g of benzoisothiazolinone sodium salt and water were added to adjust the concentration of the organic polyhalogen compound to 25% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-3 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.36 μm and a maximum particle diameter of 1.5 μm or less.
The resulting organic polyhalogen compound dispersion had a pore size of 3.0 μm.
Then, the mixture was filtered with a polypropylene filter of m to remove foreign substances such as dust, and stored.

<Preparation of Phthalazine Compound-1 Solution> 8k
g modified Kuraray Co., Ltd. modified polyvinyl alcohol MP20
Was dissolved in 174.57 kg of water, and then 3.15 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate and 14.28 kg of a 70% by mass aqueous solution of a phthalazine compound (6-isopropylphthalazine) were added. To prepare a 5% by weight solution.

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

<Preparation of Pigment Dispersion> I. Pigme
To 64 g of nt Blue 60 and 6.4 g of Demol N manufactured by Kao Corporation, 250 g of water was added and mixed well to form a slurry. Zirconia beads 80 having an average diameter of 0.5 mm
0 g was prepared, put into a vessel together with the slurry, and dispersed for 25 hours with a dispersing machine (1 / 4G sand grinder mill: manufactured by Imex Co., Ltd.) to obtain a pigment-1 dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<Preparation of SBR latex liquid> Tg = 23
C. SBR latex was prepared as follows. Using ammonium persulfate as a polymerization initiator and an anionic surfactant as an emulsifier, 70.5 parts by mass of styrene, 26.5 parts by mass of butadiene and 3 parts by mass of acrylic acid were emulsion-polymerized, and then aged at 80 ° C. for 8 hours. went. Then 4
Cooled to 0 ° C, adjusted to pH 7.0 with aqueous ammonia,
Further, Sandet BL manufactured by Sanyo Chemical Industries, Ltd. was added so as to be 0.22%. Next, a 5% aqueous sodium hydroxide solution was added to adjust the pH to 8.3, and the pH was further adjusted with aqueous ammonia.
Adjusted to H8.4. Na used at this time
The molar ratio of ⁺ ions to NH ₄ ⁺ ions was 1: 2.3. Further, 0.15 ml of a 7% aqueous solution of sodium salt of benzoisothiazolinone was added to 1 kg of this solution, and S
A BR latex solution was prepared.

(SBR latex: -St (70.5)
-Bu (26.5) -AA (3)-latex) T
g 23 ° C, average particle size 0.1 μm, concentration 43% by mass, 25 ° C 60% R
Equilibrium water content in H: 0.6% by mass, ionic conductivity: 4.
2 mS / cm (Ion conductivity was measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo KK, and a latex stock solution (43% by mass) was measured at 25 ° C), pH 8.4. Tg
SBR latexes having different styrene and butadiene ratios were appropriately changed, and prepared by the same method.

[Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution] <Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution-1 (1A to 1G)> Each of the organic silver salt dispersions A to G obtained above was prepared in 1000 parts.
g, water 125 ml, reducing agent dispersion (amount to be applied in Table 2), pigment dispersion 27 g, organic polyhalogen compound-1 dispersion 82 g, organic polyhalogen compound-2 dispersion 40 g, phthalazine compound 173 g of the solution, 1082 g of an SBR latex (Tg: 20.5 ° C.) solution, and 9 g of an aqueous solution of a mercapto compound are sequentially added. And applied.

The viscosity of the emulsion layer coating solution was measured at 40 ° C. (No. 1 rotor, 60 rpm
pm) was 85 [mPa · s].

25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd.
The viscosity of the coating solution at the shear rate is 0.1, 1, 10, 1
For 00 and 1000 [1 / sec], 150
0, 220, 70, 40, and 20 [mPa · s].

<Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution-2>
1000 g of the organic silver salt dispersion D obtained above, 104 m of water
1, 30 g of pigment dispersion, 21 g of organic polyhalogen compound-2 dispersion, and 69 g of organic polyhalogen compound-3 dispersion
g, phthalazine compound-1 solution 173 g, SBR latex (Tg: 23 ° C.) solution 1082 g, a reducing agent or a reducing agent complex (described in Table 2) 258 g, mercapto compound-1
9 g of an aqueous solution was sequentially added, and 110 g of a silver halide mixed emulsion A for a coating solution was added immediately before coating, and the well-mixed emulsion layer coating solution was directly sent to a coating die and coated.

[Preparation of Emulsion Surface Intermediate Layer Coating Solution] 772 g of a 10% by mass aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), and a 20% by mass dispersion of a pigment 5.3.
g, 27.5% by mass of a latex of methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization ratio 64/9/20/5/2) and aerosol OT (American Siana) 5% aqueous solution of
1, 20 mass% aqueous solution of diammonium phthalate
0.5 ml, water was added to make the total amount 880 g, pH
Was adjusted to 7.5 with NaOH to prepare a coating solution for the intermediate layer, and the solution was fed to a coating die at 10 ml / m ² . The viscosity of the coating solution was 40 ° C. using a B-type viscometer (No. 1).
Rotor, 60 rpm) was 21 [mPa · s].

[Preparation of Coating Solution for Emulsion Surface Protective Layer First Layer] Inert gelatin (64 g) was dissolved in water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio: 6)
4/9/20/5/2) 27.5% by mass latex liquid 8
0 g, 10% methanol solution of phthalic acid in 23m
1, 23 ml of a 10% by mass aqueous solution of 4-methylphthalic acid,
28 ml of 0.5 mol / L sulfuric acid, 5 ml of a 5% by mass aqueous solution of aerosol OT (manufactured by American Cyanamid), 0.5 g of phenoxyethanol and 0.1 g of benzoisothiazolinone are added to make a total amount of 750 g. Was added to water to form a coating solution, and a mixture prepared by mixing 26 ml of 4% by mass chrome alum with a static mixer immediately before coating was sent to a coating die at 18.6 ml / m ² . The viscosity of the coating solution was measured at 40 ° C. using a B-type viscometer (No.
It was 17 [mPa · s] with one rotor at 60 rpm.

[Preparation of Coating Solution for Second Layer of Emulsion Surface Protective Layer] Inert gelatin (80 g) was dissolved in water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio: 6)
4/9/20/5/2) 27.5% by mass latex liquid 1
3.2 g of a 5% by mass solution of a fluorine-based surfactant (F-1: potassium salt of N-perfluorooctylsulfonyl-N-propylalanine) (F-2: polyethylene glycol mono (F-2)) N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [average degree of polymerization of ethylene oxide = 1
5]), 32 ml of a 2% by weight aqueous solution of aerosol OT
(American Cyanamid Co.) 5% by mass solution
ml, fine particles of polymethyl methacrylate (average particle size of 0.
7 μm) 4 g, polymethyl methacrylate fine particles (average particle size 4.5 μm) 21 g, 4-methylphthalic acid 1.6
g, phthalic acid 4.8 g, sulfuric acid 4 having a concentration of 0.5 mol / L
4 ml, benzoisothiazolinone 10 mg, total amount 650
g of water and an aqueous solution 445 containing 4% by mass of chromium alum and 0.67% by mass of phthalic acid.
Immediately before coating, a mixture prepared by a static mixer was used as a coating solution for the surface protective layer, and the solution was fed to a coating die at 8.3 ml / m ² . The viscosity of the coating solution was 9 mP with a B-type viscometer at 40 ° C. (No. 1 rotor, 60 rpm).
a · s].

[Preparation of Photothermographic Material] <Preparation of Photothermographic Material-1 (1A to 1G)> An antihalation layer coating solution was coated on the back surface side of the undercoating support with a solid content of a solid fine particle dye. so it becomes 0.04 g / m ^2, also was simultaneously coated as a gelatin coating amount of the back surface protective layer coating solution is 1.7 g / m ^2, and dried, to produce a back layer.

The emulsion layer (photosensitive layer), the intermediate layer, the protective layer first layer, and the protective layer second layer were simultaneously coated on the surface opposite to the back surface in the order of an emulsion layer (photosensitive layer), an intermediate layer, a protective layer first layer, and a protective layer second layer. A sample of the developed photosensitive material was prepared. At this time, the emulsion layer and the intermediate layer were kept at 31 ° C., the first protective layer was kept at 36 ° C., and the second protective layer was kept at 36 ° C.
The layer was thermostated at 37 ° C. The coating amount (g / m ² ) of each compound of each emulsion layer formed using the emulsion layer (photosensitive layer) coating solution-1 (1A to 1G) is as follows.

• Each of organic silver salts A to G 6.19 • Reducing agent or reducing agent complex Listed in Table 2 • Pigment (CI Pigment Blue 60) 0.032 • Organic polyhalogen compound-1 0.46 • Organic polyhalogen compound-2 0.25 Phthalazine compound-1 0.21 SBR latex 11.1 Mercapto compound-1 0.002 Silver halide (as Ag) 0.145

The coating and drying conditions are as follows. The coating was performed at a speed of 160 m / min, the gap between the tip of the coating die and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with ion wind before coating. In the subsequent chilling zone, the coating liquid is cooled by air having a dry-bulb temperature of 10 to 20 ° C., and is transferred in a non-contact type. It was dried with a dry air having a wet bulb temperature of 15 to 21 ° C. After drying, 25 ° C
After adjusting the humidity at 40-60% RH, the membrane surface is
Heated to 0 ° C. After heating, the film surface was cooled to 25 ° C.

The matte degree of the prepared photothermographic material was 550 seconds on the photosensitive layer side and 13 minutes on the back surface in Beck smoothness.
It was 0 seconds. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0.

<< Preparation of Photothermographic Material-2 >> Coating solution-1 for the emulsion layer (photosensitive layer)
(1A to 1G) was changed to Emulsion Layer (Photosensitive Layer) Coating Solution-2, and the photothermographic material was the same as Photothermographic Material-1 except that the yellow dye compound 15 was removed from the antihalation layer. -2 was produced. The coating amount (g / m ² ) of each compound in the emulsion layer at this time is as follows.

-Organic silver salt D 6.19-Pigment (CI Pigment Blue 60) 0.036-Organic polyhalogen compound-2 0.13-Organic polyhalogen compound-3 0.41-Phthalazine compound-1 0.21 SBR latex 11.1 Reducing agent or reducing agent complex Described in Table 2 Mercapto compound-1 0.002 Silver halide (as Ag) 0.10

<< Preparation of Photothermographic Material-3 >> The photothermographic material-1 was coated with an emulsion layer (photosensitive layer) coating solution-1 (1
A to 1G) was changed to an emulsion layer (photosensitive layer) coating solution-2,
Further, the yellow dye compound 15 was removed from the antihalation layer. Further, the fluorine-based surfactants F-1, F-2, F-3 and F-4 of the protective layer second layer and the back surface protective layer were
F-5, F-6, F-7 and F-8 of the same mass, respectively
Changed to Otherwise, the photothermographic material-3 was prepared in the same manner as the photothermographic material-1. The coating amount (g / m ² ) of each compound in the emulsion layer at this time is as follows.

-Organic silver salt D 5.57-Pigment (CI Pigment Blue 60) 0.032-Organic polyhalogen compound-2 0.12-Organic polyhalogen compound-3 0.37-Phthalazine compound-1 0.19 ・ SBR latex 10.0 ・ Reducing agent or reducing agent complex Table 2 ・ Mercapto compound-1 0.002 ・ Silver halide (as Ag) 0.09

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

[0239]

Embedded image

[0240]

Embedded image

[0241]

Embedded image

[0242]

Embedded image

<Evaluation of Photo Performance> Fuji Medical Dry Laser Imager FM-DP L (Max.
(IIIB) 660 nm semiconductor laser output), the photothermographic material obtained above was exposed and thermally developed (1
Four panel heaters set at 12 ° C.-119 ° C.-121 ° C.-121 ° C. for a total of 24 seconds), and the obtained image was evaluated using a densitometer.

The sample obtained above was exposed to a laser, and heat-developed by the above method.
When the value of 1A is set to 100, the relative sensitivity (Δ
S), the minimum density (Dmin), and the maximum density (Dmax) were measured. Further, each sample was stored under the condition of 60 ° C. and 50% relative humidity for 3 days, and the fog density (ΔDmin) of the non-image portion increased during this period was measured. These values are shown in the table.

<Evaluation of Image Preservation> Fuji Medical Dry Laser Imager FM-DP L (60 mW max.)
Exposure and thermal development of the photographic material with (IIIB) output 660 nm semiconductor laser) (112 ° C-119 ° C-121)
4 panel heaters set to ℃ -121 ℃ total 24
Seconds) and then fully illuminated with 70% R.F. H. For 3 hours, sealed in a light-shielding bag, and left at 60 ° C. for 24 hours. At this time, the change ratio of Dmin is shown in the table.

(Example 1) Sample 1 of photothermographic material-1
A to 1G, photothermographic material-2, and photothermographic material-
Table 3 below shows the results of measurement and evaluation of No. 3 by the above evaluation method.

[0247]

[Table 2]

From Table 2 above, it can be seen that the combination of the non-photosensitive organic silver salt particles having a silver behenate content of 90 mol% or more and 100 mol% or less and the use of the reducing agent of the present invention. It was confirmed that the photothermographic material had almost the same sensitivity, little fog over time, and a small rate of change in image storability.

[0249]

According to the present invention, a photothermographic material having high development activity, eliminating delay in development, high sensitivity, low Dmin, excellent image storability, and less fogging during storage. Can be provided.

[Brief description of the drawings]

FIG. 1 is an embodiment of an apparatus for producing a non-photosensitive organic silver salt used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Tank 12 Tank 13 Flow meter 14 Flow meter 15 Pump 16 Pump 17 Pump 18 Mixing device 19 Heat exchanger 20 Tank

Claims (6)

[Claims] 1. A photothermographic material comprising at least one photosensitive silver halide, a reducing agent for silver ions, a binder, and non-photosensitive organic silver salt particles on one surface of a support. The non-photosensitive organic silver salt particles have a silver behenate content of 90 mol% or more and 100 mol% or less, and the reducing agent is a compound represented by the following general formula (I). Photothermographic material. Embedded image In the general formula (I), R ¹¹ and R ¹¹ ′ each independently represent 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 is -S- group or -CHR < ¹³ >-
Represents a group. R ¹³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. X ¹ and X ¹ ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. 2. In the compound represented by the general formula (I), R ¹¹ and R ¹¹ ′ each independently represent a group having 2 to 3 carbon atoms.
A tertiary or tertiary alkyl group, R ¹² and R ¹² ′ are each independently an alkyl group, L is a —CHR ¹³ — group,
R ¹³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms,
The photothermographic material according to claim 1 X ¹ and X ¹ 'is a hydrogen atom. 3. The compound represented by the general formula (I)
And R¹¹And R¹¹'Is independently 2 to 3 carbon atoms
A tertiary or tertiary alkyl group;¹²And R¹²’
Is independently a methyl group or an ethyl group, and L is -CHR¹³−
And R is ¹³Is a hydrogen atom, and X¹And X¹’Is hydrogen
3. The photothermographic material according to claim 1, which is an atom. 4. The photothermographic material according to claim 1, wherein the non-photosensitive organic silver salt particles have a silver behenate content of 94 mol% or more and 100 mol% or less. 5. The non-photosensitive organic silver salt particles have a silver stearate content of 1 mol% or less, and the non-photosensitive organic silver salt particles have a sphere equivalent diameter of 0.05 μm or more and 1 μm or less. The photothermographic material according to claim 1. 6. The photothermographic material according to claim 1, wherein the non-photosensitive organic silver salt particles are scaly particles.