JP2002072404A - Method for producing particulate dispersion of silver salt of organic acid and heat developable photosensitive material using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a particulate dispersion of the silver salt of an organic acid for producing a heat developable photosensitive material having low fog and high sensitivity and less liable to a change in photographic performance with the lapse of time. SOLUTION: The method for producing the particulate dispersion of the silver salt of an organic acid includes (1) a step for introducing one or more ionic surfactants each having an anionic 8-40C hydrophobic group into a reactive solution in an amount of >1 mol% based on the amount of the silver salt of the organic acid during the time befor the start of the formation of the particles to the start of ultrafiltration after the formation of the particles, (2) a step for carrying out ultrafiltration with a membrane having molecular cutoff 10-50 times the molecular weight of the ionic surfactants in such a way that the amount of the ionic surfactants in the reactive solution after ultrafiltration is reduced to 0-1 mol% based on the amount of the silver salt and (3) a step for mechanically dispersing a material obtained by ultrafiltration in the step (2) with a dispersing machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing silver organic acid and a photothermographic material using the same.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand in the medical field to reduce the amount of processing waste liquid from the viewpoint of environmental protection and space saving.
Therefore, a laser imagesetter or laser
There is a need in the art for photothermographic materials for medical diagnostic and photographic applications that can be exposed more efficiently by an imager and can form a sharp black image with high resolution and sharpness. ing. These photothermographic materials can eliminate the use of solution-based processing chemicals and provide a simpler and more environmentally friendly heat development processing system to customers.

[0003] Although there is a similar demand in the field of general image forming materials, medical images require high-quality images with excellent sharpness and granularity due to the need for fine depiction. From the viewpoint, there is a feature that a cool tone image is preferred. 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, thermal image forming systems utilizing organic acid silver salts are described, for example, in US Pat. Nos. 3,152,904 and 3,457,075 and in US Pat. "Thermally Processed Silver Systems" by Klosterboer (Imaging Processes and Materials (Im)
aging Processes and Materials) Neblette 8th edition,
J. Sturge, V.Walworth
h), edited by A. Shepp, Chapter 9, p. 279,
1989). In particular, the photothermographic material generally comprises a catalytically active amount of a photocatalyst (for example, silver halide), a reducing agent, a reducible silver salt (for example, organic acid silver salt), and a toning agent for controlling the color tone of silver as necessary. Is dispersed in a binder matrix. The photothermographic material is exposed to a high temperature (for example, 80
C. or higher) to form a black silver image by an oxidation-reduction reaction between silver halide or a reducible silver salt (which functions as an oxidizing agent) and a reducing agent. 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. A thermal image forming system using these organic acid silver salts can achieve image quality and color tone that are satisfactory as medical images.

The silver source used in such a system is generally a silver salt of an organic acid, and various production methods are known. For example, Japanese Patent Application Laid-Open Nos.
JP-A-9-94619 and JP-A-53-68702.
JP-A-53-31611 discloses a method for preparing an organic acid silver salt in a coexisting solution of water and a poorly water-soluble solvent as disclosed in JP-A-53-31611.
JP-A-54-4117 and JP-A-54-467
A method for preparing an organic acid silver salt in an aqueous solution as described in JP-A-09-0909, JP-A-57-186745 and JP-A-47-18745.
There is a method of preparing an organic acid silver salt in an organic solvent as described in U.S. Pat. No. 9,432 and U.S. Pat. No. 3,700,458. Basically, an organic acid is heated and melted in water at a temperature higher than its melting point, and sodium hydroxide or an alkali metal salt is added with vigorous stirring. Prepared by adding.

In order to obtain a practically usable uniform dispersion using a coating solution containing a silver salt of an organic acid, the silver salt of an organic acid must be finely dispersed without aggregation in a solvent. For this reason, it is necessary to develop a method for dispersing the organic acid silver salt in fine particles. Usually, for example, D. Klosterboer
Method (Imaging Processes and Materials) Neble
tte 8th edition, J.M. Edited by Sturge, V. Walworth and A. Shepp, ninth
Chapter pp. 279 (1989)), a method of forming particles of a hydrophobic organic acid dispersion by filtration, separating the particles by filtration, removing the particles as a solid, and mixing and redispersing a dispersant. Can be

[0007] As a method for dispersing the organic acid silver salt in fine particles, known fine-graining means (for example, high-speed mixer, homogenizer, high-speed impact mill, Banbury mixer, homomixer, kneader, ball mill, vibration Mechanical dispersion methods using ball mills, planetary ball mills, attritors, sand mills, bead mills, colloid mills, jet mills, roller mills, tron mills, high-speed stone mills) are known. As a result, not only can the coating solution with poor coating surface quality be obtained, but also the primary particles of organic acid silver, which originally crystallized as a poorly water-soluble salt, are indiscriminately pulverized. This causes silver nuclei to form on the surface, causing fog to increase.

Therefore, several methods have been proposed in which the primary particles obtained during the reaction of an alkali metal salt solution and a solution containing silver ions are utilized as they are, instead of once taking out the organic acid silver as a solid content and finely dispersing it. ing. For example, JP-A-8-234358 discloses a method of desalinating an organic silver salt dispersion obtained by adding silver nitrate to an aqueous dispersion in which fine particles of an organic acid alkali salt are dispersed by ultrafiltration. Have been. Furthermore, according to this method, a means for increasing the dispersion stability by preliminarily containing a water-soluble protective colloid such as polyvinyl alcohol or gelatin and then performing an ultrafiltration operation is also included. However, the shape of the silver salt of an organic acid obtained by this method is not limited to a needle shape, and it is difficult to control the particle size. And high haze performance has not been stably obtained.

Japanese Patent Application Laid-Open No. 9-127643 discloses a method for directly desalting a fatty acid silver dispersion obtained by simultaneous metered addition of an alkali metal salt solution and a silver nitrate solution using dialysis or ultrafiltration. Have been. According to this method, at least the primary particles obtained at the time of crystallization of the organic acid silver salt can be directly introduced into the photosensitive layer without damaging the particles. However, this does not solve the problem of high viscosity in the above method, and in this regard, it does not provide a means for obtaining a practical uniform dispersion.

Furthermore, Japanese Patent Application Laid-Open No. 9-127463 discloses a method in which a dispersant is used in combination, as in Japanese Patent Application Laid-Open No. 8-234358. The particle shape and particle size are controlled in the presence of a high salt concentration and an organic solvent such as isopropyl alcohol when the particles are formed, and a dispersion having excellent dispersion stability cannot be prepared.

The anionic surfactant has good solubility and adsorptivity to the silver salt of organic acid particles. However, when it is finally contained in the photothermographic material, the hygroscopicity of the photographic material is increased due to ionicity, and the sensitivity is increased. It is known that there is a problem of adversely affecting image quality, gradation, color tone and image storability. As described above, a stable production method for obtaining an organic acid silver salt particle dispersion in which the particles are monodispersed and the particles are uniformly dispersed and has low fog has not been found yet.

[0012]

An object of the present invention is to provide a method for producing an organic acid silver salt which has solved the above-mentioned problems. More specifically, the production of organic acid silver salt particle dispersion for producing a photothermographic material which has low fog when used in a photothermographic material, has high sensitivity and can obtain a high blackening density The task is to provide a method. Another object of the present invention is to provide an organic silver salt particle dispersion for producing a photothermographic material having good photographic properties at the time of development and little deterioration of photographic performance with time. It is a further object of the present invention to provide a photothermographic material having these characteristics.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by the following means, and have completed the present invention. That is, the present invention relates to a method for producing a dispersion of silver salt of an organic acid, comprising the following steps: (1) An ionic surfactant having an anionic hydrophobic group having a carbon number of 8 to 40; A step of introducing at least one kind of the organic acid silver salt into the reaction solution in an amount exceeding 1 mol% from the start of the formation of the silver salt of the organic acid to the ultrafiltration after the formation of the silver salt; Ultrafiltration is performed using a membrane having a molecular weight cutoff of 10 to 50 times the molecular weight of the ionic surfactant, and the amount of the ionic surfactant in the reaction solution after the ultrafiltration is determined to be organic. And (3) mechanically dispersing the ultrafiltrate obtained in step (2) with a disperser. .

According to a preferred embodiment of the present invention, (a) a solution containing silver ions in water or a mixed solution of an organic solvent and water,
And (b) water, a mixed solution of an organic solvent and water, or a solution or suspension containing an alkali metal salt of an organic acid in an organic solvent, further comprising the step of forming the organic silver salt particles. Method;. A step of adding a polymer dispersant, which is nonionic and has a molecular weight of 5 to 50 times the molecular weight cut off of the membrane used for ultrafiltration, after forming the organic acid silver salt particles and before the ultrafiltration operation. The above-mentioned method further comprising: the above-mentioned method, wherein the hydrophilic group of the ionic surfactant is a sulfonate or a sulfate, and is a hydrophilic group having at least one aromatic group; a nonionic polymer dispersant The above method in which the ultrafiltration operation is further performed prior to the addition of the nonionic polymer dispersant, and the electric conductivity when the nonionic polymer dispersant is added is less than 2,000 μS / cm; the concentration of the nonionic polymer dispersant Is from 0.1 to 30% by mass of the organic acid silver solid; one or more dispersants wherein the nonionic polymer dispersant is selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and hydroxypropylcellulose There above method;
And the above method further comprising a step of performing a 2 to 20-fold constant volume dilution after the addition of the nonionic polymer dispersant, and then concentrating the dispersion to a concentration of 10% by mass to 50% by mass.

From another viewpoint, a method for producing a photothermographic material comprising a photosensitive silver halide, a silver salt of an organic acid, a reducing agent for silver ions, and a binder on at least one surface of a support is disclosed. The present invention provides a method characterized by using an organic acid silver salt produced by the above method. According to a preferred embodiment of the present invention, the method comprises photosensitive silver halide and an organic acid silver salt. The binder of the image forming layer to be formed is a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and a relative humidity of 60%.
There is provided a method including a step of applying using a coating liquid in which 0% by mass or more is water. Further, the photothermographic material produced by the above method is also provided by the present invention.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, a numerical range indicated by “to” is a range including a lower limit and an upper limit.
The silver salt of an organic acid which can be used in the present invention is relatively stable to light, but is exposed to 80 ° C. or 80 ° C. It is a silver salt that forms a silver image when heated further. The silver salt of an organic acid may be any organic substance containing a source capable of reducing silver ions. Such non-photosensitive silver salts of organic acids are described in JP-A-10-62899, paragraphs [0048] to [0049] and European Patent Publication EP08037.
No. 63A1, page 18, line 24 to page 19, line 37. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids, are preferred. The carbon number of the long-chain aliphatic carboxylic acid is preferably 10 to 30, more preferably 15 to 28. Preferred examples of the organic acid silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and mixtures thereof.

The shape of the silver salt of an organic acid that can be used in the present invention is not particularly limited. Needle-like, rod-like, flat-plate-like, scale-like, cubic, spherical, potato-like, etc. may be used.
In the present invention, a flaky organic acid silver salt is preferred. In the present specification, the flaky organic silver salt is defined as follows. The silver salt of an organic acid was observed with an electron microscope, and the shape of the silver salt of the organic acid was approximated to a rectangular parallelepiped. The sides of the rectangular parallelepiped were designated as a, b, and c from the shortest side (c is the same as b). Then, calculation is performed using the shorter numerical values a and b, and x is obtained as follows. x = b / a x is obtained for about 200 particles in this manner,
Assuming that the average value x (average), x (average) ≧ 1.5
The one satisfying the relationship of the above is referred to as a scale. Preferably 30 ≧
x (average) ≧ 1.5, more preferably 20 ≧ x (average)
≧ 2.0. By the way, the needle shape is 1 ≦ x (average) <1.5.
It is.

In the scaly particles, a can be regarded as the thickness of tabular particles having a main plane with b and c as sides. The average of a is preferably from 0.01 μm to 0.23 μm, more preferably from 0.1 μm to 0.20 μm. The average of c / b is preferably 1 to 6, more preferably 1.05 to 4, further preferably 1.1 to 3, and particularly preferably 1.1 to 2.

The particle size distribution of the organic acid silver salt is preferably monodispersed. In the monodispersed particle size, 100% or less of the value obtained by dividing the standard deviation of the length of each of the minor axis and major axis by the minor axis and major axis is preferably 100% or less, more preferably 80% or less, and further more preferably. Is 50% or less. The shape of the organic acid silver salt can be determined from a transmission electron microscope image of the organic acid silver salt dispersion. Another method of measuring monodispersity is to determine the standard deviation of the volume-weighted average diameter of the silver salt of an organic acid. The percentage (coefficient of variation) divided by the volume-weighted average diameter is preferably 1
It is at most 00%, more preferably at most 80%, even more preferably at most 50%. As a measuring method, for example, a laser beam is applied to an organic acid silver salt dispersed in a liquid, and an autocorrelation function with respect to a time change of the fluctuation of the scattered light is obtained from a particle size (volume weighted average diameter) obtained. Methods can be mentioned.

The organic acid silver used in the present invention includes an alkali metal salt (such as a Na salt, a K salt and a Li salt) or a suspension of the organic acid described above and a solution containing silver ions. It is prepared by reacting. The alkali metal salt of an organic acid is obtained by treating the above organic acid with an alkali. The silver organic acid can be prepared batchwise or continuously in any suitable vessel. The stirring in the reaction vessel can be performed by any stirring method depending on the required characteristics of the particles. The method for preparing silver organic acid includes a method in which a solution containing silver ions is gradually or rapidly added to a reaction vessel containing an alkali metal salt solution or suspension of an organic acid, a reaction vessel containing a solution containing silver ions. A method of slowly or rapidly adding a previously prepared organic acid alkali metal salt solution or suspension to a reaction vessel, and simultaneously adding a previously prepared solution containing silver ions and an organic acid alkali metal salt solution or suspension to a reaction vessel Any of the above methods can be preferably used.

As the solution containing silver ions and the solution or suspension of the organic acid alkali metal salt, any concentration can be used for controlling the particle size of the prepared organic acid silver salt. It can be added at a rate. As a method for adding a solution containing silver ions and a solution or suspension of an organic acid alkali metal salt, a method of adding at a constant addition rate, an addition method by an arbitrary time function, or a slow addition method can be used. Further, it may be added to the liquid surface or may be added to the reaction solution. In the case of simultaneously adding a previously prepared solution containing silver ions and a solution or suspension of an organic acid alkali metal salt into a reaction vessel, a solution containing silver ions or a solution or suspension of an organic acid alkali metal salt is used. Any of them can be added in advance, but it is preferable to add in advance a solution containing silver ions. The degree of precedence is preferably 0 to 50% by volume of the total amount added, and 0 to 25% by volume.
Is particularly preferred. Further, a method of adding while controlling the pH or silver potential of the reaction solution during the reaction as described in JP-A-9-127643 can also be preferably used.

The pH of a solution containing silver ions or a solution or suspension of an organic acid alkali metal salt to be added can be adjusted according to the required characteristics of the particles. An optional acid or alkali can be added for pH adjustment. Depending on the required characteristics of the particles, for example, the temperature in the reaction vessel can be arbitrarily set for controlling the particle size of the organic silver salt to be adjusted. The metal salt solution or suspension can also be adjusted to any temperature. The organic acid alkali metal salt solution or suspension is preferably heated and kept at 50 ° C. or higher in order to ensure fluidity of the solution.

The organic acid silver used in the present invention is preferably prepared in the presence of a tertiary alcohol. The tertiary alcohol preferably has a total carbon number of 15 or less, and has a total of 10 or less.
Alcohols are particularly preferred. Preferred examples of the tertiary alcohol include tert-butyl alcohol and the like.
The tertiary alcohol may be added at any time during the preparation of the organic acid silver salt. However, it is preferable to add the tertiary alcohol during the preparation of the organic acid alkali metal salt to dissolve the organic acid alkali metal salt before use. The amount of the tertiary alcohol to be used is from 0.01 to the weight ratio of water as the solvent during the preparation of the organic acid silver.
It can be used arbitrarily in the range of 10, but 0.03
The range of ~ 1 is preferable. Hereinafter, the method for producing a silver salt of an organic acid will be described with reference to the use of a tertiary alcohol, but the scope of the present invention is not limited to the case of using a tertiary alcohol.

A water-soluble silver salt can be used as a silver ion source, and silver nitrate is preferable as the water-soluble silver salt. The silver ion concentration in the solution is from 0.03 mol / l to
6.5 mol / L is preferred, and more preferably 0.1 m / L.
ol / l to 5 mol / L, and the pH of this aqueous solution is preferably from 2 to 6, more preferably from 3.5 to 6.

The solution containing silver ions contains 4 carbon atoms.
-6 tertiary alcohols may be contained, in which case, the volume is 70% with respect to the total volume of the solution containing silver ions.
% Or less, preferably 50% or less. The temperature of the solution is preferably from 0 ° C to 50 ° C, more preferably from 5 ° C to 30 ° C. As described later, a solution containing silver ions and a tertiary alcohol aqueous solution of an organic acid alkali metal salt are simultaneously added. In this case, 5 to 15 ° C is most preferable.

Specific examples of the alkali metal of the alkali metal salt of an organic acid include a sodium salt and a potassium salt. The alkali metal salt of an organic acid is prepared, for example, by adding sodium hydroxide or potassium hydroxide to an organic acid. It is prepared by 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 remaining organic acid is 3 mol% to 50 mol%, preferably 3 m
ol% to 30 mol%. Moreover, after adding an alkali more than desired amount, it may be prepared by adding an acid such as nitric acid or sulfuric acid to neutralize excess alkali. Further, the pH can be adjusted according to the required characteristics of the organic acid silver salt. For pH adjustment, any acid or alkali can be used.

Further, an aqueous solution containing silver ions, an aqueous tertiary alcohol solution of an alkali metal salt of an organic acid, or a liquid in a reaction vessel may be used, for example, as shown in the general formula (1) of JP-A-62-65035. Compound and JP-A-62
-Water-soluble group-containing N as described in JP-A-150240
Heterocyclic compounds, inorganic peroxides as described in JP-A-50-101019, sulfur compounds as described in JP-A-51-78319, disulfide compounds as described in JP-A-57-643, and Hydrogen peroxide or the like can be added.

The aqueous tertiary alcohol solution of the organic acid alkali metal salt is preferably a mixed solvent of a tertiary alcohol having 4 to 6 carbon atoms and water in order to obtain a uniform liquid. If the number of carbons exceeds this, the compatibility with water may be reduced, which is not preferable. Of the tertiary alcohols having 4 to 6 carbon atoms, tert-butyl alcohol, which is most compatible with water, is most preferable. Alcohols other than the tertiary alcohol have a reducing property and may be unfavorable because they cause adverse effects when forming the organic acid silver salt. Third of alkali metal salts of organic acids
The amount of the tertiary alcohol used in the alcohol aqueous solution is:
The solvent volume is 3% to 70%, preferably 5% to 50% with respect to the volume of water of the third alcohol aqueous solution.
It is. The concentration of the organic acid alkali metal salt in the aqueous tertiary alcohol solution of the organic acid alkali metal salt is from 7% by mass to 50% by mass, preferably from 7% by mass to 4% by mass.
It is 5% by mass, and more preferably 10% by mass to 40% by mass.

The temperature of the aqueous tertiary alcohol solution of the alkali metal salt of an organic acid to be added to the reaction vessel is set at 50 ° C. for the purpose of keeping the temperature necessary to avoid the crystallization and solidification of the alkali metal salt of the organic acid. C. to 90.degree. C. are preferred, more preferably 60.degree. C. to 85.degree. C., and most preferably 65.degree. In addition, in order to control the temperature of the reaction to be constant, it is preferable to control the temperature to be constant at a certain temperature selected from the above range.

The silver salt of an organic acid preferably used in the present invention is, for example, i) a solution containing silver ions is first made to exist in a reaction vessel in advance, and a tertiary alcohol of an alkali metal salt of an organic acid is added to the solution. A method of single addition of an aqueous solution; ii) a method in which there is a time during the process of simultaneously adding a solution containing silver ions and an aqueous solution of a tertiary alcohol of an organic acid alkali metal salt into a reaction vessel (simultaneous addition method); iii) A method of reacting a silver ion solution with an organic acid alkali metal salt solution; or iv) mixing a silver halide emulsion with the organic acid alkali metal salt solution, adjusting the pH with a sodium hydroxide solution or the like,
It is produced by a method of reacting a silver ion solution. In the present invention, it is preferable to produce a non-photosensitive organic silver salt by the methods of i) to iii), and the simultaneous addition method of ii) in that the average particle size of the organic acid silver salt is controlled and the distribution is narrowed. Is preferred. In that case, it is preferable that 30% by volume or more of the total amount is simultaneously added, and it is more preferable that 50 to 75% by volume be simultaneously added. When any of them is added in advance, it is preferable to add a solution containing silver ions first.

In any case, the liquid in the reaction vessel (as described above, if the solution containing silver ions previously added or the solution containing silver ions previously is not added, Solvent inside)
Is preferably 5 ° C to 75 ° C, more preferably 5 ° C to 75 ° C.
C. to 60C, most preferably 10C to 50C. It is preferable that the temperature is controlled to a certain value selected from the above temperatures throughout the entire process of the reaction.

The temperature difference between the tertiary alcohol aqueous solution of the organic acid alkali metal salt and the liquid in the reaction vessel is preferably from 20 ° C. to 85 ° C., more preferably from 30 ° C. to 80 ° C. In this case, the temperature of the tertiary alcohol aqueous solution of the organic acid alkali metal salt is preferably higher. Thereby, the rate at which the tertiary alcohol aqueous solution of the high-temperature organic acid alkali metal salt is rapidly cooled in the reaction vessel and precipitates in the form of microcrystals, and the rate at which the organic acid silver salt is converted by the reaction with the water-soluble silver salt are preferably controlled, The crystal form, crystal size, and crystal size distribution of the organic acid silver salt can be preferably controlled. At the same time, heat development material,
In particular, the performance as a photothermographic material can be further improved.

For example, a scaly organic silver salt is prepared by reacting a solution containing silver ions with an aqueous tertiary alcohol solution containing an alkali metal salt of an organic acid in a reaction vessel. A step of adding a tertiary alcohol aqueous solution containing a salt) to a method in which the temperature difference between the liquid in the reaction vessel and the tertiary alcohol aqueous solution containing the organic acid alkali metal salt to be added is 20 ° C to 85 ° C. It is preferably manufactured. In this case, the liquid in the reaction vessel is a solution containing silver ions previously placed in the vessel, or a tertiary alcohol aqueous solution containing an organic acid alkali metal salt without preceding the solution containing silver ions. When added simultaneously from the beginning, it is water or a mixed solvent of water and a tertiary alcohol, and even when a solution containing silver ions is added in advance, water or a mixed solvent of water and a tertiary alcohol is used. By maintaining such a temperature difference during the addition of the tertiary alcohol aqueous solution containing the organic acid alkali metal salt, the crystal form and the like of the organic acid silver salt are preferably controlled. 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.

In the present invention, the reaction between a solution containing silver ions and a solution or dispersion of an alkali metal salt of an organic acid is carried out by using at least one kind of anionic, hydrophobic group having 8 to 40 carbon atoms. Performed in the presence of an ionic surfactant. As a solvent of the solution containing silver ions, water or a mixture of water and an organic solvent can be used.As a solvent or dispersion medium of a solution or dispersion of an alkali metal salt of an organic acid,
Water, a mixture of water and an organic solvent, or an organic solvent is used. The above ionic surfactant can be added to one or both of a solution containing silver ions, a solution or dispersion of an alkali metal salt of an organic acid. Alternatively, it may be added to a liquid previously placed in the reaction vessel, or separately, water, a mixture of water and an organic solvent,
Alternatively, it may be dissolved in an organic solvent and added to the reaction system. These addition methods may be arbitrarily combined.

The ionic surfactant is introduced into the reaction solution before the start of particle formation and before ultrafiltration after particle formation. Since the alkali metal salt of a hydrophilic organic acid reacts with silver ions and changes to a hydrophobic silver salt of organic acid, the particles are easily aggregated with each other. It is particularly preferred that the solution is introduced into the reaction system before the addition of the solution is completed.

Preferred surfactants are anionic surfactants that are soluble in the water used for the reaction or in a mixture of water and an organic solvent (these are sometimes referred to as "aqueous media"). As the surfactant, any compound may be used as long as it can disperse the formed organic acid silver salt and has a hydrophobic group having 8 to 40 carbon atoms. The carbon number of the hydrophobic group is more preferably 12 to 40. Examples of the hydrophilic group included in the anionic surfactant include, for example, anionic groups such as carboxylate, sulfate, sulfonate, and phosphate, and include silver ions. From the viewpoint of imparting dispersion stability in a high ionic strength atmosphere due to a by-product salt generated from the reaction between the solution and the solution of the alkali metal salt of the organic acid, the hydrophilic group is preferably a sulfate or a sulfonate,
Those having at least one aromatic group are more preferable.

The amount of the anionic surfactant to be added depends on the type of the surfactant used and the particle size of the organic acid silver salt, and can be selected as appropriate. In an amount exceeding 1 mol% based on the organic silver salt. In order to have an adsorption rate that can follow the formation rate of organic acid silver salt particles, the critical micelle concentration should be 5 to 10
It is preferably 0 times, and the critical micelle concentration is 20 to 8 times.
0 times is more preferable.

In the method of the present invention, the above-mentioned anionic surfactant is contained in an amount exceeding 1 mol% based on the amount of the organic silver salt until the prepared dispersion of organic acid silver particles is subjected to ultrafiltration. However, after the ultrafiltration, the concentration is adjusted to 1 mol% or less. As described above, when the anionic surfactant is finally contained in the photothermographic material, the hygroscopicity of the photosensitive material increases due to ionicity, and sensitivity, gradation,
Further, the color tone and image storability may be adversely affected. For this reason, the residual amount of the ionic surfactant after the ultrafiltration treatment is independent of the amount added for dispersion stability,
The amount must not affect photographic performance. In the present invention, the amount of the anionic surfactant in the organic acid silver particle dispersion is preferably 1 mol% or less, more preferably 0.5 mol% or less per 1 mol of the organic acid silver after ultrafiltration. . Adjustment of the residual amount of anionic surfactant,
For example, a so-called constant solution dilution operation can be performed under appropriate conditions by adding pure water in an amount corresponding to the solution amount of the anionic surfactant that has passed through the ultrafiltration membrane. The remaining amount of the ionic surfactant can be arbitrarily changed.

In the present invention, a nonionic polymer dispersant can be further used in the preparation of the dispersion of the silver salt of an organic acid. As the nonionic polymer dispersant to be used in combination, for example, a silver salt of an organic acid can be dispersed, and a by-product salt generated by a reaction between a solution containing silver ions and a solution of an alkali metal salt of an organic acid can be removed. Those having an ultrafiltration membrane having a molecular weight cutoff of 5 to 10 times that used for the salt can be used. Among the above dispersants, a nonionic polymer dispersant soluble in a reaction aqueous solvent can be suitably used.
As such a dispersant, polyvinyl alcohol, polyvinyl pyrrolidone, and hydroxypropyl cellulose are preferably used.

The concentration of the nonionic polymer dispersant is 0.1 to 30% by mass, especially 0.5%, based on the organic acid silver salt (solid content).
The range is preferably from 30 to 30% by mass. The time of addition of the nonionic polymer dispersant is not particularly limited, but it should be after the reaction of the organic acid silver salt and before the desalting operation in order to prevent the inhibition of the organic acid silver salt reaction. Is preferred. In a more preferred embodiment, desalting is performed by ultrafiltration, and the nonionic polymer dispersant can be added after the electric conductivity of the organic acid silver dispersion is reduced. The electric conductivity at this time is preferably 2,000 μS / cm or less. In addition, it is preferable that after the addition of the nonionic polymer dispersant, the dispersion is concentrated to 10 to 50% by mass after performing a 2 to 20-fold constant volume dilution.

As the ultrafiltration method, for example, a method used for desalting / concentrating a silver halide emulsion can be applied. The ultrafiltration method is described in Research Disclosure No. 10 208 (1).
972), No. 13 122 (1975) and No. 13
16 351 (1977). The pressure difference and flow rate, which are important as operating conditions, are described in “Handbook for Membrane Utilization Technology” by Haruhiko Oya, Koshobo Publishing (1978),
p. Although it can be selected with reference to the characteristic curve described in H.275, it is necessary to find optimal conditions for suppressing the aggregation and fogging of particles when processing the target organic acid silver dispersion. 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. May be mixed or added directly to the organic acid silver dispersion. In the high salt concentration atmosphere at the beginning of the desalting operation and during the presence of an organic solvent such as a tertiary alcohol, the silver salt of the organic acid is in an easily agglomerated state, and thus is anionic and
The concentration of the ionic surfactant having a hydrophobic group having 40 carbon atoms is desirably maintained at 5 to 100 times the critical micelle concentration. Specifically, the concentration of the surfactant that leaks out is quantified by spectral absorption or liquid chromatography, and a solution having the same concentration may be continuously added as a replenisher, or a higher concentration of the surfactant may be added. The activator solution may be added intermittently.

Further, since the silver salt of an organic acid is extremely hydrophobic, flocculation may remarkably proceed due to a liquid feeding operation or a shearing field or a pressure field when passing through an ultrafiltration membrane.
Furthermore, under the high ionic strength atmosphere at the beginning of the desalination operation,
The surface charge of the silver salt of the organic acid is shielded, and the silver salt is easily aggregated. The above ionic surfactant different from the anionic surfactant previously added to alleviate this state (that is, another ionic surfactant having an anionic hydrophobic group having 8 to 40 carbon atoms) ) During the desalting operation is also a preferred embodiment of the present invention. As for the addition method, the concentration of the leaking surfactant is quantified by spectral absorption or liquid chromatography as described above, and a solution having the same concentration may be added continuously as a replenisher, or High concentration surfactant solutions may be added intermittently.

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 and the like are commercially available from Asahi Kasei Corporation, Daicel Chemical Co., Ltd., Toray Co., Ltd., Nitto Denko Co., Ltd., and from the viewpoint of total membrane area and washability, spiral type or hollow fiber type is preferable. . Also,
The molecular weight cutoff as an index of the threshold value of the component capable of permeating the membrane is determined by the ionic surfactant used (ionic surfactant having an anionic hydrophobic group having 8 to 40 carbon atoms). Agent) must be determined from the molecular weight of the agent.
Since the molecular weight of the anionic surfactant typically used in the present invention is 150 to 1,000, it is 10 times that of 1.5 to 1.5.
The thing of 00-50,000 or more is used.

When the molecular weight cut off of the ultrafiltration membrane is unknown,
The anionic surfactant solution to be used may be filtered, and the rejection may be calculated from the concentration of the surfactant leaking into the permeate.
Assuming that the stock concentration of the anionic surfactant is Ci and the concentration leaking into the permeate is Co, the rejection R of the ultrafiltration membrane is defined by R = (Ci-Co) / Ci × 100 [%]. You. The rejection in the method of the invention is 50%
Less than is preferred.

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

The prepared dispersion is stored with stirring for the purpose of suppressing sedimentation of fine particles during storage, or stored in a highly viscous state (for example, in a jelly state using gelatin) with a hydrophilic colloid. You can also do.
Further, a preservative can be added for the purpose of preventing the propagation of various bacteria during storage.

The dispersion of the silver salt of an organic acid in the present invention is prepared as a dispersion containing at least a silver salt of an organic acid and water. The ratio of the silver salt of organic acid to water is not particularly limited, but when considering the formation of an efficient coating film, the production speed determined by the rheological properties for stable coating and the amount of dry moisture. It can be appropriately determined in consideration of such factors. In the method of the present invention, the electrical conductivity is 20 μS / cm or more and 300 μ
After reaching below S / cm, the concentration of the dispersion can be concentrated to 10 to 50% by weight, preferably 10 to 30% by weight.

In the present invention, Ca, Mg, Ce, A
It is preferable to add a metal ion selected from 1, Zn, and Ba in the form of a water-soluble salt that is not a halide. Specifically, it is preferable to add in the form of nitrate or sulfate.
The timing of adding the metal ion selected from Ca, Mg, Ce, Al, Zn, and Ba is not particularly limited, and the addition of the organic acid silver salt preparation into the liquid, the prior addition to the reaction solution, the organic acid silver salt It may be at any time during or immediately after the application, such as during or immediately after the formation, or before or after the preparation of the coating solution. The addition amount is preferably from 10 ^-3 to 10 ^-1 mol, more preferably from 5 x 10 ^{-3 to} 5 x 10 ^-2 mol, per mol of the organic acid silver salt.

Regarding the mixing method and the mixing conditions of the separately prepared photosensitive silver halide and organic acid silver salt, the prepared silver halide particles and organic acid silver salt are mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, and the like. , A method of mixing with a vibration mill, a homogenizer, or the like, or a method of preparing a silver salt of an organic acid by mixing photosensitive silver halide prepared at any timing during the preparation of the silver salt of an organic acid. There is no particular limitation as long as the effects of the present invention are sufficiently exhibited. However, as described later, it is desirable to finely disperse the prepared organic acid silver salt in water and add silver halide grains thereto.

The silver salt dispersion of an organic acid is mechanically dispersed by a dispersing machine within a range that does not cause deterioration of photographic properties. As a dispersion method, it is preferable to obtain a water dispersion of the organic acid silver salt, convert the dispersion to a high-speed flow at high pressure, and then re-disperse by lowering the pressure to obtain a fine water dispersion. In this case, the dispersion medium is preferably only water, but may contain an organic solvent as long as it is 20% by mass or less.

For the dispersion apparatus and the technique used for carrying out the redispersion method as described above, see, for example, “Dispersion Rheology and Dispersion Technique” (Toshio Kajiuchi, Hiroki Usui)
Author, 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, p184-1
85), JP-A-59-49832, U.S. Pat.
No. 533254, Japanese Unexamined Patent Application Publication No. 8-137404, Japanese Unexamined Patent Application Publication No. 8-238848, Japanese Unexamined Patent Application Publication No. 2-261
No. 525, JP-A-1-94933, etc., the redispersion method used in the present invention is to pressurize an aqueous dispersion containing at least a silver salt of an organic acid with a high-pressure pump or the like and feed it into a pipe. Through a narrow slit provided in the pipe,
Thereafter, it is preferable that the dispersion is finely dispersed by causing a sharp pressure drop in the dispersion.

When a photosensitive silver halide salt is present in the dispersion of the organic acid silver salt, fog may increase and the sensitivity may be remarkably reduced. Therefore, the photosensitive silver halide salt is not substantially contained at the time of dispersion. Is more preferable. The content of the photosensitive silver halide in the aqueous dispersion to be dispersed is 0.1 mol% or less based on 1 mol of the organic acid silver salt in the liquid, and the active addition of the photosensitive silver halide is not performed. It is desirable.

It is preferable that the prepared silver salt of an organic acid is finely dispersed in an aqueous solvent and then mixed with an aqueous solution of a photosensitive silver halide salt to be supplied as a coating solution for a photosensitive image forming layer. When a photothermographic material is prepared using such a coating liquid, a haze is low, and a low-fogging and high-sensitivity photothermographic material can be obtained. On the other hand, when a photosensitive silver halide salt coexists when the organic acid silver salt is finely dispersed by being converted into a high-speed stream under high pressure, fog increases and the sensitivity may be significantly reduced. It is desirable that the aqueous dispersion that is converted after being converted into a high-speed one does not substantially contain a photosensitive silver halide salt. When an organic solvent is used instead of water as a dispersion medium, haze is increased, fog is increased, and sensitivity may be easily reduced. On the other hand, when the conversion method of converting a part of the organic acid silver salt in the dispersion liquid into the photosensitive silver halide salt is used instead of the method of mixing the aqueous solution of the photosensitive silver halide salt, the sensitivity may be reduced. .

The particle size (volume-weighted average diameter) of the organic acid silver salt solid fine particle dispersion is determined, for example, by irradiating the solid fine particle dispersion dispersed in a liquid with a laser beam, and autocorrelating the scattered light fluctuation with time. It can be obtained from the particle size (volume weighted average diameter) obtained by obtaining the function. A solid fine particle dispersion having an average particle size of 0.05 μm to 10.0 μm is preferred. More preferably, the average particle size is 0.1 μm to 5.0 μm or less, and still more preferably, the average particle size is 0.1 μm to 2.0 μm.

The mixing ratio between the organic acid silver salt and the photosensitive silver halide salt can be selected according to the purpose, but the ratio of the photosensitive silver halide salt to the organic acid silver salt is preferably in the range of 1 to 30 mol%. More preferably, it is in the range of 3 to 20 mol%, particularly preferably 5 to 15 mol%. 2 when mixing
Mixing two or more kinds of aqueous dispersions of organic acid silver salts and two or more kinds of aqueous dispersions of photosensitive silver halide salts is a method preferably used for controlling photographic characteristics. Organic silver salts can be used in a desired amount in the photothermographic material, it is preferably 0.1-5 g / m ² as silver amount, more preferably 1
３3 g / m ² .

When the organic silver salt is dispersed, coexistence of a photosensitive silver salt increases fog and significantly lowers sensitivity. Therefore, it is more preferable that the photosensitive silver salt is not substantially contained at the time of dispersion. The amount of the photosensitive silver salt in the aqueous dispersion to be dispersed is 0.1 mol% or less based on 1 mol of the organic acid silver salt in the liquid, and it is preferable not to actively add the photosensitive silver salt. .

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 can be appropriately selected according to the purpose. . For example, the ratio of photosensitive silver salt to organic silver salt is 1
~ 30 mol% is preferred, more preferably 3 ~ 20 mol%, especially 5 ~
A range of 15 mol% is preferred. Mixing two or more aqueous dispersions of organic silver salts with two or more aqueous dispersions of photosensitive silver salts during mixing is a method preferably used for adjusting photographic characteristics. Organic silver salts can be used in a desired amount, preferably 0.1-5 g / m ² as silver amount, more preferably 1 to 3
g / m ² .

The photothermographic material of the present invention preferably contains a reducing agent for an organic silver salt. The reducing agent for the organic silver salt may be any substance (preferably an organic substance) that reduces silver ions to metallic silver. Such a reducing agent is
Paragraph Nos. 0043 to 0045 of JP-A-11-65021
And page 7 of EP-A-0 076 364 A1
It is described from line 4 to page 12, line 12. In the present invention, the reducing agent is preferably a bisphenol reducing agent, and more preferably a compound represented by the following general formula (I).

[0060]

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[0061] (In the general formula (I), R ¹ and R ¹ 'are .R ² and represents an alkyl group having 1 to 20 carbon atoms each independently
R ² ′ each independently represents a hydrogen atom or a substituent that can be substituted on a benzene ring. L is -S- group or -CH (R ³⁾ - represents a group. R ³
Represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. X
And X ′ each independently represent a hydrogen atom or a group that can be substituted on a benzene ring. )

R ¹ and R ¹ ′ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and the substituent of the alkyl group is not particularly limited, but is preferably an aryl group, Hydroxy group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, sulfonamide group, sulfonyl group, phosphoryl group,
Examples include an acyl group, a carbamoyl group, an ester group, and a halogen atom.

R ² and R ² ′ are each independently a hydrogen atom or a substituent that can be substituted on a benzene ring, and X and X ′ are each independently a hydrogen atom or a group that can be substituted on a benzene ring. Preferred 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 —CH (R ³ ) — group. R ³ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have a substituent. Specific examples of the unsubstituted alkyl group for R ³ include, for example, methyl group, ethyl group, propyl group, butyl group, heptyl group, undecyl group, isopropyl group, 1-ethylpentyl group,
And a 2,4,4-trimethylpentyl group.
Examples of the substituent for the alkyl group are the same as those of the substituent of R ^1, for example, a halogen atom, an alkoxy group, an alkylthio group,
Aryloxy group, arylthio group, acylamino group,
Examples include a sulfonamide group, a sulfonyl group, a phosphoryl group, an oxycarbonyl group, a carbamoyl group, and a sulfamoyl group.

R ¹ and R ¹ ′ preferably have 3 to 3 carbon atoms.
15 secondary or tertiary alkyl groups, specifically, isopropyl, isobutyl, t-butyl, t-amyl, t-octyl, cyclohexyl, cyclopentyl, 1-methyl Examples include a cyclohexyl group and a 1-methylcyclopropyl group. R ¹
And R ¹ ′ more preferably include a tertiary alkyl group having 4 to 12 carbon atoms, and among them, a t-butyl group, a t-amyl group, and a 1-methylcyclohexyl group are more preferable, and a t-butyl group is more preferable. Most preferred.

R ² and R ² ′ preferably have 1 to 2 carbon atoms.
0 alkyl group, specifically methyl, ethyl, propyl, butyl, isopropyl, t-butyl, t-amyl, cyclohexyl, 1-methylcyclohexyl, benzyl, methoxymethyl And a methoxyethyl group. More preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group and a t-butyl group. X and X 'are preferably a hydrogen atom, a halogen atom, and an alkyl group, and more preferably a hydrogen atom.

L is preferably a —CH (R ³ ) — group. R ³ is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and the alkyl group is preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or a 2,4,4-trimethylpentyl group. Particularly preferred as R ³ is a hydrogen atom, a methyl group, an ethyl group or a propyl group.

When R ³ is a hydrogen atom, R ² and R ² ′ are preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group. If R ³ is a primary or secondary alkyl group having 1 to 8 carbon atoms, it is preferred that R ² and R ² 'is a methyl group. As the primary or secondary alkyl group having 1 to 8 carbon atoms for R ^3, 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.

Specific examples of the compound represented by formula (I) used in the present invention are shown below, but it should not be construed that the invention is limited thereto.

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[0071]

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[0072]

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[0073]

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In the present invention, the amount of the reducing agent added is 0.01 to 5.
It is preferably 0 g / m ^2, and more preferably 0.1 to 3.0 g / m ^2. It is preferably contained in an amount of 5 to 50% by mole relative to 1 mole of silver on the surface having the image forming layer, and more preferably 10 to 40%.
More preferably, it is contained in mol%. The reducing agent is preferably contained in the image forming layer.

To incorporate a reducing agent into the photosensitive material,
The reducing agent may be contained in the coating liquid by any method such as a solution form, an emulsified dispersion form, a solid fine particle dispersion form, and well-known emulsified dispersion methods include dibutyl phthalate, tricresyl phosphate, and glyceryl. A method in which an oil such as triacetate or diethyl phthalate or an auxiliary solvent such as ethyl acetate or cyclohexanone is used to dissolve the reducing agent and mechanically produce an emulsified dispersion is used.

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 vibration ball mill, a sand mill, a jet mill, a roller mill, or ultrasonic waves to obtain a solid dispersion. The method of making is mentioned. At that time, 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. 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. When the reducing agent in the present invention has an aromatic hydroxyl group (-OH), particularly in the case of the above-mentioned bisphenols, a non-reducing compound having a group capable of forming a hydrogen bond with these groups Is preferably used in combination. 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> NR (R is a substituent other than H)), and a urethane group. (However, it has no> NH group and is blocked like> NR (R is a substituent other than H).), A ureido group (however, does not have a> NH group, and> NR (R is H
Other substituents). ). In the present invention, a particularly preferred compound having a hydrogen bond is a compound represented by the following general formula (II).

[0078]

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In the general formula (II), R ¹¹ to R ¹³ each independently represent an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group or a heterocyclic group. It may have a substituent.
When R ¹¹ to R ¹³ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, Examples include an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, and a phosphoryl group. Preferred substituents are an alkyl group and an aryl group, specifically, a methyl group, an ethyl group, an isopropyl group, and a t-butyl group. Group, t-octyl group, phenyl group,
Examples thereof include a 4-alkoxyphenyl group and a 4-acyloxyphenyl group.

Examples of the alkyl group for R ¹¹ to R ¹³ include a methyl group, an ethyl group, a butyl group, an octyl group,
Examples thereof include a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a phenethyl group, and a 2-phenoxypropyl group. Examples of the aryl group include a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group, a 4-t-octylphenyl group, a 4-anisidyl group, and a 3,5-dichlorophenyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a butoxy group, an octyloxy group,
Examples include an ethylhexyloxy group, a 3,5,5-trimethylhexyloxy group, a dodecyloxy group, a cyclohexyloxy group, a 4-methylcyclohexyloxy group, and a benzyloxy group. Examples of the aryloxy group include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, a biphenyloxy group, and the like. As the amino group, a dimethylamino group, a diethylamino group, a dibutylamino group,
Dioctylamino group, N-methyl-N-hexylamino group, dicyclohexylamino group, diphenylamino group,
And an N-methyl-N-phenylamino group.

As R ¹¹ to R ¹³ , an alkyl group, an aryl group, an alkoxy group and an aryloxy group are preferred.
From the viewpoint of the effect of the present invention, it is preferable that at least one of R ¹¹ to R ¹³ is an alkyl group or an aryl group, and it is more preferable that at least two of them are an alkyl group or an aryl group. Further, it is preferable that R ¹¹ to R ¹³ are the same group in that they can be obtained at low cost.

Specific examples of the compound represented by formula (II) are shown below, but it should not be construed that the invention is limited thereto.

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[0084]

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[0085]

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[0086]

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The compound of the general formula (II) can be contained in a coating solution in the form of a solution, an emulsified dispersion or a solid-dispersed fine particle dispersion as in the case of the reducing agent, and used in a light-sensitive material. The compound used in the present invention forms a hydrogen bonding complex with a compound having a phenolic hydroxyl group or an amino group in a solution state, and depending on the combination of the reducing agent and the compound of the general formula (II), the compound may be in a crystalline state. Can be isolated. 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, a method in which the reducing agent and the compound of the formula (II) are mixed in a powder form, and a suitable dispersant is used to form a complex at the time of dispersion with a sand grinder mill or the like can also be preferably used. The compound of the general formula (II) is preferably used in the range of 1 to 200 mol%, more preferably in the range of 10 to 150 mol%, and still more preferably in the range of 30 to 100 mol%, based on the reducing agent. It is.

The photosensitive silver halide is not particularly limited as a halogen composition, and silver chloride, silver chlorobromide, silver bromide, silver iodobromide, and silver iodochlorobromide can be used. The distribution of the halogen composition in the grains may be uniform, the halogen composition may change stepwise, or may change continuously. Further, silver halide grains having a core / shell structure can be preferably used. The preferred structure is a two- to five-layer structure, and more preferably, a core / shell particle having a two- to four-layer structure can be used. A technique for localizing silver bromide on the surface of silver chloride or silver chlorobromide grains can also be preferably used.

Methods for forming light-sensitive silver halide are well known in the art, for example, Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,45.
The method described in No. 8 can be used, but specifically, a photosensitive silver halide is prepared by adding a silver supply compound and a halogen supply compound in gelatin or another polymer solution, Thereafter, a method of mixing with an organic silver salt is used. Also, the method described in paragraphs 0217 to 0224 of JP-A-11-119374,
The methods described in Japanese Patent Application Nos. 11-98708 and 11-84182 are also preferable.

The grain size of the photosensitive silver halide is preferably small for the purpose of suppressing white turbidity after image formation, specifically, 0.20 μm or less, more preferably 0.01 μm or less.
It is from μm to 0.15 μm, more preferably from 0.02 μm to 0.12 μm. 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).

The shapes of the silver halide grains are cubic,
Octahedral, tabular particles, spherical particles, rod-like particles, potato-like particles and the like can be mentioned. In the present invention, cubic particles are particularly preferable. 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 grain is not particularly limited, but the spectral sensitizing efficiency when the spectral sensitizing dye is adsorbed is high. preferable. The ratio is preferably 50% or more, 6
5% or more is more preferable, and 80% or more is further preferable. The ratio of the [100] plane of the Miller index is determined by T. Tani; J. Imagin, which utilizes the dependence of the adsorption of the sensitizing dye on the [111] and [100] planes.
g Sci., 29, 165 (1985).

In the present invention, silver halide grains having a hexacyano metal complex present on the outermost surface of the grains are preferred. As hexacyano metal complexes, [Fe (CN) ₆ ] ^4- , [Fe (CN) ₆ ] ^3- ,
[Ru (CN) ₆ ] ^4- , [Os (CN) ₆ ] ^4- , [Co (CN) ₆ ] ^3- , [Rh (C
^{_{N) 6] 3-, [Ir}} (CN) 6] 3-, [Cr (CN) 6] 3 -, and the like ^{_{3- [Re (CN) 6]}} . In the present invention, a hexacyano Fe complex is preferred.

The hexacyano metal complex is present in the form of ions in an aqueous solution, so that the counter cation is not important. However, the hexacyano metal complex is easily miscible with water and is compatible with sodium ion and potassium ions which are suitable for the precipitation operation of a silver halide emulsion. Use of alkali metal ions such as ions, rubidium ions, cesium ions, and lithium ions, ammonium ions, and alkylammonium ions (for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetra (n-butyl) ammonium ion) Is preferred.

The hexacyano metal complex may be used in combination with a water-miscible organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides, etc.) or gelatin. And can be added as a mixture. The amount of hexacyano metal complex added is per mole of silver.
The amount is preferably from 1 × 10 ⁻⁵ mol to 1 × 10 ⁻² mol, 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 the silver nitrate aqueous solution used for grain formation is followed by sulfur sensitization, selenium sensitization and tellurium sensitization. Is added directly before the completion of the preparation 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 may be started after adding 96% by mass of the total amount of silver nitrate added for forming particles, more preferably started after adding 98% by mass, After adding 99 mass%, it is especially preferable.

When these hexacyano metal complexes are added after the addition of an aqueous silver nitrate solution immediately before the completion of grain formation, they can be adsorbed on the outermost surface of silver halide grains, and most of them are hardly soluble in silver ions on the grain surface. Forms salt. Since the silver salt of hexacyanoiron (II) 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.

The photosensitive silver halide grains can contain a metal or a metal complex of Group 8 to Group 10 of the periodic table (showing Groups 1 to 18). Group 8-Periodic Table
Rhodium, ruthenium and iridium can be preferably cited as the group 10 metal 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-7-225449,
No. 5021, paragraphs 0018 to 0024, and JP-A-11-119374, paragraphs 0227 to 0240.

Further, metal atoms (for example, [Fe (CN) ₆ ]) which can be contained in the silver halide grains used in the present invention.
^4- ), desalting and chemical sensitization of silver halide emulsions are described in JP-A-11-84574, paragraphs 0046-0050, JP-A-11-84574.
-65021, paragraphs 0025 to 0031, and JP-A-11-119374, paragraphs 0242 to 0250.

Various gelatins can be used as the gelatin contained in the photosensitive silver halide emulsion used in the present invention. 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.

The sensitizing dye applicable to the present invention is a sensitizing dye capable of spectrally sensitizing silver halide grains in a desired wavelength range when adsorbed on silver halide grains, and has a spectral sensitivity suitable for the spectral characteristics of an exposure light source. The sensitizing dye to be used can be advantageously selected. For sensitizing dyes and addition methods, see
-65021, paragraphs 0103 to 0109, JP-A-10-186572
Compound represented by the general formula (II), JP-A-11-119374
The dye represented by the general formula (I) and paragraph No. 0106,
U.S. Pat.Nos. 5,510,236 and 3,871,887, dyes described in Example 5, JP-A-2-96131, JP-A-5
No. 9-48753, dye disclosed in European Patent Publication No. 0
No. 803764A1, page 19, line 38 to page 20, page 35
And Japanese Patent Application Nos. 2000-86865 and 2000-102560. These sensitizing dyes may be used alone or in combination of two or more. In the present invention, the time when the sensitizing dye is added to the silver halide emulsion is preferably after the desalting step and before coating, and more preferably after desalting and before the start of chemical ripening. The addition amount of the sensitizing dye in the present invention can be a desired amount in accordance with the sensitivity and fogging performance, but is preferably 10 ^-6 to 1 mol, more preferably 1 mol per mol of silver halide in the photosensitive layer. Is 10 ^-4 to 10 ^-1 mol.

In the photothermographic material, a supersensitizer can be used to improve the spectral sensitization efficiency.
As supersensitizers, EP-A-587,338,
U.S. Pat.Nos. 3,877,943, 4,873,184, JP-A-5-341432, JP-A-11-109547 and JP-A-10-
The compounds described in JP-A-111543 and the like can be mentioned.

The photosensitive silver halide grains may be prepared by a sulfur sensitization method,
Chemical sensitization by a selenium sensitization method or a tellurium sensitization method is preferable. As the compounds preferably used in the sulfur sensitization method, selenium sensitization method, and tellurium sensitization method, known compounds, for example, compounds described in JP-A-7-128768 and the like can be used. In the present invention, in particular, tellurium sensitization is preferable, and JP-A-11-65021, paragraph number 00
Compounds described in the literature described in No. 30 and compounds represented by formulas (II), (III) and (IV) in JP-A-5-313284 are more preferred.

Chemical sensitization can be performed at any time after grain formation and before coating. After desalting, (1) before spectral sensitization,
Any of (2) simultaneous with spectral sensitization, (3) after spectral sensitization, (4) immediately before coating, and the like may be used. In particular, it is preferable to perform chemical sensitization after spectral sensitization. Sulfur used in the present invention, selenium and the amount of tellurium sensitizer, silver halide grains to be used may be appropriately selected by a chemical ripening condition and the like, per 1 mol of silver halide 10 ^-8 to 10 ^-2 mol, Preferably 1
About ^0-7 to ^10-3 mol can be used. The conditions for the chemical sensitization are not particularly limited, but the pH is 5 to 8, p
Ag is about 6 to 11, and temperature is about 40 to 95 ° C. European Patent Publication No. 293,91 includes silver halide emulsions.
A thiosulfonate compound may be added by the method disclosed in Japanese Patent Publication No. 7 (1999).

The photosensitive silver halide emulsion in the photothermographic material may be only one kind or two or more kinds (for example, those having different average grain sizes, those having different halogen compositions, those having different crystal habits, those having different chemical habits, and those having different chemical habits). And the like having different feeling conditions) may be used in combination. The gradation can be adjusted by using a plurality of photosensitive silver halides having different sensitivities. Techniques relating to these include JP-A-57-119341 and JP-A-53-119341.
No. 106125, No. 47-3929, No. 48-55730,
Nos. 46-5187, 50-73627 and 57-150841. The sensitivity difference between each emulsion
It is preferable to have a difference of 0.2 logE or more.

[0105] The addition amount of the photosensitive silver halide is preferably 0.03~0.6g / m ² as the amount of coated silver per photosensitive material 1 m ^2, more preferably from 0.05 to 0.4 g / m ^2, Most preferably, it is 0.1 to 0.4 g / m ² . Organic silver salt
For 1 mole, the photosensitive silver halide is 0.01 mole to 0.5 mole.
Mol is preferable, and 0.02 mol to 0.3 mol is more preferable.

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 vibrator. Mills, a method of mixing with a homogenizer, etc., or 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, etc. There is no particular limitation on the mixing method and mixing conditions as long as the effect is sufficiently exhibited. 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 timing of addition of the silver halide used in the present invention to the coating solution for the image forming layer is preferably from 180 minutes to immediately before coating, and preferably from 60 minutes to 10 seconds before coating. Is not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, 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, by N. Harnby, MF Edwards, AW Nienow, Takahashi Translated by Koji “Liquid mixing technology” (Nikkan Kogyo Shimbun, 1989)
There is a method using a static mixer or the like described in Chapter 8 or the like.

The binder of the image forming layer used in the present invention may be any polymer. Suitable binders are transparent or translucent and are generally colorless. For example, natural resins and polymers and copolymers, synthetic resins and polymers and copolymers, and other film-forming media, for example,
Gelatins, rubbers, poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrate, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid) s, poly (methyl methacrylic acid) ), Poly (vinyl chloride) s, 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 (ester)
, Poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), poly (olefin), cellulose ester, poly (amide) ). The binder may be coated from water or an organic solvent or emulsion.

An image forming layer containing a photosensitive silver halide and an organic acid silver salt has a binder of 25 ° C. and a relative humidity of 60%.
It is preferred that the image forming layer is coated with a coating liquid having a water content of 2% by mass or less and a water content of 30% by mass or more of the solvent. It is also preferable that the binder of the image forming layer is soluble or dispersible in an aqueous solvent (aqueous solvent). The most preferred form has an ionic conductivity of 2.
It is prepared so as to be 5 mS / cm or less. As such a preparation method, there is a method of purifying using a separation functional membrane after synthesizing a polymer.

The aqueous solvent in which the polymer is soluble or dispersible is water or a mixture of water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethyl acetate; and dimethylformamide. Note that the term “aqueous solvent” is used herein even in a system in which the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

The “equilibrium moisture content at 25 ° C. and 60% relative humidity” refers to the weight W1 of the polymer that is in a moisture-conditioning equilibrium in an atmosphere of 25 ° C. and a relative humidity of 60%, and the weight of the polymer that is completely dried at 25 ° C. It can be expressed as follows using W0. Equilibrium water content at 25 ° C and 60% relative humidity = [(W1-W0) / W0] x 100 (% by mass) For the definition and measurement method of water content, see, for example, Polymer Engineering Course 14, (Edited by Molecular Society, Jinjinshokan)
Can be referred to.

The equilibrium water content of the binder polymer at 25 ° C. and a relative humidity of 60% is preferably 2% by mass or less, more preferably 0.01% by mass to 1.5% by mass, further preferably 0.02% by mass to 1% by mass. desirable.

As the binder polymer, a polymer dispersible in an aqueous solvent is particularly preferred. 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, all of which are preferable. The average particle size of the dispersed particles is preferably in the range of 1 to 50,000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

Preferred embodiments of the polymer dispersible in an aqueous solvent include acrylic polymers and poly (ester).
And hydrophobic polymers such as rubbers (eg SBR resin), poly (urethane) s, poly (vinyl chloride) s, poly (vinyl acetate) s, poly (vinylidene chloride) s, poly (olefin) s Can be. These polymers may be any of a linear polymer, a branched polymer, and a cross-linked polymer, and may be a so-called homopolymer in which a single monomer is polymerized. Further, a copolymer obtained by polymerizing two or more kinds of monomers may be used. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of these polymers is the number average molecular weight
5000-1000000, preferably 10000-200000. If the molecular weight is too small, the mechanical strength of the emulsion layer may be insufficient, and if it is too large, the film-forming properties may be poor.

Specific examples of the preferred polymer latex include the following. In the following, the raw material monomers are used, and the numerical value in parentheses is% by mass, and the molecular weight is the number average molecular weight. P-1; -MMA (70) -EA (27) -MAA (3)-latex (molecular weight 3700
0) Latex of P-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-(molecular weight 40000) P-3; -St (50) -Bu (47) -MAA ( 3)-latex (molecular weight 4500
0) P-4; -St (68) -Bu (29) -AA (3)-latex (MW 60000) P-5; -St (71) -Bu (26) -AA (3)-latex (Molecular weight 60000) P-6; -St (70) -Bu (27) -IA (3)-latex (molecular weight 12000
0) Latex of P-7; -St (75) -Bu (24) -AA (1)-(molecular weight 10800
0) P-8; -St (60) -Bu (35) -DVB (3) -MAA (2)-latex (molecular weight 150,000) P-9; -St (70) -Bu (25) -DVB ( 2) -AA (3)-latex (molecular weight 280000) P-10; -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-latex (molecular weight 80000) P-11; -VDC (85) -MMA (5) -EA (5) -MAA (5)-latex (molecular weight 67,000) P-12; -Et (90) -MAA (10)-latex (molecular weight) 12000) P-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130
000) P-14; -MMA (63) -EA (35)-AA (2) latex (molecular weight 330
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; Divinylbenzene, VC; Vinyl chloride, AN; Acrylonitrile, VDC; Vinylidene chloride, Et; Ethylene, IA; Itaconic acid.

The polymer latexes described above are also commercially available, and the following polymers can be used. Examples of acrylic polymers include Sebian A-4635,4658
3,4601 (all manufactured by Daicel Chemical Industries, Ltd.), Nipol Lx811, 8
Examples of poly (esters) such as 14, 821, 820, 857 (all manufactured by Nippon Zeon Co., Ltd.) include FINETEX ES650, 611, 67
5, 850 (all manufactured by Dainippon Ink and Chemicals, Inc.), WD-size, WMS
(Manufactured by Eastman Chemical), poly (urethane)
Examples of such rubbers include HYDRAN AP10, 20, 30, 40 (all manufactured by Dainippon Ink and Chemicals, Inc.). Examples of rubbers include LACSTAR
7310K, 3307B, 4700H, 7132C (Dai Nippon Ink Chemicals
Nipol Lx416, 410, 438C, 2507 (Nippon Zeon Co., Ltd.)
Examples of poly (vinyl chloride) s such as G35
Examples of poly (vinylidene chloride) s such as 1, G576 (all manufactured by Zeon Corporation) include L502 and L513 (all manufactured by Asahi Kasei Corporation)
Examples of poly (olefins) include Chemipearl S120 and SA100 (all manufactured by Mitsui Petrochemical Co., Ltd.). These polymer latexes may be used alone, or may be blended as required.

The polymer latex used in the present invention is particularly preferably a styrene-butadiene copolymer latex. The weight ratio of the styrene monomer unit to the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 40:60 to 95: 5. Also,
The proportion of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 60 to 99% by mass. The preferred molecular weight range is the same as described above. Examples of the styrene-butadiene copolymer latex that is preferably used in the present invention include the above-mentioned P-3 to P-8, and commercially available products such as LACSTAR-3307B, 7132C, and Nipol Lx416.

As the latex, the glass transition temperature (T
g) is preferably in the range of 10C to 80C, more preferably in the range of 20C to 60C. When two or more latexes having different Tg are blended and used, the weight average Tg is preferably within the above range.

The image forming layer of the photothermographic material may optionally contain a hydrophilic polymer such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose and carboxymethylcellulose.
The amount of the hydrophilic polymer to be added is preferably 30% by mass or less, more preferably 20% by mass or less of the total binder in the image forming layer.

Organic silver salt-containing layer (that is, image forming layer)
Is preferably formed using a polymer latex. The amount of binder in the image forming layer depends on the total amount of binder.
The weight ratio of the organic / silver salt is preferably from 1/1 to 10/1, more preferably from 1/5 to 4/1. Further, such an image forming layer is usually a photosensitive layer (emulsion layer) containing a photosensitive silver halide which is a photosensitive silver salt, and in such a case, the total binder / silver halide is used. The weight ratio is preferably in the range of 400-5, more preferably in the range of 200-10. The total amount of the binder in the image forming layer is preferably from 0.2 to 30 g / m ² , more preferably from 1 to 15 g / m ² . A crosslinking agent for crosslinking and a surfactant for improving coating properties may be added to the image forming layer.

Solvent of coating solution for image forming layer of photothermographic material
(Here, for the sake of simplicity, the solvent and the dispersion medium are collectively referred to as “solvent”), and is preferably an aqueous solvent containing 30% by mass or more of water. As a component other than water, any water-miscible organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, and ethyl acetate may be used. The water content of the solvent in the coating solution is preferably 50% by mass or more, more preferably 70% by mass or more. Examples of preferred solvent composition include water, water / methyl alcohol = 90/10, water / methyl alcohol = 70/30, water / methyl alcohol / dimethylformamide = 80/15/5, water / methyl alcohol / Ethyl cellosolve = 85/10/5, water / methyl alcohol / isopropyl alcohol = 85/10/5, etc. (numerical values are mass%).

Examples of the antifoggant, stabilizer and stabilizer precursor are described in JP-A-10-62899, paragraph 0070;
EP-A-0 080 364 A1, page 20, line 57 to 21
What is described on page 7 line is mentioned. The antifoggants preferably used in the present invention are organic halides, and examples thereof include those described in paragraphs 0111 to 0112 of JP-A-11-65021. Especially Japanese Patent Application 11
-87297, an organic halogen compound represented by the formula (P),
Organic polyhalogen compounds represented by the general formula (II) in JP-A-10-339934 are preferred.

The preferred polyhalogen compound 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, and Y is a divalent linkage. Represents a 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 σp. Specifically, a cyano group, an alkoxycarbonyl group,
Examples include an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfoxide group, an acyl group, a heterocyclic group, a halogen atom, a halogenated alkyl group, and a phosphoryl group. The σp value is preferably in the range of 0.2 to 2.0, and more preferably in the range of 0.4 to 1.0.
Particularly preferred as the electron-withdrawing group are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group,
Of the alkylphosphoryl groups, a carbamoyl group is most preferred. Specific examples of the compound of the general formula (III) are shown below.

[0124]

Embedded image

[0125]

Embedded image

[0126]

Embedded image

The compound represented by the formula (III) is preferably used in an amount of 10 ^-4 to 1 mol, more preferably 10 ^-3 , per mol of the non-photosensitive silver salt in the image forming layer.
０．８0.8 mol, more preferably 5 × 10
It is preferably used in the range of ^{-3 to} 0.5 mol. Examples of the method for incorporating the antifoggant into the photosensitive material include the methods described as the method for containing the reducing agent, and it is preferable that the organic polyhalogen compound is also added as a solid fine particle dispersion.

Other antifoggants include those described in JP-A-11-11
-65021 Publication Paragraph No. 0113 mercury (II) salt, the same publication paragraph No. 0114 benzoic acid, formula (Z) of Japanese Patent Application No. 11-87297.
, A formalin scavenger compound represented by the formula (S) of Japanese Patent Application No. 11-23995, a triazine compound according to claim 9 of Japanese Patent Application Laid-Open No. 11-352624, Examples include the compound represented by the general formula (III) in the publication, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene and the like.

The photothermographic material 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-59-193447, a compound described in JP-B-55-12581, and a compound represented by the general formula (JP-A-60-153039). The compound represented by II) is mentioned. The azolium salt may be added to any part of the light-sensitive material, but it is preferable to add the azolium salt to the layer having the photosensitive layer, more preferably to the image forming layer. The azolium salt may be added at any time during the preparation of the coating solution. When it is added to the image forming layer, any step from the preparation of the organic silver salt to the preparation of the coating solution may be used, but it is preferable that it is after the preparation of the organic silver salt and immediately before the coating. Powder, azolium salt addition method,
Any method such as a solution or a fine particle dispersion may be used.
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 addition amount of the azolium salt may be any amount, but is preferably 1 × 10 ⁻⁶ mol to 2 mol, more preferably 1 × 10 ⁻³ mol to 0.5 mol per mol of silver.

A mercapto compound is used for the purpose of suppressing or promoting development to control development, improving spectral sensitization efficiency, and improving storage stability before and after development.
A disulfide compound and a thione compound can be contained. For example, paragraph number 0067 of JP-A-10-62899
To 0069, the compound represented by the general formula (I) in JP-A-10-186572, and the compounds described in paragraphs 0033 to 0052 as specific examples thereof, European Patent Publication No. 00803764A
Compounds described on page 20, lines 36 to 56 of JP-A No. 1 and compounds described in Japanese Patent Application No. 11-273670 can be exemplified. Among them, mercapto-substituted heteroaromatic compounds are preferred.

It is preferable to add a toning agent to the photothermographic material. Regarding the toning agent, paragraphs 0054 to 0055 of JP-A-10-62899, page 23 to line 48 of EP-A-0 080 364 A1, described in Japanese Patent Application No. 10-213487, 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); combinations of phthalazinones with phthalic acids (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride) Phthalazines (phthalazine, phthalazine derivatives or metal salts;
For example, 4- (1-naphthyl) phthalazine, 6-isopropylphthalazine, 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 particularly preferred.

The plasticizers and lubricants that can be used in the photosensitive layer are described in paragraph No. 01 of JP-A-11-65021.
17, ultra-high contrast agent for forming a super-high contrast image and the addition method and amount thereof, paragraph number 0118 of the same publication, JP-A-11-223
No. 898, paragraph Nos. 0136 to 0193, Formula (H) of Japanese Patent Application No. 11-87297, Formulas (1) to (3), compounds of the formulas (A) and (B), Japanese Patent Application No. The compounds of the general formulas (III) to (V) described in the specification of Japanese Patent No. 91652 (specific compounds: Chemical formulas 21 to 24), and the contrast enhancement accelerator are described in JP-A-11-65021, paragraph No. 0102,
No. 11-223898, paragraphs 0194-0195.

To use formic acid or formate as a strong fogging substance, the side having the image-forming layer containing the photosensitive silver halide has a concentration of not more than 5 mmol, more preferably not more than 5 mmol per mol of silver.
It is preferable to contain it in an amount of not more than mmol.

When a super-high contrast agent is used in the photothermographic material, it is preferable to use an acid or a salt thereof formed by hydration of diphosphorus pentoxide 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), hexametaline Acid (salt)
And the like. Particularly preferred acids or salts thereof formed by hydration of diphosphorus pentoxide include:
Orthophosphoric acid (salt) and hexametaphosphoric acid (salt) can be mentioned. Specific salts include sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, and ammonium hexametaphosphate. Use amount of the oxidizing acid or salt thereof formed by hydration of diphosphorus (coating amount per photographic material 1 m ²⁾ may be a desired amount depending on the performance such as sensitivity and fog, but 0.1 to 500
Preferably ^{mg / m 2, 0.5~100mg / m} 2 is more preferable.

The photothermographic material can 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, paragraph No. 0119 of JP-A-11-65021
To 0120. Gelatin is preferred as the binder for the surface protective layer used in the present invention, but polyvinyl alcohol (PVA) is also preferred. As the gelatin, inert gelatin (for example, Nitta Gelatin 75)
0), phthalated gelatin (for example, Nitta Gelatin 801) and the like can be used. As the PVA, completely saponified PVA-105, partially saponified PVA-205, P
VA-335, modified polyvinyl alcohol MP-20
3 (these are trade names manufactured by Kuraray Co., Ltd.). Preferably 0.3 to 4.0 g / m ² of polyvinyl alcohol coating amount as (per support 1 m ²⁾ is the protective layer (per one layer), 0.3 to 2.0 g / m ² is more preferable.

In particular, when a photothermographic material 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 Taira Okuda and Hiroshi Inagaki, published by Kobunshi Kankokai (197
8))), "Applications of Synthetic Latex (Edited by Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara, Polymer Publishing Association (19)
93)) "," Synthesis of Synthetic Latex (Souichi Muroi, published by Kobunshi Kankokai (1970)) "and the like. Specifically, methyl methacrylate (33.5% by mass) / ethyl acrylate (50% by mass) / methacrylic acid (16.5% by mass)
Latex of copolymer, methyl methacrylate (47.5
Mass%) / butadiene (47.5 mass%) / itaconic acid (5 mass%)
Latex of copolymer, latex of copolymer of ethyl acrylate / methacrylic acid, methyl methacrylate (58.9% by 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-hydroxyethyl methacrylate (5.0% by mass) /
Latex of acrylic acid (2.0% by mass) copolymer, and the like. Furthermore, as a binder for the surface protective layer,
Combinations of polymer latex of Japanese Patent Application No. 11-6872, techniques described in paragraphs 0021 to 0025 of Japanese Patent Application No. 11-143058, paragraphs 0027 to 0028 of Japanese Patent Application No. 11-6872.
The technology described in paragraph No. 0023 of Japanese Patent Application No. 10-199626.
To 0041 may be applied. The ratio of the polymer latex of the surface protective layer is from 10% by mass to 90% of the total binder.
% By mass, and particularly preferably from 20% by mass to 80% by mass. The amount of the binder (including the water-soluble polymer and the latex polymer) applied to the surface protective layer (per layer) is preferably 0.3 to 5.0 g / m ² (per 1 m ^{2 of the} support).
~2.0g / m ² is more preferable.

The preparation temperature of the coating solution for the image forming layer is from 30 ° C. to 65 ° C.
The temperature is more preferably 35 ° C. or more and less than 60 ° C., and more preferably the temperature is 35 ° C. to 55 ° C. In addition, the temperature of the image forming layer coating solution immediately after the addition of the polymer latex was 30
It is preferred that the temperature be maintained between 0C and 65C. Preferably, the reducing agent and the organic silver salt are mixed before the addition of the polymer latex.

The image forming layer can be composed of one or more layers on a support. When it is composed of one layer, it is composed of an organic silver salt, a light-sensitive silver halide, a reducing agent, and a binder, and is prepared so as to contain optional additional materials such as a toning agent, a coating auxiliary and other auxiliary agents as necessary. You. 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, and the second image-forming layer or both layers contain some. Can be prepared to include other components. The construction of the multicolor photothermographic material may include a combination of these two layers for each color, see U.S. Pat.
All components may be contained in a single layer as described in US Pat. In the case of a multi-dye, multi-color photosensitive heat-developable photographic material, each emulsion layer is generally comprised of US Pat. No. 4,460,681.
As described in the specification, the use of a functional or non-functional barrier layer between each photosensitive layer keeps it distinct from each other.

Various dyes and pigments (for example, CI Pigment Blue 60, CI Pigment, etc.) are used in the photosensitive layer from the viewpoint of improving color tone, preventing interference fringes during laser exposure, and preventing irradiation.
Blue 64, CI Pigment Blue 15: 6) can be used. These are described in detail in International Publication WO98 / 36322, JP-A-10-268465, JP-A-11-338098 and the like. In the photothermographic material, an antihalation layer can be provided on the side farther from the light source than the photosensitive layer.

The photothermographic material generally has a non-photosensitive layer in addition to the 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 disclosed in
-65021, paragraph numbers 0123 to 0124, JP-A-11-223898
No. 9-230531, No. 10-36695, No. 10-1
These are described in JP-A-04779, JP-A-11-231457, JP-A-11-352625 and JP-A-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. Is preferred. In particular, it is preferable to add a thermal decoloring dye and a base precursor to the non-photosensitive layer to function as an antihalation layer. These technologies are described in
It is described in JP-A-11-231457.

The amount of the decolorizable dye to be added can be determined according to the use of the dye. Generally, it can be used in an amount having an optical density (absorbance) of more than 0.1 when measured at a target wavelength. The optical density is preferably from 0.2 to 2. The amount of the dye used to obtain such an optical density is generally about 0.001 to 1 g / m ² . When the dye was decolored in this manner, the optical density after thermal development was 0.1%.
It can be reduced to: 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 the thermal decoloring using such a decolorizing dye and a base precursor, when mixed with a base precursor as described in JP-A-11-352626, the melting point is 3 ° C.
It is preferable to use a substance (for example, diphenylsulfone, 4-chlorophenyl (phenyl) sulfone) that reduces the temperature by at least (deg) in terms of thermal decoloration and the like.

A colorant having an absorption maximum at 300 to 450 nm can be added to the photothermographic material for the purpose of improving the silver tone and the aging of the image. Such colorants are disclosed in JP-A-62-210458, JP-A-63-104046, and JP-A-63-10323.
No. 5, No. 63-208846, No. 63-306436, No. 6
3-314535 JP, JP-A-01-61745 JP, Japanese Patent Application No. 11-276
No. 751 and the like. 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 may be a so-called single-sided photosensitive material having at least one photosensitive layer containing a silver halide emulsion on one side of a support and a back layer on the other side. preferable.

It is preferable to add a matting agent to the photothermographic material to improve transportability. Matting agents are described in JP-A-11-65021, paragraphs 0126 to 0127. The matting agent is preferably 1 to 400 mg / m ² , more preferably 5 to 400 mg / m ² , when the coating amount is shown per 1 m ² of the light-sensitive material.
300300 mg / m ² . Further, the matte degree of the emulsion surface is not particularly limited as long as stardust failure does not occur, but the Bekk smoothness is 30%.
Seconds to 2000 seconds are preferred, and particularly 40 seconds to 1500 seconds are preferred.
The Beck smoothness is measured by Japanese Industrial Standards (JIS) P8119 “Smoothness test method of paper and paperboard with Beck tester” and
It can be easily obtained by TAPPI standard method T479.

The matting degree of the back layer is preferably such that the Beck smoothness is from 10 to 1200 seconds, preferably from 20 to 800 seconds.
More preferably, it is 40 seconds to 500 seconds. The matting agent is preferably contained in the outermost surface layer of the photosensitive material, a layer functioning as the outermost surface layer, or a layer near the outer surface, and is preferably contained in a layer acting as a so-called protective layer. The back layer is described in paragraphs 0128 to 0130 of JP-A-11-65021.

The photothermographic material has a film surface p before heat development.
H is preferably 6.0 or less, and more preferably 5.5 or less. There is no particular lower limit,
It is about 3. For adjusting the film surface pH, it is preferable to use an organic acid such as a phthalic acid derivative, a nonvolatile acid such as sulfuric acid, or a volatile base such as ammonia from the viewpoint of reducing the film surface pH. In particular, ammonia is easy to evaporate,
It is preferable for achieving a low film surface pH because it can be removed before the coating step or thermal development. The method of measuring the film surface pH is described in paragraph No. 0123 of Japanese Patent Application No. 11-87297.

A hardener may be used for each layer such as the photosensitive layer, the protective layer, and the back layer used in the present invention. Examples of hardeners include “THE THEORY OF THE PHOTOGRAPHIC P” by TH James.
ROCESS FOURTH EDITION ”(Macmillan Publishing Co.,
Inc., 1977), each method described on pages 77 to 87, chrome alum, 2,4-dichloro-6-hydroxy-s-
Triazine sodium salt, N, N-ethylenebis (vinylsulfoneacetamide), N, N-propylenebis (vinylsulfoneacetamide), polyvalent metal ions described on page 78 of the same book, US Pat. No. 4,281,060, Kaihei 6
-208193, epoxy compounds such as U.S. Pat.
Vinylsulfone compounds such as those disclosed in JP-A-2-89048 are preferably used.

The hardener is added as a solution. The time of adding this solution to the coating solution for the protective layer is from 180 minutes to immediately before coating, preferably from 60 minutes to 10 seconds before coating. The mixing conditions are not particularly limited as long as the effects of the present invention are sufficiently exhibited. As a specific mixing method, 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, by N. Harnby, MF Edwards, AW Nienow, Takahashi There is a method using a static mixer or the like described in Chapter 8 of Koji Translated "Liquid Mixing Technology" (Nikkan Kogyo Shimbun, 1989).

For the surfactant applicable to the present invention, paragraph No. 0132 of JP-A-11-65021, for the solvent, paragraph 0133 of the same publication, for the support, paragraph 0134 of the same publication for the support, antistatic Or paragraph No. 0135 of the same publication for the conductive layer, paragraph No. 0136 of the same publication for the method of obtaining a color image, and JP-A-11-84573 for the slipping agent
Paragraph Nos. 0061 to 0064 of Japanese Patent Application Laid-Open Publication No. Hei 11-106881, and Paragraph Nos. 0049 to 0062 of Japanese Patent Application No. 11-106881.

The transparent support is a polyester which has been subjected to a heat treatment at a temperature in the range of 130 to 185 ° C. in order to alleviate the internal strain remaining in the film at the time of biaxial stretching and to eliminate the heat shrinkage distortion generated during the heat development processing. 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,
It may be colored with dye-1) described in Examples of JP-A-240877, or may be uncolored. For the support, JP-A-11-84574
It is preferable to apply an undercoating technique such as a water-soluble polyester of JP-A No. 10-186565, a styrene-butadiene copolymer of JP-A-10-186565, and a vinylidene chloride copolymer of Paragraph Nos. 0063 to 0080 of Japanese Patent Application No. 11-106881. . Further, regarding the antistatic layer or the undercoat, JP-A-56-143430,
Nos. 6-143431, 58-62646, 56-120519, paragraphs 0040 to 0051 of JP-A-11-84573, U.S. Pat.No. 5,575,957, JP-A-11-223898. The technology described in paragraph numbers 0078 to 0084 can be applied.

The photothermographic material 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). The photothermographic material may further contain an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber or a coating aid.
Various additives can be added to either the photosensitive layer or the non-photosensitive layer. International publication about them
WO98 / 36322, European Patent Publication EP803764A1, JP-A-10-186567, JP-A-10-18568 and the like can be referred to.

The photothermographic material may be applied by any method. Specifically, various coating operations are used, including extrusion coating, slide coating, curtain coating, dip coating, knife coating, flow coating, or extrusion coating using a hopper of the type described in U.S. Pat.No. 2,681,294, Stephen F. Kistler, Petert M.
Extrusion coating or slide coating described in "LIQUIDFILM COATING" by Schweizer (published by CHAPMAN & HALL, 1997), pages 399 to 536, is preferably used. Particularly preferably, slide coating is used. An example of the shape of a slide coater used for slide coating is described in FIG. If desired, two or more layers can be simultaneously coated by the method described on pages 399 to 536 of the same book, US Pat. No. 2,761,791 and British Patent No. 837,095.

The coating solution for the image forming layer is preferably a so-called thixotropic fluid. The thixotropic property refers to a property in which the viscosity decreases as the shear rate increases. Although any device may be used for the viscosity measurement, an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. is preferably used, and the viscosity is measured at 25 ° C. The viscosity of the coating solution for the image forming layer at a shear rate of 0.1 S ^-1 is preferably from 400 mPa · s to 100,000 mPa · s, and more preferably from 500 mPa · s to 20,000 mPa · s. Further, at a shear rate of 1000 S ^-1 , 1 mPas to 200 mP
as is preferable, and more preferably 5 mPas to 80 mPas
It is.

Various systems expressing thixotropy are known, and are described in “Lecture / Rheology” edited by Polymer Publishing Association, Muroi,
It is described in Morino co-authored "Polymer Latex" (published by the Society of Polymer Publishing). In order for a fluid to exhibit thixotropic properties, it is necessary to contain a large amount of solid fine particles.
In order to enhance the thixotropic property, it is effective to include a thickened linear polymer, to increase the aspect ratio of the contained solid fine particles in an anisotropic shape, to use an alkali thickener, and to use a surfactant.

Examples of techniques that can be used in the production of photothermographic materials include EP 803764A1, EP 883022A1, WO 98/36322, JP 56-62648, 58-62644, JP-A-Hei.
No. 9-281637, No. 9-297367, No. 9-304869, No. 9-311405, No. 9-329865, No. 10-10669
No. 10-62899, No. 10-69023, No. 10-1
No. 86568, No. 10-90823, No. 10-171063,
No. 10-186565, No. 10-186567, No. 10-186569
No. 10-186572, No. 10-197974, No. 10-197
No. 982, No. 10-197983, No. 10-197985 to No. 10-
No. 197987, No. 10-207001, No. 10-207004, No. 10-221807, No. 10-282601, No. 10-288
No. 823, No. 10-288824, No. 10-307365,
JP 10-312038, JP 10-339934, JP 11-7100, JP 11-15105, JP 11-24200, JP 11-242
No. 01, No. 11-30832, No. 11-84574, No. 11
No. -65021, No. 11-109547, No. 11-125880, No. 11-129629, No. 11-133536 to No. 11-133539
No. 11-133542, No. 11-133543, No. 11
-223898 and 11-352627.

The photothermographic material may be developed by any method, but is usually developed by raising the temperature of the photothermographic material exposed imagewise. Preferred development temperature is
The temperature is 80 to 250 ° C, more preferably 100 to 140 ° C. The development time is preferably from 1 to 180 seconds, more preferably from 10 to 90 seconds, and particularly preferably from 10 to 40 seconds.

As a method of thermal development, a plate heater method is preferable. As a heat development method using a plate heater, a method described in JP-A-11-133572 is preferable. A preferred heat development device is a heat development device that obtains a visible image by contacting a photothermographic material having a latent image formed thereon with a heating unit in a heat development unit, wherein the heating unit includes a plate heater, and A plurality of pressing rollers are provided to face each other along one surface of the plate heater, and heat development is performed by passing the photothermographic material between the pressing roller and the plate heater. This is a heat developing device. It is preferable to divide the plate heater into two to six stages and lower the temperature at the tip part by about 1 to 10 ° 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 material can also be suppressed.

The photothermographic material may be exposed by any method, but a laser beam is preferred as an exposure light source. As the laser light, a gas laser (Ar ⁺ , He-Ne), a YAG laser, a dye laser, a semiconductor laser, or the like is preferable. 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, see Fuji Medical Review No. 8,
The techniques are described on pages 39 to 55, and these techniques can be applied as a laser imager for photothermographic materials. "AD network" proposed by Fuji Medical System as a network system conforming to the DICOM standard
It can also be applied as a photothermographic material for a laser imager in the above.

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

[0162]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. Example 1 (Preparation of PET support) Terephthalic acid and ethylene glycol
Of intrinsic viscosity IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (weight ratio) at 25 ° C.) according to a conventional method.
I got After pelletizing this, dried at 130 ° C for 4 hours,
After being melted at 300 ° C., it was extruded from a T-die and rapidly cooled to prepare an unstretched film having a thickness of 175 μm after heat setting.

This was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then horizontally stretched 4.5 times using a tenter. 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 lateral direction at the same temperature. Then, after slitting the chuck portion of the tenter, knurling was performed on both ends and wound at 4 kg / cm ² 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, it was found that the support was treated at 0.375 kV · A · min / m ² . At this time, the processing frequency was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

(Preparation of Undercoating Support) (1) Preparation of Coating Solution for Undercoating Layer Prescription (for undercoating layer on photosensitive layer side) Pesresin A-515GB (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd. 234 g Polyethylene glycol monononyl Phenyl ether (average ethylene oxide number = 8.5) 10% by mass solution 21.5g Soken Chemical Co., Ltd. MP-1000 (polymer fine particles, average particle size 0.4μm) 0.91g distilled water 744ml

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

Formulation (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) 89.2 g Shin-Etsu Chemical Co., Ltd. ) Metrolose TC-5 (2 mass% aqueous solution) 8.6 g Soken Chemical Co., Ltd. MP-1000 0.01 g 1 mass% aqueous solution of sodium dodecylbenzenesulfonate 10 ml NaOH (1 mass%) 6 ml Proxel (manufactured by ICI) 1 ml 805 ml of distilled water

(Preparation of Undercoating Support) Thickness 175 μm
After performing the above-mentioned corona discharge treatment on both sides of the biaxially stretched polyethylene terephthalate support, the above-mentioned undercoating coating solution formulation was applied on one side (photosensitive layer side) 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 coating amount was 5.7 ml / m ² . At 5 ° C. for 5 minutes, and further apply the above-mentioned undercoating solution formulation to the back surface (back surface) with a wire bar so that the wet coating amount is 7.7 ml / m ^2, and then dry at 180 ° C. for 6 minutes to obtain an undercoating support. It was created.

(Preparation of Back Surface Coating Solution) (Preparation of Solid Precursor Dispersion (a) of Base Precursor) 64 g of base precursor compound 11, 28 g of diphenyl sulfone, and 10 g of Demol N surfactant manufactured by Kao Corporation are distilled. Mix with 220 ml of water and mix the mixture with a sand mill (1/4 Gallon
The beads were dispersed using a sand grinder mill (manufactured by 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 mixed with 305 ml of distilled water, and the mixture was subjected to a sand mill (1/4 Gallon sand grinder mill, Using IMEX Co., Ltd.) and dispersing the beads, average particle diameter
A 0.2 μm dispersion of solid dye fine particles was obtained.

(Preparation of antihalation layer coating solution) Gelatin 17g, polyacrylamide 9.6g, solid fine particle dispersion (a) of the above-mentioned base precursor (a) 70g, dye solid fine particle dispersion 56g, monodispersed polymethyl methacrylate fine particles (average particle Size 8 μm, Particle size standard deviation 0.4) 1.5 g, Benzoisothiazolinone 0.03 g, Polyethylene sodium sulfonate 2.2 g, Blue dye compound 14 0.2 g, Yellow dye compound 15
Was mixed with 3.9 g of water and 844 ml of water to prepare an antihalation layer coating solution.

(Preparation of back surface protective layer coating solution)
℃, gelatin 50g, polystyrene sodium sulfonate 0.2g, N, N-ethylenebis (vinylsulfoneacetamide) 2.4g, t-octylphenoxyethoxyethaneethanesulfonate 1g, benzoisothiazolinone 30mg, N-perfluoro Octylsulfonyl-N-propylalanine potassium salt 37 mg, polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-
2-aminoethyl) ether [ethylene oxide average polymerization degree 15] 0.15 g, C ₈ F ₁₇ SO ₃ K32 mg, C ₈ F ₁₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ CH
₂ O) ₄ (CH ₂ ) ₄ -SO ₃ Na 64 mg, acrylic acid / ethyl acrylate copolymer (copolymerization weight ratio 5/95) 8.8 g, Aerosol OT (manufactured by American Cyanamid Co.) 0.6 g, flowing The paraffin emulsion was mixed with 1.8 g of liquid paraffin and 950 ml of water to prepare a back surface protective layer coating solution.

<< Preparation of Silver Halide Emulsion 1 >> Distilled water 1421
Add 3.1 ml of a 1% by weight potassium bromide solution to the
While stirring the liquid containing 3.5 ml of ol / L sulfuric acid and 31.7 g of phthalated gelatin in a stainless steel reaction pot, maintain the liquid temperature at 34 ° C, add distilled water to 22.22 g of silver nitrate and dilute to 95.4 ml. Solution A and 15.9 g of potassium bromide in distilled water with a capacity of 97.4 m
Solution B diluted to 1 was added at a constant flow rate over 45 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and a 10% by mass aqueous solution of benzimidazole was further added to 1 ml of the aqueous solution.
0.8 ml was added. Further, a solution C obtained by adding distilled water to 51.86 g of silver nitrate to 317.5 ml and a solution D obtained by diluting 45.8 g of potassium bromide to a volume of 400 ml with distilled water were added at a constant flow rate over 20 minutes. Solution D was added by a controlled double jet method while maintaining pAg at 8.1.
Iridium hexachloride so as to be 1 × 10 ^-4 mol per mol of silver
(III) 10 minutes after the start of adding the solution C and the solution D, the entire amount of the potassium salt of the acid was added. 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. The pH was adjusted to 3.8 using sulfuric acid having a concentration of 0.5 mol / L, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.

While stirring the above silver halide dispersion, 38
C. and 0.34% by weight of 1,2-benzisothiazoline
5 ml of a methanol solution of -3-one was added, and 40 minutes later, a methanol solution of spectral sensitizing dye A was added at 1 × 10 ^-3 mol per mol of silver, and the temperature was raised to 47 ° C. one minute later. Sodium benzenethiosulfonate after 20 minutes of heating the silver 7.6 × 10 ^-5 mol per 1 mol in a methanol solution was added at 1 mol of silver per 1.9 × 10 further tellurium sensitizer B in methanol solution after 5 minutes ^{- 4} mol was added and the mixture was aged for 91 minutes. 1.3 ml of a 0.8% by mass methanol solution of N, N'-dihydroxy-N "-diethylmelamine was added,
After a further 4 minutes, 5-methyl-2-mercaptobenzimidazole was dissolved in a methanol solution to give 3.7 × 10 ^-3 mol per mol of silver and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole. 4.9 × 10 ^-3 per mole of silver in methanol solution
A silver halide emulsion 1 was prepared by molar addition.

The grains in the prepared silver halide emulsion are as follows:
Pure silver bromide particles having an average equivalent spherical diameter of 0.046 μm and a coefficient of variation of equivalent spherical diameter of 20% were obtained. Use an electron microscope to determine particle size, etc.
It was determined from the average of 1000 particles. The [100] plane ratio of these particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of Silver Halide Emulsion 2 >> Halogenation
In preparing silver emulsion 1, the liquid temperature at the time of grain formation was changed from 34 ° C to 49 ° C.
To 30 minutes, and the addition time of solution C was changed to 30 minutes.
(II) Halogenation is performed in the same manner except that potassium is removed.
Preparation of silver emulsion 2 was performed. Same as silver halide emulsion 1
Precipitation / desalting / washing / dispersion was performed. Further spectral sensitizing dyes
A was added in an amount of 7.5 × 10^-FourMole, tellurium sensitization
Agent B was added in an amount of 1.1 × 10^-FourMol, 1-phenyl
Ru-2-heptyl-5-mercapto-1,3,4-triazole to silver
3.3 × 10 per mole ^-3Emulsion 1
Similarly, spectral sensitization, chemical sensitization and 5-methyl-2-merca
Putbenzimidazole, 1-phenyl-2-heptyl-5-me
Add lcapto-1,3,4-triazole and add halogen
Silver halide emulsion 2 was obtained. The emulsion grains of the silver halide emulsion 2 were:
Pure odor with average sphere equivalent diameter of 0.080 μm and sphere equivalent diameter variation coefficient of 20%
It was silver halide cubic grains.

<< Preparation of Silver Halide Emulsion 3 >> In the preparation of silver halide emulsion 1, the liquid temperature of 34 ° C. during grain formation was changed to 27 ° C.
Silver halide emulsion 3 was prepared in the same manner except that the above was changed. Further, as in the case of the silver halide emulsion 1, the precipitation /
Desalting / water washing / dispersion was performed. The spectral sensitizing dye A was added as a solid dispersion (aqueous gelatin solution) in an amount of 6 × 10 ⁻³ mol per mol of silver, and the tellurium sensitizer B was added in an amount of 5.2 × 10 ⁻⁴ per mol of silver.
A silver halide emulsion 3 was obtained in the same manner as in the emulsion 1, except that the mole was changed. The emulsion grains of the silver halide emulsion 3 were pure silver bromide cubic grains having an average sphere equivalent diameter of 0.038 μm and a coefficient of variation of the sphere equivalent diameter of 20%.

<< Preparation of mixed emulsion A for coating solution >> Silver halide emulsion 1 was 70% by mass, silver halide emulsion 2 was 15% by mass,
15% by mass of silver halide emulsion 3 was dissolved, and benzothiazolium iodide was dissolved in a 1% by mass aqueous solution at a concentration of 7 × per mole of silver.
10 ^-3 mol was added.

<< Preparation of Comparative Organic Acid Silver Salt Dispersion A >> 87.6 kg of behenic acid (product name: Edenor C22-85R) manufactured by Henkel, 423 L of distilled water, 49.2 L of a 5 mol / L NaOH aqueous solution, 49.2 L of tert-butanol Were mixed and reacted at 75 ° C. for 1 hour with stirring to obtain a sodium behenate solution. Separately, 206.2 L (pH 4.0) of an aqueous solution of 40.4 kg of silver nitrate was prepared and kept at 10 ° C. 635
1 L of distilled water and 30 L of tert-butanol
While keeping the temperature at 30 ° C and stirring, the total amount of the sodium behenate solution and the total amount of the silver nitrate aqueous solution were each 93
Minutes were added over 15 seconds and 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 sodium behenate solution was started.
For 14 minutes and 15 seconds after completion of the addition of the aqueous silver nitrate solution, only the sodium behenate solution was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The piping of the addition system of the sodium behenate solution was kept warm by steam tracing, and the steam opening was adjusted so that the liquid temperature at the outlet of the tip of the addition nozzle became 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 sodium behenate 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.

After the completion of the addition of the sodium behenate solution, the mixture was left to stir at the same temperature for 20 minutes, and the temperature was lowered to 25 ° C. Thereafter, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of the filtered water became 45 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying. When the morphology of the obtained silver behenate particles was evaluated by electron micrographing, a = 0.
14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter 0.52 μm, and flake-like crystal with a sphere equivalent diameter variation coefficient of 15%. (A, b, c are the rules of the text)

To a wet cake having a dry solid content of 100 g, 74 g of a 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-217) and water were added to make a total amount of 385 g, and the mixture was predispersed with a homomixer. Next, the pre-dispersed stock solution is mixed with a dispersing machine (trade name: Microfluidizer M-
The pressure of 110S-EH, manufactured by Microfluidics International Corporation, using a G10Z interaction chamber) was adjusted to 1250 kg / cm ² , and the mixture was treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of Comparative Organic Silver Salt Dispersion B >> Five minutes after the completion of the addition of the sodium behenate solution, a 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-217) was reacted with silver behenate. Silver behenate was reacted in the same manner as in Comparative Organic Silver Salt Dispersion A, except that 74 g was added per 100 g of dry solids. The obtained mixture was transferred to an ultrafiltration device shown in FIG. 1 and subjected to a desalting treatment. The ultrafiltration device basically comprises a tank 1 for storing the organic silver salt dispersion and a circulation pump 2 for supplying the stored dispersion to the ultrafiltration module 3. It has a total 4, a flow meter 5 for measuring permeated water, a pump 6 for reverse washing. The membrane module used was a hollow type ACP-1050 manufactured by Asahi Kasei Corporation. The flow rate was set at 10 liters / minute, and the pressure before and after the module was set at 1.0 kg / cm ² . When the electric conductivity of the silver behenate solution dropped to 90 μS / cm, the replenishment of pure water was stopped, and the solution was concentrated until the silver behenate solid content became 26% by weight. For the measurement of the solid content concentration, a digital hydrometer DA-300 manufactured by Kyoto Electronics Co., Ltd. was used.

<< Preparation of Comparative Organic Silver Salt Dispersion C >> A silver behenate solution having a solid content of 26% by weight was prepared in the same manner as Comparative Organic Silver Salt Dispersion B, and then dispersed in a dispersing machine (trade name: Microfluid). Dither M-110S-EH, manufactured by Microfluidics International Corporation, G1
0Z interaction chamber) pressure of 125
The mixture was adjusted to 0 kg / cm ² and treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of Comparative Organic Acid Silver Salt Dispersion D >> Five minutes after the completion of the addition of the sodium behenate solution, 100 g of a dry solid content of silver behenate reacted with a 1% by weight aqueous solution of anionic surfactant S1 Silver behenate was reacted in the same manner as in Comparative Organic Silver Salt Dispersion A, except that 404 ml was added. After the reaction is completed, polyvinyl alcohol (trade name: PVA-2
74 g of the 10% by weight aqueous solution of 17) was added per 100 g of dried solid content of reacted silver behenate, and the mixture was thoroughly stirred. The obtained mixture was transferred to the same ultrafiltration apparatus as the comparative organic silver salt dispersion B, and subjected to a desalting treatment. At the time of diafiltration, an anionic surfactant S1 aqueous solution was used as replenishing pure water, and filtration was performed while adjusting the surfactant concentration in the mixture.

When the electrical conductivity of the silver behenate solution dropped to 90 μm / cm, the addition of the replenishing solution was stopped, and the solution was concentrated until the silver behenate solid content became 26% by mass. The total amount of permeate collected by ultrafiltration was collected, the spectral absorption of the permeate was measured, and the amount of anionic surfactant in the permeate was estimated from the calibration curve of the anionic surfactant solution prepared in advance. . Further, the amount of the added surfactant was determined from the amount of the aqueous solution of the anionic surfactant replenished at the time of preparation, and the remaining amount of the anionic surfactant in the 26% by weight silver behenate solution was calculated. Per anionic surfactant S1 was a residual amount of 5 mol%.

<< Preparation of Comparative Organic Silver Salt Dispersion E >> Anionic surfactant S1 for replenishment during diafiltration
The comparative organic silver salt dispersion D was prepared except that the concentration of the aqueous solution was changed so that the residual amount of the anionic surfactant after adjusting the solid content of the silver behenate solution to 26% by mass was 2 mol%. A comparative organic silver salt dispersion E was prepared in the same manner.

<< Preparation of Comparative Organic Silver Salt Dispersion F >> Anionic surfactant S1 for replenishment during diafiltration
Organic silver salt dispersion D for comparison, except that the concentration of the aqueous solution was changed so that the residual amount of the anionic surfactant after adjusting the solid content of the silver behenate solution to 26% by mass was 1 mol%. A comparative organic silver salt dispersion F was prepared in the same manner.

<< Preparation of Comparative Organic Silver Salt Dispersion G >> Anionic surfactant S1 for replenishment during diafiltration
After adjusting the concentration of the aqueous solution to a solid content of silver behenate solution of 26% by mass, the residual amount of the anionic surfactant was 0.5 mol%.
Except that the organic silver salt dispersion D for comparison was changed to
Comparative Organic Silver Salt Dispersion G was prepared in the same manner as described above.

<< Preparation of Comparative Organic Silver Salt Dispersion H >> A solid content of 26% by weight was prepared in the same manner as in Comparative Organic Silver Salt Dispersion D.
After preparing a silver behenate solution, a disperser (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, G
Pressure of 10Z interaction chamber)
The mixture was adjusted to 50 kg / cm ² and treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of Comparative Organic Silver Salt Dispersion I >> A solid content of 26% by weight was prepared in the same manner as Comparative Organic Silver Salt Dispersion E.
After preparing a silver behenate solution, a disperser (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, G
Pressure of 10Z interaction chamber)
The mixture was adjusted to 50 kg / cm ² and treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of Organic Silver Salt Dispersion J According to the Method of the Present Invention >> A silver behenate solution having a solid content of 26% by weight was prepared in the same manner as Comparative Organic Silver Salt Dispersion F, and then dispersed in a dispersing machine (trade name). : Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using G10Z interaction chamber)
The pressure was adjusted to 1250 kg / cm ² , and the mixture was treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of Organic Silver Salt Dispersion K According to the Method of the Present Invention >> A silver behenate solution having a solid content of 26% by weight was prepared in the same manner as the comparative organic silver salt dispersion G, and then dispersed in a dispersing machine (trade name). : Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using G10Z interaction chamber)
The pressure was adjusted to 1250 kg / cm ² , and the mixture was treated three times to obtain a silver behenate dispersion. The cooling operation was set at a dispersion temperature of 18 ° C. by installing coiled heat exchangers before and after the interaction chamber, respectively, and adjusting the temperature of the refrigerant.

<< Preparation of 25% by mass dispersion of reducing agent >> 10 kg of 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane and modified polyvinyl alcohol (Kuraray)
10% of a 20% by weight aqueous solution of Poval MP203 manufactured by
6 kg was added and mixed well to form a slurry. This slurry is sent by a diaphragm pump and has an average diameter of 0.5 mm.
Horizontal sand mill filled with zirconia beads (UVM-
2: 3 hours and 30 minutes by using IMEX Co., Ltd., and then 0.2 g of benzoisothiazolinone sodium salt and water were added to adjust the concentration of the reducing agent to 25% by mass. I got The reducing agent particles contained in the thus obtained reducing agent dispersion had a median diameter of 0.42 μm and a maximum particle diameter of 2.0 μm or less. The resulting reducing agent dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 25% by Mass Dispersion of Reducing Agent Complex >>
2-methylenebis- (4-ethyl-6-tert-butylphenol)
10 kg of a 1: 1 complex of phenol and triphenylphosphine oxide and denatured polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval MP
To 10 kg of the 20% by mass aqueous solution of 203), 16 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 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 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 2.0 μm or less. The resulting reducing agent complex dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 10% by Mass Dispersion of Mercapto Compound >> 5 kg of 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole and modified polyvinyl alcohol (Kuraray)
8.3k of water to 5kg of a 20% by mass aqueous solution of Poval MP203 manufactured by
g was added and mixed well to form a slurry. This slurry was sent by a diaphragm pump, and a horizontal sand mill filled with zirconia beads having an average diameter of 0.5 mm (UVM-2:
After dispersing for 6 hours using IMEX Co., Ltd., water was added to adjust the concentration of the mercapto compound to 10% by mass to obtain a mercapto dispersion. The mercapto compound particles contained in the mercapto compound dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 2.0 μm or less. The obtained mercapto compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust, and stored. Immediately before use, the mixture was again filtered through a polypropylene filter having a pore size of 10 μm.

<< Preparation of 20% by mass dispersion of organic polyhalogen compound-1 >> 5 kg of tribromomethylnaphthyl sulfone
And modified polyvinyl alcohol (Poval MP manufactured by Kuraray Co., Ltd.)
203) 2.5 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate and 213 g of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate;
10 kg of water was added and mixed well to form a slurry. This slurry is sent by a diaphragm pump and has an average diameter of 0.5 m.
m zirconia beads filled horizontal sand mill (UVM-
2: manufactured by Imex Co., Ltd.) for 5 hours, and then added with 0.2 g of benzoisothiazolinone sodium salt and water to adjust the concentration of the organic polyhalogen compound to 20% by mass. A dispersion was obtained. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained have a median diameter of 0.36 μm and a maximum particle diameter of 2.0 μm.
m or less. The obtained organic polyhalogen compound dispersion was filtered with a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored.

<Preparation of 25% by mass dispersion of organic polyhalogen compound-2> Similar to 20% by mass dispersion of organic polyhalogen compound-1, except that 5 kg of tribromomethylnaphthyl sulfone was used instead of tribromomethyl ( Using 5 kg of 4- (2,4,6-trimethylphenylsulfonyl) phenyl) sulfone, the organic polyhalogen compound is dispersed in an amount of 25% by mass.
And filtered. The organic polyhalogen compound particles contained in the organic polyhalogen compound dispersion thus obtained had a median diameter of 0.38 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered with a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 26% by mass dispersion of organic polyhalogen compound-3 >> Similar to 20% by mass dispersion of organic polyhalogen compound-1, except that 5 kg of tribromomethylnaphthyl sulfone was used instead of tribromomethylphenyl Using 5 kg of sulfone, 5 wt% of a 20 wt% aqueous solution of MP203 was dispersed and diluted, and the organic polyhalogen compound was diluted to 26 wt% and filtered. The organic polyhalogen compound particles contained in the organic 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 3.0.
Filtration was performed with a μm polypropylene filter to remove foreign substances such as dust, and stored. After storage, it was stored at 10 ° C or less until use.

<< Preparation of 25% by mass dispersion of organic polyhalogen compound-4 >> Similar to 20% by mass dispersion of organic polyhalogen compound-1, except that 5 kg of tribromomethylnaphthyl sulfone was used instead of N-butyl- Disperse using 5 kg of 3-tribromomethanesulfonylbenzamide, dilute the organic polyhalogen compound to 25% by mass,
Filtration was performed. The organic polyhalogen compound particles contained in the organic polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered with a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust, and stored.

<< Preparation of 5% by mass solution of phthalazine compound >> 8 kg of modified polyvinyl alcohol MP2 manufactured by Kuraray Co., Ltd.
03 was dissolved in 174.57 kg of water, and then 3.15 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate.
14.28 kg of a 70% by mass aqueous solution of 6-isopropylphthalazine was added to prepare a 5% by mass solution of 6-isopropylphthalazine.

<< Preparation of 20% by Mass Dispersion of Pigment >>
ent Blue 60 64g and Kao Corporation's Demol N 6.4g water 250
g was added and mixed well to obtain a slurry. Average diameter 0.5mm
Of zirconia beads was placed in a vessel together with the slurry, and dispersed by a dispersing machine (1 / 4G sand grinder mill: manufactured by Imex Co., Ltd.) for 25 hours to obtain a pigment dispersion. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

<< Preparation of 40% by mass of SBR latex >> SBR latex purified by ultrafiltration (UF) was obtained as follows. The following SBR latex was diluted 10 times with distilled water and UF-
Using a purification module FS03-FC-FUY03A1 (Daisen Membrane System Co., Ltd.), dilute and purify until the ionic conductivity becomes 1.5 mS / cm, and Sanyo Chemical Co., Ltd. Sandet-BL
Was added to be 0.22% by mass. Further with NaOH and NH ₄ OH Na ⁺ ion: NH ₄ ⁺ ion = 1: was added to a 2.3 (molar ratio) was adjusted to pH 8.4. The latex concentration at this time was 40% by mass. (SBR latex: -St (68) -Bu (29) -AA (3)-latex, Tg = 17 ° C)

An average particle diameter of 0.1 μm, a concentration of 45% by mass, an equilibrium water content at 25 ° C. and a relative humidity of 60% 0.6% by mass, and an ionic conductivity of 4.
2 mS / cm (Ion conductivity is measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd., and a latex stock solution (40% by mass) is measured at 25 ° C.), pH 8.2

<< Preparation of Emulsion Layer (Photosensitive Layer) Coating Solution >> 1.1 g of the 20% by mass dispersion of the pigment obtained above, 103 g of each of the silver fatty acid dispersions of A to K, and polyvinyl alcohol PVA-205 (Kuraray)
5 g of a 20% by mass aqueous solution of
5 g, organic polyhalogen compound dispersion-1, -2, -3 at 5: 1: 3
(By weight) 16.3 g, 6.2 g of a 10% by weight dispersion of a mercapto compound, 106 g of 40% by weight of a SBR latex (Tg: 17 ° C.) purified by ultrafiltration (UF) and pH adjusted, and 106 g of a phthalazine compound
Add 18 ml of a 5% by weight solution and add 11 different organic silver salt dispersions.
Various kinds of coating solutions were prepared. Immediately before coating, 10 g of the mixed silver halide emulsion A was mixed well, and the coating solution for the emulsion layer was directly sent to a coating die at 70 ml / m ² and coated.

<< Preparation of Emulsion Surface Intermediate Layer Coating Solution >> A 10% by weight aqueous solution 772 of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.)
g, 20% by weight dispersion of pigment 5.3 g, methyl methacrylate /
Styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 64/9/20/5 /
2) 2 ml of a latex 27.5 mass% solution, 2 ml of a 5 mass% aqueous solution of aerosol OT (manufactured by American Cyanamid Co.), 10.5 ml of a 20 mass% aqueous solution of diammonium phthalate, total amount
Add water to 880 g and NaOH to pH 7.5
And adjusted to 10 ml / m ² to the coating die. The viscosity of the coating solution is a B-type viscometer4
At 0 ° C. (No. 1 rotor, 60 rpm), the value was 21 [mPa · s].

<< Preparation of Coating Solution for First Layer of Emulsion Surface Protective Layer >> 64 g of inert gelatin was dissolved in water, and methyl methacrylate was added.
/ Styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 64/9/20
/ 5/2) 80 g of latex 27.5 mass% liquid, 23 ml of 10 mass% methanol solution of phthalic acid, 10 mass% of 4-methylphthalic acid
23 ml of aqueous solution, 28 ml of 0.5 mol / L sulfuric acid, aerosol
5m 5% aqueous solution of OT (American Cyanamid)
1, 0.5 g of phenoxyethanol and 0.1 g of benzoisothiazolinone were added to make a coating solution by adding water to a total amount of 750 g. / m ² to the coating die. The viscosity of the coating solution was 17 mPa · s using a B-type viscometer at 40 ° C. (No. 1 rotor, 60 rpm).

<< Preparation of Coating Solution for Second Layer of Emulsion Surface Protective Layer >> 80 g of inert gelatin was dissolved in water, and methyl methacrylate was added.
/ Styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer weight ratio 64/9/20
/ 5/2) 102 g of a 27.5% by mass latex liquid, 5% of N-perfluorooctylsulfonyl-N-propylalanine potassium salt
3.2 ml of a 2% by mass solution of polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl-2-aminoethyl) ether [average degree of polymerization of ethylene oxide = 15] is 32 ml, and Aerosol OT (American 23 ml of a 5% by weight solution of Ianamid Co., Ltd., 4 g of polymethyl methacrylate fine particles (average particle size 0.7 μm), 21 g of polymethyl methacrylate fine particles (average particle size 4.5 μm), 1.6 g of 4-methylphthalic acid, 4.8 g of phthalic acid, Water was added to a total of 650 g in 44 ml of 0.5 mol / L sulfuric acid and 10 mg of benzoisothiazolinone, and 445 ml of an aqueous solution containing 4% by mass of chromium alum and 0.67% by mass of phthalic acid was applied immediately before application. 8.3m
The solution was fed to the coating die so as to be l / m ² . The viscosity of the coating solution was 9 mPa with a B-type viscometer at 40 ° C (No. 1 rotor, 60 rpm).
[S].

<< Preparation of Photothermographic Material >> On the back surface side of the undercoating support, an antihalation layer coating solution was applied so that the coating amount of the solid fine particle dye was 0.04 g / m ² and the back surface was protected. The layer coating solution was simultaneously layer-coated so that the coated amount of gelatin became 1.7 g / m ^2, and dried to form a back layer. Emulsion layer (silver halide coated silver amount 0.14 g / m ² ), intermediate layer, first protective layer,
Samples No. 1 to 11 of the photothermographic material were prepared by simultaneous multi-layer coating using a slide bead coating method in the order of the protective layer second layer. 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 reduced pressure 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 solution is cooled by air having a dry-bulb temperature of 10 to 20 ° C., and is then 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, the humidity was adjusted at 25 ° C. at a relative humidity of 40 to 60%, and the film surface was heated to 70 to 90 ° C. After heating, the film surface was cooled to 25 ° C.

[0210] The matte degree of the produced photothermographic material was 550 seconds on the photosensitive layer side and 130 seconds on the back side in Bekk smoothness. Also, when the pH of the film surface on the photosensitive layer side was measured,
6.0.

[0211]

Embedded image

[0212]

Embedded image

(Evaluation of photographic performance) Exposure of photographic materials using Fuji Medical Dry Laser Imager FM-DPL (with a 660 nm semiconductor laser with a maximum output of 60 mW (IIIB))
After heat development (about 120 ° C.), the obtained image was evaluated with a densitometer. The density of the unexposed portion was defined as fog, and the reciprocal of the ratio of the exposure amount giving a density 2.0 higher than the fog was defined as sensitivity. The results are shown in Table 1. The sensitivity was relative to the sensitivity of sample No. 1 as 100. (Evaluation of photographic performance after aging) Sample
After leaving Nos. 1 to 11 in an environment of 50 ° C. and a relative humidity of 60% for 10 days, the photographic performance was evaluated. Table 1 shows fog and relative sensitivity.

[0214]

[Table 1]

As is clear from Table 1, it is understood that Sample Nos. 10 and 11, which correspond to the present invention, have low fog, high sensitivity, and little change in photographic performance over time.

Example 2 A photothermographic material sample No. 12 was prepared in the same manner as in Sample No. 11 except that the coating solution for the emulsion layer was changed as follows, and evaluated in the same manner as in Example 1. An effect equivalent to that of sample No. 11 was confirmed. << Preparation of coating solution for emulsion layer (photosensitive layer) >>
1.1 g of a 20% by mass aqueous dispersion, 103 g of a fatty acid silver dispersion, 5 g of a 20% by mass aqueous solution of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 26 g of a 25% by mass dispersion of the above reducing agent complex, 26 g of organic polyhalogen Compound dispersion-3, -4 in 1: 3 (weight ratio), total amount 8.2
g, 10% dispersion of mercapto compound, 6.2 g, ultrafiltration (UF) purified and pH adjusted SBR latex (PL-5Tg: 24 ° C) 40% by mass
106 g and 18 ml of a 5% by mass solution of a phthalazine compound were added. Immediately before coating, an emulsion layer coating solution in which 10 g of silver halide mixed emulsion A was mixed well was directly applied to a coating die at 70 ml / m2.
^The solution was fed so as to be ² and applied.

[0219]

By using the dispersion of the silver salt of an organic acid prepared by the method of the present invention, a photothermographic material having low fog, high sensitivity and little change in photographic performance over time can be produced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one configuration example of an apparatus used for performing an ultrafiltration process.

[Description of Signs] 1 Tank 2 Circulation Pump 3 Ultrafiltration Module 4 Flowmeter for Replenished Pure Water Measurement 5 Flowmeter for Permeated Water Measurement 6 Pump for Reverse Washing

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B01F 17/02 B01F 17/02 17/32 17/32 17/42 17/42 17/48 17 / 48 17/52 17/52 F term (reference) 2H123 AB00 AB03 AB25 AB28 BA00 BA14 BC00 BC01 BC12 CB00 CB03 4D006 GA06 HA01 HA41 HA61 KA02 KD04 KE11Q KE19Q MA01 MA03 MB05 PA03 PB15 PB27 PC41 4D077 AA06 AB20 DC05 DC03X DD08X DD12X DD15X DD65X DE16X 4G065 AA01 AA05 AB09X AB16X AB22X BA03 BA07 BB01 CA11 DA09 EA01 EA02 FA01

Claims (11)

[Claims] 1. A method for producing a dispersion of silver salt of an organic acid, comprising the following steps: (1) One kind of an ionic surfactant having an anionic hydrophobic group having 8 to 40 carbon atoms Introducing the above into the reaction solution in an amount exceeding 1 mol% with respect to the silver salt of the organic acid before the start of the formation of the silver salt of the organic acid and before ultrafiltration after the formation of the silver salt; (2) Ultrafiltration is performed using a membrane having a molecular weight cutoff of 10 to 50 times the molecular weight of the ionic surfactant, and the amount of the ionic surfactant in the reaction solution after the ultrafiltration is determined using an organic acid. A step of making the ultrafiltrate obtained in the step (2) mechanically dispersed by a disperser; 2. A solution containing silver ions in (a) water or a mixed solution of an organic solvent and water, and (b) water, a mixed solution of an organic solvent and water, or an alkali of an organic acid in an organic solvent. The method according to claim 1, further comprising the step of reacting a solution or suspension containing a metal salt to form the organic silver salt particles. 3. A polymer dispersant, which is nonionic and has a molecular weight of 5 to 50 times the molecular weight cut-off of the membrane used for ultrafiltration, after the formation of the silver salt of the organic acid and before the ultrafiltration operation 3. The method according to claim 1, further comprising the step of: 4. The ionic surfactant according to claim 1, wherein the hydrophilic group is a sulfonate or a sulfate, and is a hydrophilic group having at least one aromatic group. The method described in. 5. An ultrafiltration operation is further performed prior to adding the nonionic polymer dispersant, and the electric conductivity at the time of adding the nonionic polymer dispersant is less than 2,000 μS / cm. The method according to claim 3. 6. The method according to claim 3, wherein the concentration of the nonionic polymer dispersant is 0.1 to 30% by mass of the organic acid silver salt (solid content). 7. The dispersant according to claim 3, wherein the nonionic polymer dispersant is one or more dispersants selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone, and hydroxypropylcellulose. Method. 8. After adding a nonionic polymer dispersing agent, it is doubled.
The method according to any one of claims 3 to 7, further comprising a step of concentrating the dispersion to a concentration of 10% by mass to 50% by mass after performing a 20-fold constant volume dilution. 9. A method for producing a photothermographic material comprising a photosensitive silver halide, a silver salt of an organic acid, a reducing agent for silver ions, and a binder on at least one surface of a support, the method comprising the steps of: 9. A method comprising using an organic acid silver salt produced by the method according to any one of items 8 to 8. 10. An image-forming layer containing a photosensitive silver halide and a silver salt of an organic acid has a binder of 25 ° C. and a relative humidity of 6 ° C.
A polymer having an equilibrium water content at 0% of 2% by mass or less,
The method according to claim 9, further comprising a step of applying the image forming layer using a coating liquid in which 30% by mass or more of a solvent is water. 11. A photothermographic material produced by the method according to claim 9. Description: