JP2007316276A - Apparatus and method for producing organic silver salt particles, silver salt photothermographic dry imaging material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production apparatus and method by which fine organic silver having a monodisperse particle size distribution can be formed and uniformly dispersible organic silver less liable to generate fog is produced, a dry imaging material using the organic silver, and an image forming method using the dry imaging material. <P>SOLUTION: In the apparatus for producing organic silver salt particles in which a silver ion-containing solution prepared using at least water or a mixture of water and an organic solvent as a solvent is mixed with a solution or suspension of an alkali metal salt of an organic acid prepared using water, an organic solvent or a mixture of water and an organic solvent as a solvent to form organic silver salt particles, a static mixer is disposed to which a plurality of supply pipes for supplying the two liquids and a mixing discharge pipe for mixing and discharging the liquids have been connected in such a way that the axes of the supply pipes and the axis of the mixing discharge pipe corss at one place and these axes get together at the cross-point, wherein the static mixer has a vibration applying means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing organic silver salt particles, a method for producing organic silver salt particles, a silver salt photothermographic dry imaging material (hereinafter also referred to as dry imaging material) using the organic silver salt particles, and a dry imaging material. The present invention relates to the image forming method used.

  In recent years, imaging (image forming) materials have been required to satisfy not only performance such as sensitometry characteristics, image quality characteristics, and ease of handling, but also safety and environmental preservation. In particular, since the ocean dumping of development processing waste liquid has been completely banned, the need from wet processing to dry processing has become remarkable in the fields of medical treatment and printing plate making.

  On the other hand, in the medical field, due to recent digitization of medical information, medical diagnosis images have become mainstream techniques such as MRI (Magnetic Resonance Imaging), CT (Computed Tomography), CR (Computed Radiography), etc. A dry imager system for medical imaging has been used. In the field of printing plate making, similar digitization and drying are progressing.

  Along with the above-mentioned social and market trends, photothermographic dry imaging materials that are capable of efficient exposure, such as laser imagers and laser imagesetters, and that can form clear images with high resolution. With increasing importance, there is a need for further improvements in the material.

  Examples of the technique relating to the photothermographic dry imaging material include D.I. Morgan and B.M. U.S. Pat. Nos. 3,152,904, 3,487,075 by Shely or D.C. H. As described in “Dry Silver Photographic Materials” by Klosterboer (Handbook of Imaging Materials, Marcel Dekker, Inc., page 48, 1991) and the like. Dry imaging materials containing a silver salt, photosensitive silver halide grains and a silver ion reducing agent are known. Since this dry imaging material does not use any solution processing chemicals in the development processing, it has an advantage that it can provide a user with a simpler system that does not impair the environment.

  These dry imaging materials use photosensitive silver halide grains installed in the photosensitive layer as a photosensor, use an organic silver salt as a silver ion supply source, and usually at 80 to 140 ° C. depending on a built-in reducing agent. An image is formed by heat development, and fixing is not performed.

  However, since the dry imaging material contains an organic silver salt, photosensitive silver halide grains, and a reducing agent, fog is likely to occur during the storage period before heat development. In addition, after exposure, it is usually only heat developed at 80 to 140 ° C., and fixing is not performed. Therefore, all or part of silver halide grains, organic silver salt, reducing agent, etc. remain even after heat development. There is a problem that metal silver is generated by heat or light during a long-term storage process, and the image quality such as the color tone of the silver image is likely to change.

  Various methods for preparing an organic silver salt as a silver supplier used in a dry imaging material are known. For example, a method for preparing an organic silver salt in a coexisting solution of water and a poorly water-soluble solvent, such as JP-A-49-93310, JP-A-49-94619, and JP-A-53-68702, No. 57-186745, No. 47-9432, and US Pat. No. 3,700,458, etc., a method for preparing an organic silver salt in an organic solvent, Japanese Patent Application Laid-Open No. 53-31611, Methods for preparing an organic silver salt in an aqueous solution described in JP-A Nos. 54-4117, 54-46709, and US Pat. No. 5,434,043 are known.

  On the other hand, in order to provide dry imaging materials with light sensitivity, a method of incorporating silver halide into a heat developing material is widely known. This silver halide is based on a conventional aqueous silver halide gelatin emulsion method. It is very advantageous from the viewpoint of ease of introduction of techniques such as size control, crystal wall control, impurity doping, and chemical ripening. However, when preparing an organic silver salt in the presence of an organic solvent, or when preparing an organic silver salt in an organic solvent, the silver halide made hydrophilic by such gelatin must be uniformly dispersed in the organic silver salt. Is difficult, and it is very difficult to obtain desired Dmax and sensitivity in terms of photographic characteristics. Therefore, generally, a method of adding silver halide at the stage of preparing an organic silver salt with an aqueous solution is employed. In this sense, the organic silver salt is advantageously prepared in an aqueous solution.

  As a method for preparing an organic silver salt dispersion in an aqueous solution, a fatty acid is dissolved in water at or above its melting point, and a sodium salt is formed there. Thereafter, the emulsion is added when the temperature is lowered, and silver nitrate is further added to form an organic silver salt dispersion. However, when the temperature is lowered before the addition of silver nitrate, the viscosity of the liquid increases rapidly, and the viscosity also increases when organic silver is formed by the addition of silver nitrate. At that time, if the liquid is not uniformly stirred at a high speed, the formation of organic silver becomes non-uniform, and not only monodispersed and fine organic silver can not be formed, but also fog and the like tend to increase, resulting in production. The heat-developable coating film thus produced has caused undesirable problems in performance.

  In response to these problems, Japanese Patent Application Laid-Open No. 2000-143578 discloses a high-speed organic silver salt dispersion that generates and disperses an organic silver salt by adding silver nitrate to an aqueous solution or suspension of an alkali salt of an organic acid. A method of manufacturing with a manufacturing apparatus having a gas / liquid interface provided with a rotary centrifugal radiation type stirrer or a high speed rotary shear type stirrer is described. An example of a production apparatus using a conventional high-speed rotary centrifugal radiation type stirrer (disperser) having a gas / liquid interface will be described with reference to FIG.

FIG. 4 is a schematic view of a conventional organic silver salt production apparatus having a gas / liquid interface.
In the figure, reference numeral 2 denotes an apparatus for producing an organic silver salt having a gas / liquid interface 205. The production apparatus 2 includes a reaction apparatus main body 201, a stirring member 202 that rotates along the inner wall 201 a and the bottom 201 b of the reaction apparatus main body 201, a high-speed rotating centrifugal radiation stirrer (disperser) 203, and the reaction apparatus main body 201. It has a jacket 204 for controlling the temperature and a supply pipe 206 for a silver ion-containing solution prepared using water or a mixture of water and an organic solvent as a solvent. It is preferable that at least two high-speed rotating centrifugal radiation stirrers (disperser) 203 are provided. The rotation directions of the stirring member 202 and the high-speed rotating centrifugal radiation stirrer (disperser) 203 are preferably opposite to each other. A high-speed rotating radial radial stirrer (disperser) is a toothed disk-shaped impeller with circular saw blades bent up and down alternately, causing vortex flow in the liquid and causing powder to flow in the liquid. At the same time, it is a stirrer that atomizes powder agglomerates by the cutting action of the peripheral teeth.

  When an organic silver salt is produced using the production apparatus shown in the figure, an organic acid alkali metal salt solution or suspension prepared using water, an organic solvent, or a mixture of water and an organic solvent in the reaction apparatus main body 201 as a solvent. It is manufactured by supplying a silver ion-containing solution from a supply pipe 206 while stirring the turbid liquid with a stirring member 202 and a high-speed rotary centrifugal radiation type stirrer (disperser) 203.

  When producing an organic silver salt using the production apparatus shown in this figure, coarsening of the organic silver salt particles is prevented by high-speed stirring, but when added to a tank having a gas / liquid interface, stirring is performed. Increasing speed causes air entrainment. The fatty acid silver salt particles are extremely hydrophobic and adsorb on the surface of the entrained foam to stabilize the foam and prevent bubble breakage, and adjacent particles on the foam cause aggregation. In this way, the liquid in which the air is entrained becomes a whipped cream, and when desalting the by-product salt by ultrafiltration or the like, not only the handling property is remarkably deteriorated but also the aggregated particles cause clogging. . In addition, the produced organic silver salt particles have a non-uniform granularity and have a drawback of poor storage applicability.

  An organic silver production apparatus and method that can form monodispersed and fine organic silver and suppress fogging without using such a production apparatus having an air / liquid interface has been studied. For example, organic silver salt particles, a solution of silver ions containing water or a mixture of water and an organic solvent as a solvent, and a fatty acid alkali metal salt solution containing water, an organic solvent or a mixture of water and an organic solvent as a solvent Are known to be prepared by mixing and reacting in a closed mixing means having no gas / liquid interface (see, for example, Patent Documents 1, 2, and 3). However, although the methods described in Patent Documents 1, 2, and 3 exhibit a certain effect, the hermetic mixing means has an agitation means inside, and therefore the structure becomes complicated and microscopically seen. In such a case, problems such as liquid stagnation cannot be ignored. In the closed continuous mixing method, the retention of the liquid not only disturbs the particle size and distribution of the organic silver salt particles, but also increases the fog due to exposure of the retained particles to a high concentration of silver ions. There is a danger of causing problems to say.

  In addition, silver ion-containing solution using organic silver salt particles as a solvent, or a mixture of water and an organic solvent, and a solution of fatty acid alkali metal salt using water, an organic solvent or a mixture of water and an organic solvent as a solvent. Is prepared by mixing and reacting using a micromixer (see, for example, Patent Document 4). However, the micromixer used in the method described in Patent Document 4 is static mixing that does not have a stirring means inside, and specifically, is a device that performs the inside of a microchannel in a laminar flow state. The laminar flow refers to a flow in which each particle of the fluid moves in parallel in the flow direction. For this reason, nuclei cannot be generated in a uniform state unless the concentration of the additive solution is low. Accordingly, the particle size distribution of the organic silver salt particles is deteriorated, there is a risk of fog increase, and there is a risk that productivity is deteriorated because the additive solution is lowered in concentration, and the additive solution is sent into a micro flow path to form a laminar flow. .

Under such circumstances, the production apparatus, production method, and organic silver for producing organic silver having a monodisperse particle size distribution, capable of forming fine organic silver, and having a uniform dispersion and less fogging are used. Development of a dry imaging material and an image forming method using the dry imaging material has been desired.
JP 2001-33907 A Japanese Patent Laid-Open No. 2001-83652 JP 2002-31870 A JP 2003-43607 A

  The present invention has been made in view of the above circumstances, and its purpose is to produce organic silver that has a monodisperse particle size distribution, can form fine organic silver, and has a uniform dispersion and less fog. An apparatus, a manufacturing method, a silver salt photothermographic dry imaging material using the organic silver, and an image forming method using the silver salt photothermographic dry imaging material.

  The above object of the present invention has been achieved by the following constitution.

  1. A silver ion-containing solution prepared using at least water or a mixture of water and an organic solvent as a solvent, and an organic acid alkali metal salt solution or suspension prepared using water, an organic solvent, or a mixture of water and an organic solvent as a solvent. In an apparatus for producing organic silver salt particles, wherein two liquids are mixed to produce organic silver salt particles, the shafts of a plurality of supply pipes of the two liquids and the shafts of the mixed discharge pipes for mixing and discharging them are at one place. It has a static mixing device to which the supply pipe and the mixing discharge pipe are connected so that the axes intersect at the intersection, and the static mixing device has vibration applying means. Organic silver salt particle manufacturing equipment.

  2. 2. The apparatus for producing organic silver salt particles as described in 1 above, wherein the vibration applying means is an ultrasonic generator.

  3. A silver ion-containing solution prepared using at least water or a mixture of water and an organic solvent as a solvent, and an organic acid alkali metal salt solution or suspension prepared using water, an organic solvent, or a mixture of water and an organic solvent as a solvent. In the method for producing organic silver salt particles, wherein the two liquids are mixed to form organic silver salt particles, the mixing of the two liquids is performed by mixing a plurality of supply pipe shafts of the two liquids and a mixed discharge pipe for mixing and discharging them. It is carried out while applying vibration by a static mixing device having vibration applying means to which the supply pipe and the mixed discharge pipe are connected so that the axis intersects at one place and the axis coincides at the intersection. A method for producing organic silver salt particles.

  4). 4. The method for producing organic silver salt particles as described in 3 above, wherein the vibration applying means is an ultrasonic generator.

  5. A photosensitive layer containing photosensitive silver halide grains, a reducing agent capable of reducing silver ions, a binder, and organic silver salt particles produced by the method for producing organic silver salt particles described in 3 or 4 above on a support. A silver salt photothermographic dry imaging material characterized by comprising:

  6). An image forming method based on digital image information, wherein a silver image is formed using the silver salt photothermographic dry imaging material described in 5 above.

  Monolithic particle size distribution, fine organic silver can be formed, uniform dispersion and production of organic silver with little fogging, manufacturing method, silver salt photothermographic dry imaging using the organic silver Materials and image forming methods using silver salt photothermographic dry imaging materials can be provided, with improved production efficiency due to stable production of organic silver, and high quality and stable performance of silver salt photothermographic dry imaging materials The production volume can be increased.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited thereto.

  FIG. 1 is a schematic view of an apparatus for producing organic silver salt particles of the present invention. FIG. 1 (a) is a schematic view of an apparatus for producing organic silver salt particles in which a vibration means is provided in a static mixing apparatus. FIG. 1B is an enlarged schematic view of a portion indicated by T in FIG.

  In the figure, 1 indicates a manufacturing apparatus. The manufacturing apparatus 1 includes a first preparation tank 11, a second preparation tank 12, a static mixing device 13, a first heat exchanger 14a, a second heat exchanger 14b, and a storage tank 15. Yes. In the first preparation tank 11, a silver ion-containing solution is prepared using at least water or a mixture of water and an organic solvent as a solvent. 11a shows the jacket for temperature adjustment, 11b shows a stirrer.

  In the second preparation tank 12, an organic acid alkali metal salt solution or suspension is prepared using water, an organic solvent, or a mixture of water and an organic solvent as a solvent. 12a shows the jacket for temperature adjustment, 12b shows a stirrer. Of course, the organic acid alkali metal salt solution or suspension may be prepared in the first preparation tank 11, and the silver ion-containing solution may be prepared in the second preparation tank 12.

  The silver ion-containing solution prepared in the first preparation tank 11 is sent to the static mixing device 13 via the flow rate detector 11d by the liquid feed pump 11c. The liquid feed pump 11c can control the flow rate according to the survey result from the flow rate detector 11d.

  The organic acid alkali metal salt solution or suspension prepared in the second preparation tank 12 is sent to the static mixing device 13 via the flow rate detector 12d and the first heat exchanger 14a by the liquid feed pump 12c. . The liquid feed pump 12c can control the flow rate according to the survey result from the flow rate detector 12d.

  By controlling the amount of liquid fed from the first preparation tank 11 and the second preparation tank 12, it is possible to maintain a certain reaction condition and suppress side reactions.

  The silver ion-containing solution prepared in the first preparation tank 11 is silver nitrate. The silver ion concentration of the silver ion-containing solution is preferably 0.015% by mass in consideration of reactivity and the like. More preferably, it is 0.02 mass%. The viscosity is preferably 1 to 5 mPa · s in consideration of reactivity and the like. The temperature is preferably 40 to 70 ° C. in consideration of reactivity and the like.

  The concentration of the organic acid alkali metal salt solution or suspension prepared in the second preparation tank 12 is preferably 0.1 to 30% by mass, more preferably 1 in consideration of reactivity, mixing properties, and the like. -10 mass%. The viscosity is preferably 1 to 100 mPa · s in consideration of reactivity, mixing properties, and the like.

  It is considered that the organic acid alkali metal salt solution or suspension is preferably maintained at 60 ° C. or higher in order to avoid crystallization and solidification in the second preparation tank 12. However, the organic acid alkali metal salt solution or suspension is rapidly cooled from the high temperature (70 ° C. to 100 ° C.) to the low temperature (30 ° C. to 60 ° C.) by the first heat exchanger 14a without crystallization and solidification. It is possible to reduce the viscosity. The first heat exchanger 14a is not particularly limited as long as the temperature can be lowered from a high temperature (70 ° C. to 100 ° C.) to a low temperature (30 ° C. to 60 ° C.). For example, multi-tubular heat exchanger, heat pipe heat exchanger, double pipe heat exchanger, coil heat exchanger, cascade heat exchanger, plate heat exchanger, swirl plate heat exchanger, water A cold heat exchanger can be used.

  Examples of the flow rate detector 11d (12d) include a detector that detects volume, a method that detects mass, and the like, but a mass detector that is not affected by volume change due to liquid temperature fluctuation is preferable. A solution or suspension of an alkali metal salt of an organic acid and a solution containing silver ions containing silver ions that can exchange with an alkali metal of an organic acid alkali metal salt are simultaneously weighed and statically mixed according to the design recipe. It is desirable to be supplied to the device 13. Here, the simultaneous weighing means that at least 50% or more of each of the solution or suspension of the organic acid alkali metal salt and the silver ion-containing solution is simultaneously weighed, and a preset amount is supplied to the static mixing device 13. The amount weighed at the same time is preferably 80% or more, more preferably 90% or more. The preset amount means that the solution or suspension of the organic acid alkali metal salt and the silver ion-containing solution are uniformly mixed by applying vibration by the vibration means 13d disposed in the static mixing device 13. An amount that enables the production of organic silver salt particles in a steady state.

  In the static mixing device 13, the silver ion-containing solution sent from the first preparation tank 11 and the organic acid alkali metal salt solution or suspension sent from the second preparation tank 12 are mixed to obtain an organic silver salt. Particles (also referred to as organic acid silver particles) are generated. A static mixing device refers to a device that mixes a plurality of reaction solutions without intentional physical stirring by a stirrer during an initial period in which the plurality of solutions come into contact with each other for the first time and are mixed. .

  The static mixing device 13 includes a supply pipe 13a for the silver ion-containing solution sent from the first preparation tank 11, and a supply pipe for the organic acid alkali metal salt solution or suspension sent from the second preparation tank 12. 13b, a mixed discharge pipe 13c that discharges the mixed liquid in which these two liquids are mixed to produce organic silver salt particles, and a vibration means 13d that vibrates the static mixing device 13. The static mixing device 13 is configured so that the axes of the supply pipe 13a and the supply pipe 13b and the axis of the mixture discharge pipe 13c are on one plane and intersect at one place, and the axes coincide at the intersection P. 13a, the supply pipe 13b, and the mixed discharge pipe 13c are connected. L indicates the inner length of the mixed discharge pipe 13c.

  The ratio of the inner diameters of the supply pipe 13a, the supply pipe 13b, and the mixed discharge pipe 13c can be arbitrarily changed, but is preferably 1: 1: 1 in consideration of the mixing property.

  The inner diameter of the mixed discharge pipe 13c is preferably 1 mm or more and 100 mm or less in consideration of the liquid feeding speed, the mixing property, the productivity, the pressure loss in the piping, and the like. It is important to select an appropriate inner diameter from the supply pipe 13a and the supply pipe 13b as appropriate from the amount of layer feeding.

The lengths of the supply pipes 13a and 13b are preferably 3 mm to 100 mm in consideration of piping pressure, flow rate stability, and the like.
The inner length of the mixed discharge pipe 13c is preferably longer than the length obtained from the calculation according to the following formula A.

Formula A: L = k · D−N
Here, L: inner length [mm] of the mixed discharge pipe, k: constant (= 69.907), D: inner diameter [mm], and N: constant (= 1.682).

  Here, “the length of the inside of the mixed discharge pipe” is a coincidence point where the axes coincide at an intersection P where the axis of the mixed discharge pipe, the axis of the supply pipe 13a, and the axis of the supply pipe 13b intersect at one place. To the length until the two liquids passing through the supply pipe 13a and the supply pipe 13b are discharged from the mixed discharge pipe. About calculation by A type | formula, it is possible to calculate based on the simulation result using the structural analysis and fluid simulation software (COSMOS Flows). Specifically, it is possible to obtain the complete mixing condition of the static mixer (the length at which the two liquids are completely mixed in the mixing discharge pipe) from the relationship between the inner diameter of the mixing discharge pipe and the length of the discharge pipe.

  The axis of the supply pipe 13a and the supply pipe 13b and the axis of the mixed discharge pipe 13c intersect at one place, and the axes coincide at the intersection P. When all the pipe axes converge at one place, one intersection Are not limited to a desirable mode in which the axes coincide with each other, and include those having an axis misalignment within 10% of the inner diameter of the thickest pipe among the pipes to be connected.

  The joining of the supply pipe 13a, the supply pipe 13b, and the mixed discharge pipe 13c is not particularly limited as long as the axes of all the pipes are gathered at one place and the axes coincide at one intersection as described above. As a particularly preferable joint, the axis of the supply pipe 13a and the supply pipe 13b and the axis of the mixed discharge pipe 13c are on the same plane and symmetrically intersect with the axis of the mixed discharge pipe 13c at almost one point. Various types of joining are mentioned. This figure has shown the case where the axis | shaft of the supply pipe | tube 13a, the supply pipe | tube 13b, and the mixing discharge pipe | tube 13c exists on the same plane (refer the static mixing apparatus shown to (a) of FIG. 2). As described above, the shafts of all the tubes are gathered in one place. At this time, the inter-axis angle θ1 between the supply tube 13a and the supply tube 13b depends on the mixing property in the mixed discharge tube 13c and the complete reaction at the time of particle formation. In consideration of the length of the mixing distance, formation of fog nuclei, fluid pressure loss, flow rate balance, etc., it is preferably 90 ° or more and less than 180 °.

  Further, the angle θ2 between the shafts of the supply pipe 13a and the supply pipe 13b and the mixed discharge pipe 13c is preferably set to 90 ° or more and 135 ° or less. Accordingly, the angle can be arbitrarily adjusted and the optimum angle can be selected. Note that the angles θ1 and θ2 represent inner angles.

  In the static mixing device 13 shown in this figure, the supply pipe 13a of the silver ion-containing solution sent from the first preparation tank 11 and the organic acid alkali metal salt solution or suspension sent from the second preparation tank 12 are used. The liquid is controlled by the flow rate detector 11d (12d) and supplied in a predetermined amount, and is uniformly mixed by being vibrated by the vibrating means 13d. The organic silver salt particles generated in the mixing and discharging pipe 13c are immediately Since it is discharged from the discharge pipe, it is possible to generate organic silver salt particles in a steady state.

  It is preferable that the vibration means 13d is disposed outside the mixed discharge pipe 13c so that the entire inner length of the mixed discharge pipe 13c can be vibrated. The vibration means 13d is preferably an apparatus capable of applying low-frequency vibration to the static mixing device 13 in consideration of mixing properties. The frequency range is preferably 10 to 30 kHz, and an ultrasonic transmission device is particularly preferable from the standpoint of installation on the device.

  There is no dynamic mixing device inside the supply tube 13a, supply tube 13b and mixing / discharge tube 13c of the static mixing device 13, and the mixing of the silver ion-containing solution and the organic acid alkali metal salt solution or suspension is The collision is caused by the collision of these two liquids at the junction (intersection) of the supply pipe 13a, the supply pipe 13b, and the mixing / discharge pipe 13c, and the vibration of the vibration means 13d provided in the static mixing device 13. Since there is no dynamic mixing device inside the mixing discharge pipe 13c and there is no dead space, uniform mixing is possible and uniform organic silver salt particles can be formed.

  The supply amount of the silver ion-containing solution to be supplied and the flow rate of the organic acid alkali metal salt solution or suspension should be 3 to 10 mol% of the free aliphatic carboxylic acid with respect to the aliphatic carboxylic acid silver salt. It is preferable. Especially preferably, it is made to contain 4-8 mol%. A lower ratio of the aliphatic carboxylic acid silver salt is preferable from the viewpoint of image storage stability.

  The temperature when mixing the silver ion-containing solution and the organic acid alkali metal salt solution or suspension in the static mixing device 13 is 35 ° C. or higher and 70 ° C. or lower in consideration of reactivity, suppression of side reactions, and the like. It is preferable. Furthermore, they are 40 degreeC or more and 65 degrees C or less, More preferably, they are 40 degreeC or more and 60 degrees C or less.

  The amount of silver in the organic silver salt particles at the time when the organic silver salt nuclei are generated by mixing the silver ion-containing solution and the organic acid alkali metal salt solution or suspension greatly affects the monodispersity of the organic silver salt particles. give. Therefore, the amount of silver is 0.0001 mol / L to 0.01 mol / L or less when a silver ion-containing solution and an organic acid alkali metal salt solution or suspension are mixed to generate an organic silver salt nucleus. The upper limit is particularly preferably 0.008 mol / L or less, and most preferably 0.005 mol / L or less.

  In the present invention, it is important that the liquid feed pump 11c (12c) used for mixing the silver ion-containing solution and the organic acid alkali metal salt to generate the organic silver salt nucleus does not have a pulsating flow. When the pulsation of the liquid feed pump 11c (12c) is large, the supersaturation degree of the portion where both the silver ion-containing solution and the organic acid alkali metal salt are mixed periodically fluctuates greatly, and the generated nuclei are uneven. It becomes a thing. This significantly impairs the monodispersity of the produced particles. Therefore, the pulsating flow of the liquid feed pump 11c (12c) to be used is preferably ± 2.0% or less of the average flow rate, more preferably 1.0% or less, and 0.5%. Is particularly preferred.

  In the present invention, the flow rate is measured in units of 1 second, and the arithmetic average thereof is defined as the average flow rate. preferable.

  The state when supplying the silver ion-containing solution from the supply pipe 13a when mixing in the static mixing device 13 and the state when supplying the organic acid alkali metal salt solution or suspension from the supply pipe 13b are particularly limited. However, it is preferably substantially turbulent in terms of preventing backflow or mixing more uniformly. Turbulence is defined by the range of Reynolds number (Re). Here, the Reynolds number is defined as Re = DUρ / η, where D is the typical length of the object in the flow in contact with the fluid, U is the velocity, ρ is the density, and η is the viscosity. The number of dimensions.

  In general, when Re <2100, laminar flow, 2300 <Re <3000, transition region, and Re> 3000 are called turbulent flow. In the present invention, substantially turbulent flow means Re> 3000, preferably Re> 5000, and more preferably Re> 10000.

  In particular, the Reynolds number in the mixed discharge pipe 13c is preferably 5,000 or more as described above from the viewpoint of monodispersity of the particle diameter of organic silver salt particles, fogging, and the like.

In addition, it is preferable from a viewpoint of generation | occurrence | production reduction of fogging that the silver ion index | exponent (pAg) in 25 degreeC of the liquid mixture discharged | emitted from the mixed discharge pipe 23c is 3.5-5.0. Here, the silver ion index is an amount defined by pAg = −log [Ag ⁺ ]. Here, [Ag ⁺ ] represents the silver ion concentration (mol · dm ⁻³ ) in the solution at a specific temperature.

  Using the apparatus for producing organic silver salt particles of the present invention, organic silver salt particles having a sphere equivalent average diameter of organic silver salt particles of 0.1 μm to 0.6 μm have a coefficient of variation of the sphere equivalent average diameter of 25% or less. And the occurrence of fogging can be reduced when the organic silver salt particles according to the present invention are used in a silver salt photothermographic dry imaging material.

  In the 2nd heat exchanger 14b, in order to suppress the particle growth by the Ostwald ripening of the organic silver salt particle | grains produced | generated after mixing, it is possible to cool continuously. The second heat exchanger 14b can use the same heat exchanger as the first heat exchanger 14a.

  In the storage tank 15, a suspension containing organic silver salt particles cooled to the temperature set by the second heat exchanger 14b is stored at 6 to 8 ° C. 15a shows a jacket for adjusting the temperature of the storage tank 15, and 15b shows a stirrer for preventing sedimentation of organic silver salt particles. After a predetermined amount of organic silver salt particles are produced and stored in the storage tank 15, the produced organic silver salt particles are filtered, washed with water (not shown), and dried (not shown). Manufactured.

The following effects can be obtained by producing organic silver salt particles using a static mixing device 13 as shown in the figure.
1) A silver ion-containing solution and an organic acid alkali metal salt solution or suspension are supplied in a controlled manner, and the two liquids are uniformly mixed by a vibrating means to form organic silver salt particles, and then immediately discharged. Therefore, it is possible to produce organic acid silver salt particles having a monodisperse particle size distribution, little fogging, and excellent coating properties.
2) Since there is no dead space in the static mixing device (mixing discharge pipe), uniform mixing is possible and uniform organic silver salt particles can be formed.
3) Since there is no dead space in the static mixing device (mixing discharge pipe), it is difficult to deposit on the inner surface of the mixing discharge pipe, and there is no failure due to peeling of the deposit, and stable production of organic acid silver salt particles Is possible.
4) Since there is no dead space in the static mixing device (mixing discharge pipe), cleaning at the time of product type switching is facilitated, switching in a short time is possible, and production efficiency can be increased.
5) Since it does not have a dynamic mixing device as compared with a conventional closed manufacturing device, the installation area can be reduced, maintenance management can be facilitated, and the cost of the manufacturing device can be reduced.
6) Since there is no gas / liquid interface, organic acid silver salt particles are formed without entrainment of air, and aggregation of organic acid silver salt particles due to bubbles generated by the entrained air, removal of by-product salts Easy handling and desalting during salting.

  FIG. 2 is a schematic perspective view showing an example of the static mixing device shown in FIG. In this figure, the vibration means disposed in the mixed discharge pipe is omitted to show the joined state of the supply pipe and the mixed discharge pipe.

  In the static mixing device shown in FIG. 6A, the axes of the supply pipe 13a, the supply pipe 13b, and the mixing / discharge pipe 13c are in the same plane and symmetrically intersect with the axis of the mixing / discharge pipe 13c at almost one point. The structure is such that the static mixing device shown in FIG. 1 is applicable.

  The static mixing device shown in (b) shows a case where the axes of the supply pipe 13a and the supply pipe 13b are on the same plane and the mixing / discharge pipe 13c is on the other surface. However, the axes of the supply pipe 13a and the supply pipe 13b are joined so that they intersect the axis of the mixed discharge pipe 13c symmetrically at almost one point. The angle formed by the axes of the supply pipe 13a and the supply pipe 13b is the same as that of the static mixing apparatus shown in FIG.

  The static mixing device shown in (c) is in a state where the axes of the supply pipe 13a and the supply pipe 13b are in the same plane with respect to the substantially horizontal mixing / discharge pipe 13c, and the supply pipe 13a and the supply pipe 13b This shows a joined structure in which the axis intersects the axis of the mixed discharge pipe 13c symmetrically at almost one point. The angle formed by the axes of the supply pipe 13a and the supply pipe 13b is the same as that of the static mixing apparatus shown in FIG.

  Although an example of the static mixing apparatus is shown in the figure, the most preferable form among them is the form shown in (a). Next, a dry imaging material using non-photosensitive organic silver salt particles produced by the organic silver salt particle production apparatus shown in FIGS. 1 and 2 will be described.

  FIG. 3 is a schematic cross-sectional view of the dry imaging material of the present invention.

  In the figure, 3 indicates a dry imaging material. The dry imaging material 3 of the present invention includes a photosensitive layer 302 that is at least one image forming layer on a support 301, at least one non-photosensitive layer 303 on the photosensitive layer 302, and a support. In order to prevent “sticking” to the back surface of 301, a back coat layer 304 is provided. As the non-photosensitive layer 303, for example, a protective layer is preferably provided for the purpose of protecting the photosensitive layer 302, and the non-photosensitive layer 303 can be laminated as necessary. The non-photosensitive organic silver salt grains produced in FIG. 1 that can function as a source for supplying silver ions to the photosensitive layer 302 are used with the photosensitive silver halide grains. For gradation adjustment or the like, two or more photosensitive layers may be provided on one side of the support or one or more layers on both sides of the support.

  Hereinafter, materials used for producing non-photosensitive organic silver salt particles using the organic silver salt particle production apparatus of the present invention shown in FIGS. 1 and 2 will be described.

(Organic acid)
The organic acid alkali metal salt used in the organic acid alkali metal salt solution or suspension will be described. The organic acid alkali metal salt refers to an organic acid alkali metal salt formed by an organic acid and an alkali metal. An organic acid refers to an organic compound that exhibits acidity. Examples thereof include compounds having an acidic functional group such as carboxylic acid, sulfonic acid, sulfinic acid, phenol, enol, thiol, acid imide, oxime, and sulfonamide. Of these, carboxylic acids are preferred in the present invention. In particular, aliphatic carboxylic acids, that is, fatty acids are preferred. Further, a long chain aliphatic carboxylic acid is preferable, and the carbon number is preferably 10 to 30, more preferably 10 to 26. For example, behenic acid, stearic acid, arachidic acid, palmitic acid, lauric acid and the like are preferable. As long-chain aliphatic carboxylic acids. The organic acid may be a single composition or a mixed composition. In the case of a mixed composition, the proportion of the main composition in the mixture is preferably 80 mol% or more, more preferably 90 mol% or more.

  On the other hand, from the standpoint of image storability after development, the aliphatic carboxylic acid silver salt, which is a raw material of the aliphatic carboxylic acid silver salt, has a melting point of 50 ° C. or higher, preferably 60 ° C. or higher. Is preferably 50% or more, preferably 70% or more, and more preferably 80% or more. From this viewpoint, specifically, it is preferable that the content of silver behenate is high.

(Alkali metal compound)
Examples of types of alkali metal compounds that can be used to make organic acid alkali metal salts include sodium hydroxide, potassium hydroxide, lithium hydroxide, and the like. Among these, it is preferable to use one kind of alkali metal compound, for example, potassium hydroxide, but it is also preferable to use sodium hydroxide and potassium hydroxide in combination, and the molar ratio is 10:90 to 75: A range of 25 is preferred. When used in the above range when reacted with an aliphatic carboxylic acid to form an alkali metal salt of an aliphatic carboxylic acid, the viscosity of the reaction solution can be controlled to be in a good state.

(Organic acid alkali metal salt)
The organic acid alkali metal salt is prepared by adding the aforementioned alkali metal compound to the aforementioned organic acid. At this time, the amount of the alkali metal compound is preferably made equal to or less than the equivalent amount of the organic acid to leave the unreacted organic acid. In this case, the amount of residual organic acid is preferably 1 to 50 mol%, more preferably 1 to 30 mol%, based on the total organic acid. Or after adding an alkali more than a desired quantity, you may prepare by adding acids, such as nitric acid and a sulfuric acid, and neutralizing an excess alkali content.

(Organic silver salt particles (organic acid silver salt particles))
The organic silver salt particles (organic acid silver salt particles) produced by the apparatus for producing organic silver salt particles shown in FIG. 2 of the present invention can be used for various purposes and applications, and an example thereof is shown in FIG. Examples include dry imaging materials. When used as a dry imaging material, it can be used as a non-photosensitive organic silver salt that can function as a supply source for supplying silver ions for forming a silver image.

  That is, when used in a dry imaging material, the organic silver salt according to the present invention is a photosensitive silver halide grain (photocatalyst) having a latent image formed by exposure on the grain surface and a reducing agent. In the heat development process heated to 80 ° C. or higher, it can be used as a silver salt that functions as a silver ion supply source and supplies silver ions to contribute to silver image formation. In addition, it is preferable that two or more organic acid silver salts are mixed in order to improve developability and form a high-concentration and high-contrast silver image. For example, a solution containing silver ions in a mixture of two or more organic acids. It is possible to prepare by mixing.

  The organic acid silver salt particles (aliphatic carboxylic acid silver salt particles) according to the present invention are a mixture of a free aliphatic carboxylic acid and an aliphatic carboxylic acid silver salt that do not form a silver salt. Specifically, By determining the total aliphatic carboxylic acid amount and the free aliphatic carboxylic acid amount by the following methods, respectively, the aliphatic carboxylic acid silver salt and the free aliphatic carboxylic acid amount and their respective ratios or the free amount relative to the total aliphatic carboxylic acid The ratio of fatty acids can be calculated.

(Quantification of total aliphatic carboxylic acid content (total of those derived from both the above aliphatic carboxylic acid silver salts and free acids))
(1) About 10 mg of sample (the mass removed when peeling from the photosensitive material) is accurately weighed and placed in a 200 ml eggplant type flask.
(2) Add 15 ml of methanol and 3 ml of 4 mol / L hydrochloric acid and ultrasonically disperse for 1 minute.
(3) Put a Teflon (registered trademark) zeolite and reflux for 60 minutes.
(4) After cooling, add 5 ml of methanol from the top of the cooling tube, and wash the material adhering to the cooling tube into the eggplant-shaped flask (twice).
(5) The obtained reaction solution is extracted with ethyl acetate (100 ml of ethyl acetate and 70 ml of water are added and liquid separation extraction is performed twice).
(6) Vacuum dry at room temperature for 30 minutes.
(7) Add 1 ml of benzanthrone solution as an internal standard to a 10 ml volumetric flask (dissolve about 100 mg of benzanthrone in toluene and make up to 100 ml with toluene).
(8) Dissolve the sample in toluene and put it in the volumetric flask of (7), and make a constant volume with toluene.
(9) Perform gas chromatography (GC) measurement under the following measurement conditions.

Apparatus: HP-5890 + HP-Chemical station Column: HP-1 30 m × 0.32 mm × 0.25 μm (manufactured by HP)
Inlet: 250 ° C
Detector: 280 ° C
Oven: constant 250 ° C. Carrier gas: He
Head pressure: 80 kPa
[Quantification of free aliphatic carboxylic acid content]
(1) About 20 mg of a sample is accurately weighed, placed in a 200 ml eggplant-shaped flask, 10 ml of methanol is added, and ultrasonic dispersion is performed at 25 ° C. for 1 minute (free organic carboxylic acid is extracted).
(2) It is filtered, and the filtrate is put into a 200 ml eggplant type flask and dried (free organic carboxylic acid is separated).
(3) Add 15 ml of methanol and 3 ml of 4 mol / L hydrochloric acid and perform ultrasonic dispersion for 1 minute.
(4) Put a Teflon (registered trademark) boiling stone and reflux for 60 minutes.
(5) 60 ml of water and 60 ml of ethyl acetate are added to the resulting reaction solution, and the methyl esterified product of organic carboxylic acid is extracted into the ethyl acetate phase. Ethyl acetate extraction is performed twice.
(6) The ethyl acetate phase is dried and vacuum dried for 30 minutes.
(7) Add 1 ml of benzanthrone solution (internal standard: about 100 mg of benzanthrone dissolved in toluene to a constant volume of 100 ml) in a 10 ml volumetric flask.
(8) Dissolve (6) with toluene, put into the volumetric flask of (7), and make a constant volume with toluene.
(9) Perform GC measurement under the following measurement conditions.

Apparatus: HP-5890 + HP-Chemical station Column: HP-1 30 m × 0.32 mm × 0.25 μm (manufactured by HP)
Inlet: 250 ° C
Detector: 280 ° C
Oven: constant 250 ° C. Carrier gas: He
Head pressure: 80 kPa
[Structure and shape of aliphatic carboxylic acid silver salt particles]
The shape of the aliphatic carboxylic acid silver salt particles according to the present invention is not particularly limited, and may be any of needle shape, rod shape, flat plate shape, and flake shape. In the present invention, flake-shaped aliphatic carboxylic acid silver salts and short needle-shaped or rectangular parallelepiped-shaped aliphatic carboxylic acid silver salts having a major axis / minor axis length ratio of 5 or less are preferably used.

  The flake shaped aliphatic carboxylic acid silver salt is defined as follows. The aliphatic carboxylate silver salt was observed with an electron microscope, the shape of the aliphatic carboxylate silver salt particle was approximated to a rectangular parallelepiped, and the sides of this rectangular parallelepiped were designated as a, b, and c from the shortest side (c is b The calculation may be performed with the shorter numerical values a and b, and x is obtained as follows.

x = b / a
In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 20 ≧ x (average) ≧ 2.0. Incidentally, the needle shape is 1 ≦ x (average) <1.5.

  In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.23 μm, more preferably 0.1 μm or more and 0.20 μm or less. The average c / b is preferably 1 or more and 6 or less, more preferably 1.05 or more and 4 or less, still more preferably 1.1 or more and 3 or less, and particularly preferably 1.1 or more and 2 or less.

  The aliphatic carboxylic acid silver salt according to the present invention may be a crystal particle having a core / shell structure as disclosed in European Patent 1168069A1 and Japanese Patent Application Laid-Open No. 2002-23303. In the case of a core / shell structure, all or a part of either the core part or the shell part is made of an organic acid silver salt other than silver aliphatic carboxylate, for example, an organic compound such as phthalic acid or benzimidazole. A silver salt may be used as a constituent of the crystal grains.

  In the aliphatic carboxylic acid silver salt according to the present invention, the average equivalent circle diameter is preferably 0.05 μm or more and 0.8 μm or less, and the average thickness is 0.005 μm or more and 0.07 μm or less. The average equivalent circle diameter is preferably 0.2 μm or more and 0.5 μm or less, and the average thickness is 0.01 μm or more and 0.05 μm or less.

  When the average equivalent circle diameter is 0.05 μm or less, the transparency is excellent, but the image storage stability is poor, and when the average particle diameter is 0.8 μm or more, devitrification is severe. When the average thickness is 0.005 μm or less, the surface area is large, and silver ions are rapidly supplied during development. In particular, the low density area is not used for silver images, and there is a large amount of silver ions remaining in the film. The image storage stability is significantly deteriorated. On the other hand, when the average thickness is 0.07 μm or more, the surface area is reduced and the image stability is improved. However, the silver supply during development is slow, and the developed silver shape is uneven particularly in the high density portion, resulting in the highest result. Concentration tends to be low.

  The particle size distribution of the organic acid silver salt particles according to the present invention (for example, the particle size distribution determined as the equivalent circle diameter) is preferably monodisperse. The monodispersion mentioned here means that the coefficient of variation of the particle diameter obtained by the following formula is 25% or less. Preferably it is 20% or less, More preferably, it is 15% or less.

Coefficient of variation of particle size% = (standard deviation of particle size / average value of particle size) × 100
In order to obtain the average equivalent circle diameter, the dispersed aliphatic carboxylic acid silver salt is diluted and dispersed on a grid with a carbon support film, and a transmission electron microscope (for example, JEOL Ltd., 2000FX type) is directly used. Images can be taken at a magnification of 5000 times, the negative is captured as a digital image by a scanner, and 300 or more particle sizes (equivalent circle diameter) are measured using an appropriate image processing software to calculate the average particle size. .

  The average thickness can be calculated by a method using a TEM (transmission electron microscope) as shown below.

  First, the photosensitive layer coated on the support is attached to an appropriate holder with an adhesive, and an ultrathin slice having a thickness of 0.1 to 0.2 μm is produced using a diamond knife in a direction perpendicular to the support surface. To do. The prepared ultra-thin slice is supported on a copper mesh, transferred onto a carbon film that has been hydrophilized by glow discharge, and cooled with liquid nitrogen to −130 ° C. or lower using a transmission electron microscope (hereinafter referred to as TEM). The bright field image is observed at a magnification of 5,000 to 40,000, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like. At this time, it is preferable to appropriately select a portion where the section is not torn or slack as the field of view to be observed.

  As the carbon film, it is preferable to use a film supported by an organic film such as an extremely thin collodion or form bar, and more preferably, it is formed on a rock salt substrate and obtained by dissolving and removing the substrate. It is a carbon-only film obtained by removal by organic solvent and ion etching. The acceleration voltage of TEM is preferably 80 to 400 kV, particularly preferably 80 to 200 kV.

  In addition, for details of electron microscope observation techniques and sample preparation techniques, see “The Japan Electron Microscopy Society Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Japan Electron Microscopy Society Kanto Branch / Electron Microscope Biological Samples” "Manufacturing method" (Maruzen) can be referred to respectively.

  A TEM image recorded on a suitable medium is preferably decomposed into at least 1024 pixels × 1024 pixels, preferably 2048 pixels × 2048 pixels or more, and image processing by a computer is performed. In order to perform image processing, it is preferable that an analog image recorded on a film is converted into a digital image by a scanner or the like, and shading correction, contrast / edge enhancement, and the like are performed as necessary. Thereafter, a histogram is prepared, and a portion corresponding to the aliphatic carboxylate silver is extracted by binarization processing.

  The thickness of the extracted aliphatic carboxylic acid silver salt particles is manually measured with an appropriate software of 300 or more, and an average value is obtained.

  The method for obtaining the aliphatic carboxylic acid silver salt particles having flake shaped particles is not particularly limited, for example, a mixed state when forming an organic acid alkali metal salt soap, or a mixed state when adding silver nitrate to the soap. It is effective to keep the ratio in good condition, and to optimally set the ratio of the organic acid to the soap and the ratio of the silver nitrate that reacts with the soap.

  Further, the aliphatic carboxylic acid silver salt particles having a tabular shape (the average equivalent circle diameter is 0.05 μm or more and 0.8 μm or less, and the average thickness is 0.005 μm or more, The aliphatic carboxylic acid silver salt particles having a particle size of 0.07 μm or less are preferably preliminarily dispersed together with a binder or a surfactant as necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. As the preliminary dispersion method, for example, a general stirrer such as an anchor type or a propeller type, a high speed rotating centrifugal radiation type stirrer (dissolver), or a high speed rotating shear type stirrer (homomixer) can be used.

  As the media disperser, for example, a rolling mill such as a ball mill, a planetary ball mill, and a vibration ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills can be used. As a high-pressure homogenizer, Various types can be used, such as a type that collides with walls, plugs, etc., a type in which liquids are divided into a plurality of parts and then collided with each other at high speed, and a type through which fine orifices are passed.

  Ceramics used for the ceramic beads used when dispersing media include yttrium-stabilized zirconia and zirconia-reinforced alumina (ceramics containing these zirconia) because of the low generation of impurities due to friction with the beads and the dispersing machine during dispersion. Is abbreviated as zirconia in the following).

  In the apparatus used when dispersing the flat aliphatic carboxylic acid silver salt particles, the material of the member in contact with the aliphatic carboxylic acid silver salt particles is, for example, ceramics such as zirconia, alumina, silicon nitride, and boron nitride. It is preferable to use a metal or diamond, and it is particularly preferable to use zirconia. When the above dispersion is performed, the binder concentration is preferably added in an amount of 0.1 to 10% of the mass of the aliphatic silver carboxylate, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion through the main dispersion. As preferable operating conditions for this dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, it is preferable that the operating conditions are 29 to 100 MPa and the number of operations is 2 or more. Moreover, when using a media disperser as a dispersion | distribution means, a peripheral speed of 6-13 m / sec is mentioned as preferable conditions.

  In the present invention, the organic acid silver salt particles are preferably formed in the presence of a compound that functions as a crystal growth inhibitor or a dispersant. Moreover, it is preferable that the compound which functions as a crystal growth inhibitor or a dispersing agent is an organic compound having a hydroxyl group or a carboxyl group.

  The compound functioning as a crystal growth inhibitor or dispersant is smaller in the production process of organic acid silver particles than when it is produced under the condition where the organic acid silver is produced under the condition where the compound is not present. A compound having the function and effect of particle size reduction and monodispersion. Specific examples include monohydric alcohols having 10 or less carbon atoms, preferably secondary alcohols, tertiary alcohols, glycols such as ethylene glycol and propylene glycol, polyethers such as polyethylene glycol, and glycerin. A preferable addition amount is 10 to 200% by mass with respect to the aliphatic carboxylate silver.

  On the other hand, branched aliphatic carboxylic acids containing isomers such as isoheptanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, isopalmitic acid, isostearic acid, isoarachidic acid, isobehenic acid and isohexaconic acid are also preferred. In this case, a preferable side chain includes an alkyl group or alkenyl group having 4 or less carbon atoms. Also, aliphatic unsaturated carboxylic acids such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, morotic acid, eicosenoic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, ceracolonic acid It is done. A preferable addition amount is 0.5 to 10 mol% of the organic acid silver.

  Glycosides such as glucoside, galactoside and fructoside, trehalose type disaccharides such as trehalose and sucrose, polysaccharides such as glycogen, dextrin, dextran and alginic acid, cellosolves such as methyl cellosolve and ethyl cellosolve, sorbitan, sorbit, ethyl acetate and acetic acid Water-soluble organic solvents such as methyl and dimethylformamide, water-soluble polymers such as polyvinyl alcohol, polyacrylic acid, acrylic acid copolymer, maleic acid copolymer, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone and gelatin Are also preferred compounds. A preferable addition amount is 0.1 to 20% by mass with respect to the aliphatic carboxylate silver.

  Alcohols having 10 or less carbon atoms, preferably secondary alcohols such as isopropyl alcohol and tertiary alcohols such as t-butyl alcohol are used to increase the solubility of the alkali metal salt of aliphatic carboxylic acid in the particle production process. By reducing the viscosity and increasing the stirring efficiency, it is monodispersed and the particle size is reduced. Branched aliphatic carboxylic acids and aliphatic unsaturated carboxylic acids have higher steric hindrance than the main component linear aliphatic carboxylic acid silver when crystallization of the aliphatic carboxylic acid silver, and the disorder of the crystal lattice is large. Therefore, large crystals are not generated, and as a result, the particle size is reduced. Hereinafter, the materials constituting each layer of the dry imaging material shown in FIG. 3 will be described.

(Photosensitive silver halide grains)
The photosensitive silver halide grains according to the present invention (simply also referred to as “silver halide grains” or “silver halide”) can inherently absorb light as an inherent property of silver halide crystals. Or visible light or infrared light can be absorbed by an artificial physicochemical method, and when light in any region within the light wavelength range from the ultraviolet light region to the infrared light region is absorbed, Silver halide crystal grains that have been processed and produced so that physicochemical changes can occur in the silver halide crystals or on the crystal surface.

  As the photosensitive silver halide grains according to the present invention, silver halide grains disclosed in many patent publications and the like related to silver salt photothermographic dry imaging materials can be used. Specific examples of silver halide grains that can be preferably used are described, for example, in JP-A Nos. 11-212193, 11-338085, 2000-29155, and 2003-270755. Silver halide grains produced according to the production method, chemical properties such as halogen composition, physical properties such as shape, and the like.

  The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. Particularly preferred is silver halide or silver iodide.

  In the silver halide grains used in the present invention, it is preferable to appropriately reduce the grain size of the silver halide grains in order to prevent white turbidity after image formation and to obtain good image quality, and the average grain size is 0. As a value when particles less than 0.02 μm are excluded from measurement, it is preferably 0.030 μm or more and 0.055 μm or less.

  Examples of the shape of the silver halide grains include cubes, octahedrons, tetrahedron grains, tabular grains, spherical grains, rod-like grains, potato-like grains, etc. Among these, in particular, cubes, octahedrons, 14 Planar and tabular silver halide grains are preferred.

  The photosensitive silver halide grain according to the present invention is 0.001 to 0.7 mol, preferably 0.03 to 0.5 mol, based on 1 mol of an aliphatic carboxylic acid silver salt that can function as a silver ion source. It is preferred to use.

[Heat conversion internal latent image type silver halide grains]
The photosensitive silver halide grain according to the present invention is a heat conversion internal latent image type (internal latent image type after heat development) halogen disclosed in Japanese Patent Application Laid-Open No. 2003-270755 and Japanese Patent Application No. 2003-337269. Silver halide grains, that is, silver halide grains whose surface sensitivity is lowered by conversion from a surface latent image type to an internal latent image type by heat development are preferred. In other words, in exposure before heat development, a latent image that can function as a catalyst for a development reaction (reduction reaction of silver ions by a silver ion reducing agent) is formed on the surface of the silver halide grains, In exposure, since many latent images are formed inside the surface of the silver halide grains, it is a silver halide grain in which latent image formation on the surface is suppressed. preferable.

  The heat-converted internal latent image type silver halide grain according to the present invention is, in the same manner as a normal surface latent image type silver halide grain, 0. 1 mol per mol of an aliphatic carboxylic acid silver salt that can function as a silver ion source. It is preferably used at 001 to 0.7 mol, preferably 0.03 to 0.5 mol.

[Silver halide grain dispersion technology]
In the production process of the silver salt photothermographic imaging material of the present invention, from the viewpoint of improving photographic performance and color tone, aggregation of silver halide grains is prevented, and silver halide grains are dispersed relatively uniformly. In particular, it is preferable that the developed silver can be controlled to a desired shape.

  In order to prevent the above-described aggregation, uniform dispersion, etc., the gelatin used in the present invention has modified the properties of the gelatin by chemically modifying the hydrophilic groups such as amino groups and carboxyl groups of the gelatin according to the conditions of use. Those are preferred.

  For example, examples of the hydrophobic modification of the amino group in the gelatin molecule include phenylcarbamoylation, phthalation, succination, acetylation, benzoylation, and nitrophenylation, but are not particularly limited thereto. The substitution rate is preferably 95% or more, more preferably 99% or more. Moreover, the hydrophobic modification of the carboxyl group may be combined, and examples thereof include methyl esterification and amidation, but are not particularly limited thereto. The substitution rate of the carboxyl group is preferably 50 to 90%, more preferably 70 to 90%. Here, the hydrophobic group in the above-mentioned hydrophobization modification refers to a group whose hydrophobicity is increased by substituting the amino group and / or carboxyl group of gelatin.

  Further, the silver halide grain emulsion according to the present invention is preferably prepared by using a polymer that dissolves in both water and an organic solvent as described below in place of gelatin or in combination with gelatin. . For example, it is particularly preferred when the silver halide grain emulsion is uniformly dispersed in an organic solvent system.

  Examples of the organic solvent include alcohol-based, ester-based, and ketone-based compounds. In particular, ketone organic solvents such as acetone, methyl ethyl ketone, and diethyl ketone are preferable.

  The polymer that is soluble in both water and organic solvent may be any of natural polymers, synthetic polymers, and copolymers. For example, gelatins, rubbers, and the like that have been modified so as to belong to the category of the present invention can be used. Alternatively, polymers belonging to the following classifications can be used by introducing functional groups suitable for the purpose of preventing aggregation and uniform dispersion.

  For example, the polymers according to the present invention include poly (vinyl alcohol) s, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, poly (vinyl pyrrolidone) s, casein, starch, poly (acrylic acid and acrylic acid Esters), poly (methyl methacrylic acid and methacrylic acid esters), poly (vinyl chloride) s, poly (methacrylic acid) s, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene- Butadiene copolymers, poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (vinylidene chloride) s, Poly (epoxides), poly (carbonate) G) s, poly (vinyl acetate), poly (olefins), cellulose esters, poly (amides), and the like.

  Several kinds of these polymers may be copolymers, but polymers obtained by copolymerizing monomers of acrylic acid, methacrylic acid and esters thereof are particularly preferable.

  The polymer according to the present invention may be a polymer that dissolves in both water and an organic solvent in the same state, but also includes those that can be dissolved or insolubilized in water or an organic solvent by controlling the pH or controlling the temperature. It is.

  For example, although a polymer having an acidic group such as a carboxyl group becomes hydrophilic in a dissociated state depending on the type, it becomes oleophilic and soluble in a solvent when the pH is lowered to a non-dissociated state. Conversely, a polymer having an amino group becomes lipophilic when the pH is raised, and becomes ionized and water-soluble when the pH is lowered.

  Nonionic activators are well known for the phenomenon of cloud point, but they have a property that they become lipophilic and soluble in organic solvents when the temperature rises, and are hydrophilic, ie, soluble in water when the temperature is lowered. Is also included in the polymer. What is necessary is just to form a micelle and to emulsify uniformly even if it does not melt | dissolve completely.

  In the present invention, since various monomers are combined, it is generally not stated which monomer should be used and how much, but it is desirable to combine a hydrophilic monomer and a hydrophobic monomer in an appropriate ratio. It can be easily understood that the polymer is obtained.

  The polymer that dissolves in both the water and the organic solvent may have a solubility of at least 1% by mass (25 ° C.) with respect to water, although it may be adjusted by dissolving the pH and other conditions as described above, or may not be adjusted. The organic solvent preferably has a solubility of 5% by mass or more (25 ° C.) in methyl ethyl ketone.

  As the polymer that is soluble in both the water and the organic solvent according to the present invention, a so-called block polymer, graft polymer, comb polymer, and the like are more suitable than a linear polymer from the viewpoint of solubility. A comb type polymer is particularly preferable. The isoelectric point of the polymer is preferably pH 6 or less.

  In the production process of the dry imaging material of the present invention, a surfactant, particularly a nonionic surfactant, is added to the silver halide grain dispersion for the purpose of preventing aggregation and uniform dispersion of the silver halide grains. It is also preferable to contain.

  For nonionic surfactants, see generally Griffin W. et al. C. [J. Soc. Cosm. Chem. , 1, 311 (1949)], the hydrophilic / lipophilic equilibrium defined by its “HLB” value reflecting the proportion of hydrophilic and lipophilic groups in the molecule is −18 to 18, preferably − It is selected from nonionic hydrophilic compounds that are 15-0.

  As the nonionic surfactant used in the photosensitive silver halide emulsion according to the present invention, an activator represented by the following general formula (NSA1) or general formula (NSA2) is preferable.

Formula (NSA1) HO- (EO) _a- (AO) _b- (EO) _c -H
General formula (NSA2) HO- (AO) _d- (EO) _e- (AO) _f- H
In the formula, EO represents an oxyethylene group, AO represents an oxyalkylene group having 3 or more carbon atoms, and a, b, c, d, e, and f represent 1 or more numbers.

  Both are called pluronic-type nonionic surfactants, and in the general formula (NSA1) or (NSA2), examples of the oxyalkylene group having 3 or more carbon atoms represented by AO include oxypropylene group, oxybutylene group, oxy Long chain alkylene groups and the like can be mentioned, and oxypropylene groups are most preferred.

  A, b and c each represent a number of 1 or more, and d, e and f each represent a number of 1 or more. a and c are each preferably 1 to 200, more preferably 10 to 100, and b is preferably 1 to 300, and more preferably 10 to 200. d and f are each preferably 1 to 100, more preferably 5 to 50, respectively, and e is preferably 1 to 100, more preferably 2 to 50.

  In the photosensitive silver halide emulsion of the present invention, a macrocyclic compound containing a hetero atom is used. The macrocyclic compound containing a heteroatom is a 9-membered or higher macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a selenium atom as a heteroatom. Furthermore, a 12-24 membered ring is preferable, and a 15-21 membered ring is still more preferable.

  Representative compounds are those known as crown ethers, these compounds are C.I. J. et al. Pederson, Journal of American Chemical Society Vol, 86 (2495), 7017-7036 (1967), G.P. W. Gokel, S.M. H, Korzenowski, “Macrocyclic polyethr synthesis”, Springer-Vergal, (1982), Oda, Shono, Tabushi, “Chemistry of Crown Ether”, Chemistry Dojin (1978), Tafushi, “Host-Guest” Kyoritsu Shuppan (1979), Sasaki Koga "Synthetic Organic Chemistry" Vol 45 (6), 571-582 (1987).

(Chemical sensitization)
The photosensitive silver halide grains according to the present invention can be subjected to chemical sensitization disclosed in many patent publications relating to dry imaging materials. For example, by a method described in JP-A-2003-270755, JP-A-2001-249428, and JP-A-2001-249426, a compound that releases chalcogen such as sulfur, selenium, tellurium, gold ions, etc. Chemical sensitization centers (chemical) that can capture electrons or holes generated by photoexcitation of photosensitive silver halide grains or spectral sensitizing dyes on the grains by using noble metal compounds that release noble metal ions. Sensitizing nuclei) can be formed and imparted. In particular, it is preferably chemically sensitized with an organic sensitizer containing a chalcogen atom.

  These organic sensitizers containing chalcogen atoms are preferably compounds having groups capable of adsorbing to silver halide and unstable chalcogen atom sites.

  As these organic sensitizers, JP-A-60-150046, JP-A-4-109240, JP-A-11-218874, JP-A-11-218875, JP-A-11-218876, JP-A-11-194447, etc. The disclosed organic sensitizers having various structures can be used. Among them, at least one compound having a structure in which a chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond is used. Preferably there is. In particular, a thiourea derivative having a heterocyclic group and a triphenylphosphine sulfide derivative are preferred.

  When the surface of the photosensitive silver halide grain according to the present invention is chemically sensitized, it is preferable that the chemical sensitization effect substantially disappears after the thermal development process. Here, the chemical sensitization effect substantially disappears when the sensitivity of the imaging material obtained by the chemical sensitization technique is 1.1 when the chemical sensitization is not performed after the thermal development process. Say to decrease to less than double. In order to eliminate the chemical sensitization effect in the thermal development process, an oxidant capable of destroying the chemical sensitization center (chemical sensitization nucleus) by an oxidation reaction at the time of thermal development, for example, the above-mentioned halogen radical releasing compound, etc. It is necessary to contain an appropriate amount of the above in the emulsion layer and / or the non-photosensitive layer of the imaging material. The content of the oxidizing agent is preferably adjusted in consideration of the oxidizing power of the oxidizing agent, the reduction range of the chemical sensitization effect, and the like.

(Spectral sensitization)
The photosensitive silver halide grain according to the present invention is preferably subjected to spectral sensitization by adsorbing a spectral sensitizing dye. Regarding spectral sensitization techniques, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, and hemicyanines disclosed in many patent publications related to silver salt photothermographic dry imaging materials. A technique using a dye, an oxonol dye, a hemioxonol dye, or the like as a spectral sensitizing dye can be used.

  Specific examples of spectral sensitization techniques that can be preferably used in the dry imaging material of the present invention include, for example, general formula (1) and general formula (2) described in JP-A No. 2004-309758. This is a technique based on a spectral sensitization technique in which at least one selected from the sensitizing dyes shown is used.

  The emulsion containing photosensitive silver halide grains and aliphatic carboxylic acid silver salt grains used in the dry imaging material of the present invention substantially contains a dye having no spectral sensitizing action or visible light itself together with a sensitizing dye. The emulsion may contain a substance that does not absorb light and exhibits a supersensitization effect in the emulsion, whereby the silver halide grains may be supersensitized.

  Useful sensitizing dyes, combinations of dyes exhibiting supersensitization, and substances exhibiting supersensitization are described in RD17643 (issued in December, 1978), page 23, Section J, or Japanese Patent Publication No. 9-25500, 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. As supersensitizers, heteroaromatic mercapto compounds or mercapto derivatives are described. Compounds are preferred.

  In addition to the above supersensitizers, macrocycles having heteroatoms disclosed in JP-A-2001-330918 can also be used as supersensitizers.

  It is preferable that the surface of the photosensitive silver halide grain according to the present invention is spectrally sensitized by adsorbing a spectral sensitizing dye, and the spectral sensitization effect substantially disappears after the thermal development process. . Here, the spectral sensitization effect substantially disappears when the sensitivity of the imaging material obtained with a sensitizing dye, supersensitizer, etc. is the sensitivity when the spectral sensitization is not performed after the thermal development process. It means to decrease to 1.1 times or less.

  In order to eliminate the spectral sensitization effect in the thermal development process, a spectral sensitizing dye that is easily detached from the silver halide grains by heat is used during thermal development or / and the spectral sensitizing dye is destroyed by an oxidation reaction. It is necessary to contain an appropriate amount of an oxidizing agent that can be formed, for example, the above-mentioned halogen radical releasing compound in the emulsion layer and / or the non-photosensitive layer of the imaging material. The content of the oxidizing agent is preferably adjusted in consideration of the oxidizing power of the oxidizing agent, the reduction range of the spectral sensitization effect, and the like.

(Silver ion reducing agent)
The reducing agent according to the present invention can reduce silver ions in the photosensitive layer, and is also referred to as a developer. Examples of the reducing agent include compounds represented by the following general formula (RD1).

  In the present invention, as the silver ion reducing agent, in particular, a compound in which at least one of the reducing agents is represented by the following general formula (RD1) is used alone or in combination with a reducing agent having another different chemical structure. preferable.

[Wherein, X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ₂ represents an alkyl group and may be the same or different. R ₃ represents a hydrogen atom or a group that can be substituted on a benzene ring. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
Among the compounds represented by the general formula (RD1), a highly active reducing agent (hereinafter referred to as a compound of (RD1a)) in which at least one of R ₂ is a secondary or tertiary alkyl group is used. The photothermographic material having a high density and excellent light-storing image storage stability can be obtained, which is more preferable. In the present invention, it is preferable to use a compound of (RD1a) and a compound of the following general formula (RD2) in order to obtain a desirable color tone.

[Wherein, X ₂ represents a chalcogen atom or CHR ₅ , and R ₅ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ₆ represents an alkyl group, which may be the same or different, but is not a secondary or tertiary alkyl group. R ₇ represents a hydrogen atom or a group that can be substituted on a benzene ring. R ₈ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
As the combined ratio, [the mass of the compound of (RD1a)]: [the mass of the compound of general formula (RD2)] is preferably 5:95 to 45:55, more preferably 10:90 to 40: 60.

(Image tone)
Next, the color tone of an image obtained by thermally developing a silver salt photothermographic dry imaging material will be described.

  Regarding the color tone of an output image for medical diagnosis like a conventional X-ray photographic film, it is said that a cold tone image tone is easier for a reader to obtain a more accurate diagnosis observation result. Here, the image tone that is cold refers to a pure black tone or a bluish black tone of a black image. On the other hand, the warm image tone is said to be a warm black tone in which the black image is tinged with brown. However, in order to allow a more precise quantitative discussion, the International Lighting Commission (CIE) ), Based on the recommended expression.

The terms “more cold” and “more warm” regarding the color tone can be expressed by the hue angle hab at the minimum density Dmin and the optical density D = 1.0. That is, the hue angle hab is expressed by the color coordinates a ^* and b ^* of the color space L ^* a ^* b ^* color space, which is a color space having a perceptually uniform rate recommended by the International Commission on Illumination (CIE) in 1976. Using the following formula.

hab = tan ⁻¹ (b ^* / a ^* )
As a result of examination by the expression method based on the hue angle, the hue of the photothermographic dry imaging material of the present invention after development is preferably such that the range of the hue angle hab is 180 degrees <hab <270 degrees, more preferably 200 degrees. It has been found that degrees <hab <270 degrees, most preferably 220 degrees <hab <260 degrees. This is disclosed in Japanese Patent Laid-Open No. 2002-6463.

Conventionally, the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space near the optical density of 1.0 is specified as u ^* , v ^* or a ^* , b ^* . It is known that a diagnostic image with a favorable color tone can be obtained by adjusting to a numerical value, and is described in, for example, Japanese Patent Application Laid-Open No. 2000-29164.

However, as disclosed in Japanese Patent Application Laid-Open No. 2004-94240, the silver salt photothermographic dry imaging material of the present invention has a CIE 1976 (L ^* u ^* v ^* ) color space or (L ^* a ^* b ^*). ) In a color space, plotting u ^* , v ^* or a ^* , b ^* at various photographic densities on a graph with the horizontal axis u ^* or a ^* and the vertical axis v ^* or b ^*, and linear regression It has been found that, when a straight line is created, by adjusting the linear regression line to a specific range, it is possible to have a diagnostic property equal to or higher than that of a conventional wet silver salt photosensitive material. Preferred specific condition ranges are described below.

(1) The silver salt photothermographic dry imaging material was measured for each of the optical densities of 0.5, 1.0, 1.5 and the lowest optical density of the silver image obtained after the heat development processing, and CIE 1976 (L ^* u ^* v ^* ) The coefficient of determination of the linear regression line created by arranging u ^* and v ^* at the above optical densities in two-dimensional coordinates where the horizontal axis of the color space is u ^* and the vertical axis is v ^*. Determination) R ² is preferably 0.998 to 1.000. Furthermore, it is preferable that the v ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (v ^* / u ^* ) is 0.7 to 2.5.

(2) In addition, the optical density of the photothermographic dry imaging material is measured at 0.5, 1.0, 1.5 and the lowest optical density, next to the CIE 1976 (L ^* a ^* b ^* ) color space. The coefficient of determination (multiple determination) R ^{2 of} the linear regression line created by arranging a ^* and b ^* at each optical density in the two-dimensional coordinates where the axis is a ^* and the vertical axis is b ^* is from 0.998 to It is preferable that it is 1.000. Furthermore, it is preferable that the b ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (b ^* / a ^* ) is 0.7 to 2.5.

Then, the linear regression line creation methods described above, namely u ^* in CIE1976 color space, v ^* and a ^*, illustrating an example of a b ^* measurement methods.

A four-stage wedge sample including an unexposed portion and optical densities of 0.5, 1.0, and 1.5 is prepared using a heat development apparatus. Each wedge density part produced in this way is measured with a spectrocolorimeter (Minolta Co., Ltd .: CM-3600d, etc.), and u ^* , v ^* or a ^* , b ^* are calculated. The measurement conditions at that time are F7 light source as the light source, the viewing angle is 10 degrees, and the measurement is performed in the transmission measurement mode. Plot u ^* , v ^* or a ^* , b ^* measured on a graph with u ^* or a ^{* on} the horizontal axis and v ^* or b ^{* on the} vertical axis to obtain a linear regression line, and the coefficient of determination (multiple determination) Find R ² , intercept and slope.

  Next, a specific method for obtaining a linear regression line having the above features will be described.

  In the present invention, adjustment of the addition amount of a compound or the like directly or indirectly involved in the development reaction process of a reducing agent (developer), silver halide grains, aliphatic silver carboxylate and the following toning agent, etc. Thus, the developed silver shape can be optimized to obtain a preferable color tone. For example, when the developed silver shape is dendritic, it becomes a bluish direction, and when it is a filament shape, it becomes a yellowish direction. That is, it can be adjusted in consideration of the tendency of the developed silver shape.

  Conventionally, phthalazinone or phthalazine and phthalic acids and phthalic anhydrides are generally used as toning agents. Examples of suitable toning agents include RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, and 4,021,249. Is disclosed.

  In addition to such a toning agent, a color tone using a coupler disclosed in JP-A No. 11-288057, European Patent No. 1,134,611A2, etc. and a leuco dye described in detail below. Can also be adjusted. In particular, a coupler or leuco dye is preferably used for fine adjustment of the color tone.

(Leuco dye)
As described above, the dry imaging material of the present invention can also be adjusted in color tone using a leuco dye. The leuco dye is preferably any colorless or slightly colored compound that is oxidized to a colored form when heated at a temperature of about 80-200 ° C. for about 0.5-30 seconds. Any leuco dye that can be oxidized by the body to form a pigment can be used. Compounds that are pH sensitive and can be oxidized to a colored state are useful.

  Representative leuco dyes suitable for use in the present invention are not particularly limited. For example, biphenol leuco dyes, phenol leuco dyes, indoaniline leuco dyes, acrylated azine leuco dyes, phenoxazine leuco dyes, phenodiazine leuco dyes. And phenothiazine leuco dye. Also useful are US Pat. Nos. 3,445,234, 3,846,136, 3,994,732, 4,021,249, 4,021,250, 4,022,617, 4,123,282, 4,368,247, 4,461,681, and JP-A-50-36110, 59-26831, These are leuco dyes disclosed in JP-A-5-204087, JP-A-11-231460, JP-A-2002-169249, and JP-A-2002-236334.

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination of a plurality of types. In the present invention, when a highly active reducing agent is used, the color tone (especially yellowishness) changes depending on the amount and ratio of use, or by using fine grain silver halide, the concentration is particularly 2.0. In order to prevent the image from becoming excessively reddish in the above high density portion, it is preferable to use a leuco dye that develops yellow and cyan colors and adjust the amount of use.

  The color density is preferably adjusted appropriately in relation to the color tone of the developed silver itself. In the present invention, the color tone is adjusted so as to have an image in the above preferred color tone range by developing the color so as to have a reflection optical density of 0.01 to 0.05 or a transmission optical density of 0.005 to 0.50. preferable. In the present invention, the sum of the maximum densities at the maximum absorption wavelength of the dye image formed by the leuco dye is preferably 0.01 or more and 0.50 or less, more preferably 0.02 or more and 0.30 or less, and particularly preferably It is preferable to develop the color so as to have 0.03 or more and 0.10 or less.

(binder)
In the dry imaging material of the present invention, the photosensitive layer and the non-photosensitive layer according to the present invention can contain a binder for various purposes. The binder contained in the photosensitive layer according to the present invention is capable of supporting organic silver salts, silver halide grains, reducing agents, and other components, and suitable binders are transparent or translucent and generally colorless. A natural polymer, a synthetic polymer, a copolymer, and other media for forming a film, for example, those described in paragraph “0069” of JP-A No. 2001-330918.

  Of these, particularly preferred examples include methacrylic acid alkyl esters, methacrylic acid aryl esters, and styrenes. Among such polymer compounds, a polymer compound having an acetal group is preferably used. Even a high molecular compound having an acetal group is more preferably a polyvinyl acetal having an acetoacetal structure, for example, U.S. Pat. Nos. 2,358,836, 3,003,879, 2,828,204, UK The polyvinyl acetal shown by patent 771,155 etc. can be mentioned. As the polymer compound having an acetal group, a compound represented by the general formula (V) described in “150” of JP-A No. 2002-287299 is particularly preferable.

  Preferred binders for the photosensitive layer according to the present invention are polyvinyl acetals, particularly preferably polyvinyl butyral, which is preferably used as the main binder. The main binder mentioned here means “a state in which the polymer occupies 50% by mass or more of the total binder of the photosensitive layer”. Therefore, other polymers may be blended and used within a range of less than 50% by weight of the total binder. These polymers are not particularly limited as long as the polymer of the present invention is soluble. More preferably, a polyvinyl acetate, a polyacryl resin, a urethane resin, etc. are mentioned.

  The glass transition temperature (Tg) of the binder used in the present invention is preferably 70 to 105 ° C. in that a sufficient maximum density can be obtained in image formation.

  The binder of the present invention has a number average molecular weight of 1,000 to 1,000,000, preferably 10,000 to 500,000, and a degree of polymerization of about 50 to 1,000.

  In addition, for non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters which are polymers having a higher softening temperature, particularly polymers such as triacetyl cellulose and cellulose acetate butyrate. Is preferred. If necessary, two or more binders can be used in combination as described above.

Such a binder is used in an effective range to function as a binder. The effective range can be easily determined by one skilled in the art. For example, as an index for holding at least the organic silver salt in the photosensitive layer (image forming layer), the ratio of the binder to the organic silver salt is preferably 15: 1 to 1: 2 (mass ratio), and particularly 8: A range of 1-1: 1 is preferred. That is, it is preferable that the binder amount of the photosensitive layer is a 1.5~6g / m ^2, more preferably from 1.7~5g / m ^2. If it is less than 1.5 g / m ² , the density of the unexposed area is significantly increased, and may not be used.

  An organic gelling agent may be contained in the photosensitive layer. The organic gelling agent referred to here has a function of giving a yield value to the system by adding it to an organic liquid, such as polyhydric alcohols, and eliminating or reducing the fluidity of the system. The compound which has.

  It is also a preferred embodiment that the photosensitive layer coating solution contains an aqueous dispersed polymer latex. In this case, a polymer latex in which 50% by mass or more of the total binder in the coating solution for the photosensitive layer is dispersed in water is preferable. Further, when a polymer latex is used in the preparation of the photosensitive layer, 50% by mass or more of the total binder in the photosensitive layer is preferably a polymer latex-derived polymer, and more preferably 70% by mass or more.

(Crosslinking agent)
The photosensitive layer according to the present invention can contain a cross-linking agent capable of connecting the binders according to the present invention by cross-linking. It is known that the use of a crosslinking agent for the above binder improves filming and reduces development unevenness, but also has the effect of suppressing fog during storage and suppressing the generation of printout silver after development. is there.

  Examples of the crosslinking agent to be used include various crosslinking agents conventionally used for photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based, sulfone described in JP-A-50-96216. Acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents are used, and the following isocyanate-based, silane compound-based, epoxy-based compounds, and acid anhydrides are preferable.

  Isocyanate-based crosslinking agents are isocyanates having at least two isocyanate groups and adducts thereof (adducts). More specifically, aliphatic diisocyanates, aliphatic diisocyanates having a cyclic group, benzene Diisocyanates, naphthalene diisocyanates, biphenyl isocyanates, diphenylmethane diisocyanates, triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates and divalent or trivalent polyalcohols with these isocyanates Adducts and the like. As specific examples, isocyanate compounds described on pages 10 to 12 of JP-A-56-5535 can be used.

  The adduct of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion and prevent layer peeling, image shift, and bubble generation. The isocyanate involved may be added to any part of the photothermographic material. For example, in the support (especially when the support is paper, it can be included in the size composition) photosensitive layer, support layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer on the side, and can be added to one or more of these layers. As the thioisocyanate-based crosslinking agent that can be used in the present invention, compounds having a thioisocyanate structure corresponding to the above-mentioned isocyanates are also useful. The amount of the crosslinking agent used is usually in the range of 0.001 to 2 mol, preferably 0.005 to 0.5 mol, with respect to 1 mol of silver.

  The isocyanate compound and thioisocyanate compound that can be contained in the present invention are preferably compounds that function as the above-mentioned crosslinking agent, but a result may be obtained that may be a compound having only one functional group.

  Examples of the silane compound include compounds represented by general formulas (1) to (3) disclosed in JP-A No. 2001-264930.

  Moreover, as an epoxy compound which can be used as a crosslinking agent, what is necessary is just to have one or more epoxy groups, and there is no restriction | limiting in the number of epoxy groups, molecular weight, and others. The epoxy group is preferably contained in the molecule as a glycidyl group via an ether bond or an imino bond. The epoxy compound may be any of a monomer, an oligomer, a polymer, etc., and the number of epoxy groups present in the molecule is usually about 1 to 10, preferably 2 to 4. When the epoxy compound is a polymer, it may be either a homopolymer or a copolymer, and the number average molecular weight Mn is particularly preferably in the range of about 2,000 to 20,000.

  The acid anhydride used in the present invention is a compound having at least one acid anhydride group represented by the following structural formula. The number of acid anhydride groups, molecular weight, and the like are not particularly limited as long as they have one or more acid anhydride groups.

-CO-O-CO-
Said epoxy compound and acid anhydride may use only 1 type, or may use 2 or more types together. The addition amount is not particularly limited, but is preferably in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol / m ² , more preferably in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol / m ² . It is. This epoxy compound or acid anhydride can be added to any layer on the photosensitive layer side of the support, such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. It can be added to one layer or two or more layers.

(Silver saving agent)
The photosensitive layer or the non-photosensitive layer according to the present invention may contain a silver saving agent. The silver saving agent as used herein refers to a compound that can reduce the amount of silver necessary to obtain a certain silver image density.

  Although various mechanisms for the function of reducing the required silver amount are conceivable, a compound having a function of improving the covering power of developed silver is preferred. Here, the covering power of developed silver refers to the optical density per unit amount of silver. The silver saving agent can be present in the photosensitive layer, the non-photosensitive layer, or any of them. Preferred examples of the silver saving agent include hydrazine derivative compounds, vinyl compounds, phenol derivatives, naphthol derivatives, quaternary onium compounds, and silane compounds. Specific examples thereof include silver saving agents disclosed in paragraphs “0195” to “0235” of JP2003-270755A.

  As the silver saving agent according to the present invention, particularly preferred silver saving agents are compounds represented by the following general formulas (SE1) and (SE2).

General formula (SE1)
Q ₁ -NHNH-Q ₂
In the formula, Q ₁ represents an aromatic group or a heterocyclic group bonded to —NHNH—Q ₂ at a carbon atom site, and Q ₂ represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, Or represents a sulfamoyl group.

In the formula, R ₁ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate group. R ₃ and R ₄ each represents a group that can be substituted on the benzene ring. R ₃ and R ₄ may be connected to each other to form a condensed ring.

In the general formula (SE2), when R ₃ and R ₄ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. When general formula (SE2) is a naphthol compound, R ₁ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ₂ is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

(Thermal solvent)
The dry imaging material of the present invention preferably contains a thermal solvent. Here, the thermal solvent is a material capable of lowering the heat development temperature by 1 ° C. or more compared to the silver salt photothermographic dry imaging material containing no thermal solvent compared to the thermal solvent-containing silver salt photothermographic dry imaging material. It is defined as More preferably, the material can lower the heat development temperature by 2 ° C. or more, and particularly preferably the material that can lower the temperature by 3 ° C. or more. For example, with respect to the photothermographic dry imaging material A containing a thermosolvent, when the photothermographic dry imaging material A from the photothermographic dry imaging material A is B, the photothermographic dry imaging material B is exposed and thermally developed. When the thermal development temperature for obtaining the density obtained by processing at a temperature of 120 ° C. and a thermal development time of 20 seconds with the photothermographic dry imaging material A at the same exposure amount and thermal development time is 119 ° C. or less, To do.

  The thermal solvent has a polar group as a substituent and is preferably represented by the general formula (TS), but is not limited thereto.

General formula (TS)
(Y) _n Z
In General Formula (TS), Y represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Z represents a group selected from a hydroxy group, a carboxy group, an amino group, an amide group, a sulfonamide group, a phosphoric acid amide group, a cyano group, an imide, a ureido, a sulfoxide, a sulfone, a phosphine, a phosphine oxide, or a nitrogen-containing heterocyclic group. . n represents an integer of 1 to 3, which is 1 when Z is a monovalent group, and is the same as the valence of Z when Z is a divalent or higher group. When n is 2 or more, the plurality of Y may be the same or different.

  Y may further have a substituent, and may have a group represented by Z as a substituent. Y will be described in more detail. In general formula (TS), Y is a linear, branched or cyclic alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30, particularly preferably 1 to 25, for example, methyl, ethyl, n -Propyl, iso-propyl, sec-butyl, t-butyl, t-octyl, n-amyl, t-amyl, n-dodecyl, n-tridecyl, octadecyl, icosyl, docosyl, cyclopentyl, cyclohexyl and the like. An alkenyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 25 carbon atoms such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an aryl group (Preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 25 carbon atoms such as phenyl and p-methyl. And a heterocyclic group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms such as pyridyl, pyrazyl, imidazolyl, pyrrolidyl, etc.). Represents.). These substituents may be further substituted with other substituents. These substituents may be bonded to each other to form a ring.

  Y may further have a substituent, and examples of the substituent include a substituent described in “0015” of JP-A No. 2004-21068. The reason why development activity is achieved by using a hot solvent is that the hot solvent melts near the development temperature so that it is compatible with substances involved in development, and the reaction at a lower temperature than when no hot solvent is added. This is thought to be possible. Since heat development is a reduction reaction involving a carboxylic acid having a relatively high polarity or a silver ion transporter, it is preferable to form a reaction field having an appropriate polarity with a thermal solvent having a polar group. .

  The melting point of the thermal solvent preferably used in the present invention is 50 ° C. or more and 200 ° C. or less, more preferably 60 ° C. or more and 150 ° C. or less. In particular, in a photothermographic material that emphasizes stability with respect to an external environment such as image storability as the object of the present invention, a heat solvent having a melting point of 100 ° C. or higher and 150 ° C. or lower is preferable.

  Specific examples of the thermal solvent include compounds described in “0017” of JP-A No. 2004-21068, compounds described in “0027” of US 2002/0025498, MF-1 to MF-3, and MF6. MF-7, MF-9 to MF-12, MF-15 to MF-22.

Preferably the added amount of thermal solvent is 0.01~5.0g / m ² in the present invention, more preferably 0.05~2.5g / m ^2, more preferably 0.1~1.5g / M ² . The thermal solvent is preferably contained in the photosensitive layer. Moreover, although the said thermal solvent may be used independently, you may use it in combination of 2 or more type. In the present invention, the thermal solvent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.

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

  As the solid fine particle dispersion method, the powder of the hot solvent is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibration ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave to produce a solid dispersion. A method is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the Zr content in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem. The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).

(Anti-fogging agent / image stabilizer)
Any constituent layer of the dry imaging material of the present invention includes an antifoggant for preventing fogging during storage before heat development, and an image stabilizer for preventing image deterioration after heat development. It is preferable to contain.

  In the silver salt photothermographic dry imaging material according to the present invention, antifogging and image stabilizers disclosed in many patent publications relating to the imaging material can be used.

  As the reducing agent according to the present invention, reducing agents having protons such as bisphenols and sulfonamidophenols are mainly used, so that these hydrogens are stabilized, the reducing agents are deactivated, and silver ions are reduced. It is preferable that a compound capable of preventing and preventing the reaction is contained. Further, it is preferable that a compound capable of oxidizing and bleaching silver atoms or metallic silver (silver clusters) generated during storage of raw films and images is contained.

  Specific examples of the compound having these functions include, for example, biimidazolyl compounds, iodonium compounds and halogen atoms described in paragraphs “0096” to “0128” of JP-A-2003-270755 as active species. A compound capable of being released, a polymer having at least one repeating unit of a monomer having a halogen radical releasing group as disclosed in JP-A No. 2003-91054, and a vinyl described in paragraph “0013” of JP-A-6-208192 Examples include various antifogging and image stabilizers such as sulfones and / or β-halosulfones and vinyl type inhibitors having an electron-withdrawing group described in Japanese Patent Application No. 2004-234206.

(Toning agent)
The dry imaging material of the present invention forms a photographic image by heat development, and a toning agent (toner) that adjusts the color tone of silver as necessary is dispersed in a normal (organic) binder matrix. It is preferable to contain.

  Examples of suitable toning agents used in the present invention are RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136 and 4,021,249. For example, there are the following.

  Imides (for example, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide); mercaptans (for example, 3-mercapto-1,2,4-triazole); phthalazinone derivatives or metal salts of these derivatives ( For example, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); phthalazine and phthalic acids ( For example, combinations of phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid); phthalazine and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and their anhydrides Products such as phthalic acid, 4-methylphthalic acid, 4-ni The combination and the like with at least one compound selected from Rofutaru acid and tetrachlorophthalic anhydride). Particularly preferred toning agents are combinations of phthalazinone or phthalazine with phthalic acids and phthalic anhydrides.

(Fluorosurfactant)
In the present invention, a fluorine-based surfactant represented by the following general formula (SF) is preferable in order to improve film transportability and environmental suitability (accumulation in a living body) in a laser imager (heat development processing apparatus). Used.

General formula (SF)
(R _f − (L) _n −) _p − (Y) _m − (A)
[In the formula, R _f represents a substituent containing a fluorine atom, L represents a divalent linking group having no fluorine atom, Y represents a (p + q) -valent linking group having no fluorine atom, A represents an anionic group or a salt thereof, n and m each represents an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, n and m are not 0 at the same time. ]
In the general formula (SF), R _f represents a substituent containing a fluorine atom. Examples of the substituent containing the fluorine atom include a fluorinated alkyl group having 1 to 25 carbon atoms (for example, trifluoromethyl). Group, trifluoroethyl group, perfluoroethyl group, perfluorobutyl group, perfluorooctyl group, perfluorododecyl group and perfluorooctadecyl group) or fluorinated alkenyl group (for example, perfluoropropenyl group, perfluorobutenyl group) Perfluorononenyl group, perfluorododecenyl group, etc.). R _f preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. R _f preferably has 2 to 12 fluorine atoms, more preferably 3 to 12 fluorine atoms.

  L represents a divalent linking group having no fluorine atom. Examples of the divalent linking group having no fluorine atom include an alkylene group (for example, a methylene group, an ethylene group, a butylene group, etc.), an alkylene group, and the like. Oxy group (methyleneoxy group, ethyleneoxy group, butyleneoxy group, etc.), oxyalkylene group (for example, oxymethylene group, oxyethylene group, oxybutylene group, etc.), oxyalkyleneoxy group (for example, oxymethyleneoxy group, oxy Ethyleneoxy group, oxyethyleneoxyethyleneoxy group, etc.), phenylene group, oxyphenylene group, phenyloxy group, oxyphenyloxy group, or a combination of these groups.

  A represents an anionic group or a salt thereof, for example, a carboxylic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), a sulfonic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), sulfuric acid half ester Group or a salt thereof (sodium salt, potassium salt and lithium salt), a phosphate group or a salt thereof (sodium salt, potassium salt and the like) and the like.

  Y represents a (p + q) -valent linking group having no fluorine atom. For example, the trivalent or tetravalent linking group having no fluorine atom is composed mainly of a nitrogen atom or a carbon atom. An atomic group is mentioned. n1 represents 0 or an integer of 1, and is preferably 1.

The fluorine-based surfactant represented by the general formula (SF) is an alkyl compound having 1 to 25 carbon atoms into which a fluorine atom is introduced (for example, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorooctyl). Group and a compound having a perfluorooctadecyl group) and an alkenyl compound (for example, a perfluorohexenyl group and a perfluorononenyl group), a trivalent to hexavalent alkanol compound in which no fluorine atom is introduced, and a hydroxyl group, respectively. An anionic group (A) is further introduced into the compound obtained by addition reaction or condensation reaction with 3 to 4 aromatic compounds or hetero compounds (partially _Rf -converted alkanol compound) by, for example, sulfate esterification. Can be obtained.

  Examples of the trivalent to hexavalent alkanol compound include glycerin, pentaerythritol, 2-methyl-2-hydroxymethyl 1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentene, and 1,2,6-hexane. Examples include triol, 1,1,1-tris (hydroxymethyl) propane, 2,2-bis (butanol) -3, aliphatic triol, tetramethylolmethane, D-sorbitol, xylitol, D-mannitol and the like.

  Examples of the aromatic compound and hetero compound having 3 to 4 hydroxyl groups include 1,3,5-trihydroxybenzene and 2,4,6-trihydroxypyridine.

  As a method of adding the fluorosurfactant represented by the general formula (SF) of the present invention to the coating solution, it can be added according to a known addition method. That is, it can be added after being dissolved in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polar solvents such as dimethyl sulfoxide and dimethylformamide. Further, fine particles of 1 μm or less can be dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion and added. Many techniques for fine particle dispersion are disclosed, but they can be dispersed according to these techniques. The fluorine-based surfactant represented by the general formula (SF) is preferably added to the outermost protective layer.

The amount of the fluorosurfactant represented by the general formula (SF) of the present invention is preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol per 1 m ² , and 1 × 10 ⁻⁵ to 1 × 10 ^−2. Mole is particularly preferred. If the range is less than the former range, the charging characteristics may not be obtained. If the range exceeds the former range, the humidity dependency is large and the storage stability under high humidity may be deteriorated.

(Surface layer / surface property modifier, etc.)
The dry imaging material of the present invention is a photosensitive layer in contact with various devices and the photothermographic dry imaging material during winding, rewinding, and transporting of the photosensitive material in a manufacturing process such as coating, drying, and processing. Often undesirably affected by contact between the photothermographic dry imaging materials, such as between the side surface and the backing surface. For example, the surface of the photosensitive material may be scratched or slipped, or the transportability of the photosensitive material in a developing device may be deteriorated.

  Therefore, in the dry imaging material of the present invention, in order to prevent the above-described scratches on the surface and deterioration of transportability, any one of the constituent layers of the material, in particular, the outermost layer on the support is lubricated. It is preferable to adjust the physical properties of the surface of the material by containing an agent, a matting agent and the like.

  In the dry imaging material of the present invention, the outermost layer on the support contains organic solid lubricant particles having an average particle diameter of 1 μm to 30 μm, and the organic solid lubricant particles are dispersed by the polymer dispersant. preferable. The melting point of the organic solid lubricant particles is more preferably higher than the heat development processing temperature, and is 80 ° C. or higher, more preferably 110 ° C. or higher.

  The organic solid lubricant particles used in the silver salt photothermographic dry imaging material of the present invention are preferably compounds that lower the surface energy. For example, polyethylene, polypropylene, polytetrafluoroethylene, and copolymers thereof may be pulverized. The formed particles can be mentioned.

  Examples of organic solid lubricant particles made of polyethylene and polypropylene are shown below, but the present invention is not limited to these.

[Melting point ° C]
PW-1 Polytetrafluoroethylene 321
PW-2 Polypropylene / polyethylene copolymer 142
PW-3 Polyethylene (low density) 113
PW-4 Polyethylene (high density) 126
PW-5 Polypropylene 145
In the dry imaging material of the present invention, the organic solid lubricant particles are particularly preferably compounds represented by the following general formula (OL1).

General formula (OL1)
_{(R 1) p -X 1 -L} -X 2 - (R 2) q
In the formula, R ₁ and R ₂ are each a substituted or unsubstituted alkyl group having 6 to 60 carbon atoms, an alkenyl group, an aralkyl group or an aryl group, and when p or q is 2 or more, a plurality of R ₁ and R 2 are present. ₂ may be the same as or different from each other. X ₁ and X ₂ each represent a divalent linking group containing a nitrogen atom. L represents a substituted or unsubstituted p + q-valent alkyl group, alkenyl group, aralkyl group, or aryl group.

  In the light-sensitive material of the present invention, at least one layer on the support contains the compound represented by the general formula (OL1), and includes a nonionic fluorine-containing surfactant and an anionic fluorine-containing surfactant. It is preferable to contain.

  Although there is no restriction | limiting in particular as a nonionic fluorine-containing surfactant which can be used by this invention, The compound represented with the following general formula (SA) is preferable.

General formula (SA)
Rf _1- (AO) _n -Rf ₂
In the formula, Rf ₁ and Rf ₂ represent a fluorine-containing aliphatic group, and may be the same or different. AO represents a group having at least one alkyleneoxy group, and n represents an integer of 1 to 30.

(Dye, pigment)
In the dry imaging material of the present invention, a filter layer is formed on the same side as or opposite to the photosensitive layer in order to control the amount or wavelength distribution of light transmitted through the photosensitive layer, or a dye or It is preferable to contain a pigment.

  As the dye used, known compounds that absorb light in various wavelength regions can be used depending on the color sensitivity of the photosensitive material.

  For example, when the dry imaging material of the present invention is an image recording material using infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (in this specification, thiopyrylium). It is preferred to use a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. .

  The compound having a squarylium nucleus is a compound having 1-cyclobutene-2-hydroxy-4-one in the molecular structure, and the compound having a croconium nucleus is 1-cyclopentene-2-hydroxy- in the molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Hereinafter, in the present specification, these pigments are collectively referred to as squarylium dyes for convenience. As the dye, a compound described in JP-A-8-201959 is also preferable.

(Support)
Examples of the support material used in the dry imaging material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (aluminum, etc.), etc. A material that can be processed into a flexible sheet or roll is preferred. Therefore, as a support in the photothermographic dry imaging material of the present invention, cellulose acetate film, polyester film, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polyamide film, polyimide film, cellulose triacetate film (TAC) Alternatively, a plastic film such as a polycarbonate (PC) film is preferable, and a biaxially stretched PET film is particularly preferable. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

  In order to improve the charging property, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layer. These may be contained in any layer, but are preferably contained in the backing layer or the surface protective layer on the photosensitive layer side, the undercoat layer and the like. The conductive compounds described in columns 14 to 20 of US Pat. No. 5,244,773 are preferably used. Among these, in the present invention, the surface protective layer on the backing layer side preferably contains a conductive metal oxide.

Here, the conductive metal oxide is crystalline metal oxide particles, and those containing oxygen defects and those containing a small amount of hetero atoms forming a donor with respect to the metal oxide used are generally used. In particular, it is particularly preferable because of its high conductivity, and the latter is particularly preferable because it does not give fog to the silver halide emulsion. Examples of metal oxides are ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O _5, etc., or a composite oxide thereof, especially ZnO, TiO ₂ and SnO ₂ are preferred. As an example of containing a heteroatom, addition Al, or In to ZnO, addition Sb, Nb, P, such as a halogen element relative to SnO _2, In addition, Nb for TiO _2, Ta Etc. are effective. The amount of these different atoms added is preferably in the range of 0.01 to 30 mol%, but particularly preferably 0.1 to 10 mol%. Furthermore, a silicon compound may be added during the production of fine particles in order to improve fine particle dispersibility and transparency.

The metal oxide fine particles used in the dry imaging material of the present invention have electrical conductivity, and the volume resistivity is 10 ⁷ Ω · cm or less, particularly 10 ⁵ Ω · cm or less. These oxides are described in JP-A Nos. 56-143431, 56-120519, 58-62647 and the like. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a conductive material in which the above metal oxide is attached to other crystalline metal oxide particles or fibrous materials (such as titanium oxide) may be used. .

The particle size that can be used is preferably 1 μm or less, but if it is 0.5 μm or less, the stability after dispersion is good and it is easy to use. In order to make the light scattering property as small as possible, it is very preferable to use conductive particles of 0.3 μm or less because a transparent photosensitive material can be formed. Further, when the conductive metal oxide is needle-like or fibrous, the length is preferably 30 μm or less and the diameter is preferably 1 μm or less, particularly preferably the length is 10 μm or less and the diameter is 0.3 μm or less. The thickness / diameter ratio is 3 or more. As the SnO _2, are commercially available from Ishihara Sangyo Kaisha, SNS10M, SN-100P, SN -100D, it may be used FSS10M like.

(Protective layer, back coat layer)
As a binder used in the protective layer and the back coat layer, a polymer having a glass transition point (Tg) higher than that of the photosensitive layer and hardly causing scratches or deformation, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, etc. Are selected from the binders described above.

(Application of component layers)
The dry imaging material of the present invention is preferably formed by preparing a coating solution in which the above-described constituent layers are dissolved or dispersed in a solvent, applying a plurality of coating solutions simultaneously, and then performing a heat treatment. . Here, "multiple simultaneous multi-layer coating" means that a coating solution for each constituent layer (for example, a photosensitive layer, a protective layer) is prepared, and each layer is repeatedly coated and dried when it is coated on a support. Instead, it means that each constituent layer can be formed in such a state that a multilayer coating and drying process can be performed simultaneously. That is, the upper layer is provided before the remaining amount of all the solvents in the lower layer reaches 70% by mass or less (more preferably 90% by mass or less).

  There are no particular restrictions on the method of applying multiple layers simultaneously to each constituent layer, for example, bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, reverse roll coating method, gravure coating method, and extrusion. A known method such as a coating method can be used.

  Of the various methods described above, the slide coating method and the extrusion coating method are more preferable. These coating methods have been described on the side having the photosensitive layer, but the same applies to the case of coating with undercoating when the back layer is provided. Japanese Unexamined Patent Publication No. 2000-15173 has a detailed description on the simultaneous multilayer coating method in the photothermographic dry imaging material.

In the present invention, the silver coating amount is preferably selected in accordance with the purpose of the dry imaging material. However, when the purpose is a medical image, 0.3 g / m ² or more, 1.5 g / m ² or less is preferable, and 0.5 g / m ² or more and 1.5 g / m ² or less are more preferable. Among the applied silver amount, those derived from silver halide preferably occupy 2 to 18%, more preferably 5 to 15%, based on the total silver amount.

In the present invention, the coating density of silver halide grains having a particle diameter of 0.01 μm or more (equivalent particle diameter equivalent to a sphere) is preferably 1 × 10 ¹⁴ particles / m ² or more and 1 × 10 ¹⁸ particles / m ² or less. Furthermore, 1 × 10 ¹⁵ pieces / m ² or more and 1 × 10 ¹⁷ pieces / m ² or less are preferable.

Furthermore, the coating density of the non-photosensitive long-chain aliphatic carboxylate is 1 × 10 ⁻¹⁷ g or more, 1 × 10 1 per silver halide grain of 0.01 μm or more (equivalent particle diameter equivalent to sphere). ^-14 g or less is preferable, and 1 x 10 ^-16 g or more and 1 x 10 ^-15 g or less are more preferable.

  In the case of coating under the conditions within the above range, preferable results are obtained from the viewpoint of the optical maximum density of the silver image per fixed coating silver amount, that is, the silver coating amount (covering power) and the color tone of the silver image. Is obtained.

In the present invention, the dry imaging material preferably contains a solvent in the range of 5 to 1,000 mg / m ² during development. It is more preferable to adjust so that it may be 10-150 mg / m < ² >. As a result, the photothermographic material has high sensitivity, low fog, and high maximum density. Examples of the solvent include those described in paragraph “0030” of JP-A No. 2001-264930. However, it is not limited to these. These solvents can be used alone or in combination of several kinds.

  The content of the solvent in the photothermographic material can be adjusted by changing conditions such as a temperature condition in a drying process after the coating process. Further, the content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

(Odor and pollution prevention technology)
About a preferable aspect as a technique for reducing / preventing odor and contamination caused by volatilization of low molecular weight compounds from the material in the thermal development apparatus (laser imager) during thermal development of the dry imaging material of the present invention explain.

  In the dry imaging material of the present invention, the protective layer preferably has a function of preventing contaminants generated during thermal development from volatilizing or adhering outside the photosensitive material. Therefore, the protective layer binder is preferably a polymer having cellulose acetate having an acetylation degree of 50% to 58% and a vinyl alcohol unit having a saponification degree of 75% or less. In particular, a vinyl acetate polymer and polyvinyl alcohol are preferable.

  As the cellulose acetate, cellulose acetate having an acetylation degree of 50% or more and 58% or less is preferable. On the other hand, the polyvinyl alcohol is preferably a low crystalline polyvinyl alcohol having a saponification degree of 75% or less. The lower limit of the saponification degree is preferably 40%, more preferably 60%.

  Further, the protective layer is used by mixing with a polymer other than the above, for example, a polymer described in US Pat. Nos. 6,352,819, 6,352,820, 6,350,561, etc. You can also. The ratio is preferably 0 to 90% by volume, more preferably 0 to 40% by volume.

  The crosslinking agent for the binder is preferably an isocyanate compound, a silane compound, an epoxy compound, or an acid anhydride.

  Furthermore, it is preferable to reduce the amount of substances that volatilize from the photosensitive material during development by using an acid group scavenger. As an acid group scavenger, an isocyanate system represented by the following general formula (X-1) disclosed in Japanese Patent Application No. 2004-269647, an epoxy system represented by the following general formula (X-2), Mention the phenolic system represented by the following general formula (X-3), the amine system or diamine system represented by the following general formula (X-4), and the carbodiimide system represented by the following general formula (X-5). I can do it. In particular, carbodiimide compounds are preferred.

  In general formulas (X-1) to (X-4), R represents a substituent, R ′ represents a divalent linking group, and n1 represents 1 to 4.

In General Formula (X-5), R ₁ and R ₂ each represent an aryl group or an alkyl group, J ₁ and J ₄ each represent a divalent linking group, and J ₂ and J ₃ each represent an arylene. Represents a group or an alkylene group, L represents a (v1 + 1) -valent alkyl group, alkenyl group, aryl group, heterocyclic group, or a group in which these groups are bonded by a bonding group, v1 represents an integer of 1 or more, n Represents 0 or 1.

(Packaging body)
When storing the dry imaging material of the present invention, a packaging material having a low oxygen permeability and / or moisture permeability in order to prevent concentration changes and fog generation with time, or to improve curling, curling, etc. It is preferable to package with. The oxygen permeability is preferably 50 ml / atm · m ² · day or less at 25 ° C. (where 1 atm is 1.01325 × 10 ⁵ Pa), more preferably 10 ml / atm · m ² · day or less, More preferably, it is 1.0 ml / atm · m ² · day or less. The moisture permeability is preferably 0.01 g / m ² · 40 ° C, relative humidity 90% RH · day or less (according to JIS Z0208 cup method), more preferably 0.005 g / m ² · 40 ° C · relative. The humidity is 90% RH · day or less, more preferably 0.001 g / m ² · 40 ° C. and the relative humidity is 90% RH · day or less.

  Specific examples of packaging materials for dry imaging materials include, for example, JP-A-8-254793, JP-A-2000-206653, JP-A-2000-235241, JP-A-2002-062625, JP-A-2003-015261, JP 2003-057790, JP 2003-084397, JP 2003-098648, JP 2003-098635, JP 2003-107635, JP 2003-131337, JP 2003-146330, JP It is a packaging material described in 2003-226439 and Unexamined-Japanese-Patent No. 2003-228152. The void ratio in the package is 0.01 to 10%, preferably 0.02 to 5%. Nitrogen sealing is performed so that the nitrogen partial pressure in the package is 80% or more, preferably 90% or more. It is good to do. The relative humidity in the package is 10% to 60%, preferably 40% to 55%.

  Further, in the cutting process and the packaging process, in order to prevent image defects such as scratches and white spots, the cleanliness is set to US federal standard 209d class 10,000 as disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-341145. It is preferable to work in the following environment.

(Exposure conditions)
For the exposure used for the exposure of the dry imaging material of the present invention or for the exposure in the image forming method of the present invention, various conditions are employed with respect to the light source, exposure time, etc. suitable for obtaining the desired appropriate image. I can do it.

  The dry imaging material of the present invention preferably uses a laser beam when recording an image. In the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, when the photosensitive material is sensitive to infrared light, it can be applied to any light source as long as it is in the infrared light range. However, the laser power is high, or the silver salt photothermographic dry imaging material In view of, for example, an infrared semiconductor laser (780 nm, 820 nm) is more preferably used.

In particular, the dry imaging material of the present invention exhibits its characteristics when it is exposed for a short time with light of high illuminance, preferably with a light amount of 1 mW / mm ² or more. The illuminance here means the illuminance when the photosensitive material after heat development has an optical density of 3.0. When exposure is performed at such high illuminance, the amount of light (= illuminance * exposure time) required to obtain the required optical density is small, and a high sensitivity system can be designed. More preferably, the amount of light is ² mW / mm ² or more and 50 W / mm ² or less, and more preferably 10 mW / mm ² or more and 50 W / mm ² or less.

Any light source may be used as long as it is as described above, but it can be preferably achieved by using a laser. As a laser preferably used for the photosensitive material of the present invention, a gas laser (Ar ⁺ , Kr ⁺ , He—Ne), a YAG laser, a dye laser, a semiconductor laser, and the like are preferable. A semiconductor laser and a second harmonic generation element can also be used. A blue to violet light emitting semiconductor laser (such as one having a peak intensity at a wavelength of 350 nm to 440 nm) can be used. An example of a blue-violet light emitting high-power semiconductor laser is Nichia's NLHV3000E semiconductor laser.

  In the present invention, the exposure is preferably performed by laser scanning exposure, but various methods can be adopted as the exposure method. For example, as a first preferred method, there is a method using a laser scanning exposure machine in which the angle formed by the exposure surface of the photosensitive material and the scanning laser beam is not substantially perpendicular.

  Here, “substantially not perpendicular” means that the angle closest to the vertical during laser beam scanning is preferably 55 to 88 degrees, more preferably 60 to 86 degrees, and still more preferably 65 to 84 degrees. , Most preferably 70-82 degrees.

  The beam spot diameter on the exposure surface of the photosensitive material when the laser beam is scanned onto the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable in that a smaller spot diameter can reduce the “shift angle” from the vertical of the laser beam incident angle. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as generation of interference fringe-like unevenness.

  As a second method, it is also preferable to perform exposure using a laser scanning exposure machine that emits scanning laser light that is a vertical multi. Compared with a longitudinal single mode scanning laser beam, image quality degradation such as occurrence of interference fringe-like unevenness is reduced. In order to make it vertically multi-ply, a method such as using return light by combining or applying high-frequency superposition is preferable. Note that the vertical multi means that the exposure wavelength is not single, and the exposure wavelength distribution is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

  Furthermore, as a third aspect, it is also preferable to form an image by scanning exposure using two or more laser beams. As such an image recording method using a plurality of laser beams, it is used in an image writing unit of a laser printer or a digital copying machine that writes an image line by line in one scan because of a demand for higher resolution and higher speed. For example, Japanese Patent Laid-Open No. 60-166916 is known. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror and imaged on a photoconductor via an fθ lens or the like. This is in principle the same laser scanning optics as a laser imager or the like. Device.

  The image formation of the laser beam on the photosensitive member in the image writing means of a laser printer or a digital copying machine is one line from the image formation position of one laser beam because the image is written in a plurality of lines by one scanning. The next laser beam is imaged by shifting the distance. Specifically, the two light beams are close to each other on the image plane in the sub-scanning direction at an order of several tens of μm, and the print density is 400 dpi (dpi is the number of dots per inch = 2.54 cm). The sub-scanning direction pitch of the two beams is 63.5 μm, and 42.3 μm at 600 dpi. Unlike the method of shifting the resolution in the sub-scanning direction as described above, in the present invention, it is preferable to form an image by condensing two or more lasers at the same place on the exposure surface while changing the incident angle. At this time, the exposure energy on the exposure surface when writing with one normal laser beam (wavelength λ [nm]) is E, and N laser beams used for exposure have the same wavelength (wavelength λ [nm]). ), In the case of the same exposure energy (En), the range of 0.9 × E ≦ En × N ≦ 1.1 × E is preferable. By doing so, energy is secured on the exposure surface, but the reflection of each laser beam to the image forming layer is reduced because the exposure energy of the laser is low, and thus the occurrence of interference fringes is suppressed.

  In the above description, the wavelengths of the plurality of laser beams are the same as λ, but those having different wavelengths may be used. In this case, it is preferable that (λ−30) <λ1, λ2,... Λn ≦ (λ + 30) with respect to λ [nm].

In the image recording methods of the first, second, and third aspects described above, as lasers used for scanning exposure, generally well-known solid lasers such as ruby lasers, YAG lasers, glass lasers; Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He—Cd laser, N ₂ laser, excimer laser and other gas lasers; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP Semiconductor lasers such as ₂ lasers and GaSb lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner, but among these, semiconductors with a wavelength of 600 to 1200 nm due to maintenance and light source size problems It is preferable to use laser light from a laser. In a laser used in a laser imager or a laser image setter, the beam spot diameter on the exposed surface of a material when scanned with a dry imaging material is generally 5 to 75 μm as a short axis diameter and 5 as a long axis diameter. The laser beam scanning speed can be set to an optimum value for each dry imaging material depending on the sensitivity and laser power at the lasing wavelength inherent to the dry imaging material.

(Laser imager and development conditions)
The laser imager (heat development processing apparatus) referred to in the present invention is configured to supply uniform and stable heat to the entire surface of a film supply unit represented by a film tray, a laser image recording unit, and a dry imaging material. It is composed of a conveying device section from the heat developing device section and the film supply section through laser recording to the discharge of the dry imaging material image-formed by heat development to the outside of the apparatus.

  It is preferable for the rapid processing to shorten the time interval between the exposure processing and the heat development processing. Furthermore, it is preferable that the exposure process and the heat development process proceed simultaneously. That is, in order to start development and proceed with a part of a sheet that has already been exposed while exposing a part of the sheet-sensitive material, the distance between the exposure part where the exposure process is performed and the development part is 0 cm or more and 50 cm or less. In this way, a series of processing time for exposure and development is extremely shortened. A preferable range of this distance is 3 cm or more and 40 cm or less, and more preferably 5 cm or more and 30 cm or less.

  Here, the exposure part refers to a position where light from an exposure light source is irradiated onto the dry imaging material, and the development part refers to a position where the photothermographic material is heated for the first time for thermal development.

  In addition, the conveyance speed in the heat development part of dry imaging material is 20-200 mm / sec, Especially preferably, it is 30-150 mm / sec. By setting the conveyance speed within this range, density unevenness during heat development can be improved and the processing time can be shortened.

  The development conditions for dry imaging materials vary depending on the equipment, equipment, or means used, but typically the development is accomplished by heating the photothermographic dry imaging material imagewise exposed at a suitable high temperature. Is what you do. The development is performed at about 80 to 200 ° C., preferably about 100 to 140 ° C., more preferably 110 to 130 ° C., preferably 3 to 20 seconds, more preferably 5 to 12 seconds.

  The heating during the development processing of the dry imaging material of the present invention is preferably performed by bringing the surface having the protective layer into contact with the heating means for uniform heating, thermal efficiency, and workability. From the viewpoint of the above, it is preferable that the surface having the protective layer is conveyed while being in contact with the heat roller, and is developed by heat treatment.

  The dry imaging material of the present invention has an image obtained by thermal development at a heating temperature of 123 ° C. and a development time of 12 seconds on orthogonal coordinates in which the unit lengths of the diffusion density (Y axis) and the common logarithmic exposure (X axis) are equal. In the characteristic curve shown in FIG. 2, it is preferable that the average gradation of 0.25 to 2.5 in the optical density with diffused light is 2.0 to 4.0. By using such gradation, it is possible to obtain an image with high diagnostic recognizability even if the amount of silver is small.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
<< Preparation of organic silver salt particles >>
Using the apparatus for producing organic silver salt particles as shown in FIG. 1, silver behenate particles were produced as organic silver salt particles by the following method.

(Preparation of silver ion-containing solution)
38295 g of pure water was weighed in the first preparation tank, and 878.6 g of silver nitrate was dissolved to obtain a silver nitrate aqueous solution as a silver ion-containing solution. The aqueous silver nitrate solution was kept at 60 ° C.

(Preparation of organic acid alkali metal salt solution (potassium behenate solution))
35150 g of pure water was weighed in the second preparation tank, heated to 80 ° C., and 1850 g of behenic acid was dissolved when the temperature was stabilized. Thereafter, 1034 ml of a 5 mol / L-KOH aqueous solution was added to obtain a potassium behenate solution as an organic acid alkali metal salt solution.

(Preparation of silver behenate particles)
A silver nitrate aqueous solution prepared in a static mixing device and a potassium behenate solution were mixed at the same time while changing the mixing conditions as shown in Table 1, and stored in a storage tank while stirring at 25 ° C. (circumferential speed 70 m / min). Thereafter, the solution was sent to a centrifuge, and deionized water was added, and washing with deionized water was continued until the conductivity of the drainage reached 30 μS / cm. After washing with water, centrifugal dehydration is performed to remove excess water, and then drying is performed with a hot air circulating dryer at 40 ° C. until there is no mass loss, thereby producing silver behenate particles that are organic silver salt particles. Sample No. 101-108.

  In addition, the temperature of the silver nitrate aqueous solution at the time of supply to a static mixing apparatus was 60 degreeC, and the temperature of the potassium behenate solution was 60 degreeC. (Rapid cooling from 80 ° C. to 60 ° C. at a rate of 20 ° C./min) The supply amount of the silver nitrate aqueous solution is 3.55 L / min, the supply amount of the potassium behenate solution is 3.55 L / min and the Reynolds number ( Re) was added at 6000. The Reynolds number (Re) indicates a value obtained by calculation by the method described in the specification text.

  The static mixing apparatus used was a static mixing apparatus shown in FIG. The supply pipe (for silver nitrate aqueous solution and potassium behenate solution) had an inner diameter of 5 mm and an inner length of 50 mm. The mixed discharge pipe had an inner diameter of 5 mm.

The inner length of the supply pipe is the distance from the axis where the axis of the mixing discharge pipe, the axis of the supply pipe for the aqueous solution of silver nitrate and the axis of the supply pipe for the potassium behenate solution intersect at one point to the coincidence point where the axes coincide. Say length. The inner length of the mixed discharge pipe coincides with the axis where the axis of the mixed discharge pipe, the axis of the silver nitrate aqueous solution supply pipe, and the axis of the potassium behenate solution supply pipe intersect at one point. From this point, the length until the two liquids passing through the axis of the silver nitrate aqueous solution supply pipe and the potassium behenate solution supply pipe are discharged from the mixing discharge pipe is compared. 109 Production>
Samples No. 1 were used except that the manufacturing apparatus shown in FIG. 1 was used and no vibration was applied to the mixing discharge pipe of the static mixing apparatus. Silver behenate particles were produced under the same conditions as in No. 101, and Comparative Sample No. 109.

<Comparative Silver Behenate Particle No. 110 Production>
Using the production apparatus shown in FIG. 4, silver behenate particles were produced under the following conditions.

(Preparation of silver ion-containing solution)
Silver behenate particles No. An aqueous silver nitrate solution having the same concentration as when 101 was produced was prepared and kept at 60 ° C.

(Preparation of organic acid alkali metal salt solution (potassium behenate solution))
35150 g of pure water was weighed in the main body of the production apparatus, heated to 80 ° C., and 1850 g of behenic acid was dissolved when the temperature was stabilized. Thereafter, 1034 ml of a 5 mol / L-KOH aqueous solution was added to obtain a potassium behenate solution as an organic acid alkali metal salt solution.

(Preparation of silver behenate particles)
While stirring the potassium behenate solution prepared in the main body of the manufacturing apparatus with a stirring member and a high-speed rotary centrifugal radiation stirrer (dispers mixer), the prepared silver nitrate aqueous solution is supplied at a temperature of 60 ° C. and supplied at a supply rate of 20 L / min. After that, the solution was sent to a centrifuge, and deionized water was added, and washing with deionized water was continued until the conductivity of the drainage reached 30 μS / cm. After washing with water, centrifugal dehydration is performed to remove excess water, and then drying is performed with a hot air circulating dryer at 40 ° C. until there is no mass loss, thereby producing silver behenate particles that are organic silver salt particles. Comparative sample No. 110. The peripheral speed of the stirring member was 2 m / sec, and the peripheral speed of the high-speed rotating centrifugal radiation type stirrer (disperser) was 18.5 m / sec.

Evaluation Each sample No. Table 1 shows the results of evaluating the coefficient of variation of the particle thickness and the particle size by electron micrographing as the shape of silver behenate salt particles 101 to 110. Note that the coefficient of variation of the particle thickness and the particle size by electron micrographs was performed according to the method described in the text.

  As is apparent from Table 1, the organic silver salt particles obtained by the production method of the present invention have a reduced particle size and improved monodispersibility. The effectiveness of the present invention was confirmed.

Example 2
A silver salt photothermographic dry imaging material was prepared by the following method.

《Preparation of underdrawn support》
8 W / m ^{2 on} both sides of a commercially available biaxially stretched heat-fixed thickness of 175 μm and an optical density of 0.170 (measured with a Densitometer PDA-65 manufactured by Konica Minolta, Inc.) with a blue dye.・ Corona discharge treatment was applied for one minute, and the following undercoat coating solution a-1 was applied on one surface to a dry film thickness of 0.8 μm and dried to form an undercoat layer A-1, and on the other side The undercoat coating solution b-1 shown below was coated on the surface so as to have a dry film thickness of 0.8 μm and dried to form an undercoat layer B-1.

<Undercoat coating liquid a-1>
Copolymer latex liquid of butyl acrylate (30% by mass) / t-butyl acrylate (20% by mass) / styrene (25% by mass) / 2-hydroxyethyl acrylate (25% by mass) (solid content 30%) 270 g
(C-1) 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1L with water <Undercoating liquid b-1>
270 g of copolymer latex liquid (30% solid content) of butyl acrylate (40 mass%) / styrene (20 mass%) / glycidyl acrylate (40 mass%)
(C-1) 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1L with water.

Subsequently, a corona discharge of 8 W / m ² · min is applied to the upper surfaces of the undercoat layer A-1 and the undercoat layer B-1, and the following undercoat upper layer coating solution a is applied on the undercoat layer A-1. -2 as an undercoat upper layer A-2 so that the dry film thickness is 0.1 μm, and the following undercoat upper layer coating solution b-2 is formed on the undercoat layer B-1 so that the dry film thickness is 0.4 μm. Was coated as an undercoat upper layer B-2 having an antistatic function.

<Undercoating upper layer coating solution a-2>
Mass to become gelatin 0.4g / m ² (C-1) 0.2g
(C-2) 0.2g
(C-3) 0.1 g
Silica particles (average particle size 3μm) 0.1g
Finish to 1L with water <Undercoating upper layer coating solution b-2>
Sb-doped SnO2 (SNS10M; manufactured by Ishihara Sangyo Co., Ltd.) 60 g
80 g of latex liquid (solid content 20%) containing (C-4) as a component
Ammonium sulfate 0.5g
(C-5) 12g
Polyethylene glycol (mass average molecular weight 600) 6g
Finish to 1L with water.

<< Preparation of backcoat layer coating solution >>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (Eastman Chemical, CAB381-20) and 4.5 g of a polyester resin (Bostic, VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved liquid, and 4.5 g of F surfactant (Asahi Glass Co., Surflon KH40) dissolved in 43.2 g of methanol and F surfactant (large 2.3 g of Nippon Ink Co., Ltd. (MegaFag F120K) was added and stirred well until dissolved. Next, oleyl oleate was added at 2 and 5 g. Finally, 75 g of silica (WR Grace, Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% by mass with a dissolver type homogenizer was added and stirred to prepare a backcoat layer coating solution.

<< Preparation of backcoat layer protective layer coating liquid >>
Cellulose acetate butyrate (10% methyl ethyl ketone solution) 15 g
Monodispersed 15% monodispersed silica (average particle size: 8 μm, surface treatment with 1% by mass of aluminum based on the total mass of silica) 0.030 g
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.05 g
C ₉ F ₁₇ —C ₆ H ₄ —SO ₃ Na 0.01 g
Stearic acid 0.1g
Oleyl oleate 0.1g
α-Alumina (Mohs hardness 9) 0.1g
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared in this way were extruded with a coater at an application rate of 50 m / min so that the dry film thickness was 3.5 μm. The undercoating upper layer B-2 was applied. The drying was performed for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C.

<< Preparation of silver halide grain emulsion >>
[Preparation of silver halide grain emulsion 1]
(Solution A1)
Phenylcarbamoylated gelatin 88.3g
Compound A (* 1) (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finished with water to 5429 ml.

(Solution B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(Solution C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finished to 660 ml with water.

(Solution D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
K ₃ IrCl ₆ (equivalent to 4 × 10 ⁻⁵ mol / Ag) 50.0 ml
Finished to 1982 ml with water.

(Solution E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount (Solution F1)
Potassium hydroxide 0.71g
Finished to 20 ml with water.

(Solution G1)
56% acetic acid aqueous solution 18.0 ml
(Solution H1)
Anhydrous sodium carbonate 1.72 g
Finished to 151 ml with water.

(* 1) Compound _{A: HO (CH 2 CH 2} O) n (CH (CH 3) CH 2 O) 17 (CH 2 CH 2 O) m H (m + n = 5~7)
Using the mixing stirrer described in JP-B-58-58288, the solution A1 was mixed with a 1/4 amount of the solution B1 and the total amount of the solution C1 at 35 ° C. and a pAg of 8.09. Addition took 45 minutes to nucleate. After 1 minute, the entire amount of solution F1 was added. During this time, the pAg was adjusted as appropriate using the solution E1. After the elapse of 6 minutes, 3/4 amount of the solution B1 and the whole amount of the solution D1 were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling to pAg8.09. After stirring for 5 minutes, the entire amount of the solution G1 was added to precipitate the silver halide emulsion. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, the silver halide emulsion was allowed to settle. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution H1 was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount of silver was 1161 g per mole of silver to obtain silver halide grain emulsion 1.

  The silver halide grains in the silver halide grain emulsion 1 prepared as described above are monodispersed cubic iodine having an average sphere equivalent diameter of 0.045 μm, a coefficient of variation of sphere equivalent diameter of 12%, and a [100] face ratio of 92%. Silver bromide grains. The average sphere equivalent diameter and the coefficient of variation of the sphere equivalent diameter were determined from an average of 1000 particles using an electron microscope. The [100] face ratio of the particles was determined using the Kubelka-Munk method.

  The ratio of silver halide grains having an average grain size of 0.001 μm or more and 0.050 μm or less in the silver halide emulsion 1 was 61% by mass of the total silver halide grains in terms of silver amount.

(Synthesis of polymer A for dispersing silver halide grains)
A 0.5 liter four-necked separable flask was equipped with a dropping device, a thermometer, a nitrogen gas inlet tube, a stirring device and a reflux condenser, and 50 g of methyl ethyl ketone and a monomer other than NIPAM having a composition ratio shown in Table 2 ( Unit g) was charged and heated to 80 ° C. Further, a solution prepared by dissolving NIPAM (unit: g) shown in Table 2 and 0.12 g of lauryl peroxide in 43 g of methyl ethyl ketone was dropped into the flask over 2 hours. Thereafter, when the temperature was raised over 1 hour to reach a reflux state, a solution obtained by dissolving 0.17 g of lauryl peroxide in 33 g of methyl ethyl ketone was dropped into the flask over 2 hours and reacted at the same temperature for further 3 hours. . Thereafter, a solution obtained by dissolving 0.33 g of methyl hydroquinone in 107 g of methyl ethyl ketone was added and cooled, and a polymer A solution for dispersing silver halide grains having a polymer content of 30% by mass was obtained.
BLEMMER PME-400: Methacrylate with — (EO) _m —CH ₃ (m≈9) BLEMMER PSE-400: Methacrylate with — (EO) _m —C ₁₈ H ₃₇ (m≈9) , EO; ethyleneoxy group) (The above two types are manufactured by NOF Corporation)
NIPAM: N-isopropylacrylamide (manufactured by Kojin Co., Ltd.)
DAAM: Diacetone acrylamide (manufactured by Kyowa Hakko Kogyo Co., Ltd.)

<< Preparation of dispersed silver halide emulsion in MEK >>
(MEK dispersed silver halide emulsion 1)
25 g of the polymer A solution was added dropwise to 10 times the amount of pure water, precipitated, filtered, and washed and purified. The obtained polymer precipitate was dissolved in methanol to finish the total amount to 121 g. While stirring the methanol solution of the polymer at 45 ° C., silver halide grain emulsion 1 (59.2 g) adjusted to 45 ° C. was added dropwise over 20 minutes, and further stirred for 30 minutes. Thereafter, the temperature was lowered to 35 ° C. over 30 minutes, and then 777 g of methyl ethyl ketone (MEK) adjusted to 35 ° C. was added dropwise over 30 minutes to obtain MEK-dispersed silver halide grain emulsion 1.

(MEK-dispersed silver halide grain emulsion 2)
Water and methanol were removed from the above dispersed silver halide emulsion 1 in MEK according to the following method. Using a ceramic ultrafiltration membrane manufactured by Noritake Engineering Co., Ltd. (pore diameter 20 nm, membrane area 0.0055 m ² ), MEK-dispersed silver halide grain emulsion 1 is concentrated to 1/2 in terms of mass. The ultrafiltration method was a cross flow method, the operation conditions were a circulation flow rate of 1 L / min, and the operation pressure was negative pressure filtration that reduced the pressure on the filtration side to 2.13 × 10 ⁴ Pa. Since the pore size of the membrane is sufficiently smaller than the particle size of silver halide grains and the polymer used for dispersion, water, methanol, and further solvent components such as methyl ethyl ketone permeate through the filtrate. After ½ concentration, an operation of adding an equal amount of methyl ethyl ketone to that which had been concentrated was repeated four times to remove water and methanol to obtain dispersed silver halide grain emulsion 2 in MEK. The water and methanol contents after removal were 1.0% and 0.8%, respectively.

<< Preparation of silver behenate particle pre-dispersion >>
A silver behenate particle preliminary dispersion was prepared by the following method.

(Preparation of silver behenate particles)
Silver behenate particles No. 1 prepared in Example 1 were used. No. 101-110 under the same conditions, the same silver behenate particles were prepared. a to j.

(Preparation of silver behenate particle pre-dispersion)
Each silver behenate particle No. dried with 26.26 g of polyvinyl butyral powder (Sekisui Chemical Co., Ltd., ESREC BL-5) dissolved in 2000 g of methyl ethyl ketone and stirred with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN . No. 2-a to 2-j were gradually added and mixed thoroughly to prepare a silver behenate particle pre-dispersion. 2a to 2j.

(Preparation of silver behenate particle dispersion)
The prepared silver behenate particle preliminary dispersion No. Media type disperser DISPERMAT SL-C12EX filled with 80% of the internal volume of 0.5 mm diameter zirconia beads (Toray Seles made by Toray) so that the residence time in the mill is 1.5 minutes using pumps 2a to 2j Is supplied to a mold (made by VMA-GETZMANN) and dispersed at a mill peripheral speed of 8 m / s to prepare a silver behenate particle dispersion which is a non-photosensitive organic acid silver salt particle. 2-a to 2-j.

[Preparation of each additive]
(Preparation of stabilizer solution)
1.0 g of Stabilizer 1 and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare a stabilizer solution.

(Preparation of infrared sensitizing dye solution)
19.2 mg of infrared sensitizing dye 1, 1.488 g 2-chloro-benzoic acid, 2.7779 g stabilizer 2 and 365 mg 5-methyl-2-mercaptobenzimidazole in 31.3 ml MEK in the dark And an infrared sensitizing dye solution was prepared.

(Preparation of supersensitizer solution)
50.1 mg of supersensitizer 1 was dissolved in 8.8 g of methanol to prepare a supersensitizer solution.

(Preparation of additive solution a)
27.98 g of the reducing agent (A-8), 1.54 g of 4-methylphthalic acid, and 0.48 g of infrared dye 2 were dissolved in 110 g of MEK to obtain an additive solution a.

(Preparation of additive liquid b)
3.56 g of antifoggant 2 and 3.43 g of phthalazine were dissolved in 40.9 g of MEK to obtain additive solution b.

[Preparation of coating solution for forming photosensitive layer]
Under an inert gas atmosphere (97% nitrogen), each prepared silver behenate particle dispersion No. 50 g of 2-a to 2-j, 10 g of the MEK-dispersed silver halide emulsion 2 and 5.11 g of MEK were kept at 21 ° C. with stirring, and antifoggant-1 (10% methanol) 390 μl of solution) was added and stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 20 minutes. Subsequently, 167 μl of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While maintaining the temperature at 13 ° C., 13.31 g of polyvinyl butyral (Butvar B-79) was added as a binder resin and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4 mass% methyl ethyl ketone solution) was added. And stirred for 15 minutes. While continuing to stir, 12.43 g of additive a, 1.6 ml of Desmodur N3300 (Moby aliphatic isocyanate 10% methyl ethyl ketone solution) and 4.27 g of additive b were sequentially added and stirred. A coating solution for forming a photosensitive layer was prepared. 2-1 to 2-10.

[Preparation of matting agent dispersion]
Cellulose acetate butyrate (Eastman Chemical Co., 7.5 g CAB171-15) was dissolved in 42.5 g of MEK, and 5 g of calcium carbonate (Speciality Minerals, Super-Pflex 200) was added thereto, and a dissolver type homogenizer was used. A matting agent dispersion was prepared by dispersing at 8000 rpm for 30 minutes.

[Preparation of surface protective layer coating solution]
While stirring MEK865g, cellulose acetate butyrate (Eastman Chemica, CAB171-15) 96g, polymethylmethacrylic acid (Rohm & Haas, Paraloid A-21) 4.5g, vinyl sulfone compound (HD-1) 1. 5 g, 1.0 g of benzotriazole, and 1.0 g of F-based surfactant (Asahi Glass Co., Surflon KH40) were added and dissolved. Next, 30 g of the above matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

[Production of silver salt photothermographic dry imaging materials]
(Photosensitive layer side coating)
The prepared photosensitive layer coating solution No. The 2-1 to 2-10 and the surface protective layer coating solution were simultaneously applied in multiple layers using a known extrusion coater. The coating was carried out so that the photosensitive layer had a silver coating amount of 1.7 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm. Thereafter, drying was performed for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C. to produce a silver salt photothermographic dry imaging material. 201-210.

Evaluation Each sample No. Table 3 shows the results of evaluation of photographic performance (fogging density) and density unevenness attached to 201-210.

Method for evaluating fog density From the photosensitive layer side of the silver salt photothermographic dry imaging material, exposure by laser scanning is given by an exposure machine using a semiconductor laser having a longitudinal multimode wavelength of 800 nm to 820 nm as a light source by superposition of high frequency. It was. At this time, an image was formed by setting the angle of the exposure surface of the photothermographic dry imaging material and the exposure laser beam to 75 degrees. Thereafter, using an automatic developing machine having a heat drum, the surface protective layer of the silver salt photothermographic dry imaging material and the drum surface were brought into contact with each other, and heat development was performed at 123 ° C. for 12.5 seconds. At that time, exposure and development were performed in a room adjusted to 23 ° C. and 50% RH. The obtained image was measured with a densitometer, and the fog density (unexposed area density, Dmin) was measured.

Density non-uniformity evaluation Density non-uniformity evaluation of silver salt photothermographic dry imaging materials on Schaukasten ○: No density non-uniformity △: Density non-uniformity but no problem in diagnosis ×: Density non-uniformity presents a problem in diagnosis

  In the table, A *: silver behenate particles, B *: silver behenate particle preliminary dispersion, C *: silver behenate particle dispersion, D *: coating solution for forming a photosensitive layer.

  Thus, it can be seen that the organic silver salt particles obtained by the production method of the present invention are low in fog and have improved density unevenness. The effectiveness of the present invention was confirmed.

It is a schematic diagram of the manufacturing apparatus of the organic silver salt particle | grains of this invention. It is a schematic perspective view which shows an example of the static mixing apparatus shown by FIG. It is a schematic sectional drawing of the silver salt photothermographic dry imaging material of this invention. It is a schematic diagram of the manufacturing apparatus of the organic silver salt which has the conventional gas / liquid interface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Manufacturing apparatus 11 1st preparation tank 11c, 12c Liquid feed pump 11d, 12d Flow rate detector 12 2nd preparation tank 13 Static mixing apparatus 13a, 13b Supply pipe 13c Mixing discharge pipe 13d Vibration means 14a 1st heat exchanger 14b 2nd heat exchanger 15 Storage tank 201 Reactor body 202 Stirring member 203 High-speed rotation centrifugal radiation type stirrer (disperser)
3 Silver salt photothermographic dry imaging material 301 Support 302 Photosensitive layer 303 Non-photosensitive layer 304 Backcoat layer θ1, θ2 Angle P Intersection L Length

Claims (6)

A silver ion-containing solution prepared using at least water or a mixture of water and an organic solvent as a solvent, and an organic acid alkali metal salt solution or suspension prepared using water, an organic solvent, or a mixture of water and an organic solvent as a solvent. In an apparatus for producing organic silver salt particles, in which two liquids are mixed to produce organic silver salt particles,
The supply pipe and the mixed discharge pipe are connected so that the axes of the two liquid supply pipes intersect with the axis of the mixed discharge pipe that mixes and discharges them at one point, and the axes coincide at the intersection. Have a static mixing device,
The said static mixing apparatus has a vibration provision means, The manufacturing apparatus of the organic silver salt particle characterized by the above-mentioned. The apparatus for producing organic silver salt particles according to claim 1, wherein the vibration applying means is an ultrasonic generator. A silver ion-containing solution prepared using at least water or a mixture of water and an organic solvent as a solvent, and an organic acid alkali metal salt solution or suspension prepared using water, an organic solvent, or a mixture of water and an organic solvent as a solvent. In the method for producing organic silver salt particles in which two liquids are mixed to produce organic silver salt particles,
In the mixing of the two liquids, the axes of the plurality of supply pipes of the two liquids and the axis of the mixing discharge pipe for mixing and discharging the two liquids intersect at one place, and the axes coincide at the intersection. A method for producing organic silver salt particles, which is carried out while applying vibrations in a static mixing device having vibration applying means connected to a discharge pipe. The method for producing organic silver salt particles according to claim 3, wherein the vibration applying means is an ultrasonic generator. Photosensitive silver halide particles, a reducing agent capable of reducing silver ions, a binder, and organic silver salt particles produced by the method for producing organic silver salt particles according to claim 3 or 4 on a support. A silver salt photothermographic dry imaging material comprising a layer. An image forming method based on digital image information, wherein a silver image is formed using the silver salt photothermographic dry imaging material according to claim 5.

Images