JP2007112718A - Method and apparatus for producing organic acid metal salt particle, and silver salt photothermographic dry imaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing organic acid metal salt particles excellent in mono-dispersion property of particle diameter distribution, further, a method of production, capable of producing the organic acid silver salt particles for a silver salt photothermographic dry imaging material excellent in mono-dispersion property of the particle diameter distribution, generating less fogging and excellent in applying property, and the silver salt photothermographic dry imaging material by using the organic acid silver salt particles obtained by the method of production. <P>SOLUTION: This method for producing the organic acid metal salt particles by mixing and weighing at the same time an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt with an aqueous metal salt solution containing the metal ion capable of interchanging with the alkali metal of the organic acid alkali metal salt is provided by mixing and weighing at the same time the aqueous solution or suspension of the organic acid and organic acid alkali metal salt having ≥1 and ≤10 mPa s viscosity with an aqueous metal salt solution containing the metal ion capable of interchanging with the alkali metal of the organic acid alkali metal salt having ≥1 and ≤10 mPa s viscosity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing organic acid metal salt particles, and in particular, a silver salt photothermographic dry imaging material (photothermographic dry imaging material, photothermographic material, photothermographic material, simply referred to as photothermographic material or photosensitive material). The present invention relates to a method for producing organic acid silver salt particles contained in a silver salt photothermographic dry imaging material using the organic acid silver salt particles.

  In recent years, imaging (image forming) materials are 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. Also 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, page 48, 1991) and the like. A silver salt photothermographic dry imaging material containing a photosensitive organic acid silver salt, photosensitive silver halide grains and a silver ion reducing agent is known. Since this silver salt photothermographic dry imaging material does not use any solution processing chemicals in the development process, it has the advantage of providing a user with a simpler system that does not impair the environment.

  These silver salt photothermographic dry imaging materials use photosensitive silver halide particles installed in a photosensitive layer as a photosensor, use organic acid silver salt as a silver ion supply source, and usually have a built-in reducing agent. An image is formed by heat development at ˜140 ° C., and fixing is not performed.

  However, since the silver salt photothermographic dry imaging material contains an organic acid 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 acid silver salt, reducing agent, etc. remain even after heat development. In the long-term storage process, there is a problem that metallic silver is generated by heat or light, and the image quality such as the color tone of the silver image easily changes.

  By the way, the organic acid silver salt used as the non-photosensitive silver source in the above-mentioned silver salt photothermographic dry imaging material is basically an alkaline soap obtained by adding an aliphatic carboxylic acid to a caustic alkali or alkali metal salt in water, and then the alkali soap. It is prepared by adding silver nitrate to replace silver with soap (organic acid silver salt) (see, for example, Patent Documents 1 and 2). In addition, alcohol may be added to enhance the concentration effect and uniformity (see, for example, Patent Document 3).

  Since the alkaline soap is alkaline, the silver soap is made at a high pH. However, the addition of silver nitrate to the alkaline solution generates silver oxide as a by-product, and also causes unintended silver nuclei. Such a by-product is disadvantageous in terms of the performance of silver salt photothermographic dry imaging materials, particularly in terms of fogging.

  As a method and apparatus for forming organic acid silver salt particles that solve the above-mentioned problems, Japanese Patent Laid-Open Nos. 2001-33907, 2001-83652, and 2001-31870 use a closed mixing means. Is disclosed. However, although these means exhibit a certain degree of effect, the closed mixing means has an agitation means inside, and therefore, the structure becomes complicated and, when viewed microscopically, the liquid stays. Such problems 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 acid silver salt particles, but also increases the fog by exposing the retained particles to high concentrations of silver ions. It also causes the problem.

  On the other hand, in order to produce a silver salt photothermographic dry imaging material using organic acid silver salt particles, it is necessary to disperse the organic acid silver salt particles in a binder to form a coating film. In this case, it is known that many problems relating to film forming properties and coating properties occur as compared with ordinary silver halide grains. This is considered to be due to the fact that the proportion of the organic acid silver salt particles occupied in the binder is large due to the large volume of the organic acid silver salt particles per mole. At present, there is known a method for dealing with the problem by increasing the binder ratio, but as a result, it has many adverse effects such as affecting the photographic performance.

  Although JP 2001-163890 discloses conditions for the addition amount of a silver ion solution and an alkali metal salt solution of an aliphatic carboxylic acid, it does not mention a solution for the problem of coating properties. Accordingly, problems relating to applicability such as density unevenness are fatal problems in medical diagnosis, and an early solution is desired.

  Japanese Patent Application Laid-Open No. 2003-43607 discloses a method for producing organic acid silver salt particles using a micromixer. The micromixer is a static mixing that does not have a stirring means inside, and is specifically a device that performs laminar flow in a microchannel. The laminar flow refers to a flow in which each particle of the fluid moves in parallel in the flow direction, and therefore nuclei cannot be generated in a uniform state unless the concentration of the additive solution is reduced. Therefore, the particle size distribution of the organic acid silver salt particles is deteriorated, and there is a problem of increase in fog. Further, since the concentration of the additive solution is reduced and the additive solution is sent into the microchannel to form a laminar flow, the productivity is also deteriorated.

In addition, a method is disclosed in which the mixing of the raw material reaction liquid is made uniform by using a mixing device having a specific structure and the monodispersity of the particle size distribution of the organic acid silver salt particles is improved (see, for example, Patent Document 4). ). However, this method is still insufficient and further improvement is desired.
JP 2000-143578 A Japanese Patent No. 3069294 JP 2000-7683 A Japanese Patent Laying-Open No. 2005-157190

  Therefore, the present invention has been made in view of the above circumstances, and its purpose is first to provide a method for producing organic acid metal salt particles excellent in monodispersity of particle size distribution, Secondly, it is to provide a production method capable of producing organic acid silver salt particles for silver salt photothermographic dry imaging materials which are excellent in monodispersity of particle size distribution, less fogging, and excellent in coating properties. . Moreover, it is providing the silver salt photothermographic dry imaging material using the organic acid silver salt particle manufactured by the manufacturing method.

  The above object of the present invention can be achieved by the following configuration.

  1. Production of organic acid metal salt particles in which an aqueous solution or suspension of an organic acid and an alkali metal salt of an organic acid and a metal salt aqueous solution containing a metal ion capable of exchange reaction with the alkali metal of the organic acid alkali metal salt are simultaneously metered and mixed. In the method, an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt having a viscosity of 1 mPa · s to 10 mPa · s and an alkali metal of the organic acid alkali metal salt having a viscosity of 1 mPa · s to 10 mPa · s. A method of producing organic acid metal salt particles, comprising simultaneously metering and mixing a metal salt aqueous solution containing a metal ion capable of exchange reaction.

  2. A manufacturing apparatus having a static mixing device in which the mixing discharge pipe and the supply pipe are connected so that the axis of the mixing discharge pipe and the axes of the plurality of supply pipes intersect at one point and the axes coincide at the intersection. 2. The method for producing organic acid metal salt particles according to 1 above, wherein the simultaneous metering and mixing are performed.

  3. The organic acid and the mixed acid discharge pipe and the supply pipe are connected to each other so that the axis of the mixed discharge pipe and the plurality of supply pipes intersect at one point, and the axes coincide at the intersection. In the method for producing organic acid metal salt particles, an aqueous solution or suspension of an organic acid alkali metal salt and a metal salt aqueous solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt are simultaneously metered and mixed. Conditions for cooling an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt from a high temperature (70 ° C. to 100 ° C.) to a low temperature (0 ° C. to 60 ° C.) at a cooling rate of 1 ° C./min to 1000 ° C./min. The manufacturing method of the organic acid metal salt particle characterized by the above-mentioned.

  4). 4. The method for producing organic acid metal salt particles as described in 3 above, wherein the cooling rate is from 10 ° C./min to 1000 ° C./min.

  5. 5. The method for producing organic acid metal salt particles according to 3 or 4, wherein the cooling is performed using an online heat exchanger.

  6). 6. The method for producing organic acid metal salt particles according to any one of 1 to 5, wherein the organic acid is a fatty acid.

7). An apparatus for producing organic acid metal salt particles, comprising at least the following devices (1) to (4):
(1) a first supply device for supplying an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt to a static mixing device; (2) an organic acid and an organic acid alkali metal salt supplied to the static mixing device; A cooling device that cools the aqueous solution or suspension; (3) a second supply device that supplies an aqueous metal salt solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt to a static mixing device; 4) A static mixing device that mixes the supplies from the first supply device and the second supply device and discharges the organic acid metal salt-containing liquid. 8. The apparatus for producing organic acid metal salt particles as described in 7 above, wherein the organic acid is a fatty acid.

  9. At least one or more types of photosensitive silver halide particles, a silver ion reducing agent, a binder, and an organic acid produced by the method for producing organic acid metal salt particles according to any one of 1 to 6 above on a support. A silver salt photothermographic dry imaging material comprising a photosensitive layer containing acid silver salt particles.

  According to the above configuration of the present invention, first, a method for producing organic acid metal salt particles excellent in monodispersity of particle size distribution can be provided. Second, the present invention provides a production method capable of producing organic acid silver salt particles for silver salt photothermographic dry imaging materials having excellent monodispersibility of particle size distribution, less fogging, and excellent coating properties, and its A silver salt photothermographic dry imaging material using organic acid silver salt particles produced by the production method can be provided.

  Hereinafter, the present invention and components of the present invention will be described.

(Method for producing organic acid metal salt particles)
The organic acid metal salt according to the present invention comprises an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt, and an aqueous metal salt solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt. It is manufactured by mixing under specific conditions.

  The organic acid according to the present invention 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. Furthermore, a long chain aliphatic carboxylic acid is preferable, and carbon number is preferably 10 to 30, more preferably 10 to 26.

  The organic acid according to the present invention may have either 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.

  Examples of the alkali metal for forming the alkali metal salt of the organic acid according to the present invention include lithium, sodium, potassium, rubidium, cesium, and francium. Of these, sodium and potassium are preferred. Particularly preferred is potassium.

  The organic acid alkali metal salt is prepared by adding NaOH, KOH or the like to the organic acid. At this time, it is preferable that the amount of alkali is equal to or less than the amount of organic acid to leave 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.

  In addition, the density | concentration of the aqueous solution or suspension of the organic acid and organic acid alkali metal salt which concerns on this invention becomes like this. Preferably it is 0.1-30 mass%, More preferably, it is 1-10 mass%.

  The organic acid metal salt according to the present invention means an organic acid metal salt obtained by exchanging the alkali metal of the alkali metal salt of the organic acid with a metal such as a transition metal or a typical metal by an exchange reaction. For example, organic acid silver salt, organic acid gold salt, organic acid zinc salt, organic acid nickel salt, etc. are mentioned. Among these, the production method of the present invention can be preferably applied to the production of organic acid silver salts, particularly fatty acid silver salts.

  The viscosity of each of the aqueous solution or suspension of the organic acid and organic acid alkali metal salt used in the organic acid metal salt formation reaction and the aqueous solution of the metal salt is sufficiently small and preferably has the same viscosity (preferably 1 mPa · s 10 mPa · s or less). By satisfying such conditions, the mixing property of the reaction solution is improved, and monodispersed / fogged-reduced particles can be formed.

  In addition, the metal salt aqueous solution containing a metal ion capable of exchange reaction with an alkali metal of an organic acid alkali metal salt has a sufficiently low viscosity (about 1 to 5 cp) in a practical concentration range, but an organic acid and an organic acid alkali metal. An aqueous salt solution or suspension has a high viscosity (30 to 300 cp) at a practical concentration considering productivity.

  Using an organic solvent or a mixture of water and an organic solvent as a solvent for the organic acid alkali metal salt can reduce the viscosity to some extent, but is not environmentally preferable. In general, it is considered effective to keep the organic acid alkali metal salt solution at 60 ° C. or higher in order to avoid the phenomenon of crystallization and solidification (see, for example, JP-A-2001-33907).

  However, as a result of intensive studies by the present inventors, the aqueous solution or suspension of fatty acid and fatty acid alkali metal salt is rapidly cooled from a high temperature (70 ° C. to 100 ° C.) to a low temperature (0 ° C. to 60 ° C.). The present inventors have found that it is possible to reduce the viscosity without forming and solidifying, and have reached the present invention.

(Organic acid metal salt production equipment)
Hereinafter, as a typical example of the organic acid metal salt according to the present invention, a method and an apparatus for producing organic acid silver salt particles, particularly fatty acid silver salt particles, will be described in detail, but the present invention is limited to the embodiments described below. Not.

  In the production method of the present invention, in an apparatus for producing organic acid silver salt particles using a silver ion-containing solution and an organic acid alkali metal salt solution, the preparation tank of the silver ion-containing solution and the organic acid alkali metal salt solution By adopting a structure characterized by having a static mixing device in which each solution from the preparation tank is simultaneously and quantitatively supplied through a quantitative supply device, the particle size distribution is monodisperse and the occurrence of fog is small, and coating is performed. The manufacturing apparatus which can manufacture the organic acid silver salt particle | grains excellent in property can be provided.

  It is desirable to uniformly mix each solution of an organic acid and an organic acid alkali metal salt solution or suspension and a metal salt solution. The mixing method of each liquid may be any method such as batch method, continuous method, external circulation mixing, etc., but the continuous method is preferable from the viewpoint of monodispersion and small particle size.

  Examples of the continuous mixing device include a dynamic mixing device having a stirrer inside the mixing device and a static mixing device without a stirrer, but a static mixing device having no extra dead space inside the mixing device is preferable. . In particular, a manufacturing apparatus having a static mixing device in which the mixing discharge pipe and the supply pipe are connected so that the axis of the mixing discharge pipe and the axes of the plurality of supply pipes intersect at one place and the axes coincide at the intersection. It is preferable to mix simultaneously by using.

  In the case of an agitator using a normal mixing kettle, the generated nuclei circulate and return, so that nuclei cannot be generated in a uniform state during the nucleation time. The addition liquid is controlled to a desired amount to the mixing apparatus, and the generated nuclei are immediately discharged through the discharge pipe, thereby enabling nucleation in a steady state. Here, the static mixing device refers to mixing a plurality of reaction solutions without intentionally performing physical stirring by the stirring device during an initial period in which the plurality of solutions contact and mix with each other for the first time. Refers to the device to be used. Further, the desired amount to be added to the static mixing device is an amount at which mixing is performed in a turbulent state. Turbulent flow refers to turbulence in which each particle of fluid has a partial velocity in directions other than the main flow, and its size is constantly changed.

  An aqueous solution or suspension of an organic acid and an alkali metal salt of an organic acid and an aqueous metal salt solution containing a metal ion capable of exchange reaction with the alkali metal of the organic acid alkali metal salt are simultaneously metered in accordance with the design recipe. It is desirable. Examples of the continuous liquid weighing method include a method for detecting the volume and a method for detecting the mass. A mass detection method that is not affected by the volume change due to the temperature variation of the liquid is preferable.

  Here, the simultaneous metering refers to an aqueous solution or suspension of an organic acid and an alkali metal salt of an organic acid, and an aqueous metal salt solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt. At least 50% or more is metered at the same time, and the co-metered amount is preferably 80% or more, more preferably 90% or more.

  The conceptual diagram of the preparation apparatus of the organic acid metal salt for implementing this invention is shown in FIGS. Here, description will be given mainly with reference to FIG.

  One of the silver ion-containing solution and the organic acid alkali metal salt solution is prepared in the preparation tank for additive liquid 1, and the other is prepared in the preparation tank for additive liquid 2.

  Additive liquids 1 and 2 prepared in the respective preparation tanks 11 and 12 in FIG. 1 are quantitatively supplied to the static mixing device 17 by pumps 13 and 14 to produce organic acid silver salt particles. In the present invention, the silver ion-containing solution and the organic acid alkali metal salt solution or suspension are mixed under the condition that the temperature in the static mixing apparatus is 35 ° C. or higher and 70 ° C. or lower. Preferably 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. This is because if the mixing temperature is too low, the reaction in the static mixing device is suppressed, and if the temperature is too high, the side reaction is promoted.

  The cooling for adjusting the viscosity of the aqueous solution or suspension of the organic acid and the organic acid alkali metal salt may be performed by any method as long as the desired cooling rate can be secured. Specific methods include a method of cooling the refrigerant through the jacket of the kettle while stirring the liquid in a kettle with a stirrer, a method of cooling the liquid by flowing it through a heat exchanger, or a combination of both. In terms of more efficient cooling, it is preferable to use online heat exchangers (24 and 39) as shown in FIGS.

  Specific examples of the heat exchanger include plate type, shell & tube type, double tube type, double tube + static mixer type, etc., preferably double tube type or double tube + static mixer type. is there.

  In the present invention, the aqueous solution or suspension of the organic acid and organic acid alkali metal salt is from 1 ° C./min to 1000 ° C./min from a high temperature (70 ° C. to 100 ° C.) to a low temperature (0 ° C. to 60 ° C.). It is preferable to prepare under the conditions of cooling at the following cooling rate. Furthermore, the cooling rate is more preferably 10 ° C./min or more and 1000 ° C./min or less.

  On the other hand, in order to further stabilize the production of the organic acid silver salt particles of the present invention, the amount of liquid to be supplied is detected by the flow rate detector 15 and the detection result is fed back to the pump 13 for additive solution 1 to control the supply flow rate. Similarly, the amount of liquid to be supplied is detected by the flow rate detector 16, and the detection result is fed back to the pump 2 for additive liquid 2 to control the supply flow rate. By controlling the flow rates of the two liquids used for the reaction simultaneously, a constant reaction field can be maintained and side reactions can be suppressed. Specific examples of the flow rate detection means include a flow meter or pressure gauge provided between the quantitative supply device and the static mixer, and a mass detection means provided in the preparation tank.

  Although not shown in FIGS. 1 to 3, it is preferable that the suspension containing the generated particles after mixing is continuously cooled by a heat exchanger to suppress particle growth. Thereby, the particle growth by Ostwald ripening can be suppressed.

  As for the inner diameter of the mixed discharge pipe after mixing by the static mixing apparatus, if the inner diameter of the pipe is smaller than 1 mm, the liquid feeding speed is low, mixing is not sufficient, and productivity is lowered. When the inner diameter of the tube exceeds 100 mm, it becomes difficult to perform uniform mixing.

  In the manufacturing apparatus according to the present invention, the mixing discharge pipe and the plurality of supply pipe axes intersect at one place, and the mixing discharge pipe and the supply pipe are connected so that the axes coincide at the intersection. In this case, the axis of the mixed discharge pipe and the axes of the plurality of supply pipes intersect at one place, and the axes coincide at the intersection point are the axes of all the pipes. Are not limited to a desirable mode in which the axes are gathered at one place and the axes coincide at one intersection, but include a mode in which there is an axis misalignment within 10% of the inner diameter of the thickest pipe among the pipes to be connected. Within this range, the effects of the present invention can be obtained.

  The amount of silver in the organic acid silver salt particles at the time when the organic acid silver salt nuclei are generated by mixing the silver nitrate solution and the organic acid alkali metal salt solution or suspension greatly affects the monodispersity of the particles. Therefore, it is preferable that the silver amount is 0.0001 mol / L to 0.01 mol / L or less when the silver nitrate solution and the organic acid alkali metal salt solution or suspension are mixed to generate the organic acid 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 pump used for mixing the silver nitrate solution and the organic acid alkali metal salt to generate the nucleus of the organic acid silver salt has no pulsating flow. When the pulsation of the pump is large, the degree of supersaturation in the portion where both the silver nitrate solution and the organic acid alkali metal salt are mixed fluctuates greatly periodically, resulting in non-uniform nuclei. This significantly impairs the monodispersity of the produced particles. For this reason, the pulsating flow of the pump to be used is preferably ± 2.0% or less of the average flow rate, more preferably 1.0% or less, and particularly preferably 0.5%.

  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.

  In the present invention, the mixing in the reaction apparatus is not particularly limited, but it is preferably a substantially turbulent flow in the sense 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.

  Generally, when Re <2100, laminar flow, 2100 <Re <4000 is referred to as a transition region, and when Re> 4000, it is referred to as turbulent flow. In the present invention, substantially turbulent flow means Re> 4000, preferably Re> 5000, and more preferably Re> 10000.

  In particular, the Reynolds number in the mixed discharge pipe is preferably 4,000 or more as described above from the viewpoint of monodispersity of the particle diameter of the organic acid silver salt particles, fog, 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 said mixed discharge pipe 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 organic acid silver salt production apparatus according to the present invention, organic acid silver salt particles having an organic acid silver salt particle having a sphere equivalent average diameter of 0.1 μm to 0.6 μm have a coefficient of variation of the sphere equivalent average diameter of 25. %, And when the organic acid silver salt particles according to the present invention are used in a silver salt photothermographic dry imaging material, the occurrence of fogging can be reduced.

(Organic acid silver salt particles)
Hereinafter, as a typical example of the organic acid metal salt according to the present invention, organic acid silver salt particles, particularly fatty acid silver salt particles, a production method thereof, and the like will be described in more detail.

  The organic acid silver salt particles according to the present invention (hereinafter also referred to as “organic acid silver salt” or simply “organic silver salt”) can be used for various purposes and applications. Can be used as a non-photosensitive organic acid silver salt that can function as a supply source for supplying silver ions for forming a silver image.

  That is, when used in a silver salt photothermographic dry imaging material, the organic acid 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 thermal development process heated to 80 ° C. or higher in the presence of the silver salt, the silver salt can be used as a silver salt that functions as a silver ion supply source and contributes to silver image formation.

  As such non-photosensitive organic acid silver salts, conventionally, silver salts of organic compounds having various chemical structures are known. For example, paragraphs “0048” to “0049” of JP-A No. 10-62899 are known. European Patent Application Publication No. 803,764A1, page 18, line 24 to page 19, line 37, European Patent Application Publication No. 962,812A1, specification of JP-A-11-349591, JP2000 No. -7683, No. 2000-72711, No. 2002-23301, No. 2002-23303, No. 2002-49119, No. 196446, European Patent Application No. 1246001A1, European Patent Application Japanese Patent Publication No. 1258775A1, Japanese Patent Application Laid-Open No. 2003-140290, Japanese Patent Application Laid-Open No. 2003-195445 Same 2003-295378, JP same 2003-295379, JP same 2003-295380 JP, are described in the 2003-295381 Patent Publication.

  In the present invention, various known organic acid silver salts can be used. However, it is preferable to use a silver salt of a long chain aliphatic carboxylic acid having 10 to 30, preferably 12 to 26 carbon atoms. Examples of suitable silver salts include the following.

  Examples thereof include silver salts such as behenic acid, stearic acid, arachidic acid, palmitic acid, and lauric acid, and preferable silver salts include silver behenate, silver arachidate, and silver stearate.

  In the present invention, it is preferable that two or more kinds of aliphatic carboxylic acid silver salts are mixed in order to improve developability and form a silver image having a high density and a high contrast. It is preferable to prepare by mixing a silver ion solution with an aromatic carboxylic acid mixture.

  On the other hand, from the viewpoint of the storage stability of the image after development, the melting point of the aliphatic carboxylic acid which is a raw material for the aliphatic carboxylate silver is 50 ° C or higher, preferably 60 ° C or higher. The content ratio 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.

  The aliphatic carboxylic acid silver salt is obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and is described in Japanese Patent Application Laid-Open No. 9-127643. The controlled double jet method as described above is preferably used. For example, an alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate), and then a controlled double jet. According to the method, the soap and silver nitrate are mixed to produce an aliphatic carboxylic acid silver salt crystal. At that time, seed crystal grains of silver aliphatic carboxylate, silver halide grains, and the like may be mixed.

[Types of alkali metal compounds]
Examples of the types of alkali metal compounds that can be used in the production of the aliphatic carboxylic acid silver salt according to the present invention include sodium hydroxide, potassium hydroxide, and lithium hydroxide. 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. As a combination ratio, it is preferable that the molar ratio of both of the hydroxides is in the range of 10:90 to 75:25. 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 in a good state.

  In addition, when preparing an aliphatic carboxylate silver salt in the presence of silver halide grains having an average grain size of 0.050 μm or less, the alkali metal of the alkali metal compound has a higher potassium ratio. It is preferable because dissolution of silver particles and Ostwald ripening are prevented. Moreover, the size of fatty acid silver salt particle | grains can be made small, so that the ratio of potassium salt is high. A preferable ratio of the potassium salt is 50 to 100% with respect to the total alkali metal compound used in the step of producing aliphatic silver carboxylate. The concentration of the alkali metal compound is preferably 0.1 to 0.3 mol / 1000 ml.

[High silver conversion rate silver salt particles]
The emulsion containing the aliphatic carboxylic acid silver salt grains according to the present invention is a mixture of a free aliphatic carboxylic acid and an aliphatic carboxylic acid silver salt that do not form a silver salt, but the former ratio is relative to the latter. Low is preferable from the viewpoint of image storage stability and the like. That is, the emulsion according to the present invention preferably contains 3 to 10 mol% of an aliphatic carboxylic acid with respect to the aliphatic carboxylic acid silver salt grains. Particularly preferably, the content is 4 to 8 mol%.

  Specifically, by determining the total aliphatic carboxylic acid amount and the free aliphatic carboxylic acid amount by the following method, respectively, the aliphatic carboxylic acid silver salt and the free aliphatic carboxylic acid amount and the respective ratios or The ratio of free fatty acid to total aliphatic carboxylic acid is 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 that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a 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.

  In the present specification, the scaly 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 using 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 the aliphatic carboxylate silver, 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 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 term “monodispersed” as used herein means that the coefficient of variation of the particle diameter determined 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 determine 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) directly An image is 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, and an average particle size can be calculated. .

  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 a very thin collodion or form bar. More preferably, the carbon film is formed on a rock salt substrate and dissolved and removed. 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 the above-mentioned shape is not particularly limited. For example, the mixed state at the time of forming the organic acid alkali metal salt soap or the mixed state at the time of adding silver nitrate to the soap. It is effective to keep it good, and to set the ratio of the organic acid to the soap and the ratio of the silver nitrate that reacts with the soap optimally.

  In the present invention, tabular aliphatic carboxylic acid silver salt particles (aliphatic carboxylic acid having an average equivalent circle diameter of 0.05 μm to 0.8 μm and an average thickness of 0.005 μm to 0.07 μm) The acid silver salt particles) are preferably pre-dispersed with a binder, a surfactant or the like, if necessary, and then dispersed and ground 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 rotary centrifugal radiation type stirrer (dissolver), or a high speed rotary shear type stirrer (homomixer) can be used.

  Further, as the media disperser, for example, a rolling mill such as a ball mill, a planetary ball mill, a vibrating ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills can be used, and as a high-pressure homogenizer Various types can be used, such as a type that collides with a wall, a plug, etc., a type in which liquids are collided with each other at high speed, and a type through which a thin orifice is 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 for dispersing the tabular aliphatic carboxylate silver salt particles according to the present invention, examples of the material of the member in contact with the aliphatic carboxylate silver salt particles include zirconia, alumina, silicon nitride, and boron nitride. It is preferable to use ceramics such as the above or diamond, and it is 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, 29 to 100 MPa, and the number of operations is preferably 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, it is preferable that the non-photosensitive aliphatic carboxylic acid silver salt particles are 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.

  In the present invention, the compound that functions as a crystal growth inhibitor or dispersant for the aliphatic carboxylate silver particles refers to a silver aliphatic carboxylate under the conditions in which the compound coexists in the production process of the aliphatic carboxylate particles. A compound having a function and an effect of reducing the particle size or monodispersing than when it is produced under conditions that do not coexist. 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. In addition, aliphatic unsaturated carboxylic acids such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, moloctic acid, eicosenoic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, and ceracolonic acid It is done. A preferable addition amount is 0.5 to 10 mol% of the silver aliphatic carboxylate.

  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.

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

  As the photosensitive silver halide grains according to the present invention, silver halide grains conventionally disclosed in many patent publications relating to silver salt photothermographic dry imaging materials can be used. Specific examples of silver halide grains that can be preferably used include, for example, the manufacturing method described in JP-A-2003-270755, chemical properties such as halogen composition, physical properties such as shape, etc. Silver halide grains produced in the same manner.

  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 smaller than 0.02 μm are excluded from the measurement target, 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, cubic, octahedral, 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. Moreover, 95% or more of these substitution rates are preferable, More preferably, it is 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 that increases hydrophobicity by substituting the amino group and / or carboxyl group of gelatin.

  In addition, 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 coated by being 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 soluble in both water and organic solvent may be any of natural polymer, synthetic polymer and copolymer. 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 polymer according to the present invention includes 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 methacrylate 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 (epoxide), poly (car Sulfonates), poly (vinyl acetate), poly (olefins), cellulose esters, poly (amides), and the like.

  Several types 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.

  The nonionic active agent is well known for the phenomenon of cloud point, but it has a property that it becomes lipophilic with increasing temperature and becomes soluble in organic solvents, and is hydrophilic, that is, soluble in water when the temperature decreases. Is also included in the polymer. It is sufficient that micelles are formed and uniformly emulsified even if they are not completely dissolved.

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

  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, though it may be adjusted by adjusting the conditions such as pH as described above, or may not be adjusted. And an organic solvent having a solubility of 5% by mass or more (25 ° C.) in methyl ethyl ketone is preferable.

  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 silver salt photothermographic dry imaging material of the present invention, for the purpose of preventing aggregation and uniform dispersion of the above-mentioned silver halide grains, a surfactant, in particular a non-ion, is added to the silver halide grain dispersion. It is also preferable to contain a functional surfactant.

  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 and the like related to silver salt photothermographic dry imaging materials. For example, compounds or gold ions that release chalcogens such as sulfur, selenium, tellurium, etc. by the methods described in JP-A-2000-270755, JP-A-2001-249428, and JP-A-2001-249426. By using a noble metal compound that releases a noble metal ion, a chemical sensitization center capable of capturing electrons or holes (holes) generated by photoexcitation of photosensitive silver halide grains or spectral sensitizing dyes on the grains ( Chemical sensitization nuclei). 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 heat development process, an oxidant capable of destroying the chemical sensitization center (chemical sensitization nucleus) by an oxidation reaction at the time of heat 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. Techniques using dyes, oxonol dyes, hemioxonol dyes and the like as spectral sensitizing dyes can be used.

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

  The emulsion containing photosensitive silver halide grains and aliphatic carboxylic acid silver salt grains used in the silver salt photothermographic dry imaging material of the present invention is a dye having no spectral sensitizing action itself or a sensitizing dye. A substance that does not substantially absorb visible light and exhibits a supersensitization effect may be included 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 preferred 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 sensitizing effect is substantially lost 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, use a spectral sensitizing dye that is easily detached from the silver halide grains by heat during thermal development or / and destroy the spectral sensitizing dye 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. However, it is more preferable in that a photothermographic material having a high density and excellent light-irradiation image storage stability can be obtained. 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 such as 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 diagnostic observation result. Here, the cool image tone means 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 with a black image, but 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.

Next, an example of a method for creating the above-described linear regression line, that is, a method for measuring u ^* , v ^* and a ^* , b ^{* in} the CIE1976 color space will be described.

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 thus produced is measured with a spectrocolorimeter (Minolta Co., Ltd .: CM-3600d or the like), 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 characteristics 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 toning agents, color tone using couplers disclosed in JP-A-11-288057, European Patent No. 1,134,611A2, etc. and leuco dyes 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 silver salt photothermographic 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 being excessively reddish at the above high density portion, it is preferable to use a leuco dye that develops yellow and cyan colors and to 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 preferable 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 that the color is developed so as to have 0.03 or more and 0.10 or less.

(binder)
In the silver salt photothermographic 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 can carry organic acid silver salt, silver halide grains, a reducing agent, and other components. Suitable binders are transparent or translucent and generally colorless. And natural polymers, synthetic polymers, copolymers, 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.

  For non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters which are polymers with higher softening temperatures, especially polymers such as triacetyl cellulose and cellulose acetate butyrate preferable. 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 acid silver salt in the photosensitive layer (image forming layer), the ratio of the binder to the organic acid silver salt is preferably 15: 1 to 1: 2 (mass ratio), particularly A range of 8: 1 to 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. Incidentally, 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 may contain a cross-linking agent capable of connecting the binders according to the present invention by cross-linking. By using a crosslinking agent for the binder, it is known that filming is improved and development unevenness is reduced, but there is also an effect of suppressing fogging during storage and suppressing 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.

  In addition, the adduct of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion and prevent layer peeling, image shift and bubble generation. Such isocyanate may be placed in 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, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer 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 good result can be obtained even if the compound has 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 the photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc., and one of these layers Or it can add to 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. As used herein, the silver saving agent 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. This silver saving agent can be present in the photosensitive layer, the non-photosensitive layer, or both. 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.

  Particularly preferred silver saving agents as the silver saving agent according to the present invention 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 silver salt photothermographic 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 silver salt photothermographic dry imaging material containing the thermal solvent. 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, carboxy group, amino group, amide group, sulfonamide group, phosphoric acid amide group, cyano group, imide, ureido, sulfoxide, sulfone, phosphine, phosphine oxide or 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 carbon atoms, particularly preferably 1 to 25 carbon atoms such as 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. Phenyl, naphthyl, etc.), heterocyclic groups (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 those described in “0015” of JP-A No. 2004-21068. The reason why development activity is achieved by using a thermal solvent is that the thermal solvent melts near the development temperature, so that it is compatible with substances involved in development, and a reaction at a lower temperature than when no thermal 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 to an external environment such as image storage stability, which is 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, and 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 ultrasonic waves 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)
In any constituent layer of the silver salt photothermographic dry imaging material of the present invention, an antifoggant for preventing fogging during storage before heat development, and an image deterioration after heat development are prevented. It is preferable to contain an image stabilizer.

  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 reducing agents 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. Moreover, it is preferable that the compound which can carry out the oxidative bleaching of the silver atom thru | or metal silver (silver cluster) produced | generated at the time of preservation | save of a raw film or an image 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 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 silver salt photothermographic dry imaging material of the present invention forms a photographic image by heat development processing, and a toning agent (toner) for adjusting the color tone of silver as required is usually contained in an (organic) binder matrix. It is preferably contained in a dispersed state.

  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 (eg, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide); mercaptans (eg, 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 anhydrides thereof Products (eg, phthalic acid, 4-methylphthalic acid, 4 The combination and the like with at least one compound selected from nitrophthalic 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, carboxylic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), 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 phosphoric acid 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. aromatic compound or a compound obtained by addition reaction and condensation reaction between the hetero compound having 3 or 4 (part R _f of alkanols compounds), further for example, introducing an anionic group (a) with sulfuric acid esterification, etc. 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 for 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 dissolved and added 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 having a size of 1 μm or less can be added after being dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion. 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 silver salt photothermographic dry imaging material is used for various photosensitive devices in contact with the photothermographic dry imaging material during the winding, rewinding, and transporting of the photosensitive material in the manufacturing process such as coating, drying, and processing. Often undesirably affected by contact between the photothermographic dry imaging materials, such as between the layer 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 silver salt photothermographic dry imaging material of the present invention, in order to prevent scratches on the surface and deterioration of transportability, any one of the constituent layers of the material, particularly on the support. It is preferable that the outermost layer contains a lubricant, a matting agent or the like to adjust the physical properties of the surface of the material.

  In the silver salt photothermographic 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 these organic solid lubricant particles are dispersed by a polymer dispersant. This is what it is. 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. Examples thereof include formed particles.

  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 silver salt photothermographic dry imaging material of the present invention, the organic solid lubricant particles are particularly preferably a compound represented by the following general formula (OL1).

General formula (OL1)
_{(R 1) p -X 1 -L} -X 2 - (R 2) q
In the formula, each of R ₁ and R ₂ is 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 different even in the same 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 silver salt photothermographic 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 of light transmitted through the photosensitive layer or the wavelength distribution. It is preferable to contain a dye or pigment in the layer.

  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 silver salt photothermographic dry imaging material of the present invention is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (this specification) Used as a thiopyrylium squarylium dye) and a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), or a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. It is preferable to do.

  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 silver salt photothermographic dry imaging material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (aluminum, etc.), etc. For handling, a material that can be processed into a flexible sheet or roll is preferable. 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 silver salt photothermographic 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, it can be used SNS10M, SN-100P, SN- 100D, the FSS10M like.

(Component layer)
The silver salt photothermographic dry imaging material of the present invention has a photosensitive layer which is at least one image forming layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. For example, a protective layer is preferably provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and the opposite surface of the support is “sticking” between the photosensitive materials or in the photosensitive material roll. In order to prevent “,” a backcoat layer is provided.

  As a binder used in these protective layers and backcoat layers, a glass transition point (Tg) is higher than that of the photosensitive layer, and a polymer which is not easily scratched or deformed, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propio. Polymers such as nates are selected from the binders described above.

  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.

(Application of component layers)
The silver salt photothermographic dry imaging material of the present invention is formed by preparing a coating solution in which the above-described constituent layers are dissolved or dispersed in a solvent, and applying a plurality of these coating solutions simultaneously, followed by heat treatment. It is preferable. 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 silver salt photothermographic dry imaging material, but is 0.3 g / m ² or more for medical purposes. preferably .5g / m ² or less, 0.5 g / m ² or more, 1.5 g / m ² or less is more preferable. Among the applied silver amounts, those derived from silver halide preferably account for 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 silver salt photothermographic 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. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

(Odor and pollution prevention technology)
Technology for reducing / preventing odors 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 silver salt photothermographic dry imaging material of the present invention A preferred embodiment will be described.

  In the silver salt photothermographic dry imaging material of the present invention, the protective layer preferably has a function of preventing contaminants generated during the heat development from volatilizing or adhering to the outside of 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, 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%.

  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). Can do. 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)
In the case of storing the silver salt photothermographic dry imaging material of the present invention, in order to prevent density change and fog generation over time, or to improve curling, curling, etc., oxygen permeability and / or moisture permeability It is preferable to package with a low packaging material. 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. humidity 90% RH · day or less, still more preferably not more than 0.001g / m ² · 40 ℃ · RH 90% RH · day.

  Specific examples of packaging materials for silver salt photothermographic dry imaging materials include, for example, JP-A-8-254793, JP-A-2000-206653, JP-A-2000-235241, JP-A-2002-062625, JP-A-2003-2003. 015261, JP 2003-057790, JP 2003-084397, JP 2003-098648, JP 2003-098635, JP 2003-107635, JP 2003-131337, JP 2003-146330. No., JP-A-2003-226439, JP-A-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 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)
Regarding the exposure used for the exposure of the silver salt photothermographic dry imaging material of the present invention or the exposure in the image forming method of the present invention, there are various light sources, exposure times, etc. suitable for obtaining a desired appropriate image. The following conditions can be adopted.

  The silver salt photothermographic 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 Infrared semiconductor lasers (780 nm, 820 nm) are more preferably used from the standpoint of being transparent.

In particular, the photothermographic 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 refers to 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 a required optical density is reduced, 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 the laser preferably used in 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. In addition, a semiconductor laser and a second harmonic generation element can be used. Further, 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 to purple light emitting high-power semiconductor laser is Nichia's NLHV 3000E 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 scanning 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 a vertical multiplex, methods such as using return light by combining and applying high-frequency superposition are 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 laser light on the photoconductor in the image writing means of a laser printer or digital copying machine is for one line from the image formation position of one laser light for the purpose of writing an image by a plurality of lines in one scan. The next laser beam is imaged by shifting. Specifically, the two light beams are close to each other on the image plane in the sub-scanning direction at intervals of the 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 ₂ lasers, semiconductor lasers such as GaSb lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner, but among these, semiconductors with a wavelength of 600-1200 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 material exposure surface when scanned with a silver salt photothermographic dry imaging material is generally 5 to 75 μm as a short axis diameter, and a long axis. The diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photothermographic dry imaging material depending on the sensitivity and laser power at the lasing wavelength inherent to the silver salt photothermographic dry imaging material. .

(Laser imager and development conditions)
The laser imager (heat development processing apparatus) referred to in the present invention has a structure that is uniform and stable over the entire surface of a film supply unit represented by a film tray, a laser image recording unit, and a silver salt photothermographic dry imaging material. A heat developing unit for supplying heat and a conveying unit for discharging the photothermographic dry imaging material image-formed by heat development through laser recording from the film supply unit 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 the position where the light from the exposure light source is applied to the silver salt photothermographic dry imaging material, and the development part refers to the position where the photothermographic material is heated for the first time for thermal development. Say.

  In addition, the conveyance speed in the heat development part of a silver salt photothermographic 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 silver salt photothermographic dry imaging materials vary depending on the equipment, equipment, or means used, but typically heat the photothermographic dry imaging material imagewise exposed at a suitable high temperature. The development is performed. 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 silver salt photothermographic dry imaging material of the present invention is preferably performed by bringing the surface on the side having the protective layer into contact with the heating means, for uniform heating, It is preferable from the viewpoints of thermal efficiency, workability, and the like, and it is preferable that the surface on the side having the protective layer is conveyed while being in contact with the heat roller, and is developed by heat treatment.

  In the silver salt photothermographic dry imaging material of the present invention, an image obtained by heat development at a heating temperature of 123 ° C. and a development time of 12 seconds has a unit length of diffusion density (Y axis) and common log exposure (X axis). In the characteristic curves shown on the equal orthogonal coordinates, the average gradation of 0.25 to 2.5 is preferably 2.0 to 4.0 in terms of optical density with diffused light. By using such gradations, 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 acid metal salt 1-1)
An organic acid metal salt 1-1 was prepared using an apparatus as shown in FIG. In the preparation tank 11, 1170 g of an aqueous solution in which 5.0 mol of KOH was dissolved while stirring 1.5 kg of stearic acid (NAA-180 manufactured by Nippon Oil & Fats Co., Ltd., neutralization number 196.7) and 28 kg of pure water at 80 ° C. After the addition, the mixture was reacted for 60 minutes to obtain a potassium stearate solution. Finally, additional pure water was added to make the total volume 31.4L. Next, 31.4 L of an aqueous solution in which 5.0 mol of zinc nitrate was dissolved was prepared in the preparation tank 12 and kept at 40 ° C. The above-mentioned potassium stearate solution and zinc nitrate aqueous solution are added at a constant flow rate of 10 L / min to the static mixing device (inner diameter 5 mm of the supply pipe and discharge pipe) shown in FIG. did. Thereafter, the solution was sent to a centrifuge, and pure water was added, and washing with pure water was continued until the conductivity of the drainage reached 30 μS / cm. After completion of washing with water, centrifugal dehydration was performed to remove excess moisture, and then drying was performed with a hot air circulating dryer at 40 ° C. until there was no mass loss to obtain a dried powder of organic acid metal salt.

(Preparation of organic acid metal salt 1-2 to 1-4)
Organic acid metal salts 1-2 to 1-4 were prepared in the same manner as organic acid metal salt 1-1 except that stearic acid, KOH, and zinc nitrate were changed to Table 1.

(Evaluation of organic acid metal salts)
The morphology of the organometallic salts 1-1 to 1-4 was evaluated by electron microscope photography. The results are shown in Table 2. Moreover, the result of having measured the viscosity of the potassium stearate solution and the zinc nitrate aqueous solution with a vibration type viscometer (SV-10 manufactured by A & D Corporation) is also shown.

  From Table 2, it can be seen that the organic acid metal salt particles according to the present invention have a small particle size and a small variation coefficient of the particle size.

Example 2
(Preparation of organic acid metal salt 2-1)
An organic acid metal salt 2-1 was prepared using an apparatus as shown in FIG. In the preparation tank 11, 974 g of an aqueous solution in which 4.16 mol of KOH was dissolved while stirring 1.5 kg of behenic acid (NAA-222S manufactured by NOF Corporation, neutralization number 163.7) and 28 kg of pure water at 80 ° C. After the addition, the mixture was reacted for 60 minutes to obtain a potassium behenate solution. Finally, additional pure water was added to make the total volume 31.2L. Next, 31.2 L of an aqueous solution in which 4.16 mol of silver nitrate was dissolved was prepared in the preparation tank 12 and kept at 40 ° C. The above-mentioned potassium stearate solution and zinc nitrate aqueous solution are added at a constant flow rate of 10 L / min to the static mixing device (inner diameter 5 mm of the supply pipe and discharge pipe) shown in FIG. did. Thereafter, the solution was sent to a centrifuge, and pure water was added, and washing with pure water was continued until the conductivity of the drainage reached 30 μS / cm. After completion of washing with water, centrifugal dehydration was performed to remove excess moisture, and then drying was performed with a hot air circulating dryer at 40 ° C. until there was no mass loss to obtain a dried powder of organic acid metal salt.

(Preparation of organic acid metal salt 2-2)
An organic acid metal salt 2-2 was prepared using an apparatus as shown in FIG. In the preparation tank 21, 974 g of an aqueous solution in which 4.16 mol of KOH was dissolved while stirring 1.5 kg of behenic acid (NAA-222S manufactured by NOF Corporation, neutralization number 163.7) and 28 kg of pure water at 80 ° C. After the addition, the mixture was reacted for 60 minutes to obtain a potassium behenate solution. Finally, additional pure water was added to make the total volume 31.2L. Next, 31.2 L of an aqueous solution in which 4.16 mol of silver nitrate was dissolved was prepared in the preparation tank 26 and kept at 60 ° C. The potassium behenate solution prepared in the tank 21 is sent to the heat exchanger 24 using the pump 22, the temperature is cooled from 80 ° C. to 60 ° C. at a cooling rate of 0.5 ° C./min, and the preparation tank 25 is heated to 60 ° C. Stocked at. A potassium behenate solution and a zinc nitrate aqueous solution were added at a constant flow rate of 10 L / min to a static mixing apparatus (inner diameter 5 mm of the supply pipe and the discharge pipe) indicated by 27 in FIG. Thereafter, the solution was sent to a centrifuge, and pure water was added, and washing with pure water was continued until the conductivity of the drainage reached 30 μS / cm. After completion of washing with water, centrifugal dehydration was performed to remove excess moisture, and then drying was performed with a hot air circulating dryer at 40 ° C. until there was no mass loss to obtain a dried powder of organic acid metal salt.

(Preparation of organic acid metal salts 2-3 to 2-5)
Organic acid metal salts 2-3 to 2-5 were prepared in the same manner as organic acid metal salt 2-2 except that the cooling rate of the potassium behenate solution was changed to Table 3.

(Preparation of organic acid metal salt 2-6)
An organic acid metal salt 2-6 was prepared using an apparatus as shown in FIG. In the preparation tank 31, 974 g of an aqueous solution in which 4.16 mol of KOH was dissolved while stirring 1.5 kg of behenic acid (NAA-222S manufactured by NOF Corporation, neutralization number 163.7) and 28 kg of pure water at 80 ° C. After the addition, the mixture was reacted for 60 minutes to obtain a potassium behenate solution. Finally, additional pure water was added to make the total volume 31.2L. Next, 31.2 L of an aqueous solution in which 4.16 mol of silver nitrate was dissolved was prepared in the preparation tank 32 and kept at 60 ° C. A potassium behenate solution and a zinc nitrate aqueous solution were added at a constant flow rate of 10 L / min to a static mixing apparatus (inner diameter 5 mm of the supply pipe and the discharge pipe) indicated by 37 in FIG. At that time, the potassium behenate solution was added while continuously cooling from 80 ° C. to 60 ° C. through the heat exchanger 39. Thereafter, the solution was sent to a centrifuge, and pure water was added, and washing with pure water was continued until the conductivity of the drainage reached 30 μS / cm. After completion of washing with water, centrifugal dehydration was performed to remove excess moisture, and then drying was performed with a hot air circulating dryer at 40 ° C. until there was no mass loss to obtain a dried powder of organic acid metal salt.

(Evaluation of organic acid metal salt particles)
The forms of the organometallic salts 2-1 to 2-6 were evaluated by electron microscope photography. The results are shown in Table 4. Moreover, the result of having measured the viscosity of the potassium behenate solution and silver nitrate aqueous solution at 60 degreeC with a vibration type viscometer (SV-10 by A & D Co., Ltd.) and the temperature after mixing are also shown.

  Table 4 shows that the organic acid metal salt particles according to the present invention have a small particle size and a small coefficient of variation in particle size.

Example 3
(Preparation of silver halide grain emulsion A)
Silver halide grain emulsion A was prepared by the following procedure.

(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 was 1161 g per mole of silver to obtain silver halide emulsion A.

  The silver halide grains in the silver halide emulsion 1 prepared as described above have a monodispersed cubic iodine odor with an average sphere equivalent diameter of 0.045 μm, a sphere equivalent diameter variation coefficient of 12%, and a [100] face ratio of 92%. It was silver halide 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. Further, 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 grain emulsion 1 was 61% by mass in terms of silver amount.

(Synthesis of polymer B for dispersing silver halide grains)
A 0.5 liter four-necked separable flask was equipped with a dropping device, a thermometer, a nitrogen gas introduction 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 5 ( Unit g) was charged and heated to 80 ° C. Further, a solution obtained by dissolving NIPAM (unit: g) shown in Table 5 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 then a polymer B 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 MEK-dispersed silver halide grain emulsion)
[MEK-dispersed silver halide grain emulsion 1]
The polymer B solution (33 g) was dropped into 10 times the amount of pure water, precipitated, filtered, and washed with water 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 the mixture was further stirred for 30 minutes. Thereafter, the temperature was lowered to 35 ° C. over 30 minutes, and then 600 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 grain 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 ½ 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 the same amount of methyl ethyl ketone as the concentrated one 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 organic acid silver salt dispersion)
Examples 2-1 to 2-6 were dissolved in 1300 g of methyl ethyl ketone 49 g of polyvinyl butyral (Sekisui Chemical Co., Ltd. S-REC B / BL-SHP) and stirred with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN. A preliminary dispersion was prepared by gradually adding and thoroughly mixing 500 g of the powdered organic acid metal salt prepared in 1. After the total amount of the powdered organic acid metal salt was added, the mixture was stirred at 1500 rpm for 15 minutes. Media-type disperser filled with 80% of the internal volume of 0.5 mm diameter zirconia beads (Traceram manufactured by Toray Industries, Inc.) so that the residence time in the mill is 1.2 minutes using a pump. Organic acid silver salt dispersions 1 to 6 were prepared by supplying to a DISPERMAT SL-C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 9 m / s. The solid content concentration of the obtained organic acid silver salt dispersion was about 27%.

[Preparation of underdrawn support]
Corona discharge treatment is performed on both sides of a biaxially stretched polyethylene terephthalate film with a blue dye concentration of 0.135 under the condition of 10 W / m ² · min, and the following back surface side undercoat lower layer coating solution is dried on one surface. It was coated to 0.06 μm and dried at 140 ° C. Subsequently, the following back surface side undercoat upper layer coating solution was coated to a dry film thickness of 0.2 μm and then dried at 140 ° C. On the opposite side, the following photosensitive layer side undercoat lower layer coating solution is applied so as to have a dry film thickness of 0.25 μm, and then the following photosensitive layer side undercoat upper layer coating solution is dried film thickness. After coating to 0.06 μm, it was dried at 140 ° C. These were heat-treated at 140 ° C. for 2 minutes to produce a sample with an underdrawn.

<< Back surface side undercoat lower layer coating liquid >>
Copolymer polymer latex of styrene / glycidyl methacrylate / butyl acrylate (20/20/40) (solid content 30%) 16.0 g
Copolymer polymer latex of styrene / butyl acrylate / hydroxymethyl methacrylate (25/45/30) (solid content 30%) 4.0 g
SnO ₂ sol (solid content 10%) (synthesized by the method described in JP-A-10-059720) 91 g
Surfactant A 0.5g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

<< Back surface side undercoat upper layer coating liquid >>
Modified aqueous polyester A (solid content 18%) 215.0 g
Surfactant A 0.4g
Spherical silica matting agent Seahoster KE-P50 (Nippon Shokubai Co., Ltd.) 0.3g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

<< Synthesis of Modified Aqueous Polyester A >>
In a polymerization reactor, 35.4 parts by mass of dimethyl terephthalate, 33.63 parts by mass of dimethyl isophthalate, 17.92 parts by mass of 5-sulfo-isophthalic acid dimethyl sodium salt, 62 parts by mass of ethylene glycol, calcium acetate monohydrate 0.065 parts by mass and 0.022 parts by mass of manganese acetate tetrahydrate were added, and after a transesterification reaction was performed while distilling off methanol at 170 to 220 ° C. in a nitrogen stream, 0.04 trimethyl phosphate was obtained. As a polycondensation catalyst, 0.04 part by mass of antimony trioxide and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid are added as a polycondensation catalyst, and a theoretical amount of water is distilled off at a reaction temperature of 220 to 235 ° C. Esterification was performed. Thereafter, the inside of the reaction system was further depressurized and heated for about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to obtain a modified aqueous polyester A precursor. The intrinsic viscosity of the precursor was 0.33.

  850 ml of pure water was put into a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of the precursor was gradually added while rotating the stirring blade. After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours, and heated and dissolved at this temperature for 3 hours. After completion of the heating, the mixture was cooled to room temperature over 1 hour and allowed to stand overnight to prepare a precursor solution having a solid concentration of 15% by mass.

  1900 ml of the precursor solution was placed in a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel, and the internal temperature was heated to 80 ° C. while rotating the stirring blade. Into this, 6.52 ml of a 24% aqueous solution of ammonium peroxide was added, and a monomer mixture (28.5 g of glycidyl methacrylate, 21.4 g of ethyl acrylate, 21.4 g of methyl methacrylate) was dropped over 30 minutes. The reaction was continued for another 3 hours. Then, it cooled to 30 degrees C or less, filtered, and prepared the solution of the modified aqueous polyester A whose solid content concentration is 18 mass%.

<< Coating liquid for photosensitive layer side undercoat >>
Copolymer latex of styrene / acetoacetoxyethyl methacrylate / glycidyl methacrylate / n-butyl acrylate (40/40/20 / 0.5) (solid content 30%) 70 g
Surfactant A 0.3g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

<< Photosensitive layer side undercoat upper layer coating solution >>
Modified aqueous polyester B (solid content 18%) 80.0 g
Surfactant A 0.4g
Spherical silica matting agent Seahoster KE-P50 (Nippon Shokubai Co., Ltd.) 0.3g
Distilled water was added to make 1000 ml, and a coating solution having a solid content concentration of 0.5% was obtained.

<< Synthesis of Modified Aqueous Polyester B >>
The modified aqueous polyester B was prepared in the same manner as the knitted aqueous polyester A except that the precursor solution was 1800 ml, the monomer mixture was 31 g of styrene, 31 g of acetoacetoxyethyl methacrylate, 61 g of glycidyl methacrylate, and 7.6 g of n-butyl acrylate. A solution was made.

<< Preparation of Application Samples 101-106 >>
Coating samples 101 to 106, which are silver salt photothermographic materials, were prepared according to the following procedure.

<< Preparation of surface protective layer coating liquid >>
Methyl ethyl ketone 1056g
148 g of cellulose acetate propionate (Eastman Chemical Co., CAP141-20)
6 g of polymethyl methacrylate (Rohm and Haas, Paraloid A21)
170 g of mat dispersion (average particle size of 4 μm silica with a dispersion degree of 10%, solid content concentration of 1.7%)
_{CH 2 = CHSO 2 CH 2 CH} (OH) CH 2 SO 2 CH = CH 2 3.6g
Benzimidazole 2g
C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₃ C ₉ F ₁₇ 5.4 g
LiO ₃ S—CF ₂ CF ₂ CF ₂ —SO ₃ Li 0.12 g
《Back layer》
Methyl ethyl ketone 1350g
121 g of cellulose acetate propionate (manufactured by Eastman Chemical Co., CAP482-20)
Dye-A 0.23g
Dye-B 0.62g
Fluorine-based acrylic copolymer (Daikin Industries, Ltd., Optoflon FM450) 1.21 g
Amorphous saturated copolyester (byron 240P, manufactured by Toyobo Co., Ltd.) 18.1 g
Matting agent dispersion see below C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₃ C ₉ F ₁₇ 5.21 g
LiO ₃ S—CF ₂ CF ₂ CF ₂ —SO ₃ Li 0.81 g
2 g of organic solid lubricant particles were added to 90 g of MEK in which 2 g of the polymer dispersant was dissolved. This matting agent solution was dispersed for 30 minutes with an ultrasonic disperser (manufactured by Alex Corporation, trade name: Ultrasonic Generator, frequency 25 kHz, 600 W) to obtain a mat dispersion.

Dispersant type: CAP cellulose acetate propionate (manufactured by Eastman Chemical Co., CAP482-20), PVB polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., ESREC B / BL-SHP), polyester (manufactured by Toyobo Co., Ltd.) Byron 240P)
(Preparation of photosensitive coating solutions 1, 2, 3)
890 g of methyl ethyl ketone was added to the organic acid silver salt dispersion 1 (1670 g), and the mixture was kept at 18 ° C. with stirring. 780 g of the dispersed silver halide grain emulsion 2 in MEK was added and stirred for 30 minutes. Thereafter, 12.6 g of bis (dimethylacetamide) dibromobromate (11% methanol solution) was added and stirred for 1 hour. Subsequently, 20.1 g of calcium bromide (11% methanol solution) was added and stirred for 30 minutes. Further, a stabilizer solution and an infrared sensitizing dye solution were added and stirred for 1 hour, and then the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While keeping the temperature at 13 ° C., 416 g of polyvinyl butyral resin powder (Surek Chemical Co., Ltd., S-REC B / BL-5) was added and dissolved. After confirming dissolution, 19.8 g of tetrachlorophthalic acid (13% methyl ethyl ketone solution) was added, and the following additives were added at intervals of 15 minutes while continuing stirring to obtain photosensitive coating solution 1.

In the preparation of the photosensitive coating solution 1, photosensitive coating solutions 2 to 6 were prepared in the same manner except that the organic acid silver salt dispersions 2 to 6 were used instead of the organic acid silver salt dispersion 1.
Phthalazine 12.4g
Desmodur N3300 (Mobay, aliphatic isocyanate) 17.6 g
Antifoggant solution See below Developer solution See below <Preparation of infrared sensitizing dye solution>
300 mg of infrared sensitizing dye-1, 400 mg of infrared sensitizing dye-2, 130 mg of 5-methyl-2-mercaptobenzimidazole, 21.5 g of 2-chloro-benzoic acid, 2.5 g of sensitizing dye solubilizer An infrared sensitizing dye solution was prepared by dissolving in 135 g of methyl ethyl ketone.

<Preparation of stabilizer solution>
A stabilizer solution was prepared by dissolving 0.9 g of stabilizer and 0.3 g of potassium acetate in 14 g of methanol.

<Preparation of developer solution>
120 g of developer and 9 g of 4-methylphthalic acid were dissolved in methyl ethyl ketone and finished to 1200 g to obtain a developer solution.

<Preparation of antifoggant solution>
11.6 g of tribromomethylsulfonylpyridine was dissolved in methyl ethyl ketone and finished to 180 g to obtain an antifoggant solution.

<< Preparation of Sample 101 >>
[Coating of photosensitive layer, surface protective layer, and back layer]
The photosensitive coating solution 1 is applied so that the total silver amount is 1.6 g / m ² on the subbing on the photosensitive layer side of the undercoated sample, and the wet coating amount is 23 g / m ² on it. A surface protective layer was applied as a multilayer. Subsequently, a back layer was applied on the opposite side of the photosensitive layer side undercoat so that the wet weight was 4.2 g / m ² . The drying was performed at 60 ° C. for 15 minutes. A silver salt photothermographic dry imaging material was obtained by heat treatment at 79 ° C. for 10 minutes while conveying the sample coated on both sides.

<< Production of Samples 102 to 106 >>
In preparation of the sample 101, samples 102 to 106 were prepared using the photosensitive coating liquids 2 to 6 instead of the photosensitive coating liquid 1.

<< Evaluation of silver salt photothermographic imaging materials >>
Various evaluations were performed on the manufactured samples 101 to 106 according to the following methods.

[Exposure and development processing]
Exposure by laser scanning from the photosensitive layer-coated surface side of each of the above prepared samples by an exposure machine using an exposure source with a semiconductor laser having a longitudinal multimode wavelength of 800 to 820 nm by high frequency superposition through an optical wedge. Was given. At this time, the angle between the exposure surface of the sample and the exposure laser beam was set to 75 ° to form an image. In this case, an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 °.

  Thereafter, development was performed using an automatic developing machine having a heat drum and a cooling zone so that the protective layer of the sample and the drum surface were in contact with each other. At that time, exposure and development were performed in a room adjusted to 23 ° C. and 50% RH.

[Evaluation of fog density and humidity dependency]
The density of the obtained silver image composed of wedge gradations was measured with a densitometer, and a characteristic curve consisting of the logarithm (Log E) of the silver image density (D) on the vertical axis and the exposure amount (E) on the horizontal axis was created. . In this characteristic curve, the minimum density (fog density) and the fog density when exposure and development were performed in the same manner as described above after conditioning for 3 days in an environment of 23 ° C. and 80% RH, were dependent on humidity. The evaluation is shown in Table 6.

  As is apparent from the results in Table 6, it can be seen that the silver salt photothermographic imaging material of the present invention has a lower fog and less influence on humidity, and an appropriate output image as a diagnostic image can be obtained.

An example of an organic acid metal salt production device having a static mixing device An example of an organic acid metal salt production device having a static mixing device and a heat exchanger An example of an organic acid metal salt production device having a static mixing device and a heat exchanger

Explanation of symbols

11, 21, 25, 31 Additive liquid 1 preparation tank 12, 26, 32 Additive liquid 2 preparation tank 15, 23, 35 Additive liquid 1 flow detector 13, 22, 33 Additive liquid 1 pump 16, 36 Addition Liquid 2 flow rate detector 14, 34 Additive liquid 2 pump 17, 27, 37 Static mixing device 24, 39 Heat exchanger 18, 28, 38 Product liquid storage tank

Claims (9)

Production of organic acid metal salt particles in which an aqueous solution or suspension of an organic acid and an alkali metal salt of an organic acid and a metal salt aqueous solution containing a metal ion capable of exchange reaction with the alkali metal of the organic acid alkali metal salt are simultaneously metered and mixed. In the method, an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt having a viscosity of 1 mPa · s to 10 mPa · s and an alkali metal of the organic acid alkali metal salt having a viscosity of 1 mPa · s to 10 mPa · s. A method of producing organic acid metal salt particles, comprising simultaneously metering and mixing a metal salt aqueous solution containing a metal ion capable of exchange reaction. A manufacturing apparatus having a static mixing device in which the mixing discharge pipe and the supply pipe are connected so that the axis of the mixing discharge pipe and the axes of the plurality of supply pipes intersect at one place and the axes coincide at the intersection. The method for producing organic acid metal salt particles according to claim 1, wherein the simultaneous metering and mixing are performed. The organic acid and the mixed acid discharge pipe and the supply pipe are connected to each other so that the axis of the mixed discharge pipe and the plurality of supply pipes intersect at one point, and the axes coincide at the intersection. In the method for producing organic acid metal salt particles, an aqueous solution or suspension of an organic acid alkali metal salt and a metal salt aqueous solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt are simultaneously metered and mixed. Conditions for cooling an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt from a high temperature (70 ° C. to 100 ° C.) to a low temperature (0 ° C. to 60 ° C.) at a cooling rate of 1 ° C./min to 1000 ° C./min. The manufacturing method of the organic acid metal salt particle characterized by the above-mentioned. The method for producing organic acid metal salt particles according to claim 3, wherein the cooling rate is 10 ° C / min to 1000 ° C / min. The method for producing organic acid metal salt particles according to claim 3 or 4, wherein the cooling is performed using an online heat exchanger. The said organic acid is a fatty acid, The manufacturing method of the organic acid metal salt particle of any one of Claims 1-5 characterized by the above-mentioned. An apparatus for producing organic acid metal salt particles, comprising at least the following devices (1) to (4):
(1) a first supply device for supplying an aqueous solution or suspension of an organic acid and an organic acid alkali metal salt to a static mixing device; (2) an organic acid and an organic acid alkali metal salt supplied to the static mixing device; A cooling device that cools the aqueous solution or suspension; (3) a second supply device that supplies an aqueous metal salt solution containing a metal ion capable of exchange reaction with an alkali metal of the organic acid alkali metal salt to a static mixing device; 4) A static mixing device that mixes the supplies from the first supply device and the second supply device and discharges the organic acid metal salt-containing liquid. The said organic acid is a fatty acid, The manufacturing apparatus of the organic acid metal salt particle of Claim 7 characterized by the above-mentioned. It was manufactured by at least one kind of photosensitive silver halide particles, silver ion reducing agent, binder, and organic acid metal salt particle manufacturing method according to any one of claims 1 to 6 on a support. A silver salt photothermographic dry imaging material comprising a photosensitive layer containing organic acid silver salt particles.

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