JP2009069755A - Silver salt photothermographic dry imaging material, method for producing same, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material which excels in raw stock preservability (preservability before heat development), exhibits a high maximum density even in the case of rapid heat development while having low fog, and excels also in stability of a silver image after heat development, a method for producing the same, and an image forming method using the same. <P>SOLUTION: The silver salt photothermographic dry imaging material has a photosensitive layer containing photosensitive silver halide grains, a non-photosensitive aliphatic carboxylic acid silver salt and a silver ion reducing agent, wherein the non-photosensitive aliphatic carboxylic acid silver salt is produced using a plurality of different aliphatic carboxylic acid mixtures different in behenic acid content ratio as starting materials. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a silver salt photothermographic dry imaging material (also referred to as “photothermographic material” or “photothermographic material”), a production method thereof, and an image forming method using the same.

  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.

  By the way, in these silver salt photothermographic dry imaging materials, photosensitive silver halide particles placed in a photosensitive layer (image forming layer) are used as a photosensor, and aliphatic carboxylic acid silver salt is used as a source of silver ions. An image is formed by heat development usually at 80 ° C. or higher with a built-in reducing agent, and fixing is not performed (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1).

  However, since the silver salt photothermographic dry imaging material contains an aliphatic carboxylic 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 the exposure, only heat development is performed and fixing is not performed. Therefore, all or part of the aliphatic carboxylic acid silver salt and the reducing agent coexist, and metal silver is sensed by heat or light during long-term storage. There is a problem that it is generated in the material and the image quality of the silver image is likely to change. Here, the reducible aliphatic carboxylic acid silver salt, which is one of the materials important for image formation, is often a mixture of aliphatic carboxylic acid silver salts having different chain lengths. The higher the content of behenic acid, the higher the image storage stability (see Non-Patent Document 2). It was difficult to prepare an aliphatic carboxylic acid silver salt excellent in dispersibility and excellent in storage stability using these mixtures.

Patent Documents 3 and 4 mention the crystal structure of an aliphatic carboxylic acid silver salt that accompanies a change in silver behenate content. Furthermore, Patent Documents 5 and 6 also mention control means for performing addition time, method, and the like at the time of preparing the aliphatic carboxylic acid silver salt solution, but are complicated.
US Pat. No. 3,152,904 US Pat. No. 3,487,075 JP 2007-25542 A JP 2005-37566 A JP 2005-37578 A Japanese Patent Laid-Open No. 2005-37579 Dry Silver Photographic Materials, Handbook of Imaging Materials, Marcel Dekker, New York, p. 48 (1991) M.M. Ikeda, Photogr. Sci. Eng. , 24, 277 (1980)

  The present invention has been made in view of the above problems and circumstances, and the solution to the problem is excellent in raw storability (storability before heat development), low fog, and maximum density even in short time heat development. It is intended to provide a silver salt photothermographic dry imaging material that is high in image quality and also excellent in stability of a silver image after heat development, a production method thereof, and an image forming method using the same.

  The above-mentioned problem according to the present invention is solved by the following means.

  1. In a silver salt photothermographic dry imaging material having a photosensitive layer containing a photosensitive silver halide grain, a non-photosensitive aliphatic carboxylic acid silver salt, and a silver ion reducing agent, the non-photosensitive aliphatic carboxylic acid silver salt is A silver salt photothermographic dry imaging material manufactured using a plurality of different aliphatic carboxylic acid mixtures having different behenic acid content ratios as raw materials.

  2. The non-photosensitive aliphatic carboxylic acid silver salt has a dry aliphatic carboxylic acid silver salt (powder crystal state) interlayer distance of 57 to 60 mm and an X-ray diffraction peak half width of 0.15 to 0.40. 2. The silver salt photothermographic dry imaging material as described in 1 above, wherein

  3. The silver salt photothermographic dry according to 1 or 2 above, wherein 95% by mass or more of the constituents of the aliphatic carboxylic acid mixture is composed of behenic acid, arachidic acid, and stearic acid. Imaging material.

  4). At least one of the plurality of different aliphatic carboxylic acid mixtures contains 40 to 60% by mass of behenic acid, and the other contains 85 to 95% by mass of behenic acid. The silver salt photothermographic dry imaging material according to claim 1.

  5). The non-photosensitive aliphatic carboxylic acid silver salt is a mixture ratio (mass ratio) of an aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid and an aliphatic carboxylic acid mixture containing 85 to 95% by mass of behenic acid. The silver salt photothermographic dry imaging material according to any one of 1 to 4 above, wherein the silver salt photothermographic dry imaging material is manufactured using 5: 1 to 1: 8.

  6). 6. The silver salt photothermographic dry imaging material as described in 5 above, wherein the mixing ratio is 1: 1 to 1: 4.

  7. 7. The silver salt as described in 6 above, wherein the aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid contains 10 to 30% by mass of stearic acid in the mixing ratio described in 6 above. Photothermographic dry imaging material.

  8). 8. The mixing ratio described in 6 above, wherein the aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid contains 10 to 25% by mass of stearic acid. Silver salt photothermographic dry imaging material.

  9. The manufacturing method of the silver salt photothermographic dry imaging material characterized by manufacturing the silver salt photothermographic dry imaging material as described in any one of said 1-8.

  10. An image forming method based on digital image information, wherein a silver image is formed using the silver salt photothermographic dry imaging material according to any one of 1 to 8 above.

  11. In the image forming method based on digital image information, the silver salt photothermographic dry imaging material according to any one of 1 to 8 above is exposed with a laser beam having a wavelength in a wavelength region of 780 to 820 nm, and subsequently An image forming method, wherein a silver image is formed by heat development at a temperature of 110 to 150 ° C. for 10 seconds or less.

  By the above means of the present invention, it has excellent raw storability (storability before heat development), low fog, high density even in short time heat development, and further stability of silver image after heat development. It is also possible to provide an excellent silver salt photothermographic dry imaging material, a method for producing the same, and an image forming method using the same.

  The silver salt photothermographic dry imaging material of the present invention is a silver salt photothermographic dry imaging material having a photosensitive layer containing photosensitive silver halide grains, a non-photosensitive aliphatic carboxylic acid silver salt, and a silver ion reducing agent. The non-photosensitive aliphatic carboxylic acid silver salt is produced using a plurality of different aliphatic carboxylic acid mixtures having different behenic acid content ratios as raw materials. This feature is a technical feature common to the inventions according to claims 1 to 11.

  Hereinafter, the present invention and its components will be described in detail.

[Non-photosensitive aliphatic carboxylic acid silver salt]
The non-photosensitive aliphatic carboxylic acid silver salt used in the present invention is relatively stable to light, but is heated to 80 ° C. or higher in the presence of exposed photosensitive silver halide grains and a reducing agent. In this case, the silver salt functions as a silver ion supplier and forms a silver image. The non-photosensitive aliphatic carboxylic acid silver salt may be any aliphatic carboxylic acid silver salt capable of supplying silver ions that can be reduced by a reducing agent. The aliphatic carboxylic acid silver salt is particularly preferably a silver salt of a long-chain aliphatic carboxylic acid (having 10 to 30, preferably 15 to 28 carbon atoms). Preferred examples of the aliphatic carboxylic acid silver salt include silver lignocerate, silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, erucic acid. Including silver and mixtures thereof.

  In the present invention, the non-photosensitive aliphatic carboxylic acid silver salt is produced by performing a silveration reaction using fatty acid carboxylic acids having different fatty acid compositions. That is, the non-photosensitive aliphatic carboxylic acid silver salt is produced using a plurality of different aliphatic carboxylic acid mixtures having different behenic acid content ratios as raw materials.

  In addition, as for the said aliphatic carboxylic acid mixture, the aspect in which all 95 mass% or more of a structural component is comprised with behenic acid, arachidic acid, and a stearic acid is preferable. Furthermore, it is preferable that at least one of the plurality of different aliphatic carboxylic acid mixtures contains 40 to 60% by mass of behenic acid, and the other contains 85 to 95% by mass of behenic acid.

  Further, in particular, the non-photosensitive aliphatic carboxylic acid silver salt comprises an aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid and an aliphatic carboxylic acid mixture containing 85 to 95% by mass of behenic acid. : 1 to 1: 8. Furthermore, the mixing ratio is preferably 1: 1 to 1: 4.

  Moreover, in the said mixing ratio, it is preferable that 10-30 mass% of stearic acid is contained in the aliphatic carboxylic acid mixture containing 40-60 mass% of behenic acid. Furthermore, in the mixing ratio, the aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid preferably contains 10 to 25% by mass of stearic acid.

  In the present invention, the non-photosensitive aliphatic carboxylic acid silver salt preferably contains 85 mol% or more and less than 95 mol% of silver behenate. In addition, it is preferable to use an aliphatic carboxylic acid silver salt having a silver erucate content of 2 mol% or less, more preferably 1 mol% or less, and still more preferably 0.1 mol% or less.

(Layer distance and half width of aliphatic carboxylic acid silver salt crystals)
Hereinafter, the interlayer distance and the half-value width of the non-photosensitive aliphatic carboxylic acid silver salt crystal will be described.

  The aliphatic carboxylic acid silver salt according to the present invention preferably has a dry powder crystal interlayer distance of 57 to 60 mm (5.7 to 6.0 nm). Moreover, it is preferable that the X-ray diffraction peak half width is 0.15 to 0.40.

The interlayer distance and half width of the crystal of the aliphatic carboxylic acid silver salt can be calculated from the X-ray diffraction peak value using Formula 1 which is a Bragg condition.
(Formula 1): d = λn / 2 sin θ
In the formula, d is an interlayer distance (interval between crystal lattice planes), λ is an X-ray wavelength, θ is an X-ray incident angle, and n is a positive integer.

In the case of an aliphatic carboxylic acid silver salt, “AgOOC—C _n H _2n —CH ₃ .CH ₃ —C _n H _2n —COOAg” becomes one unit and appears in the peak of X-ray diffraction. For this reason, the interlayer distance is close to the chain length of two molecules, but varies depending on the disorder of the crystal structure and the composition of the aliphatic carboxylic acid silver salt.

  The interlayer distance of the aliphatic carboxylic acid silver salt according to the present invention was measured using X'Pert Data Viewer manufactured by PANalytical. The X-ray used for the measurement was CuKα1 ray (wavelength 1.5408 angstrom), and the measurement surface was set on the stage in the direction of the irradiation surface. The measurement was performed at 2θ = 5 ° to 50 °, and the average of 6 peaks of n = 3 to 8 was defined as the interlayer distance and the half-value width of the present invention.

  The sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt particles is preferably 0.05 to 0.5 μm. More preferably, it is 0.10 to 0.5 μm. The particle size distribution is preferably monodisperse. The monodispersity can be expressed by the standard deviation of the average diameter, and the standard deviation of the aliphatic carboxylic acid silver salt particles of the present invention is preferably 0.3 or less. Furthermore, it is preferable that it is 0.2 or less.

  Measurement of the particle size and particle size distribution in this case is a laser diffraction method, centrifugal sedimentation light transmission method, X-ray transmission method, electrical detection band method, shading method, ultrasonic attenuation spectroscopy, a method of calculating from an image, etc. Although it can each obtain | require with the measuring method of the particle size distribution generally known, the method of calculating from a laser diffraction method and an image is preferable among these. Furthermore, the laser diffraction method is preferable, and the aliphatic carboxylic acid silver salt particles dispersed in the liquid can be measured with a commercially available laser diffraction particle size distribution analyzer. Specific examples of the particle size and particle size distribution measuring method are shown below.

  In a 100 ml beaker, a sample of 0.01 g of aliphatic carboxylic acid silver salt particles is taken, 0.1 g of nonionic activator NS-210 (manufactured by NOF Corporation) and 40 ml of water are added, followed by ultrasonication at room temperature. The average particle size and standard deviation can be measured with a laser diffraction particle size analyzer SALD-2000 (manufactured by Shimadzu Corporation) with the obtained dispersion.

  To prepare an aliphatic carboxylic acid silver salt so that the average equivalent sphere diameter is 0.05 to 0.5 μm and the standard deviation of the equivalent sphere diameter is 0.3 or less, the reaction is carried out by the following mixing method. It is preferable to prepare them.

  The aliphatic carboxylic acid silver salt particles are prepared by reacting a solution containing silver ions with an aliphatic metal carboxylate salt solution or suspension. The solution containing silver ions is preferably an aqueous silver nitrate solution, the aliphatic carboxylic acid metal salt solution or suspension is an aqueous solution or an aqueous dispersion, and the addition and mixing are preferably performed simultaneously. Any method such as a method of adding to the liquid surface of the bath or a method of adding to the liquid may be used, but a method of adding and mixing in the transfer means is preferred. Mixing in the transfer means means line mixing, and before the mixture of the solution containing silver ions and the aliphatic metal carboxylic acid alkali metal salt solution or suspension enters the batch storing the mixture containing the reactants. It is performed. As the stirring means in the mixing section, any means such as mechanical stirring such as a homomixer, static mixer, turbulent flow effect or the like may be used, but it is preferable not to use mechanical stirring. In addition, the mixing in the transfer means includes a solution containing silver ions, an alkali metal salt of an aliphatic carboxylic acid salt or a suspension, water, a circulated liquid of a mixed liquid stored in a batch after mixing, and the like. Liquids or suspensions may be mixed.

  In the present invention, the concentration of the aqueous silver nitrate solution is preferably 1 to 15% by mass, and the concentration of the aliphatic carboxylic acid metal salt aqueous solution or the aqueous dispersion is preferably in the range of 1 to 5% by mass. In a low concentration range outside the above-mentioned concentration range, productivity is remarkably deteriorated and is not realistic, and in a high concentration range, it is difficult to adjust the particle size and particle size distribution to the range of the present invention. The mixing molar ratio of silver nitrate to the aliphatic carboxylic acid alkali metal salt is preferably in the range of 0.9 to 1.1, and outside the range, the grain size and grain distribution can be adjusted within the range of the present invention. In addition to difficulty, the yield of aliphatic carboxylic acid silver salt is reduced, and the formation of silver oxide that causes fogging is likely to occur.

  The prepared aliphatic carboxylic acid silver salt is preferably washed with water and then dried from the viewpoint of storage stability. Washing with water is performed mainly for the purpose of removing unreacted ions, but it may be performed with an organic solvent in consideration of the subsequent drying step. The washing with water is preferably performed at 50 ° C. or lower. Furthermore, it is preferable to carry out at 30 degrees C or less. When it is carried out at 50 ° C. or higher, it becomes difficult to adjust the particle size and particle distribution within the scope of the present invention. The drying is preferably performed at a temperature lower than the phase transition temperature of the aliphatic carboxylic acid silver salt. Furthermore, it is preferable to carry out at 50 degrees C or less, and it is preferable to carry out at the lowest possible temperature. Drying above the phase transition temperature makes it difficult to adjust the particle size and particle distribution within the scope of the present invention.

  In the present invention, the preparation of the aliphatic carboxylic acid silver salt is preferably performed in the absence of photosensitive silver halide grains. In the preparation in the presence of photosensitive silver halide grains, it is difficult to adjust the grains and grain distribution of the aliphatic carboxylic acid silver salt grains within the scope of the present invention because of compatibility with fogging performance.

The aliphatic carboxylic acid silver salt can be used in a desired amount, but the total silver amount including the silver halide grains is preferably 0.8 to 1.5 g / m ² as the coated silver amount, more preferably 1.0 to A range of 1.3 g / m ² is preferred.

(Types of alkali metal salts)
Examples of the types of alkali metal salts that can be used include sodium hydroxide, potassium hydroxide, and lithium hydroxide. Among these, it is preferable to use one kind of alkali metal salt such as potassium hydroxide, but it is also preferable to use sodium hydroxide and potassium hydroxide in combination. As a combined ratio, it is preferable that the molar ratio of both of the above hydroxide salts is in the range of 10:90 to 75:25. When it reacts with an aliphatic carboxylic acid to become an alkali metal salt of an aliphatic carboxylic acid, the viscosity of the reaction solution can be controlled to a good state by using it within the above range.

(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 not forming a silver salt, and the ratio of the former is lower than that of the latter. Is preferable from the viewpoint of image storage stability and the like. That is, the emulsion according to the present invention is characterized in that the aliphatic carboxylic acid silver salt grains are 90% or more based on the total of the free aliphatic carboxylic acid and the aliphatic carboxylic acid silver salt grains. In particular, it is preferable to contain 90-96 mol%. The ratio can be adjusted by the addition amount of aliphatic carboxylic acid and a water-soluble silver salt (for example, silver nitrate), pH, reaction temperature, and the like when preparing aliphatic carboxylic acid silver salt particles.

  Specifically, by determining the total aliphatic carboxylic acid amount and the free aliphatic carboxylic acid amount by the following methods, respectively, the aliphatic carboxylic acid silver salt amount and the free aliphatic carboxylic acid amount and the respective amounts The ratio or the ratio of the free fatty acid to the 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 fatty acids))
1) Weigh accurately about 10 mg of sample (the mass removed when peeling from the photosensitive material) and place 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) Add 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 what has adhered to the cooling tube into the eggplant-shaped flask (twice). 5) The obtained reaction solution is extracted into an ethyl acetate phase (100 ml of ethyl acetate and 70 ml of water are added and liquid separation extraction is performed twice). 6) The ethyl acetate phase is vacuum dried at room temperature for 30 minutes. 7) Into a 10 ml volumetric flask is placed 1 ml of a benzanthrone solution (about 100 mg of benzanthrone is dissolved in toluene and made up to a volume of 100 ml with toluene) as an internal standard. 8) Dissolve the sample in 6) above in toluene, put it in the volumetric flask in 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-130 m × 0.32 mm × 0.25 μm (manufactured by HP), inlet: 250 ° C., detector: 280 ° C., oven: 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 aliphatic carboxylic acid is extracted). 2) It is filtered and the filtrate is placed in a 200 ml eggplant type flask and dried to solid (free aliphatic 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) Add Teflon (registered trademark) zeolite and reflux for 60 minutes. 5) 60 ml of water and 60 ml of ethyl acetate are added to the obtained reaction solution, and the methyl esterified product of the aliphatic carboxylic acid is extracted into the ethyl acetate phase (separate extraction is performed twice). 6) The ethyl acetate phase is dried and dried for 30 minutes. 7) Place 1 ml of benzanthrone solution (the same as that used for the determination of the total aliphatic carboxylic acid amount) in a 10 ml volumetric flask. 8) Dissolve 6) with toluene and put into the volumetric flask of 7). 9) The GC measurement is performed under the same measurement conditions as the determination of the total aliphatic carboxylic acid amount.

(Structure and shape of aliphatic carboxylic acid silver salt)
The shape of the aliphatic carboxylic acid silver salt 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 scale shape. In the present invention, scale-like aliphatic carboxylic acid silver salts and short needle-shaped or cuboid-shaped aliphatic carboxylic acid silver salts having a major axis / minor axis length ratio of 5 or less are preferably used.

  In addition, the scale-like aliphatic carboxylic acid silver salt in this invention is defined as follows. When the aliphatic carboxylate silver salt is observed with an electron microscope, the shape of the aliphatic carboxylate silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are a, b, and c from the shortest side (c is b X) is calculated by using the shorter numerical values a and b as follows.

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

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

  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 No. 1168069A1 and Japanese Patent Application Laid-Open No. 2002-23303. In the case of a core / shell structure, all or part of either the core part or the shell part is an aliphatic carboxylic acid silver salt other than the long-chain aliphatic carboxylic acid silver salt, such as phthalic acid, benzimidazole, etc. A silver salt of the organic compound may be used as a constituent of the crystal particles.

[Photosensitive silver halide grains]
Photosensitive silver halide grains can inherently absorb light as an intrinsic property of silver halide crystals, or can absorb visible to infrared light by an artificial physicochemical method, and Processed and manufactured so that physicochemical changes can occur in the silver halide crystal and / or on the crystal surface when light in any region within the light wavelength range of the ultraviolet light region to the infrared light region is absorbed. Refers to silver halide crystal grains.

  The silver halide grains according to the present invention can be prepared as a silver halide grain emulsion (also referred to as a silver halide emulsion) using a known method. That is, any of acid method, neutral method, ammonia method, etc. may be used, and as a method of reacting soluble silver salt and soluble halogen salt, any one of one-side mixing method, simultaneous mixing method, combination thereof, etc. may be used. Of these methods, the so-called controlled double jet method in which silver halide grains are prepared while controlling the formation conditions is preferred.

  Usually, silver halide seed grains are divided into two stages, grain nucleation and grain growth, and these may be carried out continuously at once, or nucleation (seed grain) formation and grain growth may be separated. The method of performing may be used. The controlled double jet method in which the particle formation is controlled by controlling the pAg, pH, etc., which are the particle formation conditions, is preferable because the particle shape and particle can be controlled. For example, when carrying out a method in which nucleation and grain growth are performed separately, first, a silver salt aqueous solution and a halide aqueous solution are uniformly and rapidly mixed in an aqueous gelatin solution, followed by nucleation (nucleation step), and then control. Silver halide grains are prepared by a grain growth step in which grains are grown while supplying a silver salt aqueous solution and a halide aqueous solution under the pAg, pH and the like. After the grain formation, a desired silver halide grain emulsion is obtained by removing unnecessary salts by a known desalting method such as noodle method, flocculation method, ultrafiltration method, electrodialysis method, etc. be able to.

  The particle size distribution of the silver halide grains according to the present invention is preferably monodispersed. The monodispersion mentioned here means that the coefficient of variation of the particle diameter obtained by the following formula is 30% 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
Examples of the shape of the silver halide grains include cubes, octahedrons, tetrahedron grains, tabular shapes, spherical shapes, rod shapes, potato shapes and the like. Among these, cubic shapes, octahedrons, tetrahedrons, or flat plates are particularly preferable. Silver halide grains are preferred.

  The average aspect ratio when using tabular silver halide grains is preferably 1.5 to 100, more preferably 2 to 50. These are described in US Pat. Nos. 5,264,337, 5,314,798, and 5,320,958, and the desired tabular grains can be easily obtained. Further, grains having rounded corners of silver halide grains can be preferably used.

  The crystal habit on the outer surface of the silver halide grain is not particularly limited, but when a sensitizing dye having crystal habit (plane) selectivity is used in the adsorption reaction of the sensitizing dye on the surface of the silver halide grain. It is preferable to use silver halide grains having a relatively high proportion of crystal habits adapted to the selectivity. For example, when using a sensitizing dye that is selectively adsorbed on the crystal face of the Miller index [100], the proportion of the [100] face on the outer surface of the silver halide grain is preferably high, and this ratio is 50 % Or more, more preferably 70% or more, and particularly preferably 80% or more. The ratio of the Miller index [100] plane is a T.K. based on the adsorption dependency of the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. Technol. 29, 165 (1985).

  The silver halide grains used in the present invention are preferably prepared using low molecular weight gelatin having an average molecular weight of 50,000 or less at the time of forming the grains, and particularly preferably used at the time of nucleation of silver halide grains. The low molecular weight gelatin preferably has an average molecular weight of 50,000 or less, more preferably 2,000 to 40,000, and particularly preferably 5,000 to 25,000. The average molecular weight of gelatin can be measured by gel filtration chromatography. Low molecular weight gelatin can be decomposed by adding gelatin-degrading enzyme to a commonly used gelatin aqueous solution with an average molecular weight of about 100,000, hydrolyzing by adding acid or alkali, and heating under atmospheric pressure or pressure. Can be obtained by thermal decomposition, decomposition by ultrasonic irradiation, or a combination of these methods. The concentration of the dispersion medium during the nucleation of the silver halide grains is preferably 5% by mass or less, and more preferably at a low concentration of 0.05 to 3.0% by mass.

  The silver halide grains used in the present invention preferably use a compound represented by the following general formula at the time of grain formation.

YO (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH ₂ O) _p (CH ₂ CH ₂ O) _n Y
In the formula, Y represents a hydrogen atom, —SO ₃ M, or —CO—B—COOM, and M represents an ammonium group substituted with a hydrogen atom, an alkali metal atom, an ammonium group, or an alkyl group having 5 or less carbon atoms. And B represents a chain or cyclic group forming an organic dibasic acid. m and n each represents 0 to 50, and p represents 1 to 100.

  The polyethylene oxide compound represented by the above general formula is a step of producing a gelatin aqueous solution when producing a normal silver halide photographic light-sensitive material, a step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, It has been preferably used as an antifoaming agent for significant foaming when the emulsion raw material is stirred or moved, such as a step of coating an emulsion on a support. This is described in JP-A-44-9497. The polyethylene oxide compound also functions as an antifoaming agent during nucleation. The compound represented by the above general formula is preferably used at 1% by mass or less, more preferably 0.01 to 0.1% by mass with respect to silver.

  The polyethylene oxide compound only needs to be present at the time of nucleation, and is preferably added in advance to the dispersion medium before nucleation, but it may be added during nucleation or a silver salt used at the time of nucleation. You may add and use for aqueous solution or halide aqueous solution. Preferably, it is used by adding 0.01 to 2.0% by mass to the aqueous halide solution or both aqueous solutions. Also, the compound is preferably present for at least 50% of the nucleation step, more preferably 70% or more. The polyethylene oxide compound may be added as a powder or dissolved in a solvent such as methanol.

  The temperature at the time of nucleation is usually 5 to 60 ° C., preferably 15 to 50 ° C. Even if the temperature is constant, the temperature rise pattern (the temperature at the start of nucleation is 25 ° C. It is preferable to control the temperature within the above temperature range even when the temperature is gradually increased and the temperature at the end of nucleation is 40 ° C.) and vice versa.

The concentration of the aqueous silver salt solution and aqueous halide solution used for nucleation is preferably 3.5 mol / L or less, and more preferably used in a low concentration range of 0.01 to 2.5 mol / L. The addition rate of silver ions during nucleation is preferably 1.5 × 10 ^{−3 to} 3.0 × 10 ⁻¹ mol / min, more preferably 3.0 × 10 ^{−3 to} 8.0, per liter of the reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can usually be set in a range of 1.7 to 10, but it is preferably pH 2 to 6 because the particle size distribution of nuclei to be formed is broadened at the pH on the alkali side. Moreover, pBr at the time of nucleation is 0.05-3.0 normally, Preferably it is 1.0-2.5, More preferably, it is 1.5-2.0.

  The average grain size of the silver halide grains is usually 10 to 50 nm, preferably 10 to 40 nm, and more preferably 10 to 35 nm. If the average grain size of the silver halide grains is smaller than 10 nm, the image density decreases, or the light irradiation image storage stability (the image obtained by heat development is used for diagnosis in a bright room or stored in a bright room) Storage stability) may be deteriorated. On the other hand, if it exceeds 50 nm, the image density may decrease.

  The average grain diameter referred to here is the length of the edge of the silver halide grains when the silver halide grains contained in the silver halide grain emulsion are cubic or octahedral so-called normal crystals. To tell. Further, when the silver halide grain is a tabular grain, it means the diameter when converted into a circular image having the same area as the projected area of the main surface. In addition, in the case of non-normal crystals, for example, in the case of spherical particles, rod-shaped particles, etc., the diameter when considering a sphere equivalent to the volume of the silver halide grains is calculated as the particle size. The measurement is performed using an electron micrograph, and the average particle diameter is obtained by averaging the measured values of the particle diameters of 300 particles.

  In the present invention, the gradation of the image density can be adjusted by using silver halide grains having an average particle diameter of 55 to 100 nm and silver halide grains having an average particle diameter of 10 to 50 nm in combination. In addition, it is possible to improve the image density and to improve (reduce) the decrease in image density over time. The ratio (mass ratio) of silver halide grains having an average particle diameter of 10 to 50 nm and silver halide grains having an average particle diameter of 55 to 100 nm is preferably 95: 5 to 50:50, more preferably 90. : 10-60: 40.

  As described above, when two types of silver halide grain emulsions having an average particle diameter are used, the two types of silver halide emulsions may be mixed and contained in the photosensitive layer. In order to adjust the gradation, it is also preferred that the photosensitive layer is composed of two or more layers, and each layer contains the silver halide grain emulsions having the two average grain sizes separately.

(Silver halide grains having a silver iodide content of 5 to 100 mol%)
As the silver halide grains, silver halide grains containing silver iodide can be preferably used. As the halogen composition, the silver iodide content is preferably 5 to 100 mol%. More preferably, it is 40-100 mol%, More preferably, it is 70-100 mol%, Most preferably, it is 90-100 mol%. If the silver iodide content is in this range, the intra-grain halogen composition distribution may be uniform, may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure having a high silver iodide content inside and / or on the surface can also be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles.

  As a method for introducing silver iodide into the silver halide grains, a method of adding an alkali iodide aqueous solution during grain formation, fine grain silver iodide, fine grain silver iodobromide, fine grain silver iodochloride, fine grain silver iodochlorobromide Among them, a method of adding at least one fine particle, a method using an iodide ion releasing agent described in JP-A-5-323487 and 6-11780, and the like are preferable.

  The silver halide grain according to the present invention preferably exhibits direct transition absorption derived from the silver iodide crystal structure at a wavelength of 350 to 440 nm. Whether or not these silver halide grains have light absorption of direct transition can be easily distinguished by the fact that exciton absorption caused by direct transition is observed in the vicinity of 400 to 430 nm.

(Heat conversion internal latent image type silver halide grains)
The photosensitive silver halide grains according to the present invention are heat-converted internal latent image type (internal latent image type after heat development) silver halide grains disclosed in JP-A Nos. 2003-270755 and 2005-106927. Silver halide grains whose surface sensitivity is lowered by converting from the surface latent image type to the 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 that suppresses the formation of latent images on the surface. preferable.

  The heat-converted internal latent image type silver halide grains are 0.001 to 0.001 mol per mol of an aliphatic carboxylic acid silver salt that can function as a silver ion source, as in the case of ordinary surface latent image type silver halide grains. It is preferably used in the range of 7 mol, preferably 0.03 to 0.5 mol.

[Amphiphilic dispersion of silver halide grains]
In the production process of silver salt photothermographic dry imaging materials, from the viewpoint of improving photographic performance and color tone, silver halide grains are prevented from agglomerating, and silver halide grains are dispersed relatively uniformly and finally developed. It is preferable that silver can be controlled to a desired shape.

  In order to prevent aggregation, to uniformly disperse, etc., the gelatin used is preferably one in which hydrophilic properties such as amino groups and carboxyl groups of gelatin are chemically modified to modify the properties of gelatin according to the conditions of use. For example, examples of the hydrophobic modification of the amino group in the gelatin molecule include phenylcarbamoylation, phthalation, hatching, acetylation, benzoylation, and nitrophenylation, but are not particularly limited thereto. Further, the substitution rate is preferably 95% or more, more preferably 99% or more. In addition, hydrophobic modification of the carboxyl group may be combined, and examples thereof include methyl esterification and amidation, but are not particularly limited thereto. The substitution rate of the carboxyl group is preferably 50 to 90%, more preferably 70 to 90%. Here, the hydrophobic group in the above-mentioned hydrophobization modification refers to a group whose hydrophobicity is increased by substituting the amino group and / or carboxyl group of gelatin.

  It is also preferable depending on the purpose that the silver halide grain emulsion is prepared by using a polymer that dissolves in both water and an organic solvent as described below, instead of gelatin or in combination with gelatin. For example, it is particularly preferred when the silver halide grain emulsion is coated with 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 that is soluble in both the water and the organic solvent may be a natural polymer, a synthetic polymer, or a copolymer. For example, gelatins, rubbers and the like that have been modified 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.

  Examples of the polymer include polyvinyl alcohols, hydroxyethyl celluloses, cellulose acetates, cellulose acetate butyrates, polyvinyl pyrrolidones, casein, starch, polyacrylic acid and acrylic acid esters, polymethylmethacrylic acid and methacrylic acid esters, Polyvinyl chlorides, polymethacrylic acids, styrene-maleic anhydride copolymers, styrene-acrylonitrile copolymers, styrene-butadiene copolymers, polyvinyl acetals (polyvinyl formal and polyvinyl butyral), polyesters, polyurethane Phenoxy resins, polyvinylidene chlorides, polyepoxides, polycarbonates, polyvinyl acetates, polyolefins, cellulose esters, polyamides, etc. It is. Several types of these polymers may be copolymers, and polymers obtained by copolymerizing monomers of acrylic acid, methacrylic acid and esters thereof are particularly preferable.

  The polymer may be a polymer that dissolves in both water and an organic solvent in the same state, but includes a polymer that can be dissolved or insolubilized in water or an organic solvent by controlling pH or temperature. For example, although a polymer having an acidic group such as a carboxyl group becomes hydrophilic in a dissociated state depending on the type, it becomes oleophilic and soluble in a solvent when the pH is lowered to a non-dissociated state. Conversely, a polymer having an amino group becomes lipophilic when the pH is raised, and becomes ionized and water-soluble when the pH is lowered. Nonionic activators are well known for the cloud point phenomenon, but they become lipophilic and soluble in organic solvents when the temperature rises, and they are hydrophilic, that is, soluble in water when the temperature is lowered. Polymers such as poly-N-isopropylacrylamide and copolymers thereof as well-known thermosensitive polymers are also included in the present invention. 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, although it may be adjusted by adjusting the conditions such as pH as described above or not adjusted. The organic solvent preferably has a solubility of 5% by mass or more (25 ° C.) in methyl ethyl ketone. From the viewpoint of solubility, so-called block polymers, graft polymers, comb polymers, and the like are more suitable as polymers that are soluble in both water and organic solvents used in the present invention. Comb polymers are particularly preferred. The isoelectric point of the polymer is preferably pH 6 or less.

  When manufacturing a comb polymer, various methods can be used, but it is desirable to use a monomer capable of introducing a side chain having a molecular weight of 200 or more into the comb part (side chain). In particular, it is preferable to use a polyoxyalkylene group-containing ethylenically unsaturated monomer such as ethylene oxide or propylene oxide. As the polyoxyalkylene group-containing ethylenically unsaturated monomer, those having a polyoxyalkylene group represented by the following general formula are particularly preferable.

-(EO) _k- (PO) _m- (TO) _n- R
In the formula, E represents an ethylene group, P represents a propylene group, T represents a butylene group, and R represents a substituent. Examples of the butylene group include a tetramethylene group and an isobutylene group. k represents an integer of 1 to 300, m represents 0 to 60, and n represents an integer of 0 to 40. Preferably, k is 1 to 200, m is 0 to 30, and n is 0 to 20. However, k + m + n ≧ 2 is preferable in order to be a comb polymer. The polyoxyalkylene group-containing ethylenically unsaturated monomer may be used alone or in combination of two or more.

  The substituent represented by R represents an alkyl group, an aryl group, a heterocyclic group, and the like. As the alkyl group, a group such as methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, or the like, or an aryl group As phenyl, naphthyl and the like, and heterocyclic groups as thienyl, pyridyl and the like. These groups are further halogen atoms, alkoxy groups (methoxy, ethoxy, butoxy, etc.), alkylthio groups (methylthio, butylthio, etc.), acyl groups (acetyl, benzoyl, etc.), alkanamide groups (acetamide, propionamide, etc.) , An arylamide group (such as benzoylamide) and the like may be substituted. These substituents may be further substituted with these groups.

  The polyoxyalkylene group represented by the general formula can be introduced into the polymer by using an ethylenically unsaturated monomer having these polyoxyalkylene groups. Examples of ethylenically unsaturated monomers having these groups include polyoxyalkylene acrylates (and methacrylates), which are commercially available hydroxypoly (oxyalkylene) materials such as the trade name Pluronic (Pluronic (Pluronic (Pluronic)). Asahi Denka Kogyo)], Adeka Polyether (Asahi Denka Kogyo), Carbowax [Carbowax (Glico Products)], Triton [Toriton (Rohm and Hass)] And P.A. E. G (made by Daiichi Kogyo Seiyaku Co., Ltd.) etc. can be manufactured by making it react with acrylic acid, methacrylic acid, acryl chloride, methacryl chloride, acrylic acid anhydride, etc. by a well-known method. Separately, poly (oxyalkylene) diacrylate produced by a known method can also be used.

  Moreover, as a commercially available monomer, as a hydroxyl group-terminated polyalkylene glycol mono (meth) acrylate manufactured by NOF Corporation, Blemmer PE-90, Blemmer PE-200, Blemmer PE-350, Blemmer AE-90, Blemmer AE- 200, Blemmer AE-400, Blemmer PP-1000, Blemmer PP-500, Blemmer PP-800, Blemmer AP-150, Blemmer AP-400, Blemmer AP-550, Blemmer AP-800, Blemmer 50 PEP-300, Blemmer 70 PEP- 350B, Blemmer AEP series, Blemmer 55PET-400, Blemmer 30PET-800, Blemmer 55PET-800, Blemmer AET series, Blemmer 30PPT-800, Buremer Ma 50PPT-800, Blemmer 70PPT-800, Blemmer APT series, Brenmer 10PPB-500B, and the like Brenmer 10APB-500B. Similarly, as an alkyl terminal polyalkylene glycol mono (meth) acrylate manufactured by NOF Corporation, Blemmer PME-100, Blemmer PME-200, Blemmer PME-400, Blemmer PME-1000, Blemmer PME-4000, Blemmer AME-400, Blemmer 50POEP-800B, Blemmer 50AOEP-800B, Blemmer PLE-200, Blemmer ALE-200, Blemmer ALE-800, Blemmer PSE-400, Blemmer PSE-1300, Blemmer ASE series, Blemmer PKEP series, Blemmer AKEP series, Blemmer AE- 300, Blemmer ANE-1300, Blemmer PNEP series, Blemmer PNPE series, Blemmer 43ANEP 500, Bremer 70ANEP-550, etc .; Kyoeisha Chemical Co., Ltd. light ester MC, light ester 130MA, light ester 041MA, light acrylate BO-A, light acrylate EC-A, light acrylate MTG-A, light acrylate 130A, light acrylate DPM -A, light acrylate P-200A, light acrylate NP-4EA, light acrylate NP-8EA, and the like.

  As the polymer, a graft polymer using a so-called macromer can also be used. For example, it is described in “New Polymer Experimental Science 2, Synthesis and Reaction of Polymers” edited by Polymer Society of Japan, Kyoritsu Shuppansha (1995). It is also described in detail in Yuma Yamashita's “Chemical Monomer Chemistry and Industry” published by IPC (1989). Among the macromers, the useful molecular weight is in the range of 10,000 to 100,000, the preferred range is 10,000 to 50,000, and the particularly preferred range is in the range of 10,000 to 20,000. When the molecular weight is less than 10,000, the effect cannot be exhibited, and when it exceeds 100,000, the polymerizability with the copolymerization monomer forming the main chain is deteriorated. Specifically, Toagosei Co., Ltd. product: AA-6, AS-6S, AN-6S etc. can be used.

  Needless to say, the present invention is not limited to the above specific examples. The polyoxyalkylene group-containing ethylenically unsaturated monomer may be used alone or in combination of two or more.

  Other monomers specifically reacted with the above monomers include (meth) acrylic acid esters, (meth) acrylamides, allyl esters, allyloxyethanols, vinyl ethers, vinyl esters, dialkyl itaconate, fumaric acid And other mono (or di) alkyl esters, crotonic acid, itaconic acid, (meth) acrylonitrile, maleronitrile, styrene, and the like.

  Specific examples include the following compounds.

  Acrylic acid esters: methyl acrylate, ethyl acrylate, propyl acrylate, chloroethyl acrylate, 2-hydroxyethyl acrylate, trimethylolpropane monoacrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, etc. Methacrylic acid esters: methyl methacrylate, ethyl methacrylate, propyl methacrylate, chloroethyl methacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane monomethacrylate, benzyl methacrylate, methoxybenzyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, etc. Acrylamide: Acrylamide, N-alkylacrylamide Those having 1 to 3 carbon atoms as the alkyl group, for example methyl, ethyl, propyl), N, N- dialkyl acrylamide, N- hydroxyethyl -N- methylacrylamide, etc. N-2- acetamidoethyl -N- acetyl acrylamide. Further, as alkyloxyacrylamide, methoxymethylacrylamide, butoxymethylacrylamide, etc., methacrylamides: methacrylamide, N-alkylmethacrylamide, N-hydroxyethyl-N-methylmethacrylamide, N-2-acetamidoethyl-N-acetyl Allyl compounds: allyl esters (allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, acetoacetate), such as methacrylamide, methoxymethyl methacrylate, butoxymethyl methacrylate Allyl, allyl lactate, etc.), allyloxyethanol, etc., vinyl ethers: alkyl vinyl ether (hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether) Tellurium, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether , Butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, etc.), vinyl esters: vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valate, vinyl caproate, vinyl chloroacetate, vinyl Dichloroacetate, vinyl methoxyacetate Over DOO, vinyl butoxy acetate, vinyl lactate, vinyl -β- phenylbutyrate, vinyl cyclohexylcarboxylate, dialkyl itaconates: dimethyl itaconate, diethyl itaconate, itaconic acid dibutyl. Dialkyl esters or monoalkyl esters of fumaric acid: dibutyl fumarate, etc., crotonic acid, itaconic acid, acrylonitrile, methacrylonitrile, maleilonitrile, styrene, etc.

  In the case of introducing an amide group, a linear or branched alkyl group having 4 to 22 carbon atoms, an aromatic group, or a heterocyclic group having 5 or more members, among these monomers or other monomers, these functional groups A monomer containing can be selected. For example, 1-vinylimidazole or a derivative thereof can be used to introduce a heterocyclic group having 5 or more members. Furthermore, an isocyanate group or an epoxy group is previously introduced into the polymer, and these are reacted with an alcohol or an amine containing a linear or branched alkyl group, an aromatic group, or a 5- or more-membered heterocyclic group. Thus, various functional groups may be introduced into the polymer. In order to introduce isocyanate or epoxy, Karenz MOI (manufactured by Showa Denko) or Bremer G (manufactured by Nippon Oil & Fats Co., Ltd.) can be used. It is also preferable to introduce a urethane bond.

  Specific examples of the amphiphilic polymer for preparing silver halide grains used in the present invention are shown below, but the present invention is not limited thereto.

(Polymerization initiator)
As the polymerization initiator, an azo polymer polymerization initiator or an organic peroxide can be used. Examples of the azo polymer polymerization initiator include ABN-R (2,2′-azobisisobutyronitrile) and ABN-V (2,2′-azobis (2,4-dimethylvaleronitrile) manufactured by Nippon Hydrazine Kogyo Co., Ltd. )), ABN-E (2,2′-azobis (2-methylbutyronitrile)) and the like. Organic peroxides include bezoyl peroxide, dimethyl ethyl ketone peroxide, lauryl peroxide, Pertetra A, Perhexa HC, Perhexa TMH, Perhexa C, Perhexa V, Perhexa 22, Perhexa MC, Perbutyl H, manufactured by NOF Corporation. Parkmill H, Parkmill P, Permenta H, Perocta H, Perbutyl C, Perbutyl D, Perhexyl D, Parroyl IB, Parroyl 355, Parroyl L, Parroyl S, Parroyl SA, Nipper BW, Nipper BMT-K40, Nipper BMT-T40, Nipper BMT-M, Parroyl IPP, Parroyl NPP, Parroyl TCP, Parroyl EEP, Parroyl MBP, Parroyl OPP, Parroyl SBP, Parkmill ND, Parocta ND, Percyclo N Perhexyl ND, Perbutyl ND, Perhexyl PV, Perhexa 250, Perocta O, Perhexyl O, Perbutyl O, Perbutyl IB, Perbutyl L, Perbutyl 355, Perhexyl I, Perbutyl I, Perbutyl E, Perhexa 25Z, Perhexa 25MT, Perbutyl A, Perhexyl Z, perbutyl ZT, perbutyl Z, etc. are mentioned.

  Moreover, as a polymerization inhibitor, although a quinone type inhibitor is used, hydroquinone and p-methoxyphenol are mentioned. Seiko Chemical's phenothiazine, methoquinone, non-flex alba, MH (methylhydroquinone), TBH (t-butylhydroquinone), PBQ (p-benzoquinone), tolquinone, TBQ (t-butyl-p-benzoquinone), 2,5 diphenyl -P-benzoquinone etc. are mentioned.

  The isoelectric point of the polymer is preferably pH 6 or less. If a polymer having a high isoelectric point is used, as will be described later, when the silver halide grains are desalted by the aggregation precipitation method, the decomposition of the silver halide grains is promoted and the photographic performance is adversely affected. . Further, when silver halide fine particles are dispersed in a solvent, it is difficult to disperse unless the pH is raised, which is not preferable from the viewpoint of fogging. The isoelectric point of the polymer is measured, for example, by measuring the pH after isoelectric focusing or passing a 1% aqueous solution through a mixed bed column of cation and anion exchange resin.

  Various acidic groups can be introduced to lower the isoelectric point of the polymer. Examples include a carboxyl group and a sulfo group. In addition to using monomers of acrylic acid and methacrylic acid for introduction of the carboxyl group, it is also possible to partially obtain a polymer containing methyl methacrylate and the like. In addition to using styrenesulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid as a monomer, the carboxyl group can be introduced after the preparation of the polymer by various sulfation techniques. In particular, when a carboxylic acid is used, the solubility in a solvent is relatively high in an unneutralized state, and the property can be changed to water-soluble by neutralization or semi-neutralization, which is particularly preferable. Neutralization can also be performed with a sodium salt or a potassium salt, and organic salts such as ammonia, monoethanolamine, diethanolamine, and triethanolamine may be used. Imidazoles, triazoles, and amidoamines can also be used.

  The polymerization can be carried out in the presence or absence of a solvent, but is preferably in the presence of a solvent from the viewpoint of workability. Preferred solvents include alcohols such as ethanol, i-propyl alcohol, butanol, i-butanol and t-butanol, ketones such as acetone, methyl ethyl ketone, methyl-i-butyl ketone and methyl amyl ketone, methyl acetate and acetic acid. Esters such as ethyl, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, butyl 2-oxypropionate, 2-methoxypropion Monocarboxylic acid esters such as methyl acid, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, butyl 2-methoxypropionate, polar solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, methyl cello Ethers such as butyl, cellosolve, butyl cellosolve, butyl carbitol, ethyl cellosolve acetate, propylene glycols such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, and Its esters, halogen solvents such as 1,1,1-trichloroethane and chloroform, ethers such as tetrahydrofuran and dioxane, aromatics such as benzene, toluene and xylene, and fluorine such as perfluorooctane and perfluorotributylamine And inert liquids.

  Depending on the polymerizability of each monomer, a dropping polymerization method in which a monomer and an initiator are added dropwise to a reaction vessel is also effective for obtaining a polymer having a uniform composition. Unreacted monomer can be removed by removing it by column filtration, reprecipitation purification, solvent extraction or the like. Alternatively, low-boiling unreacted monomers can be removed by stripping.

[Silver ion reducing agent]
In the present invention, the photosensitive layer preferably contains a silver ion reducing agent.

  The reducing agent is preferably a bisphenol type reducing agent. For example, paragraph numbers “0043” to “0045” of JP-A-11-65021, page 7 line 34 to page 18 line 12 of European Patent Publication No. EP 0803764A1, paragraph numbers “0124” to “0133” of JP 2003-302723 A. , Paragraph numbers “0124” to “0127” of JP-A No. 2003-315954, and paragraph numbers “0042” to “0057” of JP-A No. 2004-4650.

  In the present invention, as a silver ion reducing agent, it is also a preferred embodiment to use a compound represented by the following general formula (1) alone or in combination with a reducing agent having another different chemical structure.

[Wherein, R ₁ represents a hydrogen atom or a substituent, and R ₂ and R ₃ each represents an alkyl group having 1 to 8 carbon atoms. A ₁ and A ₂ each represent a hydroxyl group or a group that can be deprotected to form a hydroxyl group, and m and n each represent an integer of 1 to 5. ]
In the general formula (1), R ₁ represents a hydrogen atom or a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a halogen atom, and a cyano group. Preferably, they are a hydrogen atom, an alkyl group, a cycloalkyl group, or an alkenyl group, More preferably, they are a hydrogen atom or an alkyl group. These substituents may further have a substituent, such as an alkyl group, a cycloalkyl group, a halogenated alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a halogen atom, Cyano group, hydroxyl group, carboxyl group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, anilino group, acylamino group , Aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group Alkyl and arylsulfinyl groups, alkyl and arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, carbamoyl groups, aryl and heterocyclic azo groups, imide groups, silyl groups, hydrazino groups, ureido groups, boronic acid groups, Examples thereof include a phosphato group, a sulfato group, and other known substituents.

R ₂ and R ₃ each represent an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, t-butyl group, t-amyl group, i-propyl group, i-butyl group, i-propyl group, 1, 1-dimethylbutyl group, 1-methylcyclopentyl group, 1-methylcyclobutyl group, 1-methylcyclopropyl group, 1-methylbutyl group, 1,3-dimethylbutyl group, 1-methylpropyl group, 1,1,2 -A trimethylpropyl group, 1-ethyl-1-methylpropyl group, etc. are mentioned. A t-butyl group, a 1,1-dimethylbutyl group or a t-amyl group is preferable, and a t-butyl group is more preferable. These alkyl groups may further have a substituent, and examples of the substituent include a hydroxyl group, a cyano group, a mercapto group, a halogen atom, an amino group, an imide group, a silyl group, and a hydrazino group.

A ₁ and A ₂ each represent a hydroxyl group or a group that can be deprotected to form a hydroxyl group, and is preferably a hydroxyl group. Examples of the group that can be deprotected to form a hydroxyl group include a group that decomposes and leaves by the action of an acid and / or heat to form a hydroxyl group. Specifically, ether groups (methoxy, t-butoxy, allyloxy, benzyloxy, triphenylmethoxy, trimethylsilyloxy, etc.), hemiacetal groups (tetrahydropyranyloxy, etc.), ester groups (acetyloxy, benzoyloxy, p- Nitrobenzoyloxy, formyloxy, trifluoroacetyloxy, pivaloyloxy, etc.), carbonate groups (ethoxycarbonyloxy, phenoxycarbonyloxy, t-butyloxycarbonyloxy, etc.), sulfonate groups (p-toluenesulfonyloxy, benzenesulfonyloxy, etc.) Carbamoyloxy group (phenylcarbamoyloxy etc.), thiocarbonyloxy group (benzylthiocarbonyloxy etc.), nitrate ester group, sulfenate group (2,4-dinitrobe Zen sulfenyl oxy, etc.). m and n each represents an integer of 1 to 5, preferably 2 or 3.

The structures of the substituents R ₁ , R ₂ , R ₃ , A ₁ and A ₂ exemplified above are one of the factors that determine the thermal properties and crystallinity of the bisphenol type reducing agent. In imaging materials, the melting point, thermal decomposition temperature, and crystallinity of the reducing agent are greatly correlated with photographic performance.

  When used in the silver salt photothermographic dry imaging material according to the present invention, the melting point is preferably 80 to 250 ° C. and the thermal decomposition temperature is preferably 200 ° C. or higher. Silver salt photothermographic dry imaging materials in which the reducing agent remains in the light-sensitive material after development processing are less fogged due to the reduction reaction during image storage because the highly crystalline reducing agent suppresses material diffusion during storage. Therefore, it is more preferable that the crystallinity of the reducing agent is higher.

  Although the specific example of a reducing agent represented by General formula (1) below is shown, this invention is not limited to these.

  The reducing agent 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 silver salt photothermographic dry imaging material.

  In the present invention, U.S. Pat. Nos. 3,589,903, 4,021,249, British Patent 1,486,148, and JP-A-51-51933, JP-A-50-36110, JP-A-50-116033. 52-84727 or JP-B-51-35727, such as 2,2'-dihydroxy-1,1'-binaphthyl, 6,6'-dibromo-2,2'-dihydroxy-1 Bisnaphthols described in U.S. Pat. No. 3,672,904 such as 1,1'-binaphthyl and the like, and further, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfone As described in US Pat. No. 3,801,321 such as amidophenol, 4-benzenesulfonamidonaphthol and the like Sulfonamidophenols or sulfonamide naphthols can also be used as the silver ion reducing agent.

  The amount of the reducing agent used varies depending on the type of the aliphatic carboxylic acid silver salt, the reducing agent, and other additives, but generally 0.05 to 10 mol, preferably 1 mol per mol of the aliphatic carboxylic acid silver salt. 0.1-3 mol is suitable. In the present invention, the reducing agent is added to and mixed with a photosensitive emulsion solution consisting of photosensitive silver halide grains, aliphatic carboxylic acid silver salt grains and a solvent immediately before coating, and the method of coating the liquid is a variation in photographic performance due to stagnation time. May be preferable in some cases.

[Binder resin]
In the silver salt photothermographic dry imaging material, a photosensitive resin and a non-photosensitive layer can contain a binder resin (hereinafter, also abbreviated as “binder” or simply “resin”) for various purposes.

  The binder resin contained in the photosensitive layer according to the present invention can carry an aliphatic carboxylic acid silver salt, silver halide grains, a reducing agent, and other components, and the binder preferably used is transparent or translucent. In general, it is colorless and includes natural polymers, synthetic polymers and copolymers, and other media for forming a film, for example, those described in paragraph “0069” of JP-A No. 2001-330918. Among these, methacrylic acid alkyl esters, methacrylic acid aromatic esters, styrenes and the like are particularly preferred examples. 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. Preferred binders for the present invention are polyvinyl acetals, particularly preferably polyvinyl butyral, and is preferably used as the main binder of the photosensitive layer. 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.

  In the present invention, the degree of polymerization of the binder resin is preferably 700 to 3000, more preferably 1000 to 3000. When it is less than 700, the strength of the photosensitive layer is inferior, and when it exceeds 3000, dispersibility and applicability are inferior. In particular, the polyvinyl acetal resin having a degree of polymerization of 1000 to 3000 has the effect that low fog and high maximum density can be obtained even in short-time heat development, and there is almost no increase in fog during storage. Is done.

  The polyvinyl acetal resin preferably has a residual acetyl group content of 25 mol% or less. If the amount of residual acetyl groups exceeds 25 mol%, silver salt photothermographic dry imaging materials may stick to each other (blocking) or the sharpness of the image may deteriorate. More preferably, it is 15 mol% or less.

  The polyvinyl acetal resin preferably has a residual hydroxyl group content of 15 to 35 mol%. If it is less than 15 mol%, the dispersibility of the aliphatic carboxylic acid silver salt may deteriorate and the sensitivity may decrease. If it exceeds 35 mol%, the water content of the silver salt photothermographic dry imaging material will increase, and fog may deteriorate or storage stability may deteriorate. More preferably, it is 15-25 mol%.

The glass transition temperature (T _g ) of the binder resin will be described. T _g of the binder resin is a value which is a measure of the thermal phase transition temperature in the interior of each layer, the variation and the photographic properties due to diffusion of the material during storage and T _g is too low, the concentration change after heat development accelerator This is not preferable. Further, T _g can not optimize resin flow resistance at high temperatures, such as too high drying temperature and the thermal development temperatures. This is not preferable because the drying rate of the coating solution solvent is reduced during drying, and the diffusion rate of a material necessary for image formation is reduced during development. From the above, T _g of the binder resin in the photosensitive layer according to the present invention is preferably 65 to 95 ° C.. By T _g is optimized, sufficient fog density in the image formation is preferable in that it can maximum density obtained.

  For non-image forming layers (non-photosensitive layers) such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters that are polymers with higher softening temperatures, especially triacetyl cellulose, cellulose acetate butyrate Polymers such as rate are preferred. If necessary, two or more binder resins may be used in combination as described above.

These binder resins are used in an effective range to function as a binder for fixing the elements of each layer. The effective range can be easily determined by one skilled in the art. For example, as an index for holding at least an aliphatic carboxylic acid silver salt in the photosensitive layer, the ratio of the binder to the aliphatic carboxylic acid silver salt is preferably 15: 1 to 1: 2 (mass ratio), particularly 8 : The range of 1-1: 1 is preferable. 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.

[Crosslinking agent]
The photosensitive layer may contain a cross-linking agent that can link the binders together by bridging bonds. 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.

  As the crosslinking agent used, various crosslinking agents conventionally used for ordinary photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based compounds described in JP-A No. 50-96216 are used. Sulfonic acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based cross-linking 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), specifically, aliphatic diisocyanates, aliphatic diisocyanates having a cyclic group, and benzene diisocyanates. , Naphthalene diisocyanates, biphenyl diisocyanates, diphenylmethane diisocyanates, triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates and diisocyanates with di- or trivalent polyalcohols Examples include adducts. 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 contained in any part of the silver salt photothermographic dry imaging material. For example, in the support (especially when the support is paper, it can be included in the size composition), image forming layer (photosensitive layer), surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer on the photosensitive layer side of the support, and can be added to one or more of these layers.

  As usable thioisocyanate-based crosslinking agents, 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.

  The epoxy compound that can be used as a crosslinking agent is not particularly limited as long as it has one or more epoxy groups and the number of epoxy groups, molecular weight, and the like. 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.

In addition, as the crosslinking agent used in the present invention, any crosslinking agent that can react with a hydroxyl group or a carboxyl group can be preferably used. Examples thereof include an acid anhydride, an oxazoline compound, and a carbodiimide compound. A crosslinking agent 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. Moreover, it is preferable that it is 0.5-200 mass parts with respect to 100 mass parts of binders of the component layer contained, 2-100 mass parts is more preferable, Furthermore, 3-50 mass parts is especially preferable. This epoxy compound or acid anhydride can be added to any layer on the image forming layer side of the support, such as an image forming layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. It can be added to one layer or two or more layers. When added to the image forming layer, if accompanied by the progress of the crosslinking reaction and the decrease in developability, adding more to the layer closer to the support than the image forming layer, without impairing the developability, with film (adhesiveness) ), Development unevenness can be improved.

  The cross-linking agent used in the present invention may be added in a state of being premixed in the binder solution, may be added at the end of the preparation process of the coating solution, or may be added immediately before coating.

[Chemical sensitization, spectral sensitization, supersensitization]
The photosensitive silver halide grains can be chemically sensitized. For example, by a method described in JP-A Nos. 2001-249428 and 2001-249426, a compound that releases chalcogen such as sulfur, selenium, and tellurium, and a noble metal compound that releases noble metal ions such as gold ions can be used for photosensitivity. It is possible to form and impart a chemical sensitization center (chemical sensitization nucleus) capable of capturing electrons or holes generated by photoexcitation of the light-sensitive silver halide grains or the spectral sensitizing dye on the grains. 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 being adsorbed on silver halide grains and unstable chalcogen atom sites. These organic sensitizers are disclosed in 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. Organic sensitizers having various structures can be used, and of these, 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 preferred. In particular, a thiourea derivative having a heterocyclic group and a triphenylphosphine sulfide derivative are preferred. As a method for performing chemical sensitization, techniques according to various chemical sensitization techniques conventionally used in the production of conventional silver halide light-sensitive materials for wet processing can be used (edited by TH James “ The Theory of the Photographic Process, 4th edition, McCillall Publishing Publishing Co., Ltd. (1977), edited by the Japan Photography Society, “Basics of Photographic Engineering (Silver Salt Photography)” Corona (1979)). In particular, when the silver halide grain emulsion is previously chemically sensitized and then mixed with non-photosensitive aliphatic carboxylic acid silver salt grains, it can be chemically sensitized by a conventional method.

The amount of the chalcogen compound used as the organic sensitizer varies depending on the chalcogen compound used, silver halide grains, reaction environment for chemical sensitization, etc., but is 10 ⁻⁸ to 10 ⁻ per mol of silver halide. ² mol is preferred, more preferably 10 ⁻⁷ to 10 ⁻³ mol.

  There are no particular restrictions on the environmental conditions for chemical sensitization, but in the presence of a compound capable of eliminating or reducing the size of silver chalcogenide or silver nuclei on the photosensitive silver halide grains. In particular, it may be preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei. The sensitizing conditions in this case are preferably 6 to 11 as pAg, more preferably 7 to 10, pH 4 to 10 is more preferable, 5 to 8 is more preferable, and temperature is 30 ° C. or less. It is preferable to perform sensitization.

  Chemical sensitization using these organic sensitizers is preferably carried out in the presence of a heteroatom-containing compound having adsorptivity to spectral sensitizing dyes or silver halide grains. By performing chemical sensitization in the presence of a compound having adsorptivity to silver halide grains, dispersion of the chemically sensitized central core can be prevented, and high sensitivity and low fog can be achieved. Although a spectral sensitizing dye will be described later, a nitrogen-containing heterocyclic compound described in JP-A-3-24537 is a preferred example of a heteroatom-containing compound having adsorptivity to silver halide grains. In the nitrogen-containing heterocyclic compound, examples of the heterocyclic ring include pyrazole, pyrimidine, 1,2,4-triazole, 1,2,3-triazole, 1,3,4-thiadiazole, 1,2,3-thiadiazole, 1 , 2,4-thiadiazole, 1,2,5-thiadiazole, 1,2,3,4-tetrazole, pyridazine, 1,2,3-triazine ring, a ring in which two or three of these rings are bonded, for example, tria Examples include zolotriazole, diazaindene, triazaindene, pentazaindene ring and the like. A heterocyclic ring in which a monocyclic heterocyclic ring and an aromatic ring are condensed, for example, phthalazine, benzimidazole, indazole, benzthiazole ring and the like can also be applied.

  Among these, an azaindene ring is preferable, and an azaindene compound having a hydroxyl group as a substituent, such as a hydroxytriazaindene, tetrahydroxyazaindene, hydroxypentazaindene compound, or the like is more preferable.

  The heterocyclic ring may have a substituent other than the hydroxyl group. Examples of the substituent include an alkyl group, a substituted alkyl group, an alkylthio group, an amino group, a hydroxyamino group, an alkylamino group, a dialkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, a halogen atom, and a cyano group. You may have.

The addition amount of these heterocyclic compounds varies over a wide range depending on the size, composition and other conditions of the silver halide grains, but the approximate amount is 10 ⁻⁶ to 1 mol per mol of silver halide. And preferably in the range of 10 ⁻⁴ to 10 ⁻¹ mol.

  The photosensitive silver halide grains can be subjected to noble metal sensitization using a compound that releases noble metal ions such as gold ions. For example, a chloroaurate or an organic gold compound can be used as a gold sensitizer. The gold sensitization technique disclosed in JP-A-11-194447 is useful as a reference.

  In addition to the above sensitization methods, reduction sensitization methods and the like can also be used, and as a shell-like compound for reduction sensitization, ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, borane compounds, Silane compounds, polyamine compounds, and the like can be used. Further, reduction sensitization can be performed by ripening the emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower.

  In the present invention, the silver halide grains subjected to chemical sensitization were formed in the absence of the aliphatic carboxylic acid silver salt even though they were formed in the presence of the aliphatic carboxylic acid silver salt. However, both may be mixed.

  When the surface of the photosensitive silver halide grain is chemically sensitized, it is preferable that the effect of the chemical sensitization substantially disappears after the thermal development process. Here, the chemical sensitization effect substantially disappears when the sensitivity of the imaging material obtained by the chemical sensitization technique is 1.1 when the chemical sensitization is not performed after the thermal development process. Say to decrease to less than double. In order to eliminate the chemical sensitization effect in the thermal development process, an oxidant capable of destroying the chemical sensitization center (chemical sensitization nucleus) by an oxidation reaction at the time of thermal development, such as a halogen radical releasing compound described later, etc. It is necessary to contain an appropriate amount 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.

  The photosensitive silver halide grain is preferably subjected to spectral sensitization by adsorbing a spectral sensitizing dye. As spectral sensitizing dyes, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes and the like can be used. For example, JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242, 63-15245, U.S. Pat. Nos. 4,639,414, 4 , 740,455, 4,741,966, 4,751,175, and 4,835,096 can be used.

  Useful sensitizing dyes used in the present invention are described in, for example, Research Disclosure (hereinafter abbreviated as RD) 17643IV-A (December 23, 1978), RD18431X (August 1978, 437) or It is described in the cited literature. In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various laser imagers and scanner light sources. For example, compounds described in JP-A Nos. 9-34078, 9-54409, and 9-80679 are preferably used.

  Useful cyanine dyes are cyanine dyes having basic nuclei such as thiazoline nucleus, oxazoline nucleus, pyrroline nucleus, pyridine nucleus, oxazole nucleus, thiazole nucleus, selenazole nucleus and imidazole nucleus. Useful merocyanine dyes are preferably acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus in addition to the basic nuclei described above. Including.

  In the present invention, a sensitizing dye having spectral sensitivity particularly in the infrared can also be used. Examples of infrared spectral sensitizing dyes preferably used include infrared spectral sensitizing dyes disclosed in U.S. Pat. Nos. 4,536,473, 4,515,888, and 4,959,294. It is done.

  The silver salt photothermographic dry imaging material of the present invention is represented by the following general formula (SD1) and the following general formula (SD2) as described in JP-A No. 2004-309758. It is preferable to contain at least one selected from sensitizing dyes.

In the formula, Y ₁ and Y ₂ each represent an oxygen atom, a sulfur atom, a selenium atom or a —CH═CH— group, and L _{1 to} L ₉ each represent a methine group. R ₁ and R ₂ each represents an aliphatic group. R ₃ and R ₄ each represent a lower alkyl group, a cycloalkyl group, an alkenyl group, an aralkyl group, an aryl group, or a heterocyclic group. W ₁ , W ₂ , W ₃ , and W ₄ are each a hydrogen atom, a substituent, or a nonmetallic atom necessary for bonding between W ₁ and W ₂ , W ₃ and W ₄ to form a condensed ring. Represents a group. Alternatively, R ₃ and W ₁ , R ₃ and W ₂ , R ₄ and R ₃ , R ₄ and W ₄ are bonded to each other to represent a group of nonmetallic atoms necessary to form a 5- or 6-membered condensed ring. . X ₁ represents an ion necessary to cancel the charge in the molecule, and k ₁ represents the number of ions necessary to cancel the charge in the molecule. m ₁ represents 0 or 1, and n ₁ and n ₂ each represents 0, 1 or 2. However, n ₁ and n ₂ are not 0 at the same time.

  The above-mentioned infrared sensitizing dyes are described, for example, by HM Hammer: The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanine Dies and Related Compounds (A. Weissberger Ed. Interscience, New York (1964)).

  These infrared sensitizing dyes may be added at any time after the silver halide grains are prepared. For example, they are added to a solvent or dispersed in the form of fine particles, so-called silver halide grains or halogenated grains in a so-called solid dispersion state. It can be added to a photosensitive emulsion containing silver particles / silver aliphatic carboxylic acid salt particles. Similarly to the heteroatom-containing compound having adsorptivity to the silver halide grains, chemical sensitization can be performed after adding and adsorbing to the silver halide grains prior to chemical sensitization. Can prevent dispersion of chemically sensitized nuclei, and can achieve high sensitivity and low fog.

  The above spectral sensitizing dyes may be used alone, but as described above, it is preferable to use a combination of a plurality of types of spectral sensitizing dyes. Often used for purposes such as supersensitization and expansion or adjustment of the photosensitive wavelength region.

  Emulsions containing photosensitive silver halide grains and aliphatic carboxylic acid silver salts used in silver salt photothermographic dry imaging materials, together with sensitizing dyes, are substantially free of spectral sensitizing dyes or visible light. In the emulsion, a substance that does not absorb light and exhibits a supersensitizing 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), Section J, page 23, or Japanese Patent Publication No. 9-25500. No. 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like, but as a supersensitizer, a heteroaromatic mercapto compound represented by the following is used. Or a mercapto derivative compound is preferable.

Ar-SM
In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. Preferred heteroaromatic rings are preferably benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine , Purine, quinoline, or quinazoline. However, other heteroaromatic rings are also included.

  In addition, a mercapto derivative compound which substantially forms the above mercapto compound when contained in a dispersion of an aliphatic carboxylic acid silver salt or a silver halide grain emulsion is also included. In particular, mercapto derivative compounds represented below are preferred examples.

Ar-SS-Ar
In the formula, Ar has the same meaning as in the case of the mercapto compound represented above.

  The heteroaromatic ring is, for example, a halogen atom (chlorine, bromine, iodine), a hydroxyl group, an amino group, a carboxyl group, or an alkyl group (having one or more carbon atoms, preferably having 1 to 4 carbon atoms). And a substituent selected from the group consisting of alkoxy groups (having one or more carbon atoms, preferably 1 to 4 carbon atoms).

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

  The supersensitizer is preferably used in an amount of 0.001 to 1.0 mol per mol of silver in the photosensitive layer containing the aliphatic carboxylic acid silver salt and silver halide grains. Most preferably, it is 0.01-0.5 mol per 1 mol of silver.

  In the present invention, it is preferable that spectral sensitization is performed by adsorbing a spectral sensitizing dye on the surface of photosensitive silver halide grains, and that the spectral sensitization effect substantially disappears after the thermal development process. . Here, the spectral sensitization effect substantially disappears when the sensitivity of the imaging material obtained with a sensitizing dye, supersensitizer, etc. is 1 when the spectral sensitization is not performed after the thermal development. It means to decrease to 1 times or less.

  In order to eliminate the spectral sensitization effect in the thermal development process, a spectral sensitizing dye that is easily detached from the silver halide grains by heat is used during thermal development or / and the spectral sensitizing dye is destroyed by an oxidation reaction. It is necessary to contain an appropriate amount of an oxidizing agent that can be formed, for example, a halogen radical releasing compound described later, 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.

[Color tone adjuster]
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, it is said that the warm image tone is a warm black tone with a brown image. For the sake of more precise quantitative discussion, the International Lighting Commission (CIE) ), Based on the recommended expression.

The terms “more cold” and “more warm” with respect to the color tone can be expressed by a hue angle hab at a minimum density (D _min ) and an optical density of 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.

(Formula) hab = tan ⁻¹ (b ^* / a ^* )
As a result of examination by the expression method based on the hue angle, the color tone after thermal development of the silver salt photothermographic dry imaging material of the present invention is preferably such that the range of the hue angle hab is 180 degrees <hab <270 degrees, It was found that preferably 200 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 having a favorable color tone can be obtained by adjusting the numerical value, and is described in, for example, Japanese Patent Application Laid-Open No. 2000-29164.

However, as a result of further intensive studies on silver salt photothermographic dry imaging materials, the horizontal axis in the CIE 1976 (L ^* u ^* v ^* ) color space or (L ^* a ^* b ^* ) color space is u ^* or a ^* , When plotting u ^* , v ^* or a ^* , b ^* at various photographic densities on a graph with the axis as v ^* or b ^* and creating a linear regression line, the linear regression line is specified. It was found that by adjusting to the range, it has a diagnostic property equal to or higher than that of a conventional wet silver salt photosensitive material. A preferable range of conditions is described below.

(1) A silver salt photothermographic dry imaging material is color-measured for each of the optical densities of 0.5, 1.0, 1.5 and the lowest optical density of a silver image obtained after 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 ^*. Heavy 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) The color density of each of the optical densities 0.5, 1.0, 1.5 and the lowest optical density of the photothermographic dry imaging material is measured, and the CIE 1976 (L ^* a ^* b ^* ) color space is measured. The coefficient of determination (multiple determination) R ^{2 of} the linear regression line created by arranging a ^* and b ^* at the respective optical densities on two-dimensional coordinates with the horizontal axis a ^* and the vertical axis b ^* is 0.998. It is preferably ˜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.

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 CIE 1976 color space will be described next.

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 (manufactured by Konica Minolta: CM-3600d, etc.), and u ^* , v ^* or a ^* , b ^* are calculated. The measurement conditions at that time are F7 light source as the light source, the viewing angle is 10 degrees, and the measurement is performed in the transmission measurement mode. Plot u ^* , v ^* or a ^* , b ^* measured on a graph with u ^* or a ^{* on} the horizontal axis and v ^* or b ^{* on the} vertical axis to obtain a linear regression line, and the coefficient of determination (multiple determination) Find R ² , intercept and slope.

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

  In the present invention, by adjusting the addition amount of a compound or the like directly or indirectly involved in the development reaction process such as silver ion reducing agent, silver halide grains, aliphatic carboxylic acid silver salt and the following toning agent. 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 are disclosed in RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, 4,021,249, and the like.

  In addition to such a toning agent, the color tone is adjusted using couplers disclosed in JP-A-11-288057, European Patent 1,134,611A2, etc., and leuco dyes described in detail below. You can also. In particular, a coupler or leuco dye is preferably used for fine adjustment of the color tone.

  The silver salt photothermographic dry imaging material can also be adjusted in color tone using a leuco dye as described above. 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 to 200 ° C. for about 0.5 to 30 seconds, and is a silver ion reducing agent as described above. Any leuco dye that is oxidized by an oxidant or the like to form a pigment can be used. Also useful are compounds that are pH sensitive and can be oxidized to a colored state.

  Representative leuco dyes suitable for use in the present invention are not particularly limited and include, for example, biphenol leuco dyes, phenol leuco dyes, indoaniline leuco dyes, acrylated azine leuco dyes, phenoxazine leuco dyes, phenodiazine leuco dyes and And phenothiazine leuco dye. US Pat. Nos. 3,445,234, 3,846,136, 3,994,732, 4,021,249, 4,021,250, 4,022 are useful. No. 4,617, No. 4,123,282, No. 4,368,247, No. 4,461,681, and JP-A-50-36110, JP-A-52-206831, JP-A-5-204087, No. 11-231460, JP-A Nos. 2002-169249, 2002-236334, and the like.

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination. In the present invention, with the use of a highly active silver ion reducing agent, the color tone (especially yellowishness) varies depending on the amount and ratio of use, or the use of fine silver halide grains makes it particularly effective. In order to prevent the image from becoming excessively reddish at a high density portion of 2.0 or more, it is preferable to use a leuco dye that develops yellow and cyan colors 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, color is developed 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, and the color tone is adjusted so that an image in the above preferred color tone range is obtained. Is preferred. The sum of the maximum densities at the maximum absorption wavelength of the dye image formed by the leuco dye is preferably 0.01 to 0.50, more preferably 0.02 to 0.30, and particularly preferably 0.03 to 0. It is preferable to develop the color so as to have.

(Yellow coloring leuco dye)
The silver salt photothermographic dry imaging material can also be adjusted in color tone using a leuco dye as described above. In the present invention, a color image forming agent whose absorbance at 360 to 450 nm is increased by oxidation is preferably used as the yellow color-forming leuco dye. These color image forming agents are particularly preferably color image forming agents represented by the following general formula (YA).

In the formula, R ₁₁ represents a substituted or unsubstituted alkyl group, R ₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an acylamino group, and R ₁₁ and R ₁₂ are 2-hydroxyphenylmethyl groups. There is nothing. R ₁₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₁₄ represents a substituent that can be substituted on the benzene ring.

R ₁₁ represents a substituted or unsubstituted alkyl group. When R ₁₂ is a substituent other than a hydrogen atom, R ₁₁ represents an alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms and may have a substituent. Specifically, methyl, ethyl, butyl, octyl, i-propyl, t-butyl, t-octyl, t-pentyl, sec-butyl, cyclohexyl, 1-methyl-cyclohexyl and the like are preferred, and steric rather than i-propyl. Is preferably a large group (i-propyl, i-nonyl, t-butyl, t-amyl, t-octyl, cyclohexyl, 1-methyl-cyclohexyl, adamantyl, etc.), and among them, secondary or tertiary An alkyl group is preferable, and tertiary alkyl groups such as t-butyl, t-octyl, and t-pentyl are particularly preferable. Examples of the substituent that R ₁₁ may have include a halogen atom, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamido group, an acyloxy group, an oxycarbonyl group, and a carbamoyl group. , Sulfamoyl group, sulfonyl group, phosphoryl group and the like.

R ₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an acylamino group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, and the acylamino group is preferably an acylamino group having 1 to 30 carbon atoms. Among these, the description of the alkyl group is the same as R ₁₁ described above. The acylamino group may be unsubstituted or substituted, and specific examples include an acetylamino group, an alkoxyacetylamino group, and an aryloxyacetylamino group. R ₁₂ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include methyl, i-propyl, and t-butyl.

R ₁₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, and the description of the alkyl group is the same as that for R ₁₁ . R ₁₃ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include methyl, i-propyl, t-butyl and the like. Further, it is preferable either R _12, R ₁₃ is a hydrogen atom.

R ₁₄ represents a group capable of substituting on the benzene ring, specifically, an alkyl group having 1 to 25 carbon atoms (methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl, cyclohexyl, etc.), halogenated Alkyl groups (trifluoromethyl, perfluorooctyl, etc.), cycloalkyl groups (cyclohexyl, cyclopentyl, etc.), alkynyl groups (propargyl etc.), glycidyl groups, acrylate groups, methacrylate groups, aryl groups (phenyl etc.), heterocyclic groups ( Pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl, pyrimidinyl, pyridazinyl, selenazolyl, sriphoranyl, piperidinyl, pyrazolyl, tetrazolyl, etc.), halogen atom (chlorine, bromine, iodine, fluorine), alkoxy group (methoxy, ethoxy, pro Ruoxy, pentyloxy, cyclopentyloxy, hexyloxy, cyclohexyloxy, etc.), aryloxy groups (phenoxy, etc.), alkoxycarbonyl groups (methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl, etc.), aryloxycarbonyl groups (phenyloxycarbonyl) ), Sulfonamide groups (methanesulfonamide, ethanesulfonamide, butanesulfonamide, hexanesulfonamide group, cyclohexanesulfonamide, benzenesulfonamide, etc.), sulfamoyl groups (aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl, butylamino) Sulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pyridylaminos Phonyl etc.), urethane groups (methylureido, ethylureido, pentylureido, cyclohexylureido, phenylureido, 2-pyridylureido etc.), acyl groups (acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl etc.), Carbamoyl group (aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl group, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl), amide group (acetamide, propionamide, butanamide, hexaneamide, Benzamide, etc.), sulfonyl groups (methylsulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexylsulfonyl, fluorine Phenylsulfonyl, 2-pyridylsulfonyl, etc.), amino group (amino, ethylamino, dimethylamino, butylamino, cyclopentylamino, anilino, 2-pyridylamino, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, An oxamoyl group can be exemplified. These groups may be further substituted with these groups.

R ₁₄ is preferably a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms or an oxycarbonyl group having 2 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Examples of the substituent of the alkyl group include an aryl group, an amino group, an alkoxy group, an oxycarbonyl group, an acylamino group, an acyloxy group, an imide group, and a ureido group, and more preferable examples include an aryl group, an amino group, an oxycarbonyl group, and an alkoxy group. preferable. These alkyl group substituents may be further substituted with these substituents.

  Next, the bisphenol compound represented by the following general formula (YB), which is particularly preferably used in the present invention, among the compounds represented by the general formula (YA) will be described.

In the formula, Z represents —S— or —C (R ₂₁ ) (R ₂₁ ′) —, and R ₂₁ and R ₂₁ ′ each represents a hydrogen atom or a substituent. Examples of substituents represented by R ₂₁ and R ₂₁ ′ include halogen atoms (fluorine, chlorine, bromine, etc.), alkyl groups (methyl, ethyl, propyl, butyl, pentyl, i-pentyl, 2-ethylhexyl, octyl, decyl, etc.) Cycloalkyl group (cyclohexyl, cycloheptyl etc.), alkenyl group (ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl etc.), cycloalkenyl group (1-cycloalkenyl, 2-cycloalkenyl group etc.), alkynyl group (ethynyl, 1-propynyl etc.), alkoxy group (methoxy, ethoxy, propoxy etc.), alkylcarbonyloxy group (acetyloxy etc.), alkylthio group (methylthio) , Trifluoromethylthio, etc.), acyl group (acetyl group, benzoy Group), carboxyl group, alkylcarbonylamino group (acetylamino etc.), ureido group (methylaminocarbonylamino etc.), alkylsulfonylamino group (methanesulfonylamino etc.), alkylsulfonyl group (methanesulfonyl, trifluoromethanesulfonyl etc.), Carbamoyl group (carbamoyl, N, N-dimethylcarbamoyl, N-morpholinocarbonyl, etc.), sulfamoyl group (sulfamoyl, N, N-dimethylsulfamoyl, morpholinosulfamoyl etc.), trifluoromethyl group, hydroxyl group, nitro group Cyano group, alkylsulfonamide group (methanesulfonamide, butanesulfonamide, etc.), alkylamino group (amino, N, N-dimethylamino, N, N-diethylamino, etc.), sulfo group, phosphono group, sa Rufite group, sulfino group, alkylsulfonylaminocarbonyl group (methanesulfonylaminocarbonyl, ethanesulfonylaminocarbonyl, etc.), alkylcarbonylaminosulfonyl group (acetamidosulfonyl, methoxyacetamidosulfonyl, etc.), alkynylaminocarbonyl group (acetamidocarbonyl, methoxyacetamidocarbonyl) Etc.), alkylsulfinylaminocarbonyl groups (methanesulfinylaminocarbonyl, ethanesulfinylaminocarbonyl, etc.) and the like. R ₂₁ and R ₂₁ ′ are preferably a hydrogen atom or an alkyl group.

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ each represent a substituent, for example, halogen atoms such as fluorine, chlorine and bromine, alkyl groups, hydroxyl groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups Group, aryl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, amino group, acyl group, acyloxy group, acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, sulfonyl group, alkylsulfonyl group, sulfinyl group , A cyano group, a heterocyclic group, and the like.

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, but an alkyl group is more preferable. Examples of the substituent on the alkyl group include the same groups as those described above. R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ are more preferably tertiary alkyl groups such as t-butyl, t-pentyl, t-octyl and 1-methyl-cyclohexyl.

R ₂₄ and R ₂₄ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as those described in the description of R ₁₄ above.

  Examples of the compounds represented by the general formulas (YA) and (YB) include compounds II-1 to II-40 described in paragraphs “0032” to “0038” of JP-A No. 2002-169249, European Patents 1 and 211. , 093, and the compounds ITS-1 to ITS-12 described in paragraph “0026”.

  Although the specific example of the bisphenol compound represented by general formula (YA) and (YB) below is shown, this invention is not limited to these.

  The addition amount of the compound of the general formula (YA) (including the hindered phenol compound and the compound of the general formula (YB)) is usually 0.00001 to 0.01 mol, preferably 0.0005, per mol of silver. It is -0.01 mol, More preferably, it is 0.001-0.008 mol.

  Moreover, the addition ratio of the yellow color-forming leuco dye to the sum of the reducing agents is preferably 0.001 to 0.2, more preferably 0.005 to 0.1 in terms of molar ratio.

(Cyan coloring leuco dye)
The silver salt photothermographic dry imaging material of the present invention can also be adjusted in color tone by using a cyan coloring leuco dye in addition to the yellow coloring leuco dye. The cyan chromophoric 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 forms a pigment by oxidation with an oxidant of the agent can be used. Compounds that are pH sensitive and can be oxidized to a colored state are useful.

What is preferably used as the cyan color-forming leuco dye is a color image forming agent that increases its absorbance at 600 to 700 nm when oxidized. Examples of these compounds include compounds of general formulas (I) to (IV) described in JP-A No. 59-206831 (particularly compounds having λ _max in the range of 600 to 700 nm) and JP-A No. 5-204087. Specifically, the compounds of (1) to (18) described in paragraphs “0032” to “0037”) and the compounds of general formulas 4 to 7 in JP-A No. 11-231460 (specifically, described in paragraph “0105”). Compound No. 1 to No. 79).

  The cyan color-forming leuco dye preferably used in the present invention is a compound represented by the following general formula (CLA) or general formula (CLB-I). The color image forming agent represented by the general formula (CLB-I) is particularly preferable in that it has high color development efficiency, can be adjusted in color even when added in a small amount, and is excellent in image storage stability.

  Hereinafter, the compounds of general formula (CLA) and general formula (CLB-I) will be described in detail.

In the formula, R ₃₁ and R ₃₂ represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, —NHCOR ₃₀ group (R ₃₀ represents an alkyl group, an aryl group, or a heterocyclic group). Or R ₃₁ and R ₃₂ are a group that forms an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, or a heterocyclic ring by being linked to each other. A ₃ represents a —NHCO— group, a —CONH— group or a —NHCONH— group, and R ₃₃ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. -A ₃ R ₃₃ may be a hydrogen atom. For example, the —A ₃ R ₃₃ moiety represents a hydrogen atom, or A ₃ represents a —NHCO— group, —CONH— group, or —NHCONH— group, and R ₃₃ represents a substituted or unsubstituted alkyl group, aryl group, or Represents a heterocyclic group.

W ₃ represents a hydrogen atom or —CONHR ₃₅ group, —COR ₃₅ group or —COOR ₃₅ group (R ₃₅ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group), and R ₃₄ represents a hydrogen atom. Represents a halogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an alkoxy group, a carbamoyl group or a nitrile group. R ₃₆ represents —CONHR ₃₇ group, —COR ₃₇ group or —COOR ₃₇ group (R ₃₇ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group) X ₃ represents a substituted or unsubstituted group, An aryl group or a heterocyclic group is represented.

In the general formula (CLA), examples of the halogen atom represented by R ₃₁ and R ₃₂ include a fluorine atom, a bromine atom, and a chlorine atom, and the alkyl group is an alkyl group having up to 20 carbon atoms (methyl , Ethyl, butyl, dodecyl and the like, and the alkenyl group includes alkenyl groups having up to 20 carbon atoms (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3 -Propenyl, 3-pentenyl, 1-methyl-3-butenyl and the like, and the alkoxy group includes an alkoxy group having up to 20 carbon atoms (methoxy, ethoxy and the like). Examples of the alkyl group represented by R ₃₀ in the —NHCOR ₃₀ group include alkyl groups having up to 20 carbon atoms (methyl, ethyl, butyl, dodecyl, etc.), and aryl groups such as phenyl and naphthyl. Examples of the heterocyclic group include thienyl, furyl, imidazolyl, pyrazolyl, pyrrolyl and the like. The alkyl group represented by R ₃₃ is preferably an alkyl group having up to 20 carbon atoms, and examples thereof include methyl, ethyl, butyl, dodecyl and the like, and the aryl group is preferably an aryl group having 6 to 20 carbon atoms. Examples thereof include phenyl and naphthyl, and examples of the heterocyclic group include thienyl, furyl, imidazolyl, pyrazolyl, pyrrolyl and the like.

In the -CONHR ₃₅ group, -COR ₃₅ group or -COOR ₃₅ group represented by W ₃ , the alkyl group represented by R ₃₅ is preferably an alkyl group having up to 20 carbon atoms, such as methyl, ethyl , Butyl, dodecyl and the like, and the aryl group is preferably an aryl group having 6 to 20 carbon atoms, such as phenyl and naphthyl, and the heterocyclic group includes, for example, thienyl, furyl, imidazolyl and pyrazolyl. , Pyrrolyl and the like.

Examples of the halogen atom represented by R ₃₄ include fluorine, chlorine, bromine and iodine. Examples of the alkyl group include chain or cyclic alkyl groups such as methyl, butyl, dodecyl and cyclohexyl. Examples of the group include alkenyl groups having up to 20 carbon atoms (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3- Butenyl etc.), examples of the alkoxy group include methoxy, butoxy, tetradecyloxy and the like, and examples of the carbamoyl group include diethylcarbamoyl, phenylcarbamoyl and the like. Nitrile groups are also preferred. Among these, a hydrogen atom and an alkyl group are more preferable.

R ₃₃ and R ₃₄ may be connected to each other to form a ring structure. The above groups can further have a single substituent or multiple substituents. Typical substituents include halogen atoms (fluorine, chlorine, bromine, etc.), alkyl groups (methyl, ethyl, propyl, butyl, dodecyl, etc.), hydroxyl groups, cyano groups, nitro groups, alkoxy groups (methoxy, ethoxy, etc.) ), Alkylsulfonamide groups (such as methylsulfonamide, octylsulfonamide), arylsulfonamides (such as phenylsulfonamide, naphthylsulfonamide groups), alkylsulfamoyl groups (such as butylsulfamoyl), arylsulfamoyl ( Phenylsulfamoyl etc.), alkyloxycarbonyl group (methoxycarbonyl etc.), aryloxycarbonyl group (phenyloxycarbonyl etc.), aminosulfonamide group, acylamino group, carbamoyl group, sulfonyl group, sulfinyl group, sulfoxy group, E group, an aryloxy group, an alkoxy group, an alkylcarbonyl group, arylcarbonyl group, and an amino carbonyl group.

R ₃₀ or R ₃₅ is preferably a phenyl group, more preferably a phenyl group having a plurality of halogen atoms and cyano groups as substituents.

In the —CONHR ₃₇ group, —COR ₃₇ group or —COOR ₃₇ group represented by R ₃₆ , the alkyl group represented by R ₃₇ is preferably an alkyl group having up to 20 carbon atoms, for example, methyl, ethyl, butyl The aryl group is preferably an aryl group having 6 to 20 carbon atoms, such as phenyl and naphthyl. Examples of the heterocyclic group include thienyl, furyl, imidazolyl, pyrazolyl, pyrrolyl and the like. Is mentioned.

As the substituent that the group represented by R ₃₇ can have, the same substituents as those described in the description of R _{31 to} R _{34 in} formula (CLA) can be used.

Examples of the aryl group represented by X ₃ include aryl groups having 6 to 20 carbon atoms such as phenyl and naphthyl. Examples of the heterocyclic group include thienyl, furyl, imidazolyl, pyrazolyl, pyrrolyl and the like. . Examples of the substituent that the group represented by X ₃ can have include the same substituents as those described in the description of R _{31 to} R _{34 in} formula (CLA). The group represented by X ₃ is preferably an aryl group or heterocyclic group having an alkylamino group (such as diethylamino) at the para position.

  These groups may include photographically useful groups.

  Specific examples of the cyan color forming leuco dye (CLA) are shown below, but the cyan color forming leuco dye used in the present invention is not limited thereto.

  Next, the compound represented by formula (CLB-I) will be described. The compound represented by the general formula (CLB-I) is preferably a compound represented by the following general formula (CLB-II) or (CLB-III), and most preferably a compound represented by (CLB-III). .

  First, the compound represented by formula (CLB-I) will be described.

In the formula, R ₄₁ , R ₄₂ , R _40a and R _40b each represent a hydrogen atom, an aliphatic group, an aromatic group, an alkoxy group, an aryloxy group, an acylamino group, a sulfonamide group, a carbamoyl group, or a halogen atom. R ₄₃ represents a hydrogen atom, an aliphatic group, an aromatic group, an acyl group, an alkoxycarbonyl group, an aryloxycarboquinyl group, a carbamoyl group, a sulfamoyl group, or a sulfonyl group. X ₄₁ and X ₄₂ represent a substitutable group on the benzene ring. m ₄₁ and m ₄₂ represents an integer of 0 to 5. When m ₄₁ and m ₄₂ are 2 or more, the plurality of X ₄₁ and X ₄₂ may be the same or different.

Specific examples of the aliphatic group represented by R ₄₁ , R ₄₂ , R _40a and R _40b include hydrocarbon groups such as an alkyl group, an alkenyl group and an alkynyl group. These hydrocarbon groups preferably have 1 to 25 carbon atoms, and more preferably 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 25 carbon atoms include methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl, and cyclohexyl, cycloalkyl groups such as cyclohexyl and cyclopentyl groups, and alkenyl groups such as ethenyl-2. Examples of alkynyl groups include ethynyl, 1-propynyl, propargyl and the like, such as -propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl and the like.

Specific examples of the aromatic group represented by R ₄₁ , R ₄₂ , R _40a and R _40b include aryl groups (phenyl, naphthyl, etc.), heterocyclic groups (pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl). , Pyrimidinyl, pyridazinyl, selenazolyl, sriphoranyl, piperidinyl, pyrazolyl, tetrazolyl and the like.

  Specific examples of the alkoxy group include methoxy, ethoxy, i-propoxy group, t-butoxy and the like, specific examples of the aryloxy group include phenoxy, naphthyloxy and the like, and the acylamino group includes acetylamino, benzoylamino and the like. However, specific examples of the sulfonamide group include methanesulfonamide, butanesulfonamide, octanesulfonamide, and benzenesulfonamide, and examples of the carbamoyl group include aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, and pentyl. Examples include aminocarbonyl, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl and the like.

  The halogen atom is chlorine, bromine or iodine.

R ₄₁ and R ₄₂ are preferably an aliphatic group, an alkoxy group, an aryloxy group, more preferably an alkyl group or an alkoxy group, still more preferably a secondary or tertiary alkyl group or an alkoxy group.

R _40a and R _40b are preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom.

Examples of the aliphatic group, aromatic group, alkoxy group and aryloxy group represented by R ₄₃ include the same groups as the specific examples for R ₄₁ and R ₄₂ .

Specific examples of the acyl group represented by R ₄₃ include acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl and the like.

Specific examples of the alkoxycarbonyl group represented by R ₄₃ include a methoxycarbonyl group, an ethoxycarbonyl group, a t-butoxycarbonyl group, and the like.

Specific examples of the aryloxycarbonyl group represented by R ₄₃ include phenoxycarbonyl and the like. Examples of the carbamoyl group include aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl, cyclohexylaminocarbonyl. , Phenylaminocarbonyl, 2-pyridylaminocarbonyl and the like, examples of the sulfamoyl group include methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl and the like, and examples of the sulfonyl group include methylsulfonyl, butylsulfonyl and octyl. And sulfonyl.

R ₄₃ is preferably a hydrogen atom, an alkyl group, or an acyl group, more preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group.

Specific examples of the group that can be substituted on the benzene ring represented by X ₄₁ and X ₄₂ include alkyl groups having 1 to 25 carbon atoms (methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl). Cyclohexyl, etc.), cycloalkyl groups (cyclohexyl, cyclopentyl, etc.), alkenyl groups (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1 -Methyl-3-butenyl etc.), alkynyl groups (ethynyl, propargyl etc.), glycidyl groups, acrylate groups, methacrylate groups, aryl groups (phenyl, naphthyl etc.), heterocyclic groups (pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, Pyrrolyl, pyrazinyl, pyrimidinyl, pyridazinyl, Lenazolyl, sulforanyl, piperidinyl, pyrazolyl, tetrazolyl etc.), halogen atom (chlorine, bromine, iodine, fluorine etc.), alkoxy group (methoxy, ethoxy, propyloxy, pentyloxy, cyclopentyloxy, hexyloxy, cyclohexyloxy etc.), aryl Oxy group (phenoxy, etc.), alkoxycarbonyl group (methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl, etc.), aryloxycarbonyl group (phenyloxycarbonyl, etc.), sulfonamide group (methanesulfonamide, ethanesulfonamide, butanesulfone) Amide, hexanesulfonamide, cyclohexanesulfonamide, benzenesulfonamide, etc.), sulfamoyl group (aminosulfonyl, methylaminosulfonyl, di-) Tilaminosulfonyl, butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pyridylaminosulfonyl, etc.), ureido groups (methylureido, ethylureido, pentylureido, cyclohexylureido, phenylureido, 2-pyridylureido, etc.) ), Acyl groups (acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl, etc.), carbamoyl groups (aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl, cyclohexylaminocarbonyl, phenyl) Aminocarbonyl, 2-pyridylaminocarbonyl, etc.), amide groups (acetamide, propion) Amide, butanamide, hexaneamide, benzamide, etc.), sulfonyl group (methylsulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexylsulfonyl, phenylsulfonyl, 2-pyridylsulfonyl, etc.), sulfonamide group (methylsulfonamide, octylsulfonamide, phenylsulfone) Amide, naphthylsulfonamide, etc.), amino group (amino, ethylamino, dimethylamino, butylamino, cyclopentylamino, anilino, 2-pyridylamino, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group Etc. Further, these groups may be further substituted with these groups.

X ₄₁ and X ₄₂ are preferably an alkoxy group, an aryloxy group, a carbamoyl group, an amide group, a sulfonamide group, an amino group, more preferably an alkoxy group or an amino group.

  Next, among the compounds represented by the general formula (CLB-I), the compounds represented by the general formula (CLB-II) and the general formula (CLB-III) which are preferably used will be described.

Wherein, R _41, R _42, R ₄₃ are each synonymous with R _41, R _42, R ₄₃ in the general formula (CLB-I). X ₄₃ and X ₄₄ each represents an aliphatic group, an aromatic group, an amino group, an alkoxy group or an aryloxy group.

Examples of the aliphatic group, aromatic group, amino group, alkoxy group and aryloxy group represented by X ₄₃ and X ₄₄ are the aliphatic groups represented by X ₄₁ and X ₄₂ in the general formula (CLB-I). Examples thereof include the same groups as the specific examples of the group, aromatic group, amino group, alkoxy group and aryloxy group. X ₄₃ and X ₄₄ are preferably an alkoxy group, an aryloxy group or an amino group, more preferably an alkoxy group or an amino group.

R ₄₄ , R ₄₅ , R ₄₆ and R ₄₇ each represent a hydrogen atom or an alkyl group. Specific examples of the alkyl group include methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl and the like. These groups may have a substituent at an arbitrary position, and examples of the substituent include the groups exemplified as the substituent in the general formula (CLB-I). R ₄₄ , R ₄₅ , R ₄₆ and R ₄₇ are preferably an alkyl group having 1 to 10 carbon atoms, more preferably methyl or ethyl.

  The compounds represented by the general formulas (CLB-I) to (CLB-III) can be easily synthesized by a conventionally known method such as the method described in JP-B-7-45477. Specific examples of the leuco dyes represented by the general formulas (CLB-I) to (CLB-III) are shown below, but the present invention is not limited thereto.

  The addition amount of the cyan chromophoric leuco dye is usually 0.00001 to 0.05 mol, preferably 0.0005 to 0.02 mol, more preferably 0.001 to 0.01 mol, per mol of silver. is there. The addition ratio of the cyan color-forming leuco dye to the sum of the reducing agents is preferably 0.001 to 0.2, more preferably 0.005 to 0.1 in terms of molar ratio.

  In the silver salt photothermographic dry imaging material of the present invention, the sum of the maximum densities at the maximum absorption wavelength of a dye image formed with a cyan leuco dye is preferably 0.01 to 0.50, more preferably 0.02 to 0.02. It is preferable to develop the color so as to have 0.30, particularly preferably 0.03 to 0.10.

  In the present invention, in addition to the above-described cyan color-forming leuco dye, a magenta color-forming leuco dye or a yellow color-forming leuco dye can be used in combination to enable further fine color tone adjustment.

  As a method for adding the yellow color-forming leuco dyes represented by the general formulas (YA) and (YB) and the cyan color-forming leuco dyes represented by the general formulas (CLA) and (CLB-I) to (CLB-III) The reducing agent represented by the general formula (1) can be added by the same method as that of the reducing agent, and can be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, a solid fine particle dispersion form, You may make it contain in a photosensitive material.

  Reducing agent of general formula (1), yellow chromophoric leuco dye of general formula (YA), (YB) and cyan chromophoric leuco dye of general formula (CLA), general formula (CLB-I) to (CLB-III) Is preferably contained in the photosensitive layer containing the aliphatic carboxylic acid silver salt, but one may be contained in the photosensitive layer and the other may be contained in the non-photosensitive layer adjacent to the photosensitive layer. May be contained in the non-photosensitive layer. When the photosensitive layer is composed of a plurality of layers, they may be contained in separate layers.

[Anti-fogging agent, image stabilizer]
In any of the constituent layers of the silver salt photothermographic dry imaging material of the present invention, an antifoggant for preventing fogging during storage before thermal development, and for preventing image deterioration after thermal development It is preferable to contain an image stabilizer. The fog prevention and image stabilizer that can be used in the present invention will be described below.

  Since reducing agents with protons such as bisphenols and sulfonamidophenols are mainly used as reducing agents, these hydrogens are stabilized, the reducing agents are deactivated, and reactions that reduce silver ions are prevented. It is preferable that the compound which can be contained is contained. Further, it is preferable that a compound capable of oxidizing and bleaching silver atoms or metallic silver (silver clusters) generated during storage of raw films and images is preferably contained. Specific examples of the compound having these functions include, for example, biimidazolyl compounds, iodonium compounds and compounds capable of releasing halogen atoms as active species described in paragraphs “0096” to “0128” of JP-A-2003-270755. Can be mentioned.

  Further, a polymer having at least one repeating unit of a monomer having a halogen radical releasing group as disclosed in JP-A No. 2003-91054, vinyl sulfones described in paragraph “0013” of JP-A No. 6-208192 and / or Examples of preferred anti-fogging and image stabilizers include β-halosulfones and vinyl type inhibitors having an electron-withdrawing group described in Japanese Patent Application No. 2004-234206.

  When the reducing agent used in the present invention has an aromatic hydroxyl group (—OH), particularly in the case of bisphenols, a non-reducing compound having a group capable of forming a hydrogen bond with these groups It is preferable to use together. Specific examples of particularly preferred hydrogen bonding compounds in the present invention include compounds (II-1) to (II-40) described in paragraphs “0061” to “0064” of JP-A-2002-90937. It is done.

  On the other hand, many compounds that can release halogen atoms as active species are known as antifogging and image stabilizers. Specific examples of the compound that generates these active halogen atoms include compounds represented by general formula (9) described in paragraphs “0264” to “0271” of JP-A No. 2002-287299.

  The addition amount of these compounds is preferably within a range in which the increase in printout silver due to the formation of silver halide due to the reaction between the halogen atoms released from the compound and silver ions is not a problem. Specific examples of compounds that generate these active halogen atoms include, in addition to the above-mentioned patents, compounds (III-1) to (III-) described in paragraphs “0086” to “0087” of JP-A No. 2002-169249. 23), compounds 1-1a to 1-1o and 1-2a to 1-2o described in paragraphs “0031” to “0034” of JP-A-2003-50441, and compounds 2a to 1-20056 described in paragraphs “0050” to “0056” 2z, 2aa to 2ll, 2-1a to 2-1f, compounds 4-1 to 4-32 described in paragraphs “0055” to “0058” of JP-A No. 2003-91054, and paragraphs “0069” to “0072” Examples thereof include compounds 5-1 to 5-10.

  Antifoggants preferably used in the present invention include, for example, compound examples a to j described in paragraph “0012” of JP-A-8-314059, and thiosulfonates described in paragraph “0028” of JP-A-7-209797. Esters A to K, compound examples (1) to (44) described from page 14 of JP-A No. 55-140833, and compounds (I-1) to (I) described in paragraph “0063” of JP-A No. 2001-13627 -6), (C-1) to (C-3) described in paragraph “0066”, compounds (III-1) to (III-108) described in paragraph “0027” of JP-A-2002-90937, vinyl sulfone And / or β-halosulfones as compounds VS-1 to VS-7, compounds HS-1 to HS-5 and sulfonylbenzotriazo described in paragraph “0013” of JP-A-6-208192 Compounds KS-1 to KS-8 described in JP-A No. 2000-330235 as substituted compounds, PR-01 to PR-08 described in JP-T 2000-515995 as substituted propene nitrile compounds, JP-A 2002-2002 Examples thereof include compounds (1) -1 to (1) -132 described in paragraphs “0042” to “0051” of No. 207273.

  The antifoggant is generally used in an amount of at least 0.001 mol per 1 mol of silver. Usually, the range is 0.01 to 5 mol, preferably 0.02 to 0.6 mol, per mol of silver.

  In addition to the above compounds, the silver salt photothermographic dry imaging material may contain various compounds conventionally known as antifoggants, but produces reactive species similar to the above compounds. Even a compound that can be used may be a compound having a different antifogging mechanism. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. Nos. 3,874,946, 4,756,999. And compounds described in JP-A-9-288328 and JP-A-9-90550. Further, other antifoggants include compounds disclosed in US Pat. No. 5,028,523 and European Patents 600,587, 605,981, and 631,176.

[Toning agent]
The silver salt photothermographic dry imaging material forms a photographic image by heat development, and a toning agent (toner) that adjusts the color tone of silver as needed is usually dispersed in an (organic) binder matrix. It is preferable to contain in the state.

  Examples of suitable toning agents used in the present invention include 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 (succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide, etc.); mercaptans (3-mercapto-1,2,4-triazole, etc.); phthalazinone derivatives or metal salts of these derivatives (phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); phthalazine and phthalic acids (eg, 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 derivative and anhydride (phthalic acid) 4-methylphthalic acid, 4-nitrophthalic acid and tetrachloro Combination of at least one compound selected from the barrel anhydride, etc.). Particularly preferred toning agents are combinations of phthalazinone or phthalazine with phthalic acids and phthalic anhydrides.

[Dye / Pigment]
In silver salt photothermographic dry imaging materials, a filter layer is formed on the same side as or opposite to the photosensitive layer in order to control the amount or wavelength distribution of light transmitted through the photosensitive layer, or a dye or It is preferable to contain a pigment. As the dye used, known compounds that absorb light in various wavelength regions can be used depending on the color sensitivity of the photosensitive material. For example, when a silver salt photothermographic dry imaging material is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (in this specification, 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. preferable. The compound having a squarylium nucleus is a compound having 1-cyclobuten-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, 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.

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

General formula (SF) (R _f − (L) _n −) _p − (Y) _m − (A) _q
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), examples of the substituent containing a fluorine atom represented by R _f include a fluorinated alkyl group having 1 to 25 carbon atoms (trifluoromethyl, trifluoroethyl, perfluoroethyl, perfluorobutyl, perfluorocarbon, Fluorooctyl, perfluorododecyl, perfluorooctadecyl, etc.) or alkenyl fluoride groups (perfluoropropenyl, perfluorobutenyl, perfluorononenyl, perfluorododecenyl, 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.

  Examples of the divalent linking group having no fluorine atom represented by L include an alkylene group (methylene, ethylene, butylene, etc.), an alkyleneoxy group (methyleneoxy, ethyleneoxy, butyleneoxy, etc.), an oxyalkylene group (oxymethylene). Oxyethylene, oxybutylene, etc.), oxyalkyleneoxy groups (oxymethyleneoxy, oxyethyleneoxy, oxyethyleneoxyethyleneoxy, etc.), phenylene groups, oxyphenylene groups, phenyloxy groups, oxyphenyloxy groups or these groups Examples include a combined group.

  A represents an anionic group or a salt thereof. For example, a carboxyl group or a salt thereof (sodium salt, potassium salt and lithium salt), a sulfo group or a salt thereof (sodium salt, potassium salt and lithium salt), a sulfuric acid half ester group or a salt thereof Examples thereof include salts (sodium salt, potassium salt and lithium salt), and phosphoric acid groups or salts thereof (sodium salt, potassium salt and the like).

  As the (p + q) -valent linking group having no fluorine atom represented by Y, for example, as a trivalent or tetravalent linking group having no fluorine atom, an atomic group composed mainly of a nitrogen atom or a carbon atom is used. Can be mentioned. n represents an integer of 0 or 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 (trifluoromethyl, pentafluoroethyl, perfluorobutyl, perfluorooctyl, perfluorooctadecyl, etc. Compound) and alkenyl compounds (compounds having perfluorohexenyl, perfluorononenyl, etc.), 3 to 6 valent alkanol compounds each having no fluorine atom introduced, and aromatic compounds having 3 to 4 hydroxyl groups Alternatively, it is obtained by introducing an anionic group (A) into the compound (partially R _f (fluorinated) alkanol compound) obtained by addition reaction or condensation reaction with a hetero compound, for example, by sulfate esterification or the like. .

  Examples of the 3 to 6-valent alkanol compound include glycerin, pentaerythritol, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentene, 1,2,6- Hexanetriol, 1,1,1-tris (hydroxymethyl) propane, 2,2-bis (butanol) -3, aliphatic triol, tetramethylolmethane, D-sorbitol, xylitol, D-mannitol and the like can be mentioned. Examples of the aromatic compound and hetero compound having 3 to 4 hydroxyl groups include 1,3,5-trihydroxybenzene (phloroglucin) and 2,4,6-trihydroxypyridine.

  Below, the preferable specific compound of the fluorine-type surfactant represented by general formula (SF) is shown.

  As a method of adding the fluorine-based surfactant represented by the general formula (SF) 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 of 1 μm or less can be dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion, and added. Many techniques for fine particle dispersion are disclosed, but they can be dispersed according to these techniques. The fluorine-based surfactant represented by the general formula (SF) is preferably added to the outermost protective layer.

The amount of the fluorosurfactant represented by the general formula (SF) is preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol per 1 m ² , particularly 1 × 10 ⁻⁵ to 1 × 10 ⁻² mol. preferable. If the range is less than the former range, 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 property modifier)
The silver salt photothermographic dry imaging material is used for contact with various devices during winding, rewinding, and transporting of the photosensitive material in a manufacturing process such as coating, drying, and processing, or a photosensitive surface and a backing coat surface. Often, it is undesirably affected by contact between photosensitive materials, such as in between. For example, the surface of the photosensitive material may be scratched or slipped, or the photosensitive material may be deteriorated in the developing device.

  Therefore, in the silver salt photothermographic dry imaging material, in order to prevent the above-described surface scratches and transportability deterioration, any one of the constituent layers of the material, particularly the outermost layer on the support, It is preferable to adjust the surface physical properties of the photosensitive material by containing a lubricant, a matting agent and the like.

  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 to 30 μm, and the organic solid lubricant particles are dispersed by a polymer dispersant. It is preferable. The melting point of the lubricant particles is 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 present invention are preferably compounds that lower the surface energy. Examples thereof include particles formed by pulverizing polyethylene, polypropylene, polytetrafluoroethylene, and copolymers thereof. Examples of organic solid lubricant particles made of polyethylene and polypropylene include polytetrafluoroethylene, polypropylene / polyethylene copolymer, polyethylene (low density), polyethylene (high density), and polypropylene.

  The organic solid lubricant particles are preferably a compound represented by the following general formula (SC1) or general formula (SC2).

Formula (SC1) (R _SC1 ) _{pX SC1} -L ₆ -X _SC2- (R _SC2 ) _q
Formula (SC2) (R _SC1 -COO-) _Z ^-- M ^{Z +}
In the formula, R _SC1 and R _SC2 are each a substituted or unsubstituted alkyl group, alkenyl group, aralkyl group or aryl group having 6 to 60 carbon atoms, and when p or q is 2 or more, a plurality of R _SC1 And R _SC2 may be the same as or different from each other. X _SC1 and X _SC2 each represent a divalent linking group containing a nitrogen atom. L ₆ represents a substituted or unsubstituted p + q valent alkyl group, alkenyl group, aralkyl group or aryl group. M represents a Z-valent metal ion.

In the compound represented by the general formula (SC1) or (SC2), the total number of carbon atoms is not particularly limited, but is generally preferably 20 or more, and more preferably 30 or more. Examples of the substituent that the alkyl group, alkenyl group, aralkyl group or aryl group in the definition of R _SC1 and R _SC2 may have include a halogen atom, a hydroxyl group, a cyano group, an alkoxy group, an aryloxy group, an alkylthio group. Groups, arylthio groups, alkoxycarbonyl groups, aryloxycarbonyl groups, amino groups, acylamino groups, sulfonylamino groups, ureido groups, carbamoyl groups, sulfamoyl groups, acyl groups, sulfonyl groups, sulfinyl groups, aryl groups and alkyl groups. be able to. These groups may further have a substituent, and preferred substituents are a halogen atom, a hydroxyl group, an alkoxy group, an alkylthio group, an alkoxycarbonyl group, an acylamino group, a sulfonylamino group, an acyl group, and an alkyl group. . As a halogen atom, a fluorine atom and a chlorine atom are preferable.

The alkyl component in the alkoxy group, alkylthio group, and alkoxycarbonyl group is the same as the alkyl group of R _SC2 described later. The amino group of the acylamino group and sulfonylamino group may be an N-substituted amino group, and the substituent is preferably an alkyl group. The groups bonded to the acylamino group, the carbonyl group of the acyl group, and the sulfonyl group of the sulfonylamino group are an alkyl group and an aryl group, and the above alkyl groups are preferable.

R _SC1 and R _SC2 are substituted or unsubstituted alkyl, alkenyl, aralkyl, or aryl groups having 6 to 60 carbon atoms, preferably 6 to 40 carbon atoms, more preferably 10 to 30 carbon atoms. The alkyl group, alkenyl group, and aralkyl group may be linear, branched, or cyclic, or may be a mixture thereof. Examples of preferred R _SC1 and R _SC2 include octyl, t-octyl, dodecyl, tetradecyl, hexadecyl, 2-hexyldecyl, octadecyl, C _n H _{2n -1} (n is 20 to 60), eicosyl, docosanyl, melininyl, Examples include octenyl, myristolyl, oleyl, erucyl, phenyl, naphthyl, benzyl, nonylphenyl, dipentylphenyl, cyclohexyl groups, and groups having these substituents.

The divalent linking groups X _SC1 and X _SC2 containing a nitrogen atom are preferably —CON (R ₃ ) —, —N (R ₄ ) CON (R ₅ ) —, and —N (R ₆ ) COO—. Here, R < ₃ > -R < ₆ > shows a hydrogen atom or a substituent, respectively.

L ₆ represents a substituted or unsubstituted p + q valent alkyl group, alkenyl group, aralkyl group or aryl group. Although carbon number of these hydrocarbon groups is not specifically limited, Preferably it is 1-60, More preferably, it is 1-40, More preferably, it is 10-40. The “p + q valence” in the p + q valent hydrocarbon group means that p + q hydrogen atoms in the hydrocarbon are removed, and p X _SC1 groups and q X _SC2 groups are bonded thereto. p and q represent an integer of 0 to 6, 1 ≦ p + q ≦ 6, and preferably 1 ≦ p + q ≦ 4. Moreover, the case where both p and q are 1 is preferable.

  The compound represented by the general formula (SC1) may be a synthetic product or a natural product. Even if it is a natural product or a synthetic product, a synthetic compound using a higher fatty acid or alcohol as a raw material includes those having different numbers of carbon atoms and those having a straight chain and a branched chain. There is no problem using it. From the viewpoint of the quality stability of the composition, a synthetic product is preferable.

  Although the specific example of a compound represented with preferable general formula (SC1) or general formula (SC2) below is shown, this invention is not limited to these.

  Lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxy stearic acid amide, oleic acid amide, erucic acid amide, ricinoleic acid amide, N-lauryl lauric acid amide, N-palmityl palmitic acid amide, N- Stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, N-stearyl-hydroxystearic acid amide, N Oleyl-hydroxystearic acid amide, methylol stearic acid amide, methylol behenic acid amide, methylene bis stearic acid amide, methylene bis lauric acid amide, methylene bis hydroxy stearic acid amide, ethyl Biscaprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene Bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, butylene bishydroxystearic acid amide, N, N'-distearyl adipic acid amide, N, N'-distearyl sebacic acid amide, methylene bisoleic acid amide, ethylenebis Oleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide, -Xylylene stearamide, N, N'-distearylisophthalamide, ethanolamine distearate, N-butyl-N'-stearyl urea, N-phenyl-N'-stearyl urea, N-stearyl-N ' -Stearyl urea, xylylene bisstearyl urea, toluylene bisstearyl urea, hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea.

  The organic solid lubricant is preferably used in a state of being dispersed in the coating solution in advance. As the name suggests, the organic solid lubricant has a property that the surface is slippery, and therefore, the affinity between water and the organic solvent is not sufficiently high in many cases. It may cause sedimentation. Aggregation or sedimentation in the coating solution is undesirable because it causes coating failure when processed into a film. Examples of a method for improving the stability of the dispersion include a method of modifying the surface and using an electrostatic effect, and a method of using a steric hindrance effect using a surface adsorbing layer by a polymer dispersant. The former is a general dispersion stabilization method, but there is a concern about the influence on the other performance of the surface modifier itself because it is used for silver salt photothermographic dry imaging materials. In either case, the latter method is preferable because the effect is easily exhibited.

  As the polymer dispersant, a binder used in the photosensitive material can be used. Specifically, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, cellulose acetate butyrate, cellulose acetate propionate, and the like can be used.

  The amount of the polymer dispersant is preferably used in the range of 1 to 200% by mass with respect to the organic solid lubricant particles as a dispersion. The dispersion method is not particularly limited, but a dissolver type, an ultrasonic type, a pressure type, or the like can be used, and it is preferable to carry out a dispersion treatment with a dispersion device having a cooling device so as not to generate heat.

  The average particle diameter of the organic solid lubricant particles refers to the average particle diameter after dispersion by the following method. In order to obtain the average particle size referred to in the present invention, a dispersion liquid containing lubricant particles is diluted, dropped onto a grid with a carbon support film and dried, and a transmission electron microscope (manufactured by JEOL Ltd .: 2000FX type) is used. Etc.), directly after taking a picture at a magnification of 5000 times, a negative is captured as a digital image by a scanner, and each particle size (equivalent circle diameter) is measured by 300 or more using an appropriate image processing software. The average particle diameter can be obtained from the arithmetic average.

  In the light-sensitive material of the present invention, at least one layer on the support contains the compound represented by the general formula (SC1) and / or the general formula (SC2), and a nonionic fluorine-containing surfactant and an anion. It is preferable to contain a fluorinated surfactant.

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

Formula (AIF) R _f1- (AO) _n -R _f2
In the formula, R _f1 and R _f2 represent a fluorine-containing aliphatic group, and may be the same or different. AO represents a divalent group having at least one alkyleneoxy group, and n represents an integer of 1 to 30.

Examples of the fluorine-containing aliphatic group represented by R _f1 and R _f2 include aliphatic groups composed of linear, branched and cyclic groups, or combinations thereof, such as alkylcycloaliphatic groups. Preferred fluorine-containing aliphatic group, each fluoroalkyl group having 1 to 20 carbon atoms _{(-C 4 F 9, -C 8} F 17 , etc.), a sulfo fluoroalkyl group _{(C 7 F 15 SO 3 -} , C 8 F ₁₇ SO ₃ — etc.), C _n F _2n + ₁ SO ₂ N (R ₁ ) R ₂ — group (R ₁ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkyl carboxyl group or an aryl group, respectively. , R ₂ represents an alkylene group having 1 to 20 carbon atoms and an alkylenecarbonyl group, and n represents an integer of 1 to 20. C ₇ F ₁₅ SO ₂ N (C ₂ H ₅ ) CH ₂ —, C ₈ F ₁₇ SO ₂ N (CH ₂ COOH) CH ₂ CH ₂ CH ₂ — and the like), which may further have a substituent.

  AO is a group having an alkyleneoxy group such as ethyleneoxy, propyleneoxy, i-propyleneoxy, and may have a substituent such as an amino group at the terminal. n is preferably an integer of 5 to 15.

  Specific examples of the nonionic fluorine-containing surfactant represented by the general formula (AIF) are shown below, but the present invention is not limited thereto.

  Moreover, there is no restriction | limiting in particular as an anionic fluorine-containing surfactant (FA) which can be used by this invention, Although a specific compound is shown below, this invention is not limited to these.

The amount of each fluorine-containing surfactant used is generally from 0.01 to 1 g, preferably from 10 to 500 mg, per 1 m ² of the photosensitive material. More preferably, it is 50-300 mg.

  In addition to the above, the fluorine-containing surfactants include ionic fluorine-based surfactants described in JP-A-60-244945, JP-A-63-306437, and JP-A-1-24245; Fluorosurfactants used in combination with anions and cations described in 197068 and 5-204115 can be used.

  The addition layer of the fluorine-containing surfactant is not particularly limited and may be in any layer, but is preferably contained in the outermost surface layer.

[Support]
Examples of the support material used for the silver salt photothermographic dry imaging material include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (aluminum, etc.), etc. A material that can be processed into a flexible sheet or roll is preferred. Therefore, as a support in the silver salt 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 ( A plastic film such as a TAC) or 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 coat 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.

Especially, in this invention, it is preferable to contain a conductive metal oxide in the surface protective layer by the side of a backing quark layer. 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 grain 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 respect ZnO, Sb for SnO _2, Nb, P, the addition of such a halogen element, and Nb for TiO _2, Ta etc. Is 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 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, and 58-62647. 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 usable particle size 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 length / diameter ratio is 3 or more. SnO ₂ is commercially available from Ishihara Sangyo Co., Ltd., and SNS10M, SN-100P, SN-100D, FSS10M and the like can be used.

[Layer structure]
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-image forming 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 between the photosensitive materials or in a roll for conveying the photosensitive material. In order to prevent “sticking”, a backcoat layer is provided.

As a binder used in these protective layers and backcoat layers, polymers having a glass transition point (T _g ) higher than that of the photosensitive layer and less likely to be scratched or deformed, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propio. A polymer such as nate is selected from the binders.

  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 may be formed by preparing a coating solution in which the above-described constituent layers are dissolved or dispersed in a solvent, applying a plurality of these coating solutions simultaneously, and then performing a heat treatment. preferable. Here, “multiple simultaneous multi-layer coating” means that a coating solution for each constituent layer (photosensitive layer, protective layer, etc.) is prepared, and when this is coated on a support, the coating and drying are repeated for each layer individually. Instead, it means that the respective constituent layers are formed in such a state that simultaneous multilayer coating and drying can be performed. 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 of each constituent layer simultaneously, for example, bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, reverse roll coating method, gravure coating method, extrusion coating. A known method such as a method can be used. Of these various methods, 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 the undercoat layer when the backcoat layer is provided. Japanese Unexamined Patent Publication No. 2000-15173 has a detailed description on the simultaneous multilayer coating method in the silver salt photothermographic dry imaging material.

The silver coating amount is preferably selected in accordance with the purpose of the light-sensitive material, but is preferably 0.8 to 1.5 g / m ² for the purpose of medical images, and 1.0 to 1 .3 g / m ² is more preferable. Among the coated silver amount, those derived from silver halide grains preferably occupy 2 to 18%, more preferably 5 to 15%, based on the total silver amount. The coating density of silver halide grains of 0.01 μm or more (equivalent particle diameter equivalent to sphere) is preferably 1 × 10 ¹⁴ to 1 × 10 ¹⁸ particles / m ² . Furthermore, 1 * 10 < ¹⁵ > -1 * 10 < ¹⁷ > piece / m < ² > is preferable.

Furthermore, the coating density of the non-photosensitive long-chain aliphatic carboxylate is 1 × 10 ⁻¹⁷ to 1 × 10 ⁻¹⁴ g per silver halide grain of 0.01 μm or more (equivalent particle diameter in terms of sphere). Is preferably 1 × 10 ⁻¹⁶ to 1 × 10 ⁻¹⁵ g.

  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.

The silver salt photothermographic dry imaging material of the present invention preferably contains a solvent in the range of 5 to 1000 mg / m ² during development. It is more preferable to adjust so that it may be 10-150 mg / m < ² >. As a result, a silver salt photothermographic dry imaging material with high sensitivity, low fog and high maximum density is obtained. Examples of the solvent include, but are not limited to, those described in paragraph “0030” of JP-A No. 2001-264930. These solvents can be used alone or in combination of several kinds. The content of the solvent in the photosensitive material can be adjusted by changing conditions such as temperature conditions in the drying step after the coating step. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

[Heat development]
The silver salt photothermographic dry imaging material of the present invention is characterized in that after imagewise exposure, the silver salt photothermographic dry imaging material is processed with a heat developing machine that forms an image by heating at a desired development temperature. The heat development temperature is preferably in the range of 110 to 150 ° C, and more preferably in the range of 115 to 135 ° C. If the heating temperature is less than 80 ° C., sufficient image density cannot be obtained in a short time, and if the heating temperature is high (particularly 200 ° C. or more), transfer to the roller due to melting of the binder, transportability, developing machine, etc. are also adversely affected. Effect. By heating, a silver image is generated by a redox reaction between the aliphatic carboxylic acid silver salt (which functions as an oxidizing agent) and the reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside.

  Any heating means may be used, such as contact heating with a heating drum or a heating plate, non-contact heating such as radiation, but contact heating with a heating plate is preferred. The contact heating surface can be either the image forming layer (photosensitive layer) side or the non-image forming layer (non-photosensitive layer) side, but the non-image forming layer (non-photosensitive layer) side is contact-heated for stability to the processing environment. A surface is preferred. The developing unit is preferably configured by combining a plurality of independently temperature-controlled zones and a plurality of means, and further has at least one heat retention zone for maintaining a specific developing temperature. preferable. Therefore, in the thermal development apparatus that can be preferably used in the present invention, the thermal development process can adopt a separate configuration for the temperature raising portion and the heat retaining portion, and the heating means such as a heating member and the sheet film are in close contact with each other in the temperature raising portion. It is possible to prevent the occurrence of density unevenness by making contact, and it is not necessary to make such close contact in the heat retaining part, and by using an optimal heating method that is different between the temperature rising part and the heat retaining part, high image quality without density unevenness Thus, it is possible to achieve a configuration that allows rapid processing of the thermal development process, downsizing of the apparatus, and cost reduction.

  In the above heat development apparatus, the temperature raising unit heats the sheet film of the silver salt photothermographic dry imaging material while pressing the sheet film against a plate heater by a counter roller, and the heat retaining unit has a heater in at least one of them. The sheet film can be heated in a slit formed between the guides. While the sheet heater is pressed against the plate heater by the opposing roller and brought into contact with the plate heater in the first zone, the plate heater and the sheet film can be brought into close contact with each other, while the temperature rise in the second zone is maintained. Since it is only necessary to carry while heating (warming) between the slits (guide gaps) with the conveying force of the opposite roller of the part, while maintaining high image quality without density unevenness, driving parts for the conveyance system become unnecessary, Further, the size of the apparatus can be reduced and the cost can be reduced without requiring much accuracy of the slit size.

  According to this heat development apparatus, in the first zone, the sheet film is heated by securing a close contact between the heating means such as a heating member and the sheet film, and the occurrence of density unevenness is suppressed. Since there is no need to make contact, by keeping the sheet film warm in the guide gap in the second zone, it is possible to quickly process the thermal development process, downsize the equipment and reduce costs while maintaining high image quality without density unevenness. Can be configured. When the guide gap is 3 mm or less, there is little effect on the heat retaining performance regardless of the sheet film conveyance posture in the second zone, and the positioning accuracy between the fixed guide and another guide is not so required, and both guides are processed. The tolerance for time curvature error and mounting accuracy is increased, resulting in a significant increase in design freedom, which can contribute to cost reduction of the apparatus.

  In the thermal development apparatus, it is preferable that a guide gap of the second zone is in a range of 1 to 3 mm. When the guide gap is 1 mm or more, the coated surface (photosensitive layer) of the silver salt photothermographic dry imaging material of the sheet film is difficult to touch the guide surface, and the occurrence of scratches is reduced. Also, if the guide gap is 3 mm or less, there is little influence on the heat retention performance regardless of the sheet film conveyance posture in the second zone, and the placement accuracy between the fixed guide and another guide is not required so much. This increases the tolerance for the curvature error and the mounting accuracy during machining, greatly increasing the degree of design freedom, and can contribute to the cost reduction of the apparatus.

  Further, it is preferable that the fixed guide and the guide in the second zone have substantially the same curvature. When the curvature of the guide in the second zone is given to reduce the size of the apparatus, a guide with a substantially constant guide gap can be configured.

  Further, the engagement time with the sheet film in the temperature raising portion and the heat retaining portion can be configured to be 10 seconds or less, and the period of the temperature raising step and the heat retaining step can be shortened so that the rapid processing of the thermal development process can be performed. Is possible.

  In addition, a concave portion is provided between the temperature raising portion and the heat retaining portion so that foreign matter from the temperature rising portion enters the concave portion, so that the front end of the film is conveyed while the temperature raising portion is conveyed. The foreign matter accumulated and moved by the portion can be prevented from being brought into the heat retaining portion, and jamming, scratches, density unevenness, etc. can be prevented from occurring on the sheet film.

  In addition, it is preferable that the said temperature rising part and the said heat retention part are comprised so that the photosensitive layer side of silver salt photothermographic dry imaging material may be open | released and the said sheet | seat film may be heated. Also in the cooling section, it is preferable to perform cooling by opening the photosensitive layer side of the silver salt photothermographic dry imaging material.

  However, the mechanism of the heat retaining zone may be a mechanism that maintains the heated film temperature, and is not limited to the above. The development time is preferably 5 to 10 seconds.

(Developer heat development apparatus having a preheat zone that is heated to 70 to 100 ° C. immediately before thermal development)
In the present invention, an image is obtained by processing a silver salt photothermographic dry imaging material with a heat developing machine apparatus having a preheat zone heated to 70 to 100 ° C. after imagewise exposure and before a heat development step of heating at a desired development temperature. Preferably formed. Furthermore, it is preferable to process with the heat developing machine apparatus which has a preheat zone heated to 90-100 degreeC. Although there is no restriction | limiting in particular in the heating mechanism of a preheat zone, From a viewpoint of cost and controllability, contact heating with a heating plate is preferable. The heating temperature accuracy of the preheat zone is preferably ± 1 ° C., more preferably ± 0.5 ° C. Although the appropriate value of the heating time varies depending on the heating mechanism, it is preferably in the range of 0.5 to 7 seconds, and more preferably in the range of 1 to 3 seconds.

(Developer heat development apparatus having a slow cooling zone in which development is stopped by adjusting to a temperature lower by 10 to 20 ° C. than the thermal development temperature)
The present invention has a slow cooling zone in which a silver salt photothermographic dry imaging material is imagewise exposed, heated at a desired development temperature, and then adjusted to a temperature lower by 10 to 20 ° C. than the thermal development temperature to stop development. It is preferable to form an image by processing with a heat developing machine. Furthermore, it is preferable to process with a heat developing machine apparatus having a slow cooling zone in which the development is stopped by adjusting the temperature to be 10 to 15 ° C. lower than the heat development temperature. The mechanism of the slow cooling zone is not particularly limited, but contact cooling with a plate adjusted to a desired temperature is preferable from the viewpoint of cost and controllability. The temperature accuracy of the slow cooling zone is preferably ± 1 ° C., more preferably ± 0.5 ° C. The slow cooling time is preferably x0.25 times or more with respect to the development time, and is preferably in the range of x0.25 to x1.0 times in view of rapid processing.

  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 silver salt photothermographic dry imaging material formed by heat development through laser recording from the film supply unit to the outside of the apparatus.

(Exposure laser image recording unit)
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. Conditions can be adopted.

  The silver salt photothermographic dry imaging material of the present invention preferably uses a laser beam when recording an image. 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.

Further, the silver salt photothermographic dry imaging material of the present invention preferably exhibits its characteristics by being exposed for a short time with light of high illuminance 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 small, and a high sensitivity system can be designed. More preferably, the light quantity is ² mW-50 W / mm < ² >, More preferably, it is 10 mW-50 W / mm < ² >. Any light source may be used as long as it is as described above, but it can be preferably achieved by using a laser.

  As a laser preferably used for the photosensitive material of the present invention, a gas laser (Ar ion, Kr ion, He—Ne), YAG laser, dye laser, semiconductor laser and the like are preferable. Also, a semiconductor laser and a second harmonic generation element can be used. Further, if the spectral sensitivity distribution of the halation dye and the photosensitive silver halide grains in the image forming layer is adjusted, even a silver salt photothermographic dry imaging material using the structure of the present invention can emit a blue to purple semiconductor laser (wavelength 350 nm). And the like having a peak intensity at ˜440 nm can be used. Examples of the blue to purple light-emitting high-power semiconductor laser include NLHV3000E semiconductor laser manufactured by Nichia Corporation.

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

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

  The beam spot diameter on the photosensitive material exposure surface when the photosensitive material is scanned with the laser beam 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.

  Further, 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 single longitudinal mode scanning laser beam, image quality degradation such as generation of interference fringe-like unevenness is reduced. In order to make a vertical multiplex, methods such as using return light by multiplexing and applying high frequency superposition are preferable. Note that the vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength 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 means of a laser printer or a digital copying machine for writing an image for each line by one scanning because of a demand for high resolution and high 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 laser printers and digital copiers is for the purpose of writing images line by line in one scan, and one line from the image formation position of one laser light. 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 with an interval of the order of several tens of μm, and the print density is 400 dpi (1 dpi = 2 dots per inch). The pitch in the sub-scanning direction 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 location on the exposure surface while changing the incident angle. In this case, the exposure energy on the exposure surface when writing with one ordinary 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 (E _n ), it is preferable that the range is 0.9 × E ≦ E _n × N ≦ 1.1 × E. 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 the occurrence of interference fringes is suppressed.

In the above description, a plurality of laser beams having the same wavelength as λ are used. However, ones having different wavelengths may be used. In this case, it is preferable that (λ−30) <λ ₁ , λ ₂ ,... Λ _n ≦ (λ + 30) with respect to λ [nm].

In the above-described image recording methods of the first, second, and third aspects, the laser used for scanning exposure is generally well-known solid laser such as ruby laser, YAG laser, glass laser; Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He—Cd laser, N ₂ laser, excimer laser and other gas lasers; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP Semiconductor lasers such as ₂ lasers and GaSb lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner according to the application, but among these, semiconductors with a wavelength of 600 to 1200 nm due to maintenance and light source size problems laser Preferably used by laser light. In the laser used in a laser imager or a laser image setter, the beam spot diameter on the exposed surface of the material when scanned with a silver salt photothermographic dry imaging material is generally 5 to 75 μm as a short axis diameter, and is long. The axial diameter is in the range of 5 to 100 μm, and the laser beam scanning speed is set to an optimum value for each silver salt photothermographic dry imaging material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the silver salt photothermographic dry imaging material. be able to.

(Development heat development unit)
In the present invention, from the viewpoint of speeding up, it is necessary to correspond to an embodiment in which exposure processing and heat development processing are performed simultaneously. In order to perform the exposure process and the thermal development process at the same time, that is, in order to start development on a part of the sheet film that has already been exposed while exposing a part of the sheet photosensitive material film, It is preferable that the distance between the heat developing portions is 0 to 50 cm, and thereby, a series of processing time for exposure and development becomes extremely short. The preferable range of this distance is 3 to 40 cm, more preferably 5 to 30 cm. Here, the exposure part refers to the position where the light from the exposure light source is irradiated to the silver salt photothermographic dry imaging material, and the thermal development part refers to the first heating for the silver salt photothermographic dry imaging material to perform thermal development. Say the position to be.

  In addition, the conveyance speed in the heat development part of a photosensitive material sheet film 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.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. Unless otherwise specified, “part” in the examples represents “part by mass” and “%” represents “mass%”.

<Preparation of underdrawn support>
Corona discharge treatment is performed on both sides of a biaxially stretched PET film having a blue dye concentration of 0.113 under conditions of 10 W / m ² min. After coating to a thickness of 0.06 μm and drying at 140 ° C., and subsequently coating a backcoat surface side undercoat upper layer coating solution having the following composition to a dry film thickness of 0.2 μm, the temperature is 140 ° C. Dried. On the other side, a photosensitive layer side undercoat coating solution having the following composition is applied to a dry film thickness of 0.25 μm, dried at 140 ° C., and then a photosensitive layer having the following composition. The side subbing upper layer coating solution was applied to a dry film thickness of 0.06 μm and then dried at 140 ° C. These were heat-treated at 140 ° C. for 2 minutes to obtain an underdrawn support.

(Backcoat surface side undercoat lower layer coating solution)
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
Tin oxide sol (solid content 10%, synthesized by the method described in JP-A-10-059720)
91.0g
Surfactant for undercoat layer 0.5g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

Surfactant for undercoat layer: 2,4- (C ₉ H ₁₉ ) ₂ —C ₆ H ₃ — (CH ₂ CH ₂ O) ₁₂ SO ₃ Na
(Backcoat surface side undercoat upper layer coating solution)
Modified aqueous polyester for back coat layer (solid content 18%) 215.0g below
0.4 g of surfactant for undercoat layer
Spherical silica matting agent (Seahoster KE-P50: manufactured by Nippon Shokubai Co., Ltd.) 0.3 g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

Surfactant for undercoat layer: 2,4- (C ₉ H ₁₉ ) ₂ —C ₆ H ₃ — (CH ₂ CH ₂ O) ₁₂ SO ₃ Na
<Synthesis of modified aqueous polyester for back coat layer>
In a polymerization reactor, 35.4 parts of dimethyl terephthalate, 33.63 parts of dimethyl isophthalate, 17.92 parts of 5-sulfo-isophthalic acid dimethyl sodium salt, 62 parts of ethylene glycol, 0.065 parts of calcium acetate monohydrate Then, 0.022 part of manganese acetate tetrahydrate was added and the ester exchange reaction was carried out while distilling methanol at 170-220 ° C. in a nitrogen stream. Then, 0.04 part of trimethyl phosphate was added as a polycondensation catalyst. 0.04 part of antimony oxide and 6.8 parts of 1,4-cyclohexanedicarboxylic acid were added, and an approximately theoretical amount of water was distilled off at a reaction temperature of 220 to 235 ° C. for esterification. Thereafter, 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 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. The mixture was stirred at room temperature for 30 minutes, 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%.

  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, and filtered, and prepared the solution of the modified | denatured aqueous | water-based polyester for back layers with a solid content concentration of 18%.

(Coating solution for photosensitive layer side undercoat)
Copolymer latex of styrene / acetoacetoxyethyl methacrylate / glycidyl methacrylate / butyl acrylate (40/40/20 / 0.5) (solid content 30%) 70.0 g
Surfactant for undercoat layer 0.3g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

Surfactant for undercoat layer: 2,4- (C ₉ H ₁₉ ) ₂ —C ₆ H ₃ — (CH ₂ CH ₂ O) ₁₂ SO ₃ Na
(Photosensitive layer side undercoat upper layer coating solution)
Modified aqueous polyester for photosensitive layer * (solid content 18%) 80.0 g below
0.4 g of surfactant for undercoat layer
Spherical silica matting agent (Seahoster KE-P50: manufactured by Nippon Shokubai Co., Ltd.) 0.3 g
Distilled water was added to make 1000 ml, and a coating solution having a solid content concentration of 0.5% was obtained.

Surfactant for undercoat layer: 2,4- (C ₉ H ₁₉ ) ₂ —C ₆ H ₃ — (CH ₂ CH ₂ O) ₁₂ SO ₃ Na
<Synthesis of modified aqueous polyester for photosensitive layer>
Similar to the modified aqueous polyester for backcoat layer except that the precursor solution of the modified aqueous polyester 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 butyl acrylate. Thus, a solution of a modified aqueous polyester for a photosensitive layer having a solid content concentration of 18% was prepared.

<Preparation of silver halide grain-containing and aliphatic carboxylic acid silver salt emulsion for photosensitive layer>
(Solution A)
Phthalated gelatin (phthalated modification rate 99%) 66.20g
Surfactant AO-1 (10% methanol aqueous solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water.

_{AO-1: 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)
(Solution B)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(Solution C)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finish to 660 ml with water.
(Solution D)
154.90 g of potassium bromide
4.41 g of potassium iodide
15 ml of iron (II) hexacyanide (0.5% solution)
0.93 ml potassium hexachloroiridate (III) (1% solution)
Finish to 1982 ml with water.
(Solution E)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount (solution F)
Potassium hydroxide 0.71g
Finish to 20 ml with water.
(Solution G)
56% aqueous acetic acid solution 10.0ml
(Solution H)
Anhydrous sodium carbonate 1.16g
Finish to 107 ml with water.

  Using a mixing stirrer shown in Japanese Patent Publication No. 58-58288, while controlling 1/4 of solution B in solution A and the total amount of solution C to 35 ° C. and pAg of 8.09, 4 minutes 45 Nucleation was performed by adding in seconds. After 1 minute, the entire amount of Solution F was added. During this time, the solution E was used appropriately for the adjustment of pAg. After the elapse of 6 minutes, 3/4 amount of the solution B and the whole amount of the solution D were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling the temperature at 35 ° C. and pAg 8.09. After stirring for 5 minutes, the temperature was lowered to 30 ° C., the entire amount of Solution G was added, and silver halide grains were allowed to settle. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, silver halide grains were sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, silver halide emulsion grains were precipitated. After leaving 1500 ml of the sedimented portion and removing the supernatant, solution H was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 100 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 a photosensitive silver halide grain emulsion.

  The emulsion grains were monodisperse cubic silver iodobromide grains having an average grain size of 0.043 μm and a [100] face ratio of 92%.

<Preparation of copolymer>
A 0.5 L four-necked separable flask is equipped with a dropping device, a thermometer, a nitrogen gas introduction tube, a stirring device, and a reflux condenser. DMAA: LA: VPE-201 = 84.95: 15: 0.05 And each monomer and a polymerization initiator were added so that it might become a total of 80 g, and also 103g of MeOH was added as a solvent, and it heated gradually and stirred by heating at 65 degreeC for 8 hours. Thereafter, the solvent was replaced with methyl ethyl ketone (MEK), and the mixture was further stirred with heating at 80 ° C. for 6 hours. After cooling, the reaction solution was dropped into a sufficient amount of water, and the deposited precipitate was collected by filtration and dried under reduced pressure to obtain copolymers 1 to 10.
The compounds used are as follows:
DMAA: dimethylacrylamide LA: lauryl acrylate VPE-201: azo group-containing polyoxyethylene The azo group-containing polyoxyethylene compound is, for example, “VPE” (VPE-0201, VPE-0401, VPE-0601, etc.) series (Wako Pure Chemical Industries, Ltd.) (Available from Kogyo Co., Ltd.) and the like, and are commercially available.

<Preparation of amphiphilic dispersion of silver halide grain emulsion>
To 7.5 g of the above-mentioned copolymer for amphiphilic dispersion, 67.5 g of methanol was added and dissolved at 47.5 ° C. with stirring for 30 minutes. Thereto was added dropwise 32 g of the silver halide grain emulsion adjusted to 45 ° C. over 2 minutes, and the mixture was further stirred for 60 minutes. Thereafter, an appropriate amount of water is added, the temperature is lowered to 40 ° C., and then the liquid left for 60 minutes is separated into two layers. The supernatant of the liquid was removed, 550 g of MEK was added to the remaining liquid, and distilled under reduced pressure until the water content in the liquid became less than 5%. Finally, MEK was added so that the total amount was 207 g to obtain an amphiphilic dispersion of a silver halide grain emulsion.

<Preparation of powdered aliphatic carboxylic acid silver salt>
An aliphatic carboxylic acid silver particle salt was prepared using an apparatus as shown in FIG. In tank 11, an aliphatic carboxylic acid mixture (molar composition ratio: behenic acid / arachidic acid / stearic acid = 49/29/19) and an aliphatic carboxylic acid mixture (molar composition ratio: behenic acid / arachidic acid / Stearic acid = 90/5/3) 1,850 g was mixed and 90% of the pure water amount adjusted to a concentration of 5% was stirred at 85 ° C. After the addition over a period of 60 minutes, the reaction was allowed to proceed for 60 minutes to obtain an aqueous potassium aliphatic carboxylate solution. Finally, additional pure water was added so that the concentration of the aliphatic potassium carboxylate aqueous solution was 5%. Further, 38,300 g of a 5% silver nitrate aqueous solution was prepared in the tank 12 and kept at 10 ° C. The above aliphatic potassium carboxylate aqueous solution and silver nitrate aqueous solution were simultaneously added at a constant addition rate over a period of 4 minutes and stocked in the tank 13. During the addition, the tank 13 was kept at 35 ° C. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water at 25 ° C. until the conductivity of the permeated water reached 30 μS / cm. The obtained dehydrated cake was dried at 50 ° C. to obtain a dried powder of aliphatic carboxylic acid silver salt particles. In the figure, 17 is a flow meter and 15 is a pump. In addition, 88%, 90%, and 97% silverization ratio solutions were prepared by adding 996 ml, 988 ml, and 1065 ml of potassium hydroxide aqueous solution, respectively, by the same method as described above.

<Preparation of aliphatic carboxylic acid silver salt dispersion emulsion>
49 g of polyvinyl butyral (Sekisui Chemical Co., Ltd .: ESREC B / BL-SHP) dissolved in 1,300 g of MEK and stirred with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN 500 g of powdered aliphatic carboxylic acid silver salt Was added gradually and mixed well to prepare a preliminary dispersion. After the total amount of powdered aliphatic carboxylic acid silver salt was added, stirring was performed at 1,500 rpm for 15 minutes. This pre-dispersed liquid is a media type disperser DISPERMAT filled with 80% of the internal volume of 0.5 mm zirconia beads (Toray Industries, Inc .: Treceram) so that the residence time in the mill is 1.2 minutes using a pump. An aliphatic carboxylic acid silver salt dispersion emulsion was prepared by supplying to SL-C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 9 m / sec. The solid content concentration of the obtained aliphatic carboxylic acid silver salt dispersion emulsion was about 27%.

  In the case of an aliphatic carboxylic acid silver salt that does not use a photosensitive silver halide grain emulsion when preparing the aliphatic carboxylic acid silver salt, the above-mentioned silver halide grain parent is added to 1,670 g of the obtained aliphatic carboxylic acid silver dispersion. 157 g of the medium dispersion was added, and the photosensitive layer coating solution described later was subsequently prepared.

<Preparation of photosensitive layer coating solution>
The same amount of MEK was added to 1670 g of the aliphatic carboxylic acid silver salt dispersion emulsion, and the mixture was kept at 18 ° C. with stirring, and 1.2 g of bis (dimethylacetamide) dibromobromate (11% methanol solution) was added. Stir for 1 hour. Subsequently, 15.1 g of calcium bromide (11% methanol solution) was added and stirred for 30 minutes. Further, an infrared sensitizing dye solution was 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., 375 g of polyvinyl butyral resin powder was added and dissolved. After confirming dissolution, 19.8 g of tetrachlorophthalic acid (13% MEK solution) was added, and the following additives were added at intervals of 15 minutes while continuing stirring to obtain a photosensitive layer coating solution.

Phthalazine 12.4g
Desmodur N3300 (manufactured by Mobay: polyfunctional aliphatic isocyanate)
17.6g
Leuco dye-1 1.4g
0.6 g of leuco dye-2
Antifoggant solution below 180.0g
Developer solution below 800.0g
<Preparation of infrared sensitizing dye solution>
400 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- (4-methylbenzenesulfonyloxy) ) 2.5 g of benzene carboxylate (sensitizing dye solubilizer) was dissolved in 135 g of MEK to prepare an infrared sensitizing dye solution.

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

<Preparation of developer solution>
0.35 mol of the following reducing agent (an equimolar mixture), 9 g of 4-methylphthalic acid and 0.7 g of Dye-A were dissolved in MEK and finished to 800 g to obtain a developer solution.

(Preparation of surface protective layer coating solution)
MEK 1056g
148 g of cellulose acetate propionate (Eastman Chemical Co., Ltd .: CAP141-20)
Polymethylmethacrylate (Rohm and Haas, Paraloid A21)
6g
Matt dispersion (silica with an average particle size of 4 μm with a dispersion of 10%, solid content concentration of 1.7%)
170g
Crosslinking agent (CH ₂ ═CHSO ₂ CH ₂ ) ₂ CH (OH) 3.6 g
Benzimidazole 2g
Fluorocarbon surfactant _{C 9 F 17 O (CH 2} CH 2 O) 23 C 9 F 17 5.4g
Fluorosurfactant LiO ₃ S (CF ₂ ) ₃ SO ₃ Li 0.12 g
(Preparation of backcoat layer coating solution)
MEK 1350g
121 g of cellulose acetate propionate (manufactured by Eastman Chemical Co .: CAP482-20)
Dye-A 0.23g
Dye-B 0.62g
Fluorine acrylic copolymer (Daikin Kogyo Co., Ltd .: Optoflon FM450)
1.21 g
Amorphous saturated copolyester (Toyobo Co., Ltd .: Byron 240P) 18.1 g
Monodispersed three-dimensionally crosslinked spherical PMMA (polymethacrylate) with a monodispersity of 15%
(Average particle size) 2.4 g
Acrylic resin (Chemisnow MX-800S) 2.3g
Acrylic resin (Chemisnow MX-1500H) 0.06g
Surfactant C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₃ C ₉ F ₁₇ 5.21 g
Surfactant LiO ₃ S (CF ₂ ) ₃ SO ₃ Li 0.81 g

<Coating of photosensitive layer, surface protective layer, and back coat layer>
A photosensitive layer is applied on the photosensitive layer surface of the undercoated support so that the total silver amount is 1.2 g / m ² , and the wet weight is 23 g / m ^2. A surface protective layer was applied as a multilayer. Subsequently, a back coat layer was applied on the opposite back coat layer surface side undercoat so that the wet weight was 25 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.

<Evaluation of sample>
Evaluation is performed with the laser imager shown in FIG. 1 (equipped with a 786 nm semiconductor laser having a maximum output of 50 mW) and heat development simultaneously (temperatures 51, 52 and 53 in FIG. 1 are 100 ° C., 127 ° C. and 127 ° C., respectively). 2 seconds, 2 seconds and 6 seconds for a total of 10 seconds, or 2 seconds, 2 seconds and 4 seconds for a total of 8 seconds, respectively), and the resulting image is evaluated by a densitometer. went. Here, “thermal development at the same time as exposure” is a sheet photosensitive material made of a silver salt photothermographic dry imaging material, and a portion of the sheet that has been exposed at the same time is developed while being partially exposed. Means that will start. The distance between the exposed part and the developing part was 12 cm, and the linear velocity at this time was 30 mm / second. Further, the conveyance speed from the photosensitive material supply unit to the image exposure unit, the conveyance rate at the image exposure unit, and the conveyance rate at the heat development unit were each 30 mm / second. The exposure was performed stepwise while reducing the amount of exposure energy by logE = 0.05 step by step from the maximum output.

《Fog density, highest density》
The image obtained as described above was subjected to density measurement using a densitometer, and a characteristic curve including a horizontal axis—exposure amount and a vertical axis—density was created. In the characteristic curve, the fog density (minimum density) and the maximum density were measured. The maximum concentration was expressed as a relative value with 100 for each sample 1.

<Raw preservation, image preservation>
The storability of the raw sample showed the difference between the fog density value after the unexposed sample was stored in an environment of 40 ° C. for 20 days and the fog density value of the evaluation sample. The image storability showed the highest density retention when the developed evaluation sample was stored at 50 ° C. for 5 days in a light-shielded state.

  The above evaluation results are summarized in Table 1 and Table 2.

  As shown in Tables 1 and 2, by using the means of the present invention, a high maximum density can be obtained even in short-time heat development while the fog density is as low as 0.17, and before the heat development. It is possible to provide a silver salt photothermographic dry imaging material that hardly increases fogging during storage and has excellent stability of a silver image after heat development.

The figure which shows the fatty-acid silver salt manufacturing apparatus based on this invention roughly

Explanation of symbols

21, 22, 23, 26 Tank 24, 25 Mixing device 27 Flow meter 28 Pump

Claims (11)

In a silver salt photothermographic dry imaging material having a photosensitive layer containing a photosensitive silver halide grain, a non-photosensitive aliphatic carboxylic acid silver salt, and a silver ion reducing agent, the non-photosensitive aliphatic carboxylic acid silver salt is A silver salt photothermographic dry imaging material manufactured using a plurality of different aliphatic carboxylic acid mixtures having different behenic acid content ratios as raw materials. The non-photosensitive aliphatic carboxylic acid silver salt has a dry aliphatic carboxylic acid silver salt (powder crystal state) interlayer distance of 57 to 60 mm and an X-ray diffraction peak half width of 0.15 to 0.40. The silver salt photothermographic dry imaging material according to claim 1, wherein The silver salt photothermographic image according to claim 1 or 2, wherein 95% by mass or more of the constituent components of the aliphatic carboxylic acid mixture is composed of behenic acid, arachidic acid, and stearic acid. Dry imaging material. The at least one of the plurality of different aliphatic carboxylic acid mixtures contains 40 to 60% by mass of behenic acid, and the other contains 85 to 95% by mass of behenic acid. The silver salt photothermographic dry imaging material according to any one of 1 to 3. The non-photosensitive aliphatic carboxylic acid silver salt is a mixture ratio (mass ratio) of an aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid and an aliphatic carboxylic acid mixture containing 85 to 95% by mass of behenic acid. The silver salt photothermographic dry imaging material according to any one of claims 1 to 4, wherein the silver salt photothermographic dry imaging material is manufactured using 5: 1 to 1: 8. The silver salt photothermographic dry imaging material according to claim 5, wherein the mixing ratio is 1: 1 to 1: 4. The mixing ratio according to claim 6, wherein the aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid contains 10 to 30% by mass of stearic acid. Silver salt photothermographic dry imaging material. The mixture ratio according to claim 6, wherein the aliphatic carboxylic acid mixture containing 40 to 60% by mass of behenic acid contains 10 to 25% by mass of stearic acid. The silver salt photothermographic dry imaging material described. The manufacturing method of the silver salt photothermographic dry imaging material characterized by manufacturing the silver salt photothermographic dry imaging material as described in any one of Claims 1-8. In the image formation method based on digital image information, a silver image is formed using the silver salt photothermographic dry imaging material as described in any one of Claims 1-8, The image formation method characterized by the above-mentioned. In an image forming method based on digital image information, the silver salt photothermographic dry imaging material according to any one of claims 1 to 8 is exposed to a laser beam having a wavelength in a wavelength region of 780 to 820 nm, and subsequently. A silver image is formed by heat development at a temperature of 110 to 150 ° C. for 10 seconds or less to form a silver image.

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