JP2007212838A - Silver salt photothermographic dry imaging material, sheetlike photosensitive material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material excellent in image quality and particularly having high maximum density and excellent sharpness, a sheetlike photosensitive material and an image forming method. <P>SOLUTION: The silver salt photothermographic dry imaging material has a photosensitive layer containing an organic silver salt, silver halide grains, a binder and a reducing agent on one and the same surface of a support, wherein the photosensitive layer has a dry film thickness of 8.0-16.0 μm and an average gradation (γ value) at an optical density of 1.2 on a photographic characteristic curve being 4.1-6.0, and the reducing agent is a compound represented by formula (RD1), wherein X<SB>1</SB>represents chalcogen or CHR<SB>1</SB>, R<SB>1</SB>represents H, halogen, alkyl, alkenyl, aryl or a heterocyclic group; R<SB>2</SB>represents alkyl, two symbols R<SB>2</SB>may be the same or different but at least one of those is secondary or tertiary alkyl; R<SB>3</SB>represents H or a group substitutable on the corresponding benzene ring; R<SB>4</SB>represents a group substitutable on the corresponding benzene ring; and m and n each represent an integer of 0-2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a silver salt photothermographic dry imaging material containing an organic silver salt, silver halide grains, a binder and a reducing agent is irradiated on a support and a laser beam from a semiconductor laser, followed by heat development. The present invention relates to an image forming method for recording an image.

  Conventionally, in the fields of medical treatment and printing plate making, waste liquid from wet processing of image forming materials has been a problem in terms of workability. In recent years, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental conservation and space saving. ing. Therefore, silver salt photothermographic dry imaging materials capable of forming an image only by applying heat have been put into practical use and are rapidly spreading in the above fields.

  Silver salt photothermographic dry imaging materials themselves have been proposed for a long time (see, for example, Patent Documents 1 and 2).

  This silver salt photothermographic dry imaging material is usually processed by a heat development processing apparatus called a heat development processor that forms an image by applying stable heat to the silver salt photothermographic dry imaging material. As described above, with the rapid spread in recent years, a large amount of this heat development processing apparatus has been supplied to the market. In recent years, there has been a demand for a compact laser imager and quick processing.

  For this purpose, it is essential to improve the characteristics of silver salt photothermographic dry imaging materials. In order to obtain a sufficient density of a photographic image even if rapid processing is performed, the covering power is increased by increasing the number of coloring points by using silver halide grains having a small average grain size (for example, Patent Document 3). 4), or a highly active reducing agent having a secondary or tertiary alkyl group (see, for example, Patent Document 5), or a development accelerator such as a hydrazine compound, a vinyl compound, a phenol derivative, or a naphthol derivative. It is effective to use (for example, refer to Patent Documents 6 and 7). However, when a development accelerator is used, there is a problem that image storability and raw storability deteriorate. Further, a reducing agent that can maintain a high maximum concentration and at the same time has excellent storage stability is disclosed (for example, see Patent Documents 8 and 9).

On the other hand, as a response from the apparatus side to the rapid processing, a technique of performing exposure while heating on a heat developing drum or performing heat development simultaneously with exposure is disclosed. (For example, refer to Patent Documents 10 to 13.) Further, a technique using a silver salt photothermographic dry imaging material having a γ value of 2.0 to 4.0 is disclosed in order to eliminate development unevenness that easily occurs during rapid processing. Yes.
US Pat. No. 3,152,904 (Claims) US Pat. No. 3,457,075 (Claims) JP-A-11-295844 (Claims) JP 11-352627 A (Claims) JP 2001-209145 A (Claims) JP 2002-006443 A (Claims) Japanese Patent Laid-Open No. 2003-065558 (Claims) JP, 2004-004650, A (Claims) JP 2004-004767 A (Claims) JP 10-115889 A (Claims) JP 2002-162692 A (Claims) JP-A-2004-85763 (Claims) JP 2004-151676 A (Claims)

  When the thermal development apparatus is downsized and rapid processing is performed, the maximum density after thermal development is not sufficient particularly for mammography even when the above-described conventional technique is used, and the γ value is set to 2.0 to 4.0. It has been found that even when the development unevenness after heat development is improved, the sharpness of the image after heat development is not at a sufficient level.

  The present invention has been made in view of the above-mentioned background circumstances, and an object of the present invention is a silver salt photothermographic dry imaging material and sheet photosensitive material excellent in image quality, particularly high in the highest density and excellent in sharpness. And providing an image forming method.

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

  1. A photosensitive layer containing an organic silver salt, silver halide grains, a binder and a reducing agent is provided on the same side of the support, and the dry thickness of the photosensitive layer is 8.0 μm or more and 16.0 μm or less. The average gradation (γ value) at an optical density of 1.2 of the photographic characteristic curve is 4.1 to 6.0, and the reducing agent is a compound represented by the following general formula (RD1) Silver salt photothermographic dry imaging material.

[Wherein, X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ₂ represents an alkyl group, which may be the same or different, but at least one is a secondary or tertiary alkyl group. R ₃ represents a hydrogen atom or a group that can be substituted on a benzene ring. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
2. R _{3 of the} compound represented by the general formula (RD1) may form a hydroxyl group by deprotecting at least one group having 1 to 20 carbon atoms having a hydroxyl group as a substituent. 2. The silver salt photothermographic dry imaging material according to 1 above, which is an alkyl group having 1 to 20 carbon atoms having a group as a substituent.

  3. 3. The silver salt photothermographic dry imaging material as described in 1 or 2 above, wherein the photosensitive layer contains a silver saving agent.

  4). 4. The silver salt photothermographic dry imaging material according to any one of 1 to 3 above, wherein the maximum value of the image density after heat development is 3.8 or more and 5.0 or less.

  5. 5. The silver salt photothermographic dry imaging material according to any one of 1 to 4, wherein the photosensitive layer has a dry film thickness of 9.0 μm or more and 15.0 μm or less.

  6). 6. The silver salt photothermographic dry imaging material according to any one of 1 to 5, wherein the average gradation (γ value) is 4.5 to 5.5.

  7). The silver salt as described in any one of 1 to 6 above, wherein the silver halide grains contained in the photosensitive layer contain silver iodide in a proportion of 5 mol% to 100 mol%. Photothermographic dry imaging material.

  8). 8. A sheet photosensitive material prepared by cutting the silver salt photothermographic dry imaging material according to any one of 1 to 7 into a sheet shape.

  9. 9. An image forming method comprising conveying the sheet photosensitive material described in 8 above while heating at a conveying speed of 30 to 200 mm / sec.

  10. 9. The image forming method according to claim 8, wherein a part of a sheet of the sheet photosensitive material according to 8 is exposed, and at the same time, development is started on a part of the sheet photosensitive material that has already been exposed.

  11. 9. An image forming method, wherein the sheet photosensitive material described in 8 is developed by a laser imager in which a distance between an exposure part and a development part is 0 cm or more and 50 cm or less.

  12 9. An image forming method comprising heat-developing the sheet photosensitive material described in 8 above with a laser imager at a heating time of 1 second to 10 seconds.

13. Image forming method characterized by footprint the photothermographic sheet material according to the 8 to heat developed by the laser imager is 0.25 m ² or more 0.40 m ² or less.

  According to the present invention, there is provided a silver salt photothermographic dry imaging material, a sheet photosensitive material and an image forming method which have a high maximum image density and excellent sharpness even when rapidly developed with a small laser imager. be able to.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  Hereinafter, the constituent elements of the present invention will be sequentially described.

(Gamma value)
Photographic Characteristic Curve In the present invention, the photographic characteristic curve represents the relationship between the optical density, that is, the scattered light photographic density (D), on the horizontal axis and the common logarithm (logE) of the exposure amount, which is exposure energy, on the horizontal axis. The D-log E curve. The gamma (γ) value is a tangent slope at the optical density D = 1.2 on the characteristic curve (tan θ when the angle between the tangent and the horizontal axis is θ).

  It has been conventionally known that when the gamma (γ) value is high, the image quality such as the sharpness and contrast of the image is improved, but the image density unevenness is deteriorated. A technique for preventing minute development unevenness due to shortening of processing time by using a silver salt photothermographic dry imaging material having a gamma value of 2.0 to 4.0 at an optical density 1.2 of a photographic characteristic curve is disclosed (Patent Document 13). As described above, the sharpness and maximum density of the image are not sufficient, and are not sufficient particularly for mammography. However, the dry thickness of the photosensitive layer is 8.0 μm or more and 16.0 μm or less, the compound of the general formula (RD1) is used as the reducing agent, and the gamma value is in a specific range of 4.1 to 6.0. Surprisingly, it has been found that the sharpness and the maximum density of the image are remarkably improved and have sufficient characteristics as a silver salt photothermographic dry imaging material for mammography. The gamma value at an optical density of 1.2 in the photographic characteristic curve is preferably 4.3 to 5.7, particularly preferably 4.5 to 5.5. On the other hand, if the gamma value at an optical density of 1.2 is less than 4.1, the image density and sharpness are insufficient and an image with good image quality cannot be obtained, and the gamma value at an optical density of 1.2 is 6.0. If it exceeds 1, heat development unevenness due to high-speed conveyance tends to occur.

In the present invention, in order to adjust the gamma value to 4.1 to 6.0, it can be easily adjusted by appropriately combining the following techniques.
1) Change the type and addition amount of developer 2) Change the type and addition amount of silver saving agent 3) Change the addition amount and average grain size of silver halide 4) Spectral sensitizing dye to be adsorbed on silver halide 5) The method of chemical sensitization of silver halide and the degree of ripening are changed.

  The dry thickness of the photosensitive layer is preferably from 9.0 μm to 15.0 μm, more preferably from 9.5 μm to 14.0 μm, and more preferably from 10.0 μm to 13.0 μm. It is particularly preferred. The total dry film thickness of the photosensitive layer and the non-photosensitive layer provided on at least one surface of the support of the silver salt photothermographic dry imaging material is preferably 12.0 μm or more and 19.0 μm or less, and 14.0 μm. As mentioned above, it is especially preferable that it is 18.0 micrometers or less. In order to improve image density unevenness and sharpness after heat development, the maximum value of image density after heat development is preferably 3.8 or more and 5.0 or less, but 4.0 or more and 4.8 or less. It is more preferable that it is 4.2 or more and 4.6 or less.

(Organic silver salt)
The organic silver salt according to the present invention is a non-photosensitive organic silver salt that can function as a supply source for supplying silver ions for forming a silver image in a photosensitive layer of a silver salt photothermographic dry imaging material. .

  That is, the organic silver salt according to the present invention was heated to 80 ° C. or higher in the presence of photosensitive silver halide grains (photocatalyst) having a latent image formed by exposure on the grain surface and a reducing agent. In the thermal development process, the silver salt functions as a silver ion supply source and can supply silver ions and contribute to silver image formation.

  As such a non-photosensitive organic silver salt, conventionally, silver salts of organic compounds having various chemical structures are known. For example, paragraphs “0048” to “0049” of JP-A-10-62899, European Patent Application Publication No. 803,764A1, page 18, line 24 to page 19, line 37, European Patent Application Publication No. 962,812A1, Japanese Patent Application Laid-Open No. 11-349591, Japanese Patent Application Laid-Open No. 2000- 7683, 2000-72711, 2002-23301, 2002-23303, 2002-49119, 196446, European Patent Application No. 1246001A1, European Patent Application Publication No. 1258775A1, JP 2003-140290 A, JP 2003-195445 A, 2003-295378, JP same 2003-295379, JP same 2003-295380, JP same 2003-295381 JP, described in JP-A No. 2003-270755 Publication.

  In the present invention, a silver salt of an aliphatic carboxylic acid, particularly, having 10 to 30 carbon atoms, preferably in combination with or without using various organic silver salts disclosed in the above-mentioned patent publications, etc. A silver salt of 15 to 28 long chain aliphatic carboxylic acid can be used. The molecular weight of the aliphatic carboxylic acid for producing the silver salt is preferably 200 to 500, more preferably 250 to 400. Preferred examples of the aliphatic carboxylic acid silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and a mixture thereof. Including.

  In the present invention, among these aliphatic carboxylates, the silver behenate content is preferably 50 mol% or more, more preferably 80 mol% or more and 100 mol% or less, based on the total aliphatic carboxylate silver. It is preferable to use a fatty acid silver of 90 mol% or more and 99.99 mol% or less. 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.

  Prior to the preparation of the aliphatic carboxylic acid silver salt, it is necessary to prepare an alkali metal salt of an aliphatic carboxylic acid. In this case, 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, for example, potassium hydroxide, but it is also preferable to use sodium hydroxide and potassium hydroxide in combination. The combined ratio is preferably such that the molar ratio of both of the above-mentioned hydroxide salts is in the range of 10:90 to 75:25. When used in the above range when reacted with an aliphatic carboxylic acid to form an alkali metal salt of an aliphatic carboxylic acid, the viscosity of the reaction solution can be controlled in a good state.

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

  The average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt means the diameter of the sphere having the same volume as the volume of one particle of the non-photosensitive aliphatic carboxylic acid silver salt. The particle volume can be obtained from the projected area and thickness of the particles observed by the above, and the diameter when converted to a sphere having the same volume as that volume can be obtained by averaging. In order to control the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt, as described above, the preparation of the aliphatic carboxylic acid silver salt can be adjusted by increasing the ratio of potassium salt, or the photosensitive emulsion dispersion This can be easily performed by appropriately adjusting the particle diameter, mill peripheral speed, and dispersion time of the zirconia beads used during dispersion of the liquid. In the present invention, the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt is preferably 0.05 to 0.50 μm, more preferably 0.005 μm in order to obtain a sufficient density after heat development. The thickness is 10 to 0.45 μm, particularly preferably 0.15 to 0.40 μm.

  Examples of organic silver that may be used in addition to the non-photosensitive aliphatic carboxylic acid silver salt used in the present invention include organic silver salts having a core-shell structure (Japanese Patent Laid-Open No. 2002-23303), polyvalent A silver salt of carboxylic acid (EP1246001 and JP2004-061948) and a polymer silver salt (JP2000-292881, JP2003-295378 to 2003-295281) can also be used.

  The shape of the aliphatic carboxylic acid silver salt that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a flake shape. In the present invention, flake-shaped aliphatic carboxylic acid silver salts and short needle-shaped or rectangular parallelepiped-shaped aliphatic carboxylic acid silver salts having a major axis / minor axis length ratio of 5 or less are preferably used.

  In the present specification, the scaly organic silver salt is defined as follows. The organic silver salt is observed with an electron microscope, the shape of the organic silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (even though c is the same as b) Good)), and calculate with the shorter numbers a and b, and find x as follows.

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

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

  The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. It is as follows. The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to temporal change of fluctuation of the scattered light. Can be sought.

  Known methods and the like can be applied to the production of organic silver used in the present invention and the dispersion method thereof. For example, 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 addition, for example, the above-mentioned Japanese Patent Application Laid-Open No. 10-62899, European Patent Application Publication No. 803,763A1, European Patent Application Publication No. 962,812A1, Japanese Patent Application Laid-Open No. 2001-167022, and Japanese Patent Application Laid-Open No. 2000-16722. 7683, 2000-72711, 2001-163889, 2001-163890, 2001-163827, 2001-33907, 2001-188313, 2001-83652. No. 2002, No. 2002-6442, No. 2002-31870, No. 2003-280135, No. 2005-157190, etc. can be referred to.

  A photosensitive silver salt such as photosensitive silver halide grains can coexist when the organic silver salt is dispersed. However, when silver halide grains are allowed to coexist at the time of dispersion of the organic silver salt, fog is increased and sensitivity is remarkably lowered. Therefore, it is more preferable that silver halide grains are not substantially contained at the time of dispersion. In the present invention, the amount of silver halide grains in the aqueous dispersion to be dispersed is preferably 1 mol% or less, more preferably 0.1 mol% or less with respect to 1 mol of the organic silver salt in the liquid. More preferably, the active addition of silver halide grains is not performed.

  In the present invention, it is possible to produce a silver salt photothermographic dry imaging material by mixing an organic silver salt aqueous dispersion and a photosensitive silver halide particle dispersion, but the mixing ratio of the organic silver salt and the photosensitive silver salt is Although it can be selected according to the purpose, the ratio of the photosensitive silver halide grains to the organic silver salt is preferably in the range of 1 to 30 mol%, more preferably 2 to 20 mol%, and particularly preferably 3 to 15 mol%. Mixing two or more kinds of organic silver salt dispersions and two or more kinds of silver halide grain dispersions when mixing is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present invention can be used in a desired amount, but the silver amount is preferably 0.1 to 5 g / m ² , more preferably 0.3 to 3 g / m ² , still more preferably 0.5 to ² g / m ² . m ² .

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

  The silver halide grains themselves 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 an acidic method, a neutral method, an ammonia method, etc. may be used, and a method of reacting a soluble silver salt and a soluble halogen salt may be any one of a one-side mixing method, a simultaneous mixing method, a combination thereof, and the like. 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 performed continuously at a time, or nucleation (seed grain) formation and grain growth are performed separately. The method may be used. The controlled double jet method in which the particle formation is controlled by controlling the pAg, pH, etc., which are particle formation conditions, is preferable because the particle shape and size can be controlled. For example, when performing a method in which nucleation and particle growth are performed separately, first, an aqueous silver salt solution and an aqueous halide solution are uniformly and rapidly mixed in an aqueous gelatin solution to produce nuclei (seed particles) (nucleation process). Then, silver halide grains are prepared by a grain growth process in which grains are grown while supplying an aqueous silver salt solution and an aqueous halide solution under controlled pAg, pH, and the like. After the formation of grains, a desired silver halide emulsion can be obtained by removing unnecessary salts and the like by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, or an electrodialysis method. .

  In the present invention, the grain size distribution of silver halide grains is preferably monodispersed. The term “monodispersed” as used herein 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 grains, spherical grains, rod-like grains, potato-like grains, etc. Among these, cubic, octahedral, 14 Planar and tabular silver halide grains are preferred.

  The average aspect ratio when using tabular silver halide grains is preferably 1.5 or more and 100 or less, more preferably 2 or more and 50 or less. 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.

  There is no particular limitation on the crystal habit on the outer surface of the silver halide grain, but when using a sensitizing dye having crystal habit (plane) selectivity 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. 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.

  In the present invention, 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 hydrolyzed by adding gelatin-degrading enzyme to a commonly used gelatin aqueous solution with an average molecular weight of about 100,000, heating 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 at the time of nucleation is preferably 5% by mass or less, and more preferably 0.05 to 3.0% by mass.

  As the silver halide grains used in the present invention, it is preferable to use a compound represented by the following general formula at the time of forming the grains.

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 comprises a step of producing a gelatin aqueous solution, a step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, and an emulsion. 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 on a support. This is described in Japanese Patent Publication No. 44-9497. The polyethylene oxide compound represented by the above general formula 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 represented by the above general formula may be present at the time of nucleation and is preferably added in advance to the dispersion medium before nucleation, but may be added during nucleation or You may add and use for the silver salt aqueous solution and halide aqueous solution which are used at the time of formation. Preferably, it is used by adding 0.01 to 2.0% by mass to the halide aqueous solution or both aqueous solutions. Further, the compound represented by the above general formula is preferably present for a time of at least 50% of the nucleation step, and more preferably for a time of 70% or more. The compound represented by the above general formula 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 rising pattern (for example, 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 reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can usually be set in the range of 1.7 to 10, but the pH on the alkali side broadens the particle size distribution of the nuclei to be formed, and is preferably pH 2 to 6. 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.

  In the present invention, 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, when it is not a normal crystal, 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 was performed using an electron micrograph, and the average particle size was determined by averaging the measured values of the particle size 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, the image density can be improved, and the decrease in image density over time can be improved (smaller). 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 preferable that the photosensitive layer is composed of two or more layers, and the silver halide grain emulsions having the two average grain sizes are separately contained in each layer.

(Silver halide grains having a silver iodide content of 5 mol% to 100 mol%)
As the silver halide grains according to the present invention, silver halide grains containing silver iodide can be preferably used. As the halogen composition, the silver iodide content is preferably 5 mol% or more and 100 mol% or less. More preferably, they are 40 mol% or more and 100 mol% or less, More preferably, they are 70 mol% or more and 100 mol% or less, Especially preferably, they are 90 mol% or more and 100 mol% or less. 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 with 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.

  Examples of the method for introducing silver iodide into the silver halide grains according to the present invention include 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 iodine. A method of adding at least one fine particle of silver chlorobromide and a method using an iodide ion releasing agent described in JP-A-5-323487 and JP-A-6-11780 are preferred.

  The silver halide grains according to the present invention preferably exhibit direct transition absorption derived from the silver iodide crystal structure at a wavelength between 350 nm and 440 nm. Whether these silver halides have light absorption of direct transition can be easily distinguished by the fact that exciton absorption due to direct transition is observed in the vicinity of 400 nm 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 methanol, acetone, methyl ethyl ketone, diethyl ketone and the like 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 polymers described in “0018” of JP-A-2005-316054.

  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-i-propylacrylamide 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 described in “0022” to “0024” of JP-A-2005-316054 are particularly preferable.

  Moreover, as a monomer of a commercial item, the monomer etc. which were described in "0025" of Unexamined-Japanese-Patent No. 2005-316054 are mentioned.

  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 the Society of Polymer Science, Kyoritsu Shuppansha, 1995. It is also described in detail in Yuza 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 thereof include compounds described in “0029” and “0030” of JP-A-2005-316054. The polymerization initiator, the polymerization inhibitor, the isoelectric point of the polymer, the kind of the solvent used during the polymerization, the molecular weight of the polymer, and the like are described in “0031” to “0039” of JP-A-2005-316054.

  Although the specific example of an amphiphilic polymer is shown below, it is not limited to these.

(Chemical sensitization)
The photosensitive silver halide grains according to the present invention can be chemically sensitized. For example, use of a compound that releases a chalcogen such as sulfur, selenium, tellurium, or a noble metal ion that releases a noble metal ion such as gold ion by the methods described in JP-A Nos. 2001-249428 and 2001-249426 Thus, it is possible to form and impart a chemical sensitization center (chemical sensitization nucleus) capable of capturing electrons or holes generated by photoexcitation of photosensitive silver halide grains or spectral sensitizing dyes 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 adsorbing to silver halide 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 among them, at least one compound having a structure in which a chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond It is preferable. In particular, a thiourea derivative having a heterocyclic group and a triphenylphosphine sulfide derivative are preferred.

  As a method for 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 (reference: (1) T Edited by H. James “The Theory of the Photographic Process” 4th edition, Macmillan Publishing Co., Ltd., 1977, (2) The Japan Photographic 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 organic 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.

  The environmental conditions for chemical sensitization are not particularly limited, but in the presence of a compound capable of annihilating or reducing the size of silver chalcogenide or silver nuclei on 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, more preferably 5 to 8, and the temperature increases at 30 ° C. or lower. It is preferable to give a feeling.

  In addition, chemical sensitization using these organic sensitizers is preferably performed 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 an adsorptivity to silver halide, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved. Although the spectral sensitizing dye will be described later, preferred examples of the heteroatom-containing compound having adsorptivity to silver halide include nitrogen-containing heterocyclic compounds described in JP-A-3-24537. In the nitrogen-containing heterocyclic compound, examples of the heterocyclic ring include pyrazole ring, pyrimidine ring, 1,2,4-triazole ring, 1,2,3-triazole ring, 1,3,4-thiadiazole ring, 1,2 , 3-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,3,4-tetrazole ring, pyridazine ring, 1,2,3-triazine ring, these rings Can be mentioned, for example, a triazolotriazole ring, a diazaindene ring, a triazaindene ring, a pentaazaindene ring, and the like. A heterocyclic ring in which a monocyclic heterocyclic ring and an aromatic ring are condensed, for example, a phthalazine ring, a benzimidazole ring, an indazole ring, a benzthiazole ring, or the like can also be applied.

  Of these, an azaindene ring is preferable, and an azaindene compound having a hydroxyl group as a substituent, for example, a hydroxytriazaindene, tetrahydroxyazaindene, hydroxypentaazaindene 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 amount of the heterocyclic compound added 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 per mole of silver halide. It is in the range of ˜1 mol, preferably in the range of 10 ⁻⁴ to 10 ⁻¹ mol.

  The photosensitive silver halide according to the present invention 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-described sensitization methods, reduction sensitization methods and the like can also be used. Examples of reduction sensitization shell-like compounds include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, A borane compound, a silane compound, a polyamine compound, or 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 may be formed in the presence of an aliphatic carboxylic acid silver salt, or in the absence of the organic silver salt, A mixture of the two may be used.

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

(Spectral sensitization)
The photosensitive silver halide in the present invention 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-63-159841, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, JP-A-63-15245, US Pat. No. 4,639,414, No. 4,740,455, No. 4,741,966, No. 4,751,175, No. 4,835,096 can be used.

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

  Useful cyanine dyes are, for example, 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 sensitization disclosed in US Pat. Nos. 4,536,473, 4,515,888, 4,959,294, and the like. Examples include dyes.

  In the silver salt photothermographic dry imaging material used in the thermal development method of the present invention, the sensitizing dye represented by the general formula (1) and the general formula (in general formula (1) described in US Patent Publication No. 2004-0224266) It is preferable to select and contain at least one of the sensitizing dyes represented by 2), among the sensitizing dyes represented by the general formula (5) and the general formula (6). It is more preferable to select and contain at least one selected from. It is particularly preferable to use the sensitizing dye represented by the general formula (5) and the sensitizing dye represented by the general formula (6) in combination for improving the exposure wavelength dependency at the time of exposure.

  The above-mentioned infrared sensitizing dyes are described in, for example, HM Hammer, The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanine Dies and Related Compounds, published by A. Weissberger ed. It can be easily synthesized by this method.

  These infrared sensitizing dyes may be added at any time after the silver halide is prepared. For example, silver halide grains or halogens may be added in a so-called solid dispersion state added to a solvent or dispersed in a fine particle form. It can be added to a light-sensitive emulsion containing silver halide grains / aliphatic carboxylic acid silver salt grains. 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. Thus, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved.

  In the present invention, one kind of spectral sensitizing dye may be used alone, but as described above, it is preferable to use a combination of plural kinds of spectral sensitizing dyes. The combination is often used for the purpose of supersensitization and enlargement or adjustment of the photosensitive wavelength region.

  The emulsion containing the photosensitive silver halide and the aliphatic carboxylic acid silver salt used in the silver salt photothermographic dry imaging material of the present invention is not only a sensitizing dye but also a dye having no spectral sensitizing action itself or visible light. In the emulsion, a substance that does not substantially absorb the color and expresses a supersensitization effect may be contained in the emulsion, whereby the silver halide grains may be supersensitized.

  Useful sensitizing dyes, combinations of dyes exhibiting supersensitization, and substances exhibiting supersensitization are described in RD17643 (issued in December, 1978), page 23, Section J, or Japanese Patent Publication No. 9-25500, 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. As supersensitizers, heteroaromatic mercapto represented by the following can be used. A compound or a mercapto derivative compound is preferred.

Ar-SM
[Wherein, 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. ]
Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzthiazole, naphthothiazole, benzoxazole, naphthoxazole, benzselenazole, benztelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine , Purine, quinoline, or quinazoline. However, other heteroaromatic rings are also included.

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

Ar-SS-Ar
[Ar in the formula has the same meaning as in the case of the mercapto compound represented above. ]
The heteroaromatic ring includes, for example, a halogen atom (for example, chlorine, bromine, iodine), a hydroxyl group, an amino group, a carboxyl group, and an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms). It may have a substituent selected from the group consisting of those having a carbon atom) and alkoxy groups (for example, those having 1 or more carbon atoms, preferably 1 to 4 carbon atoms).

  In addition to the supersensitizer described above, macrocycles having heteroatoms disclosed in JP-A No. 2001-330918 can also be used as the supersensitizer.

  The supersensitizer according to the present invention is preferably used in an amount of 0.001 to 1.0 mol per mol of silver in a photosensitive layer containing an organic silver salt and silver halide grains. Particularly preferred is an amount of 0.01 to 0.5 mole per mole of silver.

  In the present invention, it is necessary that the spectral sensitizing dye is adsorbed on the surface of the photosensitive silver halide grain to effect spectral sensitization, and that the spectral sensitizing effect should substantially disappear after the thermal development process. It is. Here, the spectral sensitization effect substantially disappears when the sensitivity of the imaging material obtained with a sensitizing dye, supersensitizer, etc. is the sensitivity when the spectral sensitization is not performed after the thermal development process. It means to decrease to 1.1 times or less.

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

(Reducing agent)
The reducing agent according to the present invention can reduce silver ions in the photosensitive layer and is also referred to as a developer. In the present invention, the compound represented by the general formula (RD1) is used as a silver ion reducing agent. The reducing agent represented by the general formula (RD1) may be one type or two or more types of reducing agents. Moreover, you may use together with the reducing agent which has another different chemical structure.

  In the present invention, the compound of (RD1) and the compound of the following general formula (RD2) can be used in combination in order to control the heat development characteristics.

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

In the general formula (RD1), X ₁ represents a chalcogen atom or CHR ₁ . The chalcogen atom is sulfur, selenium or tellurium, preferably a sulfur atom. R ₁ in CHR ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom or the like, and the alkyl group is preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, and hexyl. Alkenyl groups such as vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, Examples of the aryl group include a benzene ring and a naphthalene ring, and examples of the heterocyclic group include thiophene, furan, imidazole, pyrazole, and pyrrole.

  These groups may further have a substituent. Specific examples of the substituent include a halogen atom (fluorine, chlorine, bromine, etc.), an alkyl group (methyl, ethyl, propyl, butyl, pentyl, i-pentyl). , 2-ethylhexyl, octyl, decyl, etc.), cycloalkyl groups (cyclohexyl, cycloheptyl, etc.), alkenyl groups (ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl) -3-butenyl, etc.), cycloalkenyl groups (1-cycloalkenyl, 2-cycloalkenyl groups, etc.), alkynyl groups (ethynyl, 1-propynyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, etc.), alkylcarbonyloxy groups (Acetyloxy, etc.), alkylthio groups (methylthio, trifluoromethylthio, etc.), Sil group (acetyl group, benzoyl 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, sulfite group, sulfino group, alkylsulfonylaminocarbonyl group (methanesulfonylaminocarbonyl, ethanesulfonylaminocarbonyl etc.), alkylcarbonylaminosulfonyl group (acetamidesulfonyl, methoxyacetamidosulfonyl etc.), alkynyl Examples thereof include aminocarbonyl groups (acetamidocarbonyl, methoxyacetamidocarbonyl, etc.), alkylsulfinylaminocarbonyl groups (methanesulfinylaminocarbonyl, ethanesulfinylaminocarbonyl, etc.) and the like. Moreover, when there are two or more substituents, they may be the same or different. A particularly preferred substituent is an alkyl group.

R ₂ represents an alkyl group, at least one of which is a secondary or tertiary alkyl group. The alkyl group is preferably a substituted or unsubstituted one having 1 to 20 carbon atoms, specifically, methyl, ethyl, propyl, i-propyl, butyl, i-butyl, t-butyl, t-pentyl, t-amyl. , T-octyl, cyclohexyl, cyclopentyl, 1-methylcyclohexyl, 1-methylcyclopropyl and the like.

Although the substituent of the alkyl group is not particularly limited, for example, aryl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, acyl group, carbamoyl group , Ester groups, halogen atoms and the like. Or it may form a saturated ring with (R _{4) n} and (R _{4) m.} R ₂ is preferably a secondary or tertiary alkyl group, and preferably has 2 to 20 carbon atoms. A tertiary alkyl group is more preferable, t-butyl, t-amyl, t-pentyl and 1-methylcyclohexyl are more preferable, and t-butyl and t-amyl are most preferable.

R ₃ represents a hydrogen atom or a group that can be substituted on a benzene ring. Examples of groups that can be substituted on the benzene ring include halogen atoms such as fluorine, chlorine, bromine, alkyl groups, aryl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, amino groups, acyl groups, and acyloxy groups. , Acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, sulfonyl group, alkylsulfonyl group, sulfinyl group, cyano group, heterocyclic group and the like. Examples of R ₃ include methyl, ethyl, i-propyl, t-butyl, cyclohexyl, 1-methylcyclohexyl, 2-hydroxyethyl, 3-hydroxypropyl, and the like.

These groups may further have a substituent, and the substituents mentioned in the above R ₁ can be used as the substituent.

R ₃ is an alkyl group having 1 to 20 carbon atoms having a hydroxyl group as a substituent, or an alkyl group having 1 to 20 carbon atoms having a group capable of forming a hydroxyl group by being deprotected as a substituent. R ₃ is preferably an alkyl group having 3 to 10 carbon atoms having a hydroxyl group as a substituent, or a group having 3 to 10 carbon atoms having a substituent that can form a hydroxyl group by being deprotected. It is an alkyl group. When the carbon number of the alkyl group is within this range, it is preferable in that the image does not become hard and an image suitable for diagnosis within the range of the average gradation of 4.1 to 6.0 can be obtained. R ₃ is particularly preferably an alkyl group having 3 to 5 carbon atoms having a hydroxyl group as a substituent. Examples of R ₃ include 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl and the like. These groups may further have a substituent, and the substituents mentioned in the above R ₁ can be used as the substituent.

  The group that can be deprotected to form a hydroxyl group is preferably a group that forms a hydroxyl group by deprotection by the action of an acid and / or heat.

  Specifically, ether groups (methoxy groups, tert-butoxy groups, allyloxy groups, benzyloxy groups, triphenylmethoxy groups, trimethylsilyloxy groups, etc.), hemiacetal groups (tetrahydropyranyloxy groups, etc.), ester groups (acetyl) Oxy group, benzoyloxy group, p-nitrobenzoyloxy group, formyloxy group, trifluoroacetyloxy group, pivaloyloxy group, etc.), carbonate group (ethoxycarbonyloxy group, phenoxycarbonyloxy group, tert-butyloxycarbonyloxy group, etc.) ), Sulfonate groups (p-toluenesulfonyloxy group, benzenesulfonyloxy group etc.), carbamoyloxy groups (phenylcarbamoyloxy group etc.), thiocarbonyloxy groups (benzylthiocarbonyloxy group etc.), Ester group, sulfenates group (2,4-dinitrobenzene sulfenyl group and the like).

R ₃ is most preferably a primary alkyl group having 3 to 5 carbon atoms having a hydroxyl group or a precursor group thereof, such as 3-hydroxypropyl. The most preferred combination of R ₂ and R _3, R ₂ is a tertiary alkyl group (t-butyl, t-amyl, t-pentyl, 1-methylcyclohexyl, etc.) and, R ₃ is a hydroxyl group or its precursor group And a primary alkyl group having 3 to 10 carbon atoms (3-hydroxypropyl, 4-hydroxybutyl, etc.). A plurality of R ₂ and R ₃ may be the same or different.

R ₄ represents a hydrogen atom or a group that can be substituted on the benzene ring, and 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 atoms (chlorine, bromine, iodine, fluorine), alkoxy groups ( Methoxy Ethoxy, propyloxy, pentyloxy, cyclopentyloxy, hexyloxy, cyclohexyloxy, etc.), aryloxy groups (phenoxy, etc.), alkoxycarbonyl groups (methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl, etc.), aryloxycarbonyl groups ( Phenyloxycarbonyl, etc.), sulfonamide groups (methanesulfonamide, ethanesulfonamide, butanesulfonamide, hexanesulfonamide group, cyclohexanesulfonamide, benzenesulfonamide, etc.), sulfamoyl groups (aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl) , Butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pi Lysylaminosulfonyl, 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, hexane Amide, benzamide, etc.), sulfonyl group (methylsulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexyl) Sulfonyl, 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 Group, oxamoyl group and the like. These groups may be further substituted with these groups. n and m represent an integer of 0 to 2, and most preferably n and m are 0.

R ₄ may form a saturated ring with R ₂ and R ₃ . R ₄ is preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom. A plurality of R ₄ may be the same or different.

In general formula (RD2), R ₅ is the same group as R _1, and R ₈ is the same group as R ₄ . R ₆ represents an alkyl group, which may be the same or different, but is not a secondary or tertiary alkyl group.

R ₇ represents a hydrogen atom or a group that can be substituted on a benzene ring. Examples of groups that can be substituted on the benzene ring include halogen atoms such as fluorine, chlorine, bromine, alkyl groups, aryl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, amino groups, acyl groups, and acyloxy groups. , Acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, sulfonyl group, alkylsulfonyl group, sulfinyl group, cyano group, heterocyclic group and the like.

R ₇ is preferably methyl, ethyl, i-propyl, t-butyl, cyclohexyl, 1-methylcyclohexyl, 2-hydroxyethyl, 3-hydroxypropyl and the like. More preferred are methyl and 3-hydroxypropyl.

  The alkyl group is preferably a substituted or unsubstituted one having 1 to 20 carbon atoms, and specific examples thereof include methyl, ethyl, propyl, butyl and the like.

  Although the substituent of the alkyl group is not particularly limited, for example, aryl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, acyl group, carbamoyl group , Ester groups, halogen atoms and the like.

R ₆ may form a saturated ring with (R ₈ ) _n and (R ₈ ) _m . R ₆ is preferably methyl. Among the compounds represented by the general formula (RD2), compounds preferably used are compounds satisfying the general formula (S) and the general formula (T) described in EP 1,278,101, Specific examples include compounds (1-24), (1-28) to (1-54), and (1-56) to (1-75) described in p21 to p28.

  Specific examples of the compounds represented by general formula (RD1) and general formula (RD2) are shown below, but the present invention is not limited to these.

  These bisphenol compounds represented by the general formula (RD1) and general formula (RD2) can be easily synthesized by a conventionally known method.

  In the present invention, examples of the reducing agent that can be used in combination include US Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, RD17029 and 29963. And reducing agents described in JP-A-11-119372 and JP-A-2002-62616.

The amount of the reducing agent including the compound represented by the general formula (RD1) is preferably 1 × 10 ⁻² to 10 mol, particularly preferably 1 × 10 ^{−2 to} 1.5 mol, per mol of silver. It is.

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

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

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

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

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

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

(2) In addition, the CIE 1976 (L ^* a ^* b ^* ) color space is measured by measuring the optical densities of the silver salt photothermographic dry imaging materials at 0.5, 1.0, 1.5 and the lowest optical density. 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 of a ^* as a ^* and the vertical axis as b ^* is 0. It is preferably 998 to 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 ^*, a ^* , and 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 spectral colorimeter (manufactured by Minolta (former name): CM-3600d, etc.) to calculate u ^* , v ^* or a ^* , b ^* . The measurement conditions at that time are F7 light source as the light source, the viewing angle is 10 degrees, and the measurement is performed in the transmission measurement mode. Plot u ^* , v ^* or a ^* , b ^* measured on a graph with u ^* or a ^{* on} the horizontal axis and v ^* or b ^{* on the} vertical axis to obtain a linear regression line, and the coefficient of determination (multiple determination) Find R ² , intercept and slope.

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

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

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

  When performing rapid processing using a compact laser imager with a short cooling section length, there may be a problem that the silver color tone is greatly deviated from the neutral preferred color tone compared to the normal processing. In order to solve the problem, a compound (such as a leuco dye or a coupler compound) that forms an imagewise color during heat development to form a dye image is used in addition to the toning agent such as the phthalazine compound described above. Is preferred. As these compounds, a compound that develops color during thermal development and forms a dye image having a maximum absorption wavelength of 360 to 450 nm, or a color that forms color during thermal development and forms a dye image that has a maximum absorption wavelength of 600 to 700 nm or less. Although a compound is preferable, the case where both compounds are included is particularly preferable for obtaining a good silver tone. As these compounds, it is preferable to use couplers disclosed in JP-A No. 11-288057, European Patent No. 1,134,611A2, etc., or leuco dyes described in detail below.

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

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

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination of a plurality of types. In addition, the use of highly active reducing agents for rapid processing changes the color tone (especially yellowishness) depending on the amount and ratio of use, or uses fine silver halide grains to develop developed silver. In order to prevent the image from becoming excessively reddish, especially in the high density part where the density is 2.0 or more, the use of a leuco dye that develops yellow and cyan colors is used in combination. It is preferable to adjust the amount.

  The color density is preferably adjusted appropriately in relation to the color tone of the developed silver itself. In the present invention, the color tone is adjusted so as to have an image in the above preferable color tone range by developing the color so as to have a reflection optical density of 0.01 to 0.05 or a transmission optical density of 0.005 to 0.50. preferable. In the present invention, the sum of the maximum densities at the maximum absorption wavelength of the dye image formed by the leuco dye is preferably 0.01 or more and 0.50 or less, more preferably 0.02 or more and 0.30 or less, and particularly preferably It is preferable that the color is developed so as to have 0.03 or more and 0.10 or less. The maximum absorption wavelength of the dye image can be obtained by measuring the spectral absorption spectrum of the silver salt photothermographic dry imaging material after heat development.

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

[Wherein 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 represent a 2-hydroxyphenylmethyl group. There is never. 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. ]
Hereinafter, the compound of the general formula (YA) will be described in detail.

In General Formula (YA), 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 preferable, and steric rather than i-propyl. Are preferably large groups (i-propyl, i-nonyl, t-butyl, t-amyl, t-octyl, cyclohexyl, 1-methyl-cyclohexyl, adamantyl, etc.), among which secondary or tertiary 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 represented by R ₁₂ 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 represented by R ₁₂ 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 ₁₁ and R ₁₂ are not 2-hydroxyphenylmethyl groups.

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 substitutable on the benzene ring, and is, for example, the same group as described for the substituent R ₄ in the general formula (RD1). 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, among the compounds represented by the general formula (YA), the bisphenol compound represented by the following general formula (YB), which is particularly preferably used in the present invention, will be described.

[Wherein, 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 the substituent represented by R ₂₁ and R ₂₁ ′ include the same groups as the substituents exemplified in the description of R _{1 in} the general formula (RD1). 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, and examples of the substituent include the same groups as those described for R ₂ and R ₃ in the general formula (RD1).

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 in the description of the substituent in the general formula (RD1).

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 the substituents described in the description of R ₄ in formula (RD1).

  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, Examples thereof include compounds (ITS-1) to (ITS-12) described in paragraph “0026” of EP 1,211,093.

  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 hindered phenol compounds and compounds of the general formula (YB)) is usually 0.00001 to 0.01 mol, preferably 0. 0005 to 0.01 mol, more preferably 0.001 to 0.008 mol.

  Moreover, it is preferable that the addition amount ratio with respect to the sum total of the reducing agent represented by general formula (RD1) and (RD2) of yellow coloring leuco dye is 0.001-0.2 in molar ratio, 0.005 More preferably, it is -0.1. 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 yellow color-forming leuco dye is preferably 0.01 or more and 0.50 or less, more preferably It is preferable that the color is developed so as to have 0.02 to 0.30, particularly preferably 0.03 to 0.10.

(Cyan coloring leuco dye)
The silver salt photothermographic dry imaging material of the present invention preferably adjusts the 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.

  In the present invention, a color image forming agent whose absorbance at 600 to 700 nm is increased by oxidation is particularly preferably used as a cyan color-forming leuco dye. Examples of these compounds include compounds of general formula (I) to general formula (IV) described in JP-A-59-206831 (particularly compounds having λmax in the range of 600 to 700 nm) and JP-A-5-204087. Specifically, the compounds of (1) to (18) described in paragraphs “0032” to “0037”) and compounds of general formulas 4 to 7 in JP-A No. 11-231460 (specifically, paragraph “0105”). No. 1 to No. 79 compounds).

  Next, specific examples of the cyan color-forming leuco dye will be shown, but the present invention is not limited thereto.

  The addition amount of the cyan coloring leuco dye is usually 0.00001 to 0.05 mol / Ag1 mol, preferably 0.0005 to 0.02 mol / Ag1 mol, more preferably 0.001 to 0.01 mol. / Ag1 mol. The addition ratio of the cyan coloring leuco dye to the sum of the reducing agents represented by the general formulas (RD1) and (RD2) is preferably 0.001 to 0.2 in terms of molar ratio, and 0.005. More preferably, it is -0.1.

  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 or more and 0.50 or less, more preferably 0.02. It is preferable to develop the color so that it has a value of 0.30 or less, particularly preferably 0.03 or more and 0.10 or less.

  In the present invention, a subtle color tone can be adjusted by using a magenta color developing leuco dye or a yellow color developing leuco dye in addition to the cyan color developing leuco dye.

  As a method for adding the compounds represented by the general formulas (YA) and (YB) and the cyan color-forming leuco dye, they can be added in the same manner as the method for adding the reducing agent represented by the general formula (RD1). , Solution form, emulsified dispersion form, solid fine particle dispersion form, etc. may be contained in the coating solution by any method and contained in the silver salt photothermographic dry imaging material.

  The compounds of the general formulas (RD1), (RD2), general formulas (YA) and (YB) and the cyan color-forming leuco dye are preferably contained in a photosensitive layer (image forming layer) containing an organic silver salt. One may be contained in the photosensitive layer and the other may be contained in the non-photosensitive layer adjacent to the photosensitive layer, or both 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.

(binder)
In the silver salt photothermographic dry imaging material of the present invention, the photosensitive layer and the non-photosensitive layer according to the present invention can contain a binder for various purposes.

  The binder contained in the photosensitive layer according to the present invention can carry an organic silver salt, silver halide grains, a reducing agent, and other components. Suitable binders are transparent or translucent and generally colorless. A natural polymer, a synthetic polymer, a copolymer, and other media for forming a film, for example, those described in paragraph “0069” of JP-A No. 2001-330918.

  Among these, preferred binders for the photosensitive layer are polyvinyl acetals, and particularly preferred is polyvinyl butyral. These will be described in detail later.

  For non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters which are polymers with higher softening temperatures, especially polymers such as triacetyl cellulose and cellulose acetate butyrate preferable. In addition, as needed, said binder can be used in combination of 2 or more type.

The binder includes —COOM, —SO ₃ M, —OSO ₃ M, —P═O (OM) ₂ , —O—P═O (OM) ₂ , —N (R) ₂ , —N ⁺ (R) _3. (M represents a hydrogen atom or an alkali metal base, R represents a hydrocarbon group), a group in which at least one polar group selected from an epoxy group, —SH, —CN and the like is introduced by copolymerization or addition reaction It is preferable to use, and —SO ₃ M and —OSO ₃ M are particularly preferable. The amount of such a polar group is 1 × 10 ⁻¹ to 1 × 10 ⁻⁸ mol / g, preferably 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / g.

  Such a binder is used in an effective range to function as a binder.

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

  The glass transition temperature (Tg) of the binder used in the present invention is preferably 70 to 105 ° C. Tg can be obtained by measuring with a differential scanning calorimeter, and the intersection of the baseline and the endothermic peak slope is defined as Tg. Tg in the present invention is determined by the method described in “Polymer Handbook” III-139-179 (1966, Wiley and Sun, Inc.) by Brand Wrap et al.

  Tg when the binder is a copolymer resin is obtained by the following formula.

Tg (copolymer) (° C.) = V ₁ Tg ₁ + v ₂ Tg ₂ +... + V _n Tg _{n
Wherein, v 1, v 2 ··· v} n represents the mass fraction of the monomer in the _{copolymer, Tg 1, Tg 2 ··· Tg} n from each monomer in the copolymer Tg (° C.) of the obtained single polymer is represented. The accuracy of Tg calculated according to the above equation is ± 5 ° C.

  Use of a binder having a Tg of 70 to 105 ° C. is preferable because a sufficient maximum density can be obtained in image formation.

  The binder according to the present invention has a Tg of 70 to 105 ° C., a number average molecular weight of 1,000 to 1,000,000, preferably 10,000 to 500,000, and a degree of polymerization of about 50 to 1,000. Is. Examples of the polymer or copolymer containing an ethylenically unsaturated monomer as a constituent unit include those described in paragraph No. “0069” of JP-A No. 2001-330918.

  Of these, particularly preferred examples include methacrylic acid alkyl esters, methacrylic acid aryl esters, and styrenes. Among such polymer compounds, a polymer compound having an acetal group is preferably used. Even a high molecular compound having an acetal group is more preferably a polyvinyl acetal having an acetoacetal structure, for example, U.S. Pat. Nos. 2,358,836, 3,003,879, 2,828,204, UK The polyvinyl acetal shown by patent 771,155 etc. can be mentioned.

  As the polymer compound having an acetal group, a compound represented by the general formula (V) described in [150] of JP-A No. 2002-287299 is particularly preferable.

As the polyurethane resin that can be used in the present invention, known resins such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane, and polycaprolactone polyurethane can be used. Moreover, it is preferable to have a total of 2 or more hydroxyl groups, at least one at each polyurethane molecule end. Since hydroxyl groups are cross-linked with polyisocyanate which is a curing agent to form a three-dimensional network structure, it is more preferable that the hydroxyl groups are contained in the molecule. In particular, it is preferable that the hydroxyl group is at the molecular end because the reactivity with the curing agent is high. The polyurethane preferably has 3 or more hydroxyl groups at the molecular terminals, and particularly preferably 4 or more. In the present invention, when polyurethane is used, Tg is preferably 70 to 105 ° C., elongation at break is 100 to 2000%, and stress at break is preferably 0.5 to 100 N / mm ² .

  These polymer compounds (polymers) may be used alone or in a blend of two or more.

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

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

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

  Here, the polymer latex is a water-insoluble hydrophobic polymer dispersed as fine particles in a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion is polymerized, the micelle is dispersed, or the polymer molecule has a partially hydrophilic structure, and the molecular chain itself is molecularly dispersed. Any of these may be used. The average particle diameter of the dispersed particles is preferably 1 to 50,000 nm, more preferably in the range of about 5 to 1,000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  The polymer latex that can be used in the silver salt photothermographic dry imaging material of the present invention may be a so-called core / shell type latex in addition to a normal uniform polymer latex. In this case, it may be preferable to change the Tg of the core and the shell. The minimum film-forming temperature (MFT) of the polymer latex according to the present invention is preferably -30 to 90 ° C, more preferably about 0 to 70 ° C. In addition, a film-forming auxiliary may be added to control the minimum film-forming temperature.

  The film-forming aid, also called a plasticizer, is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of polymer latex. For example, “Synthetic Latex Chemistry (Souichi Muroi, published by Polymer Publishing Co., Ltd.) , 1970).

  Examples of the polymer species used for the polymer latex include acrylic resins, vinyl acetate resins, polyester resins, polyurethane resins, rubber resins, vinyl chloride resins, vinylidene chloride resins, polyolefin resins, and copolymers thereof. The polymer may be a linear polymer, a branched polymer, or a crosslinked polymer. The polymer may be a so-called homopolymer in which a single monomer is polymerized or a copolymer in which two or more monomers are polymerized. In the case of a copolymer, it may be a random copolymer or a block copolymer. The molecular weight of the polymer is a number average molecular weight and is usually about 5,000 to 1,000,000, preferably about 10,000 to 100,000. When the molecular weight is too small, the mechanical strength of the photosensitive layer is insufficient, and when the molecular weight is too large, the film forming property is poor and both are not preferable.

  The polymer latex preferably has an equilibrium water content of 0.01 to 2% by mass or less, more preferably 0.01 to 1% by mass at 25 ° C. and 60% RH (relative humidity). For the definition and measurement method of the equilibrium moisture content, for example, “Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Polymer Society, Jinshokan)” can be referred to.

  Specific examples of the polymer latex include each latex described in “0173” of JP-A No. 2002-287299. These polymers may be used alone or in combination of two or more as required. As a polymer seed | species of a polymer latex, what contains about 0.1-10 mass% of carboxylic acid components, such as an acrylate or a methacrylate component, is preferable.

  Furthermore, if necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose or the like may be added within a range of 50% by mass or less of the total binder. The addition amount of these hydrophilic polymers is preferably 30% by mass or less based on the total binder of the photosensitive layer.

  Regarding the order of addition of the organic silver salt and the aqueous dispersed polymer latex in the preparation of the coating solution for the photosensitive layer, any of them may be added first or simultaneously, but preferably the polymer latex is used. Later.

  Furthermore, it is preferable that an organic silver salt and further a reducing agent are mixed before adding the polymer latex. In addition, after mixing the organic silver salt and the polymer latex, if the temperature to be aged is too low, the coated surface shape is impaired, and if it is too high, there is a problem that fog increases, so the coating solution after mixing is 30 to 65 ° C. It is preferable that the above time is elapsed. Furthermore, it is preferable to be aged at 35 to 60 ° C, and a time at 35 to 55 ° C is particularly preferable. In order to maintain the temperature in this way, it is sufficient to keep the temperature of the coating solution preparation tank or the like.

  For coating of the coating solution for the photosensitive layer, it is preferable to use a coating solution that has passed 30 minutes to 24 hours after mixing the organic silver salt and the aqueous polymer latex, and more preferably, 60 minutes after mixing. It is to make -12 hours pass, and it is especially preferable to use the coating liquid which passed 120 minutes-10 hours.

  Here, “after mixing” means after the organic silver salt and the aqueous polymer latex are added and the additive material is uniformly dispersed.

(Crosslinking agent)
The photosensitive layer according to the present invention may contain a cross-linking agent capable of connecting the binders according to the present invention by cross-linking. By using a crosslinking agent for the binder, it is known that filming is improved and development unevenness is reduced, but there is also an effect of suppressing fogging during storage and suppressing generation of printout silver after development. is there.

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

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

  In addition, the adduct of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion and prevent layer peeling, image shift and bubble generation. Such isocyanates may be placed 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) photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer and can be added to one or more of these layers.

  As the thioisocyanate-based crosslinking agent that can be used in the present invention, compounds having a thioisocyanate structure corresponding to the above-mentioned isocyanates are also useful.

  The amount of the crosslinking agent used is usually in the range of 0.001 to 2 mol, preferably 0.005 to 0.5 mol, with respect to 1 mol of silver.

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

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

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

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

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

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

  Although various mechanisms for the function of reducing the required silver amount are conceivable, a compound having a function of improving the covering power of developed silver is preferred. Here, the covering power of developed silver refers to the optical density per unit amount of silver. This silver saving agent can be present in the photosensitive layer, the non-photosensitive layer, or both. Preferred examples of the silver saving agent include hydrazine derivative compounds, vinyl compounds, phenol derivatives, naphthol derivatives, quaternary onium compounds, and silane compounds.

  Specific examples of the hydrazine derivative include compounds H-1 to H-29 described in US Pat. No. 5,545,505, columns 11 to 20, US Pat. No. 5,464,738, columns 9 to 11. 1 to 12 described in JP-A-2001-27790, compounds H-1-1 to H-1-28 described in paragraphs “0042” to “0052”, and H-2-1 to H-2- 9, H-3-1 to H-3-12, H-4-1 to H-4-21, H-5-1 to H-5-5.

  Specific examples of the vinyl compound include compounds CN-01 to CN-13 described in columns 13 to 14 of US Pat. No. 5,545,515 and column 10 of US Pat. No. 5,635,339. Compounds HET-01 to HET-02 described in US Pat. No. 5,654,130, columns MA-10 to compounds MA-01 to MA-07, US Pat. No. 5,705,324 Compounds IS-01 to IS-04 described in columns 9 to 10 of the specification, and compounds 1-1 to 218-2 described in paragraphs “0043” to “0088” of JP-A-2001-125224.

  Specific examples of the phenol derivative and the naphthol derivative include compounds A-1 to A-89 described in paragraphs “0075” to “0078” of JP 2000-267222 A, and paragraph “0025” of JP 2003-66558 A. ”To“ 0045 ”. Examples thereof include compounds A-1 to A-258.

  Specific examples of the quaternary onium compound include triphenyltetrazolium.

  Specific examples of the silane compound include alkoxysilane compounds having two or more primary or secondary amino groups as shown in compounds A1 to A33 described in paragraphs “0027” to “0029” of JP-A No. 2003-5324 or The salt is mentioned.

The amount of the silver saving agent added is in the range of 1 × 10 ⁻⁵ to 1 mol, preferably 1 × 10 ^{−4 to} 5 × 10 ⁻¹ mol, per mol of the organic silver salt.

  Hereafter, the preferable specific example of the silver saving agent of this invention is given. The present invention is not limited to these.

(Thermal solvent)
The silver salt photothermographic dry imaging material of the present invention preferably contains a thermal solvent. Here, the thermal solvent is a material capable of lowering the heat development temperature by 1 ° C. or more compared to the silver salt photothermographic dry imaging material containing no thermal solvent, compared to the silver salt photothermographic dry imaging material containing the thermal solvent. It is defined as More preferably, the material can lower the heat development temperature by 2 ° C. or more, and particularly preferably the material that can lower the temperature by 3 ° C. or more. For example, when the silver salt photothermographic dry imaging material A containing a thermal solvent is B, the silver salt photothermographic dry imaging material A containing no thermal solvent from the silver salt photothermographic dry imaging material A is silver salt photothermographic dry. The heat development temperature for obtaining the density obtained by exposing the imaging material B to the heat development temperature of 120 ° C. and the heat development time of 20 seconds with the silver salt photothermographic dry imaging material A with the same exposure amount and heat development time is The case where it becomes 119 degrees C or less is made into a thermal solvent.

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

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

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

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

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

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

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

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

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

(Anti-fogging and image stabilizer)
In any constituent layer of the silver salt photothermographic dry imaging material of the present invention, an antifoggant for preventing fogging during storage before heat development, and an image deterioration after heat development are prevented. It is preferable to contain an image stabilizer.

  The antifogging and image stabilizer that can be used in the silver salt photothermographic dry imaging material of the present invention will be described.

As reducing agents according to the present invention, reducing agents having protons such as bisphenols and sulfonamidophenols are mainly used, so that these hydrogens are stabilized, the reducing agents are deactivated, and silver ions are reduced. It is preferable that a compound capable of preventing and preventing the reaction is contained. Further, it is preferable that a raw silver salt photothermographic dry imaging material or a compound capable of oxidatively bleaching silver atoms or metallic silver (silver clusters) generated during image storage is contained. Specific examples of compounds having these functions include biimidazolyl compounds and iodonium compounds. The amount of the biimidazolyl compound and iodonium compound added is in the range of 0.001 to 0.1 mol / m ² , preferably 0.005 to 0.05 mol / m ² .

  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 is used. It is preferable to use together. Specific examples of particularly preferred hydrogen bonding compounds in the present invention include, for example, compounds (II-1) to (II-40) described in paragraphs [0061] to [0064] of JP-A-2002-90937. Is mentioned.

  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 JP-A-2002-287299, [0264] to [0271].

  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 released from the compound and silver ions does not become a problem. Specific examples of the compound that generates these active halogen atoms include, in addition to the above-mentioned publications, compounds (III-1) to 3 described in paragraphs “0086” to “0087” of JP-A No. 2002-169249. (III-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 paragraphs “0050” to “0056” Compounds 2a to 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, paragraphs “0069” to Examples thereof include compounds 5-1 to 5-10 described in “0072”.

  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 paragraph “0028” of JP-A-7-209797. Thiosulfonate esters A to K, compound examples (1) to (44) described from p14 of JP-A No. 55-140833, compounds described in paragraph “0063” of JP-A No. 2001-13627 (I-1 ) To (I-6), (C-1) to (C-3) described in paragraph “0066”, and compounds (III-1) to (III-) described in paragraph “0027” of JP-A-2002-90937. 108), compounds VS-1 to VS-7 and compounds HS-1 to HS-5 described in paragraph “0013” of JP-A-6-208192 as compounds of vinyl sulfones and / or β-halo sulfones. KS-1 to KS-8 compounds described in JP 2000-330235 A as sulfonylbenzotriazole compounds, PR-01 to PR-08 described in JP-T 2000-515995 as substituted propene nitrile compounds, Examples thereof include compounds (1) -1 to (1) -132 described in paragraphs “0042” to “0051” of JP-A-2002-207273.

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

  In addition to the above compounds, the silver salt photothermographic dry imaging material of the present invention may contain various compounds conventionally known as antifoggants, but the same reaction activity as the above compounds. Even if it is a compound which can produce | generate a seed | species, the compound from which an antifogging mechanism differs may be sufficient. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. No. 3,874,946. Examples thereof include compounds described in the specification, JP 4,756,999, JP-A-9-288328, and JP-A-9-90550. Further, as other antifoggants, compounds disclosed in US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981 and 631,176 are exemplified. Can be mentioned.

(Toning agent)
The silver salt photothermographic dry imaging material of the present invention forms a photographic image by heat development processing, and a toning agent (toner) for adjusting the color tone of silver as required is usually contained in an (organic) binder matrix. It is preferably contained in a dispersed state.

  Examples of suitable toning agents used in the present invention include Research Disclosure (RD) 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, and the like. For example, the following are disclosed.

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

(Fluorosurfactant)
In the present invention, fluorine represented by the following general formula (SF) is used to improve the transportability and environmental suitability (accumulation in vivo) of silver salt photothermographic dry imaging materials in a laser imager (thermal development processing apparatus). A system surfactant is preferably used.

General formula (SF)
(R _f − (L ₁ ) _n1 −) _p − (Y) _m1 − (A) _q
[Wherein R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, n1 and m1 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, n1 and m1 are not 0 at the same time. ]
In the general formula (SF), R _f represents a substituent containing a fluorine atom. Examples of the substituent containing the fluorine atom include a fluorinated alkyl group having 1 to 25 carbon atoms (for example, trifluoromethyl). Group, trifluoroethyl group, perfluoroethyl group, perfluorobutyl group, perfluorooctyl group, perfluorododecyl group and perfluorooctadecyl group) or fluorinated alkenyl group (for example, perfluoropropenyl group, perfluorobutenyl group) Perfluorononenyl group, perfluorododecenyl group, etc.). R _f preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. R _f preferably has 2 to 12 fluorine atoms, more preferably 3 to 12 fluorine atoms.

L ₁ represents a divalent linking group having no fluorine atom. Examples of the divalent linking group having no fluorine atom include an alkylene group (for example, a methylene group, an ethylene group, a butylene group, etc.), Alkyleneoxy group (methyleneoxy group, ethyleneoxy group, butyleneoxy group, etc.), oxyalkylene group (for example, oxymethylene group, oxyethylene group, oxybutylene group, etc.), oxyalkyleneoxy group (for example, oxymethyleneoxy group, Oxyethyleneoxy group, oxyethyleneoxyethyleneoxy group, etc.), phenylene group, oxyphenylene group, phenyloxy group, oxyphenyloxy group, or a combination of these groups.

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

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

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

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

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

  Specific examples of the above-described fluorosurfactants include compounds (FS-1) to (FS-66) described in paragraphs “0029” to “0040” of JP-A No. 2003-149766, JP-A No. 2004-021084. Compound 1-1 to 1-4 described in paragraph “0014” of compound No., compounds 2-1 to 2-10 described in paragraph “0019”, and paragraph “0025” of Japanese Patent Application Laid-Open No. 2004-077772. Examples thereof include compounds described in paragraph “0030”.

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

  Further, as fluorine surfactants other than those described above, compounds described in paragraph “0035” of JP-A No. 2004-117505, JP-A No. 2000-214554, JP-A No. 2003-156819, JP-A No. 2003-177494 are disclosed. The compounds described in JP-A No. 2003-114504, JP-A 2003-270754, and JP-A 2003-270760 may be used. In the present invention, it is particularly preferable to use a combination of an anionic fluorine-containing surfactant represented by the general formula (SF) and a known nonionic fluorine-containing surfactant from the viewpoint of improving charging characteristics and coating properties.

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

The amount of the fluorosurfactant represented by the general formula (SF) 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, the charging characteristics may not be obtained. If the range exceeds the former range, the humidity dependency is large and the storage stability under high humidity may be deteriorated.

(lubricant)
As the lubricant, for example, known lubricants described in paragraphs “0061” to “0064” of JP-A No. 11-84573 can be used. However, solid lubricant particles or a lubricant that is liquid at room temperature is used. It is preferable. Examples of the lubricant that is liquid at room temperature include compounds described in paragraph “0019” of JP-A No. 2003-15259. As the solid lubricant particles, organic solid lubricant particles having an average particle diameter of 1 to 30 μm are preferably used, and the melting point of the organic solid lubricant particles is preferably 110 ° C. or higher and 200 ° C. or lower. Examples of the organic solid lubricant particles include compounds described in paragraph “0036” of JP-A-2006-003702.

(Layer containing radiation absorbing compound)
The silver salt photothermographic dry imaging material of the present invention is provided on the side opposite to the side where the photosensitive layer is provided across the support and the layer on the side where the photosensitive layer is provided on the support. Various known dyes and pigments can be used as the radiation absorbing compound used in the layer. Any of these dyes and pigments may be used. For example, there are pigments and dyes described in the color index, specifically pyrazoloazole dyes, anthraquinone dyes, azo dyes, azomethine dyes, oxonol dyes, carbocyanine dyes, styryl dyes. , Triphenylmethane dyes, indoaniline dyes, indophenol dyes, organic pigments such as phthalocyanine, and inorganic pigments.

Preferred dyes used in the present invention include anthraquinone dyes (for example, compounds 1 to 9 described in JP-A-5-341441, compounds 3-6 to 18 and 3-23 to 38 described in JP-A-5-165147), azomethine Dyes (compounds 17 to 47 described in JP-A-5-341441), indoaniline dyes (for example, compounds 11 to 19 described in JP-A-5-289227, compound 47 described in JP-A-5-341441, And compounds 2-10 to 11 described in JP-A No. 165147) and azo dyes (compounds 10 to 16 described in JP-A-5-341441). For example, when the silver salt photothermographic dry imaging material of the present invention is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus and a pyrylium nucleus as disclosed in JP-A-2001-83655 are used. It is preferable to use a squarylium dye having a thiopyrylium croconium dye or a pyrylium croconium dye similar to the squarylium dye. The compound having a squarylium nucleus is a compound having 1-cyclobutene-2-hydroxy-4-one in the molecular structure, and the compound having a croconium nucleus is 1-cyclopentene-2-hydroxy- in the molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Examples of the dye include compounds described in JP-A-8-201959, compounds described in JP-T-9-509503, and compounds AD-1 to AD-55 described in JP-A-2003-195450. Is also preferable. When the silver salt photothermographic dry imaging material of the present invention is used as an image recording material by blue light, the compound No. described in JP-A-2003-215751 is used. 1-No. 93, and Dye-1 to Dye-51 described in JP-A-2005-157245 are preferably used. Further, these dyes may be added by any method such as a solution, an emulsion, a solid fine particle dispersion, or a mordanted state in a polymer mordant. The amount of these compounds to be used is determined by the target absorption amount, but generally it is preferably used in the range of 1 μg to 1 g per 1 m ^{2 of the} light-sensitive material. In the silver salt photothermographic dry imaging material of the present invention, the layer on the side of the support on which the photosensitive layer is provided, specifically the undercoat layer, the photosensitive layer, the intermediate layer, and the protective layer, more preferably photosensitive. The radiation-absorbing compound (dye or pigment) is contained in the active layer, the absorbance at the exposure wavelength in all layers of these layers is set to 0.30 to 1.00, and the support is sandwiched. A radiation-absorbing compound (dye or pigment) in the layer opposite to the side where the photosensitive layer is provided, specifically in the antistatic undercoat layer, antihalation layer, protective layer, more preferably in the antihalation layer It is preferable to set the absorbance at the exposure wavelength in all layers of these layers in the range of 0.20 to 1.50. Further, the absorbance at the exposure wavelength in the total layer of the layers on the side on which the photosensitive layer is provided on the support is preferably 0.40 to 0.90, particularly preferably 0.50 to 0.80. It is. Further, the absorbance at the exposure wavelength of the total layer of the layers provided on the side opposite to the side where the photosensitive layer is provided across the support is preferably 0.30 to 1.20, more preferably Preferably it is 0.40-1.00. By setting it within this range, even when a resin lens is used in the exposure system, it is possible to greatly improve the density fluctuation accompanying the image product room and humidity change.

(Surface layer)
The ten-point average roughness (Rz), maximum roughness (Rt), and centerline average roughness (Ra) in the present invention are defined by the following JIS surface roughness (B0601). Ten-point average roughness (Rz) is the peak from the highest to the fifth measured in the direction of the vertical magnification from the straight line that is parallel to the average line and does not cross the cross-sectional curve, in the portion that has been cut by the reference length from the cross-sectional curve. The difference between the average value of the altitude and the average value of the altitude at the bottom of the valley from the deepest to the fifth is expressed in micrometers (μm). The maximum roughness (Rt) is the roughness curve extracted by the reference length L, and when the extracted part is sandwiched between two straight lines parallel to the center line, the distance between the two straight lines is measured in the direction of the vertical magnification of the roughness curve. Then, this value is expressed in micrometers (μm). The centerline average roughness (Ra) is a portion of the measured length L extracted from the roughness curve in the direction of the centerline, the centerline of this extracted portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve Is represented by y = f (x), the value obtained by the following equation is expressed in micrometers (μm).

  As a method for measuring Rz, Rt, and Ra, the humidity was adjusted for 24 hours under the condition that the measurement samples were not overlapped in an environment of 25 ° C. and 65% RH, and then measured in the environment. The non-overlapping conditions shown here include, for example, a method in which the edge of the silver salt photothermographic dry imaging material is rolled up or a paper is placed between the silver salt photothermographic dry imaging material and the silver salt photothermographic dry imaging material. It is either a method of stacking with three or a method of making a frame with cardboard and fixing its four corners. Examples of the measuring apparatus that can be used include a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO.

  The Rz, Rt, and Ra on the front and back surfaces of the silver salt photothermographic dry imaging material can be easily adjusted by appropriately combining the following technical means.

1) Type of matting agent (inorganic or organic powder) contained in the layer on the side having the photosensitive layer and the layer opposite to the side having the photosensitive layer, the average particle diameter, the amount added, and the surface treatment method 2) Matting agent Dispersion conditions (type of disperser used, dispersion time, type of beads used for dispersion, average particle size, type and amount of dispersant used during dispersion, type of polar group of binder, polar group content)
3) Drying conditions at the time of application (application speed, distance from the application surface of the hot air blowing nozzle, amount of dry air), amount of residual solvent 4) Type of filter used for filtering the coating liquid, filtration time 5) Calendar treatment after application Conditions (for example, calendar temperature 40-80 ° C, pressure 50-300 kg / cm, line speed 20-100 m / min, nip number 2-6)
In the present invention, the value of Rz (E) / Rz (B) is preferably 0.1 or more and 0.7 or less, and particularly the value of Rz (E) / Rz (B) is 0.2 or more, It is preferably 0.6 or less, more preferably 0.3 or more and 0.55 or less. Here, (E) represents the outermost surface on the photosensitive layer side, and (B) represents the outermost surface on the back coat layer side opposite to the photosensitive layer. By setting this range, the transportability of the silver salt photothermographic dry imaging material is good, and the occurrence of density unevenness during thermal development can be remarkably improved.

  In the present invention, the value of Ra (E) / Ra (B) is preferably 0.6 or more and 1.5 or less, and particularly the value of Ra (E) / Ra (B) is 0.6 or more. 1.3 or less, more preferably 0.7 or more and 1.1 or less. By setting it within this range, the fog rise with time is small, the transportability of the silver salt photothermographic dry imaging material is good, and the occurrence of uneven density during thermal development can be further improved.

  The silver salt photothermographic dry imaging material of the present invention preferably has constituent layers containing a plurality of types of matting agents on both sides on the support from the viewpoint of improving the image quality of the image. The average particle diameter of the matting agent having the maximum average particle diameter of the matting agent contained in the layer containing the matting agent on the side having the photosensitive layer is Le (μm), opposite to the side having the photosensitive layer across the support. When the average particle diameter of the matting agent having the maximum average particle diameter of the matting agent contained in the layer containing the matting agent on the side, that is, the side having the back coat layer is Lb (μm), Lb / Le is 2.0 to It is preferable that it is 10, More preferably, it is 3.0-4.5.

  By setting Lb / Le within this range, density unevenness during heat development can be improved. In the image forming method of the present invention, the value of Rz (E) / Ra (E) is preferably 12 or more and 60 or less, more preferably 14 or more and 50 or less. By setting the value of Rz (E) / Ra (E) within this range, density unevenness during thermal development and storage characteristics over time can be improved.

  In the image forming method of the present invention, the value of Rz (B) / Ra (B) is preferably 25 or more and 65 or less, more preferably 30 or more and 60 or less. By setting the value of Rz (B) / Ra (B) within this range, density unevenness during heat development and storage characteristics over time can be improved. About the above-mentioned surface roughness, it carried out with the following method.

<< Evaluation of surface roughness >>
About the sample before the process of heat development, it measured by the method shown below using the non-contact three-dimensional surface analyzer (WYKO company RST / PLUS).

1) Objective lens: × 10.0 Intermediate lens: × 1.0
2) Measurement range: 463.4 μm × 623.9 μm
3) Pixel size: 368 × 238
4) Filter: Cylindrical correction and tilt correction 5) Smoothing: Medium smoothing 6) Scanning speed: Low
Ra, Rz, and Rt were defined according to JIS surface roughness (B0601). For each sample of 10 cm × 10 cm, the sample was divided into 100 in a grid pattern at 1 cm intervals, the center of each square region was measured, and the average value was obtained from 100 measurements.

  In the present invention, the case where the layer containing the matting agent is the outermost layer is one of the preferred embodiments. That is, even when a non-photosensitive layer is provided on the opposite side of the photosensitive layer of the silver salt photothermographic dry imaging material of the present invention, the surface roughness is controlled as the outermost layer. For this purpose, it is preferable to use organic or inorganic powder as a matting agent.

As the powder used in the present invention, a powder having a Mohs hardness of 5 or more is preferably used. As the powder, a known inorganic powder or organic powder can be appropriately selected and used. Examples of the inorganic powder include titanium oxide, boron nitride, SnO ₂ , SiO ₂ , Cr ₂ O ₃ , α-Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, SiC, cerium oxide, corundum, artificial Examples thereof include diamond, garnet, garnet, mica, silica, silicon nitride, silicon carbide and the like. Examples of the organic powder include powders such as polymethyl methacrylate, polystyrene, and Teflon (registered trademark). Among these, inorganic powders such as SiO ₂ , titanium oxide, barium sulfate, α-Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, Cr ₂ O ₃ , mica, etc. are preferable. SiO ₂ and α-Al ₂ O ₃ are preferable, and SiO ₂ is particularly preferable.

In the present invention, the powder is preferably surface-treated, for example. The surface treatment layer is formed by dry pulverizing the inorganic powder material, adding water and a dispersing agent, and performing coarse particle classification by wet pulverization and centrifugal separation. Thereafter, the fine slurry is transferred to a surface treatment tank, where the surface of the metal hydroxide is coated. First, a predetermined amount of an aqueous salt solution such as Al, Si, Ti, Zr, Sb, Sn, and Zn is added, and an acid or alkali that neutralizes the solution is added, and the surface of the inorganic powder particles is coated with the resulting hydrous oxide. To do. Water-soluble salts produced as a by-product are removed by decantation, filtration, and washing. Finally, the slurry pH is adjusted, filtered, and washed with pure water. The washed cake is dried with a spray dryer or a band dryer. Finally, the dried product is pulverized by a jet mill to become a product. In addition to the aqueous system, AlCl ₃ and SiCl ₄ vapors can be passed through the non-magnetic inorganic powder, and then steam can be introduced to perform Al and Si surface treatment. For other surface treatment methods, “Characterization of Powder Surfaces”, Academic Press can be referred to.

  In the present invention, it is preferable that the surface treatment is performed with an Si compound or an Al compound. When such a surface-treated powder is used, the dispersion state when the matting agent is dispersed can be improved. The content of Si or Al is preferably 0.1 to 10% by mass of Si and 0.1 to 10% by mass of Al, more preferably 0.1 to 10% by mass with respect to the powder. It is particularly preferable that 5% by mass, Al is 0.1-5% by mass, Si is 0.1-2% by mass, and Al is 0.1-2% by mass. The mass ratio of Si and Al is preferably Si <Al. The surface treatment can be performed by the method described in JP-A-2-83219. The average particle diameter of the powder in the present invention is the average diameter in the case of spherical powder, the average major axis length in the case of acicular powder, and the maximum diagonal length of the plate-like surface in the case of plate-like powder. Mean values can be easily obtained from measurement with an electron microscope.

  The organic or inorganic powder preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm.

  The average particle diameter of the organic or inorganic powder contained in the outermost layer on the photosensitive layer side is usually 0.5 to 8.0 μm, preferably 1.0 to 6.0 μm, more preferably 2.0 to 5.0 μm. It is.

  The addition amount is usually 1.0 to 20% by mass, preferably 2.0 to 15% by mass, more preferably 3 with respect to the amount of binder used in the outermost layer (including the crosslinking agent in the binder amount). 0.0 to 10% by mass.

  The average particle size of the organic or inorganic powder contained in the outermost layer opposite to the photosensitive layer side across the support is usually 2.0 to 15.0 μm, preferably 3.0 to 12.0 μm. More preferably, it is 4.0-10.0 micrometers. The addition amount is usually 0.2 to 10% by mass, preferably 0.4 to 7% by mass, and more preferably 0 to the amount of binder used in the outermost layer (including the crosslinking agent in the binder amount). .6 to 5% by mass.

  The variation coefficient of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

{(Standard deviation of particle size) / (Average value of particle size)} × 100
The method of adding the organic or inorganic powder may be a method in which the organic or inorganic powder is previously dispersed in the coating solution, or a method of spraying the organic or inorganic powder after the coating solution is applied and before the drying is completed. May be. Moreover, when adding several types of powder, you may use both methods together.

(Support)
Examples of the support material used in the silver salt photothermographic dry imaging material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (aluminum, etc.), etc. For handling, a material that can be processed into a flexible sheet or roll is preferable. Therefore, as a support in the 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 layer or the surface protective layer on the photosensitive layer side, the undercoat layer and the like. The conductive compounds described in columns 14 to 20 of US Pat. No. 5,244,773 are preferably used. Among these, in the present invention, the surface protective layer on the backing layer side preferably contains a conductive metal oxide. This proved that the effects of the present invention (particularly the transportability during heat development) can be further enhanced.

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

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

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

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

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

  For gradation adjustment or the like, two or more photosensitive layers may be provided on one side of the support or one or more layers on both sides of the support.

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

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

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

In the present invention, the silver coating amount is preferably selected in accordance with the purpose of the silver salt photothermographic dry imaging material, but is 0.3 g / m ² or more for medical purposes. .5g / m ² or less are preferred, 0.5 g / m ² or more, more preferably 1.4 g / m ² or less, 0.7 g / m ² or more, 1.2 g / m ² or less is particularly preferred. Among the applied silver amounts, those derived from silver halide preferably account for 2 to 18%, more preferably 5 to 15%, based on the total silver amount.

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

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

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

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

  The content of the solvent in the silver salt photothermographic dry imaging 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.

(Packaging body)
When storing the silver salt photothermographic dry imaging material of the present invention, oxygen transmission rate and / or water transmission rate are used to prevent density change and fog generation over time, or to improve curling, curling, etc. It is preferable to package with a low packaging material. The oxygen permeability is preferably 50 ml / atm · m ² · day or less at 25 ° C. (where 1 atm is 1.01325 × 10 ⁵ Pa), more preferably 10 ml / atm · m ² · day or less, More preferably, it is 1.0 ml / atm · m ² · day or less. The moisture permeability is preferably 0.01 g / m ² · 40 ° C · 90% RH · day or less (according to JIS Z0208 cup method), more preferably 0.005 g / m ² · 40 ° C. · 90% RH · Day or less, more preferably 0.001 g / m ² · 40 ° C · 90% RH · day or less.

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

  Further, in the cutting process and the packaging process, in order to prevent image defects such as scratches and white spots, the cleanliness is US federal standard 209d class 10,000 or less as disclosed in, for example, JP-A-2004-341145. It is preferable to perform the work in the environment of

(Overall configuration of the device)
The laser imager (thermal development processing apparatus) according to the present invention is uniform and stable on the entire surface of a sheet photosensitive material supply unit represented by a sheet photosensitive material 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 sheet photosensitive material supplying unit to the outside of the apparatus.

  In the laser imager preferably used in the present invention, the ratio of the path length of the cooling section to the path length of the heat developing section is 1.5 or less, more preferably 0.1 or more and 1.2 or less. It is especially preferable that it is 2 or more and 1.0 or less. Here, the path length of the thermal development section is a transport path length in which the silver salt photothermographic dry imaging material is heated to the development temperature in the thermal development apparatus. The path length of the cooling unit is defined as the silver salt photothermographic drying unit from the area where the silver salt photothermographic dry imaging material is shielded by the laser imager to the room light where the laser imager is installed. The path length until the imaging material is discharged.

  In addition, the laser imager has a photosensitive layer with a cooling rate on the surface (hereinafter referred to as “non-photosensitive surface”) that does not have a photosensitive layer across the support of the silver salt photothermographic dry imaging material. It is preferable to have a function that can be set higher than the cooling rate of the side surface (hereinafter referred to as “photosensitive surface”).

  In the present invention, the ratio of the cooling rate of the non-photosensitive surface to the cooling rate of the photosensitive surface is preferably 1.1 or more. More preferably, it is 1.1-5.0, Most preferably, it is 1.5-3.0. The means for increasing the cooling rate of the non-photosensitive surface is not particularly limited, but it is a preferred embodiment that the non-photosensitive surface is directly brought into contact with a metal plate, a metal roller, a non-woven fabric, or a flocked roller. More preferably, it is also desirable to use a heat sink or a heat pipe together in order to positively discharge the heat accumulated in these members to the outside.

  It is possible to provide a small-sized laser imager with a high processing speed by using a laser imager with a short path length of the cooling unit whose ratio of the path length of the cooling unit to the path length of the heat developing unit is 1.5 or less. .

  The cooling time from the exit from the heat development portion to the discharge is arbitrary, but it is preferably from 0 second to 25 seconds. More preferably, it is 0 second or more and 15 seconds or less, and particularly preferably 5 seconds or more and 15 seconds or less.

  The path length through which the silver salt photothermographic dry imaging material passes after exiting the heat developing portion and before discharging is arbitrary, but is preferably 1 cm or more and 60 cm or less. More preferably, they are 5 cm or more and 50 cm or less, More preferably, they are 5 cm or more and 40 cm or less.

  The silver salt photothermographic dry imaging material of the present invention may be developed by any method. Usually, the silver salt photothermographic dry imaging material exposed imagewise is heated and developed. The preferred development temperature is 80 to 250 ° C, preferably 100 to 140 ° C, more preferably 110 to 130 ° C. The development time is preferably 1 to 10 seconds, more preferably 2 to 10 seconds, and further preferably 3 to 10 seconds. If the heating temperature is less than 80 ° C., sufficient image density cannot be obtained in a short time. If the heating temperature exceeds 200 ° C., the binder melts, and not only the image itself such as transfer to a roller but also transportability and developing machine etc. Adversely affect. By heating, a silver image is generated by an oxidation-reduction reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside. The time required for the heat development processing (the time taken for the silver salt photothermographic dry imaging material to be picked up after being picked up at the tray portion and discharged) is preferably 60 seconds or less, and 10 seconds or more and 50 seconds or less. Is more preferable because it can cope with an emergency diagnosis.

  Either a drum type heater or a plate type heater may be used as the thermal development method, but the plate heater method is more preferable. As a heat development method using a plate heater method, a method described in JP-A-11-133572, that is, a silver salt photothermographic dry imaging material in which a latent image is formed on silver halide grains by exposure is heated in a heat developing unit. A laser imager that obtains a visible image by contacting the heating means, wherein the heating means comprises a plate heater, and a plurality of pressing rollers are arranged to face each other along one surface of the plate heater, A developing method using a laser imager is preferable, in which the silver salt photothermographic dry imaging material is passed between a pressing roller and the plate heater to perform thermal development.

  The linear velocity of the silver salt photothermographic dry imaging material in the exposure part, the heat development part and the cooling part is arbitrary, but higher speed is preferable for quick processing and improvement of throughput. The linear velocity is preferably 30 mm / second to 200 mm / second, more preferably 30 mm / second to 150 mm, and still more preferably 30 mm / second to 60 mm / second. By setting the conveyance speed within this range, density unevenness during heat development can be improved and the processing time can be shortened.

  FIG. 1 is a side view schematically showing a main part of a heat development apparatus according to a preferred embodiment.

  In order to perform the exposure process and the thermal development process simultaneously, that is, in order to start development on a part of the sheet photosensitive material that has already been exposed while exposing a part of the sheet photosensitive material, the exposure unit that performs the exposure process and development It is preferable that the distance between the portions is 0 cm or more and 50 cm or less, and this makes a series of processing time for exposure and development extremely short. A preferable range of this distance is 3 cm or more and 40 cm or less, and more preferably 5 cm or more and 30 cm or less. Here, the exposure part refers to the position where the light from the exposure light source is irradiated onto the silver salt photothermographic dry imaging material, and the development part is the first time that the silver salt photothermographic dry imaging material is heated for thermal development. Refers to the position. In FIG. 1, the place where the laser beam indicated by L hits the silver salt photothermographic dry imaging material (the tip of the arrow) is the exposure unit, and the silver salt photothermographic dry imaging material conveyed from 45 in FIG. The first contact with the plate is the developing section.

  As a device, apparatus or means for heating, for example, a heating means typical as a heat generator using a hot plate, iron, hot roller, carbon, white titanium or the like may be used. More preferably, the silver salt photothermographic dry imaging material in which the protective layer is provided on the photosensitive layer is subjected to heat treatment by bringing the surface having the protective layer into contact with the heating means, in order to perform uniform heating. In addition, it is preferable from the viewpoint of thermal efficiency, workability, etc., and it is preferable that the surface on the side having the protective layer is conveyed while being in contact with the heat roller, and is developed by heat treatment.

  In the present invention, an image obtained by heat development at a heating temperature of 123 ° C. and a development time of 10 seconds is shown on orthogonal coordinates where the unit lengths of the diffusion density (Y axis) and the common logarithmic exposure (X axis) are equal. In the characteristic curve, the average gradation of 0.25 to 2.5 in terms of optical density with diffused light is preferably 1.8 to 6.0, more preferably 2.0 to 5.0, It is especially preferable that it is 2.0-4.5. By using such gradations, it is possible to obtain an image with high diagnostic recognizability even if the amount of silver is small.

  In order to effectively adapt to the laser imager according to the present invention, the photosensitive layer and the non-photosensitive layer provided on at least one surface of the support of the silver salt photothermographic dry imaging material according to the present invention. The total dry film thickness is preferably 12 μm or more and 19 μm or less, and particularly preferably 14 μm or more and 18 μm or less. The dry film thickness of the photosensitive layer is preferably 4 μm or more and 16 μm or less, more preferably 6 μm or more and 14 μm or less, and particularly preferably 8 μm or more and 12 μm or less.

  As shown in FIG. 1, a thermal development apparatus 40 according to a preferred embodiment includes a photosensitive surface (hereinafter referred to as EC surface) in which a silver salt photothermographic dry imaging material is coated on one surface of a sheet-like support base made of PET or the like. The sheet photosensitive material F having the non-photosensitive surface (hereinafter referred to as BC surface) on the side of the supporting substrate opposite to the EC surface is sub-scanned and conveyed with the laser light L from the optical scanning exposure unit 55 (content description omitted). A latent image is formed on the surface, and then the sheet photosensitive material F is heated and developed from the BC surface side to visualize the latent image, and is conveyed and discharged above the apparatus through a curved conveyance path.

  1 is provided in the vicinity of the bottom of the apparatus housing 40a and accommodates a large number of unused sheet photosensitive materials F, and the uppermost sheet of the sheet photosensitive material storage 45. A pickup roller 46 that picks up and conveys the photosensitive material F, a conveyance roller pair 47 that conveys the sheet photosensitive material F from the pickup roller 46, and the sheet photosensitive material F from the conveyance roller pair 47 is guided and the conveyance direction is almost reversed. A curved guide 48 configured to be curved and conveyed, a pair of conveying rollers 49a and 49b for conveying the sheet photosensitive material F from the curved guide 48 in a sub-scanning manner, and a pair of conveying rollers 49a and 49b. The optical scanning exposure unit 55 for forming a latent image on the EC surface by optically scanning and exposing the sheet photosensitive material F with the laser beam L based on the image data; Provided.

  The thermal development device 40 further heats the sheet photosensitive material F on which the latent image is formed from the BC surface side to raise the temperature to a predetermined thermal development temperature, and heats the heated sheet photosensitive material F Then, a heat retaining part 53 for keeping the temperature at a predetermined heat development temperature, a cooling part 54 for cooling the heated sheet photosensitive material F from the BC surface side, and a density of the sheet photosensitive material F disposed on the outlet side of the cooling part 54 Of the apparatus housing 40a so that the sheet photosensitive material F discharged by the conveying roller pair 57 is placed thereon. And a sheet photosensitive material placing portion 58 provided on the upper surface in an inclined manner.

  As shown in FIG. 1, in the thermal development device 40, the sheet photosensitive material storage unit 45, the substrate unit 59, the conveyance roller pairs 49 a and 49 b, the temperature raising unit 50, and the heat retaining unit 53 are directed upward from the bottom of the apparatus housing 40 a. (Upstream side) are arranged in this order, the sheet photosensitive material storage unit 45 is at the lowermost position, and the substrate unit 59 is provided between the temperature raising unit 50 and the heat retaining unit 53, so that it is hardly affected by heat. Yes.

  Further, since the conveyance path from the pair of conveyance rollers 49a and 49b for the sub-scan conveyance to the temperature raising unit 50 is configured to be relatively short, the sheet photosensitive material F is exposed while the light scanning exposure unit 55 exposes the sheet photosensitive material F. On the front end side of the material F, heat development heating is performed by the temperature raising unit 50 and the heat retaining unit 53.

  The temperature raising unit 50 and the heat retaining unit 53 constitute a heating unit, and the sheet photosensitive material F is heated to the heat development temperature and held at the heat development temperature. The temperature raising unit 50 includes a first heating zone 51 that heats the sheet photosensitive material F on the upstream side, and a second heating zone 52 that heats the sheet photosensitive material F on the downstream side.

  The first heating zone 51 includes a planar heating guide 51b made of a metal material such as aluminum and fixed, a planar heating heater 51c made of a silicon rubber heater or the like in close contact with the back surface of the heating guide 51b, A plurality of opposing surfaces made of silicon rubber or the like, which is arranged on the fixed guide surface 51d of the guide 51b so as to be able to press the sheet photosensitive material so as to maintain a gap narrower than the thickness of the sheet photosensitive material and whose surface is more thermally insulating than metal or the like. And a roller 51a.

  The second heating zone 52 includes a planar heating guide 52b made of a metal material such as aluminum and fixed, a planar heating heater 52c made of a silicon rubber heater or the like in close contact with the back surface of the heating guide 52b, A plurality of opposing surfaces made of silicon rubber or the like, which is disposed on the fixed guide surface 52d of the guide 52b so as to be able to press the sheet photosensitive material so as to maintain a gap narrower than the thickness of the sheet photosensitive material and whose surface is more thermally insulating than metal or the like. And a roller 52a.

  The heat retaining section 53 is configured on a heating guide 53b made of a metal material such as aluminum and fixed, a planar heating heater 53c made of a silicon rubber heater or the like in close contact with the back surface of the heating guide 53b, and a surface of the heating guide 53b. And a guide part 53a made of a heat insulating material or the like disposed so as to face the fixed guide surface 53d so as to have a predetermined gap (slit) d. The heat retaining unit 53 is configured in a planar manner on the temperature raising unit 50 side continuously with the second heating zone 52, and is configured in a curved surface with a predetermined curvature from the middle toward the upper part of the apparatus.

  In the first heating zone 51 of the temperature raising unit 50, the fixed guide surface 51d is provided by the opposing rollers 51a to which the sheet photosensitive material F conveyed by the conveying roller pairs 49a and 49b from the upstream side of the temperature raising unit 50 is rotationally driven. When pressed, the BC surface comes into close contact with the fixed guide surface 51d and is conveyed while being heated.

  Similarly, in the second heating zone 52, the sheet photosensitive material F conveyed from the first heating zone 51 is pressed against the fixed guide surface 52d by each counter roller 52a that is rotationally driven, whereby the BC surface is fixed. It is conveyed while being heated in close contact with the surface 51d.

  Note that a concave portion opened in a V shape may be provided between the second heating zone 52 and the heat retaining portion 53 of the temperature raising unit 50, and foreign matter from the temperature raising unit 50 may be contained in the concave portion. It is possible to prevent foreign matter from the temperature raising unit 50 from being brought into the heat retaining unit 53 by dropping into the heat retaining unit 53.

  In the heat retaining unit 53, the sheet photosensitive material F conveyed from the second heating zone 52 is heated by the heat from the heating guide 53b in the gap d between the fixed guide surface 53d of the heating guide 53b and the guide unit 53a (heat retaining). ) Is passed through the gap d by the conveying force of the counter roller 52a on the second heating zone 52 side. At this time, the sheet photosensitive material F is conveyed while gradually changing the direction from the horizontal direction to the vertical direction in the gap d, and heads toward the cooling unit 54.

  In the cooling unit 54, the sheet photosensitive material F conveyed from the heat retaining unit 53 in the substantially vertical direction is brought into contact with the cooling guide surface 54c of the cooling plate 54b made of a metal material by the counter roller 54a and cooled from the vertical direction. The direction of the sheet photosensitive material F is gradually changed to the sheet photosensitive material placement portion 58 and conveyed in an oblique direction. The cooling effect can be increased by making the cooling plate 54b a finned heat sink structure. A part of the cooling plate 54b may have a heat sink structure with fins.

  The cooled sheet photosensitive material F coming out of the cooling unit 54 is subjected to density measurement by a densitometer 56, conveyed by a conveying roller pair 57, and discharged to a sheet photosensitive material placing unit 58. The sheet photosensitive material placing section 58 can temporarily place a plurality of sheet photosensitive materials F.

  As described above, in the thermal development apparatus 40 of FIG. 1, the sheet photosensitive material F has the BC surface facing the heated fixed guide surfaces 51d, 52d, and 53d in the heating unit 50 and the heat retaining unit 53, and the silver salt The EC surface on which the photothermographic dry imaging material is applied is conveyed in an open state. In the cooling unit 54, the sheet photosensitive material F is conveyed with the BC surface contacting the cooling guide surface 54c and cooled, and the EC surface coated with the silver salt photothermographic dry imaging material is opened.

  Further, the sheet photosensitive material F is conveyed by the opposing rollers 51a and 52a so that the passage time of the temperature raising unit 50 and the heat retaining unit 53 is 10 seconds or less. Therefore, the heating time from temperature increase to heat retention is also 10 seconds or less.

  As described above, according to the heat development apparatus 40 of FIG. 1, in the temperature raising unit 50 that requires uniform heat transfer, the heating guides 51b and 52b and the sheet photosensitive material F are pressed against the heating guides 51b and 52b. Since the sheet photosensitive material F is transported while ensuring contact heat transfer by bringing the sheet photosensitive material F into close contact with the fixed guide surfaces 51d and 52d by the opposing rollers 51a and 52a, the entire surface of the sheet photosensitive material is heated uniformly. Therefore, the finished sheet photosensitive material becomes a high-quality image with suppressed density unevenness.

  Further, after the temperature is raised to the heat development temperature, the sheet holding material 53 conveys the sheet photosensitive material to the gap d between the fixed guide surface 53d of the heating guide 53b and the guide portion 53a by the heat retaining portion 53, and in particular, closely contacts the fixed guide surface 53d. The sheet photosensitive material temperature is still the developing temperature (for example, 123.degree. C.) even if heating is performed in the gap d (heat transfer heating by direct contact with the fixed guide surface 53d and / or heat contact with the surrounding high temperature air). ) Within a predetermined range (for example, 0.5 ° C.). As described above, even if the sheet photosensitive material is conveyed along the wall surface of the heating guide 53b or the curved surface guide 53a in the gap d, the temperature difference of the sheet photosensitive material is less than 0.5 ° C., and a uniform heat retaining state is achieved. Therefore, there is almost no possibility of uneven density in the finished sheet photosensitive material. For this reason, since it is not necessary to provide drive parts, such as a roller, in the heat retention part 53, a score reduction can be achieved.

  Furthermore, since the heating time of the sheet photosensitive material F is 10 seconds or less, a rapid heat development process can be realized, and the heat retaining portion 53 extending in the horizontal direction from the temperature raising portion 50 becomes a curved surface from the middle and becomes vertical. The sheet photosensitive material F is discharged to the sheet photosensitive material placing unit 58 with the sheet photosensitive material F almost reversed in the direction of the sheet photosensitive material F by the cooling unit 54. By using a predetermined curvature, it is possible to reduce the installation area and the size of the entire apparatus.

  In conventional large-scale machines, the sheet photosensitive material has the same heating and conveying mechanism as the heating unit even where the heat-retaining function is sufficient after the temperature is raised to the development temperature, and as a result, unnecessary members are used. In addition, the number of parts and the cost have been increased, and it has been difficult to guarantee high image quality due to the problem of uneven density due to the difficulty in ensuring heat transfer at the time of temperature rise in conventional small machines. On the other hand, according to a preferred embodiment, both the problems can be solved by separately executing the heat development process in the temperature raising unit 50 and the heat retaining unit 53.

  Further, the sheet photosensitive material F is heated from the BC surface side with the silver surface photothermographic dry imaging material coated EC surface being opened by the temperature raising unit 50 and the heat retaining unit 53, so that rapid processing of 10 seconds or less is possible. When the heat development process is performed in step 1, the solvent (water, organic solvent, etc.) contained in the sheet photosensitive material F to be heated and volatilized (evaporated) is dispersed at the shortest distance by heating the EC surface side. Even if the time (volatilization time) is shortened, it becomes difficult to be affected by the shortening of time, and even if there is a part where the contact property between the sheet photosensitive material F and the fixed guide surfaces 51d and 52d is partially poor, the PET on the BC surface Due to the thermal diffusion effect by the base, the temperature difference from the portion with good contact is alleviated, and as a result, the density difference hardly occurs, so that the density can be stabilized and the image quality is stabilized. In general, considering the heating efficiency, it is considered that the EC surface side heating is better, but the thermal conductivity of PET of the support substrate of the sheet photosensitive material F is 0.17 W / m ° C., the thickness of the PET base is Considering that the thickness is around 170 μm, it is preferable that the time delay is slight and can be easily offset by increasing the heater capacity or the like, and the effect of reducing the contact unevenness can be expected.

  Further, the solvent (moisture, organic solvent, etc.) in the sheet photosensitive material F is about to volatilize (evaporate) even after leaving the heat retaining section 53 and reaching the cooling section 54. Since the EC surface of the photosensitive material F is in an open state, the solvent (water, organic solvent, etc.) is not trapped and is volatilized for a longer time, so that the image quality is more stable. Thus, the cooling time cannot be ignored during the rapid processing, and is particularly effective for the rapid processing with a heating time of 10 seconds or less.

  In the present invention, 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 an oxidation-reduction reaction between an organic silver salt (which functions as an oxidizing agent) and a 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 may be on either the photosensitive layer side or the non-photosensitive layer side, but the non-photosensitive layer side is preferably the contact heating surface in terms of stability to the processing environment. The developing unit is preferably configured by combining a plurality of zones and a plurality of means that are independently temperature controlled, and further includes at least one heat retention zone that maintains 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 in the temperature elevation portion, the heating means such as a heating member and the sheet photosensitive material are in close contact with each other. It is not necessary to make such close contact in the thermal insulation part by using the optimal heating method for the temperature rising part and the thermal insulation part. 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 thermal development apparatus, the temperature raising unit heats the sheet photosensitive material while pressing the sheet photosensitive material against a plate heater by a counter roller, and the heat retaining unit is a slit formed between guides having at least one heater. The sheet photosensitive material can be heated inside. In the temperature raising section, the sheet photosensitive material is pressed and brought into contact with the plate heater by the opposing roller, so that the plate heater and the sheet photosensitive material can be brought into close contact with each other, while the heat retaining section is conveyed by the opposing roller in the temperature raising section. Since it is only necessary to heat (keep warm) between the slits with force, no drive parts are required for the conveyance system, and the size of the apparatus can be reduced and the cost can be reduced without requiring much accuracy of the slit dimensions. .

  According to this thermal development apparatus, in the first zone, the sheet photosensitive material is heated by ensuring intimate contact between the heating means such as a heating member and the sheet photosensitive material, and the occurrence of uneven density is suppressed. Since there is no need for close contact, in the second zone, the sheet photosensitive material is kept warm in the guide gap, so that rapid processing of the thermal development process, miniaturization and cost of the apparatus are maintained while maintaining high image quality without density unevenness. Can be configured to be down. When the guide gap is 3 mm or less, there is little effect on the heat retention performance in the second zone regardless of the conveying posture of the sheet photosensitive material, and the positioning accuracy between the fixed guide and another guide is not required so much. The tolerance for the curvature error at the time of machining and the mounting accuracy is increased, resulting in a significant increase in the degree of freedom in design, which can contribute to the 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. A guide gap of 1 mm or more is preferred because the coated surface of the silver salt photothermographic dry imaging material of the sheet photosensitive material is difficult to touch the guide surface, and the possibility of scratches is reduced.

  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 photosensitive material in the temperature raising portion and the heat retaining portion can be configured to be 10 seconds or less, and the period between the temperature raising step and the heat retaining step can be shortened, so that the heat development process can be performed quickly. Processing becomes 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 raising portion enters the concave portion, so that the sheet photosensitive member can be conveyed while the temperature raising portion is conveyed. It is possible to prevent foreign matters accumulated and moved by the material front end portion from being brought into the heat retaining portion, and it is possible to prevent the sheet photosensitive material from being jammed, scratched, or uneven in density.

  In addition, it is preferable that the temperature raising unit and the heat retaining unit are configured to heat the sheet photosensitive material by opening the coated surface side of the silver salt photothermographic dry imaging material. In the cooling unit, it is preferable to cool the silver salt photothermographic dry imaging material by opening the coated surface side.

  However, the mechanism of the heat retaining zone is not limited to the above as long as it is a mechanism that maintains the temperature of the heated sheet photosensitive material. The development time is preferably 5 to 10 seconds.

  The developing device may have a preheat zone in which the silver salt photothermographic dry imaging material is heated to 70 to 100 ° C. after imagewise exposure and before the heat development step of heating at a desired development temperature. Furthermore, it is preferable to heat 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., and more preferably ± 0.5 ° C. The heating time varies depending on the heating mechanism, but is preferably in the range of 0.5 to 7 seconds. Furthermore, it is preferably in the range of 1 to 3 seconds.

  In addition, the developing device is a slow cooling method in which the silver salt photothermographic dry imaging material is imagewise exposed, heated at a desired developing temperature, adjusted to a temperature lower by 10 to 20 ° C. than the thermal developing temperature, and development is stopped. You may have a zone. Furthermore, it is preferable to adjust 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 or more with respect to the development time, and is preferably in the range of x0.25 to x1.0 in view of rapid processing.

  In the present invention, a temperature / humidity sensor is provided in the vicinity of the conveyance path from the sheet photosensitive material storage unit 45 to the temperature raising unit 50, and the development time and the development temperature are controlled based on the measured temperature or humidity. Image quality can be maintained. For example, when the environmental humidity is high, it is possible to stabilize the image density by lowering the development temperature or shortening the development time.

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

Example 1
<< Preparation of undercoated photographic support >>
8 W · min. On both sides of a polyethylene terephthalate sheet photosensitive material having a thickness of 175 μm and biaxially stretched and heat-fixed with an optical density of 0.150 (measured with a Densitometer PDA-65 manufactured by Konica Corporation (former name)) A photographic support subjected to a corona discharge treatment of / m ² was subjected to subbing. That is, the undercoat coating solution a-1 was applied to one surface of this photographic support so that the dry film thickness was 0.2 μm at 22 ° C. and 100 m / min, and dried at 140 ° C. for photosensitivity. A layer (image forming layer) side undercoat layer was formed (referred to as an undercoat underlayer A-1). Moreover, the following undercoat coating liquid b-1 was applied to the opposite surface as a backing layer undercoat layer at 22 ° C. and 100 m / min so that the dry film thickness was 0.12 μm, and dried at 140 ° C. An undercoat conductive layer having an antistatic function (referred to as undercoat underlayer B-1) was applied on the backing layer side. A corona discharge of 8 W · min / m ² is applied to the upper surfaces of the subbing lower layer A-1 and the subbing lower layer B-1, and the following subbing coating solution a-2 is dried on the lower subbing layer A-1. The film was coated at 33 ° C. and 100 m / min so as to have a film thickness of 0.03 μm, and dried at 140 ° C. to form an undercoat upper layer A-2. -2 was coated at 33 ° C. and 100 m / min to a dry film thickness of 0.2 μm, dried at 140 ° C. to form an undercoating upper layer B-2, and the support was further heat treated at 123 ° C. for 2 minutes. The sample was wound up under the conditions of 50 ° C. and 50% RH to prepare a subtracted sample.

[Preparation of aqueous polyester A-1 solution]
35.4 parts by weight of dimethyl terephthalate, 33.63 parts by weight of dimethyl isophthalate, 17.92 parts by weight of dimethyl sodium 5-sulfoisophthalate, 62 parts by weight of ethylene glycol, 0.065 parts by weight of calcium acetate / monohydrate, After transesterification of 0.022 parts by mass of manganese acetate tetrahydrate under a nitrogen stream while distilling off methanol at 170 to 220 ° C., 0.04 parts by mass of trimethyl phosphate and a polycondensation catalyst were used. 0.04 parts by mass of antimony oxide and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and at a reaction temperature of 220 to 235 ° C., a theoretical amount of water was distilled off for esterification.

  Thereafter, the inside of the reaction system was further depressurized and heated over about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to synthesize aqueous polyester A-1. The obtained aqueous polyester A-1 had an intrinsic viscosity of 0.33, an average particle size of 40 nm, and Mw = 80000 to 100,000.

  Next, 850 ml of pure water was placed in a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of aqueous polyester A-1 was gradually added while rotating the stirring blade. After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours and 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 15% by mass aqueous polyester A-1 solution.

[Preparation of Modified Aqueous Polyester B-1-2 Solution]
Into a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer and a dropping funnel, 1900 ml of the 15% by mass aqueous polyester A-1 solution was placed, and the internal temperature was adjusted to 80 ° C. while rotating the stirring blade. Until heated. Into this, 6.52 ml of a 24 mass% 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 is continued for another 3 hours. Then, it cooled and filtered to 30 degrees C or less, and prepared the modified aqueous polyester B-1 solution (vinyl-type component modification | denaturation ratio 20 mass%) whose solid content concentration is 18 mass%.

  The solid content concentration was the same except that the vinyl modification ratio was 36% by mass and the modified components were styrene: glycidyl methacrylate: acetoacetoxyethyl methacrylate: n-butyl acrylate = 39.5: 40: 20: 0.5. An 18% by mass modified aqueous polyester B-2 solution (vinyl component modification ratio 20% by mass) was prepared.

[Production of Acrylic Polymer Latex C-1 to C-3]
Acrylic polymer latexes C-1 to C-3 having the monomer composition shown in Table 1 were synthesized by emulsion polymerization. The solid content concentration was 30% by mass.

[Coating liquid a-1 for photosensitive layer side undercoat layer]
Acrylic polymer latex C-3 (solid content 30%) 70.0 g
Water dispersion of ethoxylated alcohol and ethylene homopolymer (10% solids)
5.0g
Surfactant (A) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

<< Coating liquid a-2 for photosensitive layer side undercoat upper layer >>
Modified aqueous polyester B-2 (18% by mass) 30.0 g
Surfactant (A) 0.1g
Spherical silica matting agent (Nippon Shokubai Co., Ltd. Sea Hoster KE-P50)
0.04g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

[Backing layer side undercoat coating solution b-1]
Acrylic polymer latex C-1 (solid content 30%) 30.0 g
Acrylic polymer latex C-2 (solid content 30%) 7.6 g
SnO ₂ sol 180g
(SnO ₂ sol synthesized by the method described in Example 1 of Japanese Patent Publication No. 35-6616 was heated and concentrated so that the solid content concentration was 10% by mass, and then adjusted to pH = 10 with ammonia water)
Surfactant (A) 0.5g
PVA-613 (PVA manufactured by Kuraray Co., Ltd.) 5% by weight aqueous solution 0.4 g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

[Backing layer side undercoat upper layer coating solution b-2]
Modified aqueous polyester B-1 (18% by mass) 145.0 g
True spherical silica matting agent (Nippon Shokubai Co., Ltd. Sea Hoster KE-P50) 0.2g
Surfactant (A) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

  A backcoat layer and a backcoat layer protective layer having the following composition were coated on the undercoat layer B-2 of the support on which the undercoat layer had been applied.

<Preparation of backcoat layer coating solution>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate propionate (manufactured by Eastman Chemical: CAP482-20) and 4.5 g of polyester resin (Bostic: VitelPE2200B) were added and dissolved. Next, 0.30 g of the following infrared dye 1 was added to the dissolved solution, and 4.5 g of a fluorosurfactant (manufactured by Asahi Glass Co., Ltd .: Surflon KH40) and a fluorosurfactant dissolved in 43.2 g of methanol. 2.3 g (Dainippon Ink Co., Ltd .: MegaFag F120K) was added and stirred well until dissolved. Next, 2.5 g of oleyl oleate was added and stirred to prepare a backcoat layer coating solution.

<Preparation of backcoat layer protective layer (surface protective layer) coating solution>
The backcoat layer protective layer was also prepared in the same manner as the backcoat layer coating solution at the following composition ratio. Silica was dispersed in MEK at a concentration of 1% with a dissolver type homogenizer, and finally added.

Cellulose acetate propionate (10% MEK solution) 12.8 g
(Manufactured by Eastman Chemical: CAP482-20)
Amorphous saturated copolyester (Toyobo Co., Ltd .: Byron 240P) 2.2g
Monodispersed silica having a monodispersity of 15% (average particle size: 10 μm) 0.03 g
(Surface treatment with 1% aluminum of the total mass of silica)
0.02 g of ethylenediaminebisstearic acid amide (average particle size: 10 μm)
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.075 g
Fluorine-based surfactant (SF-17) 0.01g
Fluoropolymer (FM-1) 0.05g
Stearic acid 0.1g
0.1 g butyl stearate
α-Alumina (Mohs hardness 9) 0.1g

<Preparation of photosensitive silver halide grain emulsion A1>
(A1)
Phenylcarbamoylated gelatin 88.3g
10% aqueous methanol solution of compound (AO-1) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water.

(B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(C1)
Potassium bromide 50.69g
Potassium iodide 2.66g
Finish to 660 ml with water.

(D1)
Potassium bromide 151.6g
Potassium iodide 7.67g
Hexachloroiridium (IV) acid potassium: K ₂ (IrCl ₆ ) (1% aqueous solution)
0.93ml
Potassium hexacyanoferrate (II) 0.004g
Hexachloroosmium (IV) potassium salt 0.004g
Finish to 1982 ml with water.

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

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

  Using the mixing stirrer shown in Japanese Patent Publication No. 58-58288, while controlling 1/4 of the solution (B1) in the solution (A1) and the total amount of the solution (C1) to 20 ° C. and pAg 8.09, the simultaneous mixing method Was added for 4 minutes and 45 seconds to nucleate. After 1 minute, the entire amount of solution (F1) was added. During this time, pAg was adjusted as appropriate using (E1). After 6 minutes, 3/4 amount of the solution (B1) and the total amount of the solution (D1) were added by a simultaneous mixing method over 14 minutes and 15 seconds while controlling at 20 ° C. and pAg 8.09. After stirring for 5 minutes, the temperature was lowered to 40 ° C., the whole amount of the solution (G1) was added, and the silver halide emulsion was allowed to settle. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, the silver halide grain emulsion was allowed to settle. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution (H1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount of silver was 1161 g per mole of silver, to obtain photosensitive silver halide grain emulsion A1.

  This emulsion was monodisperse cubic silver iodobromide grains having an average grain size of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (AgI content is 3.5 mol%).

[Preparation of photosensitive silver halide grain emulsion A2]
In the preparation of the above light-sensitive silver halide emulsion A1, after adding the entire amount of the solution F1 after nucleation, 40 ml of a 5% aqueous solution of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene was added. A photosensitive silver halide emulsion A2 was prepared in the same manner as described above.

  The grains in this emulsion were monodispersed cubic silver iodobromide grains having an average grain size of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (AgI content was 3.5 mol). %).

[Preparation of photosensitive silver halide grain emulsion A3]
In the preparation of the photosensitive silver halide emulsion A1, the photosensitive halogenation was similarly carried out except that 4 ml of a 0.1% ethanol solution of the following compound (TPPS) was added after the whole amount of the solution F1 was added after nucleation. Silver grain emulsion A3 was prepared.

  The grains in this emulsion were monodispersed cubic silver iodobromide grains having an average grain size of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (AgI content was 3.5 mol). %).

<Preparation of photosensitive silver halide grain emulsion B1>
The procedure was the same as the preparation of the photosensitive silver halide grain emulsion A1, except that the temperature at the time of addition by the simultaneous mixing method was changed to 45 ° C. The grains in this emulsion were monodisperse cubic silver iodobromide grains having an average grain size of 55 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (AgI content is 3.5 mol%). .

<Preparation of photosensitive silver halide grain emulsion B2>
In the preparation of the photosensitive silver halide grain emulsion B1, the photosensitive halogen halide was similarly treated except that 4 ml of a 0.1% ethanol solution of the above compound (TPPS) was added after adding the whole amount of the solution F1 after nucleation. A silver halide grain emulsion B2 was prepared. The grains in this emulsion were monodisperse cubic silver iodobromide grains having an average grain size of 55 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (AgI content is 3.5 mol%). .

<Preparation of powdered organic silver salt>
130.8 g of behenic acid, 67.7 g of arachidic acid, 43.6 g of stearic acid, and 2.3 g of palmitic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 mol / L potassium hydroxide aqueous solution was added and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain a fatty acid potassium solution. While maintaining the temperature of the fatty acid potassium solution at 55 ° C., photosensitive silver halide grain emulsions A1, A2, A3, B1, B2 (types and addition amounts are listed in Table 2) and 450 ml of pure water were added. Stir for minutes. Next, 468.4 ml of 1 mol / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an organic silver salt dispersion. Thereafter, the obtained organic silver salt dispersion was transferred to a water-washing container, deionized water was added and stirred, and then allowed to stand to float and separate the organic silver salt dispersion, thereby removing the lower water-soluble salts. Thereafter, washing with deionized water and drainage were repeated until the electrical conductivity of the drainage reached 2 μS / cm, and centrifugal dehydration was carried out. Then, the obtained cake-like organic silver salt was converted into an air-flow dryer Flashjet dryer (Seishin). A powder organic silver salt that has been dried and dried to a moisture content of 0.1% under the operating conditions (inlet 65 ° C., outlet 40 ° C.) of nitrogen gas atmosphere and dryer hot air temperature Obtained. In addition, the infrared moisture meter was used for the moisture content measurement of an organic silver salt composition.

<Preparation of preliminary dispersion>
As a binder for the photosensitive layer (image forming layer), 14.57 g of SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing 0.2 mmol / g of —SO ₃ K group) was dissolved in 1457 g of MEK, and VMA-GETZMANN While stirring with a dissolver DISPERMAT CA-40M type, 500 g of the powdered organic silver salt was gradually added and mixed well to prepare a preliminary dispersion.

<Preparation of photosensitive emulsion dispersion>
Media type disperser DISPERMAT SL 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 1.5 minutes using a pump. A photosensitive emulsion dispersion was prepared by supplying to -C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<Preparation of stabilizer solution>
A stabilizer solution was prepared by dissolving 1.0 g of Stabilizer 1 and 0.31 g of potassium acetate in 4.97 g of methanol.

<Preparation of infrared sensitizing dye liquid A>
9.6 mg of infrared sensitizing dye 1, 9.6 mg of infrared sensitizing dye 2, 1.488 g of 2-chlorobenzoic acid, 2.779 g of stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenz Infrared sensitizing dye solution A was prepared by dissolving imidazole in 31.3 ml of MEK in the dark.

<Preparation of additive solution a>
Reducing agent (compounds and amounts listed in Table 2), 0.159 g of yellow chromophoric leuco dye YA-1 of general formula (YB), 0.159 g of cyan chromogenic leuco dye CLA-4, 1.54 g of 4 -Methylphthalic acid, 0.48 g of the infrared dye 1 was dissolved in 110.0 g of MEK to obtain an additive solution a.

<Preparation of additive liquid b>
1.25 g antifoggant 2, 0.5 g antifoggant 3, 0.5 g antifoggant 4, 0.5 g antifoggant 5, 3.43 g phthalazine dissolved in 40.9 g MEK and added b.

<Preparation of additive liquid c>
A silver saving agent (type and amount described in Table 2) was dissolved in 39.95 g of MEK to obtain an additive solution c.

<Preparation of additive liquid d>
0.1 g of supersensitizer 1 was dissolved in 9.9 g of MEK to obtain additive solution d.

<Preparation of additive liquid e>
0.5 g of potassium p-toluenethiosulfonate and 0.5 g of antifoggant 6 were dissolved in 9.0 g of MEK to obtain an additive solution e.

<Preparation of additive liquid f>
An antifoggant containing 1.0 g of vinyl sulfone [(CH ₂ ═CH—SO ₂ CH ₂ ) ₂ CHOH] was dissolved in 9.0 g of MEK to obtain an additive solution f.

<Preparation of photosensitive layer coating solution>
In an inert gas atmosphere (nitrogen 97%), 50 g of the photosensitive emulsion dispersion (described in Table 2) and 15.11 g of MEK were kept at 21 ° C. with stirring, and the chemical sensitizer S-5 (0. 5% methanol solution) 1000 μl was added, and after 2 minutes, 390 μl of antifoggant 1 (10% methanol solution) was added and stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 10 minutes, then gold sensitizer Au-5 corresponding to 1/20 mole of the above organic chemical sensitizer was added, and further stirred for 20 minutes. . Subsequently, 167 μl of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While maintained at 13 ° C., adding liquid d of 0.5g, added solution e of 0.5g, additive solution f of 0.5g, SO ₃ K group containing polyvinyl butyral (Tg of 75 ° C., the -SO ₃ K groups 0. After adding 13.31 g (containing 2 mmol / g) and stirring for 30 minutes, 1.084 g of tetrachlorophthalic acid (9.4% MEK solution) was added and stirred for 15 minutes. While continuing to stir, 12.43 g of additive liquid a, 1.6 ml of Desmodur N3300 / Mobey aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b, 4.0 g of additive liquid c By sequentially adding and stirring, a photosensitive layer coating solution was obtained.

  The chemical structures of the additives used for the preparation of each coating solution including the stabilizer solution and the photosensitive layer coating solution are shown below.

<Preparation of photosensitive layer protective layer lower layer (surface protective layer lower layer)>
Acetone 5g
MEK 21g
Cellulose acetate propionate 2.3g
(Manufactured by Eastman Chemical: CAP-141-20, glass transition temperature Tg = 190 ° C.)
7g of methanol
Phthalazine 0.25g
_{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2 0.035g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorine-based surfactant (SF-17: supra) 0.01g
Stearic acid 0.1g
0.1 g butyl stearate
α-Alumina (Mohs hardness 9) 0.1g
<Preparation of photosensitive layer protective layer upper layer (surface protective layer upper layer)>
Acetone 5g
21g of methyl ethyl ketone
Cellulose acetate propionate 2.3g
(Manufactured by Eastman Chemical: CAP-141-20 glass transition temperature Tg = 190 ° C.)
Paraloid A-21 (Rohm and Haas) 0.08g
Benzotriazole 0.03g
7g of methanol
Phthalazine 0.25g
Monodispersed 15% monodispersed silica (average particle size: 3 μm) 0.140 g
(Surface treatment with 1% by mass of aluminum based on the total mass of silica)
_{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2 0.035g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorosurfactant (SF-17: supra) 0.005g
Fluoropolymer (FM-1: supra) 0.01g
Stearic acid 0.1g
0.1 g butyl stearate
α-Alumina (Mohs hardness 9) 0.1g
The upper layer and the lower layer of the photosensitive layer protective layer were formed by the same method as the preparation of the backcoat layer coating solution at the above composition ratio. As for the silica, similarly to the backcoat layer protective layer, MEK was dispersed with a dissolver type homogenizer at a concentration of 1% by mass, and finally added and stirred to obtain a coating solution for the upper and lower layers of the photosensitive layer protective layer. .

<Production of silver salt photothermographic dry imaging materials>
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared as described above were extruded onto the undercoating upper layer B-2 so that the dry film thickness was 1.5 μm, respectively, and the coating speed was 50 m / Application was performed in min. The drying was performed for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C.

  The photosensitive layer coating solution and the photosensitive layer protective layer (surface protective layer) coating solution are simultaneously coated on the subbing upper layer A-2 at an application speed of 50 m / min using an extrusion coater. Thus, silver salt photothermographic dry imaging material samples 101 to 119 shown in Table 2 were prepared. The coating is carried out with the values described in Table 2 for the dry film thickness of the photosensitive layer, and the photosensitive layer protective layer (surface protective layer) has a dry film thickness of 3.0 μm (surface protective layer upper layer 1.5 μm, surface Then, drying was performed for 10 minutes using drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

  The film surface pH of the obtained silver salt photothermographic dry imaging material (sample 115) on the photosensitive layer side is 5.3, the Beck smoothness is 6000 seconds, and the film surface pH on the backcoat layer side is 5.5. The Beck smoothness was 12000 seconds. Moreover, when the surface roughness was measured about the samples 101-119, they were Rz (E) / Rz (B) = 0.33 and Rz (E) = 1.4 micrometers. Rz (B) was 4.3 μm. Ra (E) was 0.09 μm. Ra (B) was 0.15 μm. Regarding samples 101 to 119, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed. Further, in Samples 101 to 119, an absorption peak at a maximum absorption wavelength of 620 nm due to the cyan color-forming leuco dye was observed.

  For sample 113, in the preparation of powdered organic silver salt A in sample 102, instead of behenic acid 130.8 g, arachidic acid 67.7 g, stearic acid 43.6 g, and palmitic acid 2.3 g, behenic acid 259. A sample was prepared in the same manner as Sample 102 except that 4 g and arachidic acid 0.5 g were used.

Sample 114 was the same as Sample 102 except that the fluorine-based activator of the backcoat layer protective layer and the photosensitive layer protective layer (upper layer and lower layer) in Sample 102 was changed from SF-17 to C ₈ F ₁₇ SO ₃ Li. A sample was prepared.

<Exposure and development processing>
After processing the silver salt photothermographic dry imaging material samples 101 to 119 produced as described above into half-cut size (34.5 cm × 43.0 cm), the sample is packaged in the following packaging material in an environment of 25 ° C. and 50%, After storing at room temperature for 2 weeks, the following evaluation was performed.

(Packaging material)
PET 10 μm / PE 12 μm / Aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% carbon, oxygen permeability: 0.02 ml / m ² per day at 25 ° C. and 1.013 × 10 ⁵ Pa, moisture permeability: 0.001 g / Barrier bag of m ² · 40 ° C · 90% RH · day (according to JIS Z0208 cup method). Use paper tray.

(Sample evaluation)
<Exposure and development processing>
After processing the silver salt photothermographic dry imaging material samples 1 to 119 produced as described above to a half-cut size (34.5 cm × 43.0 cm), the thermal development apparatus shown in FIG. Mounting, installation area 0.35 m ² ) and thermal development simultaneously with exposure (51, 52 and 53 in FIG. And conveyed so as to be in contact for a total of 10 seconds. Here, “thermal development at the same time as exposure” means a sheet photosensitive material made of a silver salt photothermographic dry imaging material, which is a part of the sheet photosensitive material that has already been exposed while being partially exposed. It means that development is started. The distance between the exposed part and the developing part was 12 cm, and the linear velocity at this time was 30 mm / second. At this time, the transport speed from the silver salt photothermographic dry imaging material supply apparatus section to the image exposure apparatus section, the transport speed in the image exposure section, and the transport speed in the thermal development section were each 30 mm / second. In addition, the position of the bottom of the silver salt photothermographic dry imaging material stock tray located at the bottom was 45 cm high from the floor. Further, the time required for the heat development processing (the time required for the silver salt photothermographic dry imaging material to be picked up and discharged from the tray portion) was 45 seconds. (In the case of continuous processing, the interval time for heat development is 4 seconds.) The exposure was performed in a stepped manner while reducing the exposure energy amount by log E0.05 step by step from the maximum output.

<Performance evaluation>
The following performance was evaluated for each heat-developed image.

<< Image density Dmax >>
The value of the highest density portion of the image obtained under the above conditions was measured with a densitometer and indicated as the image density.

"Fog Dmin"
The value of the unexposed portion of the image obtained under the above conditions was measured with a densitometer and indicated as fog density.

《Gamma value》
The optical density of the obtained silver salt photothermographic dry imaging material was measured, and the gamma value was calculated. The gamma value was expressed in terms of gamma at an optical density of 1.2 in the characteristic curve when the silver salt photothermographic dry imaging material was heat-developed. The photographic characteristic curve is a D-logE curve representing the relationship between the logarithm of logarithm (log E) of the exposure amount as exposure energy on the horizontal axis and the optical density, that is, the scattered light photographic density (D) on the horizontal axis. Say. The gamma (γ) value is a tangent slope at the optical density D = 1.2 on the characteristic curve (tan θ when the angle between the tangent and the horizontal axis is θ).

《Sharpness》
The obtained image was visually observed, and the sharpness was evaluated in 0.5 increments according to the evaluation criteria shown below.

5.0 Very sharp image 4.0 Sharp image 3.0 Good but slightly blurred 2.0 Blur is conspicuous and slightly disturbed interpretation 1.0 Difficult to interpret due to blur 《Density unevenness during heat development》
The density unevenness after development was evaluated visually by 0.5 increments according to the following criteria.

5: Generation of density unevenness is not observed 4: Slight density unevenness occurs 3: Weak density unevenness occurs in part 2: Strong density unevenness occurs in part 1: Strong density unevenness occurs over the entire surface << Light irradiation Image preservation
After each silver salt photothermographic dry imaging material sample was exposed and developed in the same manner as described above, it was attached to a 1000 lux Schaukasten and allowed to stand for 10 days. Evaluation was made in increments of 5.

5: Almost no change 4: Slight color change observed 3: Partial color change and fog increase observed 2: Color change and fog increase observed in considerable part 1: Color change and fog increase Table 2 shows the results of the remarkable increase and the occurrence of strong density unevenness on the entire surface.

  In addition, when a paper tray with silica gel is used in the sample 102 with a raised paper tray and silica gel sealed in the space formed at the bottom of the tray, the concentration fluctuation due to humidity fluctuation is 0.0, and an improvement effect is recognized. It was.

Example 2
<< Preparation of undercoated photographic support >>
It was produced in the same manner as in Example 1.

<Preparation of backcoat layer coating solution>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate propionate (manufactured by Eastman Chemical: CAP482-20) and 4.5 g of polyester resin (Bostic: VitelPE2200B) were added and dissolved. Next, 0.30 g of the following yellow dye 1 was added to the dissolved liquid, and 4.5 g of a fluorosurfactant (Asahi Glass Co., Ltd .: Surflon KH40) dissolved in 43.2 g of methanol and a fluorosurfactant ( 2.3 g) (manufactured by Dainippon Ink & Co., Inc .: MegaFag F120K) was added and sufficiently stirred until dissolved. Next, 2.5 g of oleyl oleate was added. Finally, 75 g of silica (average particle size: 10 μm) dispersed in MEK with a dissolver type homogenizer at a concentration of 1% was added and stirred to prepare a backcoat layer coating solution.

<Preparation of backcoat layer protective layer (surface protective layer) coating solution>
The following composition ratio was prepared in the same manner as the back coat layer coating solution. A dissolver type homogenizer was used for dispersion of silica.

Cellulose acetate propionate (10% MEK solution) 15g
(Manufactured by Eastman Chemical: CAP482-20)
Monodispersed silica having a monodispersity of 15% (average particle size: 10 μm) (surface treatment with 1% aluminum of the total mass of silica) 0.03 g
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.05 g
Fluorine-based surfactant (SF-17) 0.01g
Fluoropolymer (FM-1) 0.05g
Stearic acid 0.1g
0.1 g butyl stearate
α-Alumina (Mohs hardness 9) 0.1g
<Preparation of photosensitive silver halide grain emulsion A1>
This is the same as the preparation of photosensitive silver halide grain emulsion A1 in Example 1.

<Preparation of photosensitive silver halide grain emulsion B1>
This is the same as the preparation of the photosensitive silver halide grain emulsion B1 in Example 1.

<Preparation of photosensitive silver halide emulsion C>
The procedure was the same as the preparation of the photosensitive silver halide grain emulsion A1, except that the potassium bromide used in the preparation of the photosensitive silver halide grain emulsion A1 was changed to potassium iodide. The grains in the emulsion were monodispersed pure silver iodide grains having an average grain size of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

<Preparation of photosensitive silver halide grain emulsion D>
Preparation of photosensitive silver halide emulsion A1 except that part of the potassium bromide used in the preparation of photosensitive silver halide grain emulsion A1 was changed to potassium iodide so that the silver iodide content was 90 mol%. As well as. The grains in this emulsion were monodispersed silver iodobromide grains having an average grain size of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (silver iodide content was 90 mol%). )

<Preparation of photosensitive silver halide grain emulsion E>
The same procedure as in the preparation of photosensitive silver halide emulsion C was carried out except that the temperature at the time of addition by the simultaneous mixing method was changed to 45 ° C. The grains in this emulsion were monodispersed pure silver iodide grains having an average grain size of 55 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

<Preparation of photosensitive silver halide grain emulsion F>
The procedure was the same as the preparation of the photosensitive silver halide emulsion D except that the temperature at the time of addition by the simultaneous mixing method was changed to 45 ° C. The grains in this emulsion were monodispersed silver iodobromide grains having an average grain size of 55 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92% (silver iodide content was 90 mol%). ).

<Preparation of photosensitive silver halide grain emulsion G>
In the preparation of the photosensitive silver halide emulsion C, the photosensitive halogenation was similarly performed except that 4 ml of a 0.1% ethanol solution of the above compound (TPPS) was added after the addition of the whole amount of the solution F1 after nucleation. Silver grain emulsion G was prepared.

  The grains in this emulsion were monodispersed pure silver iodide grains having an average grain diameter of 25 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

<Preparation of photosensitive silver halide grain emulsion H>
In the preparation of the above photosensitive silver halide grain emulsion E, the photosensitive halogen halide was similarly prepared except that 4 ml of a 0.1% ethanol solution of the above compound (TPPS) was added after the addition of the whole amount of the solution F1 after nucleation. A silver halide grain emulsion H was prepared.

  The grains in this emulsion were monodispersed pure silver iodide grains having an average grain size of 55 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

<Preparation of powdered organic silver salt>
130.8 g of behenic acid, 67.7 g of arachidic acid, 43.6 g of stearic acid, and 2.3 g of palmitic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 mol / L sodium hydroxide aqueous solution was added and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the fatty acid sodium solution at 55 ° C., photosensitive silver halide grain emulsions C, D, E, F, G, H (types and addition amounts are listed in Table 3) and 450 ml of pure water were added And stirred for 5 minutes. Next, 468.4 ml of 1 mol / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an organic silver salt dispersion. Thereafter, the obtained organic silver salt dispersion was transferred to a water-washing container, deionized water was added and stirred, and then allowed to stand to float and separate the organic silver salt dispersion, thereby removing the lower water-soluble salts. Thereafter, washing with deionized water and drainage were repeated until the electrical conductivity of the drainage reached 2 μS / cm, and centrifugal dehydration was carried out. Then, the obtained cake-like organic silver salt was converted into an air-flow dryer Flashjet dryer (Seishin). A powder organic silver salt that has been dried and dried to a moisture content of 0.1% under the operating conditions (inlet 65 ° C., outlet 40 ° C.) of nitrogen gas atmosphere and dryer hot air temperature I got each.

<Preparation of preliminary dispersion>
Preliminary dispersions were prepared in the same manner as the preliminary dispersion in Example 1, except that the powdered organic silver salt was replaced with the powdered organic silver salt obtained above.

<Preparation of photosensitive emulsion dispersion>
Media type disperser DISPERMAT SL 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 1.5 minutes using a pump. A photosensitive emulsion dispersion was prepared by feeding to a -C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<Preparation of Stabilizer Solution 1>
Stabilizer solution 1 was prepared by dissolving 1.0 g of Stabilizer 1 and 0.31 g of potassium acetate in 4.97 g of methanol.

<Preparation of 2-chlorobenzoic acid solution>
1.488 g of 2-chlorobenzoic acid, 2.779 g of stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenzimidazole are dissolved in 31.3 ml of MEK in the dark to prepare a 2-chlorobenzoic acid solution. did.

<Preparation of additive liquid a1>
Reducing agent (compound described in Table 3 (reducing agent) and amount), 0.159 g of yellow chromophoric leuco dye (YA-1), 0.159 g of cyan chromogenic leuco dye (CLA-4), 0.48 g The yellow dye 1, 1.54 g of 4-methylphthalic acid was dissolved in 110 g of MEK to obtain an additive solution a1.

<Preparation of additive liquid b1>
1.25 g antifoggant 2, 0.5 g antifoggant 3, 0.5 g antifoggant 4, 0.5 g antifoggant 5, 3.43 g phthalazine dissolved in 40.9 g MEK and added b1.

<Preparation of additive liquid c1>
A silver saving agent (type and amount added is described in Table 3) was dissolved in 39.95 g of MEK to obtain an additive solution c1.

<Preparation of additive solution d1>
0.5 g of potassium p-toluenethiosulfonate and 0.5 g of antifoggant 6 were dissolved in 9.0 g of MEK to obtain an additive solution d1.

<Preparation of additive liquid e1>
1.0 g of vinyl sulfone [(CH ₂ ═CH—SO ₂ CH ₂ ) ₂ CHOH] was dissolved in 9.0 g of MEK to obtain an additive solution e1.

<Preparation of photosensitive layer coating solution>
In an inert gas atmosphere (nitrogen 97%), 50 g of the photosensitive emulsion dispersion (described in Table 3) and 15.11 g of MEK were kept at 21 ° C. with stirring, and the chemical sensitizer S-5 (0. 5% methanol solution) 1000 μl was added, and after 2 minutes, 390 μl of antifoggant 1 (10% methanol solution) was added and stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added and stirred for 10 minutes, then gold sensitizer Au-5 corresponding to 1/20 mole of the above organic chemical sensitizer was added, and further stirred for 20 minutes. . Subsequently, 167 μl of stabilizer solution 1 was added and stirred for 10 minutes, and then 1.32 g of the 2-chlorobenzoic acid solution was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While keeping the temperature at 13 ° C., 0.5 g of additive solution d1, 0.5 g of additive solution e1, SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing —SO ₃ K group of 0.2 mmol / g) After adding 31 g and stirring for 30 minutes, 1.084 g of tetrachlorophthalic acid (9.4% MEK solution) was added and stirred for 15 minutes. While further stirring, 12.43 g of additive liquid a1, 1.6 ml of Desmodur N3300 / Movey aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b1, 1.0 g of additive liquid c1 By sequentially adding and stirring, a photosensitive layer coating solution was obtained.

<Preparation of photosensitive layer protective layer lower layer (surface protective layer lower layer)>
To 500 g of acetone, 2100 g of MEK and 700 g of methanol, 230 g of cellulose acetate butyrate (manufactured by Eastman Chemical: CAB-171-15S) was added, and the mixture was stirred and dissolved with a dissolver. Then 25 g of phthalazine,
3.5g of _{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2,
1 g of C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ ,
1 g of the compound SF-17 represented by the general formula (SF),
10 g of stearic acid,
10 g of butyl stearate was added and dissolved while stirring to prepare a photosensitive layer protective layer lower layer coating solution.

<Preparation of photosensitive layer protective layer upper layer (surface protective layer upper layer)>
To 500 g of acetone, 2100 g of MEK and 700 g of methanol, 230 g of cellulose acetate butyrate (manufactured by Eastman Chemical: CAB-171-15S) was added, and the mixture was stirred and dissolved with a dissolver. Then 25 g of phthalazine,
3.5g of _{CH 2 = CHSO 2 CH 2 CH} 2 OCH 2 CH 2 SO 2 CH = CH 2,
1 g of C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ ,
0.5 g of the compound SF-17 represented by the general formula (SF),
1.0 g of fluoropolymer (FM-1: supra),
10 g of stearic acid,
10 g of butyl stearate was added with stirring and dissolved.

  Finally, 280 g of 15% monodispersed silica (average particle size 10.0 μm, surface treatment with 1% aluminum of the total mass of silica) dispersed in MEK with a dissolver type homogenizer at a concentration of 5% is added and stirred. Then, a photosensitive layer protective layer upper layer coating solution was prepared.

<Production of silver salt photothermographic dry imaging materials>
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared as described above were extruded onto the undercoating upper layer B-2 so that the dry film thickness was 1.5 μm, respectively, and the coating speed was 50 m / Application was performed in min. The drying was performed for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C.

  The photosensitive layer coating solution and the photosensitive layer protective layer (surface protective layer) coating solution are simultaneously coated on the subbing upper layer A-2 at an application speed of 50 m / min using an extrusion coater. Thus, silver salt photothermographic dry imaging material samples 201 to 219 shown in Table 3 were prepared. As for the coating, the dry thickness of the photosensitive layer is the value described in Table 3, and the protective thickness of the photosensitive layer (surface protective layer) is 3.0 μm (surface protective layer upper layer 1.5 μm, surface protective layer) Then, drying was performed for 10 minutes using drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C. Moreover, when the surface roughness was measured about the samples 201-218, they were Rz (E) / Rz (B) = 0.40 and Rz (E) = 1.4 micrometers. Rz (B) was 3.5 μm. Ra (E) was 0.09 μm. Ra (B) was 0.12 μm.

  With respect to Samples 201 to 219, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed. Further, with respect to Samples 201 to 219, an absorption peak having a maximum absorption wavelength of 620 nm due to the cyan coloring leuco dye was observed.

  For sample 214, in the preparation of powdered organic silver salt A in sample 203, behenic acid 259. instead of 130.8 g behenic acid, 67.7 g arachidic acid, 43.6 g stearic acid, and 2.3 g palmitic acid were used. A sample was prepared in the same manner as Sample 203 except that 4 g and arachidic acid 0.5 g were used.

Sample 215 is the same as Sample 203 except that the fluorine-based activator of the backcoat layer protective layer and the photosensitive layer protective layer (upper layer and lower layer) in Sample 203 is changed from SF-17 to C ₈ F ₁₇ SO ₃ Li. A sample was prepared.

(Sample evaluation)
<Exposure and development processing>
After processing the silver salt photothermographic dry imaging material samples 201 to 219 prepared as described above into half-cut size (34.5 cm × 43.0 cm), the same as in Example 1 using the heat development apparatus shown in FIG. Then, exposure and development processing were performed. However, in place of the 810 nm semiconductor laser as an exposure source, a vertical multimode semiconductor laser (NLHV3000E from Nichia Corporation) having a maximum output of 50 mW and an emission wavelength of 405 nm was used.

(Packaging material)
The same material as in Example 1 was used.

<Performance evaluation>
The following performance was evaluated for each heat-developed image.

<< Image density Dmax >>
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

"Fog Dmin"
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

《Gamma value》
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

《Sharpness》
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

《Density unevenness during heat development》
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

《Light irradiation image storage stability》
The same evaluation as in Example 1 was performed, and the results are shown in Table 3.

  In Sample 203, when a paper tray with a raised paper tray and a silica gel sealed in the space formed at the bottom of the tray was used, the concentration fluctuation due to humidity fluctuation was 0.0, and the improvement effect was recognized. It was.

  As shown in Tables 2 and 3, the dry thickness of the photosensitive layer was 8.0 μm to 16.0 μm, the highly active reducing agent represented by the general formula (RD1) was used as the reducing agent, and the γ value was It turns out that the highest density and sharpness of the image after heat development are improving significantly by setting it to 4.1-6.0.

Example 3
<Preparation of underdrawn support>
It was produced in the same manner as in Example 1.

<Preparation of silver halide-containing aliphatic carboxylic acid silver salt emulsion for photosensitive layer>
<Preparation of silver halide emulsion>
(Solution A1)
Phthalated gelatin (phthalated modification rate 99%) 66.2g
Surfactant AO-1 (10% methanol aqueous solution) 10 ml
Potassium bromide 0.32g
Water finish 5429ml 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 B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(Solution C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finish to 660 ml with water (Solution D1)
Potassium bromide 154.9g
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 E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount (solution F1)
Potassium hydroxide 0.71g
Finish to 20 ml with water (Solution G1)
56% aqueous acetic acid solution 10.0ml
(Solution H1)
Anhydrous sodium carbonate 1.16g
Finish to 107 ml with water Using a mixing stirrer shown in Japanese Patent Publication No. 58-58288, while mixing 1/4 of solution B1 and total amount of solution C1 to 35 ° C. and pAg of 8.09, simultaneously mixing The nucleation was performed by adding 4 minutes and 45 seconds by the method. After 1 minute, the entire amount of solution F1 was added. During this period, the solution E1 was appropriately used for adjusting the pAg. After 6 minutes, 3/4 amount of the solution B1 and the whole amount of the solution D1 were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling 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 the solution G1 was added, and the silver halide emulsion was precipitated. The supernatant was removed leaving 2000 ml of the sediment, 10 liters of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 liters of water was further added, and after stirring, the silver halide emulsion was precipitated. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution H1 was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 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 emulsion.

  This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 0.043 μm and a [100] face ratio of 92%.

<Preparation of amphiphilic polymer for dispersion>
A 0.5 liter four-necked separable flask is equipped with a dropping device, thermometer, nitrogen gas inlet tube, stirring device and reflux condenser, and 50 g of methyl ethyl ketone (MEK), 20 g of diacetone acrylamide, methoxypolyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd .: Blenmer PME-400) 20 g, stearoxy polyethylene glycol monomethacrylate (Nippon Yushi Co., Ltd .: Blenmer PSE-400) 20 g, and further lauryl peroxide 0.12 g were charged and heated to 80 ° C. Further, a solution obtained by dissolving 40 g of Ni-propyl acrylamide in 43 g of MEK was dropped into a separable flask over 2 hours. Thereafter, the temperature was raised over 1 hour, and when the mixture was refluxed, a solution obtained by dissolving 0.17 g of lauryl peroxide in 33 g of MEK was dropped into the flask over 2 hours and reacted at the same temperature for further 3 hours. . Thereafter, a solution obtained by dissolving 0.33 g of methylhydroquinone in 107 g of MEK was added, and after cooling, a polymer solution for amphiphilic dispersion of 30% polymer was obtained. The molecular weight was about 55,000 in terms of polystyrene-equivalent weight average molecular weight by GPC (gel permeation chromatography). Subsequently, the polymer solution was dropped into a sufficient amount of water, the supernatant was removed, and the polymer solid content was taken out.

<Preparation of silver halide grain amphiphilic dispersion>
67 g of methanol was added to 10 g of the polymer solid content for amphiphilic dispersion and dissolved at 45 ° C. with stirring for 30 minutes. Thereto, 25 g of the silver halide emulsion adjusted to 45 ° C. was added dropwise over 2 minutes, and the mixture was further stirred for 30 minutes. After the temperature of this liquid is lowered to 18 ° C., the liquid left for 30 minutes is separated into two layers. The supernatant of the liquid was removed, 230 g of MEK was added to the remaining liquid, and distilled under reduced pressure until the water content in the liquid became less than 10%. Finally, MEK was added so that the total amount was 157 g to obtain an amphiphilic dispersion of silver halide grains.

<Preparation of powdered aliphatic carboxylic acid silver salt A>
Aliphatic silver carboxylate particles were prepared using an apparatus as shown in FIG. 1 mol of aliphatic carboxylic acid in tank 21 (composition ratio is shown in Table 4) and 5 mol / L potassium hydroxide aqueous solution while stirring 90% of pure water amount adjusted to concentration 5% at 85 ° C 1,036 ml was added over 5 minutes and then reacted for 60 minutes to obtain an aqueous potassium aliphatic carboxylate solution. Finally, additional pure was added so that the concentration of the aqueous potassium aliphatic carboxylate solution was 5%. Further, 38,300 g of a 5% aqueous solution of silver nitrate was prepared in the tank 22 and kept at 10 ° C. The total amount of the aliphatic potassium carboxylate aqueous solution and silver nitrate aqueous solution was simultaneously added to the mixing device 24 over 4 minutes at a constant addition rate, and stocked in the tank 26. During the addition, the tank 26 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, 27 is a flow meter and 28 is a pump.

<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 / s. The solid content concentration of the obtained aliphatic carboxylic acid silver salt dispersion emulsion was about 27%.

  In the case of the aliphatic carboxylic acid silver salt A in which no photosensitive silver halide emulsion is used 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.

<Coating of photosensitive layer, surface protective layer, and back layer>
A surface protective layer is applied on the undercoat of the undercoated support on the photosensitive layer side with the numerical values described in Table 4 and a surface protective layer is applied thereon so that the dry film thickness is 3.0 μm. did. Subsequently, the back layer was applied on the opposite back layer surface side undercoat so that the dry film thickness was 3.0 μm.

  The drying was performed at 60 ° C. for 15 minutes. While carrying the sample coated on both sides, heat treatment was carried out at 79 ° C. for 10 minutes to obtain photothermographic materials 301 to 312.

<Preparation of photosensitive layer coating solution>
The same amount of MEK is added to 1,670 g of the aliphatic carboxylic acid silver salt dispersion emulsion, and the mixture is kept at 18 ° C. with stirring, and 1.2 g of bis (dimethylacetamide) dibromobromate (11% methanol solution) is added. And stirred for 1 hour. Subsequently, 15.1 g of calcium bromide (11% methanol solution) was added and stirred for 30 minutes. Further, the following 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 (Tg = 75 ° C .: acetal ratio: acetoacetal / butyl acetal = 75 ° C. (3/7)) 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
YA-1 1.4g
CLB-1 0.6g
Antifoggant solution below Developer solution below <Preparation of infrared sensitizing dye solution>
1. Infrared sensitizing dye 1 (supra) 400 mg, infrared sensitizing dye 3 400 mg, 5-methyl-2-mercaptobenzimidazole 130 mg, 2-chloro-benzoic acid 21.5 g, sensitizing dye solubilizer 5 g was dissolved in 135 g of MEK to prepare an infrared sensitizing dye solution.

<Preparation of developer solution>
Reducing agent (type and amount added are listed in Table 4), silver saving agent SE1-4 is 0.0002 mol, l, 4-methylphthalic acid 9 g, dye-A 0.7 g is dissolved in MEK and finished to 800 g. A developer solution was obtained.

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

(Surface protective layer coating solution)
MEK 1056g
148 g of cellulose acetate propionate (Eastman Chemical Co., Ltd .: CAP141-20)
6 g of polymethyl methacrylate (Rohm and Haas, Paraloid A21)
170 g of mat dispersion (silica having an average particle size of 4 μm with a dispersion degree of 10%, solid content concentration of 1.7%)
Crosslinking agent (CH ₂ ═CHSO ₂ CH ₂ ) ₂ CH (OH) 3.6 g
Benzotriazole 2.0g
Fluorine-based surfactant C ₉ F ₁₇ O (CH ₂ CH ₂ O) ₂₃ C ₉ F ₁₇ 5.4 g
Fluorine-based surfactant LiO ₃ S (CF ₂ ) ₃ SO ₃ Li 0.12 g
(Back 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-based acrylic copolymer (Daikin Kogyo Co., Ltd .: Optoflon FM450) 1.21 g
Amorphous saturated copolyester (Toyobo Co., Ltd .: Byron 240P) 18.1 g
Ethylenediamine bis stearamide 2.0g
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

(Sample evaluation)
<Exposure and development processing>
The photothermographic material samples 301 to 312 produced as described above were processed into half-cut sizes (34.5 cm × 43.0 cm), and then exposed in the same manner as in Example 1 using the heat development apparatus shown in FIG. And development processing was performed. However, in place of the 810 nm semiconductor laser as an exposure source, a 786 nm semiconductor laser having a maximum output of 50 mW was used.

(Packaging material)
The same material as in Example 1 was used.

<Performance evaluation>
The following performance was evaluated for each heat-developed image.

<< Image density Dmax >>
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

"Fog Dmin"
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

《Gamma value》
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

《Sharpness》
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

《Density unevenness during heat development》
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

《Light irradiation image storage stability》
Evaluation similar to Example 1 was performed and the results are shown in Table 4.

  In sample 301, when a paper tray with a raised paper tray and a silica gel sealed in the space formed at the bottom of the tray was used, the density fluctuation due to humidity fluctuation was 0.0, and the improvement effect was recognized. It was.

It is a side view which shows roughly the principal part of a heat development apparatus. It is a figure which shows roughly the fatty-acid silver salt manufacturing apparatus based on this invention.

Explanation of symbols

21, 22, 23, 26 Tank 24, 25 Mixing device 27 Flow meter 28 Pump 40 Heat developing device 40a Device housing 45 Sheet photosensitive material storage portion 46 Pickup roller 47 Conveying roller pair 48 Curved guide 49a, 49b Conveying roller 50 Temperature rise Part 51 First heating zone 51a Opposing roller 51b Heating guide 51c Heating heater 51d Fixed guide surface 52 Second heating zone 52a Opposing roller 52b Heating guide 52c Heating heater 52d Fixed guide surface 53 Insulating part 53a Guide part 53b Heating guide 53c Heating Heater 53d Fixed guide surface 54 Cooling section 54a Opposing roller 54b Cooling plate 54c Cooling guide surface 55 Optical scanning exposure section 56 Densitometer 57 Conveying roller pair 58 Sheet photosensitive material placement section 59 Substrate section F Sheet photosensitive material d Gap

Claims (13)

It has a photosensitive layer containing an organic silver salt, silver halide grains, a binder and a reducing agent on the same side of the support, and the dry thickness of the photosensitive layer is 8.0 μm to 16.0 μm. The average gradation (γ value) of the photographic characteristic curve at an optical density of 1.2 is 4.1 to 6.0, and the reducing agent is a compound represented by the following general formula (RD1) Silver salt photothermographic dry imaging material.

[Wherein, X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ₂ represents an alkyl group, which may be the same or different, but at least one is a secondary or tertiary alkyl group. R ₃ represents a hydrogen atom or a group that can be substituted on a benzene ring. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ] R _{3 of the} compound represented by the general formula (RD1) may form a hydroxyl group by deprotecting at least one group having 1 to 20 carbon atoms having a hydroxyl group as a substituent. The silver salt photothermographic dry imaging material according to claim 1, wherein the silver salt photothermographic dry imaging material is a C 1-20 alkyl group having a group as a substituent. The silver salt photothermographic dry imaging material according to claim 1, wherein the photosensitive layer contains a silver saving agent. The silver salt photothermographic dry imaging material according to any one of claims 1 to 3, wherein the maximum value of the image density after heat development is 3.8 or more and 5.0 or less. 5. The silver salt photothermographic dry imaging material according to claim 1, wherein the dry thickness of the photosensitive layer is from 9.0 μm to 15.0 μm. The silver salt photothermographic dry imaging material according to any one of claims 1 to 5, wherein the average gradation (γ value) is 4.5 to 5.5. 7. The silver according to claim 1, wherein the silver halide grains contained in the photosensitive layer contain silver iodide in a proportion of 5 mol% to 100 mol%. Salt photothermographic dry imaging material. A sheet photosensitive material produced by cutting the silver salt photothermographic dry imaging material according to any one of claims 1 to 7 into a sheet shape. An image forming method, wherein the sheet photosensitive material according to claim 8 is conveyed while being heated at a conveying speed of 30 to 200 mm / sec. 9. An image forming method according to claim 8, wherein a part of one sheet of the sheet photosensitive material according to claim 8 is exposed, and development is started at a part of the sheet photosensitive material that has already been exposed. 9. An image forming method, wherein the sheet photosensitive material according to claim 8 is developed by a laser imager in which a distance between an exposure part and a development part is 0 cm or more and 50 cm or less. An image forming method, wherein the sheet photosensitive material according to claim 8 is thermally developed with a laser imager for a heating time of 1 second to 10 seconds. Image forming method characterized by footprint the photothermographic sheet material according to claim 8 is thermally developed by the laser imager is 0.25 m ² or more 0.40 m ² or less.

Images