JP2006350000A - Silver salt photothermographic dry imaging material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material which exhibits high sensitivity, low fog and high maximum density and excels in silver tone and density unevenness in heat development even when rapidly heat-developed with a small laser imager, and to provide 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 side of a support, wherein the photosensitive layer has a dry thickness of 4-16 μm and at least one of constituent layers on the photosensitive layer side of the support contains a compound which develops a color in heat development and forms a dye image, wherein a maximum absorption wavelength of the dye image is 600-700 nm. The image forming method is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a silver salt photothermographic dry imaging material (photothermographic dry imaging material, photothermographic material, photothermographic material, simply thermal development) containing an organic silver salt, silver halide grains, a binder and a reducing agent on a support. And an image forming method.

  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.

  The photothermographic dry imaging material itself has 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 laser imager which forms an image by applying stable heat to the material. As described above, with the rapid spread in recent years, a large amount of this laser imager has been supplied to the market. In recent years, there has been a demand for a compact laser imager and rapid processing.

  For this purpose, it is essential to improve the characteristics of the photothermographic dry imaging material. 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). On the other hand, in order to increase the covering power by uniformly dispersing fine silver halide grains, a technique using organic silver salt grains having a small average particle diameter has been disclosed (for example, see Patent Document 8).

  In order to increase the covering power, it is effective to reduce the developed silver size and increase the number of coloring points, but there is a problem that the color tone is reddish in the high density part, and cyan coloring is developed to improve this point. A technique using a reactive leuco dye has been disclosed (for example, see Patent Document 9). Furthermore, in photothermographic dry imaging materials that use photosensitive silver halide grains, the silver halide grains remain in the photosensitive layer even after thermal development. There has been a problem that deterioration in storage stability when used for diagnosis in a room or when stored in a bright room has been attempted (see, for example, Patent Document 10).

As a response from the apparatus side for downsizing and rapid processing of the laser imager, a technique for shortening the distance of the cooling unit in order to reduce the size of the laser imager (for example, refer to Patent Document 11), 23 mm / second or more. Techniques have been disclosed for performing thermal development while transporting or performing thermal development simultaneously with exposure (see, for example, Patent Documents 12 and 13).
US Pat. No. 3,152,904 US Pat. No. 3,457,075 JP-A-11-295844 JP-A-11-352627 JP 2001-209145 A JP 2002-006443 A (Claims) Japanese Patent Laid-Open No. 2003-065558 (Claims) Japanese Patent Laying-Open No. 2005-092189 (Claims) JP 2004-191939 A (Claims) JP 2003-270755 A (Claims) JP 2004-004522 A (Claims) US Patent Application Publication No. 2004/0058281 (Claims) JP 2004-085763 A (Claims)

  The object of the present invention is to achieve high sensitivity, low fog, high maximum density, silver tone, and uneven density during thermal development even when a silver salt photothermographic dry imaging material is rapidly thermally developed by a small laser imager. An object of the present invention is to provide a silver salt photothermographic dry imaging material and an image forming method which are excellent in the above.

  When the above-mentioned known technology is applied to a silver salt photothermographic dry imaging material and a rapid processing is performed by a small laser imager, the density cannot be sufficiently obtained, and the density unevenness at the time of silver tone and heat development is also deteriorated. A problem occurred. As a result of diligent efforts to solve these problems, the present inventors have determined that the dry film thickness of the photosensitive layer is 4 μm or more and 16 μm or less, and that the dye develops color during thermal development and has a maximum absorption wavelength of 600 nm to 700 nm. It has been found that it is essential to simultaneously satisfy that it contains a compound that forms an image. The above object of the present invention is achieved by the following configurations.

(Claim 1)
Having a photosensitive layer containing an organic silver salt, silver halide grains, a binder, and a reducing agent on the same side of the support, the dry thickness of the photosensitive layer being 4 μm or more and 16 μm or less, and That at least one of the constituent layers on the side of the photosensitive layer of the support contains a compound that develops color during heat development to form a dye image, and the maximum absorption wavelength of the dye image is from 600 nm to 700 nm. Silver salt photothermographic dry imaging material.

(Claim 2)
2. The silver salt photothermographic dry imaging material according to claim 1, wherein the dry thickness of the photosensitive layer is 6 μm or more and 14 μm or less.

(Claim 3)
3. The silver salt photothermographic dry imaging material according to claim 1, wherein the compound that develops a color image during the heat development and forms a dye image is a compound represented by the following general formula (CLA).

[Wherein R ₃₁ and R ₃₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, —NHCO—R ₃₀ group (R ₃₀ is an alkyl group, aryl group, heterocyclic group) Or R ₃₁ and R ₃₂ are groups that are linked to each other to form an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, or a heterocyclic ring. A ₃ represents a —NHCO— group, a —CONH— group or a —NHCONH— group, and R ₃₃ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. W ₃ represents a hydrogen atom or —CONH—R ₃₅ group, —CO—R ₃₅ group or —CO—O—R ₃₅ group (R ₃₅ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group). R ₃₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, carbamoyl group, or nitrile group. R ₃₆ represents —CONH—R ₃₇ group, —CO—R ₃₇ group, or —CO—O—R ₃₇ group (R ₃₇ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group) X ₃ Represents a substituted or unsubstituted aryl group or heterocyclic group. ]
(Claim 4)
The silver salt photothermographic dry according to any one of claims 1 to 3, wherein the compound that develops a color image during the heat development and forms a dye image is a compound represented by the following general formula (CLB). Imaging material.

[Wherein R ₄₁ , R ₄₂ , R _4a and R _4b each independently represents a hydrogen atom, aliphatic group, aromatic group, alkoxy group, aryloxy group, acylamino group, sulfonamido group, carbamoyl group, halogen atom. To express. R ₄₃ represents a hydrogen atom, an aliphatic group, an aromatic group, an acyl group, an alkoxycarbonyl group, an aryloxycarboquinyl group, a carbamoyl group, a sulfamoyl group, or a sulfonyl group. X ₄₁ and X ₄₂ represent a substitutable group on the benzene ring. m41 and m42 represent an integer of 0 to 5. When there are a plurality of X ₄₁ and X ₄₂ , each X ₄₁ and X ₄₂ may be the same or different. ]
(Claim 5)
The silver salt photothermographic dry imaging material according to any one of claims 1 to 4, wherein the reducing agent is a compound represented by the following general formula (RD1).

[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. At least one of R ₂ represents a secondary or tertiary alkyl group and may be the same or different. R ₃ represents an optionally substituted alkyl group having 1 to 20 carbon atoms. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
(Claim 6)
The silver salt according to any one of claims 1 to 5, wherein at least one group of R _{3 in} the general formula (RD1) is an alkyl group having 2 to 20 carbon atoms which may be substituted. Photothermographic dry imaging material.

(Claim 7)
At least one group of R _{3 in} the general formula (RD1) is an alkyl group having a hydroxyl group as a substituent, or an alkyl group having a group capable of forming a hydroxyl group by being deprotected as a substituent. The silver salt photothermographic dry imaging material according to any one of claims 1 to 6, wherein

(Claim 8)
The maximum value of the image density obtained when the silver salt photothermographic dry imaging material is exposed to heat and developed under normal practical heat development conditions is 3.8 to 5.0. The silver salt photothermographic dry imaging material according to any one of claims 1 to 7.

(Claim 9)
The silver salt according to any one of claims 1 to 8, wherein the compound that forms a dye image by color development during the heat development has a maximum absorption wavelength of 360 nm or more and 450 nm or less of the dye image to be formed. Photothermographic dry imaging material.

(Claim 10)
After the silver salt photothermographic dry imaging material is exposed for a certain period of time, white light or light in a specific spectral sensitization region is passed through an optical wedge, or the illuminance of the surface of the photosensitive material of the laser light is changed stepwise. For the sensitivity (S ₁ ) obtained based on the characteristic curve obtained when heat development is performed under normal practical heat development conditions, heating is performed under the same conditions as the heat development conditions before exposure, and thereafter The sensitivity (S ₂ ) obtained based on the characteristic curve obtained by exposure under the same exposure conditions as the exposure and thermal development under the same development conditions as the thermal development is 0 or more as a relative ratio (S ₂ / S ₁ ). It is 1/10 or less, The silver salt photothermographic dry imaging material of any one of Claims 1-9 characterized by the above-mentioned.

(Claim 11)
11. 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.

(Claim 12)
The silver salt photothermographic dry imaging material according to any one of claims 1 to 11, comprising a compound represented by the following general formula (SF).
General formula (SF)
(R _f − (L ₁ ) _m1 −) p- (Y) _n1 − (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, m1 and n1 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, m1 and n1 are not 0 at the same time. ]
(Claim 13)
The silver salt photothermographic dry imaging material according to any one of claims 1 to 12, wherein an average particle diameter of silver halide grains contained in the photosensitive layer is 10 to 50 nm.

(Claim 14)
14. A photosensitive layer containing silver halide grains having an average particle size of 55 to 100 nm in addition to silver halide grains having an average particle size of 10 to 50 nm. The silver salt photothermographic dry imaging material according to claim 1.

(Claim 15)
15. The silver halide grain according to claim 1, wherein at least a part of the silver halide grain contained in the photosensitive layer is a silver halide grain chemically sensitized with a chalcogen compound. Silver salt photothermographic dry imaging material.

(Claim 16)
The sheet-like silver salt photothermographic dry imaging material, wherein the silver salt photothermographic dry imaging material according to any one of claims 1 to 15 is in a sheet form.

(Claim 17)
An image forming method comprising conveying the sheet-like silver salt photothermographic dry imaging material according to claim 16 while heating at a conveying speed of 30 to 200 mm / sec.

(Claim 18)
While a part of one sheet-like silver salt photothermographic dry imaging material according to claim 16 is exposed, development is started on a part of the sheet-like silver salt photothermographic dry imaging material that has already been exposed. An image forming method.

(Claim 19)
An image forming method comprising developing the sheet-like silver salt photothermographic dry imaging material according to claim 16 with a laser imager having a distance between an exposure part and a development part of 0 cm or more and 50 cm or less.

(Claim 20)
An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 16 is thermally developed by a laser imager with a heating time of 10 seconds or less.

(Claim 21)
An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 16 is thermally developed with a laser imager having an installation area of 0.40 m ² or less.

  With the above-described configuration of the present invention, even when a laser imager is miniaturized and rapidly heat-developed, a silver-salt photothermographic photograph that has high sensitivity, low fog, high maximum density, silver tone, and excellent density unevenness during heat development. Imaging materials and image forming methods can be provided.

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

(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 silver carboxylates, the silver behenate content is preferably 50 mol% or more, more preferably 80 mol% or more and 99.9 mol% or less, still more preferably 90 mol% or more and 99.99 mol%. It is preferable to use 9 mol% or less of silver behenate.

  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, it is necessary to prepare a higher ratio of potassium salt during preparation of the aliphatic carboxylic acid silver salt as described above, or to disperse the photosensitive emulsion. 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, 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. 2000-7683. No. 2000-72711, No. 2001-163889, No. 2001-163890, No. 2001-163828, No. 2001-33907, No. 2001-188313, No. 2001-83651, Reference can be made to JP-A Nos. 2002-6442, 2002-31870, and 2003-280135.

  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, a photosensitive material can be produced 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 can be selected according to the purpose. However, 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%, 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 when forming the grains.

Y ₁ O (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH ₂ O) _p (CH ₂ CH ₂ O) _n Y ₁
In the formula, Y ₁ represents a hydrogen atom, —SO ₃ M, or —CO—B—COOM, and M represents an ammonium substituted with a hydrogen atom, an alkali metal atom, an ammonium group, or an alkyl group having 5 or less carbon atoms. Represents a group, 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 the 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 grain according to the present invention is preferably a silver halide grain whose surface sensitivity is lowered by converting from a surface latent image type to an internal latent image type by heat development. That is, in the exposure before thermal 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, and the exposure after the thermal development process has passed. Then, since many latent images are formed inside the surface of the silver halide grains, the silver halide grains are characterized in that the formation of latent images on the surface is suppressed. It has not been known in the past to use silver halide grains whose latent image forming function greatly changes before and after the heat development processing as a dry imaging material.

  In general, when photosensitive silver halide grains are exposed, the silver halide grains themselves or spectral sensitizing dyes adsorbed on the surface of the photosensitive silver halide grains are photoexcited to freely move electrons. Although generated, these electrons are competitively trapped (captured) by an electron trap (photosensitive center) existing on the surface of the silver halide grain or an electron trap inside the grain. Therefore, if there are more chemical sensitization centers (chemical sensitization nuclei) and dopants effective as electron traps on the surface than the inside of the silver halide grains, a latent image is preferentially formed on the surface and development is possible. It becomes. On the contrary, when there are more chemical sensitization centers (chemical sensitization nuclei) and dopants effective as electron traps in the inside than the silver halide grain surface, a latent image is preferentially formed inside, and the surface Development becomes difficult. In other words, in the former case, the surface sensitivity is higher than in the interior, and in the latter case, it can be said that the surface sensitivity is lower than in the interior (reference: (1) edited by TH James, “The Theory of the Photographic Process”. “Fourth Edition, Macmillan Publishing Co., Ltd. 1977, (2) The Japan Photographic Society,“ Revised Photographic Engineering Basics (Silver Salt Photography) ”, Corona, 1998).

  In the photosensitive silver halide grain according to the present invention, it is preferable in terms of sensitivity and image storage stability to contain a dopant functioning as an electron trapping dopant at least during exposure after heat development. .

  In addition, a dopant that functions as a hole trap during the exposure for image formation before heat development, changes in the heat development process, and functions as an electron trap after heat development, Particularly preferred.

  The electron trapping dopant used here is an element or compound other than silver and halogen constituting silver halide grains, and the dopant itself has a property of trapping (capturing) free electrons, or the dopant is halogen. It is the one in which a site such as an electron trapping lattice defect is generated by being contained in a silver halide grain. For example, a metal ion other than silver or a salt or complex thereof, a chalcogen (oxygen group element) such as sulfur, selenium or tellurium, or an inorganic compound or organic compound containing a nitrogen atom or a metal complex thereof, a rare earth ion or a complex thereof, etc. Can be mentioned.

  Examples of metal ions or salts or complexes thereof include lead ions, bismuth ions, gold ions, etc., or lead bromide, lead nitrate, lead carbonate, lead sulfate, bismuth nitrate, bismuth chloride, bismuth trichloride, bismuth carbonate, sodium bismutate, Examples thereof include chloroauric acid, lead acetate, lead stearate, bismuth acetate and the like.

  As the compound containing chalcogen such as sulfur, selenium, and tellurium, various chalcogen-releasing compounds generally known as chalcogen sensitizers in the photographic industry can be used. Moreover, as an organic substance containing chalcogen or nitrogen, a heterocyclic compound is preferable. For example, imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, Tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzthiazole, indolenine, tetrazaindene, preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole, oxadiazole, quinoline, phthalazine, Naphthyridine, quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, o Sasol, benzimidazole, benzoxazole, benzthiazole, a tetrazaindene.

  The above heterocyclic compound may have a substituent, and the alkyl group, alkenyl group, aryl group, alkoxy group, aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group are preferable as the substituent. Aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, sulfonyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, Sulfo group, carboxyl group, nitro group and heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryloxy group, acyl group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonyl group Amino group, sulfamoyl group, carbamoyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, nitro group, heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryloxy group, acyl group An acylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, a halogen atom, a cyano group, a nitro group, or a heterocyclic group.

  The silver halide grains used in the present invention include groups 6 to 11 in the periodic table so that they function as electron trapping dopants as described above or as hole trapping dopants. Transition metal ions belonging to the above may be contained by chemically adjusting the oxidation state of the metal with a ligand or the like. As the transition metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, and Pt are preferable.

  In the present invention, the above various dopants may be used alone or in combination of two or more of the same or different compounds or complexes. However, at least one kind needs to function as an electron trapping dopant at the time of exposure after thermal development. These dopants may be introduced into the silver halide grains in any chemical form.

  In the present invention, an aspect of doping by using any one of Ir or Cu complex or salt alone is not very preferable.

The preferable content of the dopant is preferably in the range of 1 × 10 ⁻⁹ to 1 × 10 mol and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol with ^respect to 1 mol of silver. Furthermore, 1 * 10 ^{< -6} > ^-1 * 10 ^<-2> mol is preferable.

  However, since the optimum amount depends on the kind of dopant, the grain size and shape of the silver halide grains, and other environmental conditions, it is preferable to examine optimization of the dopant addition conditions according to these conditions.

  In the present invention, the transition metal complex or complex ion is preferably represented by the following general formula.

General formula [ML ₆ ] ^m
In the formula, M represents a transition metal selected from Group 6 to 11 elements in the periodic table, L represents a ligand, and m represents 0,-, 2-, 3-, or 4-. Specific examples of the ligand represented by L include halogen ions (for example, fluorine ion, chlorine ion, bromine ion, iodine ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Each ligand includes nitrosyl, thionitrosyl, and the like, preferably aco, nitrosyl, thionitrosyl, and the like. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

  The compounds providing these metal ions or complex ions are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening In addition, it may be added at any stage before or after chemical sensitization, but it is particularly preferably added at the stage of nucleation, growth and physical ripening, and more preferably at the stage of nucleation and growth, Most preferably, it is added in the latter half of nucleation or immediately after. In addition, it may be divided and added several times, and can be uniformly contained in the silver halide grains. For example, JP-A-63-29603, JP-A-2-306236, 3 As described in JP-A Nos. 167545, 4-76534, 6-110146, 5-273683, etc., the particles can be contained with a distribution.

  These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or the silver salt solution and the halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a method of simultaneous mixing of three liquids, a method of introducing an aqueous solution of a required amount of a metal compound into a reaction vessel during grain formation, or a silver halide preparation There is a method of adding and dissolving another silver halide grain that has been previously doped with metal ions or complex ions. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution. When added to the particle surface, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or after physical ripening, or at the time of chemical ripening.

  In addition, a nonmetallic dopant can also be introduce | transduced inside a silver halide by the method similar to said metallic dopant.

  In the imaging material according to the present invention, whether or not the above dopant has an electron trapping property can be evaluated by a method generally used in the photographic industry as follows. That is, a silver halide emulsion comprising silver halide grains doped with the above-mentioned dopant or a decomposition product thereof in silver halide grains is subjected to a photoconductivity measurement by a microwave photoconductivity measurement method or the like, and the halogenation does not contain a dopant. It can be evaluated by measuring the degree of decrease in photoconduction with a silver grain emulsion as a reference. Alternatively, it can be performed by a comparative experiment of the internal sensitivity and surface sensitivity of the silver halide grains.

  Alternatively, the method of evaluating the effect of the electron trapping dopant after preparing the photothermographic dry imaging material is, for example, by heating the imaging material under the same conditions as normal practical thermal development conditions before exposure, and thereafter For a certain period of time (for example, 30 seconds), white light or light in a specific spectral sensitization region (when spectral sensitization is performed on laser light in a specific wavelength region, light in that wavelength region, for example, infrared light) When spectral sensitization is applied, infrared light or light in the photosensitive region unique to silver halide grains, for example, blue light when sensitized to blue light) is exposed through an optical wedge. Alternatively, the sensitivity obtained on the basis of a characteristic curve (sensitometry curve) obtained by performing exposure by changing the illuminance of the photosensitive material surface of the laser beam stepwise and further performing thermal development under the same thermal development conditions as described above. Electron trapping Panto can be evaluated by comparing the sensitivity of the imaging material using the silver halide grain emulsion containing no. That is, it can be confirmed by confirming that the sensitivity of the former sample containing the silver halide grain emulsion containing the dopant according to the present invention is lower than the sensitivity of the latter sample not containing the dopant.

In addition, after exposing the material for a certain period of time by white light or light in a specific spectral sensitization region through an optical wedge, or by changing the illuminance of the photosensitive material surface of the laser light stepwise, a normal practical use For the sensitivity (S ₁ ) obtained based on the characteristic curve obtained when thermal development is performed under the thermal thermal development conditions, heating is performed under the same conditions as the thermal development conditions before exposure, and then the same as the exposure described above. The sensitivity (S ₂ ) obtained on the basis of a characteristic curve obtained by exposure under exposure conditions and heat development under the same development conditions as the above heat development is 1/10 or less as a relative ratio (S ₂ / S ₁ ), preferably Is less than 1/20, and in the case of an imaging material obtained by chemically sensitizing a silver halide grain emulsion, the sensitivity is preferably 1/50 or less. Furthermore, it is most preferable that the surface sensitivity after heat development is substantially zero in both cases where chemical sensitization is not performed and when chemical sensitization is performed.

  Here, the normal heat development condition means that a silver salt photothermographic dry imaging material is heat-developed using a commercially available laser imager in a medical institution such as a hospital, and an image suitable for diagnostic use is obtained. In the case of obtaining, it refers to conditions that are in an appropriate range for conditions such as temperature, development time, and environmental humidity.

  The silver halide grains according to the present invention may be added to the photosensitive layer by any method. For example, the silver halide grains of the present invention, in particular, the heat conversion internal latent image type silver halide grains may be prepared in advance and added to a solution for preparing aliphatic carboxylic acid silver salt grains. The silver halide grain preparation step and the aliphatic carboxylic acid silver salt salt preparation step can be handled separately, which is preferable in terms of production control. Further, it is more preferable to prepare silver halide grains and aliphatic carboxylic acid silver grains of the present invention separately and add them to the photosensitive layer preparation liquid immediately before the coating process.

  Separately prepared photosensitive silver halide grains are freed of unnecessary salts by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, an electrodialysis method, or the like. Although it can be salted, it can also be used without desalting.

  The silver halide grains according to the present invention are used in an amount of 0.001 to 0.7 mol, preferably 0.03 to 0.5 mol, per mol of the aliphatic carboxylic acid silver salt.

(Chemical sensitization)
The photosensitive silver halide grains according to the present invention can be chemically sensitized. For example, use of compounds that release chalcogens such as sulfur, selenium, and tellurium and noble metal ions that release noble metal ions such as gold ions 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 eliminating or reducing the size of silver chalcogenide or silver nuclei on the photosensitive silver halide grains. In particular, it may be preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei. The sensitizing conditions in this case are preferably 6 to 11 as pAg, more preferably 7 to 10, pH 4 to 10, 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 these heterocyclic compounds 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 above basic nucleus. 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 heat development method of the present invention, the sensitizing dye represented by the general formula (1) and the general formula (2) described in US Patent Publication No. 20040224266 are described. It is preferable to select and contain at least one of sensitizing dyes represented by general formula (5), and at least one of the sensitizing dye represented by general formula (5) and the sensitizing dye represented by general formula (6). It is more preferable to select and contain one kind. 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. Examples of supersensitizers include heteroaromatic mercapto represented by the following. 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 by a sensitizing dye, supersensitizer, etc. is the sensitivity when 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. Examples of the reducing agent include compounds represented by the general formula (RD1).

  In the present invention, as the silver ion reducing agent, it is particularly preferable that at least one reducing agent is a compound represented by the general formula (RD1) alone or in combination with a reducing agent having another different chemical structure. .

Among the compounds represented by the general formula (RD1), the use of a compound in which R ₃ is an optionally substituted alkyl group having 2 to 20 carbon atoms is excellent in color tone and density unevenness when rapid processing is performed. This is preferable.

Further, among the compounds represented by the general formula (RD1), an alkyl group in which at least one group of R ₃ has a hydroxyl group as a substituent, or a group capable of forming a hydroxyl group by being deprotected is a substituent. It is more preferable to use a compound having an alkyl group (hereinafter referred to as a compound of (RD1a)) as a photothermographic material having a high concentration and excellent light-irradiated image storage stability. In the present invention, the compound of (RD1a) and the compound of the following general formula (RD2) can be used in combination in order to control the heat development characteristics.

In the formula, 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. Particularly preferred substituents are alkyl groups.

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-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 is most preferable.

R ₃ represents an alkyl group having 1 to 20 carbon atoms, and R ₃ is preferably an alkyl group having 2 to 15 carbon atoms. R ₃ is preferably ethyl, propyl, 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 preferably a hydroxyl group or an alkyl group having 1 to 20 carbon atoms having a group capable of forming a hydroxyl group by deprotection (hereinafter also referred to as a precursor group), preferably a hydroxyl group or a precursor group. It is an alkyl group having 2 to 15 carbon atoms. The alkyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms. 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 group (p-toluenesulfonyloxy group, benzenesulfonyloxy group etc.), carbamoyloxy group (phenylcarbamoyloxy group etc.), thiocarbonyloxy group (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 2 to 5 carbon atoms having a hydroxyl group or a precursor group thereof, such as 2-hydroxyethyl or 3-hydroxypropyl. The most preferred combination of R ₂ and R ₃ is that R ₂ is a tertiary alkyl group (t-butyl, t-amyl group, t-pentyl, 1-methylcyclohexyl, etc.), and R ₃ is a hydroxyl group or a precursor thereof. 1-C20 primary alkyl group having a group (2-hydroxyethyl, 3-hydroxypropyl, etc.). A plurality of R ₂ and R ₃ may be the same or different. Specific examples of the compound represented by the general formula (RD1a) include compounds R-1 to R-20 and R-58 to R-59 described in columns 6 to 16 of US Pat. No. 6,800,431.

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 , R ₇ is the same group as R _3, 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. 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, sulfonamide 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 reducing agents that can be used in combination include US Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, RD17029 and 29963, respectively. 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 the examination based on the expression method based on the hue angle, the color tone after development of the photothermographic material of the present invention is preferably such that the hue angle hab is in the range of 180 ° <hab <270 °, more preferably 200 °. It was found that <hab <270 degrees, most preferably 220 degrees <hab <260 degrees. This is disclosed in Japanese Patent Application Laid-Open No. 2002-6463.

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

However, as a result of further intensive studies on the photothermographic 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 axis as v ^* or b ^* and creating a linear regression line, the linear regression line is specified. By adjusting the range, it was found that it has a diagnostic ability equal to or higher than that of conventional wet silver salt photosensitive materials. A preferable range of conditions is described below.

1. The CIE 1976 (L ^* u ^* v ^* ) color was measured by measuring the optical densities of 0.5, 1.0, 1.5 and the lowest optical density of the silver image obtained after heat development processing of the photothermographic material. The coefficient of determination (multiple determination) R ^{2 of} the linear regression line created by arranging u ^* and v ^* at the respective optical densities on two-dimensional coordinates with the horizontal axis u ^* and the vertical axis v ^* is 0. It is preferable that it is .998 to 1.000.

Furthermore, it is preferable that the v ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (v ^* / u ^* ) is 0.7 to 2.5.

2. In addition, the optical density of the photothermographic material is measured at 0.5, 1.0, 1.5 and the lowest optical density, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space is plotted as a ^*. , vertical axis in the two-dimensional coordinates to b ^*, a ^* in the above each optical density, coefficient of determination of the linear regression line that created arranged b ^* (multiple determination) R ² is at 0.998 to 1.000 Preferably there is.

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

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

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

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

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

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

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

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination of a plurality of types. In 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 to 0.10.

(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).

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

  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.

In the formula, Z represents —S— or —C (R ₂₁ ) (R ₂₁ ′) —, and R ₂₁ and R ₂₁ ′ each represents a hydrogen atom or a substituent.

Examples of 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 by molar ratio, 0.005 More preferably, it is -0.1.

(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 increases when oxidized 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).

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

  The compounds of general formula (CLA) and general formula (CLB) that are preferably used below will be described in detail.

In the general formula (CLA), examples of the halogen atom represented by R ₃₁ and R ₃₂ include a fluorine atom, a bromine atom, and a chlorine atom, and the alkyl group includes an alkyl group having up to 20 carbon atoms (for example, Methyl group, ethyl group, butyl group, dodecyl group and the like, and examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (for example, vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2- A propenyl group, a 3-butenyl group, a 1-methyl-3-propenyl group, a 3-pentenyl group, a 1-methyl-3-butenyl group, and the like. As the alkoxy group, an alkoxy group having up to 20 carbon atoms (for example, methoxy) Group, ethoxy and the like). Examples of the alkyl group represented by R ₃₀ in the —NHCO—R ₃₀ group include alkyl groups having up to 20 carbon atoms (for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, etc.), and an aryl group. Examples thereof include a group having 6 to 20 carbon atoms such as a phenyl group and a naphthyl group, and examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group. The alkyl group represented by R ₃₃ is preferably an alkyl group having up to 20 carbon atoms, and examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group, and the aryl group preferably has 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

In the —CONH—R ₃₅ group, —CO—R ₃₅ group or —CO—O—R ₃₅ group represented by W ₃ , the alkyl group represented by R ₃₅ is preferably an alkyl group having up to 20 carbon atoms. Examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

Examples of the halogen atom represented by R ₃₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include a chain or cyclic alkyl group such as a methyl group, a butyl group, and dodecyl. Group, cyclohexyl group and the like. As the alkenyl group, an alkenyl group having up to 20 carbon atoms (for example, vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl, etc.), and alkoxy groups include, for example, methoxy group, butoxy group, tetradecyloxy group, etc., and carbamoyl Examples of the group include a diethylcarbamoyl group and a phenylcarbamoyl group. Nitrile groups are also preferred. Among these, a hydrogen atom and an alkyl group are more preferable. R ₃₃ and R ₃₄ may be connected to each other to form a ring structure.
The above groups can further have a single substituent or multiple substituents. Typical substituents include halogen atoms (eg, fluorine atom, chlorine atom, bromine atom), alkyl groups (eg, methyl group, ethyl group, propyl group, butyl group, dodecyl group), hydroxyl group, cyano group , Nitro group, alkoxy group (for example, methoxy group, ethoxy group, etc.), alkylsulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, etc.), arylsulfonamide group (for example, phenylsulfonamide group, naphthylsulfone) Amide group etc.), alkylsulfamoyl group (eg butylsulfamoyl group etc.), arylsulfamoyl (eg phenylsulfamoyl group etc.), alkyloxycarbonyl group (eg methoxycarbonyl group etc.), aryl Oxycarbonyl group (for example, phenyloxycarbonyl group, etc.) , Amino sulfonamido group, an acylamino group, a carbamoyl group, a sulfonyl group, a sulfinyl group, a sulfoxy group, a sulfo group, an aryloxy group, an alkoxy group, an alkylcarbonyl group, arylcarbonyl group, and an amino carbonyl group.

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

-CONH-R ₃₇ group represented by R _36, in -CO-R ₃₇ group, or -CO-O-R ₃₇ group, the alkyl group represented by R ₃₇ is preferably an alkyl group having up to 20 carbon atoms Yes, for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, and the like. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, a thienyl group, and the like. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

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

Examples of the aryl group represented by X ₃ include aryl groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, and an imidazole group. Group, pyrazole group, pyrrole group and the like.

Examples of the substituent that the group represented by X ₃ can have include the same substituents as those described in the description of R _{31 to} R _{34 in} formula (CLA).
The group represented by X ₃ is preferably an aryl group or heterocyclic group having an alkylamino group (such as a diethylamino group) at the para position.

  These groups may include photographically useful groups.

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

In the general formula (CLB), specific examples of the aliphatic group represented by R ₄₁ , R ₄₂ , R _4a, and R _4b include hydrocarbon groups such as an alkyl group, an alkenyl group, and an alkynyl group. These hydrocarbon groups preferably have 1 to 25 carbon atoms, and more preferably 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 25 carbon atoms include methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl, cyclohexyl and the like. Examples of the cycloalkyl group include cyclohexyl and cyclopentyl groups. Ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl and the like) and alkynyl groups (ethynyl, 1propynyl, propargyl and the like).

Specific examples of the aromatic group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include aryl groups (phenyl, naphthyl, etc.), heterocyclic groups (pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl). , Pyrimidinyl, pyridazinyl, selenazolyl, sriphoranyl, piperidinyl, pyrazolyl, tetrazolyl and the like.

Specific examples of the alkoxy group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include methoxy group, ethoxy group, isopropyloxy group, tert-butoxy group and the like.

Specific examples of the aryloxy group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include a phenoxy group and a naphthyloxy group.

Examples of the acylamino group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include an acetylamino group and a benzoylamino group.

Specific examples of the sulfonamide group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include a methanesulfonamide group, a butanesulfonamide group, an octanesulfonamide group, a benzenesulfonamide group, and the like.

Examples of the carbamoyl group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include an aminocarbonyl group, a methylaminocarbonyl group, a dimethylaminocarbonyl group, a propylaminocarbonyl group, a pentylaminocarbonyl group, and a cyclohexylaminocarbonyl group. , Phenylaminocarbonyl group, 2-pyridylaminocarbonyl group and the like.

Examples of the halogen atom represented by R ₄₁ , R ₄₂ , R _4a and R _4b are chlorine, bromine and iodine.

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

R _4a and R _4b are preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom.

Examples of the aliphatic group, aromatic group, alkoxy group and aryloxy group represented by R ₄₃ include those of the aliphatic group, aromatic group, alkoxy group and aryloxy group represented by R ₄₁ and R ₄₂ . The example given as a specific example is given.

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

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

Specific examples of the aryloxycarboquinyl group represented by R ₄₃ include a phenoxycarbonyl group.

Examples of the carbamoyl group represented by R ₄₃ include an aminocarbonyl group, a methylaminocarbonyl group, a dimethylaminocarbonyl group, a propylaminocarbonyl group, a pentylaminocarbonyl group, a cyclohexylaminocarbonyl group, a phenylaminocarbonyl group, and 2-pyridylamino. A carbonyl group etc. are mentioned.

Examples of the sulfamoyl group represented by R ₄₃ include methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl and the like.

Examples of the sulfonyl group represented by R ₄₃ include a methylsulfonyl group, a butylsulfonyl group, and an octylsulfonyl group.

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

Specific examples of the group that can be substituted on the benzene ring represented by X ₄₁ and X ₄₂ include alkyl groups having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, Pentyl group, hexyl group, cyclohexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkenyl group (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl- 3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, etc.), alkynyl group (ethynyl, propargyl group, etc.), glycidyl group, acrylate group, methacrylate group, aryl group (phenyl group etc.), aryl group (phenyl, Naphthyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imida Ryl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, triphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.), halogen atom (chlorine atom, bromine atom, iodine atom, fluorine atom, etc.) ), Alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group, etc.), alkoxycarbonyl group (methyloxycarbonyl group) , Ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexane) Sulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl) Group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group, 2-pyridylureido group, etc.), acyl group (acetyl group, propionyl group, Butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Rubonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamide group, propionamide group, butanamide group, hexanamide group, benzamide group) Etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), sulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, Phenylsulfonamide group, naphthylsulfonamide group, etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyri Arylamino group), a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, can be exemplified Okizamoiru group. Further, these groups may be further substituted with these groups.

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

In the above general formula (CLB), R _4a and R _4b are hydrogen atoms, and X ₄₁ and X ₄₂ are each an aliphatic group, aromatic group, amino group, alkoxy group, aryloxy group or dialkylamide at the p-position. Those substituted with a group are preferred.

  The compound represented by the general formula (CLB) can be easily synthesized by a conventionally known method, for example, the method described in Japanese Patent Publication No. 7-45477.

  Next, although the specific example of a compound of general formula (CLB) is shown, this invention is not limited to these.

  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 may be contained in the photosensitive material.

  The compounds of general formulas (RD1), (RD2), general formulas (YA), (YB) and cyan color-forming leuco dyes 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. Yes, natural polymers, synthetic polymers, copolymers, and other media for forming a film, for example, those described in paragraph “0069” of JP-A No. 2001-330918 are exemplified.

  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.

  Among these, particularly preferable examples include alkyl methacrylates, aryl methacrylates, styrenes, and the like. Among such polymer compounds, a polymer compound having an acetal group is preferably used. Even a polymer 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 “0150” 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 the polymer of the present invention is soluble. 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 is also called a plasticizer and 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 Kobunshi 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 as a blend of two or more as necessary. 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 isocyanate may be placed in any part of the photothermographic material. For example, in the support (especially when the support is paper, it can be included in the size composition) photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer and can be added to one or more of these layers.

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

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

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

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

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

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

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

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

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

  Specific examples 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.

  Particularly preferred silver saving agents of the present invention are compounds represented by the following general formulas (SE1) and (SE2).

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

In the general formula (SE1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, thiophene ring, etc. are preferable, and these Also preferred are fused rings in which the rings are fused together.

  These rings may have a substituent, and when they have two or more substituents, these substituents may be the same or different. Examples of substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, arylsulfonamido groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, carbamoyl groups, sulfamoyl groups, cyano Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have substituents. Examples of preferred substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, aryls. Sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, and acyloxy group Can be mentioned.

The carbamoyl group represented by Q ₂ is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms. For example, unsubstituted carbamoyl, methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbamoyl N-sec-butylcarbamoyl, N-octylcarbamoyl, N-cyclohexylcarbamoyl, N-tert-butylcarbamoyl, N-dodecylcarbamoyl, N- (3-dodecyloxypropyl) carbamoyl, N-octadecylcarbamoyl, N- {3 -(2,4-tert-pentylphenoxy) propyl} carbamoyl, N- (2-hexyldecyl) carbamoyl, N-phenylcarbamoyl, N- (4-dodecyloxyphenyl) carbamoyl, N- (2-chloro-5 Dodecyloxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl include N- benzylcarbamoyl.

The acyl group represented by Q ₂ is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2 -Hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, 2-hydroxymethylbenzoyl. The alkoxycarbonyl group represented by Q ₂ is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, Examples include dodecyloxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ₂ is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples thereof include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q2 is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, and 3-dodecyl. Examples include oxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, and 4-dodecyloxyphenylsulfonyl.

The sulfamoyl group represented by Q ₂ is preferably a sulfamoyl group having 0 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as an unsubstituted sulfamoyl group, an N-ethylsulfamoyl group, N- (2- Ethylhexyl) sulfamoyl, N-decylsulfamoyl, N-hexadecylsulfamoyl, N- {3- (2-ethylhexyloxy) propyl} sulfamoyl, N- (2-chloro-5-dodecyloxycarbonylphenyl) sulfamoyl, N- (2-tetradecyloxyphenyl) sulfamoyl is mentioned. The group represented by Q ₂ may further have a group exemplified as an example of the substituent of the 5- to 7-membered unsaturated ring represented by Q ₁ at a substitutable position. When it has two or more substituents, these substituents may be the same or different.

Next, a preferable range of the compound represented by formula (SE1) is described. Q ₁ is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, pyrimidine ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring. 1,2,4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, and these rings Is more preferably a ring fused with a benzene ring or an unsaturated heterocycle. Q ₂ is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on a nitrogen atom.

  General formula (SE2)

In General Formula (SE2), R ¹ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ² represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate ester group. R ³ and R ⁴ each represents a group that can be substituted on the benzene ring. R ³ and R ⁴ may be connected to each other to form a condensed ring.

R ¹ is preferably an alkyl group having 1 to 20 carbon atoms (for example, methyl group, ethyl group, isopropyl group, butyl group, tert-octyl group, cyclohexyl group, etc.), acylamino group (for example, acetylamino group, benzoylamino group, Methylureido group, 4-cyanophenylureido group, etc.), carbamoyl group (n-butylcarbamoyl group, N, N-diethylcarbamoyl group, phenylcarbamoyl group, 2-chlorophenylcarbamoyl group, 2,4-dichlorophenylcarbamoyl group, etc.) An acylamino group (including a ureido group and a urethane group) is more preferable. R ² is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (for example, methoxy group, butoxy group, n-hexyloxy group, n-decyloxy group, cyclohexyloxy group, benzyloxy group, etc.), aryl An oxy group (phenoxy group, naphthoxy group, etc.).

R ³ is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, and most preferably a halogen atom. R ⁴ is preferably a hydrogen atom, an alkyl group, or an acylamino group, and more preferably an alkyl group or an acylamino group. Examples of these preferable substituents are the same as those for R ¹ . When R ⁴ is an acylamino group, R ⁴ is preferably linked to R ³ to form a carbostyryl ring.

In the general formula (SE2), when R ³ and R ⁴ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. The same substituent as the example of the substituent mentioned in the general formula (SE1) may be bonded to the naphthalene ring. When general formula (SE2) is a naphthol compound, R ¹ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ² is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

  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 defined as a material in which the thermal solvent-containing photothermographic dry imaging material can lower the thermal development temperature by 1 ° C. or more as compared with a silver salt photothermographic dry imaging material that does not contain a thermal solvent. More preferably, the material can lower the heat development temperature by 2 ° C. or more, and particularly preferably the material that can lower the temperature by 3 ° C. or more. For example, with respect to the photothermographic dry imaging material A containing a thermosolvent, when the photothermographic dry imaging material A from the photothermographic dry imaging material A is B, the photothermographic dry imaging material B is exposed and thermally developed. When the thermal development temperature for obtaining the density obtained by processing at a temperature of 120 ° C. and a thermal development time of 20 seconds with the photothermographic dry imaging material A at the same exposure amount and thermal development time is 119 ° C. or less, To do.

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

General formula (TS)
(Y ₂ ) _n Z
In General Formula (TS), Y ₂ 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 ₂ may be the same or different.

Y ₂ may further have a substituent, and may have a group represented by Z as a substituent. Y ₂ will be described in more detail. In the general formula (TS), Y ₂ 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, and n-propyl, iso-propyl, sec-butyl, t-butyl, t-octyl, n-amyl, t-amyl, n-dodecyl, n-tridecyl, octadecyl, icosyl, docosyl, cyclopentyl, cyclohexyl, etc.). 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 has 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, and particularly preferably 6 to 25 carbon atoms. Ruphenyl, 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 and pyrrolidyl). Represents.). These substituents may be further substituted with other substituents. These substituents may be bonded to each other to form a ring.

Y ₂ may further have a substituent, and examples of the substituent include the substituent described in “0015” of JP-A No. 2004-21068. The reason why development activity is achieved by using a thermal solvent is that the thermal solvent melts near the development temperature, so that it is compatible with substances involved in development, and a reaction at a lower temperature than when no thermal solvent is added. This is thought to be possible. Since heat development is a reduction reaction involving a carboxylic acid having a relatively high polarity or a silver ion transporter, it is preferable to form a reaction field having an appropriate polarity with a thermal solvent having a polar group. .

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

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

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

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

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

(Anti-fogging 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. Moreover, it is preferable that the compound which can carry out the oxidative bleaching of the silver atom thru | or metal silver (silver cluster) produced at the time of preservation | save of a raw film or an image 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”.

  Examples of the antifoggant preferably used in the present invention include 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-A No. 2000-330235 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 (for example, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide); mercaptans (for example, 3-mercapto-1,2,4-triazole); phthalazinone derivatives or metal salts of these derivatives ( For example, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); phthalazine and phthalic acids ( For example, combinations of phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid; phthalazine and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and 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, the fluorosurfactant represented by the general formula (SF) is preferable in order to improve film transportability and environmental suitability (accumulation in a living body) in a laser imager (heat development processing apparatus). Used.

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

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

(lubricant)
As the lubricant, for example, known lubricants described in paragraphs “0061” to “0064” of JP-A No. 11-84573 can be used, but solid lubricant particles or a lubricant which is liquid at room temperature is used. It is preferable. Examples of the lubricant that is liquid at normal 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.

(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 are, for example, a method of winding with the film edge portion raised, a method of stacking paper between the films, a method of making a frame with cardboard and fixing the four corners, etc. One of them. Examples of the measuring apparatus that can be used include a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO.

  In order to set Rz, Rt, and Ra on the front and back surfaces of the photosensitive material within the scope of the present invention, it 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, average particle size, amount added, 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 during 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 filtration of coating liquid, filtration time 5) Calendar treatment after application Conditions (for example, calendar temperature 40 to 80 ° C., pressure 50 to 300 kg / cm, line speed 20 to 100 m, nip number 2 to 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 it as this range, the transportability of the film is good, and the occurrence of uneven density 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 increase in fog over time is small, the transportability of the film is good, and the occurrence of uneven density during thermal development can be further improved.

  The 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 thermal 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 heat 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.

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

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

  For example, when the silver salt photothermographic dry imaging material of the present invention is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-083655 (this specification) Used as a thiopyrylium squarylium dye) and a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), or a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. It is preferable to do.

  The compound having a squarylium nucleus is a compound having 1-cyclobutene-2-hydroxy-4-one in the molecular structure, and the compound having a croconium nucleus is 1-cyclopentene-2-hydroxy- in the molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Hereinafter, in the present specification, these pigments are collectively referred to as squarylium dyes for convenience. The dyes described in U.S. Pat. No. 5,380,635, JP-A No. 8-201959, JP-A No. 2002-040593, JP-A No. 2003-186135, JP-A No. 2003-195450, US Pat. No. 6,689,547, and US Pat. These compounds can also be preferably used.

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

  In order to improve the charging property, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layer. These may be contained in any layer, but are preferably contained in the backing layer or the surface protective layer on the photosensitive layer side, the undercoat layer and the like. The conductive compounds described in columns 14 to 20 of US Pat. No. 5,244,773 are preferably used. Among these, in the present invention, the surface protective layer on the backing layer side preferably contains a conductive metal oxide. 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. Examples of containing different atoms include, for example, addition of Al, In, etc. to ZnO, addition of Sb, Nb, P, halogen elements, etc. to SnO ₂ , and Nb, Ta to TiO ₂ . 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 the volume resistivity is 10 ⁷ Ω · cm or less, particularly 10 ⁵ Ω · cm or less. These oxides are described in JP-A Nos. 56-143431, 56-120519, 58-62647 and the like. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a conductive material in which the above metal oxide is attached to other crystalline metal oxide particles or fibrous materials (such as titanium oxide) may be used. .

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

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

  As a binder used in these protective layers and backcoat layers, a polymer having a glass transition point (Tg) higher than that of the photosensitive layer and hardly causing scratches or deformation, such as cellulose acetate, cellulose acetate butyrate, and 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, applying a plurality of these coating solutions simultaneously, and then performing a heat treatment. It is preferable. Here, "multiple simultaneous multi-layer coating" means that a coating solution for each constituent layer (for example, a photosensitive layer, a protective layer) is prepared, and each layer is repeatedly coated and dried when it is coated on a support. Instead, it means that each constituent layer can be formed in such a state that a multilayer coating and drying process can be performed simultaneously. That is, the upper layer is provided before the remaining amount of all the solvents in the lower layer reaches 70% by mass or less (more preferably 90% by mass or less).

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

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

In the present invention, the silver coating amount is preferably selected in accordance with the purpose of the silver salt photothermographic dry imaging material, but is 0.3 g / m ² or more for medical purposes. preferably .5g / m ² or less, 0.5 g / m ² or more, 1.5 g / m ² or less is more preferable. Among the applied silver amounts, those derived from silver halide preferably account for 2 to 18%, more preferably 5 to 15%, based on the total silver amount.

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

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

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

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

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

(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 the packaging material for the photothermographic material include, for example, JP-A-8-254793, JP-A-2000-206653, JP-A-2000-235241, JP-A-2002-062625, JP-A-2003-015261, JP 2003-057990 A, JP 2003-084397 A, JP 2003-098648 A, JP 2003-098635 A, JP 2003-107635 A, JP 2003-131337 A, JP 2003-146330 A, Special It is a packaging material described in Japanese Patent Application Laid-Open No. 2003-226439 and Japanese Patent Application Laid-Open No. 2003-228152. The void ratio in the package is 0.01 to 10%, preferably 0.02 to 5%. Nitrogen sealing is performed so that the nitrogen partial pressure in the package is 80% or more, preferably 90% or more. It is good to do. The relative humidity in the package is 10% to 60%, preferably 40% to 55%.

  Further, in the cutting process and the packaging process, in order to prevent image defects such as scratches and white spots, the cleanliness is 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

(Exposure of silver salt photothermographic dry imaging materials)
Regarding the exposure used for the exposure of the silver salt photothermographic dry imaging material of the present invention or the exposure in the image forming method of the present invention, there are various light sources, exposure times, etc. suitable for obtaining a desired appropriate image. The following conditions can be adopted.

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

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

Any light source may be used as long as it is as described above, but it can be preferably achieved by using a laser. As a laser preferably used for the photosensitive material of the present invention, a gas laser (Ar ⁺ , Kr ⁺ , He—Ne), a YAG laser, a dye laser, a semiconductor laser, and the like are preferable. In addition, a semiconductor laser and a second harmonic generation element can be used. Further, a blue to violet light emitting semiconductor laser (such as one having a peak intensity at a wavelength of 350 nm to 440 nm) can be used. An example of a blue to purple light emitting high-power semiconductor laser is Nichia's NLHV 3000E semiconductor laser.

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

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

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

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

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

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

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

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

(Laser imager)
The laser imager (heat development processing apparatus) according to the present invention supplies uniform and stable heat to the entire surface of a film supply unit represented by a film tray, a laser image recording unit, and a silver salt photothermographic dry imaging material. It is composed of a heat-developing device section and a conveying device section for discharging the photothermographic dry imaging material image-formed by heat development from the apparatus through laser recording from the film supply section.

  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 unit is a transport path length in which the photosensitive material is heated to the development temperature in the thermal development apparatus. The path length of the cooling unit is the path length from the heat development unit to the time when the photosensitive material is discharged from the area where the photosensitive material is shielded by the laser imager to the room light where the laser imager is installed. Say.

  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 brought into direct contact with a metal plate, a metal roller, a nonwoven 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 photosensitive material passes after exiting the thermal development section 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, but is usually developed by raising the temperature of the photosensitive material exposed imagewise. 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 30 seconds, more preferably 3 to 15 seconds, and further preferably 3 to 10 seconds. If the heating temperature is less than 80 ° C, a 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 a developing machine. 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 process (the time required for the photosensitive material to be picked up and discharged from the tray portion) is preferably 60 seconds or less, and is preferably 10 seconds or more and 50 seconds or less for emergency diagnosis. Is more preferable.

  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 imaging material is passed between a pressing roller and the plate heater to perform thermal development.

  The linear velocity of the photosensitive material in the exposure section, the heat development section, and the cooling section is arbitrary, but a higher speed is preferable for rapid processing and improvement in throughput. The linear velocity is preferably 25 mm / second or more and 200 mm / second or less, more preferably 28 mm / second or more and 150 mm or less, and still more preferably 30 mm / second or more and 60 mm / second or less. By setting the conveyance speed within this range, density unevenness during heat development can be improved, and the processing time can be shortened.

  A specific example of the laser imager of this aspect is shown in FIG. In order to perform the exposure process and the thermal development process at the same time, that is, in order to start development on a part of the sheet that has already been exposed while exposing a part of the sheet sensitive material, It is preferable that the distance between them is 0 cm or more and 50 cm or less, and this makes a series of processing time of 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 applied to the silver salt photothermographic dry imaging material, and the development part refers to the position where the photothermographic material is heated for the first time for thermal development. Say. In FIG. 1, reference numeral 6 denotes an exposure unit, and a portion where the photosensitive material conveyed from 4 in FIG.

  The heating device, apparatus or means may be a heating means typical as a heat generator using, for example, a hot plate, iron, hot roller, carbon or white titanium. 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. Moreover, it is preferable from the viewpoints 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, 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 12 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 2.0 to 4.0. 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 described above, a photosensitive layer and a 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 4 μm or more and 16 μm or less, preferably 6 μm or more and 14 μm or less, and particularly preferably 8 μm or more and 12 μm or less.

  Another example of the laser imager preferably used in the present invention is a laser imager shown in FIG. As shown in FIG. 2, the thermal development apparatus 40 includes an EC surface in which a photothermographic material is applied on one side of a sheet-like support base made of PET or the like, and a BC side on the side of the support base opposite to the EC side. A latent image is formed on the EC surface with the laser light L from the optical scanning exposure unit 55 while the film F having a sub-scan is conveyed, and then the film F is heated and developed from the BC surface side to visualize the latent image. Then, it is transported upward through the curved transport path and discharged.

  The heat development apparatus 40 in FIG. 2 picks up and conveys a film storage section 45 that is provided near the bottom of the apparatus housing 40a and stores a large number of unused films F, and the uppermost film F in the film storage section 45. A pickup roller 46 for conveying, a conveyance roller pair 47 for conveying the film F from the pickup roller 46, and a curved surface shape for guiding the film F from the conveyance roller pair 47 and conveying the film F in a substantially reversed direction. Laser light L is applied to the film F based on the image data between the curved surface guide 48, the conveyance roller pair 49a, 49b for sub-scanning conveyance of the film F from the curved surface guide 48, and the conveyance roller pair 49a, 49b. An optical scanning exposure unit 55 that forms a latent image on the EC surface by scanning and exposing.

  The thermal developing device 40 further heats the film F on which the latent image is formed from the BC surface side to raise the temperature to a predetermined heat development temperature, and heats the heated film F to a predetermined temperature. A heat retaining section 53 that retains the heat development temperature, a cooling section 54 that cools the heated film F from the BC surface side, a densitometer 56 that is disposed on the outlet side of the cooling section 54 and measures the density of the film F, A transport roller pair 57 that discharges the film F from the densitometer 56, and a film mounting portion that is provided on the upper surface of the apparatus housing 40a so that the film F discharged by the transport roller pair 57 is mounted. 58.

  As shown in FIG. 2, in the thermal development device 40, the film storage unit 45, the substrate unit 59, the transport roller pairs 49 a and 49 b, the temperature raising unit 50, and the heat retaining unit 53 (upstream) are directed upward from the bottom of the apparatus housing 40 a. The film storage portion 45 is at the lowermost position, and the substrate portion 59 is provided between the temperature raising portion 50 and the heat retaining portion 53, so that it is not easily affected by heat.

  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 front end of the film F is exposed while the light F is exposed to the film F by the optical scanning exposure unit 55. On the side, heat development heating is performed by the temperature raising unit 50 and the heat retaining unit 53.

  The temperature raising part 50 and the heat retaining part 53 constitute a heating part, and the film F is heated to the heat development temperature and maintained at the heat development temperature. The temperature raising unit 50 includes a first heating zone 51 that heats the film F on the upstream side, and a second heating zone 52 that heats the film 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 rollers 51a made of silicon rubber or the like, which is arranged so as to maintain a gap narrower than the film thickness so that the film can be pressed against the fixed guide surface 51d of the guide 51b and whose surface is thermally insulating compared to metal or the like; Have

  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 rollers 52a made of silicon rubber or the like, which is arranged to maintain a gap narrower than the film thickness so that the film can be pressed against the fixed guide surface 52d of the guide 52b, and whose surface is more thermally insulating than metal or the like; Have

  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 film F conveyed by the conveying roller pairs 49a and 49b from the upstream side of the temperature raising unit 50 is pressed against the fixed guide surface 51d by each counter roller 51a that is rotationally driven. As a result, 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 BC surface is fixed to the fixed guide surface 51d by pressing the film F conveyed from the first heating zone 51 against the fixed guide surface 52d by each counter roller 52a that is rotationally driven. It is conveyed while being in close contact with and heated.

  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 portion 53, the film F conveyed from the second heating zone 52 is heated (heat retained) 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 portion 53a. However, it passes through the gap d by the conveying force of the opposing roller 52a on the second heating zone 52 side. At this time, the film 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 film F conveyed in the substantially vertical direction from the heat retaining unit 53 is cooled by being brought into contact with the cooling guide surface 54c of the cooling plate 54b made of a metal material or the like by the opposing roller 54a and cooling from the vertical direction. The direction of the film F is changed to the film mounting part 58 in the direction and conveyed. 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 film 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 film placement unit 58. The film placing unit 58 can temporarily place a plurality of films F.

  As described above, in the heat development apparatus 40 of FIG. 2, the film F has the BC surface facing the fixed guide surfaces 51d, 52d, 53d in the heating portion 50 and the heat retaining portion 53, and the photothermographic material. The coated EC surface is conveyed in an open state. In the cooling unit 54, the film F is conveyed with the BC surface contacting the cooling guide surface 54c and cooled, and the EC surface coated with the heat developing material is opened.

  Moreover, the film F is conveyed by the opposing rollers 51a and 52a so that the passage time of the temperature raising part 50 and the heat retaining part 53 is 10 seconds or less. Therefore, the heating time for temperature rise / heat retention is also 10 seconds or less.

  As described above, according to the heat development apparatus 40 of FIG. 2, in the temperature raising unit 50 that requires uniform heat transfer, the heating guides 51b and 52b and the plurality of opposed rollers that press the film F against the heating guides 51b and 52b. Since the film F is conveyed while ensuring contact heat transfer by bringing the film F into close contact with the fixed guide surfaces 51d and 52d by 51a and 52a, the entire surface of the film is heated uniformly and the temperature rises uniformly. Becomes a high-quality image with reduced density unevenness.

  In addition, after the temperature is raised to the heat development temperature, the film is conveyed 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 without being brought into close contact with the fixed guide surface 53d. Even if heating is performed in the gap d (direct heat contact with the fixed guide surface 53d and / or heat transfer by contact with high temperature air around the film), the film temperature is predetermined with respect to the developing temperature (for example, 123 ° C). Within the range of (for example, 0.5 ° C.). Thus, regardless of whether the film is conveyed along the wall surface of the heating guide 53b or the curved surface guide 53a in the gap d, the film temperature difference is less than 0.5 ° C., and a uniform heat retaining state can be maintained. There is almost no risk of density unevenness in the finished film. 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 film F can be 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 in the middle and extends in the vertical direction. Since the film F is discharged to the film mounting unit 58 with the direction of the film F being substantially reversed by the cooling unit 54, the cooling unit 54 has a predetermined curvature according to the apparatus layout. It is possible to cope with downsizing of the installation area and downsizing of the entire device.

  In conventional large machines, the film was heated to the developing temperature and the heat-retaining function after the temperature was raised had the same heating and transport mechanism as the temperature-raising part. As a result, unnecessary parts were used. However, the increase in the number of parts and the cost increase, and in the conventional small machine, it is difficult to guarantee heat transfer at the time of temperature rise, so there is a problem of uneven density, and it is difficult to guarantee high image quality. According to the second embodiment, as in the first embodiment, the thermal development process is performed separately in the temperature raising unit 50 and the heat retaining unit 53, thereby eliminating all of these problems. Can do.

  In addition, the film F is heated from the BC side with the temperature raising unit 50 and the heat retaining unit 53 with the EC surface coated with the photothermographic material open, so that the thermal development process can be performed in a rapid process of 10 seconds or less. When performing, since the solvent (moisture, organic solvent, etc.) contained in the film F to be heated and volatilized (evaporated) is dispersed at the shortest distance by opening the EC surface side, the heating time (volatilization time) is short. However, even if there is a part where the contact between the film F and the fixed guide surfaces 51d and 52d is partially poor, the thermal diffusion effect by the PET base on the BC surface causes a contact property. The temperature difference from the good portion is relaxed, 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, the EC surface side heating was considered to be better. However, the thermal conductivity of PET of the support base of the film F was 0.17 W / m ° C., and the PET base thickness was 170 μm. Considering the fact that it is before and after, it is preferable that the time delay is slight and can be easily offset by increasing the heater capacity, etc., and the effect of reducing the contact unevenness can be expected.

  Further, the solvent (water, organic solvent, etc.) in the film F is going to volatilize (evaporate) while leaving the heat retaining part 53 and reaching the cooling part 54, but the cooling part 54 also has the film F Since the EC surface 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.

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

Example 1
<< Preparation of undercoated photographic support >>
A corona of 8 W · min / m ² on both sides of a biaxially stretched heat-fixed polyethylene terephthalate film having an optical density of 0.150 (measured with a Densitometer PDA-65 manufactured by Konica Corporation) and colored with the following blue dye. The photographic support subjected to the discharge treatment 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 for 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) 15g
(Manufactured by Eastman Chemical: CAP482-20)
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)
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) 10ml
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 the 1/4 amount 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 a lapse of 6 minutes, 3/4 amount of the solution (B1) and the whole 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 was 1161 g per mole of silver to obtain photosensitive silver halide grain emulsion A.

  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 A>
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., a photosensitive silver halide grain emulsion (type and amount added are listed in Table 2) 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 A 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 Got. In addition, the infrared moisture meter was used for the moisture content measurement of an organic silver salt composition.

<Preparation of preliminary dispersion A>
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 —SO ₃ K group of 0.2 mmol / g) was dissolved in 1457 g of MEK, and VMA-GETZMANN Preliminary dispersion A was prepared by gradually adding and thoroughly mixing the above-mentioned powdered organic silver salt A500 g while stirring with a dissolver DISPERMAT CA-40M type.

<Preparation of photosensitive emulsion dispersion 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 1.5 minutes using a pump. A photosensitive emulsion dispersion A was prepared by supplying to SL-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 compound YA-1 of general formula (YB), 0.159 g of cyan chromogenic leuco dye (compound described in Table 2), 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>
1.56 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>
The silver saving agent (SE1-1) 0.05g was melt | dissolved in MEK39.95g, and it was set as the addition liquid 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 maintaining the temperature at 13 ° C., 0.5 g of additive d, 0.5 g of additive e, 0.5 g of additive f, and 13.31 g of binder used in the preliminary dispersion A were added and stirred for 30 minutes. Thereafter, 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 3.5 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, photosensitive material samples 101 to 125 shown in Table 2 were prepared. Coating is the dry film thickness of the photosensitive layer (described in Table 2), and the photosensitive layer protective layer (surface protective layer) is 3.0 μm in dry film thickness (surface protective layer upper layer 1.5 μm, surface protective layer lower layer 1. 5 μm), followed by drying for 10 minutes using drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

  The resulting photothermographic material (Sample 122) has a film surface pH of 5.3 on the photosensitive layer side and a Beck smoothness of 6000 seconds, and a film surface pH on the backcoat layer side of 5.5 and Beck smoothness. Was 9000 seconds. Moreover, when the surface roughness was measured about the samples 101-125, they were Rz (E) / Rz (B) = 0.40 and Rz (E) = 1.4 μm. Rz (B) was 3.5 μm. Ra (E) was 0.09 μm. Ra (B) was 0.12 μm. Regarding samples 101 to 125, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed. Samples 101 to 111, 114 to 122, and 124 to 125 have an absorption peak at a maximum absorption wavelength of 640 nm due to the cyan chromogenic leuco dye, and samples 112 to 113 have an absorption peak at a maximum absorption wavelength of 620 nm due to the cyan chromogenic leuco dye. Admitted.

  For sample 119, in the preparation of powdered organic silver salt A in sample 102, instead of 130.8 g behenic acid, 67.7 g arachidic acid, 43.6 g stearic acid, and 2.3 g palmitic acid, 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 120 is 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 is changed from SF-17 to C ₈ F ₁₇ SO ₃ Li. A sample was prepared.

For sample 121, SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing 0.2 mmol / g of SO ₃ K) was used instead of SO ₃ K group-containing polyvinyl butyral as the photosensitive layer binder in the preparation of preliminary dispersion A in sample 102. _A sample was prepared in the same manner as Sample 102 except that ₃ K group-containing polyvinyl butyral (Tg 65 ° C., containing SO ₃ K 0.2 mmol / g) was used.

<Exposure and development processing>
The photothermographic material samples 101 to 125 prepared as described above were processed into half-cut sizes (34.5 cm × 43.0 cm), and then packaged in the following packaging materials in an environment of 25 ° C. and 50% for 2 weeks at room temperature. Following storage, the following evaluations were made.

(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 / atm · m ² · 25 ° C. · day, Water permeability: 0.001 g / m ² · 40 ° C. 90% RH · day barrier bag (according to JIS Z0208 cup method). Use paper tray.

(Sample evaluation)
Evaluation was carried out simultaneously with exposure with the laser imager (installation area 0.35 m ² ) shown in FIG. 1, and the obtained image was evaluated with a densitometer. Here, “thermal development at the same time as exposure” means a sheet photosensitive material made of a silver salt photothermographic dry imaging material, and development is performed on a part of the sheet that has already been exposed while being partially exposed. Means to be started. The distance between the exposed part and the developing part was 12 cm. The ratio of the path length of the cooling section to the path length of the heat development section was 0.8. At this time, the conveyance speed from the photosensitive material supply unit to the image exposure unit, the conveyance rate at the image exposure unit, and the conveyance rate at the thermal development unit were 32 mm / second, respectively, and the time required for the thermal development process (photosensitive The time taken from when the material was picked up at the tray section until it was discharged was 45 seconds. In addition, the position of the bottom surface of the photosensitive material stock tray located at the bottom was 45 cm high from the floor surface. The photothermographic dry imaging material produced as described above is set in the film accommodating portion 4 of the laser imager shown in FIG. 1, and a film guide 10 (only a part of the conveyance roller 2 is set up to the outlet 7 is shown). It is conveyed by. The transported photothermographic dry imaging material is exposed by laser scanning from an exposure unit 6 using an exposure machine using a semiconductor laser having a longitudinal multimode wavelength of 810 nm and high frequency superimposition with a maximum output of 50 mW from the photosensitive surface side as an exposure source. Gave. At this time, an image was formed by setting the angle of the exposure surface of the photothermographic dry imaging material and the exposure laser beam to 75 degrees. In this method, an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 degrees.

  Thereafter, heat development was performed at 123 ° C. for 8 seconds so that the non-photosensitive surface of the photothermographic dry imaging material and the surface of the developing unit 3 were in contact with each other. (In the case of continuous processing, the interval time of heat development is 4 seconds.) The photothermographic dry imaging material subjected to heat development is cooled at the non-photosensitive surface side by the cooling member in the cooling unit 5, but FIG. The roller shape is shown in FIG. 1B. The laser imager was operated in a room conditioned at 23 ° C. and 50% RH.

  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 performance described later for each heat-developed image was evaluated, and the results are shown in Table 2. However, the description place is written together in the place showing the evaluation result of Example 2 described later.

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, 4.5 g of a fluorosurfactant (Asahi Glass Co., Ltd .: Surflon KH40) and 2.3 g of a fluorosurfactant (Dainippon Ink Co., Ltd .: MegaFag F120K) dissolved in 43.2 g of methanol were added to the dissolved solution. Add and stir well 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 of 15% monodispersity (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 the 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 above photosensitive silver halide emulsion C, the same procedure was followed except that 4 ml of a 0.1% ethanol solution of the above compound (TPPS) was added after addition of the entire amount of 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 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 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 A1>
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., a photosensitive silver halide grain emulsion (type and addition amount 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 airflow dryer Flashjet dryer (Seishin). Powdered organic silver salt A1 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 Got.

<Preparation of preliminary dispersion A1>
Although it produced similarly to the preliminary dispersion liquid A in Example 1, instead of the powder organic silver salt A, powder organic silver salt A1 was used.

<Preparation of photosensitive emulsion dispersion A1>
Media type disperser DISPERMAT filled with 80% of the internal volume of 0.5 mm diameter 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 A1 was prepared by supplying to SL-C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

  The stabilizer liquid and additive liquid b are the same liquids as the stabilizer liquid and additive liquid b of Example 1.

<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>
1. Reducing agent (compound described in Table 3 (reducing agent) and amount), 0.159 g of yellow chromophoric leuco dye YA-2, 0.159 g of cyan chromogenic leuco dye (compound described in Table 3), 54 g of 4-methylphthalic acid was dissolved in 110 g of MEK to obtain an additive solution a1.

<Preparation of additive liquid c1>
0.2 g of silver saving agent (SE2-2) was dissolved in 39.8 g of MEK to obtain an additive liquid c1.

<Preparation of additive liquid 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 A1 and 15.11 g of MEK were kept at 21 ° C. with stirring, and 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 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 liquid d1, 0.5 g of additive liquid e1, and 13.31 g of binder used in the preliminary dispersion were added and stirred for 30 minutes, and then tetrachlorophthalic acid (9. (4% MEK solution) 1.084 g was added and stirred for 15 minutes. While further stirring, 12.43 g of additive liquid a1, 1.6 ml of Desmodur N3300 / Moby aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b, 1.0 g of additive liquid c1 A photosensitive layer coating solution was obtained by sequentially adding and stirring.

<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 phthalazine, 3.5 g CH ₂ ═CHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH═CH ₂ , 1 g C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ , 1 g Compound SF-17 represented by the general formula (SF): 10 g of stearic acid and 10 g of butyl stearate were added and dissolved with 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 phthalazine, 3.5 g CH ₂ ═CHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH═CH ₂ , 1 g C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ , 0 0.5 g of the compound SF-17 represented by the general formula (SF), 1.0 g of a fluoropolymer (FM-1: supra), 10 g of stearic acid, 10 g of butyl stearate were added with stirring; 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 3.5 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. The photothermographic material samples 201 to 226 shown in Table 3 were prepared. Coating is the dry film thickness of the photosensitive layer (described in Table 3), and the photosensitive layer protective layer (surface protective layer) is 3.0 μm in dry film thickness (surface protective layer upper layer 1.5 μm, surface protective layer lower layer 1. 5 μm), followed by drying 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 201-226, they were Rz (E) / Rz (B) = 0.40 and Rz (E) = 1.4 μm. Rz (B) was 3.5 μm. Ra (E) was 0.09 μm. Ra (B) was 0.12 μm.

  With respect to Samples 201 to 226, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed. Further, Samples 201 to 212, 215 to 223, and 225 to 226 have an absorption peak at a maximum absorption wavelength of 640 nm due to the cyan coloring leuco dye, and Samples 213 to 214 have an absorption peak at a maximum absorption wavelength of 620 nm due to the cyan coloring leuco dye. Admitted.

  For sample 220, in the preparation of powdered organic silver salt A in sample 203, behenic acid 259. instead of 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. A sample was prepared in the same manner as Sample 203 except that 4 g and arachidic acid 0.5 g were used.

Sample 221 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.

For sample 222, SO ₃ K group-containing polyvinyl butyral (Tg 75 ° C., containing 0.2 mmol / g of SO ₃ K) was used as the photosensitive layer binder in the preparation of preliminary dispersion A in sample 203. _A sample was prepared in the same manner as Sample 203 except that ₃ K group-containing polyvinyl butyral (Tg 65 ° C., containing SO ₃ K 0.2 mmol / g) was used.

(Sample evaluation)
Evaluation was carried out simultaneously with exposure with the laser imager (installation area 0.35 m ² ) shown in FIG. 1, and the obtained image was evaluated with a densitometer. Here, “thermal development at the same time as exposure” means a sheet photosensitive material made of a silver salt photothermographic dry imaging material, and development is performed on a part of the sheet that has already been exposed while being partially exposed. Means to be started. The distance between the exposed part and the developing part was 12 cm. The ratio of the path length of the cooling section to the path length of the heat development section was 0.8. At this time, the conveyance speed from the photosensitive material supply unit to the image exposure unit, the conveyance rate at the image exposure unit, and the conveyance rate at the thermal development unit were 32 mm / second, respectively, and the time required for the thermal development process (photosensitive The time taken from when the material was picked up at the tray section until it was discharged was 45 seconds. In addition, the position of the bottom surface of the photosensitive material stock tray located at the bottom was 45 cm high from the floor surface. The photothermographic dry imaging material produced as described above is set in the film accommodating portion 4 of the laser imager shown in FIG. 1, and a film guide 10 (only a part of the conveyance roller 2 is set up to the outlet 7 is shown). It is conveyed by. The transported photothermographic dry imaging material is exposed from the photosensitive surface side of the exposure unit 6 by an exposure machine using a semiconductor laser (NLHV3000E from Nichia Corporation) with a maximum output of 50 mW and an emission wavelength of 405 nm as an exposure source. Exposure by laser scanning was given. At this time, an image was formed by setting the angle of the exposure surface of the photothermographic dry imaging material and the exposure laser beam to 75 degrees. In this method, an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 degrees.

  Thereafter, heat development was performed at 123 ° C. for 10 seconds so that the non-photosensitive surface of the photothermographic dry imaging material and the surface of the developing unit 3 were in contact with each other. (In the case of continuous processing, the interval time of heat development is 4 seconds.) The photothermographic dry imaging material subjected to heat development is cooled at the non-photosensitive surface side by the cooling member in the cooling unit 5, but FIG. The roller shape is shown in FIG. 1B. The laser imager was operated in a room conditioned at 23 ° C. and 50% RH.

  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.

(Measurement method of cooling rate)
For the measurement of the cooling rate, 10 thermocouples are uniformly attached to the photosensitive surface and the non-photosensitive surface of the photothermographic dry imaging material, and the processes from heat development to cooling and discharging are performed, and each surface becomes 45 ° C. The temperature history up to was measured.

<Packaging materials>
PET 10 μm / PE 12 μm / Aluminum foil 9 μm / Ny 15 μm / Polyethylene 50 μm containing 3% carbon, Oxygen permeability: 0.02 ml / atm · m ² · 25 ° C. · day, Water permeability: 0.001 g / m ² · 40 ° C. 90% RH · day barrier bag (according to JIS Z0208 cup method). Use paper tray.

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

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

"sensitivity"
The image obtained under the above conditions was subjected to density measurement using a densitometer, and a characteristic curve comprising a horizontal axis—exposure amount and a vertical axis—density was created. In the characteristic curve, the sensitivity was defined by defining the reciprocal of the exposure amount giving a density 1.0 higher than that of the unexposed portion as sensitivity. The sensitivity is expressed as a relative value with Sample 1 as 100.

  Note: The values in parentheses in the relative sensitivity column indicate that the photosensitive material is heat-treated at a heat development temperature of 123 ° C. for 10 seconds before being exposed to white light, and then exposed to white light through an optical wedge (4874K, 30 seconds). In comparison between the sensitivity when thermally developed at 123 ° C. for 10 seconds and the sensitivity when thermally developed at 123 ° C. for 10 seconds after exposure to white light under the same conditions as described above without heat treatment before exposure, the latter The sensitivity relative value of the former when the sensitivity is 100 is shown.

  In this relative comparison, the main cause of the decrease in the relative sensitivity of the sample obtained by heat-treating the photosensitive material at the heat development temperature before exposing the photosensitive material to white light is the surface sensitivity of the silver halide grains due to the disappearance or reduction of the spectral sensitization effect. It was confirmed by observation / measurement of changes in the spectral sensitivity spectrum that the relative relationship between the internal sensitivity and the internal sensitivity was changed.

《Silver tone in high density area》
A chest X-ray image was printed on each photothermographic material sample, and the photothermographic treatment was carried out so that the maximum density was 4.0 or more by appropriately adjusting the processing time. The silver color tone in the high density part after treatment (at a density of 2.5) was visually evaluated using a Schaukasten. A wet processed laser imager film manufactured by Konica was used as a standard sample at this time, and the relative color tone with respect to the standard sample was evaluated visually by 0.5 increments according to the following criteria.

5: The same color tone as the standard sample 4: Almost the same preferred color tone as the standard sample 3: Level slightly different from the standard sample, but no practical problem 2: Color tone clearly different from the standard sample 1: Unpleasant color tone different from the standard sample

《Light irradiation image storage stability》
Each photothermographic material sample was exposed and developed in the same manner as described above, and then the change in the image was visually observed after being stuck on a Schaukasten with a luminance of 1000 lux and left for 10 days. Evaluated.

5: Almost no change 4: Slight color change is observed 3: Color change and fog increase are observed in part 2: Color change and fog increase are observed in a considerable part 1: Color change and fog change The increase is remarkable and strong density unevenness occurs on the entire surface.

《Density unevenness during heat development》
The density unevenness after development was evaluated visually by 0.5 increments according to the following criteria.

5: Occurrence 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 Combined results Tables 2 and 3 show the results.

  From Tables 2 and 3, the sample of the present invention, when subjected to high-speed heat development using a compact laser imager, has higher sensitivity, lower fog, and higher maximum density than the comparative sample. It is clear that the light irradiation image storage stability, silver tone, and density unevenness during heat development are excellent.

  Further, comparing Samples 121 and 102, it was found that Sample 102 has superior characteristics with respect to fog rise during high-temperature storage.

  Further, comparing Samples 222 and 203, it was found that Sample 203 has superior characteristics with respect to fog rise during high-temperature storage.

  Moreover, the average gradations of 0.25 to 2.5 in the optical densities of the samples 102, 104, 106, 203, 205, and 207 are all 3.5, and the samples 103, 105, 107, 204, 206, and 208 are samples. The average gradation of 0.25 to 2.5 with an optical density of 3.0 was 3.0, and an image with high diagnostic recognizability was obtained for medical use.

1 is a schematic configuration diagram of a laser imager (thermal development recording apparatus) for thermally developing a silver salt photothermographic dry imaging material according to the present invention to form an image. It is a schematic block diagram of the laser imager (thermal development recording apparatus) of another aspect for thermally developing the silver salt photothermographic dry imaging material which concerns on this invention, and forming an image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film 2 Conveyance roller 3 Developing part 4 Film accommodating part 5 Cooling part 6 Exposure part 7 Exit 10 Film guide 40 Thermal developing apparatus 50 Temperature rising part 51 1st 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 part 54a Opposing roller 54b Cooling plate 54c Cooling guide surface 55 Light Scanning exposure unit 56 Conveying roller pair 40a Device housing 45 Film storage unit 46 Pickup roller 47 Conveying roller pair 48 Curved guide 49a, 49b Conveying roller 56 Densitometer 57 Conveying roller pair 58 Film mounting unit 59 Substrate unit F film, sheet film L laser beam d gap

Claims (21)

Having a photosensitive layer containing an organic silver salt, silver halide grains, a binder, and a reducing agent on the same side of the support, the dry thickness of the photosensitive layer being 4 μm or more and 16 μm or less, and That at least one of the constituent layers on the side of the photosensitive layer of the support contains a compound that develops color during heat development to form a dye image, and the maximum absorption wavelength of the dye image is from 600 nm to 700 nm. Silver salt photothermographic dry imaging material. 2. The silver salt photothermographic dry imaging material according to claim 1, wherein the dry thickness of the photosensitive layer is 6 μm or more and 14 μm or less. 3. The silver salt photothermographic dry imaging material according to claim 1, wherein the compound that develops a color image during the heat development and forms a dye image is a compound represented by the following general formula (CLA).

[Wherein R ₃₁ and R ₃₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, —NHCO—R ₃₀ group (R ₃₀ is an alkyl group, aryl group, heterocyclic group) Or R ₃₁ and R ₃₂ are groups that are linked to each other to form an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, or a heterocyclic ring. A ₃ represents a —NHCO— group, a —CONH— group or a —NHCONH— group, and R ₃₃ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. W ₃ represents a hydrogen atom or —CONH—R ₃₅ group, —CO—R ₃₅ group or —CO—O—R ₃₅ group (R ₃₅ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group). R ₃₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, carbamoyl group, or nitrile group. R ₃₆ represents —CONH—R ₃₇ group, —CO—R ₃₇ group, or —CO—O—R ₃₇ group (R ₃₇ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group) X ₃ Represents a substituted or unsubstituted aryl group or heterocyclic group. ] The silver salt photothermographic dry according to any one of claims 1 to 3, wherein the compound that develops a color image during the heat development and forms a dye image is a compound represented by the following general formula (CLB). Imaging material.

[Wherein R ₄₁ , R ₄₂ , R _4a and R _4b each independently represents a hydrogen atom, aliphatic group, aromatic group, alkoxy group, aryloxy group, acylamino group, sulfonamido group, carbamoyl group, halogen atom. To express. R ₄₃ represents a hydrogen atom, an aliphatic group, an aromatic group, an acyl group, an alkoxycarbonyl group, an aryloxycarboquinyl group, a carbamoyl group, a sulfamoyl group, or a sulfonyl group. X ₄₁ and X ₄₂ represent a substitutable group on the benzene ring. m41 and m42 represent an integer of 0 to 5. When there are a plurality of X ₄₁ and X ₄₂ , each X ₄₁ and X ₄₂ may be the same or different. ] The silver salt photothermographic dry imaging material according to any one of claims 1 to 4, wherein the reducing agent is a compound represented by the following general formula (RD1).

[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. At least one of R ₂ represents a secondary or tertiary alkyl group and may be the same or different. R ₃ represents an optionally substituted alkyl group having 1 to 20 carbon atoms. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ] The silver salt according to any one of claims 1 to 5, wherein at least one group of R _{3 in} the general formula (RD1) is an alkyl group having 2 to 20 carbon atoms which may be substituted. Photothermographic dry imaging material. At least one group of R _{3 in} the general formula (RD1) is an alkyl group having a hydroxyl group as a substituent, or an alkyl group having a group capable of forming a hydroxyl group by being deprotected as a substituent. The silver salt photothermographic dry imaging material according to any one of claims 1 to 6, wherein The maximum value of the image density obtained when the silver salt photothermographic dry imaging material is exposed to heat and developed under normal practical heat development conditions is 3.8 to 5.0. The silver salt photothermographic dry imaging material according to any one of claims 1 to 7. The silver salt according to any one of claims 1 to 8, wherein the compound that forms a dye image by color development during the heat development has a maximum absorption wavelength of 360 nm or more and 450 nm or less of the dye image to be formed. Photothermographic dry imaging material. After the silver salt photothermographic dry imaging material is exposed for a certain period of time, white light or light in a specific spectral sensitization region is passed through an optical wedge, or the illuminance of the surface of the photosensitive material of the laser light is changed stepwise. For the sensitivity (S ₁ ) obtained based on the characteristic curve obtained when heat development is performed under normal practical heat development conditions, heating is performed under the same conditions as the heat development conditions before exposure, and thereafter The sensitivity (S ₂ ) obtained based on the characteristic curve obtained by exposure under the same exposure conditions as the exposure and thermal development under the same development conditions as the thermal development is 0 or more as a relative ratio (S ₂ / S ₁ ). It is 1/10 or less, The silver salt photothermographic dry imaging material of any one of Claims 1-9 characterized by the above-mentioned. 11. 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. The silver salt photothermographic dry imaging material according to any one of claims 1 to 11, comprising a compound represented by the following general formula (SF).
General formula (SF)
(R _f − (L ₁ ) _m1 −) p- (Y) _n1 − (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, m1 and n1 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, m1 and n1 are not 0 at the same time. ] The silver salt photothermographic dry imaging material according to any one of claims 1 to 12, wherein an average particle diameter of silver halide grains contained in the photosensitive layer is 10 to 50 nm. 14. A photosensitive layer containing silver halide grains having an average particle size of 55 to 100 nm in addition to silver halide grains having an average particle size of 10 to 50 nm. The silver salt photothermographic dry imagen material according to claim 1. 15. The silver halide grain according to claim 1, wherein at least a part of the silver halide grain contained in the photosensitive layer is a silver halide grain chemically sensitized with a chalcogen compound. Silver salt photothermographic dry imaging material. The sheet-like silver salt photothermographic dry imaging material, wherein the silver salt photothermographic dry imaging material according to any one of claims 1 to 15 is in a sheet form. An image forming method comprising conveying the sheet-like silver salt photothermographic dry imaging material according to claim 16 while heating at a conveying speed of 30 to 200 mm / sec. While a part of one sheet-like silver salt photothermographic dry imaging material according to claim 16 is exposed, development is started on a part of the sheet-like silver salt photothermographic dry imaging material that has already been exposed. An image forming method. An image forming method comprising developing the sheet-like silver salt photothermographic dry imaging material according to claim 16 with a laser imager having a distance between an exposure part and a development part of 0 cm or more and 50 cm or less. An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 16 is thermally developed by a laser imager with a heating time of 10 seconds or less. An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 16 is thermally developed with a laser imager having an installation area of 0.40 m ² or less.

Images