JP2004094240A - Heat developable photosensitive material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high picture quality equal to or superior to a wet type silver halide photosensitive material, particularly, having an excellent property for image diagnosis, and to provide a method for forming an image. <P>SOLUTION: The optical density of 0.5, 1.0, 1.5 and the minimum optical density of the heat developable photosensitive material are measured, and u<SP>*</SP>and v<SP>*</SP>at each of the above densities are plotted on a a two-dimensional coordinate having the u<SP>*</SP>as the abscissa and the v<SP>*</SP>as the ordinate in the CIE 1976(L<SP>*</SP>u<SP>*</SP>v<SP>*</SP>) color space to produce a linear regression line. The coefficient of major determination R<SP>2</SP>of the linear regression line is ≥0.998 and ≤1.000. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a photothermographic material and an image forming method.

Conventionally, in the fields of medical treatment and printing plate making, the waste liquid due to wet processing of image forming materials has been a problem in terms of workability.In recent years, the amount of treated waste liquid has been strongly reduced from the viewpoint of environmental conservation and space saving. Is desired.

Therefore, there is a need for a technology relating to photothermographic materials for photographic technology, which enables efficient exposure with a laser imager or a laser imagesetter and can form a high-resolution, clear black image.

As such a technique, a photothermographic material (photothermographic material) containing an organic silver salt, photosensitive silver halide particles, and a reducing agent on a support (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1) .)It has been known. Since this photothermographic material does not use any solution processing chemicals, it is possible to provide the user with a system that is simpler and does not damage the environment.

Further improvement in image quality is demanded as a so-called eternal theme of photothermographic materials. In particular, in the field of medical images, there is a demand for higher image quality that enables more accurate diagnosis. It has been pointed out that the heat-developable photosensitive material is inferior in image quality as compared with a wet-type silver halide photosensitive material conventionally used for medical image diagnosis.
U.S. Pat. No. 3,152,904 U.S. Pat. No. 3,487,075 D. H. Klosterboer: Dry Silver Photographic Materials: Handbook of Imaging Materials, Marcel Dekker, Inc. Page 48, 1991

Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat developing method which is equivalent to or higher in image quality than conventional wet-type silver halide photographic materials, and particularly excellent in image diagnostic performance. An object of the present invention is to provide a photosensitive material and an image forming method.

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

1. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was the two-dimensional coordinates to v ^*, and wherein the u ^* at each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998 Photothermographic material.

2. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was the v ^* to the two-dimensional coordinate in terms of the, u ^* of the above each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998, and a vertical axis A photothermographic material, wherein the value of v ^{* at} the intersection of is not less than -5 and not more than 5.

3. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was Is determined by placing u ^* and v ^* at the above respective optical densities in two-dimensional coordinates where v ^* is v ^*, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and the slope (v ^* / U ^* ) is 0.7 or more and 2.5 or less.

4. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was Is determined by arranging a ^* and b ^* at the respective optical densities in two-dimensional coordinates where b ^* is the b ^*, and the determination R ² of the linear regression line created is 0.998 or more and 1.000 or less. Photothermographic material.

5. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was the two-dimensional coordinates to b ^*, a ^* in the above each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998, and a vertical axis A photothermographic material, wherein the b ^* value at the point of intersection is -5 or more and 5 or less.

6. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was the two-dimensional coordinates to b ^*, a ^* in the above each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998, and the slope (b ^* / A ^* ) is 0.7 or more and 2.5 or less.

7. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . the two-dimensional coordinates, the photothermographic material characterized in that the u ^* at each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998 .

8. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . In the two-dimensional coordinates, u ^* and v ^* at the respective optical densities described above are arranged, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and v at the intersection with the vertical axis. ^{* A} photothermographic material having a value of -5 or more and 5 or less.

9. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . the two-dimensional coordinates, u ^* of the above each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998, and the slope (v ^* / u ^* Is 0.7 to 2.5.

10. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . to the two-dimensional coordinates, the photothermographic material characterized in that the a ^* at each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998 .

11. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . In the two-dimensional coordinates, a ^* and b ^* at each of the above optical densities are arranged, and the overlap determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and b at the intersection with the vertical axis ^{* A} photothermographic material having a value of -5 or more and 5 or less.

12. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . In the two-dimensional coordinates, a ^* and b ^* at each of the above optical densities are arranged, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and the slope (b ^* / a ^*) Is 0.7 to 2.5.

{13. 13. The heat as described in any one of the above items 1 to 12, comprising a reducing agent represented by the following general formula (A-1) and a compound represented by the following general formula (A-4). Developed photosensitive material.

(In the formula, Z represents an atomic group necessary for constituting a 3- to 10-membered ring together with a carbon atom, and R _x represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. R ₁ , R ₂ , Q ₀ represents a group substitutable on the benzene ring, L represents a divalent linking group, k is an integer of 0 to 1, n and m represents an integer of 0 to 2. plurality of R _1, R ₂ and Q ₀ may be the same or different.)

(Wherein, R ₄₁ represents a substituted or unsubstituted alkyl group, R ₄₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted acylamino group, and R ₄₁ and R ₄₂ represent 2- not be a hydroxyphenyl methyl group .R ₄₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group, R ₄₄ represents a substituent capable of substituting on the benzene ring.)
14． 15. The photothermographic material as described in 13 or 14, wherein the reducing agent represented by the general formula (A-1) is a reducing agent represented by the following general formula (A-2).

(Wherein, Q ₁ represents a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and Q ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, G represents a nitrogen atom or a carbon atom, and when G is a nitrogen atom, ng is 0. When G is a carbon atom, ng is 0 or 1. Z ₂ is carbon atom. And a group of atoms necessary to form a 3- to 10-membered non-aromatic ring together with the atom and G. R ₁ , R ₂ , R _x , Q ₀ , L, k, n, and m are represented by the general formula ( It is the same as that in A-1).
15. 15. The photothermographic material as described in 13 or 14, wherein the reducing agent represented by the general formula (A-1) is a reducing agent represented by the general formula (A-2).

{16. 16. The photothermographic material according to any one of the above items 13 to 15, wherein the non-aromatic ring represented by Z in the general formula (A-2) has 6 members.

{17. Wherein the layer on the side having the image forming layer of the photothermographic material contains at least one silver saving agent selected from a vinyl compound, a hydrazine derivative, a silane compound and a quaternary onium salt. 17. The photothermographic material according to any one of items 16 to 16.

{18. 18. An image forming method, comprising developing the photothermographic material according to any one of 1 to 17 above at a temperature of 110 ° C. to 140 ° C. for a time of 5 seconds to 20 seconds to form an image.

{19. 18. An image forming method, comprising exposing the photothermographic material according to any one of 1 to 17 to a laser wavelength of 400 nm to 830 nm to form an image.

{20. 18. An image forming method, comprising exposing the photothermographic material according to any one of 1 to 17 to a laser wavelength of 780 nm to 830 nm to form an image.

(4) According to the present invention, a photothermographic material and an image forming method excellent in image quality, particularly excellent in image diagnostic properties, which are equal to or higher than those of the conventional wet silver salt photosensitive material, are obtained.

The present invention will be described in more detail. Conventionally, u ^* , v ^* or a ^* , b ^* in the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space near an optical density of 1.0 is a specific numerical value. Attempts have been made to obtain a diagnostic image having a favorable visual color tone by adjusting the color tone. For example, US Pat. No. 6,174,657 describes a preferable color tone (hue angle) in a heat-developable silver salt photosensitive material. However, as a result of the study by the inventor, it has been clarified that the diagnostic images as described above are inferior in diagnostic performance to conventionally used wet silver salt photographic materials. Therefore, as a result of intensive studies, a graph in which the horizontal axis is u ^* or a ^* and the vertical axis is v ^* or b ^* in the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space. Above, u ^* , v ^* or a ^* , b ^* at various photographic densities are plotted to form a linear regression line, and by adjusting the linear regression line to the range of the present invention, the conventional wet type It has been found that it has diagnostic properties equal to or better than silver halide photosensitive materials.

The method for obtaining the photothermographic material of the present invention is not particularly limited, but a compound capable of changing the shape of developed silver or a compound capable of reducing the amount of silver necessary for obtaining a constant silver image density can be used. The properties of the photothermographic material can be adjusted by appropriately adjusting the amounts and types of these compounds used or by combining a plurality of compounds.

(4) The linear regression line having the above characteristics was achieved by adding a compound capable of changing the shape of developed silver.

(4) The components of the heat-developable silver salt photographic material of the present invention are described below. In the present invention, as the organic silver salt as a silver ion supply source for forming a silver image, a silver salt of an organic acid and a hetero organic acid, especially a long chain (10 to 30 carbon atoms, preferably 15 to 25 carbon atoms) A) Silver salts of aliphatic carboxylic acids and silver salts of nitrogen-containing heterocyclic compounds are preferred. Organic or inorganic complexes described in Research Disclosure (hereinafter, also simply referred to as RD) 17029 and 29963 in which the ligand has a value of 4.0 to 10.0 as a total stability constant for silver ions are also preferable. . Examples of these suitable silver salts include the following.

Silver salts of organic acids, for example, silver salts such as gallic acid, oxalic acid, behenic acid, stearic acid, arachidic acid, palmitic acid, lauric acid; carboxyalkylthiourea salts of silver, for example, 1- (3-carboxypropyl) thio Silver salts such as urea and 1- (3-carboxypropyl) -3,3-dimethylthiourea; silver salts or complexes of polymer reaction products of aldehydes with hydroxy-substituted aromatic carboxylic acids, for example, aldehydes (formaldehyde, acetaldehyde) , Butyraldehyde, etc.) and a hydroxy-substituted acid (eg, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid); a silver salt or complex; a thiones silver salt or complex, for example, 3- (2- Carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione, and 3-carboxymethyl- Silver salts or complexes such as -thiazoline-2-thione; from imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benzotriazole Complexes or salts of selected nitrogen acids with silver; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver mercaptides. Among them, particularly preferred silver salts include silver salts of long-chain (10 to 30, preferably 15 to 25 carbon atoms) aliphatic carboxylic acids such as silver behenate, silver arachidate and silver stearate. .

In the present invention, it is preferable that two or more kinds of organic silver salts are mixed in order to enhance developability and to form a high-density, high-contrast silver image. For example, a silver ion solution is mixed with a mixture of two or more kinds of organic acids. Is preferably prepared by mixing.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, and can be obtained by a forward mixing method, a reverse mixing method, a simultaneous mixing method, or a method described in JP-A No. 9-127643. A controlled double jet method or the like is preferably used. For example, after adding an alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.), a controlled double jet According to the method, the soap and silver nitrate are mixed to prepare a crystal of an organic silver salt. At that time, silver halide grains may be mixed.

有機 The organic silver salt according to the present invention may have various shapes, but tabular grains are preferred. In particular, it is a tabular organic silver salt particle having an aspect ratio of 3 or more, and is filled in the photosensitive layer by reducing the shape anisotropy of two substantially parallel facing surfaces (principal planes) having the largest area. In order to increase the ratio, it is preferable that the average value of the acicular ratio of the tabular organic silver salt particles measured from the main plane direction is 1.1 or more and less than 10.0. In addition, a more preferable needle ratio is 1.1 or more and less than 5.0.

The phrase "tabular organic silver salt particles having an aspect ratio of 3 or more" means that the tabular organic silver salt particles account for 50% or more of the total number of organic silver salt particles. Further, in the organic silver salt according to the present invention, the tabular organic silver salt particles having an aspect ratio of 3 or more preferably account for 60% or more of the total number of organic silver salt particles, and more preferably 70% or more (number). And it is particularly preferably at least 80% (number).

平板 The tabular grains having an aspect ratio of 3 or more are grains having a so-called aspect ratio (abbreviated as AR) of 3 or more, which is expressed by the following formula.

AR = particle size (μm) / thickness (μm)
The aspect ratio of the tabular organic silver salt grains is preferably from 3 to 20, and more preferably from 3 to 10. The reason is that if the aspect ratio is too low, the organic silver salt particles are likely to be densest, and if the aspect ratio is too high, the organic silver salt particles are likely to overlap each other and disperse in a stuck state. The above-mentioned range is preferable because light scattering and the like are likely to occur because the light-sensitive material is liable to be scattered, and as a result, the transparency of the photosensitive material is reduced.

In order to measure the particle size of the organic silver salt particles described above, the dispersed organic silver salt is diluted and dispersed on a grid with a carbon support film, and is measured using a transmission electron microscope (for example, JEOL 2000FX, (Magnification: 5000 times), and the particle size is measured. When obtaining the average particle diameter, a negative image is captured as a digital image by a scanner, and 300 or more particle diameters (equivalent circle diameters) are measured using appropriate image processing software to calculate the average particle diameter.

厚 The thickness of the organic silver salt particles described above is calculated by a method using a TEM (transmission electron microscope) as shown below.

First, the image forming layer applied on the support is attached to an appropriate holder with an adhesive, and an ultra-thin section having a thickness of 0.1 to 0.2 μm is prepared using a diamond knife in a direction perpendicular to the surface of the support. I do. The prepared ultrathin section is supported on a copper mesh, transferred onto a carbon film that has been hydrophilized by glow discharge, and cooled with liquid nitrogen to −130 ° C. or lower using a transmission electron microscope (hereinafter referred to as a TEM). A bright field image is observed at a magnification of 5,000 to 40,000, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like. At this time, as the visual field to be observed, it is preferable to appropriately select a portion where there is no break or looseness in the section.

It is preferable to use a carbon film supported by an organic film such as ultra-thin collodion or formvar, more preferably a carbon film formed on a rock salt substrate and dissolving and removing the substrate, or using the organic film in an organic solvent. A film of carbon alone obtained by ion etching. The acceleration voltage of the TEM is preferably from 80 to 400 kV, particularly preferably from 80 to 200 kV.

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

In order to determine the average thickness, the thickness of the extracted organic silver salt particles is manually measured with 300 or more suitable software, and the average value is determined.

{Circle around (2)} The average value of the acicular ratio of the tabular organic silver salt grains can be determined by the following method.

First, the photosensitive layer containing the tabular organic silver salt particles is swollen with an organic solvent capable of dissolving the photosensitive layer binder, separated from the support, and subjected to ultrasonic cleaning, centrifugation, and supernatant removal using the solvent. Repeat 5 times. The above steps are performed under safe light. Subsequently, the mixture is diluted with MEK (methyl ethyl ketone) so as to have an organic silver solid concentration of 0.01%, dispersed by ultrasonic waves, and then dropped on a polyethylene terephthalate film that has been hydrophilized by glow discharge and dried. The film on which the particles are mounted is preferably used for observation after obliquely vapor-depositing 3 nm thick Pt-C with an electron beam from a 30 ° angle with respect to the film surface by a vacuum vapor deposition apparatus.

For more information on electron microscopy techniques and sample preparation techniques, see "The Electron Microscopy Society of Japan, Kanto Chapter / Medical and Biological Electron Microscopy" (Maruzen), "The Japan Electron Microscopy Society, Kanto Chapter", Electron Microscopy Biological Specimens Production method ”(Maruzen) can be referred to.

The prepared sample is observed with a field emission scanning electron microscope (hereinafter, referred to as FE-SEM) at a accelerating voltage of 2 kV to 4 kV and a secondary electron image at a magnification of 5,000 to 20,000 times, and transferred to an appropriate recording medium. Save the image.

For the above processing, it is convenient to use a device that can AD-convert the image signal from the electron microscope main body and record it directly as digital information on the memory, but the analog image recorded on polaroid film or the like can also be used with a scanner or the like. It can be used by converting it to a digital image and performing shading correction, contrast / edge enhancement, etc. as necessary.

画像 As for an image recorded on an appropriate medium, it is preferable that one image is decomposed into at least 1024 pixels × 1024 pixels, preferably 2048 pixels × 2048 pixels or more, and image processing is performed by a computer.

As the procedure of the image processing described above, first, a histogram is prepared, and a portion corresponding to organic silver salt particles having an aspect ratio of 3 or more is extracted by binarization processing. The unavoidably agglomerated particles are cut by a suitable algorithm or manual operation to perform contour extraction. Thereafter, the maximum length (MX LNG) and the minimum width (WIDTH) of each particle are measured for at least 1000 particles, and the acicular ratio is determined for each particle by the following formula. Here, the maximum length of a particle refers to the maximum value when two points in the particle are connected by a straight line. The minimum width of a particle refers to a value when a distance between the parallel lines becomes a minimum when two parallel lines circumscribing the particle are drawn.

Needle ratio = (MX LNG) / (WIDTH)
After that, the average value of the needle ratio of all the measured particles is calculated. When the measurement is performed in the above procedure, it is preferable that the length correction per pixel (scale correction) and the correction of the two-dimensional distortion of the measurement system be sufficiently performed using a standard sample in advance. As a standard sample, Uniform Latex Particles (DULP) commercially available from Dow Chemical Co., USA is suitable, and polystyrene particles having a coefficient of variation of less than 10% with respect to a particle size of 0.1 to 0.3 μm are suitable. Preferably, specifically, a lot having a particle size of 0.212 μm and a standard deviation of 0.0029 μm is available.

The details of the image processing technology can be referred to "Hiroshi Tanaka Image Processing Applied Technology (Industry Research Committee)", and the image processing program or device is not particularly limited as long as it can perform the above operations. One example is Luzex-III manufactured by Nireco.

The method for obtaining the organic silver salt particles having the above-mentioned shape is not particularly limited, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap is preferably maintained. It is effective to optimize the ratio of silver nitrate that reacts with the soap.

平板 The tabular organic silver salt particles according to the present invention are preferably preliminarily dispersed together with a binder, a surfactant, and the like, if necessary, and then dispersed and ground using a media disperser, a high-pressure homogenizer, or the like. For the preliminary dispersion, a general stirrer such as an anchor type or a propeller type, a high-speed rotary centrifugal radiation type stirrer (dissolver), and a high-speed rotary shear type stirrer (homomixer) can be used.

Further, as the media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill as a medium stirring mill, an attritor, and other basket mills can be used. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are divided into a plurality of pieces and then collides with each other at high speed, and a type in which a thin orifice passes.

Examples of ceramics used for ceramic beads used at the time of media dispersion include Al ₂ O ₃ , BaTiO ₃ , MgO, ZrO, BeO, Cr ₂ O ₃ , SiO ₂ , SiO ₂ —Al ₂ O ₃ , and Cr ₂ O _{3 -MgO, MgO-CaO, MgO} -C, MgO-Al 2 O 3 ( _{spinel), SiC, TiO 2, K} 2 O, Na 2 O, BaO, PbO, B 2 O 3, SrTiO 3 ( strontium titanate _{), BeAl 2 O 4, Y} 3 Al 5 O 12, ZrO 2 -Y 2 O 3 ( cubic _{zirconia), 3BeO-Al 2 O 3} -6SiO 2 ( synthesis emerald), C (diamond), Si ₂ O -nH ₂ O, ticker silicon, yttrium stabilized zirconia, zirconia toughened alumina, and the like are preferable. Yttrium-stabilized zirconia and zirconia reinforced alumina (ceramics containing these zirconia are hereinafter abbreviated as zirconia) are particularly preferably used because the generation of impurities due to friction with the beads and the disperser during dispersion is small.

In the apparatus used when dispersing the tabular organic silver salt particles, it is preferable to use ceramics or diamond such as zirconia, alumina, silicon nitride, and boron nitride as a material of a member with which the organic silver salt particles are in contact, Among them, zirconia is preferably used.

(4) When performing the above dispersion, the binder concentration is preferably 0.1 to 10% of the mass of the organic silver salt, and the liquid temperature is preferably not higher than 45 ° C. from the preliminary dispersion to the main dispersion. Preferred operating conditions for the dispersion include, for example, when a high-pressure homogenizer is used as the dispersing means, 29.42 MPa to 98.06 MPa, and the number of operation times is preferably 2 or more. When a media dispersing machine is used as the dispersing means, a preferable condition is a peripheral speed of 6 m / sec to 13 m / sec.

Further, a preferred embodiment photothermographic material according to the present invention, when the support surface and the cross section perpendicular of the material observed with an electron microscope, the ratio organic silver of the organic silver salt particles exhibiting a projection area of less than 0.025 .mu.m ² An organic silver salt having a feature of exhibiting 70% or more of the total projected area of the salt particles and having a ratio of particles having a projected area of 0.2 μm ² or more of 10% or less of the total projected area of the organic silver salt particles; Further, a photosensitive emulsion containing photosensitive silver halide is coated. In such a case, it is possible to obtain a state in which the organic silver salt particles are less aggregated in the photosensitive emulsion and are uniformly distributed.

The conditions for producing a photosensitive emulsion having such characteristics are not particularly limited, and the mixing state at the time of forming the organic acid alkali metal salt soap and / or the mixing state at the time of adding silver nitrate to the soap can be favorably determined. Optimizing the ratio of silver nitrate that reacts with the soap, dispersing with a media disperser or a high-pressure homogenizer for dispersion and pulverization. In addition to the fact that the temperature from drying to the end of the main dispersion does not exceed 45 ° C., stirring at a peripheral speed of 2.0 m / sec or more using a dissolver at the time of liquid preparation is performed. Preferred conditions are mentioned.

The projection area of the organic silver salt grains having a specific projection area value as described above, the ratio of the total projection area, and the like can be determined in the same manner as described in the section for obtaining the average thickness of the tabular grains described above, using TEM ( A portion corresponding to the organic silver salt particles is extracted by a method using a transmission electron microscope).

At this time, the aggregated organic silver salt particles are treated as one particle, and the area (AREA) of each particle is determined. At least 1,000 in the same manner, preferably obtains the area about 2,000 particles, each, A: 0.025 .mu.m less than ^2, B: 0.025 .mu.m ² or more and less than 0.2 [mu] m ^2, C: 0 Classification into three groups of ² μm ² or more. In the light-sensitive material of the present invention, the total area of the particles belonging to Group A is 70% or more of the total area of the measured particles, and the total area of the particles belonging to Group C is measured. Preferably, it satisfies 10% or less.

When the measurement is performed in the above procedure, the length correction (scale correction) per pixel and the correction of the two-dimensional distortion of the measurement system are calculated in advance by using the standard sample to calculate the average value of the above-described needle ratio. It is preferable to use the method performed in the above.

The details of the image processing technology can be referred to “Hiroshi Tanaka Image Processing Application Technology (Industrial Research Council)” as described above, and the image processing program or device is not particularly limited as long as the above operation is possible. As another example, Luzex-III manufactured by Nireco is also mentioned as an example.

The organic silver salt particles according to the present invention are preferably monodisperse particles, and the preferred degree of monodispersion is 1 to 30%. By using the monodisperse particles in this range, a high-density image can be obtained. . Here, the monodispersity is defined by the following equation.

Monodispersity = {(standard deviation of particle size) / (average value of particle size)} × 100
The average particle diameter (equivalent circle diameter) of the organic silver salt described above is preferably 0.01 to 0.3 μm, and more preferably 0.02 to 0.2 μm. The average particle diameter (equivalent circle diameter) indicates the diameter of a circle having the same area as the individual particle images observed with an electron microscope.

In the present invention, in order to prevent devitrification of the light-sensitive material, the total amount of silver halide and organic silver salt is preferably 0.3 g or more and 1.5 g or less per m ² in terms of silver amount. By using this range, a preferable image can be obtained when used as a medical image. If the amount is less than 0.3 g per 1 m ² , the image density may decrease. If the amount exceeds 1.5 g per 1 m ² , fog may increase or sensitivity may decrease at the time of printing on a PS plate.

銀 The silver halide according to the present invention (hereinafter also referred to as photosensitive silver halide grains or silver halide grains) will be described. Incidentally, the silver halide according to the present invention can be inherently light-absorbing as an inherent property of silver halide crystals, or absorb visible light or infrared light by artificial physicochemical methods. To obtain a physicochemical change in the silver halide crystal and / or the crystal surface when the light is absorbed in any region within the light wavelength range from the ultraviolet light region to the infrared light region. It refers to silver halide crystal grains produced by processing.

銀 The silver halide grains used in the present invention are themselves P.I. Chiffie et Physique Photographique, published by Paul Montel, 1967, by Glafkides; F. Duffin, Photographic Emulsion Chemistry (The Focal Press, 1966); L. It can be prepared as a silver halide grain emulsion (also referred to as a silver halide emulsion) by using a method described in "Making and Coating Photographic Emulsion" (published by Zelikman et al, The Focal Press, 1964). That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and a method of reacting a soluble silver salt with a soluble halide may be any one of a one-side mixing method, a double-mixing method, a combination thereof and the like. Of these methods, the so-called controlled double jet method of preparing silver halide grains while controlling the formation conditions is preferable among the above methods. The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

Grain formation is usually divided into two stages of silver halide seed grain (nucleus) formation and grain growth, and these may be performed continuously at once, or by separating nucleus (seed grain) formation and grain growth. It may be a method of performing. The controlled double jet method for forming particles by controlling the pAg, pH and the like, which are the particle forming conditions, is preferable because the shape and size of the particles 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 generate nuclei (seed particles) (nucleation step). The silver halide grains are prepared by a grain growing step of growing grains while supplying an aqueous silver salt solution and an aqueous halide solution under controlled pAg, pH, and the like. After forming the 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, flocculation method, ultrafiltration method, and electrodialysis method. .

に お い て In the present invention, the silver halide grains are preferably monodispersed. The term “monodisperse” as used herein means that the coefficient of variation of the particle size determined by the following equation is 30% or less. It is preferably at most 20%, more preferably at most 15%.

Coefficient of variation% of particle size = (standard deviation of particle size / average value of particle size) × 100
Examples of the shape of silver halide grains include cubic, octahedral, and tetrahedral grains, tabular grains, spherical grains, rod-like grains, potato-like grains, and among these, among them, cubic, octahedral, It is preferable to use a tabular or tabular silver halide grain.

(4) The average aspect ratio when tabular silver halide grains are used is preferably 1.5 or more and 100 or less, more preferably 2 or more and 50 or less. These are described in U.S. 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 also be preferably used.

The crystal habit on the outer surface of the silver halide grains is not particularly limited. However, in the case of using a sensitizing dye having crystal habit (plane) selectivity in the adsorption reaction of the sensitizing dye on the surface of the silver halide grains. It is preferable to use silver halide grains having a relatively high proportion of crystal habit adapted to the selectivity. For example, when a sensitizing dye that selectively adsorbs to a crystal plane having a Miller index of [100] is used, the ratio of the [100] plane to the outer surface of the silver halide grain is preferably high, and this ratio is preferably 50%. % Or more, more preferably 70% or more, and particularly preferably 80% or more. The ratio of the Miller index [100] plane is determined by the T.V. method using the adsorption dependence 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 by 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 at the time of forming nuclei of the silver halide grains.

に お い て 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 is generally used for enzymatic degradation by adding a gelatin-degrading enzyme to an aqueous gelatin solution having an average molecular weight of about 100,000, hydrolyzing by adding an acid or alkali, and heating under atmospheric pressure or under pressure. By thermal decomposition, decomposition by irradiation with ultrasonic waves, or a combination of these methods.

(5) The concentration of the dispersion medium at the time of nucleation is preferably 5% by mass or less, and more preferably a low concentration of 0.05 to 3.0% by mass.

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

General formula YO (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH ₂ O) _p (CH ₂ CH ₂ O) _n Y
Wherein, Y is a hydrogen atom, a -SO ₃ M, or -CO-B-COOM, M is a hydrogen atom, an alkali metal atom, ammonium group or substituted ammonium group at carbon atom number of 5 or less in the alkyl group And B represents a linear or cyclic group forming an organic dibasic acid. m and n each represent 0 to 50, and p represents 1 to 100.

The polyethylene oxide compound represented by the above general formula is used in producing a silver halide photographic light-sensitive material, a step of producing an aqueous gelatin solution, a step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, and It has been preferably used as an antifoaming agent against remarkable foaming when the emulsion raw material is stirred or moved, such as a step of coating on a support. No.-9497. The polyethylene oxide compound represented by the above general formula also functions as an antifoaming agent at the time of nucleation.

化合物 The compound represented by the above general formula is preferably used in an amount of 1% by mass or less based on silver, more preferably 0.01 to 0.1% by mass.

The polyethylene oxide compound represented by the above general formula only needs to 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, It may be used by being added to a silver salt aqueous solution or a halide aqueous solution used at the time of formation. Preferably, it is used by adding it to a halide aqueous solution or both aqueous solutions at 0.01 to 2.0% by mass. The compound represented by the above general formula is preferably present for at least 50% of the time of the nucleation step, and more preferably for at least 70% of the time. The compound represented by the above general formula may be added as a powder or may be added after being 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-mentioned temperature range even when the temperature is gradually increased and the temperature at the end of nucleation is 40 ° C.) or vice versa.

The concentrations of the silver salt aqueous solution and the halide aqueous solution used for nucleation are 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 rate of addition of silver ion during nucleation is preferably reaction 1L per 1.5 × 10 ^-3 mol / min to 3.0 × 10 ^-1 mol / min, more preferably 3.0 × 10 ^-3 mol / Min to 8.0 × 10 ^-2 mol / min.

ＰＨ The pH at the time of nucleation can be usually set in the range of 1.7 to 10, but the pH on the alkali side is preferably pH 2 to 6, since the particle size distribution of nuclei to be formed is widened. The pBr during nucleation is usually 0.05 to 3.0, preferably 1.0 to 2.5, and more preferably 1.5 to 2.0.

The silver halide grains used in the present invention may be added to the image forming layer by any method. In this case, the silver halide grains are preferably arranged so as to be close to a reducible silver source (organic silver salt). .

The silver halide grains used in the present invention are prepared in advance and added to a solution for preparing the organic silver salt grains by separating the silver halide preparing step and the organic silver salt preparing step. Although it is preferable from the viewpoint of production control because it can be handled, as described in British Patent No. 1,447,454, a halogen component such as a halide ion is allowed to coexist with an organic silver salt forming component when preparing organic silver salt particles. By injecting silver ions into this, it is possible to produce organic silver salt particles almost simultaneously with the production thereof.

It is also possible to prepare a silver halide grain by converting an organic silver salt with a halogen-containing compound and converting the organic silver salt. That is, a silver halide-forming component is applied to a solution or dispersion of an organic silver salt prepared in advance or a sheet material containing the organic silver salt to convert a part of the organic silver salt into photosensitive silver halide. You can also.

Examples of the silver halide forming component include inorganic halogen compounds, onium halides, halogenated hydrocarbons, N-halogen compounds, and other halogen-containing compounds, and specific examples thereof are described in U.S. Pat. No. 4,009,039. No. 3,457,075, No. 4,003,749, British Patent No. 1,498,956, and JP-A-53-27027 and JP-A-53-25420, metal halides and ammonium halides Onium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide and trimethylbenzylammonium bromide, for example, iodoform, bromoform, carbon tetrachloride, 2-bromo-2-methylpropane, etc. Halogenated hydrocarbons, N-halogen compounds such as -bromosuccinimide, N-bromophthalimide, N-bromoacetamide, and others such as triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, and dichlorobenzophenone. is there. In this way, the silver halide can also be prepared by converting a part or all of the silver in the organic acid silver salt to silver halide by reacting the organic acid silver salt with the halogen ion. Further, silver halide grains produced by converting a part of these organic silver salts to separately prepared silver halide may be used in combination.

These silver halide grains, both separately prepared silver halide grains and silver halide grains obtained by conversion of organic silver salt, are preferably used in an amount of 0.001 to 0.7 mol per 1 mol of organic silver salt. It is more preferable to use 0.03 to 0.5 mol.

The silver halide used in the present invention preferably contains ions of transition metals belonging to Groups 6 to 11 of the periodic table. As the above metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable. These may be used alone or in combination of two or more of the same or different metal complexes. These metal ions may be directly introduced into silver halide as a metal salt, but can be introduced into silver halide in the form of a metal complex or complex ion. The content is preferably in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻² mol per mol of silver, more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ . 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 elements of Groups 6 to 11 of the periodic table, L represents a ligand, and m represents 0, -1, -2, -3, or -4. Specific examples of the ligand represented by L include halogen ion (fluoride ion, chloride ion, bromide ion, iodide ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Ligand, nitrosyl, thionitrosyl and the like, and preferably aquo, nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

The compound which provides the ion or complex ion of these metals is preferably added during silver halide grain formation and incorporated into silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, and physical ripening , May be added at any stage before and after chemical sensitization, nucleation, growth, preferably added at the stage of physical ripening, nucleation, more preferably added at the stage of growth, particularly preferably It is added at the stage of nucleation. In the addition, it may be added in several portions, may be added uniformly in the silver halide grains, or may be added uniformly to the silver halide grains, as disclosed in JP-A-63-29603, JP-A-2-306236, and JP-A-3-167545. As described in JP-A Nos. 4-76534, 6-110146, 5-273683, etc., they can be contained in the particles with distribution.

These metal compounds can be added after being dissolved in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a silver salt aqueous solution and a halide aqueous solution are mixed at the same time. To prepare silver halide grains by a method of simultaneous mixing of three liquids, a method of charging a required amount of an aqueous solution of a metal compound into a reaction vessel during grain formation, or a method of preparing silver halide. There is a method in which another silver halide grain doped with metal ions or complex ions in advance is sometimes added and dissolved. In particular, a method of adding an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to an aqueous halide solution. When adding to the surface of the particles, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during or at the end of physical ripening, or at the time of chemical ripening.

The separately prepared photosensitive silver halide grains can be desalted by a known desalting method such as a noodle method, flocculation method, ultrafiltration method, and electrodialysis method. It can also be used without.

(4) The silver halide grains used in the present invention can be subjected to chemical sensitization. For example, according to the methods disclosed in JP-A-2001-249428 and JP-A-2001-249426, a chemical sensitization center (chemical reaction) is performed using a compound having a chalcogen atom such as sulfur or a noble metal compound which releases a noble metal ion such as a gold ion. (Sensitizing nucleus). In the present invention, it is particularly preferable to use both the chemical sensitization using the compound having a chalcogen atom and the chemical sensitization using a noble metal compound.

に お い て In the present invention, it is preferable that the compound is chemically sensitized by a compound containing a chalcogen atom shown below.

The compound containing a chalcogen atom useful as an organic sensitizer is preferably a compound having a group capable of adsorbing to silver halide and an unstable chalcogen atom site.

As these organic sensitizers, organic sensitizers having various structures disclosed in JP-A-60-150046, JP-A-4-109240, and JP-A-11-218874 can be used. Of these, it is preferable that at least one compound having a structure in which a chalcogen atom is connected to a carbon atom or a phosphorus atom by a double bond is used.

The amount of the compound containing a chalcogen atom as an organic sensitizer is variable, chalcogen compound to be used, silver halide grains will vary due reaction environment when subjected to chemical sensitization, per mol of silver halide, 10 ^{- The amount} is preferably from ⁸ to 10 ^-2 mol, more preferably from 10 ^-7 to 10 ^-3 mol. The chemical sensitizing environment in the present invention is not particularly limited, but in the presence of a compound capable of eliminating silver chalcogen or silver nuclei on the photosensitive silver halide grains or reducing the size thereof, and in particular, silver nuclei. Chalcogen sensitization is preferably performed using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing the compound. The sensitization condition is that the pAg is preferably 6 to 11, more preferably 7 to 11. -10, and the pH is preferably 4-10, more preferably 5-8, and the sensitization is preferably performed at a temperature of 30 ° C. or less.

Therefore, in the photothermographic material of the present invention, the photosensitive silver halide is heated to a temperature of 30 ° C using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei on the grains. It is preferable to use a photosensitive silver halide emulsion which has been subjected to chemical sensitization at a temperature of not more than ℃, mixed with an organic silver salt, dispersed, dehydrated and dried.

化学 Further, the chemical sensitization using these organic sensitizers is preferably performed in the presence of a spectral sensitizing dye or a heteroatom-containing compound having adsorptivity to silver halide grains. By performing chemical sensitization in the presence of a compound having adsorptivity to silver halide, dispersion of the chemical sensitization center nucleus can be prevented, and high sensitivity and low fog can be achieved. The spectral sensitizing dye used in the present invention will be described later. The heteroatom-containing compound having adsorptivity to silver halide is preferably a nitrogen-containing heterocyclic compound described in JP-A-3-24537. No. In the nitrogen-containing heterocyclic compound used in the present invention, the heterocyclic ring is a pyrazole ring, a pyrimidine ring, a 1,2,4-triazole ring, a 1,2,3-triazole ring, a 1,3,4-thiadiazole ring, , 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, And, for example, a triazolotriazole ring, diazaindene ring, triazaindene ring, and pentaazaindene ring. A condensed heterocyclic ring of a monocyclic heterocycle and an aromatic ring, for example, a phthalazine ring, a benzimidazole ring, an indazole ring, a benzthiazole ring, and the like can also be applied.

Of these, azaindene rings are preferred, and azaindene compounds having a hydroxyl group as a substituent, such as hydroxytriazaindene, hydroxytetraazaindene, and hydroxypentaazaindene compounds, are more preferred.

The heterocyclic ring may have a substituent other than a 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.

The addition amount of these heterocyclic compounds varies over a wide range depending on the size, composition, and other conditions of silver halide grains, but the approximate amount is 10 ^-6 mole per mole of silver halide. ^-1 mol, preferably 10 ^-4 mol ^{-10 -1} mol.

銀 As described above, the silver halide grains according to the present invention can be sensitized with a noble metal using a compound that releases a noble metal ion such as a gold ion. For example, chloroaurate or an organic gold compound can be used as a gold sensitizer.

In addition to the above-described sensitization methods, reduction sensitization methods and the like can also be used. Examples of the reduction-sensitized shell-like compounds include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, and borane compounds. , A silane compound, a polyamine compound, and the like. Further, reduction sensitization can be achieved by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less.

The silver halide subjected to chemical sensitization according to the present invention may be one formed in the presence of an organic silver salt, one formed under the absence of an organic silver salt, or a mixture of both. May be used.

(4) It is preferable that the photosensitive silver halide grains used in the present invention are subjected to spectral sensitization by adsorbing a spectral sensitizing dye. As the spectral sensitizing dye, cyanine dye, merocyanine dye, complex cyanine dye, complex merocyanine dye, holopolar cyanine dye, styryl dye, hemicyanine dye, oxonol dye, hemioxonol dye, and the like can be used. For example, JP-A-63-159814, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, JP-A-63-15245, U.S. Pat. The sensitizing dyes described in 4,740,455, 4,741,966, 4,751,175, and 4,835,096 can be used. Useful sensitizing dyes for use in the present invention are described, for example, in the literature described or cited in RD17643 IV-A (p.23, December 1978, p.23) and 18431X (p.437, August 1978). I have. In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various laser imagers and scanner light sources. For example, compounds described in JP-A-9-34078, JP-A-9-54409, and JP-A-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. Preferred useful merocyanine dyes include, in addition to the above basic nuclei, acidic nuclei such as a thiohydantoin nucleus, a rhodanine nucleus, an oxazolidinedione nucleus, a thiazolinedione nucleus, a barbituric acid nucleus, a thiazolinone nucleus, a malononitrile nucleus and a pyrazolone nucleus. including.

に お い て In the present invention, it is particularly preferable to use a sensitizing dye having a spectral sensitivity in the infrared. The infrared spectral sensitizing dyes preferably used in the present invention include, for example, those disclosed in U.S. Pat. Nos. 4,536,473, 4,515,888, and 4,959,294. And external spectral sensitizing dyes.

赤 外 The infrared spectral sensitizing dye used in the present invention is particularly preferably a long-chain polymethine dye characterized by having a sulfinyl group substituted on the benzene ring of a benzazole ring.

The above-mentioned infrared sensitizing dyes are described in, for example, FM Hammer, The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanine Dyes and Related Documents (A. Weissberger, Germany, 1964). It can be easily synthesized by the method.

These infrared sensitizing dyes may be added at any time after the preparation of the silver halide. For example, they may be added to a solvent or in the form of fine particles dispersed in a so-called solid dispersion state of silver halide grains or silver halide. Grains / organic silver salt grains. Also, like the heteroatom-containing compound having an adsorptivity to the silver halide grains, the chemical sensitization can be performed after adding and adsorbing the silver halide grains prior to the chemical sensitization. Thereby, the dispersion of the chemical sensitization center nucleus can be prevented, and high sensitivity and low fog can be achieved.

In the present invention, the above-mentioned spectral sensitizing dyes may be used alone, or a combination thereof may be used, and a combination of sensitizing dyes is often used particularly for supersensitization.

The emulsion containing silver halide grains or organic silver salt grains used in the photothermographic material of the present invention, together with the sensitizing dye, does not substantially absorb a dye having no spectral sensitizing effect or visible light by itself. The emulsion may contain a substance exhibiting a supersensitizing effect, whereby the silver halide grains may be supersensitized.

Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in RD17643 (December, 1978), page 23, IV, J, or JP-B 9-25500, 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. In the present invention, a supersensitizer represented by the following general formula is used. A heteroaromatic mercapto compound or a mercapto derivative compound is preferred.

General formula Ar-SM
In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic heterocycle or an aromatic fused ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. Preferred aromatic heterocycles or aromatic condensed rings are benzimidazole, naphthoimidazole, benzthiazole, naphthothiazole, benzoxazole, naphthoxazole, benzselenazole, benztellurazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, Examples include pyridazine, pyrazine, pyridine, purine, quinoline, and quinazoline. However, other aromatic heterocycles are also included.

In the present invention, it is preferable that a mercapto derivative compound which substantially forms the above-mentioned mercapto compound when contained in a dispersion of an organic acid silver salt or a silver halide grain emulsion is contained. Particularly, a mercapto derivative compound represented by the following general formula is mentioned as a preferable example.

General formula Ar-SS-Ar
Ar in the formula has the same meaning as in the case of the mercapto compound represented by the above general formula.

The aromatic heterocyclic ring or aromatic condensed ring is, for example, a halogen atom (eg, Cl, Br, I), a hydroxyl group, an amino group, a carboxyl group, an alkyl group (eg, one or more carbon atoms, preferably , Having 1 to 4 carbon atoms) and an alkoxy group (for example, having 1 or more carbon atoms, preferably having 1 to 4 carbon atoms) sell.

In the present invention, in addition to the above-described supersensitizer, a compound represented by the following general formula (1) and a macrocyclic compound disclosed in JP-A-2001-330918 are used as a supersensitizer. it can.

In the formula, H ₃₁ Ar represents an aromatic hydrocarbon group or an aromatic heterocyclic group, T ₃₁ represents a divalent linking group consisting of an aliphatic hydrocarbon group or a mere bond, and J ₃₁ represents an oxygen atom, sulfur Represents a divalent linking group containing one or more atoms or nitrogen atoms or a simple bond. Ra, Rb, Rc and Rd each represent a hydrogen atom, an acyl group, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group, and bond between Ra and Rb, Rc and Rd, Ra and Rc or Rb and Rd To form a nitrogen-containing heterocyclic group. M ₃₁ represents an ion necessary to compensate for intramolecular charge, k ₃₁ represents the number of ions necessary to compensate for an intramolecular charge.

In the general formula (1), as the divalent linking group consisting of the aliphatic hydrocarbon group represented by T ₃₁ , a linear, branched or cyclic alkylene group (preferably having 1 to 20 carbon atoms, more preferably 1 to 20 carbon atoms) To 16, more preferably 1 to 12 alkylene groups), alkenylene groups (preferably having 2 to 20, more preferably 2 to 16, more preferably 2 to 12 alkenylene groups), and alkynylene groups (preferably having 2 to 12 carbon atoms). 2-20, more preferably 2-16, and still more preferably 2-12 alkynylene groups).

各 Each of the above groups may have a substituent.

Oxygen atom represented by J _31, as the divalent linking group containing one or more sulfur atom or a nitrogen atom, for example, include the following. Also, a combination of these may be used.

Here, Re and Rf have the same meanings as those defined in Ra to Rd, respectively.

H ₃₁ Ar represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and the aromatic hydrocarbon group represented by H ₃₁ Ar preferably has 6 to 30 carbon atoms, and more preferably has 3 to 30 carbon atoms. 6 to 20 monocyclic or condensed aryl groups, such as a phenyl group and a naphthyl group, and particularly preferably a phenyl group. The aromatic heterocyclic group represented by H ₃₁ Ar is a 5- to 10-membered unsaturated heterocyclic group containing at least one atom of N, O and S, and the heterocyclic ring in these groups is It may be a single ring or may form a condensed ring with another ring. The heterocycle in such a heterocyclic group is preferably a 5- to 6-membered aromatic heterocycle, and a benzo-fused ring thereof, more preferably a 5- to 6-membered aromatic heterocycle containing a nitrogen atom, and It is a benzo-fused ring, more preferably a 5- to 6-membered aromatic heterocycle containing 1 to 2 nitrogen atoms, and the benzo-fused ring.

The aromatic hydrocarbon group and the aromatic heterocyclic group represented by H ₃₁ Ar may have a substituent, and examples of the substituent include those similar to the groups exemplified as the substituent of T _31. The preferred range is also the same. These substituents may be further substituted, and when there are two or more substituents, each may be the same or different. The group represented by H ₃₁ Ar is preferably an aromatic heterocyclic group.

Ra, Rb, Rc, aliphatic hydrocarbon groups represented by Rd, aryl group and heterocyclic group, an aliphatic hydrocarbon group At a the T _31, similar to that taken as examples of the aryl group and heterocyclic group And preferred ranges are also the same. The acyl group represented by Ra, Rb, Rc, and Rd is an aliphatic or aromatic group having 1 to 12 carbon atoms, and specific examples include acetyl, benzoyl, formyl, and pivaloyl. Examples of the nitrogen-containing heterocyclic group formed by bonding between Ra and Rb, Rc and Rd, Ra and Rc or Rb and Rd include a 3- to 10-membered saturated or unsaturated heterocyclic group (for example, piperidine ring, piperazine Ring, acridine ring, pyrrolidine ring, pyrrole ring, morpholine ring and the like).

Specific examples of the acid anion as ion necessary to compensate for intramolecular charge, represented by M ₃₁ for example, a halogen ion (e.g. chloride ion, bromide ion, iodide ion, etc.), p-toluenesulfonate ion, peroxide Chlorate ion, boron tetrafluoride ion, sulfate ion, methyl sulfate ion, ethyl sulfate ion, methanesulfonate ion, trifluoromethanesulfonate ion and the like can be mentioned.

大 A macrocyclic compound containing a hetero atom is a 9 or more-membered macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a hetero atom. Representative compounds are crown ethers, which were synthesized by Pedersen below in 1967, and have been synthesized many times since their unique properties were reported. These compounds are C.I. J. Pedersen, Journal of American Chemical Society vol. 86 (2495), 7017-7036 (1967); W. Gokel, S.M. H. Korzeniowski, "Macrocyclic @ polyethr @ synthesis", Springer-Verlag. (1982); Oda, Shono, and Tabushi, eds., "Chemistry of Crown Ethers" Kagaku Doujinshi (1978); Tabushi, et al., "Host-Guest", Kyoritsu Shuppan (1979); 1987). Specific examples of the macrocyclic compound containing a hetero atom include those described in paragraphs 0030 to 0037 of JP-A-2000-347343.

(4) The supersensitizer is preferably used in the emulsion layer containing the organic silver salt and silver halide grains in the range of 0.001 to 1.0 mol per mol of silver. It is particularly preferable to use it in the range of 0.01 to 0.5 mol per mol of silver.

Examples of the compound capable of changing the shape of the developed silver include a reducing agent. In the present invention, as the reducing agent (silver ion reducing agent), it is particularly preferable to use a compound in which at least one of the reducing agents is a bisphenol derivative alone or in combination with another reducing agent having a different chemical structure. In the photothermographic material according to the present invention, by appropriately using such a reducing agent, the shape of developed silver is changed, and the CIE 1976 (L ^* u ^* v ^* ) color space or (L ^* a ^* b ^* ) is used. A linear regression line for u ^* v ^* or a ^* b ^* in the color space can be adjusted.

還 元 As the reducing agent used in the present invention, the reducing agent represented by the formula (A-1), more preferably the formula (A-2) is used.

In the general formula (A-1), Z represents an atomic group necessary for forming a 3- to 10-membered ring together with a carbon atom, and the 3- to 10-membered ring is preferably a non-aromatic ring. Specifically, as a 3-membered ring, cyclopropyl, aziridyl, oxiranyl, as a 4-membered ring, cyclobutyl, cyclobutenyl, oxetanyl, azetidinyl, as a 5-membered ring, cyclopentyl, cyclopentenyl, cyclopentadienyl, tetrahydrofuranyl, pyrrolidinyl, tetrahydrogen Thienyl, as a 6-membered ring, cyclohexyl, cyclohexenyl, cyclohexadienyl, tetrahydropyranyl, pyranyl, piperidinyl, dioxanyl, tetrahydrothiopyranyl, norcaranyl, norpinanyl, norbornyl, as a 7-membered ring, cycloheptyl, cycloheptinyl, cycloheptayl Enyl, 8-membered ring is cyclooctanyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, 9-membered ring is cyclononanyl, cyclononenyl, cyclononadienyl, cyclononatrienyl, 10-membered ring is cyclodecanyl, cyclodecenyl , Cyclodecadienyl, cyclodecatrienyl and the like.

Preferably it is a 3- to 6-membered ring, more preferably a 5- to 6-membered ring, most preferably a 6-membered ring, and among them, a hydrocarbon ring containing no hetero atom is preferable. The ring may form a spiro bond with another ring through a spiro atom, or may be condensed in any way with another ring including an aromatic ring. The ring may have any substituent. The hydrocarbon ring is particularly preferably a hydrocarbon ring having an alkenyl structure or an alkynyl structure containing -C = C- or -C や C-.

Specific examples of the substituent include a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, etc.), an alkyl group (e.g., a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, etc., cycloalkyl group (eg, cyclohexyl group, cycloheptyl group, etc.), alkenyl group (eg, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl) -3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, etc.), cycloalkenyl group (eg, 1-cycloalkenyl group, 2-cycloalkenyl group, etc.), alkynyl group (eg, ethynyl group, 1-propynyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propoxy group, etc.), alkylcarbonyloxy (Eg, acetyloxy group), alkylthio group (eg, methylthio group, trifluoromethylthio group, etc.), carboxyl group, alkylcarbonylamino group (eg, acetylamino group, etc.), ureido group (eg, methylaminocarbonylamino group) An alkylsulfonylamino group (e.g., methanesulfonylamino group), an alkylsulfonyl group (e.g., methanesulfonyl group, trifluoromethanesulfonyl group, etc.), a carbamoyl group (e.g., carbamoyl group, N, N-dimethylcarbamoyl group, N-morpholinocarbonyl group, etc.), sulfamoyl group (sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkyl sulfone Amide group (eg, methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group (eg, amino group, N, N-dimethylamino group, N, N-diethylamino group, etc.), sulfo group, phosphono group, sulfite Group, sulfino group, alkylsulfonylaminocarbonyl group (eg, methanesulfonylaminocarbonyl group, ethanesulfonylaminocarbonyl group, etc.), alkylcarbonylaminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.), alkynylaminocarbonyl group (Eg, acetamidocarbonyl group, methoxyacetamidocarbonyl group, etc.), alkylsulfinylaminocarbonyl group (eg, methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group) And the like). When there are two or more substituents, they may be the same or different. Particularly preferred substituents are alkyl groups.

R ₁ and R ₂ each represent a group that can be substituted on the benzene ring, and examples thereof include a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and a heterocyclic group. Among these groups, a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group is more preferable. Specifically, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, iso-pentyl, 2-ethyl-hexyl, octyl, decyl, cyclohexyl, and cycloheptyl. Alkenyl groups such as ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-methylcyclohexyl group and the like; Examples of the alkynyl group such as -cycloalkenyl group and 2-cycloalkenyl group include an ethynyl group and a 1-propynyl group. More preferred are a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a cyclohexyl group, a 1-methylcyclohexyl group, and the like. Preferred are a methyl group, t-butyl group and 1-methylcyclohexyl group, and most preferred is a methyl group. Specific examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. Specific examples of the heterocyclic group include a pyridine group, a quinoline group, an isoquinoline group, an imidazole group, a pyrazole group, a triazole group, an oxazole group, a thiazole group, an oxadiazole group, a thiadiazole group, and an aromatic heterocyclic group such as a tetrazole group. Non-aromatic heterocyclic groups such as piperidino group, morpholino group, tetrahydrofuryl group, tetrahydrothienyl group and tetrahydropyranyl group are exemplified. These groups may further have a substituent, and examples of the substituent include the aforementioned substituents on the ring. A plurality of R ₁ and R ₂ may be the same or different, but most preferably all are methyl groups.

R _X represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Specifically, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, iso-pentyl, 2-ethyl-hexyl, octyl, decyl, cyclohexyl, and cycloheptyl. Group, 1-methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-cycloalkenyl group, 2 -Cycloalkenyl group, ethynyl group, 1-propynyl group and the like. More preferred are a methyl group, an ethyl group, an isopropyl group and the like. Preferably, R _X is a hydrogen atom.

Q ₀ represents a group that can be substituted on the benzene ring, and specifically, an alkyl group having 1 to 25 carbon atoms (a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a hexyl group) , Cyclohexyl group, etc.), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkynyl group (propargyl group, etc.), glycidyl group, acrylate group, methacrylate Group, aryl group (phenyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, slipholanyl group, piperidinyl group, Pyrazolyl group, tetrazolyl group, etc.), halogen atom ( A hydrogen atom, a bromine atom, an iodine atom, a fluorine atom, etc., an alkoxy group (a methoxy group, an ethoxy group, a propyloxy group, a pentyloxy group, a cyclopentyloxy group, a hexyloxy group, a cyclohexyloxy group, etc.), an aryloxy group (phenoxy group) Group), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group) , Butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, Laminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc., urethane group (methylureide group, ethylureide group, pentylureide group, cyclohexylureide group, phenylureide 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, dimethyl group) Aminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group Acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), Amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group, etc. Can be mentioned. These groups may be further substituted with these groups. n and m each represent an integer of 0 to 2, and most preferably n and m are both 0.

L represents a divalent linking group, preferably an alkylene group such as methylene, ethylene and propylene, and preferably has 1 to 20 carbon atoms, and more preferably 1 to 5 carbon atoms. k represents an integer of 0 to 1, but most preferably k = 0.

In formula (A-2), Q ₁ represents a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and Q ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl. Represents a group, an aryl group, or a heterocyclic group, and specific examples of the halogen atom include chlorine, bromine, fluorine, and iodine. Preferred are fluorine, chlorine and bromine. Specifically, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, iso-pentyl, 2-ethyl-hexyl, octyl, decyl, cyclohexyl, and cycloheptyl. Group, 1-methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-cycloalkenyl group, 2 -Cycloalkenyl group, ethynyl group, 1-propynyl group and the like. More preferably, they are a methyl group and an ethyl group. Specific examples of the aryl group include a phenol group and a naphthyl group. Preferred examples of the heterocyclic group include a 5- to 6-membered heteroaromatic group such as a pyridyl group, a furyl group, a thienyl group, and an oxazolyl group. G represents a nitrogen atom or a carbon atom, preferably a carbon atom. ng represents 0 or 1, but is preferably 1.

Most preferably, Q ₁ is a methyl group. Q ₂ is preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

Z ₂ represents an atomic group necessary to configure the non-aromatic ring of 3 to 10 members together with the carbon atoms and G, as the non-aromatic ring of the 3- to 10-membered, the aforementioned general formula (A- It is the same as that in 1).

R ₁ , R ₂ , R _X , Q ₀ , k, n, and m have the same meanings as those in formula (A-1).

In the present invention, it is preferable to use a compound represented by the general formula (A-1) and a compound represented by the following general formula (A-3) in combination. The combined ratio is preferably [mass of general formula (A-1)]: [mass of general formula (A-3)] = 95: 5 to 55:45, more preferably 90:10 to 60:40. .

In the general formula (A-3), X ₁ represents a chalcogen atom or CHR. The chalcogen atom is sulfur, selenium or tellurium, preferably a sulfur atom. R in CHR represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, or an alkynyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom, and a substituted or unsubstituted alkyl group. An alkyl group having 1 to 20 carbon atoms is preferred. Specific examples of the alkyl group include, for example, methyl, ethyl, propyl, butyl, hexyl, heptyl, vinyl, allyl, butenyl, hexadienyl, ethenyl-2-propenyl, and 3-butenyl. Group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group and the like.

These groups may further have a substituent. Examples of the substituent include a halogen atom (eg, a fluorine atom, a chlorine atom, a bromine atom, etc.), a cycloalkyl group (eg, a cyclohexyl group, a cycloheptyl group, etc.) A cycloalkenyl group (eg, 1-cycloalkenyl group, 2-cycloalkenyl group, etc.), an alkoxy group (eg, methoxy group, ethoxy group, propoxy group, etc.), an alkylcarbonyloxy group (eg, acetyloxy group, etc.), Alkylthio group (eg, methylthio group, trifluoromethylthio group, etc.), carboxyl group, alkylcarbonylamino group (eg, acetylamino group, etc.), ureido group (eg, methylaminocarbonylamino group, etc.), alkylsulfonylamino group (eg, , Methanesulfonylamino group, etc.) Group (eg, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), carbamoyl group (eg, carbamoyl group, N, N-dimethylcarbamoyl group, N-morpholinocarbonyl group, etc.), sulfamoyl group (sulfamoyl group, N, N-dimethyl group) Sulfamoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkylsulfonamide group (eg, methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group ( For example, amino group, N, N-dimethylamino group, N, N-diethylamino group, etc., sulfo group, phosphono group, sulfite group, sulfino group, alkylsulfonylaminocarbonyl group (for example, methanesulfonylaminocarbonyl group, ethanesulfonyl group) A Alkylcarbonylaminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.), alkynylaminocarbonyl group (eg, acetamidocarbonyl group, methoxyacetamidocarbonyl group, etc.), alkylsulfinylaminocarbonyl group (eg, Methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group, etc.). When there are two or more substituents, they may be the same or different.

R ₃ represents an alkyl group, which may be the same or different, 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a t-amyl group , T-octyl group, cyclohexyl group, cyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopropyl group and the like.

The substituent of the alkyl group is not particularly limited, and examples thereof include an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group, and an acyl group. Carbamoyl group, ester group, halogen atom and the like. Further, (Q ₀ ) _n and (Q ₀ ) _m may form a saturated ring. R ₁ is preferably a secondary or tertiary alkyl group, and preferably has 2 to 20 carbon atoms. More preferably, it is a tertiary alkyl group. More preferred are a t-butyl group, a t-amyl group and a 1-methylcyclohexyl group, and most preferred is a 1-methylcyclohexyl group.

R ₄ represents a hydrogen atom or a group that can be substituted on a benzene ring. Examples of the group that can be substituted on the benzene ring include a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom, an alkyl group, an aryl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, an amino group, an acyl group, Examples include an acyloxy group, an acylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, an alkylthio group, a sulfonyl group, an alkylsulfonyl group, a sulfinyl group, a cyano group, and a heterocyclic group. A plurality of R ₃ and R ₄ may be the same or different.

R ₄ preferably has 1 to 5 carbon atoms, more preferably 1 to 2 carbon atoms. These groups may further have a substituent, and as the substituent, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, etc.), an alkyl group (for example, a methyl group, an ethyl group, a propyl group, Butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, etc., cycloalkyl group (eg, cyclohexyl group, cycloheptyl group, etc.), alkenyl group (eg, ethenyl-2-yl) Propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, etc., cycloalkenyl group (for example, 1-cycloalkenyl group, 2-cycloalkenyl group) Alkynyl group (eg, ethynyl group, 1-propynyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propoxy group) ), An alkylcarbonyloxy group (eg, acetyloxy group, etc.), an alkylthio group (eg, methylthio group, trifluoromethylthio group, etc.), a carboxyl group, an alkylcarbonylamino group (eg, acetylamino group, etc.), a ureido group (eg, , Methylaminocarbonylamino group, etc.), alkylsulfonylamino group (eg, methanesulfonylamino group), alkylsulfonyl group (eg, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), carbamoyl group (eg, carbamoyl group, N, N-dimethylcarbamoyl group, N-morpholinocarbonyl group, etc.), sulfamoyl group (sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro , Cyano group, alkylsulfonamide group (eg, methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group (eg, amino group, N, N-dimethylamino group, N, N-diethylamino group, etc.), sulfo group , A phosphono group, a sulfite group, a sulfino group, an alkylsulfonylaminocarbonyl group (eg, methanesulfonylaminocarbonyl group, ethanesulfonylaminocarbonyl group, etc.), an alkylcarbonylaminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.) ), An alkynylaminocarbonyl group (eg, acetamidocarbonyl group, methoxyacetamidocarbonyl group, etc.), an alkylsulfinylaminocarbonyl group (eg, methanesulfinylaminocarbonyl group, ethanol And the like. R ₄ is preferably an alkyl group having 1 to 20 carbon atoms, and most preferably a methyl group.

Q ₀ has the same meaning as that in formula (A-1). Further, Q ₀ may form a saturated ring with R ₃ and R ₄ . Q ₀ is preferably a hydrogen atom, a halogen atom, or an alkyl group, and more preferably a hydrogen atom.

具体 Specific examples of the compounds represented by formulas (A-1), (A-2) and (A-3) of the present invention are listed below, but the present invention is not limited thereto.

化合物 The compounds of the present invention represented by formulas (A-1), (A-2) and (A-3) can be easily synthesized by a conventionally known method. A preferred synthesis scheme is shown below, taking as an example a case corresponding to the general formula (A-1).

That is, preferably, 2 equivalents of phenol and 1 equivalent of aldehyde are dissolved or suspended without a solvent or with an appropriate organic solvent, and a catalytic amount of an acid is added. By reacting for 0.5 to 60 hours, the desired compound corresponding to the general formula (A-1) can be obtained in good yield. The same applies to the compound represented by formula (A-2) or (A-3).

The organic solvent is preferably a hydrocarbon organic solvent, and specific examples include benzene, toluene, xylene, dichloromethane, chloroform and the like. Preferably, it is toluene. It is most preferable to carry out the reaction without solvent from the viewpoint of yield. As the acid catalyst, any inorganic acid or organic acid can be used, but concentrated hydrochloric acid, p-toluenesulfonic acid, and phosphoric acid are preferably used. The amount of the catalyst is preferably 0.001 to 1.5 equivalents to the corresponding aldehyde. The reaction temperature is preferably around room temperature (15 to 25 ° C.), and the reaction time is preferably 3 to 20 hours.

In the present invention, U.S. Pat. Nos. 3,589,903 and 4,021,249 or British Patent 1,486,148 and JP-A-51-51933, JP-A-50-36110, and JP-A-50-116023 are disclosed. And polyphenol compounds described in JP-B-52-84727 or JP-B-51-35727, such as 2,2'-dihydroxy-1,1'-binaphthyl and 6,6'-dibromo-2,2'-dihydroxy-1. Bisnaphthols described in U.S. Pat. No. 3,672,904, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzene Described in U.S. Patent No. 3,801,321 such as sulfonamidophenol and 4-benzenesulfonamidonaphthol Sulfonamidophenols or sulfonamidonaphthols, such as can be used as the silver ion reducing agent.

In addition, U.S. Pat. Nos. 3,589,903 and 4,021,249 or British Patent 1,486,148 and JP-A-51-51933, JP-A-50-36110, JP-A-50-116023, Polyphenol compounds described in JP-A-52-84727 or JP-B-51-35727, such as 2,2'-dihydroxy-1,1'-binaphthyl, 6,6'-dibromo-2,2'-dihydroxy-1, Bisnaphthols described in U.S. Pat. No. 3,672,904, such as 1'-binaphthyl, and furthermore, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfone Amidophenol, 4-benzenesulfonamidonaphthol and the like are described in U.S. Pat. No. 3,801,321. Sulfonamidophenols or sulfonamidonaphthols, such as may also be mentioned.

The amount of the reducing agent including the compounds represented by the general formulas (A-1), (A-2) and (A-3) is preferably 1 × 10 ⁻² to 10 mol per mol of silver. And particularly preferably 1 × 10 ^{-2 to} 1.5 mol.

The amount of the reducing agent used in the photothermographic material of the present invention varies depending on the type of the organic silver salt and the reducing agent and other additives, but is generally 0.05 to 10 per mol of the organic silver salt. Molar, preferably 0.1 to 3 moles is suitable. Further, within this range, two or more of the above-mentioned reducing agents may be used in combination. In the present invention, it is preferable that the reducing agent be added to and mixed with a photosensitive emulsion solution composed of photosensitive silver halide and organic silver salt particles and a solvent immediately before coating, and the photographic performance fluctuation due to the stagnation time is small, which is preferable. is there.

The compound represented by formula (A-4) will be described in detail. In Formula (A-4), R ₄₁ represents a substituted or unsubstituted alkyl group. In Formula (A-4), when R ₄₂ is a substituent other than a hydrogen atom, R ₄₁ represents an alkyl group. As the alkyl group, an alkyl group having 1 to 30 carbon atoms is preferable, and the alkyl group may be unsubstituted or may have a substituent. As the alkyl group, specifically, methyl, ethyl, butyl, octyl, isopropyl, tert-butyl, tert-octyl, tert-amyl, sec-butyl, cyclohexyl, 1-methyl-cyclohexyl group and the like are preferable, and the isopropyl group is more preferable. It is preferably a sterically large group (eg, isopropyl group, isononyl group, tert-butyl group, tert-amyl group, tert-octyl group, cyclohexyl group, 1-methyl-cyclohexyl group, adamantyl group, etc.) Of these, a secondary or tertiary alkyl group is preferable, and tertiary alkyl groups such as tert-butyl, tert-octyl, and tert-amyl group are particularly preferable. When R ₄₁ has a substituent, examples of the substituent 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 sulfonamide group, an acyloxy group, an oxycarbonyl group, and a carbamoyl group. , A sulfamoyl group, a sulfonyl group, a phosphoryl group and the like.

R ₄₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted acylamino group. Alkyl group R ₄₂ represents preferably an alkyl group having 1 to 30 carbon atoms, an acylamino group represented by R ₄₂ is preferably an acylamino group having 1 to 30 carbon atoms. Description of the alkyl group is the same as R _41. The acylamino group may be unsubstituted or have a substituent, and specific examples include an acetylamino group, an alkoxyacetylamino group, and an aryloxyacetylamino group. _R42 is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include a methyl group, an isopropyl group, and a t-butyl group. R ₄₁ and R ₄₂ are never a 2-hydroxyphenylmethyl group.

R ₄₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group. The alkyl group represented by R ₄₃ is preferably an alkyl group having 1 to 30 carbon atoms, and the description of the alkyl group is the same as that of R ₄₁ . R ₄₃ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, specifically, a methyl group, an isopropyl group, and a tert-butyl group. Further, it is preferable that one of R ₄₂ and R ₄₃ is a hydrogen atom.

R ₄₄ represents a group substitutable on the benzene ring, the same groups as described for example in R ₂ of the general formula (A-1). Preferred are substituted or unsubstituted alkyl group having 1 to 30 carbon atoms as R _44, an oxycarbonyl group having 2 to 30 carbon atoms, 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. preferable. The substituents of these alkyl groups may be further substituted with these substituents.

Alternatively, R ₄₄ represents a substituent such that the compound of the general formula (A-4) becomes a compound of the general formula (A-5) described below. That is, a more preferred structure among the compounds of the general formula (A-4) is represented by the following general formula (A-5).

R ₅₁ , R ₅₂ , R ₅₃ and R ₅₄ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. The substituent on the alkyl group is not particularly limited, but is preferably an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a sulfonamide group, a sulfonyl group, a phosphoryl group. , An acyl group, a carbamoyl group, an ester group, a halogen atom and the like. In R ₅₁ , R ₅₂ , R ₅₃ and R ₅₄ , groups sterically larger than the isopropyl group (for example, isopropyl group, isononyl group, tert-butyl group, tert-amyl group, tert-octyl group, cyclohexyl group, It is preferable that at least one 1-methyl-cyclohexyl group, an adamantyl group and the like be present, and more preferably two or more. As a group sterically larger than the isopropyl group, a tertiary alkyl group such as tert-butyl, tert-octyl, and tert-amyl group are particularly preferable. L ₅ in the general formula (A-5) is the same as that described for L in the general formula (A-1).

Examples of the compounds represented by formulas (A-4) to (A-5) include compounds (II-1) to (II-40) described in JP-A-2002-169249, “0032” to “0038”, and EP1211093. Compounds (ITS-1) to (ITS-12) described in “0026” of the above.

Specific examples of the compound represented by formula (A-4) or (A-5) that can be used in the present invention are shown below, but it should not be construed that the invention is limited thereto.

As a method for adding the compound represented by the general formula (A-4) or (A-5), a method similar to the method for adding the compound represented by the general formula (A-1) may be used. It may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, and a solid fine particle dispersion form, and may be contained in the photosensitive material.

Compounds represented by the general formulas (A-1) to (A-3) of the compound of the general formula (A-4) (hindered phenol compound) (including the compound of the general formula (A-5)) (o The addition ratio (molar ratio) to the total amount of the polyphenols of the coordinated linkage is {compounds of general formulas (A-4) to (A-5)} / {compounds of general formulas (A-1) to (A-3). Compound｝ (molar ratio) is in the range of 0.001 to 0.2, preferably in the range of 0.005 to 0.1, and more preferably in the range of 0.008 to 0.05.

The compounds of the general formulas (A-1) to (A-5) are preferably contained in an image forming layer containing an organic silver salt. They may be contained, or both may be contained in the non-image forming layer. When the image forming layer is composed of a plurality of layers, they may be contained in separate layers. In the photothermographic material of the present invention, a phenol derivative represented by the formula (A) described in JP-A-2000-267222 is preferably used as a development accelerator.

Binders suitable for the photothermographic material of the present invention are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic, polyvinyl alcohol, and hydroxyethyl cellulose. , Cellulose acetate, cellulose acetate butyrate, polyvinylpyrrolidone, casein, starch, vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylate ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic ester, styrene , A compound comprising a polymer or copolymer containing ethylenically unsaturated monomers such as butadiene, ethylene, vinyl butyral, vinyl acetal and vinyl ether as constituent units, Down resins, various rubber resins. In addition, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicone resin, epoxy-polyamide resin, polyester resin and the like can be mentioned. These resins are described in detail in "Plastic Handbook" published by Asakura Shoten. Typical examples thereof include polyvinyl chloride, copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinylacetals (for example, polyvinylformal and polyvinylbutyral), polyesters, and polyurethane. , Phenoxy resin, polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetate, cellulose esters, polyamides and the like. It may be hydrophilic or non-hydrophilic.

Among these, the preferred binder for the photosensitive layer of the photothermographic material according to the present invention is polyvinyl acetal, and the particularly preferred binder is polyvinyl butyral. Details will be described later. Further, for non-photosensitive layers such as an overcoat layer and an undercoat layer, particularly a protective layer and a backcoat layer, polymers having a higher softening temperature, such as cellulose esters, especially triacetyl cellulose, and a polymer such as cellulose acetate butyrate. preferable. In addition, if necessary, the above binders may be used in combination of two or more. The binder (representing M is a hydrogen atom or an alkali metal _{salt,) -COOM, -SO 3 M,} -OSO 3 M, -P = O (OM) 2, -O-P = O (OM) 2,, At least one polar group selected from -N (R) ₂ , -N ⁺ (R) ₃ (R represents a hydrocarbon group), an epoxy group, -SH, -CN and the like is copolymerized or added. it is preferable to use those introduced, in particular -SO ₃ M, -OSO ₃ M, is preferred. The amount of such a polar group is from 10 ^-1 to 10 ^-8 mol / g, preferably from 10 ^-2 to 10 ^-6 mol / g.

Such a binder is used in a range effective to function as a binder. Effective ranges can be readily determined by one skilled in the art. For example, as an index when at least the organic silver salt is retained in the image forming layer, the ratio of the binder to the organic silver salt is preferably from 15: 1 to 1: 2, and particularly preferably from 8: 1 to 1: 1. . That is, the amount of the binder in the image forming layer is preferably 1.5 to 6 g / m ² . More preferably, it is 1.7 to 5 g / m ² . If it is less than 1.5 g / m ² , the density of the unexposed portion will increase significantly and may not be usable.

バ イ ン ダ ー The glass transition temperature Tg of the binder used in the present invention is preferably from 70 ° C to 105 ° C. Tg can be determined by measuring with a differential scanning calorimeter, and the intersection between the baseline and the slope of the endothermic peak is defined as the glass transition point.

In the present invention, the glass transition temperature (Tg) is determined by a method described in Brand Polymer, et al., “Polymer Handbook”, pages III-139 to III-179 (1966, Wiley & Sun). .

Ｔ The Tg when the binder is a copolymer resin is determined by the following equation.

Tg _{(copolymer) (℃) = 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 It represents the Tg (° C.) of the obtained homopolymer.

精度 The accuracy of Tg calculated according to the above equation is ± 5 ° C.

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

The binder of 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 there.

The polymer or copolymer containing the above-mentioned ethylenically unsaturated monomer as a constitutional unit will be described in more detail.As the ethylenically unsaturated monomer as a constitutional unit of the polymer, alkyl acrylates, aryl acrylates, Methacrylic acid alkyl esters, methacrylic acid aryl esters, cyanoacrylic acid alkyl esters, cyanoacrylic acid aryl esters, and the like, and the alkyl group and the aryl group thereof may be substituted or unsubstituted. Well, specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, hexyl, cyclohexyl, benzyl, chlorobenzyl, octyl, stearyl, sulfopropyl, N -Ethyl- Phenylaminoethyl, 2- (3-phenylpropyloxy) ethyl, dimethylaminophenoxyethyl, furfuryl, tetrahydrofurfuryl, phenyl, cresyl, naphthyl, 2-hydroxyethyl, 4-hydroxybutyl, triethylene glycol, dipropylene glycol, 2-methoxyethyl, 3-methoxybutyl, 2-acetoxyethyl, 2-acetoacetoxyethyl, 2-ethoxyethyl, 2-iso-propoxyethyl, 2-butoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- (2-ethoxyethoxy) ethyl, 2- (2-butoxyethoxy) ethyl, 2-diphenylphosphorylethyl, ω-methoxypolyethylene glycol (additional mole number n = 6), allyl, dimethylaminoethyl methyl chloride salt and the like. be able to.

In addition, the following monomers can be used. Vinyl esters (for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate, etc.); N -Substituted acrylamides, N-substituted methacrylamides and acrylamide, methacrylamide (N-substituents include methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl, benzyl, hydroxymethyl, methoxyethyl, dimethylaminoethyl, Olefins (e.g., dicyclopentadiene, ethylene); phenyl, dimethyl, diethyl, β-cyanoethyl, N- (2-acetoacetoxyethyl), diacetonyl, etc. Propylene, 1-butene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene and the like; styrenes: for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, tert-butylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinyl benzoate, etc .; vinyl ethers (for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether) , Dimethylaminoethyl vinyl ether, etc.); N-substituted maleimides (as N-substituents, methyl, ethyl, propyl, butyl, tert. -Butyl, cyclohexyl, benzyl, n-dodecyl, phenyl, 2-methylphenyl, 2,6-diethylphenyl, 2-chlorophenyl, etc.); and butyl crotonate, hexyl crotonate, Dimethyl itaconate, dibutyl itaconate, diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, glycidyl acrylate, glycidyl methacrylate , N-vinyloxazolidone, N-vinylpyrrolidone, acrylonitrile, methacrylonitrile, methylenemalononitrile, vinylidene chloride and the like.

特 に Among these, particularly preferred examples include alkyl methacrylates, aryl methacrylates, and styrenes. Among such polymer compounds, it is preferable to use a polymer compound having an acetal group. 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, and 2,828, No. 204 and British Patent No. 771,155.

As the polymer compound having an acetal group, a compound represented by the following general formula (V) is particularly preferable.

In the formula, R ₁₁ represents an unsubstituted alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, and is preferably a group other than the aryl group. R ₁₂ represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group, —COR ₁₃ or —CONHR ₁₃ . R ₁₃ has the same meaning as R ₁₁ .

The unsubstituted alkyl group represented by R ₁₁ , R ₁₂ and R ₁₃ preferably has 1 to 20 carbon atoms, and particularly preferably has 1 to 6 carbon atoms. These may be linear or branched, and are preferably linear alkyl groups. Such unsubstituted alkyl groups include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-amyl group, t-amyl group, n -Hexyl group, cyclohexyl group, n-hepsyl group, n-octyl group, t-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-dodecyl group, n-octadecyl group and the like. Is particularly preferably a methyl group or a propyl group.

The unsubstituted aryl group preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group. Examples of the group that can be substituted for the above-mentioned alkyl group and aryl group include an alkyl group (for example, a methyl group, an n-propyl group, a t-amyl group, a t-octyl group, an n-nonyl group, a dodecyl group, etc.), an aryl group (E.g., phenyl group), nitro group, hydroxyl group, cyano group, sulfo group, alkoxy group (e.g., methoxy group, etc.), aryloxy group (e.g., phenoxy group, etc.), acyloxy group (e.g., acetoxy group, etc.), Acylamino group (eg, acetylamino group), sulfonamide group (eg, methanesulfonamide group), sulfamoyl group (eg, methylsulfamoyl group), halogen atom (eg, fluorine atom, chlorine atom, bromine atom) ), A carboxy group, a carbamoyl group (eg, a methylcarbamoyl group), an alkoxycarbonyl group (eg, Aryloxycarbonyl group), a sulfonyl group (e.g., methyl sulfonyl group). When two or more substituents are present, they may be the same or different. The total carbon number of the substituted alkyl group is preferably 1 to 20, and the total carbon number of the substituted aryl group is preferably 6 to 20.

As R ₁₂ , —COR ₁₃ (R ₁₃ is an alkyl group or an aryl group) and —CONHR ₁₃ (R ₁₃ is an aryl group) are preferable. a, b, and c are values in which the mass of each repeating unit is represented by mol (mol)%, a is 40 to 86 mol%, b is 0 to 30 mol%, and c is 0 to 60 mol%. In the range, a + b + c = 100 mol%, and particularly preferably, a is in the range of 50 to 86 mol%, b is 5 to 25 mol%, and c is 0 to 40 mol%. Each of the repeating units having the respective composition ratios of a, b, and c may be composed of only the same unit or different units.

The polymer compound represented by the general formula (V) can be synthesized by a general synthesis method described in “Vinyl acetate resin” edited by Ichiro Sakurada (Polymer Chemistry Publishing Association, 1962).

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. Further, it is preferable that the polyurethane molecule has at least one OH group at each terminal, that is, two or more OH groups in total. Since the OH group forms a three-dimensional network structure by crosslinking with polyisocyanate as a curing agent, it is preferable to include a large number of OH groups in the molecule. In particular, it is preferable that the OH group is located at the molecular terminal because the reactivity with the curing agent is high. The polyurethane preferably has three or more OH groups at the molecular terminals, particularly preferably four or more. In the present invention, when polyurethane is used, the glass transition temperature is preferably 70 to 105 ° C, the elongation at break is 100 to 2000%, and the stress at break is preferably 0.5 to 100 N / mm ² .

These high molecular compounds (polymers) may be used alone or as a mixture of two or more. The above polymer is used as a main binder in the image forming layer of the present invention. The term "main binder" as used herein means "a state in which the polymer accounts for 50% by mass or more of the total binder in the image forming layer". Therefore, other polymers may be blended and used in a range of less than 50% by mass of the total binder. These polymers are not particularly limited as long as they are solvents in which the polymer of the present invention is soluble. More preferably, polyvinyl acetate, polyacrylic resin, urethane resin and the like can be mentioned.

に お い て In the present invention, the image forming layer may contain an organic gelling agent. The organic gelling agent referred to here is, for example, a function of imparting a yield value to the system by adding it to an organic liquid, such as a polyhydric alcohol, so as to eliminate or reduce the fluidity of the system. A compound having the following formula:

好 ま し い In the present invention, it is also a preferred embodiment that the coating solution for the image forming layer contains a polymer latex dispersed in water. In this case, it is preferable that 50% by mass or more of the total binder in the coating solution for the image forming layer is a polymer latex dispersed in an aqueous solution.

When the image forming layer according to the present invention contains a polymer latex, it is preferable that 50% by mass or more of all binders in the image forming layer is a polymer latex, more preferably 70% by mass or more.

「The“ polymer latex ”according to the present invention is a polymer in which a water-insoluble hydrophobic polymer is dispersed as fine particles in a water-soluble dispersion medium. The dispersion state is such that the polymer is emulsified in a dispersion medium, emulsion-polymerized, micelle-dispersed, or partially dispersed in polymer molecules and molecular chains themselves are molecularly dispersed. Any of them may be used.

(4) The average particle size of the dispersed particles is preferably from 1 to 50,000 nm, more preferably from about 5 to 1,000 nm. There is no particular limitation on the particle size distribution of the dispersed particles, and they may have a wide particle size distribution or a monodispersed particle size distribution.

ポ リ マ ー As the polymer latex according to the present invention, a so-called core / shell type latex other than a polymer latex having a normal uniform structure may be used. In this case, it may be preferable to change the glass transition temperature of the core and the shell. The minimum film forming temperature (MFT) of the polymer latex according to the present invention is preferably from -30 to 90C, more preferably from about 0 to 70C. Further, a film-forming auxiliary may be added to control the minimum film-forming temperature. The film-forming assistant used in the present invention is an organic compound (usually an organic solvent) which is also called a plasticizer and lowers the minimum film-forming temperature of the polymer latex. Issuance (1970)) ".

ポ リ マ ー Examples of the polymer used for the polymer latex include acrylic resin, vinyl acetate resin, polyester resin, polyurethane resin, rubber-based resin, vinyl chloride resin, vinylidene chloride resin, polyolefin resin, 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 usually from 5,000 to 1,000,000, preferably from about 10,000 to 100,000 in number average molecular weight. If the molecular weight is too small, the mechanical strength of the photosensitive layer is insufficient, and if it is too large, the film-forming properties are poor, which is not preferable.

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

Specific examples of the polymer latex include methyl methacrylate / ethyl acrylate / methacrylic acid copolymer latex, methyl methacrylate / 2-ethylhexyl acrylate / styrene / acrylic acid copolymer latex, styrene / butadiene / acrylic acid copolymer latex, and styrene / butadiene / latex. Latex of divinylbenzene / methacrylic acid copolymer, latex of methyl methacrylate / vinyl chloride / acrylic acid copolymer, latex of vinylidene chloride / ethyl acrylate / acrylonitrile / methacrylic acid copolymer and the like can be mentioned.

ポ リ マ ー These polymers may be used alone or as a blend of two or more as necessary. As the polymer species of the polymer latex, those containing about 0.1 to 10% by mass of a carboxylic acid component such as an acrylate or methacrylate component are preferable.

If necessary, hydrophilic polymers such as gelatin, polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, and hydroxypropylmethylcellulose may be added in a range of 50% by mass or less of the whole binder. The addition amount of these hydrophilic polymers is preferably 30% by mass or less of the total binder in the photosensitive layer.

In the preparation of the coating solution for the image forming layer according to the present invention, the order of addition of the organic silver salt and the aqueous dispersed polymer latex may be added first or may be added simultaneously, Preferably, the polymer latex is later.

It is preferable that an organic silver salt and further a reducing agent are mixed before the addition of the polymer latex. In addition, in the present invention, after mixing the organic silver salt and the polymer latex, if the temperature for aging is too low, the coated surface state is impaired, and if it is too high, there is a problem that fogging increases. It is preferable to age at 30 ° C. to 65 ° C. for the following time. Further, the aging is preferably performed at 35 ° C to 60 ° C, particularly preferably at 35 ° C to 55 ° C. In order to maintain the temperature in this manner, it is only necessary to keep the temperature of the coating solution preparation tank or the like.

The application of the coating solution for the image forming layer according to the present invention is preferably performed by mixing an organic silver salt and an aqueously dispersed polymer latex, and then using a coating solution that has passed 30 minutes to 24 hours, and more preferably, after mixing. , 60 minutes to 12 hours, and particularly preferably, a coating solution after 120 minutes to 10 hours.

Here, “after mixing” refers to a state after the organic silver salt and the polymer latex dispersed in water are added and the added materials are uniformly dispersed.

(4) In the present invention, it is preferable to use a crosslinking agent for the binder, since the film becomes better and unevenness in development is reduced. Further, it also has an effect of suppressing fogging during storage and suppressing generation of printout silver after development.

Examples of the cross-linking agent used in the present invention include various cross-linking agents conventionally used for photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethylene-imine-based and vinyl-based resins described in JP-A-50-96216. Sulfone-based, sulfonate-based, acryloyl-based, carbodiimide-based, and silane compound-based cross-linking agents can be used. Preferred are the following isocyanate-based compounds, silane compounds, epoxy compounds, or acid anhydrides.

イ ソ シ ア ネ ー ト The isocyanate-based and thioisocyanate-based cross-linking agents represented by the following general formula (2), which is one of the preferable ones, will be described.

General formula (2)
X ₂ = C = NL- (N = C = X ₂ ) _v
In the formula, v is 1 or 2, L is an alkylene, alkenylene, aryl group or alkylaryl group, represents a v + 1-valent linking group, and X ₂ represents an oxygen or sulfur atom.

In the compound represented by the general formula (2), the aryl ring of the aryl group may have a substituent. Examples of preferred substituents are selected from halogen atoms (eg, bromine or chlorine atoms), hydroxy, amino, carboxyl, alkyl and alkoxy groups.

The isocyanate-based crosslinking agent is an isocyanate having at least two isocyanate groups and an adduct thereof (adduct). More specifically, aliphatic diisocyanates and 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 diisocyanates of these isocyanates. Adducts with polyalcohols may be mentioned.

As specific examples, the isocyanate compounds described on pages 10 to 12 of JP-A-56-5535 can be used.

The adduct of an isocyanate and a polyalcohol has a particularly high ability to improve interlayer adhesion and to prevent delamination of the layer, image displacement and generation of bubbles. Such isocyanates may be located 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), the photosensitive layer side of the support such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer It can be added to any layer, and can be added to one or more of these layers.

化合物 As the thioisocyanate-based crosslinking agent that can be used in the present invention, a compound having a thioisocyanate structure corresponding to the above isocyanates is also useful.

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

The isocyanate compound and the thioisocyanate compound that can be contained in the present invention are preferably compounds that function as the above-mentioned crosslinking agent. In the above general formula, v is zero (0), that is, when the functional group is one, Good results can be obtained with only one compound.

シ ラ ン Examples of silane compounds that can be used as a crosslinking agent in the present invention include compounds represented by general formulas (1) to (3) disclosed in JP-A-2001-264930.

エ ポ キ シ The epoxy compound that can be used as a crosslinking agent in the present invention may be any compound having at least one epoxy group, and there is no limitation on the number, molecular weight, etc. of the epoxy group. 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, oligomer, polymer and the like, 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 a homopolymer or a copolymer, and a particularly preferred range of the number average molecular weight Mn is 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.

-CO-O-CO-
The acid anhydride used in the present invention only needs to have at least one such acid anhydride group, and there is no limitation on the number, molecular weight, and the like of the acid anhydride groups.

The above epoxy compounds and acid anhydrides may be used alone or in combination of two or more. 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.

In the present invention, an epoxy compound or an acid anhydride can be added to an optional layer on the photosensitive layer side of the support such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, and an undercoat layer. It can be added to one layer or two or more layers.

効果 In the present invention, the effect of the present invention can be further enhanced by using a silver saving agent as a compound capable of reducing the amount of silver required for obtaining a certain silver image density.

There are various possible mechanisms for the function of reducing the required amount of silver, but a compound having a function of improving the covering power of developed silver is preferable. Here, the covering power of the developed silver means an optical density per unit amount of silver.

Examples of the silver saving agent include a hydrazine derivative compound represented by the following general formula (H), a vinyl compound represented by the following general formula (G), and a quaternary onium compound represented by the following general formula (P). Preferred examples are given.

In the general formula (H), A ₀ represents an aliphatic group, an aromatic group, a heterocyclic group or a -G ₀ -D ₀ group which may have a substituent, and B ₀ represents a blocking group. , A ₁ and A _{2 each} represent a hydrogen atom, or one represents a hydrogen atom and the other represents an acyl group, a sulfonyl group or an oxalyl group. Here, G ₀ is a —CO— group, a —COCO— group, a —CS— group, a —C (＝ NG ₁ D ₁ ) — group, a —SO— group, a —SO ₂ — group, or a —P (O) ( G ₁ represents a D ₁ ) — group, G ₁ represents a mere bond, —O—, —S—, or —N (D ₁ ) —, and D ₁ represents an aliphatic group, an aromatic group, a complex Represents a ring group or a hydrogen atom, and when a plurality of D ₁ are present in a molecule, they may be the same or different. D ₀ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group. Preferred examples of D ₀ include a hydrogen atom, an alkyl group, an alkoxy group, and an amino group.

In the general formula (H), the aliphatic group represented by A ₀ preferably has 1 to 30 carbon atoms, particularly preferably a straight-chain, branched or cyclic alkyl group having 1 to 20 carbon atoms. Examples include a methyl group, an ethyl group, a t-butyl group, an octyl group, a cyclohexyl group, and a benzyl group. These are further substituted with suitable substituents (for example, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a sulfoxy group). Group, sulfonamide group, sulfamoyl group, acylamino group, ureido group, etc.).

In the general formula (H), the aromatic group represented by A ₀ is preferably a monocyclic or condensed-ring aryl group, for example, a benzene ring or a naphthalene ring, and the heterocyclic group represented by A ₀ Nitrogen, sulfur, a heterocyclic ring containing at least one heteroatom selected from oxygen atoms is preferred, such as a pyrrolidine ring, an imidazole ring, a tetrahydrofuran ring, a morpholine ring, a pyridine ring, a pyrimidine ring, a quinoline ring. Examples include a thiazole ring, a benzothiazole ring, a thiophene ring, and a furan ring. Aromatic groups A _0, heterocyclic group or -G ₀ -D ₀ group may have a substituent. Particularly preferred as A ₀ are an aryl group and a —G ₀ -D ₀ group.

In the general formula (H), A ₀ preferably contains at least one of a diffusion-resistant group or a silver halide adsorption group. As the diffusion-resistant group, a ballast group commonly used in immobile photographic additives such as couplers is preferable. As the ballast group, a photographically inactive alkyl group, alkenyl group, alkynyl group, alkoxy group, phenyl group And a phenoxy group, an alkylphenoxy group and the like, and the total number of carbon atoms in the substituent is preferably 8 or more.

In the general formula (H), the thiourea, thiourethane group, mercapto group, thioether group, thione group, heterocyclic group, thioamide heterocyclic group, mercapto heterocyclic group or And the adsorbing group described in JP-A-90439.

In the general formula (H), B ₀ represents a blocking group, preferably -G ₀ -D ₀ group, and G ₀ represents -CO- group, -COCO- group, -CS- group, -C (= NG ₁ D ₁ )-, -SO-, -SO _2-, or -P (O) (G ₁ D ₁ )-. Preferable G ₀ includes a —CO— group and a —COCO— group, G ₁ represents a mere bond, —O— group, —S— group or —N (D ₁ ) — group, and D ₁ represents a fatty acid. A group represents an aromatic group, an aromatic group, a heterocyclic group or a hydrogen atom. When a plurality of D ₁ are present in a molecule, they may be the same or different. D ₀ represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an amino group, an alkoxy group, an aryloxy group, an alkylthio group, or an arylthio group, and preferred D ₀ is a hydrogen atom, an alkyl group, an alkoxy group, And an amino group. A ₁ and A ₂ are both hydrogen atoms, or one is a hydrogen atom and the other is an acyl group (acetyl group, trifluoroacetyl group, benzoyl group, etc.), a sulfonyl group (methanesulfonyl group, toluenesulfonyl group, etc.), or an oxalyl group (Such as an ethoxalyl group).

化合物 The compounds represented by the general formula (H) can be easily synthesized by a known method. For example, it can be synthesized with reference to U.S. Patent Nos. 5,464,738 and 5,496,695.

Other hydrazine derivatives that can be preferably used include compounds H-1 to H-29 described in U.S. Pat. No. 5,545,505, columns 11 to 20, and columns 9 to 11 in U.S. Pat. No. 5,464,738. Compounds 1 to 12 described above. These hydrazine derivatives can be synthesized by a known method.

In the general formula (G), X ₂₁ and R ₂₁ are represented in the form of cis, but the general formula (G) also includes the form of X ₂₁ and R ₂₁ in a trans form. This is the same in the structural representation of a specific compound.

In the general formula (G), X ₂₁ represents an electron-withdrawing group, and W ₂₁ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a halogen atom, an acyl group, a thioacyl group, an oxalyl group. , Oxyoxalyl, thiooxalyl, oxamoyl, oxycarbonyl, thiocarbonyl, carbamoyl, thiocarbamoyl, sulfonyl, sulfinyl, oxysulfinyl, thiosulfinyl, sulfamoyl, oxysulfinyl, thiosulfinyl Group, sulfinamoyl group, phosphoryl group, nitro group, imino group, N-carbonylimino group, N-sulfonylimino group, dicyanoethylene group, ammonium group, sulfonium group, phosphonium group, pyrylium group and immonium group.

R ₂₁ represents a halogen atom, a hydroxyl group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, an alkenyloxy group, an acyloxy group, an alkoxycarbonyloxy group, an aminocarbonyloxy group, a mercapto group, an alkylthio group, an arylthio group, a heterocyclic thio group. Organic or inorganic salts (eg, sodium salt, potassium salt, silver salt, etc.) of a group, alkenylthio group, acylthio group, alkoxycarbonylthio group, aminocarbonylthio group, hydroxyl group or mercapto group, amino group, alkylamino group A cyclic amino group (for example, a pyrrolidino group), an acylamino group, an oxycarbonylamino group, a heterocyclic group (for example, a 5- to 6-membered nitrogen-containing heterocycle such as a benztriazolyl group, an imidazolyl group, a triazolyl group, or a tetrazolyl group) , Ureido group, sulfone It represents a de group. X ₂₁ and W ₂₁ , and X ₂₁ and R ₂₁ may be bonded to each other to form a cyclic structure. Examples of the ring formed by X ₂₁ and W ₂₁ include pyrazolone, pyrazolidinone, cyclopentanedione, β-ketolactone, β-ketolactam and the like.

化合物 Examples of compounds preferably used in the present invention are shown below.

In the general formula (P), Q represents a nitrogen atom or a phosphorus atom, R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ each represent a hydrogen atom or a substituent, and X ₃₁ ⁻ represents an anion. Incidentally, R _{31 to} R ₃₄ may be connected to each other to form a ring.

Examples of the substituent represented by R _{31 to} R ₃₄ include an alkyl group (methyl group, ethyl group, propyl group, butyl group, hexyl group, cyclohexyl group, etc.), an alkenyl group (allyl group, butenyl group, etc.), an alkynyl group (Propargyl group, butynyl group, etc.), aryl group (phenyl group, naphthyl group, etc.), heterocyclic group (piperidinyl group, piperazinyl group, morpholinyl group, pyridyl group, furyl group, thienyl group, tetrahydrofuryl group, tetrahydrothienyl group, Sulfolanyl group), an amino group and the like.

Examples of the ring that can be formed by linking R _{31 to} R ₃₄ include a piperidine ring, morpholine ring, piperazine ring, quinuclidine ring, pyridine ring, pyrrole ring, imidazole ring, triazole ring, tetrazole ring, and the like.

The groups represented by R _{31 to} R ₃₄ may have a substituent such as a hydroxyl group, an alkoxy group, an aryloxy group, a carboxyl group, a sulfo group, an alkyl group, and an aryl group. As R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ , a hydrogen atom and an alkyl group are preferred.

X ₃₁ ^- as an anion represented by the halogen ion, sulfate ion, nitrate ion, acetate ion, and inorganic and organic anions, such as p- toluenesulfonic acid ion.

The quaternary onium compound can be easily synthesized according to a known method. For example, the tetrazolium compound can be synthesized as described in Chemical Reviews vol. 55 p. 335-483 can be referred to. The amount of the silver saving agent is in the range of 10 ^-5 to 1 mol, preferably 10 ^{-4 to} 5 × 10 ^-1 mol, per 1 mol of the organic silver salt.
In the present invention, at least one of the silver saving agents is preferably a silane compound.

In the present invention, the silane compound used as a silver saving agent is preferably an alkoxysilane compound having two or more primary or secondary amino groups or a salt thereof as described in JP-A-2003-5324. .

Here, having two or more primary or secondary amino groups means that two or more primary amino groups only, two or more secondary amino groups only, and one primary amino group and one secondary amino group each. Including the above, a salt of an alkoxysilane compound refers to an adduct of an alkoxysilane compound with an inorganic or organic acid capable of forming an onium salt with an amino group.

Examples of such an alkoxysilane compound or a salt thereof include those described below. In the present invention, an alkoxysilane compound having two or more intramolecular primary or secondary amino groups or a salt thereof Is not limited to these compounds.

に お い て In these compounds, the alkoxy group forming an alkoxysilyl is preferably an alkoxy group composed of a saturated hydrocarbon, and more preferably a methoxy group, an ethoxy group, or an isopropoxy group because they have more excellent storage stability. Further, for the purpose of reducing sensitivity fluctuation due to storage conditions before thermal development, a compound having no unsaturated hydrocarbon group in the molecule is more preferable. These alkoxysilane compounds or salts thereof may be used alone or in combination of two or more.

It is preferable that the image forming layer contains a Schiff base formed by a dehydration condensation reaction between an alkoxysilane compound having at least one primary amino group and a ketone compound.

(5) By using such a Schiff base, silver can be saved, and an image having low fog, little sensitivity fluctuation, and extremely low gamma can be obtained irrespective of storage conditions before thermal development. Further, since the primary amine portion is blocked in advance, when a ketone-based solvent is used when preparing an image forming layer forming coating solution described later, sensitivity variation due to aging over time after preparing the coating solution is suppressed. be able to.

The ketone compound used for forming the above-mentioned alkoxysilane compound and the Schiff base can be used without any particular limitation, but has a boiling point of 150 due to the problem of odor generated when an image is formed by an image forming method described later. C. or less, more preferably 100.degree. C. or less.

Such a Schiff base is preferably a Schiff base formed by a dehydration condensation reaction between an alkoxysilane compound having one or more primary amino groups and a ketone compound.

Of the above compounds, for the purpose of saving silver, a Schiff base having one or more secondary amino groups in the molecule is more preferable. These Schiff bases may be used alone or in combination of two or more.

When an alkoxysilane compound or a salt thereof or a Schiff base is added to the image forming layer as a silver saving agent, it is preferably added in the range of usually 0.00001 to 0.05 mol per mol of silver. . The same applies to the case where both an alkoxysilane compound or a salt thereof and a Schiff base are added to the image forming layer.

However, if the addition amount of the above-mentioned alkoxysilane compound or Schiff base to 1 mol of silver is slightly increased, the image density of an unexposed portion formed by an image forming method described later may be increased. Therefore, in order to alleviate the dependence of the added amount of the added alkoxysilane compound or Schiff base on 1 mol of silver, an isocyanate compound having two or more isocyanate groups in the molecule is further added to the image forming layer. preferable. As the isocyanate compound, the isocyanate compound used as the above-mentioned crosslinking agent can be used.

(4) In order to adjust the characteristics of the photothermographic material of the present invention, a fog prevention and image stabilizer can be further used.

When a reducing agent having a proton such as bisphenols or sulfonamidophenols is mainly used as the reducing agent, the reducing agent can be inactivated by generating active species capable of extracting these hydrogens. Preferably, a compound is contained. Preferably, as the colorless photo-oxidizable substance, a compound capable of generating a free radical as a reactive species upon exposure is preferable.

Accordingly, any compound having these functions may be used, but an organic free radical comprising a plurality of atoms is preferable. A compound having any structure may be used as long as it has such a function and does not cause any particular adverse effect on the photothermographic material.

In addition, these free radical-generating compounds may be carbocyclic or heterocyclic in order to have such stability that the free radicals generated can be contacted with the reducing agent for a sufficient time to react with and inactivate them. Those having an aromatic group are preferred.

ビ Representative of these compounds are biimidazolyl compounds and iodonium compounds.

The addition amount of the biimidazolyl compound and the iodonium compound is in the range of 0.001 to 0.1 mol / m ² , and preferably in the range of 0.005 to 0.05 mol / m ² . The compound can be contained in any of the constituent layers in the light-sensitive material of the present invention, but is preferably contained near the reducing agent.

In the present invention, a compound that releases a halogen atom as an active species can be preferably used. Many compounds that can release a halogen atom as an active species are known, and a good effect can be obtained when used in combination.

具体 Specific examples of the compounds that generate these active halogen atoms include compounds of the following general formula (9).

In the general formula (9), Q ₅₁ represents an aryl group or a heterocyclic group. X ₅₁ , X ₅₂ and X ₅₃ represent a hydrogen atom, a halogen atom, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or an aryl group, at least one of which is a halogen atom. Y ₅₁ represents —C (＝ O) —, —SO— or —SO ₂ —.

The aryl group represented by Q ₅₁ may be monocyclic or condensed, and is preferably a monocyclic or bicyclic aryl group having 6 to 30 carbon atoms (eg, phenyl, naphthyl, etc.), more preferably It is a phenyl group or a naphthyl group, and more preferably a phenyl group.

The heterocyclic group represented by Q ₅₁ is a 3- to 10-membered saturated or unsaturated heterocyclic group containing at least one atom of N, O or S, which may be monocyclic, Further, a condensed ring may be formed with another ring.

The heterocyclic group is preferably a 5- or 6-membered unsaturated heterocyclic group optionally having a condensed ring, and more preferably a 5- or 6-membered aromatic heterocyclic ring optionally having a condensed ring. Group. More preferably, it is a 5- or 6-membered aromatic heterocyclic group which may have a condensed ring containing a nitrogen atom, and particularly preferably it may have a condensed ring containing 1 to 4 nitrogen atoms. And a 6-membered aromatic heterocyclic group. As the heterocycle in such a heterocyclic group, preferably, imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline , Cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, indolenine, tetrazaindene, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, Triazine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, Zoline, cinnoline, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, tetrazaindene, more preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole, quinoline, phthalazine, naphthyridine, They are quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, benzimidazole and benzthiazole, particularly preferably pyridine, thiadiazole, quinoline and benzthiazole.

Aryl group and heterocyclic group represented by Q ₅₁ may have other substitution groups _{-Y 51 -C (X 51) (} X 52) (X 53), preferably an alkyl group as a substituent , Alkenyl group, aryl group, alkoxy group, aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group, 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, heterocyclic group, more preferably an alkyl group, an aryl group, an alkoxy group, Aryloxy group, acyl group, acylamino group, alkoxycarbonyl An amino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, a ureido group, a phosphoric acid amide group, a halogen atom, a cyano group, a nitro group, or a heterocyclic group, and more preferably an alkyl group or an aryl group , An alkoxy group, an aryloxy group, an acyl group, an acylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, a halogen atom, a cyano group, a nitro group, and a heterocyclic group, and particularly preferably an alkyl group, an aryl group, and a halogen atom. It is.

X ₅₁ , X ₅₂ and X ₅₃ are preferably a halogen atom, a haloalkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, a heterocyclic group, more preferably a halogen atom, It is a haloalkyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a sulfonyl group, more preferably a halogen atom or a trihalomethyl group, and particularly preferably a halogen atom. Among the halogen atoms, a chlorine atom, a bromine atom and an iodine atom are preferred, a chlorine atom and a bromine atom are more preferred, and a bromine atom is particularly preferred.

Y ₅₁ is -C (= O) -, - SO -, - SO 2 - represents preferably -SO ₂ - is.

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 does not pose a problem, and is preferably at most 150% or less, more preferably at most 150% by weight, with respect to the compounds that do not generate active halogen radicals. It is preferably 100% or less.

Next, the antifoggant preferably used in the present invention will be described. Examples of the antifoggant preferably used in the present invention include compounds represented by the following formulas (A-6) to (A-8).

General formula (A-6) X ¹ -SO ₂ -SM ¹
General formula (A-7) X ¹ -SO ₂ -SY ¹
General formula (A-8) X ¹ -SO-SY ¹
In the formula, X ¹ and Y ¹ represent a substituted or unsubstituted alkyl group, aryl group, or heterocyclic group, and M ¹ represents a metal atom or an organic cation.

The aliphatic hydrocarbon group represented by X ¹ and Y ¹ is a linear, branched or cyclic alkyl group (preferably having 1 to 20, more preferably 1 to 16, more preferably 1 to 12), alkenyl Group (preferably having 2 to 20, more preferably 2 to 16, more preferably 2 to 12) alkynyl group (preferably having 2 to 20, more preferably 2 to 16, and still more preferably 2 to 12) And may have a substituent. The substituent of the aliphatic hydrocarbon group represented by X ¹ and Y ¹ is preferably an aryl group, an alkoxy group, or a heterocyclic group, and more preferably an aryl group or a heterocyclic group. The aliphatic hydrocarbon group represented by X ¹ and Y ¹ is preferably an alkyl group, and more preferably a chain alkyl group.

The aryl group represented by X ¹ and Y ¹ is preferably a monocyclic or condensed aryl group having 6 to 30 carbon atoms, more preferably a monocyclic or condensed aryl group having 6 to 20 carbon atoms. And, for example, phenyl, naphthyl and the like can be mentioned, and phenyl is particularly preferable. The aryl group represented by X ¹ and Y ¹ may have a substituent. Specific examples of the aryl group represented by X ¹ and Y ¹ include phenyl, 4-methylphenyl, naphthyl, benzoylamino, phenylsulfonylamino, phenylureido and the like.

The heterocyclic group represented by X ¹ and Y ¹ is a 3- to 10-membered saturated or unsaturated hetero ring containing at least one of N, O and S atoms, and these may be monocyclic. Alternatively, a condensed ring may be formed with another ring. The heterocyclic group is preferably a 5- or 6-membered heterocyclic group, more preferably a 5- or 6-membered heterocyclic group containing a nitrogen atom, even more preferably a 5- or 6-membered heterocyclic group containing 1 or 2 nitrogen atoms. Membered aromatic heterocyclic group. Specific examples of the heterocyclic group include, for example, imidazolyl, thiazolyl, oxazolyl, 1,2,4-triazolyl, 1,3,4-oxadiazolyl, 1,3,4-thiadiazolyl, pyridyl, quinolyl, tetrazolyl, benzimidazolyl, benz Oxazolyl, benzothiazolyl, benzotriazolyl, triazinyl and the like can be mentioned.

The metal atom represented by M ¹ is preferably an alkali metal atom such as a sodium ion or a potassium ion, and the organic cation is preferably an ammonium ion or a guanidine group.

Specific examples of the compounds represented by the general formulas (A-6) to (A-8) include, for example, compound examples a to j described in “0012” of JP-A-8-314059 and JP-A-7-209797. And the compound examples (1) to (44) described from p14 of JP-A-55-140833. Hereinafter, specific examples of the compound of the present invention are shown, but the present invention is not limited to these compounds.

Next, the compound represented by the following formula (A-9) will be described.

Formula _{(A-9) Z 7 -P} 7 -L 7 - (C = Q 7) -W 7
In the formula, P ₇ represents an oxygen atom, a sulfur atom or an NH group, Q ₇ represents an oxygen atom or a sulfur atom, W ₇ is an OH group, an OM group, an SH group, a SM group (M is a counter ion) or NH It represents ₂ group, L ₇ represents an alkylene group, Z ₇ represents an alkyl group, an aryl group or a heterocyclic group.

In the general formula (A-9), preferred examples of the substituent represented by-(C = Q ₇ ) -W ₇ include a carboxyl group, a carboxylate, a thiocarboxyl group, a thiocarboxylate, a dithiocarboxyl group, Thiocarboxylates and carbamoyl groups can be mentioned. When W ₇ is an OM group or an SM group (M represents a counter ion), examples of the counter ion include inorganic or organic ammonium ions (for example, ammonium ion, triethylammonium ion, and pyridinium ion), and alkali metal ions. (Eg, sodium ion, potassium ion), alkaline earth metal ion (eg, calcium ion, magnesium ion), and other metal ions (eg, aluminum ion, barium ion, zinc ion). An ionic polymer, or another organic compound having a reverse charge, or a metal complex ion (eg, hydroxopentaaquaaluminum (III) ion, tris (2,2'-bipyridine) iron (II) ion) can also be a counter ion. sell. Further, it may form an inner salt with another substituent in the molecule. Preferred are sodium ion, potassium ion, ammonium ion, triethylammonium ion and pyridinium ion, and more preferred are sodium ion, potassium ion and ammonium ion.

The length of the alkylene group represented by L ₇ is preferably 2 atomic to 1-4 atomic, more preferably 1. The alkylene group represented by L may further have a substituent. -CH ₂ Preferred examples _{-, - CH 2 CH 2 -} , - CH (CH 3) -, - CH (CH 2 CH 3) CH 2 - and the like. More preferred, -CH ₂ - is.

Alkyl group represented by Z ₇ is a straight-chain, branched or cyclic alkyl group or a combination thereof, preferably 1 to 40 carbon atoms, more preferably 1 to 30, more preferably from 1 to 25. For example, methyl, ethyl, allyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, sec-pentyl, isopentyl, tert-pentyl, hexyl Group, cyclohexyl group, octyl group, tert-octyl group, decyl group, undecyl group, dodecyl group, tridecyl group, pentadecyl group, nonadecyl group, icosyl group, docosyl group, 2-hexyldecyl group, 2-ethylhexyl group, 6- Examples thereof include a methyl-1- (3-methylhexyl) nonyl group and a benzyl group.

The alkyl group represented by Z ₇ may have a substituent, and the substituent may be any known group. For example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (including a N-substituted nitrogen-containing heterocyclic group, such as a morpholino group ), Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, imino group, imino group substituted with N atom, thiocarbonyl group, carbazoyl group, cyano group, thiocarbamoyl group, alkoxy group, aryloxy group, heterocyclic oxy group An acyloxy group, an (alkoxy or aryloxy) carbonyloxy group, a sulfonyloxy group, an acylamide group, a sulfonamide group, a ureido group, a thioureido group, an imide group, an (alkoxy or aryloxy) carbonylamino group, a sulfamoylamino group, Semi-carba Group, thiosemicarbazide group, (alkyl or aryl) sulfonyluureido group, nitro group, (alkyl or aryl) sulfonyl group, sulfamoyl group, group containing a phosphoric acid amide or a phosphoric ester structure, silyl group, carboxyl group or a salt thereof , A sulfo group or a salt thereof, a phosphate group, a hydroxy group, a quaternary ammonium group, and the like. These substituents may be further substituted with these substituents.

Examples of the alkyl group having a substituent represented by Z ₇ include an aryloxyalkyl group, an alkoxyalkyl group, a polyalkyleneoxyalkyl group (such as a hydroxyethoxyethyl group, an ethoxyethyl group, an ethoxyethoxyethyl group), and an alkylthioalkyl group (Such as an ethylthioethyl group).

The aryl group represented by Z ₇ is an aryl group or a monocyclic or condensed ring, preferably having 6 to 20 carbon atoms, more preferably 6 to 16, more preferably 6 to 10, a phenyl group or a naphthyl group preferable. The aryl group represented by Z ₇ may have a substituent, and any substituent may be used as long as it does not adversely affect photographic performance. For example, the same groups as the above-mentioned substituents of the alkyl group can be mentioned. The preferred substitution position of the substituent on the aryl group is at the 2-position, and it is preferable that the substituent can form a complex with silver ion together with P ₇ , Q ₇ or W ₇ . Preferred examples of the substituent and the substitution position include a 2-carboxy group, a 2-carbamoyl group, a 2-thiocarboxy group, and a 2-dithiocarboxyl group.

The heterocyclic group represented by Z ₇ is a 5- to 7-membered saturated or unsaturated monocyclic or condensed ring in which the heterocyclic ring contains at least one heteroatom selected from the group consisting of nitrogen, oxygen and sulfur atoms. Some are preferred. Examples of the hetero ring, preferably a pyridine ring, quinoline ring, isoquinoline ring, pyrimidine ring, pyrazine ring, pyridazine ring, phthalazine ring, triazine ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, benzoxazole ring, thiazole Ring, benzothiazole ring, imidazole ring, benzimidazole ring, thiadiazole ring, triazole ring, etc., more preferably pyridine ring, quinoline ring, pyrimidine ring, thiadiazole ring, benzothiazole ring, particularly preferably pyridine ring Quinoline ring and pyrimidine ring. The heterocyclic group represented by Z ₇ may have a substituent, and examples thereof include the same groups as the above-mentioned substituents of the alkyl group.

Z ₇ is preferably an optionally substituted phenyl group, a naphthyl group, a quinolyl group, a pyridyl group, a pyrimidyl group, a polyethyleneoxy group, more preferably a phenyl group, a substituted phenyl group, and particularly preferably , A 2-alkylphenyl group, a 2,4-dialkylphenyl group, a 2-carboxyphenyl group, a 2-carbamoylphenyl group, and a 2-thiocarboxyphenyl group. Further, as the substituent of Z _7, known and so-called ballast group in a photographic material, the adsorption group to silver halide may have a group which imparts water solubility. The substituents may combine to form a bis-type, tris-type, or tetrakis-type, or may be polymerized with each other to form a polymer.

Compounds represented by the general formula (A-9) include water or a suitable organic solvent such as alcohols (methanol, ethanol, propanol, fluorinated alcohol), ketones (acetone, methylethylketone), dimethylformamide, dimethylsulfoxide, It can be used by dissolving it in methylcellosolve or the like. Also, by the well-known emulsification dispersion method, dibutyl phthalate, tricresyl phosphate, oil such as glyceryl triacetate or diethyl phthalate, dissolved using an auxiliary solvent such as ethyl acetate or cyclohexanone, mechanically emulsified dispersion. Can be prepared and used. Alternatively, a powder of the compound represented by the general formula (A-9) may be dispersed in a suitable solvent such as water using a ball mill, a colloid mill, or ultrasonic waves by a method known as a solid dispersion method. it can.

The compound represented by formula (A-9) may be added to any layer on the image forming layer side of the support, but is preferably added to the image forming layer or a layer adjacent thereto. The addition amount of the compound represented by formula (A-9) is preferably in the range of 0.01 to 10 mmol / m ^2, more preferably 0.1 to 5 mmol / m ^2, even more preferably 0.2 to The range is ² mmol / m ² .

Specific examples of the compound represented by the general formula (A-9) include, for example, compounds (I-1) to (I-6) described in “0063” of JP-A-2001-13627, and (C-) described in “0066”. 1) to (C-3), and compounds (III-1) to (III-108) described in “0027” of JP-A-2002-90937. Preferred examples of the compound represented by Formula (A-9) are shown below, but the compounds of Formula (A-9) that can be used in the present invention are not limited thereto.

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 them in combination. Examples of the group that forms a hydrogen bond with a hydroxyl group or an amino group include a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, and a nitrogen-containing aromatic group. No. Among them, preferred are a phosphoryl group, a sulfoxide group, an amide group (provided that they have no> NH group and are blocked like> NR (R is a substituent other than H)), and a urethane group. (However, it has no> NH group and is blocked like> NR (R is a substituent other than H)), a ureido group (however, does not have a> NH group and has> It is a compound having NR (R is blocked like a substituent other than H).

特 に In the present invention, a particularly preferred hydrogen bonding compound is a compound represented by the following formula (A-10).

In Formula (A-10), R ₅ , R _6, and R ₇ each independently represent an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, or a heterocyclic group. It may be unsubstituted or have a substituent. When R ₅ , R ₆ and R ₇ have a substituent, examples of the substituent include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, An acyloxy group, an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, a phosphoryl group and the like are mentioned. Preferred substituents are an alkyl group or an aryl group such as a methyl group, an ethyl group, an isopropyl group, a t-butyl group, Examples include a t-octyl group, a phenyl group, a 4-alkoxyphenyl group, and a 4-acyloxyphenyl group.

As the alkyl group represented by R ₅ , R ₆ and R ₇ , a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, which is linear, branched, cyclic, or a combination thereof is preferable. Methyl, ethyl, butyl, octyl, dodecyl, isopropyl, t-butyl, t-amyl, t-octyl, cyclohexyl, 1-methylcyclohexyl, benzyl, phenethyl, 2- Phenoxypropyl group and the like. As an example of the aralkyl group, an aralkyl group having 7 to 27 carbon atoms is preferable, and examples thereof include a benzyl group, a phenethyl group, and a 2-phenoxypropyl group.

As the aryl group, a monocyclic or polycyclic substituted or unsubstituted aryl group having 6 to 20 carbon atoms is preferable, and a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group, a 4-t -Octylphenyl group, 4-anisidyl group, 3,5-dichlorophenyl group and the like. The alkoxy group is preferably a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, such as a straight-chain, branched-chain, cyclic or combination thereof, and is preferably a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, or a 2-ethylhexyl group. Examples include an oxy group, a 3,5,5-trimethylhexyloxy group, a dodecyloxy group, a cyclohexyloxy group, a 4-methylcyclohexyloxy group, a benzyloxy group and the like. As the aryloxy group, an aryloxy group having 6 to 20 carbon atoms is preferable, and examples thereof include a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, and a biphenyloxy group.

As the amino group, an amino group having 0 to 20 carbon atoms is preferable, and a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, And a methyl-N-phenylamino group.

The heterocyclic group is a 3- to 10-membered saturated or unsaturated heterocyclic group containing at least one of N, O and S atoms, which may be a monocyclic ring or a heterocyclic group. A condensed ring may be formed. Specific examples of the heterocycle in the heterocyclic group include, for example, pyrrolidine, piperidine, piperazine, morpholine, thiophene, furan, pyrrole, imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine , Thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzothiazole, benzoselenazole, indolenine, tetra Seinden and the like.

R ₅ and R ₆ , R ₆ and R _7, or R ₅ and R ₆ and R ₇ together can represent an optionally substituted monocyclic or polycyclic hydrocarbon group. As R _{5 to} R ₇ , an alkyl group, an aryl group, an alkoxy group, and an aryloxy group are preferable. From the viewpoint of the effects of the present invention, at least one of R _{5 to} R ₇ is preferably an alkyl group or an aryl group, and more preferably two or more are an alkyl group or an aryl group. Further, it is preferable that R _{5 to} R ₇ are the same group in that they can be obtained at low cost.

具体 Specific examples of the compound of the general formula (A-10) include, for example, compounds (II-1) to (II-40) described in “0061” to “0064” of JP-A-2002-90937. Specific examples are shown below, but the compounds that can be used in the present invention are not limited to these.

The compound represented by the general formula (A-10) can be used in a photothermographic material after being contained in a coating solution in the form of a solution, an emulsified dispersion, or a solid-dispersed fine particle dispersion, like the reducing agent. . The compound represented by the general formula (A-10) forms a hydrogen bonding complex with a compound having a phenolic hydroxyl group and an amino group in a solution state, and the compound represented by the general formula (A-10) is represented by the following formula: Depending on the combination with the compound to be prepared, the compound can be isolated in a crystalline state as a complex. It is particularly preferable to use the crystal powder isolated in this way as a solid dispersion fine particle dispersion in order to obtain stable performance. Further, a method in which a reducing agent and a compound represented by the general formula (A-10) are mixed in a powder form, and a suitable dispersant is used to form a complex at the time of dispersion with a sand grinder mill or the like can also be preferably used. The compound represented by formula (A-10) is preferably used in a range of 1 to 200 mol%, more preferably in a range of 10 to 150 mol%, and still more preferably 30 to 150 mol%, based on the reducing agent. It is in the range of 100 mol%.

In the present invention, vinyl sulfones (general formula (A-11)) and / or β-halo sulfones (general formula (A-12)) can be preferably used for improving fog stability.

General formula (A-11)
(CH ₂ = CH-SO ₂ ) _n11 -L ₁₁
General formula (A-12)
_{(X 11 CH 2 CH 2 -SO} 2) n11 -L 11
In the formula, X ₁₁ represents a halogen atom such as chlorine or bromine, n11 represents 1, 2, 3, or 4, and L ₁₁ represents an organic bonding group. The organic linking group may be, for example, an alkyl, alkene, aryl, or mixture of alkyl and aryl groups (e.g., alkaryl or aralkyl or arylalkyl groups known in the art) having no more than 20 carbon atoms. Another example of a linking group is found in the silver halide photographic patents cited above.

The aryl ring may have a substituent selected from the group consisting of halogen (eg, Br, Cl), hydroxy, amino, carboxy, alkyl, alkoxy. Where the term "group" is used to describe a substituent, substitution above this substituent is intended. For example, the alkyl group, an ether group _{(e.g., CH 3 -CH 2 -CH 2 -O} -CH 2 -), haloalkyl, nitro alkyl, carboxyalkyl, hydroxyalkyl, and the like sulfoalkyl. On the other hand, the term "alkyl" includes only hydrocarbons. Substituents that react with the active ingredient, such as very strong electron withdrawing or oxidizing substituents, are of course excluded as not being inert or harmless.

Vinyl sulfones and divinyl sulfones are described in the literature, for example, U.S. Pat. Nos. 2,994,611, 3,061,436, 3,132,945, 3,490,911 and 3,490,911. No. 3,527,807, No. 3,593,644, No. 3,642,486, No. 3,642,908, No. 3,839,042, No. 3,841,872 Nos. 3,957,882, 4,088,495, 4,108,848, 4,137,082, and 4,142,897. is there. These are also described in Belgian Patent 819,015 and U.S. Pat. No. 4,173,481. Specific examples include compounds VS-1 to VS-7 and compounds HS-1 to HS-5 described in “0013” of JP-A-6-208192. Specific examples of the above-mentioned vinylsulfone and β-halosulfone antifoggants which are preferably used in the present invention are listed below, but it should not be understood that the present invention is limited thereto.
(21) CH ₂ ＣＨCH—SO ₂ —CH (OH) —CH ₂ —SO ₂ —CH ＝ CH _{2
(22) CH 2 = CH-} SO 2 -CH 2 -CH 2 -O-CH = CH-SO 2 -CH = CH 2
_{(23) CH 2 = CH-} SO 2 -CH = CH-SO 2 -CH = CH 2
_{(24) CH 2 = CH-} SO 2 -CH 2 -O-CH 2 -SO 2 -CH = CH 2
_{(25) Cl-CH 2 -CH} 2 -SO 2 -CH 2 -SO 2 -CH 2 -CH 2 -Cl
_{(26) Br-CH 2 -CH} 2 -SO 2 -CH 2 -SO 2 -CH 2 -CH 2 -Br
_{(27) Cl-CH 2 -CH} 2 -SO 2 -CH 2 -O-CH 2 -SO 2 -CH 2 -CH 2 -Cl
The above antifoggant is generally used in an amount of at least 0.001 mol per mol of silver. Usually, the range is from 0.01 to 5 moles of compound per mole of silver, preferably from 0.02 to 0.6 moles per mole of silver.

In addition to the above compounds, the photothermographic material of the present invention may contain a compound conventionally known as an antifoggant, but produces the same reactive species as the above compounds. The compound may be a compound capable of preventing fog, or a compound having a different fog prevention mechanism. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. Nos. 3,874,946 and 4,756. , 999, JP-A-9-288328, and 9-90550. Further, examples of other antifoggants include compounds disclosed in U.S. Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981 and 631,176.

The photothermographic material of the present invention is for forming a photographic image by a heat development process, and contains a toning agent for adjusting the color tone of silver, if necessary, usually in a state dispersed in an (organic) binder matrix. Is preferred.

Examples of suitable toning agents used in the present invention are described in RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136 and 4,021,249. Disclosed, for example, include:

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

で は In the present invention, a fluorine-based surfactant represented by the following general formula (A-13) is used in order to improve film transportability and environmental suitability (accumulation in a living body) in a heat development processing apparatus.

Formula (A-13) (Rf- ( L 1) n1 -) p - (Y) m1 - (A) q
In the formula, Rf represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group containing no fluorine atom, Y represents a divalent to tetravalent linking group having no fluorine atom, A represents an anion group or a group comprising a salt thereof, n1 and m1 represent an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, n1 and m1 are not simultaneously 0.

In Formula (A-13), Rf represents a substituent containing a fluorine atom. Examples of the substituent containing a fluorine atom include an alkyl group having 1 to 25 carbon atoms and substituted with a fluorine atom (e.g., A fluorine atom-substituted methyl group, ethyl group, butyl group, octyl group, dodecyl group, octadecyl group or the like) or a fluorine atom-substituted alkenyl group (eg, a fluorine atom-substituted propenyl group, butenyl group, A nonenyl group and a dodecenyl group).

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 (eg, oxymethylene group, oxyethylene group, oxybutylene group, etc.), oxyalkyleneoxy group (eg, oxymethyleneoxy group, An oxyethyleneoxy group, an oxyethyleneoxyethyleneoxy group), a phenylene group, an oxyphenylene group, a phenyloxy group, an oxyphenyloxy group, or a group obtained by combining these groups.

A represents an anion group or a group consisting of a salt thereof, for example, a group consisting of a carboxylic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), a group consisting of a sulfonic acid group or a salt thereof (sodium salt, potassium salt) And a salt group or a salt thereof (sodium salt and potassium salt).

Y ₁ represents a trivalent or tetravalent linking group having no fluorine atom, for example, a trivalent or tetravalent linking group having no fluorine atom and constituted around a carbon atom or a nitrogen atom Atom group. n1 represents an integer of 0 or 1, and is preferably 1.

The fluorine-based surfactant represented by the general formula (A-13) 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, A compound having a fluorooctyl group and a perfluorooctadecyl group) and an alkenyl compound (e.g., a perfluorohexenyl group and a perfluorononenyl group), and a trivalent to hexavalent alkanol compound to which a fluorine atom is not introduced, An anion group (A) is further added to the compound (partially Rf-modified alkanol compound) obtained by addition reaction or condensation reaction with an aromatic compound or a hetero compound having 3 to 4 hydroxyl groups by, for example, sulfate esterification. It can be obtained by introducing.

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

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

好 ま し い The following are preferable specific compounds of the fluorine-based surfactant represented by the general formula (A-13).

は As a method for adding the fluorine-based surfactant represented by the general formula (A-13) of the present invention to a coating solution, it can be added according to a known addition method. That is, it can be added by dissolving in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, and polar solvents such as dimethyl sulfoxide and dimethylformamide. Further, fine particles of 1 μm or less can be dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion, and then added. Although many techniques have been disclosed as fine particle dispersion techniques, they can be dispersed according to these techniques. The fluorine-based surfactant represented by the general formula (A-13) is preferably added to the outermost protective layer.

The addition amount of the fluorine-based surfactant represented by the general formula (A-13) of the present invention is preferably from 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol per 1 m ² , and from 1 × 10 ⁻⁵ to 1 × 10 mol. ^-2 mol is particularly preferred. If the amount is less than the former range, the charging characteristics cannot be obtained. If the amount exceeds the former range, the humidity dependency is large and the storage stability under high humidity deteriorates.

In the photothermographic material of the invention, the average particle size of the matting agent contained in the outermost surface on the side having the image forming layer is Le (μm), and the average particle size of the matting agent contained in the outermost surface on the side having the backcoat layer is provided. When the diameter is Lb (μm), it is preferable that Lb / Le is 1.5 or more and 10 or less. By setting Lb / Le within this range, density unevenness during thermal development can be improved.

In the present invention, the object of the present invention and the surface roughness of the surface layer of the photothermographic material (even when a non-photosensitive layer is provided on the image forming layer side or on the side opposite to the image forming layer sandwiching the support) are provided. It is preferable to use an organic or inorganic powder as a matting agent for controlling the surface roughness. As the powder used in the present invention, it is preferable to use a powder having a Mohs hardness of 5 or more. As the powder, a known inorganic powder or organic powder can be appropriately selected and used. Examples of the inorganic powder include titanium oxide, barium sulfate, boron nitride, SnO ₂ , SiO ₂ , Cr ₂ O ₃ , α-Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, cerium oxide, corundum, Artificial diamond, garnet, garnet, mica, silica, silicon nitride, silicon carbide and the like can be mentioned. Examples of the organic powder include powders such as polymethyl methacrylate, polystyrene, and Teflon (R). Among these, preferred are 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. , SiO ₂ and α-Al ₂ O ₃ are preferred, and SiO ₂ is particularly preferred.

に お い て In the present invention, the powder is preferably surface-treated with a Si compound and / or an Al compound. The use of such a surface-treated powder can improve the surface condition of the uppermost layer. The content of Si and / or Al is preferably 0.1 to 10% by mass of Si and 0.1 to 10% by mass, more preferably 0.1 to 10% by mass, based on the powder. It is particularly preferable that 1 to 5% by mass, Al is 0.1 to 5% by mass, Si is 0.1 to 2% by mass, and Al is 0.1 to 2% by mass. Further, 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. In the present invention, the average particle diameter of the powder is the average diameter of the spherical powder, the average major axis length of the acicular powder, and the maximum diagonal length of the plate-like surface of the plate-like powder. Mean value, and can be easily obtained from measurement with an electron microscope.

有機 The above-mentioned 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 size 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. is there. The amount added is usually from 1.0 to 20% by mass, preferably from 2.0 to 15% by mass, more preferably from 3 to 10% by mass, based on the amount of the binder used in the outermost layer (the curing agent is included in the amount of the binder). 0.0 to 10% by mass. The average particle size of the organic or inorganic powder contained in the outermost layer on the side opposite to the photosensitive layer side with respect to the support is usually 2.0 to 15.0 μm, preferably 3.0 to 12.0 μm, More preferably, it is 4.0 to 10.0 μm. The amount of addition is usually 0.2 to 10% by mass, preferably 0.4 to 7% by mass, more preferably 0 to 10% by mass, based on the amount of binder used for the outermost layer (the curing agent is included in the amount of binder). 0.6 to 5% by mass.

粉末 Further, a powder having a variation coefficient of the particle size distribution of 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 dispersed in advance and applied, or a method in which the organic or inorganic powder is sprayed before the drying is completed after the application of the coating liquid. You may. When a plurality of types of powder are added, both methods may be used in combination.

Examples of the material of the support used in the photothermographic material according to the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (for example, aluminum), and the like. What can be processed into a flexible sheet or roll is suitable. Accordingly, as the support in the photothermographic material of the present invention, a plastic film (for example, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyamide film, a polyimide film, a cellulose triacetate film or a polycarbonate film) is used. In the present invention, a biaxially stretched polyethylene terephthalate film is particularly preferred. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

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

In particular, in the present invention, the surface protective layer on the backing layer side preferably contains a conductive metal oxide. Thus, it was found that the effects of the present invention (especially, transportability during thermal development processing) can be further improved. Here, the conductive metal oxide is a crystalline metal oxide particle, and generally includes those containing oxygen vacancies and those containing a small amount of heteroatoms forming a donor with respect to the metal oxide used. 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 include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O _{5, and the} like, or composite oxides thereof. ZnO, TiO ₂ and SnO ₂ are preferred. Examples of including heteroatoms include, for example, addition of Al, In or the like to ZnO, addition of Sb, Nb, P, a halogen element or the like to SnO ₂ , or addition of Nb, Ta or the like to TiO ₂ . Is effective. The addition amount of these different atoms is preferably in the range of 0.01 to 30 mol%, and particularly preferably 0.1 to 10 mol%. Further, a silicon compound may be added at the time of preparing the fine particles in order to improve fine particle dispersibility and transparency. The metal oxide fine particles used in the present invention have conductivity, and have a volume resistivity of 10 ⁷ Ωcm or less, particularly 10 ⁵ Ωcm or less. These oxides are described in JP-A-56-143431, JP-A-56-120519, and JP-A-58-62647. Further, as described in JP-B-59-6235, a conductive material in which the above-mentioned metal oxide is adhered to other crystalline metal oxide particles or fibrous materials (for example, 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, stability after dispersion is good and easy to use. Use of conductive particles having a size of 0.3 μm or less to minimize the light scattering property is very preferable because a transparent photosensitive material can be formed. When the conductive metal oxide is acicular or fibrous, the length is preferably 30 μm or less and the diameter is preferably 1 μm or less, and particularly preferably the length is 10 μm or less and the diameter is 0.3 μm or less. The diameter ratio is 3 or more. As the SnO _2, is also commercially available from Ishihara Sangyo Co., it can be used SNS10M, SN-100P, SN- 100D, FSS10M the like.

熱 The photothermographic material of the present invention has at least one photosensitive layer as an image forming layer on a support. Although only the image forming layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the image forming layer. For example, a protective layer is preferably provided on the image forming layer for the purpose of protecting the image forming layer, and prevents sticking between the heat developing materials or in the heat developing material roll on the opposite surface of the support. For this purpose, a back coat layer is provided. As a binder used for these protective layer or back coat layer, a glass transition point is higher than the image forming layer, and abrasion or a polymer that hardly deforms, for example, cellulose acetate, a polymer such as cellulose acetate butyrate, is a polymer of the binder. Selected from among them.

In addition, two or more image forming layers may be provided on one side of the support, or one or more layers may be provided on both sides of the support for gradation adjustment or the like.

In the photothermographic material according to the present invention, a filter layer is formed on the same side as or opposite to the image forming layer to control the amount or wavelength distribution of light transmitted through the image forming layer, or the image forming layer It is preferable to include a dye or a pigment.

As the dye used in the present invention, known compounds that absorb light in various wavelength ranges according to the color sensitivity of the heat-developable material can be used.

For example, when the heat-developable material according to the present invention is used as an image recording material using infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (the thiopyrylium squarylium dye in this publication) It is preferable to use a squarylium dye having a pyrylium nucleus (hereinafter referred to as a pyrylium squarylium dye), or a thiopyrylium croconium dye similar to the squarylium dye or a pyrylium croconium dye.

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

The photothermographic material of the present invention may be formed by preparing a coating solution obtained by dissolving or dispersing the above-described constituent layer materials in a solvent, applying a plurality of these coating solutions simultaneously and then performing a heat treatment. preferable. Here, “multi-layer coating at the same time” means that a coating solution for each constituent layer (for example, a photosensitive layer and a protective layer) is prepared, and when the coating solution is applied to a support, coating and drying are repeated for each layer individually. In other words, it means that each constituent layer can be formed in a state where the steps of simultaneously performing multi-layer coating and drying can be performed at the same time. That is, the upper layer is provided before the remaining amount of all the solvents in the lower layer becomes 70% by mass or less.

There is no particular limitation on the method of simultaneously applying multiple layers of each constituent layer, for example, using a known method such as a bar coater method, a curtain coat method, an immersion method, an air knife method, a hopper application method, or an extrusion application method. Can be. Of these, a pre-metering type coating method called an extrusion coating method is more preferable. The extrusion coating method does not volatilize on the slide surface unlike the slide coating method, and thus is suitable for precision coating and organic solvent coating. Although this coating method has been described on the side having the photosensitive layer, the same applies to the case where the backcoat layer is provided and the coating is performed together with the undercoating. Japanese Patent Application Laid-Open No. 2000-15173 describes in detail the simultaneous multilayer coating method for a heat developing material.

In the present invention, it is preferable to select an appropriate amount of silver to be applied according to the purpose of the photothermographic material. However, for the purpose of medical images, the amount is preferably 0.3 g / m ² or more and 1.5 g / m ² or more. / M ² or less, more preferably 0.5 g / m ² or more and 1.5 g / m ² or less. Of the coated silver amount, the amount derived from silver halide preferably accounts for 2 to 18% of the total silver amount, and more preferably 5 to 15%.

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

Further, the coating density of the non-photosensitive long-chain aliphatic carboxylate is 1 × 10 ⁻¹⁷ g or more and 1 × 10 ⁻¹⁷ g or more per silver halide grain having a particle size of 0.01 μm or more (equivalent sphere equivalent particle size). ^-15 g or less, preferably 1 × 10 ⁻¹⁶ g or more and 1 × 10 ⁻¹⁴ g or less.

When the coating is performed under the above-mentioned conditions, it is preferable from the viewpoint of the optical maximum density of the silver image per a fixed amount of silver applied, that is, the silver coating amount (covering power) and the color tone of the silver image. The result is obtained.

In the present invention, the photothermographic material preferably contains a solvent in the range of 5 to 1000 mg / m ² during development. It is more preferable to adjust so as to be 100 to 500 mg / m ² . Thereby, a photothermographic material having high sensitivity, low fog and high maximum density can be obtained.

Examples of the solvent include ketones such as acetone, methyl ethyl ketone, and isophorone; alcohols such as methyl alcohol, ethyl alcohol, i-propyl alcohol, cyclohexanol, and benzyl alcohol; ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and hexylene glycol. Glycols such as ethylene glycol monomethyl ether and diethylene glycol monoethyl ether; ethers such as i-propyl ether; esters such as ethyl acetate and butyl acetate; chlorides such as methylene chloride and dichlorobenzene. Hydrocarbons and the like. Other examples include water, formamide, dimethylformamide, toluidine, tetrahydrofuran, acetic acid and the like. 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 temperature conditions in a drying step after the coating step. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

熱 When storing the photothermographic material of the present invention, it is preferable to store and store the photothermographic material in a package in order to prevent the density from changing over time and the occurrence of fogging. The porosity in the package is preferably from 0.01 to 10%, and more preferably from 0.02 to 5%. Nitrogen sealing is performed so that the partial pressure of nitrogen in the package is at least 80%, preferably at least 90%. Is good.

熱 The photothermographic material of the present invention generally uses a laser beam when recording an image. In the exposure of the photothermographic material of the invention, it is desirable to use a light source appropriate for the color sensitivity imparted to the material. For example, if the material can be felt as infrared light, it can be applied to any light source in the infrared light range, but the laser power is high and the photothermographic material is made transparent. From the standpoint of being able to do so, an infrared semiconductor laser (780 nm, 820 nm) is more preferably used.

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 an angle between an exposure surface of a photosensitive material and a scanning laser beam does not become substantially perpendicular.

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

ビ ー ム The beam spot diameter on the photosensitive material exposed surface when the laser light is scanned on the photosensitive material is preferably 200 µm or less, more preferably 100 µm or less. It is preferable that the spot diameter is small in that the shift angle of the laser beam incident angle from the perpendicular can be reduced. Note that 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 occurrence of interference fringe-like unevenness.

As a second method, it is also preferable that the exposure in the present invention is performed using a laser scanning exposure machine that emits a scanning laser beam that is a vertical multi. Image quality deterioration such as generation of interference fringe-like unevenness is reduced as compared with the scanning laser beam in the longitudinal single mode.

To achieve vertical multiplication, a method such as combining, using return light, or superimposing a high frequency is 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.

Further, as a third aspect, it is preferable to form an image by scanning exposure using two or more laser beams.

Such an image recording method using a plurality of laser beams is used in an image writing means of a laser printer or a digital copier which writes an image by a plurality of lines in one scan due to a demand for higher resolution and higher speed. This technique is known, for example, from Japanese Patent Application Laid-Open No. 60-166916. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror to form an image on a photoreceptor via an fθ lens or the like. It is.

The image formation of the laser beam on the photoreceptor in the image writing means of the laser printer or the digital copier is performed by writing one image from a single laser beam for one line from the purpose of writing an image by a plurality of lines in one scan. The next laser light is imaged shifted. Specifically, the two light beams are close to each other at an interval of several tens of μm on the image plane in the sub-scanning direction, and the print density is 400 dpi (dpi is 1 inch, that is, the number of dots per 2.54 cm). ), The pitch in the sub-scanning direction of the two beams is 63.5 μm, and 42.3 μm at 600 dpi. Unlike such a method in which the resolution is shifted in the sub-scanning direction, in the present invention, it is preferable to form an image by focusing two or more lasers at the same location on the exposure surface while changing the incident angle. At this time, the exposure energy on the exposure surface when writing with one ordinary laser beam (wavelength λ [nm]) is E, and the N laser beams used for exposure have the same wavelength (wavelength λ [nm]). ), if the same exposure energy (E _n), preferably in the range of _{0.9 × E ≦ E n × n} ≦ 1.1 × E. By doing so, energy is secured on the exposed 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 generation of interference fringes is suppressed.

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

In the image recording methods of the first, second and third aspects described above, the laser used for scanning exposure is a solid laser such as a ruby laser, a YAG laser, or a glass laser, which is generally well known; Gas lasers such as Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He-Cd laser, N ₂ laser, excimer laser; 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 as appropriate according to the application. Among them, semiconductor lasers having a wavelength of 600 to 1200 nm are used due to maintenance and the size of the light source. It is preferable to use a laser beam according to In the laser light used in a laser imager or a laser imagesetter, the beam spot diameter on the exposed surface of the heat-developable material when scanning the material is generally 5 to 75 μm as a short axis diameter, and a long axis diameter. The laser beam scanning speed can be set to an optimum value for each photothermographic material by the sensitivity and laser power at the laser oscillation wavelength inherent to the photothermographic material.

The heat development processing apparatus according to the present invention includes a film supply unit represented by a film tray, a laser image recording unit, a heat development unit that supplies uniform and stable heat to the entire surface of the photothermographic material, and a film supply unit. And a transport section from the section through laser recording until the photothermographic material on which an image is formed by thermal development is discharged out of the apparatus. A specific example of the thermal development processing apparatus of this embodiment is shown in FIG.

The thermal developing apparatus 100 includes a feeding unit 110 that feeds a sheet-like photothermographic material (also referred to as a photothermographic element or simply a film) one by one, an exposure unit 120 that exposes the fed film F, and an exposure unit. A developing unit 130 for developing the film F, a cooling unit 150 for stopping the development, and a collecting unit 160, a pair of supply rollers 140 for supplying the film F from the feeding unit, and a film for feeding the film to the developing unit. And a plurality of roller pairs, such as transport roller pairs 141, 142, 143, and 145, for smoothly transporting the film F between the respective units. The heat developing section is a heating means for developing the film F. The heat drum 1 having a plurality of opposed rollers 2 which can be heated while being held almost in close contact with the outer periphery, and the peeling for peeling the developed film F and sending it to the cooling section. It consists of nails 6 and the like.

(4) The transport speed of the photothermographic material is preferably in the range of 10 to 200 mm / sec.

The development conditions of the photothermographic material of the present invention vary depending on the equipment, apparatus, or means used, but typically, by heating the photothermographic material imagewise exposed at a suitable high temperature. The development is performed. The latent image obtained after the exposure is heated at a moderately high temperature (about 80 to 200C, preferably about 100 to 200C, more preferably 110 to 140C) for a sufficient time (generally about 1 second to about 2 seconds). (Preferably 5 to 20 seconds) by heating the heat-developable material.

If the heating temperature is lower than 80 ° C, a sufficient image density cannot be obtained in a short time. If the heating temperature is higher than 200 ° C, the binder is melted, and not only the image itself such as transfer to a roller, but also the transportability and a developing machine. Also have an adverse effect. By heating, a silver image is generated by an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This reaction process proceeds without any supply of a processing liquid such as water from the outside.

機器 As a device, apparatus or means for heating, for example, a hot plate, an iron, a hot roller, a heating means typical of a heat generator using carbon or white titanium or the like may be used. More preferably, the heat-developable material provided with the protective layer may be subjected to heat treatment by bringing the surface having the protective layer into contact with a heating means, in order to perform uniform heating, and to improve heat efficiency and workability. From the viewpoint, it is preferable that the surface having the protective layer is conveyed while being brought into contact with the heat roller, subjected to heat treatment, and developed.

Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto.

Example 1
<< Preparation of Subtracted Photographic Support >>
A commercially available biaxially stretched heat-fixed PET film having a thickness of 175 μm and an optical density of 0.170 (measured with a densitometer PDA-65 manufactured by Konica Corp.) was colored 8 W / m ^2. For one minute, and apply the following undercoating coating solution a-1 on one surface so as to have a dry film thickness of 0.8 μm, and dry to form an undercoating layer A-1. The following undercoating coating solution b-1 was applied so as to have a dry film thickness of 0.8 μm and dried to obtain an undercoating layer B-1.

<< Undercoating liquid a-1 >>
Butyl acrylate (30% by mass)
t-butyl acrylate (20% by mass)
Styrene (25% by mass)
2-hydroxyethyl acrylate (25% by mass)
270 g of a copolymer latex solution (solid content: 30%)
(C-1) 0.6 g
Hexamethylene-1,6-bis (ethylene urea) 0.8 g
Finish to 1L with water << Coating solution b-1 >>
Butyl acrylate (40% by mass)
Styrene (20% by mass)
Glycidyl acrylate (40% by mass)
270 g of a copolymer latex solution (solid content: 30%)
(C-1) 0.6 g
Hexamethylene-1,6-bis (ethylene urea) 0.8 g
Finish to 1L with water.

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

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

<< Preparation of backcoat layer coating solution >>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (Eastman Chemical Co., CAB381-20) and 4.5 g of a polyester resin (Bostic, VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved solution, and 4.5 g of an F-based surfactant (Surflon KH40, Asahi Glass Co., Ltd.) dissolved in 43.2 g of methanol and an F-based surfactant (large 2.3 g of Nippon Ink Co., Ltd., Megafag F120K) was added and sufficiently stirred until dissolved. Next, 2.5 g of oleyl oleate was added. Finally, 75 g of silica (WR Grace, Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% by mass with a dissolver-type homogenizer was added and stirred to prepare a coating solution for the back coat layer.

<< Preparation of backcoat layer protective layer (surface protective layer) coating solution >>
Cellulose acetate butyrate (10% methyl ethyl ketone solution)
15g
Monodispersity 15% monodisperse silica (average particle size: 8 μm) 0.03
(Surface treatment with aluminum of 1% by mass of the total mass of silica)
C ₈ F ₁₇ (CH ₂ CH ₂ O) ₁₂ C ₈ F ₁₇ 0.05 g
Fluorosurfactant (SF-3) 0.01g
0.1 g of stearic acid
Oleyl oleate 0.1g
α-Alumina (Mohs hardness 9) 0.1g
<< Preparation of photosensitive silver halide emulsion A >>
(A1)
88.3 g of phenylcarbamoylated gelatin
Compound (A) (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water (B1)
0.67mol / L silver nitrate aqueous solution 2635ml
(C1)
Potassium bromide 51.55 g
1.47 g of potassium iodide
Finish to 660ml with water (D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
0.93 ml of iridium chloride (1% solution)
Finish to 1982ml with water (E1)
0.4 mol / L aqueous potassium bromide solution The following silver potential control amount (F1)
Potassium hydroxide 0.71g
Finish with water 20ml (G1)
56% acetic acid aqueous solution 18.0 ml
(H1)
1.72 g of anhydrous sodium carbonate
Make up to 151 ml with water Compound (A):
HO (CH ₂ CH ₂ O) _n (CH (CH ₃ ) CH ₂ O) ₁₇ (CH ₂ CH ₂ O) _m H
(M + n = 5-7)
Using a mixing stirrer disclosed in JP-B-58-58288 and JP-B-58-58289, a quarter of the solution (B1) and the total amount of the solution (C1) were controlled at a temperature of 20 ° C. and pAg of 8.09 in the solution (A1). While the mixture was added by the simultaneous mixing method in 4 minutes and 45 seconds, nucleation was performed. One minute later, the entire amount of the solution (F1) was added. During this time, pAg was appropriately adjusted using (E1). After a lapse of 6 minutes, ３ of the solution (B1) and the entire amount of the solution (D1) were added by a double jet method over 14 minutes and 15 seconds while controlling the temperature at 20 ° C. and the pAg at 8.09. After stirring for 5 minutes, the temperature was lowered to 40 ° C., and the whole amount of the solution (G1) was added to precipitate a silver halide emulsion. The supernatant was removed except for 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The supernatant was removed, leaving 1500 ml of the sedimented portion, and 10 L of water was further added. After stirring, the silver halide emulsion was sedimented. After removing the supernatant liquid leaving 1500 ml of the sedimented portion, 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 as to be 1161 g per 1 mol of silver, whereby photosensitive silver halide emulsion A was obtained.

乳 剤 This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 25 nm, a coefficient of variation in grain size of 12%, and a [100] face ratio of 92%.

<< Preparation of photosensitive silver halide emulsion B >>
The preparation was performed in the same manner as in the preparation of the photosensitive silver halide emulsion A, except that the temperature at the time of addition by the double jet method was changed to 40 ° C. This emulsion was monodisperse cubic silver iodobromide grains having an average grain size of 50 nm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

<< 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 aqueous sodium hydroxide solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the above sodium fatty acid solution at 55 ° C., 36.2 g of the above-mentioned photosensitive silver halide emulsion A, 9.1 g of the above-mentioned photosensitive silver halide emulsion B, and 450 ml of pure water were added. Stirred for minutes.

(4) Next, 468.4 ml of a 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 thereto, and the mixture was stirred and allowed to stand. Then, the organic silver salt dispersion was floated and separated to remove lower water-soluble salts. Thereafter, washing with deionized water and draining are repeated until the conductivity of the waste water becomes 2 μS / cm, and centrifugal dehydration is performed. The obtained organic silver salt in the form of a cake is then washed with an air-flow dryer flash jet dryer (stock). (Manufactured by Seishin Enterprise Co., Ltd.) and dried under a nitrogen gas atmosphere and operating conditions of hot air temperature at the dryer inlet until the water content becomes 0.1% to obtain dried powdered organic silver salt A.

赤 外線 An infrared moisture meter was used to measure the water content of the organic silver salt composition.

<< Preparation of Preliminary Dispersion A >>
An image forming layer binder, -SO ₃ K group containing polyvinyl butyral (Tg of 75 ° C., containing -SO ₃ K 0.2 mmol / g) 14.57 g was dissolved in methyl ethyl ketone 1457g to, VMA-GETZMANN Co. dissolver DISPERMAT CA- Preliminary dispersion liquid A was prepared by gradually adding 500 g of powdered organic silver salt A while stirring with a 40M mold and mixing well.

<< Preparation of photosensitive emulsion dispersion 1 >>
A media type disperser DISPERMAT SL- filled with 0.5% zirconia beads (Toray Toraycere) having a diameter of 0.5 mm so that the pre-dispersion liquid A has a residence time in the mill of 1.5 minutes using a pump. C1EX type (manufactured by VMA-GETZMANN) was supplied and dispersed at a mill peripheral speed of 8 m / s to prepare a photosensitive emulsion dispersion liquid 1.

<< Preparation of stabilizer solution >>
1.0 g of Stabilizer 1 and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare a stabilizer solution.

<< Preparation of infrared sensitizing dye solution A >>
19.2 mg of infrared sensitizing dye, 1.488 g of 2-chloro-benzoic acid, 2.779 g of Stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenzimidazole in 31.3 ml of MEK in the dark. And dissolved to prepare an infrared sensitizing dye solution A.

<< Preparation of additive liquid a >>
A reducing agent (compounds and amounts described in Tables 1 to 3) and a compound represented by the general formula (A-4) (compounds and amounts described in Tables 1 to 3); 1.54 g of 4-methylphthalic acid; .48 g of the infrared dye 1 was dissolved in 110 g of MEK to prepare an additive solution a.

<< Preparation of additive liquid b >>
1.56 g of the antifoggant 2, 3.43 g of phthalazine were dissolved in 40.9 g of MEK to prepare an additive liquid b.

<< Preparation of additive liquid c >>
As a silver saving agent, 0.5 g of the vinyl compound A1 represented by the general formula (G) was dissolved in 39.5 g of MEK to prepare an additive liquid c.

<< Preparation of additive liquid d >>
1 g of supersensitizer 1 was dissolved in 9 g of MEK to prepare an additive solution d.

<< Preparation of additive liquid e >>
1.0 g of the compound (types are described in Tables 1 to 3) was dissolved in 9.0 g of MEK to prepare an additive solution e. The numbers correspond to the numbers of the exemplified compounds described above.

<< Preparation of additive solution f >>
An antifoggant (compound (21)) containing 1.0 g of vinyl sulfone was dissolved in 9.0 g of MEK to prepare an additive solution f.

<< Preparation of additive liquid g >>
1.0 g of the compound represented by the general formula (A-10) (compound (19)) was dissolved in 9.0 g of MEK to prepare an additive liquid g.

<< Preparation of image forming layer coating solution >>
In an inert gas atmosphere (nitrogen 97%), the photosensitive emulsion dispersion liquid 1 (50 g) and MEK 15.11 g were kept at 21 ° C. while stirring, and the chemical sensitizer S-5 (0.5% methanol solution) was added. ) 1000 μl was added, and 2 minutes later, 390 μl of antifoggant 1 (10% methanol solution) was added, and the mixture was stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added, and the mixture was stirred for 10 minutes. Then, a gold sensitizer Au-5 corresponding to 1/20 mol of the organic chemical sensitizer was added, and the mixture was further stirred for 20 minutes. . Then, after adding 167 ml of stabilizer liquids and stirring for 10 minutes, 1.32 g of the said infrared sensitizing dye liquid A was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ° C., 6.4 g of the additive solution d, 0.5 g of the additive solution e, 0.5 g of the additive solution f, 8.0 g of the additive solution g, and the preliminary dispersion A After adding 13.31 g of the used binder and stirring for 30 minutes, 1.084 g of tetrachlorophthalic acid (9.4 mass% MEK solution) was added and stirred for 15 minutes. While further stirring, 12.43 g of Additive Solution a, 1.6 ml of Desmodur N3300 / Mobay's aliphatic isocyanate (10% MEK solution), 4.27 g of Additive Solution b, and 4.0 g of Additive Solution c The coating solution for the image forming layer was obtained by sequentially adding and stirring.

<< Preparation of image forming layer protective layer lower layer (surface protective layer lower layer) >>
5 g of acetone
21 g of methyl ethyl ketone
2.3 g of cellulose acetate butyrate
7 g of methanol
Phthalazine 0.25g
0.140 g of monodisperse silica having a monodispersity of 15% (average particle size: 3 μm)
(Surface treatment with aluminum of 1% by mass of the total mass of silica)
CH ₂ ＣＨCHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH ＝ CH ₂ 0.035 g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorosurfactant (SF-3) 0.01g
0.1 g of stearic acid
0.1 g of butyl stearate
α-Alumina (Mohs hardness 9) 0.1g
<< Preparation of upper layer of image forming layer protective layer (upper layer of surface protective layer) >>
5 g of acetone
21 g of methyl ethyl ketone
2.3 g of cellulose acetate butyrate
7 g of methanol
Phthalazine 0.25g
0.140 g of monodisperse silica having a monodispersity of 15% (average particle size: 3 μm)
(Surface treatment with aluminum of 1% by mass of the total mass of silica)
CH ₂ ＣＨCHSO ₂ CH ₂ CH ₂ OCH ₂ CH ₂ SO ₂ CH ＝ CH ₂ 0.035 g
C ₁₂ F ₂₅ (CH ₂ CH ₂ O) ₁₀ C ₁₂ F ₂₅ 0.01 g
Fluorosurfactant (SF-3) 0.01g
0.1 g of stearic acid
0.1 g of butyl stearate
α-Alumina (Mohs hardness 9) 0.1g
<< Preparation of photothermographic material >>
The backcoat layer coating solution and the backcoat layer protective layer coating solution prepared as described above are extruded onto the lower pull-up layer B-2 by a coater so that the dry film thickness becomes 3.5 μm, respectively, at a coating speed of 50 m / m. 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.

Simultaneous multilayer coating of the image forming layer coating solution and the image forming layer protective layer (surface protective layer) coating solution on the undercoating upper layer A-2 at an application speed of 50 m / min using an extrusion (extrusion) coater. The photosensitive material sample Nos. 1 to No. No. 15 was produced. In the coating, the image forming layer had a coated silver amount of 1.2 g / m ² , and the image forming layer protective layer (surface protective layer) had a dry film thickness of 2.5 μm (the surface protective layer upper layer 1.3 μm, the surface protective layer lower layer 1. 2 μm), and then dried for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

《Exposure and development processing》
The photothermographic material sample No. 1 produced as described above was used. 1 to No. After processing No. 15 into a half-cut size ((14 × 2.54) cm × (17 × 2.54) cm), it was processed in the following manner using the thermal development processing apparatus shown in FIG.

The photothermographic material is taken out of the film tray, transported to the laser exposure section, and then, from the image forming layer surface side, a vertical multi-mode semiconductor laser having a wavelength of 810 nm is superimposed on a high frequency (a maximum output of two 35 mW single lasers is combined). Exposure by laser scanning was given by an exposure machine using an exposure source of which the maximum output was 70 mW by wave. At this time, an image was formed at an angle of 75 degrees between the exposure surface of the photothermographic material and the exposure laser beam. Thereafter, the photothermographic material was conveyed to a photothermographic development unit, and was subjected to heat development at 125 ° C. for 15 seconds so that the heat drum was in contact with the protective layer on the image forming layer side of the photothermographic material and the drum surface. Thereafter, the photothermographic material was carried out of the apparatus. At this time, the conveying speed from the photosensitive material supply unit to the image exposing unit, the conveying speed in the image exposing unit, and the conveying speed in the heat developing unit were each set at 20 mm / sec. Exposure and development were performed in a room conditioned at 23 ° C. and 50% RH.

Image density The density of the image obtained under the above conditions is measured by a densitometer and is shown as an optical density.

Measurement of u ^* , v ^* and a ^* , b ^* in CIE 1976 color space Using a thermal developing apparatus shown in FIG. A wedge sample was prepared. The wedge density parts thus prepared were measured with CM-3600d (manufactured by Minolta Co., Ltd.) to calculate u ^* , v ^* or a ^* , b ^* . The measurement was performed in a transmission measurement mode with an F7 light source as a light source and a viewing angle of 10 °. The horizontal axis u ^* or a ^*, vertical axis v ^* or b ^* are plotted on the graph u ^*, v ^* or a ^*, b ^* were plotted obtains a linear regression line of determination R ^2, intercept, and The slope was determined. The graphs of u ^* and v ^* are shown in FIG. 2, and the results are shown in Tables 1 and 2. The graphs of a ^* and b ^* are shown in FIG. 3, and the results are shown in Table 3.

Image quality evaluation Thirty simple chest images were output to the samples prepared in the present invention and in the comparison. At that time, the lung field concentration was adjusted so that D = 1.7 ± 0.02. The evaluation was performed by a BRK method evaluation by seven persons using Shakasten having a luminance of 3200 cd / m ² . The evaluation score is an average value of 30 samples of each level, and the higher the score in both anatomical evaluation and physical evaluation, the better the image quality. The evaluation results are shown in Tables 1 to 3.

１〜３ From Tables 1 to 3, it is clear that the photothermographic material of the present invention has high scores in both anatomical evaluation and physical evaluation and is excellent in image quality as compared with the comparative photothermographic material.

FIG. 3 is a diagram illustrating a specific example of a thermal development processing apparatus. A linear regression line created by arranging u ^* and v ^* at each optical density on two-dimensional coordinates where the horizontal axis is u ^* and the vertical axis is v ^{* in the} CIE 1976 (L ^* u ^* v ^* ) color space. FIG. A linear regression line created by arranging a ^* and b ^* at each optical density on two-dimensional coordinates where the abscissa is a ^* and the ordinate is b ^{* in the} CIE 1976 (L ^* a ^* b ^* ) color space. FIG.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 heat drum 2 opposed roller 6 peeling claw 100 thermal development processing device 110 supply unit 120 exposure unit 130 thermal development unit 140 supply roller pair 141, 142, 143, 145 transport roller pair 144 supply roller pair 150 cooling unit 160 stacking unit F film C Film tray L Laser beam

Claims (20)

The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was the two-dimensional coordinates to v ^*, and wherein the u ^* at each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998 Photothermographic material. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was the v ^* to the two-dimensional coordinate in terms of the, u ^* of the above each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998, and a vertical axis A photothermographic material, wherein the value of v ^{* at} the intersection of is not less than -5 and not more than 5. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was Is determined by placing u ^* and v ^* at the above respective optical densities in two-dimensional coordinates where v ^* is v ^*, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and the slope (v ^* / U ^* ) is 0.7 or more and 2.5 or less. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was Is determined by arranging a ^* and b ^* at the respective optical densities in two-dimensional coordinates where b ^* is the b ^*, and the determination R ² of the linear regression line created is 0.998 or more and 1.000 or less. Photothermographic material. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was the two-dimensional coordinates to b ^*, a ^* in the above each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998, and a vertical axis A photothermographic material, wherein the b ^* value at the point of intersection is -5 or more and 5 or less. The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* and the vertical axis was the two-dimensional coordinates to b ^*, a ^* in the above each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998, and the slope (b ^* / A ^* ) is 0.7 or more and 2.5 or less. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . the two-dimensional coordinates, the photothermographic material characterized in that the u ^* at each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998 . The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . In the two-dimensional coordinates, u ^* and v ^* at the respective optical densities described above are arranged, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and v at the intersection with the vertical axis. ^{* A} photothermographic material having a value of -5 or more and 5 or less. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was u ^* , and the vertical axis was v ^* . the two-dimensional coordinates, u ^* of the above each optical density, v the linear regression line of determination R ² created arranged ^* is 1.000 or less than 0.998, and the slope (v ^* / u ^* Is 0.7 to 2.5. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . to the two-dimensional coordinates, the photothermographic material characterized in that the a ^* at each optical density, the linear regression line of determination R ² created by placing b ^* is 1.000 or less than 0.998 . The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . In the two-dimensional coordinates, a ^* and b ^* at each of the above optical densities are arranged, and the overlap determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and b at the intersection with the vertical axis ^{* A} photothermographic material having a value of -5 or more and 5 or less. The optical densities 0.5, 1.0, and 1.5 of the photothermographic material were measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was a ^* , and the vertical axis was b ^* . In the two-dimensional coordinates, a ^* and b ^* at each of the above optical densities are arranged, and the multiple determination R ² of the linear regression line created is 0.998 or more and 1.000 or less, and the slope (b ^* / a ^*) Is 0.7 to 2.5. The composition according to any one of claims 1 to 12, comprising a reducing agent represented by the following general formula (A-1) and a compound represented by the following general formula (A-4). Photothermographic material.

(In the formula, Z represents an atomic group necessary for constituting a 3- to 10-membered ring together with a carbon atom, and R _x represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group. R ₁ , R ₂ , Q ₀ represents a group substitutable on the benzene ring, L represents a divalent linking group, k is an integer of 0 to 1, n and m represents an integer of 0 to 2. plurality of R _1, R ₂ and Q ₀ may be the same or different.)

(Wherein, R ₄₁ represents a substituted or unsubstituted alkyl group, R ₄₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted acylamino group, and R ₄₁ and R ₄₂ represent 2- not be a hydroxyphenyl methyl group .R ₄₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group, R ₄₄ represents a substituent capable of substituting on the benzene ring.) 14. The photothermographic material according to claim 13, wherein at least one of R ₄₁ and R _{42 in} the general formula (A-4) is a secondary or tertiary alkyl group. 15. The photothermographic material according to claim 13, wherein the reducing agent represented by the general formula (A-1) is a reducing agent represented by the following general formula (A-2).

(Wherein, Q ₁ represents a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and Q ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, G represents a nitrogen atom or a carbon atom, and when G is a nitrogen atom, ng is 0. When G is a carbon atom, ng is 0 or 1. Z ₂ is carbon atom. And a group of atoms necessary to form a 3- to 10-membered non-aromatic ring together with the atom and G. R ₁ , R ₂ , R _x , Q ₀ , L, k, n, and m are represented by the general formula ( It is the same as that in A-1). The photothermographic material according to any one of claims 13 to 15, wherein the non-aromatic ring represented by Z ₂ in the general formula (A-2) is a 6-membered. The layer on the side having the image forming layer of the photothermographic material contains at least one silver saving agent selected from a vinyl compound, a hydrazine derivative, a silane compound and a quaternary onium salt. 17. The photothermographic material according to any one of items 1 to 16. An image forming method, comprising developing the photothermographic material according to any one of claims 1 to 17 at a temperature of 110 ° C to 140 ° C for a time of 5 seconds to 20 seconds to form an image. . An image forming method, comprising exposing the photothermographic material according to any one of claims 1 to 17 with a laser wavelength of 400 nm to 830 nm to form an image. An image forming method, comprising exposing the photothermographic material according to any one of claims 1 to 17 with a laser wavelength of 780 nm to 830 nm to form an image.

Images