JP2004191939A - Silver salt photothermographic dry imaging material, image recording method using the same, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material having high sensitivity and low fog, excellent in image color tone and in silver image stability after heat development, and excellent also in image density unevenness, and to provide an image recording method using the same and an image forming method for the same. <P>SOLUTION: The silver salt photothermographic dry imaging material containing a photosensitive emulsion comprising non-photosensitive silver aliphatic-carboxylate grains and photosensitive silver halide grains, a silver ion reducing agent and a binder, is characterized in that a cyan-developing leuco dye is contained and the photosensitive silver halide grains include photosensitive silver halide grains having an average grain diameter of 0.01-0.04 μm in a ratio of 5-50 mass% of all the photosensitive silver halide grains (expressed in terms of silver). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a silver salt photothermographic dry imaging material, and an image recording method and an image forming method using the same.

  In recent years, in the field of medical treatment and printing plate making, the waste liquid due to wet processing of image forming materials has become a problem in terms of workability, and it is strongly desired to reduce the processing waste liquid from the viewpoint of environmental conservation and space saving. I have. Therefore, there is a need for a technique relating to a photothermographic material for photographic technology, such as a laser imager or a laser imagesetter, capable of efficient exposure and capable of forming a high-resolution, clear black image. ing.

  Examples of the technique relating to the photothermographic material include, for example, U.S. Pat. Nos. 3,152,904 and 3,487,075 or D.C. H. "Dry Silver Photographic Materials" by Klosterboer (Handbook of Imaging Materials, Marcel Dekker, Inc., p. 48, 1991), and the like, as described in Organics, p. 48, 1991. A silver salt photothermographic dry imaging material containing a silver salt, a photosensitive silver halide and a reducing agent is known. Since this silver salt photothermographic dry imaging material does not use any solution-based processing chemicals, it has an advantage that a user can be provided with a system that is simpler and does not damage the environment.

  These silver salt photothermographic dry imaging materials use a photosensitive silver halide particle provided in a photosensitive layer as a light sensor, an organic silver salt as a supply source of silver ions, and 80 to 250 depending on a built-in reducing agent. It is characterized in that an image is formed by heat development at a temperature of ° C. and no fixing is performed.

  In a dry imaging material as well as a conventional photosensitive material, it is desirable to minimize the amount of silver which is a precious resource. A basic technique is to reduce the size of photosensitive silver halide grains. In other words, when the number of development start points is increased, the individual developed silver generated after heat development becomes minute, so that in a dry imaging material prepared with the same silver amount, the cross-sectional area occupied by the developed silver per unit cross-sectional area of the material. Is increased, which is advantageous in optical density. That is, the covering power value is improved, the maximum density can be increased, or silver saving can be achieved. Other examples of the technology for increasing the covering power include, for example, a compound capable of imagewise generating a chemical species capable of forming a development start point on and near a non-photosensitive aliphatic carboxylic acid silver salt. And a technique of including a compound similar to the above in a dry imaging material is disclosed (for example, see Patent Documents 1 and 2). These techniques have been shown to improve the covering power, but have drawbacks. Degradation of the image tone is one example. That is, as described in The theory of the Photographic Process Fourth Edition, pages 475 to 476, and Journal of Chemical Physics, p-6755-p-6759 116 (2002), the size and shape of the developed silver changes when the absorption changes, as described in p. The color tone of the developed silver changes depending on the light scattering characteristics. When the finely developed silver is generated, it becomes mainly reddish, so that the color tone often deviates from the market. This change in color tone is considered to be due to an increase in the number and ratio of minute silver clusters, and is particularly noticeable in a high density region where the optical density is 2.0 or more. Thus, it has been difficult to achieve both high covering power and preferable control of image tone. In particular, in silver salt photothermographic dry imaging materials for medical applications, it is said that improving the image quality to enable more accurate diagnosis is one of the very important characteristics, one example of which is that the eyes are less tiring during observation. Image tones having various color tones are desired.

  On the other hand, efforts have been made to improve the color tone. For example, in order to control the shape and size of the developed silver, a mix of photosensitive silver halides having different grain sizes and a change in halide composition have been studied. In addition, although a device using a compound called a toning agent known to play a role of a silver carrier at the time of heat development is disclosed (for example, see Patent Documents 3 and 4), it is said that a sufficient improvement has been obtained. Is hard to say.

  Attempts have also been made to improve color materials. For example, although an improvement by a leuco dye is disclosed (for example, see Patent Documents 5 and 6), only a part of the hue can be controlled, and further, there is no description in the color tone improvement at an optical density of 2.0 or more. If not, there is no suggestion. Although improvements using coupler-type coloring dyes are also disclosed (see, for example, Patent Document 7), color tone control is difficult, and a slight shift in color tone occurs in each processing, resulting in poor reproducibility.

  Further, when a large number of fine silver clusters are present, so-called image storability tends to deteriorate, such as when the imaging material after the heat treatment is exposed to irradiation light. Specifically, there are many examples in which the silver image density and the color tone are apt to change. If the sensitivity of the photosensitive silver halide remaining after the heat treatment is low, this effect can be reduced, but it cannot be said that it is still at a sufficient level, and the sensitivity at the time of ordinary exposure is undesirably reduced. Although the reason other than the above-mentioned photosensitivity is not clear, for example, the smaller the silver cluster, the more the number increases, and this may be likely to serve as a catalyst for reducing the silver of the remaining silver salt, or a small This may be because the developed silver itself is unstable to light and heat.

Therefore, there is a strong demand for a technique for improving the color tone of an image while achieving high covering power and improving the image storability after a heat treatment.
JP-A-2002-287294 (page 1) JP-A-2002-296730 (page 1) JP 2002-116522 A (page 1) JP 2002-174877 A (page 1) JP-A-11-231460 (page 1) JP 2002-169249 A (page 1) JP 2001-264927 A (page 1)

  The present invention has been made in view of the above-mentioned problems, and a first object of the present invention is to provide a silver salt photothermographic dry film having high sensitivity, low fog, and excellent image tone and silver image stability after heat development. An object of the present invention is to provide an imaging material and an image recording method and an image forming method using the same. A second object of the present invention is to provide a silver salt photothermographic dry imaging material capable of reproducing substantially the same image tone even when the density region changes, and an image recording method and an image forming method using the same. . Further, a third object of the present invention is to provide a silver salt photothermographic dry imaging material which is excellent in reproducibility of image color tone for each heat treatment and has improved density unevenness after the heat treatment, an image recording method using the same, and An object of the present invention is to provide an image forming method.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material The photosensitive silver halide particles containing a cyan-chromogenic leuco dye, wherein the ratio of the photosensitive silver halide particles having an average particle diameter of 0.01 μm or more and 0.04 μm or less is the total photosensitive halogen in terms of silver amount. A silver salt photothermographic dry imaging material, characterized in that the content is 5% by mass or more and 50% by mass or less of silver halide particles.
(Claim 2)
Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material A silver ion-containing solution containing a cyan coloring leuco dye, wherein the non-photosensitive aliphatic carboxylic acid silver salt particles are water or a mixture of water and an organic solvent as a solvent in the presence of a tertiary alcohol; A silver salt photothermographic dry imaging material produced by reacting a solution containing an alkali metal salt of an aliphatic carboxylic acid with an organic solvent or a mixture of water and an organic solvent as a solvent.
(Claim 3)
The non-photosensitive silver aliphatic carboxylate particles are, in the presence of a tertiary alcohol, a solution containing silver ion containing water or a mixture of water and an organic solvent, and water, an organic solvent, or water and an organic solvent. The silver salt photothermographic dry imaging material according to claim 1, wherein the silver salt photothermographic dry imaging material is produced by reacting a solution containing an alkali metal salt of an aliphatic carboxylic acid with a mixture of the solvent and a solvent.
(Claim 4)
Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material A silver salt photothermographic dry imaging material containing a cyan-coloring leuco dye and a binder containing a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH.
(Claim 5)
The silver salt photothermographic dry imaging material according to any one of claims 1 to 3, wherein the binder contains a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C and 60% RH.
(Claim 6)
Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material each containing a binder, wherein the photothermographic imaging material is Each of the optical densities 0.5, 1.0, 1.5 and the minimum optical density of the silver image obtained after the heat development was measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was expressed as u. ^* and the vertical axis the two-dimensional coordinates to v ^*, the u ^* at each optical density, v ^* was placed create determine coefficients of a linear regression line was (multiple determination) R ² is 0.998 or more, 1. 000 or less, and the v ^* value at the intersection with the vertical axis of the linear regression line is -5 or more and 5 or less, and the slope (v ^* / u ^* ) is 0.7 or more and 2.5 or less. The silver salt photothermography according to any one of claims 1 to 5, Lai imaging material.
(Claim 7)
The image recording method for recording an image on a silver salt photothermographic dry imaging material according to any one of claims 1 to 6, wherein the exposure is performed by a laser beam scanning exposure device in which a scanning laser beam is a vertical multi. Image recording method.
(Claim 8)
An image forming method, wherein the silver salt photothermographic dry imaging material according to any one of claims 1 to 6 is thermally developed in a state where the material contains an organic solvent in an amount of 40 to 4500 ppm.

  According to the present invention, a silver salt photothermographic dry imaging material having excellent storage stability, excellent image stability after thermal development, and excellent thermal development stability, while having high sensitivity and low fog, and Image recording method and image forming method can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  One of the features of the silver salt photothermographic dry imaging material of the present invention (hereinafter, also simply referred to as a light-sensitive material) is to use a cyan coloring leuco dye as a color tone adjuster.

(Cyan coloring leuco dye)
The leuco dye is preferably any colorless or slightly colored compound that oxidizes to a colored form when heated at a temperature of about 80-200 ° C. for about 0.5-30 seconds, and is oxidized by silver ions to form a dye. Any of the leuco dyes which form the above can be used in the present invention. Compounds that are pH sensitive and can be oxidized to a colored state are useful. Representative leuco dyes include, for example, biphenol leuco dyes, phenol leuco dyes, indoliniline leuco dyes, acrylated azine leuco dyes, phenoxazine leuco dyes, phenodiazine leuco dyes, and phenothiazine leuco dyes. Also useful are U.S. Pat. Nos. 3,445,234, 3,846,136, 3,994,732, 4,021,249, and 4,021, No. 250, No. 4,022,617, No. 4,123,282, No. 4,368,247, No. 4,461,681 and JP-A-50-36110 described above. This is a leuco dye disclosed in Japanese Unexamined Patent Publication Nos. 59-206831, 5-204087, 11-231460, 2002-169249, and 2002-236334.

  In the present invention, a color image forming agent which is preferably used as a cyan-color-forming leuco dye, whose absorbance at 600 to 700 nm is increased by being oxidized, is disclosed in JP-A-59-206831 (particularly when λmax is 600 to 700 nm). Compounds within the range of 700 nm), and compounds of the general formulas (I) to (IV) of JP-A-5-204087 (specifically, (1) to (0037) described in paragraphs “0032” to “0037”). 18) and the compounds of the general formulas 4 to 7 in JP-A-11-231460 (specifically, the compounds of Nos. 1 to 79 described in paragraph “0105”).

  The cyan coloring leuco dye particularly preferably used in the invention is represented by the following general formula (CL).

In the formula, R ₈₁ and R ₈₂ represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an alkoxy group, a —NHCO—R ₁₀ group (R ₁₀ is an alkyl group, an aryl group, a heterocyclic group, ) Or R ₈₁ and R ₈₂ are a group linked together to form an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring or a heterocyclic ring. A ₈ represents a —NHCO— group, —CONH— group or —NHCONH— group, and R ₈₃ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. Further, -A ₈ -R ₈₃ may be a hydrogen atom. W ₈ is a hydrogen atom, a —CONH—R ₈₅ group, a —CO—R ₈₅ group, or a —CO—O—R ₈₅ group (R ₈₅ represents a substituted or unsubstituted alkyl group, an aryl group, or a heterocyclic group) And R ₈₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, carbamoyl group, or nitrile group. R ₈₆ represents a —CONH—R ₈₇ group, a —CO—R ₈₇ group, or a —CO—O—R ₈₇ group (R ₈₇ represents a substituted or unsubstituted alkyl group, aryl group, or heterocyclic group). . X ₈ represents a substituted or unsubstituted aryl group or heterocyclic group.

In the general formula (CL), examples of the halogen atom represented by R ₈₁ and R ₈₂ include a fluorine atom, a bromine atom, a chlorine atom and the like. As the alkyl group, an alkyl group having up to 20 carbon atoms (eg, Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (eg, vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-ethyl). A propenyl group, a 3-butenyl group, a 1-methyl-3-propenyl group, a 3-pentenyl group, a 1-methyl-3-butenyl group, and the like. As the alkoxy group, an alkoxy group having up to 20 carbon atoms (eg, methoxy group) Group, ethoxy, etc.). Examples of the alkyl group represented by R ₁₀ in the —NHCO—R ₁₀ group include an alkyl group having up to 20 carbon atoms (eg, a methyl group, an ethyl group, a butyl group, a dodecyl group, etc.), and an aryl group Examples thereof include groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group. . The alkyl group represented by R ₈₃ is preferably an alkyl group having up to 20 carbon atoms, for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, etc., and an aryl group preferably has 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group. -CONH-R ₈₅ groups represented by W _8, in -CO-R ₈₅ group, or -CO-O-R ₈₅ group, the alkyl group represented by R ₈₅ is preferably an alkyl group having up to 20 carbon atoms And examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group. The aryl group is preferably an aryl group having up to 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

Examples of the halogen atom represented by R ₈₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include a chain or cyclic alkyl group such as a methyl group, a butyl group, and a dodecyl group. Group, cyclohexyl group and the like. Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (e.g., vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl and the like, and the alkoxy group includes, for example, a methoxy group, a butoxy group and a tetradecyloxy group, and carbamoyl Examples of the group include a diethylcarbamoyl group and a phenylcarbamoyl group. Nitrile groups are also preferred. Among these, a hydrogen atom and an alkyl group are more preferred. R ₈₃ and R ₈₄ may be linked to each other to form a ring structure.
The above groups can further have a single substituent or multiple substituents. Typical substituents include a halogen atom (eg, fluorine, chlorine, bromine, etc.), an alkyl group (eg, methyl, ethyl, propyl, butyl, dodecyl, etc.), a hydroxyl group, a cyano group , Nitro group, alkoxy group (eg, methoxy group, ethoxy group, etc.), alkylsulfonamide group (eg, methylsulfonamide group, octylsulfonamide group, etc.), arylsulfonamide group (eg, phenylsulfonamide group, naphthylsulfone) Amide group), alkylsulfamoyl group (eg, butylsulfamoyl group), arylsulfamoyl (eg, phenylsulfamoyl group), alkyloxycarbonyl group (eg, methoxycarbonyl group), aryl Oxycarbonyl group (for example, phenyloxycarbonyl group, etc. , Amino sulfonamido group, an acylamino group, a carbamoyl group, a sulfonyl group, a sulfinyl group, a sulfoxy group, a sulfo group, an aryloxy group, an alkoxy group, an alkylcarbonyl group, arylcarbonyl group, and an amino carbonyl group.

R ₁₀ or R ₈₅ is preferably a phenyl group, and more preferably a phenyl group having a plurality of halogen atoms and cyano groups as substituents.

-CONH-R ₈₇ group represented by R _86, in -CO-R ₈₇ group, or -CO-O-R ₈₇ group, the alkyl group represented by R ₈₇ is preferably an alkyl group having up to 20 carbon atoms There are, for example, a methyl group, an ethyl group, a butyl group, a dodecyl group and the like, and the aryl group is preferably an aryl group having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

As the substituent which the group represented by R ₈₇ can have, the same substituents as those described in the description of R _{81 to} R _{84 in} formula (CL) can be used.

The aryl group represented by X _8, a phenyl group, a naphthyl group, an aryl group having 6 to 20 carbon atoms such as thienyl group. Examples of the heterocyclic group include thiophene group, a furan group, imidazole Group, pyrazole group, pyrrole group and the like.

Examples of the substituent which the group represented by X ₈ can have include the same substituents as those described in the description of R _{81 to} R _{84 in} formula (CL).

As the group represented by X ₈ , an aryl group or a heterocyclic group having an alkylamino group (such as a diethylamino group) at the para position is preferable. These groups may include photographically useful groups.

It is preferable to use leuco dyes of various colors alone or in combination of a plurality of types in order to adjust to a predetermined color tone. In particular, the dye used in the present invention is a leuco dye that develops cyan, and if it develops the same cyan, leuco dyes having different structures can be used alone or in combination. The color density is preferably adjusted appropriately in relation to the color tone of the developed silver itself. In the present invention, the color is formed so as to have a reflection optical density of 0.01 to 0.05 or a transmission optical density of 0.005 to 0.03, and the color tone is adjusted so as to obtain an image having a preferable color tone range shown below. Is preferred. As a method of addition, these compounds can be dispersed in water or dissolved in an organic solvent to be contained in a coating solution for a photosensitive layer or a coating solution for an adjacent layer thereof, so as to be contained in these layers. As the organic solvent, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aromatic solvents such as toluene and xylene can be arbitrarily selected. The amount used is suitably in the range of 1 × 10 ⁻² to 10 mol, preferably 1 × 10 ^{−2 to} 1.5 mol, per mol of silver. Further, the molar ratio of the cyan coloring leuco dye to the total amount of the reducing agents represented by the following general formulas (A-1) to (A-5) is 0.001 to 0.2. Is preferably, and more preferably 0.005 to 0.1. In particular, specific examples of the leuco dye which develops cyan color which are preferable for the present invention are described in the above-mentioned JP-A-5-204087 and JP-A-11-231460. The structural formulas are listed below, but are not limited thereto.

  In addition, it is preferable to use a leuco-type yellow coloring dye in combination as necessary. A preferred dye structure is represented by the following general formula (1).

In Formula (1), Z -S- group or _{-C (R 33) (R 33} ') - represents a group, R _33, R _33' each represents a hydrogen atom or a substituent. Examples of the substituent represented by R ₃₃ or R ₃₃ ′ include, for example, an alkyl group, (methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, sec-butyl, t-butyl, t-amyl, t-octyl, Groups such as cyclohexyl and 1-methyl-cyclohexyl), alkenyl groups (such as vinyl, propenyl, butenyl, pentenyl, isohexenyl, cyclohexenyl, butenylidene, and isopentylidene), and alkynyl groups (such as ethynyl and propynylidene). Group), an aryl group (each group such as phenyl and naphthyl), a heterocyclic group (each group such as furyl, thienyl, pyridyl, and tetrahydrofuranyl), halogen, hydroxyl, alkoxy, aryloxy, acyloxy, sulfonyloxy, Nitro, amino, acylamino, sulfoni Amino, sulfonyl, carboxy, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, cyano, each group sulfo and the like. R ₃₃ and R ₃₃ ′ are preferably a hydrogen atom or an alkyl group.

R ₃₁ , R ₃₂ , R ₃₁ ′, and R ₃₂ ′ each represent a substituent, and examples of the substituent include the same groups as those described for R ₃₃ and R ₃₃ ′ in the general formula (1). Is mentioned.

R ₃₁ , R ₃₂ , R ₃₁ ′, and R ₃₂ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, etc., and more preferably an alkyl group.

Examples of the substituent on the alkyl group include the same groups as those described above for R ₃₃ and R ₃₃ ′.

R ₃₁ , R ₃₂ , R ₃₁ ′ and R ₃₂ ′ are more preferably tertiary alkyl groups such as t-butyl, t-amyl, t-octyl and 1-methyl-cyclohexyl.

X ₃₁ and X ₃₁ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as those described above for R ₃₃ and R ₃₃ ′.

  Hereinafter, specific examples of the bisphenol compound represented by the general formula (1) are shown, but the present invention is not limited thereto.

  The preferred form and amount of addition are the same as the preferred ranges of the cyan-color-forming leuco dye described above.

(Photosensitive silver halide grains)
Next, photosensitive silver halide grains (hereinafter, also simply referred to as silver halide grains) used in the silver salt photothermographic dry imaging material of the present invention will be described. Incidentally, the photosensitive silver halide grains in the present invention can inherently absorb light as an inherent property of silver halide crystals, or artificially emit visible light or infrared light by a physicochemical method. When it can be absorbed, and absorbs light in any region within the light wavelength range from the ultraviolet light region to the infrared light region, a physicochemical change may occur in the silver halide crystal or on the crystal surface. As described above.

  The silver halide grains used in the present invention are themselves P.I. Chimie et Physique Photographique (Paul Montel, 1967) by Glafkides; F. Duffin, Photographic Emulsion Chemistry (published by The Focal Press, 1966); L. It can be prepared as a silver halide grain emulsion using a method described in Making and Coating Photographic Emulsion by Zelikman et al (published by 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 and a soluble halide may be any one of a one-side mixing method, a simultaneous mixing method, a combination thereof and the like. Of these methods, the so-called controlled double jet method 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. Particularly preferred is silver halide.

  In the case of silver iodobromide, the iodine content is preferably in the range of 0.02 to 6 mol% / Ag mol. The iodine may be contained so as to be distributed throughout the silver halide grains, or the iodine concentration may be increased at a specific portion of the silver halide grains, for example, at the center of the grains, and the density near the surface may be lowered or substantially reduced. A core / shell type structure that is zero above may be used.

  Grain formation is usually divided into two stages of silver halide seed grain (nucleus grain) generation and grain growth, and these methods may be performed continuously at once, or the nucleus (seed grain) formation and grain growth may be separated. It is also possible to use a method of performing this. As a particle forming condition, a controlled double jet method in which particles are formed by controlling pAg, pH and the like is preferable in that the shape and size of the particles can be controlled. For example, in the case of a method in which nucleation and grain growth are performed separately, first, a nucleation (nucleation step) is performed by uniformly and rapidly mixing a soluble silver salt and a soluble halide in an aqueous gelatin solution. The silver halide grains are prepared by a grain growth step of growing grains while supplying a soluble silver salt and a soluble halide under controlled pAg, pH, and the like.

  The silver halide grains used in the present invention preferably have a smaller particle size as a whole in order to suppress white turbidity and color tone (yellow tint) after image formation and to obtain good image quality. In the present invention, the total (in terms of silver amount) of silver halide grains having a particle size in the range of 0.01 μm to 0.04 μm is in the range of 5 to 50% by mass of the silver content of all silver halide grains. One feature is that the silver amount of the silver halide grains in the range of 0.02 μm to 0.04 μm is preferably set as a value when particles having an average particle diameter of less than 0.02 μm are excluded from the measurement. Is 10 to 40% by mass or less of the silver content of all silver halide grains.

  By setting the silver halide grain distribution to be used in the range specified above, both the covering power and the image color tone are compatible. That is, when the ratio of silver halide having a small grain size is high, the number of development points is increased and a high covering power is obtained. On the other hand, the color tone of the image, particularly in the high density region, of the heat development is reddish and tends to deteriorate, possibly due to an increase in the number of minute developed silver, but it is improved by using the cyan-forming leuco dye in combination. Furthermore, when fine developed silver or fine silver halide particles are present, the optical density and the image color tone during image storage are liable to change, but the particle size and the mass ratio within the range of the present invention show significant deterioration. It is reduced to the extent that it does not become.

  When the silver halide grains are so-called cubic or octahedral so-called normal crystals, the grain size refers to the length of the edge of the silver halide grains. In the case where the silver halide grains are tabular grains, the diameter means a diameter when converted into a circular image having the same area as the projected area of the main surface.

  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 diameter 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 the silver halide grains include cubes, octahedrons, tetradecahedral grains, tabular grains, spherical grains, rod-shaped grains, potato-like grains, among which, among others, cubic, octahedral, Tetradecahedral, tabular silver halide grains are preferred.

  When tabular silver halide grains are used, the average aspect ratio 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. Patent Nos. 5,264,337, 5,314,798, and 5,320,958, and can easily obtain target tabular grains. Further, grains having rounded corners of silver halide grains can also be preferably used.

  There is no particular limitation on the crystal habit on the outer surface of the silver halide grains, but when a spectral sensitizing dye having crystal habit (plane) selectivity is used 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, in the case of using a sensitizing dye which selectively adsorbs to a crystal plane having a Miller index of [100], it is preferable that the proportion occupied by the [100] plane on the outer surface of the silver halide grains is high, and this proportion is 50%. %, More preferably 70% or more, particularly preferably 80% or more. Incidentally, the ratio of the Miller index [100] plane is determined by the T.T. 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 grain formation, and particularly preferably at the time of nucleation of silver halide grains. The low molecular weight gelatin has an average molecular weight of 50,000 or less, preferably 2000 to 40000, and more preferably 5000 to 25,000. The average molecular weight of gelatin can be measured by gel filtration chromatography.

  As the silver halide grains used in the present invention, a polyethylene oxide compound represented by the following general formula can be used at the time of grain formation.

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 chain 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 for producing a 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, It has been preferably used as an antifoaming agent against remarkable foaming in the case of stirring or moving the emulsion raw material such as a step of coating on the surface. No. 9497, and the polyethylene oxide compound represented by the above general formula also functions as an antifoaming agent at the time of nucleation.

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

  The polyethylene oxide compound represented by the above general formula may be present at the time of nucleation, and is preferably added in advance to the dispersion medium before nucleation, but may be added during nucleation, It may be used by adding to a silver salt aqueous solution or a halide aqueous solution used at the time of nucleation. Preferably, it is added to the aqueous halide solution or both aqueous solutions at 0.01 to 2.0% by mass. Also, it is preferably present for at least 50% of the time of the nucleation step, more preferably for at least 70% of the time. The polyethylene oxide 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 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 pattern at the end of nucleation is 40 ° C.) or the reverse pattern.

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 silver ion addition during nucleation is preferably 1.5 × 10 ^{−3 to} 3.0 × 10 ⁻¹ mol / min, more preferably 3.0 × 10 ^{−3 to} 8.0 per liter of the reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can be set in the range of 1.7 to 10, but the pH on the alkali side is preferably pH 2 to 6 in order to broaden the particle size distribution of nuclei to be formed. In addition, pBr at the time of nucleation is about 0.05 to 3.0, preferably 1.0 to 2.5, and more preferably 1.5 to 2.0.

  The photosensitive silver halide grains according to the present invention form a latent image capable of functioning as a catalyst for a development reaction on the surface of the silver halide grains during exposure before thermal development, and form the latent image during exposure after thermal development. One feature is that the silver halide grains suppress formation of a latent image on the surface because many latent images are formed inside the surface of the silver halide grains.

  Further, as described in Example-11 of US Pat. No. 6,423,481, photosensitive silver halide grains formed in an organic solvent may be used. That is, if the protective colloid of AgX and the dispersion binder of the silver aliphatic carboxylate are the same, the photosensitive silver halide grains and the non-photosensitive aliphatic silver carboxylate grains become uniform and easily adjacent to each other. When the silver released from the non-photosensitive aliphatic silver carboxylate particles during heat development easily moves to and near the latent image on the photosensitive silver halide serving as a catalyst, so that a higher covering power is obtained. Because there is.

  In the present invention, it is preferable that the electron trapping dopant is contained in the inside of the silver halide grains. With this constitution, the sensitivity and the image storability are improved.

  In the present invention, the method for incorporating an appropriate dopant into the photosensitive silver halide grains is not particularly limited, and for example, the method described in JP-A-9-43765 and JP-A-2001-42471 can be used. Can be used. The electron trapping dopant used herein is an element or a compound other than silver and halogen constituting silver halide, and the dopant itself has a property of trapping (trapping) free electrons or the dopant is halogenated. It means that a site such as an electron trapping lattice defect is generated by being contained in silver particles. For example, a metal ion other than silver or a salt or complex thereof, a chalcogen (oxygen group element) such as sulfur, selenium, or tellurium, or a chalcogen, or an inorganic or organic compound containing a nitrogen atom, a rare earth ion or a complex thereof, and the like can be given. .

  Examples of the metal ion or its salt or complex include lead ion, bismuth ion, gold ion, or lead bromide, lead nitrate, lead carbonate, lead sulfate, bismuth nitrate, bismuth chloride, bismuth trichloride, bismuth carbonate, sodium bismuthate, Examples thereof include chloroauric acid, lead acetate, lead stearate, and bismuth acetate.

  As the compound containing a chalcogen such as sulfur, selenium, tellurium, various compounds having a chalcogen releasing property generally known as a chalcogen sensitizer in the photographic industry can be used. As the organic substance containing chalcogen or nitrogen, a heterocyclic compound is preferable. For example, 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, benzthiazole, indolenine, tetrazaindene, preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole, oxadiazole, quinoline, phthalazine, Naphthyridine, quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, Sasol, benzimidazole, benzoxazole, benzthiazole, a tetrazaindene.

  Note that the above heterocyclic compound may have a substituent, and as the substituent, preferably, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an acyl group, or an alkoxycarbonyl group An aryloxycarbonyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, a sulfonyl group, a ureido group, a phosphoric amide group, a halogen atom, a cyano group, A sulfo group, a carboxyl group, a nitro group, and a heterocyclic group, more preferably an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, and a sulfonyl. A mino group, a sulfamoyl group, a carbamoyl group, a ureido group, a phosphoric acid amide group, a halogen atom, a cyano group, a nitro group, a heterocyclic group, and more preferably an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or 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.

  In the silver halide grains used in the present invention, groups 6 to 11 of the Periodic Table of the Elements are provided so as to function as electron trapping dopants like the above-mentioned dopants or to function as hole trapping dopants. May be contained by chemically preparing the oxidation state of the metal with a ligand (ligand) or the like. As the above transition metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, and Pt are preferable.

  In the present invention, the above-mentioned various dopants may be used alone or in combination of two or more of the same or different compounds or complexes. These dopants may be incorporated into the silver halide grains in any chemical form.

The content of the dopant is preferably in the range of 1 × 10 ⁻⁹ to 1 × 10 mol, more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol, per mol of silver. Further, the amount is preferably 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol.

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

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

General formula [ML ₆ ] ^m
In the formula, M represents a transition metal selected from elements of Groups 6 to 11 of the periodic table, L represents a ligand, and m represents 0,-, 2-, 3- or 4-. Specific examples of the ligand represented by L include halogen ions (for example, fluorine ions, chlorine ions, bromine ions, iodine ions), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Examples include each ligand, nitrosyl, thionitrosyl and the like, and preferred are 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 the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening , May be added at any stage before and after the chemical sensitization, in particular, nucleation, growth, preferably added at the stage of physical ripening, more preferably nucleation, added at the stage of growth, Most preferably, it is added at the stage of nucleation. In the addition, it may be added in several divided portions, and may be uniformly contained in the silver halide grains. For example, JP-A-63-29603, JP-A-2-306236, As described in JP-A-3-167545, JP-A-4-76534, JP-A-6-110146, JP-A-5-273683 and the like, the particles can be contained in the particles with a distribution.

  These metal compounds can be added by dissolving them 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 solution and a halide 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 a metal ion or a complex ion 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 a water-soluble 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 during physical ripening, or at the time of chemical ripening.

  Incidentally, the non-metallic dopant can be introduced into the silver halide by the same method as the above-mentioned metallic dopant. In the imaging material according to the present invention, whether or not the above dopant has an electron trapping property can be evaluated by a method generally used conventionally in the photographic industry as follows. That is, a silver halide emulsion composed of silver halide grains in which the above-mentioned dopant or a decomposition product thereof is doped in silver halide grains is subjected to halogenation without dopant by photoconductivity measurement using a microwave photoconductivity measurement method or the like. The evaluation can be made by measuring the degree of decrease in photoconductivity based on the silver particle emulsion. Alternatively, it can be carried out by a comparison experiment between the internal sensitivity and the surface sensitivity of the silver halide grains.

  The silver halide grains according to the present invention may be added to the light-sensitive layer by any method. In this case, the silver halide grains are arranged so as to be close to a reducible silver source (silver aliphatic carboxylate). Is preferred.

(Silver aliphatic carboxylate particles)
The silver halide according to the present invention is prepared in advance, and this can be added to a solution for preparing aliphatic carboxylic acid silver salt grains. Can be treated separately, which is preferable also in production control. However, as described in British Patent No. 1,447,454, when preparing aliphatic carboxylic acid silver salt particles, a halogen component such as a halide ion is used. Silver halide particles can be produced almost simultaneously with the production of silver aliphatic carboxylate particles by coexisting with a component for forming a silver aliphatic carboxylate and injecting silver ions into the mixture. It is also possible to prepare a silver halide grain by reacting a silver salt of an aliphatic carboxylic acid with a halogen-containing compound and converting the silver salt of an aliphatic carboxylic acid. That is, a silver halide-forming component is allowed to act on a previously prepared solution or dispersion of a silver aliphatic carboxylate, or a sheet material containing the silver aliphatic carboxylate, to form a part of the silver aliphatic carboxylate. It can also be converted to photosensitive silver halide.

  Examples of silver halide grain forming components 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. Nos. 3,457,075, 4,003,749, British Patent No. 1,498,956, and JP-A-53-27027, and metal halides described in detail in JP-A-53-25420. And inorganic halides such as ammonium halides, for example, onium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, and trimethylbenzylammonium bromide, for example, iodoform, bromoform, carbon tetrachloride, 2-bromo- Halogenated hydrocarbons such as 2-methylpropane N-halogen compounds such as N-bromosuccinimide, N-bromophthalimide, N-bromoacetamide, and others, for example, triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, dichloroethanol Benzophenone and the like. As described above, the silver halide can also be prepared by converting a part or all of silver in the organic acid silver salt to silver halide by reacting the organic acid silver with the halide ion. Further, silver halide grains produced by converting a part of the silver salt of an aliphatic carboxylic acid to silver halide separately prepared may be used in combination.

  These silver halide grains, separately prepared silver halide grains, silver halide grains obtained by conversion of aliphatic carboxylic acid silver salt, 0.001 to 0.7 mole per mole of aliphatic carboxylic acid silver salt, Preferably, it is used in an amount of 0.03 to 0.5 mol.

  The separately prepared photosensitive silver halide grains are desalted by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, and an electrodialysis method, for example, in the desalting step. It can be used without desalting.

(Non-photosensitive silver aliphatic carboxylate)
Next, the non-photosensitive silver aliphatic carboxylate according to the present invention will be described.

  The non-photosensitive aliphatic carboxylic acid silver salt according to the invention is a reducible silver source, and is preferably a silver salt of a long-chain aliphatic carboxylic acid having 10 to 30 carbon atoms, preferably 15 to 25 carbon atoms. Examples of suitable silver salts include the following.

  For example, silver salts such as gallic acid, oxalic acid, behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid can be mentioned, and preferred silver salts include silver behenate, silver arachidate and silver stearate.

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

  On the other hand, from the viewpoint of the storage stability of the image after development, the aliphatic carboxylic acid as a raw material of the aliphatic carboxylic acid silver has a melting point of 50 ° C. or higher, preferably 60 ° C. or higher. It is preferable that the content ratio is 60% or more, preferably 70% or more, and more preferably 80% or more. From this viewpoint, specifically, it is preferable that the content of silver behenate is high.

  The aliphatic carboxylic acid silver salt compound can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and is described in a forward mixing method, a reverse mixing method, a simultaneous mixing method, and JP-A No. 9-127643. The controlled double jet method as described above 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 By the method, the soap and silver nitrate are mixed to prepare a crystal of a silver salt of an aliphatic carboxylic acid. At that time, silver halide grains may be mixed.

  The silver aliphatic carboxylate according to the present invention has a core / shell structure as disclosed in US Pat. No. 6,465,167, European Patent 1,168,069A1 and JP-A-2002-23303. Or dimers disclosed in European Patent No. 1,152,287 A2 and JP-A-2002-49119. When the core / shell structure is used, all or a part of either the core or the shell is made of an organic silver salt other than silver aliphatic carboxylate, for example, silver of an organic compound such as phthalic acid or benzimidazole. A salt may be used as a component of the crystal particles.

  In the aliphatic carboxylic acid silver salt according to the present invention, the average equivalent circle diameter is preferably 0.05 μm or more and 0.8 μm or less, and the average thickness is preferably 0.005 μm or more and 0.07 μm or less. Particularly preferably, the average equivalent circle diameter is 0.2 μm or more and 0.5 μm or less, and the average thickness is 0.01 μm or more and 0.05 μm or less.

  When the average equivalent circle diameter is 0.05 μm or less, transparency is excellent, but image storability is poor, and when the average equivalent circle diameter is 0.8 μm or more, devitrification is severe. When the average thickness is 0.005 μm or less, the surface area is large and silver ions are supplied rapidly during development. Especially in a low density portion, a large amount of silver ions remain in the film without being used for a silver image. In addition, image storability deteriorates remarkably. When the average thickness is 0.07 μm or more, the surface area is reduced and the image stability is improved, but silver supply during development is slow, and the developed silver shape becomes non-uniform, especially in a high-density portion. The concentration tends to be low.

  In order to determine the average equivalent circle diameter, the dispersed silver salt of aliphatic carboxylate is diluted and dispersed on a grid with a carbon support film, and is directly transmitted through a transmission electron microscope (for example, 2000FX type manufactured by JEOL Ltd.) at a magnification of 5000. The photograph is taken at a magnification of 2, and the negative is captured as a digital image by a scanner, and the average particle diameter can be calculated by measuring 300 or more particle diameters (equivalent circle diameter) using appropriate image processing software.

  The average thickness can be calculated by a method using a normal TEM (transmission electron microscope).

  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.

  As for the TEM 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. 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 created, and a portion corresponding to silver aliphatic carboxylate is extracted by binarization processing.

  The thickness of the extracted silver aliphatic carboxylate particles is manually measured with 300 or more suitable software, and the average value is determined.

  The method for obtaining the silver aliphatic carboxylate particles having the above-mentioned shape is not particularly limited, and examples thereof include a mixed state when forming an organic acid alkali metal salt soap and a mixed state when adding silver nitrate to the soap. It is effective to keep good, and to optimally set the ratio of organic acid to soap and the ratio of silver nitrate that reacts with soap.

  In the present invention, tabular aliphatic carboxylic acid silver salt particles (having an average equivalent circle diameter of 0.05 μm or more and 0.8 μm or less and an average thickness of 0.005 μm or more and 0.07 μm or less) are used. It is preferable that the acid silver salt particles are preliminarily dispersed together with a binder, a surfactant and the like, if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. As the predispersion method, for example, 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, for example, a ball mill, a planetary ball mill, a rolling mill such as a vibrating ball mill, a bead mill as a medium stirring mill, an attritor, and other basket mills can be used, and a high-pressure homogenizer can be used. Various types can be used, such as a type that collides with a wall, a plug, or the like, a type that divides a liquid into a plurality of liquids and then collides the liquids at a high speed, and a type that passes a thin orifice.

Examples of ceramics used for ceramic beads used at the time of media dispersion include Al ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , MgO, ZrO, BeO, Cr ₂ O ₃ , SiO ₂ , SiO ₂ —Al ₂ O ₃ , _{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), Preferred are Si ₂ O—nH ₂ O, silicon nitride, yttrium stabilized zirconia, zirconia reinforced alumina, and the like. Yttrium-stabilized zirconia and zirconia-reinforced alumina (these ceramics containing zirconia are hereinafter abbreviated as zirconia) are particularly preferably used because impurities generated due to friction with beads or a disperser during dispersion are small.

  In the apparatus used for dispersing the tabular aliphatic silver carboxylate particles according to the present invention, as the material of the member that the aliphatic silver carboxylate particles contact, for example, zirconia, alumina, silicon nitride, boron nitride It is preferable to use ceramics or diamond such as zirconia. When performing the above dispersion, the binder concentration is preferably 0.1 to 10% of the mass of the aliphatic silver carboxylate, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion to the main dispersion. Further, as preferable operating conditions of the main dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, the operating conditions are preferably 29 to 100 MPa, and the number of operations is two or more. When a media dispersing machine is used as the dispersing means, a preferable condition is a peripheral speed of 6 to 13 m / sec.

  In the present invention, the non-photosensitive silver aliphatic carboxylate particles are preferably formed in the presence of a compound functioning as a crystal growth inhibitor or a dispersant. Further, the compound functioning as a crystal growth inhibitor or a dispersant is preferably an organic compound having a hydroxyl group or a carboxyl group.

  In the present invention, in the step of producing silver aliphatic carboxylate particles, it is preferable to produce silver aliphatic carboxylate under conditions in which t-butanol or the like functioning as a dispersant is present, as described later. This is because it has a function of reducing the particle size and monodispersing as compared with the case where it is manufactured under the condition of not allowing coexistence, so that a higher covering power can be obtained.

  Alcohols having 10 or less carbon atoms, preferably secondary alcohols and tertiary alcohols, are monodispersed by increasing the solubility of sodium aliphatic carboxylate in the particle production process and increasing the stirring efficiency. And reduce the particle size. Branched aliphatic carboxylic acids and aliphatic unsaturated carboxylic acids have higher steric hindrance than linear aliphatic silver carboxylate, which is the main component when silver aliphatic carboxylate is crystallized, and the disorder of the crystal lattice is large. As a result, large crystals are not generated, and as a result, the particle size is reduced.

  The solution in the silver ion-containing solution referred to in the present invention means any solution, for example, an aqueous solution or a mixed aqueous solution with an organic solvent. As the organic solvent that can be used here, any one can be used as long as it is water-miscible, and those that adversely affect photographic performance are not preferred, and alcohol or acetone that can be mixed with water is preferable, and more preferably It is a tertiary alcohol, and more preferably a tertiary alcohol having 4 to 6 carbon atoms. As described above, the silver ion-containing solution may contain a tertiary alcohol having 4 to 6 carbon atoms. In this case, the volume is 70% or less based on the total volume of the aqueous solution of the water-soluble silver salt. And preferably 50% or less. Further, the temperature of the solution is preferably 0 ° C. or higher and 50 ° C. or lower, more preferably 5 ° C. or higher and 30 ° C. or lower, and as described below, an aqueous solution containing a water-soluble silver salt and an alkali metal salt of an aliphatic carboxylic acid. When the tertiary alcohol aqueous solution is added simultaneously, the temperature is most preferably 5 ° C. or more and 15 ° C. or less.

  The aliphatic carboxylic acid alkali salt used in the present invention is usually supplied in the form of a solution or suspension, preferably in the form of a solution. The solution referred to here is an arbitrary solution, for example, an aqueous solution, a mixed aqueous solution with an organic solvent, or an organic solvent solution. As the organic solvent that can be used here, any can be used, and those that adversely affect photographic performance are not preferred, and are preferably alcohols or acetone that can be mixed with water, and more preferably a tertiary alcohol. And more preferably a tertiary alcohol having 4 to 6 carbon atoms. When the alkali metal salt of the aliphatic carboxylic acid is supplied as a mixed aqueous solution with an organic solvent, the amount of the organic solvent used to obtain the uniformity of the liquid is 3% or more as the solvent volume with respect to the volume of water. , 70% or less, preferably 5% or more and 50% or less. At this time, since the optimum solvent volume changes depending on the reaction temperature, the optimum amount can be determined by trial and error.

  In the present invention, in order to form a silver salt of an aliphatic carboxylic acid, at least one of a silver ion solution, an alkali metal salt of an aliphatic carboxylic acid solution or a suspension, and a solution previously prepared in a reaction field is used. It is preferable that the alkali metal salt of the aromatic carboxylic acid contains an organic solvent in an amount capable of forming a substantially transparent solution instead of a string-like aggregate or micelle. The pH of the silver ion-containing solution or the aliphatic carboxylic acid alkali metal salt solution or suspension to be added can be adjusted according to the required properties of the particles. An arbitrary acid or alkali can be added for pH adjustment. Further, depending on the required characteristics of the particles, for example, the temperature in the reaction vessel can be arbitrarily set for controlling the particle size of the aliphatic silver carboxylate to be prepared. The alkali metal carboxylate solution or suspension can also be adjusted to any temperature. The aliphatic carboxylic acid alkali metal salt solution or suspension is preferably heated and kept at 50 ° C. or higher in order to secure the fluidity of the solution. The silver aliphatic carboxylate used in the present invention is preferably prepared in the presence of a tertiary alcohol. The tertiary alcohol used in the present invention preferably has a total carbon number of 15 or less, particularly preferably 10 or less. Preferred examples of the tertiary alcohol include t-butanol and the like, but the present invention is not limited thereto.

The tertiary alcohol used in the present invention may be added at any time during the preparation of the silver aliphatic carboxylate. It is preferable to use it after dissolving it. The amount of the tertiary alcohol can be arbitrarily used in a mass ratio of 0.01 to 10 with respect to H ₂ O as a solvent at the time of preparing the silver aliphatic carboxylate. The range of ~ 1 is preferable. In the present invention, the scaly silver salt of an aliphatic carboxylic acid is preferably prepared by reacting an aqueous solution containing a water-soluble silver salt with an aqueous tertiary alcohol solution containing an alkali metal salt of an aliphatic carboxylic acid in a reaction vessel. A step of adding an aqueous solution of a tertiary alcohol containing an alkali metal salt of an aliphatic carboxylic acid to the solution of (1), wherein a solution (preferably an aqueous solution containing a water-soluble silver salt previously added, Alternatively, when an aqueous solution containing a water-soluble silver salt is simultaneously added from the beginning with an aqueous tertiary alcohol solution containing an alkali metal salt of an aliphatic carboxylic acid without prior addition, water or water and a tertiary alcohol are added as described later. Water or a mixed solvent of water and a tertiary alcohol may be added in advance even when an aqueous solution containing a water-soluble silver salt is added in advance.) The temperature difference between the tertiary alcohol solution containing aliphatic carboxylic acid alkali metal salts are preferably prepared in a way that the 85 ° C. or less 20 ° C. or higher.

  By maintaining such a temperature difference during the addition of the tertiary alcohol aqueous solution containing the aliphatic carboxylic acid alkali metal salt, the crystal form of the aliphatic carboxylic acid silver salt is preferably controlled. The aqueous tertiary alcohol solution of the alkali metal salt of an aliphatic carboxylic acid used in the present invention is preferably a mixed solvent of a tertiary alcohol having 4 to 6 carbon atoms and water in order to obtain a uniform liquid. If the carbon number exceeds this, there is no compatibility with water, which is not preferable. Among the tertiary alcohols having 4 to 6 carbon atoms, t-butanol, which is most compatible with water, is most preferable. Alcohols other than tertiary alcohols are not preferred because they have a reducing property and cause adverse effects when silver salts of aliphatic carboxylic acids are formed. The amount of the tertiary alcohol used in the tertiary alcohol aqueous solution of the alkali metal salt of the aliphatic carboxylic acid is 3% or more and 70% or less as the solvent volume with respect to the volume of water in the tertiary alcohol aqueous solution. , Preferably 5% or more and 50% or less.

  The concentration of the alkali metal salt of the aliphatic carboxylic acid in the aqueous tertiary alcohol solution of the alkali metal salt of the aliphatic carboxylic acid used in the present invention is 7% by mass or more and 50% by mass or less as a mass ratio, and preferably 7% by mass or less. % To 45% by mass, more preferably 10% to 40% by mass. The temperature of the tertiary alcohol aqueous solution of the alkali metal salt of an aliphatic carboxylic acid to be added to the reaction vessel is set at 50 ° C. for the purpose of keeping the temperature necessary to avoid the crystallization and solidification of the alkali metal salt of an aliphatic carboxylic acid. The temperature is preferably from 90 ° C to 90 ° C, more preferably from 60 ° C to 85 ° C, most preferably from 65 ° C to 85 ° C. Further, in order to control the temperature of the reaction to be constant, it is preferable to control the temperature to be constant at a certain temperature selected from the above range.

  In the production method of the present invention, in order to control the shape of the formed aliphatic carboxylic acid silver salt, the silver ion solution and the aliphatic carboxylic acid alkali metal salt solution are adjusted to appropriate temperatures. The temperature of the silver ion solution is preferably 5 ° C. or more and 60 ° C. or less, more preferably 5 ° C. or more and 40 ° C. or less, for the purpose of ensuring the stability of the solution. The aliphatic carboxylic acid alkali metal salt solution is preferably at least 50 ° C. and at most 90 ° C., more preferably at least 60 ° C. and at most 85 ° C., for the purpose of maintaining the temperature necessary for avoiding the phenomenon of alkali soap crystallization and solidification. It is as follows. Further, the silver ion-containing solution, the solution or suspension of an alkali metal salt of an aliphatic carboxylic acid used in the present invention, or the solution in a reaction vessel to which both solutions are added may be, for example, a compound represented by the general formula of JP-A-62-65035. A compound represented by (1), a water-soluble group-containing N-heterocyclic compound as described in JP-A-62-150240, an inorganic peroxide as described in JP-A-50-101019, Sulfur compounds described in JP-A-51-78319, disulfide compounds described in JP-A-57-643, and hydrogen peroxide can be added. In the present invention, the temperature of the reaction solution during silver salt formation needs to be maintained at 5 ° C. or higher and 60 ° C. or lower, more preferably 10 ° C. or higher and 50 ° C. or lower, further preferably 20 ° C. or higher and 45 ° C. or lower. Keep below. By maintaining such a reaction temperature, the performance as a photographic light-sensitive material can be further improved.

  In the present invention, silver aliphatic carboxylate is usually prepared by reacting a solution or suspension of an alkali metal salt of an aliphatic carboxylic acid (including Na salt, K salt, Li salt and the like) with a silver ion-containing solution. You. The preparation of the silver aliphatic carboxylate can be carried out batchwise or continuously in any suitable vessel. The stirring in the reaction vessel can be performed by any stirring method depending on the required properties of the particles. As a method for preparing silver aliphatic carboxylate, a method in which a silver ion-containing solution is gradually or rapidly added to a reaction vessel containing an alkali metal salt of an aliphatic carboxylic acid solution or a suspension, or a method in which a silver ion-containing solution is added. A method in which a previously prepared alkali metal salt of an aliphatic carboxylic acid solution or suspension is gradually or rapidly added to a reaction vessel. Any of the methods of simultaneous addition into a container can be preferably used. The silver ion-containing solution and the aliphatic carboxylic acid alkali metal salt solution or suspension may be of any concentration for controlling the particle size of the prepared aliphatic silver carboxylate. (As described above in the specification), and can be added at any rate. The silver ion-containing solution and the aliphatic carboxylic acid alkali metal salt solution or suspension can be added by a method of adding at a constant addition rate, an accelerated addition method by an arbitrary time function, or a deceleration addition method. . Further, it may be added to the liquid surface or may be added to the reaction solution. In the case of a method in which a previously prepared silver ion-containing solution and an aliphatic carboxylic acid alkali metal salt solution or suspension are simultaneously added into a reaction vessel, a silver ion-containing solution or an aliphatic carboxylic acid alkali metal salt solution or suspension is added. Although any of the liquids can be added in advance, it is preferable to add the silver ion-containing solution in advance. The leading degree is preferably from 0 to 50% by volume, particularly preferably from 0 to 25% by volume of the total amount. Also, a method of adding while controlling the pH or silver potential of the reaction solution during the reaction as described in JP-A-9-127463 can be preferably used.

  When an aqueous tertiary alcohol solution of an alkali metal salt of an aliphatic carboxylic acid is used in the present invention, the silver salt of an aliphatic carboxylic acid can be obtained by: A method in which a tertiary alcohol aqueous solution of an acid alkali metal salt is single-added, or ii) a period in which a silver ion-containing solution and an aqueous solution of a tertiary alcohol of an aliphatic carboxylic acid alkali metal salt are simultaneously added to a reaction vessel. (Simultaneous addition method). In the present invention, from the viewpoint of controlling the average particle size of the aliphatic carboxylic acid silver salt and narrowing the distribution, the latter method of simultaneous addition is preferred. In this case, it is preferable that 30% by volume or more of the total amount is simultaneously added, and more preferably 50 to 75% by volume is added simultaneously. When either of them is added in advance, it is preferable to add a silver ion-containing solution first. In any case, the liquid in the reaction vessel (when the silver ion-containing solution previously added or the silver ion-containing solution is not previously added as described above, The temperature is preferably 5 ° C. or more and 75 ° C. or less, more preferably 5 ° C. or more and 60 ° C. or less, and most preferably 10 ° C. or more and 50 ° C. or less. The temperature is preferably controlled to a certain temperature selected from the above temperatures throughout the entire process of the reaction, but it is also preferable to control the temperature in several temperature patterns within the above temperature range.

  When an aqueous tertiary alcohol solution of an alkali metal salt of an aliphatic carboxylic acid is used in the present invention, the temperature difference between the aqueous solution of a tertiary alcohol of an alkali metal salt of an aliphatic carboxylic acid and the solution in the reaction vessel is 20 ° C. As described above, the temperature is preferably 85 ° C or lower, more preferably 30 ° C or higher and 80 ° C or lower. In this case, the temperature of the aqueous tertiary alcohol solution of the alkali metal salt of the aliphatic carboxylic acid is preferably higher. Thereby, the rate at which the tertiary alcohol aqueous solution of the alkali metal salt of the aliphatic carboxylic acid at a high temperature is rapidly cooled in the reaction vessel and precipitates in the form of microcrystals, and the rate at which the aliphatic carboxylic acid is converted into the silver salt with the silver ion by the reaction with silver ions, are preferable. Thus, the crystal form, crystal size, and crystal size distribution of the aliphatic carboxylic acid silver salt can be preferably controlled. At the same time, the performance as a heat-developable recording material, particularly a heat-developable photosensitive material, can be further improved. A solvent may be contained in the reaction vessel in advance, and water is preferably used as the solvent to be put in advance, but a mixed solvent with the tertiary alcohol is also preferably used.

(Anti-fogging agent and image stabilizer)
Hereinafter, the antifoggant and image stabilizer used in the silver salt photothermographic dry imaging material of the present invention will be described.

  In the silver salt photothermographic dry imaging material of the present invention, as the reducing agent, it is preferable to use mainly bisphenols as the reducing agent, as described later, but an active species capable of extracting hydrogen from these reducing agents is used. It is preferable that a compound capable of inactivating the reducing agent by generating the 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.

  Therefore, any compound may be used as long as it has these functions, but an organic free radical consisting of 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 silver salt photothermographic dry imaging material.

  Compounds that generate these free radicals may be carbocyclic or heterocyclic in order to have sufficient stability that the generated free radicals can be contacted for a sufficient time to react with and inactivate the reducing agent. Those having an aromatic group are preferred.

Representative examples of these compounds include the following biimidazolyl compounds and iodonium compounds. These preferred specific examples include, for example, compound examples described in JP-A-2000-321711. The addition amount of these compounds is 10 ^-3 to 10 ^-1 mol / m ² , preferably 5 × 10 ^{-3 to} 5 × 10 ^-2 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.

  Further, as the compound that inactivates the reducing agent and prevents the reducing agent from reducing the silver salt of the aliphatic carboxylic acid to silver, a compound in which the reactive species is not a halogen atom is preferable, but a compound that releases a halogen atom as an active species is preferable. Can also be used in combination with a compound that releases an active species that is not a halogen atom. 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.

  In addition to the above compounds, the silver salt photothermographic dry imaging material of the present invention may contain a compound conventionally known as an antifoggant. Or a compound having a different antifogging mechanism. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. No. 4,756,999, JP-A-9-288328 and JP-A-9-90550. Further, other antifoggants include compounds disclosed in U.S. Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981 and 631,176. .

  In the present invention, as an antifoggant and an image stabilizer, in addition to the above compounds, compounds capable of forming a chelate ring with silver ions, for example, having two carboxyl groups at adjacent positions such as phthalic acids And a compound capable of forming a chelate ring with silver ions can also be preferably used.

  In the present invention, at least one of the silver ion reducing agents is preferably a bisphenol derivative, and can be used alone or in combination with other reducing agents having different chemical structures. In the silver salt photothermographic imaging material according to the present invention, it is possible to unexpectedly suppress performance deterioration due to fogging or the like in storage of the silver salt photothermographic dry imaging material and color deterioration in storage of the silver image after thermal development. it can.

(Silver ion reducing agent)
Hereinafter, the reducing agent that can be used in the present invention will be described.

  Examples of suitable reducing agents incorporated in the silver salt photothermographic dry imaging material of the present invention are described in U.S. Patent Nos. 3,770,448, 3,773,512, 3,593,863, and Research Disclosure (hereinafter sometimes abbreviated as RD) No. No. 17029 and the same No. 29963, which can be appropriately selected from known reducing agents and used. When an aliphatic silver carboxylate is used as the organic silver salt, two or more phenol groups are alkylene groups. A polyphenol linked by a group or sulfur, especially an alkyl group (e.g., methyl, ethyl, propyl, t-butyl, cyclohexyl, etc.) at at least one of the positions adjacent to the hydroxy-substituted position of the phenol group or Bisphenols in which two or more phenol groups substituted with an acyl group (for example, an acetyl group or a propionyl group) are linked by an alkylene group or sulfur can be used.

  Particularly, the reducing agent preferably used in the present invention includes a reducing agent represented by the following general formula (A-1), more preferably a general formula (A-2), a general formula (A-4) or a general formula (A-5) ) Is used.

  In the general formula (A-1), Z represents an atomic group necessary to form a 3- to 10-membered ring together with a carbon atom, and Z represents a 3- to 10-membered non-aromatic ring or a 5- to 6-membered aromatic ring. It is preferably a ring, and more preferably a 3- to 10-membered non-aromatic ring. Specifically, the three-membered ring is cyclopropyl, aziridyl, oxiranyl, the four-membered ring is cyclobutyl, cyclobutenyl, oxetanyl, azetidinyl, and the five-membered ring is cyclopentyl, cyclopentenyl, cyclopentadienyl, tetrahydrofuranyl, pyrrolidinyl , Tetrahydrothienyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, tetrahydropyranyl, pyranyl, piperidinyl, dioxanyl, tetrahydrothiopyranyl, norcalanyl, norpinanyl, norbornyl as the 6-membered ring, cycloheptyl, cycloheptynyl, cyclo Heptadienyl, 8-membered ring is cyclooctanyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, 9-membered ring is cyclononanyl Cyclononenyl, shea chrono Nagy enyl, cyclononatrienyl enyl, as the 10-membered ring cyclooctyl, Shikurodekeniru, cycloalkyl decadienyl include the group such as cyclopropyl tetradecatrienyl.

  It is preferably a 3- to 6-membered ring, more preferably a 5- to 6-membered ring, and 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. Further, 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 group For example, acetyloxy group and the like, alkylthio group (for example, methylthio group, trifluoromethylthio group and the like), carboxyl group, alkylcarbonylamino group (for example, acetylamino group and the like), ureido group (for example, methylaminocarbonylamino group and the like) ), An alkylsulfonylamino group (eg, methanesulfonylamino group), an alkylsulfonyl group (eg, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), a 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 group, cyano group, alkyl sulfone (E.g., methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group (e.g., 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.), alkynylamino ++ carbonyl 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.

  Next, the case where Z is a 5- to 6-membered aromatic cyclic group will be described. The aromatic carbocyclic ring may be a single ring or a condensed ring, preferably a monocyclic or bicyclic aromatic carbon ring having 6 to 30 carbon atoms (for example, a benzene ring, a naphthalene ring, etc.). A benzene ring is preferably used. The aromatic hetero ring is preferably a 5- to 6-membered aromatic hetero ring optionally having a condensed ring. More preferably, it is a 5-membered aromatic hetero ring optionally having a condensed ring. As such a hetero ring, preferably, imidazole, pyrazole, thiophene, furan, pyrrole, 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, pyrazole, thiophene, furan, pyrrole, Triazole, thiadiazole, tetrazole, thiazole, benzimidazole, benzothiazole, especially Mashiku thiophene, furan, thiazole. The ring may be condensed in any manner with other rings, including aromatic rings. Further, the ring may have any substituent. Examples of the substituent include the same substituents as described above on the 3- to 10-membered non-aromatic cyclic group. When Z is a 5- to 6-membered aromatic cyclic group, most preferred is a 5-membered aromatic heterocyclic group.

R ₁ and R ₂ represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, and 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. R ₁ is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a cyclohexyl group, a 1-methylcyclohexyl group, or the like. More preferred are a methyl group, a t-butyl group, and a 1-methylcyclohexyl group, and most preferred are a t-butyl group and a 1-methylcyclohexyl group. R ₂ is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a 2-hydroxyethyl group, or the like. More preferably, they are a methyl group and a 2-hydroxyethyl group. Specific examples of the aryl group represented by R ₁ and R ₂ include a phenyl group, a naphthyl group, and an anthranyl group. Specific examples of the heterocyclic groups represented by R ₁ and R ₂ include pyridine, quinoline, isoquinoline, imidazole, pyrazole, triazole, oxazole, thiazole, oxadiazole, thiadiazole, and tetrazole. And a non-aromatic heterocyclic group such as a piperidino group, a morpholino group, a tetrahydrofuryl group, a tetrahydrothienyl group, and a tetrahydropyranyl group. These groups may further have a substituent, and examples of the substituent include the aforementioned substituents on the ring.

In the most preferred combination of R ₁ and R ₂ , R ₁ is a tertiary alkyl group (eg, t-butyl group, 1-methylcyclohexyl group, etc.), and R ₂ is a primary alkyl group (eg, methyl group, 2- Hydroxyethyl group).

R _X represents a hydrogen atom, an alkyl group, an alkenyl group or an alkynyl group, and specifically, it 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 thereof include a cycloalkenyl group, a 2-cycloalkenyl group, an ethynyl group, and a 1-propynyl group. 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 t-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 (chlorine atom) , Bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy group, etc.) ), Alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butane Sulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylamido group) A nosulfonyl group, a hexylaminosulfonyl group, a cyclohexylaminosulfonyl group, a phenylaminosulfonyl group, a 2-pyridylaminosulfonyl group, etc., a urethane group (a methylureido group, an ethylureido group, a pentylureido group, a cyclohexylureido group, a phenylureido group, 2-pyridylureido group, etc.), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylamino) Carbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc., amide group (acetone) Amide 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 aryl group, or It represents 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. 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 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 a group of atoms necessary for forming a 3- to 10-membered non-aromatic ring together with a carbon atom and G, and the 3- to 10-membered non-aromatic ring is represented by the above-mentioned 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).

  Next, the reducing agent represented by formula (A-4) or (A-5) according to the present invention will be described.

In the general formula (A-4), R ₄₀ represents the general formula (A), but R _{43 to} R ₄₅ each represent a hydrogen atom or a substituent. Examples of the substituent represented by R _{43 to} R ₄₅ include an alkyl group, (methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, sec-butyl, t-butyl, cyclohexyl, 1-methyl-cyclohexyl, etc. Each group), alkenyl group (each group such as vinyl, propenyl, butenyl, pentenyl, isohexenyl, cyclohexenyl, butenylidene, isopentylidene), alkynyl group (each group such as ethynyl, propynylidene), aryl group (phenyl, naphthyl) Other groups), a heterocyclic group (each group such as furyl, thienyl, pyridyl, tetrahydrofuranyl, etc.), halogen, hydroxyl, alkoxy, aryloxy, acyloxy, sulfonyloxy, nitro, amino, acylamino, sulfonylamino, Sulfonyl, carboxy And groups such as silyl, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, cyano, and sulfo.

When C in the general formula (A) does not form a ring with any of R _{43 to} R ₄₅ , R ₄₀ is at least one optionally substituted ethylene group (2,6-dimethyl-5-heptenyl, 1, 5-dimethyl-4-hexenyl) or an optionally substituted acetylene group (such as 1-propynyl).

When C in the general formula (A) forms a ring (phenyl, naphthyl, furyl, thienyl, pyridyl, cyclohexyl, cyclohexenyl, etc.) with any of R _{43 to} R ₄₅ , R ₄₀ has at least one It contains an optionally substituted ethylene group (vinyl, propenyl, acryloxy, methacryloxy, etc.) or an optionally substituted acetylene group (ethynyl, acetylenecarbonyloxy, etc.).

R ₄₁ , R ₄₁ ′, R ₄₂ , R ₄₂ ′, X ₄₁ and X ₄₁ ′ each represent a hydrogen atom or a substituent, and the substituents are the same as those described in the description of R _{43 to} R _45. Groups.

R ₄₁ , R ₄₁ ′, R ₄₂ and R ₄₂ ′ are preferably alkyl groups, and specific examples include the same groups as the examples of the alkyl groups mentioned in the description of R _{43 to} R ₄₅ .

In Formula (A-5), R ₅₀ represents a hydrogen atom or a substituent, and examples of the substituent include groups similar to the substituents described in the description of R _{43 to} R _{45 in} Formula (A). No. R ₅₀ is preferably a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group, and more preferably a hydrogen atom or an alkyl group.

R ₅₁ , R ₅₁ ′, R ₅₂ , R ₅₂ ′, X ₅₁ and X ₅₁ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include those described for R _{43 to} R _{45 in} formula (A). And the same groups as the substituents described above.

R ₅₁ , R ₅₁ ′, R ₅₂ and R ₅₂ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group and the like. Specifically, the alkyl groups, alkenyl groups, and alkynyl groups described in the description of R _{43 to} R ₄₅ are preferable. Examples include the same groups as the examples of the group.

Provided that at least one of R ₅₁ , R ₅₁ ′, R ₅₂ , R ₅₂ ′, X ₅₁ and X ₅₁ ′ may be substituted with an ethylene group (eg, vinyl, allyl, methacryloxymethyl) or an optionally substituted acetylene group (Ethynyl, propargyl, propargyloxycarbonyloxymethyl, etc.).

  In the present invention, it is preferable to use a compound represented by the general formula (A-1) in combination with a compound represented by the following general formula (A-3). 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 or an alkenyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. -20 alkyl groups are preferred. Specific examples of the alkyl group include, for example, methyl group, ethyl group, propyl group, butyl group, hexyl group, heptyl group and the like, and alkenyl groups include vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl -2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group and the like.

  These groups may further have a substituent, and as the substituent, the substituents described in General Formula (A-1) can be used. 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, and 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.

Although the substituent of the alkyl group is not particularly limited, for example, 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 Carbamoyl group, ester group, halogen atom and the like. Further, (Q ₀ ) _n and (Q ₀ ) _m may form a saturated ring. R ₃ 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 fluorine atom, a chlorine atom, a halogen atom such as 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, the substituents described in General Formula (A-1) can be used. 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.

  Hereinafter, specific examples of the compounds represented by formulas (A-1) to (A-5) of the present invention are listed, but the present invention is not limited thereto.

  The compounds represented by formulas (A-1), (A-2) and (A-3) of the present invention 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.

  The compounds represented by formulas (A-4) and (A-5) of the present invention can be synthesized by the following methods.

  According to the above scheme, a phenol derivative and an aldehyde derivative are treated with a catalyst such as hydrochloric acid, sulfuric acid, p-toluenesulfonic acid in a solvent such as water, methanol, ethanol, acetonitrile, tetrahydrofuran, ethyl acetate, toluene, N, N-dimethylformamide. Can be used to synthesize a compound represented by the general formula (A-4) or (A-5).

  The reducing agent contained in the silver salt photothermographic dry imaging material reduces an organic silver salt to form a silver image. Examples of the reducing agent that can be used in combination with the reducing agent of the present invention include, for example, U.S. Pat. Nos. 3,770,448, 3,773,512, 3,593,863, RD17029 and 29963, and -119372, JP-A-2002-62616 and the like.

The amount of the reducing agent including the compounds represented by the general formulas (A-1) to (A-5) is preferably 1 × 10 ⁻² to 10 mol, particularly preferably 1 × 10 ⁻² mol per mol of silver. 10 ^{-2 to} 1.5 mol.

(binder)
Hereinafter, the binder that can be used in the present invention will be described.

  The light-sensitive material of the present invention has a light-sensitive layer containing a light-sensitive silver halide on at least one surface of a support, and further has at least one non-light-sensitive layer. The non-photosensitive layer is formed by simultaneous drying after the application layer. In this case, a polymer latex is used as a main binder of the photosensitive layer of the present invention. When the polymer latex used in the present invention is applied to the main binder of the photosensitive layer, the diffusion rate of the toning agent that generates a silver carrier during heat development is reduced, and the silver ion is reduced on the silver halide particles serving as a catalyst. When the range of the non-photosensitive aliphatic carboxylic acid silver salt, which is the supply source of silver consumed there, is calculated in terms of a sphere centering on the latent image of, this radius is often small. That is, it is considered that, since the range of influence is narrowed, the size of the developed silver is reduced and the covering power is increased.

  The polymer of such a polymer latex preferably has an equilibrium water content at 25 ° C. and 60% RH of 2% by mass or less.

  The non-photosensitive layer that is dried at the same time as the photosensitive layer according to the invention is a layer other than the photosensitive layer among the layers constituting the photosensitive material of the invention, and is a layer formed using a coating solution of an aqueous solvent. is there.

  Therefore, in the present invention, in two or more layers including the photosensitive layer and the non-photosensitive layer, coating using an aqueous solvent as a coating solvent becomes possible, which is advantageous in terms of environment and cost as compared with coating with an organic solvent. It becomes. Further, since two or more layers are formed simultaneously by drying, the coated surface state and the productivity are excellent.

  Further, since the polymer latex is used, generation of fog in a high humidity atmosphere is suppressed.

  As a conventional binder for an aqueous solvent, gelatin and polyvinyl alcohol are generally used, but the equilibrium water content of such a polymer under the above-mentioned conditions is more than 2% by mass, and the fog increases in a high humidity atmosphere. Is seen.

  The use of gelatin as a binder in the non-photosensitive layer, and particularly the use of gelatin as a binder in the surface protective layer, has a great effect of improving the coated surface condition of the surface of the photosensitive material, which is practically preferable.

  Regarding the coated surface state, for example, a so-called sequential drying method in which a photosensitive layer is formed by coating and drying, and then a non-photosensitive layer on the photosensitive layer side of the support such as a surface protective layer is formed by coating and drying. The simultaneous drying method is more advantageous than the above.

  As described above, the present invention is advantageous in terms of environment and cost, can employ an efficient production method by a simultaneous drying method, and can reduce fog in a high-humidity atmosphere, and It has the characteristic that the coating surface condition can be improved.

  The polymer latex referred to in 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.

  The polymer latex of the present invention is described in "Synthetic Resin Emulsion" (edited by Hira Okuda and Hiroshi Inagaki, published by Kobunshi Kanko (1978)), and "Application of Synthetic Latex" (Takaaki Sugimura, Yasuo Kataoka, Soichi Suzuki, Keiji Kasahara) , Published by Kobunshi Kankokai (1993)), "Synthesis of Synthetic Latex (Souichi Muroi, published by Kobunshi Kankokai (1970))" and the like. The average particle size of the dispersed particles of the polymer latex is preferably in the range of 1 to 50,000 nm, more preferably in the range of about 5 to 1,000 nm. There is no particular limitation on the particle size distribution of the dispersed particles.

  Examples of polymer species used in the polymer latex of the present invention include acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, vinylidene chloride resins, rubber resins (eg, SBR resins and NBR resins), vinyl acetate resins, polyolefin resins, Examples include polyvinyl acetal resin.

  The polymer may be a homopolymer in which a single monomer is polymerized, or a copolymer in which two or more polymers are polymerized. The polymer may be a linear or branched polymer. Further, the polymers may be crosslinked. In the case of a copolymer, it may be random, alternating, block, or the like.

  As the molecular weight of the polymer, those having a number average molecular weight Mn of 1,000 to 1,000,000, preferably 3,000 to 500,000 are desirable. Those having a number average molecular weight of less than 1,000 generally have low film strength after coating, and may cause inconvenience such as cracking of the photosensitive layer.

  The equilibrium water content at 25 ° C. and 60% RH of the polymer of the present invention is preferably required to be 2% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, still more preferably. The content is desirably 0.03% by mass or more and 1% by mass or less.

The “equilibrium water content at 25 ° C. and 60% RH” referred to in the present invention refers to the mass W _{1 of} a polymer that is in a moisture-conditioning equilibrium in an atmosphere of 25 ° C. and 60% RH and the mass W ₁ of a polymer that is in an absolutely dry state at 25 ° C. It can be expressed as follows using ₀ .

Equilibrium water content at 25 ° C. and 60% RH = {(W ₁ −W ₀ ) / W ₀ } × 100 (% by mass)
For the actual method of measuring the equilibrium moisture content, for example, “Polymer Engineering Course 14, Polymer Material Testing Method (edited by the Society of Polymer Science, Chijin Shokan)” or the like can be referred to.

  Specific examples of the polymer latex for the main binder of the photosensitive layer according to the invention include the following.

_{P-1 :-( MMA) 60 -} (EA) 35 - (MAA) 5 - latex (Mn = 5 50,000)
_{P-2 :-( MMA) 50 -} (2EHA) 30 - (St) 17 - (MAA) 3 - latex (Mn = 5 50,000)
_{P-3 :-( St) 70 -} (Bu) 25 - (MAA) 5 - latex (Mn = 3 50,000)
_{P-4 :-( St) 65 -} (Bu) 27 - (DVB) 5 - (AA) 3 - latex (Mn = 12 50,000)
_{P-5 :-( VC) 50 -} (MMA) 45 - (AA) 5 - latex (Mn = 2 50,000)
_{P-6 :-( VDC) 70 -} (MMA) 20 - (EA) 7 - (MAA) 3 - latex (Mn = 9 50,000)
In the above, abbreviations represent structural units derived from the following monomers, and numerical values are% by mass.

MMA: methyl methacrylate, EA: ethyl acrylate, MAA: methacrylic acid, 2EHA: 2-ethylhexyl acrylate, St: styrene, Bu: butadiene, DVB: divinylbenzene, AA: acrylic acid, VC: vinyl chloride, VDC: vinylidene chloride Such polymers are also commercially available and the following can be used as the polymer latex of the present invention.

  For example, acrylic resins such as Sebian A-4635, 46583, 4601 (manufactured by Daicel Chemical Industries, Ltd.) and Nipol LX811, 814, 820, 821, 857 (manufactured by Nippon Zeon Co., Ltd.); HYDRAN AP10, 20, 30, 40 such as, FINETEX ES650, 611, 679, 675, 525, 801, 850 (all manufactured by Dainippon Ink and Chemicals, Inc.) and WDsize WHS (manufactured by Eastman Chemical). , 101H, HYDRAN HW301, 310, and 350 (all manufactured by Dainippon Ink and Chemicals, Inc.). Examples of vinylidene chloride resins include L502, L513, L123c, L106c, L111, and L114 (all manufactured by Asahi Kasei Corporation). With vinyl chloride resin For example, rubber-based resins such as G351 and G576 (manufactured by Nippon Zeon Co., Ltd.) include LACSTAR3307B, 7132C, DS206 (manufactured by Dainippon Ink and Chemicals, Inc.), Nipol Lx416, Lx433 (manufactured by Nippon Zeon Co., Ltd.) Polyolefin resins such as Chemipearl S-120, S-300, SA-100, A-100, V-100, V-200, V-300 (all manufactured by Mitsui Petrochemical Co., Ltd.). is there.

  In the binder of the present invention, these polymers may be used alone as a polymer latex, or may be used by blending two or more kinds.

  As the polymer latex used in the present invention, a styrene-butadiene copolymer latex is particularly preferable. The molar ratio between the styrene monomer unit and the butadiene monomer unit in the styrene-butadiene copolymer is preferably from 50:50 to 95: 5, more preferably from 60:40 to 90:10. The proportion of the copolymer of the styrene monomer unit and the butadiene monomer unit in the copolymer is preferably 50 to 99% by mass, more preferably 60 to 97% by mass. The preferred molecular weight range is the same as described above.

  Examples of the styrene-butadiene copolymer latex preferably used in the present invention include the above-mentioned P-3 and P-4, and commercially available products such as LACSTAR3307B, 7132C, DS206, Nipol Lx416, Lx433, and the like.

  The aqueous solvent in which the polymer of the present invention is soluble or dispersible in the present invention is water or a mixture of water and 70% by mass or less of a water-miscible organic solvent. Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; ethyl acetate; and dimethylformamide.

  Note that the term "aqueous solvent" is used herein even in a system in which the polymer is not thermodynamically dissolved but exists in a so-called dispersed state.

  The polymer latex described above is used as a main binder in the photosensitive layer of the present invention. The main binder as used herein means "a state in which the polymer derived from the polymer latex accounts for 50% by mass or more of the total binder in the photosensitive layer". The content is more preferably 70% by mass or more, and it is also preferable to use only the polymer latex of the present invention. When two or more types are used, the total amount is used.

  Therefore, the photosensitive layer of the present invention may contain a polymer derived from the polymer latex in an amount of 50% by mass or less, more preferably 30% by mass or less, particularly less than 30% by mass, more preferably 20% by mass or less of the total binder. . Preferred examples of these polymers include gelatin and polyvinyl alcohol.

  By using the polymer latex of the present invention in the above ratio in the photosensitive layer of the present invention, the equilibrium water content of the polymer mixture at 25 ° C. and 60% RH is preferably 2% by mass or less.

  The amount of the binder in the photosensitive layer of the present invention is preferably from 10: 1 to 200: 1, more preferably from 20: 1 to 100: 1 by mass ratio in terms of the ratio of the binder to the photosensitive silver halide.

  In the present invention, the photosensitive layer is formed using a coating solution. The solvent for the coating solution is a water solvent containing 30% by mass or more of water, and in addition to water, a water-miscible organic solvent as described above. Water (100), a water / methanol system, for example, water (90) / methanol (10), water (70) / methanol (30), water (60) ) / Methanol (40), water (50) / methanol (50), water / methanol / isopropyl alcohol system such as water (80) / methanol (10) / isopropyl alcohol (10), water / dimethylformamide system such as water (95) / dimethylformamide (5), water / ethyl acetate system, for example, water (96) / ethyl acetate (4), water / methanol / butyl cellosolve system, for example, water (80) / meta Like Lumpur (10) / butyl cellosolve (10) (where numeric values indicate mass%). Among them, a solvent containing 70% by mass or more of water is preferable.

(Image color tone and its evaluation method)
Next, the color tone of an image obtained by subjecting the imaging material to heat development will be described.

  With respect to the color tone of an output image for medical diagnosis such as a conventional radiographic film, it is said that a cooler tone is easier for a reader to obtain a more accurate diagnostic observation result of a recorded image. Here, the cool image tone is a pure black tone or a blue-black tone in which a black image has a bluish tint, and the warm tone image tone is a warm black tone in which a black image has a brown tint. However, in order to allow a more rigorous quantitative discussion, the following description is based on the expression recommended by the International Commission on Illumination (CIE).

The terms “cooler” and “warmer” regarding the color tone can be expressed by the hue angle “hab” at the minimum density Dmin and the optical density D = 1.0. That is, the hue angle hab uses the color coordinates a ^* , b ^* of the L ^* a ^* b ^* color space, which is a color space having a perceptually nearly equal rate recommended by the International Commission on Illumination (CIE) in 1976. Is obtained by the following equation.

hab = tan ^-1 (b ^* / a ^* )
As a result of examination by the expression method based on the hue angle, the color tone after development of the silver halide photothermographic imaging material according to the present invention is preferably such that the range of the hue angle hab is 180 degrees <hab <270 degrees, more preferably. Was found to be 200 degrees <hab <270 degrees, most preferably 220 degrees <hab <260 degrees. This is disclosed in JP-A-2002-6463.

Conventionally, u ^* , v ^* or a ^* , b ^* in the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space near the optical density of 1.0 is specified. It is known that a diagnostic image having a preferable visual tone can be obtained by adjusting the value to a numerical value. For example, it is described in JP-A-2000-29164.

However, the silver salt photothermographic imaging material according to the present invention has been further studied, and as a result, the horizontal axis in the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space is u ^* or a ^* , u ^* , v ^* or a ^* , b ^* at various photographic densities are plotted on a graph whose vertical axis is v ^* or b ^* , and a linear regression line is created. It has been found that by adjusting the ratio to a specific range, the diagnostic performance is equal to or better than that of a conventional wet silver salt photosensitive material. Hereinafter, a preferable condition range will be described.

(1) The optical densities 0.5, 1.0, 1.5 and the minimum optical density of the silver image obtained after the photothermographic imaging material was subjected to thermal development were measured, and the CIE 1976 (L ^* u ^* v ^* ) The coefficient of determination (multiple determination) R of the linear regression line created by arranging u ^* and v ^* at each of the above optical densities on two-dimensional coordinates where the horizontal axis of the color space is u ^* and the vertical axis is v ^{*. 2} is preferably 0.998 or more and 1.000 or less.

Further, the v ^* value at the intersection with the vertical axis of the linear regression line is −5 or more and 5 or less, and the slope (v ^* / u ^* ) is 0.7 or more and 2.5 or less. preferable.

(2) Further, each of the optical densities 0.5, 1.0, 1.5 and the minimum optical density of the imaging material was measured, and the horizontal axis of the CIE 1976 (L ^* a ^* b ^* ) color space was defined as a. ^* , The determination coefficient (double determination) R ^{2 of} the linear regression line created by arranging a ^* and b ^* at the above respective optical densities on two-dimensional coordinates with the vertical axis being b ^* is 0.998 or more and 1.000 or more. The following is preferred.

Furthermore, the b ^* value at the intersection with the vertical axis of the linear regression line is −5 or more and 5 or less, and the slope (b ^* / a ^* ) is 0.7 or more and 2.5 or less. preferable.

Next, an example of a method of creating the above-described linear regression line, that is, an example of a method of measuring u ^* , v ^* and a ^* , b ^{* in} the CIE 1976 color space will be described.

A four-stage wedge sample including an unexposed portion and optical densities of 0.5, 1.0, and 1.5 is prepared using a thermal developing apparatus. The wedge density parts thus produced are measured with a spectral colorimeter (eg, CM-3600d; manufactured by Minolta Co., Ltd.) to calculate u ^* , v ^* or a ^* , b ^* . The measurement is performed in a transmission measurement mode with an F7 light source as the 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 ^* plots to determine the coefficient determined the linear regression line (multiple determination) R ^2. Obtain the intercept and slope.

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

  In the present invention, the shape of the developed silver is adjusted by adjusting the addition amount of the following toning agent, developer, silver halide particles and compounds which are directly and indirectly involved in the development reaction process such as silver aliphatic carboxylate. It is possible to optimize and obtain a preferable color tone. For example, when the developed silver shape is a dendrite shape, the direction becomes bluish, and when the developed silver shape is a filament shape, the direction becomes yellowish. That is, the adjustment can be made in consideration of such a tendency of the developed silver shape.

  A preferred color tone can be obtained by adding a compound that generates a color dye by undergoing an oxidation-reduction reaction or a coupling reaction during development. The most preferred examples thereof are the combined use of the cyan-color-forming leuco dye of the present invention, the yellow-color-forming leuco dye and a reducing agent having a structure preferably used in the present invention.

(Other configuration requirements)
Next, each component of the silver salt photothermographic dry imaging material except for the items described above, and an image recording method and an image forming method using the same will be described.

  The photosensitive silver halide according to the present invention can be subjected to chemical sensitization. For example, use of a compound that releases a chalcogen such as sulfur, selenium, or tellurium, or a noble metal compound that releases a noble metal ion such as a gold ion by the methods described in JP-A-2001-249426 and JP-A-2001-249428. Thereby, a chemical sensitization center (chemical sensitization nucleus) can be formed and imparted. In particular, it is preferable that the sensitizer is chemically sensitized with an organic sensitizer containing a chalcogen atom.

  The organic sensitizer containing these chalcogen atoms is preferably a compound having a group capable of being adsorbed to silver halide and an unstable chalcogen atom site.

  These organic sensitizers have various structures disclosed in JP-A-60-150046, JP-A-4-109240, JP-A-11-218874, and U.S. Pat. No. 6,423,481. Organic sensitizers can be used, and among them, at least one compound having a structure in which a chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond is preferable.

The amount of a chalcogen compound added as an organic sensitizer kind of chalcogen compound to be used, silver halide grains will vary due reaction environment when subjected to chemical sensitization, per mol of silver halide, 1 × 10 ^{- It} is preferably from ⁸ to 1 × 10 ⁻² mol, more preferably from 1 × 10 ⁻⁷ to 1 × 10 ⁻³ mol.

  In addition to the above-described sensitization method, a reduction sensitization method and the like can also be used. Examples of shell-like compounds that can be used in the reduction sensitization method include ascorbic acid, thiourea dioxide, thiourea chloride and the like. 1 tin, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like can be used. Further, reduction sensitization can be performed by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less.

  In the present invention, the silver halide grains subjected to chemical sensitization may be formed in the presence of an organic silver salt, may be formed in the absence of an organic silver salt, or may be a mixture of both. It may be done.

  In the present invention, it is preferred that the surface of the photosensitive silver halide grains is subjected to chemical sensitization, and that the effect of the chemical sensitization substantially disappears after the heat development process. Here, the substantial disappearance of the chemical sensitization effect means that the sensitivity of the photosensitive material obtained by the above-described chemical sensitization technique is 1.1 times the sensitivity when the chemical sensitization is not performed after the heat development process. It means to decrease below.

  The photosensitive silver halide in the present invention is preferably subjected to spectral sensitization by absorbing a spectral sensitizing dye. Examples of the spectral sensitizing dye include a cyanine dye, a merocyanine dye, a complex cyanine dye, a complex merocyanine dye, a holopolar cyanine dye, a styryl dye, a hemicyanine dye, an oxonol dye, and a hemioxonol dye. 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. No. 4,639,414, The sensitizing dyes described in JP-A Nos. 4,740,455, 4,741,966, 4,751,175, and 4,835,096 can be used.

  Useful sensitizing dyes used in the present invention include, for example, Research Disclosure (hereinafter referred to as RD) No. 17643 IV-A (p.23, December 1978), RD No. 18431X (August 1978, p. 437). In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light source of various laser imagers and scanners, for example, JP-A-9-34078, JP-A-9-54409, and JP-A-9-80679. The compounds described in above are preferably used.

  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 dispersed in the form of fine particles, that is, in the form of a solid dispersion of silver halide grains or halogen. It can be added to a photosensitive emulsion containing silver halide grains / silver aliphatic carboxylate grains. Further, similarly to the heteroatom-containing compound having an adsorptive property to the silver halide grains, it is also possible to perform chemical sensitization 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. That is, the emulsion containing the photosensitive silver halide and the aliphatic carboxylic acid silver salt used in the silver salt photothermographic dry imaging material of the present invention is, together with the sensitizing dye, a dye having no spectral sensitizing action itself or a dye. A substance which does not substantially absorb visible light and exhibits a supersensitizing effect may be contained in the emulsion, whereby the silver halide grains may be supersensitized.

  Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in RD17643 (December, 1978), page 23, IV, J or JP-B No. 9-25500; JP-A-43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. As the supersensitizer, the following heteroaromatic sensitizers are used. Mercapto compounds or mercapto derivative compounds are preferred.

Ar-SM
In the formula, M is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or a condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. Preferably, the heteroaromatic ring is benzimidazole, naphthimidazole, benzthiazole, naphthothiazole, benzoxazole, naphthoxazole, benzselenazole, benztellurazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine , Purines, quinolines, or quinazolines. However, other heteroaromatic rings are also included.

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

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

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

  In addition to the above-described supersensitizer, a compound represented by the general formula [1] and a macrocyclic compound containing a hetero atom disclosed in Japanese Patent Application No. 2000-70296 can be used as the supersensitizer. .

  The supersensitizer according to the present invention is preferably used in the photosensitive layer containing an organic silver salt and silver halide grains in an amount of 0.001 to 1.0 mol per 1 mol of silver. Particularly preferably, the amount is 0.01 to 0.5 mol per mol of silver.

  In the present invention, it is preferable that the surface of the photosensitive silver halide grains is subjected to spectral sensitization by adsorbing a spectral sensitizing dye, and that the spectral sensitizing effect substantially disappears after a heat development process. . Here, the substantial disappearance of the spectral sensitizing effect means that the sensitivity of the imaging material obtained by the sensitizing dye, the supersensitizer or the like when the spectral sensitization is not performed after the heat development process. It means to decrease to 1.1 times or less.

  In the invention, the photosensitive layer or the non-photosensitive layer may contain a silver saving agent.

  The silver saving agent used in the present invention refers to a compound capable of reducing the amount of silver required for obtaining a constant silver image density. Although there are various possible mechanisms of the function of reducing the function, a compound having a function of improving the covering power of the developed silver is preferable. Here, the covering power of the developed silver means an optical density per unit amount of silver. The silver saving agent can be present in the photosensitive layer or the non-photosensitive layer, or both.

The amount of the silver saving agent is in the range of 1 × 10 ^-5 to 1 mol, preferably 1 × 10 ^{-4 to} 5 × 10 ^-1 mol, per 1 mol of the silver aliphatic carboxylate.

  In the present invention, a silane compound can also be preferably used as a kind of silver saving agent. In the present invention, the silane compound used as a silver saving agent is an alkoxysilane compound having two or more primary or secondary amino groups or a salt thereof as described in Japanese Patent Application No. 2001-192698. Is preferred. 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, the salt of the alkoxysilane compound means an adduct of an inorganic or organic acid and an alkoxysilane compound capable of forming an onium salt with an amino group.

  Suitable binders for the silver salt photothermographic dry imaging materials of the present invention are transparent or translucent, generally colorless, natural polymer synthetic resins and polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, Poly (vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid) ), Copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (ester) ) Poly (urethanes), phenoxy resins, poly (vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and polyamides. It may be hydrophilic or non-hydrophilic.

  A preferred binder for the photosensitive layer of the silver salt photothermographic dry imaging material of the present invention is polyvinyl acetal, and a particularly preferred binder is polyvinyl butyral. Details will be described later. In addition, for non-photosensitive layers such as an overcoat layer and an undercoat layer, particularly a protective layer and a back coat layer, polymers having a higher softening temperature, such as cellulose esters, particularly polymers such as triacetyl cellulose and cellulose acetate butyrate. Is preferred. If necessary, two or more of the above binders may be used in combination.

Such a binder is used in an effective range to function as a binder. Effective ranges can be readily determined by those skilled in the art. For example, as an index when at least the aliphatic carboxylic acid silver salt is retained in the photosensitive layer, the ratio of the binder to the aliphatic carboxylic acid silver salt is 15: 1 to 1: 2, particularly 8: 1 to 1: 1. Is preferable. That is, the binder amount of the photosensitive 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.

  As the binder used in the present invention, the heat transition temperature after development processing at a temperature of 100 ° C or higher is preferably 46 ° C or higher and 200 ° C or lower, more preferably 70 ° C or higher and 105 ° C or lower. is there. The thermal transition point temperature in the present invention is a value indicated by a VICAT softening point or a ring and ball method, and is a differential scanning calorimeter (DSC), for example, EXSTAR 6000 (manufactured by Seiko Instruments Inc.), DSC220C (manufactured by Seiko Instruments Inc.) ), DSC-7 (manufactured by PerkinElmer) or the like, and refers to an endothermic peak when a heat-developed photosensitive layer is isolated and measured. Generally, a high molecular compound has a glass transition point Tg. However, in a silver salt photothermographic dry imaging material, a large endothermic peak appears at a position lower than the Tg value of the binder resin used in the photosensitive layer. Appear. Focusing attention on this thermal transition temperature, as a result of intensive studies, it has been found that by setting this thermal transition temperature to 46 ° C. or more and 200 ° C. or less, not only the robustness of the formed coating film is increased, but also the sensitivity and the maximum Photographic performance such as density and image storability is greatly improved.

  The glass transition temperature (Tg) was determined by the method described in Brand Polymer, et al., “Polymer Handbook”, pages III-139 to III-179 (1966, Wiley & Sun). Tg in the case of a polymer 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 are each monomer in the copolymer Represents the Tg (° C.) of the homopolymer obtained from The accuracy of Tg calculated according to the above equation is ± 5 ° C.

  In the silver salt photothermographic dry imaging material of the present invention, as a binder contained in a photosensitive layer containing a silver salt of an aliphatic carboxylate, photosensitive silver halide particles, a reducing agent, and the like on a support, a conventionally known binder may be used. Molecular compounds can be used. It has a Tg of 70 to 105C, 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. Such examples include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylates, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic esters, styrene, butadiene, ethylene, vinyl butyral, vinyl acetal, There are compounds comprising a polymer or copolymer containing an ethylenically unsaturated monomer such as vinyl ether as a constitutional unit, a polyurethane resin, and 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. These polymer compounds are not particularly limited, and may be a homopolymer or a copolymer as long as the glass transition temperature (Tg) of the derived polymer is in the range of 70 to 105 ° C.

  Examples of the polymer or copolymer containing such an ethylenically unsaturated monomer as a constituent unit include alkyl acrylates, aryl acrylates, alkyl methacrylates, aryl methacrylates, alkyl cyanoacrylates. Esters, aryl cyanoacrylates, and the like, and the alkyl group and the aryl group thereof may or may not be substituted. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, amyl, hexyl, cyclohexyl, benzyl, chlorobenzyl, octyl, stearyl, sulfopropyl, N-ethyl-phenylaminoethyl, 2- (3-phenylpropyloxy) ethyl , Dimethylamino Phenoxyethyl, furfuryl, tetrahydrofurfuryl, phenyl, cresyl, naphthyl, 2-hydroxyethyl, 4-hydroxybutyl, triethylene glycol, dipropylene glycol, 2-methoxyethyl, 3-methoxybutyl, 2-acetoxyethyl, 2-acetate Acetoxyethyl, 2-ethoxyethyl, 2-iso-propoxyethyl, 2-butoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- (2-ethoxyethoxy) ethyl, 2- (2-butoxyethoxy) ethyl, Examples thereof include 2-diphenylphosphorylethyl, ω-methoxypolyethylene glycol (addition mole number n = 6), allyl, dimethylaminoethylmethyl chloride salt and the like.

  In addition, the following monomers can be used. Vinyl esters: Specific examples thereof include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxy acetate, vinyl phenyl acetate, vinyl benzoate, and vinyl salicylate. N-substituted acrylamides, N-substituted methacrylamides and acrylamide, methacrylamide: N-substituents include methyl, ethyl, propyl, butyl, t-butyl, cyclohexyl, benzyl, hydroxymethyl, methoxyethyl, dimethyl Aminoethyl, phenyl, dimethyl, diethyl, β-cyanoethyl, N- (2-acetoacetoxyethyl), diacetone, etc .; olefins: for example, dicyclopentadiene, ethylene, propylene, 1-butene 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene and the like; styrenes: for example, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, t-butyl styrene, chloro Methyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, methyl vinyl benzoate; vinyl ethers: for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy ethyl vinyl ether, dimethyl amino ethyl vinyl ether; N-substituted maleimides: methyl, ethyl, propyl, butyl, t-butyl, cyclohexyl, benzyl, n- Those having dodecyl, phenyl, 2-methylphenyl, 2,6-diethylphenyl, 2-chlorophenyl and the like; and others, butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate, diethyl maleate, maleate Dimethyl acid, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, glycidyl acrylate, glycidyl methacrylate, N-vinyl oxazolidone, N-vinyl pyrrolidone, acrylonitrile, Examples thereof include methacrylonitrile, methylenemalononitrile, and vinylidene chloride.

  Of 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. A polymer compound having an acetal group is excellent in compatibility with the aliphatic carboxylic acid to be generated, and therefore has a large effect of preventing the film from being softened, and thus is preferable.

  Further, a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and a relative humidity of 60% can be used as a binder within a range not to impair the effects of the present invention. More preferably, it is 0.01% by mass to 1.5% by mass, and still more preferably 0.02% by mass to 1% by mass. The definition and measurement method of the water content can be referred to, for example, Polymer Engineering Course 14, Polymer Material Testing Method (edited by the Society of Polymer Science, Jinjinshokan).

  In the present invention, it is preferable to use a cross-linking agent for the binder, thereby improving film attachment, reducing development unevenness, and suppressing fogging during storage and suppressing generation of printout silver after development. The effect is also obtained.

  Examples of the cross-linking agent used in the present invention include various cross-linking agents conventionally used for silver halide photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, and ethyleneimine described in JP-A-50-96216. , Vinyl sulfone, sulfonic acid ester, acryloyl, carbodiimide, and silane compound-based cross-linking agents can be used. Preferred are the following isocyanate-based compounds, silane compounds, epoxy compounds, and acid anhydrides.

  The amount of the crosslinking agent used in the present invention ranges from 0.001 to 2 mol, preferably from 0.005 to 0.5 mol, per mol of silver.

  The epoxy compound that can be used as a crosslinking agent may be any compound having at least one epoxy group, and there is no limitation on the number, molecular weight, and the like 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.

  An acid anhydride is a compound having at least one acid anhydride group represented by the following structural formula.

-CO-O-CO-
The acid anhydride only needs to have one or more such acid anhydride groups, and there is no limitation on the number, molecular weight, and the like of the acid anhydride groups.

These 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 some cases, chrome alum is also applicable.

  In the present invention, the acid anhydride can be added to any 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. Can be added to one or more layers. Further, it may be added to the same layer as the epoxy compound.

  In the silver salt photothermographic dry imaging material of the present invention, it is preferable that a toning agent for adjusting the color tone of silver is contained in a state usually dispersed in an (organic) binder matrix.

  Examples of suitable toning agents are disclosed in RD 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136 and 4,021,249. Have been. Particularly preferred toning agents are phthalazinone or a combination of phthalazine with phthalic acids and phthalic anhydrides.

  In the present invention, handling before development is carried out on the surface layer of the silver salt photothermographic dry imaging material (even when a non-photosensitive layer is provided on the photosensitive layer side or on the opposite side of the photosensitive layer with the support interposed therebetween). It is preferable to contain a matting agent in order to prevent damage to the image after heat and thermal development, and it is preferable to contain the matting agent in a mass ratio of 0.1 to 30% based on the binder. The material of the matting agent may be either an organic substance or an inorganic substance. For example, inorganic substances include silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, etc., and alkali described in British Patent No. 1,173,181 and the like. An earth metal or a carbonate such as cadmium or zinc can be used as a matting agent. Examples of organic substances include starch described in U.S. Pat. No. 2,322,037, starch derivatives described in Belgian Patent 625,451 and British Patent No. 981,198, and Japanese Patent Publication No. 44-3643. Polyvinyl alcohol, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, etc., polyacrylonitrile described in U.S. Pat. No. 3,079,257, and described in U.S. Pat. No. 3,022,169. An organic matting agent such as polycarbonate described above can be used.

  The matting agent preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. Further, a matting agent 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
In the present invention, the method of adding the matting agent may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed before the drying is completed after applying the coating solution. You may. When a plurality of types of matting agents are added, both methods may be used in combination.

  In the present invention, a conductive compound such as a metal oxide 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 an undercoat layer, a backing layer, a layer between the photosensitive layer and the undercoat, and the like. In the present invention, the conductive compounds described in U.S. Pat. No. 5,244,773, columns 14 to 20, are preferably used.

  Examples of the material of the support used for the silver salt photothermographic dry imaging material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, and metal (for example, aluminum). It is preferable that the material can be processed into a flexible sheet or roll. Accordingly, as the support in the silver salt photothermographic dry imaging 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 preferred, and 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.

  The silver salt photothermographic dry imaging material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. For example, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and on the opposite side of the support, for preventing sticking between photosensitive materials or in a photosensitive material roll. Preferably, a layer is provided. As a binder used for these protective layer and back coat layer, the glass transition point is higher than that of the heat-developable layer, abrasion, and a polymer that hardly deforms, for example, cellulose acetate, a polymer such as cellulose acetate butyrate, is a polymer of the binder. Selected from inside. In the present invention, it is preferable that the photosensitive layer is composed of two or more layers for the purpose of gradation adjustment or the like. For example, even if two or more photosensitive layers are provided on one side of the support, One or more layers may be provided on both sides.

  In the silver salt photothermographic dry imaging material of the present invention, in order to control the amount or wavelength distribution of light transmitted through the photosensitive layer, to form a filter layer on the same side or the opposite side to the photosensitive layer, Preferably, the layer contains a dye or pigment. As the dye to be used, known compounds that absorb light in various wavelength ranges according to the color sensitivity of the photosensitive material can be used. For example, when the silver salt photothermographic dry imaging material of the present invention is used as an image recording material using infrared light, it has a squarylium dye having a thiopyrylium nucleus and a pyrylium nucleus as disclosed in JP-A-2001-83655. It is preferred to use a squarylium dye, 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- in a molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Hereinafter, in the present specification, these dyes are collectively referred to as a squarylium dye for convenience. As the dye, a compound described in JP-A-8-201959 is also preferable.

  In the case where irradiation is prevented using a dye having absorption in the visible light region, it is preferable that the color of the dye does not substantially remain after image formation. And a basic precursor are preferably added to function as an antiirradiation layer. For these techniques, the methods described in JP-A-11-231457 and the like can be adopted.

  The silver salt photothermographic dry imaging material of the present invention is 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. Preferably. Here, the “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 coated on a support, coating and drying are repeated for each layer individually. Rather, it means that the respective constituent layers can be formed in a state where the steps of performing the multi-layer coating and drying at the same time 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, and for example, a known method such as a bar coater method, a curtain coat method, an immersion method, an air knife method, a hopper application method, and an extrusion application method. Can be used. Of these, a pre-metering type coating method called an extrusion coating method is more preferable. The extrusion coating method is suitable for precision coating and organic solvent coating because there is no volatilization on the slide surface unlike the slide coating method. This coating method has been described on the side having the photosensitive layer, but the same applies to the case where the backcoat layer is provided and the coating is performed together with the undercoating.

In the present invention, the silver coating amount is preferably 0.5 g / m ² or more and 1.5 g / m ² or less, and more preferably 1.0 g / m ² or more and 1.5 g / m ² or less.

  Further, in the above coated silver amount, those derived from silver halide preferably account for 2 to 18%, more preferably 3 to 15%, based on the total silver amount.

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 aliphatic carboxylic acid silver salt of the present invention is not less than 1 × 10 ⁻¹⁷ g and not more than 1 × 10 ⁻¹⁵ g per silver halide grain having a particle diameter of 0.01 μm or more (equivalent sphere equivalent diameter). Hereinafter, it is more preferably 1 × 10 ⁻¹⁶ g or more and 1 × 10 ⁻¹⁴ g or less.

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

  Next, the image recording method and the image forming method of the present invention will be described in detail.

  In the present invention, thermal development conditions vary depending on the equipment, apparatus, or method used, but typically involve heating the imagewise exposed silver halide photothermographic dry imaging material at an elevated temperature. . The latent image obtained after exposure can be obtained by heating the silver halide photothermographic dry imaging material at a moderately high temperature (eg, 80 to 200 ° C.) for a sufficient time (generally, about 1 second to about 2 minutes). Can be developed. If the heating temperature is lower than 80 ° C., a sufficient image density cannot be obtained in a short time, and 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 transportability, and to a developing machine. Also have an adverse effect. By heating, a silver image is generated by a redox reaction between a silver aliphatic carboxylate (which functions 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.

  As a device, an apparatus, and a means for heating, for example, a typical heating means such as a hot plate, an iron, a hot roller, and a heat generator using carbon or white titanium may be used. More preferably, the silver salt photothermographic dry imaging material provided with the protective layer, the surface of the side having the protective layer is brought into contact with a heating means, and heat treatment is performed. It is preferable from the viewpoint of properties and the like, and it is preferable that the surface is conveyed while being brought into contact with a heat roller, subjected to heat treatment, and developed.

  In the present invention, the silver salt photothermographic dry imaging material preferably contains a solvent in the range of 40 to 4500 ppm during development. More preferably, it is adjusted to be 100 to 500 ppm. This provides a silver salt photothermographic dry imaging material with high sensitivity, low fog, and high maximum density.

  Examples of the solvent include those described in paragraph [0030] of JP-A-2001-264930. However, it is not limited to these. These solvents can be used alone or in combination of several kinds.

  The content of the solvent in the photothermographic material can be adjusted by changing conditions such as 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.

  In the exposure of the silver salt photothermographic dry imaging material of the present invention, it is desirable to use an appropriate light source for the provided color sensitivity. For example, when a silver salt photothermographic dry imaging material is made to be able to feel infrared light, it can be applied to any light source in the infrared light range. An infrared semiconductor laser (780 nm, 820 nm) is more preferably used from the viewpoint that the photothermographic dry imaging material can be made transparent.

  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 vertical” means that the angle is closest to vertical during laser scanning, preferably 55 degrees or more and 88 degrees or less, more preferably 60 degrees or more and 86 degrees or less. Preferably, it is 65 degrees or more and 84 degrees or less, and most preferably 70 degrees or more and 82 degrees or less.

  The beam spot diameter on the exposed surface of the photosensitive material 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 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.

  Further, as a second method, it is preferable to perform exposure using a laser scanning exposure device 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 vertical single mode scanning laser beam.

  To achieve vertical multiplication, a method of using return light by multiplexing, or applying a high frequency superposition is preferable. In addition, 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.

In the image recording methods of the first and second embodiments, solid lasers such as ruby lasers, YAG lasers, glass lasers, and the like; HeNe lasers, Ar ions Gas lasers such as lasers, Kr ion lasers, CO ₂ lasers, CO lasers, HeCd lasers, N ₂ lasers, excimer lasers; InGaP lasers, AlGaAs lasers, GaAsP lasers, InGaAs lasers, InAsP lasers, CdSnP ₂ lasers, GaSb lasers, etc. A semiconductor laser; a chemical laser, a dye laser, or the like can be appropriately selected and used according to the application. Among them, a semiconductor laser having a wavelength of 600 to 1200 nm is preferably used from the viewpoint of maintenance and the size of a light source. In a laser used in a laser imager or a laser imagesetter, the beam spot diameter on the exposed surface when scanning a silver halide photothermographic dry imaging material is generally 5 to 75 μm as a short axis diameter and a long axis. The diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photosensitive material by the sensitivity at the laser oscillation wavelength and the laser power inherent to the silver salt photothermographic dry imaging material.

  Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1
<< Preparation of support >>
One side of a polyethylene terephthalate film base (thickness: 175 μm) colored blue with a concentration of 0.170 is subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , and the following undercoating solution is applied thereon A was used to coat the undercoat layer a so that the dry film thickness was 0.2 μm. Further, the other surface is similarly subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , and then the undercoating layer B is formed thereon by using the undercoating coating solution B described below. Was 0.1 μm. Thereafter, the support was prepared by performing a heat treatment at 130 ° C. for 15 minutes in a heat treatment oven having a film transport device including a plurality of roll groups.

(Preparation of Undercoat Coating Solution A)
270 g of a copolymer latex liquid (solid content 30%) of 30% by mass of n-butyl acrylate, 20% by mass of t-butyl acrylate, 25% by mass of styrene and 25% by mass of 2-hydroxyethyl acrylate, and a surfactant (UL-1) ) 0.6 g and methyl cellulose 0.5 g were mixed. Further, 1.3 g of silica particles (Syloid 350, manufactured by Fuji Silysia Ltd.) was added to 100 g of water, and dispersion treatment was performed for 30 minutes with an ultrasonic dispersing machine (ALEX Corporation, Ultrasonic Generator, frequency 25 kHz, 600 W). , And finally finished to 1000 ml with water to obtain an undercoating coating solution A.

(Preparation of Undercoat Coating Solution B)
37.5 g of the following colloidal tin oxide dispersion, 20% by mass of n-butyl acrylate, 30% by mass of t-butyl acrylate, 27% by mass of styrene and 28% by mass of 2-hydroxyethyl acrylate (solid content: 30% by mass) %) 3.7 g, n-butyl acrylate 40 mass%, styrene 20 mass%, glycidyl methacrylate 40 mass% copolymer latex liquid (solid content 30%), 14.8 g, and 0.1 g of surfactant (UL- 1) was mixed, and the mixture was made up to 1000 ml with water to obtain a subbing coating solution B.

<Preparation of colloidal tin oxide dispersion>
65 g of stannic chloride hydrate was dissolved in 2000 ml of a water / ethanol mixed solution to prepare a homogeneous solution. Then, it was boiled to obtain a coprecipitate. The generated precipitate was taken out by decantation and washed several times with distilled water. Silver nitrate is dropped into distilled water from which the precipitate has been washed, and after confirming that there is no reaction of chloride ions, distilled water is added to the washed precipitate to make the total volume 2000 ml. Further, 40 ml of 30% aqueous ammonia was added, and the aqueous solution was heated and concentrated until the volume became 470 ml to prepare a colloidal tin oxide dispersion.

<< Back side coating >>
While stirring 830 g of methyl ethyl ketone (hereinafter abbreviated as MEK), 84.2 g of cellulose acetate butyrate (Eastman Chemical, CAB381-20) and 4.5 g of polyester resin (Bostic, Vitel PE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved solution, and 4.5 g of a fluorine-based activator (Surflon KH40 manufactured by Asahi Glass Co., Ltd.) and 4 g of a fluorine-based activator (Dainippon) were dissolved in 43.2 g of methanol. 2.3 g of Megafag F120K (manufactured by Ink Corporation) was added, and the mixture was sufficiently stirred until dissolved. Finally, 75 g of silica (WR Grace, Syloid 64X6000) dispersed in MEK at a concentration of 1% by mass with a dissolver type homogenizer was added and stirred to prepare a coating solution for the back surface side.

  The coating solution for the back surface prepared in this manner was applied onto the undercoat layer (a) of the support prepared above by an extrusion coater so as to have a dry film thickness of 3.5 μm, and dried. 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.

<< Preparation of photosensitive silver halide emulsion >>
[Preparation of photosensitive silver halide emulsion 1]
(Solution A1)
88.3 g of phenylcarbamoylated gelatin
Compound A (* 1) (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finished to 5429 ml with water (Solution B1)
0.67mol / L silver nitrate aqueous solution 2635ml
(Solution C1)
Potassium bromide 51.55 g
1.47 g of potassium iodide
Finished to 660 ml with water (Solution D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
K ₃ OsCl ₆ + K ₄ [Fe (CN) ₆ ] (each dopant is equivalent to 2 × 10 ⁻⁵ mol / Ag) 50.0 ml
Finished to 1982 ml with water (Solution E1)
0.4 mol / L aqueous solution of potassium bromide The following silver potential control amount (solution F1)
Potassium hydroxide 0.71g
Finished to 20 ml with water (Solution G1)
56% acetic acid aqueous solution 18.0 ml
(Solution H1)
1.72 g of anhydrous sodium carbonate
(* 1) Compound A: HO (CH ₂ CH ₂ O) _n (CH (CH ₃ ) CH ₂ O) ₁₇ (CH ₂ CH ₂ O) _m H (m + n = 5 to 7)
Using a mixing stirrer described in JP-B-58-58288, a 1/4 amount of the solution B1 and a total amount of the solution C1 were added to the solution A1 at a temperature of 30 ° C. and a pAg of 8.09 by the simultaneous mixing method. Addition took 45 minutes to perform nucleation. One minute later, the entire amount of solution F1 was added. During this time, pAg was appropriately adjusted using the solution E1. After a lapse of 6 minutes, the temperature was raised to 40 ° C., and ３ of the solution B1 and the entire amount of the solution D1 were added over 14 minutes and 15 seconds by a double jet method while controlling the pAg at 8.09. After stirring for 5 minutes, the entire solution G1 was added, and the silver halide emulsion was precipitated. 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 except for the sedimented portion of 1500 ml, 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 mol of silver, to obtain an emulsion.

  This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 0.050 μm, a coefficient of variation in grain size of 12%, and a [100] face ratio of 92%.

<< Preparation of photosensitive layer coating solution >>
(Preparation of powdered aliphatic carboxylic acid 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 sodium fatty acid solution. After stirring for 20 minutes while maintaining the temperature of the fatty acid sodium solution at 55 ° C., 45.3 g (equivalent to 0.039 mol of silver) of the above photosensitive silver halide emulsion 1 and 450 ml of pure water were added, and the mixture was added for 5 minutes. Stirred.

  Next, 702.6 ml of a 1 mol / L silver nitrate solution was added over 2 minutes, and the mixture was stirred for 10 minutes to obtain a dispersion of silver aliphatic carboxylate. Thereafter, the obtained aliphatic carboxylic acid silver salt dispersion is transferred to a washing vessel, deionized water is added thereto, and the mixture is stirred and allowed to stand to allow the aliphatic carboxylic acid silver salt dispersion to float and separate. Was removed. After that, washing with deionized water and draining are repeated until the conductivity of the waste water reaches 50 μS / cm, and centrifugal dehydration is performed. The obtained cake-like aliphatic carboxylic acid silver salt is washed with a flash jet drier flash jet. Using a drier (manufactured by Seishin Enterprise Co., Ltd.), the powder was dried until the water content became 0.1% under the operating conditions of a nitrogen gas atmosphere and hot air temperature at the dryer entrance, to obtain powdered aliphatic carboxylic acid silver salt A. . An infrared moisture meter was used to measure the water content of the aliphatic carboxylic acid silver salt composition.

(Preparation of Preliminary Dispersion A)
14.57 g of polyvinyl butyral resin was dissolved in 1457 g of MEK, and 500 g of the powdered silver salt of aliphatic carboxylic acid A was gradually added while stirring with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN. A preliminary dispersion A was prepared by sufficiently mixing.

(Preparation of photosensitive emulsion dispersion A)
A media type in which the above-prepared preliminary dispersion liquid A is filled with zirconia beads having a diameter of 0.5 mm (Treseram, manufactured by Toray Industries Co., Ltd.) so that the residence time in the mill becomes 1.5 minutes using a pump. The emulsion was supplied to a disperser DISPERMAT SL-C12EX (manufactured by VMA-GETZMANN) and dispersed at a mill peripheral speed of 8 m / s to prepare a photosensitive emulsion dispersion A.

(Preparation of stabilizer liquid)
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, 1.488 g of 2-chloro-benzoic acid, 2.779 g of stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenzimidazole were added to 31.3 ml of MEK in the dark. Was dissolved at the same place to prepare an infrared sensitizing dye solution A.

(Preparation of additive liquid A)
Addition liquid A was prepared by dissolving 50 mg of the following thyuronium salt 1 in 5.0 g of methanol.

(Preparation of additive liquid B)
Addition liquid B was prepared by dissolving 1.0 g of sodium benzenethiosulfonate in 9.0 g of MEK.

(Preparation of additive liquid a)
27.98 g of the following developer 1, 0.7 g of the yellow chromogenic leuco dye 1 described below, 1.54 g of 4-methylphthalic acid, and 0.48 g of the infrared dye 1 were 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)
0.5 g of the following vinyl compound A was dissolved in 39.5 g of MEK to prepare an additive liquid c.

(Preparation of photosensitive layer coating solution A)
Under an inert gas atmosphere (nitrogen 97%), the photosensitive emulsion dispersion A (50 g) and 15.11 g of MEK were kept at 21 ° C. while stirring, and 390 μl of antifoggant 1 (10% methanol solution) was added. Stir for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added, and the mixture was stirred for 20 minutes. Subsequently, after adding 167 ml of the stabilizer solution and stirring for 10 minutes, 1.32 g of the infrared sensitizing dye solution A was added and stirred for 1 hour, and 6.4 g of the additive solution A, 0. 5 g of the additive liquid B was sequentially added, and immediately thereafter, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes. While keeping the temperature at 13 ° C., 13.31 g of butyral resin (Butvar) was added as a binder resin, and the mixture was stirred for 30 minutes. Then, 1.084 g of tetrachlorophthalic acid (9.4 mass% MEK solution) was added, and the mixture was added for 15 minutes. Stirred. 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 were added. By sequentially adding and stirring, a photosensitive layer coating solution A was obtained.

<< Preparation of coating solution for surface protective layer >>
While stirring 865 g of MEK, 96 g of cellulose acetate butyrate (Eastman Chemical Co., CAB171-15), 4.5 g of polymethyl methacrylic acid (Rohm & Haas Co., Paraloid A-21), and 1 g of vinyl sulfone compound (VSC) were added. 0.5 g, benzotriazole 1.0 g, and a fluorine-based activator (Asahi Glass Co., Ltd., Surflon KH40) 1.0 g were added and dissolved. Next, 30 g of the following matting agent dispersion was added and stirred to prepare a coating solution for the surface protective layer.

(Preparation of matting agent dispersion)
Cellulose acetate butyrate (Eastman Chemical Company, 7.5 g of CAB171-15) was dissolved in 42.5 g of MEK, and 5 g of calcium carbonate (Specialty Minerals, Super-Pflex200) was added thereto, followed by a dissolver-type homogenizer. The mixture was dispersed at 8000 rpm for 30 minutes to prepare a matting agent dispersion.

<< Preparation of silver salt photothermographic dry imaging material >>
(Preparation of Sample 101)
The sample 101 was prepared by simultaneously applying the prepared photosensitive layer coating solution A and the surface protective layer coating solution onto the undercoating layer b of the support using a known extrusion type coater. Produced. The coating was performed such that the photosensitive layer had a coated silver amount of 1.5 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm. Thereafter, drying was performed for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

(Preparation of Samples 102 to 115)
In the preparation of the sample 101, as shown below, the type of the photosensitive silver halide emulsion in the photosensitive layer coating solution A, the presence or absence of the tertiary alcohol when preparing the aliphatic silver carboxylate, and the cyan coloring leuco Samples 102 to 115 were prepared in the same manner except that the dyes were combined at different levels as shown in Table 1.

[Preparation of photosensitive silver halide emulsion 2]
In the preparation of photosensitive silver halide emulsion 1 described in Example 1, 3/4 amount of solution B1 and the entire amount of solution D1 were added over 14 minutes and 15 seconds by a double jet method while controlling the pAg to 8.09. A photosensitive silver halide emulsion 2 was prepared in exactly the same manner except that the temperature was changed to 27 ° C.

  This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 0.030 μm, a coefficient of variation in grain size of 14%, and a [100] face ratio of 90%.

[Preparation of photosensitive silver halide emulsion 3]
In the preparation of the above-mentioned photosensitive silver halide emulsion 1, the temperature was adjusted to 60 ° C. over 14 minutes and 15 seconds by the simultaneous mixing method while controlling the ３ amount of the solution B1 and the total amount of the solution D1 to pAg 8.09. A photosensitive silver halide emulsion 3 was prepared in exactly the same manner except that

  This emulsion was monodispersed cubic silver iodobromide grains having an average grain size of 0.080 μm, a grain size variation coefficient of 14%, and a [100] face ratio of 92%.

(Preparation of powdered aliphatic carboxylic acid silver salt in the presence of t-butyl alcohol)
In the preparation of the powdered silver aliphatic carboxylate A of Example 1, after obtaining the aliphatic sodium salt, 347 ml of t-butyl alcohol: t-BuOH was added while maintaining the temperature at 55 ° C., and the mixture was stirred for 20 minutes. A powdered aliphatic carboxylic acid silver salt prepared in the presence of t-butyl alcohol was prepared in exactly the same manner except that the photosensitive silver halide emulsion described in Table 1 was used.

(Preparation of powdered aliphatic carboxylic acid silver salt in the presence of 1,1-dimethyl-1-ethylmethanol)
In the preparation of the powdered silver salt of aliphatic carboxylic acid A of Example 1, after obtaining an aliphatic sodium salt, 545 ml of 1,1-dimethyl-1-ethylmethanol was added while keeping the temperature at 55 ° C. The mixture was stirred for 1 minute, and a silver salt of a powdered aliphatic carboxylic acid prepared in the presence of 1,1-dimethyl-1-ethylmethanol was prepared in exactly the same manner except that the emulsion was changed to the photosensitive silver halide emulsion shown in Table 1.

(Preparation of powdered aliphatic carboxylic acid silver salt in the presence of 1,1-dimethyl-1-phenylmethanol)
In the preparation of the powdered silver salt of aliphatic carboxylic acid A of Example 1, after obtaining the aliphatic sodium salt, 638 ml of 1,1-dimethyl-1-phenylmethanol was added while keeping the temperature at 55 ° C. The mixture was stirred for 1 minute, and a silver salt of a powdered aliphatic carboxylic acid prepared in the presence of 1,1-dimethyl-1-phenylmethanol was prepared in exactly the same manner except that the emulsion was changed to the photosensitive silver halide emulsion shown in Table 1.

(Preparation of Leuco Dye Additive Solution of the Present Invention)
In the preparation of the additive liquid a of Example 1, an additive liquid in which a cyan-color-forming leuco dye shown in Table 1 was additionally added, and the leuco dye was mixed and dissolved in the additive liquid a so as to be combined with the yellow-color-forming leuco dye. Was prepared, and the amount added to the coating solution was not changed. The amount of each leuco dye dissolved in the additive solution was all 0.07 g regardless of the type.

  In the sample 115, the type of the silver ion reducing agent was changed to the following developer 2 instead of the developer 1.

<< Exposure, development processing and evaluation of each characteristic value >>
(Exposure and development processing)
After each sample prepared as described above was stored at 25 ° C. and 50% RH (condition A) for 10 days, a vertical multi-mode with a wavelength of 800 to 820 nm was superimposed on the photosensitive layer coating side of each sample by high frequency superposition. Exposure by laser scanning was performed by an exposure machine using an integrated semiconductor laser (a single output having a maximum output of 35 mW combined into a maximum output of 70 mW) as an exposure source. At this time, an image was formed by setting the angle between the exposure surface of the sample and the exposure laser beam to 75 degrees. In this method, an image having less unevenness and unexpectedly good sharpness and the like was obtained as compared with the case where the angle was set to 90 degrees.

  Then, using an automatic developing machine having a heat drum, the surface protective layer of the sample was brought into contact with the surface of the heat drum to carry out heat development at 125 ° C. for 15 seconds, and then 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. The above exposure and development were performed in a room conditioned at 23 ° C. and 50% RH.

(Measurement of sensitivity and fog density)
The density of each formed image obtained as described above was measured using a densitometer, and a characteristic curve consisting of the horizontal axis-exposure amount and the vertical axis-density was created. In the characteristic curve, the relative sensitivity was defined as the reciprocal of the exposure amount giving a density 1.0 higher than that of the unexposed portion, and the fog density (minimum density) and the maximum density were measured. The relative sensitivity was represented by a relative value with the sensitivity of the sample 101 being 100.

(Measurement of u ^* and v ^* in CIE 1976 color space)
(R ² value condition A)
Each sample stored at 23 ° C. and 50% RH (condition A) for 10 days was subjected to a four-stage process including an unexposed portion and an optical density of 0.5, 1.0, and 1.5 using the above-described thermal developing apparatus. A developed wedge sample was prepared. The wedge density parts thus produced were measured with CM-3600d (manufactured by Minolta Co., Ltd.) to calculate u ^* and v ^* . 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 ^*, the vertical axis v u ^* measured in ^* and the on the graph, and a multiple determination R ² value condition A search of plot linear regression line of v ^*. This value is a value indicating the degree of change in color tone at each density, and the closer to 1.0, the smaller the change in color tone at each density.

(R ² value condition B)
The developed sample prepared under the above-mentioned R ² value condition A was placed in a 45 ° C., 55% RH environment using a commercially available white fluorescent lamp such that the illuminance on the surface of the photosensitive layer side was 9000 lux, for 3 days. After the continuous irradiation, a linear regression line was obtained in exactly the same manner as in the above-mentioned R ² value condition A, and was used as a double-determined R ² value condition B. This evaluation is a quantitative value indicating the degree of color tone change at each density after the image is stored.

(Average R ² value)
In the above-described method for determining the R ² value condition A, 100 identical exposures and developments were successively performed continuously, 100 developed samples of each density were prepared, and the average value of the obtained R ² values was determined. ^Two values. This is to determine the reproducibility of the R ² value for each development.

(Evaluation of image density unevenness resistance)
After leaving each sample for 10 days under the above-mentioned condition A, developing it by the same method as the above-mentioned sensitivity and fog measurement, the obtained image was visually evaluated, and the image density unevenness resistance was evaluated according to the following criteria. went.

A: No image unevenness is recognized at all. B: Slight image unevenness is recognized when staring, but within a practically acceptable range. C: Clear image unevenness is recognized, and the quality poses a problem in practical use.

  Table 2 shows the results obtained as described above.

  As is evident from the results in Table 2, the photosensitive silver halide grains are only formed as non-photosensitive aliphatic silver carboxylate grains in the present invention in the particle size ratio or in the presence of a tertiary alcohol. Although the maximum density increases, the color tone deteriorates.

On the other hand, when the cyan-color-forming leuco dye of the present invention is used in combination, any of the R ² values becomes close to 1.00, and the color tone can be improved to a preferable one.

  This shows that at each density, the color tone was improved to a desirable one, and that the image storability after development and the reproducibility for each processing were also very excellent.

  Even more surprisingly, the samples of the present invention have improved density unevenness after development. Although the reason for this is not clear, visual observation involves not only the density unevenness in the same hue but also the subtle hue effect, and the hue change effect in each density is extremely large due to the color tone improvement effect of the present invention. Probably because it became smaller.

Example 2
<< Preparation of polyethylene terephthalate support >>
Polyethylene terephthalate (hereinafter abbreviated as PET) having an intrinsic viscosity IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) using terephthalic acid and ethylene glycol according to a conventional method. ) Got. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and quenched to prepare an unstretched film having a thickness of 175 μm after heat setting.

This unstretched PET film was longitudinally stretched 3.3 times using rolls having different peripheral speeds, and then horizontally stretched 4.5 times using a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, after heat-setting at 240 ° C. for 20 seconds, it was relaxed by 4% in the lateral direction at the same temperature. After slitting the chuck portion of the tenter, knurling was performed on both ends, and the tenter was wound at 40 N / cm ² to obtain a roll-shaped support having a thickness of 175 μm.

<Surface corona treatment of support>
Using a solid state corona treatment machine 6KVA model manufactured by Pillar Co., both surfaces of the support were treated at room temperature at 20 m / min. From the current and voltage readings at this time, it was found that the support was treated at 0.375 kV · A · min / m ² . The processing frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

<Preparation of undercoated support>
(Preparation of undercoat layer coating solution)
(Coating solution for the undercoat layer on the image forming side)
234 g of Pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5, 10% by mass solution) 21.5 g
0.91 g of polymer fine particles (manufactured by Soken Chemical Co., Ltd., MP-1000, average particle size 0.4 μm)
935 ml of distilled water
(Coating solution for the first layer of the undercoat layer on the back side)
158 g of styrene-butadiene copolymer latex (solid content 40% by mass, styrene / butadiene mass ratio = 68/32)
2,4-Dichloro-6-hydroxy-S-triazine sodium salt (8% by mass aqueous solution) 20 g
Sodium laurylbenzenesulfonate (1% by mass aqueous solution) 10ml
854 ml of distilled water
(Coating solution for the second layer of the undercoat layer on the back side)
84 g of SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion)
Gelatin (10% by mass aqueous solution) 89.2 g
8.6 g of Metroose TC-5 (2% by mass aqueous solution) manufactured by Shin-Etsu Chemical Co., Ltd.
Soken Chemical Co., Ltd., MP-1000 0.01g
Sodium dodecylbenzenesulfonate (1% by mass aqueous solution) 10ml
6 ml of NaOH (1% by mass)
Proxel (ICI) 1ml
805 ml of distilled water
After applying the corona discharge treatment to both surfaces of the biaxially stretched PET support having a thickness of 175 μm, the coating liquid for the undercoat layer on the image forming surface side is wet-coated with a wire bar on the image forming layer surface side. Of 6.6 ml / m ² (per side) and dried at 180 ° C. for 5 minutes. Then, on the back side (back side), apply the coating liquid for the first layer of the back side undercoat layer to a wire. The coating is performed with a bar so that the wet coating amount is 5.7 ml / m ² , dried at 180 ° C. for 5 minutes, and further coated on the back surface (back surface) with the back surface side undercoat layer second layer coating solution. Was applied so that the wet coating amount was 7.7 ml / m ² , and dried at 180 ° C. for 6 minutes to produce a subbed support.

<< Preparation of back side coating solution >>
(Preparation of solid fine particle dispersion (a) of base precursor)
64 g of the base precursor compound 1, 28 g of diphenyl sulfone, and 10 g of the surfactant Demol N manufactured by Kao Corporation were mixed with 220 ml of distilled water, and the mixture was sand-milled (1.14 L sand grinder mill, manufactured by IMEX Co., Ltd.). The resulting mixture was dispersed in beads to obtain a solid fine particle dispersion (a) of a base precursor compound having an average particle diameter of 0.2 μm.

(Preparation of solid dye fine particle dispersion)
9.6 g of cyanine dye compound 1 and 5.8 g of sodium p-dodecylbenzenesulfonate were mixed with 305 ml of distilled water, and the mixed solution was dispersed in beads using a sand mill (1.14 L sand grinder mill, manufactured by Imex Co., Ltd.). As a result, a dye solid fine particle dispersion having an average particle size of 0.2 μm was obtained.

(Preparation of antihalation layer coating solution)
17 g of gelatin, 9.6 g of polyacrylamide, 56 g of the solid fine particle dispersion (a) of the above-mentioned base precursor, 50 g of the above solid fine particle dispersion of the dye, and monodispersed polymethyl methacrylate fine particles (average particle size 8.0 μm, particle size standard deviation 0. 4) 1.5 g, benzoisothiazolinone 0.03 g, sodium polyethylenesulfonate 2.2 g, blue dye compound 1 0.1 g, and 844 ml of water were mixed to prepare an antihalation layer coating solution.

(Preparation of back surface protective layer coating solution)
The container was kept warm at 40 ° C., gelatin 50 g, polystyrene sodium sulfonate 0.2 g, N, N-ethylenebis (vinylsulfone acetamide) 2.4 g, sodium t-octylphenoxyethoxyethaneethanesulfonate 1 g, benzoisothiazolinone 30 mg 37 mg of fluorine-based surfactant (F-1), 150 mg of fluorine-based surfactant (F-2), 64 mg of fluorine-based surfactant (F-3), fluorine-based surfactant (F-4) 32 mg, acrylic acid / ethyl acrylate copolymer (copolymerization mass ratio 5/95) 8.8 g, aerosol OT (manufactured by American Cyanamid Co.) 0.6 g, liquid paraffin emulsion 1.8 g as liquid paraffin, 950 ml of water was mixed to prepare a back surface protective layer coating solution.

_{F-1: C 8 F 17} SO 2 N (n-C 3 H 7) CH 2 COOK
_{F-2: C 8 F 17} SO 2 N (n-C 3 H 7) CH 2 CH 2 O- (CH 2 CH 2 O) n-H
_{F-3: C 8 F 17} SO 2 N (n-C 3 H 7) (CH 2 CH 2 O) 4 CH 2 CH 2 CH 2 CH 2 SO 3 Na
F-4: C ₈ F ₁₇ SO ₂ K
<< Preparation of the coating solution on the image forming side >>
<< Preparation of photosensitive silver halide emulsion >>
[Preparation of photosensitive silver halide emulsion 4]
The photosensitive silver halide emulsion 1 prepared in Example 1 was maintained at 38 ° C. while stirring, and 5 ml of a 0.34 mass% 1,2-benzoisothiazolin-3-one methanol solution was added. A solution of sensitizing dye D-1 in methanol was added at 1.2 × 10 ⁻³ mol per mol of silver, and the temperature was raised to 47 ° C. one minute later. Twenty minutes after the temperature was raised, 7.6 × 10 ⁻⁵ mol of sodium benzenethiosulfonate was added to 1 mol of silver in a methanol solution, and further 5 minutes later, tellurium sensitizer C was added in an amount of 2.75 mol per mol of silver in a methanol solution. 9 × 10 ^-4 mol was added and the mixture was aged for 91 minutes. Thereafter, 1.3 ml of a 0.8% by mass methanol solution of N, N′-dihydroxy-N ″ -diethylmelamine was added to prepare a photosensitive silver halide emulsion 4.

[Preparation of photosensitive silver halide emulsion 5]
In the preparation of the photosensitive silver halide emulsion 4 described above, the silver halide emulsion to be sensitized was changed to the photosensitive silver halide emulsion 2 prepared in Example 1, and the methanol solution of the sensitizing dye D-1 was changed to silver. Except that the amount of addition of the tellurium sensitizer C was changed to 6.0 × 10 ^-3 mol per mol and 5.2 × 10 ^-4 mol per mol of silver, the same manner as in the photosensitive silver halide emulsion 4 was used. Thus, photosensitive silver halide emulsion 5 was obtained.

[Preparation of photosensitive silver halide emulsion 6]
In the preparation of the photosensitive silver halide emulsion 4 described above, the silver halide emulsion to be sensitized was changed to the photosensitive silver halide emulsion 3 prepared in Example 1, and the methanol solution of the sensitizing dye D-1 was changed to silver. Except that the amount of 7.5 × 10 ⁻³ mol per mol and the amount of tellurium sensitizer C were changed to 1.1 × 10 ⁻⁴ mol per mol of silver, the same as in the case of the photosensitive silver halide emulsion 4, was used. Thus, photosensitive silver halide emulsion 6 was obtained.

(Preparation of mixed emulsion for coating solution)
The photosensitive silver halide emulsions 4 to 6 prepared above were combined as shown in Table 3, and a 1% by mass aqueous solution of benzothiazolium iodide was added in an amount of 7 × 10 ⁻³ mol per mol of silver. Further, water was added so that the silver halide content per kg of the mixed emulsion for coating was 38.2 g as silver.

<< Preparation of each additive >>
(Preparation of fatty acid silver dispersion 1)
A mixture of 87.6 kg of behenic acid manufactured by Henkel (product name Edenor C22-85R), 423 L of distilled water, 49.2 L of a 5 mol / L aqueous solution of NaOH, and 120 L of t-butyl alcohol were mixed together. The reaction was carried out by stirring at 1 ° C. for 1 hour to obtain a sodium behenate solution. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept at 10 ° C. The reaction vessel filled with 665 L of distilled water was kept at 30 ° C., and with sufficient stirring, the total amount of the sodium behenate solution and the total amount of the silver nitrate aqueous solution were supplied at constant flow rates over 93 minutes, 15 seconds and 90 minutes, respectively. Was added. At this time, only the aqueous solution of silver nitrate was added for 11 minutes after the addition of the aqueous solution of silver nitrate was started, and then the addition of the sodium behenate solution was started. It was made to be added. At this time, the temperature inside the reaction vessel was set at 30 ° C., and the external temperature was controlled so that the liquid temperature became constant. Also, the piping of the addition system of the sodium behenate solution was kept warm by circulating hot water outside the double pipe, and the liquid temperature at the outlet of the tip of the addition nozzle was adjusted to 75 ° C. The piping of the silver nitrate aqueous solution addition system was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution and the addition position of the aqueous silver nitrate solution were arranged symmetrically with respect to the stirring axis, and were adjusted to a height such that they did not come into contact with the reaction solution.

  After the addition of the sodium behenate solution was completed, the mixture was left to stir at the same temperature for 20 minutes, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of the ripening, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of the filtered water became 30 μS / cm, to obtain a fatty acid silver salt. The obtained solid was stored as a wet cake without drying.

  The morphology of the obtained silver behenate particles was evaluated by electron microscopic photographing. The average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, and average sphere equivalent diameter. It was a scaly crystal having a sphere equivalent diameter of 0.52 μm and a coefficient of variation of 15%. When the shape of the silver salt of an organic acid is approximated to a rectangular parallelepiped, the coefficients a, b, and c are set to a, b, and c from the shortest side of the rectangular parallelepiped.

  To a wet cake having a dry solid content of 260 kg, 19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to make the total amount 1000 kg, and then the slurry is slurried with dissolver blades. Further, a pipeline mixer (Mizuho Industry Co., Ltd.) Pre-dispersed by the trade name PM-10 (trade name).

  Next, the predispersed undiluted solution was treated three times by adjusting the pressure of a dispersing machine (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) to 124 MPa. Thus, a fatty acid silver dispersion 1 was obtained.

(Preparation of fatty acid silver dispersion 2)
A fatty acid silver dispersion 2 was prepared in exactly the same manner as in the preparation of the fatty acid silver dispersion 1, except that 665 L of distilled water was changed to 635 L of distilled water and 30 L of t-butyl alcohol.

(Preparation of Dispersion of Reducing Agent Complex-1)
10 kg of a 1: 1 complex of the developer 1 and triphenylphosphine oxide used in Example 1, 0.12 kg of triphenylphosphine oxide and 16 kg of a 10% by mass aqueous solution of modified polyvinyl alcohol (Poval MP203, manufactured by Kuraray Co., Ltd.) , 10 kg of water was added thereto and mixed well to form a slurry. This slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 4 hours and 30 minutes, and then benzoisothiazolinone sodium salt was added. 0.2 g and water were added to adjust the concentration of the reducing agent to 22% by mass to obtain a reducing agent complex-1 dispersion. The thus obtained reducing agent complex-1 particles had a median diameter of 0.45 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent complex-1 dispersion was filtered with a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust.

(Preparation of Development Accelerator-1 Dispersion)
10 kg of the development accelerator-1 and 20 kg of a 10% by mass aqueous solution of a modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., Poval MP203) were added to 10 kg of water and mixed well to form a slurry. The slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 3 hours and 30 minutes, and then benzoisothiazolinone sodium salt was used. By adding 0.2 g and water, the concentration of the reducing agent was adjusted to be 20% by mass to obtain a development accelerator-1 dispersion. The thus obtained development accelerator-1 particles had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The resulting development accelerator-1 dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust.

  A 20% by mass dispersion of a yellow leuco dye having the following structure was prepared in the same manner as the development accelerator-1 dispersion described above.

<Preparation of mercapto compound>
(Preparation of Mercapto Compound-1 Aqueous Solution)
Mercapto compound-1: 7 g of (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.

(Preparation of mercapto compound-2 aqueous solution)
Mercapto compound-2: 20 g of (1- (3-methylureido) -5-mercaptotetrazole sodium salt) was dissolved in 980 g of water to prepare a 2.0% by mass aqueous solution.

<Preparation of polyhalogen compound>
(Preparation of Dispersion of Organic Polyhalogen Compound-1)
Organic polyhalogen compound-1: 10 kg of (tribromomethanesulfonylbenzene), 10 kg of a 20% aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20% aqueous solution of sodium triisopropylnaphthalenesulfonate Was added to 14 kg of water and mixed well to form a slurry. The slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by IMEX Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then sodium benzoisothiazolinone sodium salt was added. 2 g and water were added to adjust the concentration of the organic polyhalogen compound to 26% by mass to obtain an organic polyhalogen compound-1 dispersion. The thus-obtained organic polyhalogen compound-1 particles had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound-1 dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust.

(Preparation of organic polyhalogen compound-2 dispersion)
Organic polyhalogen compound-2: 10 kg of (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by mass aqueous solution of a modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and triisopropylnaphthalene sulfone 0.4 kg of a 20% by mass aqueous solution of sodium acid was mixed well to form a slurry. The slurry was sent by a diaphragm pump and dispersed in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm for 5 hours, and then benzoisothiazolinone sodium salt 0 was added. 0.2 g and water were added to adjust the concentration of the organic polyhalogen compound to 30% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-2 dispersion. The thus-obtained organic polyhalogen compound-2 particles had a median diameter of 0.40 μm and a maximum particle diameter of 1.3 μm or less. The resulting organic polyhalogen compound-2 dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust.

(Preparation of phthalazine compound-1 solution)
8 kg of modified polyvinyl alcohol MP203 manufactured by Kuraray Co., Ltd. is dissolved in 174.57 kg of water, then 3.15 kg of a 20% by mass aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1: (6-isopropylphthalazine) Was added to prepare a 5% by mass solution of phthalazine compound-1.

(Preparation of Pigment-1 Dispersion)
C. I. Pigment Blue 60 and 6.4 g of Demol N manufactured by Kao Corporation were added to 250 g of water and mixed to form a slurry. 800 g of zirconia beads having an average diameter of 0.5 mm is prepared, put into a vessel together with the slurry, and dispersed with a dispersing machine (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 25 hours to obtain a pigment-1 dispersion. Obtained. The average particle size of the pigment-1 particles contained in the pigment dispersion thus obtained was 0.21 μm.

<Preparation of emulsion layer coating solution>
1000 g of the fatty acid silver dispersion obtained above, 276 ml of water, 33.2 g of pigment-1 dispersion, 21 g of organic polyhalogen compound-1 dispersion, 58 g of organic polyhalogen compound-2 dispersion, 58 g of phthalazine compound- 173 g of 1 solution, 2380 g of 20 mass% gelatin solution, 299 g of dispersion of reducing agent complex-1, 6 g of dispersion of development accelerator-1, 2 g of dispersion of yellow leuco dye, 9 ml of aqueous solution of mercapto compound-1 and mercapto compound- 27 ml of an aqueous solution 2 were added in sequence, and 117 g of a silver halide mixed emulsion (described as a silver mass ratio in Table 3) was added immediately before coating, and mixed well to prepare an emulsion layer coating solution-1. The solution was sent to the coating die as it was and applied.

  The viscosity of the emulsion layer coating solution was 25 mPa · s at 40 ° C. (No. 1 rotor, 60 rpm) as measured by a B-type viscometer of Tokyo Keiki. The viscosity of the coating solution at 25 ° C. using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd. was 230, 60, and 46 at a shear rate of 0.1, 1, 10, 100, and 1000 (1 / second), respectively. , 24 and 18 mPa · s. The amount of zirconium in the coating solution was 0.38 mg / g of silver.

<Preparation of coating solution for intermediate layer>
1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 272 g of a 5% by mass dispersion of a pigment, and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio 64/9) / 20/5/2) To 4200 ml of a 19% by mass latex solution, 27 ml of a 5% by mass aqueous solution of aerosol OT (manufactured by American Cyanamid) and 135 ml of a 20% by mass aqueous solution of diammonium phthalate were added. Water was added so that the total amount became 10000 g, and the mixture was adjusted with NaOH so that the pH became 7.5 to obtain an intermediate layer coating solution, which was then sent to a coating die so as to have a pH of 9.1 ml / m ² . The viscosity of the coating solution was 58 mPa · s.

<Preparation of coating liquid for first protective layer>
64 g of inert gelatin was dissolved in water, and 80 g of a 27.5% by mass liquid of a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio of 64/9/20/5/2) latex was obtained. 23 ml of 10% by mass methanol solution of phthalic acid, 23 ml of 10% by mass aqueous solution of 4-methylphthalic acid, 28 ml of 0.5 mol / L sulfuric acid, 5% by mass aqueous solution of Aerosol OT (American Cyanamid) 5 ml, phenoxyethanol 0.5 g and benzoisothiazolinone 0.1 g, water was added to make a total amount of 750 g to make a coating solution, and 26 ml of 4% by mass chrome alum was mixed with a static mixer immediately before coating. Was sent to the coating die at 18.6 ml / m ² . The viscosity of the coating solution was 20 mPa · s.

<Preparation of coating liquid for protective layer second layer>
80 g of inert gelatin was dissolved in water, and 102 g of a 27.5% by mass liquid of methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymer mass ratio: 64/9/20/5/2) latex, 3.2 ml of a 5% by weight solution of a fluorine-based surfactant (potassium N-perfluorooctylsulfonyl-N-propylalanine salt) was added to a fluorine-based surfactant (polyethylene glycol mono (N-perfluorooctylsulfonyl-N-propyl). 32 ml of a 2% by weight aqueous solution of 2-aminoethyl) ether [average degree of polymerization of ethylene oxide = 15]), 23 ml of a 5% by weight solution of aerosol OT (manufactured by American Cyanamid Co., Ltd.), polymethyl methacrylate fine particles (average particles) Diameter 0.7μm) 4g, polymethylmethac 21 g of fine particles (average particle size: 4.5 μm), 1.6 g of 4-methylphthalic acid, 4.8 g of phthalic acid, 44 ml of sulfuric acid having a concentration of 0.5 mol / L, and 10 mg of benzoisothiazolinone were mixed with water to make a total amount of 650 g. Immediately before coating, 445 ml of an aqueous solution containing 4% by mass of chromium alum and 0.67% by mass of phthalic acid were mixed with a static mixer to obtain a coating solution for the surface protective layer, which was adjusted to 8.3 ml / m ² . The solution was sent to the coating die. The viscosity of the coating solution was 19 mPa · s.

<< Preparation of silver salt photothermographic dry imaging material >>
(Preparation of sample 201)
On the back surface side of the undercoating support, the antihalation layer coating solution is coated so that the solid content of the solid fine particle dye is 0.04 g / m ^2, and the back surface protection layer coating solution is coated with gelatin. Coating was performed simultaneously at 1.7 g / m ² to form a back layer.

On the surface opposite to the back surface, from the undercoat surface, the emulsion layer coating solution, the intermediate layer coating solution, the protective layer first layer coating solution, and the protective layer second layer coating solution, in the order of the slide bead coating method, and simultaneously multi-layer coating, Sample 201 which is a silver salt photothermographic dry imaging material was produced. At this time, the temperature of the emulsion layer and the intermediate layer was adjusted to 31 ° C., the temperature of the first protective layer was adjusted to 36 ° C., and the temperature of the second protective layer was adjusted to 37 ° C. The coating amount (g / m ² ) of each compound in the emulsion layer is as follows.

5.55 silver behenate
Pigment (CI Pigment Blue 60) 0.036
Polyhalogen compound-1 0.12
Polyhalogen compound-2 0.37
Phthalazine compound-1 0.19
Gelatin 9.97
Reducing agent complex-1 1.41
Development accelerator-1 0.024
Yellow leuco dye 0.010
Mercapto compound-1 0.002
Mercapto compound-2 0.012
Silver halide (as Ag) 0.091
The coating and drying conditions are as follows. The coating was performed at a speed of 160 m / min, the gap between the tip of the coating die and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with ion wind before coating. In the subsequent chilling zone, the coating liquid is cooled by air having a dry-bulb temperature of 10 to 20 ° C., and is then transferred in a non-contact type. It was dried with a dry air having a wet bulb temperature of 15 to 21 ° C. After drying, the film was conditioned at 25 ° C. and a humidity of 40 to 60% RH, and then the film surface was heated to 70 to 90 ° C. After heating, the film surface was cooled to 25 ° C.

  The matte degree of the produced photothermographic material was 550 seconds on the image forming layer side and 130 seconds on the back side in Beck smoothness. Further, the pH of the film surface on the side of the image forming layer was measured and found to be 6.0.

(Preparation of Samples 202 to 214)
Table 3 shows the type of binder, the type of cyan leuco dye, the type and ratio of the photosensitive silver halide emulsion, and the non-photosensitive silver carboxylate used in the photosensitive layer used in the emulsion layer coating solution of Sample 101. Samples 202 to 214 were prepared in the same manner except that the combination described in (1) was used. However, the cyan leuco dye of the present invention was prepared in the same manner as the development accelerator and the yellow leuco dye, and a dispersion of 20% by mass was prepared and added to the coating liquid, and the coating amount was 0.010 g / m ² .

(Preparation of Cyanogenic Leuco Dye Dispersion of the Present Invention)
In the same manner as the development accelerator-1 dispersion described above, a 20% by mass dispersion of each cyan leuco dye of the present invention shown in Table 3 was prepared.

(Binder used for photosensitive layer)
As shown in Table 3, the binder used for each sample was prepared as follows.

  Incidentally, PVA-217 manufactured by Kuraray Co., Ltd. was used. Hereinafter, a method for preparing latexes 1 to 3 will be described.

<Preparation of latex liquid>
Latex with Tg = 22 ° C. (* Latex 1) was prepared according to the following method. Using ammonium persulfate as a polymerization initiator and an anionic surfactant as an emulsifier, 70.0% by mass of styrene, 27.0% by mass of butadiene, and 3.0% by mass of acrylic acid were emulsion-polymerized, and then 8 ° C. at 80 ° C. Time aging was performed. Thereafter, the mixture was cooled to 40 ° C., adjusted to pH 7.0 with ammonia water, and further added with Sandet BL manufactured by Sanyo Chemical Co., Ltd. to a concentration of 0.22%. Next, the pH was adjusted to 8.3 by adding a 5% aqueous sodium hydroxide solution, and further adjusted to 8.4 with ammonia water. The molar ratio of Na ⁺ ion to NH ₄ ⁺ ion used at this time was 1: 2.3. Further, 0.15 ml of a 7% aqueous solution of sodium salt of benzoisothiazolinone was added to 1 kg of this liquid to prepare a latex liquid 1.

* Latex 1: Latex of styrene (70.0) / butadiene (27.0) / acrylic acid (3.0) The latex 1 prepared above had a Tg of 22 ° C, an average particle size of 0.1 µm, and a concentration of 43. Mass%, equilibrium water content at 25 ° C. 60% RH: 0.6 mass%, ionic conductivity: 4.2 mS / cm (Ion conductivity is measured using a conductivity meter CM-30S manufactured by Toa Denpa Kogyo Co., Ltd.) The latex stock solution (43% by mass) was measured at 25 ° C.), and the pH was 8.4. Latexes having different Tg can be prepared by a similar method by appropriately changing the ratio and type of styrene and butadiene.

* Latex 2: Latex of styrene (68.0) / butadiene (30.0) / acrylic acid (2.0). In addition, Tg was 20 ° C.
* Latex 3: Latex of styrene (75.0) / butadiene (15.0) / methyl methacrylate (10.0). In addition, Tg was 31 ° C.

  In the sample 214, the developer 1 was changed to the same amount of the following developer 3.

  Each sample was evaluated in exactly the same manner as in Example 1.

  Table 4 shows the obtained results.

  As is clear from the results in Table 4, a high maximum density can be obtained only by changing the binder of the photosensitive layer to the binder of the present invention, but the color tone deteriorates.

  When the cyan-chromogenic leuco dye of the present invention is used in combination, the color tone is improved without impairing the high maximum density.

  Further combination of the combination of the particle size of the photosensitive silver halide particles of the present invention and the formation of the non-photosensitive silver aliphatic carboxylate particles in the presence of a tertiary alcohol provides a more preferable color tone, It can be seen that the reproducibility is also high.

Claims (8)

Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material The photosensitive silver halide particles containing a cyan-chromogenic leuco dye, wherein the ratio of the photosensitive silver halide particles having an average particle diameter of 0.01 μm or more and 0.04 μm or less is the total photosensitive halogen in terms of silver amount. A silver salt photothermographic dry imaging material, characterized in that the content is 5% by mass or more and 50% by mass or less of silver halide particles. Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material A silver ion-containing solution containing a cyan coloring leuco dye, wherein the non-photosensitive aliphatic carboxylic acid silver salt particles are water or a mixture of water and an organic solvent as a solvent in the presence of a tertiary alcohol; A silver salt photothermographic dry imaging material produced by reacting a solution containing an alkali metal salt of an aliphatic carboxylic acid with an organic solvent or a mixture of water and an organic solvent as a solvent. The non-photosensitive silver aliphatic carboxylate particles are, in the presence of a tertiary alcohol, a solution containing silver ion containing water or a mixture of water and an organic solvent, and water, an organic solvent, or water and an organic solvent. The silver salt photothermographic dry imaging material according to claim 1, wherein the silver salt photothermographic dry imaging material is produced by reacting a solution containing an alkali metal salt of an aliphatic carboxylic acid with a mixture of the solvent and a solvent. Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material containing a binder, respectively, in the dry imaging material A silver salt photothermographic dry imaging material containing a cyan-coloring leuco dye and a binder containing a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. The silver salt photothermographic dry imaging material according to any one of claims 1 to 3, wherein the binder contains a latex of a polymer having an equilibrium water content of 2% by mass or less at 25 ° C and 60% RH. Non-photosensitive silver aliphatic carboxylate particles, a photosensitive emulsion containing photosensitive silver halide particles, a silver ion reducing agent, and a silver salt photothermographic dry imaging material each containing a binder, wherein the photothermographic imaging material is Each of the optical densities 0.5, 1.0, 1.5 and the minimum optical density of the silver image obtained after the heat development was measured, and the horizontal axis of the CIE 1976 (L ^* u ^* v ^* ) color space was expressed as u. ^* and the vertical axis the two-dimensional coordinates to v ^*, the u ^* at each optical density, v ^* was placed create determine coefficients of a linear regression line was (multiple determination) R ² is 0.998 or more, 1. 000 or less, and the v ^* value at the intersection with the vertical axis of the linear regression line is -5 or more and 5 or less, and the slope (v ^* / u ^* ) is 0.7 or more and 2.5 or less. The silver salt photothermography according to any one of claims 1 to 5, Lai imaging material. The image recording method for recording an image on a silver salt photothermographic dry imaging material according to any one of claims 1 to 6, wherein the exposure is performed by a laser beam scanning exposure device in which a scanning laser beam is a vertical multi. Image recording method. An image forming method, wherein the silver salt photothermographic dry imaging material according to any one of claims 1 to 6 is thermally developed in a state where the material contains an organic solvent in an amount of 40 to 4500 ppm.