JP2006292808A - Silver salt photothermographic dry imaging material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material containing a photosensitive silver halide emulsion having high sensitivity, low fog, excellent light stability of an image and excellent raw stock preservability, and capable of maintaining high sensitivity and low fog even after long-term storage. <P>SOLUTION: The silver salt photothermographic dry imaging material has on a support the photosensitive emulsion containing non-photosensitive silver salt of aliphatic carboxylic acid particles and photosensitive silver halide grains, a reducing agent for silver ions, a binder and a crosslinking agent, wherein the photosensitive silver halide grains are surface latent image type grains before heat development and change to internal latent image type grains after heat development, and the silver salt photothermographic dry imaging material has a layer containing at least one compound represented by formula (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silver salt photothermographic dry imaging material (hereinafter also referred to as “photothermographic material”) having a light-sensitive emulsion layer having low fog, high sensitivity, silver tone, storage stability and excellent light resistance after development, and The present invention relates to an image forming method using the same.

  Conventionally, in the fields of medical treatment and printing plate making, waste liquids resulting from wet processing of image forming materials have been a problem in terms of workability. In recent years, reduction of processing waste liquids is strongly desired from the viewpoint of environmental conservation and space saving. It is rare.

  As this technique, a silver salt photothermographic dry imaging material having an organic silver salt, photosensitive silver halide grains, a reducing agent and a binder on a support is known.

  The silver salt photothermographic dry imaging material has the disadvantage that the pre-development preservability is significantly worse than the photosensitive material for wet processing because all the materials related to development are incorporated in the silver salt photothermographic dry imaging material.

  Since the photosensitive silver halide grains of the silver salt photothermographic dry imaging material remain after heat development, light resistance and image storage after heat development are required. In the exposure before thermal development, a latent image that can function as a catalyst for a development reaction (reduction reaction of silver ions by a silver ion reducing agent) is formed on the surface of the silver halide grains. Since a larger number of latent images are formed inside the surface of the silver halide grains, the silver halide grains are preferred in which the formation of latent images on the surface is suppressed.

  Heretofore, silver halide grains (latent silver halide grains in heat conversion) whose latent image forming function changes before and after heat development processing have not been known.

  In general, when the photosensitive silver halide grains are exposed, the adsorbed spectral sensitizing dye is excited on the silver halide grains themselves or on the surface of the photosensitive silver halide grains, and freely moveable electrons. Although generated, this electron is trapped by an electron trap (photosensitive center) existing on the surface of the silver halide grain or an electron trap (capture) inside the grain. Therefore, when there are more and more appropriate chemical sensitization centers (chemical sensitization nuclei) or dopants on the surface than the inside of the silver halide grains, which are effective as electron traps, a latent image is preferentially formed on the surface and developed. It becomes possible.

  On the other hand, when there are a large number of chemical sensitization centers, dopants, and the like effective as electron traps inside the silver halide grain surface, a latent image is preferentially formed inside, and development becomes difficult. In other words, in the former case, the surface sensitivity is higher than in the interior, and in the latter case, the surface sensitivity is lower than in the interior. Although disclosed in many documents as described above, none is applied to silver salt photothermographic Dora imaging materials.

  On the other hand, there is a thermal image forming system using a reducible silver salt, but a silver salt photothermographic Dora imaging material generally has a catalytically active amount of a photocatalyst (for example, silver halide), a reducing agent, a reducible silver salt. (For example, a non-photosensitive aliphatic carboxylic acid silver salt), and if necessary, a photosensitive layer in which a color toning agent for controlling the color tone of silver is dispersed in a matrix of a binder.

  The silver salt photothermographic Dora imaging material is heated to a high temperature (for example, 80 ° C. or higher) after image exposure, and blackened by a redox reaction between a reducible silver salt (functioning as an oxidizing agent) and the reducing agent. Form a silver image. The oxidation-reduction reaction is promoted by the catalytic action of the latent image of silver halide generated by exposure. Therefore, many literatures disclose that a black silver image is formed in an exposed region (for example, Patent Documents 1 and 2).

  The reducible silver salts used in these silver salt photothermographic Dora imaging materials are relatively stable to light, but the presence of an exposed photocatalyst (such as a latent image of photosensitive silver halide) and a reducing agent Below, silver salts are used that form a silver image when heated to 80 ° C. or higher. Many such non-photosensitive, reducible silver salts have been disclosed.

  Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids having 10 to 30 carbon atoms, preferably 15 to 28 carbon atoms, are used. Examples thereof include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and mixtures thereof. Also disclosed are silver salts of sulfonic acids, silver complexes of tetrazole derivatives, complexes of triazole derivatives, and silver salts of methacrylic acid / styrene copolymer polymers. An example in which silver dicarboxylate linear alkylmonocarboxylate and linear alkyldicarboxylic acid are used in combination is disclosed.

  These non-photosensitive reducible silver salts are a reducible silver source (functioning as silver oxide) and a reducing agent when heated to a high temperature (for example, 80 ° C. or higher) in the presence of a reducing agent after exposure. Silver is produced through an oxidation-reduction reaction. This redox reaction is promoted by the catalytic action of the latent image generated by exposure. The silver produced by the reaction of the reducible silver salt in the exposed areas provides a black image that contrasts with the unexposed areas and forms an image. Further, silver salt photothermographic dry imaging materials using silver iodide (AgI) are disclosed for improving image light resistance after development, but none of them has sufficient sensitivity and fog (for example, Patent Documents 3 and 4).

Therefore, it is possible to obtain a photosensitive material with high sensitivity, low fog, light resistance after development (density fluctuation, color tone fluctuation), and excellent pre-exposure storage stability (fogging increase, sensitivity fluctuation). A technique for providing a silver salt photothermographic dry imaging material advantageous in terms of energy saving has been desired.
US Pat. No. 2,910,377 Japanese Patent Publication No.43-4924 JP 2003-91052 A European Patent 1,308,776

  It is an object of the present invention to provide a silver salt photothermographic dry imaging material containing a photosensitive silver halide emulsion having high sensitivity, low fog, excellent image light stability and raw storage stability. It is an object of the present invention to provide a silver salt photothermographic dry imaging material that can maintain high sensitivity and low fog.

  The above object of the present invention has been achieved by the following constitution.

(Claim 1)
In a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide particles on a support, a silver salt photothermographic dry imaging material having a silver ion reducing agent, a binder and a crosslinking agent, the photosensitivity The silver halide grains are surface latent image type grains before heat development, change to internal latent image type grains after heat development, and contain at least one compound represented by the following general formula (1) A silver salt photothermographic dry imaging material, characterized by comprising:

[Wherein R ₁ represents an aliphatic group, T ₁ represents an alkylene group, A ₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₁ represents a tertiary group. An amino group and a quaternary ammonium group are represented. Z ₁ and Z ₂ each represent a group of nonmetallic atoms necessary to form a 5-membered or 6-membered nitrogen-containing heterocycle, L _{1 to} L ₅ each represent the same or different methine groups, and M ₁ represents Represents an ion having a charge necessary to neutralize the charge of the molecule, r1 represents a number necessary to neutralize the charge of the whole molecule, l1 and q1 each represents 0 or 1, and m1 represents 1 or 2 is represented. ]
(Claim 2)
The silver salt photothermographic dry imaging material according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein R ₁₁ represents an aliphatic group, T ₁₁ represents an alkylene group, A ₁₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₁₁ represents a tertiary group. Represents an amino group or a quaternary ammonium group. Z ₁₁ and Z ₁₂ each represent a group of non-metallic atoms necessary to form a 5-membered nitrogen-containing heterocycle, L _{11 to} L ₁₇ each represent the same or different methine groups, and M ₁₁ represents molecular charge. Represents an ion having a charge necessary to neutralize, r11 represents a number necessary to neutralize the charge of the whole molecule, and q11 represents 0 or 1. ]
(Claim 3)
The silver salt photothermographic dry imaging material according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (3).

[Wherein R ₂₁ represents an aliphatic group, T ₂₁ represents an alkylene group, A ₂₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₂₁ represents a tertiary group. Represents an amino group or a quaternary ammonium group. Z ₂₁ represents a nonmetallic atom group necessary for forming a 5-membered or 6-membered condensed ring, and X ₂₁ represents an oxygen atom, a sulfur atom or a selenium atom. Each V ₂₁ and V ₂₂ represents a hydrogen atom, an aryl group, a heterocyclic group, represents a thioether group or a sulfinyl group, never V ₂₁ and V ₂₂ are hydrogen atoms at the same time, M ₂₁ medium-charged molecules This represents an ion having a charge necessary for summation, r21 represents a number necessary for neutralizing the charge of the whole molecule, and q21 represents 0 or 1. ]
(Claim 4)
In a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide particles on a support, a silver salt photothermographic dry imaging material having a silver ion reducing agent, a binder and a crosslinking agent, the photosensitivity The silver halide grains are surface latent image type grains before heat development, change to internal latent image type grains after heat development, and at least one compound represented by the following general formula (D) The silver salt photothermographic dry imaging material according to claim 1, comprising a layer containing a combination of at least one compound represented by the general formula (1).

[Wherein, R ₃₁ and R ₃₂ each independently represents an aliphatic group, Z ₃₁ represents a nonmetallic atom group necessary for forming a 5-membered or 6-membered condensed ring, X ₃₁ represents an oxygen atom, Represents a sulfur atom or a selenium atom. Each V ₃₁ and V ₃₂ represents a hydrogen atom, an aryl group, a heterocyclic group, represents a thioether group or a sulfinyl group, never V ₃₁ and V ₃₂ are hydrogen atoms at the same time, M ₃₁ medium-charged molecules It represents an ion having a charge necessary for summation, and r31 represents a number necessary for neutralizing the charge of the whole molecule. ]
(Claim 5)
In a silver halide photothermographic dry imaging material having a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide grains on a support, a silver ion reducing agent, a binder and a crosslinking agent, the following general formula It has a layer containing at least 1 sort (s) of the compound represented by (N), The silver salt photothermographic dry imaging material of any one of Claims 1-4 characterized by the above-mentioned.

[Wherein, R ⁴¹ , R ⁴² , R ⁴³ and R ⁴⁴ each independently represent a hydrogen atom or a substituent, and R ⁴¹ , R ⁴² , R ⁴³ and R ⁴⁴ are bonded to each other to form a saturated or unsaturated group. A ring may be formed. ]
(Claim 6)
The silver salt photothermographic dry imaging material according to any one of claims 1 to 5, wherein the photosensitive silver halide grains are not mixed when the non-photosensitive aliphatic carboxylic acid silver salt grains are formed. Silver salt photothermographic dry imaging material.

(Claim 7)
An image forming method comprising: exposing the silver salt photothermographic dry imaging material according to any one of claims 1 to 6 to heat and developing at 80 to 150 ° C for 5 to 20 seconds.

  According to the present invention, silver salts for laser imagers and imagesetter output films having high sensitivity, low fog, high maximum density, excellent silver tone and image storage stability, and good storage stability before processing. A photographic dry imaging material and an image forming method using the same were obtained.

  The photothermographic material of the present invention will be described in detail below.

  Various additives such as photosensitive silver halide, organic fatty acid silver salt, binder and crosslinking agent used in the silver salt photographic dry imaging material of the present invention, coating technique, exposure, and development conditions will be described in order.

(Heat conversion inner latent type silver halide grains)
The photosensitive silver halide used in the present invention is a silver halide grain which is of a surface latent image type before thermal development and changes to an internal latent image type grain after thermal development. The silver halide grains can be obtained by internally doping fine silver sulfide having a hole trap effect, silver nuclei, metal, or the like during grain growth.

  The silver halide grains are aggregated by the heat of development, and the micronuclei doped therein are aggregated and converted into a strong electron trap effect.

  The photosensitive silver halide grains used in the present invention can be obtained by subjecting so-called chemical sensitization such as reduction sensitization, chalcogen, noble metal sensitization, etc. during the growth of silver halide grains. Particularly preferably, it is applied to the core portion of the silver halide grains.

  In the present invention, the core portion of the particle refers to a portion of 0 to 99 mol% of the silver amount of one particle. Preferably it is 0-50 mol%.

  In general, as specific compounds for reduction sensitization, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. are used in addition to ascorbic acid and thiourea dioxide. Can do. Further, reduction sensitization can be performed by maintaining the pH during particle formation at 6.5 to 10.0 and ripening.

  In the present invention, it is preferable to use a chalcogen releasing compound represented by the following general formula (C-1) or (C-2). The pH when growing the core portion of the photosensitive silver halide grain of the present invention is 4.0 to 10.0, preferably 5.5 to 8.0, and the formation of silver chalcogenide is performed.

  Since the chalcogen-releasing compound represented by formula (C-1) or (C-2) can control the formation of silver chalcogenide depending on the pH, the formation of large fog nuclei on the surface of photosensitive silver halide grains is suppressed. Is done.

In the general formula (C-1), Z ₁ , Z ₂ and Z ₃ may be the same or different from each other, and are aliphatic group, aromatic group, heterocyclic group, —OR ₇ , —NR ₈ (R ₉ ). , -SR ₁₀ , -SeR ₁₁ , a halogen atom, or a hydrogen atom. R ₇ , R ₁₀ and R ₁₁ represent an aliphatic group, an aromatic group, a heterocyclic group, a hydrogen atom or a cation, and R ₈ and R ₉ represent an aliphatic group, an aromatic group, a heterocyclic group or a hydrogen atom. . Z ₁ and Z ₂ , Z ₂ and Z ₃ , and Z ₃ and Z ₁ may form a ring with each other. Chalcogen represents sulfur, selenium or tellurium.

In the general formula (C-2), Z ₄ and Z ₅ may be the same or different, and an alkyl group, an alkenyl group, an aralkyl group, an aryl group, a heterocyclic group, —NR ₁ (R ₂ ), —OR ₃ Or SR ₄ , and R ₁ , R ₂ , R ₃ and R ₄ may be the same or different and each represents an alkyl group, an aralkyl group, an aryl group or a heterocyclic group. However, R ₁ and R ₂ may be a hydrogen atom or an acyl group. Z ₄ and Z ₅ may form a ring. Chalcogen represents sulfur, selenium or tellurium.

  Although the specific example of a compound represented by general formula (C-1) or (C-2) below is given, this invention is not limited to these.

  The chalcogen compound represented by the general formula (C-1) or (C-2) is water or a suitable organic solvent such as alcohols (methanol, ethanol, propanol, fluorinated alcohol), ketones (eg acetone, methyl ethyl ketone). ), Dimethylformamide, dimethyl sulfoxide, methyl cellosolve and the like.

  In addition, using a well-known emulsification dispersion method, it is dissolved using an oil such as dimethyl phthalate, tricresyl phosphate, glyceryl triacetate or diethylene phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically emulsified and dispersed. An object can be made and used.

  Further, the powder of the chalcogen compound represented by the general formula (C-1) or (C-2) is mixed with water or an organic solvent by a ball mill, a colloid mill, or an ultrasonic wave by a method known as a solid dispersion method. Can be dispersed and used.

  A thiosulfonic acid compound may be added to the silver halide emulsion of the present invention by the method shown in European Patent Publication EP293,917.

  In the light-sensitive silver halide grains according to the present invention, it is preferable in terms of sensitivity and image storability that an electron-trapping dopant is included in the silver halide grains. The dopant silver halide functions as a positive (hole) trap during exposure for image formation before thermal development, changes in quality during thermal development, and functions as an electron trap after thermal development. Particles are particularly preferred.

  When photoconductive measurement is performed on a coated sample of a light-sensitive silver halide grain emulsion, the photoconductivity after heat development of the heat conversion inner latent type silver halide grain emulsion according to the present invention is reduced to 80% or less before heat development. To do. Preferably it falls to 50% or less. More preferably, it is reduced to 25% or less.

  The phenomenon that the photoconductivity decreases means that the electron trap effect has been converted.

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

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

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

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

  In addition, the silver halide grains used in the present invention have a group 6 to group 11 in the 18-group periodic table so as to function as an electron trapping dopant like the above-mentioned dopants or as a hole trapping dopant. Transition metal ions belonging to the above may be contained by chemically adjusting the oxidation state of the metal with a ligand or the like.

  As the transition metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, and Pt are more preferable. In the present invention, these metal-doped ions are performed inside the particles. The inside of the grain refers to a place of 0 to 99 mol% of the silver amount of one grain, preferably 0 to 50 mol%.

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

  In the present invention, an embodiment in which any one of Ir or Cu complex or salt is used alone and doped is excluded from the present invention.

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

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

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

General formula [ML ₆ ] _m
In the formula, M represents a transition metal selected from Group 6 to 11 elements of the Group 18 element periodic table, L represents a ligand, and m represents 0, 1-, 2-, 3-, or 4-. Specific examples of the ligand represented by L include halogen ions (for example, fluorine ion, chlorine ion, bromine ion, iodine ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Each ligand includes nitrosyl, thionitrosyl, and the like, preferably aco, nitrosyl, thionitrosyl, and the like. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

  The compounds providing these metal ions or complex ions are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening In addition, it may be added at any stage before or after chemical sensitization, but is particularly preferably added at the stage of nucleation, growth, physical ripening, and more preferably added at the stage of nucleation, growth, Most preferably, it is added at the stage of nucleation.

  In addition, it may be added in several divided portions, and can be added uniformly in 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, etc., the particles can be contained with a distribution.

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

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

  In the imaging material according to the present invention, whether or not the dopant has an electron trapping property can be evaluated by a method generally used in the photographic industry as follows.

  That is, a silver halide emulsion comprising silver halide grains in which the dopant or a decomposition product thereof is doped in silver halide grains is subjected to photoconductivity measurement by a microwave photoconductivity measurement method. It can be evaluated by measuring the degree of decrease in photoconduction based on silver halide grains. Alternatively, it can be performed by a comparative experiment of the internal sensitivity and surface sensitivity of the silver halide grains.

  Further, after the photothermographic dry imaging material is used, the method for evaluating the effect of the electron trapping dopant according to the present invention is, for example, according to the normal photothermographic dry imaging material before exposure of the photothermographic dry imaging material. Heating is performed under the same conditions as prescribed predetermined practical heat development conditions, and then exposed through an optical wedge with light in a range of ultraviolet to visible light or spectrally sensitized for a certain period of time (for example, 30 seconds), and the same heat development By comparing the sensitivity obtained based on the characteristic curve (sensitometry curve) obtained by thermal development under the conditions with the sensitivity of the photothermographic dry imaging material using the silver halide grain emulsion not containing the electron trapping dopant Can be evaluated.

  That is, it is necessary to confirm that the sensitivity of the former sample containing the silver halide grain emulsion containing the dopant according to the present invention is lower than the sensitivity of the latter sample not containing the dopant.

  In addition, after exposing the photothermographic dry imaging material through an optical wedge with light in a range of ultraviolet to visible light or spectrally sensitized for a certain time (for example, 30 seconds), a predetermined heat development usually determined by the photothermographic dry imaging material For the sensitivity of the sample obtained based on the characteristic curve obtained when heat development is performed under the conditions, the sample is heated under normal heat development conditions before exposure, and then subjected to the same constant time and constant exposure as described above. Further, the sensitivity obtained from the characteristic curve obtained by heat development under normal heat development conditions is 1/5 or less, preferably 1/10 or less, more preferably 1/20 or less.

  The photosensitive silver halide of the present invention functions as an optical sensor, and it is preferable that the grain size is small in order to suppress white turbidity after image formation and to obtain good image quality.

  The average grain size of the photosensitive silver halide grains is 0.08 μm or less, preferably 0.01 to 0.08 μm, particularly preferably 0.02 to 0.06 μm. The content of the small size particles is preferably 70% or more.

  On the other hand, for sensitivity and gradation adjustment, slightly larger particles are preferable, and the average particle size is 0.1 μm or less, preferably 0.04 to 0.1 μm, particularly preferably 0.05 to 0.08 μm. The content of the large size particles is preferably 30% or less.

  Examples of the shape of the silver halide grains include cubic grains, octahedral grains, tabular grains, spherical grains, rod-shaped grains, and potato-like grains. In the present invention, octahedral grains, cubic grains, tabular grains, etc. Particles are preferred.

  The average aspect ratio when using tabular silver halide grains is preferably 100: 1 to. 2: 1, more preferably 50: 1 to 3: 1. Further, grains having rounded corners of silver halide grains can be preferably used.

  The surface index (Miller index) of the outer surface of the photosensitive silver halide grain is not particularly limited, but the ratio of the [100] plane having high spectral sensitization efficiency when the spectral sensitizing dye is adsorbed is high. preferable. The ratio is 50% or more, more preferably 65% or more, and particularly preferably 80% or more.

  The ratio of the Miller index [100] plane is determined by T.T. based on the adsorption dependency of the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985). The silver halide composition is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

  The amount of the photosensitive silver halide is preferably 2 to 8%, more preferably 3 to 6% in terms of the silver ratio with respect to the non-photosensitive aliphatic carboxylate silver described later as a photothermographic dry imaging material. .

  The silver halide emulsion in the photothermographic dry imaging material used in the present invention may be only one type or two or more types (for example, those having different average grain sizes, those having different halogen compositions, and those having different crystal habits). You may use together.

  The amount of the photosensitive silver halide used is preferably 0.01 to 0.5 mol, more preferably 0.02 to 0.3 mol, and 0.03 mol per mol of the organic silver salt. -0.25 is particularly preferred.

  Regarding the mixing method and mixing conditions of the photosensitive silver halide and the organic silver salt prepared separately, the silver halide particles and the organic silver salt that have been prepared are respectively mixed with a high-speed stirrer, ball mill, sand mill, colloid mill, vibration mill, There are a method of mixing with a homogenizer or the like, or a method of preparing an organic silver salt by mixing photosensitive silver halide that has been prepared at any timing during the preparation of the organic silver salt. There is no particular limitation as long as it appears sufficiently.

  Typically, silver halide emulsions are mixed with a silver salt aqueous solution and a halide aqueous solution in a protective colloid solution (a hydrophilic colloid such as gelatin is used) as a reaction mother liquor to produce nucleation and crystal growth. The double jet method is generally used as a method for adding a halide aqueous solution or a silver salt aqueous solution. Among them, the cotrol double jet method in which each component is mixed while controlling pAg and pH to perform the nucleation and crystal growth is representative.

  In addition, various variations are included such as a method in which seed particles are first prepared (nucleated), and then this growth is continuously performed under the same conditions or under different conditions (crystal growth or aging). . In short, it is well known in the art that various crystal habits and sizes are controlled by defining the mixing conditions of the silver salt aqueous solution and the halide aqueous solution in the mixing step in the protective colloid aqueous solution. Subsequent to these mixing steps, a desalting step for removing excess salts from the prepared emulsion is performed.

  As the desalting step, there is a flocculation method in which a silver halide grain is coagulated and precipitated together with gelatin, which is a protective colloid, by adding a flocculant to the prepared silver halide emulsion, and this is separated from a supernatant containing salts. well known. The supernatant is removed by decantation, and further dissolution, flocculation, and decantation are repeated to remove excess salts contained in the gelatin coagulation containing silver halide grains that have coagulated and settled. Ultrafiltration is also performed. A method for removing soluble salts by a method is also well known. This is a method of removing unnecessary low molecular weight salts by using an ultrafiltration membrane and using a synthetic membrane that does not permeate large grains such as silver halide grains and gelatin and molecules having a large molecular weight.

  The hydrophilic colloid contained in the photosensitive silver halide preferably used in the present invention is preferably 40 g or less, particularly preferably 35 g or less, per 1 mol of silver.

  The photosensitive silver halide emulsions prepared by the various methods described above can be chemically sensitized on the surface of these grains. For example, chemical sensitization can be performed with a sulfur-containing compound, a gold compound, a platinum compound, a palladium compound, a silver compound, a tin compound, a chromium compound, or a combination thereof. Regarding the method and procedure of this chemical sensitization, for example, U.S. Pat. No. 4,036,650, British Patent 1,518,850, JP-A-51-22430, 51-78319, 51-81124. It is described in the issue. Also, in order to achieve sensitization as described in U.S. Pat. No. 3,980,482 when a part of the organic silver salt is converted into photosensitive silver halide by the silver halide forming component. In addition, an amide compound having a low molecular weight may coexist.

  As described in British Patent No. 1,447,454, when preparing aliphatic carboxylic acid particles, a halogen component such as a halide ion coexists with an aliphatic carboxylic acid silver salt forming component, and silver By injecting ions, silver halide grains produced almost simultaneously with the production of the aliphatic carboxylate silver salt grains can be used in combination.

  It is also possible to prepare a silver halide grain by converting a halogen-containing silver salt to an aliphatic carboxylic acid silver salt and converting the aliphatic carboxylic acid silver salt, and use the grain together.

  That is, a silver halide-forming component is allowed to act on a solution or dispersion of an aliphatic carboxylic acid silver salt prepared in advance or a sheet material containing an organic silver salt, so that a part of the aliphatic carboxylic acid silver salt is photosensitive halogenated. It can also be converted to silver fossil.

  The photosensitive silver halide grain of the present invention may be added to the photosensitive layer by any method, and at this time, the silver halide grain is arranged so as to be close to a reducible silver source (aliphatic carboxylic acid silver salt). However, it is possible to prepare the silver halide grains of the present invention in advance and add them to the aliphatic carboxylate silver salt grains to prepare the silver halide grain preparation step and the aliphatic carboxylate silver salt grain preparations. The process can be handled separately, which is preferable in terms of production control.

  In addition, the silver halide of the present invention can be dispersed from a water-soluble solvent into an organic solvent, and added and dispersed in a coating solution of an aliphatic carboxylic acid silver salt immediately before coating. The silver halide of the present invention can also be prepared in an organic solvent.

  Examples of the silver halide forming component include inorganic halogen compounds, onium halides, halogenated hydrocarbons, N-halogen compounds, and other halogen-containing compounds. Specific examples thereof include US Pat. No. 4,009,039, No. 3,457,075, No. 4,003,749, British Patent No. 1,498,956, JP-A-53-27027, No. 53-25420, and the like.

  As described above, silver halide grains produced by converting a part of the aliphatic carboxylic acid silver salt into silver halide grains separately prepared may be used in combination.

  These silver halide grains are separately prepared silver halide grains, 0.001 to 0.7 mol per 1 mol of aliphatic carboxylic acid silver salt, and silver halide grains obtained by conversion of aliphatic carboxylic acid silver salt. Preferably it is used at 0.03-0.5 mol.

  Separately prepared silver halide grains can be desalted by a known desalting method such as noodle method, flocculation method, ultrafiltration method, electrodialysis method, etc. It can be used without desalting.

  Next, the compounds represented by the general formula (1), general formula (2) and general formula (3) of the present invention will be described.

In the general formula (1), general formula (2), and general formula (3), examples of the aliphatic group represented by R ₁ , R _11, and R ₂₁ include an alkyl group, an alkenyl group, and an alkynyl group. The alkyl group is preferably a linear or branched lower alkyl group having 1 to 5 carbon atoms, specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec- Examples thereof include a butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a 2-methylpropyl group, and a 1,1-dimethylpropyl group. The alkenyl group is preferably a straight chain having 3 to 5 carbon atoms or A branched lower alkenyl group, specifically, an allyl group, a 2-butenyl group, an isobutenyl group, and the like. The alkynyl group is preferably a linear or branched lower alkynyl group having 3 to 5 carbon atoms. Group, specifically 2-propyl group, 2-butenyl group and the like, and these may have a substituent, and may be an alkyl group (for example, methyl, ethyl, etc.). Each group), a cycloalkyl group (for example, each group such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.), a trifluoromethyl group, an alkenyl group (for example, each group such as vinyl, propenyl group), a cycloalkenyl group (for example, Each group such as cyclopentenyl and cyclohexenyl group), alkynyl group (for example, each group such as ethynyl and carboxyethynyl), aryl (for example, each group such as phenyl and p-carboxyphenyl, each group in o-tolyl and the like) , Amino groups (for example, dimethylamino, N-benzyl, N-methylamino, etc.), alkoxy groups (for example, methoxy, 2-methoxyethoxy, propoxy, etc.), aryloxy groups (for example, phenoxy, each group such as m-chlorophenyl), acyl group (for example, acetyl, benzoyl, p Each group such as dimethylaminobenzoyl), alkoxycarbonyl group (for example, each group such as methoxycarbonyl and ethoxycarbonyl), aryloxycarbonyl group (for example, each group such as phenoxycarbonyl, o-methoxycarbonyl), acyloxy group (for example, , Acetyloxy, trifluoroacetyloxy, etc.), acylamino groups (eg, acetylamino, benzoylamino, etc.), thioamide groups (eg, thioacetamide, thiobenzoylamide, etc.), alkoxy A carbonylamino group (for example, an oxycarbonylamino group), an aryloxycarbonylamino group (for example, each group such as phenoxycarbonylamino, 5,6-dimethoxycarbonylamino), a sulfonylamino group (for example, methanesulfonylamino) , Each group such as p-toluenesulfonylamino), sulfamoyl group (for example, each group such as sulfamoyl, N, N-dimethylsulfamoyl, morpholinosulfamoyl), carbamoyl group (for example, carbamoyl, N-methylcarbamoyl, Each group such as N, N-tetramethylenecarbamoyl), alkylthio group (for example, each group such as methylthio, ethylthio), arylthio (for example, phenylthio group), heterocyclic thio group (for example, 2-thienylthio, 3-thienylthio) , 2-imidazolylthio, etc.), cyano group, alkylsulfonyl group (eg, methanesulfonyl, butanesulfonyl, trifluoromethanesulfonyl, etc.), alkylsulfonyl group (eg, methanesulfonyl, butanesulfonyl, trifluoromethanesulfonyl) Etc. ), Arylsulfonyl groups (eg, groups such as benzenesulfonyl, toluenesulfonyl, p-dimethylaminobenzenesulfonyl), sulfinyl groups (eg, groups such as methanesulfinyl, benzenesulfinyl, m-chlorophenylsulfinyl, thienylsulfinyl, etc.), ureido Group (for example, each group such as ureido, 3-methylureido, 1,3-dimethylureido), thioureido group (for example, each group such as thioureido, 3-methylthioureido), phosphoramide group, hydroxy group, mercapto group , Halogen atoms (eg, fluorine, chlorine, bromine, iodine, etc.), hydrazino groups, silyl groups, heterocyclic groups (eg, oxazolyl, thiazolyl, pyrrolyl, furyl, pyridyl, morpholyl, morpholino, thienyl, etc.) ), Cal Xyl group, sulfo group, phosphono group, sulfate group, sulfonylaminocarbonyl group (for example, each group such as methanesulfonylaminocarbonyl and ethanesulfonylaminocarbonyl), acylaminosulfonyl group (for example, acetamidosulfonyl, methoxyacetamidosulfonyl, etc.) Group), acylaminocarbonyl group (for example, each group such as acetamidocarbonyl, methoxyacetamidocarbonyl, etc.), sulfinylaminocarbonyl group (for example, each group such as methanesulfinylaminocarbonyl, ethanesulfinylaminocarbonyl), etc. Can be replaced with a position.

The alkylene group represented by T ₁ , T ₁₁ and T ₂₁ is a group having 1 to 8 carbon atoms, and examples thereof include groups such as methylene, ethylene, propylene, butylene and hexylene. Specific examples of the arylene group in the arylene group, O-arylene group and S-arylene group represented by A ₁ , A ₁₁ and A ₂₁ are 1,4-phenylene, 1,3-phenylene, 1, Examples include 4-naphthylene, 1,5-naphthylene, and the like. Specific examples of the alkylene group in the O-alkylene group and the S-alkylene group include a part of carbon atoms in addition to the group defined by T _1. Is a group in which oxygen element or sulfur element is substituted, for example, ethylene, propylene, 3-oxapentalene, 4-oxaheptane, 3-thiapentalene, 4-thiaheptane, etc., and these groups include R ₁ , it may have a substituent mentioned in R ₁₁ and R _21.

The tertiary amino group represented by Q ₁ , Q ₁₁ and Q ₂₁ includes a cyclic structure containing a nitrogen atom. Specific examples thereof include N, N-dimethylamino, N, N-diethylamino, N-ethyl- Examples include N-methylamino, N-benzyl-N-methylamino, pyrrolino, morpholino, pyrrolidino, and the like. The quaternary amino group includes a cyclic structure containing a nitrogen atom. Specific examples include N, N, N-trimethylammonium, N, N, N-triethylammonium, N-ethyl-N, N-dimethylammonium, N-benzyl-N, N-dimethylammonium, pyridinio, pyrimidinio, N-methylpyrrolidinino, etc. Each group is mentioned.

Z _1, Z ₂ 6-membered nitrogen-containing heterocyclic group formed by, Z _1, Z _2, 5-membered nitrogen-containing heterocyclic group formed by Z ₁₁ and Z ₁₂ each, carbocycle, a benzene ring, A condensed ring may be formed by a naphtho ring and a hetero ring. Specific examples of the 6-membered nitrogen-containing heterocyclic group in which Z ₁ is formed include, for example, cyclic groups such as pyridine (2-, 4-) and quinoline (2-, 4-), and Z ₂ is Specific examples of the 6-membered nitrogen-containing heterocyclic group to be formed include cyclic groups such as pyridine (2-) and quinoline (2-), and 5-membered nitrogen-containing formed by Z ₁ and Z ₂ respectively. Specific examples of the heterocyclic group (azole ring group) include, for example, oxazolidine, oxazoline, oxazole, 4,5-trimethyleneoxazole, 4,5,6,7-tetrahydrobenzoxazole, benzoxazole, naphtho [1 , 2-d] oxazole, naphtho [2,3-d] oxazole, thiazoline, thiazole, 4,5-trimethylenethiazole, 4,5,6,7-tetrahydrobenzothiazole, benzothiazole, naphtho 1,2-d] thiazole, naphtho [2,3-d] thiazole, thieno [2,3-d] thiazole, thieno [3,2-d] thiazole, thieno [2,3-d] benzothiazole, benzofurano Examples include cyclic groups such as [2,3-e] benzothiazole, seranazole, selenazoline, benzoselanazole, naphtho [1,2-d] selanazole, imidazole, benzimidazole, naphthimidazole, indole, indolenine, and benzotelrazole. In the present invention, a benzothiazole ring is preferred.

  The azole ring may have a substituent at any position, for example, an alkyl group (for example, each group such as methyl, ethyl, propyl, t-pentyl, isobutyl, etc.), a halogen atom (for example, fluorine, chlorine) , Bromine, iodine, etc.), trifluoromethyl group, alkoxy group (eg, methoxy, butoxy, 2-methoxyethoxy, benzyloxy, etc.), alkyl mercapto group (eg, methyl mercapto, ethyl mercapto, etc.) Each group), hydroxy group, cyano group, aryloxy group (eg, substituted or unsubstituted groups such as phenoxy and tolyloxy), heterocyclic oxy group (eg, 2-thienyloxy, 2-furyloxy, 2-imidazolyl) Each group such as oxy), arylthio group (for example, each group such as phenylthio, dimethylaminophenylthio) complex Thio group (for example, 2-thienylthio, 3-thienylthio, 2-imidazolylthio, etc.) or aryl group (for example, phenyl, p-chlorophenyl, etc., substituted or unsubstituted groups), styryl group, heterocyclic group (For example, each group such as furyl, thienyl, pyrrolyl), carbamoyl group (for example, each group such as carbamoyl, N-ethylcarbamoyl), sulfamoyl group (for example, each group such as sulfamoyl, N, N-dimethylsulfamoyl) ), Acylamino groups (eg, groups such as acetylamino, propionylamino, benzoylamino), acyl groups (eg, groups such as acetyl, benzoyl), alkoxycarbonyl groups (eg, groups such as ethoxycarbonyl), sulfonamides (For example, each group such as methanesulfonamide, benzenesulfonamide), Finiru group (e.g., methanesulfinyl, each group such as benzene sulfinyl), sulfonyl (e.g., methanesulfonyl, butanesulfonyl, p- toluenesulfonyl each group, etc.), can be any group is substituted, such as a carboxy group.

The 5-membered or 6-membered condensed ring formed by the nonmetallic atom group represented by Z ₂₁ is, for example, a heterocyclic condensed ring, a benzo condensed ring, or a naphtho condensed ring, and is arbitrarily located at any position on the condensed ring. Can be substituted. Specific examples of the substituents on these condensed rings include the groups mentioned for Z ₁ , Z ₂ , Z ₁₁ and Z ₁₂ .

Examples of the substituent of the methine group represented by L _{1 to} L ₅ and L _{11 to} L ₁₇ include a substituted or unsubstituted alkyl group (for example, methyl, ethyl, propyl, butyl, benzyl, 2-phenoxyethyl, 2- Substituted or unsubstituted groups such as sulfoethyl), lower alkylthio groups (for example, groups such as methylthio and ethylthio), halogen atoms (for example, atoms such as fluorine, chlorine, bromine and iodine), substituted or unsubstituted aryl Groups (eg, phenyl, alkyl-substituted phenyl, methoxy-substituted phenyl, naphthyl groups, etc.), heterocyclic groups (eg, furyl, thienyl, pyrrolyl, imidazolyl, pyrrolidyl, morpholyl, etc.), lower alkoxy groups (eg , Methoxy, ethoxy, etc.), amino group (for example, dimethylamino, pyrrolidino, morpholino, pyrrolino, 2-oxopi Groups such as loridino). Further, substituents of the methine group may be bonded to form a 5-membered to 7-membered ring containing three methine groups, and this ring further forms a condensed ring with a ring containing other methine groups. May be.

Preferable substituents for the methine group represented by L _{1 to} L ₅ and L _{11 to} L ₁₇ are an alkyl group, an amino group, and a heterocyclic group. Specific examples of the ring containing three methine groups formed by combining substituents of the methine groups represented by L _{1 to} L ₅ and L _{11 to} L ₁₇ include a cyclopentene ring, a cyclohexene ring, and 4, Examples thereof include a 4-dimethylcyclohexene ring, and a tetrahydronaphthalene ring is particularly preferable in the present invention.

In the compound represented by the general formula (3), specific examples of the aryl group, heterocyclic group, and sulfinyl group represented by V ₂₁ and V ₂₂ are R ₁ , R ₁₁ , and R ₂ 1, respectively. And the substituents mentioned in Z ₁ , Z ₂ , Z ₁₁ and Z ₁₂ , and specific examples of the thioether group include R ₁ , R ₁₁ and R ₂₁ , and Z ₁ , Z ₂ , Z ₁₁ and Z. alkylthio groups listed _12, arylthio group, and heterocyclic thio group, preferably an aryl group, a heterocyclic group, a sulfinyl group.

In the compounds represented by the general formulas (1) to (3), when a group having a cation or anion charge is substituted, an equal amount of anion is used so that the charge in the molecule is offset. Alternatively, counter ions are formed with cations. For example, in the ions necessary for canceling the charges in the molecule represented by M ₁ , M ₁₁ and M ₂₁ , specific examples of the cation include protons, organic ammonium ions (for example, triethylammonium, triethanolammonium, Each ion such as pyridinium) and inorganic cations (for example, each cation such as lithium, sodium, and potassium). Specific examples of the acid anion include, for example, halogen ions (for example, chlorine ions, bromine ions, iodine ions, etc.) ), P-toluenesulfonate ion, perchlorate ion, boron tetrafluoride ion, sulfate ion, methyl sulfate ion, ethyl sulfate ion, methanesulfonate ion, trifluoromethanesulfonate ion, hexafluorophosphate ion, etc. It is done.

  Specific examples of the compounds represented by the general formulas (1) to (3) are shown below, but the present invention is not limited to these.

  The above-mentioned sensitizing dyes are described in, for example, HM Hammer, The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanin Dies and Related Compounds, published by A. Weissgered. Ber. 64, 1664-1674 (1931), Ukrain Khim. Zhur. , 21, 744-9 (1955), British Patent Nos. 625,245, 895,930, U.S. Pat. Nos. 2,320,439, 2,398,999, and Japanese Patent Laid-Open No. 48-999. It can be easily synthesized by the method described in No. 24726.

  Below, the synthesis example of the compound of this invention is shown. The product field molecular structure was confirmed by proton and carbon-13 nuclear magnetic resonance analysis and mass spectrometry.

Synthesis of Exemplified Compound (64) 4.5 g of 6-phenylbenzothiazole, 9.4 g of 3-m-nitrobenzenesulfonyloxypropyl-N, N, N- and methylammonium tetrafluoroboron salt were mixed in 15 ml of m-cresol. And stirred at 120 ° C. for 3 hours. After cooling, acetone was added and the mixture was heated and stirred to cool uniformly as a dispersion. The crystallized product was collected by filtration, washed with acetone, and dried to obtain 5 g of a light brown powder.

  3.1 g of the obtained powder and 0.53 g of 2,7-dimethoxytetrahydronaphthalene were added to 2 ml of m-cresol and mixed with stirring, and then heated and dissolved in an oil bath at 110 ° C. for 10 minutes. The temperature of the oil bath was lowered to 80 ° C., 20 ml of ethanol containing 0.5 g of triethylamine was added, and the mixture was heated and stirred for 30 minutes. Crystals crystallized by cooling were collected by filtration, washed with cold ethanol and dried to obtain 1.0 g of crude crystals.

  The crude crystals were dissolved in 10 ml of 2,2,3,3-tetrafluoropropanol and filtered, and 2 ml of 50% aqueous methanol in which 0.3 g of sodium tetrafluoroborate was dissolved was added to the filtrate for crystallization with stirring. The precipitate was collected by filtration, washed with methanol and dried to obtain 0.7 g of a purified dye.

  The absorption maximum wavelength of the obtained dye in methanol was 768 nm (molar absorption coefficient: 248000).

  The photosensitive silver halide grain, which is a surface latent image type before the thermal development of the present invention and changes to an internal latent image type grain after the thermal development, is a compound represented by the general formula (1) By using together, the improvement of sensitivity and the reduction of fog density are remarkable.

  Although the photosensitive dye of the present invention may be used alone, it is preferable to obtain a higher sensitivity when a compound (photosensitive dye) represented by the following general formula (D) is used in combination.

When the sensitizing dyes of the present invention is used in combination and if used alone, per mol of silver halide, respectively in ^{total, 1 × 10 -6 ~5 × 10} -3 mol, preferably 1 × 10 ^- 5 It is contained in the silver halide emulsion in a proportion of ˜2.5 × 10 ⁻³ mol, more preferably 4 × 10 ⁻⁵ to 1 × 10 ⁻³ mol.

  In the present invention, when two or more photosensitive dyes are used in combination, the photosensitive dye can be contained in the silver halide emulsion in an arbitrary ratio.

  Further, the photosensitive dye of the present invention can be directly dispersed in an emulsion, and these are firstly used in an appropriate solvent such as methanol, ethanol, propanol, methyl cellosolve, acetone, methyl ethyl ketone, water, pyridine or a mixed solvent thereof. And can be added to the emulsion in the form of a solution. As a method for adding the photosensitive dye, as described in US Pat. No. 3,469,987, the dye is volatilely dissolved in an organic solvent, and the solution is dispersed in a hydrophilic colloid. A method of adding a product into an emulsion, as described in JP-B-46-24185, etc., a method in which a water-soluble dye is dispersed in a water-soluble solvent without dissolving it, and this dispersion is added to an emulsion; A method in which a dye is dissolved in a surfactant as described in No. 3,822,135 and the solution is added to the emulsion; a compound that shifts to the longer wavelength side as described in JP-A-51-74624 A method in which the dye is dissolved in an acid substantially free of water and the solution is added to the emulsion, as described in JP-A-50-80826. Etc. are preferably used. In addition, the method described in U.S. Pat. Nos. 2,912,343, 3,342,605, 2,996,287, 3,429,835 and the like is used for addition to the emulsion. Used. The photosensitive dye may be uniformly added to the silver halide emulsion before being coated on the support, but can be added at any stage of preparation of the silver halide emulsion.

  When two or more kinds of the photosensitive dyes of the present invention are combined, the photosensitive dyes can be dispersed in the silver halide emulsion by the above-mentioned method independently or in advance.

  Along with the photosensitive dye of the present invention, a dye having absorption in the visible range for the purpose of supersensitization, a dye having no spectral sensitization by itself, or a substance that does not substantially absorb visible light, Research Disclosure (Research Disclosure), 176, 17643 (issued in December, 1978), page 23, Section J, JP-B-49-25500, JP-A-43-4933, JP-A-59-19032 No. 59-192242, JP-A-3-15049, and JP-A-62-2123454.

  Next, the compound represented by the general formula (D) will be described.

In the general formula (D), R ₃₁ and R ₃₂ are respectively synonymous with R ₁ , R ₁₁ and R ₂₁ defined in the general formulas (1) to (3), and Z ₃₁ represents the general formula ( 3) has the same meaning as Z ₂ 1, V ₃₁ and V ₃₂ have the same meaning as V ₂₁ and V _{22 in} the general formula (3), respectively, and M ₃₁ in the general formulas (1) to (3). the same meaning as M _1, M ₁₁ and M ₂₁ defined.

Specific examples of the aryl group, heterocyclic group, thioether group, and sulfinyl group represented by at least one of V ₃₁ and V ₃₂ are R ₁ , R ₁₁ and R ₂₁ , and Z ₁ , Z ₂ , Z ₁₁ and Z, respectively. include substituents exemplified by _12, specific examples of thioether group, wherein R _1, Z ₁ as well as R ₁₁ and R _21, Z _2, alkylthio groups listed Z ₁₁ and Z _12, an arylthio group, a heterocyclic A cyclic thio group.

  Although the specific example of a compound represented by general formula (D) below is given, this invention is not limited to these.

  Next, the compound represented by formula (N) will be described.

In the general formula (N), R ^{41 to} R ⁴⁴ each independently represents a hydrogen atom or a substituent. R ^{41 to} R ⁴⁴ may combine with each other to form a saturated or unsaturated ring.

Examples of the substituent represented by R ^{41 to} R ⁴⁴ include a halogen atom (for example, each atom such as fluorine, chlorine, bromine, iodine, etc.), an alkyl group (for example, a linear, branched, or cyclic alkyl group, Bicycloalkyl group, including active methine group), alkenyl group, alkynyl group, aryl group, heterocyclic group (regarding the position of substitution), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, Carbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, carboxy or a salt thereof, oxalyl group, oxamoyl group, cyano group, Carboximidoyl group (Carbonimide group), formyl group, Hydroxy group, alkoxy group (including a group repeatedly containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group (each group such as alkoxy or aryloxy), carbonyloxy group, carbamoyloxy Group, sulfonyloxy group, amino group (each group such as alkyl, aryl or heterocycle) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfo group Famoylamino group, semicarbazide group, thiosemicarbazide group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, nitro group, quaternary Nitrogen source (For example, each group such as pyridinio, imidazolio, quinolinio, isoquinolinio), isocyano group, imino group, mercapto group, (alkyl, aryl or heterocycle) thio group, (alkyl, aryl or heterocycle) dithio Group, alkyl or arylsulfonyl group, alkyl or arylsulfinyl group, sulfo group or salt thereof, sulfamoyl group, N-acylsulfamoyl group, N-sulfonylsulfamoyl group or salt thereof, phosphino group, phosphinyl group, phosphini Examples include a ruoxy group, a phosphinylamino group, and a silyl group.

  Here, the active methylene group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a carbamoyl group. , An alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group.

  Here, the two electron-attracting groups may be bonded to each other to form a cyclic structure. The salt means a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion. These substituents may be further substituted with these substituents.

  Preferred substituents include the formation of phthalazine rings by alkyl groups, alkenyl groups, alkynyl groups, aryl groups, hydroxy groups, alkoxy groups, aryloxy groups, heterocyclic oxy groups, and benzo-fused rings.

  When a hydroxyl group is substituted on the carbon adjacent to the nitrogen atom of the compound represented by the general formula (N), an equilibrium exists with pyridazinone.

  The compound represented by the general formula (N) particularly preferably forms a phthalazine ring, and this phthalazine ring may further have a substituent. Preferable substituents on the phthalazine ring include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a hydroxy group, an alkoxy group, and an aryloxy group.

  Although the specific example of a compound represented by general formula (N) below is given, this invention is not limited to these.

  The compound represented by the general formula (N) in the present invention may be a common compound with the color tone agent when it functions as a conventionally known color tone agent. When the compound represented by formula (N) does not have a function as a color tone, it can be used in combination with the color tone. For example, in the pyridazine derivative (for example, phthalazine) represented by the general formula (N) of the present invention, there is a compound known as a color tone agent. However, phthalazine compounds have been known to be effective in photothermographic materials as color toning agents, but the compounds represented by the general formula (N) of the present invention have the function of a silver iodide complex forming agent. It was not known at all, and since the compound itself having the function of a silver iodide complex forming agent was not recognized and used, its function was not expected. When a phthalazine compound is used as a color tone agent, phthalazine may be used alone, or different phthalazine derivatives may be mixed and used.

  The compound represented by formula (N) in the present invention acts effectively without adversely affecting the raw storage stability of the silver salt photothermographic dry imaging material of the present invention and without interfering with the image forming reaction. It is desirable that the photosensitive silver halide does not act on the photosensitive silver halide until it is heated for heat development, and acts after the heating at a stage that does not substantially affect the heat development.

  For that purpose, the compound represented by the general formula (N) is preferably present in the film in a state separated from the photosensitive silver halide, such as being present in the film in a solid state, and added to the adjacent layer. It is also preferable to do.

  The compound represented by the general formula (N) in the present invention is a compound having a melting point of a compound in an appropriate range so as to melt when heated to a heat development temperature at a temperature below room temperature, or a melting point regulator. It is preferable to use a combination of means such as adjustment of the melting point by mixing.

  In the present invention, in order to greatly improve the image storability, particularly the image storability under light irradiation, the absorption intensity of the ultraviolet-visible absorption spectrum of the photosensitive silver halide after heat development is In comparison, it is preferably 80% or less, more preferably 40% or less, and particularly preferably 20% or less. Most preferably, it is 10% or less.

  The compound represented by the general formula (N) may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the silver salt photothermographic dry imaging material. Well-known emulsification dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethylene phthalate, and an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically emulsifying the dispersion. The method of producing is mentioned.

  As the solid fine particle dispersion method, the powder of the compound represented by the general formula (N) is dispersed in an appropriate solvent such as water by a ball mill, a colloid mill, a vibrating ball mill, a sand mill, a jet mill, a roller mill, or an ultrasonic wave. And a method of producing a solid dispersion.

  At this time, a protective colloid (for example, polyvinyl alcohol) and a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three different isopropyl group substitution positions)) are used. Also good. In the above mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm.

  If the content of Zr in the silver salt photothermographic dry imaging material of the present invention is 0.5 mg or less per mole of silver, there is no practical problem.

  It is preferable to contain a preservative (for example, benzoisothiazolinone sodium salt) in the aqueous dispersion.

  The compound represented by the general formula (N) in the present invention is preferably used in the range of 1 to 5000 mol%, more preferably 10 to 1000 mol%, still more preferably based on the photosensitive silver halide. 50 to 300 mol%.

(Organic fatty acid silver salt)
In the present invention, the organic silver salt is a reducible silver source, and is a silver salt of an organic acid or heteroorganic acid, particularly a long chain (C10-30, preferably 15-25) aliphatic carboxylic acid. And a silver salt of a nitrogen-containing heterocyclic compound. Organic or inorganic materials described in Research Disclosure (hereinafter simply referred to as RD) 17029 and 29963 such that the ligand has a value of 4.0 to 10.0 as the total stability constant for silver ions. Complexes are also preferred. Examples of these suitable silver salts include:

  Silver salts of organic acids (eg, gallic acid, succinic acid, behenic acid, stearic acid, arachidic acid, palmitic acid, lauric acid, etc., silver carboxyalkylthiourea salts (eg, 1- (3-carboxypropyl) thio) Urea, silver salts such as 1- (3-carboxypropyl) -3,3-dimethylthiourea), silver salts or complexes of polymer reaction products of aldehydes and hydroxy-substituted aromatic carboxylic acids (for example, aldehydes (formaldehyde , Acetaldehyde, butyraldehyde, etc.) and hydroxy-substituted acids (eg, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, etc., reaction product silver salts or complexes), thiones silver salts or complexes (eg, 3 -(2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione, 3-carboxymethyl Silver salts or complexes such as 4-thiazoline-2-thione), imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benz Complex or salt of nitrogen acid and silver selected from triazole, silver salt such as saccharin, 5-chlorosalicylaldoxime, or silver salt of mercaptides, among these, preferred silver salts include silver behenate and silver arachidate In the present invention, it is preferable to mix two or more organic silver salts in order to improve developability and form a silver image having a high density and a high contrast. It is preferable to prepare by mixing a silver ion solution with the above organic acid mixture.

  The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver. As described in Japanese Patent Application Laid-Open No. 9-127643, a normal mixing method, a reverse mixing method, and a simultaneous mixing method are used. A controlled double jet method or the like is preferably used.

  For example, an alkali metal salt (for example, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to prepare an organic acid alkali metal salt soap (for example, sodium behenate, sodium arachidate), and then a controlled double jet According to the method, the soap and silver nitrate are mixed to prepare organic silver salt crystals. At that time, silver halide grains may be mixed.

  The organic silver salt according to the present invention can be used in various shapes, but tabular grains are preferred.

  Particularly preferred are tabular organic silver salt particles having an aspect ratio of 3 or more, and the shape anisotropy of two substantially parallel faces (main planes) having the largest area is reduced in the photosensitive layer. In order to perform the filling, particles having an average needle-like ratio of the tabular organic silver salt particles measured from the main plane direction of 1.1 to 10 are preferable. A more preferable acicular ratio is 1.1 to 5.0.

  In the present invention, the term “tabular organic silver salt particles having an aspect ratio of 3 or more” means that the tabular organic silver salt particles occupy 50% or more of the total organic silver salt particles.

  Further, in the organic silver salt according to the present invention, it is preferable that tabular grains having an aspect ratio of 3 or more occupy 60% or more of the total number of organic silver salt grains, more preferably 70% or more (number). Preferably, it is 80% or more (number).

  The aspect ratio (hereinafter abbreviated as AR) is represented by the following formula.

AR = average particle diameter (μm) / average thickness (μm)
The aspect ratio of the tabular organic silver salt particles is preferably 3 to 20, and more preferably 3 to 10. The reason is that if the aspect ratio is too low, the organic silver salt particles are likely to be close-packed, and if the aspect ratio is too high, the organic silver salt particles are likely to overlap each other and are dispersed in a stuck state. The above range is preferable because light scattering or the like is likely to occur and the transparency of the photothermographic imaging material is lowered as a result.

  In order to obtain the above average particle diameter, the dispersed organic silver salt is diluted and dispersed on a grid with a carbon support film, and directly magnified 5000 times using a transmission electron microscope (JEOL Ltd., 2000FX type). Shoot at. The photographed negative is captured as a digital image by a scanner, and 300 or more particle sizes (equivalent circle diameter) are measured using appropriate image processing software, and the average particle size is calculated.

  Moreover, in order to obtain | require average thickness, it computed by the method using the transmission electron microscope (henceforth TEM) as shown below.

  First, the photosensitive layer coated on the support is attached to an appropriate holder with an adhesive, and an ultrathin slice having a thickness of 0.1 to 0.2 μm is produced using a diamond knife in a direction perpendicular to the support surface. To do. The ultra-thin slice was supported on a copper mesh, transferred onto a carbon film hydrophilized by glow discharge, and 5,000 to 40,000 times magnification using TEM while cooling to −130 ° C. or lower with liquid nitrogen. A bright field image is observed at, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like.

  At this time, it is preferable to appropriately select a portion where the section is not torn or slack as the field of view to be observed.

  As the carbon film, it is preferable to use a film supported by an organic film such as an extremely thin collodion or form bar, and more preferably, it is formed on a rock salt substrate and obtained by dissolving and removing the substrate. It is a carbon-only film obtained by removal by organic solvent and ion etching.

  The TEM acceleration voltage is preferably 80 to 400 kV, particularly preferably 80 to 200 kV.

  In addition, for details of electron microscope observation techniques and sample preparation techniques, see “The Japan Electron Microscopy Society Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Japan Electron Microscopy Society Kanto Branch / Electron Microscope Biological Samples” "Manufacturing method" (Maruzen) can be referred to respectively.

  A TEM image recorded on a suitable medium is preferably decomposed into at least 1024 × 1024 pixels, preferably 2048 × 2048 pixels, and subjected to image processing by a computer. In order to perform image processing, it is preferable to convert an analog image recorded on a film into a digital image by a scanner or the like, and to perform shedding correction, contrast / edge enhancement, or the like as necessary.

  Thereafter, a histogram is created, and a portion corresponding to organic silver is extracted by binarization processing.

  The thickness of the extracted organic silver salt particles is manually measured for 300 or more with appropriate software, and the average value is obtained.

  Moreover, the average value of the acicular ratio of tabular organic silver salt particles is obtained by the following method. First, the photosensitive layer containing tabular organic silver salt particles is swollen with an organic solvent capable of dissolving the photosensitive layer binder and peeled off from the support, and ultrasonic cleaning, centrifugation, and removal of the supernatant using the solvent are performed. Repeat 5 times. In addition, the said process is implemented under a safelight.

  Subsequently, the solution is diluted with methyl ethyl ketone (MEK) so that the solid content concentration of the organic silver salt is 0.01%, ultrasonically dispersed, and then dropped onto polyethylene terephthalate hydrophilized by glow discharge and dried.

  The film on which the particles are mounted is preferably used for observation after obliquely depositing Pt-C having a thickness of 3 nm with an electron beam from an angle of 30 ° with respect to the film surface in a vacuum deposition apparatus. The prepared sample was observed with a field emission scanning electron microscope (FE-SEM) at an acceleration voltage of 2 to 4 kV and a secondary electron image at a magnification of 5000 to 20000, and an image on an appropriate recording medium. Save.

  For the above processing, it is convenient to use an apparatus capable of AD-converting the image signal from the electron microscope main body and recording it directly as digital information on the memory. It can be used by converting it into a digital image and applying it as necessary, such as shading correction and contrast / edge enhancement.

  As the image processing procedure described above, first, a histogram is created, and a portion corresponding to organic silver salt particles having an aspect ratio of 3 or more is extracted by binarization processing. The aggregated particles are unavoidably cut by an appropriate algorithm or manual operation to extract the contour. Thereafter, the maximum length (MX LNG) and the minimum width (WIDTH) of each particle are measured for at least 1000 particles, and the acicular ratio is determined for each particle by the following formula.

  The maximum length of a particle is the maximum value when two points in the particle are connected by a straight line. Further, the minimum width of the particle means a value when the distance between the parallel lines becomes a minimum value when two parallel lines circumscribing the particle are drawn.

Needle-shaped ratio = (MX LNG) ÷ (WIDTH)
Then, the average value of the acicular ratio regarding all the measured particles is calculated. When performing the measurement according to the above procedure, it is preferable to sufficiently perform length correction (scale correction) per pixel and correction of two-dimensional distortion of the measurement system using a standard sample in advance.

  Uniform latex particles (DULP) marketed by US Dow Chemical Company are suitable as a standard sample, and polystyrene particles having a coefficient of variation of less than 10% with respect to a particle size of 0.1 to 0.3 μm are used. Specifically, a lot having a particle size of 0.212 μm and a standard deviation of 0.0029 μm is available.

  The details of the image processing technology can be referred to “Image Processing Application Technology (Industry Research Committee)” edited by Hiroshi Tanaka, and the image processing program or device is not particularly limited as long as the above operation is possible, but as an example Examples include Luzex-III manufactured by Nireco.

  The method for obtaining the organic silver salt particles having the above-mentioned shape is not particularly limited, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap is kept good. And optimizing the proportion of silver nitrate that reacts with soap.

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

  The media disperser can use a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill that is a medium stirring mill, an attritor, and other basket mills. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are collided at a high speed after being divided into a plurality of liquids, and a type in which thin orifices are passed.

Examples of the ceramic used for the ceramic beads used when dispersing the media 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), Si ₂ O—nH ₂ O, ticker silicon, yttrium stabilized zirconia, zirconia reinforced alumina and the like are preferable.

  Yttrium-stabilized zirconia and zirconia reinforced alumina (hereinafter, these ceramics containing zirconia are hereinafter abbreviated as zirconia) are particularly preferably used because of the low generation of impurities due to friction with beads and dispersers during dispersion.

  In the apparatus used when dispersing the flat organic silver salt particles, it is preferable to use ceramics such as zirconia, alumina, silicon nitride, boron nitride or diamond as the material of the member in contact with the organic silver salt particles, Among these, it is preferable to use zirconia.

  When the above dispersion is performed, the binder concentration is preferably added in an amount of 0.1 to 10% of the mass of the organic silver, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion through the main dispersion. As preferable operating conditions for this dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, 29.42 to 98.06 MPa, and the number of operations is preferably 2 times or more. Moreover, when using a media dispersion machine as a dispersion | distribution means, 6-13 m / sec of peripheral speed is mentioned as preferable conditions.

  Further, zirconia can be used for a part of the beads and members and can be mixed in the dispersed emulsion at the time of dispersion. This is preferably effective in terms of photographic performance. Zirconia fragments may be added later to the dispersed emulsion or may be added in advance during preliminary dispersion. Although it does not specifically limit as a specific method, For example, if MEK is circulated through the bead mill filled with zirconia beads, a high-concentration zirconia solution can be obtained. This may be added at a preferred concentration at a preferred time.

  In the photosensitive emulsion containing a photosensitive silver halide and an organic silver salt, it is preferable to contain 0.01 to 0.05 mg of zirconium per 1 g of silver, and a more preferable zirconium content is 0.01 to 0.00. 3 mg. Further, as a preferable form, fine particles having a diameter of 0.02 μm or less are preferable.

  The conditions for preparing the photosensitive emulsion having such characteristics are not particularly limited. However, the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap are favorable. Maintaining, optimizing the proportion of silver nitrate that reacts with soap, dispersing and dispersing with media dispersion or high-pressure homoeiser, the binder concentration is 0.1 to 10% by mass of the amount of organic silver salt In addition to the addition, the temperature from drying to the end of the main dispersion does not exceed 45 ° C., and the like, it is preferable to stir at a peripheral speed of 2.0 seconds or more using a dissolver during preparation.

The ratio of the projected area and the total projected area of the organic silver salt grains having a specific projected area value as described above is the same as described in the section for obtaining the average thickness of the tabular grains having an aspect ratio of 3 or more. Then, a portion corresponding to the organic silver salt is extracted by a method using TEM. At this time, the aggregated organic silver salt is treated as one particle, and the area of each particle is determined. Similarly, at least 1000, preferably obtains the area about 2,000 particles, each, A: 0.025 .mu.m less than ^{2, B: 0.025~0.2μm 2, C} : 0.2μm 2 or more 3 Classify into groups.

  In the silver salt photothermographic imaging material of the present invention, the total area of particles belonging to Group A was 70% or more of the measured area of all particles, and the total area of particles belonging to Group C was measured. What satisfies 10% or less of the area of all the particles is preferable.

  When performing the measurement according to the above procedure, it is preferable to sufficiently perform correction of the length per pixel (scale correction) and correction of the two-dimensional distortion of the measurement system in advance using a standard sample.

  The organic silver salt particles are preferably monodisperse particles, and the preferred monodispersity is 1 to 30%. By using monodisperse particles in this range, an image with a high density can be obtained.

  The monodispersion here is defined by the following formula.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100
The average particle diameter of the organic silver salt is preferably 0.01 to 0.2 μm, more preferably 0.02 to 0.15 μm. The average particle diameter (equivalent circle diameter) is an individual observed with an electron microscope. Represents the diameter of a circle having the same area as the particle image.

(Reducing agent)
The photothermographic material of the present invention preferably contains a reducing agent.

  Examples of suitable reducing agents are described in U.S. Pat. Nos. 3,770,448, 3,773,512, 3,593,863, and RDs 17029 and 29963. There is something. Aminohydroxycycloalkenone compounds (eg, 2-hydroxypiperidino-2-cyclohexenone); aminoreductones esters (eg, piperidinohexose reductone monoacetate) as precursors of reducing agents; N— Hydroxyurea derivatives (eg Np-methylphenyl-N-hydroxyurea); aldehyde or ketone hydrazones (eg anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (Eg hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone and (2,5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (eg benzenesulfhydroxam ); Sulfonamidoanilines (eg, 4- (N-methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (eg, 2-methyl-5- (1-phenyl-5-tetrazolylthio) hydroquinone); tetrahydro Quinoxalines (eg, 1,2,3,4-tetrahydroquinoxaline); amidoxins; azines (eg, a combination of aliphatic carboxylic acid arylhydrazides and ascorbic acid); a combination of polyhydroxybenzene and hydroxylamine; Hydroxanoic acids; Combinations of azines and sulfonamidophenols; α-Cyanophenylacetic acid derivatives; Combinations of bis-β-naphthol and 1,3-dihydroxybenzene derivatives; 5-Pyrazolones; Sulfonamides Enol reducing agent; 2-phenylindane-1,3-dione, etc .; Chroman; 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine); Bisphenols (For example, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol, 2,2-bis (4-hydroxy-3-methyl Phenyl) propane, 4,5-ethylidene-bis (2-t-butyl-6-methyl) phenol), UV-sensitive ascorbic acid derivatives and 3-pyrazolidones. Among these, particularly preferred reducing agents are hindered phenols.

(binder)
Water-soluble binders suitable for the silver salt photothermographic imaging materials of the present invention are transparent or translucent and generally colorless, natural polymers, synthetic polymers and copolymers, and other media forming films such as gelatin, gum arabic, Poly (vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, polyacrylic acid, polymethylmethacrylic acid, polyvinyl chloride, polymethacrylic acid, copoly (styrene-maleic anhydride) Acid), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinyl acetals (polyvinyl formal, polyvinyl butyral), polyesters, polyurethanes, phenoxy resins, polyvinyl chloride Emissions, polyepoxides, polycarbonates, polyvinyl acetate, cellulose esters, and polyamides.

  These may be hydrophilic or non-hydrophilic. Further, SBR latex, NBR latex and the like may be added.

  Preferred binders for the photosensitive layer of the photothermographic imaging material of the present invention are polyvinyl acetals, and a particularly preferred binder is polyvinyl butyral. In addition, in non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters having a higher glass transition temperature (Tg), particularly polymers such as triacetate cellulose and cellulose acetate butyrate. Is preferred. In addition, the said binder can be used in combination of 2 or more type as needed.

  Examples of the binder preferably used in the present invention include the following polyvinyl acetals.

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

The effective range can be easily determined by those skilled in the art. For example, when the photosensitive layer retains at least the organic silver salt, the ratio of the binder to the organic silver salt is preferably in the range of 15: 1 to 1: 2, particularly 8: 1 to 1: 1. That is, it is preferable that the binder of the photosensitive layer is a 1.5~6g / m ^2, more preferably from 1.7~5g / m ^2. 1.5 g / m ²
If it is less than 1, the density of the unexposed area will be greatly increased, and there is a case where it cannot be used.

(Water-soluble binder)
Water-soluble binders suitable for photothermographic imaging materials are transparent or translucent, generally colorless, natural polymer synthetic resins, 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, polyacrylic acid, polymethylmethacrylic acid, polyvinyl chloride, polymethacrylic acid, copoly (styrene-maleic anhydride), copoly (Styrene-acrylonitrile), copoly (styrene-butadiene), polyvinyl acetals (polyvinyl formal, polyvinyl butyral, etc.), polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, Riepokishido, polycarbonates, polyvinyl acetate, cellulose esters, and polyamides.

  In general, single or multiple photothermographic silver halides are provided in the form of hydrophilic photosensitive silver halide emulsions containing one or more peptizers (eg, gelatin). A typical concentration of silver halide in the formulation to be coated is 0.01 to 1 mole of photosensitive silver halide per mole of non-photosensitive source of reducible silver ions.

  Hydrophilic silver halide emulsions containing pepsiders can be made using conventional methods in the photographic art, including those described in Product Licensing Index, Vol. 92, December 1971. The photographic silver halide can be washed or unwashed as described and can be chemically sensitized as follows. The “hydrophilic photosensitive silver halide emulsion” is assumed to contain one or more peptizers that are compatible with an aqueous solvent.

  Useful peptizers include, but are not limited to, gelatin-based peptizers known in the photographic art such as phthalated and non-phthalated gelatin, gelatin hydrolyzed with acid or base, and poly (vinyl alcohol). Particularly preferred peptizers are cationic starches, which are described in US Pat. Nos. 5,604,085, 5,620,840, 5,667,955, and 5,733,718. ing. Such peptizers reduce fog and clearly improve the shelf life of raw films.

  The amount of peptizer in the hydrophilic silver halide emulsion is generally 5-40 g per mole of silver. A particularly effective concentration of peptizer is 9-15 grams per mole of silver.

  It is also preferred that a hydrophilic binder be present in the silver halide blend or emulsion. Useful water-soluble binders, including those conventionally used to prepare silver halide emulsions for photographic light-sensitive materials, may be the same as or different from the peptizer. Gelatins, polyacrylamides, polymethacrylates, poly (vinyl alcohol) and starches are preferred. Poly (vinyl alcohol) is a more preferred binder for aqueous silver halide emulsions.

  Preferred binders for the photosensitive layer of the silver salt photothermographic imaging material are polyvinyl acetals, and a particularly preferred binder is polyvinyl butyral. In addition, in a non-photosensitive layer such as an overcoat layer or an undercoat layer, particularly a protective layer or a backcoat layer, a cellulose ester having a higher softening temperature, particularly a polymer such as triacetyl cellylose or cellulose acetate butyrate. Is preferred. In addition, the said binder can be used in combination of 2 or more type as needed.

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

The effective range can be easily determined by one skilled in the art. For example, in the photosensitive layer, as an index for holding at least the organic silver salt, the ratio of the binder to the organic silver salt is preferably in the range of 15: 1 to 1: 2, particularly 8: 1 to 1: 1. That is, it is preferable that the binder of the photosensitive layer is a 1.5~6g / m ^2, more preferably from 1.7~5g / m ^2. If it is less than 1.5 g / m ² , the density of the unexposed area is significantly increased and may not be used.
(Crosslinking agent)
As the crosslinking agent, various crosslinking agents conventionally used for ordinary photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based compounds described in JP-A No. 50-96216 are used. , Sulfonic acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents may be used, and the following isocyanate-based compounds, silane compounds, epoxy-based compounds, and acid anhydrides are preferable. These compounds are described in detail in JP-A No. 2001-249428.

(Matting agent)
In the present invention, it is preferable to contain a matting agent on the photosensitive layer side, and it is preferable to add a matting agent to the surface of the photographic material in order to prevent scratches on the image after heat development.

  The matting agent is preferably contained in a mass ratio of 0.5 to 10% with respect to the total binder on the photosensitive layer side.

  The material of the matting agent used in the present invention may be either organic or inorganic. Examples of inorganic substances include silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, and alkaline earth metal described in British Patent No. 1,173,181. Alternatively, carbonates such as cadmium and zinc can be used as the matting agent. Organic substances include starch described in US Pat. No. 2,322,037 and the like, and starch derivatives described in Belgian Patent 625,451 and British Patent 981,198. Polyvinyl alcohol described in JP-B No. 44-3643, etc., polystyrene or polymethacrylate described in Swiss Patent No. 330,158, etc., polyacrylonitrile described in US Pat. No. 3,079,257, etc., US Pat. No. 3,022, An organic matting agent such as polycarbonate described in No. 169 or the like can be used.

  The shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is particularly preferably used.

  The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere, and the particle size of the matting agent in the present invention indicates the diameter converted into a sphere.

  The matting agent used in the present invention preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. Further, the coefficient of variation of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less.

  The variation coefficient of the grain size distribution here is expressed by the same formula as the variation coefficient of the silver particles.

  The matting agent can be contained in any layer constituting layer, but is preferably added to a constituent layer other than the photosensitive layer, and more preferably added to the outermost layer as viewed from the support.

  The method for adding the matting agent may be a method in which the matting agent is dispersed and applied in advance, or a method in which the matting agent is sprayed before the coating solution is applied and drying is completed may be used. . In addition, when a plurality of types of matting agents are added, both methods may be used in combination.

(Coloring agent)
A preferred color toning agent to which a color toning agent is preferably added to the photothermographic material of the present invention is disclosed in RD17029, and specific examples thereof include the following.

  Imides (such as phthalimide); Cyclic imides, pyrazolin-5-ones and quinazolines (succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline, 2,4-thiazolidinedione, etc. ); Naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt); mercaptans (eg, 3-mercapto-1,2,4-triazole) N- (aminomethyl) aryl dicarboximides (eg, N-dimethylaminomethyl) phthalimide); combinations of blocked pyrazoles, isothiuronium derivatives and certain photobleaching agents (eg, N, N-hexamethylene (1-carbamoyl-3,5-di Tilpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) -benzothiazole); merocyanine dye (3-ethyl-5 -[(3-ethyl-2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene] -2-thio-2,4-oxazolidinedione, etc.); phthalazinone, phthalazinone derivatives or derivatives thereof Metal salts (such as 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxytarazinone and 2,3-dihydro-1,4-phthalazinedione); combinations of phthalazinone and sulfin derivatives (For example, 6-chlorophthalazine + sodium benzenesulfinate or 8-methyl Tarazinone + sodium p-trisulfonate, etc.); combination of phthalazine + phthalic acid, phthalazine (including adducts of phthalazine) and maleic anhydride and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene derivative and anhydrous In combination with at least one compound selected from phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride; quinazolinedione, benzoxazine, naphthoxazine derivatives; benzoxazine-2,4 -Diones (for example, 1,3-benzoxazine-2,4-dione, etc.); pyrimidines and asymmetric-triazines (for example, 2,4-dihydroxypyrimidine, etc.) and tetraazapentalene derivatives (for example, 3 , 6-Dimercapto-1,4-diphenyl-1H , 4H-2,3a, 5,6a-tetraazapentalene, etc.), etc., and particularly preferred toning agents are phthalazone or phthalazine.

(Layer structure)
The silver salt photothermographic dry imaging material of the present invention has at least one photosensitive layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. In order to control the amount of light transmitted to the photosensitive layer or the wavelength distribution, a filter layer may be formed on the same side or the opposite side of the photosensitive layer, or a dye or pigment may be directly contained in the photosensitive layer.

  The photosensitive layer may be composed of a plurality of layers, or may have a different sensitivity for adjusting the gradation, for example, a high sensitivity layer / low sensitivity layer or a low sensitivity layer / high sensitivity layer.

  Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other forming layers.

  In the silver salt photothermographic dry imaging material of the present invention, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid, and the like may be used.

(Coating technology)
The silver salt photothermographic dry imaging material of the present invention is formed by preparing a coating solution in which the material of each constituent layer described above is dissolved or dispersed in a solvent, coating a plurality of these coating solutions simultaneously, and then performing a heat treatment. It is preferable.

  Here, “multiple simultaneous multi-layer coating” means that a coating solution of each layer configuration (for example, photosensitive layer, protective layer) is prepared, and when coating this onto a support, each layer is individually coated and dried. Instead, it means that various constituent layers can be formed in such a state that simultaneous multilayer coating and drying can be performed. That is, the upper layer is provided before the total remaining solvent amount in the lower layer becomes 70% by mass or less.

  There are no particular restrictions on the method of applying multiple layers simultaneously for each constituent layer, and for example, a known method such as a bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, or extrusion coating method may be used. Can do. Of these, a pre-weighing type coating method called an extrusion coating method is more preferable. Since the extrusion coating method does not volatilize on the slide surface unlike the slide coating method, it is suitable for precision coating and organic solvent coating. This coating method has been described on the side having the photosensitive layer, but the same applies to the case of coating with undercoating when providing back coating.

(Exposure conditions)
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 color sensitivity imparted to the material. For example, if the material can be felt as infrared light, it can be applied to any light source in the infrared light range, but the laser power is high power, the material can be made transparent, etc. From this point, an infrared semiconductor laser (780 nm to 820 nm) or a blue laser (near 400 nm) is more preferably used.

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

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

  The beam spot diameter on the exposed surface when the laser beam is scanned onto the silver salt photothermographic dry imaging material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable in that the smaller the spot diameter, the smaller the angle of deviation of the laser incident angle from the vertical.

  The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as generation of interference fringe-like unevenness.

  As a second method, the exposure is preferably performed using a laser scanning exposure machine that emits scanning laser light that is a vertical multi. Compared with a longitudinal single mode scanning laser beam, image quality degradation such as occurrence of interference fringe-like unevenness is reduced. In order to make it vertically multi-ply, methods such as using return light by multiplexing and applying high-frequency superposition are preferable.

  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.

  As the third aspect, it is also preferable to form an image by optical scanning exposure using two or more lasers.

  As such an image recording method using a plurality of lasers, it is used in an image writing means of a laser printer or a digital copying machine which writes an image line by line in one scan in response to a demand for high resolution and high speed. For example, Japanese Patent Laid-Open No. 60-166916 is known. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror and imaged on a photosensitive member via an fθ lens or the like. In principle, the laser scanning optical device is the same as a laser imager or the like. is there.

  The image formation of laser light on the photoconductor in the image writing means of laser printers and digital copying machines is shifted by one line from the image formation position of one laser light for the purpose of writing multiple lines one by one in one scan. The next laser beam is imaged. Specifically, the two light beams are close to each other on the image plane in the sub-scanning direction with an interval of the order of several tens of μm, and the printing density is 400 dpi (dpi is the number of dots per inch, that is, 2.54 cm). The sub-scanning direction pitch of the two beams is 63.5 μm, and 42.3 μm at 600 dpi.

  Unlike such a method of shifting the resolution distribution in the sub-scanning direction, in the present invention, it is preferable to form an image by changing the incident angle with two or more lasers at the same place and condensing on the exposure surface. At this time, when the exposure energy on the exposure surface when writing with one ordinary laser (wavelength λ nm) is En, the range is 0.9 × E ≦ En × N ≦ 1.1 × E. preferable.

  By doing so, energy is secured on the exposure surface, but the reflection of each laser beam to the image forming layer is reduced because the laser exposure energy is low, and the occurrence of interference fringes is suppressed.

  In the above description, a plurality of lasers having the same wavelength λ are used. However, lasers having different wavelengths may be used. In this case, it is preferable that the range is (λ−30) <λ1, λ2,... Λn ≦ (λ + 30) with respect to λnm.

In the image recording methods of the first, second, and third modes described above, solid lasers such as ruby lasers, YAG lasers, and glass lasers; HeNe lasers that are commonly known as lasers used for scanning exposure , Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, HeCd laser, N ₂ laser, excimer laser and other gas lasers; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb Semiconductor lasers such as lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner, but among these, semiconductor lasers with a wavelength of 600 to 1200 nm are used due to maintenance and light source size problems. preferable.

  In addition, in a laser used in a laser imager or a laser image setter, the beam spot diameter on the material exposure surface when scanned with a silver salt photothermographic dry imaging material is generally 5 to 75 μm as a minor axis diameter, The major axis 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 material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the material.

(Development conditions)
In the silver salt photothermographic dry imaging material of the present invention, development conditions vary depending on the equipment, apparatus, or means used, but typically the imagewise exposed material is heated at a suitable high temperature. With that.

  The latent image obtained after the exposure is subjected to rapid processing at a moderately high temperature (for example, about 80 to 150 ° C., preferably 100 to 130 ° C.) for a sufficient time (in the present invention, a speed of 5 seconds to about 20 seconds). Development is carried out by heating.

  If the heating temperature is less than 80 ° C., sufficient image density cannot be obtained in a short time, and if the heating temperature exceeds 150 ° C., the binder melts, and transfer to a roller, not only the image itself, It also adversely affects the developing machine. By heating, a silver image is generated by an oxidation-reduction reaction with an aliphatic carboxylic acid silver salt (which functions as an oxidizing agent) reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside.

  The heating device, apparatus, and means may be performed by a typical heating means as a heat generator using a hot plate, iron, hot roller, carbon or white titanium, and more preferably silver salt photothermal heat provided with a protective layer. In the case of photographic dry imaging material, it is preferable that the surface having the protective layer is brought into contact with the heating means for heat treatment in terms of uniform heating, heat efficiency, workability, and the like. It is preferable to carry out the development while carrying out heat treatment while contacting the film.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In the examples, “%” represents “mass%”.
Example 1
<Preparation of photosensitive silver halide emulsion A>
(A1)
66.2 g of phenylcarbamoylated gelatin
Compound A (* 1) (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water (B1)
0.67 mol / liter silver nitrate aqueous solution 26.35 ml
(C1)
62.52 g of potassium bromide
Potassium iodide 1.78g
Finish to 660ml with water (D1)
Potassium bromide 185.82g
Potassium iodide 5.29g
0.93ml potassium hexachloroiridium (IV) (1% aqueous solution)
Finish to 1982ml with water (E1)
0.4 mol / liter potassium bromide aqueous solution The following silver potential control amount (F1)
Potassium hydroxide 0.71g
Finish to 20ml with water (G1)
56% acetic acid aqueous solution 18.0 ml
(H1)
Anhydrous sodium carbonate 1.72 g
Finish to 151 ml with water * 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 = 5-7)
<Preparation of photosensitive silver halide emulsion Em-A (comparative)>
Using a mixing stirrer shown in Japanese Patent Publication No. 58-58288, while controlling 1/4 of the solution (B1) and the total amount of the solution (C1) to 32 ° C. and pAg 8.09 in the solution (A1). Then, nucleation was performed by adding 4 minutes and 45 seconds by the simultaneous mixing method. After 7 minutes, 3/4 amount of the solution (B1) and the total amount of the solution (D1) were added by a simultaneous mixing method over 14 minutes and 15 seconds. After stirring for 5 minutes, the temperature was raised to 40 ° C., the whole amount of the solution (G1) was added, and the silver halide emulsion was precipitated. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 liters of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 liters of water was further added, and after stirring, the silver halide emulsion was precipitated. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution (H1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount of silver was 1161 g per mole of silver to obtain a photosensitive silver halide emulsion Em-A. This emulsion has a monodisperse cubic silver iodobromide grain having an average grain size of 43 nm (equivalent circle diameter) grain size variation coefficient of 16% and a [100] face ratio of 89% (the silver halide grain has an AgI content of 2.0). Mol%).

<Preparation of photosensitive silver halide emulsion Em-B (present invention)>
In the same manner as in the photosensitive silver halide emulsion Em-A, the temperature was set to 32 ° C., and the addition amount of potassium hexachloroiridium (IV) was reduced to 1/3. The solid dispersed chalcogen releasing compound C-1-2 was added to a 1 × 10 ⁻⁴ mol / Ag mol solution (A1). The other steps were the same as the preparation of the comparative light-sensitive silver halide emulsion Em-A to obtain the light-sensitive silver halide emulsion Em-B of the present invention.

  This emulsion was monodisperse cubic silver iodobromide grains having an average grain size of 41 nm (equivalent circle diameter), a grain size variation coefficient of 12%, and a [100] face ratio of 94%.

<Preparation of photosensitive silver halide emulsion Em-C (invention)>
Nucleation was carried out at a temperature of 32 ° C. in the same manner as for the photosensitive silver halide emulsion Em-B. After 3 minutes, 1 × 10 ⁻⁴ mol / Ag mol of solid dispersion chalcogen releasing compound C-1-2 was added. After 7 minutes, solution (F1) was added. After 20 minutes, the solution (B1) and the solution (D1) were added by a simultaneous mixing method over 14 minutes and 15 seconds. Further, KBr was added at the end to make EAg = 0 mV, and then 0.1 mol / Ag mol of hydrogen peroxide was added. The other steps were the same as the preparation of the comparative light-sensitive silver halide emulsion Em-A to obtain the light-sensitive silver halide emulsion Em-C of the present invention. This emulsion was a monodisperse cubic silver iodobromide grain having an average grain size of 44 nm (equivalent circle diameter), a grain size variation coefficient of 12%, and a [100] face ratio of 94%.

<Preparation of photosensitive silver halide emulsion Em-D (invention)>
The light-sensitive silver halide emulsion Em-B was prepared in the same manner, except that the temperature was set to 40 ° C. and the iodine content of the (C1) solution was changed from 2 mol% to 20 mol%. A silver halide emulsion Em-D was obtained. The emulsion had monodisperse cubic silver iodobromide grains having an average grain size of 45 nm (equivalent circle diameter) and a grain size variation coefficient of 11% and a [100] face ratio of 91%.

(Chemical sensitization)
<Preparation of stabilizer solution>
A stabilizer solution was prepared by dissolving 1.0 g of Dye Stabilizer-1 in 0.31 g of potassium acetate in 4.97 g of methanol.

<Preparation and addition of infrared sensitizing dye solution>
As shown in Table 2, General Formulas (1) to (3) and (D), 1,488 g of 2-chlorobenzoic acid, 2.779 g of Dye Stabilizer-2 and 365 mg of Dye Stabilizer-3 were 31 Infrared sensitizing dye solution was prepared by dissolving in 3 ml of methanol in the dark.

The above photosensitive silver halide emulsions Em-B, C and D were each kept at a constant temperature of 47 ° C., the pH of each emulsion was 6.5, and 1 × 10 ⁻⁴ as triphenylphosphine sulfide as a solid dispersion. 30 minutes after addition of mol / Ag mol, 1% Stabilizer-A methanol solution was added so that Stabilizer-A was equivalent to 3 × 10 ⁻⁴ mol / Ag mol. After 10 minutes, the infrared sensitizing dye solution shown in Table 2 was added and aged for 1 hour 30 minutes.

  Thereafter, the pH was adjusted to 5.8, and as shown in Table 2, using the silver halide emulsions Em-B, C, D, an infrared photosensitive dye (infrared photosensitive dye, general formula (1) to ( Spectral sensitized silver halide emulsions 1 to 16 were obtained by changing 3) and (D)).

(Preparation of powdered organic silver salt)
In 5470 ml of pure water, 52.3 g of behenic acid, 27.1 g of arachidic acid, 17.4 g of stearic acid and 0.9 g of palmitic acid were dissolved at 80 ° C. Next, 270.1 ml of a 1.5 mol / liter sodium hydroxide aqueous solution was added while stirring at high speed, 6.9 ml of concentrated nitric acid was added, and then cooled to 55 ° C. to obtain an organic acid sodium solution. While maintaining the temperature of the organic acid sodium solution at 55 ° C., 380.3 ml of 1 mol / liter silver nitrate solution was added over 2 minutes to form an organic silver salt, and then the conductivity of the filtrate was reduced to 2 μS / cm. After repeating washing with deionized water and filtration until it was, centrifugal dehydration was performed, followed by heat drying until there was no decrease in mass.

(Preparation of organic fatty acid silver salt dispersion)
14.57 g of polyvinyl butyral powder (Monsant: Butar B-79) was dissolved in 1457 g of methyl ethyl ketone (MEK), and while stirring with a dissolver type homogenizer, 500 g of the powdered organic silver salt was gradually added and mixed well. . Thereafter, the dispersion was carried out at a peripheral speed of 13 m and a residence time in the mill of 0.5 minutes using a media type dispersing machine (made by Gettzmann) filled with 80% 1 mm-diameter zirconium beads (made by Toray Industries, Inc.). A salt dispersion was prepared.

<Preparation of photosensitive silver halide methyl ethyl ketone (MEK) emulsions 1-16>
(Preparation of polymer B solution)
A 0.3 liter four-necked separable flask was equipped with a dropping device, a thermometer, a nitrogen gas introduction tube, a stirring device, and a reflux condenser, charged with 20 g of MEK, and heated to the temperature shown in Table 1. Further, a monomer (unit g) having a composition ratio shown in Table 1 was weighed, and a solution in which 2 g of N, N′-azobisisovaleronitrile was further added to the monomer was dropped into the flask over 2 hours. The reaction was carried out at temperature for 5 hours. Thereafter, 80 g of MEK was added and cooled to obtain a polymer B solution containing 50% by mass of the polymer. The molecular weight was determined by GPC as a weight average molecular weight in terms of polystyrene.

PME-400: Bremer PME-400
Methacrylate PSE-400 having — (EO) _m —CH ₃ (m≈9): Bremer PSE-400
-(EO) _m -C ₁₈ H ₃₇ (m≈9) methacrylate
Here, (EO) is an ethyleneoxy group As described above, Aam: acrylamide DAAM: diacetone acrylamide (manufactured by Kyowa Hakko Co., Ltd.) manufactured by NOF Corporation
(Preparation of spectrally sensitized photosensitive silver halide methyl ethyl ketone emulsions 1-16)
20 g of the polymer B solution was made up to 60 g with methanol and stirred at 40 ° C. for 30 minutes. Thereto, 59.2 g of each of the spectrally sensitized silver halide emulsions 1-16 dissolved at 40 ° C. was added and stirred for another 30 minutes, so that the silver halide emulsions 1-16 were equimolar with each of the silver halide emulsions 1-16. Then, the mixture was diluted 2 times with MEK, and water was removed by vacuum distillation using a rotary evaporator. Thus, photosensitive silver halide methyl ethyl ketone emulsions 1 to 16 dispersed in the polymer B / MEK solution were prepared, respectively.

(Coating on the photosensitive layer side)
<< Preparation of each additive liquid >>
<Preparation of additive solution a>
11.9 g of reducing agent-A; 145 g of reducing agent-B was dissolved in 89 g of 4-methylphthalic acid, and 0.045 g of infrared dye 1 was dissolved in 120 g of MEK to obtain additive liquid a.
<Preparation of additive liquid b>
3.56 g of antifoggant-2 and the compounds and amounts shown in Table 2 represented by the general formula (N) were dissolved in 40.9 g of MEK to obtain an additive solution b.

<Preparation of photosensitive layer coating solutions 1 to 16>
While stirring 50 g of the organic fatty acid silver salt dispersion and 15.11 g of MEK at 18 ° C., a methanol solution of antifoggant-1 (3.2 × 10 ⁻³ mol / Ag mol) was added and stirred for 30 minutes. After adding 12.45 g of a polyvinyl acetal resin (compound P-1, Tg = 75 ° C.) as a binder resin and stirring, 1.1 g of tetrachlorophthalic acid (13% MEK solution) 1.1 g Desmodur N3300 (Movey) (Product: Aliphatic isocyanate) 22% MEK solution 2.23 g, additive liquid a21.2 g, additive liquid b 4.27 g was added, and as shown in Table 2, the photosensitivity dispersed in the polymer B / MEK solution 7.2 g of each of silver halide methyl ethyl ketone emulsions 1 to 16 was added. The photosensitive layer coating solutions 1 to 16 were obtained by stirring.

<Surface protective layer coating solution>
While stirring MEK865g, 96 g of cellulose acetate butyrate (manufactured by Eastman Chemica, CAB171-15), 4.5 g of polymethylmethacrylic acid (Rohm & Haas, Paraloid A-21), 1.5 g of benzotriazole, F 1.0 g of a surfactant (Asahi Glass Co., Ltd., Surflon KH40) was added and dissolved. Next, 30 g of the matting agent dispersion was added and stirred, and Compound O was added so as to be 0.045 g / m ² to prepare a surface protective layer coating solution.

<Preparation of matting agent dispersion>
Dissolve 7.5 g of cellulose acetate butyrate (Eastman Chemical: CAB171-15) in 42.5 g of MEK, add 5 g of calcium carbonate (Speciality Mineral: Super-Pflex200) to it, and use a dissolver type homogenizer. Dispersion was performed at 8000 rpm for 30 minutes to obtain a matting agent dispersion.

<Preparation of back surface coating solution>
While stirring MEK830 g, 84.2 g of cellulose acetate (manufactured by Eastman Chemical: CAB381-20) and 4.5 g of polyester resin (bothic, Vitelpr 2200b) were added and dissolved. Infrared dye 1 is added to the dissolved solution so that the absorbance (abs) of the absorption maximum of infrared dye 1 in the coating sample on the back surface is 0.3, and further the fluorine-based interface dissolved in 43.2 g of methanol 4.5 g of an activator (Surflon KH40 manufactured by Asahi Glass Co., Ltd.) and 2.3 g of a fluorosurfactant (manufactured by Dainippon Ink Co., Ltd., Megafax 120K) were added, and the mixture was sufficiently stirred until dissolved. .

  Finally, 75 g of silica dispersed in a dissolver type homogenizer at a concentration of 1% by mass (Siloid 64 × 6000 manufactured by WR Grace) was added and stirred to prepare a back surface coating solution.

<Production of support>
Corona discharge treatment of 0.15 kV · A · min / m ² was performed on both sides of a blue-colored polyethylene terephthalate film base (thickness: 175 μm) having a concentration of 0.170. On one surface thereof, an undercoat layer a was applied using the following undercoat coating solution A so that the dry film thickness was 0.2 μm. Furthermore, the undercoat layer B was coated on the other surface using the following undercoat coating solution B so that the dry film thickness was 0.1 μm. Thereafter, heat treatment was performed at 130 ° C. for 15 minutes in a heat treatment type oven having a film transport device composed of a plurality of roll groups.

<Preparation of undercoat coating liquid A>
270 g of butyl acrylate / t butyl acrylate / styrene / 2-hydroxyethyl acrylate (30/20/25/25% ratio) copolymer latex liquid (solid content 30%), 0.6 g of surfactant (UL-1) And 0.5 g of methylcellulose were mixed. Further, 1.3 g of silica particles (manufactured by Fuji Syria Co., Ltd .: Psyroid 350) was added to 100 g of water, and the dispersion was subjected to a dispersion treatment for 30 minutes with an ultrasonic disperser (manufactured by AKEX Corporation: Ultrasonic Generator, frequency 25 kHz, 600 W). Finally, it was made up to 1000 ml with water to obtain a subbing coating solution A.

<Preparation of undercoat coating solution B>
37.5 g of the following colloidal tin oxide dispersion, copolymer latex liquid of butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate (20/30/25/25% ratio) (solid content 30%) 3 0.7 g, 14.8 g of copolymer latex liquid (solid content 30%) of butyl acrylate / styrene / glycidyl methacrylate (40/20/40% ratio) and 0.1 g of surfactant (UL-1) are mixed, The undercoating solution B was made up to 1000 ml with water.

<Preparation of colloidal tin oxide dispersion>
A homogeneous solution was prepared by dissolving 65 g of stannic chloride hydrate in 2000 ml of a water / ethanol mixed solution. Subsequently, this was boiled and the coprecipitate was obtained. The generated precipitate was taken out by decantation and washed several times with distilled water. Silver nitrate was dropped into distilled water from which the precipitate was washed, and after confirming that there was no reaction with chlorine ions, distilled water was added to the washed precipitate to make a total volume of 2000 ml. Furthermore, 40 ml of 30% aqueous ammonia was added, the aqueous solution was heated and concentrated to a volume of 470 ml, to prepare a colloidal tin oxide dispersion.

(Preparation of silver salt photothermographic dry imaging material sample)
A silver salt photothermographic dry imaging material was prepared by applying and drying the photosensitive layer surface side and the back layer surface side on both surfaces of the undercoated support in the combination shown in Table 2.

<Coating on the photosensitive layer side>
Using each of the prepared photosensitive layer coating liquid and surface protective layer coating liquid, a photothermographic dry imaging material was sampled by simultaneously coating the photosensitive layer and the surface protective layer from the support side using an extrusion coater. 1-16) were produced. The applied silver amount was 1.17 g / m ² , and the drying was performed for 5 minutes using a drying air having a temperature of 80 ° C. and a dew point temperature of 10 ° C. The surface protective layer was formed to have a dry film thickness of 1.5 μm.

<Application on the back side>
The prepared back surface side coating solution was applied and dried using an extrusion coater such that the dry film thickness was 3 μm. The drying temperature was 100 ° C., and drying was performed for 5 minutes using a drying air having a dew point temperature of 10 ° C.

  Table 2 shows the details of the configuration of the samples (samples 1 to 16) of the photothermographic dry imaging material produced as described above.

  Infrared photosensitive dyes IR-Dye-1, CCpd-1, and CCpd-2 used as comparative compounds in the table are shown below.

(Evaluation of characteristic values of photothermographic dry imaging materials-1)
<Measurement of Dmin, Dmax and sensitivity>
After processing each sample into a half-cut size, using a laser imager Drypro 752 manufactured by Konica Corporation, while developing a part of the sample, a part of the sample that has already been exposed is started to be developed. Remodeled. Exposure was imagewise exposure with a semiconductor laser at 785 nm. In the exposure, the angle between the exposure surface of the sample and the exposure laser beam was set to 80 degrees. Moreover, in order to match the exposure amount, evaluation was performed under conditions A and B.
Exposure condition A: transported at a laser intensity of 16 mW at 30.64 mm / sec, exposure condition B: transported at a laser intensity of 30 mW at 57.45 mm / sec. The high frequency superposition was output in the vertical multimode.

The heat development processing was performed uniformly using a heat drum, and the heat development processing conditions were 123 ° C. and 10 seconds. The density of the heat-development-treated sample thus obtained was measured with an optical densitometer PD-82 (manufactured by Konica Corporation), and a characteristic curve consisting of density D and exposure amount Log (1 / E) was created. )), Sensitivity, gradation (γ), and maximum density (Dmax) were measured. The sensitivity was defined as the logarithm of the reciprocal of the exposure amount giving a density 1.0 higher than the minimum density. Among these, the minimum density (Dmin) = fog density, sensitivity, and high illuminance sensitivity difference are shown in Table 3. The result is a comparative sample No. Indicated by a relative value with 1 being 100,
High illumination sensitivity difference = (exposure condition B sensitivity)-(exposure condition A sensitivity)
It was.

<Evaluation of storage stability>
The prepared sample was stored in a light-shielding container at 40 ° C. and 55% RH for 30 days, and this was subjected to forced deterioration treatment. For comparison, the same sample was stored in a light-shielding container at 25 ° C. and 55% RH for 7 days, and this was used as a reference treatment. These samples are exposed and heat-developed in the same manner as described above, the minimum density (fogging density) is measured in the same way, the increase in fog density (ΔDmin) is calculated by the following formula, and this is stored and stabilized. The value was expressed as a relative value with the value of Sample 1 as 100, as a measure of sex (raw storage stability).

ΔDmin = (fogging concentration of forced deterioration treated sample) − (fogging concentration of reference treated sample)
<Evaluation of image light resistance>
The optical density of the minimum density part (Dmin part) before and after leaving each sample heat-development-processed by said method indoors at 37 degreeC and 55% RH on a light source stand for 7 days under a fluorescent lamp is further set. According to the following formula, the variation (ΔDmin2) of the minimum density (Dnin) was determined, and this was used as a measure of light resistance and displayed as a relative value with that of Sample 1 as 100.

ΔDmin2- (Dmin after fluorescent lamp exposure)-(Dmin before fluorescent lamp exposure)
In addition, the temperature on the used light source stand was 45 degreeC and 8000 Lux. The results are shown as relative values with Sample 1 as the reference 100.

<Evaluation of silver tone>
The silver image created with the reference processed sample was visually evaluated, and the silver color tone was determined according to the following criteria.

  (Double-circle): It is the optimal silver tone at the time of visual diagnosis.

  ◯: Silver tone that does not hinder the visual diagnosis.

  X: The eyes are easily tired during visual diagnosis and have a silvery color that is difficult to diagnose.

  These measurement results are summarized in Table 3.

  As is apparent from Table 3, each sample of the present invention has low fog and high sensitivity, and is excellent in illuminance failure and light resistance. Moreover, it turned out that it is excellent also in raw storage stability and silver tone. In addition, the gradation (γ) of the sample of the present invention was all in the range of 2.5 to 5.0, and was suitable as a medical photosensitive material.

Claims (7)

In a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide particles on a support, a silver salt photothermographic dry imaging material having a silver ion reducing agent, a binder and a crosslinking agent, the photosensitivity The silver halide grains are surface latent image type grains before heat development, change to internal latent image type grains after heat development, and contain at least one compound represented by the following general formula (1) A silver salt photothermographic dry imaging material, characterized by comprising:

[Wherein R ₁ represents an aliphatic group, T ₁ represents an alkylene group, A ₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₁ represents a tertiary group. An amino group and a quaternary ammonium group are represented. Z ₁ and Z ₂ each represent a group of nonmetallic atoms necessary to form a 5-membered or 6-membered nitrogen-containing heterocycle, L _{1 to} L ₅ each represent the same or different methine groups, and M ₁ represents Represents an ion having a charge necessary to neutralize the charge of the molecule, r1 represents a number necessary to neutralize the charge of the whole molecule, l1 and q1 each represents 0 or 1, and m1 represents 1 or 2 is represented. ] The silver salt photothermographic dry imaging material according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein R ₁₁ represents an aliphatic group, T ₁₁ represents an alkylene group, A ₁₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₁₁ represents a tertiary group. Represents an amino group or a quaternary ammonium group. Z ₁₁ and Z ₁₂ each represent a group of non-metallic atoms necessary to form a 5-membered nitrogen-containing heterocycle, L _{11 to} L ₁₇ each represent the same or different methine groups, and M ₁₁ represents molecular charge. Represents an ion having a charge necessary to neutralize, r11 represents a number necessary to neutralize the charge of the whole molecule, and q11 represents 0 or 1. ] The silver salt photothermographic dry imaging material according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (3).

[Wherein R ₂₁ represents an aliphatic group, T ₂₁ represents an alkylene group, A ₂₁ represents an arylene group, an O-arylene group, an S-arylene group, an O-alkylene group or an S-alkylene group, and Q ₂₁ represents a tertiary group. Represents an amino group or a quaternary ammonium group. Z ₂₁ represents a nonmetallic atom group necessary for forming a 5-membered or 6-membered condensed ring, and X ₂₁ represents an oxygen atom, a sulfur atom or a selenium atom. Each V ₂₁ and V ₂₂ represents a hydrogen atom, an aryl group, a heterocyclic group, represents a thioether group or a sulfinyl group, never V ₂₁ and V ₂₂ are hydrogen atoms at the same time, M ₂₁ medium-charged molecules This represents an ion having a charge necessary for summation, r21 represents a number necessary for neutralizing the charge of the whole molecule, and q21 represents 0 or 1. ] In a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide particles on a support, a silver salt photothermographic dry imaging material having a silver ion reducing agent, a binder and a crosslinking agent, the photosensitivity The silver halide grains are surface latent image type grains before heat development, change to internal latent image type grains after heat development, and at least one compound represented by the following general formula (D) The silver salt photothermographic dry imaging material according to claim 1, comprising a layer containing a combination of at least one compound represented by the general formula (1).

[Wherein, R ₃₁ and R ₃₂ each independently represents an aliphatic group, Z ₃₁ represents a nonmetallic atom group necessary for forming a 5-membered or 6-membered condensed ring, X ₃₁ represents an oxygen atom, Represents a sulfur atom or a selenium atom. Each V ₃₁ and V ₃₂ represents a hydrogen atom, an aryl group, a heterocyclic group, represents a thioether group or a sulfinyl group, never V ₃₁ and V ₃₂ are hydrogen atoms at the same time, M ₃₁ medium-charged molecules It represents an ion having a charge necessary for summation, and r31 represents a number necessary for neutralizing the charge of the whole molecule. ] In a silver halide photothermographic dry imaging material having a photosensitive emulsion containing non-photosensitive aliphatic carboxylic acid silver salt particles and photosensitive silver halide grains on a support, a silver ion reducing agent, a binder and a crosslinking agent, the following general formula It has a layer containing at least 1 sort (s) of the compound represented by (N), The silver salt photothermographic dry imaging material of any one of Claims 1-4 characterized by the above-mentioned.

[Wherein, R ⁴¹ , R ⁴² , R ⁴³ and R ⁴⁴ each independently represent a hydrogen atom or a substituent, and R ⁴¹ , R ⁴² , R ⁴³ and R ⁴⁴ are bonded to each other to form a saturated or unsaturated group. A ring may be formed. ] The silver salt photothermographic dry imaging material according to any one of claims 1 to 5, wherein the photosensitive silver halide grains are not mixed when the non-photosensitive aliphatic carboxylic acid silver salt grains are formed. Silver salt photothermographic dry imaging material. An image forming method comprising: exposing the silver salt photothermographic dry imaging material according to any one of claims 1 to 6 to heat and developing at 80 to 150 ° C for 5 to 20 seconds.