JP2000072778A - Production of organic silver dispersion and heat developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an organic silver dispersion improved in dispersibility of an organic silver salt by cooling a raw material solution containing an organic silver salt and dispersing the organic silver salt and obtain a heat developable photosensitive material reduced in fogging by using the organic silver dispersion. SOLUTION: In this method for producing an organic silver dispersion by applying >=580 kgf/cm2 pressure to a raw material solution comprising at least organic silver salt and a solvent, when the temperature before disperse of the raw material solution is controlled to -95 deg.C to 35 deg.C and the pressure is A kgf/cm2 and the temperature before disperse of the raw material solution is B deg.C, the following formula is satisfied: 50>2A/100+B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material, and more particularly, to a method for producing an organic silver salt dispersion used therein.

[0002]

2. Description of the Related Art In recent years, in the medical field, X-ray CT, MR
As a means for outputting a diagnostic image such as I, a method has been adopted in which a photosensitive material is scanned with a laser beam and exposed to form an image. However, these photosensitive materials have been subjected to wet development processing after imagewise exposure by scanning with a laser beam and subjected to diagnosis.

In wet processing of photosensitive materials, waste liquid is a problem in terms of environmental protection. In recent years, it has been strongly desired to reduce the amount of processing waste liquid from the viewpoint of space saving.

Therefore, there has been a demand for a technique relating to a photothermographic material capable of efficiently exposing with a laser imager and forming a high-resolution and clear black image.

As this technique, for example, US Pat.
Nos. 152,904, 3,487,075 and D.I. "Dry Silver Photographic" by Morgan
Materials) "(Handbook of
Imaging Materials, Marcel
Dekker, Inc. 48, 1991), a photothermographic material containing an organic silver salt, photosensitive silver halide grains and a reducing agent on a support is known. Further, a heat-developable material which does not contain photosensitive silver halide grains and forms an image by thermal energy is widely known.

An organic silver salt is an essential component of the above-mentioned photothermographic material or photothermographic material, and its production method is described in JP-A-8-15808 and JP-A-8-137044.
No. 9-114036, U.S. Pat. No. 5,434,043
And the like. For example, a high-pressure homogenizer has been used for dispersing an organic silver salt. However, even when the dispersion conditions described in the above documents are used, there are problems such as low dispersion efficiency of the organic silver salt. In addition, since all of the dispersion methods described above are performed under high-pressure conditions, the temperature of the dispersion rises, and the photothermographic material produced using the organic silver salt dispersion obtained thereby has fog. There was a problem that it became expensive. Therefore, the dispersibility of the organic silver salt particles is good,
Further, there has been a demand for a method for producing an organic silver salt dispersion capable of producing a low-fogging photothermographic material.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to adjust the temperature of a raw material solution comprising at least an organic silver salt and a solvent before dispersion to -95 ° C. to 35 ° C., and then disperse the mixture under pressure. By improving the dispersibility of the organic silver salt, and by suppressing an undesired rise in temperature during dispersion,
An object of the present invention is to provide a photothermographic material having reduced fog.

[0008]

[Means for Solving the Problems] In a method for producing an organic silver salt dispersion in which a raw material liquid comprising at least an organic silver salt and a solvent is dispersed under a pressure of 580 kgf / cm ² or more, the temperature of the raw material liquid before dispersion is adjusted to −95 ° C. to 35 ° C. And a method wherein the pressure is Akgf / cm ² and the temperature before dispersing the raw material liquid is B ° C., wherein the following conditional expression is satisfied:

50> 2A / 100 + B 2. A photothermographic material comprising an organic silver salt dispersion produced by the production method as described in 1 above.

Hereinafter, the present invention will be described in more detail.

The method for dispersing the organic silver salt used in the present invention will be described.

In the present invention, when the organic silver salt is dispersed by applying a pressure of 580 kgf / cm ² or more to a raw material solution comprising at least an organic silver salt and a solvent, the temperature before the dispersion is -95 ° C. to 35 ° C. And the pressure is Akg
f / cm ² , and when the temperature before dispersion of the raw material liquid is B ° C., by satisfying the following conditional expression, even under high-pressure dispersion conditions, while maintaining good dispersibility of the organic silver salt, In addition, the present invention has reached a method of dispersing an organic silver salt which can suppress an increase in fog of organic silver salt particles caused by an undesired temperature rise during dispersion of the organic silver salt.

Conditional formula: 50> 2A / 100 + B In the present invention, a high-pressure homogenizer is used to disperse a raw material liquid comprising at least an organic silver salt and a solvent, and is used in combination with a ball mill, an attritor, a sand mill, a homomixer and the like. You may.

In the present invention, the temperature of the raw material liquid is adjusted to -95 ° C. to 35 ° C. before dispersing the raw material liquid. From the viewpoint of suppression, more preferably -95 ° C to 25 ° C
° C.

However, the lower limit of the temperature is higher than the freezing point of the solvent used for dispersion.

In the present invention, the pressure applied to the dispersion is preferably 58 to improve the dispersibility of the organic silver salt.
A pressure of 0 kgf / cm ² or more is applied.
00 kgf / cm ² , more preferably
0 kgf / cm ² , particularly preferably 1,000 kgf / cm ^2.
To 2,000 kgf / cm ² .

The raw material liquid used in the present invention contains at least an organic silver salt and a solvent.

As the above-mentioned solvent, water, alcohols, esters, aromatic hydrocarbons, ketones and the like are preferably used.

Examples of the alcohol include methanol, ethanol, propanol and the like.

Examples of the esters include ethyl acetate and butyl acetate.

The aromatic hydrocarbons include benzene, toluene, xylene and the like.

The above ketones include acetone, 2-butanone (MEK) and the like.

Among the above-mentioned solvents, acetone and 2-butanone (MEK) are preferably used from the viewpoint of the dispersibility of the organic silver salt and the like.
-Butanone (MEK).

The ratio of the organic silver salt to the solvent used in the present invention is such that the amount of the organic silver salt is 10 to the solvent.
50 wt% is preferable, and 20 to 40 wt% is more preferable.
%.

The organic silver salt used in the present invention is a reducible silver source and is an organic acid containing a reducible silver ion source. Examples of the organic acid used in the present invention include an aliphatic carboxylic acid, a carbocyclic carboxylic acid, a heterocyclic carboxylic acid, and a heterocyclic compound.
An aliphatic carboxylic acid having 0, preferably 15 to 25 carbon atoms) and a heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used. Moreover, when the ligand is 4.0-10.
Organic silver salt complexes having a total stability constant for silver ions of 0 are also useful.

Examples of the organic silver salt used in the present invention include Research Disclosure No. 170.
And silver salts of fatty acids (eg, silver salts of gallic acid, oxalic acid, behenic acid, arachidic acid, stearic acid, palmitic acid, lauric acid, etc.); Carboxyalkylthiourea salts (eg, 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea); polymerization reaction products of aldehydes and hydroxy-substituted aromatic carboxylic acids (E.g., aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.) and hydroxy-substituted aromatic carboxylic acids (e.g., salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc.) Silver complex or the like of a polymerization reaction product of), a silver salt or complex of a thione (for example, 3- (2-carbo) (Silethyl) -4-hydroxymethyl-4-thiazoline-2-thione and 3-carboxymethyl-4-thiazoline-2-thione), imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, -Amino-5-benzylthio-1,2,4-triazole and benzotriazole, and complexes and salts of silver with nitrogen acids; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides . Among the organic silver salts described above, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate and silver stearate are more preferably used.

The organic silver salt used in the present invention preferably has an average particle size of 1 μm or less and is monodispersed. The average particle size of the organic silver salt refers to the diameter of a sphere equivalent to the volume of the organic silver salt particles when the particles of the organic silver salt are, for example, spherical, rod-shaped, or tabular particles. The average particle size is preferably from 0.01 μm to 0.8 μm, particularly preferably from 0.05 μm to 0.5 μm. The monodispersion has the same meaning as that of silver halide, and the monodispersity is preferably 1% to 30%.

In the present invention, the organic silver salt has an average particle size of 1
It is more preferable that the particles are monodisperse particles having a particle size of not more than μm.

As the organic silver salt particles, it is preferable that tabular grains account for at least 60% of the total projected area of all organic silver grains. The tabular grains used in the present invention are grains having an aspect ratio (abbreviated as AR) of 3 or more, which is a ratio between the average particle diameter and the thickness, which is represented by the following formula.

AR = average particle size (μm) / thickness (μm) The organic silver salt particles are dispersed and pulverized together with a binder and a surfactant using, for example, a ball mill.
The shape described above is also possible.

In the present invention, in order to prevent devitrification of the photothermographic material, the total amount of silver halide and organic silver salt is 0.5 g or more and 2.2 g or less per m ² in terms of silver. Is preferred. With this range, a high-contrast image can be obtained. The amount of silver halide based on the total amount of silver is
The weight ratio is 50% or less, preferably 25% or less, more preferably between 0.1% and 15%. This silver halide may be added to the organic silver salt dispersion by any method,
At this time, the silver halide is preferably arranged so as to be close to the organic silver salt.

The silver halide grains used in the present invention function as an optical sensor. In the present invention, the average particle size is preferably 0.1 μm or less, more preferably 0.01 μm to 0.1 μm, particularly preferably 0.01 μm to 0.1 μm, in order to suppress white turbidity after image formation and obtain good image quality. It is 0.02 μm to 0.08 μm.

When the silver halide grains are cubic or octahedral, so-called normal crystals, the grain size refers to the length of the edge of the silver halide grains. In the case of non-normal crystals, for example, in the case of spherical, rod-shaped, or tabular grains, the diameter of a sphere equivalent to the volume of silver halide grains is indicated. Further, the silver halide is preferably monodispersed.

The term "monodispersion" as used herein means a case where the degree of monodispersion determined by the following equation is 40% or less. In the present invention, the monodispersity is more preferably 30% or less, particularly preferably 0.1% or more and 20% or less.

Monodispersity = (standard deviation of grain size) / (average grain size) × 100 In the present invention, the silver halide grains have an average grain size of 0.1.
μm or less and more preferably monodisperse particles,
By setting it in this range, the granularity of the image is also improved.

The shape of the silver halide grains is not particularly limited, but it is preferable that the ratio occupied by the Miller index [100] plane is high, and this ratio is 50% or more, and more preferably 7%.
It is preferably at least 0%, particularly preferably at least 80%. The ratio of the Miller index [100] plane is determined by the T.M. Tani, J .; Imaging Sci. , 29,
165 (1985).

Another preferred form of silver halide is tabular grains. The term "tabular grain" as used herein means that the thickness in the vertical direction is h.mu.
When m, the aspect ratio = r / h means 3 or more. Among them, the aspect ratio is more preferably 3 or more and 50 or less. The particle size is preferably 0.1 μm or less, more preferably 0.01 μm to 0.08 μm. These are described in U.S. Patent Nos. 5,264,337, 5,314,798, and 5,320,958, and the like. Can be.

When these tabular grains are used in the present invention, the sharpness of an image is further improved. The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. AgX particles used in the present invention are P.A. Glafk
Chimie et Physique P
photographique (Paul Montel)
G., 1967); F. Duffin's Pho
graphical Emulsion Chemis
try (published by The Focal Press, 1966)
Year), V. L. Mak by Zelikman et al
ing and Coating Photograph
hic Emulsion (The Focal Pr
ess, 1964) and the like, and can be prepared using an Ag emulsion prepared by a method described in US Pat.

The silver halide used in the present invention is preferably contained in an amount of 0.75 to 30% by weight based on the organic silver salt.

The silver halide used in the present invention preferably contains an ion or a complex ion of a metal belonging to Groups 6 to 11 of the periodic table. Examples of the above metals include W, Fe, Co, Ni, Cu, Ru, Rh, Pd,
Re, Os, Ir, Pt, and Au are preferred.

The ions of these metals can be introduced into silver halide in the form of complex ions. In the present invention, the transition metal complex ion is preferably a six-coordinate complex ion represented by the following general formula.

In the formula [ML ₆ ] ^m , M is a transition metal selected from the elements of Groups 6 to 11 of the periodic table, L is a bridging ligand, and m is 0,-, 2- or 3- . Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate,
Terrocyanate, each ligand of azide and aquo, nitrosyl, thionitrosyl and the like, preferably aquo,
And nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

Particularly preferred examples of M are rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) and osmium (Os).

Specific examples of transition metal complex ions are shown below, but the present invention is not limited to these.

[0045] 1: [RhCl _6] ^3- 2: [RuCl _6] ^3- 3: [ReCl _6] ^3- 4: [RuBr _6] ^3- 5: [OsCl _6] ^3- 6: [IrCl _6] ^{4 -} 7: [Ru (NO) Cl _5] ^2- 8: [RuBr ₄ (H ₂ O)] ^2- 9: _{[Ru (NO) (H 2 O} ) Cl 4 ] ^- 10: [RhCl ₅ (H ₂ O)] ^2- 11: [Re (NO) Cl _5] ^2- 12: [Re (NO) CN _5] ^2- 13: [Re (NO) ClCN _4] ^2- 14: [Rh (NO) ₂ Cl _4] ^- 15: _{[Rh (NO) (H 2 O} ) Cl 4 ] ^- 16: [Ru (NO) CN _5] ^2- 17: [Fe (CN) _6] ^3- 18: [Rh (NS) Cl _5] ^2- 19: [Os (NO) Cl _5] ^2- 20: [Cr (NO) Cl _5] ^2- 21: [Re (NO) Cl _5] ^- 22: [Os (NS) Cl ₄ (TeCN )] ^2-23 : [Ru (NS) Cl _5] ^2- 24: _{[Re (NS) Cl 4 (SeCN} ) ] ^2- 25: [Os (NS) Cl (SCN) 4 ] ^2- 26: [Ir (NO) Cl _5] ^2-27 : [Ir (NS) Cl ₅ ] ^2- The ion or complex ion of these metals may be of one type, or two or more of the same and different metals may be used in combination. The content of these metal ions or complex ions is generally 1 × 1 per mole of silver halide.
0 ^-9 to 1 × 10 ^-2 mol is suitable, preferably 1 × 1
It is 0 ^-8 to 1 × 10 ^-4 mol.

Compounds which provide these metal ions or complex ions are added during silver halide grain formation,
It is preferably incorporated into silver halide grains, and may be added at any stage before and after preparation of silver halide grains, that is, nucleation, growth, physical ripening, and chemical sensitization. It is preferably added at the stage of physical ripening, more preferably at the stage of nucleation and growth, and most preferably at the stage of nucleation.

In the addition, the compound may be added in several divided portions, may be added uniformly in the silver halide grains, or may be added uniformly to the silver halide grains.
-306236, 3-167545, 4-76
No. 534, No. 6-110146, No. 5-273683
As described in Japanese Patent Application Laid-Open No. H10-284, etc., the particles can be contained in the particles with a distribution. Preferably, a distribution can be provided inside the particles.

These metal compounds can be added by dissolving them in water or a suitable organic solvent (eg, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution of a powder or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during grain formation, or a silver salt solution and a halide solution are used. When they are mixed simultaneously, they are added as a third aqueous solution to prepare silver halide grains by a three-liquid simultaneous mixing method, a method in which a required amount of an aqueous solution of a metal compound is charged into a reaction vessel during grain formation, or There is a method in which another silver halide grain doped with metal ions or complex ions in advance during the preparation of silver halide is added and dissolved. In particular, a method of adding an aqueous solution of a powder of a metal compound or an aqueous solution in which a metal compound and NaCl and KCl are dissolved together is added to a water-soluble halide solution.

When adding to the surface of the particles, a required amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particles, during or at the end of physical ripening, or at the time of chemical ripening.

The silver halide grains used in the present invention may or may not be desalted after grain formation. When desalting is performed, methods known in the art such as a noodle method and a flocculation method are used. Can be desalted by washing with water.

The silver halide grains used in the present invention are preferably chemically sensitized. Preferred chemical sensitization methods are sulfur sensitization, as is well known in the art,
Selenium sensitization and tellurium sensitization can be used. Further, a noble metal sensitization method or a reduction sensitization method of a gold compound, platinum, palladium, an iridium compound or the like can be used. As the compound preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method, known compounds can be used, and the compounds described in JP-A-7-128768 can be used. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides,
Bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, compounds having a P = Te bond, tellurocarboxylates, Te-organyltellurocarboxylates, Use of (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, etc. Can be. Compounds preferably used for the noble metal sensitization method include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, US Pat. No. 2,448,060, British Patent No. 618,061 and the like. Can be preferably used.

As specific compounds for the reduction sensitization method, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like are used. be able to. Further, reduction sensitization can be achieved by ripening the emulsion while maintaining the pH of the emulsion at 7 or more or the pAg at 8.3 or less. Further, reduction sensitization can be achieved by introducing a single addition portion of silver ion during grain formation.

The organic silver salt used in the present invention is a reducible silver source, and is an organic acid containing a reducible silver ion source. Examples of the organic acid used in the present invention include an aliphatic carboxylic acid, a carbocyclic carboxylic acid, a heterocyclic carboxylic acid, and a heterocyclic compound.
An aliphatic carboxylic acid having 0, preferably 15 to 25 carbon atoms) and a heterocyclic carboxylic acid having a nitrogen-containing heterocyclic ring are preferably used. Moreover, when the ligand is 4.0-10.
Organic silver salt complexes having a total stability constant for silver ions of 0 are also useful.

Examples of the silver salt of an organic acid used in the present invention include Research Disclosure No. 170.
And silver salts of fatty acids (eg, silver salts of gallic acid, oxalic acid, behenic acid, arachidic acid, stearic acid, palmitic acid, lauric acid, etc.); Carboxyalkylthiourea salts (eg, 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea); polymerization reaction products of aldehydes and hydroxy-substituted aromatic carboxylic acids (E.g., aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.) and hydroxy-substituted aromatic carboxylic acids (e.g., salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc.) Silver complex or the like of a polymerization reaction product of), a silver salt or complex of a thione (for example, 3- (2-carbo) (Silethyl) -4-hydroxymethyl-4-thiazoline-2-thione and 3-carboxymethyl-4-thiazoline-2-thione), imidazole, pyrazole, urazole, 1,2,4-thiazole and 1H-tetrazole, -Amino-5-benzylthio-1,2,4-triazole and benzotriazole, and complexes and salts of silver with nitrogen acids; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptides . Among the organic silver salts described above, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate and silver stearate are more preferably used.

The dispersion of the aqueous organic silver salt used in the present invention can be obtained by mixing silver nitrate and an alkali metal salt of an organic acid. When the organic silver salt is formed, silver nitrate and silver halide are simultaneously added and mixed. Manufactured using a mixing method.

For example, after an alkali metal hydroxide (eg, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to prepare an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.) By using a control double jet method, silver nitrate and silver halide can be simultaneously added and mixed to prepare an aqueous organic silver salt dispersion used in the present invention.

Further, the aqueous organic silver salt dispersion used in the present invention can be prepared by a so-called control triple jet method in which an alkali metal salt of an organic acid, silver nitrate and silver halide are simultaneously added and mixed, respectively. .

In the present invention, from the viewpoint of simplicity in the production process, the method for producing an aqueous organic silver salt dispersion using the above-described controlled double jet method is preferably used. From the viewpoint of producing a high-sensitivity photothermographic material, the method for producing an aqueous organic silver salt dispersion using the above-described control triple jet method is preferably used.

The photothermographic material of the present invention preferably contains a reducing agent. Examples of suitable reducing agents are described in U.S. Patent Nos. 3,770,448, 3,773,512, 3,593,863, and Research Dis.
Closure Nos. 17029 and 29996, and include: Aminohydroxycycloalkenones (for example, 2-hydroxypiperidino-2)
-Cyclohexenone); aminoreductone esters (e.g., piperidinohexose reductone monoacetate) as precursors of reducing agents; N-hydroxyurea derivatives (e.g., N-p-methylphenyl-N-hydroxy) Urea); hydrazones of aldehydes or ketones (eg, anthracene aldehyde phenylhydrazone); phosphoramidophenols; phosphoramidoanilines; polyhydroxybenzenes (eg, hydroquinone, t-butyl-hydroquinone, isopropylhydroquinone, and (2) , 5-dihydroxy-phenyl) methylsulfone); sulfhydroxamic acids (eg, benzenesulfhydroxamic acid); sulfonamidoanilines (eg, 4- (N-
Methanesulfonamido) aniline); 2-tetrazolylthiohydroquinones (for example, 2-methyl-5- (1-
Phenyl-5-tetrazolylthio) hydroquinone); tetrahydroquinoxalines (e.g., 1,2,3,4-
Amidooxins; Azines (for example, a combination of an aliphatic carboxylic acid arylhydrazide and ascorbic acid); a combination of polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine; Hydroxamic acids; Azines and sulfone Combinations of amidophenols; α-cyanophenylacetic acid derivatives; bis-β-naphthol and 1,3
5-pyrazolones; sulfonamidophenol reducing agents; 2-phenylindane-1,3-dione and the like; chromans;
Dihydropyridines (for example, 2,6-dimethoxy-
3,5-dicarbethoxy-1,4-dihydropyridine); bisphenols (for example, bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, bis (6-hydroxy-m-tri) mesitol (Mesi
tol), 2,2-bis (4-hydroxy-3-methylphenyl) propane, 4,5-ethylidene-bis (2-
t-butyl-6-methyl) phenol), ultraviolet-sensitive ascorbic acid derivatives and 3-pyrazolidones. Among them, particularly preferred reducing agents are hindered phenols.
Examples of the hindered phenols include compounds represented by the following general formula (A).

[0060]

Embedded image

In the formula, R is a hydrogen atom or a group having 1 carbon atom.
To 10 alkyl groups (for example, butyl group, 2,4,4-
R ′ and R ″ represent an alkyl group having 1 to 5 carbon atoms (eg, a methyl group, an ethyl group, a t-butyl group, etc.).

Specific examples of the compound represented by formula (A) are shown below. However, the present invention is not limited to these.

[0063]

Embedded image

[0064]

Embedded image

The amount of the reducing agent including the compound represented by formula (A) is preferably 1 × 1 per mol of silver.
It is from 0 ^-2 to 10 mol, especially from 1 x 10 ^{-2 to} 1.5 mol.

The photothermographic material of the present invention may contain an antifoggant. What is known as the most effective antifoggant is mercury ion. The use of a mercury compound as an antifoggant in a light-sensitive material is disclosed in, for example, US Pat. No. 3,589,903. However, mercury compounds are environmentally unfriendly. Non-mercury antifoggants include, for example, US Pat.
Nos. 075 and 4,452,885 and JP-A-59-5959.
Antifoggants such as those disclosed in US Pat.

Particularly preferred non-mercury antifoggants are US Pat. Nos. 3,874,946 and 4,756,999.
-C (X ₁ ) (X ₂ ) as disclosed in US Pat.
(X ₃ ) (where X ₁ and X ₂ represent a halogen atom, X ₃
Is a heterocyclic compound having at least one substituent represented by the following formula: As examples of suitable antifoggants, compounds described in paragraphs [0030] to [0036] of JP-A-9-288328 are preferably used.

As another example of a preferred antifoggant, JP-A-9-90550, paragraph [006]
2] to [0063]. Still other suitable antifoggants are described in U.S. Pat.
8,523 and British Patent Application No. 9300147.7.
No. 9311790.1.

It is preferable to add a toning agent to the photothermographic material of the present invention for the purpose of improving the silver tone after development. Examples of suitable toning agents are Research Discl
No. 17029, which includes the following:

Imides (for example, phthalimide); cyclic imides, pyrazolin-5-ones and quinazolinones (for example, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2 , 4-thiazolidinedione); naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, hexamine trifluoroacetate of cobalt), mercaptans (eg, 3
-Mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (for example,
N- (dimethylaminomethyl) phthalimide); blocked pyrazoles, isothiuronium (isoth
uronium) derivatives and certain photobleaching combinations (eg, N, N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8-
A combination of (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole; a merocyanine dye (e.g., 3-ethyl-5-((3-ethyl -2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene) -2-thio-2,4
Oxazolidinedione); phthalazinone, a phthalazinone derivative or a metal salt of these derivatives (for example, 4-
(1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3
-Dihydro-1,4-phthalazinedione); a combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); phthalazine + phthalate Combinations of acids; phthalazine (including adducts of phthalazine) and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and anhydrides thereof (for example,
Combination with at least one compound selected from phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride; quinazolinediones, benzoxazine, naloxazine derivatives; benzoxazine-2,4-dione (Eg, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetric-triazines (eg, 2,4-dihydroxypyrimidine), and tetraazapentalene derivatives (eg,
3,6-dimercapto-1,4-diphenyl-1H, 4
H-2,3a, 5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

The photothermographic materials of the present invention include, for example, JP-A-63-159814, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, and JP-A-6-259561.
3-304242, 63-15245, U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, and 4,835. No. 096 can be used.

Useful sensitizing dyes for use in the present invention include, for example, Research Disclosure Item
Section 17643 IV-A (p. 23, December 1978),
Item 1831X (August 1978, p. 437)
Or cited in the literature cited. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, JP-A-9-34078, JP-A-9-54409, and JP-A-9-80
No. 679 is preferably used.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained in order to control development by suppressing or accelerating development, to improve spectral sensitization efficiency, and to improve storage stability before and after development. be able to.

When a mercapto compound is used in the present invention, it may be of any structure,
Those represented by -SS-Ar are preferred. In the formula, M is a hydrogen atom or an alkali metal atom, and Ar represents an aromatic ring or a condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. As the aromatic ring, an aromatic carbon ring and a heteroaromatic ring are used, and in the present invention, a heteroaromatic ring is preferably used. As the heteroaromatic ring, for example, benzimidazole, naphthymidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole,
Benzoselenazole, benzotellazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazolinone. This heteroaromatic ring is, for example,
A halogen atom (eg, Br and Cl, etc.), a hydroxy group, an amino group, a carboxy group, an alkyl group (eg,
A substituent consisting of one or more carbon atoms, preferably having 1 to 4 carbon atoms, and an alkoxy group (for example, having one or more carbon atoms, preferably having 1 to 4 carbon atoms) It may have one selected from a group. Examples of the mercapto-substituted heteroaromatic compound include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzothiazole, 3-mercapto-1,2,4-triazole, 2 -Mercaptoquinoline, 8-mercaptopurine, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-hydroxy-2-mercaptopyrimidine, 2-mercapto-4-phenyloxazole, etc., and the present invention. Is not limited to these.

In the present invention, it is preferable to include a matting agent on the photosensitive layer side, and it is preferable to dispose a matting agent on the surface of the photosensitive material in order to prevent damage to the image after thermal development. It is preferable that the content of the agent is 0.5 to 30% by weight based on all binders on the emulsion layer side.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as the inorganic substance, silica described in Swiss Patent No. 330,158 or the like,
Glass powder described in French Patent No. 1,296,995,
Alkaline earth metals or carbonates such as cadmium and zinc described in British Patent No. 1,173,181 can be used as a matting agent. Examples of organic substances include starch described in U.S. Pat. No. 2,322,037, starch derivatives described in Belgian Patent No. 625,451 and British Patent No. 981,198, and Japanese Patent Publication No. 44-3643. Polyvinyl alcohol, Swiss Patent 330,15
An organic matting agent such as polystyrene or polymethacrylate described in No. 8, etc., polyacrylonitrile described in U.S. Pat. No. 3,079,257, etc., and polycarbonate described in U.S. Pat. No. 3,022,169 is used. be able to.

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.

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

Here, the variation coefficient of the particle size distribution is a value represented by the following equation.

(Standard deviation of particle size) / (average value of particle size) × 100 The matting agent used in the present invention can be contained in any constituent layer, but in order to achieve the object of the present invention, It is preferably a constituent layer other than the photosensitive layer, and more preferably the outermost layer as viewed from the support.

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

In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layer in order to improve the chargeability. These may be contained in any layer, but are preferably contained in an undercoat layer, a backing layer, a layer between the photosensitive layer and the undercoat, and the like.

In the present invention, US Pat.
The conductive compounds described in No. 773 columns 14 to 20 are preferably used.

Various additives may be added to any of the photosensitive layer, the non-photosensitive layer, and other constituent layers. In the photothermographic 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 in addition to the above. These additives and the other additives mentioned above are used in Research Disclosure.
re Item 17029 (June 1978, p. 9-
The compound described in 15) can be preferably used.

Binders suitable for the photothermographic material of the present invention are transparent or translucent, generally colorless, and include natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic,
Poly (vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid) ), Copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (ester) ), Poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide),
Poly (carbonate) s, poly (vinyl acetate),
There are cellulose esters and poly (amides). It may be hydrophilic or non-hydrophilic. In order to protect the surface of the light-sensitive material and prevent abrasion, a non-light-sensitive layer may be provided outside the light-sensitive layer. The binder used for these non-photosensitive layers may be the same as or different from the binder used for the photosensitive layers.

In the present invention, in order to increase the speed of thermal development, the amount of the binder in the photosensitive layer is 1.5 to 10 g / m ^2.
It is preferred that More preferably, 1.7 to 8 g
/ M ² .

The support used in the present invention may be a plastic film (for example, polyethylene terephthalate, polycarbonate, or the like) in order to prevent deformation of an image after development processing.
Polyimide, nylon, cellulose triacetate, polyethylene naphthalate) are preferred.

Among them, a preferred support is a support made of polyethylene terephthalate (hereinafter abbreviated as PET) and a plastic (hereinafter abbreviated as SPS) containing a styrene-based polymer having a syndiotactic structure. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

Further, a heat-treated plastic support may be used. The plastics to be employed include the above-mentioned plastics. The heat treatment of the support means that after forming these supports and before the photosensitive layer is applied, at a temperature higher than the glass transition point of the support by 30 ° C. or more,
Preferably at a temperature higher than 35 ° C., more preferably 40 ° C.
It is preferable to heat at a temperature higher than ℃. However, the effect of the present invention cannot be obtained by heating at a temperature exceeding the melting point of the support.

Next, the plastic used will be described.

PET is composed of polyethylene terephthalate in all of the polyester components. In addition to polyethylene terephthalate, terephthalic acid, naphthalene-2,6-dicarboxylic acid, isophthalic acid, butylene dicarboxylic acid, and 5-sodium sulfo acid are used as acid components. A polyester containing a modified polyester component of isophthalic acid, adipic acid or the like and a glycol component such as ethylene glycol, propylene glycol, butanediol, cyclohexanedimethanol or the like in an amount of 10 mol% or less of the entire polyester may be used.

SPS is a polystyrene having steric regularity unlike ordinary polystyrene (atactic polystyrene). The regular stereoregular structure part of SPS is called a racemo chain, and it is preferable that there are more regular parts such as two, three, five or more. In the present invention, the racemo chain is 2 It is preferably 85% or more in the chain, 75% or more in the three chains, 50% or more in the five chains, and 30% or more in the further chains. The polymerization of SPS can be carried out according to the method described in JP-A-3-131843.

As the method of forming a film of a support and the method of producing an undercoat used in the present invention, known methods can be used, and preferably, paragraph [0030] of JP-A-9-50094 is used.
To [0070].

The photothermographic material of the present invention is for forming a photographic image by a heat development process, and comprises a reducible silver source (organic silver salt), a photosensitive silver halide, a reducing agent and, if necessary, silver. It is preferable that the photothermographic material contains a color toning agent which suppresses the color tone of the present invention in a state of being usually dispersed in an (organic) binder matrix. The photothermographic material of the present invention is stable at room temperature, but is exposed to a high temperature (for example, 80 ° C. to 14 ° C.).
(0 ° C.). Heating generates silver through an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This oxidation-reduction reaction is accelerated by the catalytic action of the latent image generated on the silver halide upon exposure. The silver formed by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image. This reaction process proceeds without supplying a processing liquid such as water from the outside.

The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. To control the amount or wavelength distribution of light passing through the photosensitive layer, a filter dye layer on the same side as the photosensitive layer and / or an antihalation dye layer, a so-called backing layer, may be formed on the opposite side. A dye or pigment may be included in the active layer. As the dye to be used, any compound may be used as long as it has a desired absorption in a desired wavelength range, and examples thereof include JP-A-59-6481 and JP-A-59-1.
No. 82436, U.S. Pat. No. 4,271,263, U.S. Pat. No. 4,594,312, EP 533,008
No. 652,473, JP-A-2-216
No. 140, JP-A-4-348339, JP-A-7-19
Compounds described in JP-A-1432 and JP-A-7-301890 are preferably used.

These non-photosensitive layers preferably contain the above-mentioned binder and matting agent, and may further contain a sliding agent such as a polysiloxane compound, wax and liquid paraffin.

The photosensitive layer may be composed of a plurality of layers, and the sensitivity may be changed to a high-sensitivity layer / low-sensitivity layer or a low-sensitivity layer / high-sensitivity layer in order to adjust the gradation.

The details of the photothermographic material are described in, for example, US Pat. Nos. 3,152,904 and 3,457,0
No. 75; Morgan (Dry Silver Pho)
Graphic Material) "and D.C. Morgan and B.A. "The Silver System Treated by Heat (Therma)" by Shelly
llly Processed SilverSystem
ms) "(Imaging Processes and Materials
nd Materials) Neblette No. 8
Plate, Sturge, V.S. Walworth, A .; Shepp, 2nd page, 1969) and the like. Among them, the present invention is characterized in that an image is formed by thermally developing a photosensitive material at 80 to 140 ° C., and no fixing is performed. Therefore, the silver halide and the organic silver salt remaining in the unexposed area remain in the photosensitive material without being removed.

In the present invention, after the heat development processing,
The optical transmission density of the light-sensitive material containing the support at 400 nm is preferably 0.2 or less. A more preferable value of the optical transmission density is 0.02 or more and 0.2 or less.

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

[0101]

EXAMPLES Example 1 << Preparation of PET-undercoated photographic support >> A corona discharge treatment of 8 w / m ² · min was applied to both surfaces of a commercially available biaxially stretched and heat-fixed 100 μm thick PET film. On one surface, the following undercoating coating solution a-1 is applied so as to have a dry film thickness of 0.8 μm and dried to form an undercoating layer A-1. Liquid b-1 was dried to a thickness of 0.8 μm.
m and dried to form an antistatic subbing layer B
It was set to -1.

<< Undercoat Coating Solution a-1 >> Butyl acrylate (30% by weight) t-butyl acrylate (20% by weight) Styrene (25% by weight) 2-hydroxyethyl acrylate (25% by weight) copolymer latex liquid (Solid content 30%) 270 g (C-1) 0.6 g hexamethylene-1,6-bis (ethylene urea) 0.8 g Finish to 1 liter with water << Subtraction coating solution b-1 >> Butyl acrylate (40 weight %) Styrene (20% by weight) Glycidyl acrylate (40% by weight) copolymer latex liquid (solid content: 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 8g Finished to 1 liter with water Then, on the upper surface of the undercoat layer A-1 and the undercoat layer B-1,
A corona discharge of 8 w / m ² · min. Was performed, and the following lower coating liquid a-2 was coated on the lower coating layer A-1 with a dry film thickness of 0.1 μm.
As the undercoat layer A-2, the undercoat layer B-1 is coated on the undercoat layer B-1 with the following undercoat layer coating solution b-2 so as to have a dry film thickness of 0.8 μm. Coated as B-2.

<< Coating Solution a-2 for Lower Substrate >> Gelatin 0.4 g / m ² Weight (C-1) 0.2 g (C-2) 0.2 g (C-3) 0.1 g Silica particles ( (Average particle size: 3 μm) 0.1 g Finished to 1 liter with water << Lower coating solution for upper layer b-2 >> (C-4) 60 g Latex liquid containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 0 0.5 g (C-6) 12 g Polyethylene glycol (weight average molecular weight 600) 6 g Finish to 1 liter with water

[0104]

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[0105]

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<< Heat Treatment of Support >> In the above-mentioned undercoat drying step of the undercoated support, the support was heated at 140 ° C.
Thereafter, it was gradually cooled.

Back side coating: A solution having the following composition was applied.

Cellulose acetate (10% 2-butanone (MEK) solution) 15 ml / m ² dye-B 7 mg / m ² dye-C 7 mg / m ² Matting agent: monodispersity 15%, average particle size 10 μm Monodispersed silica 30 mg / m ² C ₉ H ₁₉ —C ₆ H ₄ —SO ₃ Na 10 mg / m ²

[0109]

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<< Preparation of Silver Halide Emulsion A >> 900 m of water
7.5 g of inert gelatin and 10 ml of potassium bromide
mg, and adjusted to a temperature of 35 ° C. and a pH of 3.0.
370 ml of an aqueous solution containing potassium bromide and potassium iodide (equimolar amounts to the above silver nitrate) in a molar ratio of 2) and K ₂ [Ir
(NO) to 1 × 10 ^-6 mol, and rhodium chloride salt per mole of silver of 1 × 10 ^-4 mol per mol of silver a Cl _5], p
While maintaining Ag 7.7, it was added by a controlled double jet method. Then 4-hydroxy-6-methyl-
Add 1,3,3a, 7-tetrazaindene and add NaOH
The pH was adjusted to 5 by adjusting the average particle size to 0.06 μm, the monodispersity to 10%, and the variation coefficient of the projected diameter area to 8%, [10
0] Cubic silver iodobromide grains having an area ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, followed by addition of 0.1 g of phenoxyethanol, pH 5.9, pA
g was adjusted to 7.5 to obtain a silver halide emulsion. Further, chemical sensitization was performed with chloroauric acid and inorganic sulfur.

<< Preparation of Sodium Salt Solution of Fatty Acid >>
8. 32.4 g of behenic acid and arachidic acid in 5 ml of pure water.
9 g and stearic acid 5.6 g were dissolved at 90 ° C. Next, 98 ml of a 1.5 M aqueous sodium hydroxide solution was added while stirring at a high speed. Next, after adding 0.93 ml of concentrated nitric acid, the mixture was cooled to 55 ° C. and stirred for 30 minutes to obtain a sodium salt solution of a fatty acid.

<< Preparation of Preform Emulsion of Fatty Acid Silver Salt and Silver Halide Emulsion A >> 15.1 g of the silver halide emulsion A was added to the above fatty acid sodium salt solution, and the pH was adjusted to 8.1 with a sodium hydroxide solution. Thereafter, 147 ml of a 1M silver nitrate solution was added over 7 minutes, the mixture was further stirred for 20 minutes, and ultrafiltration was performed to remove water-soluble salts. The resulting silver behenate was grains having an average grain size of 0.8 μm and a monodispersity of 8%. After the floc of the dispersion was formed, water was removed, washed with water six times, and dried to obtain a preform emulsion.

<< Preparation of Photosensitive Emulsion >> A solution prepared by dissolving 120 g of polyvinyl butyral (average molecular weight: 3000) in 700 g of methyl ethyl ketone and 80 g of toluene was added with 100 g of a preform emulsion, and a liquid stirred with a disper was prepared. Then, under the conditions shown in Table 1, the dispersion was carried out using a high-pressure homogenizer (Nanomizer LA53: manufactured by Nanomizer Co., Ltd.) to prepare each photosensitive emulsion.

[0114]

[Table 1]

The following layers were sequentially formed on the support,
A photothermographic material was prepared. The drying was performed at 60 ° C for 1 hour.
Performed in 5 minutes.

Photosensitive layer surface side coating Photosensitive layer 1: A solution having the following composition was coated and the silver amount was 2.1 g / m ^2.
It was applied so that it became.

Photosensitive emulsions shown in Table 1 240 g Sensitizing dye-1 (0.1% methanol solution) 1.7 ml Pyridinium bromide perbromide (6% methanol solution) 3 ml Calcium bromide (0.1% methanol solution) 1 0.7 ml Antifoggant-2 (10% methanol solution) 1.2 ml 2- (4-chlorobenzoylbenzoic acid (12% methanol solution) 9.2 ml 2-mercaptobenzimidazole (1% methanol solution) 11 ml tribromomethylsulfo Quinoline (5% methanol solution) 17 ml Reducing agent A-4 (20% methanol solution) 29.5 ml Hardening agent H (1% methanol solution) 3 ml

[0118]

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[0119]

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Surface protective layer: A solution having the following composition was applied on the photosensitive layer.

Acetone 35 ml / m ² Methyl ethyl ketone 17 ml / m ² Cellulose acetate 2.3 g / m ² Methanol 7 ml / m ² Phthalazine 250 mg / m ² 4-Methylphthalic acid 180 mg / m ² Tetrachlorophthalic acid 150 mg / m ² Tetrachlorophthale Acid anhydride 170 mg / m ² Matting agent: Monodispersity 10% Monodispersed silica with an average particle size of 4 μm 70 mg / m ² C ₉ H ₁₉ -C ₆ H ₄ —SO ₃ Na 10 mg / m ² << Evaluation of fog >> 820 nm After exposing the photosensitive material with a laser sensitometer equipped with a diode, the photographic material is heated to 120 ° C.
For 15 seconds, and the obtained image was evaluated by a densitometer. Dmin was measured using an optical densitometer. Table 2 shows the results.

<< Evaluation of Dispersibility >> The photosensitive emulsion was applied to a slide glass, and the size and number of the aggregates were relatively compared in four stages at a magnification of 100 times with an optical microscope. The best one having small and small aggregates was designated as 1, and the one having the largest aggregate with the largest number and poor dispersibility was designated as 4.

<< Comprehensive Judgment >> A sample having a relatively low fogging property and a good dispersibility was evaluated as ○, and the others were evaluated as ×.

[0124]

[Table 2]

From Table 2, it can be seen that the photothermographic material sample of the present invention yielded an organic silver salt dispersion having better dispersibility of the organic silver salt as compared with the comparative example. It is clear that the sample after exposure and processing has low fog.

[0126]

According to the present invention, a photothermographic material having improved dispersibility of an organic silver salt, produced by the production method thereof, and having reduced fog can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H123 AB00 AB03 AB23 BC00 BC11 BC12 CA00 CA22 CB00 CB03 4G065 AA01 AA07 AA10 AB01Y AB02Y AB03Y AB11X AB12X AB19X AB40X BA07 BB06 CA11 CA30 DA09 EA05 EA10 FA01 4H048 ABB BB11 BC51 BC52 VA20 VA57 VB30

Claims (2)

[Claims] 1. A method for producing an organic silver salt dispersion in which a raw material liquid containing at least an organic silver salt and a solvent is dispersed under a pressure of 580 kgf / cm ² or more, wherein the temperature of the raw material liquid before dispersion is −95 ° C. An organic silver salt dispersion characterized by satisfying the following conditional expression when the temperature is adjusted to 35 ° C., and the pressure is Akgf / cm ² , and the temperature before the dispersion of the raw material liquid is B ° C. Manufacturing method. 50> 2A / 100 + B 2. A photothermographic material comprising an organic silver salt dispersion produced by the production method according to claim 1.