JP2000098529A - Manufacture of heat-developable photosensitive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-developable photosensitive material low in fog and to provide a method for manufacturing the heat-developable photosensitive material small in a process equipment load. SOLUTION: In a method for manufacturing this heat-developable photosensitive material in which a coating liquid containing at least photosensitive silver halide grains and at least an organic silver salt are used, the photosensitive silver halide grains and the organic silver salt are separately prepared, the photosensitive silver halide grains are added and mixed to the organic silver salt dispersion dispersed into a binder and then, after wet dispersion, the application is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a photothermographic material.

[0002]

2. Description of the Related Art A method of forming an image by thermal development is described in, for example, U.S. Pat. Nos. 3,152,904 and 3,45,904.
7,075, and D.C. Morgan and B.A. "Thermally Processed Silver System" by Shelly
ed Silver Systems) "(Imaging Processes and Materials (Imag)
ing Process Materials
Neblette Eighth Edition, Sturge
e), V.I. Walworth, A .;
Shepp, page 2, 1969).

Such a light-sensitive material is prepared by adding a reducible non-photosensitive silver source (for example, an organic silver salt), a catalytically active amount of a photocatalyst (for example, a light-sensitive silver halide), and a silver reducing agent to a normal (organic) material. It is contained in a dispersed state in the binder matrix. The photosensitive material is stable at normal temperature, but when heated to a high temperature (for example, 80 ° C. or higher) after exposure, silver is reduced through a redox reaction between a reducible silver source (which functions as an oxidizing agent) and a reducing agent. Generate This oxidation-reduction reaction is promoted by the catalytic action of the latent image generated by the exposure. The silver formed by the reaction of the reducible silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas, resulting in the formation of an image.

[0004] Methods of forming photosensitive silver halide are well known in the art and include, for example, those described in Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,458. Although it can be used, conventionally, for example, US Pat.
No. 43 or JP-A-10-62899, a photosensitive silver halide emulsion prepared separately when forming an organic acid soap (organic silver soap was changed to organic acid soap) or when forming an organic silver salt Was added, followed by drying or extraction to remove the solid phase of the organic silver salt and photosensitive silver halide grains, and dispersing the solid phase in a solvent and a binder to obtain an emulsion for the photosensitive layer.

However, in such a method, light is required to be shielded in the step of forming an organic acid soap or an organic silver salt, and the load on the process equipment is significantly increased. In addition, since the photosensitive silver halide must be mixed and dispersed with the organic silver salt generated during the reaction, the time required for coating is long, and the photosensitive silver halide is required during the production process. There were problems such as particle damage and fogging that could not be ignored.

JP-A-8-297345 discloses that a separately prepared silver halide crystal is mixed with a long-chain fatty acid silver salt to obtain a photothermographic material. An organic acid soap is formed in the presence of a photosensitive silver halide and then an organic silver salt is formed by adding silver nitrate, or a halogen compound is added in the presence of the organic silver salt after the formation of the organic silver salt. , Forming silver halide, no separately prepared embodiments are shown.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a photothermographic material which can produce a photothermographic material having less fog and which has a small load on process equipment.

[0008]

[Means for Solving the Problems] In a method for producing a photothermographic material using a coating solution containing at least photosensitive silver halide particles and an organic silver salt, the photosensitive silver halide particles and the organic silver salt are separately prepared; A method for producing a photothermographic material, wherein silver halide particles are added to and mixed with an organic silver salt dispersion dispersed in a binder, and then wet-dispersed, followed by coating.

[0009] 2. In a method for producing a photothermographic material using a coating solution containing at least photosensitive silver halide particles and an organic silver salt, the photosensitive silver halide particles and the organic silver salt are each contained in the same solvent and the same binder. A method for producing a photothermographic material, wherein the photothermographic material is separately dispersed, mixed, and coated.

Hereinafter, the present invention will be described in detail.

In the method for producing a photothermographic material of the present invention, a coating solution prepared by the method shown in the following item (1) or (2) is used.

(1) The photosensitive silver halide grains and the organic silver salt are separately prepared, and the photosensitive silver halide grains are added to an organic silver salt dispersion dispersed in a solvent and a binder, mixed, and then mixed. Then, wet dispersion is performed to prepare a coating solution.

(2) The photosensitive silver halide grains and the organic silver salt are each prepared separately by using the same solvent and the same binder, and then the respective dispersions are mixed. A coating solution is prepared.

As described in the above item (2), a coating solution can be obtained by mixing a separately dispersed photosensitive silver halide particle dispersion and an organic silver salt dispersion. It is preferable that the mixture of the salt dispersion and the photosensitive silver halide particle dispersion is further subjected to wet dispersion.

The method of forming the photosensitive silver halide used in the present invention is a method well known in the art, for example, Research Disclosure No. 17029, June 1978, and US Pat. No. 3,700,
No. 458 can be used.
Usually, after the formation of the photosensitive silver halide, it is preferable to wash with demineralized water. At this time, it is preferable to remove as much gelatin as possible during the grain formation. After the desalted water washing, it is preferable to dehydrate in order to disperse in an organic solvent in the subsequent process.

The solid phase of the photosensitive silver halide grains can be removed by dehydration to remove the solid phase by a usual drying method, ie, a method using vacuum drying or freeze-drying, or a method of adding once to an organic solvent and adding it to a salt containing an aqueous phase. After extracting and obtaining the oil phase,
A method of removing by removing the solvent can be selected.

In the preparation of the photosensitive silver halide grains used in the present invention, the addition of photosensitive silver halide in an organic solvent and a binder alone results in poor dispersibility of the grains, resulting in poor performance due to aggregation and the like. I can't get it. For this reason, it is necessary to perform a dispersion operation after mixing with an organic silver salt or using a photosensitive silver halide emulsion alone.

The dispersion operation of the organic silver salt is also performed in advance.

As a method for dispersing the organic silver salt or photosensitive silver halide particles, a wet dispersion method generally known in the art can be used. The wet dispersion method used in the present invention refers to a dispersion method using a solvent or a binder at the time of dispersing an organic silver salt or photosensitive silver halide particles.

In the wet dispersion used in the present invention, a dispersion using a medium, a high-pressure dispersion method, a high-speed stirring dispersion, an ultrasonic dispersion, or the like can be used.

For example, as the high-speed stirring type dispersing machine used in the present invention, as shown in FIG. 1, an emulsifying and dispersing tank 1, a dissolver blade 2, and a vertical shaft 3 are used. FIG. 2 shows the dissolver blade 2. The rotation speed of the disperser is preferably 5,000 rpm or more,
10,000 rotation or more is more preferable. The dispersion time can be arbitrarily determined according to the desired particle size, but it is usually preferable to perform the dispersion for 10 minutes or more.

In the dispersion method using a high-pressure homogenizer, a method in which a plurality of high-speed flows of raw material liquids are generated and collided with each other to disperse, as disclosed in JP-A-8-137044, may be used. good.

The pressure applied to the raw material liquid is preferably 100 kgf / cm ² or more, and more preferably 500 kgf / cm ^2.
f / cm ² or more, most preferably 1,000 k
gf / cm ² . Further, the high-speed flow collision described above may be performed a plurality of times.

The temperature at the time of dispersion is not particularly limited, but is preferably a temperature at which the dispersion does not decompose due to a rise in temperature at the time of dispersion.

Before performing the wet dispersion, a pretreatment may be performed. As the pretreatment method, it is preferable to perform cyclic pulverization. Since the pretreatment results in an aggregate of fine particles, dispersion can be performed with less power in the subsequent dispersion step. As the pretreatment method described above, for example, a hammer mill, a high-speed rotary impact shear crusher such as an axial mill, a rolling ball mill,
Ball mills typified by vibrating ball mills, planetary crushers, etc. and jet crushers typified by air flow suction type, collision type, compound type, etc., tower mills, stirred bed type mills, flow tube type mills, annular type mills A known pulverizer such as a medium stirring type pulverizer represented by a mill may be used.

The solvent used for wet-dispersing the above organic silver salt or photosensitive silver halide grains includes:
Water, alcohols, esters, aromatic hydrocarbons, ketones and the like are used as preferred solvents.

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

Examples of the esters include ethyl acetate and butyl acetate.

Examples of the aromatic hydrocarbons include benzene, toluene, xylene and the like.

Examples of the ketones include acetone, methyl ethyl ketone (MEK) and the like.

Among the above-mentioned solvents, acetone and methyl ethyl ketone (MEK) are preferably used from the viewpoint of dispersibility of the photosensitive silver halide grains or the organic silver salt, and particularly preferred is methyl ethyl ketone (MEK). It is.

Further, in the present invention, it is preferable that the solvent used for dispersion of the organic silver salt and the solvent used for wet dispersion of the photosensitive silver halide grains be the same solvent.

The ratio of the photosensitive silver halide particles or the organic silver salt to the solvent used in the present invention is such that the amount of the photosensitive silver halide particles or the organic silver salt is 10 to 50% by weight based on the solvent. Preferably, more preferably, 20 to 4
0 wt%.

The binder used for the wet dispersion of the photosensitive silver halide grains and the organic silver salt includes natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as gelatin, gum arabic and poly (vinyl alcohol). ), Hydroxyethyl cellulose,
Cellulose acetate, cellulose acetate butyrate, poly (vinylpyrrolidone), 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) (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (ester), poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate) ), Poly (vinyl acetate), cellulose esters, and poly (amide). It may be hydrophilic or non-hydrophilic.

The photosensitive 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. (Enter the preferred ratio of photosensitive silver halide to organic silver salt and binder in the wet dispersion used in the present invention.) Further, in the present invention, in order to increase the speed of heat development, the photosensitive material is used. It is preferable that the binder amount of the functional layer is 1.5 to 10 g / m ² . More preferably, it is 1.7 to 8 g / m ² .

The photosensitive 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 photosensitive silver halide grains are cubic or octahedral so-called normal crystals, the grain size refers to the length of the edge of the photosensitive silver halide grains. In the case of non-normal crystals, for example, in the case of spherical, rod-shaped, or tabular grains, the diameter when considering a sphere equivalent to the volume of the photosensitive 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 particle size) / (average value of particle size) × 100 In the present invention, the photosensitive silver halide particles have an average particle size of 0.1 μm or less and are monodisperse particles. It is more preferable that the particle size be within this range, thereby improving the graininess of the image.

The shape of the photosensitive silver halide grains is not particularly limited, but the proportion occupied by the Miller index [100] plane is preferably high, and this proportion is preferably 50% or more.
Further, it is preferably at least 70%, 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 photosensitive silver halide is tabular grains. The term “tabular grains” as used herein means those having an aspect ratio = r / h of 3 or more when the thickness in the vertical direction is h μm, where the square root of the projected area is r μm. 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.
μm is preferred. These are disclosed in US Pat. No. 5,264,33.
No. 7, No. 5,314,798, No. 5,320,958
The target tabular grains can be obtained by referring to the above patents.

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 photosensitive 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. The above metals include W, Fe, Co, Ni, Cu, Ru, Rh, P
d, Re, Os, Ir, Pt, and Au are preferred.

These metal ions can be introduced into the photosensitive 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 general formula [ML ₆ ] ^m , M is a transition metal selected from 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.

[0048] 1: [RhCl _6] ^3- 2: [RuCl _6] ^3- 3: [ReCl _6] ^3- 4: [RuBr _6] ^3- 5: [OsCl _6] ^3- 6: [IrCl _6] ^{2 -} 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- also may with ions or complex ions one kind of these metals, the metal of the same kind of metal or different may be used alone or in combination. The content of these metal ions or complex ions is generally from 1 × 10 ^-9 to 1 × 10 ^-2 mol, preferably from 1 × 10 ^-8 mol, per mol of photosensitive silver halide. １1 × 10 ^-4 mol.

Compounds which provide these metal ions or complex ions are preferably added during the formation of the photosensitive silver halide grains and incorporated into the photosensitive silver halide grains. That is, it may be added at any stage before and after nucleation, growth, physical ripening, and chemical sensitization, but it is particularly preferable to add at the stage of nucleation, growth, and physical ripening. It is preferably added at the stage, most preferably at the stage of nucleation.

In the addition, it may be added in several divided portions, may be added uniformly in the photosensitive silver halide grains, or may be added to the photosensitive silver halide grains. No. 306236, No. 3-167545, No. 4
-76534, 6-110146, 5-273
As described in JP-A No. 683 or the like, it 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. A method of preparing photosensitive silver halide grains by a method of simultaneous mixing of three liquids, a method of adding a required amount of an aqueous solution of a metal compound to a reaction vessel during grain formation, Alternatively, a method of adding and dissolving another photosensitive silver halide grain previously doped with a metal ion or complex ion during preparation of the photosensitive silver halide There is. 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 introduced 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 photosensitive silver halide grains used in the present invention may or may not be desalted after grain formation. When desalting is carried out, it is known in the art such as a noodle method and a flocculation method. It can be desalted by washing with water using a conventional method.

The photosensitive silver halide grains used in the present invention are preferably chemically sensitized. As a preferred chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, and a tellurium sensitization method are well known in the art. 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, and P = Te Compounds having a bond, tellurocarboxylates, Te-organyltellurocarboxylates, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, including Te
Heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used. Compounds preferably used in the noble metal sensitization method include, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, US Pat. No. 2,448,060 and British Patent 618,061
And the like.

Specific compounds for the reduction sensitization method include, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like in addition to ascorbic acid and thiourea dioxide. 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.

In the present invention, the organic silver salt preferably has an average particle size of 1 μm or less and is monodispersed. The average particle size of the organic silver salt means, for example, when the particles of the organic silver salt are spherical, rod-shaped or tabular particles, the diameter when considering a sphere equivalent to the volume of the organic silver salt particles. .

The tabular grains described above preferably have a particle size of 0.01 μm to 0.8 μm, particularly 0.05 μm to 0.5 μm.
μm is preferred. The term “monodispersion” is synonymous with the case of silver halide, and the monodispersion is preferably 1 to 30.

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

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).

[0062]

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.

[0065]

Embedded image

[0066]

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 the 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 (eg, phthalimide); cyclic imides, pyrazolin-5-ones, and quinazolinones (eg, succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and , 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
17643 IV-A (p. 23, December 1978) and Item 1831X (p. 437, August 1978). 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-9-806
The compounds described in No. 79 are preferably used.

In the present invention, a mercapto compound, a disulfide compound, and a thione compound are contained 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. In the present invention, a heteroaromatic ring is preferably used. As the heteroaromatic ring, for example, benzimidazole, naphthymidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, Pyridazine, pyrazine, pyridine, purine, quinoline or quinazolinone. The heteroaromatic ring includes, for example, a halogen atom (eg, Br and Cl), a hydroxy group, an amino group, a carboxy group, an alkyl group (eg, one or more carbon atoms, preferably
Having a substituent selected from the group consisting of those having from 1 to 4 carbon atoms) and alkoxy groups (e.g., having at least one carbon atom, preferably having from 1 to 4 carbon atoms). Is also good. Examples of the mercapto-substituted heteroaromatic compound include 2-mercaptobenzimidazole and 2-mercaptobenzimidazole.
Mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzothiazole, 3-mercapto-1,2,4-triazole,
-Mercaptoquinoline, 8-mercaptopurine, 2,
3,5,6-tetrachloro-4-pyridinethiol,
-Hydroxy-2-mercaptopyrimidine, 2-mercapto-4-phenyloxazole and the like,
The present invention is not limited to these.

In the present invention, a matting agent is preferably contained on the photosensitive layer side, and a matting agent is preferably provided on the surface of the photosensitive material in order to prevent the image after thermal development from being damaged. 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, Swiss Patent No. 3
Silica described in No. 30,158, French Patent No. 1,29
No. 6,995, etc., British Patent No. 1,17
Alkaline earth metals or carbonates such as cadmium and zinc described in 3,181 and the like can be used as a matting agent. As organic substances, US Pat. No. 2,322,03
7, starch derivatives described in Belgian Patent No. 625,451 and British Patent No. 981,198, polyvinyl alcohol described in Japanese Patent Publication No. 44-3643, and Swiss Patent No. 330,158. Polystyrene or polymethacrylate described in U.S. Pat.
Organic matting agents such as polyacrylonitrile described in No. 79,257 and polycarbonate described in U.S. Pat. No. 3,022,169 can be used.

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 of 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 and 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.

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

[0091] A heat-treated plastic support can also 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 a polyester in which all of the polyester components are made of polyethylene terephthalate. 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 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. Preferably, the method described in paragraph [0030] of JP-A-9-50094 is used.
To [0070].

The photothermographic material of the present invention, which forms a photographic image by heat development, 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 promoted by the catalytic action of the latent image generated on the photosensitive 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, European Patent Publication 533,0
08, European Patent Publication 652,473, JP-A-2-2-2
No. 16140, JP-A-4-348339, JP-A-7-
Compounds described in JP-A-191432 and JP-A-7-301890 are preferably used.

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

The light-sensitive 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 for adjusting the gradation.

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)
Materials, Neblette, 8th Edition, Sturge, V.M. Walworth
worth); Shepp Editing, 2nd
Pp. 1969). 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 photosensitive 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,
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.

[0102]

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

<< Preparation of Photosensitive Silver Halide Emulsion A >> Water 9
After dissolving 7.5 g of ossein gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and (98
370 ml of an aqueous solution containing potassium bromide and potassium iodide (equimolar amounts of the above-mentioned silver nitrate) in a molar ratio of / 2) and K ₂ [I
r (NO) Cl ₅ ] was added over 10 minutes by a controlled double jet method while maintaining a pAg of 7.7 at 1 × 10 ⁻⁴ mol per mol of silver. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, the coefficient of variation of the particle size was 11%, and [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, and then 0.1 g of phenoxyethanol was added thereto.
The mixture was adjusted to 5.9 and pAg 7.5 to obtain a photosensitive silver halide emulsion A.

<< 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 fatty acid sodium salt solution.

<< Silver Fatty Acid and Photosensitive Silver Halide Emulsion A >>
Preparation of Photosensitive Emulsion 1 Containing the Same> 15.1 g of the above-mentioned photosensitive silver halide emulsion A was added to the above-mentioned sodium fatty acid solution, and the mixture was adjusted to pH 8.1 with a sodium hydroxide solution.
147 ml of a 1 M silver nitrate solution was added over 7 minutes, and the mixture was further stirred for 20 minutes, and ultrafiltration was performed to remove water-soluble salts. Next, 100 g of an n-butyl acetate solution of polyvinyl acetate (1.2 wt%) was gradually added to the aqueous mixture with stirring, and the mixture was allowed to stand. After forming flocs of the dispersion, water was removed.
Further, water washing and water removal were performed twice. 60 g of a 2.5 wt% solution of polyvinyl butyral (average molecular weight 3000) in methyl ethyl ketone was added with stirring, and then 60 g of polyvinyl butyral (average molecular weight 4000) and methyl ethyl ketone (MEK) were added and mixed, and then 4000 psi (280 kgf / cm ² ) to obtain a photosensitive emulsion 1.

<< Preparation of photosensitive silver halide emulsion B >> A photosensitive silver halide emulsion B was obtained in the same manner as in the preparation of the photosensitive silver halide emulsion A.

<< Preparation of Sodium Salt Solution of Fatty Acid >> A sodium salt solution of a fatty acid was obtained in exactly the same manner as the above-mentioned method for preparing a sodium salt solution of a fatty acid.

<< Silver Fatty Acid and Photosensitive Silver Halide Emulsion B >>
Preparation of Photosensitive Emulsion 2 Containing >> The above fatty acid sodium salt solution was adjusted to pH 8.1 with sodium hydroxide solution, and then 147 ml of a 1M silver nitrate solution was added over 7 minutes to form an organic silver salt. Then, 15.1 g of photosensitive silver halide emulsion B was added, and thereafter photosensitive emulsion 2 was prepared in the same manner as photosensitive emulsion 1.

<< Preparation of Photosensitive Silver Halide Emulsion C >> Water 9
After dissolving 7.5 g of ossein gelatin and 10 mg of potassium bromide in 00 ml and adjusting the temperature to 35 ° C. and the pH to 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and (98
370 ml of an aqueous solution containing potassium bromide and potassium iodide (equimolar amounts of the above-mentioned silver nitrate) in a molar ratio of / 2) and K ₂ [I
r (NO) Cl ₅ ] was added over 10 minutes by a controlled double jet method while maintaining a pAg of 7.7 at 1 × 10 ⁻⁴ mol per mol of silver. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, the coefficient of variation of the particle size was 11%, and [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 repeatedly washed with water five times to remove salt and remove gelatin. The resulting emulsion was sampled and subjected to amino acid analysis. As a result, the residual ratio of gelatin was 4.8%. Thereafter, the emulsion was vacuum-dried for 24 hours to remove water from the emulsion to obtain a photosensitive silver halide emulsion C.

<< Preparation of Fatty Acid Sodium Salt Solution >> A fatty acid sodium salt solution was prepared in the same manner as described above.

<< Silver Fatty Acid and Photosensitive Silver Halide Emulsion C
Preparation of Photosensitive Emulsion 3 Containing A) The above fatty acid sodium salt solution was adjusted to pH 8.1 with a sodium hydroxide solution, and 147 ml of a 1M silver nitrate solution was added thereto over 7 minutes.
An organic silver salt was prepared, further stirred for 20 minutes, and ultrafiltration was performed to remove water-soluble salts. Next, an n-butyl acetate solution of polyvinyl acetate (1.2 wt.
%) Was gradually added, and the mixture was allowed to stand to form a floc of the dispersion. Then, water was removed, followed by washing twice with water and removing water. Polyvinyl butyral (average molecular weight 3000)
2.5% by weight of methyl ethyl ketone (MEK) solution 6
After adding 0 g with stirring, 60 g of polyvinyl butyral (average molecular weight: 4000) and methyl ethyl ketone are further added and mixed to disperse the organic silver salt in the above-mentioned polyvinyl butyral binder, and then to form a photosensitive silver halide. Emulsion C was added in the same number of moles as photosensitive emulsion 1 and stirred for 30 minutes. Subsequently, dispersion was performed at 4000 psi (280 kgf / cm ² ) using a homogenizer to obtain photosensitive emulsion 3.

<< Preparation of Photosensitive Silver Halide Emulsion D >> Photosensitive silver halide emulsion D was prepared in the same manner as photosensitive silver halide emulsion A until grain formation. After grain formation, this emulsion was coagulated and settled using a gelatin coagulant, and repeatedly washed five times with water to remove salts and remove gelatin. After this emulsion 3
While stirring 0.2 g of the solution with a stirrer, 20 g of a solution of polyvinyl acetate in n-butyl acetate (1.2 wt%) was gradually added and allowed to stand. The aqueous phase was removed, the solvent was removed, and then polyvinyl butyral (average molecular weight) 3000) of a 2.5 wt% methyl ethyl ketone solution was added thereto with stirring.
Stirred for minutes. Then 2000psi (140kgf /
cm ² ) to obtain a photosensitive silver halide emulsion D.

<< Preparation of Fatty Acid Sodium Salt Solution >> A fatty acid sodium salt solution was prepared in the same manner as described above.

<< Preparation of Photosensitive Emulsion 4 Containing Fatty Acid Silver and Photosensitive Silver Halide Emulsion D >> The above fatty acid sodium salt solution was adjusted to pH 8.1 with sodium hydroxide solution, and 147 ml of 1M silver nitrate solution was added to 7 Over a minute,
An organic silver salt was prepared, further stirred for 20 minutes, and ultrafiltration was performed to remove water-soluble salts. Next, an n-butyl acetate solution of polyvinyl acetate (1.2 wt.
%) Was gradually added, and the mixture was allowed to stand to form a floc of the dispersion. Then, water was removed, followed by washing twice with water and removing water. Polyvinyl butyral (average molecular weight 3000)
2.5% by weight of methyl ethyl ketone (MEK) solution 6
After adding 0 g while stirring, 52.5 g of polyvinyl butyral (average molecular weight 4000) and methyl ethyl ketone were further added and mixed, and then 4000 psi (28
0 kgf / cm ² ), followed by addition of 1/2 of the photosensitive silver halide emulsion D prepared.
After stirring and mixing for 0 minutes, photosensitive emulsion 4 was obtained.

<< Preparation of PET-undercoated photographic support >> A corona discharge treatment of 8 W / m ² · min. Was performed on both surfaces of a commercially available biaxially stretched heat-fixed 100 μm thick PET film.
On one surface, the following undercoating coating solution a-1 was dried to a thickness of 0.8 μm.
And then dried to form a subbing layer A-1. On the other side, the following antistatic coating subbing coating solution b-1 is applied to a dry film thickness of 0.8 μm and dried. In this way, an antistatic subbing layer B-1 was obtained.

<< 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 << Undercoat coating solution b-1 >> Butyl acrylate (40% by 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) 0.8 g Finishing to 1 liter with water Subsequently, 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 Subbing Upper Layer >> 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 upper layer coating solution b-2 >> (C-4) 60 g Latex solution containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 5 g (C-6) 12 g Polyethylene glycol (weight average molecular weight 600) 6 g Finish to 1 liter with water

[0118]

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[0119]

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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.

<< Preparation of Photosensitive Material >> Sample 1 was prepared by sequentially forming the following layers on the support. The drying was performed at 60 ° C. for 15 minutes. Samples 2 to 4 were prepared by changing photosensitive emulsion 1 to photosensitive emulsions 2 to 4, respectively.

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

Cellulose acetate (10% methyl ethyl ketone 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 monodisperse silica 30 mg / m ² C ₉ H ₁₉ -C ₆ H ₄ -SO ₃ Na 10 mg / m ²

[0124]

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Photosensitive layer 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 emulsion 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) 1.7 ml Antifoggant-2 (10% methanol solution) 1.2 ml 2- (4-chlorobenzoyl) benzoic acid (12% methanol solution) 9.2 ml 2-mercaptobenzimidazole (1% methanol solution) 11 ml tribromomethylsulfoquinoline (5% methanol solution) 17 ml Reducing agent A-4 (20% methanol solution) 29.5 ml Hardening agent H (1% methanol solution) 3 ml

[0127]

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[0128]

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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 (MEK) 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 Tetrachlorophthalic anhydride 170 mg / m ² Matting agent: monodispersity 10% average particle size 4 μm monodisperse silica 70 mg / m ² C ₉ H ₁₉ —C ₆ H ₄ —SO ₃ Na 10 mg / m ² << exposure and development Processing >> The photothermographic material prepared above was exposed with an imager having a semiconductor laser of 810 nm. Thereafter, heat development was performed at 110 ° C. for 15 seconds using an automatic developing machine having a heat drum. At that time, exposure and development were performed in a room conditioned at 23 ° C. and 50% RH.

<< Evaluation of Performance >> After the photosensitive material was exposed with a laser sensitometer equipped with an 820 nm diode, the photographic material was processed (developed) at 120 ° C. for 15 seconds, and the obtained image was evaluated with a densitometer. The result of the measurement was evaluated in terms of Dmin and sensitivity (the reciprocal of the ratio of the exposure amount giving a density higher than Dmin by 1.0). The relative sensitivity was set with the sensitivity of 1 as 100, and Dmin was measured by an optical densitometer in Table 1 below.

[0132]

[Table 1]

As is clear from Table 1, during the formation of the organic silver salt,
Alternatively, the photosensitive silver halide particles are added after the formation of the organic silver salt, and then, compared with a comparative production method of preparing a coating solution by dispersing in a binder solution, the sample produced by the production method of the present invention is: It can be seen that good characteristics with little fog are exhibited.

[0134]

According to the present invention, a photothermographic material having less fog can be obtained, and a method for producing a photothermographic material having a small load on process equipment can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a high-speed stirring type disperser used in the production method of the present invention.

FIG. 2 is a diagram illustrating a dissolver blade used in a high-speed stirring type disperser.

[Explanation of symbols]

 Reference Signs List 1 emulsification dispersion tank 2 impeller 3 vertical axis 4 jacket

Claims (2)

[Claims] 1. A method for producing a photothermographic material using a coating solution containing at least photosensitive silver halide particles and an organic silver salt, wherein the photosensitive silver halide particles and the organic silver salt are separately prepared, And a method for producing a photothermographic material, wherein the photosensitive silver halide particles are added and mixed with an organic silver salt dispersion dispersed in a binder, and then wet-dispersed, followed by coating. 2. A method for producing a photothermographic material using a coating solution containing at least photosensitive silver halide particles and an organic silver salt, wherein the photosensitive silver halide particles and the organic silver salt are the same. A method for producing a photothermographic material, comprising separately dispersing in a solvent and the same binder, then mixing and applying.