JP2002049122A - Heat developable photosensitive material and method of image forming for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having high sensitivity, less liable to fog, ensuring suppressed fogging and sensitivity change in storage and suppressed fog density, fog density change and color tone deterioration particularly due to printout and having good image stability after printout and to provide a method of image forming using the photosensitive material. SOLUTION: The heat developable photosensitive material is obtained by disposing a photosensitive layer containing an organic silver salt, silver halide, a reducing agent, a halogen compound of formula (1) and a halogen compound of formula (2) on a base.

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 an image forming method using the same.

[0002]

2. Description of the Related Art In recent years, in the field of printing plate making and medical treatment, waste liquid caused by wet processing of an image forming material has become a problem in workability, and the amount of treated waste liquid has been reduced from the viewpoint of environmental conservation and space saving. Is strongly desired. Therefore, there is a need for a technique relating to a photothermographic material capable of performing efficient exposure with a laser imagesetter and forming a high-resolution, clear black image. Examples of this type of technology include, for example, U.S. Pat.
487,075 and D.C. Morgan (Dry Silver Photographic Materials)
Photographic Materials) "
(Handbook of ImagingMaterial
ials, Marcel Dekker, Inc. 48, 1991) are known. Since these photosensitive materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

[0003] Such a photothermographic material is usually prepared by dispersing a reducible silver source (for example, an organic silver salt), a catalytically active amount of a photocatalyst (for example, silver halide) and a reducing agent in an organic binder matrix. It is stable at room temperature, but generates silver by an oxidation-reduction reaction between a reducible silver source (acting as an oxidizing agent) and a reducing agent when heated to a high temperature after exposure. 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 organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas and results in the formation of an image.

As a technique for suppressing the fog of the image,
Methods using various halogen compounds have been proposed so far, for example, US Pat. Nos. 3,874,946, 4,459,350, 5,340,712, 4,756,999, Nos. 5,594,143 and 5,594,143, and JP-A-58-59439, 59-46641 and 59-57233.

In Japanese Patent Application Laid-Open No. 56-5535, a polyisocyanate compound is used as a means for improving the physical properties of a photosensitive layer. In Japanese Patent Application Laid-Open No. 6-208193, a polyhalogen compound and an isocyanate compound are used as a means for suppressing fog during storage. A combined photosensitive emulsion technique is disclosed.

[0006] However, the above-mentioned technology has a problem that the effect of preventing fogging is not sufficient, or those having a high effect of preventing fogging cause a significant decrease in sensitivity, and thus need to be improved. Further, when the photosensitive material is stored and aged over time, there has been a problem that fog increases and sensitivity varies. Further, after development, fog rise (printout) caused by exposure to room light or sharksten light, printout density fluctuation during exposure, color tone deterioration due to printout, or image stability after printout is still insufficient. And
It has been desired to develop an antifoggant having no problem.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photothermographic material having high sensitivity, low fog generation, and reduced fog generation and sensitivity fluctuation during storage, especially fog density and its fluctuation due to printout. Another object of the present invention is to provide a photothermographic material in which color tone deterioration is suppressed and image stability after printout is good, and an image forming method using the same.

[0008]

The above object of the present invention is achieved by the following means.

1. A photosensitive layer containing an organic silver salt, a silver halide, a reducing agent, a halogen compound represented by the general formula (1) and a halogen compound represented by the general formula (2) is provided on a support. A photothermographic material comprising:

[0010] 2. 2. The photothermographic material according to the above item 1, wherein in the general formula (2), Ar ₂ is a heteroaryl group containing two or more nitrogen atoms.

3. 3. An image forming method comprising subjecting the photothermographic material according to 1 or 2 to laser exposure and heat development.

Hereinafter, the present invention will be described in detail. The halogen compounds of the general formulas (1) and (2) used in the present invention will be described.

X _{1 to} X ₆ represent a hydrogen atom, a halogen atom or an arbitrary substituent, and at least one of X _{1 to} X ₃ or X _{4 to} X ₆ is a halogen atom. The halogen atom is F, Cl, Br or I, and when two or more are substituted, they may be the same or different. Preferably Cl, B
r, more preferably Br.

Other substituents that can be applied other than a hydrogen atom and a halogen atom are arbitrary and include an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an acyl group, an alkoxycarbonyl group, an aryloxy group, an aryloxycarbonyl group, A carbamoyl group, a sulfamoyl group, an acyloxy group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfonylamino group, a ureido group, a phosphoramide group, a sulfinyl group, a hydroxy group, a heterocyclic group, and the like can be substituted. Of these, electron-withdrawing groups, that is, halogen, trihalomethyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, and sulfamoyl group are preferable. More preferably, all of X _{1 to} X ₆ are halogen atoms, and even more preferably, it is Br.

Ar ₁ and Ar ₂ represent an aryl group or a heteroaryl group. The aryl group is preferably a monocyclic or bicyclic aryl group having 6 to 30 carbon atoms (for example, a phenyl group or a naphthyl group), more preferably a phenyl group or a naphthyl group, further preferably a phenyl group.

The heteroaryl group is a 5- to 6-membered aromatic heterocyclic group which may have a condensed ring containing 1 to 4 nitrogen atoms. Specific heteroaryl groups include imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine , Acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole,
Examples include benzoxazole, benzothiazole, indolenine, tetrazaindene and the like.

Ar ₁ and Ar ₂ can have any substituent. Alkyl group, alkenyl group, aryl group, alkoxy group, acyl group, alkoxycarbonyl group, aryloxy group, aryloxycarbonyl group,
Carbamoyl group, sulfamoyl group, acyloxy group,
Acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group,
A ureido group, a phosphoric acid amide group, a sulfinyl group, a hydroxy group, a heterocyclic group and the like can be substituted. Of these, electron-withdrawing groups, that is, halogen, trihalomethyl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, and sulfamoyl group are preferable. In particular, Ar ₂ is preferably substituted.

A ballast group may be added to the halogen compound of the present invention. The ballast group as used herein refers to a substituent having a total carbon number of 8 or more, preferably 8 to 100, more preferably 8 to 60, and still more preferably 10 to 40. As the ballast group, preferably, an aliphatic hydrocarbon group (for example, an alkyl group, an alkenyl group, an alkynyl group, etc.), an aryl group, a heterocyclic group, and an ether group, a thioether group, a carbonyl group, an amino group, or a sulfonyl group are used. , A phosphonyl group and the like. Also, the ballast group may be a polymer. Specific examples of ballast groups include:
For example, Research Disclosure Magazine (Research)
h Disclosure) 1995 / 2,3793
8, 82-89, JP-A-1-280747, 1-
283548 and the like. The ballast group is preferably one having a total carbon number of 7 to 50, more preferably 10 to 30.

In the general formula (1), L represents a sulfonyl group, a carbonyl group or a sulfinyl group, and a sulfonyl group is most preferred. As Ar ₁ , imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, tetrazole, thiazole, benzimidazole, and benzthiazole are preferable, and pyridine is preferable. , Thiadiazole, quinoline and benzthiazole are more preferred. Specific examples of the compound represented by the general formula (1) are shown below.

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

In the general formula (2), Ar ₂ is preferably a heteroaryl group containing two or more nitrogen atoms. For example, a heteroaryl group containing 2 to 4 nitrogen atoms, such as triazole, tetrazole, thiadiazole, oxadiazole, pyrimidine, and triazine, is more preferable, and a 6-membered group containing 2 to 4 nitrogen atoms, such as pyrimidine and triazine, is more preferable. Saturated heterocycles are preferred. Specific examples of the compound represented by the general formula (2) are shown below.

[0029]

Embedded image

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image

The amount of the halogen compound added is 1 to 1 mol of the total silver atoms contained in the silver halide and the organic silver.
It is 0 ^{-5 to 1} mol, preferably 10 ^-4 to 10 ^-2 mol.

As a technique for suppressing fog of the photothermographic material, various methods using halogen compounds have been proposed. A method using a halogen compound represented by the above general formula (1) or (2) has also been proposed. However, when the halogen compound represented by the general formula (1) or (2) is used alone, the fogging prevention effect is not sufficient, and those having a high fog prevention effect have a problem that a significant decrease in sensitivity is caused. When the photosensitive material is stored and aged,
There were problems that fog increased and sensitivity fluctuated. Further, after development, fog rise (printout) caused by exposure to room light or sharksten light, printout density fluctuation during exposure, color tone deterioration due to printout, or image stability after printout is still insufficient. Met.

The present inventors have found that the above-mentioned general formulas (1) and (2)
It has been found that the above problems can be improved by using a halogen compound in combination. In particular, the rise in fog when the photosensitive material after exposure and development is exposed to light for a long time is suppressed, the color tone of the developed silver is maintained at a pure black tone, and the temporal stability of an image after printout is improved. The mechanism has not been elucidated yet.

The halogen compound of the general formula (2)
The effect was large when r ₂ was a heteroaryl group containing two or more nitrogens. Furthermore, it was favorable when the heteroaryl group was a triazine group.

The photothermographic material of the present invention preferably contains an isocyanate compound in combination with the halogen compound of the present invention, since the object of the present invention can be more highly achieved. As the isocyanate compound, a compound represented by the following general formula (IC) is preferably exemplified.

Formula (IC) (O = C = N−) _v L In the formula (IC), v represents an integer of 1 to 11,
Preferably it is an integer of 3 to 5. L represents a v-valent linking group bonded to the N atom of the isocyanate group. As L,
For example, an alkylene group, an alkenylene group, an arylene group,
Examples thereof include an alkylarylene group and an isocyanuric acid residue. The aryl ring of the arylene group may have a substituent, and preferred substituents are selected from a halogen atom (eg, a bromine atom or a chlorine atom), a hydroxyl group, an amino group, a carboxyl group, an alkyl group and an alkoxy group. Groups.

As the isocyanate compound, an isocyanate compound having at least two isocyanate groups (including an adduct thereof) is preferable.
Specifically, aliphatic diisocyanates, aliphatic diisocyanates having a cyclic group, benzene diisocyanate, naphthalene diisocyanate, biphenyl isocyanate, diphenylmethane diisocyanate,
Examples include triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates, and adducts of these isocyanates with divalent or trivalent polyalcohols. Particularly preferred are aliphatic polyisocyanates, particularly aliphatic polyisocyanates having a cyclic group.

As the isocyanate compound preferably used in the present invention, the following compounds are exemplified.

Ethane diisocyanate, butane diisocyanate, hexane diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylpentane diisocyanate, decane diisocyanate;
ω, ω′-diisocyanate-1,3-dimethylbenzoyl, ω, ω′-diisocyanate-1,2-dimethylcyclohexane diisocyanate, ω, ω-diisocyanate-1,4-diethylbenzol, ω, ω′-diisocyanate-1 , 5-dimethylnaphthalene, ω, ω '
Diisocyanate-n-propylbiphenyl, 1,3
-Phenylene diisocyanate, 1-methylbenzol-2,4-diisocyanate, 1,3-dimethylbenzol-2,6-diisocyanate, naphthalene-1,4
-Diisocyanate, 1,1'-dinaphthyl-2,2 '
-Diisocyanate, biphenyl-2,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-
Diisocyanate, diphenylmethane-4,4'-diisocyanate, 2,2'-dimethyldiphenylmethane
4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate,
4'-diethoxydiphenylmethane-4,4'-diisocyanate, 1-methylbenzol-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-
2,4,6-triisocyanate, diphenylmethane-
2,4,4'-triisocyanate, triphenylmethane-4,4 ', 4'-triisocyanate, tolylene diisocyanate, 1,5-naphthylene diisocyanate
G; dimer or trimer adduct of these isocyanates (eg, hexamethylene diisocyanate dimer)
Mol adduct, hexamethylene diisocyanate 3 mol adduct, 2,4-tolylene diisocyanate 2 mol adduct, 2,4-tolylene diisocyanate 3 mol adduct, etc.); two different kinds selected from these isocyanates Adducts of the above-mentioned isocyanates; and adducts of these isocyanates and divalent or trivalent polyalcohols (preferably polyalcohols having up to 20 carbon atoms, such as ethylene glycol, propylene glycol, pinacol, trimethylolpropane, etc.) (For example, an adduct of tolylene diisocyanate and trimethylolpropane; an adduct of hexamethylene diisocyanate and trimethylolpropane, etc.). Among them, trimers of hexamethylene diisocyanate (1,3,5-triisocyanatohexyl isocyanuric acid) are most preferred.

In the present invention, the isocyanate compound may be contained in the support of the photothermographic material and in any portion on the photosensitive layer side on the support. For example, a support (especially when the support is paper, can be included in the size composition), a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, an undercoat layer, etc. It can be added to any layer, and can be added to one or more of these layers.

The amount of the isocyanate compound added is preferably 0.01 to 20% by mass relative to the total mass of the photosensitive layer.
More preferably, it is 0.5 to 5% by mass.

The following are examples of commercially available isocyanate compounds, but the present invention is not limited thereto. Examples include aliphatic, aromatic and polymeric isocyanates.

IC-1 Desmodu
r) N100, Mobay, aliphatic isocyanate IC-2 Desmodu N3300, Mobay, aliphatic isocyanate IC-3 Mondur TD-80, Mobay, aromatic isocyanate IC-4 Mondue M, Mobay, aromatic Isocyanate IC-5 Montdue MRS, Mobay, Polymer Isocyanate IC-6 Desmodu W, Mobay, Aliphatic Isocyanate IC-7 Papi 27, Dow, Polymer Isocyanate IC-8 Isocyanate T1890, Huls (Hu)
els), aliphatic isocyanate IC-9 octadecyl isocyanate, Aldrich, aliphatic isocyanate The photosensitive silver halide contained in the photosensitive layer of the present invention will be described. The photosensitive silver halide functions as an optical sensor. In the present invention, the average grain size of the photosensitive silver halide grains is preferably small, and the average grain size is 0.1 μm or less, in order to suppress white turbidity after image formation and obtain good image quality. Preferably,
More preferably 0.01 to 0.1 μm, especially 0.02 to
0.08 μm is preferred. The particle size here means
Refers to the diameter (equivalent circle diameter) of a circle having an area equal to that of an individual particle image observed with an electron microscope. The photosensitive silver halide is preferably monodispersed. The term “monodisperse” as used herein means that the coefficient of variation of the particle size distribution determined by the following equation is 40% or less. The coefficient of variation is more preferably at most 30%, particularly preferably at most 20%.

Coefficient of variation of grain distribution = {(standard deviation of grain diameter) / (average of grain diameter)} × 100 The shape of the photosensitive silver halide grains is not particularly limited, but the Miller index (100) plane Is preferably high, and this ratio is preferably at least 50%, more preferably at least 70%, particularly preferably at least 80%. The ratio of the Miller index (100) plane is (11) in the adsorption of the sensitizing dye.
T.1 using the adsorption dependency between the (1) plane and the (100) plane. T
ani, 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 hμm, where the square root of the projected area is the particle diameter rμm.
Means that the aspect ratio = r / h is 3 or more. Among them, the aspect ratio is preferably 3 or more and 50 or less. The particle size is preferably 0.1 μm or less, and more preferably 0.01 to 0.08 μm. Such tabular grains are described in U.S. Pat. Nos. 5,264,337, 5,314,798, and 5,320,958, and can easily obtain desired tabular grains. Can be.

The halogen composition of the photosensitive silver halide is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide. Good. The light-sensitive silver halide emulsion used in the present invention is a P.I. Gla
Chimieet Physique by fkides
Photographique (Paul Monte)
l, 1967); F. Duffin's Ph
autographic Emulsion Chemi
story (published by The Focal Press, 196)
6 years). L. Ma by Zelikman et al
King and Coating Photogra
phy Emulsion (TheFocal Pr
ess, 1964) and the like. That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and the formation of reacting a soluble silver salt and a soluble halide is performed using any one of a one-side mixing method, a double-mixing method, a combination thereof and the like. Is also good.

The photosensitive silver halide used in the present invention preferably contains metal ions belonging to groups 6 to 11 of the periodic table. Examples of the metal of the metal ion include W, Fe, Co, Ni, Cu, Ru, Rh, Pd,
It is preferably at least one selected from Re, Os, Ir, Pt and Au.

These metal ions can be introduced into silver halide in the form of a metal complex or a metal complex ion. As these metal complexes or metal complex ions, hexacoordinate metal complexes represented by the following general formula are preferable.

Formula [ML ₆ ] ^{m In the} above formula, M is a transition metal selected from the elements of Groups 6 to 11 of the periodic table, L is a ligand, and m is 0,-, 2-, 3- or Represents 4-. Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Ligand, nitrosyl, thionitrosyl and the like, preferably aquo, nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different. Particularly preferred examples of M include rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir), and osmium (Os).
It is.

The following are specific examples of the transition metal complex ions. 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) Cl (CN) 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: [R (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 —These metal ions, metal complexes or metal complex ions 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, metal complexes or metal complex ions, generally is suitably 1 × 10 ^-9 ~1 × 10 ^-2 mol per mol of silver halide, preferably 1 × 10 ^{- It is 8} to 1 × 10 ^-4 mol.

The compounds providing these metals are preferably added during silver halide grain formation and incorporated into silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, and chemical ripening Although it may be added at any stage before and after sensitization, it is particularly preferable to add at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, and most preferably. It is added at the stage of nucleation.

In the addition, the compound may be added in several divided portions, and may be added uniformly in 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 a method in which halogen is added. 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.

At the time of addition to the particle surface, 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.

In the present invention, the photosensitive silver halide grains may or may not be desalted after grain formation. However, when desalting is performed, it is known in the art such as a noodle method and a flocculation method. Can be desalted by washing with water.

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. Also, a noble metal sensitization method or a reduction sensitization method of a gold compound, platinum, palladium, iridium compound or the like can be applied.

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 compounds described in JP-A-7-128768 and the like can be used. it can. 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, 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, etc. can be preferably used.

Specific compounds used in the reduction sensitization method include ascorbic acid and thiourea dioxide in addition to, for example,
Stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds and the like can be used. 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 photosensitive layer of the photothermographic material of the present invention may be formed, for example, as described in JP-A-63-159814 and JP-A-60-140335.
No. 63-231437, No. 63-296551
No. 63-304242, No. 63-15245,
U.S. Pat. Nos. 4,639,414 and 4,740,4
No. 55, No. 4,741,966, No. 4,751,
No. 175 and No. 4,835,096. Useful sensitizing dyes for use in the present invention include, for example, Research Disclosure I
Item 17643, Section IV-A (p.
23) or described 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, an argon ion laser light source is disclosed in
162247, JP-A-2-48635, U.S. Pat. No. 2,161,331, West German Patent 936,071
And helium-neon laser light sources described in JP-A-50-62425, JP-A-54-18726 and JP-A-5-18726.
Trinuclear cyanine dyes described in JP-A-9-102229, merocyanines described in JP-A-7-287338,
For the LED light source and the infrared semiconductor laser light source, JP-B-48-42172, JP-B-51-9609 and 55-59
39818, JP-A-62-284343, JP-A-2
Thiacarbocyanines described in No.-105135,
JP-A-59-191 discloses an infrared semiconductor laser light source.
No. 032, tricarbocyanines described in JP-A-60-80841, and 4-quinolines described in formulas (IIIa) and (IIIb) in JP-A-59-192242 and JP-A-3-67242. Dicarbocyanines containing a nucleus and the like are advantageously selected. Further, when the wavelength of the infrared laser light source is 750 nm or more, and more preferably 800 nm or more, in order to cope with a laser in such a wavelength range, Japanese Patent Application Laid-Open Nos. 4-182639 and 5-341432, and JP-B-6-52387. And sensitizing dyes described in U.S. Pat. No. 5,441,866 and JP-A-7-13295 are preferably used. These sensitizing dyes may be used alone, and a combination of sensitizing dyes is often used particularly for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization.

In the case of supersensitization, the photosensitivity is particularly high. If the reducing agent is not deactivated, the printout silver after development tends to be large, and the present invention is particularly effective. In the case of infrared sensitization, the infrared sensitizing dye further has a redox potential capable of reducing silver halide and organic silver salt to some extent, so that the infrared sensitizing dye may be used in a dark place. In the presence of a reducing agent that can reduce the organic silver salt, silver clusters that become fogged silver are easily formed. The generated silver clusters also act as catalyst nuclei and induce fog, so that when stored in a dark place, the storage stability decreases,
Further, when exposed to a light place after development, a phenomenon such as an increase in printout silver occurs. Further, the sensitivity of the infrared sensitive material extends to a heat radiation region outside the range of visible light, so that the present invention is effective in that printout silver due to heat radiation is increased even in a dark place. In particular, in the case of an infrared spectrally sensitized photosensitive material whose sensitivity has been enhanced by a supersensitizer, the effect is large.

These sensitizing dyes may be used alone or in combination, and a combination of sensitizing dyes is often used particularly for supersensitization. Along with the sensitizing dye, the emulsion may contain a dye which does not itself have a spectral sensitizing effect or a substance which does not substantially absorb visible light and exhibits supersensitization. Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are described in RD17643 (December, 1978), page 23, 1V, section J, or JP-B-9-25500, 43.
-4933, JP-A-59-19032 and JP-A-59-1
No. 92242, JP-A-5-341432 and the like.

In the present invention, a heteroaromatic mercapto compound represented by the following formula (M) is preferred as a supersensitizer.

Formula (M) Ar-SM In the formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring having at least one nitrogen, sulfur, oxygen, selenium or tellurium atom. Or a fused heteroaromatic ring. As the heteroaromatic ring or the fused heteroaromatic ring, preferably, benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, triazine, Pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazoline.

A disulfide compound which substantially forms the above-mentioned mercapto compound when contained in a dispersion of an organic acid silver salt and / or silver halide grain emulsion may be used. In particular, a disulfide compound represented by the following general formula (Ma) can be mentioned as a preferred example.

General Formula (Ma) Ar—S—S—Ar In the formula, Ar has the same meaning as in the above general formula (M).

The heteroaromatic ring or fused heteroaromatic ring includes, for example, a halogen atom (eg, Cl, Br,
I), a hydroxy group, an amino group, a carboxyl group, an alkyl group (for example, one or more carbon atoms, preferably
Can have a substituent selected from the group consisting of those having from 1 to 4 carbon atoms) and alkoxy groups (e.g., those having one or more carbon atoms, preferably those having from 1 to 4 carbon atoms). .

The following are examples of mercapto-substituted heteroaromatic compounds. M-1 2-mercaptobenzimidazole M-2 2-mercaptobenzoxazole M-3 2-mercaptobenzothiazole M-4 5-methyl-2-mercaptobenzimidazole M-5 6-ethoxy-2-mercaptobenzothiazole M-6 2,2'-dithiobis (benzothiazole) M-7 3-mercapto-1,2,4-triazole M-8 4,5-diphenyl-2-imidazolethiol M-9 2-mercaptoimidazole M-10 1-ethyl-2-mercaptobenzimidazole M-11 2-mercaptoquinoline M-128-mercaptopurine M-13 2-mercapto-4 (3H) -quinazolinone M-147-trifluoromethyl-4-quinolinethiol M -15 2,3,5,6-tetrachloro-4-pyridine All M-16 4-Amino-6-hydroxy-2-mercaptopyrimidine monohydrate M-17 2-Amino-5-mercapto-1,3,4-thiadiazole M-18 3-Amino-5-mercapto-1, 2,4-Triazole M-19 4-Hydroxy-2-mercaptopyrimidine M-20 2-Mercaptopyrimidine M-21 4,6-Diamino-mercaptopyrimidine M-22 2-Mercapto-4-methylpyrimidine hydrochloride M-23 3-Mercapto-5-phenyl-1,2,4-triazole M-24 2-mercapto-4-phenyloxazole Further, a thiuronium compound as shown below can be suitably used as a supersensitizer.

[0071]

Embedded image

[0072]

Embedded image

The supersensitizer is contained in an emulsion layer containing an organic silver salt and silver halide grains in an amount of 0.001 to 1.0 per mol of silver.
It is preferably used in the range of mol, particularly preferably in the range of 0.01 to 0.5 mol per mol of silver.

The photosensitive layer of the present invention can contain a macrocyclic compound containing a hetero atom. A 9-membered or more macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a hetero atom is preferable,
A 12 to 24 membered ring is more preferred, and an even more preferred one is
It is a 21-membered ring.

Representative compounds include crown ethers, which were synthesized by Pederson shown below in 1967, and a number of which have been synthesized since its unique report.
These compounds are C.I. J. Pederson, Jou
rnal of American chemical
society vol, 86 (2495), 701
7-7036 (1967); W. Gokel, S.M.
H. Korzeniowski, “Macrocycll.
ic polyether synthesis ", Sp
Ringer-Vergal, (1982), edited by Oda, Shono, and Tabushi, "Chemistry of Crown Ethers"
78), Tabushi, "Host-Guest" Kyoritsu Publishing (197)
9), Sasaki, Koga “Synthetic Organic Chemistry” Vol 45
(6), 571-582 (1987).

In the present invention, the organic silver salt is a reducible silver source, and is a silver salt of an organic acid or a heteroorganic acid, especially a long-chain (10 to 30 carbon atoms, preferably 15 to 2 carbon atoms).
5) Silver salts of aliphatic carboxylic acids and nitrogen-containing heterocyclic compounds are preferred. Organic or inorganic complexes in which the ligand has a value of 4.0 to 10.0 as the total stability constant for silver ions are also preferred. Examples of these suitable silver salts include Re
search Disclosure Nos. 17029 and 29996, and include the following.

Silver salts of organic acids such as gallic acid, oxalic acid,
Silver salts such as behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid. Silver carboxyalkylthiourea salts, for example, silver salts such as 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, and aldehydes with hydroxy-substituted aromatic carboxylic acids Silver salts or complexes of polymer reaction products, for example, aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.), hydroxy-substituted acids (for example, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid) )), Silver salts or complexes of thiones, for example, 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione, and 3-carboxymethyl-4 Silver salts or complexes such as -thiazoline-2-thione, imidazole, pyrazole, urazole, 1 2,
4-thiazole and 1H-tetrazole, 3-amino-
Complexes or salts of silver and a nitrogen acid selected from 5-benzylthio-1,2,4-triazole and benzotriazole; silver salts such as saccharin and 5-chlorosalicylaldoxime; and silver salts of mercaptans. Among these, preferred silver salts are silver behenate, silver arachidate or silver stearate.

The organic silver salt can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver. The organic silver salt is described in Japanese Patent Application Laid-Open No. 9-127643, a forward mixing method, a reverse mixing method, and a simultaneous mixing method. Controlled double jet method or the like is preferably used. For example, an organic acid alkali metal salt (eg, sodium hydroxide, potassium hydroxide, etc.) is added to an organic acid to produce an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.), and then controlled by a control double jet. The above-mentioned soap and silver nitrate are added to produce organic silver salt crystals. At that time, silver halide grains may be mixed.

In the present invention, the organic silver salt has an average particle size of 2
It is preferably not more than μm and monodispersed. The average particle size of the organic silver salt means that the particles of the organic silver salt are, for example, spherical,
In the case of rod-shaped or tabular grains, it refers to the diameter of a sphere equivalent to the volume of the organic silver salt grains. The average particle size is preferably from 0.05 to 1.5 μm, in particular from 0.05 to 1.
0 μm is preferred. The term "monodisperse" has the same meaning as in the case of the silver halide, and preferably the coefficient of variation of the size distribution is 1 to 30%.

In the present invention, the tabular grains of the organic silver salt grains preferably account for at least 60% of the total organic silver salt. In the present invention, the tabular grains mean those having an aspect ratio (abbreviated as “AR”) of 3 or more, which is a ratio between the particle diameter and the thickness, which is represented by the following formula.

AR = particle size (μm) / thickness (μm) In order to form the organic silver salt into these shapes, the organic silver salt crystal is dispersed and ground together with a binder, a surfactant and the like by a ball mill or the like. can get. Within this range, a photosensitive material having a high density and excellent image storability can be obtained.

In the present invention, in order to prevent devitrification of the light-sensitive material, the total amount of silver halide and organic silver salt is preferably from 0.5 to 2.2 g per m ² in terms of silver amount. With this range, a high-contrast image can be obtained. The amount of silver halide was 50% by mass relative to the total amount of silver.
Or less, preferably 25% or less, more preferably 0.1 to
Between 15%.

As the reducing agent used in the photothermographic material of the present invention, those known in the art can be used. For example, phenols, polyphenols having two or more phenol groups, naphthol , Bisnaphthols, polyhydroxybenzenes having two or more hydroxyl groups, polyhydroxynaphthalenes having two or more hydroxyl groups, ascorbic acids, 3-pyrazolidones, pyrazoline-5-ones, pyrazolines, phenylenediamine , Hydroxylamines, hydroquinone monoethers, hydroxamic acids, hydrazides, amide oximes, N-hydroxyureas, and the like. More specifically, for example, US Pat.
No. 533, No. 3,679,426, No. 3,67
No. 2,904, No. 3,751,252, No. 3,7
No. 82,949, No. 3,801,321, No. 3,
794,488, 3,893,863, 3,887,376, 3,770,448, 3,819,382, 3,773,512,
No. 3,839,048, No. 3,887,378
No. 4,009,039, No. 4,021,24
0, British Patent No. 1,486,148 or Belgian Patent No. 786,086, and JP-A-50-3
No. 6143, No. 50-36110, No. 50-1160
No. 23, No. 50-99719, No. 50-140113
Nos. 51-51933, 51-23721, 52-84727 and JP-B-51-35851, and the present invention relates to such a known reducing agent. Can be appropriately selected and used. As the selection method, the simplest method is to actually prepare a photothermographic material and evaluate the photographic performance of the photothermographic material to determine the superiority of the reducing agent used.

Among the above reducing agents, when a silver aliphatic carboxylate is used as the organic silver salt, a preferable reducing agent is a polyphenol in which two or more phenol groups are linked by an alkylene group or sulfur, particularly An alkyl group (eg, methyl group, ethyl group, propyl group, t-butyl group, cyclohexyl group, etc.) or an acyl group (eg, acetyl group, propionyl group, etc.) is located at at least one of the positions adjacent to the hydroxy substitution position of the phenol group. Polyphenols in which two or more substituted phenol groups are linked by an alkylene group or sulfur, such as 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,
5,5-trimethylhexane, 1,1-bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, 1,1-bis (2-hydroxy-3,5-di-tert-)
Butylphenyl) methane, (2-hydroxy-3-t-
Butyl-5-methylphenyl)-(2-hydroxy-5
-Methylphenyl) methane, 6,6'-benzylidene-
Bis (2,4-di-t-butylphenol), 6,6 ′
-Benzylidene-bis (2-t-butyl-4-methylphenol), 6,6'-benzylidene-bis (2,4-
Dimethylphenol), 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -2-methylpropane,
1,1,5,5-tetrakis (2-hydroxy-3,5
-Dimethylphenyl) -2,4-ethylpentane, 2,
2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5
U.S. Pat. Nos. 3,589,903 and 4,021,249 or British Patent 1,486,148 and JP-A-51-51933. No. 50-36110, No. 50
Polyphenol compounds described in JP-A-116023, JP-A-52-84727 or JP-B-51-35727, bisnaphthols described in U.S. Pat. No. 3,672,904, for example, 2,2'- Dihydroxy-1,1'-binaphthyl, 6,6'-dibromo-
2,2'-dihydroxy-1,1'-binaphthyl, 6,
6'-dinitro-2,2'-dihydroxy-1,1'-
Binaphthyl, bis (2-hydroxy-1-naphthyl) methane, 4,4'-dimethoxy-1,1'-dihydroxy-2,2'-binaphthyl and the like, and further US Pat. No. 3,80
1,321, sulfonamidophenols or sulfonamidonaphthols, such as 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-
Examples thereof include 4-benzenesulfonamidophenol and 4-benzenesulfonamidonaphthol.

The amount of the reducing agent used in the photothermographic material of the present invention varies depending on the type of the organic silver salt, the reducing agent, and other additives. The suitable amount is from 05 to 10 mol, preferably from 0.1 to 3 mol. Further, within this range, two or more of the above-mentioned reducing agents may be used in combination.

In the photothermographic material of the present invention, it is desirable to use an additive (hereinafter referred to as a color tone agent) called a color tone agent, a color tone imparting agent or an activator toner together with the above-mentioned components. The color tone agent participates in the oxidation-reduction reaction between the organic silver salt and the reducing agent, and has a function of making the resulting silver image dark, particularly black. Examples of suitable toning agents for use in the present invention are Research Disclosure No. 170
No. 29, 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 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) -1-methylethylidene) -2-thio-2,4-oxazolidinedione);
Phthalazinone, phthalazinone derivatives or metal salts of these derivatives (eg, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4- Phthalazine dione); a combination of phthalazinone and a sulfinic acid derivative (for example, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); a combination of phthalazine + phthalic acid; phthalazine (phthalazine And maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivative and its anhydride (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetra Chlorophthalic anhydride) Combinations with at least one compound; quinazolinediones, benzoxazines, naloxazine derivatives; benzoxazine-2,4-diones (eg, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetric -Triazines (e.g.,
2,4-dihydroxypyrimidine) and tetraazapentalene derivatives (e.g., 3,6-dimercapto-1,
4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene). Preferred toning agents are phthalazone or phthalazine.

The binder suitable for the photosensitive layer of the photothermographic material of the present invention is transparent or translucent and generally colorless.
Natural and synthetic polymers and copolymers,
Media for forming a film, for example, gelatin, gum arabic, polyvinyl alcohol, hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinyl pyrrolidone, casein, starch, polyacrylic acid, polymethyl methacrylate, polymethacrylic acid, polyvinyl chloride, Copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinylacetals such as polyvinylformal, polyvinylbutyral, polyesters, polyurethanes, phenoxy resins, polyvinylidene chloride, polyepoxides , Polycarbonates, polyvinyl acetates, cellulose esters, polyamides and the like, which may be hydrophilic or non-hydrophilic. However, among these binders, particularly preferred are water-insoluble polymers such as cellulose acetate, cellulose acetate butyrate and polyvinyl butyral, and among them, polyvinyl butyral is particularly preferred.

In the present invention, the binder amount of the photosensitive layer is preferably 1.5 to 6 g / m ² . More preferably, it is 1.7 to 5 g / m ² . If it is less than 1.5 g / m ² , the density of the unexposed portion will increase significantly and may not be usable.

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 damage to the image after thermal development. Is preferably contained in a mass ratio of 0.5 to 30% based on all binders on the photosensitive layer side.

When a non-photosensitive layer is provided on the opposite side of the photosensitive layer with the support interposed therebetween, it is preferable that at least one layer on the non-photosensitive layer side contains a matting agent, so that the slip property and fingerprint adhesion of the photosensitive material can be improved. For prevention, it is preferable to provide a matting agent on the surface of the photosensitive material, and the matting agent is added in a mass ratio of 0.5 to 4 with respect to all binders of the layer on the side opposite to the photosensitive layer side.
It is preferable to contain 0%.

The material of the matting agent used in the present invention may be either an organic substance or an inorganic substance. For example, as inorganic substances, silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, etc., and alkali described in British Patent No. 1,173,181 etc. An earth metal or a carbonate such as cadmium or zinc can be used as a matting agent. As organic substances, starch described in U.S. Pat. No. 2,322,037, etc.,
Belgian patent 625,451 and British patent 981,
No. 198, etc., JP-B-44-36
No. 43, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, polyacrylonitrile described in U.S. Pat. No. 3,079,257, and U.S. Pat. No. 3,022.
An organic matting agent such as polycarbonate described in JP-A-169 / 169 can be used.

The shape of the matting agent may be either regular or irregular, but 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 to 10 μm, more preferably 1.0 to 8.0 μm. The variation coefficient of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. The variation coefficient of the grain size distribution has the same meaning as in the silver halide grains.

In the photothermographic material of the present invention, the matting agent can be contained in any of the constituent layers, but is preferably a constituent layer other than the photosensitive layer, and more preferably the outermost layer as viewed from the support. It is. The method of adding the matting agent may be a method of dispersing in a coating solution in advance and applying,
A method of spraying a matting agent after the application liquid 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.

The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. In order to control the amount or wavelength distribution of light transmitted to the photosensitive layer, a filter layer may be formed on the same side as or opposite to the photosensitive layer, or a dye or pigment may be contained in the photosensitive layer. As the dye, compounds described in JP-A-8-201959 are preferred. The photosensitive layer may be composed of a plurality of layers, or a high-sensitivity layer and a low-sensitivity layer may be provided for adjusting the gradation, and these layers may be combined. Various additives may be added to any of the photosensitive layer, the non-photosensitive layer and other layers. The photothermographic material of the present invention may contain, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, and a coating aid.

For exposure of the photothermographic material of the present invention, an argon ion laser (488 nm), a He—Ne laser (633 nm), and a red semiconductor laser (670 n) are used.
m), infrared semiconductor laser (780 nm, 820 nm)
And the like are preferably used, but an infrared semiconductor laser is more preferably used from the viewpoint that the laser power is high and the photosensitive material can be made transparent.

In the present invention, it is preferable to use a laser scanning exposure machine in which the angle between the exposure surface of the photosensitive material and the scanning laser beam does not become substantially perpendicular.

Here, "not substantially vertical" means that the angle is most vertical during laser scanning, preferably 55 to 88 degrees, more preferably 60 to 86 degrees.
Degrees, more preferably 65-84 degrees, most preferably 70 degrees.
Means up to 82 degrees.

The beam spot diameter on the exposed surface of the photosensitive material when the laser light is scanned on the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. It is preferable that the spot diameter is small in that the shift angle of the laser incident angle from the perpendicular can be reduced. Note that the lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as occurrence of interference fringe-like unevenness.

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

For the vertical multiplication, a method such as multiplexing, use of return light, or superposition of high frequency is preferable.
In addition, the vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more.
nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

The photothermographic material of the present invention is stable at room temperature, but is developed by heating to a high temperature after exposure. The heating temperature is preferably from 80 to 200 ° C, and more preferably from 100 to 150 ° C. If the heating temperature is lower than 80 ° C., a sufficient image density cannot be obtained in a short time, and if the heating temperature is higher than 200 ° C., the binder is melted and adversely affects not only the image itself but also transportability such as transfer to a roller and a developing machine. Effect. By heating, a silver image is generated by an oxidation-reduction reaction between an organic silver salt (functioning as an oxidizing agent) and a reducing agent. This reaction process proceeds without supply of a processing liquid such as water from the outside.

[0104]

The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

Example 1 [Backing layer] Thickness 1 colored blue with a density of 0.170 (measured with a densitometer PDA-65 manufactured by Konica Corporation)
A corona discharge treatment of 8 w / m ² · min is applied to both sides of a 75 μm polyethylene terephthalate (PET) film,
The backing layer coating solution prepared as described below was applied to one surface thereof by an extrusion coater so as to have a dry film thickness of 3.5 μm, and dried using a dry air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C. After drying for a minute, a backing layer was applied.

(Preparation of Backing Layer Coating Solution) Cellulose acetate butyrate (Eastman Chemical Co.,
AB381-20) 84.2 g, polyester resin (B
4.5 g of Ostic, VitelPE2200B) was added and dissolved. 3.5 g of infrared dye 1 was added to the dissolved solution.
Fluorinated surfactant (Surflon KH40, Asahi Glass Co., Ltd.) 4.5 added and further dissolved in 43.2 g of methanol 4.5
g and 2.3 g of a fluorine-based surfactant (Dainippon Ink Co., Ltd., Megafac F120K) were added, and the mixture was sufficiently stirred until dissolved. Finally, silica (WR Grace, Syloid 64 × 600) dispersed in methyl ethyl ketone at a concentration of 1% by mass with a dissolver-type homogenizer.
0) was added and stirred to prepare a coating solution for the backing layer.

[Photosensitive Layer] (Preparation of Photosensitive Silver Halide Emulsion 1) A1 Phenylcarbamoyl gelatin 88.3 g Compound (A) (10% methanol solution) 10 ml Potassium bromide 0.32 g Finish up to 5429 ml with water B1 0. 67 mol / L aqueous silver nitrate solution 2635 ml C1 potassium bromide 51.55 g potassium iodide 1.47 g Make up to 660 ml with water D1 potassium bromide 154.9 g potassium iodide 4.41 g iridium chloride (1% solution) 0.93 ml E10. 4 mol / L aqueous potassium bromide solution The following silver potential control amount F1 56% acetic acid aqueous solution 16.0 ml G1 1.72 g anhydrous sodium carbonate Finished to 151 ml with water Compound (A): HO (CH ₂ CH ₂ O) _n- [CH ( _{CH 3) CH 2 O] 17} - (CH 2 CH 2 O) m H m + n = 5-7 Using a mixing stirrer described in JP-B-58-58288 and JP-B-58-58289, a quarter of the solution (B1) and the total amount of the solution (C1) were added to the solution (A1) at 45 ° C. and pAg8. 0
While controlling to 9, the addition was performed by the simultaneous mixing method in 4 minutes and 45 seconds to form nuclei. After a lapse of 7 minutes, the solution (B
The rest of 1) and the entire amount of the solution (D1) were added by a double jet method over 14 minutes and 15 seconds while controlling the pAg to 8.09 using the solution (E1) at a temperature of 45 ° C. During mixing,
The pH of the reaction solution was 5.6.

After stirring for 5 minutes, the temperature was lowered to 40 ° C., the whole amount of the solution (F1) was added, and the silver halide emulsion was precipitated. The supernatant was removed, leaving 2000 ml of sedimentation,
After adding 10 L of water and stirring, the silver halide was precipitated again. The supernatant was removed, leaving 1500 ml of the sedimented portion, and 10 L of water was further added. After stirring, the silver halide was sedimented. After removing the supernatant liquid leaving 1500 ml of the sedimented portion, the solution (G1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so as to be 1161 g per mole of silver, whereby photosensitive silver halide emulsion 1 was prepared. This emulsion was cubic silver iodobromide grains having an average grain size of 0.058 μm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

(Preparation of Powdered Organic Silver Salt) In 4720 ml of pure water, 111.4 g of behenic acid, 83.8 g of arachidic acid,
54.9 g of stearic acid were dissolved at 80 ° C. Next, while stirring at a high speed, 540.2 ml of a 1.5 mol / L aqueous sodium hydroxide solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a sodium organic acid solution.

The temperature of the above-mentioned organic acid sodium salt solution was 55
While maintaining the temperature at 0 ° C, KBr was added to the photosensitive silver halide emulsion 1 and 450 ml of pure water, followed by stirring for 5 minutes.

Next, a 1 mol / L silver nitrate solution 760.
6 ml was added over 2 minutes, stirred for another 20 minutes, and the water-soluble salts were removed by filtration. Thereafter, washing with deionized water and filtration are repeated until the conductivity of the filtrate becomes 20 μS / cm, and centrifugal dehydration is performed. Then, hot air drying is performed at 37 ° C. until the mass loss is eliminated. Obtained.

(Preparation of Preliminary Dispersion) Polyvinyl butyral powder (Butvar B-7, manufactured by Monsanto)
9) 14.57 g was dissolved in 1457 g of methyl ethyl ketone, and a dissolver DIS manufactured by VMA-GETZMANN was used.
While stirring with a PERMAT CA-40M type, 500 g of the obtained powdered organic silver salt was gradually added and thoroughly mixed to prepare a preliminary dispersion.

(Preparation of Photosensitive Emulsion Dispersion) Using a GM-2 type pressure homogenizer (manufactured by SMT Corporation), the preliminary dispersion was dispersed in two passes to prepare a photosensitive emulsion dispersion. At this time, the processing pressure during one pass is 27.4.
6MPa and the processing pressure during 2 passes is 54.92MPa
And

Next, the following additives required for preparing the photosensitive layer coating solution were prepared. (Stabilizer liquid) Stabilizer 1 1.00 g Potassium acetate 0.31 g Methanol 10 g (Infrared sensitizing dye liquid) Infrared sensitizing dye 1 41.0 mg 2-Chloro-benzoic acid 2.0 g Compound A 21.0 g MEK 100 g (addition liquid A) 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane 51.0 g 4-methylphthalic acid 3.40 g infrared dye 1 0.22 g MEK 170 g (Preparation of Photosensitive Layer Coating Solution 1) Photosensitive Emulsion Dispersion 100
g and 45 g of MEK were kept at 25 ° C. while stirring, and a solution of antifoggant 1 (10% by mass methanol solution) was added.
65 g was added and the mixture was stirred for 1 hour. Further, 0.84 g of a calcium bromide solution (10% by mass methanol solution) was added, and the mixture was stirred for 20 minutes. Subsequently, after adding 0.70 g of a stabilizer solution and stirring for 10 minutes, 7.90 g of an infrared sensitizing dye solution was added and stirred for 1 hour. Further, 1.50 g of a 1% by mass methanol solution of supersensitizer 1 was added, and the mixture was stirred for 30 minutes. Then, the temperature was lowered to 13 ° C., and the mixture was further stirred for 30 minutes.
While keeping the temperature at 13 ° C, polyvinyl butyral (Mon
15 minutes after adding 26 g of Santo Butvar B-79), 13% by mass of tetrachlorophthalic acid was added.
2.3 g of EK solution were added. While further stirring, 22 mass% ME of isocyanate compound IC-10 was added.
4.5 g of the K solution, 27.0 g of the additive solution A, 10.0 g of a 6.5% by mass MEK solution of the exemplified compound 1-41 of the halogen compound, 6.5 g of 6.5% by mass of the exemplified compound 2-1
K solution, 10.0 g of a 7 mass% MEK solution of phthalazine, and 5 g of a 0.5 mass% MEK solution of potassium p-toluenethiosulfonate were sequentially added and stirred to prepare photosensitive layer coating solution 1. Obtained.

Using the compounds shown in Table 1 in place of the exemplified compounds 1-41 and 2-1, photosensitive layer coating solutions 2 to 20 were obtained in the same manner.

[Surface Protective Layer] (Preparation of Matting Agent Dispersion) Cellulose Acetate Butyrate (Eastman Chemical Company, 7.5 g)
CAB171-15) was dissolved in 42.5 g of MEK,
Among them, calcium carbonate (Specialty M
internals, Super-Pflex200) 5
g, and 8000 r was added with a dissolver-type homogenizer.
The mixture was dispersed at pm for 30 minutes to prepare a matting agent dispersion.

(Preparation of Coating Solution for Surface Protective Layer) MEK865
g of cellulose acetate butyrate (Eastman Chemical, CAB171-
15) 96 g, 4.5 g of polymethylmethacrylic acid (Rohm & Haas Co., Ltd., Paraloid A-21), 1.5 g of vinylsulfone compound, 1.0 g of benzotriazole, 1.0 g of F-based activator (Asahi Glass Co., Surflon KH40) Was added and dissolved. Next, 30 g of a matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

[0118]

Embedded image

[0119]

Embedded image

[Preparation of Photothermographic Material] Each of the above-mentioned coating solutions for the photosensitive layer and the coating solution for the surface protective layer were extruded and simultaneously subjected to multilayer coating using a coater. For the coating, the photosensitive layer was coated in an amount of 1.
9 g / m ² , and the surface protective layer was formed to have a dry film thickness of 2.5 μm. Thereafter, drying was performed for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C. to produce photothermographic materials 1 to 20.

[0121]

[Table 1]

[Exposure and Development Processing] From the emulsion side of the photothermographic material prepared as described above, an exposing machine using a semiconductor laser having a vertical multimode of 800 to 820 nm in wavelength as a light emitting source by superimposed high frequency was used. Exposure by laser scanning was provided. At this time, an image was formed with the angle between the exposure surface of the photosensitive material and the exposure laser beam being 75 degrees.

Thereafter, heat development was performed at 120 ° C. for 15 seconds using an automatic developing machine having a heat drum so that the protective layer of the photothermographic material was brought into contact with the drum surface.

[Evaluation of Sensitivity and Fog] The transmission density of the obtained image was measured, and the sensitivity (the reciprocal of the exposure required to give a density higher by 1.0 than the unexposed portion) and fog were evaluated. Sensitivity is the sample No. The relative sensitivity was expressed as 1 to 1.65. The photothermographic material after coating and drying is
After storage at 75 ° C. and a relative humidity of 75% for 5 days, exposure and development were performed in the same manner, and fog fluctuation and sensitivity fluctuation due to storage for 5 days were measured. And are represented by the difference (increase) from and without storage over time.

[Fog due to printout (PO),
Evaluation of color tone] The light-sensitive material after exposure and development was illuminated at 10,000.
Exposure was performed on a lux light source stand (fluorescent light) for 1, 3, and 20 hours, and fog fluctuation was measured. Represents the difference (increase) from the absence of storage over time. And represents the difference (increase) from the fog of the sample exposed for 1 hour.

The transmission density of the sample irradiated for 20 hours is as follows.
The color tone of silver was evaluated according to the following criteria for 1 ± 0.05.

Evaluation criteria 5: Pure black tone and no yellowness felt 4: Not pure black but almost no yellowness 3: Partially slightly yellowish 2: Slightly yellowish over the entire surface 1: The sample is yellowish at first glance. Further, the sample exposed for 20 hours is exposed to 55 ° C and 75% relative humidity.
% After 7 days storage was expressed as the difference (increase) from the fog of the sample exposed for 20 hours.

Table 2 shows the results.

[0129]

[Table 2]

Table 2 shows that the sample according to the present invention has the following characteristics as compared with the comparative sample. (1) A sample without aging has low fog or a small decrease in sensitivity. (2) A sample with aging has a small increase in fog and a small fluctuation in sensitivity. (3) A fluctuation in fog due to light irradiation after exposure and development is particularly small. Fog fluctuation is small after 3 hours or more of light exposure. (4) There is almost no change in the color tone of the image part after light exposure after exposure and development. (5) The light-exposed sample after exposure and development is fogged by high temperature storage. Small fluctuation.

[0131]

According to the present invention, a heat-developable photosensitive material having high sensitivity and low fog generation and having reduced fog generation and sensitivity fluctuation during storage, in particular, fog density and its fluctuation due to printout, and deterioration of color tone are reduced. It is possible to provide a photothermographic material which is suppressed and has good image stability after printout, and an image forming method using the same.

Claims (3)

[Claims] 1. An organic silver salt, a silver halide,
A reducing agent, a halogen compound represented by the following general formula (1) and
Containing a halogen compound represented by general formula (2)
A photothermographic material comprising an optical layer. Embedded imageIn the general formula (1), X₁, X_TwoAnd X_ThreeIs a hydrogen atom,
Represents a halogen atom or any substituent, but at least
One is a halogen atom. L is a sulfonyl group, carbo
An aryl group or a sulfinyl group;₁Is aryl
Represents a group or a heteroaryl group. General formula (2)
And X_Four, X_Five, X₆And Ar_TwoAre of the general formula (1)
X ₁, X_Two, X_ThreeAnd Ar₁Is synonymous with 2. The photothermographic material according to claim 1, wherein in the general formula (2), Ar ₂ is a heteroaryl group containing two or more nitrogen atoms. 3. An image forming method, comprising subjecting the photothermographic material according to claim 1 to laser exposure and heat development.