JP2003029372A - Heat developable photosensitive material and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having heat and light resistances of an image after development and suppressing printout (fog change and color tone change) particularly on a viewing box whose surface temperature rises to >=40 deg.C and to provide an image forming method using the material. SOLUTION: The heat developable photosensitive material is characterized in that it has a photosensitive layer containing an organic silver salt, silver halide, a reducer and a polyarylsulfone compound of the formula -(Ar-SO2 )n - on a support.

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, and more particularly to a photothermographic material having improved heat resistance and light resistance of an image after development and an image using the same. It relates to a forming method.

[0002]

2. Description of the Related Art In recent years, in the fields of printing and plate making and medical treatment, a waste liquid caused by wet processing of image forming materials has become a problem in terms of workability. Weight loss is strongly desired. Therefore, there is a need for a technology relating to a photothermographic material that can be efficiently exposed by a laser imagesetter and can form a clear black image with high resolution. Examples of this type of technology include, for example, U.S. Pat. No. 3,152,904,
No. 3,487,075 and D.I. Morgan
n) "Dry Silver Photographic Material (Dry Sil
ver Photographic Material
s) "(Handbook of Imaging M
materials, Marcel Dekker, In
c. The photosensitive materials described in page 48, 1991) and the like are known. Since these photosensitive materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

Such a photothermographic material usually contains a reducible silver source (eg organic silver salt), a catalytically active amount of a photocatalyst (eg silver halide) and a reducing agent dispersed in an organic binder matrix. Contains and is stable at room temperature,
When heated to a high temperature after exposure, silver is produced by a redox reaction between a reducible silver source (acting as an oxidizing agent) and the reducing agent. This redox reaction is promoted by the catalytic action of the latent image produced by exposure. The silver produced by the reaction of the organic silver salt in the exposed areas provides a black image, which contrasts with the unexposed areas and forms an image.

However, the above-mentioned photothermographic material has a drawback that undesired formation of silver occurs on a white background portion without an image and fog is formed. As a technique for suppressing the fogging of the image, a method using various halogen compounds has been proposed so far, for example, US Pat. No. 3,874,94.
No. 6, No. 4,459,350, No. 5,340,712
No. 4,756,999, No. 5,594,143
No. 5,594,143, JP-A-58-59439.
Nos. 59-46641 and 59-57233.

Further, JP-A-6-208193 discloses a photothermographic emulsion in which a compound having an isocyanate group and a halogenated antifoggant are used in combination as a means for improving the fog stability during storage.

However, the above-mentioned technique is not sufficiently effective in preventing fog, or those having a high anti-fog effect have problems such as a decrease in sensitivity and thus need to be improved. Further, when an unused light-sensitive material is stored and aged, there are problems that fog is increased and sensitivity is changed.
Further, when the light-sensitive material after development is stored and aged, there are problems that fog is increased and the color tone of the image area is deteriorated.
Especially when observing the developed light-sensitive material on a Schaukasten, intense light exposure of the fluorescent lamp and thermal exposure due to heat generation of the fluorescent lamp (surface temperature of the Schaukasten reaches 40 ° C. or more)
Therefore, there are problems that the fog is increased and the color tone of the image portion is deteriorated.

Further, when processing conditions such as raising the developing temperature in order to shorten the developing time are strengthened, there is a drawback that fog increases. Therefore, development of a fog preventing technique without such a problem has been desired. .

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to prevent fogging after development and the heat resistance and light resistance of images, especially printout on a Schaukasten whose surface temperature has risen to 40 ° C. or more (fogging fluctuation, color tone fluctuation). It is an object of the present invention to provide a photothermographic material in which the occurrence of heat is suppressed and an image forming method using the same.

[0009]

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

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

2. 2. The photothermographic material as described in 1 above, wherein the polyarylsulfone compound represented by the general formula (1) has a cyclic structure.

3. An image forming method, which comprises exposing the photothermographic material according to the above 1 or 2 to a laser and performing heat development.

The present invention will be described in detail below. As a result of earnest research, the present inventor has found that an organic silver salt, a silver halide, a reducing agent and a polyarylsulfone compound represented by the general formula (1) are contained on a support as described in claim 1. The heat resistance and light resistance of the image after development by having the photosensitive layer to be printed, especially printout on the Schaukasten whose surface temperature has risen to 40 ° C or more (fogging change, color tone change)
It has been found that a photothermographic material in which the temperature is suppressed and an image forming method using the same can be obtained. In addition, it was found that the polyarylsulfone compound represented by the general formula (1) preferably has a cyclic structure in order to further exert the effects of the present invention.

The photothermographic material of the present invention comprises a support having thereon a photosensitive layer containing an organic silver salt, a silver halide, a reducing agent and a polyarylsulfone compound represented by the general formula (1). A protective layer is provided on the photosensitive layer, and a backing layer (hereinafter simply referred to as B is provided on the side opposite to the side having the photosensitive layer with respect to the support).
(Also referred to as a C layer), and preferably a protective layer for the BC layer. The photosensitive layer contains an organic silver salt serving as a silver source, a silver halide which may be sensitized, and a reducing agent for developing a silver salt to form a silver image.

(Support) As the support used in the present invention, a support such as polyethylene terephthalate, polyethylene naphthalate or syndiotactic polystyrene is preferred, and biaxially stretched or heat-fixed has high optical isotropy. The thickness is preferably 50 to 400 μm, which has good dimensional stability.

(Polyarylsulfone Compound) The polyarylsulfone compound represented by the general formula (1) used in the present invention will be described.

In the formula, Ar represents an aromatic group or a heterocyclic group which may have a substituent. The aromatic group is preferably a monocyclic or condensed ring aryl group, and examples thereof include a benzene ring and a naphthalene ring. The heterocyclic group is preferably a monocyclic or condensed ring heterocyclic group containing at least one hetero atom selected from nitrogen, sulfur and oxygen atoms, and examples thereof include pyrrolidine, imidazole, tetrahydrofuran, morpholine, pyridine, pyrimidine, quinoline and thiazole. , Benzothiazole, thiophene, furan ring and the like.

These aromatic groups and heterocyclic groups may have a substituent. The substituents are arbitrary, and are 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,
Examples thereof include sulfonylamino group, ureido group, phosphoric acid amide group, sulfinyl group, hydroxy group, carboxyl group, sulfo group, and heterocyclic group. Of these, a hydroxy group, an acyloxy group, a sulfo group and the like are preferable.

N represents a natural number of 2 or more, preferably 3 to 10. The compound may have a linear or cyclic structure, but a cyclic structure is preferred.

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

[0021]

[Chemical 2]

The compound represented by the general formula (1) is water or a suitable organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides).
Although it can be dissolved in water and added to the photosensitive layer, the addition amount is preferably 0.01 to 10 g / m ² , and more preferably 0.
1 to ² g / m ² is preferable.

Examples of the method for producing the compound represented by the general formula (1) include, for example, Japanese Examined Patent Publication Nos. 42-7799 and 45-2.
1318, 46-18146, and JP-A-48-19.
No. 700, No. 59-74123, JP-A-7-1099.
No. 5, No. 7-10996, etc., and can be synthesized with reference to this.

(Silver Halide) The silver halide contained in the photosensitive layer of the present invention will be described. Silver halide functions as an optical sensor. In the present invention, in order to suppress white turbidity after image formation to a low level and to obtain good image quality, it is preferable that the average grain size of silver halide grains is small, and the average grain size is 0.1 μm or less. The thickness is preferably 0.01 to 0.1 μm, more preferably 0.02 to 0.08 μm. The particle size as used herein refers to the diameter of a circle (equivalent circle diameter) having the same area as each particle image observed with an electron microscope. The silver halide is preferably monodisperse. The monodisperse as used herein means that the variation coefficient of the particle size distribution obtained by the following formula is 40% or less. The coefficient of variation is more preferably 30% or less, and particularly preferably 20% or less.

Coefficient of variation of grain distribution = {(standard deviation of grain size) / (average value of grain size) × 100 The shape of silver halide grains is not particularly limited,
The ratio of the Miller index (100) plane is preferably high, and the ratio is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more. Miller index (10
The ratio of the (0) plane is measured by T.W., which utilizes the adsorption dependence of the (111) plane and the (100) plane in the adsorption of the sensitizing dye. Tani,
J. Imaging Sci. , 29, 165 (198
It can be determined by 5).

Another preferred silver halide shape is tabular grain. The tabular grain here means the square root of the projected area with a grain size of rμm and a vertical thickness of hμm.
And the aspect ratio = r / h is 3 or more. Among them, the aspect ratio is preferably 3 to 50. The particle size is preferably 0.1 μm or less,
Furthermore, 0.01 to 0.08 μm is preferable. Such tabular grains are disclosed in US Pat.
No. 314,798, No. 5,320,958 and the like, the intended tabular grains can be easily obtained.

The halogen composition of silver halide is not particularly limited, and silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide,
It may be either silver iodobromide or silver iodide. The silver halide emulsion used in the present invention is described in P. Glafkides
By Chimie et Physique Photo
graphique (published by Paul Montel, 1
967), G. F. Duffin Photogr
apic Emulsion Chemistry
(Published by The Focal Press, 1966),
V. L. Making by Zelikman et al.
and Coating Photographic
Emulsion (The FocalPress)
, 1964) and the like. That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and as a formation for reacting a soluble silver salt and a soluble halogen salt, a one-sided mixing method, a simultaneous mixing method,
Any combination thereof may be used.

The silver halide used in the present invention preferably contains a metal ion belonging to Groups 6 to 11 of the periodic table. As the metal of the metal ion, W, F
e, Co, Ni, Cu, Ru, Rh, Pd, Re, O
It is preferably at least one selected from s, Ir, Pt and Au.

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

General formula [ML ₆ ] ^{m In the} above general formula, M is a transition metal selected from the elements of groups 6 to 11 of the periodic table, L is a ligand, m is 0,-, 2-, 3- or Represents 4-. Specific examples of the ligand represented by L include halides (fluorides, chlorides, bromides and iodides), cyanides, cyanates, thiocyanates, selenocyanates, tellurocyanates, azides and aco. Examples include ligands, nitrosyl, thionitrosyl, and the like, with preference given to ako, nitrosyl, thionitrosyl, and the like. When an aco ligand is present, it preferably occupies one or two of the ligands. L may be the same or different. Particularly preferred specific examples of M include rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) and osmium (Os).
Is.

Specific examples of transition metal complex ions are shown below. 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)] 2Cl _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 the same type of metal and two or more types of different metals may be used in combination. The content of these metal ions, metal complexes or metal complex ions is generally 1 × 10 ⁻⁹ to 1 × 10 ⁻² mol per mol of silver halide, and preferably 1 × 10 ^{−. It is 8} to 1 × 10 ⁻⁴ mol.

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

When the silver halide is added, it may be added dividedly over several times, and it may be added uniformly in the silver halide grains.
-306236, 3-167545, 4-76
No. 534, No. 6-110146, No. 5-273683.
It is also possible to contain the particles having a distribution as described in No. Preferably, it can have a distribution inside the particles.

These metal compounds can be added after being dissolved in water or a suitable organic solvent (eg alcohols, ethers, glycols, ketones, esters, amides). A method of adding an aqueous solution of the powder of 1) or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together 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 When mixed at the same time, it is added as a third aqueous solution to prepare silver halide grains by a three-liquid simultaneous mixing method, a method in which a necessary amount of an aqueous solution of a metal compound is charged into a reaction vessel during grain formation, or a halogen is used. There is a method of adding and dissolving another silver halide grain which has been previously doped with a metal ion or a complex ion at the time of preparing the silver halide. 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 or KCl are dissolved together to a water-soluble halide solution is preferable.

When added to the surface of particles, a necessary amount of an aqueous solution of a metal compound may be added to a reaction vessel immediately after particle formation, during or during physical ripening, or at the time of chemical ripening.

In the present invention, the silver halide grains may or may not be desalted after grain formation. When desalting is carried out, a method known in the art such as a noodle method or a flocculation method is used. It can be desalted by washing with water.

(Chemical Sensitization) The silver halide grains used in the present invention are preferably chemically sensitized. As a preferable chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, or a tellurium sensitization method can be used as well known in the art. Further, a noble metal sensitizing method such as a gold compound, platinum, palladium or iridium compound, or a reduction sensitizing method can be applied.

Known compounds can be used as the compounds preferably used in the sulfur sensitization method, the selenium sensitization method, and the tellurium sensitization method, and the 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, P = Te Compounds having a bond, tellurocarboxylates, Te-organyl tellurocarboxylic acid esters, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, and Te heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium and the like can be used.

The compound preferably used in the noble metal sensitization method is, for example, chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, or US Pat. No. 2,448,060 or British Patent 618. , 061 and the like can be preferably used.

Specific compounds used in the reduction sensitization method include ascorbic acid and thiourea dioxide, as well as, 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 carried out by ripening while maintaining the pH of the emulsion at 7 or higher or pAg at 8.3 or lower. Further, reduction sensitization can be performed by introducing a single addition portion of silver ions during grain formation.

(Sensitizing dye) In the photosensitive layer of the photothermographic material of the present invention, there are, for example, JP-A Nos. 63-159841 and 60-60.
No. 140335, No. 63-231437, No. 63-2
59651, 63-304242, 63-15
245, U.S. Pat. Nos. 4,639,414, and 4,
The sensitizing dyes described in Nos. 740,455, 4,741,966, 4,751,175 and 4,835,096 can be used. Useful sensitizing dyes used in the present invention are, for example, Research Disclo.
Sure Item 17643 IV-A (1978)
December p. 23) or 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, for an argon ion laser source,
JP-A-60-162247, JP-A-2-48635
No. 2, US Pat. No. 2,161,331, West German Patent No. 93
Nos. 5,062,54 and 72,72, for the simple merocyanines and helium neon laser light sources described in JP-A No. 6,071 and JP-A No. 5-11389.
No. 6, 59-102229, the trinuclear cyanine dyes, the merocyanines described in JP-A-7-287338, LED light sources and infrared semiconductor laser light sources, Japanese Patent Publication No. 48-42172. Same as 51-9609
No. 55-39818, JP-A-62-284343.
And the thiacarbocyanines described in JP-A-2-105135, and the tricarbocyanines described in JP-A-59-191032 and JP-A-60-80841 for the infrared semiconductor laser light source, JP-A-59-1922
42, the general formula (IIIa) of JP-A-3-67242,
Dicarbocyanines containing a 4-quinoline nucleus described in (IIIb) are advantageously selected. Further, the wavelength of the infrared laser light source is 750 nm or more, more preferably 800 n
In the case of m or more, in order to deal with a laser having such a wavelength range, JP-A-4-182639 and JP-A-5-341
No. 432, Japanese Patent Publication No. 6-52387, No. 3-10931
No. 5,441,866, Japanese Patent Laid-Open No. 7-13
The sensitizing dyes described in No. 295 and the like are preferably used. These sensitizing dyes may be used alone, and a combination of sensitizing dyes is often used particularly for the purpose of supersensitization. Along with the sensitizing dye, a dye having no spectral sensitizing effect itself or a substance which does not substantially absorb visible light and exhibits supersensitization may be contained in the emulsion.

Since the photosensitivity is particularly high when supersensitized, the printout silver after development tends to be large unless the reducing agent is deactivated, and the present invention is particularly effective. Further, when infrared sensitized, the infrared sensitizing dye further has a redox potential capable of reducing silver halide or an organic silver salt to some extent. In the presence of a reducing agent capable of reducing the organic silver salt of, the silver clusters that become fog silver are likely to be formed. The generated silver clusters also act as catalytic nuclei to induce fogging, which reduces the storage stability when stored in a dark place, and increases the printout silver when placed in a bright place after development. Such phenomenon occurs. Furthermore, since the infrared sensitive material has sensitivity extending to the thermal radiation region outside the visible light range,
The present invention is effective for increasing printout silver due to thermal radiation even in a dark place. In particular, the effect is great in the case of infrared spectrally sensitized light-sensitive materials in which the sensitivity is increased by a supersensitizer.

Useful sensitizing dyes, combinations of dyes exhibiting supersensitization and substances exhibiting supersensitization are RD17643 (197).
Issued December 2012) Page 23, 1V, J, or Japanese Patent Publications 9-25500, 43-4933, JP-A-59-
19032, 59-192242, JP-A-5-3.
No. 41432 and the like.

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

General formula (M) Ar-SM In the formula, M represents a hydrogen atom or an alkali metal atom, and A
r represents a heteroaromatic ring or a condensed heteroaromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. The heteroaromatic ring is preferably benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, Pyridine, purine, quinoline or quinazoline.

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

General formula (Ma) Ar-SS-Ar In the formula, Ar has the same meaning as in the case of the general formula (M).

The heteroaromatic ring is, for example, a halogen atom (for example, Cl, Br, I), a hydroxy group, an amino group, a carboxyl group, an alkyl group (for example, one or more carbon atoms, preferably 1 to Those having 4 carbon atoms) and alkoxy groups (eg one or more carbon atoms,
Preferably, it may have a substituent selected from the group consisting of (having 1 to 4 carbon atoms).

Examples of the mercapto-substituted heteroaromatic compound are shown below. 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-imidazolthiol M-9 2-mercaptoimidazole M-10 1-Ethyl-2-mercaptobenzimidazole M-11 2-mercaptoquinoline M-12 8-mercaptopurine M-13 2-mercapto-4 (3H) -quinazolinone M-14 7-trifluoromethyl-4-quinolinethiol M -15 2,3,5,6-Tetrachloro-4-pyridinethiol 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 (thiuronium compound) Further, the following thiuronium compounds can be preferably used as the supersensitizer.

[0050]

[Chemical 3]

[0051]

[Chemical 4]

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

(Macrocyclic Compound) The photosensitive layer according to the invention may contain a macrocyclic compound containing a hetero atom.
A 9-membered or larger 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 preferable, and a 15- to 21-membered ring is more preferable. is there.

A typical compound is crown ether, which was synthesized by Pederson as described below in 1967, and many compounds 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), G.I. W. Gokel, S .;
H. Korzeniowski, “Macrocycl”
ic polyetherethesis ”, S
pringer-Vergal, (1982), Oda,
Edited by Shono and Tabushi, "The Chemistry of Crown Ether", Chemistry Doujin (1
978), "Host-Guest" edited by Tabushi, Kyoritsu Publishing (197)
9), Sasaki, Koga "Synthetic Organic Chemistry" Vol 45
(6), 571-582 (1987) and the like.

(Polyhalomethane Compound) The photosensitive layer according to the invention may contain a polyhalomethane compound.
The polyhalomethane compound preferably used in the present invention is
A compound having a polyhalomethyl group, wherein the polyhalomethyl group is directly or linked to an aromatic group (eg, phenyl group, naphthyl group, chlorophenyl group, etc.) or heterocyclic group (eg, pyridyl group, furyl group, imidazolyl group and oxazolyl group). Those linked via a group are preferred. Preferred linking groups, -CO- group, -SO ₂
-, - NHSO ₂ -, and the like can be given. Examples of the polyhalomethyl group include a tribromomethyl group, a trichloromethyl group and a dibromomethyl group. The addition amount is from 1 × 10 ⁻⁸ mol to 1 mol of silver halide.
1 × 10 ⁻² mol is preferred. The chemical compound may be added at the time of chemical sensitization or at any time after chemical sensitization and immediately before coating. Specific preferred examples of the polyhalomethane compound preferably used in the present invention are shown below, but the present invention is not limited thereto.

[0056]

[Chemical 5]

(Organic Silver Salt) In the present invention, the organic silver salt is a reducible silver source, and is a silver salt of an organic acid or a hetero organic acid,
Among these, long-chain (C10-30, preferably 15-25) aliphatic carboxylic acids and silver salts of nitrogen-containing heterocyclic compounds are particularly preferable. Organic or inorganic complexes in which the ligand has a value of 4.0 to 10.0 as a total stability constant for silver ions are also preferable. Examples of these suitable silver salts include Research Disclosure No. 17
029 and 29963, including:

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 carboxyalkyl thiourea salts, for example, silver salts such as 1- (3-carboxypropyl) thiourea, 1- (3-carboxypropyl) -3,3-dimethylthiourea, aldehydes and hydroxy-substituted aromatic carboxylic acids Silver salts or complexes of polymer reaction products, for example, aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.), hydroxy-substituted acids (eg salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid) ) A silver salt or complex of a reaction product, a silver salt or a complex of thiones, for example, 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazolin-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 nitrogen acid and silver selected from 5-benzylthio-1,2,4-triazole and benzotriazole, silver salts such as saccharin and 5-chlorosalicylaldoxime, and silver salts of mercaptides. Among these, preferred silver salts are silver behenate, silver arachidate and 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, and it is described in the forward mixing method, the reverse mixing method, the simultaneous mixing method and JP-A-9-127643. The controlled double jet method or the like is preferably used. For example, alkali metal salts of organic acids (eg sodium hydroxide, potassium hydroxide, etc.)
Is added to prepare an organic acid alkali metal salt soap (eg, sodium behenate, sodium arachidate, etc.), and then the soap and silver nitrate are added by a controlled double jet to prepare an organic silver salt crystal. 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 μm or less and monodisperse. With the average particle size of the organic silver salt, particles of the organic silver salt are, for example, spherical,
In the case of rod-shaped or tabular grains, it means the diameter when considering a sphere equivalent to the volume of organic silver salt grains. The average particle size is preferably 0.05 to 1.5 μm, particularly 0.05 to 1.
0 μm is preferable. The monodisperse has the same meaning as in the case of silver halide, and the monodispersity is preferably 1 to 30.

In the present invention, the tabular grains of the organic silver salt grains preferably account for 60% or more of all the organic silver salts. In the present invention, the tabular grains have a grain size to thickness ratio, that is, an aspect ratio (abbreviated as "AR") represented by the following formula of 3 or more.

AR = particle size (μm) / thickness (μm) In order to form the organic silver salt into these shapes, the organic silver salt crystals are dispersed and pulverized by a ball mill or the like together with a binder, a surfactant and the like. can get. Within this range, a light-sensitive material having 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 0.5 g to 2.2 g per m ² in terms of silver amount. Within this range, a high contrast image can be obtained.
Further, the amount of silver halide with respect to the total amount of silver is 50 by mass.
% Or less, preferably 25% or less, more preferably 0.1
Between ~ 15%.

(Reducing Agent) As the reducing agent used in the photothermographic material of the present invention, those known in the art can be used, and examples thereof include phenols and two or more phenol groups. Polyphenols, naphthols, bisnaphthols, polyhydroxybenzenes having two or more hydroxyl groups, polyhydroxynaphthalenes having two or more hydroxyl groups, ascorbic acids, 3-pyrazolidones, pyrazolin-5-ones, pyrazolines Kind,
There are phenylenediamines, hydroxylamines, hydroquinone monoethers, hydrooxamic acids, hydrazides, amidoximes, N-hydroxyureas, and the like. More specifically, for example, US Pat.
No. 5,533, No. 3,679,426, No. 3,6
72,904, 3,751,252, 3,
782,949, 3,801,321, 3,794,488, 3,893,863, 3,887,376, 3,770,448,
No. 3,819,382, No. 3,773,512
No. 3,839,048, No. 3,887,37
No. 8, No. 4,009,039, No. 4,021,2
40, British Patent No. 1,486,148 or Belgian Patent No. 786,086, and Japanese Patent Laid-Open No. 50-
36143, 50-36110, 50-116.
023, 50-99719, 50-14011.
No. 3, No. 51-51933, No. 51-23721,
No. 52-84727 or JP-B-51-35851
There are reducing agents specifically exemplified in each publication, and the present invention can be appropriately selected and used from such known reducing agents. The simplest selection method is to actually make a photothermographic material and evaluate its photographic performance to check the superiority or inferiority of the reducing agent used.

Among the above reducing agents, when an aliphatic carboxylic acid silver salt is used as the organic silver salt, preferred reducing agents include polyphenols 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 acyl group (eg, acetyl group, propionyl group, etc.) is present in at least one position adjacent to the hydroxy-substituted position of the phenol group. Polyphenols in which two or more of the 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-t-butyl-5-methylphenyl) methane, 1,1-bis (2-hydroxy-3,5-di-t-
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, 4,021,249 or British Patent 1,486,148, such as -di-t-butylphenyl) propane, and JP-A-51-51933. , Ibid. 50-36110, ibid. 50
No. 116023, No. 52-84727 or Japanese Patent Publication No. 51-35727, bisnaphthols described in US 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 US Pat. No. 3,80.
Sulfonamide phenols or sulfonamide naphthols as described in 1,321, eg 4-benzenesulfonamidephenol, 2-benzenesulfonamidephenol, 2,6-dichloro-.
4-benzenesulfonamide phenol, 4-benzenesulfonamide naphthol and the like can be mentioned.

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, but generally it is 0. A suitable amount is 05 to 10 mol, preferably 0.1 to 3 mol. Further, within the range of this amount, two or more kinds of the above-mentioned reducing agents may be used in combination.

(Toning Agent) In the photothermographic material of the present invention, an additive (hereinafter referred to as a toning agent) called a toning agent, a toning agent or an activator toner may be used together with the above-mentioned components. desirable. The toning agent has a function of participating in the redox reaction between the organic silver salt and the reducing agent to make the resulting silver image a dark color, especially black. Examples of suitable toning agents for use in the present invention are Research Disclos
Ure 17029, which includes:

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 (for example, N-hydroxy-1,8-naphthalimide); cobalt complex (for example, hexaminetrifluoroacetate of cobalt), mercaptans (for example, 3
-Mercapto-1,2,4-triazole); N- (aminomethyl) aryldicarboximides (e.g.,
N- (dimethylaminomethyl) phthalimide); blocked pyrazoles, isothiuronium (isoth
iuronium) derivative and certain photobleaching agents (eg, N, N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8-
(Combination of (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzothiazole); merocyanine dye (for example, 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 + phthal A combination of acids; phthalazine (including an adduct of 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 tetrachlorophthalic anhydride) in combination with at least one compound; quinazolinediones, benzoxazine, naltoxazine 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). A preferred color tone agent is phthalazone or phthalazine.

(Binder) The binder suitable for the photosensitive layer of the photothermographic material of the present invention is transparent or translucent and generally colorless, and may be a natural polymer, a synthetic polymer or a copolymer, a medium for forming a film, for example, Gelatin, gum arabic, polyvinyl alcohol, hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinylpyrrolidone, casein, starch, polyacrylic acid, polymethylmethacrylate, polymethacrylic acid, polyvinyl chloride, copoly (styrene-maleic anhydride) , Copoly (styrene-acrylonitrile), copoly (styrene-butadiene), polyvinyl acetals such as polyvinyl formal, polyvinyl butyral, polyesters, polyurethanes, phenoxy resins Polyvinylidene chloride, polyepoxides, polycarbonates, polyvinyl acetates, cellulose esters, there is a polyamide or the like, or a non-hydrophilic or hydrophobic. However, among these binders, water-insoluble polymers such as cellulose acetate, cellulose acetate butyrate and polyvinyl butyral are particularly preferable, and polyvinyl butyral is particularly preferable among them.

In the present invention, the binder amount in 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 area may increase significantly and it may not be usable.

(Matting Agent) In the present invention, it is preferable to contain a matting agent on the photosensitive layer side, and it is preferable to dispose a matting agent on the surface of the light-sensitive material in order to prevent scratching of the image after heat development. It is preferable that the matting agent is contained in an amount of 0.5 to 30% by mass with respect to the total binder on the photosensitive layer side.

When a non-photosensitive layer is provided on the side opposite to the photosensitive layer with a support sandwiched between them, it is preferable that at least one layer on the non-photosensitive layer side contains a matting agent, so that the light-sensitive material can have good slipperiness and fingerprint adhesion. For prevention, it is preferable to dispose a matting agent on the surface of the light-sensitive material, and the matting agent is used in a mass ratio of 0.5 to 4 with respect to all binders in the layer opposite to the light-sensitive 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 the inorganic substance, silica described in Swiss Patent No. 330,158, glass powder described in French Patent No. 1,296,995, 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. Examples of the organic matter include starch described in US Pat. No. 2,322,037,
Belgian Patent No. 625,451 and British Patent No. 981,
Starch derivatives described in JP-B No. 198, etc., JP-B-44-36
Polyvinyl alcohol described in No. 43, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, polyacrylonitrile described in US Pat. No. 3,079,257, US Pat. No. 3,022.
Organic matting agents such as polycarbonate described in No. 169 can be used.

The shape of the matting agent may be either a fixed shape or an amorphous shape, but a fixed shape is preferable, and a spherical shape is preferably used. The size of the matting agent is represented by the diameter when the volume of the matting agent is converted into a spherical shape. In the present invention, the particle size of the matting agent refers to the spherically converted diameter.

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 coefficient of variation of the particle size distribution is preferably 50% or less, more preferably 40% or less, and particularly preferably 30% or less. The coefficient of variation of the grain size distribution has the same meaning as in the silver halide grain.

In the photothermographic material of the present invention, the matting agent can be contained in any constituent layer, but is preferably a constituent layer other than the photosensitive layer, more preferably the outermost layer as viewed from the support. Is. The method of adding the matting agent may be a method of previously dispersing and coating in a coating liquid,
A method of spraying the matting agent after applying the coating solution and before the completion of drying may be used. When adding a plurality of types of matting agents, both methods may be used in combination.

Further, the photothermographic material of the present invention includes an isocyanate compound described in Japanese Patent Application No. 2000-44358.
An oxidizing agent, a hydrazine compound, a polyhalomethane compound, a disulfide compound, a crosslinking agent, a phthalazine compound, a phthalic acid compound and a dye described in Japanese Patent Application No. 2001-4996 can 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. A filter layer may be formed on the same side or on the opposite side of the photosensitive layer in order to control the amount or wavelength distribution of light transmitted through the photosensitive layer, or the photosensitive layer may contain a dye or a pigment. As the dye, the compounds described in JP-A 8-201959 are preferred. The photosensitive layer may be composed of a plurality of layers, and a high-sensitivity layer and a low-sensitivity layer may be provided for adjusting gradation and these may be combined. Various additives may be added to any of the light-sensitive layer, the non-light-sensitive layer and other layers. The photothermographic material of the invention may contain, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid and the like.

(Exposure) For exposure of the photothermographic material of the present invention, an argon ion laser (488 nm) and He-N are used.
e laser (633 nm), red semiconductor laser (67
0 nm), infrared semiconductor laser (780 nm, 820 n
m) 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 photothermographic 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 exposed surface of the photothermographic material and the scanning laser light is not substantially perpendicular.

As used herein, the phrase "substantially no vertical" is preferably 55 to 88 degrees, more preferably 60 to 86, as the angle that is the most vertical during laser scanning.
Degrees, more preferably 65 to 84 degrees, most preferably 70 degrees.
It means that the angle is 82 degrees.

The beam spot diameter on the exposed surface of the photothermographic material when scanning the photothermographic material with laser light is preferably 200 μm or less, more preferably 100 μm or less.
μm or less. It is preferable that the spot diameter is smaller because the angle of deviation of the laser incident angle from the vertical can be reduced. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce deterioration of image quality due to reflected light such as occurrence of interference fringe-like unevenness.

Further, it is preferable that the exposure in the image forming method of the present invention is carried out by using a laser scanning exposure machine which emits a scanning laser beam which is vertical multi. Image quality deterioration such as occurrence of interference fringe-like unevenness is reduced as compared with the vertical single mode scanning laser light.

In order to make the vertical multi, it is preferable to use a method of returning light by multiplexing, applying high frequency superposition, or the like. 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.
It is preferable that the thickness is not less than nm. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

(Development) The photothermographic material of the present invention is stable at room temperature, but is developed by heating to high temperature after exposure. The heating temperature is preferably 80 to 200 ° C, and more preferably 100 to 150 ° C. Heating temperature is 8
At 0 ° C. or lower, a sufficient image density cannot be obtained in a short time, and at 200 ° C. or higher, the binder melts, which adversely affects not only the image itself such as transfer to a roller but also the transportability and the developing machine. By heating, a silver image is generated by a redox reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent. This reaction process proceeds without supplying a treatment liquid such as water from the outside. As an apparatus for developing a photothermographic material, JP-A-11-65067 and 11-72 are known.
The devices described in Nos. 897 and 11-84619 can be used.

[0086]

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

Example 1 << Preparation of Backing Layer >> Concentration 0.170 (Konica Corporation)
175 μm thick polyethylene terephthalate (PE, which is colored blue with a densitometer PDA-65 manufactured by PE)
T) Both sides of the film were subjected to a corona discharge treatment of 8 W / m ² · min, and the backing layer coating solution prepared as follows was extruded on one side with a coater to a dry film thickness of 3.5 μm. The coating was applied and dried for 5 minutes using a drying air having a drying temperature of 100 ° C. and a dew point temperature of 10 ° C. to form a backing layer.

(Preparation of Backing Layer Coating Solution) Cellulose acetate butyrate (Eastman Chemical Company, C
AB381-20) 84.2 g, polyester resin (B
4.5 g of Vistel PE2200B (Ostic) was added and dissolved. In the dissolved liquid, 3.5g of infrared dye 1
And a fluorine-based surfactant (Surflon KH40, Asahi Glass Co., Ltd.) dissolved in 43.2 g of methanol.
5 g and 2.3 g of a fluorinated surfactant (Dainippon Ink and Co., Ltd., Megafac F120K) were added and sufficiently stirred until they were dissolved. Finally, silica dispersed in methyl ethyl ketone at a concentration of 1% by a dissolver type homogenizer (WR Grace, Syloid 64 × 600).
0) of 75 g was added and stirred to prepare a backing layer coating liquid.

<< Preparation of Photosensitive Layer >> (Preparation of Silver Halide Emulsion 1) Solution (A1) Phenylcarbamoyl gelatin 88.3 g Compound (A) (10% by mass methanol solution) 10 ml Potassium bromide 0.32 g Water to 5429 ml Finishing solution (B1) 0.67 mol / liter aqueous silver nitrate solution 2635 ml Solution (C1) potassium bromide 51.55 g potassium iodide 1.47 g Finishing with water to 660 ml Solution (D1) potassium bromide 154.9 g potassium iodide 4. 41 g iridium chloride (1% by mass solution) 0.93 ml solution (E1) 0.4 mol / liter potassium bromide aqueous solution Silver potential controlled amount solution (F1) 56% by mass acetic acid aqueous solution 16.0 ml solution (G1) anhydrous carbonic acid Sodium 1.72 g Make up to 151 ml with water Compound (A): HO (C _{2 CH 2 O) n - [} CH (CH 3) CH 2 O] 17 - (CH 2 CH 2 O) m H m + n = 5~7 B No. 58-58288, mixing and stirring according to Nos. 58-58289 Using a machine, add 1/4 amount of the solution (B1) to the solution (A1) and the total amount of the solution (C1) at 45 ° C. and pAg 8.0.
While controlling at 9, the mixture was added for 4 minutes and 45 seconds by the simultaneous mixing method to perform nucleation. After 7 minutes, the solution (B
The rest of 1) and the total amount of the solution (D1) were heated at a temperature of 45 ° C., p
While controlling to Ag 8.09, it was added over 14 minutes and 15 seconds by the double-blending method. During the mixing, the pH of the reaction solution was 5.
It was 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. Remove the supernatant, 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, 10 L of water was further added, and after stirring, the silver halide was precipitated. 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 that the amount was 1161 g per mol of silver, whereby Silver Halide Emulsion 1 was prepared. This emulsion has an average grain size of 0.058 μm and a grain size variation coefficient of 12
%, And the [100] plane ratio was 92%, cubic silver iodobromide grains.

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

The temperature of the fatty acid sodium solution was adjusted to 55
While maintaining at ℃, the above silver halide emulsion 1 and pure water 450
KBr was added to ml and stirred for 5 minutes.

Next, a 1 mol / liter silver nitrate solution 76
0.6 ml was added over 2 minutes, stirred for another 20 minutes, and water-soluble salts were removed by filtration. After that, washing with deionized water and filtration were repeated until the conductivity of the filtrate reached 20 μS / cm, centrifugal dehydration was carried out, and then hot air drying was carried out at 37 ° C. until there was no loss of mass, to obtain the powdered organic silver salt. Obtained.

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

(Preparation of Photosensitive Emulsion Dispersion) Using a GM-2 type pressure homogenizer (manufactured by SMT), each predispersion was dispersed for 2 passes to prepare a photosensitive emulsion dispersion. At this time, the processing pressure in one pass is 27.
46 MPa, the processing pressure during 2 passes is 54.92 MP
a.

Next, the following additive liquids necessary for preparing the photosensitive layer coating liquid 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 (Additive solution 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) 100 g of the photosensitive emulsion dispersion
And 45 g of MEK were kept warm at 25 ° C. with stirring, and a solution of antifoggant 1 (10% by mass methanol solution) 0.6
5 g was added and stirred for 1 hour. Further, 0.84 g of a calcium bromide solution (10% by mass methanol solution) was added and stirred for 20 minutes. Subsequently, 0.70 g of the stabilizer solution was added and stirred for 10 minutes, and then 7.90 g of the infrared sensitizing dye solution was added and stirred for 1 hour.

Further, 1.50 g of a 1% by mass methanol solution of the supersensitizer 1 was added and stirred for 30 minutes, and then the temperature was adjusted to 13
The temperature was lowered to ℃ and the mixture was stirred for another 30 minutes. Polyvinyl butyral (Monsanto, Inc.)
15 minutes after adding 26 g of Butvar B-79),
2.3 g of 13 mass% MEK solution of tetrachlorophthalic acid
Was added. While continuing stirring, 4.5 g of a 22% by mass MEK solution of isocyanate compound IC-10,
27.0 g of the additive liquid A, 6.0 g of a 6.5% by mass MEK solution of the polyhalomethane compound HL3, 9.0 g of a 7% by mass MEK solution of phthalazine, and 0.5% by mass MEK of potassium p-toluenethiosulfonate. 5 g of the solution and the polyarylsulfone compound represented by the general formula (1) shown in Table 1 were sequentially added and stirred to obtain a photosensitive layer coating solution.

<< Preparation of Protective Layer Coating Solution >> While stirring 865 g of MEK, cellulose acetate butyrate (Ea
stman Chemical Company, CAB 171-1
5): 96 g, polymethylmethacrylic acid (Rohm & Haas Company, Paraloid A-21): 4.5 g, vinyl sulfone compound: 1.5 g, benzotriazole: 1.0 g,
F-based activator (Asahi Glass Co., Ltd., Surflon KH40): 1.0
g was added and dissolved. Next, the matting agent dispersion 3 shown below
0 g was added and stirred to prepare a protective layer coating liquid.

[0099]

[Chemical 6]

[0100]

[Chemical 7]

(Preparation of Matting Agent Dispersion) Cellulose Acetate Butyrate (Eastman Chemical)
Company, 7.5 g of CAB171-15) to MEK42.5
g of calcium carbonate (Specia)
Light Minerals, Super-Pfle
x200) (5 g) was added, and the resulting mixture was dispersed with a dissolver type homogenizer at 8000 rpm for 30 minutes to prepare a matting agent dispersion liquid.

<< Preparation of Photothermographic Materials 1 to 5 >> The photosensitive layer coating liquid and the protective layer coating liquid were extruded at the same time to form a multilayer coating. The amount of silver coated on the photosensitive layer is 1.9 g.
/ M ² , and the protective layer was adjusted to have a dry film thickness of 2.5 μm. Then, the photothermographic material 1 was prepared by drying for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C.

Photothermographic materials 2 to 5 were prepared in the same manner except that the compound represented by the general formula (1) was replaced as shown in Table 1 below.

Regarding the obtained photothermographic materials 1 to 5,
Exposure and development were performed as described below, and relative sensitivity, fog, fog fluctuation and color tone fluctuation were evaluated according to the methods described below.

(Exposure and Development Treatment) From the photosensitive layer surface side of the above-mentioned photothermographic material, a wavelength of 800 to 82 is obtained by superposition of high frequencies.
Exposure by laser scanning was performed by an exposure device using a semiconductor laser having a vertical multimode of 0 nm as a light emitting source. At this time, an image was formed by setting the angle between the exposed surface of the photothermographic material and the exposure laser beam to 75 degrees.

After that, an automatic developing machine having a heat drum was used to carry out heat development treatment at 120 ° C. for 15 seconds so that the protective layer of the photothermographic material was in contact with the drum surface.

(Relative Sensitivity, Evaluation of Fog) The transmission density of the obtained image was measured, and the relative sensitivity (1.
0 Relative value where the sensitivity is obtained by the reciprocal of the exposure amount required to give a high density and the sensitivity of the photothermographic material 5 is 1.50)
And the fog was evaluated.

(Fog fluctuation and color tone fluctuation) After exposing and developing the photothermographic material on a light source stand (fluorescent lamp light, surface temperature about 45 ° C.) with an illuminance of 10000 lux, 20
The fog density after the lapse of time was measured. Transmission density 1.1 ±
The silver tone was evaluated according to the following criteria for the 0.05 part.

Evaluation criteria 5: Pure black tone with no yellowness 4: Not pure black, but almost no yellowness 3: Partially slightly yellowish 2: A slight yellowishness is felt on the entire surface 1: At first glance, you can feel yellowishness The results obtained are shown in Table 1.

[0110]

[Table 1]

It is clear from Table 1 that the sample of the present invention has a higher relative sensitivity and lower fog than the comparative sample, and there is less fogging change and color tone change after printing out, and good color tone can be obtained. Is.

[0112]

INDUSTRIAL APPLICABILITY According to the present invention, the heat resistance and light resistance of an image after development, especially printout on a Schaukasten whose surface temperature has risen to 40 ° C. or more (fogging change, color tone change)
It is possible to provide a photothermographic material in which the occurrence of heat is suppressed and an image forming method using the same.

Claims (3)

[Claims] 1. An organic silver salt, silver halide,
A photothermographic material comprising a photosensitive layer containing a reducing agent and a polyarylsulfone compound represented by the following general formula (1). [Chemical 1] (In the formula, Ar represents an aromatic group or a heterocyclic group which may have a substituent. N represents a natural number of 2 or more. The compound may have a linear or cyclic structure.) 2. The photothermographic material according to claim 1, wherein the polyarylsulfone compound represented by the general formula (1) has a cyclic structure. 3. An image forming method, which comprises exposing the photothermographic material according to claim 1 or 2 to laser irradiation and heating and developing the material.