JP2001296632A - Heat-developable photosensitive material and image- recording method, and image-forming method using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-developable photosensitive material, having high sensitivity, low fogging, a good silver tone and satisfactory image preservability, and to provide an image-recording method and an image-forming method each using the photosensitive material. SOLUTION: In the heat-developable photosensitive material, containing at least a non-photosensitive organic silver salt, photosensitive silver halide, a reducing agent capable of reducing the silver ion of the organic silver salt to silver, when it is activated by heat, a binder and a crosslinking agent for the binder, the photosensitive silver halide satisfies the conditions (1) the photosensitive silver halide contains at least one transition metal selected from among the groups 6-11 elements of the periodic table, (2) the amount of hydrophilic colloid contained in the photosensitive silver halide is 40 g or lower per 1 mol silver or lower and (3) the amount of the hydrophilic colloid is >=6×106 g per mol of transition metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photothermographic material which forms an image by heat development, and more particularly, to a photothermographic material having high sensitivity, low fogging, good silver tone and image storability. And an image recording method 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 due to wet processing of image forming materials has become a problem in terms of workability. Weight loss is strongly desired. Therefore, laser
There is a need in the art for photothermographic materials for photographic applications where the imagesetter can be exposed more efficiently with a laser imager and can produce high resolution, sharp black images.

As this technique, for example, US Pat.
No. 2,904, 3,487,075 and D.C. "Dry Silver Photographic" by Morgan
Materials) "(Handbook of I
Managing Materials, MarcelD
ekker, Inc. 48, 1991) is well known. These photosensitive materials are usually
Since development is performed at a temperature of 80 ° C. or higher, it is called a heat development material.

Such a photothermographic material is usually a photothermographic material containing a photosensitive silver halide particle, an organic silver salt, a silver ion reducing agent and a hydrophobic binder on a support. Silver particles are included to impart photosensitivity. In this photosensitive material, a layer is formed by a binder which is softened by heat in order to form an image by causing physical dissolution development in the layer by heat, and an organic silver salt as a silver ion source and a photosensitive halogen are formed in this layer. The composition includes silver halide particles, a reducing agent, and the like. When a photothermographic material having such a configuration is heated, silver halide exposed to light becomes a physical development nucleus, and an organic silver salt serving as a built-in silver ion source reacts with a reducing agent. Development proceeds to form an image. It is characterized in that development proceeds without the supply of reagents, water, etc. from the outside, and that no fixing is performed. Therefore, it is possible to provide the user with a system that is simpler and does not damage the environment.

[0005] This photosensitive material is exposed by a laser imager or a laser imagesetter. Since the exposure by the laser is a short exposure with high illuminance,
Desensitization due to high illuminance failure is a problem. To solve this problem, it is widely known that photosensitive silver halide grains contained in a photothermographic material contain a transition metal complex such as iridium.

On the other hand, when these photothermographic materials are stored unused, there is a problem that fog, sensitivity and gradation change, and fog and color tone also change after storage after development. There is a problem, and although a countermeasure has been proposed, it is practically insufficient, and further improvement has been desired.

[0007]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a photothermographic material having high sensitivity, low fog, and excellent silver tone and image storability. It is to provide a recording method and an image forming method.

[0008]

The above object has been attained by the following means.

It contains at least a non-photosensitive organic silver salt, a photosensitive silver halide, a reducing agent capable of reducing silver ions of the organic silver salt to silver when activated by heat, a binder, and a crosslinking agent for the binder. A photothermographic material wherein the photosensitive silver halide satisfies the following conditions (1) to (3).

(1) The photosensitive silver halide contains at least one transition metal selected from elements of Groups 6 to 11 of the periodic table. (2) Hydrophilic colloid contained in the photosensitive silver halide Is not more than 40 g per mol of silver. (3) The hydrophilic colloid is not less than 6 × 10 ⁶ g per mol of the transition metal, wherein the transition metal is iron, cobalt, ruthenium, rhodium, A metal selected from rhenium, osmium or iridium, a silver ratio of the photosensitive silver halide to the non-photosensitive organic silver salt of 3 to 7%, and all steps of forming silver halide having a pH of 3 to 6. It is preferable to carry out in a range.

An image which is exposed to any one of the above photothermographic materials by a laser beam scanning exposing machine in which an angle between an exposure surface of the photothermographic material and a scanning laser beam does not become substantially perpendicular. A recording method; an image recording method in which a scanning laser beam for recording an image on any one of the above photothermographic materials is exposed by a laser light scanning exposure device having a vertical multi-layer; ~ 200
The object of the present invention has also been achieved by an image forming method of developing by heating at a temperature of ° C.

Hereinafter, the present invention will be described in more detail. First, the photosensitive silver halide will be described.

The silver halide functions as an optical sensor and preferably has a small grain size in order to suppress white turbidity after image formation and to obtain good image quality. The average particle size is 0.1 μm or less, preferably 0.1 μm or less.
It is preferably from 0.1 to 0.1 μm, particularly preferably from 0.02 to 0.08 μm. The shape of the silver halide is not particularly limited, and may be a cubic, octahedral so-called normal crystal or a non-normal crystal spherical,
There are rod-shaped and flat-shaped particles. There is no particular limitation on the silver halide composition, and silver chloride, silver chlorobromide, silver chloroiodobromide,
Any of silver bromide, silver iodobromide and silver iodide may be used.

The amount of silver halide is preferably from 3 to 7%, more preferably from 5 to 7% in terms of silver ratio to the non-photosensitive organic silver salt described below.

The silver halide used in the present invention contains metal ions belonging to groups 6 to 11 of the periodic table. The above metals include W, Fe, Co, Ni, Cu, R
u, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable, and Fe, Co, Ru, Rh, and R are particularly preferable.
e, Os, and Ir.

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, six-coordinate metal complexes represented by the following general formula are preferable.

In the formula [ML ₆ ] ^m , M is a transition metal selected from elements of Groups 6 to 11 of the periodic table, L is a ligand, and m is 0,-, 2-, 3- or 4- Represents Specific examples of the ligand represented by L include halides (fluoride, chloride, bromide and iodide), cyanide, cyanate, thiocyanate, selenocyanate,
Terrocyanate, each ligand of azide and aquo, nitrosyl, thionitrosyl and the like, preferably aquo,
Nitrosyl and thionitrosyl. If an aquo ligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

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

Hereinafter, specific examples of the transition metal complex ion will be shown, but the present invention is not limited thereto.

[0020] 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: [Ru (NS) Cl _5] ^2- 24: _{[Re (NS) Cl 4 (SeCN} ) ] ^2- 25: [Os (NS) Cl (SCN) 4 ] ^2- 26: [Ir (NO) Cl ₅ ] ^2-27 : [Ir (NS) Cl ₅ ] ^2- These metal ions, metal complexes or metal complex ions may be used alone or in combination of two or more of the same and different metals. Good. 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, it may be added in several divided portions, may be uniformly contained in silver halide grains, or may be added to silver halide grains.
-306236, 3-167545, 4-76
No. 534, No. 6-110146, No. 5-273683
As described in No. 2, 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 prepared by using water or a suitable organic solvent (alcohols, ethers, glycols,
Ketones, esters, and amides). Alternatively, an aqueous solution of a metal compound powder or an aqueous solution in which the metal compound is dissolved together with sodium chloride and potassium chloride may be added during particle formation. A silver halide solution is added to a water-soluble silver salt solution or a water-soluble halide solution, or is added as a third aqueous solution when the silver salt solution and the halide solution are mixed at the same time. A method for preparing grains, 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 another silver halide grain previously doped with metal ions or complex ions during silver halide preparation. There is a method of adding and dissolving. 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 is dissolved together with sodium chloride and potassium chloride to a water-soluble halide solution is preferable.

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

The photosensitive silver halide grains may or may not be desalted after grain formation. When desalting is performed, washing with a water known method such as a noodle method or a flocculation method may be used. To desalinate.

The method for preparing a silver halide emulsion containing photosensitive silver halide grains is described in, for example, P.S. Glafide
s author; Chimie et Physique Pho
T. graphique (Paul Montel, 1967); F. By Duffin; Photo
optic Emulsion Chemist
ry (The Focal Press, 1966)
Year), V. L. By Zelikman et al; Ma
King and Coating Photogra
phi Emulsion (The Focal P
Ress., 1964), etc.
These can be used to prepare a silver halide emulsion.

That is, any of an acidic method, a neutral method, an ammonia method and the like may be used, and a method of reacting a soluble silver salt with a soluble halide salt may be any of a one-side mixing method, a simultaneous mixing method, a combination thereof and the like. May be used. Typically, a silver halide emulsion is prepared by mixing a silver salt aqueous solution and a halide aqueous solution in a protective colloid (a hydrophilic colloid such as gelatin is used) serving as a reaction mother liquor, and performing nucleation and crystal growth. The double jet method is generally used as a method for adding an aqueous halide solution or an aqueous silver salt solution.

Among these, the controlled double jet method of mixing the components while controlling the pAg and pH to perform the nucleation and crystal growth is representative. Also, first,
After preparation (nucleation) of the seed particles, various variations are included, such as a method in which the growth is carried out in two steps such as continuing under the same conditions or under different conditions (crystal growth or ripening). In short, it is well known in the art that in the mixing step in a protective colloid aqueous solution, the crystal habit and size are variously controlled by defining the mixing conditions of the silver salt aqueous solution and the halide aqueous solution.
Subsequent to these mixing steps, a desalting step of removing excess salts from the prepared emulsion is performed. In the desalination process,
A flocculation method is well known, in which a flocculant is added to a prepared silver halide emulsion to coagulate and precipitate silver halide grains together with gelatin as a protective colloid, and this is separated from a supernatant containing salts. The supernatant is removed by decantation, and further, dissolution, flocculation, and decantation are repeated in order to remove excess salts contained in the gelatin coagulated matter containing the coagulated and precipitated silver halide particles. Also, a method of removing soluble salts by an ultrafiltration method is well known. This is a method of using a ultrafiltration membrane to remove unnecessary salts having a low molecular weight through a synthetic membrane through which large particles such as silver halide particles and gelatin and molecules having a large molecular weight do not pass. .

In the present invention, the amount of the hydrophilic colloid contained in the photosensitive silver halide is not more than 40 g, preferably not more than 35 g per mol of silver.

Further, in the present invention, silver halide grains
Selected from elements of groups 6 to 11 of the periodic table
6 × hydrophilic colloid per mole of transition metal
10 ⁶g or more.

That is, the content of the hydrophilic colloid and the transition metal contained in the photosensitive silver halide is selected to satisfy the above conditions.

The photosensitive silver halide prepared by the above-mentioned various methods includes, for example, sulfur-containing compounds, gold compounds,
Platinum compounds, palladium compounds, silver compounds, tin compounds,
Chemical sensitization can be performed by a chromium compound or a combination thereof. The method and procedure of the chemical sensitization are described in, for example, U.S. Pat. No. 4,036,650, British Patent 1,518,850, JP-A-51-2430, JP-A-51-78319, and JP-A-51-81124. It is described in. Further, when a part of the organic silver salt is converted into a photosensitive silver halide by a silver halide forming component, as described in U.S. Pat. No. 3,980,482, a low molecular weight is required to achieve sensitization. May be allowed to coexist.

In a further preferred embodiment of the present invention, the pH in all steps of forming the photosensitive silver halide is from 3 to 6, preferably from 4 to 6.

The concentration distribution of the transition metal in the silver halide grains can be determined by gradually dissolving the grains from the surface to the inside and measuring the content of the transition metal in each part. Specific examples include the method described below.

Prior to the determination of the transition metal, the silver halide emulsion is pretreated as follows. First, 50 ml of a 0.2% actinase aqueous solution is added to about 30 ml of the emulsion, and the mixture is stirred at 40 ° C. for 30 minutes to perform gelatin decomposition. This operation is repeated five times. After centrifugation, 5 times with 50 ml of methanol, 1
Washing is repeated twice with 50 ml of mol / L nitric acid and five times with ultrapure water, and after centrifugation, only silver halide is separated. The obtained silver halide grain surface is treated with an aqueous ammonia solution or a pH-adjusted ammonia (ammonia concentration and p
H varies depending on the type and amount of silver halide). As a method for dissolving the extreme surface of silver bromide grains among silver halides, about 2% of silver halide can be dissolved to about 3% from the grain surface by using about 10% aqueous ammonia solution (20 ml) for 2 g. . At this time,
The amount of silver halide dissolved is determined by centrifuging the aqueous ammonia solution after dissolving the silver halide and the silver halide, and measuring the amount of silver present in the obtained supernatant by a high frequency induction plasma mass spectrometer ( ICP-MS), high frequency induction plasma emission spectrometry (ICP-AES), or atomic absorption. From the difference between the amount of metal contained in the silver halide after surface dissolution and the total amount of transition metal of silver halide not dissolved, the amount of transition metal per mol of silver halide existing in about 3% of the grain surface is determined. be able to.
As a method for quantifying a transition metal, an aqueous solution of ammonium thiosulfate, an aqueous solution of sodium thiosulfate, or an aqueous solution of potassium cyanide, and a matrix-matched ICP
-MS method, ICP-AES method, or atomic absorption method. Among them, potassium cyanide as a solvent and ICP-MS (FISON Element) as an analyzer
al Analysis), about 40 mg of silver halide is dissolved in 5 ml of a 0.2 mol / L potassium cyanide solution, and then an internal standard element Cs solution is added to 10 ppb, and the solution is made up to 100 ml with ultrapure water. The fixed volume is used as the measurement sample. Then, the transition metal in the measurement sample is quantified by ICP-MS using a calibration curve obtained by combining a matrix using transition metal-free silver halide. At this time, the exact amount of silver in the measurement sample can be determined by ICP-AES or atomic absorption of the measurement sample diluted 100 times with ultrapure water. After dissolving such a grain surface, washing the silver halide grains with ultrapure water, and repeating dissolution of the grain surface in the same manner as described above,
The amount of the transition metal in the silver halide grains can be determined.

By combining the above transition metal determination method with the well-known particle observation using an electron microscope, the transition metal doped in the peripheral region of the silver halide grains used in the present invention can be determined. .

When a plurality of metals are used as the transition metal, the content of the above-mentioned transition metal is represented by mol
Count the number.

In the present invention, the organic silver salt is a reducible silver source, and is preferably 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 Research Discl.
osure, hereinafter abbreviated as RD) 17029 and 2996
3, and the following are mentioned.

Silver salts of organic acids such as gallic acid, oxalic acid, behenic acid, stearic acid, arachidic acid, palmitic acid,
Silver salts such as lauric acid. A carboxyalkylthiourea salt of silver, for example 1- (3-carboxypropyl) thiourea;
Silver salts such as 1- (3-carboxypropyl) -3,3-dimethylthiourea. Of aldehydes with hydroxy-substituted aromatic carboxylic acids [aldehydes (formaldehyde, acetaldehyde, butyraldehyde, etc.) and hydroxy-substituted acids (salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, etc.)] Silver salts or complexes of polymer reaction products. Silver salts or complexes of thiones, for example, silver salts or complexes such as 3- (2-carboxyethyl) -4-hydroxymethyl-4-thiazoline-2-thione and 3-carboxymethyl-4-thiazoline-2-thione. . Imidazole, pyrazole, urazole, 1,2,2
4-thiazole and 1H-tetrazole, 3-amino-
A complex or salt 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 mercaptides.

Among them, preferred silver salts are silver behenate, silver arachidate or silver stearate.

The organic silver salt compound can be obtained by mixing a water-soluble silver compound and a compound which forms a complex with silver, and includes a normal mixing method, a reverse mixing method, a simultaneous mixing method, and a method described in JP-A-9-12764.
A controlled double jet method as described in No. 3 is preferably used.

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

The organic silver salt of the present invention 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 organic silver salt grains. The average particle size is more preferably from 0.05 to 1.5 μm, particularly preferably from 0.0 to 1.5 μm.
5 to 1.0 μm is preferred. Monodispersion has the same meaning as that of silver halide, and preferably has a monodispersity of 1 to 30.
It is.

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

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

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

It is preferable that the tabular organic silver salt particles are preliminarily dispersed together with a binder, a surfactant and the like, if necessary, and then dispersed and pulverized with a media disperser or a high-pressure homogenizer. For the preliminary dispersion, a general stirrer such as an anchor type or a propeller type, a high-speed rotation centrifugal radiation type stirrer (dissolver), and a high-speed rotation shear type stirrer (homomixer) can be used.

As the above-mentioned media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill and a vibrating ball mill, a bead mill, an attritor, and a basket mill as a medium stirring mill can be used, and a high-pressure homogenizer can be used. Various types can be used, such as a type that collides with a wall, a plug, or the like, a type that divides a liquid into a plurality of liquids and then collides the liquids at a high speed, and a type that passes a thin orifice.

Ceramics used when dispersing media
As ceramics used for beads, for example, Al
_TwoO_Three, BaTiO_Three, SrTiO_Three, MgO, ZrO, B
eO, Cr_TwoO_Three, SiO_Two, SiO_Two-Al_TwoO_Three, Cr_Two
O_Three-MgO, MgO-CaO, MgO-C, MgO-
Al_TwoO_Three(Spinel), SiC, TiO_Two, K_TwoO, Na
_TwoO, BaO, PbO, B_TwoO_Three, SrTiO_Three(Titanic acid
Strontium), BeAl_TwoO_Four, Y_ThreeAl_FiveO₁₂, Zr
O_Two-Y_TwoO_Three(Cubic zirconia), 3BeO-Al_TwoO
_Three-6SiO_Two(Synthetic emerald), C (synthetic diamond)
C), Si_TwoOn-nH_TwoO, silicon nitride, yttrium stable
Zirconia fluoride, zirconia reinforced alumina and the like are preferred.
Impurity generation due to friction with beads and disperser during dispersion
Yttrium-stabilized zirconia
A, zirconia reinforced alumina (containing these zirconia
Ceramics, which will hereinafter be abbreviated as zirconia)
It is preferably used.

In the apparatus used for dispersing the tabular organic silver salt particles, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond is used as a material of a member that comes into contact with the organic silver salt particles. It is preferable to use zirconia.

In carrying out the above dispersion, the binder concentration is preferably 0.1 to 10% of the mass of the organic silver, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion to the main dispersion. In addition, preferable operating conditions of the main dispersion include:
For example, when a high-pressure homogenizer is used as the dispersing means, it is preferable that the pressure is 29.42 to 98.06 MPa and the number of operations is two or more. When a media dispersing machine is used as the dispersing means, a preferable condition is a peripheral speed of 6 to 13 m / sec.

Further, zirconia can be used for a part of beads or members, and can be mixed into a dispersed emulsion at the time of dispersion.
This is preferable and effective in terms of photographic performance. Zirconia fragments may be added later to the dispersion emulsion, or may be added in advance during the preliminary dispersion. Although a specific method is not particularly limited, for example, by circulating methyl ethyl ketone through a bead mill filled with zirconia beads, a high-concentration zirconia solution can be obtained. It may be added at a preferable time and at a preferable concentration.

Examples of the reducing agent used in the photothermographic material of the present invention include generally known reducing agents, such as phenols, polyphenols having two or more phenol groups, naphthols, bisnaphthols, Polyhydroxybenzenes having two or more hydroxyl groups, polyhydroxynaphthalenes having two or more hydroxyl groups, ascorbic acids, 3-pyrazolidones, pyrazoline-5-
Ons, pyrazolines, phenylenediamines, hydroxylamines, hydroquinone monoethers, hydroxamic acids, hydrazides, amide oximes,
There are N-hydroxyureas and the like, and more specifically, U.S. Patent Nos. 3,615,533, 679,426, 3,672,904, 3,751,252, and 3,782. 949, 3,801,321, 3,794,488, 3,893,863, 3,887,376, 3,770,448, 3,819,382 3,773,512, 3,839,048, 3,887,378, 4,009,039, 4,021,240, British Patent 1,486,148, Belgian Patent 786,08
No. 6, JP-A-50-36143 and JP-A-50-36110
No., 50-116023, 50-99719,
Nos. 50-140113, 51-51933, 5
No. 23721, No. 52-84727, Japanese Patent Publication No. 51
There is a reducing agent specifically exemplified in -35851, which can be appropriately selected from such known reducing agents. As the selection method, the simplest method is to actually prepare a photothermographic material and evaluate the photographic performance to determine the superiority of the reducing agent used.

Among the above reducing agents, when an aliphatic silver carboxylate 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. In particular, two or more phenol groups in which an alkyl group (methyl, ethyl, propyl, t-butyl, cyclohexyl, etc.) or an acyl group (acetyl, propionyl, etc.) is substituted on at least one of the positions adjacent to the hydroxy substitution position of the phenol group. 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-tert-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-
U.S. Pat. Nos. 3,589,903 and 4,021, such as hydroxy-3,5-di-tert-butylphenyl) propane;
249 or British Patent 1,486,148 and JP-A-51-51933, 50-36110, and 5
Polyphenol compounds described in JP-A Nos. 0-116023, 52-84727 and 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 '
-Sulfonamidophenol or sulfonamidonaphthols as further described in U.S. Pat. No. 3,801,321, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro- Examples thereof include 4-benzenesulfonamidophenol and 4-benzenesulfonamidonaphthol.

The amount of the reducing agent used varies depending on the type of the organic silver salt and the reducing agent, and other additives, but is generally 0.05 to 10 mol, preferably 0 to 10 mol, per mol of the organic silver salt. .1 to 3 moles are suitable. 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 called a color tone agent, a color tone imparting agent or an activator toner (hereinafter, referred to as a color tone agent) together with the above-mentioned components. . The color tone agent has a function of participating in the oxidation-reduction reaction between the organic silver salt and the reducing agent to make the resulting silver image dark, particularly black. An example of a suitable toning agent is RD17029
And includes the following:

Imides (phthalimide and the like); cyclic imides, pyrazolin-5-ones, and quinazolinones (succinimide, 3-phenyl-2-pyrazolin-5-one, 1-phenylurazole, quinazoline and 2,4-
Naphthalimides (such as N-hydroxy-1,8-naphthalimide); cobalt complexes (such as hexamine trifluoroacetate of cobalt); and mercaptans (such as 3-mercapto-1,2,4-).
N- (aminomethyl) aryldicarboximides (such as N- (dimethylaminomethyl) phthalimide); combinations of blocked pyrazoles, isothiuronium derivatives and certain photobleaches (N,
N'-hexamethylene (1-carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate) and 2- (tribromomethylsulfonyl) benzo Merocyanine dye (3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene) -2-thio-2,4) -Oxazolidinedione, etc.);
Phthalazinone, phthalazinone derivatives or metal salts of these derivatives (4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazine A combination of phthalazinone and a sulfinic acid derivative (eg, 6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone + sodium p-trisulfonate); a combination of phthalazine + phthalic acid;
Phthalazine (including adducts of phthalazine) and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivatives and their anhydrides (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and A combination with at least one compound selected from tetrachlorophthalic anhydride and the like; quinazolinediones, benzoxazine, and naltoxazine derivatives; benzoxazine-2,4-diones (1,3-benzoxazine-2,
Pyrimidines and asymmetric triazines (such as 2,4-dihydroxypyrimidine); and tetraazapentalene derivatives (such as 3,6-dimercapto-1,4-).
Diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene and the like). Preferred toning agents are phthalazone or phthalazine.

Binders suitable for photothermographic materials are transparent or translucent and generally colorless, and include natural polymers, synthetic polymers and copolymers, and other film-forming media such as gelatin, gum arabic, polyvinyl alcohol, and hydroxyethyl cellulose. , Cellulose acetate, cellulose acetate butyrate, polyvinylpyrrolidone, casein, starch, polyacrylic acid, polymethyl methacrylate, polymethacrylic acid, polyvinyl chloride, copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly ( Styrene-butadiene), polyvinyl acetals such as polyvinyl formal, polyvinyl butyral, polyesters,
There are 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 it is preferable to arrange a matting agent on the surface of the light-sensitive material in order to prevent the image after thermal development from being damaged. It is preferable that the matting agent is 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, and that the light-sensitive material has slipperiness and fingerprint adhesion. For the 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 40% with respect to all binders in the layer on the side opposite to the photosensitive layer side.
It is preferred to contain.

The material of the matting agent used may be either an organic substance or an inorganic substance. As inorganic materials, Swiss Patent 3
Silica described in No. 30,158, French Patent 1,29
Glass powder described in US Pat.
Alkaline earth metals or carbonates such as cadmium and zinc described in 3,181 and the like can be used as a matting agent. Examples of organic substances include starch described in U.S. Pat. No. 2,322,037, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, etc., and polyvinyl described in Japanese Patent Publication No. 44-3643. alcohol,
Polystyrene or polymethacrylate described in Swiss Patent 330,158 and the like, US Patent 3,079,2
Polyacrylonitrile described in US Pat.
A matting agent such as polycarbonate described in No. 022,169 can be used.

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere. The matting agent used in the present invention has an average particle size of 0.5 to 10 μm
And more preferably 1.0 to 8.0.
μm. Also, as the variation coefficient of the particle size distribution,
It is preferably 50% or less, more preferably 4% or less.
The matting agent is 0% or less, particularly preferably 30% or less.

Here, the variation coefficient of the particle size distribution is a value represented by the following equation. (Standard deviation of particle size / average value of particle size) × 100 The matting agent can be contained in any constituent layer, but in order to achieve the object of the present invention, it is preferable to use a constituent layer other than the photosensitive layer. Yes, more preferably the outermost layer as viewed from the support. The method of adding the matting agent may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed before the drying is completed after the coating solution is applied. When a plurality of types of matting agents are added, both methods may be used in combination.

The photothermographic materials of the present invention include, for example, JP-A-63-159814, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, and JP-A-6-259561.
3-304242, 63-15245, U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, 4,835,096 The sensitizing dyes described in No. 1 can be used.

Useful sensitizing dyes are, for example, RD1764
3, page 23, section IV-A (December 1978). In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected.

For example, for an argon ion laser light source, see JP-A-60-162247 and JP-A-2-4863.
5, US Patent No. 2,161,331, West German Patent 93
For simple merocyanines and helium neon laser light sources described in US Pat. No. 6,071 and Japanese Patent Application No. 3-189532, JP-A-50-62425 and JP-A-54-187.
JP-B-48-42172 discloses trinuclear cyanine dyes described in JP-A Nos. 26 and 59-102229, merocyanines described in Japanese Patent Application No. 6-103272, LED light sources and infrared semiconductor laser light sources. Id. 51-9609
No. 55-39818, JP-A-62-284343.
Thiacarbocyanines described in JP-A-2-105135, and tricarbocyanines described in JP-A-59-19032 and 60-80841 for an infrared semiconductor laser light source; JP-A-59-1922
No. 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 n
m or more preferably 800 nm or more, in order to cope with a laser in such a wavelength range, Japanese Patent Application Laid-Open No.
Nos. 182639, 5-341432, 6-5
No. 2387, No. 3-10931, U.S. Pat.
Sensitizing dyes described in JP-A No. 1,866 and JP-A-7-13295 are preferably used.

These sensitizing dyes may be used alone.
In particular, combinations of sensitizing dyes are frequently used 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.

The photothermographic material of the present invention has at least one photosensitive layer on a support. Although only a photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. 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 the photosensitive layer or on the opposite side, or a dye or pigment may be contained in the photosensitive layer. Is also good. 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 may be combined.

Various additives may be added to any of the photosensitive layer, the non-photosensitive layer and other forming layers. For the photothermographic material, for example, a surfactant, an antioxidant, a stabilizer, a plasticizer, an ultraviolet absorber, a coating aid, and the like may be used.

It is preferable that all coating solutions used for coating the photothermographic material are filtered before coating. In the filtration, the absolute or quasi-absolute filtration accuracy is 5 to 50 μm
Is preferably passed through at least once.

The application of the photothermographic material includes the application of each layer,
A successive multilayer coating method in which drying is repeated is mentioned, and roll coating methods such as reverse roll coating and gravure roll coating, blade coating, wire bar coating, and die coating are used. or,
Apply the next layer before drying the already applied layer using multiple coaters, and simultaneously dry multiple layers, slide coating, curtain coating or multiple types using an extrusion die coater with multiple slits. A simultaneous multi-layer coating method in which coating liquids are laminated and applied is also used. Among them, the latter is more preferable in that the occurrence of coating failure due to foreign matter brought in from the outside can be prevented. Furthermore,
When the simultaneous multi-layer coating method is used, the viscosity of the uppermost coating liquid at the time of coating is set to 0.1 in order to prevent mixing between layers.
It is preferable that the viscosity is 1 Pa · s or more, and the viscosity of the other layer when the coating solution is applied is 0.03 Pa · s or more. Also, when the solids dissolved in the coating liquid of each layer is laminated in a liquid state with the adjacent layer, if it is hardly soluble or insoluble in the organic solvent of the adjacent layer, it precipitates at the boundary surface and disturbs the coating film. Because it causes turbidity, the organic solvent contained most in the coating solution of each layer may be of the same type (the content of the organic solvent commonly contained in each coating solution in each solution is larger than other organic solvents) preferable.

It is preferable to dry as soon as possible after the multi-layer coating, and it is desirable to reach the drying step within 10 seconds in order to avoid interlayer mixing caused by flow, diffusion, density difference and the like. As a drying method, a hot air drying method, an infrared drying method, or the like is used, and a hot air drying method is particularly preferable. The drying temperature at that time is preferably 30 to 100 ° C.

The photothermographic material may be cut into a desired size immediately after coating and drying and then packaged, or may be wound into a roll and temporarily stored before cutting and packaging. The winding method is not particularly limited, but winding by tension control is generally used.

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)
Etc. are preferably used, but from the viewpoint that the laser power is high power and the photosensitive material can be made transparent, etc.
An infrared semiconductor laser is more preferably used.

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 closest to 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.
Say ~ 82 degrees.

When the laser beam is scanned on the photosensitive material,
The beam spot diameter on the exposed surface of the photosensitive material is preferably 2
It is at most 00 μm, more preferably at most 100 μm.
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.

The lower limit of the beam spot diameter is 10 μm.
It is. 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.

The exposure in the present invention is preferably carried out by 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.
To achieve vertical multiplication, a method of utilizing return light by multiplexing, superimposing high frequency, etc. is preferable. In addition, the vertical multi
This means that the exposure wavelength is not a single wavelength, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

The photothermographic material 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, more preferably 100 to 200 ° C.
１５０150 ° C. If the heating temperature is lower than 80 ° C., a sufficient image density cannot be obtained in a short time. On the other hand, if the heating temperature is higher than 200 ° C., the binder is melted and transferred not only to the image itself, such as transfer to a roller, but also to transportability and a developing machine. Also have an adverse effect.

By heating, a silver image is formed 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.

[0084]

EXAMPLES The present invention will be described below with reference to examples, but embodiments of the present invention are not limited to these examples.
Unless otherwise specified, “%” in Examples is “% by mass”.
Is shown. The “mol / L concentration” is represented by “M”.

<Preparation of Photosensitive Silver Halide Emulsion 1> (A1) Phenylcarbamoyl gelatin 88.3 g Compound EO (10% methanol solution) 10 ml Potassium bromide 0.32 g Finished with water to 5429 ml (B1) 0.67 M silver nitrate Aqueous solution 2635 ml (C1) 51.55 g potassium bromide 1.47 g potassium iodide Finish up to 660 ml with water (D1) 154.9 g potassium bromide 4.41 g iridium chloride (1% solution) 0.93 ml (E1) 0.4 M potassium bromide aqueous solution The following silver potential control amount (F1) 56% acetic acid aqueous solution 16.0 ml (G1) 1.72 g of anhydrous sodium carbonate Finished to 151 ml with water EO: 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) Japanese Sho 58-58288, using a mixing and stirring machine shown in Nos. 58-58289, a solution (A1), a solution (B
The 1/4 amount of 1) and the total amount of the solution (C1) were
While controlling the g at 8.09, the mixture was added by a simultaneous mixing method in 4 minutes and 45 seconds to form nuclei. After a lapse of 7 minutes, the remaining amount of the solution (B1) and the entire amount of the solution (D1) were removed at a temperature of 45
C., while controlling the pAg at 8.09,
It was added over 4 minutes and 15 seconds. During the 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 the sedimented portion, 10 L of water was added and the mixture was stirred, and the silver halide was sedimented again. The supernatant was removed except for 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.

This photosensitive silver halide emulsion 1 (hereinafter referred to as silver halide emulsion 1) has an average grain size of 0.05
Cubic silver iodobromide grains having a grain size of 8 μm, a coefficient of variation in grain size of 12%, and a [100] face ratio of 92% were obtained. The amount of iridium contained in the silver halide grains was 8.2 × 10 ^-6 mol per mol of silver, and the amount of iridium contained outside the silver halide grains was 1.6 × 10 ^-6 mol per mol of silver. The amount of gelatin contained in the emulsion was 42.5 g per mole of silver.
Met.

<Preparation of photosensitive silver halide emulsions 2 to 8>
In the step of preparing Emulsion 1, the amount of phenylcarbamoyl gelatin in solution (A1) and the amount of iridium chloride in solution (D1) were adjusted to change the amount of iridium contained in the silver halide grains and the amount of gelatin in the emulsion. Silver halide emulsions 2 to 8 were prepared in exactly the same manner as above.

Each emulsion was cubic silver iodobromide grains having the average grain size, coefficient of variation in grain size, and [100] plane ratio shown in Table 1.

<Preparation of Powder Organic Silver Salt> In 4720 ml of pure water, 130.8 g of behenic acid and 67.7 g of arachidic acid were used.
g, 43.6 g of stearic acid and 2.3 g of palmitic acid were dissolved at 80 ° C. Next, 540.2 ml of a 1.5 M 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 organic acid sodium solution is 55 ° C.
, 45.3 g of the silver halide emulsion 1 and 450 ml of pure water were added, and the mixture was stirred for 5 minutes.

Next, 702.6 ml of a 1 M silver nitrate solution was added over 2 minutes, and the mixture was stirred for 10 minutes to obtain an organic silver salt dispersion. Thereafter, the obtained organic silver salt dispersion was transferred to a water washing container, deionized water was added thereto, and the mixture was stirred and allowed to stand. Then, the organic silver salt dispersion was floated and separated to remove lower water-soluble salts. Thereafter, water washing with deionized water and drainage are repeated until the conductivity of the wastewater reaches 2 μS / cm.
The organic silver salt powder 1 was obtained by drying with a hot air circulating drier at ℃ until there was no mass loss.

The same preparation was carried out using silver halide emulsions 2 to 8, and powdered organic silver salts 2 to 8 were obtained.

<Preparation of Preliminary Dispersion> Polyvinyl butyral powder (manufactured by Monsanto: Butvar B-7)
9) 14.57 g of methyl ethyl ketone (MEK) 14
57 g, and while stirring with a dissolver DISPERMAT CA-40M, manufactured by VMA-GETZMANN, slowly add and sufficiently mix 500 g of each of the obtained powdered organic silver salts to sufficiently mix the preliminary dispersions 1 to 3. 8 was prepared.

<Preparation of photosensitive emulsion dispersion> Preliminary dispersion 1
To 8 were measured using a pump for a residence time of 10
Minutes, a media-type disperser DISPERMAT SL-C12EX filled with zirconia beads of 0.5 mm diameter (Toray Corp .: Treceram) having an inner volume of 80%.
The emulsion was supplied to a mold (manufactured by VMA-GETZMANN) and dispersed at a mill peripheral speed of 13 m / s to prepare photosensitive emulsion dispersion liquids 1 to 8.

<Preparation of Stabilizer Liquid> 1.0 g of stabilizer
1. 0.31 g of potassium acetate was added to 4.97 g of methanol.
To prepare a stabilizer solution.

<Preparation of infrared sensitizing dye liquid> 19.2 mg of infrared sensitizing dye-1, 1.488 g of 2-chloro-benzoic acid, 2.779 g of stabilizer-2 and 365 mg of 5-methyl -2-mercaptobenzimidazole 31.3m
1 MEK in a dark place to prepare an infrared sensitizing dye solution.

<Preparation of Additive Solution a> 27.98 g of Reducing Agent-1, 1.54 g of 4-methylphthalic acid, and 0.48 g of Infrared Dye-1 were dissolved in 110 g of MEK to prepare Additive Solution a.

<Preparation of Additive Solution b> 3.56 g of antifoggant-2, 3.43 g of phthalazine were added to 40.9 g of MEK.
To give an additive solution b.

<Preparation of Coating Solution for Photosensitive Layer> While stirring 50 g of each photosensitive emulsion dispersion and 15.11 g of MEK at 21 ° C.
, Fog inhibitor-1 (10% methanol solution)
390 μl was added and stirred for 1 hour. Further, 494 μl of calcium bromide (10% methanol solution) was added to
Stirred for 0 minutes. Subsequently, 167 mg of a stabilizer solution was added and stirred for 10 minutes, and then 2.622 g of an infrared sensitizing dye solution was added and stirred for 1 hour. Thereafter, 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 (supra: Butvar B-79)
After adding 13.31 g and stirring for 30 minutes, 1.084 g of tetrachlorophthalic acid (9.4% MEK solution) was added and stirred for 15 minutes. 11. While continuing stirring,
43 g of additive solution a, 1.6 ml of crosslinking agent solution (manufactured by Mobay: Desmodur N3300, 10% MEK solution of aliphatic isocyanate), 4.37 g of additive solution b
Were sequentially added and stirred to obtain a photosensitive layer coating solution.

<Preparation of Matting Agent Dispersion> Cellulose acetate butyrate (Eastman Chemical)
Co., Ltd .: 7.5 g of CAB171-15) was added to MEK42.
5 g, and calcium carbonate (Specia)
manufactured by lite Minerals: Super-Pfl
ex200), and dispersed by a dissolver-type homogenizer at 8000 rpm for 30 minutes to prepare a matting agent dispersion.

<Preparation of Surface Protective Layer Coating Solution> MEK865
While stirring g, 96 g of cellulose acetate butyrate (mentioned above: CAB171-15) and polymethyl methacrylic acid (Rohm & Haas: Paraloid A-21)
4.5 g, vinyl sulfone compound (HD-1) 1.5
g, benzotriazole (1.0 g) and a fluorine-based activator (Asahi Glass Co., Ltd .; Surflon KH40) (1.0 g) were added and dissolved. Next, 30 g of a matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

The structures of the additives used in the respective additive solutions or the respective coating solutions are shown below.

[0104]

Embedded image

[0105]

Embedded image

<Coating on the photosensitive layer side> The viscosity of the coating solution for the photosensitive layer and the coating solution for the surface protective layer were adjusted to 0.228 Pa · s and 0.184 Pa ·
After filtration through a filter having a quasi-absolute filtration accuracy of 20 μm, the mixture was discharged from a slit of an extrusion die coater, laminated, and simultaneously coated on a support.
After 8 seconds, drying was performed for 5 minutes using hot air having a drying temperature of 75 ° C. and a dew point of 10 ° C., and then the ambient temperature and humidity were 23 ° C. and 50% RH.
(Relative humidity) and rolled up at a tension of 196 N / m (20 kg / m) to produce photothermographic materials 1 to 8.

The photosensitive layer of the obtained photosensitive material had a coated silver amount of 1.9 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm.

<Exposure and development processing> From the emulsion side of the photosensitive material prepared as described above, a wavelength of 800
Exposure by laser scanning was given by an exposure machine using a semiconductor laser having a vertical multi-mode of ８820 nm as a light emitting source. At this time, an image was formed by setting the angle between the exposure surface of the photosensitive material and the exposure laser beam to 75 degrees (the unevenness was smaller and the sharpness and the like were unexpectedly better than when the angle was set to 90 degrees). Image was obtained).

Thereafter, heat development was performed at 110 ° C. for 15 seconds using an automatic developing machine having a heat drum so that the protective layer of the photosensitive material was in contact with the drum surface. At that time, exposure and development were performed in a room conditioned at 23 ° C. and 50% RH.

<< Evaluation of Sensitometry >> The obtained images were evaluated using a densitometer. Sensitivity (1.
Evaluation was made based on the reciprocal of the ratio of the amount of exposure that gives a high density (0) and fog.

<< Evaluation of Silver Tone >> For evaluation of silver tone,
A sample exposed and developed so that the density after development was 1.1 ± 0.05 was produced. This sample was placed on a light source at a color temperature of 7700 Kelvin and an illuminance of 11600 lux for 10 hours.
Irradiation was carried out for 0 hour and 1000 hours, and the evaluation was performed in five steps based on the following criteria. In terms of quality assurance, there is no problem with a rank of 4 or more.

5: Pure black tone and no yellow tinge 4: Not pure black but almost no yellow tinge 3: Partially slightly yellow tinge 2: Slight yellow tinge on entire surface 1: At first glance, a yellow color is felt. << Evaluation of image preservation >> Two samples treated in the same manner as in the sensitometry evaluation were stored at 25 ° C. and 55% RH for 7 days, and another sample was stored. Was exposed to natural light at 25 ° C. and 55% RH for 7 days, and then the concentration of the fogged portion was measured.

Increase in fog = fog when exposed to natural light-fog when preserved from light, the image storability was evaluated.

Table 1 also shows the results.

[0115]

[Table 1]

The light-sensitive material of the present invention has high sensitivity, low fog, a pure silver tone, and excellent image storability.

Example 2 The procedure of Example 1 was repeated, except that the iridium chloride in the solution (D1) was changed to rhodium chloride and ruthenium chloride in the preparation step of the photosensitive silver halide emulsion of Example 1. A photosensitive material was prepared and evaluated in the same manner. Table 2 shows the results.

[0118]

[Table 2]

The light-sensitive material of the present invention is excellent in any of the evaluations. Example 3 A photosensitive material was prepared in exactly the same manner as in Example 1 except that the pH was adjusted to the value shown in Table 3 after the nucleation was completed in the preparation step of the photosensitive silver halide in Example 1, and the same evaluation was performed. went. An aqueous potassium hydroxide solution or an acetic acid solution was used for pH adjustment during the preparation of silver halide. Table 3 shows the results.

[0120]

[Table 3]

The superiority of the photosensitive material according to claim 4 of the present invention is apparent. Example 4 A photosensitive material was prepared in exactly the same manner as in Example 1 except that the amount of the photosensitive silver halide shown in Table 4 was changed in the preparation process of the powdered organic silver salt of Example 1. Was evaluated. Table 4 shows the results.

[0122]

[Table 4]

The light-sensitive material satisfying claim 3 of the present invention showed good results particularly in image storability.

[0124]

According to the present invention, a photothermographic material having high sensitivity, low fog, excellent silver tone (pure black tone), and excellent image storability can be obtained.

Claims (7)

[Claims] 1. A non-photosensitive organic silver salt, a photosensitive silver halide, a reducing agent capable of reducing silver ions of the organic silver salt to silver when activated by heat, a binder, and a crosslinking agent for the binder. A photothermographic material comprising the photothermographic material, wherein the photosensitive silver halide satisfies the following conditions (1) to (3). (1) The photosensitive silver halide contains at least one transition metal selected from elements of Groups 6 to 11 of the periodic table. (2) The photosensitive colloid contained in the photosensitive silver halide is silver 1 (3) The hydrophilic colloid is 6 × 10 ⁶ g or more per 1 mol of the transition metal. 2. The photothermographic material according to claim 1, wherein the transition metal is a metal selected from iron, cobalt, ruthenium, rhodium, rhenium, osmium and iridium. 3. The photothermographic material according to claim 1, wherein the silver ratio of the photosensitive silver halide to the non-photosensitive organic silver salt is 3 to 7%. 4. The process for forming silver halide has a pH of 3
4. The method according to claim 1, wherein the step is performed in a range of from 6 to 6.
The photothermographic material according to the above. 5. A laser beam on the photothermographic material according to claim 1, wherein the angle between the exposed surface of the photothermographic material and the scanning laser beam is not substantially perpendicular. An image recording method, wherein exposure is performed by a scanning exposure machine. 6. The photothermographic material according to claim 1, wherein a scanning laser beam for recording an image is exposed by a laser beam scanning exposure machine having a vertical multi-scan. Image recording method. 7. An image forming method, wherein the photothermographic material according to claim 1 is developed by heating at 80 to 200 ° C.