JP2005172892A - Silver salt photothermographic dry imaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material having good suitability to coating and excellent in in-plane uniformity of a processed image. <P>SOLUTION: The silver salt photothermographic dry imaging material has at least one imaging layer and at least one protective layer in this order on at least one surface of a support, wherein at least one layer selected from the imaging layer and the protective layer contains a copolymer obtained by suspension-polymerizing a monomer composition including a fluorine-containing acrylate or a fluorine-containing methacrylate in an aqueous medium. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a silver salt photothermographic dry imaging material.

  Silver halide light-sensitive materials that have been widely used in the past have been used in the field of image formation as a broader and higher-quality material due to their excellent photographic characteristics, but development, fixing, The process of washing with water and drying is necessary, and the processing steps are wet, so that the work is complicated. For this reason, a silver salt photothermographic dry imaging material in which the development process is performed by heat treatment has been developed and put into practical use, and has recently been rapidly spread mainly in the medical industry.

  As such a technique, for example, a silver salt photothermographic dry imaging material having an organic silver salt, photosensitive silver halide grains and a reducing agent on a support (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1) is known. It has been. Since this silver salt photothermographic dry imaging material (a silver halide photographic light-sensitive material for heat development) does not use any solution processing chemicals, a simpler system can be provided to the user.

In the production of silver salt photothermographic dry imaging materials, a binder of 5 g / m ² or more is usually required in order to suppress damage to silver halide particles and organic silver salt particles and increase in fog during heat development. In order to reduce the drying load, it is usually necessary to apply with a coating solution viscosity of 100 mPa · s or more.

  In the simultaneous multi-layer coating method in which a plurality of coating liquids are stacked and applied, a failure in which the image density is partially white tends to occur due to unevenness caused by foreign matters such as dust on the support and the support transport roll. Further, a surface failure (wind unevenness) due to wind during drying may occur. Further, if a high-viscosity coating solution is simply used so that wind unevenness does not occur, the coating property is remarkably deteriorated and a streak failure occurs. In order to make these failures compatible, it is usually handled by lowering the drying air speed, but the drying ability is impaired and the high-speed coating property is lost.

  Although there is disclosure as a technique for improving uniformity on the surface of silver salt photothermographic dry imaging material and high-speed coating property during production (for example, see Patent Document 3), sufficient high-speed coating property is obtained. The current situation is that it is not possible.

Also, silver salt photothermographic dry imaging materials often result in non-uniform images and a solution is sought.
US Pat. No. 3,152,904 US Pat. No. 3,487,075 JP 11-52509 A (Claims) D. Morgan: Dry Silver Photographic Materials (Handbook of Imaging Materials, Marcel Dekker, Inc.) p. 48, 1991

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silver salt photothermographic dry imaging material having good coating properties and excellent in-plane uniformity of processed images.

The above object of the present invention can be achieved by the following configuration.
(Claim 1)
A silver salt photothermographic dry imaging material having at least one image forming layer and a protective layer in this order on at least one surface of a support, respectively, wherein at least one layer of the image forming layer contains a fluorine-containing acrylate or An image forming layer coating solution containing a copolymer obtained by suspension polymerization of a monomer composition containing a fluorine-containing methacrylate in an aqueous medium, and the image forming layer satisfying the following viscosity conditions is applied and dried. A silver salt photothermographic dry imaging material obtained by
(Viscosity condition)
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, when applying vibration with strain of 0.4 and frequency of 2 Hz for 5 minutes, the viscosity immediately after the start of vibration is η _A , and vibration is started. When the viscosity after 5 minutes is η _B , 2.00> η _B / η _A > 1.20.
(Claim 2)
A silver salt photothermographic dry imaging material having at least one image forming layer and a protective layer in this order on at least one surface of a support, the fluorine-containing acrylate or fluorine A monomer composition containing a methacrylate containing a copolymer obtained by suspension polymerization in an aqueous medium, and the protective layer obtained by coating and drying a protective layer coating solution that satisfies the following viscosity conditions: A silver salt photothermographic dry imaging material characterized by the above.
(Viscosity condition)
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, when applying vibration with a strain of 0.4 and a frequency of 2 Hz for 5 minutes, the viscosity immediately after the start of vibration is η _C , and vibration is started. When the viscosity after 5 minutes is η _D , 2.00> η _D / η _C > 1.09.

  According to the present invention, a silver salt photothermographic dry imaging material having good coatability and excellent in-plane uniformity of a processed image was obtained.

  The present invention will be described in more detail. In this specification, the image forming layer is also called a photosensitive layer, and the protective layer is also called a non-photosensitive layer.

  The copolymer according to the present invention will be described. The copolymer according to the present invention can be obtained by polymerizing at least a monomer unit of fluorine-containing acrylate or fluorine-containing methacrylate, and this can be represented by the following general formula (1).

General formula (1)
CH ₂ = C (R ² ) COOL (Rf) _X
In the general formula (1), R ² is a methyl group, a hydrogen atom, or a fluorine atom, L is a simple bond, a linear or branched alkyl group, or a hydrocarbyl group, and O, S, N, P Such a substituted or unsubstituted heteroatom may be present, and Rf is a chain of fully fluorinated carbon atoms which are a straight chain, a branched chain or a cyclic chain.

  The structural unit represented by the general formula (1) can be obtained by polymerizing a monomer such as the corresponding fluoroalkyl acrylate, fluoroalkyl methacrylate, fluoroalkyl α-fluoro acrylate. In particular, fluoroalkyl acrylate and fluoroalkyl methacrylate are preferable, and commercially available products are sold by Daikin Chemicals Sales Co., Ltd. under the following trade names and are available. For example, M-1110 (2,2,2, -trifluoroethyl methacrylate), M-1210 (2,2,3,3,3-pentafluoropropyl methacrylate), M-1420 (2- (perfluorobutyl) ) Ethyl methacrylate), M-1433 (3- (perfluorobutyl) -2-hydroxypropyl methacrylate), M-5210 (1H, 1H, 3H-tetrafluoropropyl methacrylate), M-5410 (1H, 1H) , 5H-octafluoropentyl methacrylate), M-7210 (1H-1- (trifluoromethyl) trifluoroethyl methacrylate), M-7310 (1H, 1H, 3H-hexafluorobutyl methacrylate), R-1110 (2, 2,2, -trifluoroethyl acrylate), R-1210 (2 2,3,3,3-pentafluoropropyl acrylate), R-1420 (2- (perfluorobutyl) ethyl acrylate), R-1433 (3- (perfluorobutyl) -2-hydroxypropyl acrylate), R- 5210 (1H, 1H, 3H-tetrafluoropropyl acrylate), R-5410 (1H, 1H, 5H-octafluoropentyl acrylate), R-7210 (1H-1- (trifluoromethyl) trifluoroethyl acrylate), R -7310 (1H, 1H, 3H-hexafluorobutyl acrylate) is listed in the catalog.

  Next, the structural unit copolymerizable with the monomer unit of fluorine-containing acrylate or fluorine-containing methacrylate will be described. This structural unit can be represented by the following general formula (2).

General formula (2)
CH ₂ = C (R ³ ) COOY
In the general formula (2), R ³ represents a hydrogen atom or a methyl group, Y represents an alkyl group, an alicyclic group, or an aromatic ring group, and it is important that the hydratable group is not contained.

  Specifically, alkyl acrylate (for example, methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, iso-nonyl acrylate, n-dodecyl acrylate, stearyl acrylate, etc.), benzyl acrylate, Cyclohexyl acrylate, glycidyl acrylate, alkyl methacrylate (eg, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, iso-nonyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, stearyl methacrylate, etc.), benzyl methacrylate, Cyclohexyl Methacrylates, can be exemplified glycidyl methacrylate, but are not these limitations.

  The copolymer according to the present invention can be polymerized by a known suspension polymerization method in which a vinyl unsaturated group is polymerized from a monomer.

  Polymerization initiators that can be used for the polymerization of the copolymer according to the present invention include, for example, coordination anion polymerization using a transition metal catalyst such as a radical initiator, an anionic initiator, a cationic initiator, a Ziegler-Natta catalyst, etc. An initiator polymerization method suitable for the monomer can be selected, and industrially, it is preferable to use a radical polymerization method among them.

  The polymerization initiator used in the suspension polymerization method in the present invention is preferably an oil-soluble initiator that is soluble in a monomer, such as oil-soluble peroxides and azobis compounds that are generally used. Can be used. Examples include 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (isobutyronitrile), lauryl peroxide, benzoyl peroxide, etc., but no gas is generated during polymerization. Lauryl peroxide and benzoyl peroxide are preferred. The amount of these oil-soluble initiators used is 0.1 to 10 mol% of the monomer used.

Examples of the hardly water-soluble inorganic compound used as the dispersant for the copolymer according to the present invention include, for example, barium sulfate, magnesium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, calcium carbonate and the like, poorly water-soluble salts, orthophosphate , Pyrophosphates, polyphosphates, poorly water-soluble phosphates, silica, alumina and the like. Preferred are dibasic phosphate (M ₂ HPO ₄ ), tertiary phosphate (M ₃ PO ₄ ), orthophosphate pyrophosphate (M ₄ P ₂ O ₇ ), pyrophosphate acid salt (M ₂ H _2). P ₂ O ₇ ) and tripolyphosphate (M ₅ P ₃ O ₁₀ ), where M is a metal salt such as calcium, magnesium, barium, iron, cadmium, or strontium. Further, for example, addition products of tribasic sodium phosphate and calcium chloride, such as Ca ₃ (PO ₄ ) ₂ .Ca (OH) ₂ , hydroxyapatite [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ], and the like are also used. Can do. Particularly preferred is tricalcium phosphate [Ca ₃ (PO ₄ ) ₂ ].

  Surfactants used as dispersion aids include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl (phenyl) ether sulfate, sodium dialkylsulfosuccinate, and polyoxyethylene alkyl (phenyl) ether. Nonionic surfactant, sodium salt of (meth) acrylic acid polyoxyethylene sulfate, sodium salt of alkylallylsulfosuccinate, anionic polymerizable surfactant such as glyceryl allyl nonylphenyl polyoxyethylene sulfate ammonium ether, polyoxy Nonionic polymerizable surfactants such as ethylene alkylbenzene (meth) acrylate and glyceryl allyl nonylphenyl polyethylene glycol ether That. These are preferably used in the range of 0.001 to 10% by mass in the aqueous suspension.

  Examples of the water-soluble polymer substance used as a dispersion aid include gelatin, starch, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose and the like. These are preferably used in the range of 0.1 to 30% by mass in the aqueous suspension.

  Examples of the organic polymerization inhibitor used in the present invention include N, N-diethylhydroxylamine, N-nitrosodiphenylamine, 2,4-dinitrophenylhydrazine, p-phenylenediamine, phenothiazine, alloocimene, triethylphosphite, 4-nitrosophenol. 2-nitrophenol, p-aminophenol, 4-hydroxy TEMPO, hydroquinone, hydroquinone monomethyl ether, p-methoxyhydroquinone, t-butyl-p-hydroquinone, 2,5-t-butylhydroquinone, 2,5-di- Examples thereof include t-butyl-p-hydroquinone, 1,4-naphthalenediol, 4-t-butylcatechol, butylhydroxytoluene, copper sulfate, copper nitrate, cresol, and phenol. Of these, 4-t-butylcatechol and 2,5-t-butylhydroquinone are particularly preferred. These are preferably used in the range of 1 to 1000 ppm in the monomer. Moreover, a chain transfer agent can also be added in a monomer as needed.

  In the present invention, a water-soluble polymerization initiator may be added to the aqueous medium after the polymer particles are formed. Examples of the water-soluble polymerization initiator used in the present invention include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2 '-Azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, etc. An azo-type initiator etc. can be mentioned. These can be used alone or in combination of two or more, and persulfate is particularly preferable. The addition amount of the water-soluble polymerization initiator is preferably in the range of 0.01 to 1.0% by mass with respect to 100% by mass of the granular polymer.

  As other polymerization conditions, the reaction temperature is preferably 50 to 90 ° C, more preferably 55 to 85 ° C.

  The number average molecular weight (Mn) in the present invention indicates that measured by gel permeation chromatography (GPC). The synthesis example of the copolymer of the present invention is shown below.

<< Synthesis of copolymer polymer >>
[Synthesis of Copolymer PF-1 of the Present Invention]
(Monomer composition)
Polymerizable monomer: M-1210 40 parts Polymerizable monomer: M-5210 40 parts Polymerizable monomer: MMA 20 parts M-1210: 2,2,3,3,3-pentafluoropropyl methacrylate ( Daikin Industries, Ltd.)
M-5210: 2,2,3,3-tetrafluoropropyl methacrylate (manufactured by Daikin Industries)
MMA: Methyl methacrylate After mixing and homogenizing the above polymerizable monomers, 4 parts of lauryl peroxide (hereinafter abbreviated as LPO) as a polymerization initiator was added thereto.

(Aqueous medium)
<Liquid A>
Trisodium phosphate dodecahydrate (Na ₃ PO ₄ .12H ₂ O) 3 parts Sodium dodecylbenzenesulfonate (C ₁₂ H ₂₅ C ₆ H ₄ SO ₃ Na) 0.01 part Water (H ₂ O) 20 parts <Liquid B>
Calcium chloride (CaCl ₂ ) 2 parts Water (H ₂ O) 180 parts The above solutions A and B were mixed to prepare an aqueous medium containing a hardly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ]. This poorly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] is produced by a reaction represented by the following formula.

2Na ₃ PO ₄ + 3CaCl ₂ → Ca ₃ (PO ₄ ) ₂ + 6NaCl
(Polymerization reaction)
The monomer composition and the aqueous medium are added to a 0.5 liter round bottom flask equipped with a thermometer, a reflux condenser, a nitrogen inlet, and a stirring blade, and stirred for 10 minutes at 300 rpm while blowing nitrogen gas. did. After confirming that the monomer droplets were stable, the temperature was raised to 70 ° C., and polymerization was carried out at this temperature for 6 hours to obtain a copolymer dispersion.

(Post-processing)
Next, the mixture is cooled to room temperature, 4 g of concentrated hydrochloric acid is added to the copolymer dispersion in an aqueous medium, and the hardly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] is completely dissolved and removed. It washed with water until the degree became 1.0 micro S / cm or less, filtered and dried, and obtained PF-1 which is a copolymer of the present invention. The number average molecular weight is 120,000.

[Synthesis of Copolymer PF-2 of the Present Invention]
(Monomer composition)
Polymerizable monomer: M-1210 10 parts Polymerizable monomer: M-5210 60 parts Polymerizable monomer: MMA 30 parts Polymerization initiator: LPO 4 parts (aqueous medium)
<Liquid A>
Trisodium phosphate dodecahydrate (Na ₃ PO ₄ .12H ₂ O) 3 parts Water (H ₂ O) 20 parts <Liquid B>
Calcium chloride (CaCl ₂ ) 2 parts Water (H ₂ O) 180 parts The above solutions A and B were mixed to prepare an aqueous medium containing a hardly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ].

(Polymerization reaction)
The monomer composition and the aqueous medium were added to a 0.5 liter round bottom flask equipped with a thermometer, a reflux condenser, a nitrogen inlet, and a stirring blade, and stirred at 300 rpm for 10 minutes while blowing nitrogen gas. After confirming that the monomer droplets were stable, the temperature was raised to 70 ° C., and polymerization was carried out at this temperature for 6 hours to obtain a copolymer dispersion.

(Post-processing)
Next, the mixture is cooled to room temperature, 4 g of concentrated hydrochloric acid is added to the copolymer dispersion in the aqueous medium, and the hardly water-soluble inorganic compound [Ca ₃ (PO ₄ ) ₂ ] is completely dissolved and removed. It washed with water until the degree became 1.0 micro S / cm or less, filtered and dried, and obtained PF-2 which is a copolymer of the present invention. The number average molecular weight is 140000.

[Synthesis of the copolymer PF-3 of the present invention]
(Monomer composition)
Polymerizable monomer: R-1420 50 parts Polymerizable monomer: CHMA 30 parts Polymerizable monomer: GMA 20 parts Polymerization initiator: LPO 4 parts R-1420: (2- (perfluorobutyl) ethyl acrylate ) (Daikin Industries)
CHMA: cyclohexyl methacrylate GMA: glycidyl methacrylate (aqueous medium)
Hydroxyapatite [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ] 3 parts Water (H ₂ O) 200 parts The above is mixed and contains a poorly water-soluble inorganic compound [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ] An aqueous medium was prepared.

(Polymerization reaction)
The monomer composition and the aqueous medium were added to a 0.5 liter round bottom flask equipped with a thermometer, a reflux condenser, a nitrogen inlet, and a stirring blade, and stirred at 300 rpm for 10 minutes while blowing nitrogen gas. After confirming that the monomer droplets were stable, the temperature was raised to 70 ° C., and polymerization was carried out at this temperature for 6 hours to obtain a copolymer dispersion.

(Post-processing)
Next, the mixture is cooled to room temperature, 4 g of concentrated hydrochloric acid is added to the copolymer dispersion in the aqueous medium, and the hardly water-soluble inorganic compound [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ] is completely dissolved and removed. The washed water was washed until the conductivity of the washing water became 1.0 μS / cm or less, filtered and dried to obtain PF-3 which is a copolymer of the present invention. The number average molecular weight is 130000.

  When the copolymer of the present invention is added, the reason for achieving the object of the present invention is presumed to be a remarkable effect because the effect of suppressing unevenness of the coating film surface during coating and drying is large.

As content of the copolymer of this invention, 0.4-2500 g / m < ² > is preferable and 2.0-1200 g / m < ² > is more preferable. In the case of having two or more image forming layers, each image forming layer is preferably in this range. Moreover, as content of the copolymer of this invention, 0.4-2500 g / m < ² > is preferable about a protective layer, and 2.0-1200 mg / m < ² > is more preferable.

  Any apparatus may be used for the viscosity measurement of the present invention, but Rheo Stress RS1 manufactured by Harke is preferably used.

In the present invention, the viscosity of at least one coating solution of the image forming layer is immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, giving a vibration of 0.4 minutes and a frequency of 2 Hz. When the viscosity immediately after the start of vibration is η _A and the viscosity 5 minutes after the start of vibration is η _B , 1.09> η _B / η _A > 1.02.

The coating solution viscosity of at least one layer of the protective layer in the present invention was immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, giving a vibration of 0.4 minutes and a frequency of 2 Hz for 5 minutes. When the viscosity immediately after the start of vibration is η _C and the viscosity 5 minutes after the start of vibration is η _D , 2.00> η _D / η _C > 1.09.

If η _B / η _A and η _D / η _C are too high, they are easily affected by drying conditions, and applicability may deteriorate. On the other hand, if η _B / η _A and η _D / η _C are too low, they are easily affected by drying air during drying, and coating unevenness may occur due to undulation of the coating surface.

  As a method for controlling the viscosity of the coating solution of the present invention, a method of changing the concentration of the coating solution by controlling the amount of the solvent or the amount of the binder containing the polysiloxane-polyoxyalkylene block copolymer of the present invention, various rheology control agents The method etc. which add can be used.

In Patent Document 3 (Japanese Patent Laid-Open No. 11-52509), the viscosity at shear rates of 0.1 (1 / s = second ⁻¹ ) and 1000 (1 / s) is specified. Immediately after applying shearing at a shear rate of 1000 (1 / s), the viscosity is specified when vibration with a strain of 0.4 and a frequency of 2 Hz is applied. The point that the specified viscosity includes a value in a state where the steady flow is not reached is considered to be related to a factor leading to the effect of the present invention.

  The shear rate in the present invention is based on a definition that is normally used. When a fluid is poured between flat plates arranged in parallel at an interval h, one is fixed and the other is translated at a speed V. The velocity gradient (V / h) was measured.

  On the other hand, the strain γ in the present invention is expressed by the amount of deformation per unit length, and is a strain when a disc plate having a radius R is coaxially installed at intervals H and is vibrated at a rotation angle θ. Is obtained by the following equation.

Strain = (radius R of disk plate) × (rotation angle θ) / (gap H between upper and lower plates)
According to the viscosity measurement conditions in the present invention (viscosity when applying shearing at a shear rate of 1000 (1 / s) and then applying a strain of 0.4 and a frequency of 2 Hz), an appropriate viscosity range of the coating liquid is obtained. Whether it can be specified is not necessarily clear.

  Considering the process of applying and drying a coating solution such as an image forming layer solution or a protective layer solution, the coating solution is first coated on the support. At this time, a considerable shear force is applied to the coating solution. Subsequently, in the drying step, the liquid coated on the support is dried while receiving the vibration of the transport roll.

  Of course, in the drying process, the characteristics may change over time, and local and local areas may vary. Furthermore, when measuring the shear rate and viscosity, it is difficult to measure too large or small values, and even if performed, there are often problems with accuracy. However, if it is defined as in the present invention, the effect of the present invention is remarkably obtained because the characteristics of the coating solution at the time of coating, or at least the characteristic values correlated therewith are measured and defined. . Note that the specified values such as shear rate and viscosity in the present invention are within a range that can be measured with great ease with currently used measuring instruments.

  The simultaneous multilayer coating method in the present invention may be any method. Specifically, a dip coating method, a roller coating method, a curtain coating method, an extrusion coating method, a slide hopper method, and the like can be used. In the section of “Coating Processes” (RD 176, pages 27 to 28). It is described in detail.

  Next, the silver salt photothermographic dry imaging material according to the present invention will be described.

[Amount of coated silver]
In the present invention, the amount of silver applied is 1 × 10 ^{4 to} 5 × 10 ⁵ g / m ³ per unit volume in the photosensitive layer after coating, drying and before exposure and heat development. Silver sources corresponding to the amount of silver added are photosensitive silver halide, silver halide grains prepared by converting a halogen-containing compound to an organic silver salt and converting an aliphatic carboxylic acid silver salt, and an aliphatic carboxylic acid. The total of all silver salt resources such as silver salt.

In the present invention, the coating density of silver halide grains having an average particle diameter (equivalent sphere equivalent particle diameter) of 0.01 μm or more is preferably 1 × 10 ¹⁴ / m ² or more and 1 × 10 ¹⁸ / m ² or less. Furthermore, it is preferably 1 × 10 ¹⁵ / m ² or more and 1 × 10 ¹⁷ / m ² or less.

Furthermore, the coating density of the aliphatic carboxylic acid silver salt of the present invention is 10 ⁻¹⁷ g or more, 10 ⁻¹⁴ g or less, more preferably 10 μg per silver halide grain of 0.01 μm or more (equivalent particle diameter equivalent to sphere). ^-16 g or more and 10 ^-15 g or less is preferable.

  When coated under the conditions within the above range, it is preferable from the viewpoint of the optical maximum density of the silver image per fixed coated silver amount, that is, the silver coating amount (covering power) and the color tone of the silver image. Results are obtained.

[Silver ion reducing agent]
Although there is no limitation in particular as a silver ion reducing agent used for this invention, The bisphenol derivative represented with the following general formula (A) or general formula (S) is used preferably. In particular, by using a compound in which at least one silver ion reducing agent is a bisphenol derivative alone or in combination with a reducing agent having another different chemical structure, performance deterioration due to fog generation during storage of a silver salt photothermographic imaging material In addition, color tone deterioration and the like in storage of a silver image after heat development are unexpectedly suppressed.

  In general formula (A), X represents a chalcogen atom or CHR, and R represents a hydrogen atom, a halogen atom, an aliphatic group having 7 or less carbon atoms, or a cyclic group having 6 or less ring members. R ′ and R ″ each represent a hydrogen atom, a halogen atom or a substituent.

In the general formula (S), Z represents an atomic group necessary to form a 3- to 10-membered ring together with a carbon atom, and R _x represents a hydrogen atom or an alkyl group. R ₀ ′, R ₀ ″ and Q ₀ each represents a substitutable group on the benzene ring, and n and m represent an integer of 0 to 2. A plurality of R ₀ ′, R ₀ ″ and Q ₀ are the same or different. May be.

  In the general formula (A), the chalcogen atom represented by X is sulfur, selenium or tellurium, preferably a sulfur atom.

  In the general formula (A), examples of the halogen atom represented by R in CHR include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the aliphatic group having 7 or less carbon atoms include methyl group, ethyl group, propyl group, butyl group, hexyl group, heptyl group, vinyl group, allyl group, butenyl group, hexadienyl group, and ethenyl-2-propenyl group. 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group and the like. The cyclic group having 6 or less members includes an alicyclic group and a heterocyclic group, and the carbocyclic group includes a cyclobutene group, a cyclopentyl group, a cyclopentenyl group, a cyclohexyl group, a cyclohexenyl group, and a cyclohexadienyl group. , A 4- to 6-membered ring such as a phenyl group is preferable, and examples of the heterocyclic group include a pyrazole ring, a pyrrole ring, a pyrrolidine ring, a pyrimidine ring, a pyrazine ring, a pyridine ring, a triazine ring, a thiazole ring, a furan ring, and a pyran ring. A 5- or 6-membered ring is preferable, and a hydrogen atom or a group having a cyclic structure such as a cycloalkyl group, a cycloalkenyl group, or a phenyl group is particularly preferable.

  These groups may further have a substituent. Examples of the substituent include a halogen atom (for example, fluorine atom, chlorine atom, bromine atom), cycloalkyl group (for example, cyclohexyl group, cycloheptyl group, etc.). A cycloalkenyl group (eg, 1-cycloalkenyl group, 2-cycloalkenyl group, etc.), an alkoxy group (eg, methoxy group, ethoxy group, propoxy group, etc.), an alkylcarbonyloxy group (eg, acetyloxy group, etc.), An alkylthio group (eg, methylthio group, trifluoromethylthio group, etc.), carboxyl group, alkylcarbonylamino group (eg, acetylamino group, etc.), ureido group (eg, methylaminocarbonylamino group, etc.), alkylsulfonylamino group (eg, , Methanesulfonylamino group, etc.), alkylsulfonyl (For example, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), carbamoyl group (for example, carbamoyl group, N, N-dimethylcarbamoyl group, N-morpholinocarbonyl group, etc.), sulfamoyl group (sulfamoyl group, N, N-dimethylsulfur group, etc.) Famoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkylsulfonamide group (for example, methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group (for example, Amino group, N, N-dimethylamino group, N, N-diethylamino group, etc.), sulfo group, phosphono group, sulfite group, sulfino group, alkylsulfonylaminocarbonyl group (for example, methanesulfonylaminocarbonyl group, ethanesulfonylamino group) Carbonyl group etc.), alkylcarbonylaminosulfonyl group (eg acetamidosulfonyl group, methoxyacetamidosulfonyl group etc.), alkynylaminocarbonyl group (eg acetamidocarbonyl group, methoxyacetamidocarbonyl group etc.), alkylsulfinylaminocarbonyl group (eg Methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group and the like). Moreover, when there are two or more substituents, they may be the same or different.

  R ′ and R ″ each represent a hydrogen atom, a halogen atom or a substituent. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom. Examples of the substituent include an alkyl group and an aryl group. Group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, amino group, acyl group, acyloxy group, acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, sulfonyl group, alkylsulfonyl group, sulfinyl group , A cyano group, a heterocyclic group, etc. A plurality of R ′ and R ″ may be the same or different.

  R ′ preferably has 2 or more carbon atoms. R ″ preferably has 1 to 5 carbon atoms, more preferably 1 carbon atom. These groups may further have a substituent, and examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom). , Bromine atom, etc.), alkyl group (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, etc.), cycloalkyl group ( For example, cyclohexyl group, cycloheptyl group, etc.), alkenyl group (for example, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group) Etc.), cycloalkenyl groups (eg 1-cycloalkenyl group, 2-cycloalkenyl group etc.), alkynyl groups (eg ethynyl group, 1-propynyl group etc.) , Alkoxy groups (eg methoxy group, ethoxy group, propoxy group etc.), alkylcarbonyloxy groups (eg acetyloxy group etc.), alkylthio groups (eg methylthio group, trifluoromethylthio group etc.), carboxyl groups, alkylcarbonyl Amino group (eg, acetylamino group), ureido group (eg, methylaminocarbonylamino group), alkylsulfonylamino group (eg, methanesulfonylamino group), alkylsulfonyl group (eg, methanesulfonyl group, trifluoromethane) Sulfonyl groups, etc.), carbamoyl groups (eg, carbamoyl groups, N, N-dimethylcarbamoyl groups, N-morpholinocarbonyl groups, etc.), sulfamoyl groups (sulfamoyl groups, N, N-dimethylsulfamoyl groups, morpholinosulphates) Amoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkylsulfonamide group (eg methanesulfonamide group, butanesulfonamide group etc.), alkylamino group (eg amino group, N, N- Dimethylamino group, N, N-diethylamino group, etc.), sulfo group, phosphono group, sulfite group, sulfino group, alkylsulfonylaminocarbonyl group (for example, methanesulfonylaminocarbonyl group, ethanesulfonylaminocarbonyl group, etc.), alkylcarbonyl An aminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.), an alkynylaminocarbonyl group (eg, acetamidocarbonyl group, methoxyacetamidocarbonyl group, etc.), alkylsulfinylaminocarbonyl, etc. Examples include a sulfonyl group (for example, methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group, etc.) and the like.

  Specific examples of the compound represented by the general formula (A) are shown below.

  In the general formula (S), Z represents a group of atoms necessary to form a 3- to 10-membered non-aromatic ring together with a carbon atom. As the ring, specifically, the 3-membered ring includes cyclopropyl, aziridyl, Oxiranyl, 4-membered ring is cyclobutyl, cyclobutenyl, oxetanyl, azetidinyl, 5-membered ring is cyclopentyl, cyclopentenyl, cyclopentadienyl, tetrahydrofuranyl, pyrrolidinyl, tetrahydrothienyl, 6-membered ring is cyclohexyl, cyclohexenyl, cyclohexadienyl Enyl, tetrahydropyranyl, pyranyl, piperidinyl, dioxanyl, tetrahydrothiopyranyl, norcaranyl, norpinanyl, norbornyl, 7-membered ring is cycloheptyl, cycloheptynyl, cycloheptadienyl, 8-membered ring is cyclooctyl Nyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, 9-membered ring is cyclononanyl, cyclononenyl, cyclononadienyl, cyclononatrienyl, and 10-membered ring is cyclodecanyl, cyclodecenyl, cyclodecadienyl, cyclodecatrienyl Each group such as enyl is exemplified.

  Preferably it is a 3-6 membered ring, More preferably, it is a 5-6 membered ring, Most preferably, it is a 6 membered ring, Among these, the hydrocarbon ring which does not contain a hetero atom is preferable. The ring may form a spiro bond with another ring through a spiro atom, or may be condensed in any way with another ring including an aromatic ring. Moreover, it can have an arbitrary substituent on the ring. Specific examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, etc.), an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, etc.), cycloalkyl group (for example, cyclohexyl group, cycloheptyl group, etc.), alkenyl group (for example, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl) -3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, etc.), cycloalkenyl group (eg 1-cycloalkenyl group, 2-cycloalkenyl group etc.), alkynyl group (eg ethynyl group, 1-propynyl group etc.), alkoxy group (eg methoxy group, ethoxy group, propoxy group etc.), alkylcarbonyloxy group For example, acetyloxy group etc.), alkylthio group (eg methylthio group, trifluoromethylthio group etc.), carboxyl group, alkylcarbonylamino group (eg acetylamino group etc.), ureido group (eg methylaminocarbonylamino group etc.) ), Alkylsulfonylamino groups (for example, methanesulfonylamino group, etc.), alkylsulfonyl groups (for example, methanesulfonyl group, trifluoromethanesulfonyl group, etc.), carbamoyl groups (for example, carbamoyl group, N, N-dimethylcarbamoyl group, N -Morpholinocarbonyl group, etc.), sulfamoyl group (sulfamoyl group, N, N-dimethylsulfamoyl group, morpholinosulfamoyl group, etc.), trifluoromethyl group, hydroxyl group, nitro group, cyano group, alkylsulfone Group (for example, methanesulfonamide group, butanesulfonamide group, etc.), alkylamino group (for example, amino group, N, N-dimethylamino group, N, N-diethylamino group, etc.), sulfo group, phosphono group, sulfite Group, sulfino group, alkylsulfonylaminocarbonyl group (eg, methanesulfonylaminocarbonyl group, ethanesulfonylaminocarbonyl group, etc.), alkylcarbonylaminosulfonyl group (eg, acetamidosulfonyl group, methoxyacetamidosulfonyl group, etc.), alkynylaminocarbonyl group (For example, acetamidocarbonyl group, methoxyacetamidocarbonyl group, etc.), alkylsulfinylaminocarbonyl group (for example, methanesulfinylaminocarbonyl group, ethanesulfinylaminocarbonyl group) Etc.). Moreover, when there are two or more substituents, they may be the same or different. A particularly preferred substituent is an alkyl group.

R ₀ ′ and R ₀ ″ represent a substitutable group on the benzene ring, and examples thereof include a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Specific examples of the alkyl group include those having 1 to 1 carbon atoms. It is preferably an alkyl group of 10. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group. Group, decyl group, cyclohexyl group, cycloheptyl group, 1-methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3- Examples thereof include a butenyl group, a 1-cycloalkenyl group, a 2-cycloalkenyl group, an ethynyl group, and a 1-propynyl group, and more preferably a methyl group and an ethyl group. , An isopropyl group, a t-butyl group, a cyclohexyl group, a 1-methylcyclohexyl group, etc. A methyl group, a t-butyl group, and a 1-methylcyclohexyl group are preferable, and a methyl group is most preferable. Specific examples include phenyl group, naphthyl group, anthranyl group, etc. Specific examples of the heterocyclic group include pyridine group, quinoline group, isoquinoline group, imidazole group, pyrazole group, triazole group, oxazole group, thiazole group, Aromatic heterocyclic groups such as oxadiazole group, thiadiazole group, and tetrazole group, and non-aromatic heterocyclic groups such as piperidino group, morpholino group, tetrahydrofuryl group, tetrahydrothienyl group, and tetrahydropyranyl group can be mentioned. The group may further have a substituent, The substituent groups include the substituent groups on the aforementioned ring. Multiple R ₀ ', R ₀ "may be the same or different, but all most preferably is the case of methyl group.

R _x represents a hydrogen atom or an alkyl group, and specifically, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, pentyl group, iso-pentyl group, 2-ethyl-hexyl group, octyl group, decyl group, cyclohexyl group, cycloheptyl. Group, 1-methylcyclohexyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl group, 1-cycloalkenyl group, 2 -A cycloalkenyl group, an ethynyl group, a 1-propynyl group, etc. are mentioned. More preferably, a methyl group, an ethyl group, an isopropyl group, etc. are mentioned. Preferably R _x is a hydrogen atom.

Q ₀ represents a substitutable group on the benzene ring, specifically, an alkyl group having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group). Cyclohexyl group, etc.), halogenated alkyl group (trifluoromethyl group, perfluorooctyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group etc.), alkynyl group (propargyl group etc.), glycidyl group, acrylate group, methacrylate Group, aryl group (phenyl group etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, sriphoranyl group, piperidinyl group, Pyrazolyl group, tetrazolyl group, etc.), halogen atom ( Elementary atom, bromine atom, iodine atom, fluorine atom, etc.), alkoxy group (methoxy group, ethoxy group, propyloxy group, pentyloxy group, cyclopentyloxy group, hexyloxy group, cyclohexyloxy group, etc.), aryloxy group (phenoxy) Group), alkoxycarbonyl group (methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group etc.), aryloxycarbonyl group (phenyloxycarbonyl group etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group) , Butanesulfonamide group, hexanesulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butyrate) Ruaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, phenylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), urethane group (methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, phenylureido group) 2-pyridylureido group), acyl group (acetyl group, propionyl group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethyl group) Aminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group Acetamide group, propionamide group, butanamide group, hexaneamide group, benzamide group, etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), Amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyridylamino group, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group, oxamoyl group, etc. Can be mentioned. These groups may be further substituted with these groups. n and m each represents an integer of 0 to 2, and most preferably n and m are 0.

  Specific examples of the compounds represented by the general formula (S) of the present invention are listed below.

  In the present invention, U.S. Pat. Nos. 3,589,903 and 4,021,249 or British Patent 1,486,148 and JP-A-51-51933, 50-36110, No. 50-11603, 52-84727 or JP-B 51-35727, such as 2,2′-dihydroxy-1,1′-binaphthyl, 6,6′-dibromo-2, Bisnaphthols described in U.S. Pat. No. 3,672,904 such as 2'-dihydroxy-1,1'-binaphthyl, and further, for example, 4-benzenesulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, U.S. Pat. Sulfonamidophenols or sulfonamidonaphthols, such as described in 01,321 Pat also can be used as the silver ion reducing agent.

The amount of the reducing agent including the compounds represented by the general formulas (A) and (S) is preferably 1 × 10 ⁻² to 10 mol, particularly 1 × 10 ⁻² to 1 mol per mol of silver. .5 moles.

  The amount of the reducing agent used in the photothermographic dry imaging material varies depending on the type of organic silver salt, reducing agent, and other additives, but generally 0.05 to 10 mol per mol of organic silver salt. 0.1 mol to 3 mol is preferable. In addition, within the range of this amount, two or more of the reducing agents described above may be used in combination. In the present invention, it may be preferable that the reducing agent is added to and mixed with a photosensitive emulsion solution composed of photosensitive silver halide and organic silver salt grains and a solvent immediately before coating, because photographic performance fluctuation due to stagnation time is small. is there.

  In addition, as an auxiliary agent for the reducing agent, a compound capable of forming a hydrogen bond with a hydrogen atom of the hydroxyl group of the reducing agent, such as triphenylphosphine oxide described in EP1,096,310, may be used in combination. preferable.

[Photosensitive silver halide grains]
Photosensitive silver halide grains (also referred to simply as silver halide grains) used in the silver salt photothermographic dry imaging material of the present invention (also referred to simply as the light-sensitive material of the present invention) will be described. The photosensitive silver halide grains in the present invention can inherently absorb light as an intrinsic property of silver halide crystals, or artificially physicochemically emit visible light or infrared light. Physicochemical change in the silver halide crystal and / or on the crystal surface when absorbing light in any region within the light wavelength range from the ultraviolet light region to the infrared light region. Refers to silver halide crystal grains that have been processed and produced so that can occur.

  The silver halide grains themselves used in the present invention are P.I. Chifie et Physique Photographic (published by Paul Montel, 1967) by Glafkides. F. Duffin's Photographic Emission Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared as a silver halide grain emulsion using the method described in Making and Coating Photographic Emulsion (published by The Focal Press, 1964) by Zelikman et al.

  That is, any of an acidic method, a neutral method, an ammonia method, etc. may be used, and the formation of reacting a soluble silver salt and a soluble halogen salt may be any one of a one-side mixing method, a simultaneous mixing method, and a combination thereof. Of these methods, the so-called controlled double jet method, in which silver halide grains are prepared while controlling the formation conditions, is preferred. The halogen composition is not particularly limited and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide, but for medical imaging materials. Silver bromide or silver iodobromide is preferred. In the case of silver iodobromide, the content of iodine is preferably in the range of 0.02 mol% to 6 mol% per mol of Ag. Even if the iodine is contained so as to be distributed throughout the silver halide grains, the concentration of iodine at a specific portion of the silver halide grains, for example, the central portion of the grains is increased and the concentration in the vicinity of the surface is decreased or substantially zero. Such a core / shell structure may be used.

  Grain formation is usually divided into two stages: silver halide seed grain (nucleus) generation and grain growth, and these may be performed continuously at one time. Alternatively, the nucleus (seed grain) formation and grain growth may be separated. The method of performing may be used. The controlled double jet method in which the particle formation is controlled by controlling the pAg, pH, etc., which are particle formation conditions, is preferable because the particle shape and size can be controlled. For example, when performing a method of separating nucleation and grain growth, first, soluble silver salt and soluble halogen salt are uniformly and rapidly mixed in an aqueous gelatin solution to produce nuclei (seed grains) (nucleation process). Thereafter, silver halide grains are prepared by a grain growth process in which grains are grown while supplying a soluble silver salt and a soluble halogen salt under controlled pAg, pH and the like. After the formation of the grains, the desired salt halide emulsion can be obtained by removing unnecessary salts by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, or an electrodialysis method. I can do it.

  The silver halide grains used in the present invention are preferably mixed with different grain sizes, and the average grain size is 0.040 μm or less and / or as a value when grains having a particle size of less than 0.02 μm are excluded from measurement. The number of silver halide grains of 0.070 to 0.100 μm is preferably in the range of 10 to 30% of the whole. The grain size here means the length of the edge of the silver halide grain when the silver halide grain is a so-called normal crystal of a cube or octahedron. Further, when the silver halide grain is a tabular grain, it means the diameter when converted into a circular image having the same area as the projected area of the main surface.

  In the present invention, the silver halide grains are preferably monodispersed. The term “monodispersed” as used herein means that the coefficient of variation of the particle diameter obtained by the following formula is 30% or less. Preferably it is 20% or less, More preferably, it is 15% or less.

Coefficient of variation of particle size% = (standard deviation of particle size / average value of particle size) × 100
Examples of the shape of the silver halide grains include cubes, octahedrons, tetradecahedral grains, tabular grains, spherical grains, rod-like grains, and potato-like grains. Among these, cubic, octahedral, and tetrahedral Tabular silver halide grains are preferred.

  When tabular silver halide grains are used, the average aspect ratio is preferably 1.5 or more and 100 or less, more preferably 2 or more and 50 or less. These are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958 and the like, and the desired tabular grains can be easily obtained. Further, grains having rounded corners of silver halide grains can be preferably used.

  There is no particular limitation on the crystal habit on the outer surface of the silver halide grain, but when using a spectral sensitizing dye having crystal habit (plane) selectivity in the adsorption reaction of the silver sensitizing dye on the surface of the silver halide grain It is preferable to use silver halide grains having a relatively high proportion of crystal habits adapted to the selectivity. For example, when using a sensitizing dye that is selectively adsorbed on the crystal face of the Miller index [100], the proportion of the [100] face on the outer surface of the silver halide grain is preferably high, and this ratio is 50 % Or more, more preferably 70% or more, and particularly preferably 80% or more. The ratio of the Miller index [100] plane is a T.K. based on the adsorption dependency of the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985).

  The silver halide grains used in the present invention are preferably prepared using low molecular weight gelatin having an average molecular weight of 50,000 or less at the time of forming the grains, and particularly preferably used at the time of nucleation of silver halide grains. The low molecular weight gelatin has an average molecular weight of 50,000 or less, preferably 2000 to 40000, more preferably 5000 to 25000. The average molecular weight of gelatin can be measured by gel filtration chromatography. Low molecular weight gelatin can be decomposed by adding gelatin-degrading enzyme to a commonly used gelatin aqueous solution with an average molecular weight of about 100,000, hydrolyzing by adding acid or alkali, and heating under atmospheric pressure or pressure. Can be obtained by thermal decomposition, decomposition by ultrasonic irradiation, or a combination of these methods.

  The concentration of the dispersion medium at the time of nucleation is preferably 5% by mass or less, and it is more effective to carry out at a low concentration of 0.05 to 3.0% by mass.

  For the silver halide grains used in the present invention, it is preferable to use a polyethylene oxide compound represented by the following general formula when the grains are formed.

General formula (K)
YO (CH ₂ CH ₂ O) _m (CH (CH ₃ ) CH ₂ O) _p (CH ₂ CH ₂ O) _n Y
In the formula, Y represents a hydrogen atom, —SO ₃ M, or —CO—B—COOM, and M represents an ammonium group substituted with a hydrogen atom, an alkali metal atom, an ammonium group, or an alkyl group having 5 or less carbon atoms. And B represents a chain or cyclic group forming an organic dibasic acid. m and n each represents 0 to 50, and p represents 1 to 100.

  The polyethylene oxide compound represented by the above general formula comprises a step of producing a gelatin aqueous solution, a step of adding a water-soluble halide and a water-soluble silver salt to the gelatin solution, and an emulsion. It has been preferably used as an antifoaming agent for significant foaming when the emulsion raw material is stirred or moved, such as a step of coating on a support. 44-9497. The polyethylene oxide compound represented by the above general formula also functions as an antifoaming agent during nucleation.

  The polyethylene oxide compound represented by the above general formula is preferably used at 1% by mass or less, more preferably 0.01 to 0.1% by mass with respect to silver.

  The polyethylene oxide compound represented by the above general formula may be present at the time of nucleation and is preferably added in advance to the dispersion medium before nucleation, but may be added during nucleation or You may add and use for the silver salt aqueous solution and halide aqueous solution which are used at the time of formation. Preferably, it is used by adding 0.01 to 2.0% by mass to the aqueous halide solution or both aqueous solutions. Further, it is preferable to exist for at least 50% of the nucleation step, and more preferably for 70% or more. The polyethylene oxide compound represented by the above general formula may be added as a powder or dissolved in a solvent such as methanol.

  The temperature at the time of nucleation is 5 to 60 ° C., preferably 15 to 50 ° C. Even if the temperature is constant, the temperature rising pattern (for example, the temperature at the start of nucleation is 25 ° C. It is preferable to control the temperature within the above temperature range even when the temperature is gradually raised and the temperature at the end of nucleation is 40 ° C.) and vice versa.

The concentration of the silver salt aqueous solution and halide aqueous solution used for nucleation is preferably 3.5 M (mol) / L (liter) or less, and more preferably used in a low concentration range of 0.01 to 2.5 M / L. . The addition rate of silver ions during nucleation is preferably 1.5 × 10 ^{−3 to} 3.0 × 10 ⁻¹ mol / min, more preferably 3.0 × 10 ^{−3 to} 8.0, per liter of the reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can be set in the range of 1.7 to 10, but the pH on the alkali side is preferably pH 2 to 6 in order to broaden the particle size distribution of nuclei to be formed. Moreover, pBr at the time of nucleation is about 0.05 to 3.0, preferably 1.0 to 2.5, and more preferably 1.5 to 2.0.

  In the present invention, it is preferable from the viewpoint of sensitivity and image preservability that a heterocyclic compound is contained inside the silver halide grains after nucleation. The heterocyclic compounds used here include imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiadiazole, oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline , Pteridine, acridine, phenanthroline, phenazine, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzthiazole, indolenine, tetrazaindene, preferably imidazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, thiadiazole Oxadiazole, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinno Emissions, tetrazole, thiazole, oxazole, benzimidazole, benzoxazole, benzthiazole, a tetrazaindene.

  The heterocyclic compound may have a substituent, and the substituent is preferably an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an acyl group, an alkoxycarbonyl group, Aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, sulfonyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, sulfo Group, carboxyl group, nitro group, heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryloxy group, acyl group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonyl Mino group, sulfamoyl group, carbamoyl group, ureido group, phosphoric acid amide group, halogen atom, cyano group, nitro group, heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryloxy group, acyl group An acylamino group, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, a halogen atom, a cyano group, a nitro group, or a heterocyclic group.

  The silver halide grains of the present invention may be added to the photosensitive layer (also referred to simply as the photosensitive layer) by any method. At this time, the silver halide grains are close to a reducible silver source (aliphatic carboxylic acid silver salt). It is preferable to arrange so as to.

  The silver halide of the present invention is prepared in advance, and this is added to a solution for preparing aliphatic carboxylic acid silver salt grains. Although it can be handled separately, it is preferable for production control. However, as described in British Patent No. 1,447,454, when preparing aliphatic carboxylic acid silver salt particles, halogen components such as halide ions are aliphatic. By coexisting with the carboxylate silver salt-forming component and injecting silver ions into this, it can be produced almost simultaneously with the production of the aliphatic carboxylate silver salt particles. It is also possible to prepare silver halide grains by converting a halogen-containing silver salt into an aliphatic carboxylic acid silver salt and converting the aliphatic carboxylic acid silver salt. That is, a silver halide-forming component is allowed to act on a solution or dispersion of an aliphatic carboxylic acid silver salt prepared in advance, or a sheet material containing the aliphatic carboxylic acid silver salt, so that a part of the aliphatic carboxylic acid silver salt is removed. It can also be converted to photosensitive silver halide.

  However, the photosensitive silver halide grain of the present invention refers to a silver halide grain prepared in advance separately from the fatty carboxylic acid silver salt, without being directly related to the fatty carboxylic acid silver salt.

  Examples of silver halide grain forming components include inorganic halogen compounds, onium halides, halogenated hydrocarbons, N-halogen compounds, and other halogen-containing compounds. Specific examples thereof are described in US Pat. No. 4,009,039. No. 3,457,075, No. 4,003,749, British Patent No. 1,498,956 and JP-A Nos. 53-27027 and 53-25420. Inorganic halides such as ammonium, for example, onium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, trimethylbenzylammonium bromide, such as iodoform, bromoform, carbon tetrachloride, 2-bromo-2-methylpropane, etc. Halogenated hydrocarbons of -N-halogen compounds such as bromosuccinimide, N-bromophthalimide, N-bromoacetamide, and others, such as triphenylmethyl chloride, triphenylmethyl bromide, 2-bromoacetic acid, 2-bromoethanol, dichlorobenzophenone, etc. is there. Thus, the silver halide can also be prepared by converting a part or all of silver in the organic acid silver salt into silver halide by the reaction between the organic acid silver and the halogen ion. Moreover, you may use together the silver halide grain manufactured by converting a part of aliphatic carboxylic acid silver salt into the silver halide prepared separately.

  These silver halide grains are separately prepared silver halide grains, 0.001 to 0.7 mol per 1 mol of aliphatic carboxylic acid silver salt, and silver halide grains obtained by conversion of aliphatic carboxylic acid silver salt. Preferably 0.03-0.5 mol is used.

The silver halide grains used in the present invention preferably contain transition metal ions belonging to Groups 6 to 11 of the Periodic Table of Elements. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable. These may be used alone or in combination of two or more of the same or different metal complexes. Although these metal ions may introduce a metal salt into silver halide as it is, they can be introduced into silver halide in the form of a metal complex or complex ion. The preferred content is in the range of 1 × 10 ⁻⁹ mol to 1 × 10 ⁻² mol, and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻⁴ with ^respect to 1 mol of silver. In the present invention, the transition metal complex or complex ion is preferably represented by the following general formula.

General formula [ML ₆ ] ^m
In the formula, M is a transition metal selected from Group 6 to 11 elements of the periodic table, and Os and Ru are particularly preferable. L represents a ligand, and m represents 0,-, 2-, 3- or 4-. Specific examples of the ligand represented by L include halogen ion (fluorine ion, chlorine ion, bromine ion, iodine ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide, and aco. A ligand, nitrosyl, thionitrosyl and the like can be mentioned, and ako, nitrosyl, thionitrosyl and the like are preferable. When an acoligand is present, it preferably occupies one or two of the ligands. L may be the same or different.

  The compounds providing these metal ions or complex ions 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 , May be added at any stage before or after chemical sensitization, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Preferably, it is added at the stage of nucleation. In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in JP-A Nos. 167545, 4-76534, 6-110146, 5-273683, etc., the particles can be contained with a distribution.

  These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or the silver salt solution and the halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a method of simultaneous mixing of three liquids, a method of introducing an aqueous solution of a required amount of a metal compound into a reaction vessel during grain formation, or a silver halide preparation There is a method of adding and dissolving another silver halide grain that has been previously doped with metal ions or complex ions. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution. When added to the particle surface, a necessary amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or after the physical ripening, or at the chemical ripening.

  Separately prepared photosensitive silver halide grains can be desalted by a known desalting method such as noodle method, flocculation method, ultrafiltration method, electrodialysis method, etc., but can also be used without desalting. .

  In the present invention, the grain size of silver halide grains can be arbitrarily controlled by a method known in the photographic industry, such as changing the temperature and growth time during growth after nucleation.

[Aliphatic carboxylic acid silver salt]
The aliphatic carboxylic acid silver salt is a reducible silver source, and a silver salt of an aliphatic carboxylic acid having 10 to 30, preferably 15 to 25 carbon atoms is preferable. Examples of suitable silver salts include the following.

  Silver salts such as gallic acid, succinic acid, behenic acid, stearic acid, arachidic acid, palmitic acid and lauric acid. Among these, preferable silver salts include silver behenate, silver arachidate, and silver stearate. In the present invention, it is preferable that two or more types of aliphatic carboxylic acid silver salts are mixed in order to improve developability and form a silver image having a high density and a high contrast. For example, two or more types of aliphatic carboxylic acid salts are used. The acid mixture is preferably prepared by mixing a silver ion solution, but the molar ratio of silver behenate is preferably 80% or more.

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

  In the aliphatic carboxylic acid silver salt, the average equivalent circle diameter is 0.05 μm or more and 0.8 μm or less, and the average thickness is preferably 0.005 μm or more and 0.07 μm or less, particularly preferably the average circle. The equivalent diameter is 0.2 μm or more and 0.5 μm, and the average thickness is 0.01 μm or more and 0.05 μm or less.

  When the average equivalent circle diameter is 0.05 μm or less, the transparency is excellent, but the image storage stability is poor, and when the average equivalent circle diameter is 0.8 μm or more, devitrification is severe. When the average thickness is 0.005 μm or less, the surface area is large, and silver ions are rapidly supplied during development. In particular, the low density area is not used for silver images, and there is a large amount of silver ions remaining in the film. The image storage stability is significantly deteriorated. When the average thickness is 0.07 μm or more, the surface area is reduced and the image stability is improved. However, the silver supply during development is slow, resulting in unevenness of the developed silver shape particularly in the high density portion, resulting in the highest density. It tends to be low.

  To obtain the average equivalent circle diameter, the dispersed aliphatic carboxylic acid silver salt is diluted and dispersed on a grid with a carbon support film, and the transmission electron microscope (manufactured by JEOL Ltd., 2000FX type) is directly increased to 5000 times magnification. I took a picture. The negative is captured as a digital image with a scanner, and 300 or more particle sizes (equivalent circle diameter) are measured using appropriate image processing software, and the average particle size is calculated.

  The average thickness is calculated by a method using a TEM (transmission electron microscope) as shown below.

  First, the photosensitive layer coated on the support is attached to an appropriate holder with an adhesive, and an ultrathin slice having a thickness of 0.1 to 0.2 μm is produced using a diamond knife in a direction perpendicular to the support surface. . The prepared ultra-thin slice is supported on a copper mesh, transferred onto a carbon film that has been hydrophilized by glow discharge, and cooled with liquid nitrogen to −130 ° C. or lower using a transmission electron microscope (hereinafter referred to as TEM). The bright field image is observed at a magnification of 5,000 to 40,000, and the image is quickly recorded on a film, an imaging plate, a CCD camera or the like. At this time, it is preferable to appropriately select a portion where the section is not torn or slack as the field of view to be observed.

  As the carbon film, it is preferable to use a very thin collodion, formbar, or the like supported by an organic film. More preferably, the carbon film is formed on a rock salt substrate and dissolved and removed. It is a carbon-only film obtained by solvent and ion etching. The acceleration voltage of TEM is preferably 80 to 400 kV, particularly preferably 80 to 200 kV.

  In addition, for details of electron microscope observation techniques and sample preparation techniques, see “The Japan Electron Microscopy Society Kanto Branch / Medical and Biological Electron Microscopy” (Maruzen), “The Japan Electron Microscopy Society Kanto Branch / Electron Microscope Biological Samples” "Manufacturing method" (Maruzen) can be referred to respectively.

  A TEM image recorded on an appropriate medium is preferably decomposed into at least 1024 pixels × 1024 pixels, preferably 2048 pixels × 2048 pixels or more, and image processing by a computer is performed. In order to perform image processing, it is preferable that an analog image recorded on a film is converted into a digital image by a scanner or the like, and shading correction, contrast / edge enhancement, and the like are performed as necessary. Thereafter, a histogram is prepared, and a portion corresponding to the aliphatic carboxylate silver is extracted by binarization processing.

  300 or more of the extracted aliphatic carboxylic acid silver salt particles are manually measured with appropriate software to obtain an average value.

  The method for obtaining the aliphatic carboxylic acid silver salt particles having the above-mentioned shape is not particularly limited, but the mixed state at the time of forming the organic acid alkali metal salt soap and / or the mixed state at the time of adding silver nitrate to the soap, etc. It is effective to maintain a good balance, optimize the ratio of organic acid to soap, and the ratio of silver nitrate that reacts with soap.

  The aliphatic carboxylic acid silver salt particles are preferably preliminarily dispersed together with a binder, a surfactant or 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 rotating centrifugal radiation type stirrer (dissolver), or a high speed rotating shear type stirrer (homomixer) can be used.

  In addition, as the media dispersing machine, a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill that is a medium stirring mill, an attritor, and other basket mills can be used, and a wall as a high-pressure homogenizer. Various types can be used, such as a type that collides with a plug or the like, a type in which liquids are collided at a high speed after dividing the liquid, and a type in which a thin orifice is passed.

Examples of ceramics used for the ceramic beads used when dispersing the media include Al ₂ O ₃ , BaTiO ₃ , SrTiO ₃ , MgO, ZrO, BeO, Cr ₂ O ₃ , SiO ₂ , SiO ₂ —Al ₂ O ₃ , Cr. ₂ O ₃ —MgO, MgO—CaO, MgO—C, MgO—Al ₂ O ₃ (spinel), SiC, TiO ₂ , K ₂ O, Na ₂ O, BaO, PbO, B ₂ O ₃ , SrTiO ₃ (titanium) _{strontium), BeAl 2 O 4, Y} 3 Al 5 O 12, ZrO 2 -Y 2 O 3 ( cubic _{zirconia), 3BeO-Al 2 O 3} -6SiO 2 ( synthesis emerald), C (diamond), Si ₂ O—nH ₂ O, ticker silicon, yttrium-stabilized zirconia, zirconia-reinforced alumina, and the like are preferable.

  Yttrium-stabilized zirconia and zirconia-reinforced alumina (ceramics containing these zirconia are hereinafter abbreviated as zirconia) are particularly preferably used because of the low generation of impurities due to friction with beads and dispersers during dispersion.

  In the apparatus used when dispersing the aliphatic carboxylic acid silver salt particles, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond is used as the material of the member in contact with the aliphatic carboxylic acid silver salt particles. It is preferable to use zirconia. When the above dispersion is performed, the binder concentration is preferably added in an amount of 0.1 to 10% of the mass of the aliphatic silver carboxylate, and it is preferable that the liquid temperature does not exceed 45 ° C. from the preliminary dispersion through the main dispersion. As preferable operating conditions for the present dispersion, for example, when a high-pressure homogenizer is used as the dispersing means, the preferable operating conditions are 29.42 to 98.06 MPa, and the number of operations is preferably 2 times or more. Moreover, when using a media disperser as a dispersion | distribution means, 6-13 m / sec of peripheral speed is mentioned as preferable conditions.

  In the present invention, the compound functioning as a crystal growth inhibitor or dispersant for the aliphatic carboxylic acid silver salt particles means an aliphatic carboxylic acid under the condition in which the compound is present in the production process of the aliphatic carboxylic acid silver salt particles. This refers to a compound having a function and an effect of reducing the particle size and monodispersing when silver oxide is produced under conditions where it does not coexist. Specific examples include monohydric alcohols having 10 or less carbon atoms, preferably secondary alcohols, tertiary alcohols, glycols such as ethylene glycol and propylene glycol, polyethers such as polyethylene glycol, and glycerin. A preferable addition amount is 10 to 200% by mass with respect to the aliphatic carboxylate silver.

  On the other hand, branched aliphatic carboxylic acids containing isomers such as isoheptanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, isopalmitic acid, isostearic acid, isoarachidic acid, isobehenic acid and isohexaconic acid are also preferred. In this case, a preferable side chain includes an alkyl group or alkenyl group having 4 or less carbon atoms. In addition, aliphatic unsaturated carboxylic acids such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, moloctic acid, eicosenoic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosapentaenoic acid, docosahexaenoic acid, and ceracolonic acid It is done. A preferable addition amount is 0.5 to 10 mol% of the silver aliphatic carboxylate.

  Glycosides such as glucoside, galactoside and fructoside, trehalose type disaccharides such as trehalose and sucrose, polysaccharides such as glycogen, dextrin, dextran and alginic acid, cellosolves such as methyl cellosolve and ethyl cellosolve, sorbitan, sorbit, ethyl acetate and acetic acid Water-soluble organic solvents such as methyl and dimethylformamide, water-soluble polymers such as polyvinyl alcohol, polyacrylic acid, acrylic acid copolymer, maleic acid copolymer, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone and gelatin Are also preferred compounds. A preferable addition amount is 0.1 to 20% by mass with respect to the aliphatic carboxylate silver.

  Alcohols having 10 or less carbon atoms, preferably secondary alcohols and tertiary alcohols are monodispersed and small in viscosity by increasing the solubility of sodium aliphatic carboxylate in the charging step and increasing the stirring efficiency. Grain size. Branched aliphatic carboxylic acids and aliphatic unsaturated carboxylic acids have higher steric hindrance than the main component linear aliphatic carboxylic acid silver when crystallization of the aliphatic carboxylic acid silver, and the disorder of the crystal lattice is large. Therefore, large crystals are not generated, and as a result, the particle size is reduced.

  As described above, compared with the conventional silver halide photographic light-sensitive material, the biggest difference in the structure of the silver salt photothermographic dry imaging material is that the latter material, before and after the development processing, That is, it contains a large amount of photosensitive silver halide, organic silver salt and reducing agent that may cause fogging and printout silver (baked-out silver). For this reason, silver salt photothermographic dry imaging materials require advanced antifogging and image stabilization techniques in order to maintain storage stability not only before development but also after development. In addition to aromatic heterocyclic compounds that inhibit growth and development, mercury compounds such as mercury acetate, which have the function of oxidizing and extinguishing fog nuclei, have been used as very effective storage stabilizers. The use of mercury compounds has been a problem in terms of safety and environmental conservation.

[Toning agent]
It is desirable to use a toning agent in the silver salt photothermographic dry imaging material of the present invention. Examples of suitable toning agents that can be used are Research Disclosure No. 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, and 4, For example, there are the followings.

  Imides (for example, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide); mercaptans (for example, 3-mercapto-1,2,4-triazole); phthalazinone derivatives or metal salts of these derivatives ( For example, phthalazinone, 4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); phthalazine and phthalic acids ( For example, a combination of phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic acid); phthalazine and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylene acid derivative and its anhydride Products (eg, phthalic acid, 4-methylphthalic acid, 4 A combination of at least one compound selected from nitrophthalic acid and tetrachlorophthalic anhydride) and the like. Particularly preferred color tones are phthalazinone or a combination of phthalazine and phthalic acids and phthalic anhydrides.

  In particular, in the present invention, a carboxylic acid such as phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, tetrachlorophthalic anhydride, benzoic acid, 4-methylbenzoic acid, 4-nitrobenzoic acid and pentachlorobenzoic acid is used. The compound to be contained is preferably contained in a non-photosensitive layer adjacent to the photosensitive layer. More preferably, it is contained in the non-photosensitive layer opposite to the support with respect to the photosensitive layer.

  The amount of the compound containing a carboxylic acid group contained in the non-photosensitive layer is preferably 0.005 to 0.20 mol / Ag mol, and more preferably 0.01 to 0.10 mol / Ag. Is a mole.

  Note that, regarding the color tone of an output image for conventional medical diagnosis, it is said that a cold tone image tone is easier for a reader of an X-ray photograph to obtain a more accurate diagnosis observation result of a recorded image. Here, the cool image tone is a pure black tone or a bluish black tone with a black image, and the warm image tone is a warm black tone with a brown image on a black image. Say.

The terms “more cold” and “more warm” regarding the color tone are determined by the hue angle hab at the minimum density Dmin and the optical density D = 1.0. The hue angle hab is calculated using the color coordinates a ^* and b ^* of the color space L ^* a ^* b ^* color space, which is a color space having a perceptually uniform rate recommended in 1976 by the International Commission on Illumination (CIE). It is calculated by the following formula.

hab = tan ⁻¹ (b ^* / a)
In the present invention, the preferred range of hab is 180 ° <hab <270 °, more preferably 200 ° <hab <270 °, and most preferably 220 ° <hab <260 °.

[Anti-fogging and image stabilizer]
In the silver salt photothermographic dry imaging material of the present invention, as a reducing agent, a reducing agent of bisphenols is mainly used. Therefore, the reducing agent is not generated by generating active species capable of extracting these hydrogens. It is preferable that the compound which can be activated is contained. A colorless photo-oxidizable substance is preferably a compound capable of generating free radicals as reactive active species during exposure.

  Accordingly, any compound having these functions may be used, but an organic free radical composed of a plurality of atoms is preferred. A compound having any structure may be used as long as it has such a function and does not cause any particular adverse effects on the silver salt photothermographic dry imaging material.

  In addition, these free radical-generating compounds are carbocyclic or heterocyclic in order to give the generated free radicals stable enough to be in contact with the reducing agent for a sufficient time to inactivate. Those having the following aromatic group are preferred.

  Representative examples of these compounds include biimidazolyl compounds and iodonium compounds listed below. For example, a biimidazolyl compound can be produced by the production method described in US Pat. No. 3,734,733 and British Patent No. 1,271,177 and a method analogous thereto.

  As a preferable specific example, the compound example described in Unexamined-Japanese-Patent No. 2000-321711 can be mentioned, for example.

  Similarly, iodonium compounds can be cited as suitable compounds. Iodonium compounds are described in Org. Syn. , 1961 and "Advanced Organic Chemistry by Fieser" (Reinhold, NY, 1961) and a method analogous thereto.

  As a preferable specific example, the compound example described in Unexamined-Japanese-Patent No. 2000-321711 can be mentioned, for example.

The addition amount of these compounds is 10 ⁻³ to 10 ⁻¹ mol / m ² , preferably 5 × 10 ^{−3 to} 5 × 10 ⁻² mol / m ² . The compound can be contained in any constituent layer in the light-sensitive material of the present invention, but is preferably contained in the vicinity of the reducing agent.

  Further, as a compound that inactivates the reducing agent and prevents the reducing agent from reducing the aliphatic carboxylic acid silver salt to silver, a compound in which the reactive species is not a halogen atom is preferable, but a compound that releases a halogen atom as an active species is also available. Can be used in combination with a compound that releases an active species that is not a halogen atom. Many compounds capable of releasing a halogen atom as an active species are known, and a good effect can be obtained by the combined use.

  Specific examples of the compound that generates these active halogen atoms include 4-1 to 4-64 described in JP-A No. 2001-249428.

  The amount of these compounds added is preferably within a range in which the increase in printout silver due to the formation of silver halide does not become a problem, and the ratio to the compound that does not generate active halogen radicals is 150% or less, more preferably It is preferable that it is 100% or less.

  In addition to the above compound, the silver salt photothermographic dry imaging material of the present invention may contain a compound conventionally known as an antifoggant, but the reactive species similar to the above compound Even if it is a compound which can produce | generate, the compound from which an antifogging mechanism differs may be sufficient. For example, U.S. Pat. Nos. 3,589,903, 4,546,075, 4,452,885, JP-A-59-57234, U.S. Pat. No. 3,874,946, 4,756. , 999, JP-A-9-288328, and JP-A-9-90550. Further, other antifoggants include compounds disclosed in US Pat. No. 5,028,523 and European Patents 600,587, 605,981, and 631,176.

  It is preferable to use a thiosulfonic acid compound represented by the following general formula (B) in combination as long as the effects of the present invention are not impaired.

Formula (B) R ¹ —SO ₂ SM ¹
In the formula, R ¹ may be the same or different, and represents an aliphatic group, an aromatic group, or a heterocyclic group, and M ¹ represents a cation.

When R ¹ is an aliphatic group, it is preferably an alkyl group having 1 to 22 carbon atoms, an alkenyl group having 2 to 22 carbon atoms, or an alkynyl group, which may have a substituent. Examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, isopropyl and t-butyl. Examples of the alkenyl group include allyl and butenyl. Examples of the alkynyl group include propargyl and butynyl.

The aromatic group for R ¹ preferably has 6 to 20 carbon atoms, and examples thereof include phenyl and naphthyl. These may be substituted.

The heterocyclic group for R ¹ is a 3- to 15-membered ring having at least one element selected from nitrogen, oxygen, sulfur, selenium, and tellurium, such as a pyrrolidine ring, piperidine ring, pyridine ring, tetrahydrofuran ring, thiophene. Ring, oxazole ring, thiazole ring, imidazole ring, benzothiazole ring, benzoxazole ring, benzimidazole ring, selenazole ring, benzoselenazole ring, tellurazole ring, triazole ring, benzotriazole ring, tetrazole ring, oxadiazole ring, thiadiazole A ring is raised.

Examples of the substituent for R ¹ include an alkyl group (eg, methyl, ethyl, hexyl), an alkoxy group (eg, methoxy, ethoxy, octyl), an aryl group (eg, phenyl, naphthyl, tolyl), a hydroxy group, a halogen atom (fluorine, Chlorine, bromine, iodine), aryloxy group (phenoxy group), alkylthio group (methylthio group, butylthio group), arylthio group (phenylthio), acyl group (acetyl, propionyl, butyryl, valeryl), sulfonyl group (methylsulfonyl, phenyl) Sulfonyl), acylamino groups (acetylamino, benzamino, etc.), sulfonylamino groups (methanesulfonylamino, benzenesulfonylamino, etc.), acyloxy groups (acetoxy, benzoxy, etc.), carboxyl groups, cyano groups, sulfo groups, amino groups It is.

M ¹ is preferably a metal ion or an organic cation. Examples of the metal ion include lithium ion, sodium ion, and potassium ion. Examples of the organic cation include an ammonium ion (for example, animonium, tetramethylammonium, tetrabutylammonium), a phosphonium ion (tetraphenylphosphonium), and a guanidyl group.

The compound represented by the general formula (B) can be added to the emulsion at any stage of silver salt grain formation, before or after chemical ripening, and immediately before coating. The preferred addition time is after chemical sensitization or spectral sensitization and immediately before coating. A preferable addition amount is 1 × 10 ⁻⁵ to 1 mol / Ag mol, and more preferably 1 × 10 ⁻³ to 1 × 0.1 mol / Ag mol.

[Chemical sensitization]
The photosensitive silver halide grain in the present invention is preferably subjected to chemical sensitization. For example, use of a compound that releases a chalcogen such as sulfur, selenium, tellurium, or a noble metal ion that releases a noble metal ion such as gold ion by the methods described in JP-A Nos. 2001-249428 and 2001-249426 Can form and impart a chemical sensitization center (chemical sensitization nucleus). In particular, it is preferably chemically sensitized with an organic sensitizer containing a chalcogen atom.

  These organic sensitizers containing chalcogen atoms are preferably compounds having groups capable of adsorbing to silver halide and unstable chalcogen atom sites.

  As these organic sensitizers, organic sensitizers having various structures disclosed in JP-A-60-150046, JP-A-4-109240, JP-A-11-218874, and the like can be used. Of these, at least one compound having a structure in which a chalcogen atom is bonded to a carbon atom or a phosphorus atom by a double bond is preferable.

The amount of the chalcogen compound used as the organic sensitizer varies depending on the chalcogen compound used, silver halide grains, reaction environment for chemical sensitization, etc., but is 10 ⁻⁸ to 10 ⁻ per mol of silver halide. ² mol is preferred, more preferably 10 ⁻⁷ to 10 ⁻³ mol. The chemical sensitization environment is not particularly limited, but in the presence of a compound capable of annihilating or reducing the size of silver chalcogenide or silver nuclei on photosensitive silver halide grains, and in particular oxidizing silver nuclei. It is preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the presence of an oxidant that can be used. As the sensitization condition, pAg is preferably 6 to 11, more preferably 7 to The pH is preferably 4 to 10, more preferably 5 to 8, and the temperature is preferably 30 ° C. or lower for sensitization.

  Therefore, in the silver salt photothermographic dry imaging material of the present invention, the photosensitive silver halide uses an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei on the grain. It is preferable to use a photosensitive emulsion which has been chemically sensitized at a temperature of 30 ° C. or lower, mixed with an aliphatic carboxylic acid silver salt, dispersed, dehydrated and dried.

  In addition, chemical sensitization using these organic sensitizers is preferably performed in the presence of a heteroatom-containing compound having adsorptivity to spectral sensitizing dyes or silver halide grains. By performing chemical sensitization in the presence of a compound having an adsorptivity to silver halide, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved. Although the spectral sensitizing dye will be described later, preferred examples of the heteroatom-containing compound having adsorptivity to silver halide include nitrogen-containing heterocyclic compounds described in JP-A-3-24537. In the nitrogen-containing heterocyclic compound, the heterocyclic ring includes pyrazole ring, pyrimidine ring, 1,2,4-triazole ring, 1,2,3-triazole ring, 1,3,4-thiadiazole ring, 1,2,3- Thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,3,4-tetrazole ring, pyridazine ring, 1,2,3-triazine ring, Examples thereof include three bonded rings such as a triazolotriazole ring, a diazaindene ring, a triazaindene ring, and a pentaazaindene ring. A heterocyclic ring in which a monocyclic heterocyclic ring and an aromatic ring are condensed, for example, a phthalazine ring, a benzimidazole ring, an indazole ring, a benzthiazole ring, or the like can also be applied.

  Of these, an azaindene ring is preferable, and an azaindene compound having a hydroxyl group as a substituent, for example, a hydroxytriazaindene, a tetrahydroxyazaindene, a hydroxypentaazaindene compound, or the like is more preferable.

  The heterocyclic ring may have a substituent other than the hydroxyl group. Examples of the substituent include an alkyl group, a substituted alkyl group, an alkylthio group, an amino group, a hydroxyamino group, an alkylamino group, a dialkylamino group, an arylamino group, a carboxyl group, an alkoxycarbonyl group, a halogen atom, and a cyano group. May be.

The amount of these heterocyclic compounds added varies over a wide range depending on the size, composition, and other conditions of the silver halide grains, but the approximate amount is 10 ⁻⁶ per mole of silver halide. It is the range of -1.0 mol, Preferably it is the range of 10 ^<-4 > ^-10 < ^-1 > mol.

  The photosensitive silver halide of the present invention can be subjected to noble metal sensitization using a compound that releases noble metal ions such as gold ions. For example, a chloroaurate or an organic gold compound can be used as a gold sensitizer.

  In addition to the above-described sensitization methods, reduction sensitization methods and the like can also be used. Examples of shell-like compounds for reduction sensitization include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, and borane compounds. A silane compound, a polyamine compound, or the like can be used. Further, reduction sensitization can be performed by ripening the emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower.

  The silver halide subjected to chemical sensitization according to the present invention may be formed in the presence of an organic silver salt, formed in the absence of an organic silver salt, or a mixture of both. May be good.

[Spectral sensitization]
The photosensitive silver halide grains in the present invention are preferably subjected to spectral sensitization by adsorbing a spectral sensitizing dye. As spectral sensitizing dyes, cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, styryl dyes, hemicyanine dyes, oxonol dyes, hemioxonol dyes and the like can be used. For example, JP-A-63-159841, JP-A-60-140335, JP-A-63-231437, JP-A-63-259651, JP-A-63-304242, JP-A-63-15245, U.S. Pat. Nos. 4,740,455, 4,741,966, 4,751,175, and 4,835,096 can be used. Useful sensitizing dyes used in the present invention are described in, for example, the literature described or cited in RD17643 IV-A (December 1978, p.23) and 18431X (August 1978, p.437). ing. In particular, it is preferable to use a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of the light sources of various laser imagers and scanners. For example, compounds described in JP-A Nos. 9-34078, 9-54409, and 9-80679 are preferably used.

  Useful cyanine dyes are, for example, cyanine dyes having basic nuclei such as thiazoline nucleus, oxazoline nucleus, pyrroline nucleus, pyridine nucleus, oxazole nucleus, thiazole nucleus, selenazole nucleus and imidazole nucleus. Useful merocyanine dyes are preferably acidic nuclei such as thiohydantoin nucleus, rhodanine nucleus, oxazolidinedione nucleus, thiazolinedione nucleus, barbituric acid nucleus, thiazolinone nucleus, malononitrile nucleus and pyrazolone nucleus in addition to the basic nuclei described above. Including.

  In the present invention, it is particularly preferable to use a sensitizing dye having spectral sensitivity in the infrared. Infrared spectral sensitizing dyes preferably used in the present invention are disclosed in, for example, US Pat. Nos. 4,536,473, 4,515,888, and 4,959,294. Infrared spectral sensitizing dyes.

  The infrared spectral sensitizing dye used in the present invention is particularly preferably a long-chain polymethine dye characterized in that a sulfinyl group is substituted on the benzene ring of the benzazole ring.

  The above-mentioned infrared sensitizing dyes are described in, for example, HM Hammer, The Chemistry of Heterocyclic Compounds, Vol. 18, The Cyanine Dies and Related Compounds, published by A. Weissberger ed. It can be easily synthesized by the method.

  These infrared sensitizing dyes are preferably added after the silver halide is prepared and mixed with the aliphatic carboxylic acid silver salt. Further, it is preferably added to a light-sensitive emulsion containing silver halide grains in a so-called solid dispersion state dispersed in the form of fine particles. Similarly to the heteroatom-containing compound having adsorptivity to the silver halide grains, chemical sensitization can be performed after adding and adsorbing to the silver halide grains prior to chemical sensitization. Therefore, it is possible to prevent dispersion of the chemical sensitization central core and achieve high sensitivity and low fog.

  In the present invention, the above-mentioned spectral sensitizing dyes may be used alone or in combination, and the combination of sensitizing dyes is often used for the purpose of supersensitization.

[Supersensitizer]
The emulsion containing the photosensitive silver halide and the aliphatic carboxylic acid silver salt used in the silver salt electrophotographic dry imaging material of the present invention contains a dye having no spectral sensitizing action or visible light itself together with the sensitizing dye. Although it is a substance that does not substantially absorb, a substance that exhibits a supersensitization effect may be included in the emulsion, whereby the silver halide grains may be supersensitized.

  Useful sensitizing dyes, combinations of dyes exhibiting supersensitization, and substances exhibiting supersensitization are described in RD17643 (issued in December, 1978), page 23, Section J, or Japanese Patent Publication No. 9-25500, As described in JP-A-59-19032, 59-192242, JP-A-5-341432, and the like, as the supersensitizer, a heteroaromatic mercapto compound or a mercapto derivative compound represented by the following can be used. preferable.

Ar-SM ₁
In the formula, M ₁ is a hydrogen atom or an alkali metal atom, and Ar is an aromatic ring or condensed aromatic ring having one or more nitrogen, sulfur, oxygen, selenium, or tellurium atoms. Preferred heteroaromatic rings are benzimidazole, naphthimidazole, benzthiazole, naphthothiazole, benzoxazole, naphthoxazole, benzselenazole, benztelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine, Purine, quinoline, or quinazoline. However, other heteroaromatic rings may be included.

  In addition, a mercapto derivative compound which substantially produces the above mercapto compound when contained in a dispersion of an aliphatic carboxylic acid silver salt and / or a silver halide grain emulsion is also included. In particular, mercapto derivative compounds represented below are preferred examples.

Ar-SS-Ar
Ar in the formula has the same meaning as in the case of the mercapto compound represented above.

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

  In addition to the supersensitizer described above, compounds represented by the general formula (1) and macrocycles described in paragraph No. 0012 of JP-A No. 2001-215562 can be used as the supersensitizer.

  The macrocyclic compound described above is preferably a 9-membered or higher macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom, and a selenium atom as a hetero atom. Furthermore, a 12-24 membered ring is preferable, and a 15-21 membered ring is still more preferable.

  As a representative compound, a compound known as crown ether was synthesized by Pederson in 1967, and has been synthesized many times since its unique quality was reported.

  These compounds are C.I. J. et al. Pederson, Journal of American Chemical Society vol. 86 (2495), 7017-7036 (1967), G. Pedalson, Journal of American Chemical Society vol. W. Gokel, S.M. H, Korzenowski, “Macrocyclic polyethr synthesis”, Springer-Vergal, (1982), Oda, Shono, Tabushi, “Chemistry of Crown Ether” Chemistry Dojin (1978), Tafushi, “Host-Guest” Kyoritsu Shuppan (1979), Sasaki Koga "Synthetic Organic Chemistry" Vol 45 (6), 571-582 (1987).

  The supersensitizer that can be used in the present invention is preferably used in the range of 0.001 to 1.0 mol per mol of silver in the emulsion layer containing an organic silver salt and silver halide grains. Particularly preferred is an amount in the range of 0.01 to 0.5 moles per mole of silver.

〔binder〕
The silver salt photothermographic dry imaging material of the present invention contains a copolymer obtained by suspension polymerization of a monomer composition containing a fluorine-containing acrylate or a fluorine-containing methacrylate in an aqueous medium, and contains a binder. To do. Suitable binders are transparent or translucent and are generally colorless, natural polymer synthetic resins, polymers and copolymers, and other film-forming media such as: gelatin, gum arabic, poly (vinyl alcohol), hydroxyethyl cellulose, cellulose acetate , Cellulose acetate butyrate, poly (vinyl pyrrolidone), casein, starch, poly (acrylic acid), poly (methyl methacrylic acid), poly (vinyl chloride), poly (methacrylic acid), copoly (styrene-maleic anhydride), Copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins , Poly Vinylidene chloride), poly (epoxides), poly (carbonates), poly (vinyl acetate), cellulose esters, and polyamides. It may be hydrophilic or non-hydrophilic.

  Preferred binders for the photosensitive layer of the silver salt photothermographic dry imaging material of the present invention are polyvinyl acetals, and a particularly preferred binder is polyvinyl butyral. For non-photosensitive layers such as overcoat layers and undercoat layers, especially protective layers and backcoat layers, cellulose esters which are polymers with higher softening temperatures, especially polymers such as triacetyl cellulose and cellulose acetate butyrate preferable. In addition, as needed, said binder can be used in combination of 2 or more type.

Such a binder is used in an effective range to function as a binder. The effective range can be easily determined by one skilled in the art. For example, as an index for holding at least an aliphatic carboxylic acid silver salt in the photosensitive layer, the ratio of the binder to the aliphatic carboxylic acid silver salt is 15: 1 to 1: 2, particularly 8: 1 to 1: 1. A range is preferred. That is, it is preferable amount of the binder in the photosensitive layer is a 1.5~6g / m ^2. More preferably, it is 1.7-5 g / m < ² >. If it is less than 1.5 g / m ² , the density of the unexposed area is significantly increased and may not be used.

  The present invention is characterized in that the heat transition temperature after development at a temperature of 100 ° C. or higher is 46 ° C. or higher and 200 ° C. or lower. The heat transition temperature referred to in the present invention is a value indicated by the VICAT softening point or ring-and-ball method, and is a differential scanning calorimeter (DSC), for example, EXSTAR 6000 (manufactured by Seiko Electronics), DSC220C (manufactured by Seiko Electronics Industry) DSC-7 (manufactured by Perkin Elmer Co., Ltd.) or the like is used to indicate the endothermic peak when the thermally developed photosensitive layer is isolated and measured. In general, polymer compounds have a glass transition point Tg, but in silver salt photothermographic dry imaging materials, a large endothermic peak appears below the Tg value of the binder resin used in the photosensitive layer. To do. As a result of diligent investigation focusing on this thermal transition point temperature, by setting the thermal transition point temperature to 46 ° C. or higher and 200 ° C. or lower, not only the fastness of the formed coating film is increased, but also the sensitivity, maximum The photographic performance such as density and image storability is greatly improved.

  The glass transition temperature (Tg) was obtained by the method described in “Polymer Handbook” pages III-139 to III-179 (1966, Wiley and Sun, Inc.) by Brandrup et al. Tg in the case of a polymer resin is obtained by the following formula.

Tg (copolymer) (° C.) = V1Tg1 + v2Tg2 +++ vnTgn
In the formula, v1, v2, and vn represent mass fractions of monomers in the copolymer, and Tg1, Tg2, and Tgn are Tg (° C.) of a single polymer obtained from each monomer in the copolymer. ). The accuracy of Tg calculated according to the above equation is ± 5 ° C.

  In the silver salt photothermographic dry imaging material of the present invention, an aliphatic carboxylic acid silver salt and the copolymer of the present invention can be used on the support, and a conventionally known polymer compound can be used. The Tg is 70 to 105 ° C., the number average molecular weight is 1,000 to 1,000,000, preferably 10,000 to 500,000, and the degree of polymerization is about 50 to 1,000. Examples of such include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic ester, styrene, butadiene, ethylene, vinyl butyral, vinyl acetal, There are compounds made of a polymer or copolymer containing an ethylenically unsaturated monomer such as vinyl ether as a constituent unit, polyurethane resins, and various rubber resins.

  Moreover, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, formaldehyde resin, silicone resin, epoxy-polyamide resin, polyester resin, and the like can be given. These resins are described in detail in “Plastic Handbook” issued by Asakura Shoten. There is no restriction | limiting in particular in these high molecular compounds, A homopolymer or a copolymer may be sufficient if the glass transition temperature (Tg) of the induced | guided | derived polymer exists in the range of 70-105 degreeC.

  Polymers or copolymers containing such ethylenically unsaturated monomers as structural units include acrylic acid alkyl esters, acrylic acid aryl esters, methacrylic acid alkyl esters, methacrylic acid aryl esters, alkyl cyanoacrylates. Ester, cyanoacrylic acid aryl ester and the like, and the alkyl group and aryl group thereof may or may not be substituted. Specifically, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, hexyl, cyclohexyl, benzyl, chlorobenzyl, octyl, stearyl, sulfopropyl, N-ethyl-phenylaminoethyl, 2- (3-phenylpropyloxy) ethyl , Dimethyl Minophenoxyethyl, furfuryl, tetrahydrofurfuryl, phenyl, cresyl, naphthyl, 2-hydroxyethyl, 4-hydroxybutyl, triethylene glycol, dipropylene glycol, 2-methoxyethyl, 3-methoxybutyl, 2-acetoxyethyl, 2 -Acetoacetoxyethyl, 2-ethoxyethyl, 2-iso-propoxyethyl, 2-butoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- (2-ethoxyethoxy) ethyl, 2- (2-butoxyethoxy) Examples thereof include ethyl, 2-diphenylphosphorylethyl, ω-methoxypolyethylene glycol (addition mole number n = 6), allyl, dimethylaminoethylmethyl chloride salt and the like.

  In addition, the following monomers can be used. Specific examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl chloroacetate, vinyl methoxyacetate, vinyl phenyl acetate, vinyl benzoate, vinyl salicylate. N-substituted acrylamides, N-substituted methacrylamides and acrylamides, methacrylamides: N-substituents include methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl, benzyl, hydroxymethyl, methoxyethyl, dimethyl Aminoethyl, phenyl, dimethyl, diethyl, β-cyanoethyl, N- (2-acetoacetoxyethyl), diacetone and the like; olefins: for example, dicyclopentadiene, ethylene, propylene, 1- Ten, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene, etc .; styrenes: for example, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, tert-butylstyrene , Chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl benzoic acid methyl ester, etc .; vinyl ethers: for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethyl vinyl ether N-substituted maleimides: As N-substituent, methyl, ethyl, propyl, butyl, tert-butyl, cyclohexyl , Benzyl, n-dodecyl, phenyl, 2-methylphenyl, 2,6-diethylphenyl, 2-chlorophenyl, etc .; others include butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate , Diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, dibutyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, glycidyl acrylate, glycidyl methacrylate, N-vinyl oxazolidone, N -Vinylpyrrolidone, acrylonitrile, methacrylonitrile, methylenemalonnitrile, vinylidene chloride and the like can be mentioned.

  Among these, particularly preferred examples include methacrylic acid alkyl esters, methacrylic acid aryl esters, styrenes, and the like. Among such polymer compounds, it is preferable to use a polymer compound having an acetal group. The polymer compound having an acetal group is preferable because it is excellent in compatibility with the aliphatic carboxylic acid to be produced and has a great effect of preventing the film from being softened.

[Crosslinking agent]
In the present invention, it is known that the use of a crosslinking agent with respect to the binder improves the film formation and reduces development unevenness. However, it prevents fogging during storage and produces printed silver after development. There is also an inhibitory effect.

  Examples of the crosslinking agent used in the present invention include various crosslinking agents conventionally used for silver halide photographic light-sensitive materials, such as aldehyde-based, epoxy-based, and ethyleneimine-based compounds described in JP-A-50-96216. , Vinyl sulfone type, sulfonic acid ester type, acryloyl type, carbodiimide type, isocyanate type, silane compound type cross-linking agent or acid anhydride can be used, but is preferably an isocyanate type compound, silane compound, epoxy compound or acid anhydride. is there.

  In the present invention, the crosslinking agent can be added to any layer on the photosensitive layer side of the support, such as a photosensitive layer, a surface protective layer, an intermediate layer, an antihalation layer, an undercoat layer, and one or two of these layers. It can be added to more than the layer.

(Matting agent)
In the present invention, the surface layer of the silver salt photothermographic dry imaging material (even when the photosensitive layer side or the non-photosensitive layer is provided on the opposite side of the photosensitive layer with the support sandwiched) is handled before development or thermal development. It is preferable to contain a matting agent in order to prevent the subsequent image from being damaged, and it is preferable to contain 0.1 to 30% by mass with respect to the binder.

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

  The matting agent 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.

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

Variation coefficient of particle size distribution = (standard deviation of particle size / average value of particle size) × 100
The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed and applied in advance in the coating solution, or a method in which the matting agent is sprayed after the coating solution is applied and before drying is completed. May be. When a plurality of types of matting agents are added, both methods may be used in combination.

[Support / Auxiliary layer / Others]
Examples of the support material used in the silver salt photothermographic dry imaging material of the present invention include various polymer materials, glass, wool cloth, cotton cloth, paper, metal (for example, aluminum), etc. In terms of handling, a material that can be processed into a flexible sheet or roll is suitable. Therefore, as a support in the silver salt photothermographic dry imaging material of the present invention, a plastic film (for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, cellulose triacetate film, polycarbonate film, etc. In the present invention, a biaxially stretched polyethylene terephthalate film is particularly preferable. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

  In the present invention, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layers in order to improve the chargeability. These may be contained in any layer, but are preferably contained in the undercoat layer, the backing layer, the layer between the photosensitive layer and the undercoat, and the like. In the present invention, the conductive compounds described in US Pat. No. 5,244,773, columns 14 to 20 are preferably used.

  The silver salt photothermographic dry imaging material of the present invention has at least one photosensitive layer on a support. A non-photosensitive layer including at least one protective layer is formed on the photosensitive layer. For example, a protective layer is provided on the photosensitive layer, and a back coat layer is provided on the opposite side of the support to prevent sticking between the photosensitive materials or in the photosensitive material roll. Preferably it is provided. Binders used in these protective layers and backcoat layers have a glass transition point higher than that of the photosensitive layer, and polymers such as scratches and deformations, such as cellulose acetate and cellulose acetate butyrate, are the above-mentioned binders. It is chosen from among them. In order to adjust the gradation, two or more photosensitive layers may be provided on one side of the support or one or more layers on both sides of the support.

  In the silver salt photothermographic dry imaging material of the present invention, a filter layer is formed on the same side as or opposite to the photosensitive layer in order to control the amount of light transmitted through the photosensitive layer or the wavelength distribution, or a dye is formed on the photosensitive layer. Or it is preferable to contain a pigment.

  As the dye used, known compounds that absorb light in various wavelength regions can be used depending on the color sensitivity of the photosensitive material.

  For example, when the silver salt photothermographic dry imaging material of the present invention is used as an image recording material by infrared light, it has a squarylium dye having a thiopyrylium nucleus and a pyrylium nucleus as disclosed in JP-A-2001-83655. Preference is given to using squarylium dyes, thiopyrylium croconium dyes similar to squarylium dyes, or pyrylium croconium dyes.

  The compound having a squarylium nucleus is a compound having 1-cyclobutene-2-hydroxy-4-one in the molecular structure, and the compound having a croconium nucleus is 1-cyclopentene-2-hydroxy- in the molecular structure. It is a compound having 4,5-dione. Here, the hydroxyl group may be dissociated. Hereinafter, in the present specification, these pigments are collectively referred to as squarylium dyes for convenience.

  As the dye, a compound described in JP-A-8-201959 is also preferable.

  The silver salt photothermographic dry imaging material of the present invention is formed by forming a coating solution in which the above-described constituent layer materials are dissolved or dispersed in a solvent, and applying a plurality of coating solutions simultaneously, followed by heat treatment. It is preferable. Here, "multiple simultaneous multi-layer coating" means that a coating solution for each constituent layer (for example, a photosensitive layer and a protective layer) is prepared, and when coating this onto a support, each layer is individually coated and dried repeatedly. In other words, it means that each constituent layer can be formed in such a state that the multilayer coating and drying can be performed simultaneously. That is, the upper layer is provided before the remaining amount of the total solvent in the lower layer becomes 70% by mass or less.

  There are no particular restrictions on the method of applying multiple layers of each constituent layer simultaneously, and for example, a known method such as a bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, or extrusion coating method may be used. Can do. Of these, a pre-weighing type coating method called an extrusion coating method is more preferable. Since the extrusion coating method does not volatilize on the slide surface unlike the slide coating method, it is suitable for precision coating and organic solvent coating. Although this coating method has been described on the side having the photosensitive layer, the same applies to the case of coating with undercoating when providing the backcoat layer.

[Exposure method]
In the present invention, the exposure is preferably performed by laser scanning exposure, but various methods can be adopted as the exposure method. For example, as a first preferred method, there is a method using a laser scanning exposure machine in which the angle formed by the exposure surface of the photosensitive material and the scanning laser beam is not substantially perpendicular.

  Here, “substantially not perpendicular” means that the angle closest to the vertical during laser scanning is preferably 55 degrees or more and 88 degrees or less, more preferably 60 degrees or more and 86 degrees or less, and further Preferably it is 65 degrees or more and 84 degrees or less, Most preferably, it is 70 degrees or more and 82 degrees or less.

  The beam spot diameter on the exposure surface of the photosensitive material when the laser beam is scanned on the photosensitive material is preferably 200 μm or less, more preferably 100 μm or less. This is preferable in that a smaller spot diameter can reduce the angle of deviation of the laser incident angle from the vertical. The lower limit of the beam spot diameter is 10 μm. By performing such laser scanning exposure, it is possible to reduce image quality deterioration related to reflected light such as generation of interference fringe-like unevenness.

  As a second method, the exposure in the present invention is also preferably performed using a laser scanning exposure machine that emits a scanning laser beam that is a vertical multi. Compared with a single longitudinal mode scanning laser beam, image quality degradation such as generation of interference fringe-like unevenness is reduced.

  In order to make it vertically multi-ply, methods such as using return light by multiplexing and applying high-frequency superposition are preferable. The vertical multi means that the exposure wavelength is not single, and the distribution of the exposure wavelength is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

In the image recording methods of the first and second aspects described above, as a laser used for scanning exposure, generally well-known solid lasers such as ruby laser, YAG laser, and glass laser; HeNe laser, Ar ion Gas laser such as laser, Kr ion laser, CO ₂ laser, CO laser, HeCd laser, N ₂ laser, excimer laser; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb laser, etc. Semiconductor lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner, but among these, semiconductor lasers with a wavelength of 600 to 1200 nm are used due to problems of maintenance and the size of the light source. Masui. In addition, in a laser used in a laser imager or a laser image setter, the beam spot diameter on the material exposure surface when scanned with a silver salt photothermographic dry imaging material is generally 5 to 75 μm as a minor axis diameter, The major axis diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photosensitive material depending on the sensitivity and laser power at the laser oscillation wavelength unique to the silver salt photothermographic dry imaging material.

[Heat development method]
In the present invention, the development conditions vary depending on the equipment, equipment, or means used, but typically involve heating the imagewise exposed silver salt photothermographic dry imaging material at a suitable high temperature. . The latent image obtained after exposure is obtained by heating the silver salt photothermographic dry imaging material at a moderately high temperature (eg, about 100-200 ° C.) for a sufficient time (generally about 1 second to about 2 minutes). It can be developed. When the heating temperature is 100 ° C. or lower, sufficient image density cannot be obtained in a short time, and when the heating temperature is 200 ° C. or higher, the binder melts, and not only the image itself, such as transfer to a roller, but also adversely affects the transportability and the developing machine. Effect. By heating, a silver image is generated by a redox reaction between the aliphatic carboxylic acid silver salt (which functions as an oxidizing agent) and the reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside.

  The heating device, apparatus, and means may be a heating means typical as a heat generator using a hot plate, iron, hot roller, carbon, white titanium, or the like. More preferably, in the silver salt photothermographic dry imaging material provided with the protective layer of the present invention, the surface on the side having the protective layer is brought into contact with the heating means, and the heat treatment is performed for uniform heating and thermal efficiency. From the viewpoint of workability and the like, it is preferable that the surface is conveyed while being brought into contact with a heat roller, heated and developed.

  In the exposure of the silver salt photothermographic dry imaging material of the present invention, it is desirable to use an appropriate light source for the color sensitivity imparted to the photosensitive material. For example, if the photosensitive material is sensitive to infrared light, it can be applied to any light source as long as it is in the infrared light range, but the laser power is high and the photosensitive material can be transparent. In view of the above, an infrared semiconductor laser (780 nm, 820 nm) is more preferably used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
-Viscosity control of coating solution for image forming layer-
<Preparation of underdrawn support>
One surface of a blue-colored polyethylene terephthalate film base (thickness: 175 μm) having a density of 0.170 was subjected to a corona discharge treatment of 0.5 kV · A · min / m ² , and then the following image forming layer side The undercoat layer “a” was applied using the lower quoted coating solution A so that the dry film thickness was 0.2 μm. Further, after the corona discharge treatment of 0.5 kV · A · min / m ² was similarly applied to the other surface, the following undercoat coating solution B on the backing layer side was used, and the undercoat layer b was The coating was applied so that the dry film thickness was 0.1 μm. Thereafter, heat treatment was performed at 130 ° C. for 15 minutes in a heat treatment oven having a film conveying device composed of a plurality of roll groups, and a subbing support was produced.

(Image forming layer side lower reference coating solution A)
74 g of copolymer latex solution (solid content 30%) of 30% by mass of n-butyl acrylate, 20% by mass of t-butyl acrylate, 25% by mass of styrene and 25% by mass of 2-hydroxyethyl acrylate, surfactant (UL-1 ) 0.1g and methylcellulose 0.5g were mixed. Further, 1.3 g of silica particles (Syloid 350, manufactured by Fuji Silysia) was added to 100 g of water, and the dispersion was subjected to a dispersion treatment for 30 minutes with an ultrasonic dispersing machine (manufactured by ALEX Corporation, Ultrasonic Generator, frequency 25 kHz, 600 W). Was finally made up to 1000 ml with water, and this was used as the undercoat coating solution A.

(Preparation of colloidal tin oxide dispersion)
A homogeneous solution was prepared by dissolving 65 g of stannic chloride hydrate in 2000 ml of a water / ethanol mixed solution. Subsequently, this was boiled and the coprecipitate was obtained. The generated precipitate was taken out by decantation and washed several times with distilled water. Silver nitrate is dropped into distilled water from which the precipitate has been washed, and after confirming that there is no reaction of chlorine ions, distilled water is added to the washed precipitate to make a total volume of 2000 ml. Furthermore, 40 ml of 30% aqueous ammonia was added, the aqueous solution was heated, and concentrated to a volume of 470 ml to prepare a colloidal tin oxide dispersion.

(Backing layer side lower quoted coating solution B)
A copolymer latex liquid (solid content 30) of 37.5 g of the above colloidal tin oxide dispersion, 20% by mass of n-butyl acrylate, 30% by mass of t-butyl acrylate, 27% by mass of styrene and 28% by mass of 2-hydroxyethyl acrylate. %) 3.7 g, n-butyl acrylate 40 mass%, styrene 20 mass%, glycidyl methacrylate 40 mass% copolymer latex liquid (solid content 30%) 14.8 g and surfactant UL-1 0.1 g Were mixed and finished to 1000 ml with water to obtain an undercoat coating solution B.

<Coating liquid for backing layer>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (manufactured by Eastman Chemical, CAB381-20) and 4.5 g of polyester resin (manufactured by Boston, VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the dissolved solution, and 4.5 g of F-type activator (Surflon KH40, manufactured by Asahi Glass Co., Ltd.) and F-type activator (Dainippon) were dissolved in 43.2 g of methanol. 2.3 g (MegaFag F120K, manufactured by Ink Co., Ltd.) was added and stirred sufficiently until dissolved. Finally, 75 g of silica (manufactured by WR Grace, Syloid 64X6000) dispersed in methyl ethyl ketone at a concentration of 1% by mass with a dissolver type homogenizer was added and stirred to obtain a backing layer coating solution.

  The backing layer coating solution was applied and dried by an extrusion coater on the backing layer side undercoat of the undercoated support so that the dry film thickness was 3.5 μm. It dried for 5 minutes using the drying air with a drying temperature of 100 degreeC, and dew point temperature of 10 degreeC.

<Preparation of photosensitive silver halide emulsion>
Solution (A1)
Phenylcarbamoylated gelatin 88.3g
Compound (K) (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water.
Solution (B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
Solution (C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finish to 660 ml with water.
Solution (D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
Osmium chloride (1% solution) 0.93ml
Finish to 1982 ml with water.
Solution (E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount solution (F1)
Potassium hydroxide 0.71g
Finish to 20 ml with water.
Solution (G1)
56% acetic acid aqueous solution 18.0 ml
Solution (H1)
Anhydrous sodium carbonate 1.72 g
Finish to 151 ml with water.

Compound (K):
_{HO (CH 2 CH 2 O)} n (CH (CH 3) CH 2 O) 17 (CH 2 CH 2 O) m H
(M + n = 5-7)
Using the mixing stirrer shown in Japanese Patent Publication Nos. 58-58288 and 58-58289, ¼ amount of the solution (B1) and the whole amount of the solution (C1) were added to the solution (A1) at a temperature of 40 ° C., pAg 8.09. While being controlled, nucleation was carried out by adding 4 minutes 45 seconds by the simultaneous mixing method. After 1 minute, the entire amount of the solution (F1) was added, followed by 20 ml of a 5% aqueous solution of 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene. During this time, the pAg was adjusted as appropriate using the aqueous solution (E1). After 6 minutes, 3/4 amount of the solution (B1) and the whole amount of the solution (D1) were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling the temperature at 25 ° C. and pAg 8.09. After stirring for 5 minutes, the entire amount of the solution (G1) was added to precipitate the silver halide emulsion. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 L of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 L of water was further added, and after stirring, the silver halide emulsion was allowed to settle. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution (H1) 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 mole of silver to obtain an emulsion.

  This emulsion was monodisperse cubic silver iodobromide grains having an average grain size of 0.034 μm, a grain size variation coefficient of 14%, and a [100] face ratio of 92%.

  Next, 240 ml of triphenylphosphine sulfide (0.5% methanol solution) was added to the above emulsion, and a chloroauric acid sensitizer equivalent to 1/20 mol of this sensitizer was added, followed by stirring at 55 ° C. for 120 minutes. Then, chemical sensitization was performed. This is a photosensitive silver halide emulsion.

<Preparation of powdered aliphatic carboxylic acid silver salt>
130.8 g of behenic acid, 67.7 g of arachidic acid, 43.6 g of stearic acid, and 2.3 g of palmitic acid were dissolved in 4720 ml of pure water at 80 ° C. Next, 540.2 ml of a 1.5 M / L sodium hydroxide aqueous solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a fatty acid sodium solution. While maintaining the temperature of the fatty acid sodium solution at 55 ° C., 45.3 g of the above photosensitive silver halide emulsion and 450 ml of pure water were added and stirred for 5 minutes.

  Next, 702.6 ml of 1 M / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an aliphatic carboxylic acid silver salt dispersion. Thereafter, the obtained fatty carboxylic acid silver salt dispersion is transferred to a water washing container, deionized water is added and stirred, and then allowed to stand to float and separate the aliphatic carboxylic acid silver salt dispersion, and the lower water-soluble salts are removed. Removed. Thereafter, washing with deionized water and drainage were repeated until the electrical conductivity of the drainage reached 50 μS / cm, and centrifugal dehydration was carried out. Using a drier (manufactured by Seishin Enterprise Co., Ltd.), a powdered aliphatic carboxylic acid silver salt was obtained by drying until the water content became 0.1% under the operating conditions of nitrogen gas atmosphere and dryer inlet hot air temperature. An infrared moisture meter was used to measure the water content of the aliphatic carboxylic acid silver salt composition.

<Preparation of preliminary dispersion>
14.57 g of polyvinyl butyral resin is dissolved in 1457 g of methyl ethyl ketone, and 500 g of powdered aliphatic carboxylic acid silver salt is gradually added and thoroughly mixed while stirring with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN. A preliminary dispersion was prepared.

<Preparation of photosensitive emulsion dispersion>
Media type disperser DISPERMAT SL- filled with 80% of the internal volume of 0.5 mm zirconia beads (manufactured by Treceram Toray) so that the residence time in the mill is 1.5 minutes using a pump. A photosensitive emulsion dispersion was prepared by supplying to a C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<Preparation of additive solution A>
The following macrocyclic compound Sa-19 containing 1.0 g of a heteroatom and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare an additive solution A.

<Preparation of infrared sensitizing dye liquid A>
19.2 mg of the following infrared sensitizing dye 1-3, 1.488 g 2-chloro-benzoic acid, 2.7779 g stabilizer 2 and 365 mg 5-methyl-2-mercaptobenzimidazole Infrared sensitizing dye solution A was prepared by dissolving in MEK in the dark.

<Preparation of additive liquid a1>
As a developer, A-8 was dissolved in 14.0 g and 1.54 g of 4-methylphthalic acid, and 0.48 g of the infrared dye 1 was dissolved in 110 g of MEK to obtain an additive solution a1.

<Preparation of additive liquid b>
3.43 g of phthalazine was dissolved in 40.9 g of MEK to obtain additive solution b.

<Preparation of additive liquid c>
3.56 g of antifoggant 2 and 0.25 g of sodium p-toluenethiosulfonate were dissolved in 40.9 g of MEK to obtain additive liquid c.

<Preparation of image forming layer coating solution 1>
In an inert gas atmosphere (nitrogen 97%), the photosensitive emulsion dispersion (50 g) and 15.1 g of MEK were kept at 21 ° C. with stirring, and 390 μl of antifoggant 1 (10% methanol solution) was added. Stir for hours. Next, a methanol solution of iridium chloride was added so as to be 1.0 × 10 ⁻⁵ mol per mol of silver halide, and 494 μl of calcium bromide (10% methanol solution) was further added, followed by stirring for 30 minutes. Subsequently, 0.21 g of the additive solution A and 1.32 g of the infrared sensitizing dye solution A were added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While keeping the temperature at 13 ° C., 13.3 g of polyvinyl acetal resin as a binder resin was added and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4 mass% MEK solution) was added and stirred for 15 minutes. . While continuing to stir, 12.43 g of additive liquid a1, 1.6 ml of Desmodur N3300 / Moby aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b, 10.0 g of additive liquid c By sequentially adding and stirring, an image forming layer coating solution 1 was obtained.

<Preparation of matting agent dispersion>
Cellulose acetate butyrate (Eastman Chemical Co., 7.5 g CAB171-15) was dissolved in MEK 42.5 g, and calcium carbonate (Speciality Minerals Co., Super-Pflex 200) 5 g was added, and a dissolver type homogenizer was added. Was dispersed at 8000 rpm for 30 minutes to prepare a matting agent dispersion.

<Preparation of protective layer coating solution>
While stirring 865 g of MEK (methyl ethyl ketone), 96.0 g of cellulose acetate butyrate (manufactured by Eastman Chemical, CAB171-15), 4.5 g of polymethylmethacrylic acid (Rohm & Haas, Paraloid A-21), 1.5 g of vinylsulfone compound (VSC), 1.0 g of benztriazole, and 1.0 g of F-based activator (Asahi Glass Co., Surflon KH40) were added and dissolved. Next, 30 g of the matting agent dispersion was added and stirred to prepare a protective layer coating solution 1.

  The structure of the additive used for each additive solution and coating solution is shown below.

<Preparation of silver salt photothermographic dry imaging material sample 101>
The image forming layer coating solution 1 and the protective layer coating solution 1 are simultaneously applied on the underdrawn support using a known extrusion coater, and then a drying temperature of 75 ° C. and a dew point temperature of 10 are applied. Drying was performed for 10 minutes using a drying air at 0 ° C. to obtain a silver salt photothermographic dry imaging material sample 101. The coating was performed such that the silver in the image forming layer was 1 × 10 ⁻⁴ g / m ³ per unit volume and the protective layer was 2.5 μm in dry film thickness.

<Preparation of silver salt photothermographic dry imaging material samples 102-106>
In the image forming layer coating solution 1, except that the polyvinyl acetal amount, MEK amount, the type and amount of the copolymer of the present invention added when preparing the image forming layer coating solution were changed as shown in Table 1. Similarly, the image forming layer coating solutions 2 to 6 were prepared, and silver salt photothermographic dry imaging material samples 102 to 106 were prepared under the same coating and drying conditions as the silver salt photothermographic dry imaging material sample 101, respectively.

<Exposure and development processing>
From the emulsion surface side of each prepared sample, exposure by laser scanning was given by an exposure machine using an exposure source of a semiconductor laser that was converted into a longitudinal multimode having a wavelength of 800 to 820 nm by high frequency superposition. At this time, an image was formed by setting the angle of the exposure surface of the sample and the exposure laser beam to 75 degrees. Note that an image with less unevenness and unexpectedly good sharpness or the like was obtained compared to the case where the angle was 90 degrees.

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

[Evaluation]
<Viscosity measurement>
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds with respect to the image forming layer coating solutions 1 to 6 using a rheological stress RS1 manufactured by Hake, 5 minutes strain 0.4, frequency 2 Hz When the vibration was applied, the viscosity immediately after the start of vibration was η _A , and the viscosity 5 minutes after the start of vibration was η _B.

The results are shown in Table 1. Η _A and η _B of the image forming layer coating liquids 1 to 6 are sample Nos. It wrote in the column of 101-106.

<Evaluation of sensitivity>
The obtained image was evaluated with a densitometer. The measurement results were evaluated by sensitivity (the reciprocal of the ratio of the exposure amount giving a density 1.0 higher than that of the unexposed portion), and expressed as a relative value when the sample 101 was 100.

<Evaluation of applicability>
The state of occurrence of streak unevenness immediately after the coating solution was applied to the support was observed and evaluated according to the following criteria. The results are shown in Table 1.

5 No unevenness 4 Slight unevenness, close to no unevenness 3 Partially uneven 2 Not quite the entire surface, but fairly uneven 1 The surface is uneven (uniformity in the surface)
A solid image at an average optical density of 1.0 was visually evaluated according to the following criteria, and the results are shown in Table 1.

5 Density unevenness is inconspicuous 4 Although there is slight density unevenness, it is close to inconspicuous density unevenness 3 Density unevenness is slightly conspicuous 2 Although it is not until the density unevenness is very conspicuous 1 A little density unevenness is conspicuous

  Sample No. In all of 101 to 106, the relative sensitivity was 100.

  As can be seen from Table 1, the sample of the present invention has no sensitivity reduction, good coatability, and excellent in-plane uniformity of the processed image.

Example 2
-Viscosity control of coating liquid for protective layer-
In the protective layer coating solution 1 in Example 1, the protective layer coating solutions 2 to 5 were similarly prepared except that the amount of cellulose acetate butyrate, the amount of MEK, the type and amount of the alkyd resin were changed as shown in Table 2. Obtained were silver salt photothermographic dry imaging material samples 202 to 205, respectively.

<Viscosity measurement>
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds for the protective layer coating solutions 1 to 5 using Rheo Stress RS1 manufactured by Hake, 5 minutes strain 0.4, frequency 2 Hz When vibration was applied, the viscosity immediately after the start of vibration was η _C , and the viscosity 5 minutes after the start of vibration was η _D. The results are shown in Table 2. Η _C and η _D of the protective layer coating liquids 1 to 5 are the sample Nos. 101, 202-205.

<Exposure and development processing>
Exposure and development were performed in the same manner as in Example 1.

<Evaluation of sensitivity>
The sensitivity was evaluated in the same manner as in Example 1.

<Evaluation of applicability>
The coatability was evaluated in the same manner as in Example 1, and the results are shown in Table 2.

(In-plane uniformity)
In-plane uniformity was evaluated in the same manner as in Example 1, and the results are shown in Table 2.

  Sample No. Relative sensitivity was 100 in all of 202-205.

  As can be seen from Table 2, the sample of the present invention has no sensitivity reduction, good coatability, and excellent in-plane uniformity of the processed image.

Claims (2)

A silver salt photothermographic dry imaging material having at least one image forming layer and a protective layer in this order on at least one surface of a support, wherein at least one layer of the image forming layer contains a fluorine-containing acrylate or Applying and drying an image forming layer coating solution containing a copolymer obtained by suspension polymerization of a monomer composition containing a fluorine-containing methacrylate in an aqueous medium, and the image forming layer satisfies the following viscosity conditions A silver salt photothermographic dry imaging material obtained by
(Viscosity condition)
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, when applying vibration with strain of 0.4 and frequency of 2 Hz for 5 minutes, the viscosity immediately after the start of vibration is η _A , and vibration is started. When the viscosity after 5 minutes is η _B , 2.00> η _B / η _A > 1.20. A silver salt photothermographic dry imaging material having at least one image forming layer and a protective layer in this order on at least one surface of a support, wherein at least one layer of the protective layer contains fluorine-containing acrylate or fluorine. A monomer composition containing a methacrylate that contains a copolymer obtained by suspension polymerization in an aqueous medium, and the protective layer is obtained by applying and drying a protective layer coating solution that satisfies the following viscosity conditions: A silver salt photothermographic dry imaging material characterized by the above.
(Viscosity condition)
Immediately after applying shear at a shear rate of 1000 (1 / s) at 23 ° C. for 30 seconds, when applying vibration with a strain of 0.4 and a frequency of 2 Hz for 5 minutes, the viscosity immediately after the start of vibration is η _C , and vibration is started. When the viscosity after 5 minutes is η _D , 2.00> η _D / η _C > 1.09.