JP2007079237A - Silver salt photothermographic dry imaging material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver salt photothermographic dry imaging material excellent in image preservability and raw stock preservability, having low fog and high maximum density, and excellent in silver tone and density variation due to humidity change, even when rapidly heat-developed with a small laser imager, and an image forming method. <P>SOLUTION: The silver salt photothermographic dry imaging material has on a support a photosensitive layer containing an organic silver salt, silver halide grains, a binder and a reducing agent, contains a bisphenol compound having a specific structure as the reducing agent, and contains a polymer obtained by copolymerizing 10-70 mass% of a monomer represented by the formula (M): CH<SB>2</SB>=CR<SB>01</SB>-CR<SB>02</SB>=CH<SB>2</SB>as the binder in the photosensitive layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a silver salt photothermographic dry imaging material (hereinafter referred to as a photothermographic dry imaging material, a photothermographic material, a photothermographic material, simply containing an organic silver salt, silver halide grains, a binder and a reducing agent on a support. The present invention also relates to an image forming method.

  Conventionally, in the fields of medical treatment and printing plate making, waste liquid from wet processing of image forming materials has been a problem in terms of workability. In recent years, reduction of waste processing liquid has been strongly desired from the viewpoint of environmental conservation and space saving. ing. Therefore, silver salt photothermographic dry imaging materials capable of forming an image only by applying heat have been put into practical use and are rapidly spreading in the above fields.

  Photothermographic dry imaging materials themselves have already been proposed for a long time, and are described, for example, in US Pat. Nos. 3,152,904 and 3,457,075.

  This silver salt photothermographic dry imaging material is usually processed by a heat development processing apparatus called a laser imager which forms an image by applying stable heat to the material. As described above, with the rapid spread in recent years, a large amount of this laser imager has been supplied to the market. In recent years, there has been a demand for a compact laser imager and rapid processing.

  For this purpose, it is essential to improve the characteristics of the photothermographic dry imaging material. In order to obtain a sufficient photographic image density even if rapid processing is performed, silver halide grains having a small average grain size as disclosed in JP-A Nos. 11-295844 and 11-352627 are disclosed. To increase the covering power by increasing the number of coloring points, using a highly active reducing agent having a secondary or tertiary alkyl group as disclosed in JP-A-2001-209145, hydrazine compounds and vinyl compounds It is effective to use a development accelerator such as a phenol derivative or a naphthol derivative (see Patent Documents 1 and 2). However, when a development accelerator is used, there is a problem that image storability and raw storability deteriorate.

  On the other hand, a technique using an isoprene-based binder has been disclosed for the purpose of improving image storage stability and processing brittleness (see Patent Document 3). However, when an isoprene-based binder is used, there is a problem that raw storage stability deteriorates, and an improvement has been desired (see Patent Document 4).

As a response from the apparatus side for downsizing and rapid processing of the laser imager, a technology for shortening the distance of the cooling unit in order to reduce the size of the laser imager (for example, refer to Patent Document 5), transport at 23 mm / second or more A technique (see Patent Documents 6 and 7) that performs thermal development while performing thermal development simultaneously with exposure is disclosed.
JP 2002006443 A (Claims) Japanese Patent Laid-Open No. 2003-065558 (Claims) JP 2004-184663 A (Claims) Japanese Patent Laying-Open No. 2005-141013 (paragraph “0012”) JP 2004-004522 A (Claims) US Patent Application Publication No. 2004/0058281 (Claims) JP 2004-087563 A (Claims)

  The present invention has been made in view of the above problems, and an object of the present invention is to provide image storability and raw storability even when a silver salt photothermographic dry imaging material is rapidly thermally developed by a small laser imager. It is an object of the present invention to provide a silver salt photothermographic dry imaging material and an image forming method which are excellent in low fog, high in the maximum density, excellent in silver tone and density fluctuation accompanying humidity change.

  When isoprene-based binders are used to improve image storage stability, there is a problem that raw storage stability (storability of the film before heat development) deteriorates, and further, rapid processing was performed with a small laser imager. In this case, the density could not be sufficiently obtained, and when a development accelerator was used to obtain the density, there was a problem that the silver tone deteriorated and the density fluctuation accompanying the humidity change increased. As a result of diligent efforts to solve these problems, the present inventor has found that it is essential to include a reducing agent containing an alkyl group having a hydroxyl group as a substituent as a reducing agent contained in the photosensitive layer. The invention has been reached. Furthermore, it has been found that the object of the present invention can be achieved at a higher level by setting the dry film thickness of the photosensitive layer to 4 μm or more and 16 μm or less.

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

  (1) It has a photosensitive layer containing an organic silver salt, silver halide grains, a binder, and a reducing agent on a support, and contains a compound represented by the following general formula (RD1) as the reducing agent. A silver salt photothermographic dry imaging material comprising a polymer obtained by copolymerization of a monomer represented by the following general formula (M) as a binder for use in the photosensitive layer in an amount of 10% by mass to 70% by mass.

[Wherein, X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. At least one of R ₂ represents a secondary or tertiary alkyl group and may be the same or different. R ₃ represents an alkyl group having 1 to 20 carbon atoms in which at least one group has a hydroxyl group as a substituent, or an alkyl group having 1 to 20 carbon atoms in which a group capable of forming a hydroxyl group by being deprotected is used as a substituent. Represents a group, which may be the same or different. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
General formula (M)
CH ₂ = CR ₀₁ -CR ₀₂ = CH ₂
(In the formula, R ₀₁ and R ₀₂ are a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms. However, R ₀₁ and R ₀₂ are not simultaneously hydrogen atoms. )
(2) The silver salt photothermographic dry imaging material as described in (1) above, wherein R _{01 in the} general formula (M) is a hydrogen atom and R ₀₂ is a methyl group.

  (3) In the item (1) or (2), the polymer represented by the general formula (M) is a polymer obtained by copolymerizing an acid group-containing monomer in an amount of 1% by mass to 20% by mass. The silver salt photothermographic dry imaging material described.

(4) At least one group of R _{3 in} the general formula (RD1) is substituted with an alkyl group having 3 to 20 carbon atoms having a hydroxyl group as a substituent, or a group capable of forming a hydroxyl group by being deprotected. The silver salt photothermographic dry imaging material according to any one of (1) to (3) above, which is an alkyl group having 3 to 20 carbon atoms as a group.

  (5) The silver salt photothermographic dry imaging material according to any one of (1) to (4) above, wherein the dry thickness of the photosensitive layer is 4 μm or more and 16 μm or less.

  (6) The silver salt photothermographic dry imaging as described in any one of (1) to (5) above, wherein the maximum value of the image density after heat development is 3.8 to 5.0. material.

  (7) At least one of the constituent layers of the silver salt photothermographic dry imaging material contains a compound that develops color during thermal development to form a dye image, and the maximum absorption wavelength of the dye image is 360 nm or more and 450 nm or less. The silver salt photothermographic dry imaging material according to any one of (1) to (6), wherein:

  (8) At least one of the constituent layers of the silver salt photothermographic dry imaging material contains a compound that develops color during heat development to form a dye image, and the maximum absorption wavelength of the dye image is 600 nm to 700 nm. The silver salt photothermographic dry imaging material according to any one of (1) to (7), wherein:

  (9) The silver salt photothermographic dry imaging material as described in any one of (1) to (8) above, which comprises a compound represented by the following general formula (SF).

General formula (SF)
(R _f − (L ₁ ) _m1 −) _p − (Y) _n1 − (A) _q
(In the formula, R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, m1 and n1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, q represents an integer of 1 to 3, provided that q is 1. (M1 and n1 are not 0 at the same time.)
(10) A sheet-like silver salt photothermographic dry imaging material, wherein the silver salt photothermographic dry imaging material according to any one of (1) to (9) is in a sheet form.

  (11) An image forming method comprising conveying the sheet-like silver salt photothermographic dry imaging material according to the item (10) while heating at a conveying speed of 30 to 200 mm / sec.

  (12) A part of the sheet-like silver salt photothermographic dry imaging material that has already been exposed while a part of the sheet-like silver salt photothermographic dry imaging material described in (10) above is exposed. An image forming method, wherein development is started.

  (13) An image forming method characterized in that the sheet-like silver salt photothermographic dry imaging material described in (10) above is developed by a laser imager in which the distance between the exposed portion and the developing portion is from 0 cm to 50 cm.

  (14) An image forming method comprising thermally developing the sheet-like silver salt photothermographic dry imaging material according to the item (10) by a laser imager with a heating time of 10 seconds or less.

(15) An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to the item (10) is thermally developed with a laser imager having an installation area of 0.40 m ² or less.

  According to the present invention, even when a silver salt photothermographic dry imaging material is rapidly heat-developed by a small laser imager, it has excellent image storability and raw storability, low fog, high maximum density, and silver tone. Further, it is possible to provide a silver salt photothermographic dry imaging material and an image forming method which are excellent in density fluctuation accompanying humidity change.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  Hereinafter, the constituent elements of the present invention will be sequentially described.

(binder)
In the present invention, a polymer obtained by copolymerizing a monomer represented by the following general formula (M) at 10% by mass or more and 70% by mass or less is used as a binder of the photosensitive layer (hereinafter also referred to as an image forming layer). .

General formula (M)
CH ₂ = CR ₀₁ -CR ₀₂ = CH ₂
In the formula, R ₀₁ and R ₀₂ are a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms. However, R ₀₁ and R ₀₂ are not simultaneously hydrogen atoms.

The preferred alkyl group for R ₀₁ and R _{02 is} an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms. As a halogen atom, a fluorine atom, a chlorine atom, and a bromine atom are preferable, and a chlorine atom is more preferable.

As R ₀₁ and R ₀₂ , particularly preferably, one is a hydrogen atom and the other is a methyl group or a chlorine atom.

  Specific examples of the monomer represented by formula (M) in the present invention include 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, and 2,3-dimethyl-1,3. -Butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-fluoro-1,3-butadiene, 2,3-dichloro-1 , 3-butadiene, 2-cyano-1,3-butadiene.

  The binder in the present invention is a polymer obtained by copolymerizing the monomer represented by the general formula (M), and the copolymerization ratio of the monomer represented by the general formula (M) in the polymer is 10% by mass or more and 70% by mass. %, Preferably 15% to 65% by mass, more preferably 20% to 60% by mass. When the copolymerization ratio of the monomer represented by the general formula (M) is less than 10% by mass, the fusion component of the binder is decreased, and the film forming strength is deteriorated. On the other hand, when the copolymerization ratio of the monomer represented by the general formula (M) exceeds 70% by mass, the fusion component of the binder increases and the mobility of the binder increases, so that the image storability deteriorates.

  In the present invention, the other monomer that can be copolymerized with the monomer represented by formula (M) is not particularly limited, and any monomer that can be polymerized by a normal radical polymerization or ionic polymerization method is preferably used. be able to. Monomers that can be preferably used can be selected from the monomer groups (a) to (j) described in JP-A-2005-141013, “0019” to “0022”, independently and freely in combination.

  Preferred examples of the polymer obtained by copolymerizing the monomer represented by formula (M) in the present invention include a copolymer with styrene (for example, a random copolymer, a block copolymer, etc.), a copolymer with styrene and butadiene. Copolymer (for example, random copolymer, butadiene-isoprene-styrene block copolymer, styrene-butadiene-isoprene-styrene block copolymer, etc.), copolymer with ethylene-propylene, copolymer with acrylonitrile, Copolymers with isobutylene, copolymers with acrylic acid esters (for example, acrylic acid esters such as ethyl acrylate and butyl acrylate), and copolymers with acrylic acid esters and acrylonitrile (acrylic acid esters) Can be the same as mentioned above), and in this, , Copolymers of styrene is most preferred.

  Moreover, it is preferable that the polymer in this invention copolymerizes the monomer which has an acid group further in these compositions. As the acid group, carboxylic acid, sulfonic acid, and phosphoric acid are preferable. The copolymerization ratio of the acid group is preferably 1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less.

  Specific examples of the monomer having an acid group include acrylic acid, methacrylic acid, itaconic acid, p-styrenesulfonic acid sodium salt, isoprenesulfonic acid, phosphorylethyl methacrylate and the like.

  In the binder in the present invention, any polymer may be used in combination with the copolymer polymer with the monomer represented by the general formula (M). The polymer that can be used in combination is preferably transparent or translucent and colorless. Natural resins, polymers and copolymers, synthetic resins, polymers and copolymers, and other media for forming films such as those disclosed in JP-A-2005-141013 Mention may be made of the polymers described in paragraph "0025". The binder may be formed from water, an organic solvent or an emulsion.

  The binder in the present invention preferably has a glass transition temperature (Tg) in the range of −30 ° C. or more and 70 ° C. or less, more preferably in the range of −10 ° C. to 70 ° C. in terms of film forming strength and image storage stability. More preferably, it is the range of 0 degreeC-70 degreeC. It is also possible to use a blend of two or more polymers as the binder, and in this case, it is preferable that the weighted average Tg in consideration of the composition falls within the above range. Moreover, when phase-separating or having a core-shell structure, the weighted average Tg is preferably within the above range.

  This glass transition temperature (Tg) can be calculated by the following formula.

1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the mass fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. However, Σ is the sum from i = 1 to n. In addition, the value (Tgi) of the homopolymer glass transition temperature of each monomer employ | adopted the value of Polymer Handbook (3rd Edition) (J. Brandrup, EH Immergut (Wiley-Interscience, 1989)).

  The polymer used for the binder can be easily obtained by solution polymerization method, suspension polymerization method, emulsion polymerization method, dispersion polymerization method, anion polymerization method, cationic polymerization, etc., but the emulsion polymerization method obtained as a latex is most preferable. . In the emulsion polymerization method, for example, water or a mixed solvent of water and an organic solvent miscible with water (for example, methanol, ethanol, acetone, etc.) is used as a dispersion medium, and 5 mass% or more and 150 mass% with respect to the dispersion medium. Using the following monomer mixture and the total amount of monomers, an emulsifier and a polymerization initiator are used, and polymerization is carried out with stirring at 30 ° C to 100 ° C, preferably 60 ° C to 90 ° C for 3 to 24 hours. . Various conditions such as the dispersion medium, the monomer concentration, the initiator amount, the emulsifier amount, the dispersant amount, the reaction temperature, and the monomer addition method are appropriately set in consideration of the type of monomer used. Moreover, it is preferable to use a dispersing agent as needed.

  The emulsion polymerization method can be generally performed according to the following literature. “Synthetic Resin Emulsions (Edited by Taira Okuda, Hiroshi Inagaki, Published by Polymer Publishing Company (1978))”, “Application of Synthetic Latex (Takaaki Sugimura, Akio Kataoka, Junichi Suzuki, Keiji Kasahara, Published by Polymer Publishing Company (1993)) ) ”,“ Synthetic Latex Chemistry (Muroichi Muroi, published by Kobunshi Shuppankai (1970)) ”. In the emulsion polymerization method for synthesizing the polymer latex according to the present invention, a batch polymerization method, a monomer (continuous / divided) addition method, an emulsion addition method, a seed polymerization method, and the like can be selected. From the viewpoint of latex productivity, A polymerization method, a monomer (continuous / divided) addition method, and an emulsion addition method are preferred.

  The polymerization initiator only needs to have radical generating ability, such as inorganic peroxides such as persulfate and hydrogen peroxide, peroxides described in Nippon Oil & Fats Co., Ltd. organic peroxide catalog, and Wako Pure Chemical Industries, Ltd. The azo compounds described in the azo polymerization initiator catalog can be used. Among these, water-soluble peroxides such as persulfate and water-soluble azo compounds described in the Wako Pure Chemical Industries, Ltd. Azo Polymerization Initiator Catalog are preferable. Ammonium persulfate, sodium persulfate, potassium persulfate, azobis ( 2-methylpropionamidine) hydrochloride, azobis (2-methyl-N- (2-hydroxyethyl) propionamide), azobiscyanovaleric acid is more preferable, and in particular, peroxidation such as ammonium persulfate, sodium persulfate, potassium persulfate and the like. The product is preferable from the viewpoint of image preservability, solubility, and cost.

  As the addition amount of the polymerization initiator, the polymerization initiator is preferably 0.3% by mass or more and 2.0% by mass or less, and 0.4% by mass or more and 1.75% by mass or less based on the total amount of monomers. More preferably, it is 0.5 mass% or more and 1.5 mass% or less. When the amount of the polymerization initiator is less than 0.3% by mass, the image storability is lowered, and when it exceeds 2.0% by mass, the latex tends to aggregate and the coatability is lowered.

  As the polymerization emulsifier, any of an anionic surfactant, a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant can be used, but the anionic surfactant has dispersibility and image storability. From the viewpoint, it is preferable to use a sulfonic acid type anionic surfactant because polymerization stability can be secured in a small amount and it has hydrolysis resistance, and long-chain alkyl diphenyl ether disulfone represented by Perex SS-H (Kao Co., Ltd.). Acid salts are more preferable, and a low electrolyte type such as Pionine A-43-S (Takemoto Yushi Co., Ltd.) is particularly preferable.

  As the polymerization emulsifier, a sulfonic acid type anionic surfactant is preferably used in an amount of 0.1% by mass or more and 10.0% by mass or less, and 0.2% by mass or more and 7.5% by mass or less based on the total amount of monomers. It is more preferable that it is used, and it is particularly preferable that 0.3% by mass or more and 5.0% by mass or less is used. If the polymerization emulsifier is less than 0.1% by mass, stability during emulsion polymerization cannot be ensured, and if it exceeds 10.0%, the image storage stability decreases.

  For the synthesis of the polymer latex used in the present invention, it is preferable to use chelating agents described in JP-A-2005-141013, “0034” to “0036”.

  The addition amount of the chelating agent is preferably 0.01% by mass or more and 0.4% by mass or less, more preferably 0.02% by mass or more and 0.3% by mass or less, based on the total amount of monomers. It is especially preferable that it is 0.03 mass% or more and 0.15 mass% or less. When the amount of the chelating agent is less than 0.01% by mass, capture of metal ions mixed in the production process of the polymer latex becomes insufficient, stability against aggregation of the latex is lowered, and applicability is deteriorated. Moreover, when it exceeds 0.4 mass%, the viscosity of latex will rise and coatability will fall.

  A chain transfer agent is preferably used for the synthesis of the polymer latex used in the present invention. As the chain transfer agent, those described in Polymer Handbook, 3rd edition, (Wiley-Interscience, 1989) are preferable. Sulfur compounds are more preferred because they have high chain transfer ability and can be used in small amounts. Hydrophobic mercaptan-based chain transfer agents such as tert-dodecyl mercaptan and n-dodecyl mercaptan are particularly preferred.

  The amount of the chain transfer agent is preferably 0.2% by mass or more and 2.0% by mass or less, more preferably 0.3% by mass or more and 1.8% by mass or less, and more preferably 0.4% by mass or more and 1% by mass or less based on the total amount of monomers. .6% by mass or less is particularly preferable. When the amount of the chain transfer agent is less than 0.2% by mass, the film forming strength is lowered, and when it exceeds 2.0% by mass, the image storability is deteriorated.

  In emulsion polymerization, in addition to the above compounds, electrolytes, stabilizers, thickeners, antifoaming agents, antioxidants, vulcanizing agents, antifreezing agents, gelling agents, vulcanization accelerators, etc. are described in synthetic rubber handbooks, etc. These additives may be used.

(Specific examples of polymer)
Specific examples of the polymer used in the present invention include the following exemplary compounds (P-1) to (P-29). Specific examples of the polymer that can be used in the present invention are listed below, but the present invention is not limited to these specific examples. X, y, z, and z ′ in the chemical formula indicate a mass ratio of the polymer composition, and the total sum of x, y, z, and z ′ is 100%. Tg represents the glass transition temperature of the dry film obtained from the polymer.

  The polymer used in the present invention can be synthesized by a method described in “0050” to “0053” of JP-A-2005-141013.

  In the polymer latex used in the present invention, an aqueous solvent can be used as a solvent in the coating solution, but a water-miscible organic solvent may be used in combination.

  Examples of the water-miscible organic solvent include alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, ethyl acetate and dimethylformamide. The amount of these organic solvents added is preferably 50% by mass or less, more preferably 30% by mass or less of the solvent.

  The polymer latex according to the present invention preferably has a polymer concentration of 10% by mass to 70% by mass with respect to the latex liquid, more preferably 20% by mass to 60% by mass, particularly 30% by mass to 55% by mass. The following is preferable.

  The binder polymer according to the present invention preferably has an equilibrium water content of 2% by mass or less at 25 ° C. and 60% RH. More preferably, the equilibrium water content is 0.01% by mass or more and 1.5% by mass or less, and further preferably 0.02% by mass or more and 1.0% by mass or less.

  “Equilibrium moisture content at 25 ° C. and 60% RH” means that the following is the mass W1 of the polymer in a humidity-controlled equilibrium under an atmosphere of 25 ° C. and 60% RH, and the mass W0 of the polymer in an absolutely dry state at 25 ° C. Can be expressed as:

Equilibrium water content at 25 ° C. and 60% RH = [(W1-W0) / W0] × 100 (mass%)
For the definition and measurement method of moisture content, for example, Polymer Engineering Course 14, Polymer Material Testing Method (Edited by Society of Polymer Sciences, Jinshokan) can be referred to.

  In the present invention, a polymer dispersible in an aqueous solvent is particularly preferred. Examples of the dispersed state may be either latex in which fine particles of water-insoluble hydrophobic polymer are dispersed or polymer molecules dispersed in a molecular state or forming micelles. preferable. The average particle size of the dispersed particles is 1 nm or more and 50000 nm or less, preferably 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 50 nm or more and 200 nm or less. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution. Mixing two or more types having a monodispersed particle size distribution is also a preferable method for controlling the physical properties of the coating solution.

  If necessary, a hydrophilic polymer such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose may be added to the image forming layer in the invention. The amount of these hydrophilic polymers added is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total binder of the image forming layer.

  The image forming layer in the present invention is preferably formed using a polymer latex. The amount of binder in the image forming layer is such that the total binder / organic silver salt mass ratio is 1/10 to 10/1, more preferably 1/3 to 5/1, and still more preferably 1/1 to 3/1. Range.

  The mass ratio of the total binder / photosensitive silver halide in the image forming layer is in the range of 400 to 5, more preferably 200 to 10.

The total binder coating amount of the image forming layer in the present invention is preferably 0.2 g / m ² or more and 30 g / m ² or less, more preferably 1 g / m ² or more and 15 g / m ² or less, and further preferably 2 g / m ² or more. The range is 10 g / m ² or less. In the image forming layer of the present invention, a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like may be added.

  Next, the latex of the hydrophobic polymer used for the outermost layer or the non-photosensitive intermediate layer in the present invention will be described.

  Preferred embodiments of the polymer used for the latex of the hydrophobic polymer in the present invention include acrylic polymers, poly (esters), rubbers (for example, SBR resin), poly (urethanes), poly (vinyl chloride) s, poly ( Hydrophobic polymers such as vinyl acetate), poly (vinylidene chloride) s, and poly (olefins) can be preferably used. These polymers may be linear polymers, branched polymers, crosslinked polymers, so-called homopolymers obtained by polymerizing a single monomer, or copolymers obtained by polymerizing two or more types of monomers. In the case of a copolymer, it may be a random copolymer or a block copolymer. These polymers have a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 200,000. If the molecular weight is too small, the mechanical strength of the layer containing the latex is insufficient, and if it is too large, the film formability is poor and this is not preferred. A crosslinkable polymer latex is particularly preferably used.

  In the photothermographic material of the present invention, the polymer latex that can be used as a binder is a water-insoluble hydrophobic polymer dispersed as fine particles in a water-soluble dispersion medium. As the dispersion state, the polymer is emulsified in a dispersion medium, the emulsion is polymerized, the micelle is dispersed, or the polymer molecule has a partially hydrophilic structure and the molecular chain itself is molecularly dispersed. Anything may be used.

  For polymer latex, see “Synthetic Resin Emulsion (Hiraku Okuda, Hiroshi Inagaki, Published by Polymer Press (1978))”, “Application of Synthetic Latex (Takaaki Sugimura, Ikuo Kataoka, Junichi Suzuki, Keiji Kasahara, edited by Koshihara) Publication (1993)), "chemistry of synthetic latex (by Soichi Muroi, published by Kobunshi Shuppankai (1970))" and JP-A No. 64-538.

  The average particle size of the dispersed particles is preferably 1 to 50000 nm, more preferably about 5 to 1000 nm. The particle size distribution of the dispersed particles is not particularly limited, and may have a wide particle size distribution or a monodispersed particle size distribution.

  The polymer latex may be a so-called core / shell type latex in addition to a normal uniform polymer latex. In this case, it may be preferable to change the glass transition temperature between the core and the shell. The glass transition temperature (Tg) of the polymer latex polymer used for the binder has a different preferred temperature range between the polymer used for the protective layer and the back layer including the outermost layer and the polymer used for the image forming layer described later.

  Since the protective layer and the back layer including the outermost layer are in contact with various devices, a glass transition temperature of 20 ° C. to 100 ° C. is particularly preferable from the viewpoint of film strength and adhesion failure prevention, and more preferably 20 ° C. to 70 ° C. It is the range of the glass transition temperature. Further, the image forming layer promotes diffusion of photographic useful materials during heat development, and a glass transition temperature of −30 ° C. to 80 ° C. is preferable in order to obtain good photographic properties such as high Dmax and low fog, and more preferably glass transition temperature. Is 0 ° C. to 80 ° C., more preferably 10 ° C. to 70 ° C., and a particularly preferred range is 15 ° C. to 60 ° C.

  Specific examples of preferable polymer latex include the following. Below, it represents using a raw material monomer, the numerical value in a parenthesis is the mass%, and molecular weight is a number average molecular weight. When a polyfunctional monomer was used, the concept of molecular weight was not applicable because a crosslinked structure was formed, so it was described as crosslinkability, and the description of molecular weight was omitted. Tg represents the glass transition temperature.

PL-1; -MMA (70) -EA (27) -MAA (3) -latex (molecular weight 37000, Tg 61 ° C.)
PL-2; -MMA (70) -2EHA (20) -St (5) -AA (5)-latex (molecular weight 40000, Tg 59 ° C.)
PL-3; latex of -St (50) -Bu (47) -MAA (3)-(crosslinkability, Tg-17 ° C)
PL-4; latex of -St (68) -Bu (29) -AA (3)-(crosslinkability, Tg 17 ° C)
PL-5; Latex of -St (71) -Bu (26) -AA (3)-(crosslinkability, Tg 24 ° C)
PL-6; -St (70) -Bu (27) -IA (3)-latex (crosslinkable)
PL-7; latex of -St (75) -Bu (24) -AA (1)-(crosslinkability, Tg 29 ° C)
PL-8; Latex (crosslinkable) of -St (60) -Bu (35) -DVB (3) -MAA (2)-
PL-9; Latex (crosslinkable) of -St (70) -Bu (25) -DVB (2) -AA (3)-
PL-10; Latex (molecular weight 80000) of -VC (50) -MMA (20) -EA (20) -AN (5) -AA (5)-
PL-11; latex of -VDC (85) -MMA (5) -EA (5) -MAA (5)-(molecular weight 67000)
PL-12; -Et (90) -MAA (10)-latex (molecular weight 12000)
PL-13; -St (70) -2EHA (27) -AA (3) latex (molecular weight 130,000, Tg 43 ° C)
PL-14; latex of MMA (63) -EA (35) -AA (2) (molecular weight 33000, Tg 47 ° C.)
PL-15; latex of -St (70.5) -Bu (26.5) -AA (3)-(crosslinkability, Tg23 ° C)
PL-16; Latex of -St (69.5) -Bu (27.5) -AA (3)-(crosslinkability, Tg 20.5 ° C)
The abbreviations for the above structures represent the following monomers. MMA; methyl methacrylate, EA; ethyl acrylate, MAA; methacrylic acid, 2EHA; 2-ethylhexyl acrylate, St; styrene, Bu; butadiene, AA; acrylic acid, DVB; divinylbenzene, VC; vinyl chloride, AN; Vinylidene chloride, Et; ethylene, IA; itaconic acid.

  The polymer latex described above is also commercially available, and polymers described in “0026” of JP-A No. 2004-212492 can be used.

  These polymer latexes may be used alone or in combination of two or more as required.

  In the present invention, it is preferable to prepare the photographic constituent layer by applying an aqueous coating solution and then drying it. However, “aqueous” as used herein means that 60% by mass or more of the solvent (dispersion medium) of the coating solution is water. Components other than water in the coating solution include methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, dimethylformamide, ethyl acetate, diacetone alcohol, furfuryl alcohol, benzyl alcohol, diethylene glycol monoethyl ether, oxyethyl phenyl ether A water miscible organic solvent such as can be used.

The total binder amount for the outermost layer and the non-photosensitive layer containing the outer layer in the present invention is preferably in the range of 0.2 to 6.0 g / m ² , more preferably 0.5 to 4.0 g / m ² . The total binder amount for the image forming layer in the invention is preferably from 0.2 to 30 g / m ² , more preferably from 1.0 to 15 g / m ² . Total amount of binder for the back layer in the invention, 0.01~3g / m ^2, more preferably in the range of 0.05 to 1.5 g / m ^2.

  Each layer may contain a crosslinking agent for crosslinking, a surfactant for improving coating properties, and the like. Each of these layers may be provided in two or more layers. When there are two or more image forming layers, it is preferable to use a polymer latex as a binder for all layers. The protective layer is a layer provided on the image forming layer and may exist in two or more layers. In the present invention, the polymer latex is 50% by mass or more and 100% by mass or less of the binder of the outermost layer or the non-photosensitive intermediate layer. Is used. Preferably it is 60-100 mass%, More preferably, it is 70-100 mass%. This makes it possible to improve the effects of the present invention, particularly the raw storage stability. Further, the back layer is a layer provided outside the undercoat layer on the back surface side with respect to the support, and there may be two or more layers, but at least one layer, in particular, the outermost back layer is coated with polymer latex. It is preferable to use it.

The minimum film-forming temperature (MFT) of the polymer latex is preferably −30 ° C. to 90 ° C., more preferably about 0 ° C. to 70 ° C. A film-forming auxiliary may be added to control the minimum film-forming temperature. The film-forming aid is also called a temporary plasticizer and is an organic compound (usually an organic solvent) that lowers the minimum film-forming temperature of the polymer latex. ))"It is described in. Preferred film-forming aids are the following compounds, but the compounds that can be used in the present invention are not limited to the following specific examples.
Z-1: benzyl alcohol Z-2: 2,2,4-trimethylpentanediol-1,3-monoisobutyrate Z-3: 2-dimethylaminoethanol Z-4: diethylene glycol In particular, the outermost layer When forming a protective layer, it is preferable to add a film-forming aid, and the addition amount is preferably 1 to 30% by mass with respect to the solid content of the polymer latex in the coating solution for the protective layer, and Is preferably 5 to 20% by mass. Polyvinyl alcohol, methylcellulose, hydroxypropylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose and the like are preferably used as the hydrophilic polymer of the dispersion stabilizer contained in the image forming layer and the outermost layer in the present invention. Particularly preferred is polyvinyl alcohol.

  In the outermost layer in the present invention, a water-soluble polymer may be used in combination with the latex of the hydrophobic polymer as a binder in a range not exceeding 50% by mass of the total amount of the binder in the outermost layer.

  Examples of water-soluble polymers include water-soluble polymers derived from animal proteins such as gelatin and glue, which are often used in the industry, and other water-soluble polymers not derived from animal proteins. In the present invention, animal proteins Non-origin water-soluble polymers are preferred.

(Organic silver salt)
The organic silver salt according to the present invention is a non-photosensitive organic silver salt that can function as a supply source for supplying silver ions for forming a silver image in a photosensitive layer of a silver salt photothermographic dry imaging material. .

  That is, the organic silver salt according to the present invention was heated to 80 ° C. or higher in the presence of photosensitive silver halide grains (photocatalyst) having a latent image formed by exposure on the grain surface and a reducing agent. In the thermal development process, the silver salt functions as a silver ion supply source and can supply silver ions and contribute to silver image formation.

  As such a non-photosensitive organic silver salt, conventionally, silver salts of organic compounds having various chemical structures are known. For example, paragraphs “0048” to “0049” of JP-A-10-62899, European Patent Application Publication No. 803,764A1, page 18, line 24 to page 19, line 37, European Patent Application Publication No. 962,812A1, Japanese Patent Application Laid-Open No. 11-349591, Japanese Patent Application Laid-Open No. 2000- 7683, 2000-72711, 2002-23301, 2002-23303, 2002-49119, 196446, European Patent Application No. 1246001A1, European Patent Application Publication No. 1258775A1, JP 2003-140290 A, JP 2003-195445 A, 2003-295378, JP same 2003-295379, JP same 2003-295380, JP same 2003-295381 JP, described in JP-A No. 2003-270755 Publication.

  In the present invention, a silver salt of an aliphatic carboxylic acid, particularly, having 10 to 30 carbon atoms, preferably in combination with or without using various organic silver salts disclosed in the above-mentioned patent publications, etc. A silver salt of 15 to 28 long chain aliphatic carboxylic acid can be used. The molecular weight of the aliphatic carboxylic acid for producing the silver salt is preferably 200 to 500, more preferably 250 to 400. Preferred examples of the aliphatic carboxylic acid silver salt include silver behenate, silver arachidate, silver stearate, silver oleate, silver laurate, silver caproate, silver myristate, silver palmitate, and a mixture thereof. Including.

  In the present invention, among these aliphatic silver carboxylates, the silver behenate content is preferably 50 mol% or more, more preferably 80 mol% or more and 99.9 mol% or less, still more preferably 90 mol% or more and 99.99 mol%. It is preferable to use 9 mol% or less of fatty acid silver.

  Prior to the preparation of the aliphatic carboxylic acid silver salt, it is necessary to prepare an alkali metal salt of an aliphatic carboxylic acid. In this case, examples of the types of alkali metal salts that can be used include sodium hydroxide. Potassium hydroxide and lithium hydroxide. Among these, it is preferable to use one kind of alkali metal salt, for example, potassium hydroxide, but it is also preferable to use sodium hydroxide and potassium hydroxide in combination. The combined ratio is preferably such that the molar ratio of both of the above-mentioned hydroxide salts is in the range of 10:90 to 75:25. When used in the above range when reacted with an aliphatic carboxylic acid to form an alkali metal salt of an aliphatic carboxylic acid, the viscosity of the reaction solution can be controlled in a good state.

  In addition, when preparing an aliphatic carboxylate silver salt in the presence of silver halide grains having an average particle diameter of 0.050 μm or less, the alkali metal of the alkali metal salt is preferably a halide having a higher potassium ratio. It is preferable because dissolution of silver particles and Ostwald ripening are prevented. Moreover, the size of fatty acid silver salt particle | grains can be made small, so that the ratio of potassium salt is high. A preferable ratio of the potassium salt is 50 to 100% based on the total alkali metal salt used in the step of producing the aliphatic carboxylate. The concentration of the alkali metal salt is preferably 0.1 to 0.3 mol / 1000 ml.

  The average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt means the diameter of the sphere having the same volume as the volume of one particle of the non-photosensitive aliphatic carboxylic acid silver salt. The particle volume can be obtained from the projected area and thickness of the particles observed by the above, and the diameter when converted to a sphere having the same volume as that volume can be obtained by averaging. In order to control the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt, it is necessary to prepare a higher ratio of potassium salt during preparation of the aliphatic carboxylic acid silver salt as described above, or to disperse the photosensitive emulsion. This can be easily performed by appropriately adjusting the particle diameter, mill peripheral speed, and dispersion time of the zirconia beads used during dispersion of the liquid. In the present invention, the average sphere equivalent diameter of the non-photosensitive aliphatic carboxylic acid silver salt is preferably 0.05 to 0.50 μm, more preferably 0.005 μm in order to obtain a sufficient density after heat development. The thickness is 10 to 0.45 μm, particularly preferably 0.15 to 0.40 μm.

  Examples of organic silver that may be used in addition to the non-photosensitive aliphatic carboxylic acid silver salt used in the present invention include organic silver salts having a core-shell structure (Japanese Patent Laid-Open No. 2002-23303), polyvalent A silver salt of carboxylic acid (EP1246001 and JP2004-061948) and a polymer silver salt (JP2000-292881, JP2003-295378 to 2003-295281) can also be used.

  The shape of the aliphatic carboxylic acid silver salt that can be used in the present invention is not particularly limited, and may be any of a needle shape, a rod shape, a flat plate shape, and a flake shape. In the present invention, flake-shaped aliphatic carboxylic acid silver salts and short needle-shaped or rectangular parallelepiped-shaped aliphatic carboxylic acid silver salts having a major axis / minor axis length ratio of 5 or less are preferably used.

  In the present specification, the scaly organic silver salt is defined as follows. The organic silver salt is observed with an electron microscope, the shape of the organic silver salt particle is approximated to a rectangular parallelepiped, and the sides of the rectangular parallelepiped are defined as a, b, and c from the shortest side (even though c is the same as b) Good)), and calculate with the shorter numbers a and b, and find x as follows.

x = b / a
In this way, x is obtained for about 200 particles, and when the average value x (average) is obtained, particles satisfying the relationship of x (average) ≧ 1.5 are defined as flakes. Preferably, 30 ≧ x (average) ≧ 1.5, more preferably 20 ≧ x (average) ≧ 2.0. Incidentally, the needle shape is 1 ≦ x (average) <1.5.

  In the flake shaped particle, a can be regarded as a thickness of a tabular particle having a main plane with b and c as sides. The average of a is preferably 0.01 μm or more and 0.23 μm, more preferably 0.1 μm or more and 0.20 μm or less. The average c / b is preferably 1 or more and 6 or less, more preferably 1.05 or more and 4 or less, still more preferably 1.1 or more and 3 or less, and particularly preferably 1.1 or more and 2 or less.

  The particle size distribution of the organic silver salt is preferably monodispersed. Monodispersion is preferably 100% or less, more preferably 80% or less, and even more preferably 50% of the value obtained by dividing the standard deviation of the lengths of the short and long axes by the short and long axes. It is as follows. The method for measuring the shape of the organic silver salt can be determined from a transmission electron microscope image of the organic silver salt dispersion. As another method for measuring monodispersity, there is a method for obtaining the standard deviation of the volume weighted average diameter of the organic silver salt, and the percentage (variation coefficient) of the value divided by the volume weighted average diameter is preferably 100% or less, more Preferably it is 80% or less, More preferably, it is 50% or less. As a measuring method, for example, from the particle size (volume weighted average diameter) obtained by irradiating an organic silver salt dispersed in a liquid with laser light and obtaining an autocorrelation function with respect to temporal change of fluctuation of the scattered light. Can be sought.

  Known methods and the like can be applied to the production of organic silver used in the present invention and the dispersion method thereof. For example, Japanese Patent Application Laid-Open No. 10-62899, European Patent Application Publication No. 803,763A1, European Patent Application Publication No. 962,812A1, Japanese Patent Application Laid-Open No. 2001-167022, and Japanese Patent Application Laid-Open No. 2000-7683. No. 2000-72711, No. 2001-163889, No. 2001-163890, No. 2001-163828, No. 2001-33907, No. 2001-188313, No. 2001-83651, Reference can be made to JP-A Nos. 2002-6442, 2002-31870, and 2003-280135.

  A photosensitive silver salt such as photosensitive silver halide grains can coexist when the organic silver salt is dispersed. However, when silver halide grains are allowed to coexist at the time of dispersion of the organic silver salt, fog is increased and sensitivity is remarkably lowered. Therefore, it is more preferable that silver halide grains are not substantially contained at the time of dispersion. In the present invention, the amount of silver halide grains in the aqueous dispersion to be dispersed is preferably 1 mol% or less, more preferably 0.1 mol% or less with respect to 1 mol of the organic silver salt in the liquid. More preferably, the active addition of silver halide grains is not performed.

  In the present invention, a photosensitive material can be produced by mixing an organic silver salt aqueous dispersion and a photosensitive silver halide particle dispersion, but the mixing ratio of the organic silver salt and the photosensitive silver salt can be selected according to the purpose. However, the ratio of the photosensitive silver halide grains to the organic silver salt is preferably in the range of 1 to 30 mol%, more preferably 2 to 20 mol%, particularly preferably 3 to 15 mol%. Mixing two or more kinds of organic silver salt dispersions and two or more kinds of silver halide grain dispersions when mixing is a method preferably used for adjusting photographic characteristics.

The organic silver salt of the present invention can be used in a desired amount, but the silver amount is preferably 0.1 to 5 g / m ² , more preferably 0.3 to 3 g / m ² , still more preferably 0.5 to ² g / m ² . m ² .

(Photosensitive silver halide grains)
The photosensitive silver halide grains according to the present invention (hereinafter also referred to as photosensitive silver halide or silver halide) can inherently absorb light as an intrinsic property of silver halide crystals, or are artificial. In the silver halide crystal when visible light or infrared light can be absorbed by a physicochemical method, and light in any region within the light wavelength range from the ultraviolet light region to the infrared light region is absorbed. And / or silver halide crystal grains that have been processed so that physicochemical changes can occur on the crystal surface.

  The silver halide grains themselves according to the present invention can be prepared as a silver halide grain emulsion (also referred to as a silver halide emulsion) using a known method. That is, any of an acidic method, a neutral method, an ammonia method, etc. may be used, and a method 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, a combination thereof, and the like. Of these methods, the so-called controlled double jet method, in which silver halide grains are prepared while controlling the formation conditions, is preferred.

  Usually, silver halide seed grains are divided into two stages: grain nucleation and grain growth, and these may be performed continuously at a time, or nucleation (seed grain) formation and grain growth are performed separately. The method 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 in which nucleation and particle growth are performed separately, first, an aqueous silver salt solution and an aqueous halide solution are uniformly and rapidly mixed in an aqueous gelatin solution to produce nuclei (seed particles) (nucleation process). Then, silver halide grains are prepared by a grain growth process in which grains are grown while supplying an aqueous silver salt solution and an aqueous halide solution under controlled pAg, pH, and the like. After the formation of grains, a desired silver halide emulsion can be obtained by removing unnecessary salts and the like by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, or an electrodialysis method. .

  In the present invention, the grain size distribution of silver halide grains is 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, tetrahedron grains, tabular grains, spherical grains, rod-like grains, potato-like grains, etc. Among these, cubic, octahedral, 14 Planar and tabular silver halide grains are preferred.

  The average aspect ratio when using tabular silver halide grains 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 and 5,320,958, 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 sensitizing dye having crystal habit (plane) selectivity in the adsorption reaction of the 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.

  In the present invention, the low molecular weight gelatin preferably has an average molecular weight of 50,000 or less, more preferably 2,000 to 40,000, and particularly preferably 5,000 to 25,000. The average molecular weight of gelatin can be measured by gel filtration chromatography. Low molecular weight gelatin can be hydrolyzed by adding gelatin-degrading enzyme to a commonly used gelatin aqueous solution with an average molecular weight of about 100,000, heating 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 more preferably 0.05 to 3.0% by mass.

  As the silver halide grains used in the present invention, it is preferable to use a compound represented by the following general formula at the time of forming the grains.

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. This is described in Japanese Patent Publication No. 44-9497. The polyethylene oxide compound represented by the above general formula also functions as an antifoaming agent during nucleation. The 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 halide aqueous solution or both aqueous solutions. Further, the compound represented by the above general formula is preferably present for a time of at least 50% of the nucleation step, and more preferably for a time of 70% or more. The 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 usually 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 increased and the temperature at the end of nucleation is 40 ° C.) and vice versa.

The concentration of the aqueous silver salt solution and aqueous halide solution used for nucleation is preferably 3.5 mol / L or less, and more preferably used in a low concentration range of 0.01 to 2.5 mol / 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 reaction solution. × 10 ^-2 mol / min.

  The pH at the time of nucleation can usually be set in the range of 1.7 to 10, but the pH on the alkali side broadens the particle size distribution of the nuclei to be formed, and is preferably pH 2 to 6. Moreover, pBr at the time of nucleation is 0.05-3.0 normally, Preferably it is 1.0-2.5, More preferably, it is 1.5-2.0.

  In the present invention, the average grain size of the silver halide grains is usually 10 to 50 nm, preferably 10 to 40 nm, and more preferably 10 to 35 nm. If the average grain size of the silver halide grains is smaller than 10 nm, the image density decreases, or the light irradiation image storage stability (the image obtained by heat development is used for diagnosis in a bright room or stored in a bright room) Storage stability) may be deteriorated. On the other hand, if it exceeds 50 nm, the image density may decrease.

  The average grain diameter referred to here is the length of the edge of the silver halide grains when the silver halide grains contained in the silver halide grain emulsion are cubic or octahedral so-called normal crystals. To tell. 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 addition, when it is not a normal crystal, for example, in the case of spherical particles, rod-shaped particles, etc., the diameter when considering a sphere equivalent to the volume of the silver halide grains is calculated as the particle size. The measurement was performed using an electron micrograph, and the average particle size was determined by averaging the measured values of the particle size of 300 particles.

  In the present invention, the gradation of the image density can be adjusted by using silver halide grains having an average particle diameter of 55 to 100 nm and silver halide grains having an average particle diameter of 10 to 50 nm in combination. In addition, the image density can be improved, and the decrease in image density over time can be improved (smaller). The ratio (mass ratio) of silver halide grains having an average particle diameter of 10 to 50 nm and silver halide grains having an average particle diameter of 55 to 100 nm is preferably 95: 5 to 50:50, more preferably 90. : 10-60: 40.

  As described above, when two types of silver halide grain emulsions having an average particle diameter are used, the two types of silver halide emulsions may be mixed and contained in the photosensitive layer. In order to adjust the gradation, it is also preferable that the photosensitive layer is composed of two or more layers, and the silver halide grain emulsions having the two average grain sizes are separately contained in each layer.

(Silver halide grains having a silver iodide content of 5 mol% to 100 mol%)
As the silver halide grains according to the present invention, silver halide grains containing silver iodide can be preferably used. As the halogen composition, the silver iodide content is preferably 5 mol% or more and 100 mol% or less. More preferably, they are 40 mol% or more and 100 mol% or less, More preferably, they are 70 mol% or more and 100 mol% or less, Especially preferably, they are 90 mol% or more and 100 mol% or less. If the silver iodide content is in this range, the intra-grain halogen composition distribution may be uniform, may be changed stepwise, or may be continuously changed. Further, silver halide grains having a core / shell structure with a high silver iodide content inside and / or on the surface can also be preferably used. A preferable structure is a 2- to 5-fold structure, more preferably 2- to 4-fold core / shell particles.

  Examples of the method for introducing silver iodide into the silver halide grains according to the present invention include a method of adding an alkali iodide aqueous solution during grain formation, fine grain silver iodide, fine grain silver iodobromide, fine grain silver iodochloride, fine grain iodine. A method of adding at least one fine particle of silver chlorobromide and a method using an iodide ion releasing agent described in JP-A-5-323487 and JP-A-6-11780 are preferred.

  The silver halide grains according to the present invention preferably exhibit direct transition absorption derived from the silver iodide crystal structure at a wavelength between 350 nm and 440 nm. Whether these silver halides have light absorption of direct transition can be easily distinguished by the fact that exciton absorption due to direct transition is observed in the vicinity of 400 nm to 430 nm.

(Heat conversion internal latent image type silver halide grains)
The photosensitive silver halide grain according to the present invention is preferably a silver halide grain whose surface sensitivity is lowered by converting from a surface latent image type to an internal latent image type by heat development. That is, in the exposure before thermal development, a latent image that can function as a catalyst for a development reaction (reduction reaction of silver ions by a silver ion reducing agent) is formed on the surface of the silver halide grains, and the exposure after the thermal development process has passed. Then, since many latent images are formed inside the surface of the silver halide grains, the silver halide grains are characterized in that the formation of latent images on the surface is suppressed. It has not been known in the past to use silver halide grains whose latent image forming function greatly changes before and after the heat development processing as a dry imaging material.

  In general, when photosensitive silver halide grains are exposed, the silver halide grains themselves or spectral sensitizing dyes adsorbed on the surface of the photosensitive silver halide grains are photoexcited to freely move electrons. Although generated, these electrons are competitively trapped (captured) by an electron trap (photosensitive center) existing on the surface of the silver halide grain or an electron trap inside the grain. Therefore, if there are more chemical sensitization centers (chemical sensitization nuclei) and dopants effective as electron traps on the surface than the inside of the silver halide grains, a latent image is preferentially formed on the surface and development is possible. It becomes. On the contrary, when there are more chemical sensitization centers (chemical sensitization nuclei) and dopants effective as electron traps in the inside than the silver halide grain surface, a latent image is preferentially formed inside, and the surface Development becomes difficult. In other words, in the former case, the surface sensitivity is higher than in the interior, and in the latter case, it can be said that the surface sensitivity is lower than in the interior (reference: (1) edited by TH James, “The Theory of the Photographic Process”. “Fourth Edition, Macmillan Publishing Co., Ltd. 1977, (2) The Japan Photographic Society,“ Revised Photographic Engineering Basics (Silver Salt Photography) ”, Corona, 1998).

  In the photosensitive silver halide grain according to the present invention, it is preferable in terms of sensitivity and image storage stability to contain a dopant functioning as an electron trapping dopant at least during exposure after heat development. .

  In addition, a dopant that functions as a hole trap during the exposure for image formation before heat development, changes in the heat development process, and functions as an electron trap after heat development, Particularly preferred.

  The electron trapping dopant used here is an element or compound other than silver and halogen constituting silver halide grains, and the dopant itself has a property of trapping (capturing) free electrons, or the dopant is halogen. It is the one in which a site such as an electron trapping lattice defect is generated by being contained in a silver halide grain. For example, a metal ion other than silver or a salt or complex thereof, a chalcogen (oxygen group element) such as sulfur, selenium or tellurium, or an inorganic compound or organic compound containing a nitrogen atom or a metal complex thereof, a rare earth ion or a complex thereof, etc. Can be mentioned.

  Examples of metal ions or salts or complexes thereof include lead ions, bismuth ions, gold ions, etc., or lead bromide, lead nitrate, lead carbonate, lead sulfate, bismuth nitrate, bismuth chloride, bismuth trichloride, bismuth carbonate, sodium bismuthate, Examples thereof include chloroauric acid, lead acetate, lead stearate, bismuth acetate and the like.

  As the compound containing chalcogen such as sulfur, selenium, and tellurium, various chalcogen-releasing compounds generally known as chalcogen sensitizers in the photographic industry can be used. Moreover, as an organic substance containing chalcogen or nitrogen, a heterocyclic compound is preferable. For example, imidazole, pyrazole, pyridine, pyrimidine, pyrazine, pyridazine, triazole, triazine, 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, cinnoline, tetrazole, thiazole, o Sasol, benzimidazole, benzoxazole, benzthiazole, a tetrazaindene.

  The above heterocyclic compound may have a substituent, and the alkyl group, alkenyl group, aryl group, alkoxy group, aryloxy group, acyloxy group, acyl group, alkoxycarbonyl group are preferable as the substituent. , 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 and heterocyclic group, more preferably alkyl group, aryl group, alkoxy group, aryloxy group, acyl group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonyl group Amino 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 used in the present invention include groups 6 to 11 in the periodic table so that they function as electron trapping dopants as described above or as hole trapping dopants. Transition metal ions belonging to the above may be contained by chemically adjusting the oxidation state of the metal with a ligand or the like. As the transition metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, and Pt are preferable.

  In the present invention, the above various dopants may be used alone or in combination of two or more of the same or different compounds or complexes. However, at least one kind needs to function as an electron trapping dopant at the time of exposure after thermal development. These dopants may be introduced into the silver halide grains in any chemical form.

  In the present invention, an aspect of doping by using any one of Ir or Cu complex or salt alone is not very preferable.

The preferable content of the dopant is preferably in the range of 1 × 10 ⁻⁹ to 1 × 10 mol and more preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol with ^respect to 1 mol of silver. Furthermore, 1 * 10 ^{< -6} > ^-1 * 10 ^<-2> mol is preferable.

  However, since the optimum amount depends on the kind of dopant, the grain size and shape of the silver halide grains, and other environmental conditions, it is preferable to examine optimization of the dopant addition conditions according to these conditions.

  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 represents a transition metal selected from Group 6 to 11 elements in the periodic table, L represents a ligand, and m represents 0,-, 2-, 3-, or 4-. Specific examples of the ligand represented by L include halogen ions (for example, fluorine ion, chlorine ion, bromine ion, iodine ion), cyanide, cyanate, thiocyanate, selenocyanate, tellurocyanate, azide and aquo. Each ligand includes nitrosyl, thionitrosyl, and the like, preferably aco, nitrosyl, thionitrosyl, and the like. 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 In addition, it may be added at any stage before or after chemical sensitization, but it is particularly preferably added at the stage of nucleation, growth and physical ripening, and more preferably at the stage of nucleation and growth, Most preferably, it is added in the latter half of nucleation or immediately after. In addition, it may be divided and added several times, and can be uniformly contained in the silver halide grains. For example, 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 required 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 physical ripening, or at the time of chemical ripening.

  In addition, a nonmetallic dopant can also be introduce | transduced inside a silver halide by the method similar to said metallic dopant.

  In the imaging material according to the present invention, whether or not the above dopant has an electron trapping property can be evaluated by a method generally used in the photographic industry as follows. That is, a silver halide emulsion comprising silver halide grains doped with the above-mentioned dopant or a decomposition product thereof in silver halide grains is subjected to a photoconductivity measurement by a microwave photoconductivity measurement method or the like, and the halogenation does not contain a dopant. It can be evaluated by measuring the degree of decrease in photoconduction with a silver grain emulsion as a reference. Alternatively, it can be performed by a comparative experiment of the internal sensitivity and surface sensitivity of the silver halide grains.

  Alternatively, a method for evaluating the effect of the electron trapping dopant according to the present invention after preparing a photothermographic dry imaging material is, for example, by heating the imaging material under the same conditions as normal practical thermal development conditions before exposure. Then, for a certain period of time (for example, 30 seconds), white light or light in a specific spectral sensitization region (when spectral sensitization is performed on laser light in a specific wavelength region, In the case of spectral sensitization to infrared light, infrared light, light in the photosensitive region unique to silver halide grains, for example, blue light in the case of sensitization to blue light) It can be obtained on the basis of a characteristic curve (sensitometry curve) obtained by exposing through a wedge, or by exposing the photosensitive material surface illuminance of the laser light in stages, and further performing thermal development under the same thermal development conditions as described above. Sensitivity It can be evaluated by comparing the sensitivity of the imaging material using the silver halide grain emulsion containing no trapping dopant. That is, it can be confirmed by confirming that the sensitivity of the former sample containing the silver halide grain emulsion containing the dopant according to the present invention is lower than the sensitivity of the latter sample not containing the dopant.

In addition, after exposing the material for a certain period of time by white light or light in a specific spectral sensitization region through an optical wedge, or by changing the illuminance of the photosensitive material surface of the laser light stepwise, a normal practical use For the sensitivity (S ₁ ) obtained based on the characteristic curve obtained when thermal development is performed under the thermal thermal development conditions, heating is performed under the same conditions as the thermal development conditions before exposure, and then the same as the exposure described above. The sensitivity (S ₂ ) obtained on the basis of a characteristic curve obtained by exposure under exposure conditions and heat development under the same development conditions as the above heat development is 1/10 or less as a relative ratio (S ₂ / S ₁ ), preferably Is less than 1/20, and in the case of an imaging material obtained by chemically sensitizing a silver halide grain emulsion, the sensitivity is preferably 1/50 or less. Furthermore, it is most preferable that the surface sensitivity after heat development is substantially zero in both cases where chemical sensitization is not performed and when chemical sensitization is performed.

  Here, the normal heat development condition means that a silver salt photothermographic dry imaging material is heat-developed using a commercially available laser imager in a medical institution such as a hospital, and an image suitable for diagnostic use is obtained. In the case of obtaining, it refers to conditions that are in an appropriate range for conditions such as temperature, development time, and environmental humidity.

  The silver halide grains according to the present invention may be added to the photosensitive layer by any method. For example, the silver halide grains of the present invention, in particular, the heat conversion internal latent image type silver halide grains may be prepared in advance and added to a solution for preparing aliphatic carboxylic acid silver salt grains. The silver halide grain preparation step and the aliphatic carboxylic acid silver salt salt preparation step can be handled separately, which is preferable in terms of production control. In addition, it is more preferable to prepare silver halide grains and aliphatic carboxylate grains of the present invention separately and add them to the photosensitive layer preparation liquid immediately before the coating process.

  Separately prepared photosensitive silver halide grains are freed of unnecessary salts by a desalting step by a known desalting method such as a noodle method, a flocculation method, an ultrafiltration method, an electrodialysis method, or the like. Although it can be salted, it can also be used without desalting.

  The silver halide grains according to the present invention are used in an amount of 0.001 to 0.7 mol, preferably 0.03 to 0.5 mol, per mol of the aliphatic carboxylic acid silver salt.

(Chemical sensitization)
The photosensitive silver halide grains according to the present invention can be chemically sensitized. 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 Thus, it is possible to form and impart a chemical sensitization center (chemical sensitization nucleus) capable of capturing electrons or holes generated by photoexcitation of photosensitive silver halide grains or spectral sensitizing dyes on the grains. 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.

  These organic sensitizers are disclosed in JP-A-60-150046, JP-A-4-109240, JP-A-11-218874, JP-A-11-218875, JP-A-11-218876, JP-A-11-194447, etc. Organic sensitizers having various structures can be used, and among them, 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 It is preferable. In particular, a thiourea derivative having a heterocyclic group and a triphenylphosphine sulfide derivative are preferred.

  As a method for chemical sensitization, techniques according to various chemical sensitization techniques conventionally used in the production of conventional silver halide light-sensitive materials for wet processing can be used (reference: (1) T Edited by H. James “The Theory of the Photographic Process” 4th edition, Macmillan Publishing Co., Ltd., 1977, (2) The Japan Photographic Society, “Basics of Photographic Engineering (Silver Salt Photography), Corona, 1979) In particular, when the silver halide grain emulsion is previously chemically sensitized and then mixed with non-photosensitive organic silver salt grains, it can be chemically sensitized by a conventional method.

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 environmental conditions for chemical sensitization are 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. In particular, it may be preferable to perform chalcogen sensitization using an organic sensitizer containing a chalcogen atom in the presence of an oxidizing agent capable of oxidizing silver nuclei. The sensitizing conditions in this case are preferably 6 to 11 as pAg, more preferably 7 to 10, pH 4 to 10, more preferably 5 to 8, and the temperature increases at 30 ° C. or lower. It is preferable to give a feeling.

  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, examples of the heterocyclic ring include 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, these rings Can be mentioned, for example, a triazolotriazole ring, a diazaindene ring, a triazaindene ring, a pentaazaindene ring, and the like. 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, tetrahydroxyazaindene, 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. You may have.

The amount of the heterocyclic compound 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 in the range of ˜1 mol, preferably in the range of 10 ⁻⁴ to 10 ⁻¹ mol.

  The photosensitive silver halide according to 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. The gold sensitization technique disclosed in JP-A-11-194447 is useful as a reference.

  In addition to the above-described sensitization methods, reduction sensitization methods and the like can also be used. Examples of reduction sensitization shell-like compounds include ascorbic acid, thiourea dioxide, stannous chloride, hydrazine derivatives, A borane compound, 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.

  In the present invention, the silver halide grains subjected to chemical sensitization may be formed in the presence of an aliphatic carboxylic acid silver salt, or in the absence of the organic silver salt, A mixture of the two may be used.

  In the present invention, when chemical sensitization is performed on the surface of the photosensitive silver halide grains, it is necessary that the chemical sensitization effect substantially disappears after the thermal development process. Here, the chemical sensitization effect substantially disappears when the sensitivity of the imaging material obtained by the chemical sensitization technique is 1.1 when the chemical sensitization is not performed after the thermal development process. Say to decrease to less than double. In order to eliminate the chemical sensitization effect in the heat development process, an oxidant capable of destroying the chemical sensitization center (chemical sensitization nucleus) by an oxidation reaction at the time of heat development, for example, the above-mentioned halogen radical releasing compound, etc. It is necessary to contain an appropriate amount of the above in the emulsion layer and / or the non-photosensitive layer of the imaging material. The content of the oxidizing agent is preferably adjusted in consideration of the oxidizing power of the oxidizing agent, the reduction range of the chemical sensitization effect, and the like.

(Spectral sensitization)
The photosensitive silver halide in the present invention is 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, US Pat. No. 4,639,414, No. 4,740,455, No. 4,741,966, No. 4,751,175, No. 4,835,096 can be used.

  Useful sensitizing dyes used in the present invention include, for example, Research Disclosure (hereinafter abbreviated as RD) 17643IV-A (December 1978 p.23), RD18431X (August 1978 p.437). It is described in the literature described or cited. 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, a sensitizing dye having spectral sensitivity particularly in the infrared can also be used. Examples of infrared spectral sensitizing dyes preferably used include infrared spectral sensitization disclosed in US Pat. Nos. 4,536,473, 4,515,888, 4,959,294, and the like. Examples include dyes.

  In the silver salt photothermographic dry imaging material used in the thermal development method of the present invention, the sensitizing dye represented by the general formula (1) and the general formula (described in the specification of US Published Patent Application 2004/0224266) It is preferable to select and contain at least one of the sensitizing dyes represented by 2), among the sensitizing dyes represented by the general formula (5) and the general formula (6). It is more preferable to select and contain at least one selected from the above. It is particularly preferable to use the sensitizing dye represented by the general formula (5) and the sensitizing dye represented by the general formula (6) in combination for improving the exposure wavelength dependency at the time of exposure.

  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 this method.

  These infrared sensitizing dyes may be added at any time after the silver halide is prepared. For example, silver halide grains or halogens may be added in a so-called solid dispersion state added to a solvent or dispersed in a fine particle form. It can be added to a light-sensitive emulsion containing silver halide grains / aliphatic carboxylic acid silver salt grains. 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. Thus, dispersion of the chemical sensitization central core can be prevented, and high sensitivity and low fog can be achieved.

  In the present invention, one kind of spectral sensitizing dye may be used alone, but as described above, it is preferable to use a combination of plural kinds of spectral sensitizing dyes. The combination is often used for the purpose of supersensitization and enlargement or adjustment of the photosensitive wavelength region.

  The emulsion containing the photosensitive silver halide and the aliphatic carboxylic acid silver salt used in the silver salt photothermographic dry imaging material of the present invention is not only a sensitizing dye but also a dye having no spectral sensitizing action itself or visible light. In the emulsion, a substance that does not substantially absorb the color and expresses a supersensitization effect may be contained 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, 43-4933, JP-A-59-19032, JP-A-59-192242, JP-A-5-341432, and the like. As supersensitizers, heteroaromatic mercapto represented by the following can be used. A compound or a mercapto derivative compound is preferred.

Ar-SM
[Wherein, M 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. ]
Preferably, the heteroaromatic ring is 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 are also included.

  In addition, mercapto derivative compounds that substantially produce the above mercapto compounds when contained in a dispersion of an aliphatic carboxylic acid silver salt or silver halide grain emulsion are 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 includes, for example, a halogen atom (for example, chlorine, bromine, iodine), a hydroxyl group, an amino group, a carboxyl group, and an alkyl group (for example, one or more carbon atoms, preferably 1 to 4 carbon atoms). It may have a substituent selected from the group consisting of those having a carbon atom) and alkoxy groups (for example, those having 1 or more carbon atoms, preferably 1 to 4 carbon atoms).

  In addition to the supersensitizer described above, macrocycles having heteroatoms disclosed in JP-A No. 2001-330918 can also be used as the supersensitizer.

  The supersensitizer according to the present invention is preferably used in an amount of 0.001 to 1.0 mol per mol of silver in a photosensitive layer containing an organic silver salt and silver halide grains. Particularly preferred is an amount of 0.01 to 0.5 mole per mole of silver.

  In the present invention, it is necessary that the spectral sensitizing dye is adsorbed on the surface of the photosensitive silver halide grain to effect spectral sensitization, and that the spectral sensitizing effect should substantially disappear after the thermal development process. It is. Here, the spectral sensitization effect substantially disappears when the sensitivity of the imaging material obtained with a sensitizing dye, supersensitizer, etc. is the sensitivity when the spectral sensitization is not performed after the thermal development process. It means to decrease to 1.1 times or less.

  In order to eliminate the spectral sensitization effect in the thermal development process, use a spectral sensitizing dye that is easily detached from the silver halide grains by heat during thermal development or / and destroy the spectral sensitizing dye by an oxidation reaction. It is necessary to contain an appropriate amount of an oxidizing agent that can be formed, for example, the above-mentioned halogen radical releasing compound in the emulsion layer and / or the non-photosensitive layer of the imaging material. The content of the oxidizing agent is preferably adjusted in consideration of the oxidizing power of the oxidizing agent, the reduction range of the spectral sensitization effect, and the like.

(Reducing agent)
The reducing agent according to the present invention can reduce silver ions in the photosensitive layer and is also referred to as a developer.

  In the present invention, as a silver ion reducing agent, in particular, a compound represented by the following general formula (RD1) is used alone as at least one reducing agent, or in combination with a reducing agent having another different chemical structure. Use.

[In General Formula (RD1), X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group, or a heterocyclic group. At least one of R ₂ represents a secondary or tertiary alkyl group and may be the same or different. R ₃ represents an alkyl group having 1 to 20 carbon atoms in which at least one group has a hydroxyl group as a substituent, or an alkyl group having 1 to 20 carbon atoms in which a group capable of forming a hydroxyl group by being deprotected is used as a substituent. Represents a group, which may be the same or different. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
In the present invention, a compound of (RD1) and a compound of the following general formula (RD2) can be used in combination in order to control the heat development characteristics.

[Wherein, X ₂ represents a chalcogen atom or CHR ₅ , and R ₅ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. R ₆ represents an alkyl group, which may be the same or different, but is not a secondary or tertiary alkyl group. R ₇ represents a hydrogen atom or a group that can be substituted on a benzene ring. R ₈ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
As the combined ratio, [the mass of the compound of (RD1a)]: [the mass of the compound of general formula (RD2)] is preferably 5:95 to 45:55, more preferably 10:90 to 40: 60.

In the general formula (RD1), X ₁ represents a chalcogen atom or CHR ₁ . The chalcogen atom is sulfur, selenium or tellurium, preferably a sulfur atom. R ₁ in CHR ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. The halogen atom is a fluorine atom, a chlorine atom, a bromine atom or the like, and the alkyl group is preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, and hexyl. Alkenyl groups such as vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, Examples of the aryl group include a benzene ring and a naphthalene ring, and examples of the heterocyclic group include thiophene, furan, imidazole, pyrazole, and pyrrole.

  These groups may further have a substituent. Specific examples of the substituent include a halogen atom (fluorine, chlorine, bromine, etc.), an alkyl group (methyl, ethyl, propyl, butyl, pentyl, i-pentyl). , 2-ethylhexyl, octyl, decyl, etc.), cycloalkyl groups (cyclohexyl, cycloheptyl, etc.), alkenyl groups (ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl) -3-butenyl, etc.), cycloalkenyl groups (1-cycloalkenyl, 2-cycloalkenyl groups, etc.), alkynyl groups (ethynyl, 1-propynyl, etc.), alkoxy groups (methoxy, ethoxy, propoxy, etc.), alkylcarbonyloxy groups (Acetyloxy, etc.), alkylthio groups (methylthio, trifluoromethylthio, etc.), Sil group (acetyl group, benzoyl group), carboxyl group, alkylcarbonylamino group (acetylamino etc.), ureido group (methylaminocarbonylamino etc.), alkylsulfonylamino group (methanesulfonylamino etc.), alkylsulfonyl group (methanesulfonyl) , Trifluoromethanesulfonyl, etc.), carbamoyl group (carbamoyl, N, N-dimethylcarbamoyl, N-morpholinocarbonyl, etc.), sulfamoyl group (sulfamoyl, N, N-dimethylsulfamoyl, morpholinosulfamoyl etc.), trifluoromethyl Group, hydroxyl group, nitro group, cyano group, alkylsulfonamide group (methanesulfonamide, butanesulfonamide, etc.), alkylamino group (amino, N, N-dimethylamino, N, N-diethylamino) Etc.), sulfo group, phosphono group, sulfite group, sulfino group, alkylsulfonylaminocarbonyl group (methanesulfonylaminocarbonyl, ethanesulfonylaminocarbonyl etc.), alkylcarbonylaminosulfonyl group (acetamidesulfonyl, methoxyacetamidosulfonyl etc.), alkynyl Examples thereof include aminocarbonyl groups (acetamidocarbonyl, methoxyacetamidocarbonyl, etc.), alkylsulfinylaminocarbonyl groups (methanesulfinylaminocarbonyl, ethanesulfinylaminocarbonyl, etc.) and the like. Moreover, when there are two or more substituents, they may be the same or different. A particularly preferred substituent is an alkyl group.

R ₂ represents an alkyl group, at least one of which is a secondary or tertiary alkyl group. The alkyl group is preferably a substituted or unsubstituted one having 1 to 20 carbon atoms, specifically, methyl, ethyl, propyl, i-propyl, butyl, i-butyl, t-butyl, t-pentyl, t-amyl. , T-octyl, cyclohexyl, cyclopentyl, 1-methylcyclohexyl, 1-methylcyclopropyl and the like.

Although the substituent of the alkyl group is not particularly limited, for example, aryl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, acyl group, carbamoyl group , Ester groups, halogen atoms and the like. Or it may form a saturated ring with (R _{4) n} and (R _{4) m.} R ₂ is preferably a secondary or tertiary alkyl group, and preferably has 2 to 20 carbon atoms. A tertiary alkyl group is more preferable, t-butyl, t-amyl, t-pentyl and 1-methylcyclohexyl are more preferable, and t-butyl and t-amyl are most preferable.

Among the compounds represented by the general formula (RD1), R ₃ is an alkyl group having 3 to 20 carbon atoms having a hydroxyl group as a substituent, or a group capable of forming a hydroxyl group by deprotection. It is preferable that R ₃ is an alkyl group having 3 to 20 carbon atoms, and more preferably, R ₃ is an alkyl group having 3 to 10 carbon atoms having a hydroxyl group as a substituent, or forms a hydroxyl group by being deprotected. It is a C3-C10 alkyl group which has a group which can be used as a substituent. When the carbon number of the alkyl group is within this range, it is preferable in that an image suitable for diagnosis within an average gradation of 1.8 to 6.0 can be obtained without causing the image to be hardened. R ₃ is particularly preferably an alkyl group having 3 to 5 carbon atoms having a hydroxyl group as a substituent. Examples of R ₃ include 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl and the like. These groups may further have a substituent, and the substituents mentioned in the above R ₁ can be used as the substituent.

  The group that can be deprotected to form a hydroxyl group is preferably a group that forms a hydroxyl group by deprotection by the action of an acid and / or heat.

  Specifically, ether groups (methoxy groups, tert-butoxy groups, allyloxy groups, benzyloxy groups, triphenylmethoxy groups, trimethylsilyloxy groups, etc.), hemiacetal groups (tetrahydropyranyloxy groups, etc.), ester groups (acetyl) Oxy group, benzoyloxy group, p-nitrobenzoyloxy group, formyloxy group, trifluoroacetyloxy group, pivaloyloxy group, etc.), carbonate group (ethoxycarbonyloxy group, phenoxycarbonyloxy group, tert-butyloxycarbonyloxy group, etc.) ), Sulfonate groups (p-toluenesulfonyloxy group, benzenesulfonyloxy group etc.), carbamoyloxy groups (phenylcarbamoyloxy group etc.), thiocarbonyloxy groups (benzylthiocarbonyloxy group etc.), Ester group, sulfenates group (2,4-dinitrobenzene sulfenyl group and the like).

R ₃ is most preferably a primary alkyl group having 3 to 5 carbon atoms having a hydroxyl group or a precursor group thereof, such as 3-hydroxypropyl. The most preferred combination of R ₂ and R _3, R ₂ is a tertiary alkyl group (t-butyl, t-amyl, t-pentyl, 1-methylcyclohexyl, etc.) and, R ₃ is a hydroxyl group or its precursor group And a primary alkyl group having 3 to 10 carbon atoms (3-hydroxypropyl, 4-hydroxybutyl, etc.). A plurality of R ₂ and R ₃ may be the same or different.

R ₄ represents a hydrogen atom or a group that can be substituted on the benzene ring, and specifically, an alkyl group having 1 to 25 carbon atoms (methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl, cyclohexyl). Etc.), halogenated alkyl groups (trifluoromethyl, perfluorooctyl etc.), cycloalkyl groups (cyclohexyl, cyclopentyl etc.), alkynyl groups (propargyl etc.), glycidyl groups, acrylate groups, methacrylate groups, aryl groups (phenyl etc.) , Heterocyclic groups (pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl, pyrimidinyl, pyridazinyl, selenazolyl, sriphoranyl, piperidinyl, pyrazolyl, tetrazolyl, etc.), halogen atoms (chlorine, bromine, iodine, fluorine), alkoxy groups ( Methoxy Ethoxy, propyloxy, pentyloxy, cyclopentyloxy, hexyloxy, cyclohexyloxy, etc.), aryloxy groups (phenoxy, etc.), alkoxycarbonyl groups (methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl, etc.), aryloxycarbonyl groups ( Phenyloxycarbonyl, etc.), sulfonamide groups (methanesulfonamide, ethanesulfonamide, butanesulfonamide, hexanesulfonamide group, cyclohexanesulfonamide, benzenesulfonamide, etc.), sulfamoyl groups (aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl) , Butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pi Lysylaminosulfonyl, etc.), urethane groups (methylureido, ethylureido, pentylureido, cyclohexylureido, phenylureido, 2-pyridylureido, etc.), acyl groups (acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl, etc.) ), Carbamoyl group (aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl group, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl), amide group (acetamide, propionamide, butanamide, hexane Amide, benzamide, etc.), sulfonyl group (methylsulfonyl, ethylsulfonyl, butylsulfonyl, cyclohexyl) Sulfonyl, phenylsulfonyl, 2-pyridylsulfonyl, etc.), amino group (amino, ethylamino, dimethylamino, butylamino, cyclopentylamino, anilino, 2-pyridylamino, etc.), cyano group, nitro group, sulfo group, carboxyl group, hydroxyl group Group, oxamoyl group and the like. These groups may be further substituted with these groups. n and m represent an integer of 0 to 2, and most preferably n and m are 0.

R ₄ may form a saturated ring with R ₂ and R ₃ . R ₄ is preferably a hydrogen atom, a halogen atom or an alkyl group, more preferably a hydrogen atom. A plurality of R ₄ may be the same or different.

In general formula (RD2), R ₅ is the same group as R _1, and R ₈ is the same group as R ₄ . R ₆ represents an alkyl group, which may be the same or different, but is not a secondary or tertiary alkyl group.

R ₇ represents a hydrogen atom or a group that can be substituted on a benzene ring. Examples of groups that can be substituted on the benzene ring include halogen atoms such as fluorine, chlorine, bromine, alkyl groups, aryl groups, cycloalkyl groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, amino groups, acyl groups, and acyloxy groups. , Acylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, alkylthio group, sulfonyl group, alkylsulfonyl group, sulfinyl group, cyano group, heterocyclic group and the like.

R ₇ is preferably methyl, ethyl, i-propyl, t-butyl, cyclohexyl, 1-methylcyclohexyl, 2-hydroxyethyl, 3-hydroxypropyl and the like. More preferred are methyl and 3-hydroxypropyl.

  The alkyl group is preferably a substituted or unsubstituted one having 1 to 20 carbon atoms, and specific examples thereof include methyl, ethyl, propyl, butyl and the like.

  Although the substituent of the alkyl group is not particularly limited, for example, aryl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acylamino group, sulfonamido group, sulfonyl group, phosphoryl group, acyl group, carbamoyl group , Ester groups, halogen atoms and the like.

R ₆ may form a saturated ring with (R ₈ ) _n and (R ₈ ) _m . R ₆ is preferably methyl. Among the compounds represented by the general formula (RD2), compounds preferably used are compounds satisfying the general formula (S) and the general formula (T) described in EP 1,278,101, Specific examples include compounds (1-24), (1-28) to (1-54), and (1-56) to (1-75) described in p21 to p28.

  Specific examples of the compounds represented by general formula (RD1) and general formula (RD2) are shown below, but the present invention is not limited to these.

  These bisphenol compounds represented by the general formula (RD1) and general formula (RD2) can be easily synthesized by a conventionally known method.

  In the present invention, examples of the reducing agent that can be used in combination include US Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, RD17029 and 29963. And reducing agents described in JP-A-11-119372 and JP-A-2002-62616.

The amount of the reducing agent including the compound represented by the general formula (RD1) is preferably 1 × 10 ⁻² to 10 mol, particularly preferably 1 × 10 ^{−2 to} 1.5 mol, per mol of silver. It is.

(Image tone)
Next, the color tone of an image obtained by thermally developing a silver salt photothermographic dry imaging material will be described.

  Regarding the color tone of an output image for medical diagnosis such as a conventional X-ray photographic film, it is said that a cold tone image tone is easier for a reader to obtain a more accurate diagnostic observation result. Here, the cool image tone means a pure black tone or a bluish black tone of a black image. On the other hand, the warm image tone is said to be a warm black tone with a black image, but in order to allow a more precise quantitative discussion, the International Lighting Commission (CIE) ), Based on the recommended expression.

The terms “more cold” and “more warm” regarding the color tone can be expressed by the hue angle hab at the minimum density Dmin and the optical density D = 1.0. That is, the hue angle hab is expressed by 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 by the International Commission on Illumination (CIE) in 1976. Using the following formula.

hab = tan ⁻¹ (b ^* / a ^* )
As a result of examination by the expression method based on the hue angle, the hue of the photothermographic dry imaging material of the present invention after development is preferably such that the range of the hue angle hab is 180 degrees <hab <270 degrees, more preferably 200 degrees. It has been found that degrees <hab <270 degrees, most preferably 220 degrees <hab <260 degrees. This is disclosed in Japanese Patent Laid-Open No. 2002-6463.

Conventionally, the CIE 1976 (L ^* u ^* v ^* ) color space or the (L ^* a ^* b ^* ) color space near the optical density of 1.0 is specified as u ^* , v ^* or a ^* , b ^* . It is known that a diagnostic image with a favorable color tone can be obtained by adjusting to a numerical value, and is described in, for example, Japanese Patent Application Laid-Open No. 2000-29164.

However, as a result of further intensive studies on the silver salt photothermographic dry imaging material of the present invention, the horizontal axis is u ^* or a in the CIE 1976 (L ^* u ^* v ^* ) color space or (L ^* a ^* b ^* ) color space. ^{* When} plotting u ^* , v ^* or a ^* , b ^* at various photographic densities on a graph with the vertical axis representing v ^* or b ^* , a linear regression line is created. It was found that by adjusting the value to a specific range, it has a diagnostic ability equal to or higher than that of a conventional wet type silver salt photosensitive material. A preferable range of conditions is described below.

(1) The silver salt photothermographic dry imaging material was measured for each of the optical densities of 0.5, 1.0, 1.5 and the lowest optical density of the silver image obtained after the heat development processing, and CIE 1976 (L ^* u ^* v ^* ) The coefficient of determination of the linear regression line created by arranging u ^* and v ^* at the above optical densities in two-dimensional coordinates where the horizontal axis of the color space is u ^* and the vertical axis is v ^*. Determination) R ₂ is preferably 0.998 to 1.000. Furthermore, it is preferable that the v ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (v ^* / u ^* ) is 0.7 to 2.5.

(2) In addition, the optical density of the photothermographic dry imaging material is measured at 0.5, 1.0, 1.5 and the lowest optical density, next to the CIE 1976 (L ^* a ^* b ^* ) color space. The coefficient of determination (multiple determination) R ^{2 of} the linear regression line created by arranging a ^* and b ^* at each optical density in the two-dimensional coordinates where the axis is a ^* and the vertical axis is b ^* is from 0.998 to It is preferable that it is 1.000. Furthermore, it is preferable that the b ^* value of the intersection with the vertical axis of the linear regression line is −5 to 5 and the slope (b ^* / a ^* ) is 0.7 to 2.5.

An example of a method for creating the above-described linear regression line, that is, a method for measuring u ^* , v ^*, a ^* , and b ^{* in} the CIE 1976 color space will be described next.

A four-stage wedge sample including an unexposed portion and optical densities of 0.5, 1.0, and 1.5 is prepared using a heat development apparatus. Each wedge density part thus produced is measured with a spectrocolorimeter (Minolta Co., Ltd .: CM-3600d or the like), and u ^* , v ^* or a ^* , b ^* are calculated. The measurement conditions at that time are F7 light source as the light source, the viewing angle is 10 degrees, and the measurement is performed in the transmission measurement mode. Plot u ^* , v ^* or a ^* , b ^* measured on a graph with u ^* or a ^{* on} the horizontal axis and v ^* or b ^{* on the} vertical axis to obtain a linear regression line, and the coefficient of determination (multiple determination) Find R ² , intercept and slope.

  Next, a specific method for obtaining a linear regression line having the above characteristics will be described.

  In the present invention, adjustment of the addition amount of a compound or the like directly or indirectly involved in the development reaction process of a reducing agent (developer), silver halide grains, aliphatic silver carboxylate and the following toning agent, etc. Thus, the developed silver shape can be optimized to obtain a preferable color tone. For example, when the developed silver shape is dendritic, it becomes a bluish direction, and when it is a filament shape, it becomes a yellowish direction. That is, it can be adjusted in consideration of the tendency of the developed silver shape.

  Conventionally, phthalazinone or phthalazine and phthalic acids and phthalic anhydrides are generally used as toning agents. Examples of suitable toning agents include RD17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, and 4,021,249. Is disclosed.

  In the present invention, rapid processing is performed using a compact laser imager with a short cooling section length. However, there is a problem that the silver tone is greatly deviated from the neutral preferable tone as compared with the normal processing. In order to solve these problems, the above-described conventional color-adjusting agents are insufficient, and compounds (such as leuco dyes and coupler compounds) that form a dye image by developing color imagewise during heat development. Is required). As these compounds, a compound that develops color during thermal development and forms a dye image having a maximum absorption wavelength of 360 to 450 nm, or a color that forms color during thermal development and forms a dye image that has a maximum absorption wavelength of 600 to 700 nm or less. Although a compound is preferable, the case where both compounds are included is particularly preferable for obtaining a good silver tone. As these compounds, it is preferable to use couplers disclosed in JP-A No. 11-288057, European Patent No. 1,134,611A2, etc., or leuco dyes described in detail below.

(Leuco dye)
As described above, the silver salt photothermographic dry imaging material of the present invention can also be adjusted in color tone using a leuco dye. The leuco dye is preferably any colorless or slightly colored compound that is oxidized to a colored form when heated at a temperature of about 80-200 ° C. for about 0.5-30 seconds. Any leuco dye that can be oxidized by the body to form a pigment can be used. Compounds that are pH sensitive and can be oxidized to a colored state are useful.

  Representative leuco dyes suitable for use in the present invention are not particularly limited. For example, biphenol leuco dyes, phenol leuco dyes, indoaniline leuco dyes, acrylated azine leuco dyes, phenoxazine leuco dyes, phenodiazine leuco dyes. And phenothiazine leuco dye. Also useful are US Pat. Nos. 3,445,234, 3,846,136, 3,994,732, 4,021,249, 4,021,250, 4,022,617, 4,123,282, 4,368,247, 4,461,681, and JP-A-50-36110, 59-26831, These are leuco dyes disclosed in JP-A-5-204087, JP-A-11-231460, JP-A-2002-169249, and JP-A-2002-236334.

  In order to adjust to a predetermined color tone, it is preferable to use leuco dyes of various colors singly or in combination of a plurality of types. In addition, the use of highly active reducing agents for rapid processing changes the color tone (especially yellowishness) depending on the amount and ratio of use, or uses fine silver halide grains to develop developed silver. In order to prevent the image from becoming excessively reddish, especially in the high density part where the density is 2.0 or more, the use of a leuco dye that develops yellow and cyan colors is used in combination. It is preferable to adjust the amount.

  The color density is preferably adjusted appropriately in relation to the color tone of the developed silver itself. In the present invention, the color tone is adjusted so as to have an image in the above preferable color tone range by developing the color so as to have a reflection optical density of 0.01 to 0.05 or a transmission optical density of 0.005 to 0.50. preferable. In the present invention, the sum of the maximum densities at the maximum absorption wavelength of the dye image formed by the leuco dye is preferably 0.01 or more and 0.50 or less, more preferably 0.02 or more and 0.30 or less, and particularly preferably It is preferable that the color is developed so as to have 0.03 or more and 0.10 or less.

(Yellow coloring leuco dye)
As described above, the silver salt photothermographic dry imaging material of the present invention preferably adjusts the color tone using a leuco dye. In the present invention, a color image forming agent whose absorbance at 360 to 450 nm is increased by oxidation is particularly preferably used as a yellow color-forming leuco dye. These color image forming agents are particularly preferably color image forming agents represented by the following general formula (YA).

[Wherein R ₁₁ represents a substituted or unsubstituted alkyl group, R ₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an acylamino group, and R ₁₁ and R ₁₂ represent a 2-hydroxyphenylmethyl group. There is never. R ₁₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₁₄ represents a substituent that can be substituted on the benzene ring. ]
Hereinafter, the compound of the general formula (YA) will be described in detail.

In General Formula (YA), R ₁₁ represents a substituted or unsubstituted alkyl group. When R ₁₂ is a substituent other than a hydrogen atom, R ₁₁ represents an alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms and may have a substituent.

Specifically, methyl, ethyl, butyl, octyl, i-propyl, t-butyl, t-octyl, t-pentyl, sec-butyl, cyclohexyl, 1-methyl-cyclohexyl and the like are preferable, and steric rather than i-propyl. Are preferably large groups (i-propyl, i-nonyl, t-butyl, t-amyl, t-octyl, cyclohexyl, 1-methyl-cyclohexyl, adamantyl, etc.), among which secondary or tertiary alkyl Group is preferable, and tertiary alkyl groups such as t-butyl, t-octyl, and t-pentyl are particularly preferable. Examples of the substituent that R ₁₁ may have include a halogen atom, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamido group, an acyloxy group, an oxycarbonyl group, and a carbamoyl group. , Sulfamoyl group, sulfonyl group, phosphoryl group and the like.

R ₁₂ represents a hydrogen atom, a substituted or unsubstituted alkyl group or an acylamino group. The alkyl group represented by R ₁₂ is preferably an alkyl group having 1 to 30 carbon atoms, and the acylamino group is preferably an acylamino group having 1 to 30 carbon atoms. Among these, the description of the alkyl group is the same as R ₁₁ described above.

The acylamino group represented by R ₁₂ may be unsubstituted or substituted, and specific examples include an acetylamino group, an alkoxyacetylamino group, and an aryloxyacetylamino group. R ₁₂ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include methyl, i-propyl, and t-butyl. R ₁₁ and R ₁₂ are not 2-hydroxyphenylmethyl groups.

R ₁₃ represents a hydrogen atom or a substituted or unsubstituted alkyl group. The alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, and the description of the alkyl group is the same as that for R ₁₁ . R ₁₃ is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 24 carbon atoms, and specific examples include methyl, i-propyl, t-butyl and the like. Further, it is preferable either R _12, R ₁₃ is a hydrogen atom.

R ₁₄ represents a group substitutable on the benzene ring, and is, for example, the same group as described for the substituent R ₄ in the general formula (RD1). R ₁₄ is preferably a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms or an oxycarbonyl group having 2 to 30 carbon atoms, and more preferably an alkyl group having 1 to 24 carbon atoms. Examples of the substituent of the alkyl group include an aryl group, an amino group, an alkoxy group, an oxycarbonyl group, an acylamino group, an acyloxy group, an imide group, and a ureido group, and more preferable examples include an aryl group, an amino group, an oxycarbonyl group, and an alkoxy group. preferable. These alkyl group substituents may be further substituted with these substituents.

  Next, among the compounds represented by the general formula (YA), the bisphenol compound represented by the following general formula (YB), which is particularly preferably used in the present invention, will be described.

[Wherein, Z represents —S— or —C (R ₂₁ ) (R ₂₁ ′) —, and R ₂₁ and R ₂₁ ′ each represents a hydrogen atom or a substituent. ]
Examples of the substituent represented by R ₂₁ and R ₂₁ ′ include the same groups as the substituents exemplified in the description of R _{1 in} the general formula (RD1). R ₂₁ and R ₂₁ ′ are preferably a hydrogen atom or an alkyl group.

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ each represent a substituent, and examples of the substituent include the same groups as those described for R ₂ and R ₃ in the general formula (RD1).

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ are preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, but an alkyl group is more preferable. Examples of the substituent on the alkyl group include the same groups as those described in the description of the substituent in the general formula (RD1).

R ₂₂ , R ₂₃ , R ₂₂ ′ and R ₂₃ ′ are more preferably tertiary alkyl groups such as t-butyl, t-pentyl, t-octyl and 1-methyl-cyclohexyl.

R ₂₄ and R ₂₄ ′ each represent a hydrogen atom or a substituent, and examples of the substituent include the same groups as the substituents described in the description of R ₄ in formula (RD1).

  Examples of the compounds represented by the general formulas (YA) and (YB) include compounds (II-1) to (II-40) described in paragraphs “0032” to “0038” of JP-A No. 2002-169249, Examples thereof include compounds (ITS-1) to (ITS-12) described in paragraph “0026” of EP 1,211,093.

  Although the specific example of the bisphenol compound represented by general formula (YA) and (YB) below is shown, this invention is not limited to these.

  The addition amount of the compound of the general formula (YA) (including hindered phenol compounds and compounds of the general formula (YB)) is usually 0.00001 to 0.01 mol, preferably 0. 0005 to 0.01 mol, more preferably 0.001 to 0.008 mol.

  Moreover, it is preferable that the addition amount ratio with respect to the sum total of the reducing agent represented by general formula (RD1) and (RD2) of yellow coloring leuco dye is 0.001-0.2 in molar ratio, 0.005 More preferably, it is -0.1.

(Cyan coloring leuco dye)
The silver salt photothermographic dry imaging material of the present invention preferably adjusts the color tone by using a cyan coloring leuco dye in addition to the yellow coloring leuco dye.

  The cyan chromophoric leuco dye is preferably any colorless or slightly colored compound that is oxidized to a colored form when heated at a temperature of about 80-200 ° C. for about 0.5-30 seconds. Any leuco dye that forms a pigment by oxidation with an oxidant of the agent can be used. Compounds that are pH sensitive and can be oxidized to a colored state are useful.

  In the present invention, a color image forming agent whose absorbance at 600 to 700 nm is increased by oxidation is particularly preferably used as a cyan color-forming leuco dye. Examples of these compounds include compounds of general formula (I) to general formula (IV) described in JP-A-59-206831 (particularly compounds having λmax in the range of 600 to 700 nm) and JP-A-5-204087. Specifically, the compounds of (1) to (18) described in paragraphs “0032” to “0037”) and compounds of general formulas 4 to 7 in JP-A No. 11-231460 (specifically, paragraph “0105”). No. 1 to No. 79 compounds).

  The cyan color-forming leuco dye preferably used in the present invention is a compound represented by the following general formula (CLA) or general formula (CLB). The color image forming agent represented by the general formula (CLB) is particularly preferable in that it has high color development efficiency, can be adjusted in color even when added in a small amount, and is excellent in image storage stability.

  The compounds of general formula (CLA) and general formula (CLB) that are preferably used below will be described in detail.

  (Compound represented by general formula (CLA))

[Wherein R ₃₁ and R ₃₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, —NHCO—R ₃₀ group (R ₃₀ is an alkyl group, aryl group, heterocyclic group) Or R ₃₁ and R ₃₂ are groups that are linked to each other to form an aliphatic hydrocarbon ring, an aromatic hydrocarbon ring, or a heterocyclic ring. A ₃ represents a —NHCO— group, a —CONH— group or a —NHCONH— group, and R ₃₃ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group. W ₃ represents a hydrogen atom or —CONH—R ₃₅ group, —CO—R ₃₅ group or —CO—O—R ₃₅ group (R ₃₅ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group). R ₃₄ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, alkenyl group, alkoxy group, carbamoyl group, or nitrile group. R ₃₆ represents —CONH—R ₃₇ group, —CO—R ₃₇ group or —CO—O—R ₃₇ group (R ₃₇ represents a substituted or unsubstituted alkyl group, aryl group or heterocyclic group) X ₃ Represents a substituted or unsubstituted aryl group or heterocyclic group. ]
In the general formula (CLA), examples of the halogen atom represented by R ₃₁ and R ₃₂ include a fluorine atom, a bromine atom, and a chlorine atom, and the alkyl group includes an alkyl group having up to 20 carbon atoms (for example, Methyl group, ethyl group, butyl group, dodecyl group, etc.). Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (for example, vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl-2-ethyl group). A propenyl group, a 3-butenyl group, a 1-methyl-3-propenyl group, a 3-pentenyl group, a 1-methyl-3-butenyl group, and the like. As the alkoxy group, an alkoxy group having up to 20 carbon atoms (for example, methoxy) Group, ethoxy and the like). Examples of the alkyl group represented by R ₃₀ in the —NHCO—R ₃₀ group include alkyl groups having up to 20 carbon atoms (for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, etc.), and an aryl group. Examples thereof include a group having 6 to 20 carbon atoms such as a phenyl group and a naphthyl group, and examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group. The alkyl group represented by R ₃₃ is preferably an alkyl group having up to 20 carbon atoms, and examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group, and the aryl group preferably has 6 to 20 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

In the —CONH—R ₃₅ group, —CO—R ₃₅ group or —CO—O—R ₃₅ group represented by W ₃ , the alkyl group represented by R ₃₅ is preferably an alkyl group having up to 20 carbon atoms. Examples thereof include a methyl group, an ethyl group, a butyl group, and a dodecyl group. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and examples thereof include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

Examples of the halogen atom represented by R ₃₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group include a chain or cyclic alkyl group such as a methyl group, a butyl group, and dodecyl. Group, cyclohexyl group and the like. Examples of the alkenyl group include alkenyl groups having up to 20 carbon atoms (for example, vinyl group, allyl group, butenyl group, hexenyl group, hexadienyl group, ethenyl-2-propenyl group, 3-butenyl group, 1-methyl-3-propenyl group, 3-pentenyl group, 1-methyl-3-butenyl, etc.), and alkoxy groups include, for example, methoxy group, butoxy group, tetradecyloxy group, etc., and carbamoyl Examples of the group include a diethylcarbamoyl group and a phenylcarbamoyl group. Nitrile groups are also preferred. Among these, a hydrogen atom and an alkyl group are more preferable. R ₃₃ and R ₃₄ may be connected to each other to form a ring structure.

  The above groups can further have a single substituent or multiple substituents. Typical substituents include halogen atoms (eg, fluorine atom, chlorine atom, bromine atom), alkyl groups (eg, methyl group, ethyl group, propyl group, butyl group, dodecyl group), hydroxyl group, cyano group , Nitro group, alkoxy group (for example, methoxy group, ethoxy group, etc.), alkylsulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, etc.), arylsulfonamide group (for example, phenylsulfonamide group, naphthylsulfone) Amide group etc.), alkylsulfamoyl group (eg butylsulfamoyl group etc.), arylsulfamoyl (eg phenylsulfamoyl group etc.), alkyloxycarbonyl group (eg methoxycarbonyl group etc.), aryl Oxycarbonyl group (for example, phenyloxycarbonyl group, etc.) , Amino sulfonamido group, an acylamino group, a carbamoyl group, a sulfonyl group, a sulfinyl group, a sulfoxy group, a sulfo group, an aryloxy group, an alkoxy group, an alkylcarbonyl group, arylcarbonyl group, and an amino carbonyl group.

R ₃₀ or R ₃₅ is preferably a phenyl group, and more preferably a phenyl group having a plurality of halogen atoms and cyano groups as substituents.

-CONH-R ₃₇ group represented by R _36, in -CO-R ₃₇ group, or -CO-O-R ₃₇ group, the alkyl group represented by R ₃₇ is preferably an alkyl group having up to 20 carbon atoms Yes, for example, a methyl group, an ethyl group, a butyl group, a dodecyl group, and the like. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, an imidazole group, a pyrazole group, and a pyrrole group.

As the substituent that the group represented by R ₃₇ can have, the same substituents as those described in the description of R _{31 to} R _{34 in} formula (CLA) can be used.

Examples of the aryl group represented by X ₃ include aryl groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, and a thienyl group. Examples of the heterocyclic group include a thiophene group, a furan group, and an imidazole group. Group, pyrazole group, pyrrole group and the like.

Examples of the substituent that the group represented by X ₃ can have include the same substituents as those described in the description of R _{31 to} R _{34 in} formula (CLA). The group represented by X ₃ is preferably an aryl group or heterocyclic group having an alkylamino group (such as a diethylamino group) at the para position.

  These groups may include photographically useful groups.

  Specific examples of the cyan color forming leuco dye (CLA) are shown below, but the cyan color forming leuco dye used in the present invention is not limited thereto.

  (Compound represented by general formula (CLB))

[Wherein R ₄₁ , R ₄₂ , R _4a and R _4b each independently represents a hydrogen atom, aliphatic group, aromatic group, alkoxy group, aryloxy group, acylamino group, sulfonamido group, carbamoyl group, halogen atom. To express. R ₄₃ represents a hydrogen atom, an aliphatic group, an aromatic group, an acyl group, an alkoxycarbonyl group, an aryloxycarboquinyl group, a carbamoyl group, a sulfamoyl group, or a sulfonyl group. X ₄₁ and X ₄₂ represent a substitutable group on the benzene ring. m41 and m42 represent an integer of 0 to 5. When there are a plurality of X ₄₁ and X ₄₂ , each X ₄₁ and X ₄₂ may be the same or different. ]
In the general formula (CLB), specific examples of the aliphatic group represented by R ₄₁ , R ₄₂ , R _4a, and R _4b include hydrocarbon groups such as an alkyl group, an alkenyl group, and an alkynyl group. These hydrocarbon groups preferably have 1 to 25 carbon atoms, and more preferably 1 to 20 carbon atoms. Examples of the alkyl group having 1 to 25 carbon atoms include methyl, ethyl, propyl, i-propyl, t-butyl, pentyl, hexyl, cyclohexyl, etc., as cycloalkyl groups (cyclohexyl, cyclopentyl groups, etc.), and as alkenyl groups ( Ethenyl-2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl and the like) and alkynyl groups (ethynyl, 1propynyl, propargyl and the like).

Specific examples of the aromatic group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include aryl groups (phenyl, naphthyl, etc.), heterocyclic groups (pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl). , Pyrimidinyl, pyridazinyl, selenazolyl, sriphoranyl, piperidinyl, pyrazolyl, tetrazolyl and the like.

Specific examples of the alkoxy group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include methoxy group, ethoxy group, isopropyloxy group, tert-butoxy group and the like.

Specific examples of the aryloxy group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include a phenoxy group and a naphthyloxy group.

Examples of the acylamino group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include an acetylamino group and a benzoylamino group.

Specific examples of the sulfonamide group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include a methanesulfonamide group, a butanesulfonamide group, an octanesulfonamide group, a benzenesulfonamide group, and the like.

Examples of the carbamoyl group represented by R ₄₁ , R ₄₂ , R _4a and R _4b include an aminocarbonyl group, a methylaminocarbonyl group, a dimethylaminocarbonyl group, a propylaminocarbonyl group, a pentylaminocarbonyl group, and a cyclohexylaminocarbonyl group. , Phenylaminocarbonyl group, 2-pyridylaminocarbonyl group and the like.

Examples of the halogen atom represented by R ₄₁ , R ₄₂ , R _4a and R _4b are chlorine, bromine and iodine.

R ₄₁ and R ₄₂ are preferably an aliphatic group, an alkoxy group, an aryloxy group, more preferably an alkyl group or an alkoxy group, still more preferably a secondary or tertiary alkyl group or an alkoxy group.

R _4a and R _4b are preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom.

Examples of the aliphatic group, aromatic group, alkoxy group and aryloxy group represented by R ₄₃ include those of the aliphatic group, aromatic group, alkoxy group and aryloxy group represented by R ₄₁ and R ₄₂ . The example given as a specific example is given.

Specific examples of the acyl group represented by R ₄₃ include an acetyl group, a propionyl group, a butanoyl group, a hexanoyl group, a cyclohexanoyl group, a benzoyl group, and a pyridinoyl group.

Specific examples of the alkoxycarbonyl group represented by R ₄₃ include a methoxycarbonyl group, an ethoxycarbonyl group, and a tert-butoxycarbonyl group.

Specific examples of the aryloxycarboquinyl group represented by R ₄₃ include a phenoxycarbonyl group.

Examples of the carbamoyl group represented by R ₄₃ include an aminocarbonyl group, a methylaminocarbonyl group, a dimethylaminocarbonyl group, a propylaminocarbonyl group, a pentylaminocarbonyl group, a cyclohexylaminocarbonyl group, a phenylaminocarbonyl group, and 2-pyridylamino. A carbonyl group etc. are mentioned.

Examples of the sulfamoyl group represented by R ₄₃ include methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl and the like.

Examples of the sulfonyl group represented by R ₄₃ include a methylsulfonyl group, a butylsulfonyl group, and an octylsulfonyl group.

R ₄₃ is preferably a hydrogen atom, an alkyl group, or an acyl group, more preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an acyl group.

Specific examples of the group that can be substituted on the benzene ring represented by X ₄₁ and X ₄₂ include alkyl groups having 1 to 25 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, Pentyl group, hexyl group, cyclohexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, etc.), alkenyl group (vinyl, allyl, butenyl, hexenyl, hexadienyl, ethenyl-2-propenyl, 3-butenyl, 1-methyl- 3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, etc.), alkynyl group (ethynyl, propargyl group, etc.), glycidyl group, acrylate group, methacrylate group, aryl group (phenyl group etc.), aryl group (phenyl, Naphthyl group, etc.), heterocyclic group (pyridyl group, thiazolyl group, oxazolyl group, imida Ryl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, triphoranyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.), halogen atom (chlorine 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, etc.), alkoxycarbonyl group (methyloxycarbonyl group) , Ethyloxycarbonyl group, butyloxycarbonyl group, etc.), aryloxycarbonyl group (phenyloxycarbonyl group, etc.), sulfonamide group (methanesulfonamide group, ethanesulfonamide group, butanesulfonamide group, hexane) Sulfonamide group, cyclohexanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl 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, etc.), acyl group (acetyl group, propionyl group, Butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), carbamoyl group (aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl) Rubonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, phenylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), amide group (acetamide group, propionamide group, butanamide group, hexanamide group, benzamide group) Etc.), sulfonyl group (methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, phenylsulfonyl group, 2-pyridylsulfonyl group, etc.), sulfonamide group (for example, methylsulfonamide group, octylsulfonamide group, Phenylsulfonamide group, naphthylsulfonamide group, etc.), amino group (amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, anilino group, 2-pyri Arylamino group), a cyano group, a nitro group, a sulfo group, a carboxyl group, a hydroxyl group, can be exemplified Okizamoiru group. Further, these groups may be further substituted with these groups.

X ₄₁ and X ₄₂ are preferably an alkoxy group, an aryloxy group, a carbamoyl group, an amide group, a sulfonamide group, an amino group, more preferably an alkoxy group or an amino group.

In the above general formula (CLB), R _4a and R _4b are hydrogen atoms, and X ₄₁ and X ₄₂ are each an aliphatic group, aromatic group, amino group, alkoxy group, aryloxy group or dialkylamide at the p-position. Those substituted with a group are preferred.

  The compound represented by the general formula (CLB) can be easily synthesized by a conventionally known method, for example, the method described in Japanese Patent Publication No. 7-45477.

  Next, although the specific example of a compound of general formula (CLB) is shown, this invention is not limited to these.

  The addition amount of the cyan coloring leuco dye is usually 0.00001 to 0.05 mol / Ag1 mol, preferably 0.0005 to 0.02 mol / Ag1 mol, more preferably 0.001 to 0.01 mol. / Ag1 mol. The addition ratio of the cyan coloring leuco dye to the sum of the reducing agents represented by the general formulas (RD1) and (RD2) is preferably 0.001 to 0.2 in terms of molar ratio, and 0.005. More preferably, it is -0.1.

  In the silver salt photothermographic dry imaging material of the present invention, the sum of the maximum densities at the maximum absorption wavelength of a dye image formed with a cyan leuco dye is preferably 0.01 or more and 0.50 or less, more preferably 0.02. It is preferable to develop the color so that it has a value of 0.30 or less, particularly preferably 0.03 or more and 0.10 or less.

  In the present invention, a subtle color tone can be adjusted by using a magenta color developing leuco dye or a yellow color developing leuco dye in addition to the cyan color developing leuco dye.

  As a method for adding the compounds represented by the general formulas (YA) and (YB) and the cyan color-forming leuco dye, they can be added in the same manner as the method for adding the reducing agent represented by the general formula (RD1). , Solution form, emulsified dispersion form, solid fine particle dispersion form, etc. may be contained in the coating solution by any method, and may be contained in the photosensitive material.

  The compounds of the general formulas (RD1), (RD2), general formulas (YA) and (YB) and the cyan color-forming leuco dye are preferably contained in a photosensitive layer (image forming layer) containing an organic silver salt. One may be contained in the photosensitive layer and the other may be contained in the non-photosensitive layer adjacent to the photosensitive layer, or both may be contained in the non-photosensitive layer. When the photosensitive layer is composed of a plurality of layers, they may be contained in separate layers.

(Crosslinking agent)
The photosensitive layer according to the present invention may contain a cross-linking agent capable of connecting the binders according to the present invention by cross-linking. By using a crosslinking agent for the binder, it is known that filming is improved and development unevenness is reduced, but there is also an effect of suppressing fogging during storage and suppressing generation of printout silver after development. is there.

  Examples of the crosslinking agent to be used include various crosslinking agents conventionally used for photographic light-sensitive materials, for example, aldehyde-based, epoxy-based, ethyleneimine-based, vinylsulfone-based, sulfone described in JP-A-50-96216. Acid ester-based, acryloyl-based, carbodiimide-based, and silane compound-based crosslinking agents are used, and the following isocyanate-based, silane compound-based, epoxy-based compounds, and acid anhydrides are preferable.

  Isocyanate-based crosslinking agents are isocyanates having at least two isocyanate groups and adducts thereof (adducts). More specifically, aliphatic diisocyanates, aliphatic diisocyanates having a cyclic group, benzene Diisocyanates, naphthalene diisocyanates, biphenyl isocyanates, diphenylmethane diisocyanates, triphenylmethane diisocyanates, triisocyanates, tetraisocyanates, adducts of these isocyanates and divalent or trivalent polyalcohols with these isocyanates Adducts and the like. As specific examples, isocyanate compounds described on pages 10 to 12 of JP-A-56-5535 can be used.

  In addition, the adduct of isocyanate and polyalcohol has particularly high ability to improve interlayer adhesion and prevent layer peeling, image shift and bubble generation. Such isocyanate may be placed in any part of the photothermographic material. For example, in the support (especially when the support is paper, it can be included in the size composition) photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc. It can be added to any layer and can be added to one or more of these layers.

  As the thioisocyanate-based crosslinking agent that can be used in the present invention, compounds having a thioisocyanate structure corresponding to the above-mentioned isocyanates are also useful.

  The amount of the crosslinking agent used is usually in the range of 0.001 to 2 mol, preferably 0.005 to 0.5 mol, with respect to 1 mol of silver.

  The isocyanate compound and thioisocyanate compound that can be contained in the present invention are preferably compounds that function as the above-mentioned crosslinking agent, but a good result can be obtained even if the compound has only one functional group.

  Examples of the silane compound include compounds represented by general formulas (1) to (3) disclosed in JP-A No. 2001-264930.

  Moreover, as an epoxy compound which can be used as a crosslinking agent, what is necessary is just to have one or more epoxy groups, and there is no restriction | limiting in the number of epoxy groups, molecular weight, and others. The epoxy group is preferably contained in the molecule as a glycidyl group via an ether bond or an imino bond. The epoxy compound may be any of a monomer, an oligomer, a polymer, etc., and the number of epoxy groups present in the molecule is usually about 1 to 10, preferably 2 to 4. When the epoxy compound is a polymer, it may be either a homopolymer or a copolymer, and the number average molecular weight Mn is particularly preferably in the range of about 2,000 to 20,000.

  The acid anhydride used in the present invention is a compound having at least one acid anhydride group represented by the following structural formula. The number of acid anhydride groups, molecular weight, and the like are not particularly limited as long as they have one or more acid anhydride groups.

-CO-O-CO-
Said epoxy compound and acid anhydride may use only 1 type, or may use 2 or more types together. The addition amount is not particularly limited, but is preferably in the range of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol / m ² , more preferably in the range of 1 × 10 ⁻⁵ to 1 × 10 ⁻³ mol / m ² . It is. This epoxy compound or acid anhydride can be added to any layer on the photosensitive layer side of the support, such as the photosensitive layer, surface protective layer, intermediate layer, antihalation layer, subbing layer, etc., and one of these layers Or it can add to two or more layers.

(Silver saving agent)
The photosensitive layer or the non-photosensitive layer according to the present invention may contain a silver saving agent. As used herein, the silver saving agent refers to a compound that can reduce the amount of silver necessary to obtain a certain silver image density.

  Although various mechanisms for the function of reducing the required silver amount are conceivable, a compound having a function of improving the covering power of developed silver is preferred. Here, the covering power of developed silver refers to the optical density per unit amount of silver. This silver saving agent can be present in the photosensitive layer, the non-photosensitive layer, or both. Preferred examples of the silver saving agent include hydrazine derivative compounds, vinyl compounds, phenol derivatives, naphthol derivatives, quaternary onium compounds, and silane compounds.

  Specific examples of the hydrazine derivative include compounds H-1 to H-29 described in US Pat. No. 5,545,505, columns 11 to 20, US Pat. No. 5,464,738, columns 9 to 11. 1 to 12 described in JP-A-2001-27790, compounds H-1-1 to H-1-28 described in paragraphs “0042” to “0052”, and H-2-1 to H-2- 9, H-3-1 to H-3-12, H-4-1 to H-4-21, H-5-1 to H-5-5.

  Specific examples of the vinyl compound include compounds CN-01 to CN-13 described in columns 13 to 14 of US Pat. No. 5,545,515 and column 10 of US Pat. No. 5,635,339. Compounds HET-01 to HET-02 described in US Pat. No. 5,654,130, columns MA-10 to compounds MA-01 to MA-07, US Pat. No. 5,705,324 Compounds IS-01 to IS-04 described in columns 9 to 10 of the specification, and compounds 1-1 to 218-2 described in paragraphs “0043” to “0088” of JP-A-2001-125224.

  Specific examples of the phenol derivative and the naphthol derivative include compounds A-1 to A-89 described in paragraphs “0075” to “0078” of JP 2000-267222 A, and paragraph “0025” of JP 2003-66558 A. ”To“ 0045 ”. Examples thereof include compounds A-1 to A-258.

  Specific examples of the quaternary onium compound include triphenyltetrazolium.

  Specific examples of the silane compound include alkoxysilane compounds having two or more primary or secondary amino groups as shown in compounds A1 to A33 described in paragraphs “0027” to “0029” of JP-A No. 2003-5324 or The salt is mentioned.

The amount of the silver saving agent added is in the range of 1 × 10 ⁻⁵ to 1 mol, preferably 1 × 10 ^{−4 to} 5 × 10 ⁻¹ mol, per mol of the organic silver salt.

  Particularly preferred silver saving agents of the present invention are compounds represented by the following general formulas (SE1) and (SE2).

General formula (SE1)
Q ₁ -NHNH-Q ₂
[In the formula, Q ₁ represents an aromatic group or a heterocyclic group bonded to —NHNH—Q ₂ at a carbon atom, Q ₂ represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, Or represents a sulfamoyl group. ]
In the general formula (SE1), the aromatic group or heterocyclic group represented by Q ₁ is preferably a 5- to 7-membered unsaturated ring. Preferred examples include benzene ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, 1,2,4-triazine ring, 1,3,5-triazine ring, pyrrole ring, imidazole ring, pyrazole ring, 1,2 , 3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,3,4 -Oxadiazole ring, 1,2,4-oxadiazole ring, 1,2,5-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, thiophene ring, etc. are preferable, and these Also preferred are fused rings in which the rings are fused together.

  These rings may have a substituent, and when they have two or more substituents, these substituents may be the same or different. Examples of substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, arylsulfonamido groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, carbamoyl groups, sulfamoyl groups, cyano Groups, alkylsulfonyl groups, arylsulfonyl groups, alkoxycarbonyl groups, aryloxycarbonyl groups, and acyl groups. When these substituents are substitutable groups, they may further have substituents. Examples of preferred substituents include halogen atoms, alkyl groups, aryl groups, carbonamido groups, alkylsulfonamido groups, aryls. Sulfonamide group, alkoxy group, aryloxy group, alkylthio group, arylthio group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, and acyloxy group Can be mentioned.

The carbamoyl group represented by Q ₂ is preferably a carbamoyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms. For example, unsubstituted carbamoyl, methylcarbamoyl, N-ethylcarbamoyl, N-propylcarbamoyl N-sec-butylcarbamoyl, N-octylcarbamoyl, N-cyclohexylcarbamoyl, N-tert-butylcarbamoyl, N-dodecylcarbamoyl, N- (3-dodecyloxypropyl) carbamoyl, N-octadecylcarbamoyl, N- {3 -(2,4-tert-pentylphenoxy) propyl} carbamoyl, N- (2-hexyldecyl) carbamoyl, N-phenylcarbamoyl, N- (4-dodecyloxyphenyl) carbamoyl, N- (2-chloro-5 Dodecyloxycarbo Butylphenyl) carbamoyl, N- naphthylcarbamoyl, N-3- pyridylcarbamoyl include N- benzylcarbamoyl.

The acyl group represented by Q ₂ is preferably an acyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2 -Hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, 2-hydroxymethylbenzoyl. The alkoxycarbonyl group represented by Q2 is preferably an alkoxycarbonyl group having 2 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, dodecyl. Examples include oxycarbonyl and benzyloxycarbonyl.

The aryloxycarbonyl group represented by Q ₂ is preferably an aryloxycarbonyl group having 7 to 50 carbon atoms, more preferably 7 to 40 carbon atoms, such as phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxy Examples thereof include methylphenoxycarbonyl and 4-dodecyloxyphenoxycarbonyl. The sulfonyl group represented by Q2 is preferably a sulfonyl group having 1 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, 3-dodecyl. Examples include oxypropylsulfonyl, 2-octyloxy-5-tert-octylphenylsulfonyl, and 4-dodecyloxyphenylsulfonyl.

The sulfamoyl group represented by Q ₂ is preferably a sulfamoyl group having 0 to 50 carbon atoms, more preferably 6 to 40 carbon atoms, such as an unsubstituted sulfamoyl group, an N-ethylsulfamoyl group, N- (2- Ethylhexyl) sulfamoyl, N-decylsulfamoyl, N-hexadecylsulfamoyl, N- {3- (2-ethylhexyloxy) propyl} sulfamoyl, N- (2-chloro-5-dodecyloxycarbonylphenyl) sulfamoyl, N- (2-tetradecyloxyphenyl) sulfamoyl is mentioned. The group represented by Q ₂ may further have the group exemplified as the substituent of the 5- to 7-membered unsaturated ring represented by Q ₁ at a substitutable position. When it has two or more substituents, these substituents may be the same or different.

Next, a preferable range of the compound represented by formula (SE1) is described. Q ₁ is preferably a 5- to 6-membered unsaturated ring, such as a benzene ring, pyrimidine ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, 1,3,4-thiadiazole ring. 1,2,4-thiadiazole ring, 1,3,4-oxadiazole ring, 1,2,4-oxadiazole ring, thiazole ring, oxazole ring, isothiazole ring, isoxazole ring, and these rings Is more preferably a ring fused with a benzene ring or an unsaturated heterocycle. Q ₂ is preferably a carbamoyl group, particularly preferably a carbamoyl group having a hydrogen atom on a nitrogen atom.

In the general formula (SE2), R ₁ represents an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, or a carbamoyl group. R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, or a carbonate group. R ₃ and R ₄ each represents a group that can be substituted on the benzene ring mentioned in the example of the substituent of formula (SE1). R ₃ and R ₄ may be connected to each other to form a condensed ring.

R ₁ is preferably an alkyl group having 1 to 20 carbon atoms (for example, a methyl group, an ethyl group, an isopropyl group, a butyl group, a tert-octyl group, a cyclohexyl group, etc.), an acylamino group (for example, an acetylamino group, a benzoylamino group, Methylureido group, 4-cyanophenylureido group, etc.), carbamoyl group (n-butylcarbamoyl group, N, N-diethylcarbamoyl group, phenylcarbamoyl group, 2-chlorophenylcarbamoyl group, 2,4-dichlorophenylcarbamoyl group, etc.) An acylamino group (including a ureido group and a urethane group) is more preferable. R ₂ is preferably a halogen atom (more preferably a chlorine atom or a bromine atom), an alkoxy group (for example, a methoxy group, a butoxy group, an n-hexyloxy group, an n-decyloxy group, a cyclohexyloxy group, a benzyloxy group, etc.), aryl An oxy group (phenoxy group, naphthoxy group, etc.);

R ₃ is preferably a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, and most preferably a halogen atom. R ₄ is preferably a hydrogen atom, an alkyl group or an acylamino group, more preferably an alkyl group or an acylamino group. Examples of these preferable substituents are the same as those for R ₁ . When R ₄ is an acylamino group, R ₄ is preferably linked to R ₃ to form a carbostyryl ring.

In the general formula (SE2), when R ₃ and R ₄ are connected to each other to form a condensed ring, a naphthalene ring is particularly preferable as the condensed ring. The same substituent as the example of the substituent mentioned in the general formula (SE1) may be bonded to the naphthalene ring. When general formula (SE2) is a naphthol compound, R ₁ is preferably a carbamoyl group. Of these, a benzoyl group is particularly preferable. R ₂ is preferably an alkoxy group or an aryloxy group, and particularly preferably an alkoxy group.

  Hereafter, the preferable specific example of the silver saving agent of this invention is given. The present invention is not limited to these.

(Thermal solvent)
The silver salt photothermographic dry imaging material of the present invention preferably contains a thermal solvent. Here, the thermal solvent is defined as a material capable of lowering the heat development temperature by 1 ° C. or more as compared with the silver salt photothermographic dry imaging material containing no thermal solvent with respect to the photothermographic dry imaging material containing the thermal solvent. To do. More preferably, the material can lower the heat development temperature by 2 ° C. or more, and particularly preferably the material that can lower the temperature by 3 ° C. or more. For example, with respect to the photothermographic dry imaging material A containing a thermosolvent, when the photothermographic dry imaging material A from the photothermographic dry imaging material A is B, the photothermographic dry imaging material B is exposed and thermally developed. When the thermal development temperature for obtaining the density obtained by processing at a temperature of 120 ° C. and a thermal development time of 20 seconds with the photothermographic dry imaging material A at the same exposure amount and thermal development time is 119 ° C. or less, To do.

  The thermal solvent has a polar group as a substituent and is preferably represented by the general formula (TS), but is not limited thereto.

General formula (TS)
(Y) _n Z
In General Formula (TS), Y represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group. Z represents a group selected from a hydroxy group, carboxy group, amino group, amide group, sulfonamide group, phosphoric acid amide group, cyano group, imide, ureido, sulfoxide, sulfone, phosphine, phosphine oxide or nitrogen-containing heterocyclic group. . n represents an integer of 1 to 3, which is 1 when Z is a monovalent group, and is the same as the valence of Z when Z is a divalent or higher group. When n is 2 or more, the plurality of Y may be the same or different.

  Y may further have a substituent, and may have a group represented by Z as a substituent. Y will be described in more detail. In general formula (TS), Y is a linear, branched or cyclic alkyl group (preferably having 1 to 40 carbon atoms, more preferably 1 to 30 carbon atoms, particularly preferably 1 to 25 carbon atoms such as methyl, ethyl, n -Propyl, iso-propyl, sec-butyl, t-butyl, t-octyl, n-amyl, t-amyl, n-dodecyl, n-tridecyl, octadecyl, icosyl, docosyl, cyclopentyl, cyclohexyl and the like. An alkenyl group (preferably having 2 to 40 carbon atoms, more preferably 2 to 30 carbon atoms, particularly preferably 2 to 25 carbon atoms such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an aryl group (Preferably having 6 to 40 carbon atoms, more preferably 6 to 30 carbon atoms, particularly preferably 6 to 25 carbon atoms such as phenyl and p-methyl. Phenyl, naphthyl, etc.), heterocyclic groups (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms such as pyridyl, pyrazyl, imidazolyl, pyrrolidyl, etc. Represents.). These substituents may be further substituted with other substituents. These substituents may be bonded to each other to form a ring.

  Y may further have a substituent, and examples of the substituent include those described in “0015” of JP-A No. 2004-21068. The reason why development activity is achieved by using a thermal solvent is that the thermal solvent melts near the development temperature, so that it is compatible with substances involved in development, and a reaction at a lower temperature than when no thermal solvent is added. This is thought to be possible. Since heat development is a reduction reaction involving a carboxylic acid having a relatively high polarity or a silver ion transporter, it is preferable to form a reaction field having an appropriate polarity with a thermal solvent having a polar group. .

  The melting point of the thermal solvent preferably used in the present invention is 50 ° C. or more and 200 ° C. or less, more preferably 60 ° C. or more and 150 ° C. or less. In particular, in a photothermographic material that emphasizes stability to an external environment such as image storage stability, which is the object of the present invention, a heat solvent having a melting point of 100 ° C. or higher and 150 ° C. or lower is preferable.

  Specific examples of the thermal solvent include compounds described in “0017” of JP-A No. 2004-21068, compounds described in “0027” of US 2002/0025498, MF-1 to MF-3, and MF6. MF-7, MF-9 to MF-12, MF-15 to MF-22.

Preferably the added amount of thermal solvent is 0.01~5.0g / m ² in the present invention, more preferably 0.05~2.5g / m ^2, more preferably 0.1~1.5g / M ² . The thermal solvent is preferably contained in the photosensitive layer. Moreover, although the said thermal solvent may be used independently, you may use it in combination of 2 or more type. In the present invention, the thermal solvent may be contained in the coating solution by any method such as a solution form, an emulsified dispersion form, or a solid fine particle dispersion form, and may be contained in the photosensitive material.

  Well-known emulsifying dispersion methods include dissolving oil using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate or diethyl phthalate, or an auxiliary solvent such as ethyl acetate or cyclohexanone, and mechanically dispersing the emulsified dispersion. The method of producing is mentioned.

  The solid fine particle dispersion method is a method of preparing a solid dispersion by dispersing a hot solvent powder in a suitable solvent such as water by ball mill, colloid mill, vibration ball mill, sand mill, jet mill, roller mill or ultrasonic waves. Is mentioned. In this case, a protective colloid (for example, polyvinyl alcohol) or a surfactant (for example, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of three isopropyl groups having different substitution positions)) may be used. Good. In the mills, beads such as zirconia are usually used as a dispersion medium, and Zr and the like eluted from these beads may be mixed in the dispersion. Although it depends on the dispersion conditions, it is usually in the range of 1 ppm to 1000 ppm. If the Zr content in the light-sensitive material is 0.5 mg or less per 1 g of silver, there is no practical problem. The aqueous dispersion preferably contains a preservative (for example, benzoisothiazolinone sodium salt).

(Anti-fogging and image stabilizer)
In any constituent layer of the silver salt photothermographic dry imaging material of the present invention, an antifoggant for preventing fogging during storage before heat development, and an image deterioration after heat development are prevented. It is preferable to contain an image stabilizer.

  The antifogging and image stabilizer that can be used in the silver salt photothermographic dry imaging material of the present invention will be described.

As reducing agents according to the present invention, reducing agents having protons such as bisphenols and sulfonamidophenols are mainly used, so that these hydrogens are stabilized, the reducing agents are deactivated, and silver ions are reduced. It is preferable that a compound capable of preventing and preventing the reaction is contained. Moreover, it is preferable that the compound which can carry out the oxidative bleaching of the silver atom thru | or metal silver (silver cluster) produced | generated at the time of preservation | save of a raw film or an image is contained. Specific examples of compounds having these functions include biimidazolyl compounds and iodonium compounds. The amount of the biimidazolyl compound and iodonium compound added is in the range of 0.001 to 0.1 mol / m ² , preferably 0.005 to 0.05 mol / m ² .

  When the reducing agent used in the present invention has an aromatic hydroxyl group (—OH), particularly in the case of bisphenols, a non-reducing compound having a group capable of forming a hydrogen bond with these groups is used. It is preferable to use together. Specific examples of particularly preferred hydrogen bonding compounds in the present invention include, for example, compounds (II-1) to (II-40) described in paragraphs [0061] to [0064] of JP-A-2002-90937. Is mentioned.

  On the other hand, many compounds that can release halogen atoms as active species are known as antifogging and image stabilizers. Specific examples of the compound that generates these active halogen atoms include compounds represented by general formula (9) described in JP-A-2002-287299, [0264] to [0271].

  The addition amount of these compounds is preferably within a range in which the increase in printout silver due to the formation of silver halide due to the reaction between the halogen released from the compound and silver ions does not become a problem. Specific examples of the compound that generates these active halogen atoms include, in addition to the above-mentioned publications, compounds (III-1) to 3 described in paragraphs “0086” to “0087” of JP-A No. 2002-169249. (III-23), compounds 1-1a to 1-1o and 1-2a to 1-2o described in paragraphs “0031” to “0034” of JP-A-2003-50441, and paragraphs “0050” to “0056” Compounds 2a to 2z, 2aa to 2ll, 2-1a to 2-1f, Compounds 4-1 to 4-32 described in paragraphs “0055” to “0058” of JP-A No. 2003-91054, paragraphs “0069” to Examples thereof include compounds 5-1 to 5-10 described in “0072”.

  Antifoggants preferably used in the present invention include, for example, compound examples a to j described in paragraph “0012” of JP-A-8-314059 and paragraph “0028” of JP-A-7-209797. Thiosulfonate esters A to K, compound examples (1) to (44) described from p14 of JP-A No. 55-140833, compounds described in paragraph “0063” of JP-A No. 2001-13627 (I-1 ) To (I-6), (C-1) to (C-3) described in paragraph “0066”, and compounds (III-1) to (III-) described in paragraph “0027” of JP-A-2002-90937. 108), compounds VS-1 to VS-7 and compounds HS-1 to HS-5 described in paragraph “0013” of JP-A-6-208192 as compounds of vinyl sulfones and / or β-halo sulfones. KS-1 to KS-8 compounds described in JP 2000-330235 A as sulfonylbenzotriazole compounds, PR-01 to PR-08 described in JP-T 2000-515995 as substituted propene nitrile compounds, Examples thereof include compounds (1) -1 to (1) -132 described in paragraphs “0042” to “0051” of JP-A-2002-207273.

  The antifoggant is generally used in an amount of at least 0.001 mole per mole of silver. Usually, the range is 0.01 to 5 moles of the compound relative to the moles of silver, preferably 0.02 to 0.6 moles of the compound relative to the moles of silver.

  In addition to the above compounds, the silver salt photothermographic dry imaging material of the present invention may contain various compounds conventionally known as antifoggants, but the same reaction activity as the above compounds. Even if it is a compound which can produce | generate a seed | species, 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. Examples thereof include compounds described in the specification, JP 4,756,999, JP-A-9-288328, and JP-A-9-90550. Further, as other antifoggants, compounds disclosed in US Pat. No. 5,028,523 and European Patent Nos. 600,587, 605,981 and 631,176 are exemplified. Can be mentioned.

(Toning agent)
The silver salt photothermographic dry imaging material of the present invention forms a photographic image by heat development processing, and a toning agent (toner) for adjusting the color tone of silver as required is usually contained in an (organic) binder matrix. It is preferably contained in a dispersed state.

  Examples of suitable toning agents used in the present invention include Research Disclosure (RD) 17029, U.S. Pat. Nos. 4,123,282, 3,994,732, 3,846,136, and the like. For example, the following are disclosed.

  Imides (eg, succinimide, phthalimide, naphthalimide, N-hydroxy-1,8-naphthalimide); mercaptans (eg, 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, combinations 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 derivatives and anhydrides thereof Products (eg, phthalic acid, 4-methylphthalic acid, 4 The combination and the like with at least one compound selected from nitrophthalic acid and tetrachlorophthalic anhydride). Particularly preferred toning agents are combinations of phthalazinone or phthalazine with phthalic acids and phthalic anhydrides.

(Fluorosurfactant)
In the present invention, a fluorine-based surfactant represented by the following general formula (SF) is preferable in order to improve film transportability and environmental suitability (accumulation in a living body) in a laser imager (heat development processing apparatus). Used.

General formula (SF)
(R _f − (L ₁ ) _n1 −) _p − (Y) _m1 − (A) _q
[Wherein R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, n1 and m1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, and q represents an integer of 1 to 3. However, when q is 1, n1 and m1 are not 0 at the same time. ]
In the general formula (SF), R _f represents a substituent containing a fluorine atom. Examples of the substituent containing the fluorine atom include a fluorinated alkyl group having 1 to 25 carbon atoms (for example, trifluoromethyl). Group, trifluoroethyl group, perfluoroethyl group, perfluorobutyl group, perfluorooctyl group, perfluorododecyl group and perfluorooctadecyl group) or fluorinated alkenyl group (for example, perfluoropropenyl group, perfluorobutenyl group) Perfluorononenyl group, perfluorododecenyl group, etc.). R _f preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. R _f preferably has 2 to 12 fluorine atoms, more preferably 3 to 12 fluorine atoms.

L ₁ represents a divalent linking group having no fluorine atom. Examples of the divalent linking group having no fluorine atom include an alkylene group (for example, a methylene group, an ethylene group, a butylene group, etc.), Alkyleneoxy group (methyleneoxy group, ethyleneoxy group, butyleneoxy group, etc.), oxyalkylene group (for example, oxymethylene group, oxyethylene group, oxybutylene group, etc.), oxyalkyleneoxy group (for example, oxymethyleneoxy group, Oxyethyleneoxy group, oxyethyleneoxyethyleneoxy group, etc.), phenylene group, oxyphenylene group, phenyloxy group, oxyphenyloxy group, or a combination of these groups.

  A represents an anionic group or a salt thereof. For example, carboxylic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), sulfonic acid group or a salt thereof (sodium salt, potassium salt and lithium salt), sulfuric acid half ester Group or a salt thereof (sodium salt, potassium salt and lithium salt), a phosphoric acid group or a salt thereof (sodium salt, potassium salt and the like) and the like.

  Y represents a (p + q) -valent linking group having no fluorine atom. For example, the trivalent or tetravalent linking group having no fluorine atom is composed mainly of a nitrogen atom or a carbon atom. An atomic group is mentioned. n1 represents 0 or an integer of 1, and is preferably 1.

The fluorine-based surfactant represented by the general formula (SF) is an alkyl compound having 1 to 25 carbon atoms into which a fluorine atom is introduced (for example, trifluoromethyl group, pentafluoroethyl group, perfluorobutyl group, perfluorooctyl). Group and a compound having a perfluorooctadecyl group) and an alkenyl compound (for example, a perfluorohexenyl group and a perfluorononenyl group), a trivalent to hexavalent alkanol compound in which no fluorine atom is introduced, and a hydroxyl group, respectively. aromatic compound or a compound obtained by addition reaction and condensation reaction between the hetero compound having 3 or 4 (part R _f of alkanols compounds), further for example, introducing an anionic group (a) with sulfuric acid esterification, etc. Can be obtained.

  Examples of the trivalent to hexavalent alkanol compound include glycerin, pentaerythritol, 2-methyl-2-hydroxymethyl 1,3-propanediol, 2,4-dihydroxy-3-hydroxymethylpentene, and 1,2,6-hexane. Examples include triol, 1,1,1-tris (hydroxymethyl) propane, 2,2-bis (butanol) -3, aliphatic triol, tetramethylolmethane, D-sorbitol, xylitol, D-mannitol and the like.

  Examples of the aromatic compound and hetero compound having 3 to 4 hydroxyl groups include 1,3,5-trihydroxybenzene and 2,4,6-trihydroxypyridine.

  Specific examples of the above-described fluorosurfactants include compounds (FS-1) to (FS-66) described in paragraphs “0029” to “0040” of JP-A No. 2003-149766, JP-A No. 2004-021084. Compound 1-1 to 1-4 described in paragraph “0014” of compound No., compounds 2-1 to 2-10 described in paragraph “0019”, and paragraph “0025” of Japanese Patent Application Laid-Open No. 2004-077772. Examples thereof include compounds described in paragraph “0030”.

  Below, the preferable specific compound of the fluorine-type surfactant represented by general formula (SF) is shown.

  Further, as fluorine surfactants other than those described above, compounds described in paragraph “0035” of JP-A No. 2004-117505, JP-A No. 2000-214554, JP-A No. 2003-156819, JP-A No. 2003-177494 are disclosed. The compounds described in JP-A No. 2003-114504, JP-A 2003-270754, and JP-A 2003-270760 may be used. In the present invention, it is particularly preferable to use a combination of an anionic fluorine-containing surfactant represented by the general formula (SF) and a known nonionic fluorine-containing surfactant from the viewpoint of improving charging characteristics and coating properties.

  As a method for adding the fluorosurfactant represented by the general formula (SF) of the present invention to the coating solution, it can be added according to a known addition method. That is, it can be dissolved and added in alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polar solvents such as dimethyl sulfoxide and dimethylformamide. Further, fine particles having a size of 1 μm or less can be added after being dispersed in water or an organic solvent by sand mill dispersion, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion. Many techniques for fine particle dispersion are disclosed, but they can be dispersed according to these techniques. The fluorine-based surfactant represented by the general formula (SF) is preferably added to the outermost protective layer.

The amount of the fluorosurfactant represented by the general formula (SF) of the present invention is preferably 1 × 10 ⁻⁸ to 1 × 10 ⁻¹ mol per 1 m ² , and 1 × 10 ⁻⁵ to 1 × 10 ^−2. Mole is particularly preferred. If the range is less than the former range, the charging characteristics may not be obtained. If the range exceeds the former range, the humidity dependency is large and the storage stability under high humidity may be deteriorated.

(lubricant)
As the lubricant, for example, known lubricants described in paragraphs “0061” to “0064” of JP-A No. 11-84573 can be used. However, solid lubricant particles or a lubricant that is liquid at room temperature is used. It is preferable. Examples of the lubricant that is liquid at room temperature include compounds described in paragraph “0019” of JP-A No. 2003-15259. As the solid lubricant particles, organic solid lubricant particles having an average particle diameter of 1 to 30 μm are preferably used, and the melting point of the organic solid lubricant particles is preferably 110 ° C. or higher and 200 ° C. or lower.

(Surface layer)
The ten-point average roughness (Rz), maximum roughness (Rt), and centerline average roughness (Ra) in the present invention are defined by the following JIS surface roughness (B0601). Ten-point average roughness (Rz) is the peak from the highest to the fifth measured in the direction of the vertical magnification from the straight line that is parallel to the average line and does not cross the cross-sectional curve, in the portion that has been cut by the reference length from the cross-sectional curve. The difference between the average value of the altitude and the average value of the altitude at the bottom of the valley from the deepest to the fifth is expressed in micrometers (μm). The maximum roughness (Rt) is the roughness curve extracted by the reference length L, and when the extracted part is sandwiched between two straight lines parallel to the center line, the distance between the two straight lines is measured in the direction of the vertical magnification of the roughness curve. Then, this value is expressed in micrometers (μm). The centerline average roughness (Ra) is a portion of the measured length L extracted from the roughness curve in the direction of the centerline, the centerline of this extracted portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness curve Is represented by y = f (x), the value obtained by the following equation is expressed in micrometers (μm).

  As a method for measuring Rz, Rt, and Ra, the humidity was adjusted for 24 hours under the condition that the measurement samples were not overlapped in an environment of 25 ° C. and 65% RH, and then measured in the environment. The non-overlapping conditions shown here are, for example, a method of winding with the film edge portion raised, a method of stacking paper between the films, a method of making a frame with cardboard and fixing the four corners, etc. One of them. Examples of the measuring apparatus that can be used include a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO.

  In order to set Rz, Rt, and Ra on the front and back surfaces of the photosensitive material within the scope of the present invention, it can be easily adjusted by appropriately combining the following technical means.

1) Type of matting agent (inorganic or organic powder) contained in the layer on the side having the photosensitive layer and the layer opposite to the side having the photosensitive layer, average particle size, amount added, surface treatment method 2) Matting agent Dispersion conditions (type of disperser used, dispersion time, type of beads used for dispersion, average particle size, type and amount of dispersant used during dispersion, type of polar group of binder, polar group content)
3) Drying conditions during application (application speed, distance from the application surface of the hot air blowing nozzle, amount of dry air), amount of residual solvent 4) Type of filter used for filtration of coating liquid, filtration time 5) Calendar treatment after application Conditions (for example, calendar temperature 40-80 ° C, pressure 50-300 kg / cm, line speed 20-100 m / min, nip number 2-6)
In the present invention, the value of Rz (E) / Rz (B) is preferably 0.1 or more and 0.7 or less, and particularly the value of Rz (E) / Rz (B) is 0.2 or more, It is preferably 0.6 or less, more preferably 0.3 or more and 0.55 or less. Here, (E) represents the outermost surface on the photosensitive layer side, and (B) represents the outermost surface on the back coat layer side opposite to the photosensitive layer. By setting it as this range, the transportability of the film is good, and the occurrence of uneven density during thermal development can be remarkably improved.

  In the present invention, the value of Ra (E) / Ra (B) is preferably 0.6 or more and 1.5 or less, and particularly the value of Ra (E) / Ra (B) is 0.6 or more. 1.3 or less, more preferably 0.7 or more and 1.1 or less. By setting it within this range, the increase in fog over time is small, the transportability of the film is good, and the occurrence of uneven density during thermal development can be further improved.

  The photothermographic dry imaging material of the present invention preferably has constituent layers containing a plurality of types of matting agents on both sides on the support, from the viewpoint of improving the image quality of the image. The average particle diameter of the matting agent having the maximum average particle diameter of the matting agent contained in the layer containing the matting agent on the side having the photosensitive layer is Le (μm), opposite to the side having the photosensitive layer across the support. When the average particle diameter of the matting agent having the maximum average particle diameter of the matting agent contained in the layer containing the matting agent on the side, that is, the side having the back coat layer is Lb (μm), Lb / Le is 2.0 to It is preferable that it is 10, More preferably, it is 3.0-4.5.

  By setting Lb / Le within this range, density unevenness during heat development can be improved. In the image forming method of the present invention, the value of Rz (E) / Ra (E) is preferably 12 or more and 60 or less, more preferably 14 or more and 50 or less. By setting the value of Rz (E) / Ra (E) within this range, density unevenness during thermal development and storage characteristics over time can be improved.

  In the image forming method of the present invention, the value of Rz (B) / Ra (B) is preferably 25 or more and 65 or less, more preferably 30 or more and 60 or less. By setting the value of Rz (B) / Ra (B) within this range, density unevenness during heat development and storage characteristics over time can be improved. About the above-mentioned surface roughness, it carried out with the following method.

<< Evaluation of surface roughness >>
About the sample before the process of heat development, it measured by the method shown below using the non-contact three-dimensional surface analyzer (WYKO company RST / PLUS).

1) Objective lens: × 10.0, Intermediate lens: × 1.0
2) Measurement range: 463.4 μm × 623.9 μm
3) Pixel size: 368 × 238
4) Filter: Cylindrical correction and tilt correction 5) Smoothing: Medium smoothing 6) Scanning speed: Low
Ra, Rz, and Rt were defined according to JIS surface roughness (B0601). For each sample of 10 cm × 10 cm, the sample was divided into 100 in a grid pattern at 1 cm intervals, the center of each square region was measured, and the average value was obtained from 100 measurements.

  In the present invention, the case where the layer containing the matting agent is the outermost layer is one of the preferred embodiments. That is, even when a non-photosensitive layer is provided on the opposite side of the photosensitive layer of the silver salt photothermographic dry imaging material of the present invention, the surface roughness is controlled as the outermost layer. For this purpose, it is preferable to use organic or inorganic powder as a matting agent.

As the powder used in the present invention, a powder having a Mohs hardness of 5 or more is preferably used. As the powder, a known inorganic powder or organic powder can be appropriately selected and used. Examples of the inorganic powder include titanium oxide, boron nitride, SnO ₂ , SiO ₂ , Cr ₂ O ₃ , α-Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, SiC, cerium oxide, corundum, artificial Examples thereof include diamond, garnet, garnet, mica, silica, silicon nitride, silicon carbide and the like. Examples of the organic powder include powders such as polymethyl methacrylate, polystyrene, and Teflon (registered trademark). Among these, inorganic powders such as SiO ₂ , titanium oxide, barium sulfate, α-Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, Cr ₂ O ₃ , mica, etc. are preferable. SiO ₂ and α-Al ₂ O ₃ are preferable, and SiO ₂ is particularly preferable.

In the present invention, the powder is preferably surface-treated, for example. The surface treatment layer is formed by dry pulverizing the inorganic powder material, adding water and a dispersing agent, and performing coarse particle classification by wet pulverization and centrifugal separation. Thereafter, the fine slurry is transferred to a surface treatment tank, where the surface of the metal hydroxide is coated. First, a predetermined amount of an aqueous salt solution such as Al, Si, Ti, Zr, Sb, Sn, and Zn is added, and an acid or alkali that neutralizes the solution is added, and the surface of the inorganic powder particles is coated with the resulting hydrous oxide. To do. Water-soluble salts produced as a by-product are removed by decantation, filtration, and washing. Finally, the slurry pH is adjusted, filtered, and washed with pure water. The washed cake is dried with a spray dryer or a band dryer. Finally, the dried product is pulverized by a jet mill to become a product. In addition to the aqueous system, AlCl ₃ and SiCl ₄ vapors can be passed through the non-magnetic inorganic powder, and then steam can be introduced to perform Al and Si surface treatment. For other surface treatment methods, “Characterization of Powder Surfaces”, Academic Press can be referred to.

  In the present invention, it is preferable that the surface treatment is performed with an Si compound or an Al compound. When such a surface-treated powder is used, the dispersion state when the matting agent is dispersed can be improved. The content of Si or Al is preferably 0.1 to 10% by mass of Si and 0.1 to 10% by mass of Al, more preferably 0.1 to 10% by mass with respect to the powder. It is particularly preferable that 5% by mass, Al is 0.1-5% by mass, Si is 0.1-2% by mass, and Al is 0.1-2% by mass. The mass ratio of Si and Al is preferably Si <Al. The surface treatment can be performed by the method described in JP-A-2-83219. The average particle diameter of the powder in the present invention is the average diameter in the case of spherical powder, the average major axis length in the case of acicular powder, and the maximum diagonal length of the plate-like surface in the case of plate-like powder. Mean values can be easily obtained from measurement with an electron microscope.

  The organic or inorganic powder preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm.

  The average particle diameter of the organic or inorganic powder contained in the outermost layer on the photosensitive layer side is usually 0.5 to 8.0 μm, preferably 1.0 to 6.0 μm, more preferably 2.0 to 5.0 μm. It is.

  The addition amount is usually 1.0 to 20% by mass, preferably 2.0 to 15% by mass, more preferably 3 with respect to the amount of binder used in the outermost layer (including the crosslinking agent in the binder amount). 0.0 to 10% by mass.

  The average particle size of the organic or inorganic powder contained in the outermost layer opposite to the photosensitive layer side across the support is usually 2.0 to 15.0 μm, preferably 3.0 to 12.0 μm. More preferably, it is 4.0-10.0 micrometers. The addition amount is usually 0.2 to 10% by mass, preferably 0.4 to 7% by mass, and more preferably 0 to the amount of binder used in the outermost layer (including the crosslinking agent in the binder amount). .6 to 5% by mass.

  The variation coefficient 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.

{(Standard deviation of particle size) / (Average value of particle size)} × 100
The method of adding the organic or inorganic powder may be a method in which the organic or inorganic powder is previously dispersed in the coating solution, or a method of spraying the organic or inorganic powder after the coating solution is applied and before the drying is completed. May be. Moreover, when adding several types of powder, you may use both methods together.

(Dye, pigment)
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. It is preferable to contain a dye or pigment in the layer.

  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, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-083655 (this specification) Used as a thiopyrylium squarylium dye) and a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), or a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. It is preferable to do.

  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 dyes, U.S. Pat. No. 5,380,635, JP-A-8-201959, JP-A-2002-040593, JP-A-2003-186135, JP-A-2003-195450, U.S. Pat. The compounds described in (1) can also be preferably used.

(Support)
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 (aluminum, etc.), etc. For handling, a material that can be processed into a flexible sheet or roll is preferable. Therefore, as a support in the photothermographic dry imaging material of the present invention, cellulose acetate film, polyester film, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polyamide film, polyimide film, cellulose triacetate film (TAC) Alternatively, a plastic film such as a polycarbonate (PC) film is preferable, and a biaxially stretched PET film is particularly preferable. The thickness of the support is about 50 to 300 μm, preferably 70 to 180 μm.

  In order to improve the charging property, a conductive compound such as a metal oxide and / or a conductive polymer can be included in the constituent layer. These may be contained in any layer, but are preferably contained in the backing layer or the surface protective layer on the photosensitive layer side, the undercoat layer and the like. The conductive compounds described in columns 14 to 20 of US Pat. No. 5,244,773 are preferably used. Among these, in the present invention, the surface protective layer on the backing layer side preferably contains a conductive metal oxide. This proved that the effects of the present invention (particularly the transportability during heat development) can be further enhanced.

Here, the conductive metal oxide is crystalline metal oxide particles, and those containing oxygen defects and those containing a small amount of hetero atoms forming a donor with respect to the metal oxide used are generally used. In particular, it is particularly preferable because of its high conductivity, and the latter is particularly preferable because it does not give fog to the silver halide emulsion. Examples of metal oxides are ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , V ₂ O _5, etc., or a composite oxide thereof, especially ZnO, TiO ₂ and SnO ₂ are preferred. As an example of containing a heteroatom, addition Al, or In to ZnO, addition Sb, Nb, P, such as a halogen element relative to SnO _2, In addition, Nb for TiO _2, Ta Etc. are effective. The amount of these different atoms added is preferably in the range of 0.01 to 30 mol%, but particularly preferably 0.1 to 10 mol%. Furthermore, a silicon compound may be added during the production of fine particles in order to improve fine particle dispersibility and transparency.

The metal oxide fine particles used in the present invention have electrical conductivity, and the volume resistivity is 10 ⁷ Ω · cm or less, particularly 10 ⁵ Ω · cm or less. These oxides are described in JP-A Nos. 56-143431, 56-120519, 58-62647 and the like. Furthermore, as described in Japanese Examined Patent Publication No. 59-6235, a conductive material in which the above metal oxide is attached to other crystalline metal oxide particles or fibrous materials (such as titanium oxide) may be used. .

The particle size that can be used is preferably 1 μm or less, but if it is 0.5 μm or less, the stability after dispersion is good and it is easy to use. In order to make the light scattering property as small as possible, it is very preferable to use conductive particles of 0.3 μm or less because a transparent photosensitive material can be formed. Further, when the conductive metal oxide is needle-like or fibrous, the length is preferably 30 μm or less and the diameter is preferably 1 μm or less, particularly preferably the length is 10 μm or less and the diameter is 0.3 μm or less. The thickness / diameter ratio is 3 or more. As the SnO _2, are commercially available from Ishihara Sangyo Kaisha, it can be used SNS10M, SN-100P, SN- 100D, the FSS10M like.

(Component layer)
The silver salt photothermographic dry imaging material of the present invention has a photosensitive layer which is at least one image forming layer on a support. Although only the photosensitive layer may be formed on the support, it is preferable to form at least one non-photosensitive layer on the photosensitive layer. For example, a protective layer is preferably provided on the photosensitive layer for the purpose of protecting the photosensitive layer, and the opposite surface of the support is “sticking” between the photosensitive materials or in the photosensitive material roll. In order to prevent “,” a backcoat layer is provided.

  As a binder used in these protective layers and backcoat layers, a glass transition point (Tg) is higher than that of the photosensitive layer, and a polymer which is not easily scratched or deformed, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propio. Polymers such as nates are selected from the binders described above.

  For gradation adjustment or the like, 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.

(Application of component layers)
The silver salt photothermographic dry imaging material of the present invention is formed by preparing a coating solution in which the above-described constituent layers are dissolved or dispersed in a solvent, and applying a plurality of these 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, a protective layer) is prepared, and each layer is repeatedly coated and dried when it is coated on a support. Instead, it means that each constituent layer can be formed in such a state that a multilayer coating and drying process can be performed simultaneously. That is, the upper layer is provided before the remaining amount of all the solvents in the lower layer reaches 70% by mass or less (more preferably 90% by mass or less).

  There are no particular restrictions on the method of applying multiple layers simultaneously to each constituent layer, for example, bar coater method, curtain coating method, dipping method, air knife method, hopper coating method, reverse roll coating method, gravure coating method, and extrusion. A known method such as a coating method can be used.

  Of the various methods described above, the slide coating method and the extrusion coating method are more preferable. These coating methods have been described on the side having the photosensitive layer, but the same applies to the case of coating with undercoating when the back layer is provided. Japanese Unexamined Patent Publication No. 2000-15173 has a detailed description on the simultaneous multilayer coating method in the photothermographic dry imaging material.

In the present invention, the silver coating amount is preferably selected in accordance with the purpose of the silver salt photothermographic dry imaging material, but is 0.3 g / m ² or more for medical purposes. preferably .5g / m ² or less, 0.5 g / m ² or more, 1.5 g / m ² or less is more preferable. Among the applied silver amounts, those derived from silver halide preferably account for 2 to 18%, more preferably 5 to 15%, based on the total silver amount.

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

Furthermore, the coating density of the non-photosensitive long-chain aliphatic carboxylate is 1 × 10 ⁻¹⁷ g or more, 1 × 10 1 per silver halide grain of 0.01 μm or more (equivalent particle diameter equivalent to sphere). ^-14 g or less is preferable, and 1 x 10 ^-16 g or more and 1 x 10 ^-15 g or less are more preferable.

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

In the present invention, the silver salt photothermographic dry imaging material preferably contains a solvent in the range of 5 to 1,000 mg / m ² during development. It is more preferable to adjust so that it may be 10-150 mg / m < ² >. As a result, the photothermographic material has high sensitivity, low fog, and high maximum density. Examples of the solvent include those described in paragraph “0030” of JP-A No. 2001-264930. However, it is not limited to these. These solvents can be used alone or in combination of several kinds.

  The content of the solvent in the photothermographic material can be adjusted by changing conditions such as a temperature condition in a drying process after the coating process. The content of the solvent can be measured by gas chromatography under conditions suitable for detecting the contained solvent.

(Packaging body)
When storing the silver salt photothermographic dry imaging material of the present invention, oxygen transmission rate and / or water transmission rate are used to prevent density change and fog generation over time, or to improve curling, curling, etc. It is preferable to package with a low packaging material. The oxygen permeability is preferably 50 ml / m ² or less per day at 25 ° C. and 1.013 × 10 5 Pa, more preferably 10 ml / m ² or less, and even more preferably 1.0 ml / m ² or less. The moisture permeability is preferably 0.01 g / m ² · 40 ° C · 90% RH · day or less (according to JIS Z0208 cup method), more preferably 0.005 g / m ² · 40 ° C. · 90% RH · Day or less, more preferably 0.001 g / m ² · 40 ° C · 90% RH · day or less.

  Specific examples of the packaging material for the photothermographic material include, for example, JP-A-8-254793, JP-A-2000-206653, JP-A-2000-235241, JP-A-2002-062625, JP-A-2003-015261, JP 2003-057990 A, JP 2003-084397 A, JP 2003-098648 A, JP 2003-098635 A, JP 2003-107635 A, JP 2003-131337 A, JP 2003-146330 A, Special It is a packaging material described in Japanese Patent Application Laid-Open No. 2003-226439 and Japanese Patent Application Laid-Open No. 2003-228152. The void ratio in the package is 0.01 to 10%, preferably 0.02 to 5%. Nitrogen sealing is performed so that the nitrogen partial pressure in the package is 80% or more, preferably 90% or more. It is good to do. The relative humidity in the package is 10% to 60%, preferably 40% to 55%.

  Further, in the cutting process and the packaging process, in order to prevent image defects such as scratches and white spots, the cleanliness is US federal standard 209d class 10,000 or less as disclosed in, for example, JP-A-2004-341145. It is preferable to perform the work in the environment of

(Exposure of silver salt photothermographic dry imaging materials)
Regarding the exposure used for the exposure of the silver salt photothermographic dry imaging material of the present invention or the exposure in the image forming method of the present invention, there are various light sources, exposure times, etc. suitable for obtaining a desired appropriate image. The following conditions can be adopted.

  The silver salt photothermographic dry imaging material of the present invention preferably uses a laser beam when recording an image. In the present invention, it is desirable to use a light source suitable for the color sensitivity imparted to the photosensitive material. For example, when 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. However, the laser power is high, or the silver salt photothermographic dry imaging material Infrared semiconductor lasers (780 nm, 820 nm) are more preferably used from the standpoint of being transparent.

In particular, the photothermographic dry imaging material of the present invention exhibits its characteristics when it is exposed for a short time with light of high illuminance, preferably with a light amount of 1 mW / mm ₂ or more. The illuminance here refers to the illuminance when the photosensitive material after heat development has an optical density of 3.0. When exposure is performed at such high illuminance, the amount of light (= illuminance * exposure time) required to obtain a required optical density is reduced, and a high sensitivity system can be designed. More preferably, the amount of light is ² mW / mm ² or more and 50 W / mm ² or less, and more preferably 10 mW / mm ² or more and 50 W / mm ² or less.

Any light source may be used as long as it is as described above, but it can be preferably achieved by using a laser. As a laser preferably used for the photosensitive material of the present invention, a gas laser (Ar ⁺ , Kr ⁺ , He—Ne), a YAG laser, a dye laser, a semiconductor laser, and the like are preferable. In addition, a semiconductor laser and a second harmonic generation element can be used. Further, a blue to violet light emitting semiconductor laser (such as one having a peak intensity at a wavelength of 350 nm to 440 nm) can be used. An example of a blue to purple light emitting high-power semiconductor laser is Nichia's NLHV 3000E semiconductor laser.

  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 scanning 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 beam scanning is preferably 55 to 88 degrees, more preferably 60 to 86 degrees, and still more preferably 65 to 84 degrees. , Most preferably 70-82 degrees.

  The beam spot diameter on the exposure surface of the photosensitive material when the laser beam is scanned onto 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 “shift angle” from the vertical of the laser beam incident angle. 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, it is also preferable to perform exposure using a laser scanning exposure machine that emits scanning laser light that is a vertical multi. Compared with a longitudinal single mode scanning laser beam, image quality degradation such as occurrence of interference fringe-like unevenness is reduced. In order to make a vertical multiplex, methods such as using return light by combining and applying high-frequency superposition are preferable. Note that the vertical multi means that the exposure wavelength is not single, and the exposure wavelength distribution 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.

  Furthermore, as a third aspect, it is also preferable to form an image by scanning exposure using two or more laser beams. As such an image recording method using a plurality of laser beams, it is used in an image writing unit of a laser printer or a digital copying machine that writes an image line by line in one scan because of a demand for higher resolution and higher speed. For example, Japanese Patent Laid-Open No. 60-166916 is known. This is a method in which laser light emitted from a light source unit is deflected and scanned by a polygon mirror and imaged on a photoconductor via an fθ lens or the like. This is in principle the same laser scanning optics as a laser imager or the like. Device.

  The image formation of laser light on the photoconductor in the image writing means of a laser printer or digital copying machine is for one line from the image formation position of one laser light for the purpose of writing an image by a plurality of lines in one scan. The next laser beam is imaged by shifting. Specifically, the two light beams are close to each other on the image plane in the sub-scanning direction at an order of several tens of μm, and the print density is 400 dpi (dpi is the number of dots per inch = 2.54 cm). The sub-scanning direction pitch of the two beams is 63.5 μm, and 42.3 μm at 600 dpi. Unlike the method of shifting the resolution in the sub-scanning direction as described above, in the present invention, it is preferable to form an image by condensing two or more lasers at the same place on the exposure surface while changing the incident angle. At this time, the exposure energy on the exposure surface when writing with one normal laser beam (wavelength λ [nm]) is E, and N laser beams used for exposure have the same wavelength (wavelength λ [nm]). ), In the case of the same exposure energy (En), the range of 0.9 × E ≦ En × N ≦ 1.1 × E is preferable. By doing so, energy is secured on the exposure surface, but the reflection of each laser beam to the image forming layer is reduced because the exposure energy of the laser is low, and thus the occurrence of interference fringes is suppressed.

  In the above description, the wavelengths of the plurality of laser beams are the same as λ, but those having different wavelengths may be used. In this case, it is preferable that (λ−30) <λ1, λ2,... Λn ≦ (λ + 30) with respect to λ [nm].

In the image recording methods of the first, second, and third aspects described above, as lasers used for scanning exposure, generally well-known solid lasers such as ruby lasers, YAG lasers, glass lasers; Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He—Cd laser, N ₂ laser, excimer laser and other gas lasers; InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ lasers, semiconductor lasers such as GaSb lasers; chemical lasers, dye lasers, etc. can be selected and used in a timely manner, but among these, semiconductors with a wavelength of 600-1200 nm due to maintenance and light source size problems It is preferable to use laser light from a laser. 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 short axis diameter, and a long axis. The 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 photothermographic dry imaging material depending on the sensitivity and laser power at the lasing wavelength inherent to the silver salt photothermographic dry imaging material. .

(Laser imager)
The laser imager (heat development processing apparatus) according to the present invention supplies uniform and stable heat to the entire surface of a film supply unit represented by a film tray, a laser image recording unit, and a silver salt photothermographic dry imaging material. It is composed of a heat-developing device section and a conveying device section for discharging the photothermographic dry imaging material image-formed by heat development from the apparatus through laser recording from the film supply section.

  In the laser imager preferably used in the present invention, the ratio of the path length of the cooling section to the path length of the heat developing section is 1.5 or less, more preferably 0.1 or more and 1.2 or less. It is especially preferable that it is 2 or more and 1.0 or less. Here, the path length of the thermal development unit is a transport path length in which the photosensitive material is heated to the development temperature in the thermal development apparatus. The path length of the cooling unit is the path length from the heat development unit to the time when the photosensitive material is discharged from the area where the photosensitive material is shielded by the laser imager to the room light where the laser imager is installed. Say.

  In addition, the laser imager has a photosensitive layer with a cooling rate on the surface (hereinafter referred to as “non-photosensitive surface”) that does not have a photosensitive layer across the support of the silver salt photothermographic dry imaging material. It is preferable to have a function that can be set higher than the cooling rate of the side surface (hereinafter referred to as “photosensitive surface”).

  In the present invention, the ratio of the cooling rate of the non-photosensitive surface to the cooling rate of the photosensitive surface is preferably 1.1 or more. More preferably, it is 1.1-5.0, Most preferably, it is 1.5-3.0. The means for increasing the cooling rate of the non-photosensitive surface is not particularly limited, but it is a preferred embodiment that the non-photosensitive surface is directly brought into contact with a metal plate, a metal roller, a non-woven fabric, or a flocked roller. More preferably, it is also desirable to use a heat sink or a heat pipe together in order to positively discharge the heat accumulated in these members to the outside.

  It is possible to provide a small-sized laser imager with a high processing speed by using a laser imager with a short path length of the cooling unit whose ratio of the path length of the cooling unit to the path length of the heat developing unit is 1.5 or less. .

  The cooling time from the exit from the heat development portion to the discharge is arbitrary, but it is preferably from 0 second to 25 seconds. More preferably, it is 0 second or more and 15 seconds or less, and particularly preferably 5 seconds or more and 15 seconds or less.

  The path length through which the photosensitive material passes after exiting the thermal development section and before discharging is arbitrary, but is preferably 1 cm or more and 60 cm or less. More preferably, they are 5 cm or more and 50 cm or less, More preferably, they are 5 cm or more and 40 cm or less.

  The silver salt photothermographic dry imaging material of the present invention may be developed by any method, but is usually developed by raising the temperature of the photosensitive material exposed imagewise. The preferred development temperature is 80 to 250 ° C, preferably 100 to 140 ° C, more preferably 110 to 130 ° C. The development time is preferably 1 to 10 seconds, more preferably 2 to 10 seconds, and further preferably 3 to 10 seconds. If the heating temperature is less than 80 ° C., sufficient image density cannot be obtained in a short time. If the heating temperature exceeds 200 ° C., the binder melts, and not only the image itself such as transfer to a roller but also transportability and developing machine etc. Adversely affect. By heating, a silver image is generated by an oxidation-reduction reaction between an organic silver salt (which functions as an oxidizing agent) and a reducing agent. This reaction process proceeds without any supply of treatment liquid such as water from the outside. The time required for the heat development processing (the time required for the photosensitive material to be picked up and discharged from the tray portion) is preferably 60 seconds or less, and it is preferably 10 seconds or more and 50 seconds or less for emergency diagnosis. Is more preferable.

  Either a drum type heater or a plate type heater may be used as the thermal development method, but the plate heater method is more preferable. As a heat development method using a plate heater method, a method described in JP-A-11-133572, that is, a silver salt photothermographic dry imaging material in which a latent image is formed on silver halide grains by exposure is heated in a heat developing unit. A laser imager that obtains a visible image by contacting the heating means, wherein the heating means comprises a plate heater, and a plurality of pressing rollers are arranged to face each other along one surface of the plate heater, A developing method using a laser imager is preferable, in which the imaging material is passed between a pressing roller and the plate heater to perform thermal development.

  The linear velocity of the photosensitive material in the exposure section, the heat development section, and the cooling section is arbitrary, but a higher speed is preferable for rapid processing and improvement in throughput. The linear velocity is preferably 30 mm / second to 200 mm / second, more preferably 30 mm / second to 150 mm, and still more preferably 30 mm / second to 60 mm / second. By setting the conveyance speed within this range, density unevenness during heat development can be improved and the processing time can be shortened.

  A specific example of the laser imager of this aspect is shown in FIG. In order to perform the exposure process and the thermal development process at the same time, that is, in order to start development on a part of the sheet that has already been exposed while exposing a part of the sheet sensitive material, It is preferable that the distance between them is 0 cm or more and 50 cm or less, and this makes a series of processing time of exposure and development extremely short. A preferable range of this distance is 3 cm or more and 40 cm or less, and more preferably 5 cm or more and 30 cm or less. Here, the exposure part refers to the position where the light from the exposure light source is applied to the silver salt photothermographic dry imaging material, and the development part refers to the position where the photothermographic material is heated for the first time for thermal development. Say. In FIG. 1, reference numeral 6 denotes an exposure unit, and a portion where the photosensitive material conveyed from 4 in FIG.

  As a device, apparatus or means for heating, for example, a heating means typical as a heat generator using a hot plate, iron, hot roller, carbon, white titanium or the like may be used. More preferably, the silver salt photothermographic dry imaging material in which the protective layer is provided on the photosensitive layer is subjected to heat treatment by bringing the surface having the protective layer into contact with the heating means, in order to perform uniform heating. In addition, it is preferable from the viewpoint of thermal efficiency, workability, etc., and it is preferable that the surface on the side having the protective layer is conveyed while being in contact with the heat roller, and is developed by heat treatment.

  In the present invention, an image obtained by heat development at a heating temperature of 123 ° C. and a development time of 10 seconds is shown on orthogonal coordinates where the unit lengths of the diffusion density (Y axis) and the common logarithmic exposure (X axis) are equal. In the characteristic curve, the average gradation of 0.25 to 2.5 in terms of optical density with diffused light is preferably 2.0 to 4.0. By using such gradations, it is possible to obtain an image with high diagnostic recognizability even if the amount of silver is small.

  In the present invention, it is preferable that the maximum value of the image density after thermal development of the silver salt photothermographic dry imaging material of the present invention is 3.8 or more and 5.0 or less. If it is less than 3.8, there is no problem in normal diagnosis, but it may take more time for precise diagnosis such as mammography. On the other hand, if it exceeds 5.0, image storability at the time of light irradiation such as Schaukasten may deteriorate.

  In order to effectively adapt to the laser imager according to the present invention, the photosensitive layer and the non-photosensitive layer provided on at least one surface of the support of the silver salt photothermographic dry imaging material according to the present invention. The total dry film thickness is preferably 12 μm or more and 19 μm or less, and particularly preferably 14 μm or more and 18 μm or less. The dry film thickness of the photosensitive layer is preferably 4 μm or more and 16 μm or less, more preferably 6 μm or more and 14 μm or less, and particularly preferably 8 μm or more and 12 μm or less.

  In this invention, it is preferable that the dry film thickness of the photosensitive layer of the silver salt photothermographic dry imaging material of this invention is 4 micrometers or more and 16 micrometers or less. If it is less than 4 μm, the image density may not be sufficiently obtained. On the other hand, when the thickness exceeds 16 μm, image storability at the time of light irradiation such as Schaukasten may be deteriorated.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of PET support)
1) Film formation Using terephthalic acid and ethylene glycol, PET having an intrinsic viscosity of IV = 0.66 (measured in phenol / tetrachloroethane = 6/4 (mass ratio) at 25 ° C.) was obtained. This was pelletized, dried at 130 ° C. for 4 hours, melted at 300 ° C., extruded from a T-die, and rapidly cooled to produce an unstretched film having a thickness of 175 μm after heat setting.

This was longitudinally stretched 3.3 times using rolls having different peripheral speeds and then stretched 4.5 times with a tenter. The temperatures at this time were 110 ° C. and 130 ° C., respectively. Thereafter, the film was heat-fixed at 240 ° C. for 20 seconds and relaxed by 4% in the lateral direction at the same temperature. Thereafter, the chuck portion of the tenter was slit and then knurled at both ends, and wound at 4 kg / cm ² to obtain a roll having a thickness of 175 μm.

2) Surface corona treatment Using a solid state corona treatment machine 6KVA model manufactured by Pillar, both surfaces of the support were treated at 20 m / min at room temperature. From the current and voltage readings at this time, it was found that the support was processed at 0.375 kV · A · min / m ² . The treatment frequency at this time was 9.6 kHz, and the gap clearance between the electrode and the dielectric roll was 1.6 mm.

3) Undercoat 3-1) Preparation formulation 1 for the undercoat layer coating solution (for the undercoat layer on the photosensitive layer side)
59 g of pesresin A-520 (30% by mass solution) manufactured by Takamatsu Yushi Co., Ltd.
Polyethylene glycol monononyl phenyl ether (average ethylene oxide number = 8.5) 10% by mass solution 5.4 g
MP-1000 manufactured by Soken Chemical Co., Ltd. (polymer fine particles, average particle size 0.4 μm)
0.91g
935 ml of distilled water
Formula 2 (for back layer 1st layer)
Styrene-butadiene copolymer latex (solid content 40% by mass, styrene / butadiene mass ratio = 68/32) 158 g
2,4-Dichloro-6-hydroxy-S-triazine sodium salt (8% by mass aqueous solution) 20 g
10% 1% by weight aqueous solution of sodium laurylbenzenesulfonate
854 ml of distilled water
Formula 3 (for back layer 2nd layer)
SnO ₂ / SbO (9/1 mass ratio, average particle size 0.038 μm, 17 mass% dispersion)
84g
Gelatin (10 mass% aqueous solution) 89.2g
8.6 g of Metroise TC-5 (2% by mass aqueous solution) manufactured by Shin-Etsu Chemical Co., Ltd.
MP-1000 0.01g manufactured by Soken Chemical Co., Ltd.
10% 1% by weight aqueous solution of sodium dodecylbenzenesulfonate
NaOH (1% by mass) 6 ml
Proxel (ICI) 1ml
805 ml of distilled water
3-2) Undercoat After the corona discharge treatment is performed on both surfaces of the biaxially stretched polyethylene terephthalate support having a thickness of 175 μm, the undercoat coating solution formulation 1 is wet-coated with a wire bar on one side (photosensitive layer surface). It was applied so that the amount was 6.6 ml / m ² (per side) and dried at 180 ° C. for 5 minutes, and then the undercoat coating liquid formulation 2 was applied to this back surface (back surface) with a wire bar at a wet coating amount of 5 Apply to 7 ml / m ² , dry at 180 ° C. for 5 minutes, and further apply the undercoat coating liquid formulation 3 on the back surface (back surface) with a wire bar so that the wet coating amount is 7.7 ml / m ^2. And then dried at 180 ° C. for 6 minutes to prepare an undercoat support.

(Back layer)
1) Preparation of back layer coating liquid (Preparation of solid fine particle dispersion (a) of base precursor)
2.5 kg of the base precursor compound 1 and 300 g of a surfactant (trade name: Demol N, manufactured by Kao Corporation), 800 g of diphenylsulfone, 1.0 g of benzoisothiazolinone sodium salt and distilled water were added to make a total amount of 8 Then, the mixture was dispersed with beads using a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.). In the dispersion method, the mixed solution was fed to UVM-2 filled with zirconia beads having an average diameter of 0.5 mm by a diaphragm pump, and dispersed at an internal pressure of 50 hPa or more until a desired average particle size was obtained.

  The dispersion was subjected to spectral absorption measurement, and the ratio of absorbance at 450 nm to absorbance at 650 nm (D450 / D650) in the spectral absorption of the dispersion was dispersed to 3.0. The obtained dispersion was diluted with distilled water so that the concentration of the base precursor was 25% by mass, and filtered for removing dust (filter made of polypropylene having an average pore size of 3 μm) for practical use.

2) Preparation of Dye Solid Fine Particle Dispersion 6.0 kg of cyanine dye compound-1 and 3.0 kg of sodium p-dodecylbenzenesulfonate, 0.6 kg of surfactant Demol SNB manufactured by Kao Corporation, and an antifoaming agent ( Brand name: Surfinol 104E (manufactured by Nissin Chemical Co., Ltd.) 0.15 kg was mixed with distilled water to make a total liquid volume of 60 kg. The mixed solution was dispersed with 0.5 mm zirconia beads using a horizontal sand mill (UVM-2: manufactured by Imex Corporation).

  The dispersion was subjected to spectral absorption measurement and dispersed until the ratio of the absorbance at 650 nm to the absorbance at 750 nm (D650 / D750) in the spectral absorption of the dispersion was 5.0 or more. The obtained dispersion was diluted with distilled water so that the concentration of the cyanine dye was 6% by mass, and subjected to filter filtration (average pore size: 1 μm) for removing dust.

3) Preparation of antihalation layer coating solution Keep container at 40 ° C., gelatin 40 g, monodisperse polymethyl methacrylate fine particles (average particle size 8 μm, particle size standard deviation 0.4) 20 g, benzoisothiazolinone 0.1 g, 490 ml of water was added to dissolve the gelatin. Further, 2.3 ml of 1 mol / l sodium hydroxide aqueous solution, 40 g of the above dye solid fine particle dispersion, 90 g of the solid fine particle dispersion (a) of the above base precursor, 12 ml of 3% aqueous solution of sodium polystyrenesulfonate, 180 g of 10% SBR latex , Were mixed. Immediately before coating, 80 ml of a 4% aqueous solution of N, N-ethylenebis (vinylsulfonacetamide) was mixed to prepare an antihalation layer coating solution.

4) Preparation of back surface protective layer coating solution The container was kept at 40 ° C., and 40 g of gelatin, 35 mg of benzoisothiazolinone and 840 ml of water were added to dissolve the gelatin. Further, 5.8 ml of 1 mol / l sodium hydroxide aqueous solution, 1.5 g of liquid paraffin emulsion as liquid paraffin, 10 ml of 5% aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, 20 ml of 3% aqueous sodium polystyrene sulfonate, fluorine -Based surfactant (F-1) 2% solution 2.4 ml, fluorosurfactant (F-2) 2% solution 2.4 ml, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid A polymer (copolymerization mass ratio 57/8/28/5/2) 19% by mass of latex 32 g was mixed. Immediately before coating, 25 ml of a 4% aqueous solution of N, N-ethylenebis (vinylsulfonacetamide) was mixed to prepare a coating solution for the back surface protective layer.

5) Application of back layer On the back surface side of the undercoat support, an antihalation layer coating solution was applied to a gelatin coating amount of 0.52 g / m ^2, and a back surface protective layer coating solution was applied to a gelatin coating amount of 1. A simultaneous multilayer coating was applied so as to be 0.7 g / m ² , followed by drying to prepare a back layer.

(Image forming layer, intermediate layer, and surface protective layer)
1. Preparation of coating materials 1) Silver halide emulsion << Preparation of silver halide emulsion 1 >>
To a solution of 1421 ml of distilled water, 3.1 ml of a 1% by mass potassium bromide solution was added, and a solution containing 3.5 ml of 0.5 mol / L sulfuric acid and 31.7 g of phthalated gelatin was stirred in a stainless steel reaction vessel. While maintaining the liquid temperature at 30 ° C., the solution A diluted with 95.4 ml of distilled water added to 22.22 g of silver nitrate, 15.3 g of potassium bromide and 0.8 g of potassium iodide in a distilled water volume of 97.4 ml. The whole amount of the solution B diluted to 1 was added at a constant flow rate over 45 seconds. Thereafter, 10 ml of a 3.5% by mass aqueous hydrogen peroxide solution was added, and 10.8 ml of a 10% by mass aqueous solution of benzimidazole was further added. Further, a solution C in which distilled water was added to 51.86 g of silver nitrate to be diluted to 317.5 ml, a solution D in which 44.2 g of potassium bromide and 2.2 g of potassium iodide were diluted with distilled water to a volume of 400 ml was added to solution C. Was added at a constant flow rate over 20 minutes, and solution D was added by the controlled double jet method while maintaining pAg at 8.1. The total amount of potassium hexachloroiridium (III) was added 10 minutes after the start of the addition of Solution C and Solution D so that it would be 1 × 10 ⁻⁴ mole per mole of silver. Further, 5 seconds after the completion of the addition of the solution C, an aqueous solution of potassium iron (II) hexacyanide was added in an amount of 3 × 10 ⁻⁴ mol per mol of silver. The pH was adjusted to 3.8 using 0.5 mol / L sulfuric acid, stirring was stopped, and a precipitation / desalting / water washing step was performed. The pH was adjusted to 5.9 with 1 mol / L sodium hydroxide to prepare a silver halide dispersion having a pAg of 8.0.

The silver halide dispersion was maintained at 38 ° C. with stirring, 5 ml of a 0.34 mass% 1,2-benzisothiazolin-3-one methanol solution was added, and the temperature was raised to 47 ° C. after 40 minutes. 20 minutes after the temperature increase, sodium benzenethiosulfonate was added in a methanol solution to 7.6 × 10 ⁻⁵ mol per 1 mol of silver, and 5 minutes later, tellurium sensitizer C was added in a methanol solution to a ratio of 2. 9 × 10 ⁻⁴ mol was added and aged for 91 minutes. Thereafter, a methanol solution having a molar ratio of the spectral sensitizing dye A and the sensitizing dye B of 3: 1 was added in an amount of 1.2 × 10 ⁻³ mol as a total of the sensitizing dyes A and B per mol of silver. , N′-dihydroxy-N ″ -diethylmelamine in 1.3 ml of a 0.8 wt% methanol solution was added, and after another 4 minutes, 5-methyl-2-mercaptobenzimidazole was added to the methanol solution at a rate of 4.8 per mole of silver. × 10 ⁻³ mol, 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole in methanol solution to 5.4 × 10 ⁻³ mol and 1- (3-methyl in 1 mol of silver A silver halide emulsion 1 was prepared by adding 8.5 × 10 ⁻³ mol of ureido) -5-mercaptotetrazole sodium salt in an aqueous solution to 1 mol of silver.

  The grains in the prepared silver halide emulsion were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.042 μm and a sphere equivalent diameter variation coefficient of 20%. The particle size and the like were determined from an average of 1000 particles using an electron microscope. The [100] face ratio of the particles was determined to be 80% using the Kubelka-Munk method.

<< Preparation of silver halide emulsion 2 >>
In the preparation of silver halide emulsion 1, the liquid temperature at the time of grain formation was changed from 30 ° C. to 47 ° C., and solution B was changed to diluting 15.9 g of potassium bromide with distilled water to a volume of 97.4 ml, Solution D was changed to diluting 45.8 g of potassium bromide with distilled water to a volume of 400 ml, and the addition time of solution C was changed to 30 minutes to remove potassium hexacyanoiron (II) in the same manner. A silver halide emulsion 2 was prepared. Precipitation / desalting / washing / dispersion was carried out in the same manner as silver halide emulsion 1. Further, the addition amount of tellurium sensitizer C is 1.1 × 10 ⁻⁴ mol per mol of silver, and the addition amount of methanol solution of 3: 1 in the molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is silver. The total of sensitizing dye A and sensitizing dye B per mole is 7.0 × 10 ⁻⁴ mole, and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole is added to 1 mole of silver. Same as Emulsion 1 except that 3.3 × 10 ⁻³ mol and 1- (3-methylureido) -5-mercaptotetrazole sodium salt were changed to 4.7 × 10 ⁻³ mol added to 1 mol of silver. Spectral sensitization, chemical sensitization, and addition of 5-methyl-2-mercaptobenzimidazole and 1-phenyl-2-heptyl-5-mercapto-1,3,4-triazole to obtain silver halide emulsion 2 It was. The emulsion grains of the silver halide emulsion 2 were pure silver bromide cubic grains having an average sphere equivalent diameter of 0.080 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of silver halide emulsion 3 >>
In the preparation of silver halide emulsion 1, silver halide emulsion 3 was prepared in the same manner except that the liquid temperature at the time of grain formation was changed from 30 ° C. to 27 ° C. Further, precipitation / desalting / washing / dispersion was performed in the same manner as silver halide emulsion 1. The molar ratio of spectral sensitizing dye A and spectral sensitizing dye B is 1: 1 as a solid dispersion (gelatin aqueous solution), and the addition amount is 6 × 10 ⁻ as the total of sensitizing dye A and sensitizing dye B per mole of silver. ³ moles, the amount of tellurium sensitizer C added was changed to 5.2 × 10 ⁻⁴ moles per mole of silver, and bromoauric acid was changed to 5 × 10 ⁻⁴ moles of silver 3 minutes after the addition of tellurium sensitizers. A silver halide emulsion 3 was obtained in the same manner as Emulsion 1 except that 2 × 10 ⁻³ mol of mol and potassium thiocyanate were added per mol of silver. The emulsion grains of the silver halide emulsion 3 were silver iodobromide grains containing 3.5 mol% of iodine having an average sphere equivalent diameter of 0.034 μm and a sphere equivalent diameter variation coefficient of 20%.

<< Preparation of mixed emulsion A for coating solution >>
70% by weight of silver halide emulsion 1, 15% by weight of silver halide emulsion 2 and 15% by weight of silver halide emulsion 3 were dissolved, and 7% by mole of silver in a 1% by weight aqueous solution of benzothiazolium iodide. × 10 ^-3 mol was added. Further, 1- (3-methylureido)-was added so that the silver halide content per kg of the mixed emulsion for coating solution was 38.2 g as silver, and 0.34 g per kg of the mixed emulsion for coating solution. 5-mercaptotetrazole sodium salt was added.

Further, as “a compound in which a one-electron oxidant produced by one-electron oxidation can emit one electron or more”, compounds 1 and 20 and 26 are each 2 × 10 ⁻³ per mole of silver halide. Molar amounts were added.

2) Preparation of fatty acid silver dispersion << Preparation of fatty acid silver dispersion A >>
Henkel behenic acid (product name Edenor C22-85R) 87.6 kg, distilled water 423 L, 5 mol / L NaOH aqueous solution 49.2 L, t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react. To obtain a sodium behenate solution A. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution A and the total amount of the aqueous silver nitrate solution were each maintained at a constant flow rate for 93 minutes 15 Added over seconds and 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution A is started. After the addition of the aqueous silver nitrate solution is completed, only the sodium behenate solution A is added for 14 minutes and 15 seconds. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system for the sodium behenate solution A was prepared by keeping warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution A and the addition position of the silver nitrate aqueous solution were symmetrically arranged around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of sodium behenate solution A, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.

When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.14 μm, b = 0.4 μm, c = 0.6 μm, average aspect ratio 5.2, average sphere equivalent diameter. It was a flake-like crystal having a variation coefficient of 15% for a sphere equivalent diameter of 0.52 μm. (A, b, and c are provisions in this specification)
19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurryed with a dissolver blade. : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to 1260 kg / cm ² by adjusting the pressure of the disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

<< Preparation of fatty acid silver dispersion B >>
<Preparation of recrystallized behenic acid>
100 kg of behenic acid (product name Edenor C22-85R) manufactured by Henkel was mixed in 1200 kg of isopropyl alcohol, dissolved at 50 ° C., filtered through a 10 μm filter, cooled to 30 ° C., and recrystallized. The cooling speed during recrystallization was controlled at 3 ° C./hour. The obtained crystals were centrifugally filtered, washed with 100 kg of isopropyl alcohol, and then dried. When the obtained crystals were esterified and subjected to GC-FID measurement, the behenic acid content was 96%, and in addition, 2% lignoceric acid, 2% arachidic acid, and 0.001% erucic acid were contained.

<Preparation of fatty acid silver dispersion B>
Recrystallized behenic acid 88 kg, distilled water 422 L, 5 mol / L NaOH aqueous solution 49.2 L and t-butyl alcohol 120 L were mixed and stirred at 75 ° C. for 1 hour to react to obtain sodium behenate solution B. Separately, 206.2 L (pH 4.0) of an aqueous solution containing 40.4 kg of silver nitrate was prepared and kept warm at 10 ° C. A reaction vessel containing 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30 ° C., and with sufficient stirring, the total amount of the previous sodium behenate solution B and the total amount of silver nitrate aqueous solution were kept at a constant flow rate for 93 minutes 15 Added over seconds and 90 minutes. At this time, only the silver nitrate aqueous solution is added for 11 minutes after the start of the addition of the aqueous silver nitrate solution, and then the addition of the sodium behenate solution B is started. After the addition of the aqueous silver nitrate solution is completed, only the sodium behenate solution B is added for 14 minutes and 15 seconds. Was added. At this time, the temperature in the reaction vessel was 30 ° C., and the external temperature was controlled so that the liquid temperature was constant. The pipe of the addition system for the sodium behenate solution B was kept warm by circulating hot water outside the double pipe so that the liquid temperature at the outlet at the tip of the addition nozzle was 75 ° C. Moreover, the piping of the addition system of the silver nitrate aqueous solution was kept warm by circulating cold water outside the double pipe. The addition position of the sodium behenate solution B and the addition position of the silver nitrate aqueous solution were symmetrically arranged around the stirring axis, and were adjusted so as not to contact the reaction solution.

  After completion of the addition of the sodium behenate solution B, the mixture was left stirring for 20 minutes at the same temperature, heated to 35 ° C. over 30 minutes, and then aged for 210 minutes. Immediately after completion of aging, the solid content was separated by centrifugal filtration, and the solid content was washed with water until the conductivity of filtered water reached 30 μS / cm. Thus, a fatty acid silver salt was obtained. The obtained solid content was stored as a wet cake without drying.

When the morphology of the obtained silver behenate particles was evaluated by electron microscope photography, the average values were a = 0.21 μm, b = 0.4 μm, c = 0.4 μm, average aspect ratio 2.1, and equivalent sphere diameter. The crystal had a coefficient of variation of 11%. (A, b, and c are provisions in this specification)
19.3 kg of polyvinyl alcohol (trade name: PVA-217) and water are added to a wet cake corresponding to a dry solid content of 260 kg to make a total amount of 1000 kg, and then slurryed with a dissolver blade. : PM-10 type).

Next, the pre-dispersed stock solution is adjusted to a pressure of 1150 kg / cm ² in a disperser (trade name: Microfluidizer M-610, manufactured by Microfluidics International Corporation, using a Z-type interaction chamber) three times. Treatment gave a silver behenate dispersion. The cooling operation was carried out by installing a serpentine heat exchanger before and after the interaction chamber, and adjusting the temperature of the refrigerant to a dispersion temperature of 18 ° C.

3) Preparation of reducing agent dispersion << Preparation of reducing agent dispersion >>
10 kg of water was added to 16 kg of a 10 wt% aqueous solution of a reducing agent (type and amount described in Table 1) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203), and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, dispersed for 3 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0. 2 g and water were added to prepare a reducing agent concentration of 25% by mass. This dispersion was heat-treated at 60 ° C. for 5 hours to obtain a reducing agent dispersion. The reducing agent particles contained in the reducing agent dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.4 μm or less. The obtained reducing agent dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

4) Preparation of hydrogen bonding compound-1 dispersion 10 kg of hydrogen bonding compound-1 (tri (4-t-butylphenyl) phosphine oxide) and modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) 10 kg of water was added to 16 kg of the aqueous solution and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump, and dispersed for 4 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare a hydrogen bonding compound concentration of 25% by mass. The dispersion was heated at 40 ° C. for 1 hour and then further heated at 80 ° C. for 1 hour to obtain a hydrogen bonding compound-1 dispersion. The hydrogen bonding compound particles contained in the hydrogen bonding compound dispersion thus obtained had a median diameter of 0.45 μm and a maximum particle diameter of 1.3 μm or less. The obtained hydrogen bonding compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

5) Preparation of Development Accelerator-1 Dispersion 10 kg of Development Accelerator-1 and 20 kg of 10% by weight aqueous solution of modified polyvinyl alcohol (Kuraray Co., Ltd., Poval MP203) were added with 10 kg of water and mixed well. To make a slurry. This slurry was fed with a diaphragm pump and dispersed for 3 hours 30 minutes in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm, and then benzoisothiazolinone sodium salt 0.2 g and water were added to adjust the concentration of the development accelerator to 20% by mass to obtain a development accelerator-1 dispersion. The development accelerator particles contained in the development accelerator dispersion thus obtained had a median diameter of 0.48 μm and a maximum particle diameter of 1.4 μm or less. The obtained development accelerator dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

6) Dispersion Preparation of Development Accelerator-2 and Color Toner Adjusting Solid Dispersion of Development Accelerator-2 and Yellow Coloring Leuco Dye YA-1 and Cyan Coloring Leuco Dye CLB-1 as Color Toner Were also dispersed in the same manner as Development Accelerator-1 to obtain dispersions of 20% by mass, 15% by mass, and 15% by mass, respectively.

7) Preparation of polyhalogen compound << Preparation of organic polyhalogen compound-1 dispersion >>
10 kg of organic polyhalogen compound-1 (tribromomethanesulfonylbenzene), 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate, Then, 14 kg of water was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 26% by mass to obtain an organic polyhalogen compound-1 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.41 μm and a maximum particle diameter of 2.0 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 10.0 μm to remove foreign substances such as dust and stored.

<< Preparation of organic polyhalogen compound-2 dispersion >>
10 kg of an organic polyhalogen compound-2 (N-butyl-3-tribromomethanesulfonylbenzoamide), 20 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol (Poval MP203 manufactured by Kuraray Co., Ltd.), and 20 of sodium triisopropylnaphthalenesulfonate 0.4 kg of a mass% aqueous solution was added and mixed well to obtain a slurry. This slurry was fed with a diaphragm pump and dispersed for 5 hours in a horizontal sand mill (UVM-2: manufactured by Imex Co., Ltd.) filled with zirconia beads having an average diameter of 0.5 mm. 2 g and water were added to prepare an organic polyhalogen compound concentration of 30% by mass. This dispersion was heated at 40 ° C. for 5 hours to obtain an organic polyhalogen compound-2 dispersion. The organic polyhalogen compound particles contained in the polyhalogen compound dispersion thus obtained had a median diameter of 0.40 μm and a maximum particle diameter of 1.3 μm or less. The obtained organic polyhalogen compound dispersion was filtered through a polypropylene filter having a pore size of 3.0 μm to remove foreign substances such as dust and stored.

8) Preparation of Phthalazine Compound-1 Solution 8 kg of modified polyvinyl alcohol MP203 manufactured by Kuraray Co., Ltd. was dissolved in 174.57 kg of water, and then 3.15 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate and phthalazine compound-1 ( 14.28 kg of a 70% by weight aqueous solution of 6-isopropylphthalazine) was added to prepare a 5% by weight solution of phthalazine compound-1.

9) Preparation of mercapto compound << Preparation of aqueous solution of mercapto compound-1 >>
7 g of mercapto compound-1 (1- (3-sulfophenyl) -5-mercaptotetrazole sodium salt) was dissolved in 993 g of water to obtain a 0.7% by mass aqueous solution.

<< Preparation of Mercapto Compound-2 Aqueous Solution >>
20 g of mercapto compound-2 (1- (3-methylureido) -5-mercaptotetrazole sodium salt) was dissolved in 980 g of water to obtain a 2.0 mass% aqueous solution.

10) Preparation of Pigment-1 Dispersion C.I. I. Pigment Blue 60 (64 g) and Kao Corp. Demol N (6.4 g) were added to 250 g of water and mixed well to prepare a slurry. Prepare 800 g of zirconia beads having an average diameter of 0.5 mm, put them in a vessel together with the slurry, and disperse for 25 hours with a disperser (1/4 G sand grinder mill: manufactured by IMEX Co., Ltd.). A pigment-1 dispersion was obtained by adjusting the concentration to 5% by mass. The pigment particles contained in the pigment dispersion thus obtained had an average particle size of 0.21 μm.

11) Preparation of binder liquid (binder of the present invention)
As the binder, each of the polymer latex selected from the exemplary compounds (P-1) to (P-29) was adjusted to pH 8.35 using 25% NH ₄ OH. Thereafter, the mixture is filtered through a polypropylene filter having a pore size of 1.0 μm to remove foreign substances such as dust and stored, and the binder liquids (P-1) to (P-29) of the present invention having a solid content concentration of 44 mass%. Was prepared.

(Comparative binder RP-1)
As a binder for the comparative sample, the exemplified compound (P-1) described in JP-A No. 2002-229149 was synthesized to obtain a binder RP-1 (Synthesis Example 1), which was prepared in the same manner as described above, and the comparative binder liquid RP (Styrene / butadiene / acrylic acid = 68/29/3 mass%, Tg = 17 ° C., solid content 44 mass%, particle size 80 nm).

(Comparative binder RP-2)
In Synthesis Example 1, the composition was changed to 496.8 g of styrene, 27 g of isoprene, and 16.2 g of acrylic acid to synthesize a binder RP-2 (Synthesis Example 2). (Styrene / isoprene / acrylic acid = 92/5/3 mass%: Tg = 86 ° C., solid content 44 mass%, particle size 115 nm).

(Comparative binder RP-3)
In Synthesis Example 2, the composition was changed to 118.8 g of styrene, 405 g of isoprene, and 16.2 g of acrylic acid to produce a binder RP-3 (Synthesis Example 3). (Styrene / isoprene / acrylic acid = 22/75/3 mass%: Tg = −40 ° C., solid content 44 mass%, particle size 108 nm).

(Comparative binder RP-4)
The exemplified compound (P-13) described in JP-A-2002-229149 was synthesized to obtain a binder RP-4 (Synthesis Example 4), adjusted in the same manner as described above, and compared with the binder liquid RP-4 (styrene / isoprene / tetra). And ethylene gyl alcohol methacrylate = 75/5/20 mass%, Tg = 38 ° C., solid content 44 mass%, particle size 90 nm).

2. Preparation of coating solution 1) Preparation of image forming layer coating solution-A1 to A16 (Preparation of image forming layer coating solution-A1)
1000 g of fatty acid silver dispersion B obtained above, 135 ml of water, 36 g of pigment-1 dispersion, 14.3 g of organic polyhalogen compound-1 dispersion, 22.3 g of organic polyhalogen compound-2 dispersion, 171 g of phthalazine compound-1 solution , 1060 g of binder liquid (types listed in Table 1: Latex concentration 44% by mass), 153 g of reducing agent dispersion (types and amounts described in Table 1), 55 g of hydrogen bonding compound-1 dispersion, development accelerator-1 4.8 g of dispersion, 5.2 g of development accelerator-2 dispersion, 2.1 g of solid dispersion of yellow coloring leuco dye YA-1 as a color tone adjusting agent dispersion, solid of cyan coloring leuco dye CLB-1 Coating solution in which 2.1 g of dispersion, 8 ml of mercapto compound-1 aqueous solution, and 8 ml of mercapto compound-2 aqueous solution were sequentially added, and silver halides 1, 2, and 3 were mixed immediately before coating. An image forming layer coating liquid A1 the mixed emulsion A140g were mixed well and added was fed directly to a coating die and coated.

  The viscosity of the image forming layer coating solution was 43 [mPa · s] at 40 ° C. (No. 1 rotor, 60 rpm) as measured with a B-type viscometer of Tokyo Keiki.

  The viscosity of the image-forming layer coating solution at 38 ° C. using RheoStress RS150 manufactured by Haake was 23 [mPa · s].

  The amount of zirconium in the coating solution was 0.30 mg per 1 g of silver.

2) Preparation of non-photosensitive intermediate layer coating solution 1000 g of polyvinyl alcohol PVA-205 (manufactured by Kuraray Co., Ltd.), 163 g of pigment-1 dispersion, blue dye compound-1 (manufactured by Nippon Kayaku Co., Ltd .: Kayafect Turquoise RN) Liquid 150) aqueous solution 33 g, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5% aqueous solution 27 ml, methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio 57/8/28/5) / 2) 4200 ml of latex, 27 ml of 5% aqueous solution of aerosol OT (manufactured by American Cyanamid), 135 ml of 20% by weight aqueous solution of diammonium phthalate, and water so that the total amount is 10,000 g. In addition, adjust with NaOH so that the pH is 7.5. Thus, a non-photosensitive intermediate layer coating solution was supplied to the coating die so as to be 8.9 ml / m ² .

3) Preparation of surface protective layer first layer coating solution 100 g of inert gelatin and 10 mg of benzoisothiazolinone were dissolved in 840 ml of water, and a methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate / acrylic acid copolymer (copolymerization mass ratio) 57/8/28/5/2) Latex 19% by weight solution 180g, phthalic acid 15% by weight methanol solution 46ml, sulfosuccinic acid di (2-ethylhexyl) sodium salt 5% by weight aqueous solution 5.4ml was added. The mixture was mixed, and immediately before coating, 40 ml of 4% by weight chromium alum was mixed with a static mixer and fed to the coating die so that the amount of the coating solution was 26.1 ml / m ² .

4) Preparation of surface protective layer second layer coating solution (upper layer coating solution on the photosensitive layer side) 100 g of inert gelatin and 10 mg of benzoisothiazolinone are dissolved in 800 ml of water, and methyl methacrylate / styrene / butyl acrylate / hydroxyethyl methacrylate. / Acrylic acid copolymer (copolymerization mass ratio 57/8/28/5/2) 19 mass% latex 180 g, phthalic acid 15 mass% methanol solution 40 ml, fluorosurfactant (F-1) 1 mass 5.5 ml of a 1% solution, 5.5 ml of a 1% by weight aqueous solution of a fluorosurfactant (F-2), 28 ml of a 5% by weight aqueous solution of di (2-ethylhexyl) sodium sulfosuccinate, and polymethyl methacrylate fine particles ( 4 g of average particle size 0.7 μm) and 21 g of polymethyl methacrylate fine particles (average particle size 4.5 μm) were mixed. The ones with the surface protective layer a second layer coating solution (uppermost layer coating solution of the photosensitive layer side) was fed to a coating die so that 8.3 ml / m ^2.

3. Production of photothermographic material 1) Production of photothermographic material 101 to 125 Image forming layer, non-photosensitive intermediate layer, surface protective layer first layer, surface protective layer second layer from the undercoat surface to the surface opposite to the back surface Samples 101 to 125 were prepared by simultaneous multilayer coating by the slide bead coating method in the order of (the uppermost layer on the photosensitive layer side). At this time, the coating solution for the image forming layer and the non-photosensitive intermediate layer is 31 ° C., the coating solution for the first surface protective layer is 36 ° C., and the second surface protective layer (the uppermost layer on the photosensitive layer side). The temperature of the coating solution was adjusted to 37 ° C.

The coating amount (g / m ² ) of each compound in the image forming layer at this time is as follows. For sample 118, the coating amount of each compound was changed so that the dry film thickness of the photosensitive layer was 12 μm.

Silver behenate 4.43 (g / m ² )
Pigment (CI Pigment Blue 60) 0.030 (g / m ² )
Polyhalogen compound-1 0.084 (g / m ² )
Polyhalogen compound-2 0.168 (g / m ² )
Phthalazine compound-1 0.15 (g / m ² )
Binder 7.92 (g / m ² )
Reducing agent (types listed in Table 1) (amounts listed in Table 1)
Hydrogen bonding compound-1 0.24 (g / m ² )
Development accelerator-1 0.016 (g / m ² )
Development accelerator-2 0.013 (g / m ² )
Yellow coloring leuco dye (YA-1) 0.005 (g / m ² )
Cyan coloring leuco dye (CLB-1) 0.005 (g / m ² )
Mercapto compound-2 0.0025 (g / m ² )
Silver halide (as Ag) 0.11 (g / m ² )
The coating and drying conditions are as follows.

  The coating was performed at a speed of 160 m / min, the gap between the coating die tip and the support was set to 0.10 to 0.30 mm, and the pressure in the decompression chamber was set to be 196 to 882 Pa lower than the atmospheric pressure. The support was neutralized with an ion wind before coating.

  In the subsequent chilling zone, after cooling the coating solution with a wind at a dry bulb temperature of 10 to 20 ° C., it is transported in a non-contact type, and is dried at a dry bulb temperature of 23 to 45 ° C. It dried with the dry wind of the wet bulb temperature 15-21 degreeC.

  After drying, the humidity was adjusted at 40 ° C. to 60% RH at 25 ° C., and then the film surface was heated to 65 to 85 ° C. After heating, the film surface was cooled to 25 ° C.

  The photothermographic material thus prepared had a Beck smoothness of 550 seconds on the photosensitive layer surface side and 130 seconds on the back surface. Further, the pH of the film surface on the photosensitive layer surface side was measured and found to be 6.0. The dry thickness of the photosensitive layer was 15.0 μm for all samples other than Sample 118. The dry film thickness of the photosensitive layer of Sample 118 was 12.0 μm.

4). Performance Evaluation 1) Preparation The obtained samples were cut into half-cut sizes, packaged in the following packaging materials in an environment of 25 ° C. and 50% RH, stored at room temperature for 2 weeks, and then evaluated as follows.

2) Packaging material: PET 10 μm / PE 12 μm / aluminum foil 9 μm / Ny 15 μm / polyethylene 50 μm containing 3% carbon.

Oxygen permeability: 0.02 × 10 ⁻⁵ ml / Pa · m ² · 25 ° C. · day, moisture permeability: 0.10 × 10 ⁻⁵ g / Pa · m ² · 25 ° C. · day
(Sample evaluation)
Evaluation was carried out simultaneously with exposure with the laser imager (installation area 0.35 m ² ) shown in FIG. 1, and the obtained image was evaluated with a densitometer. Here, “thermal development at the same time as exposure” means a sheet photosensitive material made of a silver salt photothermographic dry imaging material, and development is performed on a part of the sheet that has already been exposed while being partially exposed. Means to be started. The distance between the exposed part and the developing part was 12 cm. The ratio of the path length of the cooling section to the path length of the heat development section was 0.8. At this time, the conveyance speed from the photosensitive material supply unit to the image exposure unit, the conveyance rate at the image exposure unit, and the conveyance rate at the thermal development unit were 32 mm / second, respectively, and the time required for the thermal development process (photosensitive The time taken from when the material was picked up at the tray section until it was discharged was 45 seconds. Further, the position of the bottom surface of the photosensitive material stock tray located at the bottom was 45 cm high from the floor surface. The photothermographic dry imaging material produced as described above is set in the film accommodating portion 4 of the laser imager shown in FIG. 1, and a film guide 10 (only a part of the conveyance roller 2 is set up to the outlet 7 is shown). It is conveyed by. The transported photothermographic dry imaging material is exposed by laser scanning from the photosensitive surface side of the exposure unit 6 by an exposure machine using a semiconductor laser having a longitudinal multimode wavelength of 660 nm by high frequency superimposition with a maximum output of 50 mW as an exposure source. Gave. At this time, an image was formed by setting the angle of the exposure surface of the photothermographic dry imaging material and the exposure laser beam to 75 degrees. In this method, 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, heat development was performed at 123 ° C. for 8 seconds so that the non-photosensitive surface of the photothermographic dry imaging material and the surface of the developing unit 3 were in contact with each other. (In the case of continuous processing, the interval time of heat development is 4 seconds.) The photothermographic dry imaging material subjected to heat development is cooled by the cooling member 5 on the non-photosensitive surface side, but FIG. FIG. 1B shows a plate shape. The laser imager was operated in a room conditioned at 23 ° C. and 50% RH.

  The exposure was performed in a stepped manner while reducing the exposure energy amount by log E0.05 step by step from the maximum output.

  Regarding samples 101 to 125, an absorption peak at a maximum absorption wavelength of 420 nm due to the yellow coloring leuco dye was observed. Further, in Samples 101 to 125, an absorption peak at a maximum absorption wavelength of 640 nm due to the cyan color-forming leuco dye was observed.

<Performance evaluation>
The following performance was evaluated for each heat-developed image.

<Image density>
The value of the highest density portion of the image obtained under the above conditions was measured with a densitometer and indicated as the image density.

<< Average gradation Ga value >>
The obtained sensitometric sample was subjected to concentration measurement using a PDM65 transmission densitometer (manufactured by Konica), and the measurement result was computer processed to obtain a characteristic curve. From this characteristic curve, an average gradation Ga value having an optical density of 0.25 to 2.5 was obtained.

《Fog》
The value of the unexposed portion of the image obtained under the above conditions was measured with a densitometer and indicated as fog density.

《Silver tone in high density area》
A chest X-ray image was printed on each photothermographic material sample, and the photothermographic treatment was performed so that the maximum density was 4.0 or more by appropriately adjusting the processing time. The silver color tone in the high density part after treatment (at a density of 2.5) was visually evaluated using a Schaukasten. A wet processed laser imager film manufactured by Konica was used as a standard sample at this time, and the relative color tone with respect to the standard sample was evaluated visually by 0.5 increments according to the following criteria.

5: The same color tone as the standard sample 4: Almost the same preferred color tone as the standard sample 3: Level slightly different from the standard sample, but practically no problem 2: Color tone clearly different from the standard sample 1: Unpleasant color tone different from the standard sample << Image preservation
For evaluation of image storage stability, the image recording material after heat development was stored for 10 days under the conditions of 60 ° C. and relative humidity of 40%, and the density change (ΔDmin) of the white background before and after that was measured.

<Raw preservation>
Evaluation of raw storage stability was made by storing the image recording material as it was packed in the packaging material before heat development for 10 days under conditions of 50 ° C. and 40% relative humidity, and then opening it again at 25 ° C. and 40% relative humidity. Thermal development was performed, and thermal development was performed at 25 ° C. and a relative humidity of 40% before storage, and the density change (ΔDmin) of the white background before and after storage was measured.

<Concentration fluctuation accompanying humidity fluctuation>
Difference between the value of the highest density part when heat development is performed at 25 ° C. and a relative humidity of 40% and the value of the highest density part when heat development is performed at 25 ° C. and a relative humidity of 90% (ΔDmax) was measured.

  From Table 1, the sample of the present invention, when subjected to high-speed heat development using a compact laser imager, has low fog and high maximum density, image storability, and raw storage when compared with the comparative sample. It is clear that the density, the silver tone, and the density fluctuation accompanying the humidity fluctuation are excellent.

1 is a schematic configuration diagram of a laser imager (thermal development recording apparatus) for thermally developing a silver salt photothermographic dry imaging material according to the present invention to form an image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film 2 Conveyance roller 3 Developing part 4 Film accommodating part 5 Cooling part 6 Exposure part 7 Exit 10 Film guide

Claims (15)

It has a photosensitive layer containing an organic silver salt, silver halide grains, a binder, and a reducing agent on a support, contains a compound represented by the following general formula (RD1) as the reducing agent, and is photosensitive. A silver salt photothermographic dry imaging material comprising a polymer obtained by copolymerization of a monomer represented by the following general formula (M) in an amount of 10% by mass or more and 70% by mass or less as a binder to be used for the conductive layer.

[Wherein, X ₁ represents a chalcogen atom or CHR ₁ , and R ₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group. At least one of R ₂ represents a secondary or tertiary alkyl group and may be the same or different. R ₃ represents an alkyl group having 1 to 20 carbon atoms in which at least one group has a hydroxyl group as a substituent, or an alkyl group having 1 to 20 carbon atoms in which a group capable of forming a hydroxyl group by being deprotected is used as a substituent. Represents a group, which may be the same or different. R ₄ represents a substitutable group on the benzene ring, and m and n each represents an integer of 0 to 2. ]
General formula (M)
CH ₂ = CR ₀₁ -CR ₀₂ = CH ₂
(In the formula, R ₀₁ and R ₀₂ are a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 6 carbon atoms. However, R ₀₁ and R ₀₂ are not simultaneously hydrogen atoms. ) The silver salt photothermographic dry imaging material according to claim 1, wherein R _{01 in the} general formula (M) is a hydrogen atom, and R ₀₂ is a methyl group. The silver salt photothermographic dry according to claim 1 or 2, wherein the polymer represented by the general formula (M) is a polymer obtained by copolymerizing an acid group-containing monomer in an amount of 1% by mass to 20% by mass. Imaging material. At least one group of R _{3 in} the general formula (RD1) has a C 3-20 alkyl group having a hydroxyl group as a substituent, or a group capable of forming a hydroxyl group by being deprotected as a substituent. The silver salt photothermographic dry imaging material according to any one of claims 1 to 3, which is an alkyl group having 3 to 20 carbon atoms. The dry film thickness of the said photosensitive layer is 4 micrometers or more and 16 micrometers or less, The silver salt photothermographic dry imaging material of any one of Claims 1-4 characterized by the above-mentioned. The silver salt photothermographic dry imaging material according to any one of claims 1 to 5, wherein the maximum image density after heat development is 3.8 or more and 5.0 or less. At least one of the constituent layers of the silver salt photothermographic dry imaging material contains a compound that develops color during heat development to form a dye image, and the maximum absorption wavelength of the dye image is from 360 nm to 450 nm. The silver salt photothermographic dry imaging material according to any one of claims 1 to 6. At least one of the constituent layers of the silver salt photothermographic dry imaging material contains a compound that develops color during heat development to form a dye image, and the maximum absorption wavelength of the dye image is 600 nm to 700 nm. The silver salt photothermographic dry imaging material according to any one of claims 1 to 7. The silver salt photothermographic dry imaging material according to claim 1, comprising a compound represented by the following general formula (SF).
General formula (SF)
(R _f − (L ₁ ) _m1 −) _p − (Y) _n1 − (A) _q
(In the formula, R _f represents a substituent containing a fluorine atom, L ₁ represents a divalent linking group having no fluorine atom, and Y represents a (p + q) -valent linking group having no fluorine atom. , A represents an anionic group or a salt thereof, m1 and n1 each represents an integer of 0 or 1, p represents an integer of 1 to 3, q represents an integer of 1 to 3, provided that q is 1. (M1 and n1 are not 0 at the same time.) The sheet-like silver salt photothermographic dry imaging material according to any one of claims 1 to 9, wherein the silver salt photothermographic dry imaging material is in a sheet form. An image forming method comprising transporting the sheet-like silver salt photothermographic dry imaging material according to claim 10 while heating at a transport speed of 30 to 200 mm / sec. While a part of one sheet-like silver salt photothermographic dry imaging material according to claim 10 is exposed, development is started on a part of the sheet-like silver salt photothermographic dry imaging material that has already been exposed. An image forming method. An image forming method comprising developing the sheet-like silver salt photothermographic dry imaging material according to claim 10 with a laser imager in which a distance between an exposure part and a development part is 0 cm or more and 50 cm or less. An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 10 is thermally developed by a laser imager with a heating time of 10 seconds or less. An image forming method, wherein the sheet-like silver salt photothermographic dry imaging material according to claim 10 is thermally developed by a laser imager having an installation area of 0.40 m ² or less.

Images