EP1584978A1 - Matériau photothermographique et procédé pour la production d'une image - Google Patents

Matériau photothermographique et procédé pour la production d'une image Download PDF

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Publication number
EP1584978A1
EP1584978A1 EP05006628A EP05006628A EP1584978A1 EP 1584978 A1 EP1584978 A1 EP 1584978A1 EP 05006628 A EP05006628 A EP 05006628A EP 05006628 A EP05006628 A EP 05006628A EP 1584978 A1 EP1584978 A1 EP 1584978A1
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EP
European Patent Office
Prior art keywords
group
photothermographic material
mol
weight
silver halide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP05006628A
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German (de)
English (en)
Inventor
Hajime Nakagawa
Yoshihisa Tsukada
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Fujifilm Corp
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Fuji Photo Film Co Ltd
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Publication of EP1584978A1 publication Critical patent/EP1584978A1/fr
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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49836—Additives
    • G03C1/49863—Inert additives, e.g. surfactants, binders
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49818—Silver halides
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/16—X-ray, infrared, or ultraviolet ray processes
    • G03C5/17—X-ray, infrared, or ultraviolet ray processes using screens to intensify X-ray images
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/0051—Tabular grain emulsions
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
    • G03C1/061—Hydrazine compounds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
    • G03C1/498—Photothermographic systems, e.g. dry silver
    • G03C1/49836—Additives

Definitions

  • the present invention relates to an improved photothermographic material and an image forming method. More specifically, the invention relates to a photothermographic material which exhibits a reduced degree of haze, high image quality, and excellent pressure resistance, and an image forming method utilizing the same.
  • images for medical imaging require a particularly high image quality excellent in sharpness and granularity since fine representation is required, and are characterized in that images of blue-black tones are preferred from the viewpoint of easy diagnosis.
  • various kinds of hard copy systems utilizing dyes or pigments such as ink jet printers and electrophotographic systems have been marketed as general image forming systems, but these are not satisfactory as output systems for medical images.
  • Such photothermographic materials generally comprise an image forming layer in which a catalytically active amount of photocatalyst (for example, a silver halide), a reducing agent, a reducible silver salt (for example, an organic silver salt), and if necessary, a toner for controlling the color tone of silver, are dispersed in a binder.
  • a photothermographic material forms a black silver image by being heated to a high temperature (for example, 80°C or higher) after imagewise exposure to cause an oxidation-reduction reaction between a silver halide or a reducible silver salt and a reducing agent.
  • the oxidation-reduction reaction is accelerated by the catalytic action of a latent image, which is generated on the silver halide grain by exposure.
  • the photosensitive material for photography as described herein means a photosensitive material on which images are recorded by one-shot exposing by camera work, rather than by writing the image information by scanning exposure with a laser beam or the like.
  • photosensitive materials for photography are generally used in the field of wet developing photosensitive materials, and direct or indirect radiography films, mammography films, and the like are widely known as photosensitive materials for use in medical imaging.
  • an X-ray photothermographic material coated on both sides using a blue fluorescent intensifying screen is described in Japanese Patent (JP) No.
  • JP-A Japanese Patent Application Laid-Open
  • a photosensitive material for medical use containing tabular grains that have a high content of silver chloride and have (100) major faces, and that are coated on both sides of a support is described in JP-A No. 10-282602.
  • Double-sided coated photothermographic materials are disclosed in JP-A Nos. 2000-227642, 2001-22027, 2001-109101, and 2002-90941.
  • developed images can be obtained from photothermographic materials by heating alone, they have many benifical features such as simple image forming operation, no need for controlling a wet processing solution or dispose thereof, and the like.
  • haze turbidity of a membrane
  • Another problem is an increase of fog known as print-out, which occurs because silver halide grains, unreacted organic silver salts, and reducing agents remain in the membrane.
  • a first aspect of the invention provides a photothermographic material comprising, on at least one side of a support, an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder, wherein: the photosensitive silver halide has an average silver iodide content of 40 mol% or higher, and at least 50% of a projected area of total grains of the photosensitive silver halide is occupied by tabular grains having an aspect ratio of 2 or more; and 50% by weight or more of the binder is formed by a polymer latex containing the following monomer component in a range of from 10% by weight to 70% by weight:
  • a second aspect of the invention provides an image forming method using the photothermographic material according to the first aspect, wherein the method comprises: (a) providing an assembly for forming an image by placing the photothermographic material between a pair of fluorescent intensifying screens; (b) putting an analyte between the assembly and an X-ray source; (c) applying exposure to the analyte using X-rays having an energy level in a range of 25 kVp to 125 kVp; (d) taking the photothermographic material out of the assembly; and (e) heating the photothermographic material at a temperature at which the material can be developed thermally.
  • the present inventors found that for the above two problems of turbity of the membrane (haze) and increase of fog known as print-out, the use of tabular photosensitive silver iodide grains is useful. Moreover the present invention solves the problem of generating a break at the surface of a photothermographic material when the material comprising the grains is impressed before thermal development by using a polymer having a specific monomer component for a binder in an image forming layer. In addition, the present invention provides a method for forming a radiation image with high sensitivity.
  • the photothermographic material of the invention has an image forming layer comprising at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder on at least one side of a support.
  • the image forming layer may have disposed thereon a surface protective layer, or a back layer, a back protective layer, or the like may be disposed on the opposite side of the image forming layer with respect to the support.
  • the image forming layer of the present invention may be disposed on one side, or may be disposed on both sides of the support. Particularly, in the case of photothermographic material used for forming a radiation image, the image forming layer is preferably coated on both sides.
  • the organic silver salt which can be used in the present invention is relatively stable to light but serves as to supply silver ions and forms silver images when heated to 80°C or higher under the presence of an exposed photosensitive silver halide and a reducing agent.
  • the organic silver salt may be any organic material containing a source capable of supplying silver ions that are reducible by a reducing agent.
  • Such a non-photosensitive organic silver salt is disclosed, for example, in JP-A No. 10-62899 (paragraph Nos. 0048 to 0049), European Patent (EP) No. 0803764A (page 18, line 24 to page 19, line 37), EP No. 0962812A1, JP-A Nos. 11-349591, 2000-7683, and 2000-72711, and the like.
  • a silver salt of an organic acid particularly, a silver salt of long chained aliphatic carboxylic acid (having 10 to 30 carbon atoms, and preferably having 15 to 28 carbon atoms) is preferable.
  • Preferred examples of the silver salt of fatty acid can include, for example, silver lignocerate, silver behenate, silver arachidinate, silver stearate, silver oleate, silver laurate, silver capronate, silver myristate, silver palmitate, silver erucate and mixtures thereof.
  • silver salt of fatty acid with a silver behenate content of 80 mol% to 99 mol%, more preferably, 85 mol% to 99 mol%, and further preferably, 95 mol% to 99 mol%. Further, it is preferred to use a silver salt of fatty acid with a silver erucate content of 2 mol% or less, more preferably, 1 mol% or less, and further preferably, 0.1 mol% or less.
  • organic silver salt usable in the invention there is no particular restriction on the shape of the organic silver salt usable in the invention and it may be needle-like, bar-like, tabular, or flake shaped.
  • the percentage for the value obtained by dividing the standard deviation for the length of minor axis and major axis by the minor axis and the major axis respectively is, preferably, 100% or less, more preferably, 80% or less and, further preferably, 50% or less.
  • the shape of the organic silver salt can be measured by analyzing a dispersion of an organic silver salt as transmission type electron microscopic images.
  • Another method of measuring the monodispersion is a method of determining of the standard deviation of the volume weighted mean diameter of the organic silver salt in which the percentage for the value defined by the volume weighted mean diameter (variation coefficient), is preferably, 100% or less, more preferably, 80% or less and, further preferably, 50% or less.
  • a commercially available laser-beam scattering grain size analyzer can be used.
  • Methods known in the art may be applied to the method for producing the organic silver salt used in the invention and to the dispersing method thereof.
  • the amount of the photosensitive silver salt to be disposed in the aqueous dispersion is preferably, 1 mol% or less, more preferably, 0.1 mol% or less per 1 mol of the organic acid silver salt in the solution and, further preferably, positive addition of the photosensitive silver salt is not conducted.
  • the photosensitive material can be prepared by mixing an aqueous dispersion of an organic silver salt and an aqueous dispersion of a photosensitive silver salt and the mixing ratio between the organic silver salt.
  • a method of mixing two or more kinds of aqueous dispersions of organic silver salts and two or more kinds of aqueous dispersions of photosensitive silver salts upon mixing is used preferably for controlling the photographic properties.
  • a total amount of coated silver including silver halide is preferably in a range from 0.1 g/m 2 to 5.0 g/m 2 , more preferably from 0.3 g/m 2 to 3.0 g/m 2 , and further preferably from 0.5 g/m 2 to 2.0 g/m 2 .
  • the total amount of coated silver is preferably 1.8 mg/m 2 or less, and more preferably 1.6 mg/m 2 or less.
  • the photothermographic material of the invention preferably contains a reducing agent for the organic silver salt.
  • the reducing agent may be any substance (preferably, organic substance) capable of reducing silver ions into metallic silver. Examples of the reducing agent are described in JP-A No. 11-65021 (column Nos. 0043 to 0045) and EP No. 0803764A1 (page 7, line 34 to page 18, line 12).
  • a so-called hindered phenolic reducing agent or a bisphenol reducing agent having a substituent at the ortho-position to the phenolic hydroxy group is preferred.
  • the compound represented by the following formula (R) is more preferred.
  • R 11 and R 11' each independently represent an alkyl group having 1 to 20 carbon atoms.
  • R 12 and R 12' each independently represent a hydrogen atom or a substituent capable of substituting for a hydrogen atom on a benzene ring.
  • L represents an -S- group or a -CHR 13 -group.
  • R 13 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
  • X 1 and X 1' each independently represent a hydrogen atom or a group capable of substituting for a hydrogen atom on a benzene ring.
  • R 12 and R 12' are, preferably, an alkyl group having 1 to 20 carbon atoms and can include, specifically, a methyl group, an ethyl group, a propyl group, a butyl group, an isopropyl group, a t-butyl group, a t-amyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a methoxymethyl group, a methoxyethyl group, and the like. More preferred are a methyl group, an ethyl group, a propyl group, an isopropyl group, and a t-butyl group.
  • X 1 and X 1' are, preferably, a hydrogen atom, a halogen atom, or an alkyl group, and more preferably, a hydrogen atom.
  • L is preferably a -CHR 13 - group.
  • R 13 is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms.
  • the alkyl group can include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a 2,4,4-trimethylpentyl group.
  • Particularly preferable R 13 is a hydrogen atom, a methyl group, an ethyl group, a propyl group, or an isopropyl group.
  • R 12 and R 12' are preferably an alkyl group having 2 to 5 carbon atoms, more preferably an ethyl group or a propyl group, and most preferably an ethyl group.
  • R 12 and R 12 are preferably a methyl group.
  • the primary or secondary alkyl group having 1 to 8 carbon atoms as R 13 is preferably a methyl group, an ethyl group, a propyl group, or an isopropyl group, and more preferably a methyl group, an ethyl group, or a propyl group.
  • R 13 is preferably a secondary alkyl group.
  • the secondary alkyl group as R 13 is preferably an isopropyl group, an isobutyl group, or a 1-ethylpentyl group, and more preferably an isopropyl group.
  • the reducing agent described above shows different thermal developing performances, color tones of developed silver images, or the like depending on the combination of R 11 , R 11' , R 12 , R 12' , and R 13 . Since these performances can be controlled by using two or more kinds of reducing agents at various mixing ratios, it is preferred to use two or more kinds of reducing agents in combination depending on the purpose.
  • the addition amount of the reducing agent is, preferably, from 0.1 g/m 2 to 3.0 g/m 2 , more preferably, 0.2 g/m 2 to 1.5 g/m 2 and, further preferably 0.3 g/m 2 to 1.0 g/m 2 . It is preferably contained in a range of 5 mol% to 50 mol%, more preferably, 8 mol% to 30 mol% and, further preferably, 10 mol% to 20 mol% per 1 mol of silver in the image forming layer.
  • the reducing agent of the invention is preferably contained in the image forming layer.
  • the reducing agent may be incorporated into photothermographic material by being added into the coating solution, such as in the form of solution, emulsion dispersion, solid fine particle dispersion, and the like.
  • emulsion dispersing method there can be mentioned a method comprising dissolving the reducing agent using an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate, or the like, as well as an auxiliary solvent such as ethyl acetate, cyclohexanone, or the like; from which an emulsion dispersion is mechanically produced.
  • an oil such as dibutyl phthalate, tricresyl phosphate, glyceryl triacetate, diethyl phthalate, or the like
  • an auxiliary solvent such as ethyl acetate, cyclohexanone, or the like
  • solid fine particle dispersing method there can be mentioned a method comprising dispersing the powder of the reducing agent in a proper medium such as water, by means of ball mill, colloid mill, vibrating ball mill, sand mill, jet mill, roller mill, or ultrasonics, thereby obtaining solid dispersion.
  • a protective colloid such as polyvinyl alcohol
  • a surfactant for instance, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of compounds having the isopropyl groups in different substitution sites).
  • the dispersion media In the mills enumerated above, generally used as the dispersion media are beads made of zirconia and the like, and Zr and the like eluting from the beads may be incorporated in the dispersion. Although depending on the dispersing conditions, the amount of Zr and the like generally incorporated in the dispersion is in the range from 1 ppm to 1000 ppm. It is practically acceptable so long as Zr is incorporated in an amount of 0.5 mg or less per 1 g of silver.
  • an antiseptic for instance, benzisothiazolinone sodium salt
  • an antiseptic for instance, benzisothiazolinone sodium salt
  • the reducing agent is used as a solid particle dispersion, and the reducing agent is added in the form of fine particles having mean particle size from 0.01 ⁇ m to 10 ⁇ m, and more preferably, from 0.05 ⁇ m to 5 ⁇ m, and further preferably, from 0.1 ⁇ m to 2 ⁇ m.
  • other solid dispersions are preferably used with this particle size range.
  • the development accelerator described above is used in a range from 0.1 mol% to 20 mol%, preferably, in a range from 0.5 mol% to 10 mol% and, more preferably, in a range from 1 mol% to 5 mol% with respect to the reducing agent.
  • the introducing methods to the photothermographic material can include similar methods as those for the reducing agent and, it is particularly preferred to add as a solid dispersion or an emulsion dispersion.
  • emulsion dispersion it is preferred to add as an emulsion dispersion dispersed by using a high boiling solvent which is solid at a normal temperature and an auxiliary solvent at a low boiling point, or to add as a so-called oilless emulsion dispersion not using the high boiling solvent.
  • hydrazine compounds represented by formula (D) described in the specification of JP-A No. 2002-156727 hydrazine compounds represented by formula (D) described in the specification of JP-A No. 2002-156727
  • phenolic or naphtholic compounds represented by formula (2) described in the specification of JP-A No. 2001-264929 phenolic or naphtholic compounds represented by formula (2) described in the specification of JP-A No. 2001-264929.
  • Particularly preferred development accelerators of the invention are compounds represented by the following formulae (A-1) and (A-2).
  • Formula (A-1) Q 1 -NHNH-Q 2 (wherein Q 1 represents an aromatic group or a heterocyclic group which bonds to -NHNH-Q 2 at a carbon atom, and Q 2 represents one selected from a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, and a sulfamoyl group).
  • the aromatic group or the heterocyclic group represented by Q 1 is preferably a 5 to 7-membered unsaturated ring.
  • Preferred examples include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a 1,2,4-triazine ring, a 1,3,5-triazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a 1,3,4-thiadiazole ring, a 1,2,4-thiadiazole ring, a 1,2,5-thiadiazole ring, a 1,3,4-oxadiazole ring, a 1,2,4-oxadiazole ring, a 1,2,5-oxadiazole ring,
  • the rings described above may have substituents and in a case where they have two or more substituents, the substituents may be identical or different from each other.
  • substituents can include a halogen atom, an alkyl group, an aryl group, a carbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a carbamoyl group, a sulfamoyl group, a cyano group, an alkylsulfonyl group, an arylsulfonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, and an acyl group.
  • substituents are groups capable of substitution, they may have further substituents and examples of preferred substituents can include a halogen atom, an alkyl group, an aryl group, a carbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, a cyano group, a sulfamoyl group, an alkylsulfonyl group, an arylsulfonyl group, and an acyloxy group.
  • a halogen atom an alkyl group, an aryl group, a carbonamide group, an alkylsulfonamide group, an arylsulfonamide group, an alkoxy group, an aryloxy group, an alkylthi
  • the carbamoyl group represented by Q 2 is a carbamoyl group preferably having 1 to 50 carbon atoms and, more preferably, having 6 to 40 carbon atoms, and examples can include unsubstituted carbamoyl, methyl carbamoyl, 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)carbamo
  • the acyl group represented by Q 2 is an acyl group, preferably having 1 to 50 carbon atoms and, more preferably having 6 to 40 carbon atoms and can include, for example, formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2-hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, benzoyl, 4-dodecyloxybenzoyl, and 2-hydroxymethylbenzoyl.
  • the alkoxycarbonyl group represented by Q 2 is an alkoxycarbonyl group, preferably having 2 to 50 carbon atoms and, more preferably, having 6 to 40 carbon atoms and can include, for example, methoxycarbonyl, ethoxycarbonyl, isobutyloxycarbonyl, cyclohexyloxycarbonyl, dodecyloxycarbonyl, and benzyloxycarbonyl.
  • the aryloxy carbonyl group represented by Q 2 is an aryloxycarbonyl group, preferably having 7 to 50 carbon atoms and, more preferably having 7 to 40 carbon atoms, and can include, for example, phenoxycarbonyl, 4-octyloxyphenoxycarbonyl, 2-hydroxymethylphenoxycarbonyl, and 4-dodecyloxyphenoxycarbonyl.
  • the sulfonyl group represented by Q 2 is a sulfonyl group, preferably having 1 to 50 carbon atoms and, more preferably having 6 to 40 carbon atoms, and can include, for example, methylsulfonyl, butylsulfonyl, octylsulfonyl, 2-hexadecylsulfonyl, 3-dodecyloxypropylsulfonyl, 2-octyloxy-5-tert-octylphenyl sulfonyl, and 4-dodecyloxyphenyl sulfonyl.
  • the sulfamoyl group represented by Q 2 is a sulfamoyl group, preferably having 0 to 50 carbon atoms and, more preferably having 6 to 40 carbon atoms, and can include, for example, unsubstituted sulfamoyl, N-ethylsulfamoyl group, N-(2-ethylhexyl)sulfamoyl, N-decylsulfamoyl, N-hexadecylsulfamoyl, N- ⁇ 3-(2-ethylhexyloxy)propyl ⁇ sulfamoyl, N-(2-chloro-5-dodecyloxycarbonylphenyl)sulfamoyl, and N-(2-tetradecyloxyphenyl)sulfamoyl.
  • the group represented by Q 2 may further have a group mentioned as the example of the substituent of 5 to 7-membered unsaturated ring represented by Q 1 at the position capable of substitution. In a case where the group has two or more substituents, such substituents may be the same or different from each other.
  • a 5 or 6-membered unsaturated ring is preferred for Q 1 , and a benzene ring, a pyrimidine ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a 1,3,4-thiadiazole ring, a 1,2,4-thiadiazole ring, a 1,3,4-oxadiazole ring, a 1,2,4-oxadiazole ring, a thioazole ring, an oxazole ring, an isothiazole ring, an isooxazole ring, and a ring in which the ring described above is condensed with a benzene ring or unsaturated hetero ring are further preferred.
  • Q 2 is preferably a carbamoyl group and, particularly, a carbamoyl group having a hydrogen atom on
  • R 1 represents one selected from an alkyl group, an acyl group, an acylamino group, a sulfonamide group, an alkoxycarbonyl group, and a carbamoyl group.
  • R 2 represents one selected from a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acyloxy group, and a carbonate ester group.
  • R 3 and R 4 each independently represent a group capable of substituting for a hydrpgen atom on a benzene ring which is mentioned as the example of the substituent for formula (A-1).
  • R 3 and R 4 may link together 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, or the like), an acylamino group (for example, an acetylamino group, a benzoylamino group, a methylureido group, a 4-cyanophenylureido group, or the like), or a carbamoyl group (for example, a n-butylcarbamoyl group, an N,N-diethylcarbamoyl group, a phenylcarbamoyl group, a 2-chlorophenylcarbamoyl group, a 2,4-dichlorophenylcarbamoyl group, or the like).
  • An acylamino group including a urei
  • 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, or the like), or an aryloxy group (for example, a phenoxy group, a naphthoxy group, or the like).
  • 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, or the like
  • an aryloxy group for example, a phenoxy group, a naphthoxy group, or the like.
  • 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, and more preferably an alkyl group or an acylamino group. Examples of the preferred substituent thereof are similar to those for R 1 . In the case where R 4 is an acylamino group, R 4 may preferably link with R 3 to form a carbostyryl ring.
  • R 3 and R 4 in formula (A-2) link together to form a condensed ring
  • a naphthalene ring is particularly preferred as the condensed ring.
  • the same substituent as the example of the substituent referred to for formula (A-1) may bond to the naphthalene ring.
  • R 1 is preferably a carbamoyl group. Among them, a benzoyl group is particularly preferred.
  • R 2 is preferably an alkoxy group or an aryloxy group and, particularly preferably an alkoxy group.
  • the reducing agent in the case where the reducing agent has an aromatic hydroxy group (-OH) or an amino group (-NHR, R represents a hydrogen atom or an alkyl group), particularly in the case where the reducing agent is a bisphenol described above, it is preferred to use in combination, a nonreducing compound having a group capable of reacting with these groups, and that is also capable of forming a hydrogen bond therewith.
  • a group forming a hydrogen bond with a hydroxy group or an amino group there can be mentioned a phosphoryl group, a sulfoxide group, a sulfonyl group, a carbonyl group, an amide group, an ester group, a urethane group, a ureido group, a tertiary amino group, a nitrogen-containing aromatic group, and the like.
  • Particularly preferred among them is a phosphoryl group, a sulfoxide group, an amide group (not having >N-H moiety but being blocked in the form of >N-Ra (where, Ra represents a substituent other than H)), a urethane group (not having >N-H moiety but being blocked in the form of >N-Ra (where, Ra represents a substituent other than H)), and a ureido group (not having >N-H moiety but being blocked in the form of >N-Ra (where, Ra represents a substituent other than H)).
  • R 21 to R 23 each independently represent one selected from an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, and a heterocyclic group, which may be substituted or unsubstituted.
  • R 21 to R 23 contain a substituent
  • substituents include a halogen atom, an alkyl group, an aryl group, an alkoxy group, an amino group, an acyl group, an acylamino group, an alkylthio group, an arylthio group, a sulfonamide group, an acyloxy group, an oxycarbonyl group, a carbamoyl group, a sulfamoyl group, a sulfonyl group, a phosphoryl group, and the like, in which preferred as the substituents are an alkyl group or an aryl group, e.g., a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a t-octyl group, a phenyl group, a 4-alkoxyphenyl group, a 4-acyloxyphenyl group, and the like.
  • an alkyl group expressed by R 21 to R 23 include a methyl group, an ethyl group, a butyl group, an octyl group, a dodecyl group, an isopropyl group, a t-butyl group, a t-amyl group, a t-octyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a benzyl group, a phenetyl group, a 2-phenoxypropyl group, and the like.
  • aryl group there can be mentioned a phenyl group, a cresyl group, a xylyl group, a naphthyl group, a 4-t-butylphenyl group, a 4-t-octylphenyl group, a 4-anisidyl group, a 3,5-dichlorophenyl group, and the like.
  • alkoxyl group there can be mentioned a methoxy group, an ethoxy group, a butoxy group, an octyloxy group, a 2-ethylhexyloxy group, a 3,5,5-trimethylhexyloxy group, a dodecyloxy group, a cyclohexyloxy group, a 4-methylcyclohexyloxy group, a benzyloxy group, and the like.
  • aryloxy group there can be mentioned a phenoxy group, a cresyloxy group, an isopropylphenoxy group, a 4-t-butylphenoxy group, a naphthoxy group, a biphenyloxy group, and the like.
  • an amino group there can be mentioned are a dimethylamino group, a diethylamino group, a dibutylamino group, a dioctylamino group, an N-methyl-N-hexylamino group, a dicyclohexylamino group, a diphenylamino group, an N-methyl-N-phenylamino group, and the like.
  • R 21 to R 23 is an alkyl group, an aryl group, an alkoxy group, or an aryloxy group. Concerning the effect of the invention, it is preferred that at least one or more of R 21 to R 23 are an alkyl group or an aryl group, and more preferably, two or more of them are an alkyl group or an aryl group. From the viewpoint of low cost availability, it is preferred that R 21 to R 23 are of the same group.
  • the compound expressed by formula (D) used in the invention can be used in the photothermographic material by being incorporated into the coating solution in the form of solution, emulsion dispersion, or solid fine particle dispersion, similar to the case of reducing agent. However, it is preferred to use the compound in the form of solid dispersion.
  • the compound expressed by formula (D) forms a hydrogen-bonded complex with a compound having a phenolic hydroxy group or an amino group, and can be isolated as a complex in crystalline state depending on the combination of the reducing agent and the compound expressed by formula (D).
  • crystal powder thus isolated in the form of solid fine particle dispersion, because it provides stable performance. Further, it is also preferred to use a method of leading to form complex during dispersion by mixing the reducing agent and the compound expressed by formula (D) in the form of powders and dispersing them with a proper dispersion agent using sand grinder mill or the like.
  • the compound expressed by formula (D) is preferably used in a range from 1 mol% to 200 mol%, more preferably from 10 mol% to 150 mol%, and further preferably, from 20 mol% to 100 mol%, with respect to the reducing agent.
  • the photosensitive silver halide of the present invention has an average silver iodide content of 40 mol% or higher, and at least 50% of a projected area of total grains of the photosensitive silver halide is occupied by tabular grains having an aspect ratio of 2 or more.
  • the photothermographic material contains a compound which substantially reduces visible light absorption by photosensitive silver halide after thermal development versus before thermal development.
  • a silver iodide complex-forming agent is used as the compound which substantially reduces visible light absorption by photosensitive silver halide after thermal development.
  • the silver iodide complex-forming agent As for the silver iodide complex-forming agent according to the present invention, at least one of a nitrogen atom or a sulfur atom in the compound can contribute to a Lewis acid-base reaction which gives an electron to a silver ion, as a ligand atom (electron donor: Lewis base).
  • the stability of the complex is defined by successive stability constant or total stability constant, but it depends on the combination of silver ion, iodo ion and the silver complex forming agent. As a general guide, it is possible to obtain a large stability constant by a chelate effect from intramolecular chelate ring formation, by means of increasing the acid-base dissociation constant and the like.
  • the ultra violet-visible light absorption spectrum of the photosensitive silver halide can be measured by a transmission method or a reflection method.
  • the ultra violet-visible light absorption spectrum of photosensitive silver halide can be observed by using, independently or in combination, the means of difference spectrum and removal of other compounds by solvent and the like.
  • a 5 to 7-membered heterocyclic compound containing at least one nitrogen atom is preferable.
  • the said 5 to 7-membered nitrogen-containing heterocycle may be saturated or unsaturated, and may have another substituent.
  • the substituent on a heterocycle may bind to each other to form a ring.
  • pyridine, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, indole, isoindole, indolizine, quinoline, isoquinoline, benzimidazole, 1H-imidazole, quinoxaline, quinazoline, cinnoline, phthalazine, 1,8-naphthylizine, 1,10-phenanthroline, benzotriazole, 1,2,4-triazine, 1,3,5-triazine, and the like can be described.
  • pyridine imidazole, pyrazine, pyrimidine, pyridazine, phtharazine, triazine, 1,8-naphthylizine, 1,10-phenanthroline, and the like can be described.
  • a halogen atom fluorine atom, chlorine atom, bromine atom, or iodine atom
  • an alkyl group a straight, a branched, a cyclic alkyl group containing a bicycloalkyl group and an active methine group
  • an alkenyl group an alkynyl group, an aryl group, a heterocyclic group (substituted position is not asked)
  • an acyl group an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an N-acylcarbamoyl group, an N-sulfonylcarbamoyl group, an N-carbamoylcarbamoyl group, an N-sulfamoylcarbamoyl group
  • an active methine group means a methine group substituted by two electron-attracting groups, wherein the electron-attracting group means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, a carbonimidoyl group.
  • two electron-attracting groups may bind each other to form a cyclic structure.
  • the salt means a salt formed with positive ion such as an alkaline metal, an alkaline earth metal, a heavy metal, or the like, or organic positive ion such as an ammonium ion, a phosphonium ion, or the like. These substituents may be further substituted by these substituents.
  • heterocycles may be further condensed by another ring.
  • the substituent is an anion group (e.g., -CO 2 - , -SO 3 - , -S - , or the like)
  • the heterocycle containing nitrogen atom of the invention may become a positive ion (e.g., pyridinium, 1,2,4-triazolium, or the like) and may form an intramolecular salt.
  • the acid dissociation constant (pKa) of a conjugated acid of nitrogen-containing heterocyclic part in acid dissociation equilibrium of the said compound is preferably 3 to 8 in the mixture solution of tetrahydrofuran/water (3/2) at 25°C, and more preferably, the pKa is 4 to 7.
  • heterocyclic compound pyridine, pyridazine, or phtharazine derivative is preferable, and particularly preferable is pyridine or phthalazine derivative.
  • heterocyclic compounds have a mercapto group, a sulfide group or a thione group as the substituent
  • pyridine, thiazole, isothiazole, oxazole, isoxazole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, triazine, triazole, thiadiazole, and oxadiazole derivatives are preferable
  • thiazole, imidazole, pyrazole, pyrazine, pyrimidine, pyridazine, triazine, and triazole derivatives are particularly preferable.
  • R 11 and R 12 each independently represent a hydrogen atom or a substituent.
  • R 21 and R 22 each independently represent a hydrogen atom or a substituent. However, both of R 11 and R 12 are not hydrogen atoms simultaneously and both of R 21 and R 22 are not hydrogen atoms simultaneously.
  • the substituent herein the substituent explained as the substituent of a 5 to 7-membered nitrogen-containing heterocyclic type silver iodide complex-forming agent mentioned above can be described.
  • R 31 to R 35 each independently represent a hydrogen atom or a substituent.
  • the substituent represented by R 31 to R 35 the substituent of a 5 to 7-membered nitrogen-containing heterocyclic type silver iodide complex-forming agent mentioned above can be used.
  • preferred substituting position is R 32 to R 34 .
  • R 31 to R 35 may bind each other to form a saturated or an unsaturated ring.
  • a preferred substituent is a halogen atom, an alkyl group, an aryl group, a carbamoyl group, a hydroxy group, an alkoxy group, an aryloxy group, a carbamoyloxy group, an amino group, an acylamino group, a ureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, or the like.
  • the acid dissociation constant (pKa) of conjugated acid of pyridine ring part preferably is 3 to 8 in the mixed solution of tetrahydrofuran /water (3/2) at 25°C, and particularly preferably 4 to 7.
  • R 41 to R 44 each independently represent a hydrogen atom or a substituent.
  • R 41 to R 44 may bind each other to form a saturated or an unsaturated ring.
  • the substituent represented by R 41 to R 44 the substituent of a 5 to 7-membered nitrogen-containing heterocyclic type silver iodide complex-forming agent mentioned above can be described.
  • an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a hydroxy group, an alkoxy group, an aryloxy group a heterocyclic oxy group, and a group which forms a phthalazine ring by benzo-condensation are described.
  • a hydroxy group exists at the carbon atom adjacent to nitrogen atom of the compound represented by formula (4), there exists equilibrium between pyridazinone.
  • the compound represented by formula (4) more preferably forms a phthalazine ring represented by the following formula (5), and furthermore, this phthalazine ring particularly preferably has at least one subsutituent.
  • R 51 to R 56 in formula (5) the substituent of a 5 to 7-membered nitrogen-containing heterocyclic type silver iodide complex-forming agent mentioned above can be described.
  • an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a hydroxy group, an alkoxy group, an aryloxy group, and the like are described.
  • An alkyl group, an alkenyl group, an aryl group, an alkoxy group, and an aryloxy group are preferable and an alkyl group, an alkoxy group, and an aryloxy group are more preferable.
  • R 61 to R 63 each independently represent a hydrogen atom or a substituent.
  • R 62 the substituent of a 5 to 7-membered nitrogen-containing heterocyclic type silver iodide complex-forming agent mentioned above can be described.
  • R 71 and R 72 each independently represent a hydrogen atom or a substituent.
  • L represents a divalent linking group.
  • n represents 0 or 1.
  • an alkyl group (containing a cycloalkyl group), an alkenyl group (containing a cycloalkenyl group), an alkynyl group, an aryl group, a heterocyclic group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an imide group, and a complex substituent containing these groups are described as examples.
  • a divalent linking group represented by L preferably has the length of 1 to 6 atoms and more preferably has the length of 1 to 3 atoms, and furthermore, may have a substituent.
  • One more of the compounds preferably used is a compound represented by formula (8).
  • R 81 to R 84 each independently represent a hydrogen atom or a substituent.
  • substituent represented by R 81 to R 84 an alkyl group (including a cycloalkyl group), an alkenyl group (including a cycloalkenyl group), an alkynyl group, an aryl group, a heterocyclic group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an imide group, and the like are described as examples.
  • the compounds represented by formulae (3), (4), (5), (6) and (7) are more preferable and, the compounds represented by formulae (3) and (5) are particularly preferable.
  • silver iodide complex-forming agent Preferable examples of silver iodide complex-forming agent are described below, however the present invention is not limited in these.
  • the silver iodide complex-forming agent according to the present invention can also be a compound common to a toner, in the case where the agent achieves the function of conventionally known toner.
  • the silver iodide complex-forming agent according to the present invention can be used in combination with a toner. And, two or more kinds of the silver iodide complex-forming agents may be used in combination.
  • the silver iodide complex-forming agent according to the present invention preferably exists in a film under the state separated from a photosensitive silver halide, such as a solid state. It is also preferably added to the layer adjacent to the image forming layer. Concerning the silver iodide complex-forming agent according to the present invention, a melting point of the compound is preferably adjusted to a suitable range so that it can be dissolved when heated at thermal developing temperature.
  • an absorption intensity of ultra violet-visible light absorption spectrum of photosensitive silver halide after thermal development preferably becomes 80% or less as compared with before thermal development, more preferably 40% or less and, particularly preferably 10% or less.
  • the silver iodide complex-forming agent according to the invention may be incorporated into a photothermographic material by being added into the coating solution, such as in the form of a solution, an emulsion dispersion, a solid fine particle dispersion, or the like.
  • Well known emulsion dispersing methods include a method comprising dissolving the silver iodide complex-forming agent in an oil such as dibutylphthalate, tricresylphosphate, glyceryl triacetate, diethylphthalate, or the like, and an auxiliary solvent such as ethyl acetate, cyclohexanone, or the like, followed by mechanically forming an emulsified dispersion.
  • an oil such as dibutylphthalate, tricresylphosphate, glyceryl triacetate, diethylphthalate, or the like
  • an auxiliary solvent such as ethyl acetate, cyclohexanone, or the like
  • Solid fine particle dispersing methods include a method comprising dispersing the powder of the silver iodide complex-forming agent according to the invention in a proper solvent such as water or the like, by means of ball mill, colloid mill, vibrating ball mill, sand mill, jet mill, roller mill, or ultrasonics, thereby obtaining a solid dispersion.
  • a protective colloid such as polyvinyl alcohol
  • a surfactant for instance, an anionic surfactant such as sodium triisopropylnaphthalenesulfonate (a mixture of compounds having the three isopropyl groups in different substitution sites)).
  • the dispersion media In the mills enumerated above, generally used as the dispersion media are beads made of zirconia and the like, and Zr and the like eluting from the beads may be incorporated in the dispersion.
  • the amount of Zr and the like generally incorporated in the dispersion is in a range of from 1 ppm to 1000 ppm. It is practically acceptable so long as Zr is incorporated in the photothermographic material in an amount of 0.5 mg or less per 1 g of silver.
  • an antiseptic for instance, benzisothiazolinone sodium salt
  • an antiseptic for instance, benzisothiazolinone sodium salt
  • the silver iodide complex-forming agent according to the invention is preferably used in the form of a solid dispersion.
  • the silver iodide complex-forming agent according to the invention is preferably used in the range from 1 mol% to 5000 mol%, more preferably, from 10 mol% to 1000 mol% and, further preferably, from 50 mol% to 300 mol%, with respect to the photosensitive silver halide in each case.
  • 50% by weight or more of the binder used for the image forming layer of the present invention is formed by a polymer latex containing a monomer component represented by the following formula (M) within a range of from 10% by weight to 70% by weight.
  • an alkyl group having 1 to 4 carbon atoms is preferred, and more preferably an alkyl group having 1 to 2 carbon atoms is used.
  • a halogen atom a fluorine atom, a chlorine atom, or a bromine atom is preferred, and more preferred is a chlorine atom.
  • one of R 01 and R 02 represents a hydrogen atom and the other represents a methyl group or a chlorine atom.
  • monomer represented by the above formula (M) of the present invention include 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 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, and 2-cyano-1,3-butadiene.
  • the binder of the present invention are polymers obtained by copolymerizing monomers represented by formula (M), where the copolymerization ratio of the monomer represented by formula (M) for the polymer is in a range of from 10% by weight to 70% by weight, preferably from 15% by weight to 65% by weight, and more preferably from 20% by weight to 60% by weight.
  • the other monomers which are capable to copolymerize with the monomer represented by formula (M), are not particularly restricted, and any monomers may be preferably used provided that they are polymerizable by usual radical polymerization or ion polymerization.
  • the monomer which can be used preferably, it is capable to select the combination independently and freely from the monomer groups (a) to (j) described below. -Monomer groups (a) to (j)-
  • Preferred examples of a polymer copolymerized with the monomer represented by formula (M) of the present invention include copolymers with styrene (for example, random copolymer, block polymer, or the like), copolymers with styrene and butadiene (for example, random copolymer, butadiene-isoprene-styrene block copolymer, styrene-butadiene-isoprene-styrene block copolymer, or the like), copolymers with ethylene and propylene, copolymers with acrylonitrile, copolymers with isobutyrene, copolymers with acrylic esters (for example, as acrylic ester, ethyl acrylate, butyl acrylate, or the like can be used), and copolymers with acrylic ester and acrylonitrile (the same acrylic esters as mentioned above can be used).
  • styrene for example, random cop
  • the polymer of the present invention is preferably copolymerized with a monomer having an acid group.
  • a monomer having an acid group preferred are a carboxylic acid, a sulfonic acid, and a phosphoric acid.
  • the copolymerization ratio of a monomer having the acid group is preferably in a range of from 1% by weight to 20% by weight, and more preferably from 1% by weight to 10% by weight.
  • Examples of a monomer having the acid group include acylic acid, methacrylic acid, itaconic acid, p-styrene sulfonic acid sodium salt, isopyrene sulfonic acid, phoshoryl ethyl methacrylate, and the like. Any kind of polymer may be used in combination with the polymer copolymerized with the monomer represented by formula (M) as the binder of the invention.
  • Suitable as the polymer which can be used in combination are those that are transparent or translucent, and that are generally colorless, such as natural resin or polymer and their copolymers; synthetic resin or polymer and their copolymer; or media forming a film; for example, included are gelatin, rubber, poly(vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetate butyrate, poly(vinyl pyrrolidone), casein, starch, poly(acrylic acid), poly(methylmethacrylic acid), poly(vinyl chloride), poly(methacrylic acid), styrene-maleic anhydride copolymers, styreneacrylonitrile copolymers, styrene-butadiene copolymers, poly(vinyl acetal) (e.g., poly(vinyl formal) or poly(vinyl butyral)), polyester, polyurethane, phenoxy resin, poly(vinylidene chloride),
  • the binder of the invention preferably has a grass transition temperature (Tg) in a range of -30°C to 70°C, more preferably -10°C to 50°C, and further preferably 0°C to 40°C, considering work brittleness and image storability.
  • Tg grass transition temperature
  • Two or more kinds of polymers can be blended for the binder, and in this case, Tg of the blended polymer as a composition weighed average preferably falls within the range above.
  • Tg of each phase preferably falls within the range above.
  • Tgi is the glass transition temperature (absolute temperature) of the homopolymer obtained with the ith monomer.
  • Values for the glass transition temperature (Tgi) of the homopolymers derived from each of the monomers were obtained from J. Brandrup and E. H. Immergut, Polymer Handbook (3rd Edition) (Wiley-Interscience, 1989).
  • the polymer used in the invention can be readily obtained by a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, an anionic polymerization method, a cationic polymerization method, or the like, however most preferable is an emulsion polymerization method by which polymer can be obtained as a latex.
  • the polymer latex is obtained by emulsion polymerization at about 30°C to 100°C, preferably at 60°C to 90°C, for 3 hours to 24 hours with stirring using water or a mixed solvent of water and a water-miscible organic solvent (for example, methanol, ethanol, acetone, or the like) as a dispersion medium, and using a monomer mixture in an amount of 5% by weight to 150% by weight with respect to the dispersion solvent, an emulsifying agent in an amount of 0.1 % by weight to 20% by weight with respect to a total amount of monomers, and a polymerization initiator.
  • a water-miscible organic solvent for example, methanol, ethanol, acetone, or the like
  • Conditions such as the dispersion medium, monomer concentration, the amount of the initiator, the amount of the emulsifying agent, the amount of the dispersing agent, the reaction temperature and the addition method of the monomer may be appropriately determined considering the kind of the monomer used.
  • the dispersing agent is preferably used, if necessary.
  • Emulsion polymerization is usually carried out according to the following documents: "Gosei Jushi Emulsion (Synthetic Resin Emulsion)” ed. by Taira Okuda and Hiroshi Inagaki, Polymer Publishing Association (1978); “Gosei Latex no Oyo (Application of Synthetic Latex)” ed. by Taka-aki Sugimura, Yasuo Kataoka, Soichi Suzuki and Keiji Kasahara, Polymer Publishing Association (1993); and “Gosei Latex no Kagaku (Chemistry of Synthetic Latex)" by Soichi Muroi, Polymer Publishing Association (1970).
  • Emulsion polymerization method for synthesizing the polymer latex of the invention may be selected from an overall polymerization method, a monomer addition (continuous or divided) method, an emulsion addition method and a seed polymerization method.
  • the overall polymerization method, monomer addition (continuous or divided) method, and emulsion addition method are preferable in view of productivity of the latex.
  • the polymerization initiator described above may have a radical generation ability, and examples of them available include inorganic peroxides such as persulfate salts and hydrogen peroxide, peroxides described in the catalogue of organic peroxides by Nippon Oil and Fat Co., and azo compounds described in azo polymerization initiator catalogue by Wako Pure Chemical Industries, Ltd. Among them, a water-soluble peroxides such as persulfate, and water-soluble azo compounds described in azo polymerization initiator catalogue by Wako Pure Chemical Industries, Ltd., are preferable.
  • Ammonium persulfate, sodium persulfate, potassium persulfate, azobis(2-methylpropionamidine) hydrochloride, azobis(2-methyl-N-(2-hydroxyethyl)propionamide and azobiscyanovaleric acid are more preferable, and particularly, peroxides such as ammonium persulfate, sodium persulfate and potassium persulfate are preferable from the viewpoint of image storability, solubility, and cost.
  • the addition amount of the polymerization initiator described above is preferably in a range from 0.3% by weight to 2.0% by weight, more preferably 0.4% by weight to 1.75% by weight, and particularly preferably 0.5% by weight to 1.5% by weight, based on a total amount of monomers.
  • Image storability decreases when the amount of the polymerization initiator is less than 0.3% by weight, while the latex tends to be aggregated to deteriorate coating ability when the amount of the polymerization initiator exceeds 2.0% by weight.
  • any surfactants such as an anionic surfactant, a nonionic surfactant, a cationic surfactant, or an amphoteric surfactant can be employed.
  • An anionic surfactant is preferably employed from the viewpoint of dispersibility and image storability, and more preferred is a sulfonic acid-type anionic surfactant which maintains the polymerization stability even in a small amount and has a hydrolysis resistance.
  • a sulfonic acid-type surfactant is preferably used in a rage of from 0.1% by weight to 10.0% by weight based on the total amount of monomers, more preferably from 0.2% by weight to 7.5% by weight, and particularly preferably from 0.3% by weight to 5.0% by weight. Stability in the emulsion polymerization process can not secure when the addition amount of the polymerization emulsifying agent is less than 0.1% by weight, while image storability decreases when the addition amount exceeds 10.0 % by weight.
  • Chelating agents are preferably used for the synthesis of the polymer latex used in the invention.
  • the chelating agent is a compound capable of coordinating multi-valent metal ions such as iron ion, and alkali earth metal ions such as calcium ion, and examples thereof include the compounds described in JP-B No. 6-8956; USP No. 5053322; and JP-A Nos.
  • 4-73645 4-127145, 4-247073, 4-305572, 6-11805, 5-173312, 5-66527, 5-158195, 6-118580, 6-110168, 6-161054, 6-175299, 6-214352, 7-114161, 7-114154, 7-120894, 7-199433, 7-306504, 9-43792, 8-314090, 10-182571, 10-182570, and 11-190892.
  • the chelating agent used in the invention is preferably an inorganic chelating compound (sodium tripolyphosphate, sodium hexametaphosphate, sodium tetrapolyphosphate, or the like), an aminopolycarboxylic acid chelating compound (nitrilotriacetic acid, ethylenediamine tetraacetic acid, or the like), an organic phosphonic acid chelating agent (compounds described in Research Disclosure No. 18170, JP-A Nos.
  • an inorganic chelating compound sodium tripolyphosphate, sodium hexametaphosphate, sodium tetrapolyphosphate, or the like
  • an aminopolycarboxylic acid chelating compound nitrilotriacetic acid, ethylenediamine tetraacetic acid, or the like
  • organic phosphonic acid chelating agent compounds described in Research Disclosure No. 18170, JP-A Nos.
  • aminopolycarboxylic acid derivative Preferable examples of the aminopolycarboxylic acid derivative are described in the supplement table of "EDTA (-Chemistry of Complexane-)", Nankodo 1977.
  • a part of the carboxyl group of these compounds may be substituted by a salt of alkali metal such as sodium or potassium, or an ammonium salt.
  • aminocarboxylic acid derivatives include iminodiacetic acid, N-methyliminodiacetic acid, N-(2-aminoethyl)iminodiacetic acid, N-(carbamoylethyl)iminodiacetic acid, nitrilotriacetic acid, ehylenediamine-N,N'-diacetic acid, ehylenediamine-N,N'-di- ⁇ -propionic acid, ethylenediamine-N,N'-di- ⁇ -propionic acid, N,N'-ethylene-bis( ⁇ -o-hydroxyphenyl)glycine, N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, ethylenediamine-N,N'-diacetic acid-N,N'-diacetohydroxamic acid, N-hydroxyethylethylenediamine-N,N',N'-triacetic acid,
  • the addition amount of the chelating agent described above is preferable 0.01% by weight to 0.4% by weight, more preferably 0.02% by weight to 0.3% by weight, and particularly preferably 0.03% by weight to 0.15% by weight based on a total amount of monomers.
  • Metal ions mingling in the production process of the polymer latex are insufficiently trapped when the amount of the chelating agent is less than 0.01% by weight to decrease stability of the latex against aggregation to deteriorate coating ability.
  • the content exceeds 0.4%, on the other hand, the viscosity of the latex increases to deteriorate coating ability.
  • the chain transfer agent is preferably used in the synthesis of the polymer latex used in the invention.
  • the compounds described in Polymer Handbook Third Edition (Wiley-Interscience, 1989) are preferable as the chain transfer agents. Sulfur compounds are preferable since they have high chain transfer ability to make the amount of use of the reagent small.
  • Particularly preferable chain reaction agents are hydrophobic mercaptan chain transfer agents such as tert-dodecylmercaptan, n-dodecylmercaptan, and the like.
  • the amount of the chain transfer agent described above is preferable 0.2% by weight to 2.0% by weight, more preferably 0.3% by weight to 1.8% by weight, and particularly preferably 0.4% by weight to 1.6% by weight based on a total amount of monomers. Work brittleness is decreased when the amount of the chain transfer agent is less than 0.2% by weight, while image storability is deteriorated when the amount exceeds 2.0% by weight.
  • additives such as an electrolyte, a stabilizer, a thickener, a defoaming agent, an antioxidant, a vulcanizing agent, an antifreeze agent, a gelling agent, vulcanization accelerator, and the like described in Synthetic Rubber Handbook and the like may be used in addition to the compounds above.
  • x, y, z, and z' in chemical formula show the mass ratios in the polymer composition, and the sum of x, y, z, and z' is equal to 100%.
  • Tg represents the glass transition temperature of a dry film obtained from the polymer.
  • the mixture was heated to 90°C with stirring for 3 hours. After the reaction was completed, the inner temperature of the reaction vessel was cooled to room temperature.
  • the polymer obtained was filtered through a filter cloth (mesh: 225), then 1145 g of the example compound P-1 (solid content of 45 % by weight, particle diameter of 112 nm) was obtained.
  • water solvent for the solvent of a coating solution for the polymer latex, water solvent can be used and any of water-admixing organic solvents may be used in combination.
  • organic solvents there can be used, for example, alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and the like; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and the like; ethyl acetate, dimethylformamide, and the like.
  • the addition amount of the organic solvent is 50% by weight or less, and more preferably 30% by weight or less, with respect to the solvent.
  • the concentration of the polymer is preferably 10% by weight to 70% by weight, more preferably 20% by weight to 60% by weight, and particularly preferably 30% by weight to 55% by weight, with respect to the latex solution in each case.
  • the equilibrium water content under 25°C and 60%RH is preferably 2% by weight or lower, but is more preferably, 0.01% by weight to 1.5% by weight, and is further preferably, 0.02% by weight to 1.0% by weight.
  • polymers capable of being dispersed in an aqueous solvent are particularly preferable.
  • dispersed states may include a latex, in which water-insoluble fine particles of hydrophobic polymer are dispersed, or such in which polymer molecules are dispersed in molecular states or by forming micelles, but preferred are latex-dispersed particles.
  • the average particle size of the latex-dispersed particles is in a range of from 1 nm to 50,000 nm, preferably from 5 nm to 1,000 nm, more preferably 10 nm to 500 nm, and further preferably 50 nm to 200 nm.
  • particle size distribution of the dispersed particles there is no particular limitation concerning particle size distribution of the dispersed particles, and they may be widely distributed or may exhibit a monodisperse particle size distribution. From the viewpoint of controlling the physical properties of the coating solution, preferred mode of usage includes mixing two or more types of particles each having monodisperse particle distribution.
  • hydrophilic polymers such as gelatin, polyvinyl alcohol, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and the like.
  • the hydrophilic polymers above are added at an amount of 30% by weight or less, preferably 20% by weight or less, with respect to the total weight of the binder incorporated in the image forming layer.
  • the image forming layer of the present invention is preferably formed by using a polymer latex.
  • the weight ratio for total binder to organic silver salt is preferably in a range of from 1/10 to 10/1, more preferably from 1/3 to 5/1, and further preferably 1/1 to 3/1.
  • the weight ratio for total binder to photosensitive silver halide is preferably in a range of from 400 to 5, and more preferably, from 200 to 10.
  • the total amount of binder in the image forming layer of the invention is preferably in a range from 0.2 g/m 2 to 30 g/m 2 , more preferably from 1 g/m 2 to 15 g/m 2 , and further preferably 2 g/m 2 to 10 g/m 2 .
  • a crosslinking agent for crosslinking or a surfactant and the like to improve coating properties.
  • antifoggant As an antifoggant, stabilizer and stabilizer precursor usable in the invention, there can be mentioned those disclosed as patents in paragraph number 0070 of JP-A No. 10-62899 and in line 57 of page 20 to line 7 of page 21 of EP-A No. 0803764A1, the compounds described in JP-A Nos. 9-281637 and 9-329864, in USP No. 6,083,681, and in EP-A No. 1048975.
  • the antifoggant preferably used in the invention is an organic halogen compound, and those disclosed in paragraph Nos. 0111 to 0112 of JP-A No. 11-65021 can be enumerated as examples thereof.
  • the organic halogen compound expressed by formula (P) in JP-A No. 2000-284399 the organic polyhalogen compound expressed by formula (II) in JP-A No. 10-339934, and organic polyhalogen compounds described in JP-A Nos. 2001-31644 and 2001-33911 are preferred.
  • Q represents one selected from an alkyl group, an aryl group, and a heterocyclic group
  • Y represents a divalent linking group
  • n represents 0 or 1
  • Z 1 and Z 2 each represent a halogen atom
  • X represents a hydrogen atom or an electron-attracting group.
  • Q is preferably an aryl group, or a heterocyclic group.
  • Q is preferably a nitrogen-containing heterocyclic group having 1 or 2 nitrogen atoms, and particularly preferably a 2-pyridyl group or a 2-quinolyl group.
  • Q in the case where Q is an aryl group, Q preferably is a phenyl group substituted by an electron-attracting group whose Hammett substituent coefficient ⁇ p yields a positive value.
  • Hammett substituent coefficient reference can be made to Journal of Medicinal Chemistry, vol. 16, No. 11 (1973), pp. 1207 to 1216, and the like.
  • examples include, halogen atoms (fluorine atom ( ⁇ p value: 0.06), chlorine atom ( ⁇ p value: 0.23), bromine atom ( ⁇ p value: 0.23), iodine atom ( ⁇ p value: 0.18)), trihalomethyl groups (tribromomethyl ⁇ p value: 0.29), trichloromethyl ( ⁇ p value: 0.33), trifluoromethyl ( ⁇ p value: 0.54)), a cyano group ( ⁇ p value: 0.66), a nitro group ( ⁇ p value: 0.78), an aliphatic aryl sulfonyl goup or a heterocyclic sulfonyl group (for example, methanesulfonyl ( ⁇ p value: 0.72)), an aliphatic aryl acyl group or a heterocyclic acyl group (for example, acetyl ( ⁇ p value: 0.50) and benzoyl ( ⁇ p value: 0.43)), an alphatic atoms (
  • Preferred range of the ⁇ p value is from 0.2 to 2.0, and more preferably, from 0.4 to 1.0.
  • Particularly preferred as the electron-attracting groups are a carbamoyl group, an alkoxycarbonyl group, an alkylsulfonyl group, and an alkylphosphoryl group, and most preferred among them is a carbamoyl group.
  • X is preferably an electron-attracting group, and more preferably, a halogen atom, an aliphatic aryl sulfonyl group, a heterocyclic sulfonyl group, an aliphatic aryl acyl group, a heterocyclic acyl group, an aliphatic aryl oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, or a sulfamoyl group; particularly preferred among them is a halogen atom.
  • halogen atoms preferred are chlorine atom, bromine atom, and iodine atom; more preferred are chlorine atom and bromine atom; and particularly preferred is bromine atom.
  • n represents 0 or 1, and preferably represents 1.
  • organic polyhalogen compounds of the invention other than those above, there can be mentioned compounds disclosed in JP-A Nos. 2001-31644, 2001-56526, and 2001-209145.
  • the compounds expressed by formula (H) of the invention are preferably used in an amount of from 10 -4 mol to 1 mol, more preferably, 10 -3 mol to 0.5 mol, and further preferably, 1 ⁇ 10 -2 mol to 0.2 mol, per 1 mol of non-photosensitive silver salt incorporated in the image forming layer.
  • usable methods for incorporating the antifoggant into the photosensitive material are those described above in the method for incorporating the reducing agent.
  • the organic polyhalogen compound is also preferably used in the form of solid fine particle dispersion.
  • antifoggants there can be mentioned a mercury (II) salt described in paragraph number 0113 of JP-A No. 11-65021, benzoic acids described in paragraph number 0114 of the same literature, a salicylic acid derivative described in JP-A No. 2000-206642, a formaline scavenger compound expressed by formula (S) in JP-A No. 2000-221634, a triazine compound related to Claim 9 of JP-A No. 11-352624, a compound expressed by formula (III), 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene and the like, described in JP-A No. 6-11791.
  • a mercury (II) salt described in paragraph number 0113 of JP-A No. 11-65021
  • benzoic acids described in paragraph number 0114 of the same literature
  • a salicylic acid derivative described in JP-A No. 2000-206642
  • the photothermographic material of the invention may further contain an azolium salt in order to prevent fogging.
  • Azolium salts useful in the present invention include a compound expressed by formula (XI) described in JP-A No. 59-193447, a compound described in JP-B No. 55-12581, and a compound expressed by formula (II) in JP-A No. 60-153039.
  • the azolium salt may be added to any part of the photothermographic material, but as an additional layer, it is preferred to select a layer on the side having thereon the image forming layer, and more preferred is to select the image forming layer itself.
  • the azolium salt may be added at any time of the process of preparing the coating solution; in the case where the azolium salt is added into the image forming layer, any time of the process may be selected, from the preparation of the organic silver salt to the preparation of the coating solution, but preferred is to add the salt after preparing the organic silver salt and just before coating.
  • any method for adding the azolium salt any method using a powder, a solution, a fine-particle dispersion, and the like, may be used.
  • additives such as sensitizing agents, reducing agents, toners, and the like.
  • the azolium salt may be added at any amount, but preferably, it is added in a range from 1 ⁇ 10 -6 mol to 2 mol, and more preferably, from 1 ⁇ 10 -3 mol to 0.5 mol, per 1 mol of silver.
  • formic acid or formates as a strong fogging agent, it is preferably incorporated into the side having thereon the image forming layer containing photosensitive silver halide, at an amount of 5 mmol or less, and preferably 1 mmol or less, per 1 mol of silver.
  • Acids resulting from the hydration of diphosphorus pentaoxide, or a salt thereof include metaphosphoric acid (salt), pyrophosphoric acid (salt), orthophosphoric acid (salt), triphosphoric acid (salt), tetraphosphoric acid (salt), hexametaphosphoric acid (salt), and the like.
  • Particularly preferred acids obtainable by the hydration of diphosphorus pentaoxide or salts thereof include orthophosphoric acid (salt) and hexametaphosphoric acid (salt).
  • the salts are sodium orthophosphate, sodium dihydrogen orthophosphate, sodium hexametaphosphate, ammonium hexametaphosphate, and the like.
  • the addition amount of the acid obtained by hydration of diphoshorus pentaoxide or the salt thereof may be set as desired depending on sensitivity and fogging, but preferred is an amount of from 0.1 mg/m 2 to 500 mg/m 2 , and more preferably, from 0.5 mg/m 2 to 100 mg/m 2 .
  • the temperature for preparing the coating solution for the image forming layer of the invention is preferably from 30°C to 65°C, more preferably, from 35°C or more to less than 60°C, and further preferably, from 35°C to 55°C. Furthermore, the temperature of the coating solution for the image forming layer immediately after adding the polymer latex is preferably maintained in the temperature range from 30°C to 65°C.
  • the photothermographic material of the present invention may be either "single-sided type" having an image forming layer on one side of the support, or "double-sided type” having image forming layers on both sides of the support.
  • the black and white photothermographic material of the present invention is preferably applied for an image forming method to record radiation images using a fluorescent intensifying screen.
  • the photothermographic material can be preferably employed as described below: where the photothermographic material is exposed with a monochromatic light having the same wavelength as the main emission peak wavelength of the fluorescent intensifying screen and having a half band width of 15 ⁇ 5 nm, and after a thermal developing process, an exposure value required for a density of fog+0.5 for an image obtained by removing the image forming layer that is disposed on the opposite side of an exposure face is 0.005 Lux ⁇ sec to 0.07 Lux ⁇ sec.
  • the image forming method using the photothermographic materials described above comprises:
  • the photothermographic material used for the assembly in the present invention is subjected to X-ray exposure through a step wedge tablet and thermal development.
  • the thermal developed image may have the photographic characteristic curve where the average gamma ( ⁇ ) made at the points of a density of fog+0.1 and a density of fog+0.5 is from 0.5 to 0.9, and the average gamma ( ⁇ ) made at the points of a density of fog+1.2 and a density of fog+1.6 is from 3.2 to 4.0.
  • the use of photothermographic material having the aforesaid photographic characteristic curve would give the radiation images with excellent photographic properties that exhibit an extended bottom portion and high gamma value at a middle density area.
  • the photographic properties mentioned have the advantage of that the depiction in a low density portion on the mediastinal region and the heart shadow region having little X-ray transmittance becomes excellent, and that the density becomes easy to view, and that the contrast in the images on the lung field region having much X-ray transmittance becomes excellent.
  • the photothermographic material having the preferred photographic characteristic curve mentioned above can be easily prepared, for example, by the method where each of the image forming layer of both sides may be constituted of two or more image forming layers containing silver halide and having a sensitivity different from each other.
  • the aforesaid image forming layer preferably comprises an emulsion of high sensitivity for the upper layer and an emulsion with photographic properties of low sensitivity and high contrast for the lower layer.
  • the sensitivity difference between the silver halide emulsion in each layer is preferably from 1.5 times to 20 times, and more preferably from 2 times to 15 times.
  • the ratio of the amount of emulsion used for forming each layer may depend on the sensitivity difference between emulsions used and the covering power. Generally, as the sensitivity difference is large, the ratio of the using amount of high sensitivity emulsion is reduced. For example, if the sensitivity difference is two times, and the covering power is equal, the ratio of the amount of high sensitivity emulsion to low sensitivity emulsion would be preferably adjusted to be in a range from 1:20 to 1:50 based on silver amount.
  • the techniques such as an emulsion sensitizing method, kinds of additives and constituents employed in the production of the photothermographic material of the present invention are not particularly limited.
  • various kinds of techniques described in JP-A Nos. 2-68539, 2-103037 and 2-115837 can be applied.
  • the radiographic intensifying screen essentially comprises a support and a fluorescent substance layer coated on one side of the support as the fundamental structure.
  • the fluorescent substance layer is a layer where the fluorescent substance is dispersed in binders.
  • a transparent protective layer is generally disposed to protect the fluorescent substance layer from chemical degradation and physical shock.
  • Tungstate fluorescent substances (CaWO 4 MgWO 4 CaWO 4 :Pb and the like), terbium activated rare earth sulfoxide fluorescent substances (Y 2 O 2 S:Tb, Gd 2 O 2 S:Tb, La 2 O 2 S:Tb, (Y,Gd) 2 O 2 S:Tb, (Y,Gd)O 2 S:Tb, Tm, and the like), terbium activated rare earth phosphate fluorescent substances (YPO 4 :Tb, GdPO 4 :Tb, LaPO 4 :Tb, and the like), terbium activated rare earth oxyhalogen fluorescent substances (LaOBr:Tb, LaOBr:Tb, Tm, LaOCI:Tb, LaOCI:Tb, Tm, LaOBr:Tb, GdOBr:Tb, GdOCl:Tb, and the like), thulium activated rare earth oxyhalogen fluorescent substances (LaOBr:Tm
  • the fluorescent substances are preferably packed in the grain size graded structure.
  • fluorescent substance particles having a large particle size is preferably coated at the side of the surface protective layer and fluorescent substance particles having a small particle size is preferably coated at the side of the support.
  • the small particle size of fluorescent substance is preferably in a range from 0.5 ⁇ m to 2.0 ⁇ m and the large size is preferably in a range from 10 ⁇ m to 30 ⁇ m.
  • the single-sided type photothermographic material of the present invention is preferably applied for an X-ray photosensitive material used for mammography.
  • the method to draw the photographic characteristic curve of the photothermographic material of the present invention is explained below.
  • molybdenum target tube which emits a low pressure X-ray
  • the intensifying screen comprising substantially the fluorescent substance comprising Gd 2 O 2 S:Tb
  • the photographic characteristic curve obtained by changing the X-ray exposure value by the method of distance using the X-ray beam emitted by tungsten target tube as the beam source may give substantially the same result obtained above.
  • X-ray emitted from tungsten target tube operated by three-phase electric power supply at 50 KVp and penetrated through an aluminum plate having a thickness of 3 mm is used.
  • the commercially availabe UM-Fine screen and the photosensitive material to be measured are made contact and installed in ECMA cassette produced by Fuji Photo Film Co., Ltd.
  • the photothermographic material and the screen may be set, from X-ray tube, in turn, X-ray irradiation is performed.
  • the assembly is subjected to exposure with a step wedge tablet having a width of 0.15 in terms of log E.
  • the exposed photothermographic material is thermally developed under the determined condition. Thereafter, density is measured, and then the photographic characteristic curve is obtained where the logarithm of radiation exposure value is plotted on abscissa axis, and the optical density is plotted on ordinate axis.
  • the contrast is determined from the gradient (tan ⁇ , when the angle to the abscissa axis is ⁇ ) of the straight line connecting the points at a density of fog+0.25 and a density of fog+2.0.
  • the measuring method of the sensitivity of the photosensitive material is explained.
  • the light source a monochromatic light having the same wavelength as a main emission peak wavelength of the fluorescent intensifying screen is employed.
  • a method using the filter system where interference filters are combined can be used. According to the aforesaid method, usually the monochromic light having a required exposure value and a half band width of 15 ⁇ 5 nm can be obtained easily, although it depends also on the combination of interference filters used.
  • the monochromic light whose intensity is correctly measured by an illuminometer in advance is employed as the light source.
  • the photothermographic material is subjected to exposure with a step wedge tablet through a neutral filter for one second, where the photothermographic material and the light source are one meter apart.
  • the density is measured after a thermal developing process, the sensitivity can be obtained by determining the exposure value required to give a density of fog+0.5 and can be expressed by Lux • second.
  • Preferred sensitivity of the photothermographic material used for mammography according to the invention is 0.01 Lux ⁇ sec to 0.07 Lux ⁇ sec.
  • Preferred contrast for the photothermographic material used for mammography according to the present invention is from 3.0 to 5.0.
  • the fluorescent intensifying screen for mammography used in the invention is explained in detail below.
  • the fluorescent intensifying screen used for photographic assembly of mammography used in the present invention is required to have high image sharpness in comparison with the conventional chest diagnosis.
  • the image sharpness of commercially available fluorescent intensifying screen used for mammography is usually enhanced by coloring the fluorescent substance layer.
  • the light emitted by X-ray beam absorbed in the inner side of the fluorescent substance to the X-ray irradiation plane cannot effectively be taken out from the colored screen.
  • it is required to provide the intensifying screen coated with the amount of fluorescent substances enough to absorb X-ray and having high image sharpness without coloring the fluorescent substance layer substantially.
  • the particle size of fluorescent substances preferably may be below a fixed size.
  • the measurement of the particle size is performed by Coulter counter or observation through electron microscope.
  • the mean equivalent spherical diameter of the fluorescent substance particles is preferably in a range from 1 ⁇ m to 5 ⁇ m, and more preferably from 1 ⁇ m to 4 ⁇ m.
  • the weight ratio of binder/fluorescent substance is preferably from 1/50 to 1/20, and more preferably from 1/50 to 1/25.
  • the binder known substances described in JP-A No. 6-75097, from line 45 on right column at page 4 to line 10 on left column at page 5, can be employed.
  • the thermoplastic elastomer having a softening temperature or a melting temperature of 30°C to 150°C can be preferably used alone or in combination with the other binder polymer.
  • the proper selection of the binder used is very important to resist to the defect, because of the poor durability of the screen. It is desirable to choose entirely flexible binders as the solution for the defect. And also plasticizers and the like are preferably added in the fluorescent substance layer.
  • thermoplastic elastomer polystyrenes, polyolefines, polyurethanes, polyesters, polyamides, polybutadienes, ethylene vinyl acetates, natural rubbers, fluorinated rubbers, polyisoprenes, ethylene chlorides, styrene-butadiene rubbers, silicone rubbers, and the like can be described.
  • polyurethanes are particularly preferred.
  • the selection of the binder for the undercoat of the fluorescent substance layer is very important. Acrylate binders are preferably employed.
  • the thickness of the surface protective layer is preferably thin.
  • the preferred thickness of the surface protective layer is in a range of from 2 ⁇ m to 7 ⁇ m.
  • the materials for the surface protective layer of the screen films such as PET (especially, stretched type), PEN, nylon, and the like can be preferably stuck thereon.
  • the surface protective layer of the screen is preferably formed by coating the fluorinated resins dissolved in a suitable solvent from the standpoint of preventing stain.
  • the preferred embodiments of the fluorinated resins are described in detail in JP-A No. 6-75097, line 4 on left column at page 6 to line 43 on right column at the same page.
  • the resin suited for solvent coating type to form the surface protective layer polyurethane resins, polyacrylate resins, cellulose derivatives, polymethyl methacrylates, polyester resins, epoxy resins, and the like can be mentioned other than fluorinated resins.
  • the volume filling factor of the fluorescent substance is preferably from 60% to 80%, and more preferably from 65 % to 80%.
  • the compression processes of fluorescent substance layer described in JP-A No. 6-75097, line 29 on right column at page 4 to line 1 on left column at page 6, are preferably applied.
  • the fluorescent substance used in the present invention preferably comprises substantially Gd 2 O 2 S:Tb.
  • the term "substantially” described here means that main component of the fluorescent substance is Gd 2 O 2 S:Tb, and several % of any other additives to improve the property of the screen, and silica and the like to decorate the surface can preferably be included. And also, in place of Gd, Y, La, or Lu can be possibly mixed inside the ratio of several ten %.
  • fluorescent substance having a heavy density is preferred to absorb X-ray effectively.
  • fluorescent substance that shows a desirable X-ray absorption ability in beam source used for mammography YTaO 4 and the one adding various kinds of activator as the emission center thereto, CaWO 4 , BaFBr:Eu, and the like can be mentioned besides Gd 2 O 2 S:Tb.
  • the image forming method using photothermographic material is perfomed in combination with a fluorescent substance having a main emission peak at 400 nm or lower. And more preferably, the image forming method is performed in combination with a fluorescent substance having a main emission peak at 380 nm or lower. Either single-sided photosensitive material or double-sided photosensitive material can be applied for the assembly.
  • the screen having a main emission peak at 400 nm or lower the screens described in JP-A No. 6-11804 and WO No. 93/01521 and the like are used, but the present invention is not limited to these.
  • crossover cut for double-sided photosensitive material
  • anti-halation for single-sided photosensitive material
  • the technique described in JP-A No. 8-76307 can be applied.
  • ultraviolet absorbing dyes the dye described in JP-A No. 2001-144030 is particularly preferred.
  • the photothermographic material according to the invention can have a non-photosensitive layer in addition to the image forming layer.
  • the non-photosensitive layers can be classified depending on the layer arrangement into (a) a surface protective layer provided on the image forming layer (on the side farther from the support), (b) an intermediate layer provided among plural image forming layers or between the image forming layer and the protective layer, (c) an undercoat layer provided between the image forming layer and the support, and (d) a back layer provided to the side opposite to the image forming layer.
  • a layer that functions as an optical filter may be provided as (a) or (b) above.
  • An antihalation layer may be provided as (c) or (d) to the photothermographic material.
  • thermal development process is usually performed by elevating the temperature of the photothermographic material exposed imagewise.
  • the temperature for development is preferably 90°C to 180°C, more preferably 95°C to 140°C, and further preferably 100°C to 130°C.
  • Time period for development is generally 1 second to 60 seconds, preferably 3 seconds to 30 seconds, and more preferably 5 seconds to 15 seconds.
  • a drum type heater or a plate type heater may be used as for the process for thermal development.
  • a plate type heater process is preferred.
  • a preferable process for thermal development by a plate type heater is a process described in JP-A No. 11-133572, which discloses a thermal developing device in which a visible image is obtained by bringing a photothermographic material with a formed latent image into contact with a heating means at a thermal developing portion, wherein the heating means comprises a plate heater, and a plurality of pressing rollers are oppositely provided along one surface of the plate heater, the thermal developing device is characterized in that thermal development is performed by passing the photothermographic material between the pressing rollers and the plate heater.
  • the plate heater is divided into 2 to 6 portions, with the leading end having a lower temperature by 1°C to 10°C.
  • 4 sets of plate heaters which can be independently subjected to the temperature control, are used, and are controlled so that they respectively become 112°C, 119°C, 121°C, and 120°C.
  • the heater is more stably controlled, and a top part of one sheet of the photothermographic material is exposed and thermal development of the exposed portion is started before exposure of the end part of the sheet has completed,
  • Preferred imagers capable of rapid processing for use in the invention are described in, for example, JP-A Nos. 2002-289804 and 2002-287668.
  • thermal development within 14 seconds is possible with a plate type heater having three heating plates which are controlled, for example, at 107°C, 121°C, and 121°C, respectively.
  • the output time period for the first sheet can be reduced to about 60 seconds.
  • the photothermographic material and the image forming method of the invention are employed for forming black and white images by silver imaging.
  • the photothermographic material and the image forming method of the invention can be employed for medical imaging.
  • the product was pelletized, dried at 130°C for 4 hours, melted at 300°C. Thereafter, the mixture was extruded from a T-die and rapidly cooled to form a non-tentered film.
  • the film was stretched along the longitudinal direction by 3.3 times using rollers of different peripheral speeds, and then stretched along the transverse direction by 4.5 times using a tenter machine.
  • the temperatures used for these operations were 110°C and 130°C, respectively.
  • the film was subjected to thermal fixation at 240°C for 20 seconds, and relaxed by 4% along the transverse direction at the same temperature. Thereafter, the chucking part was slit off, and both edges of the film were knurled. Then the film was rolled up at the tension of 4 kg/cm 2 to obtain a roll having the thickness of 175 ⁇ m.
  • Both surfaces of the support were treated at room temperature at 20 m/minute using Solid State Corona Discharge Treatment Machine Model 6KVA manufactured by Piller GmbH. It was proven that treatment of 0.375 KV ⁇ A ⁇ minute ⁇ m -2 was executed, judging from the readings of current and voltage on that occasion. The frequency upon this treatment was 9.6 kHz, and the gap clearance between the electrode and dielectric roll was 1.6 mm.
  • a solution was prepared by adding 4.3 mL of a 1% by weight potassium iodide solution, and then 3.5 mL of 0.5 mol/L sulfuric acid, 36.5 g of phthalated gelatin, and 160 mL of a 5% by weight methanol solution of 2,2'-(ethylene dithio)diethanol to 1421 mL of distilled water.
  • the solution was kept at 75°C while stirring in a stainless steel reaction vessel, and thereto were added total amount of: solution A prepared through diluting 22.22 g of silver nitrate by adding distilled water to give the volume of 218 mL; and solution B prepared through diluting 36.6 g of potassium iodide with distilled water to give the volume of 366 mL.
  • a method of controlled double jet was executed through adding total amount of the solution A at a constant flow rate over 16 minutes, accompanied by adding the solution B while maintaining the pAg at 10.2.
  • Potassium hexachloroiridate (III) was added in its entirety to give 1 ⁇ 10 -4 mol per 1 mol of silver, at 10 minutes post initiation of the addition of the solution C and the solution D.
  • potassium hexacyanoferrate (II) in an aqueous solution was added in its entirety to give 3 ⁇ 10 -4 mol per 1 mol of silver.
  • 32.7 g of phthalated gelatin was added.
  • the mixture was adjusted to the pH of 3.8 with 0.5 mol/L sulfuric acid. After stopping stirring, the mixture was subjected to precipitation/ desalting/ water washing steps.
  • the mixture was adjusted to the pH of 5.9 with 1 mol/L sodium hydroxide to produce a silver halide dispersion having the pAg of 11.0.
  • the silver halide emulsion A was a pure silver iodide emulsion, and the obtained silver halide grains had a mean projected area equivalent diameter of 0.93 ⁇ m, a variation coefficient of a projected area equivalent diameter distribution of 17.7%, a mean thickness of 0.057 ⁇ m and a mean aspect ratio of 16.3. Tabular grains having an aspect ratio of 2 or more occupied 80% or more of the total projected area.
  • the mean equivalent spherical diameter of the grains was 0.42 ⁇ m. 90% or more of the silver iodide existed in ⁇ phase from the result of powder X-ray diffraction analysis.
  • the mixture was adjusted to the pH of 3.8 with 0.5 mol/L sulfuric acid. After stopping stirring, the mixture was subjected to precipitation/ desalting/ water washing steps. The mixture was adjusted to the pH of 5.9 with 1 mol/L sodium hydroxide to produce a silver halide dispersion having the pAg of 11.0.
  • the above-mentioned silver halide dispersion was kept at 38°C with stirring, and thereto was added 5 mL of a 0.34% by weight methanol solution of 1,2-benzisothiazoline-3-one, and after 40 minutes the temperature was elevated to 60°C.
  • sodium benzene thiosulfonate in a methanol solution was added at 7.6 ⁇ 10 -5 mol per 1 mol of silver.
  • tellurium sensitizer C in a methanol solution was added at 2.0 ⁇ 10 -5 mol per 1 mol of silver and subjected to ripening for 91 minutes.
  • Preparation of silver halide emulsion C was conducted in a similar manner to the process in the preparation of the silver halide emulsion A except that adequately changing the addition amount of a 5 % by weight methanol solution of 2,2'-(ethylene dithio)diethanol, the temperature at grain formation step, and the time for adding the solution A.
  • the silver halide emulsion C was a pure silver iodide emulsion.
  • the obtained silver halide grains had a mean projected area equivalent diameter of 1.369 ⁇ m, a variation coefficient of a projected area equivalent diameter distribution of 19.7%, a mean thickness of 0.130 ⁇ m and a mean aspect ratio of 11.1.
  • Tabular grains having an aspect ratio of 2 or more occupied 80% or more of the total projected area.
  • the mean equivalent spherical diameter of the grains was 0.71 ⁇ m. 90% or more of the silver iodide existed in ⁇ phase from the result of powder X-ray diffraction analysis.
  • Preparation of silver halide emulsion D was conducted in a similar manner to the process in the preparation of silver halide emulsion B, except that using silver halide emulsion C. Thereby, silver halide emulsion D containing 5 mol% of epitaxial silver bromide was prepared.
  • benzothiazolium iodide 7 ⁇ 10 -3 mol per 1 mol of silver with a 1% by weight aqueous solution.
  • the compounds Nos. 1, 2, and 3 were added respectively in an amount of 2 ⁇ 10 -3 mol per 1 mol of silver in silver halide.
  • the compound Nos. 1 and 2 were added respectively in an amount of 8 ⁇ 10 -3 mol per 1 mol of silver halide.
  • Behenic acid manufactured by Henkel Co. (trade name: Edenor C22-85R) in an amount of 100 kg was admixed with 1200 kg of isopropyl alcohol, and dissolved at 50°C.
  • the mixture was filtrated through a 10 ⁇ m filter, and cooled to 30°C to allow recrystallization. Cooling speed for the recrystallization was controlled to be 3 °C/hour.
  • the resulting crystal was subjected to centrifugal filtration, and washing was performed with 100 kg of isopropyl alcohol. Thereafter, the crystal was dried.
  • the resulting crystal was esterified, and subjected to GC-FID analysis to give the results of the content of behenic acid being 96 mol%, lignoceric acid 2 mol%, and arachidic acid 2 mol%. In addition, erucic acid was included at 0.001 mol%.
  • a reaction vessel charged with 635 L of distilled water and 30 L of t-butyl alcohol was kept at 30°C, and thereto were added the total amount of the solution of sodium behenate and the total amount of the aqueous silver nitrate solution with sufficient stirring at a constant flow rate over 93 minutes and 15 seconds, and 90 minutes, respectively.
  • the added material was restricted to the aqueous silver nitrate solution alone.
  • the addition of the solution of sodium behenate was thereafter started, and during 14 minutes and 15 seconds following the completion of adding the aqueous silver nitrate solution, the added material was restricted to the solution of sodium behenate alone.
  • the temperature inside of the reaction vessel was then set to be 30°C, and the temperature outside was controlled so that the liquid temperature could be kept constant.
  • the temperature of a pipeline for the addition system of the solution of sodium behenate was kept constant by circulation of warm water outside of a double wall pipe, so that the temperature of the liquid at an outlet in the leading edge of the nozzle for addition was adjusted to be 75°C.
  • the temperature of a pipeline for the addition system of the aqueous silver nitrate solution was kept constant by circulation of cool water outside of a double wall pipe.
  • Position at which the solution of sodium behenate was added and the position, at which the aqueous silver nitrate solution was added, was arranged symmetrically with a shaft for stirring located at a center. Moreover, both of the positions were adjusted to avoid contact with the reaction liquid.
  • the mixture was left to stand at the temperature as it was for 20 minutes. The temperature of the mixture was then elevated to 35°C over 30 minutes followed by ripening for 210 minutes. Immediately after completing the ripening, solid matters were filtered out with centrifugal filtration. The solid matters were washed with water until the electric conductivity of the filtrated water became 30 ⁇ S/cm. A silver salt of fatty acid was thus obtained. The resulting solid matters were stored as a wet cake without drying.
  • a stock liquid after the preliminary dispersion was treated three times using a dispersing machine (trade name: Microfluidizer M-610, manufactured by Microfluidex International Corporation, using Z type Interaction Chamber) with the pressure controlled to be 1150 kg/cm 2 to give a dispersion of the silver behenate.
  • a dispersing machine trade name: Microfluidizer M-610, manufactured by Microfluidex International Corporation, using Z type Interaction Chamber
  • the pressure controlled to be 1150 kg/cm 2 to give a dispersion of the silver behenate.
  • coiled heat exchangers were equipped in front of and behind the interaction chamber respectively, and accordingly, the temperature for the dispersion was set to be 18°C by regulating the temperature of the cooling medium.
  • reducing agent-1 (2,2'-methylenebis-(4-ethyl-6-tertbutylphenol)
  • 16 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol manufactured by Kuraray Co., Ltd., Poval MP-203
  • a slurry was fed with a diaphragm pump, and was subjected to dispersion with a horizontal sand mill (UVM-2: manufactured by AIMEX Co., Ltd.) packed with zirconia beads having a mean particle diameter of 0.5 mm for 3 hours.
  • UVM-2 manufactured by AIMEX Co., Ltd.
  • a benzoisothiazolinone sodium salt and water were added thereto, thereby adjusting the concentration of the reducing agent to be 25% by weight.
  • This dispersion was subjected to heat treatment at 60°C for 5 hours to obtain reducing agent-1 dispersion.
  • Particles of the reducing agent included in the resulting reducing agent dispersion had a median diameter of 0.40 ⁇ m, and a maximum particle diameter of 1.4 ⁇ m or less.
  • the resultant reducing agent dispersion was subjected to filtration with a polypropylene filter having a pore size of 3.0 ⁇ m to remove foreign substances such as dust, and stored.
  • reducing agent-2 (6,6'-di-t-butyl-4,4'-dimethyl-2,2'-butylidenediphenol)
  • a 10% by weight aqueous solution of modified polyvinyl alcohol manufactured by Kuraray Co., Ltd., Poval MP-203
  • UVM-2 manufactured by AIMEX Co., Ltd.
  • zirconia beads having a mean particle diameter of 0.5 mm for 3 hours and 30 minutes.
  • 0.2 g of a benzoisothiazolinone sodium salt and water were added thereto, thereby adjusting the concentration of the reducing agent to be 25% by weight.
  • This dispersion was warmed at 40°C for one hour, followed by a subsequent heat treatment at 80°C for one hour to obtain reducing agent-2 dispersion.
  • Particles of the reducing agent included in the resulting reducing agent-2 dispersion had a median diameter of 0.50 ⁇ m, and a maximum particle diameter of 1.6 ⁇ m or less.
  • the resultant reducing agent-2 dispersion was subjected to filtration with a polypropylene filter having a pore size of 3.0 ⁇ m to remove foreign substances such as dust, and stored.
  • This dispersion was warmed at 40°C for one hour, followed by a subsequent heat treatment at 80°C for one hour to obtain hydrogen bonding compound-1 dispersion.
  • Particles of the hydrogen bonding compound included in the resulting hydrogen bonding compound dispersion had a median diameter of 0.45 ⁇ m, and a maximum particle diameter of 1.3 ⁇ m or less.
  • the resultant hydrogen bonding compound dispersion was subjected to filtration with a polypropylene filter having a pore size of 3.0 ⁇ m to remove foreign substances such as dust, and stored.
  • Particles of the development accelerator included in the resulting development accelerator dispersion had a median diameter of 0.48 ⁇ m, and a maximum particle diameter of 1.4 ⁇ m or less.
  • the resultant development accelerator dispersion was subjected to filtration with a polypropylene filter having a pore size of 3.0 ⁇ m to remove foreign substances such as dust, and stored.
  • dispersion was executed similar to the development accelerator-1, and thus dispersions of 20% by weight and 15% by weight were respectively obtained.
  • organic polyhalogen compound-1 tribromomethane sulfonylbenzene
  • 10 kg of a 20% by weight aqueous solution of modified polyvinyl alcohol manufactured by Kuraray Co., Ltd., Poval MP-203
  • 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate and 14 kg of water were thoroughly admixed to give a slurry.
  • This slurry was fed with a diaphragm pump, and was subjected to dispersion with a horizontal sand mill (UVM-2: manufactured by AIMEX Co., Ltd.) packed with zirconia beads having a mean particle diameter of 0.5 mm for 5 hours.
  • UVM-2 manufactured by AIMEX Co., Ltd.
  • zirconia beads having a mean particle diameter of 0.5 mm for 5 hours.
  • 0.2 g of a benzisothiazolinone sodium salt and water were added thereto, thereby
  • Particles of the organic polyhalogen compound included in the resulting organic polyhalogen compound dispersion had a median diameter of 0.41 ⁇ m, and a maximum particle diameter of 2.0 ⁇ m or less.
  • the resultant organic polyhalogen compound dispersion was subjected to filtration with a polypropylene filter having a pore size of 10.0 ⁇ m to remove foreign substances such as dust, and stored.
  • organic polyhalogen compound-2 N-butyl-3-tribromomethane sulfonylbenzamide
  • 20 kg of a 10% by weight aqueous solution of modified polyvinyl alcohol manufactured by Kuraray Co., Ltd., Poval MP-203
  • 0.4 kg of a 20% by weight aqueous solution of sodium triisopropylnaphthalenesulfonate were thoroughly admixed to give a slurry.
  • This slurry was fed with a diaphragm pump, and was subjected to dispersion with a horizontal sand mill (UVM-2: manufactured by AIMEX Co., Ltd.) packed with zirconia beads having a mean particle diameter of 0.5 mm for 5 hours. Thereafter, 0.2 g of a benzisothiazolinone sodium salt and water were added thereto, thereby adjusting the concentration of the organic polyhalogen compound to be 30% by weight.
  • UVM-2 manufactured by AIMEX Co., Ltd.
  • This fluid dispersion was heated at 40°C for 5 hours to obtain organic polyhalogen compound-2 dispersion.
  • Particles of the organic polyhalogen compound included in the resulting organic polyhalogen compound dispersion had a median diameter of 0.40 ⁇ m, and a maximum particle diameter of 1.3 ⁇ m or less.
  • the resultant organic polyhalogen compound dispersion was subjected to filtration with a polypropylene filter having a pore size of 3.0 ⁇ m to remove foreign substances such as dust, and stored.
  • Mercapto compound-2 (1-(3-methylureidophenyl)-5-mercaptotetrazole) in an amount of 20 g was dissolved in 980 g of water to give a 2.0% by weight aqueous solution.
  • C.I. Pigment Blue 60 in an amount of 64 g and 6.4 g of DEMOL N manufactured by Kao Corporation were added to 250 g of water and thoroughly mixed to give a slurry.
  • Zirconia beads having the mean particle diameter of 0.5 mm were provided in an amount of 800 g, and charged in a vessel with the slurry.
  • Dispersion was performed with a dispersing machine (1/4G sand grinder mill: manufactured by AIMEX Co., Ltd.) for 25 hours. Thereto was added water to adjust so that the concentration of the pigment became 5% by weight to obtain a pigment-1 dispersion.
  • Particles of the pigment included in the resulting pigment dispersion had a mean particle diameter of 0.21 ⁇ m.
  • SBR Latex (RP-1) was prepared as follows.
  • Degassing was conducted with a vacuum pump, followed by repeating nitrogen gas replacement several times. Thereto was injected 108.75 g of 1,3-butadiene, and the inner temperature is elevated to 60°C. Thereto was added a solution of 1.875 g of ammonium persulfate dissolved in 50 mL of water, and the mixture was stirred for 5 hours as it stands.
  • the temperature was further elevated to 90°C, followed by stirring for 3 hours.
  • filtration with a polypropylene filter having the pore size of 1.0 ⁇ m was conducted to remove foreign substances such as dust followed by storage. Accordingly, SBR latex RP-1 was obtained in an amount of 774.7 g.
  • concentration of chloride ion was revealed to be 3 ppm.
  • concentration of the chelating agent by high performance liquid chromatography it was revealed to be 145 ppm.
  • the aforementioned latex had a mean particle diameter of 90 nm, Tg of 17°C, solid matter concentration of 44% by weight, the equilibrium moisture content at 25°C and 60%RH of 0.6% by weight, ionic conductance of 4.80 mS/cm (measurement of the ionic conductance performed using a conductivity meter CM-30S manufactured by Toa Electronics Ltd. for the latex stock solution (44% by weight) at 25°C).
  • the coating solution for the image forming layer prepared by adding the mixed emulsion for coating solution thereto followed by thorough mixing just prior to the coating was fed directly to a coating die, and was coated.
  • Viscosity of the coating solution was 58 [mPa ⁇ s] which was measured with a B type viscometer at 40°C (No. 1 rotor, 60 rpm).
  • Viscosity of the coating solution was 20 [mPa ⁇ s] which was measured with a B type viscometer at 40°C (No. 1 rotor, 60 rpm).
  • Viscosity of the coating solution was 19 [mPa ⁇ s] which was measured with a B type viscometer at 40°C (No. 1 rotor, 60 rpm).
  • Simultaneous overlaying coating by a slide bead coating method was subjected, on both sides of the support, in order of the image forming layer, intermediate layer, first layer of the surface protective layers and second layer of the surface protective layers, and thus samples of the photothermographic material were produced.
  • the temperature of the coating solution was adjusted to 31°C for the image forming layer and intermediate layer, to 36°C for the first layer of the surface protective layers, and to 37°C for the second layer of the surface protective layers.
  • the amount of coated silver in the image forming layer was 0.821 g/m 2 per one side, with respect to the sum of the amounts of silver salt of fatty acid and silver halide. This was coated on both sides of the support.
  • each compound (g/m 2 ) for the image forming layer per one side is as follows.
  • the thickness of the image forming layer was 10 ⁇ m.
  • the coating amount of silver salt of fatty acid was 0.00625 mol/m 2 .
  • Silver salt of fatty acid A Organic polyhalogen compound-1 0.028 Organic polyhalogen compound-2 0.094
  • Silver iodide complex-forming agent 0.46 Latex binder (see Table 1) 5.20 Reducing agent-1 0.33 Reducing agent-2 0.13 Hydrogen bonding compound-1 0.15 Development accelerator-1 0.005 Development accelerator-2 0.035
  • Silver halide (on the basis of Ag content) 0.146
  • the support was decharged by ionic wind. Coating was performed at the speed of 160 m/min. Conditions for coating and drying were adjusted within the range described below, and conditions were set to obtain the most stable surface state.
  • the clearance between the leading end of the coating die and the support was 0.10 mm to 0.30 mm.
  • the pressure in the vacuum chamber was set to be lower than atmospheric pressure by 196 Pa to 882 Pa.
  • the coating solution was cooled by wind having the dry-bulb temperature of 10°C to 20°C.
  • the coated support was dried with an air of the dry-bulb of 23°C to 45°C and the wet-bulb of 15°C to 21°C in a helical type contactless drying apparatus.
  • moisture conditioning was performed at 25°C in the humidity of 40%RH to 60%RH.
  • the film surface was heated to be 70°C to 90°C, and after heating, the film surface was cooled to 25°C.
  • Compound 1 that can be one-electron-oxidized to provide a one-electron oxidation product which releases one or more electrons
  • Compound 2 that can be one-electron-oxidized to provide a one-electron oxidation product which releases one or more electrons
  • Compound 3 that can be one-electron-oxidized to provide a one-electron oxidation product which releases one or more electrons
  • the resulting sample was cut into a half-cut size, and was wrapped with the following packaging material under an environment of 25°C and 50%RH, and stored for 2 weeks at an ambient temperature.
  • X-ray regular screen HI-SCREEN-B3 (CaWO 4 was used as fluorescent substance, the emission peak wavelength of 425 nm) produced by Fuji Photo Film Co., Ltd. were used, and the assembly for image formation was provided by inserting the sample between them. This assembly was subjected to X-ray exposure for 0.05 seconds, and then X-ray sensitometry was performed.
  • the X-ray apparatus used was DRX-3724HD (trade name) produced by Toshiba Corp., and a tungsten target tube was used.
  • the thermal developing portion of Fuji Medical Dry Laser Imager FM-DP L was modified so that it can heat from both sides, and by another modification the transportation rollers in the thermal developing portion were changed to the heating drum so that the sheet of film could be conveyed.
  • the temperature of four panel heaters were set to 112°C- 118°C- 120°C-120°C, and the temperature of the heating drum was set to 120°C.
  • the total time period for thermal development was set to be 14 seconds.
  • Photothermogaphic material-11 to -16 were prepared as shown in Table 3, using silver halide emulsion F, H, or J instead of silver halide emulsion B, which was used in Sample Nos. 1 and 8 prepared in the Example.
  • Latex P-1b was prepared in a similar manner to the preparation of latex P-1 used for Sample No.1 in Example 1 except that using "SANDET BL” (trade name, available from Sanyo Kasei K.K.) instead of the surfactant "PIONIN A-43-S” (trade name, available from Takemoto Oil & Fat Co., Ltd.) used in the synthesis of latex P-1. Chloride ion concentration of this latex was 553 ppm.
  • Sample No.21 was prepared where latex P-1 used for Sample No.1 was changed for latex P-1b by same weight.
  • the processed photothermographic materials were stored under an environment of 1000 Lux (25°C and 60%RH) for one day and thereafter fog was measured, in addition to the evaluation terms carried out in Example 1.
  • the photothermographic materials containing the polymer latex having a high chloride ion concentration exhibit unfavorable increase in fog after exposure to light.
  • the above-mentioned silver halide dispersion was kept at 38°C with stirring, and thereto was added 5 mL of a 0.34% by weight methanol solution of 1,2-benzisothiazoline-3-one, and after 40 minutes the temperature was elevated to 60°C.
  • sodium benzene thiosulfonate in a methanol solution was added in an amount of 7.6 ⁇ 10 -5 mol per 1 mol of silver.
  • an aqueous solution of sodium thiosulfate pentahydrate was added in an amount of 7.5 ⁇ 10 -5 mol per 1 mol of silver, and then after 10 minutes, an aqueous solution of aurichloric acid and an aqueous solution of potassium thiocyanate were added in an amount of 9 ⁇ 10 -6 mol per 1 mol of silver and 8 ⁇ 10 -3 mol per 1 mol of silver respectively, and subjected to ripening for 90 minutes.
  • a silver halide dispersion containing 10 mol% of epitaxial silver bromide was prepared in a similar manner to the process in the preparation of silver halide emulsion K, except that using silver halide emulsion C of Example 1 instead of using silver halide emulsion A.
  • the above-mentioned silver halide dispersion was kept at 38°C with stirring, and thereto was added 5 mL of a 0.34% by weight methanol solution of 1,2-benzisothiazoline-3-one, and after 20 minutes the temperature was elevated to 50°C. At 20 minutes after elevating the temperature, sodium benzene thiosulfonate in a methanol solution was added in an amount of 7.6 ⁇ 10 -5 mol per 1 mol of silver.
  • a methanol solution of 4-oxo-3-benzyl-oxazolizine-2-thione as a sulfur sensitizer was added thereto in an amount of 4.5 ⁇ 10 -5 mol per 1 mol of silver, and after 10 minutes, an aqueous solution of aurichloric acid and an aqueous solution of potassium thiocyanate were added in an amount of 6 ⁇ 10 -6 mol per 1 mol of silver and 5 ⁇ 10 -3 mol per 1 mol of silver respectively, followed by ripening for 60 minutes.
  • benzothiazolium iodide 1.5 ⁇ 10 -2 mol per 1 mol of silver with a 1% by weight aqueous solution.
  • the compounds Nos. 1, 2, and 3 were added respectively in an amount of 4 ⁇ 10 -3 mol per 1 mol of silver in silver halide.
  • the compound Nos. 1 and 2 were added respectively in an amount of 4 ⁇ 10 -3 mol per 1 mol of silver halide.
  • Photothermographic materials were prepared similar to Example 1, except that using the mixed emulsion 2 for coating solution instead of the mixed emulsion for coating solution used in Example 1.
  • the obtained samples were evaluated similar to Example 1.
  • the photothermographic materials of the present invention attain excellent results in fog, haze, and membrane cracking after processing.

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  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
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Publication number Priority date Publication date Assignee Title
US6300044B1 (en) * 1996-06-13 2001-10-09 Agfa-Gevaert Production method for a photothermographic material and a recording process
US20030232288A1 (en) * 2001-11-05 2003-12-18 Yutaka Oka Photothermographic material and method of thermal development of the same
US20030235795A1 (en) * 2001-08-22 2003-12-25 Fuji Photo Film Co., Ltd. Photothermographic material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6300044B1 (en) * 1996-06-13 2001-10-09 Agfa-Gevaert Production method for a photothermographic material and a recording process
US20030235795A1 (en) * 2001-08-22 2003-12-25 Fuji Photo Film Co., Ltd. Photothermographic material
US20030232288A1 (en) * 2001-11-05 2003-12-18 Yutaka Oka Photothermographic material and method of thermal development of the same

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