JP2007212515A - Heat developable photographic sensitive material and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat developable photosensitive material having low fog, excellent in long-term storage stability and excellent also in silver tone, and an image forming method using the photosensitive material. <P>SOLUTION: The heat developable photosensitive material has an image forming layer containing organic silver, a silver halide, a binder and a reducing agent on a support, wherein the heat developable photosensitive material contains a methylene bisphenol compound having at least one carboxyl group within a molecule in an amount of 0.01-20 mol% based on the amount of the reducing agent. The methylene bisphenol compound having at least one carboxyl group within a molecule is preferably represented by formula (1) or (2) and the reducing agent is preferably represented by formula (3). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silver halide photographic light-sensitive material, and more particularly to a heat-developable photographic light-sensitive material that forms an image by heating and an image forming method using the same.

  In recent years, in the fields of printing plate making and medical treatment, waste liquids resulting from wet processing of image forming materials have become a problem in terms of workability, and further reduction of processing waste liquids is strongly desired from the viewpoint of environmental conservation and space saving. It is rare. As a technique for meeting such demands, a technique for forming a clear black image with high resolution by heat development is known. For example, US Pat. Nos. 3,152,904, 3,457,075 and D. Morgan, “Dry Silver Photographic Materials” (Handbook of Imaging Materials, Marcel Dekker, Inc., page 48, 1991) and the like. Since these photographic materials are usually developed at a temperature of 80 ° C. or higher, they are called photothermographic materials.

  Such a heat-developable photographic light-sensitive material usually contains a reducible non-photosensitive silver salt (for example, organic silver salt), its reducing agent (developer), and a photocatalyst (for example, photosensitive silver halide) in an organic binder matrix. The photosensitive layer contained in a dispersed state on the support is stable at room temperature, but can be reduced after heating by heating to a high temperature between the silver salt (acting as an oxidizing agent) and the reducing agent. Silver is produced by a redox reaction. This redox reaction is promoted by the catalytic action of the latent image generated by exposure. The silver produced by the reaction of the organic silver salt in the exposed area forms a black image, which contrasts with the unexposed area and forms an image.

Conventionally, many of the photothermographic materials of this type have a drawback that fog is increased during storage. In order to improve this drawback, substituted alkene derivatives have been disclosed as fog inhibitors for heat-developable photographic light-sensitive materials (see, for example, Patent Documents 1, 2, and 3). However, these compounds are not yet sufficiently effective in suppressing fogging during storage, and have a problem in the fogging suppressing effect particularly at high temperatures. Furthermore, the photothermographic materials using these compounds are not satisfactory in sensitivity, image storage stability and silver tone, and further improvements have been desired.
US Pat. No. 5,686,228 JP 2002-207273 A JP 2003-140298 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat-developable photographic photosensitive material and an image forming method which are suppressed in fogging and excellent in storage stability with time. An object of the present invention is to provide a photothermographic material (hereinafter also referred to as a photothermographic material) having low fog, little characteristic change due to storage with time, and excellent silver tone, and an image forming method using the same.

The above object of the present invention is achieved by the following configurations.
1.
In a photothermographic material having an image forming layer containing organic silver, silver halide, a binder and a reducing agent on a support, a methylene bisphenol compound having at least one carboxyl group in the molecule is used as the reducing agent. A heat-developable photographic light-sensitive material characterized by containing 0.01 to 20 mol%.
2.
2. The photothermographic material according to item 1, wherein the methylene bisphenol compound having at least one carboxyl group in the molecule is a compound represented by the following general formula (1).

[Wherein, R ₁₁ and R ₁₂ each represents an aliphatic group, and Ar represents an aromatic group or an aromatic heterocyclic group. R ₁₃ and R ₁₄ each represents an aliphatic group. However, at least one of R ₁₁ , R ₁₂ , Ar, R ₁₃ and R ₁₄ has at least one carboxyl group. ]
3.
3. The photothermographic material according to item 2, wherein the compound represented by the general formula (1) is represented by the following general formula (2).

[Wherein, R ₂₁ and R ₂₂ each represents an alkyl group or a cycloalkyl group, and R ₂₃ and R ₂₄ each represents an alkyl group. L represents a divalent linking group, and n represents 0 or 1. ]
4).
4. The photothermographic material according to item 1, 2 or 3, wherein the reducing agent is represented by the following general formula (3).

[Wherein, R ₃₁ and R ₃₂ each represent a secondary or tertiary alkyl group or a cycloalkyl group, and R ₃₃ represents a hydrogen atom or an aliphatic group. R ₃₄ and R ₃₅ each represents an aliphatic group. However, none of R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ contains a carboxyl group. ]
5).
5. An image forming method comprising: developing the photothermographic material according to any one of 1 to 4 above at 80 to 250 ° C. after image exposure with a laser beam.

  According to the present invention, a photothermographic material having high sensitivity, low fog, good storage stability, and excellent silver tone can be provided. In particular, to provide a photothermographic material in which the developed sample does not rise in fog over time, and is a photothermographic photosensor for laser imagers that has high sensitivity and low fog, and good storability of the photosensitive material. Material can be provided.

  Hereinafter, the present invention will be described in detail. First, a methylene bisphenol compound having at least one carboxyl group in the molecule (hereinafter also referred to as a methylene bisphenol compound of the present invention) will be described.

  The methylene bisphenol compound of the present invention is a bisphenol in which the 2-position, 3-position, and 4-position of phenol are linked by a methylene group, and has a substituent at an arbitrary position. And it has at least 1 carboxyl group in either the substituent on the benzene ring of this bisphenol, or the substituent on a methylene group. The methylene bisphenol compound of the present invention is structurally similar to a compound used as a reducing agent (developer) in the field of photothermographic materials, but functions as a reducing agent by having a carboxyl group in the molecule. Instead, the function of fog suppression and development suppression is exhibited. In order to develop the development suppressing function and the fog suppressing function, bisphenols in which the 2-positions or 4-positions of phenol are linked by a methylene group are preferable, and bisphenols in which the 2-positions are bonded by a methylene group are particularly preferable.

  As described above, the methylene bisphenol compound of the present invention functions as a fog inhibitor and a development inhibitor. Therefore, when more than 20 mol% is added to a normal reducing agent, the sensitivity and the maximum concentration are reduced. cause. Moreover, when the addition amount is less than 0.01 mol%, the fog suppression effect is small.

  As a compound which expresses such a function, the compound represented by General formula (1) or General formula (2) is preferable. This will be described in detail below.

In the general formula (1), R ₁₁ and R ₁₂ represent an aliphatic group, and specific examples of the aliphatic group include methyl, ethyl, propyl, i-propyl, normal butyl, t-butyl, pentyl, hexyl. , Decyl, dodecyl, pentadecyl, vinyl, allyl, ethynyl, propargyl, cyclopropyl, cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclopentadienyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, cycloheptyl, cycloheptynyl, cycloheptadienyl , Cyclooctanyl, cyclooctenyl, cyclooctadienyl, cyclooctatrienyl, cyclononanyl, cyclononenyl, cyclononadienyl, cyclononatrienyl cyclodecanyl, cyclodecenyl, cyclodecadienyl, cycl There can be mentioned groups such as decatrienyl. These may further have a substituent.

  Ar represents an aromatic group or an aromatic heterocyclic group. The aromatic group may be a single ring or a condensed ring, and examples thereof include phenyl, naphthyl, anthracenyl, phenanthrenyl, naphthacenyl, triphenylenyl and the like. Specific examples of the aromatic heterocyclic group include groups derived from pyrrole, indole, furan, thiophene, imidazole, pyrazole, carbazole, thiazole, pyridine, oxadiazole, benzoquinoline, thiadiazole, tetrazole, oxazole and the like. Can do. These may further have a substituent.

R ₁₃ and R ₁₄ represent an aliphatic group, and specific examples of the aliphatic group include the groups exemplified for the above R ₁₁ and R ₁₂ . R ₁₃ and R ₁₄ are preferably primary alkyl groups having 1 to 4 carbon atoms.

At least one of R ₁₁ , R ₁₂ , Ar, R ₁₃ and R ₁₄ has at least one carboxyl group, and the total number of carboxyl groups is preferably 1 to 4.

In the general formula (2), R ₂₁ and R ₂₂ represent an alkyl group or a cycloalkyl group, preferably an alkyl group or cycloalkyl group having 12 or less carbon atoms, particularly preferably a secondary or tertiary alkyl group, t Most preferred are -butyl and t-amyl groups.

R ₂₃ and R ₂₄ represent an alkyl group, and a primary alkyl group having 4 or less carbon atoms is preferred.

The divalent linking group represented by L is not particularly limited, and specifically includes —N (R) —, —N (R) —CO—, —N (R) —SO ₂ —, —O—, -OCO -, - S -, - SO -, - SO 2 -, - CO -, - CO 2 -, - CO-N (R) -, an alkylene group, an arylene group, a divalent heterocyclic group, or of Examples thereof include a divalent linking group formed by any combination. R represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group.

  Although the methylene bisphenol compound of this invention is illustrated below, this invention is not limited to these.

  Next, the reducing agent represented by the general formula (3) preferably used in the present invention will be described.

In the general formula (3), R ₃₁ and R ₃₂ represent a secondary or tertiary alkyl group or a cycloalkyl group. Specifically, i-propyl, t-butyl, t-amyl, t-octyl, cyclo Examples include propyl, cyclohexyl, cyclopentyl, methylcyclohexyl and the like. R ₃₁ and R ₃₂ are preferably tertiary alkyl groups.

R ₃₃ represents a hydrogen atom or an aliphatic group, and examples of the aliphatic group include the groups exemplified as the aliphatic group for R ₁₁ and R ₁₂ in the general formula (1). R ₃₃ is preferably a hydrogen atom, an alkyl group, a cycloalkyl group, or a cycloalkenyl group, and particularly preferably a substituent having 8 or less carbon atoms.

Examples of the aliphatic group represented by R ₃₄ and R ₃₅ include the groups exemplified as the aliphatic group in the aforementioned R ₁₁ and R ₁₂ . As R ₃₄ and R ₃₅ , a primary alkyl group having 4 or less carbon atoms is preferable, and an ethyl group is particularly preferable.

  Although the reducing agent represented by General formula (3) is illustrated below, this invention is not limited to these.

  Next, the photothermographic material of the present invention will be described.

  The organic silver salt according to the present invention is a reducible silver source and is an organic acid containing a reducible silver ion source. Examples of the organic acid used include aliphatic carboxylic acids, carbocyclic carboxylic acids, heterocyclic carboxylic acids, heterocyclic compounds, etc., but particularly long chains (10 to 30, preferably 15 to 25 carbon atoms). Of these, aliphatic carboxylic acids and heterocyclic carboxylic acids having a nitrogen-containing heterocyclic ring are preferably used. Also useful are organic silver salt complexes whose ligands have a total stability constant for silver ions of 4.0-10.0. Examples of such organic acid silver salts are described in Research Disclosure (hereinafter abbreviated as RD) 17029 and 29963. Among these, silver salts of fatty acids are preferably used, and silver behenate, silver arachidate and silver stearate are particularly preferably used.

  The organic silver salt compound described above can be obtained by mixing a water-soluble silver compound and a compound that forms a complex with silver, and a normal mixing method, a back mixing method, a simultaneous mixing method, or the like is preferably used. It is also possible to use a controlled double jet method as described in JP-A-9-127643.

  The organic silver salt preferably has an average particle size of 1 μm or less and is monodispersed. The average particle diameter of the organic silver salt refers to the diameter when a sphere equivalent to the volume of the organic silver salt particles is considered when the organic silver salt particles are, for example, spherical, rod-like, or tabular. The average particle size is preferably 0.01 to 0.8 μm, particularly preferably 0.05 to 0.5 μm. Moreover, monodispersion is synonymous with the case of the silver halide mentioned later, Preferably monodispersion degree is 1 to 30%.

  In the present invention, the organic silver salt is more preferably monodisperse particles having an average particle size of 1 μm or less, and an image having a high density can be obtained by setting the content within this range. Further, the organic silver salt preferably has tabular grains of 60% by number or more of the total organic silver. The tabular grains are those having an average grain diameter / thickness ratio, an aspect ratio (abbreviated as AR) represented by the following formula of 3 or more.

AR = average particle diameter (μm) / thickness (μm)
Such organic silver particles are preferably pre-dispersed with a binder, a surfactant or the like, if necessary, and then dispersed and ground with a media disperser or a high-pressure homogenizer. As the disperser that can be used in the preliminary dispersion, for example, a general stirrer such as an anchor type or a propeller type, a high-speed rotating centrifugal radiation type stirrer (dissolver), or a high-speed rotating shear type stirrer (homomixer) can be used. . Examples of the media disperser include a rolling mill such as a ball mill, a planetary ball mill, and a vibrating ball mill, a bead mill that is a medium agitation mill, an attritor, and other basket mills, and a high-pressure homogenizer. For example, various types such as a type that collides with a wall, a plug, etc., a type in which liquids are collided at a high speed after dividing the liquid, and a type in which a thin orifice is passed can be used.

  In the apparatus used for dispersing the organic silver particles, it is preferable to use, for example, ceramics such as zirconia, alumina, silicon nitride, boron nitride, or diamond as the material of the member in contact with the organic silver particles, particularly zirconia. Is preferably used.

  The organic silver particles preferably contain 0.01 to 0.5 mg of Zr per 1 g of silver, and particularly preferably contain 0.01 to 0.3 mg of Zr. When carrying out the above dispersion, optimizing the binder concentration, the preliminary dispersion method, the dispersing machine operating conditions, the number of times of dispersion, etc. is very preferable as a method for obtaining the organic silver salt particles used in the present invention.

  The photosensitive silver halide according to the present invention preferably has a smaller average grain size, and preferably has an average grain size of 0.1 μm or less, more preferably, in order to suppress white turbidity after image formation and to obtain good image quality. 0.01-0.1 micrometer, especially 0.02-0.08 micrometer are preferable. The particle size mentioned here refers to the diameter of a circle having the same area as an individual particle image observed with an electron microscope (equivalent circle diameter). The silver halide is preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 20% or less.

Monodispersity = (standard deviation of particle size) / (average particle size value) × 100
The shape of the photosensitive silver halide grain is not particularly limited, but the ratio occupied by the Miller index [100] plane is preferably high, and this ratio is 50% or more, further 70% or more, and particularly 80% or more. It is preferable. The ratio of the Miller index [100] plane is calculated by using the adsorption dependency between the [111] plane and the [100] plane in the adsorption of the sensitizing dye. Tani, J .; Imaging Sci. 29, 165 (1985).

  Another preferred form of photosensitive silver halide is tabular grain. The tabular grains referred to here are those having an aspect ratio (r / h) of 3 or more when the square root of the projected area is the grain size r μm and the thickness in the vertical direction is h μm. Among them, the aspect ratio is preferably 3 to 50. The particle size of the tabular grains is preferably 0.1 μm or less, and more preferably 0.01 to 0.08 μm. These tabular grains are described in US Pat. Nos. 5,264,337, 5,314,798, 5,320,958 and the like, and the desired tabular grains can be easily obtained.

  The halogen composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide. The emulsion used in the present invention is P.I. By Glafkides: Chimie et Physique Photographic (published by Paul Montel, 1967), G. F. By Duffin: Photographic Emulsion Chemistry (published by The Focal Press, 1966), V.C. L. It can be prepared based on the method described in Zelikman et al: Making and Coating Photographic Emulsion (published by The Focal Press, 1964).

  The photosensitive silver halide preferably contains a metal ion belonging to Groups 6 to 11 of the periodic table. As the metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable. These metal ions can be introduced into the silver halide in the form of metal complexes or metal complex ions. As these metal complexes or metal complex ions, hexacoordinate metal complexes represented by the following general formula are preferable.

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

M is preferably rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) or osmium (Os). Specific examples of transition metal complex ions containing these include [RhCl ₆ ] ³⁻ [RuCl ₆ ] ³⁻ , [ReCl ₆ ] ³⁻ , [RuBr ₆ ] ³⁻ , [OsCl ₆ ] ³⁻ , [IrCl ₆ ] ⁴⁻ , [Ru (NO) Cl ₅ ] ²⁻ , [RuBr ₄ ] (H ₂ O)] ²⁻ , [Ru (NO) (H ₂ O) Cl ₄ ] ⁻ , [RhCl ₅ (H ₂ O)] ²⁻ , [Re (NO) Cl ₅ ] ²⁻ , [Re ( NO) (CN) ₅ ] ²⁻ , [Re (NO) Cl (CN) ₄ ], [Rh (NO) ₂ Cl ₄ ] ⁻ , [Rh (NO) (H ₂ O) Cl ₄ ] ⁻ , [Ru (NO) (CN) _5] ^2-, [Fe (CN) _6] ^3-, [Rh (NS) Cl _5] ^2-, [Os (NO) Cl _5] ^2-, [Cr NO) Cl _5] ^2-, [Re (NO) Cl _5] ^-, _{[Os (NS) Cl 4 (TeCN} ) ] ^2-, [Ru (NS) Cl _5] ^2-, [Re (NS) Cl ₄ (SeCN)] ²⁻ , [Os (NS) Cl (SCN) ₄ ] ²⁻ , [Ir (NO) Cl ₅ ] ²⁻ , [Ir (NS) Cl ₅ ] ^{2− and the} like.

One kind of metal ion, metal complex or metal complex ion described above may be used, or two or more kinds of the same kind of metal and different kinds of metals may be used in combination. The content of these metal ions, metal complexes or metal complex ions is generally 1 × 10 ⁻⁹ to 1 × 10 ⁻² moles per mole of silver halide, preferably 1 × 10 6. ⁻⁸ to 1 × 10 ⁻⁴ mol.

  These metal-providing compounds are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening, chemical sensitization It may be added at any stage before or after, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Add at the stage of formation.

  In the addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains, or JP-A-63-29603, JP-A-2-306236, As described in JP-A-3-167545, JP-A-4-76534, JP-A-6-110146, JP-A-5-273683, and the like, the particles can be included with a distribution. Preferably, distribution can be given inside the particles. These metal compounds can be added by dissolving in water or an appropriate organic solvent (alcohols, ethers, glycols, ketones, esters, amides). For example, an aqueous solution of a metal compound powder or A method in which an aqueous solution in which a metal compound is dissolved together with sodium chloride and potassium chloride is added to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or a silver salt solution and a halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a three-liquid simultaneous mixing method, a method of adding an aqueous solution of a required amount of a metal compound to the reaction vessel during grain formation, or silver halide There is a method of adding and dissolving another silver halide grain previously doped with metal ions or complex ions at the time of preparation. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and sodium chloride and potassium chloride are dissolved together is added to the water-soluble halide solution.

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

  The photosensitive silver halide grains may or may not be desalted after grain formation. However, when desalting is performed, for example, noodle method, flocculation method, etc., water washing by a method known in the art, It can be desalted.

  The silver halide grains are preferably chemically sensitized. As a preferable chemical sensitization method, a sulfur sensitization method, a selenium sensitization method, a tellurium sensitization method and the like well known in the art can be used. Moreover, noble metal sensitization methods and reduction sensitization methods such as gold compounds, platinum, palladium, and iridium compounds can be used.

  As the compound preferably used in the above-described sulfur sensitization method, selenium sensitization method and tellurium sensitization method, known compounds can be used. For example, compounds described in JP-A-7-128768 can be used. Can do. Examples of tellurium sensitizers include diacyl tellurides, bis (oxycarbonyl) tellurides, bis (carbamoyl) tellurides, diacyl tellurides, bis (oxycarbonyl) ditellurides, bis (carbamoyl) ditellurides, P = Compounds having a Te bond, tellurocarboxylates, Te-organyl tellurocarboxylic acid esters, di (poly) tellurides, tellurides, tellurols, telluroacetals, tellurosulfonates, compounds having a P-Te bond, Te-containing heterocycles, tellurocarbonyl compounds, inorganic tellurium compounds, colloidal tellurium, and the like can be used.

  Examples of compounds preferably used for the noble metal sensitization include chloroauric acid, potassium chloroaurate, potassium aurithiocyanate, gold sulfide, gold selenide, US Pat. No. 2,448,060, British Patent 618,061, and the like. And the compounds described.

  As compounds used in the reduction sensitization method, for example, in addition to ascorbic acid and thiourea dioxide, for example, stannous chloride, aminoiminomethanesulfinic acid, hydrazine derivatives, borane compounds, silane compounds, polyamine compounds, etc. may be used. it can. Further, reduction sensitization can be performed by ripening the silver halide emulsion while maintaining the pH at 7 or higher or the pAg at 8.3 or lower. Reduction sensitization can be achieved by introducing a single addition portion of silver ions during grain formation.

  A reducing agent is incorporated in the photothermographic material. Examples of the reducing agent to be used include generally known reducing agents such as phenols, polyphenols having two or more phenols, naphthols, bisnaphthols, and polyhydroxybenzenes having two or more hydroxyl groups. , Polyhydroxynaphthalenes, ascorbic acids, 3-pyrazolidones, pyrazolin-5-ones, pyrazolines, phenylenediamines, hydroxylamines, hydroquinone monoethers, hydrooxamic acids, hydrazides, amide oximes, N -Hydroxyureas and the like, more specifically, for example, U.S. Pat. Nos. 3,615,533, 3,679,426, 3,672,904, 3,751,252, 3,782 No. 949, No. 3,801,321 No. 3,794,48 No. 3,893,863, No. 3,887,376, No. 3,770,448, No. 3,819,382, No. 3,773,512, No. 3,839,048, 3,887,378, 4,009,039, 4,021,240, British Patent 1,486,148, Belgian Patent 786,086, JP 50-36143, 50 -36110, 50-116023, 50-99719, 50-140113, 51-51933, 51-23721, 52-84727, JP-B 51-35851, etc. Can be used, and can be appropriately selected from the above-mentioned known reducing agents. As the selection method, the most efficient method is to confirm the suitability of the reducing agent by actually producing a photothermographic material containing the reducing agent and directly evaluating the photographic performance.

  Among the above reducing agents, preferred reducing agents when using an aliphatic carboxylic acid silver salt as the organic silver salt include polyphenols in which two or more phenols are linked by an alkylene group or sulfur, particularly hydroxy substitution of phenol. Two or more phenols substituted with an alkyl group (methyl, ethyl, propyl, t-butyl, cyclohexyl, etc.) or an acyl group (acetyl, propionyl, etc.) at least one of the positions adjacent to the position are connected by an alkylene group or sulfur Polyphenols such as 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane, 1,1-bis (2-hydroxy-3-tert-butyl-5) -Methylphenyl) methane, 1,1-bis (2-hydroxy-3,5-di-t-butylphenyl) me (2-hydroxy-3-tert-butyl-5-methylphenyl)-(2-hydroxy-5-methylphenyl) methane, 6,6'-benzylidene-bis (2,4-di-tert-butylphenol) 6,6'-benzylidene-bis (2-t-butyl-4-methylphenol), 6,6'-benzylidene-bis (2,4-dimethylphenol), 1,1-bis (2-hydroxy-3) , 5-Dimethylphenyl) -2-methylpropane, 1,1,5,5-tetrakis (2-hydroxy-3,5-dimethylphenyl) -2,4-ethylpentane, 2,2-bis (4-hydroxy) US Pat. Nos. 3,589,903 and 4,021,24 such as 3,5-dimethylphenyl) propane and 2,2-bis (4-hydroxy-3,5-di-t-butylphenyl) propane No. 1, British Patent 1,486,148, JP-A-51-51933, JP-A-50-36110, JP-A-50-11603, JP-A-52-84727, and JP-B-51-35727; Bisnaphthols described in US Pat. No. 3,672,904, such as 2,2′-dihydroxy-1,1′-binaphthyl, 6,6′-dibromo-2,2′-dihydroxy-1,1′- Binaphthyl, 6,6'-dinitro-2,2'-dihydroxy-1,1'-binaphthyl, bis (2-hydroxy-1-naphthyl) methane, 4,4'-dimethoxy-1,1'-dihydroxy-2 2,2'-binaphthyl and the like, and sulfonamidophenols or sulfonamidonaphthols as described in U.S. Pat. No. 3,801,321; for example 4-benzene Examples include sulfonamidophenol, 2-benzenesulfonamidophenol, 2,6-dichloro-4-benzenesulfonamidophenol, 4-benzenesulfonamidonaphthol, and polyphenol compounds described in JP-A Nos. 2003-3302723 and 2004-4767. I can do it. Particularly preferred are polyphenol compounds described in JP-A Nos. 2003-3302723 and 2004-4767.

  The appropriate amount of the reducing agent used in the photothermographic material is not uniform depending on the organic silver salt used, the type of the reducing agent, and other additives, but generally 0.05 to 1 mol per mol of the organic silver salt. A range of 10 moles, preferably 0.1-3 moles, is appropriate. Within this range, two or more of the reducing agents described above may be used in combination. In the present invention, it is preferable to add and apply the reducing agent to the photosensitive layer coating solution immediately before coating in order to reduce the photographic performance fluctuation due to the stagnation time of the photosensitive layer coating solution.

  Next, components of the photothermographic material of the present invention excluding the above-described items will be described.

  The photothermographic material of the present invention is obtained by laminating an image forming layer and a protective layer containing the above-described organic silver salt, photosensitive silver halide, and reducing agent on a support in this order. What comprises an intermediate | middle layer between a support body and the said image forming layer as needed is preferable.

  Further, a photothermographic material in which a backing layer is provided on the surface opposite to the image forming layer in order to ensure transportability and prevent blocking with the protective layer can also be suitably used. Each layer may be a single layer, or may be composed of two or more layers having the same or different composition.

  In the present invention, a binder resin is preferably used to form each of the above layers. As such a binder resin, a conventionally used transparent or translucent binder resin can be selected and used as appropriate. Examples of such a binder resin include polyvinyl formal, polyvinyl acetoacetal, and polyvinyl butyral. Polyvinyl acetal resin: Cellulose resin such as ethyl cellulose, hydroxyethyl cellulose, cellulose acetate butyrate; Styrene resin such as polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-acrylic rubber copolymer; polyvinyl chloride, chlorination Examples include vinyl chloride resins such as polypropylene; polyesters, polyurethanes, polycarbonates, polyarylates, epoxy resins, acrylic resins, and the like. These may be used alone or in combination of two or more types. It may be used in combination.

  In addition, the said binder resin can be suitably selected and used for each layer of a protective layer, an intermediate | middle layer, or the backcoat layer provided when needed, unless the objective of this invention is impaired. In addition, you may use an epoxy resin, an acrylic monomer, etc. which can be hardened | cured with an active energy ray as a layer formation binder resin for an intermediate | middle layer and a backcoat layer. In the present invention, the following aqueous binder resins are also preferably used.

  As a preferable resin, a water-soluble polymer or a water-dispersible hydrophobic polymer (latex) can be used. For example, polyvinylidene chloride, vinylidene chloride-acrylic acid copolymer, vinylidene chloride-itaconic acid copolymer, sodium polyacrylate, polyethylene oxide, acrylic acid amide-acrylic acid ester copolymer, styrene-maleic anhydride copolymer Acrylonitrile-butadiene copolymer, vinyl chloride-acetic acid part nyl copolymer, styrene-butadiene-acrylic acid copolymer, and the like. These constitute an aqueous coating solution, but form a uniform resin film at the stage of drying after coating and forming a coating film. When these are used, an organic silver salt, silver halide, reducing agent, etc. as an aqueous dispersion, mixed with these latexes to form a uniform dispersion, and then applied to form a heat-developable image forming layer Can be formed. By drying, the latex coalesces and forms a uniform film. Furthermore, a polymer having a glass transition point (Tg) of -20 to 80 ° C is preferable, and a polymer having a glass transition point (Tg) of -5 to 60 ° C is particularly preferable. This is because when Tg is high, the temperature at which heat development is performed becomes high, and when Tg is low, fogging is likely to occur, leading to a decrease in sensitivity and softening. The water-dispersed polymer is preferably dispersed as fine particles having an average particle diameter in the range of 1 nm to several μm. The water-dispersed hydrophobic polymer is called a latex and is preferably a latex that improves water resistance among widely used binders for aqueous coating.

  The amount of latex used for the purpose of obtaining water resistance as a binder is determined in consideration of applicability, but is preferably as large as possible from the viewpoint of moisture resistance. The ratio of latex to the total binder mass is preferably 50 to 100%, particularly preferably 80 to 100%.

As these binder resins, the amount of solids is 0.25 to 10 times the amount of silver, for example, when the amount of silver is 2.0 g / m ² , the amount of polymer is 0.5 to 20 g. / M ² is preferable. Further, more preferably 0.5 to 7 times the grain-weight, for example if the amount with silver 2.0 g / m ^2, a 1.0~14g / m ^2. If the amount of binder resin is less than 0.25 times the amount of silver attached, the silver tone will deteriorate significantly and may not be usable, and if it is more than 10 times the amount of silver attached, it may become soft and unusable. .

  Further, the image forming layer according to the present invention includes, in addition to the above-described essential components and binder resin, an antifoggant, a toning agent, a sensitizing dye, and a substance exhibiting supersensitization (supersensitization). Various additives may also be added.

Antifoggants include, for example, compounds such as those disclosed in US Pat. Nos. 3,874,946 and 4,756,999, —C (X ₁ ) (X ₂ ) (X ₃ ) (where X ₁ and X ₂ each represent a halogen atom, and X ₃ represents hydrogen or a halogen atom), heterocyclic compounds having one or more substituents represented by JP-A-9-288328, JP-A-9-90550, US Patent The compounds disclosed in US Pat. No. 5,028,523 and European Patents 600,587, 605,981, 631,176, etc. can be selected and used as appropriate.

  Examples of toning agents added for the purpose of improving the silver tone after development include imides (phthalimide and the like); cyclic imides, pyrazolin-5-ones, and quinazolinones (succinimide, 3-phenyl-2-pyrazolin- 5-one, 1-phenylurazole, quinazoline, 2,4-thiazolidinedione, etc.); naphthalimides (N-hydroxy-1,8-naphthalimide, etc.); cobalt complexes (such as hexamine trifluoroacetate of cobalt), mercaptans (3-mercapto-1,2,4-triazole, etc.); N- (aminomethyl) aryl dicarboximides (N- (dimethylaminomethyl) phthalimide, etc.); blocked pyrazoles, isothiuronium derivatives and certain species A combination of photobleaching agents (N, N′-hexamethylene (1 Carbamoyl-3,5-dimethylpyrazole), 1,8- (3,6-dioxaoctane) bis (isothiuronium trifluoroacetate), and 2- (tribromomethylsulfonyl) benzothiazole); merocyanine dye (3-ethyl-5-((3-ethyl-2-benzothiazolinylidene (benzothiazolinylidene))-1-methylethylidene) -2-thio-2,4-oxazolidinedione); phthalazinone, phthalazinone Derivatives or metal salts of these derivatives (4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, 2,3-dihydro-1,4-phthalazinedione, etc.) A combination of phthalazinone and a sulfinic acid derivative (6-chlorophthalazinone + sodium benzenesulfinate) Or phthalazine + phthalic acid combination; phthalazine (including adducts of phthalazine) and maleic anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or a combination with at least one compound selected from o-phenylene acid derivatives and anhydrides thereof (phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride); quinazolinediones, benzoxazines, naltoxazines Derivatives; benzoxazine-2,4-diones (1,3-benzoxazine-2,4-dione etc.); pyrimidines and asymmetric-triazines (2,4-dihydroxypyrimidine etc.), and tetraazapentalene Derivatives (3,6-dimercapto-1,4-diphenyl-1H, 4H-2 , 3a, 5,6a-tetrazapentalene, etc.), and preferred toning agents are phthalazone and phthalazine. In addition, if it is a range which does not inhibit the objective of this invention, you may add a toning agent to the protective layer mentioned later.

  The supersensitizers are described in RD17643, Japanese Patent Publication Nos. 9-25500, 43-4933, JP-A-59-19032, 59-192242, JP-A-5-341432, and the like. A compound can be selected and used in a timely manner. In the present invention, a heteroaromatic mercapto compound represented by the following general formula (M), which is substantially represented by the general formula (Ma) that produces the mercapto compound, can be used. Disulfide compounds can be used.

Formula (M) Ar-SM
Formula (Ma) Ar-SS-Ar
In the general formula (M), M represents a hydrogen atom or an alkali metal atom, and Ar represents a heteroaromatic ring or condensed heteroaromatic ring having one or more nitrogen, sulfur, oxygen, selenium or tellurium atoms. The heteroaromatic ring is preferably a benzimidazole, naphthimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotelrazole, imidazole, oxazole, pyrazole, triazole, triazine, pyrazine, pyridazine, pyrazine, pyridine , Purine, quinoline or quinazoline. In the general formula (Ma), Ar has the same meaning as in the general formula (M).

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

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

  The image forming layer can contain a macrocyclic compound containing a hetero atom. A 9-membered or larger macrocyclic compound containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom as a heteroatom is preferred, a 12-24 membered ring is more preferred, and a 15-21 membered ring is still more preferred. is there. A typical compound is crown ether, which was synthesized by Pederson in 1967 and has been synthesized many times since its unique report. These compounds are C.I. J. et al. Pederson: Journal of American chemical society vol, 86 (2495), 7017-7036 (1967), G.P. W. Gokel, S.M. H, Korzenowski: Macrocyclic polyethr synthesis, Springer-Vergal (1982).

  In addition to the additives described above, for example, surfactants, antioxidants, stabilizers, plasticizers, ultraviolet absorbers, coating aids and the like may be used for the image forming layer. As these additives and the other additives described above, compounds described in RD17029 (June 1978, pages 9 to 15) are preferably used.

  Photothermographic materials include, for example, JP-A Nos. 63-159842, 60-140335, 63-231437, 63-259651, 63-304242, 63-15245, U.S. Pat. 639,414, 4,740,455, 4,741,966, 4,751,175, and 4,835,096 can be used. Specific examples of useful sensitizing dyes are described in, for example, documents described or cited in Section RD17643IV-A (December 1978, page 23) and Section 18431X (August 1979, page 437).

  In the present invention, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, for A) an argon laser light source, see JP-A-60-162247, JP-A-2-48653, US Pat. No. 2,161,331, West German Patent 936,071, JP-A-5-11389, etc. For the simple merocyanines described above and B) helium-neon laser light sources, trinuclear cyanine dyes described in JP-A-50-62425, JP-A-54-18726, JP-A-59-102229, etc. JP-A-48-42172, JP-A-51-9609, JP-A-55-39818, JP-A-62-284343, JP-A-Hei. Japanese Patent Application Laid-Open No. 59-191032 and No. 6 for the thiacarbocyanines described in JP-A-2-105135 and D) infrared semiconductor laser light sources. Tricarbocyanines described in Japanese Patent No. 80841, dicarboxylic acids containing 4-quinoline nuclei described in general formulas (IIIa) and (IIIb) of JP-A-59-192242 and JP-A-3-67242 Carbocyanines and the like are advantageously selected.

  These sensitizing dyes may be used singly or in combination. The combination of sensitizing dyes itself has a spectral sensitizing action, particularly with a sensitizing dye often used for the purpose of supersensitization. The silver halide emulsion may contain a dye having no color or a substance that does not substantially absorb visible light and exhibits supersensitization.

  The image forming layer may be a single layer or a plurality of layers having the same or different composition. The film thickness of the image forming layer is usually 10 to 30 μm.

  Next, the support and protective layer, which are essential as the layer structure of the photothermographic material, will be described in detail.

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

  As the dye used, known compounds that absorb light in various wavelength regions can be used depending on the color sensitivity of the photosensitive material. For example, when the photothermographic material of the present invention is used as an image recording material by infrared light, a squarylium dye having a thiopyrylium nucleus as disclosed in JP-A-2001-83655 (in this specification, thiopyrylium squarylium). And a squarylium dye having a pyrylium nucleus (referred to herein as a pyrylium squarylium dye), or a thiopyrylium croconium dye similar to a squarylium dye, or a pyrylium croconium dye. .

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

  As the dye, compounds described in JP-A-8-201959 are also preferable.

  Examples of the support used for the photothermographic material include acrylic acid ester, methacrylic acid ester, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), polycarbonate (PC), polyarylate, polyvinyl chloride, Each of polyethylene (PE), polypropylene (PP), polystyrene (PS), nylon (Ny), aromatic polyamide, polyetheretherketone, polysulfone, polyethersulfone, polyimide, polyetherimide, triacetylcellulose (TAC), etc. Examples thereof include a resin film and a resin film formed by laminating two or more layers of the resin.

  In the image forming method described below, the support used in the present invention is developed with heat after the latent image is formed to form an image. Therefore, a support that has been stretched into a film and heat-set is preferable in terms of dimensional stability. In addition, you may add fillers, such as a titanium oxide, a zinc oxide, barium sulfate, a calcium carbonate, in the range which does not inhibit the effect of this invention. The thickness of the support is about 10 to 500 μm, preferably 25 to 250 μm.

  As the protective layer used in the photothermographic material, the binder resin described in the above image forming layer can be selected and used as necessary. As an additive to be added to the protective layer, it is preferable to contain a filler for the purpose of ensuring scratch resistance and transportability of the image after heat development, and the content when the filler is added is a protective layer forming component. 0.05 to 30% by mass of is preferable.

  Furthermore, in order to improve slipperiness and chargeability, the protective layer may contain a lubricant and an antistatic agent. Examples of such lubricants include fatty acids, fatty acid esters, fatty acid amides, polyoxyethylenes, polyoxypropylenes, (modified) silicone oils, (modified) silicone resins, fluorine resins, fluorocarbons, waxes, and the like. In addition, as an antistatic agent, a cationic surfactant, an anionic surfactant, a nonionic surfactant, a polymer antistatic agent, a metal oxide or a conductive polymer, etc., “11290 chemical products” Examples include compounds described in Chemical Industry Daily, pages 875 to 876, and compounds described in columns 14 to 20 of US Pat. No. 5,244,773. Furthermore, various additives added to the image forming layer may be added to the protective layer as long as the object of the present invention is not hindered. About 20 mass% is preferable, More preferably, it is 0.05-10 mass%.

  The protective layer may be a single layer or a plurality of layers having the same or different composition. In addition, the film thickness of a protective layer is 1.0-5.0 micrometers normally.

  In the present invention, in addition to the above-mentioned image forming layer, support and protective layer, an intermediate layer for improving film attachment between the support and the image forming layer, and a back coat layer for the purpose of transportability and antistatic In the case of installation, the thickness of the intermediate layer is usually 0.05 to 2.0 μm, and the thickness of the backcoat layer is usually 0.1 to 10 μm.

  The coating solution for the image forming layer, the coating solution for the protective layer, and the coating solution for the intermediate layer and the backcoat layer, which are installed as necessary, according to the present invention each have the above-described components dissolved or dispersed in a solvent. Can be prepared.

  Solvents that can be used in the above preparation may be those having a solubility parameter value in the range of 6.0 to 15.0 shown in “Solvent Pocket Book” edited by the Society of Synthetic Organic Chemistry. Examples of the solvent that can be used in the coating solution for forming, include ketones such as acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, and methyl-i-butyl ketone. Examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol. Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and hexylene glycol. Examples of ether alcohols include ethylene glycol monomethyl ether and diethylene glycol monoethyl ether. Examples of ethers include ethyl ether, dioxane, i-propyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate, amyl acetate, and i-propyl acetate. Examples of hydrocarbons include pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene and the like. Examples of chlorides include methyl chloride, methylene chloride, chloroform, dichlorobenzene and the like. However, it is not limited to these as long as the effects of the present invention are not impaired.

These solvents can be used alone or in combination of several kinds. The residual amount of the solvent in the photothermographic material can be adjusted by appropriately setting the temperature conditions of the drying step after coating, and the residual solvent amount is preferably 5 to 1000 mg / m ^{2 in} total. preferably, a 10-300 mg / m ^2.

  When dispersion is necessary when preparing the coating solution, for example, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a cobol mill, a tron mill, a sand mill, a sand grinder, a Sqgvari attritor, a high-speed impeller disperser, a high-speed stone mill A conventionally known disperser such as a high-speed impact mill, a disper, a high-speed mixer, a homogenizer, an ultrasonic disperser, an open kneader, or a continuous kneader can be selected and used in a timely manner.

  In order to apply the coating solution prepared as described above, for example, extrusion type extrusion coater, reverse roll coater, gravure roll coater, air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, bar coater, transfer coater Various known coater stations such as a roll coater, a kiss coater, a cast coater, and a spray coater can be appropriately selected and used. Among these coaters, it is preferable to use a roll coater such as an extrusion type extrusion coater or a reverse roll coater in order to eliminate unevenness in the thickness of the formation layer.

  Further, when the protective layer is applied, there is no particular limitation as long as the image forming layer is not damaged, but the solvent used in the protective layer forming coating solution may dissolve the image forming layer. In the above-described coater station, an extrusion-type extrusion coater, a gravure roll coater, a bar coater, or the like can be used. Of these, when a contact coating method such as a gravure roll coater or bar coater is used, the rotation direction of the gravure roll or bar may be forward or reverse with respect to the transport direction. In some cases, a constant speed difference or a peripheral speed difference may be provided.

  Furthermore, when laminating each constituent layer, coating and drying may be repeated for each layer, but simultaneous multilayer coating may be performed by a wet-on-wet method and dried. In that case, for example, a reverse roll coater, a gravure roll coater, an air doctor coater, a blade coater, an air knife coater, a squeeze coater, an impregnation coater, a bar coater, a transfer roll coater, a kiss coater, a cast coater, a spray coater, and an extrusion type extrusion coater In such a wet-on-wet multi-layer application, the upper layer is applied while the lower layer remains wet, improving the adhesion between the upper and lower layers. To do.

  Furthermore, in the present invention, it is preferable that the temperature at which the coating film is dried is in the range of 65 to 100 ° C. in order to effectively bring out the effects of the present invention after applying at least the image forming layer coating solution. When the drying temperature is lower than 65 ° C., the reaction is insufficient, and thus the sensitivity may vary with time. When the drying temperature is higher than 100 ° C., the photothermographic material itself immediately after production is fogged. (Coloring) may occur, which is not preferable. The drying time cannot be generally specified by the air volume at the time of drying, but it is usually preferable to dry in the range of 2 to 30 minutes.

  In addition, the above-mentioned drying temperature may be dried at a drying temperature in the above-mentioned temperature range immediately after coating, or the vicinity of the surface generated by the marangoni of the coating liquid generated during drying or the drying air of warm air is initially dried. For the purpose of preventing unevenness (coconut skin) caused by this, the initial drying temperature may be lower than 65 ° C., and then dried at a drying temperature in the above-described temperature range.

  As described above, the photothermographic material of the present invention and the preferred production method thereof can achieve the object of the present invention, but further, by optimizing the image recording method, a clear image without interference fringes can be obtained. be able to.

  Next, an image forming method suitable for the photothermographic material of the invention will be described in detail.

  Image forming methods that can be used are roughly divided into three modes depending on the angle between the exposure surface and the laser beam, the wavelength of the laser, and the number of lasers used, and these may be performed alone or in combination of two or more. These modes may be combined, and by using such an image forming method, a clear image without interference fringes can be obtained.

  As a preferred embodiment of the image forming method of the present invention, an image is formed by scanning exposure using a laser beam in which the angle formed by the laser beam and the exposure surface of the photothermographic material is not substantially perpendicular. Can be mentioned. In this way, by shifting the incident angle from the vertical, even if reflected light at the interlayer interface is generated, the optical path difference reaching the image forming layer increases, so that the laser light is scattered or attenuated in the optical path. It is difficult to generate interference fringes. Note that “not substantially vertical” means that the angle that is closest to the vertical during laser scanning is preferably 55 to 88 degrees, more preferably 60 to 86 degrees, and still more preferably 65 to 84 degrees. Say there is.

  Further, a more preferable aspect of the image forming method of the present invention is to form an image by scanning exposure using a vertical multi-laser having a single exposure wavelength. When scanning with such a vertical multi-laser beam having a width in wavelength, the generation of interference fringes is reduced as compared with a scanning laser beam of a vertical single mode. The term “vertical multi” as used herein means that the exposure wavelength is not single, and the exposure wavelength distribution is usually 5 nm or more, preferably 10 nm or more. The upper limit of the exposure wavelength distribution is not particularly limited, but is usually about 60 nm.

Further, in the above-described image forming method, as a laser used for scanning exposure, generally known solid lasers such as ruby laser, YAG laser, and glass laser; He—Ne laser, Ar ion laser, Kr ion laser, CO Gas laser such as ₂ laser, CO laser, He—Cd laser, N ₂ laser, excimer laser; semiconductor laser such as InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb laser; chemical laser A dye laser or the like can be selected and used in a timely manner. However, in the image forming method according to claim 5, a semiconductor laser having a wavelength of 600 to 1200 nm is used due to maintenance and the size of the light source. It is characterized by being preferably used.

  In a laser used in a laser imager or a laser image setter, the beam spot diameter on the exposed surface of the photothermographic material when scanned with the photothermographic material is generally 5 to 75 μm as the minor axis diameter. The shaft diameter is in the range of 5 to 100 μm, and the laser beam scanning speed can be set to an optimum value for each photothermographic material depending on the sensitivity and laser power at the laser oscillation wavelength inherent to the photothermographic material.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “mass%” and “parts” represents “parts by mass”.

Example 1
[Preparation of subtracted photographic support]
<Preparation of PET undercoated photographic support>
Corona discharge of 8 W / m ² · min on both sides of a commercially available biaxially stretched heat-fixed thickness of 175 μm and blue-colored PET film with an optical density of 0.170 (measured with Konica Densitometer PDA-65) After applying the treatment, the following undercoat coating solution a-1 is applied on one side so as to have a dry film thickness of 0.8 μm and dried to form an undercoat layer A-1, and on the opposite side, The undercoating liquid b-1 was applied to a dry film thickness of 0.8 μm and dried to form an undercoat layer B-1.
<< Undercoat coating liquid a-1 >>
Copolymer latex liquid of butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate (30/20/25/25%) (solid content 30%)
270g
C-1 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water << Undercoating liquid b-1 >>
Copolymer latex solution of butyl acrylate / styrene / glycidyl acrylate (40/20/40%) (solid content 30%) 270 g
C-1 0.6g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water.

Subsequently, a corona discharge of 8 W / m ² · min is applied to the upper surfaces of the undercoat layer A-1 and the undercoat layer B-1, and the following undercoat upper layer coating solution a- 2 is coated on the undercoating layer B-1 so that the dry film thickness is 0.1 μm, and the following undercoating upper layer coating solution b-2 is applied so that the dry film thickness is 0.8 μm. The upper upper layer A-2 and the lower upper layer B-2 having an antistatic function were formed.
<< Undercoating upper layer coating liquid a-2 >>
Mass to become gelatin 0.4g / m ² C-1 0.2g
C-2 0.2g
C-3 0.1g
Silica particles (average particle size 3μm) 0.1g
Finish to 1 liter with water << Undercoating upper layer coating liquid b-2 >>
C-4 60g
Latex liquid containing C-5 as a component (solid content 20%) 80 g
Ammonium sulfate 0.5g
C-6 12g
Polyethylene glycol (weight average molecular weight 600) 6g
Finish to 1 liter with water.

<Back side application>
While stirring 830 g of methyl ethyl ketone (MEK), 84.2 g of cellulose acetate butyrate (manufactured by Eastman Chemical: CAB381-20) and 4.5 g of polyester resin (manufactured by Bostic: VitelPE2200B) were added and dissolved. Next, 0.30 g of infrared dye 1 was added to the solution, and 4.5 g of a fluorine-based activator (Asahi Glass Co., Ltd .: Surflon KH40) dissolved in 43.2 g of methanol and a fluorine-based activator (Dainippon Ink, Inc.) 2.3 g) (manufactured by Megafag F120K) was added and stirred well until dissolved. Finally, 75 g of silica (manufactured by WR Grace: Syloid 64X6000) dispersed in MEK at a concentration of 1% with a dissolver type homogenizer was added and stirred to prepare a coating solution for the back surface side.

  The back surface coating solution thus prepared was coated and dried by an extrusion coater so that the dry film thickness was 3.5 μm. It dried for 5 minutes using the drying air with a drying temperature of 100 degreeC, and dew point temperature of 10 degreeC.

<< Preparation of photosensitive silver halide emulsion A >>
(A1)
Phenylcarbamoylated gelatin 88.3g
Compound A (10% aqueous methanol solution) 10 ml
Potassium bromide 0.32g
Finish to 5429 ml with water (B1)
0.67 mol / L silver nitrate aqueous solution 2635 ml
(C1)
Potassium bromide 51.55g
Potassium iodide 1.47g
Finish to 660ml with water (D1)
Potassium bromide 154.9g
4.41 g of potassium iodide
Iridium chloride (1% solution) 0.93ml
Finish to 1982ml with water (E1)
0.4 mol / L potassium bromide aqueous solution The following silver potential control amount (F1)
Potassium hydroxide 0.71g
Finish to 20ml with water (G1)
56% acetic acid aqueous solution 18.0 ml
(H1)
Anhydrous sodium carbonate 1.72 g
Finish to 151 ml with water Compound A: HO (CH ₂ CH ₂ O) _n (CH (CH ₃ ) CH ₂ O) ₁₇ (CH ₂ CH ₂ O) _m H
(M + n = 5-7).

  Using the mixing stirrer shown in Japanese Patent Publication Nos. 58-58288 and 58-58289, the solution (A1) is controlled to 1/4 of the solution (B1) and the total amount of the solution (C1) to 45 ° C. and pAg 8.09. While adding 4 minutes 45 seconds by the simultaneous mixing method, nucleation was performed. After 1 minute, the entire amount of solution (F1) was added. During this time, pAg was adjusted appropriately using (E1). After 6 minutes, 3/4 amount of the solution (B1) and the whole amount of the solution (D1) were added over 14 minutes and 15 seconds by the simultaneous mixing method while controlling the temperature at 45 ° C. and pAg 8.09. After stirring for 5 minutes, the temperature was lowered to 40 ° C., the whole amount of the solution (G1) was added, and the silver halide emulsion was precipitated. The supernatant was removed leaving 2000 ml of the sedimented portion, 10 liters of water was added, and after stirring, the silver halide emulsion was sedimented again. The remaining portion of 1500 ml was left, the supernatant was removed, 10 liters of water was further added, and after stirring, the silver halide emulsion was precipitated. After leaving 1500 ml of the sedimented portion and removing the supernatant, the solution (H1) was added, the temperature was raised to 60 ° C., and the mixture was further stirred for 120 minutes. Finally, the pH was adjusted to 5.8, and water was added so that the amount was 1161 g per mole of silver, whereby photosensitive silver halide emulsion A was obtained.

  This emulsion was monodisperse cubic silver iodobromide grains having an average grain size of 0.058 μm, a grain size variation coefficient of 12%, and a [100] face ratio of 92%.

  Next, 240 ml of sulfur sensitizer S-5 (0.5% methanol solution) was added to the emulsion, and gold sensitizer Au-5 corresponding to 1/20 mol of this sensitizer was added. Chemical sensitization was performed by stirring at 120 ° C. for 120 minutes.

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

  Next, 702.6 ml of 1 mol / L silver nitrate solution was added over 2 minutes and stirred for 10 minutes to obtain an organic silver salt dispersion. Thereafter, the obtained organic silver salt dispersion was transferred to a water-washing container, deionized water was added and stirred, and then allowed to stand to float and separate the organic silver salt dispersion, thereby removing the lower water-soluble salts. Thereafter, washing and draining with deionized water was repeated until the electrical conductivity of the drainage reached 2 μS / cm, and centrifugal dehydration was carried out. Then, the obtained cake-like organic silver salt was converted into an air-flow dryer Flashjet dryer (Seishin). The product was dried until the water content became 0.1% according to the operating conditions of the nitrogen gas atmosphere and the dryer inlet hot air temperature to obtain a dried organic silver salt A of an organic silver salt. In addition, the infrared moisture meter was used for the moisture content measurement of an organic silver salt composition.

<< Preparation of Preliminary Dispersion A >>
Dissolve 14.57 g of polyvinyl butyral powder (Monsanto: Butvar B-79) in 1457 g of MEK and gradually add 500 g of powdered organic silver salt A while stirring with a dissolver DISPERMAT CA-40M manufactured by VMA-GETZMANN. Preliminary dispersion A was prepared by thorough mixing.

<< Preparation of photosensitive emulsion dispersion 1 >>
Media type disperser DISPERMAT filled with 80% of the internal volume of 0.5 mm zirconia beads (Toray Industries, Inc .: Treceram) so that the residence time in the mill is 1.5 minutes using a pump. Photosensitive emulsion dispersion 1 was prepared by supplying to SL-C12EX type (manufactured by VMA-GETZMANN) and dispersing at a mill peripheral speed of 8 m / s.

<< Preparation of stabilizer liquid >>
1.0 g of Stabilizer 1 and 0.31 g of potassium acetate were dissolved in 4.97 g of methanol to prepare a stabilizer solution.

<< Preparation of infrared sensitizing dye liquid A >>
19.2 mg of sensitizing dye 1, 1.488 g of 2-chloro-benzoic acid, 2.7779 g of stabilizer 2 and 365 mg of 5-methyl-2-mercaptobenzimidazole in 31.3 ml of MEK in the dark It melt | dissolved and the infrared sensitizing dye liquid A was prepared.

<< Preparation of Additive Liquid a >>
A reducing agent (described in Table 1), a compound represented by the general formula (1) or (2) (described in Table 1), 1.54 g of 4-methylphthalic acid, and 0.48 g of infrared dye 1 are added to 110 g of MEK. It melt | dissolved and it was set as the addition liquid a.

<< Preparation of additive liquid b >>
9 × 10 ^- 3 mol of polyhalogen compound 1 and phthalazine 3.43g was added liquid b was dissolved in MEK40.9G.

<< Preparation of photosensitive layer coating solution >>
In an inert gas atmosphere (nitrogen 97%), 50 g of the photosensitive emulsion dispersion 1 and 15.11 g of MEK were kept at 21 ° C. with stirring, and chemical sensitizer S-5 (0.5% methanol solution) 1000 μl was added, and after 2 minutes, 390 μl of antifoggant 1 (10% methanol solution) was added and stirred for 1 hour. Further, after adding 494 μl of calcium bromide (10% methanol solution) and stirring for 10 minutes, gold sensitizer Au-5 corresponding to 1/20 mol of the above organic chemical sensitizer was added, and further stirred for 20 minutes. did. Subsequently, 167 ml of a stabilizer solution was added and stirred for 10 minutes, and then 1.32 g of the infrared sensitizing dye solution was added and stirred for 1 hour. Thereafter, the temperature was lowered to 13 ° C. and further stirred for 30 minutes. While maintaining the temperature at 13 ° C., 13.31 g of polyvinyl butyral (above: B-79) was added and stirred for 30 minutes, and then 1.084 g of tetrachlorophthalic acid (9.4% MEK solution) was added and 15 Stir for minutes. While further stirring, 12.43 g of additive liquid a, 1.6 ml of Desmodur N3300 / Mobey aliphatic isocyanate (10% MEK solution), 4.27 g of additive liquid b were sequentially added and stirred. A photosensitive layer coating solution was obtained.

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

<< Preparation of surface protective layer coating liquid >>
While stirring MEK865g, cellulose acetate butyrate (above: CAB171-15) 96g, polymethylmethacrylic acid (Rohm & Haas Co., Ltd .: Paraloid A-21) 4.5g, vinyl sulfone compound (VSC) 1.5g, Benztriazole (1.0 g) and fluorine-based activator (Asahi Glass Co., Ltd .: Surflon KH40) (1.0 g) were added and dissolved. Next, 30 g of the above matting agent dispersion was added and stirred to prepare a surface protective layer coating solution.

<Photosensitive layer side coating>
The photothermographic material was prepared by simultaneously applying the photosensitive layer coating solution and the surface protective layer coating solution in a multilayer manner using an extrusion coater. The coating was carried out so that the photosensitive layer had a coating silver amount of 1.9 g / m ² and the surface protective layer had a dry film thickness of 2.5 μm. Thereafter, drying was performed for 10 minutes using a drying air having a drying temperature of 75 ° C. and a dew point temperature of 10 ° C. to obtain coated samples (1 to 20) of the photothermographic material.

  The structure of the additive used for preparing the photothermographic material is shown below.

VSC: HO—CH (CH ₂ SO ₂ CH═CH ₂ ) ₂

<< Exposure and development process >>
From the emulsion surface side of the photosensitive material produced as described above, exposure by laser scanning was given by an exposure machine using a semiconductor laser having a longitudinal multimode wavelength of 800 to 820 nm by high frequency superposition as an exposure source. At this time, an image was formed by setting the angle of the exposure surface of the photosensitive material and the exposure laser beam to 75 degrees (an image having less unevenness and unexpectedly good sharpness, etc., compared to the case where the angle is 90 degrees). was gotten).

  Thereafter, an automatic developing machine having a heat drum was used for heat development at 125 ° C. for 10 seconds so that the protective layer of the photosensitive material and the drum surface were in contact with each other. At that time, exposure and development were performed in a room adjusted to 23 ° C. and 50% RH (relative humidity). The obtained image was evaluated with a densitometer. The measurement result was evaluated by sensitivity (reciprocal of the ratio of the exposure amount giving a density 1.0 higher than that of the unexposed portion) and fog, and expressed as a relative value with the sensitivity of the photosensitive material 1 being 100.

"Raw preservation"
Three coated samples were put in a sealed container whose interior was maintained at 25 ° C. and 55% RH, and the mixture was aged at 50 ° C. for 7 days (forced aging). The second sample and a comparative sample (stored in a light-shielding container at 25 ° C.) were subjected to the same process as the sensitometric evaluation, and the fog concentration was measured. Thus, an increase 1 of fog was obtained and evaluated as a raw preservation property.

(Increase in fog 1) = (Fog during forced aging) − (Fog over time for comparison)
"Image preservation"
Two samples treated in the same manner as the sensitometric evaluation were stored for 1 day at 25 ° C / RH55% for 7 days, and the other sample was exposed to natural light for 7 days at 25 ° C / RH55%. The fog density was measured, and an increase 2 of fog was determined by the following formula and evaluated as image storability.

(Increase in fog 2) = (Fog when exposed to natural light)-(Fog when stored in the dark)
"Silver tone"
For the evaluation of silver tone, a sample that was exposed and developed so that the density after development was 1.1 ± 0.05 was prepared. This sample was irradiated for 10 hours with a light source stand having a color temperature of 7700 Kelvin and an illuminance of 11600 lux, and the color tone of silver was evaluated in the following five stages. The rank with no problem in quality assurance is 4 or more.

5: Pure black tone with no yellowness 4: Not pure black but almost yellowish 3: Partially slightly yellowish 2: Slightly yellowish on the entire surface 1: At first glance Table 1 summarizes the process of feeling yellow.

  From Table 1, Sample 1 to which the bisphenol compound of the present invention is not added has a high fog value and a large increase in fog. In sample 2 to which the comparative compound was added, the fog was suppressed, but the effect was small and the sensitivity was greatly reduced. Samples 3 to 5 to which a bisphenol compound not having a carboxyl group, which is usually used as a reducing agent (developer), is additionally added do not show the effect of suppressing fogging, but the fog is deteriorated.

  On the other hand, Samples 7 to 20 to which the bisphenol compound of the present invention is added have sufficient sensitivity, low fog, and good thermal storage stability, image storage stability and silver tone of the photothermographic material. . In particular, when used in combination with a reducing agent represented by the general formula (3), high sensitivity and favorable results were obtained. Moreover, it can be seen from the sample 6 that the sensitivity decrease increases as the amount added is increased.

Claims (5)

In a photothermographic material having an image forming layer containing organic silver, silver halide, a binder and a reducing agent on a support, a methylene bisphenol compound having at least one carboxyl group in the molecule is used as the reducing agent. A heat-developable photographic light-sensitive material characterized by containing 0.01 to 20 mol%. 2. The photothermographic material according to claim 1, wherein the methylene bisphenol compound having at least one carboxyl group in the molecule is a compound represented by the following general formula (1).

[Wherein, R ₁₁ and R ₁₂ each represents an aliphatic group, and Ar represents an aromatic group or an aromatic heterocyclic group. R ₁₃ and R ₁₄ each represents an aliphatic group. However, at least one of R ₁₁ , R ₁₂ , Ar, R ₁₃ and R ₁₄ has at least one carboxyl group. ] The photothermographic material according to claim 2, wherein the compound represented by the general formula (1) is represented by the following general formula (2).

[Wherein, R ₂₁ and R ₂₂ each represents an alkyl group or a cycloalkyl group, and R ₂₃ and R ₂₄ each represents an alkyl group. L represents a divalent linking group, and n represents 0 or 1. ] 4. The photothermographic material according to claim 1, wherein the reducing agent is represented by the following general formula (3).

[Wherein, R ₃₁ and R ₃₂ each represent a secondary or tertiary alkyl group or a cycloalkyl group, and R ₃₃ represents a hydrogen atom or an aliphatic group. R ₃₄ and R ₃₅ each represents an aliphatic group. However, none of R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ and R ₃₅ contains a carboxyl group. ] 5. An image forming method, wherein the photothermographic material according to any one of claims 1 to 4 is developed at 80 to 250 [deg.] C. after image exposure with a laser beam.