JP2005091677A - Photothermographic imaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photothermographic imaging material having high sensitivity, providing an image with little fog, and excellent in storage stability before development (abbreviated as raw stock preservability) and in storage stability after development (abbreviated as image preservability). <P>SOLUTION: The photothermographic imaging material has a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent, a cinnamic acid derivative and a binder, formed on a support. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photothermographic image forming material that forms an image by thermal development, and particularly to a photothermographic image forming material that can obtain an image with high sensitivity, little fogging, and excellent storage stability.

  In recent years, there has been a strong demand for photothermographic materials that do not generate waste liquids due to wet processing in terms of environmental protection and workability in the medical and printing fields. In particular, high-resolution and clear black images can be formed by thermal development. There is a need for techniques relating to photothermographic materials that can be used for photographic technology.

  Conventionally, this type of photothermographic image-forming material absorbs a photosensitive layer containing high-sensitivity silver halide grains spectrally sensitized with a dye, an organic silver salt, and a reducing agent, and light irradiated to the photosensitive layer. Consists of an anti-irradiation layer (AI) layer that prevents the light from being diffusely reflected by the interface, intermediate layer, adhesive layer, etc. of the support, or a backing layer (BC) provided on the opposite side of the support, if necessary. In addition, a protective layer is provided on the photosensitive layer and the BC layer to prevent scratches during handling.

In general, the photothermographic image forming material is easy to process because it produces an image only by heat development after exposure. However, since there is no fixing step, it is important to improve the storage stability of the image after development. In order to improve the storage stability after development, it is preferable to develop the image at a temperature as high as possible so that a clear image can be obtained. However, if the temperature is too high, fog is likely to occur and the sensitivity is lowered. Therefore, development is generally performed at a temperature around 120 ° C. ± 10 ° C. The use of cinnamic acid derivatives to lower fog is disclosed (for example, see Patent Document 1).
However, cinnamic acid derivatives have little effect of suppressing fogging, and it is difficult to obtain high sensitivity, and there is a limit to improving storage stability.

Although halomethane compounds used to suppress burned-out silver due to exposure to Saucusten during image interpretation after development processing are effective for fog suppression and raw storage stability (see, for example, Patent Document 2), the sensitivity decreases when the amount used is large. There was a limit to do this. In order to improve the storage stability, attempts have been made to use a compound known as a crosslinking agent for a binder, but it has not been sufficient. Although a reducing agent is disclosed as being good for improving fog sensitivity and storage stability (see, for example, Patent Document 3), it has not been sufficient.
Japanese Patent Laid-Open No. 11-295848 JP-A-9-319022 Japanese Patent Laid-Open No. 2003-98618

  An object of the present invention is to provide an excellent photothermographic image forming material which can obtain an image with high sensitivity and little fog. A second object of the present invention is to provide a photothermographic image forming material having excellent storage stability before development (abbreviated as raw storage stability) and storage stability after development (abbreviated as image storage stability).

The above object of the present invention is achieved by the following configurations.
1. A photothermographic image-forming material comprising a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent, a cinnamic acid derivative and a binder on a support.
2. 2. The photothermographic image-forming material as described in 1 above, wherein the cinnamic acid derivative is a compound represented by the following general formula (1).

(In the formula, A represents an OR _a group, R _a represents _a hydrogen atom, a substituted or unsubstituted, saturated, unsaturated linear, branched, or cyclic C ₁ -C ₂₅ alkyl group, an alkenyl chain, Represents an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted amino group, an ammonio group or an NHR _b group, and R _b represents a hydrogen atom, a substituted or unsubstituted, saturated or unsaturated linear, branched chain And cyclic C ₁ -C ₂₅ alkyl groups, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, halogen atom, hydroxy group, amino group, cyano group, acyl group, amide group , substituted or unsubstituted C ₁ -C ₂₅ alkoxy group, a substituted, unsubstituted, saturated, unsaturated, linear, branched, C ₁ -C ₂₅ hydrocarbon residue cyclic, substituted, unsubstituted Represents an aromatic ring residue or a heterocyclic residue.)
3. 1 or 2, wherein the photosensitive layer or a layer adjacent to the photosensitive layer contains at least one compound selected from a phthalazine compound, a compound having an isocyanate group, and a compound having a vinyl sulfone group. The photothermographic imaging material described.

  4). 4. The photothermographic image forming material according to any one of 1 to 3, wherein the reducing agent is contained in a layer adjacent to the photosensitive layer.

  The photothermographic image forming material of the present invention is excellent in photographic performance (sensitivity and fog characteristics), raw storability and image storability, and improved in photographic performance, raw storability and image storability during heat development. Has an effect.

  Hereinafter, the present invention will be described in detail.

  The photothermographic image-forming material of the present invention usually has a layer structure of at least two layers in which a photosensitive layer and a layer adjacent to the photosensitive layer are provided on a support, and, if necessary, the side opposite to the photosensitive layer. Are provided with a BC layer, a protective layer, and the like.

  The present invention is characterized in that the photosensitive layer of the photothermographic image-forming material contains a cinnamic acid derivative, and in particular, the derivative has a compound represented by the general formula (1), The photosensitive layer contains photosensitive silver halide grains sensitized with a spectral sensitizing dye, an organic silver salt, a reducing agent, and a binder. Further, a phthalazine compound, an isocyanate group is added to the photosensitive layer or its adjacent layer. It is preferable to contain a reducing agent for forming a silver image by developing an organic silver salt or a silver salt in at least one compound selected from a compound having an organic group and a compound having a vinyl sulfone group, or the adjacent layer.

  Hereinafter, the compound represented by the general formula (1), the phthalazine compound, the reducing agent, and the crosslinking agent contained in the photothermographic image forming material of the present invention will be sequentially described.

  The photosensitive silver halide grains contained in the photosensitive layer of the photothermographic image forming material, the organic silver salt contained in the photosensitive layer or its adjacent layer, the reducing agent, the high content contained in the photosensitive layer or its adjacent layer. The molecular binder and the like will be further described later.

In the general formula (1), A represents an OR _a group, and R _a is a hydrogen atom, substituted, unsubstituted, saturated, unsaturated, linear, branched, or cyclic C ₁ -C ₂₅ . Hydrocarbon residues (eg, methyl, ethyl, t-butyl, octyl, n-dodecyl, adamantyl, cyclohexyl, cyclohexenyl, etc.) alkali metal atoms, alkaline earth metal atoms (eg, sodium, potassium, lithium, etc.) each atom), an ammonio group, an NHR _b group, R _b is a hydrogen atom, a substituted, unsubstituted, saturated, unsaturated, linear, branched, cyclic C ₁ -C ₂₅ hydrocarbon residue Represents a group (for example, methyl, ethyl, t-butyl, octyl, n-dodecyl, adamantyl, cyclohexyl, cyclohexenyl, phenyl, naphthyl, benzyl, etc.), R ₁ , R ₂ , R ₃ and R ₄ are , Each independent Hydrogen atom, halogen atom (eg, chlorine atom, bromine atom, etc.), hydroxy group, substituted, unsubstituted amino group (amino group, diethylamino group, ethylamino group, phenylamino group, etc.), cyano group, amide group (eg, , trifluoromethyl sulfonamido, methyl sulfonamido), substituted or unsubstituted C ₁ -C ₂₅ alkoxy group (e.g., methoxy, ethoxy, t-butoxy, n- dodecyl each group oxy and the like) substituted, unsubstituted, Saturated, unsaturated, linear, branched, and cyclic C ₁ -C ₂₅ hydrocarbon groups (eg, methyl, ethyl, t-butyl, octyl, n-dodecyl, adamantyl, cyclohexyl, cyclohexenyl, etc. Group), substituted, unsubstituted aromatic ring residues (eg, phenyl, naphthyl, etc.), heterocyclic residues (eg, pyridyl, adenyl, thiophenyl, Lil, representing each residues), such as pyrrolidyl.

Examples of the substituent of the above substituent include a halogen atom (for example, chlorine atom, bromine atom), a saturated, unsaturated, linear, branched, or cyclic C _{1 to} C ₁₆ hydrocarbon residue (for example, methyl , Ethyl, t-butyl, octyl, n-dodecyl, butenyl, cyclohexyl, etc.), aromatic ring residues (eg, phenyl, naphthyl, cyclopentadienyl, norbonadienyl, etc.), heterocyclic residues Group (for example, each residue of pyridyl, thiophenyl, furyl, pyridimil, etc.).

  Preferred specific examples are shown below.

The method for synthesizing the above compounds can be synthesized with reference to JP-A-9-87236, JP-A-2000-229912 and JP-A-2002-363195. The amount of the compound used is preferably in the range of 1 × 10 ⁻⁸ to 1 × 10 ⁻² mol per 1 mol of silver halide. Addition method is dissolved in water, alcohol (eg, methanol, ethanol, isobutyl alcohol, etc.), ketones (eg, acetone, methyl ethyl ketone, isobutyl ketone, etc.), aromatic organic solvent (eg, toluene, xylene, etc.) and added. Alternatively, fine particles may be dispersed and added. In this case, jet mill dispersion, ultrasonic dispersion or homogenizer dispersion is carried out to form fine particles of 1 μm or less, and if necessary, a surfactant or viscosity modifier can be added and dispersed in water or an organic solvent. .

(Phthalazine compound)
The phthalazine compound preferably used in the present invention exhibits a development accelerating action, and its mechanism acts as a carrier for supplying silver ions from an organic silver salt to silver particles of a physical development nucleus by forming a phthalazine silver complex. It can be obtained by introducing various substituents into the phthalazine ring. A preferred phthalazine compound can be represented by the following general formula (2).

In the general formula (2), the substituents R ^{2 to} R ⁷ are each independently a hydrogen atom, a halogen atom, a cyano group, a hydroxy group, a substituted or unsubstituted alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aromatic group. Represents a group or heterocyclic group. The function of the substituent may be a group such as a group that controls diffusibility, an adsorptive group, or an acidic group. As for carbon number of an alkyl group, an alkenyl group, an alkynyl group, and an alkoxy group, 1-60 are preferable, Most preferably, it is 1-40.

  When the number of carbon atoms is more than 40, good effects on fog suppression, color tone, and storage stability cannot be obtained. These substituents may be the same as the substituents on the ring of the general formula (1). The method for synthesizing phthalazine can be synthesized with reference to WO96 / 05176A. Specific examples of preferred phthalazine compounds are shown below.

The phthalazine compound used in combination with the compound of the general formula (1) of the present invention is preferably added in an amount of 1 × 10 ⁻⁶ to 1 × 10 ⁻² mol per 1 mol of silver. The layer to be added need not be limited to the photosensitive layer in which silver halide exists, and may be an adjacent layer or an undercoat layer. The addition method can be performed in the same manner as the compound represented by the general formula (1).

  Next, organic silver salts, reducing agents, photosensitive silver halide grains, binders, dyes, matting agents and other supports used in the photothermographic image forming material of the present invention will be described in order.

(Organic silver salt)
The organic silver salt contained in the photothermographic image-forming material of the present invention is a reducible silver source, and organic acids, heteroorganic acids and acid polymer silver salts containing a reducible silver ion source are used. Also useful are organic or inorganic silver salt complexes whose ligands have a total stability constant for silver ions of 4.0-10.0. Examples of silver salts are described in Research Disclosure Nos. 17029 and 29963 and include the following: salts of organic acids (eg, gallic acid, oxalic acid, behenic acid, arachidic acid, stearic acid, palmitic acid, lauric acid) Salts of acids and the like).

(Photosensitive silver halide grains)
The photosensitive silver halide contained in the photosensitive layer of the photothermographic image-forming material of the present invention can be obtained by any method known in the field of photographic technology such as a single jet or double jet method, for example, an ammonia emulsion or neutral emulsion. It can be prepared in advance by any method such as a method or an acidic method, and then mixed with the other components of the present invention and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide and the organic silver salt, for example, U.S. Pat. Nos. 3,706,564 and 3,706 are used as protective polymers when preparing the photosensitive silver halide. , 565, 3,713,833, 3,748,143, British Patent 1,362,970, etc., and means using a polymer other than gelatin such as polyvinyl acetals Or means for enzymatic degradation of gelatin in light sensitive silver halide emulsions as described in British Patent 1,354,186, or as described in US Pat. No. 4,076,539. Thus, each means such as a means for omitting the use of the protective polymer can be applied by preparing photosensitive silver halide grains in the presence of a surfactant.

  The photosensitive silver halide preferably has a small grain size in order to keep white turbidity after image formation low and to obtain good image quality. The average particle size is 0.1 μm or less, preferably 0.01 to 0.1 μm, particularly preferably 0.02 to 0.08 μm. Further, the shape of the silver halide is not particularly limited, and examples thereof include cubic and octahedral so-called normal crystals and non-normal crystals such as spherical, rod-like, and tabular grains. The silver halide composition is not particularly limited, and may be any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide, and silver iodide.

  The amount of the silver halide is 50% by mass or less, preferably 25 to 0.1% by mass, more preferably 15 to 0.1% by mass, based on the total amount of silver halide and the organic silver salt described later. Various conditions such as reaction temperature, reaction time, reaction pressure, etc. in the step of converting a part of the organic silver salt into silver halide using the above-mentioned silver halide forming component can be appropriately set according to the purpose of preparation. Usually, the reaction temperature is −20 ° C. to 70 ° C., the reaction time is 30 seconds to 15 hours, and the reaction pressure is preferably set to atmospheric pressure.

  The photosensitive silver halide prepared by the various methods described above can be chemically sensitized by, for example, a sulfur-containing compound, a gold compound, a platinum compound, a palladium compound, a silver compound, a tin compound, a chromium compound, or a combination thereof. . Regarding the method and procedure of this chemical sensitization, for example, U.S. Pat. No. 4,036,650, British Patent No. 1,518,850 and the like, JP-A-51-22430, JP-A-51-78319. , 51-81124, etc. In order to achieve sensitization, as described in US Pat. No. 3,980,482, when a part of the organic silver salt is converted to photosensitive silver halide by the silver halide forming component. In addition, an amide compound having a low molecular weight may coexist.

  Further, these photosensitive silver halides include illuminance failure and metals belonging to Groups 6 to 10 of the Periodic Table of Elements, such as Rh, Ru, Re, Ir, Os, Fe, etc. for gradation adjustment. Ions, their complexes or complex ions can be included. In particular, it is preferable to contain ions or complex ions of metals belonging to Groups 6 to 10 of the Periodic Table of Elements. As the above metal, W, Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au are preferable. Among them, when used for a photosensitive material for printing plate making, Rh, Re, It is preferably selected from Ru, Ir, and Os. These metals can be introduced into the silver halide in the form of a complex.

The content of metal ions or complex ions is generally 1 × 10 ⁻⁹ to 1 × 10 ⁻² mol per mol of silver halide, preferably 1 × 10 ⁻⁸ to 1 × 10. ^-4 moles. The compounds providing these metal ions or complex ions are preferably added at the time of silver halide grain formation and incorporated into the silver halide grains. Preparation of silver halide grains, that is, nucleation, growth, physical ripening , May be added at any stage before or after chemical sensitization, but is preferably added at the stage of nucleation, growth and physical ripening, more preferably at the stage of nucleation and growth, most preferably Preferably, it is added at the stage of nucleation. In addition, it may be divided and added several times, or it can be uniformly contained in the silver halide grains. JP-A-63-29603, JP-A-2-306236, 3 As described in publications such as 167545, 4-76534, 6-110146, and 5-273683, the particles can be contained with a distribution. Preferably, a distribution can be provided inside the particles. These metal compounds can be added by dissolving in water or an appropriate organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides). A method in which an aqueous solution or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to a water-soluble silver salt solution or a water-soluble halide solution during particle formation, or the silver salt solution and the halide solution are mixed simultaneously. When adding a third aqueous solution, a method of preparing silver halide grains by a method of three-liquid simultaneous mixing, a method of adding a required amount of an aqueous solution of a metal compound to the reaction vessel during grain formation, or a silver halide preparation There is a method of adding and dissolving another silver halide grain that has been previously doped with metal ions or complex ions. In particular, a method of adding an aqueous solution of a metal compound powder or an aqueous solution in which a metal compound and NaCl, KCl are dissolved together is added to the water-soluble halide solution. When added to the particle surface, a necessary amount of an aqueous solution of a metal compound can be charged into the reaction vessel immediately after the formation of the particle, during or after the physical ripening, or at the chemical ripening.

(Spectral sensitizing dye)
Spectral sensitizing dyes used in the present invention are, for example, disclosed in JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242, 63-15245. No. 4,639,414, US Pat. No. 4,740,455, US Pat. No. 4,741,966, US Pat. No. 4,751,175, US Pat. No. 4,835,096 Sensitizing dyes described in each specification such as No. can be used. Useful sensitizing dyes used in the present invention are described in, for example, the literature described or cited in Research Disclosure Item 17643IV-A (December 1978, p.23) and Item 1831X (August 1978, page 437). ing. In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, the compounds described in JP-A Nos. 9-34078, 9-54409, and 9-80679 are preferably used.

(Reducing agent)
The reducing agent used in the present invention is contained in the photothermographic image forming material and exhibits a reducing action by heat development. US Pat. Nos. 3,770,448, 3,773,512, and 3,593. , 863, and the like.

  Particularly preferred reducing agents are hindered bisphenols. Examples of the hindered bisphenols include compounds represented by the following general formula (3).

  In the general formula (3), R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, a butyl group, 2,4,4-trimethylpentyl group, etc.), an aromatic ring residue (for example, a phenyl group, A naphthyl group, a cyclopentadienyl group, a cyclohexenyl group, etc.), a heterocyclic residue (furyl group, thiophenyl group, pyridyl group, oxazolyl group, thiazolyl group, etc.); 5 represents a linear or branched alkyl group (for example, a methyl group, an ethyl group, a t-butyl group, etc.) In particular, in general formula (3), R is preferably a ring residue, more preferably An unsaturated ring residue, more preferably a 2,4-dimethylcyclohexenyl group, a cyclohexenyl group, a pentadienyl group, a furyl group, or a thiophenyl group, and most preferably a cyclohexenyl group. .

  Specific examples of the compound represented by the general formula (3) are shown below. However, the present invention is not limited to the following compounds.

The amount of the compound represented by the general formula (3) is preferably 1 × 10 ⁻² to 10 mol, particularly 1 × 10 ^{−2 to} 3 mol, per mol of silver. As the addition method, a method similar to the method of adding the compound of the general formula (1) can be employed.

(Binder)
As the polymer binder used in the photosensitive layer or the non-photosensitive layer of the photothermographic image forming material of the present invention, a material preferable as a place where silver halide, an organic silver salt and a reducing agent react, a thermochromic dye is 80 to A material preferable for a reaction that is decolored by heat of 200 ° C. or less, or a material from which a base generating precursor generates a base quickly by heat is selected.

  Examples of the polymer binder include alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polymers used by dissolving in polar solvents including dimethyl sulfoxide and dimethylformamide, and water-dispersed polymers. The polymer binder of the photothermographic image forming material of the present invention may be any.

  Further, regarding the preferred polymer composition, the glass transition point is preferably from -20 ° C to 80 ° C, particularly preferably from -5 ° C to 60 ° C.

  This is because when the glass transition point exceeds 80 ° C., the temperature at which heat development is performed becomes high, and when it is less than −20 ° C., fog is likely to occur, resulting in a decrease in sensitivity and softness.

  Examples of the polymer used by dissolving in the polar solvent include cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose and ethyl cellulose, starch and derivatives thereof, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral, sodium polyacrylate, poly Ethylene oxide, acrylic acid amide-acrylic acid ester copolymer, styrene-maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein, polystyrene, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, styrene -Butadiene copolymer, acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, styrene-butadiene-a Such as Lil copolymer.

  Further, after drying, after forming a film, it is preferable that the coating film has a low equilibrium water content, specifically 1% or less, more preferably 0.1% or less.

  Particularly those having a low equilibrium water content include, for example, cellulose acetate, cellulose acetate butyrate, poly (acrylic acid esters) such as poly (methyl methacrylic acid), poly (acrylic acid), poly (methacrylic acid), poly (vinyl chloride) ), Copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters) ), Poly (urethane), phenoxy resin, poly (vinylidene chloride), poly (epoxide), poly (carbonate), poly (vinyl acetate), cellulose ester, poly (amide) .

(Crosslinking agent)
By forming the binder alone, it is possible to maintain adhesion to the lower layer and upper layer and to obtain a film strength that is difficult to get scratched. However, the use of a crosslinking agent further increases film adhesion and film strength. be able to. In addition, the crosslinking agent can not only improve the film physical properties but also improve fog suppression and storage stability. The mechanism is considered as follows. Amine compounds produced by corona discharge treatment on the surface of the support or the undercoat layer migrate to the coated photosensitive layer and increase fogging. However, the presence of a crosslinking agent that captures or inactivates the amine compound suppresses the generation of fog. The generation of the amine compound is due to the fact that nitrogen in the air, hydrogen atoms in the film, and in some cases, oxygen atoms, etc., enter a plasma state during corona discharge, and the rearrangement of atoms proceeds. Ammonia water used as a pH regulator is also considered to be left in the reaction as a causative substance for fogging. In addition, it is estimated that some of the trace amounts of impurities in the materials used as photographic additives increase fog.

  In using the crosslinking agent, there are a method of adding it to the undercoat layer, AI layer, photosensitive layer, protective layer, BC layer or BC protective layer. From the viewpoint of the stability of the coating solution, it is preferably added using a static mixer immediately before coating, but may be added at the time of preparing the coating solution. A preferred crosslinking agent is a crosslinking agent having an isocyanate group or a vinylsulfonyl group. Particularly preferred crosslinking agents include polyfunctional crosslinking agents having at least 2, more preferably 3, isocyanate groups or vinylsulfonyl groups. JP, 2003-002874, A can refer to the synthesis method of a vinyl sulfonyl compound. H-1 to H-13 are shown below as preferred crosslinking agents.

(H-1) Hexamethylene diisocyanate (H-2) Trimer of hexamethylene diisocyanate (H-3) Tolylene diisocyanate (H-4) Phenylene diisocyanate (H-5) Xylylene diisocyanate Naruto

The compound having an isocyanate group or vinylsulfonyl group used in combination with the compound of the general formula (1) of the present invention is preferably added in an amount of 1 × 10 ⁻² to 1 × 10 ³ mol per mol of silver halide. The addition position is not limited to the photosensitive layer in which silver halide exists, and may be an adjacent layer or an undercoat layer. The addition method can be performed in the same manner as the compound represented by the general formula (1).

(Dye used for AI layer or BC layer)
The photothermographic image-forming material of the present invention is provided with an AI layer or a BC layer for preventing irradiation and preventing halation of the photothermographic image-forming material as necessary, and as a dye used for the AI layer or BC layer, Any dye can be used as long as it absorbs image exposure light. Preferably, the above-described thermodecolorable dyes described in US Pat. No. 5,384,237 are used. If the dye used is not thermodecolorable, the amount used is limited to a range that does not affect the photothermographic image-forming material, but if it is a thermodecolorable dye, a sufficient amount of dye is necessary if necessary. Can be added.

(Matting agent)
The matting agent may be either organic or inorganic. Examples of the inorganic matting agent include silica described in Swiss Patent No. 330,158 and polystyrene or polymeta described in Swiss Patent No. 330,158. Acrylate, polyacrylonitrile described in US Pat. No. 3,079,257, polycarbonate described in US Pat. No. 3,022,169, and the like can be used.

  The shape of the matting agent may be either a regular shape or an irregular shape, but is preferably a regular shape, and a spherical shape is preferably used. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle size of the matting agent indicates the diameter converted into a spherical shape. The matting agent used in the present invention preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 8.0 μm. The monodispersity of the particles is preferably 50 or less, more preferably 40 or less, and particularly preferably 20 or less. Here, the monodispersity of the particles is represented by a number obtained by dividing the standard deviation of the particle size by the average value of the particle size and multiplying by 100. The method for adding the matting agent according to the present invention may be a method in which the matting agent is dispersed and applied in advance in the coating solution, or a method in which the matting agent is sprayed after the coating solution is applied and before drying is completed. May be.

(Support)
As the support, a support such as paper, synthetic paper, non-woven fabric, metal foil, and plastic film can be used, and a composite sheet combining these may be arbitrarily used.

<Image exposure>
As an exposure method, laser exposure can be performed by the methods described in JP-A-9-304869, JP-A-9-311403 and JP-A-2000-10230.

<Heat development device>
As an apparatus for developing the photothermographic image forming material, apparatuses described in JP-A Nos. 11-65067, 11-72897 and 84619 can be used.

  Hereinafter, the present invention will be specifically described with reference to examples, but the embodiment of the present invention is not limited thereto.

[Production of Photothermographic Image Forming Material (1)]
Example 1
<Preparation of underdrawn support>
The both sides of a 175 μm thick polyethylene terephthalate support were subjected to a corona discharge treatment of 600 W / m ² · min, and the following undercoat coating solution a-1 was applied on one surface to a dry film thickness of 0.8 μm. The undercoat layer A-1 is provided by drying, and the following undercoat coating solution b-1 is applied on the opposite surface so as to have a dry film thickness of 0.8 μm and dried to form the undercoat layer B-1. Provided.

<< Undercoat coating liquid a-1 >>
Copolymer latex liquid of butyl acrylate (30% by mass), t-butyl acrylate (20% by mass), styrene (25% by mass), 2-hydroxyethyl acrylate (25% by mass) (solid content 30%) 270 g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water.

<< Undercoating liquid b-1 >>
270 g of copolymer latex liquid (solid content 30%) of butyl acrylate (40 mass%), styrene (20 mass%), glycidyl acrylate (40 mass%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water.

Subsequently, a corona discharge of 600 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 A-2 is formed on the undercoat layer A-1. The following undercoating upper layer B-2 was provided on the undercoating layer B-1.

<< Undercoating Upper Layer A-2 >>
Gelatin 0.43 g / m ²
Silica particles (average particle size 3 μm) 0.01 g / m ²
<< Undercoating Upper Layer Coating Liquid B-2 >>
Styrene butadiene copolymer latex liquid (solid content 20%) 0.08 g / m ²
Polyethylene glycol (mass average molecular weight 600) 0.06 g / m ²
<Preparation of silver halide grain emulsion A>
After dissolving 7.5 g of inert gelatin and 10 mg of potassium bromide in 900 ml of water and adjusting the temperature to 28 ° C. and pH to 3.0, bromide with a molar ratio of (98/2) to 370 ml of an aqueous solution containing 74 g of silver nitrate An aqueous solution containing potassium and potassium iodide was added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. In synchronization with the addition of silver nitrate, 10 ^-6 mol / silver 1 mol of sodium salt of hexachloroiridium was added. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.036 μm, and the variation coefficient of the projected diameter area was 8%. Cubic silver iodobromide grains having a [100] face ratio of 87% were obtained. This emulsion was coagulated and precipitated using a gelatin flocculant, desalted and then 0.1 g phenoxyethanol was added to adjust the pH to 5.9 and pAg 7.5 to obtain silver halide grain emulsion A.

<Preparation of water-dispersed organic silver salt>
In 4720 ml of pure water, 111.4 g of behenic acid, 83.8 g of arachidic acid, and 54.9 g of stearic acid were dissolved at 80 ° C. Next, 540.2 ml of a 1.5 molar sodium hydroxide aqueous solution was added while stirring at high speed, and 6.9 ml of concentrated nitric acid was added, followed by cooling to 55 ° C. to obtain an organic acid sodium solution. While maintaining the temperature of the organic acid sodium solution at 55 ° C., the silver halide grain emulsion A (containing 0.038 mol of silver) and 420 ml of pure water were added and stirred for 5 minutes. Next, 760.6 ml of 1 mol silver nitrate solution was added over 2 minutes, and the mixture was further stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, the filtrate was repeatedly washed with deionized water and filtered until the electric conductivity of the filtrate reached 2 μS / cm, and finally dried to obtain 335 g of a solid content.

<Coating of photosensitive layer and BC layer>
The following layers were sequentially formed on the support provided with the undercoat layer to prepare a sample. The drying was performed at 45 ° C. for 1 minute.

<< BC layer side application >>
On the back surface side, a BC coating layer was formed by applying and drying a coating solution prepared by adding water to an aqueous dispersion or water dispersion of the following thermodecolorable dye composition and adding the following amount.

<< BC layer application >>
Inert gelatin 1.8g / m ²
Dye C 1.2 × 10 ⁻⁵ mol / m ²
Activator: N-propyloctylsulfonamidoacetic acid 0.02 g / m ²
Dihexyl sulfosuccinic acid sodium salt 0.02 g / m ²
Cross-linking agent: 1,2-bis (vinylsulfonamide) ethane 0.02 g / m ²
<< Application of BC protective layer >>
Inert gelatin 1.1 g / m ²
Cross-linking agent: 1,2-bis (vinylsulfonamide) ethane 0.01 g / m ²
Activator: N-propyl perfluorooctylsulfonamidoacetic acid
0.02 g / m ²
Matting agent (PMMA: average particle size 5 μm) 0.12 g / m ²
<< Coating on the photosensitive layer side >>
<Application of AI layer>
Binder: PBV-1 0.4 g / m ²
Dye: C (same type as BC layer)
<Application of photosensitive layer>
A coating solution was prepared by dissolving the following composition in a methyl ethyl ketone solvent for forming a photosensitive layer. This coating solution was kept at around 35 ° C. and dried so as to have the following weight. An amount of the preparation solution that was 0.86 g / m ² as silver amount was mixed with the polymer binder.

Binder: PVB-1 (same type as AI layer) 2.6 g / m ²
Compounds of general formula (1): listed in Table 1 3.2 × 10 ⁻⁴ mol / m ²
For comparison, the specific example UV-33 used in the examples of JP-A-11-295848 is used as (PZ-0). 3.5 × 10 ⁻⁴ mol / ²
Compound represented by the general formula (2): listed in Table 1 2.2 × 10 ⁻⁴ mol / m ²
Compound represented by formula (3): listed in Table 1 1.4 × 10 ⁻⁴ mol / m ²
2,5-di-t-butyl-4-methylphenol (HP-O) for comparison
1.4 × 10 ⁻⁴ mol / m ²
Spectral sensitizing dye D 2 × 10 ⁻⁵ mol / m ²
Antifoggant-1: pyridinium hydrobromide perbromide 0.3 mg / m ²
Antifoggant-2: isothiazolone 1.2 mg / m ²
Cross-linking agent: listed in Table 1 2 × 10 ⁻⁵ mol / m ²
Phenylaminoethoxytrimethoxysilane (H-0) was used as a comparative crosslinking agent.

3.5 × 10 ⁻⁵ mol / m ²
<Surface protective layer>
A coating solution prepared by adding the following composition was applied and dried on the photosensitive layer so as to have the following weight to form a surface protective layer.

Cellulose acetate butyrate 1.2 g / m ²
4-methylphthalic acid 0.7 g / m ²
Tetrachlorophthalic acid 0.2g / m ²
Tetrachlorophthalic anhydride 0.5g / m ²
Silica matting agent (average particle size 5 μm) 0.5 g / m ²
Surfactant E 0.1 g / m ²

<Evaluation of photographic performance>
After preparing 50 samples of the size of 5 cm × 12 cm, the sample was divided into two, and one was exposed to a 810 nm semiconductor laser exposure sensitometer in an atmosphere of 46% RH at 23 ° C. After heating at ° C for 18 seconds, the photographic performance of the obtained sample was evaluated (room temperature photographic performance). The other one was heat sealed under reduced pressure (10 hPa) in a confidential aluminum foil packaging bag at 23 ° C. and RH 46%, stored in a constant temperature room at 48 ° C. for 30 days, and then similarly exposed and developed to evaluate performance ( High-temperature photographic performance, ie raw storage). The laser exposure and the development treatment were performed in a room adjusted to a humidity of 25% ± 1 ° C. and a relative humidity of 54% ± 1%.

  The sensitivity and fog were measured with a transmitted light densitometer. The sensitivity was evaluated by the reciprocal of the ratio of the exposure amount giving a density 0.3 higher than the fog density, and expressed by relative evaluation with the sample 101 as a reference (100). The storage stability after image development (image storage stability) is a light fog value after a developed sample is left on a shaucusten having a luminance of 10,000 lux for 10 hours.

  As is clear from the results in Table 1, it can be seen that the sample of the present invention is superior in both photographic performance and image storage stability compared to the comparative sample.

Claims (4)

A photothermographic image-forming material comprising a photosensitive layer containing photosensitive silver halide grains, an organic silver salt, a reducing agent, a cinnamic acid derivative and a binder on a support. The photothermographic image-forming material according to claim 1, wherein the cinnamic acid derivative is a compound represented by the following general formula (1).

(In the formula, A represents an OR _a group, R _a represents _a hydrogen atom, a substituted or unsubstituted, saturated, unsaturated linear, branched, or cyclic C ₁ -C ₂₅ alkyl group, an alkenyl chain, Represents an alkali metal atom, an alkaline earth metal atom, a substituted or unsubstituted amino group, an ammonio group or an NHR _b group, and R _b represents a hydrogen atom, a substituted or unsubstituted, saturated or unsaturated linear, branched chain And cyclic C ₁ -C ₂₅ alkyl groups, R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, halogen atom, hydroxy group, amino group, cyano group, acyl group, amide group , substituted or unsubstituted C ₁ -C ₂₅ alkoxy group, a substituted, unsubstituted, saturated, unsaturated, linear, branched, C ₁ -C ₂₅ hydrocarbon residue cyclic, substituted, unsubstituted Represents an aromatic ring residue or a heterocyclic residue.) 3. The photosensitive layer or a layer adjacent to the photosensitive layer contains at least one compound selected from a phthalazine compound, a compound having an isocyanate group, and a compound having a vinyl sulfone group. The photothermographic image-forming material described in 1. The photothermographic image-forming material according to claim 1, wherein the reducing agent is contained in a layer adjacent to the photosensitive layer.